Retina projection type image display device

Abstract

We provide a retinal projection image display device with a large eyebox. [Solution] The retinal projection image display device is a retinal projection image display device that projects an image onto the retina of an observer, and comprises a light source, a light deflection unit that deflects light emitted from the light source, a light scanning unit that scans the light deflected by the light deflection unit to form the image, and an array optical element arranged in the optical path between the light scanning unit and the observer's retina, which guides the light scanned by the light scanning unit to the observer's retina, wherein the array optical element includes a plurality of individual optical elements arranged in a first direction and a second direction intersecting the first direction, each having refractive power, and the individual optical axes of each of the plurality of individual optical elements are parallel to each other and intersect in the first direction and the second direction, respectively.

Description

Technical Field

[0001] The present invention relates to a retinal projection type image display device.

Background Art

[0002] For example, in Patent Document 1, there is disclosed an image projection device including a light source, a scanning unit that scans image light rays emitted from the light source, and a projection mirror that is disposed in front of a user's eye and converges a plurality of image light rays scanned by the scanning unit and emitted in different directions to a convergence point in the user's eye and then projects them onto the retina.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to provide a retinal projection type image display device having a large eyebox.

Means for Solving the Problems

[0004] A retinal projection type image display device according to an aspect of the present invention is a retinal projection type image display device that projects an image onto a retina of an observer, including a light source, an optical deflector that deflects light emitted from the light source, an optical scanner that scans the light deflected by the optical deflector to form the image, and an array optical element disposed in an optical path between the optical scanner and the retina of the observer and guiding the light scanned by the optical scanner to the retina of the observer. The array optical element includes a plurality of individual optical elements arranged side by side in a first direction and a second direction intersecting the first direction, each having a refractive power, and individual optical axes of each of the plurality of individual optical elements are parallel to each other and intersect each of the first direction and the second direction.

Effects of the Invention

[0005] According to the present invention, it is possible to provide a retinal projection type image display device having a large eyebox.

Brief Description of the Drawings

[0006] [Figure 1] This is a schematic perspective view showing a support on which a retinal projection type image display device according to the first embodiment is arranged. [Figure 2] This is a schematic top view showing the overall configuration of a retinal projection type image display device according to the first embodiment. [Figure 3] This is a schematic top view showing a retinal projection type image display device related to a comparative example. [Figure 4] This is a schematic plan view showing a first example of an array optical element in a retinal projection type image display device according to the first embodiment. [Figure 5] Figure 4 is a schematic cross-sectional view of the VV line. [Figure 6] This is a schematic cross-sectional view showing a second example of an array optical element in a retinal projection type image display device according to the first embodiment. [Figure 7] This figure shows the relationship between the incident angle and the exit angle of the light beam in the individual optical elements of a retinal projection type image display device according to a comparative example. [Figure 8] This figure shows the relationship between the incident angle and the exit angle of the light beam in the individual optical elements of the retinal projection type image display device according to the first embodiment. [Figure 9] This figure shows the relationship between the incident and exit angles of the light beam in individual optical elements where the overall optical axis and the individual optical axis overlap, and the relationship between the incident and exit angles of the light beam in individual optical elements where the overall optical axis and the individual optical axis do not overlap. [Figure 10] This is a schematic top view showing the light deflection section of a retinal projection type image display device according to the first embodiment. [Figure 11] This is a schematic top view showing the optical scanning unit of a retinal projection type image display device according to the first embodiment. [Figure 12] This is a block diagram showing the hardware configuration of the control unit of the retinal projection type image display device according to the first embodiment. [Figure 13] This is a block diagram showing the functional configuration of the control unit of the retinal projection type image display device according to the first embodiment. [Figure 14]This is a schematic top view showing a first example of the placement position of the retinal projection type image display device on the support according to the first embodiment. [Figure 15] This is a schematic top view showing a second example of the placement position of the retinal projection type image display device on the support according to the first embodiment. [Figure 16] This is a schematic top view showing a retinal projection type image display device according to the second embodiment. [Figure 17] This is a block diagram showing the functional configuration of the control unit of the retinal projection type image display device according to the second embodiment. [Figure 18] This is a schematic diagram showing a retinal projection type image display device according to Example 1. [Figure 19] This is a schematic diagram showing a retinal projection type image display device according to Example 2. [Figure 20] This is a schematic diagram showing a retinal projection type image display device according to Example 3. [Figure 21] This is a schematic diagram showing a retinal projection type image display device according to Example 4. [Figure 22] This is a schematic diagram showing a retinal projection type image display device according to Example 5. [Modes for carrying out the invention]

[0007] A retinal projection type image display device according to an embodiment of the present invention will be described in detail with reference to the drawings. However, the following embodiments are illustrative of a retinal projection type image display device according to an embodiment of the present invention and are not limited to those described below.

[0008] The dimensions, materials, shapes, and relative arrangements of the components described in the embodiments of the present invention are merely illustrative examples and not intended to limit the scope of the embodiments of the present invention to those specific forms unless otherwise stated. The size and positional relationships of the members shown in each drawing may be exaggerated for clarity. Furthermore, in the following description, the same name and reference numerals indicate the same or identical members, and detailed explanations are omitted as appropriate. In some cases, end view diagrams showing only the cross-section may be used as cross-sectional views.

[0009] In the following, for the sake of easier explanation, the arrangement and configuration of each part may be described using either the XYZ orthogonal coordinate system or the αβγ orthogonal coordinate system. The three axes in each of the XYZ orthogonal coordinate system and the αβγ orthogonal coordinate system are orthogonal to each other.

[0010] In the XYZ orthogonal coordinate system, the direction in which the X-axis extends is defined as the "X direction", the direction in which the Y-axis extends is defined as the "Y direction", and the direction in which the Z-axis extends is defined as the "Z direction". In the αβγ orthogonal coordinate system, the direction in which the α-axis extends is defined as the "α direction", the direction in which the β-axis extends is defined as the "β direction", and the direction in which the γ-axis extends is defined as the "γ direction". However, the above direction expressions only describe the relationships such as relative positions, orientations, directions, etc., and do not have to match the relationships in use. Also, these directions are independent of the direction of gravity.

[0011] In the drawings shown below, as an example, the line-of-sight direction of an observer observing an image while wearing the retinal projection type image display device according to an embodiment of the present invention corresponds to the -Z direction. Note that the line-of-sight direction refers to the direction of the line of sight when the above observer is looking straight ahead. Also, in the array optical element of the retinal projection type image display device according to an embodiment of the present invention, the direction in which the individual optical axes of each of the plurality of individual optical elements extend corresponds to the X direction. The first direction in which the plurality of individual optical elements are arranged corresponds to the Y direction. The second direction intersecting the first direction corresponds to the Z direction. In this specification, there may be cases where they are denoted as the first direction Y and the second direction Z.

[0012] In the terms of this specification and the claims, the "image" includes not only still images but also moving images. Moving images can also be referred to as videos. In the terms of this specification, "parallel" may include an inclination of ±10 degrees or less with respect to parallel. Also, "orthogonal" may include an inclination of ±10 degrees or less with respect to orthogonal.

[0013] [First Embodiment] <Configuration of the Retinal Projection Type Image Display Device According to the First Embodiment> (Overall Configuration) The retinal projection image display device according to the first embodiment will be described with reference to Figures 1 to 3. Figure 1 is a schematic perspective view showing a support 100 on which the retinal projection image display device 50 according to the first embodiment is arranged. Figure 2 is a schematic top view showing the overall configuration of the retinal projection image display device 50. Figure 3 is a schematic top view showing a retinal projection image display device 50X according to a comparative example. In Figure 3, for the convenience of explanation, components of the retinal projection image display device 50X that have the same function as components of the retinal projection image display device 50 are denoted by the same reference numerals as components of the retinal projection image display device 50.

[0014] In recent years, technologies and products related to virtual reality (VR) and augmented reality (AR) have attracted attention. In particular, AR technology is expected to have applications in consumer and industrial fields as a means of realizing new added value by extending the vision of the real world and integrating digital information into real space. To promote its widespread adoption, image display devices such as head-mounted displays that can be used in action and work environments are being developed. To view the real world and images simultaneously, see-through designs are the mainstream, and head-mounted displays that display virtual images in front of the eyes via eyepiece optical systems such as partial reflective films and image guide structures are being introduced to the market.

[0015] For head-mounted displays used in the real world, optical quality that blends seamlessly into everyday life is a crucial element, but style and design are equally important. Head-mounted displays currently on the market are significantly larger and less fashionable than traditional eyeglass frames, undoubtedly deterring consumers. Pursuing stylishness is a major challenge in this industry. Head-mounted displays need to possess a style that conveys aesthetic appeal while simultaneously delivering new added value—digital images—with sufficient visual quality to the user.

[0016] In light of the above situation, retinal projection image display devices, which project images directly onto the retina, are attracting attention. In commonly used image display terminals that display virtual images, the depth plane in which both real-world objects and the image can be simultaneously focused is limited because the user must focus on an image drawn at a fixed depth, which hinders natural human behavior (work). On the other hand, the retinal projection method utilizes Maxwell's vision to focus the image onto the retina by first focusing it into the pupil, thus achieving focus-free characteristics that do not depend on the observer's visual acuity or depth of focus position. Due to its focus-free characteristics, it is possible to clearly view the image regardless of where the focus is placed in the external world.

