Short focal length eyepiece assembly for head mounted display device

Abstract

The present invention discloses a short-focus eyepiece assembly applied to a head-mounted display device, wherein the short-focus eyepiece assembly is arranged adjacent to a display of the head-mounted display device, and the short-focus eyepiece assembly receives an image source of the display, so that the short-focus eyepiece assembly generates a focused image at its focus, wherein the short-focus eyepiece assembly includes at least two Fresnel lenses, the two Fresnel lenses are arranged adjacent to each other side by side, and the surfaces with threads on the two Fresnel lenses are arranged opposite to each other, and a fixing ring is arranged at the edges of the two lenses to fix the two Fresnel lenses and prevent dust from entering between the two Fresnel lenses. The present invention can effectively shorten the focal length of imaging through the arrangement of two Fresnel lenses, so as to achieve the purpose of reducing the volume of the eyepiece, so as to realize the application of small-sized virtual reality eyepieces.

Description

Technical Field

[0001] The present invention relates to a technology of an optical component, and in particular to a short-focal-length eyepiece component applied to a head-mounted display device. Background Art

[0002] Virtual reality (VR) is a technology that uses computer technology to generate a virtual image of a three-dimensional space and project the image into the user's eyes, making the user feel as if they are in the environment.

[0003] Currently, the technology used to realize virtual reality mostly requires users to wear a virtual reality device on their heads and place the display screen in the virtual reality device close to the user's eyes, so that the user can see the display image magnified several times at a short distance.

[0004] Please refer to Figure 1 , to illustrate the structure of a generally existing head-mounted display 90 (Head-mounted display, HMD). As shown in the figure, the head-mounted display 90 includes a shell 92, and a display screen 94 and at least one lens 96 are enclosed in the shell 92. The display screen 94 and the lens 96 can be arranged side by side in the shell 92, so that the image of the display screen 94 can be projected on the lens 96. After the display screen 94 projects the image on the lens 96, the lens 96 can adjust the focus position of the image to project the image at a close distance to the user's eyes 98, so that the user can view a wide-angle picture through the head-mounted display 90 to generate a virtual reality image.

[0005] However, the disadvantages of current virtual reality devices are that their lenses are relatively thick and the focal length of the lenses is relatively far away, so that the size and weight of the virtual reality devices cannot be effectively reduced, making the virtual reality devices quite bulky. When users wear them on their heads, the virtual reality devices may be too large or too heavy, causing discomfort when wearing them, resulting in problems such as the user being unable to wear them for a long time.

[0006] In view of this, the present invention aims at the above-mentioned deficiencies of the prior art and proposes a short focal length eyepiece assembly applied to a head mounted display device to effectively overcome the above-mentioned problems. Summary of the invention

[0007] The main purpose of the present invention is to provide a short-focal-length eyepiece assembly for a head-mounted display device, which can effectively shorten the focal length of the image by setting two Fresnel lenses, so as to reduce the volume of the eyepiece and realize the application of small-size virtual reality eyepieces.

[0008] Another object of the present invention is to provide a short-focal-length eyepiece assembly for a head-mounted display device, which can effectively shorten the focal length of the image and make the image clearer.

[0009] To achieve the above-mentioned purpose, the present invention provides a short-focus eyepiece assembly applied to a head-mounted display device. The short-focus eyepiece assembly is disposed adjacent to a display of the head-mounted display device. The short-focus eyepiece assembly can receive an image source of the display so that the short-focus eyepiece assembly produces a focused image at its focus. The short-focus eyepiece assembly includes at least two Fresnel lenses. The at least two Fresnel lenses are disposed adjacent to each other side by side, and a spacing is further provided between the at least two Fresnel lenses. The spacing can be 0.5 mm to 3 mm. The surfaces with threads on the at least two Fresnel lenses are disposed opposite to each other, and a fixing ring is disposed on the edges of the at least two lenses to fix the at least two Fresnel lenses and achieve a dustproof effect.

