Optical system and head-mounted display device

Abstract

The present invention discloses an optical system and a head-mounted display device, comprising a first lens, a second lens, a third lens, a semi-reflective semi-transmissive film, a first composite film layer, a display screen and a second composite film layer, wherein the first lens comprises a first light-emitting surface and a first light-entering surface; the second lens comprises a second light-emitting surface and a second light-entering surface; the third lens comprises a third light-emitting surface and a third light-entering surface, the first light-entering surface and the second light-emitting surface are engaged with each other, the second light-entering surface and the third light-emitting surface are glued together, the first composite film layer is attached to the surface of the first light-entering surface, the second composite film layer is attached to the display screen, and the light emitted by the display screen is refracted and reflected multiple times in the semi-reflective semi-transmissive film, the third lens, the second lens, the first composite film layer and the first lens, and finally emitted from the first light-emitting surface and merged into the human eye. The advantages of the present invention are that the optical information transmission capability, weight and volume are balanced and taken into consideration, and the optical imaging effect is excellent.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to an optical system and a head-mounted display device. Background Art

[0002] Virtual reality (VR) refers to projecting digital content into the human eye through an optical imaging system. Its essence is to present an object in three-dimensional space that can be observed in real time and without restrictions from the user's perspective, giving the user an immersive experience. The most critical component in VR equipment is the optical imaging system, and the core components of the optical imaging system include the imaging lens (or lens group) and the display screen. The light emitted by the display screen is refracted by the imaging lens and then incident on the pupil of the human eye. The reverse extension line of the light entering the pupil of the human eye converges in the distance to form a virtual image, which is the image seen by the human eye.

[0003] In the prior art, the monocular resolution of mainstream VR and AR virtual display devices is mainly concentrated at around 2K, and the number of lenses is 2-3. However, there is usually a large air gap between the lenses. On the one hand, this will make the total length of the optical module system longer and the size of the optical module larger. On the other hand, when light is transmitted from the air to the lens and from the lens to the air, according to the Fresnel reflection law, the undesired reflection will be higher, resulting in ghosting, glare and other undesirable phenomena. In addition, in the Pancake optical path structure of the VR device, in order to realize the return of light, a polarized reflective device is required. At present, the polarized reflective film is usually attached to the lens in the form of a flat film or a curved film. The film pasting process is prone to cause the film material to stretch, generate bubbles and other defects, and affect the conversion of the polarization state in the optical path.

[0004] In traditional bonding and gluing schemes, the glue layer is easily unevenly distributed, resulting in the optical axes of the two lenses after gluing cannot be well aligned, and the optical axis eccentricity seriously affects the performance of the optical module. There is a risk of cracking of the glue layer during use, which is easy to squeeze the polarizing film material, thereby destroying the uniformity of the film material, making the polarization state conversion in the return light path unsatisfactory, affecting the optical imaging effect; the traditional bonding scheme between lenses is mainly to ensure the eccentricity of the optical axis between lenses when assembling multiple lenses. After the bonding is completed, there are mostly air gaps between the lenses; the gluing scheme between traditional lenses is mostly double gluing, and there are fewer gluing schemes in optical schemes that include polarizing devices, because when gluing lenses that include polarizing devices, not only the optical axis alignment must be ensured, but also the axis alignment between the polarizing devices must be ensured, which is extremely difficult. Summary of the invention

[0005] The present invention provides an optical system and a head-mounted display device, which are used to solve the technical problems that the existing VR devices are difficult to balance and take into account between the optical information transmission capability, weight and volume, and the traditional joint and gluing solutions have poor optical imaging effects.

[0006] In order to solve the above technical problems, the present invention discloses the following technical solutions:

[0007] The present invention provides an optical system, comprising a first lens, a second lens, a third lens, a semi-reflective and semi-transmissive film, a first composite film layer, a display screen and a second composite film layer.

