Head-mounted displays

Abstract

A head-mounted display that displays an image within a user's field of vision, the head-mounted display comprising: an image display unit that generates an image to be displayed; and a first light guide plate and a second light guide plate that replicate image light from the image display unit, the first light guide plate and the second light guide plate each having a set of parallel main surfaces that enclose the image light through internal reflection, the first light guide plate having an incident surface that reflects the image light inward and two or more exiting reflective surfaces that emit image light to the second light guide plate, the second light guide plate having an input section that couples the image light from the first light guide plate into the interior and an output section that emits image light to the user's pupil, the angle between the replication direction of the image light from the first light guide plate and the replication direction of the image light from the second light guide plate being less than 90°.

Description

Technical Field

[0001] This invention relates to a head-mounted display that is worn on a user's head and displays images within their field of vision. Background Technology

[0002] Wearable devices such as head-mounted displays (HMDs) not only require display performance such as good field of view and image visibility, but also require a small and comfortable construction.

[0003] As prior art in this technical field, there is Patent Document 1. Patent Document 1 discloses an optical device with the following structure: a substrate that transmits light through a flat surface, an optical unit for connecting light into the substrate through internal reflection, and a plurality of partially reflective surfaces of the substrate, the partially reflective surfaces being parallel to each other and not parallel with respect to any edge of the substrate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2003-536102 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The optical system of an HMD includes: an image display unit having an illumination unit that transmits light emitted from a light source unit to a small display unit; and a projection unit that projects image light (virtual image) generated by the image display unit. If the HMD shifts position relative to the user's pupil, the image will be cropped. Therefore, for example, the eyeglass frame can be enlarged by using a light guide plate constituting the reproduction unit, but this enlargement results in a larger optical system size and reduced optical efficiency.

[0009] In the aforementioned patent document 1, no consideration was given to these issues in achieving both the enlargement of the eyeglass frame and the miniaturization of the HMD optical system.

[0010] The purpose of this invention is to provide an HMD that balances miniaturization of the optical system with enlargement of the eyeglass frame.

[0011] Methods for solving problems

[0012] As an example, the present invention provides a head-mounted display that displays images within a user's field of vision. The head-mounted display includes: an image display unit that generates an image to be displayed; and a first light guide plate and a second light guide plate that replicate image light from the image display unit. The first light guide plate and the second light guide plate each have a set of parallel main surfaces that enclose the image light through internal reflection. The first light guide plate has an incident surface that reflects the image light inward and two or more exiting reflective surfaces that emit image light to the second light guide plate. The second light guide plate has an input section that couples the image light from the first light guide plate into the interior and an output section that emits image light to the user's pupil. The angle between the replication direction of the image light from the first light guide plate and the replication direction of the image light from the second light guide plate is less than 90°.

[0013] Invention Effects

[0014] According to the present invention, an HMD that balances miniaturization of the optical system and enlargement of the eyeglass frame can be provided. Attached Figure Description

[0015] Figure 1A This is a structural block diagram of the HMD in Example 1.

[0016] Figure 1B It means Figure 1A The diagram shows an example of the hardware structure of an HMD.

[0017] Figure 2 This is a structural block diagram of the virtual image generation unit in Embodiment 1.

[0018] Figure 3 This is a diagram illustrating how the HMD is used in Example 1.

[0019] Figure 4A This is a structural diagram of the previous virtual image generation unit.

[0020] Figure 4B This is a structural diagram of the previous virtual image generation unit.

[0021] Figure 5A This is a structural diagram of the first light guide plate and the second light guide plate in Example 1.

[0022] Figure 5B This is a structural diagram of the first light guide plate and the second light guide plate in Example 1.

[0023] Figure 6 This is a comparative structural diagram of the image light copying unit without light enclosure and the first light guide plate in Embodiment 1.

[0024] Figure 7 This is a schematic diagram illustrating the propagation of light within the first light guide plate in Embodiment 1.

[0025] Figure 8A This is a variation of the first and second light guide plates in Example 1.

[0026] Figure 8B This is a variation of the first and second light guide plates in Example 1.

[0027] Figure 9 This is a schematic diagram of the technical problem of the first light guide plate in Embodiment 1.

[0028] Figure 10A This is a structural diagram of the first light guide plate and the second light guide plate in Example 2.

[0029] Figure 10B This is a structural diagram of the first light guide plate and the second light guide plate in Example 2.

[0030] Figure 11A This is a structural diagram of a modified example of the first light guide plate and the second light guide plate in Embodiment 2.

[0031] Figure 11B This is a structural diagram of a modified example of the first light guide plate and the second light guide plate in Embodiment 2.

[0032] Figure 12 This is a schematic diagram showing the light path reflected from the back.

[0033] Figure 13 This is an example of the structural diagram of the first light guide plate and the second light guide plate.

[0034] Figure 14 This is a diagram illustrating an example of HMD usage in Example 3.

[0035] Figure 15 This is a structural block diagram of the HMD in Example 3. Detailed Implementation

[0036] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are illustrative of the invention, and appropriate omissions and simplifications have been made for clarity. The present invention can also be implemented in various other ways. Unless otherwise specified, each constituent element may be a single element or a plurality of elements.

[0037] To facilitate understanding of the invention, the positions, sizes, shapes, and extents of the constituent elements shown in the accompanying drawings may not represent their actual positions, sizes, shapes, or extents. Therefore, the invention is not necessarily limited to the positions, sizes, shapes, and extents disclosed in the accompanying drawings.

[0038] In the following descriptions, various information is sometimes represented by terms such as "table" or "list," but information can also be represented using other data structures. To indicate independence from data structures, "XX table," "XX list," etc., are sometimes referred to as "XX information." When describing identification information, terms such as "identification information," "identifier," "name," "ID," and "number" can be interchanged.

[0039] When multiple constituent elements have the same or identical functions, different subscripts are sometimes used to describe the same symbol. However, when it is not necessary to distinguish these multiple constituent elements, the subscripts are sometimes omitted for description.

[0040] Furthermore, in the following description, the processing performed by executing a program is sometimes described, but the program is executed by a processor (e.g., CPU (Central Processing Unit), GPU (Graphics Processing Unit)), which appropriately uses storage resources (e.g., memory) and / or interface devices (e.g., communication ports) to perform the determined processing; therefore, the main body of the processing can also be the processor. Similarly, the main body of the processing performed by executing a program can also be a controller, device, system, computer, or node having a processor. The main body of the processing performed by executing a program can be any arithmetic unit, or it can be a dedicated circuit that performs specific processing (e.g., FPGA (Field-Programmable Gate Array), ASIC (Application Specific Integrated Circuit)).

[0041] The program can also be installed from a program source onto a device such as a computer. The program source can be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server can also include a processor and storage resources for storing the programs to be distributed. The processor of the program distribution server distributes the programs to other computers. Furthermore, in the following description, two or more programs can be implemented as one program, or one program can be implemented as two or more programs.

[0042] Example 1

[0043] Figure 1A This is a structural block diagram of the HMD in this embodiment. Figure 1AThe HMD1 includes a virtual image generation unit 101, a control unit 102, an image signal processing unit 103, a power supply unit 104, a storage unit 105, a sensing unit 106, a communication unit 107, a sound processing unit 108, a shooting unit 109, and input / output units 91 to 93.

[0044] The virtual image generation unit 101 magnifies and projects the image generated by the miniature display unit as a virtual image, displaying augmented reality (AR) and mixed reality (MR) images in the wearer's (user's) field of vision.

