Light and thin near-eye display apparatus capable of eliminating stray light

Abstract

A light and thin near-eye display apparatus capable of eliminating stray light, comprising: an imaging prism unit (2), which comprises a first prism having a first optical surface, a second optical surface and a third optical surface, and a film system unit, the film system unit being located between the first prism and a second prism (3); a display chip (1), which is arranged close to the third optical surface and is used for providing imaging light; the second prism (3), which is a Fresnel prism and is arranged close to the second optical surface, a Fresnel surface of the second prism (3) being reasonably configured; and an imaging lens unit (4), which is arranged close to the first optical surface, a first semi-transparent semi-reflective film being arranged on the side of the imaging lens unit facing away from the imaging prism unit (2). The imaging light emitted by the display chip (1) enters the imaging prism unit (2), is reflected by the film system unit to the imaging lens unit (4), is then reflected back to the imaging prism unit (2) by the first semi-transparent semi-reflective film, and sequentially passes through the second prism (3) and a diaphragm to be incident to human eyes. The device can eliminate stray light to improve the display effect, and achieves overall lightening and thinning, thereby improving the user comfort and experience and aesthetics.

Description

A thin and light near-eye display device capable of eliminating stray light

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 16, 2023, with application number 202311529739.7, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application belongs to the field of near-eye display technology, and specifically relates to a thin and lightweight near-eye display device capable of eliminating stray light. Background Art

[0004] In augmented reality (AR) products, weight, thickness and good display effects are important manifestations of product strength. Therefore, in the process of making products lighter and thinner, improving the display effect of products is a problem that AR products must overcome. The optical solutions currently on the market are based on the transmission of light emitted by the image through a total reflection prism, and are combined with a refractive lens to achieve near-eye display. For example, it includes an image source, a first prism, a second prism, and a first lens. The projection light output by the image source is incident on the first prism, and after multiple reflections, it is incident on the first lens. After being reflected by the first lens, it passes through the first prism and the second prism in turn to enter the human eye. The problem with this solution is that the use of multiple prisms makes it heavier and thicker, which is still a gap from the thinness and lightness pursued by AR glasses, and it is easy to introduce stray light into the screen, affecting the display effect.

[0005] Summary of the Invention

[0006] The purpose of this application is to address the above-mentioned problems and propose a thin and lightweight near-eye display device that can eliminate stray light, optimize stray light, improve display effects, and achieve overall thinness, thereby improving user comfort, experience and aesthetics.

[0007] To achieve the above objectives, the technical solutions adopted in this application are:

[0008] The present application proposes a thin and lightweight near-eye display device capable of eliminating stray light, comprising a display chip, an imaging prism unit, a second prism, an imaging lens unit, and an aperture, wherein:

[0009] An imaging prism unit includes a first prism and a film system unit, wherein the first prism has a first optical surface, a second optical surface, and a third optical surface, and the film system unit is located between the first prism and the second prism;

[0010] A display chip is disposed adjacent to the third optical surface of the first prism and is used to provide imaging light;

[0011] The second prism is a Fresnel prism and is disposed adjacent to the second optical surface of the first prism. The Fresnel surface of the second prism faces the human eye and meets the following conditions:

[0012] sin(β)*n>sin(max(aor)) or sin(β)*n <sin(min(aor));

[0013] r / pitch < 0.05;

[0014] R / pitch < 0.05;

[0015] Wherein, β represents the draft angle of each tooth, aor represents the angle range between the tooth top and tooth bottom of each tooth draft angle and the line connecting any point of the aperture and the normal line of the aperture, max(aor) represents the maximum value of aor, min(aor) represents the minimum value of aor, n represents the refractive index of the material of the Fresnel prism, pitch represents the tooth width of each tooth, r represents the chamfer radius of the tooth bottom of each tooth, and R represents the chamfer radius of the tooth tip of each tooth;

[0016] An imaging lens unit is disposed close to the first optical surface of the first prism, and a first semi-transparent and semi-reflective film is disposed on a side facing away from the imaging prism unit;

[0017] The imaging light emitted by the display chip enters the imaging prism unit, is reflected by the film system unit to the imaging lens unit, and then is reflected back to the imaging prism unit by the first semi-transparent and semi-reflective film and sequentially passes through the second prism and the aperture to enter the human eye.

