JP2000214444A - Liquid crystal display device and projection type liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a projection type liquid crystal display device which is miniaturized, accurate and easily usable by utilizing a scattered type liquid crystal element.

SOLUTION: Light from a light source 11 is reflected by a reflection mirror 12 through a condensing lens 13. Reflected light is converted into parallel beams by a condensing lens 16, and made incident on the scattered type liquid crystal element 15 provided in three directions by a dichroic mirror 14, colored in three colors, red, green and blue by the liquid crystal element, made to pass through the mirror 14, the lens 16 and an enlarging lens 17 again and projected to a screen. Then, a photodetector 1704 is provided at the focus position of the lens 16, and a function for adjusting the light source based on the detected result by the photodetector 1704 is added. By using the scattered type liquid crystal element, the utilization rate of the light is made twice as high as the conventional one so as to obtain a reflection type optical system, thereby, the miniaturization is realized and the exchange of a lamp is facilitated by the photodetector.

COPYRIGHT: (C)2000,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection type display device for displaying an image on a liquid crystal element and projecting the image on a screen. The present invention relates to a small, high-precision, easy-to-use liquid crystal display device and a liquid crystal projection display device using the same.

[0002]

2. Description of the Related Art An international symposium digest of S.I.D. is a liquid crystal projection type display that uses three TN (Twisted Nematic) type liquid crystal elements as an image source and projects a color image on a screen. (1986) pp. 375-378 (International Symposium Digest of SID pp 375-378)
(1986)).

Recently, instead of a TN type liquid crystal, a polymer dispersed type liquid crystal which disperses a liquid crystal in a transparent resin and changes the state of scattering and transparency according to the strength of an externally applied electric field has been developed. The apparatus used is described in International Symposium Digest of SID (1990), pages 227 to 230 (Internati).
onal Symposium Digest of SID, pp. 227-230 (1990)). In this paper, a thin film transistor is manufactured using a polysilicon thin film.

Further, a projection type liquid crystal display device is disclosed in
There is -12291 publication. In this known example, the light source is arranged at a position shifted from the central axis, and the projection lens is moved with respect to the central axis.
It is provided at a position symmetrical to the light source.

[0005]

Among the above-mentioned prior arts, those driven by a thin film transistor and using a TN liquid crystal do not allow light to pass through the thin film transistor itself or the wiring electrode portion of a row or a column. The effective area of the pixel electrode is small, and the effective area is usually 10% to 3%.
It must be about 0%. Further, because of the light absorbing property of the polarizing plate, which is indispensable for the TN-type liquid crystal, the light is reduced to 1/2 by the polarizing plate.
It will be below. Therefore, the transmittance of the liquid crystal element is significantly reduced, so that in order to increase the brightness on the screen, a light source that consumes a large amount of power has to be used.

Further, even in the case of using polymer dispersed liquid crystal, light loss due to the polarizing plate can be eliminated, but the area occupied by the thin film transistor and the wiring electrode portion is still large, and the transmittance of the liquid crystal element is still insufficient. .

Further, in the conventional projection type liquid crystal display device, since the light source and the projection lens are disposed at positions symmetrical with respect to the central axis, not only the size cannot be sufficiently reduced, but also the lamp which is the light source fails. Could not be exchanged by an amateur and sent the goods to the manufacturer for exchange. This is because if the optical axis shifts by several microns due to the light source, the resolution is extremely deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small-sized liquid crystal projection type display device in which the loss of light in the display device is reduced, the light use efficiency is increased, and the power consumption is small.

It is another object of the present invention to provide a small and highly reliable device in which a driving circuit for a liquid crystal element is built in the liquid crystal element.

Another object of the present invention is to provide an apparatus having a built-in optical axis adjustment function that allows easy lamp replacement.

[0011]

In order to achieve the above object, the present invention provides a reflection type liquid crystal device which employs a light scattering type liquid crystal instead of a TN type liquid crystal and further has a reflection layer provided inside the liquid crystal device. The optical system is also a reflection type projection optical system.

