JPH10153798A - Active matrix liquid crystal panel, and projection system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a numerical aperture and to prevent display unevenness and light leakage by using a conductive light-shieldable film having apertures to expose a pixel electrode on the substrate surface of an array substrate having thin-film transistors (TFTs). SOLUTION: Metallic thin film 12 consisting of chromium(Cr) as the light- shieldable films selectively formed into a prescribed shapes in formed on the glass substrate 11 as the first substrate. Polycrystalline silicon films 14 as semiconductor layers consisting of ohmic regions 14a and channel regions 14b via first interlayer insulating films 13 consisting of silicon oxide (SiO2 ) are formed above the respective metallic thin films 12. In such a case, the metallic thin film 12, which is a light-shieldable film, has the apertures to expose the pixel electrode and completely shut off the direct light made incident perpendicularly on the array substrate surface from the array substrate side and, therefore, the light does not advance to the semiconductor regions of the TFT parts any more. The increase of the leak currents of the TRs by the light is thus prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an active matrix liquid crystal panel having a thin film transistor for a projection type display device and a projection system using the same.

[0002]

2. Description of the Related Art In recent years, an active matrix type liquid crystal display device (AM-LC) having a thin film transistor (TFT) for each pixel electrode of a liquid crystal panel.
D) is being actively studied because higher image quality can be obtained compared to a simple matrix type display device.

In general, a conventional active matrix type liquid crystal display device has a liquid crystal panel section schematically shown in FIG. That is, in FIG. 11, a first substrate 101 made of transparent glass or the like and a second substrate 102 made of transparent glass or the like are disposed to face each other, and a liquid crystal formed in a matrix is provided on the first substrate 101. The driving pixel electrode 103 and the same row (=
A scanning line 104 for applying a voltage to each pixel electrode 103 belonging to the same column (= row), a data line 105 for applying an image signal voltage to each pixel electrode 103 belonging to the same column (= row), A thin film transistor portion 106 including a source electrode 106s connected to the line 105, a gate electrode 106g connected to the scanning line 104, and a drain electrode 106d connected to the pixel electrode 103 is formed. Therefore, the first substrate 101
Is called an array substrate 101, while a second substrate 102
A transparent conductive film 107 to be a counter electrode of the pixel electrode 103 on the array substrate 101 is formed, and is called a counter substrate 102.

[0004] In general, a transmissive liquid crystal display device needs to transmit light from a back light source.
Reference numeral 03 denotes a transparent conductive film, and a color filter is formed on each pixel of the counter substrate 102 when color display is performed on the liquid crystal panel portion.

In the liquid crystal panel configured as described above, when the voltage applied to the liquid crystal layer is changed according to the image signal during the period when the thin film transistor 106 is driven, the light from the back light source passing through the liquid crystal panel is transmitted. Since the transmittance changes, the change in the light transmittance is displayed as an image. Note that the semiconductor material of the thin film transistor portion 106 is amorphous silicon (a-Si), polycrystalline silicon (p-Si) with high mobility, or cadmium selenium (CdS
e) and the like are used.

FIG. 12 is a configuration diagram of a typical three-panel projection display device (liquid crystal projector) using the above-mentioned conventional liquid crystal display panel as a light valve for light switching. Using a dichroic mirror (DM) and a reflecting mirror (M), light using a metal halide lamp or the like as a light source is divided into light paths for each of the three primary colors, and red (R), green (G), or blue ( The light is projected onto a light valve (LB) composed of a liquid crystal panel for each color of B), and each color is switched by each light valve (LB) to project an image on a screen. Usually, a TN (twisted nematic) liquid crystal has been used as a display mode of the liquid crystal in the liquid crystal panel.

However, since a light valve made of TN liquid crystal cuts about half of the incident light by the polarizing plate on the incident side, it is difficult to effectively use the light emitted from the lamp. Therefore, in recent years, in order to make effective use of light from a light source, liquid crystals are dispersed in a polymer as a liquid crystal material, and light transmission and dispersion at an interface between the polymer and the liquid crystal are controlled by an applied voltage to switch light. Liquid crystal light valves using polymer dispersed liquid crystals have been announced (Aisa Display '95 S16-3p
343) According to this display method, since it is not necessary to use a polarizing plate, it is possible to secure twice or more the output of light for the same input with respect to the display method using TN liquid crystal.

