Image display device and image display unit

Abstract

An image display device according to an embodiment of the present technology is provided with a light emitting unit and a polarization conversion element. The light emitting unit emits image light. The polarization conversion element has an incident surface, converts the polarization state of the image light incident on the incident surface, and emits the converted light as non-polarized state image light, and is configured so that the conversion characteristics of the polarization state are non-uniform in the incident surface. As a result, the image light can be fully depolarized and a high-quality image can be displayed. In addition, non-uniform polarization and speckle can be reduced.

Description

Technical Field

[0001] The present technology relates to an image display device and an image display unit. Background Art

[0002] In the past, image display devices such as projectors have been widely used. In the projection device described in Patent Document 1, a polarization conversion unit capable of uniformly and omnidirectionally depolarizing all RGB projection lights is provided between the emission side of the combined light of the color combination prism and the incident side of the projection lens. This makes it possible to completely eliminate the color unevenness of the 3D image when the 3D glasses are not tilted, and eliminate the color unevenness and brightness drop of the 3D image when the 3D glasses are tilted. As a result, the 3D image quality can be significantly improved (see Patent Document 1, description paragraphs

[0154] and

[0155] , FIG. 20, etc.).

[0003] Reference List

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-113984 Summary of the invention

[0006] Technical issues

[0007] Therefore, a technology capable of displaying high-quality images is required.

[0008] In view of the above circumstances, an object of the present technology is to provide an image display device and an image display unit capable of displaying high-quality images.

[0009] Solution to the problem

[0010] In order to achieve the above-mentioned object, an image display device according to an embodiment of the present technology includes: a light emitting unit and a polarization conversion element.

[0011] The light emitting unit emits image light.

[0012] The polarization conversion element has an incident surface, converts the polarization state of image light entering the incident surface, emits the converted light as image light in a non-polarized state, and is configured so that conversion characteristics of the polarization state are non-uniform in the incident surface.

[0013] In the image display device, a polarization conversion element is provided, which converts the conversion state of image light and emits the converted light as image light in a non-polarized state. The polarization conversion element is configured so that the conversion characteristics of the polarization state are non-uniform in the incident surface. As a result, the image light can be fully depolarized and a high-quality image can be displayed.

[0014] The polarization conversion element may add a phase difference to the image light entering the incident surface, and may be configured so that the phase difference added to the image light is non-uniform in the incident surface.

[0015] The polarization conversion element may be configured such that the birefringence with respect to the image light is non-uniform in the incident surface.

[0016] The polarization conversion element may have an exit surface that emits image light in a non-polarized state, and may be configured such that a thickness from the incident surface to the exit surface in an optical axis direction of the image light is non-uniform in the incident surface.

[0017] The polarization conversion element may be configured such that conversion characteristics of a polarization state change in a continuous manner along a predetermined direction in an incident surface.

[0018] The exit surface may be inclined in a predetermined direction relative to the incident surface.

[0019] The predetermined direction may be a direction corresponding to an up-down direction or a right-left direction of an image formed by the image light.

[0020] The polarization conversion element may be configured so that a difference between a minimum phase difference and a maximum phase difference added to the image light is equal to or greater than ¼ of a reference wavelength of the image light.

[0021] The reference wavelength may be a wavelength included in a blue band.

[0022] The image display device may further include a suppression member having a suppression incident surface and a suppression exit surface, wherein the image light in a non-polarized state emitted from the polarization conversion element enters the suppression incident surface, and the suppression exit surface emits the image light in a non-polarized state that enters the suppression incident surface. In this case, the suppression member may be configured to be able to emit the image light from the suppression exit surface while suppressing a change in the optical distance of the image light from the incident surface to the exit surface of the polarization conversion element.

[0023] The polarization conversion element may have an exit surface that emits image light in a non-polarized state. In this case, the suppression member is arranged so that the suppression incident surface is in contact with the exit surface. Alternatively, the suppression member may be arranged so that the suppression incident surface is close to the exit surface in parallel.

[0024] The suppression member may be disposed so that the suppression exit surface is parallel to the incident surface.

[0025] The suppressing member may be configured so that the distance from the incident surface to the suppressed emission surface is uniform in the optical axis direction of the image light.

[0026] The suppression member may have the same shape as the polarization conversion element.

[0027] The suppressing member may be formed of a material having no optical anisotropy.

[0028] The refractive index of the suppressing member can be specified based on the refractive index of the polarization conversion element.

[0029] The polarization conversion element may be formed of a uniaxial crystalline material or a uniaxial organic material.

[0030] The image display device may further include a projection unit that projects the image light in a non-polarized state emitted from the polarization conversion element. In this case, the light emitting unit may include a light modulation element that modulates the incident light and emits the image light.

[0031] An image display unit according to an embodiment of the present technology includes a polarization conversion element.

[0032] The polarization conversion element has an incident surface, converts the polarization state of image light entering the incident surface, emits the converted light as image light in a non-polarized state, and is configured so that conversion characteristics of the polarization state are non-uniform in the incident surface.

[0033] The image display unit may further include: a suppression member having a suppression incident surface and a suppression exit surface, wherein the image light in a non-polarized state emitted from the polarization conversion element enters the suppression incident surface, and the suppression exit surface emits the image light in a non-polarized state that enters the suppression incident surface. In this case, the suppression member may be configured to be able to emit the image light from the suppression exit surface while suppressing a change in the optical distance of the image light from the incident surface to the exit surface of the polarization conversion element. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] [ Figure 1 ] Figure 1 is a schematic diagram showing a configuration example of an image display device according to the first embodiment.

[0035] [ Figure 2 ] Figure 2 is a diagram for describing an example of converting a polarization state to generate light in a non-polarization state.

[0036] [ Figure 3 ] Figure 3 is a schematic diagram showing a configuration example of a polarization scrambler.

[0037] [ Figure 4 ] Figure 4 is a schematic diagram showing a configuration example of a polarization scrambler.

[0038] [ Figure 5 ] Figure 5 is a diagram schematically showing image light propagating from the reflective light modulation element to the screen 1 .

[0039] [ Figure 6 ] Figure 6 It is a graph used to describe the polarization characteristics of a polarization scrambler.

[0040] [ Figure 7 ] Figure 7 It is a graph used to describe the polarization characteristics of a polarization scrambler.

[0041] [ Figure 8 ] Figure 8 It is a graph used to describe the polarization characteristics of a polarization scrambler.

[0042] [ Fig. 9 ] Fig. 9 is a schematic diagram showing another configuration example of a polarization scrambler.

[0043] [ Fig.10 ] Fig.10 is a schematic diagram showing a configuration example of an image display device according to a second embodiment.

[0044] [ Fig.11 ] Fig.11 is a schematic diagram showing a configuration example of a suppression member.

[0045] [ Fig.12 ] Fig.12 : is a graph showing the result of simulation evaluation of the occurrence of astigmatism (using a polarization scrambler having a uniform thickness without a suppressing member).

[0046] [ Fig.13 ] Fig.13 is a graph showing the result of simulation evaluation of the occurrence of astigmatism (using a polarization scrambler having a non-uniform thickness without a suppressing member).

[0047] [ Fig.14 ] Fig.14 is a graph showing the result of simulation evaluation of the occurrence of astigmatism (using a polarization scrambler and a suppressing member having non-uniform thickness).

[0048] [ Fig.15 ] Fig.15 is a schematic diagram showing another configuration example of a suppressing member.

[0049] [ Fig.16 ] Fig.16 is a schematic diagram showing another configuration example of the image generating unit.

[0050] [ Fig.17 ] Fig.17 is a schematic diagram showing another configuration example of the image generating unit.

[0051] [ Fig.18 ] Fig.18is a schematic diagram showing another configuration example of the image generating unit. DETAILED DESCRIPTION

[0052] Embodiments according to the present technology will now be described with reference to the drawings.

