Optical module and intelligent head-mounted device

Abstract

The embodiment of the invention provides an optical module and intelligent head-mounted equipment. The optical module comprises a display screen, a first lens and a second lens which are arranged along the same optical axis; wherein the first lens is located between the display screen and the second lens, the first lens is a plano-concave lens, and the plane of the first lens is glued with the display screen; a light splitting element is arranged on the surface, away from the display screen, of the first lens, a phase retarder and a polarization reflection element are arranged on the surface, close to the display screen, of the second lens in a stacked mode, and the phase retarder is located between the light splitting element and the polarization reflection element.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical display technology. More specifically, the embodiments of the present application relate to an optical module and an intelligent head-mounted device. Background Art

[0002] With the rapid development of virtual reality technology, head-mounted displays (HMDs) have become an important virtual reality device, and their performance and user experience have received widespread attention. However, HMD optical modules in the prior art generally have problems such as heavy weight, long total optical length (TTL, i.e., the distance from the display screen to the exit pupil), and easy ghosting. These problems not only increase the wearing burden of users, but also may affect the imaging quality and visual experience.

[0003] Specifically, the HMD optical module in the prior art usually adopts a monolithic folded optical path design. Under the premise of maintaining a certain field of view (FOV), the TTL is often greater than 18mm, or even greater than 20mm, and the total weight of all lenses is generally more than 20g. In addition, during the assembly process of the optical module, the display screen is prone to defects due to the entry of particles. Summary of the invention

[0004] The purpose of this application is to provide a new technical solution for optical modules and smart head-mounted devices.

[0005] In a first aspect, the present application provides an optical module. The optical module comprises a display screen, a first lens and a second lens arranged along the same optical axis; wherein the first lens is located between the display screen and the second lens, the first lens is a plano-concave lens, and the plane of the first lens is glued to the display screen;

[0006] A beam splitter is disposed on the surface of the first lens away from the display screen, a phase retarder and a polarization reflection element are stacked on the surface of the second lens close to the display screen, and the phase retarder is located between the beam splitter and the polarization reflection element.

[0007] Optionally, an air gap is provided between the first lens and the second lens.

[0008] Optionally, the optical module satisfies:

[0009] 20mm<1 / 3EFL L1 <EFL All <28mm;

[0010] 20mm<1 / 3EFL L2 <EFL All <28mm;

[0011] 0.5*TTL<T<0.6*TTL;

[0012] Among them, EFL L1 is the focal length of the first lens, EFL L2 is the focal length of the second lens, EFL All is the total focal length of the optical module, and T is the straight-line distance between the second surface of the first lens and the third surface of the second lens.

[0013] Optionally, the optical module satisfies:

[0014] -50mm<R 21 <R 12 <-40mm;

[0015] -5<R 22 / R 21 <-4;

[0016] 2mm<CT L1 <CT L2 <4mm;

[0017] Among them, R 12 is the radius of curvature of the second surface of the first lens, R 21 is the radius of curvature of the third surface of the second lens, R 22 is the radius of curvature of the fourth surface of the second lens, CT L1 is the center thickness of the first lens, CT L2 is the center thickness of the second lens.

[0018] Optionally, the optical module satisfies:

[0019] 2mm<CT L1 <CT L2 <4mm;

[0020] 3<ET L1 / CT L1 <4;

[0021] 0.3<ET L2 / CT L2 <0.5;

[0022] Among them, CT L1 is the center thickness of the first lens, ET L1 is the edge thickness of the first lens, CT L2 is the center thickness of the second lens, ET L2 is the edge thickness of the second lens.

[0023] Optionally, the optical module satisfies:

[0024] 5<CA L1 / (ET L1 +CT L1 )<6;

[0025] 3<CA L2 / (ET L2 +CT L2 )<4;

[0026] Among them, CT L1 is the center thickness of the first lens, ET L1 is the edge thickness of the first lens, CA L1 is the effective aperture of the first lens, CT L2 is the center thickness of the second lens, ET L2 is the edge thickness of the second lens, CA L2 is the effective aperture of the second lens.

[0027] Optionally, the optical module further includes a polarizing element, and the polarizing element is disposed on a surface of the polarizing reflective element that is away from the phase retarder.

[0028] Optionally, the beam splitting element is a semi-transmissive and semi-reflective film, the phase retarder is a quarter-wave plate, the polarized reflective element is a polarized reflective film, and the polarizing element is a polarizing film.

[0029] Optionally, when the FOV of the optical module is not less than 90°, the total optical length is ≤17.5 mm.

[0030] In a second aspect, the present application further provides a smart head-mounted device, the smart head-mounted device comprising:

[0031] casing; and

[0032] An optical module as described in the first aspect.

