KR970000836B1 - Liquid crystal light valve having capability of providing high-contrast image - Google Patents

Abstract

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Description

Liquid Crystal Light Valves That Can Provide High Contrast Images

1 is a cross-sectional view schematically showing a liquid crystal light valve according to a first embodiment of the present invention.

2 is a schematic diagram of a drive unit included in the liquid crystal light valve shown in FIG.

3 is a perspective view showing the connection of the LED array shown in FIG.

4 is a schematic diagram showing a first embodiment of a projection image display apparatus to which the liquid crystal light valve shown in FIG. 1 is applied.

5 is a sectional view schematically showing a liquid crystal light valve according to a second embodiment of the present invention.

6 is a cross-sectional view showing a substrate including an optical waveguide and an LED unit included in a liquid crystal light valve according to a third embodiment of the present invention.

7 is a sectional view schematically showing a liquid crystal light valve according to a fourth embodiment of the present invention.

8 is a perspective view schematically showing a liquid crystal light valve according to a fourth embodiment of the present invention.

9 is a cross-sectional view taken along the line A-A in FIG.

10 is a schematic view of a drive unit included in the liquid crystal light valve shown in FIGS. 8 and 9;

FIG. 11 is a sectional view schematically showing a liquid crystal light valve according to a sixth embodiment of the present invention. FIG.

FIG. 12 is a schematic diagram showing a drive unit included in the liquid crystal light valve shown in FIG.

13 is a perspective view showing in detail the connection of the LED array shown in FIG.

14 is a sectional view schematically showing a liquid crystal light valve according to a seventh embodiment of the present invention.

FIG. 15 is a schematic diagram showing a two-dimensional optical operation element applied to a liquid crystal light valve according to an eighth embodiment of the present invention. FIG.

* Explanation of symbols for main parts of the drawings

10,40,80: liquid crystal light valve 11,41,63,81: optical waveguide

12a, 12b, 42a, 42b, 82a, 82b: glass substrate 13, 43, 82: transparent electrode

14,44: cladding layer 14,45,85: metal film

16,46,86: photoconductive layer 17,47,87: dielectric layer (dielectric mirror)

19, 49, 89: electrodes for data transmission 20a, 20b, 40a, 40b, 90a, 90b: alignment layer

21, 51, 91: liquid crystal layer 25: LED array

26 drive circuit 27 optical lens array

28: reflector 31: lamp

32: lens 33: polarized splitter

61 substrate 62 LED device

63,81: Optical waveguide 64a, 64b: LED electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid crystal light valves used for projection display devices, spatial light modulators, and coherent photocalculators.

An address system for forming an image on a liquid crystal valve according to a signal representing an image (hereinafter referred to as an image signal) includes an electric address system, a laser column address system or an optical address system.

In the electric address method, the liquid crystal ride valve of the multiplex drive system is simply arranged to have a plurality of scan electrodes and signal electrodes arranged in a matrix state. This liquid crystal light valve is composed of scan electrodes X ₁ , X ₂ ... X _n and signal electrodes Y ₁ , Y ₂ ... Y _m arranged in the X and Y directions, respectively. It is arranged to selectively apply a voltage on the pixels and to transmit the scan signal and the data signal over the wire.

In the optical address system, the liquid crystal layer and the photoconductor layer arrange a liquid crystal light valve so as to be placed between two glass substrates having transparent electrodes to directly address the liquid crystal through the effect of irradiated light.

A typical example of an optical address type liquid crystal light valve is described in J., Greenberg, A., et al. Jay Copson, W. Dealer, L. Pras, d. Boshel, G. A New Real-Time Noncoherent To Coherent Record Image Converter by J. Grinberg, A. Jacopson, W. Miller, L. Frasss, D. Boswe, G. Myer Coherent Write Image Convereter and The Hybrid Field Effect Liquid Crystal Light Valve.

In this example, the photo-address liquid crystal light valve is arranged to have a pair of organic substrates, two transparent electrodes, a photoconductor layer, a dielectric mirror, two alignment films, a sealing member, a liquid crystal layer and an alternating current power source. The AC power supply acts to apply a voltage between the transparent electrodes. When the address (write) light beam is incident on one glass substrate, the impedance of the photoconductor layer is reduced in the light irradiation area (bright area), so that a voltage can be applied from the AC power source to the liquid crystal layer.

On the other hand, in another region where light is not irradiated (dark), the impedance of the photoconductor layer of the photoconductor layer is kept constant so as not to be applied to the liquid crystal layer.

Due to the difference between the bright state and the dark state, image information is formed corresponding to the address light. This image information can be read out by the read light rays.

This type of liquid crystal light valve can be applied to a projection display device, a coherent photo-operating element, and the like.

As another example, an address type liquid crystal light valve in which an electric address system and an optical address system are combined is proposed. As disclosed in Japanese Patent Laid-Open No. 2-134617, the data signal in the electric address system is transmitted using an optical signal.

The above-mentioned electric address type liquid crystal light valve of the simple multiplex driving type is arranged to apply a divided voltage on the pixels except the display pixels. Therefore, such a known light valve has a problem that the display contrast is lowered. The time when the data signal used to control the display state is applied to the display pixels is a constant time defined by the duty ratio. For the rest of the time, a data signal is applied to the display pixels irrelevant to the control of the display state. Therefore, the liquid crystal has a problem in that it responds to the transmitted data signal when it is not selected. To solve this problem, a method called voltage averaging method is commonly used in simple matrix drive systems with matrix electrodes.

However, as the number n of scan electrodes increases, the margin of the operating voltage in the voltage averaging method decreases. When the liquid crystal material used has a constant light ray characteristic, the number n of scan electrodes for maintaining a practical display level is limited. Therefore, it becomes difficult to provide a higher resolution or a larger screen than the arrangement of the held scan electrodes using voltage averaging.

In addition, in the known electric address type liquid crystal light valve, it is impossible to realize a large size device or a high density device because the resistance and capacitance of the wire delay the signal waveform.

On the other hand, the known liquid crystal light valve of the optical address type system requires an address light source such as a CRT or a liquid crystal panel. As a result, a problem arises in that the size of the entire apparatus cannot be reduced.

In an address system (see Japanese Patent Laid-Open No. 2-134617) in which a known electric address system and a known light irradiation address system are combined, the waveform of the data signal is converted into a change in the light intensity and recorded in the photoconductor layer. do. Therefore, there is a need to provide a highly sensitive photoconductor layer that is capable of sustaining minute changes in light intensity. The photoconductor layer should have a uniform sensitivity distribution in order to display the image uniformly on the screen.

Accordingly, it is an object of the present invention to provide a liquid crystal light valve capable of forming a high contrast image and realizing miniaturization in size.

In order to achieve the above object, the liquid crystal light valve of the present invention comprises: first substrates 12a, 42, 82a, 101, 203, 301 having first transparent electrode means 13, 43, 83, 106, 206, 308, 311 thereon; Second substrates 12b, 42b, 82b, 113, 212, 316 having second transparent electrode means thereon; A liquid crystal layer 21, 51, 91, 111, 215, 319 provided between the first substrate and the second substrate; A photoconductor layer (16,46,86,107,209,313) adapted to change impedance in response to incident light thereon, the photoconductor layer comprising: a photoconductor layer disposed between the liquid crystal layer and the first substrate; A liquid crystal light valve for forming an image in response to a data signal disposed on the same surface as the first substrate of the liquid crystal layer and including a plurality of light waveguides extending in a first direction. The second transparent electrode means includes a plurality of stripe electrodes extending along a direction crossing the first direction, and an optical scan signal supply means is connected to the optical waveguide to emit light to the photoconductor layer when in use. The data signal supply means is connected to the second electrode to apply a data signal to the second electrode when in use.

According to another aspect of the invention, the optical waveguide is formed in a stripe shape on the first substrate. The transparent electrode formed on the second substrate is patterned in the form of a stripe.

According to another aspect of the invention, the optical waveguide is formed of a polymer waveguide.

According to another aspect of the invention, the optical waveguide is formed of an electroluminescent element.

According to another aspect of the invention, the first substrate comprises two small substrates. Further, the optical waveguide includes a first optical waveguide formed on one of the two small substrates and a second optical waveguide formed on the other small substrate.

According to another aspect of the present invention, the small electrode formed on the liquid crystal layer is formed of a fiber plate.

According to another aspect of the present invention, at least one of the first and second optical waveguides is formed of an electroluminescent element.

In operation, when light rays are applied from the first substrate to the photoconductor layer, the impedance of the photoconductor layer is changed to select the appropriate scan lines. The impedance of the photoconductor layer on the selector to which light is applied from the optical waveguide is smaller than the impedance of the liquid crystal layer. This allows almost all of the data signals applied to the transparent electrode provided on the first substrate on the liquid crystal layer to be applied. On the other hand, on the unselected portion of the photoconductor layer where no light is applied from the optical waveguide, the impedance of the photoconductor layer is larger than the impedance of the liquid crystal layer. Therefore, the data signal irrelevant to the control of the display state is prevented from being applied to the liquid crystal layer.

