JP2005242163A - LIGHT MODULATION DEVICE, OPTICAL DISPLAY DEVICE, LIGHT MODULATION METHOD, AND IMAGE DISPLAY METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light modulation device suitable for realizing a luminance dynamic range and an increase in the number of gradations, an improvement in luminance and image quality of a display image, and a miniaturization of the device.
A projection display device 100 includes a light source 10, dichroic mirrors 44a and 44b that separate light from the light source 10 into RGB three primary colors, and a plurality of light beams that are incident on the light beams separated by the dichroic mirrors 44a and 44b. A color modulation light valve, a dichroic prism 48 that synthesizes light from each color modulation light valve, a DMD 50, and a relay lens 16 that forms a combined optical image of the dichroic prism 48 on the pixel surface of the DMD 50; The bulb, the relay lens 16 and the DMD 50 are arranged according to Shine-Pluff's law, and a distortion for correcting a distortion generated on the pixel surface of the DMD 50 is given to an image formed by the color modulation light valve.
[Selection] Figure 1

Description

  The present invention relates to an apparatus and method for modulating light from a light source via a plurality of light modulation elements, and in particular, to expand the dynamic luminance range and the number of gradations, improve the luminance and image quality of a display image, and reduce the size of the apparatus. The present invention relates to a light modulation device, an optical display device, a light modulation method, and an image display method that are suitable for realizing the image processing.

In recent years, LCD (Liquid Crystal Display), EL, plasma display, CRT (Cathode Ray Tube), projectors, and other optical display devices have seen remarkable improvements in image quality, and the resolution and color gamut have achieved performance that is almost comparable to human visual characteristics. It is being done. However, regarding the luminance dynamic range, the reproduction range is limited to about 1 to 10 ² [nit], and the number of gradations is generally 8 bits. On the other hand, human visual perception has a luminance dynamic range perceived at a time of about 10 ⁻² to 10 ⁴ [nit], and the luminance discrimination capability is about 0.2 [nit], which is the number of gradations. Is converted to 12 bits. Looking at the display image of the current optical display device through such visual characteristics, the narrowness of the luminance dynamic range is conspicuous, and in addition, the reality and power of the display image are insufficient due to the lack of gradation in the shadow part and highlight part. Will feel unsatisfactory.

  Further, in computer graphics (hereinafter abbreviated as CG) used in movies, games, etc., display data (hereinafter referred to as HDR (High Dynamic Range) display data) that represents a luminance dynamic range and gradation number close to human vision. The movement of pursuing the reality of depiction is being mainstream. However, since the performance of the optical display device that displays it is insufficient, there is a problem that the expressive power inherent in the CG content cannot be fully exhibited.

Further, in the next OS (Operating System), the adoption of a 16-bit color space is planned, and the luminance dynamic range and the number of gradations are dramatically increased as compared with the current 8-bit color space. Therefore, it is desired to realize an optical display device that can make use of the 16-bit color space.
Among optical display devices, projection display devices such as liquid crystal projectors and DLP projectors are capable of displaying on a large screen and are effective in reproducing the reality and power of display images. In this field, the following proposals have been made to solve the above problems.

  As a projection display device with a high dynamic range, for example, there is a technique disclosed in Patent Document 1, which includes a light source, a first light modulation element that modulates luminance in the entire wavelength region of light, and a wavelength region of light. Among these, each wavelength region of the RGB three primary colors is provided with a second light modulation element that modulates the luminance of the wavelength region, and the light from the light source is modulated by the first light modulation element to form a desired luminance distribution, and its optical image Is imaged on the pixel surface of the second light modulation element, color-modulated, and second-order modulated light is projected. Each pixel of the first light modulation element and the second light modulation element is individually controlled based on the first control value and the second control value determined from the HDR display data. As the light modulation element, a transmission type light modulation element having a pixel structure or a segment structure whose transmittance can be controlled independently and capable of controlling a two-dimensional transmittance distribution is used. A typical example is a liquid crystal light valve.

  Consider a case where a light modulation element having a dark display transmittance of 0.2% and a bright display transmittance of 60% is used. With a single light modulation element, the luminance dynamic range is 60 / 0.2 = 300. Since the conventional projection display apparatus corresponds to optically arranging light modulation elements having a luminance dynamic range of 300 in series, a luminance dynamic range of 300 × 300 = 90000 can be realized. The same idea holds for the number of gradations, and an 8-bit gradation light modulation element is optically arranged in series, whereby a gradation number exceeding 8 bits can be obtained.

In addition, as a projection display device that realizes a high luminance dynamic range, for example, a projection display device disclosed in Patent Document 2 is known.
The invention described in Patent Document 2 includes a DMD (Digital Micromirror Device) in which a plurality of pixels are arranged in a line, an illumination unit that irradiates a light beam to the DMD, a processing unit that converts an input video signal into a DMD drive signal, An optical scanning unit that scans the light beam modulated by the DMD and a projection lens that projects the light beam from the light scanning unit onto the screen surface, and the illumination unit modulates the amount of irradiation light according to the input video signal.
Japanese Patent Laid-Open No. 2001-1000068 JP 2001-174919 A

FIG. 21 is a diagram illustrating a pixel surface of each pixel of the transmissive liquid crystal light valve.
Since the transmissive liquid crystal light valve is provided with transistors and signal wirings for driving pixel electrodes in each pixel surface, as shown in FIG. 21, it means an opening (a part through which light is transmitted) in each pixel. ) Becomes a window shape, and the opening ratio is generally 60% or less.
Therefore, in the invention described in Patent Document 1, in order to ensure the brightness of the display image, the optical image of the opening of each pixel of the first light modulation element is used as the opening of the corresponding pixel of the second light modulation element. Therefore, it is necessary to perform alignment so as to form an image accurately, and high alignment accuracy is required.

FIG. 22 is a diagram illustrating the configuration of the optical paths of the first light modulation element and the second light modulation element in the projection display device described in Patent Document 1. Although other optical elements such as mirrors are arranged on the actual optical path, these optical elements are omitted in FIG. 22 for easy understanding of the following description.
In the optical system of FIG. 22, the first light modulation element 130 for luminance modulation is disposed on the light source side with the fly-eye lenses 112a and 112b interposed therebetween, and the color modulation device is disposed on the opposite side of the light source with the fly-eye lenses 112a and 112b interposed therebetween. The second light modulation element 140 is arranged. In this optical system, an optical image of the first light modulation element is formed on the second light modulation element by the fly-eye lenses 112a and 112b and the condenser lens 112d. By the way, the fly-eye lenses 112a and 112b and the condenser lens 112d are optical elements used for the purpose of uniforming the luminance distribution and have low imaging performance.

For this reason, in the invention described in Patent Document 1, it is difficult to accurately transmit the optical image of the first light modulation element to the pixel surface of the second light modulation element, and the luminance of the display image is low. There was a problem of lowering.
FIG. 23 is a diagram illustrating a pixel surface of each pixel of the reflective light modulation element.
In contrast to the transmissive liquid crystal display element, a reflection type light modulation element such as a DMD has a light shielding portion such as a signal line and a driving transistor formed under the reflection pixel electrode. Therefore, as shown in FIG. In general, the aperture ratio of the opening (refers to a portion that reflects light) is 90% or more. Therefore, if the first light modulation element or the second light modulation element is formed of a reflective light modulation element, the luminance of the display image can be improved.

Patent Document 1 describes that the second light modulation element can be configured by DMD, but the transmission type light modulation element is simply replaced with DMD, and thus has the following problems. .
As a projection display device using a DMD, a projection display device adopting an “off-axis optical system” in which light is incident obliquely on the DMD and emitted light is emitted in a direction different from the incident direction. Has been proposed.

  However, in the invention described in Patent Document 1, when the second light modulation element is arranged so as to be an off-axis optical system, the optical image of the first light modulation element is not with respect to the pixel surface of the second light modulation element. Since the image is formed obliquely, blurring or trapezoidal distortion occurs on the pixel surface of the second light modulation element. Therefore, when a desired light intensity distribution is formed by the first light modulation element, and the optical image is formed on the pixel surface of the second light modulation element and second-order modulated by the second light modulation element, the first light modulation is performed. Since trapezoidal distortion occurs in the image formed by the elements, accurate secondary modulation cannot be performed. Therefore, the reality and power of the image inherent in the HDR display data cannot be sufficiently reproduced.

On the other hand, in the invention described in Patent Document 2, a solid-state laser or a semiconductor laser is used as a light source. However, when a solid-state laser is used, there is a problem that the apparatus becomes large. In addition, when a semiconductor laser is used as the light source, there is a problem that the luminance of the display image is lowered because the light output is small.
Therefore, the present invention has been made paying attention to such an unsolved problem of the conventional technology, and has been made to expand the luminance dynamic range and the number of gradations, improve the luminance and image quality of the display image, and the apparatus. An object of the present invention is to provide a light modulation device, an optical display device, a light modulation method, and an image display method that are suitable for realizing the downsizing of the display.

[Invention 1] In order to achieve the above object, an optical modulation device of Invention 1 comprises:
A first light modulation element; a second light modulation element; and a relay lens that forms an optical image of the first light modulation element on a light receiving surface of the second light modulation element. An apparatus for modulating light from a light source via the second light modulation element,
The second light modulation element is constituted by a reflection type light modulation element,
The first light modulation element, the relay lens, and the second light modulation element are arranged according to Shine-Pluff's law.

  With such a configuration, the light from the light source is first-order modulated by the first light modulation element, and the optical image of the first light modulation element is formed on the light receiving surface of the second light modulation element via the relay lens. Is done. At this time, since the first light modulation element, the relay lens, and the second light modulation element are arranged in accordance with Shine-Proff's law, the image plane of the optical image of the first light modulation element is the light receiving surface of the second light modulation element. Matches. The light from the first light modulation element is secondarily modulated by reflecting the light from the first light modulation element by the second light modulation element.

  Thereby, since the light from the light source is modulated via the first light modulation element and the second light modulation element, an effect that a relatively high luminance dynamic range and gradation number can be realized is obtained. In addition, since the second light modulation element is composed of a reflective light modulation element having a high aperture ratio, the brightness of the display image can be increased to some extent even if the alignment accuracy between the first light modulation element and the second light modulation element is not high. Can be secured. Therefore, the effect that it can suppress that the brightness | luminance of a display image falls compared with the past is also acquired. Further, since the imaging surface of the optical image of the first light modulation element coincides with the light receiving surface of the second light modulation element, blurring of the optical image formed on the pixel surface of the second light modulation element is suppressed. can do. Accordingly, an effect that the possibility that the image quality is deteriorated can be reduced as compared with the conventional case. Furthermore, since it is not necessary to use a solid laser or a semiconductor laser as a light source, it is possible to obtain an effect that the apparatus can be reduced in size and brightness as compared with the conventional case.

Here, as the light source, any medium that generates light can be used. For example, the light source may be a light source built in an optical system such as a lamp, or may be a sun light or an indoor light. It may be an external light source. Hereinafter, the same applies to the light modulation method of the ninth aspect.
In addition, the first light modulation element may have any configuration as long as it modulates light, and the structure may be, for example, a single plate type composed of a single light modulation element. In addition, a multi-plate type composed of a plurality of light modulation elements may be used. As a function, for example, the luminance of the entire wavelength region of light may be modulated, or the luminance of the specific wavelength region may be modulated for a plurality of different specific wavelength regions out of the wavelength region of light. It may be. The same applies to the optical display device of the invention 2, the light modulation method of the invention 9, and the image display method of the invention 10.

  In addition, the second light modulation element may have any configuration as long as it reflects light, and the structure may be, for example, a single plate type composed of a single light modulation element. In addition, a multi-plate type composed of a plurality of light modulation elements may be used. As a function, for example, the luminance of the entire wavelength region of light may be modulated, or the luminance of the specific wavelength region may be modulated for a plurality of different specific wavelength regions out of the wavelength region of light. It may be. Hereinafter, the same applies to the light modulation method of the ninth aspect.

