Optical modules and head-mounted display devices

Abstract

The present application discloses an optical module and a head-mounted display device; wherein the optical module includes a curved screen, at least one lens, a beam splitter, a phase retarder and a polarized reflective element; the curved screen is used to emit light, and the curvature direction of the curved screen is toward the propagation direction of the light; the at least one lens is located in the light emitting direction of the curved screen; the phase retarder is located between the beam splitter and the polarized reflective element, and the at least one lens is located between the beam splitter and the polarized reflective element; the curvature radius of the curved screen is R, the luminous radius of the curved screen is I, and the field curvature correction value of the optical module is V, then R, I, and V satisfy the following conditions: 0 <R‑(R 2 ‑I 2 ) 0.5

Description

Technical Field

[0001] The present application relates to the field of optical structure technology, and more specifically, to an optical module and a head-mounted display device. Background Art

[0002] VR optical systems utilize the optical properties of optical devices to magnify displayed images at short distances, achieving an immersive visual experience for users. As VR display panel resolution continues to increase, a high-quality user experience demands a simultaneous increase in optical system resolution. Improving optical system resolution at the edge of the eyebox and at wide fields of view requires even greater aberration correction capabilities. Field curvature aberrations are a function of field of view and cannot be corrected through post-modulation of image data; they can only be corrected within the optical structure design. Therefore, field curvature correction is a significant factor limiting improvements in optical system imaging quality. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for an optical module and a head-mounted display device, which can improve the imaging quality of the optical module while achieving field curvature correction.

[0004] An embodiment of the present application provides an optical module, comprising:

[0005] a curved screen, the curved screen being used to emit light, wherein the curvature direction of the curved screen is toward the propagation direction of the light;

[0006] at least one lens, the at least one lens being located in a light-emitting direction of the curved screen;

[0007] A beam splitter, a phase retarder, and a polarized reflective element, wherein the phase retarder is located between the beam splitter and the polarized reflective element, and the at least one lens is located between the beam splitter and the polarized reflective element;

[0008] The curvature radius of the curved screen is R, the luminous radius of the curved screen is I, and the field curvature correction value of the optical module is V. Then R, I, and V satisfy:

[0009] 0 <R-(R 2 -I 2 ) 0.5 <V<0.3mm。

[0010] Optionally, when the optical module includes a lens, when the eyebox is ≥8 mm and the field of view angle is ≥90°:

[0011] The total optical length of the optical module is TL1, the aperture of the lens is D1, and the ratio of TL1 to D1 satisfies: 0.5<TL1 / D1<0.9;

[0012] The effective focal length EFL1 of the optical module is: 14.5 mm < EFL1 < 18.5 mm.

[0013] Optionally, when the optical module includes two or more lenses, when the eyebox is ≥8 mm and the field of view angle is ≥90°:

[0014] The total optical length of the optical module is TL2, the diameter of the largest lens in the optical module is D2, and the ratio of TL2 to D2 satisfies: 0.2<TL2 / D2<0.9;

[0015] The effective focal length EFL2 of the optical module is: 11.5 mm < EFL2 < 25.5 mm.

[0016] Optionally, the lens with the largest aperture is the first lens or the second lens close to the curved screen.

[0017] Optionally, the at least one lens includes a first lens and a second lens, wherein the beam splitter is located on a surface of the first lens close to the curved screen, the phase delay is located on a surface of the first lens away from the curved screen, and the polarized reflection element is located on a surface of the second lens close to the curved screen.

[0018] Optionally, the angle between the fast axis direction of the phase retarder and the transmission axis direction of the polarized reflective element is 45 degrees;

[0019] The polarization reflecting element is capable of reflecting one of horizontally polarized light and vertically polarized light and transmitting the other of the horizontally polarized light and vertically polarized light.

[0020] Optionally, the optical module further includes a polarization element, and the polarization element is located on a side of the polarization reflection element away from the phase retarder.

[0021] Optionally, the polarizing element and the polarized reflecting element are stacked together to form a stacked element, and the polarization direction of the polarizing element is the same as the polarization transmission direction of the polarized reflecting element.

[0022] Optionally, the optical module further includes a screen protection sheet, which is provided on the light-emitting surface of the curved screen, and the curvature radius of the screen protection sheet is the same as the curvature radius of the curved screen.

