Optical system and display device

Abstract

The application discloses an optical system and a display device, relates to the technical field of display, and can improve the ghost problem of near-eye display based on an ultrathin folding light path. The optical system comprises a display panel; a first linear polarizer, a first lens group, a second linear polarizer, a first phase retarder, a second lens group, a second phase retarder, a reflective polarizer, a third lens group and a third linear polarizer are sequentially arranged on the light-emitting side of the display panel, the first lens group is close to the display panel, and the third linear polarizer is away from the display panel.

Description

Technical Field

[0001] This application relates to the field of display technology, and more particularly to an optical system and display device. Background Technology

[0002] Currently, in consumer electronics technologies such as VR (Virtual Reality), AR (Augmented Reality), MR (Mixed Reality), and XR (Extended Reality), a specific optical module is often required to direct the light emitted from the screen onto the human eye, thus presenting a magnified, virtual image to the observer. Traditional virtual reality technology uses a single aspherical surface to magnify the image, but this results in a relatively large system, approximately 50mm thick. With technological advancements, Fresnel lenses have gradually replaced single aspherical surfaces, further reducing the system thickness to around 40mm. Driven by market demand, an ultra-thin folded optical path has been developed, which can significantly reduce the system thickness while enabling smaller, lighter VR products.

[0003] However, in ultra-thin folded optical paths, in addition to the effective signal light incident on the observer's eye, there are often some ineffective lights, which are commonly referred to in the industry as "ghosting," thus affecting the user experience. Summary of the Invention

[0004] This application provides an optical system and display device that can improve the ghosting problem in near-eye displays based on an ultra-thin folded optical path.

[0005] A first aspect of this application provides an optical system comprising:

[0006] Display panel;

[0007] The light-emitting side of the display panel is provided with a first linear polarizer, a first lens group, a second linear polarizer, a first phase retarder, a second lens group, a second phase retarder, a reflective polarizer, a third lens group, and a third linear polarizer in sequence. The first lens group is close to the display panel, and the third linear polarizer is far away from the display panel.

[0008] In some embodiments, a first phase compensation sheet is disposed on the side of the first phase delay sheet away from the display panel; and / or,

[0009] A second phase compensation sheet is provided on the side of the second phase delay sheet away from the display panel.

[0010] In some embodiments, an anti-reflective film is disposed between the second lens group and the second phase retardation film.

[0011] In some embodiments, the surface of the second lens group near the display panel is provided with a semi-transparent, semi-reflective film; and / or,

[0012] The surface of the reflective polarizer is provided with a semi-transparent and semi-reflective film.

[0013] In some embodiments, the transmission axes of the first linear polarizer, the second linear polarizer, and the third linear polarizer are parallel; and / or,

[0014] The transmission axes of the first, second, and third linear polarizers are parallel to a first plane, which is a plane perpendicular to the plane containing the display panel; and / or,

[0015] The angle between the second linear polarizer and the slow axis of the first phase retarder is 45° or 135°, wherein the error of the angle between the second linear polarizer and the slow axis of the first phase retarder is 2°; and / or,

[0016] The angle between the slow axis of the second phase delay plate and the first phase delay plate is 90°, and the error of the angle between the slow axis of the second phase delay plate and the first phase delay plate is 2°.

[0017] In some embodiments, the reflective polarizer is used to reflect light with a vertical polarization state and transmit light with a polarization state parallel to the first plane, wherein the vertical direction is perpendicular to the first plane.

[0018] In some embodiments, the reflective polarizer and the absorption axis of the third linear polarizer are perpendicular to each other.

[0019] In some embodiments, the angle of incidence of the light first incident on the first phase retardation plate is less than or equal to 30°; and / or,

[0020] The angle of incidence of the first incident light on the second phase delay plate is less than or equal to 30°.

