KR20210075363A - Waveguide display structure for extended field of vision using non-planar partial reflector array - Google Patents

Abstract

Provided is a waveguide display structure of an extended visual field, which can provide a clear image for a collimated waveguide even without an additional optical element by implementing an outer coupler of a waveguide as a partial reflective surface array based on a spherical/aspherical/free curved surface rather than a plane. According to an embodiment of the present invention, the waveguide display structure of an extended visual field comprises: a display; a collimating lens for collimating light emitted from the display into parallel light; a waveguide substrate formed in a structure having two or more main surfaces parallel to each other, and guiding incident collimated light; an inner coupler for allowing the collimated light passing through the collimating lens to be incident into the waveguide substrate; and an outer coupler having a partial reflective surface to emit the collimated light transmitted to the waveguide substrate. The incident collimated light is partially reflected and output from each outer coupler, such that a waveguide display of an extended exit pupil is finally formed. Accordingly, distribution of rays from the depth where an observation is easy can be expressed even only with a waveguide, such that an additional concave lens (or a pair of a concave lens and a convex lens) can be excluded from use. Therefore, the entire thickness, volume, and weight of an optical system can be reduced, and the productivity of an optical component can be improved.

Description

TECHNICAL FIELD [0002] Waveguide display structure for extended field of vision using non-planar partial reflector array

The present invention relates to a waveguide display structure, and more particularly, by implementing the outcoupler of the waveguide as a partial reflective surface array based on a spherical/aspherical/free-form surface rather than a planar surface, a clear image for collimated waveguide light without additional optical elements It relates to a field-of-view extension waveguide display structure that can provide.

In general, collimated light collimated with light incident on the waveguide and light emitted from the waveguide is used to facilitate design of the waveguide display and prevent crosstalk within the observation angle of view.

However, since the image emitted as parallel light generally does not form an imaging plane that can be easily observed by the user, an additional optical element (concave lens, etc.) having a separate curvature between the waveguide and the user's pupil is additionally utilized. Therefore, it is necessary to make an effort to form the observation image at a distance of about 2m to 3m.

That is, in the waveguide display using the partial reflective surface array, as shown in FIG. 1 , the display pixels outside the waveguide are collimated with parallel light through a collimating lens, and then into the waveguide substrate through an in-coupler using a flat mirror or prism. The waveguided light propagated by total reflection is reflected by an outcoupler array composed of a planar partially reflecting surface and partially emitted, and the viewing area can be widened by expanding the exit pupil in proportion to the number of reflecting surfaces. However, when the user directly observes collimated light at a high level, the focus is not clearly defined and the resolution is felt as if it is lowered, so an additional optical element (concave lens) with a separate curvature between the waveguide and the user There is a disadvantage in that the collimated light emitted by using a should be changed to feel like a divergent light originating from a specific observation depth (2m - 3m level).

In addition, in order to prevent the actual image from being distorted due to the concave lens, a convex lens having a similar curvature must be additionally mounted on the opposite side of the concave lens with respect to the waveguide. These additional optical elements require a thickness similar to that of the waveguide (1-5 mm) due to processability, etc., and thus have a limit in increasing the thickness of the entire optical system.

That is, due to the mounting of two additional lenses, the waveguide display is inevitably thicker than the thickness of the waveguide itself, and an increase in weight and cost due to the introduction of the additional lens is also a problem.

The present invention has been devised to solve the above problems, and an object of the present invention is to transmit emitted light from each pixel incident and guided as parallel light through a non-planar partial reflective surface array divided according to an outcoupler position. It is to provide a viewing area extension type waveguide display structure using a non-planar partial reflective surface array that realizes the same divergent light as emitted from a depth (2m-3m) that is easy to observe without a separate concave lens.

According to an embodiment of the present invention for achieving the above object, a viewing area extension waveguide display structure includes a display; a collimating lens for collimating the light emitted from the display into parallel light; a waveguide substrate formed in a structure having two or more main surfaces parallel to each other and guiding the incident collimated light; an in-coupler for entering the collimated light passing through the collimating lens into the waveguide substrate; and an outcoupler having a partially reflective surface and outputting the collimated light transmitted to the waveguide substrate; in this case, the incident collimated light is partially reflected and emitted by each outcoupler, thereby finally exiting the exit pupil (exit) pupil) so that a waveguide display of an extended type is configured.

In addition, each of the outcouplers may have a partially reflective surface configured as a curved surface to replace the image forming surface forming role, which is the role of the concave lens.

