CN117647895A

CN117647895A - Optical module and near-to-eye display device

Info

Publication number: CN117647895A
Application number: CN202311833284.8A
Authority: CN
Inventors: 孙志文; 郑鹏磊
Original assignee: Thunderbird Innovation Technology Shenzhen Co ltd
Current assignee: Thunderbird Innovation Technology Shenzhen Co ltd
Priority date: 2023-12-26
Filing date: 2023-12-26
Publication date: 2024-03-05

Abstract

The application provides an optical module and a near-eye display device, wherein the optical module comprises a first lens, a second lens, a first polarization reflecting element, a first phase retarder, a light splitting element, a second phase retarder and a second polarization reflecting element; the first lens is configured to be close to the light emitting side of the display screen, the first polarized reflecting element is arranged on the first lens, and the first polarized reflecting element is configured to reflect light rays emitted by the display screen to the light emitting side of the first lens; the second lens is arranged on the light-emitting side of the first lens, and the first phase retarder, the light splitting element, the second phase retarder and the second polarization reflecting element are sequentially arranged on a light path formed by the first lens and the second lens. The optical module is small in size and can realize a large angle of view.

Description

Optical module and near-to-eye display device

Technical Field

The present disclosure relates to optical imaging technology, and more particularly, to an optical module and a near-to-eye display device.

Background

With the development of computer technology and display technology, virtual Reality (VR) technology of experiencing a Virtual world through a computer simulation system and augmented Reality (Augmented Reality, AR) technology and Mixed Reality (MR) technology of fusing display contents into a real environment background have been rapidly developed, and near-to-eye display is an important technical hotspot for the development of VR, AR and MR technologies.

The field angle of the optical system in the existing near-eye display device is directly related to the screen size of the display, and a larger field angle needs to be matched with a larger-sized display screen, so that the size of the near-eye display device also becomes larger.

Therefore, there is a need for a near-eye display device that is small in size and that can achieve a large viewing angle.

Disclosure of Invention

The embodiment of the application provides an optical module and a near-to-eye display device, wherein the optical module is small in size and can realize a large field angle.

The embodiment of the application provides an optical module, which comprises a first lens, a second lens, a first polarization reflecting element, a first phase retarder, a light splitting element, a second phase retarder and a second polarization reflecting element;

the first lens is configured to be close to the light emergent side of the display screen, the first polarization reflecting element is arranged on the first lens, and the first polarization reflecting element is configured to reflect light rays emergent from the display screen to the light emergent side of the first lens;

the second lens is arranged on the light emitting side of the first lens, and the first phase retarder, the light splitting element, the second phase retarder and the second polarization reflecting element are sequentially arranged on a light path formed by the first lens and the second lens.

In some embodiments, the first phase retarder is disposed on the light emitting side of the first lens, the light splitting element is disposed on a side of the first phase retarder away from the first lens, and the second phase retarder and the second polarizing reflection element are sequentially disposed on the light emitting side of the second lens.

In some embodiments, the first lens has a first side, a second side, and a third side that are angled with respect to each other, the first side, the second side, and the third side are sequentially connected, the first side is the light-emitting side, the second side is the light-entering side, and the first polarizing reflective element is disposed on the third side.

In some embodiments, the optical module further includes a third lens disposed on a side of the first polarizing reflective element remote from the first lens, the side of the third lens remote from the first lens being approximately parallel to the third side.

In some embodiments, the first lens is spaced apart from the third lens.

In some embodiments, the second lens has a fourth side and a fifth side opposite, the fourth side being a curved surface, the fifth side being a plane, the fifth side being disposed at and parallel to the light exit side of the first lens.

In some embodiments, the optical module further includes a fourth lens disposed on a side of the second polarizing reflective element remote from the second lens, the side of the fourth lens remote from the second lens being approximately parallel to the fifth side.

In some embodiments, the second lens is spaced apart from the fourth lens.

