Laser projector
By integrating optical devices with free curved mirrors and diffusion surfaces, the problem of large volumes in laser projectors is solved, and the miniaturization and portability of laser projectors are achieved.
Patent Information
- Application Number
- CN202410031847.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-08
- Publication Date
- 2025-07-08
AI Technical Summary
There are many optical devices in existing laser projectors, resulting in larger volumes.
Optical devices that integrate free curved mirrors and diffusion surfaces are adopted to replace traditional reflectors, convergence lenses and diffusion sheets to realize laser reflection, convergence and uniform light processing, and reduce the number of optical devices.
It effectively reduces the use of optical devices, shortens the optical path, reduces the volume of the laser projector, and improves portability.
Smart Images
Figure CN120276201A_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present application relate to optoelectronic technologies. More specifically, it relates to a laser projector. Background Art
[0002] A laser projector is a projection device that uses laser beams to project images. Due to its advantages such as high brightness and rich colors, it has been widely used.
[0003] In some related technologies, for a projector system based on LCOS (Liquid Crystal on Silicon), the laser output by the laser successively passes through optical devices such as a wave plate, a diffuser, a mirror, a focusing lens, and a diffuser wheel and is incident into an optical waveguide. A spot with relatively high uniformity is formed at the outlet of the optical waveguide, and then the laser is emitted to a lens through an illumination lens or an illumination lens group, a PBS (Polarizing Beam Splitter), and an LCOS, and then projected onto a screen to achieve projection.
[0004] Since there are a large number of optical devices in the related technologies, which occupy a certain space, the volume of the laser projector is relatively large. Summary of the Invention
[0005] Embodiments of the present application provide a laser projector to solve the problem in the related technologies that a large number of optical devices occupy a certain space, resulting in a relatively large volume of the laser projector.
[0006] In a first aspect, embodiments of the present application provide a laser projector, including:
[0007] A laser for emitting laser light;
[0008] A converging device, which is obliquely placed between the light-emitting side of the laser and the light-incident side of the light homogenizing device, includes a diffusing surface and a reflecting surface. The reflecting surface is used to reflect and converge the laser, and the diffusing surface is used to homogenize the laser emitted by the laser and the light beam reflected by the reflecting surface to reduce speckle;
[0009] The light homogenizing device is located on the light-emitting side of the converging device and is used to homogenize the converged laser so that the processed laser is emitted to a projection lens through a prism assembly and a light valve modulation device.
[0010] In some embodiments of the present application, the converging device is a curved lens, and the curved lens includes a first surface and a second surface;
[0011] The first surface is a plane, serving as the diffusing surface, located on the side close to the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to homogenize the laser to reduce speckle;
[0012] The second surface is a curved surface and serves as a reflecting surface, which is located on one side away from the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to reflect the laser passing through the first surface, so that the laser exits through the first surface and converges to the light homogenizing device.
[0013] In some embodiments of the present application, the converging device includes a curved mirror and a first diffusing element;
[0014] The first diffusing element includes a diffusing surface, which is located on one side close to the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to homogenize the laser to reduce speckle;
[0015] The curved mirror includes a reflecting surface, which is located on one side away from the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to reflect the laser passing through the first diffusing element, so that the laser exits through the first diffusing element and converges to the light homogenizing device.
[0016] In some embodiments of the present application, the upper limit value of the diffusion angle of the diffusing surface is 10°, the lower limit value is 1°, or the upper limit value of the diffusion angle is 1°, and the lower limit value is 0.1°.
[0017] In some embodiments of the present application, the light homogenizing device is located at the focal point of the converging device.
[0018] In some embodiments of the present application, the inclination angle of the converging device is determined based on the optical axis of the converged laser and the optical axis of the light homogenizing device, so that the laser is perpendicularly incident on the light homogenizing device.
[0019] In some embodiments of the present application, the upper limit value of the inclination angle of the converging device is 50°, and the lower limit value is 40°.
[0020] In some embodiments of the present application, the laser projector further includes a second diffusing element, which is located between the converging device and the light homogenizing device, and is used to homogenize the laser converged by the converging device to reduce speckle.
[0021] In some embodiments of the present application, if the light valve modulation device is a liquid crystal on silicon or a liquid crystal display, the prism assembly is a polarization beam splitter prism, which is used to separate lasers with different polarization directions.
