Optical system and head-mounted display device

Abstract

The embodiment of the invention provides an optical system and head-mounted display equipment. The optical system comprises a display assembly, a lens assembly and a prism assembly. The display assembly comprises a first screen and a second screen which are respectively used for providing central field-of-view light and edge field-of-view light. The lens assembly is located on the light emitting side of the second screen and comprises a lens, a light splitting element is arranged on one surface of the lens, a first phase delay piece and a composite film are arranged at different calibers of the other surface of the lens respectively, and the composite film at least comprises a polarization light splitting film and a second phase delay piece; the prism assembly and the first screen are located on the side, away from the second screen, of the lens assembly together, the prism assembly comprises a first prism, a second prism and a reflective polarizing film located between the first prism and the second prism, and the first screen and the second prism are arranged adjacently. The first screen is located on the side, away from the reflective polarizing film, of the second prism.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and more specifically, to an optical system and a head-mounted display device. Background Technology

[0002] With the development of virtual reality (VR) technology, consumers have placed higher demands on the thinness, image quality, and wearing comfort of VR products. Traditional virtual reality optical systems typically employ a single-screen, single-optical-system architecture, resulting in a relatively small average PPD (pixels per degree) across the entire field of view, especially in the central field of view, where the human eye has high requirements for PPD, a demand that current technology struggles to meet. Furthermore, existing optical systems with varying PPDs tend to be thicker, increasing the overall size of the device and negatively impacting the user's wearing experience. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for an optical system and a head-mounted display device.

[0004] In a first aspect, embodiments of this application provide an optical system, the optical system comprising:

[0005] The display component includes a first screen and a second screen, wherein the first screen is used to provide a central field of view ray and the second screen is used to provide an edge field of view ray.

[0006] A lens assembly is located on the light-emitting side of the second screen. The lens assembly includes at least one lens. A beam-splitting element is disposed on one surface of the lens, and a first phase retardation film and a composite film are respectively disposed at different apertures on the other surface. The composite film includes at least a polarizing beam-splitting film and a second phase retardation film.

[0007] A prism assembly, together with the first screen, is located on the side of the lens assembly opposite to the second screen. The prism assembly includes a first prism, a second prism, and a reflective polarizing film located between the two. The first screen is disposed adjacent to the second prism, and the first screen is located on the side of the second prism opposite to the reflective polarizing film.

[0008] Optionally, the beam-splitting element is disposed on the surface of the lens near the second screen;

[0009] The first phase retardation film and the composite film are disposed on the surface of the lens away from the second screen, wherein the first phase retardation film is located in the middle and the composite film surrounds the periphery of the first phase retardation film.

[0010] Optionally, the central field-of-view light rays are emitted from the first screen, pass through the second prism, are reflected by the reflective polarizing film to the central region of the lens and propagate back, and then pass through the second prism and the first prism again to form a central field-of-view image after exiting;

[0011] The edge field of view light is emitted from the second screen, projected onto the edge region of the lens and propagated back, then passes through the prism assembly, and after exiting, forms an edge field of view image that is continuously connected to the central field of view image.

[0012] Optionally, the lens is a plano-convex lens;

[0013] The surface of the lens near the second screen is convex and aspherical, and the beam splitting element is disposed on the convex surface of the lens;

[0014] The first phase delay film and the composite film are disposed on the plane of the lens.

[0015] Optionally, the first prism and the second prism are bonded together, and the reflective polarizing film is located on the bonded surface of the first prism and the second prism.

[0016] Optionally, the first prism and the second prism are glued together to form a flat plate element;

[0017] Wherein, the cemented surfaces of the first prism and the second prism form a set angle θ with respect to the optical axis of the lens, and the set angle θ is 20°≤θ≤30°.

[0018] Optionally, the first prism and the second prism are made of resin material.

[0019] Optionally, an air gap is provided between the prism assembly and the lens assembly.

[0020] Optionally, the central field of view light emitted from the first screen is projected into the second prism and can undergo total internal reflection in the second prism before being projected onto the reflective polarizing film.

[0021] Optionally, the composite film further includes a polarizing film, which is stacked sequentially with the polarizing beam splitter and the second phase retarder.

[0022] Optionally, the beam splitter is a semi-transparent and semi-reflective film, and the first phase retarder and the second phase retarder are quarter-wavelength phase films.