In some embodiments, the optical module further includes a fifth lens disposed at the light entrance side of the first lens, the fifth lens configured to be disposed between the display screen and the first lens.

The embodiment of the application also provides a near-eye display device, which comprises:

a display screen;

the optical module is the optical module and is arranged on the light emitting side of the display screen.

The optical module provided by the embodiment of the application comprises a first lens, a second lens, a first polarized reflecting element, a light splitting element, a second phase retarder and a second polarized reflecting element. The first lens is configured to be close to the light emitting side of the display screen, the first polarization reflection element is arranged on the first lens, and the first polarization reflection element is configured to reflect light rays emitted by the display screen to the light emitting side of the first lens, so that the relative position between the display screen and the optical module can be changed, the thickness of the optical module is shortened, and the size of the optical module is reduced. The second lens is arranged on the light emitting side of the first lens, and the first phase retarder, the light splitting element, the second phase retarder and the second polarization reflecting element are sequentially arranged on a light path formed by the first lens and the second lens. The first polarization reflecting element, the light splitting element, the second phase retarder and the second polarization reflecting element are commonly used for folding the light path, the light path is increased by repeatedly turning back the light, and the effective light path can be increased to three times, so that the volume of the optical module is reduced, and the visual angle field is enlarged.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained from these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of a first structure of an optical module according to an embodiment of the disclosure.

Fig. 2 is a schematic diagram of a folded optical path provided in an embodiment of the present application.

Fig. 3 is an MTF graph of an optical module provided in an embodiment of the present application.

Fig. 4 is a schematic diagram of a second structure of an optical module according to an embodiment of the present application.

Fig. 5 is a schematic structural diagram of a near-eye display device according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

In the prior art, the Birdbath (bird bowl) optical module is a main near-to-eye display optical scheme at present, and has the advantages of high image quality, light weight and low cost, but the field angle of the Birdbath optical module is directly related to the screen size and the module volume, a larger field angle needs a larger-sized display screen, and the module volume is also larger, so that difficulty is brought to the production. Generally, the field angle of the Birdbath optical module is between 40-50 degrees, and the matching screen is 0.4-0.7 inches. With the increasing demands of consumers, there is a need for an optical module and a near-eye display device that can have a larger viewing angle and a smaller size.

The embodiment of the application provides an optical module and a near-to-eye display device, wherein the optical module is small in size and can realize a large field angle. The following description is made in detail with reference to the accompanying drawings.

Referring to fig. 1, fig. 1 is a schematic diagram of a first structure of an optical module 100 according to an embodiment of the disclosure.

The embodiment of the application provides an optical module 100, where the optical module 100 includes a first lens 10, a second lens 20, a first polarization reflecting element 31, a beam splitter 33, a second phase retarder 34, and a second polarization reflecting element.

The first lens 10 is arranged close to the light exit side of the display screen 200. The first polarization reflecting element 31 is disposed on the first lens 10, and the first polarization reflecting element 31 is configured to reflect the light emitted from the display screen 200 to the light emitting side of the first lens 10.

Since the first polarization reflection element 31 can change the outgoing direction of the light, the relative position between the screen and the first lens 10 can be changed, so that the display screen 200 can be disposed on the upper side or the lower side of the optical module 100, the lateral distance of the optical module 100 can be reduced, the volume can be further reduced, and the occupied space of the optical module 100 can be reduced. If the optical module 100 is applied to AR equipment, the display screen 200 can be prevented from blocking the view.

The second lens 20 is disposed on the light-emitting side of the first lens 10. The thickness of the optical module 100 is 14mm, the materials of the first lens 10 and the second lens 20 are optical resins, and the surface types of the first lens 10 and the second lens 20 are aspheric.

The first polarizing reflection element 31, the first phase retarder 32, the spectroscopic element 33, the second phase retarder 34, and the second polarizing reflection element 35 are disposed in this order along the optical path formed by the first lens 10 and the second lens 20. The first polarizing reflection element 31 and the second polarizing reflection element 35 have linear polarization directions, the light splitting element 33 is a half-transmissive film, and the second phase retarder 34 can convert linearly polarized light into circularly polarized light.