[0053] <First Embodiment>

[0054] [Image display device]

[0055] Figure 1 1 is a schematic diagram showing a configuration example of an image display device according to a first embodiment of the present technology. The image display device 100 is used as a projector for, for example, presentations or digital movies. The present technology described below is also applicable to image display devices for other applications.

[0056] The image display apparatus 100 includes a light source unit 101 , an illumination optical system 110 , an image generating unit 130 , and a projection optical system 140 .

[0057] The light source unit 101 generates white light W and emits the generated white light W to the illumination optical system 110. In the light source unit 101, for example, a solid-state light source such as an LED (Light Emitting Diode) and an LD (Laser Diode), a mercury lamp, a xenon lamp, etc. is provided.

[0058] For example, a solid-state light source for RGB capable of emitting light of each color of RGB may be used, and the emitted light may be combined to generate white light W. Alternatively, a solid-state light source emitting light in a blue wavelength band and a phosphor excited by blue light and emitting yellow fluorescence may be provided. In this case, blue light and yellow light are combined to emit white light W.

[0059] The illumination optical system 110 includes an integrator element 111 , a polarization conversion element 112 , polarization elements 113 and 114 , a condenser lens 115 , a cross dichroic mirror 116 , reflection mirrors 117 and 118 , a dichroic mirror 119 , and relay lenses 120 , 121 , and 122 .

[0060] The integrator element 111 includes a first fly-eye lens 111a and a second fly-eye lens 111b. The white light W is transmitted through the first fly-eye lens 111a and the second fly-eye lens 111b, and the brightness non-uniformity of the white light W is reduced.

[0061] The polarization conversion element 112 has a function of making the polarization state of the white light W entering through the integrator element 111 uniform. As the polarization conversion element 112, any optical element such as a PS converter can be used. The white light W having passed through the polarization conversion element 112 is emitted to the cross dichroic mirror 116 through the condenser lens 115.

[0062] The cross dichroic mirror 116 separates the white light W emitted from the condenser lens 115 into red light R on the long wavelength side and green light G and blue light B on the short wavelength side. The red light R separated by the cross dichroic mirror 116 is reflected by the reflection mirror 117 and enters the polarization element 113. The polarization element 113 makes the red light R whose polarization state is uniform be emitted to the image generation unit 130 through the relay lens 120. Note that as the polarization element 113, any optical element such as a polarization plate can be used.

[0063] The green light G and blue light B separated by the cross dichroic mirror 116 are reflected by the reflection mirror 118 and enter the polarization element 114. The polarization element 114 makes the green light G and blue light B with uniform polarization state separated by the dichroic mirror 119 into the green light G on the long wavelength side and the blue light B on the short wavelength side.

[0064] The green light G separated by the dichroic mirror 119 is emitted to the image generating unit 130 through the relay lens 121. The blue light B separated by the dichroic mirror 119 is emitted to the image generating unit 130 through the relay lens 122.

[0065] The image generating unit 130 includes a reflective polarizing element 131 (131R, 131G, 131B), a reflective light modulating element 132 (132R, 132G, 132B), a wavelength plate 133 (133R, 133G, 133B), and a polarizing plate 134 (134R, 134G, 134B) for each color of RGB. In addition, the image generating unit 130 includes a color combining prism 135 and a polarization scrambler 136.

[0066] Reflective polarizing element 131 is a wire grid polarizer. Figure 1 Each of the illustrated relay lenses 120 to 122 emits each light of RGB so as to be P-polarized with respect to the optical plane of the reflective polarizing element 131 .

[0067] The reflective polarizing element 131R emits the P-polarized component of the red light R to the wavelength plate 133R. The wavelength plate 133R functions as a compensation plate for compensating for black brightness floating, rotates the polarization direction of the incident red light R, and emits the red light R to the reflective light modulation element 132R. The rotation angle of the polarization direction is appropriately set so that a high-precision image is projected.

[0068] The reflective light modulation element 132R modulates and reflects the incident red light R based on an image signal corresponding to the red light R provided from the outside. The modulated red light R is emitted as image light forming a red image (hereinafter, the same reference numerals are used and referred to as image light R). As the reflective light modulation element 132R, a reflective liquid crystal panel is generally used, but the present technology is not limited thereto.

[0069] Image light R emitted from reflective light modulation element 132R enters reflective polarization element 131R via wavelength plate 133R. S-polarization component of image light R is reflected by the optical plane and enters polarization plate 134R disposed on the optical path of image light R.

[0070] The polarizing plate 134R makes the polarization state of the image light R uniform and cuts off unnecessary light. For example, linear polarized light whose polarization direction is parallel to the transmission axis (polarization axis) of the polarizing plate 134R is transmitted through the polarizing plate 134R and emitted. It goes without saying that the present technology is not limited to this arrangement configuration. The image light R emitted from the polarizing plate 134 is emitted to the color combining prism 135.

[0071] Similarly, the green light G and the blue light B are modulated by the reflective light modulation elements 132G and 132B, and are emitted as the image light G forming a green image and the image light B forming a blue image. The image lights G and B are reflected by the reflective polarization elements 131G and 131B, and enter the polarization plates 134G and 134B, respectively, which are disposed on the optical paths of the image lights G and B. For example, the image lights G and B are emitted to the color combining prism 135 as linear polarized lights each having a polarization direction parallel to the transmission axis of each polarization plate 134G and 134B.

[0072] In this embodiment, an inorganic polarizing plate is used as polarizing plate 134 (134R, 134G, 134B). It goes without saying that the present technology is not limited thereto, and a polarizing plate having an arbitrary structure may be used.

[0073] In this embodiment, the reflective light modulation elements 132 ( 132R, 132G, 132B) correspond to light modulation elements that modulate incident light and emit image light.

[0074] The color combination prism 135 is formed, for example, by joining a plurality of glass prisms (four right-angle isosceles prisms having substantially the same shape). Two interference films having predetermined optical properties are formed on the joining surface of each glass prism. The first interference film of the interference films reflects blue light B and allows red light R and green light G to pass through. The second interference film reflects red light R and allows blue light B and green light G to pass through.

[0075] The image lights R and B are reflected by the joining surface, and the image light G is transmitted through the joining surface. As a result, the images RGB are combined on the same optical path, and the image light 10 forming a color image is generated. The image light 10 is emitted to the polarization scrambler 136 .

[0076] The polarization scrambler 136 converts the polarization state of the incident light and emits the converted light as light in a non-polarized state. In this embodiment, the polarization state of the image light 10 (image light R, G, B) that has been transmitted through the polarization plates 134R, 134G, and 134B and combined is converted, and the converted light is emitted as image light 10' in a non-polarized state. In this embodiment, the polarization scrambler 136 serves as a polarization conversion element.

[0077] Light in a non-polarized state is light that is not polarized, and includes, for example, natural light. In addition, light having a polarization direction that is substantially uniformly distributed in all directions is also included in the light in a non-polarized state. In addition, light including light having various polarization states is also included in the light in a non-polarized state. In addition, light including a plurality of lights having polarization components of substantially equal intensity and polarization directions different from each other is also included in the light in a non-polarized state.

[0078] Hereinafter, in some cases, the degree of non-polarization state will be referred to as the degree of scrambling. For example, in the case of emitting two lights having the same wavelength band, the light including more lights of different polarization states is the light having a higher degree of scrambling. It goes without saying that the present technology is not limited to lights having the same wavelength band. In addition, in the case of comparing lights having wavelength bands different from each other, the light including more lights of different polarization states is the light having a higher degree of scrambling.

[0079] The projection optical system 140 amplifies the image light 10' converted into the light in the non-polarized state by the polarization scrambler 136 at a predetermined magnification, and projects the amplified light onto a projection target (e.g., a screen). Thus, a color image is displayed. The projection optical system 140 includes, for example, a plurality of projection lenses, etc., and its specific configuration can be appropriately designed. In this embodiment, the projection optical system 140 corresponds to a projection unit that projects the image light in the non-polarized state emitted from the polarization conversion element.