[0023] Optionally, the size of the first screen is smaller than the size of the second screen;

[0024] The size of the first screen is less than 0.9 inches.

[0025] Optionally, the first screen is a Micro-OLED screen, and the second screen is a Micro-OLED or LCD screen.

[0026] Secondly, embodiments of this application provide a head-mounted display device, the head-mounted display device comprising:

[0027] The outer casing; and

[0028] The optical system as described in the first aspect is disposed on the housing.

[0029] One beneficial effect of this application is:

[0030] The optical system provided in this application is a novel virtual reality optical system with different angular resolutions. By setting up a first screen and a second screen, as well as lens and prism components shared by the two screens, and cooperating with a folded optical path, it achieves a small FOV and high angular resolution in the central field of view area, and a large FOV and lower angular resolution in the edge field of view area, significantly improving image quality. At the same time, the optical design of this application effectively reduces the thickness of the entire optical system, making the whole device lighter and thinner, thereby improving the user's wearing comfort. In addition, since the central field of view and the edge field of view share the optical path and optical components, the optical structure of the entire optical system is simplified, reducing manufacturing costs.

[0031] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0033] Figure 1 The structure and optical path diagram of the optical system provided in the embodiments of this application;

[0034] Figure 2 Imaging optical path diagram of the central field of view of the optical system provided in the embodiments of this application;

[0035] Figure 3 A schematic diagram of the edge field of view of the optical system provided in the embodiments of this application;

[0036] Figure 4 This is a schematic diagram of the lens coating provided in an embodiment of this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. First screen; 2. Second screen; 3. Lens assembly; 4. Prism assembly;

[0039] 31. Lens; 32. Beam splitter; 33. Phase retardation film; 34. Composite film;

[0040] 41. First prism; 42. Second prism; 43. Reflective polarizing film;

[0041] 01. The human eye. Detailed Implementation

[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, numerical expressions, and values ​​of the components and steps 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 and is in no way intended to limit the scope of this application and its application or use.

[0044] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0045] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

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

[0047] The optical system and head-mounted display device provided in the embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0048] According to one embodiment of this application, an optical system is provided that can be applied to, for example, virtual reality display devices (VR devices) or mixed reality display devices (MR devices).

[0049] The optical system provided in this application embodiment is described in [reference]. Figure 1The optical system includes a display component, a lens component 3, and a prism component 4. The display component includes a first screen 1 and a second screen 2. The first screen 1 provides central field of view light, and the second screen 2 provides peripheral field of view light. The lens component 3 is located on the light-emitting side of the second screen 2. The lens component 3 includes at least one lens 31. One surface of the lens 31 is provided with a beam-splitting element 32, and different apertures on the other surface are respectively provided with a first phase retardation film 33 and a composite film 34. The composite film 34 includes at least a polarizing beam-splitting film and a second phase retardation film. The prism component 4, together with the first screen 1, is located on the side of the lens component 3 facing away from the second screen 2. The prism component 4 includes a first prism 41, a second prism 42, and a reflective polarizing film 43 located between them. The first screen 1 and the second prism 42 are arranged adjacent to each other, and the first screen 1 is located on the side of the second prism 42 facing away from the reflective polarizing film 43.

[0050] The optical system provided in this application embodiment is described in [reference]. Figure 1 The optical architecture shown mainly consists of three optical components: a display component, a lens component 3, and a prism component 4; wherein, the display component includes two screens, respectively Figure 1 The first screen 1 and the second screen 2 shown are used to provide central field of view light and edge field of view light respectively, and the two screens share the lens assembly 3 and the prism assembly 4.

[0051] In the optical system provided in this application embodiment, the display component, as the source of image information, is designed to mainly consist of two screens—a first screen 1 and a second screen 2. The first screen 1 provides the central field of view light, and the light emitted from it constitutes the central region of the user's field of vision, which requires high resolution. Therefore, the first screen 1 is, for example, a high-resolution display, such as a Micro-OLED.

[0052] The second screen 2 is responsible for providing edge field of view light. The light it emits forms the outer area of ​​the user's field of view. This area has relatively lower resolution requirements but a larger field of view. Therefore, the second screen 2 may be a large-size Micro-OLED or LCD screen.

[0053] In the optical system provided in this application embodiment, the lens assembly 3 is located on the light-emitting side of the second screen 2, and the lens assembly 3 and the second screen 2 are spaced apart along the same optical axis.

