CN116149065B

CN116149065B - Optical module and wearable equipment

Info

Publication number: CN116149065B
Application number: CN202310443693.0A
Authority: CN
Inventors: 史柴源; 姜龙
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Optical Technology Co Ltd
Priority date: 2023-04-24
Filing date: 2023-04-24
Publication date: 2023-08-04
Anticipated expiration: 2043-04-24
Also published as: CN116149065A

Abstract

The embodiment of the application provides an optical module and wearable equipment; the optical module comprises an imaging lens group, a light splitting element, a first phase retarder and a polarization reflecting element, wherein the light splitting element, the first phase retarder and the polarization reflecting element are arranged between light paths of the imaging lens group, and the first phase retarder is positioned between the light splitting element and the polarization reflecting element; the optical module further comprises a display assembly, the display assembly comprises a first display screen and a second display screen, the first display screen and the second display screen are arranged in an up-down symmetrical mode relative to the optical axis of the imaging lens group, a target interval L is arranged between the first display screen and the second display screen, and the target interval L is more than or equal to 1.5mm. The optical module provided by the embodiment of the application is a single-eye double-screen VR scheme, and can achieve the optical effect of increasing the angle of view.

Description

Optical module and wearable equipment

Technical Field

The embodiment of the application relates to the technical field of optical imaging, and more particularly relates to an optical module and a wearable device.

Background

In recent years, virtual Reality (VR) technology has been applied and rapidly developed in, for example, wearable devices such as smart glasses, helmets, and the like. The core component of the virtual reality technology is a VR optical system, and the quality of the image effect of the VR optical system will directly determine the quality of the wearable device.

With the continuous improvement of consumption demands, the requirements on the size and imaging quality of virtual reality products are higher and higher, and miniaturization and high resolution are the development trend of future virtual reality display products. In fact, the smaller the size of the display of the VR product, the higher the resolution, the higher the requirements on the VR optical system, especially the field angle, but currently it is difficult to achieve a large field angle for a small size display.

Disclosure of Invention

The purpose of this application is to provide a new technical scheme of optical module and wearable equipment, has realized the effect of increase visual field angle through the optical scheme that the monocular corresponds two display screens.

In a first aspect, the present application provides an optical module. The optical module comprises an imaging lens group, a light splitting element, a first phase retarder and a polarization reflecting element, wherein the light splitting element, the first phase retarder and the polarization reflecting element are arranged between light paths of the imaging lens group, and the first phase retarder is positioned between the light splitting element and the polarization reflecting element;

the optical module further comprises a display assembly, the display assembly comprises a first display screen and a second display screen, the first display screen and the second display screen are arranged in an up-down symmetrical mode relative to the optical axis of the imaging lens group, a target interval L is arranged between the first display screen and the second display screen, and the target interval L is more than or equal to 1.5mm.

Optionally, when the display component displays an image, the first image displayed by the first display screen and the second image displayed by the second display screen have an overlapping area, and the overlapping area is close to the optical axis.

Optionally, the imaging lens group includes at least one lens, and the optical power of the at least one lens is positive.

Optionally, the imaging lens group includes a first lens and a second lens that are adjacent and arranged at intervals, and the focal powers of the first lens and the second lens are positive;

the first lens is positioned at one side close to the display assembly, and the second lens is positioned at one side far away from the display assembly;

the first lens comprises a first surface and a second surface, the first surface is close to the display assembly, the second surface is far away from the display assembly, and the first surface and the second surface are rotationally symmetrical about the optical axis.

Optionally, the first surface and the second surface form a target included angle θ, where the target included angle θ is: θ is more than 0 and less than or equal to 20 degrees.

Optionally, the light splitting element is disposed on a side of the second lens, which is close to the display component, and the first phase retarder and the polarization reflection element are sequentially disposed on a side of the second lens, which is far away from the display component.

Optionally, the light splitting element is disposed on a surface of the second lens, which is close to the display component;

the optical module further comprises a first polarizing element;

the first phase retarder, the polarized reflecting element and the first polarized element are sequentially stacked to form a composite film, and the composite film is arranged on the surface, far away from the display assembly, of the second lens.

Optionally, the imaging lens group further includes a third lens, the third lens is located between the first lens and the display component, the first lens, the second lens and the third lens are located on the same optical axis, and optical power of the third lens is positive.

