JPH01280726A - lcd light bulb - 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] [Industrial application field] The present invention relates to a liquid crystal light valve.

[Conventional technology]

The conventional optical writing type liquid crystal light valve is disclosed in Japanese Patent Application Laid-Open No. 59-2
As shown in No. 16128, the photoconductive layer was directly irradiated with laser light, and the impedance change of the photoconductive layer was used to drive the liquid crystal.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, the photoconductive layer is directly irradiated with laser light, so if amorphous silicon, which can easily be made into a large area and has low manufacturing costs, is used for the photoconductive layer,
The wavelength sensitivity of amorphous silicon ranges from 0.5 μm to 0.6 μm.
It has a peak at a wavelength of μm and hardly responds to near-infrared light. Therefore, it is not possible to use small semiconductor lasers that are currently available at a practical level and are cheap; instead, gas lasers such as He-N e, which are large, expensive, and require a separate modulation mechanism, are used. For example, when an image drawing device such as a projection display is manufactured using an optical writing type liquid crystal light valve, there is a limit to how much the system can be made smaller and less expensive.

Therefore, the present invention solves these problems,
The purpose is to provide a liquid crystal light valve that can form images using a semiconductor laser that emits light in the near-infrared region even if amorphous silicon is used for the photoconductive layer.

[Failure to solve the problem]

The liquid crystal light valve of the present invention includes: (1) a liquid crystal layer between a first transparent electrode substrate in which a photoconductive layer and a light separation mirror layer are sequentially laminated, and a second transparent electrode substrate facing the light separation mirror side; (2) The wavelength conversion layer has an excited level composed of at least one type of rare earth ion. (3) The wavelength conversion layer is excited to an excited level or by light having a wavelength outside the wavelength sensitivity band of the photoconductive layer, (4) The wavelength conversion layer is of at least one type. (5) At least one emission spectrum of the photoluminescence wavelength emitted by the wavelength conversion layer is within the wavelength sensitivity band of the photoconductive layer. It is characterized by

〔Example〕

FIG. 1 shows an embodiment of the liquid crystal light valve of the present invention.

1 and 1' are ITO (Indium Tin 0x
3 is an amorphous silicon photoconductive layer formed by a glow discharge method, and 4 is a light separating mirror made of a dielectric multilayer film. , is formed by forming a multilayer film of silicon and silicon oxide on the photoconductive layer by electron beam evaporation method, 5 and 5'' are spacers, and the liquid crystal 6 is sealed in the space created by the cono spacers 5 and 5'. .7 is a wavelength conversion layer formed on a transparent substrate 1, and in this example, it was obtained by dispersing microcrystals of Yb-Er (Y, OC]) in a resin and coating and baking them. 8 is a power supply connected to the transparent electrodes 2 and 2, 9 is a laser beam emitted from a near-infrared semiconductor for optical recording on the liquid crystal layer 6, and 10 is a readout beam emitted from a xenon lamp light source, etc. As shown in Fig. 2, when a part of the wavelength conversion layer is irradiated with laser light 9, the light irradiated part of the wavelength conversion layer is excited and emits the fluorescence shown in 11. Fluorescent light 11 reaches the photoconductive layer 3 through the transparent substrate 1 and the transparent electrode 2, and brings about an impedance change in three regions corresponding to the light irradiated portions of the photoconductive layer 3.This impedance change of the photoconductive layer causes the connection from the outside to be made. The partial pressure ratio of the voltage applied by the power supply 8 to each layer changes, and a voltage higher than the voltage Vih required to drive the liquid crystal is applied to the area corresponding to the light irradiation part of the liquid crystal layer, and the liquid crystal in this area is not exposed to light. The stable state is different from that when the laser beam 9 is not irradiated, and optical writing is performed using the laser beam 9. Originally, amorphous silicon has a thickness of 0.55 μm to 0.5 μm.
It has a wavelength sensitivity peak around 60 μm, and hardly responds to near-infrared to infrared light of 0.75 μm or more. However, Ys OCI 7 doped with Yb-Er shown in this example is photoexcited by near-infrared light and emits fluorescence having a wavelength of visible light. Among the fluorescence, the fluorescence of 0.54 .mu.m and 0.66 .mu.m in particular matches well with the wavelength sensitivity range of amorphous silicon described above, so that the photoconductive effect can be efficiently produced. Therefore, even if a semiconductor laser that emits near-infrared light is used, it is possible to generate an impedance change in the photoconductive layer sufficient to drive a liquid crystal. We were able to create an optical writing type liquid crystal light valve using a laser as the writing light source.