As described above, unlike the known liquid crystal light valve of the simple multiplex drive system that transmits the scan signal through the wire, since the scan signal is transmitted to the light sent to the optical waveguide, in such a liquid crystal light valve, The data signal is not always applied to the corresponding unselected liquid crystals. Therefore, the bias ratio of the voltage applied to the liquid crystal layer from the selection portion of the photoconductor layer to the liquid crystal layer from the non-selection portion of the photoconductor layer is increased. Accordingly, the liquid crystal light valve can form a high contrast image.

In addition, since only one light source, i.e., a liquid crystal light valve, is required, the size of the entire apparatus is reduced.

Further, the scan signal (pulse waveform) is converted to the on / off state of light before writing to the photoconductor layer. Therefore, the photoconductor layer only needs to be able to exhibit impedance above a certain threshold. The photoconductor layer does not need to have high performance, unlike the photoconductor layer in the technique of changing the data signal to variable light intensity when a data signal is written thereon. This is advantageous in the manufacture of the device.

According to the invention, the scanning signal is transmitted via light sent from an electroluminescent element which is possible as an optical signal source for scanning. Accordingly, the liquid crystal light valve of the present invention, unlike the known liquid crystal light valve of the simple matrix drive system, is arranged as a matrix electrode for transmitting the scan signal through the wire, the data signal to the liquid crystal corresponding to the non-selected portion of the photoconductive layer layer Do not authorize. This means that the bias ratio of the voltage applied to the liquid crystal from the selection portion of the photoconductor layer to the liquid crystal layer from the non-selection portion of the photoconductor layer is increased. This enables the liquid crystal light valve of the present invention to form an image having high contrast.

The optical waveguide is formed on two substrates included in the first substrate. This eliminates the spacing between adjacent scan lines and increases the number of scan lines, thereby improving resolution and numerical aperture.

Of the substrates on both sides of the first substrate, the substrate on one side of the liquid crystal layer is formed of a fiber board to prevent crosstalk caused by leakage of light.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

A liquid crystal light valve according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 4. 1 is a sectional view schematically showing this liquid crystal light valve.

As shown in FIG. 1, 10 is a liquid crystal light valve, and the optical waveguide 11, the glass substrates 12a and 12b, the transparent electrode 13, the cladding layer 14, the metal film 15, and the photoconductor It is arranged to have a layer 16, a dielectric mirror 17, an electrode for data transmission 19, alignment films 20a and 20b, and a liquid crystal layer 21.

The optical waveguide 11 is formed in the shape of a stripe (thin line) on the glass substrate 12a by heat or development based on ion exchange. The optical signal for scanning is transmitted along the optical waveguide 11.

According to this embodiment, for example, a multi-mode optical waveguide such as the optical waveguide 11 is formed by thallium (T1) ion exchange so as to guide even light having poor directivity sent from a light emitting diode or the like. Instead, silver (Ag) ions can be used.

The transparent electrode 13 is formed of indium oxide (ITO: indium tin oxide) doped with tin. The transparent electrode 13 is formed on the optical waveguide 11 and the glass substrate 12a by the sputtering method through the cladding layer 14 located therebetween. The transparent electrode 13 may be patterned in a stripe shape so as to overlap the optical waveguide 11.

The cladding layer 14 is deposited by a sputtering technique between both the glass substrate 12a and the optical waveguide 11 and the transparent electrode 13. This is formed because the refractive index of the transparent electrode 13 is larger than that of the optical waveguide 11. The material of the cladding layer 14 is silicon dioxide (SiO ₂ ), which is a dielectric having a low refractive index. The thickness of the SiO ₂ film needs to be set so that appropriate light leaks from the optical waveguide 11 serving as a light emitting source. The thickness is preferably in the range of 500 to 5000 mm 3. In this embodiment, the thickness of SiO ₂ is 3000 kPa.

On the rear surface of the glass substrate 12a, that is, on the side opposite to the surface on which the optical waveguide 11 is formed, a metal film 15 for blocking light applied anywhere other than the optical waveguide 11 is disposed.

The material of the metal film 15 is aluminum (A1), molybdenum (Mo), or the like. In such a case, a pigment dispersed light shielding film which is often used for a color filter or the like of a liquid crystal panel may be used instead of the metal film 15.

On the transparent electrode 13, a photoconductor layer 16 is formed to receive light from the optical waveguide 11. The photoconductor layer 16 is formed of amorphous silicon hydroxide (a-Si: H) by plasma CVD (chemical vapor deposition).

The photoconductor layer 16 may be formed so that light has a characteristic of changing impedance according to the irradiation amount instead of a-Si: H. The photoconductor layer 16 includes bismuth silicate (Bi ₁₂ SiO ₂₀ ), cadmium sulfide (Cds), amorphous silicon hydride carbide (a-SiC: H), and amorphous silicon hydride (a-SiO: H). , And amorphous silicon oxynitride (a-SiN: H) may be used.

As a technique of suppressing dark current in the photoconductor layer 16, there is a method of forming a stop type electrode structure by using a selective crystal transmittance of a carrier. For example, when the photoconductor layer 16 is formed of a-Si, a thin n-type layer doped with phosphorus (P) and a thin p-type layer doped with boron (B) (both layers are made of a-Si) It is coupled to have a back-to-back diode structure of a pin type diode structure or a pinip type diode structure. Alternatively, the low electrode structure can be formed by using Schottky junction or heterojunction with a material having wide-gap characteristics. An extremely thin SiO ₂ or SiN _X film or the like of about 50 to 300 kPa may be disposed on one or both surfaces of the photoconductor layer 16 as necessary.

The dielectric mirror 17 is formed on the photoconductor layer 16 by electron beam deposition. The dielectric mirror 17 is made of a multilayer film formed by alternately stacking a titanium dioxide (TiO ₂ ) layer and an SiO ₂ layer.

In order to prevent the read light 18 from leaking into the photoconductor layer 16 through the dielectric mirror 17, a light shielding layer may be provided between the dielectric mirror 17 and the photoconductor layer 16. As the light shielding layer, a carbon dispersed organic thin film, cadmium telluride (CdTe), and aluminum oxide (Al ₂ O ₃ ) electroplated with silver can be used.

On the glass substrate 12b opposite the glass substrate 12a, an electrode 19 for data transmission is arranged, which is formed of ITO deposited on the substrate 12b, and sputtering technique. Is patterned into a stripe pattern.

On the dielectric mirror 17 and the electrode 19 for data transmission, a pleimide film is spin coated to sinter the coated film to form alignment films 220a and 20b, respectively. Molecular alignment treatment is performed on the surfaces of the alignment films 20a and 20b by a polishing method.

Subsequently, the glass substrates 12a and 12b are pasted through spacers (not shown) so that the data transfer electrode 19 and the scanning optical waveguide 11 are vertically positioned. The liquid crystal layer 21 is formed by injecting liquid crystal into a space formed of the alignment layers 20a and 20b and the spacer (s). The liquid crystal used should be chosen such that its impedance is greater than the portion selected for the scan line of the photoconductor layer 16 but less than the remaining portion not selected for the scan line of the photoconductor layer 16.

In the liquid crystal light valve having the above-described configuration, since the impedance of the liquid crystal layer 21 is much larger than the impedance of the portion of the photoconductor layer 16 selected as the scanning line by the irradiated light, the impedance of the data signals applied between the electrodes Most of them may be applied to the liquid crystal layer 21. Since the impedance of the liquid crystal layer 21 is smaller than the impedance of the remaining portion of the photoconductor layer 16 to which light is not irradiated, no data signal is applied to the liquid crystal layer 21.

Thus, according to this embodiment, the scanning signal is transmitted as light from the optical waveguide. Unlike known liquid crystal light valves of simple multiplex drive systems having matrix electrodes for transmitting scan signals over electrical wiring, data signals are not always applied to the non-selected portions of the photoconductor layer.

As a result, the bias ratio of the voltage applied to the liquid crystal layer from the non-selection portion of the photoconductor layer to the liquid crystal layer from the selection portion of the photoconductor layer becomes larger. Therefore, when the light valve of the present embodiment is used, a high contrast image can be formed, and since a delay does not occur in the signal waveform due to the wiring resistance or capacitance, a large device or a high density device can be realized.

Furthermore, the light valve of this embodiment operates to increase the margin of the operating voltage used in the voltage averaging method, which voltage is defined by the normal number of scan lines. As a result, the light valve makes it possible to provide higher resolution or larger screens.