Optionally, the optical power Φ1 of the first lens is: phi 1 is more than or equal to 0.01; the focal power phi 2 of the second lens is as follows: 0< phi 2<0.1; the focal power phi 3 of the third lens is: phi 3 is more than or equal to 0 and less than or equal to 0.1.

Optionally, the effective focal length EFL of the optical module is 20 mm-30 mm.

Optionally, the total length TTL of the optical system of the optical module is 15 mm-30 mm.

Optionally, the first display screen and the second display screen are configured to be capable of emitting circularly polarized light or natural light;

when the light rays emitted by the first display screen and the second display screen are natural light, overlapping elements are respectively arranged on the light emitting sides of the first display screen and the second display screen and used for converting the natural light into circularly polarized light; wherein the superposition element comprises at least a second phase retarder and a second polarizing element.

In a second aspect, the present application provides a wearable device comprising:

a housing; and

the optical module of the first aspect.

The beneficial effects of this application are:

according to the optical module provided by the embodiment of the application, the optical module is of a folding light path structure, and the optical scheme of the monocular corresponding double display screen is formed by introducing two display screens symmetrically arranged along the same optical axis in the optical module, so that the view field angle of the optical module can be increased, for example, 100-degree or even larger view field angle can be realized, and the visual experience of a user can be improved. The whole light path structure is simple in design, and the miniaturization and high-quality imaging of the optical module are realized.

Other features of the present specification and its advantages will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and together with the description, serve to explain the principles of the specification.

FIG. 1 is a schematic diagram of an optical module according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a composite film disposed on a surface of a second lens in an optical module according to an embodiment of the disclosure;

FIG. 3 is a graph of the MTF of the optical module shown in FIG. 1;

FIG. 4 is a point diagram of the optical module shown in FIG. 1;

FIG. 5 is a graph of field curvature distortion of the optical module shown in FIG. 1;

FIG. 6 is a vertical axis color difference plot of the optical module shown in FIG. 1;

FIG. 7 is a second schematic diagram of an optical module according to an embodiment of the disclosure;

FIG. 8 is a graph of the MTF of the optical module shown in FIG. 7;

FIG. 9 is a point diagram of the optical module shown in FIG. 7;

FIG. 10 is a graph of field curvature distortion of the optical module shown in FIG. 7;

fig. 11 is a vertical axis color difference diagram of the optical module shown in fig. 7.

Reference numerals illustrate:

1. a first display screen; 11. a first light-emitting surface; 2. a second display screen; 21. a second light-emitting surface; 3. a first lens; 31. a first surface; 32. a second surface; 4. a second lens; 41. a third surface; 42. a fourth surface; 5. a third lens; 51. a fifth surface; 52. a sixth surface; 6. a spectroscopic element; 7. a composite membrane; 71. a first phase retarder; 72. a polarizing reflective element; 73. a first polarizing element; 74. an anti-reflection element; 01. and (5) human eyes.

Detailed Description

Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise.

The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application, its application, or uses.

Techniques and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate.

In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

The optical module and the wearable device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

According to one aspect of embodiments of the present application, an optical module is provided, which may be suitable for application to a wearable device. The wearable device is for example a head mounted display device (Head mounted display, HMD), such as a VR head mounted display device. The VR head-mounted display device includes, for example, VR smart glasses or VR smart helmets, and the specific form of the VR head-mounted display device in the embodiment of the present application is not limited thereto.

Referring to fig. 1 and 2, the optical module provided in this embodiment of the present application includes an imaging lens group, and a beam splitting element 6, a first phase retarder 71 and a polarization reflecting element 72 disposed between optical paths of the imaging lens group, where the first phase retarder 71 is located between the beam splitting element 6 and the polarization reflecting element 72. The optical module further comprises a display assembly, the display assembly comprises a first display screen 1 and a second display screen 2, the first display screen 1 and the second display screen 2 are arranged in vertical symmetry with respect to an optical axis of the imaging lens group, a target interval L is arranged between the first display screen 1 and the second display screen 2, and the target interval L is more than or equal to 1.5mm.

According to the embodiment of the present application, an optical module is provided, which is based on a folded optical path (path). Specifically, referring to fig. 1 and 2, the beam splitting element 6, the first phase retarder 71, the polarization reflecting element 72, and the like are disposed between the lenses in the imaging lens group, so as to form a folded optical path for the optical module; wherein the first phase retarder 71 is to be located between the light splitting element 6 and the polarizing reflecting element 72.