[0018] Preferably, the pitch value of the Fresnel surface of the second prism is in the range of 0.15 mm to 0.6 mm, and the value ranges of r and R are both in the range of 0.005 mm to 0.02 mm.

[0019] Preferably, the film system unit includes at least one of a second semi-transmissive and semi-reflective film, a reflective polarizing film, a quarter-wave plate and an absorbing polarizing film.

[0020] Preferably, the included angle between the first optical surface and the second optical surface of the first prism is 15° to 35°.

[0021] Preferably, the air gap between the imaging prism unit and the imaging lens unit is 0.01 mm to 1.0 mm.

[0022] Preferably, the imaging lens unit is a curved lens, and the curvature radius R11 of the mirror surface close to the first prism satisfies R11≥150mm or R11≤-150mm, the curvature radius R12 of the mirror surface away from the first prism satisfies 40mm≤R12≤75mm, and the curvature radius R13 of the third optical surface of the first prism satisfies R13≥22mm or R13≤-100mm.

[0023] Preferably, the refractive index of the first prism and the second prism are both 1.45-1.75, and the Abbe number of the first prism and the second prism are both 18.0-60.0.

[0024] Preferably, the thin and light near-eye display device capable of eliminating stray light further comprises a compensation lens unit, which is arranged close to the first semi-transmissive and semi-reflective film, and the focal length of the compensation lens unit is opposite to the focal length of the imaging lens unit.

[0025] Preferably, the focal length of the imaging lens unit is 10 mm to 25 mm.

[0026] Preferably, the display chip moves relative to the imaging prism unit to perform diopter adjustment.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1) The near-eye display device includes a display chip, an imaging prism unit, a second prism, an imaging lens unit, and an aperture. The second prism adopts a Fresnel prism. By adjusting the draft angle β, pitch, r, and R values ​​of each tooth on the Fresnel prism, the generated total reflection stray light is adjusted outside the field of view to reduce smear and reduce the risk of stray light, thereby achieving the purpose of optimizing stray light for the near-eye display device. Moreover, by adopting the Fresnel prism, compared with the conventional technology using ordinary prisms, the overall weight can be further reduced while ensuring the imaging light path and improving the display effect. The bottom of the device can also be made thinner. Based on the prism total reflection architecture, the imaging light emitted by the display chip is incident on the imaging prism unit and then reflects multiple times to achieve light path folding. On the basis of ensuring sufficient optical path of the imaging light, the imaging prism unit is avoided from being too large, thereby avoiding the problem of increasing the overall volume of the near-eye display device. This is conducive to further achieving overall lightweight and thinness, and improving user comfort, experience, and aesthetics.

[0029] 2) Aberration correction is performed through a compensating lens unit, whose focal length is opposite to that of the imaging lens unit, to correct the aberration generated by the human eye when viewing the outside world through the imaging lens unit, ensuring that the aberration of the outside world seen by the human eye is sufficiently small, further improving user comfort;

[0030] 3) By changing the distance between the display chip and the first prism, the imaging position of the imaging light can be changed to achieve diopter adjustment, thereby adapting to wearers with different myopia degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a light path diagram of the near-eye display device of the present application.

[0032] FIG2 is a diagram showing the optical path of the main light beam of the near-eye display device of the present application.

[0033] FIG3 is a partial enlarged view of portion A of the near-eye display device of the present application.

[0034] FIG4 is a simulated optical path diagram of the second prism of the near-eye display device of the present application when β=0°, R=0 um, and r=0 um.

[0035] FIG5 is an overall forward simulated irradiance diagram of the second prism of the near-eye display device of the present application when β=0°, R=0um, and r=0um (the threshold energy is not reduced).

[0036] FIG6 is an overall forward simulated irradiance diagram of the second prism of the near-eye display device of the present application when β=0°, R=0um, and r=0um (after reducing the threshold energy).

