WO2024188002A1

WO2024188002A1 - Light field display apparatus

Info

Publication number: WO2024188002A1
Application number: PCT/CN2024/076317
Authority: WO
Inventors: 刘玉杰; 梁蓬霞; 程芳
Original assignee: 京东方科技集团股份有限公司
Priority date: 2023-03-13
Filing date: 2024-02-06
Publication date: 2024-09-19
Also published as: CN116300132A

Abstract

A light field display apparatus, comprising: a display panel, provided with a plurality of sub-pixels arranged in an array and used for emitting a plurality of light rays having different pieces of image information; a first optical element, located on the light emitting side of the display panel and used for enabling the plurality of light rays emitted by the display panel to form a plurality of virtual viewpoints which can be focused with one eye; and a second optical element (9), provided on the side of the first optical element away from the display panel and used for modulating light rays emitted from the first optical element to form a plurality of viewpoints entering the human eye (30), so as to improve the resolution of the viewpoints.

Description

Light field display device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202310264973.5 filed in China on March 13, 2023, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to the technical field of display product manufacturing, and in particular to a light field display device.

Background Art

In current near-eye displays, 3D objects are displayed to the user's left and right eyes to form a stereoscopic vision. However, 3D displays based on human stereoscopic vision will lead to convergence conflicts, which will cause visual fatigue and dizziness. How to solve the convergence conflict problem has become an urgent problem to be solved. This problem can be solved by monocular light field display, but the resolution is low.

Summary of the invention

In order to solve the above technical problems, the present disclosure provides a light field display device to solve the problem of how to improve the resolution while solving the convergence conflict problem.

In order to achieve the above-mentioned purpose, the technical solution adopted in the embodiment of the present disclosure is: a light field display device, which includes

A display panel having a plurality of sub-pixels arranged in an array for emitting a plurality of light rays having different image information;

A first optical element, located at the light-emitting side of the display panel, is used to make the multiple light rays emitted by the display panel form multiple virtual viewpoints that can be focused by a single eye;

The second optical element is arranged on a side of the first optical element away from the display panel, and is used to modulate the light emitted from the first optical element to form multiple viewpoints entering the human eye, so as to improve the resolution of the viewpoints.

Optionally, the second optical element is a lens, and the focal length F of the lens is obtained by the following formula: Wherein, FOV is the field of view, and PanelSize is the size (width or length) of the display panel.

Optionally, the lens may be a spherical lens, an aspherical lens, a folded light path lens or a Fresnel lens.

Optionally, the first optical element comprises a microlens array.

Optionally, the first optical element includes a first column lens unit and a second column lens unit overlapped in the light emitting direction of the display panel, the first column lens unit includes a plurality of column lenses arranged along a first direction, the second column lens unit includes a plurality of column lenses arranged along a second direction, and there is an angle between the first direction and the second direction.

Optionally, the field angle θ of the microlens or the cylindrical lens satisfies the following formula:

Optionally, the aperture D of the microlens is n*p, where n is the number of viewpoints and p is the pitch of sub-pixels.

Optionally, the focal length f of the microlens is determined according to the following formula: Wherein, θ is the field angle of the microlens or the cylindrical lens, and D is the aperture of the microlens;

The distance between the display panel and the microlens or the cylindrical lens is the focal length of the microlens or the cylindrical lens.

Optionally, a distance a between the first cylindrical lens unit or the second cylindrical lens unit and the lens satisfies the following formula: Wherein, F is the focal length of the lens, b is the depth of field corresponding to the first cylindrical lens unit or the second cylindrical lens unit, and the b value is between 500-1500 mm.

Optionally, the diameter of a single viewpoint is smaller than the distance between two adjacent viewpoints.

