Image display device

Abstract

To provide an image display device capable of achieving both downsizing and a wider viewing angle.SOLUTION: An image display device comprises: a light source (11); an image generation element (20) converting light from the light source (11) into image light; a light guide element (10) guiding the image light to the pupil of an observer; and a light guide part (21) guiding the image light to the light guide element (10). A distance between an emission surface (13a) of the image generation element for emitting image light and an incidence surface (21a) of the light guide part for receiving the image light is longer than 0 mm and equal to or less than 5 mm.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image display device that allows an observer to observe an image. [Background technology]

[0002] Conventionally, an image display device having a light guide plate is known. FIG. 18 is a conceptual diagram of a light beam propagating in a light guide plate in a conventional image display device. A light beam from an image generating element is incident on a first deflection means 1, deflected, and then propagated by total reflection in a light guide plate 3. A part of the light beam incident on a second deflection means 2 is deflected and directed toward a viewer's pupil SP, and another part is reflected, propagated by total reflection in the light guide plate 3, and enters the second deflection means 2. With this configuration, a plurality of light beams are emitted from the second deflection means 2, and the area in which the viewer can observe the light beams is expanded. Patent Document 1 discloses a configuration in which a light guide plate is disposed between a MEMS (Micro Electro Mechanical Systems) and an optical system in order to reduce the size of an image display device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 10,969,675 Summary of the Invention [Problem to be solved by the invention]

[0004] However, although Patent Document 1 discloses that the image display device can be made smaller, it does not disclose the conditions for realizing a wider viewing angle. If the distance between the MEMS and the light guide plate is not appropriately set, the viewing angle becomes very narrow.

[0005] An object of the present invention is to provide an image display device that is both compact and has a wide viewing angle. [Means for solving the problem]

[0006] An image display device as one aspect of the present invention comprises a light source, an image generating element that converts light from the light source into image light, a light guiding element that guides the image light to an observer's pupil, and a light guiding section that guides the image light to the light guiding element, and is characterized in that the distance between an exit surface from which the image light of the image generating element is emitted and an entrance surface of the light guiding section on which the image light is incident is longer than 0 mm and equal to or less than 5 mm. Effect of the Invention

[0007] According to the present invention, it is possible to provide an image display device that is both compact and has a wide viewing angle. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating an example of an image display device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram of an optical path in the image display device according to the first embodiment. [Diagram 3] FIG. 1 is a configuration diagram of an image display device according to a first embodiment. [Figure 4] FIG. 1 is a diagram showing the structure of a MEMS. [Diagram 5] FIG. 2 is a configuration diagram of an incident deflection means. [Figure 6] FIG. 2 is a diagram illustrating the configuration of a light source. [Figure 7] FIG. 4 is a diagram showing the light distribution characteristics of a light-emitting unit. [Figure 8] FIG. 1 is an explanatory diagram of a diffraction propagation condition. [Figure 9] FIG. 1 is a diagram illustrating a diffraction propagation condition. [Figure 10] FIG. 1 is a diagram showing the structure of a MEMS. [Figure 11] FIG. 2 is a diagram showing an arrangement of wave plates. [Figure 12] 4 is a diagram showing the relationship between an incident deflection means and an incident light beam. FIG. [Figure 13] FIG. 11 is a configuration diagram of an image display device according to a second embodiment. [Figure 14] FIG. 11 is a configuration diagram of an image display device according to a third embodiment. [Figure 15] FIG. 11 is a configuration diagram of an image display device according to a fourth embodiment. [Figure 16] FIG. 4 is a diagram showing the incidence angle characteristics of an incidence deflection means. [Figure 17] FIG. 13 is a configuration diagram of an image display device according to a fifth embodiment. [Figure 18] FIG. 13 is a conceptual diagram of a light beam propagating within a conventional light guide plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to refer to the same components, and duplicated descriptions will be omitted.

[0010] 1 is a schematic diagram of an example of an image display device according to an embodiment of the present invention. The image display device of this embodiment includes a light guide plate (light guide element) 10, a frame 900, a first acquisition unit 910, a second acquisition unit 920, a control unit 930, and an image generating element (not shown). The image display device allows an observer 1000 to view a display image 1100 through the light guide plate 10.