[0033] The beneficial effects of this application are:

[0034] The embodiment of the present application provides an optical module, which can be applied to a head-mounted display (HMD). The optical module of the embodiment of the present application can achieve a significant reduction in the total optical length of the optical module and a reduction in the total weight of the lens by optimizing the lens design on the near-screen side and adding optical devices such as a spectrometer, a phase delay device, and a polarization reflection element at appropriate positions in the optical path, while ensuring that the imaging quality is not reduced. At the same time, it can effectively suppress the generation of "ghost images", thereby ensuring good imaging quality.

[0035] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0037] Figure 1 The structure and optical path diagram of the optical module provided in the embodiment of the present application;

[0038] Figure 2 A dot array diagram of an optical module provided in an embodiment of the present application;

[0039] Figure 3 Field curvature and distortion diagram of the optical module provided in the embodiment of the present application.

[0040] Description of reference numerals:

[0041] 1. First lens; 11. First surface; 12. Second surface; 2. Second lens; 21. Third surface; 22. Fourth surface; 3. Display screen; 4. Beam splitter; 5. Phase retarder; 6. Polarized reflective element; 7. Polarizing element; 01. Human eye. DETAILED DESCRIPTION

[0042] 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 arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0043] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0044] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0045] 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.

[0046] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0047] The optical module and the smart head-mounted device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0048] According to one embodiment of the present application, an optical module is provided. Figure 1 The optical module includes a display screen 3, a first lens 1 and a second lens 2 arranged along the same optical axis; wherein the first lens 1 is located between the display screen 3 and the second lens 2, the first lens 1 is a plano-concave lens, and the plane of the first lens 1 is glued to the display screen 3; a beam splitter 4 is arranged on the surface of the first lens 1 away from the display screen 3, a phase retarder 5 and a polarization reflection element 6 are stacked on the surface of the second lens 2 close to the display screen 3, and the phase retarder 5 is located between the beam splitter 4 and the polarization reflection element 6.

[0049] The optical module provided in the embodiment of the present application involves multiple optical elements, each of which has a specific function and works together to achieve good imaging effects and user experience. The following is an analysis of the optical elements in the optical module of the embodiment of the present application and a description of their technical effects.

[0050] The optical module provided in the embodiment of the present application includes a display screen 3, which serves as a light source part of the entire optical module and can emit light for imaging display.

[0051] The optical module provided in the embodiment of the present application includes a first lens 1, which is located on a side close to the display screen 3, and the first lens 1 is designed to be a plano-concave lens.

[0052] In the embodiment of the present application, the display screen 3 is glued together with the first lens 1 , so that the first lens 1 can be used to protect the display screen 3 .

[0053] Specifically, see Figure 1 , the first surface 11 of the first lens 1 is a plane, which is glued to the light-emitting surface of the display screen 3 to achieve a gapless connection. This tightly fitting design eliminates the gap problem that may exist in traditional designs, thereby effectively avoiding the risk of tiny particles such as dust and impurities falling on the display screen 3. In a smart head-mounted device, any tiny contamination may have a serious impact on the imaging quality, so this design enhances the reliability and durability of the smart head-mounted device.

[0054] It should be noted that in the optical module provided in the application embodiment, the display screen 3 is a core component, and its light-emitting surface is relatively fragile. Once it is dirty, directly wiping or touching it is very likely to cause irreversible damage, thereby affecting the display effect of the entire optical module. Given that the manufacturing precision and cost of the display screen 3 are both high, any form of physical damage will result in expensive repair or replacement costs, which undoubtedly increases the maintenance cost and use risk of the product.

[0055] Therefore, the protection of the display screen 3 is considered as one of the factors in the initial design of the optical solution of the present application. By designing the first surface 11 of the first lens 1 to be a plane and directly gluing it to the light-emitting surface of the display screen 3, the display screen 3 is effectively isolated from direct contact with the external environment, thereby greatly reducing the risk of damage to the display screen 3.

[0056] The first lens 1 provided in the present application is a plano-concave lens. The design of the plano-concave lens can also effectively control the divergence of light, so that the light is more concentrated before entering the second lens 2, reducing the generation of stray light, which helps to reduce the "ghost" phenomenon.

[0057] The optical module provided in the embodiment of the present application includes a second lens 2, see Figure 1 The second lens 2 is located on the side of the first lens 1 away from the display screen 3. The second lens 2 can further focus the light passing through the first lens 1 to form a clear image.

[0058] In addition to the above-mentioned display screen 3, first lens 1 and second lens 2, the optical module provided in the embodiment of the present application also includes optical elements such as a beam splitter 4, a phase retarder 5 and a polarization reflection element 6, and the beam splitter 4, the phase retarder 5 and the polarization reflection element 6 are designed to be located between the first lens 1 and the second lens 2 to achieve optical path folding.

