Projection lens and laser projection equipment

Abstract

The embodiment of the utility model belongs to the photoelectric technology, and provides a projection lens and laser projection equipment, and the projection lens comprises a polarization reflection device which is used for transmitting an imaging light beam and reflecting first stray light based on the polarization direction of the imaging light beam, or reflecting the imaging light beam and transmitting the first stray light; the polarization reflection device is plated with an angle selection film layer, and the angle selection film layer is used for transmitting the imaging light beam and reflecting the second stray light or reflecting the imaging light beam and transmitting the second stray light based on the angle range of the imaging light beam incident to the polarization reflection device; the first stray light is a light beam which is not modulated by the light valve modulator and is incident to the projection lens, and the polarization direction of the first stray light is different from the polarization direction of the imaging light beam; the second stray light is stray light generated in the projection lens. According to the invention, the first stray light and the second stray light can be eliminated, and the image contrast is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to optoelectronic technology, and more particularly to a projection lens and a laser projection device. Background Art

[0002] With the development of laser projection equipment, people's requirements for the display effect of projection images are gradually increasing. Since laser projection equipment includes multiple lenses, the laser emitted by the laser will produce a certain amount of reflected light when passing through the surface of each lens. After multiple reflections, the reflected light forms a stray light environment inside the equipment. If it is not controlled, the stray light will be projected onto the screen through the projection lens, thereby reducing the contrast of the picture. At the same time, after the laser enters the projection lens, since the projection lens also includes multiple lenses, it will also form a certain amount of stray light after multiple reflections on multiple lenses and the surface of the barrel, which will also reduce the contrast of the picture.

[0003] In the related art, in order to improve the contrast, the intensity of reflected light can be reduced by increasing the transmittance of the lens surface. At the same time, light-absorbing paint is applied to the surface of the lens barrel or matte threads are provided to reduce stray light.

[0004] However, since the degree of improvement in the lens surface transmittance is limited, and the light-absorbing paint and matte thread can only reduce part of the stray light, there is still some stray light that is projected onto the screen through the projection lens, resulting in a low contrast of the picture. Utility Model Content

[0005] The embodiments of the present application provide a projection lens and a laser projection device, which can be used to solve the problem in the related art that stray light is reduced by increasing the transmittance of the lens surface, coating the lens barrel surface with light-absorbing paint or providing matte threads, but some stray light is still projected onto the screen through the projection lens, resulting in low image contrast.

[0006] In a first aspect, an embodiment of the present application provides a projection lens, wherein the projection lens comprises:

[0007] a polarization reflection device, configured to transmit the imaging light beam and reflect the first stray light based on the polarization direction of the imaging light beam, or to reflect the imaging light beam and transmit the first stray light;

[0008] The polarized reflective device is coated with an angle selection film layer, and the angle selection film layer is used to transmit the imaging light beam and reflect the second stray light based on the angle range of the imaging light beam incident on the polarized reflective device, or reflect the imaging light beam and transmit the second stray light;

[0009] The imaging light beam is a light beam incident on the projection lens after being modulated by a light valve modulation device, the first stray light is a light beam incident on the projection lens without being modulated by the light valve modulation device, and the polarization direction of the first stray light is different from the polarization direction of the imaging light beam;

[0010] The second stray light is stray light generated inside the projection lens.

[0011] In some embodiments of the present application, the angle range of the imaging light beam incident on the polarized reflective device is the sum of the divergence angle corresponding to the imaging light beam incident on the polarized reflective device and the tilt angle of the polarized reflective device, and the tilt angle is the angle between the polarized reflective device and the optical axis of the projection lens.

[0012] In some embodiments of the present application, the angle between the polarized reflective device and the optical axis of the projection lens is 45°.

[0013] In some embodiments of the present application, if the polarization reflection device is used to reflect the imaging light beam and transmit the first stray light based on the polarization direction of the imaging light beam, the projection lens further includes: a first polarization conversion device;

[0014] The first polarization conversion device is used to change the polarization direction of the imaging light beam, so that the polarization reflection device reflects the imaging light beam with the polarization direction changed.

[0015] In some embodiments of the present application, the projection lens further includes: a housing, and a region in the housing that receives the first stray light and the second stray light is a lens barrel structure or is coated with a light-absorbing material.

[0016] In a second aspect, an embodiment of the present application provides a laser projection device, which includes a laser, an illumination light path, a prism assembly, a light valve modulation device, and a projection lens as described in any one of the first aspects.

[0017] In some embodiments of the present application, the light valve modulation device is a digital micromirror device, a silicon-based liquid crystal or a liquid crystal display.

