This invention relates to a head mounted display that is worn on the user's head and displays image in the field of view.
Wearable devices such as head mounted display (hereinafter referred to as HMD) require not only display performance, such as good vision and visibility of images, but also a compact structure with excellent wearability.
A prior art document in the field of this technique is JP-A-2003-536102, which discloses an optical device comprising a flat substrate that allows light to pass through, optical means for coupling light into the substrate by means of an internal reflective whole, and a plurality of partially reflective surfaces possessed by the substrate, wherein the partially reflective surfaces are parallel to each other and not parallel for any edge of the substrate.
The optical system of an HMD has an image display unit equipped with an illumination unit that transmits light emitted by the light source unit to a small display unit, and a projection unit that projects the image light (imaginary image) generated by the image display unit. If the HMD is misaligned with the user's eyes, the screen will be cut off. Therefore, for example, the eye box can be enlarged by using a waveguide that constitutes the duplication unit. However, the eye box enlargement causes the optical system size to increase and the optical efficiency to decrease.
In the above JP-A-2003-536102, no consideration was given to these issues in balancing the eye box expansion of the optical system and the miniaturization of the HMD optical system.
The purpose of the present invention is to provide HMD that combine miniaturization of the optical system with expansion of the eye box.
The present invention, to give an example, is a head mounted display that displays image in the user's field of vision, includes a video display unit that generates the image to be displayed, a first waveguide and a second waveguide that duplicate the video light from the video display unit. each of the first waveguide and the second waveguide includes a pair of parallel main planes that confine video light by internal reflection, the first waveguide includes an incident surface that reflects video light into the inside and two or more outgoing reflective surfaces that emit video light into the second waveguide, the second waveguide includes an input unit that couples video light from the first waveguide to the inside and an output unit that emits video light to the user's pupil. The angle between the duplication direction of video light in the first waveguide and the duplication direction of video light in the second waveguide is less than 90°.
The present invention can provide HMD that combine miniaturization of the optical system with expansion of the eye box.
Following, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are illustrative examples to explain the invention, and have been omitted or simplified as appropriate for clarity of explanation. The invention can also be implemented in various other forms. Unless otherwise limited, each component can be singular or plural.
The position, size, shape, extent, etc. of each component shown in the drawings may not represent the actual position, in order to facilitate understanding of the invention. Therefore, the invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.
In the following explanations, various types of information may be described in terms of “tables,” “lists,” etc., but various types of information may be expressed in data structures other than these. XX table”, “XX list”, etc. may be called “XX information” to indicate that they do not depend on any data structure. When expressions such as “identification information,” “identifier,” “name,” “ID,” “number,” etc. are used when describing identification information, they can be substituted for each other.
When there are multiple components having the same or similar functions, the same numerals may be explained with different subscripts. However, when there is no need to distinguish between these multiple components, the subscripts may be omitted and explain.
In the following description, the processing performed by executing the program may be described, but the program is executed by the processor (e.g., CPU (Central Processing Unit), GPU (Graphics Processing Unit)) to perform prescribed processing while appropriately using storage resources (e.g., memory) and/or interface devices (e.g., communication ports). Therefore, the subject of processing may be the processor. Similarly, the subject of the processing performed by executing the program may be a controller, device, system, computer, or node having a processor. The processing subject that executes the program may be a processing unit, or it may be a dedicated circuit (e.g., FPGA (Field-Programmable Gate Array) or ASIC (Application Specific Integrated Circuit)) that performs specific processing.
The program may be installed on a device such as a computer from a program source. The program source may be, for example, a program distribution server or computer readable storage media. If the program source is a program distribution server, the program distribution server may include a processor and a storage resource that stores the program to be distributed, and the processor of the program distribution server may distribute the program to other computers. In the following description, two or more programs may be realized as one program, or one program may be realized as two or more programs.
Virtual image generation unit 101 displays augmented reality (AR) or mixed reality (MR) images in the view of the wearer (user) by magnifying and projecting the images generated by the small display unit as imaginary images.
Control unit 102 controls the HMD 1 as a whole, and its function is realized by an arithmetic device such as a CPU, etc. Image signal processing unit 103 supplies image signals used for display to the display unit in the virtual image generation unit 101. Electric power supply unit 104 supplies electric power to each part of HMD 1.
