Eyepiece optical system for display equipment and display equipment

Abstract

The invention discloses an eyepiece optical system for display equipment and the display equipment, and the eyepiece optical system comprises a first lens which is located at the light-emitting side of the eyepiece optical system; the second lens is located on the side, away from the light-emitting side, of the first lens. The third lens is located on the side, away from the light-emitting side, of the second lens. The fourth lens is located on the side, away from the light-emitting side, of the third lens. The two opposite surfaces of the first lens and the second lens are the same in surface type, and the two opposite surfaces of the first lens and the second lens are the same in surface type. Thus, the eyepiece optical system with the four lenses is arranged in front of the display screen, an image in a short-distance small display screen is converted into a picture suitable for being observed by human eyes, the number of the lenses in the eyepiece optical system is small, loss of light rays emitted by the display screen when the light rays penetrate through the lenses is reduced, and therefore the lighting effect of the display device is improved, and the user experience is improved. And when the eyepiece optical system is arranged, the assembly difficulty of the eyepiece optical system can be reduced by using fewer lenses.

Description

Technical Field

[0001] The present invention relates to the technical field of optical systems, and in particular to an eyepiece optical system for a display device and a display device. Background Art

[0002] In display devices that require an eyepiece system, such as VR devices, AR devices, and night vision devices, the eyepiece system typically consists of multiple lenses. However, existing eyepiece systems often have a large number of lenses, which results in heavier display devices, reduced light efficiency, and increased assembly difficulty. Furthermore, in wearable devices like VR, this can affect user comfort. Therefore, reducing the number of lenses in the eyepiece optical system has become a pressing technical issue in this field. Summary of the Invention

[0003] An embodiment of the present invention provides an eyepiece optical system for a display device and the display device, so as to reduce the number of lenses in the eyepiece optical system.

[0004] In a first aspect, an embodiment of the present invention provides an eyepiece optical system for a display device, comprising:

[0005] a first lens, located on a light-exiting side of the eyepiece optical system; the light-exiting side being a side of the eyepiece optical system away from the display screen in the display device;

[0006] a second lens, located on a side of the first lens away from the light-emitting side;

[0007] a third lens, located on a side of the second lens away from the light-emitting side;

[0008] a fourth lens, located on a side of the third lens away from the light-emitting side;

[0009] The optical axes of the first lens, the second lens, the third lens and the fourth lens coincide with each other; the two surfaces facing each other of the first lens and the second lens have the same surface shape; and the two surfaces facing away from each other of the first lens and the second lens have the same surface shape.

[0010] In a second aspect, an embodiment of the present invention provides a display device, comprising: a display screen, and the eyepiece optical system as described in the first aspect above, wherein the display screen and the eyepiece optical system are arranged in a one-to-one correspondence.

[0011] The beneficial effects of the present invention are as follows:

[0012] An embodiment of the present invention provides an eyepiece optical system for a display device and a display device, comprising: a first lens located on a light-exiting side of the eyepiece optical system; the light-exiting side being the side of the eyepiece optical system facing away from a display screen in the display device; a second lens located on a side of the first lens facing away from the light-exiting side; a third lens located on a side of the second lens facing away from the light-exiting side; and a fourth lens located on a side of the third lens facing away from the light-exiting side; the optical axes of the first lens, the second lens, the third lens, and the fourth lens coincide; the two surfaces facing each other of the first lens and the second lens have the same surface shape, i.e., the first surface and the second surface have the same surface shape; and the two surfaces facing each other of the first lens and the second lens have the same surface shape, i.e., the third surface and the fourth surface have the same surface shape. Thus, by setting the surface shapes of the first surface and the second surface to be the same, and the surface shapes of the third surface and the fourth surface to be the same, a symmetrical arrangement of the first lens and the second lens is achieved, thereby achieving aberration balance through geometric symmetry without the need for complex algorithms or additional components, thereby improving the display effect of the display device. In addition, the symmetrical arrangement of the first lens and the second lens can reduce the sensitivity of assembly errors of the eyepiece optical system to the optical axis, thereby improving the fault tolerance of the production process. In addition, by setting an eyepiece optical system with four lenses in front of the display screen, the image in a small display screen at a close distance is converted into a picture suitable for observation by the human eye. The number of lenses in the eyepiece optical system is relatively small, which reduces the loss of light emitted by the display screen when passing through each lens, thereby improving the light efficiency of the display device and reducing the energy consumption of the display device. When setting the eyepiece optical system, fewer lenses can also reduce the difficulty of assembling the eyepiece optical system. When the display device is a wearable display device such as VR or AR, fewer eyepieces in the eyepiece optical system can reduce the weight of the display device, thereby improving the wearing comfort of the display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the structure of a first eyepiece optical system provided in an embodiment of the present invention;

