JPS6135481A - Projection type display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a projection type display device that projects an image onto a screen using an optical system. More specifically, the present invention relates to a projection type display device that projects a display image composed of pixels in a matrix onto a screen.

[Prior art]

In recent years, there has been an increasing demand for display devices larger than CRTs, and various large display devices have been developed and marketed. One of these is a display device that magnifies and projects an image made up of pixels arranged in a matrix. FIG. 2 shows the configuration of a projection display device using an LCD (liquid crystal display device) as an image forming means. The LCDI has a matrix of pixels, and forms an original image by controlling the transmittance of each pixel using an external signal. This original image is projected onto the screen 8 by the projection optical system 2.
An image is formed on the image and displayed.

The LCD 1 may be of an X-Y matrix type, an active matrix type, or the like. In addition, as an image forming means, other matrix type optical modulators and light emitting type optical modulators, IJ display devices (
LED, etc.) can also be used.

However, the resolution of such projection display devices is limited by the original image, and in order to increase the resolution, it is necessary to increase the size of the original image and increase the number of pixels, or to increase the density by reducing the pixels. It is. In the former method of enlarging the original image, the manufacturing cost of the display device is high. Even if a plurality of display devices are arranged side by side, it is difficult to eliminate discontinuities in the connected portions of the resulting projected images. On the other hand, the latter high density has a lower limit depending on the mounting and manufacturing process of the display device and external circuit. At present, the lower limit is several tens of micrometers.

In this way, the size and pixel pitch are determined by cost, manufacturing availability, and the number of lines that can be driven, and there is a limit to how high the resolution of the original image can be improved.

[Purpose of the invention]

An object of the present invention is to obtain a high-resolution projection display without increasing the resolution of the original image forming panel. Another goal is to achieve high-resolution, full-color display.

[Summary of the invention]

In the present invention, a plurality of original images consisting of pixels arranged in a matrix and having the same pitch are projected by displacing them by a fraction of a pixel according to a specific arrangement rule to obtain a composite image.

Here, the pixels forming the original image may have different sizes, but must have the same pitch. It is assumed that the display information is sampled according to specific rules and decomposed into a plurality of original images. Interlace, television signals, etc. are examples. Next, a plurality of original images are projected so as to have displacements according to the above-mentioned regularity, and a complete image is reproduced. Furthermore, by combining original images compatible with color display, a high-resolution color display device can be obtained.

〔Example〕

Example 1 Example 1 uses a TPT (thin film transistor) matrix liquid crystal panel (hereinafter referred to as TFTLCD) as a display device for forming an original image.
This is a projection television device that uses The liquid crystal display mode is twisted nematic 4-liquid crystal field effect (hereinafter referred to as FETN), scattering effect (DSM)
), guest-host effect (GH), etc. In this example, the E'1ltTN mode was used.

Furthermore, matrix driving using TPT was selected in order to improve the optical light pulp performance. Therefore, there are many problems even if other matrix type drive methods are used. The configuration of this embodiment is shown in FIG.

The light source is arranged in orthogonal directions [a two-series O condenser lens 4 and a condenser T-mirror 5 are provided to obtain two illumination luminous fluxes from one light source 6 in order to increase the utilization efficiency of the light source light. The direction of this illumination light is changed by mirror 7, and the TF
input to TLCDg.

The light modulated by the TFTLCD is imaged onto the ζ screen by the projection lens 9. Note that 10 is a correction lens for correcting keystone distortion caused by projection. In the example of the NTE'c system, a television signal is 525 in the vertical direction.
It has luminance signals for approximately 700 lines in the horizontal direction.

Therefore, in order to display the brightness signal completely, approximately 50
It is necessary to use a TF'TLCI with 0x700 pixels.

