Image Projection Device

Abstract

To provide an image projection device with which it is possible to fill a gap between pixels of a projection image by a simple structure.SOLUTION: Provided is an image projection device (1) comprising: a light source (10); an optical modulation device (2) for modulating light emitted from the light source (10) and passing the light modulated in accordance with input image information through from a plurality of pixel aperture parts (PA) partitioned by a lattice-like black matrix part (BM); a projection optical device (5) for projecting an image composed of a plurality of pixel regions corresponding to the pixel aperture parts and the black matrix part and a black matrix corresponding region; and a polarization diffraction grating (6) for separating the light having passed through the pixel aperture parts into a 0-order light and a primary light and located between the optical modulation device (2) and the projection optical device (5), or on the emission plane side of the projection optical device (5), with the 0-order light projected to the pixel regions, with the primary light projected to at least a portion of the black matrix corresponding region.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image projection device, and more particularly to an image projection device for displaying images that includes a polarization grating. [Background technology]

[0002] Conventionally, there is known an image projection device that can modulate light emitted from a light source to form an image according to input image information, and enlarge and project the formed image onto a projection surface such as a screen. This type of image projection device is disclosed in, for example, Patent Document 1.

[0003] The image projection device described in Patent Document 1 includes a spatial light modulation element and a phase diffraction grating element. The spatial light modulation element has a plurality of substantially rectangular pixel regions arranged in a two-dimensional lattice to form a projection image, and a black matrix region covering the spaces between the pixel regions. The phase diffraction grating element is disposed at a predetermined distance from the spatial light modulation element in the direction of the optical axis of the spatial light modulation element. The phase diffraction grating element causes first-order diffracted light from the pixel regions to be incident on a region including a projection point of a core point on the black matrix region corresponding to a corner of a rectangular periodic region that is repeatedly arranged on the spatial light modulation element without gaps and that evenly includes the periphery of the pixel regions.

[0004] According to the image projection device described in Patent Document 1, the first-order diffracted light of the phase diffraction grating element can be incident on an area corresponding to the black matrix on the projection surface, which is thought to reduce the gaps between pixels. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-205636 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the image projection device described in Patent Document 1, it is necessary to precisely form a rectangular phase grating pattern in which square recesses are arranged in a checkerboard pattern on the surface of the phase grating element, which requires complex processing and makes it difficult to suppress manufacturing costs. In addition, generally, light incident on a phase grating element is split into many orders of diffracted light (hereinafter referred to as first order light, second order light, etc.), and thus diffracted light of a large order may enter an adjacent pixel, causing blurring of the image.

[0007] An object of the present invention is to provide an image projection device that has a simple configuration and is capable of filling gaps between pixels of an image projected onto a projection surface, with little risk of bleeding in the image. [Means for solving the problem]

[0008] The first configuration of the present invention is A light source; an optical modulation device that modulates light emitted from the light source, the optical modulation device having a plurality of pixel openings arranged in a two-dimensional matrix shape that transmit the modulated light in accordance with input image information, and a two-dimensional lattice-shaped black matrix portion that partitions adjacent pixel openings and blocks light; a plurality of pixel regions corresponding to the plurality of pixel openings; and the black matrix. Department a projection optical device for projecting an image having a black matrix corresponding area to the projection optical device; a polarization diffraction grating that is disposed on an optical axis (optical path) from the light source to the projection optical device, between the optical modulation device and the projection optical device, or on the emission surface side of the projection optical device, and that separates the light that has passed through the pixel opening into a zeroth order light and a first order light (first order diffracted light); The zero-order light is projected onto the pixel region, and the first-order light is projected onto at least a part of the black matrix corresponding region. It is an image projection device.

[0009] According to the projection device having the above-mentioned configuration, the zero-order light is incident on the projection surface such as a screen at a position corresponding to the pixel opening of the optical modulation device, and the black matrix Department Since first-order light (first-order diffracted light) is incident on the position corresponding to this, it is possible to reduce dark gaps between bright pixels in the projected image (hereinafter referred to as the projected image), thereby providing a smooth projected image.

[0010] In the image projection device, it is preferable that the diffracted light that passes through one pixel opening and is diffracted by the polarization diffraction grating is set so as not to enter the pixel area onto which the zero-order light that passes through an adjacent pixel opening and is then transmitted through the polarization diffraction grating is projected.

[0011] In the image projection device according to the present invention, the polarization diffraction grating does not substantially generate high-order diffracted light (±2nd order light, ±3rd order light, etc.), so that bleeding and blurring of the projected image can be prevented. At that time, the 1st order diffracted light is also set to be incident only on the black matrix corresponding area adjacent to one pixel area formed by the 0th order light, and not to be incident on the adjacent pixel area, so that a smooth and sharp projected image can be provided.

[0012] In the image projection device, The polarization grating is A film made of a liquid crystalline material is provided. The film has an anisotropic structure in which the optical axis of the film rotates continuously in the film plane toward the lattice vector direction, The magnitude of birefringence is uniform within the film plane. It may also be a projection device.

[0013] According to the image projection device having the above configuration, it is possible to reduce the gaps between pixels in the projected image with a simple configuration, and to provide a smooth projected image.

[0014] In the image projection device, The polarization grating is each having the film and the anisotropic structure; 1 bias Optical Diffraction Gratings and 2 bias An optical diffraction grating is provided. The above 1 bias Optical diffraction grating and the above 2 bias The optical diffraction grating may be an image projection device in which two sheets are combined together along the optical axis so that the grating vectors form an angle of 60° to 90° with each other.

[0015] According to the image projection device having the above configuration, the primary light can be incident on multiple positions in the black matrix corresponding area surrounding each pixel area, which reduces the gap between pixels in both the vertical and horizontal directions, providing a smooth projected image. Effect of the Invention

