CN115327776A - Display device and display system - Google Patents

Abstract

The embodiment of the application provides a display device and a display system, and the display device comprises: the lens group and the display screen are sequentially arranged along a first direction; one side of the lens group faces the diaphragm, and the other side of the lens group faces the display screen; the focal length of the lens group is not more than 20 mm; the lens group comprises at least four lenses which are sequentially arranged along a first direction, and each lens is provided with a first optical surface and a second optical surface; the first optical surface and/or the second optical surface of at least one lens is a fresnel surface. The focal length of the lens group in the embodiment of the application is shorter, the field angle is larger, the sense of reality of the image can be reflected, and the image looks more expressive. In addition, under the condition of short focal length, the thickness of the lens can be effectively reduced, so that the whole thickness of the lens group is thinner, the path of light in the lens group is smoother, good imaging quality can be guaranteed, and the user experience can be enhanced.

Description

Display device and display system

Technical Field

The application relates to the technical field of display, in particular to a display device and a display system.

Background

In order to improve user experience, display devices (such as VR (Virtual Reality) devices) are developing in a direction of being light and thin, and the most direct method for reducing the thickness of the display device is to use a short-focus lens scheme. The lens group consisting of 1-3 lenses is adopted as the lens in the related art, which can significantly reduce the thickness of the display device, but the lens group consisting of 1-3 lenses cannot achieve the imaging quality of a large field angle and high definition while achieving a short focal length, and a single lens becomes too thick to bear a large focal power, so that the path of light rays in the lens group is tortuous, and the imaging quality of the display device is poor.

In the related art, the display device further adopts a Pancut type combined lens group, and the whole thickness of the lens group is shortened in a light path folding mode, but the Pancut type combined lens group also has the problems of low light efficiency and ghost which are difficult to solve, and the imaging quality is poor.

Disclosure of Invention

The application aims at the defects of the prior art and provides a display device and a display system, which are used for solving the technical problem that the lens group is too thick or the imaging quality is poor in the prior art.

In a first aspect, an embodiment of the present application provides a display device, including: the lens group and the display screen are sequentially arranged along a first direction; one side of the lens group faces the diaphragm, and the other side of the lens group faces the display screen;

the focal length of the lens group is not more than 20 mm;

the lens group comprises at least four lenses which are sequentially arranged along a first direction, and each lens is provided with a first optical surface and a second optical surface;

the first optical surface and/or the second optical surface of at least one lens is a fresnel surface.

Optionally, the focal length of the lens group is no greater than 17 mm.

Optionally, the focal length of the lens group is not less than

And mm, wherein y is the diagonal length of the display screen, and theta is half of the angle of field of the lens group.

Optionally, the first optical surface of the lens is a light emitting surface, and in the lens group, the first optical surface of the lens closest to the display screen is a fresnel surface.

Optionally, the first optical surface and/or the second optical surface of the plurality of lenses of the lens group other than the fresnel surface is spherical or aspherical.

Optionally, adjacent first and second optical surfaces of at least two adjacent lenses are attached.

Optionally, the thickness of each lens is not more than 8 mm, and the distance between the center of the lens close to the diaphragm in the lens group and the center of the display screen is not more than 25 mm.

Optionally, in the lens group, refractive indexes of adjacent lenses are different, and the refractive index of any lens is not less than 1.5 and not more than 2.

Optionally, the lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence along a first direction;

the first optical surface of the first lens faces the diaphragm, and the second optical surface of the fourth lens is recessed along the first direction and faces the display screen.

Optionally, the lens group further comprises a fifth lens;

the fifth lens is positioned between the first lens and the second lens, and both a first optical surface and a second optical surface of the fifth lens are aspheric surfaces.

Optionally, the lens group further comprises a sixth lens and a seventh lens;

the sixth lens and the seventh lens are sequentially arranged on one side of the first lens, which is far away from the second lens, along the first direction;

the second optical surface of the sixth lens is attached to the first optical surface of the seventh lens, and the second optical surface of the seventh lens is attached to the first optical surface of the first lens.