[0018] In some embodiments of the present application, if the light valve modulation device is a digital micromirror device, the laser projection device further includes a second polarization conversion device, which is located between the prism assembly and the light valve modulation device and is used to change the polarization direction of the imaging light beam.

[0019] In some embodiments of the present application, the illumination light path includes a homogenization device, an illumination lens group, and a polarizer;

[0020] The homogenizing device is used to homogenize the laser light emitted by the laser;

[0021] The illumination mirror group is located at the light output side of the homogenizing device and is used to shape the laser;

[0022] The polarizer is located between the lighting lens assembly and the prism assembly, and is used to transmit light in a target polarization direction and filter out light in other polarization directions except the target polarization direction.

[0023] In some embodiments of the present application, if the homogenizing device is a light guide, the illumination optical path further includes a converging reflective device located at the light output side of the laser, for reflecting the laser light emitted by the laser and converging it onto the light guide.

[0024] The present application provides a projection lens and a laser projection device. In the projection lens of the present application, a polarized reflection device is arranged inside the projection lens, and based on the polarization direction of the imaging beam, the imaging beam is transmitted and the first stray light is reflected, or the imaging beam is reflected and the first stray light is transmitted, so that the first stray light that is not modulated by the light valve modulation device and incident on the projection lens is removed from the light path, wherein the polarization direction of the first stray light is different from that of the imaging beam, so that the first stray light is prevented from being projected onto the screen through the projection lens, which is beneficial to improving the contrast of the picture. At the same time, through the angle selection film layer coated with the polarized reflection device, based on the angle range of the imaging beam incident on the polarized reflection device, the imaging beam is transmitted and the second stray light is reflected, or the imaging beam is reflected and the second stray light is transmitted, so that the second stray light generated inside the projection lens and incident on the polarized reflection device at an angle exceeding the angle range, that is, exceeding the projection field angle, is removed from the light path, and the second stray light is prevented from being projected onto the screen through the projection lens, which is beneficial to further improving the contrast of the picture and improving the picture display quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the implementation methods in the embodiments of the present application or the related technologies, the following is a brief introduction to the drawings required for use in the embodiments or the related technology descriptions. Obviously, the drawings described below are some embodiments of the present application, and a person skilled in the art can also obtain other drawings based on these drawings.

[0026] Figure 1 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 1 ;

[0027] Figure 2 It is a structural schematic diagram of a laser projection device based on LCOS;

[0028] Figure 3 It is a structural schematic diagram of a projection lens in the related art;

[0029] Figure 4 A schematic diagram of a projection lens structure provided in an embodiment of the present application Figure 1 ;

[0030] Figure 5 A schematic diagram of a projection lens structure provided in an embodiment of the present application Figure 2 ;

[0031] Figure 6 A schematic diagram of a projection lens structure provided in an embodiment of the present application Figure 3 ;

[0032] Figure 7 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 2 ;

[0033] Figure 8 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 3 ;

[0034] Fig. 9 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 4 ;

[0035] Fig.10 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 5 . DETAILED DESCRIPTION

[0036] In order to make the purpose, implementation mode and advantages of the present application clearer, the exemplary implementation mode of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0037] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their common and usual meanings.

[0038] In addition, the terms "include" and "have" and any variations thereof are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to those components explicitly listed but may include other components not explicitly listed or inherent to such products or devices.

[0039] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0040] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0041] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] Figure 1 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 1 ,refer to Figure 1 As shown, after the upper shell of the laser projection device is disassembled, the internal structure is divided according to the optical function and may include a light source 101, an optical engine 102 and a projection lens 103.

[0044] The light source 101 is used to provide a light source illumination beam, which is transmitted to the rear optical machine 102 and the projection lens 103. The light source 101 may include a laser of at least one color, such as a blue laser, or a two-color laser, a three-color laser, etc.

[0045] The light beam provided by the light source 101 is incident on the light valve modulation device in the optical machine 102 after light combination and shaping, and after being modulated by the light valve modulation device, it can be incident on the projection lens 103. Among them, the light valve modulation device can be a DMD (Digital Micromirror Device), LCOS (Liquid Crystal On Silicon) or LCD (Liquid Crystal Display), etc.

[0046] The projection lens 103 projects the light beam onto the screen, thereby realizing projection image display.

[0047] Figure 2 This is a schematic diagram of the structure of a laser projection device based on LCOS. Figure 2 As shown, the laser projection device includes: a laser 21 , a focusing reflector 22 , a light pipe 23 , an illumination lens group 24 , a polarizer 25 , a PBS (Polarizing Beam Splitter) 26 , an LCOS 27 and a projection lens 28 .

