Laser projector
By using a total reflective prism integrated illumination lens and TIR prism in the laser projector, the large size and poor portability caused by excessive optical path length are solved, and the miniaturization and portability of the laser projector are achieved.
Patent Information
- Application Number
- CN202410030447.7
- 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
In a laser projector, the laser beam passes through a large number of optical devices and the optical path size is longer, resulting in a larger projector size and poor portability.
The laser beam is fully reflected by a total reflection prism, and an integrated illumination lens and TIR prism are used to shorten the optical path length and reduce the number of optical devices.
It effectively shortens the optical path length of the laser projector, reduces the volume and improves portability.
Smart Images
Figure CN120276198A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to laser projection technology. More specifically, it relates to a laser projector. Background Art
[0002] A laser projector is a projection display device that uses laser beams to project images. Since the laser projector uses a laser light source, it has the advantages of stable performance, high brightness, and high color restoration degree of the image, and can be applied to various application scenarios.
[0003] In some related technologies, the laser emitted by the laser in the laser projector passes through a diffuser and a reflector, and then enters a converging lens. After passing through the converging lens, it enters the light guide at a certain angle, and then enters the TIR (Total Internal Reflection prism) after passing through the illumination lens or the illumination lens group. The laser beam is reflected by the inclined surface of the prism at a certain angle to the DMD (Digital Micromirror Device). The DMD microlens deflects a certain angle and reflects the light beam back into the TIR. The light beam passes through the TIR to the lens and then is projected onto the screen.
[0004] In related technologies, since the optical path size from the laser to the lens is long, the volume of the projector is large and the portability is poor. Summary of the Invention
[0005] The embodiments of the present application provide a laser projector to solve the problem in related technologies that the number of optical devices through which the laser beam passes is large and the optical path size is long, resulting in a large volume and poor portability of the projector.
[0006] In a first aspect, the embodiments of the present application provide a laser projector, which includes:
[0007] A laser for emitting a laser beam;
[0008] A light homogenizing element located on the light-emitting side of the laser for homogenizing the laser beam;
[0009] A total internal reflection prism located on the light-emitting side of the light homogenizing element, including a first prism. The first prism includes at least one curved surface and a total reflection surface, and is used to receive the laser beam emitted by the light homogenizing element and incident the laser beam on the light valve modulation device;
[0010] The light valve modulation device is used to reflect the laser beam to the total internal reflection prism so that the laser beam is emitted to the projection lens through the total internal reflection prism.
[0011] In some embodiments of the present application, the first prism includes an incident surface lens and an exit surface lens, and the curved surface of the first prism includes the curved surface of the incident surface lens and the curved surface of the exit surface lens.
[0012] In some embodiments of the present application, the distance from the light homogenizing element to the principal plane of the combined lens group is equal to the distance from the light valve modulation device to the principal plane of the combined lens group, and the distance is the combined focal length of the combined lens group;
[0013] Wherein, the combined lens group is a lens group composed of an incident surface lens and an exit surface lens.
[0014] In some embodiments of the present application, the combined focal length is determined based on the focal length of the incident surface lens, the focal length of the exit surface lens, and the distance between the principal plane of the incident surface lens and the principal plane of the exit surface lens.
[0015] In some embodiments of the present application, the first prism includes an exit surface lens, the curved surface of the first prism is the curved surface of the exit surface lens, and the incident surface of the first prism is a plane.
[0016] In some embodiments of the present application, the optical path from the light homogenizing element to the curved surface of the exit surface lens is equal to the optical path from the light valve modulation device to the curved surface of the exit surface lens.
[0017] In some embodiments of the present application, the first prism includes an incident surface lens, the curved surface of the first prism is the curved surface of the incident surface lens, and the exit surface of the first prism is a plane.
[0018] In some embodiments of the present application, the upper limit value of the tilt angle of the total reflection surface is 70°, and the lower limit value of the tilt angle is 20°.
[0019] In some embodiments of the present application, the total reflection prism further includes a second prism, and the exit surface of the second prism is a plane or a curved surface.
[0020] In some embodiments of the present application, the laser projector further includes: a homogenizing element, which is located between the laser and the light homogenizing element and is used to reduce the speckle of the laser projector.
