JPH0494281A - Liquid crystal television receiver using photoconductive liquid crystal light bulb - Google Patents

Abstract

PURPOSE:To improve the yield by providing a voltage application means applying a voltage to two layers of a photoconductive layer and a liquid crystal layer to the television receiver and projecting a video signal converted into light onto a display element comprising a photoconductive liquid crystal light bulb. CONSTITUTION:A light source 11 converts a signal into a beam light, and it radiates to a photoconductive layer 1 of a liquid crystal light bulb via a polygon mirror 12 and a long size mirror 13. Thus, a contrast image with a resistance corresponding to a video image is formed onto the photoconductive layer 1 of the liquid crystal light bulb through the polygon mirror 12 and the long size mirror 13, a voltage is applied between transparent electrodes 3,3 in advance and a phase change takes place to a liquid crystal layer 2 corresponding to a part of the photoconductive layer 1 receiving the light. Then the video image is reproduced on the liquid crystal light bulb depending on the phase change. Thus, the yield is improved by the phase change.

Description

[Detailed description of the invention] (Al industrial application field This invention relates to improvements in liquid crystal televisions.

<b1 Prior Art In recent years, development of liquid crystal televisions using liquid crystals has been progressing in place of televisions using CRTs. The advantages of LCD televisions are that they can be made smaller, that is, the depth of the device can be made thinner, and power consumption can be reduced.

In order to switch the liquid crystal layer, an active matrix method using thin film transistors made of, for example, amorphous silicon is generally used.

(C1 Problems to be Solved by the Invention However, the active matrix method has the following problems.

Fabrication of thin film transistors requires microfabrication, and the number of steps is also large, requiring a large amount of expense for manufacturing equipment. Moreover, there is a drawback that the larger the number of steps, the lower the yield.

Furthermore, as the television becomes larger, the number of pixels must be increased accordingly, and a thin film transistor is required for each pixel, resulting in higher costs. Furthermore, in order to improve the resolution of the display, the thin film transistor must be made smaller, which is technically very difficult and increases the cost accordingly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a television using a photoconductive liquid crystal display that can improve the yield of the liquid crystal layer structure and reduce manufacturing costs.

(di Means for Solving the Problems) The present invention provides a display element consisting of a photoconductive liquid crystal light valve comprising a photoconductive layer, a liquid crystal layer, and voltage application means for applying a voltage to these two layers, and a projection means for converting the converted image into the image and projecting the converted image onto the display element.

Further, the projection means includes a light source that irradiates the video signal as beam light, a polygon mirror that operates the beam light in one direction, and a rotatable unit that operates the beam light in a direction perpendicular to the direction in which the beam light is operated by the polygon mirror. It may also be configured to include a long mirror.

(e) Function First, in the photoconductive layer of a photoconductive liquid crystal light valve,
When light corresponding to a video signal is irradiated by the projection means, the portion that is hit by the light becomes photoconductive and the resistance decreases.
Other parts remain very resistive. When a voltage is applied to the photoconductive layer and the liquid crystal layer by the voltage applying means in this state, most of the applied voltage is applied to the liquid crystal layer in the portion where the photoconductive layer has developed photoconductivity. On the other hand, in the areas where the photoconductive layer is not irradiated with light, the photoconductive layer has an insulating property, and the applied voltage is applied to the photoconductive layer and the liquid crystal layer. The voltage stamped on
A value that is high enough to cause the liquid crystal layer to switch when a voltage is applied only to the liquid crystal layer, and low enough that the liquid crystal layer does not cause switching when the voltage is distributed between the liquid crystal layer and the photoconductive layer. If set to , the liquid crystal layer will undergo switching due to the irradiation of light onto the photoconductive layer.

As a result, an image corresponding to a video signal from a television, video, etc. is written on the liquid crystal layer.

