Image projection device

Abstract

An image projection device comprises: a light source (10); a control unit (50) that generates image light based on image data and controls the emission of image light from the light source; a scanning unit (12) mounted on a frame worn on a user's face and scanning the image light emitted from the light source in two dimensions; a light guide member (30) mounted on the frame and positioned in front of the user's eyes, formed of a glass material that allows image light emitted from the scanning unit at different times to pass through internally, having multiple reflective surfaces that reflect the image light, so that multiple image light reflected by the multiple reflective surfaces converge at a convergence point (62) in the user's eyes and illuminate the retina; a reflector (20) mounted on the frame, so that multiple image light emitted from the scanning unit converges at a convergence point (60) near the light guide member and is incident on the light guide member; and a lens (24) positioned at the convergence point (60), so that the image light is incident as diffused light onto the reflective surface of the last segment of the light guide member.

Description

[0001] This application is filed in accordance with Article 48 of the Implementing Regulations of the Patent Law and is a divisional application of the invention patent application "Image Projection Device" (International Application No.: PCT / JP2022 / 000691), filed on January 12, 2022, with application number 202280004786.7. Technical Field

[0002] This invention relates to an image projection device. Background Technology

[0003] An image projection device is known that scans a light beam emitted by a light source in two dimensions and projects an image onto the user's retina using Maxwell's vision. Furthermore, an image projection device capable of projecting high-quality images with suppressed distortion, defocus, etc., has been proposed, which utilizes Maxwell's vision (e.g., Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2010 / 065245 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] When the image projection device disclosed in Patent Document 1 is installed on a frame such as an eyeglass frame that is worn on the user's face, the gap between the image projection device and the user's face is likely to become smaller.

[0009] The present invention was made in view of the above-mentioned problems, and its object is to provide an image projection device that can ensure a sufficient gap between the projection device and the user's face.

[0010] means for solving problems

[0011] This invention is an image projection device comprising: a light source; a control unit that generates image light based on image data and controls the emission of the image light from the light source; a scanning unit mounted on a frame worn on a user's face and scanning the image light emitted from the light source in two dimensions; a light guide component mounted on the frame and positioned in front of the user's eyes, formed of a glass material through which multiple image light rays emitted from the scanning unit at different times pass, having multiple reflective surfaces that reflect the multiple image light rays, such that the multiple image light rays reflected by the multiple reflective surfaces converge at a first convergence point in the user's eyes and then illuminate the user's retina; a first optical component mounted on the frame, such that the multiple image light rays emitted from the scanning unit converge at a second convergence point near the light guide component and then enter the light guide component; and a second optical component positioned at the second convergence point, such that the multiple image light rays are each incident as diffused light onto the last segment of the multiple reflective surfaces of the light guide component, the last segment of the reflective surface being the last to reflect the multiple image light rays.

[0012] In the above structure, it can be configured as follows: the scanning part and the first optical component are mounted near the temple of the frame, and the light guide component is mounted near the frame of the frame, with a shape that extends from the front of the user's eyes toward the temple side.

[0013] In the above structure, it can be configured as follows: the light guide component has an odd number of reflective surfaces as the plurality of reflective surfaces, for the plurality of image light rays reflected by the first optical component and traveling obliquely forward to be incident.

[0014] In the above structure, it can be configured as follows: the last segment of the plurality of reflecting surfaces is a concave curved surface, and the remaining reflecting surfaces are approximately flat surfaces.

[0015] In the above structure, it can be configured such that the remaining reflective surfaces are approximately parallel to each other.

[0016] In the above structure, the light guide component can be configured as follows: the light guide component has: a main body through which the plurality of image rays that are repeatedly reflected by the plurality of reflective surfaces and illuminate the user's retina; and a cover that covers the reflective surface of the last segment, having a refractive index approximately the same as that of the main body, wherein the reflective surface of the last segment, the emission surface of the plurality of image rays reflected by the reflective surface of the last segment exiting from the main body, and the surface of the cover opposite to the emission surface of the main body, located in front of the user's eyes, the reflective surface of the last segment being a semi-reflective mirror, and the emission surface of the main body and the opposite surface of the cover being flatter than the reflective surface of the last segment.

[0017] In the above structure, it is possible to set the structure as follows: the ejection surface of the main body and the opposite side surface of the cover are substantially parallel to each other and are substantially flat surfaces.

[0018] In the above structure, it can be configured as follows: the first reflective surface of the last segment of the plurality of reflective surfaces has a region in which both the plurality of image rays reflected by the second reflective surface of the first reflective surface and the plurality of image rays reflected by the last segment of the reflective surface are incident, in which the plurality of image rays reflected by the second reflective surface are reflected toward the last segment of the reflective surface, and the plurality of image rays reflected by the last segment of the reflective surface are transmitted.

[0019] In the above structure, it can be configured as follows: the optical axis of the first reflective surface is approximately orthogonal to the optical axis of the central image ray corresponding to the center of the image projected onto the user's retina among the plurality of image rays after being reflected by the reflective surface of the last segment.

[0020] In the above structure, it can be configured such that the convergence angle of the plurality of image rays converging at the first convergence point is greater than or equal to the scanning angle of the scanning unit on the plurality of image rays.

[0021] In the above structure, it can be configured as follows: the image light emitted from the light source travels diagonally forward from the side closer to the user's face than the scanning unit and enters the scanning unit; the plurality of image light rays emitted from the scanning unit travel backward from the scanning unit and are reflected diagonally forward by the first optical component and enter the light guide component.

[0022] In the above structure, it can be configured as follows: the image projection device has a housing that is mounted on the frame and houses the scanning unit, the first optical component and the second optical component inside, and most of the light guide component is not located inside the housing.

[0023] In the above structure, it can be configured as follows: when the optical path length of the image light incident between the incident surface of the light guide component and the second reflective surface is set as the first optical path length, the optical path length of the image light between the second reflective surface and the first reflective surface is set as the second optical path length, the optical path length of the image light between the first reflective surface and the reflective surface of the last segment is set as the third optical path length, and the optical path length of the image light between the reflective surface of the last segment and the first reflective surface, which serves as the emission surface of the light guide component, is set as the fourth optical path length, the optical path length decreases in the order of the first optical path length, the second optical path length, the third optical path length, and the fourth optical path length.

[0024] In the above structure, it can be configured as follows: the incident angle of the image light rays incident on the first optical component is approximately the same as the incident angle of the image light rays incident on the reflective surface of the last segment, and the incident angle of the image light rays incident on the second reflective surface is approximately the same as the incident angle of the image light rays incident on the first reflective surface.

[0025] In the above structure, it can be configured as follows: a portion of the image light rays, after passing through the reflective surface of the last segment, are again incident on the opposite side of the reflective surface of the last segment and pass through, and are reflected by the reflective surface of the last segment to illuminate the user's retina; the remaining image light rays do not pass through the reflective surface of the last segment but are reflected by the reflective surface of the last segment to illuminate the user's retina; when incident on the user's eye, the brightness of the portion of the image light rays is more than 80% of the brightness of the remaining image light rays.

[0026] In the above structure, it can be configured as follows: a portion of the image light rays, after passing through the reflective surface of the last segment, are again incident on the opposite side of the reflective surface of the last segment and pass through, and are reflected by the reflective surface of the last segment to illuminate the user's retina; the remaining image light rays do not pass through the reflective surface of the last segment but are reflected by the reflective surface of the last segment to illuminate the user's retina, and the reflectivity of the reflective surface of the last segment is 15% or less.

[0027] This invention relates to 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; and a light guide member formed of a glass material through which multiple image light rays emitted from the scanning unit at different times pass, having multiple reflective surfaces that reflect the multiple image light rays. The multiple image light rays reflected by the last reflective surface of the multiple reflective surfaces converge at a convergence point in the user's eye and then illuminate the user's retina. A portion of the multiple image light rays, after passing through the last reflective surface, are again incident on the opposite side of the last reflective surface and reflected by the last reflective surface to illuminate the user's retina. The remaining image light rays do not pass through the last reflective surface but are reflected by the last reflective surface to illuminate the user's retina. When incident on the user's eye, the brightness of the portion of the image light rays is at least 80% higher than the brightness of the remaining image light rays.

