WO2022227539A1

WO2022227539A1 - Optical module and head-mounted display device

Info

Publication number: WO2022227539A1
Application number: PCT/CN2021/133187
Authority: WO
Inventors: 史柴源; 胡惠惠; 张扬
Original assignee: 歌尔股份有限公司
Priority date: 2021-04-30
Filing date: 2021-11-25
Publication date: 2022-11-03
Also published as: CN113219666A

Abstract

An optical module and a head-mounted display device. The optical module comprises: a display (10) and a lens array (30); the display (10) is provided with a light-emitting surface for emitting light; the lens array (30) comprises a plurality of lenses; the plurality of lenses are arranged on the light-emitting surface of the display (10); the light transmits the lens array (30); and the lenses converge the light emitted by the display (10). The optical module can reduce the emergent angle of light emitted by the display (10), and effectively improve the luminous efficiency utilization rate of an edge view field.

Description

Optical Modules and Head Mounted Displays

technical field

The present invention relates to the technical field of optical display, in particular to an optical module and a head-mounted display device.

Background technique

Head mounted display (Head mounted display) device is an electronic product that can provide immersive experience. At present, the display principle of head mounted display device includes virtual reality (VR, Virtual Reality) technology, augmented reality (AR, Augmented Reality) technology and mixed reality (MR, Mixed Reality) technology.

A display is set inside the head-mounted display device, and the light-emitting angle of the display is fixed. As displays get smaller and smaller, the field of view of head-mounted display devices is getting larger and larger. In this way, the angle between the edge field of view and the display plane becomes larger and larger, and the light efficiency utilization rate of the edge gradually decreases.

SUMMARY OF THE INVENTION

Based on this, in view of the problem that the angle between the edge field of view and the display plane in the existing head-mounted display device is increasing, and the light efficiency utilization rate of the edge is gradually decreasing, it is necessary to provide an optical module and a head-mounted display device. , which aims to improve the light efficiency utilization of the edge field of view.

In order to achieve the above purpose, an optical module proposed by the present invention, the optical module includes:

a display having a light exit surface that emits light; and

A lens array, the lens array includes a plurality of lenses, and the lenses are arranged on the light emitting surface of the display, light transmits the lens array, and the lenses condense the light emitted by the display.

Optionally, the lens is disposed on a surface of the substrate facing away from the display, and the lens protrudes toward the side facing away from the display.

Optionally, the plurality of lenses include a first lens and a second lens, the first lens is arranged at the center of the light-emitting surface of the display, and the second lens is arranged at the edge of the light-emitting surface of the display;

The first lens has a convex first arc surface away from the display, the second lens has a second arc surface convex away from the display, and the radian of the first arc surface is defined as rad1, and the The radian of the second arc surface is rad2, then it satisfies: rad1<rad2.

Optionally, several of the lenses further include a third lens, and the third lens is provided between the first lens and the second lens;

The third lens has a third arc surface that protrudes away from the display, and the radian of the third arc surface is defined as rad3, then: rad1<rad3<rad2.

Optionally, the lens array further includes a substrate, the substrate is disposed on the light emitting surface of the display, and a plurality of the lenses are arranged on a surface of the substrate facing away from the display.

Optionally, the optical module includes an optical lens group, the optical lens group is arranged in the optical path of the side of the lens array away from the display, and the optical lens group includes a first lens and a semi-reflective and semi-transparent film. , the first lens comprises a first surface facing the display and a second surface facing away from the display, and the transflective film is arranged on the first surface;

The optical lens group further includes a quarter wave plate and a polarized reflection film, the quarter wave plate and the polarized reflection film are arranged on the side of the first mirror away from the display, and the four The half-wave plate and the polarized reflection film are arranged in sequence along the propagation direction of the light.

Optionally, the optical lens group includes a second lens, the second lens is disposed on a side of the first lens away from the display, the second lens includes a third surface facing the display and a back To the fourth surface of the display, the polarizing reflective film is provided on the third surface of the second mirror, and the quarter-wave plate is provided on the side of the polarizing reflective film facing the display.

Optionally, the optical lens group further includes a polarizing film, and the polarizing film is provided between the display and the polarizing reflection film.

Optionally, the optical lens group further includes a third lens, the third lens is disposed between the first lens and the second mirror, the third lens has a fifth surface facing the display and a sixth surface facing away from the display;

At least one of the first surface, the second surface, the fourth surface, the fifth surface and the sixth surface is an aspherical surface.

Optionally, the optical lens group further includes an anti-reflection film, and the anti-reflection film is provided on the fifth surface and/or the sixth surface.