[0021] In some embodiments, the focal length of the optical system ranges from 15 mm to 30 mm; and / or,

[0022] The second lens group includes a first sub-lens and a second sub-lens, with the first sub-lens disposed between the third lens group and the second sub-lens. The focal lengths of the first lens group, the second sub-lens, the first sub-lens, the third lens group, and the optical system satisfy the following relationship:

[0023] -620 < (f1-f2) / (f1+f2) < -610;

[0024] -1 < (f3 - f4) / (f3 + f4) < 0;

[0025] -2 < (f1 + f2) × (f3 + f4) / f < -1;

[0026] Wherein, f1 is the focal length of the third lens group, f2 is the focal length of the first sub-lens group, f3 is the focal length of the second sub-lens group, f4 is the focal length of the first lens group, and f is the focal length of the optical system.

[0027] In some embodiments, the second lens group includes a first sub-lens and a second sub-lens, the first sub-lens being disposed between the third lens group and the second sub-lens, and the curvatures of the first lens group, the second sub-lens, the first sub-lens, and the third lens group satisfy the following relationship:

[0028] 95mm <R2<100mm;

[0029] -3 <R5 / R6<-2;

[0030] -2 <R6 / R7<-1;

[0031] -41mm <R10<-40mm;

[0032] Wherein, R2 is the radius of curvature of the surface of the third lens group away from the display panel, R5 is the radius of curvature of the surface of the first sub-lens away from the display panel, R6 is the radius of curvature of the surface of the first sub-lens close to the display panel, R7 is the radius of curvature of the surface of the second sub-lens close to the display panel, and R10 is the radius of curvature of the surface of the first lens group close to the display panel.

[0033] In some embodiments, the diameter of the display area formed by the light rays emitted from the optical system ranges from 4 mm to 10 mm.

[0034] In some embodiments, at least one of the first lens group, the second lens group, and the third lens group includes a single lens, multiple lenses, or a cemented lens; and / or,

[0035] At least one of the first lens group, the second lens group, and the third lens group comprises lenses that are spherical, cylindrical, Fresnel, or freeform surfaces; and / or,

[0036] The lens material of at least one of the first lens group, the second lens group, and the third lens group includes plastic, glass, or a mixture of plastic and glass.

[0037] A second aspect of this application provides a display device, comprising:

[0038] The optical system as described in the first aspect.

[0039] The optical system provided in this application embodiment, by setting multiple lens groups, multiple linear polarizers, and multiple phase retarders, can reduce the deflection angle of the incident and exit optical systems, thereby reducing aberrations and making the light from the exiting optical systems smoother, increasing the effective light source. The reduction in aberrations improves image quality. Specifically, the combination of linear polarizers and lens groups, with lenses of different surface curvatures, allows stray, unwanted light within the optical system to be converted into effective light for exit. Linear polarizers can convert non-circularly polarized light, such as elliptically polarized light or non-circular and non-elliptical polarized light, into linearly polarized light, while phase retarders convert elliptically polarized light or non-circular and non-elliptical polarized light into circularly polarized light. This further converts stray light into effective light for exit, reducing ghosting caused by stray light. Based on existing ultra-thin folded optical paths, this improves display quality and enhances user experience. Furthermore, the newly added lens groups typically do not require stress settings, thus reducing the stress specifications of the lenses in the optical system and lowering the system's cost. Attached Figure Description

[0040] Figure 1 A schematic structural diagram of an optical system provided in an embodiment of this application;

[0041] Figure 2 A schematic structural diagram of another optical system provided in the embodiments of this application;

[0042] Figure 3 A schematic structural diagram of another optical system provided in the embodiments of this application;

[0043] Figure 4 A schematic structural diagram of another optical system provided in the embodiments of this application;

[0044] Figure 5 A schematic structural diagram of an optical system provided in an embodiment of this application;

[0045] Figure 6 A schematic diagram of the MTF curve of an optical system provided in an embodiment of this application;

[0046] Figure 7 This is a schematic structural diagram of a display device provided in an embodiment of this application. Detailed Implementation

[0047] To better understand the technical solutions provided in the embodiments of this specification, the technical solutions of the embodiments of this specification will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this specification and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this specification, rather than limitations on the technical solutions of this specification. In the absence of conflict, the embodiments of this specification and the technical features in the embodiments can be combined with each other.

[0048] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The term "two or more" includes two or more cases.