[0008] The first lens comprises a first light emitting surface and a first light incident surface which are opposite to each other, and the first lens further comprises a first ridge surface and a first base surface; the second lens comprises a second light emitting surface and a second light incident surface which are opposite to each other, the second light emitting surface is arranged opposite to the first light incident surface, the second lens further comprises a second ridge surface and a second base surface, there is a gap between the first lens and the second lens, the first ridge surface is bonded to the second ridge surface, and the gap is filled with an optical liquid; the third lens comprises a third light emitting surface and a third light incident surface which are opposite to each other, the third light emitting surface is bonded to the second light incident surface; the semi-reflective and semi-transparent film is bonded to the surface of the third light incident surface; the first composite film layer is located between the first lens and the second lens, the first composite film layer is bonded to on the surface of the first light incident surface; the display screen is arranged opposite to the third light incident surface; the second composite film layer is located between the third lens and the display screen, and the second composite film layer is attached to the side of the display screen facing the third lens; wherein the light emitted by the display screen is converted into a first circularly polarized light by the second composite film layer; the first circularly polarized light passes through the semi-reflective and semi-transparent film, the third lens and the second lens in sequence and is incident on the first composite film layer; the first circularly polarized light is reflected by the first composite film layer to form a second circularly polarized light; the second circularly polarized light is reflected by the semi-reflective and semi-transparent film to form a third circularly polarized light; the third circularly polarized light passes through the third lens, the second lens, the first composite film layer and the first lens in sequence and is emitted.

[0009] Furthermore, the first composite film layer includes a first polarizer, a first phase retarder and a polarized reflective plate, the first polarizer is arranged opposite to the first light incident surface of the first lens; the first phase retarder is arranged opposite to the second light emitting surface of the second lens; one side of the polarized reflective plate is bonded to the first polarizer, and the other side thereof is bonded to the first phase retarder; when the first circularly polarized light is incident on the first composite film layer, the first circularly polarized light is converted into a first linear polarized light by the first phase retarder; the first linear polarized light is reflected by the polarized reflective plate, and is converted into a second circularly polarized light by the first phase retarder.

[0010] Furthermore, the second composite film layer includes a protective film, a second phase retarder, a second polarizer and a release film.

[0011] The first surface of the protective film is arranged opposite to the third light incident surface of the third lens; the first surface of the second phase retarder is adhered to the second surface of the protective film; the first surface of the second polarizer is adhered to the second surface of the second phase retarder; one surface of the release film is adhered to the second surface of the second polarizer, and the other surface thereof is attached to the side of the display screen facing the third lens; when the light emitted by the display screen enters the second composite film layer, the light is converted into polarized light by the second polarizer after passing through the release film; the polarized light is converted into first circularly polarized light by the second phase retarder and emitted through the protective film.

[0012] Furthermore, the length of the first step surface is greater than the length of the second step surface, and the length of the contact surface between the first step surface and the second step surface is in the range of 0.2 to 1 mm.

[0013] Furthermore, the first cam surface, the first base surface and the first light incident surface are on the same side of the first lens, there is a rounded corner at the junction of the first cam surface and the first base surface, the radius of the rounded corner is 0.2 mm, and the angle between the first cam surface and the first base surface ranges from 10° to 40°; the second cam surface, the second base surface and the second light exit surface are on the same side of the second lens, there is a rounded corner at the junction of the second cam surface and the second base surface, the radius of the rounded corner is 0.2 mm, and the angle between the second cam surface and the second base surface ranges from 10° to 40°.

[0014] Furthermore, the refractive index range of the optical liquid is (n min -0.2)~(n max +0.2), where n min is the minimum refractive index of the first cantilever surface, n max is the maximum refractive index of the first cantilever surface.

[0015] Further, the first light emitting surface is a plane, a concave surface or a convex surface, and the curvature range of the first light emitting surface is -0.2~0.1 / mm, wherein the central part of the first light emitting surface is a convex surface, and the curvature range of the central part of the first light emitting surface is 0~0.1 / mm; the edge part of the first light emitting surface is a concave surface,

[0016] The curvature range of the edge portion of the first light emitting surface is -0.2~0 / mm; the first light incident surface is a convex surface, and the curvature range of the first light incident surface is -0.4~0.1 / mm.

[0017] Furthermore, the second light emitting surface is a concave surface, and the curvature range of the second light emitting surface is -0.2~0.3 / mm; the second light incident surface is a convex surface, and the curvature range of the second light incident surface is -0.4~0.1 / mm.

[0018] Furthermore, the third light emitting surface is a concave surface, and the curvature range of the third light emitting surface is -0.2~0.3 / mm; the third light incident surface is a convex surface, and the curvature range of the third light incident surface is -0.1~0.1 / mm.

[0019] The present invention also provides a head-mounted display device, wherein the head-mounted device comprises the optical system.

