Color light machine

Abstract

The utility model discloses a color light machine, which comprises a display image source, a first imaging lens unit, a second imaging lens unit, a third imaging lens unit and a fourth imaging lens unit which are sequentially arranged along an optical axis, each imaging lens unit comprises at least one lens, and the display image source is used for emitting color light and meets the following conditions: 5 < = f1 < = 15; 10 < = f2 < = 20; -10 < = f3 < =-2; 5 < = f4 < = 15; 5 < = f < = 15; wherein f1-f4 are the focal lengths of the first imaging lens unit, the second imaging lens unit, the third imaging lens unit and the fourth imaging lens unit in sequence, f is the focal length of the color light machine, and the unit is mm. The optical machine has higher image quality and larger FOV while ensuring miniaturization and light weight, so that the whole AR glasses field has a good color effect and is close to a glasses form, and the wearing comfort and experience of a user are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical machines, and particularly relates to a color optical machine. Background Technique

[0002] With the increasingly wide application of AR products in augmented reality, the corresponding technologies are also constantly developing. AR products are getting more and more attention and are expected to replace mobile phones as the next-generation mobile terminals. In recent years, augmented reality (AR) technology has been applied and developed rapidly in smart wearable devices. Its core component is the optical module. The field of view (FOV), thickness, and display effect of the optical module will directly determine the quality of smart wearable devices. In particular, achieving excellent image quality while having a large FOV and being thin and light has become the key to restricting the development of AR technology.

[0003] In current AR solutions, the mass-produced solutions that can present relatively good image quality are geometric solutions such as Birdbath, which have a thickness of 18 - 20 mm. Their thickness is difficult to meet the needs of people's daily wearing, and their shape is not very similar to glasses, and the light transmittance to the outside world is relatively low. Although the thin and light waveguide solution is becoming increasingly mature, it is still a great challenge to make AR glasses look like ordinary prescription glasses. The most important thing is to have a small, thin, and high-image-quality optical machine. Especially with the maturity of full-color screens and waveguide solutions, it is becoming more and more important to design a miniaturized color optical machine that matches them. Content of the Utility Model

[0004] The purpose of the utility model is to propose a color optical machine aiming at the above problems, which has a high image quality and a large FOV while ensuring miniaturization and light weight, making the entire AR glasses field approach the form of glasses while having a good color effect, so as to improve the comfort and experience of users wearing.

[0005] To achieve the above purpose, the technical solutions adopted by the utility model are as follows:

[0006] A color optical machine proposed by the utility model includes a display image source, a first imaging lens unit, a second imaging lens unit, a third imaging lens unit, and a fourth imaging lens unit arranged in sequence along the optical axis. Each imaging lens unit includes at least one lens. The display image source is used to emit color light, and the color optical machine satisfies the following conditions:

[0007] 5 ≤ f1 ≤ 15; 10 ≤ f2 ≤ 20; -10 ≤ f3 ≤ -2; 5 ≤ f4 ≤ 15; 5 ≤ f ≤ 15;

[0008] Among them, f1 is the focal length of the first imaging lens unit, f2 is the focal length of the second imaging lens unit, f3 is the focal length of the third imaging lens unit, f4 is the focal length of the fourth imaging lens unit, and f is the focal length of the color optical engine, with the unit of mm.

[0009] Preferably, the color optical engine also satisfies the following conditions:

[0010] -20 ≤ C11 ≤ -6; 5 ≤ C12 ≤ 20; 1 ≤ C21 ≤ 8; 5 ≤ C22 ≤ 20;

[0011] 2 ≤ C31 ≤ 15; 2 ≤ C32 ≤ 15; -25 ≤ C41 ≤ -6; 10 ≤ C42 ≤ 30;

[0012] Among them, C11 is the radius of curvature of the incident light surface of the first imaging lens unit, C12 is the radius of curvature of the outgoing light surface of the first imaging lens unit, C21 is the radius of curvature of the incident light surface of the second imaging lens unit, C22 is the radius of curvature of the outgoing light surface of the second imaging lens unit, C31 is the radius of curvature of the incident light surface of the third imaging lens unit, C32 is the radius of curvature of the outgoing light surface of the third imaging lens unit, C41 is the radius of curvature of the incident light surface of the fourth imaging lens unit, and C42 is the radius of curvature of the outgoing light surface of the fourth imaging lens unit, with the unit of mm.

