Optical device, retinal projection display device, and head-mounted display device

Abstract

To combine an expanded viewing zone and high resolution of an image formed on an image forming object.SOLUTION: An optical device includes: a light source; scanning means for scanning light irradiated from the light source; optical deflection means for deflecting the scanned light so as to irradiate onto an image formation object; reflection means disposed between the scanning means and the image formation object; and control means for controlling the scanning means and the optical deflection means. The scanning means can deflect the light in a different direction from a deflection direction of the optical deflection means. The control means can control the deflection direction of the optical deflection means and the deflection direction of the scanning means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical device, a retinal projection display device, and a head mounted display device. [Background technology]

[0002] 2. Description of the Related Art There is known an optical device that has a light source and a scanning means for scanning light emitted from the light source, and irradiates an image formation target with the scanned light.

[0003] Also disclosed is a wearable head-up display including a support structure that is worn on a user's head during use, a laser scanning projector carried by the support structure, a holographic combiner carried by the support structure and positioned within the field of view of one eye of the user when the support structure is worn on the user's head, and an exit pupil selector carried by the support structure and positioned in an optical path between the laser scanning projector and the holographic combiner (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, the configuration of Patent Document 1 leaves room for improvement in terms of expanding the viewing area of ​​the image formed on the image formation target and in terms of resolution.

[0005] An object of the present invention is to achieve both an enlarged viewing area and high resolution for an image formed on an image formation target. [Means for solving the problem]

[0006] An optical device according to one aspect of the present invention includes a light source, a scanning means for scanning light irradiated from the light source, a light deflection means for deflecting the scanned light so as to irradiate an image formation target, a reflecting means disposed between the scanning means and the image formation target, and a control means for controlling the scanning means and the light deflection means, wherein the scanning means is capable of deflecting the light in a direction different from a deflection direction of the light deflection means, and the control means is capable of controlling the deflection direction of the light deflection means and the deflection direction of the scanning means. the reflecting means has a plurality of projectable areas divided in a first direction and a second direction perpendicular to the first direction, the scanning means scans light within the range of one of the divided projectable areas, and the control means moves the projectable area scanned by the scanning means to an adjacent projectable area in the first direction by controlling a deflection direction of the light deflection means, and moves the projectable area scanned by the scanning means to an adjacent projectable area in the second direction by controlling the deflection direction of the scanning means. . Effect of the Invention

[0007] According to the present invention, it is possible to achieve both an enlarged viewing area and high resolution for an image formed on an image formation target. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the overall configuration of a retinal projection display device according to a first embodiment. [Diagram 2] 3 is a diagram illustrating an example of the configuration of a scanning mirror according to the first embodiment. FIG. [Diagram 3] 3 is a diagram illustrating an example of the configuration of a deflection mirror according to the first embodiment. FIG. [Figure 4] 3 is a block diagram of an example of a hardware configuration of a control unit according to the first embodiment. FIG. [Diagram 5] 4 is a block diagram of an example of a functional configuration of a control unit according to the first embodiment. FIG. [Figure 6] 6A and 6B are diagrams showing an example of the configuration of a projection optical element according to a first embodiment, in which FIG. 6A is a plan view and FIG. 6B is a perspective view. [Figure 7] 7A and 7B are diagrams illustrating a first example of the operation of the scanning mirror according to the first embodiment, where FIG. 7A is a diagram of a driving waveform, and FIG. 7B is a diagram of a scanning light. [Figure 8] 8A and 8B are diagrams illustrating a second example of the operation of the scanning mirror according to the first embodiment, where FIG. 8A is a diagram of a driving waveform, and FIG. 8B is a diagram of a scanning light. [Figure 9]9A and 9B are diagrams for explaining a third example of the operation of the scanning mirror according to the first embodiment, where FIG. 9A is a diagram of a driving waveform, and FIG. 9B is a diagram of a scanning light. [Figure 10] 10A and 10B are diagrams showing an example of the operation of the deflection mirror in the first embodiment, in which FIG. 10(a) is a diagram showing the case where projection is made to the center, FIG. 10(b) is a diagram showing the case where projection is made to the left end side, and FIG. 10(c) is a diagram showing the case where projection is made to the right end side. [Figure 11] 11A to 11C are diagrams illustrating an example of a viewing zone switching operation in the Y direction according to the first embodiment. [Figure 12] 11A to 11C are diagrams illustrating an example of a viewing zone switching operation in the X direction according to the first embodiment. [Figure 13] 1A to 1C are diagrams illustrating the effects of the retinal projection display device according to the first embodiment. [Figure 14] 14A and 14B are diagrams showing examples of driving voltages for a deflection mirror according to the second embodiment, in which FIG. 14A is a diagram showing a case where the embodiment is not applied, and FIG. 14B is a diagram showing a case where the embodiment is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and duplicated explanations will be omitted as appropriate.

[0010] Furthermore, the embodiments shown below are illustrative of an optical device for embodying the technical ideas of the present invention, and the present invention is not limited to the embodiments shown below. Unless otherwise specified, the shapes of the components described below, their relative positions, parameter values, etc. are intended to be illustrative and not to limit the scope of the present invention. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0011] The optical device according to the embodiment has a light source and a scanning means for scanning the light emitted from the light source, and irradiates the scanned light onto an image formation target. An example of such an optical device is a retinal projection display device. A retinal projection display device is a device that displays an image by projecting an image onto the retina through the eyeball of a user who wears the retinal projection display device in front of the eye or on the head. This image includes a still image, a video, or a video.

[0012] However, the optical device is not limited to a retinal projection display device, and may be a display device such as a projector or a head-up display, or may be an optical device other than a display device.

[0013] An imaging target refers to an object on which an optical device forms an image. For example, in a retinal projection display device, the imaging target corresponds to the human retina. A retinal projection display device can display an image by forming an image on the retina.

[0014] In such optical devices, the range in which a user can view an image formed by the scanned light may be limited. For example, in a retinal projection display device, the range in which a user can view an image is limited by the viewing zone. Here, the viewing zone refers to the spatial region around the eyeball in which a user wearing a retinal projection display device can move their line of sight without losing sight of the image. The viewing zone is also sometimes called the eye box.

[0015] When a user can only see a narrow range of an image, the viewing zone is said to be narrow, and when a user can see a wide range of an image, the viewing zone is said to be wide. When the viewing zone is narrow, even a slight change in the line of sight can cause the image to deviate from the viewing zone, and the user cannot see part of the image.

[0016] The optical device according to the embodiment includes a light deflection means for deflecting the scanned light so as to irradiate an image formation target, and a reflection means disposed between the scanning means and the image formation target. The optical device also includes a control means for controlling the scanning means and the light deflection means. The scanning means is capable of deflecting light in a direction different from the deflection direction of the light deflection means, and the control means is capable of controlling the deflection direction of the light deflection means and the deflection direction of the scanning means.

[0017] Here, scanning refers to continuously changing the direction of light irradiation at a fixed time interval. For example, an image is formed on an image formation target by scanning light. Deflection refers to discretely changing the direction of light irradiation at an indefinite time interval. For example, a light deflection means changes the position of the image formed on the image formation target by deflecting the image formed by the scanned light.

[0018] In an embodiment, the control means makes it possible to control the deflection direction of the optical deflection means and the deflection direction of the optical scanning means, and by changing the position of the image formed by the scanned light, it is possible to achieve both an expanded viewing area and high resolution for the image formed on the image formation target.

[0019] Hereinafter, the embodiment will be described in detail, taking a retinal projection display device as an example of an optical device.

[0020] In the figures below, directions may be indicated by the X-axis, Y-axis, and Z-axis, but the X-direction along the X-axis indicates the horizontal direction when the retinal projection display device is worn by a user. The Y-direction along the Y-axis indicates the vertical direction when the retinal projection display device is worn by a user. The Z-direction along the Z-axis indicates the direction perpendicular to both the X-axis and the Y-axis.

[0021] Additionally, the direction in which the arrow points in the X direction is denoted as the +X direction and the opposite direction of the +X direction is denoted as the -X direction, the direction in which the arrow points in the Y direction is denoted as the +Y direction and the opposite direction of the +Y direction is denoted as the -Y direction, the direction in which the arrow points in the Z direction is denoted as the +Z direction and the opposite direction of the +Z direction is denoted as the -Z direction. However, these do not limit the orientation of the retinal projection display device, and the orientation of the retinal projection display device is arbitrary.

[0022] [First embodiment] (Example of the overall configuration of the retinal projection display device 100) The overall configuration of a retinal projection display device 100 according to the first embodiment will be described with reference to Fig. 1. The retinal projection display device according to the embodiment is a wearable terminal, and is a retinal drawing type head mounted display (HMD) that uses Maxwellian vision to form (draw) an image directly on the user's retina by laser scanning.

[0023] In the embodiment, a retinal projection display device for the right eyeball of a user will be described as an example, but the same applies to the left eyeball. It is also possible to provide two retinal projection display devices and apply them to both eyeballs. In addition, the terms laser beam and laser beam in the embodiment are synonymous.