[0020] Compared with the prior art, the present invention has at least the following technical effects:

[0021] The present application provides an optical system and a head-mounted display device, which utilizes a combination of a first lens, a second lens, and a third lens to improve the optical information transmission capability of the head-mounted display device. At the same time, a first polarizer, a polarizing reflector, and a first phase delay plate are glued between the first lens and the second lens, and a semi-reflective and semi-transparent film is attached to the side of the third lens facing the screen, which can ensure that the image height is effectively reduced under the premise of a larger field of view FOV, so as to adapt to the miniaturized design of the head-mounted display device.

[0022] The first lens and the second lens that are combined can reduce ghosting and glare caused by undesired reflections at the interface of the materials, improve the contrast of the image transmitted by the optical imaging device, and further enhance the optical information transmission capability of the head-mounted display device. In addition, during the combination operation, the liquid with good fluidity and optical properties is filled, which not only realizes the eccentricity control of the optical axis between the first lens and the second lens, but also takes into account the advantages of the bonding process and reduces the difficulty of bonding multiple lenses.

[0023] The glued second lens and the third lens can reduce the ghost and glare caused by the undesired reflection at the material interface, improve the contrast of the image transmitted by the optical imaging device, and further enhance the optical information transmission capability of the head-mounted display device. In addition, the glued connection method can increase the stability of the overall structure of the optical imaging device and reduce the total length of the optical system of the optical imaging device to further reduce the problems of ghost and glare, and at the same time facilitate the miniaturization and lightweight design of the head-mounted display device.

[0024] The functional film material of the semi-reflective and semi-transparent film glued to the third lens and the first composite film layer between the first lens and the second lens can be adapted to the light path transmission of the optical imaging device, so that the optical imaging device can reduce the main light emission angle CRA entering the human eye under the premise of a larger field of view, avoiding the user from observing obvious color deviation. At the same time, the above-mentioned film material can also increase the stability of film material adhesion during the gluing process, while reducing the risk of film material falling off and warping, and improving the accuracy and stability of optical imaging device assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] Figure 1 A schematic diagram of the structure of an optical system according to an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of a partial structure of an optical system according to an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of an exploded structure of an optical system according to an embodiment of the present invention;

[0029] Figure 4 is a schematic structural diagram of the second composite film layer according to an embodiment of the present invention;

[0030] Figure 5 is a schematic structural diagram of the first composite film layer according to an embodiment of the present invention;

[0031] Figure 6 is a curvature cross-sectional diagram of a first light-emitting surface of a first lens according to an embodiment of the present invention;

[0032] Figure 7 A curvature cross-sectional diagram of the first light incident surface and the second light emitting surface according to an embodiment of the present invention;

[0033] Figure 8 A curvature cross-sectional view of the second light incident surface and the third light emitting surface according to an embodiment of the present invention;

[0034] Fig. 9is a curvature cross-sectional diagram of a third light incident surface of the third lens according to an embodiment of the present invention;

[0035] Fig.10 A light dot diagram of the optical system according to an embodiment of the present invention;

[0036] Fig.11 A modulation transfer function diagram of an optical system according to an embodiment of the present invention;

[0037] Fig.12 A schematic diagram of field curvature and distortion of an optical system according to an embodiment of the present invention.

[0038] The components in the figure are identified as follows:

[0039] 10 first lens, 20 second lens, 30 third lens, 40 semi-reflective semi-transmissive film, 50 first composite film layer, 60 display screen, 70 second composite film layer, 80 gap;

[0040] 11 first light emitting surface, 12 first light incident surface, 13 first ridge surface, 14 first base surface;

[0041] 21 second light emitting surface, 22 second light incident surface, 23 second ridge surface, 24 second base surface;

[0042] 31 third light emitting surface, 32 third light incident surface;

[0043] 51 a first polarizing plate, 52 a first phase retarder, 53 a polarizing reflector;

[0044] 71 protective film, 72 second phase delay plate, 73 second polarizing plate, 74 release film. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] In the drawings, components with the same structure are indicated by the same numerical labels, and components with similar structures or functions are indicated by similar numerical labels. Directional terms mentioned in the present invention, such as up, down, front, back, left, right, inside, outside, upper surface, lower surface, side, top surface, bottom, front end, rear end, end, etc., are only directions in the drawings and are only used to explain and illustrate the present invention, but not to limit the scope of protection of the present invention.