[0023] The present embodiment provides a folded optical path solution based on a curved screen. This solution incorporates a curved screen into an optical module. By controlling the curvature radius R of the curved screen, the luminous radius I of the curved screen, and the field curvature correction value V of the optical module, the three parameters are kept within a predetermined range. This reduces the performance sacrificed by the optical module to correct for field curvature, improves the resolution of the optical module, and enhances the imaging quality of the optical module. This optical solution provides greater freedom in optical design.

[0024] Applying the optical module of the embodiment of the present application to a head-mounted display device can make the head-mounted display device have the performance advantages of being light and thin, having a large field of view and high resolution.

[0025] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0027] Figure 1 This is one of the structural diagrams of the optical module provided in the embodiment of the present application;

[0028] Figure 2 This is the field curvature diagram of the optical module of the flat screen

[0029] Figure 3 It is the field curvature diagram of the optical module of the curved screen;

[0030] Figure 4 2. This is a schematic diagram showing the principle of increasing the light emission angle at the edge of a curved screen in an embodiment of the present application;

[0031] Figure 5 This is the second structural diagram of the optical module provided in the embodiment of the present application;

[0032] Figure 6 is the MTF curve of the central eyebox provided in Example 1 of the present application;

[0033] Figure 7 is the MTF curve of the edge eyebox provided in Example 1 of the present application;

[0034] Figure 8 is the field curvature curve of the edge eyebox provided in Example 1 of the present application;

[0035] Figure 9 is the MTF curve of the central eyebox provided in Example 2 of the present application;

[0036] Figure 10 is the MTF curve of the edge eyebox provided in Example 2 of the present application;

[0037] Figure 11 is the field curvature curve of the edge eyebox provided in Example 2 of the present application;

[0038] Figure 12 is the MTF curve of the central eyebox provided in Example 3 of the present application;

[0039] Figure 13 is the MTF curve of the edge eyebox provided in Example 3 of the present application;

[0040] Figure 14 It is the field curvature curve of the edge eyebox provided in Example 3 of the present application.

[0041] Description of reference numerals:

[0042] 10. First lens; 20. Second lens; 30. Beam splitter; 40. Phase retarder; 50. Polarization reflector; 60. Polarization element; 70. Curved screen; 80. Screen protector; 01. Aperture; 02. Flat screen. DETAILED DESCRIPTION

[0043] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application.

[0044] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0045] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0046] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0047] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0048] The following is combined with Figures 1 to 14 The optical module and head-mounted display device provided in the embodiments of the present application are described in detail.

[0049] According to one aspect of an embodiment of the present application, an optical module is provided. The optical module has a folded optical path design and is suitable for application in a head mounted display (HMD), such as VR smart glasses.

[0050] The optical module of the embodiment of the present application is as follows: Figure 1 As shown, the optical module includes: a curved screen 70, at least one lens, a beam splitter 30, a phase retarder 40, and a polarized reflective element 50; the curved screen 70 is used to emit light, and the curvature of the curved screen 70 is toward the propagation direction of the light; the at least one lens is located in the light emitting direction of the curved screen 70; the beam splitter 30, the phase retarder 40, and the polarized reflective element 50, wherein the phase retarder 40 is located between the beam splitter 30 and the polarized reflective element 50, and the at least one lens is located between the beam splitter 30 and the polarized reflective element 50;

[0051] The curvature radius of the curved screen 70 is R, the luminous radius of the curved screen 70 is I, and the field curvature correction value of the optical module is V. Then R, I, and V satisfy:

[0052] 0 <R-(R 2 -I 2 ) 0.5 <V<0.3mm。

[0053] In the optical module of the embodiment of the present application, the display has a curved structure, that is, the optical module adopts a curved screen 70 , and the light emitting surface of the curved screen 70 has a certain curvature radius.

[0054] Improving optical module resolution at the edge of the eyebox (e.g., eyebox ≥ 8mm) and with a wide field of view requires a high level of aberration correction. Field curvature aberration, a function of field of view, cannot typically be corrected through post-modulation of image data and can only be corrected within the optical structure design. Field curvature correction is a significant factor limiting improvements in optical module imaging quality.

