CN2458641Y - Electric site selection liquid crystal light valve with medium mirror and nm-class composite film light barrier - Google Patents

Abstract

The utility model discloses an electrically addressable liquid crystal light valve with a dielectric reflector and a nanocomposite thin film light blocking layer, which sequentially comprises optical glass, a transparent conductive film, an orientation layer, a liquid crystal layer, an orientation layer, a dielectric reflector, Optical layer, control substrate. The dielectric mirror is SiO ₂ /TiO ₂ multilayer high reflection film or ZnS/MgF ₂ multilayer high reflection film. The utility model solves the influence of working under strong light on the control element, the film layer is firmly combined, and has a long service life. The light-blocking layer made of nano-composite film is beneficial to overcome the problem of dispersion at the edge of the pixel and partially improves the resolution. .

Description

Electrically addressable liquid crystal light valve with dielectric mirror and nanocomposite thin film light blocking layer

The utility model relates to a spatial light modulator, in particular to an electric site-selection reflective liquid crystal light valve with a medium reflection mirror and a nanocomposite film light-blocking layer.

The spatial light modulator related to the utility model mainly includes an optical addressing spatial light modulator using a photoconductive layer as a photosensitive material and working in a reflection mode; an active matrix addressing reflection mode spatial light modulator with TFT as a basic control unit Modulator. For the first type of light valve, Boswell et al. first applied for a patent (US. Pat. 4019807) on April 16, 1977. This light valve uses cadmium sulfide as the light guide layer, cadmium telluride as the light blocking layer and MgF ₂ / ZnS is a dielectric reflective layer. Then on January 24, 1989, Sterling applied for a patent (USPat.4799773) and proposed a new generation of reflective mirrors with a-Si:H as the photosensitive layer CdTe as the light-blocking layer and SiO ₂ /TiO ₂ as the multilayer dielectric mirror. Liquid crystal light valve, until January 22, 1992, Slobdin applied for a patent (USPat.5084777), and proposed to use a-SiGe: H as the light blocking layer of the light valve, which solved the problem of light blocking layer and a-Si: H light guide layer combination problem. In 1993, we directly applied for the patent of reflective liquid crystal light valve using transition-modified amorphous silicon as the photosensitive layer (China Pat: ZL93108193.9) and the patent of reflective liquid crystal light valve with crystalline film as light blocking layer ( China Pat: ZL93116734.5), which further improves the performance of the optical address reflective liquid crystal light valve. Generally speaking, this type of light valve has been developed relatively maturely. For the second type of light valve, its reflection mode is mostly used in weak light conditions, and it is reported that materials such as aluminum with high reflection are directly plated on the back electrode for reflection.

Considering that in large-screen projection devices, the first type of optical addressing light valve is easy to prepare, but because its imaging modulation is written by other optical signals, the system is bulky and consumes energy, and the final signal is taken from the light guide The signal transmitted from the first layer is limited by the structure of the light valve and the current transmission mode, so it is difficult to further improve the contrast; in the face of the second type of light valve that can be directly addressed by the circuit, although the system is small in size, it is easy to write signals. Direct control, and due to the improvement of TFT preparation technology in recent years, the performance has been further improved, but because of this type of light valve, especially for light valves driven by active matrix (such as TFT-LCD), the TFT itself is more sensitive to light , The performance is seriously affected by light, especially under the strong light irradiation when projecting on a large screen, this effect is even greater, so it is necessary to conduct more research on this type of light valve.

The purpose of the utility model is to provide a reflective liquid crystal light valve for large-screen projection with electric address selection.

In order to achieve the above object, the utility model takes the following measures:

Electric site-selection reflective liquid crystal light valve for large-screen projection, which sequentially includes optical glass, transparent conductive film, alignment layer, liquid crystal layer, alignment layer, control substrate, and a dielectric mirror is arranged between the alignment layer and the control substrate and light blocking layer.

Another electrically addressable liquid crystal light valve with a dielectric mirror and a light-blocking layer of a nanocomposite film, which sequentially includes optical glass, a transparent strip electrode, an alignment layer, a liquid crystal layer, an alignment layer, a transparent strip electrode, a substrate, and A dielectric mirror is arranged between the alignment layer and the transparent strip electrode.

