Lens, projection engine, and near-eye display system

Abstract

The embodiment of the present application provides a lens, a projection optical machine and a near-eye display system. The lens can be applied to the projection optical machine, and the projection optical machine can be applied to the near-eye display system. The lens includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the optical axis direction. The first lens is used to converge the effective light signal emitted by the display to form a first transmitted light signal, the second lens is used to disperse the first transmitted light signal to form a second transmitted light signal, the third lens is used to disperse the second transmitted light signal to form a third transmitted light signal, and the fourth lens is used to converge the third transmitted light signal to form a fourth transmitted light signal. The lens of the embodiment of the present application can modulate the effective light signal emitted by the display to reduce aberrations.

Description

Technical Field

[0001] The present application relates to the field of display projection technology, and in particular to a lens, a projection optical machine, and a near-eye display system. Background Art

[0002] With the continuous development of augmented reality technology, head-mounted augmented reality devices such as smart glasses or smart masks have been widely accepted and used by users.

[0003] An augmented reality device may generally include a projector and a camera. The projector may generate a virtual image. The light of the virtual image and the light of the real environment may simultaneously enter the pupil of a user wearing the augmented reality device, so that the user wearing the augmented reality device can not only see real objects but also virtual images. Summary of the invention

[0004] The embodiments of the present application provide a lens, a projection optical machine, and a near-eye display system. The lens can be applied to the projection optical machine to modulate the effective light signal emitted by the projection optical machine.

[0005] An embodiment of the present application provides a lens, comprising a first lens, a second lens, a third lens and a fourth lens arranged in sequence along an optical axis direction, wherein the first lens is used to converge an effective light signal emitted by a display to form a first transmitted light signal, the second lens is used to disperse the first transmitted light signal to form a second transmitted light signal, the third lens is used to disperse the second transmitted light signal to form a third transmitted light signal, and the fourth lens is used to converge the third transmitted light signal to form a fourth transmitted light signal.

[0006] An embodiment of the present application provides a projection optical machine, including a display and a lens, wherein the lens is the lens as described in the above embodiment of the application, and the display is used to emit a valid light signal. The display is arranged on one side of the lens and adjacent to the first lens so that the valid light signal can be injected into the first lens.

[0007] The embodiment of the present application provides a near-eye display system, including:

[0008] A display, wherein pixels of the display emit effective light signals with different emission angles, and the effective light signals include image information;

[0009] A lens, arranged at one side of the display, for receiving the effective light signal and modulating the effective light signal, so that the effective light signal generated by one pixel point forms parallel light beams with different emission angles after passing through the lens;

[0010] A waveguide element is arranged on a side of the lens away from the display, and the waveguide element is used to receive the parallel light beams and convert the parallel light beams into a virtual image.

[0011] The lens of the embodiment of the present application includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the optical axis direction. The effective light signal emitted by the display passes through the four lenses in sequence. The four lenses can modulate the effective light signal to reduce aberrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0013] Figure 1 The first structural intention of the projection optical machine provided in the embodiment of the present application.

[0014] Figure 2 for Figure 1 The modulation transfer function diagram of the lens in the projection optical machine shown.

[0015] Figure 3 for Figure 1 Field curvature diagram of the lens in the projection optical machine shown.

[0016] Figure 4 for Figure 1 The distortion curve of the lens in the projection optical machine shown.

[0017] Figure 5 for Figure 1 The defocus curve of the lens in the projection optical machine shown.

[0018] Figure 6 A second structural schematic diagram of the projection optical machine provided in an embodiment of the present application.

[0019] Figure 7 for Figure 6 The modulation transfer function diagram of the lens in the projection optical machine shown.

[0020] Figure 8 for Figure 6 Field curvature diagram of the lens in the projection optical machine shown.

[0021] Fig. 9 for Figure 6 The distortion curve of the lens in the projection optical machine shown.

[0022] Fig.10 for Figure 6 The defocus curve of the lens in the projection optical machine shown.

[0023] Fig.11 A schematic diagram of the structure of a near-eye display system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0025] The embodiment of the present application provides a projection optical machine, which is used to generate a virtual image. Figure 1 As shown, Figure 1 The first structural intention of the projection optical machine provided in the embodiment of the present application. The projection optical machine 200 can project a virtual image. The projection optical machine 200 includes a display 220 and a lens 240, the lens 240 is arranged on one side of the display 220, and the display 220 can emit light, wherein the light signal for generating the virtual image is an effective light signal, and the effective light signal can be transmitted through the lens 240, and the lens 240 can correct the effective light signal to eliminate various aberrations, thereby improving the imaging quality of the virtual image to be projected by the projection optical machine 200. The lens 240 may include a first lens 241, a second lens 242, a third lens 243 and a fourth lens 244 arranged in sequence along the optical axis direction (or the transmission direction of the effective light signal), and the first lens 241 is arranged adjacent to the display 220. It can be understood that the first lens 241, the second lens 242, the third lens 243 and the fourth lens 244 are arranged in sequence from the image source side to the imaging side.