[Invention 2] On the other hand, in order to achieve the above object, an optical display device of Invention 2 comprises:
A light source, a light separating unit that separates light from the light source into a plurality of different specific wavelength regions, a plurality of first light modulation elements that respectively enter the light separated by the light separating unit, and the first A light combining means for combining light from the light modulation elements; a second light modulation element; and a relay lens for forming a combined optical image of the light combination means on a light receiving surface of the second light modulation element. An apparatus for displaying an image by modulating light from the light source via one light modulation element and the second light modulation element,
The second light modulation element is constituted by a reflection type light modulation element,
Each of the first light modulation elements, the relay lens, and the second light modulation element are arranged according to Shine-Pluff's law.

  With such a configuration, the light from the light source is separated into light of a plurality of specific wavelength regions by the light separating means, and each separated light from the light separating means is primarily modulated by each first light modulation element. The Next, light from each first light modulation element is combined by the light combining means, and a combined optical image of the light combining means is formed on the light receiving surface of the second light modulation element via the relay lens. At this time, since the first light modulation element, the relay lens, and the second light modulation element are arranged in accordance with Shine-Proff's law, the image plane of the optical image of each first light modulation element is the light reception of the second light modulation element. Match the face. Then, the light from the light combining means is secondarily modulated by reflecting the light from the light combining means by the second light modulation element.

  Thereby, since the light from the light source is modulated via the first light modulation element and the second light modulation element, an effect that a relatively high luminance dynamic range and gradation number can be realized is obtained. In addition, since the second light modulation element is composed of a reflective light modulation element having a high aperture ratio, the brightness of the display image can be increased to some extent even if the alignment accuracy between the first light modulation element and the second light modulation element is not high. Can be secured. Therefore, the effect that it can suppress that the brightness | luminance of a display image falls compared with the past is also acquired. Further, since the image formation surface of the optical image of each first light modulation element coincides with the light reception surface of the second light modulation element, blurring occurs in the optical image formed on the pixel surface of the second light modulation element. Can be suppressed. Accordingly, an effect that the possibility that the image quality is deteriorated can be reduced as compared with the conventional case. Furthermore, since it is not necessary to use a solid laser or a semiconductor laser as a light source, it is possible to obtain an effect that the apparatus can be reduced in size and brightness as compared with the conventional case.

  Here, the specific wavelength region is not limited to be set for each of the RGB three primary colors, but can be arbitrarily set as necessary. However, if it is set for each of the RGB primary colors, the existing liquid crystal light valve can be used as it is, which is advantageous in terms of cost. The same applies to the image display method of the tenth invention.

[Invention 3] Furthermore, the optical display device of Invention 3 is the optical display device of Invention 2,
The optical axis of the incident light incident on the second light modulation element via the first light modulation element, and the emitted light reflected from the second light modulation element and emitted from the second light modulation element An image deforming means for applying a distortion corresponding to a predetermined angle formed by the optical axis to the image formed by each of the first light modulation elements is provided.

With such a configuration, the image deforming unit gives distortion corresponding to a predetermined angle to the image formed by each first light modulation element. Therefore, an image formed by each first light modulation element is formed obliquely with respect to the light receiving surface of the second light modulation element, but the distortion generated on the light receiving surface of the second light modulation element is reduced. Imaged.
Thereby, even if the second light modulation elements are arranged so as to be an off-axis optical system, an image formed by each first light modulation element is formed on the light receiving surface of the second light modulation element with reduced distortion. Therefore, it is possible to perform high-precision light modulation with the second light modulation element. Therefore, an effect that the possibility that the image quality is deteriorated can be further reduced is obtained.

[Invention 4] Furthermore, the optical display device of Invention 4 is the optical display device of Invention 3,
The first light modulation element is a light modulation element having a plurality of pixels capable of independently controlling light propagation characteristics;
The second light modulation element is a light modulation element having a plurality of pixels capable of independently controlling light reflection characteristics;
The image deforming means is based on a pixel correspondence table and display data defining a correspondence relationship between the pixels of the first light modulation element and the pixels of the second light modulation element in consideration of distortion according to the predetermined angle. One of a light propagation characteristic and a control value of the first light modulation element and a reflection characteristic and a control value of the second light modulation element are determined.

  With such a configuration, the image transformation means determines the light propagation characteristics and control values of the first light modulation element and the reflection characteristics and control values of the second light modulation element based on the pixel correspondence table and display data. One of them is decided. Since the correspondence relationship between the pixels of the first light modulation element and the pixels of the second light modulation element is defined in the pixel correspondence relationship table in consideration of distortion according to a predetermined angle, the determined light propagation characteristics, reflection When the first light modulation element or the second light modulation element is controlled based on the characteristic or the control value, distortion corresponding to a predetermined angle is given to the image formed by each first light modulation element.

  Accordingly, it is possible to relatively easily determine any one of the light propagation characteristic and the control value of the first light modulation element and the reflection characteristic and the control value of the second light modulation element in consideration of the distortion corresponding to the predetermined angle. The effect of being able to be obtained.

[Invention 5] By the way, HDR display data is image data that can realize a high luminance dynamic range that cannot be realized by a conventional image format such as sRGB, and a pixel value indicating a luminance level of a pixel is assigned to all pixels of the image. Storing. When the luminance level of the pixel p in the HDR display data is Rp, the transmittance of the pixel corresponding to the pixel p of the first light modulation element is T1, and the reflectance of the pixel corresponding to the pixel p of the second light modulation element is T2. The following expressions (1) and (2) hold.

Rp = Tp × Rs (1)
Tp = T1 × T2 × G (2)

However, in the above formulas (1) and (2), Rs is the luminance of the light source, G is the gain, and both are constants. Tp is a light modulation rate.

From the above equations (1) and (2), it can be seen that there are an infinite number of combinations of T1 and T2 for the pixel p. However, T1 and T2 may not be arbitrarily determined. Since the image quality may deteriorate depending on the method of determination, T1 and T2 need to be appropriately determined in consideration of the image quality.
As a result of intensive studies, the present inventors have found that the following factors influence the deterioration of image quality depending on how T1 and T2 are determined.

  When the first light modulation element and the second light modulation element have different resolutions, for one pixel p1 of the first light modulation element, the pixel p1 overlaps with a plurality of pixels of the second light modulation element on the optical path, and vice versa. In addition, for one pixel p2 of the second light modulation element, the pixel p2 may overlap with a plurality of pixels of the first light modulation element on the optical path. Here, when calculating the transmittance T1 for the pixel p1 of the first light modulation element, if the reflectance T2 of a plurality of overlapping pixels of the second light modulation element is determined, the average value of the reflectance T2 or the like is calculated. It is conceivable that the transmittance T1 is calculated by the above equations (1) and (2), assuming that the calculated average value and the like are considered as the reflectance T2 of the pixel corresponding to the pixel p1 of the second light modulation element. However, since the average value is regarded as the reflectance T2 of the second light modulation element to the last, an error is inevitably generated there. This error occurs regardless of the order of determination, whether the transmittance T1 of the first light modulation element is determined first or the reflectance T2 of the second light modulation element is determined first. Of the first light modulation element and the second light modulation element, the one that determines the display resolution has a large visual influence, so it is better to minimize the error.

  Therefore, let us examine how the magnitude of the error changes depending on the order of determination. First, consider determining the reflectance T2 of the second light modulation element first. The transmittance T1 of the pixel p1 of the first light modulation element is calculated by calculating an average value or the like of the reflectance T2 of a plurality of overlapping pixels of the second light modulation element, and based on the calculated average value and the HDR display data. It can be calculated by (1) and (2). As a result, from the viewpoint of the pixel p1 of the first light modulation element, the transmittance T1 has an error with respect to the reflectance T2 of the plurality of overlapping pixels of the second light modulation element, but the degree of error is an average value. This is the degree of error caused by statistical calculations such as. On the other hand, when viewed from the pixel p2 of the second light modulation element, the reflectance T2 can be obtained by calculating the average value or the like of the transmittance T1 of a plurality of overlapping pixels of the first light modulation element. On the other hand, a large error may occur that does not satisfy the above equations (1) and (2). This is because the reverse relationship is not necessarily established even if a relationship (a relationship satisfying the above formulas (1) and (2)) with a plurality of overlapping pixels of the second light modulation element is defined based on the pixel p1. It is thought to be caused by Therefore, there is a high possibility that the error of the reflectance T2 of the second light modulation element becomes larger.

The same applies to the opposite case, and when the transmittance T1 of the first light modulation element is determined first, the error of the transmittance T1 of the first light modulation element is likely to be larger.
From the above, from the viewpoint of improving the image quality, the reflectance or transmittance (hereinafter referred to as reflectance or the like) of the first light modulation element and the second light modulation element that determines the display resolution will be described later. The conclusion is that the influence of the error may be less if it is determined.

Based on this conclusion, the optical display device of invention 5 is the optical display device of invention 4,
The second light modulation element is a light modulation element that determines display resolution;
Further, a reflection characteristic temporary determination unit that temporarily determines the reflection characteristic of each pixel of the second light modulation element, the first light modulation element based on the reflection characteristic temporarily determined by the reflection characteristic temporary determination unit and the display data A light propagation characteristic determining means for determining a light propagation characteristic of each pixel of the first and a first control for determining a control value of each pixel of the first light modulation element based on the light propagation characteristic determined by the light propagation characteristic determining means Value determining means; reflection characteristic determining means for determining the reflection characteristics of each pixel of the second light modulation element based on the light propagation characteristics determined by the light propagation characteristic determining means and the display data; and the reflection characteristic determining means Second control value determining means for determining a control value of each pixel of the second light modulation element based on the reflection characteristic determined in
The image deforming means is applied to any one of the light propagation characteristic determining means, the first control value determining means, the reflection characteristic determining means, and the second control value determining means.

  With such a configuration, the reflection characteristic of each pixel of the second light modulation element is temporarily determined by the reflection characteristic temporary determination unit. Next, the light propagation characteristic determination means determines the light propagation characteristics of each pixel of the first light modulation element based on the provisionally determined reflection characteristic and display data of the second light modulation element, and the first control value determination means determines the light propagation characteristic. The control value of each pixel of the first light modulation element is determined based on the determined light propagation characteristic of the first light modulation element. Then, the reflection characteristic determination unit determines the reflection characteristic of each pixel of the second light modulation element based on the determined light propagation characteristic and display data of the first light modulation element, and the second control value determination unit determines the reflection characteristic. Based on the reflection characteristics of the second light modulation element, the control value of each pixel of the second light modulation element is determined.

Thereby, since the reflection characteristic of the second light modulation element that determines the display resolution is determined later, it is possible to suppress the influence of errors and to reduce the possibility that the image quality is deteriorated. It is done.
Here, the light propagation characteristics refer to characteristics that affect light propagation, and include, for example, light transmission characteristics, reflection characteristics, refraction characteristics, and other propagation characteristics. The same applies to the optical display device of the invention 6 and the image display methods of the inventions 13 and 14.

  Further, the reflection characteristic determining means may have any configuration as long as the reflection characteristic of each pixel of the second light modulation element is determined based on the light propagation characteristic determined by the light propagation characteristic determining means and the display data. The calculation may be performed based on the light propagation characteristics determined by the light propagation characteristic determination means, and the calculation or conversion may be performed based on the calculation result or the conversion result. The reflection characteristic of each pixel of the second light modulation element may be determined. For example, since the control value determined by the first control value determining means is determined based on the light propagation characteristic determined by the light propagation characteristic determining means, the reflection characteristic determining means is the control determined by the first control value determining means. Based on the value and the display data, the reflection characteristic of each pixel of the second light modulation element can be determined.

[Invention 6] Furthermore, the optical display device of Invention 6 is the optical display device of Invention 4,
The first light modulation element is a light modulation element that determines display resolution;
Further, a light propagation characteristic provisionally determining unit that provisionally determines a light propagation characteristic of each pixel of the first light modulation element, the light propagation characteristic provisionally determined by the light propagation characteristic provisional determination unit, and the display data Reflection characteristic determining means for determining the reflection characteristic of each pixel of the two-light modulation element, and first control for determining a control value of each pixel of the second light modulation element based on the reflection characteristic determined by the reflection characteristic determination means Value determining means, light propagation characteristic determining means for determining light propagation characteristics of each pixel of the first light modulation element based on the reflection characteristics determined by the reflection characteristic determining means and the display data, and the light propagation characteristic determination Second control value determining means for determining a control value of each pixel of the first light modulation element based on the light propagation characteristic determined by the means,
The image deformation means is applied to any one of the reflection characteristic determination means, the first control value determination means, the light propagation characteristic determination means, and the second control value determination means.