Optionally, the optical lens group has an aperture angle through which light passes, the display has an exit angle of emitted light, and the angle of the exit angle after being modulated by the lens array is equal to the angle of the aperture angle.

In addition, in order to achieve the above object, the present invention also provides a head-mounted display device, the head-mounted display device includes a casing and the optical module as described above, and the optical module is provided in the casing.

In the technical solution proposed by the present invention, the light emitted by the display is directed towards the lens array. When the light passes through the lens array, the arranged lenses adjust the angle of the exit angle of the light, so that the light is converged, so that the angle of the exit angle becomes smaller. The outgoing light on the edge field of view of the display is fully utilized to avoid wasting light, thereby improving the light efficiency utilization rate of the edge field of view.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

1 is a schematic structural diagram of an optical module of the present invention;

FIG. 2 is a schematic structural diagram of the lens array in FIG. 1;

3 is a schematic structural diagram of a first lens and a second lens of the lens array in FIG. 1;

4 is a modulation transfer function diagram of an embodiment of the optical module of the present invention;

FIG. 5 is a dot diagram of an embodiment of an optical module of the present invention.

Description of reference numbers:

标号label	名称 name	标号label		名称name
1010	显示器 monitor	231231	第五表面 fifth surface
2020	光学镜组 Optical lens group	232232	第六表面 sixth surface
210210	第一镜片 first lens	3030	透镜阵列 lens array
211211	第一表面 first surface	310310	第一透镜 first lens
212212	第二表面 second surface	311311	第一弧面 first arc
220220	第二镜片 second lens	320320	第二透镜second lens

221221	第三表面 third surface	321321	第二弧面 second arc
222222	第四表面 fourth surface	330330	第三透镜 third lens
230230	第三镜片 third lens	340340	基板substrate

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relationship between various components under a certain posture (as shown in the accompanying drawings). The relative positional relationship, the movement situation, etc., if the specific posture changes, the directional indication also changes accordingly.

In addition, descriptions such as "first", "second", etc. in the present invention are only for descriptive purposes, and should not be construed as indicating or implying their relative importance or implicitly indicating the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

In the present invention, unless otherwise expressly specified and limited, the terms "connected", "fixed" and the like should be understood in a broad sense, for example, "fixed" may be a fixed connection, a detachable connection, or an integrated; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be an internal communication between two elements or an interaction relationship between the two elements, unless otherwise explicitly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

In the technical field of related head-mounted displays, a display is provided inside the head-mounted display device, and the light-emitting angle of the display is fixed. As displays get smaller and smaller, the field of view of head-mounted display devices is getting larger and larger. In this way, the angle between the edge field of view and the display plane becomes larger and larger, and the light efficiency utilization rate of the edge gradually decreases. Among them, the angle of the exit angle may be greater than the angle of the aperture angle, or the angle of the exit angle may be smaller than the angle of the aperture angle.

In order to solve the above problems, referring to FIG. 1 and FIG. 2 , this embodiment provides an optical module. The optical module includes a display 10 and a lens array 30 . The lens array 30 is arranged in the light-emitting direction of the display 10 . In this embodiment, the optical module can be used in a VR display device, and can also be used in an AR display device or an MR display device. The display 10 has a light-emitting surface that emits light; the light-emitting principle of the display 10 also includes a variety of, for example, liquid crystal display (LCD, Liquid Crystal Display), light emitting diode (LED, Light-emitting diode) and the like.

The lens array 30 includes a plurality of lenses arranged on the light emitting surface of the display 10 . The light passes through the lens array 30 , and the lens adjusts the angle of the exit angle of the light emitted by the display 10 , so that the lens converges the light emitted by the display. The main method of adjustment is to deflect the light, so that the light is refracted, thereby changing the propagation direction of the light.

In addition, the lens array 30 may be made of optical glass material or may be made of plastic material. Optical glass has good optical properties such as better reflectivity and transmittance. The plastic material is easy to process, which is convenient to quickly complete the processing of the lens array 30 .

In the technical solution proposed in this embodiment, the light emitted by the display 10 is directed toward the lens array 30 . When the light passes through the lens array 30, the arranged lenses adjust the angle of the exit angle of the light, so that the light is converged, so that the angle of the exit angle becomes smaller. The light emitted from the edge field of view of the display 10 is fully utilized to avoid wasting light, thereby improving the light efficiency utilization rate of the edge field of view.