Optionally, the display screen comprises at least one of a liquid crystal display screen, an organic light emitting semiconductor display screen or a silicon-based liquid crystal display screen, and the diagonal length of the display screen is 0.9 inches to 1.5 inches.

In a second aspect, an embodiment of the present application further provides a display system, including: a diaphragm and any of the display devices as provided in the previous embodiments.

The technical scheme provided by the embodiment of the application brings beneficial technical effects that:

the display device of this application embodiment includes along battery of lens and the display screen that the first direction set gradually, and one side of battery of lens is used for towards the diaphragm, and the opposite side is towards in the display screen, and the emergent light accessible battery of lens of display screen adjusts and propagates to the diaphragm. The focal length of the lens group is shorter, is not more than 20mm, and the field angle is larger, so that the reality of the image can be embodied, and the image can be more expressive. The lens group is provided with at least four lenses, each lens shares the focal power of the lens group uniformly, and the thickness of a single lens is thinner. The lens group comprises at least four lenses which are sequentially arranged along a first direction, each lens is provided with a first optical surface and a second optical surface which are sequentially arranged along the first direction, the first optical surface and/or the second optical surface of at least one lens is a Fresnel surface, and under the condition of short focal length, the thickness of the lens can be effectively reduced, so that the whole thickness of the lens group is thinner, the path of light rays in the lens group is gentler, good imaging quality can be ensured, and the user experience can be enhanced.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a display system according to an embodiment of the present disclosure;

FIG. 2 is a diagram illustrating a modulation transfer function curve of a lens assembly in a display system according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of another display system provided in an embodiment of the present application;

FIG. 4 is a diagram illustrating modulation transfer function curves of a lens group in another display system according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of another display system provided in the embodiment of the present application;

FIG. 6 is a diagram illustrating a modulation transfer function curve of a lens group in another display system according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a display system according to an embodiment of the present application;

FIG. 8 is a diagram illustrating modulation transfer function curves of a lens assembly in a display system according to an embodiment of the present application;

fig. 9 is a schematic structural diagram of another display system provided in an embodiment of the present application;

fig. 10 is a schematic diagram illustrating a modulation transfer function curve of a lens group in a display system according to an embodiment of the present application.

Reference numerals:

100-a display system; 10-a display device; 11-a lens group; 101-a display screen;

110-a first lens; 111 — a first optical surface of the first lens 110; 112-the second optical surface of the first lens 110;

120-a second lens; 121-a first optical surface of the second lens 120; 122-a second optical surface of the second lens 120;

130-a third lens; 131-the first optical surface of the third lens 130; 132 — a second optical surface of the third lens 130;

140-a fourth lens; 141-a first optical surface of the fourth lens 140; 142 a second optical surface of the fourth lens 140;

150-a fifth lens; 151-first optical surface of fifth lens 150; 152-a second optical surface of the fifth lens 150;

160-sixth lens; 161 — a first optical surface of sixth lens 160; 162-a second optical surface of sixth lens 160;

170-seventh lens; 171-a first optical surface of the seventh lens 170; 172-a second optical surface of seventh lens 170;

20-a diaphragm; a-first direction.

Detailed Description

Embodiments of the present application are described below in conjunction with the drawings in the present application. It should be understood that the embodiments set forth below in connection with the drawings are exemplary descriptions for explaining technical solutions of the embodiments of the present application, and do not limit the technical solutions of the embodiments of the present application.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. The term "and/or" as used herein means at least one of the items defined by the term, e.g., "a and/or B" may be implemented as "a", or as "B", or as "a and B".

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

In the related art, in order to obtain good imaging quality, a thicker lens and a larger lens are required to share the optical power of the system, and the whole display device is too heavy. In order to make the display device thinner and lighter, the number of lenses in the lens group is reduced, and the large field angle and the high-definition display of images are difficult to ensure. If adopt pantake formula lens assembly then have the low light efficiency and ghost problem that can't avoid, seriously influence the image quality.

The application provides a display device, aims at solving the above technical problems of the prior art.

The following describes the technical solutions of the present application and how to solve the above technical problems with specific embodiments. It should be noted that the following embodiments may be referred to, referred to or combined with each other, and the description of the same terms, similar features, similar implementation steps and the like in different embodiments is not repeated.

