CN112114475B

CN112114475B - Laser projection device

Info

Publication number: CN112114475B
Application number: CN201910888577.3A
Authority: CN
Inventors: 邢哲; 崔雷; 戴洁
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2019-06-20
Filing date: 2019-09-19
Publication date: 2022-10-21
Anticipated expiration: 2039-09-19
Also published as: CN112114476A; CN112114476B; CN112114475A

Abstract

The invention provides a laser projection device, which comprises: the laser device comprises a whole machine shell, a three-color laser light source, an optical machine and a lens; the optical machine is connected with the lens and arranged along a first direction of the whole machine shell; a light source and a radiating fin are arranged in a space enclosed by the optical machine, the lens and part of the whole machine shell along a first direction, a plurality of circuit boards and a second fan are also arranged in the space enclosed by the optical machine, the lens and the other part of the whole machine shell, and the second fan is arranged close to the inner side of the whole machine shell; along the direction vertical to the first direction, a cold air exhaust and a first fan are arranged between one side of the radiating fin and part of the integral shell, and a lens is arranged on the other side of the radiating fin; the first fan blows airflow to the lens from the cold row and the radiating fins in sequence, the airflow flows through the circuit boards and is exhausted out of the whole machine shell through the second fan.

Description

Laser projection device

Technical Field

The invention relates to the technical field of laser projection display, in particular to laser projection equipment.

Background

The laser source has the advantages of good monochromaticity, high brightness, long service life and the like, and is an ideal light source. With the increase of the power of laser devices, the requirements of industrial applications are met, and the lasers are also gradually used as light sources for illumination. For example, in recent years, a laser is used as a projection light source in a projection apparatus, instead of mercury lamp illumination, and the laser also has advantages of a small etendue and high brightness compared to an LED light source.

The lasers are classified into a blue laser, a red laser and a green laser according to the kind of light emission, and emit the blue laser, the red laser and the green laser, respectively. In a monochromatic or bicolor laser light source structure, a fluorescent wheel is usually included, which generates heat during wavelength conversion due to absorption of laser light energy, and the light beam output by the light source is output to a light valve optical modulation device, the size of the light valve is usually small, but the light energy of the whole projection light source is borne, and there is a large thermal conversion. The heat of the laser projection equipment needs to be reasonably and timely dissipated.

Especially in three-color laser projection devices, components such as color wheels are not provided, the most important heat source concentrates the light source part of the three-color laser, the packaging structure of the laser tends to be miniaturized, and the luminous power is continuously improved, wherein the thermal power of the laser is equal to the electric power minus the luminous power. Different lasers have different temperature characteristics, so that the heat dissipation requirements of the lasers are different.

Simultaneously, if for the increase heat-sinking capability, satisfy the inside different heat dissipation demands of laser projection equipment, the rotational speed of fan promotes the problem that will bring the equipment noise undoubtedly, influences the use and experiences.

Disclosure of Invention

The invention provides laser projection equipment, which comprises a three-color laser light source and can carry out economical and effective heat dissipation on the laser projection equipment.

The invention provides a laser projection device: the laser device comprises a whole machine shell, a three-color laser light source, an optical machine and a lens; the optical machine is connected with the lens and arranged along a first direction of the whole machine shell; a light source and a radiating fin are arranged in a space enclosed by the optical machine, the lens and part of the whole machine shell along a first direction, a plurality of circuit boards and a second fan are also arranged in the space enclosed by the optical machine, the lens and the other part of the whole machine shell, and the second fan is arranged close to the inner side of the whole machine shell; a cold air outlet and a first fan are arranged between one side of the radiating fin and part of the integral shell along the direction vertical to the first direction, and a lens is arranged on the other side of the radiating fin; the first fan blows airflow to the lens from the cold row and the radiating fins in sequence, and the airflow flows through the circuit boards and is exhausted out of the whole shell through the second fan;

furthermore, a light valve of the optical machine is provided with a radiator, a fourth fan is arranged at the radiator, the fourth fan blows airflow to the circuit boards from the radiator and discharges the second fan out of the whole machine shell;

furthermore, one side surface of the light source is connected with the radiating fin through a heat pipe; the light source is provided with a first light outlet which is connected with the optical machine, the other side surface of the light source opposite to the first light outlet is connected with a cold head, and the cold head is communicated with the cold row through a pipeline;

further, a third fan is arranged between the other side of the radiating fin and the lens, and blows airflow in the direction of the radiating fin to the lens;

furthermore, at least 2 second fans are arranged in parallel along the inner side of the whole machine shell;

further, the light source comprises a light source shell, and a red laser component arranged on the light source shell is connected with the cold head; a blue laser component and a green laser component are respectively arranged on the side surface of the light source shell opposite to the radiating fin; the blue laser component and the green laser component are connected with the heat pipe and conduct heat to the radiating fins;

further, a heat sink on the back of the red laser assembly is in contact with the cold head through a first heat conduction block, wherein the area of the first heat conduction block is larger than that of the contact surface of the cold head;

further, the temperature of the cold head is greater than that of the cold row, and the difference value is 1-2 ℃;

furthermore, the blue laser assembly and the green laser assembly are connected with a plurality of heat pipes through heat conducting blocks and are connected with the radiating fins through the heat pipes;

furthermore, the heat pipes are a plurality of straight heat pipes, and a plurality of channels are arranged inside the radiating fins and used for accommodating the heat pipes;

further, the operating temperature of the red laser assembly is less than 50 ℃, and/or the operating temperature of the blue laser assembly and the green laser assembly is less than 65 ℃;

further, the first fan is arranged between the cold row and the whole machine shell, or the first fan is arranged between the cold row and the radiating fins.

The laser projection equipment of one or more embodiments provides a laser projection equipment, the whole structure layout is compact, the heat dissipation airflow can flow from the part with the lower working temperature threshold value to the part with the higher working temperature threshold value by blowing the heat dissipation airflow from the optical part to the circuit part, and the heat dissipation airflow can sequentially dissipate heat for a plurality of heat source parts in one heat dissipation path, so that the working heat dissipation requirements of the heat source parts can be met, meanwhile, the whole heat dissipation efficiency is high, and the heat dissipation mode is economical and effective.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1A is a schematic structural diagram of a laser projection apparatus according to an embodiment of the present invention;

fig. 1B is a schematic view of a complete machine heat dissipation structure of a laser projection apparatus according to an embodiment of the present invention;

FIG. 1C is a schematic diagram of an optical path of a laser projection apparatus according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating a DLP projection architecture according to an embodiment of the present invention;

fig. 3A is a schematic diagram of an ultra-short focus projection imaging optical path in an embodiment of the present invention;

FIG. 3B is a schematic diagram of an ultra-short-focus projection system in accordance with an embodiment of the present invention;

FIG. 4A is a diagram of a structure of an ultra-short-focus projection screen according to an embodiment of the present invention;

FIG. 4B is a diagram illustrating the reflectivity of the projection screen of FIG. 4A relative to the projection beam;

FIG. 5A is a schematic diagram of a light source structure of the laser projection apparatus shown in FIG. 1A according to an embodiment of the present invention;

FIG. 5B is an exploded view of FIG. 5A;

FIG. 5C-1 is a schematic view of a laser module assembly according to an embodiment of the present invention;

FIG. 5C-2 is a schematic view of another laser assembly in accordance with an embodiment of the present invention;

FIG. 5D is an exploded view of a laser assembly in accordance with an embodiment of the present invention;

FIG. 5E-1 is an exploded view of another laser assembly in accordance with an embodiment of the invention;

FIG. 5E-2 is an exploded view of another laser assembly in accordance with an embodiment of the present invention;

FIG. 5F-1 is a schematic diagram of an MCL laser;

FIG. 5F-2 is a schematic diagram of a laser circuit package structure of FIG. 5F-1;

FIG. 5G is a schematic diagram of an optical path of a light source according to an embodiment of the present invention;

FIG. 5H is a schematic diagram of an optical path of another light source according to an embodiment of the invention;

FIG. 5I is a schematic view of another angle light source according to an embodiment of the present invention;

FIG. 6A-1 is a diagram of a heat dissipation system for a light source according to an embodiment of the present invention;

FIG. 6A-2 is an exploded view of a portion of a heat dissipation system of a light source according to an embodiment of the invention;

FIG. 6B is a schematic diagram of a heat dissipation path a according to an embodiment of the present invention;

FIG. 6C is a schematic view of a heat dissipation system of a red laser module according to an embodiment of the present disclosure;

FIG. 6D is a schematic diagram of a heat dissipation system for blue and green laser assemblies in an embodiment of the present invention;

FIG. 6E is an exploded view of the heat removal system for the blue and green laser assemblies in an embodiment of the present invention;

FIG. 7 is a schematic diagram of a red laser chip;

FIG. 8A is a schematic diagram illustrating an optical path principle of a laser projection system according to an embodiment of the present invention;

FIG. 8B is a schematic diagram illustrating an optical path of another laser projection system according to an embodiment of the present invention;

fig. 9A is a schematic view of a diffusion sheet structure according to an embodiment of the invention;

FIG. 9B is a schematic diagram showing the energy distribution of the laser beam after passing through the diffuser shown in FIG. 9A according to the embodiment of the present invention;

FIG. 10 is a schematic diagram of a light spot in the light path according to an embodiment of the present invention;

FIG. 11A is a schematic view of an optical axis of a wave plate;

FIG. 11B is a schematic diagram of a 90 degree change in linearly polarized light;

FIG. 11C is a schematic view of the P and S light polarization directions;

FIG. 11D is a schematic diagram of a wave plate rotation arrangement;

FIG. 12A is a schematic diagram of an optical path in an embodiment of the invention;

FIG. 12B is a schematic diagram of another optical path in an embodiment of the present invention;

FIG. 12C is a schematic diagram of an optical path according to another embodiment of the present invention;

FIG. 12D is a schematic diagram of an optical principle of a laser projection apparatus according to an embodiment of the present invention;

description of reference numerals:

10-laser projection device, 101-housing;

100-light source, 102-light source housing, 1021-window, 1022-air pressure balancing device, 1023-adjusting structure mounting location, 103-first light outlet, 104-fixing support, 1041-light-transmitting window, 1042-third sealing element; 105-sealing glass, 1051-first seal, 1052-second seal, 106-first light-combining mirror, 107-second light-combining mirror, 108-third light-combining mirror, 109-homogenizing element, 110-red laser assembly, 111-converging mirror set, 112-diffusing plate, 120-blue laser assembly, 130-green laser assembly, 121, 131, 140, 141, 151-half-wave plate;

1101-a collimating lens group, 1102-a metal substrate, 1103-a laser pin, 1104a, 1104b-a PCB;

200-optical machine, 201-second light inlet, 202-third light outlet, 210-illumination light path, 220-DMD digital micro-mirror array, 230-vibrating mirror, 240-heat sink, 250-light receiving component, 260-diffusion wheel;

300-lens, 310-refractive lens group, 320-reflector group;

400-projection screen, 401-substrate layer, 402-diffusion layer, 403-uniform medium layer, 404-Fresnel lens layer, 405-reflection layer;

500-a circuit board;

601-radiating fins, 602-heat pipes, 603-heat conducting blocks, 604-first fans, 605-second fans, 606-third fans, 607-fourth fans, 610-cold heads, cold rows-611, liquid replenishers-612, 613-heat conducting blocks.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

First, the structure and operation of the laser projection apparatus according to the present embodiment will be described with reference to the laser projection apparatus shown in fig. 1A.