[0022] In some embodiments of the present application, the polarization directions of the lasers emitted by the laser are different, and the laser projector further includes: a phase retardation device;
[0023] The phase retardation device is located between the laser and the converging device, and is used to adjust the polarization direction of the laser emitted by the laser to obtain lasers with the same polarization direction.
[0024] The present application provides a laser projector, which includes a laser, a converging device, and a light homogenizing device. Among them, the converging device includes a diffusing surface and a reflecting surface. The diffusing surface performs light homogenization on the laser emitted by the laser to reduce speckles, and the reflecting surface reflects and converges the laser. After the converged light beam passes through the diffusing surface again for light homogenization, it is incident on the light homogenizing device for light homogenization processing. The processed laser can be emitted to a projection lens through a prism assembly, a light valve modulation assembly, etc. to achieve projection. In the laser projector of the present application, the converging device can not only reflect and converge the laser, but also perform light homogenization on the laser twice to reduce speckles. Therefore, the converging device of the present application can replace the system of a reflecting mirror converging lens and two diffuser sheets in the related art, effectively reducing the number of optical devices used, thereby reducing the occupied space and thus reducing the volume of the laser projector. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the embodiments of the present application or the implementation manners in the related art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the related art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.
[0026] Figure 1 FIG. is a schematic structural diagram of a projector system based on LCOS in the related art provided by an embodiment of the present application;
[0027] Figure 2 FIG. is a schematic diagram of the physical architecture of a laser projector provided by an embodiment of the present application;
[0028] Figure 3 FIG. is a schematic structural diagram of a laser projector provided by an embodiment of the present application;
[0029] Figure 4 FIG. is a partial structural schematic diagram of a laser projector provided by an embodiment of the present application Figure 1 ;
[0030] Figure 5 FIG. is a partial structural schematic diagram of a laser projector provided by an embodiment of the present application Figure 2 ;
[0031] Figure 6 FIG. is a schematic diagram of the optical path of a light beam vertically incident on a diffusing element provided by an embodiment of the present application;
[0032] Figure 7 FIG. is a schematic diagram of the optical path of a light beam obliquely incident on a diffusing element provided by an embodiment of the present application;
[0033] Figure 8Schematic structural diagram of a laser projector when the converging device provided by an embodiment of the present application is a curved lens;
[0034] Figure 9 Schematic structural diagram of a laser projector when the converging device provided by an embodiment of the present application includes a curved mirror and a diffusion sheet;
[0035] Figure 10 Schematic structural diagram of a laser projector when the converging device provided by an embodiment of the present application includes a curved mirror and a diffusion wheel. Detailed implementation manners
[0036] To make the objectives, implementation manners and advantages of the present application clearer, the following will clearly and completely describe the exemplary implementation manners of the present application with reference to the accompanying drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only a part rather than all of the embodiments of the present application.
[0037] It should be noted that the brief description of the terms in the present application is only for facilitating the understanding of the subsequent described implementation manners, rather than intending to limit the implementation manners of the present application. Unless otherwise specified, these terms should be understood in their ordinary and general meanings.
[0038] In addition, the terms "include" and "have" and any variations thereof are intended to cover but not exclusively include. For example, a product or device including a series of components does not necessarily have to be limited to those components clearly listed, but may include other components not clearly listed or inherent to these products or devices.
[0039] Figure 1 Schematic structural diagram of a projector system based on LCOS in a related technology provided by an embodiment of the present application. Refer to Figure 1As shown in the figure, since the LCOS system requires linearly polarized light with the same polarization direction, and the RGB three-color lasers emitted by the laser 101 have different polarization directions, a phase retardation device 102, such as a wave plate, etc., needs to be placed to adjust the polarization direction into polarized light with the same vibration direction, usually adjusted to S light, and then passes through the diffuser 103 and the mirror 104, and is incident on the focusing lens 105. After passing through the focusing lens 105, it is incident on the light guide 106 at a certain angle. To reduce the speckle effect of the system, generally, a diffusion device 107, such as a diffuser or a diffusion wheel, needs to be placed at the entrance of the light guide 106. After the inner wall of the light guide 106 reflects the light beam multiple times, a spot with higher uniformity is formed at the exit, and then passes through the illumination lens or the illumination lens group 108 and enters the PBS prism 109 to be reflected to the LCOS 110. Among them, the PBS prism 109 is used to reflect S light and transmit P light. The LCOS 110 can adjust the polarization direction of the incident polarized light by π / 2, that is, adjust the incident S light to P light. After being reflected by the substrate of the LCOS 110 to the PBS prism 109, it exits to the lens 111 and is then projected onto the screen.
