JPH04289837A - Projection type display device - Google Patents

Abstract

PURPOSE:To miniaturize a device, facilitate adjustment and further to improve light utilizing efficiency by using a space light modulator of matrix electrode address system for writing in a space light modulator of light address system, and arranging both the modulators adjacently placed. CONSTITUTION:Write-in light 12 is modulated by a space light modulator 13 of matrix electrode address system to generate flux of light having picture information with quantity of light two-dimensionally changed. A picture on the space light modulator 13 is guided onto a space light modulator 16 of light address system with space frequency characteristic not so deteriorated by an optical image transmitting means 15. Since the space light modulator 16 modulates read light 17 in accordance with quantity of the write-in light, the picture on the space light modulator 16 is displayed enlarged when modulated flux of light is projected by a lens.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of Industrial Application The present invention relates to a projection type display device for displaying an enlarged image of a spatial light modulator on a screen.

0002

2. Description of the Related Art Among projection display devices for enlarging and projecting images from a spatial light modulator using liquid crystal, two systems have been put into practical use. One is a method that uses a spatial light modulator with a matrix electrode addressing method. In this method, light source light is directly input to the spatial light modulator with a matrix electrode addressing method, and the modulated light is extracted by transmission or reflection and is displayed by projection. It is something to do. The other method uses an optically addressed spatial light modulator, for example, SID DIGE.
As reported on pages 327-328 of ST 90, CRT (cathode-ray tube
) is used to write data into an optical addressing spatial light modulator. In this system, an optically addressed spatial light modulator works as an optical amplifier that converts a relatively weak image on a CRT into a high-power image.

0003

However, each of the prior art techniques has many problems. In the former method using a spatial light modulator using a matrix electrode addressing method, an active matrix method is generally used in which a switching transistor is provided for each pixel. Since the temperature rises and the display quality deteriorates, only relatively low-output display is possible.

- Since the characteristics of the switching transistor easily change due to the influence of ambient temperature, cooling is required to stabilize the characteristics.

[0005] Generally, pixel electrodes cannot be formed in the wiring portion of the matrix electrode or the switching transistor portion, so that the utilization efficiency of light from the light source is low.

[0006] There is a problem.

In addition, in the latter method using a spatial light modulator of the optical addressing method, the CRT used for writing requires high resolution, so the depth is about 6 times the raster size, and the depth is about 6 times the raster size. If this method is used, the device becomes very large.

- Electron beam adjustment such as CRT convergence adjustment is troublesome.

- When the installation location of the device is changed, the traveling direction of the electron beam changes due to the influence of the earth's magnetism, making it necessary to readjust the convergence.

- Since writing is performed on the spatial light modulator in response to the light emission of the phosphor on the CRT, it is driven by duty, resulting in low light utilization efficiency.

There is a problem as follows.

SUMMARY OF THE INVENTION The present invention aims to solve these problems, and its purpose is to provide a projection type display device that is small in size, easy to adjust, has high light utilization efficiency, and has a high output. .

[0013]

[Means for Solving the Problems] The projection type display device of the present invention uses an optical addressing type spatial light modulator in the light source light modulation section, and this spatial light modulator has a matrix arranged extremely close to it. It is characterized in that writing is performed using a light beam modulated by an electrode addressing type spatial light modulator. Further, a thin optical image transmitting means is disposed between the optical addressing type spatial light modulator and the matrix electrode addressing type spatial light modulator.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The projection type display device of the present invention will be explained in detail below.

FIG. 1 is a diagram showing the structural concept of a light source light modulation section of a projection type display device according to the present invention. Writing light source 11
The writing light 12 from the matrix electrode addressing type spatial light modulator 13 (hereinafter also referred to as m-SLM 13)
The light flux is modulated by , resulting in a light beam having image information with a two-dimensional change in light amount. The image on the m-SLM 13 is transferred to an optical addressing type spatial light modulator 16 (hereinafter referred to as p
- SLM16). Note that even without this optical image transmission means 15, the m-SLM 13 and p-SL
By placing M16 very close to each other, it is possible to transmit an optical image with less deterioration. The p-SLM 16 modulates the read light 17 according to the amount of writing light, so if the modulated light beam is projected by a lens, the p-SLM
The image above 16 is enlarged and displayed. The spatial light modulator 13 using the matrix electrode addressing method used here has a liquid crystal layer as a light modulation layer, and is generally referred to as a simple matrix method, in which a voltage is directly applied to the liquid crystal layer by duty driving using row electrodes and column electrodes. There are two methods: a method called an active matrix method, in which a switching transistor is formed in each pixel and the write voltage is maintained for a certain period of time.

