Image Projection Device

Abstract

Ensure sufficient clearance between the user's face. [Solution] An image projection device comprising: a light source; a control unit that generates image light rays based on image data and controls the emission of the image light rays from the light source; a scanning unit that scans the image light rays emitted from the light source in two dimensions; a light-guiding member formed from a glass material through which the multiple image light rays emitted from the scanning unit at different times pass, and having multiple reflective surfaces that reflect the multiple image light rays, including a reflective surface with positive focusing power, and that converges the multiple image light rays reflected by the multiple reflective surfaces at a first convergence point in the user's eye and then irradiates them onto the user's retina; a first optical member that converges the multiple image light rays emitted from the scanning unit at a second convergence point in front of the light-guiding member and then causes the multiple image light rays to enter the light-guiding member; and a second optical member that is positioned at the second convergence point and causes each of the multiple image light rays to enter a reflective surface with positive focusing power among the multiple reflective surfaces provided on the light-guiding member as diffused light.

Description

[Technical Field]

[0001] The present invention relates to an image projection device. [Background technology]

[0002] There is known an image projection device that projects an image by two-dimensionally scanning light rays emitted from a light source and irradiating the scanned light rays onto a user's retina using Maxwellian vision. Also, an image projection device using Maxwellian vision that can project high-quality images with reduced distortion and defocus has been proposed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 065245 Summary of the Invention [Problem to be solved by the invention]

[0004] When the image projection device disclosed in Patent Document 1 is attached to a frame that is worn on the user's face, such as an eyeglass frame, the clearance between the image projection device and the user's face tends to become small.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide an image projection device that can ensure sufficient clearance between the image projection device and the user's face. [Means for solving the problem]

[0006] The present invention provides an image projection device comprising: a light source; a control unit that generates image light rays based on image data and controls the emission of the image light rays from the light source; a scanning unit that scans the image light rays emitted from the light source two-dimensionally; a light-guiding member that is formed from a glass material through which the image light rays emitted from the scanning unit at different times pass, and has a plurality of reflective surfaces that reflect the image light rays, the plurality of reflective surfaces including a reflective surface with positive focusing power, and that converges the image light rays reflected by the plurality of reflective surfaces at a first convergence point in the user's eye and then irradiates the image light rays onto the user's retina; a first optical member that converges the image light rays emitted from the scanning unit at a second convergence point in front of the light-guiding member and then causes the image light rays to enter the light-guiding member; and a second optical member that is positioned at the second convergence point and causes each of the image light rays to enter the reflective surface with positive focusing power among the plurality of reflective surfaces provided on the light-guiding member as diffused light.

[0007] In the above configuration, the scanning unit and the first optical member can be attached near the temples of a frame that is worn on the user's face, and the light-guiding member can be attached near the rim of the frame and can have a shape that extends from in front of the user's eyes toward the temples.

[0008] In the above configuration, the light guide member may have an odd number of reflecting surfaces as the plurality of reflecting surfaces, and may be configured so that the plurality of image light rays that are reflected by the first optical member and travel obliquely forward are incident thereon.

[0009] In the above configuration, the remaining reflecting surfaces of the plurality of reflecting surfaces other than the reflecting surface having the positive light-collecting power may be configured as substantially flat surfaces.

[0010] In the above configuration, the remaining reflecting surfaces may be configured to be approximately parallel to each other.

[0011] In the above configuration, the light-guiding member has a main body portion through which the multiple image light rays pass after being repeatedly reflected on the multiple reflecting surfaces and irradiated onto the user's retina, and a cover portion that covers the reflecting surface having positive focusing power and has a refractive index approximately the same as that of the main body portion, wherein an exit surface through which the multiple image light rays reflected on the reflecting surface having positive focusing power exit the main body portion and a surface of the cover portion opposite to the exit surface of the main body with respect to the reflecting surface having positive focusing power are located in front of the user's eyes, the multiple reflecting surfaces are half mirrors, and the exit surface of the main body portion and the opposite surface of the cover portion are flatter than the reflecting surface having positive focusing power.

[0012] In the above configuration, the light exit surface of the main body and the opposite surface of the cover may be configured to be substantially parallel to each other and substantially flat.

[0013] In the above configuration, the opposite surface of the cover portion may be configured to be a curved surface that can correct the user's vision.

[0014] In the above configuration, the magnitude of the convergence angle at which the plurality of image light rays converge to the first convergence point may be equal to or greater than the magnitude of the scanning angle of the plurality of image light rays by the scanning unit.

[0015] In the above configuration, the optical system may be configured to include a housing attached to the frame and containing the scanning unit, the first optical member, and the second optical member therein, and most of the light-guiding member is not located within the housing.

[0016] The present invention provides a light source, a control unit that generates image light rays based on image data and controls emission of the image light rays from the light source, a scanning unit that two-dimensionally scans the image light rays emitted from the light source, and a plurality of reflective surfaces formed of a glass material through which the plurality of image light rays emitted from the scanning unit at different times pass and that reflect the plurality of image light rays, the plurality of reflective surfaces including a reflective surface having a positive light-collecting power, and the plurality of image light rays reflected by the reflective surface having the positive light-collecting power that reflects the plurality of image light rays last among the plurality of reflective surfaces. and a light guiding member that converges a plurality of image light rays at a convergence point in the user's eye and then irradiates the plurality of image light rays onto the user's retina, wherein some of the plurality of image light rays pass through the reflective surface having positive focusing power, then re-enter and pass through the opposite side of the reflective surface having positive focusing power, are reflected by the reflective surface having positive focusing power, and are irradiated onto the user's retina, and the remaining image light rays do not pass through the reflective surface having positive focusing power, but are reflected by the reflective surface having positive focusing power, and are irradiated onto the user's retina.

[0017] In the above configuration, the plurality of image light rays may be configured to be reflected by the plurality of reflecting surfaces the same number of times and then irradiated onto the retinas of the user. [Effects of the Invention]

[0018] According to the present invention, it is possible to ensure sufficient clearance between the user's face and the headset. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1(a) is a diagram showing an optical system according to Comparative Example 1, and FIG. 1(b) shows the results of a simulation evaluating laser light irradiated onto a projection surface in the optical system of FIG. 1(a). [Figure 2] 2(a) and 2(b) show the results of a simulation evaluating the laser light irradiated onto the projection surface when the focal length of the lens placed at the convergence point is changed. [Figure 3]FIG. 3(a) is a diagram showing an optical system according to Comparative Example 2, and FIG. 3(b) shows the results of a simulation evaluating laser light irradiated onto a projection surface in the optical system of FIG. 3(a). [Figure 4] FIG. 4 is a diagram showing a state in which the optical system according to Comparative Example 2 is attached to an eyeglass-type frame. [Figure 5] FIG. 5(a) is a diagram showing an optical system according to Comparative Example 3, and FIG. 5(b) shows the results of a simulation evaluating laser light irradiated onto a projection surface in the optical system of FIG. 5(a). [Figure 6] Figure 6(a) is a diagram (part 1) showing an optical system in which the angle of incidence of laser light to the scanning unit is changed, and Figure 6(b) shows the simulation results evaluating the laser light irradiated onto the projection surface in the optical system of Figure 6(a). [Figure 7] Figure 7(a) is a diagram (part 2) showing an optical system in which the angle of incidence of the laser light to the scanning unit is changed, and Figure 7(b) shows the simulation results evaluating the laser light irradiated onto the projection surface in the optical system of Figure 7(a). [Figure 8] FIG. 8 is a diagram illustrating an image projection device according to the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of dimensions of the image projection device according to the first embodiment. [Figure 10] FIG. 10(a) is a diagram (part 1) showing the optical system for which the simulation was performed, and FIG. 10(b) shows the simulation results evaluating the laser light irradiated onto the projection surface in the optical system of FIG. 10(a). [Figure 11] FIG. 11(a) is a diagram (part 2) showing the optical system for which the simulation was performed, and FIG. 11(b) shows the simulation results evaluating the laser light irradiated onto the projection surface in the optical system of FIG. 11(a). [Figure 12] FIG. 12 is a diagram illustrating a state in which the image projection device according to the first embodiment is attached to an eyeglass frame. [Figure 13] FIG. 13 is a diagram illustrating an image projection device according to the second embodiment. [Figure 14]FIG. 14 is a diagram illustrating a case where a user views the outside world through a light-guiding member in the second embodiment. [Figure 15] FIG. 15 is a diagram illustrating an image projection device according to the third embodiment. [Figure 16] FIG. 16 is a diagram showing the relationship between the reflectance Rc and the ratio of the amount of light Pcr / Pct. [Figure 17] FIG. 17(a) is a diagram showing the relationship between reflectance Rc and the light amount ratio Pcr / Pi, and FIG. 17(b) is a diagram showing the relationship between reflectance Rc and transmittance Tar. DETAILED DESCRIPTION OF THE INVENTION

[0020] First, a comparative example of an optical system used in an image projection device will be described.