[0016] According to the present invention, it is possible to provide an image projection device that has a simple configuration and can accurately fill in gaps between pixels of a projection image projected onto a projection surface, with little risk of bleeding in the image. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing an image projection device according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a cross-sectional view showing a configuration of an optical modulation device. [Diagram 3] FIG. 2 is a plan view conceptually illustrating a pixel configuration. [Figure 4] 1 is a perspective view showing a polarization diffraction grating included in a projection device according to a first embodiment of the invention. [Diagram 5] This is a crossed Nicol image of a polarizing diffraction grating captured by a polarizing microscope. [Figure 6] FIG. 11 is an exploded perspective view showing a polarization diffraction grating provided in a projection device according to a second embodiment of the invention. [Figure 7] FIG. 11 is an exploded perspective view showing a polarization diffraction grating provided in a projection device according to a third embodiment of the present invention. [Figure 8]1 is a schematic diagram illustrating an image projection device according to an embodiment of the present invention. [Figure 9] 1 is a schematic diagram illustrating an image projection device according to an embodiment of the present invention. [Figure 10A] FIG. 1 is a cross-sectional view conceptually illustrating an example of the configuration of a polarization diffraction grating. [Figure 10B] FIG. 11 is a cross-sectional view conceptually illustrating another example of the configuration of a polarization diffraction grating. [Figure 11] FIG. 2 is a schematic diagram illustrating an example of an optical system used in manufacturing a polarization diffraction grating. [Figure 12] 1 is a schematic diagram for explaining the alignment of liquid crystal molecules by interference exposure of circularly polarized light. FIG. [Figure 13] 3A and 3B are diagrams illustrating how light emitted from the polarization diffraction grating according to the first embodiment is separated when light from a laser pointer is incident on the polarization diffraction grating. [Figure 14A] 1A and 1B are diagrams showing a state in which a projected image is captured by a camera in an image projection device that is laid out with a polarizing diffraction grating, the left diagram showing the projected image, and the right diagram showing a partial enlargement of the projected image. [Figure 14B] FIG. 13 is a diagram showing a state in which a projected image is captured by a camera in an image projection device that is laid out without a polarization diffraction grating, the left side showing the projected image, and the right side showing a partially enlarged view of the projected image. [Figure 15] 13 is a diagram showing how light emitted from a polarization diffraction grating according to a second embodiment is separated when light from a laser pointer is incident on the polarization diffraction grating. FIG. [Figure 16A] 13A and 13B are diagrams showing a state in which a projected image is captured by a camera in a projection device that is laid out with a polarizing diffraction grating, the left diagram showing the projected image, and the right diagram showing a partial enlargement of the projected image. [Figure 16B] FIG. 13 is a diagram showing a state in which a projected image is captured by a camera in a projection device laid out without a polarizing diffraction device, the left side showing the projected image, and the right side showing a partially enlarged view of the projected image. [Figure 17]13A and 13B are diagrams illustrating how light emitted from a polarization diffraction grating according to a third embodiment is separated when light from a laser pointer is incident on the polarization diffraction grating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In conventional projection devices, due to the presence of a black matrix, light may not enter the gaps between pixels (areas corresponding to the black matrix) in the projected image projected onto a projection surface such as a screen, causing the image to not be displayed smoothly.

[0019] The inventors discovered that by placing a polarizing diffraction grating having a unique optical structure on the optical axis (main axis of the optical path) of the optical system of the projection device, between the optical modulation device and the projection optical device, or on the exit surface side of the projection optical device, it is possible to reduce the gaps between pixels caused by the presence of the black matrix portion and provide a smooth projected image with suppressed bleeding.

[0020] [First embodiment] [Outline of the projection device] A projection device 1 according to an exemplary embodiment of the present invention will be described below with reference to FIG. 1. FIG. 1 is a schematic diagram for explaining the configuration of the projection device 1 according to the first embodiment. The projection device 1 according to this embodiment is an image display device that modulates light emitted from a light source 10 to form an image according to input image information, and enlarges and projects the formed image onto a projection surface 100 such as a screen via a projection optical device 5 (for example, a projection lens). One of the features of this image projection device 1 is that it includes a polarization diffraction grating 6 that is arranged on the optical axis (principal axis of the optical path) from the light source 10 between the optical modulation device 2 and the projection optical device 5, or on the exit surface 5a side of the projection optical device 5, i.e., between the projection optical device 5 and the projection surface 100.

[0021] 1, the image projection device 1 of this embodiment includes a light source 10, dichroic mirrors 11 and 12, reflecting mirrors 13, 14, and 15, an optical modulation device 2, a cross dichroic prism 4, and a projection optical device 5. Although not shown in the figure, the image projection device 1 also includes a control unit that controls the operation of the image projection device 1, a storage unit that stores input image information, and a power supply device that supplies power to electronic components that make up the image projection device 1.

[0022] The light source 10 emits light to be incident on the optical modulation device 2. The light source 10 may have various known configurations, and may include, for example, a solid-state light source such as an LD (Laser Diode) or an LED (Light Emitting Diode), and a wavelength conversion device that converts the wavelength of the light emitted from the solid-state light source.

[0023] The light emitted from the light source 10 first enters the first dichroic mirror 11. The red light transmitted through the first dichroic mirror 11 passes through the reflecting mirror 14 and enters the first optical modulation device 2. The green light reflected by the first dichroic mirror 11 and the second dichroic mirror 12 enters the second optical modulation device 2. The blue light reflected by the first dichroic mirror 11 but transmitted through the second dichroic mirror 12 passes through the reflecting mirrors 13 and 15 and enters the third optical modulation device 2. The red light is modulated by the first optical modulation device 2, the green light is modulated by the second optical modulation device 2, and the blue light is modulated by the third optical modulation device 2, and then these three colors of light are combined by the cross dichroic prism 4, which is a combining optical system. The combined light emitted from the cross dichroic prism 4 enters the projection optical device 5.

[0024] The cross dichroic prism 4 forms a colored image by combining the colored lights modulated by the optical modulation devices 2. In this embodiment, one cross dichroic prism 4 is provided as the combining optical system, but instead, the combining optical system may be configured with a plurality of dichroic mirrors.

[0025] The projection optical device 5 enlarges and projects the image incident from the cross dichroic prism 4 onto a projection surface 100 such as a screen. The projection optical device 5 may have various known configurations, and may be, for example, a lens assembly (projection lens) having multiple lenses and a lens barrel that houses the multiple lenses.

[0026] Dichroic mirrors 11-12, reflecting mirrors 13-15, optical modulation device 2, prism 4, projection optical device 5, and polarization diffraction grating 6 described below are arranged at predetermined positions on the optical axis, which is the principal axis of the designed optical path.

[0027] [Configuration of optical modulation device] Fig. 2 is a schematic cross-sectional view showing an exemplary structure of the optical modulation device 2. The first to third optical modulation devices 2 may all have the same structure, so the following description focuses on only one optical modulation device 2. Note that the thickness and width ratios of each component shown in Fig. 2 do not reflect the actual structure.

[0028] The optical modulation device 2 is an active matrix type liquid crystal device having a TFT (Thin Film Transistor) as a switching element, and has a configuration in which a plurality of pixels are arranged in a matrix in a modulation region that modulates incident light.

[0029] 2, the optical modulation device 2 has an element substrate (TFT substrate 20) and an opposing substrate 21 on both sides of a liquid crystal layer LC. The optical modulation device 2 is configured on the premise that light enters from the opposing substrate 21 side, passes through the liquid crystal layer LC, and exits from the element substrate 20 side, as indicated by the arrows. Between the opposing substrate 21 and the liquid crystal layer LC, a black matrix portion BM and a black matrix layer 22 having pixel openings PA are disposed.

