WO2022064564A1

WO2022064564A1 - Head-mounted display

Info

Publication number: WO2022064564A1
Application number: PCT/JP2020/035821
Authority: WO
Inventors: 治川前; ニコラスサイモンウォーカー; ジャンジャスパーバンデンバーグ; 康宣橋本
Original assignee: マクセル株式会社
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2022-03-31

Abstract

A head-mounted display 1 comprises a focus-free image display part 7 for emitting a narrow-field focus-free image L1 to the substantial center of a display screen, a fixed-focus image display part 8 for emitting a wide-field fixed-focus image L2 to the display screen, and a control unit 2 for performing control so that the focus-free image and the fixed-focus image are positioned and simultaneously or alternately displayed. The present invention employs a retina-scanning-type optical system using a Maxwellian view optical system to display the focus-free image, and comprises a polarizing beam splitter 91 for reflecting image light L1 emitted from the focus-free image display part 7, and a transparent retroreflection plate 92 which has a transparent region in a portion thereof and retroreflects the image light L1, the retroreflected image light L1 passing through the polarizing beam splitter 91 and being incident on an eye 20 of the user.

Description

Head mounted display

The present invention relates to a head-mounted display that is mounted on the user's head and displays an image of virtual reality or augmented reality.

A head-mounted display (hereinafter, HMD: Head Mounted Display) worn on the user's head displays an image of virtual reality (VR: Virtual Reality) or augmented reality (AR: Augmented Reality) on a glasses-shaped display screen. It is something to do. Of these, in the case of an AR image, the spectacle-shaped display screen is made translucent, and the AR image is displayed on top of the object in the real space in front of the eyes while visually recognizing it.

The VR and AR images presented by the HMD generally have a fixed depth of focus. On the other hand, by using binocular stereoscopic vision, it is possible to present VR and AR objects at a distance different from the fixed display depth. At that time, the focus of the user's eye converges on the object, but the accommodation of the crystalline lens corresponding to the convergence of both eyes may not match. It is known that this disagreement in accommodation / accommodation (VA) causes discomfort to the user and causes so-called "VR sickness".

As a method of eliminating the VA disagreement, a method using a Maxwell visual optical system (retinal projection, retinal scanning) is known. In Maxwell visual optics, the image to be displayed is focused on the position of the pupil of the user's eye and then diverged and projected onto the retina. That is, it is a method of using the eye like a pinhole camera to form an image on the retina regardless of the accommodation value of the crystalline lens of the eye. For example, Patent Document 1 discloses a retinal scanning display device including two retinal scanning optical systems for the purpose of performing good image processing while suppressing an increase in the amount of image information.

Japanese Unexamined Patent Publication No. 2001-281594

In the method using Maxwell optical system (retinal projection), the image must be focused in the pupil, so the user's field of view (FOV) is narrowed with the limited optical system size such as HMD. There is. In the configuration of Patent Document 1, it is stated that by using two retinal scanning optical systems having different scanning ranges, a user can simultaneously perceive a wide viewing angle image and a high-definition narrow viewing angle image. .. However, there is a problem that the diameter of the eyepiece in front of the eye becomes huge and the display device becomes large. Further, since it is difficult to see an object (landscape) in the real space in front of the user through the display device, it is not suitable for displaying an AR image.

An object of the present invention is to provide a head-mounted display that can be made smaller by ensuring a wide field of view (FOV) while reducing congestion / adjustment (VA) inconsistencies.

In order to solve the above problems, the head mount display of the present invention has a focus-free image display unit that emits a narrow-field focus-free image in the substantially center of the display screen, and a fixed-focus image that emits a wide-field fixed-focus image on the display screen. It includes a focus image display unit and a control unit that controls the display of the focus-free image and the fixed-focus image, and the control unit positions the focus-free image and the fixed-focus image so that they are displayed simultaneously or alternately. The configuration is such that the focus-free image display unit and the fixed-focus image display unit are controlled.

