WO2022217943A1

WO2022217943A1 - Projection light engine for ar glasses

Info

Publication number: WO2022217943A1
Application number: PCT/CN2021/135204
Authority: WO
Inventors: 聂红星; 邓杨春; 丁卫涛
Original assignee: 歌尔股份有限公司
Priority date: 2021-04-14
Filing date: 2021-12-03
Publication date: 2022-10-20
Also published as: CN113219660A

Abstract

A projection light engine for AR glasses, the projection light engine comprising in sequence, from an image surface to an object surface along the same optical axis: a stop (9); a first lens (1), which is a lens having positive focal power; a second lens (2), which is a lens having negative focal power; a third lens (3), which is a lens having positive focal power; a fourth lens (4), which is a lens having positive focal power; and a light source unit, which comprises a red light unit, a green light unit, and a blue light unit. By means of using the plurality of lenses (1, 2, 3, 4) and being equipped with light-emitting panels (61, 63, 62) of red, blue and green colors, and by means of projection through the lenses, the projection light engine may have a volume of 1 cubic centimeter while achieving full-color display; and the imaging quality of the projection light engine meets resolution requirements.

Description

A projector for AR glasses

This application claims the priority of the Chinese patent application filed on April 14, 2021 with the application number 202110400596.4 and the application title is "a light projector for AR glasses", the entire contents of which are incorporated by reference in in this application.

technical field

The present application relates to the field of projection technology, and in particular, to a projector light machine for AR glasses.

Background technique

The current AR (Augmented Reality) glasses based on the diffractive optical waveguide scheme are mainly equipped with LCOS (Liquid Crystal on Silicon) or Micro LED display. However, the optical machine of AR glasses using the diffractive optical waveguide scheme has the following problems:

The system using DLP or LCOS display screen is large in size, generally larger than 4 cubic centimeters, and the structure is complex, so it is impossible to realize the thinning of AR glasses; the system using Micro LED display screen, due to the self-illumination of Micro LED, compared with DLP and LCOS solutions The part of the lighting light path can be omitted, and the structure will be relatively compact and small in size. However, due to the limitations of technology and light efficiency, most of the AR light machines equipped with Micro LED displays are monochromatic light systems, which also limits the use of Micro LEDs. The usage scenario of the AR light machine of the LED display.

To sum up, it is now necessary to design a light projector for AR glasses to solve the above problems in the prior art.

Application content

In order to solve the above-mentioned problems in the prior art, the present application provides a light projector for AR glasses, which uses a diffractive light guide, is equipped with R, G, and B three-color Micro LED panels, and is projected through a lens to achieve full color. The displayed volume can be 1 cubic centimeter at the same time. To achieve the above object, the application adopts the following technical solutions:

An optical projector for AR glasses, the sequence from the image plane to the object plane along the same optical axis includes:

aperture;

a first lens, which is a positive refractive power lens;

the second lens, which is a negative refractive power lens;

the third lens, which is a positive refractive power lens;

the fourth lens, which is a positive refractive power lens;

The light source unit includes a red light unit, a green light unit and a blue light unit.

In some embodiments of the present application, the light projector further includes a prism located between the light source unit and the fourth lens.

In some embodiments of the present application, the red light unit, the green light unit and the blue light unit are independent light-emitting panels; the prism is a four-glued prism; the four-glued prism is formed by gluing four triangular prisms.

In some embodiments of the present application, the red light unit and the blue light unit are red and blue light-emitting panels; the green light unit is an independent green light panel; the prism is a double glued prism; the double glued prism is two The block prisms are glued together.

In some embodiments of the present application, the red light unit, the green light unit and the blue light unit are red, blue and green combined light-emitting panels.

In some embodiments of the present application, the focal length f1 of the first lens and the focal length f3 of the third lens satisfy the following relationship: 1<f1/f3<10; the focal length f2 of the second lens and the The focal length f4 of the fourth lens satisfies the following relation: -10<f2/f4<-0.1.

