Lightweight near-eye display apparatus

Abstract

A lightweight near-eye display apparatus, comprising: a first imaging prism unit (2), comprising a first prism and a film system unit, the first prism having a first optical surface (21), a second optical surface (22), and a third optical surface (23), and the film system unit being located between the first prism and a second imaging prism unit (5); a display image source (1), which is arranged close to the third optical surface (23) of the first prism and is used for providing imaging light; a first imaging lens unit (3), which is arranged close to the first optical surface (21) of the first prism, a first semi-transparent semi-reflective film being provided on the side of the first imaging lens unit (3) facing away from the first imaging prism unit (2); a compensation lens unit (4), which is arranged close to the first semi-transparent semi-reflective film, the focal length of the compensation lens unit (4) and the focal length of the first imaging lens unit (3) having opposite values; and the second imaging prism unit (5), which is arranged close to the second optical surface (22) of the first prism and comprises at least one Fresnel lens. Said apparatus is small and lightweight, and the comfort of use and experience of a user are improved.

Description

A lightweight near-eye display device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on August 14, 2023, with application number 202322181896.5, 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 lightweight near-eye display device. Background Art

[0004] AR display technology, also known as virtual reality display technology, uses optical components to achieve the superposition of virtual and real images. In modern AR products, weight and thickness are important indicators of product strength. Therefore, how to make the product lighter and thinner while maintaining good display quality is an urgent problem to be solved.

[0005] An existing optical solution uses a total reflection prism to transmit image light, combined with a dioptric lens to achieve near-eye display. Projected light from the image source is incident on a first prism, undergoes multiple reflections, and then enters the first lens. After reflection from the first lens, it passes through the first and second prisms before entering the eye. The problem with this solution is that the use of multiple prisms makes AR products heavier and thicker, far from the lightweight and thinness AR products strive for, and it cannot correct for human eye aberrations.

[0006] Summary of the Invention

[0007] The purpose of this application is to address the above-mentioned problems and propose a lightweight near-eye display device that can achieve the overall miniaturization and lightweight of the device, thereby improving the user's comfort and experience.

[0008] To achieve the above objectives, the technical solutions adopted in this application are:

[0009] The present application proposes a lightweight near-eye display device, comprising a display image source, a first imaging prism unit, a first imaging lens unit, a compensation lens unit, and a second imaging prism unit, wherein:

[0010] A first 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 imaging prism unit;

[0011] A display image source is disposed near the third optical surface of the first prism and is used to provide imaging light;

[0012] A first 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 first imaging prism unit;

[0013] a compensation lens unit, disposed near the first semi-transmissive and semi-reflective film, wherein the focal length of the compensation lens unit is opposite to the focal length of the first imaging lens unit;

[0014] a second imaging prism unit, disposed adjacent to the second optical surface of the first prism, and comprising at least one Fresnel lens;

[0015] The imaging light emitted by the display image source enters the first prism through the third optical surface, is reflected for the first time by the first optical surface, and for the second time by the second optical surface, and then is transmitted through the first optical surface into the first imaging lens unit, is reflected for the third time by the first semi-transparent and semi-reflective film, and then passes through the first imaging prism unit and the second imaging prism unit in sequence to enter the human eye.

[0016] Preferably, the included angle between the first optical surface and the second optical surface of the first prism is 15° to 35°.

[0017] 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.

[0018] Preferably, the transmission-reflection ratio of the first semi-transmissive and semi-reflective membrane to the second semi-transmissive and semi-reflective membrane is 1:9 to 9:1.

[0019] Preferably, the focal length f1 of the first imaging lens unit satisfies 10 mm ≤ f1 ≤ 25 mm.

[0020] Preferably, the air gap between the first imaging prism unit and the first imaging lens unit is 0.01 mm to 1.0 mm.

[0021] Preferably, the display image source is further moved relative to the first imaging prism unit to perform diopter adjustment.

[0022] Preferably, a second imaging lens unit is further provided between the display image source and the first imaging prism unit, and a focal length f2 of the second imaging lens unit satisfies f2 ≥ 50 mm or f2 ≤ -50 mm.

[0023] Preferably, the display image source and the second imaging lens unit also move synchronously relative to the first imaging prism unit to perform diopter adjustment.

[0024] Preferably, the first imaging lens unit is a curved lens, and the curvature radius R11 of the mirror surface close to the first prism satisfies R11≥100mm or R11≤-100mm, the curvature radius R12 of the mirror surface away from the first prism satisfies 40mm≤R12≤80mm, the refractive index is 1.45~1.90, and the Abbe number is 35.0~85.0.

