CN112162383A

CN112162383A - Lens, projection optical machine and near-to-eye display system

Info

Publication number: CN112162383A
Application number: CN202011097931.XA
Authority: CN
Inventors: 郑光
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2021-01-01

Abstract

The embodiment of the application provides a lens, a projection light machine and a near-eye display system, the lens can be applied to the projection light machine, the projection light machine can be applied to the near-eye display system, the lens comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged along an optical axis direction, the first lens is used for converging effective light signals emitted by a display to form first transmission light signals, the second lens is used for dispersing the first transmission light signals to form second transmission light signals, the third lens is used for dispersing the second transmission light signals to form third transmission light signals, and the fourth lens is used for converging the third transmission light signals to form fourth transmission light signals. The lens of the embodiment of the application can modulate the effective light signal emitted by the display to reduce the aberration.

Description

Lens, projection optical machine and near-to-eye display system

Technical Field

The application relates to the technical field of display projection, in particular to a lens, a projection optical machine and a near-to-eye display system.

Background

With the continuous development of augmented reality technology, head-mounted augmented reality devices such as smart glasses or smart masks are widely accepted and applied by users.

Augmented reality equipment can include projector and camera usually, and the projector can generate virtual image, and the light of virtual image and the light of real environment can shoot into simultaneously and wear the user pupil of augmented reality equipment for the user who wears augmented reality equipment not only can see real thing, can also see virtual image.

Disclosure of Invention

The embodiment of the application provides a lens, a projection optical machine and a near-to-eye display system, wherein the lens can be applied to the projection optical machine so as to modulate an effective optical signal emitted by the projection optical machine.

The embodiment of the application provides a lens, include along optical axis direction arrange first lens, second lens, third lens and the fourth lens that sets up in proper order, first lens is used for converging the effective light signal that the display was launched in order to form first transmitted light signal, the second lens is used for the dispersion first transmitted light signal is in order to form second transmitted light signal, the third lens is used for the dispersion second transmitted light signal is in order to form third transmitted light signal, the fourth lens is used for converging third transmitted light signal is in order to form fourth transmitted light signal.

The embodiment of the application provides a projection optical machine, including display and camera lens, the camera lens be like the above application embodiment the camera lens, the display is used for launching effective light signal, the display sets up one side of camera lens and with first lens is adjacent so that effective light signal can penetrate into first lens.

An embodiment of the present application provides a near-to-eye display system, including:

a display, pixel points of which emit effective optical signals having different emission angles, the effective optical signals including image information;

the lens is arranged on one side of the display and used for receiving the effective optical signal and modulating the effective optical signal so as to enable the effective optical signal generated by one pixel point to form parallel light beams with different emergent angles after passing through the lens;

and the waveguide element is arranged on one side of the lens, which is far away from the display, and is used for receiving the parallel light beams and converting the parallel light beams into a virtual image.

The camera lens of this application embodiment includes first lens, second lens, third lens and the fourth lens of arranging in proper order along the optical axis direction, and the effective light signal that the display launched passes through four lenses in proper order, and four lenses can modulate effective light signal in order to reduce the aberration.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a first structural view of a projection light engine according to an embodiment of the present disclosure.

FIG. 2 is a diagram of a modulation transfer function of a lens of the optical projection engine shown in FIG. 1.

Fig. 3 is a field curvature diagram of a lens in the optical projection engine shown in fig. 1.

FIG. 4 is a diagram illustrating a distortion curve of a lens of the optical projection engine shown in FIG. 1.

FIG. 5 is a defocus graph of the lens of the optical projection engine shown in FIG. 1.

Fig. 6 is a second structural diagram of a projection light engine according to an embodiment of the present disclosure.

FIG. 7 is a diagram illustrating a modulation transfer function of a lens of the optical projection engine shown in FIG. 6.

Fig. 8 is a field curvature diagram of the lens of the optical projection engine shown in fig. 6.

FIG. 9 is a graph showing distortion of the lens of the optical projection engine shown in FIG. 6.

FIG. 10 is a defocus graph of the lens of the optical projection engine shown in FIG. 6.

Fig. 11 is a schematic structural diagram of a near-eye display system according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The embodiment of the application provides a projection ray apparatus, which is used for generating a virtual image. As shown in fig. 1, fig. 1 is a first structural view of a projection light engine according to an embodiment of the present disclosure. The light engine 200 can project a virtual image. The optical projection engine 200 includes a display 220 and a lens 240, the lens 240 is disposed on one side of the display 220, the display 220 can emit light, wherein an optical signal for generating a virtual image is an effective optical signal, the effective optical signal can transmit through the lens 240, and the lens 240 can correct the effective optical signal to eliminate various aberrations, thereby improving the imaging quality of the virtual image to be projected by the optical projection engine 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 order along an optical axis direction (or a transmission direction of the effective optical signal), the first lens 241 being disposed adjacent to the display 220. It is understood that the first lens 241, the second lens 242, the third lens 243, and the fourth lens 244 are arranged in order from the image source side to the image side.