[0024] Fig. 1 is a diagram showing an example of the configuration of a retinal projection display device 100. As shown in Fig. 1, the retinal projection display device 100 includes an image laser light source unit 1, a lens 2, a lens 3, a scanning mirror 4, a deflection mirror 5, a projection optical element 6, a detection laser light source 7, a photodetection element 8, and a reflection element 9. The retinal projection display device 100 also includes a glasses frame 10 and a control unit 11.

[0025] The eyeglass frame 10 includes temples 101 and rims 102, and an eyeglass lens 103 is held by the rims 102. The image laser light source unit 1, lens 2, lens 3, scanning mirror 4, deflection mirror 5, and control unit 11 are provided inside the temple 101. The projection optical element 6 is provided on the surface of the eyeglass lens 103 held by the rims 102. A user can wear the retinal projection display device 100 on his / her head by putting the eyeglass frame 10 on his / her ears.

[0026] The image laser light source unit 1 emits image laser beams L of a single or multiple wavelengths. i The image laser light source unit 1 is an example of a light source. When a monochrome image is to be displayed, the image laser light source unit 1 emits a single-wavelength image laser beam L i In the case of displaying a color image, a laser light source that emits laser beams of a plurality of wavelengths, such as a red semiconductor laser, a green semiconductor laser, and a blue semiconductor laser, is used as the image laser light source unit 1. The image laser light source unit 1 is driven by a formation drive signal S L1 In response to the image laser beam L i is fired.

[0027] Image laser beam L emitted from the image laser light source unit 1 i The light intensity of the laser beam is limited to an appropriate light intensity that takes into full consideration the safety of the user's eyes. If necessary, the imaging laser light source unit 1 may be configured to include an optical element that reduces the light intensity of the laser beam.

[0028] In addition, at least one photodiode is disposed in the imaging laser light source unit 1, and the imaging laser beam L emitted is adjusted so as not to exceed an appropriate light intensity that takes into full consideration the safety of the user's eyes. i The light intensity of the light source 1 may be monitored.

[0029] The appropriate light intensity considering the safety of the user's eyes refers to a light intensity below Class 1 defined in IEC (International Electro-technical Commission) 60825-1, which is an international standard regarding the safety of laser light. Furthermore, the imaging laser light source unit 1 is not limited to a semiconductor laser, and a solid-state laser or a gas laser may be used.

[0030] The scanning mirror 4 is a mirror that swings (rotates) around two axes that are substantially perpendicular to each other, and is used to detect the image laser beam L irradiated from the image laser light source unit 1. i The scanning mirror 4 is an example of a scanning unit that scans the image laser beam L incident thereon by swinging and changing the angle. i The retina 32 is scanned to form an image displayed in one field of view on the retina 32 of the eyeball 30. The retina 32 is an example of an image forming target.

[0031] In this embodiment, the scanning mirror 4 is configured to receive the image laser beam L i The laser beam L is scanned in the X and Y directions. The X direction in FIG. 1 corresponds to the main scanning direction in which pixels are drawn successively in time to form a series of pixel groups. The Y direction corresponds to the sub-scanning direction, which is perpendicular to the main scanning direction and lines up a series of pixel groups. The scanning speed in the main scanning direction is set to be faster than the scanning speed in the sub-scanning direction. The scanned image laser beam L i An image is formed by

[0032] The scanning mirror 4 is driven by a scanning drive signal S S By controlling the above, the deflection direction of the image light can be discretely switched in n steps along the Y direction, and the position on the retina 32 of the image formed on the retina 32 can be switched. n is an integer of 1 or more. In this embodiment, an example is shown in which the deflection direction of the image light is switched in n=3 steps, but this is not limiting, and the value of n can be selected appropriately. Note that the image light means light for forming an image.

[0033] A two-axis MEMS (Micro Electro Mechanical System) mirror can be used as the scanning mirror 4. The configuration of the scanning mirror 4 will be described in detail with reference to FIG. 2, and the operation of the scanning mirror 4 will be described in detail with reference to FIGS.

[0034] The deflection mirror 5 is provided between the scanning mirror 4 and the projection optical element 6. The deflection mirror 5 is configured to deflect the image laser beam L by changing the inclination. i The deflection mirror 5 deflects the scanned image laser beam L i The deflection mirror 5 is an example of an optical deflection means that deflects the light so as to irradiate the retina 32. The deflection direction of the deflection mirror 5 can be switched discretely and selectively. The deflection mirror 5 swings around an axis along the Y direction, and is driven by a deflection drive signal S T The tilt angle is fixed at one of the m levels.

[0035] The deflected image light is irradiated towards the projection optical element 6. The deflection mirror 5 can switch the deflection direction of the image light by the scanning mirror 4 in m steps along the X direction, where m is an integer equal to or greater than 1. In this embodiment, an example is shown in which the deflection direction of the image light is switched in m=3 steps, but the present invention is not limited to this, and the value of m can be selected appropriately.

[0036] For example, a uniaxial MEMS mirror can be used as the deflection mirror 5. The configuration of the deflection mirror 5 will be described in detail with reference to FIG. 3, and the operation of the deflection mirror 5 will be described in detail with reference to FIG.

[0037] The projection optical element 6 is an example of a reflecting means disposed between the scanning mirror 4 and the retina 32. The projection optical element 6 reflects the image laser beam L irradiated from the deflection mirror 5. i The holographic optical element reflects and focuses the light toward the user's eyeball 30. The holographic optical element is an example of a reflecting light focusing element and an example of a hologram. The holographic optical element is composed of at least one holographic film.

[0038] The projection optical element 6 is an element in which n×m=x [number] of hologram regions having different light-collecting characteristics are optically recorded. Note that x is an integer of 2 or more. For example, when n=1, m=2 can be set, and when m=1, n=2 can be set. In this embodiment, a configuration in which x=9 is illustrated, but this is not limiting, and the value of x can be appropriately selected.

[0039] Each hologram area is formed by irradiating an image laser beam L i The x=9 [points] visual field is a field of view in which the image laser beam L i is positioned so as to be contained within the pupil 31 of the user's eye.

[0040] The material of the holographic film may be Bayfol (registered trademark) HX available from Bayer MaterialScience AG, or a photopolymer film. The configuration and operation of the projection optical element 6 will be described in detail later with reference to FIG.

[0041] The configuration including the detection laser light source 7 and the light detection element 8 is an example of a gaze direction detection unit that detects the gaze direction of a user wearing the retinal projection display device 100. The detection laser light source 7 projects a detection laser beam L S The photodetector element 8 detects the irradiated detection laser beam L S The reflected light from the eyeball 30 is received, and a detection signal S corresponding to the intensity of the received light is generated. D is output to the control unit 11.

[0042] The control unit 11 receives the detection signal S D The control unit 11 estimates the user's line of sight based on the line of sight, and acquires information indicating the line of sight. The control unit 11 also controls the position at which the image is projected onto the retina 32 in accordance with the acquired line of sight information.

[0043] Detection signal S Dis an example of projection position information or image formation target position information for providing the projection position to the control unit 11, and the light detection element 8 is an example of a projection position output means for outputting the projection position information or image formation target position information to the control unit 11. However, the configuration of the gaze direction detection unit is not limited to a configuration including the detection laser light source 7 and the light detection element 8, and any eye tracking technology may be applied.

[0044] The detection laser light source 7 is configured to direct a detection laser beam L S The detection laser light source 7 is an array light source such as a VCSEL (Vertical Cavity Surface Emitting Laser) or an LDA (Laser Diode Array) that irradiates a laser beam L. The detection laser light source 7 has nine light emitting parts corresponding to the number of visual fields provided by the x=9 visual zones. S The wavelength of the light is preferably a wavelength of near-infrared light, which is invisible light, so as not to impede the visibility of the user whose line of sight is to be detected. However, the wavelength is not limited to this and may be visible light.

[0045] The light detection element 8 detects the detection laser beam L emitted from the x [units] light emitting units of the detection laser light source 7, incident on the eyeball 30 via the reflecting element 9, and reflected by the eyeball 30. S At least one photodiode for receiving the light.

[0046] The corneal surface, which corresponds to the surface of the eyeball 30, is a transparent body containing water and generally has a reflectance of about 2 to 4%. S The detection laser beam L emitted from each of the x light-emitting elements included in the detection laser light source 7 is reflected by an area P on the corneal surface of the eyeball 30 and enters the light detection element 8. S The light is received by the photodetector element 8 only when the user is viewing each field of view that is paired with each light emitting portion.

[0047] The light detection element 8 is not limited to a photodiode, and may be an image pickup element such as a CCD or CMOS. The detection laser beam L S may be detected.