In order to achieve the other object, not only a pixel driving active element such as a transistor but also a peripheral driving circuit are incorporated in the element, so that a liquid crystal element is constituted by using a silicon single crystal substrate. It is. By arranging the light source at a position of about 90 degrees with respect to the projection axis, the lamp as the light source can be easily replaced, and the optical meter can be downsized.

Further, a photodetector for adjusting the optical axis and a lamp position driving circuit are incorporated.

[0014]

When a light scattering type liquid crystal is used instead of a TN type liquid crystal, there is no need to use a polarizing plate, so there is no essential light absorption, and the loss of light generated by the light source can be reduced.
A bright display can be obtained with a low-power light source.

Further, by using a reflection type liquid crystal element,
Since a reflective layer (shared with a pixel electrode) can be provided also on an active element such as a transistor or a wiring electrode, the effective area available for display can be increased.
A brighter display can be obtained.

Further, by making the projection optical system a reflection type, the color separation optical system and the color synthesizing optical system can be shared by the same optical system, and the light source is located at a position 90 degrees with respect to the projection axis. By doing so, it is easy to reduce the size of the device.

Further, in the reflection type liquid crystal element, since one substrate does not need to be transparent, a silicon single crystal substrate can be used as the substrate. For this reason, a transistor with higher performance than a thin film transistor can be obtained, and a peripheral circuit can be built in, so that the number of connections to the outside can be significantly reduced, and a decrease in reliability such as poor connection is prevented.
The device can be further miniaturized.

Further, by providing the photodetector and the lamp position driving mechanism, the user can easily change the lamp when replacing the lamp, and the fine adjustment is performed by the apparatus.

[0019]

FIG. 1 shows an embodiment of the present invention.

FIG. 1 shows an optical system of a liquid crystal projection display, in which a white light generated from a light source 11 is focused on a reflecting mirror 12 and a white light reflected on the reflecting mirror 12 is reflected by a lens 13.
Reflection type liquid crystal elements 15-R, 15-G, and 15-B corresponding to the three primary colors are converted into parallel lights through the color separation / synthesis optical system 14.
16 and the reflective liquid crystal element 15-R,
It comprises a lens 17 for reflecting light reflected from 15-G and 15-B and passing through the color separation / synthesis optical system 14 and the lens 16 again on the screen. Each of the three reflective liquid crystal elements has image signals Vs (R) and Vs obtained by decomposing the color image signal Vs into three primary color components by the drive circuit 18.
Driven by s (G) and Vs (B).

Here, as the light source 11, a metal halide lamp with a reflecting mirror was used, and a dichroic reflecting mirror for reflecting only visible light so as to prevent infrared rays unnecessary for display from being incident on the liquid crystal element was used.

The lens 13 has a role of focusing on the reflecting mirror 12, and the distance between the principal point of the lens and the condensing portion of the reflecting mirror 12 is arranged so as to substantially match the focal length. . The light-collecting portion of the reflecting mirror 12 includes lenses 16 and 1
7, the light condensing part after being reflected by the liquid crystal elements 15-R, 15-G, 15-B is shifted from the reflecting mirror 12, and There is no loss of light reflected by the reflector.

The lens 16 is located at a position substantially apart from the focal point of the reflecting mirror 12 by a focal length, and converts incident light into substantially parallel light to be incident on the next color separation / synthesis optical system 14. The color separation / synthesis optical system 14 is composed of a dichroic prism, and reflects or transmits the red component of the incident white light to the right, the green component downward, and the blue component to the left.

The liquid crystal elements 15-R, 15-G, and 15-B are reflection type liquid crystal elements using light-scattering liquid crystal, and are driven by color-separated image signals corresponding to each color. When the transparent portion is bright on the screen, the light scattering portion is displayed dark on the screen in the device.

The reflection type liquid crystal elements 15-R, 15-G, 15
2, the gate of the transistor 31 is connected to the row electrode 47 and the drain is connected to the column electrode 46 as shown in FIG.
And the source is connected to the pixel electrode. In FIG. 2, a storage capacitor 52 is provided in parallel with a capacitor formed of the liquid crystal 50 and a transparent electrode 51 common to each pixel. The other end of the storage capacitor 52 maintains the storage capacitors of all pixels at the same potential by a dedicated extraction electrode 53.