The first polarizing reflection element 31 and/or the second polarizing reflection element 35 may be 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 perpendicular to the angle.

The spectroscopic element 33 may be a semi-transparent and semi-reflective film. The light-splitting element 33 may transmit a portion of the light, and reflect another portion of the light. Alternatively, the reflectance of the spectroscopic element 33 may be 47% to 53%. The reflectivity and transmissivity of the light-splitting element 33 may be flexibly adjusted according to specific needs, which is not limited in the embodiment of the present application.

The first phase retarder 32 and/or the second phase retarder 34 may be used to change the polarization state of light. The first and second phase retarders 32 and 34 may be first lambda/4 wave plates. For example, the first phase retarder 32 and/or the second phase retarder 34 may be used to convert linearly polarized light to circularly polarized light or circularly polarized light to linearly polarized light.

As described above, the first polarization reflecting element 31, the first phase retarder 32, the spectroscopic element 33, the second phase retarder 34, and the second polarization reflecting element 35 cooperate with each other, and the light can be folded and transmitted.

For example, referring to fig. 2, fig. 2 is a schematic diagram of a folded optical path according to an embodiment of the present application. The first and second polarizing reflection elements 31 and 35 may each be a P-type light polarizer capable of transmitting second linearly polarized light (P-type polarized light) and reflecting first linearly polarized light (S-type polarized light). The spectroscopic element 33 is a semi-transparent semi-reflective film, and the first phase retarder 32 and the second phase retarder 34 are first λ/4 plates. The first linearly polarized light is reflected by the first polarizing reflection element 31 to be formed into first linearly polarized light, and then passes through the first phase retarder 32, at which time the first linearly polarized light is changed into right circularly polarized light. Then, the light transmitted through the light-splitting element 33 passes through the second phase retarder 34 after passing through the light-splitting element 33 for a certain distance, and the right-handed circularly polarized light is changed into second linearly polarized light. When the light reaches the second polarization reflection element 35, the second linearly polarized light is totally reflected by the second polarization reflection element 35, and passes through the second phase retarder 34 again, at which time the second linearly polarized light becomes right-handed circularly polarized light, the right-handed circularly polarized light passes through the light splitting element 33, and the light of the reflected portion is converted into left-handed circularly polarized light. The right circularly polarized light passes through the second phase retarder 34 again, and becomes first linearly polarized light, and the light exits in the same polarization direction as the second polarization reflecting element 35.

When the optical module 100 is applied to the augmented reality (Augmented Reality, AR) technology, the natural light passes through the first polarizing reflective element 31 to form the second linearly polarized light, and passes through the first phase retarder 32, and the first linearly polarized light is changed into the left circularly polarized light. Then, the transmitted light passes through the light splitting element 33, and then passes through the second phase retarder 34 after passing a certain distance, at this time, the left circularly polarized light becomes the first linearly polarized light, and the light exits in the same polarization direction as the second polarized reflecting element 35.

The first polarization reflecting element 31, the first phase retarder 32, the beam splitting element 33, the second phase retarder 34, and the second polarization reflecting element 35 are commonly used for folding the optical path, and the optical path is increased by repeatedly folding the light, so that the effective optical path can be increased by three times, thereby reducing the volume of the optical module 100 and enlarging the viewing angle field. In the optical module 100 of the embodiment of the present application, the size of the display screen 200 that is matched with the optical module 100 may be 0.68 inches, and the angle of view of the optical module 100 is 62 °, and the distortion is <1.9%. Referring to fig. 3, fig. 3 is an MTF graph of an optical module according to an embodiment of the present application. The contrast ratio of the black-and-white line pair characterizes the imaging sharpness of the optical module 100. The center MTF was >0.3 at 20lp/mm, and the imaging was clear. As can be seen, the optical module 100 provided in the embodiments of the present application can match a smaller sized (0.5 to 0.7 inch) screen, realizing a large angle of view (55 to 65 °) at a smaller thickness (10 to 15 mm).