[0040] Figure 1 In the related technology shown in the figure, before the light guide 106 in the optical path, it is necessary to pass through the mirror 104 and the focusing lens 105 for shaping. At the same time, to further achieve spot homogenization, usually the light beam passes through the diffusion device twice to achieve diversity in diffusion angle and phase, and reduce the speckle problem. However, since the diffusion device is usually set to two, that is, a diffusion device is respectively placed at the light source end, that is, the exit side of the laser 101, and the entrance of the light guide 106, which occupies a certain space. To sum up, four devices, namely two diffusion devices, the mirror 104 and the focusing lens 105, need to be set at the light source end. The number of optical devices used is relatively large, and the optical path size is relatively long, resulting in a relatively large volume of the projector system.
[0041] Based on the above problems, the present application provides a laser projector, which can adopt an optical device integrating a free-form surface mirror and a diffusing surface to replace the systems of lenses, mirrors, and diffuser sheets in the related art, so as to reduce the number of optical devices, optimize the system structure, and simplify the system volume. Specifically as follows: The laser emitted by the laser can enter the reflecting surface of the converging device through the diffusing surface of the converging device. The reflecting surface reflects the laser and exits again through the diffusing surface, converges to the homogenizing device, and can enter the projection lens through the homogenizing device, the prism assembly, and the light valve modulation device in sequence to achieve projection. Since the diffusing surface in the converging device of the present application can perform homogenizing treatment on the laser to eliminate speckles, and passes through the diffusing surface twice before entering the homogenizing device, the reuse of the diffusing surface is realized, replacing the two diffuser sheets in the related art. At the same time, the reflecting surface of the converging device of the present application can reflect and converge the laser, replacing the mirror and the converging lens in the related art. In summary, based on the converging device of the present application, the number of optical devices used is effectively reduced, and the occupied space is reduced, which is beneficial to shortening the optical path and reducing the volume of the laser projector.
[0042] Figure 2 is a schematic diagram of the physical architecture of a laser projector provided by an embodiment of the present application, as Figure 2 shown. After disassembling the upper housing of the laser projector, the internal structure can be divided into a light source 201, an optical engine 202, and a lens 203 according to the optical function. Among them, the light source 201 is used to provide a light source illumination beam, which is transmitted to the optical engine 202 and the lens 203 at the rear end.
[0043] The laser beam provided by the light source 201 is incident on the optical engine 102 after combining and shaping. The optical engine 102 can include the converging device, the homogenizing device, the prism assembly, and the light valve modulation device of the present application, etc. The light valve modulation device can irradiate the beam into the lens 203 through the prism assembly. The lens 203 can be an ultra-short-throw projection lens, which is used to project the beam onto the projection screen to realize the display of the projection image.
[0044] The technical solution of the present application will be described in detail below in combination with specific embodiments. These specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.
[0045] Figure 3 is a schematic diagram of the structure of a laser projector provided by an embodiment of the present application, as Figure 3 shown. The laser projector can include:
[0046] A laser 31, which is used to emit laser light;
[0047] The converging device 32 is inclined and placed between the light-emitting side of the laser 31 and the light-incident side of the light homogenizing device 33. It includes a diffusing surface S1 and a reflecting surface S2. The reflecting surface S2 is used to reflect and converge the laser, and the diffusing surface S1 is used to homogenize the laser emitted by the laser 31 and the light beam reflected by the reflecting surface S2 to reduce speckle.
[0048] The light homogenizing device 33 is located on the light-emitting side of the converging device 32 and is used to homogenize the converged laser so that the processed laser is emitted to the projection lens 36 through the prism assembly 34 and the light valve modulation device 35.
[0049] The laser 31 can be a monochromatic laser that emits one color of laser, or a two-color laser that emits two colors of laser, or a three-color laser that emits three colors of laser. The type of the laser 31 is not limited in this application.
