Near-to-eye display equipment

Abstract

The invention discloses a near-to-eye display device which comprises a control system, an illumination system and a projection system. The lighting system comprises a first driving module, a light-emitting part and a lighting module. The projection system comprises a second driving module, a display chip and a projection module; the first driving module and the second driving module are electrically connected to the control system, the light-emitting part is electrically connected to the first driving module, the display chip is electrically connected to the second driving module, and the display chip is connected between the illumination module and the projection module. The lighting module comprises a free-form surface prism, a dodging piece, a wedge-shaped prism and a right-angle prism which are sequentially arranged between the light-emitting piece and the display chip, and the refractive index n1 of the wedge-shaped prism is smaller than the refractive index n2 of the right-angle prism. Compared with the prior art, the light path complexity of the illumination module and the projection module is reduced, the energy utilization rate and the illumination uniformity of the illumination module and the projection module are improved, meanwhile, the size and the weight of the near-to-eye display equipment are effectively reduced, and the wearing experience of a user is improved.

Description

Technical Field

[0001] The present invention relates to the field of projection display technology, and in particular to a near-eye display device. Background Art

[0002] Existing near-eye display devices include an illumination system and a projection system. When using traditional refractive optical elements to design the illumination system and the projection system, there is a relatively low degree of design freedom, a relatively small amount of optimization, a relatively complex overall optical path, relatively low energy utilization and illumination uniformity, and the near-eye display device will be too large in size and weight.

[0003] In view of this, it is necessary to provide a near-eye display device to solve the above problems. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a near-eye display device, which can effectively solve the problems of large size and weight of near-eye display devices, complex projection optical path, and relatively low energy utilization and illumination uniformity.

[0005] To achieve the above-mentioned objectives, the present invention provides a near-eye display device, which includes a control system, an illumination system and a projection system; the illumination system includes a first driving module, a light-emitting element and a lighting module; the projection system includes a second driving module, a display chip and a projection module; the first driving module and the second driving module are electrically connected to the control system respectively, the light-emitting element is electrically connected to the first driving module, the display chip is electrically connected to the second driving module, the display chip is connected between the illumination module and the projection module, and the illumination module includes a free-form surface prism, a light homogenizing element, a wedge prism and a right-angle prism which are sequentially arranged between the light-emitting element and the display chip, and the refractive index n1 of the wedge prism is less than the refractive index n2 of the right-angle prism.

[0006] In a preferred embodiment, the free-form surface prism includes a first curved surface, a second curved surface and a third curved surface, the third curved surface is close to the light emitting element, the second curved surface is far from the light homogenizing element, and the first curved surface is close to the light homogenizing element.

[0007] In a preferred embodiment, a parabola is formed on the third curved surface, the curvature radius r1 of the parabola satisfies 2.5 mm≤r1≤5 mm, and the aperture R1 of the parabola satisfies 0.9 mm≤R1≤1.5 mm.

[0008] In a preferred embodiment, the second curved surface is a Fresnel surface, and the sawtooth depth h on the Fresnel surface satisfies 2.5 mm≤h≤5 mm.

[0009] In a preferred embodiment, the light homogenizer is an array lens or a DOE element.

[0010] In a preferred embodiment, the refractive index n1 of the wedge prism satisfies 1.51≤n1≤1.54, and the refractive index n2 of the right-angle prism satisfies 1.70≤n2≤1.76.

[0011] In a preferred embodiment, an air gap of 5 um is formed between the wedge prism and the right-angle prism.

[0012] In a preferred embodiment, the light-emitting element includes four light-emitting sub-units, and the light-emitting sub-units are distributed in an array.

[0013] In a preferred embodiment, the projection module includes a first lens, a second lens, a third lens, a fourth lens and a first prism which are sequentially arranged in a direction close to the display chip. The focal lengths of the first lens, the second lens, the third lens, the fourth lens and the projection module are F1, F2, F3, F4 and F respectively, and satisfy:

[0014] -1.982≤F1 / F≤-1.563, 0.566≤F2 / F≤0.657, -0.538≤F3 / F≤-0.410, 0.512≤F4 / F≤0.607.

[0015] In a preferred embodiment, the projection module includes a fifth lens, a sixth lens, a seventh lens and a second prism arranged in sequence toward the display chip; the fifth lens and the sixth lens are aspherical lenses, and a surface of the seventh lens close to the second prism is a binary surface.