According to the optical module provided in the above embodiment of the present application, the display assembly includes two display screens, that is, the first display screen 1 and the second display screen 2, which are located at a side far from the human eye 01 (aperture). That is, two display screens are introduced into the optical module, and when the user uses the optical module, an optical scheme is formed in which a single eye can correspond to the two display screens, and the design can increase the field angle (FOV value) of the optical module.

For example, the optical module provided in the embodiments of the present application, where the display assembly includes two display screens with a size of 1.03 inches. At this time, the formed optical module can realize a field angle of 100 °.

In the optical module provided in the foregoing embodiment of the present application, the first display screen 1 and the second display screen 2 corresponding to the single eye (the left eye 01 in fig. 1) of the user are designed to be arranged symmetrically up and down with respect to the optical axis of the imaging lens group during layout, see fig. 1. And, a certain interval needs to be reserved between the first display screen 1 and the second display screen 2, so that the assembly of the two display screens is convenient. This is because: the display screen itself has a certain physical size, and if two display screens are assembled next to each other, the two display screens may interfere with each other to cause impossible arrangement, which may cause a difficulty in installing the display assembly.

According to the optical module provided in the embodiment of the present application, the optical path diagram of the optical module may also refer to fig. 1, the incident light (for example, circularly polarized light) emitted by the first display screen 1 and the second display screen 2 enters the imaging lens group, the light may be reflected back and then exit in the imaging lens group, and finally a high-definition picture may be displayed in the human eye 01 located on the left side, so that the picture texture is better.

The optical module provided by the embodiment of the application is beneficial to achieving the requirements of miniaturization and high-definition imaging of virtual reality display equipment (VR display equipment). That is, the optical imaging requirements of high resolution can be met under the condition of ensuring the small volume of the equipment. Based on the design of small size, the wearing comfort can be improved, and the wearing comfort is not tired even if the wearing comfort is used for a long time.

According to the optical module provided by the embodiment of the application, the optical module is of a folding light path structure, and two display screens symmetrically arranged along the same optical axis are introduced into the optical module, so that a single-eye corresponding double display screen and even a larger view field angle are formed, and the visual experience of a user can be improved. And the whole light path structure is simple in design, and miniaturization and high-quality imaging of the optical module are realized.

The optical module provided in the embodiment of the present application is a folded optical path, where the optical module further includes optical elements for forming the folded optical path, such as the spectroscopic element 6, the first phase retarder 71, and the polarization reflecting element 72, in addition to the imaging lens group. The optical elements (optical films) can be used for forming folding light paths among the lenses of the imaging lens group, so that light rays are folded back in the folding light paths to prolong the propagation paths of the light rays, which is beneficial to final clear imaging and simultaneously beneficial to reducing the volume of the whole optical module.

The optical module provided by the embodiment of the application, for the imaging lens group, the number of lenses used can be flexibly adjusted according to specific needs. Along with the increase of the number of lenses in the folded light path, the imaging quality of the optical module can be improved, but the size and the production cost of the optical module along the optical axis direction (transverse direction) can be affected, so that the optical module has larger size, increased weight and increased cost.

As a more preferable mode, the imaging lens group can comprise 2-3 lenses.

The spectroscopic element 6 is, for example, a semi-transparent and semi-reflective film. The light-splitting element 6 is capable of transmitting a part of light and reflecting another part of light.

Optionally, the reflectance of the light-splitting element 6 is 47% -53%.

The reflectivity and transmissivity of the light-splitting element 6 may be flexibly adjusted according to specific needs, which is not limited in the embodiment of the present application.

Wherein the first phase retarder 71 is for example a quarter wave plate.

Of course, the first retarder 71 may be configured as other retarders such as a half-wave plate, etc. as needed.

In the optical module set forth in the embodiment of the present application, the first phase retarder 71 is disposed in a folded optical path near one side of the human eye 01, so as to change the polarization state of the light. For example for converting linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light.

The polarizing reflection element 72 is, for example, a polarizing reflection film/sheet.

The polarizing reflection element 72 is a polarizing reflector that reflects horizontally linearly polarized light, transmits vertically linearly polarized light, or reflects linearly polarized light at any other specific angle, and transmits linearly polarized light in a direction perpendicular to the angle.

In the embodiment of the present application, the first retarder 71 and the polarization reflecting element 72 cooperate to analyze and transmit light.