[0048] The control unit 11 receives image data Dat that is the source of the image to be formed, and generates an image laser beam L from the image laser light source unit 1 based on the image data Dat. i In addition, the detection drive signal S L2 The detection laser beam L s In addition, the emission timing of each light emitting part of the detection laser light source 7 and the detection signal S by the light detection element 8 are controlled. D Based on this, the line of sight direction is estimated, that is, which of the predetermined x=9 fields of view the line of sight is directed to. Also, the scanning drive signal S S Thus, the image laser beam L i The scanning of the deflection mirror 5 is controlled by the deflection drive signal S T The inclination of the deflection mirror 5 is controlled by this.

[0049] In addition, in FIG. 1, the imaging laser light source unit 1 is provided inside the temple 101, but the present invention is not limited to this. The imaging laser light source unit 1 is provided outside the temple 101, and the imaging laser beam L emitted from the imaging laser light source unit 1 is i may be configured to guide the light into the inside of temple 101. Furthermore, control unit 11 may be provided inside temple 101, or control unit 11 may be provided outside temple 101, and each drive signal from control unit 11 may be supplied to the inside of temple 101.

[0050] In addition, while FIG. 1 shows an example of a configuration in which the projection optical element 6 is provided on the surface of the eyeglass lens 103, the present invention is not limited to this, and the projection optical element 6 may be integrated with the eyeglass lens 103.

[0051] Furthermore, the scanning mirror 4 is not limited to a biaxial MEMS mirror, and may be configured to use two uniaxial MEMS mirrors. Furthermore, optical elements capable of scanning light, such as polygon mirrors and galvanometer mirrors, may be used, or a combination of these may be used. However, using a MEMS mirror is preferable because it allows the retinal projection display device 100 to be made smaller and lighter. In particular, a configuration using only a biaxial MEMS mirror is even more preferable because it allows the retinal projection display device 100 to be made smaller and lighter. The driving method of the MEMS mirror may be any of electrostatic, piezoelectric, electromagnetic, etc.

[0052] Moreover, the deflection mirror 5 is not limited to a MEMS mirror, and may be a combination of an actuator and a mirror, or an optical element such as a digital mirror device (DMD; Digital Micro-mirror Device). However, using a MEMS mirror is preferable because it allows the retinal projection display device 100 to be made smaller and lighter.

[0053] Next, still referring to FIG. 1, the image laser beam L i This section explains the behavior of .

[0054] In FIG. 1, an image laser beam L , which is a divergent light emitted from an image laser light source unit 1, i is converted into a substantially parallel light by lens 2, and is shaped into a desired laser beam state by lens 3. Note that, although the example of Fig. 1 shows a configuration including lenses 2 and 3, lens 3 is not necessarily required as long as the laser beam can be shaped into a desired laser beam state.

[0055] Laser beam L for imaging shaped into a desired beam state i is scanned in two axial directions by the scanning mirror 4, is reflected by the deflection mirror 5, and enters the projection optical element 6. Note that, although FIG. 1 illustrates an example in which the deflection mirror 5 is disposed between the scanning mirror 4 and the projection optical element 6, the present invention is not limited to this. iThe light may be scanned in two axial directions by a scanning mirror 4 and made to enter a projection optical element 6 .

[0056] The projection optical element 6 projects the image laser beam L i is reflected toward the user's eyeball 30 and enters the inside of the eyeball 30. The light incident on the inside of the eyeball 30 is once focused near the center of the pupil 31 by the focusing function of the hologram area of ​​the projection optical element 6, and then projected onto the retina 32 located at the back of the eyeball 30, where an approximate image is formed.

[0057] The above-mentioned visual state is generally called Maxwellian vision, and the image laser beam L passing through the vicinity of the center of the pupil 31 is i It is generally understood that because the light reaches the retina 32 regardless of the focusing ability of the crystalline lens, a user can see the image formed on the retina 32 clearly and in focus no matter where in real space the user focuses his or her eye.

[0058] On the other hand, in reality, the laser beam incident on the eyeball 30 has a finite diameter, even though it is small, so the lens effect of the crystalline lens is not insignificant. Therefore, in this embodiment, the focusing effect of the projection optical element 6 reduces the image laser beam L i The diameter of the light source is between 350 and 500 μm, and the beam divergence angle is a positive finite value, i.e., the light is divergent.

[0059] As a result, the image laser beam L scanned by the scanning mirror 4 i The image formed by the laser beam L1 reaches the retina 32 through the projection optical element 6 without being affected by the focusing of the crystalline lens, so that the user can always clearly view the formed image no matter where in the real space the user focuses the eye. i The image formed by the above is viewed by the user in a focus-free state.

[0060] In addition, the retinal projection display device 100 changes the current or voltage applied to the imaging laser light source unit 1 to emit imaging laser beam L i This allows the brightness of the image to be adjusted according to the brightness of the surrounding environment in which the retinal projection display device 100 is used.

[0061] (Example of the configuration of scanning mirror 4) Next, the configuration of the scan mirror 4 will be described with reference to Fig. 2. Fig. 2 is a diagram illustrating an example of the configuration of the scan mirror 4. As shown in Fig. 2, the scan mirror 4 includes a support substrate 91, a movable portion 92, a serpentine beam portion 93, a serpentine beam portion 94, and an electrode connection portion 95.

[0062] The scanning mirror 4 is driven by a scanning drive signal S applied through an electrode connection 95. S In response to this, the serpentine beams 93 and 94 are driven to swing the movable part 92 supported by the serpentine beams 93 and 94 around the A1 axis. In addition, the scanning mirror 4 drives the torsion bar 92b included in the movable part 92 to swing the reflection mirror 92a supported by the torsion bar 92b around the B1 axis.

[0063] The scanning mirror 4 reflects the image laser beam L i The movable part 92 is swung about the A1 axis to scan in the direction along the α1 axis, and the reflecting mirror 92a is swung about the B1 axis to scan in the direction along the β1 axis, thereby scanning in two axial directions that are approximately perpendicular to each other.

[0064] The serpentine beam portion 93 is formed in a serpentine shape with multiple folded portions, one end of which is connected to the support substrate 91 and the other end of which is connected to the movable portion 92. The serpentine beam portion 93 includes a beam portion 93a including three beams and a beam portion 93b including three beams. The beams of the beam portion 93a and the beams of the beam portion 93b are formed alternately. Each of the beams included in the beam portion 93a and the beam portion 93b is independently provided with a piezoelectric member.

[0065] Similarly, the serpentine beam portion 94 is formed in a serpentine manner with a plurality of folded portions, one end of which is connected to the support substrate 91, and the other end of which is connected to the movable portion 92. The serpentine beam portion 94 includes a beam portion 94a including three beams and a beam portion 94b including three beams. The beams of the beam portion 94a and the beams of the beam portion 94b are formed alternately. Each of the beams included in the beam portion 94a and the beam portion 94b is independently provided with a piezoelectric member. The number of beams in the beam portions 93a and 93b is not limited to three and may be any number.

[0066] The piezoelectric members of the beams 93a, 93b, 94a, and 94b are formed as piezoelectric layers in parts of the layers of each beam formed in a multi-layer structure, for example. Hereinafter, the piezoelectric members of the beams 93a and 94a are collectively referred to as piezoelectric member 96a, and the piezoelectric members of the beams 93b and 94b are collectively referred to as piezoelectric member 96b.

[0067] When voltage signals of opposite phases are applied to the piezoelectric members 96a and 96b to warp each of the meandering beams 93 and 94, the adjacent beams bend in different directions. These bendings accumulate, generating a driving force for reciprocatingly swinging the reflecting mirror 92a around the axis A1 in FIG.

[0068] The movable portion 92 is formed so as to be sandwiched in the β1 axis direction between a serpentine beam portion 93 and a serpentine beam portion 94. The movable portion 92 includes a reflecting mirror 92a, a torsion bar 92b, a piezoelectric member 92c, and a support portion 92d.

[0069] The reflection mirror 92a is formed, for example, by evaporating a metal thin film containing aluminum, gold, silver, etc. onto a base material. The torsion bar 92b has one end connected to the reflection mirror 92a and extends in the positive and negative α1 axis directions to support the reflection mirror 92a so that it can swing.

[0070] One end of the piezoelectric member 92c is connected to the torsion bar 92b, and the other end is connected to the support portion 92d. When a voltage is applied to the piezoelectric member 92c, the piezoelectric member 92c is bent and deformed, causing a twist in the torsion bar 92b. The twist in the torsion bar 92b becomes a driving force, and the reflection mirror 92a swings around the B1 axis.

[0071] The reflection mirror 92a swings about the A1 axis in accordance with the swing of the movable portion 92, so that the image laser beam L i The image laser beam L incident on the reflecting mirror 92a is scanned in the α1 axis direction by the oscillation of the reflecting mirror 92a around the B1 axis. i is scanned in the β1 axis direction.

[0072] The support portion 92d is formed to surround the reflection mirror 92a, the torsion bar 92b, and the piezoelectric member 92c. The support portion 92d is connected to the piezoelectric member 92c and supports the piezoelectric member 92c. The support portion 92d also indirectly supports the torsion bar 92b and the reflection mirror 92a, which are connected to the piezoelectric member 92c.