[0059] The light splitting element 4 is located on the surface close to the first lens 1, that is, the second surface 12, and is used to split the light from the first lens 1 into two parts, one part is directly transmitted, and the other part is reflected. Through the light splitting effect, the distribution of light and the change of the path are achieved, providing conditions for subsequent phase delay and polarization reflection.

[0060] The phase retarder 5 and the polarized reflection element 6 are arranged together on the surface of the second lens 2 close to the display screen 3, i.e., the third surface 21. Specifically, the phase retarder 5 is located after the beam splitter 4, and changes the polarization state of the light through the phase delay effect. The polarized reflection element 6 is located after the phase retarder 5, and is used to perform polarized reflection on the light adjusted by the phase retarder 5. Through the polarized reflection effect, the light is re-reflected and focused, which improves the utilization rate of the light and the imaging quality. At the same time, the selective reflection characteristics of the polarized reflection element 6 help to reduce unnecessary reflections and interference, and further reduce the generation of "ghost images".

[0061] In one example, the beam splitter 4 is a semi-transparent and semi-reflective film, which can transmit a portion of the light and reflect a portion of the light. The phase retarder 5 is a quarter-wave plate, which is used to adjust the phase of the light. The polarized reflective element 6 is a polarized reflective film, which is located after the phase retarder 5 and can reflect or transmit according to the polarization state of the light.

[0062] In the optical module provided in the embodiment of the present application, the combination of the beam splitter 4, the phase retarder 5 and the polarized reflective element 6 together constitutes an efficient folded optical path. This design can not only shorten the optical length (TTL) of the optical module, but also realize multiple folding and modulation of light, which is conducive to improving imaging quality.

[0063] It should be noted that the optical module provided in the present application adopts a design of folding the light path between air layers, which reduces the messy reflection of light between lenses and also helps to reduce the generation of "ghost images".

[0064] The embodiment of the present application provides an optical module, which can be applied to a head-mounted display (HMD). The optical module of the embodiment of the present application can achieve a significant reduction in the total optical length of the optical module and a reduction in the total weight of the lens by optimizing the lens design on the near-screen side and adding optical devices such as a spectrometer 4, a phase retarder 5 and a polarization reflection element 6 at appropriate positions in the optical path, while ensuring that the imaging quality is not reduced. At the same time, it can effectively suppress the generation of "ghost images", thereby ensuring good imaging quality.

[0065] It is also important to emphasize that, since the display screen 3 and the first lens 1 are bonded together, the risk of defects caused by particles falling into the display screen during assembly is reduced. This optimization not only improves the overall reliability of the optical assembly, but also significantly enhances the stability and durability of the final product, bringing users a more reliable and stable use experience.

[0066] The optical module provided in the embodiments of the present application can provide a good user experience for applications such as virtual reality.

[0067] In some examples of the present application, an air gap is provided between the first lens 1 and the second lens 2 .

[0068] In this example of the present application, an air gap is provided between the first lens 1 and the second lens 2, and the beam splitter 4, the phase retarder 5 and the polarized reflective element 6 are located in the air gap, so that the light does not pass through the lens when being folded in the air gap. This design can bring the following technical effects:

[0069] Ability to reduce reflection and interference inside the lens: When light passes through a lens, it will reflect and interfere inside the lens, which may cause phenomena such as "ghost images". By placing the beam splitter 4, the phase retarder 5 and the polarized reflective element 6 in the air gap, the light will be reflected at the interface between the air and the lens instead of inside the lens. This helps to reduce reflection and interference inside the lens, thereby reducing the occurrence of phenomena such as "ghost images".

[0070] In addition, the air gap can also serve as a propagation medium for light. Its refractive index is different from that of the lens material, which helps to further adjust the propagation path and focusing effect of light, thereby optimizing the imaging quality.

[0071] In some examples of this application, see Figure 1 The first lens 1 includes a first surface 11 and a second surface 12 ; the first surface 11 is a plane and is glued to the display screen 3 ; the second surface 12 is a concave surface, and the light splitting element 4 is arranged on the second surface 12 .

[0072] The first lens 1 provided in the present application includes two surfaces, namely a first surface 11 and a second surface 12. The first surface 11 is designed to be a plane so that it can be tightly glued to the display screen 3. The first surface 11 of the first lens 1 is glued to the display screen 3. This connection method reduces the loss of light in the air gap between the first lens 1 and the display screen 3 and improves the utilization rate of light. At the same time, this glue connection also enhances the stability between the first lens 1 and the display screen 3, which helps to maintain the overall performance of the optical module.

[0073] The concave design of the second surface 12 is helpful for the convergence and divergence of light, further enhancing the imaging capability of the optical system. In addition, the second surface 12 also provides a suitable substrate for the arrangement of the light splitting element 4.