[0055] It should be noted that in the related art, the method for correcting the field curvature of the optical module generally includes: first, separating the positive and negative lens groups; second, adjusting the refractive index of the positive and negative lenses; and third, adding a thick meniscus lens. In order to meet the design requirements of lightweight VR devices, one to three injection-molded lenses are usually used in the folding optical module. However, due to the limited refractive index of the injection-molded lenses, the second method mentioned above has greater limitations. The first and third methods mentioned above usually limit the structure of the optical module. It can be seen that the existing solutions will affect the further improvement of the resolution of the optical module.

[0056] The optical solution provided by the embodiments of the present application creatively discovers that by introducing a curved screen 70 into the optical module, and simultaneously adjusting the curvature radius R and the emission radius I of the curved screen 70, as well as the field curvature correction value V of the optical module, and making the above three values of R, I, and V satisfy: 0 < R - (R 2 - I 2 ) 0 . 5 < V < 0.3 mm within this limited range, it is possible to reduce the field curvature of the optical module while improving the resolution of the optical module. Furthermore, it is possible to improve the imaging quality of the optical module.

[0057] It should be noted that when the curvature radius of the curved screen 70 is small, if the field curvature correction value V is designed too large, it will limit the design freedom of the optical module; while when the curvature radius of the curved screen 70 is large, it will lead to the inability to meet the purpose of the field curvature correction auxiliary design. At this time, the structural advantages of the curved screen 70 are difficult to demonstrate. Based on this, in the optical module of the embodiments of the present application, the curvature radius R and the emission radius I of the curved screen 70, as well as the field curvature correction value V of the optical module are controlled, so that the three need to satisfy: 0 < R - (R 2 - I 2 ) 0.5 < V < 0.3 mm. Such a design can reduce the performance sacrificed by the optical module to correct its own field curvature, improve the resolution of the optical module, and further improve the imaging quality of the optical module.

[0058] Figure 2 shows the field curvature diagram of the optical module using a flat screen, Figure 3 shows the field curvature diagram of the optical module using a curved screen. According to Figure 2 and Figure 3 in the comparison, it can be seen that for the optical module using the curved screen 70 ( Figure 3 shown, that is, the solution of the present application) and the optical module using a flat screen ( Figure 2 shown, the traditional solution), the field curvature of the optical module with the curved screen 70 changes more smoothly within the entire viewing field, the curve fluctuation is smaller, and the field curvature at the maximum viewing field of the eyebox edge is smaller. While Figure 3 the field curvature curve shown in is significantly more fluctuating.

[0059] For example, Figure 2 shows that the maximum field curvature of the optical module with a flat screen is 0.24 μm, and the minimum field curvature is 0.07 μm. Figure 3 shows that the maximum field curvature of the optical module with a curved screen is 0.21 μm, and the minimum field curvature is 0.06 μm. It can be shown that the optical solution provided by the embodiments of the present application can reduce the field curvature of the optical module.

[0060] In the optical module of the embodiment of the present application, the curved screen 70 provides greater freedom in optical structural design. Compared to traditional flat screens, designing a curved screen 70 with a certain radius of curvature within the optical module effectively compensates for the field curvature of the optical module. It also increases the luminous angle at the edge of the screen, improving the efficiency of light utilization at the edge of the screen. The optical solution of the present application facilitates the design of optical modules with wide fields of view and large eyeboxes. It not only improves the imaging quality of the optical module but also helps reduce the processing sensitivity of the lens.

[0061] For example, Figure 4 As shown, assuming the single-pixel luminous angle is θ, the luminous angle of flat screen 02 is -0.5θ to 0.5θ. Assuming the effective luminous size of curved screen 70 is L and the radius of curvature of curved screen 70 is R, the luminous angle of curved screen 70 is -β-0.5θ to β+0.5θ, where β = arcsin(0.5L / R). The luminous angle of the increased light at the edge of curved screen 70 is β = arcsin(0.5L / R).

[0062] Specifically, compared with the flat screen 02 , when θ=30°, L=24 mm, and R is between 20 mm and 1000 mm, the luminous angle β of the edge light of the curved screen 70 increases to 0.6° to 3.5°.