[0030] In the following description, the direction from the opposing substrate 21 side toward the element substrate 20 side, i.e., the traveling direction of light passing through the optical modulation device 2, is referred to as the +Z direction, and although not shown in the figure, the direction opposite to the +Z direction is referred to as the -Z direction. Furthermore, two directions that are perpendicular to the +Z direction and perpendicular to each other are referred to as the +X direction and the +Y direction. Although not shown in the figure, the direction opposite to the +X direction is referred to as the -X direction, and the direction opposite to the +Y direction is referred to as the -Y direction. In addition, in this specification, viewing the object from the light incident side (−Z direction side) is referred to as “planar view”.

[0031] The liquid crystal layer LC is formed between the element substrate 20 and the counter substrate 21, and is composed of liquid crystal (liquid crystal molecules) having positive or negative dielectric anisotropy. By changing the alignment state of the liquid crystal molecules by a voltage applied between the counter electrode 21 and a pixel electrode (not shown) included in the element substrate 20, light incident on the optical modulation device 2 from the counter substrate 21 side can be modulated to perform gray scale display. The modulated light passes through the pixel opening PA and is emitted from the element substrate 20 side.

[0032] 3 is a plan view conceptually showing the configuration of the black matrix layer 22. The black matrix layer 22 is provided with a two-dimensional lattice-shaped black matrix portion BM. In detail, the black matrix portion BM is a lattice-shaped light-shielding region made up of an extension portion BMX extending in the +X direction, an extension portion BMY extending in the +Y direction, and an intersection portion BMC of these extension portions BMX and BMY. Rectangular openings surrounded by the black matrix portion BM become pixel openings PA, which define the respective pixels PxA. Light transmitted through the pixel openings PA forms pixel regions in the projected image.

[0033] Although not shown, in addition to the above-mentioned configuration, the optical modulation device 2 may be covered with a light-transmitting film for dust prevention, and may be provided with a microlens array for focusing incident light at positions corresponding to the pixel openings. Department Although the BM has been described as being formed in the black matrix layer 22, it may be provided in the element electrode 20 and / or the counter electrode 21 as a light-shielding region.

[0034] [Polarizing grating] 1 is disposed on the optical path, outside the projection optical device 5, i.e., between the projection optical device 5 and the projection surface 100 (see FIG. 1). The polarization diffraction grating 6 is in the shape of a (for example, rectangular) plate, and is disposed so that the plate surface on which the optical axes described below are distributed faces the -Z direction, and the light emitted from the projection optical device 5 strikes the plate surface.

[0035] FIG. 4 is a conceptual diagram for explaining the distribution of the direction of the optical axis on the plate surface of the polarization diffraction grating 6 according to one embodiment of the present invention. The polarization diffraction grating 6 has an anisotropic structure in which the optical axis rotates continuously toward the direction of the grating vector. That is, the polarization diffraction grating 6 has a grating-like optical structure in which approximately linear parts in which the optical axis is in a certain direction are arranged periodically at equal intervals, and in the parts between them, the optical axis rotates continuously toward the direction of the grating vector of the grating-like structure. The polarization diffraction grating 6 having such an optical structure outputs the incident light as 0th order light and ±1st order light. Note that in this polarization diffraction grating 6, high-order diffracted light is not substantially generated. For example, the intensity of the second order light can be 1.0% or less, more preferably 0.3% or less, of the intensity of the first order light.

[0036] 5 is a crossed Nicol image of the polarizing diffraction grating 6 produced in Example 1, which will be described later, taken by a polarizing microscope. Due to the above-mentioned lattice-like optical structure, the extinction positions (dark portions) appear periodically (in stripes). Since the mutually orthogonal optical axis directions are the extinction positions, the extinction positions in the same optical axis direction appear as alternate dark portions. The portions where the optical axis is rotated with respect to the extinction positions appear bright in the crossed Nicol image.

[0037] The polarization diffraction grating 6 can be realized by orienting a liquid crystal material so that the optical axes of the material in the same direction appear periodically and at equal intervals on a substrate, and the optical axes rotate continuously toward the direction of the lattice vector, and then fixing the orientation (hereinafter, "periodic orientation"). The polarization diffraction grating formed by this method has the same refractive index over the entire area. In other words, there are no areas where the refractive index is discontinuous, so optical problems such as scattering do not occur.

[0038] By disposing the polarization diffraction grating 6 having such a configuration between the dichroic prism 4 and the projection surface 100 on the optical path from the light source 10, the light incident on the polarization diffraction grating 6 from the dichroic prism 4 can be separated into 0th order light and ±1st order light. By appropriately setting the position and diffraction angle of this polarization diffraction grating 6, the 0th order light is directed to the pixel region corresponding to pixel PxA in the projected image, and the ±1st order light is directed to the black matrix adjacent to this pixel region. correspondence It is possible to make ±1st order light incident on the pixel regions, thereby filling in the gaps between pixel regions of the projected image and obtaining a seamless projected image.

[0039] In order to reduce the dark areas in the black matrix corresponding areas, the light (pixel light) that has passed through two adjacent pixel apertures PA should be diffracted by the polarization diffraction grating 6 and incident on the black matrix corresponding areas. correspondence The pixel light may be diffracted so that the light is incident on only half the width of the region (the region corresponding to the extensions BMX and BMY). In the polarization diffraction grating 6, the diffraction angle θ is expressed by the following formula, where λ is the wavelength of the light to be diffracted and d is the grating pitch. θ=a sin(λ / d) Therefore, the diffraction angle can be adjusted by appropriately setting the wavelength λ of the light used and the pitch d of the polarization diffraction grating.

[0040] In the above-mentioned polarization diffraction grating 6, high-order diffracted light such as second-order and third-order light does not occur. Therefore, light transmitted through an adjacent pixel opening PA does not enter as high-order diffracted light into one pixel region formed by zero-order light transmitted through one pixel opening PA of the light modulation device 2 and then transmitted through the polarization diffraction grating 6. Therefore, by using the above-mentioned polarization diffraction grating 6, it is possible to suppress the occurrence of bleeding and blurring in the projected image. Furthermore, it is preferable that the position at which the polarization diffraction grating 6 is disposed and the diffraction angle are set so that the light transmitted through one pixel opening PA to form one pixel region does not enter even the first-order light into the adjacent pixel region. This makes it possible to obtain a sharper projected image.

[0041] When the size of pixel PxA in the optical modulation element 2 is sufficiently larger than the width of the black matrix portion BM (width of BMX, BMY), the polarization diffraction grating 6 may be one that eliminates zero-order light. However, when the size of pixel PxA is equal to or smaller than the width of the black matrix portion BM, it is preferable that the magnitude of anisotropy (retardation) of the polarization diffraction grating is greater than λ / 2 or less than λ / 2 in order to transmit zero-order light.