Further, when a polygon mirror and a rotatable elongated mirror are used as the projection means, the elongated mirror swings a beam of light in the main scanning direction to scan the display element in the main scanning direction. The polygon mirror swings the beam light in the sub-scanning direction, and the beam light is reflected by the elongated mirror and enters the display element. At this time, the beam light is scanned along the longitudinal direction of the long mirror. When receiving a television video signal and writing the video onto the liquid crystal layer, the reflection angle by the long mirror is changed by one pixel in the main scanning direction, and at one angle of the long mirror, the polygon mirror is used to change the reflection angle in the sub-scanning direction. The image is scanned by one scan. At this time, if the timing of the angle change of the elongated mirror and the m1 rotation speed of the polygon mirror are made to match the scanning speed of the television, the television image can be reproduced as is.

(fl Embodiment FIG. 1 is a diagram showing the cross-sectional structure of a liquid crystal light valve. A voltage is applied between the transparent electrodes 3.3 (voltage application means 4). Between the transparent electrodes 3.3, A photoconductive layer 1 and a liquid crystal layer 2 are disposed, and a reflective layer 5 is disposed between the photoconductive layer 1 and the liquid crystal layer 1.The reflective layer 5 absorbs light incident from the liquid crystal layer 2 side (see The light distribution processing films 6, 6 on both sides of the liquid crystal layer 2 are films that control the light distribution of the liquid crystal, and are provided as necessary. , a substrate glass with an antireflection layer on its surface on the side where the reference light is incident.

FIG. 2 shows the configuration of a device for writing information to the liquid crystal light valve, with FIG. 2(A) being a plan view and FIG. 2(B) being a side view.

For example, a television reception signal or a video signal is input manually to the light source 1). The light source 1) converts this signal into beam 1 and irradiates it from the photoconductive layer l side of the liquid crystal light valve 10 via the polygon mirror 1223 and the elongated mirror 13. The polycon mirror 12 is rotationally controlled as shown by the arrow in the figure (A), and swings the light from the light source in the sub-scanning direction. The range of light movement by the polygon mirror at this time is within the range of the long mirror 12 in the longitudinal direction. Further, as shown in FIG. 2B, the elongated mirror 12 is rotatably provided, and the reflection angle of light is variable. As the elongated mirror 12 rotates, the light emitted from the light source 1) is deflected in the main scanning direction.

In this way, a contrast image of resistance corresponding to an image is formed on the photoconductive layer of the liquid crystal light valve by the polygon mirror 12 and the elongated mirror 13. A voltage is applied in advance between the transparent electrodes 3, 3, and the photoconductive layer 1
The liquid crystal layer 2 corresponding to the portion irradiated with light undergoes a phase change. An image is reproduced on the liquid crystal light valve 10 according to this phase change state. At this time, for example, one of the 10 parts of the liquid crystal layer that is exposed to light and the 10 areas that are not exposed to light is in a transparent state, and the other is in a suspended state. Therefore, when the reference light 9 is irradiated onto the liquid crystal layer 2, the transparent portion of the reference light passes through the liquid crystal layer 2, is reflected by the reflective layer 5, and passes through the liquid crystal layer 2 again for reference. However, the suspended part cannot be detected by light. The presence or absence of this light can be seen as an image.

Further, one pixel at this time corresponds to the beam diameter of the light beam emitted from the light source, and if a color filter is arranged for each pixel, it can be referred to as a color image.

<Example 1> Phenylcyclohexane liquid crystal as a liquid crystal and cholesteric tunanoate as a chiral material in a weight ratio of 7 to 8%
The mixture was mixed to a film thickness of 7 to 8 μm. The film was made to have a welt pitch of 20% of this film thickness. As the light distribution film, a vertical light distribution film was used in which a silane treatment agent was applied to the surface of a reflective layer, which will be described later, and then subjected to high temperature treatment.

This liquid crystal is transparent when no voltage is applied, and becomes cloudy when a voltage is applied. In other words, in the areas where the light is not irradiated by the light source, the reference light passes through the liquid crystal layer and is reflected and seen as the reference light, but in the areas where the light is irradiated, the reference light is not reflected and the light is not recognized. . Therefore, in order to obtain the same image as the television signal, it is necessary to control the light source so that the pixel that receives the television signal is not irradiated with light, but the pixel that receives the television signal is irradiated with light.

The photoconductive layer is amorphous silicon (hereinafter referred to as a-5
It's called i. ) was used. Note that a-5i is made by, for example, a plasma CVD method with the substrate temperature set at 250 degrees.

