JP2008139700A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To practice pixel shifting technique for attaining higher definition of an image display device by simple constitution with high accuracy. <P>SOLUTION: The image display device has an image display element 8, a light source unit 4 which is composed of two light sources 1 and 2 irradiating the image display element 8 with light of polarization directions orthogonal to each other and a birefringent element 6 which is installed at a side where light is emitted from the image display element 8 and has an optical axis in a direction inclined to an emission light axis. Thereby light utilization efficiency is made higher as compared with a case when non-polarized light is linearly polarized and a polarization surface is controlled. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image display device, and more particularly to an image display device that uses an image display element to achieve high definition.

  “Pixel shift technology” refers to an image display element in which a plurality of pixels that can control light according to image information is two-dimensionally arranged, a light source that illuminates the image display element, and an image pattern displayed on the image display element. An optical member for observing the optical field, and a light deflecting means for deflecting the optical path between the image display element and the optical member for each of a plurality of subfields obtained by dividing the image field in time. Means a light deflecting means in a display device that displays an image pattern in which the display position is shifted in accordance with the deflection of the optical path for each field, thereby multiplying the apparent number of pixels of the image display element. . In the description of the present specification, the “polarization direction of linearly polarized light” refers to the vibration direction of the electric field vector in linearly polarized light.

Prior art examples relating to such a pixel shift technique are disclosed in Patent Documents 1 and 2, for example.
Patent Document 1 discloses a pair of transparent substrates, a liquid crystal consisting of a chiral smectic C phase having a homeotropic orientation filled between the substrates, and at least one set of electric field applying means for applying an electric field to the liquid crystal. Compared to the conventional optical deflection element, the configuration including the high cost, the large size of the apparatus, the light quantity loss, and the optical noise can be improved due to the complicated configuration “optical deflection method, optical deflection element, optical deflection device And an image display device ”.
Patent Document 2 discloses a pair of transparent substrates, a plurality of spacers that regulate the distance between both substrates, a transparent resistor layer provided on at least one substrate surface, and a chiral smectic C phase within the distance between both substrates. Connected to at least two of the liquid crystal layer, the alignment layer for aligning the liquid crystal layer so that the normal direction of the chiral smectic C phase is substantially perpendicular to the substrate surface, and the transparent resistor layer Even when the effective cross-sectional area of the optical path is large, the entire optical path can be deflected relatively uniformly and efficiently by the configuration having a plurality of electrodes “an optical deflecting element and an optical deflecting device using the same, and An “image display device” is disclosed.

  The conventional pixel shift technology as disclosed in Patent Documents 1 and 2 is a method of swinging an optical element of an image display element or a projection optical system, or using a light deflecting element such as a liquid crystal. However, since the former swing method involves mechanical vibration, durability of the image display element and the optical element is required, and heat and noise are generated due to the mechanical vibration. The latter liquid crystal method is excellent in terms of mechanical reliability, but it requires a technique for controlling the liquid crystal alignment, and there is a problem that the cost for forming the device is high.

  On the other hand, an image display device using a digital micromirror device (hereinafter referred to as “DMD”: Texas Instruments Incorporated) has been developed. Among the image display devices using DMD, there is a device designed for colorization by a field sequential color method using a color wheel. This device will be described below with reference to the drawings.

  FIG. 10 is a schematic diagram showing a configuration of a conventional image display apparatus. In FIG. 10, a light beam emitted from a lamp unit having a white light source such as a high pressure mercury lamp or a xenon lamp has the configuration shown in FIG. 11, and when passing through a rotating color wheel, red (R), green ( G) Each color is switched to blue (B). Light emitted from the color wheel is guided to a rod integrator for improving the uniformity of light intensity by the lens, and irradiated to the DMD through the condenser lens. DMD is an image display element in which pixels made of micromirrors are two-dimensionally arranged. By switching the mirror angle for each pixel according to the image signal corresponding to each pixel, and controlling the length of time reflected in the direction of the projection lens and the length of time reflected in the direction other than the projection lens, it is predetermined for each pixel. To get the brightness.

As a prior art example for improving the definition and smoothing of the DMD, since it is realized by the swing method as in the above-mentioned Patent Document 1, it has the same problem as described above.
JP 2002-328402 A JP 2003-098504 A Japanese Patent Laid-Open No. 2004-070365

  In the present invention, light irradiating an image display element such as a DMD is set to linearly polarized light whose polarization direction is switched over time, and the emitted light is transmitted through a birefringent plate, thereby performing pixel shift depending on the polarization direction. An object of the present invention is to provide an image display device that can be used.