[0014] Figure 2 Schematic diagram of the structure of a second eyepiece optical system provided in an embodiment of the present invention;

[0015] Figure 3 Schematic diagram of the structure of a third eyepiece optical system provided in an embodiment of the present invention;

[0016] Figure 4 Schematic diagram of the structure of a fourth eyepiece optical system provided in an embodiment of the present invention;

[0017] Figure 5 This is an MTF variation curve of an eyepiece optical system provided in an embodiment of the present invention within a spatial frequency of 10 lp / mm;

[0018] Figure 6This is an MTF variation curve of an eyepiece optical system provided in an embodiment of the present invention within a spatial frequency of 30 lp / mm;

[0019] Figure 7 The figure is a schematic structural diagram of a display device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following, in conjunction with the accompanying drawings, describes in detail the specific implementations of an eyepiece optical system for a display device and a display device provided by an embodiment of the present invention. It should be noted that the described embodiments are only some of the embodiments of the present invention, and not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] An embodiment of the present invention provides an eyepiece optical system for a display device, such as Figure 1 As shown, including:

[0022] The first lens 101 is located on the light-emitting side of the eyepiece optical system 100; the light-emitting side is the side of the eyepiece optical system 100 away from the display screen 200 in the display device, that is, Figure 1 the left side of the middle;

[0023] The second lens 102 is located on a side of the first lens 101 away from the light-emitting side;

[0024] The third lens 103 is located on the side of the second lens 102 away from the light-emitting side;

[0025] The fourth lens 104 is located on a side of the third lens 103 away from the light-emitting side;

[0026] The optical axes of the first lens 101, the second lens 102, the third lens 103, and the fourth lens 104 coincide with each other. The two surfaces of the first lens 101 and the second lens 102 facing each other have the same surface shape, that is, the first surface M1 and the second surface M2 have the same surface shape. The two surfaces of the first lens 101 and the second lens 102 facing each other have the same surface shape, that is, the third surface M3 and the fourth surface M4 have the same surface shape.

[0027] In this way, by setting the surface shapes of the first surface and the second surface to be the same, and the surface shapes of the third surface and the fourth surface to be the same, a symmetrical setting of the first lens and the second lens is achieved, thereby eliminating the need for complex algorithms or additional components, and achieving aberration balance through geometric symmetry, thereby improving the display effect of the display device. The symmetrical setting of the first lens and the second lens can also reduce the sensitivity of the assembly error of the eyepiece optical system to the optical axis, thereby improving the fault tolerance of the production process. In addition, by setting an eyepiece optical system with four lenses in front of the display screen, the image on a small display screen at a close distance is converted into a picture suitable for human eye observation. The eyepiece optical system has a small number of lenses, which reduces the loss of light emitted by the display screen when passing through each lens, thereby improving the light efficiency of the display device and reducing the energy consumption of the display device. When setting the eyepiece optical system, fewer lenses can also reduce the difficulty of assembling the eyepiece optical system. When the display device is a wearable display device such as VR or AR, fewer eyepieces in the eyepiece optical system can reduce the weight of the display device, thereby improving the wearing comfort of the display device.

[0028] Among them, when the surface shapes of the first surface M1, the second surface M2, the third surface M3 and the fourth surface M4 are spherical, the same surface shape can be understood as the same curvature radius; when the surface shapes of the first surface M1, the second surface M2, the third surface M3 and the fourth surface M4 are aspherical, the same surface shape can be understood as the same high-order terms. The surface shapes of the third lens 103 and the fourth lens 104 in the eyepiece optical system 100 can be surface shapes well known to those skilled in the art and are not specifically limited here.

[0029] Of course, in a specific implementation, the surface shapes of the two surfaces of the first lens and the second lens facing each other can be set to be similar, and accordingly, the curvature radius or high-order terms of the two surfaces of the first lens and the second lens facing each other are similar. The surface shapes of the two surfaces of the first lens and the second lens facing each other can also be set to be similar, and accordingly, the curvature radius or high-order terms of the two surfaces of the first lens and the second lens facing each other are similar, thereby reducing the aberration of the eyepiece optical system while reducing the difficulty of manufacturing the lenses in the eyepiece optical system, thereby reducing the cost of the display device.

