Optical module, optical system, and display device

Abstract

This application provides an optical module, an optical system, and a display device. The optical module includes a first lens, a second lens, and a composite film arranged sequentially. The first lens includes a first light-incident surface and a first light-exit surface that are opposite to each other. The second lens includes a second light-incident surface and a second light-exit surface that are opposite to each other. The second light-incident surface and the first light-exit surface are arranged opposite each other. The composite film includes a polarizing reflective film and a phase retardation film. The phase retardation film is attached to the polarizing reflective film and is arranged opposite to the second light-exit surface. The principal optical axis of the first lens and the principal optical axis of the second lens are located on the same straight line. Light is reflected by the composite film, and after passing through the second lens and the first lens in sequence, part of the light is reflected by the composite film and emitted. The light beam undergoes two reflections and folds within the optical module, thereby shortening the length of the display module and solving the technical problem that existing optical systems cannot achieve both a large field of view and clear imaging in a small size.

Description

Technical Field

[0001] This application relates to the field of virtual reality technology, specifically to an optical module, an optical system, and a display device. Background Technology

[0002] With the development of virtual reality technology, the application scenarios of virtual reality devices are increasing. The principle is generally to use optical technology to guide the image light emitted by a miniature image display to the user's pupil, so as to achieve virtual imaging within the user's near field of vision.

[0003] Virtual reality devices are worn on the user's head, displaying miniature images in front of the user's eyes to create a virtual magnified image. The optical system used for display is the core of the head-mounted device, directly affecting important factors such as its size, weight, and visual experience. Most current head-mounted devices use Fresnel lenses to achieve virtual imaging, resulting in poor image clarity and a very large size, leading to a poor user experience. Some other head-mounted devices use multiple lens groups (usually five or more) to achieve virtual imaging. While the image clarity is relatively good, the large number of lenses, heavy weight, and limited field of view (only 50 degrees) result in poor immersion. Summary of the Invention

[0004] This application provides an optical module, an optical system, and a display device to solve the technical problem that existing optical systems cannot achieve both a large field of view and clear imaging in a small size.

[0005] This application provides an optical module, including a first lens, a second lens, and a composite film arranged sequentially. The first lens includes a first light-incident surface and a first light-outcident surface that are opposite to each other. The second lens includes a second light-incident surface and a second light-outcident surface that are opposite to each other. The second light-incident surface and the first light-outcident surface are arranged opposite to each other. The composite film includes a polarizing reflective film and a phase retarder. The phase retarder is attached to the polarizing reflective film and is arranged opposite to the second light-outcident surface. The principal optical axis of the first lens and the principal optical axis of the second lens are located on the same straight line. Light is reflected by the composite film, and after passing through the second lens and the first lens in sequence, part of the light is reflected by the composite film and emitted.

[0006] Optionally, the first lens is a concave lens; the first light-incident surface is a convex surface, and the first light-outceasing surface is a concave surface.

[0007] Optionally, the second lens is a convex lens, with both the second light-incident surface and the second light-outceasing surface being convex.

[0008] Optionally, the focal length of the first lens is f1, the focal length of the second lens is f2, and the total focal length of the optical module is f; then -6.0 <f1 / f<-1.2,1.1<f2 / f<5.0。

[0009] Optionally, the thickness of the first lens is t1, the thickness of the second lens is t2, and the total thickness of the optical module is T. Then 3.0mm < t1 < 6.0mm, 1.0mm < t2 < 4.0mm, and 0.1 < t1 / T < 0.3.

[0010] Optionally, the distance between the first lens and the second lens on the principal optical axis is t3. Then 0.05mm < t3 < 5.0mm.

[0011] Optionally, the optical module further includes a planar glass. The planar glass is disposed opposite to the second light-emitting surface, and the polarization reflection film is bonded to the planar glass.

[0012] Optionally, a beam splitting film layer is provided on the first light-incident surface.

[0013] Optionally, the optical module includes a mounting bracket, and the first lens, the second lens, and the planar glass are sequentially mounted to the mounting bracket.

[0014] Optionally, the mounting bracket includes an annular frame and three annular card slots. The annular card slots are recessed from the inner sidewall of the annular frame. The three annular card slots are the first card slot, the second card slot, and the third card slot in sequence. Among them, the edge of the first lens is snapped into the first card slot; the edge of the second lens is snapped into the second card slot; the edges of the planar glass and the composite film are snapped into the third card slot.

[0015] Correspondingly, the present application further provides an optical system, which includes an optical module, and the optical module is the optical module of any one of the above.