In addition, when the optical module 100 is applied to the augmented reality (Augmented Reality, AR) technology, the optical module 100 can penetrate natural light, so as to facilitate the implementation of the augmented reality (Augmented Reality, AR) technology. The natural light refers to the light that is reflected to the object, scene, and is about to be reflected into the human eye.

Specifically, the first retarder 32 is disposed on the light-emitting side 11 of the first lens 10, the light-splitting element 33 is disposed on a side of the first retarder 32 away from the first lens 10, and the second retarder 34 and the second polarizing reflection element 35 are sequentially disposed on the light-emitting side 21 of the second lens 20. It can be seen that the first lens 10 and the second lens 20 play a supporting role, and are used for supporting the first polarization reflecting element 31, the first phase retarder 32, the light splitting element 33, the second phase retarder 34, and the second polarization reflecting element 35 to achieve the functions of reflecting light and folding light.

The spectroscopic element 33 and the second polarizing reflection element 35 are disposed on both sides of the second lens 20, respectively, and the increase in the effective optical path length is proportional to the distance between the spectroscopic element 33 and the second polarizing reflection element 35, that is, the greater the thickness of the second lens 20, the longer the distance between the spectroscopic element 33 and the second polarizing reflection element 35, and the longer the effective optical path length is, which is advantageous for the increase in the effective optical path length.

In some embodiments, the first lens 10 has a first side 13, a second side 14, and a third side 15 that are angled with respect to each other, the first side 13, the second side 14, and the third side 15 being connected in sequence. The first side 13 is the light-emitting side 11, the second side 14 is the light-entering side 12, and the first polarizing reflective element 31 is disposed on the third side 15.

The first polarization reflecting element 31 can function to reflect light. The first polarizing reflection element 31 can reflect light to the first side surface 13 and emit light having a specific polarization direction. The light generated by the display screen 200 may be transmitted through the first lens 10 in a first direction, and the natural light may be projected onto the first lens 10 in a second direction, where the first direction intersects the second direction. Further avoiding the display screen 200 from obscuring the user's view facilitates implementation of augmented reality (Augmented Reality, AR) techniques.

Wherein the light-emitting side of the display surface is adjacent to the second side 14.

In some cases, the light emitted from the display screen 200 can enter the first lens 10 and then be reflected directly on the first polarizing reflective element 31 and then exit from the second side 14. The light exiting the display 200 may be polarized light.

In other cases, the display 200 emits light from the second side 14 into the first lens 10, reflects off the first side 13 of the first lens 10, reflects off the first polarizing reflective element 31 on the third side 15, and emits light from the second side 14.

According to Brewster's law: when incident light is incident on the transparent medium at a certain angle, the reflected light is polarized light (S-polarized light) having a polarization direction perpendicular to the incident plane. According to this law, the light reflected at the first side surface 13 of the first lens 10 is S-polarized light, which is the first linear polarized light described in the above embodiment. In this case, the optical module 100 can avoid the polarization effect of the display screen 200 and the polarizer, which is beneficial to saving cost.

In this embodiment, the relative position between the display screen 200 and the optical module 100 can be adjusted, so that the display screen 200 is moved far away from the human eyes, and the influence of heat generation of the display screen 200 on the user experience is avoided.

In some embodiments, the optical module 100 further includes a third lens 40, where the third lens 40 is disposed on a side of the first polarization reflecting element 31 away from the first lens 10, and a side of the third lens 40 away from the first lens 10 is approximately parallel to the third side 15. It will be appreciated that the side of the third lens 40 remote from the first lens 10 and the third side 15 may be approximately parallel, and difficult to be completely parallel, due to manufacturing errors and mounting errors of the process.