[0021] The present application provides a laser projector, which includes a laser, a light homogenizing element, a total reflection prism, a light valve modulation device, and a projection lens. Among them, the total reflection prism includes a first prism, and the first prism includes at least one curved surface and a total reflection surface. The laser beam emitted by the laser is incident on the light homogenizing element. The light homogenizing element performs light homogenizing processing on the laser beam and emits the beam to the total reflection prism. The beam is reflected by the total reflection prism to the light valve modulation device to obtain a uniform light spot. The beam is reflected back to the total reflection prism after passing through the light valve modulation device, and the beam exits from the total reflection prism to the projection lens and is projected onto the screen through the projection lens to achieve projection. In the total reflection prism of the present application, the first prism includes at least one curved surface, that is, the illumination lens or illumination lens group in the related art is integrated on the total reflection prism. The beam emitted from the light homogenizing element can be directly incident on the total reflection prism, effectively shortening the distance between the light homogenizing element and the total reflection prism, shortening the optical path, which is beneficial to reducing the volume of the laser projector and thus improving portability. At the same time, the present application also does not require devices such as a reflecting mirror and a converging lens, reducing the number of optical devices used. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] 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 for use 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.
[0023] Figure 1 Schematic diagram of a projector in a related art;
[0024] Figure 2 Schematic diagram of a laser projector provided by an embodiment of the present application;
[0025] Figure 3 Schematic structural diagram of a laser projector provided by an embodiment of the present application;
[0026] Figure 4 Schematic structural diagram of a laser projector provided by an embodiment of the present application, where the incident surface and the exit surface of the first prism are both curved surfaces and the exit surface of the second prism is a curved surface;
[0027] Figure 5 Schematic diagram of the optical path transmission from a compound eye lens to a DMD provided by an embodiment of the present application;
[0028] Figure 6 Optical path schematic diagram based on compound eye lens imaging;
[0029] Figure 7 Schematic diagram of the positional relationship between a light homogenizing element, a combined lens group, and a light valve modulation device provided by an embodiment of the present application;
[0030] Figure 8 Schematic diagram of a laser projector provided by an embodiment of the present application, in which the incident surface of a first prism is a plane, the exit surface is a curved surface, and the exit surface of a second prism is a plane;
[0031] Figure 9 Schematic diagram of a laser projector provided by an embodiment of the present application, in which the incident surface of a first prism is a plane, the exit surface is a curved surface, and the exit surface of a second prism is a curved surface;
[0032] Figure 10 Schematic diagram of a laser projector provided by an embodiment of the present application, in which the incident surface of a first prism is a curved surface, the exit surface is a plane, and the exit surface of a second prism is a plane;
[0033] Figure 11 Schematic diagram of a laser projector provided by an embodiment of the present application, in which the incident surface of a first prism is a curved surface, the exit surface is a plane, and the exit surface of a second prism is a curved surface. Detailed implementation manners
[0034] 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 of the embodiments of the present application, rather than all of the embodiments.
[0035] 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.
[0036] In addition, the terms "include" and "have" and any variations thereof are intended to cover but not be exclusive of inclusion. For example, a product or device including a series of components does not necessarily have to be limited to those clearly listed components, but may include other components not clearly listed or inherent to these products or devices.
[0037] Figure 1 Schematic diagram of a projector in a related art. As Figure 1As shown, the RGB three-color lasers emitted by the laser pass through the diffuser and the reflector, and are incident on the converging lens. After passing through the converging lens, they are incident on the light guide tube at a certain angle. To weaken the speckle effect of the system, generally a diffuser or a diffuser wheel needs to be placed at the entrance of the light guide tube. After the inner wall of the light guide tube reflects the light beam multiple times, a spot with a relatively high uniformity is formed at the exit. After passing through the illumination lens (group), it enters the TIR prism, and is reflected by the inclined surface of the TIR prism at a certain angle to the DMD. The microlens of the DMD deflects a certain angle, reflects the light beam back into the TIR prism, and the light beam passes through the TIR prism to the lens and then projects onto the screen. The optical path size is relatively long, resulting in a relatively large volume of the projector and poor portability. At the same time, a relatively large number of optical devices are used.
[0038] Among them, the illumination lens (group) refers to an illumination lens or an illumination lens group, and the illumination lens group is composed of multiple lenses.
