WO2023128168A1

WO2023128168A1 - Compact augmented reality optical device using embedded collimator and optical element having negative refractive index

Info

Publication number: WO2023128168A1
Application number: PCT/KR2022/015362
Authority: WO
Inventors: 하정훈
Original assignee: 주식회사 레티널
Priority date: 2021-12-28
Filing date: 2022-10-12
Publication date: 2023-07-06
Also published as: KR20220006023A

Abstract

The present invention provides a compact augmented reality optical device using an embedded collimator and an optical element having a negative refractive index, the augmented reality optical device comprising: a first optical element for converting virtual image video light emitted from a video emitter into collimated parallel light and transferring same to a second optical element; a second optical element for transferring the virtual image video light transferred from the first optical element to a third optical element; a third optical element for transferring the virtual image video light transferred from the second optical element to a user's pupils, thereby providing the user with a virtual image, the third optical element transmitting an actual object video image emitted from a real-world object and transferring same to the user's pupils; and an optical means on which the first, second, and third optical elements are disposed, and which transmits an actual object video image emitted from a real-world object and transferring same to the user's pupils. The third optical element is an optical element having a negative refractive index such that virtual image video light is refracted in a direction symmetric to the refractive direction of light having a positive refractive index with regard to the normal of an emission surface.

Description

Optical device for compact augmented reality with built-in collimator and negative refraction optical element

The present invention relates to an optical device for augmented reality, and more particularly, to a compact augmented reality capable of reducing a form factor while widening an eyebox and a field of view (FOV) by using a built-in collimator and a negative refraction optical element. It is about an optical device for use.

As is well known, augmented reality (AR) refers to virtual image information augmented from visual information of the real world by overlapping a virtual image provided by a computer or the like with a real image of the real world. It refers to technology that is simultaneously provided to users.

An apparatus for realizing such augmented reality requires an optical combiner that enables simultaneous observation of virtual images and real images in the real world. As such an optical synthesizer, a half mirror method and a holographic/diffractive optical element (HOE/DOE) method are known.

The semi-mirror method has a problem in that the transmittance of the virtual image is low and it is difficult to provide a comfortable fit because the volume and weight are increased to provide a wide viewing angle. In order to reduce the volume and weight, a technology such as a so-called LOE (Light guide Optical Element) in which a plurality of small half mirrors are placed inside a waveguide has also been proposed, but this technology also has a half mirror of a virtual image inside the waveguide. Since it has to pass through several times, the manufacturing process is complicated, and there is a limit in that light uniformity may be lowered due to errors in manufacturing.

In addition, the holographic/diffractive optical element method generally uses a nanostructured grating or a diffraction grating, and since they are manufactured in a very precise process, they have limitations in that the manufacturing cost is high and the yield for mass production is low. In addition, due to the difference in diffraction efficiency according to the wavelength band and the incident angle, it has limitations in terms of color uniformity and low sharpness of the image. Holographic/diffractive optical elements are often used with waveguides such as the LOEs described above, and thus still suffer from the same problems.

In addition, conventional optical synthesizers have limitations in that a virtual image is out of focus when a user changes a focal length when gazing at the real world. In order to solve this problem, a technique using a prism capable of adjusting the focal length of a virtual image or a variable focus lens capable of electrically controlling the focal length has been proposed. However, this technique also has a problem in that a user must perform a separate operation to adjust the focal length or require separate hardware and software for controlling the focal length.

In order to solve the problems of the prior art, the present applicant has developed a technique of projecting a virtual image onto the retina through the pupil using a reflector in the form of a pin mirror having a size smaller than that of the human pupil ( see Prior Art Document 1).

1 is a diagram showing an optical device 100 for augmented reality as described in Prior Art Document 1.

The optical device 100 for augmented reality of FIG. 1 includes an optical unit 10 , a reflection unit 20 and an image output unit 30 .

The optical means 10 functions to transmit real object image light, which is image light emitted from objects in the real world, through the pupil 40 and emit virtual image image light reflected by the reflector 20 into the pupil 40. It is a means of carrying out Inside the optical means 10, the reflector 20 is buried and disposed.

The optical means 10 may be formed of, for example, a transparent resin material such as a spectacle lens, and may be fixed by a frame (not shown) such as a spectacle frame.

The image emitting unit 30 is a means for emitting virtual image light, which displays a virtual image on a screen and outputs a virtual image image light corresponding to the displayed virtual image from a micro display device and a micro display device 31. A collimator for collimating image light into parallel light may be provided.

The reflector 20 is a means for reflecting the virtual video image light emitted from the image emitter 30 and transmitting it toward the pupil 40 of the user.

The reflector 20 of FIG. 1 is formed to have a smaller size than a human pupil. Since it is known that the size of a typical human pupil is about 4 to 8 mm, the reflector 20 is preferably formed to a size of 8 mm or less, more preferably 4 mm or less. As a result, the depth of field for the light incident to the pupil 40 through the reflector 20 can be made almost infinite, that is, very deep.