[0013] Preferably, the color optical engine also satisfies the following conditions:

[0014] 0.5 ≤ d1 ≤ 3.0; 0.3 ≤ d2 ≤ 2.0; 0.5 ≤ d3 ≤ 3.0; 0.3 ≤ d4 ≤ 2.0;

[0015] 0.3 ≤ D1 ≤ 2.0; 0.15 ≤ D2 ≤ 2.0; 0.15 ≤ D3 ≤ 2.0; 0.15 ≤ D4 ≤ 2.0;

[0016] Among them, d1 is the thickness of the first imaging lens unit, d2 is the thickness of the second imaging lens unit, d3 is the thickness of the third imaging lens unit, d4 is the thickness of the fourth imaging lens unit, D1 is the air gap between the first imaging lens unit and the display image source, D2 is the air gap between the second imaging lens unit and the first imaging lens unit, D3 is the air gap between the third imaging lens unit and the second imaging lens unit, and D4 is the air gap between the fourth imaging lens unit and the third imaging lens unit, with the unit of mm.

[0017] Preferably, the first imaging lens unit includes a first lens, and the incident light surface of the first lens is convex and the outgoing light surface is convex; the second imaging lens unit includes a second lens, and the incident light surface of the second lens is concave and the outgoing light surface is convex; the third imaging lens unit includes a third lens, and the incident light surface of the third lens is concave and the outgoing light surface is convex; the fourth imaging lens unit includes a fourth lens, and the incident light surface of the fourth lens is convex and the outgoing light surface is convex.

[0018] Preferably, the color optical engine further satisfies the following conditions:

[0019] 1.5 ≤ n1 ≤ 1.8; 30 ≤ Vd1 ≤ 60; 1.5 ≤ n2 ≤ 1.8; 30 ≤ Vd2 ≤ 60;

[0020] 1.6 ≤ n3 ≤ 1.9; 10 ≤ Vd3 ≤ 40; 1.5 ≤ n4 ≤ 1.8; 40 ≤ Vd4 ≤ 70;

[0021] Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, Vd1 is the Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, and Vd4 is the Abbe number of the fourth lens.

[0022] Preferably, the color optical engine further includes a diaphragm, the diaphragm is located on the outgoing light side of the fourth imaging lens unit, and satisfies the following conditions:

[0023] -0.5 ≤ D5 ≤ 0.5;

[0024] Wherein, D5 is the air gap between the diaphragm and the fourth imaging lens unit, in mm.

[0025] Preferably, the surface type of each lens is one of spherical surface, aspherical surface, freeform surface, Fresnel surface, and plane.

[0026] Preferably, the aspherical surface is an even-order aspherical surface type and satisfies the following formula:

[0027]

[0028] Wherein, z is the sagittal height, Y is the lens center height, k is the conic coefficient, C is the curvature, a i is the i-th aspherical coefficient, and N is a positive integer.

[0029] Preferably, an anti-reflection film is provided on both the incident light surface and the outgoing light surface of each lens, and an ink layer is also coated on the outer edge of each lens. The outermost lens of the fourth imaging lens unit is a glass lens.

[0030] Preferably, the display image source is a Micro OLED display or a Micro LED display.

[0031] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0032] The volumes of existing color light engines are very large. Especially for those using DLP displays or LCOS displays, their power consumptions are relatively high and the contrast ratios are very poor. The color light engine of this application can adopt as few as four lenses and by using Micro LED displays or Micro OLED displays, its volume and weight are much smaller than those of existing light engines, and it has low power consumption and high contrast ratio, meeting the usage requirements for color scenarios. Moreover, by reasonably designing optical parameters (including focal length, thickness, air gap, radius of curvature, refractive index, Abbe number, etc.), while ensuring miniaturization and light weight, it has high image quality, a large FOV, and small chromatic aberration, meeting the usage requirements for matching with waveguides and the color requirements of color light engines, making the entire AR glasses field approach the form of glasses while having a good color effect, greatly improving the comfort and experience of users when wearing. In addition, the outermost lens is made of glass material, having an anti-scratch function, which helps to further improve the service life and ensure the imaging quality. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the color light engine of the present utility model;

[0034] Figure 2 It is the MTF diagram of Embodiment 1 of the present utility model;

[0035] Figure 3 It is the spot diagram of Embodiment 1 of the present utility model;

[0036] Figure 4 It is the MTF diagram of Embodiment 2 of the present utility model;

[0037] Figure 5 It is the spot diagram of Embodiment 2 of the present utility model.

