Lens assembly, display module and head-mounted display device

Abstract

The embodiment of the utility model provides a lens assembly, a display module and head-mounted display equipment, and belongs to the technical field of head-mounted products. The lens assembly comprises a folding unit, a first Fresnel lens and a second Fresnel lens. Wherein the folding unit is provided with a folding cavity used for folding a light path. The first Fresnel lens is located on the light inlet side of the folding unit and used for transmitting the light to the folding unit. The first Fresnel lens, the folding unit and the second Fresnel lens are sequentially arranged in the optical axis direction of the first Fresnel lens, and the second Fresnel lens is located on the light emitting side of the folding unit and used for transmitting light emitted by the folding unit to human eyes. At least part of the lens outside the folded cavity is arranged to be the Fresnel lens, so that the overall thickness of the lens assembly is small.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of head-mounted products, in particular to a lens assembly, a display module and a head-mounted display device. BACKGROUND

[0002] At present, a head-mounted display device based on virtual reality (VR), augmented reality (AR), mixed reality (MR) and the like includes a lens assembly and a display screen. The lens assembly is located between the display screen and the eyes of a user. Light emitted by the display screen enters the eyes of the user through the lens assembly, and the user is shown the image displayed by the display screen. In the related art, the lens assembly is a Pancake lens group. However, each lens of the Pancake lens group is a lens with a continuous curved surface, and the thickness of each lens is large, and the overall thickness of the lens assembly is large. CONTENT OF THE UTILITY MODEL

[0003] Embodiments of the present application provide a lens assembly, a display module and a head-mounted display device. At least part of the lenses outside the folding cavity is set as a Fresnel lens, so that the overall thickness of the lens assembly is small.

[0004] In a first aspect, embodiments of the present application provide a lens assembly. The lens assembly includes a folding unit, a first Fresnel lens and a second Fresnel lens. The folding unit has a folding cavity for folding an optical path. The first Fresnel lens is located on the light-in side of the folding unit and is used for transmitting light to the folding unit. The second Fresnel lens is arranged along the optical axis direction of the first Fresnel lens, and the first Fresnel lens, the folding unit and the second Fresnel lens are arranged in sequence. The second Fresnel lens is located on the light-out side of the folding unit and is used for transmitting light emitted by the folding unit to the human eye.

[0005] Since the thickness of the Fresnel lens is smaller than that of the lens with a continuous curved surface, the lenses outside the folding cavity in the lens assembly are replaced by the Fresnel lens in the embodiments of the present application. The overall thickness of the lens assembly is small and the overall weight of the lens assembly is light while ensuring the display effect and myopia adjustment. In addition, the folding unit has a folding cavity for folding an optical path, so that the entire lens assembly is a Pancake lens group, which can further reduce the overall thickness and the overall weight of the lens assembly. Therefore, the lens assembly is a Hybrid-Pancake lens group containing the Fresnel lens, and the overall thickness of the lens assembly is small and the overall weight of the lens assembly is light. The Chinese name of the Hybrid-Pancake lens group can be a mixed Pancake lens group or a hybrid Pancake lens group.

[0006] In some possible implementation manners, the first Fresnel lens and the second Fresnel lens are not aligned.

[0007] In this implementation manner, the first Fresnel lens and the second Fresnel lens are not aligned, which can effectively reduce the deterioration of the brightness uniformity, reduce the impact on the human eye, and further improve the user experience.

[0008] In some possible implementation manners, the first Fresnel lens and the second Fresnel lens are not aligned.

[0009] In this implementation manner, the first Fresnel lens and the second Fresnel lens are not aligned, which can effectively reduce the deterioration of the brightness uniformity, reduce the impact on the human eye, and further improve the user experience.

[0010] In some possible implementation manners, the first Fresnel lens includes a first central region and a first edge region surrounding the first central region, and the first Fresnel lens is provided with the first Fresnel lens.

[0011] In this implementation manner, the first Fresnel lens is provided with the first Fresnel lens in the first edge region, and the first central region is free of the first Fresnel lens. In the first central region, the human eye will not see the first Fresnel lens, and the display effect of the picture area corresponding to the first central region can be improved. Since the human eye has poor resolution for the first edge region, the human eye will not observe the first Fresnel lens, and the impact of the first Fresnel lens on the human eye can be reduced, and the user experience can be improved.

[0012] In some possible implementation manners, the first central region has an angle of view relative to the human eye that is greater than or equal to 10°.

[0013] Generally, the main viewing angle of the human eye is about 10°. By setting the angle of view of the first central region to be greater than or equal to 10°, the human eye can avoid being free of the first Fresnel lens in the main viewing range, the impact of the first Fresnel lens on the human eye can be reduced, and the user experience can be improved.

[0014] In some possible implementation manners, the second Fresnel lens includes a second central region and a second edge region surrounding the second central region, and the second Fresnel lens is provided with the second Fresnel lens.

[0015] In the implementation, the second Fresnel lens is arranged inside the second edge area, and the second central area is free of the lines, so that the lines cannot be seen by the human eye within the corresponding visual angle of the second central area, and the display effect of the picture area corresponding to the second central area can be improved. Since the resolution of the human eye for the second edge area is weak, the lines of the second Fresnel lens cannot be observed, the influence of the lines on the human eye can be reduced, and the user's viewing experience can be improved.