Referring to fig. 1, an embodiment of the present application provides a display device 10, including: the lens group 11 and the display screen 101 are arranged in sequence along the first direction A; the lens assembly 11 has one side facing the stop 20 and the other side facing the display screen 101.

The focal length of the lens group 11 is not more than 20 mm.

The lens group 11 includes at least four lenses arranged in sequence along the first direction a, each lens having a first optical surface and a second optical surface.

The first optical surface and/or the second optical surface of at least one lens is a fresnel surface.

In the present embodiment, the display device 10 includes a lens assembly 11 and a display screen 101 sequentially arranged along the first direction a, one side of the lens assembly 11 is configured to face the stop 20, and the other side of the lens assembly 11 faces the display screen 101, and emergent light of the display screen 101 can be adjusted by the lens assembly 11 and spread to the stop 20. The lens group 11 has a short focal length of not more than 20mm (millimeter) and a large field angle, and can embody the reality of an image, so that the image looks more expressive. The lens group 11 has at least four lenses, each lens shares the focal power of the lens group more uniformly, and the thickness of a single lens is thinner. The lens group 11 comprises at least four lenses which are sequentially arranged along a first direction A, each lens is provided with a first optical surface and a second optical surface which are sequentially arranged along the first direction A, the first optical surface and/or the second optical surface of at least one lens is a Fresnel surface, and under the condition of a short focal length, the thickness of the lens can be effectively reduced, so that the whole thickness of the lens group 11 is thinner, the path of light in the lens group 11 is smoother, good imaging quality can be ensured, and the user experience can be enhanced.

It will be appreciated that in the drawings of the display system provided herein, the various broken lines represent the path of light rays from the display screen 101 through the lens assembly 11 to the stop 20.

Optionally, the focal length of the lens group 11 provided by the present application is short, and can be not greater than 17mm (millimeter), and the focal power of the lens group is uniformly shared by the lenses, so that a single lens is thinner, and the field angle is larger, and meanwhile, the resolution is higher, which may be specifically referred to the data provided by the present application in the following embodiments.

Optionally, the first optical surface and the second optical surface are both planes or curved surfaces substantially perpendicular to the first direction a, the first optical surface is a light exit surface of a lens, the second optical surface is a light entrance surface of a lens, the light entrance surface of each lens faces the display screen 101, the light exit surface faces the diaphragm 20, light is refracted inside the lens or each optical surface for a certain number of times in the lens group 11, and a path is changed, so that a more realistic image is finally viewed through pupils of human eyes.

Alternatively, the optical axes of the lenses in the lens group 11 coincide, the optical axis of the lens group 11 is parallel to the first direction a, and the lens group 11 is arranged coaxially with the display screen 101.

Optionally, the diaphragm 20 comprises a human eye pupil.

In some possible embodiments, the focal length of the lens group 11 is not less than

And mm, wherein y is the diagonal length of the display screen 101, and θ is half of the field angle of the lens group 11.

In the present embodiment, the minimum focal length of the lens group 11 can be determined by the angle of field and the size of the display screen 101. For example, the field angle of the lens group 11 is 60 degrees, the size of the display screen 101 is 0.99 inches, and the minimum focal length thereof may be about 5.1. According to the embodiment of the present disclosure, the number, the focal length or the shape of each lens in the lens assembly 11 can be adjusted according to the focal length required by the lens assembly 11, so as to design the display device 10 that is thinner and has good imaging quality.

In some possible embodiments, the first optical surface is a light emitting surface, and the first optical surface of the lens in the lens group 11 closest to the display screen 101 is a fresnel surface.

In this embodiment, the experiment shows that the optical surface that is close to little display screen 101 sets up to fresnel surface, and light adjusts through fresnel surface sooner promptly, can make 11 images of lens group bright and luminance even to have the fresnel surface of suitable screw thread number through the design, can make 11 frivolous bases of lens group on, it is more clear to image, also possesses good light focus effect.

