WO2023273128A1

WO2023273128A1 - Optical module and head-mounted display apparatus

Info

Publication number: WO2023273128A1
Application number: PCT/CN2021/133329
Authority: WO
Inventors: 孙琦
Original assignee: 歌尔光学科技有限公司
Priority date: 2021-06-28
Filing date: 2021-11-26
Publication date: 2023-01-05
Also published as: CN113448100A

Abstract

An optical module and a head-mounted display apparatus. The optical module comprises: a display (10), a cemented lens (20), a beam splitter (30), a quarter-wave plate (40) and a polarizing and reflecting film (50), wherein the display (10) emits light rays (110) for imaging display; the cemented lens (20) is arranged in a light-emergent direction of the display (10), and the cemented lens (20) comprises a first lens (210) and a second lens (220), the first lens (210) and the second lens (220) being sequentially arranged in a propagation direction of an optical path, a second surface (212) of the first lens (210) being cemented to a third surface (221) of the second lens (220), the third surface (221) being convex in the direction of the display (10), and a fourth surface (222) of the second lens (220) being convex in a direction away from the display (10); the beam splitter (30) is arranged on a first surface (211) of the first lens (210); the quarter-wave plate (40) is arranged between the first lens (210) and the second lens (220); and the polarizing and reflecting film (50) is arranged between the quarter-wave plate (40) and the second lens (220). Therefore, the total optical length of an optical system can be reduced, and the size of the head-mounted display apparatus can also be reduced, thereby being conducive to being worn by a user.

Description

Optical modules and head-mounted display devices

technical field

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

Background technique

With the development and upgrading of advanced optical design and processing technology, display technology and processor, the forms and types of virtual reality (VR) products emerge in an endless stream, and its application fields are becoming more and more extensive. The main working principle of virtual reality products is that after the image displayed on the display is transmitted and magnified by optical lenses, the image is received by the human eye, and what the human eye observes is a magnified virtual image. After the image is enlarged, a sufficiently long optical path is required, so the total optical length of the optical system is longer, resulting in a larger volume of the head-mounted display device, which is not convenient for the user to wear.

Contents of the invention

Based on this, in order to solve the problems that the optical system of the existing head-mounted display device has a long optical length, the head-mounted display device is large in size, and is not convenient for users to wear, it is necessary to provide an optical module and a head-mounted display device, which aim at The overall optical length of the optical system can be reduced, the volume of the head-mounted display device can be reduced, and it is convenient for users to wear it.

In order to achieve the above object, the present invention proposes an optical module, the optical module includes:

a display that emits light for an imaged display;

A cemented lens, the cemented lens is arranged in the light emitting direction of the display, the cemented lens includes a first lens and a second lens, the first lens and the second lens are arranged in sequence along the propagation direction of the optical path, the The first lens has a first surface facing the display and a second surface facing away from the display, the second lens has a third surface facing the display and a fourth surface facing away from the display, the The second surface is glued to the third surface, the third surface is raised toward the direction of the display, and the fourth surface is raised toward the direction away from the display;

a beam splitter, the beam splitter is disposed on the first surface;

a quarter wave plate disposed between the first lens and the second lens; and

a polarized reflective film, the polarized reflective film is arranged between the quarter wave plate and the second lens;

Defining the field curvature of the optical module as fv, it satisfies: 0.3mm<fv<0.8mm.

Optionally, define the pixel size of the display as P, and the spot diameter of the full field of view of the optical module as D, then satisfy: D<P.

Optionally, the structure of the second surface is the same as that of the third surface.

Optionally, the first surface is convex toward the direction of the display.

Optionally, the optical module further includes a polarizing film, and the polarizing film is disposed on a side of the first lens away from the display.

Optionally, the polarizing film is disposed between the polarizing reflective film and the second lens, and the quarter wave plate, the polarizing reflective film and the polarizing film are combined into an integral film layer.

Optionally, the optical module further includes an anti-reflection film, and the anti-reflection film is provided on the fourth surface.