[0016] In some possible implementations, the visual angle of the second central area relative to the human eye is greater than or equal to 10°.

[0017] Generally, the main viewing visual angle of the human eye is about 10°, and the visual angle of the second central area is greater than or equal to 10°, so that the main viewing range of the human eye is free of the lines, the influence of the lines on the human eye is reduced, and the user's experience is improved.

[0018] In some possible implementations, the number of the first Fresnel lenses is a plurality, and the lines of any two first Fresnel lenses do not coincide.

[0019] In the implementation, the lines of any two first Fresnel lenses do not coincide, the deterioration of the brightness uniformity can be effectively reduced, the influence on the human eye can be reduced, and the user's experience is further improved.

[0020] In some possible implementations, the optical axes of any two first Fresnel lenses coincide, and the line distances of any two first Fresnel lenses are different.

[0021] In the implementation, the line distances of any two first Fresnel lenses are different, so that the lines of any two first Fresnel lenses do not coincide, and the purpose of reducing the deterioration of the brightness uniformity is achieved.

[0022] In some possible implementations, the number of the second Fresnel lenses is a plurality, and the lines of any two second Fresnel lenses do not coincide.

[0023] In the implementation, the lines of any two second Fresnel lenses do not coincide, the deterioration of the brightness uniformity can be effectively reduced, the influence on the human eye can be reduced, and the user's experience is further improved.

[0024] In some possible implementations, the optical axes of any two second Fresnel lenses coincide, and the line distances of any two second Fresnel lenses are different.

[0025] In the implementation, the line distances of any two second Fresnel lenses are different, so that the lines of any two second Fresnel lenses do not coincide, and the purpose of reducing the deterioration of the brightness uniformity is achieved.

[0026] In some possible implementations, the folding unit includes a first optical element and a second optical element. The first optical element has a first surface facing the first Fresnel lens. The second optical element is located between the first optical element and the second Fresnel lens and has a second surface facing the second Fresnel lens, and the first surface and the second surface form a folding cavity.

[0027] In this implementation, the first optical element and the second optical element form a folding cavity, which can fold the optical path and reduce the thickness of the lens assembly.

[0028] In a second aspect, an embodiment of the present application provides a display module, which includes a display device and the lens assembly of any one of the first aspect, and the lens assembly is arranged on the light-emitting side of the display device.

[0029] In a third aspect, an embodiment of the present application provides a head-mounted display device, which includes a carrying assembly and the display module of the second aspect, and the display module is mounted on the carrying assembly.

[0030] In some possible implementations, the number of the display modules is two, which are a first display module and a second display module. The first display module and the second display module have Fresnel lenses with different groove patterns.

[0031] In this implementation, the first display module is used to display images to the left eye of a user, and the second display module is used to display images to the right eye of the user. In this case, the groove patterns of the Fresnel lenses in the display modules corresponding to the left eye and the right eye do not coincide, which reduces the deterioration of the uniformity of brightness by using the characteristics of binocular fusion, reduces the impact on the human eye, and improves the user experience.

[0032] In some possible implementations, the groove pitch of the Fresnel lens of the first display module is different from the groove pitch of the Fresnel lens of the second display module, so that the groove patterns of the Fresnel lenses of the two display modules do not coincide. At the same time, the two display modules do not need to be out-turned, which can reduce the space occupied by the display modules in the head-mounted display device, and is helpful to the lightweight design of the head-mounted display device. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 FIG. 1 is a schematic structural diagram of a head-mounted display device provided by an embodiment of the present application;

[0034] Figure 2 FIG. 2 is a schematic diagram of a display module in the related art;

[0035] Figure 3 FIG. 3 is a schematic diagram of the polarization of a Pancake lens group in FIG. 1; Figure 2

[0036] FIG. 4 is a schematic diagram of the polarization of a Pancake lens group in FIG. 2.Figure 4 This is a schematic diagram of a display module provided in an embodiment of this application;

[0037] Figure 5 for Figure 4 A schematic diagram showing the relative positions of the textures of the first Fresnel lens and the second Fresnel lens.

[0038] Figure 6 for Figure 1 A schematic diagram showing the relationship between the Fresnel lenses of the two display modules in the head-mounted display device shown.

[0039] Figure 7 A schematic diagram of another display module provided in an embodiment of this application;

[0040] Figure 8 for Figure 7 A schematic diagram of the first Fresnel lens in the diagram;

[0041] Figure 9 for Figure 7 A schematic diagram of the second Fresnel lens in the diagram.

[0042] Explanation of reference numerals in the attached figures:

[0043] 100, Display module; 100a, First display module; 100b, Second display module;

[0044] 200, Lens assembly; 200a, First lens assembly; 200b, Second lens assembly;

[0045] 300, Display device; 300a, First display device; 300b, Second display device;

[0046] 10. Folding unit;

[0047] 11. First optical element; 11a. First surface; 111. First light-transmitting substrate; 112. Semi-transparent and semi-reflective film;

[0048] 12. Second optical element; 12a. Second surface; 121. Second light-transmitting substrate; 122. Second quarter-wave plate; 123. Polarizing reflective film;

[0049] 20. First Fresnel lens; 21. First central region; 22. First edge region;

[0050] 30. Second Fresnel lens; 31. Second central region; 32. Second peripheral region. Detailed Implementation

[0051] The terminology used in the implementation section of this application is for the purpose of explaining specific embodiments of this application only, and is not intended to limit this application.