[0074] In the optical module provided in the embodiment of the present application, the beam splitter element 4 is disposed on the second surface 12 of the first lens 1. The beam splitter element 4 is, for example, a semi-transparent and semi-reflective film.

[0075] Specifically, a semi-transparent and semi-reflective film can be coated on the second surface 12 of the first lens 1, so that the light can be split according to a specific ratio when passing through the second surface 12, which helps to achieve a reasonable distribution of light in the optical module, thereby optimizing the overall optical path structure.

[0076] In addition, by directly arranging the light splitting element 4 on the surface of the first lens 1 , additional optical elements and assembly steps are reduced, thereby reducing the manufacturing and assembly costs.

[0077] In the present application, the entire optical module is made more compact and integrated by tightly gluing the first lens 1 to the display screen 3 and arranging the light splitting element 4 on the surface of the first lens 1. This compact layout helps to reduce the volume of the optical module and improve its application flexibility in virtual reality (VR) or augmented reality (AR) devices.

[0078] In some examples of this application, see Figure 1 The second lens 2 includes a third surface 21 and a fourth surface 22, the third surface 21 and the second surface 12 are adjacent and spaced apart; the phase retarder 5 and the polarizing reflection element 6 are stacked and disposed on the third surface 21.

[0079] The second lens 2 provided in the present application includes two surfaces: a third surface 21 and a fourth surface 22, wherein the third surface 21 is adjacent to and spaced from the second surface 12 of the first lens 1. This air gap provides necessary space for light transmission between lenses and allows optical elements to be arranged on the third surface 21.

[0080] In the optical module provided in the embodiment of the present application, the phase retarder 5 and the polarized reflective element 6 are directly stacked and arranged on the third surface 21 of the second lens 2. Among them, the main function of the phase retarder 5 is to adjust the phase of the light, so as to achieve precise control of the polarization state of the light. The polarized reflective element 6 can reflect or transmit according to the polarization direction of the light, and further manipulate the transmission path of the light. The stacking of the phase retarder 5 and the polarized reflective element 6 on the third surface 21 enables them to act together on the passing light to achieve fine control of the polarization state and transmission path of the light. This synergistic effect helps to optimize the performance of the optical module and improve the imaging quality. This optical regulation helps to reduce stray light and "ghost" phenomena and improve image clarity.

[0081] In addition, by stacking the phase retarder 5 and the polarized reflective element 6 on the third surface 21 of the second lens 2, a compact layout of optical elements can be achieved. This layout helps to reduce the volume of the optical module and improve its integration and application flexibility.

[0082] Optionally, an anti-reflection film may be coated on the fourth surface 22 of the second lens 2 .

[0083] The main function of anti-reflective film is to increase the amount of light that passes through the lens by reducing the reflection of light on the lens surface. In devices such as virtual reality (VR), increasing light transmittance helps improve image brightness and clarity.

[0084] It should be noted that reducing reflected light can reduce direct stimulation of light to the eyes, especially in strong light environments, reduce eye fatigue and improve the comfort of wearing VR equipment for a long time.

[0085] In addition, the anti-reflective film can maintain the color balance of light, reduce color distortion caused by reflection, and make the transmitted light closer to the color of the original light source, thereby improving the color reproduction of the image.

[0086] In some examples of the present application, the optical module satisfies the following relationship:

[0087] 20mm<1 / 3EFL L1 <EFL All <28mm;

[0088] 20mm<1 / 3EFL L2 <EFL All <28mm;

[0089] 0.5*TTL<T<0.6*TTL;

[0090] Among them, EFL L1 is the focal length of the first lens 1, EFL L2 is the focal length of the second lens 2, EFL All is the total focal length of the optical module, and T is the straight-line distance between the second surface 12 of the first lens 1 and the third surface 21 of the second lens 2 .

[0091] According to this example of the present application, the focal length design of the first lens 1 is described, specifically: 20mm<1 / 3EFL L1 <EFL All <28mm. This inequality indicates that the focal length of the first lens 1 (EFL L1 ) is greater than 20 mm, and the total focal length of the entire optical module (EFL All ) is between one third of the focal length of the first lens 1 and 28 mm. This ensures that the first lens 1 has a sufficient focal length to provide the required imaging characteristics.

[0092] In this example of the present application, the focal length design of the second lens 2 is also described, specifically: 20mm<1 / 3EFL L2 <EFL All <28mm. For the second lens 2, its focal length (EFL L2 ) is also greater than 20 mm, and the total focal length of the entire optical module is also between one-third of the focal length of the second lens 2 and 28 mm. This means that the focal lengths of the two lenses are carefully designed to ensure the balance of the overall performance of the entire optical module.