Optionally, the central thickness of the first lens is T1, the central thickness of the second lens is T2, and the distance between the first surface and the light-emitting surface of the display is L, then:

4mm<T1<8mm, 3mm<T2<7mm, 10mm<L<15mm.

Optionally, the radius value of the first surface is R1, the conic coefficient of the first surface is C1, the radius value of the second surface is R2, the conical coefficient of the second surface is C2, and the The radius value of the fourth surface is R4, and the conic coefficient of the fourth surface is C4, which satisfies:

40mm<R1<60mm, C1<5;

70mm<R2<100mm, C2≤5;

150mm<R4<200mm, C4≤10.

In addition, in order to solve the above problems, the present invention also provides a head-mounted display device, the head-mounted display device includes a casing and an optical module as described above, the optical module is arranged in the casing, the The total optical length of the optical module is TTL, which satisfies:

TTL<25mm.

In the technical solution proposed by the present invention, the display emits light, and the emitted light is circularly polarized light. When light hits the cemented lens, the light first passes through the beam splitter, one part of the light is transmitted through the beam splitter, and the other part of the light is reflected. The light transmitted through the beam splitter continues to the quarter-wave plate, the polarization state of the circularly polarized light changes, and the circularly polarized light is transformed into linearly polarized light. The linearly polarized light is directed towards the polarized reflective film, at this time, the vibration direction of the linearly polarized light is different from the transmission direction of the polarized reflective film, and the light is reflected. The reflected light passes through the quarter-wave plate and the beam splitter in turn, and when the light passes through the beam splitter again, the light is partially reflected to the cemented lens. At this time, the light is circularly polarized light. After reflection, the direction of rotation of the light changes, and the light is converted into linearly polarized light after passing through a quarter-wave plate again. At this time, the polarization direction of the linearly polarized light is the same as that of the polarized reflective film The transmission direction of the lens is the same, and the light passes through the glued lens group and forms an image at the position of the human eye. It can be seen that when the light passes through the cemented lens, the light is refracted and reflected. In this process, the light is continuously enlarged and transmitted. The enlarged transmission of the image is realized in a limited space, which is beneficial to reduce the total optical length. In addition, the fourth surface of the second lens is convex in a direction away from the display. In this way, light rays can be converged, further reducing the total optical length of the entire system, which is beneficial to reducing the volume of the head-mounted display device and is convenient for users to wear. Moreover, through the protrusion on the third surface, a means for adjusting the imaging performance of the optical module is added. Furthermore, the field curvature fv of the optical module is less than 0.8mm and greater than 0.3mm, which shows that the field curvature of the optical module is small and the imaging quality is high.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative effort.

FIG. 1 is a schematic structural view of an embodiment of an optical module of the present invention;

Fig. 2 is a schematic structural view of the first lens and the second lens of the optical module in Fig. 1;

Fig. 3 is a schematic structural view of a quarter-wave plate, a polarizing reflective film and a polarizing film in another embodiment of the optical module of the present invention;

Fig. 4 is a field curvature and distortion diagram of the optical module in Fig. 1;

Fig. 5 is a chromatic aberration diagram of the optical module in Fig. 1;

FIG. 6 is a spot diagram of the optical module in FIG. 1 .

Explanation of reference numbers:

标号label	名称 name	标号label		名称name
1010	显示器 monitor	221221	第三表面 third surface
110110	光线the light	222222	第四表面 fourth surface
2020	胶合透镜cemented lens	3030	分光件 Splitter
210210	第一透镜 first lens	4040	四分之一波片 quarter wave plate
211211	第一表面 first surface	5050	偏振反射膜polarized reflective film
212212	第二表面 second surface	6060	偏光膜polarizing film
220220	第二透镜 second lens	7070	人眼human eye

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

detailed description

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

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

In addition, in the present invention, descriptions such as "first", "second" and so on are used for description purposes only, and should not be understood as indicating or implying their relative importance or implicitly indicating the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless specifically defined otherwise.

