CN112114484B

CN112114484B - Laser projection device

Info

Publication number: CN112114484B
Application number: CN201910538771.9A
Authority: CN
Inventors: 颜珂; 田有良
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2019-06-20
Filing date: 2019-06-20
Publication date: 2023-04-07
Anticipated expiration: 2039-06-20
Also published as: CN112114484A; WO2020253165A1; CN116774509A

Abstract

The invention provides laser projection equipment, which comprises a whole machine shell and a light source, wherein the whole machine shell is provided with a light source; the light source comprises a red laser component, a green laser component and a blue laser component, wherein the red laser component and the green laser component are arranged in parallel, and the blue laser component is vertical to the red laser component and the green laser component; and a first light combining mirror is arranged at the intersection of the blue laser and the green laser, the first light combining mirror transmits the blue laser and reflects the green laser, a second light combining mirror is arranged at the intersection of the blue laser, the green laser and the red laser after light combination, the second light combining mirror transmits the red laser and reflects the blue laser and the green laser to a third light combining mirror, and the third light combining mirror reflects the red laser, the blue laser and the green laser to a light source light outlet. The laser projection equipment has small light loss of red laser, is beneficial to maintaining the power ratio or the color ratio of three-color laser beams, and can present a projection picture with high brightness and good color.

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 a mercury lamp, and the laser also has advantages of a small etendue and high luminance as compared with 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. As shown in fig. 17, because of different light emitting mechanisms, a red laser light emitting chip has two light emitting points, but one light emitting chip corresponds to one collimating lens, and therefore, an effect of collimating the two light emitting points by one collimating lens is inferior to an effect of collimating one light emitting point by one collimating lens, which makes an angle of divergence of the red laser light after being emitted from a light emitting surface of the laser assembly larger than that of the other two color laser lights, but in practical applications, an optical path system is common to the three color laser lights, and in a light beam transmission process, an optical lens generally has a light receiving range of itself or has a high light processing efficiency in a certain angle range, and for the red laser light, because the divergence degree is fast, a light beam in a large angle range is easily lost, so that the light loss of the red laser light is generally large, and the loss rate is difficult to estimate, and is difficult to solve by using a power compensation method.

A solution is needed to solve the problems of unbalanced system color ratio and poor quality of the projected image caused by large red laser light loss in the three-color laser application.

Disclosure of Invention

The invention provides a laser projection device, which comprises a three-color laser light source and can present a projection picture with high brightness and good color.

The invention provides a laser projection device: the whole machine comprises a shell and a light source; the light source comprises a red laser component, a green laser component and a blue laser component, wherein the red laser component and the green laser component are arranged in parallel, and the blue laser component is vertical to the red laser component and the green laser component; a first light combining mirror is arranged at the intersection of the blue laser and the green laser, the first light combining mirror transmits the blue laser and reflects the green laser,

and a second light combining mirror is arranged at the junction of the blue laser, the green laser and the red laser after light combination, the second light combining mirror transmits the red laser and reflects the blue laser and the green laser to a third light combining mirror,

the third light combining mirror reflects the red laser, the blue laser and the green laser to a light source light outlet;

furthermore, the light reflectivity of the first light combining mirror and the light reflectivity of the second light combining mirror are all larger than the light transmissivity of the first light combining mirror and the second light combining mirror;

furthermore, the light emitting power of the green laser assembly is smaller than that of the red laser assembly and that of the blue laser assembly;

further, the light spot sizes of the red laser reaching the second light combining mirror are larger than those of the blue laser and the green laser;

furthermore, a homogenizing element and a converging lens group are sequentially arranged in a light path from the third light combining mirror to the light outlet of the light source;

furthermore, a diffusion sheet is arranged in a light path from the first light combining mirror to the second light combining mirror and is used for diffusing and transmitting the green laser and the blue laser;

further, the homogenizing element is a diffusion sheet with regularly arranged microstructures, or the homogenizing element is a two-dimensional diffraction element;

further, the three-color light source beam is emitted from the light source light outlet and then enters the light receiving component through the diffusion wheel;

further, a half-wave plate is arranged in a light path from the first light combining mirror to the second light combining mirror;

the half-wave plate is arranged corresponding to the wavelength of the green laser, or the half-wave plate is arranged corresponding to the wavelength between the green laser and the blue laser.