[0038] Description of the reference numerals: 1. Display image source; 2. First imaging lens unit; 3. Second imaging lens unit; 4. Third imaging lens unit; 5. Fourth imaging lens unit; 6. Diaphragm. Detailed Embodiments

[0039] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a 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 of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0040] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present application. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0041] As Figures 1-5 shown, a color optical engine includes a display image source 1, a first imaging lens unit 2, a second imaging lens unit 3, a third imaging lens unit 4, and a fourth imaging lens unit 5 arranged in sequence along the optical axis. Each imaging lens unit includes at least one lens. The display image source 1 is used to emit color light, and the color optical engine satisfies the following conditions:

[0042] 5 ≤ f1 ≤ 15; 10 ≤ f2 ≤ 20; -10 ≤ f3 ≤ -2; 5 ≤ f4 ≤ 15; 5 ≤ f ≤ 15;

[0043] wherein, f1 is the focal length of the first imaging lens unit 2, f2 is the focal length of the second imaging lens unit 3, f3 is the focal length of the third imaging lens unit 4, f4 is the focal length of the fourth imaging lens unit 5, and f is the focal length of the color optical engine, with the unit of mm.

[0044] Among them, the display image source 1 can adopt a color display image source of Raycus, with a wavelength band of 435nm - 656nm. The first imaging lens unit 2, the second imaging lens unit 3, and the third imaging lens unit 4 are all a series of lens groups with aberration correction functions. The lenses in the lens group can be made of plastic or glass, and the number of lenses in the lens group is not limited. Aspherical lenses are preferred; the fourth imaging lens unit 5 is a lens group with aberration correction and light transmission functions. At the same time, on the outermost side of the entire optical engine, it needs to have scratch-resistant function. The material of the fourth imaging lens unit 5 can be either glass or plastic, and glass aspherical lenses are preferred.

[0045] The implementation principle of this optical engine is that the light emitted by the display image source 1 passes through the first imaging lens unit 2 and then is transmitted to the second imaging lens unit 3, and then is transmitted to the third imaging lens unit 4 via the second imaging lens unit 3. The outermost lens of the third imaging lens unit 4 is preferably a glass aspherical lens, which can increase the scratch-resistant ability of the outermost lens and improve the service life while ensuring the imaging effect. Finally, it is transmitted to the entrance pupil of the waveguide, as Figure 1 shown.

[0046] In one embodiment, the color optical engine also satisfies the following conditions:

[0047] -20 ≤ C11 ≤ -6; 5 ≤ C12 ≤ 20; 1 ≤ C21 ≤ 8; 5 ≤ C22 ≤ 20;

[0048] 2 ≤ C31 ≤ 15; 2 ≤ C32 ≤ 15; -25 ≤ C41 ≤ -6; 10 ≤ C42 ≤ 30;

[0049] Wherein, C11 is the curvature radius of the light incident surface of the first imaging lens unit 2, C12 is the curvature radius of the light exiting surface of the first imaging lens unit 2, C21 is the curvature radius of the light incident surface of the second imaging lens unit 3, C22 is the curvature radius of the light exiting surface of the second imaging lens unit 3, C31 is the curvature radius of the light incident surface of the third imaging lens unit 4, C32 is the curvature radius of the light exiting surface of the third imaging lens unit 4, C41 is the curvature radius of the light incident surface of the fourth imaging lens unit 5, and C42 is the curvature radius of the light exiting surface of the fourth imaging lens unit 5, with the unit of mm. By reasonably setting the mirror surface curvature radii of each imaging lens unit, it helps to ensure the imaging quality while further achieving miniaturization and light weight.

