WO2023098057A1

WO2023098057A1 - Optical module and head-mounted display device

Info

Publication number: WO2023098057A1
Application number: PCT/CN2022/102064
Authority: WO
Inventors: 宋文宝
Original assignee: 歌尔光学科技有限公司
Priority date: 2021-11-30
Filing date: 2022-06-28
Publication date: 2023-06-08
Also published as: CN114236827A

Abstract

An optical module and an electronic device. The optical module comprises a display unit (6), a first lens (4), a polarization reflector (8), a first phase retarder (9) and an optical splitter (10), wherein the display unit (6) has a light-emitting surface configured to emit incident light; the first lens (4) is arranged in a direction of propagation of the incident light, and the first lens (4) comprises a first surface facing the light-emitting surface and a second surface facing away from the light-emitting surface, the distance between the first surface and the light-emitting surface being set to be greater than or equal to 1.5 mm; and the optical splitter (10) is arranged on one side of the first surface, the polarization reflector (8) is arranged on one side of the second surface, and the first phase retarder (9) is arranged between the polarization reflector (8) and the optical splitter (10). Provided is a solution of a folded optical path, which can effectively reduce the requirement regarding appearance defects of the lens in the folding optical path on the side close to the display unit (6).

Description

An optical module and a head-mounted display device

technical field

The present application relates to the field of optical technology, and more specifically, the present application relates to an optical module and a head-mounted display device.

Background technique

In recent years, augmented reality (Augmented Reality, AR) technology and virtual reality (Virtual Reality, VR) technology have been applied in smart wearable devices and developed rapidly. The core components of augmented reality technology and virtual reality technology are optical modules. Therefore, the quality of the display effect of the optical module will directly determine the quality of the smart wearable device.

In the existing related technologies, a VR device is taken as an example. Some VR devices mostly use an optical module combined with a single-chip lens + display screen (display). However, based on the imaging requirements of the optical path, the distance between the lens and the display screen will be relatively long, which leads to a large size of the VR device, which is not conducive to the miniaturization of the product. It may lead to poor user experience when wearing the device. In order to improve this problem, the folded optical path scheme came into being. Nowadays, many smart wearable devices such as VR devices have adopted the folding optical path solution.

The folding optical path scheme can effectively reduce the total length of the optical system, but in the entire optical path structure, the lens (lens) on the side close to the display screen is relatively close to the light-emitting surface of the display screen, which will cause defects in the appearance of the lens. Other optics on one side of the screen are then magnified, making it easier for the human eye to notice, which will lead to poor imaging.

Contents of the invention

The purpose of this application is to provide a new technical solution for an optical module and a head-mounted display device.

According to one aspect of the present application, an optical module is provided. The optical module includes:

a display unit, the display unit has a light-emitting surface, and the light-emitting surface is used to emit incident light;

A first lens, the first lens is arranged along the propagating direction of the incident light, the first lens includes a first surface facing the light-emitting surface and a second surface away from the light-emitting surface, the first surface The distance from the light-emitting surface is set to ≥1.5mm;

The optical module also includes a polarizing reflector, a first phase retarder and a beam splitter, the beam splitter is arranged on one side of the first surface, and the polarizing reflector is arranged on one side of the second surface , the first phase retarder is disposed between the polarizing reflector and the beam splitter.

Optionally, the distance between the first surface of the first lens and the light-emitting surface of the display unit is set to T1, the distance between the beam splitter and the polarizing reflector is set to T2, and the T1 The ratio to the T2 is set to be 0.1-1.6.

Optionally, the optical module further includes a protective sheet, and the protective sheet is arranged on one side of the light-emitting surface of the display unit;

The protective sheet includes a rear surface facing the light-emitting surface and a front surface facing away from the light-emitting surface, and the distance between the rear surface of the protective sheet and the light-emitting surface is set to be ≥ 1 mm.

Optionally, the optical module further includes a second phase retarder and a polarizer;

The polarizer is arranged on one side of the front surface of the protective sheet;

The second phase retarder is disposed between the beam splitter and the polarizer.

Optionally, the polarizer is a linear polarizer.

Optionally, the polarizer has a transmission axis through which light passes, and an included angle between the transmission axis of the polarizer and the fast axis or slow axis of the second phase retarder is set to 45°.

Optionally, at least one of the first phase retarder and the second phase retarder is a quarter wave plate.