Here, the depth of field refers to a range recognized as being in focus. As the depth of field increases, the range of the focal length of the virtual image correspondingly widens. Therefore, even if the user changes the focal length of the real world while gazing at the real world, it is recognized that the focus of the virtual image is always correct regardless of this. This can be regarded as a kind of pinhole effect.

Accordingly, by forming the reflector 20 to have a smaller size than the pupil 40, the user can always observe a clear virtual image even if the user changes the focal length of the real object.

Meanwhile, the present applicant has developed a compact optical device 200 for augmented reality using a plurality of reflectors and a built-in collimator based on the basic principle of the optical device 100 for augmented reality as shown in FIG. 1 (prior art). see Literature 2).

2 to 4 are views showing an optical device 200 for augmented reality based on the technology disclosed in Prior Art Document 2, wherein FIG. 2 is a side view, FIG. 3 is a perspective view, and FIG. 4 is a front view.

The optical device 200 for augmented reality of FIGS. 2 to 4 has the same basic principle as the optical device 100 for augmented reality of FIG. It consists of modules 21 to 29 and is disposed inside the optical means 10 in the form of an array, and the collimator 80 is placed inside the optical means 10 to emit from the image ejection unit 30. The difference is that the virtual video image light is transferred to the reflection modules 21 to 29 by the collimator 80.

By arranging the collimator 80 inside the optical means 10 as described above, the optical device 200 for augmented reality of FIGS. 2 to 4 does not need to include the collimator in the image output unit 30 unlike FIG. 1 . There is no image output unit 30 can be configured only with a micro display device.

In the optical device 200 for augmented reality of FIGS. 2 to 4 , the virtual video image light emitted from the image emitting unit 30 is totally reflected on the inner surface of the optical means 10 and then transferred to the collimator 80. The virtual image image light reflected in 80 is totally reflected again on the inner surface of the optical means 10 and transmitted to the plurality of reflection modules 21 to 29, and the plurality of reflection modules 21 to 29 enter the virtual image image. The light is reflected and transmitted to the pupil 40 .

Since the optical device 200 for augmented reality provides a wide viewing angle and improves light efficiency, and uses a built-in collimator 80 inside the optical means 10 without using a collimator in the image output unit 30, the device It has the advantage of being able to reduce the overall size, thickness, weight and volume of

Meanwhile, an eyebox in the horizontal direction (x-axis direction) of the optical device 200 for augmented reality having this configuration depends on the length of the collimator 80 in the horizontal direction.

5 and 6 are views for explaining an eyebox in the horizontal direction of the optical device 200 for augmented reality, FIG. 5 is a plan view of the optical device 200 for augmented reality, and FIG. 6 is equivalent to FIG. It shows the optics.

5 and 6, the virtual video image light emitted from three points (A, B, C) to the image emitting unit 30 is transmitted to the pupil 40 through the collimator 80 and the reflecting unit 20. , and the overlapping area is indicated by hatching. The overlapped area indicated by this hatched line corresponds to the maximum eyebox area in the x-z plane.

At this time, the length of the eyebox in the horizontal direction (x-axis direction) is d2, which can be expressed by the following equation by the proportional expression of the triangle.

d2 = d1-2(y1+y2)tan(FOV/2)

Here, d1 is the length of the collimator 80, and FOV is the viewing angle. In addition, y1 is the distance from the collimator 80 to the exit pupil, that is, the reflector 20, and y2 is the distance from the reflector 20 to the pupil 40, that is, eye relief am.

Since y1 and y2 are fixed values, it can be seen that the length d2 of the eyebox in the horizontal direction is determined according to the length d1 of the collimator 80 .

This means that the length of the collimator 80 should be increased in order to widen the eyebox in the horizontal direction in the optical device 200 for augmented reality. However, there is a problem that the longer the length of the collimator 80, the more complicated the design and the more complicated the manufacturing process. In addition, as the length of the collimator 80 increases, the probability of generating a ghost image increases and the probability of blocking real object image light also increases. In addition, since it is also noticeable in appearance, the aesthetic feeling is not good. Therefore, it is necessary to minimize the length of the collimator 80 as much as possible.

[Prior art literature]

[Prior Art Document 1] Republic of Korea Patent Publication No. 10-2018-0028339 (published on March 16, 2018)

[Prior Art Document 2] Republic of Korea Patent Registration No. 10-2200144 (2021.01.08 notice)

The present invention is to solve the above problems, using a built-in collimator and a negative refractive optical element, compact augmented reality optics that can reduce the form factor while widening the eyebox and field of view (FOV) It aims to provide a device.

In addition, the present invention can simplify the design and manufacturing process by adjusting the length of the collimator built into the optical means to obtain a desired eye box and viewing angle, minimize the occurrence of ghost images and increase the transmission efficiency of real object image light. Another object is to provide an optical device for augmented reality.