[0063] That is to say, when the luminous angle of the light-emitting surface of the screen remains unchanged, the curved screen 70 with the same radial size increases the luminous angle of the screen edge compared to the flat screen 02, thereby improving the utilization efficiency of the light at the edge of the screen. Therefore, for optical modules with small-size, high-resolution screens, the curved screen design has significant advantages.

[0064] The present embodiment provides a folded optical path solution based on a curved screen. The curved screen 70 is introduced into the optical module. By controlling the curvature radius R of the curved screen 70, the luminous radius I of the curved screen 70, and the field curvature correction value V of the optical module, the three parameters are controlled to fall within a predetermined range. This reduces the performance sacrificed by the optical module to correct for field curvature, improves the resolution of the optical module, and enhances the imaging quality of the optical module. The optical solution of the present application can enrich the degrees of freedom of optical design.

[0065] Applying the optical module of the embodiment of the present application to a head-mounted display device can make the head-mounted display device have the performance advantages of being light and thin, having a large field of view and high resolution.

[0066] In the optical module of the embodiment of the present application, the number of lenses provided can be one, two, or three or more, and can be flexibly adjusted according to specific needs. There is no limitation on this in the embodiment of the present application.

[0067] In the optical module of the present embodiment, the surface shape of each lens can also be designed as needed. The lens surface shape can include, for example, plane, spherical, aspherical, Fresnel, free-form, and other surface shapes. This can enrich the degree of freedom in optical module design.

[0068] In some examples of the present application, when the optical module includes a lens, when the eyebox eyebox ≥ 8 mm and the field of view angle ≥ 90°: the total optical length of the optical module is TL1, the aperture of the lens is D1, and the ratio of TL1 to D1 satisfies: 0.5<TL1 / D1<0.9; the effective focal length EFL1 of the optical module is: 14.5 mm<EFL1<18.5 mm.

[0069] For example, when only one lens is provided in the optical module of the present application, the beam splitter 30 can be disposed on the surface of the lens close to the curved screen 70, and the phase retarder 40 and the polarizing reflective element 50 can be bonded together and disposed on the surface of the lens away from the curved screen 70. In this case, on one side of the aperture 01, when the eyebox is ≥ 8 mm and the field of view is large, such as when the field of view is 90° or greater, the ratio of the total optical length TL1 of the optical module to the aperture D1 of the lens is controlled to be within the range of 0.5 to 0.9, and the effective focal length of the optical module is set to be between 14.5 mm and 18.5 mm. In combination with the curved screen 70, the field curvature of the optical module can be better reduced and the resolution can be improved within a larger field of view, thereby making the optical module compact, thin, and lightweight while also having excellent imaging quality.

[0070] It should be noted that when the field of view of the optical module of the present application is adjusted to a large value (for example, above 130°), since there is only one lens in the module, the total length of the optical module system may increase, thereby increasing the maximum value of TL1 / D1.

[0071] When the field of view of the optical module is greater than or equal to 90°, it is more preferred that the value of TL1 / D1 is in the range of 0.5 to 0.75, which is suitable for most optical modules.

[0072] In some examples of the present application, when the optical module includes two or more lenses, when the eyebox is ≥8mm and the field of view angle is ≥90°: the total optical length of the optical module is TL2, the aperture of the lens with the largest aperture in the optical module is D2, and the ratio of TL2 to D2 satisfies: 0.2<TL2 / D2<0.9; the effective focal length EFL2 of the optical module is: 11.5mm<EFL2<25.5mm.

[0073] For example, when two lenses are provided in the optical module of the present application, Figure 1 As shown, the two lenses are a first lens 10 and a second lens 20. The first lens 10 is arranged close to the curved screen 70, and the second lens 20 is arranged away from the curved screen 70. On this basis, the beam splitter 30 can be arranged on the surface of the first lens 10 close to the curved screen 70, the phase retarder 40 can be arranged on the surface of the first lens 10 away from the curved screen 70, and the polarizing reflective element 50 can be arranged on the surface of the second lens 20 close to the curved screen 70. At this time, on one side of the aperture 01, when the eyebox eyebox is ≥ 8 mm and the field of view is large, for example, when the field of view is 90° or larger, the ratio of the total optical length TL2 of the optical module to the diameter D2 of the largest lens among the first lens 10 and the second lens 20 is controlled to be set within the range of 0.2 to 0.9, and the effective focal length of the optical module is set to be between 11.5 mm and 25.5 mm. In this way, combined with the introduction of the curved screen 70, the multi-lens optical module can greatly reduce the field curvature of the optical module and greatly improve the resolution within a larger field of view, and can also make the optical module small in size, light and thin while having excellent imaging quality.