[0048] For LCOS27, the polarization direction of the light beam incident to LCOS27 needs to be consistent. If the laser 21 emits red, green and blue lasers, since the red laser is P light and the green and blue lasers are S light under normal circumstances, in order to make the polarization directions of the red, green and blue lasers consistent, the light beam emitted by the laser 21 can be modulated by a wave plate or other device that can change the polarization direction of the light beam. Under normal circumstances, the light beam emitted by the laser 21 can be modulated into S light. In the present application, it can be considered that the light beam emitted by the laser 21 is a light beam with a consistent polarization direction after modulation, which can be S light or P light.

[0049] Taking the light beam emitted by the laser 21 as S light for example, the light beam emitted by the laser 21 is converged to the light pipe 23 by the converging reflector 22, and the S light is obtained after being homogenized by the light pipe 23, the illumination lens group 24 and the polarizer 25. Since the PBS 26 can transmit the P light and reflect the S light, the light beam is reflected to the LCOS 27 via the PBS 26. Since the LCOS 27 can change the polarization direction of the incident polarized light, the light beam can be converted from the S light to the P light after being reflected by the LCOS 27, and is emitted to the projection lens 28 via the PBS 26 to be projected onto the screen.

[0050] After the light beam is emitted from the laser 21, it will generate reflected light after passing through the surfaces of various optical devices. The reflected light will be reflected multiple times by the surfaces of structural parts and optical devices, forming a stray light environment inside the laser projection device. If not controlled, the stray light will be incident on the projection lens 28, and then projected onto the screen through the projection lens 28, thereby reducing the contrast of the picture.

[0051] Figure 3 A schematic diagram of a projection lens structure in the related art, referring to Figure 3 As shown, the projection lens 28 includes multiple lenses. The light reflected by the LCOS 27 can be incident on the lens in the projection lens 28 after passing through the PBS 26. After the light beam enters the projection lens 28, it is reflected multiple times by the surfaces of multiple lenses in the projection lens 28 and the surface of the lens barrel, which will also form stray light and reduce the contrast of the picture.

[0052] in, Figure 3 The dashed line shown is used to schematically represent the transmission process of the light beam in the projection lens, and is only used to illustrate the overall transmission direction of the light beam, and does not limit the specific transmission angle of the light beam in the projection lens.

[0053] From the above, we can see that in laser projection equipment, stray light is generally generated based on the following two factors:

[0054] 1. In the optical path from the laser to the LCOS, there is a certain degree of reflection on the surfaces of the optical devices and the shell of the laser projection equipment. The light is reflected multiple times between the surfaces, forming a background of stray light at the entrance of the projection lens. Some of the stray light will be projected onto the screen through the lens.

[0055] 2. There is light reflection from the PBS to the surface of each lens in the projection lens. The reflected light reflects back and forth on the lenses inside the projection lens, forming stray light, and some of the stray light will be projected onto the screen through the lens.

[0056] Based on this, in order to improve the contrast of the picture, it is necessary to reduce stray light. In the related art, the intensity of reflected light can be reduced by increasing the surface transmittance of the lens, and at the same time, light-absorbing paint or matte threads can be applied to the surface of the lens barrel to reduce stray light. However, since the degree of improvement of the surface transmittance of the lens is limited, and light-absorbing paint and matte threads can only reduce part of the stray light, there is still some stray light projected onto the screen through the projection lens, resulting in a low contrast of the picture.

[0057] The present application provides a projection lens and a laser projection device. As can be seen from the above, in the optical path from the laser to the LCOS, the LCOS will change the polarization direction of the incident light beam, so the polarization direction of the first stray light in the optical path from the laser to the LCOS is different from the polarization direction of the imaging light beam reflected by the LCOS to the projection lens, so a polarization reflection device can be set inside the projection lens, based on the polarization direction, the imaging light beam is transmitted so that the imaging light beam enters the subsequent optical path, and the first stray light is reflected to eliminate the light path, or the imaging light beam is reflected so that the imaging light beam enters the subsequent optical path, and the first stray light is transmitted to eliminate the light path. At this time, the first stray light generated in the optical path from the laser to the LCOS, that is, the light that is not modulated by the LCOS, can be eliminated, effectively avoiding the first stray light from being projected onto the screen through the projection lens, thereby improving the picture contrast.