Optionally, the optical module further includes a second lens, the second lens is arranged on one side of the second surface of the first lens, and the second lens and the first lens are located on the same optical axis superior;

The second lens includes a third surface facing the first lens and a fourth surface facing away from the first lens;

The polarizing reflector is disposed on one side of the third surface, and the first phase retarder is disposed on a side of the polarizing reflector away from the third surface.

Optionally, the third surface on which the polarizing reflector and the first phase retarder are disposed is any one of a plane, a spherical surface, an aspheric surface, a free-form surface, or a cylindrical surface.

Optionally, the angle between the transmission axis of the polarizing reflector and the fast axis or slow axis of the first phase retarder is set to 45°.

Optionally, the light splitter is a semi-reflective and semi-permeable film, and the semi-reflective and semi-permeable film is provided on the first surface.

Optionally, the display unit is a self-luminous screen or a reflective screen.

According to another aspect of the present application, a head-mounted display device is provided. The head-mounted display device includes:

casing; and

According to any one of the above optical modules, the optical module is arranged in the housing.

The beneficial effect of this application is:

The embodiment of the present application proposes a design scheme of a folded optical path structure, which can be applied to electronic devices such as head-mounted display devices. The distance between them can improve the situation that the appearance defect on the lens is magnified to a multiple that is easy to be observed by the human eye through the optical element on the side away from the display unit, otherwise it will cause the appearance defect on the lens to be easily found by the human eye, This further affects the effect of the imaging picture, resulting in poor user experience.

Other features of the present application and advantages thereof will become apparent through the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings.

Description of drawings

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

Fig. 1 is one of the structural schematic diagrams of the optical module provided by the embodiment of the present application;

Fig. 2 is the modulation transfer function MFT curve of the optical module provided by the embodiment of the present application at 450nm;

Fig. 3 is the modulation transfer function MFT curve of the optical module provided by the embodiment of the present application at 540nm;

Fig. 4 is the modulation transfer function MFT curve of the optical module provided by the embodiment of the present application at 610nm;

Fig. 5 is the second structural schematic diagram of the optical module provided by the embodiment of the present application;

Fig. 6 is the third structural schematic diagram of the optical module provided by the embodiment of the present application;

FIG. 7 is a fourth structural schematic view of the optical module provided by the embodiment of the present application.

Explanation of reference signs:

1. Optical axis; 2. Aperture; 3. Second lens; 4. First lens; 5. Protective sheet; 6. Display unit; 7. Light; 8. Polarizing reflector; 9. First phase retarder; 10. Optical splitter; 11. Second phase retarder; 12. Polarizer.

Detailed ways

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 arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and in no way serves as any limitation of the application, its application or uses.

Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the description.

In all examples shown and discussed herein, any specific values should be construed as exemplary only, and not as limitations. Therefore, other instances of the exemplary embodiment may have different values.

It should be noted that like numerals and letters denote like items in the following figures, therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

The optical module and the head-mounted display device provided by the embodiment of the present application will be described in detail below with reference to FIGS. 1 to 7 .

According to an aspect of the embodiments of the present application, an optical module is provided.

The optical module is a folding optical path structure solution, which is suitable for application in electronic equipment, such as head mounted display (HMD), such as VR head mounted equipment (including VR glasses or VR helmets, etc.).

The structure of the optical module provided by the embodiment of the present application is shown in Fig. 1, Fig. 5 to Fig. 7, the optical module includes a display unit 6, and the display unit 6 has a light-emitting surface, and the light-emitting surface can be used for emit incident light;

The optical module includes a first lens 4, which is arranged along the propagation direction of the incident light, and the first lens 4 includes a first surface facing the light-emitting surface and a surface facing away from the light-emitting surface. The second surface, the distance between the first surface and the light-emitting surface is set to ≥1.5mm;

The optical module also includes a polarizing reflector 8, a first phase retarder 9 and a beam splitter 10, the beam splitter 10 is arranged on one side of the first surface, and the polarizing reflector 8 is arranged on the first surface On one side of the two surfaces, the first phase retarder 9 is disposed between the polarizing reflector 8 and the beam splitter 10 .

In the entire optical path structure design of the present application, for the first lens 4, the first surface on it is set as the rear surface of the first lens 4, and the second surface is set as the front surface of the first lens 4 .

In addition, it should be noted that the beam splitter 10 being set on one side of the first surface does not only refer to being set on the first surface, but also can be set between the first surface and the light-emitting surface. A suitable position or a suitable position close to the first surface. Likewise, the polarizing reflector 8 disposed on one side of the second surface does not only refer to being disposed on the second surface, but may also be disposed, for example, at a suitable position close to the second surface.