  With such a configuration, the light propagation characteristic provisional determination means provisionally determines the light propagation characteristic of each pixel of the first light modulation element. Next, the reflection characteristic determination unit determines the reflection characteristic of each pixel of the second light modulation element based on the temporarily determined light propagation characteristic and display data of the first light modulation element, and the first control value determination unit Based on the determined reflection characteristic of the second light modulation element, the control value of each pixel of the second light modulation element is determined. Then, the light propagation characteristic determination means determines the light propagation characteristics of each pixel of the first light modulation element based on the determined reflection characteristic and display data of the second light modulation element, and the second control value determination means Based on the determined light propagation characteristic of the first light modulation element, the control value of each pixel of the first light modulation element is determined.

Thereby, since the light propagation characteristic of the first light modulation element that determines the display resolution is determined later, the influence of the error can be suppressed, and the possibility that the image quality can be reduced can be reduced. can get.
Here, the light propagation characteristic determining means may have any configuration as long as it determines the light propagation characteristics of each pixel of the first light modulation element based on the reflection characteristics determined by the reflection characteristic determining means and the display data. It is not limited to the reflection characteristic itself determined by the reflection characteristic determination unit, but is calculated or converted based on the reflection characteristic determined by the reflection characteristic determination unit, and the first light is calculated based on the calculation result or the conversion result. The light propagation characteristics of each pixel of the modulation element may be determined. For example, since the control value determined by the first control value determining means is determined based on the reflection characteristic determined by the reflection characteristic determining means, the light propagation characteristic determining means is the control value determined by the first control value determining means. Based on the display data, the light propagation characteristics of each pixel of the first light modulation element can be determined.

[Invention 7] Furthermore, the optical display device of Invention 7 is the optical display device of any one of Inventions 2 to 6,
The second light modulation element is composed of DMD.
With such a configuration, since the second light modulation element is configured with DMD having a high aperture ratio, the brightness of the display image can be obtained even if the alignment accuracy between the first light modulation element and the second light modulation element is not high. Can be secured to some extent. In addition, the second light modulation element can be digitally driven.

[Invention 8] Furthermore, the optical display device of Invention 8 is the optical display device of any one of Inventions 2 to 6,
The second light modulation element is composed of a reflective liquid crystal display element.
With such a configuration, since the second light modulation element is configured by a reflective liquid crystal display element having a high aperture ratio, even if the alignment accuracy between the first light modulation element and the second light modulation element is not high, The brightness of the display image can be secured to some extent. In addition, polarization characteristics can be maintained in light transmission between the first light modulation element and the second light modulation element. Therefore, it is possible to further suppress the decrease in the luminance of the display image. In addition, as compared with the case of using the DMD, since the definition can be increased, the image quality can be improved and the manufacturing cost can be reduced.

[Invention 9] On the other hand, in order to achieve the above object, the light modulation method of Invention 9 includes:
A first modulation step for modulating light from the light source via the first light modulation element, and an optical for forming an optical image of the first light modulation element on the light receiving surface of the second light modulation element via the relay lens. A method of modulating light from the light source, comprising: an image forming step; and a secondary modulation step of modulating light from the first light modulation element via the second light modulation element,
The second light modulation element is a reflective light modulation element,
The first light modulation element, the relay lens, and the second light modulation element are arranged according to Shine-Pluff's law.
Thereby, an effect equivalent to that of the light modulation device of aspect 1 is obtained.

[Invention 10] On the other hand, in order to achieve the above object, an image display method of Invention 10 includes:
A light separation step for separating the light from the light source through a light separation means for separating the light into a plurality of different specific wavelength regions, and for each separated light from the light separation means, through the first light modulation element A first modulation step for modulating the separated light, a light synthesis step for synthesizing the separated light from the first light modulation elements via light synthesis means for synthesizing the light, and a light synthesis means via a relay lens. An optical image forming step of forming a combined optical image on the light receiving surface of the second light modulation element; and a second modulation step of modulating light from the light combining means via the second light modulation element; A method of displaying an image by modulating light from the light source,
The second light modulation element is a reflective light modulation element,
Each of the first light modulation elements, the relay lens, and the second light modulation element are arranged according to Shine-Pluff's law.
Thereby, an effect equivalent to that of the optical display device of aspect 2 is obtained.

[Invention 11] Furthermore, the image display method of Invention 11 is the image display method of Invention 10,
The optical axis of the incident light incident on the second light modulation element via the first light modulation element, and the emitted light reflected from the second light modulation element and emitted from the second light modulation element An image transformation step is provided, in which a distortion corresponding to a predetermined angle formed by the optical axis is applied to an image formed by each of the first light modulation elements.
Thereby, an effect equivalent to that of the optical display device of aspect 3 is obtained.

[Invention 12] Further, the image display method of Invention 12 is the image display method of Invention 11,
The first light modulation element is a light modulation element having a plurality of pixels capable of independently controlling light propagation characteristics;
The second light modulation element is a light modulation element having a plurality of pixels capable of independently controlling light reflection characteristics;
The image deformation step is based on a pixel correspondence table and display data that define a correspondence relationship between the pixels of the first light modulation element and the pixels of the second light modulation element in consideration of distortion according to the predetermined angle. One of the light propagation characteristic and control value of the first light modulation element and the reflection characteristic and control value of the second light modulation element are determined.
Thereby, an effect equivalent to that of the optical display device of aspect 4 is obtained.

[Invention 13] Further, the image display method of Invention 13 is the image display method of Invention 12,
The second light modulation element is a light modulation element that determines display resolution;
Further, a reflection characteristic provisional determination step for provisionally determining the reflection characteristic of each pixel of the second light modulation element, and the first light modulation element based on the reflection characteristic provisionally determined in the reflection characteristic provisional determination step and the display data A light propagation characteristic determining step for determining a light propagation characteristic of each of the pixels, and a first control for determining a control value of each pixel of the first light modulation element based on the light propagation characteristic determined in the light propagation characteristic determining step A value determination step, a reflection characteristic determination step for determining a reflection characteristic of each pixel of the second light modulation element based on the light propagation characteristic determined in the light propagation characteristic determination step and the display data, and the reflection characteristic determination step A second control value determining step of determining a control value of each pixel of the second light modulation element based on the reflection characteristic determined in
The image transformation step is applied to any one of the light propagation characteristic determination step, the first control value determination step, the reflection characteristic determination step, and the second control value determination step.
Thereby, an effect equivalent to that of the optical display device of aspect 5 is obtained.

  Here, the reflection characteristic determination step may be any method as long as the reflection characteristic of each pixel of the second light modulation element is determined based on the light propagation characteristic and display data determined in the light propagation characteristic determination step. In addition to the light propagation characteristic itself determined in the light propagation characteristic determination step, calculation or conversion is performed based on the light propagation characteristic determined in the light propagation characteristic determination step, and the second optical modulation is performed based on the calculation result or conversion result. The reflection characteristics of each pixel of the element may be determined. For example, since the control value determined in the first control value determination step is determined based on the light propagation characteristic determined in the light propagation characteristic determination step, the reflection characteristic determination step is the control determined in the first control value determination step. Based on the value and the display data, the reflection characteristic of each pixel of the second light modulation element can be determined.

[Invention 14] Furthermore, the image display method of Invention 14 is the image display method of Invention 12,
The first light modulation element is a light modulation element that determines display resolution;
Further, a light propagation characteristic provisionally determining step for provisionally determining light propagation characteristics of each pixel of the first light modulation element, the light propagation characteristics provisionally determined in the light propagation characteristic provisional determination step, and the display data based on the display data A reflection characteristic determination step for determining a reflection characteristic of each pixel of the two-light modulation element, and a first control for determining a control value of each pixel of the second light modulation element based on the reflection characteristic determined in the reflection characteristic determination step A value determining step; a light propagation characteristic determining step for determining a light propagation characteristic of each pixel of the first light modulation element based on the reflection characteristic determined in the reflection characteristic determination step and the display data; and the light propagation characteristic determination. A second control value determining step for determining a control value of each pixel of the first light modulation element based on the light propagation characteristic determined in the step,
The image transformation step is applied to any of the reflection characteristic determination step, the first control value determination step, the light propagation characteristic determination step, and the second control value determination step.
Thereby, an effect equivalent to that of the optical display device of aspect 6 is obtained.

  Here, the light propagation characteristic determination step may be any method as long as the light propagation characteristic of each pixel of the first light modulation element is determined based on the reflection characteristic determined in the reflection characteristic determination step and the display data. Not only the reflection characteristic itself determined in the reflection characteristic determination step but also the calculation or conversion based on the reflection characteristic determined in the reflection characteristic determination step, and each pixel of the first light modulation element based on the calculation result or conversion result The light propagation characteristics may be determined. For example, since the control value determined in the first control value determination step is determined based on the reflection characteristic determined in the reflection characteristic determination step, the light propagation characteristic determination step is the control value determined in the first control value determination step. Based on the display data, the light propagation characteristics of each pixel of the first light modulation element can be determined.

[Invention 15] Furthermore, the image display method of Invention 15 is the image display method of any one of Inventions 10 to 14,
The second light modulation element is a DMD.
Thereby, an effect equivalent to that of the optical display device of aspect 7 is obtained.

[Invention 16] Furthermore, the image display method of Invention 16 is the image display method of any one of Inventions 10 to 14,
The second light modulation element is a reflective liquid crystal display element.
Thereby, an effect equivalent to that of the optical display device of aspect 8 is obtained.

Embodiments of the present invention will be described below with reference to the drawings. 1 to 16 are diagrams showing an embodiment of a light modulation device and an optical display device, and a light modulation method and an image display method according to the present invention.
In the present embodiment, the light modulation device and the optical display device, and the light modulation method and the image display method according to the present invention are applied to a projection display device 100 as shown in FIG.

First, the configuration of the projection display device 100 will be described with reference to FIG.
FIG. 1 is a block diagram illustrating a hardware configuration of the projection display apparatus 100.
As shown in FIG. 1, the projection display device 100 includes a light source 10, a luminance distribution uniformizing unit 12 that uniformizes a luminance distribution of light incident from the light source 10, and a light incident from the luminance distribution uniforming unit 12. The color modulation unit 14 that modulates the luminances of the RGB three primary colors in the wavelength region, the relay lens 16 that relays the light incident from the color modulation unit 14, and the luminance in the entire wavelength region of the light that is incident from the relay lens 16 The luminance modulation unit 18 and a projection unit 20 that projects light incident from the luminance modulation unit 18 onto a screen (not shown) are configured.

The light source 10 includes a lamp 10a such as a high-pressure mercury lamp and a reflector 10b that reflects light emitted from the lamp 10a.
The color modulation unit 14 includes three transmissive liquid crystal light valves 40R, 40G, and 40B in which a plurality of pixels whose transmittance can be independently controlled are arranged in a matrix, and five field lenses 42R, 42G, and 42B ₁ to. and 42B _3, 2 dichroic mirrors 44a, and 44b, 3 mirrors 46a, 46b, and 46c, is constituted by a dichroic prism 48. First, it lights the dichroic mirror 44a from uniform luminance distribution section 12, as well as spectral red, green and blue RGB3 primary by 44b, via the field lens 42R, 42G, and 42B ₁ ~42B ₃ and mirror 46a~46c The light enters the transmissive liquid crystal light valves 40R to 40B. The luminance of the RGB three primary colors is then modulated by the transmissive liquid crystal light valves 40R to 40B, and the modulated RGB three primary colors are synthesized by the dichroic prism 48 and emitted to the relay lens 16.

  The transmissive liquid crystal light valves 40R to 40B include a glass substrate on which pixel electrodes and switching elements such as thin film transistors and thin film diodes for driving the pixel electrodes are formed in a matrix, and a glass substrate on which a common electrode is formed over the entire surface. This is an active matrix type liquid crystal display element in which a TN liquid crystal is sandwiched between and a polarizing plate is disposed on the outer surface. The transmissive liquid crystal light valves 40R to 40B are in a normally white mode in which a white / bright (transmission) state is applied when no voltage is applied, and a black / dark (non-transmission) state is applied when a voltage is applied, or vice versa. It is driven, and the gradation between light and dark is analog controlled according to the given control value.