[0039] Since, to ensure the homogenization and imaging effects, the light guide tube and the DMD can be located at the focal point of the illumination lens (group), the optical path can be shortened by reducing the focal length of the illumination lens (group), thereby reducing the volume of the projector. However, due to the certain thickness of the TIR prism, there is a minimum threshold for the focal length of the illumination lens (group), resulting in a certain distance between the illumination lens (group) and the DMD, and the distance from the light guide tube to the illumination lens cannot be reduced either. Therefore, shortening the optical path and reducing the volume by reducing the focal length of the illumination lens (group) cannot achieve miniaturization to the greatest extent.
[0040] Based on this, the present application provides a laser projector. In the related art, usually the illumination lens (group) and the TIR prism are designed separately, and the TIR prism is divided into two prisms, and the surfaces of the prisms are all flat surfaces. To shorten the optical path, the surface of the TIR prism can be set as a curved surface, that is, by integrating the lens onto the TIR prism, replacing the traditional system of a lens plus a TIR prism, shortening the size of the illumination optical path, further reducing the volume of the laser projector, improving the portability, and at the same time eliminating the need for optical devices such as reflectors and converging lenses, reducing the optical devices, and optimizing the system structure.
[0041] The laser projector of the present application relates to laser projection technology and also relates to the field of optoelectronic technology. The present application does not limit this.
[0042] Figure 2 It is a schematic diagram of a laser projector provided by an embodiment of the present application. The laser projector can also be called a laser projection device, a laser projector, etc. As Figure 2As shown in the figure, the laser projector may include: a light source 201, an optical engine 202, and a lens 203. Among them, the light source 201 is used to provide a laser beam, which is transmitted to the lens 203 through the optical engine 202 for imaging. The light source 201 may include lasers of at least one color, and may be a single-color laser, a two-color laser, or a three-color laser, etc.
[0043] The laser beam provided by the light source 201 is incident on the illumination optical path part in the optical engine 202 after combining and shaping the light. The optical engine 202 contains optical devices of the illumination optical path, including a light homogenizing element, a total reflection prism, a light valve modulation device, etc.
[0044] In the DLP (Digital Light Processing) projection architecture, the DMD (Digital Micromirror Device) is the core light valve modulation device. The DMD can receive the drive control signal corresponding to the image signal, flip the multiple micro mirrors on its surface at a positive or negative angle corresponding to the drive signal, reflect the light beam irradiating its surface into the total reflection prism, and then be incident into the lens 203.
[0045] The lens 203 can be an ultra-short throw projection lens, which is used to transmit the image light beam to the projection screen, so as to realize the projection image display. The laser projector in the above example can be an ultra-short throw laser projector.
[0046] The technical solution of the present application will be described in detail below with reference to 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. The embodiments of the present application will be described below with reference to the accompanying drawings.
[0047] Figure 3 The structural schematic diagram of a laser projector provided by an embodiment of the present application is as Figure 3 shown, the laser projector may include:
[0048] A laser 10, which is used to emit a laser beam;
[0049] A light homogenizing element 20, which is located on the light emitting side of the laser 10 and is used to perform light homogenizing processing on the laser beam;
[0050] A total reflection prism 30, which is located on the light emitting side of the light homogenizing element 20 and includes a first prism. The first prism includes at least one curved surface and a total reflection surface, and is used to receive the laser beam emitted by the light homogenizing element 20 and incident the laser beam on the light valve modulation device 40;
[0051] The light valve modulation device 40 is used to reflect the laser beam to the total reflection prism 30, so as to emit the laser beam to the projection lens 50 through the total reflection prism 30.
[0052] In some embodiments, the laser 10 can be a monochromatic laser, such as a blue laser that emits a blue laser beam, or a dichromatic laser. The dichromatic laser can be a blue laser and a red laser, etc., or it can also be a trichromatic laser that can emit laser beams of red, green, and blue.
[0053] In one implementation scenario, the laser 10 can include multiple laser chips, and the laser chips can be arranged in an array. Therefore, the laser beam emitted by the laser 10 can be used as a parallel beam and incident on the light homogenizing element 20. For example, when the laser is a trichromatic laser, it includes multiple laser chips capable of emitting red, multiple green laser chips, and multiple blue laser chips, and they are arranged in a certain order. The present application does not limit the number and arrangement method of the laser chips.