[0058] Since the second stray light generated inside the projection lens is consistent with the polarization direction of the imaging light beam, the second stray light generated inside the projection lens cannot be eliminated based on the polarization direction. In order to further eliminate the second stray light generated inside the projection lens, an angle selection film layer may be coated on the polarization reflector. The angle selection film layer can transmit light within a specific angle range and reflect light at other angles, or reflect light within a specific angle range and transmit light at other angles. At the same time, since the imaging light beam has a certain angle range when it is incident on the polarization reflector, the imaging light beam can be transmitted or reflected to the subsequent light path based on the angle selection film layer, and the second stray light outside the angle range can be eliminated from the light path, effectively reducing the second stray light, and avoiding the second stray light generated inside the projection lens from being projected onto the screen through the projection lens, further improving the picture contrast.

[0059] Figure 4 A schematic diagram of a projection lens structure provided in an embodiment of the present application Figure 1 ,refer to Figure 4 As shown, the projection lens 40 includes:

[0060] A polarized reflection device 401, configured to transmit the imaging light beam and reflect the first stray light based on the polarization direction of the imaging light beam, or to reflect the imaging light beam and transmit the first stray light;

[0061] The polarized reflective device 401 is coated with an angle selection film layer, and the angle selection film layer is used to transmit the imaging light beam and reflect the second stray light based on the angle range of the imaging light beam incident on the polarized reflective device 401, or reflect the imaging light beam and transmit the second stray light;

[0062] The imaging light beam is a light beam incident on the projection lens 40 after being modulated by the light valve modulation device, the first stray light is a light beam incident on the projection lens 40 without being modulated by the light valve modulation device, and the polarization direction of the first stray light is different from the polarization direction of the imaging light beam;

[0063] The second stray light is stray light generated inside the projection lens 40 .

[0064] In some embodiments, the polarized reflective device may be Figure 4 The polarizing reflector shown may also be in the form of other light-reflecting devices, such as prisms, etc., and the surface of the prisms also needs to be coated with a corresponding angle-selective film.

[0065] Figure 4 In addition to the polarized reflector 401, multiple lenses included in the projection lens 40 are also shown. Since the multiple lenses included in the projection lens 40 are not the focus of this application, please refer to the relevant public information or documents, and this application will not explain them again.

[0066] The imaging beam is a beam that is modulated by the light valve modulation device and then incident on the projection lens 40, and can also be called an effective beam, which is used for imaging. In the optical path between the laser and the light valve modulation device, the stray light generated by reflection is not modulated by the light valve modulation device, and the beam incident on the projection lens 40 is called the first stray light.

[0067] Since the light valve modulation device can be LCOS, LCD or DMD, etc., for LCOS and LCD, they can change the polarization direction of the incident light beam, so that the polarization direction of the imaging light beam and the first stray light are different. For DMD, since DMD cannot change the polarization direction of the incident light beam, a polarization conversion device can be set between DMD and the prism assembly to be equivalent to LCOS, so that the polarization directions of the first stray light and the imaging light beam are different. The specific principle can be referred to the following embodiments, which will be described in detail.

[0068] After the LCOS modulated light beam, ie, the imaging light beam, enters the projection lens 40 , some stray light, ie, the second stray light, is also generated inside the projection lens 40 .

[0069] Based on the polarization direction and angle range, the polarization reflective device 401 transmits or reflects the imaging light beam, which depends on the design of the subsequent optical path. The transmission and reflection functions of the polarization reflective device 401 can be changed according to actual usage requirements.

[0070] In one implementation scenario, based on Figure 4 If the projection lens 40 includes multiple lenses Figure 4The structure shown in the figure is arranged. At this time, if it is necessary to inject the imaging beam into the subsequent optical path, the first stray light and the second stray light are removed from the optical path. Therefore, the polarized reflection device 401 can transmit the imaging beam and reflect the first stray light and the second stray light. Figure 4 E L Used to represent the imaging beam, S L Used to represent the first stray light and the second stray light.

[0071] based on Figure 4 The structure of the projection lens 40 shown is illustrated by taking the light beam emitted by the laser as S light and the light valve modulation device as LCOS as an example. Before the light beam is incident on the LCOS, that is, in the light path between the laser and the LCOS, the light beam is S light. The light beam is incident on the LCOS and is converted into P light after being reflected by the LCOS. Therefore, the imaging light beam is P light, and the first stray light is S light. The imaging light beam and part of the first stray light are incident on the projection lens 40, and further incident on the polarization reflection device 401. The polarization reflection device 401 can transmit the P light to transmit the imaging light beam to the subsequent light path, and reflect the S light to reflect the first stray light, that is, the light whose polarization direction is not modulated by the LCOS, out of the light path.

[0072] In another implementation scenario, based on Figure 4 In the structure of the projection lens 40 shown, if the light beam emitted by the laser is P light, and the light valve modulation device is still LCOS, the light beam is converted into S light after being reflected by LCOS, so the imaging light beam is S light, and the first stray light is P light. Therefore, the polarized reflection device 401 can transmit S light to transmit the imaging light beam to the subsequent light path, and reflect P light to eliminate the first stray light.

