WO2017056802A1

WO2017056802A1 - Image projection device

Info

Publication number: WO2017056802A1
Application number: PCT/JP2016/074838
Authority: WO
Inventors: 荒川泰彦; 菅原充; 鈴木誠
Original assignee: 株式会社Ｑｄレーザ; 国立大学法人東京大学
Priority date: 2015-09-29
Filing date: 2016-08-25
Publication date: 2017-04-06
Also published as: JPWO2017056802A1; JP6209705B2

Abstract

An image projection device provided with a scanning unit for scanning, in a 2D direction, light rays emitted from a light source, an optical component for reflecting or transmitting the light rays scanned by the scanning unit, and a first mirror (24) that is disposed in front of an eyeball of user and that projects an image onto the retina by reflecting the light rays incident from the lateral direction and reflected or transmitted by the optical component and irradiating the light rays onto the retina of the eyeball, the first mirror having a first region (R1) and a second region (R2), the first region being positioned from the second region in the direction in which the light rays are incident on the first mirror, and the optical component makes the condensing power in a third region S1, which reflects or transmits, among the light rays scanned by the scanning unit, first light rays (L1) irradiated at the first region, to be greater than the condensing power in a fourth region (S2), which reflects or transmits, among the light rays scanned by the scanning unit, second light rays (L2) irradiated at the second region.

Description

Image projection device

The present invention relates to an image projection apparatus, for example, an image projection apparatus which projects an image directly onto a user's retina.

There is known an image projection apparatus such as a head mounted display (HMD) which directly projects an image onto a user's retina using a light beam emitted from a light source (Patent Document 1). In such an image projection apparatus, a method called Maxwell vision is used. In Maxwell vision, the rays forming the image are focused near the pupil and the image is projected onto the retina.

There is known an image projection apparatus that detects light reflected by the cornea and adjusts the in-focus position so that a light beam is focused on the retina (Patent Document 2). There is also known an image projection apparatus that reflects light emitted from a light source with two mirrors having different curvatures in a plane and irradiates the user's retina (Patent Documents 3 and 4).

International Publication No. 2014/192479 JP, 2009-258686, A JP 2008-46253 A WO 2004/029693

When a mirror is placed in front of the user's eye and light rays forming the image are focused near the pupil for Maxwell's vision, an area in which the in-focus position largely deviates from the retina occurs in the image. For example, if it is attempted to adjust the in-focus position by the method as described in Patent Document 2, the in-focus position is adjusted in synchronization with the scanning light beam to form an image. difficult.

The present invention has been made in view of the above problems, and an object thereof is to set the in-focus position to an appropriate position.

According to the present invention, a scanning unit for scanning a light beam emitted from a light source in a two-dimensional direction, an optical component for reflecting or transmitting the light beam scanned by the scanning unit, and an optical component disposed in front of a user's eye And a first mirror for projecting an image onto the retina by reflecting or transmitting a light beam reflected or transmitted to the retina of the eye, the first mirror having a first area and a second area The first region of the first mirror is positioned in a direction in which the light beam is incident from the second region, and the optical component irradiates the first region of the light beam scanned by the scanning unit. The condensing power in the third region for reflecting or transmitting one light beam is determined from the condensing power in the fourth region for reflecting or transmitting the second light beam irradiated to the second region among the light beams scanned by the scanning unit. Big An image projection apparatus characterized by Kusuru.

In the above configuration, a first position at which the first light beam is focused and a first distance between the retina, and a second distance between the second light beam and the second position at which the second light beam is focused are respectively: The configuration may be smaller than the first distance and the second distance when it is assumed that the condensing powers in the third region and the fourth region are the same.

In the above configuration, the optical component may be a second mirror, and a curvature of the second mirror in the third region may be larger than a curvature of the second mirror in the fourth region.

In the above configuration, the optical component may be a diffraction grating, and a pitch of the diffraction grating in the third region may be larger than a pitch of the diffraction grating in the fourth region.

In the above-described configuration, the light collection power of the first mirror in the first region may be smaller than the light collection power of the first mirror in the second region.

In the above configuration, the first area and the second area may be located on both sides in the light beam incident direction with respect to a position corresponding to the center of the image in the first mirror. it can.

In the above configuration, the distance between the first region and the second region in the first mirror may be larger than the distance between the third region and the fourth region in the optical component.