As one of the important performance factors required for a light valve for obtaining a brighter and higher-contrast liquid crystal projector, an aperture ratio (a portion contributing to actual light modulation with respect to the size of one pixel). Ratio) is required to be high. In addition, a portion that does not contribute to light modulation in one pixel includes a thin film transistor portion in the pixel,
These are a scanning line portion, a data line portion, an auxiliary capacitance portion parallel to the liquid crystal, and a gap portion between the pixel electrode and each bus line.

[0009]

In a liquid crystal display device having the above-mentioned thin film transistor, when light is irradiated to a portion which does not contribute to the modulation of light, for example, when light is incident on a channel of the thin film transistor portion, FIG. The drain current (Id) -gate voltage (Vg) of the transistor shown in FIG.
Since the current in the OFF state increases as shown by the characteristic curve of (1), there is a problem that the switching characteristics deteriorate. In particular, when the above-described polymer-dispersed liquid crystal is used as a liquid crystal material for the liquid crystal panel, a malfunction of the transistor occurs due to light scattering. Generally, single-crystal silicon or polycrystalline silicon having high mobility is used as a material of a thin film transistor. When the thin film transistor has a coplanar structure in which the semiconductor layer exists on the glass substrate side with respect to the gate electrode, the channel region of the thin film transistor is formed directly below the gate electrode in a self-aligned manner, so that the light incident direction is the gate direction. Since it is necessary to use the electrode as its light-shielding body, it is necessary to make light incident from the counter substrate side. If the liquid crystal material to be used is a TN liquid crystal, light passing through the panel basically travels straight, so this is sufficient. However, when a polymer dispersion type is used as the liquid crystal material, scattering of light inside the liquid crystal panel is reduced. The light generated and scattered at the angles shown in the figure penetrates below the gate electrode, increases the off-state current of the transistor, and degrades the contrast.

In a light valve using a TN liquid crystal, a black matrix is formed on the opposite substrate side.
The contrast is improved by preventing light from being incident on the channel portion of the thin film transistor portion, and by covering a region where the liquid crystal is not modulated by the voltage to prevent light from passing through this region. However, since the size of the assembly accuracy of the black matrix is independent of the size of one pixel, as the size of the pixel decreases, the ratio of the area of the black matrix portion to the pixel increases, and the aperture ratio decreases. For light valves used in liquid crystal projectors, there is a strong demand for miniaturization of the system. Therefore, smaller liquid crystal light valves are also desired. This is a very restrictive factor.
The relationship between the panel size and the aperture ratio of the conventional general liquid crystal light valve shown in FIG. 14 (assuming the assembly accuracy is 3 μm and the number of pixels is 640 × 480. The alignment accuracy of the array substrate is 2
When looking at μm, the minimum line width (Lmin) and the minimum space between the same layers (Smin) are 5 μm), the upper limit of the aperture ratio for a panel size of about 1.5 inches is 55%.

Therefore, in recent years, in order to obtain a higher aperture ratio for the problem of miniaturization, the black matrix (B
BM-on-array technology (Display Manufacturing Technology Confere) for transferring the M) layer from the counter substrate side to the array substrate side
nce, Santa Clara, 1995, pp 107), and a photosensitive black resin material is used for the black matrix on the matrix array. However, in the active matrix liquid crystal panel for a projection display device using the conventional BM on-array technology, when a black resin is used as a material of a black matrix, the film thickness is 1 μm or more due to a limit of a light shielding ratio of the resin material. This necessitates a non-light distribution area of the liquid crystal in the vicinity of the step portion of the edge of the black matrix, so that there is a problem that display characteristics such as light leakage deteriorate. Furthermore, when this liquid crystal panel is used in a projection display device, the thermal conductivity of the black resin is low, so that the temperature inside the panel increases due to light irradiation,
There is a problem in that display unevenness is caused by fluctuation of transmittance due to temperature unevenness inside the panel.

A first object of the present invention is to increase the aperture ratio, eliminate display unevenness and light leakage due to high heat and high illuminance peculiar to a projection display device, and provide a thin film transistor with light resistance. The purpose is to be able to. A second object of the present invention is to realize a projection system having excellent light resistance when a polymer dispersed liquid crystal is used as a liquid crystal material.