[0017] The retinal projection image display device 50 is a display device using the retinal projection method described above. In the example shown in Figures 1 and 2, the retinal projection image display device 50 is placed on a support 100 and displays an image projected onto the observer's retina through the observer's eyeball E wearing the support 100. The observer can observe the image displayed by the retinal projection image display device 50 using Maxwell's vision. From another perspective, the retinal projection image display device 50 is a head-mounted display (HMD) that is attached to the observer's head via the support 100.

[0018] In the example shown in Figure 1, the support 100 includes two vines 151, two light-transmitting members 152, and two frames 153 that support the two light-transmitting members 152, corresponding to the two light-transmitting members 152.

[0019] In the example shown in Figure 1, the retinal projection image display device 50 is positioned on the outer surface of the right-eye side of the two temples 151. However, the retinal projection image display device 50 may be positioned on the outer surface of the left-eye side of the temple 151, on the outer surfaces of both the right-eye and left-eye side temples 151, or on the surface of the frame 153. The retinal projection image display device 50 is not limited to being positioned on the surface of the temple 151 or the frame 153, but may also be positioned inside the temple 151 or the frame 153. Some of the components of the retinal projection image display device 50 may be positioned inside or on the surface of the light-transmitting member 152.

[0020] In the example shown in Figure 1, the retinal projection image display device 50 projects an image onto the observer's retina through the observer's right eyeball E. However, the retinal projection image display device 50 may project an image onto the observer's retina through the observer's left eyeball E, or it may project an image onto the observer's retina through both the right and left eyeballs E.

[0021] The retinal projection image display device 50 may include a support 100 as part of its configuration. In the example shown in Figure 1, the support 100 is a spectacle-type support. However, the support 100 may take various forms such as a headgear type, a hat type, or a helmet type.

[0022] As shown in Figure 2, the retinal projection image display device 50 according to this embodiment includes a light source 1, an optical deflection unit 2 that deflects light L emitted from the light source 1, and an optical scanning unit 3 that scans the light L deflected by the optical deflection unit 2 to form an image. The retinal projection image display device 50 also includes an array optical element 4 positioned between the optical scanning unit 3 and the observer's retina in the optical path of the light L, which guides the light L scanned by the optical scanning unit to the observer's retina. The retinal projection image display device 50 projects the observer's eyeball E onto the observer's retina.

[0023] Furthermore, in the example shown in Figure 2, the retinal projection image display device 50 includes a first optical system 5 arranged in the optical path between the light source 1 and the light deflection unit 2 and having positive refractive power, and a second optical system 6 arranged in the optical path between the light deflection unit 2 and the light scanning unit 3 and having positive refractive power. In addition, the retinal projection image display device 50 includes a third optical system 7 arranged in the optical path between the light scanning unit 3 and the array optical element 4 and having positive refractive power, and a fourth optical system 8 arranged in the optical path between the array optical element 4 and the observer's retina and having positive refractive power. Moreover, the retinal projection image display device 50 includes a polarizing beam splitter 10 arranged in the optical path between the fourth optical system 8 and the observer's retina.

[0024] Refractive power refers to the degree to which an optical system bends incident light. Positive refractive power refers to the degree to which incident light is bent in a way that causes it to focus. On the other hand, negative refractive power refers to the degree to which incident light is bent in a way that causes it to diverge. It should be noted that refractive power is not limited to the degree to which incident light is bent by refraction, but also includes the degree to which it is bent by optical phenomena other than refraction, such as reflection or diffraction. For example, positive refractive power includes the degree to which incident light is bent in a way that causes it to focus by being reflected by a concave mirror.

[0025] In the example shown in Figure 2, the first optical system 5 includes one or two optical elements, each having refractive power. The second optical system 6 includes one or two optical elements, each having refractive power. The third optical system 7 includes one to three optical elements, each having refractive power. The fourth optical system 8 includes one or two optical elements, each having refractive power. An optical element is one or more lenses or mirrors, etc. In the example shown in Figure 2, the optical elements in the first optical system 5, the second optical system 6, and the third optical system 7 are each one lens, and the optical element in the fourth optical system 8 is a concave mirror.

[0026] In the example shown in Figure 2, light L emitted from the light source 1 is imaged at the position of the light deflection unit 2 by the first optical system 5. The "position of the light deflection unit 2" is, for example, on the surface of the deflection plane of the light deflection unit 2. The light L imaged at the position of the light deflection unit 2 is reflected by the deflection plane of the light deflection unit 2, passes through the second optical system 6, and enters the optical scanning unit 3. The light L that enters the optical scanning unit 3 is reflected by the deflection plane of the optical scanning unit 3, passes through the third optical system 7, and enters the array optical element 4. The light L that enters the array optical element 4 passes through the array optical element 4 and enters the polarizing beam splitter 10. A portion of the light L that enters the polarizing beam splitter 10 is reflected by the polarizing beam splitter 10 and enters the fourth optical system 8. The light L that enters the fourth optical system 8 is reflected by the fourth optical system 8, passes through the polarizing beam splitter 10, and is projected onto the retina through the eyeball E. The tilt center of the deflection planes of the optical deflection unit 2 and the optical scanning unit 3, respectively, is located at the center of the deflection plane. The deflection plane of the optical deflection unit 2 will be described later with reference to Figure 10. The deflection plane of the optical scanning unit 3 will be described later with reference to Figure 11.

[0027] For example, in the retinal projection image display device 50X according to the comparative example shown in Figure 3, the light L emitted from the light source 1 is reflected by the deflection plane of the optical scanning unit 3 and then incident on the deflection plane of the optical deflection unit 2. In other words, in the retinal projection image display device 50X, the positions of the optical deflection unit 2 and the optical scanning unit 3 are reversed compared to the retinal projection image display device 50 according to this embodiment.

[0028] In the configuration of the retinal projection image display device 50X, the light L corresponding to each field of view of the image formed by the optical scanning unit 3 is incident at different positions within the deflection surface of the optical deflection unit 2. As a result, the light L corresponding to each field of view is reflected at different defocus positions relative to the deflection surface of the optical deflection unit 2, depending on the inclination of the deflection surface of the optical deflection unit 2. At the central field of view, the light L is focused on the deflection surface of the optical deflection unit 2 even if the deflection surface is inclined. On the other hand, at fields of view other than the central field of view, the light L is not focused on the deflection surface of the optical deflection unit 2, but is reflected by the deflection surface in an unfocused state. Therefore, aberrations occur due to the inclination of the deflection surface of the optical deflection unit 2, i.e., aberrations due to changes in the position of the light beam. As a result, it is difficult to reduce the aberrations that occur because the light L constituting the image is incident on the pupil of the eyeball E.

[0029] In this embodiment, light L emitted from the light source 1 enters the light deflection unit 2 and then enters the light scanning unit 3. The light L corresponding to each field of view of the image formed by the light scanning unit 3 is imaged at the same position at the light deflection unit 2. As a result, even if the deflection surface of the light deflection unit 2 is tilted, aberrations are almost eliminated. Consequently, in this embodiment, aberrations that occur when the light constituting the image enters the pupil of the eyeball E can be reduced.

[0030] (Array optical element 4) The array optical element 4 will be described with reference to Figures 4 to 6. Figure 4 is a schematic plan view showing a first example of the array optical element 4. Figure 5 is a schematic cross-sectional view of the VV line in Figure 4. Figure 6 is a schematic cross-sectional view showing a second example of the array optical element 4.

[0031] As shown in Figures 4 and 5, in this embodiment, the array optical element 4 includes a plurality of individual optical elements 40 arranged in a line in a first direction Y and a second direction Z, each having refractive power. The individual optical axes 40C of each of the plurality of individual optical elements 40 are parallel to each other and intersect in the first direction Y and the second direction Z, respectively. The individual optical axes 40C are axes that pass through the center of the individual optical elements 40 and extend in the direction normal to the array optical element 4, for example, in the X direction.

[0032] In Figure 4, the maximum length D represents the maximum length in the arrangement region 41 where multiple individual optical elements 40 are arranged in the array optical element 4. In the example shown in Figure 4, the arrangement region 41 is a roughly rectangular area in a plan view from the normal direction of the array optical element 4. The maximum length D corresponds to the length of the diagonal in this roughly rectangular area.

[0033] In the array optical element 4 according to the first example shown in Figures 4 and 5, each of the multiple individual optical elements 40 is a lens having positive refractive power. More specifically, the individual optical elements 40 shown in Figures 4 and 5 are plano-convex lenses having a convex surface on the -X side that is convex to the -X side and a flat surface on the +X side. The array optical element 4 according to the first example is a plano-convex lens array in which multiple plano-convex lenses are arranged in a first direction Y and a second direction Z. The multiple plano-convex lenses are integrally formed. The array optical element 4 according to the first example is composed of a glass material or resin material, etc., that is transparent to light L emitted from a light source 1.

[0034] The lenses as individual optical elements 40 are not limited to plano-convex lenses, but may be biconvex lenses, plano-concave lenses, biconcave lenses, meniscus lenses, etc., as long as they have refractive power. Furthermore, the lenses as individual optical elements 40 may include at least one of a spherical surface and an aspherical surface.

