Image display device and image display method

Abstract

Provided is an image display device with which it is possible to improve image reproducibility and / or improve image visibility by a simple configuration.　An image display device according to the present technology comprises: a light source system that includes at least one laser light source and emits laser light modulated according to image information; a branch optical path selection system that includes an optical path branching unit that branches an optical path of the laser light from the light source system into a plurality of branch optical paths; and an optical path synthesis system that synthesizes the plurality of branch optical paths. The branch optical path selection system further includes a first optical processing system that selects, as the branch optical path through which the laser light travels from the optical path branching unit, at least one branch optical path among the plurality of branch optical paths, and performs optical processing on the laser light traveling through some branch optical paths among the plurality of branch optical paths.

Description

Image display device and image display method

[0001] The technology according to the present disclosure (hereinafter also referred to as "the technology") relates to an image display device and an image display method.

[0002] 2. Description of the Related Art Conventionally, there has been known an image display device that guides light from a light source to allow an image to be viewed (see, for example, Patent Documents 1 to 3).

[0003] JP 2017-32631 A JP 2015-162526 A JP 2008-309827 A

[0004] However, conventional image display devices have room for improvement in terms of improving image reproducibility and / or improving image visibility with a simple configuration.

[0005] Therefore, a main object of the present technology is to provide an image display device that can improve the reproducibility of an image and / or can improve the visibility of an image with a simple configuration.

[0006] The present technology provides an image display device comprising: a light source system including at least one laser light source and emitting laser light modulated according to image information; a branched optical path selection system including an optical path branching unit that branches an optical path of the laser light from the light source system into multiple branched optical paths; and an optical path combining system that combines the multiple branched optical paths, wherein the branched optical path selection system selects at least one of the multiple branched optical paths as the branched optical path along which the laser light from the optical path branching unit travels; and a first optical processing system that performs optical processing on the laser light traveling along some of the multiple branched optical paths. The branched optical path selection system may make the selection based on the image information. In the light source system, the magnitude of excitation of the laser light source may exceed an oscillation threshold, and the first optical processing system may include an optical attenuation unit that attenuates the laser light traveling along some of the branched optical paths. The branched optical path selection system may select the part of the branched optical paths as the branched optical paths along which the laser beam travels from the optical path branching unit when the luminance of the image information is within a first luminance range equal to or less than a predetermined value, and may select another part of the branched optical paths among the plurality of branched optical paths as the branched optical paths along which the laser beam travels from the optical path branching unit when the luminance of the image information is within a second luminance range greater than the predetermined value. The first optical processing system may include a detouring unit that detours the laser beam traveling along the part of the branched optical paths. The branched optical path selection system may select the part of the branched optical paths as the branched optical paths along which the laser beam travels from the optical path branching unit when the laser beam is modulated in accordance with a first pixel region of the image information in frame units, and may select the other part of the plurality of branched optical paths as the branched optical paths along which the laser beam travels from the optical path branching unit when the laser beam is modulated in accordance with a second pixel region of the image information in frame units. The branched optical path selection system may alternately select one of the branched optical paths as the branched optical path along which the laser light travels from the optical path branching section and select another of the plurality of branched optical paths at least every frame.The image display device may further include an another branched optical path selection system including an another optical path branching unit that branches the optical path combined from the plurality of branched optical paths in the optical path combining system into a plurality of other branched optical paths, and an another optical path combining system that combines the plurality of other branched optical paths, wherein the another branched optical path selection system selects at least one of the plurality of other branched optical paths as the other branched optical path along which the laser light travels from the other optical path branching unit based on the image information, and further includes a second optical processing system that performs optical processing on the laser light traveling along some of the other branched optical paths among the plurality of other branched optical paths. The other branched optical path selection system may select the part of the other branched optical paths as the other branched optical paths along which the laser beam travels from the other optical path branching unit when the luminance of the image information is within a first luminance range equal to or less than a predetermined value, and may select another part of the other branched optical paths from the other optical path branching unit as the other branched optical path along which the laser beam travels when the luminance of the image information is within a second luminance range greater than the predetermined value. The second optical processing system may include a detouring unit that detours the laser beam traveling along the part of the other branched optical paths. The other branched optical path selection system may select the part of the other branched optical paths as the other branched optical paths along which the laser beam travels from the other optical path branching unit when the laser beam is modulated in accordance with a first pixel region of the image information in frame units, and may select the other part of the other branched optical paths from the other optical path branching unit as the other branched optical path along which the laser beam travels when the laser beam is modulated in accordance with a second pixel region of the image information in frame units. The branched optical path selection system may alternately select one of the branched optical paths as the branched optical path along which the laser light travels from the optical path branching section and select another of the plurality of branched optical paths at least every frame.The branched optical path selection system may include a polarization state variable element that can vary the polarization state of the laser light from the light source system, and at least the optical path branching unit among the optical path branching unit and the optical path combining system may include a polarizing beam splitter. The other branched optical path selection system may include a polarization state variable element that can vary the polarization state of the laser light from the optical path combining system, and at least the other optical path branching unit among the other optical path branching unit and the optical path combining system may include a polarizing beam splitter. The at least one laser light source may be a plurality of laser light sources having different emission wavelengths, and the branched optical path selection system, the optical path combining system, and the first optical processing system may be provided for each laser light source. The optical path branching unit may include an element in which a plurality of pixels are arranged two-dimensionally. The other optical path branching unit may include an element in which a plurality of pixels are arranged two-dimensionally. The present technology also provides an image display method including: emitting laser light modulated according to image information; selecting at least one branched optical path from among a plurality of branched optical paths as the branched optical path along which the laser light, whose optical path is branched into a plurality of branched optical paths, travels based on the image information; when a branched optical path from among the plurality of branched optical paths is selected as the branched optical path along which the laser light travels, performing a first optical processing on the laser light traveling along the one branched optical path; and combining the plurality of branched optical paths. The present technology also provides an image display method including: selecting at least one branched optical path from among a plurality of other branched optical paths as the one branched optical path along which the laser light, whose optical path is branched into a plurality of other branched optical paths, travels; and when a branched optical path from among the plurality of other branched optical paths is selected as the one branched optical path along which the laser light travels, performing a second optical processing on the laser light traveling along the one branched optical path; and combining the plurality of other branched optical paths.

[0007] 1 is a diagram showing current-light output characteristics of a normal laser light source. FIG. 1 is a diagram showing a configuration of an image display device according to Example 1 of an embodiment of the present technology. FIG. 2 is a block diagram showing functions of an image display device according to Example 1 of an embodiment of the present technology. FIG. 3 is a diagram showing current-light intensity characteristics of light that has passed through a light attenuation unit and light that has not passed through a light attenuation unit. FIG. 4 is a flowchart for explaining operation of an image display device according to Example 1 of an embodiment of the present technology. FIG. 5 is a diagram showing a configuration of an image display device according to Example 2 of an embodiment of the present technology. FIG. 6 is a block diagram showing functions of an image display device according to Example 2 of an embodiment of the present technology. FIG. 7 is a flowchart for explaining operation of an image display device according to Example 3 of an embodiment of the present technology. FIG. 8 is a diagram showing functions of an image display device according to Example 3 of an embodiment of the present technology. FIG. 9 is a flowchart for explaining operation of an image display device according to Example 3 of an embodiment of the present technology. FIG. 10 is a diagram showing a configuration of an image display device according to Example 4 of an embodiment of the present technology. FIG. 11 is a block diagram showing functions of an image display device according to Example 4 of an embodiment of the present technology. FIG. 12 is a block diagram showing functions of an image display device according to Example 5 of an embodiment of the present technology. FIG. 13 is a diagram showing a configuration of an image display device according to a modified example of Example 5 of an embodiment of the present technology. FIG. 1 is a diagram illustrating a configuration of an image display device according to Example 6 of an embodiment of the present technology. FIG. 2 is a block diagram illustrating functions of an image display device according to Example 6 of an embodiment of the present technology. FIG. 3 is a diagram illustrating a configuration of an image display device according to a modified example of Example 6 of an embodiment of the present technology. FIG. 4 is a diagram illustrating a configuration of an image display device according to Example 7 of an embodiment of the present technology. FIG. 5 is a block diagram illustrating functions of an image display device according to Example 7 of an embodiment of the present technology. FIG. 6 is a diagram illustrating a configuration of an image display device according to a modified example of Example 7 of an embodiment of the present technology. FIG. 7 is a diagram illustrating a configuration of an image display device according to a modified example of Example 1 of an embodiment of the present technology. FIG. 8 is a diagram illustrating a configuration of an image display device according to a modified example of Example 2 of an embodiment of the present technology. FIG. 9 is a diagram illustrating a configuration of an image display device according to a modified example of Example 4 of an embodiment of the present technology.

[0008] Preferred embodiments of the present technology will be described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description will be omitted. The embodiments described below illustrate typical embodiments of the present technology, and the scope of the present technology should not be interpreted as being narrow. Even when it is described in this specification that an image display device and an image display method according to the present technology have multiple effects, it is sufficient that the image display device and the image display method according to the present technology have at least one effect. The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0009] The description will be made in the following order: 0. Introduction 1. Image display device according to Example 1 of an embodiment of the present technology 2. Image display device according to Example 2 of an embodiment of the present technology 3. Image display device according to Example 3 of an embodiment of the present technology 4. Image display device according to Example 4 of an embodiment of the present technology 5. Image display device according to Example 5 of an embodiment of the present technology 5.5. Image display device according to a modified example of Example 5 of an embodiment of the present technology 6. Image display device according to a modified example of Example 6 of an embodiment of the present technology 6.5. Image display device according to a modified example of Example 6 of an embodiment of the present technology 7. Image display device according to Example 7 of an embodiment of the present technology 7.5. Image display device according to a modified example of Example 7 of an embodiment of the present technology 8. Modified examples of the present technology

[0010] <0. Introduction> Conventionally, in a laser beam scanning type image display device, brightness gradation is created by utilizing the IL characteristic (current-light output characteristic) of a laser light source. However, as shown in the partially enlarged view of FIG. 1, the IL characteristic of a laser light source is particularly affected by the threshold current I th Below this level, linearity is lost, and the optical output becomes unstable depending on oscillation conditions such as temperature. This instability also causes problems such as color shifts in low-brightness areas of the image due to different characteristics for each wavelength.