[0073] The support substrate 91 is formed to surround the movable portion 92, the serpentine beam portion 93, and the serpentine beam portion 94. The support substrate 91 is connected to and supports each of the serpentine beam portion 93 and the serpentine beam portion 94. The support substrate 91 also indirectly supports the movable portion 92 connected to the serpentine beam portion 93 and the serpentine beam portion 94.

[0074] The scanning mirror 4 is formed by micromachining silicon or glass, for example, using micromachining technology. Micromachining technology allows highly accurate and minute reflecting mirrors to be formed on a substrate together with driving parts such as serpentine beams.

[0075] Specifically, for example, one SOI (Silicon On Insulator) substrate is shaped by etching or the like. A reflective mirror, a serpentine beam, a piezoelectric member, an electrode connection section, and the like are integrally formed on the shaped substrate, and the scanning mirror 4 is formed as a MEMS mirror. The reflective mirror and the like may be formed after or during the shaping of the SOI substrate.

[0076] An SOI substrate is a substrate in which a silicon oxide layer is provided on a silicon support layer made of single crystal silicon (Si), and a silicon active layer made of single crystal silicon is further provided on the silicon oxide layer. The silicon active layer is thinner in the γ1-axis direction, which is approximately perpendicular to both the α1-axis and the β1-axis, than in the α1-axis and the β1-axis directions, so that a member made only of the silicon active layer functions as an elastic part having elasticity.

[0077] The SOI substrate does not necessarily have to be flat, and may have a curvature, etc. Furthermore, the material used to form the MEMS mirror is not limited to the SOI substrate, so long as it can be integrally formed by etching or the like and can be made partially elastic.

[0078] (Example of the configuration of the deflection mirror 5) Next, the configuration of the deflection mirror 5 will be described with reference to Fig. 3. Fig. 3 is a diagram illustrating an example of the configuration of the deflection mirror 5. As shown in Fig. 3, the deflection mirror 5 includes a support substrate 41, a movable portion 42, a serpentine beam portion 43, and a serpentine beam portion 44.

[0079] The deflection mirror 5 is driven by a deflection drive signal S applied through an electrode connection portion. T The deflection mirror 5 drives the meandering beams 43 and 44 in response to the deflection mirror 5, thereby tilting the movable part 42 supported by the meandering beams 43 and 44 around the A2 axis. i is deflected in the direction along the α2 axis by the inclination of the movable portion 42 about the A2 axis.

[0080] The serpentine beam portion 43 is formed in a serpentine shape with a plurality of folded portions, one end of which is connected to the support substrate 41, and the other end of which is connected to the movable portion 42. The serpentine beam portion 43 includes a beam portion 43a including three beams and a beam portion 43b including three beams. The beams of the beam portion 43a and the beam portion 43b are alternately formed. Each of the beams included in the beam portion 43a and the beam portion 43b is independently provided with a piezoelectric member.

[0081] Similarly, the serpentine beam portion 44 is formed in a serpentine shape with multiple folded back portions, one end of which is connected to the support substrate 41 and the other end of which is connected to the movable portion 42. The serpentine beam portion 44 includes a beam portion 44a including three beams and a beam portion 44b including three beams. The beams of the beam portion 44a and the beam portion 44b are formed alternately. Each of the beams included in the beam portion 44a and the beam portion 44b is independently provided with a piezoelectric member.

[0082] The number of beams in the beam portions 43a and 43b is not limited to three and may be any number. The piezoelectric members included in the beam portions 43a, 43b, 44a, and 44b are formed as piezoelectric layers in parts of the layers of each beam formed in a multi-layer structure, for example. Hereinafter, the piezoelectric members included in the beam portions 43a and 44a are collectively referred to as piezoelectric member 45a, and the piezoelectric members included in the beam portions 43b and 44b are collectively referred to as piezoelectric member 45b.

[0083] When voltages of opposite phases are applied to the piezoelectric members 45a and 45b to warp the meandering beam 44, adjacent beams bend in different directions. These bendings accumulate, generating a driving force for tilting the reflecting mirror 42a around the A2 axis.

[0084] The movable portion 42 is formed so as to be sandwiched between the serpentine beam portion 43 and the serpentine beam portion 44 in the β2 axis direction. The movable portion 42 has a reflecting mirror 42a in the center portion, and the reflecting mirror 42a is tilted around the A2 axis by the driving force of the serpentine beam portion 43 and the serpentine beam portion 44. The imaging laser beam L that is incident on and reflected by the reflecting mirror 42a is i is deflected in the α2 axis direction by this tilt.

[0085] The support substrate 41 is formed to surround the movable portion 42, the serpentine beam portion 43, and the serpentine beam portion 44. The support substrate 41 is connected to and supports the serpentine beam portion 43 and the serpentine beam portion 44. The support substrate 41 also indirectly supports the movable portion 42 connected to the serpentine beam portion 43 and the serpentine beam portion 44.

[0086] Like the scanning mirror 4, the deflection mirror 5 can be formed by micromachining silicon or glass, and therefore a duplicated description will be omitted here.

[0087] (Example of hardware configuration of control unit 11) Next, the hardware configuration of the control unit 11 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing an example of the hardware configuration of the control unit 11.

[0088] 4, the control unit 11 includes a CPU (Central Processing Unit) 22, a ROM (Read Only Memory) 23, a RAM (Random Access Memory) 24, an external I / F 25, a light source drive circuit 26, a scanning mirror drive circuit 27, and a deflection mirror drive circuit 28. These are electrically connected to each other via a system bus SB.

[0089] The CPU 22 is a calculation device that reads out programs and data from a storage device such as the ROM 23 onto the RAM 24 and executes processing to realize overall control and functions of the control unit 11. The RAM 24 is a volatile storage device that temporarily stores programs and data.

[0090] The ROM 23 is a non-volatile storage device that can retain programs and data even when the power is turned off, and stores processing programs and data that the CPU 23 executes to control each function of the retinal projection display device 100.

[0091] The external I / F 25 is an interface with an external device, a network, etc. Examples of the external device include a higher-level device such as a PC (Personal Computer), a USB memory, an SD card, a CD, a DVD, a HDD, an SSD, and other storage devices. Examples of the network include a CAN (Controller Area Network) or a LAN (Local Area Network) in an automobile, the Internet, etc. The external I / F 25 may have any configuration that enables connection or communication with an external device, and an external I / F 25 may be provided for each external device.

[0092] The light source drive circuit 26 is an electric circuit that is electrically connected to the imaging laser light source unit 1 and the detection laser light source 7 and drives them by applying a current or voltage. L1 According to the above, the image laser beam L i or the emission of the image laser beam L i The detection laser light source 7 changes the light intensity of the formation drive signal S outputted from the light source drive circuit 26. L1 Depending on the S or the emission of the detection laser beam L S Change the light intensity.

[0093] The scan mirror drive circuit 27 is an electric circuit that is electrically connected to the scan mirror 4 and applies a voltage to the scan mirror 4 to drive it. S is driven according to

[0094] The deflection mirror drive circuit 28 is an electric circuit that is electrically connected to the deflection mirror 5 and applies a voltage to the deflection mirror 5 to drive it. The deflection mirror 5 is driven by a deflection drive signal S T is driven according to

[0095] The control unit 11 can acquire image data Dat from an external device or a network via the external I / F 25. However, the control unit 11 is not limited to acquiring image data Dat from an external device or a network, and may acquire image data Dat stored in advance in the ROM 23 in the control unit 11, or may provide a storage device such as an SD card in the control unit 11 and acquire image data Dat from the storage device.

[0096] The control unit 11 can realize the following functional configuration by instructions from the CPU 22 and the hardware configuration shown in FIG.

[0097] (Example of functional configuration of control unit 11) Next, the functional configuration of the control unit 11 will be described with reference to Fig. 5. Fig. 5 is a block diagram showing an example of the functional configuration of the control unit 11.

[0098] 5, the control unit 11 includes a gaze direction estimation unit 51, an image formation control unit 52, a light source control unit 53, a scanning mirror control unit 54, and a deflection mirror control unit 55. These functions are realized by the CPU 22 in FIG. 4 executing a predetermined program stored in a ROM or the like, and by the light source drive circuit 26, the scanning mirror drive circuit 27, the deflection mirror drive circuit 28, etc.

[0099] The gaze direction estimation unit 51 detects the emission timing of each light emitting unit included in the detection laser light source 7 and the detection signal S output by the light detection element 8. D Based on this, it is estimated which of the predefined x=9 visual fields the gaze is in.

[0100] The image formation control unit 52 acquires image data from an external device, and generates a formation drive signal S based on the image data and information indicating the field of view recognized by the user, which is estimated by the line of sight direction estimation unit 51. L1 , scanning drive signal S S and deflection drive signal S T Then, the image formation control unit 52 generates the formation drive signal S L1The scanning mirror control unit 54 outputs the scanning drive signal S S is supplied to the scanning mirror 4 by the deflection mirror control unit 55 as a deflection drive signal S T are respectively output to the deflection mirror 5.

