JP2011145607A - Head mount display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the problem of contradiction between convergence angle and focal distance of eyes causing a problem of a head mount display for performing three-dimensional moving image display, and to reduce the necessity for combined use of the head-mounted display and glasses and necessity for focal distance adjustment. <P>SOLUTION: In a head mount display, a shutter mechanism 3R has a plurality of optical local openings 3A between a display element 2 and a pupil assumption region having positions and size of the pupils of both eyes assumed during wearing. The positions of the local openings 3A are switched with time at a high speed. A synchronous display control section 5 changes the display position of a partial image 2A on the display surface of display element 2 synchronously with the position of the local opening 3A of the shutter mechanism 3R. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a head-mounted display that has a display element and is mounted on a head or ear so that the display element comes in front of the eyes.

  In a general head mounted display (HMD), the display element is viewed through a static optical system such as a lens or a reflecting mirror. In this configuration, the image by the display element appears to exist at an apparent fixed distance point (virtual image position) determined by the optical system.

A pinhole camera is known.
With a camera using a normal lens, a blurred image is taken of an object that is shifted back and forth from the focused object. On the other hand, it is known that a camera using a pinhole can capture a focused image regardless of the distance between the object and the distance between the pinhole and the film. This property is called pan focus.

An idea is known in which a large number of pinholes are regularly arranged in front of a display element to limit the emission direction of light emitted from the display element and provide an appropriate stereoscopic image according to the position of the eye ( For example, see Patent Document 1).
In addition, there is a proposal to change the pinhole position by using a liquid crystal element or the like, but the purpose is to perform 3D display corresponding to a plurality or changing positions of the viewer's eyes.

Japanese Patent No. 3523605

In the HMD that performs 3D display, if the distance perceived from the shift of the left and right images and the display position on the fixed distance are shifted, there is a concern that discomfort or disagreement of the focal distance may occur, causing problems such as eye strain or headache. Is done.
In addition, when a person who regularly uses glasses wears the glasses when using the HMD and is able to wear the HMD from the top, it is necessary to increase the HMD size. If you remove the glasses and wear the HMD, you will see a blurred image.
To deal with the above-mentioned problem caused by being out of focus, it is easily conceivable to deal with pan-focus using a pinhole, but in this case, the image becomes extremely dark and the field of view is narrowed.

  As shown in Patent Document 1, assuming a display device larger than the HMD and using a plurality of pinholes, the distance between the pupil and the pinhole is long, so it is easy to make the pinhole interval and the pixel pitch comparable. The entire image can be displayed at a reasonable resolution.

However, when the technique described in Patent Document 1 is applied to the HMD as it is, the distance between the eyes is close to the pinhole or shutter mechanism, so if the pinhole interval is made too small, light emitted from one point on the display element is emitted. It reaches the eyes via multiple pinholes and the pan focus effect is lost.
However, when the pinhole interval is made larger than the pixel interval of the display element, the image display is finely divided as if viewed through a mesh.

  The present invention newly provides a head-mounted display that does not have the above-described problems or is reduced.

The head mounted display according to the present invention includes a display element, a shutter mechanism, and a display control unit.
The shutter mechanism controls the formation of a plurality of optical local openings. The shutter mechanism interposes a plurality of optical local openings between an assumed pupil region having the position and size of pupils of both eyes assumed at the time of wearing and the display element. Then, the position of the local opening is switched at a high speed with time.
The display control unit switches the display position of a partial image on the display surface of the display element at high speed in synchronization with the position of the local opening of the shutter mechanism.

According to the above configuration, even if the distance between the local openings is increased so that the linear image light passing through the two or more local openings does not reach the pupil, the local openings are separated by the high-speed switching operation of the local positions. Therefore, there is no unevenness such as intensity of image light. In addition, partial image display that should pass through the local opening is performed in synchronization with the local opening. This partial image with a narrow display range reaches the assumed pupil region that defines the pupil position only when it passes through one corresponding local opening. Even if it passes through another local opening, since there is no pupil beyond that, it does not affect the visual recognition of the image.
When a display image is scanned and displayed with such local image light, each image light that reaches the pupil for a short period of time is linear, and a visually recognized image appears as a collection of such many linear image lights. , The image is not out of focus.

  According to the present invention, it is possible to reduce a problem caused by a contradiction between a convergence angle and a focal length in an HMD that performs 3D display, and to newly provide a head-mounted display that requires less spectacles and focal length adjustment. Can do.