[0026] Among them, the first lens 241 can receive the effective light signal emitted by the display 220 and converge the effective light signal to form a first transmitted light signal, the second lens 242 can receive and disperse the first transmitted light signal to form a second transmitted light signal, the third lens 243 can receive and disperse the second transmitted light signal to form a third transmitted light signal, and the fourth lens 244 can receive and converge the third transmitted light signal to form a fourth transmitted light signal. For example, the first lens 241 is a positive optical power lens, which has a converging effect on the effective light signal. The effective light signal can form a first transmitted light signal after passing through the first lens 241; the second lens 242 is a negative optical power lens, which has a diverging effect on the effective light signal. The first transmitted light signal can form a second transmitted light signal after passing through the second lens 242; the third lens 243 is a cemented lens and the combined optical power of the cemented lens is a negative value. The third lens 243 has a dispersing effect on the third transmitted light signal. The second transmitted light signal can form a third transmitted light signal after passing through the third lens 243, which can reduce or correct chromatic aberration; the fourth lens is a positive optical power lens, which has a converging effect on the effective light signal. The third transmitted light signal can form a fourth transmitted light signal after passing through the fourth lens 244.

[0027] The effective light signal emitted by the micro display of the embodiment of the present application can pass through the first lens 241, the second lens 242, the third lens 243 and the fourth lens 244 in sequence. The four lenses can modulate the effective light signal to reduce the aberration, thereby improving the imaging effect of the virtual image projected by the projection optical machine 200.

[0028] Please continue reading Figure 1 , the third lens 243 can be formed by gluing two single lenses. For example, the third lens 243 can include a first sub-lens 2431 and a second sub-lens 2432, and one surface of the first sub-lens 2431 and one surface of the second sub-lens 2432 are adapted to each other, so that one surface of the first sub-lens 2431 and one surface of the second sub-lens 2432 can be glued together. The first sub-lens 2431 is located between the second sub-lens 2432 and the second lens 242, and the first sub-lens 2431 is a negative optical focal length lens, which has a divergent effect on the second transmitted light signal. The second sub-lens 2432 is located between the first sub-lens 2431 and the fourth lens 244, and the second sub-lens 2432 is a positive optical focal length lens, which has a converging effect on the light signal transmitted through the first sub-lens 2431.

[0029] The display 220 in the embodiment of the present application may be a micro display, for example, the display 220 may be an organic light-emitting diode (OLED) display or a micro liquid crystal display (LCD). Under working power conditions, the brightness of the Micro-OLED is less than 5000 nits, and the brightness of the LCD is less than 15000 nits. The display 220 in the embodiment of the present application may also be a micro light-emitting diode (Micro Light Emitting Diode, Micro-LED) display, for example, it may be a green light Micro-LED, or other monochrome Micro-LED or white light complex color Micro-LED. Compared with Micro-OLED and LCD, the brightness of Micro-LED can reach 2000000 nits, which is much higher than Micro-OLED and LCD. In addition, since Micro-LED is a self-luminous light source, the projection system with Micro-LED has better contrast and better display delay.

[0030] The diagonal size of the effective light-emitting area of ​​the display 220 is 0.17 inches to 0.19 inches, and the length-to-width ratio of the effective light-emitting area is 1:1. In some other embodiments, the diagonal size of the effective light-emitting area of ​​the display 220 is 0.25 inches to 0.29 inches, and the length-to-width ratio of the effective light-emitting area is 16:9. A glass cover is provided outside the effective light-emitting surface of the display 220, and the glass cover can exist in an independent form or in the form of being integrated and packaged in the display 220. The thickness of the glass cover ranges from 0.3 mm to 0.8 mm.

[0031] The display 220 generates heat during operation, and the heat generated by the display 220 is conducted to the lens 240. In order to improve the thermal stability of the lens 240, the four lenses in the embodiment of the present application are all made of glass. Compared with lenses made of plastic, lenses made of glass have better thermal stability and are not easily deformed by heat. The first lens 241, the second lens 242, the first sub-lens 2431, the second sub-lens 2432 and the fourth lens 244 in the embodiment of the present application are all spherical lenses. The use of a glass spherical surface solution for small-size optical system design can ensure the stability of the optical system over a wide range of temperature changes while achieving lower production and assembly costs.

[0032] like Figure 1As shown, the first lens 241 includes a first light incident surface S11 and a first light emitting surface S12 which are arranged opposite to each other, the first light emitting surface S12 is arranged close to the second lens 242, and both the first light incident surface S11 and the first light emitting surface S12 are convex surfaces. It can be understood that both the first light incident surface S11 and the first light emitting surface S12 of the first lens 241 are spherical structures, and the first light incident surface S11 is a surface convex from the imaging side toward the image source side, and the first light emitting surface S12 is a surface convex from the image source side toward the imaging side.

[0033] The second lens 242 includes a second light incident surface S21 and a second light emitting surface S22 that are arranged opposite to each other, the second light incident surface S21 is located between the first light emitting surface S12 and the second light emitting surface S22, the second light incident surface S21 is a concave surface, and the second light emitting surface S22 is a convex surface. It can be understood that the second light incident surface S21 and the second light emitting surface S22 of the second lens 242 are both spherical structures, the second light incident surface S21 is a surface that is concave from the image source side toward the imaging side, and the second light emitting surface S22 is a surface that is convex from the image source side toward the imaging side.