[0054] Specifically, the lens assembly 3 may include at least one lens 31, and a beam splitter 32 is disposed on one surface of the lens 31 for transmitting and reflecting light. A first phase retarder 33 and a composite film 34 are disposed at different apertures on the other surface of the lens 31; wherein, the first phase retarder 33 is used to adjust the polarization state of the central field of view light, and the composite film 34 includes at least a polarizing beam splitter and a second phase retarder, etc., for controlling the peripheral field of view light.

[0055] The beam splitter 32 is, for example, a semi-transparent and semi-reflective film, which can transmit a portion of light while reflecting a portion of light.

[0056] The second phase delay film included in the first phase delay film 33 and the composite film 34 are, for example, 1 / 4 wavelength phase films, mainly used to adjust the polarization state of light, such as converting circularly polarized light into linearly polarized light, or vice versa.

[0057] In the optical system provided in this application embodiment, the prism assembly 4 and the first screen 1 are located together on the side of the lens assembly 3 opposite to the second screen 2. The prism assembly 4 mainly consists of a first prism 41, a second prism 42, and a reflective polarizing film 43 located between them. See also Figure 1 and Figure 2 The central field-of-view light emitted from the first screen 1 directly enters the second prism 42, and after total internal reflection, reaches the reflective polarizing film 43. The reflective polarizing film 43 reflects the received central field-of-view light back into the lens 31 for propagation, and finally enters the human eye 01. (See also...) Figure 1 and Figure 3 The edge field of view light emitted by the second screen 2 is reflected and propagated by the lens assembly 3, and then enters the human eye 01 through the prism assembly 4.

[0058] The reflective polarizing film 43 plays a key role in the prism assembly 4. It can selectively reflect and transmit light according to the polarization state of the light, thereby ensuring that the central field of view light and the edge field of view light can both propagate to the human eye 01 along a predetermined path and form a complete image in the human eye 01.

[0059] The optical system provided in this application has at least the following advantages:

[0060] (1) Improve image quality:

[0061] The optical system provided in this application embodiment achieves a perfect fusion of high angular resolution with a small FOV (field of view) in the central field of view region and low angular resolution with a large FOV in the peripheral field of view region. This design greatly improves image quality, ensuring that users can enjoy a clear and complete visual experience when wearing virtual reality devices.

[0062] (2) Simplify the optical structure and reduce the overall thickness of the system:

[0063] The optical system provided in this application embodiment achieves the sharing of optical components between the central field-of-view rays and the peripheral field-of-view rays. This design not only significantly simplifies the complex structure of the optical system and reduces the difficulty of design and manufacturing, but also effectively reduces the overall thickness of the optical system without affecting imaging performance. Furthermore, this application also employs a folded optical path design, enabling the optical system to maintain excellent imaging quality while effectively reducing the overall thickness of the optical system.

[0064] In summary, the optical system design provided in this application helps to make virtual reality devices thinner and more portable, greatly improving the user's wearing comfort and visual experience.

[0065] See some examples in this application. Figure 1 and Figure 4 The beam splitter 32 is disposed on the surface of the lens 31 near the second screen 2; the first phase delay film 33 and the composite film 34 are disposed on the surface of the lens 31 away from the second screen 2, wherein the first phase delay film 33 is located in the middle and the composite film 34 surrounds the periphery of the first phase delay film 33.

[0066] In this example of the application, see Figure 1 and Figure 4 The beam splitter 32 can be deposited or mounted on the surface of the lens 31 near the second screen 2, while the first phase retardation film 33 and the composite film 34 can be attached to different aperture positions on the surface of the lens 31 away from the second screen 2. It is worth noting that the first phase retardation film 33 is designed to be located in the central region of the lens 31, while the composite film 34 is disposed around the periphery of the first phase retardation film 33, i.e., at the edge region of the lens 31.

[0067] The film application method in this example of the application can bring the following technical effects:

[0068] The beam splitter 32 is positioned close to the second screen 2, so that light emitted from the second screen 2 can be directly and effectively processed by the beam splitter 32. The beam splitter 32 is, for example, a semi-transparent and semi-reflective film, which can transmit and reflect part of the light.