[0073] Figure 5 A schematic diagram of a projection lens structure provided in an embodiment of the present application Figure 2 At this time, if the imaging beam needs to be incident on the subsequent optical path and the first stray light and the second stray light need to be removed from the optical path, the polarized reflection element 401 needs to reflect the imaging beam and transmit the first stray light and the second stray light.

[0074] In one implementation scenario, based on Figure 5 The structure of the projection lens 40 shown is illustrated by taking the light beam emitted by the laser as S light and the light valve modulation device as LCOS as an example. At this time, the light beam is converted into P light after being reflected by LCOS, that is, the imaging light beam is P light, and the first stray light in the light path between the laser and LCOS is S light. Therefore, the polarized reflection device 401 needs to reflect the P light to reflect the imaging light beam into the subsequent light path, and transmit the S light to eliminate the first stray light to prevent the first stray light from entering the subsequent light path.

[0075] Because the reflection efficiency of S light is usually higher, in order to improve the system efficiency, the P light obtained after the LCOS reflection can be tuned into S light, and then incident on the polarization reflection device 401.

[0076] Still refer to Figure 5 As shown, in some embodiments, if the polarization reflection device 401 is used to reflect the imaging light beam and transmit the first stray light based on the polarization direction of the imaging light beam, the projection lens 40 further includes: a first polarization conversion device 402;

[0077] The first polarization conversion device 402 is used to change the polarization direction of the imaging light beam, so that the polarization reflection device 401 reflects the imaging light beam with the polarization direction changed.

[0078] The first polarization conversion device 402 may be a wave plate or other device capable of converting polarization direction. When the first polarization conversion device 402 is a wave plate, it may be a 1 / 2 wave plate because the first polarization conversion device 402 needs to realize the conversion of P light and S light.

[0079] The first polarization conversion device 402 may be located inside the projection lens 40 or outside the projection lens 40. Figure 5 The prism assembly 50 and the light valve modulation device 60 are embodied in FIG.

[0080] When the first polarization conversion device 402 is located inside the projection lens 40, it is only necessary that the imaging light beam is incident on the first polarization conversion device 402 first and then incident on the polarization reflection device 401. The specific position of the first polarization conversion device 402 is not limited. Figure 5 Only one position of the first polarization conversion device 402 inside the projection lens 40 is shown. At this time, the imaging light beam is converted from P light to S light after passing through the first polarization conversion device 402, and the first stray light is converted from S light to P light after passing through the first polarization conversion device 402. Therefore, the imaging light beam incident on the polarization reflection device 401 is S light, and the first stray light incident on the polarization reflection device 401 is P light. At this time, the polarization reflection device 401 can reflect the S light to reflect the imaging light beam into the subsequent optical path, and transmit the P light to transmit the first stray light out of the optical path.

[0081] When the first polarization conversion device 402 is located outside the projection lens 40, it can be located at the entrance of the projection lens 40. For details, please refer to Figure 6 As shown, Figure 6 A schematic diagram of a projection lens structure provided in an embodiment of the present application Figure 3Specifically, when the light valve modulation device 60 is an LCOS or DMD, the first polarization conversion device 402 is located between the projection lens 40 and the prism assembly 50. When the light valve modulation device 60 is an LCD, the first polarization conversion device 402 is located between the projection lens 40 and the LCD.

[0082] In another implementation scenario, based on Figure 5 In the structure of the projection lens 40 shown, if the light beam emitted by the laser is P light, and the light valve modulation device 60 is LCOS, the light beam is converted into S light after being reflected by the LCOS, that is, the imaging light beam is S light. At this time, the first stray light is P light, so the polarized reflection device 401 can reflect the S light to reflect the imaging light beam into the subsequent light path, and transmit the P light to remove the first stray light from the light path.

[0083] It should be noted that, since the imaging light beam is S light at this time, the polarization reflection device 401 can reflect the imaging light beam to the subsequent optical path by reflecting the S light, so there is no need to set the first polarization conversion device 402 at this time.

[0084] In some embodiments, the light valve modulation device 60 in the laser projection device can also be an LCD. For LCD, since LCD also changes the polarization direction of the incident light beam, the principle of removing the first stray light and the second stray light based on the polarization reflection device 401 is basically the same as that of LCOS, and will not be described in detail here. However, since LCOS is a reflective system and LCD is a transmissive system, the light beam will be transmitted to the projection lens 40 after being modulated by the LCD, so there will be a certain difference in the relative position of the light valve modulation device 60 and the projection lens 40.

