KR20220006023A - Compact optical device for augmented reality using embedded collimator and negative refractive optical element - Google Patents

Abstract

The present invention provides a compact optical apparatus for augmented reality using an embedded collimator and a negative refractive optical element, comprising: a first optical device converting virtual image light, emitted from an image output unit, into collimated parallel light to transmit the collimated parallel light to a second optical element; the second optical element transmitting the virtual image light, transmitted from the first optical element, to a third optical element; the third optical element providing the virtual image to a user by transmitting the virtual image light, transmitted from the second optical element, toward the pupil of the user's eye, and allowing real object image light, emitted from an object in the real world, to be penetrated therethrough and transmitted to the pupil of the user's eye; and an optical means in which the first optical element, the second optical element, and the third optical element are disposed, and which allows the real object image light, emitted from the object in the real world, to be penetrated therethrough and transmitted toward the pupil of the user's eye, wherein the third optical element is a negative refractive optical element which refracts the virtual image light in the refraction direction of light having a positive refractive index and in the direction of being symmetrical to the normal line of an exit surface. The present invention can reduce a form factor while increasing a field of view.

Description

COMPACT OPTICAL DEVICE FOR AUGMENTED REALITY USING EMBEDDED COLLIMATOR AND NEGATIVE REFRACTIVE OPTICAL ELEMENT

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

Augmented reality (AR, Augmented Reality) is, as is well known, by providing a virtual image provided by a computer or the like on top of a real image of the real world, augmented (augmented) virtual image information from visual information of the real world. It means technology that is simultaneously provided to users.

An apparatus for implementing such augmented reality requires an optical combiner that allows a virtual image to be simultaneously observed with a real image 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 problems in that the transmittance of the virtual image is low and the volume and weight increase to provide a wide viewing angle, so it is difficult to provide a comfortable fit. 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 semi-mirrors are disposed inside a waveguide has been proposed, but these technologies also allow the image light of a virtual image inside the waveguide to be a semi-mirror. The manufacturing process is complicated because it has to pass through several times, and there is a limit that the light uniformity may be lowered due to manufacturing errors.

In addition, the holographic/diffraction optical device method generally uses a nano-structured grating or a diffraction grating, which has limitations in that the manufacturing cost is high and the yield for mass production is low because they are manufactured by a very precise process. In addition, due to a difference in diffraction efficiency according to a wavelength band and an incident angle, color uniformity and image sharpness are low. Holographic/diffractive optical elements are often used with waveguides such as the LOE described above, and thus still have the same problem.

In addition, conventional optical synthesizers have a limitation in that a virtual image becomes 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 a focal length for a virtual image or a variable focal lens capable of electrically controlling a focal length has been proposed. However, this technique also has a problem in that a user needs to perform a separate operation to adjust the focal length, or separate hardware and software for controlling the focal length are required.

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

1 is a diagram illustrating 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 means 10 , a reflection unit 20 , and an image output unit 30 .

The optical means 10 transmits the real object image light, which is image light emitted from the object in the real world, to the pupil 40 , while emitting the virtual image image light reflected by the reflection unit 20 to the pupil 40 . It is a means of performing A reflection unit 20 is embedded in the optical means 10 .

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

The reflection unit 20 reflects the virtual image image light emitted from the image output unit 30 and transmits it toward the user's pupil 40 .

The reflector 20 of FIG. 1 is formed to have a size smaller than the human pupil. Since the size of the human pupil is known to be about 4 to 8 mm, the reflective unit 20 is preferably formed to have a size of 8 mm or less, more preferably 4 mm or less. Accordingly, the Depth of Field for the light incident to the pupil 40 through the reflector 20 can be made close to infinity, that is, very deep.

Here, the depth of field refers to a range recognized as being in focus. As the depth increases, the range of the focal length for the virtual image also expands correspondingly. Therefore, even if the user changes the focal length for the real world while gazing at the real world, the virtual image is always recognized as in focus regardless of the change. This can be seen as a kind of pinhole effect.

Accordingly, by forming the reflector 20 to be smaller 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 document 2).

2 to 4 are views showing an optical device 200 for augmented reality based on the technology as disclosed in Prior Art Document 2, in which 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. 1 , but the reflector 20 includes a plurality of reflections to widen the viewing angle and the eye box. 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 disposed inside the optical means 10 to output from the image output unit 30 . There is a difference in that the virtual image image light is transmitted to the reflection modules 21 to 29 by the collimator 80 .