It should be emphasized that the optical elements of the beam splitter 6, the first phase retarder 71 and the polarizing reflector 72 may form a folded optical path in the imaging lens group near the human eye 01, and the arrangement positions of the optical elements are flexible, but it is ensured that the first phase retarder 71 is interposed between the beam splitter 6 and the polarizing reflector 72.

In some examples of the present application, when the display assembly displays an image, the first image displayed by the first display screen 1 and the second image displayed by the second display screen 2 have an overlapping area, and the overlapping area is close to the optical axis.

Specifically, referring to fig. 1, the optical module includes two display screens, that is, the first display screen 1 and the second display screen 2, where the first display screen 1 and the second display screen 2 are symmetrically distributed about the optical axis of the imaging lens group, and at this time, the image content displayed on the lowermost portion of the first display screen 1 located above and the image content displayed on the uppermost portion of the second display screen 2 located below are consistent, so that it is ensured that the image displayed in the human eye 01 (monocular of the user) is not broken, that is, the integrity of the imaging image is ensured.

In some examples of the present application, the imaging lens group includes at least one lens, and the optical power of the at least one lens is positive.

Specifically, the imaging lens group located on the human eye 01 side may include, for example, only one lens, and may include two or more lenses. The smaller the number of lenses, the lower the weight of the entire optical module, while the size and production cost can be reduced.

In view of improving the imaging quality, a larger number of lenses, for example, 2 to 3 lenses, may be designed in the imaging lens group, which is not limited in the embodiment of the present application.

In addition, imaging can be performed only when the optical power of the lens in the imaging lens group is positive.

In some examples of the present application, referring to fig. 1, the imaging lens group includes a first lens 3 and a second lens 4 that are disposed adjacently and at intervals, and the focal powers of the first lens 3 and the second lens 4 are positive. The first lens 3 is located on the side close to the display assembly and the second lens 4 is located on the side remote from the display assembly. The first lens 3 includes a first surface 31 and a second surface 32, the first surface 31 is close to the display component, the second surface 32 is far away from the display component, and the first surface 31 and the second surface 32 are rotationally symmetrical about the optical axis.

The first surface 31 and the second surface 32 of the first lens 3 are designed to be rotationally symmetrical about the optical axis, respectively, so that the difficulty in machining the lens can be reduced.

The first surface 31 and the second surface 32 form a target angle θ, for example: θ is more than 0 and less than or equal to 20 degrees.

Specifically, referring to fig. 1, the imaging lens group may include two optical lenses, that is, the first lens 3 and the second lens 4 in the above example; wherein the first lens 3 comprises a first surface 31 and a second surface 32. The first surface 31 and the second surface 32 may be, for example, planar, both surfaces being rotationally symmetrical about the optical axis; and, the two surfaces have a certain included angle, the included angle range is 0< θ+.20°, and the included angle range affects the distance (target distance L) between the first display screen 1 and the second display screen 2. This is because, in the case where the first surface 31 and the second surface 32 are both planar, the first lens 3 corresponds to a prism which is capable of upwardly deflecting the passing central ray, so that two display screens can be separately disposed, and the two display screens do not affect each other when assembled.

It should be emphasized that the target angle θ is related to the distance between the two display screens and the imaging quality of the center of the optical module. Therefore, the target included angle θ is not easy to be too large, that is, is not easy to exceed 20 °, otherwise, the center imaging quality cannot be considered while the reasonable distance between the first display screen 1 and the second display screen 2 is controlled, which affects the assembly and layout of the whole display assembly, and also affects the visual experience of the user, in particular, the imaging effect of the center field of view is reduced.

For example, when the target included angle θ is designed to be 15 °, the distance between the first display screen 1 and the second display screen 2 is 1.5mm, which satisfies the above-mentioned dimension design of the target interval L, and can give consideration to the imaging quality of the central field of view.

For another example, when the target angle θ is 20 °, the distance between the first display screen 1 and the second display screen 2 is greater than 2mm, which satisfies the size design of the target interval L, but the center imaging quality is degraded. Therefore, the target angle θ should be controlled as small as 20 ° or less.

As a more preferable mode of the present application, the target included angle θ is 5.5 °.

Optionally, the beam splitting element 6 is disposed on a side of the second lens 4 near the display component, and the first phase retarder 71 and the polarization reflecting element 72 are sequentially disposed on a side of the second lens 4 far from the display component.