[0042] As shown in FIG. 3, the pixel PxA of the optical modulation element 2 is surrounded by a lattice-shaped black matrix portion BM. Therefore, in order to prevent the black matrix corresponding area from becoming dark in the projected image and to obtain a smooth projected image, it is preferable to extract diffracted light in a plurality of directions. This can be achieved by using two overlapping polarization diffraction gratings 6. In this case, in order to disperse the direction of the diffracted light, it is preferable that the angle between the grating vectors of the two polarization diffraction gratings 6 is 60° to 90°. In the following, the case of an angle of 90° will be described as the second embodiment, and the case of an angle of 60° will be described as the third embodiment.

[0043] [Second embodiment] An image projection device 1 according to a second embodiment of the present invention will be briefly described with reference to Fig. 1 and Fig. 6. The second embodiment differs from the first embodiment in that the polarization grating 6 is formed by combining a first polarization grating 6F and a second diffraction grating 6G in two layers along the optical axis.

[0044] Both the first polarization grating 6F and the second polarization grating 6G have the same configuration as the polarization grating 6 according to the first embodiment. The first polarization grating 6F and the second polarization grating 6G are overlapped with the film made of a liquid crystal material facing the -Z direction. However, the first polarization grating 6F and the second polarization grating 6G are overlapped with their grating vectors at an angle of 90°, as shown in FIG.

[0045] According to such a polarization grating 6, the light incident on the first polarization grating 6F is separated into −1st order light, 0th order light, and +1st order light and then emitted. Then, of the light of the multiple orders incident on the second polarization grating 6G, the −1st order light from the first polarization grating 6F is separated into 0th order light and −1st order light, the 0th order light from the first polarization grating 6F is separated into −1st order light, 0th order light, and +1st order light, and the 1st order light from the first polarization grating 6F is separated into 0th order light and +1st order light and then emitted. In this way, according to the polarization grating 6 according to the second embodiment, the incident light can be separated into seven diffracted lights, with six 1st order lights distributed around the 0th order light. By using such a polarization grating 6, it is possible to fill the gaps in the +X direction and the +Y direction of the pixels, and a more seamless projection image can be obtained.

[0046] [Third embodiment] An image projection device 1 according to a third embodiment of the present invention will be briefly described with reference to Fig. 1 and Fig. 7. The third embodiment differs from the first embodiment in that the polarization grating 6 is formed by combining a first polarization grating 6F and a third diffraction grating 6H in two layers along the optical axis.

[0047] The configuration of the first polarization grating 6F is the same as that shown in the second embodiment. The third polarization grating 6H is different from the second polarization grating 6G of the second embodiment in that the grating vector direction of the third polarization grating 6H is formed to form an angle of 60° with respect to the grating vector direction of the first polarization grating 6F. The first polarization grating 6F and the third polarization grating 6H are superimposed with their grating vectors forming an angle of 60° as shown in FIG.

[0048] According to such a polarization grating 6, the light incident on the first polarization grating 6F is separated into -1st order light, 0th order light, and +1st order light and then emitted. Then, of the light of the multiple orders incident on the third polarization grating 6H, the -1st order light from the first polarization grating 6F is separated into 0th order light and -1st order light, the 0th order light from the first polarization grating 6F is separated into -1st order light, 0th order light, and +1st order light, and the 1st order light from the first polarization grating 6F is separated into 0th order light and +1st order light and then emitted. In this way, according to the polarization grating 6 according to the third embodiment, the incident light can be separated into seven light beams, with six 1st order lights distributed around the 0th order light. Moreover, according to this embodiment, the six 1st order lights arranged around the 0th order light can be arranged at approximately equal intervals in the circumferential direction. By using such a polarization grating 6, it is possible to separate the black matrix adjacent to the corresponding pixel region. correspondence The black matrix area B The primary light can be incident not only on the area corresponding to the extension parts BMX, BMY of M, but also on the area corresponding to the intersection parts BMC of these extension parts BMX, BMY (the intersection parts BMC of the four corners surrounding the pixel), making it easier to obtain a seamless projected image.

[0049] The image projection device 1 of the present invention is not limited to the above embodiment. For example, in Fig. 1, the polarizing diffraction element 6 is disposed on the exit surface side of the projection optical device 5, i.e., between the projection optical device and the projected surface 100, but it may be disposed on the entrance surface side of the projection optical device 5, i.e., between the projection optical device 5 and the cross dichroic prism 4.

[0050] In the image projection device shown in the above embodiment, dichroic mirrors 11-12 and reflecting mirrors 13-15 are provided as a color separation device, but this layout is merely an example, and other layouts may be adopted.

[0051] The structure of the optical modulation device 2 shown in the above embodiment is merely an example, and the optical modulation device can adopt various known structures as long as it has a pixel opening and a black matrix portion.

[0052] In the above embodiment, an image projection device in which the optical modulation device 2 is a transmissive liquid crystal type has been described as an example, but the configuration of the image projection device is not limited to this. Alternatively, the optical modulation device can be a reflective liquid crystal type, for example, an LCOS-SLM (Liquid Crystal On Silicon-Spatial Light Modulator) type, or a DLP (digital light processing) type.

[0053] 8 shows the configuration of the image projection device 1 when the optical modulation device is of the LCOS type. Light from the light source 10 is separated into red light, green light, and blue light by dichroic mirrors 72 and 74 and a total reflection mirror 73. The light of each color is reflected and modulated by a polarizing beam splitter 71. The modulated light of each color is synthesized by a dichroic prism 4 to form a colored image, which is enlarged by a projection optical device 5 and projected onto a projection surface 100. Even in the case of such a configuration, for example, a polarizing diffraction grating 6 may be provided between the dichroic prism 4 and the projection surface 100 on the optical axis from the light source 10.

[0054] 9 shows the configuration of the image projection device 1 when the optical modulation device is of the DLP type. Light from the light source 10 is incident on a color filter 81. The light emitted from the color filter 81 is transmitted through a relay lens unit 82 and then incident on a digital micromirror device 83. In the digital micromirror device 83, mirrors are arranged for each pixel, and only light from the corresponding mirror is irradiated toward a projection optical device (projection lens) 85, and the other light is absorbed by a light absorbing plate 84. The light incident on the projection optical device 85 is projected onto a projection surface 100. Even in the case of such a configuration, for example, a polarizing diffraction grating 6 may be provided between the projection optical device 85 and the projection surface 100 on the optical axis from the light source 10.