[0034] The third lens 243 includes a third light incident surface S31 and a third light emitting surface S32 which are arranged in opposite directions. The third light incident surface S31 is located between the second light emitting surface S22 and the third light emitting surface S32. The third light incident surface S31 is a concave surface, and the third light emitting surface S32 is a convex surface. It can be understood that the third light incident surface S31 and the third light emitting surface S32 of the third lens 243 are both spherical structures. The third light incident surface S31 is a surface that is concave from the image source side toward the imaging side, and the third light emitting surface S32 is a surface that is convex from the image source side toward the imaging side. Among them, the first sub-lens 2431 includes a third light incident surface S31 and a first connecting surface S33 which are arranged in opposite directions. The first connecting surface S33 is a concave surface, and the first connecting surface S33 is formed by being concave in the direction from the imaging side toward the image source side. The second sub-lens 2432 includes a second connecting surface S34 and a third light emitting surface S32 which are arranged opposite to each other. The second connecting surface S34 is connected to the first connecting surface S33. The second connecting surface S34 is a convex surface, and the second connecting surface S34 is formed by protruding from the image source side toward the imaging side. It should be noted that the size and shape of the first connecting surface S33 and the second connecting surface S34 are adapted to each other. Figure 1 The first connecting surface S33 and the second connecting surface S34 are shown overlapping each other.

[0035] It should be noted that the structure of the third light emitting surface S32 is not limited thereto, for example, the third light emitting surface S32 may also be a concave surface or a plane. The fourth lens 244 includes a fourth light incident surface S41 and a fourth light emitting surface S42 that are disposed opposite to each other, the fourth light incident surface S41 being located between the third light emitting surface S32 and the fourth light emitting surface S42, the fourth light incident surface S41 being a convex surface, a concave surface, and a plane structure, for example, the fourth light incident surface S41 may be a convex surface, and the fourth light incident surface S41 is a structure that protrudes from the imaging side toward the image source side. The fourth light emitting surface S42 is a convex surface, and the fourth light emitting surface S42 is a structure that protrudes from the image source side toward the imaging side.

[0036] Among them, the fourth light-emitting surface S42 and the third light-emitting surface S32 are both spherical structures, and the distance between the spherical vertex of the fourth light-emitting surface S42 and the spherical vertex of the third light-emitting surface S32 is less than 0.8 mm. For example, the distance between the spherical vertex of the fourth light-emitting surface S42 and the spherical vertex of the third light-emitting surface S32 can be 0.8 mm, 0.5 mm or 0.2 mm, etc.

[0037] In the embodiment of the present application, the first light incident surface S11 is a spherical structure, and the distance between the spherical vertex of the first light incident surface S11 and the display 220 is less than 4 mm, for example, the distance between the first light incident surface S11 and the display 220 can be 4 mm, 3.5 mm, 3 mm, 2 mm, or 1 mm. In some other embodiments, the distance between the spherical vertex of the first light incident surface S11 and the display 220 is less than 3 mm. The first light emitting surface S12 and the second light incident surface S12 are both spherical structures, and the distance between the spherical vertex of the first light emitting surface S12 and the spherical vertex of the second light incident surface S12 is less than 1.8 mm, for example, 1.8 mm, 1.5 mm, 1 mm, or 0.5 mm.

[0038] like Figure 1 The projection optical machine 200 shown satisfies: 8.8mm≤f≤10.6mm, 4.5mm≤f1≤7.3mm, and 0.46<f1 / f<0.78; -11.9mm≤f2≤-6.8mm, and -1.3<f2 / f<-0.7; -40mm≤f3≤-18mm, and -3.6<f3 / f<-1.8; 8mm≤f4≤15mm, and 0.9<f4 / f<1.4. Wherein, f is the focal length of the projection optical machine, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

[0039] The third lens 243 satisfies: -2.1 mm ≤ f31 ≤ -4.4 mm, and -0.46 < f31 / f < -0.24; 3.6 mm ≤ f32 ≤ 7.1 mm, and 0.35 < f32 / f < 0.66. Where f31 is the focal length of the first sub-lens, and f32 is the focal length of the second sub-lens.

[0040] like Figure 1 The projector 200 shown also satisfies: TTL<14mm, where TTL (Total Track Length) is the total optical length of the projector. The projector 200 that satisfies the above conditions can control the size of the projection lens as a whole, which is conducive to miniaturization of the projection lens 200. For example, the total optical length of the projector can be 11.8mm, and the lens size in the related art is 40mm×18mm×7mm. The projector that satisfies the above conditions greatly reduces the overall size of the projector compared to the lens in the related art.

[0041] The thickness T1 of the first lens 241 satisfies 1.0 mm≤T1≤2.4 mm. For example, the thickness of the first lens 241 may be 1.0 mm, or 1.5 mm, or 2.0 mm, or 2.4 mm, wherein the thickness of the first lens 241 refers to the central thickness of the first lens 241 .

[0042] The thickness T2 of the second lens 242 satisfies 0.3 mm≤T2≤1 mm. For example, the thickness of the second lens 242 may be 0.3 mm, or 0.5 mm, or 0.8 mm, or 1 mm, where the thickness of the second lens 242 refers to the central thickness of the second lens 242 .