[0011] The first acquisition means 910 is, for example, an imaging device such as a camera, and acquires at least one of position information and viewpoint information of the observer 1000. The position information of the observer 1000 is information on the position of at least a part of the user, for example, information on the position of the pupil SP of the observer 1000. The viewpoint information of the observer 1000 is information on the viewpoint or line of sight of the observer 1000, for example, information on the movement of the pupil SP of the user. The first acquisition means 910 can detect the amount of deviation of the position of the observer's pupil SP with respect to the image generating element by acquiring the position information of the user. The control means 930 can correct the deviation of the relative position between the image generating element and the pupil SP of the observer 1000 based on the information acquired by the first acquisition means 910.

[0012] The second acquisition means 920 is, for example, an imaging device such as a camera, and acquires external world information (peripheral information). The second acquisition means 920 can detect the brightness of the external world by acquiring the external world information. The control means 930 can display the display image 1100 with an appropriate brightness to the observer 1000 based on the information acquired by the second acquisition means 920. Note that the brightness of the display image 1100 can also be arbitrarily determined by the observer 1000 operating the control means 930, regardless of the information acquired by the second acquisition means 920.

[0013] The image generating element converts light from a light source into image light. The image generating element may be disposed for each eye, or may be disposed for one eye. When an image generating element is disposed for each eye, it is possible to provide parallax to the display image, so that the viewer 1000 can view the display image 1100 in stereoscopic view.

[0014] The control means 930 may be disposed outside the frame 900 or may be disposed inside the frame 900. When disposed outside the frame 900, the connection between the control means 930 and the frame 900 may be wired or wireless. EXAMPLES

[0015] Fig. 2 is a configuration diagram of the image display device of this embodiment. Fig. 3 is an explanatory diagram of the optical path in the image display device of this embodiment. The image display device of this embodiment has a light guide plate 10, a light source 11, a λ / 4 wavelength plate 12, an entrance deflection means (light guide section) 21, an exit deflection means 22, and a MEMS (Micro Electro Mechanical Systems) 20. In this embodiment, the entrance deflection means 21 and the exit deflection means 22 are coupled to the light guide plate 10.

[0016] The λ / 4 wave plate 12 is a wave plate that imparts a phase difference of λ / 4. The MEMS 20 includes a reflecting mirror 13 that reflects incident light, and an exterior (protective member) 14 for protecting the reflecting mirror 13, and is a two-dimensional raster-scan type scanning reflecting mirror in which the reflecting mirror 13 swings around the x-axis and y-axis with the center of the reflecting mirror 13 as the axis, as shown in FIG. 4. The light beam emitted from the light source 11 passes through the light guide plate 10, the incident deflection means 21, and the λ / 4 wave plate 12, and enters the MEMS 20. In this embodiment, the MEMS 20 is used as an example of an image generating element, but other elements may be used.

[0017] The light beam (image light) emitted from the MEMS 20 is deflected by the entrance deflection means 21 and propagates inside the light guide plate 10 by total reflection. The light beam incident on the light beam splitting deflection means 10a provided on the light guide plate 10 is deflected while being split in the x-axis direction and is guided to the exit deflection means 22. The light beam incident on the exit deflection means 22 is deflected while being split in the y-axis direction and is emitted to the pupil SP. Here, in this embodiment, the direction deflected by the entrance deflection means 21 (x direction) and the direction deflected by the light beam splitting deflection means 10a (y direction) are orthogonal to each other, but each means may deflect the light beam at a different angle as long as the light beam incident on the light guide plate 10 can be emitted to the pupil SP.

[0018] FIG. 5 is a configuration diagram of the incident deflection means 21. The incident deflection means 21 includes a diffraction element having a lattice structure P finer than the wavelength λ of the light beam emitted from the light source 11, as shown in FIG. 5(a) to FIG. 5(d), and has optical anisotropy due to polarization. In this embodiment, the incident deflection means 21 has a property (polarization selectivity) of transmitting P-polarized light and diffracting S-polarized light. In this embodiment, the light beam emitted from the light source 11 is P-polarized light, and is not diffracted by the incident deflection means 21, but is transmitted through the incident deflection means 21. The efficiency and diffraction angle for each diffraction order can be controlled by changing the shape, height, refractive index, etc. of the lattice structure, and may be determined according to the requirements required for the image display device. In this embodiment, the incident deflection means 21 is a diffractive optical element, but may be a holographic element as long as it has a deflection action of the light beam and anisotropy due to polarization.