[0055] The image projection device 1 may be a short focal type that projects an image onto the projection surface 100 from a short distance, or a non-short focal type. When the polarization diffraction grating 6 is disposed on the exit surface side of the projection optical device 5, 85, the polarization diffraction grating 6 may be attached to a commercially available image projection device 1 using something like an adapter.

[0056] [Method of manufacturing polarization grating] The polarization diffraction grating 6 having the optical structure used in the image projection device 1 described above can be manufactured, for example, by the following method. [Method 1] A method for producing a polarization diffraction grating with an optically anisotropic structure in which the optical axis rotates continuously in the direction of the lattice vector by coating a liquid crystalline material with photo-alignment on a substrate, irradiating the coating with right-handed circularly polarized light and left-handed circularly polarized light, and fixing the alignment produced by the interference exposure of the two light beams. [Method 2] A method for producing a polarized diffraction grating with an optically anisotropic structure in which the optical axis rotates continuously in the direction of the lattice vector by coating a liquid crystalline material with photo-alignment properties on a substrate, irradiating the coating with right-handed circularly polarized light and left-handed circularly polarized light, and forming an alignment film by interference exposure of the two beams of light, coating a polymerizable crystalline composition or the like on the alignment film and orienting it according to the alignment of the alignment film, and fixing the orientation.

[0057] 10A and 10B are cross-sectional views of a polarization grating 6 manufactured according to the above method. Note that the thicknesses of the layers in these figures do not limit the actual thickness ratio. When manufactured by method 1, the polarization grating 6 has a layer 6b in which a photo-alignable liquid crystal material exhibits periodic alignment formed on a substrate 6a, as shown in FIG. 10A. When manufactured by method 2, an alignment film 6c in which a photo-alignable liquid crystal material exhibits periodic alignment is formed on the substrate 6a, as shown in FIG. 10B, and a layer 6d in which a polymerizable liquid crystal composition exhibits periodic alignment according to the alignment of the alignment film 6c is formed thereon.

[0058] The polarization grating 6 may be used with the substrate 6a. In this case, the substrate 6a may be an optically isotropic body, or may be another optical member to be combined with the polarization grating 6. If necessary, the substrate 6a may be peeled off and used as the polarization grating 6. The thickness of the polarization grating 6 of the present invention is not particularly limited, but it is easy to make it thin, and even if the film thickness on the substrate 6a is 1 mm or less, preferably 50 μm or less, it can be used as the polarization grating 6. For example, in the polarization grating 6 shown in FIG. 10A, the layer 6b may have a thickness of about 1 to 30 μm, and in the polarization grating 6 shown in FIG. 10B, the layer 6c may have a thickness of about 0.06 to 10 μm, and the layer 6d may have a thickness of about 1 to 30 μm. The thickness of the substrate 6a is not particularly limited, and may be appropriately selected depending on the application.

[0059] [Interference exposure device] Fig. 11 is a top view showing the optical system of an apparatus that can be used for interference exposure in the above manufacturing method. M1 to M4 in Fig. 11 are total reflection mirrors provided for adjusting the direction of the optical path, and for simplification, their description is omitted. Light emitted from a light source 110 is split by a polarizing beam splitter 120 into a p-wave that passes through a first optical path P1 and an s-wave that passes through a second optical path P2.

[0060] The p-wave passes through a half-wave plate 130 and a quarter-wave plate 140 arranged on a first optical path P1 and is converted into left-handed circularly polarized light, which is then magnified by a magnifying optical system 150 and irradiated onto the sample S. The s-wave passes through a half-wave plate 160 and a quarter-wave plate 170 arranged on a second optical path P2 and is converted into right-handed circularly polarized light, which is then magnified by a magnifying optical system 180 and irradiated onto the sample S. In response to the interference exposure of the left-handed circularly polarized light LCP and the right-handed circularly polarized light RCP, the liquid crystal molecules exhibiting photo-alignment are periodically arranged while changing their orientation as shown diagrammatically in FIG. 12, and the optical characteristics of the polarization diffraction grating 6 of the present invention are obtained.

[0061] As the light source 110, for example, an ultraviolet laser light source may be used. The dimensions of the optical system are not particularly limited. By appropriately adjusting the optical system, it is possible to adjust the interval between the interference fringes formed by the interference exposure and to adjust the magnitude of the grating vector in the polarization diffraction grating. For example, when performing the interference exposure, the magnitude of the grating vector can be changed by changing the distance between the total reflection mirrors M3, M4 and the sample S.

[0062] In addition, other methods can be used as long as they can provide a periodic alignment to a liquid crystal material exhibiting photoalignment. For example, the layer 6b shown in Fig. 10A or the layer 6c shown in Fig. 10B may be formed by scanning a linearly polarized laser beam while changing the polarization direction, or by exposing the linearly polarized laser beam through a mask while changing the polarization direction and the mask position.

[0063] [Liquid crystal materials exhibiting photo-alignment] As the liquid crystalline material exhibiting photoalignment property used in the above manufacturing method, for example, a liquid crystalline material that contains a photosensitive group in at least a part of the side chain and is composed of at least a polymer having a side chain represented by any one of the chemical formulas 1 to 3 below can be used. [ka] [ka] [ka] In each of the chemical formulas 1 and 2, n represents an integer of 1 to 12, and m represents an integer of 1 to 12, respectively; X and Y represent none, -COO, -OCO-, -N=N-, -C=C-, or -CH-, respectively; W1 and W2 represent a cinnamoyloxy group, a chalcone group, a cinnamylidene group, a biphenylacryloyloxy group, a furylacryloyloxy group, a naphthylacryloyloxy group, or a derivative thereof, or represent -H, -OH, or -CN; and in the chemical formula 3, s represents 0 or 1, t represents an integer of 1 to 3, and R represents H, an alkyl group, an alkyloxy group, or a halogen.

[0064] When the above liquid crystal material is used, the side chains having photosensitive groups are aligned by periodically changing the alignment direction due to interference exposure of left-handed circularly polarized LCP and right-handed circularly polarized RCP, as shown in Figure 12. Even if the liquid crystal material contains side chains without photosensitive groups, these will be aligned according to the aligned side chains in the vicinity during the heating and cooling process, and the periodic alignment will be fixed in the sample. The specific process can be performed under the following conditions.

[0065] [Paint film formation] A liquid crystalline polymer formed from monomer units having side chains represented by the above chemical formulas 1 to 3, and optionally a low molecular weight compound and other components (such as a polymerization catalyst) are added to the above liquid crystalline polymer, and these are dissolved in a suitable solvent to prepare a coating liquid, which is then coated on a substrate, and the solvent is removed to form a liquid crystalline polymer layer on the substrate.