[0021] [Comparative Example 1] FIG. 1A is a diagram showing an optical system 500 according to Comparative Example 1. As shown in FIG. 1A, the optical system 500 of Comparative Example 1 includes a light source 110, a scanning unit 112, a lens 114, a reflecting mirror 116, a reflecting mirror 120, a projection mirror 122, and a lens 124. The light source 110 emits laser light 140. The lens 114 converts the laser light 140 emitted by the light source 110 from diffused light to focused light. The reflecting mirror 116 is a flat mirror that reflects the laser light 140 that has passed through the lens 114 toward the scanning unit 112. The scanning unit 112 scans the incident laser light 140 two-dimensionally. The multiple laser light beams 140 scanned two-dimensionally by the scanning unit 112 and emitted from the scanning unit 112 at different times are incident on the reflecting mirror 120. The reflecting mirror 120 is a concave mirror having a curved reflective surface.

[0022] Each of the scanned laser beams 140 is incident on the reflecting mirror 120 as diffused light, and is converted from diffused light into approximately parallel light by the reflecting mirror 120. The scanned laser beams 140 are reflected by the reflecting mirror 120 and converge at a convergence point 160 in front of the projection mirror 122. A lens 124 is disposed at the convergence point 160. Each of the scanned laser beams 140 is converted from approximately parallel light into converging light by the lens 124, and after being converged in front of the projection mirror 122, becomes diffused light and is incident on the projection mirror 122. The projection mirror 122 is a concave mirror having a curved reflective surface, and has approximately the same shape as the reflecting mirror 120 and approximately the same radius of curvature as the reflecting mirror 120.

[0023] Each of the plurality of laser beams 140 is converted from divergent light into approximately parallel light by the projection mirror 122. The plurality of laser beams 140 reflected by the projection mirror 122 converge at a convergence point 162 and then irradiate a projection surface 164.

[0024] When the optical system 500 is used in an image projection device, the convergence point 162 is located inside the user's eye (for example, near the pupil), and the laser light 140 is converted from approximately parallel light into convergent light by the crystalline lens and focused near the retina.

[0025] The scanning angle of the laser beam 140 by the scanning unit 112 is approximately the same as the convergence angle at which the multiple laser beams 140 converge at the convergence point 162. Furthermore, the optical path length of the laser beam 140 between the scanning unit 112 and the reflecting mirror 120 is approximately the same as the optical path length between the projection mirror 122 and the convergence point 162, and the optical path length between the reflecting mirror 120 and the convergence point 160 is approximately the same as the optical path length between the convergence point 160 and the projection mirror 122. Therefore, the scanning unit 112, the convergence point 160, and the convergence point 162 have a conjugate relationship of approximately equal magnification.

[0026] Fig. 1(b) shows the results of a simulation evaluating the laser beams 140 irradiated onto the projection surface 164 in the optical system 500 of Fig. 1(a). The simulation was performed on the assumption that the multiple laser beams 140 emitted from the scanning unit 112 each had a substantially circular shape and were distributed substantially uniformly in a substantially rectangular shape overall (the same applies to similar simulations below). As shown in Fig. 1(b), the scanning unit 112 and the convergence point 162 have a conjugate relationship of approximately equal magnification, so the multiple laser beams 140 on the projection surface 164 each had a substantially circular shape and were distributed substantially uniformly in a substantially rectangular shape overall.

[0027] Here, the reason for placing the lens 124 at the convergence point 160 will be explained. The lens 124 converts the laser light 140 from approximately parallel light to convergent light. The laser light 140 converted into convergent light by the lens 124 is converged in front of the projection mirror 122, and then becomes diffused light and enters the projection mirror 122. The projection mirror 122 has a positive focusing power that converges the multiple laser light beams 140 at the convergence point 162. Therefore, by placing the lens 124, whose focal length is set to an appropriate size, at the convergence point 160 and setting the NA (numerical aperture) when the laser light 140 enters the projection mirror 122 to an appropriate size, the laser light 140 reflected by the projection mirror 122 can be made into approximately parallel light.

[0028] 2(a) and 2(b) show simulation results evaluating the laser beams 140 irradiated onto the projection surface 164 when the focal length of the lens 124 disposed at the convergence point 160 is changed. FIG. 2(a) shows the simulation results when the focal length of the lens 124 is inappropriate, and FIG. 2(b) shows the simulation results when the focal length is appropriate. As shown in FIG. 2(a), when the focal length of the lens 124 is inappropriate, the sizes of the multiple laser beams 140 on the projection surface 164 vary. This indicates that when the focal length of the lens 124 is inappropriate, the multiple laser beams 140 reflected by the projection mirror 122 include laser beams 140 that are not substantially parallel. On the other hand, as shown in FIG. 2(b), when the focal length of the lens 124 is appropriate, the sizes of the multiple laser beams 140 on the projection surface 164 are substantially uniform. From this, it can be seen that when the focal length of the lens 124 is appropriate, all of the plurality of laser beams 140 reflected by the projection mirror 122 become substantially parallel beams.

[0029] In this way, by disposing the lens 124 that converts the laser beams 140 from substantially parallel beams to focused beams at the convergence point 160 and by appropriately adjusting the focal length of the lens 124 to an appropriate value to set the NA when the laser beams 140 are incident on the projection mirror 122, the multiple laser beams 140 reflected by the projection mirror 122 can be converted into substantially parallel beams. As a result, when the optical system 500 is used in an image projection device, the multiple laser beams 140 can be converted from substantially parallel beams to focused beams by the crystalline lens and focused near the retina, thereby providing a high-quality image to the user. Furthermore, since the convergence point 160 is the point where the multiple laser beams 140 converge, by disposing the lens 124 at the convergence point 160, it is possible to easily adjust the degree of convergence of the multiple laser beams 140 to an appropriate level.

[0030] Comparative Example 2 Here, it is desirable to enlarge the shape of the projection mirror placed in front of the user's eye in order to ensure a wide viewing angle of the image projected onto the user's retina. FIG. 3(a) is a diagram showing an optical system 600 according to Comparative Example 2. As shown in FIG. 3(a), the optical system 600 of Comparative Example 2 is provided with a projection mirror 122a having a larger radius of curvature than the reflecting mirror 120 instead of the projection mirror 122. As a result, the optical path length of the laser light 140 between the scanning unit 112 and the reflecting mirror 120 is different from the optical path length of the laser light 140 between the projection mirror 122a and the convergence point 162. The optical path length of the laser light 140 between the reflecting mirror 120 and the convergence point 160 is different from the optical path length of the laser light 140 between the convergence point 160 and the projection mirror 122a. On the other hand, the ratio of the optical path length of the laser light 140 between the reflecting mirror 120 and the convergence point 160 to the optical path length of the laser light 140 between the scanning unit 112 and the reflecting mirror 120 is approximately the same as the ratio of the optical path length of the laser light 140 between the convergence point 160 and the projection mirror 122a to the optical path length of the laser light 140 between the projection mirror 122a and the convergence point 162. Therefore, the optical system 600 has a similar layout at approximately the same magnification, and the scanning angle of the laser light 140 by the scanning unit 112 is approximately the same as the convergence angle at which the multiple laser light beams 140 converge at the convergence point 162.

[0031] The homothetic ratio of the optical system 600 may be determined by the distance between the projection mirror 122a and the user's eyes, the shape of the user's face, and / or the space on the sides of the user's face.

[0032] Fig. 3(b) shows the results of a simulation evaluating the laser beams 140 irradiated onto the projection surface 164 in the optical system 600 of Fig. 3(a). As shown in Fig. 3(b), since the optical system 600 has a similar layout at approximately the same magnification, the multiple laser beams 140 on the projection surface 164 each have an approximately circular shape and are distributed approximately uniformly in an approximately rectangular shape overall.