[0028] This invention relates to 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; and a light guide member formed of a glass material through which multiple image light rays emitted from the scanning unit at different times pass, having multiple reflective surfaces that reflect the multiple image light rays. The multiple image light rays reflected by the last reflective surface of the multiple reflective surfaces converge at a convergence point in the user's eye and then illuminate the user's retina. The last reflective surface is the last reflective surface to reflect the multiple image light rays. A portion of the multiple image light rays, after passing through the last reflective surface, are again incident on the opposite side of the last reflective surface and are reflected by the last reflective surface to illuminate the user's retina. The remaining image light rays do not pass through the last reflective surface but are reflected by the last reflective surface to illuminate the user's retina. The reflectivity of the last reflective surface is 15% or less.

[0029] In the above structure, the plurality of reflective surfaces can be configured as follows: the plurality of reflective surfaces have: a first reflective surface located on the side closer to the user's eye; a second reflective surface located on the side farther from the user's eye, for the plurality of image rays to be incident on before being incident on the final reflective surface; and a third reflective surface for the plurality of image rays to be incident on after being transmitted through the final reflective surface, wherein the reflectivity of the second reflective surface and the reflectivity of the third reflective surface are approximately the same.

[0030] In the above structure, it is possible to set the structure as follows: the reflectivity of the second reflective surface and the reflectivity of the third reflective surface are 40% or more and 70% or less.

[0031] In the above structure, it can be configured as follows: the reflectivity of the first reflective surface is 45% or more and 55% or less, the reflectivity of the second reflective surface and the third reflective surface is 50% or more and 70% or less, and the reflectivity of the last segment's reflective surface is 5% or more and 15% or less.

[0032] In the above structure, it can be configured such that the multiple image rays are reflected the same number of times by the multiple reflective surfaces and then illuminate the user's retina.

[0033] Invention Effects

[0034] According to the present invention, the gap between the device and the user's face can be adequately ensured. Attached Figure Description

[0035] Figure 1 (a) is a diagram showing the optical system of Comparative Example 1. Figure 1 (b) is in Figure 1 The simulation results of evaluating the laser irradiated onto the projection surface in the optical system of (a).

[0036] Figure 2 (a) and Figure 2 (b) is a simulation result evaluating lasers that illuminate the projection surface at different focal lengths of lenses positioned at the convergence point.

[0037] Figure 3 (a) is a diagram showing the optical system of Comparative Example 2. Figure 3 (b) is in Figure 3 The simulation results of evaluating the laser irradiated onto the projection surface in the optical system of (a).

[0038] Figure 4 This is a diagram showing the optical system of Comparative Example 2 mounted on an eyeglass frame.

[0039] Figure 5 (a) is a diagram showing the optical system of Comparative Example 3. Figure 5 (b) is in Figure 5 The simulation results of evaluating the laser irradiated onto the projection surface in the optical system of (a).

[0040] Figure 6 (a) is a diagram (1) showing an optical system with a changed incident angle of the laser towards the scanning section. Figure 6 (b) is an evaluation in Figure 6Simulation results of laser light illuminating the projection surface in the optical system of (a).

[0041] Figure 7 (a) is a diagram (2) showing an optical system with a changed incident angle of the laser towards the scanning section. Figure 7 (b) is an evaluation in Figure 7 Simulation results of laser light illuminating the projection surface in the optical system of (a).

[0042] Figure 8 This is a diagram illustrating the image projection device of Embodiment 1.

[0043] Figure 9 This is a diagram showing an example of the dimensions of the image projection device of Embodiment 1.

[0044] Figure 10 (a) is a diagram (1) showing the simulated optical system. Figure 10 (b) is an evaluation in Figure 10 Simulation results of laser light illuminating the projection surface in the optical system of (a).

[0045] Figure 11 (a) is a diagram (2) showing the simulated optical system. Figure 11 (b) is an evaluation in Figure 11 Simulation results of laser light illuminating the projection surface in the optical system of (a).

[0046] Figure 12 This is a diagram showing the state in which the image projection device of Embodiment 1 is installed on an eyeglass frame.

[0047] Figure 13 This is a diagram illustrating the image projection device of Embodiment 2.

[0048] Figure 14 This is a diagram showing the situation in Embodiment 2 where the user observes the outside world through the light guide component.

[0049] Figure 15 This is a diagram showing the image projection device of Embodiment 3.

[0050] Figure 16 This is a graph showing the relationship between reflectance Rc and the ratio of light intensity Pcr / Pct.

[0051] Figure 17 (a) is a graph showing the relationship between reflectance Rc and the ratio of light intensity Pcr / Pi. Figure 17 (b) is a graph showing the relationship between reflectance Rc and transmittance Tar. Detailed Implementation

[0052] First, a comparative example of the optical system used in the image projection device will be explained.

[0053] [Comparative Example 1]

[0054] Figure 1 (a) is a diagram showing the optical system 500 of Comparative Example 1. Figure 1 As shown in (a), the optical system 500 of Comparative Example 1 includes a light source 110, a scanning unit 112, a lens 114, a reflector 116, a reflector 120, a projection lens 122, and a lens 124. The light source 110 emits a laser 140. The lens 114 converts the laser 140 emitted from the light source 110 from diffused light into focused light. The reflector 116 is a plane mirror that reflects the laser 140 that has passed through the lens 114 toward the scanning unit 112. The scanning unit 112 scans the incident laser 140 in two dimensions. Through the two-dimensional scanning performed by the scanning unit 112, multiple lasers 140 emitted from the scanning unit 112 at different times are incident on the reflector 120. The reflector 120 is a concave mirror having a reflective surface composed of curved surfaces.

[0055] Multiple lasers 140 being scanned are incident on a reflector 120 as diffused light, and are transformed into approximately parallel light by the reflector 120. The multiple lasers 140 that are scanned and reflected by the reflector 120 converge at a convergence point 160 near the projection mirror 122. A lens 124 is disposed at the convergence point 160. The multiple lasers 140 are transformed from approximately parallel light to converged light by the lens 124, and after being focused near the projection mirror 122, they become diffused light and are incident on the projection mirror 122. The projection mirror 122 is a concave mirror with a reflective surface composed of curved surfaces, and has a shape approximately the same as that of the reflector 120, with a radius of curvature approximately the same as that of the reflector 120.

[0056] Multiple lasers 140 are transformed from diffused light into approximately parallel light by projection mirror 122. After being reflected by projection mirror 122, the multiple lasers 140 converge at convergence point 162 and then illuminate projection surface 164.

[0057] When the optical system 500 is used as an image projection device, the convergence point 162 is located in the user's eye (e.g., near the pupil), and the laser 140 is converted from approximately parallel light to convergent light by the lens and focused near the retina.

[0058] The scanning angle of the scanning unit 112 towards the laser 140 is approximately the same as the convergence angle of the multiple lasers 140 converging towards the convergence point 162. Furthermore, the optical path length of the laser 140 between the scanning unit 112 and the reflector 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 reflector 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 are approximately conjugately equal.

[0059] Figure 1 (b) is in Figure 1 The simulation results evaluate the laser 140 irradiating the projection surface 164 in the optical system 500 of (a). The simulation was conducted under the condition that multiple lasers 140 emitted from the scanning unit 112 are each approximately circular in shape and generally rectangular and evenly distributed (the same applies to the simulations below). Figure 1 As shown in (b), the scanning section 112 and the convergence point 162 are approximately equal in number and conjugate, so the multiple lasers 140 on the projection surface 164 are approximately circular in shape and are distributed approximately evenly in a rectangular shape.

[0060] Here, the reason for configuring lens 124 at convergence point 160 will be explained. Lens 124 transforms laser 140 from approximately parallel light into convergent light. The laser 140, transformed into convergent light by lens 124, becomes diffuse light after being focused near the projection mirror 122 and then enters the projection mirror 122. The projection mirror 122 has a positive focusing capability that converges multiple lasers 140 to convergence point 162. Therefore, by configuring lens 124 with an appropriate focal length at convergence point 160 and setting the NA (numerical aperture) of laser 140 when it enters the projection mirror 122 to an appropriate size, the laser 140 reflected by the projection mirror 122 can be made to be approximately parallel light.

