JPH08114766A - Optical write type display device - Google Patents

Abstract

PURPOSE: To enhance energy efficiency and to make a device compact by constituting the device of a spatial light modulation element, a polarization/ analyzation means and an amplitude dividing beam splitter for dividing an amplitude of write light. CONSTITUTION: An optical write type display device writes the write light having image information on the light receiving surface of the write light of the spatial light modulation element (SLM) 5 by the amplitude dividing beam splitter(BS) 6 arranged on the write light side as left/right inverted images with the same intensity and the same size. Then, the light from a light source for read-out is polarization separated into a P polarized light and an S polarized light by the polarizing beam splitter(PBS) 4 for both polarization type polarizer/ analyzer provided on a read-out light side, and the areas of the corresponding SLM 5 are irradiated by the P polarized light and the S polarized light, and by synthesis and analyzation of two reflected modulation light and an inversion action of left/right images, the read-out light source light is substantially utilized by nearly 100%. Thus, the display luminance of the device is improved, and the device is made compact, and energy is saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing type image display device for displaying a high brightness image.

[0002]

2. Description of the Related Art Conventionally, as an optical writing type image display device for displaying a high brightness image, a device as shown in FIG. 4 has been known. In FIG. 4, the white light from the reading light source (20) is a polarizing beam splitter (PB) that acts as a polarizer and an analyzer.
(21), which is separated into P-polarized light and S-polarized light, which transmits P-polarized light and reflects S-polarized light.

The reflected S-polarized light is a spatial light modulator (Spatial
Light Modulation): Hereinafter referred to as "SLM") (22). Image information is written in the SLM (22) by the writing means (25), and the polarization of incident light (S-polarized light reflected by PBS) is modulated and reflected according to the written image information. Of the reflection-modulated light from the SLM (22), only P-polarized light, which is a pure modulation component, is transmitted and analyzed by the PBS (21) and projected as display light on the screen (24) by the projection lens (23).

[0004]

However, in the photo-writing type image display device according to the above-mentioned conventional technique, the reading light incident on the PBS (21) from the reading light source (20) is separated by the polarization separation film. P-polarized light is SLM (2
It is discarded without incident on 2), and half of the light energy of the light source is not used. This is an obstacle to making the device compact and saving energy.

The object of the present invention is to be highly energy efficient,
An object of the present invention is to provide a compact optical writing type image display device and further a compact optical writing type stereoscopic image display device.

[0006]

In order to achieve the above object, the photo-writing type image display device according to the present invention has the following constitution. For example, as shown in FIG. 1, in the photo-writing type image display device according to the present invention, the polarization state of the read-out light which is polarized by being incident on the polarization beam splitter for both polarization type polarizer / analyzer depending on the intensity of the writing light. A spatial light modulator (5) for modulating, a polarization and light detecting means (4) for polarizing the read-out light that has been incident, and detecting and extracting only the modulation component of the reflected light from the spatial light modulator. In a photo-writing type image display device having a projection means (11) for projecting light on a screen and a reading light generating means (1) for entering the polarization / analysis means, a light receiving surface of the writing light and an incident polarized light A spatial light modulator (5) having two adjacent areas on each of the light-receiving surfaces, a polarization beam splitter (4) for both polarization type polarizer / analyzer as polarization / analyzing means, and an amplitude of writing light is divided. As that means,
It is composed of an amplitude splitting beam splitter (6). The polarization beam splitter (4) for both polarization type polarizer / analyzer, which is a polarization / analysis means, has an isosceles triangle (including an equilateral triangle) in which the straight sides of two right-angled triangular original prisms are joined. With one double prism structure (4)
An optical thin film group (4a) capable of polarization splitting on at least one of the joint surfaces of the two right triangle original prisms.
Light is incident from one of the hypotenuses of the two original prisms, and the incident light is separated by the optical thin film group (4a) into two linearly polarized lights whose polarization planes are orthogonal to each other. The linearly polarized lights are totally reflected by the inner surfaces of the slant surfaces of the two original prisms, travel in parallel with each other, and are emitted from the non-bonded straight sides of the original prisms, respectively, and the target object (5) to be irradiated. After entering and reflecting on different portions of the original prisms, entering the straight sides of the original prism which are not joined, and proceeding in parallel to each other, after total reflection on the inner surfaces of the slopes of the two original prisms, the optical thin film It is characterized in that a polarization component which is combined in the group (4a) and is modulated by reflection in the target object (5) in the combined light is extracted from the other hypotenuse of the two original prisms as analysis light. This is the configuration.