In the above configuration, the optical corresponding to a pair of positions in the first mirror that is in a symmetrical relationship with respect to a line extending in a direction in which the light beam is incident through a position corresponding to the center of the image in the first mirror. The focused powers at a pair of locations in the component can be of substantially equal configuration.

The present invention generates an image light beam based on a light source unit for emitting a light beam, an image input unit for inputting image data, and the input image data, and controls emission of the image light beam from the light source unit. Control unit, a scanning mirror for scanning the image light beam, a reflection mirror for reflecting the image light beam scanned by the scanning mirror, and an image light beam reflected by the reflection mirror on the retina of the eyeball of the user A projection mirror, the surface of the projection mirror having a free-form surface, and the surface of the reflection mirror being an image projector having a free-form surface corresponding to a change in curvature of the free-form surface of the projection mirror.

In the above configuration, the free curved surface of the reflection mirror can be configured to include a concave surface and a convex surface.

In the above configuration, the free curved surface of the projection mirror has regions with different curvatures, and the image light rays reflected by the concave surface and the convex surface of the reflection mirror are respectively irradiated to the different regions of the projection mirror and reflected by the concave surface And the concave curved surface of the reflecting mirror so that the projected image light beam is irradiated to the area of the projection mirror whose curvature is smaller than the curvature of the area of the projection mirror to which the image light beam reflected by the convex curved surface is irradiated. A convex curved surface can be set.

The present invention generates an image light beam based on a light source unit for emitting a light beam, an image input unit for inputting image data, and the input image data, and controls emission of the image light beam from the light source unit. Control unit, a scanning mirror for scanning the image light beam, a reflection mirror for reflecting the image light beam scanned by the scanning mirror, and an image light beam reflected by the reflection mirror on the retina of the eyeball of the user A projection mirror, the surface of the projection mirror having a free-form surface, and the reflection mirror being an image projector including a reflective diffraction element corresponding to a change in curvature of the free-form surface of the projection mirror.

In the above configuration, the reflection type diffractive element can be configured to have a phase distribution with different phase pitches.

In the above configuration, the free curved surface of the projection mirror has regions of different curvatures, and the image light rays reflected by the wide region of the phase pitch and the region of the narrow phase pitch of the reflective diffractive element differ in the curvature of the projection mirror. The image light rays respectively irradiated to the area and reflected in the wide area of the phase pitch are smaller in curvature than the curvature of the area of the projection mirror to which the image light rays reflected in the narrow area of the phase pitch are irradiated. The phase pitch of the reflective diffraction element may be set so as to illuminate the area of the mirror.

The present invention generates an image light beam based on a light source unit for emitting a light beam, an image input unit for inputting image data, and the input image data, and controls emission of the image light beam from the light source unit. Control unit, a scanning mirror for scanning the image light beam, a transmission mirror for reflecting the image light beam scanned by the scanning mirror, and an image light beam reflected by the transmission mirror on the retina of the eyeball of the user A projection mirror, the surface of the projection mirror having a free-form surface, and the transmission mirror is an image projector including a transmission type diffractive element corresponding to a change in curvature of the free-form surface of the projection mirror.

In the above configuration, the transmission type diffractive element can be configured to have a phase distribution with different phase pitches.

In the above configuration, the free-form surface of the projection mirror has regions of different curvatures, and the image light rays transmitted by the region of wide phase pitch and the region of narrow phase pitch of the transmissive diffraction element differ in curvature of the projection mirror. The image rays respectively irradiated to the area and transmitted in the wide area of the phase pitch have the curvature smaller than the curvature of the area of the projection mirror to which the image light transmitted in the narrow area of the phase pitch is irradiated. The configuration may be such that the phase pitch of the transmissive diffraction element is set so as to irradiate the area of the mirror.

According to the present invention, the in-focus position can be set to an appropriate position.