Optionally, the second optical surface of the lens closest to the display screen 101 and the first optical surface of the lens closest to the human eyes are not provided with a fresnel surface, so that the problem that the surface of the lens is difficult to clean due to the influence of dust, dirt and the like on the fresnel surface and the use experience of a user is influenced can be avoided.

In some possible embodiments, the first optical surface and/or the second optical surface of the plurality of lenses of the lens group 11 other than the fresnel surface is spherical or aspherical.

In this embodiment, the number of aspheric surfaces is greater than that of spherical surfaces, the spherical optical surface may generate slight distortion of the object image in the peripheral field of view range, the optical surface with the aspheric surfaces can correct the coma aberration, astigmatism and other aberrations perpendicular to the optical axis, which affect the imaging quality, so as to improve the imaging quality.

The aspheric surface satisfies the equation

Where Z is the distance from the plane tangent to the surface vertex to the surface, c is the curvature of the aspheric vertex, k is the conic coefficient, r is the height from the optical axis to the surface, A _2i Is a polynomial coefficient.

Moreover, the space occupied by the aspheric surface is smaller than that of the spherical surface to some extent, so that the lens group 11 can be further thinned by adopting a large number of aspheric surface designs.

It is understood that, in the first direction a, the second optical surface of the previous lens is adjacent to the first optical surface of the next lens in the adjacent lenses. Thus, in some possible embodiments, adjacent first and second optical surfaces of at least two adjacent lenses are cemented.

In this embodiment, adjacent optical surfaces of adjacent lenses are attached, so that the distance between the lenses in the lens group 11 can be reduced, and the thickness of the lens group 11 is reduced.

Alternatively, the adjacent optical surfaces of the lens can be bonded by gluing, so that the two optical surfaces are combined into one optical surface, and the lens gluing can use optical glue such as light-cured glue, epoxy glue and the like.

In some possible embodiments, the thickness of each lens is not greater than 8 mm, and the distance between the center of the lens in the lens group 11 near the stop 20 and the center of the display screen 101 is not greater than 25 mm.

In this embodiment, since at least four lenses are used, the system focal power shared by each lens is low, the focal length of each lens can be made smaller, and each lens is thinner and lighter. The total length of the display device 10 is smaller than 25 mm, the single lens can be set to share different focal powers according to the distance from the display screen 101, the thickness of the single lens is designed, the thickness of the single lens does not exceed 8 mm, and compared with the thickness of 1-3 lenses used in the related art, the thickness of the lens group 11 is not too thick on the whole, and the display device 10 can be thinned.

In some possible embodiments, in the lens group 11, refractive indexes of adjacent lenses are different, and the refractive index of any lens is not less than 1.5 and not more than 2.

In this embodiment, the refractive indexes of the adjacent lenses are different, the light propagates through the lenses with different refractive indexes, and the propagation direction of the light generally changes, so that the whole lens group 11 diverges and converges the light of the image of the display screen 101, and a human eye can observe a more high-definition and more realistic image.

Alternatively, the lens may be made of a glass material, and the refractive index of the lens may be 1.73 to 1.96.

Alternatively, the lens may be made of a plastic material, and the refractive index may be 1.51 to 1.66.

In some possible embodiments, the lens group 11 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140, which are sequentially disposed along the first direction a.

The first optical surface 111 of the first lens 110 is configured to face the stop 20, and the second optical surface 142 of the fourth lens 140 is recessed along the first direction a and faces the display screen 101.

In this embodiment, the second optical surface 142 of the fourth lens 140 is a concave surface, or the fourth lens 140 is a convex lens, and the fourth lens 140 converges and diffuses the emergent light of the display screen 101, and the focal length of the fourth lens 140 is the smallest among all the lenses in the lens group 11, and is used for collecting the large-angle light emitted by the display screen 101.

In some embodiments provided by the present application, the contrast ratio at a spatial frequency of 30lp/mm in the modulation transfer function curve of the lens group 11 is not less than 0.35, which has a higher contrast ratio and is more clear in imaging compared to the lens group 11 using 1-3 lenses in the related art.