In addition, the waveform of the data signal can be modified to display gray scales.

In the above-described embodiment, the optical waveguide 11 is formed at the same level as one side of the glass substrate 12a. In such a case, the optical waveguide can be formed completely inside the glass substrate.

FIG. 2 schematically shows a drive unit of the liquid crystal light valve 10 shown in FIG. 2 does not show a signal or a timing generating unit to simplify the description.

As shown in FIG. 2, the drive unit of the liquid crystal light valve 10 is configured to have an LED (light emitting diode) array 25 for scanning signals and a drive unit 26 for driving the transparent electrode 19. As shown in FIG. Instead of the LED array 25, a semiconductor laser LD may be used.

The LED array 25 is connected to the liquid crystal light valve 10 so that the light pulse signal is guided from the LED array 25 to the liquid crystal light valve 107.

3 is a perspective view showing in detail the connection of the LED array 25 shown in FIG.

As shown, light emitted from the LED array 25 is guided through the optical lens array 27 to the optical waveguide of the liquid crystal light valve 10. In another connection manner, the end of the optical waveguide can be directly connected to the phosphor surface of the LED array 25 without using the optical lens array 27.

The reflector 28 serves to reflect the light leaked to the end of the optical waveguide so that the light is effectively guided to the photoconductor layer. The reflector is made of Al, Ag, or the like and corresponds to the metal film 15 shown in FIG.

4 schematically shows an embodiment of a projection display device in which the liquid crystal light valve of FIG. 1 is used.

As shown, the projection display device is configured to include a liquid crystal light valve 10, a lamp 31, a lens 32, a polarization beam splitter 33, a lens 34, and a screen 35. Light emitted from the lamp 31 is applied to the liquid crystal light valve 10 through which the image is formed through the polarization beam splitter 33 of the lens 32. When light is transmitted through a portion of the liquid crystal layer of the liquid crystal light valve 10 in which the molecular alignment state changes, the polarization direction of the light is changed due to the electro-optic effect. Therefore, the light reflected by the liquid crystal light valve 10 may pass through the polarization beam splitter 33. The reflected light extends through the lens 34 so that the image formed in the liquid crystal light valve 10 is projected onto the screen 35.

Therefore, when an address light source for a CRT or a liquid crystal display is required, unlike the liquid crystal light valve of the known optical address system, the liquid crystal light valve of this embodiment does not require such a light source. Therefore, the liquid crystal light valve of this embodiment contributes greatly to reducing the size of the entire apparatus.

The operating mode of the liquid crystal used in this embodiment is a hybrid field effect mode of nematic liquid crystal. As another mode of operation, a twisted nematic mode, a supertwisted nematic mode or an electrically controlled birefingent mode may be used.

Furthermore, ferroelectric liquid crystals, antiferroelectric liquid crystals, and sematic liquid crystals having an electro-clinic effect may be used. In addition, the phase transfer mode with the nematic liquid crystal, the operation scattering mode or the guest-host mode, or the liquid crystal composite film or the sematic liquid crystal can be made to remove the flat beam splitter 33.

Meanwhile, the liquid crystal light valve according to the second embodiment of the present invention will be described.

5 is a cross-sectional view schematically showing a second embodiment of the liquid crystal light valve according to the present invention. As shown, the liquid crystal light valve 40 includes an optical waveguide 41, glass substrates 42a and 42b, a transparent electrode 43, a cladding layer 44, a metal film 45, and a photoconductor layer 46. And dielectric mirror 47, data transfer electrode 49, alignment films 50a and 50b, and liquid crystal layer 51.

The optical waveguide 41 is formed in the shape of a stripe (thin line) on the glass substrate 42a by an ion exchange method. Scanning optical signals are transmitted along the optical waveguide 41. According to this embodiment, a multimode optical waveguide formed by a thallium (Tl) ion exchange method is used to guide light having poor directivity such as light emitted from an LED. In this case, silver (Ag) ions can also be used.

The transparent electrode 43 is formed of indium oxide (ITO) doped with tin. The transparent electrode 43 is formed by sputtering on the optical waveguide 41 and the glass substrate 42a through the cladding layer 44 positioned therebetween.

The pattern of ITO which forms the transparent electrode 43 is located so that it may be parallel and shifted by 1/2 pitch in the stripe form of the optical waveguide 11. The other part of the transparent electrode except ITO is formed of an insulator 52 such as SiO ₂ to prevent a short circuit between the transparent electrodes 43. Therefore, the optical waveguide 41 and the insulator 52 overlap with the cladding layer 44 therebetween.

The cladding layer 44 is deposited by sputtering between the transparent electrode, the optical waveguide 41 formed on the substrate 42a, and the glass substrate 42a. This cladding layer 44 is provided because the refractive index of the transparent electrode 43 is larger than that of the optical waveguide 41.

The cladding layer 44 is made of SiO ₂ or the like made of a dielectric having a low refractive index. The thickness of the SiO ₂ film should be set so that appropriate light leaks which functions as a light source. The thickness is preferably in the range of 500 to 5000 mm 3. In this embodiment, the thickness of SiO ₂ is 3000 kPa.

On the back surface of the glass substrate 42a, that is, on the side opposite to the surface on which the optical waveguide 41 is formed, a metal film 45 for blocking light applied anywhere other than the optical waveguide 41 is deposited.

The material of the metal film 45 is silver (Ag), aluminum (Al), molybdenum (Mo), or the like. Alternatively, a pigment-jet light shielding film which is often used for color filters and the like of liquid crystal panels may be used instead of the metal film 45.

On the transparent electrode 43, the photoconductor layer 46 is deposited so as to receive light from the optical waveguide 41. The photoconductor layer 46 is made of amorphous silicon hydride (a-Si: H) by plasma CVD (chemical vapor deposition).

The photoconductor layer 46 may be formed to have a characteristic in which impedance changes according to the irradiation amount of the ratio instead of a-Si: H. Other materials of the photoconductor layer 46 include bismuth silicate (Bi ₁₂ SiO ₂₀ ), cadmium sulfide (Cds), amorphous silicon hydride carbide (a-SiC: H), and amorphous silicon hydride (a-SiO: H). , And amorphous silicon oxynitride (a-SiN: H) may be used.

As a technique of suppressing dark current in the photoconductor layer 46, it is possible to form a stop type electrode structure by selectively using a permeability of a carrier. For example, when the photoconductor layer 46 is formed of a-Si: H, the thin n-type layer doped with phosphorus (P) made of a-Si and the p-type layer doped with boron (B) are back-to-back with pinip structure. It is coupled to have a diode structure. Alternatively, there is also a method of forming a low electrode structure using a schottky junction, heterojunction with a material having a wide gap characteristic, or the like. An extremely thin SiO ₂ or SiN _X film or the like, such as 50 to 300 GPa, can be deposited on one or both surfaces as necessary.

The dielectric mirror 47 is formed on the photoconductor layer 46 by electron beam deposition. The dielectric mirror 47 is made of a multilayer film formed by alternately stacking a titanium dioxide (TiO ₂ ) layer and an SiO ₂ layer.

A light shielding layer may be provided between the dielectric mirror 47 and the photoconductor layer 46 to prevent the read light 48 from leaking into the photoconductor layer 46 through the dielectric mirror 47. As the light shielding layer, a carbon dispersed organic thin film, cadmium telluride (CdTe), and aluminum oxide (Al ₂ O ₃ ) electroplated with silver can be used.

On the glass substrate 42b opposite to the glass substrate 42a, a data transfer electrode 49 is disposed. The data transfer electrode 49 is formed on the substrate 42b in the form of a stripe of ITO deposited by sputtering. It is formed patterned on.

On the dielectric mirror 47 and the data transmission electrode 49, a polyimide film is spin coated and the coated film is sintered to form alignment films 50a and 50b, respectively. Molecular alignment treatment is performed on the surfaces of the alignment films 50a and 50b by a polishing method.

Subsequently, the glass substrates 42a and 42b are pasted through spacers (not shown) so that the data transmission electrode 49 and the scanning optical waveguide 41 are vertically positioned. The liquid crystal layer 51 is formed by injecting liquid crystal into the space defined by the alignment layers 50a and 50b and the spacer (s). The impedance of the liquid crystal used should be chosen to be larger than the portion of the photoconductor layer 46 selected as the scan line but smaller than the portion of the photoconductor layer 46 not selected as the scan line.

In the liquid crystal light valve having the above-described configuration, since the impedance of the liquid crystal layer 51 is much larger than the impedance of the portion of the photoconductor layer 46 selected as the scan line by the irradiation of the ratio, the data signal applied between the electrodes Most of these may be applied to the liquid crystal layer 51. Since the impedance of the liquid crystal layer 51 is smaller than the impedance of the remaining portion of the photoconductor layer 46 to which light is not irradiated, the data signal is not applied to the liquid crystal layer 51.

