KR20190088609A - Foveated Near-Eye Display System for Relieving Vergence-Accommodation Conflict - Google Patents

Abstract

Provided is a foveated near-eye display system for resolving the problem of vergence-accommodation conflict. According to an embodiment of the present invention, a three-dimensional display system comprises: a three-dimensional display for generating a three-dimensional image which is to be provided at a divergence angle for covering a first region; and a two-dimensional display for generating a two-dimensional image which is to be provided at a divergence angle for covering a second region excluding the first region. Therefore, the number of pixels required for the display device can be minimized while the problem of vergence-accommodation conflict is resolved.

Description

{Foveated Near-Eye Display System for Releving Vergence-Accommodation Conflict}

The present invention relates to a three-dimensional display technology, and more particularly, to a foveated near-eye display system for solving a convergent focus mismatch problem.

In the case of commercially available near-eye displays for existing VR / ARs, most of the three-dimensional information is provided using binocular disparity only. Thus, visual fatigue due to convergence focus mismatch is a major obstacle to usability.

Accordingly, a light field (LF) display or a digital holographic (DH) display, which satisfies the hyperchip condition that can solve the convergence focus mismatch and provide accurate focus information, is proposed as an alternative, but an accurate accommodation cue is provided The number of pixels required is much higher than the specification of an existing display.

Alternatively, a near-eye display can be assumed. However, in the case of the near-eye display, there is a problem that the pupil of the user's eye covers a moving area of a wide field of view (FOV) and requires a significantly larger number of pixels than the current 2D display in order to provide accommodation information .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a near-eye display system and method capable of minimizing the number of pixels required for a display device while solving the convergence focus mismatch problem. .

According to an aspect of the present invention, there is provided a 3D display system including a 3D display for generating a 3D image to be provided as a divergent angle for covering a first area; And a 2D display for generating a 2D image to be provided as a divergent angle for covering a second area other than the first area.

The first region may be a foveated region.

The second region may be a peripheral region of the paved region.

The 3D display system according to the present invention may further include a semi-mirror for synthesizing the 3D image generated in the 3D display and the 2D image generated in the 2D display.

A 3D display system according to the present invention includes: a first optical system for transmitting a 3D image generated in a 3D display to a virtual screen; And a second optical system for delivering the 2D image generated in the 2D display to the virtual screen.

The focal lengths of the lenses included in the first optical system may be different from the focal lengths of the lenses included in the second optical system.

The 3D display system according to the present invention may further include a first spatial filter disposed in the first optical system for limiting a divergent angle of the 3D image for covering the first area.

The 3D display system according to the present invention may further include a second spatial filter disposed in the second optical system for limiting a divergent angle of the 2D image for covering the second area.

The 3D display system according to the present invention may further include an alternative lens positioned at the rear end of the virtual screen.

The 3D display system according to the present invention may further include an optical system for transmitting the 3D image generated in the 3D display and the 2D image generated in the 2D display to the virtual screen.

A 3D display system according to the present invention includes a spatial filter disposed in an optical system for limiting a divergence angle of a 3D image for covering a first area and limiting a divergence angle of a 2D image for covering a second area .

The spatial filter may comprise a first polarizer for passing a 3D image of the first polarization state.

The spatial filter may further comprise a second polarizer for passing the 3D image of the second polarization state.

The 3D display may be a light field display or a digital holographic display.

According to another embodiment of the present invention, there is provided a 3D display method comprising: generating a 3D image to be provided as a divergent angle for covering a first area; And generating a 2D image to be provided as a divergent angle for covering a second area other than the first area.

According to another embodiment of the present invention, a 3D display system includes a 3D display for generating a 3D image to provide a divergent angle for covering a first area; And a half mirror for synthesizing the 3D image generated in the 3D display and the 2D image to be provided as the divergence angle for covering the second area other than the first area.

According to another embodiment of the present invention, there is provided a 3D display method comprising: generating a 3D image to be provided as a divergent angle for covering a first area; And synthesizing a 2D image to be provided as a divergent angle for covering the generated 3D image and a second area other than the first area.

According to another embodiment of the present invention, a 3D display system includes a 2D display for generating a 2D image to be provided as a divergent angle for covering a second area other than the first area; And a half mirror for combining the 3D image to be provided with the divergence angle for covering the first area and the 2D image generated in the 2D display.