[0050] In one implementation scenario, when the laser emitted by the laser 31 is a multi-color laser, the multi-color lasers emitted can be combined first and then enter the subsequent optical path, or they can directly enter.
[0051] The light homogenizing device 33 includes, but is not limited to, a light pipe, a fly-eye lens, etc. However, for the fly-eye lens, based on the working principle of the fly-eye lens, since the light incident on the fly-eye lens is usually collimated light, if the light homogenizing device 33 is a fly-eye lens, the light beam emitted by the laser 31 can directly enter the fly-eye lens without the converging device 32 converging the light beam emitted by the laser 31. Therefore, in this embodiment of the application, the light homogenizing device 33 is a light pipe for detailed description.
[0052] In some embodiments, the converging device 32 is a curved lens, and the curved lens includes a first surface and a second surface;
[0053] The first surface is a plane, serving as the diffusing surface S1, located on the side close to the light-emitting side of the laser 31 and the light-incident side of the light homogenizing device 33, and is used to homogenize the laser to reduce speckle;
[0054] The second surface is a curved surface, serving as the reflecting surface S2, located on the side far from the light-emitting side of the laser 31 and the light-incident side of the light homogenizing device 33, and is used to reflect the laser passing through the first surface so that the laser exits through the first surface and converges to the light homogenizing device 33.
[0055] Figure 3 In the laser projector shown in, the converging device 32 is a curved lens in this case, with its first surface being the diffusing surface S1 and the second surface being the reflecting surface S2.
[0056] In an implementation scenario, the surface of the diffusion surface S1 has a diffusion layer to diffuse the light beam emitted by the laser 31 and the light beam reflected from the reflection surface S2, so as to achieve the effects of light homogenization and speckle reduction. Since both the light beam emitted by the laser 31 and the light beam reflected from the reflection surface S2 need to pass through the diffusion surface S1, the light beam is diffusely processed twice based on the diffusion surface S1, realizing the reuse of the diffusion surface S1, effectively improving the light homogenization effect, and reducing the speckle phenomenon of the laser projector.
[0057] In an implementation scenario, to improve the reflection effect of the reflection surface S2, a total reflection film can be plated on the inner surface of the reflection surface S2 to reflect most of the light beams incident from the diffusion surface S1, avoid light beam transmission, and improve the light utilization rate.
[0058] Taking the light guide tube as the light homogenizing device 33 as an example, since the first surface serves as the diffusion surface S1 and is close to the emission direction of the laser 31 and the light inlet of the light guide tube, when the laser emitted by the laser 31 is incident on the curved surface lens, it is incident from the diffusion surface S1, reflected and converged by the reflection surface S2 of the curved surface, and then emitted from the diffusion surface S1 and converged at the light inlet of the light guide tube. After the light beam is reflected multiple times by the inner wall of the light guide tube, a uniform square light spot appears at the light outlet.
[0059] In an implementation scenario, the curved surface lens is made of glass material. Due to the dispersion coefficient of the glass material, there will be a certain dispersion effect. However, when the aperture designs of the curved surface lens and the light guide tube are appropriate, the coupling efficiency of each color can be ensured. Generally, when the thickness of the curved surface lens is relatively thin, the dispersion effect is not obvious.
[0060] As can be seen from the above, when the converging device 32 is a curved surface lens, the first surface and the second surface of the curved surface lens can be used as the diffusion surface S1 and the reflection surface S2 respectively. In some embodiments, the diffusion surface S1 and the reflection surface S2 of the converging device 32 can also be provided by two separate devices and placed obliquely in the optical path. For details, please refer to Figure 4 as shown.
[0061] Figure 4 The partial structure schematic diagram of a laser projector provided by an embodiment of the present application Figure 1 , as Figure 4 shown, the converging device 32 includes a curved surface mirror 322 and a first diffusion element 321;
[0062] The first diffusion element 321 includes a diffusion surface S1, which is located on one side close to the light emission side of the laser 31 and the light inlet side of the light homogenizing device 33, and is used for homogenizing the laser to reduce speckle;
[0063] The curved mirror 322 includes a reflecting surface S2, which is located on one side away from the light-emitting side of the laser 31 and the light-incident side of the light homogenizing device 33, and is used to reflect the laser passing through the first diffusing element 321, so that the laser exits through the first diffusing element 321 and converges to the light homogenizing device 33.