[0045] The control unit 102 provides overall control of the HMD1. The control unit 102 implements its functions through a computing device such as a CPU. The image signal processing unit 103 supplies image signals for display to the display unit within the virtual image generation unit 101. The power supply unit 104 supplies power to all parts of the HMD1.

[0046] The storage unit 105 stores information required for processing by each part of the HMD1, as well as information generated by each part of the HMD1. Additionally, when the control unit 102 functions via the CPU, it stores programs and data executed by the CPU. The storage unit 105 may be composed of storage devices such as RAM (Random Access Memory), flash memory, HDD (Hard Disk Drive), or SSD (Solid State Drive).

[0047] The sensing unit 106 is connected to various sensors via the input / output unit 91, which acts as a connector. Based on the signals detected by these sensors, it detects the HMD1's posture (i.e., the user's posture, the direction of the user's head), movement, ambient temperature, and other parameters. These various sensors include, for example, tilt sensors, accelerometers, temperature sensors, and GPS (Global Positioning System) sensors that detect the user's location information.

[0048] The communication unit 107 communicates with external information processing devices via the input / output unit 92, which acts as a connector, through short-range wireless communication, long-range wireless communication, or wired communication. Specifically, communication is conducted via Bluetooth, Wi-Fi, mobile communication networks, Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), etc.

[0049] The sound processing unit 108 is connected to sound input / output devices such as microphones, headphones, and speakers via the input / output unit 93, which serves as a connector, to input or output sound signals. The imaging unit 109 is, for example, a small camera or a small time-of-flight (TOF) sensor, to capture images in the user's field of vision direction of the HMD1.

[0050] Figure 1B This is a diagram illustrating an example of the hardware structure of HMD1. For example... Figure 1B As shown, HMD1 includes CPU 201, system bus 202, ROM (Read Only Memory) 203, RAM 204, storage device 210, communication processor 220, power supply 230, video processor 240, audio processor 250, and sensor 260.

[0051] CPU 201 is a microprocessor unit that controls the HMD1 as a whole. CPU 201 corresponds to control unit 102. System bus 202 is a data communication path used for sending and receiving data between CPU 201 and various operating modules in HMD1.

[0052] ROM203 is a memory that stores basic operating programs and other operating programs. For example, it can use rewritable ROMs such as EEPROM (Electrically Erasable Programmable Read-Only Memory) or flash ROM.

[0053] RAM204 is the working area for executing basic or other programs. ROM203 and RAM204 can be integrated with CPU201. Alternatively, ROM203 may not be... Figure 1B Instead of a separate structure as shown, it uses a portion of the storage area within storage device 210.

[0054] Storage device 210 stores the operating program, operating settings, and personal information 210a of the user using HMD1, etc., of the information processing device 100. While not specifically illustrated below, it can also store operating programs downloaded from the network and various data generated by those operating programs. Furthermore, some storage areas of storage device 210 can be replaced by part or all of the functionality of ROM 203. Storage device 210 can be, for example, a flash memory ROM, SSD, HDD, or similar device. ROM 203, RAM 204, storage device 210, and storage unit 105 correspond to each other. Additionally, the operating programs stored in ROM 203 or storage device 210 can be updated and have their functionality expanded by performing download processing from various devices on the network.

[0055] The communication processor 220 is configured to include a LAN (Local Area Network) communicator 221, a telephone network communicator 222, an NFC (Near Field Communication) communicator 223, and a Bluetooth communicator 224. The communication processor 220 corresponds to the communication unit 107. Figure 1B The example shown illustrates a scenario where the communication processor 220 includes a LAN communicator 221, an NFC communicator 223, and a Bluetooth communicator 224, but it can also be implemented as follows: Figure 1A As described, these devices are connected external to the HMD1 via the input / output unit 92. The LAN communicator 221 connects to the network via an access point and transmits and receives data with devices on the network. The NFC communicator 223 transmits and receives data wirelessly when a corresponding reader / writer is nearby. The Bluetooth communicator 224 transmits and receives data wirelessly with a nearby information processing device. Furthermore, the HMD1 may also include a telephone network communicator 222 for transmitting and receiving calls and data with the base station 105 of the mobile phone communication network.

[0056] The virtual image generation mechanism 225 includes an image display unit 120, a projection unit 121, a first light guide plate 122, and a second light guide plate 123. The virtual image generation mechanism 225 corresponds to the virtual image generation unit 101. Regarding the specific structure of the virtual image generation mechanism 225, [further details are needed]. Figure 2 To be described later.

[0057] Power supply unit 230 is a power supply device that supplies power to HMD1 according to specified standards. Power supply unit 230 corresponds to power supply section 104. Figure 1B The example shown is that the HMD1 includes a power supply 230, but it can also be connected as an external device to the HMD1 via any of the input / output sections 91 to 93, from which the HMD1 receives power.

[0058] The video processor 240 is configured to include a display 241, an image signal processor 242, and a camera 243. The video processor 240 corresponds to the image signal processing unit 103 and the virtual image generation unit 101. Furthermore, the camera 243 corresponds to the capturing unit 109, and the display 241 corresponds to the aforementioned miniature display unit. Figure 1B The example shown illustrates a scenario where the video processor 240 includes a display 241 and a camera 243, but as in... Figure 1A As explained, they can also be connected as external devices to HMD1 via input / output units (e.g., input / output unit 93).

[0059] Display 241 is, for example, a liquid crystal display, a digital micromirror device, an organic EL display, a miniature LED display, a MEMS (Micro Electro Mechanical Systems), a fiber optic scanning device, or other display devices, which displays image data processed by image signal processor 242. Image signal processor 242 causes display 241 to display the input image data. Camera 243 is a camera unit that functions as an imaging device. This imaging device uses electronic devices such as CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) sensors to convert light input from the lens into electrical signals to input image data of the surroundings and objects.

[0060] The audio processor 250 includes a speaker 251, a sound signal processor 252, and a microphone 253. The audio processor 250 corresponds to the sound processing unit 108. Figure 1B The example shown illustrates a case where the audio processor 250 includes a speaker 251 and a microphone 253, but as in... Figure 1A As explained, they can also be connected as external devices to the HMD1 via the input / output unit 93.

[0061] Speaker 251 outputs sound signals processed by sound signal processor 252. Sound signal processor 252 outputs input sound data to speaker 251. Microphone 253 converts sound into sound data and outputs it to sound signal processor 252.

[0062] Sensor 260 is a sensor group used to detect the state of information processing device 100, and includes a GPS receiver 261, a gyroscope sensor 262, a geomagnetic sensor 263, an accelerometer sensor 264, an illuminance sensor 265, and a proximity sensor 266. Sensor 260 corresponds to sensing unit 106. Figure 1B The example shown illustrates a sensor 260 that includes a GPS receiver 261, a gyroscope sensor 262, a geomagnetic sensor 263, an accelerometer 264, an illuminance sensor 265, and a proximity sensor 266. However, it can also be implemented as shown in the example. Figure 1A As explained, they are connected as external devices to the HMD1 via the input / output unit 91. These sensors are conventionally known sensor groups, so their description is omitted here. Figure 1B The structure of the HMD1 shown is just one example and does not necessarily include all of these components.