[0025] Preferably, the second imaging prism unit includes a Fresnel lens, the angle between the tooth base line of two adjacent teeth in the Fresnel lens and the corresponding tooth width direction is 15° to 35°, the tooth width of the Fresnel lens is greater than or equal to 0.1 mm, the draft angle of the teeth of the Fresnel lens is 60° to 120°, and the refractive index of the Fresnel lens and the first prism are both 1.45 to 1.75, and the Abbe number is both 18.0 to 60.0.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The near-eye display device includes a display image source, a first imaging prism unit, a first imaging lens unit, a compensation lens unit, and a second imaging prism unit. Based on a prism total reflection architecture, the imaging light emitted by the display image source is incident on the first imaging prism unit and then reflected twice, thereby realizing light path folding. On the basis of ensuring that the imaging light has a sufficient optical path, it avoids the problem that the volume of the first imaging prism unit is too large due to excessive reflections, thereby increasing the overall volume of the near-eye display device, and is conducive to achieving lightness and thinness. By designing the second imaging prism unit as a whole or part of a Fresnel lens, the near-eye display device is further reduced while ensuring that the optical path and performance remain unchanged. The overall weight can also make the bottom of the near-eye display device thinner; in addition, the aberration is corrected by the compensation lens unit, and its focal length has an opposite value to the focal length of the first imaging lens unit to correct the aberration generated by the human eye seeing the outside world through the first imaging lens unit, ensuring that the aberration of the human eye seeing the outside world is small enough. Compared with the prior art, the device ensures that the imaging optical path is completely equivalent, while the overall weight is reduced by about 20%, and the bottom thickness is greatly reduced. For example, the overall weight of the near-eye display device of the present application is 6.5g and the thickness is about 3.8mm. The weight before the reduction is about 8g and the thickness is about 8.7mm. The overall shape is closer to glasses, which improves the user's comfort, experience and aesthetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a schematic structural diagram of a lightweight near-eye display device of the present application;

[0029] FIG2 is a schematic structural diagram of a second imaging prism unit of the present application;

[0030] FIG3 is a partial enlarged view of the second imaging prism unit of the present application.

[0031] Explanation of the accompanying drawings: 1. Display image source; 2. First imaging prism unit; 3. First imaging lens unit; 4. Compensating lens unit; 5. Second imaging prism unit; 6. Aperture; 21. First optical surface; 22. Second optical surface; 23. Third optical surface. DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] As shown in FIG1 , a lightweight near-eye display device includes: a display image source 1, a first imaging prism unit 2, a first imaging lens unit 3, a compensation lens unit 4, and a second imaging prism unit 5, wherein:

[0035] The first imaging prism unit 2 includes a first prism and a film system unit. The first prism has a first optical surface 21, a second optical surface 22, and a third optical surface 23. The film system unit is located between the first prism and the second imaging prism unit 5.

[0036] Display image source 1, disposed near the third optical surface 23 of the first prism, for providing imaging light;

[0037] The first imaging lens unit 3 is disposed close to the first optical surface 21 of the first prism, and a first semi-transparent and semi-reflective film is disposed on a side facing away from the first imaging prism unit (located at the arc line position of the first imaging lens unit 3 in FIG1 );

[0038] a compensation lens unit 4, disposed close to the first semi-transmissive and semi-reflective film, wherein the focal length of the compensation lens unit 4 is opposite to the focal length of the first imaging lens unit 3;

[0039] The second imaging prism unit 5 is arranged near the second optical surface 22 of the first prism and includes at least one Fresnel lens;

[0040] The imaging light emitted by the display image source 1 enters the first prism through the third optical surface 23 of the first prism, is reflected for the first time by the first optical surface 21 of the first prism, is reflected for the second time by the second optical surface 22 of the first prism, and then is transmitted through the first optical surface 21 of the first prism into the first imaging lens unit 3, is reflected for the third time by the first semi-transparent and semi-reflective film, and then is incident on the human eye through the first imaging prism unit 2 and the second imaging prism unit 5 in sequence.

[0041] As shown in Figure 1, the implementation principle of the near-eye display device is that the imaging light emitted by the display image source 1 enters the first prism through the third optical surface 23 of the first prism, is reflected for the first time at the first optical surface 21 of the first prism, and is reflected to the second optical surface 22 of the first prism. The film system unit is arranged between the second optical surface 22 of the first prism and the second imaging prism unit 5, so that the imaging light can be reflected for the second time at the second optical surface 22 of the first prism, and the imaging light is then transmitted through the first optical surface 21 of the first prism into the first imaging lens unit 3. The first imaging lens unit 3 is provided with a first semi-transparent and semi-reflective film, which reflects the imaging light back to the first imaging prism unit 2, and then passes through the first imaging prism unit 2 and the second imaging prism unit 5 in sequence to enter the human eye.