[0069] The first phase retardation film 33 and the composite film 34 are disposed on the surface of the lens 31 away from the second screen 2. The first phase retardation film 33 and the composite film 34 (including the second phase retardation film) can adjust the polarization state of light. The two are arranged in sections to ensure that the central field of view light and the edge field of view light can propagate along predetermined paths respectively.

[0070] Regarding clear imaging of the central and peripheral fields of view, specifically:

[0071] The first phase retardation plate 33 is located in the central region of the lens 31, which facilitates precise control of the light in the central field of view. The central field of view typically requires a higher angular resolution (PPD), so by adjusting the polarization state of the light in the central field of view through the first phase retardation plate 33, it can be ensured that the light in the central field of view is projected onto the human eye O1 in the best possible state, forming a high-definition image.

[0072] The composite film 34 is disposed around the periphery of the first phase retarder 33 and is responsible for processing edge field-of-view rays. The composite film 34 includes, for example, a polarizing beam splitter and a second phase retarder, which can adjust the polarization state and propagation direction of the edge field-of-view rays, ultimately enabling a continuous and smooth transition between the edge field of view and the central field of view, providing a wide field of view and a comfortable visual experience.

[0073] In the optical system provided in this application embodiment, the careful arrangement of the beam splitter 32, the first phase retardation film 33, and the composite film 34 on the surface of the lens 31 enables separate control of the central field-of-view rays and the peripheral field-of-view rays, avoiding crosstalk between rays. Furthermore, this film design allows the central field-of-view rays and the peripheral field-of-view rays to share light elements, helping to reduce the overall thickness of the optical system. This allows the virtual reality device to maintain excellent imaging quality while being thinner and more portable, greatly improving user comfort and experience.

[0074] See some examples in this application. Figure 1 , Figure 2 and Figure 4 The central field of view light is emitted from the first screen 1, passes through the second prism 42, is reflected by the reflective polarizing film 43, and is reflected back to the central region of the lens 31. After passing through the second prism 42 and the first prism 41 again, it forms the central field of view image after exiting.

[0075] In this example of the application, see Figure 2 and Figure 4 The propagation path of the light rays in the central field of view is carefully designed to ensure high angular resolution and clear imaging. The specific process is as follows:

[0076] Initial phase: The central field of view light is first emitted from the first screen 1.

[0077] The specific stages of light propagation are as follows:

[0078] The central field of view light emitted from the first screen 1 enters the second prism 42, and the central field of view light undergoes two total internal reflections in the second prism 42.

[0079] The central field-of-view light then reaches the reflective polarizing film 43, which has the function of selective reflection and can reflect or transmit light according to the polarization state of the light. At this stage, light with a specific polarization state (such as S-polarized light) is reflected by the reflective polarizing film 43 to the lens 31.

[0080] The reflected light enters the lens assembly 3 and is reflected back in the central region of the lens assembly 3;

[0081] The light rays, after being refracted and propagated by the lens 31, will re-enter the second prism 42 and then the first prism 41; in these two prisms, the light rays are refracted again, adjusting their propagation direction to match the observation angle of the human eye 01;

[0082] The central field of view light rays are finally emitted to the human eye O1, forming a central field of view image, which has high angular resolution and clear imaging effect.

[0083] See some examples in this application. Figure 1 , Figure 3 and Figure 4 The edge field of view light is emitted from the second screen 2, projected onto the edge area of ​​the lens 31 and propagated back, then passes through the prism assembly 4, and after exiting, forms an edge field of view image that is continuously connected to the central field of view image.

[0084] See Figure 3 and Figure 4 The specific process of the propagation path of the edge field of view light is as follows:

[0085] Initial stage: The edge field of view light is emitted from the second screen 2.

[0086] The second screen 2 is, for example, a large-size display screen that can provide a wide field of view.

[0087] The specific stages of light propagation are as follows:

[0088] The edge field of view light emitted from the second screen 2 enters the lens assembly 3. In the edge region of the lens assembly 3, the edge field of view light is controlled by the beam splitter 32 and the composite film 34, changing its polarization state and propagation path, thus forming a retrograde propagation.

[0089] After being reflected and propagated, the light enters the prism assembly 4, where it is refracted again to ensure that it can be accurately projected onto the human eye 01. After being adjusted by the prism assembly 4, the edge field of view light finally exits to the human eye 01, forming an edge field of view image that is continuously connected with the central field of view image. This edge field of view image has a wide field of view and a visual effect that is continuous with the central field of view.