[0063] Figure 2This is a structural block diagram of the virtual image generation unit 101 in this embodiment. The virtual image generation unit 101 consists of an image display unit 120, a projection unit 121, a first light guide plate 122, and a second light guide plate 123. The image display unit 120 is a device for generating the image to be displayed, which illuminates light from a light source such as an LED or laser onto a built-in miniature display unit (not shown). The miniature display unit is a component for displaying images, and may use a liquid crystal display, a digital micromirror device, an organic EL display, a miniature LED display, a MEMS (Micro Electro Mechanical Systems), a fiber optic scanning device, etc. The projection unit 121 is a device for magnifying the image light from the image display unit 120 and projecting it as a virtual image. The first light guide plate 122 replicates the image light to enlarge the eyeglass frame. The second light guide plate 123 replicates the image light for enlarging the eyeglass frame in a different direction than the first light guide plate 122, and transmits the image light from the projection unit 121 and the first light guide plate 122 to the user's pupil 20. Users can visually confirm images by focusing the image light onto the retina within the pupil 20.

[0064] Figure 3 This is a diagram illustrating how HMD1 is used in this embodiment. Figure 3 This represents a top-down view from above user 2's head. The X-axis is horizontal, the Y-axis is vertical, and the Z-axis is the visual axis, which serves as the direction of user 2's gaze. The directions of the X, Y, and Z axes will be defined similarly in subsequent figures.

[0065] The HMD1 is worn on the head of user 2, allowing the image generated by the virtual image generation unit 101 to be transmitted to the user's pupil 20 via the second light guide plate 123. At this time, user 2 can visually confirm the image (virtual image) within a portion of the image display area 111 within their field of vision, enabling them to visually confirm the external environment (perspective type). Figure 3 The diagram shows the structure for displaying an image in a single eye, but it could also be a dual-eye structure. Furthermore, the HMD1 can capture the user 2's field of vision within the imaging unit 109 of Figure 1.

[0066] Next, Figure 4 shows a conventional structural diagram of the virtual image generation unit 101 using a mirror array type light guide plate 123. In Figure 4, (a)( Figure 4A (b) indicates the virtual image generation unit 101 as observed from the Z-axis direction, which is the viewing axis direction. Figure 4BThe symbol 101 represents the virtual image generation unit as viewed from the Y-axis direction, which is vertical. The light guide plate 123 is a flat plate with two main parallel planes (171, 172), and has at least two or more exit reflective surfaces 173 inside as partial reflective surfaces in order to enlarge the eyeglass frame. The exit reflective surfaces 173, which have reflective films that reflect a portion of the image light, have the function of replicating the image light of the projection unit 121 in the X-axis direction. In addition, in order to prevent the reflected image light from angularly shifting, it is preferable that the exit reflective surfaces 173 are approximately parallel to each other.

[0067] From a practical point of view, it is preferable that the eyeglass frame formed by the virtual image generation unit 101 is enlarged in the two-dimensional direction. Since the light guide plate 123 is enlarged only in the horizontal direction, the optical engine needs to input image light with a larger beam diameter in the vertical direction. Therefore, it is necessary to reduce the F-value of the optical system of the image display unit 120 in this direction, thereby increasing the size of portion A of the image display unit 120 and the projection unit 121 in FIG. 4(a), and making the virtual image generation unit 101 larger. Considering the characteristics of an HMD as a device worn on the body, weight and design aesthetics are also important factors, and these factors are key to increasing the product's value.

[0068] Thus, in HMD (Hardware Modulation), there is a challenge in balancing the enlargement and miniaturization of the eyeglass frame in two dimensions. The solutions to these problems will be explained below.

[0069] Figure 5A , 5B This is a structural diagram of the virtual image generation unit 101 in this embodiment. Figure 5A , 5B In the figure, the same symbols are used to mark the same structures as those in Figure 4, and their descriptions are omitted. Figure 5A , 5B The examples illustrate the cases where the virtual image generation unit 101 is positioned on the side of the head and the case where it is positioned on the top of the head. In this embodiment, the aforementioned problem is solved by the first light guide plate 122 and the second light guide plate 123. As described above, from the viewpoint of visual recognizability of the image, it is preferable that the eyeglass frame formed by the virtual image generation unit 101 is enlarged in the two-dimensional direction. To enlarge the eyeglass frame in two dimensions, the first light guide plate 122... Figure 5A The vertical direction of the eyeglass frame is enlarged, in Figure 5BThe horizontal direction of the eyeglass frame is enlarged. The first light guide plate 122 is a flat plate having an incident reflecting surface 130 that reflects image light into its interior and two main parallel planes (131, 132) that enclose the image light by total internal reflection. Inside, it has an outgoing reflecting surface group 133 containing two or more outgoing reflecting surfaces that emit image light out of the first light guide plate. The spacing between adjacent mirrors in the outgoing reflecting surface group 133 is L1. The second light guide plate 123 is a flat plate having an incident reflecting surface 140 (input section) that reflects image light into its interior and two main parallel planes (141, 142) that enclose the image light by total internal reflection. Inside, it has an outgoing reflecting surface group 143 (output section) containing two or more outgoing reflecting surfaces that emit image light out of the second light guide plate. The spacing between adjacent mirrors in the outgoing reflecting surface group 143 is L2. The second light guide plate 123 emits an image toward the user's pupil 20. Thus, in the virtual image generation unit 101 of this embodiment, the first light guide plate 122 and the second light guide plate 123 each have a set of parallel main surfaces that enclose the image light through internal reflection. The first light guide plate 122 has an incident reflection surface 130 that reflects the image light inward and two or more exit reflection surfaces that emit image light toward the second light guide plate 123. The incident reflection surface 130 and the exit reflection surfaces are parallel to each other and at an angle different from the main surfaces. The second light guide plate 123 has the aforementioned input section that couples the image light from the first light guide plate 122 inward and the aforementioned output section that emits the image light toward the user's pupil 20.

[0070] The following example illustrates the case of total internal reflection based on two parallel planes. However, it does not necessarily have to be total internal reflection. For example, a light guide plate that produces positive reflection or diffuse reflection can be used by attaching a thin film of a material that allows light to pass through or reflect to part or all of the parallel planes of the light guide plate that constitutes these parallel planes.

[0071] The emitting reflective surface group 133 of the first light guide plate 122 and the emitting reflective surface group 143 of the second light guide plate 123 are groups of partially reflective surfaces (an example of emitting reflective surfaces) that reflect a portion of light and transmit or absorb a portion of light, and these partially reflective surfaces are arranged in an array. By making the arrangement direction of the emitting reflective surface group 133 of the first light guide plate 122 different from the arrangement direction of the emitting reflective surface group 143 of the second light guide plate 123, the two-dimensional expansion of the eyeglass frame is achieved. Therefore, the lens aperture of the image display unit 120 and the projection unit 121 can be reduced (by increasing the F-value), and the virtual image generation unit 101 can be significantly miniaturized. Furthermore, in the first light guide plate 122 and the second light guide plate 123, partially reflective surfaces can be formed by reflecting mirrors, which are sometimes referred to as partially reflecting mirrors in this specification.

[0072] Figure 6 (A) represents an example of an image light copying element 300 that does not have a total internal reflection sealing function. Although light rays are emitted from the projection section 121 at a predetermined field of view, there is a problem that the shape becomes larger in order to prevent stray light from the side of the image light copying element 300. Figure 6 In the case of (B) being the first light guide plate 122 or the second light guide plate 123, the following advantages are available: since the image light is sealed by total internal reflection, the size of the components can be reduced, and the image light can be replicated to enlarge the eyeglass frame.