The first lens 241 may receive the effective light signal emitted from the display 220 and converge the effective light signal to form a first transmitted light signal, the second lens 242 may receive and disperse the first transmitted light signal to form a second transmitted light signal, the third lens 243 may receive and disperse the second transmitted light signal to form a third transmitted light signal, and the fourth lens 244 may receive and converge the third transmitted light signal to form a fourth transmitted light signal. For example, the first lens 241 is a positive power lens, which has a converging effect on the effective optical signal, and the effective optical signal can form a first transmitted optical signal after passing through the first lens 241; the second lens 242 is a negative power lens, and has a divergence effect on the effective optical signal, and the first transmission optical signal can form a second transmission optical signal after passing through the second lens 242; the third lens 243 is a cemented lens, the combined focal power of the cemented lens is a negative value, the third lens 243 has a dispersion effect on the third transmission light signal, and the second transmission light signal can form the third transmission light signal after passing through the third lens 243, so that chromatic aberration can be reduced or corrected; the fourth lens is a positive power lens, which has a converging effect on the effective optical signal, and the third transmitted optical signal can form a fourth transmitted optical signal after passing through the fourth lens 244.

The effective optical signals emitted by the microdisplay of the embodiment of the application can sequentially pass through the first lens 241, the second lens 242, the third lens 243 and the fourth lens 244, and the four lenses can modulate the effective optical signals to reduce aberration, so that the imaging effect of the virtual image projected by the projection light machine 200 is improved.

With continued reference to fig. 1, the third lens 243 may be formed by gluing two single-piece lenses. For example, the third lens 243 may 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 matched, so that one surface of the first sub-lens 2431 and one surface of the second sub-lens 2432 may be glued to each other. The first sub-lens 2431 is positioned between the second sub-lens 2432 and the second lens 242, and the first sub-lens 2431 is a negative power lens that has a diverging 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 power lens having a converging effect on the optical signal transmitted through the first sub-lens 2431.

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), where the luminance of the Micro OLED is less than 5000nits and the luminance of the LCD is less than 15000nits under the operating power condition. The display 220 in the embodiment of the present application may also be a Micro Light Emitting Diode (Micro-LED) display, for example, a green Micro-LED, or other single-color Micro-LEDs or white Light multi-color Micro-LEDs. Compared with Micro-OLED and LCD, the brightness of the Micro-LED can reach 2000000nits, which is far higher than that of the Micro-OLED and LCD. In addition, the Micro-LED is a self-luminous light source, so that the projection system matched with the Micro-LED has better contrast and better display delay.

The effective light emitting area of display 220 has a diagonal dimension of 0.17inch to 0.19inch and an aspect ratio of 1: 1. In other embodiments, or the display 220 may have an effective light emitting area diagonal size of 0.25inch to 0.29inch and an effective light emitting area aspect ratio of 16: 9. Wherein a glass cover plate is disposed outside the active light emitting surface of the display 220, and the glass cover plate can exist in a separate form or be integrally packaged in the display 220. The thickness range of the glass cover plate is 0.3mm-0.8 mm.

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 camera lens 240, four lenses of this application embodiment all adopt the glass material to make, and for the lens that the plastics material was made, the thermal stability of the lens that the glass material was made is better, is heated and is difficult to produce deformation. First lens 241, second lens 242, first sub lens 2431, second sub lens 2432 and fourth lens 244 of this application embodiment are spherical lens, adopt the scheme of glass sphere to carry out small-size optical system design, when can guarantee the optical system stability of temperature variation on a large scale, realize littleer preparation and assembly cost.

As shown in fig. 1, the first lens 241 includes a first light incident surface S11 and a first light emitting surface S12 that are opposite to each other, the first light emitting surface S12 is disposed near the second lens 242, and both the first light incident surface S11 and the first light emitting surface S12 are convex surfaces. It is understood that the first light incident surface S11 and the first light emitting surface S12 of the first lens 241 are both spherical structures, the first light incident surface S11 is a surface protruding from the image side toward the image source side, and the first light emitting surface S12 is a surface protruding from the image source side toward the image side.

The second lens 242 includes a second light incident surface S21 and a second light emitting surface S22 that are 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 is 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 concave surface facing the image side from the image source side, and the second light emitting surface S22 is a convex surface facing the image side from the image source side.