In addition, a mixed gas of SiH and B2H6 is used as the raw material gas, and by appropriately setting the supply amounts of B and H, a
A-5i was prepared by using -5i as an intrinsic semiconductor and having dark conductivity of 2X10-'' and a photoconductive layer of 3X10-''.

Further, ITO was used as the transparent electrode, and a reflective material made of two types of materials with significantly different refractive indexes was used as the reflective layer. For example, Mg with a film thickness of about 0.1 to 0.5 μm
This is a dielectric mirror made of a multilayer film consisting of 10 to 15 laminated layers of a combination of F2 and ZnS and a combination of Si and SiO□. As mentioned above, a-5 is used as the photoconductive layer.
When i is used, it is desirable to use a combination of Sl and SiO□ to prevent contamination by atoms other than Si.

Further, an electric field of IKIlz, 5V is normally applied to the transparent electrode 3.3, but an alternating current electric field of IOV is applied before screen scanning is started in order to erase remaining image information.

With such a configuration, the light source 1) irradiates the liquid crystal light pulse 10 with a light beam via the polygon mirror 12 and the elongated mirror 13 in response to a television video signal. The liquid crystal layer in the area exposed to the light changes from transparent to milky white. This phase change of the liquid crystal is read out as an image using a reference light (Example 2) A twisted nematic material having positive dielectric anisotropy was used as the liquid crystal. This liquid crystal is made by orthogonally opposing glass that has been treated so that the liquid crystal molecules are uniaxially aligned parallel to the plane.
A liquid crystal is sealed inside. Liquid crystal molecules are oriented with a twist of 90 degrees, and when light is incident, it is propagated along the molecular axis and the plane of polarization is rotated by 90 degrees (having optical rotation). On the other hand, when a constant voltage is applied to the plate, switching occurs and the liquid crystal molecules change their alignment in the direction of the electric field, losing optical rotation and allowing light to pass straight through.

As shown in FIG. 3, polarizing plates 14a and 14b are arranged on the incident side and reflection side of the reference light with respect to the liquid crystal. This 2
The deflection plates 14a and 14b are 9 in the liquid crystal display when no voltage is applied.
Light that is twisted by 0 degrees is allowed to pass through, but light that passes straight through when a voltage is applied is blocked. In other words, this liquid crystal allows light to pass through when no voltage is applied, but when a voltage that causes switching is applied, light no longer passes through the liquid crystal. In FIG. 3, the configuration on the incident light side is the same as in the first embodiment.

A liquid crystal television device is constructed by laminating this liquid crystal, a photoconductive layer 1 reflective layer, and a transparent electrode. In this case, as in the first embodiment, a light source that emits light that is inverse to the television signal is used.

(gi Overall Effect of the Invention With γL, it is not necessary to provide a voltage application means such as TPT for each pixel as in the conventional actitus matrix, and the manufacturing cost can be reduced. The size can be reduced to the spot diameter of the light beam, and optical resolution can be expected.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the configuration of a liquid crystal light valve, and FIG. 2 is a diagram showing the configuration of a liquid crystal television according to the first embodiment. B) is a side view ″□
, FIG. 3 is a plan view showing the configuration of the reference light side of a liquid crystal television according to another embodiment. 1-photoconductive layer, 2-liquid crystal layer, 3-transparent electrode, 4-voltage application means, 5-reflective layer, 6-light distribution treatment, 7-substrate glass, 8-incident light, self-transparent light.

Claims (2)

[Claims] (1) A display element consisting of a photoconductive liquid crystal light valve, which includes a photoconductive layer, a liquid crystal layer, and a voltage application means for applying a voltage to these two layers, and converts a video signal into light and projects it onto the display element. A liquid crystal television using a photoconductive liquid crystal light valve, characterized in that a projection means is provided. (2) The projection means according to claim (1) includes at least a light source that irradiates the video signal as a beam light, a polygon mirror that scans the beam light in one direction, and a polygon mirror that scans the beam light in one direction. A liquid crystal television using a photoconductive liquid crystal light valve, comprising: a rotatable long mirror that scans in a vertical direction; and a photoconductive liquid crystal light valve.