The natural light passes through the third lens 40 and then enters the first lens 10, and the third lens 40 can be set into any shape according to actual needs, so that optical path compensation of the natural light is realized and aberration is reduced. For example, the third lens 40 may be provided in a triangle, a trapezoid, or the like. In the embodiment of the present application, a side of the third lens 40 away from the first lens 10 is an incident side 41 of the third lens 40, a side of the third lens 40 close to the first lens 10 is an emergent side 42 of the third lens 40, and the emergent side 42 of the third lens 40 is approximately parallel to the third side 15 of the first lens 10.

In some cases, referring to fig. 4, fig. 4 is a schematic diagram of a second structure of the optical module 100 according to the embodiment of the present application. The first lens 10 and the third lens 40 are disposed at a distance, so that the adhesive between the first lens 10 and the second lens 20 can avoid the influence on the light propagation process.

In other cases, the first lens 10 and the third lens 40 may be adhered, and the relative positions of the first lens 10 and the third lens 40 are firmer.

In some embodiments, the second lens 20 has an opposite fourth side 23 and a fifth side 24, the fourth side 23 being a curved surface and the fifth side 24 being a planar surface. The fourth side 23 is the light exit side 21 of the second lens 20, and the fifth side 24 is the light entrance side 22 of the second lens 20. The second lens 20 may be a convex lens, and may be used to diverge light. The fifth side 24 is disposed at the light-emitting side 11 of the first lens 10 and is approximately parallel to the light-emitting side 11 of the first lens 10, so that the light emitted from the first lens 10 is directly incident into the second lens 20.

The optical module 100 further includes a fourth lens 50, wherein the fourth lens 50 is disposed on a side of the second polarization reflecting element away from the second lens 20, and a side of the fourth lens 50 away from the second lens 20 is approximately parallel to the fifth side 24. The second lens 20 and the fourth lens 50 are located on the same optical axis.

It will be appreciated that the side of the fourth lens 50 remote from the second lens 20 and the fifth side 24 may be approximately parallel, and difficult to be perfectly parallel, due to manufacturing errors and mounting errors of the process.

The light enters the human eye through the fourth lens 50, and the fourth lens 50 can be set into any shape according to actual needs, so as to realize optical path compensation and aberration reduction of the light exiting the second lens 20. The fourth lens 50 may be provided in a triangle, a trapezoid, or the like. In the embodiment of the present application, a side of the fourth lens 50 away from the second lens 20 is an outgoing side 52 of the fourth lens 50, and a side of the fourth lens 50 close to the second lens 20 is an incoming side 51 of the fourth lens 50. The light entrance side 51 of the fourth lens 50 is approximately parallel to the light exit side 21 of the second lens 20.

In some cases, referring to fig. 4, the second lens 20 is spaced apart from the fourth lens 50. The influence of the adhesive between the second lens 20 and the fourth lens 50 on the light propagation process can be avoided.

In other cases, the second lens 20 and the fourth lens 50 may be adhered, and the second lens 20 and the fourth lens 50 are positioned more firmly.

The optical module 100 further includes a fifth lens 60, where the fifth lens 60 is disposed at the light incident side 12 of the first lens 10, and the fifth lens 60 is configured to be disposed between the display screen 200 and the first lens 10. The light emitted from the display screen 200 can enter the first lens 10 after passing through the fifth lens 60, and the fifth lens 60 may be a convex lens for correcting the light path and enlarging the image transmitted by the display screen 200.

Referring to fig. 5, fig. 5 is a schematic structural diagram of a near-eye display device 1 according to an embodiment of the disclosure.

The embodiment of the application also provides a near-eye display device 1, and the near-eye display device 1 may be a virtual reality device, an augmented reality device or a mixed reality device. The near-eye display device 1 includes a display screen 200 and an optical module 100, wherein the optical module 100 is the optical module 100 in the above embodiment, and the optical module 100 is disposed on the light emitting side of the display screen 200.