[0016] Optionally, the optical system further includes a display screen. The display screen is disposed opposite to the first light-incident surface and can be moved along the principal optical axis direction of the first lens.

[0017] Optionally, the distance between the display screen and the first lens is t4. Then 8.0mm < t4 < 12.0mm; the refractive power of the optical system is -7D - 0.

[0018] Optionally, when the distance between the display screen and the first lens increases by 0.4mm - 0.6mm, the refractive power of the optical system increases by 1D; when the distance between the display screen and the first lens decreases by 0.4mm - 0.6mm, the refractive power of the optical system decreases by 1D.

[0019] Correspondingly, the present application further provides a display device, which includes an optical system, and the optical system is the optical system of any one of the above.

[0020] This application provides an optical module, optical system, and display device. By utilizing a combination of a meniscus concave lens, a biconvex lens, and a composite film, the light beam undergoes two reflections and folds within the optical module, thereby shortening the length of the display module and making its structure more compact and lighter. Furthermore, since the first light-incident surface of the meniscus concave lens faces the light beam and the second light-outceasing surface of the biconvex lens faces the human eye, it is more conducive to reducing the size of the optical module. This allows for an increase in the effective field of view of the optical module within the same size, while also improving the phase aberration of the optical module. This is beneficial for achieving a high-resolution optical effect with uniform image quality across the entire frame, enhancing the immersive experience and comfort when wearing the device. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the optical path structure of the optical system provided in this application;

[0023] Figure 2 This is a modulation transfer function diagram of the optical system provided in this application;

[0024] Figure 3 These are the astigmatism and distortion curves of the optical system provided in this application;

[0025] Figure 4 This is a schematic diagram of the optical system provided in this application.

[0026] Explanation of reference numerals in the attached figures:

[0027] 10. Display screen; 20. First lens; 21. First light-incident surface; 22. First light-exit surface; 30. Second lens; 31. Second light-incident surface; 32. Second light-exit surface; 40. Composite film; 50. Flat glass; 60. Mounting bracket; 61. Annular frame; 62. First slot; 63. Second slot; 64. Third slot; 65. Fourth slot. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to up, down, left, and right in the actual use or working state of the device, specifically the drawing directions in the accompanying drawings.

[0029] This application provides an optical module, an optical system, and a display device, which are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0030] Please see Figures 1-4 This application provides an optical module comprising a first lens 20, a second lens 30, and a composite film 40 arranged sequentially along the optical path direction, wherein the principal optical axes of the first lens 20 and the second lens 30 are located on the same straight line. The first lens 20 includes a first incident surface 21 and a first exiting surface 22, wherein the first incident surface 21 faces the object side and the first exiting surface 22 faces the image side. In this application, the first lens 20 can be a meniscus concave lens. The first incident surface 21 is convex, and the first exiting surface 22 is concave; both the first incident surface 21 and the first exiting surface 22 are aspherical surfaces. The optical power of the first lens 20 is negative.

[0031] The second lens 30 includes a second light-incident surface 31 and a second light-exit surface 32. The second light-incident surface 31 is disposed opposite to the first light-exit surface 22, and the second light-exit surface 32 is convex. In this application, the second lens 30 can be a biconvex lens. The optical power value of the second lens 30 is positive, and both the second light-incident surface 31 and the second light-exit surface 32 are aspherical surfaces. In order to reduce the weight of the system, both the first lens 20 and the second lens 30 are made of plastic.

[0032] The composite film 40 includes a polarizing reflective film and a phase retarder. The polarizing reflective film is bonded to a plane, and the phase retarder is bonded to the polarizing reflective film, with the phase retarder positioned opposite to the second light-emitting surface 32. In this application, the phase retarder can be a quarter-wave plate. When light of a certain wavelength is incident perpendicularly through the quarter-wave plate, the phase difference between the emitted ordinary and extraordinary light is 1 / 4 wavelength, allowing for the conversion between circularly polarized (or elliptically polarized) light and linearly polarized light. The polarizing reflective film is used to reflect the portion of the light beam parallel to the reflection axis.

[0033] The light beam emitted by the light source is a left-handed elliptically polarized beam. After passing through the first lens 20, the second lens 30, and the quarter-wave plate, the left-handed elliptically polarized beam is converted into linearly polarized light. The linearly polarized light is parallel to the reflection axis of the polarizing reflective film, and is therefore reflected onto the quarter-wave plate, where it is converted into right-handed elliptically polarized light. After passing through the second lens 30 and the first lens 20, a portion of the right-handed elliptically polarized light is reflected again and passes through the quarter-wave plate, causing it to be converted into linearly polarized light. This linearly polarized light is perpendicular to the reflection axis of the polarizing reflective film, and is therefore received by the human eye after passing through the polarizing reflective film.