It is a schematic block diagram (top view) of HMD in connection with 1st Embodiment. It is a schematic diagram for illustrating the opening control method of the local opening of the shutter mechanism. It is explanatory drawing which shows the optical path which passes through several local opening provided in the shutter mechanism. It is explanatory drawing of the visual field size of 1 pinhole in the multipinhole display system using the large sized display of a 2nd comparative example. It is explanatory drawing of the visual field size which passed through one pinhole in HMD of a 3rd comparative example. It is a schematic diagram which shows the opening shape of the local opening of the shutter mechanism in 2nd Embodiment. It is a schematic block diagram (top view) of HMD in connection with 3rd Embodiment.

Embodiments of the present invention will be described in the following order with reference to the drawings.
Hereinafter, description will be given in the following order.
1. First embodiment: an embodiment in which a single display element and a shutter mechanism are arranged in parallel.
2. Second Embodiment: An embodiment in which the aperture area of the shutter mechanism is increased toward the outside, and the aperture visual field area from the pupil position is made uniform.
3. Third Embodiment: An embodiment in which both the single display element and the shutter mechanism have a curved surface.

<1. First Embodiment>
[Device configuration]
FIG. 1 is a schematic configuration diagram viewed from above when a head mounted display (HMD) according to the first embodiment is mounted on a human head so that a display element comes in front of eyes.
The HMD 1 illustrated in FIG. 1 is configured by mounting each part shown in a goggle or glasses-like mounting frame member (not shown). A mounting frame member (not shown) can be positioned by fitting the face shape, ears, nose, and the like. In order to prevent the dropout, the mounting frame member structure is such that the portion fixed to the head, or the temple is pressed inward, or is engaged with the ear or the like.

A display element indicated by reference numeral “2” is fixed near the front end surface of the mounting frame member (not shown).
Since the size and weight of the display element 2 greatly affect the design and wearing feeling of the HMD, it is desirable that the display element 2 be light and high definition such as liquid crystal or organic EL.

  Assume an assumed pupil area having a size corresponding to the size of the pupil at the position where the left and right pupils are expected to come. Between the assumed pupil region and the display element 2, a shutter mechanism 3 as an optical component and two eyepieces 4R and 4L are disposed from the display element 2 side.

The shutter mechanism 3 desirably performs shuttering using light modulation of liquid crystal or the like (however, in this case, only light transmission and light blocking functions). As described later, since it is necessary to control display and synchronization at high speed, it is advantageous that the mechanism is similar to the display element 2.
Although details will be described later, the shutter mechanism 3 has a function of opening a plurality of local apertures that are considerably smaller than the diameter of the pupil as transmission windows for the linear image light. Moreover, it is necessary to switch positions at high speed. Therefore, although a physical (mechanical) shutter is possible in principle, it is desirable in terms of high-speed switching to change the optical properties of the material and the like without changing the mechanism.

The eyepieces 4R and 4L are used to show an image on the display element at an appropriate virtual image position, like the HMD to which the present invention is not applied. Since the effect of pan-focusing by a pinhole is finite, the eyepieces 4R and 4L are used in combination with the pinhole in order to make focusing easier.
The lens material is not limited, but plastic is desirable for weight reduction. Further, a lens relative position adjusting mechanism may be provided in accordance with the binocular distance.

In the case of an optical shutter in which the shutter mechanism 3 is electrically controlled, for example, a liquid crystal shutter, it is necessary to electrically control the local opening. In addition, it is necessary to display a partial image synchronized with the position and size corresponding to the local opening on the display element 2 and to switch them.
In this example, it is desirable that the HMD 1 includes the synchronous display control unit 5 as a circuit for this shutter control and display data generation control when displaying a partial image on the display element 2. Requirements for synchronous control will be described later.

The synchronous display control unit 5 may be a small circuit embedded in a frame or the like if the HMD 1 is a glasses type, or may be a circuit mounted in a box attached to the viewer's head or the like if the size is slightly large. . Usually, a power source for driving the display element (and the shutter mechanism 3 in the case of electrical control) is required. The synchronous display control unit 5 may be arranged in the vicinity of the power source, or may be embedded in the outer frame portion of the HMD 1 together with the power source (for example, a battery).
The synchronous display control unit 5 can be provided not in the HMD 1 but in an external device. The synchronous display control unit 5 may be provided in another device on the image supply side, such as a personal computer (PC), an AV stationary device, or a mobile device. In this case, the HMD 1 may be configured to receive the converted data from the external device via a wired, wireless, or media such as a memory card.