FIG. 1 is a top view of the image projection apparatus according to the comparative example and the first embodiment. FIG. 2 is a view showing an optical path of a light beam in the image projector according to the comparative example. Fig.3 (a) is a figure which shows the optical path of the light ray in the image projector which concerns on Example 1, FIG.3 (b) is an enlarged view of reflective mirror vicinity of Fig.3 (a). FIG. 4A is a perspective view showing the unevenness on the surface of the reflection mirror in Example 1, and FIG. 4B is a view showing Z in the X direction of the reflection mirror. FIG. 5 is a diagram showing contour lines in the reflection mirror of the first embodiment. FIG. 6A is a view showing an optical path of a light beam in the image projection apparatus according to the second embodiment, and FIG. 6B is an enlarged view of the vicinity of the reflective diffraction element in FIG. 6A. FIG. 7 is a diagram showing equal phase lines in the reflective diffraction element of Example 2. FIG. FIG. 8A is a view showing an optical path of a light beam in the image projection apparatus according to the third embodiment, and FIG. 8B is an enlarged view of the vicinity of the transmissive diffraction element in FIG. 8A. FIG. 9 is a diagram showing equal phase lines in the transmission type diffraction element of Example 3.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a top view of the image projection apparatus according to the comparative example and the first embodiment. A traveling direction in the projection mirror 24 of a light beam incident on the projection mirror 24 is taken as an X direction, and a direction orthogonal to the X direction at the projection mirror 24 is taken as a Y direction. In the following example, the X direction is horizontal. As shown in FIG. 1, the image projection device is of the glasses type. The glasses have a temple 10 and a lens 20. A light source 12, a scanning mirror 14 and a reflecting mirror 18 are provided on the temple 10 of the glasses. The light source 12 emits, for example, laser light 34 of a single or a plurality of wavelengths. The scanning mirror 14 scans the laser beam 34 emitted from the light source 12 in a two-dimensional direction. The reflection mirror 18 reflects the scanned laser beam 34.

Image data is input to the image input unit 15 from a camera and / or a recording device. The control unit 16 controls the emission of the laser beam 34 from the light source 12 based on the input image data. That is, the image signal is converted by the light source 12 (light source unit) into a laser beam which is an image beam. The control unit 16 is, for example, a processor such as a CPU (Central Processing Unit). The control unit 16 may not be provided, for example, in the glasses, but may be provided in an external device (for example, a portable terminal), or may be provided in the temple 10 of the glasses.

The scanning mirror 14 two-dimensionally scans the laser beam 34 emitted from the light source 12 and uses it as projection light for projecting an image on the retina 26 of the eye 22 of the user (user). The scanning mirror 14 is, for example, a MEMS (Micro Electro Mechanical Systems) mirror, and scans laser light in two dimensions in the horizontal direction and the vertical direction. In the following example, although the direction which scans a laser beam is made into the X direction and the Y direction, you may scan a laser beam in directions other than a X direction and a Y direction.

The reflection mirror 18 reflects the laser beam 34 scanned by the scanning mirror 14 toward the lens 20. A projection mirror 24 is provided on the surface of the lens 20 on the eyeball 22 side of the user. The projection mirror 24 projects an image on the retina 26 by irradiating the retina 26 of the eyeball 22 with the laser beam 34 scanned by the scanning mirror 14 and reflected by the reflection mirror 18. That is, the user can recognize an image by the afterimage effect of the laser light projected onto the retina 26. The projection mirror 24 is designed such that the focal position of the laser beam 34 scanned by the scanning mirror 14 is the pupil 28 of the eye 22. The laser beam 34 is incident on the projection mirror 24 almost immediately (that is, approximately in the −X direction).

FIG. 2 is a view showing an optical path of a light beam in the image projector according to the comparative example. In FIG. 2, light beams L0 to L2 are light beams scanned in the horizontal direction by the scanning mirror 14, and are irradiated to the projection mirror 24 from the −X direction. A ray L0 is a ray corresponding to the center of the image, and rays L1 and L2 are rays corresponding to the edge of the image. The rays L0 to L2 are reflected at the regions R0 to R2 of the projection mirror 24, respectively. The reflected light rays L 0 to L 2 converge at the pupil 28 located at the center of the iris 29, pass through the lens 30, and reach the retina 26. Region R0 is a region that reflects light ray L0 corresponding to the center of the image. The region R1 is a region from the region R0 in the -X direction (the direction in which the light beams L0 to L2 are incident). The region R2 is a region in the + X direction from the region R0. For Maxwell viewing, rays L0 to L2 will intersect near the pupil 28. However, the in-focus positions F0 to F2 of the respective light beams L0 to L2 deviate from the retina 26.

In FIG. 2, the light beam L 0 reflected by the projection mirror 24 is incident on the lens 30 as substantially parallel light and is focused near the retina 26. The light beam L1 reflected by the projection mirror 24 enters the lens 30 as diffused light. For this reason, the light beam L 1 is focused farther than the retina 26. The light beam L2 reflected by the projection mirror 24 enters the lens 30 as convergent light. For this reason, the light beam L2 is focused closer to the retina 26. As described above, when the light beam L0 is focused near the retina 26, the in-focus position F1 is farther from the projection mirror 24 than the retina 26. This is the distance D1 between the in-focus position F1 and the retina 26. The in-focus position F2 is closer to the projection mirror 24 than the retina 26. The distance D2 between the in-focus position F2 and the retina 26 is obtained.