Optionally, referring to fig. 1, the lens assembly 11 includes four lenses and a display screen 101, a diagonal length of the display screen 101 is 0.99 inch, emergent light of the display screen 101 is diffused in the fourth lens 140 and the third lens 130 in sequence, and is collected in the second lens 120 and the first lens 110, and finally collected to the diaphragm 20. The detailed parameters of the display device 10 are shown in table 1, where f is the focal length, TL is the total length of the lens assembly 11, FOV is the field angle, R is the radius of curvature, T is the center thickness or pitch, and each reference numeral represents the optical surface of each lens.

TABLE 1A PARAMETER TABLE FOR A DISPLAY DEVICE 10

Fig. 2 is a schematic diagram of modulation transfer function curves of different viewing angles of the lens assembly 11 of the display device 10, in which each curve represents a different viewing field position, an abscissa represents a viewing angle, an ordinate represents a contrast, the contrast of each viewing field curve at a position of 30lp/mm (line pair/mm) is not less than 0.5, the resolution of the lens assembly 11 is high, and high-definition display of a full viewing field can be ensured.

In some possible embodiments, the lens group 11 further includes a fifth lens 150.

The fifth lens 150 is located between the first lens 110 and the second lens 120, and both the first optical surface and the second optical surface of the fifth lens 150 are aspheric.

In this embodiment, the lens assembly 11 may include five lenses, and both optical surfaces of the fifth lens 150 are aspheric, so that the whole lens assembly is thin.

Alternatively, referring to fig. 3, the lens assembly 11 includes five lenses and a display screen 101, a diagonal length of the display screen 101 is 0.99 inch, emergent light of the display screen 101 is diffused in the fourth lens 140, the third lens 130 and the second lens 120 in sequence, and is collected in the fifth lens 150 and the first lens 110, and finally is collected to the diaphragm 20. The detailed parameters of the display device 10 are shown in table 2.

Table 2 another parameter table of the display apparatus 10

Fig. 4 is a schematic diagram of modulation transfer function curves of different viewing angles of the lens assembly 11 of the display device 10, in which each curve represents a different viewing field position, an abscissa represents a viewing angle, an ordinate represents a contrast ratio, the contrast ratio of each viewing field curve at a position of 30lp/mm is not less than 0.45, the resolution of the lens assembly 11 is high, and high-definition display of a full viewing field can be ensured.

Alternatively, referring to fig. 5, the lens assembly 11 includes five lenses and a display screen 101, the diagonal length of the display screen 101 is 1.3 inches, the fifth lens 150 is cemented with the second lens 120, and the second optical surface 152 of the fifth lens 150 is cemented with the first optical surface 121 of the second lens 120. The detailed parameters of the display device 10 are shown in table 3.

Table 3 parameter table of another display device 10

Fig. 6 is a schematic diagram of modulation transfer function curves of different field angles of the lens group 11 of the display device 10, in which each curve represents a different field position, an abscissa represents a field angle, and an ordinate represents a contrast ratio, the contrast ratio of each field curve at a position of 30lp/mm is not less than 0.35, the resolution of the lens group 11 is high, and high-definition display in a full field can be ensured.

Alternatively, in another display device 10 provided in the embodiments of the present application, referring to fig. 7, the lens assembly 11 includes five lenses and a display screen 101, and a diagonal length of the display screen 101 is 1.3 inches. The light emitted from the display panel 101 is diffused in the fourth lens 140, the third lens 130, and the second lens 120 in this order, collected by the fifth lens 150 and the first lens 110, and finally collected to the stop 20. The detailed parameters of the display device 10 are shown in table 4.

Table 4 yet another table of parameters for a display device 10

Fig. 8 is a schematic diagram of modulation transfer function curves of different field angles of the lens group 11 of the display device 10, in which each curve represents a different field position, an abscissa represents a field angle, and an ordinate represents a contrast ratio, the contrast ratio of each field curve at a position of 30lp/mm is not less than 0.45, the resolution of the lens group 11 is high, and high-definition display in a full field can be ensured.

In some possible embodiments, the lens group 11 further includes a sixth lens 160 and a seventh lens 170.

The sixth lens 160 and the seventh lens 170 are sequentially disposed on a side of the first lens 110 away from the second lens 120 along the first direction a.