[0080] By converting the image light 10 into the image light 10' in a non-polarized state, color unevenness and brightness reduction due to the reflective characteristics of the projection target (e.g., a screen) can be prevented. For example, depending on the incident angle and polarization state of the light entering the projection target, the reflectivity of the light is different in some cases. In this case, in the case where there is a difference in the polarization state of each image light of RGB, the reflectivity of each color of light will vary, resulting in color unevenness and brightness reduction. In this embodiment, since the image light 10 is converted into the image light 10' in a non-polarized state, the reflectivity of the lights of the various colors are substantially equal to each other, thereby suppressing color unevenness and brightness reduction.

[0081] In addition, there is a system in which light of a predetermined polarization state is transmitted by 3D glasses and is viewed as a right-eye image and a left-eye image. Even in such a system, by converting the image light 10 into the image light 10' of a non-polarized state, the occurrence of color unevenness and brightness reduction can be sufficiently prevented. In addition, even in the case of displaying an image by an ultra-short throw projector or the like, the occurrence of color unevenness and brightness reduction can be sufficiently prevented by applying the present technology.

[0082] In this embodiment, the component that emits the image light 10 to the polarization scrambler 136 implements a light emitting unit that emits the image light. For example, the reflective polarization element 131, the reflective light modulation element 132, the wavelength plates 133 and 134, and the color combination prism 135 implement the light emitting unit. The specific configuration of the light emitting unit is not limited, and any configuration may be adopted. In addition, only the color combination prism 135 can be regarded as an embodiment of the light emitting unit according to the present technology.

[0083] Furthermore, in this embodiment, the polarization scrambler 136 implements the image display unit. The image display unit may be configured to be interchangeable with the image display device 100.

[0084] [Example of Generating Image Light 10' in a Non-Polarized State]

[0085] Figure 2 is a diagram for describing an example of converting a polarization state to produce light in a non-polarized state. Here, in order to facilitate understanding of the present technology, the use of different Figure 1 The case of polarization scrambler 900 is shown as polarization scrambler 136 .

[0086] The polarization scrambler 900 is an element having an optical axis and capable of converting a polarization state by adding a phase difference to two polarization components perpendicular to each other of incident light. For example, the polarization scrambler 900 can be implemented by a material having optical anisotropy. Note that the optical axis corresponds to a slow axis or a fast axis.

[0087] The polarization scrambler 900 is configured to have a uniform thickness in the optical axis direction of the incident light. By appropriately controlling the thickness of the polarization scrambler 900, Figure 2 The polarization characteristics shown in part B of . This makes it possible to convert the polarization state of the incident light so that the polarization state is different for each wavelength of the incident light.

[0088] For example, when light included in a predetermined wavelength band (light including a plurality of wavelengths of light) enters the polarization scrambler 900 , light of a non-polarized state including light of various polarized states may be generated.

[0089] Note that the polarization scrambler 900 has a polarization distribution over the entire incident surface 901 where light enters. Figure 2The polarization characteristic shown in part B of FIG. That is, the polarization scrambler 900 is configured so that the polarization characteristic is uniform in the incident surface 901. In this embodiment, the polarization characteristic corresponds to the conversion characteristic of the polarization state.

[0090] like Figure 2 As shown in part A of FIG. 1 , two polarizing plates 15 and 16 are arranged so that their transmission axes 15a and 16a are substantially perpendicular to each other. Then, a polarization scrambler 900 is arranged between them, and the cross Nicol transmittance of each wavelength has been measured.

[0091] like Figure 2 As shown in part B of , for each wavelength, the transmittance changes periodically. The change in transmittance corresponds to the change in the polarization state. For example, wavelength light with a transmittance value close to 0% corresponds to light whose polarization state is not converted by the polarization scrambler 900. This light is linearly polarized light whose polarization direction is parallel to the transmission axis 15a of the polarizing plate 15.

[0092] Light of a wavelength having a transmittance value close to 100% corresponds to light whose polarization direction is rotated by approximately 90° by the polarization scrambler 900. This light is linearly polarized light whose polarization direction is parallel to the transmission axis 16a of the polarizing plate 16.

[0093] like Figure 2 As schematically shown in the B portion of FIG. 1 , wavelength light having a transmittance value close to 50% corresponds to light to be converted into circularly polarized light by the polarization scrambler 900. Wavelength light having a transmittance in the range of 0% to 50% corresponds to light to be converted into vertically prolongated elliptically polarized light (elliptically polarized light having many polarization components parallel to the transmission axis 15a). Wavelength light having a transmittance in the range of 50% to 100% corresponds to light to be converted into horizontally prolongated elliptically polarized light (elliptically polarized light having many polarization components parallel to the transmission axis 16a).

[0094] As described above, the light that has entered the polarization scrambler 900 is converted into light of a polarization state different for each wavelength. For example, the red band 17R, the green band 17G, and the blue band 17B, each surrounded by a dotted line, include light of various polarization states. As a result, the image light R, G, B of each color is converted into light R1, G1, B1 of a non-polarized state by the polarization scrambler 900. Note that the band of each color is not limited to Figure 2 The bands shown in part B.

[0095] The polarization scrambler 900 is formed of, for example, a uniaxial crystal material. An inorganic material having an axis on the material itself, such as quartz, sapphire, lithium niobate, and yttrium vanadate, can be used. For example, the polarization scrambler 136 is formed so that the optical axis is not 0° / 90° (450°, 1350° are effective) with respect to the image light 10 without Z cut. Needless to say, the present technology is not limited to this.

[0096] In addition, the polarization scrambler 900 may be formed of, for example, a uniaxial organic material. For example, the polarization scrambler may also be implemented by an organic film (eg, polycarbonate and polyolefin).

[0097] In addition, in order to realize the polarization scrambler 900, an arbitrary configuration may be adopted. Any wavelength plate using quartz, a wavelength plate film, an inorganic phase difference film, etc. may be used as the polarization scrambler 900. Note that when the polarization scrambler 900 is formed to have each configuration of a multilayer film, a multilayer inorganic deposited film, and a multilayer quartz, the polarization scrambler 900 having the multilayer quartz configuration has higher hygroscopicity and degradation resistance, etc. In view of this, the polarization scrambler 900 using an inorganic material (e.g., quartz) is considered to be effective for an image display device of a high brightness model. It goes without saying that the application of the present technology is not limited to such a material or configuration.

[0098] In the present disclosure, in some cases, an optical operation of adding a phase difference to two polarization components of incident light that are perpendicular to each other is expressed as adding a phase difference to the incident light. In addition, in the present disclosure, any optical element capable of adding a phase difference to the incident light is included in the phase difference plate. That is, any phase difference plate can be used as the polarization scrambler 900.

[0099] [Polarization Scrambler 136]

[0100] The polarization scrambler 136 according to this embodiment will be described in detail. Figure 3 and Figure 4 Each is a schematic diagram showing a configuration example of the polarization scrambler 136 . Figure 5 is a diagram schematically showing image light 10 ( 10 ′) propagating from the reflective light modulation element 132 to the screen 1 .

[0101] exist Figure 5 In order to make the description easier to understand, the configuration of the reflective light modulation element 132, the polarization scrambler 136, the projection optical system 140 and the screen 1 arranged linearly is schematically shown. That is, the Figure 1 The color combination prism 135 shown in FIG. Figure 5 An example of generating image light 10' in a non-polarized state is described, but the principle is similarly applicable to Figure 1 Configuration shown.

[0102] like Figure 1 , Figure 5 As shown in FIG. 1 , the polarization scrambler 136 is disposed perpendicular to the optical axis direction C of the image light 10 . The optical axis direction of the image light 10 can be specified by, for example, an axis through which a light beam (also referred to as pixel light) at the center of the image light 10 emitted from the pixel P1 at the center of the reflective light modulation element 132 passes.