[0052] For the convenience of understanding, the technical terms involved in the present application are explained and described below.

[0053] A polarizer (POL) is a kind of optical filter. A polarizer is used to absorb or reflect light of one polarization direction and transmit light of another orthogonal polarization direction. The transmittance of light is directly related to its polarization state. Polarizers can generally be divided into absorptive polarizers and reflective polarizers (RP). An absorptive polarizer can strongly absorb one of the orthogonal polarization components of the incident linearly polarized light, and weakly absorb the other component. A reflective polarizer can transmit linearly polarized light of a certain direction and reflect light of a polarization direction perpendicular to the transmitted direction. An absorptive polarizer may, for example, be a dichroic polarizer, and a reflective polarizer may, for example, be a polarization beam splitter using birefringence.

[0054] Light wave is a kind of electromagnetic wave, which is composed of electric field and magnetic field. Both are vectors perpendicular to the direction of light wave propagation. The light wave propagates in the electric field and the magnetic field to become polarized. When the light vector only vibrates along a fixed direction, this light is called linearly polarized light, also known as plane polarized light. When both vectors rotate around themselves, the light wave is in a circularly polarized state. The characteristic of circularly polarized light is that the light vector rotates (left-handed or right-handed) at a certain frequency in the plane perpendicular to the direction of light propagation. If the trajectory of the light vector endpoint is a circle, this light is called circularly polarized light.

[0055] For natural light (or non-polarized light) incident on a polarizer, the outgoing light becomes linearly polarized light. For linearly polarized light incident on a polarizer, the outgoing light is still linearly polarized light.

[0056] S-polarized light, also called S light or vertically polarized light. For S-polarized light, the electric field vibration direction is perpendicular to the incident plane.

[0057] P-polarized light, also called P light or horizontally polarized light. For P-polarized light, the electric field vibration direction is parallel to the incident plane.

[0058] Polarization direction is also called polarization direction or polarization direction. This is because there is a certain characteristic direction in the polarizer, called the polarization direction, and the polarizer only allows light parallel to the polarization direction to pass through, while absorbing or reflecting light perpendicular to the direction.

[0059] A quarter-wave plate (QWP) can also be referred to as a 90° phase retardation plate. A quarter-wave plate is made of a birefringent material. When the optical vector of linearly polarized light is at ±45° to the fast axis or the slow axis of the quarter-wave plate, the light passing through the quarter-wave plate is circularly polarized light; conversely, when circularly polarized light passes through the quarter-wave plate, it becomes linearly polarized light. The direction of the optical vector of light propagating slowly in the quarter-wave plate is referred to as the slow axis direction of the quarter-wave plate.

[0060] A half-transmission half-reflection film is a film that enables incident light to be partially transmitted and partially reflected. For example, a film with a transmissivity and reflectivity of 50%. Among them, transmission is the phenomenon of the exit of incident light after refraction through an object. The object that is transmitted is a transparent or translucent object, such as glass or a color filter. If the transparent object is colorless, most of the light is transmitted through the object, except for a small amount of light that is reflected. In order to represent the degree of light transmission through the object, the ratio of the light intensity of the transmitted light to the light intensity of the incident light after the incident light is transmitted through the film represents the transmissivity. The ratio of the light intensity of the reflected light to the light intensity of the incident light represents the reflectivity.

[0061] Embodiments of the present application provide a head-mounted display device, which is a device that can be worn on the head of a user and can be used to display images in front of the user's line of sight. The head-mounted display device can include, but is not limited to, a virtual reality (VR) device, an augmented reality (AR) device, or a mixed reality (MR) device, etc. Embodiments of the present application take the head-mounted display device as an AR device as an example for illustration, for example, the head-mounted display device can be AR glasses.

[0062] In embodiments of the present application, the head-mounted display device includes a display module 100 and a bearing assembly. The display module 100 is fixedly installed on the bearing assembly, and the display module 100 can display virtual images to the user and also allow the user to view the real-world environment. The bearing assembly is used to wear the head-mounted display device on the head of the user, for example, the bearing assembly can be a frame, the frame includes a front frame and two temple legs respectively arranged at both ends of the front frame in a first direction, the two temple legs are respectively used to hook on the two ears of the user, and the front frame can be placed on the nose of the user to wear the head-mounted display device on the head of the user.

[0063] In some examples, the temple legs can be fixedly arranged with the front frame. For example, the temple legs can be an integral structure with the front frame.

[0064] In other examples, the temple legs can be hingedly connected with the front frame through a hinge assembly, so that the temple legs and the front frame can be folded to facilitate the storage of the head-mounted display device.

[0065] Figure 1 A schematic diagram of an architecture of a head-mounted display device is provided in embodiments of the present application.

[0066] The display module 100 is configured to display images to a human eye. As shown in Figure 1 the number of display modules 100 is two, which are a first display module 100a and a second display module 100b. When a user wears the head-mounted display device, the first display module 100a can be configured to display images to the user's left eye, and the second display module 100b can be configured to display images to the user's right eye.