[0074] It should be noted that, in the above example, the number of lenses is not limited to two, and an optical structure of three lenses may also be employed.

[0075] Optionally, the lens with the largest aperture is the first lens or the second lens close to the curved screen 70 .

[0076] By placing the lens with a relatively large aperture as close as possible to the curved screen 70 , as much light emitted from the curved screen 70 as possible can enter the optical module, thereby improving light utilization.

[0077] For example, Figure 1 As shown, the optical module includes a first lens 10 and a second lens 20. The first lens 10 is close to the curved screen 70, and the second lens 20 is far away from the curved screen 70. Therefore, the aperture of the first lens 10 can be designed to be larger than the aperture of the second lens 20. In this optical module, the first lens 10 is the lens with the largest aperture.

[0078] In some examples of this application, such as Figure 1 As shown, the optical module includes at least one lens, and the at least one lens includes a first lens 10 and a second lens 20, wherein the beam splitter 30 is arranged on the surface of the first lens 10 close to the curved screen 70, the phase retarder 40 is arranged on the surface of the first lens 10 away from the curved screen 70, and the polarized reflection element 50 is located on the surface of the second lens 20 close to the curved screen 70.

[0079] The optical module of the embodiment of the present application may include two optical lenses, namely the first lens 10 and the second lens 20 mentioned above. The number of optical lenses is small, which can reduce the assembly difficulty and the size of the optical module, while ensuring good imaging quality.

[0080] like Figure 1 As shown, the first lens 10 may be located on a side close to the curved screen 70 , and the second lens 20 may be located on a side away from the curved screen 70 .

[0081] The optical module provided in the embodiment of the present application, in addition to the two optical lenses mentioned above, also includes a polarized reflective element 50, a phase retarder 40, and a beam splitter 30, thereby forming a folded optical path. The individual optical lenses and optical elements in the optical module can be arranged in a predetermined manner and located on the same optical axis. The entire optical path structure is small in size and does not occupy a large space. It is very suitable for application in smart wearable devices, such as head-mounted display devices.

[0082] The light splitting element 30 is, for example, a semi-reflective and semi-transmissive film, which can be directly formed on the surface of the first lens 10 close to the curved screen 70 by coating.

[0083] In the embodiment of the present application, the beam splitter 30 can transmit a portion of light and reflect a portion of light.

[0084] It should be noted that the reflectivity of the light-splitting element 30 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0085] The phase retarder 40 is, for example, a quarter wave plate or other phase retarder. In this case, the phase retarder 40 can be directly mounted on the surface of the first lens 10 away from the curved screen 70 .

[0086] The polarized reflective element 50 is, for example, a polarized reflective film. In this case, the polarized reflective element 50 can be directly attached to the surface of the second lens 20 close to the curved screen 70 .

[0087] It should be noted that the phase retarder 40 and the polarized reflective element 50 can be arranged adjacent to each other and spaced apart. Of course, the phase retarder 40 and the polarized reflective element 50 can also be directly mounted together, which is not limited in the embodiment of the present application.

[0088] The beam splitter 30 , the phase retarder 40 and the polarization reflective element 50 are mounted on the surfaces of different lenses, thereby reducing the difficulty of assembling the optical module and saving costs.

[0089] In addition, it should be noted that in the optical module, the spectrometer element 30, the phase delay element 40 and the polarization reflection element 50 can be independent optical devices arranged at appropriate positions in the optical path structure, and are not limited to the above-mentioned coating or the design of being mounted on the corresponding lens. This is not limited in the embodiments of the present application.

[0090] In the embodiment of the present application, the angle between the fast axis of the phase retarder 40 and the transmission axis of the polarizing reflective element 50 is 45 degrees. The polarizing reflective element 50 can reflect one of horizontally polarized light and vertically polarized light and transmit the other of the horizontally polarized light and vertically polarized light.