Further, half-wave plates are respectively arranged in light paths from the light emitting surfaces of the blue laser assembly and the green laser assembly to the first light combining mirror, and the half-wave plates are respectively correspondingly arranged corresponding to the wavelength of blue laser and the wavelength of green laser;

further, the polarization directions of the blue laser and the green laser are the same, and the polarization directions of the red laser and the two color lasers are different;

furthermore, the light emitting power of the red laser assembly ranges from 24W to 56W, the light emitting power of the blue laser assembly ranges from 48W to 115W, and the light emitting power of the green laser assembly ranges from 12W to 28W.

The laser projection device of one or more embodiments uses a three-color laser light source, wherein a red laser is output from a light outlet of the light source after being transmitted and reflected once, a blue laser is output from the light outlet after being transmitted and reflected once and a green laser is output from the light outlet after being reflected three times, the light path of the red laser is shortest, and the total number of times of the transmitted and reflected lights is also smallest, so that the light loss in the light path transmission is smaller, the power ratio or the color ratio of the three-color laser light beam is favorably maintained, and the laser projection device can present a projection picture with high brightness and good color.

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. 1 is a schematic diagram of a whole structure of a laser projection apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an optical principle of a light source according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an optical principle of another light source according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a light source structure according to an embodiment of the invention;

FIG. 5 is a diagram of an ultra-short-focus projection screen according to an embodiment of the present invention;

FIG. 6 is a graph of the change in reflectivity of the projection screen of FIG. 5 to the projection beam;

FIG. 7 is a schematic view of a laser assembly according to an embodiment of the present invention;

FIG. 8 is a schematic front view of a laser assembly according to an embodiment of the present invention;

FIG. 9 is an exploded view of a laser assembly according to one embodiment of the present invention;

FIG. 10 is an exploded view of another laser assembly in accordance with an embodiment of the invention;

FIG. 11 is an exploded view of another laser assembly in accordance with an embodiment of the present invention;

FIG. 12 is a schematic diagram of an MCL laser;

FIG. 13 is a schematic diagram of a laser circuit package of FIG. 12;

FIG. 14 is a schematic view of a heat dissipation system for a red laser module according to an embodiment of the present invention;

FIG. 15 is a schematic view of a heat dissipation system for blue or green laser modules according to an embodiment of the present invention;

FIG. 16 is an exploded view of a heat dissipation system for blue or green laser modules according to an embodiment of the present invention;

FIG. 17 is a schematic diagram of a red laser chip;

FIG. 18 is a schematic diagram illustrating an optical path principle of a laser projection system according to an embodiment of the present invention;

FIG. 19 is a schematic diagram of an optical path of another laser projection system according to an embodiment of the present invention;

FIG. 20 is a schematic view of a diffuser structure according to an embodiment of the present invention;

FIG. 21 is a schematic diagram showing the energy distribution of the laser beam after passing through the diffuser shown in FIG. 20 according to one embodiment of the present invention;

FIG. 22 is a schematic diagram of a light spot in the light path according to an embodiment of the present invention;

FIG. 23 is a schematic view of an optical axis of a wave plate;

FIG. 24 is a schematic diagram of a 90 degree change in linearly polarized light;

FIG. 25 is a schematic view of P and S light polarization directions;

FIG. 26 is a schematic view of a wave plate rotation arrangement;

FIG. 27 is a schematic diagram of a laser projection optical path according to an embodiment of the present invention;

FIG. 28 is a schematic diagram of another laser projection optical path according to an embodiment of the present invention;

FIG. 29 is a schematic diagram of a laser projection optical path according to another embodiment of the present invention;

description of reference numerals:

10-laser projection device, 101-housing;

100-light source, 102-light source housing, 1021-window, 104-fixed support, 1041-light transmissive window, 1042-third seal; 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-blue laser assembly, 111-converging mirror set, 112-diffusing plate, 120-green laser assembly, 130-red laser assembly, 121, 131, 141, 151, 140-half-wave plate;

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

200-optical machine, 250-light-receiving component, 260-diffusion wheel;

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

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 obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection 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. 1.