[0007]

In the case where the cross section of both polarization type polarizer / analyzer polarization beam splitters formed by joining the right sides of two right triangle original prisms is an equilateral triangle, the light from the light source for reading is For both polarization type polarizer / analyzer, which is formed by making the incident angle 0 ° to one hypotenuse of the two original prisms and joining the right sides of two right triangle original prisms. When the cross section of the polarization beam splitter is an isosceles equilateral triangle, the light from the reading light source has an incident angle of 0 ° to 90 ° with respect to one hypotenuse of the two original prisms.
By making the light incident in the range of °, the incident light is separated by the optical thin film group (4a) into two linearly polarized lights whose polarization planes are orthogonal to each other, and the two linearly polarized lights are respectively formed on the inner surfaces of the inclined surfaces of the two original prisms. After total reflection, proceed parallel to each other,
The light is emitted from the non-bonded straight sides of the original prism, is made incident on different portions of the target object (5) which is the irradiated body, is reflected, and then is made incident on the non-bonded straight sides of the original prism. , Travel in parallel with each other and undergo total reflection on the inner surfaces of the slant surfaces of the two original prisms, and then are combined by the optical thin film group (4a) and modulated by the reflection at the target object (5) of the combined light. The polarized component thus generated can be taken out as analysis light from the other hypotenuse of the two original prisms.

Amplitude splitting beam splitter or polarization beam splitter for both polarization type polarizer / analyzer on which a light beam from a writing light source enters, and polarization beam splitter / analyzer polarization beam for both polarization type on which a light beam from a reading light source enters. The splitter is not limited to have the same shape and the same size. The optical writing type display device receives the writing light having the image information by the amplitude dividing BS provided on the writing light side and receives the writing light of the SLM (first area (5aa),
In the second area (5bb)), the horizontally reversed image of the same intensity and the same size is written.

The light from the reading light source is separated into P-polarized light and S-polarized light by the polarization beam splitter for both polarization type polarizer and analyzer provided on the read-out light side, and P-polarized light and S-polarized light correspond to each other. Light-receiving surface of read light of SLM (P polarized light is in the third region (5a), S polarized light is in the fourth region (5a)
b)) is irradiated and reflected, and the read light source light can be practically used almost 100% by the combination of the modulated light which is modulated according to the intensity of the writing light, the light detection and the inversion action of the left and right images.

[0010]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to this embodiment. [First Embodiment] FIG. 1 is an explanatory diagram of the first embodiment.

The SLM (5) is composed of a photosensitive layer, a light-shielding layer, a dielectric mirror layer, and a liquid crystal layer in order from the incident direction of the writing light between two transparent electrodes. The light shielding layer and the dielectric mirror layer insulate the reading light and the writing light, and the dielectric mirror layer plays a role of reflecting the reading light and returning it to the reading light side. These four constituent layers are connected to an AC power source (not shown).
The two transparent electrodes are electrically connected in series substantially in the layer thickness direction.

The liquid crystal layer has a nematic liquid crystal structure, and has a twist angle of 45 °, a tilt angle of 2 ° and a layer thickness of 4 μm. The liquid crystal layer has the long axis of the liquid crystal molecules on the light reading side, which is oriented in the vibration direction of P-polarized light. When writing light is incident on the photosensitive layer, its impedance decreases in proportion to the intensity of the writing light, and as a result, the divided voltage applied to the liquid crystal layer increases.