[0013]

SUMMARY OF THE INVENTION A first object of the present invention is as follows.
This is achieved by using a conductive light-shielding film having an opening for exposing a pixel electrode on a substrate surface of an array substrate having a thin film transistor. Specifically, the first and second substrates opposing each other and sandwiching the liquid crystal layer,
A plurality of scanning lines formed on the first substrate and extending in parallel with each other; a plurality of data lines formed on the first substrate and extending in parallel with each other and intersecting the plurality of scanning lines; A matrix-shaped pixel electrode formed in each region surrounded by the scanning lines and the data lines on the first substrate; and formed at each intersection of the scanning lines and the data lines on the first substrate. A gate electrode connected to the scanning line, a source electrode connected to the data line, and a drain electrode connected to the pixel electrode, and the data line and the pixel electrode And a light-shielding film formed between the first substrate and the thin-film transistor, the light-shielding film exposing each of the pixel electrodes to transmitted light. Open Parts it is an Configurations that have.

According to the first aspect of the present invention, since the light-shielding film has the peripheral covering portion covering only the peripheral portion of the pixel electrode, the aperture ratio can be increased, and the thin film transistor can be formed from the first substrate side having the thin film transistor. Light incident on the constituent semiconductor layer can be blocked.

The light-shielding film may be made of a metal. Since the thermal conductivity is larger than black resin,
Along with suppressing the temperature rise of the light valve,
The film thickness can be made smaller than that of the black resin, and a non-aligned region of liquid crystal due to a step formed around the light-shielding film is less likely to be generated. As a result, a liquid crystal light valve having higher display characteristics can be provided. Further, the light-shielding film made of the metal can be connected to a power supply, and a peripheral covering portion of the light-shielding film that covers a peripheral portion of the pixel electrode can be a storage capacitor. Further, by inverting the polarity of the voltage level applied to the data line and the polarity of the voltage level applied to the light-shielding film, the amplitude of the image signal voltage can be suppressed, so that power consumption can be reduced. .

In order to prevent light from entering from above the thin film transistor, it is preferable that the source electrode covers the channel above the thin film transistor.
When the liquid crystal material sealed between the first and second substrates is a composite of liquid crystal and a polymer (polymer dispersed liquid crystal), light scattered in the liquid crystal layer enters from the upper surface of the thin film transistor. Particularly, light scattered at a shallow angle enters the inside of the channel, and the above-described OFF current increases, thereby deteriorating the image quality. This can be prevented.

By using the active matrix liquid crystal panel of the present invention, the direction of incidence of light from the light source can be directed to the substrate side on which the thin film transistor is formed. It is possible to provide a projection system that prevents incidence and has high contrast.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the configuration of an array substrate of an active matrix liquid crystal panel for a projection display according to a first embodiment of the present invention. As shown in FIG. 1, chromium (C) as a light shielding film selectively formed in a predetermined shape is formed on a glass substrate 11 as a first substrate.
r) and a first interlayer insulating film 1 made of silicon oxide (SiO ₂ ) above each metal thin film 12.
3, the ohmic region 14a and the channel region 14
A polycrystalline silicon film 14 is formed as a semiconductor layer made of b. A gate electrode 16 is selectively formed on each polycrystalline silicon film 14 on a channel region 14b via a gate insulating film 15, and a contact is formed on a second interlayer insulating film 17 for insulating the gate electrode 16. A source electrode 19 and a drain electrode 20 are respectively formed in the respective ohmic regions 14a through holes, and a pixel electrode 22 made of ITO (indium tin oxide film) electrically connected to one end of the drain electrode is connected to the third interlayer. It is formed on the insulating film 21 so as to extend to the side end of the source electrode 19 of the adjacent thin film transistor portion.

Hereinafter, a method of manufacturing an active matrix liquid crystal panel for a projection display according to a first embodiment of the present invention will be described with reference to the drawings. 2 and 3 are cross-sectional views in the order of steps showing a method for manufacturing a liquid crystal panel according to the first embodiment of the present invention.