[0073] From an image quality perspective, it is preferable that the outgoing reflective surface group 133 of the first light guide plate 122 is parallel to each other to prevent angular shift of the reflected image light. That is, it is preferable that some of the reflective surfaces (outgoing reflective surfaces) of the outgoing reflective surface group 133 are parallel to each other. Similarly, it is preferable that the outgoing reflective surface group 143 of the second light guide plate 123 is also parallel to each other. That is, it is preferable that some of the reflective surfaces (outgoing reflective surfaces) of the outgoing reflective surface group 143 are parallel to each other. If the parallelism is reduced, the angle of the reflected light from the outgoing reflective surface group 133 or the outgoing reflective surface group 143 will differ among the reflective surfaces, resulting in stray light and image quality degradation.

[0074] Furthermore, if the incident reflective surface 130 of the first light guide plate 122 is also parallel to the exit reflective surface group 133, the processing steps are simplified, and manufacturing costs are reduced. This is because by stacking and bonding the flat plates with each reflective film made into a single unit and then cutting them out, the process from the incident reflective surface to the exit reflective surface can be completed simultaneously, and multiple first light guide plates 122 can be cut out based on this. When the angle of the incident reflective surface 130 is different, it is necessary to cut out the light guide plate and then cut the incident reflective surface to a specified angle before film is formed on the incident reflective surface. The incident reflective surface 140 of the second light guide plate 123 is also parallel to the exit reflective surface group 143, thereby simplifying processing and reducing costs.

[0075] Furthermore, from the viewpoint of stray light, it is preferable that the image light reflected by the outgoing reflective surface group 133 of the first light guide plate 122 is below the critical angle relative to the main parallel planes (131, 132) over the entire field of view before being emitted to the outside of the first light guide plate 122. This is because if there is a component exceeding the critical angle in the image light reflected by the outgoing reflective surface group 133, and this light propagates internally after reflection due to the sealing effect of the light guide plate, it will be reflected again by the outgoing reflective surface group 133 and become stray light, which will then be output to the second light guide plate 123. Similarly, from the viewpoint of avoiding stray light, it is preferable that the image light reflected by the outgoing reflective surface group 143 of the second light guide plate 123 is below the critical angle relative to the main parallel planes (141 and 142) over the entire field of view before being emitted to the outside of the second light guide plate 123.

[0076] The geometric conditions for the tilt angle θ of the exiting reflector and the critical angle of total internal reflection are explained in more detail. The exiting reflector of the exiting reflector assembly 133 has a specified tilt angle θ relative to the principal surfaces (131, 132) which are parallel planes, in order to change the direction of the image light and direct it outwards through the guide plate. Figure 7 In the diagram, the solid line (A) represents the ray at the center of the field of view, and the one-dash line (B) and two-dash lines (C) represent the rays at the ends of the field of view. Ray A at the center of the field of view, after reflection at the incident reflecting surface 130, needs to travel with an incident angle of 2θ relative to parallel planes 131 and 132. Furthermore, considering refraction at the incident surface 131, the incident angles of rays B and C within the light guide plate relative to planes 131 and 132 are in the range of 2θ ± arcsin[sin(Φ / 2) / n]. From the perspective of avoiding stray light, the incident angle of ray B relative to planes 131 and 132 needs to be 2θ + arcsin[sin(Φ / 2) / n] < 90° or less. Additionally, to satisfy the total internal reflection condition, the incident angle of ray C at planes 131 and 132 needs to be 2θ - arcsin[sin(Φ / 2) / n] < the critical angle or less. Here, n is the refractive index of the substrate. Typically, n is around 1.5. With a display field of view of around 30°, the tilt angle θ between the incident reflective surface 130 and the exit reflective surface group 133 is in the range of 16° to 40°.

[0077] The same condition must also be met in the second light guide plate 123, where the tilt angle θ between the incident reflective surface 140 and the exit reflective surface group 143 is in the range of 16° to 40°.

[0078] The above, such as Figure 5A , 5B As shown, since the second light guide plate 123 receives the image light emitted from the first light guide plate 122, the main surfaces (131, 132) of the first light guide plate 122 and the main surfaces (141, 142) of the second light guide plate 123 are located in different planes. The main surfaces (131, 132) of the first light guide plate are positioned closer to the projection section 121 than the main surfaces (141, 142) of the second light guide plate 123. The main surfaces (131, 132) and (141, 142) of the second light guide plate 123, which are their respective main parallel planes, are arranged parallel to each other. In addition, in order for the incident reflection surface 140 of the second light guide plate 123 to efficiently receive the image light emitted from the main surface 132 of the first light guide plate 122, the first light guide plate 122 and the second light guide plate 123 need to be close to each other.

[0079] Image light within the first light guide plate 122 is gradually reflected by a portion of the reflective surfaces of the outgoing reflective surface group 133, reducing the amount of light as it travels internally. Finally, all the image light is output to the second light guide plate 123 at the final surface 133-F of the outgoing reflective surface group 133, thereby improving light utilization efficiency. Therefore, as an example, by employing a structure where the reflectivity of the partial reflective surfaces of the outgoing reflective surface group 133 gradually increases from the side closest to the incident reflective surface 130 towards the final surface 133-F, the uniformity of the image light within the eyeglass frame is improved.

[0080] Here, while maintaining the see-through properties of the head-mounted display, the reflectivity of the emission reflective surface group 143 of the second light guide plate 123 is lower than that of the emission reflective surface group 133 of the first light guide plate 122. In this case, since the reflectivity in the emission reflective surface group 143 is low, even if the reflectivity of all the emission reflective surface groups 143 is the same (i.e., even if the same reflective film is used in each part of the reflective surface), it will not become a major factor in brightness unevenness. On the contrary, since each part of the reflective surface can be processed in the same film-forming process, manufacturing costs can be reduced. Furthermore, from the viewpoint of ensuring both brightness uniformity and see-through properties, the reflectivity of the emission reflective surface group 143 of the second light guide plate 123 is preferably 10% or less.

[0081] On the other hand, when light utilization efficiency is valued more than perspective (i.e., when reflectivity is set higher), for example, by gradually increasing the reflectivity of the reflective film of the outgoing reflective surface group 143 from the side close to the incident reflective surface 140, the uniformity of the amount of image light in the eyeglass frame is improved, and the image quality is enhanced.

[0082] When the spacing L1 between adjacent reflectors in the first light guide plate 122's exit reflective surface group 133 and the spacing L2 between adjacent reflectors in the second light guide plate 123's exit reflective surface group 143 are wider than the aperture P of the projection lens's exit section, the overlap between adjacent replicated image lights becomes insufficient, resulting in eyeglass frame areas with low image light intensity. Therefore, by making the spacing L1 and L2 between adjacent reflectors smaller than the aperture P of the projection section 121, the brightness uniformity within the eyeglass frame and the visually recognized image is improved.

[0083] Figure 8 is a structural diagram of a modified example where the incident reflection surface 140 of the second light guide plate 123 is not a reflection surface but an incident transmission surface 145 (input section). Figure 8A , 8B These respectively illustrate the cases where the virtual image generation unit 101 is positioned on the top of the head and on the side of the head. For example... Figure 8AAs shown, the image light emitted from the first light guide plate 122 is input to the incident transmission surface 145 of the second light guide plate 123 via the optical path correction prism 150. According to this structure, the width of the first light guide plate projected onto the Y-axis can be reduced, and the portion equivalent to dimension A can be reduced in appearance, improving design flexibility.