The dichroic prism 48 is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X-shaped cross section. With these dielectric multilayer films, RGB three primary colors can be synthesized.
The luminance modulation unit 18 includes a DMD 50 in which a plurality of pixels whose reflectance can be controlled independently is arranged in a matrix and has a higher resolution than the transmissive liquid crystal light valves 40R to 40B, and a TIR prism 52. . First, the light from the relay lens 16 is reflected by the TIR prism 52 and enters the DMD 50, and the luminance of the entire wavelength region of the incident light is modulated by the DMD 50 and reflected. Then, a predetermined component of the reflected light beam is emitted to the projection unit 20 via the TIR prism 52.

  The DMD 50 functions as a mirror to time-control the reflection direction of the light beam, in other words, to perform modulation by time control that switches the light passing state or the light-blocking state. The key is digitally controlled. When each pixel of the DMD 50 is controlled in a predetermined frame unit, for example, if the control is performed so that incident light is reflected toward the projection unit 20 for half the time of one frame, the luminance of the pixel becomes 1/2. Further, since the DMD 50 has a light shielding portion such as a signal line and a driving transistor formed under the reflective pixel electrode, the aperture ratio is large as shown in FIG. 23, and the transmissive liquid crystal light valves 40R to 40B and the relay lens are provided. Even if there is a slight alignment error with respect to 16, the brightness of the display image is not lowered, and moire is not so noticeable.

FIG. 2 is a diagram showing an imaging relationship between the transmissive liquid crystal light valves 40R to 40B and the DMD 50. As shown in FIG.
FIG. 2A schematically shows between the transmissive liquid crystal light valves 40R to 40B and the DMD 50 in the overall configuration shown in FIG. The transmissive liquid crystal light valves 40R to 40B are replaced with one transmissive liquid crystal light valve, and the dichroic prism 48 is omitted.

  A TIR prism 52 is disposed between the relay lens 16 and the DMD 50. The TIR prism 52 is used to improve the contrast characteristics of an optical system using the DMD 50, and is a transmissive liquid crystal light valve. The imaging relationship between 40R to 40B and DMD 50 is not affected. Therefore, if the TIR prism 52 is omitted, the imaging relationship between the transmissive liquid crystal light valves 40R to 40B and the DMD 50 is as shown in FIG. 2B, and the DMD 50 includes the optical axis of the incident light from the relay lens 16, and It is arranged so as to be an off-axis optical system in which the optical axis of light emitted to the projection unit 20 forms a predetermined angle. That is, the DMD 50 is disposed in front of the projection unit 20, and the transmissive liquid crystal light valves 40R to 40B and the relay lens 16 are disposed obliquely with respect to the DMD 50 so that light is incident at a predetermined incident angle. Yes. This is the most suitable arrangement for the light modulation principle of the DMD 50 that performs light modulation by changing the reflection direction of a light ray incident from an oblique direction. Further, the transmissive liquid crystal light valves 40R to 40B are also arranged to be inclined with respect to the optical axis of the relay lens 16 in accordance with Shine-Pluff's law described later.

  FIG. 3 is an explanatory diagram of an imaging relationship between the transmissive liquid crystal light valves 40R to 40B and the DMD 50 by the relay lens 16. In FIG. 3, the three transmissive liquid crystal light valves 40R to 40B are replaced with one transmissive liquid crystal light valve, and the cross dichroic prism 48 is omitted for easy understanding. Also, the relay lens 16 is simplified by a single lens.

  Now, as shown in FIG. 3A, when the transmissive liquid crystal light valves 40R to 40B are arranged perpendicular to the optical axis of the relay lens 16, the transmissive liquid crystal light valve imaged by the relay lens 16 is formed. The image planes of the optical images 40R to 40B are inclined with respect to the DMD 50 plane as indicated by the dotted line. Therefore, the optical images of the transmissive liquid crystal light valves 40R to 40B are blurred and projected on the pixel surface of the DMD 50, and the luminance distribution formed by the transmissive liquid crystal light valves 40R to 40B is accurately represented on the pixel surface of the DMD 50. Can not communicate to.

  In order to eliminate this luminance distribution blur, the transmissive liquid crystal light valves 40R to 40B, the relay lens 16 and the DMD 50 are arranged according to the Shine-Pluff's law. As shown in FIG. 3B, Shine-Proff's law is defined as an extension surface of an object plane (pixel surfaces of transmission type liquid crystal light valves 40R to 40B) and an imaging lens main plane (main plane of relay lens 16). Assuming that the intersection line intersecting with the extension plane is B, the intersection line between the extension plane of the image plane (pixel surface of the DMD 50) and the extension plane of the imaging lens main plane also coincides with B. That is, if the transmissive liquid crystal light valves 40R to 40B, the relay lens 16 and the DMD 50 are arranged according to Shine-Pluff's law, the luminance distribution formed by the transmissive liquid crystal light valves 40R to 40B is transmitted to the pixel surface of the DMD 50 without being blurred. be able to.

FIG. 4 is a diagram showing optical images of the transmissive liquid crystal light valves 40R to 40B.
In the arrangement according to Shine-Pluff's law, the optical image is not blurred but trapezoidal distortion occurs. When the transmission type liquid crystal light valves 40R to 40B form the lattice-like image of FIG. 4A and form an image on the pixel surface of the DMD 50, the image formed on the pixel surface of the DMD 50 is as shown in FIG. ) (Inverted image in which the upper portion in FIG. 4A is enlarged and the lower portion is reduced) is distorted in a trapezoidal shape. However, there is a law in distortion, and the vertical axes parallel to each other in FIG. 4A are angled so as to converge to the point h in FIG. 4B. This point h is called a burnishing point. Specifically, as shown in FIG. 4C, a perpendicular line (relative to the optical axis) set at the image side focal position of the relay lens 16 and a pixel of the DMD 50 It hits the intersection of the extended surfaces. Further, the horizontal axes parallel to each other in FIG. 4A remain parallel to each other in FIG. 4B, but the interval becomes narrower toward the lower side of FIG. 4B.

FIG. 5 is a diagram for explaining the correspondence between the coordinates of the transmissive liquid crystal light valves 40R to 40B and the DMD 50. FIG.
The plane of FIG. 5 is a plane orthogonal to the intersection line B of FIG. As shown in the lower part of FIG. 5, an xyz orthogonal coordinate system is set as the coordinate system of the entire system. The origin is the intersection of the center of the relay lens 16 and the optical axis. The yz plane is included in the plane of FIG. 5, and the z axis takes the DMD 50 side in parallel with the optical axis.

Further, an XYZ orthogonal coordinate system is set as the coordinate system of the transmissive liquid crystal light valves 40R to 40B. The origin is the intersection of the pixel surface of the transmissive liquid crystal light valves 40R to 40B and the optical axis. The YZ plane is included in the plane of FIG. 5, and the XY plane is included in the pixel surfaces of the transmissive liquid crystal light valves 40R to 40B.
Further, an X′-Y′-Z ′ orthogonal coordinate system is set as the coordinate system of the DMD 50. The origin is the intersection of the pixel surface of the DMD 50 and the optical axis. The Y′-Z ′ plane is included in the plane of FIG. 5, and the X′-Y ′ plane is included in the pixel surface of the DMD 50.

The imaging relationship between the transmissive liquid crystal light valves 40R to 40B and the DMD 50 can be expressed by the following expression (3) when expressed based on the coordinate system of FIG.

X ′ = f / (f + z0 + Y · sin θ) · X
Y ′ = cos θ / cos θ ′ · f / (f + z0 + Y · sin θ) · Y (3)

Here, f is the focal length of the relay lens 16, z0 is the distance from the principal point of the relay lens 16 to the transmissive liquid crystal light valves 40R to 40B, and θ is the plane of the transmissive liquid crystal light valves 40R to 40B and the relay lens 16. The angle θ ′ formed by the main plane is the angle formed by the plane of DMD 50 and the main plane of relay lens 16.

Therefore, in order to obtain the originally desired luminance distribution on the pixel surface of the DMD 50, it is necessary to display an image in consideration of trapezoidal distortion in advance on the transmissive liquid crystal light valves 40R to 40B. This can be realized by forming an image subjected to image processing according to the above equation (3) on the transmissive liquid crystal light valves 40R to 40B. This image processing will be described in detail later.
The luminance distribution uniformizing unit 12 includes two fly-eye lenses 12a and 12b, a polarization conversion element 12c, and a condenser lens 12d. Then, the brightness distribution of the light from the light source 10 is made uniform by the fly-eye lenses 12a and 12b, and the uniformed light is polarized by the polarization conversion element 12c in the incident polarization direction of the color modulation light valve to collect the polarized light. The light is condensed by the lens 12 d and emitted to the color modulation unit 14.

For example, the polarization conversion element 12c includes a PBS array and a half-wave plate. The half-wave plate converts incident linearly polarized light into linearly polarized light orthogonal thereto.
FIG. 6 is a diagram illustrating a configuration of the relay lens 16.
The relay lens 16 forms an optical image of each of the transmissive liquid crystal light valves 40R to 40B on the pixel surface of the DMD 50. As shown in FIG. This is an equal-magnification imaging lens composed of a lens group and a rear lens group. The front lens group and the rear lens group are configured by a plurality of convex lenses and one concave lens. However, the shape, size, arrangement interval and number of lenses, telecentricity, magnification, and other lens characteristics can be appropriately changed according to required characteristics, and are not limited to the example of FIG.

FIG. 7 is a diagram illustrating the operating principle of the relay lens 16.
As shown in FIG. 7, the relay lens 16 typically has an equal magnification imaging, so that the optical images of the transmission type liquid crystal light valves 40 </ b> R to 40 </ b> B are inverted and formed on the pixel surface of the DMD 50. Further, since the relay lens 16 is composed of a large number of lenses, the aberration correction is good, and the luminance distribution formed by each of the transmissive liquid crystal light valves 40R to 40B can be accurately transmitted to the DMD 50.

  On the other hand, the projection display device 100 includes a display control device 200 (not shown) that controls the transmissive liquid crystal light valves 40R to 40B and the DMD 50. Hereinafter, the transmissive liquid crystal light valves 40R to 40B are generically referred to as color modulation light valves, and the DMD 50 is generically referred to as a luminance modulation element. Further, in the present embodiment, the luminance modulation element determines the display resolution (the resolution perceived by the observer when the observer views the display image of the projection display device 100).

Next, the configuration of the display control apparatus 200 will be described in detail with reference to FIGS.
FIG. 8 is a block diagram illustrating a hardware configuration of the display control apparatus 200.
As shown in FIG. 8, the display control device 200 reads out from the CPU 70 that controls the calculation and the entire system based on the control program, the ROM 72 that stores the control program of the CPU 70 in a predetermined area, the ROM 72, and the like. It is composed of a RAM 74 for storing data and calculation results required in the calculation process of the CPU 70, and an I / F 78 that mediates input / output of data to / from an external device, and these are used for transferring data. They are connected to each other via a bus 79 which is a signal line so as to be able to exchange data.

The I / F 78 is connected as an external device to a light valve driving device 80 that drives the color modulation light valve and the luminance modulation element, a storage device 82 that stores data, tables, and the like as files, and an external network 199. Are connected to the signal line.
The storage device 82 stores HDR display data.
The HDR display data is image data capable of realizing a high luminance dynamic range that cannot be realized by a conventional image format such as sRGB, and stores pixel values indicating pixel luminance levels for all pixels of the image. Currently, it is used to synthesize CG objects into actual scenery, especially in the CG world. Although there are various image formats, there are many formats in which pixel values are stored in a floating-point format in order to realize a luminance dynamic range higher than a conventional image format such as sRGB. As values to be stored, physical radiance that does not consider human visual characteristics (Radiance = W / (sr · m ² )), or luminance that considers human visual characteristics (luminance = cd / m ² ). It is also a feature that it is a value regarding. In this embodiment, a format in which pixel values indicating radiance levels for each of the three primary colors of RGB are stored as floating point values for one pixel as HDR display data is used. For example, a value of (1.2, 5.4, 2.3) is stored as the pixel value of one pixel.