  In addition, in the image display apparatus using DMD, a structure in which the above-described optical device is installed and the polarization direction of light emitted from the light source by the optical device is switched is also conceivable. Will drop slightly.

  Therefore, an object of the present invention is to provide an image display apparatus having a novel structure for obtaining the same effect without installing an optical device.

  In order to achieve such an object, the invention described in claim 1 is directed to an image display element, a light source unit including two light sources that irradiate the image display element with light having polarization directions orthogonal to each other, and light from the image display element. And a birefringent element having an optical axis in a direction inclined with respect to the outgoing optical axis.

  According to a second aspect of the present invention, in the first aspect of the present invention, light is emitted alternately from each light source of the light source unit.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, a plurality of light sources are provided corresponding to light of three or more colors.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the light source is a laser that emits linearly polarized light.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the polarization direction of the light rays alternately incident on the image display element is perpendicular to the diagonal direction of the pixels in the image display element, or It is characterized by parallel directions.

  The invention according to claim 6 is the invention according to any one of claims 1 to 4, wherein the polarization direction of the light rays alternately incident on the image display element is perpendicular or parallel to the side direction of the pixels in the image display element. It is characterized by being in a different direction.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the polarization direction of the light beam emitted from the image display element and incident on the birefringent element is the optical axis of the birefringent element. It is characterized by being in a state parallel to and perpendicular to the plane including the optical axis.

  The invention according to claim 8 is the invention according to claim 7, characterized in that the amount of deflection of the parallel light beams by the birefringence elements is a half pitch of the pixel array of the image display elements in the deflection direction.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the display rewriting timing of the image display element and the switching timing of the polarization state of the light source are synchronized. To do.

  According to a tenth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the light amount of the light source is modulated in synchronization with a display rewriting timing of the image display element.

  According to the present invention, in the image display device, it is possible to increase the light use efficiency as compared to the case where the non-polarized light is linearly polarized to control the polarization plane.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

Details of Example 1 of the present invention will be described below.
The configuration of the image display apparatus according to the first embodiment is shown in FIG. As shown in FIG. 1, the image display apparatus according to the first embodiment includes an image display element 8, a light source unit 4 including two light sources 1 and 2 that irradiate the image display element 8 with light in polarization directions orthogonal to each other, an image This is an image display device having a birefringent element 6 provided on the side from which light is emitted from the display element 8 and having an optical axis in a direction inclined with respect to the outgoing optical axis.

  As described above, since the birefringent elements are arranged in the direction inclined with respect to the outgoing optical axis by irradiating light in the polarization directions orthogonal to each other, the pixel shift technique for achieving high definition of the image display device Can be performed with high accuracy with a simple configuration, and the light utilization efficiency is higher than when the non-polarized light is linearly polarized and the polarization plane is controlled.

  In FIG. 1, the image display element 8 shows a reflection type case such as DMD. As the image display element 8, a type that forms an image by modulating the polarization direction of outgoing light using a liquid crystal is commercially available. In Example 1, the incident polarization state and outgoing polarization of the image display element are used. It is easier to handle when the state does not change, and DMD is more preferable.

  As described above, in the first embodiment, by using the DMD, the intensity of light emitted from the image display element does not depend on the polarization state, so that the pixel shift (so-called pixel shift) is favorably performed without affecting the image. Yes. Further, the image display element is managed by dividing the image display element into a plurality of block pixel groups. When rewriting the image display for this image display element, since it is rewritten in several blocks, instead of sequentially switching on the image display element, as described later, illumination switching With the means 5, the polarization state is switched in one plane, so that it is possible to easily obtain the timing when the image display element is rewritten in one plane or divided into several blocks and batch rewrite is performed in the block.

  As shown in FIG. 1, two semiconductor lasers are provided as the light sources 1 and 2. Since the outgoing light of a semiconductor laser (HEMT laser) is linearly polarized light, the optical axis is set on the same optical path as two orthogonal linearly polarized light via a polarizing beam polarizer (PBS) 3 as shown in FIG. Can be overlapped. In FIG. 1, each of the light sources 1 and 2 is shown as a single laser, but may be constituted by a plurality of lasers in order to increase the amount of light.