[0037] FIG7 is a stray light simulation optical path diagram (a) and a partial enlarged diagram of part B (b) of the second prism of the near-eye display device of the present application when β=0°, R=0um, and r=0um.

[0038] FIG8 is a diagram of the overall forward simulated irradiance of stray light of the second prism of the near-eye display device of the present application when β=0°, R=0um, and r=0um.

[0039] FIG9 is a simulated optical path diagram of the second prism of the near-eye display device of the present application when β=0°, R=25 um, and r=25 um.

[0040] FIG10 is an overall forward simulated irradiance diagram of the second prism of the near-eye display device of the present application when β=0°, R=25um, and r=25um (the threshold energy is not reduced).

[0041] FIG11 is an overall forward simulated irradiance diagram of the second prism of the near-eye display device of the present application when β=0°, R=25um, and r=25um (after reducing the threshold energy).

[0042] FIG12 is a diagram (a) of the stray light forward simulated irradiance of the second prism of the near-eye display device of the present application when β=0°, R=25um, and r=25um and a partial enlarged diagram of part C (b).

[0043] FIG13 is a forward simulated irradiance diagram of the stray light smear of the second prism of the near-eye display device of the present application when β=0°, R=25um, and r=25um.

[0044] FIG14 is a simulated optical path diagram of the second prism of the near-eye display device of the present application when β=12°, R=5um, and r=5um.

[0045] FIG15 is an overall forward simulated irradiance diagram of the second prism of the near-eye display device of the present application when β=12°, R=5um, and r=5um (the threshold energy is not reduced).

[0046] FIG16 is an overall forward simulated irradiance diagram of the second prism of the near-eye display device of the present application when β=12°, R=5um, and r=5um (after reducing the threshold energy).

[0047] FIG17 is a stray light simulation optical path diagram (a) and a partial enlarged diagram of part D (b) of the second prism of the near-eye display device of the present application when β=12°, R=5um, and r=5um.

[0048] FIG18 is a forward simulated irradiance diagram of the stray light smear of the second prism of the near-eye display device of the present application when β=12°, R=5um, and r=5um.

[0049] Explanation of the accompanying drawings: 1. Display chip; 2. Imaging prism unit; 3. Second prism; 4. Imaging lens unit. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0051] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art in the art of this application. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0052] As shown in FIG1-3, a thin and light near-eye display device capable of eliminating stray light includes a display chip 1, an imaging prism unit 2, a second prism 3, an imaging lens unit 4, and an aperture, wherein:

[0053] The imaging prism unit 2 includes a first prism and a film system unit, wherein the first prism has a first optical surface, a second optical surface, and a third optical surface, and the film system unit is located between the first prism and the second prism 3;

[0054] Display chip 1 is disposed near the third optical surface of the first prism and is used to provide imaging light;

[0055] The second prism 3 is a Fresnel prism and is disposed close to the second optical surface of the first prism. The Fresnel surface of the second prism 3 faces the human eye and meets the following conditions:

[0056] sin(β)*n>sin(max(aor)) or sin(β)*n <sin(min(aor));

[0057] r / pitch < 0.05;

[0058] R / pitch < 0.05;

[0059] Wherein, β represents the draft angle of each tooth, aor represents the angle range between the tooth top and tooth bottom of each tooth draft angle and the line connecting any point of the aperture and the normal line of the aperture, max(aor) represents the maximum value of aor, min(aor) represents the minimum value of aor, n represents the refractive index of the material of the Fresnel prism, pitch represents the tooth width of each tooth, r represents the chamfer radius of the tooth bottom of each tooth, and R represents the chamfer radius of the tooth tip of each tooth;

[0060] The imaging lens unit 4 is arranged close to the first optical surface of the first prism, and a first semi-transparent and semi-reflective film is provided on the side facing away from the imaging prism unit 2;

[0061] The imaging light emitted by the display chip 1 enters the imaging prism unit 2, is reflected by the film system unit to the imaging lens unit 4, and then reflected back to the imaging prism unit 2 by the first semi-transparent and semi-reflective film and sequentially passes through the second prism 3 and the aperture to enter the human eye.