In order to solve the above problems, the present invention is a compact augmented reality optical device using a negative refractive optical element, which converts virtual video image light emitted from an image output unit into collimated parallel light and transmits light to a second optical element. a first optical element that transmits; a second optical element that transmits the virtual video image light transmitted from the first optical element to a third optical element; A virtual image is provided to the user by passing the virtual image image light transmitted from the second optical element toward the pupil of the user's eye, and the real object image light emitted from the object in the real world is transmitted through the pupil of the user's eye. a third optical element that transmits; and an optical unit in which the first optical element, the second optical element, and the third optical element are disposed, and transmits real object image light emitted from a real object toward a pupil of a user's eye. An optical device for augmented reality, characterized in that the optical element is a negative refraction optical element that refracts virtual video image light in a direction symmetrical to the refracting direction of light having a positive refractive index and the normal line of the emission surface.

Here, the virtual video image light emitted from the image emitting unit is directly transferred to the first optical element through the inside of the optical means, or is totally reflected at least once on the inner surface of the optical means, and then the first optical element. can be forwarded to

In addition, the virtual video image light converted into collimated parallel light by the first optical element may be directly transmitted to the second optical element or may be transmitted to the second optical element after being totally reflected at least once on an inner surface of the optical means. .

In addition, the optical means includes a first surface through which the virtual video image light and the real object image light transmitted through the third optical element are emitted toward the user's pupil, and the first surface is opposite to the first surface and the real object image light is incident. The first optical element is a reflecting means for reflecting and emitting incident virtual video image light, and the reflecting surface of the first optical element reflects the first surface or the second surface of the optical means. It can be placed facing up.

Also, the reflective surface of the first optical element may be a concave curved surface.

In addition, the first optical element may be formed to extend closer to the image output unit toward both left and right ends from the central portion when the optical means is viewed from the pupil toward the front direction.

Also, the second optical element may be buried inside the optical means.

Also, the second optical element may be composed of a plurality of optical modules arranged in a matrix form when viewed from the front.

In addition, the second optical element may be a reflection means for reflecting and radiating incident virtual video image light.

Also, the third optical element may refract incident light in a horizontal direction when a user looks at the optical means.

Also, the third optical element may be disposed in the optical means between the second optical element and the pupil of the user's eye.

In addition, the optical means includes a first surface through which the virtual video image light and the real object image light transmitted through the third optical element are emitted toward the user's pupil, and the first surface is opposite to the first surface and the real object image light is incident. The third optical element may be disposed on an inner surface or an outer surface of the first surface of the optical means, or may be disposed between the second optical element and the second surface of the optical means. .

In addition, when the length of the eyebox in the horizontal direction observed in the pupil of the user's eye is d2, the length d1 in the horizontal direction of the first optical element is d1 = d2 + 2ABS(y1-y2)tan(FOV /2) (where FOV is the viewing angle, y1 is the distance from the first optical element to the second optical element, and y2 is the distance from the second optical element to the pupil).

Also, the second optical element may be a diffractive element.

Also, the second optical element may be a reflection type diffraction element or a transmission type diffraction element.

Also, the second optical element may be a holographic optical element (HOE).

Also, the second optical element may be a diffraction element formed in a single plane.

According to another aspect of the present invention, a compact augmented reality optical device using a negative refractive optical element, wherein a first optical device converts virtual video image light emitted from an image output unit into collimated parallel light and transfers the light to a second optical element. device; a second optical element that transmits the virtual image image light transmitted from the first optical element to the pupil of the user's eye and transmits real object image light emitted from objects in the real world to the pupil of the user's eye; and an optical unit in which the first optical element and the second optical element are disposed, and transmits real object image light emitted from a real object toward a pupil of a user's eye, wherein the second optical element comprises: Provided is an optical device for augmented reality, characterized in that it is a negative refraction diffraction element that refracts virtual video image light in a direction symmetrical with respect to the refractive direction of light having a refractive index of and the normal line of the exit surface.

According to the present invention, it is possible to provide a compact augmented reality optical device capable of reducing a form factor while widening an eyebox and a field of view (FOV) by using a built-in collimator and a negative refractive optical element.

In addition, the present invention can simplify the design and manufacturing process by adjusting the length of the collimator built into the optical means to obtain a desired eye box and viewing angle, minimize the occurrence of ghost images and increase the transmission efficiency of real object image light. An optical device for augmented reality may be provided.

7 to 9 are views for explaining an embodiment of an optical device 300 for compact augmented reality using a built-in collimator and a negative refractive optical element according to the present invention, FIG. 7 is a perspective view, FIG. 8 is a front view, 9 is a side view;

10 is a diagram for explaining the principle of a negative refractive optical element.

FIG. 11 is a diagram for explaining an eye box of the optical device 300, and shows an equivalent optical system for a plan view of the optical device 300. Referring to FIG.

12 shows a negative refraction phenomenon according to a negative refractive constant.

13 and 14 are diagrams for explaining a change in viewing angle according to a negative refractive constant.

15 shows a side view of an optical device 400 according to another embodiment of the present invention.

16 shows a side view of an optical device 500 according to another embodiment of the present invention.

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

7 to 9, a compact augmented reality optical device 300 (hereinafter simply referred to as "optical device 300") using a built-in collimator and a negative refractive optical element of the present embodiment includes an optical means 10, It includes a first optical element 80 , a second optical element 20 and a third optical element 50 .