[0054] In some embodiments, the first prism of the total reflection prism 30, i.e., the TIR prism, generally includes three surfaces, namely an incident light surface, an outgoing light surface, and a total reflection surface. Among them, the incident light surface is the surface of the first prism close to the light homogenizing element 20 and is used to receive the beam emitted by the light homogenizing element 20. The total reflection surface is an inclined surface used to reflect the beam passing through the incident light surface to the outgoing light surface. The outgoing light surface is the surface of the first prism close to the light valve modulation device 40 and transmits the beam to the light valve modulation device 40 to form a uniform light spot.
[0055] Among them, the light valve modulation device 40 can be a DMD (Digital Micromirror Device), an LCD (Liquid Crystal Display), or an LCOS (Liquid Crystal on Silicon). The present application does not limit this.
[0056] Taking the light valve modulation device 40 as a DMD as an example, the DMD can include multiple tiny mirrors. The tiny mirrors are flipped within a certain angle range under current drive to adjust the light entering the projection lens 50, so that the image presents different colors.
[0057] It should be noted that based on the working principles of the DMD, LCD, and LCOS, there will be certain differences in the position of the projection lens 50. In the embodiments of the present application, the light valve modulation device 40 is taken as a DMD for detailed description. Figure 3 The structure corresponding to when the light valve modulation device 40 is a DMD is shown.
[0058] At least one of the incident light surface and the emergent light surface of the TIR prism 30 is a curved surface, which can be respectively: the incident light surface is a curved surface and the emergent light surface is a plane; the incident light surface is a plane and the emergent light surface is a curved surface; both the incident light surface and the emergent light surface are curved surfaces, etc. Among them, Figure 3 The TIR prism 30 shown is the case where both the incident light surface and the emergent light surface are curved surfaces.
[0059] In one implementation scenario, the incident light surface and / or the emergent light surface being a curved surface can be achieved through a lens. The lens is integrated on the TIR prism 30, so that the incident light surface and / or the emergent light surface of the TIR prism 30 is a curved surface. Among them, the integration can be carried out by means of bonding. The integrated lens can be a convex lens. At this time, the curved surface of the incident light surface and / or the emergent light surface of the first prism is a convex surface. Or, the lens and the TIR prism 30 can also be integrally designed.
[0060] In one implementation scenario, the upper limit value of the tilt angle of the total reflection surface is 70°, and the lower limit value of the tilt angle is 20°. The total reflection surface is a plane, and its tilt angle is the included angle between this plane and the horizontal plane.
[0061] The light homogenizing element 20 is a device capable of homogenizing the laser beam, including but not limited to elements such as a compound eye lens and a light pipe. Among them, the compound eye lens is composed of a series of small lenses. Specifically, it can be a double-row compound eye lens array.
[0062] In some embodiments, the laser projector further includes: a homogenizing element, which is located between the laser 10 and the light homogenizing element 20 and is used to reduce the speckle of the laser projector.
[0063] The homogenizing element includes but not limited to devices such as a diffuser sheet and a diffuser wheel, which weaken the speckle effect of the laser projector, thereby improving the display effect.
[0064] In some embodiments, the total reflection prism further includes a second prism, and the emergent light surface of the second prism is a plane or a curved surface.
[0065] The emergent light surface of the second prism is the surface close to the projection lens 50. In one implementation scenario, when the light valve modulation device 40 is a DMD, the beam reflected by the DMD passes through the emergent light surface and the total reflection surface of the first prism and is incident on the second prism, and exits from the emergent light surface of the second prism to the projection lens 50.
[0066] The emergent light surface of the second prism being a curved surface can also be achieved through a lens. The lens integrated on the emergent light surface of the second prism can be used as an imaging lens of the projection lens 50, increasing an aberration correction degree of freedom, which is beneficial to aberration correction, thereby improving the imaging effect and enhancing the user experience.