[0049] Currently, in consumer electronics technologies such as VR, AR, MR, and XR, a specific optical module is often required to direct the light emitted from the screen onto the human eye, thus presenting a magnified, virtual image to the observer. Traditional virtual reality technology uses a single aspherical surface to magnify the image, but this results in a relatively large system, approximately 50mm thick. With technological advancements, Fresnel lenses have gradually replaced single aspherical surfaces, further reducing the system thickness to around 40mm. Driven by market demand, an ultra-thin folded optical path has been developed, which can significantly reduce the system thickness while enabling smaller, lighter VR products. However, in ultra-thin folded optical paths, in addition to the effective signal light incident on the observer's eye, there is often some ineffective light, commonly referred to in the industry as "ghosting," which affects the user experience.

[0050] In view of this, embodiments of this application provide an optical system and display device that can improve the ghosting problem in near-eye displays based on an ultra-thin folded optical path.

[0051] A first aspect of this application provides an optical system. Figure 1 This is a schematic structural diagram of an optical system provided in an embodiment of this application. Figure 1As shown, the optical system provided in this application embodiment includes: a display panel 100; a first linear polarizer 210, a first lens group 310, a second linear polarizer 220, a first phase retarder 410, a second lens group 320, a second phase retarder 420, a reflective polarizer 500, a third lens group 330 and a third linear polarizer 230 are sequentially arranged on the light-emitting side D of the display panel 100, the first lens group 310 being close to the display panel 100 and the third linear polarizer 230 being away from the display panel 100.

[0052] For example, such as Figure 1 As shown, the display light L of the display image is emitted from the light-emitting side D of the display panel 100, and passes sequentially through the first linear polarizer 210, the first lens group 310, the second linear polarizer 220, the first phase delay film 410, the second lens group 320, the second phase delay film 420, and the reflective polarizer 500. Partial reflection occurs on the surface of the reflective polarizer 500 near the display panel 100. The reflected light passes a second time through the second phase delay film 420 and the second lens group 320. Under the reflection of the second lens group 320, it passes a third time through the second lens group 320 and the second phase delay film 420. After passing through the reflective polarizer 500, it passes sequentially through the third lens group 330 and the third linear polarizer 230 before exiting. The exited light can enter the user's viewing side E.

[0053] For example, refer to Figure 1 The imaging principle is as follows: The displayed light ray L passes through the first linear polarizer 210, where its polarization state becomes vertical. This vertically polarized linear light then passes through the first lens group 310, where its polarization state is either linearly polarized or partially linearly polarized. It then passes through the second linear polarizer 220, where its polarization state becomes fully linearly polarized vertically. This linearly polarized light then passes through the first phase retardation plate 410, where its polarization state becomes right-handed circularly polarized. This right-handed circularly polarized light is incident at the incident end of the second lens group 320 and transmitted from the exit end. The transmitted light ray (right-handed circularly polarized or right-handed elliptically polarized) passes through the second phase retardation plate 420, where its polarization state becomes horizontally polarized. Here, the horizontal direction is a plane parallel to the first plane, which is perpendicular to the plane containing the display panel 100. Furthermore… Figure 1The horizontal direction is represented by dots. The horizontally linearly polarized light passes through the reflective polarizer 500 for the first time and is reflected, and its polarization state remains horizontally linearly polarized light. The reflected light passes through the second phase retardation plate 420 for the second time, and its polarization state becomes right-handed circularly polarized light or right-handed elliptically polarized light. It then passes through the second lens group 320 for the second time and is reflected on the surface away from the viewing side E. The reflected light passes through the second lens group 320 for the third time. Due to half-wave loss, the transmitted light becomes left-handed circularly polarized light or left-handed elliptically polarized light. The left-handed circularly polarized light or left-handed elliptically polarized light passes through the second phase retardation plate 420 for the third time and is transmitted, and its polarization state becomes vertically linearly polarized light. The vertically linearly polarized light passes through the reflective polarizer 500 for the second time and is transmitted. The transmitted light then passes through the third lens group 330 and the third linear polarizer 230, and finally enters the observer's eye.