A substrate for forming a thin film transistor, that is, only an array substrate will be described. First, as shown in FIG. 2A, a metal thin film made of chromium (Cr) serving as a light shielding film is formed on a transparent glass substrate 11. After 12 is deposited to a thickness of 100 nm, it is patterned into a predetermined shape. The material of the metal thin film 12 is, in addition to chromium, a metal such as titanium (Ti), tantalum (Ta), aluminum (Al), an aluminum alloy, nickel (Ni), or tungsten (W) having a sufficient light-shielding performance, or Black non-metallic thin film that can withstand the switching element forming process of the process, for example, an organic material such as a black resist, or silicon monoxide (Si
O) or other inorganic materials.

Next, as shown in FIG. 2B, a first interlayer insulating film 13 made of silicon oxide (SiO ₂ ) is formed on the entire surface of the glass substrate 11 as an insulating film of the metal thin film 12 so as to have a thickness of 100 nm to 1 μm. Deposited to a thickness of Other materials for the interlayer insulating film may be tantalum oxide (Ta ₂ O ₅ ), silicon nitride (SiN), or a composite layer thereof. After that, the plasma CV is formed on the first interlayer insulating film 13.
A semiconductor layer 14A made of amorphous silicon (a-Si) serving as a seed crystal is deposited by the method D. Amorphous silicon (a-Si) serving as a seed crystal may be formed by a low-pressure CVD method or a sputtering method. After that, the semiconductor layer 14A is melted and crystallized using an excimer laser to form a polycrystalline silicon (p-Si) film 14B. Note that an argon (Ar) laser can be used instead of the excimer laser. In addition, solid-phase growth of polycrystalline silicon may be used for forming polycrystalline silicon.

Next, as shown in FIG. 2C, silicon oxide (SiO ₂ ) is formed on the entire surface of the glass substrate 11.
After depositing a gate insulating film 15 having a thickness of 100 nm, a gate electrode forming film is deposited on the gate insulating film 15 to form a gate electrode 16 in a desired pattern. Phosphorus (P) or boron (B) is ion-implanted into the silicon film 14B through the gate insulating film 15 to form an ohmic region 14a. The region into which the impurity is not implanted becomes the channel region 14b of the thin film transistor.

Next, as shown in FIG. 3A, the gate electrode 16 and the source
After depositing a _second interlayer insulating film 17 made of silicon oxide (SiO ₂ ) to insulate the drain electrode to a thickness of 400 nm, the second interlayer insulating film 17 and the gate insulating film 15 are formed in the same pattern. Etching is performed to form respective contact holes 18 for the source electrode and the drain electrode.

Next, as shown in FIG. 3B, a source electrode 19 and a drain electrode 20 are formed of a metal such as aluminum (Al).

Next, as shown in FIG. 3C, a third interlayer insulating film 21 made of silicon oxide (SiO ₂ ) insulating the source electrode 19 and the drain electrode 20 over the entire surface of the glass substrate 11. Is deposited to a thickness of 100 nm,
After selectively forming the contact portion 22a between the drain electrode 20 and the pixel electrode on the third interlayer insulating film 21, the pixel electrode 22 made of ITO is formed to extend to the side end of the source electrode 19 of the adjacent thin film transistor. Thus, an array substrate having an active matrix array is completed. FIG. 4 shows a plan view after the completion of the array.

As described above, according to the present embodiment, the metal thin film 12, which is a light-shielding film, completely shields the direct light 33 which is perpendicularly incident on the array substrate surface from the array substrate 31 side. Light does not enter the semiconductor region, whereby leakage current of the transistor due to light does not increase, so that favorable display characteristics can be obtained.

Although the above-mentioned effects are produced irrespective of the material of the light-shielding film, in this embodiment, since the light-shielding film is formed of metal, the thermal conductivity is higher than that of the black resin. Since the temperature rise of the light valve can be suppressed and the film thickness can be made smaller than that of the black resin, the non-aligned region of the liquid crystal due to the step formed in the periphery of the light-shielding film is less likely to be generated. A liquid crystal light valve having high display characteristics can be provided.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. The difference from the first embodiment is that the aperture ratio is further improved by using the peripheral covering portion 68b between the pixel electrode and the light-shielding film shown in FIG. 4 as the storage capacitor of the pixel.