[0035] In the array optical element 4 according to the second example shown in Figure 6, each of the multiple individual optical elements 40 is a concave mirror. The array optical element 4 according to the second example is a concave mirror array in which multiple concave mirrors are arranged in a first direction Y and a second direction Z. The concave mirrors in the array optical element 4 according to the second example are arranged in a first direction Y and a second direction Z, similar to the plano-convex lenses in the array optical element 4 according to the second example in Figure 4. However, the array optical element 4 according to the first example transmits light L from the optical scanning unit 3, whereas the array optical element 4 according to the first example reflects light L from the optical scanning unit 3. Therefore, when using the array optical element 4 according to the second example, the retinal projection type image display device 50 needs to change the configuration and arrangement around the array optical element 4 in Figure 2 according to the above differences.

[0036] In the array optical element 4 according to the second example, the individual optical axis 40C of the individual optical element 40 is an axis that passes through the center of the individual optical element 40 and extends in the direction normal to the array optical element 4, for example, in the X direction. Figure 6 shows a cross-section of the array optical element 4 according to the second example, corresponding to the VV line in Figure 4. The mirrors as individual optical elements 40 are not limited to concave mirrors, but may be convex mirrors, etc., as long as they are mirrors with refractive power. Multiple concave mirrors are formed integrally. In addition, the mirrors as individual optical elements 40 may include spherical or aspherical surfaces. The array optical element 4 according to the second example is composed of a glass material, resin material, or metal material, etc., that can reflect light L emitted from the light source 1.

[0037] In this embodiment, the array optical element 4 has the function of making the exit angle of the light beam incident on each of the multiple individual optical elements 40 greater than the incident angle of the light beam. The function of such an array optical element 4 will be explained with reference to Figures 7 to 9. Figure 7 is a diagram showing the relationship between the incident focus angle θiX and the exit divergence angle θoX of the light beam LF in an individual optical element 40X of a retinal projection type image display device according to a comparative example. Figure 8 is a diagram showing the relationship between the incident focus angle θi and the exit divergence angle θo of the light beam LF in an individual optical element 40 of a retinal projection type image display device 50 according to this embodiment. Figure 9 is a diagram showing the relationship between the incident focus angle θiA and the exit divergence angle θoA of the light beam LF in an individual optical element 40A where the overall optical axis 50C and the individual optical axis 40AC overlap, and the relationship between the incident focus angle θiB and the exit divergence angle θoB of the light beam LF in an individual optical element 40B where the overall optical axis 50C and the individual optical axis 40BC do not overlap.

[0038] As shown in Figure 8, the incident focusing angle θi of the light beam LF represents the focusing angle of the light beam LF that is focused and incident on the individual optical elements 40. The exit divergence angle θo of the light beam LF represents the divergence angle of the light beam LF that is emitted from the individual optical elements 40.

[0039] The individual optical element 40X in the comparative example shown in Figure 7 is a positive thin lens with a focal length faX. For example, the individual optical element 40X is positioned at the focal point of the light beam LF that is focused onto the individual optical element 40X. In this case, the incident focus angle θiX and the exit divergence angle θoX are equal.

[0040] On the other hand, the individual optical element 40 according to this embodiment, shown in Figure 8, is a positive thin lens with a focal length fa. The individual optical element 40 differs from the comparative example in that it is positioned on the -X side of the focal point of the light beam LF that is focused and incident on the individual optical element 40. In this case, the light beam LF is refracted by the individual optical element 40, so that the exit divergence angle θo is larger than the incident focus angle θi. This allows the height to which light passes through the pupil in the observer's eyeball E to be increased. As a result, the eye box becomes larger. Note that if the individual optical element 40 is a negative thin lens, the eye box can be made larger by positioning the individual optical element 40 on the +X side of the focal point of the light beam LF that is focused and incident on the individual optical element 40.

[0041] In this embodiment, the array optical element 4 can increase the deflection angle of the light deflection unit 2. This makes it possible to provide a retinal projection type image display device 50 with a large eye box in this embodiment. Furthermore, in this embodiment, the retinal projection type image display device 50 can be miniaturized. In order to increase the eye box without significantly tilting the deflection surface of the light deflection unit 2, it is sufficient that the emission divergence angle θo is greater than the incidence focus angle θi at the position of the light deflection unit 2 where the light L emitted from the light source 1 is imaged by the first optical system 5.

[0042] In Figure 9, for individual optical elements 40B where the overall optical axis 50C and the individual optical axis 40BC do not overlap, the light beam LF is incident on the individual optical element 40B at an incident focus angle θiB and exits from the individual optical element 40B at an exit divergence angle θoB. For individual optical elements 40A where the overall optical axis 50C and the individual optical axis 40AC overlap, the light beam LF is incident on the individual optical element 40A at an incident focus angle θiA and exits from the individual optical element 40A at an exit divergence angle θoA. In this embodiment, by using the array optical element 4, individual optical elements 40 can be arranged for each field of view, and the light beam LF incident on the individual optical element 40B can reach the eyeball E.

[0043] In this embodiment, it is preferable to satisfy 0.02 < |fa| / D < 1. Hereinafter, fa is the focal length fa shown in Figure 8, and D is the maximum length D shown in Figure 4. For example, if |fa| / D is 1 or greater, the effect of widening the eye box is small. If |fa| / D is 0.02 or less, the light beam LF becomes too wide, and the depth of focus becomes shallow. By satisfying 0.02 < |fa| / D < 1, the eye box of the retinal projection type image display device 50 can be made larger, and the light beam LF incident on the eyeball E can be made narrower.

[0044] From the viewpoint of increasing the size of the eye box and directing a narrow beam of light LF onto the eyeball E, it is more preferable to satisfy 0.5 mm < |fa| < 5 mm, and even more preferable to satisfy 1 mm < |fa| < 3 mm.

[0045] The retinal projection image display device 50 has a first optical system 5 positioned in the optical path between the light source 1 and the light deflection unit 2, and having positive refractive power. Light L emitted from the light source 1 is imaged at the position of the light deflection unit 2 by the first optical system 5. This reduces aberrations due to the deflection of the light deflection unit 2, allowing light L from the light source 1 to enter the eyeball E. From the viewpoint of achieving high performance while remaining small and lightweight, it is preferable that the first optical system 5 includes one or two optical elements, each having refractive power.

[0046] The retinal projection image display device 50 has a second optical system 6 positioned in the optical path between the light deflection unit 2 and the light scanning unit 3, and having positive refractive power. The second optical system 6 focuses the light L diverging from the light deflection unit 2, allowing the light scanning unit 3 to be made smaller. From the viewpoint of achieving high performance while remaining compact and lightweight, it is preferable that the second optical system 6 includes one or two optical elements, each having refractive power.

[0047] The retinal projection image display device 50 has a third optical system 7 positioned in the optical path between the optical scanning unit 3 and the array optical element 4, and having positive refractive power. The third optical system 7 forms an image of the light source 1 at the position of the array optical element 4. This allows the amount of movement of the light beam position due to the deflection of the optical deflection unit 2 to be amplified by the array optical element 4. From the viewpoint of achieving high performance while being small and lightweight, it is preferable that the third optical system 7 includes one to three or fewer optical elements having refractive power.

[0048] The retinal projection image display device 50 has a fourth optical system 8 positioned in the optical path between the array optical element 4 and the retina, and having positive refractive power. The fourth optical system 8 can cause the image to be incident on the eyeball E at an appropriate virtual image distance. From the viewpoint of achieving high performance while remaining compact and lightweight, it is preferable that the fourth optical system 8 includes one or two optical elements, each having refractive power. Furthermore, the fourth optical system 8 is positioned so that the light deflection unit 2 and the eyeball E are in a conjugate relationship. This allows light L of the entire field of view to be incident on the eyeball E.

[0049] The retinal projection image display device 50 has a polarizing beam splitter 10 positioned in the optical path between the array optical element 4 and the retina. This allows for high light utilization efficiency while ensuring see-through properties. However, the polarizing beam splitter 10 is not limited to the optical path between the array optical element 4 and the retina, but may also be positioned in the optical path from the light source 1 to the retina. Positioning the polarizing beam splitter 10 in the optical path from the light source 1 to the retina increases light utilization efficiency. From the viewpoint of increasing light utilization efficiency, a quarter-wave plate may be used. Furthermore, by positioning the polarizing beam splitter in the optical path between the optical deflection unit 2 and the optical scanning unit 3, the overall optical axis 50C becomes perpendicular to the optical scanning unit 3, allowing a wider beam of light to be reflected by the deflection surface of the optical scanning unit 3, making it easier to widen the eye box.

[0050] The following describes in detail each component of the retinal projection type image display device 50.

[0051] (Light source 1) Light source 1 is a semiconductor laser that emits laser beams of one or more wavelengths. For example, light source 1 is composed of a red semiconductor laser, a green semiconductor laser, and a blue semiconductor laser. Light source 1 emits light L, which is time-modulated laser light, in response to a drive signal from the control unit of the retinal projection image display device 50. Because light source 1 includes a red semiconductor laser, a green semiconductor laser, and a blue semiconductor laser, the retinal projection image display device 50 can display a color image. However, the retinal projection image display device 50 can also display only a monochrome image. When displaying only a monochrome image, light source 1 may emit light of a single color.