[0016] The beneficial effects of the present invention are as follows: by optimizing the design of the lighting module and the projection module, the optical path complexity of the lighting module and the projection module is reduced, the energy utilization rate and illumination uniformity of the lighting module and the projection module are improved, and at the same time, the volume and weight of the near-eye display device are effectively reduced, thereby improving the user's wearing experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a modular structure of a near-eye display device provided by an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of the structure of a lighting module provided by an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of the structure of a free-form surface prism provided in an embodiment of the present invention;

[0020] Figure 4 A schematic diagram of the structure of a wedge prism and a right-angle prism provided in an embodiment of the present invention;

[0021] Figure 5 A first structural schematic diagram of a projection module provided in an embodiment of the present invention;

[0022] Figure 6 A second structural schematic diagram of a projection module provided in an embodiment of the present invention;

[0023] Figure 7 An MTF curve diagram of a first structure of a projection module provided by an embodiment of the present invention;

[0024] Figure 8 This is an MTF curve diagram of the second structure of the projection module provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In the present invention, the terms "disposed", "provided with" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0027] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] The present invention provides a near-eye display device, which is used to solve the problems that the near-eye display device is too large in size and weight, the optical path is relatively complex, and the energy utilization rate and illumination uniformity are relatively low.

[0030] Please refer to Figure 1In this embodiment, the near-eye display device includes a control system 1, an illumination system 2 and a projection system 3; the illumination system 2 includes a first driving module 21, a light-emitting element 22 and a lighting module 23; the projection system 3 includes a second driving module 31, a display chip 32 and a projection module 33; the first driving module 21 and the second driving module 31 are electrically connected to the control system 1 respectively, the light-emitting element 22 is electrically connected to the first driving module 21, the display chip 32 is electrically connected to the second driving module 31, and the display chip 32 is connected between the illumination module 23 and the projection module 33.

[0031] Among them, the control system 1 is used to output control signals for controlling the lighting system 2 and the projection system 3. The first driving module 21 is used to receive the control signal of the control system 1 to control the light-emitting element 22. The lighting module 23 is used to receive and adjust the light emitted by the light-emitting element 22, and project the output light onto the display chip 32. The second driving module 31 is used to receive the control signal of the control system 1 to control the display chip 32. The projection module 33 is used to project the image on the display chip 32 onto the image coupling area of ​​the optical waveguide. The light-emitting element 22 includes four light-emitting sub-units, and the light-emitting sub-units are distributed in an array. It is easy to understand that the array distribution structure of the four light-emitting sub-units can make the light source structure more compact and lower in cost.

[0032] The control system 1 inputs a first control signal to the first driving module 21, the first driving module 21 starts and drives the light-emitting element 22 to operate, the light-emitting element 22 outputs the corresponding light to the lighting module 23, the lighting module 23 adjusts the light and evenly irradiates the light to the display chip 32, the control system 1 inputs a second control signal to the second driving module 31, the second driving module 31 drives the display chip 32 to operate, realizes the conversion of color scale and gray scale on the display chip 32 to display the corresponding image, and outputs the corresponding image to the projection module 33, the projection module 33 projects the image input by the display chip 32 to the image coupling area of ​​the optical waveguide, which is finally received by the human eye.

[0033] For details, please refer to Figure 2 The lighting module 23 includes a free-form surface prism 231, a light homogenizer 232, a wedge-shaped prism 233 and a right-angle prism 234, which are sequentially arranged between the light-emitting element 22 and the display chip 32. The refractive index n1 of the wedge-shaped prism 233 is smaller than the refractive index n2 of the right-angle prism 234. The free-form surface prism 231 is used to collect and converge the light input from the light-emitting element 22, the light homogenizer 232 is used to adjust the uniformity of the light, and the wedge-shaped prism 233 and the right-angle prism 234 are used to separate or change the light path.

[0034] After the first driving module 21 drives the light emitting element 22 to operate, the light emitted by the light emitting element 22 first passes through the free-form surface prism 231, and the free-form surface prism 231 collects the light. After passing through the free-form surface prism 231, the light enters the light homogenizer 232, and the light homogenizer 232 focuses the light, so that the small light beams with different uniformity are superimposed and compensate each other, thereby achieving the effect of homogenization. After passing through the light homogenizer 232, the light passes through the wedge prism 233 and the right-angle prism 234 in turn, and the wedge prism 233 and the right-angle prism 234 adjust the light path, which can effectively reduce the volume of the lighting module 23 and realize the projection of light onto the display chip 32.