[0090] See some examples in this application. Figures 1 to 4 The lens 31 is a plano-convex lens, and the surface of the lens 31 near the second screen 2 is convex and aspherical. The beam splitter 32 is disposed on the convex surface of the lens 31. The first phase delay film 33 and the composite film 34 are disposed on the plane of the lens 31.

[0091] In this example of the application, the lens 31 is designed as a plano-convex lens, which is beneficial for focusing light and improving image quality.

[0092] Specifically, see Figure 1 The convex surface of the lens 31 faces the second screen 2. This arrangement can more effectively collect edge field light emitted from the second screen 2 and guide the light onto a predetermined path through the refraction of the convex surface.

[0093] The beam splitter 32 is disposed on the convex surface of the lens 31. Since the convex surface directly faces the second screen 2, this arrangement ensures that the edge field of view light is effectively split when it enters the lens 31, laying the foundation for subsequent optical path folding and propagation.

[0094] In this example of the application, the lens 31 is a plano-convex lens, with a flat surface on the side closer to the human eye 01 and a convex surface (curved surface) on the side closer to the second screen 2.

[0095] In this application, the surface of the lens 31 near the second screen 2 is aspherical. The surface of the lens 31 is designed to be aspherical, and the aspherical formula is as follows:

[0096]

[0097] In the above formula for aspherical surfaces: z is the sag, in mm; r is the distance from the surface to the optical axis, in mm; α is the higher-order term of the aspherical surface; c is the curvature, expressed as the reciprocal of the radius; and k is the Conic coefficient.

[0098] In one example of this application, the design parameters of the lens 31 near the surface of the second screen 2 are as follows:

[0099] c k α1 α2 α3 -0.0146 -0.649 0 -2.302E-7 1.812E-10

[0100] In this application, the beam splitter 32 is, for example, a semi-transparent and semi-reflective film that can transmit a portion of light and reflect another portion of light.

[0101] The first phase retardation film 33 and the composite film 34 are disposed together on the plane of the lens 31 (i.e., the surface away from the second screen 2). This arrangement facilitates further polarization adjustment and beam splitting of the light after beam splitting.

[0102] In this application, the first phase delay film 33 is, for example, a 1 / 4 wavelength phase film, used to adjust the polarization state of light to ensure that the central field of view light can propagate in a predetermined manner.

[0103] In this application, the composite film 34 includes at least a polarizing beam splitter and a second phase delay film, which can further split the edge field of view light and adjust the polarization state of the light.

[0104] The film application method used in this application ensures effective separation of the central field of view rays and the edge field of view rays, avoiding interference and crosstalk between rays, and further improving the imaging quality.

[0105] In this application, a relatively large PPD (pixel density) can be obtained in the central field of view. The phase retardation plate 33 participates in the imaging of the central field of view, and its diameter can be 12 mm. Of course, the central field of view can be set with different field angle ranges, and the diameter of the corresponding phase retardation plate 33 will also change, which is not limited here.

[0106] In this application, the edge field of view (PPD) is relatively small, and the composite film 34 participates in the imaging of the edge field of view, with a diameter of 40 mm. Of course, the edge field of view can be set with different field angle ranges, and the diameter of the composite film 34 will also change accordingly, which is not limited here.

[0107] See some examples in this application. Figure 1 The first prism 41 and the second prism 42 are bonded together, and the reflective polarizing film 43 is located on the bonding surface of the first prism 41 and the second prism 42.

[0108] In this example of the application, an efficient and compact optical structure design is achieved by bonding the first prism 41 and the second prism 42 together and placing the reflective polarizing film 43 on the bonding surface of the two.

[0109] The bonding design of the two prisms enhances the structural stability of the entire prism assembly 4, helping to extend the lifespan of the optical system. The stable structure also helps maintain the consistency of light path propagation, improving the stability and reliability of imaging.

[0110] Placing the reflective polarizing film 43 directly on the bonding surface of the prism simplifies the assembly process of the optical system. This simplified assembly process helps reduce production costs and improve production efficiency.

[0111] See some examples in this application. Figures 1 to 3 The first prism 41 and the second prism 42 are glued together to form a flat plate element; wherein the glued surfaces of the first prism 41 and the second prism 42 form a set angle θ with respect to the optical axis of the lens 31, and the set angle θ is 20°≤θ≤30°.

