Miniature projection ray machine
The micro-projection optical-mechanical structure that combines the image source with the polygonal optical path adjustment prism solves the problem of insufficient utilization of image source light, realizes an efficient and compact micro-projection optical-mechanical design, and improves the lighting efficiency and display effects.
Patent Information
- Application Number
- CN202423125154.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2025-10-14
- Estimated Expiration
- 2034-12-17
AI Technical Summary
The light emitted by the image source in existing AR optical modules is not fully utilized, resulting in brightness loss, increasing battery consumption and device size, and affecting display effects.
The structure that combines the image source with the polygonal optical path adjustment prism eliminates the polarization splitting system, realizes the optical path transmission through the polygonal prism, uses aspheric surface and anti-reflection film to improve the light efficiency, and combines the positive and negative optical focal length lens group to focus the light beam and correct the aberration.
A low-power, high-contrast micro-projection optical machine has been realized, with the light efficiency increased to 80%~98%. The structure is compact, and the size and weight of the equipment are reduced.
Smart Images
Figure CN223436188U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of near-eye display, in particular to a micro projection light engine. BACKGROUND
[0002] In the AR light module scheme, the light waveguide sheet scheme occupies a very important position in the AR market because of the advantages of high transmittance, ultra-thinness and the closest shape to the conventional glasses. Considering the maturity of the processing technology, the current AR waveguide scheme most widely used is one-dimensional geometric light waveguide.
[0003] At present, the light engine part of the one-dimensional geometric waveguide AR light module mainly uses a polarized light splitting system made of glass to fold the light path for sharing to reduce the volume at a field of view angle of 30° or more. The polarized light splitting system generally includes two right-angle prisms, the inclined surfaces of which are glued together, and a polarized light splitting film is arranged on the glued surface, which can reflect or transmit light of a polarized state; meanwhile, it also contains one or two 1 / 4 wave plates to change the polarization state of light, so that the light of the polarized state finally completes the common light path. However, due to the use of the polarized light splitting system, the light efficiency of the light engine is generally < 35%, and the light emitted by the image source cannot be fully utilized, resulting in a loss of brightness and affecting the display effect; to achieve the desired brightness, a brighter image source is needed, and this scheme generally uses an LCOS image source, and increases the illumination system of the LED light-emitting system, the increase of the brightness requirement will increase the power consumption, and the heat generation of the AR light module will also increase, and the use time of the battery will also decrease; and the use of the illumination system will also increase the volume and weight of the AR light module. CONTENT OF THE UTILITY MODEL
[0004] The present application provides a micro projection light engine which can solve the problem that the light emitted by the image source cannot be fully utilized.
[0005] A micro projection light engine, comprising:
[0006] an image source;
[0007] a first lens group arranged in the light emission direction of the image source, the first lens group being used for collimating image light and correcting aberration; and a polygonal light path adjusting prism arranged in the light emission direction of the first lens group, the polygonal light path adjusting prism comprising a light incidence surface for coupling in light rays and a light emission surface for coupling out light rays, the image light emitted by the image source passing through the first lens group to correct aberration and then passing through the light incidence surface and the reflecting surface in sequence and being emitted from the light emission surface.
[0008] By using the above structure, the combination of the image source and the polygonal imaging prism is adopted, the light efficiency loss caused by the polarization light splitting system is avoided, the overall structure of the micro projection light machine provided in the application is relatively compact, the light path transmission is completed in the polygonal imaging prism, the low power consumption and high contrast can be ensured, and the miniaturization of the micro projection light machine structure can be better realized.
[0009] In one of the embodiments of the application, the reflecting surface is an aspherical surface.
[0010] The reflecting surface corrects the aberration when adjusting the transmission direction of the light path, and the miniaturization of the AR micro projection light machine can be realized without an additional lens light path.
[0011] In one of the embodiments of the application, the polygonal light path adjusting prism includes one reflecting surface or two reflecting surfaces.
[0012] The polygonal light path adjusting prism with one reflecting surface or two reflecting surfaces can be selected based on the requirement of the imaging quality, and the diversification of the imaging light path is realized.