Memory unit 105 stores data necessary for processing in each part of HMD 1 and data generated in each part of HMD 1. Also, memory unit 105 stores programs and data to be executed by the CPU when the functions of control unit 102 are realized by the CPU. Memory unit 105 is configured by HDD (Hard Disk Drive), SSD (Solid State Drive), or other storage devices.
Sensing unit 106 is connected to various sensors via input/output unit 91, which is a connector, and detects the posture of HMD 1 (i.e., user posture, user head orientation), motion, ambient temperature, etc. based on signals detected by the various sensors. As various sensors, for example, a tilt sensor, acceleration sensor, temperature sensor, GPS (Global Positioning System) sensor to detect the user's position data, etc. are connected.
Communication unit 107 communicates with external data processing devices by short-range wireless communication, long-range wireless communication, or wired communication via input/output unit 92, which is a connector. Specifically, communication is performed via Bluetooth (registered trademark), Wi-Fi (registered trademark), mobile communication networks, universal serial bus (USB, registered trademark), high-definition multimedia interface (HDMI (registered trademark)), etc.
Audio processing unit 108 is connected to audio input/output devices such as microphones, earphones, and speakers via input/output unit 93, which is a connector, to input or output audio signals. Imaging unit 109 is, for example, a small camera or a small TOF (Time Of Flight) sensor, takes a picture of view direction of HMD 1 user.
CPU 201 is a microprocessor unit that controls the entire HMD 1. CPU 201 corresponds to control unit 102. The system bus 202 is a data communication path for sending and receiving data between the CPU 201 and each operating block in the HMD 1.
ROM 203 is a memory in which basic operating programs such as an operating system and other operating programs are stored, can be used a rewritable ROM, such as EEPROM (Electrically Erasable Programmable Read-Only Memory) and flash ROM.
RAM 204 serves as a work area during execution of the basic operating program and other operating programs. ROM 203 and RAM 204 may be an integral part of CPU 201. ROM 203 may also use a portion of the storage area in storage 210, rather than in an independent configuration as shown in
Storage 210 stores operating programs and operating settings of data processing device 100, personal information 210a of the user using HMD 1, and other information. Although not specifically exemplified below, storage 210 may also store operating programs downloaded from the network and various data created by the operating programs. Some storage areas of storage 210 may be substituted for some or all of the functions of ROM 203. For example, devices such as flash ROM, SSD, HDD, etc. may be used for storage 210. ROM 203, RAM 204, and storage 210 correspond to memory unit 105. The above operating programs stored in ROM 203 and storage 210 can be updated and functionally extended by executing a download process from each device on the network.
Communication processing apparatus 220 comprises a LAN (Local Area Network) communication device 221, a telephone network communication device 222, an NFC (Near Field Communication) communication device 223, and a BlueTooth communication device 224. Communication processing apparatus 220 corresponds to communication unit 107. In
Virtual image generation mechanism 225 has video display unit 120, projection unit 121, first waveguide 122, and second waveguide 123. The virtual image generation mechanism 225 corresponds to virtual image generation unit 101. The specific configuration of the virtual image generation mechanism 225 is described below using
Electric power supply device 230 is a power supply device that supplies power to HMD 1 in accordance with a specified standard. Electric power supply device 230 corresponds to electric power supply unit 104.
Video processor 240 comprises a display 241, an image signal processor 242, and a camera 243. Video processor 240 corresponds to image signal processing unit 103 and virtual image generation unit 101. Also, camera 243 corresponds to imaging unit 109. Display 241 corresponds to the small display unit described above.
Display 241 is a display device, for example, a liquid crystal display, digital micromirror device, organic EL display, micro LED display, MEMS (Micro Electro Mechanical Systems), fiber scanning device, displays image data processed by image signal processor 242. Image signal processor 242 displays the input image data on display 241. Camera 243 is camera unit functions as an imaging device that inputs image data of the surroundings and objects, by converting the light input from the lens into electrical signals by using an electronic device such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor.
Audio processor 250 comprises a speaker 251, an audio signal processor 252, and a microphone 253. Audio processor 250 corresponds to audio processing unit 108.
Speaker 251 outputs audio signals processed by audio signal processor 252. Audio signal processor 252 outputs input audio data to speaker 251. Microphone 253 converts voice into audio data and outputs it to audio signal processor 252.