The reason that the in-focus positions F0 to F2 differ in this way is that the curvature of the regions R0 to R2 of the projection mirror 24 is X when focusing light rays L0 to L2 incident on the projection mirror 24 from the -X direction on the pupil 28. This is because they differ in direction and / or cause an optical path difference of the light beams L0 to L2. For example, the region R2 has a curvature larger than that of R1. That is, the region R2 has a larger condensing power than R1. Therefore, the in-focus position F2 is closer to the light source than F1. In addition, when the projection mirror 24 is arranged parallel to the face, the light path of the light ray L2 is longer than the light ray L1. Thus, the in-focus position F2 is closer to the light source than F1. As described above, in the comparative example, when the light beams L0 to L2 are focused in the vicinity of the pupil 28 for Maxwell vision, a region in which the in-focus position largely deviates from the retina 26 occurs in the image. The optical system in the Y direction is substantially symmetrical with respect to the X axis, and in the Y direction, the shift of the in-focus position as in the X direction is less likely to occur.

The first embodiment is an example in which the reflection mirror 18 is used as an optical component. Fig.3 (a) is a figure which shows the optical path of the light ray in the image projector which concerns on Example 1, FIG.3 (b) is an enlarged view of reflective mirror vicinity of Fig.3 (a). As shown in FIGS. 3A and 3B, light beams L0 to L2 applied to the regions R0 to R2 of the projection mirror 24 are reflected at the regions S0 to S2 in the reflection mirror 18, respectively. The reflection mirror 18 has a free-form surface. The other configuration is the same as that of Comparative Example 1, and the description thereof is omitted.

FIG. 4A is a perspective view showing the unevenness on the surface of the reflection mirror in Example 1, and FIG. 4B is a view showing the height Z in the X direction of the reflection mirror. The X direction and the Y direction are directions corresponding to the X direction and the Y direction in the projection mirror 24. The height at the reflection mirror 18 is in the Z direction. In FIG. 4A, the Z direction is shown by enlarging the unevenness of the surface of the reflection mirror 18. As shown in FIGS. 4A and 4B, in the area S0, the surface of the reflection mirror 18 is substantially flat, in the area S1 the surface of the reflection mirror 18 is concave, and in the area S2, the surface of the reflection mirror 18 is It is convex. As a result, the collected power is approximately 0 in the region S0, the collected power is positive in the region S1, and the collected power is negative in the region S2. Therefore, the in-focus position F0 of the light ray L0 does not change from the comparative example. The in-focus position F1 of the light beam L1 is closer to the light source as compared with FIG. 2 of the comparative example, and the in-focus position F2 of the light beam L2 is farther from the light source than in FIG. Thereby, the in-focus positions F0 to F2 are in the vicinity of the retina 26.

Let Z on the surface of the reflection mirror 18 be a free-form surface expressed by the following equation.
Z = Σa _ij × X ⁱ × Y ^j
The origin (X = 0, Y = 0) corresponds to the center of the image, for example, around the area S0. a _ij is a coefficient. In order to make the collected power in the X direction different, at least one of the coefficients a _{ij in which} i is an odd-numbered term is set to a finite value (other than 0). The collected power in the Y direction at the projection mirror 24 is symmetrical with respect to the X axis. Therefore, the coefficient a _{ij in} which j is an odd term is set to 0. For example, let the coefficients a ₃₀ and a ₁₂ be finite. Thereby, a free-form surface as shown in FIG. 4 can be realized. To further adjust the free-form surface of the reflecting mirror 18, the coefficients a ₁₀ and / or a ₂₀ may be a finite value. Furthermore, higher order coefficients may be finite values.

In order to focus the laser light 34 on the retina 26, the contours on the surface of the reflection mirror 18 were simulated. FIG. 5 is a diagram showing contour lines in the reflection mirror of the first embodiment. In FIG. 5, Z at center (X, Y) = (0, 0) is 0. The distance between contour lines is 11.6 μm. Z decreases in the + X direction, and increases in the -X direction. FIG. 5 is circular because it is simulated based on the retina. What cut out a part of the circle in FIG. 5 as a square corresponds to FIG. 4 (a).