Fig. 1A shows a schematic structural diagram of a laser projection apparatus, where the laser projection apparatus 10 includes a whole casing 101, and further includes a light source 100, an optical machine 200, and a lens 300 according to optical functional portions, where the optical portions are wrapped by corresponding casings and achieve a certain sealing or airtight requirement, for example, the light source 100 is hermetically sealed, which can better prevent the light attenuation problem of the light source 100. The light source 100, the optical engine 200 and the lens 300 are installed in the whole casing 101. The optical engine 200 and the lens 300 are connected and disposed along a first direction of the whole casing 102, as shown in fig. 1A, the first direction may be a width direction of the whole casing, or the first direction is opposite to a viewing direction of a user according to a use mode. The light source 100 is disposed in a space enclosed by the optical engine 200, the lens 300 and a part of the whole casing 101. The light source 100 is a pure three-color laser light source that emits red, blue, and green laser light.

Referring to fig. 1A and 5B, the light source 100 has a first light outlet 103, the optical engine 200 has a second light inlet 201 and a third light outlet 202, and the second light inlet 201 and the third light outlet 202 are located on different sides of the optical engine in a vertical relationship according to the design of the internal illumination light path of the optical engine, where the vertical relationship is a vertical relationship in a spatial position relationship, and the different sides may be different sides of the housing of the rectangular optical engine or different sides of the irregular three-dimensional structure. The first light outlet 102 of the light source 100 is connected to the second light inlet 201 of the optical engine 200, and the light beam of the light source 100 enters the optical engine 200, passes through the illumination light path inside the optical engine 200 to reach the light modulation device, and is output to the lens 300 by the light modulation device.

Fig. 1C shows a schematic diagram of an optical path of a laser projection apparatus, which is shown as being divided into a light source 100, an optical engine 200, and a lens 300 according to optical functional parts. The light source 100 includes a three-color laser module and a plurality of optical lenses for homogenizing and beam-reducing the laser beam. The light beam emitted from the light source 100 is incident into the optical engine, and a light guide tube is usually located at the front end of the optical engine for firstly receiving the illumination light beam of the optical engine, and the light guide tube has the functions of light mixing and homogenization. The optical machine also comprises a plurality of lens groups to form an illumination light path, the illumination light path is incident to a key core device, namely a light valve, and the light valve modulates the light beam and then the light beam is incident into the lens groups of the lens to be imaged.

Specifically, the optical bench 200 includes a light modulation device, which is a core component of the system. The light modulation devices (also called light valves) can be classified into liquid crystal light valve LCDs, liquid crystal on silicon LCOS, and DMD digital micromirror chips. Wherein the DMD chip is applied to the DLP projection architecture.

Fig. 2 shows a DLP (Digital Light Processing) projection architecture, in which a DMD (Digital Micromirror Device) Digital Micromirror array is a core Device of the entire projection architecture. The monolithic DMD application will be described below as an example. The DMD220 is a reflective light valve device, and the illumination light beam output from the light source portion generally needs to pass through the illumination light path 210 at the front end of the DMD220, and after passing through the illumination light path 210, the illumination light beam conforms to the illumination size and the incident angle required by the DMD 220. The DMD220 surface includes thousands of tiny mirrors, each of which can be individually driven to deflect, such as plus or minus 12 degrees or plus or minus 17 degrees in a DMD chip provided by TI. The light reflected by the positive deflection angle is called ON light, the light reflected by the negative deflection angle is called OFF light, and the OFF light is invalid light and generally hits ON the housing or is absorbed by a light absorption device. The ON light is an effective light beam that is irradiated by the illumination light beam received by a tiny mirror ON the surface of the DMD light valve and is incident ON the lens part 300 through a positive deflection angle, and is used for projection imaging.

In this example, the light engine 200 applies a DLP projection architecture and uses DMD reflective light valves as light modulation devices.

Referring to fig. 1A, the lens 300 is connected to the optical engine 200 through the third light outlet 202, and the specific connection may be through the end surfaces of the respective housings locked by screws, wherein a part of the lens group of the lens 300 further extends into the third light outlet 202 of the optical engine 200.

The lens portion 300 includes a multi-lens assembly, which is generally divided into a front group, a middle group, and a rear group, or a front group and a rear group, wherein the front group is a lens group near the light emitting side of the projection apparatus, and the rear group is a lens group near the light emitting side of the light modulation device. According to the above combination of various lens sets, the lens portion 300 may also be a zoom lens, or a fixed-focus adjustable lens, or a fixed-focus lens.

The laser projection device of the present example is an ultra-short-focus projection device, and therefore the lens portion 300 is an ultra-short-focus projection lens, and the projection ratio thereof is generally less than 0.3, such as 0.24. The ultra-short-focus projection lens can be one of the examples shown in fig. 3A, and includes a refractive lens group 310 and a mirror group 320, the mirror group 320 can be a curved mirror, as shown in fig. 3B, the projection light beam passes through the lens portion 300 and then obliquely exits to the projection screen 400 for imaging, which is different from the light exiting mode in which the optical axis of the projection light beam is located at the perpendicular bisector of the projection image in the conventional long-focus projection, and the ultra-short-focus projection lens generally has an offset of 120% to 150% with respect to the projection image.

Since the size of the DMD chip is very small, such as the current DMD chip provided by TI has 0.66 inch, 0.65 inch, and 0.47 inch, and the size of the projection screen is usually over 70 inches, such as between 80 inches and 150 inches, for the lens portion 300, not only hundreds of times of amplification is realized, but also aberration is corrected, and the resolution is good, so as to present a high-definition projection screen, and the design difficulty of the ultra-short focus projection lens is much greater than that of the long focus projection lens.

In the ultra-short focus projection device, the central perpendicular of the light exit surface of the DMD light valve is generally parallel to the optical axis of the lens, but is not coincident with the optical axis, i.e. the DMD is offset from the lens portion 300, the light beam emitted from the light exit surface of the DMD is obliquely incident into the lens portion 300 at a certain angle, passes through the transmission and reflection of partial areas of the plurality of lenses, and finally the projected light beam is obliquely emitted from the lens portion 300 upwards.

The DMD is used as a light modulation device and is driven by an electric signal to modulate light, so that the light beam carries image information and is finally amplified by the lens part to form a projected image.

On the basis of the relatively fixed resolution of the DMD itself, in order to realize an image picture with higher definition and resolution, as shown in fig. 3A, a vibrating mirror 230 may be further disposed in the path from the exit light path of the DMD to the lens, where the vibrating mirror 230 is a transmissive plain film structure. Through one-dimensional vibration, the galvanometer carries out angular displacement on image light beams which are transmitted successively, so that two adjacent images can be imaged on a projection screen after being subjected to dislocation superposition, the information superposition of the two images becomes image information by utilizing the effect of human eye vision persistence, the image details perceived by human eyes are increased, and the resolution of the images is also improved.

The galvanometer can also move in two dimensions, for example, four positions of the galvanometer are moved up, down, left and right, so that four images can be overlapped in a staggered mode, and the resolution improving effect sensed by human eyes is achieved by utilizing the principle of information quantity overlapping. No matter two images or four images are superposed, the two sub images or the four sub images are obtained by decomposing an image with high resolution in advance, and the decomposition mode needs to be matched with the motion mode of the galvanometer so as to be correctly superposed without the confusion of the images.

The galvanometer is usually arranged between the DMD light valve and the lens, light beams transmitted between the DMD and the lens can be approximately regarded as parallel light beams, the parallel light beams can still keep good parallelism after being refracted by the plain film, but if light beams with larger divergence angles are refracted by the plain film, the refracted angle change is larger, and uneven brightness or chrominance can be caused when two image light beams sequentially passing through the galvanometer are superposed.

Referring to fig. 1A, a plurality of circuit boards 500 are disposed in a space enclosed by the optical engine 200, the lens 300 and another part of the whole casing 101, the plurality of circuit boards 500 include a power board, a TV board, a control board, a display board, etc., the plurality of circuit boards 500 are generally stacked, or a part of the plurality of circuit boards 500 may be disposed along a bottom surface of the whole casing 101 and a part thereof may be disposed along a side surface of the whole casing.

And, in the laser projection apparatus 10, along the inside of the whole body case 101, structures such as a sound, a fan, a heat sink, and the like are further provided.

In the laser projection apparatus provided by the above embodiment, the optical engine 200 and the lens 300 are disposed along the first direction of the apparatus casing 101, and the apparatus is divided into two parts, one part can accommodate the light source, and the other part can accommodate the circuit board, which are respectively the left part and the right part as shown in fig. 1A. Such a division can be considered as separating the optical part and the electrical part. Although the optical part is also provided with a driver circuit in general, since the circuit parts such as the signal board, the power supply board, and the like are smaller in size and less complicated than the display board, the left half body can be considered as the optical part and the right half body as the circuit part. The different main bodies are separately arranged, so that the assembly and debugging of the whole machine are facilitated, and the respective design requirements of the optical part and the electrical part, such as heat dissipation, routing, electromagnetic testing and the like, are facilitated.

Moreover, in the laser projection apparatus provided in this example, the optical engine 200 and the lens 300 are disposed in the same direction, and a part of the lens group of the lens 300 extends into the optical engine 200, which is beneficial to reducing the volume of the optical engine and the lens after the two parts are assembled. And according to the light emitting characteristics of the reflective light valve, although the light beam of the light source 100 may be turned multiple times and finally enter the lens 300 due to different illumination light path architectures, the direction of the light beam emitted from the first light outlet 103 of the light source 100 and the direction of the light beam entering the lens 300 may be considered to have a perpendicular relationship in spatial position with respect to the direction of the light beam of the light source 100 and the direction of the light axis of the lens 300. The light source 100, the optical engine 200, and the lens 300 are connected and assembled to form an L-shape, which provides a structural basis for turning of the optical axis of the light beam, and not only reduces the difficulty in designing the optical path of the optical engine 200 incident to the lens 300. The laser projection equipment is compact in overall layout and simpler in light path architecture.

Therefore, in the present example, the light source 100 is used to provide light source illumination for the light engine 200, and specifically, the light source 100 provides illumination beams for the light engine 200 by outputting three primary color illumination beams in time sequence and synchronously.

The light source 100 may also be output in a non-time-sequential manner, and there are superimposed output periods of different primary colors, for example, red and green have superimposed output periods, which increases the proportion of yellow in a light beam period, and is beneficial to improving the brightness of an image, or red, green, and blue are simultaneously lit up in a part of periods, and three colors are superimposed to form white, so that the brightness of a white field can be improved.

And when other types of light modulation components are applied, in order to match with the three-piece type LCD liquid crystal light valve, the three primary colors of light in the light source part can be simultaneously lightened to output mixed white light. In this example, although the light source unit 100 outputs three primary colors in a time sequence, the human eye cannot distinguish the colors of light at a certain time and still perceives mixed white light according to the principle of mixing three colors. The output of the light source section 100 is also commonly referred to as mixed white light.

Fig. 5A is a schematic partial structure diagram of the light source 100 in fig. 1A, and fig. 5B is an exploded structure diagram of fig. 5A. An example of the three-color laser light source will be described below with reference to the drawings.

As shown in fig. 5A, the light source 100 includes a light source housing 102, and a red laser assembly 110, a blue laser assembly 120, and a green laser assembly 130 mounted on different sides of the light source housing 102 to emit red laser light, blue laser light, and green laser light, respectively. The blue laser assembly 120 and the green laser assembly 130 are mounted on the same side surface in parallel, and are both perpendicular to the red laser assembly 110 in a spatial position, that is, the side surface of the light source housing where the blue laser assembly 120 and the green laser assembly 130 are located is perpendicular to the side surface of the light source housing where the red laser assembly 130 is located, and both the two side surfaces are perpendicular to the bottom surface of the light source housing 102 or the bottom surface of the whole housing 101.