By disposing the collimator 80 inside the optical means 10 in this way, the optical apparatus 200 for augmented reality of FIGS. 2 to 4 does not need to include a collimator in the image output unit 30 unlike FIG. 1 . No, the image output unit 30 may be configured only with a micro display device.

In the optical device 200 for augmented reality of FIGS. 2 to 4 , the virtual image image light emitted from the image output unit 30 is totally reflected from the inner surface of the optical means 10 and then transmitted to the collimator 80 , and the collimator 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 are incident virtual image images. 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, the built-in collimator 80 is used inside the optical means 10 without using a collimator for the image output unit 30 . It has the advantage of being able to reduce the overall size, thickness, weight and volume of the device.

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

5 and 6 are views for explaining a horizontal eye box of the optical device 200 for augmented reality, and FIG. 5 is a plan view of the optical device 200 for augmented reality, and FIG. 6 is equivalent to FIG. It shows the optical system.

5 and 6 , the virtual image image light emitted from the three points A, B, and C to the image output unit 30 is transmitted to the pupil 40 through the collimator 80 and the reflector 20 . and areas where they overlap are indicated by hatching. The overlapping area indicated by the hatching corresponds to the maximum eyebox area in the x-z plane.

At this time, the length of the eye box 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. to be.

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

This means that the length of the collimator 80 needs to be increased in order to widen the eye box in the horizontal direction in the optical device 200 for augmented reality. However, as the length of the collimator 80 increases, there is a problem in that the design becomes more complicated and the manufacturing process also becomes complicated. In addition, as the length of the collimator 80 increases, the probability of generating a ghost image increases and the probability of blocking the actual object image light also increases. In addition, the aesthetics are not good because it stands out in appearance. Therefore, it is necessary to minimize the length of the collimator 80 as much as possible.

Korean Patent Publication No. 10-2018-0028339 (published on March 16, 2018) Republic of Korea Patent Publication No. 10-2200144 (Notice on Aug. 8, 2021)

The present invention is intended to solve the above problems, and by using a built-in collimator and a negative refractive optical element, an eyebox and a field of view (FOV) can be widened while reducing a form factor. Optics for compact augmented reality The purpose is 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, and can minimize the occurrence of ghost images and increase the transmission efficiency of real object image light. Another object of the present invention is to provide an optical device for augmented reality.

In order to solve the above problems, the present invention provides an optical device for compact augmented reality using a negative refractive optical element, which converts virtual image image light emitted from an image output unit into collimated collimated light into a second optical element. a first optical element that transmits; a second optical element transmitting the virtual image image light transmitted from the first optical element to a third optical element; The virtual image image light transmitted from the second optical element is transmitted toward the pupil of the user's eye to provide a virtual image to the user, and the real object image light emitted from the object in the real world is transmitted to the pupil of the user's eye. a third optical element that transmits; and optical means in which the first optical element, the second optical element, and the third optical element are disposed, and transmits the real object image light emitted from the real object toward the pupil of the user's eye, wherein the third The optical element provides an optical device for augmented reality, characterized in that it is a negative refractive optical element that refracts virtual image image light in a direction symmetrical with respect to the normal line of the emitting surface and the refraction direction of light having a positive refractive index.

Here, the virtual image image light emitted from the image output unit is transmitted directly 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 transmitted to

In addition, the virtual image image light converted into collimated collimated light in the first optical element may be transmitted directly to the second optical element or may be totally reflected at least once on the inner surface of the optical means and then transferred to the second optical element. .

In addition, the optical means includes a first surface through which the virtual image 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 opposite the first surface and the real object image light is incident wherein the first optical element is a reflective means for reflecting and emitting incident virtual image image light, and the reflective surface of the first optical element reflects the first surface or the second surface of the optical means. It can be arranged to face.

In addition, 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 the left and right ends from the central portion when the optical means is viewed from the pupil in the front direction.

In addition, the second optical element may be disposed to be embedded in the optical means.

In addition, 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 the incident virtual image image light and emitting it.

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

In addition, 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 image 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 opposite 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 disposed between the second optical element and the second surface of the optical means. .

In addition, when the length of the eye box in the horizontal direction observed from 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).

In addition, the second optical element may be a diffractive element.

In addition, the second optical element may be a reflective diffractive element or a transmissive diffractive element.

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

In addition, the second optical element may be a diffractive element formed in a single plane.

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

According to the present invention, it is possible to provide an optical device for 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 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, and can minimize the occurrence of ghost images and increase the transmission efficiency of real object image light. It is possible to provide an optical device for augmented reality.