In the first embodiment, the surface of the reflection mirror 18 is set to a free-form surface such as a flat surface, a concave surface, or a convex surface in accordance with the change in the curvature of the free-form surface of the projection mirror 24. A light beam reflected by the convex surface of the reflecting mirror 18 with large collected power is irradiated to a region where the curvature of the projection mirror 24 is large, and it is reflected by a concave surface of the reflecting mirror 18 with small collected power in the region where the curvature of the projection mirror 24 is small. Irradiate the light beam. Thereby, as shown in FIG. 3, the light beams L0 to L2 can be focused in the vicinity of the retina 26. For example, the optical system including the projection mirror 24 is designed with the reflection mirror 18 as a plane without considering the focus positions F0 to F2 of the light beams L0 to L2. Thereafter, the surface of the reflection mirror 18 is designed as a free-form surface without changing the design of the projection mirror 24. Thus, the in-focus positions F0 to F2 of the light beams L0 to L2 are adjusted. Since the condensing powers given by the reflection mirror 18 to the respective light beams L0 to L2 are weak, the in-focus positions F0 to F2 can be adjusted with almost no influence on the trajectories of the light beams L0 to L2. Therefore, the optical system can be designed easily.

FIG. 6A is a view showing an optical path of a light beam in the image projection apparatus according to the second embodiment, and FIG. 6B is an enlarged view of the vicinity of the reflective diffraction element in FIG. 6A. As shown in FIGS. 6 (a) and 6 (b), a reflective diffraction element 18a is used as an optical component. The other configuration is the same as that of the first embodiment, and the description is omitted.

In order to focus the laser beam 34 on the retina 26, the phase distribution in the diffractive element 18a was simulated. FIG. 7 is a diagram showing equal phase lines in the reflective diffraction element of Example 2. FIG. In FIG. 7, the spacing between the lines is 50 × 2π rad. The spacing of the equiphase lines corresponds to the pitch of the diffractive elements 18a. As in Example 2, even if the reflective diffraction element 18a is used, the condensing power of the region S0 is almost 0, the condensing power of the region S1 is positive, and the condensing power of the region S2 is negative. it can.

FIG. 8A is a view showing an optical path of a light beam in the image projection apparatus according to the third embodiment, and FIG. 8B is an enlarged view of the vicinity of the transmissive diffraction element in FIG. 8A. As shown in FIGS. 8 (a) and 8 (b), a transmissive diffraction element 18b is used as an optical component. The light beams L0 to L2 reflected by the scanning mirror 14 pass through the regions S0 to S2 of the diffractive element 18b, respectively. The other configuration is the same as that of the first embodiment, and the description is omitted.

In order to focus the laser beam 34 on the retina 26, the phase distribution in the diffractive element 18b was simulated. FIG. 9 is a diagram showing equal phase lines in the transmission type diffraction element of Example 3. In FIG. 9, the spacing between the lines is 7.5 × 2π rad. As in the third embodiment, even if the transmission type diffraction element 18b is used, the condensing power of the region S0 is substantially zero, the condensing power of the region S1 is positive, and the condensing power of the region S2 is negative. it can.

In Comparative Example 1 as shown in FIG. 2, the projection mirror 24 (first mirror) is disposed in front of the eye 22 of the user. The projection mirror 24 projects an image on the retina 26 by reflecting a light beam incident from the −X direction and irradiating the retina 26 of the eyeball 22. In such an arrangement, as described with reference to FIG. 2, it is difficult to set the in-focus positions F0 to F2 of the light beams L0 to L2 in the vicinity of the retina 26.

Therefore, according to the first to third embodiments, as shown in FIG. 3, FIG. 6, and FIG. 8, an optical component that reflects or transmits the light beam scanned by the scanning mirror 14 (scanning unit) 18a or a transmissive diffractive element 18b). The projection mirror 24 illuminates the light beams L0 to L2 reflected or transmitted by the optical component. Thus, the optical components are arranged.

The optical component is configured to focus light power in a region S1 (third region) that reflects or passes the light beam L1 irradiated to the region R1 (first region) among the light beams scanned by the scanning mirror 14 into a region R2 (second region) Is made larger than the condensing power in the region S2 (fourth region) which reflects or passes the light beam L2 (second light beam) irradiated to the.

Thereby, the in-focus position F1 of the light beam L1 approaches the projection mirror 24, and the in-focus position F2 of the light beam L2 moves away from the projection mirror 24. Therefore, the in-focus positions F0 to F2 of the light beams L0 to L2 can be made near the retina 26. Therefore, the in-focus positions F0 to F2 can be set as appropriate positions.