Here, in order to display a focus-free image, a Maxwell visual optical system that focuses the image light at the user's pupil position is adopted, and a polarized beam splitter that reflects the image light emitted from the focus-free image display unit and a polarized beam splitter. The image light retroreflected from the above is provided with a transparent retroreflecting plate having a transparent region in a part thereof, and the image light retroreflected by the transparent retroreflecting plate passes through the polarizing beam splitter and enters the user's eye. It was configured to be.

According to the present invention, it is possible to provide a head-mounted display that can be made smaller by ensuring a wide field of view (FOV) while reducing the disagreement of congestion / adjustment (VA).

The external view of the head-mounted display (HMD) which concerns on Example 1. FIG. The block diagram which shows the internal structure of an HMD. The figure explaining the basic structure of a focus-free image display. The figure which shows the specific structure and operation of the HMD which concerns on Example 1. FIG. The figure explaining image composition. The figure which shows the specific structure and operation of the HMD which concerns on Example 2. FIG. The figure which shows the specific structure and operation of the HMD which concerns on Example 2. FIG. The figure which shows the specific structure and operation of the HMD which concerns on Example 3. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an external view of a head-mounted display (HMD) according to the first embodiment. The HMD 1 has a spectacle-shaped shape, and an image synthesis optical system 9 (a polarization beam splitter 91, a transparent retroreflector 92, etc., which will be described later) that provides an image to the user's eye is arranged on the front surface, and a temple portion (vine) 11 is provided. , Various processing units described later are stored. Further, a part of the processing unit in the temple unit 11 may be separated from the HMD main body and stored in another housing, and may be connected to the HMD main body by a cable or wireless communication.

FIG. 2 is a block diagram showing the internal configuration of HMD1. The HMD 1 includes a main control unit 2, a system bus 3, a storage unit 4, a sensor unit 5, a communication processing unit 6, a focus-free image display unit 7, a fixed focus image display unit 8, an image synthesis optical system 9, and a line-of-sight direction detection unit. It is composed of 10.

The main control unit 2 is a microprocessor unit that controls the entire HMD 1 according to a predetermined operation program. The system bus 3 is a data communication path for transmitting and receiving various commands and data between the main control unit 2 and each constituent block in the HMD 1.

The storage unit 4 stores various programs 41 for controlling the operation of the HMD 1, various data 42 such as operation setting values, detection values from the sensor unit 5 described later, and image contents to be displayed, and is used in the operation of various programs. Has a work area 43 to work on. At that time, the storage unit 4 can store the operation program downloaded from the network, various created data, and the downloaded image content.

The sensor unit 5 is composed of a GPS (Global Positioning System) sensor 51, a geomagnetic sensor 52, a distance sensor 53, an acceleration sensor 54, a gyro sensor 55, etc. in order to detect various states of the HMD1. These sensor groups detect the position, tilt, direction, movement, altitude, etc. of the HMD1.

The communication processing unit 6 is composed of a LAN (Local Area Network) communication unit 61 and a telephone network communication unit 62. The LAN communication unit 61 is connected to a network such as the Internet via an access point or the like, and transmits / receives data to / from each server device on the network. The connection with the access point or the like may be made by a wireless connection such as Wi-Fi (registered trademark). The telephone network communication unit 62 performs telephone communication and data transmission / reception by wireless communication with a base station or the like of a mobile telephone communication network.

Next, as the image display unit, in this embodiment, two image display units are provided, and they are referred to as a focus-free image display unit 7 and a fixed focus image display unit 8. Each image display unit has an

image generation unit

71, 81 that generates an image provided by the user based on an input image signal, and a

display unit

72, 82 that displays the generated image.