In the present invention, unless otherwise specified and limited, the terms "connection" and "fixation" should be understood in a broad sense, for example, "fixation" can be a fixed connection, a detachable connection, or an integral body; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be an internal communication between two elements or an interaction relationship between two elements, unless otherwise clearly defined. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In addition, the technical solutions of the various embodiments of the present invention can be combined with each other, but it must be based on the realization of those skilled in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered as a combination of technical solutions. Does not exist, nor is it within the scope of protection required by the present invention.

The display principles of head-mounted display devices also include a variety of display principles. For example, in addition to VR display, it also includes AR (Augmented Reality, Augmented Reality) display. The images displayed by these head-mounted display devices need to be transmitted and magnified by optical lenses. , in the process of image enlargement, enough space is needed for light transmission, and the total optical length of the optical system is relatively long, resulting in a large volume of the head-mounted display device, which is inconvenient for users to wear.

In order to solve the above problems, referring to Fig. 1 to Fig. 3, the present invention provides an optical module, the optical module includes: a display 10, a cemented lens 20, a beam splitter 30, a quarter wave plate 40 and a polarized reflection film 50. Wherein, the beam splitter 30 , the quarter wave plate 40 and the polarizing reflection film 50 are arranged in sequence along the propagation direction of the light 110 .

The display 10 emits light 110 for imaging display; the emitted light 110 is circularly polarized light, and when the light 110 emitted by the display 10 is linearly polarized light, a quarter-wave plate can be arranged on the light-emitting surface of the display 10 to linearly polarize the light After passing through a quarter-wave plate, it is converted into circularly polarized light.

The cemented lens 20 is arranged in the light-emitting direction of the display 10. The cemented lens 20 includes a first lens 210 and a second lens 220. It can be understood that the first lens 210 and the second lens 220 are cemented. The method can reduce the overall volume of the optical module. In addition, through the glued arrangement of the first lens 210 and the second lens 220 , the two lenses form an integral structure, and when assembling the optical module, the installation of the two lenses can be completed by one placement. Specifically, the first lens 210 and the second lens 220 are arranged in sequence along the propagation direction of the optical path, the first lens 210 has a first surface 211 facing the display 10 and a second surface 212 facing away from the display 10, and the second lens 220 has a surface facing The third surface 221 of the display 10 and the fourth surface 222 facing away from the display 10, the second surface 212 and the third surface 221 are glued together, and the fourth surface 222 protrudes toward the direction away from the display 10; the human eye 70 is on the fourth surface 222 on the side facing away from the display 10 . After passing through the fourth surface 222 , the light 110 forms an image at the position of the human eye 70 . Through the protrusion of the fourth surface 222 , the light 110 converges toward the position of the human eye 70 after passing through the fourth surface 222 . The convergence of the light rays 110 can further reduce the total optical length, and is also beneficial to the miniaturization of the optical module. In order to further improve the imaging quality, the third surface 221 protrudes toward the direction of the display 10 . Through the convex setting of the third surface 221, a new degree of freedom for adjusting the optical design is added, which can also be understood as adding an adjustable means, and the third surface 221 can be flexibly matched with the first surface 211 and the fourth surface 222. For example, the third surface 221 may be set as an aspheric surface or a free-form surface, etc., and aberrations may be reduced through the aspherical surface or the free-form surface. In addition, through the convex setting of the third surface 221, it can be seen that the second lens 220 forms a biconvex lens with double convexity, and the focusing and imaging position of the light 110 can be further shortened by the biconvex lens, reducing the total optical length of the entire system.

The light splitting element 30 is disposed on the first surface 211 ; the function of the light splitting element 30 is to split light, to partially reflect and partially transmit the incident light 110 , such as a semi-reflective and semi-transparent film. Or the light 110 in one state is transmitted, and the light 110 in another state is reflected, such as the polarized reflective film 50 . The light splitter 30 can be independently arranged between the display 10 and the double-lens lens group, or it can be arranged on the first surface 211 of the first lens 210 . For example, optical glue is disposed between the light splitting element 30 and the first surface 211 , and the light splitting element 30 is pasted on the first surface 211 through the optical glue. It can also be arranged on the first surface 211 by means of coating.