[0093] This example of the present application also describes the design of the air gap between the first lens 1 and the second lens 2, that is, 0.5*TTL<T<0.6*TTL. This formula specifies the straight-line distance T (i.e., air gap) between the second surface 12 of the first lens 1 and the third surface 21 of the second lens 2, which is between half and sixty percent of the total optical length (TTL) of the entire optical module. Such a design helps to control the refraction and scattering of light when it passes through the lens, thereby improving the utilization rate of light and image quality.

[0094] According to this example of the present application, by precisely controlling the focal length of each lens and the air space (ie, T) between two lenses, the total optical length TTL of the entire optical module can be controlled to be less than 17.5 mm, thereby reducing the volume of the entire optical module.

[0095] At the same time, the entire optical module can transmit and focus light more efficiently, reducing light refraction and scattering losses. Fine control of focal length and air spacing also helps reduce aberration and distortion, improving image clarity. This enables the optical module to provide more realistic and natural imaging effects.

[0096] In some examples of the present application, the optical module satisfies the following relationship:

[0097] -50mm<R 21 <R 12 <-40mm;

[0098] -5<R 22 / R 21 <-4;

[0099] 2mm<CT L1 <CT L2 <4mm;

[0100] Among them, R 12 is the radius of curvature of the second surface 12 of the first lens 1, R 21 is the radius of curvature of the third surface 21 of the second lens 2, R 22 is the radius of curvature of the fourth surface 22 of the second lens 2, CT L1 is the center thickness of the first lens 1, CT L2 is the center thickness of the second lens 2.

[0101] In this example of the present application, it is described that -50 mm < R 21 <R 12 <-40mm, this formula indicates that the curvature radius R of the third surface 21 of the second lens 2 21The absolute value of the curvature radius R of the second surface 12 of the first lens 1 is smaller than 12 The absolute value of the two lenses is between -50mm and -40mm. This design helps control the refraction angle of light when it passes through the lens, allowing the light to be more tightly focused on the image plane.

[0102] It is also described in this example of the present application that -5<R 22 / R 21 <-4, this formula stipulates the curvature radius R of the fourth surface 22 of the second lens 2 22 The curvature radius R of the third surface 21 is 21 This ratio range ensures that there is an appropriate curvature difference between the two surfaces of the second lens 2, thereby helping to further control the refraction and focusing characteristics of light.

[0103] It is also described in this example of the present application that 2 mm < CT L1 <CT L2 <4mm, this formula means that the center thickness of the two lenses is controlled within 2mm~4mm. The center thickness of the lens is also an important design parameter. A thinner center thickness of the lens helps to reduce the propagation path length of the light inside the lens, thereby reducing the EFL. However, the thickness of the lens also needs to be balanced between ensuring sufficient mechanical strength and optical performance.

[0104] In the present application, by carefully designing the lens surface curvature radius and center thickness, the entire optical module can achieve a smaller EFL. A smaller EFL means that light can be more closely focused on the image plane, thereby improving the clarity and resolution of the image.

[0105] Furthermore, in the present application, precise control of the lens surface curvature radius and center thickness also helps to reduce aberration and distortion and improve image quality, which enables the optical module to provide more accurate and natural imaging effects.

[0106] In some examples of the present application, the optical module satisfies the following relationship:

[0107] 2mm<CT L1 <CT L2 <4mm;

[0108] 3<ET L1 / CT L1 <4;

[0109] 0.3<ET L2 / CT L2 <0.5;

[0110] Among them, CT L1is the center thickness of the first lens 1, ET L1 is the edge thickness of the first lens 1, CT L2 is the center thickness of the second lens 2, ET L2 is the edge thickness of the second lens 2.

[0111] CT L1 With CT L2 Relationship: CT L1 Represents the center thickness of the first lens 1, CT L2 represents the center thickness of the second lens 2. The above relationship 2mm<CT L1 <CT L2 <4mm indicates that the center thickness of the two lenses is controlled between 2mm and 4mm, and the center thickness of the second lens 2 is slightly larger than that of the first lens 1. This design not only ensures the structural strength of each lens, but also achieves lightweight.

[0112] ET L1 With E.T. L2 Relationship: E.T. L1 Represents the edge thickness of the first lens 1. Relation 3<ET L1 / CT L1 <4 indicates that the ratio of the edge thickness to the center thickness of the first lens 1 is between 3 and 4. This means that the edge thickness is larger than the center thickness, which helps to enhance the anti-deformation ability of the lens while keeping the overall weight under control.

[0113] ET L2 With CT L2 Relationship: ET L2 Represents the edge thickness of the second lens 2. Relational formula 0.3<ET L2 / CT L2 <0.5 indicates that the ratio of the edge thickness to the center thickness of the second lens 2 is between 0.3 and 0.5. Compared with the first lens 1, the edge thickness ratio of the second lens 2 is lower, which helps to further reduce the weight while maintaining sufficient structural strength.