However, manufacturing such large-scale matrix arrays is difficult due to cost, yield, and manufacturing equipment.
It is desirable that the number of pixels be as small as possible. TFTLC used in Figure 2: D has 240 x 240 pixels, diagonal dimension is 2
Inches. Therefore, if this TFTLCDi is simply projected, it will merely display the loss of luminance information. In this embodiment, as shown in FIG. 8, 'I'l! ``A plurality of I'LCDs (two in this case) are used to improve resolution by forming images so that the pixels of the TFTI and CD are displaced by a fraction of a fraction.Figure 1 shows the displacement of the pixels. The pixels with diagonal lines are pixels of panel A, and the pixels with dots are pixels of panel B.The reason for displacing them in this way is to efficiently display horizontal and vertical brightness information on the screen. This is for the purpose of dispersion.

Further, as shown in FIG. 1(b), it is also possible to further increase the resolution by reducing the effective aperture ratio of the pixel. In Fig. 1(b), the shaded areas are effective pixels of panel A, the dotted areas are effective pixels of panel B, and the areas surrounded by broken lines and dashed-dotted lines follow the pitch of the matrix. It shows the pixel part.

The transparent electrode is made smaller to reduce the effective aperture ratio, and TPT
gate. An opaque wiring material was used for the base electrode, and the width of the electrode was expanded. Furthermore, it uses parallel Nicol and 90° TN (twisted nematic) modes that do not transmit light when no voltage is applied.

Next, driving of the TFTLCD will be briefly explained. The two TFTLCDs are alternately selected and driven with alternating current by the circuit shown in FIG. 4 according to the interlace method. Video signal input is made into inverted and non-inverted output,
This and the black display level VB of the panel are connected by a switch circuit (s
w1 to w6) to create a signal whose polarity is inverted every two fields (2F). This has been merged into the X driver.

FIG. 5 is a timing chart thereof. CLf is a shift register clock corresponding to one field (IF'), and Df is transmission data. 11 in Figure 4 is sW1-4
12 is an inversion buffer,
13 is a non-inverting buffer.

crwz is a clock synchronized with the horizontal synchronization signal, DxII
This is the data of the X driver. Same < CL v mDy
Hy driver clock and data. In this way, panel A shows odd fields (1atF in Fig. 5,
Panel B is selected as an even field (2ndF, 4th? in Figure 6).As a result, in the case of Example 1, one TFTL is selected.
It was possible to obtain approximately twice the resolution compared to a CD.

It was also possible to increase the efficiency of using light from the light source.

Embodiment 2 Embodiment 2 is a projection type display device in which a plurality of matrix liquid crystal panels (in the following description, two matrix liquid crystal panels) are imaged by one projection optical system.The liquid crystal panel is a TFTLCD similar to that of Embodiment 1.
was used. FIG. 6 shows the configuration of this embodiment.

The liquid crystal layer is a homogeneously aligned black guest-host liquid crystal, and the light shutter opens when an electric field is applied. 14 is a polarizing plate for improving optical shutter characteristics. 6 is a light source, 4 is a condenser lens, 9
is a projection lens. Panel A 15 and panel B 16 are arranged in close contact or close contact, and have the same liquid crystal orientation. Images of both panels are formed on the screen 8. For this reason, the transparent substrate of one panel is made of thin glass (in this case, polished glass with a thickness of 0.IU). The pixels of both panels are arranged with half a pixel displacement as shown in FIG. As in Example 1, the television signal follows the interlaced system and is divided into panels A and 2 for every 2 fields.
Panel B is displayed alternately.

As mentioned above, the liquid crystal is of a type in which the optical shutter opens when a voltage is applied, so it is necessary to apply voltage in order to open the optical shutter in unselected fields. Therefore, in driving, as in the first embodiment, odd fields are assigned to panel A, even fields are assigned to panel B, and so on. The level of the X driver input is selected by a switch circuit so that a field that is not selected takes a white level. The X driver input thus created is shown in FIG. The entire panel driving method can be performed in the same manner as shown in FIG.

