JPH0511269A - Optical modulating element and display device - Google Patents

Abstract

PURPOSE:To obtain the optical modulating element which can display a high- resolution image by cooling the optical modulating element which is heated with high-output incident light by a cooling mechanism. CONSTITUTION:A flow passage for passing a cooling medium to at least one substrate of the optical modulating element constituted by laminating at least transparent electrodes Et1 and Et2, a photoconductive layer member PCL, and an optical modulating material layer member PML between two opposite arranged substrates BP1 and BP2 is provided and the cooling medium is passed through this flow passage to cool the element which is heated with the high- output incident light, thereby displaying the high-resolution image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light modulation element suitable for an optical computer, an image pickup device and the like and a display device using the light modulation element, and more particularly to improvement of the light modulation element.

[0002]

2. Description of the Related Art As a key device for an optical computer or a large screen display, an optical modulator SLM as shown in FIG. 7 has been developed. The light modulation element SLM is formed by laminating a transparent substrate BP1, a transparent electrode Et1, a photoconductive layer member PCL, a dielectric mirror DML, a light modulation material layer member PML, a transparent electrode Et2 and a transparent substrate BP2. . The transparent electrodes Et1 and Et2 are composed of a thin film of a transparent conductive material, and the photoconductive layer member PCL is composed of a material exhibiting photoconductivity in the wavelength range of light used, and further, a dielectric material. As the mirror DML, a well-known one configured as a multilayer film is used so as to reflect light in a predetermined wavelength band, and the light modulation material layer member PML is also used.
Is a light modulating material (for example, nematic liquid crystal, lithium niobate, or the like) that changes the state of light (polarization state of light, optical rotation state of light, scattering state of light) according to the applied electric field strength.
BSO, PLZT, polymer-liquid crystal composite film, etc.). E is a power source for applying a predetermined voltage between the transparent electrodes Et1 and Et2. This power source E is shown as an AC power source in the figure, but the configuration of the light modulation material layer member PML in the light modulation section is shown. Depending on the substance, it can be used as a DC power supply or an AC power supply. WL is writing light which is incident from the transparent substrate BP1 side of the light modulation element SLM and is condensed on the photoconductive layer member PCL, and the writing light WL is modulated in light emission amount according to the information to be displayed. It is what

A power source E is placed between the transparent electrodes Et1 and Et2.
From the transparent electrode Et1 side of the light modulation element SLM to which a predetermined voltage is supplied from the light modulation element SLM, the light emission amount is modulated by the information to be displayed, for example, N writing lights WL.
Is incident and is condensed on the photoconductive layer member PCL through the transparent substrate BP1 and the transparent electrode Et1, the photoconductive layer member PCL of the portion where the N writing lights WL are condensed.
The electric resistance value of the light is changed in accordance with the amount of irradiated light, and the amount of light emission is modulated by the information to be displayed at the boundary between the photoconductive layer member PCL and the dielectric mirror DML. N charge images are formed in a state corresponding to the irradiation light amounts of the N write lights WL that are sequentially arranged. The N charge images are the sequential pixel signals in the time series signal. In the state in which the electric charges having the electric charges corresponding to are arranged. Therefore, the electric field due to the N charge images formed at the boundary between the photoconductive layer member PCL and the dielectric mirror DML is applied to the light modulation material layer member PML in the light modulation element SLM.

In such a state, the light modulation element SLM
When the read light RL is incident from the transparent substrate BP2 side in the above, the read light RL is changed from the transparent substrate BP2 to the transparent electrode E.
t2 → light modulation material layer member PML → dielectric mirror DML reaches the dielectric mirror DML and is reflected there, and the reflected light of the read light is dielectric mirror DML → light modulation material layer member PML → transparent electrode Et2 → transparent The light is emitted from the light modulation element SLM along the path of the substrate BP2 →. In this way, for example, N light fluxes emitted from the light modulation element SLM are applied with an electric field of N charge images in a state in which charges having a charge amount corresponding to the sequential pixel signals in the time series signal are arranged. Since it is a light flux that has reciprocated through the light modulation material layer member PML, the N light fluxes have a light state that changes corresponding to the sequential pixel signals in the time series signal.