Referring to fig. 5G, which is a schematic diagram of an optical path of the light source 100, as shown in fig. 5G, the blue laser assembly 120 and the green laser assembly 130 are arranged in parallel, wherein the blue laser assembly 120 is disposed close to the red laser assembly 110, and the green laser assembly 130 is disposed far away from the red laser assembly 110. The light-emitting surface of the red laser element 110 faces the light-emitting port of the light source, i.e., the light beam emitted from the red laser element 110 can be directly output to the light-emitting port of the light source 100 without turning the light path.

The light beam emitted by the green laser component is emitted from the light outlet after three times of reflection, and the light beam emitted by the blue laser component is emitted from the light outlet after one time of transmission and one time of reflection. It can be seen that, in the schematic diagram of the above optical path principle, the optical path through which the red laser passes is the shortest, the optical path through which the green laser passes is the longest, and the reflection times through which the green laser passes are the greatest.

Referring to fig. 5A and 5B, the laser assemblies of any color output rectangular spots, and are vertically mounted on the side surface of the light source housing 102 along the long side direction of the respective rectangular spots. Therefore, laser spots output by the three-color laser assembly cannot form cross-shaped spots when light is combined, and the reduction of the size of the light combination spots and the higher homogenization degree are facilitated.

As shown in fig. 5B, the light source housing 102 includes a plurality of side surfaces, a bottom surface and a top cover, and the plurality of optical lenses of the light source 100 are disposed on the bottom surface of the light source housing 102. In order to increase the heat dissipation area, the top cover of the light source housing 102 is fin-shaped. A plurality of windows 1021 are formed on the side surface of the light source housing 102 to mount the laser components, and light beams emitted by the laser components of any color enter the internal cavity of the light source 100 through the corresponding mounting windows to form a light transmission path through a plurality of optical lenses.

In this example, some control circuit boards (not shown) are further mounted on the top cover of the light source housing 102, and as shown in fig. 5I, the structure view from the bottom surface of the light source housing is further reserved with an adjusting structure mounting position 1023 of the optical lens.

And, as shown in fig. 5I, an air pressure balancing device 1022 is further disposed on the bottom surface or the top cover of the light source housing 102. The air pressure balancing device 1022 may be a filter valve, and may be used to communicate the inside of the light source with the outside, so as to realize the exchange of air flows, when the temperature of the inside of the light source rises, the inside air flows outwards, and when the temperature recovers to cool, the outside air flows also into the inside of the light source. Or the air pressure balancing device is a telescopic air bag which can be made of elastic rubber and is used for relieving the air pressure of the cavity in the light source by increasing the volume when the air pressure of the cavity in the light source is increased. The air pressure balancing device can be used as a pressure relief device, when the temperature of the cavity in the light source is too high, the air pressure of the cavity in the light source can be balanced by communicating the pressure relief device outwards or increasing the volume of the sealed space of the cavity in the light source through forming the air containing structure, and the working reliability of each optical device in the cavity in the light source is improved.

Since the three-color laser module and the light source housing have substantially the same assembly structure, for the sake of convenience of describing the connection relationship between the laser module and the light source housing, the following description will take the assembly structure of any one of the laser modules as an example.

The three-color laser assembly is an MCL type laser assembly, namely a plurality of light-emitting chips are packaged on one substrate to form surface light source output. As shown in fig. 5F-1 and 5F-2, the MCL laser includes a metal substrate 1102, and a plurality of light emitting chips (not shown) are packaged on the metal substrate 1102, and the light emitting chips may be connected in series or may be driven in parallel according to rows or columns. The plurality of light emitting chips may be arranged in a 4X6 array, or may be arranged in other arrays, such as a 3X5 array, a 2X7 array, a 2X6 array, or a 4X5 array, where the overall light emitting power of the lasers in different numbers of arrays is different. Pins 1103 extend from both sides of the metal substrate 1102, and the pins are electrically connected to each other, whereby the light emitting chip can be driven to emit light. Covering the light-emitting face of the MCL laser, there is also provided a collimating lens group 1101, the collimating lens group 1101 being fixed, typically by gluing. The collimating lens set 1101 includes a plurality of collimating lenses, which generally correspond to the light emitting positions of the light emitting chips one by one to collimate the laser beams correspondingly.

As shown in fig. 5F-2, the MCL-type laser assembly further includes

PCB boards

1104a,1104b disposed at the outer periphery of the MCL laser, and

PCB boards

1104a,1104b are parallel to or in the same plane as the light-emitting surface of the laser, so as to drive the laser pins 1103 and provide driving signals for the laser. As shown in the figure, the circuit board is a flat structure, the two sides of the laser have pins 1103, the pins 1103 are respectively welded or plugged on the

circuit boards

1104a and 1104b on the side which is almost parallel to the plane where the laser is located, wherein the

pins

1104a and 1104b can be integrally formed and surround the outer side of the laser component substrate 1102, or the

pins

1104a and 1104b can also be two independent circuit boards, and the two circuit boards surround the laser component.

Fig. 5C-1 and 5D are an assembly structure diagram and an exploded structure diagram of the laser module of any color and the fixing bracket, respectively.

As shown in fig. 5B, the laser module of any color is mounted at the window 1021 of the corresponding light source housing through the fixing bracket 104, and the fixing bracket 104 and the light source housing 102 are locked by screws, so as to fix the laser module at the position of the window 1021. The laser assembly of any color comprises an MCL laser assembly and a fixed bracket.

The laser component of any color is locked on the fixing support through a screw, and specifically, the metal substrate of the MCL type laser is provided with an assembling hole which can be locked with the fixing support.

As shown in fig. 5D, the fixing bracket 104 is a sheet metal part having a light-transmitting window 10211, the front surface of the light-transmitting window 1401 of the fixing bracket 104 is installed near the window 1021 of the light source housing 102, and the laser module of any color is installed at the installation position of the back surface of the light-transmitting window 10211 of the fixing bracket. In addition, in order to improve the sealing performance of the mounting structure, a third sealing member 1042 is disposed at the mounting position on the back side of the light-transmitting window 10211 of the fixing bracket, and the third sealing member 1042 has a frame-shaped rubber member with a folded edge, which can be sleeved on the front side of the MCL-shaped laser and then fix the MCL-shaped laser assembly at the mounting position. The third sealing member 1042 can also play a role of buffering, and prevent the collimating lens group on the surface of the MCL type laser from being damaged due to hard contact with the sheet metal part.

The MCL-type laser assembly is composed of an MCL laser and a corresponding PCB 1104, and the MCL-type laser assembly is fixed on the fixing bracket 104 to form an assembly unit and is installed at a position of the window 1021 corresponding to the light source housing 102. Specifically, there are studs around the window 1021 that are driven into the studs around the window by screws through the studs of the fixing bracket.

Because the light source 100 is internally provided with a plurality of optical lenses which are precise components, and the energy density in the light beam transmission process is very high, if the cleanliness of the internal environment is not high, dust and dust particles can be accumulated on the surfaces of the precise lenses, so that the light processing efficiency is reduced, the light attenuation of a light path is further caused, and the brightness of the whole laser projection equipment is also reduced accordingly. In this example, the light attenuation problem may be reduced by preventing dust inside the light source, and specifically, as shown in fig. 5E-1, a sealing glass 105 is further disposed at the window 1021, and the sealing glass 105 isolates the cavity inside the light source from the laser module installed at the window 1021, so that external dust and the like may not enter the cavity inside the light source from the window opening. The sealing glass 105 may be disposed on the surface of the inner cavity of the light source, for example, by bonding, or may be disposed on one side of the light source housing close to the laser module, for example, by disposing an installation position on the outer surface of the light source housing, and the laser module and the sealing glass are sequentially disposed outside the window of the light source housing.

As shown in the exploded structure of fig. 5E-1, the sealing glass 105 is mounted on the side of the window 1021 near the laser module in this example for the convenience of the sealing glass mounting described above. The front surface of the fixing bracket 104 further has a first receiving groove for receiving the first sealing member 1051, and the window 1021 of the light source housing has a second receiving groove for receiving the second sealing member 1052. The sealing glass 105 is located between the first sealing member 1051 and the second sealing member 1052, specifically, the second sealing member 1052 is placed in the second accommodating groove at the window 1021, a matching fixing groove with the sealing glass 105 is arranged in the second sealing member 1052, the sealing glass 105 is placed in the fixing groove, the first sealing member 1051 is installed in the first accommodating groove of the fixing support light transmission window 10211 through interference fit, then any color laser assembly composed of the fixing support and the MCL laser assembly is installed at the window 1021 of the light source housing, the first sealing member 1051 is in pressing contact with the sealing glass 105, and the sealing glass 105 is clamped between the first sealing member 1051 and the second sealing member 1052 for fixing along with the fixing completion of the laser assembly.

In the above examples, the MCL-type laser module of any color is fixed to the fixing bracket by the shoulder screw, and the shock absorbing member is further provided between the shoulder screw and the fixing bracket, so that noise transmission generated during the driving of the laser at a high frequency can be reduced.

The assembly structure of the laser module and the light source housing is explained above. The laser component is arranged on the light source shell, emits laser beams under the control of a driving signal, forms light path output inside, and performs projection imaging by matching with an optical machine and a lens.

In a laser projection apparatus, a light source is a main heat generating source, and a high-density energy beam of a laser irradiated on the surface of an optical lens also generates heat. The DMD chip has an area of a fraction of an inch, but is required to withstand the beam energy required for the entire projected image, and the heat generation is very high. On the one hand, the laser has the operating temperature who sets for, forms stable light output, compromises life and performance, and simultaneously, equipment is inside to contain a plurality of precision optical lens, and especially ultrashort burnt camera lens contains a plurality of lenses, if whole equipment inside high temperature, the heat gathering can cause the lens to take place "the temperature and float" the phenomenon in the camera lens, and imaging quality can seriously descend. And components such as circuit board devices are driven by electric signals, certain heat is generated, and each electronic device has a set working temperature. Therefore, good heat dissipation and temperature control are very important guarantees for proper operation of the laser projection device.

Referring to the schematic structural diagram of the laser projection apparatus shown in fig. 1B, in a space enclosed by the optical engine 200, the lens 300, and a part of the whole apparatus housing 101, a light source 100 and a heat dissipation fin 601 are sequentially disposed along the same arrangement direction as the optical engine and the lens. The light source 100 is disposed near one side of the casing, and the heat dissipation fin 601 is disposed near the other side of the casing 101 along the first direction, where the two sides are opposite. The heat sink fins 601 are connected to the opposite light source housing 102 portion by heat pipes, and specifically, in the light source heat sink system schematic shown in fig. 6A-1 and 6A-2, the heat sink fins 601 are disposed opposite to the sides of the blue laser assembly and the green laser assembly mounted on the light source housing. The blue laser assembly and the green laser assembly are connected with the heat dissipation fins 601 through heat pipes, and heat is conducted to the heat dissipation fins 601.

Specifically, as shown in fig. 6D and fig. 6E, the heat conducting block 603 is in contact with the heat sink of the laser assembly for conducting heat, the outer surface of the heat pipe 602 is in contact with the heat conducting block for realizing heat transfer, one end of the heat pipe 602 in contact with the heat conducting block 603 is a hot end, the other end of the heat pipe 602 is in contact with the heat dissipating fins and is a cold end, the heat pipe is a closed system with liquid inside, and heat conduction is realized through liquid-gas change. The cooling fins contacted with the cold end of the heat pipe are cooled by air cooling generally, so that the cold end of the heat pipe is also cooled, and the gas is liquefied and flows back to the hot end of the heat pipe.