[0019] The P polarized light transmitted through the incident deflection means 21 is reflected by the reflecting mirror 13 and enters the incident deflection means 21 again. Here, the phase of the P polarized light transmitted through the incident deflection means 21 is inverted by 90 degrees by the λ / 4 wave plate 12 arranged between the incident deflection means 21 and the MEMS 20 before it enters the incident deflection means 21 again, and it becomes S polarized light. The light beam that enters the incident deflection means 21 again as S polarized light is diffracted by the incident deflection means 21 and propagates within the light guide plate 10 by total reflection.

[0020] FIG. 6 is a configuration diagram of the light source 11. FIG. 7 is a diagram showing the light distribution characteristic of the light emitting unit 15. The light emitted from the light emitting unit 15 is linearly polarized light and has different divergence angles in the x-axis direction and the y-axis direction, so that the light beam cross section (FFP) of the xy cross section perpendicular to the z-axis direction of the light emitted from the light emitting unit 15 is elliptical. The light emitted from the light emitting unit 15 is collimated by a collimator lens 16 having the same focal length. Therefore, the light source 11 emits a collimated light beam 18 whose cross section has an elliptical shape with the x-axis direction as the minor axis, as shown in FIG. 6(c). Note that by using an anamorphic collimator lens system, the light source 11 can emit a collimated light beam whose cross section has an approximately circular shape.

[0021] Also, a λ / 2 wave plate 17 may be disposed behind the collimator lens 16 (the side opposite to the light emitting unit 15) to control the emitted polarization. In this embodiment, the light beam emitted from the light source 11 is a collimated light beam having a wavelength in the range of 520 to 540 nm from a semiconductor laser, but it may be a collimated light beam obtained by combining light beams from red, green, and blue semiconductor lasers. A photonics crystal laser or a light emitting diode may be used instead of the semiconductor laser.

[0022] The diffraction propagation conditions will be described below with reference to Fig. 8. Fig. 8 is an explanatory diagram of the diffraction propagation conditions.

[0023] In this embodiment, if the reflecting mirror 13 is tilted by angle ω when the light beam is incident on the reflecting mirror 13, the light beams (18-, 18+) reflected by the reflecting mirror 13 are tilted by angle 2ω (=θ) with respect to the collimated light beam 18. As shown in Fig. 8(b), the separated light beams are incident on the incident deflection means 21. The width φ' of the light beams of the full angle of view separated on the incident deflection means 21 is expressed by the following equation (1).

[0024] φ'=φ+2×L×tanθ (1) Here, φ is the diameter of the light beam incident on the reflecting mirror 13. L is the distance between the reflecting surface (exit surface) 13a from which the image light of the reflecting mirror 13 exits and the incident surface 21a on which the image light of the incident deflection means 21 enters. θ is the exit angle of the image light from the reflecting mirror 13. In this embodiment, the distance L is the distance (shortest length) between the center of the reflecting surface 13a and the incident surface 21a of the incident deflection means 21.

[0025] 8(b), it is assumed that the width InW of the incident deflection means 21 is equal to the width φ' of the light beam of the full angle of view separated on the incident deflection means 21. When a light beam having a diameter exceeding the diameter (effective diameter) m of the reflecting surface of the reflector 13 is incident on the reflector 13, the light beam in an area outside the area of ​​the effective diameter m is not guided correctly, so the effective diameter m of the reflector 13 becomes the diameter φ of the light beam incident on the reflector 13.

[0026] As described above, the light beam that is incident again on the incident deflection means 21 is diffracted and propagates inside the light guide plate 10 by total reflection, but when the diffracted light beam is incident again on the incident deflection means 21, it is diffracted again and is not propagated correctly.

[0027] Therefore, in this embodiment, in order to prevent the diffracted light beam from being incident on the incident deflection means 21 again, it is necessary to satisfy the following conditional expression (2).

[0028] D / InW≧0.25 (2) Here, InW is the length of the light guide plate 10 of the incident surface 21a in the direction in which the image light propagates (x-axis direction), and D is the propagation distance of the light beam (18-) at the negative angle of view in one total reflection.

[0029] When the length of the light guide plate 10 in the direction perpendicular to the incident surface 21a is d and the critical angle of the light guide plate 10 is θc, the propagation distance D is expressed by the following formula (3).

[0030] D = 2 × d × tan θc (3) Since the critical angle θc is determined by the refractive index nd of the light guide plate 10 at the d-line (wavelength 587.6 nm), formula (3) can be expressed by the following formula (4).