That is to say, the optical module provided in the embodiment of the present application relates to a design of a folded optical path structure. Wherein, the optical lens near the side of the display unit 6, that is, the first lens 4 is designed to have a relatively large distance, such as ≥1.5mm, from the light-emitting surface of the display unit 6, so that the first lens 4 A defect on the surface or inside of the lens 4 passes through the optical assembly composed of optical elements on the side away from the display unit 6, and the increase in magnification will not be obvious, thereby reducing the amount of defects near the display unit 6 in the folded optical path structure. Side lens appearance defect requirements.

When the distance between the first lens 4 and the light-emitting surface of the display unit 6 is set to <1.5 mm, the defects on the surface or inside of the first lens 4 pass through the optics on the side away from the display unit 6 The magnification of the optical assembly composed of components will increase significantly, which leads to stricter requirements on the appearance defects of the first lens 4 in the optical path structure, which may lead to higher requirements for the manufacturing process of the lens, and may also Increase production cost.

In the optical module provided by the embodiment of the present application, as shown in Fig. 1, Fig. 5 to Fig. 7, in the direction along the optical axis 1, for the first A lens 4, the distance between it and the light-emitting surface of the display unit 6 is set to be ≥ 1.5mm. This can avoid to a certain extent the phenomenon that the magnification increases significantly after the defects on the surface or inside of the first lens 4 pass through the optical assembly composed of the optical elements on the side away from the display unit 6, which is very important for reducing the folded optical path structure. It is favorable for the appearance defect requirement of the lens on the side close to the display unit 6, which in turn helps to simplify the structural design and manufacturing cost of the folded optical path.

Wherein, as shown in FIG. 1 , FIG. 4 to FIG. 7 , the first phase retarder 9 can be used to change the polarization state of the light 7 in the folded optical path structure. For example, it is possible to convert linearly polarized light into circularly polarized light, or convert circularly polarized light into linearly polarized light.

Wherein, the optical components (comprising the polarizing reflector 8, the first phase retarder 9, and the beam splitter 10) on the side away from the display unit 6 can be used to analyze the light 7, for example, the light 7 can be amplified and transmitted .

Wherein, the light emitted by the display unit 6 may be, for example, linearly polarized light or circularly polarized light, or of course natural light.

Embodiments of the present application propose a folded optical path design solution, which can be applied to electronic devices such as head mounted display (HMD).

The optical module provided in the embodiment of the present application can improve the first lens 4 by increasing the distance between the light emitting surface of the display unit 6 and the first lens 4 on the side close to the display unit 6 in the optical path structure. The appearance defect on the first lens 4 is magnified to a multiple that can be easily observed by the human eye through the optical assembly on the side away from the display unit 6, otherwise it will lead to easy discovery of the appearance defect on the first lens 4, and then It affects the effect of the imaging picture, resulting in poor user experience.

That is to say, the optical module provided in the embodiment of the present application is designed as a folded optical path, which reduces the appearance defect requirements of the first lens 4 on the side close to the display unit 6 in the folded optical path structure, and helps to improve The effect of the imaging screen.

In some examples of the present application, the distance between the first surface (rear surface) of the first lens 4 and the light-emitting surface of the display unit 6 is set to T1, and the beam splitter 10 and the polarizing reflector The distance between 8 is set as T2, and the ratio of T1 to T2 is set to 0.1-1.6.

The smaller the above-mentioned ratio value, it indicates that the distance between the first lens 4 and the light-emitting surface of the display unit 6 is smaller, that is, the closer the first lens 4 is to the light-emitting surface of the display unit 6, Then the requirements for the appearance defects of the first lens 4 are higher.

Conversely, the larger the above-mentioned ratio value, the longer the total optical length TTL of the optical module, which is not conducive to the miniaturization design requirements of the entire optical module. Therefore, the above ratio should be reasonably controlled.

That is to say, in the embodiment of the present application, the total optical length TTL of the optical module is comprehensively considered, and the appearance requirements of the first lens 4 (that is, the lens on the side close to the display unit 6) are set. , which is the preferred solution. While ensuring the miniaturization of the folded optical path, the effect of the imaging picture can be guaranteed, and at the same time, the requirements for the appearance defects of the first lens 4 can be reduced.