Specifically, the light-shielding film 68 of the array substrate shown in FIG. 4 is replaced with a scanning line 62, a data line 63, a polycrystalline silicon film 64, a drain electrode 67, and a pixel electrode 61.
Peripheral covering portion 68b formed by covering the peripheral portion of
And an opening 68 a for exposing the pixel electrode 61, and is formed of a metal such as chrome electrically connected to the drain electrode 67. Further, a take-out portion of the light-shielding film 68 is formed outside the display area, and the potential of the light-shielding film 68 is controlled to function as a storage capacitor.

The operation of each electrode of the liquid crystal panel configured as described above will be described below with reference to the timing chart shown in FIG. FIG. 5 is a timing chart of a voltage applied to each electrode of the liquid crystal panel according to the second embodiment of the present invention. In FIG. 5, Vg (n) and Vg (n +
1) are the nth and (n + 1) th drive potentials of the scanning line, respectively. Vs is the waveform of the data line to which the image signal is added, and Vs (c) is the center value of the image signal. Vs
(H) and Vs (l) indicate the high level and the low level of the image signal, respectively.

Vt (c), Vt (h), and Vt (l) are the signals of the center level, high level, and low level of the voltage applied to the counter electrode, respectively. The polarity of the signal between the level and the low level is inverted. Thus, the amplitude of the image signal voltage can be reduced.

Ve (c), Ve (h) and Ve (l) are the central level, high level and low level signals of the voltage applied to the common electrode, respectively, and are connected to the light-shielding film 68 having conductivity. It is assumed that In this case, it is possible to reduce the signal level by setting Ve = Vt, and it is also possible to control Vt and Ve independently. Further, the image signal, the counter voltage and the voltage of the common electrode
The polarity may be changed every horizontal scanning period. As a result, the amplitude of the image signal applied to the data line can be reduced to half or less as compared with the case where the polarity is not inverted.

As described above, according to the present embodiment, the light-shielding film has a function as a light-shielding film, and the peripheral covering portion between the pixel electrode and the light-shielding film shown in FIG. Therefore, a storage capacitor line for generating a storage capacitor is not required. Therefore, the aperture ratio of the area occupied by the storage capacitor line can be further increased.

(Third Embodiment) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. The active matrix liquid crystal panel for a projection type display device of the present embodiment is constituted by the same array substrate as that of the first embodiment or the second embodiment described in FIG.

As a feature of this embodiment, as shown in FIG. 6, when the source electrode 19 and the drain electrode 20 are formed in a predetermined pattern after the formation of the contact hole, the pattern of the source electrode 19 for transmitting an image signal is changed to the channel of the TFT. The structure covers the portion and prevents light from entering from above. By adopting this structure, it is possible to reliably block light entering the liquid crystal panel from above,
Therefore, good display characteristics can be obtained without increasing the leakage current of the transistor due to light. Since the process diagrams are substantially the same as those in FIGS. 2 and 3, the same members are denoted by the same reference numerals and description thereof will be omitted.

(Fourth Embodiment) Hereinafter, a fourth embodiment of the present invention will be described. As a feature of this embodiment, a polymer dispersed liquid crystal in which liquid crystal is dispersed as fine droplets in a polymer is used instead of a TN liquid crystal in a liquid crystal material sealed in a light valve. Type liquid crystal
The light switching operation is performed in the scattering state shown in FIG. 8A and the transmission state shown in FIG.

In the scattering state shown in (a), since the polymer-dispersed liquid crystal is in a state where no voltage is applied to the array substrate 31 and the counter substrate 32, the orientation of the liquid crystal in the droplet 41 existing in the polymer is changed. Is arbitrary, and light is reflected in an arbitrary direction at the interface between the liquid crystal and the polymer in the droplet 41.

The light whose incident angle in the liquid crystal cell as shown in FIG. 3 of the first embodiment is smaller than a right angle with respect to the substrate surface is a light-shielding film or wiring in the case of a general TN liquid crystal. Other than the reflection by the edge portion of the pattern, it is relatively unlikely to occur.

However, in the case of the polymer-dispersed liquid crystal, since the amount of scattered light having such a small incident angle increases, the ratio of the scattered light traveling from the upper surface of the array substrate to the TFT side also increases significantly. .