In the above embodiment, generally speaking, the angle of the exit angle of the light emitted by the display 10 is relatively large, which makes it difficult to effectively utilize the light emitted from the display 10 at the edge position. In order to more effectively ensure that the angle of the exit angle becomes smaller. The lens protrudes toward the side facing away from the display 10 . Convergence of light can be achieved through the convex arrangement of the lens. After the light emitted by the display 10 passes through the lens, the light converges toward the middle position. In this way, the angle of the outgoing angle of the light becomes smaller, and the utilization rate of the light is ensured.

Referring to FIG. 3 , the position where the light is difficult to be fully utilized is located at the edge of the angle of the exit angle, in order to further adjust the propagation direction of the light at the edge of the angle of the exit angle. The plurality of lenses include a first lens 310 and a second lens 320, the first lens 310 is arranged at the center of the light-emitting surface of the display 10, and the second lens 320 is arranged at the edge of the light-emitting surface of the display 10; the first lens 310 has a convex surface away from the display 10. The first arc surface 311 and the second lens 320 have a second arc surface 321 that protrudes away from the display 10, and the radian of the first arc surface 311 is defined as rad1, and the arc of the second arc surface 321 is rad2, so that: rad1 <rad2. It can be seen that the arc corresponding to the second arc surface 321 is larger, and the arc is more curved. In this way, when the light passes through the second arc surface 321, the deflection angle of the light is also larger, which further ensures that the light can obtain the effect of a larger deflection angle at the edge position of the angle of the exit angle.

In the above embodiment, the plurality of lenses further include a third lens 330, the third lens 330 is disposed between the first lens 310 and the second lens 320; the third lens 330 has a third arc surface that is convex away from the display 10, which defines The radian of the third arc surface is rad3, which satisfies: rad1<rad3<rad2. It can be seen that the deflection angle of the light has a gradient change from the inside to the outside, that is, the radian value corresponding to the arc surface shows an increasing trend, thereby ensuring that the light gradually converges to the center position. Certainly, several lenses may also include a fourth lens, and the radian of the fourth lens is located between the radian corresponding to the first arc surface 311 and the radian corresponding to the third arc surface. In order to smoothly complete the transition of the deflection of the light, more lenses with different radians may be arranged between the first lens 310 and the second lens 320 . Satisfying the first lens 310 to the second lens 320, the radian corresponding to the arc surface shows an increasing trend.

It should be pointed out that in this embodiment, several lenses can be understood as several micro-lens structures, which are arranged according to certain rules. For example, the micro-lens structures are arranged in rows and columns, or the micro-lens structures may be arranged in an annular manner with the center of the display 10 being a dot.

In an embodiment of the present application, the lens array 30 further includes a substrate 340 . The substrate 340 is disposed on the light-emitting surface of the display 10 , and a plurality of lenses are arranged on the surface of the substrate 340 facing away from the display. The substrate 340 and the lens are both made of transparent materials, and the substrate 340 and the lens may be integrally provided. The base plate 340 facilitates the overall mounting when the lens array 30 is mounted.

In the related art, the volume of the head-mounted display device is relatively large. In order to reduce the volume of the head-mounted display device, the optical module includes an optical lens group 20, and the optical lens group 20 is arranged in the optical path on the side of the lens array 30 away from the display 10, The optical lens group 20 includes a first lens 210 and a transflective film. The first lens 210 includes a first surface 211 facing the display 10 and a second surface 212 facing away from the display 10. The transflective film is provided on the first surface. 211; the optical lens group 20 further comprises a quarter-wave plate and a polarized reflection film, the quarter-wave plate and the polarized reflection film are arranged on the side of the first mirror 210 away from the display 10, the quarter-wave plate and the polarized reflection film The reflective films are arranged in sequence along the propagation direction of the light. The light emitted by the display 10 first passes through the transflective film, part of the light is reflected, and the other part is transmitted. The light transmitted through the transflective film passes through the first lens 210 . The light is directed to the quarter-wave plate, and the polarization state of the light is converted from circularly polarized light to linearly polarized light, and the linearly polarized light is directed to the polarized reflective film. At this time, the transmission direction of the linearly polarized light is different from the transmission direction of the polarized reflection film, and the linearly polarized light is reflected. The reflected linearly polarized light is directed towards the transflective film. Under the action of a quarter-wave plate, the linearly polarized light is converted into circularly polarized light. Under the action of the transflective film, transmission and reflection occur again. The direction of rotation of the reflected circularly polarized light is changed, and the reflected circularly polarized light is again directed towards the quarter-wave plate. At this time, the circularly polarized light is converted into linearly polarized light again. The light of the linearly polarized light is transmitted in the same direction as the polarized reflective film, and the light of the linearly polarized light is transmitted. It can be seen from this that the light is refracted and reflected, thereby reducing the volume of the head-mounted display device, which is convenient for the user to wear.