[0031] D = 2 × d × tan(asin(1 / nd)) (4) By substituting equation (4) into conditional equation (2), conditional equation (2) is expressed by the following conditional equation (5).

[0032] 2×d×tan(asin(1 / nd)) / InW≧0.25 (5) As described above, in this embodiment, it is assumed that the width InW of the incident deflection means 21 coincides with the width φ' of the light beam of the full angle of view separated on the incident deflection means 21. Therefore, using formula (1), conditional formula (5) can be modified to the following conditional formula (6). L≦(2×d×tan(asin(1 / nd))-0.25φ) / (0.5×tanθ) (6) By making the distance L satisfy the conditional expression (6), it is possible to realize an image display device that is both compact and has a wide viewing angle. Specifically, if the distance L is greater than 0 mm and equal to or less than 5 mm, the conditional expression (6) can be satisfied. Note that the distance L is preferably equal to or less than 4 mm. Furthermore, the distance L is more preferably equal to or less than 3 mm.

[0033] It is sufficient to further simplify condition (6) and satisfy the following condition (6a).

[0034] 0 <L / φ≦5 (6a) Although it is possible to propagate light beams over the entire field of view even when formula (5) is satisfied, a part of the diffracted light beams re-enters the incident deflection means 21 and is not guided correctly, as shown in Fig. 9(a). In order to propagate light beams efficiently, it is desirable to satisfy the following condition formula (7).

[0035] 2×d×tan(asin(1 / nd)) / InW≧0.5 (7) Moreover, in consideration of the uniformity within the pupil SP, it is further desirable to satisfy the following conditional expression (8).

[0036] 2×d×tan(asin(1 / nd)) / InW≧1.0 (8) As described above, it is desirable that the width InW of the incident deflection means 21 and the width φ' of the light beam of the full angle of view separated on the incident deflection means 21 are equal. However, as shown in Fig. 9(b), a part of the light beam of a certain angle of view re-enters the incident deflection means 21 and is not guided correctly, but it is possible for the light beam to propagate. In that case, it is desirable that the width InW of the incident deflection means 21, the width φ' of the light beam of the full angle of view separated on the incident deflection means 21, and the diameter φ of the light beam incident on the reflecting mirror 13 satisfy the following conditional formula (9).

[0037] φ' <InW+2×φ (9) Although it is possible to propagate light beams over the entire field of view even when formula (9) is satisfied, a part of the diffracted light beams re-enters the incident deflection means 21 and is not guided correctly, as shown in Fig. 9(a). In order to propagate light beams efficiently, it is desirable to satisfy the following condition formula (10).

[0038] φ'≦InW+φ (10) Moreover, in consideration of the uniformity within the pupil SP, it is further desirable to satisfy the following conditional expression (11).

[0039] φ'≦InW (11) The viewing angle of the image display device will be described below. Since the light beam propagates through the inside of the light guide plate 10 by total reflection while maintaining the angle, it is necessary to make the light beam incident on the entrance deflection means 21 at an angle equivalent to the viewing angle to be obtained at the pupil SP. As shown in formula (1), when the exit angle θ of the light reflected by the reflecting mirror 13 increases, the width φ' of the light beam of the full angle of view separated on the entrance deflection means 21 increases, making it difficult to satisfy the diffraction propagation condition. By shortening the distance L between the reflecting mirror 13 and the entrance deflection means 21, it is possible to suppress the increase in the width φ' of the light beam of the full angle of view separated on the entrance deflection means 21 even if the exit angle θ is increased, and the diffraction propagation condition can be satisfied at a wider angle. This makes it possible to widen the viewing angle of the image display device. In this embodiment, as shown in FIG. 2, the MEMS 20 is arranged to face the second surface 10c facing the first surface 10b of the light guide plate 10 into which the light beam emitted from the light source 11 is incident. Therefore, the light beam emitted from the light source 11 enters the light guide plate 10 from the first surface 10b, passes through the light guide plate 10, the incident deflection means 21, and the λ / 4 wavelength plate 12, and enters the MEMS 20. With this configuration, it is possible to shorten the distance L between the reflecting mirror 13 and the incident deflection means 21. In order to prevent light loss, an anti-reflection film is applied to the first surface 10b of the light guide plate 10 on which the light beam emitted from the light source 11 enters.

[0040] A more desirable configuration will now be described.