  As described above, in the first embodiment, since a linearly polarized light at the time of emission from a semiconductor laser or the like is used as a light source, a structural difference that a polarization conversion mechanism is not necessary can be obtained. Can be suppressed. Further, according to a light source such as a semiconductor laser, power is not consumed during a period in which the image display element is not irradiated with light, so that power consumption can be reduced. In addition, according to a light source such as a semiconductor laser, a color reproduction region can be widened and an image excellent in color rendering can be formed. Further, according to a light source such as a semiconductor laser, the light amount can be directly modulated, and the intensity modulation of the light source described later can be easily performed.

  As shown in FIG. 1, illumination switching means 5 is connected to each of the light sources 1 and 2 and is controlled so as to emit light alternately from the light sources 1 and 2 of the light source unit 4.

  As described above, in the first embodiment, the polarization state is not sequentially switched on the image display element 8 by realizing the light emission control method using the illumination switching unit 5 in order to perform the pixel shift. Since the polarization state is switched in a lump, the timing is easy to achieve when rewriting the image display element 8 is lump in a lump or when rewriting is divided into several blocks.

  In FIG. 1, as the PBS 3 in the light source unit 4, a commercially available one such as glass PBS, wire grid PBS (Moxtek) can be used. An optical element for suppressing the speckle pattern of the laser and an optical element for homogenizing the illuminance distribution may be inserted in the optical path from the PBS 3 to the image display element 8 so that depolarization does not occur. There is a need to.

  In FIG. 1, the material of the birefringent element 6 is a material having a large primary electro-optic effect (Pockels effect) such as KH2POO4 (KDP), NH4H2PO4 (ADP), LiNbO3, LiTaO3, GaAs, CdTe, KTN, SRTiO3. , CS2, nitrobenzene, and other materials having a large secondary electro-optic effect can be used.

  FIG. 2A is a diagram showing the structure of the birefringent element 6 used in this embodiment. As shown in FIGS. 2A and 2B, the optical axis is provided in a direction inclined with respect to the optical axis. Here, for the sake of simplicity, it is assumed that the optical axis and the surface of the birefringent element 6 are perpendicular to each other.

  Now, in the orthogonal coordinate system described in FIG. 2, when the light beam has a polarization direction in the x direction as shown by the light beam 1 in FIG. 2B, that is, the optical axis and the optical axis of the birefringent element 6 are included. When in a state perpendicular to the plane, this polarized light behaves as ordinary light and travels straight through the birefringent element 6. On the other hand, as shown in the light ray 2, when the light ray has a polarization direction in the y direction, that is, when it is parallel to the plane including the optical axis and the optical axis of the birefringent element 6, this polarization behaves as extraordinary light. The inside of the birefringent element 6 is deflected. When there is a direction of linearly polarized light in other directions, a straight traveling component and a deflecting component are generated.

  Therefore, the polarization direction of the light beam that exits the image display element 8 shown in FIG. 1 and enters the birefringent element 6 while switching the polarization direction with respect to time is such that the plane of the birefringent element 6 including the optical axis and the optical axis. By switching between a parallel state and a vertical state, straight travel and deflection can be controlled.

  As described above, in the first embodiment, since the relationship between the polarization direction for preventing ghosting and the optical axis direction of the birefringent element is realized, the pixel shift can be achieved only by arranging the birefringent element so as to satisfy this relationship. It becomes possible. In other words, compared to the pixel shift method in which the optical elements of the image display element and the projection optical system are swung or the light deflecting element such as a liquid crystal is used, the light is controlled on the illumination side. A good pixel shift can be performed without increasing the back focus of the projection optical system.

  Also, by setting the shift amount s of abnormal light to a half pitch of the image display element pixel array, high-quality images can be obtained because pixels are equally interpolated.

  As described above, in the first embodiment, when the pixel shift is performed, the relationship between the birefringent element for shifting to an appropriate position and the pixel pitch is realized, and thus the shift to a position corresponding to a half pitch of the pixel array is performed. Thus, a high-definition image can be obtained. The deflection amount can be set by adjusting the ordinary light refractive index, extraordinary light refractive index, optical axis direction, and element thickness of the birefringent element.