[0062] As shown in Figure 1, the implementation principle of the near-eye display device is that the imaging light emitted by the display chip 1 enters the first prism through the third optical surface of the first prism. Since the exit angle of some light is greater than the total reflection angle, the light is totally reflected on the surface of the first prism away from the human eye, that is, the first reflection is performed on the first optical surface of the first prism, and the imaging light is reflected to the second optical surface of the first prism. The film system unit is arranged between the second optical surface of the first prism and the second prism 3, so that it can be reflected for the second time on the second optical surface of the first prism, and then transmitted through the first optical surface of the first prism into the imaging lens unit 4. The imaging lens unit 4 is provided with a first semi-transparent and semi-reflective film, which reflects the imaging light back to the imaging prism unit 2, and then passes through the imaging prism unit 2 and the second prism 3 in turn to reach the aperture and enter the human eye to form a virtual image. The aperture in the near-eye display device is the position of the human eye, or the aperture is located between the second prism 3 and the human eye.

[0063] The display chip 1 can be an organic light-emitting diode (OLED) display, a liquid crystal on silicon (LCOS) display, a micro light-emitting diode (MicroLED) display, a digital light processing (DLP) display, or a laser beam scanning (LBS) display. An OLED display is preferred.

[0064] The imaging prism unit 2 includes a first prism and a film unit. The first prism can be made of either plastic or glass. The film unit is located between the second optical surface of the first prism and the second prism 3. It can be attached to the first prism or the second prism 3, or it can be plated on the first prism or the second prism 3. The film unit functions to reflect (or partially reflect) the imaging light emitted by the display chip 1 when it first reaches the second optical surface of the first prism, while allowing the light reflected from the imaging lens unit 4 to pass through the imaging prism unit 2.

[0065] The second prism 3 is a Fresnel prism, which can be made of plastic or glass, and the Fresnel surface is set towards the human eye. The stray light risk of the Fresnel prism is reduced by adjusting the draft angle β of the Fresnel prism while minimizing the values ​​of the chamfer r and R, thereby achieving the purpose of optimizing stray light in the near-eye display device. As shown in Figure 3, each tooth of the Fresnel prism can be the same or different. When the above range is met, the draft angle β, pitch, r and R of each tooth can be the same or different values. In the figure, n1 represents the incident angle of the Fresnel surface of the Fresnel prism, and n2 represents the exit angle of the Fresnel surface of the Fresnel prism, which is determined by the refractive index n of the material of the Fresnel prism. The units of β and aor are °, and the units of pitch, r and R are mm.

[0066] The imaging lens unit 4 is composed of a series of lenses with aberration correction and light path reflection functions. The material of each lens can be either glass or plastic, including but not limited to the following types: spherical lens, aspherical lens, free-form surface lens, Fresnel lens, flat lens, etc., preferably a spherical lens, and a first semi-transparent and semi-reflective film is provided on the side away from the imaging prism unit 2. The first semi-transparent and semi-reflective film can be realized by coating or sticking, and the transmission-reflection ratio can be 1:9 to 9:1, which can make the light partially reflect and partially transmit, and the ratio of reflection and transmission can depend on the angle of the incident light.

[0067] The near-eye display device includes a display chip, an imaging prism unit, a second prism, an imaging lens unit, and an aperture. The second prism adopts a Fresnel prism. By adjusting the draft angle β, pitch, r, and R values ​​of each tooth on the Fresnel prism, the generated total reflection stray light is adjusted outside the field of view to reduce smear and reduce the risk of stray light, thereby achieving the purpose of optimizing stray light of the near-eye display device. Moreover, by adopting the Fresnel prism, compared with the conventional technology using ordinary prisms, the overall weight can be further reduced while ensuring the imaging light path and improving the display effect. The bottom of the device can also be made thinner. Based on the prism total reflection architecture, the imaging light emitted by the display chip is incident on the imaging prism unit and then reflects multiple times to achieve light path folding. On the basis of ensuring sufficient optical path of the imaging light, the imaging prism unit is avoided from being too large, which would lead to the problem of increasing the overall volume of the near-eye display device. This is conducive to further achieving overall lightweight and thinness, and improving user comfort, experience, and aesthetics.