[0041] In order to reduce the distance L between the reflecting mirror 13 and the incident deflection means 21, it is desirable that the light beam emitted from the light source 11 is incident on the MEMS 20 so as to be perpendicular to the reflecting surface of the reflecting mirror 13 (including the case where it is substantially perpendicular (approximately perpendicular)). That is, it is desirable that the reflecting surface of the reflecting mirror 13 when not driven (when stationary, when not energized) is arranged so as to be approximately parallel to the incident surface 21a of the incident deflection means 21. Here, approximately parallel means that the parallelism of the two surfaces is within ±2°. That is, it is sufficient that the inclination angle of the reflecting surface of the reflecting mirror 13 when not driven with respect to the incident surface 21a of the incident deflection means 21 is within ±2°. Also, as shown in FIG. 10, since the reflecting surface of the reflecting mirror 13 when not driven is approximately parallel to the incident surface or substrate surface 19 of the exterior 14, the parallelism of the incident surface or substrate surface 19 of the exterior 14 with respect to the incident surface 21a of the incident deflection means 21 may be used.

[0042] Moreover, it is desirable that the light beam emitted from the light source 11 enters the incident deflection means 21 so as to be orthogonal (including the case where it is substantially orthogonal (approximately orthogonal)) to the incident surface 21b opposite to the incident surface 21a of the incident deflection means 21. Note that, in consideration of the transmittance characteristics of P-polarized light of the incident deflection means 21, this embodiment is configured so that the light beam emitted from the light source 11 enters the incident surface 21b of the incident deflection means 21 within a range of ±10° with respect to the normal to the incident surface 21b of the incident deflection means 21.

[0043] Furthermore, it is desirable that the thickness of the λ / 4 wave plate 12 is thin. The λ / 4 wave plate 12 may be a retardation plate made of quartz, or may be a film laminated to a substrate. When using a film laminated to a substrate, it is possible to shorten the distance L by using a substrate material with a higher refractive index, since the air-equivalent length can be shortened. Specifically, it is desirable to use a material with a refractive index of 1.5 or more.

[0044] 11(a), the λ / 4 wave plate 12 may be held by utilizing the exterior 14. By arranging the λ / 4 wave plate 12 adjacent to the opening of the exterior 14, it is possible for the λ / 4 wave plate 12 to also function as a cover glass and prevent foreign matter from entering the interior. Note that, as long as the λ / 4 wave plate 12 is arranged adjacent to the opening of the exterior 14, it may be adhered to the exterior 14 with an adhesive or may be held by a mechanical component such as a pressing spring.

[0045] 11(b), the λ / 4 wave plate 12 may be formed on the reflecting surface 13a of the reflecting mirror 13. By forming the λ / 4 wave plate 12 on the reflecting surface 13a, it is not necessary to dispose a separate optical element, and the distance L can be minimized. In this case, the λ / 4 wave plate 12 is configured as a wave plate on a film made of polycarbonate or olefin resin.

[0046] 6(c), the cross-sectional shape of the collimated light beam emitted from the light source 11 is elliptical. In this case, if the cross-sectional shape of the light beam incident on the incident deflection means 21 is also elliptical, it is desirable to make the propagation direction (x-axis direction) in which the light guide plate 10 propagates the image light coincide with the minor axis direction of the ellipse as shown in FIG. 12. This makes it possible to make the width φ' of the light beam of the full angle of view separated on the incident deflection means 21 smaller than that of a circular light beam, thereby enabling a wider field of view and a smaller width InW of the incident deflection means 21. EXAMPLES

[0047] This embodiment differs from the first embodiment in that the light beam emitted from the light source 11 is deflected once and then enters the light guide plate 10. In this embodiment, only the configurations different from the first embodiment will be described, and the description of the common configurations will be omitted.

[0048] 13 is a configuration diagram of the image display device of this embodiment. The image display device of this embodiment has a deflection element 31 in addition to the configuration of embodiment 1. In this embodiment, the deflection element 31 is a metal mirror, but it may be a dielectric mirror or a PBS (Polarizing Beam Splitter) as long as it can deflect light toward the light guide plate 10.

[0049] In this embodiment, the light beam emitted from the light source 11 is deflected by the deflection element 31 and then enters the light guide plate 10. In this embodiment, the light source 11 is rotated around the y-axis, so that the depth direction (z-direction) of the MEMS 20 can be shortened compared to the first embodiment.