Next, the pixel shift direction and position according to the first embodiment will be described.
FIG. 3A shows a case where the pixel shift direction is a diagonal direction of a rectangular pixel (pixel) in the image display element 8. In this case, the polarization direction of the light beam from the light source unit is a direction perpendicular or parallel to the diagonal direction of the pixel of the image display element 8. PS1 position and PS2 position shown in the figure are image positions of the image display element formed on the screen by the straight light and the deflected light.

  As described above, in the first embodiment, when the pixel shift is performed, the relationship between the polarization direction for shifting in an appropriate direction and the arrangement of the image display elements is realized. It is possible to shift the pixel at a high rate, and high definition can be achieved efficiently.

  In FIG. 3B, the pixel shift direction is the side direction of the pixels in the image display element. In this case, the polarization direction of the light beam from the light source unit is the same as the side direction of the rectangular pixel (pixel) of the image display element 8. Take a vertical or parallel direction. In FIG.3 (b), it has shifted to the y direction of the vertical direction, ie, the orthogonal coordinate system in a figure.

  As described above, in the first embodiment, when the pixel shift is performed, the relationship between the polarization direction for shifting in an appropriate direction and the arrangement of the image display elements is realized. Therefore, the vertical and horizontal scanning lines are interpolated. It is possible to shift the pixel to the position where it is to be performed, and high definition can be achieved efficiently. For example, even if the number of pixels in the sub-scanning direction of the image display element is half of 360 for 720 scanning lines that are the D4 standard of HDTV, an image equivalent to 720 is obtained by pixel shift.

  3B, 2 and 1, the relationship between the pixel shift direction, the polarization state of the light source and the optical axis of the birefringent element is shown. As shown in FIG. 3B, when the orthogonal coordinates are selected and the y direction is the shift direction, this coordinate system corresponds to the orthogonal coordinates of FIGS. From FIG. 2, the optical axis is included in the yz plane, but the pixels of the image display element also shift in this direction. If the PS1 position is the position formed by the ray 1 in FIG. 2, that is, the ordinary ray, the polarization direction in this case is set to the x direction.

  On the other hand, if the PS2 position is a position formed by the light ray 2, that is, the extraordinary ray, the polarization direction in this case is the y direction. In the orthogonal coordinate system in FIG. 1, when the optical system is arranged so that the pixel shift is performed in the y direction, it can be seen that the light from the light source 1 corresponds to ordinary light, and the light from the light source 2 corresponds to abnormal light. . Therefore, when illuminated by the light source 1, the PS1 position is taken, and when illuminated by the light source 2, the PS2 position is taken.

  FIG. 4 is a diagram illustrating an example of time distribution of On / Off of the light source, the polarization state on the image display element, the image display element driving signal, and the pixel shift position in the image display apparatus of the first embodiment. In FIG. 4, one image field is divided into two subfields according to the position of the pixel shift in this case. The image display element is fed with an image signal corresponding to each subfield, that is, each pixel shift position. When one field is driven at 60 Hz, the subfield frequency is 120 Hz.

  As shown in FIG. 4, by synchronizing the display rewriting timing of the image display element and the illumination switching timing, an image blur at the time of pixel shift does not occur and a good high-definition image can be obtained. This synchronization can be performed by detecting a vertical synchronization signal of an image input signal to the image display device and generating a signal for display rewriting timing and a signal for illumination switching timing.

  As described above, in the first embodiment, when the pixel shift is performed, the relationship between the appropriate image display element display switching timing and the optical device deflection state switching timing is realized, so that a ghost due to timing failure does not occur. A good high-definition image can be obtained.

  In the first embodiment, the configuration example of the image display apparatus in the case of a monochromatic laser is shown in FIG. 1, but in the second embodiment, as shown in FIG. An image display apparatus having a configuration in which a plurality of colors corresponding to light of colors or more are provided will be described.

  As shown in FIG. 5, the image display apparatus according to the second embodiment has three colors (R [red], G [green], and B [blue]) in the light source 1 and the light source 2 in the light source unit 4. Is provided. It is desirable that the respective laser emission windows are as close as possible so that the illumination light distribution is evenly distributed on the image display element 8.