[0064] Among them, the first diffusing element 321 can be a diffusing sheet or a diffusing wheel, etc., and it includes a diffusing surface S1. Since the curved mirror 322 is used to converge the laser, the curved mirror 322 can be a concave mirror.
[0065] The curved mirror 322 and the first diffusing element 321 are two separate devices, and there can be a certain gap between them. At the same time, both the first diffusing element 321 and the curved mirror 322 are inclined in the optical path.
[0066] Figure 4 In the shown laser projector, the first diffusing element 321 is a diffusing sheet. Figure 5 Partial structure schematic diagram of a laser projector provided by an embodiment of the present application Figure 2 , Figure 5 The first diffusing element 321 shown in is a diffusing wheel.
[0067] Compared with a fixed diffusing sheet, when the first diffusing element 321 is a diffusing wheel, the phase of the light beam can be randomly changed, effectively enhancing the speckle dissipation effect and the light homogenizing effect.
[0068] When the converging device 32 includes the curved mirror 322 and the first diffusing element 321, its light beam transmission principle is basically the same as that of the converging device 32 being a curved lens. Still taking the light homogenizing device 33 as an optical duct for example. Since the first diffusing element 321 is close to the light-emitting direction of the laser 31 and the light-incident port of the optical duct, the laser emitted by the laser 31 is obliquely incident on the first diffusing element 321, and then is reflected once by the curved mirror 322, and is obliquely incident on the first diffusing element 321 again, and is incident on the optical duct for light homogenizing processing.
[0069] It should be noted that if the laser 31 emits red, green, and blue lasers, since the converging device 32 includes the curved mirror 322 and the first diffusing element 321, the light beam does not pass through the glass material and will not be affected by the material dispersion coefficient, so the situation of inconsistent focal points of the three-color lasers will not occur. At the same time, after passing through the first diffusing element 321, since the thickness of the first diffusing element 321 is relatively thin, usually about 1 mm, and the distance from the first diffusing element 321 to the light-incident port of the optical duct is limited, the dispersion effect on the three-color lasers is not obvious.
[0070] The prism assembly 34 can be a Polarizing Beam Splitter (PBS), a Total Internal Reflection (TIR) prism, etc.
[0071] The light valve modulation device 35 can be an LCOS (Liquid Crystal on Silicon), an LCD (Liquid Crystal Display), a DMD (Digital Micromirror Device), etc.
[0072] An embodiment of the present application provides a laser projector. The laser emitted by the laser 31 can enter the reflecting surface S2 of the converging device 32 through the diffusing surface S1 of the converging device 32. After being reflected by the reflecting surface S2, it exits through the diffusing surface S1 again and converges to the light homogenizing device 33. The light homogenizing device 33 can perform light homogenizing processing on the converged laser and exit through a prism device, a light valve modulation device 35, etc. to the projection lens 36 to achieve projection. In the laser projector of the present application, before the laser enters the light homogenizing device 33, two light homogenizing processes can be realized based on the diffusing surface S1 of the converging device 32 to reduce speckle, replacing two diffuser plates in the related art. At the same time, based on the reflecting surface S2 of the converging device 32, the reflection and convergence of the laser are realized, replacing the reflecting mirror and the converging lens in the related art. In summary, the converging device 32 of the present application can replace four optical devices such as two diffuser plates, a reflecting mirror, and a converging lens in the related art, reducing the number of optical devices, reducing the occupied space, shortening the optical path size, thereby realizing the reduction of the volume of the laser projector and being beneficial to improving portability.
[0073] In one or more embodiments of the present application, if the light homogenizing device 33 is a light guide tube, and the converging device 32 converges the laser to obtain a light spot. To improve the light collection efficiency, the upper limit value of the light spot size can be set to the cross-sectional diameter of the light guide tube.
[0074] Taking the converging device 32 including a curved reflecting mirror 322 and a first diffusing element 321 as an example for illustration. Since generally, the main optical axis of the light beam is perpendicular to the surface of the diffusing element, Figure 6 This is an optical path schematic diagram of a light beam vertically incident on a diffusing element provided by an embodiment of the present application. Refer to Figure 6 As shown, if the microstructure of the diffusing element is a concave mirror, after the parallel light is incident, the light beam diverges, and the reflected extension line of the light beam intersects at the focal point f of the micro concave mirror.