[0011] Previously, methods have been proposed that simply add dynamic attenuation to gradation expression. Methods for dynamically changing the amount of light include those that use polarization or diffraction, but these methods have the problem of varying the light attenuation rate depending on the wavelength. In other words, the light attenuation rate changes depending on the ambient temperature, and the dynamic range when attenuated differs depending on the wavelength. As such, there has been room for improvement in the past in terms of improving image reproducibility.

[0012] Furthermore, there has been a demand for improving the visibility of images with a simple configuration.

[0013] Therefore, after extensive research, the inventors have developed an image display device according to the present technology as an image display device that can improve image reproducibility and / or can improve image visibility with a simple configuration.

[0014] Specifically, for example, in the image display device according to the present technology, by setting the excitation of the laser light source relatively high (for example, above the oscillation threshold) and by switching the optical path of the laser light to attenuate it according to image information, a large optical attenuation rate of, for example, 20 dB to 40 dB can be obtained, thereby improving the reproducibility of low-brightness areas.Furthermore, in the image display device according to the present technology, by switching the optical path of the laser light between optical paths with different optical path lengths according to image information, the resolution of the image can be partially or temporarily increased, thereby improving visibility.

[0015] 1. Image display device according to Example 1 of an embodiment of the present technology> (Configuration of image display device) An image display device according to Example 1 of an embodiment of the present technology will be described with reference to the drawings. Fig. 2 is a diagram showing the configuration of an image display device 10 according to Example 1 of an embodiment. Fig. 3 is a block diagram showing the functions of the image display device 10 according to Example 1 of an embodiment. Fig. 4 is a diagram showing the current-light intensity characteristics of light that has passed through a light attenuating unit 501 and light that has not passed through the light attenuating unit 501.

[0016] The image display device 10 is used for providing, for example, AR (Augmented Reality), VR (Virtual Reality), or the like to a user.

[0017] The image display device 10 functions as, for example, an HMD (head-mounted display) that is worn on the head of a user. An HMD is also called, for example, eyewear. As an example, the image display device 10 is provided on a support structure (for example, an eyeglass frame). The following description will be given on the assumption that an eyeglass frame, which is an example of the support structure, is worn on the user's head.

[0018] 2, the image display device 10 includes a light source system 100, a branched optical path selection system 200, an optical path combining system 600, and an optical attenuation unit 501 (first optical processing system). The image display device 10 further includes, for example, a deflector 701, an eyepiece 801, and a control device 1100.

[0019] 3, the light source system 100 includes at least one laser light source 101 and emits laser light modulated in accordance with image information. The light source system 100 further includes a light source driving unit 102 (laser driver) that drives the laser light source 101.

[0020] Examples of the laser light source 101 include semiconductor lasers such as LDs (edge-emitting lasers: EELs) and VCSELs (surface-emitting lasers: SELs), and solid-state lasers such as semiconductor-laser-pumped solid-state lasers. That is, the laser light source 101 may be of a current-pumped type or an optical-pumped type.

[0021] The light source driving unit 102 includes, for example, a transistor, a capacitor, etc. The light source driving unit 102 is controlled by a control device 1100. The image information is input to the control device 1100 from an external device 2000.

[0022] As an example, as shown in FIG. 2, the branched optical path selection system 200 has a first polarized beam splitter 202 as an optical path branching section that branches the optical path of the laser light from the light source system 100 into multiple (e.g., two) branched optical paths (e.g., first and second branched optical paths BOP1 and BOP2).

[0023] Based on image information, the branched optical path selection system 200 selects at least one of a plurality of (e.g., two) branched optical paths (first and second branched optical paths BOP1, BOP2) as the branched optical path along which the laser light travels from the first polarizing beam splitter 202.

[0024] As shown in FIGS. 2 and 3 , the branched optical path selection system 200 includes a polarization state variable element 201 that can change the polarization state of the laser light from the light source system 100. The polarization state variable element 201 is, for example, an electro-optical element (EO element). The EO element is an element that can change the polarization direction of the laser light by rotating the polarization plane of the laser light with an applied voltage. The polarization state variable element 201 is disposed on the optical path of the laser light between the light source system 100 and the first polarizing beam splitter 202 and converts the laser light (e.g., linearly polarized light) from the light source system 100 into either first or second linearly polarized light whose polarization directions are orthogonal to each other. The polarization state variable element 201 is controlled by the control device 1100. Note that a liquid crystal retarder may be used as the polarization state variable element 201 instead of the EO element. The liquid crystal retarder operates in the same manner as the EO element. The polarization state variable element 201 may also be a mechanically rotating polarizer or phase plate (e.g., a half-wave plate).

[0025] As an example, the first polarizing beam splitter 202 reflects, to a first branched optical path BOP1, a first linearly polarized light obtained by converting the laser light emitted from the light source system 100 by the polarization state variable element 201. As an example, the first polarizing beam splitter 202 transmits, to a second branched optical path BOP2, a second linearly polarized light obtained by converting the laser light emitted from the light source system 100 by the polarization state variable element 201.

[0026] The optical path combining system 600 combines the first and second branched optical paths BOP1 and BOP2. The optical path combining system 600 has a half-wave plate 601 as a first retarder, a half-wave plate 602 as a second retarder, and a second polarizing beam splitter 603 as an optical path combining section. Each half-wave plate converts incident linearly polarized light into linearly polarized light whose polarization direction is orthogonal to that of the first linearly polarized light. The second polarizing beam splitter 603 is substantially identical to the first polarizing beam splitter 202.

[0027] The optical path combining system 600 may have a half mirror as a beam splitter instead of the second polarizing beam splitter 603. In this case, the first and second retarders are not necessary. Alternatively, the second polarizing beam splitter 603 may reflect the light that has traveled through the first branched optical path BOP1 and transmit the light that has traveled through the second branched optical path BOP2, thereby combining these lights.

[0028] As an example, a mirror 301, an optical attenuation unit 501, and a half-wave plate 601 are arranged on the first branched optical path BOP1 in this order from the first polarizing beam splitter 202 side. The arrangement order of the mirror 301, the optical attenuation unit 501, and the half-wave plate 601 on the first branched optical path BOP1 can be changed as appropriate.

[0029] As an example, the optical attenuation unit 501 performs optical attenuation processing as optical processing on the laser light traveling through the first branched optical path BOP1. The optical attenuation unit 501 includes an ND (Neutral Density) filter, a diffraction grating, etc. In a broad sense, the diffraction grating also includes a DOE (Diffractive Optical Element) and an HOE (Holographic Optical Element). The optical attenuation unit 501 can have a large optical attenuation rate of, for example, 20 dB to 40 dB. The optical attenuation rate of the optical attenuation unit 501 may be variable.

[0030] The first linearly polarized light reflected by the first polarizing beam splitter 202 to the first branched optical path BOP1 is reflected by the mirror 301 toward the optical attenuation unit 501. The first linearly polarized light incident on the optical attenuation unit 501 is attenuated by the optical attenuation unit 501 and incident on the half-wave plate 601. The first linearly polarized light incident on the half-wave plate 601 is converted into second linearly polarized light by the half-wave plate 601 and incident on the second polarizing beam splitter 603.

[0031] As an example, the mirror 401 and the half-wave plate 602 are arranged on the second branched optical path BOP2 in this order from the first polarizing beam splitter 202 side. The order of the mirror 401 and the half-wave plate 602 on the second branched optical path BOP2 may be reversed.

[0032] The second linearly polarized light that has passed through the first polarizing beam splitter 202 to the second branched optical path BOP2 is reflected by the mirror 401 toward the half-wave plate 602. The second linearly polarized light that has entered the half-wave plate 602 is converted into the first linearly polarized light by the half-wave plate 602 and is then entered into the second polarizing beam splitter 603.

[0033] The second linearly polarized light that passes through the first branched optical path BOP1 and enters the second polarizing beam splitter 603 is transmitted through the second polarizing beam splitter 603. The first linearly polarized light that passes through the second branched optical path BOP2 and enters the second polarizing beam splitter 603 is reflected by the second polarizing beam splitter 603. The second linearly polarized light that passes through the second polarizing beam splitter 603 and the first linearly polarized light that is reflected by the second polarizing beam splitter 603 pass through the same optical path (a combined optical path of the first and second branched optical paths BOP1 and BOP2) and enters the deflector 701. The deflector 701 deflects each of the incident linearly polarized light beams and two-dimensionally scans the retina of the eyeball EB via the eyepiece 801. This allows the user to view an image corresponding to the image information. The deflector 701 includes a combination of two-axis movable mirrors or one-axis movable mirrors, such as a MEMS mirror or a galvanometer mirror. The deflector 701 is controlled by a control device 1100 .

[0034] 3 , the control device 1100 includes a display control unit 1001, an image information input unit 1002, a modulation signal generation unit 1003, a deflector control unit 1004, a brightness determination unit 1005, and a branch optical path selection unit 1006. The control device 1100 is realized by hardware including, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), a chip set, etc.

[0035] The image information input unit 1002 inputs image information (image data) transmitted from an external device 2000 (for example, a smartphone, a personal computer, a camera, etc.). The communication connection between the image information input unit 1002 and the external device 2000 may be a wired connection or a wireless connection.

[0036] The display control unit 1001 generates a synchronization control signal based on the timing at which image information starts to be input into the image information input unit 1002 , and transmits the synchronization control signal to the modulation signal generation unit 1003 and the deflector control unit 1004 .

[0037] Upon receiving the synchronization control signal, the modulation signal generation unit 1003 generates a modulation signal (pulse signal) for modulating and driving the laser light source 101 based on the image information from the image information input unit 1002, and applies the generated signal to the light source drive unit 102. The light source drive unit 102 generates a drive current (pulse current) to be applied to the laser light source 101 in accordance with the applied modulation signal. The light source drive unit 102 controls the excitation level of the laser light source 101 so that it exceeds the oscillation threshold, i.e., the drive current is equal to or exceeds the threshold current I th (See FIG. 4).

[0038] Upon receiving the synchronization control signal, the deflector control unit 1004 generates a drive signal (pulse signal) for driving the deflector 701 and applies the drive signal to the deflector 701. The deflector 701 performs a laser beam scanning operation (e.g., raster scanning) in accordance with the applied drive signal. Note that the deflector control unit 1004 does not necessarily have to be a component of the control device 1100.

