Laser light source

Abstract

The application provides a laser light source, which has a first light emitting area, a second light emitting area and a third light emitting area on a light emitting surface of a laser assembly, and emits three color laser beams into a receiving cavity of a light source shell respectively, wherein the divergence angle of the third color laser beam is greater than the divergence angle of the first color laser beam and the second color laser beam, and the spot area of the first color laser beam and the second color laser beam is smaller than the spot area of the third color laser beam; a light emitting surface of the laser assembly is provided with a light combining lens group in the receiving cavity; the light combining lens group comprises three light combining lens pieces arranged on the light emitting path of the light emitting area emitting the corresponding color laser beam; wherein at least one light combining lens piece transmits the light beams of other light emitting areas corresponding to the color, and combines the reflected light beams, and emits along the light emitting direction of the laser light source. The laser light source provided by the application improves the display quality of the projection picture.

Description

[0001] This application is a divisional application based on Chinese invention application 202010247120.7 (2020-3-31), invention name: Laser projection equipment. Technical Field

[0002] The present application relates to the field of laser projection display technology, and in particular to a laser projection device. Background Art

[0003] Laser light sources offer advantages such as good monochromaticity, high brightness, and long life, making them ideal light sources. As laser device power increases to meet the requirements of industrial applications, lasers are increasingly being used as lighting sources. For example, in recent years, lasers have been used as projection light sources in projection equipment, gradually replacing mercury lamps. Compared to LED light sources, lasers also offer the advantages of low etendue and high brightness.

[0004] Lasers are categorized by their emission type: blue lasers, red lasers, and green lasers, emitting blue, red, and green lasers, respectively. Blue lasers were the first to be industrialized. Red and green lasers were previously unusable due to limitations in their power output (e.g., emitting power less than 1W and low brightness). Consequently, most laser projection light sources in the industry are hybrid laser sources combining monochromatic lasers (blue lasers) and fluorescent light, with the fluorescent light being excited by the blue laser.

[0005] Solid-state lasers are essentially a PN junction semiconductor, such as Figure 1 The schematic diagram of the laser light-emitting chip shown in the figure. The active layer is located between the P-type semiconductor and the N-type semiconductor. The oscillation of the resonant cavity in the active region causes lasers of different wavelengths to be emitted from the front cavity surface. Specifically, the laser beam is as follows: Figure 2-1 As shown, a radial beam is emitted from the light-emitting point. The α and β in the figure refer to the divergence angles of the slow axis and the fast axis respectively. It can be seen from the figure that the fast axis diverges faster and the angle is larger, while the slow axis diverges relatively slowly and the angle is smaller, so the shape of the laser beam is elliptical.

[0006] Among them, blue laser and green laser can be generated by gallium arsenide luminescent materials, and red laser is generated by gallium nitride luminescent materials. Due to the different luminescence mechanisms of luminescent materials, in the process of generating different colored lasers, the luminescence efficiency of red laser is lower and the thermal conversion rate is higher. The luminescence efficiency of blue laser and green laser is relatively high, and the luminescence requirements can be met by setting a luminescence point on the corresponding chip. In order to meet the requirements of luminous power, such as Figure 2-2As shown, multiple light-emitting points need to be set on the red laser chip to increase the light-emitting power, which also makes the size of the red laser beam relatively large. At the same time, due to the different light-emitting mechanisms of the light-emitting materials, the divergence speed of the fast and slow axes of the red laser is greater than that of the blue and green lasers.

[0007] However, the differences between the red laser and the blue and green lasers mentioned above result in some problems with the quality and efficiency of the three-color light combination when the three-color laser is used as a light source. In laser projection equipment, this will cause a decrease in the quality of the projected image. Summary of the Invention

[0008] The present application provides a laser projection device that can solve the problem.

[0009] To achieve the above technical objectives, the present application provides a laser projection device, comprising a light source for providing an illumination beam; an optical engine for modulating the illumination beam; and a lens for receiving the modulated illumination beam for projecting an image.

[0010] The light source includes:

[0011] A laser assembly having a first light emitting area, a second light emitting area, and a third light emitting area, emitting a first color laser beam, a second color laser beam, and a third color laser beam, respectively, wherein the parallelism of the first color laser beam and the second color laser beam is less than the parallelism of the third color laser beam;

[0012] A light combining lens assembly is used to make a 90-degree turn of the laser beam emitted from the light emitting area and then emit it toward the light outlet of the light source;

[0013] Among them, the light-combining lens group includes at least a third light-combining lens, the first color laser beam and the second color laser beam are incident on the first surface of the third light-combining lens and transmit through; the first surface has a raised microstructure; the third color laser beam is incident on the second surface of the third light-combining lens and is reflected toward the light outlet of the light source.

[0014] In the technical solution of the laser projection device provided in the present application, a laser component that emits different colors is used as a projection light source, and different light-emitting areas of the laser component emit laser beams of different colors. The parallelism of the first color laser beam and the second color laser beam are both smaller than the parallelism of the third color laser beam, that is, the beam divergence angle of the third color laser beam is greater than the beam angle of the first color laser beam and the second color laser beam. When the first color laser beam and the second color laser beam are incident on the third light-combining lens and transmitted through the third light-combining lens, the third color laser beam is also incident on the third light-combining lens but is reflected. In this way, the three-color laser light is combined through the third light-combining lens, and the first surface of the third light-combining lens on which the first color laser beam and the second color laser beam are incident has a raised microstructure. These raised microstructures can increase the divergence angle of the first color laser beam and the second color laser beam, so that the beam angles of the first color laser beam and the second color laser beam and the third color laser beam are close to or consistent with each other. In this way, after the laser beams of different colors are combined, the overlap of the light spots is improved, thereby improving the color uniformity of the combined light spots and improving the display quality of the projection image. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0016] Figure 1 This is a schematic diagram of the principle of a laser light-emitting chip;