Therefore, as shown in FIG. 9, a comparison between the case where the polymer dispersed liquid crystal 51 is used as the liquid crystal material and the case where the TN liquid crystal 52 is used is shown by the voltage-transmittance characteristic curve.
The amount of change between the voltage when irradiating the light shown by the solid line and the voltage when not irradiating the light shown by the dashed line from the back of the FT is larger when the TN liquid crystal 52 is used than when the polymer dispersed liquid crystal 51 is used. Greater than.

Therefore, in the TFT structure of the third embodiment, the effect becomes more remarkable when the polymer dispersed liquid crystal is used as the liquid crystal material of the light valve.

FIG. 10 shows the configuration of a projection system using the liquid crystal light valve of the fourth embodiment. In this case, the direction of incidence of light from the lamp is on the TFT substrate side. The reason for this is that the configuration of the fourth embodiment basically has a structure that prevents light from entering the channel regardless of the direction of incidence of light. However, in the light-shielding film below the TFT and the source electrode covering the upper part of the channel, In terms of the shielding effect, the lower light-shielding film is more effective in terms of area, and the intensity of the incident light from the lamp is lower than the diffused light or reflected light in the liquid crystal light valve with respect to the incident light from the lamp. Because it is big.

As apparent from the above description, the active matrix liquid crystal panel for a projection display according to the present invention includes a light-shielding film formed between a thin film transistor and a first substrate having the thin film transistor. Since the light-shielding film has an opening for exposing the pixel electrode, the aperture ratio can be increased, and the strong light from the back light source incident on the semiconductor layer forming the thin film transistor on the first substrate can be obtained. Since incident light can be blocked, light does not enter the semiconductor layer of the thin film transistor from the first substrate side, and thus leakage current of the transistor due to light does not increase. Therefore, favorable display characteristics can be obtained. it can.

Further, according to the active matrix liquid crystal panel for a projection display device according to the present invention, since the light-shielding film is made of metal, the heat conductivity is larger than that of the black resin, so that the temperature rise of the light valve can be suppressed. And the thickness can be made smaller than that of the black resin, so that a non-aligned region of the liquid crystal due to a step formed in the periphery of the light-shielding film is less likely to occur, and as a result, deterioration of display characteristics can be suppressed. it can.

Further, according to the active matrix liquid crystal panel for a projection display device according to the present invention, since the light-shielding film is electrically connected to the power supply, the peripheral covering portion covering the peripheral portion of the pixel electrode in the light-shielding film. Becomes a storage capacitor, so that a storage capacitor line for generating the storage capacitor is not required, thereby making it possible to further increase the aperture ratio of the area occupied by the storage capacitor line.

Further, by inverting the polarity of the voltage level applied to the data line and the polarity of the voltage level applied to the light-shielding film, the amplitude of the image signal voltage can be suppressed, thereby reducing power consumption. be able to.

Further, since the source electrode covers the upper part of the channel of the TFT, it is possible to prevent light from entering from above the TFT.

According to the active matrix liquid crystal panel of the present invention, the liquid crystal material sealed between the first and second substrates is a polymer dispersed liquid crystal which is a composite of liquid crystal and polymer. Even if the amount of scattered light having a small incident angle increases, the drain current does not increase when the applied voltage is turned off, so that display unevenness can be reliably suppressed.

Further, by configuring a liquid crystal projection system using the active matrix liquid crystal panel of the present invention, the light incident direction is set to the TFT substrate side,
It is possible to provide a projection system having a very high shielding effect on photoconductive properties.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view of an array substrate of an active matrix liquid crystal panel for a projection type display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view in a process order showing a method for manufacturing an active matrix liquid crystal panel for a projection display according to a first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a method of manufacturing an active matrix liquid crystal panel for a projection display according to a first embodiment of the present invention in the order of steps.

FIG. 4 is a configuration plan view of an array substrate of an active matrix liquid crystal panel for a projection display according to the first embodiment of the present invention.

FIG. 5 is a timing chart of a voltage applied to each electrode of a liquid crystal panel according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of an array substrate of an active matrix liquid crystal panel for a projection display according to a third embodiment of the present invention.

FIG. 7 is a configuration plan view of an array substrate of an active matrix liquid crystal panel for a projection display according to a third embodiment of the present invention.

FIG. 8 is a schematic diagram illustrating a light switching operation by transmitting and scattering light of a polymer dispersed liquid crystal in an active matrix liquid crystal panel for a projection display according to a fourth embodiment of the present invention.