[0050] In one embodiment, the color optical machine further satisfies the following conditions:

[0051] 0.5 ≤ d1 ≤ 3.0; 0.3 ≤ d2 ≤ 2.0; 0.5 ≤ d3 ≤ 3.0; 0.3 ≤ d4 ≤ 2.0;

[0052] 0.3 ≤ D1 ≤ 2.0; 0.15 ≤ D2 ≤ 2.0; 0.15 ≤ D3 ≤ 2.0; 0.15 ≤ D4 ≤ 2.0;

[0053] Wherein, d1 is the thickness of the first imaging lens unit 2, d2 is the thickness of the second imaging lens unit 3, d3 is the thickness of the third imaging lens unit 4, d4 is the thickness of the fourth imaging lens unit 5, D1 is the air gap between the first imaging lens unit 2 and the display image source 1, D2 is the air gap between the second imaging lens unit 3 and the first imaging lens unit 2, D3 is the air gap between the third imaging lens unit 4 and the second imaging lens unit 3, and D4 is the air gap between the fourth imaging lens unit 5 and the third imaging lens unit 4, with the unit of mm. By reasonably setting the thicknesses of each imaging lens unit and the air gaps, it helps to ensure the imaging quality while further achieving miniaturization and is convenient for processing.

[0054] In one embodiment, the first imaging lens unit 2 includes a first lens, and the light incident surface of the first lens is convex and the light exiting surface is convex; the second imaging lens unit 3 includes a second lens, and the light incident surface of the second lens is concave and the light exiting surface is convex; the third imaging lens unit 4 includes a third lens, and the light incident surface of the third lens is concave and the light exiting surface is convex; the fourth imaging lens unit 5 includes a fourth lens, and the light incident surface of the fourth lens is convex and the light exiting surface is convex. By reasonably designing the number of lenses and the surface types of each imaging lens unit, it helps to achieve miniaturization and light weight and improve the imaging quality. It is easy to understand that the specific number of lenses and surface types can also be adjusted according to actual requirements.

[0055] In one embodiment, the color light engine further satisfies the following conditions:

[0056] 1.5 ≤ n1 ≤ 1.8; 30 ≤ Vd1 ≤ 60; 1.5 ≤ n2 ≤ 1.8; 30 ≤ Vd2 ≤ 60;

[0057] 1.6 ≤ n3 ≤ 1.9; 10 ≤ Vd3 ≤ 40; 1.5 ≤ n4 ≤ 1.8; 40 ≤ Vd4 ≤ 70;

[0058] Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, Vd1 is the Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, and Vd4 is the Abbe number of the fourth lens. By reasonably designing the refractive index and Abbe number of each lens, chromatic aberration can be reduced and the imaging quality can be further improved.

[0059] In one embodiment, the color light engine further includes a diaphragm 6, and the diaphragm 6 is located on the light-emitting side of the fourth imaging lens unit 5 and satisfies the following conditions:

[0060] -0.5 ≤ D5 ≤ 0.5;

[0061] Wherein, D5 is the air gap between the diaphragm 6 and the fourth imaging lens unit 5, with the unit of mm. The diaphragm 6 can adjust the light flux to adapt to different scenarios.

[0062] In one embodiment, the surface type of each lens is one of spherical surface, aspherical surface, freeform surface, Fresnel surface, and plane.

[0063] In one embodiment, the aspherical surface is an even-order aspherical surface type and satisfies the following formula:

[0064]

[0065] Wherein, z is the sag height, Y is the lens center height, k is the conic coefficient, C is the curvature, a i is the i-th aspherical coefficient, and N is a positive integer.

[0066] In one embodiment, antireflection films are provided on both the light-incident surface and the light-emitting surface of each lens, and an ink layer is also coated on the outer edge of each lens. The outermost lens of the fourth imaging lens unit 5 is a glass lens. Among them, antireflection films need to be evaporated on each lens surface, and the edges are blackened, which can effectively suppress stray light. By using a glass material for the outermost lens, it has an anti-scratch function, which helps to further improve the service life and ensure the imaging quality.

[0067] In one embodiment, the display image source 1 is a Micro OLED display or a Micro LED display. Preferably, it is a MicroLED display, or other displays well-known to those skilled in the art can also be used.

[0068] The volumes of existing color light engines are very large. Especially when using DLP displays or LCOS displays, their power consumptions are relatively high and the contrast ratios are very poor. The color light engine of this application can use as few as four lenses and by adopting a Micro LED display or a Micro OLED display, its volume and weight are much smaller than those of existing light engines, and it has low power consumption and high contrast, meeting the usage requirements for color scenarios. Moreover, through reasonable design of optical parameters (including focal length, thickness, air gap, radius of curvature, refractive index, Abbe number, etc.), while ensuring miniaturization and light weight, it has high image quality, a large FOV, and small chromatic aberration, meeting the usage requirements for matching with waveguides and the color requirements of the color light engine, making the entire AR glasses field approach the form of glasses while having a good color effect, greatly improving the comfort and experience of users wearing them.