[0084] As described above, in terms of processing simplification, the incident transmission surface 145 is parallel to the partial exit reflection surface group 143, with tilt angles of θ relative to the main surfaces (141, 142). On the exit reflection surface side (i.e., the main surface 132 of the first light guide plate 122), the 2θ ray angle changes relative to the tilt angle θ, and in contrast, this changes in the incident transmission surface 145, resulting in image distortion. Therefore, as... Figure 8A , Figure 8B As shown, a light path correction prism 150 with a apex angle having the same angle as the tilt angle θ is used to correct the light path. Therefore, in FIG8, the main surfaces (131, 132) of the first light guide plate 122 are configured to be tilted by 2θ relative to the main surfaces (141, 142) of the second light guide plate 123. As described above, from the viewpoint of stray light, the tilt angle θ is in the range of 16° to 40°.

[0085] HMDs (Hardware-Modified Devices) have high requirements for the design of the eyeglass shape. Figure 8A , Figure 8B In the structure, the image display unit 120, the projection unit 121 and the first light guide plate 122 are tilted together, which also has the following advantages: the second light guide plate 123 can be easily arranged between the first light guide plate 122 and the user's pupil 20, and the HMD design in the shape of glasses is easy.

[0086] As described above, according to this embodiment, an HMD that balances miniaturization of the optical system and enlargement of the eyeglass frame can be provided.

[0087] Example 2

[0088] Figure 9 Arrows indicate the optical path when the light guide plate in Embodiment 1 is combined with the projection unit 121 that displays an image with a wide field of view. Image light with a predetermined field of view input to the incident reflection surface 130 of the first light guide plate 122 propagates in different directions within the light guide plate at each field of view, thus resulting in different output positions from the exit reflection surface group 133 to the second light guide plate 123. In particular, the image light exiting from the final surface 133-F, which is furthest from the incident reflection surface 130, has a significantly different exit position depending on the field of view. The wider the field of view of the image light, the greater the deviation of this exit position. Therefore, to avoid vignetting of these image lights, it is considered that, for example, in… Figure 9 In some configurations, the Y-axis direction of the light guide plate is increased, or the size of the components is increased, which increases the cost of manufacturing the components, or the size of the HMD is increased, which reduces the design flexibility as a wearable device.

[0089] As a larger issue, coupling is difficult at the incident and reflecting surface 140 of the finite-sized second light guide plate 123, resulting in reduced image brightness uniformity or decreased light utilization efficiency. Figure 9 In the diagram, arrows indicate the approximate optical paths of the field of view at the four corners of the displayed image (virtual image). The field of view output from the exiting reflector group 133, which is farther from the incident reflector 130 (also known as the side farther from the incident reflector 130 in the virtual image), is shown. Figure 9 In the configuration shown, the field of view 8 and the field of view 6 are output from the exiting reflective surface group 133 of the incident reflective surface 130 which is far away from the first light guide plate 122. Therefore, the deviation of the output position of the second light guide plate 123 relative to the incident reflective surface 140 is increased, making it difficult to couple with the second light guide plate 123.

[0090] Figure 10A , 10B This is a structural diagram of the light guide plate in this embodiment. Figure 10A , 10B In the middle, to and Figure 5A , 5B The same structure is labeled with the same symbol, and its description is omitted. Figure 10A , 10B These respectively illustrate the cases where the virtual image generation unit 101 is positioned on the top of the head and on the side of the head. Figure 10A , Figure 10B In, with Figure 5A , Figure 5B The difference lies in the orientation and arrangement of the incident reflective surface 140, the incident reflective surface 140 and the outgoing reflective surface group 143, which are provided with multiple second light guide plates 123.

[0091] The structure of the second light guide plate 123 in this embodiment will be described. As described above, within the first light guide plate 122, image light propagates extensively according to the field of view and exits from each of the exiting reflective surface groups 133. Therefore, the incident reflective surface 140 of the second light guide plate 123, which couples the image light from the first light guide plate 122, also needs a specified width. Here, when the light guide plate is thickened to increase the area of ​​the incident reflective surface 140 of the second light guide plate 123, the interval of total internal reflection of the image light enclosed inside becomes wider, the exit interval of the replicated image light becomes wider, and brightness unevenness is generated. In addition, an increase in weight and manufacturing cost is also generated due to the increase in thickness.

[0092] As a method to improve the coupling efficiency of image light from the first light guide plate 122 without increasing the thickness of the second light guide plate 123, one method is to set the incident surface to have two or more incident reflection surface groups 140'. By setting multiple incident surfaces, the effective area of ​​the incident surface can be increased without increasing the thickness. Here, FIG10 shows an example of an incident surface group 140' with three incident surfaces 140'-1 to 140'-3. In addition, the structure of the incident reflection surface group 140' can also improve the coupling efficiency of image light in the peripheral area of ​​the field of view when used in the second light guide plate 123 shown in FIG5 of Embodiment 1.

[0093] To maintain the image quality of the image light, it is preferable that the surfaces of the incident reflection surface group 140' are parallel. Furthermore, the image light reflected from the incident reflection surface 140'-1 needs to be transmitted through surfaces 140'-2 and 140'-3. Therefore, the incident reflection surface 140'-1 has a reflectivity close to 100%, and the closer it is to the pupil 20, the lower the reflectivity and the higher the transmittance.

[0094] Generally, when a reflective film is formed from a dielectric multilayer film, the reflectivity of s-polarized light increases. Therefore, the image light propagating in the first light guide plate 122 increases in p-polarized light as it moves towards the terminal portion of the exiting reflective surface group 133. This is observed from the incident reflective surface group 140' of the second light guide plate, where the s-polarized light component increases further towards the terminal portion of the exiting reflective surface group 133. Therefore, by forming the reflective film of the incident reflective surface group 140' of the second light guide plate 123 into a film with polarized light characteristics, and adjusting the reflectivity or transmittance characteristics accordingly to polarized light, the brightness uniformity of the displayed image can be improved.

[0095] As described above, the structure of the second light guide plate 123, which forms the incident reflective surface group 140', can improve the coupling efficiency at the periphery of the field of view and improve the brightness uniformity of the image. However, the overall brightness (light utilization efficiency) of the image decreases as unwanted reflections occur with the increasing number of reflective surfaces. Therefore, it is preferable to minimize the number of incident surface groups 140'. To this end, it is necessary to reduce the positional deviation of the image light emitted from the first light guide plate 122 at each field of view.

[0096] Therefore, in this embodiment, the structure rotates the incident reflective surface group 140' and the exit reflective surface group 143 of the second light guide plate 123 by a predetermined angle. By rotating the incident reflective surface group 140' and the exit reflective surface group 143, the light path within the second light guide plate 123 can also be rotated. According to this structure, the field of view (field of view angles 8 and 6 in the figure), which is the main reason for increasing the size of the first light guide plate 122 and increasing the number of reflective surfaces of the incident reflective surface group 140' of the second light guide plate 123, can be rotated within the light path of the second light guide plate 123. Therefore, according to this structure, the exit position from the first light guide plate 122 at this field of view (field of view angles 8 and 6 in the figure) can be brought closer to the incident reflective surface 130 side. Therefore, according to this structure, the size of the first light guide plate 122 is miniaturized, and the positional deviation of the image light emitted from the first light guide plate 122 at each field of view is reduced, and the number of reflective surfaces in the incident reflective surface group 140' of the second light guide plate 123 is reduced. This allows for improved light utilization efficiency of the second light guide plate 123 and reduced manufacturing costs.