[0030] It should be understood that when using some display devices, the display screen is close to the human eye, such as VR, AR and other display devices, the display screen is only a few centimeters away from the human eye, but the human eye cannot directly focus on such close objects, so this type of display device is provided with an eyepiece optical system. In a display device with an eyepiece optical system, the eyepiece optical system is located between the display screen and the human eye. The eyepiece optical system magnifies the screen image through each lens and adjusts the light path so that the virtual picture is visually equivalent to a distant object, so that the human eye can focus on the picture on the display screen, achieve clear display, and reduce eye fatigue.

[0031] Further, if Figure 1 As shown, the optical length L1 of the eyepiece optical system 100 is less than 35 mm. The optical length L1 is the distance between the surface of the first lens 101 facing away from the display screen 200 and the display screen 200. Thus, the eyepiece optical system 100, which is composed of four lenses, has a shorter optical length, thereby reducing the size of the display device and improving its portability.

[0032] In the eyepiece optical system, as the FOV (Field of View) increases, the imaging of the eyepiece optical system will show increasingly serious off-axis aberrations, such as astigmatism, field curvature, distortion, and chromatic aberration of magnification. Simple spherical lenses cannot effectively correct these aberrations within a limited space. Therefore, it is necessary to adopt an aspheric surface, or increase the number of lenses, or both adopt an aspheric surface and increase the number of lenses.

[0033] Optionally, the surfaces of the first lens, the second lens, the third lens, and the fourth lens are even-aspherical or Q-type. By configuring the surfaces of each lens in the eyepiece optical system as even-aspherical or Q-type, spherical aberration of the eyepiece optical system can be reduced, thereby improving the imaging quality of the display device.

[0034] Of course, the surface shapes of the first lens, the second lens, the third lens and the fourth lens may also be other rotationally symmetric surface shapes well known to those skilled in the art, such as Zernike polynomial surface shapes, which are not specifically limited here.

[0035] In addition, when the lens in the eyepiece optical system is a spherical lens, since the spherical lens requires a combination of multiple lenses to correct aberrations, the number of lenses in the eyepiece optical system will be large, and thus the optical length will be long. Therefore, when the surface shapes of the first lens, the second lens, the third lens and the fourth lens adopt rotationally symmetrical surface shapes such as even aspherical surfaces or Q-type surfaces, since a single aspherical lens can achieve the aberration correction effect of multiple spherical lenses, the number of lenses in the eyepiece optical system can be reduced, the optical length of the eyepiece optical system can be effectively shortened, and the volume of the display device can be reduced.

[0036] Furthermore, when the electronic device is a VR, AR or other device, the curvature and aspheric coefficient of the edge area of ​​the surface of the first lens facing away from the display screen can be adjusted so that the light deflection in the edge area of ​​the surface of the first lens facing away from the display screen is smoother, thereby avoiding the light angle being too large and causing the light to be unable to enter the pupil. It should be understood that when the electronic device is a VR, AR or other device, the design of the eyepiece optical system needs to take into account the characteristics of the human eye, such as the dynamic displacement of the pupil position: the center of the pupil moves within the range of 6mm to 8mm when the human eyeball moves, and the pupil size changes: the diameter of the human pupil is about 2mm in a bright environment and can reach 6mm to 8mm in a dark environment. Therefore, by reducing the curvature of the edge area of ​​the surface of the first lens facing away from the display screen, the eyepiece optical system can ensure that the light at the edge of the field of view accurately enters the pupil at all pupil positions, thereby avoiding the light at the edge of the field of view being blocked or the increase of stray light due to pupil contraction, expansion, and movement, thereby avoiding retinal imaging distortion and dispersion, and improving the display effect of the display device.

[0037] Alternatively, as Figure 2 As shown, the surface of the first lens 101 facing the light-emitting side is a plane, that is, the first surface M3 is a plane. As the first lens 101 is on the side of the display device closest to the human eye, setting the third surface M3 as a plane can increase the distance between the human eye and the third surface M3, thereby preventing eyelashes from contacting the lens and providing a more comfortable wearing space. Furthermore, as the third surface M3 is the side that can be directly observed by the user, setting the third surface M3 as a plane can improve the aesthetics of the display device.