The beneficial effect of the present disclosure is that: by setting the first optical element, the convergence conflict problem can be solved by time monocular focusing, and the first optical element and the second optical element can improve the resolution of the viewpoint of the entering person.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram showing the occurrence of convergence conflict;

FIG2 is a schematic diagram showing that the image point and the focus are at the same position without generating a convergence conflict;

FIG3 shows a first structural diagram of a light field display device in an embodiment of the present disclosure;

FIG4 shows a second structural schematic diagram of the light field display device in an embodiment of the present disclosure;

FIG5 is a schematic diagram showing a light path in an embodiment of the present disclosure;

FIG6 is a schematic diagram showing the relationship between the number of viewpoints, the size of the light spots of the viewpoints in the human eye, and the spacing between adjacent light spots;

7 is a schematic diagram showing the relationship between the depth of field of the first cylindrical lens unit and the distance between the first cylindrical lens unit and the lens, and the relationship between the depth of field of the second cylindrical lens unit and the distance between the second cylindrical lens unit and the lens.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

The convergence function will converge the sight of both eyes to the same object, and the focus function will also focus on the object at the same distance. Over time, the brain has become accustomed to the rule that the sight and focus are always in the same position. However, when watching 3D movies, the distance between the audience and the screen is unchanged, so the focal length cannot be changed. This results in the focus function not being able to focus at the same distance as the convergence function as usual. This breaks the long-standing rule and makes the positions of convergence and focus different. The positions of the left and right eyes are separated, which is the convergence-accommodation conflict. Due to the convergence-accommodation conflict, the brain must be forced to synthesize information that the sight and focus are not in the same position, which will cause confusion in the brain, and adverse reactions such as visual fatigue, dizziness, and headaches will occur over a long period of time. Referring to Figure 1, the left eye watches the actual luminous point A on the screen, and the right eye watches the actual luminous point B on the screen. The image point fused by the left and right eyes is M. The focus position of the left and right eyes is different from the fusion position, resulting in a focus-convergence conflict.

The solution to the convergence conflict can be achieved through a monocular light field, so that the image point and the focus coincide. Referring to Figure 2, the left eye watches the image point M, and the fusion (two viewpoints) is achieved through the two pixels on the display panel. The right eye watches the image point N, and the fusion (two viewpoints) is achieved through the two pixels on the display panel. The left and right eyes focus on the image points M and N respectively, so there is no convergence conflict. However, one refers to a light field display solution based on a microlens array, which mainly uses a microlens array to collimate the light emitted by each pixel on the display panel into a light ray, generating a light field, and using this light field to simulate and restore the countless light rays in the real world to achieve light field display. Since the more light rays are restored, the better the display effect will be, but the higher the resolution of the display panel, the more light rays can be restored. Therefore, this light field display solution requires the display panel to have a very high resolution. Furthermore, since each light ray is collimated by a microlens, that is, the diameter of the light ray is the aperture of the microlens, the resolution of the two-dimensional image displayed by the display panel is also the aperture of the microlens, which makes the display resolution of this technology low and the three-dimensional display effect poor.

In view of the above problems, this embodiment provides a light field display device, which includes

A plurality of virtual viewpoints that can be focused by a single eye are formed by the first optical element, that is, one pupil can obtain at least two images with a three-dimensional display effect, and the focusing distance of one pupil for at least two images obtained through at least two viewpoints within the visible range of the pupil is equal to the visual distance when two pupils respectively obtain images with a three-dimensional effect through at least two viewpoints within the visible range of the corresponding pupils. The line convergence distance is consistent, thereby solving the problem of dizziness and discomfort of the observer in the parallax 3D technology. And through the cooperation of the first optical element and the second optical element, the resolution of the viewpoint entering the human eye is improved.

In an exemplary embodiment, the display panel may include, but is not limited to, any one of a liquid crystal display (LCD) panel, an organic light emitting diode (OLED) display panel, a light emitting diode (LED) display panel, a quantum dot light emitting diode (QLED) display panel, and a digital light processing (DLP) display panel. Of course, the display panel may also be other display panels, such as a micro light emitting diode (Micro LED) display panel, a sub-millimeter light emitting diode (Mini LED) display panel, a micro organic light emitting diode (Micro OLED) display panel, or a liquid crystal on silicon (LCOS) display panel. Here, the embodiment of the present disclosure does not limit the type of the display panel, and it can be set arbitrarily.

In an exemplary embodiment, the first optical element is a microlens array, and the microlens can be a spherical lens, an aspherical lens, a Pancake folded optical path lens or a Fresnel lens. The number and surface shape of the microlenses are set according to software optimization.