Compared with the prior art, the utility model has remarkable effects:

1) The light-blocking layer of the composite nano-grain film has high light absorption efficiency and completely absorbs part of the light passing through the dielectric mirror (although the transmitted part is even less than 0.1%, if it is used for large-screen projection, the light intensity is as high as hundreds of thousands Lx, this part of the light will not be ignored), which solves the influence of working under strong light on the control components.

2) Due to the existence of a large number of crystal grains comparable to the film thickness scale in this film, the high absorption rate and conductivity can be controlled, while the lateral direction is more insulator, which overcomes the problem caused by the excessive driving signal in the film thickness direction. The efficiency is reduced by generating more voltage drops, and it prevents the resolution from being reduced due to lateral charge diffusion in some structures.

3) Considering that if the liquid crystal light valve is covered with a passivation layer (such as silicon nitride) on the TFT surface, and the light blocking layer itself is a thin film composed of Si, N, C, etc., the light valve design uses The lattice structure of the light-blocking layer matches well with silicon nitride, etc., the film layer is firmly bonded, and the durability is good.

4) Considering the lattice structure of the light-blocking layer material made of Si, N, C and other composite films, SiO ₂ /TiO ₂ hard film multi-layer dielectric mirror reflection layer can be used at this time. The two are well matched and the bonding force is good. Strong and long service life.

Describe in detail below in conjunction with accompanying drawing.

Fig. 1 is a schematic diagram of the structure of an electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite thin film light blocking layer for active matrix large-screen projection.

Fig. 2 is a schematic structural diagram of an electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite film light-blocking layer for passive matrix large-screen projection.

An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite film light-blocking layer, which sequentially includes an optical glass 9, a transparent conductive film 8, an alignment layer 7, a liquid crystal layer 6, an alignment layer 5, and control substrates 1 and 2 A dielectric mirror 4 is provided between the alignment layer 5 and the control substrates 1 and 2 .

Another electric addressing liquid crystal light valve with a dielectric mirror and a nanocomposite film light-blocking layer, which sequentially includes an optical glass 20, a transparent strip-shaped electrode 19, an alignment layer 18, a liquid crystal layer 17, an alignment layer 16, a transparent strip-shaped A dielectric mirror 15 is arranged between the electrode 13 , the substrate 12 , the alignment layer 16 and the transparent strip electrode 13 .

A composite nanocrystalline silicon light-blocking layer or a CdTe light-blocking layer 3 is provided between the above-mentioned dielectric mirror and the control substrates 1 and 2 . A composite nanocrystalline silicon light-blocking layer or a CdTe light-blocking layer 14 is provided between the dielectric mirror 15 and the transparent strip electrode 13 . The dielectric mirror is SiO ₂ /TiO ₂ multilayer high reflection film, or ZnS/MgF ₂ multilayer high reflection film. The dielectric mirror is SiO ₂ /TiO ₂ multilayer high reflection film, or ZnS/MgF ₂ multilayer high reflection film. The composite nanocrystalline silicon light-blocking layer is made of amorphous silicon or SiCx or SiNx as a matrix material, and light-sensitive silicon or germanium as a nanocrystalline grain material. The optical energy gap of the compound crystal silicon light-blocking film is less than 1.6eV, the crystal content is 10-40%, the grain size is 40-500nm, and the visible light absorption coefficient is ^10-4-10-5 cm ^-1 . The film thickness of the compound crystal silicon light-blocking layer is equivalent to the crystal grain size in the film.

The working principle of the utility model is:

The image signal of light valve is provided by matrix control (the control circuit is the same as prior art), and after an image signal is provided by the matrix, it is equivalent to applying a voltage corresponding to the image signal on both sides of the liquid crystal layer, that is, each image The voltage on the pixel point corresponds to the strength of the image signal under certain conditions, which is equivalent to applying a latent image represented by a voltage on both sides of the liquid crystal layer. Under a certain orientation condition (the orientation layer is 5 and 7 Or 16 and 18), the liquid crystal layer can have such a property that the voltage applied to the liquid crystal layer is different, and the polarization direction of the polarized light passing through the liquid crystal layer changes accordingly. At this time, the incident light passes through the liquid crystal layer that retains the voltage latent image, and after being reflected by the medium reflection layer 4 or 15, the polarization angle of each point of the reflected light obtained will also be different due to the different voltages of each point on the liquid crystal layer 6 or 17. Different, that is, at this time, the reflected light actually retains a latent image corresponding to the signal provided by the matrix control signal represented by the different polarization angles of the reflected light at each point, and let this reflected light pass through an appropriate polarization analysis system , a corresponding image represented by different light intensities at each point can be obtained.