The optical means 10 is a means for transmitting real object image light emitted from objects in the real world to the pupils 40 of the user's eyes. In addition, the first optical element 80 , the second optical element 20 , and the third optical element 50 are disposed inside the optical means 10 .

The optical means 10 includes a first surface 11 through which virtual video image light and real object image light transmitted through the third optical element 50 are emitted toward the user's pupil 40, and the first surface ( 11) and has a second surface 12 on which real object image light is incident.

In addition, the optical means 10 may include a third surface 13, which is a surface on which the virtual video image light is incident, and a fourth surface 14, which is a surface opposite to the third surface 13.

The image emitting unit 30 is means for displaying a virtual image and emitting virtual image light corresponding to the virtual image. Since the function of the collimator in the present invention is performed by the first optical element 80 built in the optical means 10 as described later, the image output unit 30 is a small-sized LCD, OLED, LCoS, or micro LED. It may be implemented as a conventionally known micro display device, such as the like.

Here, the virtual image means an image for augmented reality, and may be an image or a video. Since the image output unit 30 itself is not a direct object of the present invention and is known in the prior art, a detailed description thereof will be omitted.

In the optical device 300 of FIGS. 7 to 9 , the virtual video image light emitted from the image emitting unit 30 is totally reflected by the second surface 12 of the optical means 10 to the first optical element 80. Although shown as transmitted, this is exemplary and may be transmitted directly to the first optical element 80 without total reflection on the inner surface of the optical means 10 . In addition, it goes without saying that the total reflection may be transmitted to the first optical element 80 after being totally reflected twice or more on the inner surface of the optical means 10 .

In addition, in FIGS. 7 to 9, the image output unit 30 is shown as being disposed on the upper surface of the optical means 10, that is, above the third surface 13, but this is exemplary and may be disposed in other positions. Of course there is.

In addition, in FIGS. 7 to 9 , the image output unit 30 is disposed apart from the third surface 13 of the optical means 10, but this is exemplary and may be disposed to contact the third surface 13. Of course it can.

The first optical element 80 converts incident virtual video image light into collimated parallel light and transmits it to the second optical element 20 . Accordingly, the virtual video image light emitted from the first optical element 80 is collimated parallel light or image light for which the focal length is intended.

The first optical element 80 may be embodied as a reflector that emits collimated parallel light while reflecting incident virtual video image light. For example, the first optical element 80 may be formed of a material having a high reflectance of 100% or close to 100%, such as a metal material.

As shown in FIGS. 7 to 9 , the first optical element 80 is disposed and buried inside the optical means 10 so as to face the image output unit 30 .

As shown in FIG. 9 , the image emitting unit 30 emits virtual video image light toward the second surface 12 of the optical means 10, and the second surface 12 of the optical means 10 emits total reflection. The resulting virtual video image light is transferred to the first optical element 80. Then, the virtual video image light converted into collimated parallel light by the first optical element 80 and emitted is totally reflected again by the second surface 12 of the optical means 10 and transmitted to the second optical element 20. do. The second optical element 20 transmits incident virtual video image light to the pupil 40 through the third optical element 50 .

Therefore, the first optical element 80 emits the virtual video image light that is totally reflected from the second surface 12 of the optical means 10 and incident toward the second surface 12 of the optical means 10, and The image output unit 30, the second optical element 20, and the third optical element 30 allow augmented reality image light totally reflected by the second surface 12 of the means 10 to be transferred to the second optical element 20. Considering the relative positions of the element 50 and the pupil 40, it is disposed at an appropriate position inside the optical means 10 between the first face 11 and the second face 12 of the optical means 10.

To this end, in the embodiments of FIGS. 7 to 9 , the reflection surface 81 of the first optical element 80 that reflects the virtual video image light is the second optical element 80 of the optical means 10. It is disposed embedded inside the optical means 10 so as to face the face 12 .

Here, a straight line in a vertical direction from the center of the reflection surface 81 and the second surface 12 of the optical means 10 may be inclined so as not to be parallel to each other.

According to this arrangement structure, while the first optical element 80 emits virtual video image light toward the second surface 12, miscellaneous light emitted from a real object and capable of generating a ghost image is emitted from the pupil 40. It has the advantage of being able to block transmission to the side.

However, this is exemplary, and the reflective surface 81 of the first optical element 80 may be disposed buried inside the optical means 10 so as to face the first surface 11 of the optical means 10. is of course

Meanwhile, the reflective surface 81 of the first optical element 80 may be formed as a curved surface. For example, the reflecting surface 81 of the first optical element 80 may be a concave mirror concavely formed in the direction of the second surface 12 of the optical means 10 as shown in FIGS. 7 to 9 . With this configuration, the first optical element 80 is built into the optical means 10 and can serve as a built-in collimator for collimating virtual video image light emitted from the image output unit 30, and thus It is not necessary to use a structure such as a collimator for the image output unit 30.

In addition, it is preferable that the first optical element 80 has a thin thickness when the user looks at the front through the pupil 40 so that the user cannot recognize it as much as possible.

Meanwhile, the first optical element 80 may be configured with a means such as a half mirror that partially reflects light.