In some embodiments of the present application, the thickness C1 of the first lens and the thickness C2 of the second lens satisfy the following relationship: 1<C1/C2<5; the thickness C3 of the third lens and the The thickness C4 of the fourth lens satisfies the following relation: 0.5<C3/C4<5.

In some embodiments of the present application, the focal length f of the optical projector and the length A of the optical projector satisfy the following relationship: 0.1<f/A<3; the third lens and the fourth lens The interval A3 of the lenses and the length A of the projector satisfy the following relationship: 0<A3/A<1.

In some embodiments of the present application, the range of the Abbe number Vd2 of the second lens is: Vd2≤30; the range of the Abbe number Vd4 of the fourth lens is: Vd4≥50.

In some embodiments of the present application, the first lens is convex on the side facing the object plane and concave on the side facing the image plane; the second lens is concave on the side facing the object plane and concave on the side facing the image plane The side of the third lens toward the image plane is convex; the side of the fourth lens toward the object plane is convex.

In some embodiments of the present application, the light source unit adopts a Micro LED panel.

In some embodiments of the present application, the second lens and the third lens are cemented lenses; the cemented surface is curved toward the diaphragm.

The technical solution of the present application has the following technical effects relative to the prior art:

In this application, by using multiple lenses, equipped with three-color light-emitting panels of red, blue and green, and then projecting through the lenses, the full-color display can be achieved at the same time, and the volume can reach 1 cubic centimeter; the imaging quality of the projector meets the resolution. requirements.

In addition, the use of prisms to combine the colors of monochromatic light avoids the loss of monochromatic light sources; at the same time, the parameters of each lens in the projector and the space between the lenses are limited, which can effectively control the chromatic aberration of the system.

Description of drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only It is a part of the drawings of the present application. For those of ordinary skill in the art, other drawings can also be obtained from the provided drawings without any creative effort.

FIG. 1 is a schematic diagram 1 of the structure of the projector.

FIG. 2 is a second structural schematic diagram of the projector.

FIG. 3 is a third structural schematic diagram of the projector.

FIG. 4 is a fourth schematic diagram of the structure of the projector.

FIG. 5 is a schematic diagram 5 of the structure of the projector.

FIG. 6 is a transfer function diagram 1 of the optical system of the projector.

FIG. 7 is a second diagram of the transfer function of the optical system of the projector.

Reference numerals: 1-first lens; 2-second lens; 3-third lens; 4-fourth lens; 5-prism; 61-red panel; 62-green panel; 63-blue panel; 64- Red and blue combined light-emitting panel; 65-red, green and blue combined light-emitting panel; 9- diaphragm.

Detailed ways

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

Example 1

Referring to FIG. 1 , an optical projector for AR glasses includes sequentially along the same optical axis from the image plane to the object plane: a diaphragm 9; a first lens 1, which is a positive refractive power lens; a second lens 2 , which is a negative refractive power lens; the third lens 3 is a positive refractive power lens; the fourth lens 4 is a positive refractive power lens; a light source unit; it includes a red light unit, a green light unit and a blue light unit. In this embodiment, the red light unit, the green light unit and the blue light unit are independent light-emitting panels; the positions of each light-emitting panel can be exchanged; the light source unit adopts a Micro LED panel, that is, the red light unit adopts a red panel 61, The green light unit uses the green panel 62 , and the blue light unit uses the blue panel 63 .

In this embodiment, a prism 5 is also included, and the prism 5 is a four-glued prism, as shown in FIG. 1 and FIG. 2 . Specifically, four triangular prisms are glued together, and the light sources of each monochromatic light-emitting panel can be synthesized. Specifically, the right-angle sides of four identical right-angle prisms are glued, and each monochromatic light-emitting panel is incident from the hypotenuse of the three right-angle prisms, and then exits from the hypotenuse of the fourth right-angle prism after passing through each glued surface.