[0091] The phase retarder 40 can be used to change the polarization state of light in the folded optical path structure, for example, to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0092] The polarized reflective element 50 may be a polarized reflective device that can reflect linearly polarized light at any other specific angle and transmit linearly polarized light in a direction perpendicular to the angle.

[0093] In the embodiment of the present application, the phase retarder 40 cooperates with the polarization reflection element 50 to analyze and transmit the light.

[0094] The beam splitter 30 , the phase retarder 40 and the polarization reflection element 50 may be provided on any one of a plane, a spherical surface, an aspherical surface, a free-form surface or a cylindrical surface.

[0095] In some examples of the present application, the optical module further includes a polarization element 60 , and the polarization element 60 is located on a side of the polarization reflection element 50 away from the phase retarder 40 .

[0096] The polarizing element 60 can be used to reduce stray light caused by the polarization reflectivity of the polarizing reflective element 50 not being 100%, thereby improving the imaging quality of the optical module.

[0097] The polarizer 60 has a transmission axis. The angle between the transmission axis of the polarizer 60 and the fast axis of the phase retarder 40 is 45°; this angle can be either positive or negative. The phase retarder 40 has a fast axis and a slow axis. Light oriented in the same direction as the transmission axis of the polarizer 60 can pass through the polarizer 60, while light oriented perpendicular to the transmission axis cannot.

[0098] In some examples of this application, such as Figure 1 As shown, the polarizing element 60 and the polarizing reflecting element 50 can be stacked together to form a stacked element, and the polarization direction of the polarizing element 60 is the same as the polarization transmission direction of the polarizing reflecting element 50 .

[0099] The polarizing reflective element 50 can reflect linearly polarized light in the horizontal and vertical directions while transmitting linearly polarized light in the vertical and horizontal directions. The optical module of the present application incorporates a polarizing element 60, such as a polarizing plate, which can be laminated with the polarizing reflective element 50 to form a laminated element and mounted, for example, on the surface of the second lens 20 near the curved screen 70. This simplifies the assembly of the polarizing element 60 within the optical path.

[0100] In the stacked element, the polarization direction of the polarizing element 60 is the same as the polarization transmission direction of the polarizing reflective element 50 . The polarizing element 60 can be used to reduce stray light caused when the polarization reflectivity of the polarizing reflective element 50 is not 100%, thereby improving imaging quality.

[0101] In some examples of this application, such as Figure 1 As shown, the optical module further includes a screen protection sheet 80 , which is disposed on the light-emitting surface of the curved screen 70 . The curvature radius of the screen protection sheet 80 is the same as that of the curved screen 70 .

[0102] It can be understood that the curved screen 70 has a certain curvature radius. When the screen protection sheet 80 is attached to the light emitting surface thereof, the screen protection sheet 80 should have the same curvature radius as that of the curved screen 70 .

[0103] Optionally, the light emitted by the curved screen 70 may be linearly polarized light, circularly polarized light, or natural light, which is not limited in the embodiment of the present application.

[0104] Optionally, the curved screen 70 may be an OLED flexible screen, a MicroOLED curved screen, a backlight curved screen, or any other display screen that can make the light-emitting surface into a rotationally symmetrical structure.

[0105] The optical module provided in the embodiment of the present application is as follows: Figure 1 As shown, the propagation process of light is as follows:

[0106] Left-handed circularly polarized light is emitted from the curved screen 70, passes through the screen protector 80, the beam splitter 30, the first lens 10, and the phase retarder 40, and is converted into horizontally / vertically linearly polarized light. It is then reflected by the superimposed element formed by the polarizing reflective element 50 with vertical / horizontal polarization and the polarizing element 60. It is then converted into left-handed circularly polarized light by the phase retarder 40. It is then reflected by the first lens 10 and the beam splitter 30 and converted into right-handed circularly polarized light. It is then converted into vertically / horizontally linearly polarized light by passing through the first lens 10 and the phase retarder 40 again. It then passes through the superimposed element and the second lens 20 before entering the aperture 01 to form an image.

[0107] In addition, when the light emitted from the light exiting surface of the curved screen 70 is linearly polarized light, another phase retarder may be provided between the light exiting surface of the curved screen 70 and the first lens 10 to convert the linearly polarized light into circularly polarized light.