When the constituent material of the light modulating material layer member PML in the light modulating element SLM is such that (1) the scattering state of light passing therethrough is changed according to the electric field strength applied thereto. In addition, as described above, the reflected light flux of the N pieces of read light emitted from the light modulation element SLM has a state in which the light intensity changes corresponding to the N pieces of sequential pixel information in the time-series signal. In addition, the constituent material of the light modulation material layer member PML in the light modulation element SLM (2) changes the polarization state of the light passing therethrough according to the electric field strength applied thereto. In such a case, the reflected light fluxes of the N pieces of readout light emitted from the light modulation element SLM as described above are polarized corresponding to the N pieces of sequential pixel information in the time-series signal. Those whose state is changing It has become. In the case of the above (2), by passing the light flux emitted from the light modulation element SLM to the analyzer (for example, the beam splitter), the reflected light flux of the N read light emitted from the light modulation element SLM is The light intensity can be changed in correspondence with the information of N sequential pixels in the time-series signal.

As described above, in the light modulation element SLM, when an optical image is written on the photoconductive layer member PCL while a predetermined voltage is applied between the transparent electrodes Et1 and Et2, the light intensity of the image changes. Accordingly, the impedance of the photoconductive layer member PCL changes, and the read light given to the light modulation material layer member PML is modulated.

[0007]

This light modulation element SLM is attracting attention as a device for a large-screen display with high brightness because it can modulate a large reading light with a small writing light. In that case, a high output power can be obtained in a small area. Since light is incident, there is a problem in that the temperature rises due to the light absorption of the constituent members and the operating point moves, or when liquid crystal is used for the light modulation material layer member PML, a phase transition occurs and operation becomes impossible. . Therefore, in order to solve such a problem, the light modulation element SLM
For example, a method of cooling the light modulation element SLM by increasing the thickness of the transparent substrate BP1 provided on the front surface (incident light incident side) of the photoconductive layer member PCL and providing a cooling mechanism there is conceivable. In such a method, the thickness of the entire surface of the device is increased by increasing the thickness of the front surface of the photoconductive layer member PCL, which has a drawback that the resolution is deteriorated. The same drawback is caused by the light modulation material layer member PML.
On the side, the thickness of the transparent substrate BP2 on the incident side of the reading light is increased and a cooling mechanism is provided there. FIG. 8 is a characteristic curve diagram showing changes in spatial frequency and resolution when a member having a refractive index different from that of air is arranged in front of the projection target image in the light modulation element. It can be seen that if there is any inclusion on the front surface of the projection target image, the resolution deteriorates as the thickness increases.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and as a first invention, at least a transparent electrode and a light modulating material layer member are provided between two substrates which are arranged relative to each other. In the laminated optical modulation element, at least the one substrate is provided with a flow path for allowing a refrigerant to pass therethrough, and as a second invention, at least between the two relatively arranged substrates. In a light modulation element formed by laminating a transparent electrode, a photoconductive layer member, and a light modulation material layer member, a light modulation element in which a flow path for passing a coolant is provided in at least the one substrate is further provided. As an invention, a flow of a refrigerant is allowed to pass through at least one substrate of an optical modulation element formed by laminating at least a transparent electrode, a photoconductive layer member, and a light modulation material layer member between two substrates that are arranged relative to each other. Optical modulator with a channel And a writing means for writing desired display information in the light modulation element, a reading means for reading the display information written in the light modulation element, and a means for causing a coolant to flow in a flow path provided in the light modulation element. The respective provided display devices are provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the light modulator and the display device according to the present invention will be described below with reference to FIGS. In the figure, the same components as those described above are designated by the same reference numerals, and detailed description thereof will be omitted. FIGS. 1 and 2 are perspective views of an embodiment of the light modulators SLM1 and SLM2 according to the present invention, and 1a is a transparent substrate BP2 side on which the read light RL enters, for example. BP2
In the channel provided so as to penetrate through the inside, for example, a liquid (for example, water) which is a refrigerant is circulated by a cooling mechanism 10 described later to forcibly cool the light modulation element SLM1. This is to solve the above-mentioned problems by suppressing the temperature rise due to light absorption. 1b is the transparent substrate BP1 side which is the side on which the writing light WL is incident,
In the flow path provided so as to penetrate through the transparent substrate BP1, water, which is a coolant, is circulated in the flow path 1b as described above. As described above, according to the light modulation elements SLM1 and SLM2 of the present invention, the flow path is provided therein without increasing the thickness of the transparent substrate BP1 on the side where the writing light is incident. The thickness does not increase at all, so that it is possible to display a high-resolution image without deteriorating the optical system.