The third lens 243 includes a third light incident surface S31 and a third light emitting surface S32 that are opposite to each other, 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 is understood that the third incident surface S31 and the third light emitting surface S32 of the third lens 243 are both spherical structures, the third incident surface S31 is a concave surface facing the image side from the image source side, and the third light emitting surface S32 is a convex surface facing the image side from the image source side. The first sub-lens 2431 includes a third incident surface S31 and a first connecting surface S33 opposite to each other, the first connecting surface S33 is a concave surface, and the first connecting surface S33 is formed by being recessed from the image side toward the image source side. The second sub-lens 2432 includes a second connection surface S34 and a third light emitting surface S32, which are opposite to each other, the second connection surface S34 is connected to the first connection surface S33, the second connection surface S34 is convex, and the second connection surface S34 is formed to protrude from the image source side toward the image forming side. It should be noted that the first connection surface S33 and the second connection surface S34 are matched in size and shape, and the first connection surface S33 and the second connection surface S34 shown in fig. 1 overlap each other.

It should be noted that the structure of the third light emitting surface S32 is not limited to this, for example, the third light emitting surface S32 may also be a concave surface or a plane surface. The fourth lens 244 includes a fourth light incident surface S41 and a fourth light emitting surface S42 that are opposite to each other, the fourth light incident surface S41 is located between the third light emitting surface S32 and the fourth light emitting surface S42, the fourth light incident surface S41 may be one of a convex surface, a concave surface and a planar 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 is formed by protruding from the image forming side toward the image source side. The fourth light emitting surface S42 is convex, and the fourth light emitting surface S42 is formed to protrude from the image source side toward the image forming side.

The fourth light emitting surface S42 and the third light emitting surface S32 are both spherical structures, and a distance between a spherical vertex of the fourth light emitting surface S42 and a spherical vertex of the third light emitting surface S32 is less than 0.8mm, for example, a distance between a spherical vertex of the fourth light emitting surface S42 and a spherical vertex of the third light emitting surface S32 may be 0.8mm, 0.5mm, or 0.2 mm.

In the embodiment of the application, the first light incident surface S11 is a spherical surface structure, a distance between a spherical vertex of the first light incident surface S11 and the display 220 is less than 4mm, for example, the distance between the first light incident surface S11 and the display 220 may be 4mm, 3.5mm, 3mm, 2mm, or 1 mm. In 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 in a spherical structure, and a distance between a spherical vertex of the first light emitting surface S12 and a spherical vertex of the second light incident surface S12 is less than 1.8mm, for example, 1.8mm, 1.5mm, 1mm, or 0.5 mm.

The projector engine 200 shown in FIG. 1 satisfies: f is more than or equal to 8.8mm and less than or equal to 10.6mm, f1 is more than or equal to 4.5mm and less than or equal to 7.3mm, and f1/f is more than 0.46 and less than 0.78; -11.9mm < f2 < 6.8mm, and-1.3 < f2/f < 0.7; f3 is more than or equal to-40 mm and less than-18 mm, and f3/f is more than-3.6 and less than-1.8; f4 is more than or equal to 8mm and less than or equal to 15mm, and f4/f is more than 0.9 and less than 1.4. Wherein f is a focal length of the projector, f1 is a focal length of the first lens, f2 is a focal length of the second lens, f3 is a focal length of the third lens, and f4 is a focal length of the fourth lens.

Wherein the third lens 243 satisfies: -2.1mm < f31 < f 4.4mm, and-0.46 < f31/f < 0.24; f32 is more than or equal to 3.6mm and less than or equal to 7.1mm, and f32/f is more than 0.35 and less than 0.66. Wherein f31 is the focal length of the first sub-lens, and f32 is the focal length of the second sub-lens.

The projector engine 200 shown in FIG. 1 further satisfies: TTL < 14mm, wherein TTL (Total Track Length) is the total optical length of the projection optical machine. The projection light engine 200 satisfying the above conditions can control the size of the projection lens as a whole, which is advantageous for realizing the miniaturization of the projection lens 200. For example, the total optical length of the projection optical engine may be 11.8mm, and the size of the lens in the related art is 40mm × 18mm × 7mm, so that the projection optical engine satisfying the above conditions greatly reduces the size of the entire projection optical engine compared with the lens in the related art.

Wherein, the thickness T1 of the first lens 241 satisfies 1.0mm ≦ T1 ≦ 2.4mm, for example, the thickness of the first lens 241 may be 1.0mm, or 1.5mm, or 2.0mm, or 2.4mm, where the thickness of the first lens 241 refers to the center thickness of the first lens 241.

The thickness T2 of the second lens 242 satisfies 0.3mm ≦ T2 ≦ 1mm, for example, the thickness of the second lens 242 may be 0.3mm, or 0.5mm, or 0.8mm, or 1mm, where the thickness of the second lens 242 refers to the center thickness of the second lens 242.

The thickness T3 of the third lens 243 satisfies 1.9mm ≦ T3 ≦ 3.2mm, for example, the thickness of the third lens 243 may be 1.9mm, or 2.5mm, or 3.0mm, or 3.2mm, where the thickness of the third lens 243 refers to the center thickness of the third lens 243. Wherein, the thickness T31 of the first sub-lens 2431 satisfies 0.4mm ≦ T31 ≦ 0.8mm, for example, the thickness of the first sub-lens 2431 may be 0.4mm, 0.5mm, or 0.8mm, and the thickness of the first sub-lens 2431 refers to the center thickness of the first sub-lens 2431; the thickness T32 of the second sub-lens 2432 satisfies 1.7mm ≦ T32 ≦ 2.4mm, such as the thickness T32 of the second sub-lens 2432 may be 1.7mm, 2.0mm, or 2.4mm, and the thickness of the second sub-lens 2432 refers to the center thickness of the second sub-lens 2432.