[0035] For further information, please refer to Figure 3 In one embodiment, the free-form surface prism 231 includes a first curved surface 2311 , a second curved surface 2312 and a third curved surface 2313 , the third curved surface 2313 is close to the light emitting element 22 , the second curved surface 2312 is far away from the light homogenizing element 232 , and the first curved surface 2311 is close to the light homogenizing element 232 .

[0036] The first curved surface 2311, the second curved surface 2312 and the third curved surface 2313 are all defined by an XY polynomial, which is obtained by superimposing Taylor polynomials on a quadratic surface. When designing the free-form surface prism 231, the light emitting element 22 can be used to perform reverse light path tracing design to obtain the desired free-form surface prism 231.

[0037] After the light emitting element 22 emits light, the light enters the free-form surface prism 231 through the third curved surface 2313, and then the light is projected onto the first curved surface 2311. The first curved surface 2311 reflects the light so that the light reaches the second curved surface 2312. The second curved surface 2312 reflects the light so that the light passes through the first curved surface 2311 and is collimated to exit the free-form surface prism 231. Specifically, in order to achieve total reflection of the light emitted by the light emitting element 22, the incident angle of the light on each curved surface must be greater than 40.8°. A reflective film with high reflectivity needs to be coated on the second curved surface 2312 so that the surface of the second curved surface 2312 can meet the Lambertian scattering, so as to ensure that after being reflected by the second curved surface 2312, the light can be collimated and emitted from the first curved surface 2311.

[0038] In a preferred embodiment, a parabola is formed on the third curved surface 2313 , the curvature radius r1 of the parabola satisfies 2.5 mm≤r1≤5 mm, and the aperture R1 of the parabola satisfies 0.9 mm≤R1≤1.5 mm.

[0039] It can be understood that the light emitted by the light-emitting component 22 enters the free-form surface prism 231 through the third curved surface 2313. Since the divergence angle of the light-emitting component 22 is relatively large, in order to allow as much light as possible to enter the free-form surface prism, a parabola with a radius r1 satisfying 2.5mm≤r1≤5mm and an aperture R1 satisfying 0.9mm≤R1≤1.5mm is formed on the third curved surface 2313, which can better focus the light emitted by the light-emitting component 22.

[0040] In a preferred embodiment, the second curved surface 2312 is a Fresnel surface, and the sawtooth depth h on the Fresnel surface satisfies 2.5 mm≤h≤5 mm.

[0041] Specifically, in order not to change the reflected light path, a reflective film is plated on the sawtooth surface on the Fresnel surface, and the direction of the sawtooth is consistent with the direction of the second curved surface 2312. The number of sawtooth on the Fresnel surface can be selected according to actual design requirements.

[0042] It can be understood that by providing a plurality of saw teeth on the Fresnel surface, the weight of the free-form surface prism 231 can be effectively reduced, thereby reducing the weight of the near-eye display device.

[0043] Furthermore, in one embodiment, the light homogenizer 232 is an array lens or a DOE element.

[0044] Specifically, when the light homogenizer 232 adopts an array lens, the light homogenizer 232 can be composed of a plurality of micro lenses, and the shape of the micro lens is related to the shape of the light spot on the image plane of the display chip 32, and a rectangular or regular polygonal shape can be adopted. In this embodiment, the shape of the micro lens is a regular hexagon with a thickness of 0.5 mm. It is easy to understand that after the light passes through the array lens, the array lens focuses the light, and the fine light beams emitted by multiple micro lenses overlap with each other, so that the fine light beams with different uniformity are superimposed, and then compensate each other, and finally achieve the effect of homogenization.

[0045] When the light homogenizer 232 uses a DOE element, while achieving the light beam shaping effect, the volume of the lighting module 23 can be better reduced, thereby reducing the volume of the near-eye display device and achieving a relatively high energy utilization rate. Specifically, the DOE element uses the first diffraction order, and the number of lines N satisfies 0.45l / um≤N≤0.6l / um.

[0046] Further, in one embodiment, the refractive index n1 of the wedge prism 233 satisfies 1.51≤n1≤1.54, and the refractive index n2 of the right-angle prism 234 satisfies 1.70≤n2≤1.76. An air gap of 5 um is formed between the wedge prism 233 and the right-angle prism 234 .