The quarter-wave plate 40 is disposed between the first lens 210 and the second lens 220; the quarter-wave plate 40 is used to convert the polarization state of the light 110, for example, converting linearly polarized light into circularly polarized light, or To convert circularly polarized light into linearly polarized light, the polarization state of the light 110 will change every time the light 110 passes through the quarter-wave plate 40 . The polarizing reflection film 50 is disposed between the quarter wave plate 40 and the second lens 220 . The polarized reflective film 50 has a polarized transmission direction, which can also be understood as a transmission axis. For example, if the transmission axis extends horizontally, the light 110 emitted by the display 10 is circularly polarized light, and the circularly polarized light is converted into linearly polarized light after passing through the quarter-wave plate 40, and the vibration direction of the linearly polarized light is the same as that of the transmission axis. , then light 110 passes through. If the vibration direction of the linearly polarized light is different from the transmission axis, the light ray 110 is reflected. In order to ensure the reflective effect of the polarized reflective film 50 , the vibration direction of the linearly polarized light is perpendicular to the extending direction of the transmission axis. The field curvature of the optical module is defined as fv, which satisfies: 0.3mm<fv<0.8mm. As an example again, referring to Fig. 4 and Fig. 5, for example, when the third surface 221 is a plane, the curvature of field is 1.2mm, if the third surface 221 is set as a convex surface, the curvature of field is 0.5mm, and the 58%. Of course, it should be pointed out that the smaller the field curvature, the higher the imaging quality. For example, field curvature can also be 0.4mm or 0.6mm. It can be seen that by increasing the convexity of the third surface 221, the imaging effect and clarity can be effectively improved, so that the optical module can match the display 10 with higher resolution, and the improvement of the field curvature can make the screen from the center to the edge. The image quality becomes clearer, making the user experience better.

In the technical solution proposed in this embodiment, the display 10 emits light 110, and the emitted light 110 is circularly polarized light. When the light 110 is incident on the cemented lens 20 , the light 110 first passes through the beam splitter 30 , a part of the light 110 is transmitted through the beam splitter 30 , and the other part of the light 110 is reflected. The light 110 transmitted through the beam splitter 30 continues toward the quarter-wave plate 40 , the polarization state of the circularly polarized light 110 changes, and the circularly polarized light is transformed into linearly polarized light. The linearly polarized light 110 is directed toward the polarizing reflective film 50 . At this time, the vibration direction of the linearly polarized light is different from the transmission direction of the polarizing reflective film 50 , and the light 110 is reflected. The reflected light 110 sequentially passes through the quarter-wave plate 40 and the beam splitter 30 , and when the light 110 passes through the beam splitter 30 again, the light 110 is partially reflected to the cemented lens 20 . At this time, the light 110 is circularly polarized light. After reflection, the direction of rotation of the light 110 changes, and the light 110 passes through the quarter-wave plate 40 again and is converted into linearly polarized light again. At this time, the polarization direction of the linearly polarized light The same as the transmission direction of the polarized reflection film 50 , the light 110 passes through the doubled lens group and forms an image at the position of the human eye 70 . It can be seen that, when the light 110 passes through the cemented lens 20 , the light 110 is refracted and reflected, and during this process, the light 110 is continuously enlarged and transmitted. The magnified transmission of the image is realized in a limited space, which is beneficial to reduce the total optical length. In addition, the fourth surface 222 of the second lens 220 protrudes away from the direction of the display 10 . In this way, the light rays 110 can be converged, further reducing the total optical length of the entire system, which is beneficial to reducing the volume of the head-mounted display device and is convenient for users to wear. Moreover, through the protrusion on the third surface, a means for adjusting the imaging performance of the optical module is added. Furthermore, the field curvature fv of the optical module is less than 0.8mm and greater than 0.3mm, which shows that the field curvature of the optical module is small and the imaging quality is high. It should be pointed out that the curvature of field includes the meridian direction and the sagittal direction, and the field curvature in the two directions is close to or equal, and the field curvature in the two directions is between 0.3 mm and 0.8 mm.