When the voltage applied to the liquid crystal layer is below the threshold value, P
Polarized light and S-polarized light receive 45 ° optical rotation, but after being reflected by the dielectric mirror, they receive 45 ° optical rotation in the opposite direction, so after being emitted from SLM (5), the result is the same polarization as in the case of an isotropic medium. There is no change in state. When the voltage applied to the liquid crystal layer is equal to or higher than the threshold value, the liquid crystal molecules start to rise and the liquid crystal becomes birefringent.

The light beam from the writing light source (10) passes through the condenser lens (9) and illuminates the transmissive liquid crystal panel (8). Image information is written in the transmissive liquid crystal panel (8), and the light beam transmitted through the transmissive liquid crystal panel (8) has image information as writing light. The writing light is amplitude-splitting BS by the imaging lens (7).
After the incidence on (6), the action of the amplitude division thin film (6a) (the amplitude division thin film (6a) of the amplitude division BS (6) shows the intensity ratio of the reflected light and the transmitted light over the entire spectral range of the writing light. With the function of dividing into almost one-to-one), two pieces of image information of the same intensity and the same size, which are horizontally inverted with respect to the amplitude division thin film, are written in the areas (5aa) and (5bb) of the SLM (5), respectively. . That is, the liquid crystal layer (liquid crystal molecules) has birefringence according to the written image information (intensity of writing light).

On the other hand, a light beam from the reading xenon lamp light source (1) passes through an infrared / ultraviolet light cut filter (not shown) and a condenser lens (2), and a reflecting mirror (3) (this is an essential component). (It is not a requirement) and is incident on the PBS (4) for both polarization type polarizer and analyzer.
The incident light is split into P-polarized light and S-polarized light by the action of the polarization splitting thin film (4a), and after being totally reflected on the inner surfaces of the prisms, travel in parallel with each other, and the light-receiving surface area (5) of the incident polarized light of the SLM (5).
It is vertically incident on a) and (5b).

The incident P-polarized light and S-polarized light are reflected by the dielectric mirror layer, and when the P-polarized light and S-polarized light are emitted from the SLM (5), the P-polarized light is given an S-polarized component according to the intensity of the writing light. , Elliptically polarized light, S polarized light is given a P polarized light component according to the writing intensity, and is converted to elliptically polarized light.
Each elliptically polarized light emitted from points on (5a) and (5b) corresponding to the light receiving surfaces (5aa) and (5bb) of the writing light has a modulated light component of the same intensity.

That is, the S-polarized light component, which is the P-polarized light modulation component, and the P-polarized light component, which is the S-polarized light modulation component, have equal intensities, and the major axis directions of the elliptically polarized lights are orthogonal to each other. Each of the elliptically polarized lights goes back through the optical path in the biprism and is combined and detected by the polarization separation thin film portion (4a), and each S-polarized component and P-polarized component is screened by the projection lens (11) as image information by the projection lens (11). Displayed above.

Here, the area (5aa) of the SLM (5),
The left-right inverted image written in (5bb) is transferred to the reading light side while maintaining the left-right inversion, and the left-right inverted image is left-right inverted by the PBS (4) for both polarization type polarizer and analyzer. The correct image of will be displayed. [Second Embodiment] FIG. 2 is an explanatory view of the second embodiment. The stereoscopic image can be displayed, and the polarization splitter / analyzer PBS (13) having the same function as that used by the amplitude splitting BS (6) on the reading light side is different from that of the first embodiment. ), And a liquid crystal optical switch (14) is added between the transmissive liquid crystal panel (8) and the imaging lens (7).

The transmissive liquid crystal panel (8) is manufactured so as to transmit P-polarized light and alternately displays image information corresponding to the left eye system and image information corresponding to the right eye system. The display period of P-polarized light having image information corresponding to the left-eye system and P-polarized light having image information corresponding to the right-eye system is 30 Hz or more, which is the limit at which the human eyes do not feel flicker in the entire image including the left and right images. It can be switched at 60Hz or higher.
The liquid crystal optical switch (14) opens and closes in synchronization with the switching timing of the image information corresponding to the left eye system and the image information corresponding to the right eye system.