[0061] Figure 2 of (a) and Figure 2 (b) is a simulation result evaluating the laser 140 irradiating the projection surface 164 when the focal length of the lens 124 located at the convergence point 160 is different. Figure 2 (a) is the simulation result under the condition that the focal length of lens 124 is unsuitable. Figure 2 (b) is the simulation result under suitable conditions. For example... Figure 2As shown in (a), when the focal length of lens 124 is unsuitable, the sizes of the plurality of lasers 140 on projection surface 164 deviate. Therefore, when the focal length of lens 124 is unsuitable, the plurality of lasers 140 reflected by projection mirror 122 include lasers 140 that are not approximately parallel. On the other hand, as... Figure 2 As shown in (b), when the focal length of lens 124 is appropriate, the multiple lasers 140 on projection surface 164 are approximately uniform in size. Therefore, when the focal length of lens 124 is appropriate, the multiple lasers 140 reflected by projection mirror 122 all become approximately parallel beams.

[0062] Thus, by configuring a lens 124 at the convergence point 160 to transform the laser 140 from approximately parallel light into converging light, and ensuring that the focal length of the lens 124 is appropriate, the NA (aperture point) when the laser 140 is incident on the projection lens 122 is of an appropriate size. This allows the multiple lasers 140 reflected by the projection lens 122 to become approximately parallel light. Therefore, when the optical system 500 is used in an image projection device, the lens can transform the multiple lasers 140 from approximately parallel light into converging light, focusing them near the retina, thus providing the user with a high-quality image. Furthermore, since the convergence point 160 is the point where the multiple lasers 140 converge, by configuring the lens 124 at the convergence point 160, the degree of convergence of the multiple lasers 140 can be easily made appropriate.

[0063] [Comparative Example 2]

[0064] In order to ensure the field of view of the image projected onto the user's retina, it is desirable to increase the shape of the projection mirror positioned in front of the user's eyes. Figure 3 (a) is a diagram showing the optical system 600 of Comparative Example 2. Figure 3As shown in (a), the optical system 600 of Comparative Example 2 is provided with a projection mirror 122a, which has a larger radius of curvature than the reflecting mirror 120, instead of the projection mirror 122. Therefore, the optical path length of the laser 140 between the scanning unit 112 and the reflecting mirror 120 is different from the optical path length of the laser 140 between the projection mirror 122a and the convergence point 162. The optical path length of the laser 140 between the reflecting mirror 120 and the convergence point 160 is different from the optical path length of the laser 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 140 between the reflecting mirror 120 and the convergence point 160 to the optical path length of the laser 140 between the scanning unit 112 and the reflecting mirror 120, and the ratio of the optical path length of the laser 140 between the convergence point 160 and the projection mirror 122a to the optical path length of the laser 140 between the projection mirror 122a and the convergence point 162, are approximately the same. Therefore, the optical system 600 is arranged in a similar shape with approximately equal multiples, and the scanning angle of the scanning unit 112 to the laser 140 is approximately the same as the convergence angle of the multiple lasers 140 converging towards the convergence point 162.

[0065] The similarity ratio of the optical system 600 can also be determined based on the distance between the projection lens 122a and the user's eyes, the shape of the user's face, and / or the space on the side of the user's face.

[0066] Figure 3 (b) is in Figure 3 The simulation results evaluate the laser 140 irradiated onto the projection surface 164 in the optical system 600 of (a). For example... Figure 3 As shown in (b), the optical system 600 has a similar shape layout that is approximately equal in size. Therefore, the multiple lasers 140 on the projection surface 164 are approximately circular in shape and are distributed approximately evenly in a rectangular shape as a whole.

[0067] When the optical system 600 of Comparative Example 2 is used in an image projection device, the optical system 600 is sometimes mounted on an eyeglass frame. Figure 4 This diagram shows the optical system 600 of Comparative Example 2 mounted on the eyeglass frame 190. Additionally, in Figure 4 In the process, the path of the laser 140 emitted from the light source 110 until it enters the scanning unit 112 is... Figure 3 The (a) is different. For example, Figure 4As shown, the projection lens 122a is positioned in front of the user's eyes, and therefore near the frame 194 of the eyeglass frame 190. Thus, the reflector 120 and lens 124 are positioned near the user's face, and the laser 140 passes through this area. Furthermore, to protect the reflector 120, projection lens 122a, and lens 124, as well as the laser 140, they are housed within a housing 196, which is mounted on the temples 192 and frame 194 of the eyeglass frame 190. Because the reflector 120 and lens 124 are positioned near the user's face, the gap between the housing 196 and the user's face becomes smaller. For example, the distance between the eye 70 and the housing 196 becomes shorter, causing interference between the housing 196 and the eyelashes, which may sometimes degrade the quality of the image projected onto the retina 72. Additionally, because the gap between the housing 196 and the user's face is smaller, interference between the housing 196 and the user's face may occur depending on the shape of the user's face. In addition, the front-to-back dimensions of the housing 196 cannot be completely contained within the gap between a typical eyeglass frame and the face, necessitating a design that extends forward.

[0068] [Comparative Example 3]

[0069] Next, the optical system 700 of Comparative Example 3, which increases the field of view of the image compared to the optical system 600 of Comparative Example 2, will be described. Figure 5 Figure (a) is a diagram showing the optical system 700 of Comparative Example 3. The optical system 700 of Comparative Example 3 is as follows... Figure 5 As shown in (a), in order to increase the field of view of the image, the position of the convergence point 162 is made closer to the projection lens 122a compared to the optical system 600 of Comparative Example 2.

[0070] In the optical system 700 of Comparative Example 3, compared to the optical system 600 of Comparative Example 2, the position of the convergence point 162 is closer to the projection mirror 122a, therefore... Figure 4 It is evident that the gap between the housing 196 and the user's face becomes even smaller. Therefore, it is more likely to cause image quality degradation due to interference between the housing 196 and the eyelashes, and interference between the housing 196 and the user's face.

[0071] Figure 5 (b) is in Figure 5 The simulation results evaluate the laser 140 irradiated onto the projection surface 164 in the optical system 700 of (a). For example... Figure 5As shown in (b), the overall shape of the multiple lasers 140 on the projection surface 164 becomes approximately trapezoidal, resulting in trapezoidal distortion. The reason for this trapezoidal distortion is believed to be that, by bringing the convergence point 162 close to the projection mirror 122a, it deviates from a roughly equal-sized similar shape arrangement. Specifically, it is believed that the light power received from the projection mirror 122a by the lasers 140 incident from the tilted direction is not canceled out by the light power received from the reflecting mirror 120 by the lasers 140 reflected in the tilted direction, thus producing trapezoidal distortion.

[0072] In order to eliminate Figure 5 The trapezoidal distortion shown in (b) can be suppressed by performing a pre-processing that causes the projected image to produce the opposite trapezoidal distortion, thereby canceling out the pre-generated distortion with the distortion generated by the optical system 700. However, in addition to this, there is also a method to suppress trapezoidal distortion by adjusting the incident angle of the laser 140 toward the scanning unit 112.

[0073] Figure 6 (a) and Figure 7 Figure (a) shows the optical systems 710 and 720 with altered incident angles of laser 140 toward scanning unit 112. Figure 6 As shown in (a), in the optical system 710, the laser 140 is obliquely incident on the scanning section 112 from a position opposite to the projection mirror 122a relative to the reflector 120. Figure 7 As shown in (a), in the optical system 720, the laser 140 is incident obliquely onto the scanning unit 112 from a position on the same side as the projection mirror 122a relative to the reflector 120.

[0074] Figure 6 (b) and Figure 7 (b) is in Figure 6 The optical system 710 of (a) and Figure 7 The simulation results evaluate the laser 140 irradiated onto the projection surface 164 in the optical system 720 of (a). For example... Figure 6 As shown in (b), in optical system 710, with Figure 5 Compared to the simulation results of the optical system 700 shown in (b), the trapezoidal distortion is worsened. The reason for this worsening of trapezoidal distortion in the optical system 710 is as follows: In the optical system 710, the direction in which the laser 140 travels toward the scanning unit 112 is approximately the same as the direction in which the laser 140 reflected by the mirror 120 travels toward the projection mirror 122a. Therefore, it is believed that the trapezoidal distortion caused by the laser 140 being incident on the projection mirror 122a from an inclined direction is consistent with the trapezoidal distortion caused by the laser 140 being incident on the scanning unit 112 from approximately the same inclined direction, thus worsening the trapezoidal distortion.

[0075] On the other hand, such as Figure 7 As shown in (b), in optical system 720, with Figure 5 Compared to the simulation results of the optical system 700 shown in (b), trapezoidal distortion is improved. The improvement in trapezoidal distortion in the optical system 720 is attributed to the following reason: In the optical system 720, the direction in which the laser 140 travels toward the scanning unit 112 is different from the direction in which the laser 140 reflected by the mirror 120 travels toward the projection mirror 122a (the directions intersect). Therefore, it is believed that the trapezoidal distortion caused by the laser 140 incident on the projection mirror 122a from an oblique direction is reduced because the laser 140 is incident on the scanning unit 112 from a different oblique direction, thus improving the trapezoidal distortion.

[0076] In this way, by directing the laser 140 into the scanning section 112 from a direction different from the direction in which the laser 140 travels toward the projection mirror 122a after being reflected by the mirror 120, trapezoidal distortion can be improved.

[0077] like Figure 4 As shown, when the optical systems of Comparative Examples 2 and 3 are used in an image projection device, it is difficult to ensure a sufficient gap between the image projection device and the user's face. Furthermore, since the image projection device also protrudes forward, a dedicated frame is required, which detracts from the design. Therefore, examples of image projection devices that can ensure a sufficient gap between the device and the user's face and reduce the amount of forward protrusion of the image projection device are shown below.

[0078] Example 1

[0079] Figure 8 This is a diagram illustrating the image projection device 100 of Embodiment 1. Figure 8 As shown, the image projection device 100 includes a light source 10, a scanning unit 12, a lens 14, a reflector 16, a reflector 20, a lens 24, a light guide component 30, a control unit 50, and an image input unit 52. The image input unit 52 inputs image data from a camera and / or video recording device (not shown). Based on the input image data, the control unit 50 controls the emission of laser light 40 from the light source 10. Therefore, the light source 10 converts image data into laser light 40 as image rays. Furthermore, the control unit 50 also controls the driving of the scanning unit 12.

[0080] Under the control of the control unit 50, the light source 10 emits visible laser light, such as red laser (wavelength: approximately 610nm to 660nm), green laser (wavelength: approximately 515nm to 540nm), and blue laser (wavelength: approximately 440nm to 480nm). For example, a light source 10 emitting red, green, and blue laser light can be a light source integrating RGB (red, green, and blue) laser diode chips and a three-color synthesizer. Alternatively, the light source 10 can also emit laser light of a single wavelength.

[0081] The control unit 50 is, for example, a processor such as a CPU (Central Processing Unit). If the camera is positioned appropriately so that it faces the user's line of sight, the image captured by the camera in that line of sight can be projected onto the retina 72. Alternatively, images input from a recording device or the like can be projected, or the control unit 50 can overlay the camera image with an image from a recording device or the like to project a so-called virtual reality (AR) image.

[0082] The laser 40 emitted from the light source 10 passes through the lens 14. The lens 14 is a focusing lens that converts the laser 40 from diffused light into focused light. The laser 40 that has passed through the lens 14 is reflected by the reflector 16 towards the scanning unit 12 and enters the scanning unit 12 as focused light. The reflector 16 is a plane mirror. The lens 14 is disposed between the light source 10 and the scanning unit 12 in order to make the laser 40 reflected by the reflector 20 approximately parallel light.

[0083] The scanning unit 12 (scanner) scans the incident laser 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. Alternatively, the scanning unit 12 can be made of potassium tantalate-niobate (KTN) or other materials. Multiple lasers 40, scanned in two dimensions by the scanning unit 12 and emitted from it at different times, are incident on the reflecting mirror 20. Each laser 40 is focused near the reflecting mirror 20 and becomes diffused light before entering the reflecting mirror 20. The reflecting mirror 20 is a concave mirror with a reflective surface composed of freeform surfaces or similar curved surfaces, possessing positive focusing capability. Therefore, each laser 40 is reflected by the reflecting mirror 20, thereby transforming diffused light into approximately parallel light.

[0084] Multiple lasers 40 reflected by mirror 20 converge at a convergence point 60 near the light guide component 30. A lens 24 is disposed at the convergence point 60. Lens 24 is a focusing lens that transforms the multiple lasers 40 from approximately parallel light into converged light. Figure 2 (a) and Figure 2For the same reason explained in (b), in order to make the multiple lasers 40 emitted from the light guide 30 toward the user's eye 70 approximately parallel, the lens 24 is positioned at the convergence point 60. The multiple lasers 40 passing through the lens 24 are incident on the light guide 30.

[0085] The light guide component 30 is formed of a glass material such as cyclic olefin polymer (COP) resin or acrylic resin. The laser 40 passes through the interior of the light guide component 30. The light guide component 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 onto the glass material. The laser 40 is reflected within the light guide component 30 in the order of reflective surfaces 32, 34, and 36, and is emitted outward from the light guide component 30. Reflective surfaces 32 and 34 are generally flat surfaces and are arranged approximately parallel to each other. For example, reflective surfaces 32 and 34 are approximately parallel to the user's face. On the other hand, reflective surface 36 is a concave surface such as a free-form surface. "Generally flat surface" refers to a flat surface that does not impart a focusing ability to the laser 40. "Generally parallel" means a slope of ±5° or less, which can be ±3° or less, or ±1° or less.

[0086] Multiple lasers 40 incident on the light guide component 30 travel toward the reflective surface 32 while converging. The multiple lasers 40 converge near the reflective surface 32. For example, the laser 40a corresponding to the center of the image projected onto the retina (or the laser when the deflection angle of the scanning unit 12 is 0°) converges on the reflective surface 32. The multiple lasers 40 reflected by the reflective surface 32 travel toward the reflective surface 34. For example, all the multiple lasers 40 converge near the reflective surface 34 and become diffused light before incident on the reflective surface 34. The multiple lasers 40 reflected by the reflective surface 34 are incident on the reflective surface 36 as diffused light.

[0087] The reflective surface 36 is concave, thus possessing positive light-focusing capability. Therefore, the multiple lasers 40 reflected by the reflective surface 36 are transformed from diffused light into approximately parallel light, and the multiple lasers 40 converge at a convergence point 62 within the user's eye 70. The convergence point 62 is, for example, located near the pupil 74. Since the lasers 40 traveling towards the eye 70 are approximately parallel light, they are transformed from approximately parallel light into convergent light by the lens 76 and focused near the retina 72. This enables user A to visually recognize image A.

[0088] In order to increase the field of view of the image projected onto the retina 72, the curvature of the reflective surface 36 is set in such a way that the convergence angle α2 of the multiple lasers 40 converging towards the convergence point 62 is larger than the scanning angle α1 of the scanning unit 12.

[0089] The reflecting surface 34 has a region 34a that reflects the laser 40 reflected by the reflecting surface 32 toward the reflecting surface 36 and a region 34b that allows the laser 40 reflected by the reflecting surface 36 to pass through, with regions 34a and 34b partially overlapping. In this overlapping region 34c, both the function of reflecting the laser 40 and the function of allowing it to pass through are required. The angle of incidence of the laser 40 reflected by the reflecting surface 32 onto the reflecting surface 34 is greater than the angle of incidence of the laser 40 reflected by the reflecting surface 36 onto the reflecting surface 34. Therefore, at least in region 34c of the reflecting surface 34, there is an angle dependence such that the laser 40 with a large angle of incidence is mainly reflected, and the laser 40 with a small angle of incidence is mainly transmitted, thereby achieving both the reflection of the laser 40 reflected by the reflecting surface 32 and the transmission of the laser 40 reflected by the reflecting surface 36. In addition, the laser 40 reflected by the reflective surface 36 can be projected onto the retina 72. Even if the laser 40 reflected by the reflective surface 32 passes through the reflective surface 34, it will not have any effect. Therefore, by using a semi-reflective mirror on the reflective surface 34, it is possible to both reflect the laser 40 reflected by the reflective surface 32 and allow the laser 40 reflected by the reflective surface 36 to pass through.

[0090] Here, an example of the dimensions of the image projection device 100 will be described. Figure 9 This is a diagram showing an example of the dimensions of the image projection device 100 of Embodiment 1. Furthermore, the dimensional examples shown below assume that the refractive index of the light guide member 30 is approximately 1.5 to 1.55. Additionally, each dimension represents the length along the trajectory of the axis of the laser 40a corresponding to the center of the image projected onto the retina 72. Figure 9As shown, the length L1 between the scanning unit 12 and the reflector 20 is 6mm to 9mm, and 7.5mm is an example. The length L2 between the reflector 20 and the incident surface 31a of the light guide member 30 is 10.7mm to 16mm, and 13.4mm is an example. The length L3 of the lens 24 is 2.4mm to 3.6mm, and 3mm is an example. The length L4 between the incident surface 31a of the light guide member 30 and the reflecting surface 32 is 10mm to 14.8mm, and 12.4mm is an example. The length L5 between the reflecting surfaces 32 and 34 is 6mm to 9mm, and 7.6mm is an example. The length L6 between the reflecting surfaces 34 and 36 is 4.3mm to 6.5mm, and 5.4mm is an example. The length L7 between the reflecting surface 36 and the exit surface 31b of the light guide member 30 is 2.8mm to 4.2mm, and 3.5mm is an example. The length L8 from the emission surface 31b of the light guide component 30 to the cornea 78 of the eye 70 is 6.7 mm to 10 mm, and is 8.4 mm in one example. The incident angle θ1 of the laser 40a towards the reflector 20 is 20° to 30°, and is 25° in one example. The incident angles θ2 of the laser 40a towards the reflecting surface 32 and θ3 towards the reflecting surface 34 are 40° to 60°, and are 50° in one example. The incident angle θ4 of the laser 40a towards the reflecting surface 36 is 20° to 30°, and is 25° in one example. Furthermore, regarding... Figure 9 If the dimensions of L2 to L7 in the design are constant, the result will be the same. This can also be used to make fine adjustments to the dimensions.

[0091] Thus, for example, the lengths L4, L5, L6, and L7 within the light guide component 30 decrease sequentially. For instance, the incident angles θ1 of the laser 40a toward the reflector 20 and θ4 toward the reflector 36 are approximately the same, and the incident angles θ2 toward the reflector 32 and θ3 toward the reflector 34 are approximately the same, with incident angles θ2 and θ3 being approximately twice the size of incident angles θ1 and θ4. Therefore, a high-quality image can be projected onto the retina 72. The phrases "approximately the same size" and "approximately twice the size" refer to the same degree of projection of a high-quality image onto the retina 72 as, and twice that size.

[0092] like Figure 8As shown, the laser 40a, corresponding to the center of the image projected onto the retina 72, travels towards the reflector 20 after being reflected by the scanning unit 12, and is approximately parallel to the direction in which it travels towards the eye 70 after being reflected by the reflector 36 of the light guide member 30. The reflector 34 is arranged approximately orthogonally to the laser 40a traveling towards the eye 70 after being reflected by the reflector 36 of the light guide member 30. The reflector 32 is arranged approximately parallel to the reflector 34. With this structure, a high-quality image can be projected onto the retina 72. "Approximately parallel" means the slope is ±5° or less, which can be ±3° or less, or ±1° or less. "Approximately orthogonal" means the intersection angle is 90° ±5°, which can be 90° ±3° or 90° ±1°.

[0093] Furthermore, the laser 40a, corresponding to the center of the image projected onto the retina 72, is incident approximately perpendicularly onto the incident surface 31a of the light guide member 30. "Approximately perpendicular" means approximately 90° ± 5°, but can also be 90° ± 3° or 90° ± 1°. Figure 10 (a) to Figure 11 (b) Explains the effect. Figure 10 (a) and Figure 11 (a) is a diagram showing the simulated optical systems 800 and 810. Figure 10 (b) and Figure 11 (b) is an evaluation of the situation in Figure 10 The optical system 800 of (a) and Figure 11 Simulation results of laser 140 irradiating the projection surface 164 in the optical system 810 of (a).

[0094] like Figure 10 (a) and Figure 11 As shown in (a), in the optical systems 800 and 810 used for simulation, multiple lasers 140 are reflected by mirror 120 and converge at convergence point 160 before being incident from incident surface 131a to light guide component 130. Light guide component 130 has a reflective surface 136, and the multiple lasers 140 are reflected by reflective surface 136 and converge at convergence point 162 before being projected onto projection surface 164. Figure 10 In the optical system 800 of (a), when the laser 140a has a deflection angle of 0° relative to the scanning unit 112, the incident surface 131a of the light guide member 130 is tilted to one side. Figure 11 In the optical system 810 of (a), when the laser 140a is deflected at 0° relative to the scanning unit 112, the incident surface 131a of the light guide member 130 is tilted to the other side.

[0095] like Figure 10 (b) and Figure 11As shown in (b), when the laser 140a is incident on the light guide member 130 at an angle, the result is that the multiple lasers 140 that are irradiated onto the projection surface 164 produce deviations and angles.

[0096] According to the simulation results, in the image projection device 100 of Embodiment 1, in order to project a high-quality image onto the retina 72, it is preferable that the laser 40a is incident approximately perpendicularly onto the incident surface 31a of the light guide component 30.

[0097] Figure 12 This diagram shows the image projection device 100 of Embodiment 1 mounted on the eyeglass frame 90. (As shown) Figure 12 As shown, the spectacle frame 90 has temples 92 and a frame 94. The scanning unit 12 and the reflector 20 are mounted on the spectacle frame 90 near the temples 92. The light guide component 30 is mounted on the spectacle frame 90 near the frame 94. The light source 10, scanning unit 12, lens 14, reflector 16, reflector 20, and lens 24 are housed within a housing 96 that protects them and the laser 40. By mounting the housing 96 to the spectacle frame 90, the optical components within the housing 96 are also mounted on the spectacle frame. The light guide component 30 is formed of glass, and the laser 40 passes through the interior of the light guide component 30; therefore, most of the light guide component 30 is not located within the housing 96. "Most of the light guide component 30 is not located within the housing 96" means that more than 80% of the light guide component 30 is not located within the housing 96; it could be more than 85% or more, or even more than 90%.

[0098] The laser 40 travels within the light guide component 30 while being reflected by the reflective surfaces 32-36, thereby allowing the reflector 20 and lens 24 to be positioned away from the user's face. Furthermore, the housing 96, which houses the reflector 20 and lens 24, is also positioned away from the user's face because these components are located away from the user's face. Therefore, the gap between the housing 96 and the user's face can be sufficiently ensured, suppressing interference between them.

[0099] Since the light guide component 30 is made of glass, most of it can be left unretained within the housing 96. To increase the field of view of the image projected onto the retina 72, the distance between the eye 70 and the light guide component 30 ( Figure 9 The length L8 in the middle is shortened, but most of the light guide component 30 is not housed in the housing 96. Therefore, even if the field of view of the image is increased, the distance between the eye 70 and the light guide component 30 can be maintained at a length (e.g., more than 8 mm) that makes it difficult for the eyelashes to interfere with the light guide component 30.

[0100] Furthermore, the light guide component 30, made of glass, is positioned in front of the eye. The laser 40 is reflected multiple times within the light guide component 30 before reaching the retina 72. Therefore, the light guide component 30 is shaped to extend along the user's face. Thus, compared to cases like Comparative Example 2, where the laser is reflected by a projection mirror positioned in front of the eye before reaching the retina 72, the forward protrusion of the image projection device 100 in front of the eye is reduced. Moreover, since the laser 40 travels within the light guide component 30, the housing 96 does not need to cover the light guide component 30, further reducing the forward protrusion of the image projection device 100 in front of the eye. This improves design flexibility.

[0101] As explained above, according to this embodiment 1, such as Figure 8 As shown, multiple laser beams 40 (image rays) scanned by the scanning unit 12 converge at a convergence point 60 (second convergence point) near the light guide member 30 via a reflector 20 (first optical component) and then enter the light guide member 30. The light guide member 30 is formed of a glass material through which the laser beams 40 pass, causing the multiple laser beams 40 reflected by multiple reflective surfaces 32, 34, and 36 to converge at the convergence point 62 (first convergence point) within the eye 70 and then illuminate the retina 72. A lens 24 (second optical component) is provided at the convergence point 60 to diffuse the laser beams 40 onto the reflective surface 36 at the rear end of the light guide member 30. By providing the lens 24 at the convergence point 60, the aperture (NA) of the laser beams 40 when they enter the reflective surface 36 at the rear end of the light guide member 30 can be appropriately sized, and the multiple laser beams 40 reflected by the reflective surface 36 can be made approximately parallel. Therefore, a high-quality image can be projected. By providing a light guide component 30, formed of glass material through which the laser 40 passes internally, at the rear end of such a lens 24, such as... Figure 12 As shown, most of the light guide component 30 can be left unretained in the housing 96, thus ensuring sufficient clearance between the image projection device 100 and the user's face.

[0102] Additionally, in this embodiment 1, as Figure 12 As shown, the scanning unit 12 and the reflector 20 are mounted near the temple 92 of the eyeglass frame 90, and the light guide member 30 is mounted near the frame 94 of the eyeglass frame 90. Furthermore, the light guide member 30 has a shape that extends from in front of the user's eye 70 towards the temple 92 of the eyeglass frame 90. Therefore, the scanning unit 12, the reflector 20, the lens 24, and the light guide member 30 can be arranged along the contour of the user's face. Thus, sufficient clearance can be ensured between the image projection device 100 and the user's face. Additionally, the image projection device 100 can be miniaturized.

[0103] Additionally, in this embodiment 1, as Figure 12As shown, the light guide component 30 has an odd number of reflective surfaces 32, 34, and 36. Multiple lasers 40, reflected by the mirror 20 and traveling obliquely forward, are incident on the light guide component 30. Thus, the lasers 40 travel from the temple 92 side of the eyeglass frame 90 toward the eye 70 inside the light guide component 30, allowing the scanning unit 12, mirror 20, lens 24, and light guide component 30 to be arranged along the contour of the user's face.

[0104] Additionally, in this embodiment 1, as Figure 8 As shown, the last reflective surface 36 of the plurality of reflective surfaces 32, 34, and 36 of the light guide component 30 is a concave curved surface, while the remaining reflective surfaces 32 and 34 are generally flat surfaces. This allows the laser 40 to travel from the temple 92 side of the eyeglass frame 90 towards the eye 70 within the light guide component 30, and allows the scanning unit 12, reflector 20, lens 24, and light guide component 30 to be arranged along the contour of the user's face. Furthermore, it is preferable that reflective surfaces 32 and 34 are generally parallel to each other.

[0105] Additionally, in this embodiment 1, as Figure 8 As shown, the preceding reflective surface 34 (first reflective surface) of the final reflective surface 36 has a region 34c in which both the laser 40 reflected by its preceding reflective surface 32 (second reflective surface) and the laser 40 reflected by the final reflective surface 36 are incident. The reflective surface 34 reflects the laser 40 reflected by the reflective surface 32 towards the reflective surface 36 in this region 34c, and allows the laser 40 reflected by the reflective surface 36 to pass through. Thus, multiple lasers 40 can be converged at the convergence point 62 and irradiate the retina 72. Furthermore, the light guide component 30 can be miniaturized.

[0106] Furthermore, in this embodiment 1, the reflective surface 34 is approximately orthogonal to the optical axis of the laser 40a (center image ray) corresponding to the center of the image after being reflected by the reflective surface 36. Thus, even if the multiple lasers 40 reflected by the reflective surface 36 are refracted when emitted from the light guide member 30, the multiple lasers 40 can be converged at the convergence point 62.

[0107] Furthermore, in this embodiment 1, the convergence angle α2 of the multiple lasers 40 converging at the convergence point 62 is larger than the scanning angle α1 of the scanning unit 12 towards the multiple lasers 40. This increases the field of view of the image projected onto the retina 72. Additionally, most of the light guide member 30 may not be housed within the housing 96, so even if the convergence point 62 is brought close to the light guide member 30 to increase the image viewing angle, the gap between the image projection device 100 and the user's face can be adequately ensured. Furthermore, the convergence angle α2 may be greater than or equal to the scanning angle α1.

[0108] Additionally, in this embodiment 1, as Figure 12As shown, the laser 40 travels diagonally forward from the scanning section 12, which is closer to the user's face than the side of the eyeglass frame 90 near the temple 92, and then travels backward from the scanning section 12 before being reflected diagonally forward by the mirror 20, and finally enters the light guide member 30 near the frame 94 of the eyeglass frame 90. Thus, according to... Figure 7 of (a) and Figure 7 The same reasoning explained in (b) enables the projection of a high-quality image onto the retina 72 that suppresses distortion.

[0109] Example 2

[0110] Figure 13 This is a diagram illustrating the image projection device 200 of Embodiment 2. In the image projection device 200 of Embodiment 2, as... Figure 13 As shown, the light guide component 30a includes: a main body 38 that travels while being reflected by reflective surfaces 32-36 so that multiple lasers 40 incident on the incident surface 31a can irradiate the user's eye 70; and a cover 39 that is attached to the main body 38 in such a way that it covers the reflective surfaces 32 and 36 from the outside. The main body 38 and the cover 39 are formed of glass material with approximately the same refractive index, for example, of the same glass material. The emission surface 31b of the multiple lasers 40 reflected by the reflective surface 36 is flatter than the reflective surface 36 when they exit from the main body 38. The surface 39a of the cover 39, located opposite to the emission surface 31b of the main body 38 relative to the reflective surface 36, is flatter than the reflective surface 36. The surface 39a of the cover 39 and the emission surface 31b of the main body 38 are, for example, approximately parallel and approximately flat surfaces to each other. In addition, all reflective surfaces 32-36 are semi-reflective mirrors. Other structures are the same as in Embodiment 1, so descriptions are omitted.

[0111] Figure 14 This diagram illustrates the user's observation of the outside world via the light guide component 30a in Embodiment 2. Figure 14 As shown, the emission surface 31b of the main body 38, the reflective surface 36, and the surface 39a of the cover 39 are located in front of the user's eye 70. The refractive indices of the main body 38 and the cover 39 are approximately the same, and the surface 39a of the cover 39 and the emission surface 31b of the main body 38 are highly flat surfaces. Therefore, the user can visually recognize the outside world by suppressing the sense of incongruity through the reflective surface 36, which acts as a semi-reflective mirror, just like the line of sight 79.

[0112] According to Embodiment 2, the light guide component 30a includes: a main body 38 through which multiple laser beams 40, repeatedly reflected by multiple reflective surfaces 32-36, irradiate the user's retina 72; and a cover 39 covering the final reflective surface 36, having a refractive index approximately the same as that of the main body 38. The reflective surface 36 is a semi-reflective mirror, and the surface 39a of the cover 39 and the emission surface 31b of the main body 38 are flatter than the reflective surface 36. Thus, as... Figure 14 As shown, users can suppress the sense of incongruity and visually recognize the outside world. Therefore, it is possible to handle augmented reality (AR) that overlays virtual visual information onto a real landscape. The fact that the refractive indices of the main body 38 and the cover 39 are approximately the same means that the degree to which users can suppress the sense of incongruity and visually recognize the outside world is the same, and that the difference in refractive indices is less than 0.05.