[0010] The short focal length eyepiece assembly meets Where F is the focal length of the short-focus eyepiece assembly, ω is the half viewing angle in the horizontal direction, and the distance between the TTL short-focus eyepiece assembly and the display.

[0011] The short focal length eyepiece assembly meets Where H is the image height corresponding to the maximum field of view (FOV), ω is the half viewing angle in the horizontal direction, and E is the distance from the aperture to the short focal length eyepiece assembly.

[0012] The short focal length eyepiece assembly meets Where f1 and f2 are the focal distances of the two Fresnel lenses.

[0013] The short focal length eyepiece assembly meets Wherein F is the focal length of the short focal length eyepiece assembly, and H is the image height corresponding to the maximum field of view (FOV).

[0014] The following detailed description is made through specific embodiments to make it easier to understand the purpose, technical content, characteristics and effects achieved by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of an existing head-mounted display architecture.

[0016] Figure 2 It is a three-dimensional schematic diagram of the short focal length eyepiece assembly structure of the present invention.

[0017] Figure 3 It is a side cross-sectional view of the short focal length eyepiece component structure of the present invention.

[0018] Figure 4 This is a schematic diagram of the architecture of the short focal length eyepiece assembly of the present invention installed in a head mounted display device.

[0019] Figure 5 This is a schematic diagram of the use state of the short-focal-length eyepiece assembly of the present invention installed on a head-mounted display device.

[0020] Explanation of the reference numerals: 1-short focal length eyepiece assembly; 10-Fresnel lens; 10'-Fresnel lens; 102-thread; 102'-thread; 104-plane; 104'-plane; 12-fixing member; 20-head-mounted display device; 22-shell; 24-display; 26-eye; a-distance; b-focus; 90-head-mounted display; 92-shell; 94-display screen; 96-lens; 98-eye. DETAILED DESCRIPTION

[0021] The present invention provides a short-focal-length eyepiece assembly, which can be installed in a head-mounted display device to adjust the image on the display of the head-mounted display device. The short-focal-length eyepiece assembly can not only make the image appear clearly, but also can effectively reduce the weight and volume of the head-mounted display device because the short-focal-length eyepiece assembly is thin and light and has a short focal length, thereby realizing the application of small-sized virtual reality eyepieces.

[0022] Please refer to Figure 2 as well as Figure 3, to illustrate the structure of the short-focus eyepiece assembly 1 of the present invention, the short-focus eyepiece assembly 1 of the present invention comprises at least two Fresnel lenses 10, 10', which are arranged side by side and adjacent to each other, wherein the Fresnel lenses 10, 10' are Fresnel lenses made of optical plastic or glass. In the present embodiment, one surface of the Fresnel lenses 10, 10' has a thread 102, 102', and the other surface with the thread is a plane 104, 104'. In the present embodiment, the surfaces of the two Fresnel lenses 10, 10' with the threads 102, 102' are arranged opposite to each other, and the two Fresnel lenses 10, 10' are further fixed together by a fixing member 12 arranged at the edges of the two Fresnel lenses 10, 10'. In the present embodiment, the fixing member 12 is an annular sleeve, which is ringed around the edges of the two Fresnel lenses 10, 10' to fix the two Fresnel lenses 10, 10' together. At the same time, the setting of the fixing member 12 can also prevent dust from entering between the two Fresnel lenses 10, 10'. Of course, the two Fresnel lenses 10, 10' are not limited to the surfaces with threads 102, 102' being arranged opposite to each other. The present invention can also make the planes 104, 104' arranged corresponding to each other, or the surface with threads 102 and the plane 104' being arranged corresponding to each other. The present invention is not limited to the above embodiment of arranging the surfaces with threads 102, 102' opposite to each other. A distance a is further provided between the two Fresnel lenses 10, 10' of the short focal length eyepiece assembly 1. The distance a can be 0.5 mm to 3 mm. The distance a is quite short and does not occupy space, which can effectively reduce the volume of the short focal length eyepiece assembly 1. Furthermore, the present invention can make the focal length of the short-focus eyepiece assembly 1 less than 25 mm by arranging two Fresnel lenses 10 and 10' side by side. Compared with the focal length of 60 mm of the conventional lens, the focal length of the short-focus eyepiece assembly 1 of the present invention is quite short. Therefore, when used in a head-mounted display device, the purpose of effectively reducing the size of the head-mounted display device can be achieved.