[0103] Pixel light is diffused and emitted from each pixel of the reflective light modulation element 132. The pixel light of each pixel is collected on the screen 1 by the projection optical system 140 or the like. As a result, the individual pixels forming the image 2 are displayed on the screen 1. For example, the pixel light emitted from the pixel P1 located at the center of the reflective light modulation element 132 is displayed as the pixel P2 located at the center of the image 2 on the screen 1.

[0104] Hereinafter, the optical axis direction of the image light 10 (pixel light) entering the polarization scrambler 136 will be referred to as the Z direction. Furthermore, the direction corresponding to the right-left direction of the image 2 formed by the image light 10 will be referred to as the X direction, and the direction corresponding to the up-down direction of the image 2 will be referred to as the Y direction. Furthermore, for the sake of convenience, the X direction, the Y direction, and the Z direction will be described as the right-left direction, the up-down direction, and the thickness direction with respect to the polarization scrambler 136, respectively.

[0105] exist Figure 5 In the illustrated configuration, the right-left direction and the up-down direction of the polarization scrambler 136 and the right-left direction and the up-down direction of the image 2 are the same directions, respectively. It goes without saying that the present technology is not limited thereto. Depending on the configurations of the illumination optical system 110, the image generation unit 130, and the projection optical system 140, the right-left direction and the up-down direction of the polarization scrambler 136 and the right-left direction and the up-down direction of the image 2 are different directions in some cases.

[0106] Figure 3 Part A is a front view of the polarization scrambler 136 as viewed from the incident surface side.

[0107] Figure 3 Part B is a top view of the polarization scrambler 136 as viewed from above.

[0108] Figure 4 Part A is a perspective view of the polarization scrambler 136 viewed from the incident surface side.

[0109] Figure 4 Part B is a perspective view of the polarization scrambler 136 viewed from the exit surface side.

[0110] The polarization scrambler 136 has an incident surface 20 into which the image light 10 enters and an exit surface 21 which emits the image light 10' in a non-polarized state. In addition, the polarization scrambler 136 has an upper surface 22, a lower surface 23, a left side surface 24, and a right side surface 25 which surround the incident surface 20 from the upper, lower, left, and right directions as viewed from the front of the incident surface 20.

[0111] The polarization scrambler 136 converts the polarization state of the image light 10 entering the incident surface 20, and emits the converted light as the image light 10' in a non-polarized state from the exit surface 21. In addition, the polarization scrambler 136 is configured so that the conversion characteristics of the polarization state are non-uniform in the incident surface 20. That is, the polarization characteristics differ depending on the position where the image light 10 enters the incident surface 20.

[0112] In this embodiment, a phase difference may be added to the image light 10 entering the incident surface 20, and the polarization scrambler 136 is configured so that the phase difference added to the image light 10 is not uniform in the incident surface 20. That is, the polarization scrambler 136 is configured so that the birefringence with respect to the image light 10 is not uniform in the incident surface 20.

[0113] like Figure 3 and Figure 4 As shown, the polarization scrambler 136 is formed of a predetermined material having optical anisotropy so that the thickness from the incident surface 20 to the exit surface 21 in the optical axis direction of the image light 10 is non-uniform in the incident surface 20. Note that the non-uniform thickness in the incident surface 20 means that the thickness in the optical axis direction C at each position in the incident surface 20 is non-uniform.

[0114] The phase difference added to the image light 10 is specified by the product of the thickness and the difference between the refractive index in the slow axis and the refractive index in the fast axis. In this regard, the polarization scrambler 136 is formed of a material in which the difference between the refractive index in the slow axis and the refractive index in the fast axis is uniform, so that the thickness is non-uniform. As a result, a configuration in which the conversion characteristics of the polarization state are non-uniform in the incident surface 20 can be easily realized.

[0115] like Figure 3 and Figure 4 As shown, in this embodiment, the exit surface 21 is inclined relative to the incident surface 20 along the right-left direction (corresponding to the right-left direction of the image 2). Figure 3 As shown in the top view of the portion B of FIG. 1 , the thickness of the polarization scrambler 136 decreases in a continuous manner along the right-left direction. As a result, the conversion characteristics of the polarization state can be changed in a continuous manner along the right-left direction in the incident surface 20. In this embodiment, the right-left direction corresponds to a predetermined direction.

[0116] like Figure 3 As shown in the B part of FIG. 1 , the dimension of the left side surface 24 along the optical axis direction is the minimum thickness d1 of the polarization scrambler 136. The dimension of the right side surface 25 along the optical axis direction is the maximum thickness d2 of the polarization scrambler 136. The difference Δd between the thickness d1 and the thickness d2 is a parameter related to the polarization characteristic difference. That is, the difference Δd is a parameter related to the phase difference added to the image light 10.

[0117] For example, assume that the thickness d1 is 0.450 mm and the thickness d2 is 0.500 mm. In this case, the difference Δd is 0.050 mm. With this design, the image light 10 can be fully converted into the image light 10' in a non-polarized state.

[0118] Note that the method of setting the thickness d1, the thickness d2, and the difference Δd between the thicknesses is not limited and can be set arbitrarily. For example, in the image light 10 that is desired to be converted into light in a non-polarized state, a reference wavelength λ is set. For example, a wavelength of light that is difficult to convert into a non-polarized state, etc. is used as a reference wavelength. It goes without saying that the present technology is not limited thereto.

[0119] The minimum thickness d1 and the maximum thickness d2 are set so that the difference between the minimum phase difference and the maximum phase difference added to the image light 10 is equal to or greater than 1 / 4 of the reference wavelength λ. For example, the polarization scrambler 136 is designed so that the product of the difference between the refractive index in the slow axis and the refractive index in the fast axis and the thickness difference Δd is equal to or greater than 1 / 4 of the reference wavelength λ. As a result, the image light 10 can be sufficiently converted into the image light 10' in a non-polarized state.

[0120] [Polarization Characteristics of the Polarization Scrambler 136]

[0121] Figures 6 to 8 are graphs for describing the polarization characteristics of the polarization scrambler 136. Figures 6 to 8 and Figure 5 The polarization characteristics of the polarization scrambler 136 are described.

[0122] Here, if Figure 6 As shown in FIG. 1 , taking the case where white light W is generated by a blue laser beam and yellow light as an example, the blue laser beam has a central wavelength (peak wavelength) of 453 nm, and yellow light is generated by excitation of the blue laser beam.

[0123] In addition, if Figure 6 As shown in , the luminous bandwidth of white light W (i.e., the band in which the radiant flux (W / nm) is greater than 0.0) will be separately described as a blue band B (approximately 446nm to approximately 463nm), a green band G (approximately 490nm to approximately 575nm), and a red band R (approximately 475nm to approximately 678nm).

[0124] refer to Figure 5 , assuming that light with a wavelength of 453 nm is emitted from the pixel P1 at the center of the reflective light modulation element 132. Figure 5 , among the pixel lights diffused from the central pixel P1, light L0 passing through the center of the polarization scrambler 136 (light propagating in the optical axis direction C), light L1 passing through the left end of the center of the polarization scrambler 136, and light L2 passing through the right end are shown.

[0125] Figure 6 2 is a graph showing the polarization characteristic S1 corresponding to the minimum thickness d1. For example, it can be said that this is the polarization characteristic of the polarization scrambler 900 formed to have a uniform thickness d1. Figure 6 The polarization characteristic S1 shown corresponds to the action passing through Figure 5 Polarization characteristics of light L1 at the left end (near the left side surface 24) are shown.

[0126] like Figure 6 As shown, in the blue band B, light of polarization states with a cross Nicol transmittance of 0% to about 62% is included. Meanwhile, in the green band G and the red band R, light of polarization states with a transmittance of 0% to 100% is included. Therefore, in the blue band B having a narrow spectral distribution, the degree of scrambling is lower than that in the green band G and the red band R having a wide spectral distribution.