As shown in fig. 6A, a cold head 610 is connected to a side surface of the light source housing 102 facing the first light outlet 103 of the light source 100. In this example, a red laser assembly is mounted on a side of the light source housing opposite the first light outlet 103 of the light source 100. The red laser assembly is connected with the cold head 610 and dissipates heat in a liquid cooling manner. In the liquid cooling circulation system, the cold head takes away the heat of the heat source component and returns to the cold row, the cold row is cooled, the cooled cooling liquid, such as water which is commonly used, returns to the cold head again, and the circulation is performed on the heat source in sequence. In the liquid cooling circulation system, the liquid cooling circulation system further comprises a pump for driving the cooling liquid in the liquid cooling circulation system to keep flowing, in this example, the pump and the cold head are integrally arranged, so that the reduction of the size of the components is facilitated, and the cold head mentioned below can refer to an integrated structure of the cold head and the pump. And in the liquid cooling circulation system of the laser projection equipment of the example, the liquid replenishing device is further included and is used for replenishing liquid to the liquid cooling circulation system, so that the liquid pressure in the whole liquid cooling circulation system is greater than the external pressure of the system, and therefore external gas cannot enter the inside of the circulation system due to volatilization of cooling liquid or poor tightness of a pipe joint, the internal noise of the circulation system is avoided, and even cavitation phenomenon is generated to damage devices.

Compared with an air cooling heat dissipation system, the liquid cooling circulation system is flexible, the volume of the cold head and the cold row is smaller than that of the traditional heat dissipation fin, and the selection of the shape and the structure position of the liquid cooling circulation system is more diversified. Because the cold head and the cold row are communicated through the pipeline and are a circulating system all the time, the cold row can be arranged close to the cold head and also can have other relative position relations, and the space of the laser projection equipment determines the cold row.

In this example, as shown in fig. 6B, the cold row 611 and the liquid replenisher 612 are both arranged close to the side of the whole machine housing, and the volume of the cold row 611 is larger than that of the liquid replenisher 612 and the cold head 610, so that the liquid replenisher 612 and the cold head 610 are arranged at one position, and the cold row 611 are arranged in parallel inside the whole machine housing.

A plurality of circuit boards 500 and a plurality of second fans 605 are further disposed in a space enclosed by the optical engine 200, the lens 300 and another part of the whole casing, the second fans 605 are disposed near the whole casing 101, and the number of the second fans may be multiple.

As shown in fig. 1B, the laser projection apparatus of the present example has two main heat dissipation paths, path a and path B, depending on the air flow direction. The heat of the DMD chip, which is the core component of the optical engine, is conducted along the path a, and the heat of the light source 100 is mainly conducted along the path b.

In the above laser projection apparatus, the light source 100 is disposed at the left side of the entire apparatus, the optical engine 200 and the lens 300 are located at the middle of the apparatus, and the circuit board is disposed at the right side of the apparatus. The air flow flows from left to right along both path a and path b, the main path of which is substantially parallel.

In a laser projection device, the light source 100 is a laser light source, and the laser components of different colors included have different operating temperature requirements. Wherein the working temperature of the red laser assembly is less than 50 ℃, and the working temperature of the blue laser assembly and the working temperature of the green laser assembly are less than 65 ℃. The working temperature of the DMD chip in the optical machine is usually controlled to be about 70 ℃, and the temperature of the lens part is usually controlled to be below 85 ℃. And the temperature control of different electronic devices is different for the circuit board part, and is generally between 80 ℃ and 120 ℃. Therefore, because the tolerance values of the optical component and the circuit part in the equipment to the temperature are different, and the working temperature tolerance value of the optical part is generally lower than that of the circuit part, the airflow is blown to the circuit part from the optical part, so that the two parts can achieve the purpose of heat dissipation and maintain the normal work of the two parts.

As for the path a, as shown in fig. 6B, the path a is located in the upper half of the device, mainly takes away heat of the light valve in the optical engine 200, and flows through a part of the circuit board, and is exhausted outside the housing through the second fan. The light valve DMD chip dissipates heat through the heat sink 240, the heat sink 240 dissipates heat through the fourth fan 607 by air cooling, and the air flow flows through a part of the circuit boards along the path a, the second fan 605 is an induced-draft fan, and the flow direction of the air flow formed by the fourth fan 607 is the same as that of the air flow formed by the fourth fan 607, so that the air flow formed by the fourth fan 607 can still have the flow speed after flowing through the heat sink and a plurality of circuit boards, and the hot air can be smoothly discharged out of the whole case.

For path B, shown in FIG. 1B, it is in the lower half of the device. In the laser projection apparatus shown in fig. 1B, the cold row 610 and the heat dissipation fins 601 are sequentially arranged along the direction of the path B, and one side of the heat dissipation fins 601 is the cold row 610 and the other side is the lens 300. In order to timely dissipate heat of the cold row 610 and the heat dissipation fins 601, a first fan 604 is arranged between the cold row 610 and the heat dissipation fins 601, the first fan 604 is an air suction fan for the cold row 610, and is an air blowing fan for the heat dissipation fins 601, the fan sucks away the heat of the cold row to form a first air flow, and blows the first air flow to the heat dissipation fins 601, the heat dissipation fins 601 are provided with multiple groups of parallel air channels, the first air flow passes through the surfaces of the heat dissipation fins and the internal air channels to form a second air flow, the second air flow blows to the lens 300, and the second air flow can flow along the periphery of the lens 300 shell and the bottom space of the lens 300 shell to take away the heat on the surface of the lens shell.

It should be noted that, because the operating temperature of the red laser component is less than 50 ℃, for example, when the operating temperature is controlled to be below 45 ℃, a liquid cooling heat dissipation manner is used, and the difference between the surface temperature of the cold row and the surface temperature of the cold head is controlled to be in the range of 1~2 ℃, that is, if the surface temperature of the cold head is 45 ℃, the surface temperature of the cold row is 43 ℃ to 44 ℃, wherein the surface temperature of the cold head refers to the temperature of the contact surface between the cold head and the laser component heat sink. Specifically, the first fan sucks in air at an ambient temperature, the ambient temperature is usually 20 to 25 ℃, the cold air is cooled and radiated to the cold row, and the surface temperature of the cold row is reduced to 43 ℃. The working temperature of the blue laser component and the green laser component is below 65 ℃, the temperature of the heat dissipation fins needs to be 62-63 ℃, and the temperature difference between the temperature of the heat dissipation fins and the temperature of the heat sink of the laser component is 2~3 ℃. It can be seen that the temperature of the cold row is lower than the temperature of the heat dissipating fins, and therefore, the cold row is disposed at the front end of the heat dissipating path and is also located in front of the heat dissipating fins in the heat dissipating path. The air flow formed by the rotation of the fan dissipates heat of the cold row and blows the cold row to the radiating fins again, and the radiating fins can still dissipate heat.

Similarly, the working temperature of the lens is controlled to be 85 ℃, the temperature of the radiating fins is controlled to be 63 ℃, and the temperature is still lower than the working temperature of the lens, so that the second air flow flowing through the radiating fins is still cold air flow relative to the lens, and heat dissipation can be utilized. The working temperature of the circuit board is generally higher than the working control temperature of the lens, so that the airflow after the heat dissipation of the lens is still cold airflow relative to most of the circuit boards, and can still continuously flow through the circuit boards for heat dissipation.

In the path b, because there are many heat source components needing heat dissipation, the resistance of the airflow flowing is also large, in order to enhance the flow velocity, so that the hot airflow in the path is quickly dissipated out of the whole housing, a second fan 605 is further arranged on the airflow outflow side of the circuit board and close to the whole housing, the second fan 605 drives the airflow to flow through the cold row 610, the heat dissipation fins 601, the lens 300 and the circuit board 500 together through the first fan 604, and the heat dissipation path b is formed.

It should be noted that the first fan may also be disposed at the front end of the cold row, that is, the first fan may be disposed between the complete machine casing and the cold row. At this time, the first fan is a blowing fan relative to the cold row, and at this time, the wind blown by the first fan is blown to the cold row first and then to the heat dissipation fins.

And, the airflow can take away heat when flowing, in order to increase the flow rate of the heat dissipating airflow, as shown in fig. 6A-2, a third fan 606 may be further disposed between the heat dissipating fins and the lens, and the third fan 606 is an air suction fan for the heat dissipating fins 601 and an air blowing fan for the lens 300, which is equivalent to accelerating the second airflow, increasing the flow rate and enhancing the heat carrying capability, and in cooperation with the air suction of the second fan 605, the third fan 606 blows the second airflow to the circuit board and discharges the second airflow out of the housing through the second fan.

In the heat dissipation path a or the heat dissipation path b, the airflow basically flows in a linear shape and rarely has roundabouts and turns, which can reduce the resistance of the airflow flow, facilitate the airflow to quickly flow away at a faster flow speed after carrying heat, and facilitate the heat dissipation of the heat source component.

In this example, the cold row, the heat dissipation fins, the lens and the circuit board have gradually-increased working temperature thresholds, the structural layout mode is also favorable for designing a heat dissipation path, the heat dissipation airflow can flow from the part with the lower working temperature threshold to the part with the higher working temperature threshold, heat dissipation can be performed on a plurality of heat source parts in sequence in one heat dissipation path, the working heat dissipation requirements of the heat source parts can be met, and meanwhile, the heat dissipation efficiency of the whole machine is high.

In another embodiment, the cold row may also be disposed in the heat dissipation path a, and the circuit board is located in the same heat dissipation path as the DMD chip.

In another embodiment, the heat dissipation fins can increase the heat dissipation capacity by performing structural modification on the fin surface to increase the heat dissipation area or increase the flow velocity of wind in order to increase the heat transfer coefficient.

In the laser projection apparatus provided in the above embodiment, the emission power range of the red laser package may be 24w to 56w, the emission power range of the blue laser package may be 48w to 115w, and the emission power range of the green laser package may be 12w to 28w. Preferably, the red laser assembly has an emission power of 48W, the blue laser assembly has an emission power of 82W, and the green laser assembly has an emission power of 24W. The three-color laser adopts the MCL type laser assembly, and compared with the BANK type laser, the three-color laser has the advantage that the volume is greatly reduced under the condition of outputting the same luminous power.

As described above, in the laser projection apparatus, the heat dissipation requirement of the light source 100 is the most strict, and is a portion of the entire apparatus where the operating temperature is relatively low. Specifically, the operating temperature of the red laser assembly is lower than the operating temperatures of the blue laser assembly and the green laser assembly, which is determined by the light emission principle of the red laser. The blue laser and the green laser are generated by using a gallium arsenide light emitting material, and the red laser is generated by using a gallium nitride light emitting material. The red laser has low light emission efficiency and high heat generation. The temperature requirements of the red laser luminescent material are also more stringent. Therefore, when the light source component composed of the three-color laser is radiated, different radiating structures are required to be arranged according to the temperature requirements of different laser assemblies, the laser of each color can be ensured to work in a better state, the service life of the laser assemblies is prolonged, and the light emitting efficiency is more stable.