  The synchronous display control unit 5 includes an input unit for image data such as a wired input terminal, a wireless antenna, or a memory card interface.

The image generated and controlled by the synchronous display control unit 5 may be either a 2D image or a 3D image.
Note that the synchronous control of the local opening by the shutter mechanism 3 and the partial image by the display element 2 performs image display as a set of linear image light passing through the local opening. An image composed of such linear image light is hardly out of focus. Therefore, if the pitch of the local openings can be made sufficiently small within the range where there is no interference with the linear image light, the eyepieces 4R and 4L may be unnecessary.

[Example of local opening of shutter mechanism]
FIG. 2 is a schematic diagram for illustrating an opening control method of a local opening of the shutter mechanism.
FIG. 2 shows a part of the shutter mechanism. One grid represents one opening control unit. For example, nine aperture control units are grouped into one group, and the local aperture is moved in a time division manner in the order of the numbers in the grid. FIG. 2 shows the moment when the local opening in the fifth opening control unit is opened. When the size of the opening control unit of the shutter mechanism is smaller than one opening control size (local opening size), the position changing pitch of the local opening may be made smaller than the size of the opening control unit. In this case, for example, a local opening may be opened between the numbers 5 and 6.

[Example of relationship between multiple openings of shutter mechanism and display pixels]
FIG. 3 shows an optical path passing through a plurality of local openings 3A provided in the shutter mechanism 3 when the eye and the display element 2 are viewed from above.
White radial figures indicate light rays that reach the pupil via the partial display of the display element 2 and the local aperture of the shutter mechanism. Light is emitted from the display element 2 in a direction other than the illustrated light beam, and some of the light leaks out through the local opening, but does not enter the visual region because it is out of the direction of the pupil. . For example, in FIG. 3, the light beam L2 indicated by the oblique lines does not enter the pupil because it passes through the local opening 3A different from the light beam L1 that exits from the same display position (partial image 2A) and reaches the pupil. In this way, control is performed so that only one ray from one display position (partial image 2A) reaches the pupil and other rays including the ray L2 do not reach the pupil at a certain time. It is desirable to do so that the images do not interfere.
In order to satisfy this, the interval between the pixel display and the shutter local aperture is appropriately selected so that unnecessary rays do not enter the pupil.

However, the actual pupil position varies depending on the person and when the mounting position of the wearing tool is not sufficient. Therefore, the pixel display and the shutter local aperture are assumed on the assumption of a pupil assumed region (virtual pupil region) having a size and position so that there is no interference between image lights (simultaneous arrival at the pupil) even if there is some variation. It is desirable to define the interval of. This virtual pupil region is larger than the actual size of the pupil (the diameter changes from 2 [mm] to a maximum of 6 [mm]), and accordingly, a margin is given in consideration of the mounting accuracy of the wearing tool.
For example, the assumed pupil area is a virtual circular area having a diameter obtained by adding a positional deviation margin width at the time of wearing to 6 [mm] which is the maximum diameter of the pupil.

[Preferred requirements for synchronous display control]
The above desirable requirements are precisely as follows.
(1) As a premise, the plurality of local openings 3A need to be regularly arranged in a plane with a mutual distance.
(2) As a requirement in this case, the minimum distance between the local openings 3A is two or more local areas at the same time in a pupil assumed area (a virtual pupil area having a size corresponding to the eyes of both eyes whose position is assumed at the time of wearing). The linear image light from the aperture is defined as a value that is not incident.

  The HMD 1 may have a pupil alignment function. For example, when the HMD 1 is mounted, one light beam may be emitted from the front of the pupil through the local opening in front of the pupil, and the HMD 1 may be mounted at a position where it can be seen well.

In the above configuration, if the display by the synchronous display control unit 5 and the speed at which the opening is moved in synchronization are too slow, it is not possible to suppress the mesh-like display unevenness that becomes a problem in the static case where the movement control is not performed. The requirements for preventing this are as follows.
(3) The shutter mechanism 3 and the synchronous display control unit 5 are visually recognized images in the assumed pupil region, and the fact that the local openings 3A are regularly arranged at least the above-mentioned minimum distance is image division and light intensity. An afterimage effect that is so high that the image becomes uneven and cannot be seen is obtained. For this purpose, the local aperture 3A and the position of the partial image are synchronously controlled at high speed.