[0013] In one of the embodiments of the application, when the polygonal light path adjusting prism includes two reflecting surfaces, a connecting surface is further arranged between the two reflecting surfaces, the connecting surface is connected at an angle with the two reflecting surfaces, the connecting surface is a non-smooth surface or is coated with light extinction paint.
[0014] By using the above scheme, the light emitted by the light incident surface from the connecting surface can be avoided to form stray light.
[0015] In one of the embodiments of the application, when the polygonal light path adjusting prism includes two reflecting surfaces, the two reflecting surfaces can be selected as off-axis or non-off-axis curved surfaces, and if the off-axis curved surface is selected, the off-axis direction is the direction in which the incident angle is reduced.
[0016] By using the above scheme, the off-axis curved surface can further reduce the aberration, and the light path and the image quality can be optimized.
[0017] In one of the embodiments of the application, the light incident surface and the light emitting surface are coated with an anti-reflection film.
[0018] By using the above scheme, the anti-reflection film coated on the light incident surface and the light emitting surface can reduce the reflection loss of the light, improve the light transmittance, and thus improve the light efficiency and the brightness.
[0019] In one of the embodiments of the application, the focal length f1 of the first lens group is less than 0, and the first lens group is a negative focal length component.
[0020] By using the above scheme, the negative focal length of the first lens group helps to adjust the focusing of the light beam, so that the image light can be better focused on the projection surface.
[0021] In one of the embodiments of the present application, the micro projection light engine further comprises a second lens group, which is arranged on the light exit surface of the polygonal light path adjusting prism, and the focal length f2>0 of the second lens group is a positive lens group.
[0022] By using the above scheme, the positive focal length of the second lens group helps to further focus and shape the image light, ensuring the clarity of the image on the projection surface.
[0023] In one of the embodiments of the present application, the thickness d of the first lens group and the second lens group satisfies: d≤6mm.
[0024] By using the above scheme, the thickness d of the lens group is less than or equal to 6mm, which helps to reduce the volume of the light engine and make it more miniaturized, facilitating integration into portable devices.
[0025] In one of the embodiments of the present application, the distance L1 between the first lens group and the polygonal light path adjusting prism satisfies: L1≤5mm; and the distance L2 between the polygonal light path adjusting prism and the second lens group on the optical axis satisfies: L2≤5mm.
[0026] By using the above scheme, the distance L1 between the first lens group and the polygonal light path adjusting prism, and the distance L2 between the polygonal light path adjusting prism and the second lens group on the optical axis are both less than or equal to 5mm, which helps to reduce the overall size of the light engine, and at the same time, may help to reduce optical distortion and improve light efficiency.
[0027] In summary, the present application includes at least one of the following beneficial technical effects:
[0028] 1. The micro projection light engine provided by the present application uses a self-luminous image source such as OLED or micro-LED, which can ensure low power consumption and high contrast. The combination of the image source and the polygonal prism eliminates the light efficiency loss caused by the polarization light splitting system. The micro projection light engine provided by the present application has a compact overall structure, and the light path transmission is completed in the polygonal prism, thereby realizing the miniaturization of the micro projection light engine structure and overcoming the complex problem of light path calibration and positioning for each mirror in the prior art.
[0029] 2. By controlling the curvature radii of the first reflecting surface and the second reflecting surface, the correction of aberration can be realized.
[0030] 3. By setting the connecting surface between the two reflecting surfaces as a non-smooth surface or coating it with a light-absorbing paint, the polygonal prism includes a light entrance surface for coupling in light and a light exit surface for coupling out light, and the light entrance surface and the light exit surface are both coated with an anti-reflection film, so that the image light can be reflected by the reflecting surface and then exit through the light exit surface, improving the light efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 Schematic diagram of the optical structure of a micro-projection optical engine provided in the first embodiment of the present application;
[0032] Figure 2 This is a schematic diagram of the optical structure of a micro-projection optical engine provided in the second embodiment of the present application;
[0033] Figure 3 This is a schematic diagram of the optical structure of a micro-projection optical engine provided in the third embodiment of the present application.
[0034] Explanation of the accompanying symbols: 1. Image source; 2. First lens group; 3. Polygonal optical path adjustment prism; 30. Light incident surface; 32. Reflection surface; 320. First reflection surface; 330. Second reflection surface; 33. Connecting surface; 31. Light exit surface; 4. Second lens group. DETAILED DESCRIPTION
[0035] Therefore, it is necessary to provide a micro-projection optical machine.