The flow channels 1a and 1b may be formed as through holes or may be formed by bonding a plurality of substrates together. The flow paths 1a and 1b respectively provided in FIG. 2 are shown as being formed by bonding. Further, generally, the relationship between the heat generation amount Q and the temperature increase ΔT is expressed by the following equation. That is, Q = αSΔT, where α is the heat transfer coefficient and S is the heat radiation area. The heat transfer coefficient α is known to be 10 to 100 times larger than that during natural convection when forced liquid cooling is used.
The temperature rise can be suppressed to 1/100 to 1/10 for the same amount of incident light.

FIGS. 3 and 4 are perspective views of one embodiment of the light modulators SLM3 and SLM4 according to the present invention, respectively.
In these figures, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted. 3 and 4, the photoconductive layer member PCL provided in FIGS. 1 and 2 is omitted. That is, the glass substrates BP1 and BP2
Between the transparent electrodes Et1 and Et2 and this transparent electrode Et1
, Et2, a light modulation material layer member PML is arranged between the light modulation elements SLM3 and SLM4. The light modulation elements SLM3 and SLM4 in FIGS. 3 and 4 are, for example,
It is used as a matrix-driven liquid crystal panel. Various driving methods such as an active matrix method in which a TFT (thin film transistor) is attached to each pixel can be considered.

FIG. 5 shows an optical modulator SLM1 according to the present invention.
[Fig. 2] Fig. 2 is a schematic view of an embodiment of a cooling mechanism 10 for cooling the SLM4, in which 2a and 2b are connecting members which are provided, for example, on the upper and lower sides of the light modulation element SLM1, and which are made of, for example, a plastic material. , 3 and 8 are tubes made of vinyl or rubber which are respectively connected to the connecting members 2a and 2b, and 4 is such that the refrigerant flows back in the flow paths 1a and 1b provided in a part of the light modulation element SLM1. This is a configured pump, and for example, a bellows pump or a diaphragm pump is used. Reference numeral 6 denotes a container in which a refrigerant 7, for example, propylene glycol, ethylene glycol, water or the like is stored. Reference numeral 5 is a vinyl or rubber tube for connecting the pump 4 and the container 6 containing the refrigerant 7. Reference numeral 9 is a cooler for cooling the refrigerant 7 whose temperature has risen due to the heat from the light modulation element SLM1, and this cooler 9 is, for example, a radiator (not shown),
It is composed of a fan and the like.

Next, the operation of the cooling mechanism 10 will be described. When the pump 4 operates, the refrigerant 7 contained in the container 6 reaches the connecting member 2a through the tubes 5 and 3 made of vinyl, for example.
a into the flow channel 1a, through which the connecting member 2
b, and further through the cooler 9 and the tube 8 to the container 6
It comes back inside. As a result, the light modulation element SLM1 in a state in which high-power light is incident and heated is cooled.