The thickness T4 of the fourth lens 244 satisfies 0.6mm ≦ T4 ≦ 1.4mm, for example, the thickness of the fourth lens 244 may be 0.6mm, or 1.0mm, or 1.4mm, where the thickness of the fourth lens 244 refers to the center thickness of the fourth lens 244.

The embodiment of the application can effectively control the whole size of the projection light machine 200 by reasonably setting the thickness between the lenses.

The projector engine 200 shown in FIG. 1 further satisfies: tan (FOV/2)/TTL is more than 0.021mm-1, FOV is more than or equal to 25 degrees and less than or equal to 32 degrees, wherein the FOV is a diagonal field angle of the projection light machine 200, and f is a focal length of the projection light machine 200. The projector 200 satisfying the above conditions can obtain a larger angle of view to satisfy the requirement of a large depth recognition range. The exit pupil aperture of the projection light machine 200 is 3.5mm-6mm, and the maximum optical aperture is 5.4mm-8 mm. The refractive index of the first lens 241 is between 1.75 and 1.88, and the Abbe number is between 38 and 54. The refractive index of the second lens 242 is between 1.46 and 1.57, and the Abbe number is between 58 and 69. The refractive index of the first sub-lens 2431 in the third lens 243 is between 1.88 and 1.98, the abbe number is between 16 and 36, the refractive index of the second sub-lens 2432 in the third lens 243 is between 1.8 and 1.88, and the abbe number is between 26 and 36. The refractive index of the fourth lens 244 is between 1.88 and 1.98, and the Abbe number is between 16 and 36.

To further illustrate the imaging effect of the projector 200 shown in fig. 1, the parameters of the lens according to the embodiment of the present application are shown in table 1 below:

the field angle FOV in the diagonal direction is 28, the horizontal-to-vertical field 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 5 mm.

The focal length f1 of the first lens 241 is 5.9mm, 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 of the third lens 243 is-3.2 mm, the focal length f32 of the second sub-lens 2432 of the third lens 243 is 5.3mm, and the focal length f4 of the fourth lens 244 is 10.9 mm.

Referring to fig. 2 to 5, fig. 2 is a modulation transfer function diagram of a lens in the projection optics shown in fig. 1, fig. 3 is a field curvature diagram of the lens in the projection optics shown in fig. 1, fig. 4 is a distortion curve diagram of the lens in the projection optics shown in fig. 1, and fig. 5 is a defocus curve diagram of the lens in the projection optics shown in fig. 1. Fig. 2, 3, 4 and 5 each show a related parameter map of the lens 240 having the parameters shown in table 1. The Modulation Transfer Function (MTF) refers to a relationship between a Modulation degree and a line logarithm per millimeter in an image, and can be used for evaluating the imaging quality of a lens and can be embodied as the reduction capability of imaging on original object details; the field curvature diagram can represent the curvature and warping degree of an imaging surface of the lens; the distortion graph can represent the distortion degree of a lens imaging picture; the defocus curve may represent depth-of-focus information of the lens. As can be seen from fig. 2 to fig. 5, the imaging quality of the embodiment of the present application is much higher than the nyquist sampling evaluation of the system, the distortion and the field curvature are all limited to be much smaller than the range which can not be detected by human eyes, and the assembly and debugging sensitivity of the system is weaker than the precision commonly used in the current production, which is convenient for the mass production process.

As can be seen from the modulation transfer function diagram shown in fig. 2, the MTF curves of the respective fields of view have almost the same trend, and no zero point appears on the MTF curves from high frequency to low frequency, so that the information is well preserved, and a clear image can be restored by using an appropriate filter function, which indicates that the lens 240 according to the embodiment of the present application has good resolution and resolution. As can be seen from the field curvature diagram shown in fig. 3, the distance between the two curves is relatively small, which indicates that the curvature and the warp of the imaging surface of the lens 240 according to the embodiment of the present application are relatively small, and the field curvature is well corrected. As can be seen from the distortion diagram shown in fig. 4, the optical distortion amount of the lens 240 of the embodiment of the present application is controlled to be in the range of-1.0% to 1.0%, which illustrates that the degree of distortion of the image of the lens 240 of the embodiment of the present application is relatively small. As can be seen from the defocus graph shown in fig. 5, the peaks of almost all the curves are near the zero-offset vertical axis, which indicates that the defocus characteristic of the lens 240 is excellent, a larger effective depth-of-focus value range can be obtained, and the peaks of all the defocus characteristic curves are in a higher value region, so that the imaging contrast is excellent.