[0067] In embodiments of the present application, as shown in Figure 1 the display module 100 includes a display device 300 and a lens assembly 200, and the lens assembly 200 is located on the light-emitting side of the display device 300. When the user wears the head-mounted display device, the lens assembly 200 is located between the display device 300 and the user's eye, and the image light emitted by the display device 300 enters the eye through the lens assembly 200, so that the user sees the images displayed by the display device 300.

[0068] Generally, the number of display modules 100 is two, and therefore, as shown in Figure 1 the first display module 100a includes a first display device 300a and a first lens assembly 200a, and the second display module 100b includes a second display device 300b and a second lens assembly 200b. When the user wears the head-mounted display device, the first lens assembly 200a is located between the first display device 300a and the user's left eye, and the second lens assembly 200b is located between the second display device 300b and the user's right eye, and the light emitted by the first display device 300a converges to the user's left eye through the first lens assembly 200a, and the light emitted by the second display device 300b converges to the user's right eye through the second lens assembly 200b.

[0069] In some embodiments, the first display device 300a and the second display device 300b can be two independent display devices 300. In other embodiments, the first display device 300a and the second display device 300b can be two display regions on the same display device 300.

[0070] The specific structure of the display device 300 is not specifically limited here. For example, the display device 300 includes a display, a polarizer and a first quarter-wave plate arranged in sequence, and the first quarter-wave plate is located between the polarizer and the lens assembly 200. The polarizer is configured to convert the light emitted by the display into linearly polarized light, and the first quarter-wave plate is configured to convert the linearly polarized light from the polarizer into circularly polarized light.

[0071] For example, the display can be a liquid crystal display (LCD), an organic light-emitting diode (OLED), a micro light-emitting diode (micro LED), an active matrix organic light-emitting diode (AMOLED), a flexible light-emitting diode (FLED), or a quantum dot light-emitting diode (QLED). OLEDs have high luminous efficiency and high contrast; mini LED displays have high brightness and can be used in scenarios requiring strong luminous brightness.

[0072] For example, the display can also be a reflective display. Examples include liquid crystal on silicon (LCOS) displays, or reflective displays based on digital micromirror devices (DMDs). LCOS and DMDs, due to their reflective structure, have higher resolution or aperture ratios.

[0073] Figure 2 This is a schematic diagram of a display module in related technologies.

[0074] In related technologies, such as Figure 2 As shown, the lens assembly 500 is a pancake lens assembly, which includes a first lens 510, a second lens 520, a third lens 530, and a fourth lens 540 arranged sequentially along the light emission direction of the display device 400. The first lens 510 is closer to the display device 400, and the fourth lens 540 is closer to the human eye. The second lens 520 includes a first light-transmitting substrate 521 and a semi-transparent, semi-reflective film 522, with the semi-transparent, semi-reflective film 522 located between the first light-transmitting substrate 521 and the first lens 510. The third lens 530 includes a second light-transmitting substrate 531, a first quarter-wave plate 532, and a polarizing reflective film 533, with the first quarter-wave plate 532 located between the second light-transmitting substrate 531 and the polarizing reflective film 533, and the polarizing reflective film 533 located between the first quarter-wave plate 532 and the fourth lens 540. The display device 400 includes a display 410, a polarizer 420, and a second quarter-wave plate 430 arranged in sequence, with the second quarter-wave plate 430 located between the polarizer 420 and the first lens 510.

[0075] Figure 3 For Figure 2 Pancake lens group light polarization schematic diagram in FIG.

[0076] As Figure 3 shown, the light from the display 410 is folded in the Pancake lens group and finally exits into the user's eye. The multi-layer coating in the Pancake lens group can make the light fold between the film layers. Specifically, the light emitted by the display screen is modulated into linearly polarized light after passing through the polarizer 420, without loss of generality, the polarization direction can be assumed to be along the y-axis direction. After passing through the second quarter-wave plate 430, the light becomes right-handed polarized light, and the fast axis direction of the second quarter-wave plate 430 is 45° to the y-axis. Thereafter, the light passes through the first lens 510 to the half-reflective half-transmissive film, a portion of the light is reflected, and another portion of the light is transmitted and passes through the first quarter-wave plate 532 to the polarized reflective film 533. The fast axis direction of the first quarter-wave plate 532 is the same as that of the second quarter-wave plate 430, at this time, the light is modulated into linearly polarized light again, and the polarization direction is along the x-axis direction. The polarized reflective film 533 can reflect the polarized light in the x-axis direction and transmit the polarized light in the y-axis direction. Therefore, the light is reflected and transmits through the first quarter-wave plate 532 to the half-reflective half-transmissive film, at this time, the light is right-handed polarized light. As before, a portion of the light is transmitted and another portion of the light is reflected. The polarization state of the reflected light becomes left-handed polarized light, and after passing through the first quarter-wave plate 532 again, the light is modulated into linearly polarized light again, and the polarization direction is along the y-axis direction. According to the characteristics of the polarized reflective film 533, the light will be transmitted through the polarized reflective film 533 and exit, and finally pass through the fourth lens 540 into the human eye.

