CN113219660A

CN113219660A - Projection optical machine for AR glasses

Info

Publication number: CN113219660A
Application number: CN202110400596.4A
Authority: CN
Inventors: 聂红星; 邓杨春; 丁卫涛
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2021-04-14
Filing date: 2021-04-14
Publication date: 2021-08-06
Also published as: WO2022217943A1

Abstract

The invention discloses a projection optical machine for AR glasses, which is arranged along the same optical axis sequence from an image surface to an object surface and comprises: a diaphragm; a first lens which is a positive power lens; a second lens which is a negative power lens; a third lens which is a positive power lens; a fourth lens, a positive power lens; and the light source unit comprises a red light unit, a green light unit and a blue light unit. According to the invention, a plurality of lenses are used, red, blue and green three-color light-emitting panels are carried, and then projection is carried out through the lenses, so that full-color display is realized, and the volume can reach 1 cubic centimeter; the imaging quality of the projection light machine meets the requirement of resolution ratio.

Description

Projection optical machine for AR glasses

Technical Field

The invention relates to the technical field of projection, in particular to a projection optical machine for AR glasses.

Background

Currently, the display screen mainly matched with the existing ar (amplified reality) glasses based on the diffractive light waveguide scheme is lcos (liquid Crystal on silicon) or Micro LED. The optical machine of the AR glasses adopting the diffractive optical waveguide scheme has the following problems:

the DLP or LCOS display screen system has a large volume generally larger than 4 cubic centimeters and a complex structure, so that the thinning of AR glasses cannot be realized; the system adopting the Micro LED display screen has the advantages that the Micro LED is self-luminous, the system can save the part of an illumination light path compared with DLP and LCOS schemes, the structure is compact, the size is small, however, due to the limitation of the process and the light effect, the AR (augmented reality) bare engine matched with the Micro LED display screen at present is more in a monochromatic light system, and the use scene of the AR bare engine matched with the Micro LED display screen is also limited.

In summary, it is desirable to design a projection optics for AR glasses to solve the above-mentioned problems in the prior art.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a projection optical machine for AR glasses, which uses a diffraction optical waveguide, carries R, G, B three-color Micro LED panels, and then projects through a lens, so that the volume of the projection optical machine can reach 1 cubic centimeter while full-color display is realized. In order to achieve the purpose, the invention adopts the following technical scheme:

a projection light machine for AR glasses comprises the following components in sequence from an image surface to an object surface along the same optical axis:

a diaphragm;

a first lens which is a positive power lens;

a second lens which is a negative power lens;

a third lens which is a positive power lens;

a fourth lens which is a positive power lens;

and the light source unit comprises a red light unit, a green light unit and a blue light unit.

In some embodiments of the invention, the light projector further comprises a prism located between the light source unit and the fourth lens.

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

In some embodiments of the present invention, the red light unit and the blue light unit are a red-blue combined light emitting panel; the green light unit is an independent green light panel; the prism is a double-cemented prism; the double-cemented prism is formed by cementing two triangular prisms.

In some embodiments of the present invention, the red light unit, the green light unit, and the blue light unit are a red-blue-green combined light emitting panel.

In some embodiments of the invention, the focal length f of the first lens is₁And a focal length f of the third lens₃The following relation is satisfied: 1<f₁/f₃<10; focal length f of the second lens₂And a focal length f of the fourth lens₄The following relation is satisfied: -10<f₂/f₄<-0.1。

In some embodiments of the invention, the thickness C of the first lens₁And a thickness C of the second lens₂The following relation is satisfied: 1<C₁/C₂<5; thickness C of the third lens₃And a thickness C of the fourth lens₄The following relation is satisfied: 0.5<C₃/C₄<5。

In some embodiments of the present invention, the focal length f of the projection optics and the length a of the projection optics satisfy the following relation: 0.1<f/A<3; a distance A between the third lens and the fourth lens₃The length A of the projection light machine satisfies the following relational expression: 0<A₃/A<1。

In some embodiments of the invention, the abbe number Vd of the second lens is larger than the abbe number Vd of the first lens₂The ranges of (A) are: vd₂Less than or equal to 30; abbe number Vd of the fourth lens₄The ranges of (A) are: vd₄≥50。

In some embodiments of the present invention, a side of the first lens facing the object plane is a convex surface, and a side facing the image plane is a concave surface; the side of the second lens, which faces the object plane, is a concave surface, and the side of the second lens, which faces the image plane, is a concave surface; one side of the third lens, which faces the image plane, is a convex surface; one side of the fourth lens, which faces the object plane, is a convex surface.

In some embodiments of the present invention, the light source unit employs a Micro LED panel.