In addition, in the viewing area extension type waveguide display structure, by replacing the concave lens through each outcoupler, for the simplification of the structure, it may be possible to omit the concave lens for forming the imaging plane and the convex lens for preventing distortion of the actual image. .

) 및 입사각도에 의해 반사되는 각도(

)는, 비축(Off-axis) 형태의 구면 거울의 곡면을 차용하며, 중심 픽셀의 시준광이 도파되어 오는 도파각도가

이고, 중심에서 그은 접선이 도파관의 기판면과 이루는 각도가

인 경우, 하기 수식 1을 이용하여 산출할 수 있다. And the incident angle of the waveguide at the center point of the outcoupler (

) and the angle reflected by the angle of incidence (

) borrows the curved surface of an off-axis type spherical mirror, and the waveguide angle at which the collimated light of the central pixel is guided is

and the angle formed by the tangent line drawn from the center to the substrate surface of the waveguide is

In the case of , it can be calculated using Equation 1 below.

(Formula 1)

In addition, the outcoupler adjacent to the center outcoupler may be formed with the same radius of curvature as the center outcoupler, and may be composed of a spherical partial reflective surface having a center of curvature moved up or down by the thickness of the waveguide.

In addition, the non-planar reflective surface of the outcoupler may be formed in an aspherical shape or a free-form surface shape rather than a perfect spherical surface to prevent aberration that may occur in the spherical partial reflective surface when the partial reflective surface is formed as a spherical surface.

의 각도를 가지고 기울어지도록 형성될 수 있다. In addition, the aspherical partial reflective surface of the outcoupler is formed with the lower surface of the waveguide and

It may be formed to be inclined with an angle of .

On the other hand, according to another embodiment of the present invention, a viewing area extension type waveguide display method includes: collimating light emitted from the display into parallel light through a collimating lens; injecting the collimated light passing through the collimating lens through the in-coupler into a waveguide substrate formed in a structure having two or more main surfaces parallel to each other; and outputting the collimated light incident into the waveguide substrate through an outcoupler having a partially reflective surface; in this case, the incident collimated light is partially reflected and emitted by each outcoupler to finally be used Allows a waveguide display with an extended exit pupil to be configured.

As described above, according to the embodiments of the present invention, the waveguide itself can express the distribution of rays coming from a depth that is easy to observe, so it is possible to exclude the use of an additional concave lens (or a concave lens + a convex lens pair), Through this, it is possible to reduce the overall thickness, volume, and weight of the optical system, as well as help improve the productivity of optical components.

1 is a view provided for the description of a waveguide display structure based on a conventional planar partially reflective surface;
2 is a view provided for explanation of a field-of-view extended waveguide display structure utilizing a non-planar partially reflective surface array according to an embodiment of the present invention;
3 is a view provided for explanation of the imaging characteristics of incident parallel light on a spherical reflective surface;
4 to 5 are views provided for explanation of the curvature center characteristic for each reflective surface of the spherical reflective surface array constituting the outcoupler;
6 to 7 are views provided for explanation of an aspherical partially reflective surface array according to another embodiment of the present invention;
8 is a view provided for explanation of a field-of-view extension type waveguide display method using a non-planar partial reflective surface array according to an embodiment of the present invention.

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

2 is a view provided for explanation of a field-of-view extended waveguide display structure using a non-planar partial reflective surface array (hereinafter, collectively referred to as a 'view-field extended waveguide display structure') according to an embodiment of the present invention, FIG. 3 is a view provided for the description of the imaging characteristics of the incident parallel light on the spherical reflective surface, and FIGS. 4 to 5 are views provided for the explanation of the curvature center characteristic for each reflective surface of the spherical reflective surface array constituting the outcoupler .

The waveguide display is located in front of the user's pupil and an in-coupler that injects light from the display located on the user's side or upper surface into the waveguide substrate having two or more main surfaces parallel to each other. It consists of an out-coupler that emits the transmitted light. At this time, the in/out coupler may be composed of a diffractive optical element, a holographic optical element, a reflective surface, a partially reflective surface, etc. Since the light transmitted through the inside of the waveguide substrate is due to total reflection, a long waveguide without a separate reflective coating can spread the distance.

The field-of-view extension type waveguide display structure according to an embodiment of the present invention, particularly in a waveguide display having an outcoupler structure in which a plurality of partial reflection surfaces are arranged in an array form, each reflection surface is a curved surface (spherical surface, aspherical surface, free-form surface, etc.) By proposing an optical structure composed of It is possible to implement the same divergent light as emitted from one depth.