[0023] After describing the structure of the short focal length eyepiece assembly 1 of the present invention, please refer to Figure 4 , to illustrate an embodiment of the short focal length eyepiece assembly 1 of the present invention installed in a head mounted display device 20. As shown in the figure, the short focal length eyepiece assembly 1 of the present invention can be installed in the head mounted display device 20 to replace the existing lens in the head mounted display device in the past, thereby shortening the volume and focal length of the lens setting, so that the head mounted display device 20 can achieve the purpose of reducing the volume. Figure 4 As shown, the head-mounted display device 20 includes a shell 22, which encloses a short-focus eyepiece assembly 1 and a display 24, wherein the short-focus eyepiece assembly 1 is disposed adjacent to the display 24 of the head-mounted display device 20, and the display 24 can be a display screen, and its size can be between 1.5 inches and 2.5 inches.

[0024] Please refer to the following Figure 5 , to explain in detail the usage status of the head-mounted display device 20, the short-focus eyepiece component 1 can receive the image source emitted by the display 24, and then the short-focus eyepiece component 1 can generate a focused image at its focus b, so that the user's eyes 26 are placed at the focus position, and the user can appreciate the focused image to experience the technology of virtual reality.

[0025] Furthermore, the structure of the short focal length eyepiece assembly 1 of the present invention can satisfy the following four conditions:

[0026]

[0027] Where F is the focal length of the short-focus eyepiece assembly, ω is the half viewing angle in the horizontal direction, and the distance between the TTL short-focus eyepiece assembly and the display.

[0028]

[0029] Where H is the image height corresponding to the maximum field of view (FOV), ω is the half viewing angle in the horizontal direction, and E is the distance from the aperture to the short focal length eyepiece assembly.

[0030]

[0031] Where f1 and f2 are the focal distances of the two Fresnel lenses.

[0032]

[0033] Wherein F is the focal length of the short focal length eyepiece assembly, and H is the image height corresponding to the maximum field of view (FOV).

[0034] In order to prove that the structure of the short focal length eyepiece assembly 1 of the present invention can produce better imaging for users to watch, please refer to the following four sets of experimental data to prove that the short focal length eyepiece assembly 1 of the present invention has a good imaging effect. Under the conditions of the short focal length eyepiece assembly 1 having a focal length f=18.21, an aperture size FNO=4.5, and a half viewing angle 2ω=88.7° in the double horizontal direction, the lens parameters (Table 1) and the aspheric coefficients (Table 2) are as follows:

[0035]

[0036] Table 1. Lens parameters

[0037] Lens surface K A B C D E F G 2 infinity 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 3 -0.446658 0.000E+00 -1.276E-07 4.002E-10 -3.436E-13 0.000E+00 0.000E+00 0.000E+00 4 infinity 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 5 -0.79189 0.000E+00 1.586E-07 -4.018E-10 3.46E-13 0.00E+00 0.00E+00 0.00E+00

[0038] Table 2. Aspheric coefficients

[0039] Under the conditions of the short focal length eyepiece assembly 1 having a focal length f=20.2, an aperture size FNO=5, and a half viewing angle 2ω=89.3° in the double horizontal direction, the lens parameters (Table 3) and the aspheric coefficients (Table 4) are as follows:

[0040]

[0041] Table 3. Lens parameters

[0042] Lens surface K A B C D E F G 2 ∞ 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00E+00 0.00E+00 0.00E+00 3 1.69389625 0.000E+00 -5.302E-07 2.163E-09 -2.071E-12 0.00E+00 0.00E+00 0.00E+00 4 ∞ 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00E+00 0.00E+00 0.00E+00 5 -0.58627179 0.000E+00 6.868E-07 -2.518E-09 2.94E-12 0.00E+00 0.00E+00 0.00E+00