[0038] Optionally, the first lens has a first focal length, the second lens has a second focal length, the third lens has a third focal length, and the fourth lens has a fourth focal length, wherein the first focal length, the second focal length, and the third focal length are greater than zero, and the fourth focal length is less than zero. The parameters of each lens in the eyepiece optical system can also be expressed by optical power, which is the reciprocal of the focal length. Therefore, the optical power of the first lens, the second lens, and the third lens are all greater than zero, and the optical power of the fourth lens is less than zero.

[0039] In this way, by limiting the focal length of each lens in the eyepiece optical system, an eyepiece optical system comprising four lenses can be used to project the image on the display screen to the human eye, thereby realizing the display of the display device, improving the light efficiency of the display device, reducing the energy consumption of the display device, and reducing the difficulty of assembling the eyepiece optical system.

[0040] Alternatively, as Figure 1As shown, the first lens 101, the second lens 102, and the third lens 103 are biconvex lenses, and the fourth lens 104 is a biconcave lens. Thus, through the specific arrangement of the concave and convex lenses, the eyepiece optical system 100, consisting of four lenses, can project the image on the display screen 200 to the human eye. This enables the display device to display images using a smaller number of lenses, thereby reducing the energy consumption of the display device, simplifying the assembly of the eyepiece optical system, and reducing the weight of the display device.

[0041] Optionally, the eyepiece optical system has a system focal length, a ratio of the first focal length to the system focal length is greater than 1 and less than 2, a ratio of the second focal length to the system focal length is greater than 1 and less than 2, a ratio of the third focal length to the system focal length is greater than 1 and less than 2, a ratio of the first focal length to the fourth focal length is greater than -1 and less than -0.4, a ratio of the second focal length to the first focal length is greater than 0.9 and less than 1, and a ratio of the third focal length to the first focal length is greater than 0.9 and less than 1. In this way, by setting the ratio of the focal lengths of the lenses in the eyepiece optical system, the focal length relationship of the lenses is defined, so that the eyepiece optical system can project the image on the display screen to the human eye, thereby realizing display on the display device.

[0042] Furthermore, the ratio of the sum of the first focal length, the second focal length, the third focal length, and the fourth focal length to the system focal length is greater than 1 and less than 2. In this way, since the FOV of the eyepiece optical system is roughly the ratio of the display screen size to the system focal length, by further limiting the system focal length, the FOV of the eyepiece optical system can be controlled, thereby achieving a desired FOV.

[0043] Optionally, when the first lens has a first focal length, the second lens has a second focal length, the third lens has a third focal length, and the fourth lens has a fourth focal length, and the first focal length and the second focal length are greater than zero, the third focal length can be set to be less than zero. At this time, the fourth focal length can be set to be greater than zero or less than zero, that is, the optical focal power of the first lens and the second lens is greater than zero, the optical focal power of the third lens is less than zero, and the optical focal power of the fourth lens is greater than zero or less than zero.

[0044] In this way, by adopting different focal length combinations, the eyepiece optical system is also composed of four lenses, which improves the design flexibility of the eyepiece optical system, improves the light efficiency of the display device, reduces the energy consumption of the display device, and reduces the difficulty of assembling the eyepiece optical system.

[0045] When the third focal length is less than zero and the fourth focal length is greater than zero or less than zero, the shapes of the third lens and the fourth lens can be as follows: Figure 3 or Figure 4 As shown, the third lens 103 is a biconcave lens ( Figure 3 ) or meniscus lens ( Figure 4), and the fourth lens 104 is a meniscus lens. When the third lens 103 is a meniscus lens, the side of the third lens 103 facing the eye is nearly flat, and thus its shape resembles a plano-concave lens. This allows the eyepiece optical system to employ a variety of lens configurations, further enhancing its design flexibility.

[0046] In addition, the eyepiece optical system has a system focal length, an absolute value of a ratio of the third focal length to the system focal length is greater than 0.8 and less than 2, an absolute value of a ratio of the fourth focal length to the first focal length is greater than 2 and less than 7, and a ratio of the third focal length to the first focal length is greater than -1.5 and less than -0.8. Since the fourth focal length may be greater than or less than zero, values ​​associated with the fourth focal length are described using absolute values.