FIG. 2 is a schematic cross-sectional view showing an example of the configuration of the optically addressed spatial light modulator 16 shown in FIG. 1. As shown in FIG. The writing light 12 is applied to a photoconductive layer 23 (e.g. CdS film, a-S
i:H film, BSO film), and its impedance changes depending on the amount of light. An AC voltage of about 1 kHz is applied between transparent electrodes 22 (for example, ITO film, ZnO film) formed on two glass substrates 21, and the voltage is distributed according to the thickness and dielectric constant of each layer. Ru. Therefore,
When the impedance of the photoconductive layer 23 decreases, its distributed voltage decreases, and the decreased voltage is applied to the other layers. Further, the light modulation layer 26 is a liquid crystal layer or a liquid crystal-polymer composite layer, and the alignment state of liquid crystal molecules changes depending on the applied voltage. Therefore, the voltage applied to the light modulation layer 26 in the portion irradiated with light is higher than the voltage applied to the light modulation layer 26 in the portion not irradiated, so the arrangement state of the liquid crystal molecules changes, and the arrangement state changes. The readout light 17 is modulated according to. Since a reflective mirror 25 made of a dielectric multilayer film is formed next to the liquid crystal layer 26, the readout light 17 is modulated and reflected at the same time, and the modulated light 28
is extracted as. The light shielding layer 24 in this figure is for preventing the impedance of the photoconductive layer 23 from decreasing due to the readout light 17 slightly leaking from the reflecting mirror 25 made of a dielectric multilayer film.

Next, four methods will be described as specific examples of the optical image transmitting means 15 in FIG.

The first method is a method in which an optical image is directly guided by an optical fiber plate having a structure in which optical fibers having a fiber diameter smaller than the pixel size are bundled, and an example of this method is shown in FIG. The almost parallel writing light 12 is m-S
It is modulated by the LM 13 and becomes a light beam containing image information. Then, this light beam enters the optical fiber plate 32, and while repeating total reflection inside each optical fiber, directly p-
is transmitted to a photoconductive layer within SLM 16. At this time, if the diameter of each optical fiber is equal to or larger than the pixel size, the spatial frequency characteristics of the image will deteriorate considerably, so to prevent this, it is necessary to make the diameter of each optical fiber smaller than the pixel size. Also, in this case, by omitting the glass substrate on the optical fiber plate 32 side of the p-SLM 16 and stacking the transparent electrode directly on the optical fiber plate 32,
Deterioration of the spatial frequency characteristics of the image can be reduced.

The second method is a method in which each optical fiber is made into a rectangular cross section in the first method, and its vertical and horizontal widths are made to almost match the pixel pitch. An example of this method is shown in FIG. The active matrix type liquid crystal panel 45 has a counter substrate 4
1, an address substrate 42, and a liquid crystal layer 4 sandwiched between them.
It consists of 4. In the active matrix type liquid crystal panel 45, pixels cannot be formed on the switching transistors, gate lines, and source lines.
Since the incident light is modulated and transmitted only through a portion of the area for one pixel where the transparent electrode is formed, the displayed image becomes an area-discrete image. In this case, if the individual optical fibers in the optical fiber plate 43, which is an optical image transmitting means, are transmitted in correspondence with each pixel, while the optical fibers are transmitted by repeating total reflection,
The light flux becomes a uniform light flux within the optical fiber. Therefore, when writing is performed on the p-SLM 16 using this method, even if the aperture ratio of the active matrix type liquid crystal panel 45 is small, the writing spreads to approximately the size of the pixel pitch while passing through the optical fiber plate 43. The use efficiency of the readout light 17 is increased.

The third method is to image each pixel of the m-SLM onto the photoconductive layer of the p-SLM using a microlens array, and an example of this method is shown in FIG. 5. The light flux that has passed through the pixel electrodes of the active matrix liquid crystal panel 45 enters the microlenses on the microlens array 53 that correspond one-to-one with each pixel electrode, and p-
An image of the light flux at the pixel electrode is formed on the photoconductive layer 23 in the SLM 16 . If the pixel size is made almost equal to the pixel pitch of the active matrix liquid crystal panel 45 by enlarging the image, even if the aperture ratio of the active matrix liquid crystal panel 45 is low, the p-S
In the LM 16, the use efficiency of the readout light 17 can be increased.