The storage capacitor 52 is provided for the purpose of preventing the drive voltage of the liquid crystal from being lowered by its own leak current, and is not required when the impedance of the liquid crystal is sufficiently high.

FIG. 3 is a sectional view of the liquid crystal element. The light scattering type liquid crystal 61 is sandwiched between two substrates 60 and 62. Here, the lower substrate 60 is a silicon single crystal wafer,
The transistor 63 is formed on the wafer, and the source electrode of the transistor is connected to the pixel electrode 64. This pixel electrode is made of a metal such as aluminum, and also functions as a light reflection layer. Opposite substrate 6
Reference numeral 2 is made of transparent glass, and a transparent electrode is provided inside. Further, an antireflection layer 66 made of a dielectric multilayer film is provided on the surface of the substrate 62 to prevent image quality deterioration due to surface reflection.

In FIG. 3, since the circuit configuration of the entire wafer is not known, it will be described with reference to FIG. FIG. 4 is a configuration diagram of a circuit built in the wafer, and circuits 71, 72, and 71 for driving a display unit 70 including pixels arranged in a matrix.
There are 73. Here, reference numeral 71 denotes a scan-side drive circuit that applies a gate pulse voltage to a row electrode group in which the gates of the transistors are connected for each row in a time-series manner. It is a control circuit that controls the circuit.

Since a polymer dispersed liquid crystal is used as the light scattering liquid crystal, its operation will be described with reference to FIG. The polymer dispersed liquid crystal has a structure in which a nematic liquid crystal 82 is encapsulated in an organic material 81, for example, polyvinyl alcohol. At this time, the nematic liquid crystal molecules are oriented horizontally on the wall surface of the capsule. Therefore, in the case of a polymer-dispersed liquid crystal having a slightly elliptical cross-sectional structure, light incident in the vertical direction in FIG. Will be more likely to show. On the other hand, when the voltage of the drive voltage source 83 is applied, the nematic liquid crystal molecules are oriented so that the major axis is oriented in the direction of the electric field as shown in the figure, and thus the incident light is incident from the major axis direction of the molecule.

At this time, in the polymer dispersion type liquid crystal selected so that the refractive index of the organic material 81 is substantially equal to the refractive index in the molecular long axis direction, at the interface of the capsule when no electric field is applied,
Since the refractive index of the organic material is different from that of the liquid crystal, light scattering occurs. When an electric field is applied, the refractive index of the organic material is substantially equal to the refractive index of the liquid crystal.

In the liquid crystal element having such a structure as shown in FIG. 4 using such a polymer dispersed liquid crystal, a pixel to which a sufficient electric field is applied by a transistor enters from above the element because the liquid crystal is transparent. The light is reflected by the reflective layer, which is almost 100% (actually, about 80% to 90%) of the pixel electrode, resulting in bright pixels on the screen. on the other hand,
When no electric field is applied, light is strongly scattered in the liquid crystal layer, so that the scattered light does not reach the screen, resulting in a dark display.

Since the intensity of scattering gradually changes as the voltage increases, halftone display can be performed by voltage modulation.

In the first embodiment described above, the use of the light-scattering type liquid crystal makes it possible to remove the polarizing plate which is indispensable for the TN type liquid crystal, so that the brightness can be approximately doubled. Further, by using a reflective liquid crystal element, a pixel electrode can be provided over a transistor or a wiring electrode, so that light use efficiency is increased. Therefore, a bright display can be realized with a lamp with low power consumption as compared with the conventional projection display. Further, since the reflection type projection optical system is used, the color separation optical system and the color synthesizing optical system can be shared, so that the size of the apparatus can be reduced.

Further, by incorporating the peripheral drive circuit on the silicon single crystal wafer, the number of connection points with the outside can be greatly reduced, and the effect of improving the reliability and simplifying the mounting to remarkably reduce the size of the device is remarkable. FIG. 6 shows a second embodiment of the present invention.

The light scattering type liquid crystal of this embodiment is different from that of the first embodiment in that the organic material 91 contains a nematic liquid crystal 92.
However, the nematic liquid crystal is not in the shape of a capsule (substantially spherical), and the gap between the organic materials is filled with the nematic liquid crystal as shown in FIG.