[0047] It can be understood that the refractive index n1 of the wedge prism 233 is greater than the refractive index n2 of the right-angle prism 234, and satisfies 1.51≤n1≤1.54, 1.70≤n2≤1.76, which can effectively control the propagation direction of the light, realize the deflection and focusing of the light, and effectively reduce the volume of the projection module 33, thereby reducing the volume of the near-eye display device. At the same time, a 5um air gap is formed between the wedge prism 233 and the right-angle prism 234, which can effectively prevent stray light.

[0048] For details, please refer to Figure 4 The wedge-shaped prism 233 includes a first surface ED, a second surface DC, a third surface EF and a fourth surface FC, and the right-angle prism 234 includes a fifth surface AC, a sixth surface AB and a seventh surface BC, wherein an air gap is formed between the fourth surface FC of the wedge-shaped prism 233 and the fifth surface AC of the right-angle prism 234, and the seventh surface BC is an exit surface, and light can be projected onto the display chip 32 after passing through the seventh surface BC.

[0049] The calculation process of the refractive index n1 of the wedge prism 233 and the refractive index n2 of the right angle prism 234 is as follows: After the light enters the right angle prism 234 and is refracted at the seventh surface BC, the incident angle of the outgoing light projected to the display chip 32 is marked as θ D , the law of refraction needs to satisfy the formula The light is totally reflected on the fifth surface AC of the right-angle prism 234. At this time, the light propagates from the optically dense medium to the optically sparse medium, that is, from the medium with a high refractive index to the medium with a low refractive index. c is: sin(θ c )≥n1 / n2, total reflection occurs on the incident surface, where n1 is the refractive index of the optically rarer medium and n2 is the refractive index of the optically denser medium. c The critical angle satisfies At the same time, from the geometric relationship of the triangle, we can know that: θ5=α-θ c After determining the angle α of the right angle prism 234 and the incident angle θ of the light projected onto the display chip 32 D After that, θ5 and n2 can be determined.

[0050] Specifically, in a preferred embodiment, the right-angle prism 234 is an isosceles right-angle prism 234, that is, α is 45°, and θ D After being defined as 17°, it can be determined that θ5 is 9.7° and n2 is 1.73. Then, in the same way, it can be determined that n2 satisfies 1.70≤n2≤1.76.

[0051] After n2 is determined, for the efficient illumination system 2, the refractive index n1 of the wedge prism 233 also needs to satisfy:

[0052]

[0053]

[0054]

[0055] θ5=45°-θ4

[0056] Since there is a correlation between the size of θ1 and the wedge prism 233, it is necessary to balance θ1 and As the value of θ1 increases, the aberration becomes larger, so θ1 is limited to within 30°. In order to use a wider working range of θ1, the refractive index n1 of the wedge prism 233 is smaller and needs to satisfy 1.51≤n1≤1.54.

[0057] For further information, please refer to Figure 5 In one embodiment, the projection module 33 includes a first lens 331, a second lens 332, a third lens 333, a fourth lens 334 and a first prism 335 which are sequentially arranged in a direction close to the display chip 32. The focal lengths of the first lens 331, the second lens 332, the third lens 333, the fourth lens 334 and the projection module 33 are F1, F2, F3, F4 and F respectively, and satisfy:

[0058] -1.982≤F1 / F≤-1.563, 0.566≤F2 / F≤0.657, -0.538≤F3 / F≤-0.410, 0.512≤F4 / F≤0.607.

[0059] The first lens 331, the second lens 332, the third lens 333 and the fourth lens 334 are all plastic lenses, and the first lens 331, the second lens 332, the third lens 333 and the fourth lens 334 are all aspherical lenses, specifically, 10th order aspherical lenses. The total length of the projection module 33 is 23.2 mm, and the maximum field of view is 40°.

[0060] Specifically, in a preferred embodiment, the focal length of the first lens 3311 is -13.95 mm; the focal length of the second lens 3322 is 5.144 mm; the focal length of the third lens 3333 is -3.343 mm; and the focal length of the fourth lens 3344 is 5.18 mm. The first lens 331, the second lens 332, the third lens 333 and the fourth lens 334 are all plastic lenses, which can effectively reduce the weight of the projection module 33, thereby reducing the weight of the near-eye display device.

[0061] Furthermore, the MTF value is between 0 and 1. The larger the value, the better the image quality of the optical system. Please refer to Figure 7, the MTF of the aforementioned projection module 33 is greater than 0.5 at 94p / mm in the full field of view, so the image quality of the projection module 33 meets the design requirements. It can be understood that the projection module 33 has a simpler structure and is less difficult to assemble than a traditional projection lens, which can effectively reduce the weight of the near-eye display device and has relatively better image quality.