[0047] In the drawings, components with the same structure are indicated by the same numerical reference numerals. When some components are described as being "on" another component, the component may be directly placed on the other component; there may also be an intermediate component on which the component is placed, and the intermediate component is placed on the other component. When a component is described as being "mounted to" or "connected to" another component, the two may be understood to be directly "mounted" or "connected", or one component may be indirectly "mounted to" or "connected to" another component through an intermediate component.

[0048] The present application provides an optical system and a head-mounted display device, which are described in detail below. It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments of the present application. In the following embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0049] like Figure 1 As shown, the present application provides an optical system, which can be applicable to head-mounted display devices, such as virtual reality devices (VR), augmented reality devices (AR), virtual display devices (XR), mixed reality devices (MR) and other electronic devices. In this application, VR devices are used as examples for explanation.

[0050] In the prior art, the chief ray angle CRA (chief ray angle) of the optical system of VR devices is too large, which causes the human eye to observe obvious color deviation, making the hue and saturation of a certain color in the image entering the human eye obviously different from the real image. At the same time, the optical system always has impure polarization states, which leads to ghosting and glare problems caused by non-ideal imaging entering the human eye, making the VR device weak in transmitting optical information to high-resolution screens, and the imaging quality does not meet the requirements, and the advantages of high-resolution screens cannot be brought into play.

[0051] Since the optical information transmission capability is determined by factors such as the specific material, quantity, and surface shape of each optical element in the optical system, a balance between the optical information transmission capability and the weight and volume of the VR device can be achieved by reasonably configuring the material properties of each optical element in the optical system, the quantity of optical elements, surface parameters, and the positional relationship between different optical elements.

[0052] However, in traditional bonding and gluing solutions, the glue layer is easily unevenly distributed, resulting in the optical axes of the two lenses not being well aligned after gluing, causing optical axis eccentricity that seriously affects the performance of the optical module. There is a risk of cracking of the glue layer during use, and it is easy to squeeze the polarizing film material, thereby destroying the uniformity of the film material, making the polarization state conversion in the return light path unsatisfactory, affecting the optical imaging effect.

[0053] like Figure 1-Figure 3 As shown, the present invention provides an optical system based on a new type of coupling method, and the optical system includes a first lens 10, a second lens 20, a third lens 30, a semi-reflective and semi-transparent film 40, a first composite film layer 50, a display screen 60 and a second composite film layer 70.

[0054] The first lens 10 includes a first light emitting surface 11 and a first light incident surface 12 which are opposite to each other. The first lens 10 also includes a first ridge surface 13 and a first base surface 14. The first ridge surface 13 and the first base surface 14 are located at the edge of the first lens 10. The first ridge surface 13, the first base surface 14 and the first light incident surface 12 are located on the same side of the first lens 10. The first ridge surface 13 is located between the two first base surfaces 14. Both sides of the first ridge surface 13 are connected to the two first base surfaces 14 respectively. The second lens 20 includes a second light emitting surface 21 and a second light incident surface 22 which are opposite to each other. The second light emitting surface 21 is arranged opposite to the first light incident surface 12. The second lens 20 also includes a second ridge surface 23 and a second base surface 24. The second ridge surface 23 and the second base surface 24 are located at the edge of the second lens 20. The second ridge surface 23, the second base surface 24 and the second light emitting surface 21 are located on the same side of the second lens 20. The second ridge surface 23 is located between the two second base surfaces 24. The two sides of the second ridge surface 23 are respectively connected to the two second base surfaces 24, there is a gap 80 between the first lens 10 and the second lens 20, the first ridge surface 13 is attached to the second ridge surface 23, a first base surface 14 is attached to a second base surface 24, and there is a gap 80 between the other first base surface 14 and the other second base surface 24, and the gap 80 is filled with optical liquid; the third lens 30 includes a third light emitting surface 31 and a third light incident surface 32 which are opposite to each other, and the third light emitting surface 31 is attached to the second light incident surface 22; the semi-reflective and semi-transparent film 40 is attached to the surface of the third light incident surface 32; the first composite film layer 50 is located between the first lens 10 and the second lens 20, and the first composite film 50 layer is attached to the surface of the first light incident surface 12; the display screen 60 is arranged opposite to the third light incident surface 32; the second composite film layer 70 is located between the third lens 30 and the display screen 60, and the second composite film layer 70 is attached to the side of the display screen 60 facing the third lens 30.