In some embodiments of the present invention, the second lens and the third lens are cemented lenses; the gluing surface is bent towards the diaphragm.

Compared with the prior art, the technical scheme of the invention has the following technical effects:

according to the invention, a plurality of lenses are used, red, blue and green three-color light-emitting panels are carried, and then projection is carried out through the lenses, so that full-color display is realized, and the volume can reach 1 cubic centimeter; the imaging quality of the projection light machine meets the requirement of resolution ratio.

In addition, the prism is used for color combination of the monochromatic light, so that the loss of a monochromatic light source is avoided; and meanwhile, parameters of each lens in the projection optical machine and the spacing position between the lenses are limited, so that the chromatic aberration of the system can be effectively controlled.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a first structural diagram of the optical projection engine.

Fig. 2 is a schematic structural diagram of the projection optical machine.

Fig. 3 is a third schematic structural diagram of the optical projection engine.

Fig. 4 is a fourth schematic structural diagram of the optical projection engine.

Fig. 5 is a fifth structural diagram of the optical projection engine.

Fig. 6 is a first transfer function diagram of the optical system of the projection optical machine.

Fig. 7 is a second transfer function diagram of the optical system of the projection optical machine.

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

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected unless otherwise explicitly stated or limited. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In the foregoing description of embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

Example 1

Referring to fig. 1, a projection optical machine for AR glasses includes, in order from an image plane to an object plane along a same optical axis: a diaphragm 9; a first lens 1 which is a positive power lens; a second lens 2 which is a negative power lens; a third lens 3 which is a positive power lens; a fourth lens 4 which is a positive power lens; a light source unit; which 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 the light-emitting panels can be exchanged; the light source unit adopts a Micro LED panel, namely a red light unit adopts a red panel 61, a green light unit adopts a green panel 62, and a blue light unit adopts a blue panel 63.

In this embodiment, a prism 5 is further included, and the prism 5 is a four-cemented prism, as shown in fig. 1 and 2, specifically, four triangular prisms are cemented together, so that the light sources of the individual monochromatic light-emitting panels can be combined. Specifically, the right-angle edges of four identical right-angle prisms are glued, and after being incident from the hypotenuses of three of the right-angle prisms, each monochromatic light emitting panel is emergent from the hypotenuse of the fourth right-angle prism after passing through each gluing surface.

In this embodimentFocal length f of said first lens 1₁And a focal length f of the third lens 3₃The following relation is satisfied: 1<f₁/f₃<10; focal length f of the second lens 2₂And a focal length f of the fourth lens 4₄The following relation is satisfied: -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; the focal length of the fourth lens 4 is: 6.5.

thickness C of the first lens 1₁And a thickness C of the second lens 2₂The following relation is satisfied: 1<C₁/C₂<5; thickness C of the third lens 3₃And a thickness C of the fourth lens 4₄The following relation is satisfied: 0.5<C₃/C₄<5。

The focal length f of the projection light machine and the length A of the projection light machine satisfy the following relational expression: 0.1< f/A < 3; specifically, the focal length f of the projection light engine is: 6.6; the length A of the projection light machine is as follows: 14.5.

a distance A between the first lens 1 and the second lens 2₁And the interval A between the second lens and the third lens 3₂The following relation is satisfied: 0.1<A₁/A₂(ii) a A distance A between the third lens 3 and the fourth lens 4₃The length A of the projection light machine satisfies the following relational expression: 0<A₃/A<1. In particular, the interval A₁Comprises the following steps: 1.3; said interval A₂Comprises the following steps: 0.3; said interval A₃Comprises the following steps: 0.1.

an Abbe number Vd of the second lens 2₂The ranges of (A) are: vd₂Less than or equal to 30; an Abbe number Vd of the fourth lens 4₄The ranges of (A) are: vd₄≥50。

The parameters of the respective lenses in this example are shown in table 1; in addition, L1 referred to in the respective tables in the embodiments 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 aspherical surface of each lens is defined by the following aspherical surface curve formula:

wherein

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

c: curvature of aspheric vertex;

k: the cone coefficient;

a radial distance;

r_nnormalizing the radius;

u：r/r_n；

A_m: order m

A coefficient;

order m

A polynomial;

the aspherical coefficients are shown in table 2 below.

TABLE 2

As shown in fig. 6, the MTF value of the optical system of this embodiment is closer to 1, which indicates that the performance of the projection optical machine is better, and as the spatial frequency increases, the MTF values decrease slowly in the tangential direction and the sagittal direction at different heights of the field of view, indicating that the contrast of the projection optical machine is high, the imaging quality is still high, and the imaging quality meets the requirement of resolution.