In this example, the wavelength conversion layer was formed by dispersing fine powder of Yb-Er-topped Y, OCI, in a resin, coating and firing, but other materials such as glass, CaW, etc.
Oi, L a F s, G d F s, BaY
Fs, BaLuFs, YOCllYs QCl 7
, I-a G a Oi as the parent body, P r '”
, N d” ”, S m ” ”, D y' ”
, HO''', Er3+, Tm3+, Yb3+ rare earth ions may be doped, similarly dispersed in resin, coated and fired.Also, impurity-added NdC1
, , and rare earth chlorides such as Pr C1s can also be used.

FIG. 3 shows a projection display using the liquid crystal light valve of the present invention. 21 is a near-infrared semiconductor laser, 22
is the light beam 2 emitted from the near-infrared semiconductor laser 21
3 is a rotating polygon mirror that scans and deflects linearly, 23 is an imaging lens, and 24 is a reflecting mirror that reflects the light beam 23 at a certain angle, and is supported on a movable table 25. 2
6 is a ball screw for driving the movable table 25;
Connected to a stepping motor via gears 27 and 28, the movable table reciprocates on a straight line and scans the light beam 23 in a two-dimensional plane.

25 is the liquid crystal light valve shown in FIG. 1, and image formation is performed according to the above-described principle. The image formed on the liquid crystal light valve is created by irradiating readout light 27 emitted from a xenon lamp light source 26 onto the liquid crystal light valve 25 via a polarizing beam splitter 28, projecting the reflected light, and enlarging it with a zoom lens 29. The image is then projected onto the screen 30 to form an image. As described above, the liquid crystal light valve of the present invention enables image formation even when using a semiconductor laser that emits near-infrared light, thereby realizing miniaturization and cost reduction of the system.

〔Effect of the invention〕

As shown in 2 below, according to the present invention, amorphous silicon is suitable as a photoelectric conversion material because it is relatively easy to increase the area, is low cost, has high light absorption efficiency, and has a quantum efficiency close to 1. It has become possible to provide an optical writing type liquid crystal light valve that can form images with high efficiency using a semiconductor laser that is small, lightweight, and low-cost, and that can be used for example in projection displays. When used for such purposes, it has become possible to make the system smaller and lower in price. In addition, conventionally, when using amorphous silicon, a gas laser or the like was used and a separate modulation mechanism had to be prepared, but the present invention makes it possible to use a semiconductor laser, so a special modulation mechanism is required. is no longer necessary, leading to a reduction in the number of parts and improving the system's ability to be used in parallel applications.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the liquid crystal light valve of the present invention. FIG. 2 is a diagram showing a driving principle related to an embodiment of the present invention. FIG. 3 is a diagram showing a projection type display using the liquid crystal light valve of the present invention. 1.1'...Transparent substrate 2.2'...Transparent electrode 3...Photoconductive layer 4...Light separating mirror 5.5'...Spacer 6...Liquid crystal layer 7... Fluorescent light emitting layer 8...Power supply 9...Laser light 10...Reading light or more

Claims (5)

[Claims] (1) A liquid crystal layer is provided between a first transparent electrode substrate in which a photoconductive layer and a light separation mirror layer are sequentially laminated, and a second transparent electrode substrate facing the light separation mirror side; A liquid crystal light valve characterized by having a wavelength conversion layer formed on a transparent electrode substrate. (2) The liquid crystal light valve according to claim 1, wherein the wavelength conversion layer has an excited level composed of at least one type of rare earth ion. (3) The liquid crystal light valve according to claim 1, wherein the wavelength conversion layer is excited to an excited level by light having a wavelength outside the wavelength sensitivity band of the photoconductive layer. (4) The liquid crystal light valve according to claim 1, wherein the wavelength conversion layer has an emission level composed of at least one type of rare earth ion. (5) The liquid crystal light valve according to claim 1, wherein at least one emission spectrum of the photoluminescence wavelength emitted by the wavelength conversion layer is within the wavelength sensitivity band of the photoconductive layer.