[0068] In one embodiment, the pitch value of the Fresnel surface of the second prism 3 is in the range of 0.15 mm to 0.6 mm, and the value ranges of r and R are both in the range of 0.005 mm to 0.02 mm.

[0069] Among them, when pitch, r and R meet the above value ranges, good display effects can be obtained and processing is facilitated. In addition, when meeting the above value ranges, the smaller the value, the better.

[0070] In one embodiment, the film system unit includes at least one of a second transflective film, a reflective polarizing film, a quarter-wave plate, and an absorbing polarizing film.

[0071] The film assembly unit can be a reflective polarizing film, or a combination of a reflective polarizing film and a quarter-wave plate, in which case the quarter-wave plate can be positioned between the reflective polarizing film and the first prism. Alternatively, the film assembly unit can be a second transflective film, etc., and the specific configuration can be adjusted based on actual needs. The second transflective film can have a transmittance-to-reflection ratio of 1:9 to 9:1, enabling light to be partially reflected and partially transmitted, with the ratio of reflection to transmission determined by the angle of the incident light.

[0072] In one embodiment, the included angle between the first optical surface and the second optical surface of the first prism is 15° to 35°.

[0073] Among them, if the angle between the first optical surface and the second optical surface is too small, the imaging light emitted by the display chip 1 will be reflected back and forth multiple times in the first prism, or the imaging light emitted by the display chip 1 cannot meet the requirement of total reflection on the first prism. If the angle between the first optical surface and the second optical surface is too large, the imaging light emitted by the display chip 1 can only be reflected once in the first prism before being emitted, and the requirement of folding the light path by two reflections cannot be met. To this end, in this embodiment, the angle between the first optical surface and the second optical surface of the first prism is within the range of 15° to 35°, which can ensure that the imaging light emitted by the display chip 1 can achieve the requirement of two reflections in the first prism, which helps to obtain a small and lightweight near-eye display device.

[0074] In one embodiment, the air gap between the imaging prism unit 2 and the imaging lens unit 4 is 0.01 mm to 1.0 mm. This ensures that the air gap required for total internal reflection is maintained while reducing the overall thickness of the device. If the gap is less than 0.01 mm, the air gap cannot be guaranteed to exist within a certain tolerance. If the gap is greater than 1.0 mm, the overall thickness of the device increases, which is not conducive to achieving lightweight and thinness.

[0075] In one embodiment, the imaging lens unit 4 is a curved lens, and the curvature radius R11 of the mirror surface close to the first prism satisfies R11 ≥ 150 mm or R11 ≤ -150 mm, the curvature radius R12 of the mirror surface away from the first prism satisfies 40 mm ≤ R12 ≤ 75 mm, and the curvature radius R13 of the third optical surface of the first prism satisfies R13 ≥ 22 mm or R13 ≤ -100 mm. Preferably, the refractive index of the imaging lens unit 4 is 1.50 to 1.90, and the Abbe number is 38.0 to 85.0. It should be noted that any surface of the above-mentioned lenses in this embodiment is an even aspheric surface type, and all satisfy the following aspheric formula:

[0076] Among them, z is the sag height, Y is the center height of the lens, k is the cone coefficient, C is the curvature, a i is the 2i-th order aspheric coefficient, and N is a positive integer.

[0077] In one embodiment, the refractive index of the first prism and the second prism 3 are both 1.45 to 1.75, and the Abbe number is both 18.0 to 60.0. The smaller the Abbe number, the better, as it can correct chromatic aberration.

[0078] In one embodiment, the thin and lightweight near-eye display device capable of eliminating stray light further includes a compensation lens unit, which is disposed near the first transflective film and has a focal length opposite to that of the imaging lens unit 4 .