[0050] 13(b), a light receiver 32 for monitoring information related to the light source 11 may be disposed on the rear surface of the deflection element 31. In this embodiment, the light receiver 32 senses the amount of light, but it may also sense the color. By disposing the light receiver 32 for monitoring information related to the light source 11 and performing feedback control, it is possible to reduce the variation of the light source 11 and improve the quality of the displayed image.

[0051] 13(c), it is also possible to ensure high reflectance by taking into consideration the reflectance characteristics of deflection element 31 and making the light beam emitted from light source 11 incident on deflection element 31 as S-polarized light. In that case, wave plate 33 may be disposed between deflection element 31 and light guide plate 10. The phase of the S-polarized light emitted from deflection element 31 is rotated by 90° by wave plate 33 and is incident on light guide plate 10 as P-polarized light. EXAMPLES

[0052] This embodiment differs from the first embodiment in that the light beam emitted from the light source 11 is deflected twice and then enters the light guide plate 10. In this embodiment, only the configurations different from the first embodiment will be described, and the description of the common configurations will be omitted.

[0053] 14 is a configuration diagram of the image display device of this embodiment. The image display device of this embodiment has deflection elements 34 and 35 in addition to the configuration of the first embodiment.

[0054] In this embodiment, the light beam emitted from the light source 11 is deflected twice by the deflection elements 34 and 35, and then enters the light guide plate 10. In this embodiment, by deflecting the light beam emitted from the light source 11 twice, the light source 11 can be accommodated within the frame 900, and the overall size of the device can be reduced.

[0055] 14(b), an element 36 having two reflecting surfaces may be provided instead of the deflection elements 34 and 35. In this case, by selecting a glass material with an appropriate refractive index, it is also possible to deflect the light by total reflection. EXAMPLES

[0056] This embodiment differs from the first embodiment in that the image light from the reflecting mirror 13 of the MEMS 20 is incident on the incident deflection means 21 at an angle with respect to the normal to the incident surface 21a of the incident deflection means 21. In this embodiment, only the configurations different from the first embodiment will be described, and a description of the common configurations will be omitted.

[0057] Fig. 15 is a configuration diagram of the image display device of this embodiment. Fig. 16 is a diagram showing the incident angle characteristics of the incident deflection means 21, and shows the diffraction efficiency with respect to the incident angle of the light beam incident on the incident deflection means 21.

[0058] As shown in FIG. 16, when the diffraction efficiency of the incident deflection means 21 is not maximum when the incident angle is 0°, the light can be propagated in the light guide plate 10 with high efficiency by making the light beam incident at the incident angle at which the diffraction efficiency is maximum. Incidentally, it is not necessary to make the light beam incident at the incident angle at which the diffraction efficiency is maximum strictly, and the light beam may be incident at an incident angle within ±5° of the incident angle at which the diffraction efficiency is maximum. In this case, the optical distance between the reflecting mirror 13 and the incident deflection means 21 is longer than when the image light is perpendicularly incident on the incident surface 21a of the incident deflection means 21. However, by arranging the reflecting mirror 13 so that the reflecting surface 13a of the reflecting mirror 13 when not driven is approximately parallel to the incident surface 21a of the incident deflection means 21, the increase in the optical distance can be suppressed by tilting the entire MEMS 20. Approximately parallel means that the parallelism of the two surfaces is within ±2°. In addition, since the reflecting surface 13a of the reflecting mirror 13 and the exit surface of the exterior 14 or the substrate surface 19 are approximately parallel when not driven, the parallelism of the exit surface of the exterior 14 or the substrate surface 19 with respect to the entrance surface 21a of the entrance deflection means 21 may also be used.

[0059] In addition, in this embodiment, image light is emitted from reflecting mirror 13 at an angle with respect to the normal to reflecting surface 13a of reflecting mirror 13, so even if the light has the same angle of view, the light incident on reflecting mirror 13 and the emitted image light do not match. That is, it is possible to realize a configuration in which the incident light does not pass through incident deflection means 21. If there is no need to pass through incident deflection means 21, there is no need to control polarization, and there is no need to place λ / 4 wave plate 12 between incident deflection means 21 and MEMS 20. EXAMPLES

[0060] This embodiment differs from the first embodiment in that a spatial light modulator (SLM) is used as an image generating element instead of a MEMS. In this embodiment, only the configuration different from the first embodiment will be described, and the description of the common configuration will be omitted.

[0061] 17 is a configuration diagram of an image display device of this embodiment. In this embodiment, a spatial phase modulator 37 such as an optical phased array (OPA) is used as an image generating element.