[0042] The display image source 1 can be any one of an OLED (Organic Light-Emitting Diode) display, an LCOS (Liquid Crystal On Silicon) display, a Microled display, a DLP (Digital Light Processing) display, and an LBS (Laser Beam Scanning) display, preferably an OLED display.

[0043] As shown in FIG1 , the lightweight near-eye display device may further include an aperture 6 , which is located between the second imaging prism unit 5 and the human eye.

[0044] The first imaging prism unit 2 includes a first prism and a film system unit, wherein the first prism can be made of plastic or glass. The film system unit is located between the second optical surface 22 of the first prism and the second imaging prism unit 5. It can be attached to the first prism or the second imaging prism unit 5, or it can be plated on the first prism or the second imaging prism unit 5. The film system unit causes the imaging light emitted by the display image source 1 to be reflected (or partially reflected) when it first reaches the second optical surface 22 of the first prism, and the imaging light is reflected by the first imaging lens unit 3 and transmitted when it reaches the second optical surface 22 of the first prism for the second time.

[0045] The first imaging lens unit 3 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 first imaging prism unit 2. The first semi-transparent and semi-reflective film can be realized by coating or sticking.

[0046] The compensating lens unit 4 can be composed of a series of lenses with aberration correction capabilities. Their focal lengths are opposite to those of the first imaging lens unit 3. This corrects the aberrations produced when the human eye sees the outside world through the first imaging lens unit 3, ensuring that the aberrations seen by the human eye are sufficiently minimal. The lenses in the compensating lens unit 4 can be made of plastic or glass, and the number of lenses is not limited. The lenses include, but are not limited to, the following types: spherical lenses, aspherical lenses, free-form surface lenses, Fresnel lenses, and flat lenses, with spherical lenses being preferred.

[0047] The second imaging prism unit 5 is composed of a series of prisms that provide aberration correction and compensate for optical path differences between the upper and lower fields of view. At least one prism is a Fresnel lens, with its Fresnel surface facing the eye. The other prisms in the second imaging prism unit 5 can be made of plastic or glass, including but not limited to the following types: spherical lenses, aspherical lenses, free-form surface lenses, Fresnel lenses, and flat plate lenses, with aspherical lenses being preferred.

[0048] In one embodiment, the included angle between the first optical surface 21 and the second optical surface 22 of the first prism is 15° to 35°.

[0049] If the angle between the first optical surface 21 and the second optical surface 22 is too small, the imaging light emitted by the display image source 1 will be reflected back and forth multiple times within the first prism, or the requirement for the imaging light emitted by the display image source 1 to be fully reflected on the first prism cannot be met. If the angle between the first optical surface 21 and the second optical surface 22 is too large, the imaging light emitted by the display image source 1 can only be reflected once within the first prism before being emitted, and the requirement for optical path folding by two reflections cannot be met. To this end, in this embodiment, the angle between the first optical surface 21 and the second optical surface 22 of the first prism is within the range of 15° to 35°, which can ensure that the imaging light emitted by the display image source 1 is reflected twice within the first prism, thereby helping to obtain a small and lightweight near-eye display device.

[0050] In one embodiment, the film assembly unit includes at least one of a second transflective film, a reflective polarizing film, a quarter-wave plate, and an absorptive polarizing film. For example, the film assembly unit may 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 may be positioned between the reflective polarizing film and the first prism, or the film assembly unit may be a second transflective film, etc. The specific configuration can be adjusted based on actual needs.

[0051] In one embodiment, the transflective film (including the first and second transflective films) described herein has a transmittance-to-reflection ratio of 1:9 to 9:1. The transflective film partially reflects and partially transmits light, with the ratio of reflection to transmission varying depending on the angle of incidence of the light.

[0052] In one embodiment, the focal length f1 of the first imaging lens unit 3 satisfies 10 mm ≤ f1 ≤ 25 mm, preferably 11 mm ≤ f1 ≤ 23 mm.

[0053] In one embodiment, the air gap between the first imaging prism unit 2 and the first imaging lens unit 3 is 0.01 mm to 1.0 mm.

[0054] In one embodiment, the display image source 1 can be further moved relative to the first imaging prism unit 2 to perform diopter adjustment.