[0127] Figure 7 1 is a graph showing polarization characteristics S1 corresponding to the minimum thickness d1, polarization characteristics S2 corresponding to the maximum thickness d2, and polarization characteristics S3 corresponding to the intermediate thickness. The polarization characteristics S2 corresponding to the maximum thickness d2 corresponds to the polarization characteristics acting on the Figure 5 The polarization characteristics on the light L2 at the right end (near the right side surface 25) are shown. In addition, the polarization characteristics S3 corresponding to the intermediate thickness correspond to the polarization characteristics acting on the light L0 propagating in the optical axis direction C.

[0128] Figure 8 It is shown Figure 7 The graph shown is an enlarged graph of the 453nm wavelength light portion. Figure 8 In the example, the ratio of the vertical axis to the horizontal axis is different from Figure 7 The ratio in .

[0129] The thickness of the polarization scrambler 136 changes from the thickness d1 to the thickness d2 in a continuous manner along the right-left direction. As a result, the polarization characteristic of the polarization scrambler 136 changes from the polarization characteristic S1 to the polarization characteristic S2 in a continuous manner along the right-left direction. As a result, Figure 7 As shown, in the blue band B, light of a polarization state with a transmittance of 0% to 100% can be generated. That is, even with a narrow spectral distribution, light with a high degree of scrambling can be generated, similar to the green band G and the red band R.

[0130] like Figure 5 and Figure 8As shown, light L1 passing through the left end of the polarization scrambler 136 is converted into vertical long elliptically polarized light by polarization characteristic S1. Light L0 passing through the center is converted into circularly polarized light by polarization characteristic S3. Light L2 passing through the right end is converted into horizontal long elliptically polarized light by polarization characteristic S2. Even in the case where only 453nm wavelength light is seen, light from vertical long elliptically polarized light to horizontal long elliptically polarized light is generated. Therefore, in the entire blue band B, light with a sufficiently high scrambling degree is generated. It goes without saying that the scrambling degree is also improved for the green band G and the red band R.

[0131] For example, a wavelength of 453 nm included in a blue band having a narrow spectral distribution can be used as a reference wavelength to design the polarization characteristics of the polarization scrambler 136. It goes without saying that another wavelength in the blue band can be selected as the reference wavelength. In addition, a wavelength included in a green band or a red band different from the blue band can be selected as the reference wavelength.

[0132] Note that Figure 5 In the polarization scrambler 136 shown, the polarization characteristics do not change in the up-down direction of the incident surface 20. Generally, the image light 10 is emitted so that the brightness distribution is constant over the entire panel. Therefore, by changing the polarization characteristics in a continuous manner along the direction corresponding to the right-left direction of the image 2, the image light 10' with a high degree of scrambling can be emitted. Note that the polarization scrambler 136 can be configured so that the polarization characteristics change in a continuous manner along the up-down direction of the image 2. That is, the polarization scrambler 136 can be configured so that the thickness changes in a continuous manner along the up-down direction of the image 2.

[0133] Fig. 9 is a schematic diagram showing another configuration example of a polarization scrambler. Fig. 9 Parts A to E of 30 to 34 show variations in configuration in which polarization characteristics of the polarization scramblers 30 to 34 are non-uniform in the incident surfaces 30a to 34a, respectively. Specifically, the polarization scramblers 30 to 34 are configured so that the thickness is non-uniform in the incident surfaces 30a to 34a, respectively.

[0134] like Fig. 9 As shown in part A of FIG. 3 , a configuration in which the exit surface 30 b is tilted relative to the incident surface 30 a in both the X direction and the Y direction may be adopted. Fig. 9 In the example shown in part A of , the thickness changes at the same ratio in each of the X direction and the Y direction. Therefore, the thickness changes along the middle direction between the X direction and the Y direction (the direction intersecting the X direction and the Y direction at an angle of 45° as viewed from the Z direction).

[0135] like Fig. 9As shown in part B of the embodiment, the exit surface 31 may have a curved surface shape. For example, the exit surface 31b is formed so that the shape viewed from the Y direction is a curved shape from the left side surface of the minimum thickness d1 toward the right side surface of the maximum thickness d2. The specific shape of the curved surface is not limited and can be arbitrarily designed.

[0136] like Fig. 9 As shown in part C of FIG. 3 , a step 32c may be formed in the exit surface 32b. By forming the step 32c, the thickness in the incident surface 32a may be made non-uniform, and the polarization characteristics may be made non-uniform. The number, position, size (height), etc. of the step 32c may be arbitrarily designed.

[0137] like Fig. 9 As shown in the D part of FIG. 1 , the configuration in which the emission surface 33 b is formed to have a protruding shape to form a protruding lens shape as a whole may be adopted. Fig. 9 As shown in part E of FIG. 1 , a configuration in which the exit surface 33b is formed to have a protruding shape to form a concave lens shape may be adopted. Even with this configuration, the thickness in the incident surface 32a can be made uneven, and the polarization characteristics can be made uneven. The curvature and the like of the protruding shape and the concave shape are not limited and can be arbitrarily designed. In addition, an arbitrary configuration can be adopted. For example, by appropriately designing the shape of the polarization scrambler according to the area where the image light 10 enters and the wavelength band of the light source to be used, etc., it is possible to generate and emit sufficiently scrambled light in a non-polarized state.

[0138] Furthermore, the thickness can be controlled by changing the shape of the incident surfaces 30 a to 34 a side.

[0139] In addition, the configuration in which the polarization characteristics in the incident surface become non-uniform is not limited to the case in which the thickness becomes non-uniform. By appropriately controlling the material, physical properties, etc. forming the polarization scrambler, the polarization characteristics in the incident surface can be made non-uniform while the thickness is made uniform. For example, by appropriately controlling the material or physical properties forming the polarization scrambler, the polarization scrambler can be configured so that the phase difference added to the incident light is non-uniform in the incident surface. In addition, the polarization scrambler can be configured so that the birefringence is non-uniform in the incident surface. As a result, image light in a non-polarized state having a high degree of scrambling can be generated and emitted. It goes without saying that the control of the thickness and the control of the material or physical properties can be performed.

[0140] As described above, in the image display device 100 according to the embodiment, the polarization scrambler 136 is provided, which converts the conversion state of the image light 10 and emits the converted light as the image light 10' in a non-polarized state. The polarization scrambler 136 is configured so that the conversion characteristics of the polarization state are not uniform in the incident surface 20. As a result, the image light 10 can be sufficiently depolarized and a high-quality image can be displayed.

[0141] Since image light 10 can be more scrambled, polarization interference in a projection lens or the like can be made less noticeable, and uneven polarization can be substantially reduced when performing short-focus projection or using a special screen (e.g., silver screen / bead screen / prism screen / white board).

[0142] Furthermore, even with respect to narrow spectrum light sources, such as LDs and LEDs, sufficiently scrambled light in an unpolarized state can be generated.

[0143] Furthermore, since light of various polarization states can be multiplexed, it is possible to reduce speckle and display high-quality images.

[0144] <Second Embodiment>

[0145] An image display device according to a second embodiment of the present technology will be described. In the following description, descriptions of configurations and effects similar to those in the image display device 100 described in the above embodiment will be omitted or simplified.

[0146] Fig.10 1 is a schematic diagram showing a configuration example of an image display device 200 according to this embodiment. Regarding the image display device 200, components identical to those in the image display device 100 according to the first embodiment are denoted by the same reference numerals. In the image display device 200 according to this embodiment, the suppression member 137 is provided on the polarization scrambler 136.

[0147] Fig.11 1 is a schematic diagram showing a configuration example of the suppression member 137. Fig.11 As shown, the suppression member 137 includes a suppression incident surface 40 and a suppression exit surface 41. The suppression incident surface 40 is a surface from which the image light 10' in a non-polarized state emitted from the polarization scrambler 136 enters. The suppression exit surface 41 is a surface from which the image light 10' in a non-polarized state that has entered the suppression incident surface 40 is emitted.