[0039] The brightness determination unit 1005 determines whether the brightness of the image information is within a first brightness range (low brightness range) below a predetermined value, or within a second brightness range (high brightness range) above the predetermined value, and transmits the determination result to the branch optical path selection unit 1006. The predetermined value is a value corresponding to the light intensity P2 shown in FIG. 4. The first brightness range is a brightness range corresponding to the light intensity range P1 to P2 (P1<P2) in FIG. 4. The second brightness range is a brightness range corresponding to the light intensity range P2 to P3 (P2<<P3) in FIG. 4. P1 is a threshold current I th P2 is the light intensity of the laser light emitted at the threshold current I th The intensity of the laser light emitted from the light attenuating unit 501 is the intensity of the laser light that does not pass through the light attenuating unit 501 .

[0040] The branch optical path selection unit 1006 is part of the branch optical path selection system 200, and selects the first branch optical path BOP1 as the branch optical path along which the laser light travels from the first polarizing beam splitter 202 when the luminance of the image information is within a first luminance range (low luminance range), and selects the second branch optical path BOP2 as the branch optical path along which the laser light travels from the first polarizing beam splitter 202 when the luminance of the image information is within a second luminance range (high luminance range). When selecting the first branch optical path BOP1, the branch optical path selection unit 1006 applies a first voltage signal (e.g., a high-level signal) to the polarization state variable element 201 to convert the laser light from the light source system 100 into a first linearly polarized light. When selecting the second branch optical path BOP2, the branch optical path selection unit 1006 applies a second voltage signal (e.g., a low-level signal) to the polarization state variable element 201 to convert the laser light from the light source system 100 into a second linearly polarized light. For example, the second luminance range is wider than the first luminance range, i.e., for example, the light intensity range P2 to P3 is wider than the light intensity range P1 to P2.

[0041] As shown in FIG. 4, the current-light intensity characteristic of the laser light that has passed through the light attenuating unit 501 when the first branched optical path BOP1 is selected is expressed as follows: when the current (horizontal axis) is I th From I max This is a stable characteristic in which the light intensity increases linearly from P1 to P2 at a gentle gradient when the light intensity increases to P1. Therefore, the luminance of the image information in the first luminance range (low luminance range) can be accurately reproduced. Furthermore, in this current-light intensity characteristic, as an example, the current range I corresponding to the light intensity range P1 to P2 th ~I max is wider than the conventional current range corresponding to the light intensity range P1 to P2 (the horizontal axis distance corresponding to the vertical axis distance between P1 and P2 on the two-dot chain line in FIG. 4), so that it is possible to increase the gradation in the low brightness range.

[0042] The dashed line in FIG. 4 indicates the threshold current I th The graph shows the current-light intensity characteristics of laser light when the laser light is emitted with the following current and passes through the light attenuating unit 501. It can be seen that the characteristics are unstable. The dashed two-dot line in FIG. 4 indicates the threshold current I thThe graph shows the current-light intensity characteristics of laser light when laser light is emitted with the following current and does not pass through the light attenuating unit 501, but it can be seen that the characteristics are unstable. th Below this threshold current I, laser oscillation does not occur and only a weak light intensity is obtained as the applied current increases. Since this light is not laser light, it is not possible to obtain a stable light intensity or wavelength. th When the voltage exceeds this threshold, laser oscillation begins, and the resulting light intensity increases in proportion to the applied current. Conventionally, the light intensity for high-gradation display has been kept constant for safety reasons, so when displaying low-brightness range image information, light of unstable intensity other than laser light has been used.

[0043] On the other hand, in the image display device 10, the light used to display the low brightness range (first brightness range) of the image information is attenuated by the light attenuation unit 501, so that it is possible to display the low brightness range using light (laser light) of stable intensity generated by laser oscillation.

[0044] As shown in FIG. 4, the IL characteristic of the laser light source when the second branched optical path BOP2 is selected is such that the current is I th From I max This is a stable characteristic in which the light intensity increases linearly at a steep gradient from P2 to P3 when the light intensity increases to P3. This allows the brightness of the image information in the second brightness range (high brightness range) to be reproduced with high accuracy. The light intensity at which the second branched optical path BOP2 is selected may be greater than P2.

[0045] (Operation of Image Display Device) Hereinafter, the operation of the image display device 10 will be described with reference to Fig. 5. The flowchart in Fig. 5 is based on a processing algorithm executed by the control device 1100. The operation of the image display device 10 shows an image display method using the image display device 10.

[0046] In the first step S1, the image information input unit 1002 sequentially inputs image information (image data) transmitted from the external device 2000, transmits an input timing signal to the display control unit 1001 for each input, and sequentially transmits the input image information to the modulation signal generation unit 1003 and the brightness determination unit 1005.

[0047] In the next step S2, the brightness determination unit 1005 determines whether the brightness of the image information is within the first brightness range (low brightness range), i.e., whether the brightness of the image information is within the first brightness range or the second brightness range (high brightness range). If the determination here is affirmative, the process proceeds to step S3, and if negative, the process proceeds to step S4.

[0048] In step S3, the branched optical path selection unit 1006 selects the first branched optical path BOP1 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202. Specifically, the branched optical path selection unit 1006 applies a first voltage signal to the polarization state varying element 201 to convert the laser light from the light source system 100 into first linearly polarized light. After step S3 is executed, the process proceeds to step S5.

[0049] In step S4, the branched optical path selection unit 1006 selects the second branched optical path BOP2 as the branched optical path along which the laser light travels from the second polarizing beam splitter 202. Specifically, the branched optical path selection unit 1006 applies a second voltage signal to the polarization state varying element 201 to convert the laser light from the light source system 100 into second linearly polarized light. After step S4 is executed, the process proceeds to step S5.

[0050] In step S5, the display control unit 1001 drives the laser light source 101 and the deflector 701 in accordance with the image information. Specifically, the display control unit 1001 transmits a synchronization control signal to the modulation signal generation unit 1003 and the deflector control unit 1004. The modulation signal generation unit 1003 receives the synchronization control signal and generates a modulation signal in accordance with the image information, and applies the modulation signal to the light source drive unit 102. At this time, light modulated in accordance with the image information is emitted from the laser light source 101. The deflector control unit 1004 receives the synchronization control signal and generates a drive signal for driving the deflector 701, and applies the drive signal to the deflector 701. At this time, the deflector 701 performs a laser beam scanning operation.

[0051] In the final step S6, the display control unit 1001 determines whether or not to end the process. This determination is affirmative, for example, when the image display device 10 is turned off, and negative when it remains on. If the determination in step S6 is affirmative, the flow ends, and if negative, the flow returns to step S1.

[0052] (Effects of Image Display Device and Image Display Method) The effects of the image display device 10 and the image display method using the image display device 10 will be described below.

[0053] The image display device 10 comprises a light source system 100 including at least one laser light source 101 and emitting laser light modulated in accordance with image information; a branched optical path selection system 200 including a first polarizing beam splitter 202 that branches the optical path of the laser light from the light source system 100 into first and second branched optical paths BOP1 and BOP2; and an optical path combining system 600 that combines the first and second branched optical paths BOP1 and BOP2, wherein the branched optical path selection system 200 selects at least one branched optical path (e.g., one branched optical path) from the first polarizing beam splitter 202 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202, based on the image information, and further comprises a first optical processing system that performs optical processing on the laser light traveling along the first branched optical path BOP1 of the first and second branched optical paths BOP1 and BOP2.

[0054] In the image display device 10, it is possible to select whether or not to apply the first optical processing to the laser light depending on the image information, so that the optical processing can be reliably applied only to light modulated according to the image information that requires the optical processing.

[0055] As a result, the image display device 10 can provide an image display device that can improve the reproducibility of images.

[0056] In the light source system 100, the magnitude of excitation of the laser light source 101 exceeds the oscillation threshold, and the first optical processing system includes an optical attenuation unit 501 that attenuates the laser light traveling along the first branched optical path BOP1. This makes it possible to generate not only a high-luminance range of an image but also a low-luminance range while stabilizing the optical output of the laser light source 101. In other words, it is possible to improve the reproducibility of the low-luminance range of an image.

[0057] When the brightness of the image information is within a first brightness range that is equal to or less than a predetermined value, the branched optical path selection system 200 selects the first branched optical path BOP1 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202, and when the brightness of the image information is within a second brightness range that is greater than the predetermined value, the branched optical path selection system 200 selects the second branched optical path BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202. This makes it possible to reliably perform optical attenuation processing only on light modulated in accordance with image information that requires optical attenuation processing.

[0058] The second luminance range is wider than the first luminance range, so that there is no need to perform optical processing on light corresponding to image information in the high luminance range that occupies the majority of the dynamic range.

[0059] An image display method using the image display device 10 includes the steps of: emitting modulated laser light according to image information; selecting at least one (e.g., one) branched optical path from among the plurality of branched optical paths as the branched optical path along which the laser light, whose optical path is branched into a plurality of (e.g., two) branched optical paths, travels based on the image information; when a first branched optical path BOP1 from among the plurality of branched optical paths is selected as the branched optical path along which the laser light travels, performing a first optical processing on the laser light traveling along the first branched optical path BOP1; and combining the first and second branched optical paths BOP1 and BOP2.

[0060] According to this image display method, it is possible to select whether or not to apply optical processing to laser light depending on the image information, so that optical processing can be reliably applied only to light modulated according to image information that requires optical processing.

[0061] As a result, the image display method can improve the reproducibility of the image.

[0062] 2. Image display device according to Example 2 of an embodiment of the present technology> (Configuration of image display device) An image display device according to Example 2 of an embodiment of the present technology will be described with reference to the drawings. Fig. 6 is a diagram showing the configuration of an image display device 20 according to Example 2 of an embodiment. Fig. 7 is a block diagram showing functions of the image display device 20 according to Example 2 of an embodiment.

[0063] 6, in the image display device 20, an optical fiber 901 (detouring unit) is provided as a first optical processing system in the first branched optical path BOP1 instead of the light attenuating unit 501. The optical fiber 901 detouring the laser light traveling through the first branched optical path BOP1.