[0043] Table 4. Aspheric coefficients

[0044] Under the conditions of the short focal length eyepiece assembly 1 having a focal length f=20.1, an aperture size FNO=4.9, and a half viewing angle 2ω=90.1° in the double horizontal direction, the lens parameters (Table 5) and the aspheric coefficients (Table 6) are as follows:

[0045]

[0046] Table 5. Lens parameters

[0047] Lens surface K A B C D E F G 2 ∞ 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00E+00 0.00E+00 0.00E+00 3 1.1129 0.000E+00 -5.328E-08 2.193E-09 -1.257E-12 0.00E+00 0.00E+00 0.00E+00 4 ∞ 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00E+00 0.00E+00 0.00E+00 5 -0.41014 0.000E+00 6.926E-07 -2.744E-09 3.43E-12 0.00E+00 0.00E+00 0.00E+00

[0048] Table 6. Aspheric coefficients

[0049] Under the conditions of the short focal length eyepiece assembly 1 having a focal length f=22.59, an aperture size FNO=5.4, and a half viewing angle 2ω=92.8° in the double horizontal direction, the lens parameters (Table 7) and the aspheric coefficients (Table 8) are as follows:

[0050]

[0051] Table 7. Lens parameters

[0052] Lens surface K A B C D E F G 2 ∞ 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00E+00 0.00E+00 0.00E+00 3 1.8542 0.000E+00 -5.708E-07 2.395E-07 -2.109E-12 0.00E+00 0.00E+00 0.00E+00 4 ∞ 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.00E+00 0.00E+00 0.00E+00 5 -0.286717 0.000E+00 6.990E-07 -2.760E-09 3.57E-12 0.00E+00 0.00E+00 0.00E+00

[0053] Table 8. Aspheric coefficients

[0054] In summary, the short-focal-length eyepiece assembly of the present invention can effectively shorten the focal length of the image by disposing two Fresnel lenses, so as to reduce the volume of the eyepiece, and at the same time make the image clearer, so as to realize the application of small-size virtual reality eyepieces.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Therefore, all equivalent changes or modifications based on the features and spirit described in the claims of the present invention should be included in the protection scope of the present invention.

Claims

1. A short-focus eyepiece assembly for a head-mounted display device, which is disposed adjacent to a display of the head-mounted display device, the short-focus eyepiece assembly receives an image source of the display, and the short-focus eyepiece assembly generates a focused image at its focus, characterized in that: The short focal length eyepiece assembly is composed of two Fresnel lenses, which are adjacent to each other and arranged side by side; The surfaces with threads on the two Fresnel lenses are arranged opposite to each other; It further comprises a fixing member, which is annularly arranged on the edges of the two Fresnel lenses to fix the two Fresnel lenses; The short focal length eyepiece assembly meets F is the focal length of the short-focus eyepiece assembly, ω is the half viewing angle in the horizontal direction, and TTL is the distance between the short-focus eyepiece assembly and the display; The short focal length eyepiece assembly meets H represents the image height corresponding to the maximum field of view, and E represents the distance from the aperture to the short focal length eyepiece assembly.

2. The short focal length eyepiece assembly for a head mounted display device according to claim 1, wherein: There is a distance between the two Fresnel lenses, and the distance is 0.5 mm to 3 mm.

3. The short focal length eyepiece assembly for a head mounted display device according to claim 1, wherein: The short-focus eyepiece assembly has a focal length of less than 25 mm.

4. The short focal length eyepiece assembly for a head mounted display device according to claim 1, wherein: The short focal length eyepiece assembly meets The f1 and f2 are the focal lengths of the two Fresnel lenses respectively.

5. The short focal length eyepiece assembly for a head mounted display device according to claim 1, wherein: The short focal length eyepiece assembly meets F is the focal length of the short focal length eyepiece assembly, and H is the image height corresponding to the maximum field of view.

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