[0079] The compensating lens unit is composed of a series of lenses with aberration correction functions. Its focal length is opposite to that of the imaging lens unit 4 to correct the aberrations produced by the human eye when viewing the outside world through the imaging lens unit 4, ensuring that the aberrations of the outside world viewed by the human eye are sufficiently small. The lenses in the compensating lens unit can be made of plastic or glass, and the number of lenses is not limited. Each lens includes but is not limited to the following types: spherical lenses, aspherical lenses, free-form surface lenses, Fresnel lenses, flat plate lenses, etc., preferably spherical lenses. It should be noted that when the lenses in the above-mentioned compensating lens unit and imaging lens unit 4 are aspherical lenses, their mirror surfaces satisfy the even-order aspheric formula.

[0080] In one embodiment, the focal length of the imaging lens unit 4 is 10 mm to 25 mm. This ensures that the device has a reasonable optical path and prevents the display chip 1 from sinking and interfering with the surface of the first prism. It also prevents the optical path from being too long, which would make the device too large and impractical. Preferably, the focal length of the imaging lens unit 4 is 11 mm to 23 mm.

[0081] In one embodiment, the display chip 1 is further moved relative to the imaging prism unit 2 to adjust the diopter.

[0082] Among them, by changing the distance between the display chip 1 and the third optical surface of the first prism, the different imaging positions of the imaging light can be changed to achieve diopter adjustment, thereby adapting to wearers with different myopia degrees.

[0083] The following is a detailed description through specific embodiments to facilitate understanding.

[0084] The parameters of each optical element in this embodiment are shown in Table 1 below.

[0085] Table 1

[0086] In Table 1, surface number S0 represents the object plane, surface number S1 represents the aperture, surface number S2 represents the Fresnel surface of the Fresnel prism, surface number S3 represents the plane on the Fresnel prism close to the first prism, surface numbers S4 and S10 represent the second optical surface of the first prism, surface numbers S5, S9, and S11 represent the first optical surface of the first prism, surface numbers S6 and S8 represent the mirror surfaces of the imaging lens unit close to the first prism, and surface number S7 represents the mirror surface of the imaging lens unit farthest from the first prism. A curvature radius of "-" indicates a curvature direction opposite to that of surface S6 or surface S8. Surface number S12 represents the third optical surface of the first prism, surface number S13 represents the surface of the display chip close to the first prism, and surface number S14 represents the surface of the display chip farthest from the first prism. The pitch width of the second prism is 0.25 mm.

[0087] As shown in Figures 4-6, when the second prism 3 uses an ideal Fresnel prism (β = 0°, R = 0um and r = 0um), there is a very obvious ghosting phenomenon. After lowering the threshold energy, a ghost similar to the shape of the pixel can be seen in the picture. Specifically, it is shown as the bright spot at the bottom of Figure 6 (invalid light path imaging, interfering with the normal picture). Lowering the threshold energy means lowering the order of magnitude of the brightness. As shown in Figures 7 and 8, Figure 7 is a stray light simulation light path diagram of the near-eye display device when β = 0°, R = 0um, and r = 0um. It can be seen from Figure 8 that the source of the ghosting is that the light is totally reflected at the sagittal height of the Fresnel prism, and the energy of the ghosting is about 1 / 40 of the pixel.

[0088] As shown in Figures 9-13, when the second prism 3 uses an ordinary Fresnel prism, due to the chamfers (β = 0°, R = 25um and r = 25um) that will appear during the actual processing of the ordinary Fresnel prism, a smearing phenomenon will occur, that is, a ghost image will be generated. Figure 10 shows the overall forward simulated irradiance of the near-eye display device when β = 0°, R = 25um, and r = 25um. However, since the imaging irradiance is many times greater than the ghost image irradiance generated by stray light, the ghost image irradiance is made more obvious by reducing the threshold energy in Figure 11. Figure 12 shows the stray light simulated light path diagram of the near-eye display device when β = 0°, R = 25um, and r = 25um. As can be seen from Figure 13, the source of the smear is the refraction of light at the chamfer of the Fresnel prism, and the energy of the smear is approximately 1 / 125 of the pixel.