[0066] Examples of the solvent include dioxane, dichloroethane, cyclohexanone, toluene, tetrahydrofuran, o-dichlorobenzene, methyl ethyl ketone, and methyl isobutyl ketone. These solvents may be used alone or in combination.

[0067] The support may be a glass substrate or a variety of polymer films, including polyester films such as polyethylene terephthalate, cellulose films such as diacetyl cellulose and triacetyl cellulose, polycarbonate films such as bisphenol A-carbonate copolymers, linear or branched polyolefin films such as polyethylene, polypropylene, and ethylene-propylene copolymers, polyamide films, imide polymer films, and sulfone polymer films.

[0068] [Interference exposure] The coating solution is applied onto a support and dried to the extent that the solvent is removed. After that, a periodic orientation layer can be formed by imaging left-handed circularly polarized light and right-handed circularly polarized light onto the coating film using, for example, the device described in Figure 11.

[0069] The interference exposure may be carried out during drying (before complete drying). After the interference exposure, the sample is preferably heated to 80 to 130° C., preferably 100 to 120° C., and then cooled.

[0070] (Formation of periodic alignment layers using polymerizable liquid crystal materials) In some cases, the liquid crystal material having photo-alignment properties represented by the above chemical formulas 1 to 3 may be exposed to interference light of left-handed circularly polarized light and right-handed circularly polarized light to induce periodic alignment, and then this may be used as an underlying alignment film (layer 6c in FIG. 10B) to form a periodic alignment layer (layer 6d in FIG. 10B) made of a polymerizable liquid crystal material thereon. In the description of the present invention, the polymerizable liquid crystal material does not include a liquid crystal material having photo-alignment properties by itself. This periodic alignment layer can be formed by dissolving the polymerizable liquid crystal material in a solvent, applying the solution onto the alignment film, drying the solution after application, and performing a heat treatment to induce the alignment of the polymerizable liquid crystal material, and then irradiating the solution with non-polarized ultraviolet light to fix the alignment.

[0071] [Polymerizable liquid crystal material] In the present invention, the polymerizable liquid crystal material to be aligned on the alignment film may be a liquid crystal polymer or a liquid crystal monomer. The polymerizable liquid crystal material may be a liquid crystal polymer or a liquid crystal monomer in which a crosslinking structure is introduced to a degree that does not impair liquid crystallinity by a crosslinking agent such as an isocyanate material or an epoxy material. In addition, the following bifunctional low molecular weight material may be added as a low molecular weight material and applied to align the polymerizable liquid crystal material, and then polymerized to contain a crosslinkable polymer. If necessary, a photopolymerization initiator, a thermal polymerization initiator, or a sensitizer may be mixed. By aligning such a liquid crystal material on the alignment film and fixing the alignment, an optically anisotropic layer having the characteristics of a polarization diffraction grating can be formed on the alignment film.

[0072] Examples of the polymerizable liquid crystal include liquid crystal compounds having a Schiff base type, biphenyl type, terphenyl type, ester type, thioester type, stilbene type, tolan type, azoxy type, azo type, phenylcyclohexane type, pyrimidine type, cyclohexylcyclohexane type, trimesic acid type, triphenylene type, truxene type, phthalocyanine type, and porphyrin type molecular skeleton, and mixtures of these compounds, and include those that can be aligned and fixed by means of thermal crosslinking or photocrosslinking in a liquid crystal state or in a state cooled below the liquid crystal transition temperature by introducing a crosslinkable group or blending an appropriate crosslinking agent. As the polymerizable liquid crystal, it is preferable to use a compound that exhibits a nematic liquid crystal phase.

[0073] The polymerizable liquid crystal may be a liquid crystal polymer that can be oriented and fixed by means of thermal crosslinking, photocrosslinking, or the like in a liquid crystal state or in a state cooled below the liquid crystal transition temperature by introducing a crosslinkable group or blending an appropriate crosslinking agent, and is not particularly limited as long as it has a unit composed of a mesogen-forming group. The unit may be in the main chain of the liquid crystal polymer or in the side chain. Examples of main chain liquid crystal polymers include polyesters, polyamides, polycarbonates, polyimides, polyurethanes, polybenzimidazoles, polybenzamides, and the like. Examples of the liquid crystal polymer include polybenzoxazole-based, polybenzothiazole-based, polyazomethine-based, polyesteramide-based, polyestercarbonate-based, and polyesterimide-based liquid crystal polymers, and mixtures thereof. Examples of the side-chain liquid crystal polymer include polyacrylate-based, polymethacrylate-based, polyvinyl-based, polysiloxane-based, polyether-based, and polymalonate-based liquid crystal polymers having a linear or cyclic skeletal chain structure to which a mesogen group is bonded as a side chain, and mixtures thereof. As the liquid crystal polymer, it is preferable to use a polymer that exhibits a nematic liquid crystal phase.

[0074] Examples of the crosslinkable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, an oxetanyl group, etc. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

[0075] As the polymerizable liquid crystal, a commercially available liquid crystal compound can be used. For example, LC242 manufactured by BASF may be used. These liquid crystal compounds are less expensive than the liquid crystal compounds having photo-alignment properties as shown in Chemical Formulas 1 to 3, and therefore the cost of manufacturing the polarization diffraction grating (and thus the manufacturing cost of the image projection device) can be reduced compared to the case where the polarization diffraction grating is formed using only the liquid crystal compound having photo-alignment properties.

[0076] As the photopolymerization initiator, commercially available photopolymerization initiators such as Irgacure 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369 (all manufactured by Chiba Japan Co., Ltd.), Seikuol BZ, Seikuol Z, Seikuol BEE (all manufactured by Seiko Chemical Co., Ltd.), Kayacure BP100 (manufactured by Nippon Kayaku Co., Ltd.), Kayacure UVI-6992 (manufactured by Dow), Adeka Optomer SP-152 or Adeka Optomer SP-170 (all manufactured by ADEKA Co., Ltd.), TAZ-A, TAZ-PP (manufactured by Nippon SiberHegner Co., Ltd.), and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.) can also be used.

[0077] Examples of the thermal polymerization initiator include azo compounds such as azobisisobutyronitrile; and peroxides such as hydrogen peroxide, persulfates, and benzoyl peroxide. The content of the polymerization initiator is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound (or polymerizable liquid crystal polymer). Within the above range, the polymerizable liquid crystal compound can be polymerized without disturbing the alignment.

[0078] When a photopolymerization initiator is used as the polymerization initiator, a photosensitizer may be used in combination. Examples of the photosensitizer include xanthone compounds such as xanthone and thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and an alkoxy group-containing anthracene (e.g., dibutoxyanthracene, etc.); phenothiazine; rubrene, etc.