In the above embodiment, the optical lens group 20 includes a second lens 220, the second lens 220 is disposed on the side of the first lens 210 away from the display 10, and the second lens 220 includes a third surface 221 facing the display 10 and facing away from the display. On the fourth surface 222 of the 10 , the polarizing reflective film is provided on the third surface 221 of the second lens 220 , and the quarter-wave plate is provided on the side of the polarizing reflective film facing the display 10 . The quarter-wave plate and the polarizing reflective film are film-layer structures, and the quarter-wave plate and the polarizing reflective film of the film-layer structure are disposed on the surface of the second mirror 220 to further reduce the volume.

In the above embodiment, the optical lens group 20 further includes a polarizing film, and the polarizing film is arranged between the display 10 and the polarizing reflective film. When the light passes through the optical lens group 20, a small amount of light passes through the light in a different direction than the light transmission direction of the polarized reflective film. This part of the light is stray light, which affects the image quality. This part of the light can be effectively eliminated by setting the polarizing film. The light transmission direction of the polarizing film is the same as that of the polarized reflective film, so that stray light in different directions can be eliminated.

In the process of refraction, the light travels back and forth between the polarized reflective film and the transflective film, and part of the light is far away from the optical axis, so the optical path is different between the position near the optical axis and the position far away from the optical axis. As a result, it is easy to generate aberrations. In order to reduce the generation of aberrations, the optical lens group 20 further includes a third lens 230, the third lens 230 is disposed between the first lens 210 and the second lens, and the third lens 230 has a fifth surface 231 facing the display 10 and facing away from the display 10. The sixth surface 232 of the display 10; at least one of the first surface 211, the second surface 212, the fourth surface 222, the fifth surface 231 and the sixth surface 232 is aspherical. Through the design of the aspheric surface, the curvature radius of the lens surface changes gradually from the center position to the edge position. For example, gradually increase or gradually decrease. Through the gradual change of the radius of curvature, the focus position of the light at the edge position is adjusted, thereby reducing the generation of aberrations.

In the above embodiment, in order to improve the transmittance of light, the optical lens group 20 further includes an anti-reflection film, and the anti-reflection film is arranged on the fifth surface 231 and/or the sixth surface 232 . There are at least three ways of disposing the anti-reflection film. The first is that the anti-reflection film is disposed on the fifth surface 231 . In the second case, the anti-reflection coating is provided on the sixth surface 232 . The third case is that the anti-reflection coating is provided on both the fifth surface 231 and the sixth surface 232 . The anti-reflection film can improve the transmittance of light, and the anti-reflection film can be set by sticking or coating. When pasting the settings, it is simple and easy to complete. When the coating film is installed, the film layer can be made stronger, and the coating film can improve the compactness of the film layer and increase the wear resistance of the anti-reflection film.

4 is a modulation transfer function diagram of the optical module of the present invention, namely an MTF (Modulation Transfer Function) diagram. The MTF diagram is used to refer to the relationship between the modulation degree and the number of line pairs per millimeter in the image, and is used to evaluate the restoration of the details of the scene. Capability; the system transfer function of the optical module is greater than 0.6 in each field of view, and the resolution performance is good.

5 is a dot diagram of the optical module of the present invention; the dot diagram means that after many rays emitted from one point pass through the optical module, the intersection with the image plane is no longer concentrated at the same point due to aberration, and a A dispersion pattern scattered over a certain range is used to evaluate the imaging quality of the projection optical system. The smaller the root mean square radius value and the geometric radius value, the better the imaging quality. The arrangement order of areas 1 to 9 is from left to right and from top to bottom.

In an embodiment of the present application, the optical lens group 20 is arranged in the optical path of the light emitted from the display 10, and the angle of the aperture angle through which the light passes is formed between the display 10 and the optical lens group 20; The passing light can normally display the image at the position of the human eye. The size of the angle of the aperture angle of the optical lens group 20 is related to the distance between the optical lens group 20 and the display 10. If the distance between the optical lens group 20 and the display 10 is fixed, the angle of the aperture angle of the optical lens group 20 is fixed. . Referring to FIG. 3 , the exit angle of the display is α, which is converted into β after passing through the lens, and the angle β is equal to the aperture angle of the optical lens group 20 after being modulated by the lens array 30 .

