JP5391543B2 - Projection device - Google Patents

Description

  The present invention relates to a projection apparatus.

  A projection apparatus having a reflective liquid crystal element and a polarization separation element is known (see Patent Document 1).

JP 2001-215613 A

  When the size of the polarization separating element is large, it becomes an obstacle to downsizing the projection apparatus.

A projection apparatus according to a first aspect of the present invention is a reflective modulation element that modulates light from a light source, guides the light from the light source to the reflective modulation element, and modulates the light modulated by the reflective modulation element to a projection optical system. The first optical system that guides and deflects the light beam incident on the outer edge portion of the reflective modulation element in a direction approaching the optical axis, while the light beam incident on the other region excluding the outer edge portion is substantially parallel to the optical axis. Of the light from the second optical system to be advanced and the light from the light source, the light beam incident on the outer edge portion of the reflective modulation element is deflected in a direction away from the optical axis, and incident on the other region excluding the outer edge portion. And a third optical system that deflects the luminous flux to be substantially parallel to the optical axis, and the second optical system reflects the luminous flux deflected away from the optical axis by the third optical system on the inner surface. While moving in a direction approaching the optical axis, the first And wherein the substantially be advanced in parallel to approximately parallel to deflected light flux and the optical axis and the optical axis by the optical system.
According to a sixth aspect of the present invention, there is provided a projection apparatus for modulating a light from a light source, and a direction of separating a light beam incident on at least an outer edge region of the reflective modulation element from an optical axis out of the light from the light source. A first optical system that deflects at least a light beam incident on the central region of the reflection type modulation element substantially parallel to the optical axis, and guides light from the light source to the reflection type modulation element. The light modulated by the type modulation element is guided to the projection optical system, and the light beam deflected in the direction away from the optical axis by the first optical system is reflected on the inner surface and proceeds in the direction closer to the optical axis. And a second optical system for causing a light beam deflected substantially parallel to the optical axis by one optical system to travel substantially parallel to the optical axis.

  According to the present invention, it is possible to reduce the size of a projection apparatus using a reflective modulation element.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating the configuration of the optical system of the projection apparatus according to the first embodiment of the invention. In FIG. 1, the optical system of the projection apparatus includes an LED (light emitting diode) light source 10 that emits white light, a condensing optical system 11, a polarization beam splitter (hereinafter referred to as PBS) 12, a liquid crystal panel 13, and a projection lens. 14. The liquid crystal panel 13 is composed of a reflective liquid crystal.

  A drive current is supplied to the LED light source 10 from a projection control circuit (not shown). The LED light source 10 emits light with brightness according to the supply current. The condensing optical system 11 makes the light from the LED light source 10 substantially parallel light, and enters the PBS 12 after passing through the pre-polarizing plate. In the present embodiment, a P-polarized component is incident on the PBS 12. The PBS 12 illuminates the liquid crystal panel 13 by transmitting an incident light beam that is a P-polarized component at the polarization separation unit 12a.

  A liquid crystal panel drive signal corresponding to an image to be projected is supplied to the liquid crystal panel 13 from a projection control circuit (not shown). The liquid crystal panel 13 is composed of a plurality of pixels on which red, green, and blue filters are formed, and generates a color image by the supplied drive signal. Specifically, a voltage corresponding to an image signal (liquid crystal panel drive signal) is applied to the liquid crystal layer for each pixel. In the liquid crystal layer to which a voltage is applied, the arrangement of liquid crystal molecules changes, and the polarization direction of light passing through the liquid crystal layer changes.

  When the light transmitted through the liquid crystal layer of the liquid crystal panel 13 enters the liquid crystal panel 13, the light travels leftward in FIG. 1 after being reflected by the reflective surface of the liquid crystal panel 13, and then travels rightward through the liquid crystal layer. Then, the light is emitted from the liquid crystal panel 13 and incident on the PBS 12 again. Since the liquid crystal layer to which the voltage is applied functions as a phase plate, the S-polarized light from the white pixel and the P-polarized light from the black pixel are mixed in the light incident on the PBS 12 again.

  The PBS 12 reflects only the modulated light that is the S-polarized component of the re-incident light beam by the polarization separation unit 12a, and emits it as projection light toward the upper projection lens 14 in FIG. Thereby, a modulated image is generated. The P-polarized component light re-entered into the PBS 12 is transmitted to the LED light source 10 side by the polarization separation unit 12a and discarded.