[0062] The spatial phase modulator 37 is a device that changes (modulates) the light beam emitted from the light source 11 by electrically controlling the spatial distribution (amplitude, phase, polarization, etc.) of the light beam. Specifically, it is possible to form image light for each angle of view by controlling the wavefront shape of the light beam incident on the spatial phase modulator 37 and changing the emission angle of the image light to be emitted. Note that, if the spatial phase modulator 37 is capable of controlling polarization, there is no need to place a λ / 4 wave plate between the light guide plate 10 and the spatial phase modulator 37.

[0063] Furthermore, as shown in FIG. 17(b), when the spatial phase modulator 37 is of a transmissive type, it is not necessary to make the light beam emitted from the light source 11 incident on the spatial phase modulator 37 from the side of the light guide plate 10, and the distance between the incident deflection means 21 and the spatial phase modulator 37 can be further shortened.

[0064] Various values ​​that can be used in each embodiment are summarized in the following Table 1. Note that n1 is the refractive index of air, and n2 is the refractive index nd of the light guide plate 10 at the d line.

[0065] [Table 1]

[0066] The disclosure of this embodiment includes the following configuration.

[0067] (Configuration 1) A light source; an image generating element that converts light from the light source into image light; a light guide element that guides the image light to a viewer's pupil; a light guiding section that guides the image light to the light guiding element, The image display device, characterized in that the distance between an exit surface of the image generating element from which the image light is emitted and an entrance surface of the light guiding section into which the image light is incident is longer than 0 mm and 5 mm or less. (Configuration 2) When the length of the light guide element of the incident surface in the direction in which the image light propagates is InW, the length of the light guide element in the direction perpendicular to the incident surface is d, and the refractive index of the light guide element at the d line is nd, 2×d×tan(asin(1 / nd)) / InW≧0.25 2. The image display device according to claim 1, wherein the following condition is satisfied: (Configuration 3) the image generating element is disposed to face a second surface of the light guide element, the second surface facing the first surface; 3. The image display device according to claim 1, wherein light from the light source is incident on the first surface, passes through the light-guiding element and the light-guiding section, and is converted into the image light by entering the image generating element, and the image light passes through the light-guiding section and is incident on the second surface. (Configuration 4) 4. The image display device according to configuration 3, wherein the light guide section includes a diffraction element having polarization selectivity. (Configuration 5) The image display device according to configuration 4, wherein the light beam emitted from the light source is incident on the light guiding section at an incident angle within ±10° with respect to the normal of a surface opposite to the incident surface of the light guiding section. (Configuration 6) The image display device according to configuration 4, wherein the image light is inclined with respect to a normal to the incident surface and is incident on the incident surface at an incident angle within ±5° with respect to a light ray having an incident angle at which the diffraction efficiency of the light guiding section is maximized. (Configuration 7) 4. The image display device according to configuration 3, wherein an anti-reflection film is formed on the first surface. (Configuration 8) 4. The image display device according to configuration 3, wherein a light beam emitted from the light source is deflected along an optical path and then enters the light guide element from the first surface. (Configuration 9) a λ / 4 wave plate disposed between the second surface and the image generating element; The image display device according to configuration 3, characterized in that a light beam from the light source is incident on the first surface, passes through the light-guiding element, the light-guiding section, and the λ / 4 wavelength plate, and is converted into the image light by being incident on the image generating element, and the image light is transmitted through the λ / 4 wavelength plate and the light-guiding section to be incident on the second surface. (Configuration 10) 10. The image display device according to any one of configurations 1 to 9, wherein the image generating element is a scanning reflector. (Configuration 11) the image generating element includes a reflecting mirror and a protective member that protects the reflecting mirror, 10. The image display device according to claim 9, wherein the λ / 4 wave plate is held by the protective member. (Configuration 12) The image generating element includes a reflector. 10. The image display device according to claim 9, wherein the λ / 4 wave plate is formed on the reflecting mirror. (Configuration 13) The image generating element includes a reflector. 13. The image display device according to any one of configurations 1 to 12, wherein the reflector is arranged such that an inclination angle of the reflecting surface of the reflector with respect to the incident surface when no current is applied is within 2°. (Configuration 14) When the diameter of the reflecting surface of the scanning reflecting mirror that reflects the light beam emitted from the light source is φ and the distance between the reflecting surface and the incident surface is L, 0 <L / φ≦5 11. The image display device according to configuration 10, which satisfies the following conditional expression: (Configuration 15) A cross-sectional shape of the light beam entering the light guiding portion is an ellipse, An image display device according to any one of configurations 1 to 14, characterized in that a minor axis direction of a light beam incident on the light guide section coincides with a direction in which the light guide element propagates the image light. (Configuration 16) 16. The image display device according to any one of configurations 1 to 15, wherein the distance between the exit surface and the entrance surface is 4 mm or less. (Configuration 17) 17. The image display device according to any one of configurations 1 to 16, wherein the distance between the exit surface and the entrance surface is 3 mm or less.