In this liquid crystal light valve, the optical isolation between the incident strong light and the control matrix mainly depends on the reflective layer 4, which can generally reach more than 99.9%. If 0.1% transmission is considered, the transmitted light intensity can reach hundreds of Lx, which is enough to affect the TFT device that is sensitive to light and reduce the image quality. Therefore, in order to ensure the normal operation of the light valve, at this time A composite nanocrystalline silicon thin film light blocking layer or CdTe light blocking layer can be used to absorb the leaked light.

In the composite nanocrystalline silicon film light-blocking layer of this liquid crystal light valve, due to controlling the existence of a large number of complex phase grains, and by controlling the appropriate doping in the grains, and controlling the grain size to be equivalent to the film thickness, Therefore, in the normal direction of the film, it shows crystal characteristics with high light absorption efficiency; while in the lateral direction of the film, due to the existence of a large number of grain boundaries and non-conductive dielectric phases, it shows high resistance characteristics. Therefore, this light-blocking layer has high light absorption efficiency, and is less likely to cause a decrease in resolution and TFT control characteristics even when in contact with TFTs. At the same time, considering the bonding fastness between the light-blocking layer and the adjacent film layer, the composite nanocrystalline silicon thin film formed with Si, N, C, etc. as the substrate material is controlled and selected, which solves the problem of structural matching with the adjacent film layer.

Claims (9)

1. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite film light blocking layer, which sequentially includes optical glass [9], transparent conductive film [8], alignment layer [7], and liquid crystal layer [6] , alignment layer [5], control substrate [1], [2], characterized in that a dielectric mirror [4] is set between said alignment layer [5] and control substrate [1], [2]. 2. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite film light-blocking layer according to claim 1, characterized in that the dielectric mirror and the control substrate [1], [2] There is a composite nanocrystalline silicon light-blocking layer or a CdTe light-blocking layer [3]. 3. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite film light blocking layer, which sequentially includes optical glass [20], transparent strip electrodes [19], alignment layer [18], and liquid crystal layer [17] ], alignment layer [16], transparent strip electrode [13], substrate [12], it is characterized in that being provided with dielectric mirror [15] between said alignment layer [16] and transparent strip electrode [13] ]. 4. A reflective liquid crystal light valve for electric address selection for large-screen projection according to claim 3, characterized in that a composite nanometer Crystalline silicon light blocking layer or CdTe light blocking layer [14]. 5. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite film light-blocking layer according to claim 1 or 2, characterized in that said dielectric mirror is SiO ₂ /TiO ₂ multilayer high Reflective film, or ZnS/MgF ₂ multilayer high reflective film. 6. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite film light-blocking layer according to claim 3 or 4, characterized in that said dielectric mirror is SiO ₂ /TiO ₂ multilayer high Reflective film, or ZnS/MgF ₂ multilayer high reflective film. 7. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite thin film light blocking layer according to claim 2 or 4, characterized in that said composite nanocrystalline silicon light blocking layer is a non- Crystalline silicon or SiCx or SiNx is used as a matrix material, and light-sensitive silicon or germanium is used as a composite material for nanocrystalline grains. 8. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite thin film light-blocking layer according to claim 2 or 4, characterized in that the optical energy gap of the composite crystal silicon light-blocking layer film is less than 1.6 eV, the crystal content is 10-40%, the grain size ^{is 40-500nm, and the visible light absorption coefficient is 10-4-10-5 cm -1} . 9. An electrically addressable liquid crystal light valve with a dielectric mirror and a nanocomposite thin film light blocking layer according to claim 2 or 4, characterized in that the film thickness of the composite crystal silicon light blocking layer is the same as the thickness of the light blocking layer in the film The grain size is comparable.

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