In addition, the first optical element 80 may be formed of a refraction element or a diffraction element other than a reflective element, or a combination of at least one of them.

In addition, the first optical element 80 may be formed of an optical element such as a notch filter that selectively transmits light according to a wavelength.

In addition, a surface opposite to the reflective surface 81 reflecting virtual image light of the first optical element 80 may be coated with a material that does not reflect light but absorbs it.

On the other hand, as shown in FIG. 8 , when the optical means 10 is viewed from the pupil 40 in the front direction, the image output unit 30 moves toward both left and right ends from the central portion. ) may be formed by extending to be closer to . That is, when viewed from the front, the first optical element 80 may be formed in a generally gentle "U" bar shape. Accordingly, the function of the first optical element 80 as a collimator can be improved.

The second optical element 20 performs a function of transferring virtual video image light transmitted from the first optical element 80 to the third optical element 50 .

The second optical element 20 is buried inside the optical means 10 . That is, the second optical element 20 is spaced apart from the first surface 11, the second surface 12, the third surface 13, and the fourth surface 14 of the optical means 10, respectively, and the optical means ( 10) is placed in the inner space.

The second optical element 20 may include a plurality of optical modules arranged in a matrix form when viewed from the front, as shown in FIGS. 7 to 9 , in order to widen the viewing angle. In this specification, the second optical element 20 is collectively referred to as a plurality of optical modules.

The second optical element 20 is preferably a reflection means for reflecting and emitting incident virtual video image light. For example, the second optical element 20 may be formed of a material having a high reflectance of 100% or close to 100%, such as a metal material.

In the optical device 300 of FIGS. 7 to 9 , as described above, the virtual video image light emitted from the first optical element 80 is totally reflected by the second surface 12 of the optical means 10, and then 2 is transmitted to the optical element 20.

Accordingly, the plurality of optical modules constituting the second optical element 20 transmit the virtual video image light incident along the optical path to the third optical element 50 so that the first surface ( 11) and the second surface 12 to have an appropriate inclination angle.

As described above, each of the plurality of optical modules constituting the second optical element 20 has a size smaller than the size of a human pupil, that is, 8 mm or less, to obtain a pinhole effect by deepening the depth of field. Preferably, it is preferable to form it to 4 mm or less.

As a result, the depth of field for the light incident to the pupil 40 via the third optical element 50 by the optical modules can be made almost infinite, that is, the depth of field can be made very deep. Even if the focal length of the real world is changed while gazing at the real world, a pinhole effect may be generated, in which the focus of the virtual image is always recognized as correct regardless of this.

Here, the size of each optical module is defined as the maximum length between any two points on the edge boundary line of each optical module.

In addition, the size of each optical module is between any two points on the edge boundary line of the orthographic projection of each optical module on a plane perpendicular to the straight line between the pupil 40 and the optical module and including the center of the pupil 40. can be of maximum length.

However, since a diffraction phenomenon increases when the size of the optical modules is too small, the size of the optical modules is preferably larger than at least 0.3 mm.

Also, each of the optical modules may have a circular shape.

In addition, the optical modules may be formed in an elliptical shape so that the optical modules appear circular when viewed from the pupil 40 .

Meanwhile, each of the plurality of optical modules is preferably arranged so that the virtual video image light transmitted from the first optical element 80 is not blocked by other optical modules. The plurality of optical modules are arranged in a line on a vertical line when viewing the optical device 300 from the side, as shown in FIG. .

In addition, as shown in FIG. 8, the second optical element 20 may be arranged in a matrix form in which the height of each column is sequentially staggered when viewed from the front, but this is also exemplary, and the height of each column Of course, it may be arranged in other forms, such as making all the same or making only some columns the same height.

Meanwhile, the second optical element 20 may be configured with a means such as a half mirror that partially reflects and partially transmits light.

In addition, the second optical element 20 may be formed of any one of a refractive optical element, a diffractive optical element (DOE), and a holographic optical element (HOE).

In addition, the second optical element 20 may be formed of an optical element such as a notch filter that selectively transmits light according to a wavelength.

In addition, the second optical element 20 may be composed of a polarization filter that polarizes and emits light.

Next, the third optical element 50 will be described.

The third optical element 50 performs a function of providing a virtual image to the user by transferring the virtual image image light transmitted from the second optical element 20 toward the pupil 40 of the user's eye. In addition, the third optical element 50 functions to transmit real object image light emitted from objects in the real world to the pupil 40 of the user's eye through the first surface 11 of the optical means 10. also perform

The third optical element 50 is arranged in the optical means 10 between the second optical element 20 and the pupil 40 . 7 to 9, the third optical element 50 is disposed on the inner surface of the first surface 11 of the optical means 10, but this is exemplary, and the first surface of the optical means 10 ( 11), of course, may be disposed on the outer surface. In addition, it may be disposed spaced apart from the inner surface of the first surface 11 of the optical means 10.

Also, the third optical element 50 may be disposed between the second optical element 20 and the second surface 12 of the optical means 10 .