[0064] In the image display device 20, for example, a mirror 301 is arranged in front of the optical fiber 901 on the first branched optical path BOP1, and a mirror 401 is arranged in the rear thereof, and a second polarizing beam splitter 603 is arranged in the second branched optical path BOP2 in the rear of the first polarizing beam splitter 202. For example, the optical fiber 901 has a multiple loop structure, and between the mirrors 301 and 401, the input end faces the mirror 301, and the output end faces the mirror 401.

[0065] In the image display device 20, the first linearly polarized light obtained by converting the laser light from the light source system 100 by the polarization state variable element 201 is reflected by the first polarizing beam splitter 202 toward the mirror 30, and is then reflected by the mirror 30 toward the incident end of the optical fiber 901. The first linearly polarized light that has bypassed the optical fiber 901 is reflected by the mirror 401 toward the second polarizing beam splitter 603. The first linearly polarized light that has entered the second polarizing beam splitter 603 is reflected by the second polarizing beam splitter 603, passes through the combined optical path of the first and second branched optical paths BOP1 and BOP2, and is reflected toward the deflector 701.

[0066] In the image display device 20, the second linearly polarized light obtained by converting the laser light from the light source system 100 by the polarization state variable element 201 passes through the first polarizing beam splitter, passes through the second branched optical path BOP2, passes through the second polarizing beam splitter 603, and is incident on the deflector 701 via the combined optical path of the first and second branched optical paths BOP1 and BOP2.

[0067] As shown in FIG. 7 , in the image display device 20, the control device 1200 does not have a brightness determination unit 1005, and the branched optical path selection unit 1006 selects either the first or second branched optical path BOP1, BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202, based on a drive signal (a signal that can identify the pixel area to be scanned (displayed) in image information on a frame-by-frame basis) from the deflector control unit 1004, and applies a voltage signal according to the selection to the polarization state variable element 201.

[0068] When the branched optical path selection unit 1006 receives a drive signal from the deflector control unit 1004, it selects the first branched optical path BOP1 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202 when the laser light is modulated in accordance with a first pixel area (e.g., a central pixel area) of the image information in frame units (when the first pixel area is the scanning target (display target)), and selects the second branched optical path BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202 when the laser light is modulated in accordance with a second pixel area (e.g., a peripheral pixel area) of the image information in frame units (when the second pixel area is the scanning target (display target)).

[0069] The optical path length of the laser light passing through the first branched optical path BOP1 is made sufficiently long by the optical fiber 901, and a sufficient time difference occurs in the timing at which the laser light reaches the eye EB compared to the laser light passing through the second branched optical path BOP2. This time difference artificially increases the resolution of the image displayed by the laser light passing through the first branched optical path BOP1, and is expected to improve image quality (improve visibility).

[0070] It is preferable that the time difference be a half pixel. For example, if the frame rate is 60 Hz and the resolution is 1980×1080, the laser light source 101 emits light at approximately 128 MHz. The half pixel time difference is 1 / 256×10 -6 (See FIG. 9 ), which corresponds to a frequency of 256 MHz. The occurrence of a time difference of 1 / 2 pixel means that new light emission appears between the emissions of the laser light source 101, which emits light at a light emission frequency of 128 MHz. The time difference is 1 / 256×10 -6 The optical path difference corresponding to the speed of light is 300 x 10 6 m / s, which is about 1.2 m. To generate this optical path difference, an optical fiber 901 is used.

[0071] (Operation of Image Display Device) Hereinafter, the operation of the image display device 20 will be described with reference to Fig. 8. The flowchart in Fig. 8 is based on a processing algorithm executed by the control device 1200. The operation of the image display device 20 indicates an image display method using the image display device 20.

[0072] In the first step S11, the image information input unit 1002 sequentially inputs image information (image data) transmitted from the external device 2000, transmits an input timing signal to the display control unit 1001 for each input, and sequentially transmits the input image information to the modulation signal generation unit 1003.

[0073] In the next step S12, the branch optical path selection unit 1006 determines whether or not to display the first pixel region of the image information in units of frames, i.e., whether to display the first pixel region or the second pixel region of the image information in units of frames, based on the drive signal from the deflector control unit 1004. If the determination here is affirmative, the process proceeds to step S13, and if negative, the process proceeds to step S14.

[0074] In step S13, the branched optical path selection unit 1006 selects the first branched optical path BOP1 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202. Specifically, the branched optical path selection unit 1006 applies a first voltage signal to the polarization state varying element 201 to convert the laser light from the light source system 100 into first linearly polarized light. After step S13 is executed, the process proceeds to step S15.

[0075] In step S14, the branched optical path selection unit 1006 selects the second branched optical path BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202. Specifically, the branched optical path selection unit 1006 applies a second voltage signal to the polarization state varying element 201 to convert the laser light from the light source system 100 into second linearly polarized light. After step S14 is executed, the process proceeds to step S15.

[0076] In step S15, the display control unit 1001 drives the laser light source 101 and the deflector 701 in accordance with the image information. Specifically, the display control unit 1001 transmits a synchronization control signal to the modulation signal generation unit 1003 and the deflector control unit 1004. The modulation signal generation unit 1003 receives the synchronization control signal and generates a modulation signal in accordance with the image information, and applies the modulation signal to the light source drive unit 102. At this time, light modulated in accordance with the image information is emitted from the laser light source 101. The deflector control unit 1004 receives the synchronization control signal and generates a drive signal for driving the deflector 701, and applies the drive signal to the deflector 701. At this time, the deflector 701 performs a laser beam scanning operation.

[0077] In step S16, the display control unit 1001 determines whether or not to end the process. This determination is affirmative, for example, when the image display device 20 is turned off, and negative when it remains on. If the determination in step S16 is affirmative, the flow ends, and if negative, the flow returns to step S11.

[0078] (Effects of the Image Display Device) The effects of the image display device 20 will be described below.

[0079] In the image display device 20, the first optical processing system includes an optical fiber 901 that diverts the laser light traveling along the first branched optical path BOP1. The branched optical path selection system 200 selects the first branched optical path BOP1 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202 when the laser light is modulated in accordance with a first pixel region (e.g., a central pixel region) of the image information in frame units, and selects the second branched optical path BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202 when the laser light is modulated in accordance with a second pixel region (e.g., a peripheral pixel region) of the image information in frame units.

[0080] In this case, with a simple configuration, the resolution of the image corresponding to the first pixel region of the frame-by-frame image information can be made substantially higher than the resolution of the image corresponding to the second pixel region, thereby improving the visibility of the image corresponding to the first pixel region.

[0081] The branched optical path selection system 200 may alternately select the first branched optical path BOP1 and the second branched optical path BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202 for at least one frame (N frames, where N is a natural number). This allows the optical path along which the laser light travels to be switched every N frames, thereby increasing the resolution in an interlaced manner. In this case, the response frequency of the branched optical path selection unit 1006 is equivalent to N times the frame rate.

[0082] Furthermore, by converting the laser light from the light source system 100 into 45-degree linearly polarized or circularly polarized light by the polarization state variable element 201 and making it incident on the first polarizing beam splitter 202, it is possible to simultaneously select both the first and second branched optical paths BOP1 and BOP2 as the optical path along which the laser light travels, thereby doubling the resolution in every frame.

[0083] 3. Image display device according to Example 3 of an embodiment of the present technology> (Configuration of image display device) An image display device according to Example 3 of an embodiment of the present technology will be described with reference to the drawings. Fig. 10 is a diagram showing the configuration of an image display device 30 according to Example 3 of an embodiment. Fig. 11 is a block diagram showing functions of the image display device 30 according to Example 3 of an embodiment.

[0084] As shown in FIG. 10, the image display device 30 has a configuration that combines a part of the image display device 10 according to the first embodiment and a part of the image display device 20 according to the second embodiment.

[0085] In the image display device 30, a part of the image display device 20 is arranged in the front stage, and a part of the image display device 10 is arranged in the rear stage. In the image display device 30, the identifier "-1" is added to the end of the reference numerals indicating the same components as those of the image display device 10, and the identifier "-2" is added to the end of the reference numerals indicating the same components as those of the image display device 20.

[0086] The image display device 30 includes, at the front stage, a light source system 100, a first polarization state varying element 201-1, a first polarizing beam splitter 202-1, a mirror 301-1, an optical fiber 901, a mirror 401-1, and a second polarizing beam splitter 603-1.

[0087] In the image display device 30, the branched optical path selection system 200-1 selects at least one of the first and second branched optical paths BOP1 and BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202-1.

[0088] The image display device 30 includes, downstream of the second polarizing beam splitter 603-1, a second polarization state variable element 201-2, a first polarizing beam splitter 202-2, a mirror 301-2, an optical attenuation unit 501, a half-wave plate 601, a mirror 401-2, a half-wave plate 602, a second polarizing beam splitter 603-2 (optical path synthesis unit), a deflector 701, and an eyepiece 801.

[0089] In the image display device 30, the branched optical path selection system 200-2 selects one of the third and fourth branched optical paths BOP3 and BOP4 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202-2. On the third branched optical path BOP3, a mirror 301, an optical attenuator 501, and a half-wave plate 601 are arranged in this order from the first polarizing beam splitter 202-2 side to the second polarizing beam splitter 603-2 side. On the fourth branched optical path BOP4, a mirror 401-2 and a half-wave plate 602 are arranged in this order from the first polarizing beam splitter 202-2 side to the second polarizing beam splitter 603-2 side.

[0090] In the image display device 30 , a control device 1300 controls the light source system 100 , the first and second polarization state varying elements 201 - 1 and 201 - 2 , and the deflector 701 .

[0091] As shown in FIG. 11, the control device 1300 has a first branched optical path selection unit 1006-1 that controls the first polarization state variable element 201-1, and a second branched optical path selection unit 1006-2 that controls the second polarization state variable element 201-2.

[0092] (Operation of Image Display Device) Hereinafter, the operation of the image display device 30 will be described with reference to Fig. 12. The flowchart in Fig. 12 is based on a processing algorithm executed by the control device 1300. The operation of the image display device 30 also constitutes an image display method using the image display device 30.

[0093] In the first step S21, the image information input unit 1002 sequentially inputs image information (image data) transmitted from the external device 2000, transmits an input timing signal to the display control unit 1001 for each input, and sequentially transmits the input image information to the modulation signal generation unit 1003 and the brightness determination unit 1005.