In some examples of the present application, as shown in FIG. 1, FIG. 5 to FIG. 7, the optical module further includes a protective sheet 5, and the protective sheet 5 is arranged on one side of the light-emitting surface of the display unit 6; wherein , the protection sheet 5 includes a rear surface facing the light-emitting surface and a front surface facing away from the light-emitting surface, and the distance between the rear surface of the protection sheet 5 and the light-emitting surface is set to be ≥ 1 mm.

This design effectively reduces the appearance requirements of the protective sheet 5 and its surface optical film material.

In some examples of the present application, as shown in FIG. 1, FIG. 5 to FIG. 7, the optical module further includes a second phase retarder 11 and a polarizer 12;

Wherein, the polarizer 12 is arranged on one side of the front surface of the protective sheet 5;

The second phase retarder 11 is disposed between the beam splitter 10 and the polarizer 12 .

That is to say, a protective sheet 5 is provided on the light-emitting surface of the display unit 6, and the second phase retarder 11 and the polarizer 12 are both arranged on the side of the protective sheet 5 away from the light-emitting surface. .

For example, when the protective sheet 5 is provided on the light-emitting surface of the display unit 6, both the second phase retarder 11 and the polarizer 12 can be provided on the first lens 4 and the protective sheet 5. between.

In the embodiment of the present application, in order to protect the display unit 6 , the protection sheet 5 is provided on the light-emitting surface (light-emitting surface) of the display unit 6 .

Wherein, the protection sheet 5 can be attached to the light-emitting surface of the display unit 6 by optical glue, for example, and the protection sheet 5 can block the display unit 6 .

The protective sheet 5 is, for example, a glass sheet or a transparent plastic sheet.

It should be noted that those skilled in the art can adjust the material of the protection sheet 5 according to specific requirements, which is not specifically limited in this application.

Wherein, the polarizer 12 and the second phase retarder 11 are designed as a film structure, for example.

On this basis, the polarizer 12 is mounted on the side of the protection sheet 5 facing away from the light-emitting surface, for example, by optical glue, and the second phase retarder 11 is mounted on the side of the protective sheet 5, for example, by optical glue. The polarizer 12 is on the side away from the protective sheet 5 .

In addition, when the display unit 6 directly emits circularly polarized light, the polarizer 12 and the second phase retarder 11 can be eliminated in the optical module.

In some examples of the present application, as shown in FIG. 1, FIG. 5 to FIG. 7, the optical module further includes a second lens 3, and the second lens 3 is arranged on the second On one side of the surface, the second lens 3 and the first lens 4 are located on the same optical axis 1;

The second lens 3 includes a third surface facing the first lens 4 and a fourth surface facing away from the first lens 4;

The polarizing reflector 8 is disposed on one side of the third surface, and the first phase retarder 9 is disposed on a side of the polarizing reflector 8 away from the third surface.

In the optical path structure provided in the embodiment of the present application, the third surface of the second lens 3 is its rear surface, and the fourth surface of the third lens 4 is its front surface.

It should be noted that, in the optical module provided in the embodiment of the present application, including but not limited to only the first lens 4 is provided, more optical lenses and other optical elements may also be provided.

For example, as shown in Fig. 1, Fig. 5 to Fig. 7, an aperture 2 (which can be equivalent to the human eye) is also arranged in the optical module, so that the optical gap between the first lens 4 and the light The second lens 3 is introduced into the optical path between the diaphragms 2, that is, two lenses are arranged in the optical path structure, and then combined with a phase retarder and a polarizing reflector, etc., an imaging lens group located on the side away from the display unit 6 can be formed .

It should be noted that when the second lens 3 is introduced into the optical module, the polarizing reflector 8 and the first phase retarder 9 can be arranged on the third surface of the second lens 3 .

Wherein, the third surface of the second lens 3 faces the second surface of the first lens 4, and the polarizing reflector 8 and the first phase retarder 9 can be connected by the first lens 4 Separated from the beam splitter 10.

When only the first lens 4 is arranged in the optical module, the polarizing reflector 8 and the first phase retarder 9 can be arranged on the side of the first lens 4 away from the display unit 6 One side, that is, the second surface (front surface), and the beam splitter 10 is arranged on the side of the first lens 4 facing the display unit 6, that is, the first surface (rear surface) superior.

In the optical module provided in the embodiment of the present application, the number of lenses can be one, two or three, or even more, and those skilled in the art can flexibly adjust according to specific needs, and this application does not make specific limitations here .