[0034] This application utilizes a combination of a first lens 20, a second lens 30, and a composite film 40 to cause the light beam to undergo two reflections and folds within the optical module, thereby shortening the length of the display module and making its structure more compact and lighter. Furthermore, since the first light-incident surface 21 of the first lens 20 faces the light beam and the second light-exit surface 32 of the second lens 30 faces the human eye, it is more advantageous to reduce the size of the optical module, increasing its effective field of view within the same size, while also improving the phase aberration of the optical module. This facilitates achieving a high-resolution optical effect with uniform image quality across the entire frame, enhancing the immersive experience and comfort when wearing the device.

[0035] Furthermore, the optical module also includes a planar glass 50, which is disposed opposite to the second light-emitting surface 32, and a polarizing reflective film is attached to the surface of the planar glass 50. In this application, the planar glass 50 has a spherical surface and its optical power is 0.

[0036] Furthermore, the focal length of the first lens 20 is f1, the focal length of the second lens 30 is f2, and the total focal length of the optical module is f; therefore, -6.0 <f1 / f<-1.2,1.1<f2 / f<5.0。

[0037] According to basic optical principles, the total focal length f of an optical module has the following fundamental relationship with the half-size d of the light beam and the half-field angle a:

[0038] tana = d / f

[0039] By reasonably designing the focal lengths of the first lens 20 and the second lens 30, the total focal length f of the optical module is reduced, so that the effective viewing angle of the optical module can be increased under the same size.

[0040] The above-mentioned value ranges of f1 / f and f2 / f are closely related to the correction of the aberration of the optical module, the processing difficulty of the optical elements, and the sensitivity of the assembly deviation of the optical elements, enabling the aberration of the optical module to be fully corrected, thereby achieving excellent optical effects and improving the processability of the optical elements in the optical module.

[0041] Furthermore, the thickness of the first lens 20 is t1, the thickness of the second lens 30 is t2, and the total thickness of the optical module is T. Then 3.0mm < t1 < 6.0mm, 1.0mm < t2 < 4.0mm, and 0.1 < t1 / T < 0.3.

[0042] The above-mentioned value ranges of t1, t2, and t1 / T are closely related to the correction of the aberration of the optical module, the processing difficulty of the optical elements, and the sensitivity of the assembly deviation of the optical elements, enabling the aberration of the optical module to be fully corrected, thereby achieving excellent optical effects and improving the processability of the optical elements in the optical module.

[0043] Furthermore, in the present application, the distance between the first lens 20 and the second lens 30 along the principal optical axis is t3, and 0.05mm < t3 < 5.0mm.

[0044] By limiting the distance between the first lens 20 and the second lens 30, the total focal length of the optical module in the present application can be further limited, thereby further increasing the effective viewing angle of the optical module.

[0045] Table 1: Parameters of each optical element:

[0046]

[0047] Table 2: Parameters of the first lens 20 and the second lens 30:

[0048]

[0049]

[0050] As can be seen from Table 1 and Table 2 above, when the specific parameters of the first incident surface 21 and the first exit surface 22 of the first lens 20 are set as shown in Table 1 and Table 2, the focal length of the first lens 20 is -88.41mm. At the same time, when the specific parameters of the second incident surface 31 and the second exit surface 32 of the second lens 30 are set as shown in Table 1 and Table 2, the focal length of the second lens 30 is 59.04mm.

[0051] Combined with Figure 1 The optical path structure diagram shown depicts a first lens 20, a second lens 30, and a composite film 40 arranged sequentially along the optical path direction. Based on the parameter selections of the first lens 20, the second lens 30, and the composite film 40 in Tables 1 and 2, the field of view of the optical module in this embodiment is 100 degrees, the total length is 21.1 mm, and the total focal length is 22.7 mm.

[0052] Furthermore, a beam-splitting film layer is deposited on the first light-receiving surface 21.

[0053] Furthermore, refer to Figure 4 The optical module also includes a mounting bracket 60, on which the first lens 20, the second lens 30, and the planar glass 50 are sequentially mounted. The mounting bracket 60 secures the first lens 20, the second lens 30, and the planar glass 50, ensuring that the distance and position between them remain unchanged during use, thereby improving the reliability of the optical module.