With reference to fig. 1, the optical projection engine 200 of the present embodiment may further include a diaphragm 260, where the diaphragm 260 is used to precisely adjust the amount of light passing through, and a lens with a larger luminous flux is required to capture a clear picture in a scene with dark light, so that the setting of the diaphragm 260 is beneficial to controlling the incident angle of the effective light signal reaching the lens 240. The diaphragm 260 is arranged on the side of the fourth lens 244 facing away from the third lens 243. Moreover, the distance between the stop 260 and the fourth lens 244 is greater than 0.6mm and less than 5mm, for example, the distance between the stop 260 and the fourth lens 244 may be 0.6mm, 1.0mm, 3mm, 5mm, or other values. The distance between the stop 260 and the fourth lens 244 is the distance from the stop 260 to the vertex of the fourth light emitting surface S42 of the fourth lens 245. The fourth lens 244 performs beam modulation, is restricted by the stop 260, and emits parallel light having a specific beam aperture. Different positions on the display 220 correspond to different fields of view emitted by the projector 200; i.e. the light emitted by different light emitting sources exits through the aperture 260 as parallel light at the respective corresponding field angle.

The diaphragm 260 includes a shielding region and a light transmission region, the shielding region is surrounded on the periphery of the light transmission region, and the light transmission region can facilitate the adjustment of the diaphragm 260 on the effective light signal transmitted through the lens 240. The light transmission region is of a circular structure and meets the following requirements: d is more than or equal to 3.5mm and less than or equal to 6mm, and D is the aperture of the light-transmitting area. For example, the light-transmitting region may be a light-transmitting circular hole, and the aperture of the circular hole may be 3.5mm, 4.0mm, 5.0mm, 6.0mm, or other values. Of course, the light-transmitting region may have other structures, such as a rectangular structure, a trapezoidal structure, and the like. The structured surface of the stop 260 may be treated as an extinction surface to prevent light rays from reflecting or refracting on the structured surface of the stop 260 and causing other light rays to be mixed into the transmitted light signal transmitted through the lens 240.

As shown in fig. 6, fig. 6 is a second structural schematic diagram of a projection light engine according to an embodiment of the present application. The light projector 400 of the embodiment of the application includes a micro display 420 and a lens 440, wherein the micro display 420 can refer to the related description of the display 220 in the above embodiments, and the description thereof is omitted here.

The lens 440 may include a first lens 441, a second lens 442, a third lens 443, and a fourth lens 444 sequentially arranged in an optical axis direction (or an effective optical signal transmission direction), the first lens 441 being disposed adjacent to the micro display 420. It is understood that the first lens 441, the second lens 442, the third lens 443, and the fourth lens 444 are arranged in order from the image source side to the image side. The first lens 441 is a positive focal power lens and has a convergence effect on effective optical signals; the second lens 442 is a negative power lens, and has a diverging effect on the effective optical signal; the third lens 443 is a cemented lens, which can reduce chromatic aberration or correct chromatic aberration; the fourth lens 444 is a positive power lens and has a converging effect on the effective optical signal.

The structures of the first lens element 441, the third lens element 443, and the fourth lens element 444 are respectively the same as the structures of the first lens element 241, the third lens element 243, and the fourth lens element 244 in the projection lens 220 shown in fig. 1, and the description of the first lens element 441, the third lens element 443, and the fourth lens element 444 refers to the description in the above embodiments, and is not repeated herein.

The structure of the second lens element 442 is different from that of the second lens element 242, the second lens element 442 includes a second light incident surface and a second light emitting surface that are opposite to each other, the second light incident surface is located between the first light emitting surface of the first lens element 441 and the second light emitting surface of the second lens element 442, the second light incident surface is a convex surface that is formed by protruding from the imaging side toward the image source side, and the second light emitting surface is a concave surface that is formed by recessing from the imaging side toward the image source side.

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 3mm, 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 1mm, 2mm 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 0.5mm, for example, may be 0.2mm, 0.3mm, or 0.5 mm.

The light engine 400 shown in FIG. 6 satisfies: f is more than or equal to 8.6mm and less than or equal to 10.4mm, f1 is more than or equal to 4.2mm and less than or equal to 7.8mm, and f1/f is more than 0.48 and less than 0.88; f2 is more than or equal to-28 mm and less than or equal to-14 mm, and f2/f is more than-3.3 and less than-1.7; f3 is more than or equal to-12 mm and less than-1.4 and less than-3.2 f 3/f; f4 is more than or equal to 3.6mm and less than or equal to 6.4mm, and f4/f is more than 0.32 and less than 0.72;

where f is the focal length of the projection optical system 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.

Wherein the third lens 443 satisfies: -2.1mm ≤ f31 ≤ 4.2mm, and-0.42 < f31/f ≤ 0.21; f32 is more than or equal to 3.6mm and less than or equal to 6.4mm, and f32/f is more than 0.32 and less than 0.72. Wherein f31 is the focal length of the first sub-lens, and f32 is the focal length of the second sub-lens.