Sensor 260 is a group of sensors for detecting the status of data processing device 100 and includes a GPS receiver 261, a gyro sensor 262, a geomagnetic sensor 263, an acceleration sensor 264, an illumination sensor 265, and a proximity sensor 266. The sensor 260 corresponds to the sensing unit 106.
HMD 1 is worn on the head of user 2, and the image generated by the virtual image generation unit 101 is propagated to the user's pupil 20 via the second waveguide 123. In this case, the user 2 can see the image (virtual image) in a part of the video display area 111 in the field of view in a state where the outside world is visible (see-through type). Although
Next, a conventional configuration diagram of a virtual image generation unit 101 using a mirror array type waveguide 123 is shown in
The eye box formed by the virtual image generation unit 101 should be expanded in the two-dimensional direction from the viewpoint of practicality. since the waveguide 123 expands the eye box only in the horizontal direction, the optical engine needs to input video light that a large light beam diameter in the vertical direction. Therefore, the F-number of the optical system of the video display unit 120 in the direction needs to be reduced, as a result, the size of dimension A of the video display unit 120 and projection unit 121 in (a) of
Thus, HMD has issue achieving both expanding the eye box in the two-dimensional direction and reducing the size. These solutions are described below.
In the following, the case in which the internal reflection is total reflection by two parallel planes is illustrated. However, it does not necessarily have to be total reflection. For example, a waveguide with parallel planes that produce normal reflection or diffuse reflection may be used by attaching a film made of a material that transmits or reflects light to some or all of the parallel planes of the waveguide that comprises these parallel planes.
The outgoing reflective surfaces 133 of the first waveguide 122 and the outgoing reflective surfaces 143 of the second waveguide 123 are group of partial reflective surfaces (an example of outgoing reflective surface) that reflect some light and transmit or absorb some light, and the partial reflective surfaces are arranged in an array. By the array direction of the outgoing reflective surfaces 133 of the first waveguide 122 and the array direction of the outgoing reflective surfaces 143 of the second waveguide 123 are different, the two-dimensional expansion of the eye box is realized. Therefore, the lens aperture of the video display unit 120 and projection unit 121 can be reduced (F-number can be increased), and the virtual image generation unit 101 can be made much smaller. In the first waveguide 122 and second waveguide 123, the partial reflective surfaces can be formed by a mirror, and this mirror is sometimes referred to a partial reflective mirror, in the specification.
The outgoing reflective surfaces 133 of the first waveguide 122 are desirable that parallel to each other to avoid angular misalignment of the reflected image light from the viewpoint of image quality. Thus, the partial reflective surface (outgoing reflective surface) of the outgoing reflective surfaces 133 are desirable that parallel to each other. Similarly, the outgoing reflective surfaces of the second waveguide 123 are desirable parallel to each other. Thus, the partial reflective surface (outgoing reflective surface) of the outgoing reflective surfaces 143 are desirable that parallel to each other. Here, if the parallelism is reduced, the ray angle after reflection at the outgoing reflective surfaces 133 or the outgoing reflective surfaces 143 differs for each reflection surface, degrading image quality by occurring stray light.
If the incident surface 130 of the first waveguide 122 and the outgoing reflective surfaces 133 are also parallel, the processing process can be simplified and manufacturing costs can be reduced. This is because the flat plates with each reflective film are stacked, bonded, and cut out, enabling processing from the incident surface to the outgoing reflective surface in one process, and also making it possible to cut out multiple pieces of first waveguide 122. If the angle of the incident surface 130 is different, it is necessary to cut out the waveguide, after the process of further cutting the incident surface to a predetermined angle, etc. and form the film on the incident surface. By the incident reflective surface 140 of the second waveguide 123 and the outgoing reflective surfaces 143 are parallel as well, it is possible that simplifying the processing and reducing costs.
From the viewpoint of stray light, the video light reflected on the outgoing reflective surfaces 133 of the first waveguide 122 is desirable emitted outside the first waveguide 122 less than or equal to the critical angle at all view angles relative to the main parallel planes (131, 132). This is because if the video light reflected on the outgoing reflective surfaces 133 has a component that exceeds the critical angle and continues to propagate inside the waveguide due to the confinement effect of the waveguide after reflection, this light will be reflected again on the outgoing reflective surfaces 133 and become stray light, output to the second waveguide 123. Similarly, from the viewpoint of avoiding stray light, it is desirable that the video light reflected from the outgoing reflective surfaces 143 of the second waveguide 123 be output to the outside of the second waveguide 123 at a critical angle or less at all view angles to the main parallel planes (141 and 142).