Fig. 1 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 engine 200, and a lens 300 according to optical functional portions, where the optical portions have corresponding casings for packaging and achieve a certain sealing or airtight requirement, for example, the light source 100 is hermetically sealed, so as to 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 machine housing 102, as shown in fig. 1, the first direction may be a width direction of the whole machine, 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.

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 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.

The light source comprises a light source shell, and a blue laser component, a green laser component and a red laser component which are arranged on different sides of the light source shell and respectively emit blue laser, green laser and red laser. The green laser component and the red laser component are arranged on the same side face in parallel and are vertical to the blue laser component in spatial position, namely, the side face of the light source shell where the green laser component and the red laser component are located is vertical to the side face of the light source shell where the blue laser component is located, and the two side faces are vertical to the bottom face of the light source shell or the bottom face of the whole shell.

Referring to fig. 2, a schematic diagram of a principle of an optical path of the light source 100 is shown, where a light beam emitted by the red laser component is emitted from the light source light outlet after being transmitted and reflected once, a light beam emitted by the green laser component is emitted from the light source light outlet after being reflected three times, and a light beam emitted by the blue laser component is emitted from the light source light outlet after being transmitted once and reflected twice. Therefore, in the schematic diagram of the optical path principle, the optical path through which the red laser passes is shortest, and the number of times of reflection through which the red laser passes is the smallest.

The three-color laser components all output rectangular light spots, and are vertically installed on the side face of the light source housing 102 along the long side direction of each rectangular light spot. 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. 4, 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. 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.

And an air pressure balancing device is also arranged on the bottom surface or the top cover of the light source shell). The air pressure balancing device can be a filter valve and can be used for communicating the inside of the light source with the outside, exchange of air flows is achieved, when the temperature of the inside of the light source rises, the inside air flows outwards, after the temperature is recovered and cooled, the outside air flows can also enter the inside of the light source, and as the filter valve can be arranged into an airtight waterproof filtering membrane, the filter valve can filter particle dust and the like in a certain diameter range outside, and the filter valve stops outside and keeps the cleanliness of 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 rises too high, the air pressure of the cavity in the light source can be balanced by communicating the pressure relief device to the outside or increasing the volume of the sealed space of the cavity in the light source by forming the air containing structure, and the working reliability of each optical device in the cavity in the light source is improved.

Since the assembly structure of the three-color laser module and the light source housing is substantially the same, for the sake of convenience of describing the connection relationship between the laser module and the light source housing, the assembly structure of any one of the color laser modules will be described 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. 12 and fig. 13, 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 group 1101 includes a plurality of collimating lenses, which generally correspond to the light emitting positions of the light emitting chips one by one, and perform corresponding collimation on the laser beams.

As shown in fig. 13, the MCL-type laser assembly further includes

PCB boards

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

PCB boards

1104a and 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. 7 and 8 are an assembly structure diagram and an exploded structure diagram of the laser component and the fixing bracket of any color, respectively.

As shown in fig. 4, 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 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 fixed support through a screw, and particularly, the metal substrate of the MCL laser is provided with an assembling hole which can be locked with the fixed support.

As shown in fig. 9, the fixing bracket 104 is a sheet metal part having a light-transmitting window 1041, 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 component of any color is installed on the installation position of the back surface of the light-transmitting window 1041 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 surface of the light-transmitting window 1041 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 surface of the MCL-shaped laser device to fix the MCL-shaped laser device to the mounting position. The third sealing member 1042 can also play a role of buffering, so as to 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, which are driven into the studs around the window by screws through the studs of the mounting bracket.