  FIG. 2 is an enlarged view of the LED light source 10 and the condensing optical system 11 described above. The condensing optical system 11 is composed of a refractive optical system having different powers in the central portion and the peripheral portion. Thereby, the condensing optical system 11 causes the parallel light beam Lc to enter the central portion of the PBS 12 and the spread light beam La to enter the peripheral portion of the PBS 12. The parallel light beam Lc travels parallel to the optical axis Ax, and the spreading light beam La travels away from the optical axis Ax.

  In FIG. 1, the light beam La incident on the outer edge of the PBS 12 is substantially outward (away from the optical axis Ax). The light beam La is totally reflected by the inner surface of the PBS 12 in the PBS 12 and illuminates the outer edge of the liquid crystal panel 13 as a light beam Lb that is substantially inward (approaching the optical axis Ax). Note that the light beam incident on other regions (including the central portion) except for the outer edge portion of the PBS 12 is parallel to the optical axis Ax. This parallel light beam travels in parallel in the PBS 12 and illuminates other regions (including the central portion) except for the outer edge portion of the liquid crystal panel 13.

  The actual illumination light (and modulated light) has variations in the angle that travels in the PBS 12. By controlling the luminous flux traveling along the outer edge of the PBS 12 to travel substantially inward, even if the traveling angle of illumination light (and modulated light) traveling through the outer edge of the PBS 12 varies, at least outward It can be deflected so that it does not become.

  The PBS 12 is configured in a cubic shape. When the aspect ratio of the effective pixel area by the liquid crystal panel 13 is different from 1: 1 (for example, horizontal 16: vertical 9), the long side direction of the effective pixel area of the liquid crystal panel 13 is matched with the vertical direction in FIG. That is, FIG. 1 shows the long side of the liquid crystal panel 13. The size of the PBS 12 is at least larger than the size of the long side of the effective pixel area of the liquid crystal panel 13.

  In this description, the inner surface where the PBS 12 totally reflects the outward light beam La is the inner side of the surface corresponding to the short side of the liquid crystal panel 13 among the six surfaces of the PBS 12.

According to the first embodiment described above, the following operational effects can be obtained.
(1) The light flux traveling on the outer edge of the PBS 12 was controlled so as to travel substantially inward. Illumination light (and modulated light) traveling on the outer edge of the PBS 12 can be deflected so as not to face outward (at least in parallel with the inner surface of the PBS 12). As a result, an unnecessary image outside the projected image on the screen 30 (so-called (Ghost image) can be prevented from being projected.

(2) One cause of the ghost image is the presence of light that is emitted as outward light from the PBS 12 and illuminates the liquid crystal panel 13. When the outward modulated light is emitted from the liquid crystal panel 13 illuminated with the outward illumination light, and this modulated light is reflected by the inner surface of the PBS 12 in the PBS 12, a ghost image is generated. In order to avoid this influence, it is one measure to make the size of the PBS 12 sufficiently larger than the size of the liquid crystal panel 13, but increasing the size of the PBS 12 increases the cost and hinders the downsizing of the projection apparatus. With the configuration (1), it is not necessary to increase the size of the PBS 12 in order to eliminate the ghost image, and it is possible to reduce the size and cost.

(3) The PBS 12 is generally configured by joining two right-angle prisms with the polarization separation unit 12a interposed therebetween. Since all three surfaces of the right-angle prism are mirror-finished, the surfaces corresponding to the four sides of the quadrangle indicating the PBS 12 in FIG. 1 are all mirror-treated surfaces. Therefore, after the right angle prism is joined and the PBS 12 is configured, the PBS 12 does not need to be subjected to a mirror surface treatment so as to be totally reflected on the inner surface of the PBS 12.

(Second embodiment)
FIG. 3 is a diagram illustrating the configuration of the optical system of the projection apparatus according to the second embodiment of the invention. With respect to the light from the LED light source (not shown), the parallel light beam Lc is spread to the central portion of the PBS 12 and the light flux La is incident to the peripheral portion of the PBS 12 by the same condensing optical system as in the first embodiment. Same as 1. In the second embodiment, the pre-polarizing plate is installed so that the S-polarized component is incident on the PBS 12. The PBS 12 reflects the incident light beam, which is an S-polarized component, in the polarization separation unit 12a to illuminate the liquid crystal panel 13.

  When the light transmitted through the liquid crystal layer of the liquid crystal panel 13 enters the liquid crystal panel 13, the light travels down the liquid crystal layer in FIG. 3 and is reflected by the reflective surface of the liquid crystal panel 13 and then travels upward through the liquid crystal layer. Then, the light is emitted from the liquid crystal panel 13 and incident on the PBS 12 again. Since the liquid crystal layer to which the voltage is applied functions as a phase plate, the P-polarized light from the white pixel and the S-polarized light from the black pixel are mixed in the light incident on the PBS 12 again.