As described above, according to the embodiments of the present invention, the number of pixels required for the display device can be minimized while solving the convergence focus mismatch problem.

FIG. 1 shows the emission characteristics of each pixel of an LF or DH display,
Figure 2 illustrates a basic concept for implementing a paved LF or DH display,
FIG. 3 is a graph illustrating the light-diverging characteristics of the Foveated LF or DH display,
4 shows the observation characteristics of the Foveated LF display,
5 shows the observation characteristics of the Foveated DH display,
FIG. 6 illustrates an optical setup for implementing a Foveated LF or DH display according to an embodiment of the present invention,
FIGS. 7 and 8 illustrate a mutually exclusive spatial filter,
9 and 10 illustrate the angular range of an LF or DH display on an intermediate virtual screen,
11 shows the emission characteristics of each pixel on the intermediate virtual screen,
Figure 12 shows the optical configuration of a foveated LF or DH display system with one optical path,
FIG. 13 illustrates a Polarization-base mutually exclusive spatial filter,
14 illustrates parameterization for determining the divergence angle of each pixel of the LF or DH display,
15 is a parameterization for determining the divergence angle of each pixel of the LF or DH display.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the optical characteristics of a light field (LF) display or a digital holographic (DH) display based on a hyperchip, which can transmit accurate accommodation information to a user.

In the case of the LF display, the resolution of the display must be sacrificed in proportion to the light emitted from the pixels in order to give different information to each direction, and there is a limit to the resolution, so that the light field When the angle sampling rate is increased, the angular range in which each pixel provides meaningful information becomes very narrow.

Also, in the case of the DH display, a significant diffraction angle range is determined in inverse proportion to the sampling interval of the display pixel, and in a typical display, this diffraction angle becomes very narrow. As a result, the angular range that can provide meaningful information at each pixel of the LF or DH display is limited as shown in FIG. 1, and the angle is usually determined to be a very small value.

Thus, in the case of LF and DH displays, as in the space-bandwidth product of the DH display, the field of view (FOV) is very limited and the position of the observer is extremely limited when implemented with the number of pixels of the existing display system.

Accordingly, the number of pixels required to function as an LF or DH display system that provides precise accommodation information on the range of the pupil of the user's eye that has a wide FOV as in a general Near-Eye display system is significantly increased.

In particular, if an eye piece lens is mounted in front of an LF or DH display and all of the chief rays emitted from each pixel are condensed to enter the pupil, it can be implemented as an LF or DH display for the entire FOV. However, The size of the field of view that can be designed in numbers is similar to the pupil, so there is little room for the observer's eye to move.

On the other hand, when the display screen, the eye piece lens, and the positional relation of the user's eye are determined so that the chief rays of each pixel of the display screen imaged by the eye piece lens are focused at the center of the eye pupil rotation, Can be implemented to function as an LF or DH display with respect to the direction in which the user's pupil is located on the trajectory and a part of the periphery thereof if the divergence angle of the pupil is not large enough to cover the entire eye pupil trajectory.

Since the lens focal length of the eye is usually determined by a part of the entire FOV near the viewing direction, the minimum area where convergence focus mismatch does not occur is defined as a foveated region when an accurate accommodation cue is provided. If accommodation cue is provided only for the above area, it can be expected that convergence focus mismatch problem will not occur.

Therefore, if the divergence angle of the light emitted from each pixel on the image of the screen functioning as an LF or DH display after the system as shown in Fig. 2 is more than enough to cover the foveated region in view of the viewer's pupil Even if the divergence angle does not cover the entire eye pupil trajectory, it may be possible to solve convergent focus mismatch problem.

However, in this case, no image information is provided for regions other than the foveated region.

In the embodiment of the present invention, image information as a 2D display is provided for divergent angles other than the foveated region. In other words, as shown in FIG. 3, in the embodiment of the present invention, when the virtual screen is assumed to be the image of screen in FIG. 2, the divergence angle around the chief ray, which covers the foveated region, , A display system that functions as an LF or DH display capable of providing accommodation information and functions as a 2D display for other divergence angles.