Because the inside optical lenses that is provided with of light source 100 is accurate part, and the energy density among the light beam transmission process is very high, if the internal environment cleanliness factor is not high, dust granule can be accumulated on accurate lens surface, causes the light treatment efficiency to descend, and then causes the light decay of light path, and whole laser projection equipment's complete machine luminance also can descend thereupon. In this example, the light source is internally protected from dust to reduce the light attenuation problem, and specifically, as shown in fig. 10, 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 cannot 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. 10, for the convenience of the above-described sealing glass mounting, in this example, the sealing glass 105 is mounted on the side of the window 1021 near the laser module. The fixing bracket 104 further has a first receiving groove at the front side for receiving the first sealing member 1051, and a second receiving groove at the window 1021 of the light source housing for receiving the second sealing member 1052. The sealing glass 105 is located between the first sealing 1051 and the second sealing 1052, specifically, the second sealing 1052 is placed in the second receiving groove at the window 1021, a matching fixing groove with the sealing glass 105 is arranged in the second sealing 1052, the sealing glass 105 is placed in the fixing groove, the first sealing 1051 is installed in the first receiving groove of the fixing support light transmission window 1041 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 shell, the first sealing 1051 is in pressing contact with the sealing glass 105, and the sealing glass 105 is clamped between the first sealing 1051 and the second sealing 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 the laser projection apparatus provided in this embodiment, as shown in the schematic diagram of the light source light path principle shown in fig. 2, a first light combining mirror 106 is disposed at an intersection of the blue laser and the green laser, the first light combining mirror transmits the blue laser and reflects the green laser, and a second light combining mirror is disposed at an intersection of the blue laser, the green laser and the red laser after light combining, the second light combining mirror reflects the red laser and transmits the blue laser and the green laser to a third light combining mirror, and the third light combining mirror reflects and outputs the three-color laser to the light source light outlet.

Specifically, the optical axis direction of the light beam on the light emitting surface of the blue laser component 110 is parallel to the optical axis of the light source light outlet, but the direction is opposite. The green laser light emitted by the green laser assembly 120 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 110 is transmitted through the first light combining mirror 106, and the blue laser light and the green laser light can be combined and output through the first light combining mirror 107.

The output direction of the blue laser and the green laser combined and output by the first light combining mirror 106 is perpendicular to the output direction of the red laser emitted by the red laser assembly 130, and has a junction, a second light combining mirror 107 is arranged at the junction of the three light beams, and the second light combining mirror 107 reflects the red laser and transmits the green laser and the blue laser. The three-color laser beams are combined to form a light beam, which enters the homogenizing element 109, and is emitted from the light source light outlet after the light spot is reduced by the converging lens group 111.

In the light source configuration shown in fig. 4, the green laser assembly 120 and the red laser assembly 130 are mounted side-by-side on one side of the light source housing and the blue 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.

The inner cavity of the light source is also provided with a plurality of light-combining lenses and a converging lens group. Specifically, the first light combining mirror is positioned between the blue laser assembly and the green laser assembly at the intersection of the blue laser assembly and the green laser assembly. The second light combining mirror is obliquely arranged towards the light emitting surface of the red laser component, transmits the red laser and reflects the blue laser and the green laser. The first light combining mirror and the second light combining mirror are arranged approximately in parallel and are arranged at an angle of 45 degrees with the light emitting surface of the corresponding laser component. The first light combining lens and the second light combining lens are fixedly clamped on the bottom surface of the light source shell through the base, and the angles of the first light combining lens and the second light combining lens can be finely adjusted within plus and minus 3 degrees in consideration of assembly tolerance. The light-emitting surface of the third light-combining mirror is perpendicular to the light-emitting surface of the second light-combining mirror, and is arranged at an angle of 45 degrees with the optical axis of the reflected three-color laser beam.

The second light combining mirror transmits the red laser, reflects the blue laser and the green laser, and then outputs the three-color laser beams to the third light combining mirror, and the third light combining mirror reflects the red laser, the blue laser and the green laser to the light source light outlet.

The third light combining lens is arranged close to the converging lens group and outputs the three-color laser light combination to the converging lens group.

The third light combining mirror is a reflector, and the first light combining mirror and the second light combining mirror are dichroic films.