[0052] The light intensity of the light L emitted from the light source 1 is preset to an appropriate light intensity that takes into full consideration the safety of the observer's eyes. However, the retinal projection type image display device 50 may be equipped with an optical element that reduces the light intensity of the light L as needed. The retinal projection type image display device 50 may also have a photodetector such as a photodiode that receives the light L emitted from the light source 1 and outputs a signal corresponding to the light intensity of the light L, and may control the light intensity of the light L based on the output signal of the photodetector to ensure the safety of the observer's eyes. The light intensity that ensures the safety of the observer's eyes refers to a light intensity below Class 1 as defined in the International Electrotechnical Commission (IEC) 60825-1, which is an international standard for the safety of laser light. Furthermore, the light source 1 is not limited to a semiconductor laser, but may also be a solid-state laser or a gas laser.

[0053] The retinal projection image display device 50 can change the light intensity of the light L emitted from the light source 1 by changing the current or voltage applied to the light source 1. This allows the retinal projection image display device 50 to adjust the brightness of the displayed image according to the brightness of the surrounding environment in which the retinal projection image display device 50 is used.

[0054] (Light deflector 2) Figure 10 is a schematic top view showing the optical deflection unit 2. In the example shown in Figure 10, the optical deflection unit 2 is a MEMS mirror capable of deflecting light in two axial directions. The optical deflection unit 2 has a deflection surface 14 on a movable part 101 connected to a support substrate 102. The optical deflection unit 2 can selectively switch the direction of light reflection by driving the movable part 101 and changing the orientation of the deflection surface 14. The optical deflection unit 2 is rotatable around the A axis along the β axis, and its orientation can be controlled at any position within the movable range by a drive voltage signal. Furthermore, the optical deflection unit 2 is also rotatable around the B axis along the α axis, and its orientation can be controlled at any position within the movable range by a drive voltage signal. In other words, within the movable range, the optical deflection unit 2 can reflect light L incident from the first optical system 5 to any position in the αβ plane. The optical deflection unit 2 is also positioned in the optical path between the light source 1 and the optical scanning unit 3.

[0055] The light deflection unit 2 includes a movable part 101 that reflects incident light L, and a support substrate 102 that supports a first member 110, a second member 120, a third member 130, and a fourth member 140, each having piezoelectric drive units (113a, 113b, 113c, 113d) connected to the movable part 101 that drive the movable part 101. The light deflection unit 2 also includes a connecting part 102a that connects the first member 110 and the movable part 101, a connecting part 102b that connects the second member 120 and the movable part 101, a connecting part 102c that connects the third member 130 and the movable part 101, a connecting part 102d that connects the fourth member 140 and the movable part 101, and electrode connecting parts 150a to 150h that electrically connect the piezoelectric drive units (113a, 113b, 113c, 113d) to the control device.

[0056] In the optical deflection section 2 shown in Figure 10, a single SOI substrate is formed by etching or other processes, and the deflection surface 14, piezoelectric drive sections (113a, 113b, 113c, 113d), electrode connection sections 150a to 150h, etc. are formed on the formed substrate, thereby integrally forming each component. Note that the formation of each component may be performed after the SOI substrate is formed, or during the SOI substrate is formed.

[0057] SOI substrates are substrates 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 provided on the silicon oxide layer. Because the silicon active layer is thinner in the γ direction than in the α or β direction, a component composed solely of the silicon active layer functions as an elastic part with elasticity. SOI substrates do not necessarily have to be planar and may have curvature, etc. Furthermore, any substrate that can be integrally molded by etching or the like and can be partially elasticized is not limited to SOI substrates as a component used to form MEMS mirrors.

[0058] The deflection surface 14 is composed of a thin metal film containing, for example, aluminum, gold, or silver. The movable part 101 may also have ribs for reinforcing the movable part formed on the -γ side surface of the movable part base 103. The ribs are composed of, for example, a silicon support layer 124 and a silicon oxide layer 125, and can suppress the distortion of the deflection surface 14 caused by movement.

[0059] The shape or configuration of the first member 110, the second member 120, the third member 130, and the fourth member 140 may be, for example, a meander structure or a cantilever structure. In addition, the first member 110, the second member 120, the third member 130, and the fourth member 140 may have some kind of sensor formed in addition to the piezoelectric drive unit (113a, 113b, 113c, 113d). The sensor may be, for example, a displacement detection sensor (piezoelectric, strain resistance, etc.) that outputs a signal in accordance with the deformation of the member, or a temperature sensor, etc.

[0060] The details of the shape of the connecting parts (102a, 102b, 102c, 102d) that connect the member and the movable part 101 are not limited to the configuration shown in Figure 10. Furthermore, it is desirable that the angle formed by the straight lines between the centers of the connecting parts (102a, 102b, 102c, 102d) and the movable part 101 be approximately 90 degrees in a plan view. However, it is not limited to this. In addition, the piezoelectric drive units (113a, 113b, 113c, 113d) may have functions other than driving. For example, the drive units may have functions such as displacement detection, heating, or electrical wiring.

[0061] The piezoelectric drive system for the piezoelectric drive units (113a, 113b, 113c, 113d) is a piezoelectric drive system. However, the drive system for the piezoelectric drive units (113a, 113b, 113c, 113d) is not limited to a piezoelectric drive system. For example, an electromagnetic drive system that deforms the support unit using an electromagnetic field, an electrostatic drive system in which comb-tooth electrodes are formed on the support unit, or a thermoelectric drive system that utilizes the difference in thermal expansion of different materials may be used. Coils or magnet arrays may be formed on the support substrate 102. Among these, the piezoelectric drive system is preferred from the viewpoint of efficiently arranging the piezoelectric drive units (113a, 113b, 113c, 113d) and suppressing an increase in the overall size of the optical deflection unit 2. For example, in the electrostatic drive system, comb-tooth electrodes are arranged on the outer circumference of the drive unit, which tends to increase the overall size of the movable mirror. Also, in the electromagnetic drive system, it is difficult to arrange the wiring layout to each of the multiple drive units and to arrange the magnets so that a magnetic field is applied to each, which tends to increase the overall size of the movable mirror. Furthermore, the piezoelectric drive units (113a, 113b, 113c, 113d) are not limited to being arranged only on one surface (the +γ side) of the elastic silicon active layer 126, but may also be arranged on other surfaces of the elastic layer (for example, the -γ side), or on both one and the other surface of the elastic layer.

[0062] An insulating layer made of silicon oxide film may be placed on at least one of the +γ side surfaces of the upper electrodes of the piezoelectric drive units (113a, 113b, 113c, 113d) or on the +γ side surface of the support substrate 102. In this case, electrode wiring may be placed on the insulating layer, and the insulating layer may be partially removed or omitted as an opening only at the connection spots where the upper or lower electrodes are connected to the electrode wiring. This increases the design flexibility of the piezoelectric drive units (113a, 113b, 113c, 113d) and electrode wiring, and further suppresses short circuits caused by contact between electrodes.

[0063] The silicon oxide film in the light deflection section 2 also functions as an anti-reflective material. When a positive or negative voltage is applied in the polarization direction to the piezoelectric section of each piezoelectric drive section (113a, 113b, 113c, 113d), deformation (e.g., expansion and contraction) proportional to the potential of the applied voltage occurs, exhibiting a so-called inverse piezoelectric effect. Due to the action of this deformation of the piezoelectric section, the piezoelectric drive sections (113a, 113b, 113c, 113d) are bent, and a driving force around the rotation axis acts on the movable section 101 via the connecting section (102a, 102b, 102c, 102d), causing the movable section 101 to move around the rotation axis of the A axis parallel to the β axis or the B axis parallel to the α axis.

[0064] The first member 110 is positioned at approximately 45 degrees to both the A-axis and the B-axis. In other words, the rotation of the movable part 101 due to the oscillation of the first member 110, the second member 120, the third member 130, and the fourth member 140 all have vectors in both the A-axis and the B-axis. For example, when voltage is applied to the piezoelectric drive units (113a, 113b) but not to the piezoelectric drive units (113c, 113d), the movable part 101 tilts around the rotation axis of the B-axis. Similarly, when voltage is applied to the piezoelectric drive units (113a, 113d) but not to the piezoelectric drive units (113c, 113d), the movable part 101 tilts around the A-axis as the center of rotation. In particular, when a drive frequency that does not match the structurally specific resonant frequency is used, the rotation direction of the movable part 101 can be arbitrarily controlled by the drive signal. In other words, by controlling the independent or combined drives of each piezoelectric drive unit (113a, 113b, 113c, 113d), the movable part 101 can be swung in a desired direction, enabling vector scanning.

[0065] The reference voltage of the piezoelectric drive units (113a, 113b, 113c, 113d) may be 0V, or any voltage within the maximum amplitude of the applicable voltage. The reference voltage may also differ between the piezoelectric drive units (113a, 113b, 113c, 113d). The signal waveform of the applied voltage may be a periodic waveform such as a sine wave, square wave, or sawtooth wave, or a more complex periodic waveform. The piezoelectric drive units (113a, 113b, 113c, 113d) may be DC driven.

[0066] The optical deflection unit 2 is not limited to a MEMS mirror capable of optical deflection in two axes, but may also be configured using two single-axis MEMS mirrors. However, using a vector scan MEMS mirror is preferable because it allows for miniaturization and weight reduction of the retinal projection type image display device 50. Alternatively, a configuration using one single-axis MEMS mirror is also possible.