The fourth method is to form an image on the m-SLM onto the photoconductive layer of the p-SLM using a focusing optical fiber lens array, and an example of this method is shown in FIG. When an image signal is input to the simple matrix liquid crystal panel 61, the writing light 12 is modulated and passes through the focusing optical fiber lens array 62 to the p-SLM 1.
imaged onto the photoconductive layer in 6. In this case, even if the parallelism of the incident light was poor, the image on the liquid crystal panel could be formed with almost no deterioration in its spatial frequency characteristics, and the second and third methods required alignment. However, in this case it is unnecessary. FIG. 7 is a perspective view showing an example of the configuration of the optical system of the projection display device of the present invention. The writing light source 11 is
In this figure, three thin devices (for example, thin film type or organic dispersion type electroluminescent elements, thin fluorescent lamps, etc.) are used. It is also possible to use one divided into three equal parts. The light beam from this writing light source 11 is modulated by the m-SLM 13 to contain image information, and passes through the optical image transmission means 15 to the p-SLM.
Address LM16. The light source device 74 is composed of a point light source lamp (for example, a xenon lamp, a metal halide lamp, or a halogen lamp) and a reflecting mirror, and emits substantially parallel light or condensed light. The prism 73 is composed of two triangular prisms, and utilizes the angular dependence of light reflectance on the surface of the glass material to completely reflect the light beam from the light source device 74, and modulate the light reflected from the p-SLM 16. Light is allowed to pass through. The light source light reflected by this prism 73 is then passed through a color light separation/synthesizer 72 (in this figure, a cube prism including a red light reflecting dichroic mirror and a blue light reflecting dichroic mirror in a cross shape) converts the light into three primary colors. Each primary color light is modulated by the corresponding p-SLM 16, enters the color light separation/synthesizer 72 again, and is combined. Thereafter, the modulated light flux that has passed through the prism 73 is enlarged and projected by a projection lens 75, and an image is formed on a screen 76. In this figure, the p-SLM 16, the color light separation/combiner 72, and the prism 73 are arranged at a small distance, but
When using a layer (liquid crystal-polymer composite layer) that controls incident light by scattering and transmitting it as the light modulation layer of p-SLM16, it is possible to reduce the light reflected from the surface of the glass material by adhering them with optical glue. The display contrast ratio can be increased.

[0022]

As described above, in the projection display device of the present invention, a matrix electrode addressing spatial light modulator is used as a writing means for an optical addressing spatial light modulator, and both are placed close to each other. By arranging the apparatus, the apparatus becomes compact, and since alignment adjustment only needs to be performed first, it is easy to carry, and moreover, it is possible to realize high output with high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration concept of a light source light modulation section of a projection display device according to the present invention.

FIG. 2 is a schematic cross-sectional view showing a configuration example of an optically addressed spatial light modulator used in the projection display device of the present invention.

FIG. 3 is a diagram showing a configuration when an optical fiber plate with a small fiber diameter is used as the optical image transmission means used in the projection display device of the present invention.

FIG. 4 is a diagram illustrating a configuration in which an optical fiber plate in which the size of the fiber cross section is approximately equal to the pixel pitch is used as the optical image transmission means used in the projection type display device of the present invention.

FIG. 5 is a diagram showing a configuration when a microlens array is used as the optical image transmission means used in the projection display device of the present invention.

FIG. 6 is a diagram showing a configuration in which a focusing optical fiber lens array is used as the optical image transmission means used in the projection display device of the present invention.

FIG. 7 is a perspective view showing an example of the configuration of the optical system of the projection display device of the present invention.

[Explanation of symbols]

11...Writing light source 12...Writing light 13...Matrix electrode addressing type spatial light modulator 15...Optical image transmission means 16...Optical addressing type spatial light modulator 23...Light Conductive layer 25...Reflector 26 made of dielectric multilayer film...Light modulation layer 32...Optical fiber plate 45...Active matrix liquid crystal panel 5
3... Microlens array 61... Simple matrix liquid crystal panel 62...
- Focusing optical fiber lens array 72... Color light separation/combiner 73... Prism 74... Light source device 75... Projection lens 76... Screen

Claims (2)

[Claims] 1. A projection type display device that modulates light source light with a spatial light modulator to enlarge and display an image input to the spatial light modulator, wherein the spatial light modulator is an optically addressed spatial light modulator. 1. A projection type display device characterized in that writing is performed on the spatial light modulator using a light beam modulated by a matrix electrode addressing type spatial light modulator disposed extremely close to each other. 2. The projection display device according to claim 1, wherein a thin optical image transmission means is disposed between the optical addressing type spatial light modulator and the matrix electrode addressing type spatial light modulator. A projection display device characterized by: