Detection device, gaze detection device, and image display device

Abstract

This detection device detects information relating to user's eyes. The detection device comprises: a frame that is attached to the face of a user; a light source unit that emits infrared light; a light guide plate that is disposed in front of an eye of the user, and has an emission layer for dividing and duplicating the infrared light incident from the light source unit and emitting the duplicated light from each of a plurality of emission positions; and an imaging unit that captures images of a plurality of infrared light beams emitted from the plurality of emission positions and reflected by the eye of the user and the pupil of the eye of the user. The light source unit, the light guide plate, and the imaging unit are attached to the frame.

Description

Detection device, gaze detection device, and image display device

[0001] The present disclosure relates to a detection device, a gaze detection device, and an image display device that detect information on a user's eyes.

[0002] As a detection device for detecting information on a user's eyes, Patent Document 1 describes a detection device that irradiates infrared light from infrared light sources arranged in an array toward the user's eyes and detects the positional relationship between each reflected light and the pupil of the eyes.

[0003] U.S. Patent No. 10,852,824

[0004] However, when arranging infrared light sources in an array as in Patent Document 1, the wiring for supplying power to each light source must be arranged in the illumination layer facing the user's eyes, which requires a complicated manufacturing process.

[0005] The present disclosure provides a detection device, a gaze detection device, and an image display device for detecting information on a user's eyes, in which the wiring of the light source is simplified.

[0006] The detection device of the present disclosure detects information on a user's eyes. The detection device includes a frame attached to the user's face, a light source unit that irradiates infrared light, a light guide plate, and an imaging unit. The light guide plate is arranged in front of the user's eyes and has an emission layer that divides and replicates the infrared light incident from the light source unit and emits the replicated infrared light from a plurality of emission positions. The imaging unit images a plurality of infrared lights emitted from the plurality of emission positions and reflected by the user's eyes and the pupil of the user's eyes. The light source unit, the light guide plate, and the imaging unit are attached to the frame.

[0007] Further, the gaze detection device of the present disclosure includes the above-described detection device and an arithmetic unit that detects the gaze direction of the user's eyes based on the captured image by the imaging unit.

[0008] Further, the image display device of the present disclosure includes the above-described gaze detection device and a display arranged on the opposite side of the user's eyes with respect to the light guide plate.

[0009] According to the detection device, the gaze detection device, and the image display device of the present disclosure, the wiring of the light source can be simplified.

[0010] Schematic perspective view showing the overall configuration of Embodiment 1. Explanatory diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate in the view along the II-II arrow in Figure 1. Explanatory diagram showing an image of the user's eye captured by the imaging unit. Explanatory diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate in a modified example of Embodiment 1. Explanatory diagram illustrating the period of the diffraction structure of the emitter layer in Figure 4. Explanatory diagram illustrating the emitter layer arranged on the light guide plate of Embodiment 2. Explanatory diagram showing an image of the user's eye captured by the imaging unit. Explanatory diagram illustrating the emitter layer arranged on the light guide plate in a modified example of Embodiment 2. Explanatory diagram illustrating the direction of the inclination of the diffraction structure of the output layer in the first row of the emitter layer. Diagram illustrating the wave vector space of infrared light emitted from the output layer. Diagram illustrating the direction of the inclination of the diffraction structure of the output layer in the third column of the output layer. Diagram illustrating the wave vector space of infrared light emitted from the output layer in the third column of the output layer. Diagram illustrating an image of the user's eye captured by the imaging unit in a modified example of Embodiment 2. Schematic perspective view showing the overall configuration of Embodiment 3. Diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate in Embodiment 3. Diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate in a modified example of Embodiment 3. Schematic perspective view showing the overall configuration of Embodiment 4. Diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate in Embodiment 4.

[0011] (Embodiment 1) [1-1. Configuration] [1-1-1. Overall Configuration of Image Display Device and Eye-Tracking Device] A specific embodiment of the image display device 1 of the present disclosure will be described with reference to Figures 1 and 2. Figure 1 is a schematic perspective view showing the configuration of the image display device 1. Figure 2 is an explanatory diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate in the view along the line II-II in Figure 1, and shows infrared light irradiated to the user's right eye.

[0012] The image display device 1 is, for example, a glasses-type or goggle-type head-mounted display (hereinafter referred to as HMD). The image display device 1 comprises an eye-tracking device 2 and a display 3.

[0013] Display 3 displays images based on control from an external control unit. For example, Display 3 can be a backlit liquid crystal display, an organic light-emitting diode display, or a plasma display. Alternatively, Display 3 may use a screen that diffuses or reflects light, and generate images using a projector or scanning laser. Display 3 can display image content containing various types of information. The images displayed on Display 3 may be still images or moving images.

[0014] The gaze detection device 2 detects the direction of the user's gaze. The gaze detection device 2 comprises a detection device 5 that detects information about the user's eyes, and a calculation unit 7 that detects the gaze based on the detected information about the user's eyes.

[0015] The detection device 5 comprises a frame 11, a light source unit 13, a light guide plate 15, and an imaging unit 19. The detection device 5 irradiates the user's eye with infrared light using the light source unit 13 and the light guide plate 15, and the imaging unit 19 captures the infrared light irradiated onto the eye 103 along with the pupil, thereby detecting the positional relationship between the pupil and the irradiated infrared light.

[0016] The frame 11 is a support that fixes the detection device 5 to the user's face. In Embodiment 1, the frame 11 is of the eyeglass type, but it may also be of the goggle type. The frame 11 is attached to the user's face, for example, around the eyes or ears. The frame 11 may be made of, for example, resin, metal, or wood.

[0017] The light source unit 13 generates infrared light and irradiates it toward the light guide plate 15. The light source unit 13 is, for example, an infrared LED (Light Emitting Diode).

[0018] The light guide plate 15 is a so-called pupil-expanding type light guide that divides and duplicates the incident infrared light 23 and emits the duplicated infrared light 24 and 26 toward the user's eye 103 from different emission positions. In Embodiment 1, the infrared light 23 incident in the light guide plate 15 is divided into two infrared light beams 24 and 26 and emitted toward the user's eye 103.

[0019] The imaging unit 19 captures multiple infrared light beams 24, 26 emitted from multiple emission positions and reflected by the user's eye 103, as well as the pupil 104 of the user's eye 103. The imaging unit 19 is, for example, an infrared camera. The wavelength of light received by the imaging unit 19 is in the infrared region. The captured image is sent to the processing unit 7.

[0020] The arithmetic unit 7 detects the direction of the user's gaze from the eye 103 based on the image captured by the imaging unit 19. The arithmetic unit 7 can be implemented using, for example, semiconductor elements. The arithmetic unit 7 can be composed of, for example, a microcontroller, CPU, MPU, GPU, DSP, FPGA, or ASIC. The functions of the arithmetic unit 7 may be implemented using hardware alone, or by combining hardware and software. The arithmetic unit 7 has a storage unit such as an SSD or memory, and realizes predetermined functions by reading data and programs stored in the storage unit and performing various arithmetic processing. Instead of attaching the arithmetic unit 7 to the frame 11, the arithmetic unit 7 may be made wirelessly connectable to the imaging unit 19 and connected to an external computer.

[0021] Figure 3 is an explanatory diagram showing an image 29 of the user's eye captured by the imaging unit 19. Image 29 shows images (Purkinje images) 24a and 26a of two infrared light beams 24 and 26 reflected from the eye 103 along with the pupil 104, within the user's eye 103. Images 24a and 26a are corneal reflection images of the eye 103 due to the irradiated infrared light beams 24 and 26, respectively.

[0022] The calculation unit 7 uses a conventional gaze detection method, for example, employing the dark pupil method and the light pupil method according to the eye color, to detect the direction of the user's gaze through image processing based on the positional relationship between the center position of the pupil 104 in image 29 and the images 24a and 26a.

[0023] In image 29, having two images of reflected infrared light rather than one improves the accuracy of line-of-sight detection. Furthermore, a greater number of images of reflected infrared light improves the accuracy of line-of-sight detection.

[0024] [1-1-2. Configuration of the Light Guide Plate] Next, the light guide plate 15 will be described in detail. The light guide plate 15 includes a coupling portion 31 into which infrared light from the light source 13 is incident, and an emission layer 32 that divides and duplicates the incident infrared light 23. The light guide plate 15 is configured such that the incident infrared light undergoes total internal reflection. The coupling portion 31 changes the direction of propagation of the infrared light 23 incident from the light source 13. In Embodiment 1, the emission layer 32 expands the incident pupil in the left-right direction of the user's face. The divided and duplicated infrared light is emitted from the emission layer 32 toward the user's eye 103. The emission layer 32 has a first output layer 33 located at a first emission position and a second output layer 35 located at a second emission position. In Embodiment 1, the first output layer 33 and the second output layer 35 are separate, but they may be integrated.

[0025] The coupling portion 31 and the emission layer 32 each have diffraction power to diffract infrared light, and each has a diffractive optical element formed on it. The diffractive optical element is, for example, a holographic optical element or a diffractive structure element which is a periodic structure. The diffractive structure element is, for example, a diffraction grating or grating coupler, and the holographic optical element is, for example, a DOE (Diffractive Optical Element) or a volume hologram. By adjusting the diffraction angle of the infrared light at the emission layer 32 with respect to the diffraction angle of the infrared light at the coupling portion 31, the emission direction of the infrared light emitted from the emission layer can be adjusted. In the example shown in Figure 2, by making the diffraction angle at the coupling portion 31 and the diffraction angle at the emission layer 32 equal, the incident angle of infrared light at the coupling portion 31 and the emission angle of infrared light from the emission layer 32 can be made equal.

[0026] The grating coupler, which is a diffractive optical element positioned in the coupling portion 31, is, for example, a transmissive surface relief type diffraction grating. The coupling portion 31 couples infrared light to the light guide plate 15 by changing the propagation direction of infrared light incident from the outside toward the emission layer 32 due to diffraction power. In Embodiment 1, coupling means the state in which the light propagates within the light guide plate 15 under total internal reflection conditions.

[0027] The light guide plate 15 has a first main surface 16 and a second main surface 17 that face each other. In Embodiment 1, as shown in Figure 2, the coupling portion 31 and the emission layer 32 are arranged on the first main surface 16 that faces the user's eye 103. If the light source unit 13 is arranged on the side of the light guide plate 15 opposite to the user's eye 103, the coupling portion 31 may be arranged on the second main surface.

[0028] The infrared light coupled to the light guide plate 15 by the coupling portion 31 undergoes total internal reflection within the light guide plate 15 and propagates in the X-axis direction toward the center of the user's face, where it is divided and duplicated by the diffraction structure of the first output layer 33 located closer to the coupling portion 31. The first output layer 33 causes some of the infrared light 24 to be emitted from the light guide plate 15 toward the eye 103, and the remaining infrared light 25 is reflected back into the light guide plate 15. The remaining reflected infrared light 25 continues to propagate toward the center of the user's face while undergoing total internal reflection within the light guide plate 15, where the diffraction structure of the second output layer 35 located further away from the coupling portion 31 causes infrared light 26 to be emitted from the light guide plate 15 toward the eye 103.

[0029] The first output layer 33 and the second output layer 35 are, for example, transparent resin layers formed by nanoimprinting. In addition to nanoimprinting, the first output layer 33 and the second output layer 35 may also be formed by dry etching after laminating SiO2 on a glass substrate.

[0030] The infrared light 24 and 26 emitted toward the eye 103 are reflected by the cornea of ​​the eye 103 and incident on the imaging unit 19. As a result, the imaging unit 19 can acquire images 24a and 26a of the two infrared light beams 24 and 26 that irradiated onto the eye 103, along with the pupil 104 of the user's eye 103, as shown in Figure 3.

[0031] Next, a modified example of Embodiment 1 will be described with reference to Figure 4. In the modified example, the gaze detection device 2A has an emission layer 32 comprising a first output layer 33A, a second output layer 35A, and a third output layer 37 located at the third emission position. The infrared light 23 that propagates through total internal reflection within the light guide plate 15 is divided and duplicated by the diffraction structure of the first output layer 33A located closest to the coupling portion 31. The first output layer 33A emits some of the infrared light 24A from the light guide plate 15 toward the eye 103, and reflects the remaining infrared light 25A back into the light guide plate 15. The remaining reflected infrared light 25A propagates further toward the center of the user's face while undergoing total internal reflection within the light guide plate 15, and is then divided and duplicated by the diffraction structure of the second output layer 35A located on the next closest side. The second output layer 35A directs some of the infrared light 26A towards the eye 103 and emits it from the light guide plate 15, while reflecting the remaining infrared light 27 back into the light guide plate 15. The reflected remaining infrared light 27 propagates further towards the center of the user's face while undergoing total internal reflection within the light guide plate 15, and the diffraction structure of the third output layer 37, which is located on the side furthest from the coupling portion 31, causes infrared light 28 to be emitted from the light guide plate 15 towards the eye 103.

[0032] The diffraction structures of the output layers 33A, 35A, and 37 each have different periods. This allows the direction of the infrared light emitted from each emission position toward the eye 103 to be different for each emission position, enabling infrared light to be emitted toward the user's eye 103 without being constrained by the spatial limitations of each emission position.

[0033] Referring to Figure 5, the periods of the diffraction structures of the output layers 33A, 35A, and 37 will be explained. The periods of the diffraction structures 43, 45, and 47 of the output layers 33A, 35A, and 37, respectively, Pot1, Pot2, and Pot3, vary according to the distances L1, L2, and L3 from the coupling 31 to the output layers 33A, 35A, and 37, respectively, and decrease as the distance from the coupling 31 increases. In Figure 5, the distances L1, L2, and L3 from the coupling 31 to the output layers 33A, 35A, and 37, respectively, have the following relationship: L1 < L2 < L3 ... (1)

[0034] For example, consider a case where infrared light 23 is incident perpendicularly from the light source 13 to the coupling portion 31, and the light guide plate 15 and the eye 103 are facing each other. In this case, the output layer 33A is on the coupling portion 31 side with respect to the center of the pupil 104, and the output layers 35A and 37 are on the opposite side of the coupling portion 31 with respect to the center of the pupil 104. The period Pin of the diffraction structure 41 of the coupling portion 31, the period Put1 of the diffraction structure 43 of the output layer 33A, the period Put2 of the diffraction structure 45 of the output layer 35A, and the period Put3 of the diffraction structure 47 of the output layer 37 have the following relationship: Put3 < Put2 < Pin < Put1 ... (2)

[0035] The relative positions of Pin, Pout1, Pout2, and Pout3 change depending on the positional relationship between the center of the pupil 104 and the output layer, and the angle of incidence from the light source 13 to the coupling section 31, but the relationship in equation (3) below remains unchanged: Pout3 < Pout2 < Pout1 ... (Equation 3)

[0036] This allows for the concentration of multiple infrared beams directed towards the user's eye 103, thereby increasing the number of infrared beams that reach the eye 103.

[0037] [1-2. Effects, etc.] The detection device 5 of the present disclosure detects information of the user's eye 103. The detection device 5 comprises a frame 11 attached to the user's face, a light source unit 13 that emits infrared light 23, a light guide plate 15, and an imaging unit 19. The light guide plate 15 is positioned in front of the user's eye 103 and has an emission layer 32 that divides and duplicates the infrared light 23 incident from the light source unit 13 and emits the duplicated infrared light 24, 26 from multiple emission positions. The imaging unit 19 images the multiple infrared light 24, 26 emitted from the multiple emission positions and reflected by the user's eye 103, as well as the pupil 104 of the user's eye 103. The light source unit 13, the light guide plate 15, and the imaging unit 19 are attached to the frame 11.

[0038] By using a light guide plate 15 to divide the pupil of infrared light 23 from a single light source 13, multiple infrared beams 24 and 26 can be obtained to illuminate the user's eye 103, thus eliminating the need for the complex wiring that was previously required for multiple light sources.

[0039] (Embodiment 2) Next, the image display device, gaze detection device, and detection device of Embodiment 2 will be described with reference to Figures 6 and 7. Figure 6 is an explanatory diagram illustrating the emission layer 32B arranged on the light guide plate 15B of Embodiment 2. Figure 7 is an explanatory diagram showing the image of the user's eye captured by the imaging unit 19 in Embodiment 2.

[0040] In the modified example of Embodiment 1, the light guide plate 15A of the detection device 5A dilated the pupil in one dimension with respect to the incident infrared light 23, whereas in Embodiment 2, the light guide plate 15B of the detection device 5B dilates the pupil in two dimensions with respect to the incident infrared light 23. Except for this point and the points described below, the image display device, gaze detection device, and detection device 5B of Embodiment 2 are common to the image display device 1, gaze detection device 2A, and detection device 5A of Embodiment 1 and the modified example of Embodiment 1.

[0041] In Embodiment 2, the light guide plate 15B has an expansion portion 51 that expands the pupil in the X-axis direction for infrared light propagating from the coupling portion 31, and an emission layer 32B that expands the pupil in the Z-axis direction for infrared light propagating from the first expansion portion 51 and emits infrared light to the outside. The grooves of the diffraction structure element of the coupling portion 31 are formed parallel to the vertical direction.

[0042] The expansion unit 51, for example, has a transmissive relief-type diffraction grating, and duplicates the incident infrared light by splitting it into infrared light that travels in the direction of the center of the user's face (X-axis direction) and infrared light that travels in the vertical direction (Z-axis direction), i.e., toward the emission layer 32B, using diffraction power. The expansion unit 51 expands the infrared light in the horizontal direction and emits it toward the emission layer 32B located in the vertical direction (Z-axis direction). The expansion unit 51 functions as a propagation direction changing unit that changes the propagation direction of the infrared light toward the region from which the infrared light is extracted.

[0043] For example, in FIG. 6, in the expansion part 51, three diffraction gratings 52 arranged in the direction in which infrared light repeatedly undergoes total reflection are provided. The grooves of each diffraction grating 52 are formed to be inclined with respect to the vertical direction, for example, the inclination angle is 45 degrees. Each diffraction grating 52 divides the infrared light and makes the divided infrared light travel toward the emission layer 32B. The infrared light incident on the expansion part 51 is expanded by being replicated into three infrared lights in the X-axis direction. Thus, the infrared light propagated from the coupling part 31 is replicated by the diffraction grating 52 of the expansion part 51 arranged on the first main surface 16 while propagating in the X-axis direction while repeatedly undergoing total reflection at the first main surface 16 and the second main surface 17, and is emitted in the Z-axis direction.

[0044] The emission layer 32B replicates the incident infrared light by dividing it into infrared light that propagates in the Z-axis direction by diffraction power and infrared light that is emitted from the emission layer 32B to the outside. The emission layer 32B includes, for example, nine output layers 39A arranged in a matrix. The output layer 39A is, for example, a relief-type diffraction structure element. The grooves of the diffraction structure in the output layer 39A are formed, for example, parallel to the horizontal direction.

[0045] In FIG. 6, for example, in the emission layer 32B, the output layers 39A that divide and replicate the infrared light are arranged side by side in the vertical direction, three output layers 39A are arranged in each row in the light guide plate 15B, and a total of nine output layers 39A are arranged in three rows.

[0046] Each output layer 39A divides the infrared light and emits the divided infrared light to the outside. As a result, the incident infrared light is expanded by being replicated into three infrared lights in the vertical direction respectively. In this way, the light guide plate 15B can replicate nine infrared lights (pupils) from one incident infrared light, and can expand the irradiation area by replicating the light beam in the horizontal direction and the vertical direction respectively.

[0047] Therefore, from the user's perspective, the light guide plate 15B expands the infrared light that enters the coupling portion 31 and whose traveling direction is changed in the horizontal direction, and then further expands it in the vertical direction to emit the infrared light from the emission layer 32B. Here, the replication in the horizontal direction of the image includes not only replication in the complete horizontal direction but also replication in the substantially horizontal direction. Further, the replication in the vertical direction of the image includes not only replication in the complete vertical direction but also replication in the substantially vertical direction. Since nine infrared light beams are irradiated onto the user's eye 103, any of the infrared light beams will irradiate the eye even if the eye 103 moves slightly up, down, left, or right. Thereby, the allowable range of movement of the eye 103 can be increased.

[0048] In the emission layer 32B, each output layer 39A is arranged without changing the direction of the diffraction structure of each column. Thereby, an effect can be obtained in which the allowable range of the pupil position of the user's eye expands in a direction perpendicular to the column. Here, the column mentioned here is the propagation direction of the light in the light guide plate 15B that is branched by the expansion portion 51. The output layer 39A is described as being arranged in a columnar shape for easier understanding, but it does not necessarily have to be arranged in a grid pattern.

[0049] Also, the relationship between the period of the diffraction structure of each of the first output layer 33, the second output layer 35, and the third output layer 37 described in Embodiment 1 and the coupling portion 31 holds by replacing the coupling portion 31 with the diffraction grating 52 of the expansion portion 51 corresponding to each column. That is, by making the period of the diffraction structure of the output layer 39A closer to the diffraction grating 52 of the expansion portion 51 corresponding as a column larger than that of the output layer 39A on the farther side, more infrared light can be emitted to the eye.

[0050] The light guide plate 15B of the detection device in Embodiment 2 includes an extension portion 51 arranged along the direction of propagation of infrared light diffracted in the X-axis direction by the coupling portion 31, which serves as the light incident portion of the light guide plate 15B. The extension portion 51 has a plurality of diffraction gratings 52 arranged along the X-axis direction, and each diffraction grating 52 divides and duplicates infrared light propagating in the Z-axis direction intersecting the X-axis direction and infrared light propagating in the X-axis direction. The output layer 32B is arranged in the Z-axis direction from the extension portion 51 and has a plurality of diffraction gratings of output layers 39A arranged along the Z-axis direction. By using such a light guide plate 15B, the infrared light beam 53a can also be irradiated around the eye 103. In the captured image 29B shown in Figure 7, the infrared light beam irradiated onto the eye 103 is detected as an image 53, but the infrared light beam 53a irradiated around the eye is absorbed by the skin and is therefore not detected as an image. However, when the position of the eye 103 moves vertically, these infrared light beams 53a are reflected by the eye 103 and detected as an image. Therefore, multiple infrared light beams can be irradiated onto the user's eye 103 not only horizontally but also vertically, thereby increasing the detectable range of the eye 103.

[0051] Next, a modified example of Embodiment 2 will be described with reference to Figures 8A to 8E and Figure 9. Figure 8A is an explanatory diagram illustrating the emission layer 32C arranged on the light guide plate 15C in a modified example of Embodiment 2. Figure 8B is an explanatory diagram illustrating the direction of the inclination of the diffraction structure of the output layer 39B in the first row Cm1 of the emission layer 32C. Figure 8C is an explanatory diagram showing the wave vector k-space of the infrared light emitted from the output layer 39B in the first row Cm1 of the emission layer 32C. Figure 8D is an explanatory diagram illustrating the direction of the inclination of the diffraction structure of the output layer 39C in the third row Cm3 of the emission layer 32C. Figure 8E is an explanatory diagram showing the wave vector k-space of the infrared light emitted from the output layer 39C in the third row Cm3 of the emission layer 32C. Figure 9 is an explanatory diagram showing the image 29C of the user's eye captured by the imaging unit 19 in a modified example of Embodiment 2.

[0052] In the injection layer 32C, multiple output layers 39B, 39A, and 39C are arranged vertically in a first row Cm1, a second row Cm2, and a third row Cm3, respectively. The first row Cm1 is closest to the coupling portion 31 in the X-axis direction, and the second row Cm2 and the third row Cm3 are arranged in order away from the coupling portion 31 in the X-axis direction. The second row Cm2 is positioned to face the user's eye 103 directly.

[0053] By tilting the diffraction structures of the output layers 39B and 39C in the first row Cm1 and the second row Cm2 toward the user's eye 103, the infrared light emitted from each output layer 39B and 39C can be focused toward the user's eye 103.

[0054] As shown in Figure 8B, the tilt direction of the diffraction structure of the output layer 39B in the first row Cm1 is in the direction of the user's eye 103, that is, away from the coupling portion 31 in the X-axis direction. Regarding the wave vector space for infrared light emitted from the output layer 39B in the first row Cm1, when infrared light is incident perpendicularly on the coupling portion 31, the relationship between the wave vector k1 of the coupling portion 31, the wave vector k2 of the diffraction grating 52 of the extension portion 51, and the wave vector k3 of the output layer 39B is as shown in Figure 8C.

[0055] In contrast, the tilt direction of the diffraction structure of the output layer 39C in the third column Cm3 is, as shown in Figure 8D, the direction of the user's eye 103, that is, the direction approaching the coupling portion 31 in the X-axis direction. Regarding the wave vector space for infrared light emitted from the output layer 39C in the third column Cm3, when infrared light is incident perpendicularly on the coupling portion 31, the relationship between the wave vector k1 of the coupling portion 31, the wave vector k2 of the diffraction grating 52 of the expansion portion 51, and the wave vector k4 of the output layer 39C is as shown in Figure 8E.

[0056] In the modified detection device of Embodiment 2, the light guide plate 15C has a light guide plate in which the direction of the diffraction structure grooves of the respective output layers 39A, 39B, and 39C along the Z-axis direction in the output layer 32C is different from the direction of the diffraction structure grooves of the respective output layers 39A, 39B, and 39C along the Z-axis direction, which are spaced apart in the X-axis direction. More specifically, the direction of the diffraction structure grooves of the output layers 39A, 39B, and 39C in the output layer 32C is inclined toward the user's eye as it moves away from the user's eye in the X-axis direction. By using such a light guide plate 15C, as shown in Figure 9, multiple infrared lights can be irradiated closer to the user's eye 103 in the horizontal direction, and images 53 of each infrared light can be captured together with the pupil 104. As a result, the amount of infrared light hitting the eye in the horizontal direction increases, and the number of detectable images increases, thereby improving the measurement accuracy of gaze detection.

[0057] Furthermore, in the emission layer 32C, the period of the diffraction structure of each output layer 39A, 39B, and 39C along the Z-axis is greater on the side of the light guide plate 15C closer to the expansion portion 51 than on the side further from the expansion portion 51. In the case of this modified light guide plate 15C, as shown in Figure 9, by bringing the three vertical infrared rays closer together in the vertical direction, they can be brought closer to the pupil 104, thereby improving the accuracy of line-of-sight detection.

[0058] (Embodiment 3) Next, the image display device 1D, gaze detection device 2D, and detection device 5D of Embodiment 3 will be described with reference to Figures 10 and 11. Figure 10 is a schematic perspective view showing the overall configuration of the image display device 1D of Embodiment 3. Figure 11 is an explanatory diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate 15D in Embodiment 3.

[0059] The detection device 5 of Embodiment 1 utilized infrared light from a light source unit 13 positioned on the user's eye 103 side relative to the light guide plate 15, with its direction of travel changed at the coupling unit 31, and the resulting infrared light was totally reflected within the light guide plate 15. In the detection device 5D of Embodiment 3, the light source unit 13 is positioned on the opposite side of the user's eye 103 relative to the light guide plate 15D, and the transmitted light from the infrared light source unit 13 that passes through the light guide plate 15D is also utilized. Except for this point and the points described below, the image display device 1D, gaze detection device 2D, and detection device 5D of Embodiment 3 are common to the image display device 1, gaze detection device 2, and detection device 5 of Embodiment 1.

[0060] The light source unit 13, positioned on the opposite side of the light guide plate 15D from the user's eye 103, irradiates infrared light 23 toward the light guide plate 15D and the user's eye 103. A separation layer 61 is positioned at the incident position of the infrared light 23 on the light guide plate 15D. The separation layer 61 is, for example, a diffractive optical element.

[0061] The separation layer 61 separates the infrared light by allowing a portion of the incident infrared light 23 to travel in a straight line and diffracting the remainder in both directions along the X axis. The diffracted infrared light 64 and 65 propagate through the light guide plate 15D by total internal reflection. The infrared light 63 that travels in a straight line through the separation layer 61 passes through the light guide plate 15D and enters the user's eye 103. The incident infrared light 63 is reflected by the cornea of ​​the user's eye 103 and enters the imaging unit 19.

[0062] The infrared light 64 diffracted by the separation layer 61 is partially emitted from the first output layer 33D to become infrared light 24D, which enters the user's eye 103. The infrared light 24D is reflected by the cornea of ​​the user's eye 103 and enters the imaging unit 19. Similarly, the infrared light 65 diffracted by the separation layer 61 is partially emitted from the second output layer 35D to become infrared light 26D, which enters the user's eye 103. The infrared light 26D is reflected by the cornea of ​​the user's eye 103 and enters the imaging unit 19.

[0063] Therefore, since the image captured by the imaging unit 19 contains the pupil 104 of the user's eye 103 and images of multiple infrared lights, the image display device 1D, gaze detection device 2D, and detection device 5D in Embodiment 3 can obtain the same effects as in Embodiment 1.

[0064] Next, a modified example of Embodiment 3 will be described with reference to Figure 12. Figure 12 is an explanatory diagram illustrating the optical path of infrared light, including a cross-section of the light guide plate 15E in a modified example of Embodiment 3.

[0065] In the modified embodiment of Embodiment 3, the light guide plate 15E has a configuration in which the first output layer 33D and the second output layer 35D are omitted from the light guide plate 15D of Embodiment 3.

[0066] In a modified example of Embodiment 3, the infrared light 64 diffracted by the separation layer 61 passes through the light guide plate 15E and exits the light guide plate 15E, entering the user's eye 103. The infrared light 64 is reflected by the cornea of ​​the user's eye 103 and enters the imaging unit 19. Similarly, the infrared light 65 diffracted by the separation layer 61 passes through the light guide plate 15E and exits the light guide plate 15E, entering the user's eye 103. The infrared light 65 is reflected by the cornea of ​​the user's eye 103 and enters the imaging unit 19. Therefore, the image captured by the imaging unit 19 contains images of the pupil 104 of the user's eye 103 and images of the multiple infrared light beams 63, 64, and 65.

[0067] The detection device 5E in a modified embodiment of Embodiment 3 comprises a frame 11 attached to the user's face, a light source unit 13 that emits infrared light, a light guide plate 15E positioned in front of the user's eye 103 that emits infrared light 23 incident from the light source unit 13 from multiple emission positions, and an imaging unit 19 that images multiple infrared light beams 63, 64, 65 emitted from the multiple emission positions and reflected by the user's eye 103, as well as the pupil 104 of the user's eye 103. The light source unit 13, the light guide plate 15E, and the imaging unit 19 are attached to the frame 11. The light guide plate 15E has a separation layer 61 that separates the infrared light 23 incident from the light source unit 13 into multiple infrared light beams 63, 64, 65, and transmits the separated multiple infrared light beams 63, 64, 65 to emit from multiple emission positions.

[0068] Therefore, by using the light guide plate 15E of the modified embodiment 3, multiple infrared lights can be irradiated onto the user's eye 103, and images of each infrared light 63, 64, and 65 can be captured together with the pupil 104. Thus, the detection device 5E in the modified embodiment 3 can omit complex wiring, similar to the detection device 5 in embodiment 1.

[0069] (Embodiment 4) Next, the image display device 1F, gaze detection device 2F, and detection device 5F of Embodiment 4 will be described with reference to Figures 13 and 14. In Embodiment 1, the imaging unit 19 directly captured infrared light reflected by the eye 103, but in Embodiment 4, the imaging unit 19 of the detection device 5F captures the infrared light reflected by the eye 103 by further reflecting it with the reflective layer 9. Except for this point and the points described below, the image display device 1F, gaze detection device 2F, and detection device 5F of Embodiment 4 are common to the image display device 1, gaze detection device 2, and detection device 5 of Embodiment 1.

[0070] In the image display device 1B of Embodiment 4, a reflective layer 9 is placed between the light guide plate 15F and the display 3. The reflective layer 9 is positioned on the second main surface 17 side of the light guide plate 15F, opposite to the user's eye 103.

[0071] The reflective layer 9 is, for example, a volume hologram, a diffraction grating, or a polarization-selective hologram. Instead of directly detecting the infrared light 24A and 26A reflected from the eye 103 in the imaging unit 19, it is detected via the reflective layer 9 in the imaging unit 19. This makes it possible to detect reflected light with a small reflection angle from the eye 103, allowing observation of the eye 103 from a direction closer to the front, rather than from an oblique angle with a large angle. The images of the infrared light 24A and 26A reflected from the eye 103 become clearer in the captured image, making it easier for the processing unit 7 to detect the infrared light image.

[0072] (Other Embodiments) As described above, the above embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Therefore, other embodiments are described below as examples.

[0073] In the above embodiment, the exit layers 32, 32B, and 32C are each composed of multiple diffraction structure elements, but are not limited to this. In the exit layers 32, 32B, and 32C, multiple diffraction structure elements divided into regions may be integrated to form a single exit layer 32, 32B, or 32C. The same applies to the extended portion 51.

[0074] (Outline of Embodiments) (1) The detection device of the present disclosure detects information of the user's eyes. The detection device comprises a frame attached to the user's face, a light source unit that emits infrared light, a light guide plate positioned in front of the user's eyes and having an emission layer that divides and duplicates the infrared light incident from the light source unit and emits the duplicated infrared light from a plurality of emission positions, and an imaging unit that images a plurality of infrared lights emitted from the plurality of emission positions and reflected by the user's eyes, as well as the pupil of the user's eyes. The light source unit, the light guide plate, and the imaging unit are attached to the frame.

[0075] By using a light guide plate to split infrared light from a single light source into pupil-splitting beams, multiple infrared beams can be directed towards the user's eye, thus eliminating the need for the complex wiring previously required for multiple light sources.

[0076] (2) In the detection device of (1), the emission layer is arranged at multiple emission positions and includes a diffraction grating that emits a portion of the infrared light incident from the light source through the light guide plate and reflects the remaining infrared light into the light guide plate.

[0077] (3) In the detection device of (2), the periodic structure of the diffraction grating differs depending on the emission position.

[0078] (4) In the detection device of (2) or (3), the period of the diffraction grating is greater on the side closer to the light incident part than on the side further from the light incident part. This makes it possible to focus multiple infrared light beams directed towards the user's eye, thereby increasing the number of infrared light beams that reach the eye.

[0079] (5) In any one of the detection devices described in (1) to (4), the emission layer focuses multiple infrared beams of light two-dimensionally onto the user's eye. This increases the irradiation area of ​​the infrared beam.

[0080] (6) The detection device of (5) includes an expansion section arranged along the direction of propagation of infrared light diffracted in a first direction by the light incident section of the light guide plate. The expansion section has a plurality of diffraction gratings arranged along the first direction, and each diffraction grating divides and duplicates infrared light traveling in a second direction intersecting the first direction and infrared light traveling in the first direction. The output layer is arranged in a second direction from the expansion section and has a plurality of diffraction gratings arranged along the second direction.

[0081] (7) In the detection device of (6), the direction of the grooves of each diffraction grating in the emission layer along the second direction is different from the direction of the grooves of each diffraction grating in the second direction which are spaced apart in the first direction.

[0082] (8) In the detection device of (7), the direction of the grooves of the diffraction grating of the emission layer is inclined toward the user's eye as it moves away from the user's eye in the first direction.

[0083] (9) In the detection device of (6), the period of each diffraction grating in the emission layer along the second direction is greater on the side closer to the expansion portion of the light guide plate than on the side further from the expansion portion.

[0084] (10) In any one of the detection devices from (1) to (9), each injection layer is discontinuously and individually separated. This simplifies the process of manufacturing the injection layers.

[0085] In the detection device of (11)(2), the light guide plate has a separation layer that separates the infrared light incident from the light source into multiple infrared light beams, and the infrared light separated by the separation layer propagates and is emitted from the diffraction gratings of the multiple emission layers.

[0086] (12) In any one of the detection devices described in (1) to (11), the light guide plate has a reflective layer that reflects multiple infrared light reflected by the user's eye to the light receiving unit. This allows the user's eye to be observed from the front rather than from an oblique angle, and the image of the infrared light reflected by the eye becomes clearer in the captured image.

[0087] (13) The detection device of the present disclosure detects information of the user's eyes. The detection device comprises a frame attached to the user's face, a light source unit that emits infrared light, a light guide plate positioned in front of the user's eyes and emitting infrared light incident from the light source unit from multiple emission positions, and an imaging unit that images the multiple infrared lights emitted from the multiple emission positions and reflected by the user's eyes, as well as the pupil of the user's eye. The light source unit, the light guide plate, and the imaging unit are attached to the frame. The light guide plate has a separation layer that separates the infrared light incident from the light source unit into multiple infrared lights, and transmits the separated multiple infrared lights and emits them from multiple emission positions.

[0088] (14) The gaze detection device of the present disclosure comprises one of the detection devices (1) to (13) and a calculation unit that detects the direction of the user's gaze based on an image captured by an imaging unit.

[0089] (15) The image display device of the present disclosure comprises the gaze detection device of (14) and a display positioned on the opposite side of the user's eyes from the light guide plate.

[0090] This disclosure is applicable to detection devices, gaze detection devices, and image display devices that detect information about a user's eyes.

[0091] 1 Image display device 2 Eye-line detection device 3 Display 5 Detection device 7 Processing unit 9 Reflection layer 11 Frame 13 Light source unit 15, 15B, 15C, 15D, 15E, 15F Light guide plate 16 First main surface 17 Second main surface 19 Imaging unit 23, 24, 25, 26, 27, 28 Infrared light 24a, 26a Image 29 Image 31 Coupling unit 32, 32B, 32C Emission layer 33, 33A, 33D First output layer 35, 35A, 35D Second output layer 37 Third output layer 39A, 39B, 39C Output layer 41, 43, 45, 47 Diffraction structure 51 Expansion unit 52 Diffraction grating 53 Image 53a Light beam 61 Separation layer 63, 64, 65 Infrared light 103 Eye 104 Pupil

Claims

1. A detection device for detecting information of a user's eyes, comprising: a frame attached to the user's face; a light source unit that emits infrared light; a light guide plate positioned in front of the user's eyes and having an emission layer that divides and duplicates the infrared light incident from the light source unit and emits the duplicated infrared light from a plurality of emission positions; and an imaging unit that images a plurality of infrared lights emitted from the plurality of emission positions and reflected by the user's eyes, as well as the pupil of the user's eye, wherein the light source unit, the light guide plate, and the imaging unit are attached to the frame.

2. The detection device according to claim 1, wherein the emission layer includes a diffraction grating, each of which is arranged at the plurality of emission positions, and emits a portion of the infrared light incident from the light source from the light guide plate and reflects the remaining infrared light into the light guide plate.

3. The detection device according to claim 2, wherein the periodic structure of the diffraction grating differs depending on the emission position.

4. The detection device according to claim 3, wherein the period of the diffraction grating is greater on the side of the light guide plate closer to the light incident part than on the side further from the light incident part.

5. The detection device according to claim 3, wherein the light guide plate focuses a plurality of infrared lights emitted from the emission layer in a two-dimensional manner onto the user's eye.

6. The detection device according to claim 5, comprising an extension portion arranged along the direction of propagation of infrared light diffracted in a first direction by the light incident portion of the light guide plate, wherein the extension portion has a plurality of diffraction gratings arranged along the first direction, and each diffraction grating divides and duplicates infrared light propagating in a second direction intersecting the first direction and infrared light propagating in the first direction, and the emission layer is arranged in the second direction from the extension portion and has a plurality of diffraction gratings arranged along the second direction.

7. The detection device according to claim 6, wherein the direction of the grooves of each diffraction grating in the emission layer along the second direction is different from the direction of the grooves of each diffraction grating in the second direction which are spaced apart in the first direction.

8. The detection device according to claim 7, wherein the direction of the grooves of the diffraction grating of the emission layer is inclined toward the user's eye as it moves away from the user's eye in the first direction.

9. The detection device according to claim 6, wherein the period of each diffraction grating in the emission layer along the second direction is greater on the side of the light guide plate closer to the expansion portion than on the side further from the expansion portion.

10. The detection device according to claim 5, wherein each of the aforementioned injection layers is discontinuous and individually separated.

11. The detection device according to claim 2, wherein the light guide plate has a separation layer that separates infrared light incident from the light source into a plurality of infrared beams, and the infrared light separated by the separation layer is propagated and emitted from the diffraction gratings of the plurality of emission layers.

12. The detection device according to claim 1, wherein the light guide plate has a reflective layer that reflects a plurality of infrared lights reflected by the user's eye to the light receiving unit.

13. A detection device for detecting information of a user's eyes, comprising: a frame attached to the user's face; a light source unit that emits infrared light; a light guide plate positioned in front of the user's eyes and emitting infrared light incident from the light source unit from a plurality of emission positions; and an imaging unit that images a plurality of infrared lights emitted from the plurality of emission positions and reflected by the user's eyes, and the pupil of the user's eyes, wherein the light source unit, the light guide plate, and the imaging unit are attached to the frame, and the light guide plate has a separation layer that separates infrared light incident from the light source unit into a plurality of infrared lights, and transmits the separated plurality of infrared lights and emits them from a plurality of emission positions.

14. A gaze detection device comprising: a detection device according to any one of claims 1 to 13; and a calculation unit that detects the direction of the user's gaze based on an image captured by the imaging unit.

15. An image display device comprising the gaze detection device according to claim 14 and a display positioned opposite the user's eye to the light guide plate.

Images