More detailed geometric conditions for the tilt angle θ of the outgoing reflective surface and the total reflection critical angle are described below. The output reflective surface of the outgoing reflective surfaces 133 has a predetermined inclination angle θ with respect to the main planes (131, 132) which are parallel planes in order to change the direction to output the video light to the outside of the waveguide. In
The same condition needs to be satisfied in second waveguide 123, and the tilt angle θ of the incident reflective surface 140 and the outgoing reflective surfaces 143 is in the range of 16° to 40°.
As described above, because the second waveguide 123 receives the video light emitted from the first waveguide 122, as shown in
The video light in the first waveguide 122 is gradually reflected by the partial reflective surfaces of the outgoing reflective surfaces 133, and proceeds through the interior while reducing the amount of light, and finally all the video light is output to the second waveguide 123 at the final surface 133-F of the outgoing reflective surfaces 133, thereby improving the light utilization efficiency. Therefore, as an example, by configuring the reflectance of the partial reflective surfaces of the outgoing reflective surfaces 133 to gradually increases from the side closer to the incident surface 130 to the final surface 133-F, the light intensity uniformity of the video light within the eye box is improved.
Here, when maintaining the see-through property as a head mounted display, the reflectance of the outgoing reflective surfaces 143 of the second waveguide 123 is lower than that of the outgoing reflective surfaces 133 of the first waveguide 122. In this case, because the reflectance at the outgoing reflective surfaces 143 is low, even if the reflectance of the outgoing reflective surfaces 143 is all the same (i.e., even if the same reflective film is used for each partial reflective surface), it will not be a causing of significant uneven brightness. Rather, since each partial reflective surface can be processed by the same film deposition process, manufacturing costs can be reduced. However, from the viewpoint of ensuring both luminance uniformity and see-through property, it is desirable that the reflectance of the outgoing reflective surfaces 143 of the second waveguide 123 be 10% or less.
On the other hand, if light utilization efficiency is more important than see-through property (i.e., if reflectance is set higher), as an example, by a configuration that the reflectance of the reflective film of the outgoing reflective surfaces 143 gradually increases from side closer to the input surface 140, the light intensity uniformity of video light in the eye box will be improved and image quality will be improved.
If the spacing L1 between adjacent mirrors in the outgoing reflective surfaces 133 of the first waveguide 122 and the spacing L2 between adjacent mirrors in the outgoing reflective surfaces 143 of the second waveguide 123 are wider than the aperture diameter P of the projection lens output section, an eye box area with a small amount of video light is generated by the overlap between adjacent duplicated video light is insufficient. Therefore, by making the spacing L1 and L2 of adjacent reflecting surfaces smaller than the aperture diameter P of the projection unit 121, the luminance uniformity within the visible image and the eye box are improved.
As mentioned above, for simplification of processing, the incident transmissive surface 145 and the partial reflective surfaces 143 are parallel, and their tilt angles with respect to the main surfaces (141, 142) are θ each. On the outgoing reflective surface side (i.e., the main surface 132 of the first waveguide 122), the ray angle changes by 2θ relative to the tilt angle θ, whereas on the incident transmissive surface 145, the angle changes by θ, resulting in distortion of the image. Therefore, as shown in
HMD is highly demanded for eyeglass-shaped design. the configuration of
As described above, this example provides an HMD that achieves both of the miniaturization of the optical system and the expansion of the eye box.
An even greater issue is that the finite size of the incident reflective surface 140 of the second waveguide 123 makes coupling difficult, resulting in reduced image luminance uniformity and light-utilization efficiency. In
The configuration of second waveguide 123 in this example is described. As mentioned above, video light propagates in the first waveguide 122 with a spread according to the angle of view and is emitted from each of the outgoing reflective surfaces 133. Therefore, the incident surface 140 of the second waveguide 123, which combines the video light from the first waveguide 122, also needs to have a certain width. Here, if the waveguide is made thicker to increase the area of the incident surface 140 of the second waveguide 123, the interval of total reflection of the video light confined inside becomes wider, and the outgoing interval of the duplicated video light becomes wider, resulting in uneven brightness. In addition, weight and manufacturing cost will also increase due to the increased thickness.