FIG. 6 shows an optical modulator SLM1 according to the present invention.
FIG. 6 is a perspective view of an embodiment of a display device 20 using (SLM2 to SLM4). In the figure, the same parts as those described above are designated by the same reference numerals, and detailed description thereof will be omitted. An LED array 11 is a writing light source, and N (where N is a natural number of 2 or more) light emitting elements corresponding to N (where N is a natural number of 2 or more) pixels are linearly arranged. Is what you are doing. In addition, this LED
As the array, for example, a structure in which a large number of light emitting elements (light emitting diodes, semiconductor lasers, etc.) are linearly arranged on a substrate, or a microlens array formed on a light emitting element array can be used. The writing light emitted from the N light emitting elements linearly arranged in the LED array 11 is a photoconductive layer member in the light modulating element SLM1 to which the writing light is to be given and which has a cooling mechanism in a part thereof. The writing light has a wavelength that does not largely deviate from the wavelength near the peak value in the spectral sensitivity characteristic curve of PCL, and the writing light is information of N pixels on one straight line in the image to be displayed. The light emission amount according to the above can be simultaneously emitted over a predetermined period. In the description of FIG. 6, the light modulation element SLM1 used here is the same as that described with reference to FIG. 1, so a detailed description thereof will be omitted. The N light fluxes emitted from the N light emitting elements in the LED array in the state where the light emission amount is modulated by the N pixel information are passed through the writing lens L, for example, like an oscillating mirror or a rotating mirror car. It is incident on the optical scanning device 12. Since the oscillating mirror as the optical scanning device 12 is oscillated in the direction of the arrow in the figure at a predetermined cycle, the light flux incident on the oscillating mirror moves at a constant moving speed from the top to the bottom of the light modulator SLM1. Is repeatedly projected on the light modulation element SLM1 and the light is imaged as writing light on the photoconductive layer member PCL of the light modulation element SLM1 and then is written on the light modulation element SLM1. The image information to be displayed is written.

In the display device shown in FIG. 6, a power source E is provided between the transparent electrodes Et1 and Et2 as shown in FIG.
From the transparent substrate BP1 side of the light modulation element SLM1 to which a predetermined voltage is supplied from the optical scanning device 12 described above.
The N writing light fluxes of which the light emission amount is modulated by the image information reflected by the oscillating mirror are incident and are condensed on the photoconductive layer member PCL in the light modulation element SLM1. As for the light modulation element SLM1, since the light having a wavelength that is not largely deviated from the wavelength near the peak value in the spectral sensitivity characteristic curve of the photoconductive layer member PCL in the light modulation element SLM1 is used, the portion where the N writing light fluxes described above are condensed The electric resistance value of the photoconductive layer member PCL changes with high sensitivity in accordance with the amount of light irradiated, and the boundary between the photoconductive layer member PCL and the dielectric mirror DML is subject to the above display. A charge image corresponding to the irradiation light amount of N writing lights whose light emission amount is modulated by the image information,
For example, a charge image in a state in which charges having a charge amount corresponding to N sequential pixel information by time-series signals are arranged well is formed, whereby the light modulation material layer member PML of the light modulation element SLM1. , An electric field due to the N charge images formed at the boundary between the photoconductive layer member PCL and the dielectric mirror DML is applied to.

Reference numeral LS in FIG. 6 is a light source for reading, and from the light source LS for reading, the above-mentioned light modulation element SLM is used.
The read light RL in the visible region is emitted in a state in which the photoconductive layer member PCL of 1 does not contain light in the wavelength region in which the photoconductive layer member PCL has substantial sensitivity. Reference numeral 13 denotes a polarization beam splitter. When the reading light RL emitted from the reading light source LS is incident on the polarization beam splitter 13, the S-polarized light component of the reading light RL is converted into light by the polarization beam splitter 13. The light is reflected by the read side of the modulation element SLM1 and enters from the transparent substrate BP2 on the read side of the light modulation element SLM1. As described above, the light modulation element SL
The read light RL incident from the transparent substrate BP2 side of M1 is
Transparent substrate BP2 → Transparent electrode Et2 → Light modulation material layer member PM
L → Dielectric mirror D L Dielectric mirror DM
The reflected light of the read light that reaches L and is reflected there is dielectric mirror DML → light modulation material layer member PML → transparent electrode Et.
The light is emitted from the light modulation element SLM1 through the path of 2 → transparent substrate BP2 →.