[0054] It should be noted that the first lens group 310, which is close to the display panel 100, does not require stress, while the second lens group 320 and the third lens group 330 do require stress. The remaining phase retardation film and polarizer also require stress. Therefore, the newly added lens group close to the display panel 100 does not require stress, which can reduce costs.

[0055] The optical system provided in this application embodiment, by setting multiple lens groups, multiple linear polarizers, and multiple phase retarders, can reduce the deflection angle of the incident and exit optical systems, thereby reducing aberrations and making the light from the exiting optical systems smoother, increasing the effective light source. The reduction in aberrations improves image quality. Specifically, the combination of linear polarizers and lens groups, with lenses of different surface curvatures, allows stray, unwanted light within the optical system to be converted into effective light for exit. Linear polarizers can convert non-circularly polarized light, such as elliptically polarized light or non-circular and non-elliptical polarized light, into linearly polarized light, while phase retarders convert elliptically polarized light or non-circular and non-elliptical polarized light into circularly polarized light. This further converts stray light into effective light for exit, reducing ghosting caused by stray light. Based on existing ultra-thin folded optical paths, this improves display quality and enhances user experience. Furthermore, the newly added lens groups typically do not require stress settings, thus reducing the stress specifications of the lenses in the optical system and lowering the system's cost.

[0056] In some embodiments, the second lens group 320 is in the refracting optical path, so the optical lens is required to be made of a low-stress material; the first lens group 310 and the third lens group 330 are not in the refracting optical path, so there is no stress requirement for the lens, thus reducing costs.

[0057] For example, the display panel 100 provided in the embodiments of this application may include LCD (liquid crystal display panel), OLED (organic light-emitting diode display), Micro OLED (micro display), MiniLED (mini display), RLCD (reflective liquid crystal display), etc., which are only illustrative and are not intended to limit the specific application.

[0058] In some implementations, the opposite sides of any adjacent optical sheets are bonded together.

[0059] For example, Figure 2 A schematic structural diagram of another optical system provided in an embodiment of this application. (See diagram below.) Figure 2 As shown, the second linear polarizer 220 and the first phase retardation film 410 can be sequentially attached to the side of the first lens group 310 facing away from the display panel 100. Alternatively, the second linear polarizer 220 and the first phase retardation film 410 can be first combined into a single film, and then the combined film can be attached to the side of the first lens group 310 facing away from the display panel 100.

[0060] For example, the second linear polarizer 220 and the first phase delay film 410 can be flat or curved and attached to the side of the first lens group 310 away from the display panel 100.

[0061] In some implementations... Figure 3 This is a schematic structural diagram of another optical system provided in an embodiment of this application. For example... Figure 3 As shown, a first phase compensation plate 710 is disposed on the side of the first phase retardation plate 410 away from the display panel 100, and a second phase compensation plate 720 is disposed on the side of the second phase retardation plate 420 away from the display panel 100. An anti-reflective film 600 is disposed between the second lens group 320 and the second phase retardation plate 420. The first phase compensation plate 710 is used to further compensate for the phase retardation of the first phase retardation plate 410, and the second phase compensation plate 720 is used to further compensate for the phase retardation of the second phase retardation plate 420 to ensure the accuracy of the converted polarization state. Typically, the first phase retardation plate 410 and the second phase retardation plate 420 may have some omissions or stray light in their adjustment of the polarization state of light. Therefore, the first phase compensation plate 710 can correct the phase retardation of the first phase retardation plate 410, and the second phase compensation plate 720 can correct the phase retardation of the second phase retardation plate 420. It can improve the phase difference of light rays incident at large angles on the phase retarder, so that light rays of different angles and wavelengths can obtain a relatively uniform delay on the phase retarder.