[0108] The optical module of the embodiment of the present application can be applied to virtual reality pancake optical modules, virtual reality Fresnel optical modules and other application types of optical modules with large eye boxes and large field of view, and has a wide range of applications.

[0109] Example 1

[0110] like Figure 5 As shown, the optical module of this embodiment 1 includes: a curved screen 70, a first lens 10 and a second lens 20, a beam splitter 30, a phase retarder 40, a polarizing reflective element 50, and a polarizing element 60; the curved screen 70 is used to emit light, with the curvature of the curved screen 70 facing the propagation direction of the light; a screen protection sheet 80 is provided on the light emitting surface of the curved screen 70; the first lens 10 and the second lens 20 are located in the light emitting direction of the curved screen 70;

[0111] The beam splitter 30 is disposed on the surface of the first lens 10 close to the curved screen 70 , the phase retarder 40 is disposed on the surface of the first lens 10 away from the curved screen 70 , and the polarizing reflective element 50 is located on the surface of the second lens 20 close to the curved screen 70 ;

[0112] The first lens 10 and the second lens 20 are both aspherical lenses. The surface S1 of the second lens 20 near the aperture 01 is a convex aspherical surface, while the surface S2 of the distant aperture 01 is a concave aspherical surface. The surface S1 of the first lens 10 near the aperture 01 is a plane, while the surface S2 of the distant aperture 01 is a concave aspherical surface. At least one of the surface S2 of the second lens 20 far from the aperture 01 and the surface S1 of the first lens 10 near the aperture 01 is a plane.

[0113] The curvature radius of the curved screen 70 is R, the luminous radius of the curved screen 70 is I, and the field curvature correction value of the optical module is V. Then R, I, and V satisfy:

[0114] 0 <R-(R 2 -I 2 ) 0.5 <V<0.3mm;

[0115] Using a 1.426-inch curved screen 70 with a radius of curvature of 713.44 mm, a pixel size of 7.56 microns, the effective light-emitting area of the curved screen 70 is 23.8896 mm × 27.216 mm, the field of view angle of the optical module is 90 degrees, the eyebox of the optical module is 8 mm, 0.5 < the total system length TL of the optical module / the aperture D of the largest aperture lens < 0.9, and the effective focal length of the optical module is 16.5 mm < EFL < 20.6 mm.

[0116] The specific parameters of the optical module in Embodiment 1 are shown in Table 1:

[0117] Table 1

[0118]

[0119] The optical module of Embodiment 1, as Figures 6 to 8 shown: Figure 6 is the MTF curve of the central eyebox eyebox provided in Embodiment 1 of this application; Figure 7 is the MTF curve of the edge eyebox eyebox provided in Embodiment 1 of this application; Figure 8 is the field curvature curve of the edge eyebox eyebox provided in Embodiment 1 of this application.

[0120] As Figure 6 shown, MTF > 0.7 at 33 lp / mm, and the imaging is clear.

[0121] As Figure 7 shown, MTF > 0.7 at 33 lp / mm, and the imaging is clear.

[0122] As Figure 8 shown, the maximum value of field curvature is less than 0.1 mm. Distortion reflects the deformation condition of imaging, and the imaging deformation is small.

[0123] Embodiment 2

[0124] This Embodiment 2 uses the same optical module as Embodiment 1, and only replaces the radius of curvature of the curved screen 70 from 713 mm to 200 mm.

[0125] The specific parameters of the optical module in Embodiment 2 are shown in Table 2:

[0126] Table 2

[0127]

[0128] The optical module of Embodiment 2, as Figures 9 to 11 shown: Figure 9 is the MTF curve of the central eyebox eyebox provided in Embodiment 2 of this application; Figure 10is the MTF curve of the edge eyebox provided in Example 2 of the present application; Figure 11 It is the field curvature curve of the edge eyebox provided in Example 2 of the present application.

[0129] like Figure 9 As shown, the MTF is >0.8 at 33lp / mm, and the image is clear.

[0130] like Figure 10 As shown, the MTF is >0.7 at 33lp / mm, and the image is clear.

[0131] like Figure 11 As shown, the maximum value of field curvature is less than 0.1mm. The distortion reflects the deformation of the imaging, and the imaging deformation is small.