[0047] Furthermore, an absolute value of a ratio of a sum of the first focal length, the second focal length, the third focal length, and the fourth focal length to the system focal length is greater than 1 and less than 2.

[0048] In this way, when the third focal length is less than zero and the fourth focal length is greater than zero or less than zero, the focal length of each lens in the eyepiece optical system is also limited by setting the ratio of the focal lengths of each lens, so that the eyepiece optical system can project the image in the display screen to the human eye, realize the display of the display device, and can control the FOV of the eyepiece optical system to achieve the required FOV.

[0049] Optionally, the refractive index of the first lens, the second lens, the third lens, and the fourth lens is greater than 1.5 and less than 1.8. In this way, by adjusting the refractive index of each lens in the eyepiece optical system, excessive chromatic aberration and reflection loss caused by excessively large refractive index are avoided, thereby improving the display effect of the display device. Furthermore, an increase in lens thickness caused by excessively small refractive index is avoided, thereby reducing the weight of the eyepiece optical system.

[0050] Optionally, the Abbe number of the first lens and the second lens is greater than 40 and less than 60; the Abbe number of the third lens is greater than 40 and less than 60, and the Abbe number of the fourth lens is greater than 18 and less than 40; or the Abbe number of the third lens is greater than 18 and less than 40, and the Abbe number of the fourth lens is greater than 40 and less than 60. The Abbe number indicates the degree of change in the refractive index of a material for light of different wavelengths. The higher the Abbe number, the smaller the dispersion and the milder the chromatic aberration of the material. Generally, materials with higher Abbe numbers have lower refractive indices.

[0051] By setting the Abbe number of each lens within a certain range, we can avoid excessive dispersion caused by a too-small Abbe number, thereby improving the display quality of the display device. We can also avoid the low refractive index of the material caused by a too-large Abbe number, which in turn leads to thicker lenses, thereby reducing the weight of the display device and improving its portability. Furthermore, the coordinated Abbe numbers of the third and fourth lenses can further eliminate residual chromatic aberration, further improving the display quality of the display device.

[0052] Furthermore, when the display device is a wearable display device such as VR or AR, the lens in the eyepiece optical system can be made of high-refractive-index material, and the lens surface can be an aspheric surface, thereby reducing the thickness of the lens and the number of lenses. While achieving aberration correction of the eyepiece optical system, the weight and length of the eyepiece optical system are reduced, thereby improving the comfort of use of the display device.

[0053] In addition, the material used to make each lens in the eyepiece optical system can be glass. When glass is used as the material for the lens, higher light transmittance and lower dispersion can be achieved. Glass has a wide range of refractive indexes and is easy to select. Glass also has properties such as high temperature resistance, scratch resistance, and non-deformation resistance, making it suitable for various special environments and improving the reliability of the display device. Alternatively, the material used to make each lens in the eyepiece optical system can be plastic. When plastic is used as the material for the lens, the weight of the eyepiece optical system can be effectively reduced. For example, when all four lenses are made of plastic, the total weight can be less than 15g. Therefore, when the eyepiece optical system is applied to a wearable display device, the user's comfort can be improved. Plastic also has the advantages of impact resistance, low cost, and flexible design, which can improve the safety of the display device and reduce the cost of the display device.

[0054] Furthermore, the first and second lenses can be configured as Fresnel lenses, or the opposing surfaces of the first and second lenses can be configured as Fresnel lenses, thereby reducing the thickness of the first and second lenses, further reducing the optical length and weight of the eyepiece optical system. For example, when all four lenses are made of plastic, the total weight of the eyepiece optical system can be less than 10g, and the optical length can be less than 29mm.

[0055] Of course, the materials used to make each lens in the eyepiece optical system can be set to different. For example, the material used to make the first lens can be set to plastic, and the materials used to make the second lens, the third lens, and the fourth lens can be set to glass. This can achieve higher light transmittance and lower dispersion for the eyepiece optical system while reducing the risk of damage to the user caused by the first lens and improving the safety of the display device. The materials used to make each lens in the eyepiece optical system are not specifically limited here.