[0036] The following is combined with Figures 1-3 The micro-projection optical engine provided in this application is further described in detail. The micro-projection optical engine is used for AR smart glasses.
[0037] Example 1
[0038] See also Figure 1 , which is a micro-projection optical machine provided in the first embodiment of the present application, includes: an image source 1, a first lens group 2 and a polygonal optical path adjustment prism 3.
[0039] Specifically, the image source 1 can emit light on its own. For example, it can be OLED, Micro-LED or mini-LED. The first lens group 2 is arranged in the light-emitting direction of the image source 1. The first lens group 2 is used to collimate the image light to a certain extent and correct the aberration. The thickness d of the first lens group 2 satisfies: d≤6mm. More specifically, the setting of the first lens group 2 has three functions. First, it can focus the light so that the light emitted by the image source 1 can be projected onto the screen more concentratedly, thereby improving the clarity and brightness of the image, and facilitating the subsequent light path to be transmitted along a unified path, which can reduce the stray light incident on adjacent surfaces; second, correcting distortion: the first lens group 2 can perform distortion correction on the light generated by the image source 1 to reduce image distortion caused by optical distortion, such as pincushion distortion or barrel distortion.
[0040] There are no strict regulations on the number of lenses and lens parameters included in the first lens group 2, as long as it is a negative optical focal length component and the focal length f1<0.
[0041] The polygonal optical path adjustment prism 3 is disposed in the light-emitting direction of the first lens group 2. In this embodiment, the polygonal optical path adjustment prism 3 is hexagonal and includes a reflective surface 32. Specifically, the polygonal optical path adjustment prism 3 includes a light incident surface 30 for coupling in light, a reflective surface 32, and a light exit surface 31 for coupling out light. The light incident surface 30 and the light exit surface 31 are arranged at an angle. After the image light emitted by the image source 1 is corrected for aberrations by the first lens group 2, it passes through the light incident surface 30 and the reflective surface 32 in sequence before exiting from the light exit surface 31. The light exiting from the light exit surface 31 is parallel light.
[0042] The relative position of light incident surface 30 with respect to first lens group 2 can be adjusted to maximize light utilization, allowing more light to enter polygonal optical path adjustment prism 3 while preventing stray light from entering other surfaces adjacent to reflective surface 32. In this embodiment, the distance L1 along the optical axis between first lens group 2 and polygonal optical path adjustment prism 3 satisfies the requirement of L1 ≤ 5 mm. In this embodiment, reflective surface 32 is coated with an antireflection coating (not shown).
[0043] In this embodiment, the reflective surface 32 is an aspheric surface, and the reflective surface 32 can be an off-axis or non-off-axis curved surface according to the requirements of the optical path. If it is off-axis, the off-axis direction is the direction that reduces the incident angle of the incident light; the off-axis curved surface refers to the reflective surface 32 that is offset relative to the optical axis (optical axis) of the system.
[0044] Off-axis reflection can reduce or avoid spherical distortion and astigmatism. Excessive off-axis reflection can cause the beam's angle of incidence on the optical element to be too large, exceeding the effective reflection or refraction range of the optical element and resulting in reduced beam quality. Excessive off-axis reflection can limit the system's field of view, failing to cover the desired observation area. In short, improperly setting the off-axis reflection can increase light loss in the optical system, especially when using a reflector or prism, where light may miss the reflective surface 32 and be lost.
[0045] Example 2
[0046] See also Figure 2 , Figure 2 The second embodiment of the present application provides a micro-projection optical engine. The micro-projection optical engine provided in the second embodiment is substantially the same as that in the first embodiment, except that, in this embodiment, the polygonal optical path adjustment prism 3 is pentagonal and the light exit surface 31 is convex. In a further embodiment, the off-axis distance of the light exit surface 31 is less than the maximum width of the light exit surface 31.
[0047] In this embodiment, there are two reflective surfaces 32, namely, a first reflective surface 320 and a second reflective surface 330. The first and second reflective surfaces 320 and 330 are connected by a non-smooth connection surface 33, which is coated with matte paint (not shown). This arrangement ensures that all light projected from the light incident surface 30 is projected onto the first reflective surface 320, ensuring that the light path is transmitted along a uniform path as much as possible, eliminating stray light and improving imaging quality.