[0062] For example, refer to Figure 3 The imaging principle is as follows: when light passes through the first linear polarizer, its polarization state becomes horizontally linearly polarized light. It should be noted that... Figure 3The optical axis of the first linear polarizer shown is... Figure 1 The optical axes of the first linear polarizer shown are orthogonal. Figure 3 The first linear polarizer, designated 211, passes through the first lens group 310, where the light's polarization state is either linearly polarized or partially linearly polarized. It then passes through the second linear polarizer 220, where its polarization state becomes fully linearly polarized in the horizontal direction. The linearly polarized light then passes through the first phase retardation plate 410 and the first phase compensation plate 710, where its polarization state becomes right-handed circularly polarized. The circularly polarized light is transmitted through the second lens group 320. The transmitted light (right-handed circularly polarized or right-handed elliptically polarized) passes through the anti-reflection film 600, the second phase retardation plate 420, and the second phase compensation plate 720, where its polarization state becomes vertically linearly polarized. The vertically polarized light first passes through the reflective polarizer 500 and is reflected, its polarization state remaining vertically linearly polarized. The linearly polarized light then passes through the second phase... The polarization state of the light is changed to right-hand circularly polarized light or right-hand elliptically polarized light by the phase compensation film 720, the second phase retardation film 420 and the antireflection film 600. The light is reflected by the surface near the display panel 100 after passing through the second lens group 320. The light is transmitted through the surface away from the display panel 100 for the third time by the second lens group 320. The transmitted light is changed to left-hand circularly polarized light or left-hand elliptically polarized light. The left-hand circularly polarized light or left-hand elliptically polarized light is transmitted through the antireflection film 600, the second phase retardation film 420 and the second phase compensation film 720 for the third time. The polarization state of the light is changed to horizontal linearly polarized light. The horizontal linearly polarized light is transmitted through the reflective polarizer 500 for the second time. The transmitted light is then transmitted through the antireflection film 600 and the third lens group 330. The transmitted light is then transmitted through the third linear polarizer 230 and finally enters the observer's eye.

[0063] In some implementations... Figure 4 A schematic structural diagram of another optical system provided in an embodiment of this application. For example... Figure 4 As shown, the second phase retardation film 420, the second phase compensation film 720, the reflective polarizer 500, and the antireflective film 600 can be sequentially bonded to the surface of the third lens group 330 near the display panel 100. Alternatively, the second phase retardation film 420, the second phase compensation film 720, the reflective polarizer 500, and the antireflective film 600 can be combined into a single composite and then bonded to the surface of the third lens group 330 near the display panel 100. Alternatively, the second phase retardation film 420, the second phase compensation film 720, the reflective polarizer 500, the antireflective film 600, and the third linear polarizer 230 can be combined into a single composite and then bonded to the surface of the third lens group 330.

[0064] For example, the second phase delay film 420, the reflective polarizer 500, and the antireflective film 600 can be flat or curved and attached to the surface of the third lens group 330 near the display panel 100.

[0065] In some embodiments, a semi-transparent and semi-reflective film is provided on the surface of the second lens group 320 near the display panel 100. A semi-transparent and semi-reflective film is also provided on the surface of the reflective polarizer 500 near the display panel 100. For example, a semi-transparent and semi-reflective film can be provided on the surface of the reflective polarizer 500 near the display panel 100. The semi-transparent and semi-reflective film allows ordinary light to pass through while reflecting the other half, enabling repeated reflections of light within the optical system to form a folded optical path. This allows for the extension of the optical path without increasing the length of the optical system. During the repeated reflections, stray light can be converted into effective light, reducing the light deflection angle, decreasing optical system aberrations, and improving display quality.

[0066] In some implementations, an anti-reflective coating can be applied to the surface of a lens that does not have a translucent / reflective coating to improve light transmittance and reduce light loss.

[0067] In some embodiments, the transmission axes of the first linear polarizer 210, the second linear polarizer 220, and the third linear polarizer 230 are parallel, and their transmission axes are parallel to a first plane, which is a plane perpendicular to the plane containing the display panel 100. The angle between the second linear polarizer 220 and the slow axis of the first phase retardation film 410 is 45° or 135°, wherein the error of the angle between the second linear polarizer 220 and the slow axis of the first phase retardation film 410 is 2°. The angle between the second phase retardation film 420 and the slow axis of the first phase retardation film 410 is 90°, and the error of the angle between the second phase retardation film 420 and the slow axis of the first phase retardation film 410 is 2°. This can further reduce ghosting.