[0101] In addition, if the image visually recognized by the user has distortion, etc., control may be performed to correct this. In addition, the image formation control unit 52 outputs projection information to the imaging laser light source unit 1 via the light source control unit 53, and is therefore an example of a projection information output means that outputs projection information to the light source.

[0102] (Example of the configuration of the projection optical element 6) Next, the configuration of the projection optical element 6 will be described with reference to Fig. 6. Fig. 6 is a diagram for explaining an example of the configuration of the projection optical element 6. Fig. 6(a) is a plan view, and Fig. 6(b) is a perspective view.

[0103] As shown in Fig. 6(a), the projection optical element 6 has x=9 divided hologram areas H1 to H9. Each of the hologram areas H1 to H9 is an example of a projectable area that reflects and focuses light incident under a predetermined incident condition to a predetermined position. The predetermined incident condition is the position and direction of the incident light that is specified for each of the hologram areas H1 to H9.

[0104] 6(b), hologram regions H1 to H9 reflect light emitted from corresponding emission regions L1 to L9, respectively, and focus the light at different x=9 positions near the corresponding pupil 31. This provides x=9 viewing zones E1 to E9.

[0105] The emission regions L1 to L9 are, for example, nine regions with different positions on the horizontal plane of the scanning mirror 4. The viewing regions E1 to E9 are, for example, nine regions with different positions on the pupil 31 of the eyeball 30. When the emission regions L1 to L9 are not distinguished, they are collectively referred to as the emission region L, and when the viewing regions E1 to E9 are not distinguished, they are collectively referred to as the viewing region E.

[0106] Figure 6(b) illustrates how light emitted from emission region L4, located on the middle left of the emission regions L arranged in a matrix of 3 rows and 3 columns, is reflected by hologram region H4 of the projection optical element 6 and concentrated in the viewing zone E4.

[0107] Moreover, the projection optical element 6 reflects only light with a wavelength in a band that is very narrow compared to the visible light range, and transmits light with other wavelengths. Therefore, most of the light traveling from the real space toward the user's eyeball 30 can transmit through the projection optical element 6 and enter the eyeball 30.

[0108] When reflecting and focusing light of multiple wavelengths, the projection optical element 6 may be configured with one layer of wavelength-multiplexed holographic film, or may be configured by laminating multiple holographic film layers each including in its band the multiple wavelengths to be reflected and focused.

[0109] The projection optical element 6 projects the image laser beam L i It is sufficient if the light can be focused at nine different positions. For example, the hologram regions H1 to H9 may be formed by one-shot exposure on a single layer of holographic film, or nine holographic films corresponding to the hologram regions H1 to H9 may be formed separately and each may be bonded to glass or a transparent film with an adhesive or the like to produce the projection optical element 6.

[0110] It should be noted that the pattern showing the hologram regions H1 to H9 shown in FIG. 6 is an image and differs from the actual pattern.

[0111] (Example of operation of scanning mirror 4) Next, the operation of the scanning mirror 4 will be described with reference to FIGS.

[0112] Fig. 7 is a diagram for explaining an example of the operation when the reference voltages of the drive voltage A applied to the piezoelectric member 95a of the scan mirror 4 and the drive voltage B applied to the piezoelectric member 95b are equal. Fig. 7(a) is a diagram showing the waveform of the drive voltage, and Fig. 7(b) is a diagram showing the operation of the scan mirror 4 when the drive voltage of Fig. 7(a) is applied.

[0113] The scanning mirror 4 reflects the image laser beam L i In the case of scanning in the main scanning direction (X direction), the scanning drive signal S S As a result, a driving voltage having a sine wave waveform is applied to the piezoelectric member 92c. As a result, the scanning mirror 4 causes the movable part 92 to reciprocate around the B axis at the period of the driving voltage. For example, when the frequency of the driving voltage is 20 [kHz], which is approximately equal to the resonance frequency of the torsion bar 92b, the movable part 92 can be made to resonate and oscillate at 20 [kHz] by utilizing mechanical resonance caused by the twisting of the torsion bar 92b.

[0114] The waveform of the driving voltage is not limited to a sine wave, and may be, for example, a sawtooth wave. A sawtooth wave can be generated by superposing sine waves, and a waveform with rounded peaks or a waveform with curved linear regions of a sawtooth wave may be used.

[0115] The scanning mirror 4 reflects the image laser beam L i In the case of scanning in the sub-scanning direction (Y direction), the scanning drive signal S S The waveform of the driving voltage A applied to the piezoelectric member 95a is, for example, a sawtooth waveform, and the frequency of the driving voltage A is, for example, 60 [Hz].

[0116] Here, if the minimum value of the driving voltage A is the reference voltage Va (Va≧0), the duration of the rise period during which the voltage value increases from the minimum value to the next maximum value is Tr, and the duration of the fall period during which the voltage value decreases from the maximum value to the next minimum value is Tf, then the waveform of the driving voltage A is preset to a ratio of, for example, Tr:Tf=9:1.

[0117] The waveform of the driving voltage B applied to the piezoelectric member 95b is a sawtooth waveform, similar to the driving voltage A. The frequency of the driving voltage B is 60 [Hz], for example. Here, the minimum value of the driving voltage B is set as a reference voltage Vb (Vb≧0). The waveform of the driving voltage B is preset to have a ratio of, for example, Tf:Tr=9:1.

[0118] As shown in FIG. 7(a), when the reference voltages of the driving voltage A and the driving voltage B are equal (Va=Vb) and the maximum values ​​are equal, the standard vertical driving state for scanning in the sub-scanning direction is established. i The image forming drive signal S L1 Based on this, the flickering image laser beam L i By synchronizing with the above, an image can be formed as shown in Figure 7(b).

[0119] FIG. 7(b) shows the image laser beam L i 1 shows how the retina is scanned and an image is projected onto a scanned surface 73. Here, the scanned surface 73 is an example of a plurality of projectable areas. A projection area 74 is an area on the scanned surface 73 onto which an image is projected, and a non-projection area 75 is an area on the scanned surface 73 onto which an image is not projected. In the retinal projection display device 100, the scanned surface 73 corresponds to a surface included in the projection optical element 6.

[0120] The control unit 11 can form a projection area 74 and a non-projection area 75 on a scanned surface 73 corresponding to the projectable area by controlling the deflection direction of the scanning mirror 4.

[0121] If the area onto which an image is projected by the driving voltage in the standard vertical driving state is taken as projection area 74 in the standard vertical driving state, then by making a difference between the reference voltages of driving voltage A and driving voltage B (Va>Vb or Vb>Va) while maintaining the waveforms of driving voltage A and driving voltage B, the area onto which the image is projected can be displaced up and down along the Y direction relative to projection area 74.

[0122] In addition, if the reference voltages of drive voltage A and drive voltage B are equal (Va=Vb) and have waveforms with equal maximum values, the drive voltage pattern in the standard vertical drive state is not limited to the pattern shown in Fig. 7(a). For example, even if the offset voltage is Vo (Vo>0), Va=Vb=Vo, and the drive voltage pattern in which the maximum values ​​of drive voltage A and drive voltage B are equal is used, an image can be projected onto the projection area 74 as shown in Fig. 7(b).

[0123] Next, Fig. 8 is a diagram for explaining an example of the operation when the reference voltage of the driving voltage A applied to the piezoelectric member 95a is larger (Va>Vb) than the driving voltage B applied to the piezoelectric member 95b of the scanning mirror 4. Fig. 8(a) is a diagram showing the waveform of the driving voltage, and Fig. 8(b) is a diagram showing the operation of the scanning mirror 4 when the driving voltage of Fig. 8(a) is applied.

[0124] As shown in Fig. 8(a), while maintaining the waveform of the driving voltage in Fig. 7(a) in the standard vertical driving state, an offset voltage Vo is applied to the reference voltage Va of the driving voltage A applied to the piezoelectric member 95a of the scanning mirror 4, so that Va = Vo > Vb. In this case, as shown in Fig. 8(b), an image can be projected onto a projection area 74' displaced in the +Y direction relative to the projection area 74 (see Fig. 7(b)) in the standard vertical driving state. A non-projection area 75' is an area on the scanned surface 73 on which an image is not projected in this case.

[0125] 9A and 9B are diagrams for explaining an example of the operation when the reference voltage of the driving voltage B applied to the piezoelectric member 95b of the scanning mirror 4 is larger (Vb>Va) than the driving voltage A applied to the piezoelectric member 95a of the scanning mirror 4. Fig. 9A is a diagram showing the waveform of the driving voltage, and Fig. 9B is a diagram showing the operation of the scanning mirror 4 at the driving voltage of Fig. 9A.