The optical behavior with respect to the presence or absence of an electric field is the same as that of the first embodiment. However, since there are many liquid crystal portions penetrating between the electrodes in the direction of the electric field, the driving voltage can be lower than that of the capsule-shaped polymer dispersed liquid crystal. It is a feature.

FIG. 7 shows a third embodiment of the present invention.

The light scattering type liquid crystal of this embodiment is a liquid crystal material having a smectic A phase as shown in FIG. The smectic A-phase liquid crystal has a focal
It takes an alignment state exhibiting light scattering properties called a conic structure. On the other hand, when an electric field is applied, the homeotropic structure 102 having the molecular long axes aligned in the direction of the electric field is adopted and the display becomes transparent, so that the display as described above can be achieved. In this embodiment, unlike the first and second embodiments, only the liquid crystal material is sealed between the electrodes, and the manufacturing method can be substantially the same as that using a conventional TN type liquid crystal.

FIG. 8 shows a fourth embodiment of the present invention.

In this embodiment, a switching circuit 111 for selecting and outputting one input from two inputs for each pixel by a plurality of transistors of each pixel is provided.
The switching circuit 111 reads display information input from the column electrodes 113 in response to a pulse voltage signal from the row electrodes 112, and selects either the display voltage V (on) or V (off) according to the read information. , The liquid crystal 114 is driven. Also, if a circuit that holds the read information once read is held until the next pulse voltage arrives, V (on) or V (off) is always applied to the liquid crystal, which is peculiar to the conventional example. Since there is no time for the circuit to be in an open state when viewed from the liquid crystal, the management of the impedance of the liquid crystal layer can be reduced. Moreover,
There is an effect that the storage capacitor 115 can be made unnecessary.

In this embodiment, since a two-input one-output switching circuit is used, only binary display is possible. However, the number of inputs of the switching circuit is increased, and the display information and the display voltage value are correspondingly increased. Thus, the extension to the multi-value display is obvious.

FIG. 9 shows a fifth embodiment of the present invention.

In this embodiment, each pixel has a sample / hold circuit S / H and further has an analog amplifier Amp.

The sample / hold circuit S / H reads and holds analog image information by a pulse voltage given from a row electrode. The function of driving the liquid crystal by amplifying the analog image information to a predetermined size is analog amplifier A.
mp, and the liquid crystal 123 is always driven by a low impedance voltage source as in the fourth embodiment.
This has the effect of reducing the impedance management of the liquid crystal layer and making the storage capacitor 124 unnecessary.

FIG. 10 shows a sixth embodiment of the present invention.

In this embodiment, not only the display unit 131 and its peripheral circuit 132 but also a frame memory 133 for storing display information for one screen and a control circuit including the control circuit are built in the silicon single crystal wafer. It was done.

With such a configuration, the external device (for example, a personal computer) can store the frame memory 13
Thirdly, the operation of writing the display information may be performed, and it is not necessary to generate the control timing and perform the time-series high-speed transmission of the image data, which are conventionally required.

FIG. 11 shows a seventh embodiment of the present invention.

This embodiment is an example of a method for mounting a liquid crystal element.
Dichroic prism 14 which is a color separation / synthesis optical system
1, an external lead terminal wiring is provided, and the electrical connection with the silicon single crystal wafer 142 is made as shown in the figure.
This is performed via a solder bump. So-called chip-on
This is performed by a glass method. Note that the liquid crystal is naturally disposed between the dichroic prism 141 and the silicon single crystal wafer 142, and the counter electrode 144 is connected to the liquid crystal layer or from the dichroic prism to the external circuit by a flexible flat cable 145. Performed by

By adopting such a mounting method,
The packaging of the liquid crystal element is simplified, and the size of the device can be reduced.

FIG. 12 shows an eighth embodiment of the present invention.

In this embodiment, the glass substrate 151 on the light incident side of the liquid crystal element is inclined with respect to the optical axis. In this case, the light component reflected on the surface of the glass substrate 151 and originally deteriorating the display quality is deviated from the optical axis.
Since it does not reach the screen, deterioration of display quality can be prevented. In addition, through the liquid crystal layer 152 in a transparent state,
The light reflected on the silicon single crystal wafer travels along a predetermined optical axis, and does not hinder the display operation.