  The HDR display data is generated based on a HDR image having a high luminance dynamic range and a captured HDR image. However, with current film cameras and digital still cameras, HDR images with a high luminance dynamic range in nature cannot be taken at a time. Therefore, one HDR image is generated from a plurality of photographed images whose exposure is changed by some method. For details of the method for generating HDR display data, see, for example, publicly known document 1 “PEDebevec, J. Malik,“ Recovering High Dynamic Range Radiance Maps from Photographs ”, Proceedings of ACM SIGGRAPH97, pp.367-378 (1997). It is published in.

The storage device 82 stores control value registration tables 400R, 400G, and 400B in which the control values of the color modulation light valves are registered for each color modulation light valve.
FIG. 9 is a diagram illustrating a data structure of the control value registration table 400R.
In the control value registration table 400R, as shown in FIG. 9, one record is registered for each control value of the transmissive liquid crystal light valve 40R. Each record includes a field in which the control value of the transmissive liquid crystal light valve 40R is registered and a field in which the transmittance of the transmissive liquid crystal light valve 40R is registered.

  In the example of FIG. 9, “0” is registered as the control value and “0.004” is registered as the transmittance in the first record. This indicates that when the control value “0” is output to the transmissive liquid crystal light valve 40R, the transmittance of the transmissive liquid crystal light valve 40R is 0.4%. FIG. 9 shows an example in which the number of gradations of the color modulation light valve is 4 bits (0 to 15 values). However, in actuality, there is a record corresponding to the number of gradations of the color modulation light valve. be registered. For example, when the number of gradations is 8 bits, 256 records are registered.

The data structure of the control value registration tables 400G and 400B is not particularly shown, but has the same data structure as the control value registration table 400R. However, the difference from the control value registration table 400R is that the transmittance corresponding to the same control value is different.
Further, the storage device 82 stores a control value registration table 420 in which control values for luminance modulation elements are registered.

FIG. 10 is a diagram illustrating a data structure of the control value registration table 420.
In the control value registration table 420, as shown in FIG. 10, one record is registered for each control value of the luminance modulation element. Each record includes a field in which the control value of the luminance modulation element is registered and a field in which the reflectance of the luminance modulation element is registered.
In the example of FIG. 10, “0” is registered as the control value and “0.003” is registered as the reflectance in the first record. This indicates that when the control value “0” is output to the luminance modulation element, the reflectance of the luminance modulation element is 0.3%. Note that FIG. 10 shows an example in which the number of gradations of the luminance modulation element is 4 bits (0 to 15 values), but in practice, a record corresponding to the number of gradations of the luminance modulation element is registered. The For example, when the number of gradations is 8 bits, 256 records are registered.

In addition, the storage device 82 stores a pixel correspondence table that defines the correspondence between the pixels of the color modulation light valve and the pixels of the luminance modulation element by the above equation (3).
Next, the configuration of the CPU 70 and the processing executed by the CPU 70 will be described.
The CPU 70 includes a microprocessing unit (MPU) or the like, starts a predetermined program stored in a predetermined area of the ROM 72, and executes display control processing shown in the flowchart of FIG. 11 according to the program. .

FIG. 11 is a flowchart showing the display control process.
The display control process is a process of determining control values of the color modulation light valve and the luminance modulation element based on the HDR display data, and driving the color modulation light valve and the luminance modulation element based on the determined control value, When executed in the CPU 70, as shown in FIG. 11, first, the process proceeds to step S100.

In step S100, the HDR display data is read from the storage device 82.
In step S102, the read HDR display data is analyzed, and a histogram of pixel values, a maximum value, a minimum value, an average value, and the like of the luminance level are calculated. This analysis result is for use in automatic image correction such as brightening a dark scene, darkening a scene that is too bright, or coordinating intermediate contrast, or for tone mapping.

Next, the process proceeds to step S104, and tone mapping is performed on the luminance level of the HDR display data to the luminance dynamic range of the projection display device 100 based on the analysis result of step S102.
FIG. 12 is a diagram for explaining tone mapping processing.
As a result of analyzing the HDR display data, it is assumed that the minimum value of the luminance level included in the HDR display data is Smin and the maximum value is Smax. Further, it is assumed that the minimum value of the luminance dynamic range of the projection display apparatus 100 is Dmin and the maximum value is Dmax. In the example of FIG. 12, since Smin is smaller than Dmin and Smax is larger than Dmax, HDR display data cannot be appropriately displayed as it is. Therefore, normalization is performed so that the histogram of Smin to Smax falls within the range of Dmin to Dmax.

Details of tone mapping are disclosed in, for example, publicly known document 2 “F. Drago, K. Myszkowski, T. Annen, N. Chiba,“ Adaptive Logarithmic Mapping For Displaying High Contrast Scenes ”, Eurographics 2003, (2003)”. It is posted.
Next, the process proceeds to step S106, and the HDR image is resized (enlarged or reduced) in accordance with the resolution of the luminance modulation element. At this time, the HDR image is resized while maintaining the aspect ratio of the HDR image. Examples of the resizing method include an average value method, an intermediate value method, and a nearest neighbor method (nearest neighbor method).

Next, the process proceeds to step S108, and based on the luminance level Rp of each pixel of the resized image and the luminance Rs of the light source 10, the light modulation rate Tp is calculated for each pixel of the resized image by the above equation (1).
Next, the process proceeds to step S110, where an initial value (for example, 0.2) is given as the reflectance T2 of each pixel of the luminance modulation element, and the reflectance T2 of each pixel of the luminance modulation element is provisionally determined.

Next, the process proceeds to step S112, and based on the calculated light modulation rate Tp, provisionally determined reflectivity T2 and gain G, the transmittance of the color modulation light valve in units of pixels of the luminance modulation element according to the above equation (2). T1 ′ is calculated.
Next, the process proceeds to step S114, and for each pixel of the color modulation light valve, the weighted average value of the transmittance T1 ′ calculated for the pixel of the luminance modulation element that overlaps the pixel on the optical path is set as the transmittance T1 of the pixel. calculate. Weighting is performed based on the area ratio of overlapping pixels. Also, the pixel correspondence can be obtained by referring to the pixel correspondence table of the storage device 82.

  Next, the process proceeds to step S116, and for each pixel of the color modulation light valve, a control value corresponding to the transmittance T1 calculated for the pixel is read from the control value registration tables 400R to 400B, and the read control value is read from the pixel. Is determined as the control value. In the reading of the control value, the transmittance that most closely approximates the calculated transmittance T1 is searched from the control value registration tables 400R to 400B, and the control value corresponding to the transmittance found by the search is read. This search is performed using, for example, a binary search method, thereby realizing a high-speed search.

  Next, the process proceeds to step S118, and for each pixel of the luminance modulation element, the weighted average value of the transmittance T1 determined for the pixel of the color modulation light valve that overlaps the pixel on the optical path is calculated, and the calculated average value, Based on the light modulation rate Tp and gain G calculated in step S108, the reflectance T2 of the pixel is calculated by the above equation (2). Weighting is performed based on the area ratio of overlapping pixels. Also, the pixel correspondence can be obtained by referring to the pixel correspondence table of the storage device 82.

  Next, the process proceeds to step S120, and for each pixel of the luminance modulation element, a control value corresponding to the reflectance T2 calculated for that pixel is read from the control value registration table 420, and the read control value is the control value for that pixel. Determine as. In reading the control value, the reflectance closest to the calculated reflectance T2 is searched from the control value registration table 420, and the control value corresponding to the reflectance found by the search is read. This search is performed using, for example, a binary search method, thereby realizing a high-speed search.

Next, the process proceeds to step S122, the control values determined in steps S116 and S120 are output to the light valve driving device 80, the color modulation light valve and the luminance modulation element are respectively driven to project a display image, and a series of processes To return to the original process.
Next, the operation of the present embodiment will be described with reference to FIGS.
In the present embodiment, since the color modulation light valve is composed of three transmissive liquid crystal light valves 40R to 40B, the following description is applied to each of the three primary colors RGB. Since all the basic concepts are the same, the description will be made by replacing the three transmissive liquid crystal light valves 40R to 40B with one transmissive liquid crystal light valve for the purpose of avoiding complicated explanation.

In the following, the luminance modulation element has a resolution of 18 horizontal pixels × 12 vertical pixels and a gradation number of 4 bits, and each of the color modulation light valves has a resolution of 15 horizontal pixels × 10 vertical pixels and a 4-bit scale. An explanation will be given taking the case of having a logarithm as an example. Also, the plan views of the luminance modulation element and the color modulation light valve in FIGS. 13 to 16 are all plan views as seen from the light source 10 side, and the optical correspondence between the pixels is based on the following conditions. Shall be calculated.

〔Calculation condition〕
Size of luminance modulation element and color modulation light valve: long side 90, short side 50
The focal length of the relay lens 16: f = 100
The distance between the color modulation light valve and the relay lens: z0 = −50 (refer to FIG. 5, the code corresponding to the z-axis direction of the xyz orthogonal coordinate system with the position of the relay lens 16 as a base point) In this case, the direction of z0 is negative because it is the negative direction of the z-axis)
Inclination of luminance modulation element and color modulation light valve: θ = θ ′ = 20 °
The intersection of the color modulation light valve and the optical axis is set at a position shifted by 6 on the + Y side from the display surface center of the color modulation light valve, and the intersection of the luminance modulation element and the optical axis is the center of the display surface of the luminance modulation element. Match.

In the display control device 200, the HDR display data is read through steps S100 to S104, the read HDR display data is analyzed, and the luminance level of the HDR display data is determined based on the analysis result. Tone-mapped to 100 luminance dynamic range. Next, through step S106, the HDR image is resized in accordance with the resolution of the luminance modulation element.

  Next, through step S108, the light modulation rate Tp is calculated for each pixel of the resized image. For example, the light modulation rate Tp of the pixel p in the resized image is such that the luminance level Rp (R, G, B) of the pixel p is (1.2, 5.4, 2.3) and the luminance Rs (R, R, If (G, B) is (10000, 10000, 10000), then (1.2, 5.4, 2.3) / (10000, 10000, 10000) = (0.00012, 0.00054, 0.00023).

FIG. 13 is a diagram illustrating a case where the reflectance T2 of the luminance modulation element is provisionally determined.
Next, through step S110, the reflectance T2 of each pixel of the luminance modulation element is provisionally determined. Each pixel of the luminance modulation element is numbered as shown in FIG. That is, the number of each pixel is given by 4 digits with the prefix “pd”, the upper 2 digits represent the row number, and the lower 2 digits represent the column number. The row number and the column number are “01” in the upper left row or column of the luminance modulation element. This numbering of pixels is performed in the same manner for the color modulation light valve, but in the case of the color modulation light valve, “pl” is used as a prefix.

The reflectance T2 of these pixels is given an initial value T20 as shown in FIG. 13 (b).
FIG. 14 is a diagram illustrating a case where the transmittance T1 ′ of the color modulation light valve is calculated for each pixel of the luminance modulation element.
Next, through step S112, the transmittance T1 ′ of the color modulation light valve is calculated for each pixel of the luminance modulation element.

When attention is paid to the pixels pd (0101) to pd (0303) at the upper left of the luminance modulation element, the transmittances T1 ′ (0101) to T1 ′ (0303) of the color modulation light valve corresponding thereto are expressed by the above equation (2). When the gain G is “1”, it can be calculated by the following equations (4) to (12). Here, Tp0101 to Tp0303 are the light modulation rates of the display pixels corresponding to the pixels pd (0101) to pd (0303).

T1 ′ (0101) = Tp0101 / T20 (4)
T1 ′ (0102) = Tp0102 / T20 (5)
T1 ′ (0103) = Tp0103 / T20 (6)
T1 ′ (0201) = Tp0201 / T20 (7)
T1 ′ (0202) = Tp0202 / T20 (8)
T1 ′ (0203) = Tp0203 / T20 (9)
T1 ′ (0301) = Tp0301 / T20 (10)
T1 ′ (0302) = Tp0302 / T20 (11)
T1 ′ (0303) = Tp0303 / T20 (12)

Actually calculate using numerical values. When Tp0101 = 0.00012, Tp0102 = 0.05, Tp0103 = 0.02, Tp0201 = 0.01, Tp0202 = 0.03, Tp0203 = 0.005, Tp0301 = 0.009, Tp0302 = 0.035, Tp0303 = 0.0006, T20 = 0.1, the above formula (4) to According to (12), T1 ′ (0101) = 0.0012, T1 ′ (0102) = 0.5, T1 ′ (0103) = 0.2, T1 ′ (0201) = 0.1, T1 ′ (0202) = 0.3, T1 ′ (0203) = 0.05, T1 ′ (0301) = 0.09, T1 ′ (0302) = 0.35, and T1 ′ (0303) = 0.006.