[0097] Therefore, if the arrangement direction of the reflective surfaces of the outgoing reflective surface group 133 of the first light guide plate 122 is set as the first arrangement axis, and the arrangement direction of the reflective surfaces of the incoming reflective surface group 140' and the outgoing reflective surface group 143 of the second light guide plate 123 is set as the second arrangement axis, then by setting the angle between the first arrangement axis and the second arrangement axis to less than 90°, the size of the first light guide plate 122 can be miniaturized, and the number of reflective surfaces of the incoming reflective surface group 140' of the second light guide plate 123 can be suppressed.

[0098] In other words, the arrangement direction of the reflective surfaces of the outgoing reflective surface group 133 of the first light guide plate 122 is also the image light replication direction, so it is used as the first replication axis. The arrangement direction of the reflective surfaces of the incident reflective surface group 140' and the outgoing reflective surface group 143 of the second light guide plate 123 is also the image light replication direction, so it is used as the second replication axis. The angle between the first replication axis and the second replication axis is less than 90°. However, from the viewpoint of miniaturizing the size of the first light guide plate 122 and reducing the number of reflective surfaces of the incident reflective surface group 140' of the second light guide plate 123, it is preferable.

[0099] Relative to the image light at the aforementioned field of view Φ, the rotation angle of the incident reflecting surface group 140' and the exit reflecting surface group 143 of the second light guide plate 123 is Δ (i.e., in this example, the angle relative to the end face of the second light guide plate 123 is Δ), and the refractive index of each light guide plate is n. Here, as an example, the condition for preventing the light rays at the field of view 8 input from the incident surface from propagating within the first light guide plate to a position farther than the pupil 20 is Δ < arcsin((sinΦ / 2n) / 2). Here, assuming the refractive index n is approximately 1.5 and the field of view Φ is in the range of approximately 20° to 60°, the rotation angle Δ is preferably within the range of 10° or less. Therefore, it is preferable to set the angle between the first arrangement axis / replication axis and the second arrangement axis / replication axis to be 80° or more and less than 90°.

[0100] The tilt angles (i.e., tilt angles relative to the principal surface) of the exit reflecting surfaces of the first light guide plate 122 and the second light guide plate 123 will be explained. If the critical angle of total internal reflection, the condition of avoiding the inverted image caused by total internal reflection, and the condition of the light guide plate breaking the critical angle after reflection from the exit surface are taken into account, then, similar to Embodiment 1, the tilt angle θ is in the range of 16° to 40°.

[0101] Furthermore, the above has been described using the structure in which the second arrangement axis or the copy axis is rotated by the second light guide plate 123 as an example. However, even if the first arrangement axis or the copy axis of the first light guide plate 122 is rotated, the same effect can be obtained if the angle between the first arrangement axis / copy axis and the second arrangement axis / copy axis is less than 90°.

[0102] Figure 11 is a structural diagram of a modified example where the incident reflecting surface 140 of the second light guide plate 123 is not a reflecting surface but an incident transmitting surface 145. By rotating the incident reflecting surface 130 of the first light guide plate 122 and the exit reflecting surface of the exit reflecting surface group 133, the angle between the first arrangement axis / replication axis of the main surface 123 of the first light guide plate 122 and the second arrangement axis / replication axis of the reflecting surface of the exit reflecting surface group 143 of the second light guide plate 123 is less than 90°. With this structure, the coupling efficiency of the image light coupled from the first light guide plate 122 to the second light guide plate 123 in the region away from the incident reflecting surface 130 is improved. Figure 11A , Figure 11BFigures 8 and 11 illustrate the cases where the virtual image generation unit 101 is positioned on the top of the head and on the side of the head, respectively. As shown in Figures 8 and 11, the image light emitted from the first light guide plate 122 is input to the incident transmission surface 145 of the second light guide plate 123 via the optical path correction prism 150. This structure reduces the width of the first light guide plate projected onto the Y-axis, resulting in a smaller portion of the area equivalent to dimension A, thus improving design flexibility. In Figure 11, a structure in which the first alignment axis or replication axis is rotated via the first light guide plate 122 is described as an example. However, even if the second alignment axis or replication axis of the second light guide plate 123 is rotated, the same effect can be achieved if the angle between the first alignment axis / replication axis and the second alignment axis / replication axis is less than 90°.

[0103] As described above, in terms of processing simplification, the incident transmission surface 145 is parallel to the partial reflective surface group 143, with tilt angles of θ relative to the main surfaces (141, 142). On the exit reflective surface side (i.e., the main surface 131), the 2θ ray angle changes relative to the tilt angle θ, which in turn becomes a change in the amount θ in the incident transmission surface 145, resulting in image distortion. Therefore, as... Figure 11A , Figure 11B As shown, the optical path is corrected by a light path correction prism 150 with a apex angle having the same angle as the tilt angle θ. Therefore, in FIG11, the main surface (132) of the first light guide plate 122 is configured to be tilted by 2θ relative to the main surfaces (141, 142) of the second light guide plate 123. As described above, from the viewpoint of stray light, the tilt angle θ is in the range of 16° to 40°.

[0104] Figure 12 This is a schematic diagram illustrating the incident and reflection of light onto the reflecting surfaces within the first light guide plate 122 and the second light guide plate 123. Image light with a defined field of view within the first light guide plate 122 and the second light guide plate 123 is incident on the exit surface group within a defined angle range and output outside the light guide plate (normal reflection). On the other hand, since the light is confined within the light guide plate, reflected light is generated due to incident light from the back of the reflecting surface group (133, 140, 143) (back reflection). This back reflection is unwanted and is a major cause of stray light generation and reduced efficiency.

[0105] Based on the geometric configuration, the incident angle of the outgoing reflective surface group (133, 143) relative to the reflective surface is θ±arcsin[sin(Φ / 2) / n] under normal reflection and 3θ±arcsin[sin(Φ / 2) / n] under back reflection. Therefore, it is ideal to form a reflective film that suppresses back reflection in angle regions where the incident angle is larger than that of normal reflection, thereby reducing stray light and improving the light utilization efficiency of the light guide plate.

[0106] However, when a reflective film is formed by a dielectric multilayer film, the reflectivity of light with a large incident angle tends to increase. If the film structure is made more complex in order to suppress this, the total number of films increases, and the manufacturing cost increases.

[0107] Within the angular range of back reflection, the light rays on the side with the larger incident angle are output from the first light guide plate 122 between the incident reflecting surface (130) and the pupil 20 (in Figure 9 In the example shown in the diagram, the light rays correspond to those from field angles 5 and 7. The same light rays are also output in the second light guide plate 123 between the incident reflecting surface (140) and the pupil (in...). Figure 9 In the example shown in the diagram, the light rays are related to the field of view angles 5 and 6. Here, regarding the light output from the front half of the outgoing reflector group (133) and the light output from the front half of the outgoing reflector group (143) for coupling with the pupil 20, even if the reflectivity of the back reflection increases, the effects of light utilization efficiency and brightness unevenness are small.

[0108] Therefore, even if there are regions with higher reflectivity than normal reflection within the large incident angle range of back reflection, the structure and total number of dielectric multilayer films can be simplified without significantly impacting image quality, thus reducing manufacturing costs. In particular, the impact is minimal up to the center of the field of view; even if there are regions with higher reflectivity than normal reflection from the center of the back reflection angle range to the side with the large incident angle, it will not significantly affect image quality, simplifying the structure and total number of dielectric multilayer films and reducing manufacturing costs.