[0067] (Optical scanning unit 3) Figure 11 is a schematic top view showing the optical scanning unit 3. In the example shown in Figure 11, the optical scanning unit 3 includes a support substrate 91, a movable part 92, a meandering beam part 93, a meandering beam part 94, and an electrode connection part 95.

[0068] The optical scanning unit 3 has a deflection surface 30 on a movable part 92 connected to a support substrate 91. The optical scanning unit 3 scans the reflected light of light L incident on the deflection surface 30 by oscillating the movable part 92 to change the angle of the deflection surface 30. By scanning the reflected light of light L, the optical scanning unit 3 draws pixels continuously in time using the scanning light Ls.

[0069] The meandering beam section 93 is formed in a meandering manner with multiple folded sections, one end connected to the support base plate 91 and the other end connected to the movable section 92. The meandering beam section 93 comprises a beam section 93a containing three beams and a beam section 93b containing three beams. The beams of beam section 93a and beam section 93b are formed alternately, one beam at a time. Each of the multiple beams included in beam section 93a and beam section 93b is independently equipped with a piezoelectric member. The number of beams included in beam section 93a is not limited to three and may be any number.

[0070] The meandering beam section 94 is formed in a meandering manner with multiple folded sections, one end connected to the support base plate 91 and the other end connected to the movable section 92. The meandering beam section 94 comprises a beam section 94a containing three beams and a beam section 94b containing three beams. The beams of beam section 94a and beam section 94b are formed alternately, one beam at a time. Each of the multiple beams included in beam section 94a and beam section 94b is independently equipped with a piezoelectric member. The number of beams included in beam section 93b is not limited to three and may be any number.

[0071] The piezoelectric members provided in beam sections 93a, 93b, 94a, and 94b are provided as piezoelectric layers in a part of the layers of each beam, which is formed in a multilayer structure, for example. Hereinafter, the piezoelectric members provided in beam sections 93a and 94a may be referred to as piezoelectric member 95a, and the piezoelectric members provided in beam sections 93b and 94b may be referred to as piezoelectric member 95b. When voltage signals with opposite phases are applied to piezoelectric members 95a and 95b, causing the meandering beam section 94 to bend, adjacent beam sections will bend in different directions. This bending accumulates, generating a rotational force that causes the deflection surface 30 to reciprocate around the A axis parallel to the β direction.

[0072] The movable part 92 is formed so as to be sandwiched between the meandering beam section 93 and the meandering beam section 94 in the β direction. The movable part 92 comprises a deflection surface 30, a torsion bar 92b, a piezoelectric member 92c, and a support section 92d.

[0073] The deflection surface 30 is formed, for example, by depositing a thin metal film containing aluminum, gold, silver, etc., onto a substrate. The torsion bar 92b has one end connected to the deflection surface 30 and extends in the positive and negative α directions to rotatably support the deflection surface 30.

[0074] The piezoelectric member 92c is connected at one end to the torsion bar 92b and at the other end to the support portion 92d. When a voltage is applied to the piezoelectric member 92c, it bends and deforms, causing a twist in the torsion bar 92b. This twist in the torsion bar 92b becomes a rotational force, causing the deflection surface 30 to rotate around the B axis, which is parallel to the α direction.

[0075] Rotation of the deflection surface 30 around the A axis causes the light L incident on the deflection surface 30 to be scanned in the α direction. Rotation of the deflection surface 30 around the B axis causes the light L incident on the deflection surface 30 to be scanned in the β direction.

[0076] The support portion 92d is formed to surround the deflection surface 30, 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 indirectly supports the torsion bar 92b, which is connected to the piezoelectric member 92c, and the deflection surface 30.

[0077] The support base plate 91 is formed to surround the movable part 92, the meandering beam part 93, and the meandering beam part 94. The support base plate 91 is connected to and supports the meandering beam part 93 and the meandering beam part 94. The support base plate 91 indirectly supports the movable part 92, which is connected to the meandering beam part 93 and the meandering beam part 94.

[0078] The optical scanning unit 3 is a MEMS mirror formed by microfabrication of silicon or glass, for example, using micromachining technology. Micromachining technology allows for the formation of highly accurate, movable miniature mirrors on a substrate, integrated with drive units such as serpentine beams. Specifically, for example, a single SOI (Silicon On Insulator) substrate is formed by etching or the like. On the formed substrate, a reflective mirror, serpentine beams, piezoelectric members, electrode connection parts, etc., are integrally formed to form a MEMS mirror. Note that the formation of the reflective mirror, etc., may be performed after the SOI substrate is formed, or it may be performed during the SOI substrate formation.

[0079] SOI substrates are substrates 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 provided on the silicon oxide layer. Because the silicon active layer is thinner in the γ direction than in the α or β direction, a component composed solely of the silicon active layer functions as an elastic part with elasticity. SOI substrates do not necessarily have to be planar and may have curvature, etc. Furthermore, any substrate that can be integrally molded by etching or the like and can be partially elasticized is not limited to SOI substrates as a component used to form MEMS mirrors.

[0080] The optical scanning unit 3 is not limited to a configuration using one two-axis MEMS mirror, as long as it can scan light in two axial directions. For example, the optical scanning unit 3 may be configured to use two one-axis MEMS mirrors. Furthermore, optical elements capable of scanning light, such as polygon mirrors or galvanometer mirrors, may be used, or these may be used in combination. However, using MEMS mirrors is preferable because it allows for miniaturization and weight reduction of the retinal projection type image display device 50. In particular, a configuration using only one MEMS mirror is even more preferable because it allows for miniaturization and weight reduction of the retinal projection type image display device 50. The driving method for the MEMS mirror may be electrostatic, piezoelectric, or electromagnetic.

[0081] (First optical system 5, second optical system 6, and third optical system 7) Each lens in the first optical system 5, the second optical system 6, and the third optical system 7 is made of a glass material or resin material, etc., having a transmittance of 60% or more to light L emitted from the light source 1. Each lens in the first optical system 5, the second optical system 6, and the third optical system 7 is not limited to one, but may be in multiple quantities. Furthermore, the first optical system 5, the second optical system 6, and the third optical system 7 may include lenses of various forms, such as spherical lenses, aspherical lenses, Fresnel lenses, and diffractive lenses. In addition, the first optical system 5, the second optical system 6, and the third optical system 7 may include optical elements other than lenses, such as mirrors. From the viewpoint of reducing flare and ghosting, it is preferable that in each of the first optical system 5, the second optical system 6, and the third optical system 7, a reflection-reducing film that reduces the reflection of light L is applied to surfaces other than those that are intentionally reflected.

[0082] (4th optical system 8) The concave mirror of the fourth optical system 8 is made up of a glass material, resin material, or metal material, etc., that can reflect the light L emitted from the light source 1. However, the fourth optical system 8 is not limited to a concave mirror and may be made up of one or more optical elements.

[0083] (Polarizing beam splitter 10) A cube-shaped polarizing beam splitter 10 can be used. The polarizing beam splitter 10 is composed of, for example, a glass material that is transparent to light L emitted from the light source 1. From the viewpoint of reducing flare light and ghost light, it is preferable that a reflection-reducing film that reduces the reflection of light L is applied to the surfaces of the polarizing beam splitter 10 other than the surface that is intentionally used for reflection.

[0084] (Control Unit 9) The retinal projection image display device 50 has a control unit 9 that controls the operation of the light source 1, the light deflection unit 2, the light scanning unit 3, etc. The control unit 9 is connected to each of the light source 1, the light deflection unit 2, and the light scanning unit 3 via wired or wireless communication. The control unit 9 receives image data that will be the basis of the overall image to be formed, and controls the emission of light L from the light source 1 based on the input image data. The control unit 9 also deflects the light L emitted from the light source 1 using the light deflection unit 2, and the light scanning unit 3 scans the light L deflected by the light deflection unit 2 using the deflection surface 30 to form an image.

[0085] (Hardware configuration of control unit 9) Figure 12 is a block diagram showing the hardware configuration of the control unit 9. The control unit 9 includes a CPU (Central Processing Unit) 911, a ROM (Read Only Memory) 912, a RAM (Random Access Memory) 913, a light source drive circuit 914, a scanning drive circuit 915, and a deflection drive circuit 916. These are electrically connected to each other via the system bus B.

[0086] The CPU 911 is an arithmetic unit that reads programs and data from storage devices such as the ROM 912 onto the RAM 913, executes processing, and realizes the overall control and functions of the control unit 9. The ROM 912 is a non-volatile storage device that can retain programs and data even when the power is turned off. The ROM 912 stores processing programs and data that the CPU 911 executes to control each function of the retinal projection image display device 50d. The RAM 913 is a volatile storage device that temporarily holds programs and data.

[0087] The light source drive circuit 914 is an electrical circuit that drives the light source 1 by applying current or voltage to it. The light source 1 turns the emission of light L ON or OFF and changes the light intensity of the emitted light L in response to the drive signal D1 output from the light source drive circuit 914.

[0088] The scanning drive circuit 915 is an electrical circuit that applies voltage to drive the optical scanning unit 3. The optical scanning unit 3 changes the angle of the deflection surface 30 provided by the movable unit 92 in accordance with the drive signal D2 output from the scanning drive circuit 915.