1 is a diagram illustrating an optical device 100 for augmented reality as described in Prior Art Document 1 .
2 to 4 are views showing an optical device 200 for augmented reality based on the technology as disclosed in Prior Art Document 2, in which Fig. 2 is a side view, Fig. 3 is a perspective view, and Fig. 4 is a front view.
5 and 6 are views for explaining a horizontal eye box of the optical device 200 for augmented reality, and FIG. 5 is a plan view of the optical device 200 for augmented reality, and FIG. 6 is equivalent to FIG. It shows the optical system.
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 view for explaining the principle of a negative refractive optical element.
11 is a diagram for explaining an eye box of the optical device 300 and shows an equivalent optical system with respect to a plan view of the optical device 300 .
12 shows the negative refraction phenomenon according to the negative refractive constant.
13 and 14 are diagrams for explaining a change in a viewing angle according to a negative refractive constant.
15 is a side view of an optical device 400 according to another embodiment of the present invention.
16 is 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 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;

7 to 9, the optical device 300 for compact augmented reality using the built-in collimator and negative refractive optical element of this embodiment (hereinafter simply referred to as "optical device 300") is 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 transmits the real object image light emitted from the real world object to the pupil 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 image 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 the actual object image light is incident.

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

The image output unit 30 is a means for displaying a virtual image and emitting a virtual image light that is an 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 embedded in the optical means 10 as will be described later, the image output unit 30 is a small LCD, OLED, LCoS, micro LED It may be implemented with a conventionally known micro display device, such as.

Here, the virtual image means an image for augmented reality, and may be an image or a moving picture. 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 image image light emitted from the image output unit 30 is totally reflected by the second surface 12 of the optical means 10 to the first optical element 80 . Although shown to be transmitted, this is exemplary and may be directly transmitted 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 total reflection from the inner surface of the optical means 10 may be transmitted to the first optical element 80 twice or more.

In addition, in FIGS. 7 to 9 , the image output unit 30 is shown as being disposed above the upper surface of the optical means 10 , ie, 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 to be spaced apart from the third surface 13 of the optical means 10 , but this is exemplary and may be disposed to be in contact with the third surface 13 . Of course it could be.

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

The first optical element 80 may be implemented as a reflection unit that reflects incident virtual image image light and emits collimated parallel light. For example, the first optical element 80 may be formed of a material having a high reflectance of 100% or almost 100%, such as a metal material.

The first optical element 80 is disposed to be embedded in the optical means 10 so as to face the image output unit 30 as shown in FIGS. 7 to 9 .

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

Accordingly, the first optical element 80 emits the virtual image image light which is totally reflected and incident on the second surface 12 of the optical means 10 toward the second surface 12 of the optical means 10 and optically The image output unit 30 , the second optical element 20 , and the third optical so that the augmented reality image light totally reflected by the second surface 12 of the means 10 can be transmitted to the second optical element 20 . In consideration of 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 surface 11 and the second surface 12 of the optical means 10 .

To this end, in the embodiment of FIGS. 7 to 9 , in the first optical element 80 , the reflective surface 81 of the first optical element 80 that reflects the virtual image image light is the second of the optical means 10 . It is disposed embedded in the interior of the optical means (10) to face the surface (12).

Here, a straight line in a vertical direction from the center of the reflective 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, the first optical element 80 emits the virtual image image light toward the second surface 12 , while the stray light that is emitted from the real object and can generate a ghost image is emitted from the pupil 40 . It has the advantage of being able to block transmission to the other side.

However, this is an example, and the reflective surface 81 of the first optical element 80 may be disposed embedded in the optical means 10 so that the reflective surface 81 of the optical means 10 faces 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 reflective 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 embedded in the optical means 10 and can serve as a built-in collimator for collimating the virtual image image light emitted from the image output unit 30 , and thus There is no need to use a configuration such as a collimator for the image output unit 30 .

In addition, in order to prevent the user from recognizing the first optical element 80 as much as possible, it is preferable that the thickness of the first optical element 80 is thin when the user looks at the front through the pupil 40 .

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

In addition, the first optical element 80 may be formed of a refractive element or a diffractive element other than the reflecting means, or a combination of at least one of them.

Also, 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, the opposite surface of the reflective surface 81 that reflects the virtual image image light of the first optical element 80 may be coated with a material that does not reflect light but absorbs light.