[0077] It can be seen that the half-reflective half-transmissive film 522 of the first lens 510 and the polarized reflective film 533 of the second lens 520 form a folding cavity, which refers to a path designed to change direction multiple times in a limited space through reflection and folding, that is, the folding path is realized through the folding cavity. In addition, the Pancake lens group is composed of four lenses, which can improve aberration correction, improve image quality, and improve image clarity and detail performance. However, the four lenses are all lenses with continuous curved surfaces, and the thickness of each lens is large, resulting in a large thickness of the Pancake lens group. In addition, the weight of each lens is heavy, resulting in a heavy overall weight of the Pancake lens group.

[0078] Therefore, the lens assembly 200 provided by the embodiments of the present application is a Hybrid-Pancake lens assembly, which has a folding cavity and can allow light to travel a longer physical path in a compact space before entering the eye, thereby achieving a larger eye movement range, higher image quality and a thinner design without increasing the device. Meanwhile, since the thickness of the Fresnel lens is smaller than that of a lens with a continuous curved surface, the Fresnel lens is used to replace the lenses outside the folding cavity, such as the first lens and the fourth lens in the prior art, so that the thickness of the lens assembly 200 is smaller and the weight is lighter while the image quality is ensured.

[0079] The lens assembly 200 provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0080] Figure 4 A schematic diagram of a display module provided by the embodiments of the present application.

[0081] As shown in Figure 4 , the lens assembly 200 provided by the embodiments of the present application includes a folding unit 10, a first Fresnel lens 20 and a second Fresnel lens 30. The folding unit 10 has a folding cavity for folding the light path, and the folding cavity refers to a path designed to change direction multiple times by reflection and folding in a limited space. The first Fresnel lens 20 is located on the light-in side of the folding unit 10, and is used to transmit the light emitted by the display device 300 to the folding unit 10. Along the optical axis direction (such as the z direction in Figure 4 , the first Fresnel lens 20, the folding unit 10 and the second Fresnel lens 30 are arranged in sequence, and the second Fresnel lens 30 is located on the light-out side of the folding unit 10, and is used to transmit the light emitted by the folding unit 10 to the human eye.

[0082] In the embodiments of the present application, by arranging the Fresnel lenses on the light-in side and the light-out side of the folding unit 10, the lens assembly 200 has a larger number of lenses, which can improve aberration correction, improve image quality, and improve image clarity and detail performance, thereby ensuring the display effect of the display module 100. In addition, myopia adjustment can be performed by moving the first Fresnel lens 20 and / or the second Fresnel lens 30, thereby improving user experience.

[0083] Compared with a lens with a continuous curved surface, the first Fresnel lens 20 and the second Fresnel lens 30 are smaller in thickness and lighter in weight, which can reduce the thickness and weight of the lens assembly 200. In addition, the folding unit 10 has a folding cavity with a folded light path, which can further reduce the thickness of the lens assembly 200. Therefore, the lens assembly 200 provided in the embodiments of the present application combines the advantages of the traditional Pancake lens and the Fresnel lens, so that the lens assembly 200 is a Hybrid-Pancake lens containing a Fresnel lens, which has a small overall thickness and a light overall weight while ensuring display effect. The Chinese name of the Hybrid-Pancake lens can be hybrid Pancake lens or hybrid (crossed) Pancake lens.

[0084] Figure 5 For Figure 4 the relative positions of the grooves of the first Fresnel lens and the grooves of the second Fresnel lens. Among them, Figure 5 w1 in the first Fresnel lens is the groove, Figure 5 w2 in the second Fresnel lens is the groove.

[0085] In some possible implementations, as shown in Figure 5 , the grooves of the first Fresnel lens 20 and the grooves of the second Fresnel lens 30 do not coincide (overlap), which can effectively alleviate the deterioration of the brightness uniformity, reduce the impact on the human eye, and further improve the user experience.

[0086] Among them, the deterioration of the brightness uniformity may have the following effects on the human eye: 1, visual fatigue: uneven brightness distribution will make the eyes need to constantly adjust to adapt to different light intensity areas, which may cause eye muscle tension and fatigue. 2, image perception difficulty: uneven brightness will affect the overall clarity and contrast of the image, making it difficult to identify some details. 3, glare and spot effect: when some areas are particularly bright, glare or spots may be formed, which will interfere with the user's line of sight and affect visual comfort. 4, color distortion: uneven brightness may also cause poor color performance, such as less vibrant colors or color cast.

[0087] Among them, the grooves of the Fresnel lens can also be called Fresnel grooves. In addition, the grooves of the Fresnel lens refer to the unique concentric ring structure on its surface, which is formed by decomposing the continuous curved surface of a traditional convex lens or concave lens into a series of stepped or jagged ring-shaped areas.

[0088] It should be noted that in some scenarios, the Fresnel grooves of the first Fresnel lens 20 and the Fresnel grooves of the second Fresnel lens 30 can also coincide.

[0089] In some possible implementation manners, the optical axis of the first Fresnel lens 20 coincides with the optical axis of the second Fresnel lens 30, and the pitch of the first Fresnel lens 20 is different from the pitch of the second Fresnel lens 30. In this implementation manner, by making the pitch of the first Fresnel lens 20 different from the pitch of the second Fresnel lens 30, the grooves of the first Fresnel lens 20 do not coincide with the grooves of the second Fresnel lens 30, so as to reduce the deterioration of the brightness uniformity and thus reduce the impact on the human eye.