Referring to Figures 3 and 4, in an exemplary embodiment, the first optical element is a first cylindrical lens unit 4 and a second cylindrical lens unit 6 stacked in the light emitting direction of the display panel, the first cylindrical lens unit 4 includes a plurality of cylindrical lenses arranged along a first direction, the second cylindrical lens unit 6 includes a plurality of cylindrical lenses arranged along a second direction, and there is an angle between the first direction and the second direction.

Exemplarily, the first direction is perpendicular to the second direction, the cylindrical lenses in the first cylindrical lens unit 4 are extended along a direction perpendicular to the first direction, and the cylindrical lenses in the second cylindrical lens unit 6 are extended along a direction perpendicular to the second direction. Exemplarily, the first cylindrical lens unit 4 is used to collimate the sub-pixels arranged along the first direction and form a virtual viewpoint that can be focused on by a single eye. The second cylindrical lens unit 6 is used to collimate the sub-pixels arranged along the second direction and form a virtual viewpoint that can be focused on by a single eye.

In an exemplary embodiment, the second optical element 9 is a lens, and the lens may be a spherical lens, an aspherical lens, a Pancake folded optical path lens or a Fresnel lens.

In an exemplary embodiment, the display panel is an OLED flexible display panel, comprising a substrate 1 made of silicon material, a TFT array substrate 2 is arranged on the substrate 1, an RGB color light-emitting layer 3 is formed on the TFT array substrate 2, an encapsulation layer 7 is arranged on the side of the light-emitting layer 3 away from the substrate 1, the first column lens unit 4, the second column lens unit 6 and the lens (i.e., the second optical element 9) are stacked on the side of the encapsulation layer 7 away from the substrate 1, an OC flat layer 5 is filled between the first column lens unit 4 and the second column lens unit 6, a transparent spacer layer 8 is arranged between the lens and the second column lens unit 6, and the transparent spacer layer 8 can be made of transparent glass, but is not limited thereto. The lens can cover at least one column lens in the first column lens unit 4 and at least one column lens in the second column lens unit 6. Exemplarily, one lens is arranged in the light field display device, that is, the lens fully covers the first column lens unit 4 and the second column lens unit 6, but is not limited thereto.

Exemplarily, the second optical element 9 is a lens, and the focal length F of the lens is obtained by the following formula: Wherein, FOV is the field of view, and PanelSize is the width or length of the display panel.

In an exemplary embodiment, the field of view angle is 60 degrees, the size of the display panel is 0.9 inches (ie, the diagonal length of the display panel = 22.86 mm), and the width of the display panel in the first direction is 16.1 mm (ie, PanelSize is 16.1 mm), then the corresponding focal length of the lens is 14 mm.

It can be seen from Figure 5 that the second optical element 9 converges the light emitted from the first optical element, and the distance between the virtual viewpoint formed by the first optical element and the second optical element 9 is L′, and the distance between the viewpoint entering the human eye 30 formed by the second optical element and the second optical element is Ie. Obviously, L′ is greater than Ie. It can be obtained from Figure 5 that the width of the area occupied by the three virtual viewpoints formed by the first optical element is E, and the width of the area occupied by the three viewpoints entering the human eye 30 formed by the second optical element is e. Obviously, E is greater than e, that is, the distance between adjacent viewpoints is shortened, and the number of viewpoints entering the human eye is increased, thereby improving the resolution and providing more depth of field.

Exemplarily, the field angle θ of the microlens or the cylindrical lens satisfies the following formula:

Exemplarily, the aperture of the microlens is D=n*p, where n is the number of viewpoints and p is the number of sub-pixels. spacing.

It should be noted that when the first optical element is a stacked first cylindrical lens unit 4 and a second cylindrical lens unit 6 , D is the width of the cylindrical lens in the first cylindrical lens unit 4 or the cylindrical lens in the second cylindrical lens unit 6 .

The size of the display panel is 0.9 inches, and the resolution is 3840*3840. The sub-pixel size on the display panel is 2.8*2.1um, and the pixel opening rate is 30%. In order to make a single eye box (i.e., the eye box refers to a conical area between the optical display device and the eyeball, which is also the area where the display content is clearest) have as many viewpoints as possible to provide more depth of field, it is necessary to ensure that the eye spot of a single viewpoint is smaller than the spacing between two adjacent spots. In some embodiments, the number of viewpoints is preferably 2 to 20. Referring to Figure 6, the horizontal axis in Figure 6 is the number of viewpoints, the vertical axis is the numerical value, the curve 100 is the size of the spacing between the spots formed by adjacent viewpoints in the human eye, and the curve 200 is the size of the spot formed by the viewpoint in the human eye.