Specifically, the present viewing area extension type waveguide display structure uses the collimated pixel light as it is, as shown in FIG. 2, but by transforming the outcoupler into a non-planar shape, a user can easily do it without using a separate concave/convex lens It is an optical structure of a waveguide display capable of observing an image.

At this time, when the collimated light passing through the collimating lens collimating into the collimated light is incident into the waveguide substrate, the incident collimated light is composed of a curved mirror and meets the partially reflective coated outcoupler array. The light is partially reflected from the coupler, and finally, an exit pupil is expanded to constitute a waveguide display.

However, since the partial reflection surface of each outcoupler is configured as a curved surface, the outcoupler itself can take over the role of forming the image forming surface that the concave lens did in FIG. 1 , thereby simplifying the overall structure.

In addition, as the concave lens becomes unnecessary, the convex lens for preventing distortion of the actual image can also be removed, thereby simplifying the entire waveguide display structure and helping to improve productivity.

That is, each outcoupler has a partially reflective surface configured as a curved surface to replace the image forming surface forming role, which is the role of the concave lens, and the viewing area extension type waveguide display structure replaces the concave lens through each outcoupler, For the simplification of the structure, it is possible to omit the concave lens for forming the imaging plane and the convex lens for preventing distortion of the actual image.

FIG. 3 shows a principle of using a spherical mirror surface as an example of a partially reflective surface of a curved surface.

) 및 입사각도에 의해 반사되는 각도(

)는, 비축(Off-axis) 형태의 구면 거울의 곡면을 차용하며, 중심 픽셀의 시준광이 도파되어 오는 도파각도가

이고, 중심에서 그은 접선이 도파관의 기판면과 이루는 각도가

인 경우, 하기 수식 1을 이용하여 산출할 수 있다. The incident angle of the waveguide at the center point of the outcoupler (

) and the angle reflected by the angle of incidence (

) borrows the curved surface of an off-axis type spherical mirror, and the waveguide angle at which the collimated light of the central pixel is guided is

and the angle formed by the tangent line drawn from the center to the substrate surface of the waveguide is

In the case of , it can be calculated using Equation 1 below.

(Formula 1)

Assuming that the boundary points where the outcoupler meets the waveguide having a finite size are A and B, respectively, the beam reflected through the outcoupler is a divergence with a larger beamwidth than the distance between the points A and B. transformed into a spherical wave.

The observer recognizes the virtual start point of the spherical wave as the imaging position of the corresponding pixel, and in this case, the depth of the imaging plane may satisfy a level similar to the distance to the center of curvature of the spherical surface.

In configuring a plurality of outcouplers in an array form, the radius of curvature of each outcoupler is the same, but the coordinates of the center of curvature may be set differently.

4 to 5 show a method of determining a center of curvature of each outcoupler as one embodiment implemented with three outcouplers.

First, the radius of curvature and the center of curvature of the spherical partial reflective surface are derived based on the central outcoupler.

The outcoupler adjacent to the center outcoupler is formed with the same radius of curvature as the center outcoupler, and is composed of a spherical partial reflective surface having a center of curvature shifted up or down by the thickness of the waveguide.

For better understanding, the three outcouplers can be modeled as shown in FIG. 5 by stacking them along the propagation direction of the waveguide. That is, it can be understood that the function of _{the convex mirror performed by the curve C 0} , which is the entire spherical partial reflection surface _{, is divided into C 1} , C ₂ , and C ₃ according to the position in each outcoupler to perform the function.

6 to 7 are views provided for explanation of an aspherical partial reflective surface array according to another embodiment of the present invention.

6 to 7, the non-planar reflective surface of the outcoupler according to the present embodiment is not a perfect spherical surface to prevent aberration that may occur in the spherical partial reflective surface when the partial reflective surface is formed of a spherical surface. It may be formed in an aspherical shape or a free-form surface shape.

의 각도를 가지고 기울어지도록 형성되며, 중심 아웃커플러의 중앙에서 거리 r 만큼 떨어진 지점에서의 표면 Sag는 다음과 같이 비구면 표현식을 따를 수 있다. 이때, R은 곡률 반경, K는 conic constant, α _i는 비구면 계수이다.The aspherical partial reflective surface of the outcoupler is separated from the lower surface of the waveguide

It is formed to be inclined with an angle of , and the surface Sag at a distance r away from the center of the center outcoupler can follow the aspherical expression as follows. Here, R is the radius of curvature, K is the conic constant, and α _i is the aspheric coefficient.