[0094] In the next step S22, the first branch optical path selection unit 1006-1 determines whether or not to display the first pixel region of the image information in units of frames, i.e., whether to display the first pixel region or the second pixel region of the image information in units of frames, based on the drive signal from the deflector control unit 1004. If the determination here is affirmative, the process proceeds to step S23, and if negative, the process proceeds to step S24.

[0095] In step S23, the first branched optical path selection unit 1006-1 selects the first branched optical path BOP1 as the branched optical path along which the laser light (e.g., linearly polarized light) travels from the first polarizing beam splitter 202-1. Specifically, the first branched optical path selection unit 1006-1 applies a first voltage signal to the first polarization state varying element 201-1 to convert the laser light from the light source system 100 into first linearly polarized light. After step S23 is executed, the process proceeds to step S25.

[0096] In step S24, the first branched optical path selection unit 1006-1 selects the second branched optical path BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202-1. Specifically, the first branched optical path selection unit 1006-1 applies a second voltage signal to the first polarization state varying element 201-1 to convert the laser light from the light source system 100 into second linearly polarized light. After step S24 is executed, the process proceeds to step S25.

[0097] In step S25, the brightness determination unit 1005 determines whether the brightness of the image information is within the first brightness range (low brightness range), i.e., whether the brightness of the image information is within the first brightness range or the second brightness range (high brightness range). If the determination here is affirmative, the process proceeds to step S26, and if negative, the process proceeds to step S27.

[0098] In step S26, the second branched optical path selection unit 1006-2 selects the third branched optical path BOP3 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202-2. Specifically, the second branched optical path selection unit 1006-2 applies a first voltage signal to the second polarization state varying element 201-2 to convert the second linearly polarized light from the second polarizing beam splitter 603-1 into the first linearly polarized light (to pass the first linearly polarized light as is). After step S26 is executed, the process proceeds to step S28.

[0099] In step S27, the second branched optical path selection unit 1006-2 selects the fourth branched optical path BOP4 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202-2. Specifically, the second branched optical path selection unit 1006-2 applies a second voltage signal to the second polarization state varying element 201-2 to convert the first linearly polarized light from the second polarizing beam splitter 603-1 into the second linearly polarized light (to pass the second linearly polarized light as is). After step S27 is executed, the process proceeds to step S28.

[0100] In step S28, the display control unit 1001 drives the laser light source 101 and the deflector 701 in accordance with the image information. Specifically, the display control unit 1001 transmits a synchronization control signal to the modulation signal generation unit 1003 and the deflector control unit 1004. The modulation signal generation unit 1003 receives the synchronization control signal and generates a modulation signal in accordance with the image information, and applies the modulation signal to the light source drive unit 102. At this time, light modulated in accordance with the image information is emitted from the laser light source 101. The deflector control unit 1004 receives the synchronization control signal and generates a drive signal for driving the deflector 701, and applies the drive signal to the deflector 701. At this time, the deflector 701 performs a laser beam scanning operation.

[0101] In the final step S29, the display control unit 1001 determines whether or not to end the process. This determination is affirmative, for example, when the image display device 30 is turned off, and negative when it remains on. If the determination in step S29 is affirmative, the flow ends, and if negative, the flow returns to step S21.

[0102] (Effects of the Image Display Device) The effects of the image display device 30 will be described below.

[0103] The image display device 30 comprises: a light source system 100 including at least one laser light source 101 and emitting laser light modulated in accordance with image information; a branched optical path selection system 200-1 including a first polarizing beam splitter 202-1 that branches the optical path of the laser light from the light source system 100 into first and second branched optical paths BOP1 and BOP2; and an optical path synthesis system 600-1 including a second polarizing beam splitter 603-1 that synthesizes the first and second branched optical paths BOP1 and BOP2, wherein the branched optical path selection system 200-1 selects at least one of the first and second branched optical paths BOP1 and BOP2 as the branched optical path along which the laser light travels from the first polarizing beam splitter 202, and further comprises an optical fiber 901 as a first optical processing system that performs optical processing on the laser light traveling along the first branched optical path BOP1 of the first and second branched optical paths BOP1 and BOP2.

[0104] The image display device 30 further comprises a branched optical path selection system 200-2 including a first polarizing beam splitter 202-2 that branches the optical path formed by the combination of the first and second branched optical paths BOP1, BOP2 in the optical path combination system 600-1 into third and fourth branched optical paths BO3, BO4, and an optical path combination system 600-2 including a second polarizing beam splitter 603-2 that combines the third and fourth branched optical paths BO3, BO4. The branched optical path selection system 200-2 selects either the third or fourth branched optical paths BOP1, BOP2 as another branched optical path along which the laser light travels from the first polarizing beam splitter 202-2 based on image information, and further comprises an optical attenuation unit 501 as a second optical processing system that performs optical processing on the laser light traveling along the third branched optical path BO3 of the third and fourth branched optical paths BO3, BO4.

[0105] According to the image display device 30, it is possible to obtain both the effects of the image display device 10 according to the first embodiment and the effects of the image display device 20 according to the second embodiment.

[0106] In the image display device 30, a part of the image display device 10 may be arranged in the front stage, and a part of the image display device 20 may be arranged in the rear stage.

[0107] In the image display device 30, the light source system 100 has a single laser light source 101, but may also have, for example, a laser light source that emits red laser light, a laser light source that emits green laser light, and a laser light source that emits blue laser light, and emit colored light that is a combination of the laser light from these laser light sources.

[0108] 4. Image display device according to Example 4 of an embodiment of the present technology> (Configuration of image display device) An image display device according to Example 4 of an embodiment of the present technology will be described with reference to the drawings. Fig. 13 is a diagram showing the configuration of an image display device 40 according to Example 4 of an embodiment. Fig. 14 is a block diagram showing functions of the image display device 40 according to Example 4 of an embodiment.

[0109] Generally, the threshold currents of the laser light sources emitting red, green, and blue laser beams are different. Therefore, when attenuating a colored light obtained by combining red, green, and blue laser beams, each colored laser beam is attenuated uniformly, resulting in significant color variation in the low brightness range depending on the temperature conditions and gradation. As will be described in detail below, the image display device 40 has a configuration that can address this problem and can obtain high-definition, high-dynamic-range images.

[0110] As shown in Figures 13 and 14, the image display device 40 has a portion of the image display device 10 according to Example 1 in the front stage for each of the RGB colors, and a portion of the image display device 20 according to Example 2 in the rear stage.

[0111] The image display device 40 has multiple (e.g., three) laser light sources 101R, 101G, and 101B with different emission wavelengths, and a branched optical path selection system, an optical path combining system, and a first optical processing system (light attenuation unit 501) are provided for each laser light source. The laser light source 101R has an emission wavelength in the red band. The laser light source 101G has an emission wavelength in the green band. The laser light source 101B has an emission wavelength in the blue band. The light attenuation units 501 provided for each laser light source may have different light attenuation rates.

[0112] A light source driving unit 102 is shared by a light source system 100R including the laser light source 101R, a light source system 100G including the laser light source 101G, and a light source system 100B including the laser light source 101B.

[0113] The modulation signal generation unit 1003 generates a modulation signal for modulating and driving the laser light source 101R, a modulation signal for modulating and driving the laser light source 101G, and a modulation signal for modulating and driving the laser light source 101B based on color image information output from the external device 2000 via the image information input unit 1002, and applies each modulation signal to the light source drive unit 102. The light source drive unit 102 generates a drive current to be applied to the corresponding laser light source based on each modulation signal.

[0114] In the image display device 40, the control device 1400 has a brightness determination unit 1005R, a branched optical path selection unit 1006R, and a polarization state variable element 201R corresponding to the laser light source 101R, a brightness determination unit 1005G, a branched optical path selection unit 1006G, and a polarization state variable element 201G corresponding to the laser light source 101G, and a brightness determination unit 1005B, a branched optical path selection unit 1006B, and a polarization state variable element 201B corresponding to the laser light source 101B.

[0115] The image display device 40 also has a mirror 951, a mirror 952, a dichroic mirror 953, and a dichroic mirror 954. The dichroic mirror 953 reflects green light and transmits blue light, combining the optical paths of the green light and blue light. The dichroic mirror 954 reflects red light and transmits green light and blue light, combining the optical paths of the red light, green light, and blue light.

[0116] The laser light (red light) emitted from the second polarizing beam splitter 603 corresponding to the light source system 100R is reflected by the mirror 951 toward the dichroic mirror 954, and then reflected by the dichroic mirror 954 toward the polarization state variable element 201.

[0117] The laser light (green light) emitted from the second polarizing beam splitter 603 corresponding to the light source system 100G is reflected by the mirror 952 toward the dichroic mirror 953, reflected by the dichroic mirror 953 toward the dichroic mirror 954, and transmitted through the dichroic mirror 954 toward the polarization state variable element 201.

[0118] The laser light (blue light) emitted from the second polarizing beam splitter 603 corresponding to the light source system 100B passes through the dichroic mirror 953 toward the dichroic mirror 954, and then passes through the dichroic mirror 954 toward the polarization state variable element 201.

[0119] Each color light beam incident on the polarization state variable element 201 passes through at least one branched optical path selected by the branched optical path selection system 200, and is then incident on the deflector 701 via the second polarizing beam splitter 603. Each color light beam incident on the deflector 701 is subjected to a laser beam scanning operation on the eyeball EB via the eyepiece 801.

[0120] 5. Image display device according to Example 5 of an embodiment of the present technology An image display device 50 according to Example 5 of an embodiment of the present technology will be described with reference to the drawings. Fig. 15 is a diagram showing the configuration of the image display device 50 according to Example 5 of an embodiment. Fig. 16 is a block diagram showing the functions of the image display device 50 according to Example 5 of an embodiment.

[0121] As shown in FIGS. 15 and 16, the image display device 50 has a digital mirror device (DMD) 203 as an optical path branching unit.

[0122] The digital mirror device 203 is an element having multiple micromirrors (pixels) arranged two-dimensionally (e.g., in a matrix or staggered arrangement) on a substrate and rotatable (position-changeable) relative to the substrate. The digital mirror device 203 is arranged so that laser light from the light source system 100 is obliquely incident with respect to the normal direction (hereinafter simply referred to as the "normal direction") of the substrate surface. When the digital mirror device 203 is turned on, each micromirror is rotated from a reference position (OFF position) parallel to the substrate surface to an ON position, and the obliquely incident laser light is reflected by the micromirror in the normal direction. The reflected laser light travels along the first branched optical path BOP1, is attenuated by the optical attenuation unit 501, is reflected by the mirror 301, and is incident on the half mirror 604, which serves as an optical path combining unit. When the digital mirror device 203 is turned off, each micromirror is maintained in the reference position (OFF position), and the obliquely incident laser light is reflected by the micromirror in a direction oblique to the normal direction. The reflected laser light travels along a second branched optical path BOP 2 and is incident on a half mirror 604 .