Exemplarily, the number of viewpoints formed by a single eye is 5, the focal length of the lens is 10 mm, and the eye box is 4 mm, then the aperture D of the microlens or the cylindrical lens is 5*2.8=14 um.

Exemplarily, the focal length f of the microlens is determined according to the following formula: Wherein, θ is the field angle of the microlens or the cylindrical lens, and D is the aperture of the microlens;

It should be noted that when the first optical element is a stacked first cylindrical lens unit 4 and a second cylindrical lens unit 6, the focal length f of the cylindrical lens in the first cylindrical lens unit 4 or the second cylindrical lens unit 6 is determined according to the following formula: Wherein, θ is the field angle of the microlens or the cylindrical lens, and D is the width of the cylindrical lens.

Exemplarily, when the first optical element is a microlens array, the distance between the light-emitting surface of the display panel and the first optical element is the focal length of the microlens; when the first optical element is a stacked first cylindrical lens unit 4 and a second cylindrical lens unit 6, the distance between the light-emitting surface of the display panel and the first cylindrical lens unit 4 disposed near the display panel is the focal length of the first cylindrical lens unit 4. distance.

It should be noted that when the medium between the display panel and the first optical element is air, the distance between the display panel and the first optical element is f. If the medium is not air, the distance between the display panel and the first optical element is 2f/n, where n is the refractive index of the medium.

In an exemplary embodiment, the focal length f of the cylindrical lens in the first cylindrical lens unit 4 is 35 um, and the medium between the display panel and the first optical element is OC (optical glue), and the refractive index of the optical glue is 1.6.

For example, the focal length of the cylindrical lens of the first cylindrical lens unit 4 or the second cylindrical lens unit 6 can be used to determine the radius of curvature of the cylindrical lens, and the arch height of the cylindrical lens can be determined in combination with the aperture of the cylindrical lens.

The refractive index of the material of the commonly used cylindrical lens is about 1.62. The focal length formula of a single lens is Since only one side of the cylindrical lens has curvature and the other side is a plane, that is, the curvature radius R2 is infinite, the focal length formula of a single cylindrical lens can be simplified to: r=f*Δn=35*0.62=21.7um, then the curvature radius r (ie R1) of the cylindrical lens is 21.7um.

If the cylindrical lens aperture D is 14um, and the arch height H = r-(r^2-(D/2)^2)^0.5, the arch height of the cylindrical lens is 1.2um. The thickness of the flat layer 5 between the first cylindrical lens unit 4 and the second cylindrical lens unit 6 is set to 2um, and the equivalent placement height of the second cylindrical lens unit 6 away from the display panel is the height of the second cylindrical lens unit 6 + the thickness of the flat layer 5 + the equivalent placement height of the first cylindrical lens unit 4 = 1.62*1.2+1.6*2+35=40.144um (the equivalent placement height of the first cylindrical lens unit 4 is 35um, the refractive index of the flat layer is 1.6, and the refractive index of the cylindrical lens in the second cylindrical lens unit 6 is 1.62), then the equivalent placement height of the second cylindrical lens unit 6 is 40.144um.

Exemplarily, the second cylindrical lens unit 6 is preferably made of a material with a low refractive index, such as a refractive index of 1.5. The diameter of the cylindrical lens in the second cylindrical lens unit 6 is consistent with the diameter of the cylindrical lens in the first cylindrical lens unit 4, which is 14um. The corresponding curvature radius is 20.072um, the arch height is 1.26um, and the calculation process is the same as above.

Exemplarily, the distance a between the first cylindrical lens unit 4 or the second cylindrical lens unit 6 and the lens (ie, I _d in FIG. 5 , I _p in FIG. 5 represents the distance between the lens and the display panel) satisfies the following formula: Wherein, F is the focal length of the lens, b is the first cylindrical lens The depth of field corresponding to the unit 4 or the second cylindrical lens unit 6 has a b value between 500 and 1500 mm.