[0033] When the optical system 600 according to Comparative Example 2 is used in an image projection device, the optical system 600 may be attached to an eyeglass frame. FIG. 4 is a diagram showing the optical system 600 according to Comparative Example 2 attached to an eyeglass frame 190. Note that in FIG. 4, the path of the laser light 140 emitted by the light source 110 until it enters the scanning unit 112 is different from that shown in FIG. 3( a). As shown in FIG. 4, the projection mirror 122a is disposed in front of the user's eyes and is therefore disposed near the rim 194 of the eyeglass frame 190. Therefore, the reflection mirror 120 and the lens 124 are disposed near the user's face, and the laser light 140 passes close to the user's face. Furthermore, the reflection mirror 120, the projection mirror 122a, the lens 124, and the like are housed in a housing 196 to protect them and the laser light 140, and the housing 196 is attached to the temples 192 and rim 194 of the eyeglass frame 190. Because the reflecting mirror 120 and the lens 124 are disposed close to the user's face, the clearance between the housing 196 and the user's face is reduced. For example, the distance between the eye 70 and the housing 196 is shortened, which may cause the housing 196 to interfere with the eyelashes and reduce the quality of the image projected onto the retina 72. Furthermore, because the clearance between the housing 196 and the user's face is reduced, the housing 196 may interfere with the user's face depending on the shape of the user's face. Furthermore, the front-to-rear dimension of the housing 196 no longer fits into the clearance between a typical eyeglass frame and the face, necessitating a design that protrudes forward.

[0034] Comparative Example 3 Next, an optical system 700 according to Comparative Example 3 will be described, which has a larger viewing angle of the image than the optical system 600 according to Comparative Example 2. Fig. 5(a) is a diagram showing the optical system 700 according to Comparative Example 3. As shown in Fig. 5(a), in the optical system 700 according to Comparative Example 3, the position of the convergence point 162 is closer to the projection mirror 122a than in the optical system 600 according to Comparative Example 2, in order to increase the viewing angle of the image.

[0035] In the optical system 700 of Comparative Example 3, the position of the convergence point 162 is closer to the projection mirror 122a than in the optical system 600 of Comparative Example 2, and therefore, as is clear from Fig. 4, the clearance between the housing 196 and the user's face becomes even smaller. This makes it even more likely that the housing 196 will interfere with the eyelashes, resulting in a deterioration in image quality, or that the housing 196 will interfere with the user's face.

[0036] 5(b) shows the results of a simulation evaluating the laser beams 140 irradiated onto the projection surface 164 in the optical system 700 of FIG. 5(a). As shown in FIG. 5(b), the overall shape of the multiple laser beams 140 on the projection surface 164 is approximately trapezoidal, resulting in trapezoidal distortion. The trapezoidal distortion is thought to have occurred because the convergence point 162 is moved closer to the projection mirror 122a, which deviates from the approximately same-size similar layout. In other words, the optical power received from the projection mirror 122a when the laser beams 140 are obliquely incident on the projection mirror 122a and reflected by the projection mirror 122a cannot be canceled out by the optical power received from the reflection mirror 120 when the laser beams 140 are obliquely reflected by the reflection mirror 120, resulting in trapezoidal distortion.

[0037] To eliminate the trapezoidal distortion shown in Figure 5(b), one method is to process the image to be projected itself in advance to create an opposite trapezoidal distortion, and then cancel out the distortion created in advance and the distortion created by the optical system 700, thereby suppressing the trapezoidal distortion.However, there is also a method of suppressing the trapezoidal distortion by adjusting the angle of incidence of the laser light 140 on the scanning unit 112.

[0038] 6(a) and 7(a) are diagrams showing optical systems 710 and 720 in which the angle of incidence of laser light 140 on the scanning unit 112 is changed. As shown in Fig. 6(a), in the optical system 710, the laser light 140 is obliquely incident on the scanning unit 112 from the opposite side of the reflecting mirror 120 to the projection mirror 122a. As shown in Fig. 7(a), in the optical system 720, the laser light 140 is obliquely incident on the scanning unit 112 from the same side of the reflecting mirror 120 as the projection mirror 122a.

[0039] 6(b) and 7(b) show simulation results evaluating the laser beam 140 irradiated onto the projection surface 164 in the optical systems 710 and 720 of FIG. 6(a) and 7(a). As shown in FIG. 6(b), the trapezoidal distortion in the optical system 710 was worse than the simulation results for the optical system 700 shown in FIG. 5(b). The reason for the worsening trapezoidal distortion in the optical system 710 is believed to be as follows: In the optical system 710, the direction in which the laser beam 140 travels toward the scanning unit 112 is substantially the same as the direction in which the laser beam 140 reflected by the reflecting mirror 120 travels toward the projection mirror 122a. Therefore, the trapezoidal distortion caused by the laser beam 140 being incident on the projection mirror 122a from an oblique direction is combined with the trapezoidal distortion caused by the laser beam 140 being incident on the scanning unit 112 from substantially the same oblique direction, resulting in the worsening trapezoidal distortion.

[0040] On the other hand, as shown in Fig. 7(b), the trapezoidal distortion in the optical system 720 was improved compared to the simulation result of the optical system 700 shown in Fig. 5(b). The reason why the trapezoidal distortion was improved in the optical system 720 is considered to be as follows: In the optical system 720, the direction in which the laser light 140 travels toward the scanning unit 112 and the direction in which the laser light 140 reflected by the reflecting mirror 120 travels toward the projection mirror 122a are different directions (intersecting directions). For this reason, the trapezoidal distortion caused by the laser light 140 being incident on the projection mirror 122a from an oblique direction is weakened by the trapezoidal distortion caused by the laser light 140 being incident on the scanning unit 112 from a different oblique direction, and therefore the trapezoidal distortion is considered to have been improved.

[0041] In this way, by making the laser light 140 incident on the scanning unit 112 from a direction different from the direction in which the laser light 140 is reflected by the reflecting mirror 120 and travels toward the projection mirror 122a, it is possible to improve the trapezoidal distortion.

[0042] As shown in Figure 4, when the optical systems of Comparative Examples 2 and 3 are used in an image projection device, it is difficult to ensure sufficient clearance between the image projection device and the user's face. Furthermore, the image projection device also protrudes forward, which requires a dedicated frame and compromises the design. Therefore, an example of an image projection device that can ensure sufficient clearance between the user's face and the image projection device while reducing the forward protrusion of the image projection device is shown below. [Example]

[0043] FIG. 8 is a diagram illustrating an image projection device 100 according to a first embodiment. As shown in FIG. 8, the image projection device 100 includes a light source 10, a scanning unit 12, a lens 14, a reflecting mirror 16, a reflecting mirror 20, a lens 24, a light-guiding member 30, a control unit 50, and an image input unit 52. The image input unit 52 receives image data from a camera and / or a recording device (not shown). The control unit 50 controls the emission of laser light 40 from the light source 10 based on the input image data. Therefore, the image data is converted by the light source 10 into the laser light 40, which is an image beam. The control unit 50 also controls the driving of the scanning unit 12.

[0044] The light source 10 emits visible laser light, for example, red laser light (wavelength: approximately 610 nm to 660 nm), green laser light (wavelength: approximately 515 nm to 540 nm), and blue laser light (wavelength: approximately 440 nm to 480 nm), under the control of the control unit 50. An example of the light source 10 that emits red, green, and blue laser light is a light source in which RGB (red, green, and blue) laser diode chips and a three-color combining device are integrated. Note that the light source 10 may also emit laser light of a single wavelength.

[0045] The control unit 50 is a processor such as a CPU (Central Processing Unit). If a camera is installed at an appropriate position facing the user's line of sight, an image captured by the camera in the line of sight direction can be projected onto the retina 72. It is also possible to project an image input from a recording device or the like, or to superimpose a camera image and an image from a recording device or the like by the control unit 50, thereby projecting a so-called augmented reality (AR) image.

[0046] The laser light 40 emitted by the light source 10 passes through the lens 14. The lens 14 is a condenser lens that converts the laser light 40 from diffused light to focused light. The laser light 40 that has passed through the lens 14 is reflected by the reflecting mirror 16 toward the scanning unit 12 and enters the scanning unit 12 in the form of focused light. The reflecting mirror 16 is a flat mirror. The lens 14 is provided between the light source 10 and the scanning unit 12 to convert the laser light 40 reflected by the reflecting mirror 20 into approximately parallel light.