The focus-free image display unit 7 has an image generation unit 71 that generates an image having a narrow field of view (FOV) but a deep depth of focus (that is, focus-free). The focus-free image display unit 7 employs, for example, a retinal scanning method using a Maxwell visual optical system described later. On the other hand, the fixed focus image display unit 8 has an image generation unit 81 that has a wide field of view (FOV) and generates an image with a fixed depth of focus. The fixed focus image display unit 8 is a display method used in a conventional general HMD. Each of the

display units

72 and 82 describes a method of converting the light from the light source into a desired image by a spatial light modulator (for example, a liquid crystal panel) (hereinafter referred to as a panel method). A method of displaying an image by scanning with a light source (hereinafter referred to as a laser scanning method) is also possible.

The image synthesizing optical system 9 is an optical system for synthesizing two images generated by the focus-free image display unit 7 and the fixed-focus image display unit 8, and transmits or reflects the incident light according to the polarization direction. It has a polarization beam splitter 91 and a transparent retroreflective plate 92. The transparent retroreflective plate 92 is a reflector (retroreflector) having a characteristic (retroflexivity) of reflecting incident light in the same direction, and has a structure having a transparent region in a part thereof.

The line-of-sight direction detection unit 10 is a so-called eye tracking device that detects the line-of-sight direction (line-of-sight direction and pupil size) of the user wearing the HMD1. The line-of-sight direction can also be obtained by taking an image of the user's face with an internal camera (not shown) provided in the HMD 1 and analyzing the image.

FIG. 3 is a diagram illustrating a basic configuration of a focus-free image display. This is a method of projecting an image onto the retina of the user's eye, and employs Maxwell visual optical system. The focus-free image display unit 7 may be either a panel method or a laser scanning method.

The image light (polarization) emitted from the focus-free image display unit 7 is diverged at a predetermined angle by the variable divergent lens 73, incident on the polarizing beam splitter 91, reflected here, and incident on the transparent retroreflective plate 92. The transparent retroreflector 92 reflects in the same direction as the incident direction (that is, retroreflector), and is re-incidents into the polarizing beam splitter 91. At that time, since the angle of polarization is rotated in the transparent retroreflective plate 92, it is transmitted through the polarization beam splitter 91, focused on the pupil position of the user's eye 20, and projected onto the retina. Since the image is projected on the retina in this way, it is possible to display a focus-free image having a deep depth of focus while having a narrow field of view. In order to ensure that the spot position of the image light is focused on the pupil of the eye, the polarization beam splitter 91 can be adjusted horizontally / vertically, and the variable divergent lens 73 is moved to make the apparent lens 73 in front of the eye. Provide an adjustment mechanism to move the'.

Since the transparent retroreflector 92 retroreflects the image light from the polarizing beam splitter 91 and has a transparent region partially or entirely, the actual object existing in front of the transparent retroreflector 92 is superimposed and visually recognized. (The external light is indicated by the reference numeral L3). In addition, since the transparent retroreflective plate 92 has a planar shape, it is easier to adjust the image light to be focused on the center of the lens of the pupil of the user's eye and projected onto the retina, as compared with the case of the concave reflector. Become.

FIG. 4 is a diagram showing a specific configuration and operation of the HMD 1 according to the first embodiment. The two

image display units

7 and 8 have a hybrid structure in which the

image display units

7 and 8 are arranged at both ends of a shaft passing through the inclined polarization beam splitter 91. In this example, the focus-free image display unit 7 is arranged at the upper end, and the fixed-focus image display unit 8 is arranged at the lower end. The focus-free image display unit 7 has a configuration corresponding to 7 and 73 in FIG.

First, the focus-free image display unit 7 emits the focus-free image light L1. The image light L1 has a polarization direction (for example, H polarization) reflected by the polarization beam splitter 91. The image light L1 is reflected by the polarizing beam splitter 91 and heads toward the front transparent retroreflecting plate 92, and returns as light (V-polarized) whose polarization plane is rotated by the transparent retroreflecting plate 92. It is transmitted, focused on the pupil of the eye 20, and projected onto the retina. This displays a focus-free image with a narrow field of view.