[0112] When the prism assembly 4 is used as a flat plate element, the thickness of the prism assembly 4 along the optical axis of the lens 31 can be designed to be 5-10mm.

[0113] It should be noted that the tilt angle design of the bonding surfaces of the first prism 41 and the second prism 42 is beneficial to reducing the thickness of the formed prism assembly 4. This allows for minimizing the size of the optical system while ensuring the stability of the entire optical architecture, and simultaneously maintaining image quality.

[0114] In some examples of this application, the first prism 41 and the second prism 42 are made of resin material.

[0115] The first prism 41 and the second prism 42 can be made of the same material. For example, the first prism 41 and the second prism 42 can be made of COC material or COP material.

[0116] Specifically, the refractive index of the first prism 41 and the second prism 42 is 1.54, and the Abbe number is 56.

[0117] See some examples in this application. Figure 1 An air gap is provided between the prism assembly 4 and the lens assembly 3.

[0118] The presence of air gaps allows the prism assembly 4 and the lens assembly 3 to be adjusted in position and angle relatively independently. This flexibility provides more possibilities for the design and optimization of the optical system.

[0119] In addition, the air gap can reduce the reflection and interference effects between the prism assembly 4 and the lens assembly 3, further improving the imaging quality.

[0120] The optical system provided in this application embodiment has an air gap between the prism assembly 4 and the lens assembly 3, which can be set according to different designs.

[0121] In one example of this application, the air gap between the prism assembly 4 and the lens assembly 3 is set to 0.9 mm.

[0122] See some examples in this application. Figure 1 and Figure 2 The central field of view light emitted from the first screen 1 is projected into the second prism 42 and can undergo total internal reflection in the second prism 42 before being projected onto the reflective polarizing film 43.

[0123] In this example of the application, the material and refractive index of the second prism 42 are chosen such that light can undergo two total internal reflections within it.

[0124] Total internal reflection is an optical phenomenon in which light rays travel from a denser medium (a medium with a higher refractive index) to a less dense medium (a medium with a lower refractive index). If the angle of incidence is greater than or equal to the critical angle, the light rays will be completely reflected back into the original medium and will not enter the less dense medium.

[0125] After undergoing two total internal reflections within the second prism 42, the central field-of-view ray is projected onto the reflective polarizing film 43. The reflective polarizing film 43 can selectively reflect and transmit light according to its polarization state. In this example of the application, the reflective polarizing film 43 is used to reflect light of a specific polarization state to the lens assembly 3 to achieve further light manipulation and imaging.

[0126] By achieving total internal reflection in the second prism 42, the central field-of-view light rays can propagate to the reflective polarizing film 43 almost without loss, avoiding light loss and scattering during propagation. This improves light utilization, allowing more light to participate in the imaging process, thereby enhancing the brightness and sharpness of the image.

[0127] Because the central field-of-view rays maintain high energy and polarization consistency during total internal reflection, this helps reduce imaging defects such as aberrations and distortions. Simultaneously, the selective reflection of the reflective polarizing film 43 further enhances the polarization control capability of the light, thereby optimizing image quality.

[0128] In some examples of this application, the composite film 34 further includes a polarizing film, which is stacked sequentially with the polarizing beam splitter and the second phase retarder.

[0129] In this example of the application, the composite film 34 is mainly composed of a polarizing film, a polarizing beam splitter, and a second phase retardation film stacked sequentially. The polarizing film only allows light vibrating in a specific direction to pass through, i.e., it has polarization selectivity. This helps filter out light with non-target polarization states, improving the purity and contrast of the light.

[0130] In some examples of this application, the beam splitter 32 is a semi-transparent and semi-reflective film, and the first phase retarder 33 and the second phase retarder are quarter-wavelength phase films.

[0131] The semi-transparent and semi-reflective film allows some light to pass through while reflecting other light.

[0132] The quarter-wavelength phase film, acting as a phase retardation film, can change the polarization state of light by 90 degrees, such as converting linearly polarized light into circularly polarized light or circularly polarized light into circularly polarized light with the opposite polarization direction. This is crucial for achieving multiple reflections and polarization control of light.

[0133] In some examples of this application, the size of the first screen 1 is smaller than the size of the second screen 2; wherein the size of the first screen 1 is < 0.9 inches.