[0055] like Figure 4 As shown, the first composite film layer 50 includes a first polarizer 51, a first phase retarder 52 and a polarized reflective plate 53. The first polarizer 51 is arranged opposite to the first light incident surface 12 of the first lens 10; the first phase retarder 52 is arranged opposite to the second light emitting surface 21 of the second lens 20; one side of the polarized reflective plate 53 is bonded to the first polarizer 51, and the other side of the polarized reflective plate 53 is bonded to the first phase retarder 52.

[0056] like Figure 5As shown, the second composite film layer 70 includes a protective film 71 , a second phase retarder 72 , a second polarizer 73 and a release film 74 .

[0057] The first surface of the protective film 71 is arranged opposite to the third light incident surface 32 of the third lens 30; the first surface of the second phase retarder 72 is bonded to the second surface of the protective film 71, the first surface of the protective film 71 is a side surface close to the third lens 30, and the second surface of the protective film 71 is a side surface away from the third lens 30; the first surface of the second polarizer 73 is bonded to the second surface of the second phase retarder 72; one surface of the release film 74 is bonded to the second surface of the second polarizer 73, and the other surface of the release film 74 is attached to the side of the display screen 60 facing the third lens 30, the first surface is a side surface close to the third lens 30, and the second surface is a side surface away from the third lens 30.

[0058] The light emitted by the display screen 60 is converted into a first circularly polarized light by the second composite film layer 70. When the light emitted by the display screen 60 enters the second composite film layer 70, the light passes through the release film 74 and is converted into a polarized light by the second polarizer 73. The polarized light is converted into a first circularly polarized light by the second phase retarder 72 and is emitted through the protective film 71. The first circularly polarized light passes through the semi-reflective and semi-transmissive film 40, the third lens 30 and the second lens 20 in sequence and enters the first composite film layer 50. The first circularly polarized light is converted into a first circularly polarized light by the second composite film 73. After being reflected by the layer 50, a second circularly polarized light is formed. When the first circularly polarized light is incident on the first composite film layer 50, the first circularly polarized light is converted into a first linear polarized light by the first phase retarder 52; the first linear polarized light is reflected by the polarizing reflective plate 53, and is converted into a second circularly polarized light by the first phase retarder 52; the second circularly polarized light is reflected by the semi-reflective and semi-transparent film 40 to form a third circularly polarized light; the third circularly polarized light is emitted through the third lens 30, the second lens 20, the first composite film layer 50 and the first lens 10 in sequence.

[0059] In this embodiment, the polarization state of the first circularly polarized light is circularly polarized light, and the polarization state of the light becomes linear polarized light with a vibration direction parallel to the incident plane, which is the first linear polarized light. The polarization state of the second circularly polarized light is circularly polarized light, and the polarization state of the light becomes circularly polarized light with an opposite rotation direction, which is the third circularly polarized light. The polarization state of the light becomes linear polarized light with a vibration direction perpendicular to the incident plane, which is the second linear polarized light.

[0060] In this embodiment, since the incident angle of the optical imaging device must be circularly polarized light, it is necessary to determine whether a composite film layer needs to be added in front of the screen and the specific composition of the composite film layer based on the light emitted by the display screen 60.

[0061] like Figure 5As shown, when the light emitted by the display screen 60 is natural light, a second composite film layer 70 is arranged between the display screen 60 and the optical imaging device. The display screen 60 can be an OLED screen. The light emitted by the display screen 60 is non-polarized light. The second polarizer 73 is used to convert the light into polarized light, and then the second phase delay plate 72 is used to convert the polarized light into circularly polarized light.

[0062] When the light emitted by the display screen 60 is circularly polarized light, a third composite film (not shown) is provided between the display screen 60 and the optical imaging device. The third composite film comprises a second release film, a third phase retarder, a third polarizer, a fourth phase retarder and a second protective film which are sequentially arranged and connected, and the second release film is bonded to the screen of the display screen. The light emitted by the display screen 60 is circularly polarized light, the third phase retarder is used to convert the light into linearly polarized light, the third polarizer is used to filter the linearly polarized light, and the fourth phase retarder is used to convert the linearly polarized light into circularly polarized light.

[0063] In addition, when the light emitted by the display screen 60 is circularly polarized light, the third composite film may not be added between the display screen 60 and the third lens 30 .