In some examples of the present application, the third surface on which the polarizing reflector 8 and the first phase retarder 9 are disposed is any one of a plane, a spherical surface, an aspheric surface, a free-form surface or a cylindrical surface.

That is to say, the polarizing reflector 8 and the first phase retarder 9 can be arranged on various surface optical elements (such as lenses), so that the polarizing reflector 8 and the first phase retardation The device 9 can effectively adapt to the position of the mounting surface.

In some examples of the present application, the polarizer 12 is a linear polarizer.

Wherein, the polarizer 12 is a linear polarizer, which has a transmission axis through which light passes, and the direction of the transmission axis can be along the horizontal direction, the vertical direction or any other direction. The incident light emitted by the light emitting surface of the display unit 6 can be converted into linearly polarized light when passing through the polarizer 12 .

The polarizer 12 is, for example, designed as a film structure, which can be attached to the light emitting surface of the display unit 6 by optical adhesive. When the protective sheet 5 is provided on the light-emitting surface of the display unit 6 , the polarizer 12 can be attached to the protective sheet 5 away from the light-emitting surface through optical adhesive.

In some examples of the present application, at least one of the first phase retarder 9 and the second phase retarder 11 is a quarter-wave plate.

For example, the first phase retarder 9 and the second phase retarder 11 are the same, and both are quarter wave plates. Quarter wave plates can be used to convert linearly polarized light to circularly polarized light, and circularly polarized light to linearly polarized light.

In the embodiment of the present application, the second phase retarder 11 on the side close to the display unit 6 is located between the polarizer 12 and the beam splitter 10, and all the second phase retarders on the side away from the display unit 6 The first phase retarder 9 is located between the beam splitter 10 and the polarizing reflector 8 . As shown in FIG. 1 , FIG. 5 to FIG. 7 , when the light 7 passes through each quarter-wave plate, the light 7 can be converted from a circular polarization state to a linear polarization state.

For example, both the first phase retarder 9 and the second phase retarder 11 may be independent optical devices, and of course both may be film-layer structures.

When the first phase retarder 9 and the second phase retarder 11 are independent optical devices, they can be fixed in the optical path structure by other components, such as lens barrels and the like. For example, the inner wall of the lens barrel is provided with a slot, and the corresponding phase retarder can be snapped into the slot.

When both the first phase retarder 9 and the second phase retarder 11 have a film structure, they can be directly attached to corresponding optical elements.

Those skilled in the art can flexibly adjust the arrangement of the first phase retarder 9 and the second phase retarder 11 in the optical path structure according to needs, which will not be described in detail in this application.

In some examples of the present application, the polarizer 12 has a transmission axis through which light passes, and the included angle between the transmission axis of the polarizer 12 and the fast axis of the second phase retarder 11 is set as 45°, the angle between the transmission axis of the polarizer 12 and the slow axis of the second phase retarder 11 is set to negative 45°.

Wherein, the second phase retarder 11 and the polarizer 12 are sequentially arranged along the propagation direction of the light emitted by the light-emitting surface of the display unit 6, the polarizer 12 has a transmission axis, and the polarizer 12 The included angle between the transmission axis and the fast axis of the second phase retarder 11 is 45°; the included angle can be positive 45° or negative 45°.

The second phase retarder 11 has a fast axis and a slow axis. Wherein, the direction of the transmission axis of the linear polarizer 12 can pass through the polarizer 12 , while the direction of the transmission axis of the polarizer 12 can not pass through the polarizer 12 .

In some examples of the present application, the angle between the transmission axis of the polarizing reflector 8 and the fast axis of the first phase retarder 9 is set to 45°, and the transmission axis of the polarizing reflector 8 The included angle with the slow axis of the first phase retarder 9 is set to negative 45°.

Wherein, the polarizing reflector 8 is a kind of polarizing reflector that reflects horizontally linearly polarized light and transmits vertically linearly polarized light, or reflects linearly polarized light at any specific angle, and transmits linearly polarized light perpendicular to the angle. polarizing reflector.

Wherein, the polarizing reflector 8 may be an independent optical device, or may be a film structure.

In some examples of the present application, the beam splitter 10 is a semi-reflective and semi-permeable film, and the semi-reflective and semi-permeable film is, for example, provided on the first surface (rear surface) of the first lens 4 .

As shown in Fig. 1, Fig. 5 to Fig. 7, the semi-reflective and semi-permeable film can ensure that part of the light passes through and part of the light is reflected.

The transflective film is, for example, attached to the first surface (rear surface) of the first lens 4 .