[0043] The thickness T3 of the third lens 243 satisfies 1.9 mm ≤ T3 ≤ 3.2 mm, for example, the thickness of the third lens 243 may be 1.9 mm, or 2.5 mm, or 3.0 mm, or 3.2 mm, wherein the thickness of the third lens 243 refers to the central thickness of the third lens 243. The thickness T31 of the first sub-lens 2431 satisfies 0.4 mm ≤ T31 ≤ 0.8 mm, for example, the thickness of the first sub-lens 2431 may be 0.4 mm, 0.5 mm, or 0.8 mm, and the thickness of the first sub-lens 2431 refers to the central thickness of the first sub-lens 2431; the thickness T32 of the second sub-lens 2432 satisfies 1.7 mm ≤ T32 ≤ 2.4 mm, for example, the thickness T32 of the second sub-lens 2432 may be 1.7 mm, 2.0 mm, or 2.4 mm, and the thickness of the second sub-lens 2432 refers to the central thickness of the second sub-lens 2432.

[0044] The thickness T4 of the fourth lens 244 satisfies 0.6 mm≤T4≤1.4 mm. For example, the thickness of the fourth lens 244 may be 0.6 mm, or 1.0 mm, or 1.4 mm, where the thickness of the fourth lens 244 refers to the central thickness of the fourth lens 244 .

[0045] The embodiment of the present application can effectively control the overall size of the projection optical machine 200 by reasonably setting the thickness between each lens.

[0046] like Figure 1 The projector optical engine 200 shown also satisfies: tan(FOV / 2) / TTL>0.021mm-1, 25°≤FOV≤32°, where FOV is the diagonal field of view of the projector optical engine 200, and f is the focal length of the projector optical engine 200. The projector optical engine 200 that meets the above conditions can obtain a larger field of view to meet the needs of a large depth recognition range. The exit pupil diameter of the projector optical engine 200 is 3.5mm-6mm, and the maximum optical aperture is 5.4mm-8mm. Among them, the refractive index of the first lens 241 is between 1.75-1.88, and the Abbe number is between 38-54. The refractive index of the second lens 242 is between 1.46-1.57, and the Abbe number is between 58-69. The refractive index of the first sub-lens 2431 in the third lens 243 is between 1.88-1.98, and the Abbe number is between 16-36. The refractive index of the second sub-lens 2432 in the third lens 243 is between 1.8-1.88, and the Abbe number is between 26-36. The refractive index of the fourth lens 244 is between 1.88-1.98, and the Abbe number is between 16-36.

[0047] To further explain Figure 1 The imaging effect of the projection optical machine 200 shown in the figure, the parameters of the lens of the embodiment of the present application are shown in the following Table 1:

[0048]

[0049] Among them, the diagonal field of view FOV is 28, the horizontal and vertical field of view ratio is 1:1, the total optical length TTL of the lens 240 is 11.8mm, the focal length f of the lens 240 is 9.4mm, the maximum optical aperture D is 6.8mm, and the exit pupil aperture is 5mm.

[0050] The focal length f1 of the first lens 241 is 5.9 mm, the focal length f2 of the second lens 242 is -9.4 mm, the focal length f3 of the third lens 243 is -26 mm, the focal length f31 of the first sub-lens 2431 in the third lens 243 is -3.2 mm, the focal length f32 of the second sub-lens 2432 in the third lens 243 is 5.3 mm, and the focal length f4 of the fourth lens 244 is 10.9 mm.

[0051] Please refer to Figures 2 to 5, Figure 2 for Figure 1 The modulation transfer function diagram of the lens in the projection optical machine shown in the figure, Figure 3 for Figure 1 The field curvature diagram of the lens in the projection optical machine shown, Figure 4 for Figure 1 The distortion curve of the lens in the projection optical machine shown in the figure is Figure 5 for Figure 1 The defocus curve of the lens in the projection optical machine shown. Figure 2 , Figure 3 , Figure 4 and Figure 5 1 and 2 show the relevant parameter diagrams of the lens 240 with the parameters shown in Table 1. Among them, the modulation transfer function (MTF) refers to the relationship between the modulation degree and the number of line pairs per millimeter in the image, which can be used to evaluate the imaging quality of the lens, and can be reflected in the ability of the imaging to restore the details of the original object; the field curvature diagram can show the curvature and warping of the imaging surface of the lens; the distortion diagram can show the degree of deformation of the lens imaging picture; the defocus curve can show the focal depth information of the lens. Figures 2 to 5 It can be seen that the imaging quality of the embodiment of the present application is far higher than the Nyquist sampling evaluation of the system, the distortion and field curvature are limited to a range far smaller than that which cannot be detected by the human eye, and the assembly and debugging sensitivity of the system is weaker than the accuracy commonly used in current production, which is convenient for mass production process.

[0052] from Figure 2 It can be seen from the modulation transfer function diagram shown that the MTF curves of each field of view have almost the same variation trend, and the MTF curves have no zero points from high frequency to low frequency, and the information is well preserved and can be restored to a clear image using an appropriate filter function, indicating that the lens 240 of the embodiment of the present application has good resolution and resolution capability. Figure 3 It can be seen from the field curvature diagram that the distance between the two curves is relatively small, indicating that the curvature and warping of the imaging surface of the lens 240 of the embodiment of the present application are relatively small, and the field curvature is well corrected. Figure 4 It can be seen from the distortion diagram that the optical distortion of the lens 240 of the embodiment of the present application is controlled within the range of -1.0% to 1.0%, indicating that the degree of deformation of the imaging image of the lens 240 of the embodiment of the present application is relatively small. Figure 5 It can be seen from the defocus curve diagram shown that the peak values ​​of almost all curves are near the zero offset vertical axis, indicating that the defocus characteristic of lens 240 is excellent, and a larger effective focal depth value range can be obtained, and the peak values ​​of all defocus characteristic curves are in a higher value area, and the imaging contrast is excellent.