Also, if there is a positional synchronization shift, the image itself does not look beautiful. The requirements for no synchronization loss are as follows.
(4) When synchronously controlling the partial image and the local aperture, the pupil is ahead of the direction passing through the center of the local aperture 3A from the center of the partial image 2A (for example, the central axis direction of the light beam L1 shown in FIG. 3). An assumed area must exist. In order to satisfy this need, the display element 2 and the synchronous display control unit 5 control the relative positions of the partial image 2A to be synchronously controlled and the local opening 3A.

[Effect in comparison with comparative example]
Next, comparative examples relating to HMD and pinhole image display will be described, and the effects of the present embodiment will be described in comparison with them.

<< First Comparative Example >>
FIG. 4 is an explanatory diagram of the visual field size of one pinhole in the multi-pinhole display system using a large display.
This large display assumes 0.5 [m] from the front panel 30 to which the multi-pinholes are regularly opened to the display element 20 and 2 [m] from the front panel 30 to the visual recognition position (pupil position).
In this example, the pixel range (diameter) that can be seen through one pinhole is obtained by adding the pinhole diameter to about 6 × 0.5 / 2≈1.5 [mm]. Therefore, the interval between the multi-pinholes can be 2 to 3 [mm], and if a large display element having a lateral width of 1 to 2 [m] is used, display can be performed with a resolution of 500 to 1000 pixels in the horizontal direction.

<< Second Comparative Example >>
FIG. 5 is an explanatory diagram of the visual field size through one pinhole in the HMD. In the first comparative example, both distances of 0.5 [m] and 2 [m] are assumed to be 4 [cm].
The second comparative example corresponds to a case where the synchronous switching control of the local opening (corresponding to a pinhole) is not performed in the HMD 1 of the first embodiment.

In this example, the pixel range (diameter) seen through one pinhole is about 6 [mm]. In the case of a multi-pinhole, the pinhole interval needs to be about 3 [mm] or more.
On the other hand, when the horizontal width of the display element 20 is 20 [cm] and the number of pixels is 1000, the width of one pixel is 0.2 [mm]. Therefore, when the pinhole pitch is larger than the display pixel pitch and the pinhole position is fixed, a mesh-like display is obtained.

In contrast to the comparative example described above, the present embodiment provides the following effects.
It can be brought close to pan focus (in English, deep focus) using the same principle as a pinhole camera. Therefore, the contradiction between the convergence and the focal length in 3D display by the head mounted display can be reduced, and medical problems such as eye strain when used for a long time can be reduced.
Even people who need eyesight correction with glasses can see images with little blur without glasses.

  Since a plurality of local apertures (corresponding to pinholes) are used, the display image is brighter and the field of view is wider than that of the 1-pinhole method.

  In the case of the third comparative example in which a plurality of pinholes are fixed positions, in order to obtain a pan focus effect, it is necessary that light rays from one display pixel enter the pupil via only one pinhole. For this purpose, it is necessary to separate the pinhole intervals to some extent in consideration of the maximum pupil diameter. In that case, an image via a plurality of pinholes can be displayed as only a part of the image of the display element, and looks as if looking through the mesh.

  In this proposal, since the light emitting area (partial image) of the display element 2 corresponding to the position of the local opening 3A (corresponding to a pinhole) is switched at high speed, the joint of the image is not conspicuous for each of the plurality of local openings due to the afterimage effect. All images on the display element 2 can be seen.

<2. Second Embodiment>
FIG. 6 is a schematic diagram illustrating an opening shape of a local opening of the shutter mechanism according to the second embodiment.
Each rectangular area shown in FIG. 6 represents an opening control unit in the same manner as the grid in FIG. There is one or a fixed number of local openings in one opening control unit. That is, the rectangular area shown in FIG. 6 represents the density of local openings. Specifically, since the area of the rectangular region is smaller toward the center of the screen, the density (= number / area) is higher, and the density is lower toward the outside.

The reason why the arrangement pitch of the local openings is made sparse toward the outside in this way is to make the image viewed from the eyeball or the viewing angle of the local openings constant regardless of the surface position. In other words, since the light ray enters the pupil straight at the center of the image, it becomes an aperture control unit having a substantially illustrated area. On the other hand, since the outer side is viewed from an oblique direction, the visual field area (area seen from the pupil) of the aperture control unit is narrower than the illustrated size. As a result, the visual field area is made uniform in the screen.
Since the same number of local apertures are provided in any aperture control unit, the increase / decrease in the visual field area of the aperture control unit is directly the increase / decrease in the visual field area of the local aperture.