[0114] In some examples of the present application, the optical module also satisfies the following relationship:

[0115] 5<CA L1 / (ET L1 +CT L1 )<6;

[0116] 3<CA L2 / (ET L2 +CT L2 )<4;

[0117] Among them, CT L1is the center thickness of the first lens 1, ET L1 is the edge thickness of the first lens 1, CA L1 is the effective aperture of the first lens 1, CT L2 is the center thickness of the second lens 2, ET L2 is the edge thickness of the second lens 2, CA L2 is the effective aperture of the second lens 2.

[0118] CT L1 Represents the effective aperture of the first lens 1. Relational Formula 5<CA L1 / (ET L1 +CT L1 )<6 indicates that the ratio between the effective aperture of the first lens 1 and its total thickness (edge ​​thickness + center thickness) is between 5 and 6. A larger ratio helps to improve the optical performance of the lens, such as a larger field of view and better imaging quality, while maintaining lightweight.

[0119] CT L2 Represents the effective aperture of the second lens. Relation 3<CA L2 / (ET L2 +CT L2 )<4 indicates that the ratio between the effective aperture of the second lens 2 and its total thickness is between 3 and 4. By controlling the ratio, the optical performance and structural strength of the lens can be optimized while keeping the lens lightweight.

[0120] The above two examples achieve lightweighting, structural strengthening and improved imaging quality of the optical module by precisely controlling the proportional relationship between the center thickness, edge thickness and effective aperture of the lens.

[0121] Furthermore, when the optical module satisfies the following relationships at the same time, the weight of the optical module is further optimized to better achieve lightweighting of the optical module. The specific relationships are as follows:

[0122] 2mm<CT L1 <CT L2 <4mm;

[0123] 3<ET L1 / CT L1 <4;

[0124] 0.3<ET L2 / CT L2 <0.5;

[0125] 5<CA L1 / (ET L1 +CT L1 )<6;

[0126] 3<CA L2 / (ET L2 +CT L2 )<4;

[0127] Among them, CT L1 is the center thickness of the first lens 1, ET L1 is the edge thickness of the first lens 1, CA L1 is the effective aperture of the first lens 1, CT L2 is the center thickness of the second lens 2, ET L2 is the edge thickness of the second lens 2, CA L2 is the effective aperture of the second lens 2.

[0128] In this example of the present application, the center thickness of the two lenses is described, that is, 2mm < CT L1 <CT L2 <4mm. This condition limits the center thickness range of each lens, ensuring that the lens is neither too thick to increase weight nor too thin to affect manufacturing and optical performance.

[0129] Specifically, by controlling the thickness of the first lens 1 to be between 2 mm and 4 mm, and designing the center thickness of the second lens 2 to be slightly larger than the center thickness of the first lens 1 , lightweight can be achieved while maintaining structural strength.

[0130] In this example of the present application, 3<ET is described. L1 / CT L1 <4; among them, ET L1 is the edge thickness of the first lens 1, CT L1 is the center thickness of the first lens 1. This ratio condition ensures the rationality of the edge thickness of the first lens 1 relative to the center thickness, which helps to balance the rigidity and lightness requirements of the lens. A larger edge thickness ratio design can improve the lens's anti-deformation ability while keeping the overall weight under control.

[0131] In this example of the present application, 0.3 < ET is described. L2 / CT L2 <0.5; where ET L2 is the edge thickness of the second lens 2, CT L2 is the center thickness of the second lens 2. Similar to the first lens 1, this condition limits the ratio of the edge thickness to the center thickness of the second lens 2 to achieve more reasonable weight distribution and mechanical performance. A lower ratio helps to further reduce the weight of the second lens while maintaining sufficient structural strength.

[0132] In this example of the present application, 5 < CA is described.L1 / (ET L1 +CT L1 )<6; among them, CA L1 is the effective aperture of the first lens 1, and this condition ensures a reasonable ratio between the effective aperture of the first lens 1 and its total thickness (edge ​​thickness + center thickness). A larger ratio helps to improve the optical performance of the lens, such as a larger field of view and better imaging quality, while maintaining lightweight.

[0133] In this example of the present application, 3 < CA is described. L2 / (ET L2 +CT L2 )<4; among them, CA L2 is the effective aperture of the second lens. Similar to the first lens 1, this condition limits the ratio between the effective aperture of the second lens 2 and its total thickness. By controlling the ratio, the optical performance and structural strength of the lens can be optimized while keeping it lightweight.

[0134] According to this example of the present application, by controlling the ratio of the center thickness, edge thickness and effective aperture of each lens, the entire optical module can be made lightweight, which is crucial to improving the wearing comfort of the HMD device.