[0047] The scanning unit 12 (scanner) scans the incident laser beam 40 in two dimensions, horizontally and vertically. The scanning unit 12 is, for example, a scanning mirror such as a MEMS (Micro Electro Mechanical System) mirror. The scanning unit 12 may be made of other materials, such as potassium tantalate niobate (KTN). The multiple laser beams 40 scanned in two dimensions by the scanning unit 12 and emitted from the scanning unit 12 at different times are incident on the reflecting mirror 20. Each of the multiple laser beams 40 is focused in front of the reflecting mirror 20, then becomes diffused light, and then enters the reflecting mirror 20. The reflecting mirror 20 is a concave mirror having a reflective surface formed of a curved surface such as a free-form surface, and has positive focusing power. Therefore, each of the multiple laser beams 40 is converted from diffused light into approximately parallel light by being reflected by the reflecting mirror 20.

[0048] The plurality of laser beams 40 reflected by the reflecting mirror 20 converge at a convergence point 60 in front of the light-guiding member 30. A lens 24 is provided at the convergence point 60. The lens 24 is a condenser lens that converts each of the plurality of laser beams 40 from approximately parallel beams into focused beams. For the same reasons as those described with reference to FIGS. 2( a) and 2(b), the lens 24 is provided at the convergence point 60 to convert each of the plurality of laser beams 40 emitted from the light-guiding member 30 toward the user's eye 70 into approximately parallel beams. The plurality of laser beams 40 that have passed through the lens 24 enter the light-guiding member 30.

[0049] The light-guiding member 30 is formed of a glass material such as cycloolefin polymer (COP) resin or acrylic resin. The laser light 40 passes through the light-guiding member 30. The light-guiding member 30 has multiple reflective surfaces 32, 34, and 36. The reflective surfaces 32, 34, and 36 are formed, for example, by depositing a reflective material on a glass material. The laser light 40 is reflected within the light-guiding member 30 by the reflective surfaces 32, 34, and 36 in that order, and is then emitted from the light-guiding member 30 to the outside. The reflective surfaces 32 and 34 are substantially flat and arranged substantially parallel to each other. The reflective surfaces 32 and 34 are, for example, substantially parallel to the user's face. On the other hand, the reflective surface 36 is a concave curved surface such as a free-form surface. The substantially flat surface means a surface that is flat enough not to impart focusing power to the laser light 40. "Approximately parallel" means that the inclination is ±5° or less, or may be ±3° or less, or may be ±1° or less.

[0050] Each of the multiple laser beams 40 incident on the light-guiding member 30 travels toward the reflecting surface 32 while converging. Each of the multiple laser beams 40 is converged near the reflecting surface 32. For example, a laser beam 40a corresponding to the center of the image projected onto the retina (which can also be said to be the laser beam when the deflection angle of the scanning unit 12 is 0°) is converged on the reflecting surface 32. Each of the multiple laser beams 40 reflected by the reflecting surface 32 travels toward the reflecting surface 34. For example, all of the multiple laser beams 40 are converged just before reaching the reflecting surface 34, and then become diffused light before entering the reflecting surface 34. Each of the multiple laser beams 40 reflected by the reflecting surface 34 is incident on the reflecting surface 36 as diffused light.

[0051] The reflecting surface 36 is a concave curved surface and therefore has a positive focusing power. Therefore, each of the multiple laser beams 40 reflected by the reflecting surface 36 is converted from diffused light into approximately parallel light, and the multiple laser beams 40 converge at a convergence point 62 in the user's eye 70. The convergence point 62 is located, for example, near the pupil 74. Because the laser beams 40 traveling to the eye 70 are approximately parallel light, the laser beams 40 are converted from approximately parallel light to convergent light by the crystalline lens 76 and focused near the retina 72. This allows the user to view an image.

[0052] In order to increase the viewing angle of the image projected onto the retina 72, the curvature of the reflecting surface 36 is set so that the convergence angle α2 at which the multiple laser beams 40 converge at the convergence point 62 is larger than the scanning angle α1 of the scanning unit 12.

[0053] The reflecting surface 34 has an area 34a that reflects the laser light 40 reflected by the reflecting surface 32 toward the reflecting surface 36, and an area 34b that transmits the laser light 40 reflected by the reflecting surface 36, with the areas 34a and 34b partially overlapping. This overlapping area 34c is required to have both the function of reflecting and the function of transmitting the laser light 40. The angle of incidence at which the laser light 40 reflected by the reflecting surface 32 is incident on the reflecting surface 34 is larger than the angle of incidence at which the laser light 40 reflected by the reflecting surface 36 is incident on the reflecting surface 34. Therefore, by imparting angle dependency such that at least the area 34c of the reflecting surface 34 mainly reflects the laser light 40 with a large angle of incidence and mainly transmits the laser light 40 with a small angle of incidence, it is possible to both reflect the laser light 40 reflected by the reflecting surface 32 and transmit the laser light 40 reflected by the reflecting surface 36. Furthermore, it is sufficient that the laser light 40 reflected by the reflecting surface 36 is projected onto the retina 72, and even if the laser light 40 reflected by the reflecting surface 32 passes through the reflecting surface 34, there is substantially no effect. Therefore, by using a half mirror for the reflecting surface 34, it is possible to both reflect the laser light 40 reflected by the reflecting surface 32 and transmit the laser light 40 reflected by the reflecting surface 36.

[0054] Here, an example of dimensions of the image projection device 100 will be described. FIG. 9 is a diagram showing an example of dimensions of the image projection device 100 according to the first embodiment. The following example of dimensions is an example assuming that the refractive index of the light-guiding member 30 is approximately 1.5 to 1.55. Each dimension indicates the length of the trajectory of the axis of the laser light 40a corresponding to the center of the image projected onto the retina 72. As shown in FIG. 9, the length L1 between the scanning unit 12 and the reflecting mirror 20 is 6 mm to 9 mm, for example, 7.5 mm. The length L2 between the reflecting mirror 20 and the incident surface 31a of the light-guiding member 30 is 10.7 mm to 16 mm, for example, 13.4 mm. The length L3 of the lens 24 is 2.4 mm to 3.6 mm, for example, 3 mm. The length L4 between the incident surface 31a of the light-guiding member 30 and the reflecting surface 32 is 10 mm to 14.8 mm, for example, 12.4 mm. The length L5 between the reflecting surfaces 32 and 34 is 6 mm to 9 mm, for example, 7.6 mm. The length L6 between the reflecting surfaces 34 and 36 is 4.3 mm to 6.5 mm, for example, 5.4 mm. The length L7 between the reflecting surface 36 and the exit surface 31b of the light-guiding member 30 is 2.8 mm to 4.2 mm, for example, 3.5 mm. The length L8 from the exit surface 31b of the light-guiding member 30 to the cornea 78 of the eye 70 is 6.7 mm to 10 mm, for example, 8.4 mm. The incident angle θ1 of the laser light 40a to the reflecting mirror 20 is 20° to 30°, for example, 25°. The incident angle θ2 of the laser light 40a to the reflecting surface 32 and the incident angle θ3 to the reflecting surface 34 are 40° to 60°, for example, 50°. The incident angle θ4 of the laser light 40a on the reflecting surface 36 is 20° to 30°, for example 25°. Note that the dimensions from L2 to L7 in FIG. 9 will have the same design results if the optical path length, i.e., the sum of the product of the refractive index and the distance, is constant. This fact may be utilized to fine-tune the dimensions.

[0055] Thus, for example, the lengths L4, L5, L6, and L7 within the light-guiding member 30 become shorter in this order. For example, the incident angle θ1 of the laser light 40a on the reflecting mirror 20 and the incident angle θ4 on the reflecting surface 36 are approximately the same, and the incident angle θ2 on the reflecting surface 32 and the incident angle θ3 on the reflecting surface 34 are approximately the same, with the incident angles θ2 and θ3 being approximately twice the incident angles θ1 and θ4. This allows a high-quality image to be projected onto the retina 72. The incident angles being approximately the same and approximately twice as large mean that a high-quality image can be projected onto the retina 72.