[0085] As can be seen from the above, since the polarization direction of the first stray light in the optical path between the laser and the light valve modulation device 60 is different from that of the imaging light beam, the polarization reflection device 401, based on the polarization direction, injects the imaging light beam into the subsequent optical path to achieve projection, and removes the first stray light from the optical path to avoid the first stray light being projected onto the screen through the projection lens 40, which is beneficial to improving the picture contrast.

[0086] As for the second stray light inside the projection lens 40, since there is a certain angle range when the imaging light beam is incident on the polarized reflective device 401, and the second stray light has no corresponding angle range or has a larger angle range, an angle selection film layer can be plated on the surface of the polarized reflective device 401. Based on the angle selection characteristics of the angle selection film layer, the second stray light inside the projection lens 40 is removed from the light path.

[0087] In some embodiments, the angle range of the imaging light beam incident on the polarized reflective device 401 is the sum of the divergence angle corresponding to the imaging light beam incident on the polarized reflective device 401 and the tilt angle of the polarized reflective device 401, and the tilt angle is the angle between the polarized reflective device 401 and the optical axis of the projection lens 40.

[0088] The polarized reflective device 401 is placed at a certain tilt angle in the optical path inside the projection lens 40, and can be located at different positions inside the projection lens 40. The present application does not limit its placement position. However, it should be noted that when the placement position of the polarized reflective device 401 is different, the divergence angle corresponding to the imaging light beam incident on the polarized reflective device 401 will also be different, which will lead to different angle ranges of the imaging light beam incident on the polarized reflective device 401. Accordingly, the angle selection film layer coated on the surface of the polarized reflective device 401 also needs to change accordingly.

[0089] In one implementation scenario, the polarized reflector 401 can be placed at the aperture position inside the projection lens 40. Figure 4 At the position of the polarized reflector 401 shown, if the divergence angle of the imaging light beam incident on the polarized reflector 401 is ±α, and the inclination angle of the polarized reflector 401 is θ, then the angle range of the imaging light beam incident on the polarized reflector 401 is θ±α.

[0090] If based on Figure 4 In the structure of the projection lens 40 shown, the angle selection film layer coated with the polarized reflector 401 can transmit the light beam with an angle within θ±α and reflect the light beam with an angle beyond the θ±α range. The light beam with an angle within θ±α is the imaging light beam, and the light beam beyond the θ±α range is the second stray light. Thus, at the polarized reflector 401, the imaging light beam is transmitted to the subsequent optical path, and the second stray light beyond the projection field angle in the optical path inside the projection lens 40 is removed from the optical path.

[0091] If based on Figure 5 In the structure of the projection lens 40 shown, if the divergence angle of the imaging light beam incident on the polarized reflector 401 is ±β, the tilt angle of the polarized reflector 401 is still recorded as θ, and for the angle selection film layer coated with the polarized reflector 401, the light beam with an angle within θ±β needs to be reflected, and the light beam beyond the angle range of θ±β needs to be transmitted. Among them, the light beam with an angle within θ±β is the imaging light beam, and the light beam beyond the angle range of θ±β is the second stray light, so that the imaging light beam is reflected to the subsequent light path, and most of the second stray light generated inside the projection lens 40 is removed from the light path.

[0092] In some embodiments, the angle between the polarized reflector 401 and the optical axis of the projection lens 40 is 45°, and the polarized reflector 401 is tilted at 45° to achieve a better effect of transmitting P light and reflecting S light, or transmitting S light and reflecting P light.

[0093] In addition to 45°, the angle between the polarized emission device and the optical axis of the projection lens 40 may also be other angles, which is not limited in the present application.

[0094] In some embodiments, the projection lens 40 further includes: a housing, and a region of the housing that receives the first stray light and the second stray light is a lens barrel structure or is coated with a light absorbing material.

[0095] In one implementation scenario, the lens barrel structure may be a matte thread or other matte structure, which further reduces the first stray light and the second stray light and improves the image contrast through the combination of optics and structure.