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 first optical element 80 has an image output unit 30 from the center toward both ends on the left and right. ) may be formed to extend closer to the That is, when viewed from the front, the first optical element 80 may be formed in a generally smooth "U"-shaped bar shape. Accordingly, the function of the first optical element 80 as a collimator may be improved.

The second optical element 20 transmits the virtual image image light transmitted from the first optical element 80 to the third optical element 50 .

The second optical element 20 is disposed embedded in 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 interior space.

The second optical element 20 may be composed of 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 the entire plurality of optical modules.

It is preferable that the second optical element 20 is a reflecting means for reflecting the incident virtual image image light and emitting it. 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 image 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 may transmit the virtual image image light incident along the optical path to the third optical element 50 on the first surface ( 11) and the second surface 12 is disposed 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 human pupil size, that is, 8 mm or less, so as to obtain a pinhole effect by increasing the depth of field. Preferably, it is preferable to form 4 mm or less.

Thereby, the depth of field for light incident to the pupil 40 through the third optical element 50 by the optical modules can be made close to infinity, that is, the depth can be very deep. Even if the focal length for the real world is changed while gazing at the real world, a pinhole effect may occur that makes the virtual image always be in focus regardless of the change.

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

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

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

Also, the shape of each of the optical modules may be circular.

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 image 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 the optical device 300 is viewed from the side as shown in FIG. 9, but this is exemplary and may be arranged in an oblique or other gentle curved shape. .

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

Meanwhile, the second optical element 20 may be configured as 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 element (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.

Also, the second optical element 20 may be configured as a polarization filter that polarizes and emits light.

Next, the third optical element 50 will be described.

The third optical element 50 provides a virtual image to the user by transmitting 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 transmits the real object image light emitted from the object in the real world to the pupil 40 of the user's eye through the first surface 11 of the optical means 10 . also do

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) may be disposed on the outer surface of course. In addition, it may be disposed to be spaced apart from the inner surface of the first surface 11 of the optical means 10 .

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

7 to 9, the third optical element 50 is shown to be formed in a rectangular planar shape when viewed from the front, but this is exemplary and may be formed in other shapes such as a circle, an oval, etc. to be.

Also, the third optical element 50 may be formed in a single plane. Accordingly, the form factors of the optical means 10 and the optical device 300 are kept small since they hardly occupy space in the left-right direction (z-axis direction) of the optical means 10 when viewed from the side as shown in FIG. 9 . 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 to a normal refraction direction of light having a positive refractive index and a normal line of an exit surface.

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

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

Referring to FIG. 10 , the incident light L _i is incident from the medium 1 having the refractive index n ₁ to the medium 2 having the refractive index n ₂ . The 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, light (L ₁ ) emitted from the exit surface (x) with a refraction direction having a general positive refractive index has an angle of _{θ 2p} with respect to the normal line (z) of the exit surface (x) .

On the other hand, light (L _{2 ) has an angle of θ 2n} with respect to the normal (z) of the _{exit surface (x) and is refracted and emitted, which is symmetric with the light (L 1} ) with respect to the normal (z) of the exit surface (x). to be. That is, θ _2p and θ _2n are the same in magnitude and form opposite angles with respect to the normal (z).

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

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

(

)

(

)

(

)

(

)

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

(

)

(

)

(

)

(

)

Here, n when less than 0 may be defined as a negative refractive constant.

Such a negative refractive optical element may be formed of a meta material having a negative refractive index in a specific wavelength band. Also, the negative refractive optical element may be formed as an array of micromirrors.

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

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

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

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

11, since the third optical element 50, which is a negative refractive optical element, is disposed, the virtual image image light incident on 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 a direction having a positive refractive index in the xz plane. Accordingly, an eye box area as shown in FIG. 11 can be obtained.

In FIG. 11 , the entire eye box area in the x-z plane of the optical device 300 is an area indicated by hatching, and the eye box length in the horizontal direction (x-axis direction) is d2. Here, the length d2 of the eye box in the horizontal direction may be expressed by the following equation.

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, , is eye relief. Also, ABS represents an absolute value symbol.

Comparing this equation with the equations described with reference to FIGS. 5 and 6 , in the case of FIG. 11 using a negative refractive optical element with respect to the length d1 of the same first optical element 80 , the length d2 of the eye box in the horizontal direction ) can be made larger.

In addition, it means that the first optical element 80 having a smaller length can be adopted compared to the case of FIG. 6 in which the negative refractive optical element is not used in order to obtain the desired length d2 of the eye box in the horizontal direction.