One method to increase the coupling efficiency of the video light from the first waveguide 122 without increasing the thickness of the second waveguide 123 is to use an incident surface group 140′ with two or more incident surfaces. By providing multiple incident surfaces, the effective area of the incident surface can be increased without increasing the thickness. Here,
To maintain the image quality of video light, it is desirable that the planes of the incident surface group 140′ are parallel to each other. The video light reflected from the incident surface 140′-1 need to pass through the surfaces 140′-2 and 140′-3. Therefore, the incident surface 140′-1 has a reflectance close to 100%, and the closer the surface is to the pupil 20, the lower the reflectance and the higher the transmission.
Generally, when a reflective film is formed with dielectric multilayers, the reflectance of s-polarized light is higher. Therefore, the video light propagating through the first waveguide 122 has more p-polarized components as it moves toward the end of the outgoing reflective surfaces 133. When viewed from the incident reflective surfaces 140′ of the second waveguide, the s-polarized component increases toward the end of the outgoing reflective surfaces 133. Therefore, by forming the reflective film of the incident reflective surfaces 140′ of the second waveguide 123 as a film with polarization characteristics, and adjusting the reflectance or transmittance characteristics in response to polarization, the luminance uniformity of the displayed image can be improved.
Above mentioned, the configuration of second waveguide 123 with the incident surfaces 140′ can improve the coupling efficiency at the periphery of the angle of view and increase the luminance uniformity of screen, but the luminance (light utilization efficiency) of the entire screen decreases as the number of reflecting surfaces increases, because unnecessary reflections are also generated. Therefore, it is desirable to minimize the number of the incident surfaces 140′, and for this purpose, it is necessary to reduce the amount of positional deviation of the video light emitted from the first waveguide 122 for each angle of view.
Therefore, in this example, the incident surfaces 140′ and the outgoing reflective surfaces 143 of the second waveguide 123 are rotated by a predetermined angle. By rotating the incident surfaces 140′ and the outgoing reflective surfaces 143, the light path in the second waveguide 123 can also be rotated. This configuration allows the size of the first waveguide 122 to be enlarged and to be rotate the light path in the second waveguide 123 of the angle of view (angle of view 8 and angle of view 6 in the figure) that is a factor the number of reflective surfaces in the incident surfaces 140′ of the second waveguide 123 to be increased. Therefore, this configuration can bring the emit position of the angle of view (angle of view 8 and 6 in the figure) from the first waveguide 122 closer to the incident surface 130 side. Therefore, the size of the first waveguide 122 is downsized and the amount of positional deviation of the video light emitted from the first waveguide 122 for each angle of view is reduced, and the number of reflective surfaces of the incident surfaces 140 of the second waveguide 123 is reduced. This can improve the light utilization efficiency of the second waveguide 123 and reduce the manufacturing cost.
Therefore, if the array direction of the reflective surfaces of the outgoing reflective surfaces 133 of the first waveguide 122 is the first array axis, and the array direction of the incident surfaces 140′ and the reflective surfaces of the outgoing reflective surfaces 143 of the second waveguide 123 is the second array axis, then by setting the angle formed by the first and second array axes to be less than 90°, the size of the first waveguide 122 can be smaller and a number of reflective surfaces of the incident surfaces 140′ of the second waveguide 123 can be reduced.
In other words, since the direction of the array of reflective surfaces of the outgoing reflective surfaces 133 of the first waveguide 122 is also the direction in which the video light is duplicated, this is the first duplication axis. since the direction of array of the reflective surfaces of the incident surfaces 140′ and the outgoing reflective surfaces 143 of the second waveguide 123 is also the direction in which the video light is duplicated, this is the second duplication axis. In this case, the angle formed by the first and second duplication axes be less than 90°, is desirable from the viewpoint of to reduce the size of the first waveguide 122, and to reduce the number of reflective surfaces of the incident surfaces 140′ of the second waveguide 123.