[0079] If necessary, a photosensitive compound may be added to the polymerizable liquid crystal material used to form the alignment layer in an amount that does not disturb the liquid crystallinity of the polymerizable liquid crystal material. In this case, it is preferable to use a photosensitive group having the same or similar chemical structure as the photosensitive group of the liquid crystal material having the photosensitive group that forms the underlying alignment film. For example, about 0.5 to 10 parts by mass of the liquid crystal material having photoalignment properties represented by the above chemical formulas 1 to 3 may be mixed with 100 parts by mass of the polymerizable liquid crystal compound (or polymerizable liquid crystal polymer).

[0080] [Formation of alignment film] The alignment film can be formed in the same manner as the process for forming a periodic alignment layer using the liquid crystal material having photoalignment. That is, a liquid crystal polymer formed from a monomer unit having a side chain represented by the above chemical formulas 1 to 3, and if necessary, a low molecular weight compound and other components (such as a polymerization catalyst) are added to the above liquid crystal polymer, and these are dissolved in an appropriate solvent to prepare a coating liquid, which is then coated on a substrate, and the solvent is removed to form a liquid crystal polymer layer on the substrate. Here, the above-mentioned solvent and substrate can be used. Next, the coating film is exposed to interference light with left-handed circularly polarized light and right-handed circularly polarized light using, for example, the device described in FIG. 11, to impart periodic alignment to the coating film. After interference exposure, the sample may be heated to 80 to 130° C., preferably 100 to 120° C., and then cooled. However, the heating and cooling of the sample may be performed after the polymerizable liquid crystal material is applied.

[0081] [Formation of polymerizable liquid crystal material layer] After forming an alignment film on a substrate, the above-mentioned polymerizable liquid crystal material is applied onto the alignment film and dried, whereby alignment is induced in the polymerizable liquid crystal material according to the alignment of the underlying alignment film.

[0082] [Non-polarized ultraviolet light] It is preferable to apply a polymerizable liquid crystal material onto the alignment film, align it according to the alignment of the alignment film, and then irradiate it with non-polarized ultraviolet light. When irradiated with non-polarized ultraviolet light, the polymerizable groups in the polymerizable liquid crystal material react to fix the alignment, forming a stable periodic alignment layer and fixing the alignment of the alignment film. In addition, at the interface between the alignment film and the polymerizable liquid crystal material layer, a photoreaction occurs between the photosensitive groups of the liquid crystal material forming the alignment film and the photosensitive groups contained in the polymerizable liquid crystal material, which is thought to contribute to the high adhesion between the two layers.

[0083] In this manner, the alignment film is utilized to align the polymerizable liquid crystal material directly laminated thereon, thereby making it possible to form the polarization diffraction grating 6 of the present invention. EXAMPLES

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0085] (Monomer 1) 4-(6-hydroxyhexyloxy)cinnamic acid was synthesized by heating p-coumaric acid and 6-chloro-1-hexanol under alkaline conditions. A large excess of methacrylic acid was added to this product in the presence of p-toluenesulfonic acid to cause an esterification reaction, synthesizing monomer 1 shown in the following chemical formula.

[0086] [ka]

[0087] (Monomer 2) 4-Hydroxybenzoic acid and 6-chloro-1-hexanol were heated under alkaline conditions to synthesize 4-(6-hydroxyhexyloxy)benzoic acid. Next, a large excess of methacrylic acid was added to this product in the presence of p-toluenesulfonic acid to cause an esterification reaction, synthesizing monomer 2 shown in the following chemical formula.

[0088] [ka]

[0089] (Copolymer 1) Monomer 1 and monomer 2 were dissolved in dioxane so that the molar ratio of monomer 1 to monomer 2 was monomer 1:monomer 2=3:7, and AIBN (azobisisobutyronitrile) was added as a reaction initiator. The copolymer was polymerized at 70°C for 24 hours to obtain copolymer 1. This copolymer 1 exhibited liquid crystallinity.

[0090] Example 1 Copolymer 1 and cinnamic acid were dissolved in tetrahydrofuran (THF) in a weight ratio of 95:5 to prepare a solution. This solution was applied to a cover glass substrate to a thickness of 3 μm using a spin coater and dried at 25°C. The dried coating film was subjected to interference exposure (irradiation dose 200 mJ / cm) using the interference exposure optical system shown in Figure 11, in which 360 nm ultraviolet laser light emitted from a DPSS laser used as a light source was used as left-handed circularly polarized light and right-handed circularly polarized light. 2 ) was then heated at 130°C for 3 minutes and cooled to room temperature to induce orientation. This orientation occurs when axially selective photoreacted side chains are generated in the coating film in accordance with the polarization direction of the light exposed to each region by interference exposure, and the unreacted side chains are aligned along the reacted side chains due to subsequent molecular motion caused by heating. The coating film thus obtained is oriented such that the optical axis rotates continuously toward the grating vector direction. By this method, the polarizing diffraction grating according to the present invention was obtained.

[0091] The anisotropy of the polarization diffraction grating was measured by the Senarmont method using a polarizing microscope. The grating pitch was determined by measuring the grating periodic width under crossed Nicols. The diffraction angle was calculated by measuring the diffraction width of the zeroth order light and the ±1st order light at a specific distance from the polarization diffraction grating, as the angle between the zeroth order light and the ±1st order light, and using trigonometric functions. The ratio of the diffraction intensities was calculated by measuring the zeroth order light and the ±1st order light with a power meter.

[0092] When the optical characteristics of the polarization diffraction grating obtained in Example 1 were examined, the magnitude of anisotropy was about 130 nm at 550 nm, the grating pitch was 450 μm, and the diffraction angle at 532 nm was 0.07°. In addition, the ratio of the diffraction intensity at 532 nm was about −1st order light: 0th order light: +1st order light = 1:2:1. Note that FIG. 13 shows a photograph of the light emitted from the polarization diffraction grating obtained in Example 1 when light from a single laser pointer was incident on the polarization diffraction grating. As shown in FIG. 13, in the light emitted from the polarization diffraction grating, high-order diffracted light (±2nd order light, ±3rd order light) was not visible.

[0093] Example 2 In order to evaluate whether or not the polarization diffraction grating 6 according to the first embodiment has the effect of filling the gaps between pixels in a projected image when mounted on an image projection device, a polarization diffraction grating (diffraction angle 0.058°) was arranged in an image projection device (short focal type) as shown in Fig. 1 (Layout 1). For comparison, an image projection device (short focal type) was prepared in which the components were arranged in the same manner as in Fig. 1 except that the polarization diffraction grating was not arranged (Layout 2).