[0017] Figure 2-1 This is a schematic diagram of the principle of the laser light-emitting chip emitting a light beam;

[0018] Figure 2-2 This is a schematic diagram of the principle structure of a red laser light-emitting chip;

[0019] Figure 3 A schematic structural diagram of a laser projection device provided in an embodiment of the present application;

[0020] Figure 4-1 A schematic diagram of an optical engine structure provided in an embodiment of the present application;

[0021] Figure 4-2 A schematic diagram of the decomposition structure of an optical engine provided for the implementation of this application;

[0022] Figure 5 Schematic diagram of the optical principle of the laser projection device provided in an embodiment of the present application;

[0023] Figure 6-1 A schematic diagram of a light source structure provided in an embodiment of the present application;

[0024] Figure 6-2 for Figure 6-1 A schematic cross-sectional view of a light source structure;

[0025] Figure 7-1 A schematic diagram of the internal structure of a light source provided in an embodiment of the present application;

[0026] Figure 7-2 A schematic diagram of the internal structure of another light source provided in an embodiment of the present application;

[0027] Figure 7-3 A schematic diagram of the internal structure of another light source provided in an embodiment of the present application;

[0028] Figure 7-4 A schematic diagram of the internal structure of another light source provided in an embodiment of the present application;

[0029] Figure 7-5 A schematic diagram of the internal structure of another light source provided in an embodiment of the present application;

[0030] Figure 7-6 A schematic diagram of the internal structure of another light source provided in an embodiment of the present application;

[0031] Figure 8-1 6 is a schematic diagram of the laser structure;

[0032] Figure 8-2 6 is a schematic diagram of the laser assembly structure;

[0033] Figure 9-1 Schematic diagram of a light source structure;

[0034] Figure 9-2 for Figure 9-1 Spot distribution diagram of the illumination beam output by the central light source;

[0035] Figure 10 Schematic diagram of laser polarization polarity;

[0036] Figure 11 This is a structural schematic diagram of the third light-combining lens in the light source embodiment of the present application. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] Figure 3 A schematic diagram of the structure of a laser projection device is shown. Figure 3 The laser projection device example shown is used to illustrate the structure and working process of the laser projection device of this embodiment.

[0039] The laser projection device 10 comprises a housing 011 and a base 012. The housing 011 and base 012 form a housing space within which are located a light source 100, an optical engine 200, and a lens 300, mounted on the base 012. These three components constitute the optical engine and are sequentially connected along the beam propagation direction. Each of these components is enclosed in a corresponding housing to support the optical components and ensure they meet certain sealing or airtight requirements.

[0040] A plurality of circuit boards 400 are also included in the accommodation space formed by the entire housing 011 and the base 012 . The plurality of circuit boards 400 are parallel to each other and are located inside the entire housing 011 and vertically disposed on the base 012 .

[0041] In one specific implementation, see Figure 3 The optical engine 200 and lens 300 are connected and arranged along a first direction of the entire device. For example, the first direction can be the width of the entire device, or depending on the usage, the first direction is opposite to the user's viewing direction. The connection direction of the light source 100 and the optical engine 200 is perpendicular to the first direction. As a result, the optical engine composed of the light source 100, optical engine 200, and lens 300 is connected in an "L" shape. The optical engine is located at the corner of the "L". As a result, the optical axis makes a 90-degree turn, which shortens the length of the optical path in one direction.

[0042] See also Figure 3 The laser projection device 10 also includes multiple circuit boards 400, which are arranged vertically relative to the base 102 and along the inner side of the overall housing 011. The illustration only schematically illustrates a portion of the overall housing 101. Specifically, the multiple circuit boards 400 are arranged parallel to each other and close to the inner side of the overall housing 101. The overall housing 101 is typically a housing including a top cover. The housing described herein may refer to the outer shell surrounding the device body.

[0043] The multiple circuit boards 400 include a power supply board, also known as a power board, which is used to provide power for multiple modules of the device; a display board, which is mainly used to control the imaging of the projection system, which is a DLP system in this embodiment, such as the generation of DMD chip signals, the output of light source timing signals and PWM brightness dimming signals, etc.; a signal transmission board, also known as a TV board, which is mainly used to decode the video signal to form an image signal and transmit it to the display board for further image processing.

[0044] Figure 5 The optical path principle diagram of the above laser projection device is given as an example. Figure 5 As shown, the light beam output by the light source 100 is incident on the optical engine 200, and the optical engine 200 then transmits the light beam to the lens 300. In one specific implementation, the light source 100 is a three-color laser light source that can output red, green and blue lasers. The light source 100 also includes a plurality of optical lenses to combine and converge the laser beams. Since the laser itself has strong coherence, in order to improve the speckle problem caused by laser projection, a speckle elimination component may be provided in the optical path from the light source 100 to the optical engine 200, such as a moving diffuser. After the light beam is diffused by the moving diffuser, the divergence angle of the light beam can be increased, which is conducive to improving the speckle phenomenon. The moving diffuser can be provided in the light source 100 or in the optical engine 200.

[0045] The light beam emitted from light source 100 enters optical engine 200. A homogenizing component, such as a light pipe, is typically located at the front end of optical engine 200. This component receives the light beam from the light source and mixes and homogenizes the light. The rectangular exit of the light pipe shapes the light spot. Optical engine 200 also includes multiple lens elements. TIR or RTIR prisms form the illumination light path, directing the light beam to a key component—a light valve. The light valve modulates the light beam, which then enters the lens assembly of lens 300 for imaging.