[0096] The embodiment of the present application provides a projection lens 40, which includes a polarized reflective device 401. The polarized reflective device 401 can transmit the imaging beam and reflect the first stray light based on the polarization direction of the imaging beam, or reflect the imaging beam and transmit the first stray light, so that the imaging beam is incident on the subsequent optical path and the first stray light is removed from the optical path. At the same time, the polarized reflective device 401 is also coated with an angle selection film layer, which can transmit the imaging beam and reflect the second stray light based on the angle range of the imaging beam incident on the polarized reflective device 401, or reflect the imaging beam and transmit the second stray light, so that the second stray light can be removed from the optical path, and the imaging beam is incident on the subsequent optical path, and is projected onto the screen through the projection lens 40 to form an image. Based on the generation principle of stray light, the polarized reflection device 401 in the projection lens 40 of the present application can not only eliminate the first stray light that is not modulated by the light valve modulation device 60 and is incident on the projection lens 40, but can also eliminate the second stray light generated inside the projection lens 40 and exceeding the projection field of view, thereby effectively reducing the stray light, improving the contrast of the displayed image, and improving the image display quality.

[0097] Figure 7 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 2 ,refer to Figure 7 As shown, the laser projection device includes a laser 70, an illumination light path 80, a prism assembly 50, a light valve modulation device 60 and a projection lens 40 as described in any one of the above items.

[0098] The structure of the projection lens 40 of the present application and the principle of eliminating the first stray light and the second stray light can be referred to the above embodiments, and the present application will not elaborate on them in detail.

[0099] In some embodiments, the light valve modulation device 60 is a digital micromirror device, a liquid crystal on silicon, or a liquid crystal display.

[0100] In one implementation scenario, when the light valve modulation device 60 is a digital micromirror device, the prism assembly 50 may be a total reflection prism. If the light valve modulation device 60 is a silicon-based liquid crystal or a liquid crystal display, the prism assembly 50 may be a polarization beam splitter prism.

[0101] Figure 8 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 3 ,refer to Figure 8 As shown, in one implementation scenario, if the light valve modulation device 60 is a digital micromirror device, the laser projection device further includes a second polarization conversion device 90, which is located between the prism assembly 50 and the light valve modulation device 60, and is used to change the polarization direction of the imaging light beam.

[0102] The second polarization conversion device 90 may be a wave plate or other device capable of changing the polarization direction of a light beam.

[0103] based on Figure 8 As shown, at this time, the light valve modulation device 60 is a digital micromirror device. Since the second polarization conversion device 90 is located between the prism assembly 50 and the digital micromirror device, the light beam will pass through the second polarization conversion device 90 once when the prism assembly 50 reflects the light beam to the digital micromirror device. After the digital micromirror device modulates the light beam, it reflects the light beam to the prism assembly 50, so that it is incident on the projection lens 40 through the prism assembly 50. At this time, when the digital micromirror device reflects the light beam to the prism assembly 50, the light beam will pass through the second polarization conversion device 90 again. Therefore, the light beam passes through the prism assembly 50-second polarization conversion device 90-digital micromirror device-second polarization conversion device 90-prism assembly 50, and is incident on the projection lens 40. The light beam passes through the second polarization conversion device 90 twice in total.

[0104] If the light beam emitted by the laser 70 is S light, the imaging light beam incident to the projection lens 40 needs to be P light, and the second polarization conversion device 90 can be a quarter wave plate. Similarly, if the light beam emitted by the laser 70 is P light, the imaging light beam incident to the projection lens 40 needs to be S light, and the second polarization conversion device 90 can also be a quarter wave plate.

[0105] For liquid crystal on silicon or liquid crystal displays, since they can change the polarization direction of the light beam so that the polarization directions of the first stray light and the imaging light beam are different, there is no need to set up a second polarization conversion device.

[0106] Still refer to Figure 8 As shown, in some embodiments, the illumination light path 80 includes a homogenization device 802, an illumination lens group 803, and a polarizer 804;

[0107] The homogenizing device 802 is used to homogenize the laser light emitted by the laser 70;

[0108] The illumination mirror group 803 is located at the light output side of the homogenization device 802 and is used to shape the laser;

[0109] The polarizer 804 is located between the lighting lens assembly 803 and the prism assembly 50 , and is used to transmit light in a target polarization direction and filter out light in other polarization directions except the target polarization direction.

[0110] The homogenizing device 802 may be a light pipe or a fly-eye lens, etc. In one implementation scenario, if the homogenizing device 802 is a light pipe, the illumination optical path 80 further includes a converging reflector 801 located at the light output side of the laser 70, for reflecting the laser light emitted by the laser 70 and converging it to the light pipe.

[0111] In one implementation scenario, the converging reflector 801 may be a converging reflector, such as Figure 8 In addition to the converging reflector, the converging reflector 801 can also be one or more devices capable of reflecting and converging the laser light emitted by the laser 70, for example, it can be a combination of a reflector and a converging lens to converge the laser light to the light guide. For details, please refer to Fig. 9 As shown, Fig. 9 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 4 , wherein the converging reflective device 801 includes a reflector 8011 and a converging lens 8012 .