The light engine 400 shown in FIG. 6 further satisfies: TTL < 13mm, wherein TTL (Total Track Length) is the total optical length of the projection optical machine. The projection optical system 400 satisfying the above conditions can control the size of the projection lens as a whole, which is advantageous for realizing the miniaturization of the projection lens 400. For example, the total optical length of the projection optical engine may be 10.9mm, and the size of the lens in the related art is 40mm × 18mm × 7mm, so that the projection optical engine satisfying the above conditions greatly reduces the overall size of the projection optical engine compared with the lens in the related art.

The thickness T1 of the first lens 441 satisfies 1.0mm ≦ T1 ≦ 1.9mm, for example, the thickness of the first lens 241 may be 1.0mm, or 1.4mm, or 1.9mm, where the thickness of the first lens 441 refers to the center thickness of the first lens 441.

The thickness T2 of the second lens 442 satisfies 0.5mm ≦ T2 ≦ 1mm, for example, the thickness of the second lens 442 may be 0.5mm, or 0.8mm, or 1mm, where the thickness of the second lens 442 refers to the center thickness of the second lens 442.

The thickness T3 of the third lens 443 satisfies 1.9mm < T3 < 4.1mm, for example, the thickness of the third lens 443 can be 1.9mm, or 2.4mm, or 4.1mm, where the thickness of the third lens 443 refers to the center thickness of the third lens 443. Wherein, the thickness T31 of the first sub-lens 4431 satisfies 0.5mm ≦ T31 ≦ 0.8mm, for example, the thickness of the first sub-lens 4431 may be 0.5mm, 0.6mm, or 0.8mm, 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 1.4mm ≦ T32 ≦ 2.3mm, for example, the thickness T32 of the second sub-lens 4432 may be 1.4mm, 1.8mm, or 2.3mm, and the thickness of the second sub-lens 432 refers to the center thickness of the second sub-lens 4432.

The thickness T4 of the fourth lens 444 satisfies 0.6mm ≦ T4 ≦ 1.4mm, for example, the thickness of the fourth lens 444 may be 0.6mm, or 1.0mm, or 1.4mm, where the thickness of the fourth lens 444 refers to the center thickness of the fourth lens 444.

The embodiment of the application can effectively control the whole size of the projection light machine 400 by reasonably setting the thickness between the lenses.

The light engine 400 shown in FIG. 6 further satisfies: tan (FOV/2)/TTL is more than 0.021mm-1, FOV is more than or equal to 25 degrees and less than or equal to 32 degrees, wherein the FOV is a diagonal field angle of the projection light machine 400, and f is a focal length of the projection light machine 400. The projection optical machine 400 satisfying the above conditions can obtain a larger angle of view to satisfy the requirement of a large depth recognition range. The exit pupil aperture of the projection light engine 400 is 3.5mm to 6mm, and the maximum optical aperture is 5.4mm to 8 mm.

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, 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.

To further illustrate the imaging effect of the projection optical device 400 shown in fig. 2, the parameters of the lens according to the embodiment of the present application are shown in table 2 below:

the field angle in the diagonal direction is that the FOV is 28 degrees, the horizontal to vertical field ratio is 1:1, the total optical length TTL of the lens 440 is 10.9mm, the focal length f of the lens 440 is 9.1mm, the maximum optical aperture D is 5.8mm, and the exit pupil aperture is 5 mm. In the embodiment of the present application, the Micro display 420 employs a green Micro-LED having an effective light emitting area of 0.26 inch, and an effective light emitting area of 3.24mm × 3.24mm is used.

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

Referring to fig. 7 to 10, fig. 7 is a modulation transfer function diagram of a lens in the projection optics shown in fig. 6, fig. 8 is a field curvature diagram of the lens in the projection optics shown in fig. 6, fig. 9 is a distortion curve diagram of the lens in the projection optics shown in fig. 6, and fig. 10 is a defocus curve diagram of the lens in the projection optics shown in fig. 6. Fig. 7, 8, 9, and 10 each show a related parameter map for a lens 440 having parameters as shown in table 2. As can be seen from fig. 7 to fig. 10, the imaging quality of the embodiment of the present application is much higher than the nyquist sampling evaluation of the system, the distortion and the field curvature are all limited to be much smaller than the range which can not be detected by human eyes, and the assembly and debugging sensitivity of the system is weaker than the precision commonly used in the current production, which is convenient for the mass production process.