The second optical surface 162 of the sixth lens 160 is bonded to the first optical surface 171 of the seventh lens 170, and the second optical surface 172 of the seventh lens 170 is bonded to the first optical surface 111 of the first lens 110.

In the present embodiment, the lens group 11 includes six lenses, and in order to make the lens group 11 light and thin, adjacent optical surfaces of the sixth lens 160, the seventh lens 170, and the first lens 110, which are adjacent to each other, are bonded.

Optionally, in an embodiment of the present application, there is provided another display device 10, please refer to fig. 9, in which the lens group 11 includes six lenses and one display screen 101, a diagonal length of the display screen 101 is 2.1 inches, and the sixth lens 160, the seventh lens 170 are cemented with the first lens 110. The detailed parameters of the display device 10 are shown in tables 5 and 6.

Table 5 a parameter table of the display apparatus 10

TABLE 6 aspheric coefficient parameter table of display device 10

Fig. 10 is a schematic diagram of modulation transfer function curves of different viewing angles of the lens assembly 11 of the display device 10, in which each curve represents a different viewing field position, an abscissa represents a viewing angle, an ordinate represents a contrast ratio, the contrast ratio of each viewing field curve at 30lp/mm is greater than 0.45, the resolution of the lens assembly 11 is high, and high-definition display of a full viewing field can be ensured.

In some possible embodiments, the display 101 includes at least one of a liquid crystal display 101, an organic light emitting semiconductor display 101, or a silicon-based liquid crystal display 101, and the diagonal length of the display 101 is between 0.9 inches and 3 inches. Specifically, the size of the display screen 101 is related to the total length of the lens group 11, the focal length or other parameters, and the distance from the diaphragm 20 to the lens group 11, and can be designed according to practical situations.

It is understood that the kinds of the display screens 101 are not only the three mentioned above, but also many other kinds, which cannot be mentioned one by one, and those skilled in the art can select different kinds of the display screens 101 according to actual situations.

Based on the same inventive concept, the embodiment of the present application further provides a display system 100, including: an aperture 20 and any of the display devices 10 as provided in the previous embodiments.

The display system 100 provided by the present embodiment includes any one of the display devices 10 provided by the above embodiments, and the implementation principle is similar, which is not described herein again.

Alternatively, the distance from the stop 20 to the closest lens in the lens group 11 is 9 mm to 15 mm.

By applying some embodiments of the present application, at least the following beneficial effects can be achieved:

1. in some embodiments, the display device 10 includes a lens assembly 11 and a display screen 101 sequentially arranged along the first direction a, one side of the lens assembly 11 is configured to face the aperture 20, and the other side faces the display screen 101, and emergent light of the display screen 101 can be adjusted by the lens assembly 11 and transmitted to the aperture 20. The lens group 11 has a short focal length of not more than 20mm (millimeter) and a large field angle, and can embody the reality of an image, so that the image looks more expressive. The lens group 11 has at least four lenses, each lens shares the focal power of the lens group more uniformly, and the thickness of a single lens is thinner. The lens group 11 comprises at least four lenses which are sequentially arranged along the first direction A, each lens is provided with a first optical surface and a second optical surface, the first optical surface and/or the second optical surface of at least one lens is a Fresnel surface, and the thickness of the lens can be effectively reduced under the condition of a short focal length, so that the whole thickness of the lens group 11 is thinner, the path of light rays in the lens group 11 is gentle, good imaging quality can be ensured, and user experience can be enhanced.

2. In some embodiments, the optical surface that is closer to the micro display screen 101 is set as the fresnel surface, i.e. light is adjusted earlier through the fresnel surface, so that the imaging brightness and brightness of the lens set 11 are uniform, and the fresnel surface with a proper number of threads is designed, so that the imaging is clearer on the basis of the lightness and thinness of the lens set 11, and a good light focusing effect is also achieved.

3. In some embodiments, the number of aspheric surfaces is greater than that of spherical surfaces, the spherical optical surface generates a slight distortion of an object image in the peripheral field of view range, the optical surface with the aspheric surfaces can correct coma aberration, astigmatism and other aberrations perpendicular to the optical axis, which affect the imaging quality, so as to improve the imaging quality, and the aspheric optical surface can reduce the use of spherical lenses, so as to improve the transmittance of the virtual reality device, and meanwhile, the aspheric optical surface also has the effect of expanding the field angle.