[0062] For further information, please refer to Figure 6 In one embodiment, the projection module 33 includes a fifth lens 337, a sixth lens 338, a seventh lens 339 and a second prism 3310 which are sequentially arranged in a direction close to the display chip 32; the fifth lens 337 and the sixth lens 338 are aspherical lenses, and a surface of the seventh lens 339 close to the second prism 3310 is a binary surface.

[0063] The fifth lens 337, the sixth lens 338 and the seventh lens 339 are all plastic lenses, and the fifth lens 337 and the sixth lens 338 are all aspherical lenses, specifically, 10th order aspherical lenses. The total length of the projection module 33 is 17.9 mm, and the maximum viewing angle is 40°.

[0064] The overall optical path of the projection module 33 is an image-side telecentric optical path, and the distortion is controlled within 1%. A refraction-diffraction joint design can be adopted, which can effectively improve the vertical chromatic aberration of the projection module 33 while reducing the number of lenses. For details, please refer to Figure 8 At the cutoff frequency, the central field of view is higher than 0.5, and the edge field of view is higher than 0.4, which indicates that the projection module 33 has good projection quality in both the central field of view and the edge field of view, and the full field of view is higher than 0.8 at 50l p / mm, which indicates that the image details are significantly improved.

[0065] In summary, the present application reduces the complexity of the optical paths of the lighting module and the projection module by optimizing the design of the lighting module and the projection module, improves the energy utilization rate and illumination uniformity of the lighting module and the projection module, and effectively reduces the volume and weight of the near-eye display device, thereby improving the user's wearing experience.

[0066] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A near-eye display device, characterized in that: It includes a control system, an illumination system and a projection system; the illumination system includes a first driving module, a light-emitting element and an illumination module; the projection system includes a second driving module, a display chip and a projection module; the first driving module and the second driving module are electrically connected to the control system respectively, the light-emitting element is electrically connected to the first driving module, the display chip is electrically connected to the second driving module, the display chip is connected between the illumination module and the projection module, and the illumination module includes a free-form surface prism, a light homogenizing element, a wedge prism and a right-angle prism which are sequentially arranged between the light-emitting element and the display chip, and the refractive index n1 of the wedge prism is less than the refractive index n2 of the right-angle prism.

2. The near-eye display device according to claim 1, characterized in that: The free-form surface prism includes a first curved surface, a second curved surface and a third curved surface. The third curved surface is close to the light emitting element, the second curved surface is far away from the light homogenizing element, and the first curved surface is close to the light homogenizing element.

3. The near-eye display device according to claim 2, characterized in that: A parabola is formed on the third curved surface, a curvature radius r1 of the parabola satisfies 2.5 mm≤r1≤5 mm, and an aperture R1 of the parabola satisfies 0.9 mm≤R1≤1.5 mm.

4. The near-eye display device according to claim 2, characterized in that: The second curved surface is a Fresnel surface, and the sawtooth depth h on the Fresnel surface satisfies 2.5 mm≤h≤5 mm.

5. The near-eye display device according to claim 1, characterized in that: The light homogenizing element is an array lens or a DOE element.

6. The near-eye display device according to claim 1, characterized in that: The refractive index n1 of the wedge prism satisfies 1.51≤n1≤1.54, and the refractive index n2 of the right-angle prism satisfies 1.70≤n2≤1.

76.

7. The near-eye display device according to claim 1, characterized in that: An air gap of 5 μm is formed between the wedge-shaped prism and the right-angle prism.

8. The near-eye display device according to claim 1, characterized in that: The light-emitting element includes four light-emitting sub-units, and the light-emitting sub-units are distributed in an array.

9. The near-eye display device according to claim 1, characterized in that: The projection module includes a first lens, a second lens, a third lens, a fourth lens and a first prism which are sequentially arranged in a direction close to the display chip. The focal lengths of the first lens, the second lens, the third lens, the fourth lens and the projection module are F1, F2, F3, F4 and F respectively, and satisfy: -1.982≤F1 / F≤-1.563, 0.566≤F2 / F≤0.657, -0.538≤F3 / F≤-0.410, 0.512≤F4 / F≤0.

607.

10. The near-eye display device according to claim 1, characterized in that: The projection module includes a fifth lens, a sixth lens, a seventh lens and a second prism which are sequentially arranged toward the display chip; the fifth lens and the sixth lens are aspherical lenses, and a surface of the seventh lens close to the second prism is a binary surface.

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