In this case, the length d1 in the horizontal direction of the first optical element 80 may be calculated by the following equation.

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

Accordingly, by using the 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, there is an advantage that a wider eye box area can be obtained by using a negative refractive optical element.

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

12 shows the negative refraction phenomenon according to the negative refraction constant.

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 a negative refractive constant, as described above, n is less than -1 refraction angle (θ ₂₎ is an incident angle is smaller than the size (θ _1), when n is -1 refraction angle (θ ₂₎ is It has the same magnitude as the incident angle (θ _{1 ).} In addition, when n is greater than -1 and less than 0, the refraction angle θ ₂ is greater than the incident angle θ _{1 .}

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

13 is a case in which the negative refraction constant n = -1. In this case, the viewing angle (FOV, θ _{2 ) in the eye box is the viewing angle (θ 1} ) between the image output unit 30 and the first optical element 80 . same as

On the other hand, FIG. 14 shows a case where the negative refractive constant -1<n<0. In this case, the viewing angle FOV,θ ₂ in the eye box is the viewing angle between the image output unit 30 and the first optical element 80 . greater than (θ _{1 ).}

As described above, 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.

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

The optical device 400 of FIG. 15 is the same as the optical device 300 of FIGS. 7 to 9 , except that the diffractive element 60 is used as the second optical element 20 .

Here, the diffractive element refers to an optical element that refracts or reflects incident virtual image image light through a diffraction phenomenon. That is, the diffraction element can be called an optical element that provides various optical functions by using the diffraction phenomenon of light.

The diffractive element has the advantage of being able to have a point-to-point image without aberration and a planar structure, and to control aberrations such as an aspherical surface. In addition, although the diffraction element has a very thin thickness of several μm, it is advantageous in reducing the volume and weight of the optical system because it functions similarly to a general lens, prism, or mirror having a thickness of several mm.

In particular, due to the wavelength-dependent nature of the diffraction phenomenon, the diffraction element operates as a refracting or reflective element only for light that matches the design wavelength band of the nanostructure, and a window that simply passes light in other wavelength bands. plays a role Therefore, by using such a diffractive element, transparency is increased to secure more brightness of a fluoroscopic image, and since the optical synthesizer structure is not observed from the outside, the appearance of the product is similar to ordinary glasses and provides an optical device for augmented reality with better esthetics There are advantages to being able to

Such a diffractive element may be divided into a reflective diffractive element and a transmissive diffractive element. The optical device 400 of FIG. 15 is a case in which a transmissive diffractive element is used.

The reflective diffraction element refers to a diffractive element that reflects light incident from a specific direction and position, and the transmissive diffractive element refers to a diffraction element that uses a property to transmit light incident from a specific direction and position. means small.

Since the basic configuration and characteristics of such a diffractive element, a reflective diffractive element, and a transmissive diffractive element are known in the prior art, a detailed description thereof will be omitted.

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 a circular shape, an oval shape, and the like. In addition, the diffractive element 60 may be formed in a curved surface.

Further, the diffractive element 60 is formed in a single plane. Accordingly, it has the advantage that the luminance distribution of the virtual image can be uniform, and the form factor of the optical device 400 can be significantly reduced because it takes up little space in the left and right directions of the optical means 10 when viewed from the side. have.

The size of the diffractive element 60 is an exit pupil required by various conditions such as the size and viewing angle of a virtual image transmitted to the pupil 40 by the diffractive element 60 and the third optical element 50 . It can be formed as a single flat or curved surface having a size corresponding to the area. Considering this point, the diffraction 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 the real object image light emitted from the object in the real world to the pupil 40 of the user's eye through the third optical element 50 , the pupil Even if it is formed as a single plane having a size larger than (40), the actual 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 diffractive element 60 .

Since other configurations are the same as those of the above-described embodiment, a detailed description thereof will be omitted.

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

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 into a single structure, This will be referred to as a second optical element 70 in FIG. 16 .

That is, the second optical element 70 in FIG. 16 transmits the virtual image image light emitted from the image output unit 30 and transmitted through the first optical element 80 to the pupil 40 of the user's eye. and a diffractive element that transmits the real object image light emitted from the real world object and transmits it to the pupil 40 of the user's eye. It can be said that it is a sound diffractive element that refracts virtual image 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 more uniform and the form factor can be more remarkably reduced. have

Since other configurations 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 with reference to the preferred embodiment of the present invention above, the present invention is not limited to the above embodiment, and of course, other various modifications and variations are possible.