The air cooling heat dissipation mode can control the temperature difference between the hot end and the cold end of the heat source to be about 3 ℃, and the temperature difference control of the liquid cooling heat dissipation can be more accurate and smaller in range, such as 1~2 ℃. The red laser component with the lower working temperature threshold value adopts a liquid cooling heat dissipation mode, the blue laser component with the relatively higher working temperature threshold value and the red laser component adopt an air cooling heat dissipation mode, the red laser component can be cooled by lower heat dissipation cost under the condition of meeting the requirement of the working temperature of the red laser, and the requirement on the rotating speed of the fan can be reduced by meeting the requirement on the smaller temperature difference. But the cost of the components of the liquid cooling heat dissipation method is higher than that of the air cooling heat dissipation method.

Therefore, in the laser projection device in the example, the mode of liquid cooling and air cooling mixed heat dissipation is adopted for the heat dissipation of the light source, so that the working temperature control of different laser assemblies can be met, and the laser projection device is economical and reasonable.

Specifically, referring to fig. 6C, the metal substrate on the back of the red laser assembly 110 is connected to the cold head through the first heat conduction block 613, the area of the first heat conduction block 613 is larger than that of the heat conduction surface of the cold head, and the area of the first heat conduction block is also larger than that of the heat sink heat conduction surface on the back of the red laser assembly 110. Therefore, the heat of the heat sink of the laser assembly is quickly concentrated and transferred to the cold head, and the heat conduction efficiency is improved.

In the heat dissipation system configuration shown in FIG. 6C, the outlet of cold head 610 is piped to the inlet of cold row 611, and the outlet of cold row 611 is piped to the inlet of cold head 610. In the liquid cooling circulation system formed by the cold head 610, the cold bar 611 and the pipeline, a liquid replenishing device 612 is further provided, as mentioned above, the liquid replenishing device 612 is used for replenishing cooling liquid for the circulation of the system, so that the liquid replenishing device can be provided with a plurality of positions of the whole circulation system, and according to factors such as the system structural space, the liquid replenishing devices can be one or more, can be connected with the pump, and can also be arranged close to the cold bar.

In this example, the operating temperature control of the blue and green laser assemblies is the same, sharing a single heat sink fin structure. Specifically, as shown in fig. 6D and 6E, the heat sink on the back of the blue laser assembly 120 and the green laser assembly 130 is in contact with the heat pipe 602 through the heat conduction block 603, and the heat pipe 602 extends into the heat dissipation fin 601. For laser assemblies of different colors, for example, for blue laser assemblies, for the sake of convenience of distinction, the heat conduction block 603 is the second heat conduction block, and for green laser assemblies, the heat conduction block 603 is the third heat conduction block. The second heat conduction block and the third heat conduction block can be two independent components, are respectively different laser assemblies for heat conduction, and also can be of a whole structure, so that the installation is convenient, and the heat dissipation requirements of the laser assemblies with two colors are the same, and the temperature can be conveniently controlled.

The heat pipes are a plurality of heat pipes, and preferably, the number of the heat pipes corresponding to the blue laser assembly is the same as that of the heat pipes corresponding to the green laser assembly. In this example, the heat pipe is a straight heat pipe, the number of the heat pipes is multiple, and the heat dissipation fins are provided with a plurality of through holes for inserting the multiple heat pipes. Radiating fin 601 is close to blue and green laser subassembly setting, and many heat pipes can not buckle, and during the disect insertion radiating fin, straight type heat pipe does benefit to the reduction of transmission resistance among the inside gas-liquid change of heat pipe, does benefit to and improves heat conduction efficiency.

Through above-mentioned combination heat radiation structure, can dispel the heat to the light source part to guarantee the normal work of three-colour laser light source part. The light source emits three-color laser, provides high-quality illuminating light beams, and projects to form a projection image with high brightness and good color. Because the three-color laser components are arranged at different spatial positions, a plurality of optical lenses are also needed in the light source inner cavity to combine and homogenize the laser beams in different directions.

In the laser projection apparatus provided in this embodiment, as shown in the schematic diagram of the light path principle of the light source shown in fig. 5G, the green laser light emitted by the green laser assembly 130 is reflected by the first light combining mirror 106 and then enters the second light combining mirror 107, the blue laser light emitted by the blue laser assembly 120 is transmitted through the second light combining mirror 107, and the green laser light is reflected by the second light combining mirror 107 and output, so that the blue laser light and the green laser light can be combined and output through the second light combining mirror 107.

The output direction of the blue laser and the green laser combined and output by the second light combining mirror 107 is perpendicular to the output direction of the red laser emitted by the red laser component 110, and has a junction, a third light combining mirror 108 is arranged at the junction of the three light beams, and the third light combining mirror 108 transmits the red laser and reflects the green laser and the blue laser. After passing through the third light combining mirror 108, the three-color laser beams are combined to form a light beam, which is incident to the homogenizing element 109, and is emitted from the light source light outlet after the light spot is reduced by the converging lens assembly 111.

In the light source configuration shown in fig. 5B, the blue laser assembly 120 and the green laser assembly 130 are mounted side-by-side on one side of the light source housing and the red laser assembly 110 is mounted on the other side of the light source housing 102 in a perpendicular relationship. The three-color laser subassembly all outputs the rectangle facula, and all along the long edge direction of respective rectangle facula, vertical installation is on the side of light source casing.

In the inner cavity of the light source 100, a plurality of light combining mirrors and a converging mirror group are further disposed. Specifically, the first light combining mirror 106 is disposed obliquely toward the light emitting surface of the green laser component 130, and reflects the green laser light to the second light combining mirror 107. The second light combining mirror 107 is disposed obliquely toward the light emitting surface of the blue laser component 120, transmits the blue laser light and reflects the green laser light to the third light combining mirror 108. The first and

second beam combiners

106 and 107 are arranged substantially in parallel and are disposed at an angle of 45 degrees with respect to the light emitting surface of the corresponding laser module. The first combining mirror 106 and the second combining mirror 107 are clamped and fixed on the bottom surface of the light source housing 102 through the base, and the angles of the first combining mirror and the second combining mirror can be adjusted finely, for example, within plus or minus 3 degrees, in consideration of the reason of assembly tolerance.

The third light combining mirror 108 is disposed obliquely toward the light emitting surface of the red laser device assembly 110, where the oblique angle of the third light combining mirror 108 is 135 degrees oblique to the optical axis direction of the red laser, and the third light combining mirror 108 transmits the red laser and reflects the blue and green laser, so as to combine the three-color laser beams to the converging mirror group 111. The third light combining lens 108 is disposed adjacent to the converging lens group 111. Similarly, the third combiner 108 is also fixed on the bottom surface of the light source housing 102 by clamping through a base, and is set to have a fine adjustment angle within 3 degrees.

The first light-combining mirror is a reflecting mirror, the second light-combining mirror and the third light-combining mirror are dichroic sheets.

And the light reflectivity of the second light combining mirror and the third light combining mirror is larger than the light transmissivity thereof, for example, the light reflectivity of the two light combining mirrors can reach 99%, and the transmissivity is usually 95% -97%.

The three-color laser assemblies provided in this example are MCL type lasers, as shown in fig. 5F-1, the MCL laser includes a plurality of light-emitting chips packaged on a metal substrate, and the light-emitting chips with different colors have different light-emitting powers due to different light-emitting principles, for example, the light-emitting power of a green chip is about 1W per chip, and the light-emitting power of a blue chip is more than 4W per chip. When the three-color laser adopts the same number of chips for arrangement, for example, the chips are all packaged in a 4X6 arrangement, and the overall light emitting power is different, for example, the light emitting power of the green laser component is smaller than that of the red laser component and is also smaller than that of the blue laser component, and the light emitting power of the red laser component is smaller than that of the blue laser component.

Meanwhile, in the above-described embodiments, the light emitting chip packages of the red laser assembly and the blue laser assembly and the green laser assembly employ the same array, for example, a 4 × 6 array each. However, due to the difference of the light emitting principle of the red laser, as shown in fig. 7, two light emitting points exist at one light emitting chip, which makes the divergence angle of the red laser in the fast axis direction and the slow axis direction larger than that of the blue laser and the green laser, and in the optical path transmission process, for the red laser passing through the same optical lens, the optical lens has a certain light receiving range or a better light processing performance in a certain angle range due to the large divergence angle, so that the longer the optical path or optical path the red laser passes through, the more serious the divergence degree of the red laser is, and the lower the light processing efficiency of the rear optical lens on the red laser is. Although the light emitting power of the red laser assembly is greater than that of the green laser, the light loss rate of the red laser light is greater than that of the green laser light and the blue laser light after passing through the light path of the same length.

In the light source structure shown in fig. 5B, the light emitting surface of the red laser assembly 110 faces the first light outlet 103 of the light source, and the red laser light is output along the light emitting surface of the red laser assembly, passes through the homogenizing element 109 and the converging lens group 111, and then exits from the first light outlet 103. For the blue laser, the blue laser is transmitted once, and then reflected once, enters the homogenizing element 109 and the condensing lens group 111 and exits from the first light outlet 103, and the green laser is reflected three times, enters the homogenizing element 109 and the condensing lens group 111 and exits from the first light outlet 103. It can be seen that the optical paths of the red laser light are shorter than those of the blue laser light and the green laser light before being output from the first light outlet of the light source, so that the optical loss generated by the red laser light during the optical path transmission can be reduced. And, under the condition that the influence of the optical path on the optical loss is not considered, after the red laser passes through the third light combining mirror, the light energy can reach about 97% × 1=97%, and it should be noted that, in the calculation of the light energy efficiency of the red laser, the influence of the transmittance and the reflectance of the optical lens is only considered when the divergence angle of the red laser is large and the large-angle light loss exists.

And the green laser is reflected for three times, when only the influence of the transmittance on the light loss is considered, the light energy output by the green laser from the third light combining mirror can reach about 99% × 99% =97%, the light energy output by the blue laser from the third light combining mirror can reach about 99% × 97 =96% after the blue laser is transmitted and reflected for one time, and the light path of the blue laser is shorter than that of the green laser, so that the light loss of the blue laser and the green laser after the blue laser is output from the third light combining mirror is basically consistent as viewed from the transmittance loss of the optical element on the light and the loss of the light path on the light for short and short, and the light loss is also equivalent to the light loss of the red laser at the position. Therefore, based on the laser light source layout, under the different optical characteristics of the lasers of all colors, the loss of the laser beams of all colors in the transmission process can be well balanced, the power ratio of the three-color laser is close to a preset value, obvious unbalance cannot occur, and the color ratio which accords with theoretical design and the expected white balance can be favorably realized. When the three-color laser beams are output from the third light combining mirror, the light paths of the three laser beams are the same, and consistent light loss is easily achieved.

And, through the arrangement of above-mentioned three-colour laser subassembly, also be favorable to dispelling the heat to the different heat dissipation demands of red laser subassembly, blue laser subassembly and green laser subassembly. The red laser component is sensitive to temperature, the working temperature is usually controlled below 50 ℃, the working temperature of the blue laser component and the working temperature of the green laser component are higher than that of the red laser component, the blue laser component and the green laser component have obvious temperature difference and are usually controlled below 65 ℃, and therefore, the blue laser component and the green laser component which have the same temperature control requirement are arranged together, and heat dissipation is facilitated through a shared heat dissipation structure. And the red laser assembly is independently arranged at other positions of the light source shell and is separated from the blue laser assembly and the green laser assembly by a certain distance, so that the heat radiation of the blue laser assembly and the green laser assembly serving as high-temperature heat sources to the red laser assembly serving as a low-temperature heat source can be reduced, and the heat burden of the red laser assembly is reduced.