[0055] By changing the distance between the display image source 1 and the third optical surface 23 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.

[0056] In one embodiment, a second imaging lens unit is further provided between the display image source 1 and the first imaging prism unit 2, and the focal length f2 of the second imaging lens unit satisfies f2 ≥ 50 mm or f2 ≤ -50 mm, preferably f2 ≥ 60 mm or f2 ≤ -60 mm.

[0057] The second imaging lens unit includes at least one lens, each of which can be made of plastic or glass. The number of lenses is not limited, and includes, but is not limited to, the following types: spherical lenses, aspherical lenses, free-form lenses, Fresnel lenses, and flat lenses, with spherical lenses being preferred. The second imaging lens unit is located on the light-exiting side of the display image source 1 and has a properly configured focal length. It corrects aberrations and distributes refractive errors, resulting in higher image quality and minimized optical distortion. Furthermore, because the second imaging lens unit constrains and converges the imaging light before it enters the first imaging prism unit 2, it facilitates diopter adjustment of the display image source 1 with a smaller angle and movement.

[0058] In one embodiment, the display image source 1 and the second imaging lens unit as a whole can be moved relative to the first imaging prism unit 2 to adjust the diopter.

[0059] Among them, by changing the distance between the display image source 1 and the second imaging lens unit relative to the third optical surface 23 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.

[0060] In one embodiment, the first imaging lens unit 3 is a curved lens, wherein the radius of curvature R11 of the mirror surface close to the first prism satisfies R11 ≥ 100 mm or R11 ≤ -100 mm, the radius of curvature R12 of the mirror surface away from the first prism satisfies 40 mm ≤ R12 ≤ 80 mm, the refractive index is 1.45 to 1.90, and the Abbe number is 35.0 to 85.0. Preferably, R11 ≥ 150 mm or R11 ≤ -150 mm, 40 mm ≤ R12 ≤ 75 mm, the refractive index is 1.50 to 1.90, and the Abbe number is 38.0 to 85.0.

[0061] It should be noted that any surface of the lenses mentioned above in this application that is an even aspheric surface type satisfies the following aspheric formula:

[0062] 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.

[0063] In one embodiment, the second imaging prism unit 5 includes a Fresnel lens, the angle between the tooth base line of two adjacent teeth in the Fresnel lens and the corresponding tooth width direction is 15° to 35°, the tooth width of the Fresnel lens is greater than or equal to 0.1 mm, the draft angle of the teeth of the Fresnel lens is 60° to 120°, and the refractive index of the Fresnel lens and the first prism are both 1.45 to 1.75, and the Abbe number is both 18.0 to 60.0.

[0064] As shown in Figures 2 and 3, the second imaging prism unit 5 includes a Fresnel lens. The Fresnel lens is tilted, with one side being a light surface and the other side being inscribed with concentric circles from small to large (i.e., the Fresnel surface). The light surface is parallel to the second optical surface 22 of the first prism, and the Fresnel surface faces the human eye. The angle range between the line connecting the tooth bases of two adjacent teeth of the Fresnel lens and the corresponding tooth width direction is the same as the angle between the first optical surface 21 and the second optical surface 22 of the first prism. The material selection range is also the same as that of the first prism, which can better correct the main ray deflection problem caused by the first prism. The tooth width range is greater than 0.1mm, which can reduce the risk of stray light and reduced transmittance caused by too small a tooth width. The draft angle of 60° to 120° can better match the main ray angle of different fields of view, reduce the risk of stray light, and thus improve imaging quality. As in this embodiment, the angle α between the tooth bottom line connecting two adjacent teeth of the Fresnel lens and the direction of the corresponding tooth width is 27°, the refractive index of the Fresnel lens and the first prism are both 1.72, the Abbe number is both 29.5, the tooth width h is 0.25 mm, the direction of the tooth width h is the direction of the corresponding tooth width, and the tooth draft angle is 93°. The tooth width and draft angle of each tooth are different, and can also be adjusted according to actual needs.