When the user observes the foveated LF or DH display system according to the embodiment of the present invention, as shown in FIGS. 4 and 5, the pixel in the direction of interest is recognized as a 3D pixel providing accommodation information, A pixel at a viewing angle beyond the region is recognized as a 2D pixel without accommodation information. If the foveated region is properly set, the entire FOV does not provide accommodaton information, but the convergence focus mismatch problem does not occur.

FIG. 6 shows a specific optical setup for implementing a foveated LF or DH display system according to an embodiment of the present invention.

A foveated display system according to an embodiment of the present invention includes an LF or DH display 110 and a 2D display 140. The LF or DH display 110 passes through a 4f system 120 consisting of lenses with focal lengths f ₁ and f ₂ and the 2D display 140 is made up of lenses with focal lengths f ₃ and f ₄ 4f system 150 and onto a half mirror (Half Mirror) 170 over a plane named as the intermediate virtual screen 175.

At this time, mutually exclusive spatial filters 130 and 160 shown in FIGS. 7 and 8 are arranged in the frequency domain of each 4f system. Spatial filters 130 and 160 determine the angle of light emitted from each pixel in the intermediate virtual screen 175.

The spatial filter 130 located in the 4f system 120 of the LF or DH display 110 limits the 3D image to be provided by the divergence angle for covering the paved area as shown in Fig.

The spatial filter 160 located in the 4f system 150 of the 2D display 140 is configured to limit the 2D image to a divergent angle for covering the peripheral area of the paved area, do.

9 and 10, the relationship between the coordinates of the spatial filter 130 and the angles is determined by the following equation when the LF of the intermediate virtual screen 175 or the light emission angle of each pixel of the DH display 110 is parameterized as shown in FIGS.

Also, since the focal lengths of the 4f system 120 for the LF or DH display 110 and the lenses used for the 4f system 140 for the 2D display 130 are different, the 2D display system 130) is scaled with a coordinate value of f ₄ / f ₂ .

Through such a system configuration, the intermediate virtual screen 175 functions as an LF or DH display at an angle within θ _{D of} light emitted from each pixel as shown in FIG. 11, and functions as a 2D display at other angles . In this case, the chief rays from each pixel are all parallel. As shown in FIG. 6, by placing an eyepiece lens 180 having a focal distance F at a distance g from the rear end of the intermediate virtual screen 175, And the luminescence characteristics of each pixel of the virtual screen are as shown in Fig. 3 as intended.

If the 4f system 120 for the LF or DH display 110 and the 4f system 150 for the 2D display 140 use lenses of the same focal length, Can be combined into a sight path.

At this time, the polarization-based mutually exclusive spatial filter 220 operates as a spatial filter for the LF or DH display 110 and the 2D display 140 based on the polarization state. Accordingly, the LF or DH display 110 and the 2D display 140 must have orthogonal polarization states, which can be achieved by imparting a polarization state to the light source or attaching a polarizer to the front of the display.

The LF or DH display 110 and the 2D display 140 are combined into a single optical path through the half mirror 170. Since each display has orthogonal polarization states, the polarization beam splitter (PBS) Giving it may be advantageous in light efficiency. Thereafter, the two displays pass through a 4f system 210 comprising lenses having f ₁ and f ₂ focal lengths, and the polarization-based mutually exclusive spatial filter 220 as shown in FIG. 13 is located in the frequency domain.

At this time. If an aperture is made in a polarizing plate having a polarization state orthogonal to the LF or DH display 110 and the aperture is blocked by a polarizing plate having a polarization state orthogonal to the 2D display 140, The optical information passes only through the aperture portion and the optical information from the 2D display 140 is blocked only by the aperture portion so that it functions as a mutually exclusive spatial filter 130,160 for each display as shown in Figures 7 and 8 Can be implemented simultaneously.

14 is a basic parameterization for determining the divergence angle of optical information in each pixel of an LF or DH display used to implement a foveated LF or DH display according to an embodiment of the present invention.

The virtual screen is z _D away from the forefront of the user's eye, and the radius of rotation of the user's pupil is r. In this case, since the center of rotation of the user's pupil is distant from the eyepiece lens by the focal distance F, all of the chief rays emitted from each pixel of the virtual screen are collected at the center of the user's pupil rotation.