In the embodiments of FIGS. 7 to 9 , the third optical element 50 is shown as being formed in a rectangular planar shape when viewed from the front, but this is exemplary and may be formed in other shapes such as circular, elliptical, etc. am.

Also, the third optical element 50 may be formed in a single plane. Therefore, as shown in FIG. 9, the form factor of the optical means 10 and the optical device 300 can be kept small because they occupy little space in the left-right direction (z-axis direction) of the optical means 10 when viewed from the side. can

Meanwhile, in the present invention, the third optical element 50 is characterized in that it is a negative refractive optical element.

The negative refractive optical element refers to an optical element that refracts incident light in a direction symmetrical with respect to a general refractive direction of light having a positive refractive index and a normal line of an emission surface.

Here, the general direction of refraction of light means a direction of refraction according to Snell's law.

Referring to FIG. 10 , incident light L _i is incident from a medium 1 having a refractive index n ₁ to a medium ₂ having a refractive index n 2 . Incident light (L _i ) has an angle of θ ₁ with respect to the normal (z) of the exit surface (x).

At this time, according to Snell's law, the light (L ₁ ) emitted from the emission surface (x) having a refractive direction having a general positive refractive index has an angle of θ _2p with respect to the normal (z) of the emission surface (x). .

On the other hand, the light (L ₂ ) is refracted at an angle of θ _2n with respect to the normal (z) of the emission surface (x), which is symmetrical to the light (L ₁ ) with respect to the normal (z) of the emission surface (x). am. That is, θ _2p and θ _2n form an angle having the same magnitude and opposite directions around the normal (z).

In this way, the phenomenon of refracting the incident light (L _i ) in a direction symmetrical to the general refractive direction of light having a positive refractive index and the normal of the exit surface is called a negative refraction phenomenon, and an optical element that generates such a negative refraction phenomenon is a negative refraction phenomenon. It is called a refractive optical element.

According to Snell's law, this can be expressed as:

(

)

(

)

Here, when the refractive index ratio (n ₂ /n ₁ ) of medium 2 and medium 1 is n, the above formula can be expressed as follows.

(

)

(

)

Here, n when smaller than 0 can be defined as a negative refractive constant.

Such a negatively refractive optical element may be formed of a metamaterial having a negative refractive index in a specific wavelength band. Also, the negative refractive optical element may be formed with an array of micromirrors.

In addition, FIG. 10 shows the negative refraction phenomenon according to the difference in refractive index of the medium along the x-axis to show the principle of negative refraction, but this is exemplary and the negative refraction element has its own negative refraction regardless of the refractive index of the surrounding medium. Since it may have a constant, incident light may be emitted in a negative direction according to a negative refractive constant.

In the present invention, since the horizontal direction when the user looks at the optical means 10, that is, the negative refraction phenomenon in the x-axis direction in FIGS. 7 to 9 is used, the incident light L _i is only in the x-axis direction. A negative refractive optical element exhibiting negative refraction is used.

Comparing FIG. 11 with FIG. 6 , FIG. 11 is the same as FIG. 6 , except that a third optical element 50 is additionally disposed.

As shown in FIG. 11, since the third optical element 50, which is a negative refractive optical element, is disposed, the virtual video image light entering the third optical element 50 is negatively refractive in the x-axis direction as described above. Due to the phenomenon, it is refracted in a direction symmetrical to the direction having a positive refractive index in the x-z plane. Accordingly, an eyebox area as shown in FIG. 11 can be obtained.

In FIG. 11 , the entire eyebox area of the x-z plane of the optical device 300 is a hatched area, and the length of the eyebox in the horizontal direction (x-axis direction) is d2. Here, the length d2 of the eyebox in the horizontal direction can be expressed by the following formula.

d2 = d1-2ABS(y1-y2)tan(FOV/2)

Here, d1 is the length of the first optical element 80, and FOV represents the viewing angle. In addition, y1 is the distance from the first optical element 80 to the exit pupil, that is, the second optical element 20, and y2 is the distance from the second optical element 20 to the pupil 40, that is, , eye relief. Also, ABS represents an absolute value symbol.

Comparing these formulas with the formulas described in FIGS. 5 and 6, in the case of FIG. 11 using negative refractive optical elements for the same length d1 of the first optical element 80, the horizontal eyebox length d2 ) can be made larger.

In addition, in order to obtain a desired length d2 of the eyebox in the horizontal direction, it means that a shorter first optical element 80 can be employed than the case of FIG. 6 in which a negatively refractive optical element is not used.

In this case, the horizontal length d1 of the first optical element 80 can be calculated by the following formula.

d1 = d2 + 2ABS(y1-y2)tan(FOV/2)

Therefore, by using such a negative refractive optical element as the third optical element 50, there is an advantage in that the length of the first optical element 80 can be reduced while maintaining the same eye box area. In addition, when the same length of the first optical element 80 is maintained, a wider eyebox area can be obtained by using a negatively refractive optical element.

Accordingly, since the horizontal eyebox and field of view (FOV) of the optical device 300 may be increased, the overall form factor of the optical device 300 may be remarkably reduced.