[0053] Please continue reading Figure 1The projection optical machine 200 of the embodiment of the present application may also include an aperture 260. The function of the aperture 260 is to accurately adjust the amount of light passing through. In order to take a clear picture in a dark scene, a lens with a larger light flux is required. Therefore, by setting the aperture 260, it is helpful to control the incident angle of the effective light signal reaching the lens 240. The aperture 260 is set on the side of the fourth lens 244 away from the third lens 243. Moreover, the distance between the aperture 260 and the fourth lens 244 is greater than 0.6mm and less than 5mm. For example, the distance between the aperture 260 and the fourth lens 244 can be 0.6mm, 1.0mm, 3mm, 5mm or other numerical distances. Among them, the distance between the aperture 260 and the fourth lens 244 refers to the distance from the aperture 260 to the vertex of the fourth light exit surface S42 of the fourth lens 245. After the fourth lens 244 modulates the light beam, it is limited by the aperture 260 and emitted in the form of parallel light of a specific beam aperture. Different positions on the display 220 correspond to different viewing fields emitted by the projection light engine 200 ; that is, light emitted by different light sources is emitted through the aperture 260 as parallel light with respective corresponding viewing angles.

[0054] The aperture 260 includes a blocking area and a light-transmitting area. The blocking area is arranged around the periphery of the light-transmitting area. The light-transmitting area can facilitate the aperture 260 to adjust the effective light signal passing through the lens 240. The light-transmitting area is a circular structure, and the light-transmitting area satisfies: 3.5mm≤D≤6mm, where D is the aperture of the light-transmitting area. For example, the light-transmitting area can be a light-transmitting circular hole, and the aperture of the circular hole can be 3.5mm, 4.0mm, 5.0mm, 6.0mm or other values. Of course, the light-transmitting area can also be other structures, such as the light-transmitting area can be a rectangular structure, a trapezoidal structure, etc. The structural surface of the aperture 260 can be processed into a matte surface, which can prevent light from being reflected or refracted on the structural surface of the aperture 260, thereby preventing other light from being mixed into the transmitted light signal passing through the lens 240.

[0055] like Figure 6 As shown, Figure 6 The second structural diagram of the projection optical engine provided in the embodiment of the present application. The projection optical engine 400 in the embodiment of the present application includes a micro display 420 and a lens 440, wherein the micro display 420 can refer to the relevant description of the display 220 in the above embodiment, which will not be repeated here.

[0056] The lens 440 may include a first lens 441, a second lens 442, a third lens 443 and a fourth lens 444 arranged in sequence along the optical axis direction (or the effective light signal transmission direction), and the first lens 441 is arranged adjacent to the micro display 420. It can be understood that the first lens 441, the second lens 442, the third lens 443 and the fourth lens 444 are arranged in sequence from the image source side to the imaging side. Among them, the first lens 441 is a positive focal lens, which has a converging effect on the effective light signal; the second lens 442 is a negative focal lens, which has a diverging effect on the effective light signal; the third lens 443 is a cemented lens, which can reduce or correct chromatic aberration; the fourth lens 444 is a positive focal lens, which has a converging effect on the effective light signal.

[0057] The structures of the first lens 441, the third lens 443 and the fourth lens 444 are respectively Figure 1 The first lens 241, the third lens 243 and the fourth lens 244 in the projection lens 220 have the same structure. For the related description of the first lens 441, the third lens 443 and the fourth lens 444, please refer to the description in the above embodiment, which will not be repeated here.

[0058] The structure of the second lens 442 is different from that of the second lens 242. The second lens 442 includes a second light incident surface and a second light emitting surface which are arranged back to back. The second light incident surface is located between the first light emitting surface of the first lens 441 and the second light emitting surface of the second lens 442. The second light incident surface is a convex surface which protrudes from the imaging side toward the image source side, and the second light emitting surface is a concave surface which is recessed from the imaging side toward the image source side.

[0059] The distance between the spherical vertex of the first light incident surface of the first lens 441 and the micro display 420 is less than 3 mm, for example, the distance between the spherical vertex of the first light incident surface of the first lens 441 and the micro display 420 may be 1 mm, 2 mm or 3 mm. The distance between the spherical vertex of the first light emitting surface of the first lens 441 and the spherical vertex of the second light incident surface of the second lens 442 is less than 0.5 mm, for example, it may be 0.2 mm, 0.3 mm or 0.5 mm.

[0060] like Figure 6 The projection optical machine 400 shown satisfies: 8.6mm≤f≤10.4mm, 4.2mm≤f1≤7.8mm, and 0.48<f1 / f<0.88; -28mm≤f2≤-14mm, and -3.3<f2 / f<-1.7; -28mm≤f3≤-12mm, and -3.2<f3 / f<-1.4; 3.6mm≤f4≤6.4mm, and 0.32<f4 / f<0.72;

[0061] Among them, f is the focal length of the projection optical machine 400 , f1 is the focal length of the first lens 441 , f2 is the focal length of the second lens 442 , f3 is the focal length of the third lens 443 , and f4 is the focal length of the fourth lens 444 .