An imaging lens group provided according to the above example of the present application includes a first lens 3 and a second lens 4; the second lens 4 is located at a side close to the human eye 01, referring to fig. 1, and each optical element forming a folded optical path is designed and distributed at two sides of the second lens 4, so that the light can be folded back at the side close to the human eye 01 to prolong the optical path, which is beneficial to improving the final imaging quality. Furthermore, lenses can be added directly to the first lens 3 and the display assembly without redesigning the folded light path.

Specifically, referring to fig. 1 and 2, the beam splitting element 6 is disposed on the surface of the second lens 4 near the display component. The optical module further comprises a first polarizing element 73; the first retarder 71, the polarizing reflection element 72, and the first polarizing element 73 are sequentially stacked to form a composite film 7, and the composite film 7 is disposed on a surface of the second lens 4 away from the display unit.

In the above example, the optical elements constituting the folded optical path are attached to different lenses. Thus, the assembly difficulty of the optical module is reduced.

Of course, the beam splitting element 6, the first phase retarder 71 and the polarization reflecting element 72 may be respectively disposed on a flat glass (light-transmitting support member) and then be disposed as independent devices in the optical path, which is not limited in the embodiment of the present application.

Optionally, the imaging lens group includes a first lens 3 and a second lens 4, and the refractive index and the dispersion coefficient of the materials used for the two lenses are as follows: 1.4< n <2.0, 20< v <75.

For example, the refractive index n=1.75 of the first lens 3, and the dispersion coefficient v=52.4.

For example, the refractive index n=1.54 of the second lens 4, and the dispersion coefficient v=56.3.

The imaging quality of the optical module can be improved by adjusting the refractive index and the dispersion coefficient of the two lenses to be matched.

Optionally, the central thickness range of the first lens 3 is: 1mm < t1<10mm, comprising two optical faces, see fig. 1, a first surface 31 and a second surface 32, respectively, which are aspherical or planar.

The first surface 31 and the second surface 32 may be provided with an anti-reflection film, for example. The anti-reflection film can reduce reflection, reduce reflection energy and improve light efficiency utilization rate. The anti-reflection film can be formed on the optical component in a sticking or coating mode to form interfaces, so that the transmittance is increased, the reflectivity is reduced, the image distortion is reduced, a user can enjoy clearer image quality, and the glare is reduced.

Optionally, the optical power Φ1 of the first lens 3 is 0< Φ1<0.1.

Optionally, the center thickness range of the second lens 4 is: 3mm < t2<8mm, comprising two optical faces, see fig. 1, a third face 41 and a fourth face 42, respectively, which are aspherical or planar.

Specifically, the third surface 41 is provided with a spectroscopic element 6 (e.g., a transflective film), and the fourth surface 42 is provided with a composite film 7, and the composite film 7 includes, for example, an antireflection element 74, a first phase retarder 71 (e.g., a 1/4 wave plate), a polarizing reflection element 72 (e.g., a polarizing reflection film, P-light permeable, S-light permeable), and a first polarizing element 73 (e.g., a polarizing film, P-light permeable). Wherein, the anti-reflection element 74 can reduce reflection, reduce reflection energy and improve light efficiency utilization. The first polarizing element 73 may reduce stray light.

Optionally, the optical power Φ2 of the second lens 4 is 0< Φ1<0.1.

For example, the optical power Φ2 of the second lens 4 is 0.0057.

The above example provides an optical module, see fig. 1, in which the light propagates as follows:

the circularly polarized light (natural light may be emitted and converted into circularly polarized light) emitted from the first display screen 1 and the second display screen 2 is transmitted through the first lens 3 and the second lens 4, becomes linearly polarized light (S-light) through the first phase retarder 71 on the fourth surface 42 of the second lens 4, is reflected by the polarizing reflection element 72, becomes circularly polarized light through the first phase retarder 71, is reflected by the light splitting element 6 on the third surface 41 of the second lens 4, becomes linearly polarized light (P-light) through the first phase retarder 71, is transmitted through the polarizing reflection element 72, the first polarizing element 73, and the antireflection element 74, and is then injected into the human eye 01 to image.

In some examples of the present application, the imaging lens group is not limited to include the first lens 3 and the second lens 4, and the imaging lens group further includes a third lens 5, see fig. 7, where the third lens 5 is located between the first lens 3 and the display component, and the first lens 3, the second lens 4, and the third lens 5 are located on the same optical axis, and the optical power of the third lens 5 is positive.

That is, the imaging lens group may include three optical lenses, and the three optical lenses cooperate with each other to improve imaging quality.