Since the luminance modulation element and the color modulation light valve are in a conjugate relationship of inverted imaging by the relay lens 16, the portion of the color modulation light valve corresponding to the upper left nine pixels of the luminance modulation element is as shown in FIG. It will be located in the lower right.
FIG. 15 is a diagram illustrating a case where the transmittance T1 of each pixel of the color modulation light valve is determined.
Next, through step S114, the transmittance T1 of each pixel of the color modulation light valve is determined.

  Since the luminance modulation element and the color modulation light valve are in a conjugate relationship of inverted imaging by the relay lens 16, and further, the color modulation light valve, the relay lens 16 and the luminance modulation element are arranged according to Shine-Proff's law. The transmittances T1 ′ (0101) to T1 ′ (0303) of the color modulation light valve calculated in units of pixels of the luminance modulation element are actually shown in FIG. 15A on the pixel surface of the color modulation light valve. It corresponds optically to the position. Since such an optical correspondence is defined in the pixel correspondence table according to the above equation (3), it can be easily obtained by referring to the pixel correspondence table. The pixel correspondence table is similarly referred to when determining the reflectance T2.

  The pixel correspondence table can be created by obtaining the optical correspondence between the luminance modulation element and the color modulation light valve using commercially available optical simulation software or the like in addition to the above equation (3). Specifically, the ray tracing is performed from which position on the pixel surface of the color modulation light valve the principal ray passing through the pixel of interest of the luminance modulation element is emitted. By this operation, it is determined which pixel of the color modulation light valve corresponds to the pixel of interest. This operation is performed for all the pixels of the luminance modulation element, and all the optical correspondences are recorded as a pixel correspondence table. If this method is used, the influence of the aberration generated in the relay lens 16 can be taken into consideration, and a more precise optical correspondence can be obtained.

  As shown in FIG. 15B, the pixels of the color modulation light valve are numbered according to the method described above, and the transmittance of the color modulation light valve calculated in units of pixels of the lower right four pixels and the luminance modulation element. FIG. 15C shows an enlarged view of the overlap of T1 ′. Taking the pixel pl (1015) as an example, it overlaps with T1 '(0102) to T1' (0203) intricately. This is because the luminance modulation element and the color modulation light valve have different resolutions and are arranged in accordance with Shine-Pluff's law.

In this case, the overlapping area ratio between the pixel pl (1015) and T1 ′ (0102) to T1 ′ (0203) is T1 ′ (0102): T1 ′ (0103): T1 ′ (0202): T1 ′ (0203). = 216: 403: 10: 11. Therefore, the transmittance T1 (1015) of the pixel pl (1015) can be calculated by the following equation (13).

T1 (1015) = (T1 ′ (0102) × 216 + T1 ′ (0103) × 403 + T1 ′ (0202) × 10 + T1 ′ (0203) × 11) / 640 (13)

Actually calculate using numerical values. When T1 ′ (0102) = 0.5, T1 ′ (0103) = 0.2, T1 ′ (0202) = 0.3, and T1 ′ (0203) = 0.05, the transmittance of the pixel pl (1015) is obtained by the above equation (13). T1 (1015) = 0.3.

Similar to the pixel pl (1015), the transmittance of other pixels of the color modulation light valve can be obtained by the same process by calculating the weighted average value based on the area ratio.
Next, through step S116, for each pixel of the color modulation light valve, a control value corresponding to the transmittance T1 calculated for that pixel is read from the control value registration tables 400R to 400B, and the read control value is read out. Is determined as the control value of the pixel. For example, if T1 (1015) = 0.3 for the R color modulation light valve, referring to the control value registration table 400R, 0.35 is the closest value as shown in FIG. Therefore, “11” is read as the control value of the pixel pl (1015) from the control value registration table 400R.

The transmittance distribution of the color modulation light valve calculated in this way is a transmittance distribution for correcting distortion generated on the pixel surface of the luminance modulation element.
FIG. 16 is a diagram illustrating a case where the reflectance T2 of each pixel of the luminance modulation element is determined.
Next, through step S118, the reflectance T2 of each pixel of the luminance modulation element is determined.
For the same reason as described in FIG. 15A, the transmittance T1 of each pixel of the color modulation light valve optically corresponds to the position shown in FIG. 16A on the pixel surface of the luminance modulation element. It becomes. FIG. 15B is an enlarged view showing the overlapping state of the upper left nine pixels of the luminance modulation element and T1 (0914) to T1 (1015).

Taking the pixel pd (0103) of the luminance modulation element as an example, the transmittances T1 (1014) and T1 (1015) of the color modulation light valve overlap in an intricate manner on the optical path. In this case, the overlapping area ratio of the pixel pd (0103) of the luminance modulation element and the transmittances T1 (1014) and T1 (1015) of the color modulation light valve is T1 (1014): T1 (1015) = 48: 39. It becomes.
Therefore, when attention is paid to the pixel pd (0103), the transmittance T1 (pd0103) of the color modulation light valve corresponding to the pixel pd (0103) can be calculated by the following equation (14). The reflectance T2 (0103) of the pixel pd (0103) can be calculated by the following equation (15) when the gain G is “1”.

T1 (pd0103) = (T1 (1014) × 48 + T1 (1015) × 39) / 87 (14)
T2 (0103) = Tp (0103) / T1 (pd0103) (15)

Actually calculate using numerical values. When T1 (1014) = 0.2 and T1 (1015) = 0.3, T1 (pd0103) = 0.24 and the reflectance of the pixel pd (0103) is T2 (0103) = 0.08 according to the above equation (14).

Similar to the pixel pd (0101), the reflectance of other pixels of the luminance modulation element can be obtained by calculating a weighted average value based on the area ratio.
Next, through step S120, for each pixel of the luminance modulation element, a control value corresponding to the transmittance T2 calculated for the pixel is read from the control value registration table 420, and the read control value is the pixel. Is determined as a control value. For example, when T2 (0103) = 0.08 for the pixel pd (0103) of the luminance modulation element, referring to the control value registration table 420, 0.09 is the closest approximation as shown in FIG. Therefore, “8” is read from the control value registration table 420 as the control value of the pixel pd (0103).

Then, through step S122, the determined control value is output to the light valve driving device 80. Thereby, the color modulation light valve and the luminance modulation element are driven, and an optical image is formed on the pixel surface of the color modulation light valve and the luminance modulation element.
In this manner, in the present embodiment, the light source 10, the dichroic mirrors 44a and 44b that separate the light from the light source 10 into RGB three primary colors, and the light beams that are separated by the dichroic mirrors 44a and 44b are incident respectively. A color modulation light valve, a dichroic prism 48 that synthesizes light from each color modulation light valve, a DMD 50, and a relay lens 16 that forms a combined optical image of the dichroic prism 48 on the pixel surface of the DMD 50; The valve, relay lens 16 and DMD 50 were placed according to Shine-Pluff's law.

Thereby, since the light from the light source 10 is modulated via the luminance modulation element and the color modulation light valve, a relatively high luminance dynamic range and number of gradations can be realized.
Further, since the luminance modulation element is constituted by the DMD 50 having a high aperture ratio, the luminance of the display image can be secured to some extent even if the alignment accuracy between the color modulation light valve and the DMD 50 is not high. Therefore, it is possible to suppress a decrease in the brightness of the display image as compared with the conventional case.

Furthermore, since the image plane of the optical image of the color modulation light valve coincides with the pixel surface of the luminance modulation element, it is possible to suppress blurring of the optical image formed on the pixel surface of the luminance modulation element. Therefore, it is possible to reduce the possibility that the image quality is deteriorated as compared with the conventional case.
Furthermore, since it is not necessary to use a solid laser or a semiconductor laser as a light source, it is possible to reduce the size and increase the brightness of the apparatus as compared with the conventional case.

Further, since the optical image of each color modulation light valve is formed on the pixel surface of the luminance modulation element via the relay lens 16, the optical image of each color modulation light valve is formed on the pixel surface of the luminance modulation element with relatively high accuracy. be able to. Therefore, it is possible to reduce the possibility that the image quality is deteriorated as compared with the conventional case.
Further, in the present embodiment, distortion that corrects distortion generated on the pixel surface of the DMD 50 is applied to an image formed by the color modulation light valve.

As a result, even if the DMD 50 is arranged so as to be an off-axis optical system, an image formed by the color modulation light valve can be imaged on the pixel surface of the DMD 50 with less distortion. High secondary modulation can be performed. Therefore, it is possible to reduce the possibility that the image quality is deteriorated as compared with the conventional case.
Further, in the present embodiment, the transmittance T1 and the reflectance T2 are determined with reference to the pixel correspondence table.

Thereby, it is possible to determine the transmittance T1 and the reflectance T2 relatively easily in consideration of the distortion applied to the image formed by the color modulation light valve.
Furthermore, in the present embodiment, the color modulation light valve is a liquid crystal light valve.
Thereby, since an existing optical component can be used, an increase in cost can be further suppressed.

Furthermore, in the present embodiment, the luminance distribution uniformizing unit 12 that uniformizes the luminance distribution of the light from the light source 10 is provided on the optical path between the light source 10 and the color modulation unit 14.
As a result, the possibility of uneven brightness distribution can be reduced.
Furthermore, in the present embodiment, the luminance distribution uniformizing unit 12 includes a polarization conversion element 12c that polarizes the light from the light source 10 in the incident polarization direction of the color modulation light valve.

As a result, most of the amount of light from the light source 10 is to be modulated by the color modulation light valve, so that the brightness of the display image can be improved.
Further, in the present embodiment, the reflectance T2 of each pixel of the luminance modulation element is provisionally determined, and the transmittance T1 of each pixel of the color modulation light valve is determined based on the provisionally determined reflectance T2 and HDR display data. The control value of each pixel of the color modulation light valve is determined based on the determined transmittance T1, and the reflectance T2 of each pixel of the luminance modulation element is determined based on the determined transmittance T1 and HDR display data. The control value of each pixel of the luminance modulation element is determined based on the reflectance T2.

Thereby, since the reflectance T2 of the luminance modulation element that determines the display resolution is determined later, the influence of the error can be suppressed, and the possibility that the image quality is deteriorated can be reduced.
Furthermore, in the present embodiment, the transmittance T1 ′ of the color modulation light valve is calculated for each pixel of the luminance modulation element based on the provisionally determined reflectance T2 and HDR display data, and based on the calculated transmittance T1 ′. Thus, the transmittance T1 of each pixel of the color modulation light valve is calculated.

  In the case where the color modulation light valve and the luminance modulation element have different resolutions, they are temporarily determined rather than directly calculating the transmittance T1 of each pixel of the color modulation light valve based on the temporarily determined reflectance T2. Processing is easier if the transmittance T1 ′ of the color modulation light valve is calculated for each pixel of the luminance modulation element based on the reflectance T2 and then the transmittance T1 of each pixel of the color modulation light valve is calculated. . Therefore, when the color modulation light valve and the luminance modulation element have different resolutions, the transmittance T1 of each pixel of the color modulation light valve can be calculated relatively easily.

Further, in the present embodiment, for each pixel of the color modulation light valve, the transmittance T1 of the pixel is calculated based on the transmittance T1 ′ calculated for the pixel of the luminance modulation element that overlaps the pixel on the optical path. It is like that.
Thus, when the color modulation light valve and the luminance modulation element have different resolutions, the transmittance T1 of each pixel of the color modulation light valve is changed to the reflectance T2 of the pixel of the luminance modulation element that overlaps the pixel in the optical path. On the other hand, since the value is relatively appropriate, the possibility that the image quality is deteriorated can be further reduced. In addition, the transmittance T1 of each pixel of the color modulation light valve can be calculated more easily.