As can be seen from the modulation transfer function diagram shown in fig. 2, the MTF curves of the respective fields of view have almost the same trend, and no zero point appears on the MTF curves from high frequency to low frequency, so that the information is well preserved, and a clear image can be restored by using an appropriate filter function, which indicates that the lens 240 according to the embodiment of the present application has good resolution and resolution. As can be seen from the field curvature diagram shown in fig. 3, the distance between the two curves is relatively small, which indicates that the curvature and the warp of the imaging surface of the lens 240 according to the embodiment of the present application are relatively small, and the field curvature is well corrected. As can be seen from the distortion diagram shown in fig. 4, the optical distortion amount of the lens 240 of the embodiment of the present application is controlled to be in the range of-2.0% to 2.0%, which illustrates that the degree of distortion of the image of the lens 240 of the embodiment of the present application is relatively small. As can be seen from the defocus graph shown in fig. 5, the peaks of almost all the curves are near the zero-offset vertical axis, which indicates that the defocus characteristic of the lens 240 is excellent, a larger effective depth-of-focus value range can be obtained, and the peaks of all the defocus characteristic curves are in a higher value region, so that the imaging contrast is excellent.

An embodiment of the present application further provides a near-eye display system, such as shown in fig. 11, where fig. 11 is a schematic structural diagram of the near-eye display system provided in the embodiment of the present application. The near-eye display system 20 may include the light projector 200 (which may also be the light projector 400) as described above, and a waveguide element 600, the waveguide element 600 being disposed on a side of the lens 240 facing away from the display 220. As shown in fig. 1, the display 22 has pixel points, each of the pixel points can emit effective optical signals with different emission angles, the effective optical signals can include image information, and the lens can receive the effective optical signals with different emission angles and modulate the effective optical signals, so that the effective optical signals generated by one of the pixel points form parallel light beams with different exit angles after passing through the lens 230.

It can be understood that the lens 240 may be disposed between the display 220 and the waveguide 600, the lens 240 is located on one side of the emergent light of the display 220, the lens 240 may modulate the effective light signals emitted by the display 220, so that all the effective light signals entering the lens 240 are modulated into a specific light signal state to be output, where the light signals entering the lens 240 are light beams with a certain divergence angle emitted by an array formed by pixels at different positions on the light emitting surface of the display 220, the light signals output after passing through the lens 240 are parallel light beams overlapping at the outer exit pupil position of the lens 220 and corresponding to different exit angles of different pixels, and the set of different exit angles corresponding to all the pixels is the field of view of the near-to-eye display system formed by the display 220 and the lens 240. The waveguide 600 may convert the optical signal emitted from the lens 240 into a virtual image after the optical signal is coupled in, propagated by total internal reflection, and coupled out, and transmit the virtual image to human eyes, so that the human eyes can watch the virtual image. . It should be noted that the positional relationship between the light projector 200 and the waveguide 600 in fig. 11 is only an example, and the positional relationship between the light projector 200 and the waveguide 600 in fig. 11 is not limited to a parallel arrangement, and may also be set at an inclined angle, such as 45 degrees, 60 degrees or other angle values.

The lens, the projector and the near-to-eye display system provided by the embodiment of the present application are described in detail above. The principles and implementations of the present application are described herein using specific examples, which are presented only to aid in understanding the present application. Meanwhile, for those skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. A lens is characterized by comprising a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged along the direction of an optical axis, wherein the first lens is used for converging an effective light signal emitted by a display to form a first transmission light signal, the second lens is used for dispersing the first transmission light signal to form a second transmission light signal, the third lens is used for dispersing the second transmission light signal to form a third transmission light signal, and the fourth lens is used for converging the third transmission light signal to form a fourth transmission light signal.

2. The lens barrel as claimed in claim 1, the first lens being a positive power lens, the second lens being a negative power lens, the third lens being a cemented lens and the combined power of the cemented lens being a negative value, the fourth lens being a positive power lens.

3. The lens barrel according to claim 2, wherein the third lens includes a first sub lens and a second sub lens cemented with each other, the first sub lens being located between the second sub lens and the second lens and the first sub lens being a negative power lens, the second sub lens being located between the first sub lens and the fourth lens and the second sub lens being a positive power lens.

4. The lens barrel according to claim 3, wherein the first sub-lens comprises an incident surface and a first cemented surface which are opposite to each other, the incident surface faces the third lens and is a concave surface, and the cemented surface is a concave surface;

the second sub-lens comprises a second adhesive surface and an emergent surface which are arranged in a reverse manner, the second adhesive surface is connected with the first adhesive surface, the second adhesive surface is a convex surface, the shape of the second adhesive surface is matched with that of the first adhesive surface, the emergent surface faces the fourth lens, and the emergent surface is a convex surface;

the second optical signal enters from the incident surface, sequentially passes through the first bonding surface and the second bonding surface, and exits from the exit surface to form the third optical signal.

5. The lens barrel according to any one of claims 1 to 4, wherein the first lens includes a first light incident surface and a first light emitting surface that are opposite to each other, the first light emitting surface is disposed near 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 in a back-to-back manner, the second light incident surface is positioned 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 is including the third income plain noodles and the third play plain noodles that set up back to back, the third income plain noodles is located the third lens with between the third goes out the plain noodles, the third goes into plain noodles and is one of convex surface, concave surface and planar structure, the third goes out the plain noodles and is the convex surface.