In this way, the N read light beams simultaneously emitted from the light modulation element SLM1 are charge images in a state in which charges of a charge amount corresponding to N sequential pixel information are arranged. Since the light flux is a light flux that travels back and forth through the light modulation material layer member PML to which the electric field is applied, the light flux changes the state of the polarization plane in correspondence with the N sequential pixel information linearly arranged. It is supposed to be. Then, the N read-out lights simultaneously emitted from the light modulation element SLM1 enter the polarization beam splitter 13, and the component of the incident light converted into P-polarized light passes from the polarization beam splitter 13 to the projection lens 14. Simultaneously given, the projection lens 14 simultaneously projects it as N light spots linearly arranged on the screen 15. According to the display device of the present invention, since the cooling mechanism 10 having the cooler 9 is used as the light modulation element SLM1,
Even if high-power light enters the light modulator SLM1,
The temperature does not rise due to light absorption in the element, and therefore a high resolution image is displayed on the screen 15. In the description of the embodiments of the present invention,
Although the display device configured by using the reflection type light modulation elements as the light modulation elements SLM1 to SLM4 has been described, the invention is not necessarily limited to this, and the transmission type light modulation element may be used.

[0018]

As described in detail above, the present invention is, as the first invention, an optical modulation element in which at least a transparent electrode and an optical modulation material layer member are laminated between two relatively arranged substrates, At least the transparent electrode, the photoconductive layer member, between at least one substrate, which is provided with a flow path for allowing a coolant to pass therethrough, and as a second invention, between two substrates that are arranged relative to each other. An optical modulation element comprising a stack of optical modulation material layer members, wherein at least one substrate is provided with a flow path for allowing a coolant to pass therethrough. By configuring the invention, the optical system is not deteriorated, and it is possible to display a high-resolution image. Further, as a third invention, at least the one substrate of the light modulation element in which at least a transparent electrode, a photoconductive layer member, and a light modulation material layer member are laminated between two substrates which are arranged relative to each other, An optical modulation element provided with a flow path for passing a coolant, a writing means for writing desired display information in the light modulation element, a reading means for reading out the display information written in the light modulation element, and the optical modulation element The present invention provides a display device including means for flowing a coolant in the flow path provided in the above. Even if high output light is incident on the light modulation elements SLM1 to SLM4 by such a configuration, the light is generated within the element. Since the temperature does not rise due to absorption, a high-resolution image can be displayed on the screen.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a light modulation element according to the present invention.

FIG. 2 is a perspective view of an embodiment of a light modulation element according to the present invention.

FIG. 3 is a perspective view of an embodiment of a light modulation element according to the present invention.

FIG. 4 is a perspective view of an embodiment of a light modulation element according to the present invention.

FIG. 5 is a schematic view of an embodiment of a cooling mechanism for cooling the light modulation element according to the present invention.

FIG. 6 is a perspective view of an embodiment of a display device using the light modulation element according to the present invention.

FIG. 7 is a side view of the light modulation element.

FIG. 8 is a characteristic curve diagram showing characteristics of spatial frequency and resolution.

[Explanation of symbols]

BP1, BP2 transparent substrate Et1, Et2 transparent electrodes PCL photoconductive layer member PML light modulation material layer member SLM light modulator 1a, 1b flow path 10 Cooling mechanism 11 Writing light source 12 Optical scanning device 13 Beam splitter Light source for LS readout

Continued front page    (72) Inventor Tetsuji Suzuki             3-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa             Local Victor Company of Japan, Ltd. (72) Inventor Tatsumi Reiko             3-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa             Local Victor Company of Japan, Ltd. (72) Inventor Ryusaku Takahashi             3-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa             Local Victor Company of Japan, Ltd. (72) Inventor Keiichi Maeno             3-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa             Local Victor Company of Japan, Ltd.

Claims (3)

[Claims] 1. A light modulation element comprising at least a transparent electrode and a light modulation material layer member laminated between two substrates arranged relative to each other, wherein at least one of the substrates is provided with a passage for allowing a coolant to pass therethrough. An optical modulator characterized by being provided. 2. A light modulation element comprising at least a transparent electrode, a photoconductive layer member and a light modulation material layer member laminated between two substrates which are arranged relative to each other, and a refrigerant is passed through at least one of the substrates. An optical modulation element, which is provided with a flow path for making it. 3. A cooling medium is passed through at least one substrate of an optical modulation element in which at least a transparent electrode, a photoconductive layer member, and a light modulation material layer member are laminated between two substrates which are arranged relative to each other. A light modulating element provided with a flow path, a writing means for writing desired display information in the light modulating element, a reading means for reading the display information written in the light modulating element, and a light modulating element provided in the light modulating element. And a means for causing a coolant to flow in the flow path.