[0090] As shown in FIG. 1, the number of the first Fresnel lens 20 is one, and of course, the number of the first Fresnel lens 20 can also be more than one. In some possible implementation manners, the number of the first Fresnel lens 20 is more than one, for example, the number of the first Fresnel lens 20 is two, and both of the two first Fresnel lenses 20 are located on the light-incident side of the folding unit 10. Figure 4 When the number of the first Fresnel lens 20 is at least two, the grooves of any two first Fresnel lenses 20 can not coincide, so as to reduce the impact of the grooves of the first Fresnel lens 20 on the human eye and improve the user experience. Of course, the grooves of any two first Fresnel lenses 20 can also coincide, or when the number of the first Fresnel lens 20 is at least three, the grooves of part of the first Fresnel lenses 20 do not coincide.

[0091] In some possible implementation manners, the optical axes of any two first Fresnel lenses 20 coincide, and the pitches of any two first Fresnel lenses 20 are different. In this implementation manner, by making the pitches of any two first Fresnel lenses 20 different, the grooves of any two first Fresnel lenses 20 do not coincide, so as to reduce the impact of the grooves of the first Fresnel lens 20 on the human eye.

[0092] As shown in FIG. 1, the number of the second Fresnel lens 30 is one, and of course, the number of the second Fresnel lens 30 can also be more than one. In some possible implementation manners, the number of the second Fresnel lens 30 is more than one, for example, the number of the second Fresnel lens 30 is two, and both of the two second Fresnel lenses 30 are located on the light-incident side of the folding unit 10.

[0093] Figure 4 When the number of the second Fresnel lens 30 is at least two, the grooves of any two second Fresnel lenses 30 can not coincide, so as to reduce the impact of the grooves of the second Fresnel lens 30 on the human eye and improve the user experience. Of course, the grooves of any two second Fresnel lenses 30 can also coincide, or when the number of the second Fresnel lens 30 is at least three, the grooves of part of the second Fresnel lenses 30 do not coincide.

[0094] In some possible implementation manners, the optical axes of any two first Fresnel lenses 20 coincide, and the pitches of any two first Fresnel lenses 20 are different. In this implementation manner, by making the pitches of any two first Fresnel lenses 20 different, the grooves of any two first Fresnel lenses 20 do not coincide, so as to reduce the impact of the grooves of the first Fresnel lens 20 on the human eye.

[0095] ​In some possible implementation manners, the optical axes of any two second Fresnel lenses 30 coincide, and the pitches of any two second Fresnel lenses 30 are different. In this implementation manner, by making the pitches of any two second Fresnel lenses 30 different, the pitches of any two second Fresnel lenses 30 do not coincide, so that the purpose of reducing the influence of the pitches of the second Fresnel lenses 30 on the human eye is achieved.

[0096] In the foregoing, the pitch relationship between the multiple Fresnel lenses in a single display module 100 is described, that is, the pitches of the multiple Fresnel lenses in a single display module 100 can overlap (coincide) or not overlap (coincide). As described above, two display modules 100 are arranged in the head-mounted display device, which are the first display module 100a and the second display module 100b. At this time, the pitches of the Fresnel lenses of the first display module 100a and the second display module 100b can also overlap (coincide) or not overlap (coincide).

[0097] Figure 6 For Figure 1 the pitches of the Fresnel lenses of the two display modules in the head-mounted display device are shown. Among them, Figure 6 w3 in the foregoing is the pitch of the Fresnel lens of the first display module 100a, and w4 is the pitch of the Fresnel lens of the second display module 100b.

[0098] In some possible implementation manners, as shown in Figure 6 the pitch of the Fresnel lens of the first display module 100a does not coincide (overlap) with the pitch of the Fresnel lens of the second display module 100b. Specifically, the pitch of the first Fresnel lens 20 of the first display module 100a does not coincide with the pitches of the first Fresnel lens 20 and the second Fresnel lens 30 of the second display module 100b, and the pitch of the second Fresnel lens 20 of the first display module 100a does not coincide with the pitches of the first Fresnel lens 20 and the second Fresnel lens 30 of the second display module 100b.

[0099] The first display module 100a is configured to display images to the left eye of the user, and the second display module 100b is configured to display images to the right eye of the user. At this time, the pitches of the Fresnel lenses in the display modules 100 corresponding to the left eye and the right eye do not coincide, the characteristics of binocular fusion are utilized to reduce the deterioration of the brightness uniformity, the influence on the human eye is reduced, and the user experience is improved.

[0100] In some possible implementation manners, the pitches of the Fresnel lenses in the first display module 100a and the second display module 100b can be made not to coincide in a binocular eversion manner. Specifically, the optical axes of the Fresnel lenses of the first display module 100a and the second display module 100b intersect with the line of sight of the human eye and do not coincide. In some possible implementation manners, the pitches of the Fresnel lenses in the first display module 100a and the second display module 100b can be made not to coincide in a binocular eversion manner. Specifically, the optical axes of the Fresnel lenses of the first display module 100a and the second display module 100b intersect with the line of sight of the human eye and do not coincide.