[0056] Optionally, at least one side of at least some of the first, second, third, and fourth lenses is provided with an anti-reflection film. When providing the anti-reflection film, since the reflection loss at the light incident surface of the lens is greater, an anti-reflection film can be provided on the light incident surface of each lens. The light incident surface can be understood as the surface facing the display screen. Alternatively, an anti-reflection film can be provided on the light incident surface of some lenses to reduce the process complexity of the eyepiece optical system. Alternatively, an anti-reflection film can be provided on both sides of each lens to minimize the loss of light and reduce the energy consumption of the display device. The specific arrangement of the anti-reflection film is not limited here. In this way, by providing the anti-reflection film in the eyepiece optical system, the reflection of light incident from the display screen to the eyepiece optical system is reduced, the light efficiency of the display device is improved, and thus the power consumption of the display device is reduced.

[0057] Alternatively, as Figure 2 As shown, a distance d1 between the center of the surface of the fourth lens 104 facing the display screen 200 and the display screen 200 along the optical axis L is greater than 5 mm, and a distance d2 between the edge of the surface of the fourth lens 104 facing the display screen 200 and the display screen 200 along the optical axis L is greater than 2.5 mm.

[0058] In this way, by setting a certain distance between the eyepiece optical system and the display screen, there is sufficient space between the eyepiece optical system and the display screen. When the eyepiece optical system and the display screen are assembled, the eyepiece optical system can move within the sufficient space, thereby achieving clear imaging of the display device.

[0059] Alternatively, as Figure 1 As shown, the exit pupil distance L2 is greater than 15 mm. The exit pupil distance L2 is the distance between the human eye E and the surface of the first lens 101 facing the human eye when the display device is in use. By setting a certain length for the exit pupil distance L2, it is possible to avoid a situation where a user's glasses are not able to fit properly due to a too small exit pupil distance L2. This allows users who wear glasses to use the display device with an eyepiece optical system, thereby improving the practicality of the display device.

[0060] In addition, the eye movement range of the eyepiece optical system can be set to be greater than 8 mm, thereby ensuring that the user can always receive the image of the display screen when the through-hole moves, thereby improving the practicality of the display device.

[0061] The following describes the implementation effects of the eyepiece optical system provided by the embodiments of the present invention in conjunction with specific embodiments.

[0062] like Figure 5 As shown, Figure 5This is the MTF (Modulation Transfer Function) curve of the eyepiece optical system within a spatial frequency of 10lp / mm. MTF quantifies the resolution of the eyepiece optical system by the degree of contrast attenuation. Its value range is 0 to 1. The higher the value, the stronger the ability of the eyepiece optical system to retain details. Figure 5 The different curves in the figure represent the MTF variation curves under different field of view angles. Figure 5 As can be seen in the figure, when the spatial frequency increases to 10lp / mm, the maximum MTF only drops by 0.1, maintaining a high MTF value, thereby achieving a higher resolution of the eyepiece optical system and improving the display effect of the display device.

[0063] like Figure 6 As shown, Figure 6 This is the MTF variation curve of the eyepiece optical system within the spatial frequency of 30lp / mm. Figure 6 The different curves in the figure also represent the MTF change curves under different field angles. Figure 5 ,from Figure 6 It can be seen that when the spatial frequency continues to increase to 30lp / mm, the MTF does not fall below 0.5, and still maintains a relatively high MTF value. This further illustrates that the eyepiece optical system provided by the embodiment of the present invention can achieve a higher resolution and improve the display effect of the display device.

[0064] In addition, in a specific embodiment, the FOV of the eyepiece optical system can be greater than 63°, and the overall transmittance of the eyepiece optical system can be greater than 70%. After setting an anti-reflection film, the overall transmittance of the eyepiece optical system can be further increased to more than 80%, thereby achieving high-quality imaging while reducing the power consumption of the display device.

[0065] Based on the same inventive concept, an embodiment of the present invention further provides a display device. The implementation principle of the display device is similar to that of the aforementioned eyepiece optical system. The specific implementation method of the display device can be found in the embodiment of the aforementioned eyepiece optical system, and the repeated parts will not be repeated.

[0066] Specifically, an embodiment of the present invention provides a display device, such as Figure 7 As shown, it includes: a display screen 200 and the eyepiece optical system 100 as described above, and the display screen 200 is arranged in a one-to-one correspondence with the eyepiece optical system 100. Among them, the display device includes but is not limited to: VR equipment, AR equipment, night vision equipment, etc., and the number of eyepiece optical systems 100 in the display device includes but is not limited to 1, 2, 3 or more.