  The PBS 12 transmits only the modulated light, which is a P-polarized component, of the re-incident light beam through the polarization separation unit 12a and emits it as projection light toward the upper projection lens 14 in FIG. Thereby, a modulated image is generated. The S-polarized component light re-entering the PBS 12 is reflected by the polarization separation unit 12a toward the LED light source 10 and discarded.

  In FIG. 3, the light beam La incident on the outer edge of the PBS 12 is substantially outward (direction away from the optical axis). The luminous flux La is totally reflected by the inner surface of the PBS 12 in the PBS 12 and illuminates the outer edge portion of the liquid crystal panel 13 as a luminous flux Lb that is substantially inward (approaching the optical axis). Note that the light beam incident on other regions (including the central portion) except for the outer edge portion of the PBS 12 is parallel to the optical axis. This parallel light beam travels in parallel in the PBS 12 and illuminates other regions (including the central portion) except for the outer edge portion of the liquid crystal panel 13.

  According to the second embodiment described above, as in the first embodiment, since the light beam traveling through the outer edge portion of the PBS 12 is controlled to travel substantially inward, the illumination traveling through the outer edge portion of the PBS 12 is performed. Light (and modulated light) is deflected so that it does not face outward (at least parallel to the inner surface of PBS 12). As a result, the ghost image to the outside of the projected image can be eliminated without making the PBS 12 sufficiently larger than the liquid crystal panel 13 in order to eliminate the ghost image.

(Third embodiment)
Instead of an LED (light emitting diode) light source that emits white light, an LED light source that emits light of each color of RGB may be provided. FIG. 4 is a diagram illustrating the configuration of the optical system of the projection apparatus according to the third embodiment of the invention. In FIG. 4, the same components as those in FIG.

  With respect to light from an R-color LED light source (not shown), a parallel light beam from the lower surface side of the dichroic prism 15 to the center of the dichroic prism 15 is converted into a light beam from the dichroic prism 15 by the same condensing optical system as in the first embodiment. The light beam La spreads to the periphery and is incident on each of them (light source light (R)).

  With respect to light from a G-color LED light source (not shown), a parallel light beam from the right surface side of the dichroic prism 15 to the center of the dichroic prism 15 is converted into a light beam from the dichroic prism 15 by the same condensing optical system as in the first embodiment. The light beam La spreads to the peripheral part and enters each of them (light source light (G)).

  With respect to light from a B-color LED light source (not shown), a collimated light beam from the upper surface side of the dichroic prism 15 to the center of the dichroic prism 15 is converted into a parallel light beam by The light beam La spreads to the peripheral part and is incident thereon (light source light (B)).

  The dichroic prism 15 bends the R color light to the left side by the filter film 15a and emits it to the PBS 12. Further, the dichroic prism 15 bends the B color light to the left side by the filter film 15b and emits it to the PBS 12. The dichroic prism 15 further transmits the G color light and emits it to the PBS 12.

  A projection control circuit (not shown) sequentially supplies drive current to the R color LED light source, the G color LED light source, and the B color LED light source so as to emit light sequentially in color. The projection control circuit (not shown) further supplies a liquid crystal panel drive signal corresponding to the image of each color to be projected to the liquid crystal panel 13B in synchronization with the color sequential light emission. As a result, RGB color projection images generated in a time-division manner by the monochrome liquid crystal panel 13 </ b> B are field-synthesized, and the observer observes the color projection image on the screen 30.

  In FIG. 4, the light beam La incident on the outer edge of the dichroic prism 15 is substantially outward (in a direction away from the optical axis). This light beam La is totally reflected by the inner surface of the dichroic prism 15 in the dichroic prism 15 and illuminates the outer edge portion of the liquid crystal panel 13B through the PBS 12 as a light beam Lb that is substantially inward (approaching the optical axis). Note that the light beam incident on other regions (including the central portion) excluding the outer edge portion of the dichroic prism 15 is parallel to the optical axis. This parallel light beam travels in parallel in the dichroic prism 15 and the PBS 12 and illuminates other regions (including the central portion) except for the outer edge portion of the liquid crystal panel 13B.

  According to the third embodiment described above, the dichroic prism is controlled so that the light beam traveling along the outer edge of the dichroic prism 15 (and PBS 12) travels substantially inward as in the first embodiment. The illumination light traveling on the outer edge of 15 (and PBS 12) and the modulated light traveling on PBS 12 are deflected so as not to face outward (at least parallel to the inner surface of PBS 12). As a result, the ghost image to the outside of the projected image can be eliminated without making the PBS 12 and the dichroic prism 15 sufficiently larger than the liquid crystal panel 13B in order to eliminate the ghost image.