[0089] The deflection drive circuit 916 is an electrical circuit that applies voltage to drive the optical deflection unit 2. The optical deflection unit 2 changes the inclination angle of the deflection surface 14 provided by the movable unit 101 in accordance with the drive signal D3 output from the deflection drive circuit 916.

[0090] The External I / F917 is an interface for connecting to external devices and networks. External devices include, for example, higher-level devices such as PCs (Personal Computers), and storage devices such as USB (Universal Serial Bus) memory, SD cards, CDs, DVDs, HDDs, and SSDs. Networks include, for example, automotive CAN (Controller Area Network), LAN (Local Area Network), and the Internet. The External I / F917 only needs to be configured to enable connection or communication with external devices, and an External I / F917 may be provided for each external device.

[0091] In the control unit 9, the CPU 911 acquires image data from external devices or networks via the external I / F 917. The CPU 911 can acquire video information as long as it is configured to do so. This may involve storing the image data in the ROM 912 within the control unit 9, or by adding a storage device such as an SD card within the control unit 9 and storing the image data in that device.

[0092] (Functional configuration of the control unit 9) Figure 13 is a block diagram showing the functional configuration of the control unit 9. The control unit 9 includes a light source control unit 902, a scanning control unit 903, and a deflection control unit 904. The control unit 9 may also have a function to correct distortions, etc., if the image viewed by the observer has distortions, etc.

[0093] The functions of the light source control unit 902, the scanning control unit 903, and the deflection control unit 904 can be realized by the external I / F 917 and the CPU 911 executing processes specified in a program stored in the ROM 912. Some of the functions of the light source control unit 902 may be realized by the light source drive circuit 914. Some of the functions of the scanning control unit 903 may be realized by the scanning drive circuit 915. Some of the functions of the deflection control unit 904 may be realized by the deflection drive circuit 916. The functions of the light source control unit 902, the scanning control unit 903, and the deflection control unit 904 may be included in a configuration other than the control unit 9. For example, an external device such as a microcontroller or PC that can communicate with the control unit 9 may have at least some of the functions of the estimation unit 901, the light source control unit 902, the scanning control unit 903, and the deflection control unit 904.

[0094] Each function of the control unit 9 can also be implemented by one or more processing circuits. These processing circuits may include ASICs (Application Specific Integrated Circuits), FPGAs (Field-Programmable Gate Arrays), DSPs (Digital Signal Processors), or electrical circuits capable of executing the above-mentioned functions. Furthermore, some of the functions of the control unit 9 may be implemented by an external device such as a microcontroller or PC that is connected to the control unit 9 in a communicative manner. Additionally, some of the functions of the control unit 9 may be implemented through distributed processing between the control unit 9 and the external device.

[0095] The light source control unit 902 drives the light source 1. The scanning control unit 903 outputs a drive signal D2 to the optical scanning unit 3 to drive the optical scanning unit 3. The deflection control unit 904 outputs a drive signal D3 to the optical deflection unit 2 to drive the optical deflection unit 2.

[0096] <Example of placement of the retinal projection image display device 50 on the support 100> Figure 14 is a schematic top view showing a first example of the placement position of the retinal projection image display device 50 on the support 100. Figure 14 shows the placement position of the retinal projection image display device 50 on the support 100 worn by the observer.

[0097] In the first example shown in Figure 14, among the components of the retinal projection image display device 50, the fourth optical system 8 is located on the frame 153, for example, on the +Y side. The components of the retinal projection image display device 50 other than the fourth optical system 8 are located outside the temple 151, for example, on the -X side. The fourth optical system 8 may also be located on the +X side, -X side, or -Y side of the frame 153.

[0098] Figure 15 is a schematic top view showing a second example of the placement position of the retinal projection image display device 50 on the support 100. Figure 15 shows the placement position of the retinal projection image display device 50 on the support 100 worn by the observer.

[0099] In the second example shown in Figure 15, the retinal projection image display device 50 is positioned on the outside of the support 100 worn by the observer, for example, on the -X side. This arrangement allows the observer to view the outside world through the support 100 while simultaneously viewing the image displayed by the retinal projection image display device 50.

[0100] [Second Embodiment] Next, a retinal projection image display device according to the second embodiment will be described with reference to Figures 16 and 17. Note that names and reference numerals identical to those used in the previously described embodiments indicate the same or identical components or configurations, and detailed explanations will be omitted as appropriate. This also applies to the embodiments described hereafter.

[0101] Figure 16 is a schematic top view showing a retinal projection type image display device 50a according to the second embodiment. Figure 17 is a block diagram showing the functional configuration of the control unit 9a of the retinal projection type image display device 50a.

[0102] The retinal projection image display device 50a according to this embodiment differs from the retinal projection image display device 50 according to the first embodiment in that it includes a detection unit 13 for detecting the position of the observer's pupil or cornea, and a control unit 9a for controlling the operation of the light deflection unit 2 so that the position of the image formed by the light scanning unit 3 changes according to the detection result of the detection unit 13.

[0103] (Detection unit 13) In the example shown in Figure 16, the detection unit 13 includes a detection light source 131 that emits detection light S1 toward the cornea K of the eyeball E, and a detection light receiving unit 132 that receives the reflected light S2 from the eyeball E of the detection light S1 emitted from the detection light source 131. In the example shown in Figure 16, for the sake of clarity, the detection light source 131 and the detection light receiving unit 132 are arranged near the eyeball E, but the arrangement of the detection light source 131 and the detection light receiving unit 132 can be selected as appropriate. Also, in Figure 16, the reference numerals for the detection unit 13 and the detection light source 131 are shown together, and the reference numerals for the detection unit 13 and the detection light receiving unit 132 are also shown together, to indicate that the detection unit 13 has a detection light source 131 and a detection light receiving unit 132. In subsequent examples, reference numerals for multiple components may be shown together for the same purpose.

[0104] The detection light source 131 can be an array light source having multiple light-emitting parts such as a vertical cavity surface-emitting laser (VCSEL), an LDA (Laser Diode Array), or an LED (Light Emitting Diode), or a semiconductor laser that emits laser beams of one or more wavelengths.

[0105] The wavelength of the detection light S1 emitted from the detection light source 131 is preferably a near-infrared wavelength, which is invisible light, so as not to obstruct the view of the observer whose line of sight is being detected. However, it is not limited to invisible light and may be visible light. The detection light source 131 is positioned so that the emitted detection light S1 is incident on the cornea K of the eyeball E.

[0106] The detection light receiving unit 132 is at least one photodiode that outputs a detection signal corresponding to the light intensity of the reflected light S2 received. However, the detection light receiving unit 132 may be a position detection element such as a PSD (Position Sensitive Detector), or an image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor).

[0107] The surface of the cornea K, which is the surface of the observer's eyeball E, is a transparent material containing water and typically has a reflectivity of about 2-4%. The detection light S1 incident on the cornea K is reflected by the surface of the cornea K and incident on the detection light receiving unit 132.

[0108] (Control Unit 9a) The control unit 9a is connected to the detection unit 13 via wired or wireless communication. The control unit 9a controls the emission of detection light S1 from the detection light source 131. The control unit 9a also controls the deflection angle of light L by the light deflection unit 2 based on the emission timing of each light-emitting part in the detection light source 131 and the position of the observer's pupil P or cornea K detected based on the light-receiving signal from the detection light-receiving unit 132.

[0109] (Functional configuration of the control unit 9a) Figure 17 is a block diagram showing the functional configuration of the control unit 9a. The control unit 9a differs from the control unit 9 in the retinal projection type image display device 50 according to the first embodiment in that it has an estimation unit 901. The hardware configuration of the control unit 9 can be the one shown in Figure 12.

[0110] The functions of the estimation unit 901 can be realized by the external I / F 917 shown in Figure 12, and by the CPU 911 executing processes defined in the program stored in the ROM 912. The functions of the estimation unit 901 may also be included in a configuration other than the control unit 9. For example, an external device such as a microcontroller or PC that can communicate with the control unit 9 may have the functions of the estimation unit 901.

[0111] The estimation unit 901 estimates the position of the observer's cornea K based on the light emission timing of each light-emitting part of the detection light source 131 and the detection signal output from the detection light receiving unit 132. The estimation unit 901 acquires image data Im obtained from an external device and converts the image data into a control signal based on the information regarding the position of the cornea K estimated by the estimation unit 901, and outputs it to the light source control unit 902, the scanning control unit 903, and the deflection control unit 904, respectively.

[0112] The light source control unit 902 drives the light source 1 and the detection light source 131 by outputting a drive signal D1 to the light source 1 and a drive signal D4 to the detection light source 131, respectively, based on the control signal input from the estimation unit 901. The scanning control unit 903 drives the optical scanning unit 3 by outputting a drive signal D2 to the optical scanning unit 3, based on the control signal input from the estimation unit 901. The deflection control unit 904 drives the optical deflection unit 2 by outputting a drive signal D3 to the optical deflection unit 2, based on the control signal input from the estimation unit 901.

[0113] (Effects of the retinal projection type image display device 50a) For example, if the observer's eyes tilt in response to a change in their gaze, the image displayed by the retinal projection image display device may shift relative to the observer's field of view, making it impossible to display the image in the desired position within the observer's field of view.