4. In some embodiments, the adjacent optical surfaces of the adjacent lenses are attached, so that the distance between the lenses in the lens group 11 can be reduced, and the thickness of the lens group 11 is reduced.

5. In some embodiments, since at least four lenses are used, each lens shares a lower system power, the focal length of each lens can be made smaller, and each lens is thinner and lighter. The total length of the display device 10 is smaller than 25 mm, the single lens can be set to different shared focal powers according to the distance from the display screen 101, the thickness of the single lens is designed, the thickness of the single lens does not exceed 8 mm, and compared with the thickness of 1-3 lenses used in the related art, the thickness of the lens group 11 is not too thick on the whole, and the display device 10 can be light and thin.

In the description of the present application, the directions or positional relationships indicated by the words "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like are for convenience of description or simplification based on the exemplary directions or positional relationships shown in the drawings, and do not indicate or imply that the devices or components referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present application.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

The particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is only a part of the embodiments of the present application, and it should be noted that it is within the scope of the embodiments of the present application that other similar implementation means based on the technical idea of the present application can be adopted by those skilled in the art without departing from the technical idea of the present application.

Claims (13)

1. A display device, comprising: the lens group and the display screen are sequentially arranged along a first direction; one side of the lens group faces the diaphragm, and the other side of the lens group faces the display screen;

the focal length of the lens group is not more than 20 mm;

the lens group comprises at least four lenses which are sequentially arranged along the first direction, and each lens is provided with a first optical surface and a second optical surface;

the first optical surface and/or the second optical surface of at least one of the lenses is a fresnel surface.

2. A display device as claimed in claim 1, characterised in that the focal length of the lens group is not more than 17 mm.

3. The display device according to claim 1, wherein a focal length of the lens group is not less than

And mm, wherein y is the diagonal length of the display screen, and theta is half of the field angle of the lens group.

4. The display device according to claim 1, wherein the first optical surface of the lens is a light-emitting surface, and the first optical surface of the lens closest to the display screen in the lens group is a fresnel surface.

5. The display device according to claim 1, wherein the first optical surface and/or the second optical surface of the plurality of lenses of the lens group other than the fresnel surface is spherical or aspherical.

6. The display device according to claim 1, wherein adjacent first and second optical surfaces of at least two adjacent lenses are attached.

7. The display device according to claim 1, wherein each of the lenses has a thickness of not more than 8 mm, and a distance between a center of the lens in the lens group near the stop and a center of the display screen is not more than 25 mm.

8. The display device according to claim 1, wherein refractive indices of adjacent ones of the lenses in the lens group are different, and a refractive index of any one of the lenses is not less than 1.5 and not more than 2.

9. The display device according to claim 1, wherein the lens group includes a first lens, a second lens, a third lens, and a fourth lens arranged in this order in the first direction;

the first optical surface of the first lens is used for facing the diaphragm, and the second optical surface of the fourth lens is concave along the first direction and faces the display screen.

10. The display device according to claim 9, wherein the lens group further comprises a fifth lens;

the fifth lens is located between the first lens and the second lens, and both a first optical surface and a second optical surface of the fifth lens are aspheric surfaces.

11. The display device according to claim 9, wherein the lens group further comprises a sixth lens and a seventh lens;

the sixth lens and the seventh lens are sequentially arranged on one side, away from the second lens, of the first lens along the first direction;

and the second optical surface of the sixth lens is attached to the first optical surface of the seventh lens, and the second optical surface of the seventh lens is attached to the first optical surface of the first lens.

12. The display device according to claim 1, wherein the display screen comprises at least one of a liquid crystal display screen, an organic light emitting semiconductor display screen, or a silicon-based liquid crystal display screen, and a diagonal length of the display screen is 0.9 inches to 1.5 inches.

13. A display system, comprising: a diaphragm and a display device as claimed in any one of claims 1-12.

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