[0135] In addition, reasonable lens thickness and ratio design can help reduce aberrations and ghosting, improve imaging quality and field of view. In addition, appropriate edge thickness and ratio design can enhance the lens's anti-deformation ability and improve the stability and durability of the optical module.

[0136] In some examples of this application, see Figure 1 The optical module further includes a polarizing element 7 , and the polarizing element 7 is disposed on a surface of the polarizing reflecting element 6 that is away from the phase retarder 5 .

[0137] The optical module provided in the embodiment of the present application may further include a polarizing element 7 . The polarizing element 7 , the polarizing reflecting element 6 and the phase retarder 5 may be stacked in sequence to form a composite film, and the composite film may be directly attached to the third surface 21 of the second lens 2 .

[0138] The composite film formed by the phase retarder 5, the polarized reflective element 6 and the polarizing element 7 can accurately control the polarization direction and reflection path of the light, and reduce the loss and interference of the light. This design helps to eliminate or reduce image distortion and "ghosting" caused by mismatched polarization states, thereby improving the clarity of imaging.

[0139] Optionally, an anti-reflection film may be added to the composite film, and the anti-reflection film is arranged on a side of the phase retarder 5 away from the polarized reflection element 6 .

[0140] The entire composite film has multiple functions, including polarization correction, phase delay and anti-reflection, which can further reduce the reflection and interference of light and improve the imaging quality.

[0141] In some examples of the present application, the beam splitter element 4 is a semi-transmissive and semi-reflective film, the phase retarder 5 is a quarter-wave plate, the polarized reflective element 6 is a polarized reflective film, and the polarizing element 7 is a polarizing film.

[0142] In some examples of the present application, the total optical length of the optical module is ≤17.5 mm when the FOV of the optical module is not less than 90°.

[0143] The optical module provided in the embodiment of the present application is shown in FIG. Figure 1 A plano-concave lens (ie, the first lens 1) is added on the side close to the display screen 3, and a plurality of optical films and air layers are used to realize light path folding.

[0144] Please continue to see Figure 1 , the light emitted by the display screen 3 enters the interior of the first lens 1 through the first surface 11 of the first lens 1, and about 50% of the light is emitted into the air gap (located between the first lens 1 and the second lens 2) after passing through the second surface 12; after passing through the optical film (including the phase retarder 5 and the polarization reflection element 6, etc.) attached to the third surface 21 of the second lens 2, it is reflected back to the air layer to the second surface 12, and after being reflected again, 50% of the light is reflected back to the air gap. Due to the change in polarization direction, the light can enter the interior of the second lens 2 after passing through the third surface 21 again, and then enter the human eye 01 through the fourth surface 22 of the second lens 2. Among them, the light path folding between the air layers is realized, avoiding the influence of internal stress birefringence.

[0145] The optical module of the present application, by precisely designing the optical parameters such as the curvature, thickness and material of the first lens 1 and the second lens 2, reduces the total optical length TTL of the entire optical module to 15.4 mm when the FOV is not less than 90°, and the total weight of the two lenses is reduced to less than 9g.

[0146] The optical module provided in the embodiment of the present application has high imaging quality. The spot size in the whole field of view is controlled within about 66 microns, which ensures the clarity of the image and brings a more realistic visual experience to the user.

[0147] The present application is described in detail below through Example 1.

[0148] Example 1

[0149] See also Figure 1 , the optical module comprises a display screen 3, a first lens 1 and a second lens 2 which are sequentially arranged along the same optical axis;

[0150] The first lens 1 is a plano-concave lens, and includes a first surface 11 and a second surface 12. The first surface 11 is a plane and is glued to the display screen 3, and the second surface 12 is a concave surface, and a light splitting element 4 (such as a semi-transparent and semi-reflective film) is plated on the second surface 12.

[0151] The second lens 2 includes a third surface 21 and a fourth surface 22, the third surface 21 is close to the second surface 12, a composite film is attached to the third surface 21, and the composite film includes a phase retarder 5, a polarization reflection element 6 and a polarization element 7 stacked in sequence; the phase retarder 5 is a quarter wave plate, the polarization reflection element 6 is a polarization reflection film, the polarization element 7 is a polarization film, and the phase retarder 5 is located between the beam splitting element 4 and the polarization reflection element 6;

[0152] The display screen 3 is, for example, 2.1 inches.

[0153] The optical parameters of the optical module are specifically shown in Table 1 below.

[0154] Table 1

[0155]

[0156]

[0157] The optical module provided in this specific example has optical properties such as Figure 2 and Figure 3 As shown: Figure 2 is a schematic diagram of the point diagram. Figure 3 This is the field curvature distortion diagram.