[0068] In some embodiments, the reflective polarizer 500 is used to reflect vertically polarized light and transmit light polarized in a direction parallel to the first plane, with the vertical direction perpendicular to the first plane. The absorption axis of the reflective polarizer 500 is perpendicular to that of the third linear polarizer 230. That is, the reflective polarizer 500 has semi-transparent and semi-reflective properties, and the reflection direction of the reflected light is perpendicular to the transmission axis. Light with a polarization state different from the transmission axis can be reflected into the optical system to continue the reflection path and finally converted into transmittable light, which can reduce ghosting.

[0069] In some embodiments, the angle of incidence of the first incident light beam onto the first phase retardation plate 410 is less than or equal to 30°. The angle of incidence of the first incident light beam onto the second phase retardation plate 420 is less than or equal to 30°. This can further reduce ghosting. Specifically, in the case of incident light beams at a large angle, i.e., incident light beams greater than 30° onto the polarizer, the polarization state deviates from the standard polarization direction during depolarization. For example, refer to... Figure 1The light emitted from the display panel 100 passes through the first linear polarizer 210 and is then transmitted as horizontally polarized light. If the incident angle of the light incident on the first linear polarizer 210 is greater than 30°, the polarization state of the light transmitted through the first linear polarizer 210 may deviate from the horizontal direction, affecting the light emission quality of the overall optical system.

[0070] In some implementations... Figure 5 This is a schematic structural diagram of an optical system provided in an embodiment of this application. Figure 5 As shown, the light L emitted from the display panel 100 undergoes repeated reflections before being emitted again, forming a folded light path. The folded light path enables a short focal length optical system and can improve image ghosting. Figure 5 The second lens group 320 shown includes a first sub-lens 321 and a second sub-lens 322. The first sub-lens 321 can be a concave lens, and the second sub-lens 322 can be a convex lens.

[0071] For example, Figure 6 This is a schematic diagram of the MTF curve of an optical system provided in an embodiment of this application. Figure 6 As shown, MTF (Modulation Transfer Function) uses the concept of contrast to measure the sharpness of a lens. The horizontal axis represents spatial frequency in cycles per mm, with units of lines / mm. The vertical axis represents the Modulus of the OTF (which can be considered as contrast). TS represents the two directional components of light, T represents the vertical component, S represents the sagittal component, and TS Diff.limit is the maximum limit value. For example, TS 0.00 (deg) represents 0° light, and TS 4.50 (deg) represents 4.5° light. Figure 6 Each curve in the diagram corresponds to a field of view. It should be noted that the maximum contrast ratio of the MTF curve of a typical near-eye display optical system is around 0.4 to 0.5, while the contrast ratio of the near-eye display optical system provided in this application embodiment can reach above 0.7, showing a significant improvement in the MTF curve.

[0072] In some implementations, the focal length of the optical system ranges from 15mm to 30mm, such as 28.68mm, 15mm, or 30mm, and the appropriate focal length can be set according to the field of view and the size of the display panel.

[0073] In some implementations, the ratio of the total length of the optical system to half the height of the display panel ranges from 1.5 to 2.5. (See reference) Figure 5The focal length of the third lens group 330 is f1, the focal length of the first sub-lens group 321 is f2, the focal length of the second sub-lens group 322 is f3, the focal length of the first lens group 310 is f4, and the focal length of the optical system is f. Therefore, -620 < (f1 - f2) / (f1 + f2) < -610; -1 < (f3 - f4) / (f3 + f4) < 0; -2 < (f1 + f2) × (f3 + f4) / f < -1.

[0074] In some implementations, the diameter of the display area formed by the light rays emitted from the optical system ranges from 4mm to 10mm. That is, the entrance pupil diameter of the optical system on the user's viewing side E is 4mm, 8mm, or 10mm. This ensures that the entrance pupil diameter of the optical system matches the human eye, while also considering design complexity and cost.

[0075] In some embodiments, at least one of the first lens group 310, the second lens group 320, and the third lens group 330 includes a single lens, multiple lenses, or a cemented lens. The lens of at least one of the first lens group 310, the second lens group 320, and the third lens group 330 includes a spherical, cylindrical, Fresnel, or freeform surface. The lens material of at least one of the first lens group 310, the second lens group 320, and the third lens group 330 includes plastic, glass, or a mixture of plastic and glass.