  FIG. 6 is a diagram illustrating an example of time distribution of the light source On / Off, the polarization state on the image display element, the image display element drive signal, and the pixel shift position in the image display apparatus according to the second embodiment illustrated in FIG. is there. In FIG. 6, light sources 1R, 1G, and 1B indicate three color lasers included in the light source 1, and light sources 2R, 2G, and 2B indicate three color lasers included in the light source 2. The light from the light sources 1R, 1G, and 1B is polarized in the x direction when emitted from the image display element, and the light from the light sources 2R, 2G, and 2B is in the y direction. The light sources 2R, 2G, and 2B take the PS2 position.

  In FIG. 6, each light source sequentially emits light in the order of 1R → 2G → 1B → 2R → 1G → 2B. Therefore, one field is divided into six subfields by a combination of each color and each pixel position. When one field is driven at 60 Hz, the subfield frequency is 360 Hz. When the same color is continuous, color breaks are likely to occur, and when the same pixel shift position is continuous, flicker is likely to occur.Therefore, the adjacent subfields should not have the same type of pixel shift position and color. It is combined.

  As described above, in the second embodiment, the color management is easily performed because the color image is highly refined by the pixel shift technique and the light sources corresponding to the colors are individually provided. Further, light use efficiency can be improved without the need for light shielding by a color filter.

  As Example 3 of the present invention, FIG. 7 shows an example of the configuration of an image display apparatus provided with three color lasers for realizing colorization. As shown in FIG. 7, the image display apparatus according to the third embodiment includes two light source units 4a and 4b, and each of the light source units 4a and 4b has three colors (R [red], G [green], and B). [Blue]) and a combining prism 11 for combining these lasers and emitting them in the same direction.

  In FIG. 7, the synthesis prism 11 can use a synthesis prism used in a commercially available projector. For example, in the light source unit 4a, the light source 1 (G) may be transmitted by being incident on p-polarized light with respect to the combining prism 11, and the light sources 1 (R) and (B) may be reflected by being incident on s-polarized light. In this case, since the polarization direction of the outgoing light is different between G and R, B, a wavelength selective type phase element 9 that selectively rotates the R, B light may be provided on the outgoing side. The light source unit 4b also selectively rotates the light of the light source 2 (G) by the same method, and aligns the polarization direction of each light. After aligning the color polarization directions of the light source units 4a and 4b by the above method, the image display element 8 is illuminated via the PBS 3. Since the operation of each light source is the same as that of the second embodiment, the description thereof is omitted here.

  As Embodiment 4 of the present invention, FIG. 8 shows a configuration example of an image display apparatus including three color lasers for realizing colorization. As shown in FIG. 8, the image display apparatus according to the fourth embodiment includes three light source units (light source unit 14 (R), corresponding to three colors (R [red], G [green], and B [blue]). Light source unit 15 (G), light source unit 16 (B)), and each light source unit 14, 15, 16 includes a laser of the same color and PBS 3 for emitting these lasers in the same direction. . The same PBS 3 as in the above embodiments can be used.

  In FIG. 8, the light emitted from each light source unit is bent by a mirror or the like (not shown), and enters the prism 13 arranged at the subsequent stage. Since the prism 13 has a different refraction angle depending on the wavelength, the incident angle of light from each light source unit may be selected so that the emitted light has the same optical path. A diffraction grating may be used instead of the prism 13. Since the operation of each light source is the same as that of the second embodiment, the description thereof is omitted here.

  4 (Embodiment 1) and FIG. 6 (Embodiment 2) show the case where the light output intensities of the light sources are all the same during the subfield period. FIG. 9A shows an example of gradation expression of the image display element during this subfield period. For example, in the case of 256 gradations, one subfield is divided into 255 times, and the On / Off time is set according to the image signal. More specifically, the division time of 255 is expressed by an 8-bit signal sequence, black (light-off) is expressed by “00000000”, luminance of 1/255 is expressed by “00000001”, and all lighting is expressed by “11111111”. The least significant bit is called LSB (Least Significant Bit). In FIG. 6, when one subfield is set to 2.8 ms (= 360 Hz), the LSB becomes 10.9 μs. Although it is necessary to sufficiently express this LSB as the response of the image display element, it is difficult to achieve this response time in the current performance of the image display element. In other words, the current gradation expression is difficult in performing pixel shift by dividing into subfields.