In this embodiment, the focal length f1 of the first lens 1 and the focal length f3 of the third lens 3 satisfy the following relationship: 1<f1/f3<10; the focal length f2 of the second lens 2 and the The focal length f4 of the fourth lens 4 satisfies the following relation: -10<f2/f4<-0.1.

Specifically, the focal length of the first lens 1 is: 7.62; the focal length of the second lens 2 is: -2.52; the focal length of the third lens 3 is: 5.43; and the focal length of the fourth lens 4 is: 6.5.

The thickness C1 of the first lens 1 and the thickness C2 of the second lens 2 satisfy the following relationship: 1<C1/C2<5; the thickness C3 of the third lens 3 and the thickness of the fourth lens 4 C4 satisfies the following relation: 0.5<C3/C4<5.

The focal length f of the optical projector and the length A of the optical projector satisfy the following relationship: 0.1<f/A<3; specifically, the focal length f of the optical projector is: 6.6; the length A of the optical projector as: 14.5.

The interval A1 between the first lens 1 and the second lens 2 and the interval A2 between the second lens and the third lens 3 satisfy the following relationship: 0.1<A1/A2; the third lens 3 and The interval A3 of the fourth lens 4 and the length A of the projector satisfy the following relationship: 0<A3/A<1. Specifically, the interval A1 is: 1.3; the interval A2 is: 0.3; the interval A3 is: 0.1.

The range of the Abbe number Vd2 of the second lens 2 is: Vd2≤30; the range of the Abbe number Vd4 of the fourth lens 4 is: Vd4≥50.

The parameters of each lens in this embodiment are shown in Table 1; in addition, L1 involved in each table in the embodiment represents the first lens 1, L2 represents the second lens 2, L3 represents the third lens 3, and L4 represents the Fourth lens 4 .

Table 1

The aspheric surface of each lens is defined by the following aspheric curve formula:

in

z: the depth of the aspheric surface (the point on the aspheric surface that is y away from the optical axis, and the tangent plane tangent to the vertex on the optical axis of the aspheric surface, the vertical distance between the two);

c: curvature of aspheric vertex;

K: cone coefficient;

radial distance;

rn normalized radius;

u:r/rn;

Am: mth order

coefficient;

mth order

polynomial;

The aspheric coefficients are shown in Table 2 below.

Table 2

The transfer function diagram of the optical system of this embodiment is shown in Figure 6. The closer the MTF value is to 1, the better the performance of the projector. The MTF value in the sagittal direction and the sagittal direction decreases slowly, indicating that the contrast of the projector is high, the image quality is still high, and the image quality meets the resolution requirements.

Example 2

Compared with Example 1, it is shown with reference to FIG. 2 . The various lens parameters of this embodiment are shown in Table 3 with reference to.

table 3

The aspheric coefficients are shown in Table 4.

Table 4

The transfer function diagram of the optical system of this embodiment is shown in Fig. 7. The closer the MTF value is to 1, the better the performance of the projector is; The MTF value tends to 1, the contrast of the projector is high and the image quality is good; with the increase of the spatial frequency, the MTF value along the tangential direction and the sagittal direction decreases slowly at different field heights, indicating that the projector has The image quality is still very high, and the image quality meets the resolution requirements.

In this embodiment, the thickness of the first lens 1 is smaller than that of the first lens 1 in Embodiment 1. The two planes of the fourth lens 4 are convex and concave, respectively, while in Embodiment 1, the two planes of the fourth lens 4 are both convex. For the changes of other lenses, please refer to each parameter list.

Example 3

Compared with Embodiment 1, as shown in FIG. 3 , in this embodiment, the red light unit and the blue light unit are combined red and blue light-emitting panels 64 ; the green light unit is an independent green light panel 62 ; the prism 5 It is a double-glued prism, which is formed by gluing two triangular prisms together. Specifically, the hypotenuses of two identical right-angle prisms are glued, and the green light panel 62 and the red-blue combined light-emitting panel 64 are respectively incident from the adjacent right-angle edges of the two different right-angle prisms, and after the glued surfaces are combined with color, It is emitted from one of the right-angle sides close to the fourth lens 4 .