On the other hand, the fixed-focus image light L2 (for example, H-polarized light) emitted upward from the fixed-focus image display unit 8 is reflected by the polarized beam splitter 91 and directly returns to the eye 20. This displays a fixed focus image with a wide field of view.

The light L3 from an external object passes through the transparent retroreflector plate 92, then passes through the polarizing beam splitter 91, and reaches the eye 20. This allows the user to visually recognize the focus-free image and the fixed-focus image overlaid on the external landscape. Here, when the user is using eyeglasses for visual acuity correction, it is possible to use ordinary eyeglasses by arranging them on the outside (opposite side of the eye) of the transparent retroreflector plate 92.

Here, since the focus-free image with a narrow field of view and the fixed-focus image with a wide field of view are generated from a common image, it is necessary to combine and display both images without discomfort. A focus-free image is visible only in a limited central field of view, but because it is an image with a large depth of field, it is possible to avoid a convergence / accommodation (VA) mismatch given to the user. Further, as a visual characteristic of the eye, it is known that the central part of the visual field has a high resolution and the peripheral part has a low resolution. Therefore, it is desirable to display an image with an appropriate resolution according to the area in the field of view.

FIG. 5 is a diagram illustrating image composition of a focus-free image and a fixed-focus image. The image composition algorithm is included in one of the various programs 41 stored in the storage unit 4, and the image composition process is performed by the main control unit 2. The fixed-focus image G2 from the fixed-focus image display unit 8 is displayed in a wide viewing range, whereas the focus-free image G1 from the focus-free image display unit 7 is displayed in a narrow viewing range in a substantially central portion of the fixed-focus image G2. indicate. At that time, the focus-free image G1 is displayed as an image having a higher resolution than the surrounding fixed-focus image G2 because the pixel resolution is improved by using an image taken by a high-definition camera on the screen displayed by the image display unit 7. To.

In image composition, two images G1 and G2 are correctly aligned, and a mask function is used so that the boundary between the two images is smooth and seamlessly transitions. The mask function for the fixed focus image G2 is represented by M2 (broken line), and the mask function for the focus free image G1 is represented by M1 (solid line). The mask function value indicates the passing ratio of the image signal (luminance value), M = 1 is 100% passing, and M = 0 is 0% passing (complete cutoff). At the boundary of the image, the mask function M is changed with a gradient between 1 and 0 so that M1 + M2 = 1 in the transition interval. In this way, the focus-free image G1 is reduced and inserted into the blocked region of the fixed-focus image G2. Further, in the transition section, the unnaturalness is eliminated by shading both images G1 and G2.

In the compositing process of the focus-free image G1 and the fixed-focus image G2, the focus-free image G1 is positioned using the line-of-sight direction parameter detected by the line-of-sight direction detection unit 10, and the optimum mask for the two images G1 and G2. Image composition is performed by setting the functions M1 and M2.

Specifically, it is processed by the following procedure.
(1) First, the direction of the eye (pupil) is determined using the line-of-sight direction parameter.
(2) It is calculated from the viewable range of the focus-free image G1 and whether it is visible from the line-of-sight direction (angle).
(3) Two-dimensional mask functions M1 and M2 representing a change in luminance within a predetermined region are calculated centering on a direction in which the focus-free image G1 is visible.
(4) The calculated mask function M2 is multiplied by the image signal (pixel luminance data) that generates the fixed focus image G2.
(5) The calculated mask function M1 is multiplied by the image signal (pixel luminance data) that generates the focus-free image G1.
(6) In the positioning of the two images G1 and G2, the boundary positions (outer edges) of the images are aligned by rotating and scaling the respective display grids.

In this way, the focus-free image G1 is displayed in a suitable area (direction and size) according to the line-of-sight direction parameter. In addition, by applying the mask function, both images G1. G2 can be displayed as a single seamless image.