[0064] Therefore, the specific path of light propagation is as follows: the light emitted by the display screen 60 is converted into a first circularly polarized light by the second composite film layer 70, the first circularly polarized light passes through the semi-reflective and semi-transmissive film 40, the third lens 30 and the second lens 20 in sequence and is incident on the first composite film layer 50, the first circularly polarized light passes through the first phase retarder 52 and is converted into a first linearly polarized light, the first linearly polarized light is reflected by the polarizing reflective film 53 and is converted into a second circularly polarized light by the first phase retarder 52, and then the second circularly polarized light passes through the second lens 20, the third lens 30 and the semi-transmissive film 40 in sequence and is incident on the first composite film layer 50, The semi-transparent film 40 is reflected by the semi-transparent film 40 to form a third circularly polarized light. At this time, the second circularly polarized light passes through the third lens 30 and the second lens 20 in sequence and is incident on the first composite film layer 50. When the second circularly polarized light enters the first phase retarder 52, the second circularly polarized light is converted into a second linear polarized light by the first phase retarder 52. The second linear polarized light can pass through the polarizing reflective plate 53. The second linear polarized light passes through the polarizing reflective plate 53, the first polarizing plate 51 and the first lens 10 in sequence and enters the human eye.

[0065] In this embodiment, the length of the first ridge surface 13 is greater than the length of the second ridge surface 23, and the length range of the contact surface between the first ridge surface 13 and the second ridge surface 23 is 0.2-1 mm. In this embodiment, the length range of the contact surface between the first ridge surface 13 and the second ridge surface 23 is 0.5 mm.

[0066] Furthermore, the first cam surface 13, the first base surface 14 and the first light incident surface 12 are on the same side, and the angle between the first cam surface 13 and the first base surface 14 is in the range of 10°-40°; the second cam surface 23, the second base surface 24 and the second light emitting surface 21 are on the same side, and the angle between the second cam surface 23 and the second base surface 24 is in the range of 10°~40°. In the present embodiment, the angle between the first cam surface 13 and the first base surface 14 is 30°, and the angle between the second cam surface 23 and the second base surface 24 is also 30°.

[0067] Furthermore, there is a rounded corner at the junction of the first ridge surface 13 and the first base surface 14, and the radius of the rounded corner is 0.2 mm; there is a rounded corner at the junction of the second ridge surface 23 and the second base surface 24, and the radius of the rounded corner is 0.2 mm.

[0068] Furthermore, the refractive index range of the optical liquid is (n min -0.2)~(n max +0.2), where n min is the minimum refractive index of the first cantilever surface, n max is the maximum refractive index of the first ridge surface. In this embodiment, the optical liquid is optical glue, and the refractive index of the optical glue is 1.49, which can effectively reduce the ghost and glare caused by the undesired reflection at the material interface of the first lens 10, the first composite film layer 50 and the second lens 20. At the same time, the first composite film 700 is glued between the first lens 10 and the second lens 20, which can increase the stability of the film material adhesion, thereby reducing the risk of the film material falling off and warping.

[0069] like Figure 1 as well as Figure 6-Figure 7 As shown, the first light emitting surface 11 is a plane, a concave surface or a convex surface, and the curvature range of the first light emitting surface is -0.2~0.1 / mm, wherein the central part of the first light emitting surface 11 is a convex surface, and the curvature range of the central part of the first light emitting surface 11 is 0~0.1 / mm; the edge part of the first light emitting surface is a concave surface, and the curvature range of the edge part of the first light emitting surface is -0.2~0 / mm, so that the first light emitting surface 11 can effectively reduce the main light incidence angle CRA entering the human eye and avoid color deviation under the premise of a larger field of view FOV; and can also ensure the image quality of the edge field of view; the first light incident surface 12 is a convex surface, and the curvature range of the first light incident surface 12 is -0.4~0.1 / mm. The head-mounted display device is prone to cause the main light incidence angle CRA of the light entering the human eye on the screen to be larger under the premise of a large field of view, which is easy to cause color deviation. Therefore, by limiting the curvatures of the first light incident surface 12 and the first light emitting surface 11 , the chief light incidence angle CRA entering the human eye can be effectively reduced, thereby avoiding the phenomenon of color shift.

[0070] like Figure 1 as well as Figure 7 - Figure 8 As shown, the second light emitting surface 21 is a concave surface, and the curvature range of the second light emitting surface 21 is -0.2~0.3 / mm; the second light incident surface 22 is a convex surface, and the curvature range of the second light incident surface 22 is -0.4~0.1 / mm.