[0112] In another implementation scenario, if the homogenization device 802 is a fly-eye lens, please refer to Fig.10 As shown, Fig.10 A schematic diagram of a laser projection device provided in an embodiment of the present application Figure 5 , wherein the illumination optical path 80 may include a light combining component 805 and a first lens group 806, the light combining component 805 is located on the light emitting side of the laser 70, the first lens group 806 is located between the light combining component 805 and the fly-eye lens, and the light combining component 805 combines the laser light emitted by the laser 70 and then emits it to the fly-eye lens through the first lens group 806.

[0113] The light in the target polarization direction may be S light or P light, which may be set according to actual needs. The polarizer 804 filters out the light in other polarization directions except the target polarization direction to increase the linear polarization degree.

[0114] It should be noted that the structures of the various laser projection devices shown in this application are only exemplary, and this application does not limit the structures of the laser projection devices.

[0115] An embodiment of the present application provides a laser projection device, which includes a laser 70, an illumination optical path 80, a prism assembly 50, a light valve modulator 60, and a projection lens 40 provided in the above embodiment. The projection lens 40 can eliminate the first stray light generated in the optical path between the laser 70 and the light valve modulator 60 and the second stray light generated inside the projection lens 40, thereby avoiding the first stray light and the second stray light from being projected onto the screen through the projection lens 40, effectively improving the picture contrast and improving the picture display effect.

[0116] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0117] For the convenience of explanation, the above description has been made in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or limit the embodiments to the specific forms disclosed above. Based on the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different variations of the embodiments suitable for specific use considerations.

Claims

1. A projection lens, characterized in that: The projection lens comprises: a polarization reflection device, configured to transmit the imaging light beam and reflect the first stray light based on the polarization direction of the imaging light beam, or to reflect the imaging light beam and transmit the first stray light; The polarized reflective device is coated with an angle selection film layer, and the angle selection film layer is used to transmit the imaging light beam and reflect the second stray light based on the angle range of the imaging light beam incident on the polarized reflective device, or reflect the imaging light beam and transmit the second stray light; The imaging light beam is a light beam incident on the projection lens after being modulated by a light valve modulation device, the first stray light is a light beam incident on the projection lens without being modulated by the light valve modulation device, and the polarization direction of the first stray light is different from the polarization direction of the imaging light beam; The second stray light is stray light generated inside the projection lens.

2. The projection lens according to claim 1, characterized in that: The angle range of the imaging light beam incident on the polarized reflective device is the sum of the divergence angle corresponding to the imaging light beam incident on the polarized reflective device and the tilt angle of the polarized reflective device, and the tilt angle is the angle between the polarized reflective device and the optical axis of the projection lens.

3. The projection lens according to claim 2, characterized in that: The angle between the polarized reflective element and the optical axis of the projection lens is 45°.

4. The projection lens according to claim 1, characterized in that: If the polarization reflection device is used to reflect the imaging light beam and transmit the first stray light based on the polarization direction of the imaging light beam, the projection lens further includes: a first polarization conversion device; The first polarization conversion device is used to change the polarization direction of the imaging light beam, so that the polarization reflection device reflects the imaging light beam with the polarization direction changed.

5. The projection lens according to claim 1, wherein: The projection lens further includes: a housing, wherein a region of the housing that receives the first stray light and the second stray light is a lens barrel structure or is coated with a light absorbing material.

6. A laser projection device, characterized in that: The laser projection device comprises a laser, an illumination light path, a prism assembly, a light valve modulation device and the projection lens according to any one of claims 1 to 5.

7. The laser projection device according to claim 6, characterized in that: The light valve modulation device is a digital micromirror device, a silicon-based liquid crystal or a liquid crystal display.

8. The laser projection device according to claim 7, characterized in that: If the light valve modulation device is a digital micromirror device, the laser projection device further comprises a second polarization conversion device, which is located between the prism assembly and the light valve modulation device and is used to change the polarization direction of the imaging light beam.

9. The laser projection device according to claim 6, characterized in that: The illumination light path includes a homogenizing device, an illumination lens group and a polarizer; The homogenizing device is used to homogenize the laser light emitted by the laser; The illumination mirror group is located at the light output side of the homogenizing device and is used to shape the laser; The polarizer is located between the lighting lens assembly and the prism assembly, and is used to transmit light in a target polarization direction and filter out light in other polarization directions except the target polarization direction.

10. The laser projection device according to claim 9, characterized in that: If the homogenizing device is a light guide tube, the illumination optical path further comprises a converging reflective device, which is located at the light output side of the laser and is used to reflect the laser light emitted by the laser and converge it onto the light guide tube.

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