(aspherical expression)

FIG. 8 is a view provided for explaining a method for displaying a field-of-view extended waveguide using a non-planar partially reflective surface array according to an embodiment of the present invention. Referring to FIG. 8 , the viewing area extension type waveguide display method using the non-planar partial reflective surface array according to the present embodiment includes a collimating step (S810) of collimating light emitted from the display into parallel light through a collimating lens, an in-coupler Through the incident step (S820) of injecting the collimated light passing through the collimating lens into the waveguide substrate, and through the outcoupler provided with the partial reflection surface, into the waveguide substrate formed in a structure having two or more main surfaces parallel to each other It may be composed of a light exit step (S830) of outputting the incident collimated light.

In this case, the incident collimated light may be partially reflected and emitted by each outcoupler, thereby finally configuring a waveguide display in which an exit pupil is expanded.

Through this, the emitted light of each pixel incident and guided as parallel light is emitted through the non-planar partial reflective surface array divided according to the outcoupler position, and through this, it is emitted at a depth that is easy to observe without a separate concave lens. The same divergent light can be implemented.

On the other hand, it goes without saying that the technical idea of the present invention can also be applied to a computer-readable recording medium containing a computer program for performing the functions of the apparatus and method according to the present embodiment. In addition, the technical ideas according to various embodiments of the present invention may be implemented in the form of computer-readable codes recorded on a computer-readable recording medium. The computer-readable recording medium may be any data storage device readable by the computer and capable of storing data. For example, the computer-readable recording medium may be a ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical disk, hard disk drive, or the like. In addition, the computer-readable code or program stored in the computer-readable recording medium may be transmitted through a network connected between computers.

In addition, although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention as claimed in the claims Various modifications are possible by those of ordinary skill in the art, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

110: display
120: collimating lens
130: waveguide substrate
140: in-coupler
150: out coupler
151: partially reflective surface

Claims (8)

display;
a collimating lens for collimating the light emitted from the display into parallel light;
a waveguide substrate formed in a structure having two or more main surfaces parallel to each other and guiding the incident collimated light;
an in-coupler for entering the collimated light passing through the collimating lens into the waveguide substrate; and
an outcoupler having a partially reflective surface to emit collimated light transmitted to the waveguide substrate;
The incident collimated light is
A view area extension type waveguide display structure, characterized in that by being partially reflected and emitted from each outcoupler, a waveguide display having an extended exit pupil is finally configured.
The method according to claim 1,
Each outcoupler is
A viewing area extension type waveguide display structure, characterized in that the partially reflective surface is configured as a curved surface to replace the role of the concave lens for forming an imaging surface.
3. The method according to claim 2,
The viewing area extension type waveguide display structure is,
By replacing the concave lens through each outcoupler, for the simplification of the structure, it is possible to omit the concave lens for forming the imaging surface and the convex lens for preventing real-world distortion.
3. The method according to claim 2,
The incident angle of the waveguide at the center point of the outcoupler (

) and the angle reflected by the angle of incidence (

) is,
It borrows the curved surface of the off-axis type spherical mirror, and the waveguide angle at which the collimated light of the central pixel is guided is

and the angle formed by the tangent line drawn from the center to the substrate surface of the waveguide is

In the case of , it is characterized in that calculated using the following Equation 1, the extended type waveguide display structure.
(Formula 1)

3. The method according to claim 2,
The outcoupler adjacent to the center outcoupler,
A viewing area extension type waveguide display structure comprising a spherical partial reflective surface formed with the same radius of curvature as the center outcoupler, and having a center of curvature moved up or down by the thickness of the waveguide.
The method according to claim 1,
The non-planar reflective surface of the outcoupler is,
A viewing area extension type waveguide display structure, characterized in that it is formed in an aspherical shape or a free-form surface shape rather than a perfect spherical surface to prevent aberration that may occur in the spherical partial reflection surface when the partially reflective surface is formed in a spherical shape.
7. The method of claim 6,
The aspherical partial reflective surface of the outcoupler is,
the lower surface of the waveguide

A viewing area extension type waveguide display structure, characterized in that it is formed to be inclined with an angle of .
collimating light emitted from the display into parallel light through a collimating lens;
injecting the collimated light passing through the collimating lens through the in-coupler into a waveguide substrate formed in a structure having two or more main surfaces parallel to each other; and
Including; outputting the collimated light incident into the waveguide substrate through the outcoupler provided with the partially reflective surface;
The incident collimated light is
A method for displaying a waveguide for extended viewing area, characterized in that by partially reflecting light from each outcoupler, a waveguide display with an extended exit pupil is finally configured.

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