As shown in FIG. 12, it can be seen that the incident light L _i is emitted at different angles according to the negative refractive constant n.

Here, n is the negative refractive constant as described above, and when n is less than -1, the angle of refraction (θ ₂ ) is smaller than the angle of incidence (θ ₁ ), and when n is -1, the angle of refraction (θ ₂ ) is It has the same magnitude as the angle of incidence (θ ₁ ). In addition, when n is greater than -1 and less than 0, the angle of refraction (θ ₂ ) is greater than the angle of incidence (θ ₁ ).

13 shows a case where the negative refractive constant is n=-1, and the viewing angle (FOV, θ ₂ ) in the eyebox at this time is the viewing angle (θ ₁ ) between the image output unit 30 and the first optical element 80 Same as

Meanwhile, FIG. 14 shows a case where the negative refractive constant is -1<n<0, and the angle of view (FOV, θ ₂ ) in the eyebox at this time is the angle of view between the image output unit 30 and the first optical element 80. greater than (θ ₁ ).

As such, according to the optical device 300 of the present invention, it can be seen that a wider field of view (FOV) can be obtained by adjusting the negative refractive constant.

The optical device 400 of FIG. 15 is the same as the optical device 300 of FIGS. 7 to 9 , but shows a case in which the diffraction element 60 is used as the second optical element 20 .

Here, the diffractive element means an optical element that refracts or reflects incident virtual video image light through a diffraction phenomenon. That is, the diffractive element may be referred to as an optical element that provides various optical functions by using a diffraction phenomenon of light.

The diffractive element has advantages in that a point-to-point image without aberration and a planar structure are possible, and aberration control such as an aspherical surface is possible. In addition, although the diffractive element has a very thin thickness of several μm, it is advantageous to reduce the volume and weight of the optical system because it plays a role similar to a general lens, prism, or mirror having a thickness of several mm.

In particular, the diffractive element operates as a refracting or reflecting element only for light that matches the design wavelength band of the nanostructure due to the wavelength-dependent characteristics of the diffraction phenomenon, and is a window that simply passes light in other wavelength bands. play a role Therefore, by using such a diffractive element, the transparency is increased to secure more brightness of the perspective image, and since the optical synthesizer structure is not observed from the outside, an optical device for augmented reality with better aesthetics similar to general glasses is provided. There are advantages to being able to do it.

Such a diffraction element can be divided into a reflection-type diffraction element and a transmission-type diffraction element. The optical device 400 of FIG. 15 is a case in which a transmissive diffractive element is used.

A reflective diffraction element refers to a diffraction element using a property of reflecting light incident from a specific direction and position, and a transmission type diffraction element refers to a diffraction element using a property of transmitting light incident from a specific direction and position. means small.

Basic configurations and characteristics of these diffraction elements, reflection-type diffraction elements, and transmission-type diffraction elements themselves are known in the prior art, and thus detailed descriptions thereof are omitted here.

On the other hand, the diffractive element 60 is preferably formed in a rectangular planar shape when viewed from the front, but this is exemplary, and may be formed in other shapes such as circular, elliptical, etc., of course. Also, the diffractive element 60 may be formed in a curved surface.

Also, the diffraction element 60 is formed in a single plane. Therefore, it has the advantage of being able to uniform the luminance distribution of the virtual image, and since it takes up almost no space in the left and right directions of the optical means 10 when viewed from the side, the form factor of the optical device 400 can be remarkably reduced. there is.

The size of the diffractive element 60 is an exit pupil required by various conditions such as the size and viewing angle of the virtual image transmitted to the pupil 40 by the diffractive element 60 and the third optical element 50. It can be formed as one single flat or curved surface with a size corresponding to the area. Considering this point, the diffractive element 60 may be formed to have a larger size than the pupil 40 when viewed from the front.

In addition, as described above, since the diffraction element 60 transmits real object image light emitted from objects in the real world to the pupil 40 of the user's eye through the third optical element 50, the pupil Even when formed as a single plane having a size greater than (40), real object image light may pass through the diffraction element 60 and be transmitted to the pupil 40.

Meanwhile, in the embodiment of FIG. 15 , a holographic optical element (HOE) may be used instead of the diffraction element 60 .

Since other configurations are the same as those of the previously described embodiment, detailed descriptions are omitted.

The embodiment of FIG. 16 is an optical element in which the diffractive element 60 as described in FIG. 15 and the third optical element 50, which is a negative refractive optical element described with reference to FIGS. 7 to 15, are formed as a single structure, This is referred to as the second optical element 70 in FIG. 16 .

That is, the second optical element 70 in FIG. 16 transmits the virtual video image light emitted from the image emitting unit 30 and transmitted through the first optical element 80 to the pupil 40 of the user's eye. A diffractive element that transmits real object image light emitted from objects in the real world to the pupil 40 of the user's eye, wherein the direction of refraction of light having a positive refractive index and the direction symmetrical with respect to the normal of the emission surface It can be referred to as a negative refraction diffraction element that refracts virtual video image light.