And the light reflectivity of the first light combining mirror and the second light combining mirror is greater 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. 12, 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. 17, 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 optical path shown in fig. 2, the blue laser light is output along the light emitting surface of the blue laser assembly, and then is transmitted once, reflected twice, and exits from the light source light outlet after passing through the homogenizing element 109 and the condensing lens group 111. For green laser, after three reflections, the green laser enters the homogenizing element 109 and the converging lens group 111 and exits from the light source exit. The red laser beam enters the homogenizing element 109 and the converging lens group 111 after primary transmission and primary reflection, and exits from the light source exit. It can be seen that the light 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 light source light outlet, so that the light loss generated by the red laser light during the light path transmission can be reduced. And when the influence of the optical path on the optical loss is not considered, the light energy of the red laser after the transmission of the red laser through the second light combining mirror and the reflection of the third light combining mirror can reach about 99% by 97% =96%, and it should be noted that, here, the calculation of the light energy efficiency of the red laser does not consider the influence of the transmittance and the reflectance of the optical lens only when the divergence angle of the red laser is large and the large-angle light loss exists.

And the blue laser is transmitted once and reflected twice, when only the influence of the transmittance on the optical loss is considered, the blue laser is transmitted from the first light combining mirror, the light energy output after the reflection of the second light combining mirror and the third light combining mirror can reach about 97%. About.99%. About.95%, and the light energy output from the third light combining mirror can reach about 99%. About.99%. About.97% after the reflection of the green laser is reflected for three times. In practical applications, the blue laser may have a higher luminous power and the visual function of the human eye for blue is relatively low. The transmittance and reflectance loss of the red laser passing through the lens is less than that of the green laser, the optical path of the red laser is shortest, the divergence angle of the red laser in the transmission optical path is largest, and the red laser is easy to lose when the optical transmission path is overlong. And thus can be considered as having comparable losses for the red and green lasers. 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, so that 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.

Above-mentioned laser instrument is arranged and is squarely, and laser instrument subassembly and optical lens piece are compacter and regular, do benefit to structural design, can reserve out regular space for the casing, for example be convenient for set up the heat dissipation device.

The MCL type laser assembly is adopted by the laser assembly, compared with the traditional BANK type laser assembly, the MCL type laser assembly is obviously smaller in size, therefore, in the embodiment, the structural size is obviously reduced compared with the traditional BANK type laser assembly, more space can be reserved nearby a light source, convenience is provided for heat dissipation design, for example, a heat radiator is provided, the fan can be placed more flexibly on position selection, and structures such as a circuit board can be arranged, the length of the whole machine structure in a certain direction can be reduced, or the size of the whole machine can be reduced.

As a variation of fig. 2, different from the optical path shown in fig. 2, the positions of the red laser component and the green laser component may also be exchanged, for example, as shown in fig. 3, the red laser emitted from the red laser component 130 is reflected by the first combining mirror 106, and then sequentially passes through the second combining mirror 107 and the third combining mirror 109, so that the optical energy loss of the red laser component is 1-99% + 99% =3%, and the loss is reduced compared with the optical path shown in fig. 2, but the optical path is slightly increased by a distance, according to the above-mentioned transmittance and reflectance calculation. The optical energy loss of the green laser is 1-97% by 99% =4%, but the optical path length of the green laser is shortened. Overall, the light loss of the red laser light and the green laser light is comparable.

In the embodiments, the light path of the red laser is set to be shortest, so that the transmission or reflection times of the red laser are reduced, the light transmission light loss of the red laser can be reduced, the light loss of the red laser before beam combination can be reduced as much as possible, the proportion of the beam power and the color of the three-color light source can be maintained, the white balance of the system is close to a theoretical set value, and the high quality of a projection picture is realized.