FIG. 13 shows a ninth embodiment of the present invention.

This embodiment is an example of a projection optical system, and is characterized in that a half mirror 161 is used instead of a reflecting mirror as compared with the first embodiment. At this time, the white light emitted from the light source 162 is made substantially parallel by the lens 163. This parallel light is reflected by the half mirror 161 to the left by almost 50%, and enters the dichroic prism 164 which is a color separation / synthesis optical system. The operations of the dichroic prism and the liquid crystal elements 165-R, 165-G, 165-B are the same as in the first embodiment.

The light reflected by the liquid crystal element and recombined is
The light again enters the half mirror 161, and approximately 50% of the incident light
% Is projected onto the screen by the projection lens 166.

Although the present optical system has a disadvantage of large light loss, the optical system is simplified, and the effect of reducing the size and the cost is remarkable.

FIG. 14 shows a projection type liquid crystal display device with a built-in lamp adjustment function.

In this figure, the same parts as those in FIG. 1 are given the same numbers.

In this embodiment, a mechanism for automatically adjusting the lamp position, which is necessary when replacing the lamp 11 as a light source, is provided.

Since the lamp 11 is considered to be the shortest-required replacement part in the optical system, this replacement is an essential matter. This exchange usually involves complicated position adjustment work, and thus has to be performed by a specialist. However, in this embodiment, the position fine adjustment mechanism 1 for finely adjusting the position of the lamp holder
702, a driving circuit 1703 for driving the same, a light detecting unit 1704, a light detecting unit moving mechanism 1750, and a light detecting unit driving circuit 1706 are provided, and automatic position adjustment can be performed.

Next, the operation will be described.

A feature of the present optical system is that there is a condensing point at a point P in the optical system. Therefore, the position may be adjusted so that the light converging point is accurately located at the point P when replacing the lamp. Therefore, the light detection unit 1704 can be placed at the point P. Therefore, the light detection unit 170 normally located at a position that does not obstruct the optical path is used.
The light detection movement mechanism 1705 that moves the light source 4 to the point P when replacing the lamp and the drive circuit 1706 thereof are operated. The light detection unit 1704 has a light detection element smaller than the converging spot diameter at point P, and the time when the amount of light detected by this light detection element is the largest is when the light is condensed exactly on point P. Therefore, the light detection output is sent to the lamp position fine movement mechanism drive circuit 1703 to finely adjust the lamp position.

Since it is usually difficult to determine the maximum light quantity, the optimum light quantity range is stored in advance according to the type of the lamp 11 to be used, and the adjustment is completed when the detected light quantity falls within the light quantity range. You can also.

Further, the output of the photodetector and the optimum light amount range are displayed so that the lamp position fine movement mechanism can be manually driven, so that even a layman can easily perform fine adjustment according to the display.

After the lamp position is automatically or manually adjusted in this way, if the light detecting section 1704 is returned to the initial position, the light path will not be disturbed and the function as a display will be obtained. It should be noted that the moving amount of the photodetector is also uniquely determined if the optical system is determined, and thus can be manually performed. Further, the present photodetector can be used for optical axis adjustment and the like.

It should be noted that the ramp position fine movement mechanism 1702 can be one that can finely move one-dimensionally, two-dimensionally or three-dimensionally.

Further, in this embodiment, the reflection type liquid crystal display device has been described, but it goes without saying that the light detection device for lamp adjustment of the present invention is also provided in the transmission type liquid crystal display device if a condensing point is provided in the device. The lamp can be replaced and the optical axis can be easily adjusted.

In the above embodiment, the amount of light detected by the photodetector is the amount of light, but the intensity of light may be measured.

According to the embodiment described above, since the lamp can be easily replaced, it is suitable for use in places where there is no professional such as home use.

[0070]

According to the present invention, the light use efficiency of the liquid crystal portion can be almost doubled by using a light scattering type liquid crystal which does not require a polarizing plate, and the effective display area can be increased by using a reflection type element. And a bright projection display with low power consumption can be realized.