[0113] Furthermore, in this embodiment 2, the surface 39a of the cover portion 39 and the emission surface 31b of the main body portion 38 are substantially parallel to each other and are substantially flat. This allows the user to further suppress any sense of unease while visually recognizing the outside world. It should be noted that, in order to correct the user's vision, the surface 39a of the cover portion 39 can also be a concave or convex surface that conforms to the degree of correction. Therefore, the statement that the surface 39a of the cover portion 39 is substantially flat, including the case where it is curved under the degree of vision correction, means that it is flat to the extent that the user can suppress any sense of unease while visually recognizing the outside world. The statement that the surface 39a of the cover portion 39 and the emission surface 31b of the main body portion 38 are substantially parallel means that even if the surface 39a of the cover portion 39 is a curved surface for the degree of vision correction, it is parallel to the extent that the user can suppress any sense of unease while visually recognizing the outside world.

[0114] Furthermore, as in Embodiment 2 above, it is preferable that the cover 39 covers both the reflective surfaces 32 and 36. This reduces the unsightly appearance at the boundary between the reflective surfaces 32 and 36 when the user observes the outside world.

[0115] Furthermore, in Embodiment 2 described above, the main body 38 can be formed integrally by one-piece molding, or it can be formed by molding a first part 38a, which is composed of a generally flat reflective surface, and a second part 38b, which has a free-form reflective surface 36, and then bonding them together. The first part 38a and the second part 38b are bonded together after being molded using different molds, thereby improving manufacturing ease. On the other hand, forming the main body 38 integrally by one-piece molding improves mass production capability.

[0116] Example 3

[0117] Figure 15 This is a diagram illustrating the image projection device 300 of Embodiment 3. In the image projection device 300 of Embodiment 3, as... Figure 15As shown, similarly to Embodiment 2, the light guide component 30a has a main body 38 and a cover 39. Also similarly to Embodiment 2, the main body 38 has a reflective surface 34 located on the side closer to the user's eye 70, and a reflective surface 32 located on the side farther from the user's eye 70, for the multiple lasers 40 to be incident on before the final reflective surface 36. The difference from Embodiment 2 is that the cover 39 has a reflective surface 37 located opposite to the emission surface 31b of the main body 38 relative to the reflective surface 36. The reflective surface 37, like the reflective surfaces 32 and 34, is a flat surface, substantially the same as the reflective surface 32. The reflective surfaces 32, 34, 36, and 37 all reflect a portion of the incident laser 40, allowing the remainder to pass through. The multiple lasers 40 are reflected the same number of times by the multiple reflective surfaces 32, 34, 36, and 37 before illuminating the eye 70.

[0118] To achieve a thinner light guide component 30a and ensure lateral extension and / or viewing angle to suppress interference with the user's face, the number of reflections of the laser 40 within the light guide component 30a is increased. In this case, if multiple lasers 40 are to converge at the convergence point 62, a portion of the lasers 40c are incident from the eye 70 side onto the reflecting surface 36 and pass through it. After being reflected by the reflecting surface 37 of the cover portion 39, they are again incident from the opposite side (opposite side) of the eye 70 onto the reflecting surface 36, pass through it, are reflected by the reflecting surface 34, and are then reflected by the reflecting surface 36 to illuminate the eye 70. The remaining lasers 40a and 40b of the multiple lasers 40 do not pass through the reflecting surface 36 but are reflected by the reflecting surface 36 and illuminate the eye 70. Additionally, although not shown in the figure, a portion of the lasers 40a and 40b also passes through the reflecting surface 36, but since this light does not illuminate the retina 72, it can be disregarded.

[0119] To suppress brightness deviations in the image projected onto the retina 72, it is preferable to minimize the brightness difference when lasers 40a and 40b, which are reflected by the reflective surface 36 but do not pass through it, and then illuminate the eye 70, and laser 40c, which passes through the reflective surface 36 and is reflected by it, also illuminate the eye 70, are incident on the eye 70. On the other hand, it is preferable that the light intensity of lasers 40a to 40c incident on the eye 70 is sufficiently high. Furthermore, when observing the outside world via the light guide member 30a, the transmittance of the light guide member 30a is preferably around 10% to 30%. Therefore, a method for achieving these objectives is described below.

[0120] In the following description, laser light 40a to 40c is reflected a total of four times by reflecting surfaces 32, 34, and 37, and then shines on the eye 70 through a fifth reflection on the final reflecting surface 36. Furthermore, the reflectivity of each surface is specified below. For simplicity, the sum of the transmittance and reflectivity of the same surface is set to 1 (transmittance + reflectivity = 1).

[0121] Incident light quantity of laser beams 40a~40c onto incident surface 31a: Pi

[0122] Transmittance of incident surface 31a: Tp

[0123] Reflectivity of incident surface 31a: Rp (=1-Tp)

[0124] Transmittance of reflective surface 34: Ta

[0125] Reflectivity of reflective surface 34: Ra (=1-Ta)

[0126] Transmittance of reflective surface 32: Tb

[0127] Reflectivity of reflective surface 32: Rb (=1-Tb)

[0128] Transmittance of reflective surface 36: Tc

[0129] Reflectivity of reflective surface 36: Rc (=1-Tc)

[0130] Transmittance of reflective surface 37: Td

[0131] Reflectivity of reflective surface 37: Rd (=1-Td)

[0132] In this case, the amount of light Pcr when the lasers 40a and 40b, which are not transmitted through the reflective surface 36 but are reflected by the reflective surface 36, irradiate the eye 70 is: Pcr=Pi×Tp×Ta×Rb×Ra×Rb×Ra×Rc×Ta…(1)

[0133] On the other hand, the amount of light Pct when the laser 40c, which passes through the reflector 36 and is reflected by the reflector 36, irradiates the eye 70 is: Pct=Pi×Tp×Ta×Rb×Ra×Tc×Rd×Tc×Ra×Rc×Ta···(2).

[0134] For simplicity, let the transmittance Tp of the incident surface 31a be 1. In this case, equations (1) and (2) can be modified as follows.

[0135] Pcr / Pi=Ta×Rb×Ra×Rb×Ra×Rc×Ta...(3)

[0136] Pct / Pi=Ta×Rb×Ra×Tc×Rd×Tc×Ra×Rc×Ta...(4)

[0137] To suppress uneven brightness on the image projected onto the retina 72, it is preferable that equation (3) / equation (4) is close to 1. In addition, equations (3) and (4) are the ratio of the amount of light irradiated onto the eye 70 to the amount of incident light, so it is preferable to have a larger ratio.

[0138] The case where equation (3) / equation (4) is close to 1 is expressed as follows.

[0139] Pcr / Pct=Rb / (Tc×Rd×Tc)≒1...(5)

[0140] Here, reflective surface 32 and reflective surface 37 are continuous, identical surfaces, and the user observes the outside world through reflective surface 32 and reflective surface 37. Therefore, it is preferable that their reflectivities are approximately the same. Thus, Rb = Rd is set below. In this case, equation (5) is as follows.

[0141] Pcr / Pct=1 / Tc 2 ≒1...(5´)

[0142] Tc = 1 means that the reflectivity at the reflecting surface 36 is zero, and the laser beams 40a to 40c are not reflected by the reflecting surface 36 and are not projected onto the retina 72. Therefore, Tc is preferably set to a value less than 1 and is set to a value that takes into account the balance.

[0143] Here, when a user observes the outside world via the light guide component 30a for purposes such as AR (Augmented Reality), light from the outside reaches the user's eye 70 via reflective surfaces 32, 37, 36, and 34. For sunglasses, a transmittance of approximately 10% to 30% of the light from the outside is generally considered suitable. The transmittance Tar of reflective surfaces 32, 37, 36, and 34 is shown below.

[0144] Tar=Td×Tc×Ta=(1-Rd)×(1-Rc)×(1-Ra)...(6)

[0145] Based on the above, the ranges of Ra, Rb, Rc, and Rd are shown below.

[0146] [Range of Rc]

[0147] It is known that human visual sensitivity is almost incapable of discerning brightness differences of around 70% to 80%. The Tc in equation (5′) 2 It can be transformed into (1-Rc). 2 If Pcr / Pct = (1 - Rc) 2 If represented in a chart, then as follows Figure 16 As shown. According to Figure 16It can be seen that, in order to suppress the brightness difference to around 70% to 80%, the following range of Rc is preferred.