[0067] An embodiment of the present application provides a laser projector, which includes a laser 10, a light homogenizing element 20, a TIR prism 30, a light valve modulation device 40, and a projection lens 50. Among them, the TIR prism 30 includes a first prism, and the first prism includes at least one curved surface and a total reflection surface. The laser beam emitted by the laser 10 is incident on the light homogenizing element 20. The light homogenizing element 20 performs light homogenization processing on the laser beam and emits the beam to the TIR prism 30. The beam is reflected by the TIR prism 30 onto the light valve modulation device 40 to obtain a uniform light spot. The beam is reflected back into the TIR prism 30 by the light valve modulation device 40 and projected onto the screen through the projection lens 50 to achieve projection. In the present application, the illumination lens or illumination transparent group in the related art is integrated on the TIR prism 30. The beam emitted from the light homogenizing element 20 can be directly incident on the TIR prism 30 without passing through the illumination lens (group) and the TIR prism in sequence, shortening the distance between the light homogenizing element 20 and the TIR prism 30. Therefore, the optical path is shortened, the volume of the projector is reduced, which is beneficial to improving portability. At the same time, the present application also does not require devices such as a reflector and a converging lens, so the number of optical devices used is reduced.
[0068] In one or more embodiments of the present application, the first prism includes an incident surface lens and an exit surface lens, and the curved surface of the first prism includes the curved surface of the incident surface lens and the curved surface of the exit surface lens.
[0069] When both the incident surface and the exit surface of the first prism are curved surfaces, the exit surface of the second prism can be a flat surface or a curved surface, where Figure 3 the shown exit surface of the second prism is a flat surface.
[0070] Figure 4 is a schematic structural diagram of a laser projector in which the incident surface and the exit surface of a first prism provided by an embodiment of the present application are both curved surfaces and the exit surface of a second prism is a curved surface. Figure 4 The relative positional relationship among the laser 10, the light homogenizing element 20, the TIR prism 30, the light valve modulation device 40, and the projection lens 50 in Figure 3 is the same, and will not be described in detail here. Figure 4 A homogenizing element 60 included in the laser projector is shown between the laser 10 and the light homogenizing element 20. At the same time, for the first prism included in the TIR prism, L1 represents the incident surface lens of the first prism, and L2 represents the exit surface lens of the first prism.
[0071] Figure 5 is a schematic diagram of the optical path transmission from a compound eye lens to a DMD provided by an embodiment of the present application. Combining Figure 4 and Figure 5As shown, when the light homogenizing element 20 is a fly-eye lens and the homogenizing element 60 is a diffuser, the laser beam emitted by the laser 10 irradiates the fly-eye lens through the diffuser, and a light spot array is formed on the rear surface of the fly-eye lens, that is, the beam is divided into multiple point light sources by the fly-eye lens. The beam emitted from the second microlens surface of the fly-eye lens irradiates the TIR prism 30, enters the total reflection surface of the TIR prism 30 through the curved surface of the incident light lens L1, is reflected to the outgoing light lens L2, and after passing through the curved surface of the outgoing light lens L2, a spot with higher uniformity is formed on the DMD.
[0072] After the micromirror on the DMD rotates by a certain angle, the beam is reflected back into the TIR prism 30. After being converged by the curved surface of the first prism outgoing light lens L2, it is transmitted to the second prism and projected from the outgoing light surface of the second prism to the projection lens 50, and then projected onto the screen through the projection lens 50 to achieve projection.
[0073] Figure 6 It is a schematic optical path diagram based on the imaging of a fly-eye lens. As Figure 6 shown, the beam emitted by the light source passes through the collimating mirror to obtain a parallel beam. After the parallel beam is incident on the fly-eye lens for light homogenization processing, it forms an image on the target illumination surface through the integrating lens. According to the working principle of the fly-eye lens, the optical path from the fly-eye lens to the integrating lens and from the integrating lens to the target illumination surface is equal.
[0074] Based on the above working principle of the fly-eye lens, in an implementation scenario, the distance from the light homogenizing element 20 to the principal plane of the combined lens group is equal to the distance from the light valve modulation device 40 to the principal plane of the combined lens group, and the distance is the combined focal length of the combined lens group;
[0075] Among them, the combined lens group is a lens group composed of the incident light lens L1 and the outgoing light lens L2.