[0132] Example 3

[0133] The third embodiment uses the same optical module as the first embodiment, with the only difference being that the curvature radius of the curved screen 70 is changed from 713 mm to 1000 mm.

[0134] The specific parameters of the optical module of this embodiment 3 are shown in Table 3:

[0135] Table 3

[0136]

[0137] The optical module of this embodiment 3 is as follows: Figures 12 to 14 As shown: Figure 12 is the MTF curve of the central eyebox provided in Example 3 of the present application; Figure 13 is the MTF curve of the edge eyebox provided in Example 3 of the present application; Figure 14 It is the field curvature curve of the edge eyebox provided in Example 3 of the present application.

[0138] like Figure 12 As shown, the MTF is >0.7 at 33lp / mm, and the image is clear.

[0139] like Figure 13 As shown, the MTF is >0.6 at 33lp / mm, and the image is clear.

[0140] like Figure 14 As shown, the maximum value of field curvature is less than 0.1mm. The distortion reflects the deformation of the imaging, and the imaging deformation is small.

[0141] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0142] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical module, characterized in that: The optical module includes: a curved screen (70), the curved screen (70) being used to emit light, the curved direction of the curved screen (70) being oriented toward the propagation direction of the light; at least one lens, the at least one lens being located in the light-emitting direction of the curved screen (70); A beam splitter (30), a phase retarder (40), and a polarized reflective element (50), wherein the phase retarder (40) is located between the beam splitter (30) and the polarized reflective element (50), and the at least one lens is located between the beam splitter (30) and the polarized reflective element (50); The curvature radius of the curved screen (70) is R, the luminous radius of the curved screen (70) is I, and the field curvature correction value of the optical module is V. Then R, I, and V satisfy: 0<R-(R 2 -I 2 ) 0.5 <V<0.3mm。 2. The optical module according to claim 1, wherein: When the optical module includes a lens, and the eyebox is ≥ 8 mm and the field of view is ≥ 90°: The total optical length of the optical module is TL1, the aperture of the lens is D1, and the ratio of TL1 to D1 satisfies: 0.5<TL1 / D1<0.9; The effective focal length EFL1 of the optical module is: 14.5 mm < EFL1 < 18.5 mm.

3. The optical module according to claim 1, wherein: When the optical module includes two or more lenses, and the eyebox is ≥8 mm and the field of view angle is ≥90°: The total optical length of the optical module is TL2, the diameter of the largest lens in the optical module is D2, and the ratio of TL2 to D2 satisfies: 0.2<TL2 / D2<0.9; The effective focal length EFL2 of the optical module is: 11.5 mm < EFL2 < 25.5 mm.

4. The optical module according to claim 3, wherein: The lens with the largest aperture is the first lens or the second lens close to the curved screen (70).

5. The optical module according to claim 1, wherein: The at least one lens comprises a first lens (10) and a second lens (20), wherein the beam splitter (30) is arranged on a surface of the first lens (10) close to the curved screen (70), the phase retarder (40) is arranged on a surface of the first lens (10) away from the curved screen (70), and the polarized reflection element (50) is located on a surface of the second lens (20) close to the curved screen (70).

6. The optical module according to claim 1, wherein: The angle between the fast axis direction of the phase retarder (40) and the light transmission axis direction of the polarized reflection element (50) is 45 degrees; The polarization reflection element (50) is capable of reflecting one of horizontally polarized light and vertically polarized light and transmitting the other of the horizontally polarized light and vertically polarized light.

7. The optical module according to claim 1, wherein: The optical module further comprises a polarizing element (60), and the polarizing element (60) is located on a side of the polarizing reflecting element (50) away from the phase retarder (40).

8. The optical module according to claim 1, wherein: The polarizing element (60) and the polarizing reflecting element (50) are stacked together to form a stacked element, and the polarization direction of the polarizing element (60) is the same as the polarization transmission direction of the polarizing reflecting element (50).

9. The optical module according to claim 1, wherein: The optical module further comprises a screen protection sheet (80), wherein the screen protection sheet (80) is arranged on the light-emitting surface of the curved screen (70), and the curvature radius of the screen protection sheet (80) is the same as the curvature radius of the curved screen (70).

10. A head-mounted display device, characterized in that: include: case; as well as The optical module according to any one of claims 1 to 9.

Images