6. A lens barrel according to any one of claims 1 to 4, wherein the lens barrel satisfies: TTL is less than 14mm, wherein TTL is the total optical length of the lens.

7. The lens barrel according to claim 6, wherein the exit pupil diameter of the lens barrel is 3.5mm to 6mm, and the maximum optical diameter of the lens barrel is 5.4mm to 8 mm.

8. The lens barrel according to claim 6, wherein the lens barrel satisfies: tan (FOV/2)/TTL >0.021mm^-1The FOV is more than or equal to 25 degrees and less than or equal to 32 degrees, wherein the FOV is the field angle of the lens in the diagonal direction.

9. A lens barrel according to any one of claims 1 to 4, wherein the total optical length of the lens barrel is less than 14mm, and the lens barrel satisfies: t1 is more than or equal to 1.0mm and less than or equal to 2.4mm, T2 is more than or equal to 0.3mm and less than or equal to 1mm, T3 is more than or equal to 1.9mm and less than or equal to 3.2mm, and T4 is more than or equal to 0.6mm and less than or equal to 1.4 mm;

wherein T1 is a thickness of the first lens, T2 is a thickness of the second lens, T3 is a thickness of the third lens, and T4 is a thickness of the fourth lens.

10. The lens barrel according to claim 9, wherein a distance between the first lens and the second lens is greater than 1.8mm, and a distance between the third lens and the fourth lens is less than 0.8 mm.

11. The lens barrel according to claim 9, wherein a distance between the first lens and the second lens is less than 0.5mm, and a distance between the third lens and the fourth lens is less than 0.8 mm.

12. The lens barrel according to claim 9, wherein: the lens satisfies: f is more than or equal to 8.6mm and less than or equal to 10.4mm, f1 is more than or equal to 4.2mm and less than or equal to 7.8mm, and f1/f is more than 0.48 and less than 0.88; f2 is more than or equal to-28 mm and less than or equal to-14 mm, and f2/f is more than-3.3 and less than-1.7; f3 is more than or equal to-12 mm and less than-1.4 and less than-3.2 f 3/f; f4 is more than or equal to 3.6mm and less than or equal to 6.4mm, and f4/f is more than 0.32 and less than 0.72;

wherein 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.

13. The lens barrel according to any one of claims 1 to 4, wherein the first lens, the second lens, the third lens and the fourth lens are made of a glass material.

14. A projection optical machine, comprising a display and a lens, wherein the lens is the lens of any one of claims 1 to 13, the display is used for emitting an effective optical signal, and the display is disposed at one side of the lens and adjacent to the first lens so that the effective optical signal can enter the first lens.

15. The light engine of claim 14, further comprising a diaphragm disposed on a side of the fourth lens facing away from the third lens, wherein the diaphragm is disposed coaxially with the lens, a distance between the diaphragm and the lens is greater than 0.6mm and less than 5mm, and the diaphragm is configured to modulate the fourth transmission light signal such that the transmission light signals transmitted through the diaphragm are parallel to each other.

16. The optical system according to claim 15, wherein the diaphragm comprises a shielding region and a light-transmitting region, the shielding region is arranged around the periphery of the light-transmitting region, the light-transmitting region is of a circular structure, and the light-transmitting region satisfies the following conditions: d is more than or equal to 3.5mm and less than or equal to 6mm, and D is the aperture of the light-transmitting area.

17. A near-eye display system, comprising:

18. The near-eye display system of claim 17 wherein the lens comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the optical axis, the first lens is disposed adjacent to the display such that the effective light signal generated by each of the pixel points can be incident on the first lens, the first lens is configured to converge the effective light signal generated by each of the pixel points to form a first transmitted light signal at a plurality of different exit angles, the second lens is configured to converge the plurality of first transmitted light signals to form a second transmitted light signal at a plurality of different exit angles, the third lens is configured to disperse the plurality of second transmitted light signals to form a third transmitted light signal at a plurality of different exit angles, and the fourth lens is configured to disperse the third transmitted light signal to form a fourth transmitted light signal at a plurality of different exit angles, a plurality of fourth transmitted light signals corresponding to one of the pixel points are parallel to each other.

19. The near-eye display system of claim 18 wherein the total optical length of the lens is less than 14mm, and the lens satisfies: t1 is more than or equal to 1.0mm and less than or equal to 2.4mm, T2 is more than or equal to 0.3mm and less than or equal to 1mm, T3 is more than or equal to 1.9mm and less than or equal to 3.2mm, and T4 is more than or equal to 0.6mm and less than or equal to 1.4 mm;

20. The near-eye display system of claim 19 wherein the distance between the display and the first lens is less than 4mm, the distance between the first and second lenses is greater than 1.8mm, and the distance between the third and fourth lenses is less than 0.8 mm.