[0076] Let the distance from the light homogenizing element 20 to the principal plane of the combined lens group be d1, and the distance from the light valve modulation device 40 to the principal plane of the combined lens group be d2, then d1 = d2 = |f|, where f represents the combined focal length of the combined lens group.
[0077] At this time, the light homogenizing element 20 and the light valve modulation device 40 are respectively located at the positions corresponding to the combined focal points of the combined lens group to ensure the homogenization and imaging effects.
[0078] Since the distance from the light homogenizing element 20 to the principal plane of the combined lens group is the combined focal length and the distance from the light valve modulation device 40 to the principal plane of the combined lens group is the combined focal length, when the combined focal length is the smallest, the distance from the light homogenizing element 20 to the light valve modulation device 40 is the shortest, so as to minimize the volume of the laser projector to the greatest extent.
[0079] In an implementation scenario, the combined focal length is determined based on the focal length of the incident light surface lens L1, the focal length of the outgoing light surface lens L2, and the distance between the principal plane of the incident light surface lens L1 and the principal plane of the outgoing light surface lens L2.
[0080] In an implementation scenario, a calculation method for the combined focal length can be:
[0081] 1 / f = 1 / f1 + 1 / f2 - d / (f1*f2) (1)
[0082] Based on the derivation of the above formula (1), f = f1*f2 / (f1 + f2 - d) can be obtained, where f represents the combined focal length of the combined lens group, f1 is the focal length of the incident light surface lens L1, f2 is the focal length of the outgoing light surface lens L2, and d represents the distance between the principal plane of the incident light surface lens L1 and the principal plane of the outgoing light surface lens L2.
[0083] In some embodiments, Figure 7 This is a schematic diagram of the positional relationship among a light homogenizing element, a combined lens group, and a light valve modulation device provided in the embodiments of the present application. Refer to Figure 7 As shown, the combined lens group includes an incident light surface lens L1 and an outgoing light surface lens L2. The plane perpendicular to the optical axis of the straight line l between the incident light surface lens L1 and the outgoing light surface lens L2 is the principal plane of the combined lens group. d1 is the distance from the light homogenizing element to the principal plane of the combined lens group, d2 is the distance from the light valve modulation device to the principal plane of the combined lens group, and d1 = d2 = |f|, where f is the focal length of the combined lens group.
[0084] d1' is the distance from the incident light surface of the first prism to the principal plane of the combined lens group, and d2' is the distance from the outgoing light surface of the first prism to the principal plane of the combined lens group. Generally, the light valve modulation device 40 is closer to the outgoing light surface of the first prism. It is only necessary to ensure that the position of the principal plane of the combined lens group is close to the distance from the outgoing light surface of the first prism to the combined focal length f, so that the distance from the light valve modulation device 40 to the surface of the outgoing light surface lens L2 is the shortest, minimizing the optical path and reducing the volume of the laser projector.
[0085] In some embodiments, the first prism includes the outgoing light surface lens L2. The curved surface of the first prism is the curved surface of the outgoing light surface lens L2, and the incident light surface of the first prism is a plane. Specifically, reference can be made to Figure 8 and Figure 9 As shown.
[0086] Among them, Figure 8 This is a schematic diagram of a laser projector provided in the embodiments of the present application, in which the incident light surface of the first prism is a plane, the outgoing light surface is a curved surface, and the outgoing light surface of the second prism is a plane. Figure 9Schematic diagram of a laser projector provided by an embodiment of the present application, where the incident surface of a first prism is a plane, the exit surface is a curved surface, and the exit surface of a second prism is a curved surface. When the incident surface of the first prism is a plane and the exit surface is a curved surface, the exit surface of the second prism can be a plane or a curved surface.
[0087] Figure 8 and Figure 9 Also shown are a laser 10, a homogenizing element 60, a light homogenizing element 20, a TIR prism 30, a light valve modulation device 40, and a projection lens 50. Their relative positions are the same as those in the above embodiment, and will not be elaborated here in the present application.
[0088] In some embodiments, when the incident surface of the first prism is a plane, it can be considered that the focal length of the incident surface lens L1 of the first prism is infinite. Therefore, there is also a corresponding combined focal length, and the combined focal length can also be calculated by the formula (1) provided above.