[0068] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0069] 10 Light guide plate (light guide optical element) 11 Light source 13a Reflective surface (output surface) 20 MEMS (image generating element) 21 Incident deflection means (light guiding section) 21a Incidence plane 37 Spatial phase modulator (image generating element)

Claims

1. A light source and an image generating element that converts light from the light source into image light; a light guide element that guides the image light to the pupil of an observer; a light guide portion that guides the image light to the light guide element, the image generating element is disposed to face a second surface of the light guiding element that faces the first surface, light from the light source is incident on the first surface, passes through the light guide element and the light guide section, and is converted into the image light by being incident on the image generating element, and the image light passes through the light guide section and is incident on the second surface; An image display device, characterized in that the distance between an exit surface of the image generating element from which the image light is emitted and an entrance surface of the light guiding section onto which the image light is incident is longer than 0 mm and 5 mm or less.

2. When the length of the light guide element on the incident surface in the direction in which the image light propagates is InW, the length of the light guide element in the direction perpendicular to the incident surface is d, and the refractive index of the light guide element at the d line is nd, 2×d×tan(asin(1 / nd)) / InW≧0.25 2. The image display device according to claim 1, wherein the following condition is satisfied:

3. 3. The image display device according to claim 1, wherein the light guide section includes a diffraction element having polarization selectivity.

4. 4. The image display device according to claim 3, wherein the light beam emitted from the light source is incident on the light guiding section at an incident angle of within ±10° with respect to a normal to a surface of the light guiding section opposite the incident surface.

5. 4. The image display device according to claim 3, wherein the image light is inclined with respect to the normal to the incident surface and is incident on the incident surface at an incident angle within ±5° of a light ray having an incident angle at which the diffraction efficiency of the light guiding section is maximized.

6. 3. The image display device according to claim 1, wherein an anti-reflection film is formed on the first surface.

7. 3. The image display device according to claim 1, wherein a light beam emitted from the light source is deflected along its optical path and then enters the light guide element from the first surface.

8. a λ / 4 wave plate disposed between the second surface and the image generating element; 3. The image display device according to claim 1, wherein a light beam from the light source is incident on the first surface, passes through the light-guiding element, the light-guiding section, and the λ / 4 wavelength plate, and is converted into the image light by being incident on the image generating element, and the image light passes through the λ / 4 wavelength plate and the light-guiding section to be incident on the second surface.

9. 3. The image display device according to claim 1, wherein the image generating element is a scanning reflecting mirror.

10. the image generating element includes a reflecting mirror and a protective member that protects the reflecting mirror; 9. The image display device according to claim 8, wherein the λ / 4 wave plate is held by the protective member.

11. the image generating element includes a reflecting mirror; 9. The image display device according to claim 8, wherein the λ / 4 wave plate is formed on the reflecting mirror.

12. the image generating element includes a reflecting mirror; 3. The image display device according to claim 1, wherein the reflecting mirror is disposed so that the inclination angle of the reflecting surface of the reflecting mirror with respect to the incident surface when the current is not applied is within 2 degrees.

13. When the diameter of the reflecting surface of the scanning reflecting mirror that reflects the light beam emitted from the light source is φ and the distance between the center of the reflecting surface and the incident surface is L, 0<L / φ≦5 10. The image display device according to claim 9, wherein the following condition is satisfied:

14. a cross-sectional shape of the light beam incident on the light guide portion is an ellipse; 3. The image display device according to claim 1, wherein a minor axis direction of a light beam incident on the light guide section coincides with a direction in which the image light is propagated through the light guide element.

15. 3. The image display device according to claim 1, wherein the distance between the exit surface and the entrance surface is 4 mm or less.

16. 3. The image display device according to claim 1, wherein the distance between the exit surface and the entrance surface is 3 mm or less.

Images