[0062] The third lens 443 satisfies: -2.1 mm ≤ f31 ≤ -4.2 mm, and -0.42 < f31 / f < -0.21; 3.6 mm ≤ f32 ≤ 6.4 mm, and 0.32 < f32 / f < 0.72. f31 is the focal length of the first sub-lens, and f32 is the focal length of the second sub-lens.

[0063] like Figure 6 The projector 400 shown also satisfies: TTL<13mm, where TTL (Total Track Length) is the total optical length of the projector. The projector 400 that satisfies the above conditions can control the size of the projection lens as a whole, which is conducive to miniaturization of the projection lens 400. For example, the total optical length of the projector can be 10.9mm, and the size of the lens in the related art is 40mm×18mm×7mm. The projector that satisfies the above conditions greatly reduces the size of the entire projector compared to the lens in the related art.

[0064] The thickness T1 of the first lens 441 satisfies 1.0 mm≤T1≤1.9 mm. For example, the thickness of the first lens 441 may be 1.0 mm, or 1.4 mm, or 1.9 mm. The thickness of the first lens 441 refers to the center thickness of the first lens 441 .

[0065] The thickness T2 of the second lens 442 satisfies 0.5 mm≤T2≤1 mm. For example, the thickness of the second lens 442 may be 0.5 mm, or 0.8 mm, or 1 mm, where the thickness of the second lens 442 refers to the central thickness of the second lens 442 .

[0066] The thickness T3 of the third lens 443 satisfies 1.9 mm ≤ T3 ≤ 4.1 mm, for example, the thickness of the third lens 443 may be 1.9 mm, or 2.4 mm, or 4.1 mm, wherein the thickness of the third lens 443 refers to the center thickness of the third lens 443. The thickness T31 of the first sub-lens 4431 satisfies 0.5 mm ≤ T31 ≤ 0.8 mm, for example, the thickness of the first sub-lens 4431 may be 0.5 mm, 0.6 mm, or 0.8 mm, and the thickness of the first sub-lens 4431 refers to the center thickness of the first sub-lens 4431; the thickness T32 of the second sub-lens 4432 satisfies 1.4 mm ≤ T32 ≤ 2.3 mm, for example, the thickness T32 of the second sub-lens 4432 may be 1.4 mm, 1.8 mm, or 2.3 mm, and the thickness of the second sub-lens 432 refers to the center thickness of the second sub-lens 4432.

[0067] The thickness T4 of the fourth lens 444 satisfies 0.6 mm≤T4≤1.4 mm. For example, the thickness of the fourth lens 444 may be 0.6 mm, or 1.0 mm, or 1.4 mm, where the thickness of the fourth lens 444 refers to the central thickness of the fourth lens 444 .

[0068] The embodiment of the present application can effectively control the overall size of the projection optical machine 400 by reasonably setting the thickness between each lens.

[0069] like Figure 6 The projector 400 shown also satisfies: tan(FOV / 2) / TTL>0.021mm-1, 25°≤FOV≤32°, where FOV is the diagonal field of view of the projector 400, and f is the focal length of the projector 400. The projector 400 that meets the above conditions can obtain a larger field of view to meet the requirements of a large depth recognition range. The exit pupil diameter of the projector 400 is 3.5mm-6mm, and the maximum optical diameter is 5.4mm-8mm.

[0070] The refractive index of the first lens 441 is between 1.8 and 1.9, and the Abbe number is between 32 and 50. The refractive index of the second lens 442 is between 1.46 and 1.57, and the Abbe number is between 52 and 64. The refractive index of the first sub-lens 2431 in the third lens 443 is between 1.78 and 1.94, and the Abbe number is between 16 and 36. The refractive index of the second sub-lens 2432 in the third lens 443 is between 1.74 and 1.89, and the Abbe number is between 36 and 52. The refractive index of the fourth lens 444 is between 1.82 and 1.92, and the Abbe number is between 24 and 36.

[0071] To further explain Figure 2 The imaging effect of the projection optical machine 400 shown in the figure, the parameters of the lens of the embodiment of the present application are shown in the following Table 2:

[0072]

[0073]

[0074] The diagonal field of view is 28°, the horizontal and vertical field of view ratio is 1:1, the total optical length TTL of the lens 440 is 10.9 mm, the focal length f of the lens 440 is 9.1 mm, the maximum optical aperture D is 5.8 mm, and the exit pupil diameter is 5 mm. In the embodiment of the present application, the micro display 420 uses a green light Micro-LED with an effective light emitting area of ​​0.26 inches, and uses an effective light emitting area of ​​3.24 mm×3.24 mm.

[0075] In the embodiment of the present application, the focal length f1 of the first lens 441 is 6 mm, the focal length f2 of the second lens 442 is -20 mm, the focal length f3 of the third lens 443 is -21 mm, the f31 of the first sub-lens 4431 in the third lens 443 is -2.8 mm, the focal length f32 of the second sub-lens 4432 in the third lens 443 is 4.7 mm, and the focal length f4 of the fourth lens is 11.4 mm.