[0101] In some other possible implementations, the ridge pattern of the Fresnel lens in the first display module 100a differs from that in the second display module 100b. Specifically, the ridge pattern of the first Fresnel lens 20 in the first display module 100a differs from that of the first Fresnel lens 20 and the second Fresnel lens 30 in the second display module 100b, and the ridge pattern of the second Fresnel lens 30 in the first display module 100a differs from that of the first Fresnel lens 20 and the second Fresnel lens 30 in the second display module 100b. This achieves the goal of non-overlapping ridge patterns in the Fresnel lenses of the two display modules 100. Simultaneously, the two display modules 100 do not need to employ binocular outward rotation, reducing the space occupied by the display modules 100 in the head-mounted display device and contributing to a thinner and lighter design for the head-mounted display device.

[0102] Figure 7 This is a schematic diagram of another display module provided in an embodiment of this application. Figure 8 for Figure 7 A schematic diagram of the first Fresnel lens in the diagram. Figure 9 for Figure 7 A schematic diagram of the second Fresnel lens in the diagram.

[0103] In some possible implementations, such as Figure 8 As shown, the first Fresnel lens 20 includes a first central region 21 and a first edge region 22, with the first edge region 22 surrounding the first central region 21. The texture of the first Fresnel lens 20 is located inside the first edge region 22. In this implementation, the texture of the first Fresnel lens 20 is set inside the first edge region 22, while the interior of the first central region 21 has no texture. The viewing angle of the first central region 21 (e.g., ...) Figure 7 In the first central area 21, the texture is not visible to the human eye, thus improving the display effect of the corresponding screen area. Since the human eye has a weak ability to distinguish the first edge area 22, the texture of the first Fresnel lens 20 is not observed, reducing the impact of the texture on the human eye and improving the user's viewing experience.

[0104] For example, the first central region 21 relative to the human eye's viewing angle (e.g. Figure 7 As shown in Figure a), the angle is greater than or equal to 10°, which determines the range of the first central area 21. Typically, the viewing angle of the human eye's primary viewing area is around 10°. Therefore, setting the viewing angle of the first central area 21 to greater than or equal to 10° avoids the absence of texture within the primary viewing area, reduces the impact of texture on the human eye, and improves the user experience.

[0105] Among them, such as Figure 7As shown, the viewing angle of the first central region 21 refers to the angle formed by the light rays drawn from the opposite ends of the first central region 21 at the optical center of the human eye when viewing the Fresnel lens. Therefore, the viewing angle for the human eye to fully see the first central region 21 must be greater than or equal to 10°.

[0106] In some embodiments, the viewing angle of the first central region 21 relative to the human eye may also be less than 100°. In this case, the viewing angle of the first central region 21 relative to the human eye is between 10° and 100°, which can avoid the first edge region 22 being too small due to the large area of ​​the first central region 21.

[0107] In some possible implementations, such as Figure 9 As shown, the second Fresnel lens 30 includes a second central region 31 and a second edge region 32. The second edge region 32 surrounds the second central region 31, and the texture of the second Fresnel lens 30 is located inside the second edge region 32. In this implementation, the texture of the second Fresnel lens 30 is set inside the second edge region 32, and there is no texture inside the second central region 31. The viewing angle corresponding to the second central region 31 (e.g., Figure 7 As shown in (b), the texture is not visible to the human eye, which improves the display effect of the image area corresponding to the second central area 31. Since the human eye has a weak ability to resolve the second edge area 32, the texture of the second Fresnel lens 30 will not be observed, which can reduce the impact of texture on the human eye and improve the user's viewing experience.

[0108] For example, the second central region 31 relative to the human eye's viewing angle (e.g. Figure 7 As shown in b), the angle is greater than or equal to 10°, which determines the range of the second central area 31. Typically, the viewing angle of the human eye's primary viewing area is around 10°. Therefore, setting the viewing angle of the second central area 31 to greater than or equal to 10° avoids the absence of texture within the primary viewing area, reduces the impact of texture on the human eye, and improves the user experience.

[0109] Among them, such as Figure 7 As shown, the viewing angle of the second central region 31 refers to the angle formed by the light rays drawn from the opposite ends of the second central region 31 at the optical center of the human eye when viewing the Fresnel lens. Therefore, the viewing angle for the human eye to fully perceive the second central region 31 must be greater than or equal to 10°.

[0110] In some embodiments, the viewing angle of the second central region 31 relative to the human eye may also be less than 100°. In this case, the viewing angle of the second central region 31 relative to the human eye is between 10° and 100°, which can avoid the second edge region 32 being too small due to the area of ​​the second central region 31 being too large.

[0111] For example, such as Figure 4As shown, the folding unit 10 comprises a first optical element 11 and a second optical element 12. The first optical element 11 has a first surface 11a facing the first Fresnel lens 20. The second optical element 12 is located between the first optical element 11 and the second Fresnel lens 30, and has a second surface 12a facing the second Fresnel lens 30, so that a folding cavity is formed between the first surface 11a and the second surface 12a, and the optical path can be folded.