In this embodiment, the light emitted by the display 10 is directed to the optical lens group 20, and the aperture through which the light can pass through the optical lens group 20 is fixed, and the aperture is also called numerical aperture. The angles of the opposite sides of the aperture from the center position of the display 10 are also fixed, and this angle is the angle of the aperture angle. The angle at which light is emitted from the display 10 is the angle of the emission angle. If the angle of the exit angle is not equal to the angle of the aperture angle, an included angle is generated between the angle of the exit angle and the angle of the aperture angle. The light travels between the two angles, and this part of the light is not fully utilized, and this part of the light is wasted. Through the setting of the lens array 30, when the light passes through the lens array 30, the lenses arranged on the surface of the substrate 340 adjust the angle of the exit angle of the light emitted from the display 10, so that the angle of the exit angle is equal to the angle of the aperture angle. The angle between the angle of the corner and the angle of the aperture angle is zero. The light emitted from the fringe field of view of the display 10 is fully utilized, thereby improving the light efficiency utilization rate of the fringe field of view.

The present invention also provides a head-mounted display device. The head-mounted display device includes a casing and an optical module as described above, and the optical module is arranged in the casing. The optical module can be arranged in the casing, or the optical module can be wrapped in a half-pack. Through the protection of the shell, it can also play the role of ash and waterproof.

For the specific implementation of the head-mounted display device, reference may be made to the embodiment of the optical module, which will not be repeated here.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Under the inventive concept of the present invention, the equivalent structure transformation made by the contents of the description and drawings of the present invention, or directly/indirectly applied to other All relevant technical fields are included in the scope of patent protection of the present invention.

Claims

An optical module, characterized in that the optical module comprises:

a display having a light exit surface that emits light; and

A lens array, the lens array includes a plurality of lenses, and the lenses are arranged on the light emitting surface of the display, light transmits the lens array, and the lenses condense the light emitted by the display.
The optical module of claim 1, wherein the lens protrudes toward a side away from the display.
2. The optical module of claim 2, wherein the plurality of lenses comprises a first lens and a second lens, the first lens is located at the center of the light-emitting surface of the display, and the second lens is located at the center of the light-emitting surface of the display. at the edge of the light-emitting surface of the display;

The first lens has a convex first arc surface away from the display, the second lens has a second arc surface convex away from the display, and the radian of the first arc surface is defined as rad1, and the The radian of the second arc surface is rad2, then it satisfies: rad1<rad2.
The optical module according to claim 3, wherein the plurality of lenses further comprises a third lens, and the third lens is disposed between the first lens and the second lens;

The third lens has a third arc surface that protrudes away from the display, and the radian of the third arc surface is defined as rad3, then: rad1<rad3<rad2.
The optical module as claimed in claim 1, wherein the lens array further comprises a substrate, the substrate is arranged on the light emitting surface of the display, and a plurality of the lenses are arranged on the side of the substrate facing away from the display. board.
The optical module according to any one of claims 1 to 5, wherein the optical module comprises an optical lens group, and the optical lens group is arranged on an optical path on the side of the lens array away from the display wherein, the optical lens group includes a first lens and a transflective film, the first lens includes a first surface facing the display and a second surface facing away from the display, the transflective film on the first surface;

The optical lens group further includes a quarter wave plate and a polarized reflection film, the quarter wave plate and the polarized reflection film are arranged on the side of the first mirror away from the display, and the four The half-wave plate and the polarized reflection film are arranged in sequence along the propagation direction of the light.
The optical module according to claim 6, wherein the optical lens group comprises a second lens, the second lens is disposed on a side of the first lens away from the display, and the second lens is comprising a third surface facing the display and a fourth surface facing away from the display, the polarizing reflective film is provided on the third surface of the second mirror, and the quarter wave plate is provided on the polarizing The reflective film faces the side of the display.
The optical module according to claim 7, wherein the optical lens group further comprises a polarizing film, and the polarizing film is arranged between the display and the polarizing reflection film.
The optical module according to claim 7, wherein the optical lens group further comprises a third lens, the third lens is arranged between the first lens and the second lens, the first lens Three lenses have a fifth surface facing the display and a sixth surface facing away from the display;

At least one of the first surface, the second surface, the fourth surface, the fifth surface and the sixth surface is an aspherical surface.
The optical module according to claim 9, wherein the optical lens group further comprises an anti-reflection film, and the anti-reflection film is disposed on the fifth surface and/or the sixth surface.
The optical module according to claim 6, wherein the optical lens group has an aperture angle through which light passes, the display has an exit angle through which light is emitted, and the exit angle is modulated by the lens array. The angle is equal to the angle of the aperture angle.
A head-mounted display device, characterized in that, the head-mounted display device comprises a casing and the optical module according to any one of claims 1 to 11, wherein the optical module is provided in the casing.