[0065] The imaging light emitted by the display image source 1 of the near-eye display device is incident on the first imaging prism unit 2 and is reflected twice to achieve light path folding. On the basis of ensuring that the imaging light has sufficient optical path, it can avoid the problem of excessive reflections making the first imaging prism unit 2 too large, thereby increasing the overall volume of the near-eye display device, which is conducive to achieving lightweight and thinness; by designing the second imaging prism unit 5 as a Fresnel lens in whole or in part, the overall weight of the near-eye display device is further reduced while ensuring that the optical path and performance remain unchanged, and the bottom of the near-eye display device can also be made thinner; in addition, aberration correction is performed by using the compensation lens unit 4, and its focal length has an opposite value to the focal length of the first imaging lens unit 3, so as to correct the aberration generated by the human eye looking at the outside world through the first imaging lens unit 3, and ensure that the aberration of the human eye looking at the outside world is small enough. Compared with the existing technology, the device reduces the overall weight by about 20% and greatly reduces the bottom thickness while ensuring that the imaging optical path is completely equivalent. For example, the near-eye display device of the present application has an overall weight of 6.5g and a thickness of about 3.8mm. Before the weight reduction, it weighs about 8g and has a thickness of about 8.7mm. The overall shape is closer to glasses, which improves the user's comfort, experience and aesthetics.

[0066] 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.

[0067] 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 present invention. 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 invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A lightweight near-eye display device, comprising a display image source (1), a first imaging prism unit (2), a first imaging lens unit (3), a compensation lens unit (4) and a second imaging prism unit (5), wherein: The first imaging prism unit (2) comprises a first prism and a film system unit, the first prism having a first optical surface (21), a second optical surface (22) and a third optical surface (23), and the film system unit is located between the first prism and the second imaging prism unit (5); The display image source (1) is arranged close to the third optical surface (23) of the first prism and is used to provide imaging light; The first imaging lens unit (3) is arranged close to the first optical surface (21) of the first prism, and a first semi-transparent and semi-reflective film is arranged on the side facing away from the first imaging prism unit (2); The compensation lens unit (4) is close to the first semi-transparent and semi-reflective film The compensation lens unit (4) is configured such that the focal length of the compensation lens unit (4) is opposite to the focal length of the first imaging lens unit (3); The second imaging prism unit (5) is arranged close to the second optical surface (22) of the first prism, and comprises at least one Fresnel lens; The imaging light emitted by the display image source (1) enters the first prism through the third optical surface (23), is reflected for the first time by the first optical surface (21), is reflected for the second time by the second optical surface (22), is transmitted through the first optical surface (21) into the first imaging lens unit (3), is reflected for the third time by the first semi-transparent and semi-reflective film, and then is incident on the human eye through the first imaging prism unit (2) and the second imaging prism unit (5) in sequence.

2. The lightweight near-eye display device according to claim 1, wherein: The angle between the first optical surface (21) and the second optical surface (22) is 15° to 35°.

3. The lightweight near-eye display device 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 lightweight near-eye display device according to claim 3, wherein: The transmittance-reflection ratio of the first semi-transmissive and semi-reflective film and the second semi-transmissive and semi-reflective film is in the range of 1:9 to 9:

1.

5. The lightweight near-eye display device according to claim 1, wherein: The focal length f1 of the first imaging lens unit (3) satisfies 10 mm ≤ f1 ≤ 25 mm.

6. The lightweight near-eye display device according to claim 1, wherein: The air gap between the first imaging prism unit (2) and the first imaging lens unit (3) is 0.01 mm to 1.0 mm.

7. The lightweight near-eye display device according to claim 1, wherein: The display image source (1) moves relative to the first imaging prism unit (2) to adjust the diopter.

8. The lightweight near-eye display device according to claim 1, wherein: A second imaging lens unit is further provided between the display image source (1) and the first imaging prism unit (2), and the focal length f2 of the second imaging lens unit satisfies f2≥50mm or f2≤-50mm.

9. The lightweight near-eye display device according to claim 8, wherein: The display image source (1) and the second imaging lens unit move synchronously relative to the first imaging prism unit (2) to adjust the diopter.

10. The lightweight near-eye display device according to claim 1, wherein: The first imaging lens unit (3) is a curved lens, and the curvature radius R11 of the mirror surface close to the first prism satisfies R11≥100mm or R11≤-100mm, and the curvature radius R12 of the mirror surface away from the first prism satisfies 40mm≤R12≤80mm, the refractive index is 1.45-1.90, and the Abbe number is 35.0-85.

0.

11. The lightweight near-eye display device according to claim 1, wherein: The second imaging prism unit (5) comprises a Fresnel lens, the angle between the tooth bottom connection line of two adjacent teeth in the Fresnel lens and the corresponding tooth width direction is 15° to 35°, the tooth width of the Fresnel lens is greater than or equal to 0.1 mm, the draft angle of the teeth of the Fresnel lens is 60° to 120°, and the refractive index of the Fresnel lens and the first prism are both 1.45 to 1.75, and the Abbe number is both 18.0 to 60.0.

Images