[0123] The laser light that passes through the first branched optical path BOP1 and the half mirror 604 and the laser light that passes through the second branched optical path BOP2 and is reflected by the half mirror 604 pass through the same optical path (synthetic optical path), are deflected by the deflector 701, and are incident on the eyeball EB via the eyepiece 801.

[0124] Digital mirror device 203 is controlled by control device 1100 (see FIG. 16 ). Specifically, when branch optical path selection unit 1006 selects first branch optical path BOP1 in accordance with the determination result of brightness determination unit 1005, it sets a mirror drive signal for driving micromirrors in digital mirror device 203 corresponding to each pixel of the image information to high level, putting the micromirrors in the ON position, and when it selects second branch optical path BOP2, it sets a mirror drive signal for driving micromirrors in digital mirror device 203 corresponding to each pixel of the image information to low level, putting the micromirrors in the OFF position.

[0125] Here, the optical system is laid out so that the laser light that has traveled through the first branched optical path BOP1 is transmitted by the half mirror 604 and the laser light that has traveled through the second branched optical path BOP2 is reflected by the half mirror 604, but the optical system may also be laid out so that the laser light that has traveled through the first branched optical path BOP1 is reflected by the half mirror 604 and the laser light that has traveled through the second branched optical path BOP2 is transmitted by the half mirror 604. Also, a configuration in which the light attenuating unit 501 is disposed on the second branched optical path BOP2 may be employed.

[0126] 5.5 Image display device according to a modified example of Example 5 of an embodiment of the present technology An image display device according to a modified example of Example 5 of an embodiment of the present technology will be described with reference to the drawings. Fig. 17 is a diagram showing the configuration of an image display device 55 according to a modified example of Example 5 of an embodiment.

[0127] As shown in FIG. 17, the image display device 55 has an optical path combining system 600 that includes a polarizing beam splitter 605 as an optical path combining section and a half-wave plate 602 disposed on the second branched optical path BOP2.

[0128] In the image display device 55, the light source system 100 emits first linearly polarized light (laser light) whose polarization direction is a predetermined direction. The first linearly polarized light that travels from the digital mirror device 203 to the first branched optical path BOP1 is attenuated by the optical attenuation unit 501, reflected by the mirror 301, transmitted through the polarizing beam splitter 605, and incident on the deflector 701. The first linearly polarized light that travels from the digital mirror device 203 to the second branched optical path BOP2 is converted by the half-wave plate 602 into second linearly polarized light whose polarization direction is orthogonal to that of the first linearly polarized light. The second linearly polarized light is reflected by the polarizing beam splitter 605 and incident on the deflector 701.

[0129] The laser light that has passed through the polarizing beam splitter 605 via the first branched optical path BOP1 and the laser light that has passed through the second branched optical path BOP2 and is reflected by the polarizing beam splitter 605 pass through the same optical path (synthetic optical path), are deflected by the deflector 701, and are incident on the eyeball EB via the eyepiece 801.

[0130] According to the image display device 55, the optical path combining system 600 is made up of the polarizing beam splitter 605 and the half-wave plate 602, so although the configuration is somewhat complicated, loss of light quantity is suppressed.

[0131] 6. Image display device according to Example 6 of an embodiment of the present technology An image display device according to Example 6 of an embodiment of the present technology will be described with reference to the drawings. Fig. 18 is a diagram showing the configuration of an image display device 60 according to Example 6 of an embodiment. Fig. 19 is a block diagram showing the functions of the image display device 60 according to Example 6 of an embodiment.

[0132] As shown in FIGS. 18 and 19 , the image display device 60 has a reflective liquid crystal grating 4000 (liquid crystal grating) as an optical path branching section. The reflective liquid crystal grating 4000 is an element having a plurality of liquid crystals (pixels) arranged two-dimensionally. The reflective liquid crystal grating 4000 diffracts and reflects incident light (laser light) when ON and transmits the incident light (laser light) as is when OFF. The laser light diffracted and reflected by the reflective liquid crystal grating 4000 travels along a first branched optical path BOP1 and is incident on a dispersion-compensating reflective grating 4500 (diffraction element). The dispersion-compensating reflective grating 4500 is composed of a reflective grating having the same grating pitch as the reflective liquid crystal grating 4000. The dispersion-compensating reflective grating 4500 compensates for the angle shift due to wavelength dispersion when the light is diffracted and reflected by the reflective liquid crystal grating 4000, and diffracts and reflects the incident light at the same diffraction angle as the diffraction angle of the laser light diffracted and reflected by the reflective liquid crystal grating 4000. The laser light diffracted and reflected by the dispersion compensating reflective grating 4500 is attenuated by the light attenuating section 501 and incident on the half mirror 604. The laser light transmitted through the reflective liquid crystal grating 4000 is reflected by the mirror 401 and incident on the half mirror 604.

[0133] The laser light that passes through the first branched optical path BOP1 and the half mirror 604 and the laser light that passes through the second branched optical path BOP2 and is reflected by the half mirror 604 travel along the same optical path (synthetic optical path), are deflected by the deflector 701, and are incident on the eyeball EB via the eyepiece 801.

[0134] The reflective liquid crystal grating 4000 is controlled by the control device 1100 (see FIG. 19 ). Specifically, when the branch optical path selection unit 1006 selects the first branch optical path BOP1 in accordance with the determination result of the brightness determination unit 1005, it sets a liquid crystal drive signal for driving the liquid crystal of the reflective liquid crystal grating 4000 corresponding to each pixel of the image information to a high level, thereby turning the liquid crystal into an ON state (diffraction reflection state), and when it selects the second branch optical path BOP2, it sets a liquid crystal drive signal for driving the liquid crystal of the reflective liquid crystal grating 4000 corresponding to each pixel of the image data to a low level, thereby turning the liquid crystal into an OFF state (transmission state).

[0135] Here, the optical system is laid out so that the laser light that has traveled through the first branched optical path BOP1 is transmitted by the half mirror 604 and the laser light that has traveled through the second branched optical path BOP2 is reflected by the half mirror 604, but the optical system may also be laid out so that the laser light that has traveled through the first branched optical path BOP1 is reflected by the half mirror 604 and the laser light that has traveled through the second branched optical path BOP2 is transmitted by the half mirror 604. Also, a configuration in which the light attenuating unit 501 is disposed on the second branched optical path BOP2 may be employed.

[0136] 6.5 Image display device according to a modified example of Example 6 of an embodiment of the present technology An image display device according to a modified example of Example 6 of an embodiment of the present technology will be described with reference to the drawings. Fig. 20 is a diagram showing the configuration of an image display device 65 according to a modified example of Example 6 of an embodiment.

[0137] As shown in FIG. 20, the image display device 65 has an optical path combining system 600 that includes a polarizing beam splitter 605 as an optical path combining section, and a half-wave plate 602 disposed on the second branched optical path BOP2.

[0138] In the image display device 65, the light source system 100 emits first linearly polarized light (laser light) having a predetermined polarization direction. The first linearly polarized light is diffracted and reflected by the reflective liquid crystal grating 4000 and travels to the first branched optical path BOP1, where it is diffracted and reflected by the dispersion-compensating reflective grating 4500, attenuated by the optical attenuation unit 501, transmitted through the polarizing beam splitter 605, and incident on the deflector 701. The first linearly polarized light is transmitted through the reflective liquid crystal grating 4000 and travels to the second branched optical path BOP2, where it is reflected by the mirror 401 and converted by the half-wave plate 602 into second linearly polarized light whose polarization direction is orthogonal to that of the first linearly polarized light. The second linearly polarized light is reflected by the polarizing beam splitter 605 and incident on the deflector 701.

[0139] The laser light that passes through the first branched optical path BOP1 and is transmitted through the polarizing beam splitter 605 and the laser light that passes through the second branched optical path BOP2 and is reflected by the polarizing beam splitter 605 pass through the same optical path (synthetic optical path), are deflected by the deflector 701, and are incident on the eyeball EB via the eyepiece 801.

[0140] According to the image display device 65, the optical path combining system 600 is made up of the polarizing beam splitter 605 and the half-wave plate 602, so although the configuration is somewhat complicated, loss of light quantity is suppressed.

[0141] 7. Image display device according to Example 7 of an embodiment of the present technology An image display device according to Example 7 of an embodiment of the present technology will be described with reference to the drawings. Fig. 21 is a diagram showing the configuration of an image display device 70 according to Example 7 of an embodiment. Fig. 22 is a block diagram showing functions of the image display device 70 according to Example 7 of an embodiment.

[0142] As shown in FIGS. 21 and 22 , the image display device 70 has a transmissive liquid crystal grating 5000 (liquid crystal grating) as an optical path branching section. The transmissive liquid crystal grating 5000 is an element having a plurality of two-dimensionally arranged liquid crystals (pixels). The transmissive liquid crystal grating 5000 diffracts and transmits incident light (laser light) when ON and transmits the incident light (laser light) as is when OFF. The laser light diffracted and transmitted by the transmissive liquid crystal grating 5000 travels along a first branched optical path BOP1 and is incident on a dispersion-compensating transmission grating 5500 (diffraction element). The dispersion-compensating transmission grating 5500 is a transmission grating having the same grating pitch as the transmissive liquid crystal grating 5000. The dispersion-compensating transmission grating 5500 compensates for the angle shift caused by wavelength dispersion when the incident light is diffracted and transmitted by the transmissive liquid crystal grating 5000, and diffracts and transmits the incident light at the same diffraction angle as the diffraction angle of the laser light diffracted and reflected by the transmissive liquid crystal grating 5000. The laser light diffracted and transmitted by the dispersion compensating transmission grating 5500 is attenuated by the light attenuating section 501 and is incident on the half mirror 604. The laser light transmitted through the transmission type liquid crystal grating 5000 is reflected by the mirror 401 and is incident on the half mirror 604.