In the imaging lens group, the newly added third lens 5 is located at the side of the first lens 3 away from the second lens 4, that is, the third lens 5 is close to the display component.

The center thickness range of the third lens 5 is, for example: 3mm < t3<10mm, comprising two optical faces. Specifically, referring to fig. 3, the third lens 5 includes a fifth surface 51 and a sixth surface 52, and the two optical surfaces are aspheric or planar.

The two optical surfaces of the third lens 5 may be provided with an antireflection film layer, for example.

The third lens 5 has an optical power range of, for example, 0< phi 3<0.1.

For example, the third lens 5 has an optical power of 0.009.

When the third lens 5 is introduced into the imaging lens group, the optical parameters of the first lens 3 can be kept unchanged; the central thickness range of the second lens 4 is designed as 2mm < t2<8mm, the two optical surfaces of the second lens can be aspheric or planar, the third surface 41 of the second lens 4 is provided with a light splitting element 6, the fourth surface 42 of the second lens 4 is provided with a composite film 7, and the focal power phi 2 range of the second lens 4 is as follows: 0< phi 2<0.1, for example 0.0056.

In the case where the third lens 5 is introduced into the imaging lens group, the optical path propagation path principle thereof is the same as that of the two lenses included in the imaging lens group.

In one example, the imaging lens group includes a first lens 3, a second lens 4, and a third lens 5, referring to fig. 7, the first lens 3 is located between the second lens 4 and the third lens 5, and the optical power Φ1 of the first lens 3 is: phi 1 is more than or equal to 0.01; the optical power phi 2 of the second lens 4 is: 0< phi 2<0.1; the optical power phi 3 of the third lens 5 is: phi 3 is more than or equal to 0 and less than or equal to 0.1.

In some examples of the present application, the effective focal length EFL of the optical module is 20mm to 30mm.

In some examples of the present application, the total optical system length TTL of the optical module is 15mm to 30mm.

The effective focal length and the optical total length of the optical module are smaller, so that the optical module can have high-definition imaging performance under a small volume, and wearing comfort and visual experience of a user can be better improved.

For example, in the case where the imaging lens group includes only the first lens 3 and the second lens 4, the effective focal length of the formed optical module is 27.2mm, and the total length of the system is 26.8mm.

For another example, in the case where the imaging lens group includes the first lens 3, the second lens 4, and the third lens 5, the effective focal length of the formed optical module is 24.2mm, and the total length of the system is 27.5mm.

In some examples of the present application, the first display screen 1 and the second display screen 2 are configured to be capable of emitting circularly polarized light or natural light; when the light rays emitted by the first display screen 1 and the second display screen 2 are natural light, overlapping elements (not shown in fig. 1 and 2, and added when needed) are respectively arranged on the light emitting sides of the first display screen 1 and the second display screen 2 to convert the natural light into circularly polarized light; wherein the superposition element comprises at least a second phase retarder and a second polarizing element.

It should be noted that, the incident light entering the imaging lens group should be circularly polarized light. When the first display screen 1 and the second display screen 2 emit natural light, the natural light needs to be converted into polarized light first, and then the natural light is emitted into the imaging lens group on the left side after being converted into circularly polarized light, and finally the light emitted by the imaging lens group is emitted into human eyes 01 for imaging.

The device for converting natural light into circularly polarized light is the above-mentioned lamination sheet. Specifically, the lamination sheet may include, for example, two second phase retarders and a second polarizing element disposed between the two phase retarders. At this time, the first display screen 1 and the second display screen 2 respectively emit natural light, and the natural light is still natural light after passing through one second phase retarder, and is changed into linear polarized light after passing through the second polarizing element, and is changed into circular polarized light after passing through the other second phase retarder.

Alternatively, referring to fig. 1, the first light-emitting surface 11 of the first display screen 1 and the second light-emitting surface 21 of the second display screen 2 may be provided with a screen protection glass. At this time, the light rays emitted by the first display screen 1 and the second display screen 2 respectively pass through the respective screen protection glass and then enter the lamination sheet to perform polarization state conversion.

The optical module provided in the embodiments of the present application will be described in detail by embodiments 1 and 2.