[0069] Embodiment 1:

[0070] The display image source 1 of this embodiment is designed with reference to a 0.22-inch full-color screen, with a pixel number of 640*480, and the effective size of the display image source is 4.58mm*3.44mm. The optical parameters are shown in Tables 1 and 2.

[0071] Table 1

[0072]

[0073]

[0074] Among them, OBJ represents the object plane, Stop is the aperture stop, S2 represents the light-emitting surface of the fourth imaging lens unit, S3 represents the light-incident surface of the fourth imaging lens unit, S4 represents the light-emitting surface of the third imaging lens unit, S5 represents the light-incident surface of the third imaging lens unit, S6 represents the light-emitting surface of the second imaging lens unit, S7 represents the light-incident surface of the second imaging lens unit, S8 represents the light-emitting surface of the first imaging lens unit, S9 represents the light-incident surface of the first imaging lens unit, and S10 represents the light-emitting surface of the display image source.

[0075] Table 2

[0076]

[0077] According to the above parameters, the FOV of the light engine in this embodiment is 30°, and the total optical length < 10mm. As Figure 2 shown, the MTF graph shows that MTF > 0.5@125lp / mm. As Figure 3As shown, the size of the spot diagram for each field of view is within 2 pixel sizes. The overall optical length is relatively small, the image quality is relatively high, and a full-color effect can be achieved. Compared with various existing full-color optical engines, it has a smaller volume and lighter weight.

[0078] Embodiment 2:

[0079] The display image source 1 in this embodiment is designed with reference to a 0.22-inch full-color screen, with 640*480 pixels, and the effective size of the display image source is 4.58mm*3.44mm. The optical parameters are shown in Tables 3 and 4.

[0080] Table 3

[0081]

[0082]

[0083] Among them, OBJ represents the object plane, Stop is the aperture stop, S2 represents the exit surface of the fourth imaging lens unit, S3 represents the entrance surface of the fourth imaging lens unit, S4 represents the exit surface of the third imaging lens unit, S5 represents the entrance surface of the third imaging lens unit, S6 represents the exit surface of the second imaging lens unit, S7 represents the entrance surface of the second imaging lens unit, S8 represents the exit surface of the first imaging lens unit, S9 represents the entrance surface of the first imaging lens unit, and S10 represents the exit surface of the display image source.

[0084] Table 4

[0085]

[0086] According to the above parameters, the FOV of the optical engine in this embodiment is 30°, and the overall optical length <10mm. As Figure 4 shown, the MTF diagram shows that MTF>0.5@125lp / mm. As Figure 5 shown, the size of the spot diagram for each field of view is within 2 pixel sizes. The overall optical length is relatively small, the image quality is relatively high, and a full-color effect can be achieved. Compared with various existing full-color optical engines, it has a smaller volume and lighter weight.

[0087] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0088] The above-described embodiments only represent relatively specific and detailed embodiments of the present application, but should not be construed as limiting the scope of the patent of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A color optical engine, characterized in that: The color optical engine includes a display image source (1), a first imaging lens unit (2), a second imaging lens unit (3), a third imaging lens unit (4), and a fourth imaging lens unit (5) arranged in sequence along the optical axis. Each of the imaging lens units includes at least one lens. The display image source (1) is configured to emit color light, and the color optical engine satisfies the following conditions: 5 ≤ f1 ≤ 15; 10 ≤ f2 ≤ 20; -10 ≤ f3 ≤ -2; 5 ≤ f4 ≤ 15; 5 ≤ f ≤ 15; where f1 is the focal length of the first imaging lens unit (2), f2 is the focal length of the second imaging lens unit (3), f3 is the focal length of the third imaging lens unit (4), f4 is the focal length of the fourth imaging lens unit (5), and f is the focal length of the color optical engine, with the unit of mm.