[0046] Depending on the projection architecture, light valves can include various types, such as LCOS, LCD, or DMD. In this example, a DLP (Digital Light Processing) projection architecture is used, and the light valve is a DMD chip, also known as a digital micromirror array. Before the light beam from light source 100 reaches the DMD light valve, it undergoes optical mechanical shaping to meet the illumination size and incident angle required by the DMD. The DMD surface comprises thousands of tiny mirrors, each of which can be individually driven for deflection. For example, the DMD chip provided by TI can achieve a deflection range of ±12 degrees or ±17 degrees. Light reflected at a positive deflection angle is called ON light, while light reflected at a negative deflection angle is called OFF light. OFF light is ineffective light and is typically reflected by the housing or absorbed by a light-absorbing device. ON light is the effective light beam that is received by the tiny mirrors on the DMD light valve surface and incident on the lens unit 300 at a positive deflection angle for projection imaging. The quality of the illumination light beam emitted by the light source 100 directly affects the quality of the light beam irradiated on the surface of the light valve DMD, and thus the light beam is projected by the lens 300 and reflected on the projection screen.

[0047] In this example, lens 300 is an ultra-short-throw projection lens. The light beam modulated by the light valve enters the lens and is finally emitted obliquely upward. This is different from the light emission method of traditional long-throw projection in which the optical axis of the projection beam is located on the vertical line of the projection screen. The ultra-short-throw projection lens usually has an offset of 120% to 150% relative to the projection screen. This projection method has a smaller throw ratio (which can be understood as the ratio of the distance between the projection host and the projection screen to the diagonal size of the projection screen), such as about 0.2 or even smaller, which can make the projection device closer to the projection screen, making it suitable for home use. However, this light emission method also determines that the light beam has higher uniformity. Otherwise, compared with traditional long-throw projection, the brightness or color unevenness of the projection screen will be more obvious.

[0048] In this example, when using a single DMD light valve component, light source 100 can sequentially output the three primary colors. Based on the principle of three-color light mixing, the human eye cannot distinguish the color of light at any given moment and still perceives a mixed white light. However, when using multiple light valve components, such as three DMDs or a three-chip LCD light valve, the three primary colors in light source 100 can be illuminated simultaneously to output white light.

[0049] It should be noted that in order to enhance the brightness of the light source, a yellow primary color is sometimes added to the three primary colors. The yellow primary color light can be produced by superimposing red light and green light. Therefore, when the four colors are output sequentially by controlling the red, green and blue lasers, there can actually be a period when the two primary colors are output at the same time, that is, red and green have an overlapping period, which is used to control the output of the yellow primary color.

[0050] Figure 4-1 Shown Figure 3 Schematic diagram of the optical engine structure of a laser projection device. Specifically, it includes a light source 100, an optical engine 200, and a lens 300. The three are connected together by structural components, and the optical path is sealed within the shell structure.

[0051] Figure 4-2 A schematic diagram of the decomposed structure of an optical engine structure is shown. Schematically, the light beam emitted by the light source 100 passes through a diffuser wheel 140 and then enters the light rod 210. The diffuser wheel 140 can diverge the angle of the laser beam through the action of a diffuser, creating a variety of divergence angles, thereby playing a role in eliminating speckles. The light rod 210 is a homogenizing component with a rectangular light entrance surface and a light exit surface. After the laser beam enters the light rod, it undergoes multiple reflections based on the principle of total internal reflection, which can also homogenize the energy distribution of the light spot. By setting the area of ​​the light exit and light entrance surfaces, the divergence angle of the beam is constrained. The light exit surface of the light rod 210 and the light entrance surface of the light valve 220 are conjugate to each other. Therefore, it can be understood that the light exit surface of the light rod is the object plane, and the light entrance surface of the light valve is the image plane. The light beams at the light entrance and exit surfaces of the light rod 210 satisfy the Lagrange invariant law, that is, the integral value of the incident angle and area of ​​the light beam at the light entrance surface is equal to the integral value of the incident angle and area of ​​the light exit surface. In this way, the incident angle and the size of the light spot at the light entrance surface of the light rod determine the beam index of the light beam in the subsequent optical path.

[0052] Figure 6-1 Shown Figure 3 A light source structure in a laser projection device. Figure 6-1 As shown, the light source unit 100 of the laser projection device 10 includes a housing 150 and a laser assembly 110 . The light source unit 100 is a three-color laser light source, and the three-color laser beams are emitted from an opening 152 of the light source unit 100 .

[0053] Figure 6-2 for Figure 6-1 Schematic cross-sectional view of the light source structure in FIG. The light source housing 150 has a housing cavity 151, in which the laser assembly 110 and the light combining mirror assembly 120 are at least partially accommodated. The housing cavity 151 has an opening 152 along the light emitting direction of the light source, and a focusing lens 112 is provided at the opening 152 for converging the combined light beam.

[0054] In this example, the laser assembly 110 is a laser that can emit three colors of laser light. Figure 8-1An MCL type laser shown includes a first light-emitting area 1101, a second light-emitting area 1102, and a third light-emitting area 1103 arranged on the same substrate, wherein the first light-emitting area, the second light-emitting area, and the third light-emitting area are arranged adjacent to each other in sequence, and the area of ​​the third light-emitting area is larger than that of the first light-emitting area and the second light-emitting area.