The liquid crystal light valve 40 causes one photoconductor layer 46 selected as a scanning line to be in contact with two scanning transparent electrodes 43 by the irradiation of light, and one main line in such a manner that the scanning line is divided into two. Synchronous scanning is performed so that a data signal is applied only to the transparent electrode 42 used. The liquid crystal light valve according to the present embodiment provides a high contrast image, and its resolution is also doubled.

In the above-described embodiment, the optical waveguide 41 is formed on the same surface as one surface of the glass substrate 42a. In this case, the optical waveguide can be formed completely inside the glass substrate.

The liquid crystal light valve according to the second embodiment has the same drive unit as the liquid crystal light valve according to the first embodiment. The configuration of the connection portion of the LED array included in the second embodiment is also the same as that of the connection portion of the first embodiment. The configuration of the projection display device using the liquid crystal light valve 40 and the operation mode of the liquid crystal are also the same as those of the first embodiment shown in FIG.

Next, another liquid crystal light valve according to the third embodiment of the present invention will be described.

As described above, the drive unit of the liquid crystal light valve of the first embodiment includes an LED array 25 serving as the scanning optical signal source shown in FIG. However, in this configuration, it is required to position the end of the optical waveguide very accurately with respect to the LED array. To remedy this problem, the liquid crystal light valve according to the third embodiment is formed so that the LED unit having the LED array is located adjacent to the same substrate as the optical waveguide.

6 is a cross-sectional view showing a substrate on which an optical waveguide and an LED unit are formed in the liquid crystal light valve of the third embodiment of the present invention.

As shown, the LED unit 62 and the optical waveguide 63 formed on the substrate 61 made of silicon single crystal are formed adjacent to each other. The LED unit 62 is made of a-Si _X C _1-X : H and has a pin structure. Using this material, it is possible to form the LED unit 62 at a relatively low temperature and consequently to provide an LED unit with high brightness. In addition, if a buffer layer made of GaP or the like is provided and the substrate used does not contain silicon, an Al _X Ga _1-X As-based LED may be used.

In this case, the phosphorescent wavelength range of the LED included in the LED unit 62 can be changed by adjusting the composition ratio X of the Al _X Ga _1-X As system. Therefore, depending on the sensitivity of the photoconductor layer, the LED can change its emission wavelength, which is advantageous for improving performance.

An optical waveguide 63 is formed to have a cladding layer 66 composed of the core layer 65 and the SiO ₂ consisting of SiO ₂ -GeO _2. SiO optical waveguide 63 consisting of a _2-based material is formed by a CVD method based on oxidation of SiC ₁₄ gas and ₁₄ gas GeiC. As another means, a flame deposition technique is used. With this technique, SiO ₂ -TiO ₂ formed of TiC ₁₄ gas can be used as the core layer instead of GeC ₁₄ initiation.

LED electrodes 64a and 64b are provided on the upper and lower portions of the LED unit 62. When using an LED composed of a-Si _X -C _1-X , a transparent electrode or a metal electrode can be used as the LED electrodes 64a and 64b. When using an LED made of Al _X Ga _1-X As, a substrate 61 made of single crystal silicon may be used as an electrode.

As shown, the LED unit 62 and the optical waveguide 63 are formed to be adjacent to each other on the same substrate 61. Thus, the light emitted from the LED unit 62 is guided to the optical waveguide 63 located on the side of the LED unit 62.

That is, instead of the glass substrates 12a and 42a in which the optical waveguides 11 and 41 are formed in the first and second embodiments, the liquid crystal light valve according to the fourth embodiment is an LED as described above. Provided is a substrate on which a unit 62 and an optical waveguide 63 are formed. The rest of the configuration of the liquid crystal light valve of the third embodiment is basically the same as that of the liquid crystal light valve according to the first and second embodiments.

According to the third embodiment, as in the first and second embodiments, the liquid crystal light valve can provide a high contrast image and reduce the size of the entire apparatus.

The alignment of the LED unit 62 with respect to the optical waveguide 63 is implemented by photolithography technique. Simple and precise position alignment is possible.

In the third embodiment, the substrate 61 serves as a light shielding layer for visible light. Therefore, unlike the first and second embodiments requiring the metal films 15 and 45, it is not necessary to arrange the metal film.

Next, the liquid crystal light valve according to the fourth embodiment of the present invention will be described.

7 is a sectional view schematically showing the liquid crystal light valve of the fourth embodiment. As shown, the liquid crystal light valve 80 includes an optical waveguide 81, a pair of glass substrates 82a and 82b, a transparent electrode 83, a cladding layer 84, a metal film 85, and a photoconductor layer. 86, dielectric mirror 87, data transfer electrode 89, alignment films 90a and 90b, and liquid crystal layer 91.

The optical waveguide 81 is a polymer waveguide made of photopolymerized polycarbonate (Z). The stripe pattern of the optical waveguide 81 may be formed by a photolithography process. Other materials of the polymer waveguide may include polyurethane, epoxy, photosensitive plastic, photoresist, and the like.

Between the optical waveguide 81 and the dielectric mirror 87, a cladding layer 84 is provided to prevent light from leaking from the optical waveguide 81 to the dielectric mirror 87.

The cladding layer 84 is formed by coating a resin having a smaller refractive index than the optical waveguide 81.

Glass substrates 82a and 82b, transparent electrode 83, metal film 85, photoconductor layer 86, dielectric mirror 87, data transfer electrode 89, alignment films 90a and 90b, and liquid crystal layer 91 has the same composites and materials as those included in the first embodiment or the second embodiment.

Like the liquid crystal light valve according to the first or second embodiment, other liquid crystal light valves in the fourth embodiment can also provide a high contrast image and reduce the size of the overall apparatus.

In the above first and second embodiments of the present invention, since the process temperature of the photoconductor layers 16 and 46 (a-SiC: about 300 DEG C when using H) needs to be taken into consideration, the optical waveguide 11 (41) is used an ion exchange glass waveguide having high heat resistance. The photoconductor layers 16 and 46 are deposited on the optical waveguides 11 and 41. On the other hand, in the liquid crystal light valve of the fourth embodiment, the photoconductor layer 86 is located closer to the glass substrate 82a than the optical waveguide 81. Therefore, even the optical waveguide 81 having low heat resistance like the polymer waveguide can be formed after the photoconductor layer 86 is formed. This means that the polymer waveguide with weak heat resistance can be used as the optical waveguide 81.

In the liquid crystal light valve in the first to fourth embodiments, a pair of polarizing plates are formed on both sides of the liquid crystal light valve in a cross-nicol manner. If a ferroelectric liquid crystal having a storage function is used for the liquid crystal light valve, this liquid crystal light valve can also be used as a two-dimensional computing element.

Next, the liquid crystal light valve according to the fifth embodiment of the present invention will be described.

In this embodiment, an EL element is used instead of the optical waveguide serving as a scanning optical signal source.

8 is a perspective view schematically showing a liquid crystal light valve according to a fifth embodiment. FIG. 9 is a cross-sectional view showing the light valve cut along the line A-A shown in FIG.

8 shows a structure in which the phosphor layer is composed of a thin film and the AC power source drives the EL element.

As shown in FIGS. 8 and 9, the liquid crystal light valve 100 includes an organic substrate 101 and 113, a back electrode 102, a lower insulating layer 103, a phosphorescent layer 104, and an upper insulating layer 105. ), Transparent electrode 106, photoconductor layer 107, light shielding layer 108, dielectric mirror 109, alignment layers 110a and 110b, liquid crystal layer 11, electrode for data transmission 112, sealing material ( 111 and a metal film 115.

Next, the manufacturing method of the liquid crystal light valve 100 is demonstrated.

The liquid crystal light valve 100 of this embodiment is formed to have a sandwich structure in which a phosphorescent layer is inserted between insulating layers so that light emitted from the EL element is stably emitted.

First, the back electrode 102 is formed on the glass substrate 101 by EB deposition. The material uses aluminum. Subsequently, the back electrode 102 is patterned in the form of a stripe by etching. Instead of aluminum, Ti (titanium), Mo, or the like may be used.

In the present embodiment, the back electrode 102 is formed in a stripe shape. The shape of the back electrode 102 may be changed to enable various designs of the arrangement of the light emitting device.

Next, an insulating layer for applying a stable high electric field to the phosphor layer 104 is provided between the back electrode 102 and the transparent electrode 106. In fact, these insulating layers are the lower insulating layer 103 formed on the back electrode 102 and the upper insulating layer 105 formed on the transparent electrode 106.