[0148] Rc≤15%

[0149] [Ra range]

[0150] As stated above, from the viewpoint of the amount of light illuminating the eye 70, it is preferable to have a larger value in equation (3). Rc in equation (3) is subject to the aforementioned constraints. Rb will be discussed later, but it is preferable to have at least Ta×Ra×Ra×Ta = (1-Ra) included in equation (3). 2 ×Ra 2 The larger case. In this case, it becomes the largest when Ra = 0.5, so it can be said that the range of Ra is preferably the following.

[0151] 45%≤Ra≤55%

[0152] [Range of Rb]

[0153] Figure 17 Figure (a) shows the relationship between Rc and Pcr / Pi when Ra in equation (3) is fixed at 50% and Rb is varied to 30%, 40%, 50%, 60%, 70%, and 80%. As mentioned above, equation (3) represents the ratio of the amount of light irradiated to the eye 70 to the amount of incident light, and therefore a larger ratio is preferred. Considering that the laser output of the light source 10 is several mW, and the amount of light irradiated to the eye 70 is attenuated to about 1 / 10000 of several mW, the ratio of the amount of light irradiated to the eye 70 to the amount of incident light is preferably about 0.1%. Therefore, according to Figure 17 (a) can be said to favor Rb, which is Rb≥50%.

[0154] Figure 17 Figure (b) shows the relationship between Rc and Tar when Ra in equation (6) is fixed at 50% and Rb is varied to 30%, 40%, 50%, 60%, 70%, and 80%. As mentioned above, a transmittance of about 10% to 30% for light from the outside is suitable. Therefore, according to... Figure 17 (b) can be said to favor Rb of 40% ≤ Rb ≤ 70%.

[0155] Therefore, according to Figure 17 (a) and Figure 17 (b) can be said that the range of Rb is preferably the following.

[0156] 50%≤Rb≤70%

[0157] Furthermore, as mentioned above, since the user observes the outside world through the reflective surfaces 32 and 37, which are continuous surfaces, it is preferable that Rb and Rd are equal. Therefore, it can be said that the range of Rd is preferably as follows.

[0158] 50%≤Rd≤70%

[0159] Therefore, it can be said that the preferred option is: The reflectivity Ra of reflecting surface 34 (first reflecting surface) ranges as follows: 45% ≤ Ra ≤ 55% The reflectivity Rb of reflective surface 32 (second reflective surface) ranges as follows: 50% ≤ Rb ≤ 70%. The reflectivity Rc range of reflective surface 36 (the last section of the reflective surface): 5% ≤ Rc ≤ 15% The reflectivity Rd range of reflective surface 37 (third reflective surface): 50% ≤ Rd ≤ 70% According to Embodiment 3, a portion of the multiple lasers 40, 40c, after passing through the reflective surface 36, re-enters the reflective surface 36 and is reflected by it to illuminate the retina 72. The remaining lasers 40a and 40b do not pass through the reflective surface 36 but are reflected by it to illuminate the retina 72. In this case, when lasers 40a to 40c are incident on the eye 70, the ratio of the brightness of laser 40c to the brightness of lasers 40a and 40b is set to 80% or more. This suppresses brightness deviations in the image projected onto the retina 72.

[0160] The reflectivity Rc of the reflecting surface 36 is set to below 15%. By setting the reflectivity Rc of the reflecting surface 36 to below 15%, such as... Figure 16 As shown, the brightness difference between the laser 40c reflected by the reflective surface 36 after passing through it and the lasers 40a and 40b reflected by the reflective surface 36 without passing through it can be suppressed to about 70%. Therefore, brightness deviation on the image projected onto the retina 72 can be suppressed. From the viewpoint of reducing the brightness difference, Rc is preferably 13% or less, more preferably 12% or less, and even more preferably 10% or less. On the other hand, if Rc becomes too small, the amount of laser 40 reflected on the reflective surface 36 will be small. If it is necessary to ensure the amount of light 40 irradiated to the eye 70, for example, the output of the light source 10 should be increased. Therefore, Rc is preferably 5% or more, more preferably 8% or more, and even more preferably 10% or more.

[0161] The reflectivity Rb of reflecting surface 32 and the reflectivity Rd of reflecting surface 37 are made approximately the same. Therefore, even when lasers 40a and 40b are not reflected by reflecting surface 37, but laser 40c is reflected by reflecting surface 37, the brightness difference in lasers 40a and 40c caused by the presence or absence of reflection from reflecting surface 37 can be minimized. "Approximately the same" means that the ratio of the reflectivity Rd of reflecting surface 37 to the reflectivity Rb of reflecting surface 32 is 95% to 105%, or it could be 98% to 102%.

[0162] The reflectivity Rb of reflective surface 32 and the reflectivity Rd of reflective surface 37 are set to be 40% or more and 70% or less. Therefore, when observing the outside world via light guide component 30a in an AR or similar application, the outside world can be observed with appropriate brightness.

[0163] In order to minimize the brightness difference among the multiple lasers 40 that illuminate the eye 70, ensure a large amount of light from the lasers 40 incident on the eye 70, and ensure visual recognition when observing the outside world through the light guide component 30a, it is preferable that the reflectivity Ra of the reflective surface 34 is 45% or more and 55% or less, the reflectivity Rb and Rd of the reflective surfaces 32 and 37 are 50% or more and 70% or less, and the reflectivity Rc of the reflective surface 36 is 5% or more and 15% or less.

[0164] Furthermore, in the above embodiments 1 and 2, as long as the reflector 20 has a positive focusing ability and optical characteristics that allow multiple lasers 40 to converge and then diffuse, it can be a combination lens or mirror, or other optical components using diffraction elements, in addition to a curved mirror.

[0165] Furthermore, in Embodiments 1 and 2 described above, lens 24 may also have the function of suppressing chromatic aberration. Additionally, lens 24 preferably employs a design that suppresses image plane curvature. Lens 24 can be any optical component, such as a mirror, diffraction element, or other optical component, as long as it allows laser 40 to be incident as diffused light onto the reflecting surface 36 of the light guide component 30.

[0166] Furthermore, in the above embodiments 1 and 2, the case of installing the image projection device 100 on the eyeglass frame 90 was described as an example. However, as long as the 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 eyeglasses. It can also be goggles, eye patches, ear hooks, helmets, or other types.

[0167] Although certain embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments, but can be varied or modified within the scope of protection of the present invention as described in the claims.

Claims

1. An image projection device, wherein, The image projection device includes: light source; The control unit generates image rays based on image data and controls the emission of the image rays from the light source; A scanning unit that scans the image light emitted from the light source in two dimensions; and The light guide component is formed of a glass material through which multiple image light rays emitted from the scanning unit at different times pass. It has multiple reflective surfaces that reflect the multiple image light rays, such that the multiple image light rays reflected by the last reflective surface of the multiple reflective surfaces converge at a point of convergence within the user's eye and then illuminate the user's retina. A portion of the multiple image rays, after passing through the reflective surface of the final segment, are incident again on the opposite side of the final reflective surface and pass through again, then reflected by the final reflective surface to illuminate the user's retina. The remaining image rays do not pass through the final reflective surface but are reflected by the final reflective surface to illuminate the user's retina. The reflectivity of the final section's reflective surface is less than 15%.

2. The image projection device according to claim 1, wherein, The plurality of reflective surfaces have: a first reflective surface located on the side closer to the user's eye; a second reflective surface located on the side farther from the user's eye, for the plurality of image rays to be incident on before reaching the final reflective surface; and a third reflective surface for the plurality of image rays to be incident on after passing through the final reflective surface. The reflectivity of the second reflective surface is approximately the same as that of the third reflective surface.

3. The image projection device according to claim 2, wherein, The reflectivity of the second reflective surface and the reflectivity of the third reflective surface are both above 40% and below 70%.

4. The image projection device according to claim 2, wherein, The reflectivity of the first reflective surface is above 45% and below 55%. The reflectivity of the second reflective surface and the reflectivity of the third reflective surface are both above 50% and below 70%. The reflectivity of the final segment's reflective surface is between 5% and 15%.

5. The image projection device according to claim 1, wherein, The multiple image rays are reflected the same number of times by the multiple reflective surfaces and then illuminate the user's retina.

Images