[0055] In a specific implementation, the first light-emitting region may emit blue laser light, the second light-emitting region may emit green laser light, and the third light-emitting region may emit red laser light.

[0056] Figure 8-1 As shown, the above-mentioned three light-emitting areas are located on the same laser package assembly, that is, the light-emitting chips of the three-color laser are arranged in an array and packaged in a module. For example, the MCL-type laser used in this example is a 4X5 light-emitting array. The laser assembly includes a substrate 1110, on which a plurality of light-emitting chips are packaged, and a collimating lens group 1112 is also provided at the light-emitting surface of the laser assembly. The light-emitting surface of the laser assembly has a plurality of light-emitting areas, and the light beams emitted from different light-emitting areas have different colors; one row emits green light, one row emits blue light, and the remaining two rows emit red light. The above-mentioned laser assembly packages the three-color light-emitting chips together, and its volume is relatively small, which is conducive to reducing the volume of the light source device.

[0057] It should be noted that the laser assembly in this example is not limited to the above-mentioned 4X5 array, but can also be other array arrangements, such as a 3X5 array, or a 2X7 array, as long as it can emit three-color laser beams.

[0058] The laser assembly is surrounded by a circuit board parallel to the light-emitting surface of the laser, which provides the laser with a driving control signal, such as Figure 8-2 As shown, the circuit board is a flat structure, with pins 1111 on both sides of the laser. The pins 1111 are respectively welded or plugged into circuit boards 1113a and 1113b on that side which are almost parallel to the plane where the laser is located. 1113a and 1113b can be integrally formed and surround the outside of the laser assembly substrate 1110, or 1113a and 1113b can also be two independent circuit boards, which enclose the laser assembly 110. In this way, the packaged laser assembly can also be regarded as a flat structure, which is easy to install, saves space, and is also conducive to the miniaturization of the light source device.

[0059] like Figure 6-1 and Figure 6-2 As shown, the laser assembly 110 is fixed to the shell 150 by screws, and emits a three-color laser beam into the accommodating cavity inside the light source shell, facing the light-emitting surface of the laser assembly. A light-combining mirror assembly 120 is arranged in the accommodating cavity inside the shell.

[0060] The light combining lens group 120 is provided with a plurality of light combining lenses corresponding to each light emitting area of ​​the laser assembly 110 , and each light combining lens corresponds to a different light emitting area and is used to combine the laser beams from different light emitting areas.

[0061] The light combining mirror assembly 120 combines the light beams from different regions so as to output them from the light outlet of the laser light source. Figure 6-2 As shown, the light-combining lens assembly 120 includes three light-combining lenses 1201, 1202, and 1203, which are sequentially arranged along the optical transmission path of the laser. Different light-combining lenses are arranged on the output light paths of the light-emitting areas emitting corresponding color light beams. Each light-combining lens can reflect the light beams from the corresponding light-emitting areas. The reflected light beams are all along the direction of the laser light source's light outlet, and the light beams of each color are converged to form white light.

[0062] Figure 7-1 A schematic diagram of the optical path of a light source is shown. Multiple light-combining lenses 1201, 1202, and 1203 are each used to make a 90-degree turn of the light beam emitted from the corresponding light-emitting area and then emit it toward the light outlet of the light source. The multiple light-combining lenses are arranged in sequence toward the light outlet of the laser light source, and at least one light-combining lens can transmit the light beams of the corresponding colors of other light-emitting areas and combine them with the reflected light beams, and emit them along the light outlet of the laser light source. The spot sizes of the first-color laser beam and the second-color laser beam are both smaller than the spot size of the third-color laser beam, and the beam angles of the first-color laser beam and the second-color laser beam are different from the angle of the third-color laser beam. Specifically, the parallelism of the first-color laser beam and the second-color laser beam is both smaller than the parallelism of the third-color laser beam, that is, the divergence angle of the third-color laser beam is greater than the divergence angle of the first-color laser beam and the second-color laser beam.

[0063] Among them, the first light-combining lens 1201 is used to receive the light beam emitted from the first light-emitting area, the second light-combining lens 1202 is used to receive the light beam emitted from the second light-emitting area, and the third light-combining lens 1203 is used to receive the light beam emitted from the third light-emitting area. The angles between the light-receiving surfaces of the first light-combining lens 1201, the second light-combining lens 1202, and the third light-combining lens 1203 and the first color laser beam, the second color laser beam, and the third color laser beam emitted from the light-emitting area of ​​the laser assembly 110 can all be set to 45°±2°. Among them, the first light-combining lens 1201 is a reflector, and the second light-combining lens 1202 and the third light-combining lens 1203 are both dichroic mirrors. The first light-combining lens 1201, the second light-combining lens 1202, and the third light-combining lens 1203 are arranged parallel to each other.

[0064] First light-emitting region 1101 emits a first-color laser beam, and first light-combining lens 1201 functions as a reflector for reflecting the first-color laser beam. In one embodiment, the first-color laser beam is collimated by the collimating lens assembly upon exiting laser assembly 110 and can be considered a parallel or nearly parallel beam. This nearly parallel beam can still be considered a parallel or nearly parallel beam after being reflected by first light-combining lens 1201.

[0065] Furthermore, the second light-emitting region 1102 emits a second-color laser beam, and the second light-combining lens 1202 is configured to reflect the second-color laser beam and transmit the first-color laser beam, serving as a dichroic mirror. In one embodiment, the second-color laser beam is collimated by the collimating lens assembly upon exiting the laser assembly 110 and can be considered a parallel or nearly parallel beam. This nearly parallel beam can still be considered a parallel or nearly parallel beam after being reflected by the first light-combining lens 1201.