The beam splitter 10 can be set as an independent optical device set in the optical path structure, or it can be set as a film layer structure attached to the first surface of the first lens 4, those skilled in the art can flexibly according to specific needs selection, the present application does not make specific limitations here.

In some examples of the present application, the display unit 6 is a self-illuminating screen or a reflective screen.

The light emitted by the display unit 6 may be, for example, linearly polarized light, or circularly polarized light, or of course natural light.

Wherein, the self-luminous screen includes but not limited to LCD (Liquid Crystal Display), LED (Light Emitting Diode), OLED (Organic Light-Emitting Diode), Micro-OLED (Micro-Organic Light-Emitting Diode), ULED ( UltraLightEmitting Diode), etc.

Wherein, the reflective screen includes but not limited to DMD (Digital Micromirror Device) digital micromirror chip.

The working principle of the optical module provided by the embodiment of the present application will be described below with reference to FIG. 1 .

The optical module includes: an optical axis 1, a diaphragm 2, a second lens 3, a first lens 4, a protective sheet 5, a display unit 6 (with a light-emitting surface capable of emitting incident light), a polarizing reflector 8, a first Phase retarder 9, beam splitter 10, second phase retarder 11 and polarizer 12; Wherein, each optical element is all positioned on optical axis 1, described first lens 4, described second lens 3 and described diaphragm 2 arranged in sequence along the light propagation direction, the first lens 4 includes a first surface facing the light-emitting surface and a second surface away from the light-emitting surface, the distance between the first surface and the light-emitting surface set to ≥1.5mm; the second lens 3 includes a third surface facing the first lens 4 and a fourth surface facing the diaphragm 2; the beam splitter 10 is arranged on one of the first surfaces side, the polarizing reflector 8 is arranged on one side of the third surface, and the first phase retarder 9 is arranged on the side of the polarizing reflector 8 away from the third surface, so that the first A phase retarder 9 is located between the polarizing reflector 8 and the beam splitter 10, the polarizer 12 is arranged on one side of the light-emitting surface, and the second phase retarder 11 is arranged on the beam splitter 10 and the polarizer 12;

Wherein, the distance between the first surface of the first lens 4 and the light-emitting surface of the display unit 6 is set to T1, the distance between the beam splitter 10 and the polarizing reflector 8 is set to T2, and The ratio of the T1 to the T2 is set to 0.1-1.6;

Wherein, the protection sheet 5 is arranged on one side of the light-emitting surface of the display unit 6;

Wherein, the polarizer 12 is a linear polarizer, the first phase retarder 9 and the second phase retarder 11 are both quarter-wave plates; the polarizing reflector 8 is a horizontal linearly polarized light Reflector, a polarizing reflector through which vertically linearly polarized light passes.

The light 7 emitted from the light-emitting surface of the display unit 6 becomes horizontal linearly polarized light after passing through the protective sheet 5 and the polarizer 12, and becomes left-handed or right-handed circularly polarized light after passing through the second phase retarder 11. Light, after passing through the beam splitter 10 and the first lens 4, then passes through the first phase retarder 9, becomes horizontally linearly polarized light, and then becomes horizontally linearly polarized after being reflected by the polarizing reflector 8 The light becomes left-handed or right-handed circularly polarized light after passing through the first phase retarder 9 and the first lens 4, and then becomes right-handed or left-handed circularly polarized light after being reflected by the beam splitter 10, again After passing through the first lens 4 and the first phase retarder 9, it becomes vertically linearly polarized light, and after passing through the second lens 3, it can enter the diaphragm 2 (human eye) for imaging .

Wherein, the first lens 4 is the lens near the side of the display unit 6. When it is closer to the light-emitting surface of the display unit 6, the surface or internal defects of the first lens 4 are far away from the display unit 6. The greater the rear magnification of the optical components on the side of unit 6, the easier it is to be observed by the human eye. Therefore, the closer the first lens 4 is to the light-emitting surface of the display unit 6 , the higher the requirement for its appearance.

In the optical module provided by the embodiment of the present application, by increasing the distance between the first lens 4 on the side near the display unit 6 in the optical path structure and the light-emitting surface of the display unit 6, the lens size is reduced. The magnification of surface and internal defects on the imaging of the optical components on the side away from the display unit 6 effectively reduces the requirements for the appearance defects of the lens near the display unit 6 in the folded optical path structure, and also helps to improve the imaging picture Effect.