Referring to fig. 2 and 3, in the light source of the above-mentioned embodiment of the laser projection apparatus, after the three-color laser 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. 2, the light source 100 further includes a homogenizing element 109 and a focusing 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. 20. The microstructures of the conventional diffusion sheet are random and irregular, the microstructures regularly arranged by the homogenization diffusion sheet used in the light source framework can change the energy distribution of a laser beam from a Gaussian shape to a shape shown in figure 21 similar to the principle that a fly-eye lens homogenizes the laser beam, as shown in figure 21, the energy near the central optical axis of the laser is greatly weakened and smoothed, and the divergence angle of the laser beam is increased, so that the effect of homogenizing the energy is greatly superior to that of the conventional diffusion sheet with the irregularly arranged microstructures.

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, which are both spherical lenses, although both spherical lenses may be aspheric lenses, which is easier to form and control precision than aspheric lenses, and the cost of the spherical lenses may 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.

In one embodiment, the converging lens group is located at the light source light outlet of the light source housing, specifically, the rear lens or the entire lens group in the converging lens group can be mounted at the light source light outlet, and the housing around the converging lens group and the light source light outlet is 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, so that the shortening of the light path is facilitated, and the volume of the light source shell is reduced.

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 in fig. 18, in this 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 collection mirror 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 has the maximum relationship, and the divergence angle of the blue laser subarea has the minimum relationship. 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. 22. 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. The three-color light combination exists at present, and the speed of the divergence angle of the three-color light combination is increased to be higher than that of the laser of another color along with the increase of the transmission distance of the light path, so that the spot size of the red laser is always larger although the three-color light combination is homogenized, condensed and possibly diffused and homogenized again through a rotating diffusion sheet. The test spot at the light incident surface of the light pipe also exhibits this 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 diagram provided in the foregoing fig. 2, as shown in fig. 19, 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 first light-combining mirror 106 and the second light-combining mirror 107. 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 quality of light beams 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, the red laser component and the blue laser component are adopted, and the polarization direction of the green laser component is 90 degrees, wherein the red laser is P light, and the blue and green lasers 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 color and contrast, the laser projection apparatus is usually combined with a projection screen with higher gain and contrast, such as an optical screen, to better reduce the projection picture with high brightness and high contrast.

An ultra-short-focus projection screen is shown in fig. 5, which is a fresnel optical screen. The Fresnel lens 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 phenomenon is that in the currently used three-color laser, the polarization directions of the laser beams of different colors are different, and multiple optical lenses, such as lenses and prisms, are usually disposed in the optical system, and the transmittance of the optical lenses themselves for P-polarized light and S-polarized light is different, such as the transmittance of the optical lenses for P light is relatively greater than that for S light, while, due to the structure of the screen material, the ultra-short-focus projection screen itself will exhibit significant changes in transmittance and reflectance for beams of different polarization directions with the change of the incident angle of the ultra-short-focus projection beam, as shown in fig. 6, for the red projection beam, when the projection angle is about 60 degrees, tests show that the reflectance of the projection screen for the P-type red projection beam and the reflectance for the S-type red projection beam differ by more than 10%, that is the reflectance for the ultra-short-focus projection screen for P light is greater than that for S light, so that the P light reflected by the screen enters the human eye, and the S-type red projection beam reflected by the screen relatively decreases, and the reflectance for the P-type red projection beam of the projection screen for the S-light enters the human eye, and the same polarization direction, and the three-color projection screen is also significantly unbalanced, and the final projection screen is an unbalanced image with different polarization of the same, and this phenomenon occurs.

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. 23, 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. 24, 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 an optical 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. 25.

Based on the above description, as shown in the schematic diagram of the optical path principle shown in fig. 27, phase retarders, specifically half-wave plates, with corresponding wavelengths are respectively disposed in the light outgoing paths of the blue laser module and the green laser module. In this example, the central wavelength of the blue laser light is about 465nm, the central wavelength of the green laser light is about 525nm, and when the optical path schematic diagram shown in fig. 27 is used, the half-wave plate 121 is located in the light-emitting path of the blue laser light and is set corresponding to the central wavelength of the blue laser light, and the half-wave plate 131 is located in the light-emitting path of the green laser light and is set corresponding to the central wavelength of the green laser light, so that the polarization directions of the green laser light and the blue laser light 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, where a 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. 11, a support platform (not shown) is further provided on the front surface of the light-transmitting window 1041 of the fixing bracket of the laser module, the half-wave plate 140 can be fixed on the support platform by gluing, and a receiving groove is further provided around the support platform for receiving the first sealing member 1051. Fig. 9 shows a schematic diagram 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 transmission window 1041 of the fixing bracket and fixed by dispensing through the dispensing slots on 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 after being transmitted by the sealing glass 105, the light beam enters the inner cavity of the light source from the window 1021 of the light source shell.