When the total FOV of the virtual screen is determined by θ _FOV , the foveated region is characterized by θ _fv , which is part of it. When the user observes the center of the virtual screen, the magnitude of the optical information scattering angle per pixel of the LF or DH display on the virtual screen is determined by the boarder pixel of the foveated region, The angle of view is? _B. At this time, θ _B is determined by the following equation.

As shown in FIG. 15, when the user is watching the center of the virtual screen, the center of the pupil having the width of P _E is denoted by P _o , and the divergence angle of the LF or DH display per pixel is denoted by θ _D , And the point at which the outermost ray meets the pupil is called P _D. At this time, LF, or because the optical information of each pixel in the dispersion of the DH display is to be covered to some extent than the area of the pupil may differ depending on the situation which causes the accommodation response, placing the value to δ _A, the pupil more δ _A It is possible to calculate the per-pixel divergence angle &thetas; _D that can cover the area. This condition is determined by the following inequality.

When the above obtained θ _B is rearranged, θ _D is determined so as to satisfy the following inequality.

Up to now, a preferred embodiment has been described in detail for a paved near-eye display system for solving convergent focus disparity problems.

Specifically, in the embodiment of the present invention, accommodation information is provided only for a foveated region, which is a part of the entire FOV, using the concept of foveation, thereby minimizing the number of display request pixels for resolving the convergence focus mismatch. We implemented a near eye display in which the convergence focus problem was solved without increasing the number of pixels significantly. Thereby, the number of pixels required for the display device can be minimized while solving the convergence focus mismatch problem.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

110: LF or DH display
120, 150, 210: 4f system
130, 160, 220: spatial filter
140: 2D display
170: Half Mirror
175: intermediate virtual screen
180: eyepiece lens

Claims (18)

A 3D display for generating a 3D image to provide as a divergent angle for covering the first area; And
And a 2D display for generating a 2D image to be provided as a divergent angle for covering a second area other than the first area.
The method according to claim 1,
In the first region,
Wherein the 3D display system is a Foveated Region.
The method of claim 2,
In the second region,
Is a peripheral region of the paved region.
The method of claim 2,
And a semi-mirror for synthesizing the 3D image generated in the 3D display and the 2D image generated in the 2D display.
The method of claim 4,
A first optical system for delivering the 3D image generated in the 3D display to the virtual screen; And
And a second optical system for delivering the 2D image generated in the 2D display to the virtual screen.
The method of claim 5,
The focal lengths of the lenses included in the first optical system,
Wherein the second optical system is different from the focal lengths of the lenses included in the second optical system.
The method of claim 5,
And a first spatial filter disposed in the first optical system for limiting a divergent angle of the 3D image for covering the first area.
The method of claim 7,
And a second spatial filter disposed in the second optical system for limiting a divergent angle of the 2D image for covering the second region.
The method of claim 8,
And an alternative lens positioned at a rear end of the virtual screen.
The method of claim 4,
And an optical system for transmitting the 3D image generated in the 3D display and the 2D image generated in the 2D display to the virtual screen.
The method of claim 10,
Further comprising a spatial filter disposed in the optical system for limiting divergence angles of the 3D image for covering the first area and limiting divergence angles of the 2D image for covering the second area, system.
The method of claim 11,
The spatial filter,
And a first polarizer for passing the 3D image of the first polarization state.
The method of claim 12,
The spatial filter,
And a second polarizer for passing the 3D image of the second polarization state.
The method according to claim 1,
The 3D display,
A light field display or a digital holographic display.
Generating a 3D image to provide as a divergent angle to cover the first area; And
And generating a 2D image to be provided as a divergent angle for covering a second area other than the first area.
A 3D display for generating a 3D image to provide as a divergent angle for covering the first area; And
And a half mirror for synthesizing a 3D image generated in the 3D display and a 2D image to be provided as a divergence angle for covering a second area other than the first area.
Generating a 3D image to provide as a divergent angle to cover the first area; And
And combining the generated 3D image with a 2D image to be provided as a divergence angle to cover a second area other than the first area.
A 2D display for generating a 2D image to be provided as a divergent angle for covering a second area other than the first area; And
And a semi-mirror for synthesizing a 3D image to be provided as a divergence angle for covering the first area and a 2D image generated in the 2D display.

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