[0056] As shown in FIG. 8 , the direction of the laser light 40a corresponding to the center of the image projected onto the retina 72, reflected by the scanning unit 12 and traveling toward the reflecting mirror 20, is substantially parallel to the direction of the laser light 40a reflected by the reflecting surface 36 of the light-guiding member 30 and traveling toward the eye 70. The reflecting surface 34 is disposed substantially perpendicular to the laser light 40a as it reflects off the reflecting surface 36 of the light-guiding member 30 and travels toward the eye 70. The reflecting surface 32 is disposed substantially parallel to the reflecting surface 34. This configuration enables a high-quality image to be projected onto the retina 72. "Substantially parallel" refers to an inclination of ±5° or less, and may also be ±3° or less, or ±1° or less. "Substantially perpendicular" refers to an intersection angle of 90°±5°, 90°±3°, or 90°±1°.

[0057] Furthermore, the laser beam 40a corresponding to the center of the image projected onto the retina 72 is incident on the incident surface 31a of the light-guiding member 30 at an angle substantially perpendicular to the incident surface 31a. "Substantially perpendicular" refers to an angle of 90°±5°, or may also be an angle of 90°±3°, or may also be an angle of 90°±1°. The effect of this will be explained using FIGS. 10(a) to 11(b). FIGS. 10(a) and 11(a) are diagrams showing optical systems 800 and 810 used in simulations, and FIGS. 10(b) and 11(b) are simulation results evaluating the laser beam 140 irradiated onto the projection surface 164 in the optical system 800 of FIG. 10(a) and the optical system 810 of FIG. 11(a).

[0058] 10(a) and 11(a), in the optical systems 800 and 810 used in the simulation, the plurality of laser beams 140 are assumed to be reflected by the reflecting mirror 120, converge at a convergence point 160, and then enter the light-guiding member 130 from the incident surface 131a. The light-guiding member 130 has a reflecting surface 136, and the plurality of laser beams 140 are assumed to be reflected by the reflecting surface 136, converge at a convergence point 162, and then projected onto the projection surface 164. In the optical system 800 of FIG. 10(a), the incident surface 131a of the light-guiding member 130 is assumed to be inclined to one side with respect to the laser beams 140a when the deflection angle of the scanning unit 112 is 0°. In the optical system 810 of FIG. 11(a), the incident surface 131a of the light-guiding member 130 is assumed to be inclined to the other side with respect to the laser beams 140a when the deflection angle of the scanning unit 112 is 0°.

[0059] As shown in Figures 10(b) and 11(b), when the laser light 140a is incident on the light-guiding member 130 at an angle, deviations and deviation angles occur in the multiple laser light beams 140 irradiated onto the projection surface 164.

[0060] From these simulation results, it can be seen that in the image projection device 100 of Example 1, in order to project a high-quality image onto the retina 72, it is preferable that the laser light 40a is incident approximately perpendicularly on the incident surface 31a of the light-guiding member 30.

[0061] FIG. 12 is a diagram showing a state in which the image projection device 100 according to the first embodiment is attached to an eyeglass frame 90. As shown in FIG. 12, the eyeglass frame 90 has temples 92 and a rim 94. The scanning unit 12 and the reflecting mirror 20 are attached to the eyeglass frame 90 near the temples 92. The light guide member 30 is attached to the eyeglass frame 90 near the rim 94. The light source 10, the scanning unit 12, the lens 14, the reflecting mirror 16, the reflecting mirror 20, and the lens 24 are housed in a housing 96 for protecting them and the laser beam 40. By attaching the housing 96 to the eyeglass frame 90, the optical components in the housing 96 are attached to the eyeglass frame. The light guide member 30 is made of a glass material, and the laser beam 40 passes through the inside of the light guide member 30; therefore, most of the light guide member 30 is not located within the housing 96. The majority of the light-guiding member 30 not being located within the housing 96 means that 80% or more of the light-guiding member 30 is not located within the housing 96, or alternatively, 85% or more of the light-guiding member 30 is not located within the housing 96, or alternatively, 90% or more of the light-guiding member 30 is not located within the housing 96.

[0062] The laser light 40 travels inside the light-guiding member 30 while being reflected by the reflecting surfaces 32 to 36, so that the reflecting mirror 20 and the lens 24 can be arranged at a position away from the user's face. Furthermore, the housing 96 that houses the reflecting mirror 20, the lens 24, etc. inside is provided at a distance from the user's face, since the reflecting mirror 20, the lens 24, etc. are arranged at a position away from the user's face. Therefore, a sufficient clearance can be secured between the housing 96 and the user's face, and interference of the housing 96 with the user's face can be suppressed. Furthermore,

[0063] Because the light-guiding member 30 is made of a glass material, most of the light-guiding member 30 does not need to be housed within the housing 96. If an attempt is made to increase the viewing angle of the image projected onto the retina 72, the distance between the eye 70 and the light-guiding member 30 (length L8 in FIG. 9 ) becomes shorter; however, because most of the light-guiding member 30 is not housed within the housing 96, even if the viewing angle of the image is increased, the distance between the eye 70 and the light-guiding member 30 can be maintained at a length (for example, 8 mm or more) that makes it difficult for eyelashes to interfere with the light-guiding member 30.

[0064] Furthermore, since the light-guiding member 30 made of a glass material is placed in front of the user's eyes and the laser light 40 is irradiated onto the retina 72 after being reflected multiple times within the light-guiding member 30, the light-guiding member 30 has a shape that extends along the user's face. Therefore, compared to a case where the laser light is reflected by a projection mirror placed in front of the user's eyes and then irradiated onto the retina 72, as in Comparative Example 2, the image projection device 100 does not protrude forward in front of the user's eyes. Furthermore, since the laser light 40 travels within the light-guiding member 30, the light-guiding member 30 does not need to be covered by the housing 96, and in this respect as well, the image projection device 100 does not protrude forward in front of the user's eyes. This allows for improved design.

[0065] As described above, according to the first embodiment, as shown in FIG. 8 , the plurality of laser beams 40 (image beams) scanned by the scanning unit 12 are converged by the reflecting mirror 20 (first optical member) at a convergence point 60 (second convergence point) in front of the light-guiding member 30 and then enter the light-guiding member 30. The light-guiding member 30 is formed of a glass material through which the laser beams 40 pass. The plurality of laser beams 40 reflected by the plurality of reflecting surfaces 32, 34, 36 are converged at a convergence point 62 (first convergence point) within the eye 70 and then irradiated onto the retina 72. The convergence point 60 is provided with a lens 24 (second optical member) that causes the laser beams 40 to enter the final reflecting surface 36 of the light-guiding member 30 as diffused light. By providing the lens 24 at the convergence point 60, the NA of the laser beams 40 when they enter the final reflecting surface 36 of the light-guiding member 30 can be adjusted to an appropriate value, and the plurality of laser beams 40 reflected by the reflecting surface 36 can be made into approximately parallel beams. Therefore, a high-quality image can be projected. By providing the light-guiding member 30 made of a glass material through which the laser light 40 passes, at the rear stage of the lens 24, as shown in Fig. 12, most of the light-guiding member 30 does not need to be housed in the housing 96, and therefore, a sufficient clearance can be secured between the image projection device 100 and the user's face.

[0066] In the first embodiment, as shown in FIG. 12 , the scanning unit 12 and the reflecting mirror 20 are attached near the temples 92 of the eyeglass frame 90, and the light-guiding member 30 is attached near the rim 94 of the eyeglass frame 90. The light-guiding member 30 has a shape that extends from in front of the user's eyes 70 toward the temples 92 of the eyeglass frame 90. This allows the scanning unit 12, the reflecting mirror 20, the lens 24, and the light-guiding member 30 to be positioned along the contours of the user's face. This ensures sufficient clearance between the image projection device 100 and the user's face. Furthermore, the image projection device 100 can be made smaller.

[0067] 12, the light-guiding member 30 has an odd number of reflecting surfaces 32, 34, 36, and receives a plurality of laser beams 40 that are reflected by the reflecting mirror 20 and travel diagonally forward. As a result, the laser beams 40 travel inside the light-guiding member 30 from the temple 92 side of the eyeglass frame 90 toward the eye 70 side, and the scanning unit 12, the reflecting mirror 20, the lens 24, and the light-guiding member 30 can be arranged along the contours of the user's face.