[0054] Furthermore, the mounting bracket 60 includes an annular frame 61 and three annular slots, all of which are recessed into the inner wall of the annular frame 61. In this application, the three annular slots are, in order, a first slot 62, a second slot 63, and a third slot 64. Specifically, the edge of the first lens 20 engages with the first slot 62; the edge of the second lens 30 engages with the second slot 63; and the edges of the planar glass 50 and the composite film 40 engage with the third slot 64.

[0055] The width and spacing of the first slot 62, the second slot 63, and the third slot 64 are designed based on the thickness of the first lens 20, the second lens 30, and the planar glass 50, as well as their spacing. The first slot 62 is used to embed and fix the first lens 20, the second slot 63 to embed and fix the second lens 30, and the third slot 64 to embed and fix the planar glass 50 and the composite film 40. Therefore, by fixing the first lens 20, the second lens 30, and the planar glass 50 respectively, the positions and spacing of the first lens 20, the second lens 30, and the planar glass 50 in the optical module remain unchanged during use, thereby improving the reliability and stability of the optical module.

[0056] In other embodiments of this application, an optical system is disclosed, which includes an optical module and the structure of the optical module is consistent with the structure of the optical module described above. Therefore, its structure can be referred to the structure of the aforementioned optical module, and will not be described in detail here.

[0057] Furthermore, the aforementioned optical system also includes a display screen 10, which is disposed opposite to the first light-incident surface 21 and is movable along the principal optical axis of the first lens 20. In this application, the display screen 10 is the screen of an organic electroluminescent device, a transmissive liquid crystal display, or a reflective liquid crystal display. The optical system forms a virtual magnified image from the image on the display screen 10 through an optical module and displays it in front of a person's eyes.

[0058] In this application, the display screen 10 is positioned opposite to the first light-incident surface 21. Therefore, the left-handed elliptically polarized light emitted by the display screen 10 can be sequentially converted into linearly polarized light after passing through the first lens 20, the second lens 30, and the quarter-wave plate. This linearly polarized light is parallel to the reflection axis of the polarizing reflective film, and is thus reflected onto the quarter-wave plate, where it is converted into right-handed elliptically polarized light. After passing through the second lens 30 and the first lens 20, a portion of the right-handed elliptically polarized light is reflected again and passes through the quarter-wave plate, converting it into linearly polarized light. This linearly polarized light is perpendicular to the reflection axis of the polarizing reflective film, and is thus received by the human eye after passing through the polarizing reflective film.

[0059] Because the display screen 10 can be moved along the principal optical axis of the first lens 20, the distance between the display screen 10 and the first lens 20 is changed, thereby changing the diopter of the optical system. By changing the distance between the display screen 10 and the first lens 20, the user can adjust the diopter of the optical system to a matching value to match the user's vision.

[0060] Existing technologies typically adjust the diopter of an optical system by moving the lens to change the focal length, thus matching users with different degrees of myopia. In this application, the diopter of the optical system is changed by moving the display screen 10 along the principal optical axis of the first lens 20, thereby adjusting the distance between the display screen 10 and the first lens 20. Therefore, the focal length of the optical system is not changed while adjusting the diopter, giving this application a significant advantage in performance improvement.

[0061] In this application, the annular frame 61 is further provided with a fourth slot 65, which is recessed into the inner sidewall of the annular frame 61. The edge of the display screen 10 is engaged with the fourth slot 65. The width and spacing of the fourth slot 65 are designed according to the thickness of the display screen 10 and the distance between the display screen 10 and the first lens 20. Since the display screen 10 can move relative to the first lens 20, an adjustment member is provided on the annular frame 61 to help limit the position of the display screen 10 relative to the first lens 20.

[0062] Furthermore, there is an air medium between the display screen 10 and the first lens 20, and the distance between the display screen 10 and the first lens 20 is t4. Then 8.0mm < t4 < 12.0mm; the corresponding refractive power of the optical system is -7D-0.

[0063] Table 3 shows the correspondence between the distance between the display screen 10 and the first lens 20 and the degree of myopia:

[0064] Corresponding myopia 0D -1D -2D -3D -4D -5D -6D -7D Spacing between screen and first lens 11.57 11.04 10.55 10.08 9.63 9.16 8.77 8.27

[0065] According to Table 3, the adjustment range of the distance t4 between the display screen 10 and the first lens 20 in this application is 8.0mm < t4 < 12.0mm; the corresponding refractive power of the optical system is -7D-0. Therefore, by moving the display screen 10 within the preset range of this application, the optical system in this application can be adapted to users with myopia up to 700 degrees.