The lower insulating layer 103 is formed to have a laminated structure consisting of Al ₁ O ₃ and SiN _X. An Al ₂ O ₃ film is formed in an Ar (argon) gas environment using an Al ₂ O _{3 target} . SiN _X films are formed in a mixed gas environment of Ar and N ₂ (nitrogen) using Si targets. To form these films, RF (high frequency) sputtering techniques are used.

Subsequently, a phosphorescent layer 104 is stacked below the lower insulating layer 103. The phosphor layer 104 is formed of a thin phosphor layer or a powder phosphor layer obtained by dispersing a phosphor material in dielectricosis.

Now, the thin film phosphorescent layer will be described.

The thin-film artificial layer consists of ZnS: Mn formed by adding 0.5 wt% of Mn (manganese), which is a main phosphor, to ZnS (zinc sulfide), which is a main material. The substrate temperature is set in the range of 300 to 500 ° C. and EB deposition is used. As a result, the light emission wavelength is 585 nm which is yellowish.

Taking into account the dependence of the photoconductor layer 107 formed thereafter on the light sensing wavelength of the phosphorescent layer, the phosphor layer is composed of Ca (calcium sulfide) in the main material with respect to the red region, and Eu (Europium) in the emission center material. CaS: Eu added with ZnS: Tb (terbium) in ZnS for green region and F (fluorine) in charge replenishment material; SrS: Ce, K added cerium) and K (potassium) are used.

In order to form a phosphorescent layer, CVD method, RF sputtering method, ALE (Atomic Layer Epitaxial) method, etc. can be used.

In order to remove the moisture etc. which cause deterioration of a phosphorescent layer, the phosphorescent layer should be vacuum-heat-treated at 400-600 degreeC.

Next, the powdered phosphorescent layer will be described.

The powdered phosphorescent layer is formed of ZnS: Cu and Cl in which Cu (copper) and Cl (chlorine), which are phosphorescent core materials, are added to ZnS in the raw material of the phosphorescent layer material. A fluorescent material such as ZnS: Cu or Cl having a particle diameter of 5 to 20 mu m is dispersed in the dielectric so as to form a phosphorescent layer layer with a thickness of about 50 to 100 mu m.

In the case of the powdered phosphorescent layer, the electric field strength applied to the phosphorescent layer is about 1 × 10 ⁴ to 3 × 10 ⁴ V / cm. Since an insulating breakdown hardly occurs in the phosphor layer, the phosphor layer 104 made of a powdered phosphor layer can be directly inserted between the transparent electrode 106 and the back electrode 102. That is, in this case, the lower insulating layer 103 and the upper insulating layer 105 do not necessarily need to be formed.

The luminescent color obtained by the phosphorescent layer is cyan in the case where the phosphorescent core material is ZnS: Cu, Cl, green in the case of ZnS: Cu, Al, and yellow in the case of ZnS: Cu, Mn, Cl. As in the case of the thin-film phosphorescent layer, a material can be selected according to the dependence on the photosensitive wavelength of the photoconductor layer 107.

The upper insulating layer 105 is formed on the thin film type phosphor layer or the powder type phosphor layer formed in the above-described process.

The upper insulating layer 105 is formed to have a laminated structure consisting of SiO _x and SiN _X. The SiO _X film is formed in a mixed gas of Ar and O ₂ furnace (oxygen) and the SiN _X film is formed in a mixed gas of Ar and N ₂ . In order to form these films, RF sputtering is used.

As the material of the upper insulating layer 105, BaTa ₂ O ₆ (barium tantalate), SrTiO ₃ (strontium titanate) or Ta ₂ O ₅ (tantalum oxide) may be used instead of SiO _X and SiN _X.

Thereafter, using the RF sputtering method, the transparent electrode 106 is almost entirely on the substrate formed of the glass substrate 101, the back electrode 102, the lower insulating layer 103, the phosphorescent layer 104 and the upper insulating layer 105. ). ITO is used as a material of this transparent electrode 106.

The above-described structure has the advantage that the liquid crystal light valve can be driven completely independently of the scanning optical signal source composed of the phosphor layer 104.

The phosphor layer 104 made of the EL element is driven by a bipolar pulse. In order to use a unipolar pulse, it is necessary to arrange a current limiting layer between the phosphor layer 104 and the back electrode 102. This current limiting layer is a thick film formed by dispersing MnO ₂ (manganese dioxide) in a binder resin, and its thickness is 1 to 10 mu m.

Subsequently, an a-Si: H film is formed on the transparent electrode 106 by plasma CVD. This film serves to receive light from the phosphor layer 104 serving as an optical source for scanning.

As the photoconductor layer 107 whose impedance changes depending on the irradiation amount of light, Bi ₁₂ SiO ₂₀ , CdS, a-SiC: H, a-SiO: H a-SiN: H can be used.

Next, the dielectric mirror 109 is formed on the photoconductor layer 107 through the light shielding layer 108 by the EB deposition method. The dielectric layer 109 is a multilayer film in which a TiO ₂ film and an SiO ₂ film are alternately stacked.

To prevent leakage of the read light 106 through the dielectric mirror 109 to the photoconductor layer 107, a light shielding layer 108 is formed between the dielectric mirror 109 and the photoconductor layer 107.

The light shielding layer 108 may be Al ₂ O ₃ in which a carbon dispersed organic thin film, CdTe, or Ag is plated without an electric field applied thereto.

On the back surface of the glass substrate 101, that is, the surface opposite to the surface on which the EL element is formed, a metal film 115 for blocking light emitted from light sources other than the EL element is disposed. This metal film 115 is formed of Ag, Al or Mo. Moreover, the pigment-disperse light shielding film used for the color filter of a liquid crystal panel, etc. can also be used instead of the metal foil 115.

On the glass substrate 113 facing the glass substrate 101, an electrode 112 for data transfer is formed. To form this electrode 112, the ITO material is patterned into the next stripe form by sputtering.

The dielectric mirror 119 and the data transfer electrode 112 are spin coated with a polyimide film and then sintered to form alignment films 110a and 110b, respectively. Surfaces of the alignment films 110a and 110b are subjected to molecular alignment treatment by polishing.

Subsequently, the glass substrates 101 and 113 are pasted with spacers (not shown) therebetween so that the dielectric mirror 109 and the phosphor layer 104 serving as a scanning optical signal source are at right angles. Then, liquid crystal is injected into the space between the glass substrates for the purpose of forming the liquid crystal layer 111 and sealed with a sealing material 114.

The impedance of the liquid crystal of the liquid crystal layer 111 is much larger than the impedance of the portion of the photoconductor layer 107 selected as the scanning line, but smaller than the impedance of the portion of the photoconductor layer 107 not selected as the scanning line. Therefore, almost all data signals applied between the electrodes are applied to the liquid crystal layer 111. On the other hand, since it has a larger impedance than the portion of the photoconductor layer 209 not selected as the scan line, no data signal is applied to the liquid crystal layer 111.

FIG. 10 is a view schematically illustrating a driving unit included in the liquid crystal light valve 100 according to the fifteenth embodiment. For simplicity, the signal and timing generator are not shown.

As shown, the driving unit of the liquid crystal light valve 100 drives the driver array 121 for driving the EL element for the frequency signal and the driving circuit 122 for driving the data transfer electrode 112 included in the liquid crystal light valve 100. ) Provides.

The configuration of the projection display device using the liquid crystal light valve 100 and the operation mode of the liquid crystal layer are the same as those of the projection display device shown in FIG.

Therefore, when the liquid crystal light valve according to the fifth embodiment is used, a high contrast image can be formed similarly to the liquid crystal light valve according to the first embodiment, and the device can be miniaturized.

In addition, it is not necessary to connect an array of light emitting elements such as an LED array to a liquid crystal light valve, and thus does not require high technology such as alignment.

Next, the liquid crystal light valve according to the sixth embodiment of the present invention will be described.

11 is a schematic cross-sectional view of a liquid crystal light valve according to a sixth embodiment.

As shown, the liquid crystal light valve 200 includes the optical waveguides 201 and 202, the first substrate 203, the second substrate 204, the cladding layer 205, the transparent electrode 206, the adhesive resin 207, Metal film 208, photoconductor layer 209, light shielding film 210, dielectric mirror 211, glass substrate 212, data transfer electrode 213, alignment films 214a and 214b and liquid crystal layer 215 It is configured to have.

As the scanning optical signal, leaky light can be used through the optical waveguides 201 and 202.

First, the manufacturing method of the optical waveguides 201 and 202 will be described.

In order to form the optical waveguide 201, grooves are formed on the first substrate 203 by a wet etching method. More specifically, the resist is coated on both sides of the first substrate 203 and pre-sintered. The films are exposed, developed and post-sintered. A mask is formed on one side to form these grooves. Subsequently, after etching with buffered hydrofluoric acid, the resist is peeled off from both sides. As a result, stripe-shaped grooves are formed on the side surfaces.