[0066] As well as Figure 7-1 As shown, the third light emitting area 1103 emits a third color laser, and the third light combining lens 1203 is used to reflect the third color laser beam and transmit the first color and second color laser beams. The third light combining lens 1203 is a dichroic mirror. Figure 11 As shown, the third light-combining lens 1203 has a first surface 1203a and a second surface 1203b, wherein the first surface 1203a has a raised microstructure, which is the incident surface of the first color laser beam and the second color laser beam. After the first color laser beam and the second color laser beam are transmitted through the raised microstructure, they are diverged to a certain extent due to the scattering effect of the microstructure, so that the beam angles of the first color laser beam and the second color laser beam are expanded.

[0067] In a specific embodiment, the raised microstructures are microstructures with random distribution and random particle size, so that the divergence angles of the first color laser beam and the second color laser beam are also random.

[0068] In a specific embodiment, the cross-section of the raised microstructures may be semicircular, triangular, arc-shaped, or platform-shaped, and the microstructures may be arranged regularly, such as in rows and columns.

[0069] Furthermore, the microstructure may also be an irregular granular structure.

[0070] Through the microstructure setting in the above specific embodiment, the beam angles of the first color laser beam and the second color laser beam are increased by 2° to 8°, and the spot sizes of the first color laser beam and the second color laser beam are still within the spot size range of the third color laser beam.

[0071] As well as Figure 11As shown, the second surface 1203b of the third light-combining lens is a planar reflective surface. After the laser beam of the third color is reflected by the second surface 1203b, it is emitted toward the light outlet of the light source. Moreover, after the laser beams of the first color and the second color are transmitted through the first surface 1203a, they are also emitted toward the light outlet of the light source.

[0072] In the MCL packaged laser of this example, the third color laser beam is a red laser beam, which is two rows or two columns. The third light-combining lens is used to receive two rows of red laser beams. Its size is larger than that of the first light-combining lens and the second light-combining lens, so that it can receive all the beams transmitted and reflected from the second light-combining lens.

[0073] In this example, the third light-emitting area 1103 emits two laser beams of the third color, the first light-emitting area 1101 emits one laser beam of the first color, and the second light-emitting area 1102 emits one laser beam of the second color. When these three laser beams of color illuminate the third light-combining lens 1203, preferably, the first and second laser beams of color enter the third light-combining lens 1203 between the two laser beams of the third color. The third light-combining lens 1203 is positioned near the light-emitting port.

[0074] Figure 7-1In the light source shown, the first color is blue, the second color is green, and the third color is red. The size of the red laser light-emitting chip is larger than the size of the blue laser and green laser light-emitting chips, and the fast and slow axis divergence angle range of the red laser is larger than the fast and slow axis divergence angle range of the blue laser and green laser. For example, the size of the red laser light-emitting chip is about 300 μm, while the size of the blue laser light-emitting chip and the green laser light-emitting chip is about 70 μm. In addition, the slow axis divergence angle of the red laser is about 10 to 15 degrees, and the fast axis divergence angle is about 30 degrees, while the fast and slow axis divergence angle range of the blue laser and the green laser is about 7 to 10 degrees. The collimating lens group of the laser assembly 110 is an integrated lens combination. The collimation capability of each lens can be considered consistent, but the divergence angles of the three colors of lasers are not the same. Therefore, when three laser beams with different divergences are collimated through the same collimating lens, the collimation effects are also different. For example, the collimation effects of blue lasers and green lasers are similar, but because the red laser has a larger divergence, the parallelism of its collimated beam is less than that of the blue laser and the green laser. Therefore, the beam angle of the third color laser beam is greater than the angle of the first color and second color laser beams. And the third color laser beam is two laser beams, so the spot area of ​​the third color laser beam is larger. By placing the position where the second color laser beam and the first color laser beam are incident on the third light-combining lens 1203 between the two third color laser beams, the spot size of the combined beam is only equivalent to the spot size of the original third color laser beam, and the size of the combined beam will not increase due to the combination of beams of three color spot sizes.

[0075] And, in Figure 7-1 In the light source shown, the first surface of the third light-combining lens 1203, that is, the incident surface of the first color laser beam and the second color laser beam, has a raised microstructure, so that the beam angles of the first color and second color laser beams after transmission can be expanded respectively. In this way, the beam angles of the first color laser beam and the second color laser beam after transmission and expansion are closer to the third color laser beam, so that when the three colors of laser beams are combined, the uniformity of the combined light spot is better.

[0076] Figure 9-1 and Figure 9-2 A comparative example is given. The applicant found in practice that Figure 9-1 In the embodiment, when the first light combining mirror 1201 and the second light combining mirror 1201 are both reflected by a flat reflective surface, and the incident surface and the reflective surface of the third light combining mirror 1203 are also flat, the beam angles of the first color laser beam and the second color laser beam after being transmitted are both similar to the angles emitted from the light exiting surface of the laser assembly 110. When the three colors of laser light are combined by the third light combining mirror 1203, the light spot on the incident surface of the light rod is analyzed, as shown in FIG. Figure 9-2 As shown in the figure, the spot distribution measured at the incident surface of the light rod shows a clear inner and outer color boundary. For example, the converging spot is approximately circular, with the outermost circle appearing red, followed by purple, blue, and other concentric circles inward. This phenomenon shows that the three colors of laser beams have a spot boundary and uneven color distribution.