Example 1

As shown in FIG. 1, the optical module includes a display unit 6, the display unit 6 has a light-emitting surface, and the light-emitting surface can be used to emit incident light;

The optical module includes a first lens 4, a second lens 3, and an aperture 2, and the first lens 4, the second lens 3, and the aperture 2 are sequentially arranged along the propagation direction of light and are located on the same optical axis 1 On; the first lens 4 includes a first surface (rear surface) facing the light-emitting surface and a second surface (front surface) away from the light-emitting surface, the distance between the first surface and the light-emitting surface The distance T1 is set to 4.5 mm; the second lens 3 includes a third surface (rear surface) facing the first lens 4 and a fourth surface (front surface) facing the diaphragm 2;

The optical module also includes a polarizing reflector 8, a first phase retarder 9, a beam splitter 10, a second phase retarder 11, and a polarizer 12; the beam splitter 10 is arranged on one side of the first surface, The polarizing reflector 8 is arranged on one side of the third surface, and the first phase retarder 9 is arranged on the side of the polarizing reflector 8 away from the third surface, so that the first phase The retarder 9 is located between the polarizing reflector 8 and the beam splitter 10, the polarizer 12 is arranged on one side of the light-emitting surface, and the second phase retarder 11 is arranged between the beam splitter 10 and the beam splitter 10. between the polarizers 12.

Table 1 shows specific parameters of the optical module provided in Embodiment 1.

Table 1 Structural parameter table of the optical module of embodiment 1

FIG. 2 , FIG. 3 and FIG. 4 respectively show the modulation transfer function MTF curves of the optical module provided by the embodiment of the present application at 450 nm, 540 nm, and 610 nm. It can be seen from Figure 2-Figure 4: at 70lp/mm spatial frequency:

At 450nm wavelength, the MTF value of the optical module is higher than 0.75;

At 540nm wavelength, the MTF value of the optical module is higher than 0.7;

At 610nm wavelength, the MTF of the optical module is higher than 0.65.

According to Table 1, the distance T1 between the first surface (rear surface) of the first lens 4 and the light-emitting surface of the display unit 6 is set to 4.5mm, and the beam splitter 10 and the polarizing reflector The distance T2 between 8 is set to 10.16mm, and the ratio of T1 to T2 is 0.44.

Example 2

Table 2 shows the structural parameters of the optical module provided by Embodiment 2, and FIG. 5 shows the structure of the optical module, and its difference from Embodiment 1 is:

In embodiment 2, the specific setting between the rear surface of the protective sheet 5 and the light-emitting surface of the display unit 6 is 3.5mm, which is in line with the aforementioned light-emitting surface between the rear surface of the protective sheet 5 and the display unit. The distance between the faces is greater than the setting of 1mm.

And, in embodiment 2, the value of the distance T1 between the first surface (rear surface) of the first lens 4 and the light emitting surface of the display unit 6 is 4.5 mm, and the beam splitter 10 and the polarizer The distance T2 between the reflectors 8 is 10.16, and the ratio of T1 to T2 is 0.44.

Table 2 Structural parameter table of the optical module of embodiment 2

Example 3

In Embodiment 3, the value of the distance T1 between the first surface (rear surface) of the first lens 4 and the light emitting surface of the display unit 6 is adjusted. Table 3 shows the specific structural parameters of the optical module provided by Embodiment 3.

Specifically, referring to Table 3, the distance T1 between the first surface and the light-emitting surface is set to 1.5mm, and the distance T2 between the beam splitter 10 and the polarizing reflector 8 is set to 15.36mm , then the ratio of T1 to T2 is 0.1.

The structural parameter table of the optical module of table 3 embodiment 3

Example 4

Table 4 shows specific structural parameters of the optical module of Example 4, and FIG. 6 shows a schematic structural view of the optical module. In the optical module design of embodiment 4:

Specifically, referring to Table 4, the distance T1 between the first surface of the first lens 4 and the light-emitting surface of the display unit 6 is set to 2.36mm, and the beam splitter 10 and the polarizing reflector 8 The distance T2 between them is set to be 14.66mm, on this basis, the ratio of T1 to T2 is 0.16.

Table 4 Structural parameter list

Example 5

Table 5 shows specific structural parameters of the optical module of Example 5, and FIG. 7 shows a schematic structural view of the optical module.

In the optical module design of embodiment 5:

Specifically, referring to Table 5, the distance T1 between the first surface of the first lens 4 and the light-emitting surface of the display unit 6 is set to 11.66 mm; the beam splitter 10 and the polarizing reflector 8 The distance T2 between them is set to 7.26 mm, on this basis, the ratio of T1 to T2 is 1.6, which is the upper limit of the ratio of the two.