Example 1

Referring to fig. 1 and 2, the optical module includes an imaging lens set, a beam splitter 6 disposed in the imaging lens set, a first phase retarder 71, a polarization reflection element 72, and a first polarization element 73; the imaging lens group comprises a first lens 3 and a second lens 4 which are adjacent and arranged at intervals, wherein the focal power phi 1 of the first lens 3 is as follows: phi 1 is more than or equal to 0.01; the optical power phi 2 of the second lens 4 is 0.0057;

the first lens 3 is positioned on the side close to the display assembly, and the second lens 4 is positioned on the side far from the display assembly; the first lens 3 comprises a first surface 31 and a second surface 32, the first surface 31 is close to the display component, the second surface 32 is far away from the display component, and the first surface 31 and the second surface 32 are rotationally symmetrical about the optical axis; the first surface 31 and the second surface 32 form a target included angle θ, and the target included angle θ is 5.5 °;

the light splitting element 6 is arranged on the surface of the second lens 4, which is close to the display component; the optical module further comprises a first polarizing element 73 and an anti-reflection element 74; the first retarder 71, the polarizing reflection element 72, the first polarizing element 73 and the antireflection element 74 are sequentially stacked to form a composite film 7, and the composite film is disposed on a surface of the second lens 4 away from the display assembly.

Table 1 shows specific optical parameters of each lens in the optical module provided in this embodiment 1.

TABLE 1

For the optical module provided in the above embodiment 1, the optical performance thereof may be as shown in fig. 3 to 6:

fig. 3 is an MTF graph of an optical module, fig. 4 is a schematic view of a dot column of the optical module, fig. 5 is a field curvature distortion graph of the optical module, and fig. 5 is a vertical axis chromatic aberration graph of the optical module.

The MTF graph is a modulation transfer function graph, and the imaging definition of the optical module is represented by the contrast of the black-white line pair. Referring to FIG. 3, the center MTF was >0.5 at 78lp/mm, and the imaging was clear.

The point column graph refers to a dispersion graph scattered in a certain range, which can be used for evaluating the imaging quality of an optical module, after a plurality of light rays emitted from one point pass through the optical module, the intersection point of the light rays and an image plane is not concentrated at the same point due to aberration. Referring to fig. 4, the maximum value of the image points in the point column image is less than 42 μm.

The field curvature map reflects the difference of image plane positions of the clear images of different fields of view, and the field curvature maximum value is smaller than 5mm, as shown in fig. 5.

The vertical axis chromatic aberration is also called as chromatic aberration of magnification, and mainly refers to a multi-color principal ray of an object side, which is changed into a plurality of rays when exiting from an image side due to chromatic dispersion of a refraction system, and the difference of focus positions of blue light and red light on an image plane. Referring to fig. 6, the maximum color difference value of the optical module is less than 260 μm.

Example 2

Referring to the optical module shown in fig. 7, the optical module shown in embodiment 1 is different from the optical module shown in embodiment 1 in that a third lens 5 is introduced in the imaging lens group, the third lens 5 is located between the first lens 3 and the display assembly, and the optical power of the third lens 5 is 0.009.

Table 2 shows specific optical parameters of each lens in the optical module provided in this embodiment 2.

TABLE 2

For the optical module provided in the above embodiment 2, the optical performance of the optical module may be as shown in fig. 8 to 11:

fig. 8 is an MTF graph of an optical module, fig. 9 is a schematic view of a dot column of the optical module, fig. 10 is a field curvature distortion graph of the optical module, and fig. 11 is a vertical axis chromatic aberration graph of the optical module.

The MTF graph is a modulation transfer function graph, and the imaging definition of the optical module is represented by the contrast of the black-white line pair. Referring to FIG. 8, the center MTF was >0.6 at 78lp/mm, and the imaging was clear.

The point column graph refers to a dispersion graph scattered in a certain range, which can be used for evaluating the imaging quality of an optical module, after a plurality of light rays emitted from one point pass through the optical module, the intersection point of the light rays and an image plane is not concentrated at the same point due to aberration. Referring to fig. 9, the maximum value of the image points in the point column image is less than 9 μm.

The field curvature map reflects the difference of image plane positions of the clear images of different fields of view, and the field curvature maximum value is smaller than 6mm, as shown in fig. 10.

The vertical axis chromatic aberration is also called as chromatic aberration of magnification, and mainly refers to a multi-color principal ray of an object side, which is changed into a plurality of rays when exiting from an image side due to chromatic dispersion of a refraction system, and the difference of focus positions of blue light and red light on an image plane. Referring to fig. 11, the maximum color difference value of the optical module is less than 260 μm.