[0077] and Figure 7-1 In the light source structure shown, since a raised microstructure is provided on the first surface of the third light-combining lens, it has a certain beam expanding effect on the first color laser beam and the second color laser beam, thereby increasing the spot area of ​​the two beams, thereby making the light spots of the first color laser beam and the second color laser beam overlap better with the light spot of the third color laser beam, which can reduce or eliminate the color boundary phenomenon of the combined light spot, and the color uniformity of the combined light spot is also better.

[0078] In one specific implementation, the raised microstructure can be a diffuser adhered to the first surface of the third light-combining lens, or the raised microstructure can be particles coated on the first surface of the third light-combining lens, or the raised microstructure can be formed on the first surface of the third light-combining lens by photolithography.

[0079] And, as a variation of the above embodiment, Figure 7-5 As shown, a diffuser may be provided before the first and second color laser beams enter the third light-combining lens. Specifically, diffuser 1204 may be provided between the second and third light-combining lenses. Diffuser 1204 may have a single-sided or double-sided microstructure to diffuse the light beams passing therethrough. This allows the third light-combining lens 1203 to utilize a conventional dichroic mirror, reducing manufacturing complexity.

[0080] And, as another variation of the above embodiment, it is also possible to Figure 7-6 As shown, before the first color laser beam and the second color laser beam enter the first light combining lens 1201 and the second light combining lens 1202 respectively, a diffusion sheet is set, and the diffusion sheet is set parallel to the first light exit area and the second light exit area, so that the first color laser beam and the second color laser beam are first diffused and then respectively reflected by the first light combining lens and the second light combining lens. In this example, the diffusion angle of the diffusion sheet is set to be less than Figure 7-5 The diffusion angle of the diffuser shown in .

[0081] In one or more of the above embodiments of the present application, by causing the first color laser beam and the second color laser beam to be incident on the last light-combining lens, the beam angles of the first color laser beam and the second color laser beam can be increased, thereby increasing the area of ​​the spot size so that the beam angle is closer to the third color laser beam with a larger beam angle, and the light spots of the first color laser beam and the second color laser beam are both superimposed within the light spot size of the third color laser beam, thereby alleviating the color boundary phenomenon of the three-color laser spot after light combination, and improving the color uniformity and brightness of the combined light spot. The light source in the above example can provide a high-quality combined light beam.

[0082] And, in Figure 7-1 Based on the light source examples provided, Figure 7-2 Another example of a light source is provided.

[0083] In this example, the first color laser beam, the second color laser beam, and the third color laser beam are all linearly polarized lights.

[0084] The polarization directions of the first and second color laser beams are the same, and are different from the polarization direction of the third color laser beam. In one embodiment, the first color is green, the second color is blue, and the third color is red. The red laser beam is P-polarized, and the blue and green laser beams are both S-polarized, resulting in a 90-degree difference in polarization direction.

[0085] In this example, the blue laser light emitting area 1102 and the green laser light emitting area 1101 are adjacently arranged. The blue laser and the green laser emitted by the laser assembly both pass through the phase retarder 1304 and then enter the light combining lens assembly 120 .

[0086] The phase delay plate 1304 is arranged to face the light beams of the blue laser emitting area and the green laser emitting area, and is located in the output light paths of the blue light and the green light and before it enters the light combining lens assembly 120 .

[0087] A phase retarder corresponds to a wavelength of a certain color. The thickness of the crystal growth affects the degree of phase change of the transmitted light beam. In this example, the phase retarder is a half-wave plate, also known as a λ½ wave plate. It can change the phase of the light beam of the corresponding color wavelength by π, or 180 degrees, and rotate the polarization direction by 90 degrees, for example, changing P light to S light, or vice versa.

[0088] After passing through the half-wave plate, the light originally in the P polarization direction becomes the light in the S polarization direction, such as Figure 10 As shown, the two polarization directions are perpendicular to each other.

[0089] The phase delay plate 1304 is fixed inside the light source housing 150 by clamping and fixing, and does not block the light path.

[0090] The phase delay plate is specifically a half-wave plate, which is arranged between the light-emitting surface 1101 of the green light emitting area of ​​the laser, the light-emitting surface 1102 of the blue light emitting area and the first light-combining lens 1201 and the second light-combining lens 1202.

[0091] Specifically, the half-wave plate is arranged parallel to the light-emitting surfaces of the green light-emitting area 1101 and the blue light-emitting area 1102 of the laser. The half-wave plate is a single piece, and its size can be consistent with the size of the light-emitting surface of the green light-emitting area 1101 and the blue light-emitting area 1102, so that all two colors of light beams can be received.

[0092] In this example, the first light-combining lens 1201 reflects the green light transmitted through the half-wave plate, the second light-combining mirror 1202 transmits the green light and reflects the blue light transmitted through the phase delay plate 1304, and the third light-combining lens 1203 transmits the green light and the blue light and reflects the red light, so that the three primary color light beams are all output in the same direction, i.e., the direction of the opening of the light source housing, and are combined to form a mixed light beam.

[0093] As well as Figure 6-1 As shown, a diffuser 140 is also provided in the light output path of the light source. This diffuser 140 is positioned on the light output path of the focusing lens. The light beam, diffused by diffuser 140, enters a light homogenization component (not shown). Diffuser 140 can be a rotating diffuser, forming a diffuser wheel structure. This rotational diffusion can despeckle the light beam, improving beam quality and reducing the speckle effect in the projected image. The diffused light beam then enters the light homogenization component, which can be a light rod or a fly-eye lens assembly.