[0066] Furthermore, when the distance between the display screen 10 and the first lens 20 increases by 0.4mm-0.6mm, the diopter of the optical system increases by 1D; when the distance between the display screen 10 and the first lens 20 decreases by 0.4mm-0.6mm, the diopter of the optical system decreases by 1D.

[0067] According to Table 3, the distance t4 between the display screen 10 and the first lens 20 is positively correlated with the diopter (myopia) of the optical system. Therefore, when the distance between the display screen 10 and the first lens 20 increases, the diopter of the optical system increases, making the optical system suitable for users with lower myopia. Conversely, when the distance between the display screen 10 and the first lens 20 decreases, the diopter of the optical system decreases, making the optical system suitable for users with higher myopia. In this application, when the distance between the display screen 10 and the first lens 20 increases by 0.4mm-0.6mm, the diopter of the optical system increases by 1D; when the distance between the display screen 10 and the first lens 20 decreases by 0.4mm-0.6mm, the diopter of the optical system decreases by 1D. By limiting the change in diopter corresponding to the distance the display screen 10 moves to intersect with the meniscus lens, it is easier for the user to adjust the diopter while wearing the device.

[0068] In other embodiments of this application, a display device is also provided, which is a head-mounted display device. The display device includes an optical system, and the structure of the optical system is consistent with the structure of the optical system in the aforementioned scheme. For details, please refer to the structure of the aforementioned optical system, which will not be repeated here.

[0069] The foregoing has provided a detailed description of an optical module, optical system, and display device provided by this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An optical module, characterized in that, Including those arranged in sequence: The first lens includes a first light-incident surface and a first light-outceasing surface. The first lens is a concave lens. The first light-incident surface is a convex surface, the first light-outceasing surface is a concave surface, and the first lens is a plastic lens. A beam-splitting film layer is provided on the first light-incident surface. A second lens, comprising a second light-incident surface and a second light-outcident surface; the second light-incident surface is disposed opposite to the first light-outcident surface; the second lens is a convex lens; both the second light-incident surface and the second light-outcident surface are convex surfaces; both the second light-incident surface and the second light-outcident surface are aspherical surfaces; and the second lens is a plastic lens; A composite film, comprising a polarizing reflective film and a phase retardation film, wherein the phase retardation film is attached to the polarizing reflective film and is disposed opposite to the second light-emitting surface; Wherein, the principal optical axis of the first lens and the principal optical axis of the second lens are on the same straight line; the light is reflected by the composite film, and after passing through the second lens and the first lens in sequence, part of the light is reflected by the beam-splitting film layer on the first light-incident surface and emitted; The thickness of the first lens is t1, and the thickness of the second lens is t2, then it is 3.0 mm. <t1<6.0mm,1.0mm<t2<4.0mm; The focal length of the first lens is f1, the focal length of the second lens is f2, and the total focal length of the optical module is f; then -6.0 <f1 / f<-1.2,1.1<f2 / f<5.0。 2. The optical module according to claim 1, characterized in that, The total thickness of the optical module is T, then 0.1 <t1 / T<0.3。 3. The optical module according to claim 2, characterized in that, The distance between the first lens and the second lens on the principal optical axis is t3, then 0.05mm <t3<5.0mm。 4. The optical module according to claim 1, characterized in that, Also includes: A flat glass surface is disposed opposite to the second light-emitting surface, and the polarizing reflective film is attached to the flat glass surface.

5. The optical module according to claim 4, characterized in that, It also includes mounting brackets; The first lens, the second lens, and the flat glass are sequentially mounted onto the mounting bracket.

6. The optical module according to claim 5, characterized in that, The mounting bracket includes: Ring frame; Three annular slots are recessed into the inner wall of the annular frame, and the three annular slots are sequentially designated as a first slot, a second slot, and a third slot; wherein, The edge of the first lens engages with the first slot. The edge of the second lens engages with the second slot; The edges of the flat glass and the composite film are engaged into the third slot.

7. An optical system, characterized in that, Includes the optical module according to any one of claims 1-6; The display screen is disposed opposite to the first light-incident surface and is movable along the principal optical axis of the first lens; If the distance between the display screen and the first lens is t4, then 8.0mm < t4 < 12.0mm; The optical system has a refractive power ranging from -7D to 0; When the distance between the display screen and the first lens increases by 0.4mm-0.6mm, the diopter of the optical system increases by 1D; When the distance between the display screen and the first lens decreases by 0.4mm-0.6mm, the diopter of the optical system decreases by 1D.

8. A display device, characterized in that, Includes the optical system described in claim 7.

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