[0075] In the present application, an inclined method is adopted, that is, the light beam is obliquely incident on the diffusing element, Figure 7Schematic diagram of an optical path where a light beam is obliquely incident on a diffusion element provided by an embodiment of the present application. Refer to Figure 7 As shown, after the diffusion element is placed obliquely, parallel light is incident at an oblique angle. After the light beam is diffused by the diffusion element, the light beam incident on the curved mirror 322 also has a certain angle. The reverse extension line of the divergent light is on the focal plane of the micro concave mirror. It can be seen that the divergent light is slightly inclined towards the diffusion element, and the diffusion angle is slightly larger.
[0076] At the same time, as the optical path increases, the diffusion angle of the edge light beam of the collimated light beam will increase. When it is incident on the inclined diffusion element, the diffusion angle further increases, that is, for the light beam between the laser 31 and the inclined diffusion element, the larger the optical path, the larger the corresponding diffusion angle, and the spot on the curved mirror 322 becomes larger; when it is reflected by the curved mirror 322 and enters the diffusion element again, the reflected optical path of the incident light with a smaller original optical path becomes larger. Therefore, when it passes through the diffusion element again, its diffusion angle is larger than that of other reflected light beams, resulting in an increase in the spot size incident on the light guide tube.
[0077] Based on the principle of geometric optics, it can be known that the incident parallel light is converged by the curved mirror 322 after passing through the inclined diffusion element. Compared with the situation where the parallel light is vertically incident and reflected, due to the increase in the incident light angle, its converging light spot expands from an ideal point to a spot with a certain size. However, since the light inlet of the light guide tube also has a certain size, it only needs to satisfy that the spot size is less than or equal to the cross-sectional diameter of the light guide tube, which does not affect the light collection efficiency.
[0078] As can be seen from the above, there are also certain requirements for the diffusion angle of the diffusion element. The above diffusion element can be used to refer to the first diffusion element 321 in the embodiment of the present application or the first surface of the curved lens as the diffusion surface S1. In one implementation scenario, the upper limit value of the diffusion angle of the diffusion surface S1 is 10°, and the lower limit value is 1°. Or, the upper limit value of the diffusion angle is 1°, and the lower limit value is 0.1°. It can be any diffusion angle within the range of 0.1° - 1°, or any diffusion angle within the range of 1° - 10°.
[0079] In another implementation scenario, if the spot size is larger than the cross-sectional diameter of the light guide tube, at this time, part of the light will be incident into the light guide tube, and projection can also be realized. At this time, the light collection efficiency will be relatively low.
[0080] In some embodiments, since the converging device 32 converges the laser to obtain a spot, and the spot position is at the focal point of the converging device 32, the light homogenizing device 33 is located at the focal point of the converging device 32. Specifically, the light inlet of the light homogenizing device 33 can be located at the focal point of the converging device 32 so that most of the light can enter the light inlet of the light homogenizing device 33.
[0081] In one implementation scenario, when the converging device 32 is a curved lens, the focal point of the converging device 32 is the focal point of the curved lens. In another implementation scenario, when the converging device 32 includes two elements, namely a curved mirror 322 and a first diffusing element 321, the focal point of the converging device 32 is the focal point of the curved mirror 322.
[0082] In some embodiments, since the converging device 32 is inclined in the optical path, the inclination angle of the converging device 32 is determined based on the optical axis of the converged laser and the optical axis of the light homogenizing device 33, so that the laser is incident perpendicularly on the light homogenizing device 33.
[0083] Still taking the light duct as the light homogenizing device 33 as an example, since the converged light beam of the converging device 32 needs to be incident on the light inlet of the light duct, and the light inlet of the light duct has a certain size, in order to make most of the light beam enter the light duct, the optical axis of the converged laser and the optical axis of the light duct can be made consistent. At this time, most of the converged light beam can be incident on the light duct.
[0084] When the inclination angle of the converging device 32 is too large or too small, the converged laser needs to be obliquely incident on the light duct, which will cause some light beams not to be incident on the light duct.
[0085] In one implementation scenario, the upper limit value of the inclination angle of the converging device 32 is 50°, and the lower limit value is 40°.