[0094] In each of layouts 1 and 2, the same input image information was input to the image projection device, and the projection image projected onto the projection surface was captured by a camera. In addition, a part of the region of this projection image was enlarged to the same magnification and captured by the camera. FIG. 14A shows the projection image captured by the camera in the image projection device of layout 1, with the left being a photograph of the projection image and the right being a photograph of a partially enlarged projection image. Meanwhile, FIG. 14B shows the projection image captured by the camera in the image projection device of layout 2, with the left being a photograph of the projection image and the right being a photograph of a partially enlarged projection image.

[0095] Comparing the right side of Fig. 14A with the right side of Fig. 14B, it can be seen that the gaps between pixels are less noticeable when a polarization diffraction grating is provided compared to when no polarization diffraction grating is provided. That is, in the right side of Fig. 14A, the gaps between pixels are filled compared to the right side of Fig. 14B, and no bleeding or blurring between pixels was observed. This is because the ±1st order light emitted from the polarization diffraction grating is reflected by the black matrix adjacent to the corresponding pixel in the projected image. vs. This is thought to be because the light was only irradiated onto the target area. In this way, it was found that by arranging a polarizing diffraction grating in an image projection device, it is possible to reduce the gaps between pixels, resulting in a smooth (seamless) projected image.

[0096] Example 3 A first polarization grating 6F and a second polarization grating 6G were produced in the same manner as in Example 1, and the first polarization grating 6F and the second polarization grating 6G were overlapped as shown in Fig. 6 to obtain a polarization grating according to the second embodiment. Note that Fig. 15 shows a photograph of the light emitted from the polarization grating when light from a single laser pointer was incident on the (two-layered) polarization grating 6 obtained in Example 3.

[0097] Example 4 In order to evaluate whether or not the polarization diffraction grating according to the second embodiment has the effect of filling the gaps between pixels in a projected image when mounted on an image projection device, a polarization diffraction grating (0.029°) was arranged (Layout 1) in a (non-short focal type) image projection device as shown in Fig. 1. For comparison, a (non-short focal type) image projection device was prepared (Layout 2) in which the components were arranged in the same manner as in Fig. 1, except that the polarization diffraction grating was not arranged.

[0098] In each of layouts 1 and 2, the same input image information was input to the image projection device, and the projection image projected onto the projection surface was captured by a camera. A part of the region of this projection image was enlarged to the same magnification and captured by the camera. Fig. 16A shows the projection image captured by the camera in the image projection device of layout 1, with the left being a photograph of the projection image and the right being a photograph of a partially enlarged projection image. Meanwhile, Fig. 16B shows the projection image captured by the camera in the image projection device of layout 2, with the left being a photograph of the projection image and the right being a photograph of a partially enlarged projection image.

[0099] Comparing the right side of FIG. 16A with the right side of FIG. 16B, it can be seen that the gaps between pixels are much less noticeable when a polarization grating is provided than when a polarization grating is not provided. This is because the first-order light emitted from the polarization grating is reflected by the black matrix adjacent to the corresponding pixel in the projected image. vs. This is thought to be because only the reaction area was irradiated.

[0100] As shown in Fig. 15, the polarization grating of this embodiment was able to separate the incident light into seven diffracted lights, with the zeroth-order light at the center and six first-order lights distributed around it. When this polarization grating was applied to an image projection device, it was possible to fill gaps in both the row and column directions of pixels, resulting in a more seamless projected image.

[0101] Example 5 The first polarization grating 6F and the third polarization grating 6H were produced in the same manner as in Example 1, and the first polarization grating 6F and the third polarization grating 6H were overlapped as shown in Fig. 7 to obtain the polarization grating according to the third embodiment. Note that Fig. 17 shows a photograph of the light emitted from the polarization grating when light from a single laser pointer was incident on the (two-layered) polarization grating obtained in Example 4.

[0102] As shown in Fig. 17, the polarization grating of this embodiment can separate the incident light into seven light beams, with the zeroth-order light at the center and six first-order lights distributed around it. Moreover, this embodiment can arrange the six first-order lights around the zeroth-order light at approximately equal intervals in the circumferential direction. If such a polarization grating is applied to an image projection device, it is believed that gaps in both the row and column directions of pixels can be filled, resulting in a more seamless projected image.

[0103] Considering the difference between Example 5 and Examples 3 and 4, in Example 5, the black matrix adjacent to the corresponding pixel correspondence Among the areas, black matrix corresponding to the extension parts (BMX, BMY) correspondence It is presumed that ±1st order light can be made incident not only on the area but also on the area corresponding to the intersections of these extensions (the intersections BMC at the four corners surrounding the pixel), making it easier to obtain an even more seamless projected image than in Example 4.

[0104] The structure of the optical modulation device 2 shown in the above embodiment is merely an example, and the optical modulation device can adopt various known structures as long as it has a pixel opening and a black matrix portion.

[0105] Although the embodiment for carrying out the present invention has been described above, the embodiment disclosed herein is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0106] 1 Image projection device 2. Optical Modulation Device 5 Projection optical device 6 Polarization Grating 6F 1st Polarization Grating 6G 2nd Polarization Grating 6H 3rd Polarization Grating 10 light source LC liquid crystal layer PA Pixel Aperture Department BM Black Matrix 100 Projected surface

Claims

1. A light source; an optical modulation device that modulates light emitted from the light source, the optical modulation device having a plurality of pixel openings arranged in a two-dimensional matrix shape that transmit the modulated light in accordance with input image information, and a two-dimensional lattice-shaped black matrix portion that partitions adjacent pixel openings and blocks light; a projection optical device that projects an image including a plurality of pixel regions corresponding to the plurality of pixel openings and a black matrix corresponding region corresponding to the black matrix portion; a polarization diffraction grating that is disposed on an optical axis from the light source to the projection optical device, between the optical modulation device and the projection optical device, or on an exit surface side of the projection optical device, and that separates the light that has passed through the pixel opening into a zero-order light and a first-order light; The zero-order light is projected onto the pixel region, and the first-order light is projected onto at least a part of the black matrix corresponding region. Image projection device.

2. 2. The image projection device according to claim 1, The diffracted light transmitted through one of the pixel openings and diffracted by the polarization diffraction grating is set not to be incident on a pixel region onto which the zero-order light transmitted through an adjacent pixel opening and transmitted through the polarization diffraction grating is projected. Image projection device.

3. 3. The image projection device according to claim 1, The polarization grating is A film made of a liquid crystalline material is provided. The film has an anisotropic structure in which the optical axis of the film rotates continuously in the film plane toward the lattice vector direction, The magnitude of birefringence is uniform within the film plane. Image projection device.

4. 4. The image projection device according to claim 3, The polarization grating is a first polarization grating and a second polarization grating, each having the film and the anisotropic structure; The first and second polarization gratings are combined in two layers along the optical axis such that the grating vectors form an angle of 60° to 90° with each other. Projection device.

Images