2. The color optical engine according to claim 1, characterized in that: The color optical engine also satisfies the following conditions: -20 ≤ C11 ≤ -6; 5 ≤ C12 ≤ 20; 1 ≤ C21 ≤ 8; 5 ≤ C22 ≤ 20; 2 ≤ C31 ≤ 15; 2 ≤ C32 ≤ 15; -25 ≤ C41 ≤ -6; 10 ≤ C42 ≤ 30; where C11 is the radius of curvature of the incident surface of the first imaging lens unit (2), C12 is the radius of curvature of the exit surface of the first imaging lens unit (2), C21 is the radius of curvature of the incident surface of the second imaging lens unit (3), C22 is the radius of curvature of the exit surface of the second imaging lens unit (3), C31 is the radius of curvature of the incident surface of the third imaging lens unit (4), C32 is the radius of curvature of the exit surface of the third imaging lens unit (4), C41 is the radius of curvature of the incident surface of the fourth imaging lens unit (5), and C42 is the radius of curvature of the exit surface of the fourth imaging lens unit (5), with the unit of mm.

3. The color optical engine according to claim 1, characterized in that: The color optical engine also satisfies the following conditions: 0.5 ≤ d1 ≤ 3.0; 0.3 ≤ d2 ≤ 2.0; 0.5 ≤ d3 ≤ 3.0; 0.3 ≤ d4 ≤ 2.0; 0.3 ≤ D1 ≤ 2.0; 0.15 ≤ D2 ≤ 2.0; 0.15 ≤ D3 ≤ 2.0; 0.15 ≤ D4 ≤ 2.0; where d1 is the thickness of the first imaging lens unit (2), d2 is the thickness of the second imaging lens unit (3), d3 is the thickness of the third imaging lens unit (4), d4 is the thickness of the fourth imaging lens unit (5), D1 is the air gap between the first imaging lens unit (2) and the display image source (1), D2 is the air gap between the second imaging lens unit (3) and the first imaging lens unit (2), D3 is the air gap between the third imaging lens unit (4) and the second imaging lens unit (3), and D4 is the air gap between the fourth imaging lens unit (5) and the third imaging lens unit (4), with the unit of mm.

4. The color optical engine according to claim 1, wherein: The first imaging lens unit (2) includes a first lens, and the incident light surface of the first lens is convex and the outgoing light surface is convex; the second imaging lens unit (3) includes a second lens, and the incident light surface of the second lens is concave and the outgoing light surface is convex; the third imaging lens unit (4) includes a third lens, and the incident light surface of the third lens is concave and the outgoing light surface is convex; the fourth imaging lens unit (5) includes a fourth lens, and the incident light surface of the fourth lens is convex and the outgoing light surface is convex.

5. The color optical engine according to claim 4, characterized in that: The color optical engine further satisfies the following conditions: 1.5 ≤ n1 ≤ 1.8; 30 ≤ Vd1 ≤ 60; 1.5 ≤ n2 ≤ 1.8; 30 ≤ Vd2 ≤ 60; 1.6 ≤ n3 ≤ 1.9; 10 ≤ Vd3 ≤ 40; 1.5 ≤ n4 ≤ 1.8; 40 ≤ Vd4 ≤ 70; Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, Vd1 is the Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, and Vd4 is the Abbe number of the fourth lens.

6. The color optical engine according to claim 1, wherein: The color optical engine further includes a diaphragm (6), the diaphragm (6) is located on the outgoing light side of the fourth imaging lens unit (5), and satisfies the following conditions: -0.5≤D5≤0.5； Wherein, D5 is the air gap between the diaphragm (6) and the fourth imaging lens unit (5), in mm.

7. The color optical engine according to claim 1, characterized in that: The surface type of each of the lenses is one of spherical surface, aspherical surface, freeform surface, Fresnel surface, and plane surface.

8. The color optical engine according to claim 7, wherein: The aspherical surface is an even-order aspherical surface type and satisfies the following formula: Among them, z is the sagitta, Y is the lens center height, k is the conic coefficient, C is the curvature, a i is the i-th aspheric coefficient, and N is a positive integer.

9. The color optical engine according to claim 1, characterized in that: An antireflection film is provided on both the incident light surface and the outgoing light surface of each of the lenses, and an ink layer is also coated on the outer edge of each of the lenses. The outermost lens of the fourth imaging lens unit (5) is a glass lens.

10. The color optical engine according to claim 1, characterized in that: The display image source (1) is a Micro OLED display or a Micro LED display.

Images