[0076] Please refer to Figures 7 to 10 , Figure 7 for Figure 6 The modulation transfer function diagram of the lens in the projection optical machine shown in the figure, Figure 8 for Figure 6 The field curvature diagram of the lens in the projection optical machine shown, Fig. 9 for Figure 6 The distortion curve of the lens in the projection optical machine shown in the figure is Fig.10 for Figure 6 The defocus curve of the lens in the projection optical machine shown. Figure 7 , Figure 8 , Fig. 9 and Fig.10 4 and 5 show the relevant parameter diagrams of the lens 440 having the parameters shown in Table 2. Figures 7 to 10 It can be seen that the imaging quality of the embodiment of the present application is far higher than the Nyquist sampling evaluation of the system, the distortion and field curvature are limited to a range far smaller than that which cannot be detected by the human eye, and the assembly and debugging sensitivity of the system is weaker than the accuracy commonly used in current production, which is convenient for mass production process.

[0077] from Figure 2 It can be seen from the modulation transfer function diagram shown that the MTF curves of each field of view have almost the same variation trend, and the MTF curves have no zero points from high frequency to low frequency, and the information is well preserved and can be restored to a clear image using an appropriate filter function, indicating that the lens 240 of the embodiment of the present application has good resolution and resolution capability. Figure 3It can be seen from the field curvature diagram that the distance between the two curves is relatively small, indicating that the curvature and warping of the imaging surface of the lens 240 of the embodiment of the present application are relatively small, and the field curvature is well corrected. Figure 4 It can be seen from the distortion diagram that the optical distortion of the lens 240 of the embodiment of the present application is controlled within the range of -2.0% to 2.0%, indicating that the degree of deformation of the imaging image of the lens 240 of the embodiment of the present application is relatively small. Figure 5 It can be seen from the defocus curve diagram shown that the peak values ​​of almost all curves are near the zero offset vertical axis, indicating that the defocus characteristic of lens 240 is excellent, and a larger effective focal depth value range can be obtained, and the peak values ​​of all defocus characteristic curves are in a higher value area, and the imaging contrast is excellent.

[0078] The present application also provides a near-eye display system, such as Fig.11 As shown, Fig.11 The schematic diagram of the structure of the near-eye display system provided in the embodiment of the present application. The near-eye display system 20 may include the projection optical machine 200 (or the projection optical machine 400) as described above, and the waveguide element 600, which is arranged on the side of the lens 240 away from the display 220. Figure 1 As shown, the display 22 has pixels, each of which can emit effective light signals at different emission angles. The effective light signals may include image information. The lens can receive effective light signals at different emission angles and modulate the effective light signals so that the effective light signal generated by a pixel forms parallel light beams with different emission angles after passing through the lens 230.

[0079] It can be understood that the lens 240 can be set between the display 220 and the waveguide element 600. The lens 240 is located on the side of the output light of the display 220. The lens 240 can modulate the effective light signal emitted by the display 220, so that all the effective light signals entering the lens 240 are modulated into a specific light signal state output, wherein the light signal entering the lens 240 is a light beam with a certain divergence angle emitted by an array composed of pixel points at different positions on the light-emitting surface of the display 220. The light signal output after passing through the lens 240 is a parallel light beam that overlaps at the exit pupil position outside the lens 220, and different pixel points correspond to different exit angles. The set of different exit angles corresponding to all pixel points is the field of view of the near-eye display system composed of the display 220 and the lens 240. The waveguide element 600 can convert the light signal emitted by the lens 240 into a virtual image after coupling in, internal total reflection propagation, and coupling out, and transmit it to the human eye, so that the human eye can see the virtual image. . It should be noted that Fig.11 The positional relationship between the projection optical machine 200 and the waveguide element 600 is only exemplary. Fig.11The projection optical machine 200 and the waveguide element 600 are not limited to being arranged in parallel, and may be arranged at a certain angle, such as 45 degrees, 60 degrees or other angle values.

[0080] The lens, projection optical machine and near-eye display system provided in the embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A lens, characterized in that: The display device is composed of a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the optical axis direction, wherein the first lens is used to converge the effective light signal emitted by the display to form a first transmission light signal, the second lens is used to disperse the first transmission light signal to form a second transmission light signal, the third lens is used to disperse the second transmission light signal to form a third transmission light signal, and the fourth lens is used to converge the third transmission light signal to form a fourth transmission light signal; The lens satisfies: TTL<14mm, where TTL is the total optical length of the lens; tan(FOV / 2) / TTL>0.021mm -1 , 25°≤FOV≤32°, where FOV is the diagonal field of view of the lens.

2. The lens according to claim 1, wherein the first lens is a positive power lens, the second lens is a negative power lens, the third lens is a cemented lens and the combined power of the cemented lens is negative, and the fourth lens is a positive power lens.

3. The lens according to claim 2, characterized in that: The third lens includes a first sub-lens and a second sub-lens glued together, the first sub-lens is located between the second sub-lens and the second lens and is a negative power lens, the second sub-lens is located between the first sub-lens and the fourth lens and is a positive power lens.

4. The lens according to claim 3, characterized in that: The first sub-lens comprises an incident surface and a first bonding surface which are arranged opposite to each other, the incident surface faces the third lens and is a concave surface, and the bonding surface is a concave surface; The second sub-lens comprises a second bonding surface and an exit surface which are arranged opposite to each other, the second bonding surface is connected to the first bonding surface, the second bonding surface is a convex surface and the shape of the second bonding surface matches the shape of the first bonding surface, the exit surface faces the fourth lens, and the exit surface is a convex surface; The second transmitted light signal is incident from the incident surface, passes through the first gluing surface and the second gluing surface in sequence, and is emitted from the exit surface to form the third transmitted light signal.