(Modification 1)
In the above description, the condensing optical system 11 is constituted by a refractive optical system, but may be constituted by a reflective optical system 11B having a predetermined reflecting surface. FIG. 5 is an enlarged view of the LED light source 10 and the reflective optical system 11B in this case. The reflection optical system 11B receives a light beam Lc parallel to the optical axis Ax at the central portion of the PBS 12 (FIG. 1), and a spreading light beam La away from the optical axis Ax at the peripheral portion of the PBS 12 (FIG. 1). Let

(Modification 2)
In the above description, a single-plate type configuration having one liquid crystal panel is exemplified, but the light source light from the R color LED light source, the G color LED light source, and the B color LED light source is individually modulated. The present invention can also be applied to a three-plate configuration including an R color liquid crystal panel, a G color liquid crystal panel, and a B color liquid crystal panel.

  The above description is merely an example, and is not limited to the configuration of the above embodiment.

It is a figure which illustrates the structure of the optical system of the projection apparatus by 1st embodiment of this invention. It is an enlarged view of a LED light source and a condensing optical system. It is a figure which illustrates the structure of the optical system of the projection apparatus by 2nd embodiment of this invention. It is a figure which illustrates the structure of the optical system of the projection apparatus by 3rd embodiment of this invention. It is an enlarged view of a LED light source and a reflective optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... LED light source 11 ... Condensing optical system 11B ... Reflective optical system 12 ... PBS
13, 13B ... Liquid crystal panel 14 ... Projection lens 15 ... Dichroic prism Ax ... Optical axis La ... Outward light flux Lb ... Inward light flux

Claims (7)

A reflective modulation element for modulating light from the light source;
A first optical system that guides light from the light source to the reflective modulation element and guides modulated light from the reflective modulation element to a projection optical system;
A second optical system that deflects the light beam incident on the outer edge portion of the reflective modulation element in a direction approaching the optical axis, and causes the light beam incident on another region other than the outer edge portion to travel substantially parallel to the optical axis; ,
Of the light from the light source, the light beam incident on the outer edge portion of the reflective modulation element is deflected in a direction away from the optical axis, while the light beam incident on the other region excluding the outer edge portion is substantially the same as the optical axis. A third optical system that deflects in parallel,
The second optical system reflects a light beam deflected in a direction away from the optical axis by the third optical system and advances the light beam in a direction to approach the optical axis, while moving the optical axis by the third optical system. And a light beam that is deflected substantially parallel to the light axis and travels substantially parallel to the optical axis. The projection device according to claim 1,
The projection apparatus, wherein the second optical system and the first optical system are configured by a polarization separation prism. The projection device according to claim 1,
It further comprises a multiplexing optical system that combines light from a plurality of light sources having different emission colors,
The reflective modulation element modulates light combined by the combining optical system,
The third optical system is provided for each of the plurality of light sources,
The second optical system is constituted by the multiplexing optical system,
The projection apparatus, wherein the first optical system includes a polarization separation element. The projection apparatus according to claim 3 .
The inner surface where the second optical system reflects the light beam deflected away from the optical axis corresponds to the shorter side of the reflective modulation element among the surfaces constituting the polarization separation element or the multiplexing optical system. A projection device characterized by being inside a surface to be projected. The projection apparatus according to claim 4, wherein
A projection apparatus, wherein an outer surface of the inner surface is mirror-finished. A reflective modulation element for modulating light from the light source;
Of the light from the light source, at least the light beam incident on the outer edge region of the reflective modulation element is deflected away from the optical axis, and at least the light beam incident on the central region of the reflection modulation element is the optical axis. A first optical system that deflects substantially parallel;
The light from the light source is guided to the reflective modulation element, the modulated light by the reflective modulation element is guided to the projection optical system, and the light beam deflected away from the optical axis by the first optical system is reflected on the inner surface. A second optical system that reflects and travels in a direction approaching the optical axis, and travels a light beam deflected substantially parallel to the optical axis by the first optical system and travels substantially parallel to the optical axis. Projection device characterized. The projection apparatus according to claim 6, wherein
The first optical system deflects a light beam incident on the outer edge region of the reflective modulation element, out of the light from the light source, in a direction away from the optical axis, and enters the other region excluding the outer edge region. A projection apparatus for deflecting a light beam substantially parallel to the optical axis.

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