Further, through the cemented arrangement of the first lens 210 and the second lens 220 , the light 110 can reduce passing through air when passing through the cemented lens group, thereby reducing ghost images and stray light formed by passing through media with different refractive indices.

The first lens 210 and the second lens 220 can be made of optical glass, which can ensure the imaging quality. Furthermore, in order to reduce weight and reduce processing costs, the first lens 210 and the second lens 220 can be manufactured by optical plastic processing. For example, the first lens 210 is a COC (Cycloalkene Copolymer) cycloolefin copolymer material, and the second lens 220 is a COP (Cyclo Olefin Polymer) cycloolefin polymer material, wherein the light 110 is refracted and reflected in the first lens 210, and the COC The material can withstand relatively high stress, and the light 110 directly transmits through the second lens 220 , so the COP material has a relatively low stress requirement. In addition, the first lens 210 and the second lens 220 can also choose materials such as OKP or PMMA (methylmethacrylate).

Referring to Figure 6, define the pixel size of the display as P, and the spot diameter of the full field of view of the optical module as D, then satisfy: D<P. Simply put, the spot diameter of the full field of view is less than 1 times the pixel size. Likewise, the smaller the spot diameter, the higher the imaging quality. For example, the pixel size P is 24um. If the third surface 221 is flat, the spot diameter is 47.5um. If the third surface 221 is convex, the spot diameter is 17.6um, and the imaging quality is improved by 60%. In addition, the spot diameter can also be 15um, 20.0um, 25.0um, etc. Or other values smaller than 24um. Of course, it should be pointed out that the size of the spot diameter varies with the pixel size, as long as the spot diameter of the full field of view is less than 1 times the pixel size, it is within the scope of protection of this solution.

Further, in order to improve the adhesion between the first lens 210 and the second lens 220, the structure of the second surface 212 and the third surface 221 is the same, so that when the first lens 210 and the second lens 220 are glued together, the two lenses Gaps can be reduced. In turn, impurities such as dust can be prevented from falling between the two lenses.

In one embodiment, in order to further shorten the total optical length, the first surface 211 protrudes toward the direction of the display 10 . It can be seen that, through the protrusions on the first surface 211 and the protrusions on the fourth surface 222 , the cemented lens 20 as a whole can form the effect of a biconvex lens. Therefore, the focusing and imaging position of the light 110 can be further shortened, and the total optical length of the entire system can be reduced. It should be noted that if the third surface 221 of the second lens 220 is a convex surface, then the second surface 212 of the first lens 210 is a concave surface. On the basis that the first surface 211 is a convex surface, it can be seen that the first The lens 210 is a meniscus lens.

In the above embodiment, during the propagation of the light 110, the vibration direction of part of the linearly polarized light may form an included angle with the transmission direction of the polarized reflection film 50, and the included angle ranges from 0° to 90°, that is to say, partly The vibration direction of the linearly polarized light is neither the same as the transmission direction of the polarizing reflection film 50 nor perpendicular to it. In this way, stray light will appear after the light 110 passes through the polarizing reflective film 50 . In order to reduce the stray light, the optical module further includes a polarizing film 60 . The polarizing film 60 is disposed on the side of the first lens 210 facing away from the display 10 . The polarizing film 60 has a transmission direction, and the transmission direction of the polarizing film 60 is the same as that of the polarizing reflection film 50 . The polarizing film 60 filters out the passing light 110 , and the light 110 in a direction different from the transmission direction will be filtered and absorbed, so as to ensure that the light 110 passing through the optical module can maintain a consistent vibration direction and reduce the appearance of stray light.

In addition, the light passing through the polarizing film 60 is linearly polarized light, and when the human eye 70 observes the linearly polarized light, the quality of the imaging effect is poor. In this way, a quarter-wave plate can be installed between the second lens 220 and the polarizing film 60 to convert linearly polarized light into circularly polarized light, ensuring that the light received by the human eye 70 is circularly polarized, thereby improving imaging quality.