[0089] Based on the above formula (1), since the focal length f1 of the incident surface lens L1 is infinite, 1 / f1 is approximately 0, and d / (f1*f2) is also approximately 0. It can be obtained that 1 / f = 1 / f2, that is, f = f2. Where f1 is the focal length of the incident surface lens L1, f2 is the focal length of the exit surface lens L2, and d represents the distance between the principal plane of the incident surface lens L1 and the principal plane of the exit surface lens L2. Therefore, it can be known that the current combined focal length f is the focal length f2 of the exit surface lens L2.
[0090] In one implementation scenario, the optical path from the light homogenizing element 20 to the curved surface of the exit surface lens L2 is equal to the optical path from the light valve modulation device 40 to the curved surface of the exit surface lens L2.
[0091] When the optical path from the light homogenizing element 20 to the curved surface of the exit surface lens L2 is equal to the optical path from the light valve modulation device 40 to the curved surface of the exit surface lens L2, the light homogenizing element 20 and the light valve modulation device 40 can be arranged at the focal point of the exit surface lens L2.
[0092] In one implementation scenario, when the exit surface of the first prism is a curved surface, the illumination lens can be integrated with the first prism of the exit surface lens L2 and the TIR prism 30, shortening the distance from the illumination lens to the light valve modulation device 40. Since the optical path from the light homogenizing element 20 to the curved surface of the exit surface lens L2 is equal to the optical path from the light valve modulation device 40 to the curved surface of the exit surface lens L2, the distance from the light homogenizing element 20 to the illumination lens is also shortened, that is, the distance from the light homogenizing element 20 to the TIR prism 30 is shortened, thereby shortening the optical path, which is beneficial to reducing the volume of the laser projector and improving portability.
[0093] In some embodiments, the first prism includes an incident surface lens L1. The curved surface of the first prism is the curved surface of the incident surface lens L1, and the exit surface of the first prism is a plane. For details, reference can be made to Figure 10and Figure 11 as shown
[0094] Figure 10 Schematic diagram of a laser projector provided by an embodiment of the present application, where the incident surface of the first prism is a curved surface, the exit surface is a plane, and the exit surface of the second prism is a plane Figure 11 Schematic diagram of a laser projector provided by an embodiment of the present application, where the incident surface of the first prism is a curved surface, the exit surface is a plane, and the exit surface of the second prism is a curved surface
[0095] When the incident surface of the first prism is a curved surface and the exit surface is a plane, the exit surface of the second prism can be a plane. Refer to Figure 10 as shown, the exit surface of the second prism can also be a curved surface. Refer to Figure 11 as shown
[0096] Since the exit surface of the first prism is a plane, the focal length of the exit surface lens L2 of the first prism can be regarded as infinite. Therefore, there is also a corresponding combined focal length, and the combined focal length can also be calculated by the formula (1) provided above
[0097] Based on formula (1), since the focal length f2 of the exit surface lens L2 is infinite, 1 / f2 is approximately 0, and d / (f1*f2) is also approximately 0. It can be obtained that 1 / f = 1 / f1, that is, f = f1. Where f1 is the focal length of the incident surface lens L1, f2 is the focal length of the exit surface lens L2, and d represents the distance between the principal plane of the incident surface lens L1 and the principal plane of the exit surface lens L2. Therefore, the current combined focal length f is the focal length f1 of the incident surface lens L1
[0098] In one implementation scenario, to ensure the homogenization and imaging effects, the homogenizing element 20 and the light valve modulation device 40 can be arranged at the focal point of the incident surface lens L1
[0099] In one implementation scenario, the incident surface of the first prism is a curved surface, and the illumination lens can be integrated with the incident surface of the TIR prism as the incident surface lens L1, so that the illumination lens is close to the light valve modulation device 40, and the distance between the illumination lens and the light valve modulation device 40 is reduced, thereby reducing the distance between the homogenizing element 20 and the illumination lens and reducing the volume
[0100] It should be noted that the incident surface lens L1, or the exit surface lens L2, or the incident surface lens L1 and the exit surface lens L2 included in the first prism is equivalent to the illumination lens or the illumination lens group in the related art. The illumination lens or the illumination lens group is integrated with the TIR prism, so that the first prism includes at least one curved surface, and a special-shaped TIR prism is obtained to shorten the distance between the homogenizing element 20 and the light valve modulation device 40, thereby shortening the optical path and reducing the volume of the laser projector
[0101] However, for the light-emitting surface of the second prism being a curved surface, that is, a lens is integrated on the light-emitting surface of the second prism, and this lens serves as an imaging lens of the projection lens 50 for aberration correction. Therefore, whether a lens is integrated on the light-incident surface and the light-emitting surface of the first prism does not affect the integration of the lens on the light-emitting surface of the second prism. Similarly, whether a lens is integrated on the light-emitting surface of the second prism also does not affect whether a lens is integrated on the light-incident surface and the light-emitting surface of the first prism.