Furthermore, in this embodiment, for each pixel of the color modulation light valve, the weighted average value of the transmittance T1 ′ calculated for the pixel of the luminance modulation element that overlaps the pixel on the optical path is used as the transmittance T1 of the pixel. It comes to calculate.
Thus, when the color modulation light valve and the luminance modulation element have different resolutions, the transmittance T1 of each pixel of the color modulation light valve is changed to the reflectance T2 of the pixel of the luminance modulation element that overlaps the pixel in the optical path. On the other hand, since the value is more appropriate, the possibility that the image quality is deteriorated can be further reduced. In addition, the transmittance T1 of each pixel of the color modulation light valve can be calculated more easily.

Furthermore, in the present embodiment, for each pixel of the luminance modulation element, the reflectance T2 of the pixel is calculated based on the transmittance T1 determined for the pixel of the color modulation light valve that overlaps the pixel on the optical path. It has become.
As a result, when the color modulation light valve and the luminance modulation element have different resolutions, the reflectance T2 of each pixel of the luminance modulation element becomes the transmittance T1 of the pixel of the color modulation light valve that overlaps the pixel in the optical path. On the other hand, since the value is relatively appropriate, the possibility that the image quality is deteriorated can be further reduced. Further, the reflectance T2 of each pixel of the luminance modulation element can be calculated relatively easily.

Further, in the present embodiment, for each pixel of the luminance modulation element, a weighted average value of the transmittance T1 determined for the pixel of the color modulation light valve that overlaps the pixel on the optical path is calculated, and based on the average value The reflectance T2 of the pixel is calculated.
As a result, when the color modulation light valve and the luminance modulation element have different resolutions, the reflectance T2 of each pixel of the luminance modulation element becomes the transmittance T1 of the pixel of the color modulation light valve that overlaps the pixel in the optical path. On the other hand, since the value is more appropriate, the possibility that the image quality is deteriorated can be further reduced. In addition, the reflectance T2 of each pixel of the luminance modulation element can be calculated more easily.

Furthermore, in this embodiment, a color modulation light valve is used as the first-stage light modulation element, and a luminance modulation element is used as the second-stage light modulation element.
Accordingly, since only one light modulation element needs to be added to the conventional projection display device, the projection display device 100 can be configured relatively easily.
In the above embodiment, the color modulation light valve corresponds to the first light modulation element of the invention 1 to 5, 9 to 13, and the DMD 50 corresponds to the second light modulation of the invention 1 to 5, 7, 9 to 13 or 15. This corresponds to the element or the reflection type light modulation element of the invention 1, 2, 9 or 10. Further, the dichroic mirrors 44a and 44b correspond to the light separating means of the invention 2 or 10, the dichroic prism 48 corresponds to the light combining means of the invention 2 or 10, and step S110 is a reflection characteristic temporary determining means of the invention 5. Or it corresponds to the reflection characteristic provisional determination step of the invention 13.

  Moreover, in the said embodiment, step S112, S114 respond | corresponds to the light propagation characteristic determination means of the invention 5, or the light propagation characteristic determination step of the invention 13, and step S116 is the 1st control value determination means of the invention 5, This corresponds to the first control value determination step of the thirteenth aspect. Step S118 corresponds to the reflection characteristic determining means of the invention 5 or the reflection characteristic determining step of the invention 13, and the step S120 is a second control value determining means of the invention 5 or a second control value determining step of the invention 13. Steps S114 and S118 correspond to the image deformation means of the inventions 3 to 5 or the image deformation steps of the inventions 11 to 13.

In the above embodiment, the TIR prism 52 is provided. However, the present invention is not limited to this, and the TIR prism 52 may be provided as shown in FIG.
FIG. 17 is a diagram showing a case where the projection display apparatus 100 is configured without providing the TIR prism 52.
As shown in FIG. 17, the projection display device 100 includes a light source 10, a luminance distribution uniformizing unit 12, a color modulation unit 14, a relay lens 16, a luminance modulation unit 18, and a projection unit 20.

  The luminance modulation unit 18 includes a DMD 50 in which a plurality of pixels whose reflectance can be controlled independently are arranged in a matrix. The DMD 50 is disposed so as to be an off-axis optical system in which the optical axis of the incident light from the relay lens 16 and the optical axis of the outgoing light to the projection unit 20 form a predetermined angle. That is, the DMD 50 is disposed in front of the projection unit 20, and the transmissive liquid crystal light valves 40R to 40B and the relay lens 16 are disposed obliquely with respect to the DMD 50 so that light is incident at a predetermined incident angle. Yes. Further, the color modulation light valve, the relay lens 16 and the DMD 50 are arranged according to Shine-Pluff's law.

In the above embodiment, the luminance modulation element is configured by the DMD 50. However, instead of this, the luminance modulation element may be configured by a reflective liquid crystal light valve 54 as shown in FIG.
FIG. 18 is a diagram illustrating a case where the projection display device 100 is configured using the reflective liquid crystal light valve 54.

As shown in FIG. 18, the projection display device 100 includes a light source 10, a luminance distribution uniformizing unit 12, a color modulation unit 14, a relay lens 16, a luminance modulation unit 18, and a projection unit 20.
The luminance modulator 18 includes a reflective liquid crystal light valve 54 in which a plurality of pixels whose reflectance T2 can be controlled independently is arranged in a matrix, and a λ / 4 plate for improving the contrast characteristics of the reflective liquid crystal light valve 54 56 and a polarizing plate 58. The reflective liquid crystal light valve 54 is disposed so as to be an off-axis optical system in which the optical axis of the incident light from the relay lens 16 and the optical axis of the outgoing light to the projection unit 20 form a predetermined angle. Further, the color modulation light valve, the relay lens 16 and the reflective liquid crystal light valve 54 are arranged in accordance with Shine-Pluff's law. First, light from the relay lens 16 is incident on the reflective liquid crystal light valve 54 via the λ / 4 plate 56, and the polarization state in the entire wavelength region of the incident light is modulated and reflected by the reflective liquid crystal light valve 54. . Then, the reflected light is incident on the polarizing plate 58 through the λ / 4 plate 56, and a polarization component necessary for image display is emitted to the projection unit 20.

  The reflective liquid crystal light valve 54 is configured by disposing a silicon substrate having a reflective pixel electrode formed in a matrix on the surface and a transparent substrate having a transparent electrode interposed therebetween via a spacer, and enclosing liquid crystal therebetween. Yes. A drive circuit for driving the reflective pixel electrode is also formed on the silicon substrate. An alignment film for aligning liquid crystals in a predetermined direction is formed on the surfaces of these two substrates. The reflective liquid crystal light valve 54 is driven in a normally white mode in which a white / bright (transmission) state is applied when no voltage is applied, and a black / dark (non-transmission) state is applied when a voltage is applied, or vice versa. The gradation between light and dark is analog controlled according to the given control value.

  Similarly to the DMD 50, the reflective liquid crystal light valve 54 has a light-shielding portion such as a signal line and a driving transistor formed under the reflective pixel electrode, so that the aperture ratio is large as shown in FIG. Even if there is a slight alignment error with respect to the light valves 40R to 40B and the relay lens 16, the brightness of the display image is not lowered, and moire is not so noticeable.

  Thus, since the luminance modulation element is constituted by the reflective liquid crystal light valve 54 having a high aperture ratio, the luminance of the display image can be secured to some extent even if the alignment accuracy between the color modulation light valve and the luminance modulation element is not high. Can do. In addition, polarization characteristics can be maintained in light transmission between the color modulation light valve and the luminance modulation element. Therefore, it is possible to suppress a decrease in the brightness of the display image as compared with the conventional case. In addition, as compared with the case where the DMD 50 is used, high definition can be achieved, so that the image quality can be improved and the manufacturing cost can be reduced.

In this case, the reflective liquid crystal light valve 54 corresponds to the second light modulation element of the invention 8 or 16 or the reflective liquid crystal display element of the invention 8 or 16.
In the above embodiment, the transmittance T1 and the reflectance T2 are determined with reference to the pixel correspondence table. However, the present invention is not limited to this, and the color modulation light is referred to with reference to the pixel correspondence table. Any one of the transmittance T1 and the control value of the bulb and the reflectance T2 and the control value of the luminance modulation element can be determined.

  In the above embodiment, the transmissive liquid crystal light valves 40R to 40B are configured using active matrix liquid crystal display elements. However, the present invention is not limited to this, and the transmissive liquid crystal light valves 40R to 40B are passive matrix liquid crystal display elements. A liquid crystal display element and a segment type liquid crystal display element can also be used. The active matrix type liquid crystal display has an advantage that precise gradation display can be performed, and the passive matrix type liquid crystal display element and the segment type liquid crystal display element have an advantage that they can be manufactured at low cost.

  In the above embodiment, since the luminance modulation element is composed of one DMD 50, one control value registration table 420 is prepared, and each pixel of the luminance modulation element is based on the control value registration table 420. However, the present invention is not limited to this, and control value registration tables 420R, 420G, and 420B are prepared for each of the three RGB primary colors, and each pixel of the luminance modulation element is based on the control value registration tables 420R to 420B. The control value can be determined. Since the luminance modulation element modulates the luminance in the entire wavelength region of light, the control value registration table 420 registers the reflectance of light having typical wavelengths. However, the respective reflectances of the RGB three primary colors are not necessarily registered reflectances.

  Therefore, for the luminance modulation element, strictly, the reflectance corresponding to the control value is measured for each of the three primary colors of RGB, and the control value registration tables 420R to 420B are configured. Next, the reflectance T2 of each pixel of the luminance modulation element is determined for each of the three primary colors of RGB, and the reflectance closest to the reflectance T2 calculated for R is retrieved from the control value registration table 420R and retrieved by the retrieval. A control value corresponding to the reflectance is read out. Similarly, the corresponding control value is read from the control value registration tables 420G and 420B based on the reflectance T2 calculated for G and the reflectance T2 calculated for B. Then, the average value of the control values read out for the same pixel of the luminance modulation element is calculated as the control value of that pixel.

As a result, the control value of each pixel of the luminance modulation element becomes a relatively appropriate value with respect to the transmittance for each of the RGB primary colors of the pixel of the color modulation light valve that overlaps the pixel on the optical path, so that the image quality deteriorates. The possibility can be further reduced.
In the above embodiment, the luminance modulation element is configured as a light modulation element that determines display resolution. However, the present invention is not limited to this, and the color modulation light valve is configured as a light modulation element that determines display resolution. You can also. In this case, after determining the reflectance T1 of each pixel of the luminance modulation element (the reflectance of the previously determined light modulation element is T1), the transmittance T2 of each pixel of the color modulation light valve ( The reflectance of the light modulation element to be determined later is T2.) Further, similarly to the above, the control value registration tables 400R to 400B are prepared for each of the three primary colors RGB, and the control value of each pixel of the color modulation light valve is determined based on the control value registration tables 400R to 400B. You can also.

  Specifically, the reflectance T1 of each pixel of the luminance modulation element is determined for each of the RGB three primary colors, and the reflectance closest to the reflectance T1 calculated for R is searched from the control value registration table 400R. A control value corresponding to the retrieved reflectance is read out. Similarly, the corresponding control value is read out from the control value registration tables 400G and 400B based on the reflectance T1 calculated for G and the reflectance T1 calculated for B. Then, the average value of the control values read out for the same pixel of the luminance modulation element is calculated as the control value of that pixel.

As a result, the control value of each pixel of the luminance modulation element becomes a relatively appropriate value with respect to the transmittance for each of the RGB primary colors of the pixel of the color modulation light valve that overlaps the pixel on the optical path, so that the image quality deteriorates. The possibility can be further reduced.
In this case, the color modulation light valve corresponds to the first light modulation element of the invention 6 or 14, and the luminance modulation element corresponds to the second light modulation element of the invention 6 or 14.

  Further, in the above embodiment, the control values of the luminance modulation element and the color modulation light valve are determined based on the HDR display data. However, when normal color 8-bit RGB image data is used, The value of 0 to 255 in the RGB image data is not a physical quantity of luminance but a relative value of 0 to 255. Therefore, in order to display the display device of the present invention based on normal RGB image data, the physical brightness Rp to be displayed or the reflectance Tp of the entire display device or the like must be determined from the normal RGB image. should not.