According to another aspect of the embodiments of the present application, there is also provided a head-mounted display device including a housing, and an optical module as described above.

The head-mounted display device is, for example, a VR head-mounted device, including VR glasses or VR helmets, and the embodiment of the present application does not specifically limit this.

The specific implementation manner of the head-mounted display device in this embodiment may refer to each embodiment of the optical module, so at least the technical solution of the foregoing embodiment has all the beneficial effects, which are not described herein in detail.

The foregoing embodiments mainly describe differences between the embodiments, and as long as there is no contradiction between different optimization features of the embodiments, the embodiments may be combined to form a better embodiment, and in consideration of brevity of line text, no further description is given here.

Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present application. The scope of the application is defined by the appended claims.

Claims

1. An optical module, characterized in that the optical module comprises an imaging lens group, a light splitting element (6), a first phase retarder (71) and a polarization reflecting element (72) which are arranged between optical paths of the imaging lens group, and the first phase retarder (71) is positioned between the light splitting element (6) and the polarization reflecting element (72);

the optical module further comprises a display assembly, the display assembly comprises a first display screen (1) and a second display screen (2), the first display screen (1) and the second display screen (2) are arranged symmetrically up and down relative to the optical axis of the imaging lens group, a single-eye corresponding double display screen is formed, a target interval L is arranged between the first display screen (1) and the second display screen (2), and the target interval L is more than or equal to 1.5mm;

when the display assembly displays images, a first image displayed by the first display screen (1) and a second image displayed by the second display screen (2) have an overlapping area, and the overlapping area is close to the optical axis;

the angle of view of the optical module can reach 100 degrees.

2. The optical module of claim 1, wherein the imaging lens group comprises at least one lens, and wherein the optical power of the at least one lens is positive.

3. The optical module according to claim 2, wherein the imaging lens group comprises a first lens (3) and a second lens (4) which are adjacent and arranged at intervals, and the focal power of the first lens (3) and the focal power of the second lens (4) are positive;

the first lens (3) is positioned on the side close to the display assembly, and the second lens (4) is positioned on the side far from the display assembly;

the first lens (3) comprises a first surface (31) and a second surface (32), the first surface (31) is close to the display component, the second surface (32) is far away from the display component, and the first surface (31) and the second surface (32) are rotationally symmetrical about the optical axis.

4. An optical module according to claim 3, characterized in that the first surface (31) forms a target angle θ with the second surface (32), the target angle θ being: θ is more than 0 and less than or equal to 20 degrees.

5. An optical module according to claim 3, wherein the light splitting element (6) is disposed on a side of the second lens (4) close to the display assembly, and the first phase retarder (71) and the polarization reflecting element (72) are sequentially disposed on a side of the second lens (4) away from the display assembly.

6. An optical module according to claim 3, characterized in that the light splitting element (6) is arranged on the surface of the second lens (4) close to the display assembly;

the optical module further comprises a first polarizing element (73);

the first phase retarder (71), the polarized reflecting element (72) and the first polarized element (73) are sequentially stacked to form a composite film (7), and the composite film (7) is arranged on the surface, far away from the display assembly, of the second lens (4).

7. An optical module according to claim 3, wherein the imaging lens group further comprises a third lens (5), the third lens (5) being located between the first lens (3) and the display component, and the first lens (3), the second lens (4) and the third lens (5) being located on the same optical axis, the optical power of the third lens (5) being positive.

8. An optical module according to claim 7, characterized in that the optical power Φ1 of the first lens (3) is: phi 1 is more than or equal to 0.01; the optical power phi 2 of the second lens (4) is: 0< phi 2<0.1; the optical power phi 3 of the third lens (5) is: phi 3 is more than or equal to 0 and less than or equal to 0.1.

9. The optical module of claim 1, wherein the effective focal length EFL of the optical module is 20mm to 30mm.

10. The optical module of claim 1, wherein the total optical system length TTL of the optical module is 15mm to 30mm.

11. The optical module according to claim 1, characterized in that the first display screen (1) and the second display screen (2) are configured to be capable of emitting circularly polarized light or natural light;

when the light rays emitted by the first display screen (1) and the second display screen (2) are natural light, overlapping elements are respectively arranged on the light emitting sides of the first display screen (1) and the second display screen (2) and used for converting the natural light into circularly polarized light; wherein the superposition element comprises at least a second phase retarder and a second polarizing element.

12. A wearable device, comprising:

a housing; and

the optical module of any one of claims 1-11.