FIG. 9 is a graph showing a voltage-transmittance characteristic curve of a polymer-dispersed liquid crystal and a TN liquid crystal.

FIG. 10 is a configuration diagram of a liquid crystal projector using an active matrix liquid crystal panel according to a fifth embodiment of the present invention.

FIG. 11 is a perspective view schematically showing a liquid crystal panel of a conventional active matrix type liquid crystal display device.

FIG. 12 is a configuration diagram of a typical three-panel projection display device (liquid crystal projector) using a conventional liquid crystal display panel as a light valve for light switching.

FIG. 13 is a graph showing a characteristic curve of drain current (Id) -gate voltage (Vg) of a transistor.

FIG. 14 is a graph showing the relationship between the panel size and the aperture ratio of a conventional general liquid crystal light valve.

[Explanation of symbols]

 Reference Signs List 11 glass substrate 12 metal thin film 13 first interlayer insulating film 14 polycrystalline silicon film 14a ohmic region 14b channel region 14A semiconductor layer 14B polycrystalline silicon film 15 gate insulating film 16 gate electrode 17 second interlayer insulating film 18 contact hole 19 Source electrode 20 Drain electrode 21 Third interlayer insulating film 22 Pixel electrode 22a Contact part 31 Array substrate 32 Counter substrate 33 Direct light 34 Reflected light 41 Droplet 51 Polymer dispersed liquid crystal 52 TN liquid crystal 61 Pixel electrode 62 Scanning line 63 Data Line 64 polycrystalline silicon film 65 source electrode 66 gate electrode 67 drain electrode 68 light-shielding film 68a opening 68b peripheral covering

Continuing on the front page (72) Inventor Kazuo Inoue 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Tetsuya Kawamura 1006 Kadoma Kadoma, Kadoma City Osaka Pref.

Claims (7)

[Claims] A first and a second substrate facing each other and sandwiching a liquid crystal layer; a plurality of scanning lines formed on the first substrate and extending in parallel with each other; A plurality of data lines formed on the first substrate and extending in parallel with each other and intersecting the plurality of scanning lines; and a matrix formed in each region on the first substrate surrounded by the scanning lines and the data lines. A pixel electrode formed at each intersection of the scanning line and the data line on the first substrate and connected to the scanning line; a source electrode connected to the data line; A thin film transistor having a drain electrode connected to the pixel electrode, the thin film transistor including a semiconductor layer for controlling conduction between the data line and the pixel electrode by the potential of the scanning line, and between the first substrate and the thin film transistor Formed An active matrix liquid crystal panel, comprising: a light-shielding film, wherein the light-shielding film has an opening for exposing each of the pixel electrodes to transmitted light. 2. The active matrix liquid crystal panel according to claim 1, wherein said light-shielding film is made of metal. 3. The active matrix liquid crystal panel according to claim 2, wherein said light shielding film is electrically connected to a power supply. 4. A voltage level applied to the data line,
4. The active matrix liquid crystal panel according to claim 3, wherein the driving is performed by inverting the polarity of the voltage level applied to the light-shielding film to each other. 5. A first and second substrate facing each other and sandwiching a liquid crystal layer; a plurality of scanning lines formed on the first substrate and extending in parallel with each other; A plurality of data lines formed on the first substrate and extending in parallel with each other and intersecting the plurality of scanning lines; and a matrix formed in each region on the first substrate surrounded by the scanning lines and the data lines. A pixel electrode formed at each intersection of the scanning line and the data line on the first substrate and connected to the scanning line; a source electrode connected to the data line; A drain electrode connected to the pixel electrode; and a thin film transistor including a semiconductor layer that controls conduction between the data line and the pixel electrode by a potential of the scanning line. Light incident from above the thin film transistor To Active matrix liquid crystal panel Guyo the source electrode is equal to or covering the channel upper portion of the thin film transistor 6. The liquid crystal device according to claim 1, wherein a material of the liquid crystal layer sandwiched and sealed between the first and second substrates is a composite of liquid crystal and a polymer. An active matrix liquid crystal panel according to the item. 7. A projection system wherein an incident direction of light from a light source is from a substrate side on which the thin film transistor is formed, and the active matrix liquid crystal panel according to claim 6 is used as a light valve.