[0071] like Figure 1 as well as Figure 8 - Fig. 9 As shown, the third light emitting surface 31 is a concave surface, and the curvature range of the third light emitting surface 31 is -0.2~0.3 / mm; the third light incident surface 32 is a convex surface, and the curvature range of the third light incident surface 32 is -0.1~0.1 / mm.

[0072] In this embodiment, the connection method of ensuring that the second light incident surface 22 and the third light emitting surface 31 are glued together can increase the stability of the overall structure of the optical imaging device, and can reduce the total length of the optical system of the optical imaging device to further reduce the problems of ghosting and glare, while facilitating adaptation to the miniaturization and lightweight design of the head-mounted display device.

[0073] In this embodiment, the first lens 10, the second lens 20, and the third lens 30 are all injection-molded lenses. For specific parameters, please refer to Table 1:

[0074] Table 1 Parameters of the lens in the optical imaging device in Example 1

[0075]

[0076]

[0077] Among them, z represents the sagittal height along the optical axis when the distance from any point on the surface to the vertex is r when the surface type is an even aspheric surface; c = 1 / R, R is the radius of curvature of the surface; A2, A4, A6, etc. are even aspheric coefficients; i=2,4,6...N, N is an even number.

[0078] See also Fig.10 The light dot pattern shows that the imaging light of the optical imaging device is well converged near the main light, and the size of the formed light spot is close to that of the Airy disk.

[0079] See also Fig.11 The relationship between the MTF value and the spatial frequency in the modulation transfer function diagram is that when the spatial frequency is within 80lp / mm, the MTF curve transitions smoothly, and at 80lp / mm, the MTF value of most of the field of view is still greater than 0.5, and the minimum MTF value is greater than 0.1.

[0080] See also Fig.12Schematic diagram of mid-field curvature and distortion. Both the meridian field curvature and sagittal field curvature are controlled within 0.2mm.

[0081] The advantages of the present invention are that an optical system and a head-mounted display device are provided, and the optical information transmission capability of the head-mounted display device is improved by combining a first lens, a second lens, and a third lens. At the same time, a first polarizer, a polarizing reflector, and a first phase delay plate are glued between the first lens and the second lens, and a semi-reflective and semi-transmissive film is attached to the side of the third lens facing the screen, which can ensure that the image height is effectively reduced under the premise of a large field of view FOV, so as to adapt to the miniaturized design of the head-mounted display device.

[0082] The first lens and the second lens that are combined can reduce ghosting and glare caused by undesired reflections at the interface of the materials, improve the contrast of the image transmitted by the optical imaging device, and further enhance the optical information transmission capability of the head-mounted display device. In addition, during the combination operation, the liquid with good fluidity and optical properties is filled, which not only realizes the eccentricity control of the optical axis between the first lens and the second lens, but also takes into account the advantages of the bonding process and reduces the difficulty of bonding multiple lenses.

[0083] The glued second lens and third lens can reduce ghosting and glare caused by undesired reflections at the interface of the materials, improve the contrast of the image transmitted by the optical imaging device, and further enhance the optical information transmission capability of the head-mounted display device. In addition, the glued connection method can increase the stability of the overall structure of the optical imaging device and reduce the total length of the optical system of the optical imaging device to further reduce the problems of ghosting and glare, and at the same time facilitate the miniaturization and lightweight design of the head-mounted display device.

[0084] The functional film material of the semi-reflective and semi-transparent film glued to the third lens and the first composite film layer between the first lens and the second lens can be adapted to the light path transmission of the optical imaging device, so that the optical imaging device can reduce the main light emission angle CRA entering the human eye under the premise of a larger field of view, avoiding the user from observing obvious color deviation. At the same time, the above-mentioned film material can also increase the stability of film material adhesion during the gluing process, while reducing the risk of film material falling off and warping, and improving the accuracy and stability of optical imaging device assembly.