[0068] 8, the final reflective surface 36 of the plurality of reflective surfaces 32, 34, 36 of the light-guiding member 30 is a concave curved surface, and the remaining reflective surfaces 32, 34 are substantially flat surfaces. This allows the laser light 40 to travel inside the light-guiding member 30 from the temple 92 side of the eyeglass frame 90 toward the eye 70 side, and allows the scanning unit 12, reflective mirror 20, lens 24, and light-guiding member 30 to be arranged along the contours of the user's face. It is preferable that the reflective surfaces 32 and 34 are substantially parallel to each other.

[0069] 8, in the first embodiment, the reflecting surface 34 (first reflecting surface) immediately before the final reflecting surface 36 has a region 34c onto which both the laser light 40 reflected by the reflecting surface 32 immediately before it (second reflecting surface) and the laser light 40 reflected by the final reflecting surface 36 are incident. In the region 34c, the reflecting surface 34 reflects the laser light 40 reflected by the reflecting surface 32 onto the reflecting surface 36 and transmits the laser light 40 reflected by the reflecting surface 36. This allows the multiple laser light beams 40 to converge at the convergence point 62 and be irradiated onto the retina 72. Furthermore, the light-guiding member 30 can be made smaller.

[0070] Furthermore, in the first embodiment, the reflecting surface 34 is substantially perpendicular to the optical axis of the laser beam 40a (center image ray) corresponding to the center of the image after it is reflected by the reflecting surface 36. This allows the plurality of laser beams 40 to be converged to the convergence point 62 even if the plurality of laser beams 40 reflected by the reflecting surface 36 are refracted when they are emitted from the light-guiding member 30.

[0071] Furthermore, in the first embodiment, the convergence angle α2 at which the multiple laser beams 40 converge at the convergence point 62 is larger than the scanning angle α1 of the multiple laser beams 40 by the scanning unit 12. This makes it possible to increase the viewing angle of the image projected onto the retina 72. Furthermore, since most of the light-guiding member 30 does not need to be housed within the housing 96, even if the convergence point 62 is moved closer to the light-guiding member 30 to increase the viewing angle of the image, a sufficient clearance can be secured between the image projection device 100 and the user's face. Note that the magnitude of the convergence angle α2 may be equal to or larger than the scanning angle α1.

[0072] 12, the laser light 40 travels diagonally forward from a side closer to the user's face than the scanning unit 12 attached near the temples 92 of the eyeglass frame 90, and enters the scanning unit 12, then travels rearward from the scanning unit 12, is reflected diagonally forward by the reflecting mirror 20, and enters the light-guiding member 30 attached near the rim 94 of the eyeglass frame 90. As a result, for the same reasons as those explained in FIGS. 7(a) and 7(b), a high-quality image with reduced distortion can be projected onto the retina 72. [Example]

[0073] FIG. 13 is a diagram illustrating an image projection device 200 according to a second embodiment. In the image projection device 200 according to the second embodiment, as illustrated in FIG. 13, a light-guiding member 30a includes a main body 38 in which a plurality of laser beams 40 incident on an incident surface 31a travel while being reflected by the reflecting surfaces 32 to 36 to be irradiated onto a user's eye 70, and a cover 39 attached to the main body 38 so as to cover the reflecting surfaces 32 and 36 from the outside. The main body 38 and the cover 39 are formed of glass materials having substantially the same refractive index, for example, the same glass material. An exit surface 31b, from which the plurality of laser beams 40 reflected by the reflecting surface 36 exit the main body 38, is flatter than the reflecting surface 36. A surface 39a of the cover 39 opposite to the reflecting surface 36 from the exit surface 31b of the main body 38 is flatter than the reflecting surface 36. The surface 39a of the cover portion 39 and the light exit surface 31b of the main body portion 38 are, for example, substantially parallel and substantially flat surfaces. Also, the reflecting surfaces 32 to 36 are all half mirrors. The other configurations are the same as those in the first embodiment, so a description thereof will be omitted.

[0074] Fig. 14 is a diagram illustrating a case where a user views the outside world through the light-guiding member 30a in Example 2. As shown in Fig. 14, the light-emitting surface 31b of the main body 38, the reflecting surface 36, and the surface 39a of the cover 39 are located in front of the user's eye 70. The refractive indexes of the main body 38 and the cover 39 are approximately the same, and the surface 39a of the cover 39 and the light-emitting surface 31b of the main body 38 are highly flat. This allows the user to view the outside world through the reflecting surface 36, which is a half mirror, as in line of sight 79, without feeling any discomfort.

[0075] According to the second embodiment, the light-guiding member 30a includes a main body 38 through which multiple laser beams 40 pass after repeatedly reflecting off multiple reflecting surfaces 32 to 36 and then irradiating the user's retina 72, and a cover 39 that covers the final reflecting surface 36 and has a refractive index substantially equal to that of the main body 38. The reflecting surface 36 is a half mirror, and the surface 39a of the cover 39 and the exit surface 31b of the main body 38 are flatter than the reflecting surface 36. This allows the user to view the outside world while minimizing discomfort, as shown in FIG. 14 . This allows for support for augmented reality (AR), which displays virtual visual information superimposed on real scenery. The refractive indexes of the main body 38 and the cover 39 being substantially equal means that the refractive indexes are the same enough to allow the user to view the outside world while minimizing discomfort, and this refers to a difference in refractive index of 0.05 or less.

[0076] Furthermore, in the second embodiment, the surface 39a of the cover unit 39 and the light exit surface 31b of the main body unit 38 are generally parallel to each other and generally flat. This allows the user to view the outside world with even less discomfort. The surface 39a of the cover unit 39 may be a concave or convex curved surface according to the user's corrective power in order to correct the user's eyesight. Therefore, the term "the surface 39a of the cover unit 39 is generally flat" refers to a surface that is flat enough to allow the user to view the outside world with less discomfort, including cases where the surface is curved to the extent of vision correction. The term "the surface 39a of the cover unit 39 and the light exit surface 31b of the main body unit 38 are generally parallel to each other" refers to a surface that is parallel enough to allow the user to view the outside world with less discomfort, even when the surface 39a of the cover unit 39 is curved to the extent of vision correction.

[0077] Furthermore, as in the above-described second embodiment, it is preferable that the cover portion 39 covers both the reflective surfaces 32 and 36. This reduces the sense of incongruity that occurs at the boundary between the reflective surfaces 32 and 36 when the user views the outside world.

[0078] In the second embodiment, the main body 38 may be formed entirely by integral molding, or the first portion 38a having a substantially flat reflecting surface and the second portion 38b having the free-form reflecting surface 36 may be molded separately and then bonded together. Molding the first portion 38a and the second portion 38b using separate molds and then bonding them together improves ease of manufacture. On the other hand, forming the entire main body 38 by integral molding improves mass productivity. [Example]

[0079] FIG. 15 is a diagram illustrating an image projection device 300 according to a third embodiment. In the image projection device 300 of the third embodiment, as illustrated in FIG. 15 , the light-guiding member 30a includes a main body 38 and a cover 39, similar to the second embodiment. The main body 38 includes a reflecting surface 34 located closer to the user's eye 70 and a reflecting surface 32 located farther from the user's eye 70, onto which the laser beams 40 are incident before they are incident on the final reflecting surface 36. The cover 39 differs from the second embodiment in that it includes a reflecting surface 37 on the opposite side of the reflecting surface 36 from the exit surface 31b of the main body 38. The reflecting surface 37 is a flat surface, similar to the reflecting surfaces 32 and 34, and is substantially flush with the reflecting surface 32. The reflecting surfaces 32, 34, 36, and 37 all reflect a portion of the incident laser beam 40 and transmit the remainder. The plurality of laser beams 40 are reflected by the plurality of reflecting surfaces 32, 34, 36, and 37 the same number of times and are then irradiated onto the eye 70.

[0080] When attempting to thin the light-guiding member 30a, extend it laterally to reduce interference with the user's face, and / or ensure a sufficient viewing angle, the number of reflections of the laser light 40 within the light-guiding member 30a increases. In this case, when attempting to converge the multiple laser light beams 40 to the convergence point 62, some of the multiple laser light beams 40, such as laser light beam 40c, enter the reflecting surface 36 from the eye 70 side, pass through it, reflect off the reflecting surface 37 of the cover portion 39, and then re-enter the reflecting surface 36 from the opposite side of the eye 70 (the opposite surface), pass through it, reflect off the reflecting surface 34, and then reflect off the reflecting surface 36 to be irradiated onto the eye 70. The remaining laser light beams 40a and 40b of the multiple laser light beams 40 do not pass through the reflecting surface 36 but are reflected off the reflecting surface 36 and irradiated onto the eye 70. Although not shown in the figure, some of the laser light beams 40a and 40b also pass through the reflecting surface 36, but this light does not irradiate the retina 72 and need not be taken into consideration.