[0126] As shown in Fig. 9(a), while maintaining the waveform of the driving voltage in Fig. 7(a) in the standard vertical driving state, an offset voltage Vo is applied to the reference voltage Vb of the driving voltage B applied to the piezoelectric member 95b of the scanning mirror 4, so that Vb = Vo > Va. In this case, as shown in Fig. 9(b), an image can be projected onto a projection area 74" displaced in the -Y direction with respect to the projection area 74 (see Fig. 7(b)) in the standard vertical driving state. A non-projection area 75" is an area on the scanned surface 73 on which an image is not projected in this case.

[0127] 7 to 9, the position of the image projection area can be changed in three steps along the Y direction simply by controlling the driving voltages that change the combination of the driving voltages A and B applied to the scanning mirror 4. In other words, the scanning mirror 4 projects the image laser beam L i By deflecting the light, the position of the image projection area can be changed in three steps along the Y direction.

[0128] (Example of the operation of the deflection mirror 5) Next, the operation of the deflection mirror 5 will be described with reference to Fig. 10. Fig. 10 is a diagram for explaining an example of the operation of the deflection mirror 5. Fig. 10(a) is a diagram showing the waveform of the driving voltage and the operation of the deflection mirror 5 when the driving voltage C is equal to the driving voltage D, and Fig. 10(b) is a diagram showing the waveform of the driving voltage and the operation of the deflection mirror 5 when the driving voltage C is larger than the driving voltage D. Fig. 10(c) is a diagram showing the waveform of the driving voltage and the operation of the deflection mirror 5 when the driving voltage D is larger than the driving voltage C.

[0129] The control unit 11 outputs a deflection drive signal S T A driving voltage C is applied as a direct current (DC) voltage to the piezoelectric member 43A (44A), and a driving voltage D, which is also a DC voltage and has a phase opposite to that of the driving voltage C, is applied to the piezoelectric member 43B (44B).

[0130] As shown in FIG. 10A, when the applied drive voltages C and D are equal, the movable part 42 of the deflection mirror 5 remains stationary while maintaining an inclination at an angle of θ (θ≧0) with respect to the X-axis. Here, the drive state in which the applied drive voltages C and D are equal is defined as the standard horizontal drive state, and the image laser beam L incident in the standard horizontal drive state is i The region on the scanned surface 83 where the light is reflected and an image is projected is defined as a projection region 84. A non-projection region 85 is a region on the scanned surface 83 where the image is not projected.

[0131] Here, the scanned surface 83 is an example of a plurality of projectable areas. The control unit 11 can form a projection area 84 and a non-projection area 85 on the scanned surface 83 corresponding to the projectable area by controlling the deflection mirror 5.

[0132] 10(b), when the driving voltage C is greater than the driving voltage D, the movable part 42 of the deflection mirror 5 remains stationary while maintaining an inclination at an angle θL (θL>θ) with respect to the X-axis. i The reflection direction of the light beam can be changed in the -X direction with respect to the projection area 84. The projection area 84' indicates an area on the scanned surface 83 onto which an image is projected, and the non-projection area 85' is an area on the scanned surface 83 onto which an image is not projected.

[0133] 10(c), when the driving voltage D is greater than the driving voltage C, the movable part 42 of the deflection mirror 5 remains stationary while maintaining the inclination at an angle of θR (θR<θ) with respect to the X-axis. i The reflection direction of the light beam can be changed in the +X direction with respect to the projection area 84. The projection area 84" indicates an area on the scanned surface 83 onto which an image is projected, and the non-projection area 85" is an area on the scanned surface 83 onto which an image is not projected.

[0134] In this way, by changing the magnitude relationship between the drive voltages C and D, the inclination of the movable portion 42 of the deflection mirror 5 can be changed in three stages, similar to the scanning mirror 4. This makes it possible to change the position of the image projection area in three stages along the X direction simply by controlling the drive voltage applied to the deflection mirror 5. In other words, the deflection mirror 5 deflects the scanned image laser beam L i By deflecting the light, the position of the image projection area can be changed in three steps along the X direction.

[0135] (Example of viewing zone switching operation by the retinal projection display device 100) ((Switching in Y direction)) Next, the viewing zone switching operation in the Y direction by the retinal projection display device 100 will be described with reference to Fig. 11. Fig. 11 is a diagram for explaining an example of the viewing zone switching operation in the Y direction by the retinal projection display device 100.

[0136] In FIG. 11, the image laser beam L i is scanned by the scanning mirror 4 to form image light Im. The deflection direction of the image light Im changes along the Y direction due to the drive voltage of the scanning mirror 4, and the image light Im is irradiated onto the deflection mirror 5 as image light Im1 to Im3, deflected by the deflection mirror 5, and projected onto the projection optical element 6. Note that the image light Im is a general term for the image light Im1 to Im3.

[0137] Image light Im2 is image light formed by the scanning mirror 4 in the standard vertical drive state shown in Fig. 7. Image light Im1 is image light formed by the scanning mirror 4 when a drive voltage that satisfies Va>Vb shown in Fig. 8 is applied. Image light Im3 is image light formed by the scanning mirror 4 when a drive voltage that satisfies Vb>Va shown in Fig. 9 is applied.

[0138] 11, when the deflection mirror 5 is in the standard horizontal drive state, the image light Im reflected by the deflection mirror 5 is projected onto three areas aligned in the Y direction at the center of the projection optical element 6. Specifically, the image light Im1 is projected onto the hologram area H2, the image light Im2 is projected onto the hologram area H5, and the image light Im3 is projected onto the hologram area H8.

[0139] The hologram regions H1 to H9 included in the projection optical element 6 reflect and collect the image light Im projected onto each region at a predetermined position. The image light Im is configured to satisfy the incidence conditions for each of the hologram regions H1 to H9. Specifically, the image light Im1 satisfies the incidence conditions for the hologram region H2, the image light Im2 satisfies the incidence conditions for the hologram region H5, and the image light Im3 satisfies the incidence conditions for the hologram region H8.

[0140] As a result, the image light Im1 is reflected by the hologram area H2 and collected in the viewing zone E2, the image light Im2 is reflected by the hologram area H5 and collected in the viewing zone E5, and the image light Im3 is reflected by the hologram area H8 and collected in the viewing zone E8.

[0141] The retinal projection display device 100 is configured so that when the user is wearing the device and looks straight ahead, the viewing zone E5 is included in the user's pupil 31. The user can view an image within a finite viewing angle provided by the viewing zone E5.

[0142] The viewing zone E2 is located above the user, and the viewing zone E8 is located below the user. The retinal projection display device 100 is configured so that when the user moves his / her line of sight upward beyond the finite viewing angle of the viewing zone E5, the user is provided with a visual field by the viewing zone E2, and when the user moves his / her line of sight downward beyond the finite viewing angle of the viewing zone E5, the user is provided with a visual field by the viewing zone E8.

[0143] As a result, even if the user moves his / her line of sight upward or downward beyond the finite viewing angle provided by the viewing zone E5, the user can view the image, and the viewing zone can be expanded. The retinal projection display device 100 can change the viewing zone in three stages along the Y direction by controlling the drive voltage of the scanning mirror 4, and can expand the viewing zone along the Y direction.

[0144] ((Switching in X direction)) Next, the viewing zone switching operation in the X direction by the retinal projection display device 100 will be described with reference to Fig. 12. Fig. 12 is a diagram for explaining an example of the viewing zone switching operation in the X direction by the retinal projection display device 100.

[0145] In FIG. 12, the image laser beam L i is scanned by the scanning mirror 4 in the standard vertical drive state to form image light Im. The image light Im is deflected in three different directions in the X direction according to the inclination of the deflection mirror 5, and projected onto three areas aligned in the X direction at the center of the projection optical element 6.

[0146] The image light Im2 is image light deflected at an angle θ when the deflection mirror 5 is driven in the standard horizontal drive state as shown in Fig. 10(a). The image light Im4 is image light deflected at an angle θL when a drive voltage is applied such that drive voltage C>drive voltage D as shown in Fig. 10(b). The image light Im5 is image light deflected at an angle θR when a drive voltage is applied such that drive voltage D>drive voltage C as shown in Fig. 10(c).

[0147] Image light Im4 is projected onto hologram region H4, image light Im2 onto hologram region H5, and image light Im5 onto hologram region H6, depending on the tilt of deflection mirror 5. Image light Im4 satisfies the incidence condition for hologram region H4, image light Im2 satisfies the incidence condition for hologram region H5, and image light Im5 satisfies the incidence condition for hologram region H6.

[0148] As a result, image light Im4 is reflected by hologram region H4 and collected in viewing zone E4, image light Im2 is reflected by hologram region H5 and collected in viewing zone E5, and image light Im5 is reflected by hologram region H6 and collected in viewing zone E6.

[0149] The viewing zone E4 is located to the left as viewed by the user, and the viewing zone E6 is located to the right as viewed by the user. The retinal projection display device 100 is configured so that when the user moves his / her line of sight to the left beyond the finite viewing angle of the viewing zone E5, the user is provided with a field of view by the viewing zone E4, and when the user moves his / her line of sight to the right beyond the finite viewing angle of the viewing zone E5, the user is provided with a field of view by the viewing zone E6.