In the light source structure, the half-wave plates with corresponding colors are respectively arranged on the fixed supports of the blue laser assembly and the green laser assembly, 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 inciding into first beam combiner, blue laser is also already P light when inciding into first beam combiner, thereby the light beam of output after blue laser and green laser beam combination through first beam combiner is P light polarization light, this is the same with the polarization direction of red laser, the second beam combiner is the three-colour light beam that the polarization direction is unanimous and is synthesized light output, through homogenizing, beam contraction etc. processing, get into ray apparatus illumination light path, get into the camera lens through DMD reflection, project the formation of image on the screen by the camera lens, because the three-colour polarization direction is unanimous, the phenomenon that the chromaticity is inhomogeneous such as "color spot", "color lump" of projection picture can be eliminated or alleviated greatly.

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. 28, which provides another principle diagram of light source light path, a half-wave plate 141 may be disposed between the first light combining mirror 106 and the second light combining mirror 107, and transmit the combined light beam of the blue laser light and the green laser light emitted from the first light combining mirror 106. 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 first light combining mirror 106 and is transmitted, the first light combining mirror 106 combines the blue laser and the green laser, both of which are S light, and then the combined light 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 second light combining mirror 107.

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 as to change the original S light 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.

It should be noted that the solution of disposing the half-wave plate shown in fig. 28 is also applicable to the optical path architecture provided by the optical path schematic shown in fig. 2, fig. 3, fig. 18 or fig. 19. 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, with the difference of the incident angles of the projection light beams, the transmittance of the projection screen for P light (red light) is significantly greater than the transmittance for S light (green light and blue light), which causes the problem of local non-uniform chromaticity of the projection screen, i.e. the phenomenon of "color spots" and "color blocks" 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. 29. 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 second beam combiner 107.

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, and fixed inside the window by gluing or fixing the bracket.

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

Alternatively, where a 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. 11, 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. 2, fig. 18, and fig. 19 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 generate internal stress during the manufacturing process, and the internal stress will be released with the temperature variation, and will generate stress birefringence, and the stress birefringence 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 its optical axis in the plane of its slab, as shown in fig. 23, in a spatially perpendicular relationship with the system optical axis O, the optical axis W of the half-wave plate being parallel to the long or short side of the half-wave plate. In the specific application of the above embodiment, as shown in fig. 26, 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 direction of the rectangular half-wave plate, as shown by the dotted line in the figure. Through the deflection of the angle, the optical axis of the half-wave plate is deflected by about positive and negative 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 a 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.

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 few tenths of an inch, but it needs 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 and the like are driven by electric signals, certain heat is generated, and each electronic device also has a set working temperature. Therefore, good heat dissipation and temperature control are very important guarantees for proper operation of the laser projection device.

Specifically, as shown in fig. 15 and fig. 16, the heat conducting block 603 is in contact with the heat sink of the green or blue laser assembly for heat conduction, the outer surface of the heat pipe 602 is in contact with the heat conducting block for 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 fin 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.

And, as shown in fig. 14, the red laser assembly is connected to a cold head 610, and heat is dissipated by liquid cooling. 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 pump is further included and used for driving 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 reduction of the size of 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.

The space enclosed by the optical machine, the lens and the other part of the whole machine shell is also internally provided with a plurality of circuit boards 500 and a plurality of second fans, the second fans are arranged close to the whole machine shell, and the number of the second fans can be a plurality.

In a laser projection device, the light source 100 is a laser light source, and includes laser components of different colors having 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.

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 ℃, air cooling and heat dissipation are performed on 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 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 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 enhance the heat transfer coefficient.