The above description is an image composition method when the focus-free image G1 is visible to the user. However, since the field of view is narrowed in the Maxwell visual optical system that focuses the image light at the pupil position, the Maxwell visual optical system may not be established depending on the deviation of the pupil direction depending on the user's line-of-sight direction and the condition of the pupil size. That is, even if the focus-free image G1 is displayed, the user cannot comfortably see it, but rather gives a sense of discomfort. The processing method in that case will be described below.

In order to determine whether the focus-free image G1 is visible, the line-of-sight direction parameters (line-of-sight direction and pupil size) detected by the line-of-sight direction detection unit 10 are used. First, it is determined whether or not the focal spot (front of the eye) of the focus-free image is in the pupil. Next, it is determined whether or not it is visible from the function (vertical angle of the eye, horizontal angle of the eye, pupil size) that maps the 3D coordinates. This function can be determined by displaying a white or colored square only on the focus-free image and confirming that the function table matches the user's visual response.

As a result of the above determination, if the focus-free image G1 is not visible to the user, the focus-free image G1 is not displayed at all (for example, a black image is displayed), and only the fixed-focus image G2 is displayed without masking. In other words, the mask function M2 of the fixed focus image G2 is 1 over the entire screen, and the mask function M1 of the focus free image G1 is 0 over the entire screen.

Further, as a result of the above determination, there are cases where the focus-free image G1 is partially visible to the user, or it is uncertain whether or not it is visible. In this case, the focus-free image G1 is not displayed and only the fixed-focus image G2 is displayed without masking, as in the case where the image is not visible.

As described above, according to the first embodiment, the following effects can be obtained by combining a focus-free image with a deep depth of focus and a fixed-focus image with a wide field of view.
(1) By minimizing the occurrence of congestion / accommodation (VA) discrepancies when viewing virtual reality or augmented reality images, problems of discomfort and eye strain are reduced. This is achieved by arranging the focus-free image in the line-of-sight region (that is, the center of the screen) where the user normally gazes for a long time.
(2) The disadvantage that the field of view (FOV) of a focus-free image with a deep depth of focus is narrow can be overcome by arranging a fixed-focus image with a wide field of view (FOV) around it and displaying both images in combination. To.
(3) At the time of image composition, the pixel resolution is improved by reducing and inserting the focus-free image, and the focus-free image is displayed at a higher resolution than the surrounding fixed-focus image. This matches the visual characteristics of the eye (the central part of the visual field has high resolution), and the user can comfortably view the image.

In the second embodiment, a case where the two

image display units

7 and 8 are configured by a common image display unit will be described.

6A and 6B are diagrams showing a specific configuration and operation of the HMD 1 according to the second embodiment. Here, the single image display unit 12 is commonly used as the focus-free image display unit 7 and the fixed-focus image display unit 8, and the polarization state (H, V) of the image display unit 12 is switched at a predetermined cycle. It realizes the operation as each image display unit. FIG. 6A shows a state of operating as a focus-free image display unit 7 (focus-free image mode), and FIG. 6B shows a state of operating as a fixed-focus image display unit 8 (fixed-focus image mode). Switching between polarization states can be done quickly using a polarized rotator. Further, in this embodiment, as a synthetic optical system, a 1/4 wave plate 93 and a mirror 94 are additionally arranged on the opposite side of the image display unit 12 (lower part of the drawing) via a polarization beam splitter 91.

First, the operation of the focus-free image mode of FIG. 6A will be described. For example, H-polarized image light L1 is emitted from the common image display unit 12, reflected by the polarization beam splitter 91, and directed toward the transparent retroreflector 92. In the transparent retroreflector 92, the retroreflector is reflected and the polarization direction is changed to V-polarization, returns to the polarization beam splitter 91, passes through the polarization beam splitter 91, and is incident on the user's eye 20. In this mode, the Maxwell visual optical system is configured as described in FIG. 3 and a focus-free image is displayed. The image display unit 12 corresponds to the configurations of 7 and 73 in FIG. However, since the image display unit 12 is also a fixed-focus image display unit, the lens as shown in FIG. 3 73 cannot be arranged. Therefore, instead of the lens 73, an element such as a liquid crystal shutter may be used to form a diffraction grating to refract the image light L1.