The laser assemblies all adopt MCL type laser assemblies, and compared with the traditional BANK type laser assemblies, the MCL type laser assemblies are obviously smaller in size, so that in the embodiment, as shown in a light source of laser projection equipment shown in figures 1A and 5B, the structural size of the light source is obviously reduced compared with that of the traditional BANK type laser assemblies, more space can be reserved near the light source, convenience is provided for heat dissipation design, for example, a radiator is provided, a fan can be placed on position selection to be more flexible, and structures such as a circuit board can be arranged, the length of the whole machine structure in a certain direction can be favorably reduced, or the size of the whole machine can be favorably reduced.

As a modification of fig. 5G, the positions of the blue laser module and the green laser module may be changed as well as the optical paths shown in fig. 5G, for example, as shown in fig. 5H, the green laser module 130 is disposed facing the second beam combiner 107, and the blue laser module 120 is disposed facing the first beam combiner 106, so that the optical energy loss of the green laser beam is 1-97% × 99% =4%, the optical energy loss of the blue laser module is 1-99% × 99% =3%, and the optical path of the green laser beam is shorter than the optical path of the blue laser beam, so that the optical losses of the green laser beam and the green laser beam are almost the same as each other as a whole.

In the embodiments, the red laser assembly is disposed close to the light outlet of the light source, and the blue and green lasers respectively pass through the turning light path and then are merged with the red laser, the light path of the red laser is shortest, so that the light path transmission light loss of the red laser can be reduced, the red laser only passes through the transmission of the optical element once, and the blue laser and the green laser respectively undergo multiple transflective treatments, so that the loss of the red laser in the transmittance of the optical element is correspondingly lowest, therefore, the light loss of the red laser before the red laser is merged can be reduced as much as possible, the light power and the color ratio of the three-color light source can be maintained, the white balance of the system is close to the theoretical set value, and the high quality of the projection picture can be realized.

Referring to fig. 5B, fig. 5G, and fig. 5H, in the light source of the above-mentioned laser projection apparatus, after the three-color laser light is combined by the light combining lens, the light beam is further homogenized and reduced by the homogenizing element and the converging lens group, so as to improve the light collection efficiency and the homogenization efficiency of the light collecting element in the rear light machine.

Specifically, as shown in fig. 5B, 5G, and 5H, the light source 100 further includes a homogenizing element 109 and a condensing lens group 111. The homogenizing element 109 is disposed between the third light combining mirror 108 and the condensing mirror group 111. Specifically, the homogenizing element can be a diffuser with regularly arranged microstructures, as shown in fig. 9A. The microstructures of the diffusion sheets commonly used at present are random and irregular, the microstructures regularly arranged by the homogenization diffusion sheets used in the light source framework can change the energy distribution of laser beams from a Gaussian shape to a shape shown in fig. 9B similar to the principle that fly-eye lenses homogenize the laser beams, as shown in fig. 9B, the energy near the central optical axis of the laser is greatly weakened and becomes gentle, the divergence angle of the laser beams is also increased, and therefore the effect of homogenizing the energy is greatly superior to the diffusion sheets with the commonly used microstructures irregularly arranged.

The homogenization diffusion sheet can be provided with regularly arranged microstructures on a single surface or double surfaces.

After homogenization by the homogenization diffusion sheet, the laser beam is reduced in spot size by the convergence mirror group. On one hand, the high-energy laser beam is homogenized first, so that impact caused by uneven energy distribution of a rear-end element can be reduced, and on the other hand, the homogenization is performed first, beam contraction is performed, and the difficulty of homogenizing the light spot again after beam contraction can be reduced.

The homogenizing element 109 may be a two-dimensional diffraction element, and may achieve a better homogenizing effect.

In this example, the converging lens group includes two convex lenses, such as a combination of a biconvex lens and a convex-concave lens, both of which are spherical lenses, although both of them may be aspheric lenses, but the spherical lenses are easier to form and control accuracy than the aspheric lenses, and the cost can be reduced. In this example, the converging lens group is used for converging the light beam, and a focal point of the converging lens group is disposed at a light receiving port of the rear light receiving element, that is, a focal plane of the converging lens group is located at a light incident surface of the light receiving element, so as to improve light receiving efficiency of the light receiving element.

As shown in fig. 5B, the converging lens group is located at the first light outlet 103 of the light source housing, specifically, the rear lens or the entire lens group in the converging lens group can be mounted at the first light outlet 103, and the converging lens group 111 and the housing around the first light outlet 103 are filled with a sealing member, such as a sealing rubber ring. Therefore, when the converging lens group is fixed, the airtight sealing of the cavity in the light source can be kept, and dust particles brought in when the first light outlet is used as a light-transmitting window to exchange with external air flow are prevented. And the condensing lens group is directly fixed at the position of the first light outlet, which is also beneficial to shortening the light path and reducing the volume of the light source shell.

The light beam output from the first light outlet of the light source in a convergent state is finally collected by a light-collecting part of an illumination light path of the optical machine. As shown in the schematic diagram of the optical path principle in fig. 8A, in the present example, the light-absorbing part 250 is a light guide. The light guide tube is provided with a rectangular light incident surface and a rectangular light emergent surface. The light guide serves as both a light-absorbing member and a light-uniformizing member. The light incident surface of the light guide is a focal plane of the converging lens group 111, the converging lens group 111 inputs the converged light beam into the light guide 250, and the light beam is reflected for multiple times inside the light guide and exits from the light exiting surface. Because the homogenizing diffusion sheet is arranged in the front-end light path, the light path is homogenized through the light guide pipe, a better three-color mixing and homogenizing effect can be achieved, and the quality of the illuminating light beam is improved.

Because the light source is a pure three-color laser light source, speckle is a phenomenon specific to laser, and in order to obtain higher projection picture display quality, three-color laser needs to be subjected to speckle elimination treatment. In the example, a diffusion wheel 260, i.e. a rotating diffusion sheet, is further disposed between the converging lens group 111 and the light-absorbing member 250. The diffusion wheel 260 is located in the converging light path of the converging lens group 111, and the distance between the wheel surface of the diffusion wheel 260 and the light receiving component 250-the light incident surface of the light guide is about 1.5-3mm. The diffusion wheel can diffuse the light beams in a convergent state, increase the divergence angle of the light beams and increase the random phase. And, because human eyes have different speckle sensitivities to different colors of laser light, the diffusion wheel can be partitioned, such as a first partition and a second partition, wherein the first partition is used for transmitting red laser light, the second partition is used for transmitting blue laser light and green laser light, and the divergence angle of the first partition is slightly larger than that of the second partition. Or, the laser device is divided into three subareas which respectively correspond to the red laser, the green laser and the blue laser, wherein in the three subareas, the divergence angle of the red laser subarea is in a size relationship that the divergence angle of the red laser subarea is the largest, and the divergence angle of the blue laser subarea is the smallest. When the diffusion wheel has corresponding divisions, the rotation period of the diffusion wheel may coincide with the period of the light source. In general, when the diffusion wheel is a single diffusion sheet, the rotation period is not particularly limited.

The light guide tube has a certain light receiving angle range, for example, light beams within a range of plus or minus 23 degrees can enter the light guide tube and be utilized by a rear-end illumination light path, and other light beams with large angles become stray light to be blocked outside to form light loss. The light-emitting surface of the diffusion wheel is arranged close to the light-in surface of the light guide pipe, so that the light quantity of the diffused laser beams in the light guide pipe can be increased, and the light utilization rate is increased.

The light-absorbing member may be a fly-eye lens member.

And, as mentioned above, since the homogenizing diffuser 109 is disposed in the front end light path, the light source beam is homogenized, converged by the converging mirror group 111, and enters the diffuser wheel 260. The laser beam passes through a static diffusion sheet and then passes through a moving diffusion sheet, so that the laser beam is diffused and homogenized again on the basis of homogenizing the beam by the static diffusion sheet, the homogenization effect of the laser beam can be enhanced, the energy proportion of the beam near the optical axis of the laser beam is reduced, the coherence degree of the laser beam is reduced, and the speckle phenomenon presented by a projection picture can be greatly improved.

In the light source provided by the above embodiment, the light beam of the light source is incident on the light pipe to receive and homogenize the light again, and the light spot distribution measured by the applicant on the light incident surface of the light pipe shows a more obvious color boundary phenomenon between the inner circle and the outer circle. For example, the converged light spot is circular, the outermost circle is red, and the light spots are sequentially inward apertures of different concentric circles such as purple, blue and the like. As shown in fig. 10. It has been found through research that, as mentioned above, the red laser assembly has a divergence angle of the fast and slow axes larger than those of the blue laser and the green laser due to the difference of the light emitting principle. Although the three-color laser assembly is arranged in an array of the same number of chips in the present example, the three-color laser assembly has a uniform size in appearance in terms of volume, due to the characteristics of the red laser beam, the spot size of the red laser beam during transmission is larger than those of the blue laser beam and the green laser beam. This combination of three colors is already present, and as the light path transmission distance increases, the divergence angle increases at a greater rate than the other color lasers, so that although the combined three colors will be homogenized, condensed, and possibly further diffused and homogenized by the rotating diffuser, the spot size of the red laser will always be larger. The test light spot on the light incident surface of the light guide tube also shows the phenomenon.

In order to improve the coincidence ratio of the three-color laser spots, the length of the light guide pipe can be increased to improve the light mixing and homogenizing effects, but the light path length is increased, and the structure volume is increased.

In this example, a solution is proposed, specifically, on the basis of the optical path schematic diagrams provided in fig. 5G and fig. 5H, as shown in fig. 8B, a diffusion sheet 112 is disposed in the light combining path of the blue laser beam and the green laser beam, and the blue laser beam and the green laser beam are diverged and then combined with the red laser beam. Wherein the diffusion sheet 112 is arranged in the light path between the second light-combining mirror 107 and the third light-combining mirror 108. It is of course also possible to provide stationary diffusing plates for the blue laser light and the green laser light, for example in the light paths between the light emitting surfaces of the two color laser assemblies and the corresponding light combining mirrors.

Set up a slice diffusion piece in the light path through blue laser and green laser, can expand blue laser and green laser, for example set up to the diffusion angle of 1 degree ~3 degrees, after this diffusion piece, the blue laser and the green laser through expanding the beam carry out the light with red laser again, and the facula size of three-colour laser is equivalent this moment, and facula coincidence degree improves. The three-color light spots with high coincidence degree are beneficial to homogenization and spot dissipation of a subsequent light path, and the light beam quality is improved.

The laser emitted by the laser is linearly polarized light, wherein in the light emitting process of the red laser, the blue laser and the green laser, the oscillation directions of the resonant cavities are different, so that the polarization directions of the red laser linearly polarized light, the blue laser linearly polarized light and the green laser linearly polarized light are 90 degrees, the red laser is P light linearly polarized light, and the blue laser and the green laser are S light linearly polarized light.

In the above embodiment, as shown in fig. 1A and 5B, the light source employs a red laser component and a blue laser component, and the polarization direction of the green laser component is 90 degrees, wherein the red laser is P light, and the blue and green laser are S light. The three-color light beams projected by the laser projection equipment have different polarization directions.

In practical applications, in order to better reduce the original color and contrast, the laser projection apparatus usually needs to be matched with a projection screen with higher gain and contrast, such as an optical screen, so as to better reduce the projection picture with high brightness and high contrast.