It should be noted that, since the first cylindrical lens unit 4 and the second cylindrical lens unit 6 are stacked, the distance between the first cylindrical lens unit 4 and the lens is different from the distance between the second cylindrical lens unit 6 and the lens. At this time, it is necessary to consider the depth of field surface obtained by modulating the light of the first cylindrical lens unit 4 and the depth of field surface obtained by modulating the light of the second cylindrical lens unit 6. In order to make the difference between the depth of field surface obtained by modulating the light of the first cylindrical lens unit 4 and the depth of field surface obtained by modulating the light of the second cylindrical lens unit 6 as small as possible, the preferred depth of field range is 500mm to 1500mm.

Assuming that the distance a between the lens and the second column lens unit 6 and the distance a′ between the lens and the first column lens unit 4 are large, when the difference between a and a′ is larger than the difference between a, the distance between the first column lens unit 4 and the second column lens unit 6 can be ignored. Exemplarily, the value of a is between 13.63 mm and 13.87 mm, and the difference between a and a′ is 5 um, but it is not limited thereto. FIG. 7 shows the relationship between the depth of field of the first column lens unit 4 and the distance between the first column lens unit 4 and the lens, and the relationship between the depth of field of the second column lens and the distance between the second column lens unit 6 and the lens. In FIG. 7, the horizontal axis is the distance between the first column lens unit 4 or the second column lens unit 6 and the lens, and the vertical axis represents the depth of field corresponding to the first column lens unit 4 or the second column lens unit 6. Curve 300 is the relationship between the depth of field of the second column lens unit 6 and the distance between the second column lens unit 6 and the lens, and curve 400 is the relationship between the depth of field of the first column lens unit 4 and the distance between the first column lens unit 4 and the lens.

For example, when the second optical element 9 is a lens, the aperture of the lens is Wherein, Eye relief refers to the distance between the eye and the light field display device, and FOV is the field of view of the lens.

It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

A light field display device, comprising

A display panel having a plurality of sub-pixels arranged in an array for emitting a plurality of light rays having different image information;

A first optical element, located at the light-emitting side of the display panel, is used to make the multiple light rays emitted by the display panel form multiple virtual viewpoints that can be focused by a single eye;

The second optical element is arranged on a side of the first optical element away from the display panel, and is used to modulate the light emitted from the first optical element to form multiple viewpoints entering the human eye, so as to improve the resolution of the viewpoints.
The light field display device according to claim 1, wherein the second optical element is a lens, and the focal length F of the lens is obtained by the following formula: Wherein, FOV is the field of view, and PanelSize is the length of the diagonal of the display panel.
The light field display device according to claim 2, wherein the lens can be a spherical lens, an aspherical lens, a folded light path lens or a Fresnel lens.
The light field display device according to claim 2, wherein the first optical element comprises a microlens array.
The light field display device according to claim 2, wherein the first optical element includes a first cylindrical lens unit and a second cylindrical lens unit stacked in the light emitting direction of the display panel, the first cylindrical lens unit includes a plurality of cylindrical lenses arranged along a first direction, the second cylindrical lens unit includes a plurality of cylindrical lenses arranged along a second direction, and an angle is formed between the first direction and the second direction.
The light field display device according to claim 4 or 5, wherein the field angle θ of the microlenses in the microlens array or the cylindrical lenses satisfies the following formula:
The light field display device according to claim 6, wherein the aperture D of the microlens is n*p, where n is the number of viewpoints and p is the pitch of sub-pixels.
The light field display device according to claim 7, wherein the focal length f of the microlens is based on The following formula determines: Wherein, θ is the field of view angle of the microlens, and D is the aperture of the microlens;

The distance between the display panel and the microlens or the cylindrical lens is the focal length of the microlens or the cylindrical lens.
The light field display device according to claim 5, wherein the distance a between the first cylindrical lens unit or the second cylindrical lens unit and the lens satisfies the following formula: Wherein, F is the focal length of the lens, b is the depth of field corresponding to the first cylindrical lens unit or the second cylindrical lens unit, and the b value is between 500-1500 mm.
The light field display device according to claim 1, wherein a diameter of a single viewpoint is smaller than a distance between two adjacent viewpoints.