[0150] As a result, even if the user moves his / her line of sight to the left or right beyond the finite viewing angle provided by the viewing zone E5, the user can view the image, and the viewing zone can be expanded. The retinal projection display device 100 can change the viewing zone in three stages along the X direction by controlling the drive voltage of the deflection mirror 5, thereby expanding the viewing zone along the X direction.

[0151] In this way, in the retinal projection display device 100, by controlling the driving voltage of the scanning mirror 4, the deflection direction of the image light Im projected onto the projection optical element 6 can be changed in three stages in the Y direction, and by controlling the driving voltage of the deflection mirror 5, the deflection direction of the image light Im projected onto the projection optical element 6 can be changed in three stages in the X direction.

[0152] In other words, by combining the drive voltage controls of the scanning mirror 4 and the deflection mirror 5, the deflection direction of the image light Im formed by the scanning mirror 4 can be changed in x=3×3=9 directions.

[0153] By ensuring that the image light Im projected onto each of the hologram regions H1 to H9 satisfies the incidence conditions of each region, the image light Im can be concentrated into x=9 [number] of viewing zones E1 to E9 arranged on the 3 x 3 array shown in Figure 6.

[0154] The user can view the image light Im no matter where he or she looks in the field of view provided by the viewing zones E1 to E9, and can selectively view the field of view provided by any one of the viewing zones E1 to E9 by changing the line of sight. In addition, since the hologram regions H1 to H9 are provided separately in the projection optical element 6, it is possible to optimize the light collection characteristics of each hologram region on the viewing zones E1 to E9 so that they are substantially equal. This makes it possible to provide uniform image quality in the field of view provided by any of the viewing zones E1 to E9.

[0155] The finite viewing angles of the visual fields provided by each of the visual fields E1 to E9 in the retinal projection display device 100 may be the same for all x=9 [areas] or may be different for each visual field. The finite viewing angles are, for example, 13[deg]×6.5[deg], 16[deg]×9[deg], 20[deg]×12[deg], etc., as the horizontal viewing angle×vertical viewing angle.

[0156] (Functions and Effects of the Retinal Projection Display Device 100) Next, the effects of the retinal projection display device 100 will be described.

[0157] In recent years, technologies and products related to virtual reality (VR) and augmented reality (AR) have been attracting attention. In particular, AR technology is expected to be applied to the consumer and industrial fields as a means of presenting digital information that adds value as an extension of the visualization of the real world, and glass-type image display devices that can be used in active and working environments are being developed as products for implementation.

[0158] In order to simultaneously view the real world and an image (digital image), the mainstream type is a transmissive (see-through) type, and image display device terminals that display a virtual image in front of the eye via an eyepiece optical system such as a partially reflective film or an image guide structure have been introduced onto the market.

[0159] However, in image display terminals that display virtual images, the focus must be on an image drawn at a fixed depth, limiting the depth plane on which objects in real space and the image can be focused simultaneously, which impedes natural human behavior (tasks).

[0160] In response to this, a method using a laser to directly draw an image on the retina has been attracting attention in recent years. The method uses Maxwellian vision to focus an image on the pupil and then project it onto the retina.

[0161] Light that passes through the center of the pupil reaches the retina without being affected by the focusing ability of the crystalline lens, resulting in a focus-free feature that is suitable for any wearer's eyesight, making it possible to clearly see images regardless of where in the outside world the focus is set.

[0162] On the other hand, the retinal imaging method has the disadvantage that the viewing zone (eye box) is relatively narrow because the image is focused on the pupil once. The viewing zone (eye box) is the spatial area around the eye where the user can move their gaze without losing sight of the image, and when the viewing zone is narrow, even a slight change in the gaze can cause the image to disappear.

[0163] In response to this issue, a viewing zone expansion technology (Patent Document 1) has been proposed in recent years that is capable of focusing image light at multiple positions by providing an exit pupil selector and multiple holograms in the optical system. The technology in Patent Document 1 is a candidate technology for providing a wearable head-mounted display with an expanded viewing zone, as it is capable of duplicating the viewing zone with the above configuration, or switching the viewing zone in response to eyeball movement when combined with eye tracking.

[0164] However, the viewing zone expansion technology described in Patent Document 1 constantly aligns the user's pupil with the focusing position of the image light, which means that all of the image light enters the pupil, and the entire display content is always visible within the field of view.

[0165] Therefore, in image display based on laser scanning, the resolution decreases as the viewing angle of the image to be shown to the user increases. Also, since the exit pupil selector is configured to undergo changes in position such as translation and rotation, it is difficult to reduce the size of the exit pupil selector, which in turn hinders the overall miniaturization of the wearable head-up display and impairs the design of the device worn by a person.

[0166] Furthermore, when switching viewing zones to display images that follow eye movements, delays become an issue due to the nature of the display involving changes in position, such as translation and rotation.As such, there are still many challenges to overcome in order to achieve both improved visibility as a display device and an aesthetically pleasing design as glasses.

[0167] In contrast, the retinal projection display device 100 (optical device) according to this embodiment includes an image laser light source unit 1 (light source) and an image laser beam L irradiated from the image laser light source unit 1. i A scanning mirror 4 (scanning means) for scanning (light) and a scanned image laser beam L i and a deflection mirror 5 (light deflection means) that deflects the light so as to irradiate a retina 32 (image formation target).

[0168] The retinal projection display device 100 also includes a projection optical element 6 (reflection means) disposed between the scanning mirror 4 and the retina 32. It further includes a control unit 11 (control means) that controls the scanning mirror 4 and the deflection mirror 5.

[0169] The scanning mirror 4 directs the image laser beam L in a direction different from the deflection direction of the deflection mirror 5. i The control unit 11 can control the deflection direction of the deflection mirror 5 and the deflection direction of the scanning mirror 4.

[0170] The control unit 11 controls the deflection direction of the deflection mirror 5 and the deflection direction of the scanning mirror 4, and the scanned image laser beam L i By changing the position of the image formed by the above, it is possible to achieve both an enlarged viewing area and high resolution of the image formed on the retina 32.

[0171] FIG. 13 is a diagram for explaining the effects of the retinal projection display device 100. As shown in FIG.

[0172] 13, an image laser beam Li is scanned by a scanning mirror 4 to become image light Im, which is deflected by a deflection mirror 5 and then enters a projection optical element 6. Thereafter, the image light Im is reflected by the projection optical element 6 and once focused near the center of a pupil 31 of a user's eyeball 30, and then projected onto a retina 32 of the user.

[0173] The user can visually recognize the image light Im projected onto the retina 32. The light propagating in the -Z direction from the object 70 in real space has a wide wavelength band including the visible light range. The projection optical element 6 has excellent transparency because the hologram functions only for a very narrow band of wavelengths compared to the visible light range.

[0174] Therefore, most of the light propagating from the real space toward the user's eyeball 30 passes through the projection optical element 6 and reaches the retina 32. As a result, the image of the object 70 in the real space is visually recognized with sufficient brightness.

[0175] In this way, a user wearing the retinal projection display device 100 can view the image and the image of the object 70 in real space in parallel, and can view both the image and the image in real space in a bright state. In addition, in this embodiment, an image is formed directly on the user's retina 32 by using Maxwellian vision, so that the user can view the images in parallel and clearly regardless of where the focus is set in real space.

[0176] On the other hand, the retinal imaging method using Maxwellian vision has the disadvantage that the viewing zone is relatively narrow due to the characteristic that the image light Im is focused once on the pupil 31. In a situation where the viewing zone is narrow, a phenomenon that the image disappears due to a slight change in the line of sight may occur.

[0177] In this embodiment, by controlling the driving voltage of the scanning mirror 4, the deflection direction of the image light Im to the projection optical element 6 can be changed in three stages along the Y direction, and by controlling the driving voltage of the deflection mirror 5, the deflection direction of the image light Im to the projection optical element 6 can be changed in three stages along the X direction.

[0178] By combining the drive voltage control of the scanning mirror 4 and the deflection mirror 5, the deflection direction of the image light Im to the projection optical element 6 can be changed in nine directions. The user can secure nine fields of view corresponding to the nine viewing zones arranged in a 3 x 3 array. In other words, the user can view the image no matter where he or she looks in the nine fields of view. This makes it possible to expand the viewing zone in which the image can be viewed, even though it is a retinal drawing method.

[0179] In addition, this embodiment includes a gaze direction estimation unit 51, which can estimate which of the nine visual fields the user is looking at. By controlling the driving voltages of the scanning mirror 4 and the deflection mirror 5 so that the image is displayed in the estimated visual field, the user can view the image no matter which area of ​​the nine visual fields he or she looks at.

[0180] The user can see the image in one of the nine fields of view that the user is looking at. This makes it possible to always display an image in the direction of the user's gaze as long as it is within the nine fields of view, making it possible to project an image that follows the user's gaze.