[0143] The laser light that passes through the first branched optical path BOP1 and is transmitted through the half mirror 604 and the laser light that passes through the second branched optical path BOP2 and is reflected by the half mirror 604 pass through the same optical path (synthetic optical path), are deflected by the deflector 701, and are incident on the eyeball EB via the eyepiece 801.

[0144] The transmissive liquid crystal grating 5000 is controlled by the control device 1100 (see FIG. 22 ). Specifically, when the branch optical path selection unit 1006 selects the first branch optical path BOP1 in accordance with the determination result of the brightness determination unit 1005, it sets a liquid crystal drive signal for driving the liquid crystal of the transmissive liquid crystal grating 5000 corresponding to each pixel of the image information to a high level, thereby turning the liquid crystal into an ON state (diffraction transmission state), and when it selects the second branch optical path BOP2, it sets a liquid crystal drive signal for driving the liquid crystal of the transmissive liquid crystal grating 5000 corresponding to each pixel of the image information to a low level, thereby turning the liquid crystal into an OFF state (transmission state).

[0145] Here, the optical system is laid out so that the laser light that has traveled through the first branched optical path BOP1 is transmitted by the half mirror 604 and the laser light that has traveled through the second branched optical path BOP2 is reflected by the half mirror 604, but the optical system may also be laid out so that the laser light that has traveled through the first branched optical path BOP1 is reflected by the half mirror 604 and the laser light that has traveled through the second branched optical path BOP2 is transmitted by the half mirror 604. Also, a configuration in which the light attenuating unit 501 is disposed on the second branched optical path BOP2 may be employed.

[0146] 7.5 Image display device according to a modified example of Example 7 of an embodiment of the present technology An image display device according to a modified example of Example 7 of an embodiment of the present technology will be described with reference to the drawings. Fig. 23 is a diagram showing the configuration of an image display device 75 according to a modified example of Example 7 of an embodiment.

[0147] As shown in FIG. 23, the image display device 75 has an optical path combining system 600 that includes a polarizing beam splitter 605 as an optical path combining section and a half-wave plate 602 disposed on the second branched optical path BOP2.

[0148] In the image display device 75, the light source system 100 emits first linearly polarized light (laser light) having a predetermined polarization direction. The first linearly polarized light is diffracted and transmitted by the transmission liquid crystal grating 5000 and travels to the first branched optical path BOP1, where it is diffracted and transmitted by the dispersion-compensating transmission grating 5500, attenuated by the light attenuation unit 501, transmitted through the polarizing beam splitter 605, and incident on the deflector 701. The first linearly polarized light is transmitted through the transmission liquid crystal grating 5000 and travels to the second branched optical path BOP2, where it is converted by the half-wave plate 602 into second linearly polarized light whose polarization direction is orthogonal to that of the first linearly polarized light. The second linearly polarized light is reflected by the mirror 401, reflected by the polarizing beam splitter 605, and incident on the deflector 701.

[0149] The laser light that has passed through the polarizing beam splitter 605 via the first branched optical path BOP1 and the laser light that has passed through the second branched optical path BOP2 and is reflected by the polarizing beam splitter 605 pass through the same optical path (synthetic optical path), are deflected by the deflector 701, and are incident on the eyeball EB via the eyepiece 801.

[0150] According to the image display device 75, the optical path combining system 600 is composed of the polarizing beam splitter 605 and the half-wave plate 602, so although the configuration is somewhat complicated, loss of light quantity is suppressed.

[0151] 8. Modifications of the Present Technology The configuration of the image display device in each of the embodiments of the present technology described above can be modified as appropriate.

[0152] For example, as in an image display device 15 according to a modified example of the first embodiment shown in Fig. 24, the optical system may be laid out so that the optical path length of the first branched optical path BOP1 is longer than the optical path length of the second branched optical path BOP2, and the optical attenuation unit 501 may be arranged on the first branched optical path BOP1. Note that in the layout of the optical system in Fig. 15, the optical attenuation unit 501 may be arranged on the second branched optical path BOP2.

[0153] Recently, a technology called foveated rendering has emerged that creates an image by increasing the resolution only of the area corresponding to the fovea, where the optic nerve of the retina is concentrated (the area on the screen where the user is gazing). By increasing the resolution only by an angle of view of approximately ±10 degrees from the fovea, it becomes possible to display only the desired portion of a high-definition image. With foveated rendering, by switching the optical path or using both optical paths only for the area where the resolution is increased, it becomes possible to display an image with improved definition.

[0154] For example, as in an image display device according to a modified example of Example 2 shown in Fig. 25 , the branched optical path selection unit 1006 may select a branched optical path based on the drive signal of the deflector 701 and the detection result of the gaze detection device 3000 (eye tracking device). Specifically, for example, a first pixel region of the image information in units of frames may be set as a gaze region including the user's gaze direction, and a second pixel region of the image information may be set as a peripheral region surrounding the gaze region. This may substantially increase the resolution of the user's gaze region, thereby improving the visibility of the image.

[0155] The gaze detection device 3000 may be provided on the eyeglass frame serving as the support structure. The gaze detection device 3000 detects the gaze, which is the direction of the user's eyeball EB, and outputs the detection result to the branched optical path selection unit 1006. The gaze detection device 3000 includes, for example, a light-receiving / emitting unit and a signal processing unit that processes an output signal from the light-receiving / emitting unit. The light-receiving / emitting unit includes a light-emitting element that irradiates the eyeball EB with invisible light (e.g., infrared light) and a light-receiving element that receives light emitted from the light-emitting element and reflected by the eyeball EB. The light-receiving element may be, for example, a photodiode, a segmented photodiode with multiple light-receiving areas, an image sensor, or an event-type sensor (eye sensing sensor). The signal processing unit processes the output signal from the light-receiving element and calculates the gaze direction. A gaze guidance device may be provided in addition to or instead of the gaze detection device. The gaze guidance device may guide the gaze visually by displaying arrows, letters, etc. indicating the gaze destination within the displayed image, or may guide the gaze auditorily by using sound, etc.

[0156] For example, as shown in Figure 26, an image display device 45 according to a modified example of Example 4 may have a configuration in which the optical system from the polarization state variable element 201 to the second polarizing beam splitter 603 is omitted from the image display device 40 according to Example 4.

[0157] The optical path branching section may be a movable mirror (mechanically rotating a reflecting mirror), an acousto-optic element (AO element), or the like.

[0158] The detouring portion is not limited to an optical fiber, but may be anything that extends the optical path length of the laser light, and may be, for example, a high refractive index medium.

[0159] At least a part of the configurations of the above-described embodiments and modifications may be combined with each other to the extent that no contradiction occurs.

[0160] The present technology may also be configured as follows: (1) An image display device comprising: a light source system including at least one laser light source and emitting laser light modulated according to image information; a branched optical path selection system including an optical path branching unit that branches an optical path of the laser light from the light source system into a plurality of branched optical paths; and an optical path combining system that combines the plurality of branched optical paths, wherein the branched optical path selection system selects at least one of the plurality of branched optical paths as the branched optical path along which the laser light from the optical path branching unit travels; and further comprising: a first optical processing system that performs optical processing on the laser light traveling along some of the plurality of branched optical paths. (2) The image display device according to (1), wherein the branched optical path selection system makes the selection based on the image information. (3) The image display device according to (1) or (2), wherein the intensity of excitation of the laser light source in the light source system exceeds an oscillation threshold, and the first optical processing system includes an optical attenuation unit that attenuates the laser light traveling along some of the branched optical paths. (4) The image display device according to any one of (1) to (3), wherein the branched optical path selection system selects the part of the branched optical paths as the branched optical paths along which the laser light travels from the optical path branching unit when the luminance of the image information is within a first luminance range equal to or less than a predetermined value, and selects another part of the branched optical paths as the branched optical paths along which the laser light travels from the optical path branching unit when the luminance of the image information is within a second luminance range above the predetermined value. (5) The image display device according to any one of (1) to (4), wherein the first optical processing system includes a detouring unit that detouring the laser light traveling through the part of the branched optical paths. (6) The image display device described in (5), wherein the branched optical path selection system selects one of the branched optical paths as the branched optical path along which the laser light travels from the optical path branching unit when the laser light is modulated according to a first pixel region of the image information on a frame-by-frame basis, and selects another of the plurality of branched optical paths as the branched optical path along which the laser light travels from the optical path branching unit when the laser light is modulated according to a second pixel region of the image information on a frame-by-frame basis.(7) The image display device according to (5) or (6), wherein the branched optical path selection system alternately selects the part of the branched optical paths as the branched optical path along which the laser beam travels from the optical path branching unit and selects other branched optical paths from the plurality of branched optical paths at least every one frame. (8) The image display device according to any one of (1) to (7), further comprising: an another branched optical path selection system including an another optical path branching unit that branches the optical path combined from the plurality of branched optical paths by the optical path combining system into a plurality of other branched optical paths; and an another optical path combining system that combines the plurality of other branched optical paths, wherein the another branched optical path selection system selects at least one other branched optical path from the plurality of other branched optical paths as the other branched optical path along which the laser beam travels from the other optical path branching unit based on the image information, and further comprises a second optical processing system that performs optical processing on the laser beam traveling along some of the plurality of other branched optical paths. (9) The image display device according to (8), wherein the intensity of excitation of the laser light source in the light source system exceeds an oscillation threshold, and the second optical processing system includes an optical attenuation unit that attenuates the laser light traveling along the some of the other branched optical paths. (10) The image display device according to (8) or (9), wherein the other branched optical path selection system selects the some of the other branched optical paths as the other branched optical path along which the laser light travels from the other optical path branching unit when the brightness of the image information is within a first brightness range that is equal to or less than a predetermined value, and selects another other branched optical path from the other optical path branching unit as the other branched optical path along which the laser light travels from the other optical path branching unit when the brightness of the image information is within a second brightness range that is greater than the predetermined value. (11) The image display device according to any one of (8) to (10), wherein the second optical processing system includes a detouring unit that detouring the laser light traveling along the some of the other branched optical paths.(12) The image display device according to (11), wherein the another branched optical path selection system selects the part of the another branched optical path as the another branched optical path along which the laser light propagates from the another optical path branching unit when the laser light is modulated in accordance with a first pixel region of the image information on a frame-by-frame basis, and selects another part of the other branched optical path among the plurality of another branched optical paths as the another branched optical path along which the laser light propagates from the another optical path branching unit when the laser light is modulated in accordance with a second pixel region of the image information on a frame-by-frame basis. (13) The image display device according to (11) or (12), wherein the another branched optical path selection system alternately selects the part of the another branched optical path as the another branched optical path along which the laser light propagates from the another optical path branching unit and selects another part of the other branched optical path among the plurality of another branched optical paths at least for every one frame. (14) The image display device according to any one of (1) to (13), wherein the branched optical path selection system includes a polarization state variable element that can vary the polarization state of the laser light from the light source system, and at least the optical path branching unit among the optical path branching unit and the optical path combining system includes a polarizing beam splitter. (15) The image display device according to any one of (8) to (14), wherein the other branched optical path selection system includes a polarization state variable element that can vary the polarization state of the laser light from the optical path combining system, and at least the other optical path branching unit among the other optical path branching unit and the other optical path combining system includes a polarizing beam splitter. (16) The image display device according to any one of (1) to (15), wherein the at least one laser light source is a plurality of laser light sources having different emission wavelengths, and the branched optical path selection system, the optical path combining system, and the first optical processing system are provided for each of the laser light sources. (17) The image display device according to any one of (1) to (16), wherein the optical path branching unit includes an element in which a plurality of pixels are arranged two-dimensionally. (18) The image display device according to any one of (8) to (17), wherein the other optical path branching unit includes an element in which a plurality of pixels are arranged two-dimensionally.(19) An image display method including: a step of emitting modulated laser light according to image information; a step of selecting at least one of a plurality of branched optical paths as the branched optical path along which the laser light, whose optical path is branched into a plurality of branched optical paths, travels based on the image information; a step of performing a first optical processing on the laser light traveling along the branched optical path when a branched optical path among the plurality of branched optical paths is selected as the branched optical path along which the laser light travels; and a step of combining the plurality of branched optical paths. (20) The image display method according to (19), comprising: a step of selecting at least one of the plurality of other branch optical paths as the other branch optical path along which the laser light propagates, the other branch optical path being branched into a plurality of other branch optical paths by combining the plurality of branch optical paths; when some of the other branch optical paths are selected as the other branch optical path along which the laser light propagates, a step of performing a second optical process on the laser light propagating through the some of the other branch optical paths; and a step of combining the plurality of other branch optical paths. (21) The image display method according to (19) or (20), wherein the first optical process is a light attenuation process or a light detouring process. (22) The image display method according to (20) or (21), wherein the second optical process is a light attenuation process or a light detouring process. (23) The image display device according to any one of (4) to (22), wherein the second luminance range is wider than the first luminance range. (24) The image display device according to any one of (17) to (23), wherein the element is a liquid crystal grating. (25) The image display device according to any one of (17) to (24), wherein the element is a digital mirror device. (26) The image display device according to any one of (17) to (25), wherein the branching optical path selection system includes a diffraction element arranged upstream and / or downstream of the element. (27) The image display device according to any one of (14) to (26), wherein the polarization state variable element includes an electro-optical element. (28) The image display device according to any one of (14) to (27), wherein the polarization state variable element includes a retarder. Liquid crystal element.(29) The image display device according to any one of (1) to (28), wherein the optical path combining system further includes a first retardation element arranged on some of the branched optical paths among the plurality of branched optical paths and a second retardation element arranged on other of the plurality of branched optical paths. (30) The image display device according to any one of (1) to (29), wherein the optical attenuation unit includes an ND (Neutral Density) filter. (31) The image display device according to any one of (1) to (30), wherein the optical attenuation unit includes a diffraction grating.