[0086] In summary, by placing the light homogenizing device 33 at the focal point of the converging device 32, setting the diffusion angle of the diffusion surface S1 of the converging device 32, setting the inclination angle of the converging device 32, and controlling the upper limit value of the spot size to be the cross-sectional diameter of the light duct, etc., most of the laser can be incident on the light homogenizing device 33, avoiding the loss of light collection efficiency and improving the utilization rate of the laser.
[0087] Figure 8 The figure is a schematic structural diagram of a laser projector when the converging device provided in the embodiment of the present application is a curved lens. Refer to Figure 8 As shown, in some embodiments, the laser projector further includes a second diffusing element 37. The second diffusing element 37 is located between the converging device 32 and the light homogenizing device 33, and is used for homogenizing the laser converged by the converging device 32 to reduce speckle.
[0088] To further reduce the speckle of the system, that is, the laser projector, a second diffusing element 37 can be added in front of the light inlet of the light homogenizing device 33. Among them, the second diffusing element 37 can be a diffusing sheet, or a diffusing wheel, or other homogenizing devices that can reduce speckle. At this time, based on the diffusion surface included in the converging device 32 and the second diffusing element 34, the laser emitted by the laser device 31 can be subjected to three times of light homogenization processing before being incident on the light homogenizing device 33, effectively reducing the speckle.
[0089] Figure 8 The converging device 32 shown is a curved lens. In another implementation scenario, when the converging device 32 includes two devices, namely a curved mirror 322 and a diffuser sheet, or includes a curved mirror 322 and a diffuser wheel, a second diffusing element 37 can also be added in front of the light homogenizing device 33. Please refer to Figure 9 and Figure 10 respectively. Among them, Figure 9 FIG. Figure 10 is a schematic structural diagram of a laser projector when a converging device provided by an embodiment of the present application includes a curved mirror and a diffuser sheet.
[0090] In some embodiments, the laser projector further includes an illumination lens 38, which is located between the light homogenizing device 33 and the prism assembly 34 and is used for shaping and homogenizing the light beam emitted by the light homogenizing device 33.
[0091] Among them, the illumination lens 38 can be a single lens or an illumination lens group including multiple lenses.
[0092] In one implementation scenario, if the light valve modulation device 35 is a liquid crystal on silicon (LCOS) or a liquid crystal display (LCD), the prism assembly 34 is a polarization beam splitter prism for separating lasers with different polarization directions.
[0093] When the light valve modulation device 35 is an LCOS or an LCD, since it requires the incident light beam to have a consistent polarization direction, the prism assembly 34 needs to be a polarization beam splitter prism for separating lasers with different polarization directions. Generally, the polarization beam splitter prism can reflect the S-polarized light and transmit the P-polarized light.
[0094] Taking the light homogenizing device 33 as a light guide tube and the light valve modulation device 35 as an LCOS as an example, the light beam emitted from the light guide tube can enter the polarization beam splitter prism through the illumination lens 38. The polarization beam splitter prism reflects the S-polarized light and transmits the P-polarized light. Then the incident light beam is reflected by the polarization beam splitter prism to the LCOS. The LCOS modulates the incident S-polarized light into P-polarized light and reflects it back to the polarization beam splitter prism, and then exits from the polarization beam splitter prism to the projection lens and is projected onto the screen.
[0095] If the light valve modulation device 35 is an LCOS or an LCD, in one implementation scenario, the polarization directions of the lasers emitted by the laser 31 are different. The laser projector further includes: a phase retardation device 39;
[0096] The phase retardation device 39 is located between the laser 31 and the converging device 32 and is used for adjusting the polarization direction of the laser emitted by the laser 31 to obtain lasers with a consistent polarization direction.
[0097] In an implementation scenario, when the laser 31 is a three-color laser, that is, the laser 31 can emit red, green, and blue lasers. At this time, since the polarization directions of the above three-color lasers are inconsistent, generally, the green laser and the blue laser are S-polarized light, and the red light is P-polarized light. Therefore, a phase retardation device 39 can be placed at the position of the red light to modulate the P-polarized light into S-polarized light.
[0098] Among them, the phase retardation device 39 can be a wave plate. Specifically, a 1 / 2λ wave plate can be placed at the position of the red light to change the polarization direction of the red light.