[0181] The images projected into each of the nine visual fields may be the same or different. For example, if the image is always the same regardless of the switching of the visual field, it will be possible to always display the same image by following the line of sight within the range of the nine visual fields.

[0182] This will be useful for supporting workplaces in manufacturing and other industries where it is important to always have information displayed in front of one's line of sight, as well as for general consumers to check information about objects they are looking at in their daily lives.

[0183] In addition, if different images are displayed in each field of view, the necessary information or data to be displayed in front of the line of sight can be predetermined, and the necessary information can be confirmed by directing one's gaze to the set field of view when necessary.

[0184] In other words, it is possible to have a video experience that is left to the user's will to watch when they want to watch. This cannot be achieved by the viewing zone duplication method that is often seen in conventional disclosed technologies. As a result, for example, if the user is a manufacturing worker or infrastructure inspection worker, the clear field of vision does not hinder work in the real world, and digital content such as work instructions can be clearly viewed only when the line of sight is moved at the necessary timing, and the focus-free system allows the user to work without visual stress, which is expected to improve work efficiency more than ever before.

[0185] In this embodiment, the viewing angle of the image formed by the scanning mirror 4 remains within one viewing range, and the viewing range is switched to the one the user is looking at among the nine viewing ranges by controlling the driving voltage of the scanning mirror 4 and the deflection mirror 5. In other words, the resolution does not change depending on the viewing range, and the resolution for scanning within one viewing range is maintained in every viewing range.

[0186] Generally, in image display based on laser scanning, the larger the viewing angle of the image to be shown to the user, the lower the resolution. However, in the retinal projection display device 100, the area in which the display can be viewed, the viewing zone, is expanded, and the field of view onto which the image can be projected without degrading the resolution is expanded.

[0187] In addition, in this embodiment, the viewing zone can be switched simply by controlling the drive voltages of the scanning mirror 4 and the deflection mirror 5, which are micro-sized MEMS mirrors, and therefore no mechanism or device requiring physical operation is required. This simplifies the optical system and enables the retinal projection display device to be significantly miniaturized.

[0188] [Second embodiment] Next, a retinal projection display device 100a according to a second embodiment will be described. When drive voltages C and D including a DC voltage are applied in parallel to the deflection mirror 5 as differential signals (opposite phase signals), the deflection mirror 5 vibrates according to the natural frequency of the deflection mirror 5, and the image displayed on the retinal projection display device 100 may fluctuate until the vibration subsides. In this embodiment, such vibration of the deflection mirror 5 is reduced by controlling the drive voltage.

[0189] Fig. 14 is a diagram illustrating an example of vibration reduction of the deflection mirror 5. Fig. 14(a) is a diagram illustrating a waveform of a driving voltage when the embodiment is not applied and a deflection angle of the movable part 42 in the deflection mirror 5. Fig. 14(b) is a diagram illustrating a waveform of a driving voltage when the embodiment is applied and a deflection angle of the movable part 42 in the deflection mirror 5.

[0190] 14(a), when the tilt of the movable part 42 changes from θR to angle θL by applying the driving voltages C' and D' according to the comparative example, a damped oscillation 111 occurs, and after the lapse of time t, the damped oscillation 111 converges and the deflection angle of the movable part 42 stabilizes. During this time t, the image displayed on the retinal projection display device 100 wobbles.

[0191] 14(b), in this embodiment, a predetermined time difference Δt is provided between the timing at which the voltage value of the drive voltage C serving as the first drive voltage changes and the timing at which the voltage value of the drive voltage D serving as the second drive voltage changes. This allows the vibrations accompanying the change in drive voltage C and the vibrations accompanying the change in drive voltage D to cancel each other out, thereby reducing the damped vibration of the movable part 42. For example, the vibrations can be most suitably reduced by providing a time difference Δt that is approximately half the natural period of the deflection mirror 5.

[0192] In the example of Fig. 14(b), the driving voltage D changes after the driving voltage C changes, but the present invention is not limited to this, and the driving voltage C may change after the driving voltage D changes. In addition, in Fig. 14(b), a time difference Δt is added to the rising timing of the driving voltage, but the same effect can be obtained by adding a time difference Δt to the falling timing.

[0193] There are no particular limitations on the waveforms of the drive voltages C and D. In addition to the ramp-like shape shown in FIG. 14(b), the same effect can be obtained by adding a time difference Δt to waveforms that switch instantaneously or change exponentially.

[0194] Other effects and advantages than those mentioned above are similar to those described in the first embodiment.

[0195] Although the retinal projection display device according to the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications and improvements are possible within the scope of the present invention.

[0196] In the above-described embodiment, a retinal projection display device has been described as an example of an optical device, but the optical device may be a head-mounted display device that is not only attached directly to a person's head, but also indirectly attached to a person's head via a member such as a fixing part.

[0197] In addition, all the numbers such as ordinal numbers and quantities used above are merely examples for specifically explaining the technology of the present invention, and the present invention is not limited to the exemplified numbers. In addition, the connection relationships between the components are merely examples for specifically explaining the technology of the present invention, and the connection relationships for realizing the functions of the present invention are not limited to these.

[0198] Each function of the above-described embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, and a device such as an ASIC (Application Specific Integrated Circuit), a DSP (digital signal processor), an FPGA (field programmable gate array), or a conventional circuit module designed to execute each function described above. [Explanation of symbols]

[0199] 1. Laser light source for images (example of light source) 2, 3 Lenses 4. Scanning mirror (an example of a scanning means) 5 Deflection mirror (an example of a deflection means) 6 Projection optical element (an example of a reflecting means) 7 Detection laser light source 8 Photodetector (an example of a projection position output means) 9 Reflective elements 10. Eyeglass frames 101 Crane 102 Rim 103 Eyeglass Lenses 11 Control unit (an example of a control means) 30 Eyeball 31 Pupil 32 Retina (an example of an image-forming object) 51 Gaze direction estimation unit 52 Image formation control section 53 Light source control unit 54 Scanning mirror control section 55 Deflection mirror control unit 73, 83 Scanned surface (an example of multiple projectable areas) 74, 84 Projection area 75, 85 Non-projection area A, B drive voltage SL1 formation drive signal SL2 detection drive signal Dat Image data L i Imaging laser beam L S Detection laser beam S S Scanning Drive Signal S T Deflection Drive Signal S D Detection signal (an example of projection position information or image formation target position information) H1 to H9: Hologram area (an example of a reflective light-collecting element) L1 to L9 output area E1 to E9 viewing area

Prior Art Documents

Patent Documents

[0200]

Patent Document 1

Claims

1. A light source; A scanning means for scanning the light irradiated from the light source; a light deflection means for deflecting the scanned light so as to irradiate an image forming target; a reflecting means disposed between said scanning means and said imaging object; a control unit for controlling the scanning unit and the optical deflection unit, the scanning means is capable of deflecting the light in a direction different from a deflection direction of the light deflection means, the control means is capable of controlling a deflection direction of the optical deflection means and a deflection direction of the scanning means, the reflecting means has a plurality of projectable areas divided in a first direction and a second direction perpendicular to the first direction, the scanning means scans light within a range of one of the divided projectable areas, The control means controls the deflection direction of the optical deflection means to move the projectable area scanned by the scanning means to the adjacent projectable area in the first direction, and controls the deflection direction of the scanning means to move the projectable area scanned by the scanning means to the adjacent projectable area in the second direction.

2. 2. The optical device according to claim 1, wherein the reflecting means includes a reflecting and focusing element for reflecting and focusing light in each of the divided projectable areas.

3. 3. The optical device of claim 2, wherein the reflective light-collecting element is a hologram.

4. 4. The optical device according to claim 1, wherein different images are formed on the image formation target by the light scanned by the scanning means.

5. a projection position output means for outputting projection position information or image formation target position information to the control means, 5. The optical device according to claim 1, wherein the control means controls the light deflection means and the deflection direction of the scanning means based on the projection position information or the image formation target position information.

6. 6. The optical device according to claim 1, further comprising projection information output means for outputting projection information to said light source.

7. the image forming target is at least one of a retina or a pupil of an eye; A tilt detection unit that detects the tilt of the eyeball, 7. The optical device according to claim 1, wherein at least one of the light deflection means and the scanning means deflects the light scanned by the scanning means in accordance with a tilt of the eyeball.

8. 8. The optical device according to claim 1, wherein the control means controls a deflection direction of at least one of the optical deflection means and the scanning means by adjusting a drive voltage.

9. a first driving voltage and a second driving voltage are applied to the optical deflection means as a differential signal; 9. The optical device according to claim 1, wherein a predetermined time difference is provided between a timing at which the voltage value of the first driving voltage changes and a timing at which the voltage value of the second driving voltage changes.

10. A retinal projection display device comprising an optical device according to any one of the preceding claims.

11. A head-mounted display device comprising the optical device according to any one of claims 1 to 9.

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