Further, in order to reduce the total optical length, the polarizing film 60 is arranged between the polarizing reflective film 50 and the second lens 220, and the quarter wave plate 40, the polarizing reflective film 50 and the polarizing film 60 are combined into an integral film layer. Through an overall film layer structure, the thickness of the film layer can be compressed and the optical adhesive layer between each film layer can be reduced. At the same time, the installation of three film layers can be completed through the application of one whole film layer. When pasting the overall film layer, an optical adhesive layer is provided on the surface of the quarter-wave plate 40 facing the first lens 210 and the surface of the polarizing film 60 facing the second lens 220, and the entire film layer is fixed through the optical adhesive layer.

In another embodiment of the present application, in order to increase the transmittance of the light 110 , the optical module further includes an anti-reflection film, and the anti-reflection film is disposed on the fourth surface 222 . The anti-reflection coating increases the number of passing light rays 110 and reduces the reflection and absorption of the light rays 110 by the lens. In addition, the anti-reflection film can be installed in the way of pasting or coating, and the way of pasting is easy to operate. The way of coating can make the film layer of anti-reflection film more firm.

In one embodiment of the present application, the central thickness of the first lens 210 is T1, the central thickness of the second lens 220 is T2, and the distance between the first surface 211 and the light-emitting surface of the display 10 is L, then the following conditions are satisfied: 4mm<T1<8mm, 3mm<T2<7mm, 10mm<L<15mm. Wherein, L refers to the distance between two closest points between the first surface 211 and the light-emitting surface of the display 10 . If T1 is less than 4 mm, the first lens 210 is too thin, and if T1 is greater than 8 mm, the first lens 210 is too thick, which will increase the overall volume of the optical module. In addition, if the first lens 210 is too thin or too thick, the imaging quality will be reduced. Similarly, if T2 is less than 3mm, the second lens 220 is too thin, and if T2 is greater than 7mm, the second lens 220 is too thick, too thick will increase the overall volume of the optical module, and the second lens 220 will be too thin or too thick. result in reduced image quality. If L is less than 10mm, the distance between the first lens 210 and the display 10 is too close, and it is difficult for the light 110 to obtain a sufficient optical path, and the imaging quality will be reduced. If L is greater than 15mm, the distance between the first lens 210 and the display 10 is too far, which will increase the overall volume of the optical module.

In one of the embodiments of the present application, the radius value of the first surface 211 is R1, the conic coefficient of the first surface 211 is C1, the radius value of the second surface 212 is R2, and the conical coefficient of the second surface 212 is C2, The radius value of the fourth surface 222 is R4, and the conic coefficient of the fourth surface 222 is C4, which satisfies: 40mm<R1<60mm, C1<5; 70mm<R2<100mm, C2≤5; 150mm<R4<200mm, C4 ≤10. The above parameters are flexibly selected within the corresponding range, so as to ensure the imaging quality. If the selection of parameters exceeds the corresponding range, it will easily lead to the degradation of imaging quality.

The present invention also provides a head-mounted display device. The head-mounted display device includes a casing and an optical module as described above. The optical module is arranged on the casing. The casing can provide an installation space for supporting the optical module. In the casing, water vapor or dust from the external environment can also be prevented from falling into the interior of the optical module. If the total optical length of the optical module is TTL, it shall satisfy: TTL<25mm. For example, 24.6mm. It can be seen that the total optical length of the optical module is less than 25mm. Based on the above design of the optical module, the focal length of the optical module can be 22.9 mm, the focal length of the first lens 210 is 96.94 mm, and the focal length of the second lens 220 is 108.2 mm. The size of the light-emitting surface of the display 10 is 2.1 inches, and the size of each pixel is 24 microns. The imaging field angle is 100°-105°, for example, 100°, within this angle range, the user can observe clear imaging.