[0076] For example, with an optical system field of view of 90°, an entrance pupil distance of 8mm, and a focal length of 12mm, Table 1 shows the lens surface parameter data. As shown in Table 1, distance represents the central axial distance from the current surface to the next surface. It should be noted that the optical lens surfaces corresponding to Table 1 can correspond to... Figure 5 The position of the optical element is shown. It should be noted that the protective film of 100 is positioned between 210 and 100.

[0077] Additionally, the radius of curvature of the left surface of 330 can be R2, the radius of curvature of the left surface of 321 is R5, the radius of curvature of the right surface of 321 is R6, the radius of curvature of the right surface of 322 is R7, and the radius of curvature of the right surface of 310 is R10. Therefore, 95mm... <R2<100mm;-3<R5 / R6<-2;-2<R6 / R7<-1;-41mm<R10<-40mm。

[0078]

[0079] Table 1

[0080] For example, the aspherical surface profile height z of an optical lens can be expressed by the following formula, but is not limited to using only the following formula:

[0081]

[0082] Where z is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis; c = 1 / R, where R represents the paraxial radius of curvature of the mirror; k is the conic coefficient; α1, α2, α3 are higher-order aspherical coefficients; ρ is the normalized radial coordinate, i = 1, 2…N, where N is a natural number.

[0083] For example, Table 2 shows the data for higher-order terms of aspherical surfaces.

[0084] Surface number Conic coefficient k coefficient of higher-order term α1 coefficient of higher-order term α2 The coefficient of the higher-order term α3 330 left side surface 12.049 -8.120285E-007 -7.824880E-010 2.681536E-013 321 Left side surface -89.999 -4.413705E-007 5.721644E-010 4.362583E-013 321 right side surface 16.886 -1.270173E-006 -1.314599E-010 4.175574E-013 322 right side surface -10.216 -2.763011E-007 -9.402249E-011 1.437704E-013 310 right side surface -20.478 -2.066201E-006 8.508864E-010 -8.470377E-013

[0085] Table 2

[0086] A second aspect of this application provides a display device. Figure 7 This is a schematic structural diagram of a display device provided in an embodiment of this application. Figure 7 As shown, the display device includes: an optical system 1000 as described in the first aspect.

[0087] The display device provided in this application embodiment may be a VR, AR, MR, XR or other near-eye display device, and this application embodiment does not specifically limit it.

[0088] The display device provided in this application embodiment incorporates multiple lens groups, multiple linear polarizers, and multiple phase retarders in its optical system. Increasing the number of lens groups, linear polarizers, and phase retarders reduces the deflection angles of the incident and exit optical systems, thereby reducing optical system aberrations. This results in smoother light output from the exit optical system, increasing the effective light source and improving image quality. Specifically, the combination of linear polarizers and lens groups, with their varying surface curvatures, allows stray, unwanted light within the optical system to be converted into effective light for exit. Linear polarizers convert non-circularly polarized light, such as elliptically polarized light or non-circular / non-elliptical polarized light, into linearly polarized light. Phase retarders convert elliptically polarized light or non-circular / non-elliptical polarized light into circularly polarized light, further converting stray light into effective light for exit and reducing ghosting caused by stray light. This improves display quality and enhances user experience compared to existing ultra-thin folded optical paths. Furthermore, lens groups typically do not require stress settings, reducing the stress specifications of the lenses in the optical system and lowering its cost.

[0089] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0090] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

[0091] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

[0092] Obviously, those skilled in the art can make various modifications and variations to this specification without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, this specification is also intended to include such modifications and variations.