100, 200...Conventional optics for augmented reality
300, 400, 500...Optical device for compact augmented reality with built-in collimator and negative refractive optical element
10...optical means
20...second optical element
30...image exit
40...pupil
50...third optical element
60...diffraction element
70...Sonic diffractive element
80...first optical element

Claims (18)

An optical device for compact augmented reality using a built-in collimator and a negative refractive optical element, comprising:
a first optical element that converts the virtual image image light emitted from the image output unit into collimated parallel light and transmits it to the second optical element;
a second optical element transmitting the virtual image image light transmitted from the first optical element to a third optical element;
The virtual image image light transmitted from the second optical element is transmitted toward the pupil of the user's eye to provide a virtual image to the user, and the real object image light emitted from the object in the real world is transmitted to the pupil of the user's eye. a third optical element that transmits; and
The first optical element, the second optical element, and the third optical element are disposed, and optical means for transmitting the real object image light emitted from the real object toward the pupil of the user's eye
including,
The third optical element is an optical device for augmented reality, characterized in that it is a negative refractive optical element that refracts the virtual image image light in a direction symmetrical to a refraction direction of light having a positive refractive index and a normal line of the exit surface. The method according to claim 1,
The virtual image image light emitted from the image output unit is transmitted directly 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 transmitted to the first optical element Optical device for augmented reality, characterized in that. The method according to claim 1,
The virtual image image light converted into collimated collimated light by the first optical element is transmitted directly to the second optical element or is totally reflected at least once on the inner surface of the optical means and then transmitted to the second optical element Optics for augmented reality. The method according to claim 1,
The optical means includes a first surface through which the virtual image image light and the real object image light transmitted through the third optical element are emitted toward the user's pupil, and a second surface opposite the first surface and onto which the real object image light is incident. has two sides,
The first optical element is a reflective means that reflects and emits incident virtual image image light, and the reflective surface of the first optical element is disposed to face the first or second surface of the optical means. optics for augmented reality. 5. The method according to claim 4,
The reflective surface of the first optical element is an optical device for augmented reality, characterized in that it is a concave curved surface. The method according to claim 1,
The first optical element is an optical device for augmented reality, characterized in that when the optical means is viewed from the pupil in the front direction, the optical device for augmented reality, characterized in that it is formed to extend closer to the image output portion toward the left and right ends from the central portion. The method according to claim 1,
The second optical element is an optical device for augmented reality, characterized in that it is embedded in the optical means. The method according to claim 1,
The second optical element is an optical device for augmented reality, characterized in that it is composed of a plurality of optical modules arranged in a matrix form when viewed from the front. The method according to claim 1,
The second optical element is an optical device for augmented reality, characterized in that it is a reflecting means for reflecting the incident virtual image image light and emitting it. The method according to claim 1,
The third optical element is an optical device for augmented reality, characterized in that when a user looks at the optical means, the virtual image image light is refracted in a horizontal direction. The method according to claim 1,
The third optical element is an optical device for augmented reality, characterized in that it is disposed in the optical means between the second optical element and the pupil of the user's eye. The method according to claim 1,
The optical means includes a first surface through which the virtual image image light and the real object image light transmitted through the third optical element are emitted toward the user's pupil, and a second surface opposite the first surface and onto which the real object image light is incident. has two sides,
The third optical element is disposed on the inner surface or the outer surface of the first surface of the optical means, or is disposed between the second optical element and the second surface of the optical means. . The method according to claim 1,
When the length of the eye box in the horizontal direction observed from 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). optical device. The method according to claim 1,
The second optical element is an optical device for augmented reality, characterized in that it is a diffractive element. 15. The method of claim 14,
The second optical element is an optical device for augmented reality, characterized in that it is a reflective diffractive element or a transmissive diffractive element. 15. The method of claim 14,
The second optical element is an optical device for augmented reality, characterized in that it is a holographic optical element (HOE). 15. The method of claim 14,
The second optical element is an optical device for augmented reality, characterized in that it is a diffractive element formed in a single plane. An optical device for compact augmented reality using a negative refractive optical element, comprising:
a first optical element that converts the virtual image image light emitted from the image output unit into collimated parallel light and transmits it to the 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 the real object image light emitted from the object 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 the real object image light emitted from the real object toward the pupil of the user's eye
including,
The second optical element is an optical device for augmented reality, characterized in that it is a negative diffraction element that refracts the virtual image image light in a direction symmetrical with respect to a refraction direction of light having a positive refractive index and a normal line of the emission surface.

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