[0134] In some examples of this application, the first screen 1 is a Micro-OLED screen, and the second screen 2 is a Micro-OLED or LCD screen.

[0135] The first screen 1 can use a high-resolution Micro-OLED, such as a 0.49-inch, 0.71-inch, or 0.83-inch Micro OLED display. In this embodiment, the field of view of the center is, for example, 20° to 30°. Combined with a 1920*1080 resolution Micro OLED, the PPD of the center field of view can reach >60, which fully meets the resolution limit of the human eye.

[0136] The second screen 2 can be a large-size Micro-OLED or LCD, such as a 1.3-1.4 inch micro OLED or a 2.1-2.6 inch LCD screen. In this embodiment, the field of view of the edge is 90°, and combined with a 2280*2280 LCD screen, the PPD of the edge field of view can reach 25.

[0137] The optical system provided in this application has a significant advantage in that the optical paths of the central field of view and the peripheral field of view cleverly share the lens assembly 3 and the prism assembly 4, a design that significantly reduces the thickness of the entire optical system. In this way, the thickness of the optical system is controlled within a compact range of approximately 25mm, which not only optimizes the portability and wearing comfort of the product.

[0138] See Figure 1 and Figure 2 The propagation path of the central field-of-view light emitted from the first screen 1 is as follows:

[0139] The central field-of-view light emitted from the first screen 1 first enters the second prism 42 and undergoes two total internal reflections inside the second prism 42 to ensure that the central field-of-view light propagates along a predetermined path. Subsequently, these lights reach the reflective polarizing film 43, which reflects only the S-polarized light in the central field-of-view light to the lens assembly 3. The lens assembly 3 is composed of a lens 31 (such as a convex lens), a first phase retardation film 33 (such as a 1 / 4 wavelength phase film), and a beam splitter 32 (such as a semi-transparent and semi-reflective film). The first phase retardation film 33 (such as a 1 / 4 wavelength phase film) is attached to the side surface of the lens 31 closest to the prism assembly 4, while the beam splitter 32 (such as a semi-transparent and semi-reflective film) is disposed on the other side surface of the lens 31 away from the prism assembly 4.

[0140] When S-polarized light enters the lens assembly 3, it passes through the first phase retardation film 33 and the beam splitter 32 in sequence. At the beam splitter 32, the light is reflected and then passes through the first phase retardation film 33 again, at which point the polarization state of the light changes. After that, the light encounters the reflective polarizing film 43 again, and after fine adjustment, it is finally projected onto the human eye O1 to form a central field of view image.

[0141] It is worth noting that when light reaches the human eye, its polarization state has changed from the initial S polarization to P polarization. This change is crucial for optimizing image quality and reducing visual interference.

[0142] See Figure 1 and Figure 3 The propagation path of the central field-of-view light emitted from the second screen 2 is as follows:

[0143] The central field-of-view light emitted from the second screen 2 is, for example, right-hand circularly polarized light. It first partially passes through the beam splitter 32 (such as a semi-transparent and semi-reflective film), and the polarization state of the light remains unchanged during this process. Subsequently, the right-hand circularly polarized light enters the composite film 34 and passes through the second phase retardation film (1 / 4 wavelength phase film). Under the action of this film layer, the right-hand circularly polarized light is converted into S-linearly polarized light.

[0144] Next, the S-polarized light encounters and is reflected by the reflective polarizing film 43, and the polarization state remains unchanged during the reflection process; the reflected light passes through the second phase retardation film (1 / 4 wavelength phase film) again, at which point the S-polarized light is converted back into right-hand circularly polarized light; subsequently, the right-hand circularly polarized light encounters and is reflected by the beam splitter 32, and this reflection causes the right-hand circularly polarized light to be converted into left-hand circularly polarized light;

[0145] The left-handed circularly polarized light passes through the second phase retardation film (1 / 4 wavelength phase film) for the third time, and its polarization state is further converted into P-linearly polarized light; this transformation is crucial for the subsequent propagation of light and the final imaging. Finally, after being finely adjusted by the reflective polarizing film 43, the P-linearly polarized light enters the prism assembly 4, where it is refracted at an appropriate angle to ensure that the light can be accurately and efficiently projected onto the human eye O1, forming an image at the edge of the field of view.

[0146] The design of the entire edge field of view optical path fully considers the polarization state conversion and path optimization of light, ensuring high image clarity and low distortion, and providing users with an excellent visual experience.