5. The lens according to any one of claims 1 to 4, characterized in that: The first lens comprises a first light incident surface and a first light emitting surface which are arranged opposite to each other, the first light emitting surface is arranged close to the second lens, and both the first light incident surface and the first light emitting surface are convex surfaces; The second lens comprises a second light incident surface and a second light emitting surface which are arranged opposite to each other, the second light incident surface is located between the first light emitting surface and the second light emitting surface, the second light incident surface is a concave surface, and the second light emitting surface is a convex surface; The fourth lens includes a third light incident surface and a third light emitting surface arranged back to back, the third light incident surface is located between the third lens and the third light emitting surface, the third light incident surface is one of a convex surface, a concave surface and a planar structure, and the third light emitting surface is a convex surface.

6. The lens according to any one of claims 1 to 4, characterized in that: The exit pupil diameter of the lens is 3.5mm-6mm, and the maximum optical diameter of the lens is 5.4mm-8mm.

7. The lens according to any one of claims 1 to 4, characterized in that: The lens meets the following requirements: 1.0mm≤T1≤2.4mm, 0.3mm≤T2≤1mm, 1.9mm≤T3≤3.2mm, 0.6mm≤T4≤1.4mm; Wherein, T1 is the thickness of the first lens, T2 is the thickness of the second lens, T3 is the thickness of the third lens, and T4 is the thickness of the fourth lens.

8. The lens according to claim 7, characterized in that: The distance between the first lens and the second lens is greater than 1.8 mm, and the distance between the third lens and the fourth lens is less than 0.8 mm.

9. The lens according to claim 7, characterized in that: The distance between the first lens and the second lens is less than 0.5 mm, and the distance between the third lens and the fourth lens is less than 0.8 mm.

10. The lens according to claim 7, characterized in that: The lens satisfies: 8.6mm≤f≤10.4mm, 4.2mm≤f1≤7.8mm, and 0.48<f1 / f<0.88; -28mm≤f2≤-14mm, and -3.3<f2 / f<-1.7; -28mm≤f3≤-12mm, and -3.2<f3 / f<-1.4; 3.6mm≤f4≤6.4mm, and 0.32<f4 / f<0.72; Among them, f is the focal length of the lens, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

11. The lens according to any one of claims 1 to 4, characterized in that: The first lens, the second lens, the third lens and the fourth lens are all made of glass.

12. A projection optical machine, characterized in that: The invention comprises a display and a lens, wherein the lens is the lens according to any one of claims 1 to 11, the display is used to emit an effective light signal, and the display is arranged on one side of the lens and adjacent to the first lens so that the effective light signal can be injected into the first lens.

13. The projection optical machine according to claim 12, characterized in that: The projection optical machine also includes an aperture, which is arranged on the side of the fourth lens away from the third lens and is coaxial with the lens. The distance between the aperture and the lens is greater than 0.6 mm and less than 5 mm. The aperture is used to modulate the fourth transmitted light signal so that the transmitted light signals passing through the aperture are parallel to each other.

14. The projection optical machine according to claim 13, characterized in that: The aperture includes a blocking area and a light-transmitting area. The blocking area is arranged around the periphery of the light-transmitting area. The light-transmitting area is a circular structure. The light-transmitting area satisfies: 3.5mm≤D≤6mm, where D is the aperture of the light-transmitting area.

15. A near-eye display system, characterized in that: include: A display, wherein pixels of the display emit effective light signals with different emission angles, and the effective light signals include image information; A lens is arranged at one side of the display, and is composed of a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the optical axis direction, wherein the first lens is used to converge the effective light signal emitted by the display to form a first transmitted light signal, the second lens is used to disperse the first transmitted light signal to form a second transmitted light signal, the third lens is used to disperse the second transmitted light signal to form a third transmitted light signal, and the fourth lens is used to converge the third transmitted light signal to form a fourth transmitted light signal; the lens satisfies: TTL<14mm, where TTL is the total optical length of the lens; tan(FOV / 2) / TTL>0.021mm -1 , 25°≤FOV≤32°, where FOV is the diagonal field of view of the lens; The waveguide element is arranged on a side of the lens away from the display, and is used for receiving parallel light beams and converting the parallel light beams into virtual images.

16. The near-eye display system according to claim 15, characterized in that: The first lens is disposed adjacent to the display so that an effective light signal generated by each pixel point can be projected into the first lens, and a plurality of fourth transmission light signals corresponding to one pixel point are parallel to each other.

17. The near-eye display system according to claim 16, characterized in that: The lens meets the following requirements: 1.0mm≤T1≤2.4mm, 0.3mm≤T2≤1mm, 1.9mm≤T3≤3.2mm, 0.6mm≤T4≤1.4mm; Wherein, T1 is the thickness of the first lens, T2 is the thickness of the second lens, T3 is the thickness of the third lens, and T4 is the thickness of the fourth lens.

18. The near-eye display system according to claim 17, characterized in that: The distance between the display and the first lens is less than 4 mm, the distance between the first lens and the second lens is greater than 1.8 mm, and the distance between the third lens and the fourth lens is less than 0.8 mm.

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