[0067] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An eyepiece optical system for a display device, characterized in that: include: a first lens, located on the light exit side of the eyepiece optical system; The light exit side is the side of the eyepiece optical system facing away from the display screen in the display device; a second lens, located on a side of the first lens away from the light-emitting side; a third lens, located on a side of the second lens away from the light-emitting side; a fourth lens, located on a side of the third lens away from the light-emitting side; The optical axes of the first lens, the second lens, the third lens and the fourth lens coincide with each other; the two surfaces facing each other of the first lens and the second lens have the same surface shape; and the two surfaces facing away from each other of the first lens and the second lens have the same surface shape.

2. The eyepiece optical system according to claim 1, wherein: The surface shapes of the first lens, the second lens, the third lens and the fourth lens are even aspherical or Q-type surfaces.

3. The eyepiece optical system according to claim 1, wherein: The surface of the first lens facing the light-emitting side is a plane.

4. The eyepiece optical system according to any one of claims 1 to 3, wherein: The first lens has a first focal length, the second lens has a second focal length, the third lens has a third focal length, and the fourth lens has a fourth focal length. The first focal length, the second focal length, and the third focal length are greater than zero, and the fourth focal length is less than zero.

5. The eyepiece optical system according to claim 4, wherein: The third lens is a biconvex lens, and the fourth lens is a biconcave lens.

6. The eyepiece optical system according to claim 4, wherein: The eyepiece optical system has a system focal length, a ratio of the first focal length to the system focal length is greater than 1 and less than 2, a ratio of the second focal length to the system focal length is greater than 1 and less than 2, a ratio of the third focal length to the system focal length is greater than 1 and less than 2, a ratio of the first focal length to the fourth focal length is greater than -1 and less than -0.4, a ratio of the second focal length to the first focal length is greater than 0.9 and less than 1, and a ratio of the third focal length to the first focal length is greater than 0.9 and less than 1.

7. The eyepiece optical system according to claim 6, wherein: A ratio of the sum of the first focal length, the second focal length, the third focal length, and the fourth focal length to the system focal length is greater than 1 and less than 2.

8. The eyepiece optical system according to any one of claims 1 to 3, wherein: The first lens has a first focal length, the second lens has a second focal length, the third lens has a third focal length, and the fourth lens has a fourth focal length. The first focal length and the second focal length are greater than zero, the third focal length is less than zero, and the fourth focal length is greater than zero or less than zero.

9. The eyepiece optical system according to claim 8, wherein: The third lens is a biconcave lens or a meniscus lens, and the fourth lens is a meniscus lens.

10. The eyepiece optical system according to claim 8, wherein: The eyepiece optical system has a system focal length, the absolute value of the ratio of the third focal length to the system focal length is greater than 0.8 and less than 2, the absolute value of the ratio of the fourth focal length to the first focal length is greater than 2 and less than 7, and the ratio of the third focal length to the first focal length is greater than -1.5 and less than -0.

8.

11. The eyepiece optical system according to claim 10, wherein: An absolute value of a ratio of a sum of the first focal length, the second focal length, the third focal length, and the fourth focal length to the system focal length is greater than 1 and less than 2.

12. The eyepiece optical system according to claim 1, wherein: The refractive indexes of the first lens, the second lens, the third lens, and the fourth lens are greater than 1.5 and less than 1.

8.

13. The eyepiece optical system according to claim 1, wherein: The Abbe numbers of the first lens and the second lens are greater than 40 and less than 60; The Abbe number of the third lens is greater than 40 and less than 60, and the Abbe number of the fourth lens is greater than 18 and less than 40, or the Abbe number of the third lens is greater than 18 and less than 40, and the Abbe number of the fourth lens is greater than 40 and less than 60.

14. The eyepiece optical system according to claim 1, wherein: At least one side of at least some of the first lens, the second lens, the third lens, and the fourth lens is provided with an antireflection film.

15. The eyepiece optical system according to claim 1, wherein: The distance between the center of the surface of the fourth lens facing the display screen and the display screen along the optical axis is greater than 5 mm, and the distance between the edge of the surface of the fourth lens facing the display screen and the display screen along the optical axis is greater than 2.5 mm.

16. A display device, characterized in that: include: A display screen, an eyepiece optical system according to any one of claims 1 to 15, wherein the display screen is arranged in a one-to-one correspondence with the eyepiece optical system.

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