FIG. 19 is a diagram illustrating a data structure of the input value registration table 440.
Therefore, by using the input value registration table 440 in FIG. 19, it is possible to convert an input value from 0 to 255 of a normal RGB image into Tp such as physical reflectance, and the reflectance of this table. It is possible to easily change the display appearance (gradation characteristics) of a normal RGB image depending on the setting of equal Tp. Since the reflectivity Tp in this table is Tp in the above equation (2), once this value is determined, the same processing as in the above embodiment is performed to transmit the light transmitted through the plurality of light modulation elements. The rate T1 and the reflectance T2 are determined and can be displayed.

FIG. 20 is a diagram illustrating a data structure of the input value registration table 460.
The input value registration table 460 in FIG. 20 uses the luminance level Rp instead of the reflectance Tp. Since the luminance level Rp in this table is Rp in the above equation (1), once this value is determined, the same processing as in the above embodiment is performed thereafter, whereby the transmittance of a plurality of light modulation elements is obtained. T1 and reflectance T2 are determined and can be displayed.

In the above embodiment, for each pixel of the luminance modulation element, the weighted average value of the transmittance T1 determined for the pixel of the color modulation light valve that overlaps the pixel on the optical path is calculated, and based on the average value. However, the present invention is not limited to this, and for each pixel of the luminance modulation element, the control value determined for the pixel of the color modulation light valve that overlaps the pixel on the optical path is also provided. In addition, the transmittance T1 _table corresponding to the control value is read from the control value registration tables 400R to 400B, a weighted average value of the read transmittance T1 _table is calculated, and the reflectance T2 of the pixel is calculated based on the average value. Can also be configured to calculate.

  In the above embodiment, the average value of the transmittance T1 ′ calculated for each of the three primary colors of RGB for the same pixel is calculated as T1 ′ of the pixel. However, the present invention is not limited to this, and the transmittance T1 'Can be calculated as it is for each of the three primary colors of RGB, and in step S114, the average value of the transmittance T1 calculated for each of the three primary colors of RGB for the same pixel can be calculated as T1 of that pixel.

  In the above embodiment, for each pixel of the luminance modulation element, the weighted average value of the transmittance T1 determined for the pixel of the color modulation light valve that overlaps the pixel on the optical path is calculated, and based on the average value. However, the present invention is not limited to this. For each pixel of the luminance modulation element, the transmittance T1 determined for the pixel of the color modulation light valve that overlaps the pixel on the optical path is not limited to this. The maximum value, the minimum value, or the average value may be calculated, and the reflectance T2 of the pixel may be calculated based on the calculated value.

  In the above embodiment, the color modulation light valve is configured by the transmissive liquid crystal light valves 40R to 40B. However, the present invention is not limited to this, and any light modulation element having a plurality of pixels whose light propagation characteristics can be controlled independently. Anything can be used. Here, the light propagation characteristics refer to characteristics that affect light propagation, and include, for example, light transmission characteristics, reflection characteristics, refraction characteristics, and other propagation characteristics.

Further, in the above embodiment, for the sake of simplicity, the light modulation element having a small number of pixels and the number of gradations is used. Processing can be performed in the same manner as in the embodiment.
Further, in the above embodiment, the gain G = 1.0 is set for the sake of simplicity, but the gain G = 1.0 is not obtained depending on the hardware configuration. Further, when considering the actual calculation cost, it is better to register the control value, the reflectance and the like in the control value registration table in a manner including the influence of the gain G.

Further, in the above embodiment, the case where the control program stored in advance in the ROM 72 is executed when executing the processing shown in the flowchart of FIG. 11 is described, but the present invention is not limited to this, and these procedures are shown. The program may be read from the storage medium storing the program into the RAM 74 and executed.
Here, the storage medium is a semiconductor storage medium such as RAM or ROM, a magnetic storage type storage medium such as FD or HD, an optical reading type storage medium such as CD, CDV, LD, or DVD, or a magnetic storage type such as MO. / Optical reading type storage media, including any storage media that can be read by a computer regardless of electronic, magnetic, optical, or other reading methods.

  In the above embodiment, the light modulation device and the optical display device, and the light modulation method and the image display method according to the present invention are applied to the projection display device 100 as shown in FIG. The present invention is not limited, and can be applied to other cases without departing from the gist of the present invention.

2 is a block diagram showing a hardware configuration of a projection display apparatus 100. FIG. It is a figure which shows the imaging relationship of the transmissive | pervious liquid crystal light valves 40R-40B and DMD50. It is explanatory drawing of the imaging relationship of the transmissive | pervious liquid crystal light valves 40R-40B and DMD50 by the relay lens 16. FIG. It is a figure which shows the optical image of the transmissive | pervious liquid crystal light valve 40R-40B. It is a figure explaining the correspondence of the coordinates of transmission type liquid crystal light valves 40R-40B and DMD50. 2 is a diagram illustrating a configuration of a relay lens 16. FIG. FIG. 4 is a diagram illustrating an operation principle of the relay lens 16. 3 is a block diagram illustrating a hardware configuration of a display control device 200. FIG. It is a figure which shows the data structure of the control value registration table 400R. It is a figure which shows the data structure of the control value registration table. It is a flowchart which shows a display control process. It is a figure for demonstrating a tone mapping process. It is a figure which shows the case where the reflectance T2 of a luminance modulation element is provisionally determined. It is a figure which shows the case where the transmittance | permeability T1 'of a color modulation light valve is calculated per pixel of a luminance modulation element. It is a figure which shows the case where the transmittance | permeability T1 of each pixel of a color modulation light valve is determined. It is a figure which shows the case where the reflectance T2 of each pixel of a luminance modulation element is determined. It is a figure which shows the case where the projection type display apparatus 100 is comprised without providing the TIR prism 52. FIG. It is a figure which shows the case where the projection type display apparatus 100 is comprised using the reflection type liquid crystal light valve 54. FIG. It is a figure which shows the data structure of the input value registration table. It is a figure which shows the data structure of the input value registration table 460. It is a figure which shows the pixel surface of each pixel of a transmissive liquid crystal light valve. It is a figure which shows the structure of the optical path of the 1st light modulation element in a projection type display apparatus of patent document 1, and a 2nd light modulation element. It is a figure which shows the pixel surface of each pixel of a reflection type light modulation element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Projection type display apparatus, 10 ... Light source, 10a ... Lamp, 10b ... Reflector, 12 ... Luminance distribution equalization part, 12a, 12b ... Fly eye lens, 12c ... Polarization conversion element, 12d ... Condensing lens, 14 ... Color modulation unit, 40R to 40B, 40RB ... transmissive liquid crystal light _{valves, 42R, 42G, 42B 1 ~42B} 3, 42RB ... field lenses, 44a, 44b ... dichroic mirror, 46a through 46c ... mirror, 48 ... dichroic prism, 16 ... Relay lens, 18 ... Brightness modulation unit, 50 ... DMD, 52 ... TIR prism, 54 ... Reflective liquid crystal light valve, 56 ... λ / 4 plate, 58 ... Polarizing plate, 20 ... Projection unit, 70 ... CPU, 72 ... ROM 74 ... RAM, 78 ... I / F, 79 ... Bus, 80 ... Light valve driving device, 82 ... Memory Location, 199 ... network, 400R~400G, 420,420R~420G ... control value registration table 440, 460 ... input value registration table

Claims (10)

A first light modulation element; a second light modulation element; and a relay lens that forms an optical image of the first light modulation element on a light receiving surface of the second light modulation element. An apparatus for modulating light from a light source via the second light modulation element,
The second light modulation element is constituted by a reflection type light modulation element,
The light modulation device, wherein the first light modulation element, the relay lens, and the second light modulation element are arranged in accordance with Shine-Pluff's law. A light source, a light separating unit that separates light from the light source into a plurality of different specific wavelength regions, a plurality of first light modulation elements that respectively enter the light separated by the light separating unit, and the first A light combining means for combining light from the light modulation elements; a second light modulation element; and a relay lens for forming a combined optical image of the light combination means on a light receiving surface of the second light modulation element. An apparatus for displaying an image by modulating light from the light source via one light modulation element and the second light modulation element,
The second light modulation element is constituted by a reflection type light modulation element,
An optical display device, wherein each of the first light modulation elements, the relay lens, and the second light modulation element is arranged in accordance with Shine-Pruff's law. In claim 2,
The optical axis of the incident light incident on the second light modulation element via the first light modulation element, and the emitted light reflected from the second light modulation element and emitted from the second light modulation element An optical display device comprising: an image deforming unit that applies a distortion corresponding to a predetermined angle formed by the optical axis of the image to the image formed by each of the first light modulation elements. In claim 3,
The first light modulation element is a light modulation element having a plurality of pixels capable of independently controlling light propagation characteristics;
The second light modulation element is a light modulation element having a plurality of pixels capable of independently controlling light reflection characteristics;
The image deforming means is based on a pixel correspondence table and display data defining a correspondence relationship between the pixels of the first light modulation element and the pixels of the second light modulation element in consideration of distortion according to the predetermined angle. An optical display device, wherein one of a light propagation characteristic and a control value of the first light modulation element, and a reflection characteristic and a control value of the second light modulation element are determined. In claim 4,
The second light modulation element is a light modulation element that determines display resolution;
Further, a reflection characteristic temporary determination unit that temporarily determines the reflection characteristic of each pixel of the second light modulation element, the first light modulation element based on the reflection characteristic temporarily determined by the reflection characteristic temporary determination unit and the display data A light propagation characteristic determining means for determining a light propagation characteristic of each pixel of the first and a first control for determining a control value of each pixel of the first light modulation element based on the light propagation characteristic determined by the light propagation characteristic determining means Value determining means; reflection characteristic determining means for determining the reflection characteristics of each pixel of the second light modulation element based on the light propagation characteristics determined by the light propagation characteristic determining means and the display data; and the reflection characteristic determining means Second control value determining means for determining a control value of each pixel of the second light modulation element based on the reflection characteristic determined in
An optical display device, wherein the image deformation means is applied to any one of the light propagation characteristic determination means, the first control value determination means, the reflection characteristic determination means, and the second control value determination means. In claim 4,
The first light modulation element is a light modulation element that determines display resolution;
Further, a light propagation characteristic provisionally determining unit that provisionally determines a light propagation characteristic of each pixel of the first light modulation element, the light propagation characteristic provisionally determined by the light propagation characteristic provisional determination unit, and the display data Reflection characteristic determining means for determining the reflection characteristic of each pixel of the two-light modulation element, and first control for determining a control value of each pixel of the second light modulation element based on the reflection characteristic determined by the reflection characteristic determination means Value determining means, light propagation characteristic determining means for determining light propagation characteristics of each pixel of the first light modulation element based on the reflection characteristics determined by the reflection characteristic determining means and the display data, and the light propagation characteristic determination Second control value determining means for determining a control value of each pixel of the first light modulation element based on the light propagation characteristic determined by the means,
An optical display device, wherein the image deformation means is applied to any one of the reflection characteristic determination means, the first control value determination means, the light propagation characteristic determination means, and the second control value determination means. In any one of Claims 2 thru | or 6,
An optical display device, wherein the second light modulation element is constituted by DMD. In any one of Claims 2 thru | or 6,
An optical display device, wherein the second light modulation element is constituted by a reflective liquid crystal display element. A first modulation step for modulating light from the light source via the first light modulation element, and an optical for forming an optical image of the first light modulation element on the light receiving surface of the second light modulation element via the relay lens. A method of modulating light from the light source, comprising: an image forming step; and a secondary modulation step of modulating light from the first light modulation element via the second light modulation element,
The second light modulation element is a reflective light modulation element;
A light modulation method, wherein the first light modulation element, the relay lens, and the second light modulation element are arranged according to Shine-Pluff's law. A light separation step for separating the light from the light source through a light separation means for separating the light into a plurality of different specific wavelength regions, and for each separated light from the light separation means, through the first light modulation element A first modulation step for modulating the separated light, a light synthesis step for synthesizing the separated lights from the first light modulation elements via light synthesis means for synthesizing the light, and a light synthesis means via a relay lens. An optical image forming step of forming a combined optical image on the light receiving surface of the second light modulation element; and a second modulation step of modulating light from the light combining means via the second light modulation element; A method of displaying an image by modulating light from the light source,
The second light modulation element is a reflective light modulation element;
An image display method, wherein each of the first light modulation elements, the relay lens, and the second light modulation element is arranged according to Shine-Pruff's law.

Images