[0099] In some embodiments, if the light valve modulation device 35 is a digital micromirror device, the prism assembly 34 is a total reflection prism.
[0100] Among them, the total reflection prism can totally reflect the light beam incident from the illumination lens 38 to the digital micromirror device, and the digital micromirror device reflects the light beam back into the total reflection prism, and the light beam can enter the projection lens through the total reflection prism.
[0101] The digital micromirror device, that is, the DMD, can include a plurality of tiny mirrors. Under the drive of current, the tiny mirrors flip within a certain angle range to adjust the light intensity entering the projection lens 36, so as to make the image present different colors.
[0102] In summary, by adding a second diffusion element 37 again before the light homogenizing device 33, the light homogenizing and speckle dissipation effects are further improved. At the same time, by arranging the illumination lens 38 between the light homogenizing device 33 and the prism assembly 34, the shaping and homogenization processing of the light beam emitted by the light homogenizing device 33 can be realized, which is beneficial to improving the display effect.
[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
[0104] For the sake of convenience of explanation, the above description has been made in combination with specific implementation manners. However, the above exemplary discussions are not intended to be exhaustive or to limit the implementation manners to the specific forms disclosed above. According to the above teachings, various modifications and deformations can be obtained. The selection and description of the above implementation manners are for better explaining the principles and actual applications, so that those skilled in the art can better use the implementation manners and various different deformed implementation manners suitable for specific use considerations.
Claims
1. A laser projector, characterized in that, Comprising: A laser for emitting laser light; A converging device, which is obliquely placed between the light-emitting side of the laser and the light-incident side of the light homogenizing device, and includes a diffusing surface and a reflecting surface. The reflecting surface is used to reflect and converge the laser light, and the diffusing surface is used to homogenize the laser light emitted by the laser and the light beam reflected by the reflecting surface to reduce speckle; The light homogenizing device is located on the light-emitting side of the converging device and is used to homogenize the converged laser light so that the processed laser light is emitted to the projection lens through the prism assembly and the light valve modulation device.
2. The laser projector according to claim 1, wherein The converging device is a curved lens, and the curved lens includes a first surface and a second surface; The first surface is a plane, serving as the diffusing surface, located on the side close to the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to homogenize the laser light to reduce speckle; The second surface is a curved surface, serving as the reflecting surface, located on the side far from the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to reflect the laser light passing through the first surface so that the laser light exits through the first surface and converges to the light homogenizing device.
3. The laser projector according to claim 1, characterized in that, The converging device includes a curved mirror and a first diffusing element; The first diffusing element includes the diffusing surface, located on the side close to the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to homogenize the laser light to reduce speckle; The curved mirror includes the reflecting surface, located on the side far from the light-emitting side of the laser and the light-incident side of the light homogenizing device, and is used to reflect the laser light passing through the first diffusing element so that the laser light exits through the first diffusing element and converges to the light homogenizing device.
4. The laser projector according to any one of claims 1-3, characterized in that, The upper limit value of the diffusion angle of the diffusing surface is 10°, and the lower limit value is 1°. Alternatively, the upper limit value of the diffusion angle is 1°, and the lower limit value is 0.1°.
5. The laser projector according to claim 1, wherein The light homogenizing device is located at the focal point of the converging device.
6. The laser projector according to claim 1, wherein The tilting angle of the converging device is determined based on the optical axis of the converged laser light and the optical axis of the light homogenizing device so that the laser light is perpendicularly incident on the light homogenizing device.
7. The laser projector according to claim 6, wherein The upper limit value of the tilting angle of the converging device is 50°, and the lower limit value is 40°.
8. The laser projector according to claim 1, wherein The laser projector further includes a second diffusing element, which is located between the converging device and the light homogenizing device and is used to homogenize the laser light converged by the converging device to reduce speckle.
9. The laser projector according to claim 1, characterized in that, If the light valve modulation device is a silicon-based liquid crystal or a liquid crystal display, the prism assembly is a polarization beam splitter prism for separating laser light with different polarization directions.
10. The laser projector according to claim 9, wherein, The polarization directions of the laser light emitted by the laser are different, and the laser projector further includes: a phase retardation device; The phase retardation device is located between the laser and the converging device and is used to adjust the polarization direction of the laser light emitted by the laser to obtain laser light with the same polarization direction.