[0081] In order to reduce variations in brightness on the image projected onto the retina 72, it is preferable to minimize the difference in brightness between the laser beams 40a and 40b that do not pass through the reflecting surface 36 but are reflected by the reflecting surface 36 and irradiate the eye 70, and the laser beam 40c that passes through the reflecting surface 36 and is reflected by the reflecting surface 36 and irradiates the eye 70 when they enter the eye 70. On the other hand, it is preferable that the light intensity of the laser beams 40a to 40c that enter the eye 70 is relatively high. Furthermore, when viewing the outside world through the light-guiding member 30a, it is preferable that the transmittance of the light-guiding member 30a be approximately 10% to 30%. Therefore, a method for achieving this will be described below.

[0082] In the following, it is assumed that laser light 40a to 40c is reflected a total of four times by reflecting surfaces 32, 34, and 37, and is irradiated onto eye 70 by the fifth reflection by final reflecting surface 36. The reflectance of each surface is defined as follows: For simplicity, the sum of the transmittance and reflectance of the same surface is assumed to be 1 (transmittance + reflectance = 1). The amount of incident light of the laser beams 40a to 40c on the incident surface 31a is Pi Transmittance of the incident surface 31a: Tp Reflectance of the incident surface 31a: Rp (=1-Tp) Transmittance of the reflecting surface 34: Ta Reflectance of the reflecting surface 34: Ra (=1-Ta) Transmittance of the reflecting surface 32: Tb Reflectance of the reflecting surface 32: Rb (= 1 - Tb) Transmittance of the reflecting surface 36: Tc Reflectance of the reflecting surface 36: Rc (= 1 - Tc) Transmittance of the reflecting surface 37: Td Reflectance of the reflecting surface 37: Rd (= 1 - Td)

[0083] In this case, the light intensity Pcr when the laser beams 40a and 40b that are reflected by the reflecting surface 36 without passing through the reflecting surface 36 are irradiated onto the eye 70 is Pcr=Pi×Tp×Ta×Rb×Ra×Rb×Ra×Rc×Ta...(1) This becomes: On the other hand, the light amount Pct of the laser light 40c that is transmitted through the reflecting surface 36, then re-enters the reflecting surface 36 and is reflected by the reflecting surface 36 when it is irradiated onto the eye 70 is Pct=Pi×Tp×Ta×Rb×Ra×Tc×Rd×Tc×Ra×Rc×Ta...(2) This becomes:

[0084] Here, for simplicity, it is assumed that the transmittance Tp of the incident surface 31a is 1. In this case, the formulas (1) and (2) can be transformed as follows: Pcr / Pi=Ta×Rb×Ra×Rb×Ra×Rc×Ta...(3) Pct / Pi=Ta×Rb×Ra×Tc×Rd×Tc×Ra×Rc×Ta...(4) To suppress uneven brightness on the image projected onto the retina 72, it is preferable that the formula (3) / formula (4) is close to 1. Furthermore, since formulas (3) and (4) are the ratio of the amount of light irradiated onto the eye 70 to the amount of incident light, it is preferable that they are large.

[0085] The fact that equation (3) / equation (4) is close to 1 can be expressed as follows. Pcr / Pct=Rb / (Tc×Rd×Tc)≒1...(5) Here, the reflecting surface 32 and the reflecting surface 37 are the same continuous surface, and since the user sees the outside world through the reflecting surface 32 and the reflecting surface 37, it is preferable that the reflectance is approximately the same. Therefore, in the following, Rb = Rd. In this case, the formula (5) becomes as follows: Pcr / Pct=Tc 2 ≒1···(5´) Tc=1 means that the reflectance on the reflective surface 36 is zero, and the laser beams 40a to 40c are not reflected by the reflective surface 36 and are not projected onto the retina 72. Therefore, it is preferable to set Tc to a value smaller than 1 while taking into consideration the balance.

[0086] Here, when a user views the outside world through light-guiding member 30a, for example, for AR (Augmented Reality), light from the outside world reaches user's eye 70 via reflective surfaces 32, 37, 36, and 34. It is generally said that a transmittance of light from the outside world of about 10% to 30% is appropriate for sunglasses. The transmittance Tar of reflective surfaces 32, 37, 36, and 34 is expressed as follows: Tar=Td×Tc×Ta=(1-Rd)×(1-Rc)×(1-Ra)...(6)

[0087] Based on the above, the ranges of Ra, Rb, Rc, and Rd are shown below.

[0088] [Rc range] It is known that the human visual sensitivity is such that a luminance difference of about 70% to 80% is not very noticeable. 2 is (1-Rc) 2 This can be transformed into Pcr / Pct=(1-Rc) 2 This can be expressed in a graph as shown in Figure 16. From Figure 16, it can be seen that the following range of Rc is preferable in order to keep the luminance difference to about 70% to 80%. Rc≦15%

[0089] [Ra range] As described above, it is preferable that the value of formula (3) is large in terms of the amount of light irradiated onto the eye 70. Rc in formula (3) is subject to the above-mentioned constraints, and Rb will be described later, but at least Ta×Ra×Ra×Ta=(1−Ra) is included in formula (3). 2 ×Ra 2 In this case, since the maximum value is reached when Ra=0.5, it can be said that the following range of Ra is preferable. 45%≦Ra≦55%

[0090] [Rb range] FIG. 17(a) shows the relationship between Rc and Pcr / Pi when Ra in equation (3) is fixed at 50% and Rb is changed to 30%, 40%, 50%, 60%, 70%, and 80%. As mentioned above, equation (3) indicates the ratio of the amount of light irradiated onto the eye 70 to the amount of incident light, so a large value is preferable. Even considering that the laser output of the light source 10 is several mW and the amount of light irradiated onto the eye 70 is attenuated to approximately 1 / 10,000 of several mW, it is preferable that the ratio of the amount of light irradiated onto the eye 70 to the amount of incident light is approximately 0.1%. Therefore, from FIG. 17(a), it can be said that Rb is preferably Rb≧50%.

[0091] Figure 17(b) shows the relationship between Rc and Tar when Ra in equation (6) is fixed at 50% and Rb is changed to 30%, 40%, 50%, 60%, 70%, and 80%. As mentioned above, the transmittance of light from the outside world is appropriate to be approximately 10% to 30%. Therefore, from Figure 17(b), it can be said that Rb is preferably 40%≦Rb≦70%.

[0092] Therefore, from FIGS. 17(a) and 17(b), it can be said that the following ranges of Rb are preferable. 50%≦Rb≦70% Furthermore, as described above, it is preferable that Rb and Rd are equal because the user sees the outside world through the continuous surfaces of reflecting surface 32 and reflecting surface 37. Therefore, it can be said that the following range of Rd is preferable. 50%≦Rd≦70%

[0093] From the above, Range of reflectance Ra of reflective surface 34 (first reflective surface): 45%≦Ra≦55% Range of reflectance Rb of reflecting surface 32 (second reflecting surface): 50%≦Rb≦70% Reflectance Rc range of the reflecting surface 36 (final reflecting surface): 5%≦Rc≦15% The range of reflectance Rd of the reflecting surface 37 (third reflecting surface): 50%≦Rd≦70% It can be said that is preferable.

[0094] According to the third embodiment, a portion of the plurality of laser beams 40, namely, laser beam 40c, passes through reflecting surface 36 and then re-enters reflecting surface 36, where it is reflected and irradiated onto retina 72, while the remaining laser beams 40a and 40b do not pass through reflecting surface 36 but are reflected and irradiated onto retina 72. In this case, when laser beams 40a to 40c enter eye 70, the ratio of the luminance of laser beam 40c to the luminance of laser beams 40a and 40b is set to 80% or more. This makes it possible to suppress luminance variations on the image projected onto retina 72.