Claims

1. An optical system, characterized in that, include: Display panel; The light-emitting side of the display panel is provided with a first linear polarizer, a first lens group, a second linear polarizer, a first phase retarder, a second lens group, a second phase retarder, a reflective polarizer, a third lens group, and a third linear polarizer in sequence. The first lens group is close to the display panel, and the third linear polarizer is far away from the display panel. The transmission axes of the first linear polarizer, the second linear polarizer, and the third linear polarizer are parallel; The angle between the second linear polarizer and the slow axis of the first phase retarder is 45° or 135°, wherein the error range of the angle between the second linear polarizer and the slow axis of the first phase retarder is ±2°; and / or, The angle between the slow axis of the second phase delay plate and the first phase delay plate is 90°, and the error range of the angle between the slow axis of the second phase delay plate and the first phase delay plate is ±2°.

2. The optical system according to claim 1, characterized in that, A first phase compensation piece is disposed on the side of the first phase delay piece away from the display panel; and / or, A second phase compensation sheet is provided on the side of the second phase delay sheet away from the display panel.

3. The optical system according to claim 1 or 2, characterized in that, An anti-reflective film is provided between the second lens group and the second phase delay film.

4. The optical system according to claim 1 or 2, characterized in that, The surface of the second lens group near the display panel is provided with a semi-transparent, semi-reflective film; and / or, The surface of the reflective polarizer is provided with a semi-transparent and semi-reflective film.

5. The optical system according to claim 1 or 2, characterized in that, The light transmission axes of the first linear polarizer, the second linear polarizer, and the third linear polarizer are parallel to the first plane, which is a plane perpendicular to the plane where the display panel is located.

6. The optical system according to claim 5, characterized in that, The reflective polarizer is used to reflect light rays polarized in the vertical direction and transmit light rays polarized in a direction parallel to the first plane, wherein the vertical direction is perpendicular to the first plane.

7. The optical system according to claim 5, characterized in that, The absorption axes of the reflective polarizer and the third linear polarizer are perpendicular to each other.

8. The optical system according to claim 1 or 2, characterized in that, The angle of incidence of the first incident light beam onto the first phase retarder is less than or equal to 30°; and / or, The angle of incidence of the first incident light on the second phase delay plate is less than or equal to 30°.

9. The optical system according to claim 1 or 2, characterized in that, The focal length range of the optical system is 15mm to 30mm; and / or, The second lens group includes a first sub-lens and a second sub-lens, with the first sub-lens disposed between the third lens group and the second sub-lens. The focal lengths of the first lens group, the second sub-lens, the first sub-lens, the third lens group, and the optical system satisfy the following relationship: -620 < (f1-f2) / (f1+f2) < -610; -1 < (f3 - f4) / (f3 + f4) < 0; -2 < (f1 + f2) × (f3 + f4) / f < -1; Wherein, f1 is the focal length of the third lens group, f2 is the focal length of the first sub-lens group, f3 is the focal length of the second sub-lens group, f4 is the focal length of the first lens group, and f is the focal length of the optical system.

10. The optical system according to claim 1 or 2, characterized in that, The second lens group includes a first sub-lens and a second sub-lens, with the first sub-lens disposed between the third lens group and the second sub-lens. The curvatures of the first lens group, the second sub-lens, the first sub-lens, and the third lens group satisfy the following relationship: 95mm <R2<100mm; -3 <R5 / R6<-2; -2 <R6 / R7<-1; -41mm <R10<-40mm; Wherein, R2 is the radius of curvature of the surface of the third lens group away from the display panel, R5 is the radius of curvature of the surface of the first sub-lens away from the display panel, R6 is the radius of curvature of the surface of the first sub-lens close to the display panel, R7 is the radius of curvature of the surface of the second sub-lens close to the display panel, and R10 is the radius of curvature of the surface of the first lens group close to the display panel.

11. The optical system according to claim 1 or 2, characterized in that, The diameter of the display area formed by the light emitted from the optical system ranges from 4 mm to 10 mm.

12. The optical system according to claim 1, characterized in that, At least one of the first lens group, the second lens group, and the third lens group includes a single lens, multiple lenses, or a cemented lens; and / or, At least one of the first lens group, the second lens group, and the third lens group comprises lenses that are spherical, cylindrical, Fresnel, or freeform surfaces; and / or, The lens material of at least one of the first lens group, the second lens group, and the third lens group includes plastic, glass, or a mixture of plastic and glass.

13. A display device, characterized in that, include: The optical system as described in any one of claims 1-12.

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