[0085] An optical system and a head-mounted display device provided by an embodiment of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present invention. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical system, characterized in that: include: A first lens, comprising a first light emitting surface and a first light incident surface which are opposite to each other, and the first lens further comprises a first cantilever surface and a first base surface; The first light emitting surface is a plane, a concave surface or a convex surface, and the curvature range of the first light emitting surface is -0.2~0.1 / mm, wherein the central part of the first light emitting surface is a convex surface, and the curvature range of the central part of the first light emitting surface is 0~0.1 / mm; The edge portion of the first light emitting surface is a concave surface, and the curvature range of the edge portion of the first light emitting surface is -0.2~0 / mm; The first light incident surface is a convex surface, and the curvature range of the first light incident surface is -0.4~0.1 / mm; a second lens, comprising a second light emitting surface and a second light incident surface which are opposite to each other, the second light emitting surface being arranged opposite to the first light incident surface, the second lens further comprising a second ridge surface and a second base surface, a gap being present between the first lens and the second lens, the first ridge surface being attached to the second ridge surface, and the gap being filled with an optical liquid; The second light emitting surface is a concave surface, and the curvature range of the second light emitting surface is -0.2~0.3 / mm; The second light incident surface is a convex surface, and the curvature range of the second light incident surface is -0.4~0.1 / mm; A third lens, comprising a third light emitting surface and a third light incident surface which are opposite to each other, wherein the third light emitting surface is bonded to the second light incident surface; The third light emitting surface is a concave surface, and the curvature range of the third light emitting surface is -0.2~0.3 / mm; The third light incident surface is a convex surface, and the curvature range of the third light incident surface is -0.1~0.1 / mm; A semi-reflective and semi-transparent film is attached to the surface of the third light incident surface; A first composite film layer, which is located between the first lens and the second lens, and the first composite film layer is attached to a surface of the first light incident surface; a display screen, arranged opposite to the third light incident surface; and a second composite film layer, which is located between the third lens and the display screen, and the second composite film layer is attached to a side of the display screen facing the third lens; Wherein, the optical system comprises three lenses, and the light emitted by the display screen is converted into first circularly polarized light by the second composite film layer; The first circularly polarized light passes through the semi-reflective and semi-transmissive film, the third lens and the second lens in sequence and is incident on the first composite film layer; After the first circularly polarized light is reflected by the first composite film layer, a second circularly polarized light is formed; After the second circularly polarized light is reflected by the semi-reflective and semi-transmissive membrane, a third circularly polarized light is formed; The third circularly polarized light is emitted through the third lens, the second lens, the first composite film layer and the first lens in sequence.

2. The optical system according to claim 1, wherein: The first composite film layer comprises: a first polarizer, disposed opposite to the first light incident surface of the first lens; a first phase retarder, arranged opposite to the second light-emitting surface of the second lens; and A polarizing reflective plate, one side of which is bonded to the first polarizing plate, and the other side of which is bonded to the first phase retarder; When the first circularly polarized light is incident on the first composite film layer, The first circularly polarized light is converted into a first linearly polarized light by the first phase retarder; The first linearly polarized light is reflected by the polarization reflective plate and converted into second circularly polarized light by the first phase retarder.

3. The optical system according to claim 1, wherein: The second composite film layer comprises: a protective film, a first surface of which is arranged opposite to the third light incident surface of the third lens; A second phase retarder, a first surface of which is bonded to the second surface of the protective film; A second polarizer, a first surface of which is bonded to a second surface of the second phase retarder; and a release film, one side of which is attached to the second side of the second polarizer, and the other side of which is attached to the side of the display screen facing the third lens; When the light emitted by the display screen enters the second composite film layer, After passing through the release film, the light is converted into polarized light by the second polarizer; The polarized light is converted into a first circularly polarized light by the second phase retarder and is emitted through the protective film.

4. The optical system according to claim 1, wherein: The length of the first step surface is greater than that of the second step surface, and the length of the contact surface between the first step surface and the second step surface is in the range of 0.2 to 1 mm.

5. The optical system according to claim 1, wherein: The first ridge surface, the first base surface and the first light incident surface are on the same side of the first lens, a fillet is formed at the junction of the first ridge surface and the first base surface, the radius of the fillet is 0.2 mm, and an angle between the first ridge surface and the first base surface is in a range of 10° to 40°; The second cam surface, the second base surface and the second light-emitting surface are on the same side of the second lens. There is a rounded corner at the junction of the second cam surface and the second base surface. The radius of the rounded corner is 0.2 mm. The angle between the second cam surface and the second base surface ranges from 10° to 40°.

6. The optical system according to claim 1, wherein: The refractive index range of the optical liquid is (n min -0.2)~(n max +0.2), where n min is the minimum refractive index of the first cantilever surface, n max is the maximum refractive index of the first cantilever surface.

7. A head mounted display device, characterized in that: An optical system comprising any one of claims 1-6.

Images