Next, the operation of the fixed focus image mode of FIG. 6B will be described. For example, V-polarized image light L2 is emitted from the common image display unit 12, passes through the polarization beam splitter 91, is incident on the 1/4 wave plate 93, and is reflected by the mirror 94. Then, by passing through the 1/4 wave plate 93 again, the polarization direction is switched to H polarization (rotation by 90 degrees), and this time, the polarization beam splitter 91 is reflected and incident on the user's eye 20. In this mode, a fixed focus image is displayed.

In Example 2, the focus-free image of FIG. 6A and the fixed-focus image of FIG. 6B are positioned and combined in the same manner as in Example 1. Then, the common image display unit 12 alternately displays the focus-free image and the fixed-focus image by switching the linear polarization (H, V) at a predetermined cycle.

According to the second embodiment, it is possible to realize a head-mounted display that secures a wide field of view (FOV) while reducing the disagreement of the VA as in the first embodiment. Further, according to the second embodiment, since the common image display unit 12 is used, there is an effect that the configuration of the apparatus becomes simpler than that of the first embodiment.

In Example 3, the image lights from the two

image display units

7 and 8 were mixed by a polarizing beam splitter cube and incident on the same synthetic optical system as in Example 2 (FIGS. 6A and 6B). The image display unit 7 has a configuration corresponding to 7 and 73 in FIG.

FIG. 7 is a diagram showing a specific configuration and operation of the HMD 1 according to the third embodiment. The focus-free image display unit 7 and the fixed-focus image display unit 8 are arranged on orthogonal sides of a separately provided polarization beam splitter cube 95, and emit image light whose polarization directions are orthogonal to each other. For example, the focus-free image display unit 7 is arranged on the right side surface of the cube 95 to emit H-polarized image light L1, and the fixed-focus image display unit 8 is arranged on the upper surface of the cube 95 to emit V-polarized image light L2. On the polarization plane of the polarized beam splitter cube 95, the image light L1 (H polarized light) from the focus-free image display unit 7 is reflected and directed downward, and the image light L2 (V polarized light) from the fixed focus image display unit 8 is transmitted. And head down. In this way, the image lights L1 and L2 from the two

image display units

7 and 8 are mixed.

The mixed two image lights (L1 + L2) are incident on the same synthetic optical system as in Example 2. Of these, the focus-free image light L1 is reflected by the polarizing beam splitter 91 and heads toward the transparent retroreflector 92, as shown in FIG. 6A. The transparent retroreflector 92 is retroreflected, returns to the polarizing beam splitter 91, passes through the polarizing beam splitter 91, and is incident on the user's eye 20. On the other hand, as shown in FIG. 6B, the fixed focus image light L2 passes through the polarizing beam splitter 91, enters the quarter wave plate 93, and is reflected by the mirror 94. Then, by passing through the 1/4 wave plate 93 again, the polarization direction is switched to H polarization, and this time, the polarization beam splitter 91 is reflected and incident on the user's eye 20.

Also in the third embodiment, it is possible to realize a head-mounted display that secures a wide field of view (FOV) while reducing the disagreement of the VA as in the first and second embodiments. Compared with the first and second embodiments, according to the third embodiment, the two

image display units

7 and 8 can be arranged on the same side as viewed from the polarization beam splitter 91, and the polarization switching of the image display unit is unnecessary. There is a merit.

Although the embodiments of the present invention have been described above, the configuration for realizing the technique of the present invention is not limited to each of the above-described embodiments, and various modifications can be considered. For example, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. All of these belong to the category of the present invention.

1: Head mount display (HMD), 2: Main control unit, 4: Storage unit, 5: Sensor unit, 6: Communication processing unit, 7: Focus-free image display unit, 8: Fixed focus image display unit, 9: Image Synthetic optical system, 10: Line-of-sight detection unit, 12: Common image display unit, 20: User's eye, 91: Polarization beam splitter, 92: Transparent retroreflector, 93: 1/4 wave plate, 94: Mirror, 95: Polarized beam splitter cube.