[0102] In an implementation scenario, the light-incident surface and the light-emitting surface of the first prism can also be both flat surfaces, and integrating a lens on the light-emitting surface of the second prism can also be used for aberration correction.
[0103] In summary, setting both the light-incident surface and the light-emitting surface of the TIR prism 30 as curved surfaces, or the light-emitting surface as a curved surface and the light-incident surface as a flat surface, or the light-incident surface as a curved surface and the light-emitting surface as a flat surface realizes the combination of the illumination lens and the TIR prism 30. Compared with the related art where the light homogenizing element 20 and the TIR prism 30 are located at the focal points on both sides of the illumination lens, integrating the illumination lens on the TIR prism 30 effectively shortens the distance between the light homogenizing element 20 and the TIR prism 30, thereby shortening the size of the optical path, which is beneficial to reducing the volume of the laser projector and improving portability.
[0104] 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 it; 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.
[0105] For the sake of convenience of explanation, the above description has been made in combination with specific implementation manners. However, the above exemplary discussion is 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 variations can be obtained. The selection and description of the above implementation manners are for better explaining the principles and practical applications, so that those skilled in the art can better use the implementation manners and the various different variant implementation manners suitable for specific use considerations.
Claims
1. A laser projector, characterized in that, The laser projector includes: a laser for emitting a laser beam; a light homogenizing element located on the light-emitting side of the laser for homogenizing the laser beam; a total reflection prism located on the light-emitting side of the light homogenizing element, including a first prism, the first prism including at least one curved surface and a total reflection surface, for receiving the laser beam emitted from the light homogenizing element and incidenting the laser beam onto a light valve modulation device; the light valve modulation device is configured to reflect the laser beam to the total reflection prism, so as to emit the laser beam to a projection lens through the total reflection prism.
2. The laser projector according to claim 1, wherein, The first prism includes an incident surface lens and an exit surface lens, and the curved surface of the first prism includes the curved surface of the incident surface lens and the curved surface of the exit surface lens.
3. The laser projector according to claim 2, characterized in that, The distance from the light homogenizing element to the principal plane of the combined lens group is equal to the distance from the light valve modulation device to the principal plane of the combined lens group, and this distance is the combined focal length of the combined lens group; wherein, the combined lens group is a lens group composed of the incident surface lens and the exit surface lens.
4. The laser projector according to claim 3, wherein The combined focal length is determined based on the focal length of the incident surface lens, the focal length of the exit surface lens, and the distance between the principal plane of the incident surface lens and the principal plane of the exit surface lens.
5. The laser projector according to claim 1, wherein, The first prism includes an exit surface lens, the curved surface of the first prism is the curved surface of the exit surface lens, and the incident surface of the first prism is a plane.
6. The laser projector according to claim 5, wherein, The optical path from the light homogenizing element to the curved surface of the exit surface lens is equal to the optical path from the light valve modulation device to the curved surface of the exit surface lens.
7. The laser projector according to claim 1, wherein The first prism includes an incident surface lens, the curved surface of the first prism is the curved surface of the incident surface lens, and the exit surface of the first prism is a plane.
8. The laser projector according to claim 1, characterized in that, The upper limit value of the tilt angle of the total reflection surface is 70°, and the lower limit value of the tilt angle is 20°.
9. The laser projector according to any one of claims 1-8, characterized in that, The total reflection prism further includes a second prism, and the exit surface of the second prism is a plane or a curved surface.
10. The laser projector according to claim 1, characterized in that, The laser projector further includes: a homogenizing element located between the laser and the light homogenizing element for reducing the speckle of the laser projector.