That is, the transmissive liquid crystal panel displays left eye system information in the first half cycle of the display cycle of the entire image including left and right images, and right eye system information in the latter half cycle. Of course, the order of left and right is determined for convenience of description, and is not limited to this. Liquid crystal optical switch (14) is 90
It consists of a twisted liquid crystal cell, which rotates the polarization plane of transmitted light by 90 degrees when no voltage is applied, but has the function of transmitting the incident linearly polarized light as it is without rotation when a voltage is applied.

When the P-polarized light having the image information corresponding to the left eye system is displayed, the liquid crystal optical switch (14) is in the open state to convert the P-polarized light having the image information corresponding to the left eye system into S-polarized light. When displaying P-polarized light having image information corresponding to the right eye system, the liquid crystal optical switch (1
4) is in a closed state, and P-polarized light having image information corresponding to the right eye system is transmitted as it is.

That is, S-polarized light corresponds to left-eye image information, and P-polarized light corresponds to right-eye image information. S-polarized light and P-polarized light are written by the writing dual-polarization polarizer / analyzer PBS (13), and the S-polarized light corresponding to the left eye image in the first half cycle of the display cycle is the writing light receiving surface of the SLM (5). Of the writing light receiving surface (5aa) on the writing light receiving surface on the area (5bb) of
Image on top.

Next, the S-polarized light incident on the area (5b) on the light receiving surface for reading light is given a P-polarized component according to the intensity of the S-polarized light corresponding to the left-eye image information written on (5bb). , Converted to elliptically polarized light. The P-polarized light that has entered the area (5a) on the readout light receiving surface is given an S-polarized component according to the intensity of the P-polarized light corresponding to the right-eye image information written on (5aa), and is converted into elliptically polarized light. It

Each of the elliptically polarized lights goes back through the optical path in the biprism and is synthesized and analyzed by the polarization separation thin film (4a), and the left eye image (S polarization) and the right eye image (P polarization) are alternately the same. Display on screen. When you watch the screen,
The left eye wears polarized glasses that transmit only S-polarized light and the right eye transmits only P-polarized light. In this way, a stereoscopic image is obtained.

What is important here is the relationship between the time constant (rise and fall times) of the SLM (5) and the display cycle of the display image information of the transmissive liquid crystal panel. When the time constant of the SLM (5) is sufficiently shorter than the display cycle of the display image information of the transmissive liquid crystal panel (8), the utilization efficiency of the reading xenon lamp light source (1) is almost 50%. When the rising time constant of (5) is as long as 10 msec or more, if the display cycle of the display image information of the transmissive liquid crystal panel (8) is made equal to or less than the time constant, the reading xenon lamp light source (1) is used. It is possible to improve efficiency. In this case, if the display cycle is set to 10 msec or less, the utilization efficiency can be substantially approached to 100%.

[0026]

As described in detail above, according to the present invention, the optical writing type display device allows the writing light having the image information to be slid by the amplitude dividing BS provided on the writing light side.
On the light receiving surface of the writing light of M, left and right reversed images having the same intensity and the same size are written. Then, the light from the light source for reading is P for both polarization type polarizer / analyzer provided on the reading light side.
The polarized light is separated into P-polarized light and S-polarized light by BS,
The polarized light is applied to the corresponding SLM area, and by combining the two reflection-modulated lights, the analysis, and the inversion function of the left and right images, substantially 100% of the read light source light can be used, which improves the display brightness of the device. It is possible to greatly reduce the size of the device and save energy.

By replacing the amplitude dividing BS on the writing light side with a PBS for both polarization type polarizer / analyzer and a liquid crystal optical switch, and further synchronizing the time constant of the SLM and the display cycle of the transmission type liquid crystal panel, Since substantially 100% of the reading light source light can be used, the display brightness of the device can be improved, the device can be made compact, and the energy can be saved significantly.

[Brief description of drawings]

FIG. 1 is an optical layout diagram of an optically writable image display device according to a first embodiment of the present invention.