[0089] As shown in Figures 14-18, the draft angle β, r and R value of the second prism are adjusted. For example, in this embodiment, β = 12°, R = 5um, and r = 5um. Figure 14 shows the simulated optical path diagram of the near-eye display device when β = 12°, R = 5um, and r = 5um. Figure 15 shows the overall forward simulated irradiance when β = 12°, R = 5um, and r = 5um. However, since the imaging irradiance is many times larger than the ghost image irradiance generated by stray light, the ghost image irradiance is made more obvious by lowering the threshold energy in Figure 16. Figure 17 shows the stray light simulated optical path diagram of the near-eye display device when β = 12°, R = 5um, and r = 5um. It can be seen from Figure 18 that the ghost image disappears, the energy of the trailing image becomes 1 / 540 of the pixel, and the stray light is significantly improved.

[0090] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above-described embodiments merely represent specific and detailed examples of the present application and should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A thin and light near-eye display device capable of eliminating stray light, wherein: The thin and light near-eye display device capable of eliminating stray light comprises a display chip (1), an imaging prism unit (2), a second prism (3), an imaging lens unit (4) and a stop, wherein: The imaging prism unit (2) comprises a first prism and a film system unit, the first prism having a first optical surface, a second optical surface and a third optical surface, and the film system unit is located between the first prism and the second prism (3); The display chip (1) is arranged close to the third optical surface of the first prism and is used to provide imaging light; The second prism (3) is a Fresnel prism and is arranged close to the second optical surface of the first prism. The Fresnel surface of the second prism (3) faces the human eye and meets the following conditions: sin(β)*n>sin(max(aor)) or sin(β)*n <sin(min(aor)); r / pitch < 0.05; R / pitch<0.05; Wherein, β represents the draft angle of each tooth, aor represents the angle range between the tooth top and tooth bottom of the draft angle of each tooth and the connecting line of any point of the aperture and the normal line of the aperture, max(aor) represents the maximum value of aor, min(aor) represents the minimum value of aor, n represents the material refractive index of the Fresnel prism, pitch represents the tooth width of each tooth, r represents the chamfer radius of the tooth bottom of each tooth, and R represents the chamfer radius of the tooth tip of each tooth; The imaging lens unit (4) is arranged close to the first optical surface of the first prism, and a first semi-transparent and semi-reflective film is arranged on the side facing away from the imaging prism unit (2); The imaging light emitted by the display chip (1) enters the imaging prism unit (2), is reflected by the film system unit to the imaging lens unit (4), is then reflected by the first semi-transparent and semi-reflective film back to the imaging prism unit (2), and sequentially passes through the second prism (3) and the aperture to enter the human eye.

2. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The pitch value range of the Fresnel surface of the second prism (3) is 0.15 mm to 0.6 mm, and the value ranges of r and R are both 0.005 mm to 0.02 mm.

3. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The film system unit includes at least one of a second semi-transmissive and semi-reflective film, a reflective polarizing film, a quarter wave plate and an absorbing polarizing film.

4. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The included angle between the first optical surface and the second optical surface of the first prism is 15° to 35°.

5. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The air gap between the imaging prism unit (2) and the imaging lens unit (4) is 0.01 mm to 1.0 mm.

6. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The imaging lens unit (4) is a curved lens, and the curvature radius R11 of the mirror surface close to the first prism satisfies R11≥150mm or R11≤-150mm, the curvature radius R12 of the mirror surface away from the first prism satisfies 40mm≤R12≤75mm, and the curvature radius R13 of the third optical surface of the first prism satisfies R13≥22mm or R13≤-100mm.

7. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The refractive index of the first prism and the second prism (3) are both 1.45-1.75, and the Abbe number is both 18.0-60.

0.

8. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The thin and light near-eye display device capable of eliminating stray light further comprises a compensation lens unit, the compensation lens unit is arranged close to the first semi-transmissive and semi-reflective film, and the focal length of the compensation lens unit has an opposite value to the focal length of the imaging lens unit (4).

9. The thin and light near-eye display device capable of eliminating stray light according to claim 8, wherein: The focal length of the imaging lens unit (4) is 10 mm to 25 mm.

10. The thin and light near-eye display device capable of eliminating stray light according to claim 1, wherein: The display chip (1) moves relative to the imaging prism unit (2) to adjust the diopter.

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