A distance D1 (first distance) between the position F1 (first position) where the light beam L1 is in focus and the retina 26 and a distance D2 between the position F2 (second position) where the light beam L2 is in focus and the retina 26 The second distance) is smaller than the distance D1 and the distance D2 when it is assumed that the condensing powers in the region S1 and the region S2 are the same, respectively. As a result, the in-focus positions F0 to F2 of the light beams L0 to L2 can be made near the retina 26.

As a method of setting the condensing power in the regions S1 and S2, as in the first embodiment, the optical component is a reflection mirror 18 (second mirror). The curvature of the reflection mirror 18 in the region S1 is made larger than the curvature of the reflection mirror 18 in the region S2. Thereby, the condensing power in area | region S1 can be made larger than the condensing power in area | region S2. In the curvature, the concave surface is positive as in the region S1 of FIGS. 4A and 4B, and the convex surface is negative as the region S2. Further, by using the reflection mirror 18 as an optical component, even when the light beams L0 to L2 include a plurality of wavelengths, it is possible to set the condensing power of the light beams L0 to L2 of each wavelength with a single curved surface.

That is, according to the first embodiment, as shown in FIG. 3A to FIG. 5, the free curved surface of the reflection mirror 18 includes a concave curved surface and a convex curved surface, and the free curved surface of the projection mirror 24 has a region with different curvatures. doing. The image rays reflected by the concave surface and the convex surface of the reflection mirror 18 are respectively irradiated to different regions of the projection mirror 24. The image ray reflected by the concave surface (area S1) is set to the area R1 of the projection mirror 24 whose curvature is smaller than the curvature of the area R2 of the projection mirror 24 to which the image ray reflected by the convex surface (area S2) is irradiated. The concave curved surface and the convex curved surface of the reflection mirror 18 are set so as to be irradiated. Thereby, the in-focus positions F0 to F2 can be set as appropriate positions.

As in Examples 2 and 3, the optical components may be

diffractive elements

18a and 18b. The pitch of the

diffraction elements

18a and 18b in the region S1 is made larger than the pitch of the

diffraction elements

18a and 18b in the region S2. Thereby, the condensing power in area | region S1 can be made larger than the condensing power in area | region S2. By using the

diffraction elements

18a and 18b as optical components, the condensing power can be set more accurately. The collected power of the

diffractive elements

18a and 18b is wavelength dependent. For this reason, it is preferable that the light beams L0 to L2 be light of a single wavelength. When the light beams L0 to L2 include light of a plurality of wavelengths, it is preferable to stack diffractive elements corresponding to the respective wavelengths.

That is, according to the second embodiment, as shown in FIG. 6A to FIG. 7, the reflection mirror includes the reflection type diffraction element 18 a corresponding to the change of the curvature of the free curved surface of the projection mirror 24. The reflective diffraction element 18a has a phase distribution with different phase pitches. The image rays reflected by the wide region S2 of the phase pitch of the reflection type diffraction element 18a and the narrow region S1 of the phase pitch are respectively irradiated to the regions R2 and R1 having different curvatures of the projection mirror 24. The phase pitch of the reflective diffraction element 18a is set so that the image light beam reflected by the region S2 is irradiated to the region R2 whose curvature is smaller than the curvature of the region R1 to which the image light beam reflected by the region S1 is irradiated. It is done. Thereby, the in-focus positions F0 to F2 can be set as appropriate positions.

Further, according to the third embodiment, as shown in FIG. 8A to FIG. 9, the transmission mirror includes the transmission type diffraction element 18 b corresponding to the change in curvature of the free curved surface of the projection mirror 24. The transmissive diffraction element 18 b has a phase distribution with different phase pitches. The image rays transmitted through the wide region S2 of the phase pitch of the transmission type diffraction element 18b and the narrow region S1 of the phase pitch are respectively irradiated to the regions R2 and R1 having different curvatures of the projection mirror 24. The image light beam transmitted in the region S2 is irradiated to the region R2 having a smaller curvature than the curvature of the region R1 of the projection mirror 24 to which the image light beam transmitted in the region S1 is irradiated. The phase pitch is set. Thereby, the in-focus positions F0 to F2 can be set as appropriate positions.