In this way, it was possible to obtain approximately twice the resolution compared to the case where one TFTLCD was used.

Further, although a GH mode liquid crystal is used here, any transmission type electro-optic effect that does not use rotation of the plane of polarization can be applied.

Example 8 Example 8 is a full-color display device using eight display panels corresponding to the three primary colors R (red), G (green), and 9B (blue). R (red) panel 17tG (green) panel 18, B
(Blue) As shown in FIG. 9, the panel 19 splits the light beam, combines the light beams with a combining mirror 20 (for example, a semi-transmissive mirror or a dichroic mirror), and forms an image of the screen 8FC with the projection lens 9. 21 is a relay lens; is a condenser lens.

Here, the pixels of the R panel, G panel, and B panel are adjusted to be displaced regularly as shown in the circles in FIG. 8. In this figure, I made sure that there was no overlap between the art books,
As shown in FIG. 1(b), the aperture ratio of the pixels may be increased and the pixels may be overlapped. Figure 8 shows TFT as a display panel.
Although an LCD was used, it could be replaced with any display panel that forms an accurate matrix. R, G, B
It is difficult to obtain a distortion-free image with perfect convergence in a projection television that projects a CRT (cathode ray tube) that supports J3 primary colors onto a screen. According to the present invention, in which image formation is performed by matrix pixels,
You can adjust the position of the art book between different panels. As a result, the color shift between each color can be reduced, and the luminance information included in R and B can be effectively displayed, so that the resolution can actually be increased.

FIG. 9 shows the drive circuit used in this example. R.

The video signal separated into G and B is AC inverted for each field and input to the X driver.

CLZ, DZ, CI+y, and Dy are the X driver, the clock and shift data of the X driver. R
The same circuit is also provided for G and B.

This embodiment uses a transmissive TF as an IJ type display device.
Although a TLCD is used, it can also be implemented as a reflective light pulp structure in which light is modulated by entering it from the same direction as the direction in which the light source light is emitted. Display LCD mode is 90°T
Of course, you can also use other than N.

Of course, color display other than full color is also possible.

〔Effect of the invention〕

As described above, according to the present invention, high resolution can be obtained even in a matrix type display device composed of low-density pixels. Since low-density panels can be used as components, manufacturing is easy and the cost of the device can be reduced. Furthermore, in color display, the accurate addressing characteristics of the matrix display device make it possible to obtain a display with no color shift and high resolution.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of pixel displacement according to the present invention, in which (α) is a case where there is a pixel type, and (b) is a case where there is no pixel displacement. FIG. 2 is a block diagram of a general projection display device using an LCD. FIG. 8 is a diagram showing an example of the configuration of the composite projection system of the present invention. FIG. 4 is a diagram showing an example of a drive circuit when two TFTLCDs are used. FIG. 5 is a diagram showing signal waveforms at various parts of the circuit of FIG. 4. FIG. 6 is a diagram showing an example of the configuration when two TFTLCDs are used. FIG. 7 is a diagram showing the X driver input waveform in the case of FIG. 6. FIG. 8 is a block diagram of a full-color projection display device. FIG. 9 is a diagram showing an example of the drive circuit shown in FIG. 8. 1... Matrix LCD 2... Projection optical system 8... Screen 4... TFTLCD 9... Φ projection lens 15, 16, 17, 18, 19... TFTr,
, CD or more

Claims (4)

[Claims] (1) In a projection display device that obtains a display image by projecting an image formed by a matrix display device in which pixels are arranged in a matrix, the display image synthesized from the images of a plurality of matrix display devices is displaced. A projection display device characterized by: (2) The projection type display device according to claim 1, wherein the displacement of the displayed image is substantially one pixel or less. (3) The projection type display device according to claim 1, wherein the images of the matrix display device have the same geometric pitch. (4) The projection type display device according to claim 1, wherein the matrix display device displays an image corresponding to a display color.