In the laser projection apparatus provided in the above embodiment, the emission power of the red laser module may range from 24w to 56w, the emission power of the blue laser module may range from 48w to 115w, and the emission power of the green laser module may range from 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 a 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 and green laser assemblies, 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 severe. 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. The liquid cooling heat dissipation method has a higher component cost than 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. 14, 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 rapidly concentrated and transferred to the cold head, and the heat conduction efficiency is improved.

In the heat dissipation system configuration shown in fig. 14, 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 row 611 and the pipeline, a liquid replenisher 612 is further provided, as mentioned above, the liquid replenisher 612 is used for replenishing cooling liquid for the circulation of the system, so that the liquid replenisher can be provided at multiple positions of the whole circulation system, and according to factors such as system structural space, the liquid replenisher can be one or more, can be connected with a pump, and can also be provided close to the cold row.

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. 15 and 6C, the heat sink on the back of the blue laser assembly 120 and the heat sink on the back of the green laser assembly 130 are 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, can also be a whole structure, are convenient to install like this, and the laser assembly heat dissipation demand of two kinds of colours is the same, also are convenient for control temperature.

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 cavity of the light source to combine and homogenize the laser beams in different directions.

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 machine shell and a light source, wherein the light source is arranged on one side of the whole machine shell;

the light source comprises a red laser component, a green laser component and a blue laser component, wherein the red laser component and the green laser component are arranged in parallel, and the blue laser component is vertical to the red laser component and the green laser component;

a first light combining mirror is arranged at the intersection of the blue laser and the green laser, the first light combining mirror transmits the blue laser and reflects the green laser,

a second light combining mirror is arranged at the intersection of the blue laser, the green laser and the red laser after light combination, the second light combining mirror transmits the red laser and reflects the blue laser and the green laser to a third light combining mirror, wherein the polarization directions of the blue laser and the green laser are the same, the polarization directions of the red laser and the two colors of laser are different, a half-wave plate is further arranged in a light path before the blue laser, the green laser and the red laser enter the second light combining mirror, and the polarization directions of three colors of laser beams output by the second light combining mirror are the same;

and the third light combining mirror reflects the red laser, the blue laser and the green laser to a light source light outlet.

2. The laser projection device of claim 1, wherein the first and second light-combining mirrors each have a light reflectivity greater than a light transmissivity thereof.

3. The laser projection device of claim 1, wherein the green laser assembly has a luminous power that is less than the luminous power of each of the red and blue laser assemblies.

4. The laser projection apparatus of claim 2 or 3, wherein the spot size of the red laser light reaching the second light combining mirror is larger than the spot size of the blue laser light and the spot size of the green laser light.

5. The laser projection apparatus of claim 1, wherein a homogenizing element and a converging lens group are further disposed in sequence in the light path from the third light combining mirror to the light outlet of the light source.

6. The laser projection device as claimed in claim 2 or 3, wherein a diffusion sheet is further disposed in a light path from the first light combining mirror to the second light combining mirror, for diffusing and transmitting the green laser light and the blue laser light.

7. The laser projection apparatus of claim 5, wherein the homogenizing element is a diffuser having regularly arranged microstructures, or wherein the homogenizing element is a two-dimensional diffractive element.

8. The laser projection device of claim 1 or 5, wherein the blue laser beam, the green laser beam and the red laser beam are emitted from the light source light outlet and then enter the light receiving part through a diffusion wheel.

9. The laser projection device of claim 1, wherein a half-wave plate is further disposed in a light path from the first light combining mirror to the second light combining mirror;

10. The laser projection device of claim 1, wherein a half-wave plate is further disposed in a light path between the light emitting surfaces of the blue laser component and the green laser component to the first light combining mirror, and the half-wave plate is disposed corresponding to the blue laser wavelength and the green laser wavelength.

11. The laser projection apparatus according to claim 1, wherein the red laser package has an emission power of 24W to 56W, the blue laser package has an emission power of 48W to 115W, and the green laser package has an emission power of 12W to 28W.