[0114] In this embodiment, the detection unit 13 detects the position of the observer's pupil or cornea, and the control unit 9a controls the operation of the light deflection unit 2 so that the position of the image formed by the light scanning unit 3 changes according to the detection result by the detection unit 13. As a result, the retinal projection image display device 50a reduces the displacement of the displayed image relative to the observer's field of view even when the observer's eyeball is tilted, and can display the image at a desired position in the observer's field of view.

[0115] [Examples] The following describes specific embodiments of the present invention. However, the present invention is not limited to these examples.

[0116] (Example 1) Figure 18 is a schematic diagram showing a retinal projection type image display device 50b according to Embodiment 1. In Embodiment 1, the deflection surface 30 of the optical scanning unit 3 shown in Figure 11 can be tilted by a maximum of ±6 degrees by rotation around the B axis in Figure 11 as the rotation center. When the deflection surface 30 of the optical scanning unit 3 is tilted by a maximum of ±6 degrees, the maximum field of view corresponding to the lateral direction of the image formed by the optical scanning unit 3 becomes approximately 24 degrees.

[0117] In Example 1, the individual optical elements 40 of the array optical element 4 are lenses. The lenses have a radius of curvature of 1 mm and a focal length fa of 2.05 mm. The distance between the centers of adjacent individual optical elements 40 in a plurality of individual optical elements 40 may be equal, and may not be equal by more than 1. The center of the array optical element 4 is the center of the field of view, and the outermost edge is located at 5.03 mm. The relationship between the focal length fa and the maximum length D is |fa| / D = 0.20. Furthermore, in the retinal projection type image display device 50b, when the deflection surface 14 of the light deflection unit 2 is tilted by 1 degree by rotation around the B axis in Figure 10, the position of the light beam at the center of the field of view moves by 0.87 mm at the position of the eyeball.

[0118] In Example 1, the array optical element 4 has an arrangement area 41 that is approximately circular in plan view, as shown in Figure 4. The diameter of this arrangement area 41 in plan view is φ10.4 mm. In Example 1, each individual optical element 40 in the array optical element 4 is arranged on a virtual plane, but they may also be arranged on a virtual curved surface with curvature.

[0119] (Example 2) Figure 19 is a schematic diagram showing the retinal projection type image display device 50c according to Example 2. The retinal projection type image display device 50c mainly differs from the retinal projection type image display device 50b according to Example 1 in that it has a prism 12.

[0120] In Example 2, the deflection surface 30 of the optical scanning unit 3 shown in Figure 11 can be tilted by up to ±6 degrees by rotation around the B axis in Figure 11. When the deflection surface 30 of the optical scanning unit 3 is tilted by up to ±6 degrees, the maximum field of view corresponding to the lateral direction of the image formed by the optical scanning unit 3 becomes approximately 24 degrees.

[0121] In Example 2, the individual optical elements 40 of the array optical element 4 are lenses. The lenses have a radius of curvature of 0.7 mm and a focal length fa of 1.44 mm. The distance between the centers of adjacent individual optical elements 40 in the multiple individual optical elements 40 may be equal, and may not be equal by 1 or more. The center of the array optical element 4 is the center of the field of view, and the outermost edge is located at 5.03 mm. The relationship between the focal length fa and the maximum length D is |fa| / D = 0.14. Furthermore, in the retinal projection type image display device 50c, when the deflection surface 14 of the light deflection unit 2 is tilted by 1 degree by rotation around the B axis in Figure 10, the position of the light beam at the center of the field of view moves by 0.95 mm at the position of the eyeball.

[0122] In Example 2, the array optical element 4 has an arrangement area 41 that is approximately circular in plan view, as shown in Figure 4. The diameter of this arrangement area 41 in plan view is φ10.4 mm. In Example 2, each individual optical element 40 in the array optical element 4 is arranged on a virtual plane, but they may also be arranged on a virtual curved surface with curvature.

[0123] (Example 3) Figure 20 is a schematic diagram showing a retinal projection type image display device 50d according to Embodiment 3. In Embodiment 3, the deflection surface 30 of the optical scanning unit 3 shown in Figure 11 can be tilted by up to ±6 degrees by rotation around the B axis in Figure 11 as the rotation center. When the deflection surface 30 of the optical scanning unit 3 is tilted by up to ±6 degrees, the maximum field of view corresponding to the lateral direction of the image formed by the optical scanning unit 3 becomes approximately 24 degrees.

[0124] In Example 3, the individual optical elements 40 of the array optical element 4 are lenses. The lenses have a radius of curvature of 3.0 mm and a focal length fa of -4.1 mm. The distance between the centers of adjacent individual optical elements 40 in the multiple individual optical elements 40 may all be equal, and at least 1 of them may not be equal. The center of the array optical element 4 is the center of the field of view, and the outermost edge is located at 5.47 mm. The relationship between the focal length fa and the maximum length D is |fa| / D = 0.36. Furthermore, in the retinal projection type image display device 50d, when the deflection surface 14 of the light deflection unit 2 is tilted by 1 degree by rotation around the B axis in Figure 10, the position of the light beam at the center of the field of view moves by 0.95 mm at the position of the eyeball.

[0125] In Example 3, the array optical element 4 has an arrangement area 41 that is approximately circular in plan view, as shown in Figure 4. The diameter of this arrangement area 41 in plan view is φ11.4 mm. In Example 3, each individual optical element 40 in the array optical element 4 is arranged on a virtual plane, but they may also be arranged on a virtual curved surface with curvature.

[0126] (Example 4) Figure 21 is a schematic diagram showing a retinal projection type image display device 50e according to Embodiment 4. The retinal projection type image display device 50e includes an optical scanning unit 3 which comprises a first optical scanning unit 31 and a second optical scanning unit 32. The first optical scanning unit 31 scans light deflected by the optical deflection unit 2, and the second optical scanning unit 32 scans the light scanned by the first optical scanning unit 31. This is the main difference from the retinal projection type image display device 50b according to Embodiment 1. The configuration of the optical scanning unit 3 shown in Figure 11 can be applied to each of the first optical scanning unit 31 and the second optical scanning unit 32.

[0127] In Embodiment 4, lens 15, two cube beam splitters 18, and lens 16 are arranged in the optical path between the first optical scanning unit 31 and the second optical scanning unit 32. Lens 16 and a cube beam splitter 18 are arranged in the optical path between the second optical scanning unit 32 and the array optical element 4. Lens 17 is arranged in the optical path between the array optical element 4 and the retina. The reflective surface 19 reflects light from the cube beam splitter 18 back towards the cube beam splitter 18.

[0128] In Example 4, the deflection surface 30 of the first optical scanning unit 31 shown in Figure 11 can be tilted by a maximum of ±4 degrees by rotation around the A-axis in Figure 11. The deflection surface 30 of the second optical scanning unit 32 does not tilt when rotated around the A-axis in Figure 11. Because the deflection surface 30 of the first optical scanning unit 31 is tilted by a maximum of ±4 degrees, the maximum field of view corresponding to the vertical direction of the image formed by the first optical scanning unit 31 is approximately 16 degrees.

[0129] Furthermore, in Example 4, the deflection surface 30 of the first optical scanning unit 31 shown in Figure 11 can be tilted by a maximum of ±6 degrees by rotation around the B axis in Figure 11. The deflection surface 30 of the second optical scanning unit 32 can be tilted by a maximum of ±3 degrees by rotation around the B axis in Figure 11. When the deflection surface 30 of the first optical scanning unit 31 is tilted by a maximum of ±6 degrees, the maximum field of view corresponding to the lateral direction of the image formed by the first optical scanning unit 31 becomes approximately 24 degrees. When the deflection surface 30 of the second optical scanning unit 32 is tilted by a maximum of ±3 degrees, the maximum field of view corresponding to the lateral direction of the image formed by the second optical scanning unit 32 becomes approximately 12 degrees.

[0130] For example, if an image is formed by the first optical scanning unit 31 and the position of the image is scanned by the second optical scanning unit 32, the vertical field of view of the image will be approximately 16 degrees, and the horizontal field of view of the image will be approximately 24 degrees. The range in which the second optical scanning unit 32 can scan the position of the image will be approximately 12 degrees in the horizontal direction. In addition, both the first optical scanning unit 31 and the second optical scanning unit 32 can be used to form an image.

[0131] In Example 4, the individual optical elements 40 of the array optical element 4 are lenses. The lenses have a radius of curvature of 0.5 mm and a focal length fa of 1.03 mm. The distance between the centers of adjacent individual optical elements 40 in a plurality of individual optical elements 40 may all be equal, and may not be equal by 1 or more. The center of the array optical element 4 is the center of the field of view, located 2.33 mm from the center at the vertical end and 5.30 mm from the center at the horizontal end.

[0132] In Example 4, the maximum length D of the arrangement area 41 shown in Figure 4 is 13 mm. The relationship between the focal length fa and the maximum length D is |fa| / D = 0.08. Also, in Example 4, when the deflection surface 14 of the light deflection unit 2 is tilted by 2 degrees by rotation around the A axis in Figure 10, the position of the light beam at the center of the field of view moves by 1.34 mm at the position of the eyeball.