In the second embodiment, there is a difference between FIG. 6 and FIG. 2, but the other configurations are the same as those of the first embodiment.
Therefore, the effects described in the first embodiment can also be obtained in this embodiment.
In addition, the second embodiment has an effect that the number of pixels of the display element and the number of control units of the shutter mechanism can be reduced by sufficiently suppressing the resolution of the unnecessary screen edge.

<3. Third Embodiment>
FIG. 7 is a diagram corresponding to FIG. 1 according to the third embodiment.
7 is different from FIG. 1 in that the display element 2B has a curved surface in which the display surface is bent in a direction in which the distance from both eyes is made uniform in a horizontal stroke.
The second difference is that the eyepieces 4R and 4L are aspherical surfaces in which the focal length is different between the central portion and the peripheral portion of the lens, or the focal length is continuously changed corresponding to the curvature of the display surface. Having a structure.
A third difference is that the shutter mechanism 3B is bent in a direction that makes the distance from the eyeball uniform according to the lens surface. Here, the direction to be uniformed is not necessarily bent until it is uniformed, but it is sufficient that the direction is evenly bent as much as in FIG. Such a shutter mechanism 3B is preferably a light transmission type liquid crystal shutter or the like.
In other configurations, FIG. 7 is common to FIG.

  According to the present embodiment, in addition to the same effects as those of the first embodiment, an effect that a large viewing angle can be handled with a small area can be obtained. Further, since the line of sight is inclined at the end of the shutter arranged on the plane, the light transmittance of the liquid crystal shutter and the filter differs from the central portion. In this embodiment, the deviation of the light transmittance can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... HMD, 2, 2B ... Display element, 2A ... Partial image 3, 3B ... Shutter mechanism, 3A ... Local aperture, 4R, 4L ... Eyepiece, 5 ... Synchronous display control part

Claims (9)

A display element;
A shutter that interposes a plurality of optical local openings between the display element and a pupil assumed area having the position and size of the eyes of both eyes assumed at the time of wearing, and switches the position of the local openings with time. Mechanism,
A display control unit that switches a partial image display position on the display surface of the display element at high speed in synchronization with the position of the local opening of the shutter mechanism;
A head mounted display. The plurality of local openings are regularly arranged in a plane at a distance from each other,
The head-mounted display according to claim 1, wherein a minimum distance between local openings is defined as a value at which linear image light from two or more local openings is not simultaneously incident on the assumed pupil region. The shutter mechanism and the display control unit are visually recognized images in the assumed pupil region, and image irregularities in which local openings are regularly arranged at a distance of the minimum distance or more are image division and light intensity. The head mounted display according to claim 2, wherein the position of the local opening and the partial image is synchronously controlled at high speed so as to obtain an afterimage effect that is so high that it cannot be seen. When the display element and the display control unit synchronously control the partial image and the local aperture, the assumed pupil region exists in the direction from the center of the partial image to the center of the local aperture. The head mounted display according to claim 3, wherein the relative position between the partial image to be synchronously controlled and the local opening is controlled. The head-mounted display according to claim 4, wherein the assumed pupil area is a virtual circular area having a diameter obtained by adding a positional deviation margin width at the time of wearing to 6 [mm] which is the maximum diameter of the pupil. The pixel pitch of the display element, the pitch of the control unit of the local opening of the shutter mechanism, or both pitches are different between the central part and the peripheral part, and the peripheral part pitch is larger than the central part. 4. Head mounted display according to The pixel pitch of the display element, the pitch of the control unit of the local opening of the shutter mechanism, or both pitches are different between the central part and the peripheral part, and the peripheral part pitch is larger than the central part. The head mounted display according to 1 The display surface of the display element, the surface for controlling the position of the local opening of the shutter mechanism, or both surfaces are more uniform than the planar configuration in which the distance from the pupil to the display element or the shutter mechanism is parallel. The head mounted display according to claim 4 which is a curved surface. The display surface of the display element, the surface for controlling the position of the local opening of the shutter mechanism, or both surfaces are more uniform than the planar configuration in which the distance from the pupil to the display element or the shutter mechanism is parallel. The head mounted display according to claim 1 which is a curved surface.

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