[0147] According to another aspect of this application, a head-mounted display device is also provided, the head-mounted display device including a housing and an optical system as described above.

[0148] The head-mounted display device provided in this application embodiment can be applied to virtual reality display devices (VR) or mixed reality display devices (MR), etc., and this application does not impose specific limitations on them.

[0149] The above embodiments mainly describe 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. For the sake of brevity, they will not be elaborated here.

[0150] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. An optical system, characterized in that, include: The display component includes a first screen (1) and a second screen (2), wherein the first screen (1) is used to provide a central field of view and the second screen (2) is used to provide an edge field of view. The lens assembly (3) is located on the light-emitting side of the second screen (2). The lens assembly includes at least one lens (31). A beam splitting element (32) is provided on one surface of the lens (31), and a first phase retardation film (33) and a composite film (34) are respectively provided at different apertures on the other surface. The composite film (34) includes at least a polarizing beam splitting film and a second phase retardation film. The prism assembly (4), together with the first screen (1), is located on the side of the lens assembly (3) away from the second screen (2). The prism assembly (4) includes a first prism (41), a second prism (42), and a reflective polarizing film (43) located between the two. The first screen (1) is arranged adjacent to the second prism (42), and the first screen (1) is located on the side of the second prism (42) away from the reflective polarizing film (43).

2. The optical system according to claim 1, characterized in that, The beam splitter (32) is disposed on the surface of the lens (31) near the second screen (2); The first phase delay film (33) and the composite film (34) are disposed on the surface of the lens (31) away from the second screen (2), wherein the first phase delay film (33) is located in the middle and the composite film (34) is disposed around the periphery of the first phase delay film (33).

3. The optical system according to claim 2, characterized in that, The central field of view light is emitted from the first screen (1), passes through the second prism (42), is reflected by the reflective polarizing film (43) to the central region of the lens (31) and propagates back, and then passes through the second prism (42) and the first prism (41) again to form a central field of view image after exiting; The edge field of view light is emitted from the second screen (2), projected onto the edge region of the lens (31) and propagated back, then passes through the prism assembly (4), and after exiting, forms an edge field of view image that is continuously connected with the central field of view image.

4. The optical system according to claim 2, characterized in that, The lens (31) is a plano-convex lens; The surface of the lens (31) near the second screen (2) is convex and aspherical, and the beam splitting element (32) is disposed on the convex surface of the lens (31); The first phase delay film (33) and the composite film (34) are disposed on the plane of the lens (31).

5. The optical system according to claim 1, characterized in that, The first prism (41) and the second prism (42) are bonded together, and the reflective polarizing film (43) is located on the bonding surface of the first prism (41) and the second prism (42).

6. The optical system according to claim 5, characterized in that, The first prism (41) and the second prism (42) are glued together to form a flat plate element of the prism assembly (4); Wherein, the cemented surfaces of the first prism (41) and the second prism (42) form a set angle θ relative to the optical axis of the lens (31), and the set angle θ is 20°≤θ≤30°.

7. The optical system according to claim 6, characterized in that, The first prism (41) and the second prism (42) are made of resin material.

8. The optical system according to claim 1, characterized in that, An air gap is provided between the prism assembly (4) and the lens assembly (3).

9. The optical system according to claim 8, characterized in that, The central field of view light emitted from the first screen (1) is projected into the second prism (42) and can undergo total internal reflection in the second prism (42), and is then projected onto the reflective polarizing film (43).

10. The optical system according to claim 1, characterized in that, The composite film (34) also includes a polarizing film, which is stacked sequentially with the polarizing beam splitter and the second phase delay film.

11. The optical system according to claim 1, characterized in that, The beam splitter (32) is a semi-transparent and semi-reflective film, and the first phase delay film (33) and the second phase delay film are 1 / 4 wavelength phase films.

12. The optical system according to any one of claims 1-11, characterized in that, The size of the first screen (1) is smaller than the size of the second screen (2); The size of the first screen (1) is less than 0.9 inches.

13. The optical system according to claim 12, characterized in that, The first screen (1) is a Micro-OLED screen, and the second screen (2) is a Micro-OLED or LCD screen.

14. A head-mounted display device, characterized in that, include: shell; and The optical system as described in any one of claims 1-13, wherein the optical system is disposed on the housing.

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