[0133] In Example 4, the array optical element 4 has an arrangement area 41 that is approximately rectangular in plan view, as shown in Figure 4. The size of this arrangement area 41 in plan view is 5 mm × 12 mm. In Example 4, each individual optical element 40 in the array optical element 4 is arranged on a virtual plane, but they may also be arranged on a virtual curved surface with curvature.

[0134] (Example 5) Figure 22 is a schematic diagram showing a retinal projection type image display device 50f according to Example 5. In the retinal projection type image display device 50f, a polarizing beam splitter 20 is placed in the optical path between the optical scanning unit 3 and the array optical element 4, a right-angle prism 21 is placed in the optical path between the array optical element 4 and the retina, and a lens 22 is placed in the optical path between the right-angle prism 21 and the retina. This is the main difference from the retinal projection type image display device 50b according to Example 1.

[0135] In Example 5, the retinal projection image display device 50f has a polarizing beam splitter 20 and a right-angle prism 21, allowing the components to be arranged so that the array optical element 4 is not positioned between the eyeball and the external landscape. As a result, the observer can clearly see the external landscape without being affected by the array optical element 4.

[0136] Although preferred embodiments have been described in detail above, the present invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

[0137] The ordinal numbers, quantities, and other figures used in the description of the embodiments of the present invention are all illustrative to specifically illustrate the technology of the present invention, and the present invention is not limited to these illustrative figures. Furthermore, the connection relationships between the components are illustrative to specifically illustrate the technology of the present invention, and do not limit the connection relationships that realize the functions of the present invention.

[0138] Examples of the present invention are as follows: <1> A retinal projection image display device that projects an image onto the retina of an observer, comprising: a light source; a light deflection unit that deflects light emitted from the light source; a light scanning unit that scans the light deflected by the light deflection unit to form the image; and an array optical element arranged in the optical path between the light scanning unit and the observer's retina, which guides the light scanned by the light scanning unit to the observer's retina, wherein the array optical element includes a plurality of individual optical elements arranged in a first direction and a second direction intersecting the first direction, each having refractive power, and the individual optical axes of each of the plurality of individual optical elements are parallel to each other and intersect the first direction and the second direction, respectively. <2> The individual optical element is either a lens or a mirror. <1> This is a retinal projection type image display device as described above. <3> Let fa be the focal length of the individual optical element, and D be the maximum length of the arrangement region in which the multiple individual optical elements are arranged. Then the following satisfies 0.02 < |fa| / D < 1. <1> or the above <2> This is a retinal projection type image display device as described above. <4> The first optical system is arranged in the optical path between the light source and the light deflection unit and has a positive refractive power, and the light emitted from the light source is imaged at the position of the light deflection unit by the first optical system. <1> from the above <3> It is a retinal projection type image display device as described in any one of the following. <5> The first optical system includes one or two optical elements, each having refractive power, <4> This is a retinal projection type image display device as described above. <6> The optical path between the optical deflection unit and the optical scanning unit is arranged and has a second optical system having positive refractive power, <1> from the above <5> It is a retinal projection type image display device as described in any one of the following. <7> The second optical system includes one or two optical elements, each having refractive power, <6> This is a retinal projection type image display device as described above. <8> The optical path between the optical scanning unit and the array optical element is arranged and has a third optical system having positive refractive power, and the third optical system forms an image of the light source at the position of the array optical element. <1> from the above <7> It is a retinal projection type image display device as described in any one of the following. <9> The third optical system includes one to three optical elements, each having refractive power. <8> This is a retinal projection type image display device as described above. <10> The array optical element is positioned in the optical path between the observer's retina and has a fourth optical system having positive refractive power, <1> from the above <9> It is a retinal projection type image display device as described in any one of the following. <11> The fourth optical system includes one or two optical elements, each having refractive power, <10> This is a retinal projection type image display device as described above. <12> The optical path from the light source to the observer's retina has a polarizing beam splitter, <1> from the above <11> This is a retinal projection type image display device as described above. <13> The surface of the support worn by the observer is arranged <1> from the above <12> It is a retinal projection type image display device as described in any one of the following. <14> The following are included: a detection unit for detecting the position of the observer's pupil or cornea, and a control unit for controlling the operation of the light deflection unit so that the position of the image formed by the light scanning unit changes according to the detection result by the detection unit. <1> from the above <13> It is a retinal projection type image display device as described in any one of the following. <15> The optical scanning unit includes a first optical scanning unit and a second optical scanning unit, wherein the first optical scanning unit scans light deflected by the optical deflection unit, and the second optical scanning unit scans light scanned by the first optical scanning unit. <1> from the above <14> It is a retinal projection type image display device as described in any one of the following. [Explanation of Symbols]

[0139] 1 light source 2 Light deflection section 3. Optical scanning unit 4 Array Optical Elements 5 First optical system 6 Second optical system 7 Third optical system 8 4th optical system 9, 9a Control Unit 10 Polarizing Beam Splitter 13 Detection unit 14 Deflection surface 15, 16, 17 lenses 18 Cube Beam Splitter 19 Reflective surface 20 Polarizing Beam Splitter 21 Right-angle prism 22 lenses 30 Deflection surface 40 Individual Optical Elements 40C, 40AC, 40BC individual optical axis 41 Placement area 50, 50a, 50b, 50c, 50d, 50e, 50f Retinal projection image display device 50C overall optical axis 91 Support substrate 92 Moving parts 92b Torsion bar 92c Piezoelectric component 92d Support part 93a Beam section 93. Serpentine beam section 94. Serpentine beam section 95 Electrode connection part 100 support 102 Support substrate 102a, 102b, 102c, 102d connection part 113a, 113b, 113c, 113d Piezoelectric drive unit 110 First member 120 Second member 130 Third member 131 Detection light source 132 Light-receiving unit for detection 140 Fourth member 151 Crane 152 Light-transmitting material 153 frames 911 CPU 912 ROM 913 RAM 914 Light source driving circuit 915 Scanning drive circuit 916 Deflection Drive Circuit 917 External I / F 901 Estimation Department 902 Light source control unit 903 Scanning Control Unit 904 Deflection control section B System Bathroom D Maximum length D1, D2, D3, D4 drive signals E Eyeball fa focal length Im image data K cornea L light LF luminous flux S1 Detection light S2 reflected light θi, θiA, θiB Incident focusing angle θo, θoA, θoB: Outgoing divergence angles [Prior art documents] [Patent Documents]

[0140] [Patent Document 1] Japanese Patent Publication No. 2023-76137

Claims

1. A retinal projection type image display device that projects an image onto the observer's retina, Light source and A light deflection unit that deflects the light emitted from the light source, A light scanning unit that scans the light deflected by the light deflection unit to form the image, It includes an array optical element positioned in the optical path between the optical scanning unit and the observer's retina, which guides the light scanned by the optical scanning unit to the observer's retina. The array optical element includes a plurality of individual optical elements arranged in a first direction and a second direction intersecting the first direction, each having refractive power. A retinal projection type image display device in which the individual optical axes of each of the plurality of individual optical elements are parallel to each other and intersect in the first direction and the second direction, respectively.

2. The retinal projection type image display device according to claim 1, wherein the individual optical element is either a lens or a mirror.

3. Let fa be the focal length of the individual optical element. If D is the maximum length of the arrangement region in which the multiple individual optical elements are arranged, The retinal projection type image display device according to claim 1, satisfying 0.02 < |fa| / D < 1.

4. It has a first optical system arranged in the optical path between the light source and the light deflection unit, and having a positive refractive power. The retinal projection type image display device according to claim 1, wherein the light emitted from the light source is imaged at the position of the light deflection portion by the first optical system.

5. The retinal projection image display device according to claim 4, wherein the first optical system includes one or two optical elements, each having refractive power.

6. The retinal projection type image display device according to claim 1, comprising a second optical system having positive refractive power and arranged in the optical path between the light deflection unit and the light scanning unit.

7. The retinal projection image display device according to claim 6, wherein the second optical system includes one or two optical elements, each having refractive power.

8. It has a third optical system that is arranged in the optical path between the optical scanning unit and the array optical element and has a positive refractive power, The retinal projection type image display device according to claim 1, wherein the third optical system forms an image of the light source at the position of the array optical element.

9. The retinal projection type image display device according to claim 8, wherein the third optical system includes one to three optical elements, each having refractive power.

10. The retinal projection image display device according to claim 1, further comprising a fourth optical system having positive refractive power and arranged in the optical path between the array optical elements and the observer's retina.

11. The retinal projection image display device according to claim 10, wherein the fourth optical system includes one or two optical elements, each having refractive power.

12. The retinal projection type image display device according to claim 1, further comprising a polarizing beam splitter positioned in the optical path from the light source to the observer's retina.

13. The retinal projection type image display device according to claim 1, which is positioned on the outside of the support worn by the observer.

14. A detection unit for detecting the position of the observer's pupil or cornea, The retinal projection type image display device according to claim 1, further comprising: a control unit that controls the operation of the light deflection unit so that the position of the image formed by the light scanning unit changes according to the detection result of the detection unit.

15. The optical scanning unit includes a first optical scanning unit and a second optical scanning unit. The first optical scanning unit scans the light deflected by the optical deflection unit. The retinal projection type image display device according to claim 1, wherein the second optical scanning unit causes the light scanned by the first optical scanning unit to scan.

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