For the video light with the angle of view Φ described above, the angle of rotation of the incident surfaces 140′ and the outgoing surfaces 143 of the second waveguide 123 is Δ (i.e., in this example, the angle to the end face of the second waveguide 123 is Δ), and the refractive index of each waveguide is n. In this case, the condition for the light ray of the above angle of view 8 input from the incident surface not to propagate within the first waveguide to a position farther than pupil 20 is, as an example, Δ<arcsin((sin Φ/2n)/2). Here, assuming that the refractive index n is about 1.5 and the angle of view Φ is in the range of 20° to 60°, it is desirable that the rotation angle Δ is in the range of within 10°. Therefore, a configuration in which the angle formed by the first array axis/duplication axis and the second array axis/duplication axis is between 80° and 90° is desirable.
The tilt angle (i.e., the tilt angle with respect to the main plane) of the outgoing reflective surface of first waveguide 122 and second waveguide 123 is explained. Considering the total reflection critical angle, the condition to avoid inverted images due to total reflection, and the condition that to emit the critical angle is broken from the waveguide after the outgoing surface reflection, the tilt angle θ is in the range of 16° to 40°, as in Example 1.
Also, the configuration in which the second array axis or duplication axis is rotated by the second waveguide 123 has been described as an example. But, the same effect can be obtained by rotating the first array axis or duplication axis of the first waveguide 122, so that the angle formed by the first array axis/duplication axis and the second array axis/duplication axis is less than 90°.
As mentioned above, in terms of processing simplicity, the incident transmissive surface 145 and the group of partial reflective surfaces 143 are parallel, and the tilt angle with respect to the main planes (141, 142) is θ for each of them. On the outgoing reflective surface side (i.e., main plane 131), the ray angle changes by 2θ with respect to the tilt angle θ, whereas on the incident transmissive surface 145, the change is for θ, occurring in distortion of the image. Therefore, as shown in
From the geometric arrangement, the angle of incidence to the reflective surface of the outgoing reflective surfaces (133, 143) is θ±arcsin [sin (Φ/2)/n] when it is normal reflection and 3θ±arcsin [sin (Φ/2)/n] when it is back reflection. Therefore, it is ideal to form a reflective film that suppresses backside reflection in the angle region where the angle of incidence is larger than the angle region of normal reflection to reduce stray light and improve the light utilization efficiency of the waveguide.
However, in general, when reflective films are formed with dielectric multilayers, rays with large incident angles tend to have large reflectance, and if the film structure is complicated to suppress this, the total number of film increases and manufacturing costs rise.
Rays on the larger side of the angle of incidence within the angular range of backside reflection are output from first waveguide 122 between the plane of incidence (130) and pupil 20 (in the example illustrated in
Therefore, even if there is an area higher than the reflectance in the angular range of normal reflection in the reflectance characteristic on the side with a large incident angle within the angular range of backside reflection, the structure and total number of dielectric multilayer films can be simplified without significantly affecting the image quality, and the manufacturing cost can be suppressed. In particular, the effect is small in the range up to the center of the angle of view, and even if there is an area higher than the reflectance in the angular range of normal reflection in the reflectance on the side where the incident angle is large from the center within the angle range of the backside reflection, the structure of the dielectric multilayer film and the total number of films can be simplified without significantly affecting the image quality, and the manufacturing cost can be reduced.
The configuration of the reflective film for backside reflection described so far can be applied to the first and second waveguides in all the examples described so far, to achieve the same effect.
Since the video light incident on the first waveguide 122 propagates at different angles inside the first waveguide 122, the period of total reflection also changes for each angle of view. The angle of view output on the side closer to the incident surface 130 of the first waveguide 122 (angles of view 5 and 7 in the example illustrated in
This is also true for the second waveguide 123, where the video light incident on the second waveguide 123 propagates at different angles inside the second waveguide 123, and the period of total reflection also changes for each angle of view. The angle of view output on the side closer to the incident surface 140 of the second waveguide 123 (angles of view 5 and 6 in the example illustrated), the larger the angle of incidence to the main planes (141, 142) and the longer the total reflection period. This causes the video light duplication interval to widen, resulting in a decrease in luminance uniformity. Therefore, the luminance uniformity is improved, regarding the spacing of the outgoing reflective surfaces 143 of second waveguide 122, by setting the spacing of the reflective surfaces closer side to the incident surface 140 narrower than the center part of the outgoing reflective surfaces 143. In addition, when the outgoing reflective surfaces of second waveguide 123 are viewed from the user's pupil 20, in the outgoing reflective surfaces 143 of second waveguide 123 closer to the incident surface 140, the spacing between adjacent outgoing reflective surfaces appears wider due to geometric relationships, it is also factor that reduces luminance uniformity. Therefore, from this point of view, the luminance uniformity is also improved in the same way, regarding the spacing of the outgoing reflective surfaces in the outgoing reflective surfaces 143 of second waveguide 123, by setting the spacing of the reflective surfaces closer side to the incident surface 140 narrower than the spacing of the reflective surfaces in the center part of the outgoing reflective surfaces 143.