In addition to the wet etching method, the grooves may be formed by dry etching methods such as sputter etching using Ar gas and Ar-ion etching, or by mechanical polishing.

As the material of the photoconductor layer 201, a polymer material which is easily processed or molded by photolithography technology is used. Specifically, polyimide having excellent heat resistance is most preferable because it is necessary to raise the temperature of the substrate to 300 ° C when forming the photoconductor layer 209 by the plasma CVD method.

On the grooved surface of the first substrate 203, polyimide is diluted in a solvent and coated with a spinner. This surface is then heat treated. A resist is applied to the heat treated surface. The resist coated surface is presintered, exposed, developed and post sintered to form a mask to cover the grooves formed in the first substrate 203. The applied polyimide is then etched and the resist is peeled off at its surface. Finally, heat treatment is performed to form the optical waveguide 201 on the surface.

As an etching method of a polyimide, it uses by the etching method by hydrazine and a hydrate-type corrosion liquid.

The polyimide used in this example is non-photosensitive. However, the use of photosensitive polyimide can reduce the optical waveguide fabrication process steps.

Since the polyimide has a larger refractive index than the first substrate 203 made of a fibreboard (see below), no cladding layer is required on the substrate side.

On the other hand, the transparent electrode 206 made of ITO is formed on the optical waveguide 201. Since the transparent electrode 206 has a larger refractive index than the optical waveguide 201, the transparent electrode 206 should have a cladding layer 205. The cladding layer 205 forms SiO ₂ , that is, a dielectric having a low refractive index by sputtering.

Another method of forming the clad layer 205 uses a polyimide having a lower refractive index than the polyimide used to form the optical waveguide 201. In this case, the cladding layer 205 must be formed so that an intermediate amount of light leaks from the optical waveguide 201. Suitable thickness of clad layer 205 is 50 to 5000 mm 3. In this embodiment, the thickness of the cladding layer 205 is about 3000 mm 3.

When the optical waveguide 202 is formed on the second substrate 204, the refractive indices of the first substrate 203, the second substrate 204, the optical waveguide 202, and the adhesive resin 207 need to match. That is, in order for the light leaked from the optical waveguide 202 to pass through the first substrate 203, the first substrate 203 must have a refractive index equal to or greater than that of the optical waveguide 202. Furthermore, the second substrate 204 should have a smaller refractive index than the optical waveguide 202.

To satisfy this condition, a fibrous plate having a refractive index of about 1.53 for the first substrate 203, quartz having a refractive index of about 1.457 for the second substrate 204, and about 1.53 for the optical waveguide 202. A polyimide having a refractive index should be selected. Since the adhesive resin 207 comes into contact with the cladding layer of the optical waveguide 202, it should be selected to have a refractive index of about 1.48. In this case, polyimide having a refractive index of about 1.61 can be used for the optical waveguide 201.

The optical waveguide 201 has the same width as the optical waveguide 202. The pitch between the optical waveguides 202 adjacent to each other is twice as wide as the width of each of the optical waveguides 201. Like the optical waveguide 201, the pitch between adjacent optical waveguides 202 is twice as wide as each of the optical waveguides 202. The optical waveguides 201 are positioned to be shifted by 1/2 pitch in parallel from the corresponding optical waveguides 202, respectively.

In order to form grooves on the second substrate 204 made of quartz, it is very effective to use a reactive ion etching (RIE) method. Instead of CF ₄ as reactant gas, mixed gas of CF ₄ and H ₂ , mixed gas of CF ₄ and C ₂ H ₄ , mixed gas of C ₂ F ₅ , C ₂ F ₆ and C ₂ H ₄ , CHF ₃ and C ₄ F ₈ can be used. It is also possible to use a sputtering etching method using argon gas, an argon ion beam etching method or a mechanical polishing method.

The method of forming the optical waveguide 202 is the same as the method of forming the optical waveguide 201 described above.

On the back surface of the second substrate 204, that is, on the surface opposite to the surface where the optical waveguide 202 is formed, a metal film 208 is formed to block all light applied anywhere except the optical waveguide.

The metal film 208 may be made of Ag, Al or Mo. Otherwise, a pigment-dispersion light shielding film mainly used as a color filter of the liquid crystal panel may be used instead of the metal film 208.

Next, a method of forming a collision located on the clad layer 205 will be described.

On the cladding layer 205, a transparent electrode 206 made of ITO is formed by sputtering. On the transparent electrode 206, a material of a-Si: H is formed as the photoconductor layer 209 by the plasma CVD technique. The photoconductor layer receives light from the optical waveguide 201.

Bi ₁₂ SiO ₂₀ , CdS, a-SiC: H, a-SiO: H, or a-SiN: H may be used as the photoconductor layer 209 whose impedance changes according to the irradiation amount of light.

Next, a light shielding layer 210 is formed on the photoconductor layer 209. Thereafter, the dielectric mirror 211 is formed by EB deposition. The dielectric mirror 211 is a multilayer film in which TiO ₂ layers and SiO ₂ layers are alternately stacked.

In order to prevent the read layer 216 from leaking into the photoconductor layer 209 through the dielectric mirror 211, a light shielding layer 210 must be formed between the dielectric mirror 211 and the photoconductor layer 209. As the light blocking layer 210, Al ₂ O ₃ electroplated with a carbon-dispersed organic thin film, CdTe, and Ag may be used.

The data transfer electrode 213 is provided on the glass substrate 212 facing the first substrate 203. Transparent ITO deposited by sputtering to form the data transfer electrode 213 is patterned in a stripe shape on the glass substrate 212.

On the dielectric mirror 211 and the data transfer electrode 213, the alignment films 214a and 214b are formed by spin coating polyimide and sintering the coated film. Molecular alignment treatment is performed on the surfaces of the alignment films 214a and 214b.

Then, the first substrate 203 and the glass substrate 212 are attached to each other through spacer (s) (not shown) such that the data transfer electrode 213 crosses the optical waveguide 201 at right angles. . Liquid crystal is injected into the space between both substrates and sealed to form the liquid crystal layer 215.

Finally, the first substrate 203 on which the optical waveguide 201 is formed is disposed at an appropriate position with respect to the second substrate 204 on which the optical waveguide 202 is formed, and both substrates 203 and 204 are attached to the adhesive 207. Glue them together. As described above, the first substrate 203 is made of fibrous board and the second substrate 204 is made of quartz.

The liquid crystal used to form the liquid crystal layer 215 has a larger impedance than the portion of the photoconductor layer 209 selected as the scanning line by the irradiation light, and has a smaller impedance than the portion of the photoconductor layer 209 not selected as the scanning line. Has

The liquid crystal of the liquid crystal layer 215 has a much higher impedance than the portion of the photoconductor layer 209 selected as the scan line. Therefore, most of the data signal applied between the electrodes is applied to the liquid crystal layer 215. However, since the liquid crystal layer 215 has a larger impedance than the portion of the photoconductor layer 209 which is not selected as the scan line, no other data signal is applied on the liquid crystal layer 215.

Like the liquid crystal light valve according to the first embodiment, the liquid crystal light valve according to the sixth embodiment can also provide a high contrast image and realize miniaturization of the device.

In known liquid crystal light valves, an optical waveguide is formed on one substrate. Thus, there is a gap between adjacent scan lines. However, according to this embodiment, since the optical waveguide is formed on the two substrates, such a gap between adjacent scan lines is eliminated. Therefore, the number of scanning lines can be increased, thereby improving the numerical aperture and resolution of the liquid crystal light valve.

When the first substrate 203 is made of glass, the optical signal leaked from the optical waveguide 202 is diffused while passing through the first substrate 203. Thus, the amount of light on the scan line is reduced. In addition, crosstalk may occur when an optical signal leaks over adjacent scanning lines. In order to prevent this disadvantage, in the liquid crystal light valve of the sixth embodiment, the first substrate 203 is made of a fiber board. The fiber board can transmit the optical signal induced in the optical waveguide 202 in the vertical upward direction (opposite to the traveling method of the read light shown in FIG. 11) without spreading the optical signal in the horizontal direction.

FIG. 12 schematically shows a drive unit of the liquid crystal light valve 200 shown in FIG.

As shown in the figure, the drive unit provides a drive circuit 222 for driving the scan signal LED array 211 and the data transfer electrode 213. A semiconductor laser array may be used instead of the LED array 221.

The LED array 221 is connected to the liquid crystal light valve 200 so that a light pulse signal can be guided from the LED array 221 to the liquid crystal light valve 200.

FIG. 13 is a perspective view showing in detail the connection of the LED array 221 shown in FIG.

As shown in the figure, the LED array 221 shown in FIG. 12 is composed of LED arrays 221a and 221b. Light emitted from the LED arrays 221a and 221b is guided to the optical waveguides 225a and 225b through the optical prisms 223a and 223b, respectively. The optical waveguides 225a and 225b respectively correspond to the optical waveguides 201 and 202 of the liquid crystal light valve shown in FIG.