Claims

A head-mounted display that is worn on the user's head and displays images of virtual reality or augmented reality.
A focus-free image display unit that emits a focus-free image with a narrow field of view in the center of the display screen,
A fixed-focus image display unit that emits a wide-field fixed-focus image onto the display screen,
A control unit for controlling the display of the focus-free image and the fixed-focus image is provided.
The control unit positions the focus-free image and the fixed-focus image, and controls the focus-free image display unit and the fixed-focus image display unit so that the focus-free image and the fixed-focus image are displayed simultaneously or alternately. Mount display.
The head-mounted display according to claim 1.
In order to display the focus-free image, a retinal scanning optical system that focuses the image light at the position of the user's pupil is adopted.
A polarization beam splitter that reflects the image light emitted from the focus-free image display unit,
It is provided with a transparent retroreflector plate that retroreflects the image light from the polarization beam splitter and has a transparent region partially or entirely.
A head-mounted display characterized in that the image light retroreflected by the transparent retroreflector is transmitted through the polarization beam splitter and incident on the user's eye.
The head-mounted display according to claim 2.
The retinal scanning optical system has a configuration in which the lens position can be adjusted.
A head-mounted display characterized by adjusting the focus on the user's eyes by adjusting the lens position.
The head-mounted display according to claim 2.
The optical system for displaying the fixed focus image is
The fixed focus image display unit is arranged so as to face the opposite side of the focus free image display unit via the polarization beam splitter.
A head-mounted display characterized in that image light emitted from the fixed-focus image display unit is reflected by the polarization beam splitter and incident on the user's eye.
The head-mounted display according to claim 2.
The focus-free image display unit and the fixed-focus image display unit are configured by a common image display unit.
The control unit alternately emits the focus-free image and the fixed-focus image while switching the polarization state of the common image display unit at a predetermined cycle.
As an optical system for displaying the fixed focus image, a 1/4 wave plate and a mirror are arranged on the opposite side of the common image display unit via the polarization beam splitter.
The image light of the fixed focus image passes through the polarization beam splitter, enters the 1/4 wave plate, is reflected by the mirror, passes through the 1/4 wave plate again, and reflects the polarization beam splitter. A head-mounted display that is characterized by being incident on the user's eye.
The head-mounted display according to claim 2.
The focus-free image display unit and the fixed-focus image display unit are arranged on side surfaces orthogonal to each other with the polarization plane of the polarization beam splitter cube in between.
The focus-free image and the fixed-focus image are mixed from the polarization beam splitter cube and emitted toward the polarization beam splitter.
As an optical system for displaying the fixed-focus image, a 1/4 wave plate and a mirror are arranged on the opposite side of the polarization beam splitter cube via the polarization beam splitter.
The image light of the fixed focus image passes through the polarization beam splitter, enters the 1/4 wave plate, is reflected by the mirror, passes through the 1/4 wave plate again, and reflects the polarization beam splitter. A head-mounted display that is characterized by being incident on the user's eye.
The head-mounted display according to claim 1.
When displaying the focus-free image and the fixed-focus image, the control unit applies a mask function to block the fixed-focus image in the substantially center of the display screen, and synthesizes the focus-free image in the blocked region. A head-mounted display characterized by displaying the focus-free image at a higher resolution than the fixed-focus image.
The head-mounted display according to claim 7.
It is equipped with a line-of-sight direction detection unit that detects the line-of-sight direction and pupil size of the user's eyes.
The control unit determines whether the focus-free image can be visually recognized by the user based on the line-of-sight direction and the pupil size detected by the line-of-sight direction detection unit.
As a result of the determination, when the focus-free image is not visible, the head-mounted display is characterized in that the focus-free image is not displayed and only the fixed-focus image is displayed.