[0094] In one specific embodiment, the half-wave plate 1304 is a single piece. Preferably, the half-wave plate is set to correspond to the wavelength of the green laser. Therefore, after the green laser passes through the half-wave plate, its polarization direction is rotated 90 degrees, changing from the original S light to the P light. After the blue laser passes through the half-wave plate, because the wavelength of the half-wave plate does not correspond to the blue wavelength setting, the polarization direction of the blue laser is not deflected by 90 degrees, but is close to the P polarization direction. Of course, a setting corresponding to the wavelength of the blue laser can also be selected. In this case, after the blue laser passes through the half-wave plate, its polarization direction is rotated 90 degrees, changing from the original S light to the P light, while the polarization direction of the green laser changes by nearly 90 degrees.

[0095] And, in one specific implementation, Figure 7-3The light source shown has two phase retarders, specifically half-wave plates 1301 and 1302, which can be configured for the wavelengths of the green and blue lasers, respectively, thereby changing the polarization directions of both the green and blue lasers by 90 degrees, converting them into P light. Alternatively, the half-wave plate can be single, but divided into two coating regions, one for the green laser emitting area and the other for the blue laser emitting area. This is equivalent to providing half-wave plates with corresponding wavelengths for the blue and green lasers.

[0096] When two half-wave plates or two coated areas are used, they are respectively positioned in the output optical paths of the blue laser and the green laser. Specifically, half-wave plate 1301 is positioned in the optical path of the green laser entering the first light-combining lens 1201, and half-wave plate 1302 is positioned in the optical path of the color laser entering the second light-combining lens 1202. When each half-wave plate is positioned for a different color beam, a more accurate phase delay can be achieved for that wavelength, compared to a method of using the same half-wave plate for phase delay for both blue and green lasers. This results in green and blue polarized light with a P-polarization direction close to the theoretical value.

[0097] For different wavelengths, the same optical lens has comparable transmittance for P and S light of different wavelengths, and also comparable reflectance for both P and S light. The optical lens here includes not only the aforementioned beam shaping component—the focusing lens—but also the lens group in the illumination light path within the optical engine, and the refractive lens group within the lens unit. Therefore, when the laser light beam passes through the entire projection optical system, this difference in transmittance and reflectance is the result of the combined effects of the entire system and becomes more pronounced.

[0098] Before adding a half-wave plate, especially when the primary color light is P-light or S-light polarized light, the optical system's optical lenses have a significant selective transmission of P-light and S-light. This causes local chromatic unevenness in the projected image, thereby reducing the quality of the projected image.

[0099] In this embodiment, by arranging a half-wave plate in the light output path of the blue laser and the green laser, especially when a half-wave plate of corresponding wavelength is arranged for the blue laser and the green laser respectively, the polarization direction of the blue laser and the green laser can be changed by the same deflection angle. In this example, the polarization direction of the S light is changed to the P light polarization direction, which is consistent with the polarization direction of the red laser. Therefore, when passing through the same optical imaging system and reflected into the human eye through the projection screen, the transmittance of the blue laser and the green laser that have become P polarized light in the optical lens of the optical system is equivalent to the transmittance of the red laser that is P light, and the consistency of the light processing process is close. Therefore, the polarity is unified before the three-color laser is combined. In this way, when the three-color laser is combined, the transmittance difference of the light beam caused by different polarities can be reduced, and since the beam angles of the blue laser and the green laser are increased, the beam angles are also closer to the beam angles of the red laser, and the spot sizes of the three-color laser beams are also close to each other. The overlap of the combined light spots of different color lasers is high, and the color uniformity is better. In one or more of the above embodiments, it is ensured that the light beam in the system has lower light loss. On the other hand, the color uniformity of the combined light spot is also better. After such a light beam is modulated by the light valve and projected by the lens, the uniformity of the color and brightness of the projected image is improved, and the display quality of the projected image is also higher.

[0100] Since the transmittance of optical lenses to P-polarized light in an optical system is usually greater than the transmittance to S-polarized light, and the reflectivity of the projection screen used in this example to P-polarized light is also greater than the reflectivity to S-polarized light, therefore, by converting the S-polarized blue laser and green laser into P-polarized light, the red, green and blue lasers are all P-light, which can improve the light transmission efficiency of the projection light beam in the entire system, improve the brightness of the entire projection screen, and improve the quality of the projection screen.

[0101] As a variation of the above embodiment, in this example, the blue laser and the green laser are first combined and then combined with the red laser. In this case, a phase retarder, specifically a half-wave plate, can also be set in the optical path of the blue laser and the green laser before they are combined with the red laser. Specifically, the half-wave plate 1304 can also be set between the second light-combining lens 1202 and the third light-combining lens 1203, and can transmit the combined blue laser and green laser beams emitted from the second light-combining lens 1202. In this case, the half-wave plate 1304 is not zoned, but is coated according to the wavelength of a color.

[0102] As well as Figure 7-4In another light source example shown, unlike the previous embodiment, a phase retarder 1303 is positioned in the light output path of the red laser beam before it is combined with the blue and green laser beams. For example, it is positioned between the red laser emitting region 1103 and the third light combining lens 1203.

[0103] Half-wave plate 1303 is set to correspond to the wavelength of the red laser. Similarly, half-wave plate 130R can rotate the polarization direction of the red laser by 90 degrees, changing the red laser from P polarization to S polarization. In this way, the polarization directions of the blue laser, green laser, and red laser are also consistent.

[0104] The above solution of adding phase delay plate is to Figure 7-1 The light source structure shown in the figure is modified based on the above description. Similarly, the above solution can also be applied to Figure 7-5 , Figure 7-6 The same technical effect can also be achieved in the light source solution shown, which will not be described in detail here.