Although the example in which the curvature of the projection mirror 24 differs in the X direction has been described, the projection mirror 24 may be a diffractive element. In order to allow the light beams L0 to L2 to pass through the pupil 28, it is preferable that the focusing power of the projection mirror 24 in the region R1 is smaller than the focusing power of the projection mirror 24 in the region R2. Although the example of the half mirror with which the projection mirror 24 was provided in the lens 20 was demonstrated, the projection mirror 24 may be a total reflection mirror.

The regions R1 and R2 are located on both sides of the light beams L0 to L2 with respect to the position (region R0) corresponding to the center of the image in the projection mirror 24. Thus, when the regions R0 to R2 are positioned, in the comparative example 1, the shift from the focusing position F0 to the focus position F2 from the retina 26 becomes large. Therefore, it is preferable to make the condensing powers of the regions S0 to S2 different.

Furthermore, the distance between the region R1 and the region R2 in the projection mirror 24 is larger than the distance between the region S1 and the region S2 in the optical component. As described above, in the optical system in which the distance between the regions R1 and R2 is large, if it is attempted to focus the light beams L0 to L2 in the vicinity of the pupil 28, the condensing powers of the regions R1 and R2 will be largely different. In addition, the optical paths of the light beams L0 to L2 are largely different. Thereby, the in-focus positions F1 and F2 are largely deviated from the retina 26 as shown in FIG. Therefore, in such an optical system, it is preferable to use optical components having different condensing powers in the regions S1 and S2.

The optical system of the light beams L0 to L2 is substantially symmetrical with respect to the Y-axis direction. Therefore, the collected power at a pair of positions in the optical component corresponding to a pair of positions in the projection mirror 24 symmetrical to a line extending in the X direction through a position corresponding to the center of the image in the projection mirror 24 is substantially Is preferably equal. For example, in FIG. 5, the curvatures at positions symmetrical to the Y = 0 straight line (X axis) are the same. In FIGS. 7 and 9, the pitches of the diffractive elements symmetrical to the Y = 0 line are the same.

Although the glasses-type HMD has been described as an example of the image projector, an image projector other than the HMD may be used. Although an example in which the image is projected on the retina 26 of one eyeball 22 has been shown, the image may be projected on the retina 26 of both eyes 22. Although the scanning mirror 14 has been described as an example of the scanning unit, the scanning unit may be capable of scanning a light beam. For example, other components such as potassium tantalate niobate (KTN) crystal which is an electro-optical material may be used as a scanning unit. Although the laser beam is described as an example of the light beam, light other than the laser beam may be used. The condensing powers in the regions S1 and S2 of the optical component may be either positive or negative. Although the incident directions of the light beams L0 to L2 to the projection mirror 24 have been described taking the horizontal direction as an example, the light beams L0 to L2 may be incident from the vertical direction or the oblique direction.

As mentioned above, although the embodiment of the present invention has been described in detail, the present invention is not limited to such a specific embodiment, and various modifications may be made within the scope of the subject matter of the present invention described in the claims. Changes are possible.

DESCRIPTION OF SYMBOLS 10 crane 12 light source 14 scanning mirror 16 control part 18

reflection mirror

18a, 18b diffraction element 20 lens 22 eyeball 24 projection mirror 26 retina 28 pupil 29 iris 30 lens 34 laser beam