An ultra-short focus projection screen is shown in fig. 4A, which is a fresnel optical screen. The device comprises a substrate layer 401, a diffusion layer 402, a uniform medium layer 403, a Fresnel lens layer 404 and a reflection layer 405 along the incident direction of a projection light beam. The thickness of the Fresnel optical screen is usually 1 to 2mm, wherein the thickness proportion occupied by the substrate layer 401 is the largest. The substrate layer is also used as a supporting layer structure of the whole screen, and has certain light transmittance and hardness. The projection beam firstly transmits through the substrate layer 401, then enters the diffusion layer 402 for diffusion, and then enters the uniform dielectric layer 403, which is a uniform transparent medium, for example, the same material as the substrate layer 401. The light beams are transmitted through the uniform medium layer 403 and enter the Fresnel lens layer 404, the Fresnel lens layer 404 converges and collimates the light beams, the collimated light beams are reflected by the reflection layer and then return back to pass through the Fresnel lens 404, the uniform medium layer 403, the diffusion layer 402 and the base material layer, 401 and are incident to the eyes of a user.

In the research and development process, the applicant finds that local color cast occurs on an ultra-short focal projection picture using the three-color laser light source, so that the phenomena of uneven chroma such as 'color spots' and 'color blocks' are caused. The reason for this is that, on one hand, because the polarization directions of the laser beams with different colors are different in the currently applied three-color laser, a plurality of optical lenses, such as lenses and prisms, are usually disposed in the optical system, and the transmittance and reflectance of the optical lenses for P-polarized light and S-polarized light are different, such as the transmittance of the optical lenses for P light is relatively greater than that for S, while, on the other hand, because of the structure of the screen material, the ultra-short focus projection screen itself will show significant changes in transmittance and reflectance for beams with different polarization directions with the change of the incident angle of the ultra-short focus projection beam, as shown in fig. 4B, when the incident angle is about 60 degrees for the red projection beam, through experiments, the reflectivity of the projection screen to the P-type red projection beam and the reflectivity of the projection screen to the S-type red projection beam differ by more than 10 percentage points, that is, the reflectivity of the ultra-short focus projection screen to the P-light is greater than the reflectivity to the S-light, so that more P-light is reflected by the screen to enter human eyes, and the S-light reflected by the screen to enter human eyes is relatively reduced.

In order to solve the above problem, an improvement is made on the light source provided by the above embodiment, and another light source structure embodiment is proposed.

In this embodiment, the blue laser component and the green laser component are disposed adjacent to each other, a phase retarder is disposed in the output path of the blue laser and the green laser and before the blue laser and the green laser are incident on the third combiner, and the polarization directions of the blue laser and the green laser are changed to be the same as the polarization direction of the red laser, so that the color cast phenomenon of the projection image due to the difference in the polarization directions is solved.

First, the operation principle of the phase retarder will be described. The phase retarder is a half-wave plate, also called λ As wave plate, which affects the degree of phase change of the transmitted light beam by the thickness of the crystal growth, and in this example, the phase retarder changes the phase of the light beam corresponding to the color wavelength by π, i.e., 180 degrees, and rotates the polarization direction by 90 degrees, such as changing P light into S light or changing S light into P light. As shown in fig. 11A, the wave plate is a crystal, the crystal has its own optical axis W, and is located in the plane of the wave plate, and the wave plate is disposed in the optical path and perpendicular to the optical axis O of the light source, so that the optical axis W of the wave plate is perpendicular to the optical axis O of the light source.

As shown in fig. 11B, a coordinate system is established with the optical axis W of the wave plate, and the P-polarized light has components Ex, ey along the optical axis W and a coordinate system formed in a direction perpendicular to the optical axis W, wherein Ex, ey can be expressed by using a light wave formula. P-light can be viewed as a spatial composite of two dimensional waves of the components Ex, ey.

When P light passes through the wave plate, the phase changes pi, namely 180 degrees, the phase constants of Ex and Ey have the change amount of pi, and for the light wave at a certain moment of the original polarization direction, b0, c0 and a0 are subjected to 180-degree phase change, and then the polarization positions are changed at the spatial positions after the light waves of two directional components are superposed to form b1, c1 and a1, so that the light in the S polarization direction is formed. The spatial position variations of b0, c0, a0 and b1, c1, a1 described above are merely examples.

After passing through the half-wave plate, the light originally in the P polarization direction becomes light in the S polarization direction, and the two polarization directions are perpendicular to each other as shown in fig. 11C.

Based on the above description, as shown in the schematic diagram of the optical path principle shown in fig. 12A, phase retarders with corresponding wavelengths are respectively arranged in the light outgoing paths of the blue laser assembly and the green laser assembly, and the phase retarders are specifically half-wave plates. In this example, the central wavelength of the blue laser is around 465nm, the central wavelength of the green laser is around 525nm, and when the optical path schematic diagram shown in fig. 12A is used, the half-wave plate 121 is located in the light-emitting path of the blue laser and is set corresponding to the central wavelength of the blue laser, and the half-wave plate 131 is located in the light-emitting path of the green laser and is set corresponding to the central wavelength of the green laser, so that the polarization directions of the green laser and the blue laser can be changed by 90 degrees, and the S light is changed into the P light.

Based on the optical path principle, in a specific implementation, the half-wave plate may be disposed in the inner cavity of the light source and located between the inner side of the light source housing and the light combining mirror corresponding to the laser assembly, and the half-wave plate is fixed by disposing a lens base on the bottom surface of the light source housing.

Alternatively, the half-wave plate may be disposed inside a window provided in the light source housing for the laser module, and fixed inside the window by gluing or fixing the bracket.

Alternatively, the half-wave plate may be disposed between the laser assembly and the outer side of the window of the light source housing, for example, the half-wave plate is attached or fixed to the outer side of the window, and the laser assembly (including the fixing bracket) is then mounted on the mounting position on the outer side of the window through the fixing bracket.

Alternatively, when the sealing glass is provided at the window glass, the half-wave plate may be located between the sealing glass and the light emitting face of the laser assembly. As shown in the exploded view of the laser module in fig. 5E-2, the front face of the light-transmitting window 10211 of the fixing bracket of the laser module further has a support platform (not shown), the half-wave plate 140 can be fixed on the support platform by gluing, and the support platform further has a receiving groove around it for receiving the first sealing member 1051. Fig. 5C-2 shows a schematic view of the half-wave plate installed on the front surface of the fixing bracket, wherein the half-wave plate 140 is installed at the position of the light-transmitting window 10211 of the fixing bracket and fixed by dispensing through the dispensing slots at the periphery. Wherein the length and width ranges of the half-wave plate 140 are respectively 25 to 30mm and 21 to 28mm; the length and width ranges of the light-transmitting window of the fixed support are respectively 20 to 24mm and 18 to 20mm, for example, in one embodiment, the half-wave plate is selected from 30mm by 28mm, and the size of the light-transmitting window is 24mm by 20mm.

After the half-wave plate 140 is fixed to the fixing bracket 104, the MCL type laser module mounted on the fixing bracket is mounted on the mounting position of the window 1021 of the light source housing 102 together with the fixing bracket 104, and as described above, the mounting position of the window 1021 of the light source housing is further provided with a second receiving groove for receiving a second sealing member 1052, and the sealing glass 105 is sandwiched by the first sealing member 1051 and the second sealing member 1052 on the laser module. Based on the above structure, after the light beam of the laser assembly is emitted from the light emitting chip, the light beam sequentially passes through the half-wave plate 140 and the sealing glass 105, and then enters the inner cavity of the light source from the window 1021 of the light source housing.

In the light source structure, the half-wave plates with corresponding colors are respectively arranged on the fixed supports of the blue laser component and the green laser component, so that the polarization polarity of the light beam changes by 90 degrees after passing through the corresponding half-wave plates. The green laser is already P light when incident to the first light combining mirror, the blue laser is also already P light when incident to the second light combining mirror, so that light beams output after the blue laser and the green laser are combined by the second light combining mirror are P light polarized light, which is the same as the polarization direction of the red laser, the third light combining mirror combines three-color light beams with the same polarization direction and outputs the light beams, and the light beams are homogenized, condensed and the like and enter an optical machine illumination light path, and are reflected by a DMD (digital micromirror device) and enter a lens, and the light beams are projected onto a screen by the lens to form an image.

As a modification of the above embodiment, in this case, the blue laser and the green laser are combined first and then combined with the red laser, and in this case, the half-wave plate may be disposed in the optical path after the blue laser and the green laser are combined and before the blue laser and the green laser are combined. Specifically, as shown in fig. 12B, another schematic diagram of the light source light path is provided, and a half-wave plate 141 may be disposed between the second light combining mirror 107 and the third light combining mirror 108, and transmit the combined light beam of the blue laser light and the green laser light emitted from the second light combining mirror 107. Based on the above optical path principle, the green laser and the blue laser output S-polarized light respectively, the green S light enters the first light combining mirror 106 and is reflected, the blue S light enters the second light combining mirror 107 and is transmitted, the second light combining mirror 107 also reflects the green S light, where the second light combining mirror 107 is a dichroic plate selected based on the wavelength rather than the polarization state, the second light combining mirror 107 combines the blue laser and the green laser, both of which are S light, and then passes through the half-wave plate 141, and the half-wave plate 141 changes the polarization direction of the green laser and the blue laser, and then enters the third light combining mirror 108.

Specifically, the half-wave plate 141 may be set for the wavelength of one of the colors, for example, for the wavelength of the green laser light, and the polarization direction of the green laser light is rotated by 90 degrees after passing through the half-wave plate, so that the original S light is changed into the P light. After the blue laser penetrates through the half-wave plate, because the wavelength of the half-wave plate is not set corresponding to the blue wavelength, the polarization direction of the blue laser is deflected by not 90 degrees, but is close to the P polarization direction, and because the visual function of human eyes to blue is low, the sensitivity to blue is low, and visual discomfort is more obvious when color cast occurs, such as red and green. Or, the half-wave plate 141 may also be set for the middle value of the blue and green central wavelengths, so that the polarization direction changes of the green laser and the blue laser are not 90 degrees but are both close to 90 degrees, and although the blue laser and the green laser are not converted from S light to P light, but are not in the original S light polarization state, the consistency of the whole system in the light processing process of the red, green, and blue three primary colors can be improved, the technical problem of uneven chroma such as "color spots", "color blocks" and the like appearing in a local area on the projection screen can be improved, and the principle is not described again.

In the above example, the half-wave plate 141 may be fixed by a fixing base provided on the bottom surface of the light source housing.

On the basis of the light source optical path schematic diagram shown in fig. 12B, an optical principle schematic diagram of a laser projection apparatus may be as shown in fig. 12D, and the working process thereof is referred to above and is not repeated. In the optical schematic diagram shown in fig. 12D, a half-wave plate 141 is provided in the light path of the combined blue laser beam and green laser beam, and the diffusion sheet 112 may be provided here or the diffusion sheet 112 may not be provided. Also, in the example of the present drawing, the arrangement relationship of the blue laser components and the green laser components is not limited.

It should be noted that the solution of disposing the half-wave plate shown in fig. 12B and 12D is also applicable to the optical path structure provided by the optical path schematic diagram shown in fig. 5g,5h, fig. 8A or fig. 8B. The working principle is the same as above and is not described in detail.

In the optical system, the transmittance of the same optical lens for P light and S light of different wavelengths is equivalent, and the reflectance for P light and S light is equivalent. The optical lens here includes various optical lenses in the entire laser projection apparatus, such as a condenser lens group, a lens group in an illumination optical path in an optical engine section, and a refractive lens group in a lens section. Therefore, when the light beam emitted from the laser light source passes through the whole projection optical system, the difference in transmission contrast is a result of superposition of the whole system, and is more obvious.