[0161] 10, 20, 30, 40: Image display device 100: Light source system 101, 101R, 101G, 101B: Laser light source 200: Branched optical path selection system 201: Polarization state variable element 201-1: First polarization state variable element 201-2: Second polarization state variable element 202, 202-1, 202-2: First polarized beam splitter (optical path branching section, polarized beam splitter) 203: Digital mirror device (element) 501: Light attenuation section 600, 600-1, 600-2: Optical path synthesis system 603, 603-1, 603-2: Second polarized beam splitter (polarized beam splitter) 901: Optical fiber (detouring section) 4000: Reflective liquid crystal grating (element) 5000: Transmissive liquid crystal grating (element) BOP1: First branched optical path (branched optical path) BOP2: Second branched optical path (branched optical path) BOP3: Third branched optical path (another branched optical path) BOP4: Fourth branched optical path (another branched optical path)

Claims

1. An image display device comprising: a light source system including at least one laser light source and emitting laser light modulated according to image information; a branching optical path selection system including an optical path branching unit that branches an optical path of the laser light from the light source system into a plurality of branching optical paths; and an optical path combining system that combines the plurality of branching optical paths, wherein the branching optical path selection system selects at least one of the plurality of branching optical paths as the branching optical path through which the laser light travels from the optical path branching unit, and further includes a first optical processing system that performs optical processing on the laser light traveling through a part of the plurality of branching optical paths.

2. The image display device according to claim 1, wherein the branching optical path selection system makes the selection based on the image information.

3. In the light source system, the magnitude of excitation to the laser light source exceeds the oscillation threshold value, and the first optical processing system includes an optical attenuation unit that attenuates the laser light traveling through the part of the branching optical paths. The image display device according to claim 1.

4. The branching optical path selection system selects the part of the branching optical paths as the branching optical path through which the laser light travels from the optical path branching unit when the luminance of the image information is within a first luminance range of a predetermined value or less, and selects another part of the branching optical paths among the plurality of branching optical paths as the branching optical path through which the laser light travels from the optical path branching unit when the luminance of the image information is within a second luminance range exceeding the predetermined value. The image display device according to claim 3.

5. The first optical processing system includes a detour unit that detours the laser light traveling through the part of the branching optical paths. The image display device according to claim 1.

6. The branching optical path selection system selects the part of the branching optical paths as the branching optical path through which the laser light travels from the optical path branching unit when the laser light is modulated according to a first pixel region of the image information in frame units, and selects another part of the branching optical paths among the plurality of branching optical paths as the branching optical path through which the laser light travels from the optical path branching unit when the laser light is modulated according to a second pixel region of the image information in frame units. The image display device according to claim 5.

7. The branching optical path selection system alternately performs, for each at least one frame, selecting the part of the branching optical paths as the branching optical path through which the laser light travels from the optical path branching unit and selecting another part of the branching optical paths among the plurality of branching optical paths. The image display device according to claim 5.

8. Another branching optical path selection system including another optical path branching unit that branches the optical path in which the plurality of branched optical paths are combined by the optical path combining system into a plurality of other branched optical paths; another optical path combining system that combines the plurality of other branched optical paths; and further comprising: the another branching optical path selection system selects at least one of the plurality of other branched optical paths as the other branched optical path through which the laser light travels from the another optical path branching unit based on the image information, and further comprises a second optical processing system that performs optical processing on the laser light traveling through a part of the plurality of other branched optical paths. The image display device according to claim 1.

9. In the light source system, the magnitude of excitation to the laser light source exceeds the oscillation threshold value, and the second optical processing system includes a light attenuation unit that attenuates the laser light traveling through a part of the other branched optical paths. The image display device according to claim 8.

10. The another branching optical path selection system selects a part of the other branched optical paths as the other branched optical path through which the laser light travels from the another optical path branching unit when the luminance of the image information is within a first luminance range equal to or less than a predetermined value, and selects the other branched optical paths of the plurality of other branched optical paths as the other branched optical path through which the laser light travels from the another optical path branching unit when the luminance of the image information is within a second luminance range greater than the predetermined value. The image display device according to claim 9.

11. The second optical processing system includes a detour unit that detours the laser light traveling through a part of the other branched optical paths. The image display device according to claim 8.

12. The another branching optical path selection system selects a part of the other branched optical paths as the other branched optical path through which the laser light travels from the another optical path branching unit when the laser light is modulated according to a first pixel region of the image information in frame units, and selects the other branched optical paths of the plurality of other branched optical paths as the other branched optical path through which the laser light travels from the another optical path branching unit when the laser light is modulated according to a second pixel region of the image information in frame units. The image display device according to claim 11.

13. The image display device according to claim 11, wherein the other branch optical path selection system alternately performs, for each at least one frame, selecting the partial other branch optical path as the other branch optical path along which the laser light travels from the other optical path branching unit, and selecting the other branch optical paths of the other part among the plurality of other branch optical paths.

14. The image display device according to claim 1, wherein the branch optical path selection system includes a polarization state variable element that can vary the polarization state of the laser light from the light source system, and at least the optical path branching unit among the optical path branching unit and the optical path combining system includes a polarization beam splitter.

15. The image display device according to claim 8, wherein the other branch optical path selection system includes a polarization state variable element that can vary the polarization state of the laser light from the optical path combining system, and at least the other optical path branching unit among the other optical path branching unit and the other optical path combining system includes a polarization beam splitter.

16. The image display device according to claim 1, wherein the at least one laser light source is a plurality of laser light sources having mutually different emission wavelengths, and the branch optical path selection system, the optical path combining system, and the first optical processing system are provided for each of the laser light sources.

17. The image display device according to claim 1, wherein the optical path branching unit includes an element in which a plurality of pixels are two-dimensionally arranged.

18. The image display device according to claim 8, wherein the other optical path branching unit includes an element in which a plurality of pixels are two-dimensionally arranged.

19. An image display method including: a step of emitting modulated laser light according to image information; a step of selecting, based on the image information, at least one of the plurality of branch optical paths as the branch optical path along which the laser light whose optical path is branched into the plurality of branch optical paths travels; a step of performing first optical processing on the laser light traveling along the partial branch optical path when the partial branch optical path among the plurality of branch optical paths is selected as the branch optical path along which the laser light travels; and a step of combining the plurality of branch optical paths. Step of selecting at least one of the plurality of other branched optical paths as the other branched optical path through which the laser beam travels, where the combined optical path formed by combining the plurality of branched optical paths is branched into a plurality of other branched optical paths; step of performing a second optical process on the laser beam traveling through the selected partial other branched optical paths when some of the plurality of other branched optical paths are selected as the other branched optical path through which the laser beam travels; and step of combining the plurality of other branched optical paths. The image display method according to claim 19, further comprising these steps.

Images