Claims

A scanning unit that scans a light beam emitted from a light source in a two-dimensional direction;
An optical component that reflects or transmits the light beam scanned by the scanning unit;
A first mirror disposed in front of a user's eye, and reflecting the light beam reflected or transmitted by the optical component onto the retina of the eye to project an image onto the retina;
Equipped with
The first mirror has a first area and a second area, and in the first mirror, the first area is located in a direction in which the light beam is incident from the second area,
The optical component is a part of the light beam scanned by the scanning unit in a third area that reflects or passes the first light beam irradiated to the first region among the light beams scanned by the scanning unit. An image projector characterized in that it is made larger than the condensing power in the fourth area which reflects or passes the second light beam irradiated to the second area.
The first position at which the first light beam is focused and the first distance between the retina, and the second distance between the second light beam at which the second light beam is focused and the retina,
The image projection apparatus according to claim 1, wherein the first distance and the second distance are smaller than the first distance when it is assumed that the condensing powers in the third region and the fourth region are the same.
The optical component is a second mirror,
The image projection apparatus according to claim 1, wherein a curvature of the second mirror in the third area is larger than a curvature of the second mirror in the fourth area.
The optical component is a diffraction grating,
3. The image projector according to claim 1, wherein a pitch of the diffraction grating in the third area is larger than a pitch of the diffraction grating in the fourth area.
The image projection apparatus according to any one of claims 1 to 4, wherein a condensing power of the first mirror in the first area is smaller than a condensing power of the first mirror in the second area.
The first area and the second area are located on both sides of the light incident direction with respect to a position corresponding to the center of the image in the first mirror. The image projector of any one of 5.
The distance between the first area and the second area in the first mirror is larger than the distance between the third area and the fourth area in the optical component. An image projector according to any one of the preceding claims.
A pair in the optical component corresponding to a pair of positions in the first mirror that are in a symmetrical relationship with respect to a line extending in a direction in which the light beam is incident through a position corresponding to the center of the image in the first mirror. The image projection apparatus according to any one of claims 1 to 7, characterized in that the condensing powers at the position of are substantially equal.
A light source unit that emits a light beam;
An image input unit for inputting image data;
A control unit that generates an image light beam based on the input image data and controls emission of the image light beam from the light source unit;
A scanning mirror for scanning the image beam;
A reflecting mirror that reflects the image light beam scanned by the scanning mirror;
A projection mirror that projects the image light beam reflected by the reflection mirror onto the retina of the user's eye;
Equipped with
The surface of the said projection mirror has a free-form surface, The surface of the said reflective mirror has the free-form surface corresponding to the curvature change of the free-form surface of the said projection mirror.
The image projection apparatus according to claim 9, wherein the free curved surface of the reflection mirror includes a concave curved surface and a convex curved surface.
The free-form surface of the projection mirror has regions of different curvature,
The image rays reflected by the concave surface and the convex surface of the reflection mirror are respectively irradiated to different regions of the projection mirror;
The image light beam reflected by the concave surface is reflected such that the image light beam reflected by the convex surface is emitted to the area of the projection mirror whose curvature is smaller than the curvature of the area of the projection mirror to be irradiated 11. The image projection apparatus according to claim 10, wherein concave and convex surfaces of the mirror are set.
A light source unit that emits a light beam;
An image input unit for inputting image data;
A control unit that generates an image light beam based on the input image data and controls emission of the image light beam from the light source unit;
A scanning mirror for scanning the image beam;
A reflecting mirror that reflects the image light beam scanned by the scanning mirror;
A projection mirror that projects the image light beam reflected by the reflection mirror onto the retina of the user's eye;
Equipped with
An image projector comprising: a surface of the projection mirror having a free-form surface; and the reflection mirror including a reflective diffractive element corresponding to a change in curvature of the free-form surface of the projection mirror.
The image projection apparatus according to claim 12, wherein the reflective diffraction element has a phase distribution with different phase pitches.
The free-form surface of the projection mirror has regions of different curvature,
The image light rays reflected by the wide area of the phase pitch and the narrow area of the phase pitch of the reflection type diffractive element are respectively irradiated to the areas of different curvatures of the projection mirror;
The image light beam reflected in the wide area of the phase pitch is irradiated to the area of the projection mirror whose curvature is smaller than the curvature of the area of the projection mirror to which the image light beam reflected in the narrow area of the phase pitch is irradiated. The image projection device according to claim 13, wherein the phase pitch of the reflection type diffraction element is set to
A light source unit that emits a light beam;
An image input unit for inputting image data;
A control unit that generates an image light beam based on the input image data and controls emission of the image light beam from the light source unit;
A scanning mirror for scanning the image beam;
A transmission mirror that reflects the image beam scanned by the scanning mirror;
A projection mirror that projects the image light beam reflected by the transmission mirror onto the retina of the user's eye;
Equipped with
An image projector comprising: a surface of the projection mirror having a free-form surface; and the transmission mirror including a transmission type diffractive element corresponding to a change in curvature of the free-form surface of the projection mirror.
The image projection apparatus according to claim 15, wherein the transmission type diffractive element has a phase distribution with different phase pitches.
The free-form surface of the projection mirror has regions of different curvature,
The image rays transmitted through the wide region of the phase pitch and the narrow region of the phase pitch of the transmissive diffraction element are respectively irradiated to the regions of different curvatures of the projection mirror;
The image light beam transmitted in the wide area of the phase pitch is irradiated on the area of the projection mirror whose curvature is smaller than the curvature of the area of the projection mirror to which the image light beam transmitted in the narrow area of the phase pitch is irradiated. The image projection apparatus according to claim 16, wherein a phase pitch of the transmission type diffractive element is set.