With respect to the geometrical arrangement of the first waveguide 122 and the second waveguide 123 from the projection unit 121 to the user pupil 20, the main planes of said first waveguide 122, the second waveguide 123, are roughly parallel to each other, and the main planes (131, 132) of the first waveguide 122 and the main planes (141, 142) of the second waveguide 123 are in different planes. The main surface (131, 132) of the first waveguide 122 is arranged closer to the projection unit 121 than the main planes (141, 142) of the second waveguide 123.
Normally, in order to confine video light with a wide angle of view within a waveguide, it is need to that increasing the angular range of light rays that can be confined, by raising the refractive index of the substrate material, and reducing the critical angle of total reflection.
When a microdisplay is used for the video display unit 120, the aperture diameter P of the projection unit 121 is about 3 to 6 mm, and to efficiently receive video light, it is desirable that the size of the incident reflective surface 130 and the incident reflective surfaces 140′ is also about 3 to 6 mm. When the video display unit 120 is a laser scanning type such as a MEMS or fiber scanning device, the beam diameter is small and the projection unit aperture diameter P is as small as ˜2 mm, so the size of the incident reflective surface 130 and the incident reflective surfaces 140′ can also be reduced, and the thickness of the first waveguide 122 and the second waveguide 123 is also thinner and the weight increase can be suppressed.
So far, we have described a configuration using mirror arrays for the first waveguide 122 and second waveguide 123, but the eye box may be expanded with a waveguide using a different method. For example,
As described above, by the configuration shown in this example, even when video light with a wide angle of view is input, enables high-quality images to be displayed by expanding the eye box while suppressing the increase in the size of the waveguide.
Therefore, according to this example, it is possible to provide an HMD that achieves both downsizing of the optical system and expansion of the eye box while achieving a wide-angle image display.
This example describes the application of the HMD described in each example.
In
This improves visibility and allows user 2 to execute work while simultaneously viewing the work object (equipment, tools, etc.) and work instructions, enabling more reliable work and reducing errors.
In addition, HMD are used indoors and outdoors. Therefore, it is necessary to adjust the luminance of the displayed image according to the brightness of the surrounding environment. As an example, the sensing unit 106A can be equipped with an illumination sensor 106M, and the brightness of the image displayed by the image signal processing unit 103A can be adjusted according to the output of the illumination sensor 106M.
Although the examples according to the present invention are described above, the present invention is not limited to the above examples but includes various variations. For example, the functional configuration of the HMD and virtual image generation unit 101 described above is classified according to the main processing contents for ease of understanding. The way the components are classified and their names do not limit the invention. The configuration of the HMD and virtual image generation unit 101 can be further classified into many components depending on the processing content. It can also be classified so that one component performs more processing.
It goes without saying that the invention can be applied not only to HMD but also to other video (virtual image) display apparatuses having the configuration of the virtual image generation unit 101 described in each example.
The angles of rotation of the outgoing reflective surfaces 133, the incident surfaces 140′, and the outgoing reflective surfaces 143 in the case where the angle formed by the first and second duplication axes is less than 90°, as explained above, are examples only and are not limited to the contents (angle values) explained above. The angle formed by the first and second duplication axes may be appropriately formed to be less than 90° without reference to the main plane or end face of the waveguide.
It is also possible to replace part of the configuration of one example with the configuration of another example. It is also possible to add the configuration of one example to the configuration of another example. Also, for a part of the configuration of each example, it is also possible to add/delete/replace other configurations.
Number | Date | Country | Kind |
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2021-024673 | Feb 2021 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2021/048706 | 12/27/2021 | WO |