That is, each pair of LED array and optical prism is provided to the upper and lower optical waveguides, respectively. For simplicity of explanation, only the upper and lower optical waveguides 225a and 225b are shown in FIG. 13, and other elements of the liquid crystal light valve are not shown.

Instead of using the optical prisms 223a and 223b, the respective cross sections of the optical waveguides 225a and 225b are directly connected to the respective light emitting surfaces of the LED arrays 221a and 221b.

Reference numerals 224a and 224b indicate reflectors reflecting light on cross sections of the optical waveguides 225a and 225b in order to guide light efficiently into the photoconductor layer of the liquid crystal light valve 200. These reflectors are made of Al or Ag.

The configuration of the projection image display apparatus using the liquid crystal light valve 200 and the operation method of the liquid crystal layer are the same as those of the projection image display apparatus shown in FIG.

Now, a liquid crystal light valve according to a seventh embodiment of the present invention will be described.

14 is a cross-sectional view schematically showing a liquid crystal light valve according to a seventh embodiment of the present invention.

In such a liquid crystal light valve, a phosphor layer made of an EL element is used instead of the lower optical waveguide 202 serving as a scanning optical signal source included in the liquid crystal light valve 200 shown in FIG.

As shown in FIG. 14, the liquid crystal light valve 300 is formed of a fiber plate 301, an optical waveguide 302, a back electrode 303, a glass substrate 304, a lower insulating layer 305, and an phosphorescent element. Layer 306, upper insulating layer 307, transparent electrode 308, adhesive resin 309, cladding layer 310, transparent electrode 311, metal film 312, photoconductive layer 313, light shielding The layer 314, the dielectric mirror 315, the glass substrate 316, the data transfer electrode 317, the alignment films 318a and 318b, and the liquid crystal layer 319 are aligned.

Now, a method of manufacturing the liquid crystal light valve 300 will be described.

The liquid crystal light valve 300 is formed in a sandwich structure in which the phosphor layer 306 is disposed between the upper and lower insulating layers 305 and 307 so that the EL element can stably output light.

First, the back electrode 303 is formed on the glass substrate 304. In this process, Ti or Mo may be used instead of Al by using the EB deposition method.

Insulation layers are required between the back electrode 303 and the transparent electrode 308 for applying a stable high field to the phosphor layer 306. Specifically, the lower insulating layer 305 is formed on the back electrode 303 side, and the upper insulating layer 307 is formed on the transparent electrode 308 side.

The lower insulating layer 305 uses a laminated structure in which an Al ₂ O ₃ layer and a SiN _X layer are alternately stacked. A layer of Al ₂ O ₃ is a layer formed in an Ar environment having an Al ₂ O ₃ target with SiN _X is formed in a mixed gas of Ar and N ₂ with a Si target. At this time, the RF sputtering method is used.

Then, a phosphorescent layer made of an EL element is laminated on the lower insulating layer 305. The phosphor layer 306 is formed of a powder phosphor layer and a thin film phosphor layer in which fluorescent material is dispersed in a dielectric. An upper insulating layer 307 is then formed over the phosphor layer 306.

The upper insulating layer 307 is formed to have a laminated structure in which a SiO _X layer and a SiN _X layer are alternately stacked. The layer of SiO _X is formed in a mixed gas of Ar and O ₂ having a Si target, and the layer of SiN _X is formed in a mixed gas of Ar and N ₂ having a Si target. At this time, the RF sputtering method is used.

Instead of SiO _X and SiN _X , the materials that can be used to form the upper insulating layer 307 are BaTa ₂ O ₆ , SrTiO ₆ or Ta ₂ O ₅ .

Then, the transparent electrode 308 is formed on the upper insulating layer 307 using the RF sputtering method. The material of the electrode 308 is ITO.

The above arrangement has the advantage that the light valve can be driven completely independently of the light emitting layer 306 serving as the scanning optical signal source when the transparent electrode 308 is grounded.

The phosphor layer 306 made of an EL element is AC driven by a bipolar pulse. If a current limiting layer is provided between the phosphor layer 306 and the back electrode 303, the phosphor layer 306 can be driven directly by a unipolar pulse. The current limiting layer is a thick film formed of an adhesive resin in which MnO ₂ is dispersed. The thickness of this film is 1 µm to 10 µm.

Next, the manufacturing method of the optical waveguide 302 is demonstrated.

In order to form the optical waveguide 302, grooves for optical waveguide are formed on the fiber plate 301 by wet-etching. That is, the fibreboard 301 coats the resist on both surfaces. Pre-sintering, exposure, development and post-sintering are performed to form a mask on one surface of the coated resist. Subsequently, etching is performed on the mask by using buffered hydrofluoric acid and the resist is peeled off from the surface to complete the stripe groove on the surface.

Instead of wet-etching techniques, dry etching or mechanical polishing may be used to form grooves, such as sputter etching using Ar gas or argon ion beam etching.

The optical waveguide 302 uses a polymer material that is easy to photolithography or molding. Specifically, when the photoconductor layer 313 is formed by the plasma CVD technique, since the substrate must be heated to 300 ° C, polyimide having high heat resistance is most suitable.

The polyimide is diluted with a solvent and coated with a spinner on the grooved surface of the first substrate 301. Then, this surface is heat treated. The resist is coated on the heat treated side. The surface coated with the resist is pre-sintered, exposed, developed and post-sintered to form a mask to cover the grooves formed in the first substrate 301. The coated polyimide is then etched and the resist is peeled off at its surface. Finally, the heat treatment is performed to form the optical waveguide 302 on the surface.

As the etching method of the polyimide, a wet etching method using hydrazine and a hydrate-based corrosion solution is used.

In this example, the polyimide used is non-photosensitive. However, the use of photosensitive polyimide can reduce the steps of the optical waveguide manufacturing method.

Since the transparent electrode 311 formed on the optical waveguide 301 and composed of ITO has a larger refractive index than the optical waveguide 302, it is necessary to form the cladding layer 310. By the bias sputtering method, the clad layer 310 is made of SiO ₂ , which is a dielectric having a low refractive index.

As another method of forming the cladding layer 310, the polyimide for producing the cladding layer 310 has a smaller refractive index than the polyimide used for producing the optical waveguide 302. In this case, the clad layer 310 must be formed so that an appropriate amount of light leaks from the optical waveguide 302. The appropriate thickness of the clad layer 310 is 50 mm 3. In this embodiment, the thickness of the clad layer 310 is about 3000 mm 3.

The optical waveguide 302 has the same width as the back electrode 303. The pitch between adjacent optical waveguides 302 is twice the width of the optical waveguide 302. Like the optical waveguide 202, the pitch between adjacent back electrodes 303 is twice the width of the back electrodes 303. The optical waveguides 302 are positioned parallel to the back electrode 303 so as to shift from the corresponding back electrode 303 by about a half pitch.

A metal film 312 is formed on the back surface of the second substrate 304, that is, on the surface opposite to the surface on which the back electrode 303 is formed, to block the light applied at a place other than the optical waveguide.

The metal film 312 may be formed of Ag, Al, or Mo. Instead of the metal film 312, a pigment-dispersion light shielding film mainly used as a color filter of a liquid crystal panel can be used.

Next, a method of manufacturing a layer located on the clad layer 310 will be described.

On the cladding layer 310, a transparent electrode 311 made of ITO is deposited by sputtering. On the transparent electrode 311, an a-Si: H material is used by the plasma CVD method as the photoconductor layer 313 where light is received from the optical waveguide 301 and the EL element.

Bi ₁₂ SiO ₂₀ , CdS, a-SiC: H, a-SiO: H, or a-SiN: H may be used as the photoconductor layer 313 whose impedance changes according to the irradiated light.

Next, the light shielding layer 314 is formed on the photoconductor layer 13. Subsequently, dielectric mirror 315 is formed by EB deposition. The dielectric mirror 315 is composed of a multilayer film formed by alternately stacking TiO ₂ layers and SiO ₂ layers.

In order to prevent the read light 320 from leaking through the dielectric mirror 315 to the photoconductor layer 313, a light shielding layer 314 must be provided between the dielectric mirror 315 and the photoconductor layer 313. . As the light shielding layer 314, Al ₂ O _{3 obtained} by plating a carbon-dispersed organic thin film, CdTe, and Ag with no electric field applied thereto can be used.

On the glass substrate 316 facing the fiber board 301, an electrode 317 for data transmission is provided. The transparent ITO deposited on the glass substrate 316 by the sputtering method to form the electrode 317 is patterned in a stripe form.