The display panel 200 can emit three colors of light, such as red light corresponding to a red sub-pixel, blue light corresponding to a blue sub-pixel, and green light corresponding to a green sub-pixel, so as to display a picture. It can be understood that each color propagates in the optical module 100, so that the propagation of the light of each color in the optical module 100 is not disturbed, and the picture viewed through the optical module 100 is more accurate and bright.

The optical module 100 includes a first lens 10, a second lens 20, a first polarization reflecting element 31, a first phase retarder 32, a beam splitter 33, a second phase retarder 34, and a second polarization reflecting element 35. The first lens 10 is disposed near the light emitting side of the display screen 200, the first polarization reflecting element 31 is disposed on the first lens 10, and the first polarization reflecting element 31 is configured to reflect the light emitted from the display screen 200 to the light emitting side 11 of the first lens 10, so that the relative position between the display screen 200 and the optical module 100 can be changed, and the thickness of the optical module 100 is reduced, thereby reducing the volume of the optical module 100. The first polarization reflecting element 31, the first phase retarder 32, the beam splitter 33, the second phase retarder 34, and the second polarization reflecting element 35 are disposed on an optical path formed by the first lens 10 and the second lens 20, and are commonly used for folding the optical path. The increase of the optical path is achieved by repeatedly turning back the light, and the effective optical path can be tripled, thereby reducing the volume of the optical module 100 and expanding the viewing angle field. In the optical module 100 of the embodiment of the present application, the size of the display screen 200 that is matched with the optical module 100 may be 0.68 inches, and the angle of view of the optical module 100 is 62 °, and the distortion is <1.9%. The center MTF was >0.3 at 20lp/mm, and the imaging was clear. As can be seen, the optical module 100 provided in the embodiments of the present application can match a smaller sized (0.5 to 0.7 inch) screen, realizing a large angle of view (55 to 65 °) at a smaller thickness (10 to 15 mm).

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.

In the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more features.

The optical module and the near-eye display device provided by the embodiment of the application are described in detail above. Specific examples are set forth herein to illustrate the principles and embodiments of the present application, with the description of the examples given above only to assist in understanding the present application. Meanwhile, those skilled in the art will have variations in the specific embodiments and application scope in light of the ideas of the present application, and the present description should not be construed as limiting the present application in view of the above.

Claims

1. An optical module is characterized by comprising a first lens, a second lens, a first polarization reflecting element, a first phase retarder, a light splitting element, a second phase retarder and a second polarization reflecting element;

2. The optical module of claim 1, wherein the first phase retarder is disposed on a light-emitting side of the first lens, the light splitting element is disposed on a side of the first phase retarder away from the first lens, and the second phase retarder and the second polarization reflecting element are sequentially disposed on the light-emitting side of the second lens.

3. The optical module of claim 1, wherein the first lens has a first side, a second side, and a third side that are angled with respect to each other, the first side, the second side, and the third side being sequentially connected, the first side being the light exit side, the second side being the light entrance side, the first polarizing reflective element being disposed on the third side.

4. An optical module as recited in claim 3, further comprising a third lens disposed on a side of the first polarizing reflective element remote from the first lens, the side of the third lens remote from the first lens being approximately parallel to the third side.

5. The optical module of claim 4, wherein the first lens is spaced apart from the third lens.

6. The optical module of any one of claims 1 to 5, wherein the second lens has a fourth side and a fifth side opposite to each other, the fourth side being a curved surface, the fifth side being a plane, the fifth side being disposed at and parallel to the light exit side of the first lens.

7. The optical module of claim 6, further comprising a fourth lens disposed on a side of the second polarizing reflective element remote from the second lens, the side of the fourth lens remote from the second lens being approximately parallel to the fifth side.

8. The optical module of claim 7, wherein the second lens is spaced apart from the fourth lens.

9. The optical module of any one of claims 1-5, further comprising a fifth lens disposed at the light entry side of the first lens, the fifth lens configured to be disposed between the display screen and the first lens.

10. A near-eye display device, comprising:

a display screen;

an optical module according to any one of claims 1 to 9, the optical module being disposed on a light-emitting side of the display screen.