Wherein the design result of one embodiment refers to Table 1 and Table 2, respectively lists the optical surface number (Surface) numbered sequentially from the human eye (aperture STOP) to the display screen, the curvature (C) of each optical surface on the optical axis ), the distance (T) between each surface on the optical axis from the human eye (diaphragm) to the display screen and the next optical surface. And the even-order aspheric coefficients α2, α3, α4, where the aspheric coefficients can satisfy the following equation.

Among them, z is the coordinate along the optical axis, Y is the radial coordinate with the lens length as the unit, C is the curvature (1/R), k is the cone coefficient (Coin Constant), and αi is the coefficient of each high-order term, 2i is the order of aspherical coefficient (the order of Aspherical Coefficient). In this embodiment, taking into account the smoothness of the field curvature, the spherical coefficient without high-order term reaches 4th order.

Table I

Table II

It should be pointed out that the thickness in Table 1 refers to the distance between the optical surface and the next optical surface, the positive value of the thickness refers to the distance from the display 10 to the human eye 70, and the negative value of the thickness refers to the distance from the human eye 70 to the display. 10 directions of distance. The material refers to the material between the optical surface and the next optical surface. Among them, the meaning of MIRROR (reflection) is not material, but means that the optical surface has a reflection effect. The data represented by 4th in Table 2 is the fourth-order coefficient used to bring into the calculation formula of the corresponding surface type.

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

Claims

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

a display that emits light for an imaged display;

A cemented lens, the cemented lens is arranged in the light emitting direction of the display, the cemented lens includes a first lens and a second lens, the first lens and the second lens are arranged in sequence along the propagation direction of the optical path, the The first lens has a first surface facing the display and a second surface facing away from the display, the second lens has a third surface facing the display and a fourth surface facing away from the display, the The second surface is glued to the third surface, the third surface is raised toward the direction of the display, and the fourth surface is raised toward the direction away from the display;

a beam splitter, the beam splitter is disposed on the first surface;

a quarter wave plate disposed between the first lens and the second lens; and

a polarized reflective film, the polarized reflective film is arranged between the quarter wave plate and the second lens;

Defining the field curvature of the optical module as fv, it satisfies: 0.3mm<fv<0.8mm.
The optical module according to claim 1, wherein the pixel size of the display is defined as P, and the spot diameter of the full field of view of the optical module is D, and then D<P is satisfied.
The optical module according to claim 1, wherein the structure of the second surface is the same as that of the third surface.
The optical module according to any one of claims 1 to 3, wherein the first surface protrudes toward the display.
The optical module according to claim 4, wherein the optical module further comprises a polarizing film, and the polarizing film is disposed on a side of the first lens away from the display.
The optical module according to claim 5, wherein the polarizing film is arranged between the polarizing reflective film and the second lens, and the quarter wave plate, the polarizing reflective film and the The polarizing film is synthesized into an integral film layer.
The optical module according to any one of claims 1 to 3, wherein the optical module further comprises an anti-reflection film, and the anti-reflection film is provided on the fourth surface.
The optical module according to any one of claims 1 to 3, wherein the central thickness of the first lens is T1, the central thickness of the second lens is T2, and the first surface and the If the distance between the light-emitting surfaces of the above displays is L, then:

4mm<T1<8mm, 3mm<T2<7mm, 10mm<L<15mm.
The optical module according to any one of claims 1 to 3, wherein the radius value of the first surface is R1, the conic coefficient of the first surface is C1, and the radius of the second surface is Value is R2, the conic coefficient of the second surface is C2, the radius value of the fourth surface is R4, and the conical coefficient of the fourth surface is C4, then satisfy:

40mm<R1<60mm, C1<5;

70mm<R2<100mm, C2≤5;

150mm<R4<200mm, C4≤10.
A head-mounted display device, characterized in that the head-mounted display device includes a casing and an optical module according to any one of claims 1 to 9, the optical module is arranged in the casing, and the The total optical length of the above optical module is TTL, then it satisfies:

TTL<25mm.