On the dielectric mirror 315 and the data transfer electrode 317, back films 318a and 318b are formed by spin coating polyimide and sintering the coated film, respectively. Subsequently, molecular alignment is performed on the surfaces of the alignment films 318a and 318b.

After the alignment films 318a and 318b are formed, the fiber plate 301 and the glass substrate 316 through spacer (s) (not shown) so that the data transmission electrode 317 crosses the optical waveguide 302 at right angles. Glue them together. The liquid crystal is injected into the space between the two substrates and then sealed to form the liquid crystal layer 319.

Finally, the fibrous plate 301 on which the optical waveguide 302 is formed is properly aligned with respect to the glass substrate 304 on which the phosphor layer 306 is formed. Further, the adhesive resin 309 is used to bond the 301 and 304 to each other.

The liquid crystal used to generate the liquid crystal layer 319 has a larger impedance than the portion of the photoconductor layer 313 selected as the scanning line by the irradiation light and is smaller than the portion of the photoconductor layer 313 not selected as the scanning line. Has impedance. Therefore, most of the data signals applied between the electrodes are applied to the liquid crystal layer 319. However, since the portion of the photoconductor layer 313 which is not selected as the scan line has a larger impedance than the liquid crystal layer 319, the data signal is not applied to the liquid crystal layer 319.

Like the liquid crystal light valve according to the first embodiment, the liquid crystal light valve according to the sixth embodiment can be provided with a high contrast image and the size of the device can be miniaturized.

In a known liquid crystal light valve, an optical waveguide is formed on a substrate. Thus, there is a gap between adjacent scan lines. However, according to the present embodiment, an optical waveguide is formed on two substrates so that this gap between adjacent scanning lines can be eliminated. This increases the number of scanning lines, improving the resolution and increasing the numerical aperture of the liquid crystal light valve.

If a glass substrate is used instead of the fiber board 301, the light signal leaked from the phosphor layer 306 is diffused while the light passes through the glass substrate. This reduces the amount of light on the scan line. Furthermore, crosstalk can occur when an optical signal leaks onto adjacent scan lines. In order to prevent this disadvantage, in the liquid crystal light valve of the seventh embodiment, the substrate is made of fibreboard 301. By using the fiber board, the optical signal derived from the phosphor layer 306 can be transmitted in the vertical direction (in a direction opposite to the traveling direction of the read light shown in FIG. 14) without being diffused in the horizontal direction with the optical signal.

In the liquid crystal light valve according to the seventh embodiment, the lower optical waveguide serving as the optical signal source for scanning uses the phosphor layer 306 including the EL element. Similarly, as the upper optical waveguide serving as the optical signal source for scanning, a phosphorescent layer composed of EL elements can be used. Alternatively, the upper and lower valve optical waveguides may use phosphorescent layers each composed of EL elements. In any case, the liquid crystal light valve can be properly driven.

In this embodiment, a collision-excitement type EL element in stripe form is used as the scan line. In this case, an injection type EL element can also be used. As an example of the injection type EL element, a pin element having a phosphorescent layer made of a-SiC: H can be used.

The configuration of the projection display device using the liquid crystal light valve 300 and the operation mode of the liquid crystal layer included in the light valve 300 are the same as those of the projection image display device shown in FIG. Accordingly, the liquid crystal light valve 300 may be applied to a projection display device having high contrast and high resolution.

Referring to FIG. 15, a liquid crystal light valve according to an eighth embodiment of the present invention is described. The liquid crystal light valve of the eighth embodiment is arranged so that the liquid crystal light valve according to the first to seventh embodiments can be applied to the two-dimensional optical operation element.

FIG. 15 is a schematic diagram showing a photo-operation method when the liquid crystal light valve according to the eighth embodiment is applied to a two-dimensional photo-operation element.

As shown, the liquid crystal light valve 471 has the first to seventh embodiments (FIGS. 1, 5, 7, and 9 except for the metal films 15, 45, 85, 115, 208 and 312). 11 and 14), the same components as in the liquid crystal light valves 10 to 300 are arranged. 474 denotes a polarizing plate provided on either surface of the light valve 471 in a cross-nicol manner.

The liquid crystal light valve 471 uses a ferroelectric liquid crystal having a storage function as the liquid crystal layer. In this case, a guest-host type or a phase-change type liquid crystal may be used as the storage liquid crystal.

Similar to the other liquid crystal light valves 10, 40, 80, 100, 200, and 300 in the first to seventh embodiments, the liquid crystal light valve 474 may provide a high contrast image.

Next, when the liquid crystal light valve 471 is used as the two-dimensional optical operation element, the optical operation method will be described.

First, part of the two-dimensional data is recorded on the light valve 471 as an LED scan signal and a data signal. FIG. 15 shows a state where image data-472 is recorded in the light valve 471. FIG. That is, the recorded image data-472 is stored in the liquid crystal layer because the light valve 471 provides the storage liquid crystal as described above.

Next, when another kind of image data + (473) is applied to the light valve 471 from one side (shown to the left of FIG. 15) in infrared, a photoconductor layer composed of a-Si: H transmits infrared rays. Because of its nature, infrared light representing data + 473 can be transmitted through the photoconductor layer at light valve 471. Transmitted light ray 475 is blocked by polarizer 474 at the portion of the liquid crystal where data-472 is stored. Thus, transmitted beam 475 is selected such that data-472 is not affected from data + 473. In this way, the liquid crystal light valve 471 of the eighth embodiment can be applied to two-dimensional photo-operation or image checking.

Claims (14)

First substrates 12a, 42, 82a, 101, 203, 301 having first transparent electrode means 13, 43, 83, 106, 206, 308, 311 thereon; Second substrates 12b, 42b, 82b, 113, 212, 316 having second transparent electrode means thereon; A liquid crystal layer 21, 51, 91, 111, 215, 319 provided between the first substrate and the second substrate; A photoconductor layer (16,46,86,107,209,313) adapted to change impedance in response to incident light thereon, the photoconductor layer comprising: a photoconductor layer disposed between the liquid crystal layer and the first substrate; A liquid crystal light valve for forming an image in response to a data signal disposed on the same surface as the first substrate of the liquid crystal layer and including a plurality of light waveguides extending in a first direction. The second transparent electrode means includes a plurality of stripe electrodes extending along a direction crossing the first direction, and an optical scan signal supply means is connected to the optical waveguide to emit light to the photoconductor layer when in use. And a data signal supply means is connected to said second electrode to apply a data signal to said second electrode when in use. The liquid crystal light valve of claim 1, wherein the plurality of optical waveguides are formed on the first substrate, and the first transparent electrode means is patterned in a stripe shape. 3. The liquid crystal light valve of claim 2, wherein the first transparent electrode means includes a plurality of stripe electrodes extending in parallel with the optical waveguide. The liquid crystal light valve of claim 1, wherein each of the optical waveguides is formed of a polymer optical waveguide, and the photoconductor layer is positioned between the first substrate and the plurality of optical waveguides. 2. The optical waveguide of claim 1, wherein each of the optical waveguides comprises an electroluminescent element including a phosphorescent layer and two insulating layers sandwiching the phosphorescent layer and a rear electrode therebetween. Liquid crystal light valve. The optical waveguide according to claim 1, wherein the light valve further comprises third substrates 204 and 304 disposed on the first substrates 202 and 301 at opposite sides with respect to the first projection electrode means 206 and 311. Is divided into two groups each formed on the first and third substrates. The liquid crystal light valve of claim 6, wherein the first substrate is formed of a fiber plate. 7. The liquid crystal light valve according to claim 6, wherein at least one group of optical waveguides is composed of an electroluminescent element. 2. The liquid crystal light valve as claimed in claim 1, wherein the optical scanning signal supply means includes a light emitting diode array disposed at one end of the optical waveguide so as to induce a scanning optical signal into the optical waveguide. 2. The liquid crystal light valve according to claim 1, wherein said optical scanning signal supply means includes a semiconductor laser disposed at one end of said optical waveguide so as to guide an optical signal for scanning to said optical waveguide. The liquid crystal light valve according to claim 1, wherein the optical waveguide includes an electroluminescent element, and the optical scanning signal supply means includes a driver array for driving the electroluminescent element. The liquid crystal light valve of claim 3, wherein the first electrode is parallel to the plurality of optical waveguides having a stripe shape and positioned to be shifted by a half pitch. 8. The optical waveguide on the first substrate and the optical waveguide on the third substrate are arranged at a pitch that is twice the width of one optical waveguide, and the optical waveguide on the first substrate and the third substrate are respectively arranged. The optical waveguide of the phase is shifted by half pitch with respect to each other. The method of claim 13, wherein the indexes of refraction of the first substrate, the third substrate and the optical waveguide are the same, and the refractive index of the first substrate is the same as the refractive index of the optical waveguide of the third substrate. Liquid crystal light valve, characterized in that or large.