[0095] The reflectance Rc of the reflective surface 36 is set to 15% or less. By setting the reflectance Rc of the reflective surface 36 to 15% or less, the luminance difference between the laser light 40c that passes through the reflective surface 36 and is reflected by the reflective surface 36 and the laser light 40a, 40b that is reflected by the reflective surface 36 without passing through the reflective surface 36 can be reduced to approximately 70%, as shown in FIG. 16 . This reduces the luminance variation in the image projected onto the retina 72. To reduce the luminance difference, Rc is preferably set to 13% or less, more preferably 12% or less, and even more preferably 10% or less. On the other hand, if Rc is too small, the amount of laser light 40 reflected by the reflective surface 36 decreases. In order to ensure the amount of laser light 40 irradiated onto the eye 70, the output of the light source 10 must be increased, for example. Therefore, Rc is preferably set to 5% or more, more preferably 8% or more, and even more preferably 10% or more.

[0096] The reflectance Rb of the reflective surface 32 and the reflectance Rd of the reflective surface 37 are made to be approximately the same magnitude. This makes it possible to minimize the difference in brightness that occurs among the laser beams 40a to 40c due to the presence or absence of reflection from the reflective surface 37, even when the laser beams 40a and 40b are not reflected by the reflective surface 37 and the laser beam 40c is reflected by the reflective surface 37. "Approximately the same magnitude" means that the ratio of the reflectance Rd of the reflective surface 37 to the reflectance Rb of the reflective surface 32 is 95% to 105%, or may be 98% to 102%.

[0097] The reflectance Rb of the reflective surface 32 and the reflectance Rd of the reflective surface 37 are set to 40% or more and 70% or less. This allows the outside world to be seen with appropriate brightness when viewed through the light-guiding member 30a in AR or the like.

[0098] In order to minimize the difference in brightness between the multiple laser beams 40 irradiated onto the eye 70, to ensure a large amount of light of the laser beams 40 when they enter the eye 70, and to ensure visibility when viewing the outside world through the light-guiding member 30a, it is preferable that the reflectance Ra of the reflective surface 34 be 45% or more and 55% or less, the reflectances Rb and Rd of the reflective surfaces 32 and 37 be 50% or more and 70% or less, and the reflectance Rc of the reflective surface 36 be 5% or more and 15% or less.

[0099] In the above-mentioned first and second embodiments, the reflecting mirror 20 may be any optical element other than a curved mirror, such as a combination of lenses or mirrors, or a diffractive element, as long as it has a positive focusing power and an optical property of converging and then diffusing the plurality of laser beams 40.

[0100] In the above-described first and second embodiments, the lens 24 may have a function of suppressing chromatic aberration. Furthermore, the lens 24 is preferably designed to suppress curvature of field. The lens 24 may be another optical element such as a mirror or a diffraction element, as long as it can cause the laser light 40 to be incident on the reflecting surface 36 of the light-guiding member 30 as diffused light.

[0101] In the above-mentioned first and second embodiments, the image projection device 100 is attached to an eyeglass-type frame 90 as an example. However, as long as this frame can be worn on the user's face and the image projection device 100 can be placed in front of the user's eyes, it is not limited to eyeglass-type, and may be other types such as goggle-type, eye patch-type, ear hook-type, and helmet-mounted type.

[0102] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0103] 10, 110 light source 12, 112 Scanning unit 14, 114 lenses 16, 116 Reflective mirror 20, 120 Reflective mirror 122, 122a Projection mirror 24, 124 lenses 30, 30a, 130 Light guide member 31a, 131a entrance plane 31b Output surface 32, 34, 36, 37, 136 reflective surface 34a, 34b, 34c areas 38 Main body 38a Part 1 38b Part 2 39 Cover 39a side 40, 40a, 40b, 40c, 140, 140a laser light 50 control section 52 Image input unit 60, 62, 160, 162 Convergence points 164 Projection surface 70 eyes 72 Retina 74 Pupil 76 Crystalline lens 78 Cornea 79 line of sight 90, 190 eyeglass frames 92, 192 Temple 94, 194 rims 96, 196 cabinet 100, 200, 300 Image projection device 500, 600, 700, 710, 720, 800, 810 optics

Claims

1. A light source and a control unit that generates an image light beam based on image data and controls emission of the image light beam from the light source; a scanning unit that scans the image light beam emitted from the light source two-dimensionally; a light guiding member formed of a glass material through which the plurality of image light rays emitted from the scanning unit at different times pass, the light guiding member having a plurality of reflective surfaces that reflect the plurality of image light rays, the plurality of reflective surfaces including a reflective surface having a positive light-collecting power, the light guiding member converging the plurality of image light rays reflected by the plurality of reflective surfaces at a first convergence point in the eye of the user and then irradiating the image light rays onto the retina of the user; a first optical member that causes the plurality of image light rays emitted from the scanning unit to converge at a second convergence point in front of the light guiding member and then enter the light guiding member; and a second optical member disposed at the second convergence point and configured to cause each of the plurality of image light rays to be incident as diffused light onto a reflecting surface having the positive light-collecting power among the plurality of reflecting surfaces provided on the light-guiding member.

2. the scanning unit and the first optical member are attached near temples of a frame that is worn on the user's face, The image projection device according to claim 1 , wherein the light guide member is attached to the frame in the vicinity of a rim and has a shape extending from in front of the user's eyes toward the temples.

3. The image projection device according to claim 2 , wherein the light guide member has an odd number of reflecting surfaces as the plurality of reflecting surfaces, and the plurality of image light rays that are reflected by the first optical member and travel obliquely forward are incident on the light guide member.

4. 4. The image projection device according to claim 1, wherein the remaining reflecting surfaces of the plurality of reflecting surfaces other than the reflecting surface having the positive light-collecting power are substantially flat surfaces.

5. The image projection device according to claim 4 , wherein the remaining reflective surfaces are substantially parallel to each other.

6. the light guiding member includes a main body portion through which the plurality of image light rays pass and are irradiated onto the retina of the user after being repeatedly reflected on the plurality of reflecting surfaces, and a cover portion that covers the reflecting surfaces having positive light-collecting power and has a refractive index that is substantially the same as that of the main body portion, an exit surface, through which the plurality of image light rays reflected by the reflecting surface having the positive light-collecting power exit from the main body, and a surface of the cover part opposite to the exit surface of the main body with respect to the reflecting surface having the positive light-collecting power, are located in front of an eye of the user; the plurality of reflective surfaces are half mirrors, The image projection device according to claim 4 , wherein the light exit surface of the main body and the opposite surface of the cover are flatter than the reflecting surface having the positive light-collecting power.

7. The image projection device according to claim 6 , wherein the light exit surface of the main body and the opposite surface of the cover are substantially parallel to each other and are substantially flat surfaces.

8. The image projection device according to claim 6 , wherein the opposite surface of the cover portion is a curved surface that can correct the user's vision.

9. The image projection device according to claim 4 , wherein a magnitude of a convergence angle at which the plurality of image light rays converge at the first convergence point is equal to or greater than a magnitude of a scanning angle of the plurality of image light rays by the scanning unit.

10. a housing attached to the frame and accommodating the scanning unit, the first optical member, and the second optical member therein; The image projection device according to claim 2 , wherein a majority of the light guide member is not located inside the housing.

11. A light source and a control unit that generates an image light beam based on image data and controls emission of the image light beam from the light source; a scanning unit that scans the image light beam emitted from the light source two-dimensionally; a light guiding member that is formed from a glass material through which the plurality of image light rays emitted from the scanning unit at different times pass, has a plurality of reflective surfaces that reflect the plurality of image light rays, the plurality of reflective surfaces including a reflective surface having a positive light collecting power, and converges the plurality of image light rays reflected by the reflective surface having the positive light collecting power that is the last to reflect the plurality of image light rays among the plurality of reflective surfaces at a convergence point in the eye of the user, and then irradiates the image light rays onto the retina of the user, an image projection device, wherein some of the plurality of image light rays transmit through the reflective surface having positive focusing power, then re-enter and transmit through the opposite side of the reflective surface having positive focusing power, are reflected by the reflective surface having positive focusing power, and are irradiated onto the retina of the user; and the remaining image light rays do not transmit through the reflective surface having positive focusing power, but are reflected by the reflective surface having positive focusing power, and are irradiated onto the retina of the user.

12. The image projection device according to claim 11 , wherein the plurality of image light rays are reflected by the plurality of reflecting surfaces an equal number of times and are then irradiated onto the user's retina.

Images