[0105] In the above embodiment of the present application, a laser assembly emitting three colors is used, and the laser light-emitting chips of the three colors are arranged in rows or columns. The wavelength of the first color and the wavelength of the second color are both smaller than the wavelength of the third color. The first color laser beam and the second color laser beam are adjacent to each other, and the first color laser beam and the second color laser beam are both reflected and then combined with the third color laser beam. After the first color laser beam and the second color laser beam are transmitted and scattered by the raised microstructure, the beam angle increases, and the difference in angle with the third color laser beam decreases. The spot size of the first color laser beam and the second color laser beam is also closer to the spot size of the third color laser beam. Therefore, when the three-color laser beam is combined, the overlap of the different color spots is improved, the phenomenon of spot aperture boundary is reduced or eliminated, and the color uniformity is also improved. At the same time, the brightness uniformity can also be improved accordingly, which also improves the display quality of the projected image.

[0106] Furthermore, in the above example, the polarization characteristics of laser beams of different colors vary, which affects the efficiency of beam processing in the optical lens and is prone to localized chromatic unevenness, a phenomenon that is more prominent in ultra-short-throw projection equipment. By placing a half-wave plate in the optical path before combining the three-color laser beams, the polarity of one type of laser beam is changed, so that the polarization polarity of the three-color laser beams of different colors is consistent. This is then combined, resulting in lower light loss and guaranteed color uniformity in the combined light spot.

[0107] In summary, in the examples of one or more laser projection devices provided in this application, the beam angles of laser light beams of different colors are different. By increasing the beam angle of the laser light beam with better beam parallelism, it is equivalent to expanding the beam, and reducing the difference in the beam angle of the laser light beam with slightly worse beam parallelism. In this way, the overlap of the light spots of laser light beams of different colors is improved, thereby improving the color uniformity of the combined light spot, which can improve the display quality of the projected image.

[0108] At the same time, in the examples of one or more laser projection devices provided in the present application, the polarization polarities of laser beams of different colors are different. By setting a half-wave plate in the path before the laser beams of different colors are combined, the polarity of the corresponding laser beam is changed, so that the polarization polarities of the three-color laser beams are consistent. In this way, the light processing efficiency of the combined light spot is highly consistent, which reduces the brightness loss, is also conducive to improving the uniformity of the color and brightness of the combined light spot, and improves the display quality of the projected image.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A laser light source, characterized in that: include: A light source housing having a receiving cavity; A laser assembly, comprising a first light emitting area, a second light emitting area, and a third light emitting area on a light emitting surface of one of the laser assemblies, and emitting a first color laser beam, a second color laser beam, and a third color laser beam, respectively, facing the accommodating cavity of the light source housing, wherein a divergence angle of the third color laser beam is greater than a divergence angle of the first color laser beam and the second color laser beam, and a spot area of ​​the first color laser beam and the second color laser beam is smaller than a spot area of ​​the third color laser beam; A light-combining lens group is arranged in the accommodating cavity, facing the light-emitting surface of the laser assembly; the light-combining lens group includes a first light-combining lens, a second light-combining lens, and a third light-combining lens arranged on the output light path of the light-emitting area that emits the corresponding color laser light beam, and corresponds to the first light-emitting area, the second light-emitting area, and the third light-emitting area, respectively; wherein, at least one of the first light-combining lens, the second light-combining lens, and the third light-combining lens is a dichroic lens, and the one light-combining lens is used to reflect the laser light beam emitted by the light-emitting area corresponding to it, and is also used to pass through the light beams of corresponding colors of other light-emitting areas and combine them with the light beams reflected by them, and emit them along the light outlet direction of the laser light source.

2. The laser light source according to claim 1, wherein: The laser assembly includes a substrate and a plurality of light-emitting chips, which are arranged in an array, with one row emitting blue laser, one row emitting green laser, and two rows emitting red laser.

3. The laser light source according to claim 1 or 2, characterized in that: The first color is blue, the second color is green, and the third color is red.

4. The laser light source according to claim 1 or 2, characterized in that: The outer side of the laser in the laser assembly is surrounded by a circuit board parallel to the light emitting surface thereof. Both sides of the laser are provided with pins, and the pins are welded or plugged into the circuit board.

5. The laser light source according to claim 1, wherein: in, The first light-combining lens is used to reflect the first color laser beam to the second light-combining lens; the second light-combining lens is used to transmit the first color laser beam and reflect the second color laser beam to the third light-combining lens; the third light-combining lens is used to transmit the first color laser beam and the second color laser beam, and reflect the third color laser to the laser light source outlet.

6. The laser light source according to claim 1 or 5, characterized in that: The first color laser beam and the second color laser beam further pass through a diffusion plate before being combined with the third color laser beam.

7. The laser light source according to claim 3, characterized in that The first color laser beam, the second color laser beam, and the third color laser beam are all linearly polarized light, and the polarization directions of the first color laser beam, the second color laser beam, and the third color laser beam are different; Wherein, the first color laser beam and the second color laser beam pass through a half-wave plate before being combined with the third color laser beam; or, The third color laser beam passes through a half-wave plate before being combined with the first color laser beam and the second color laser beam.

8. The laser light source according to claim 7, characterized in that The accommodating cavity has an opening along the light emitting direction of the light source, a focusing lens is arranged at the opening, and a diffusion portion is arranged on the light emitting path of the focusing lens.

9. The laser light source according to claim 8, characterized in that The diffusion part is a rotating diffusion sheet.

10. The laser light source according to claim 8, characterized in that The light beam diffused by the diffusion part is incident on a light homogenizing component, which includes a light rod or a fly-eye lens group.

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