[0148] like Fig.11 As shown in part B of the suppression member 137, the suppression member 137 is configured to be able to emit the image light 10' from the suppression exit surface 41 while suppressing a change in the optical distance of the image light 10' from the incident surface 20 to the exit surface 21 of the polarization scrambler 136. This can be said to suppress a change in the optical distance of the image light 10' from the incident surface 20 of the polarization scrambler 136 to the suppression exit surface 41 of the suppression member 137. Note that the optical distance is a parameter specified by multiplying a distance that light actually propagates by the refractive index of an object through which the light passes.

[0149] For example, the suppression member 137 is formed of a material that does not have optical anisotropy, such as optical glass. Fig.11 That is, the suppressing member 137 is configured so that the thickness of the image light 10 ′ in the optical axis direction changes in the right-left direction (X direction) at the same ratio as that of the polarization scrambler 136 .

[0150] Then, if Fig.11 As shown, the suppressing member 137 is disposed so that the inclined surface of the suppressing member 137 as the suppressing incidence surface 40 contacts the exit surface 21 of the polarization scrambler 136. The suppressing member 137 is disposed so that the polarization scrambler 136 and the suppressing member 137 form a rectangular parallelepiped shape as a whole.

[0151] As a result, the suppression exit surface 41 of the suppression member 137 is parallel to the incident surface of the polarization scrambler 136. In addition, the suppression member 137 is disposed so that the distance from the incident surface 20 to the suppression exit surface 41 is uniform in the optical axis direction of the image light 10'. As a result, the image light 10' can be easily emitted from the suppression exit surface 41 while suppressing a change in the optical distance of the image light 10' from the incident surface 20 to the exit surface 21 of the polarization scrambler 136.

[0152] Note that the exit surface 21 of the polarization scrambler 136 and the suppressed incidence surface 40 of the suppressing member 137 may be in contact with each other via any adhesive or the like. In this case, the adhesive may be regarded as a part of the suppressing member. In addition, processing such as polishing is performed on the suppressed incidence surface 40, the suppressed exit surface 41, and the like of the suppressing member 137. As a result, the image light 10' can be emitted without reducing the accuracy of the transmission wavefront.

[0153] For example, it is assumed that the polarization scrambler 136 is formed of quartz having a refractive index of about 1.58. The refractive index of quartz having optical axis anisotropy can be specified by, for example, the refractive index on the slow axis or the fast axis. The suppression member 137 formed of a material having a refractive index of 1.47 to 1.80 is provided on such a polarization scrambler 136. As a result, compared to a case where the suppression member 137 is not provided (i.e., the image light 10' is emitted from the exit surface 21 toward the air having a refractive index of 1), the image light 10' can be emitted while suppressing a change in the optical distance of the image light 10' from the incident surface 20 to the exit surface 21.

[0154] That is, the change in optical distance can be sufficiently suppressed by appropriately specifying the refractive index of the suppressing member 137 based on the refractive index of the polarization scrambler 136. For example, by making the refractive index of the suppressing member 137 equal to the refractive index of the polarization scrambler 136, a high effect is exhibited.

[0155] Figure 12 to Figure 14 Graphs showing simulation evaluation results regarding the occurrence of astigmatism of the polarization scrambler 136 and the suppressing member 137 , respectively.

[0156] The "modulation" of the vertical axis of the graph is an axis that indicates how faithfully the image 2 can be reproduced relative to the original image (an axis that indicates the contrast of the image 2 focused on the screen 1). For example, assuming that the original image is an image that alternately displays black and white for each dot, the degree of faithfulness of the contrast that can be reproduced can be evaluated by the appearance of the image 2 on the screen 1.

[0157] On the vertical axis, 1 corresponds to a state where contrast can be fully reproduced (black·white·black·white...), and 0 corresponds to a state where contrast is not reproduced at all (gray·gray·gray·gray...). Intermediate values ​​between 0 and 1 correspond to states where contrast is highly reproduced when the value is close to 1 (e.g., dark gray·whitish gray·dark gray·whitish gray...).

[0158] “Defocus position (mm)” on the horizontal axis indicates the focus position in the optical axis direction in the case of drawing a light beam in which light emitted from the image 2 projected on the screen 1 is focused on the reflective light modulation element 132 .

[0159] In this figure, the results for light emitted from the same predetermined pixel of the projected image 2 are shown.

[0160] The solid line graph represents light focused in the sagittal direction. The dashed line graph represents light focused in the meridional direction.

[0161] The peak difference between the solid line and the dotted line indicates the difference between the focus positions of the light focused in the sagittal direction and the light focused in the meridional direction in the optical axis direction. The larger the position difference, the blurrier the focused light. The smaller the difference, the clearer the focused light. As shown in the figure, the peak difference between the solid line and the dotted line corresponds to the magnitude of astigmatism.

[0162] Fig.12 The graph of 136 shows the simulation result in the case where the polarization scrambler 136 is provided, and the polarization scrambler 136 is formed of a uniaxial crystal material and is configured so that the thickness of the image light 10' in the optical axis direction is uniform. Note that the suppression member 137 is not provided. Fig.12 As shown, it can be seen that the astigmatism is small and high focusing performance is exhibited.

[0163] Fig.13 The graph of shows the simulation result in the case where the polarization scrambler 136 is provided, the polarization scrambler 136 is formed of a uniaxial crystal material, and is configured so that the thickness of the image light 10' in the optical axis direction changes continuously in the right-left direction. That is, Fig.13 The graph shows the setting Figure 3 , Figure 4 The simulation results of the case of the polarization scrambler 136 shown in FIG. 1 and FIG. 2 are shown in FIG. 3 . Note that the suppression member 137 is not provided. Fig.13 As shown, it can be seen that astigmatism increases and focusing performance decreases.

[0164] Fig.14 The graph of shows the simulation result in the case where the polarization scrambler 136 and the suppression member 137 are provided, and the polarization scrambler 136 is formed of a uniaxial crystal material so that the thickness of the image light 10' in the optical axis direction changes in a continuous manner in the right-left direction. That is, Fig.14 The graph shows that when using Fig.11 The simulation results for the configuration shown are as follows. Fig.14 As shown, it can be seen that the astigmatism is small and high focusing performance is exhibited.

[0165] That is, even in the case of using the polarization scrambler 136 whose polarization characteristics are not uniform in the incident surface 20 , it is possible to prevent the focus performance from being degraded by providing the suppressing member 137 .

[0166] Fig.15 is a schematic diagram showing another configuration example of a suppressing member. Fig.15 Parts A to C of FIG. 1 show variations of a configuration in which the suppressing members 50 to 53 are respectively provided on the polarization scrambler 136 to form a rectangular parallelepiped shape as a whole.

[0167] like Fig.15 As shown in the portion A of FIG. 1 , the suppression member 50 may be configured to have a shape different from the polarization scrambler 136. For example, the suppression incident surface 50a is in contact with the inclined surface (inclined interface) as the exit surface 21 of the polarization scrambler 136. Then, the suppression exit surface 50b is formed parallel to the incident surface 20 in conformity with the tip portion in the optical axis direction of the polarization scrambler 136. As a result, a rectangular parallelepiped shape in which the thickness in the optical axis direction is equal to the maximum thickness d2 of the polarization scrambler 136 is achieved.

[0168] like Fig.15 As shown in the B part of FIG. 1 , the suppression member 51 formed of optical glass or the like and having a rectangular parallelepiped shape is arranged perpendicular to the optical axis direction. Then, an adhesive 54 is applied between the exit surface 21 as the inclined interface of the polarization scrambler 136 and the suppression incident surface 51a of the suppression member 51. The suppression member 51 is pressed against the polarization scrambler 136 along the optical axis direction while controlling the position of the suppression exit surface 51b of the suppression member 51. As a result, the polarization scrambler 136 and the suppression member 51 are connected to each other via the adhesive 54.

[0169] As described above, the gap between the exit surface 21 of the polarization scrambler 136 and the suppressed incidence surface 51a of the suppressing member 51 can be filled with the adhesive 54. Furthermore, by appropriately setting the refractive index of the adhesive 54, the function of suppressing the variation in the optical distance can be enhanced.