Example 2

In comparison with example 1, refer to fig. 2. The respective lens parameters of this example are shown with reference to table 3.

TABLE 3

The aspherical coefficients are shown in table 4.

TABLE 4

As shown in fig. 7, the MTF value of the optical system of this embodiment is closer to 1, which indicates that the performance of the projection optical system is more excellent; in a low-frequency area, under different field heights, the MTF values tend to 1 along the tangential direction and the sagittal direction, the contrast of the projection optical machine is high, and the imaging quality is good; along with the increase of the spatial frequency, under different field heights, the MTF values in the tangential direction and the sagittal direction slowly decrease, which indicates that the imaging quality of the projection optical machine is still high, and the imaging quality meets the requirement of resolution.

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, whereas in embodiment 1, the two planes of the fourth lens 4 are both convex. The other lens variations are specifically referenced to the respective parameter lists.

Example 3

In contrast to embodiment 1, referring to fig. 3, the red light unit and the blue light unit in this embodiment are a red-blue combined light emitting panel 64; the green light unit is a separate green light panel 62; the prism 5 is a double cemented prism formed by cementing two triangular prisms. 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 sides of two different right-angle prisms, and are emitted from one right-angle side close to the fourth lens 4 after color combination by the gluing surface.

Example 4

In contrast to embodiment 1, referring to fig. 4, the red light unit, the green light unit, and the blue light unit are a red-blue-green combined light emitting panel 65; the prism 5 can be omitted from the light engine.

Example 5

In comparison with embodiment 1, referring to fig. 5, the second lens 2 and the third lens 3 are cemented lenses, and the cemented surfaces are curved toward the stop 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; the focal length of the fourth lens 4 is: 7.73.

the respective lens parameters of this example are shown with reference to table 5.

TABLE 5

The aspherical coefficients are shown in table 6.

TABLE 6

In addition, the prism is used for color combination of the monochromatic light, so that the loss of a monochromatic light source is avoided; and meanwhile, parameters and setting positions of all lenses in the projection optical machine are limited, so that chromatic aberration of the system can be effectively controlled.

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

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A projection light machine for AR glasses is characterized in that the projection light machine sequentially comprises the following components from an image surface to an object surface along the same optical axis:

a diaphragm;

a first lens which is a positive power lens;

a second lens which is a negative power lens;

a third lens which is a positive power lens;

a fourth lens which is a positive power lens;

2. The light projector as claimed in claim 1, wherein the light projector further comprises a prism between the light source unit and the fourth lens.

3. The light projector as claimed in 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-cemented prism formed by four triangular prisms through cementing.

4. The light projector as claimed in claim 2, wherein the red light unit and the blue light unit are a red-blue combined light emitting panel; the green light unit is an independent green light panel; the prism is a double-cemented prism; the double-cemented prism is formed by cementing two triangular prisms.

5. The light projector as claimed in claim 1, wherein the red light unit, the green light unit and the blue light unit are a red-blue-green combined light emitting panel; the light source unit adopts a Micro LED panel.

6. The projection engine for AR glasses according to claim 1, wherein the focal length f of the first lens₁And a focal length f of the third lens₃The following relation is satisfied: 1<f₁/f₃<10; focal length f of the second lens₂And a focal length f of the fourth lens₄The following relation is satisfied: -10< f₂/f₄<-0.1。

7. The projection engine for AR glasses according to claim 1, wherein the thickness C of the first lens₁And a thickness C of the second lens₂The following relation is satisfied: 1<C₁/C₂<5; thickness C of the third lens₃And a thickness C of the fourth lens₄The following relation is satisfied: 0.5<C₃/C₄<5。

8. The projection engine for AR glasses according to claim 6, wherein the focal length f of the projection engine and the length a of the projection engine satisfy the following relation: 0.1<f/A<3; a distance A between the third lens and the fourth lens₃The length A of the projection light machine satisfies the following relational expression: 0< A₃/A<1。

9. The projection light engine for AR glasses according to claim 1, wherein said second lens has an Abbe number Vd₂The ranges of (A) are: vd₂Less than or equal to 30; abbe number Vd of the fourth lens₄The ranges of (A) are: vd₄≥50。

10. The optical projection engine for AR glasses according to claim 1, wherein the first lens is convex on the side facing the object plane and concave on the side facing the image plane; the side of the second lens, which faces the object plane, is a concave surface, and the side of the second lens, which faces the image plane, is a concave surface; one side of the third lens, which faces the image plane, is a convex surface; one side of the fourth lens, which faces the object plane, is a convex surface.

11. The projection light engine for AR glasses according to claim 1, wherein the second lens and the third lens are cemented lenses.