[0109] The structure of the reflective film related to back reflection described so far can be applied to the first light guide plate and the second light guide plate in all embodiments described so far to achieve the same effect.

[0110] Because the image light incident on the first light guide plate 122 propagates at different angles internally, the period of total internal reflection also varies for each field of view. The field of view output from the side of the first light guide plate 122 closer to the incident reflection surface 130 is larger (in... Figure 9In the example shown in the diagram (field angles 5 and 7), the larger the incident angle relative to the principal surfaces (131 and 132), the longer the total internal reflection period. This widens the image light replication interval, becoming a major cause of reduced brightness uniformity. Therefore, regarding the arrangement spacing of the outgoing reflective surfaces in the outgoing reflective surface group 133 of the first light guide plate 122, by setting the spacing of the reflective surfaces closer to the incident reflective surface 130 to be narrower than the spacing of the reflective surfaces closer to the center of the outgoing reflective surface group 133, brightness uniformity is improved. Furthermore, when observing the outgoing reflective surfaces of the first light guide plate 122 from the user's pupil 20, according to geometric relationships, the spacing between adjacent outgoing reflective surfaces appears wider on the side of the outgoing reflective surface group 133 closer to the incident reflective surface 130, thus also becoming a major cause of reduced brightness uniformity. Therefore, regarding this viewpoint, and also regarding the arrangement spacing of the outgoing reflective surfaces in the outgoing reflective surface group 133 of the first light guide plate 122, by setting the spacing of the reflective surfaces on the side closer to the incident reflective surface 130 to be narrower than the spacing of the reflective surfaces in the center of the outgoing reflective surface group 133, the brightness uniformity is improved.

[0111] The same applies to the second light guide plate 123. Since the image light incident on the second light guide plate 123 propagates at different angles internally, the period of total internal reflection also varies for each field of view. The closer the field of view (in the illustrated example, field of view angles 5 and 6) is to the side of the second light guide plate 123 closest to the incident reflecting surface (140), the larger the incident angle relative to the main surfaces (141 and 142), and the longer the total internal reflection period. This widens the image light replication interval, becoming a major cause of reduced brightness uniformity. Therefore, regarding the arrangement spacing of the exit reflecting surface group 143 of the second light guide plate 123, by setting the spacing of the reflecting surfaces on the side closest to the incident reflecting surface 140 to be narrower than that at the center of the exit reflecting surface group 143, brightness uniformity is improved. Furthermore, when observing the emitting reflective surface of the second light guide plate 123 through the user's pupil 20, according to geometric relationships, the spacing between adjacent emitting reflective surfaces appears wider on the side of the emitting reflective surface group 143 near the incident reflective surface 140. This is a major reason for the reduced brightness uniformity. Therefore, regarding this point, and also regarding the arrangement spacing of the emitting reflective surfaces in the emitting reflective surface group 143 of the second light guide plate 123, by setting the spacing of the reflective surfaces on the side near the incident reflective surface 140 to be narrower than the spacing of the reflective surfaces in the center of the emitting reflective surface group 143, brightness uniformity is improved.

[0112] The first light guide plate 122 and the second light guide plate 123 from the projection section 121 to the user's pupil 20 are geometrically configured as follows: the main surfaces of the first light guide plate 122 and the second light guide plate 123 are approximately parallel to each other, the main surfaces (131, 132) of the first light guide plate 122 and the main surfaces (141, 142) of the second light guide plate 123 are located in different planes, and the main surfaces (131, 132) of the first light guide plate 122 are arranged on the side closer to the projection section 121 than the main surfaces (141, 142) of the second light guide plate 123.

[0113] Typically, in order to confine wide-angle image light within a light guide plate, the substrate material needs to be made to have a high refractive index, reduce the critical angle of total internal reflection, and increase the range of light angles that can be confined.

[0114] When the image display unit 120 uses a microdisplay, the aperture P of the projection unit 121 is approximately 3 to 6 millimeters in size. In order to efficiently receive image light, the size of the incident reflective surface 130 and the incident reflective surface group 140' is also preferably approximately 3 to 6 millimeters. In addition, when the image display unit 120 is a laser scanning type such as a MEMS or fiber optic scanning device, the beam diameter is small and the aperture P of the projection unit is approximately 2 millimeters, which is relatively small. Therefore, the size of the incident reflective surface 130 and the incident reflective surface group 140' can also be miniaturized, and the thickness of the first light guide plate 122 and the second light guide plate 123 can also be reduced to suppress the increase in weight.

[0115] This concludes the explanation of the structure using a mirror array in the first light guide plate 122 and the second light guide plate 123. However, the eyeglass frame can also be enlarged by using light guide plates of different types. For example, Figure 13 An example of a light guide plate using a diffraction grating and a volume hologram for the second light guide plate is shown. An input section 146 is provided in the second light guide plate 123. The input section 146, replacing the incident reflecting surface 140 and the incident transmitting surface 145, is a surface-embossed diffraction grating and a volume hologram, which deflects the direction of travel of the input image light and guides it into the light guide plate. Similarly, a surface-embossed diffraction grating and a volume hologram are formed in the output section 147. By deflecting a portion of the image light propagating within the light guide plate toward the pupil 20, the eyeglass frame is enlarged, and an image display is achieved. By designing the surface-embossed diffraction grating and volume hologram of the output section 147 to reduce the diffraction efficiency towards external light, the second light guide plate 123 is transparent. In this structure, from the viewpoint of miniaturizing the size of the first light guide plate 122 and improving the coupling efficiency, it is preferable that the angle between the image light replication direction of the first light guide plate 122, i.e., the first replication axis, and the image light replication direction of the second light guide plate, i.e., the second replication axis, is less than 90°.

[0116] As shown in this embodiment, even with wide field of view image light incident, it is possible to expand the eyeglass frame while suppressing the increase in the size of the light guide plate and displaying high-quality images.

[0117] Therefore, according to this embodiment, an HMD can be provided that achieves wide field of view image display while also miniaturizing the optical system and enlarging the eyeglass frame.

[0118] Example 3

[0119] In this embodiment, examples of HMD applications described in each embodiment will be explained. Figure 14 This is a diagram illustrating an example of HMD usage in this embodiment.

[0120] exist Figure 14 In the image (virtual image) display area 111 from HMD1, content is displayed within the user's field of vision. For example, it displays work steps 201 and attached figures 202, such as those for inspecting or assembling industrial equipment. Since the image display area 111 is limited, displaying these work steps 201 and attached figures 202 simultaneously results in small content and poor visual recognition. Therefore, by performing head tracking using an accelerometer to detect the orientation of the user's head and adjusting the displayed content accordingly, visual recognition is improved. That is, in... Figure 14 In the image display area 111, when the user is facing left, operation step 201 is displayed, but when the user is facing right, figure 202 is displayed in the image display area 111. It can be displayed as if there is a virtual image display area 112 that allows for visual confirmation of operation step 201 and figure 202 with a wide field of view.

[0121] As a result, visual recognition is improved, and user 2 can perform the work while simultaneously visually recognizing the work object (equipment, tools, etc.) and work instructions, thus enabling more reliable work and reducing errors.