[0048] Example 3
[0049] See also Figure 3 , Figure 3 The third embodiment of the present application provides a micro-projection optical engine. In this embodiment, the micro-projection optical engine further includes a second lens group 4, which is disposed on the light exit surface 31 of the polygonal optical path adjustment prism 3. The second lens group 4 is used to correct the aberrations emitted from the polygonal optical path adjustment prism 3 and further fine-tune the aberrations. The focal length f2 of the second lens group 4 is greater than 0, indicating a positive optical power component. The number of lenses included in the second lens group 4 and the lens parameters are not strictly specified; as long as the components are positive optical power and the focal length f2 is greater than 0, the second lens group 4 can be used.
[0050] The thickness d of the second lens group 4 is ≤ 6 mm, and the distance between the polygonal optical path adjustment prism 3 and the second lens group 4 along the optical axis is ≤ 5 mm. Within this distance range, a positive lens is used to shorten the optical path length to make the system more compact while maintaining the required imaging quality.
[0051] To sum up, by adopting the technical solution of the present application, since there is no need to use a polarization system, the light efficiency loss of the micro-projection optical machine is mainly due to the absorption of the material, the light efficiency is improved to between 80% and 98%, and the mass of the micro-projection optical machine can also be controlled within 20g.
[0052] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.
Claims
1. A micro-projection optical machine, characterized in that: include: Image source (1); A first lens group (2) is arranged in the light-emitting direction of the image source (1), and the first lens group (2) is used to collimate the image light and correct aberrations; as well as A polygonal optical path adjustment prism (3) is arranged in the light-emitting direction of the first lens group (2). The polygonal optical path adjustment prism (3) comprises a light incident surface (30) for coupling in light, a reflection surface (32), and a light exit surface (31) for coupling out light. Image light emitted by the image source (1) passes through the first lens group (2) to correct aberrations, then sequentially passes through the light incident surface (30) and the reflection surface (32) before exiting from the light exit surface (31).
2. The micro-projection optical engine according to claim 1, characterized in that: The reflecting surface (32) is a spherical surface or an aspherical surface.
3. The micro-projection optical engine according to claim 2, characterized in that: The reflecting surface (32) is an off-axis or non-off-axis curved surface, and if it is an off-axis curved surface, the off-axis direction is a direction that reduces the incident angle of the incident light.
4. The micro-projection optical engine according to claim 3, characterized in that: The polygonal optical path adjustment prism (3) comprises one reflecting surface (32) or two reflecting surfaces (32).
5. The micro-projection optical engine according to claim 3, characterized in that: When the polygonal optical path adjustment prism (3) includes two reflecting surfaces (32), a connecting surface (33) is further provided between the two reflecting surfaces (32), the connecting surface (33) is connected to the two reflecting surfaces (32) at an angle, and the connecting surface (33) is provided as a non-smooth surface or coated with matte paint.
6. The micro-projection optical engine according to claim 1, characterized in that: The focal length f1 of the first lens group (2) is less than 0, and the first lens group (2) is a negative optical power component.
7. The micro-projection optical engine according to claim 6, characterized in that: The micro-projection optical machine further comprises a second lens group (4), which is arranged on the light exit surface (31) of the polygonal optical path adjustment prism (3), and the focal length f2 of the second lens group (4) is greater than 0, and the second lens group (4) is a positive optical power component.
8. The micro-projection optical engine according to claim 7, characterized in that: The thickness d of the first lens group (2) and the second lens group (4) both satisfy: d≤6mm.
9. The micro-projection optical engine according to claim 8, characterized in that: The distance L1 between the first lens group (2) and the polygonal optical path adjustment prism (3) along the optical axis satisfies: L1≤5mm; and the distance L2 between the polygonal optical path adjustment prism (3) and the second lens group (4) on the optical axis satisfies: L2≤5mm.
10. The micro-projection optical engine according to any one of claims 1 to 9, characterized in that: The light incident surface (30) and the light exit surface (31) are both coated with anti-reflection films.