Further, by using the reflection type projection optical system, the size of the optical system can be reduced.

Further, by using a liquid crystal element in which an active element such as a transistor is formed on a silicon single crystal wafer, a peripheral drive circuit and various control circuits can be built in the liquid crystal element. Improvement, simplification of mounting, and downsizing can be achieved.

Further, by providing a converging point in the projection device, it is possible to easily measure the light intensity and light amount and to easily adjust the displacement of the optical axis due to lamp replacement or vibration. The usability has been improved.

[Brief description of the drawings]

FIG. 1 is an optical system layout diagram of a liquid crystal projection display according to a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram showing one pixel of the liquid crystal element of the present invention.

FIG. 3 is a cross-sectional structural view of a liquid crystal element.

FIG. 4 is a block diagram of a circuit built in the liquid crystal element.

FIG. 5 is a schematic diagram of the first embodiment for explaining the operation of the liquid crystal used in the present invention.

FIG. 6 is a schematic diagram of a second embodiment for explaining the operation of the liquid crystal used in the present invention.

FIG. 7 is a schematic diagram of a third embodiment for explaining the operation of the liquid crystal used in the present invention.

FIG. 8 is an equivalent circuit diagram of one pixel according to a fourth embodiment of the present invention.

FIG. 9 is an equivalent circuit diagram of one pixel according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a built-in circuit according to a sixth embodiment of the present invention.

FIG. 11 is a schematic diagram illustrating mounting of a liquid crystal element according to a seventh embodiment of the present invention.

FIG. 12 is a sectional view of a liquid crystal element according to an eighth embodiment of the present invention.

FIG. 13 is an optical system layout diagram of a projection display according to a ninth embodiment of the present invention.

FIG. 14 is a configuration diagram of a projection type display with a lamp adjustment function of the present invention.

[Explanation of symbols]

11 light source, 12 reflecting mirror, 13, 16, 17 lens, 14 color separation / synthesis optical system, 15-R, 15-G, 1
5-B: liquid crystal element, 18: peripheral driving circuit.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/74 H04N 5/74 K (72) Inventor Yoshiro Mikami 4026 Kuji-cho, Hitachi City, Hitachi, Ibaraki, Ltd. Hitachi Research Laboratory, Hitachi (72) Inventor Hideo Sato 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd. (72) Minoru Hoshino 4026 Kuji-machi, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. In the laboratory

Claims (8)

[Claims] 1. A liquid crystal display device having a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates, wherein one of the pair of substrates is a semiconductor substrate, and the semiconductor substrate includes A display portion including a plurality of pixels and a driving circuit portion for driving the display portion are provided, and the other substrate of the pair of substrates is a transparent substrate having a transparent electrode, and is provided between the semiconductor substrate and the glass substrate. , A liquid crystal display device having a liquid crystal layer containing a light dispersion type liquid crystal substance that changes a transmission scattering state according to an applied voltage. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal in the liquid crystal layer is a polymer dispersed liquid crystal having a structure in which a nematic liquid crystal is included in an organic material. 3. The liquid crystal display device according to claim 2, wherein said polymer dispersed liquid crystal has a structure in which a nematic liquid crystal is encapsulated in an organic material. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal in the liquid crystal layer is a scattering type liquid crystal using a smectic A phase liquid crystal material. 5. A switching circuit having a multi-input terminal and one output terminal, said pixel being connected to said multi-input terminal,
A plurality of voltage input lines for supplying different voltages, wherein the switching circuit switches inputs from voltage input lines connected to the multiple input terminals in accordance with a signal from the drive circuit unit. 2. The liquid crystal display device according to claim 1, wherein display is performed according to a value state. 6. The liquid crystal display device according to claim 1, further comprising a pixel electrode, a sample hold circuit, and an analog amplifier provided between said sample hold circuit and said pixel electrode for each pixel. 7. A glass substrate having a transparent electrode formed on one side thereof,
A liquid crystal display device including a liquid crystal display element in which a liquid crystal layer is sealed between a silicon substrate and a liquid crystal display device. And a liquid crystal display device comprising a frame memory for storing display information. 8. The liquid crystal display device according to claim 7, wherein said frame memory stores display information for one screen.