FIG. 2 is an optical layout diagram of an optical writing type stereoscopic image display device according to Example 2 of the present invention.

FIG. 3 is an SLM used in the optical writing image display device of the present invention.
It is explanatory drawing which shows the division area of.

FIG. 4 is an optical layout diagram of a conventional example.

[Explanation of symbols]

1, 20 Read-out xenon lamp light source 2 Condenser lens 3 Reflector 4, 13 Dual-polarization polarizer / analyzer PBS 4a, 13a Polarization separation thin film 5, 22 SLM 5a, 5b Read-out light side area on SLM 5aa, 5bb Area on the writing light side on the SLM (no visible boundary) 6 BS for amplitude division 6a Amplitude division thin film 7 Imaging lens 8 Transmissive liquid crystal panel 9 Condenser lens 10 Light source for writing 11, 23 Projection lens 12, 24 Screen 14 LCD optical switch 21 PBS 25 Writing means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuhiko Katano 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (4)

[Claims] 1. A single biprism structure in which the right sides of two right-angled triangular original prisms are joined together to form an isosceles triangle, and at least one of the joining surfaces of the two right-angled triangular original prisms is formed. An optical thin film group capable of polarization splitting is provided on one surface, light is incident from one hypotenuse of the two original prisms, and the incident light has polarization planes orthogonal to each other due to the optical thin film group. Split into two linearly polarized light, and the two linearly polarized light are
After total internal reflection on the inner slopes of the two original prisms,
The parallel prisms travel in parallel with each other, are emitted from the unbonded straight sides of the original prism, are incident on different portions of the target object that is the irradiated object, and are reflected, and then are the unbonded straight sides of the original prism. Polarized light that has been incident on the optical system and has traveled in parallel to each other, and has undergone total internal reflection on the slanted inner surfaces of the two original prisms, and then has been combined by the optical thin film group, and has been modulated by reflection from the target object in the combined light. A polarization beam splitter for both polarization type polarizer and analyzer, wherein the component is extracted from the other hypotenuse of the two original prisms as analysis light. 2. A spatial light modulation element for modulating the polarization state of read-out light which is incident upon the polarization beam splitter for both polarization type polarizer and analyzer according to the intensity of write-in light, and the incident read-out light. Polarization / analysis means for polarizing and detecting only the modulated component of the reflected light from the spatial light modulator, projection means for projecting the analysis light on the screen, and incidence on the polarization / analysis means. In the photo-writing type image display device having the reading light generating means, the light receiving surface of the writing light and the light receiving surface of the reading light polarized by being incident on the polarization beam splitter for both polarization type polarizer and analyzer are 2 respectively. A spatial light modulator having a divided adjacent region, a polarization beam splitter for both polarization type polarizer / analyzer according to claim 1 as polarization / analysis means, and an amplitude of writing light. An optical writing type image display device characterized by using a beam splitter for amplitude division as means. 3. The photo-writing type image display device according to claim 2, wherein the first area irradiated by the amplitude-divided first writing light and the second area irradiated by the amplitude-divided second writing light. And a P-polarized light of the read light from the polarization / analysis means, and a reflected light modulated according to the intensity of the write light is read. Of the third region corresponding to the first region which reverses the optical path of the P-polarized light and the S-polarized light of the reading light from the polarization / analysis means, and the reflected light modulated according to the intensity of the writing light. Is incident on and polarized by a polarization beam splitter for both polarization type polarizer / analyzer having a fourth region corresponding to the second region which is reverse to the S-polarized light path of the readout light and two adjacent regions. It consists of the receiving surface of the read light Optical writing type image display device according to claim 2, characterized in that it comprises a serial spatial light modulator. 4. The dual polarization type polarizer / analyzer according to claim 1, wherein an amplitude splitting beam splitter is used as an element component of the writing light generating means in the optical writing type image display device according to claim 2 or 3. Optical writing type stereoscopic image display device characterized by arranging a polarizing beam splitter for LCD and a liquid crystal optical switch.