[0170] exist Fig.15 In the configuration shown in part B of FIG. 1 , the adhesive 54 can be regarded as a part of the suppression member. In this case, a part of the adhesive 54 in contact with the exit surface 21 of the polarization scrambler 136 is the suppression incidence surface. In addition, in the case where the shape of the adhesive 54 can be appropriately controlled, the suppression member can also be realized by only the adhesive 54.

[0171] like Fig.15 As shown in part C of FIG. 1 , a gap (air gap) 55 having a very small width may be formed between the exit surface 21 of the polarization scrambler 136 and the suppressed incidence surface 53a of the suppression member 53. For example, the air gap 55 having a width of about 1 to 3 μm can reduce the influence on the function of suppressing the change in the optical distance. Fig.15 As in the configuration shown in part C of FIG. 5 , the suppression member 53 may be disposed so that the suppression incident surface 53 a approaches the exit surface 21 in parallel.

[0172] Furthermore, the material, refractive index, etc. of the suppression member are not limited, and any configuration may be employed that can suppress the variation in the optical distance of the image light 10' from the incident surface 20 to the exit surface 21 of the polarization scrambler 136. For example, even in the case where the suppression member is implemented by a material having optical anisotropy, the variation in the optical distance of the image light 10' can be suppressed.

[0173] Furthermore, the function of suppressing the variation of the optical distance by the suppression member is effective for the polarization scrambler 136 configured so that the polarization characteristic is non-uniform in the incident surface but the thickness is uniform. By appropriately designing the shape of the suppression member according to the polarization characteristic of the polarization scrambler 136, the variation of the optical distance of the image light from the incident surface 20 to the exit surface 21 of the polarization scrambler 136 can be suppressed.

[0174] In this embodiment, the polarization scrambler 136 and the suppressing member 137 implement an image display unit. The image display unit may be configured to be interchangeable with the image display device 200.

[0175] As described above, in the image display device 200 according to the embodiment, the suppressing member 137 is provided on the polarization scrambler 136. As a result, the image light 10' can be emitted from the suppression exit surface 41 while suppressing the change in the optical distance of the image light 10' from the incident surface 20 to the exit surface 21 of the polarization scrambler 136. That is, the suppressing member 137 makes it possible to increase the astigmatism reduction function. As a result, the astigmatism can be made sufficiently small and a high-quality image can be displayed.

[0176] In addition, since astigmatism can be made sufficiently small, focusing performance, axial chromatic aberration, magnification chromatic aberration, etc. can also be improved.

[0177] In addition, since the inclined interface of the polarization scrambler 136 can be covered by the suppression member 137, the reflected light reflected on the inclined interface can be prevented from being applied to another unintended optical part. That is, ghosting or the like due to the inclined interface can be prevented. In addition, the ANSI contrast can be prevented from being reduced.

[0178] <Other embodiments>

[0179] The present technology is not limited to the above-described embodiments, and various other embodiments can be implemented.

[0180] Figures 16 to 18 and are schematic diagrams showing another configuration example of the image generating unit. Fig.16 As in the image generating unit 330 shown, another polarizing element such as a prism type beam splitter can be used as the reflective polarizing element 331 (331R, 331G, 331B) instead of the wire grid polarizer. In addition, the direction in which the reflective light modulation element 332 (332R, 332G, 332B) is set is not limited and can be appropriately designed.

[0181] like Fig.17 As in the illustrated image generating unit 430, the transmissive light modulating element 432 (432R, 432G, 432B) may be used. For example, a polarizing plate or a compensating plate is disposed so as to sandwich the transmissive light modulating element 432. In addition, any configuration may be employed.

[0182] exist Fig.18 In the image generating unit 530 shown, the green image light G modulated by the reflective light modulating element 532G is reflected by the reflective polarizing element 531G and enters the color combining prism 535. The red image light R modulated by the reflective light modulating element 532R and the image light B modulated by the reflective light modulating element 532B are emitted by the reflective light modulating element 531RB along the same optical path and enter the color combining prism 535.

[0183] Also in Figures 16 to 18 In the configuration shown, the polarization scrambler (336, 436, 536) is provided on the optical path of the image light 10 (image light R, G, B). As a result, the polarization state of the image light 10 can be sufficiently depolarized, and the obtained light can be emitted as the image light 10' of the non-polarized state. As a result, a high-quality image can be displayed. It goes without saying that the suppression member can be provided on the polarization scrambler.

[0184] As the light modulation element, in addition to the liquid crystal panel, an arbitrary device such as a digital micromirror device (DMD) can be used.

[0185] The configuration of the image display device, light source unit, illumination optical system, image generation unit, projection optical system, polarization scrambler, suppression member, etc. described with reference to the drawings is only one embodiment and can be arbitrarily modified without departing from the essence of the present technology. That is, any other configuration for implementing the present technology can be adopted.

[0186] In the present disclosure, concepts specifying shapes, sizes, positional relationships, states, etc. (for example, "center", "middle", "uniform", "equal", "same", "vertical", "parallel", "perpendicular", "symmetrical", "extended", "axial", "rectangular parallelepiped shape", "curved shape", "curved shape" and "lens shape") are concepts including "substantially center", "substantially middle", "substantially uniform", "substantially equal", "substantially the same", "substantially perpendicular", "substantially parallel", "substantially perpendicular", "substantially symmetrical", "substantially extended", "substantially axial", "substantially rectangular parallelepiped shape", "substantially curved shape", "substantially curved shape" and "substantially lens shape".

[0187] For example, the error range is expressed by "perfectly centered", "perfectly in the middle", "perfectly uniform", "perfectly equal", "exactly identical", "perfectly perpendicular", "perfectly parallel", "perfectly perpendicular", "perfectly symmetrical", "perfectly extended", "perfectly axial", "perfectly axial", "perfectly cuboid shape", "perfectly curved shape", "perfectly curved shape", and "perfectly lens shape".

[0188] At least two features of the present technology described above can also be combined. In other words, the various features described in each embodiment can be combined arbitrarily without distinguishing the embodiments. In addition, the various effects described above are not restrictive, but merely illustrative, and other effects can be provided.

[0189] Note that the present technology can also adopt the following configurations.

[0190] (1) An image display device comprising:

[0191] a light emitting unit that emits image light; and

[0192] A polarization conversion element has an incident surface, converts the polarization state of image light entering the incident surface, emits the converted light as image light in a non-polarized state, and is configured to make conversion characteristics of the polarization state non-uniform in the incident surface.

[0193] (2) The image display device according to (1), wherein:

[0194] The polarization conversion element adds a phase difference to the image light entering the incident surface, and is configured so that the phase difference added to the image light is non-uniform in the incident surface.

[0195] (3) The image display device according to (1) or (2), wherein:

[0196] The polarization conversion element is configured so that the birefringence with respect to the image light is non-uniform in the incident surface.

[0197] (4) The image display device according to any one of (1) to (3), wherein:

[0198] The polarization conversion element has an exit surface that emits image light in a non-polarized state, and is configured such that a thickness from the incident surface to the exit surface in an optical axis direction of the image light is non-uniform in the incident surface.

[0199] (5) The image display device according to any one of (1) to (4), wherein:

[0200] The polarization conversion element is configured so that conversion characteristics of a polarization state change in a continuous manner along a predetermined direction in an incident surface.

[0201] (6) The image display device according to (4), wherein:

[0202] The exit surface is inclined in a predetermined direction relative to the incident surface.

[0203] (7) The image display device according to (5) or (6), wherein:

[0204] The predetermined direction is a direction corresponding to the up-down direction or the right-left direction of an image formed by the image light.

[0205] (8) The image display device according to (2), wherein:

[0206] The polarization conversion element is configured so that a difference between a minimum phase difference and a maximum phase difference added to the image light is equal to or greater than 1 / 4 of a reference wavelength of the image light.

[0207] (9) The image display device according to (8), wherein:

[0208] The reference wavelength is a wavelength included in the blue band.