In this way, by using the diffractive element 60 and the second optical element 70 having the characteristics of the negative refractive optical element, the luminance distribution of the virtual image can be made more uniform while the form factor can be more remarkably reduced. have

Since other components are the same as those described with reference to FIGS. 7 to 15 , detailed descriptions thereof will be omitted.

Although the present invention has been described above with reference to preferred embodiments of the present invention, the present invention is not limited to the above embodiments, and various other modifications and variations are possible, of course.

Claims

A compact augmented reality optical device using a built-in collimator and a negative refractive optical element,

a first optical element that converts the virtual image image light emitted from the image emitter into collimated collimated light and transmits it to a second optical element;

a second optical element that transmits the virtual video image light transmitted from the first optical element to a third optical element;

A virtual image is provided to the user by passing the virtual image image light transmitted from the second optical element toward the pupil of the user's eye, and the real object image light emitted from the object in the real world is transmitted through the pupil of the user's eye. a third optical element that transmits; and

An optical means in which the first optical element, the second optical element, and the third optical element are disposed, and transmits real object image light emitted from a real object toward the pupil of the user's eye.

including,

The optical device for augmented reality according to claim 1 , wherein the third optical element is a negatively refractive optical element that refracts virtual video image light in a direction symmetrical to a refractive direction of light having a positive refractive index and a normal line of an emission surface.
The method of claim 1,

The virtual video image light emitted from the image emitting unit is directly transmitted to the first optical element through the inside of the optical means, or is transmitted to the first optical element after being totally reflected at least once on an inner surface of the optical means. An optical device for augmented reality, characterized in that.
The method of claim 1,

Characterized in that the virtual video image light converted into collimated parallel light by the first optical element is directly transmitted to the second optical element or transmitted to the second optical element after being totally reflected at least once on the inner surface of the optical means. Optical devices for augmented reality.
The method of claim 1,

The optical means includes a first surface through which virtual video image light and real object image light transmitted through the third optical element are emitted toward the user's pupil, and a first surface opposite to the first surface through which real object image light is incident. has two sides,

The first optical element is a reflection means for reflecting and radiating incident virtual video image light, and the reflecting surface of the first optical element is disposed to face the first surface or the second surface of the optical means. optical devices for augmented reality.
The method of claim 4,

The optical device for augmented reality, characterized in that the reflective surface of the first optical element is a curved surface formed concavely.
The method of claim 1,

The optical device for augmented reality according to claim 1 , wherein the first optical element extends closer to the image output unit from the central portion toward both left and right ends when the optical means is viewed from the pupil toward the front direction.
The method of claim 1,

The optical device for augmented reality, characterized in that the second optical element is buried inside the optical means.
The method of claim 1,

The optical device for augmented reality, characterized in that the second optical element is composed of a plurality of optical modules arranged in a matrix form when viewed from the front.
The method of claim 1,

The optical device for augmented reality, characterized in that the second optical element is a reflection means for reflecting and emitting incident virtual video image light.
The method of claim 1,

The optical device for augmented reality, characterized in that the third optical element refracts virtual video image light in a horizontal direction when a user looks at the optical means.
The method of claim 1,

The optical device for augmented reality, characterized in that the third optical element is disposed in the optical means between the second optical element and the pupil of the user's eye.
The method of claim 1,

The optical means includes a first surface through which virtual video image light and real object image light transmitted through the third optical element are emitted toward the user's pupil, and a first surface opposite to the first surface through which real object image light is incident. has two sides,

wherein the third optical element is disposed on an inner surface or an outer surface of the first surface of the optical means, or disposed between the second optical element and the second surface of the optical means. .
The method of claim 1,

When the length of the eyebox in the horizontal direction observed in the pupil of the user's eye is d2, the length of the first optical element in the horizontal direction (d1) is d1 = d2 + 2ABS(y1-y2)tan(FOV/2 For augmented reality, characterized in that calculated by the formula of (here, FOV is the viewing angle, y1 is the distance from the first optical element to the second optical element, y2 is the distance from the second optical element to the pupil) optical device.
The method of claim 1,

The optical device for augmented reality, characterized in that the second optical element is a diffractive element.
The method of claim 14,

The optical device for augmented reality, characterized in that the second optical element is a reflection type diffraction element or a transmission type diffraction element.
The method of claim 14,

The optical device for augmented reality, characterized in that the second optical element is a holographic optical element (HOE).
The method of claim 14,

The optical device for augmented reality, characterized in that the second optical element is a diffractive element formed in a single plane.
As an optical device for compact augmented reality using a negative refraction optical element,

a first optical element that converts the virtual image image light emitted from the image emitter into collimated collimated light and transmits it to a second optical element;

a second optical element that transmits the virtual image image light transmitted from the first optical element to the pupil of the user's eye and transmits real object image light emitted from objects in the real world to the pupil of the user's eye; and

An optical means in which the first optical element and the second optical element are disposed, and transmits real object image light emitted from a real object toward the pupil of the user's eye.

including,

The optical device for augmented reality according to claim 1 , wherein the second optical element is a negative refraction diffraction element that refracts virtual video image light in a direction symmetrical to a refractive direction of light having a positive refractive index and a normal line of an emission surface.