[0158] The spot diagram refers to a diffuse diagram formed by many light rays emitted from one point after passing through the optical system. Due to aberration, their intersection points with the image plane are no longer concentrated at the same point, but are scattered in a certain range. It is used to evaluate the imaging quality of the projection optical system. Figure 2 In the optical module provided in this specific example, the maximum value of the image point in the point diagram is less than 65 μm, which means that the optical module can maintain good imaging clarity at different viewing angles (for smart head-mounted devices, the clarity is sufficient to meet user needs).

[0159] See also Figure 3The optical module provided in this specific example has a field curvature of less than 1.3mm under the full field of view (such as 90°, the half field of view θ is 45°), and the absolute value of distortion is less than 22.6%, which means that the distortion generated during the imaging process of the optical module is very small and can fully meet the user's imaging requirements for smart head-mounted devices.

[0160] In general, the optical module provided in the embodiments of the present application can meet the requirements of HMD applications for light weight, low ghosting, and high imaging quality.

[0161] According to another embodiment of the present application, a smart head-mounted device is provided, wherein the smart head-mounted device includes a housing and the optical module as described above.

[0162] The smart head-mounted device provided in the embodiment of the present application is, for example, a VR smart head-mounted device, such as VR smart glasses or a VR smart helmet.

[0163] The specific implementation of the intelligent head mounted device of the embodiment of the present application can refer to the above-mentioned embodiments of the optical module, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0164] 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.

[0165] 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 only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments 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 invention comprises a display screen (3), a first lens (1) and a second lens (2) arranged along the same optical axis; wherein the first lens (1) is located between the display screen (3) and the second lens (2); the first lens (1) is a plano-concave lens; and the plane of the first lens (1) is glued to the display screen (3); A beam splitter (4) is arranged on the surface of the first lens (1) away from the display screen (3), and a phase retarder (5) and a polarization reflection element (6) are stacked on the surface of the second lens (2) close to the display screen (3), and the phase retarder (5) is located between the beam splitter (4) and the polarization reflection element (6).

2. The optical module according to claim 1, characterized in that: An air gap is provided between the first lens (1) and the second lens (2).

3. The optical module according to claim 2, characterized in that: The optical module meets the following requirements: 20mm<1 / 3EFL L1 <EFL All <28mm; 20mm<1 / 3EFL L2 <EFL All <28mm; 0.5*TTL<T<0.6*TTL; Among them, EFL L1 is the focal length of the first lens (1), EFL L2 is the focal length of the second lens (2), EFL All is the total focal length of the optical module, and T is the straight-line distance between the second surface (12) of the first lens (1) and the third surface (21) of the second lens (2).

4. The optical module according to claim 3, characterized in that: The optical module meets the following requirements: -50mm<R 21 <R 12 <-40mm; -5<R 22 / R 21 <-4; 2mm<CT L1 <CT L2 <4mm; Among them, R 12 is the radius of curvature of the second surface (12) of the first lens (1), R 21 is the radius of curvature of the third surface (21) of the second lens (2), R 22 is the radius of curvature of the fourth surface (22) of the second lens (2), CT L1 is the center thickness of the first lens (1), CT L2 is the central thickness of the second lens (2).

5. The optical module according to claim 3, characterized in that: The optical module meets the following requirements: 2mm<CT L1 <CT L2 <4mm; 3<ET L1 / CT L1 <4; 0.3<ET L2 / CT L2 <0.5; Among them, CT L1 is the central thickness of the first lens (1), ET L1 is the edge thickness of the first lens (1), CT L2 is the central thickness of the second lens (2), ET L2 is the edge thickness of the second lens (2).

6. The optical module according to claim 5, characterized in that: The optical module also satisfies: 5<CA L1 / (AND L1 +CT L1 )<6; 3<CA L2 / (AND L2 +CT L2 )<4; Among them, CT L1 is the central thickness of the first lens (1), ET L1 is the edge thickness of the first lens (1), CA L1 is the effective aperture of the first lens (1), CT L2 is the central thickness of the second lens (2), ET L2 is the edge thickness of the second lens (2), CA L2 is the effective aperture of the second lens (2).

7. The optical module according to claim 1, characterized in that: The optical module further comprises a polarizing element (7), wherein the polarizing element (7) is arranged on a surface of a side of the polarizing reflecting element (6) that is away from the phase retarder (5).

8. The optical module according to claim 7, characterized in that: The beam splitter element (4) is a semi-transmissive and semi-reflective film, the phase retarder (5) is a quarter-wave plate, the polarized reflective element (6) is a polarized reflective film, and the polarizing element (7) is a polarizing film.

9. The optical module according to any one of claims 1 to 8, characterized in that: When the FOV of the optical module is not less than 90°, the total optical length is ≤17.5 mm.

10. A smart head mounted device, characterized in that: include: shell; and An optical module as claimed in any one of claims 1 to 9.

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