[0112] The specific structure of the first optical element 11 is not limited herein. For example Figure 4 As shown, the first optical element 11 comprises a first light-transmitting base 111 and a semi-transparent and semi-reflective film 112, and the semi-transparent and semi-reflective film 112 is located between the first light-transmitting base 111 and the first Fresnel lens 20, and the semi-transparent and semi-reflective film 112 serves as the first surface 11a of the first optical element 11. The semi-transparent and semi-reflective film 112 is used to transmit the circularly polarized light from the first Fresnel lens 20 and reflect the reflected light from the second surface 12a of the second optical element 12.

[0113] The specific structure of the second optical element 12 is not limited herein. For example Figure 4 As shown, the second optical element 12 comprises a second light-transmitting base 121, a second quarter-wave plate 122 and a polarization reflection film 123, the second quarter-wave plate 122 is located between the second light-transmitting base 121 and the polarization reflection film 123, and the polarization reflection film 123 is located between the first quarter-wave plate 122 and the second Fresnel lens 30, and the polarization reflection film 123 serves as the second surface 12a of the second optical element 12. The second quarter-wave plate 122 is used to convert linearly polarized light and circularly polarized light, and the polarization reflection film 123 is used to transmit first linearly polarized light and reflect second linearly polarized light, one of the first linearly polarized light and the second linearly polarized light is P-polarized light, and the other is S-polarized light.

[0114] It should be noted that the specific structure of the first optical element 11 and the second optical element 12 is not limited to the structure described in the embodiments of the present application.

[0115] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connecting” should be understood in a broad sense, for example, can be fixed connection, or indirect connection through an intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances. The terms “first”, “second”, “third”, “fourth” and the like (if any) are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0116] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the embodiments of the present application are described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A lens assembly (200), characterized in that, include: The folding unit (10) has a folding cavity for folding the optical path; A first Fresnel lens (20) is located on the light-inlet side of the folding unit (10) and is used to transmit light to the folding unit (10). The second Fresnel lens (30) is arranged in sequence along the optical axis of the first Fresnel lens (20), the first Fresnel lens (20), the folding unit (10) and the second Fresnel lens (30). The second Fresnel lens (30) is located on the light-emitting side of the folding unit (10) and is used to transmit the light emitted by the folding unit (10) to the human eye.

2. The lens assembly (200) according to claim 1, characterized in that, The texture of the first Fresnel lens (20) does not overlap with the texture of the second Fresnel lens (30).

3. The lens assembly (200) according to claim 2, characterized in that, The optical axis of the first Fresnel lens (20) coincides with the optical axis of the second Fresnel lens (30), and the pitch of the first Fresnel lens (20) is different from that of the second Fresnel lens (30).

4. The lens assembly (200) according to claim 1, characterized in that, The first Fresnel lens (20) includes a first central region (21) and a first edge region (22) surrounding the first central region (21), and the texture of the first Fresnel lens (20) is located inside the first edge region (22).

5. The lens assembly (200) according to claim 4, characterized in that, The first central region (21) has a viewing angle of 10° or greater than or equal to that of the human eye.

6. The lens assembly (200) according to any one of claims 1 to 5, characterized in that, The second Fresnel lens (30) includes a second central region (31) and a second edge region (32) surrounding the second central region (31), and the texture of the second Fresnel lens (30) is located inside the second edge region (32).

7. The lens assembly (200) according to claim 6, characterized in that, The second central area (31) has a viewing angle of 10° or greater than or equal to that of the human eye.

8. The lens assembly (200) according to any one of claims 1 to 5, characterized in that, There are multiple first Fresnel lenses (20), and the patterns of any two first Fresnel lenses (20) do not overlap.

9. The lens assembly (200) according to claim 8, characterized in that, The optical axes of any two first Fresnel lenses (20) coincide, and the fringe spacing of any two first Fresnel lenses (20) is different.

10. The lens assembly (200) according to any one of claims 1 to 5, characterized in that, There are multiple second Fresnel lenses (30), and the patterns of any two second Fresnel lenses (30) do not overlap.

11. The lens assembly (200) according to claim 10, characterized in that, The optical axes of any two second Fresnel lenses (30) coincide, and the fringe spacing of any two second Fresnel lenses (30) is different.

12. The lens assembly (200) according to any one of claims 1 to 5, characterized in that, The folding unit (10) includes: The first optical element (11) has a first surface (11a) facing the first Fresnel lens (20). The second optical element (12) is located between the first optical element (11) and the second Fresnel lens (30) and has a second surface (12a) facing the second Fresnel lens (30), and the folded cavity is formed between the first surface (11a) and the second surface (12a).

13. A display module (100), characterized in that, It includes a display device (300) and a lens assembly (200) as described in any one of claims 1 to 12, wherein the lens assembly (200) is disposed on the light-emitting side of the display device (300).

14. A head-mounted display device, characterized in that, It includes a carrier component and a display module (100) as described in claim 13, the display module (100) being mounted on the carrier component.

15. The head-mounted display device according to claim 14, characterized in that, The number of display modules (100) is two, namely a first display module (100a) and a second display module (100b), wherein: The texture of the Fresnel lens of the first display module (100a) does not overlap with the texture of the Fresnel lens of the second display module (100b).

16. The head-mounted display device according to claim 15, characterized in that, The ridge spacing of the Fresnel lens in the first display module (100a) is different from that of the Fresnel lens in the second display module (100b).

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