Before the half-wave plate is added, especially when the primary light is P light and S light polarized light, the selective transmission of the P light and the S light is obvious no matter whether the optical lens of the optical system or the projection screen is adopted. For example, the transmittance of the projection screen for P light (red light) is significantly higher than the transmittance for S light (green light and blue light) according to the incident angle of the projection light beam, which causes the problem of local color unevenness of the projection screen, i.e. the phenomenon of "color spot" or "color block" on the screen.

In the embodiments provided above, by disposing the half-wave plates in the light-emitting paths of the blue laser and the green laser, when the half-wave plates with corresponding wavelengths are respectively disposed for the blue laser and the green laser, the polarization directions of the blue laser and the green laser which can be targeted can be changed by 90 degrees, in this example, the polarization direction of S light is changed into the polarization direction of P light, which is consistent with the polarization direction of the red laser, so that, in the process of passing through the same set of optical imaging system and being reflected to the human eye through the projection screen, the transmittances of the blue laser and the green laser which are changed into the P polarized light in the optical lens are equivalent to the transmittance of the red laser which is the P light, the uniformity of the light processing process is close, the reflectance difference of the projection screen to the three-color laser is also reduced, the uniformity of the whole projection system to the light processing process of the three-color primary-color light is improved, the color cast phenomenon of "color spots" appearing in a local area on the projection screen can be fundamentally eliminated, and the display quality of the projection screen is improved.

And when a half-wave plate is arranged in the light path of the combined light of the blue laser and the green laser, the polarization direction of one of the green laser and the blue laser can be changed by 90 degrees, or the polarization directions of the lasers of two colors are not changed by 90 degrees but are close to 90 degrees. The polarization difference with the red laser P light can be reduced, and based on the principle, the consistency of the whole system in the light processing process of the red, green and blue three primary colors can be improved, and the technical problem of uneven chroma such as 'color spots' and 'color blocks' presented in local areas on a projection picture can be improved.

And, because the transmittance of the optical lens to P-polarized light is generally greater than that to S-polarized light in the optical system, and the reflectance of the projection screen applied in this example to P-polarized light is also greater than that to S-polarized light, by converting the blue laser and the green laser of S-polarized light into P-polarized light, so that the red, green and blue lasers are all P-polarized light, the light transmission efficiency of the projection beam in the whole system can also be improved, the brightness of the whole projection screen can be improved, and the projection screen quality can be improved.

As a solution to the technical problem of non-uniform chromaticity such as "color spots" and "color patches" appearing on the projection screen, the present embodiment provides a laser projection apparatus using a light source unit as shown in fig. 12C. In this example, a half-wave plate corresponding to the red wavelength is provided before the red laser beam is combined with the blue and green laser beams. For example, a half-wave plate 151, is disposed between the red laser assembly 110 and the third combiner 108.

The scheme for setting the half-wave plate can be referred to the scheme for setting the half-wave plate for the blue laser and the green laser respectively in the above embodiment.

For example, the half-wave plate may be disposed in the light source inner cavity, located in the light path between the inner side of the light source housing and the third light combining mirror, and fixed by disposing a lens base on the bottom surface of the light source housing.

Alternatively, the half-wave plate may be disposed inside a window provided in the light source housing for the red laser module, for example, fixed inside the window by gluing or fixing.

Alternatively, the half-wave plate may be disposed between the red laser device assembly and the outer side of the window of the light source housing, for example, the half-wave plate is attached or fixed to the outer side of the window, and the laser device assembly (including the fixing bracket) is then mounted on the mounting position on the outer side of the window through the fixing bracket.

Alternatively, when the sealing glass is provided at the window glass, the half-wave plate may be located between the sealing glass and the light emitting face of the laser assembly. The specific installation method can also be described with reference to fig. 5E-2, and is not described herein again.

The half-wave plate 151 is arranged corresponding to the wavelength of the red laser, and similarly, the polarization direction of the red laser can be rotated by 90 degrees by the half-wave plate, and the red laser is changed from P-polarized light to S-polarized light.

It should be noted that the scheme of setting a half-wave plate for the red laser is also applicable to the optical path schematic diagrams shown in fig. 5G, fig. 5H, fig. 8A, and fig. 8B of the present invention, and the principle thereof is not repeated again.

In the above example, by providing the half-wave plate in the output light path of the red laser, the red laser originally having P-polarized light is converted into S-polarized light, and the polarization directions of the red laser and the green laser are the same, so that the polarization directions of the three-color light of the system are the same, as described with reference to the principle of the foregoing embodiment, the transmittance of the projection optical system for the red laser, the blue laser, and the green laser, which are both S-polarized light, is reduced compared with the difference when the red laser, the blue laser, and the green laser are polarized light with different polarization directions, and the reflectance of the ultra-short focus projection screen for the three-color light, which is both S-polarized light, is also substantially the same, so that the light processing uniformity for each primary color is improved, and the phenomenon of uneven chroma such as "color spots", "color blocks", etc., presented on the projection screen can be eliminated or improved.

And, in the above embodiments, the light emitting surface of the laser is rectangular, correspondingly, the retarder is correspondingly disposed in the light output path of one color or two colors, and the shape is also rectangular, wherein the long side and the short side of the rectangular light emitting area of the laser are respectively parallel to the long side and the short side of the rectangular light receiving area of the retarder.

Since the laser beam contains high energy, the optical lens, such as a lens and a prism, will be subjected to temperature variation during the operation process, and the optical lens will form internal stress during the manufacturing process, and the internal stress will be released along with the temperature variation, and will form stress birefringence, which will cause different phase retardations for the beams with different wavelengths, which can be regarded as secondary phase retardation. Therefore, in the actual optical path, the phase change of the light beam is based on the effect of the half-wave plate and the stress birefringence of the optical lens, and the retardation inherently caused by the optical lens is different according to the system design. When the technical solutions of the embodiments in the present application are applied, the secondary phase retardation caused by an actual system may preferably be corrected to approach or reach a theoretical value of 90 degrees change of the polarization direction of the light beam.

The half-wave plate has an optical axis in the plane of its slab, as shown in fig. 11A, the optical axis W of the half-wave plate is in a spatially perpendicular relationship with the system optical axis O, and the optical axis of the half-wave plate is parallel to the long or short side of the half-wave plate. In the specific application of the above embodiment, as shown in fig. 11D, the half-wave plate is set as: the half-wave plate is rotated by a preset angle, such as C degrees, along the long side or short side of the rectangular half-wave plate, as shown by the dotted line. Through the deflection of the angle, the optical axis of the half-wave plate is deflected by about plus or minus C degrees, so that the phase of the light beam is changed to about 180 +/-2C degrees, and then the light beam is superposed with the secondary phase delay of the optical lens of the system, and finally the polarization direction of the light beam is changed to about 90 degrees and is close to the theoretical design value. In many of the embodiments described above in this application, C may take the value 10.

In one or more embodiments, for the tricolor light with different polarization directions of the laser projection light source, the half-wave plate is arranged in the light output path of one color or two colors in the laser projection device light source, the polarization direction of the light with one color or two colors which correspondingly penetrates is changed to be consistent with the polarization direction of the light with other colors, and the polarization polarity of the tricolor light which is output by the laser projection device is the same, so that when the laser beams which are emitted by the laser projection device light source pass through the same optical imaging system and are reflected into human eyes through the projection screen, the transmittance of the optical system to the tricolor laser is close, the difference of the reflectivity of the projection screen to the tricolor laser is reduced, the consistency of the whole projection system to the light processing process of the tricolor color light is improved, the phenomenon of uneven chromaticity such as color spots and color blocks which are presented in a local area on a projection picture can be fundamentally eliminated, and the display quality of the projection picture is improved.

It can be understood by those skilled in the art that, when the foregoing embodiments solve the problem of displaying a projection image due to different polarization directions of three primary colors of light and obvious difference of transmittance of a projection screen for light with different polarization directions, red laser light is taken as P light, and blue and green laser light is taken as S light for illustration, and the embodiments are not limited to this combination of P light and S light, and those skilled in the art can make adaptive changes according to the color and polarization direction of an actual light beam and in combination with the core principle embodied in the embodiments of the present application, and the above changes should also be within the scope of the present application.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser projection device is characterized by comprising a whole shell, a three-color laser light source, an optical machine and a lens; the optical machine and the lens are connected and arranged along a first direction of the whole machine shell; the light source and the radiating fins are arranged in a space enclosed by the optical machine, the lens and part of the whole machine shell along the first direction, a plurality of circuit boards and a second fan are also arranged in a space enclosed by the optical machine, the lens and the other part of the whole machine shell, and the second fan is arranged close to the inner side of the whole machine shell;

along the direction vertical to the first direction, a cold row and a first fan are arranged between one side of the radiating fin and part of the whole machine shell, and the other side of the radiating fin is provided with the lens; the first fan blows airflow to the lens from the cold row and the radiating fins in sequence, the airflow flows through the circuit boards, and the airflow is exhausted out of the whole machine shell through the second fan.

2. The laser projection device of claim 1, wherein a light valve of the optical engine is provided with a heat sink, and a fourth fan is provided at the heat sink to blow air flow from the heat sink to the plurality of circuit boards and to exhaust the second fan out of the integral housing.

3. The laser projection device of claim 1, wherein one side of the light source is connected to the heat dissipation fin by a heat pipe; the light source is provided with a first light outlet, the first light outlet is connected with the optical machine, the other side face of the light source opposite to the first light outlet is connected with a cold head, and the cold head is communicated with the cold row through a pipeline.

4. The laser projection device as claimed in claim 1 or 3, wherein a third fan is further disposed between the other side of the heat sink and the lens, and the third fan blows an air flow in a direction from the heat sink to the lens.

5. The laser projection device of claim 1, wherein the number of the second fans is at least 2, and the second fans are arranged in parallel along the inner side of the whole device shell.

6. The laser projection device of claim 3, wherein the light source includes a light source housing, a red laser assembly mounted on the light source housing being connected to the cold head; a blue laser component and a green laser component are respectively arranged on the side surface of the light source shell opposite to the radiating fin; the blue laser assembly and the green laser assembly are connected with the heat pipe and conduct heat to the heat dissipation fins.

7. The laser projection device of claim 6, wherein the heat sink on the back of the red laser assembly is in contact with the cold head through a first heat conducting block, wherein the area of the first heat conducting block is larger than the area of the cold head contact surface.

8. The laser projection device of claim 7, wherein the temperature of the cold head is greater than the temperature of the cold row by a difference of 1-2 ℃.

9. The laser projection device of claim 6, wherein the blue laser assembly and the green laser assembly are coupled to a plurality of heat pipes via a heat conducting block and to the heat sink fins via heat pipes.

10. The laser projection device as claimed in claim 9, wherein the heat pipe is a plurality of straight heat pipes, and the heat dissipation fin has a plurality of channels therein for accommodating the heat pipes.

11. A laser projection device as claimed in any one of claims 6 to 10, wherein the laser projection device satisfies at least one of:

the working temperature of the red laser component is less than 45 ℃;

the operating temperature of the blue laser assembly and the green laser assembly is less than 65 ℃.

12. The laser projection device of any one of claims 1 to 10, wherein the first fan is disposed between the cold row and the whole machine housing, or the first fan is disposed between the cold row and the heat dissipation fins.

13. The laser projection apparatus according to any one of claims 6 to 10, wherein the emission power of the red laser package is 24W to 56W, the emission power of the blue laser package is 48W to 115W, and the emission power of the green laser package is 12W to 28W.