Table 5 shows the structural parameters of the optical module of Example 5.

Table 5 Structural parameter table of the optical module of embodiment 5

According to another aspect of the present application, a head-mounted display device is provided.

The head-mounted display device includes a casing and the above optical module, and the optical module is arranged on the casing.

Wherein, the housing can provide an installation space for supporting the optical module, and the optical module is arranged in the housing, so as to prevent water vapor or dust from the external environment from falling into the optical module.

The head-mounted display device is, for example, a VR device.

The above-mentioned embodiments focus on the differences between the various embodiments. As long as the different optimization features of the various embodiments do not contradict each other, they can be combined to form a better embodiment. Considering the brevity of the text, no further repeat.

Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, rather than limiting the scope of the present application. Those skilled in the art will appreciate that modifications can be made to the above embodiments without departing from the scope and spirit of the application. The scope of the application is defined by the appended claims.

Claims

An optical module, characterized in that it comprises:

a display unit (6), the display unit (6) has a light-emitting surface, and the light-emitting surface is used to emit incident light;

The first lens (4), the first lens (4) is arranged along the propagating direction of the incident light, the first lens (4) includes a first surface facing the light emitting surface and a surface facing away from the light emitting surface The second surface, the distance between the first surface and the light-emitting surface is set to ≥1.5mm;

The optical module also includes a polarizing reflector (8), a first phase retarder (9) and a beam splitter (10), the beam splitter (10) is arranged on one side of the first surface, and the polarizing A reflector (8) is arranged on one side of the second surface, and the first phase retarder (9) is arranged between the polarizing reflector (8) and the beam splitter (10).
The optical module according to claim 1, wherein the distance between the first surface of the first lens (4) and the light-emitting surface of the display unit (6) is set to T1, and the beam splitter The distance between (10) and the polarizing reflector (8) is set to T2, and the ratio of T1 to T2 is set to 0.1-1.6.
The optical module according to claim 1, characterized in that the optical module further comprises a protective sheet (5), and the protective sheet (5) is arranged on one side of the light-emitting surface of the display unit (6);

The protection sheet (5) includes a rear surface facing the light-emitting surface and a front surface facing away from the light-emitting surface, and the distance between the rear surface of the protection sheet (5) and the light-emitting surface is set to be ≥ 1mm.
The optical module according to claim 3, wherein the optical module further comprises a second phase retarder (11) and a polarizer (12);

The polarizer (12) is arranged on one side of the front surface of the protective sheet (5);

The second phase retarder (11) is arranged between the beam splitter (10) and the polarizer (12).
The optical module according to claim 4, characterized in that the polarizer (12) is a linear polarizer.
The optical module according to claim 4, wherein the polarizer (12) has a transmission axis through which light passes, and the transmission axis of the polarizer (12) is connected to the second phase retarder The included angle between the fast axis or the slow axis of (11) is set to 45°.
The optical module according to claim 4, characterized in that at least one of the first phase retarder (9) and the second phase retarder (11) is a quarter-wave plate.
The optical module according to claim 1, characterized in that, the optical module further comprises a second lens (3), and the second lens (3) is arranged on the second side of the first lens (4). On one side of the surface, the second lens (3) and the first lens (4) are located on the same optical axis (1);

The second lens (3) includes a third surface facing the first lens (4) and a fourth surface facing away from the first lens (4);

The polarizing reflector (8) is arranged on one side of the third surface, and the first phase retarder (9) is arranged on the side of the polarizing reflector (8) away from the third surface.
The optical module according to claim 8, characterized in that, the third surface on which the polarizing reflector (8) and the first phase retarder (9) are located is a plane, a spherical surface, an aspheric surface, Either free-form surface or cylindrical surface.
The optical module according to claim 1, characterized in that the angle between the transmission axis of the polarizing reflector (8) and the fast axis or slow axis of the first phase retarder (9) is set is 45°.
The optical module according to claim 1, wherein the beam splitter (10) is a semi-reflective and semi-permeable film, and the semi-reflective and semi-permeable film is arranged on the first surface.
The optical module according to claim 1, characterized in that the display unit (6) is a self-luminous screen or a reflective screen.
A head-mounted display device, characterized in that: comprising:

casing; and

The optical module according to any one of claims 1-12, wherein the optical module is arranged in the casing.