[0122] Figure 15 This is a structural block diagram of the HMD in this embodiment. Figure 15 In this section, structures identical to those in Figure 1 are labeled with the same symbols, and their descriptions are omitted. Figure 15 The difference from Figure 1 is that a head tracking function has been added. That is, the image signal processing unit 103A of HMD1 includes a head tracking unit 103H. The head tracking unit 103H detects the direction of the user 2's head based on the information from the accelerometer 106H of the sensing unit 106A, and changes the displayed content according to the direction of the head.

[0123] Furthermore, HMDs are used both indoors and outdoors. Therefore, it is also necessary to adjust the brightness of the displayed image according to the brightness of the surrounding environment. As an example, an illuminance sensor 106M is mounted on the sensing unit 106A, and the brightness of the image displayed by the image signal processing unit 103A can be adjusted according to the output of the illuminance sensor 106M.

[0124] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and includes various modifications. For example, the functional structures of the HMD and the virtual image generation unit 101 described above are classified according to the main processing content for ease of understanding. The present invention is not limited to the method or name of the classification of constituent elements. The structure of the HMD and the virtual image generation unit 101 can also be classified into more constituent elements according to the processing content. In addition, it is also possible to classify them in a way that performs more processing with one constituent element.

[0125] Furthermore, the present invention can be applied not only to HMDs, but also to other image (virtual image) display devices having the structure of the virtual image generation unit 101 described in the various embodiments.

[0126] The rotation angles of the exiting reflective surface group 133, the incident reflective surface group 140', and the exiting reflective surface group 143, as described above, where the angle between the first and second replica axes is less than 90°, are merely one example and are not limited to the numerical values ​​of the angles described above. Alternatively, the angle between the first and second replica axes may be appropriately set to less than 90°, without using the main surface or end face of the light guide plate as a reference.

[0127] Furthermore, a portion of the structure of one embodiment can be replaced with the structure of another embodiment. Additionally, structures from other embodiments can be added to the structure of one embodiment. Furthermore, portions of the structure of each embodiment can be added to, deleted from, or replaced with other structures.

[0128] Symbol Explanation

[0129] 1. Head-mounted display (HMD)

[0130] 101 Virtual Image Generation Unit

[0131] 102 Control Department

[0132] 103 Image Signal Processing Department

[0133] 104 Electricity Supply Department

[0134] 105 Storage Division

[0135] 106 sensor unit

[0136] 107 Ministry of Communications

[0137] 108 Sound Processing Department

[0138] 109 Filming Department

[0139] 91-93 Input / Output Section

[0140] 111 Image Display Area

[0141] 112 Virtual image display area

[0142] 120 Imaging Display Unit

[0143] 121 Projection Section

[0144] 122 First Light Guide Plate

[0145] 123 Second light guide plate.

Claims

1. A head-mounted display that displays images within a user's field of vision, characterized in that, The head-mounted display includes: An image display unit that generates the image to be displayed; and The first light guide plate and the second light guide plate replicate the image light from the image display unit. The first light guide plate and the second light guide plate each have a set of parallel main surfaces that enclose the image light through internal reflection. The first light guide plate has an incident surface that reflects image light inward and two or more exiting reflective surfaces that emit image light outward toward the second light guide plate. The second light guide plate includes an input section that couples image light from the first light guide plate into the interior and an output section that emits image light toward the user's pupil. The angle between the image light replication direction of the first light guide plate and the image light replication direction of the second light guide plate is less than 90°, and the image light replication direction of the second light guide plate is inclined relative to the end face of the second light guide plate.

2. The head-mounted display according to claim 1, characterized in that, The incident surface and the outgoing reflective surface of the first light guide plate are parallel to each other and at an angle different from that of the main surface.

3. The head-mounted display according to claim 1, characterized in that, The output section of the second light guide plate consists of two or more partial reflectors. The same reflective film is formed on the two or more partial reflectors.

4. The head-mounted display according to claim 1, characterized in that, The exit reflective surface of the first light guide plate and the output section of the second light guide plate are partial reflectors. It has a first incident angle range and a second incident angle range, wherein the first incident angle range is the range within which image light of a defined field of view normally enters and exits the partial reflector, and the second incident angle range is the range within which image light enters the partial reflector from the back. The first incident angle range is smaller than the second incident angle range. In the region of reflectivity from the center of the second incident angle range to the high-angle side, there is a portion with a higher reflectivity than the first incident angle range.

5. The head-mounted display according to claim 1, characterized in that, The input section of the second light guide plate has one or more incident reflective surfaces, and the output section is an output reflective surface group containing two or more output reflective surfaces. The incident reflecting surface and the exit reflecting surface group are parallel to each other and at an angle different from that of the main surface.

6. The head-mounted display according to claim 1, characterized in that, The angle between the arrangement axis of the outgoing reflective surface of the first light guide plate and the arrangement axis of the outgoing reflective surface of the second light guide plate is less than 90°.

7. The head-mounted display according to claim 1, characterized in that, The farther away from the incident surface, the higher the reflectivity of the exiting reflective surface of the first light guide plate. The spacing between the reflective surfaces of the first light guide plate and the second light guide plate is smaller than the aperture diameter of the projection portion that projects the image light from the image display unit onto the first light guide plate.

8. The head-mounted display according to claim 1, characterized in that, The spacing between the outgoing reflective surfaces located on the side closest to the incident surface is narrower than the spacing between the outgoing reflective surfaces located at the center of the region of the first light guide plate.

9. The head-mounted display according to claim 1, characterized in that, The main surface of the first light guide plate is parallel to the main surface of the second light guide plate. The main surface of the first light guide plate and the main surface of the second light guide plate are in different planes. The main surface of the first light guide plate is positioned closer to the projection portion of the first light guide plate than the main surface of the second light guide plate.

10. The head-mounted display according to claim 1, characterized in that, The angle of inclination of the outgoing reflective surface relative to the main surfaces of the first and second light guide plates is a specified angle θ. The tilt angle θ is in the range of 16° to 40°.

11. The head-mounted display according to claim 1, characterized in that, The input section of the second light guide plate has one or more incident reflective surfaces with a film having polarization characteristics.

12. The head-mounted display according to claim 1, characterized in that, The input section of the second light guide plate is an incident transmission surface, and the output section is an outgoing reflection surface group containing two or more outgoing reflection surfaces. The incident transmission surface and the exit reflection surface group are parallel to each other and at an angle different from that of the main surface. A light path correction prism with a vertex angle θ is disposed between the first light guide plate and the second light guide plate. The main surface of the first light guide plate is configured to be inclined at 2θ relative to the main surface of the second light guide plate.

13. The head-mounted display according to claim 1, characterized in that, The input section of the second light guide plate is an incident transmission surface, and the output section is an outgoing reflection surface group containing two or more outgoing reflection surfaces. The incident transmission surface and the exit reflection surface group are parallel to each other and at angles different from the main surface. The angle between the axis obtained by projecting the image light replication direction of the first light guide plate onto the main surface of the second light guide plate and the image light replication direction of the second light guide plate is less than 90°.

14. The head-mounted display according to claim 1, characterized in that, have: The power supply department supplies electricity; The sensing unit detects the user's position and posture; The sound processing unit is responsible for inputting or outputting sound signals. as well as The control unit controls the power supply unit, the sensing unit, and the sound processing unit.

15. The head-mounted display according to claim 1, characterized in that, have: An accelerometer sensor detects the movement of the user's head; The head tracking unit changes the displayed content based on the user's head movements; The power supply department supplies electricity; The sound processing unit is responsible for inputting or outputting sound signals. as well as The control unit controls the acceleration sensor, the head tracking unit, the power supply unit, and the sound processing unit.

Images