Example 4

Compared with Embodiment 1, as shown in FIG. 4 , the red light unit, the green light unit and the blue light unit are red, blue and green combined light-emitting panels 65; the prism 5 can be omitted in the projector.

Example 5

Compared with Embodiment 1, as shown in FIG. 5 , the second lens 2 and the third lens 3 are cemented lenses, and the cemented surface is curved toward the diaphragm 9 . Specifically, the focal length of the first lens 1 is: 14.91; the focal length of the second lens 2 is: -2.76; the focal length of the third lens 3 is: 4.75; and the focal length of the fourth lens 4 is: 7.73.

The various lens parameters of this embodiment are shown in Table 5 with reference to.

table 5

The aspheric coefficients are shown in Table 6.

Table 6

In addition, the prism is used to combine the colors of the monochromatic light, which avoids the loss of the monochromatic light source; at the same time, the parameters and setting positions of each lens in the projector are limited, which can effectively control the chromatic aberration of the system.

In the foregoing description of the embodiments, the particular features, structures, materials or characteristics may be combined in any suitable manner in any one or more of the embodiments or examples.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application shall be covered. within the scope of protection of this application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

An optical projector for AR glasses, characterized in that the sequence from the image plane to the object plane along the same optical axis includes:

aperture;

a first lens, which is a positive refractive power lens;

the second lens, which is a negative refractive power lens;

the third lens, which is a positive refractive power lens;

the fourth lens, which is a positive refractive power lens;

The light source unit includes a red light unit, a green light unit and a blue light unit.
The light projector for AR glasses according to claim 1, wherein the light projector further comprises a prism, and the prism is located between the light source unit and the fourth lens.
The light projector for AR glasses according to claim 2, wherein the red light unit, the green light unit and the blue light unit are independent light-emitting panels; the prism is a four glued prism, and the four The glued prism is formed by gluing four triangular prisms together.
The light projector for AR glasses according to claim 2, wherein the red light unit and the blue light unit are combined red and blue light-emitting panels; the green light unit is an independent green light panel; The prism is a double-glued prism; the double-glued prism is formed by gluing two triangular prisms.
The light projector for AR glasses according to claim 1, wherein the red light unit, the green light unit and the blue light unit are red, blue and green combined light-emitting panels; the light source unit adopts a Micro LED panel .
The light projector for AR glasses according to claim 1, wherein the focal length f1 of the first lens and the focal length f3 of the third lens satisfy the following relationship: 1<f1/f3< 10; The focal length f2 of the second lens and the focal length f4 of the fourth lens satisfy the following relationship: -10<f2/f4<-0.1.
The light projector for AR glasses according to claim 1, wherein the thickness C1 of the first lens and the thickness C2 of the second lens satisfy the following relationship: 1<C1/C2< 5. The thickness C3 of the third lens and the thickness C4 of the fourth lens satisfy the following relationship: 0.5<C3/C4<5.
The light projector for AR glasses according to claim 6, wherein the focal length of the light projector is f and the length A of the light projector satisfies the following relationship: 0.1<f/A <3; The interval A3 between the third lens and the fourth lens and the length A of the projector satisfy the following relationship: 0<A3/A<1.
The light projector for AR glasses according to claim 1, wherein the Abbe number Vd2 of the second lens is in the range of: Vd2≤30; the Abbe number Vd4 of the fourth lens The range is: Vd4≥50.
The projector for AR glasses according to claim 1, wherein the first lens is convex on the side facing the object plane, and the second lens is concave on the side facing the image plane; the second lens faces the object The side of the surface is concave, and the side facing the image plane is concave; the side facing the image plane of the third lens is convex; the side facing the object surface of the fourth lens is convex.
The light projector for AR glasses according to claim 1, wherein the second lens and the third lens are cemented lenses.