  As a countermeasure against this problem, in this embodiment, a case where gradation expression is performed by combining laser output modulation will be described with reference to FIG. In FIG. 9B, one subfield is set to 260 division times, and the least significant 2 bits are assigned 4/260 times. In the above example, it is 42.7 μs. If it is this time, it can be sufficiently expressed by the responsiveness of the current image display element. In the least significant bit, the light quantity of the light source is attenuated to ¼ within the time of 42.7 μs, the second bit is attenuated to ½, and the light quantity itself is reduced to achieve gradation expression. Although the laser output intensity may be modulated, a more easily controlled method is to pulse the laser within the LSB period and modulate the pulse width, that is, 10.7 μs (= 42.7 / s) in the least significant bit. The illumination may be performed with a pulse width of 4 μs).

  As described above, there is a problem that a sufficient number of gradations cannot be secured due to restrictions on image display element responsiveness when performing gradation expression by the image display element. In the present embodiment, this is considered as intensity modulation or pulse width of the light source. Since the problem is solved by combining with modulation, it is possible to perform color expression with the conventional number of gradations while performing pixel shift.

  As mentioned above, although each Example of this invention was described, it is not limited to description of each said Example, A various deformation | transformation is possible in the range which does not deviate from the summary.

  The present invention can be applied to general image display devices in addition to stereoscopic display devices.

It is a figure which shows schematic structure of the image display apparatus which concerns on Example 1 of this invention. It is a figure which shows the structure of the birefringent element of the image display apparatus which concerns on Example 1 of this invention. It is a figure which shows the direction and position of a pixel shift of the image display apparatus which concerns on Example 1 of this invention. It is a figure which shows the example of time distribution of On / Off of a light source, the polarization state on an image display element, an image display element drive signal, and a pixel shift position in the image display apparatus which concerns on Example 1 of this invention. It is a figure which shows schematic structure of the image display apparatus which concerns on Example 2 of this invention. It is a figure which shows the example of time distribution of On / Off of a light source, the polarization state on an image display element, an image display element drive signal, and a pixel shift position in the image display apparatus which concerns on Example 2 of this invention. It is a figure which shows schematic structure of the image display apparatus which concerns on Example 3 of this invention. It is a figure which shows schematic structure of the image display apparatus which concerns on Example 4 of this invention. (A) is a figure which concerns on Example 5 of this invention, and is a figure which shows the example of the gradation expression of the image display element in a subfield period in an image display apparatus, (b) is Example 5 of this invention. In connection with this, it is a figure for demonstrating the case where a gradation expression is combined with the output modulation of a laser in an image display apparatus. It is a figure which shows schematic structure of the conventional image display apparatus. It is a figure which shows the structural example of a color wheel.

Explanation of symbols

1, 2, 14, 15, 16 Light source 3 PSB
4, 4a, 4b Light source unit 5 Illumination switching means 6 Birefringence element 7 Projection lens 8 Image display element 9 Phase element 11 Synthetic prism 13 Prism

Claims (10)

An image display element;
A light source unit composed of two light sources for irradiating the image display element with light having polarization directions orthogonal to each other;
A birefringent element provided on the side from which light is emitted from the image display element and having an optical axis in a direction inclined with respect to the output optical axis;
An image display device comprising:   The image display apparatus according to claim 1, wherein light is emitted alternately from each light source of the light source unit.   3. The image display device according to claim 1, wherein a plurality of the light sources correspond to light of three colors or more and are provided.   The image display apparatus according to claim 1, wherein the light source is a laser that emits linearly polarized light.   5. The polarization direction of light rays alternately incident on the image display element is a direction perpendicular to or parallel to a diagonal direction of the pixels in the image display element. 6. Image display device.   5. The polarization direction of light rays alternately incident on the image display element is a direction perpendicular or parallel to a side direction of a pixel in the image display element. 6. Image display device.   The polarization direction of the light beam emitted from the image display element and incident on the birefringent element is parallel to and perpendicular to the plane including the optical axis and the optical axis of the birefringent element. The image display device according to any one of claims 1 to 6.   8. The image display device according to claim 7, wherein the amount of deflection of the parallel light beams by the birefringence element is a half pitch of the image display element pixel array in the deflection direction.   9. The image display device according to claim 1, wherein a display rewrite timing of the image display element is synchronized with a switching timing of a polarization state of the light source.   9. The image display device according to claim 1, wherein the light amount of the light source is modulated in synchronization with a display rewrite timing of the image display element.

Images