[0209] (10) The image display device according to any one of (1) to (9), further comprising:

[0210] a suppression member having a suppression incident surface, the image light in a non-polarized state emitted from the polarization conversion element entering the suppression incident surface, and a suppression exit surface emitting the image light in a non-polarized state entering the suppression incident surface, wherein

[0211] The suppressing member is configured to be able to emit the image light from the suppressing exit surface while suppressing a change in an optical distance of the image light from the incident surface to the exit surface of the polarization conversion element.

[0212] (11) The image display device according to (10), wherein:

[0213] The polarization conversion element has an exit surface that emits image light in a non-polarized state, and

[0214] The suppressing member is disposed so that the incident surface is suppressed from contacting with the exit surface, or the suppressing member is disposed so that the incident surface is suppressed from approaching the exit surface in parallel.

[0215] (12) The image display device according to (10) or (11), wherein:

[0216] The suppressing member is disposed so that the suppressing exit surface is parallel to the incident surface.

[0217] (13) The image display device according to any one of (10) to (12), wherein:

[0218] The suppressing member is configured so that a distance from the incident surface to the suppressed emission surface is uniform in the optical axis direction of the image light.

[0219] (14) The image display device according to any one of (10) to (13), wherein:

[0220] The suppression member has the same shape as the polarization conversion element.

[0221] (15) The image display device according to any one of (10) to (14), wherein:

[0222] The suppressing member is formed of a material having no optical anisotropy.

[0223] (16) The image display device according to any one of (10) to (15), wherein:

[0224] The refractive index of the suppressing member is specified based on the refractive index of the polarization conversion element.

[0225] (17) The image display device according to any one of (1) to (16), wherein:

[0226] The polarization conversion element is formed of a uniaxial crystal material or a uniaxial organic material.

[0227] (18) The image display device according to any one of (1) to (17), further comprising

[0228] a projection unit that projects image light in a non-polarized state emitted from the polarization conversion element, wherein

[0229] The light emitting unit includes a light modulation element that modulates incident light and emits image light.

[0230] (19) An image display unit comprising:

[0231] A polarization conversion element has an incident surface, converts the polarization state of image light entering the incident surface, emits the converted light as image light in a non-polarized state, and is configured so that conversion characteristics of the polarization state are non-uniform in the incident surface.

[0232] (20) The image display unit according to (19), further comprising

[0233] a suppression member having a suppression incident surface, the image light in a non-polarized state emitted from the polarization conversion element entering the suppression incident surface, and a suppression exit surface emitting the image light in a non-polarized state entering the suppression incident surface, wherein

[0234] The suppressing member is configured to be able to emit image light from the suppressing exit surface while suppressing a change in an optical distance of the image light from the incident surface to the exit surface of the polarization conversion element.

[0235] Reference numerals list

[0236] C Optical axis direction

[0237] S1 to S3 polarization characteristics

[0238] 10 Image Light

[0239] 10' Image light in non-polarized state

[0240] 20, 30a to 34a Incident surface

[0241] 21, 30b to 34b exit surfaces

[0242] 30 to 34 Polarization Scrambler

[0243] 40, 50a to 53a suppress incident surface

[0244] 41, 50b to 53b suppress emission surface

[0245] 50 to 53 Suppression components

[0246] 54 Adhesives

[0247] 55 Air Gap

[0248] 100, 200 image display equipment

[0249] 110 Illumination Optical System

[0250] 130, 330, 430, 530 image generation unit

[0251] 135 color combination prism

[0252] 136 Polarization Scrambler

[0253] 137 Suppression Components

[0254] 140 projection optical system.

Claims

1. An image display device, comprising: A light emitting unit, emitting image light; as well as A polarization conversion element having an incident surface, converting the polarization state of the image light entering the incident surface, emitting the converted light as image light in a non-polarized state, and configured so that, when the wavelength of predetermined light included in the image light is set as a reference wavelength and the incident position of the light of the reference wavelength in the incident surface moves along a predetermined direction, the conversion characteristics of the polarization state change in a continuous manner relative to the light of the reference wavelength.

2. The image display device according to claim 1, wherein: The polarization conversion element adds a phase difference to the image light entering the incident surface, and is configured such that the phase difference added to the light of the reference wavelength changes in a continuous manner when the incident position of the light of the reference wavelength in the incident surface moves along a predetermined direction.

3. The image display device according to claim 1, wherein: The polarization conversion element is configured such that, when an incident position of the light of the reference wavelength in the incident surface moves along a predetermined direction, a birefringence index with respect to the light of the reference wavelength changes in a continuous manner.

4. The image display device according to claim 1, wherein: The polarization conversion element has an exit surface that emits image light in a non-polarized state, and the polarization conversion element is configured so that the thickness from the incident surface to the exit surface in the optical axis direction of the image light changes in a continuous manner along a predetermined direction, and the exit surface is inclined in a predetermined direction relative to the incident surface.

5. The image display device according to claim 1, wherein: The predetermined direction is a direction corresponding to an up-down direction or a right-left direction of an image formed by the image light.

6. The image display device according to claim 2, wherein: The polarization conversion element is configured so that a difference between a minimum phase difference and a maximum phase difference added to the image light is equal to or greater than ¼ of the reference wavelength of the image light.

7. The image display device according to claim 6, wherein: The blue wavelength band of the image light is a wavelength band having the narrowest spectral distribution, and the reference wavelength is a wavelength included in the blue wavelength band.

8. The image display device according to claim 1, further comprising: a suppressing member having a suppressing incident surface into which the image light in a non-polarized state emitted from the polarization conversion element enters and a suppressing exit surface onto which the image light in a non-polarized state entering the suppressing incident surface is emitted, wherein The suppressing member is configured to be able to emit image light from the suppressing exit surface while suppressing a change in an optical distance of the image light from the incident surface to the exit surface of the polarization conversion element.

9. The image display device according to claim 8, wherein: The polarization conversion element has an exit surface that emits image light in a non-polarized state, and The suppressing member is disposed so that the incidence suppressing surface is in contact with the emission surface, or the suppressing member is disposed so that the incidence suppressing surface is close to the emission surface in parallel.

10. The image display device according to claim 8, wherein: The suppressing member is disposed so that the emission suppressing surface is parallel to the incidence surface.

11. The image display device according to claim 8, wherein: The suppressing member is configured so that a distance from the incident surface to the suppressing exit surface is uniform in an optical axis direction of the image light.

12. The image display device according to claim 8, wherein: The suppressing member has the same shape as the polarization conversion element.

13. The image display device according to claim 8, wherein: The suppressing member is formed of a material having no optical anisotropy.

14. The image display device according to claim 8, wherein: The refractive index of the suppressing member is specified based on the refractive index of the polarization conversion element.

15. The image display device according to claim 1, wherein: The polarization conversion element is formed of a uniaxial crystal material or a uniaxial organic material.

16. The image display device according to claim 1, further comprising a projection unit that projects image light in a non-polarized state emitted from the polarization conversion element, wherein: The light emitting unit includes a light modulation element that modulates incident light and emits image light.

17. An image display unit, comprising: A polarization conversion element has an incident surface, converts the polarization state of image light entering the incident surface, emits the converted light as image light in a non-polarized state, and is configured so that, when the wavelength of predetermined light included in the image light is set as a reference wavelength and the incident position of the light of the reference wavelength in the incident surface moves along a predetermined direction, the conversion characteristics of the polarization state change in a continuous manner relative to the light of the reference wavelength.

18. The image display unit according to claim 17, further comprising a suppressing member having a suppressing incident surface into which the image light in a non-polarized state emitted from the polarization conversion element enters and a suppressing exit surface onto which the image light in a non-polarized state entering the suppressing incident surface is emitted, wherein The suppressing member is configured to be able to emit image light from the suppressing exit surface while suppressing a change in an optical distance of the image light from the incident surface to the exit surface of the polarization conversion element.

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