CN116125739A

CN116125739A - Laser projection device

Info

Publication number: CN116125739A
Application number: CN202310040491.1A
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: 2023-05-16
Also published as: WO2020253166A1; CN112114482A; CN112114482B

Abstract

The invention provides a laser projection device, wherein a light source comprises a red laser component, a green laser component and a blue laser component, and the red laser, the green laser and the blue laser are respectively emitted; the red laser component is arranged close to the light outlet of the light source; in the light combining path of the blue laser and the green laser or respectively aiming at the blue laser and the green laser, a static diffusion sheet is arranged, and the blue laser and the green laser are diffused and then combined with the red laser beam; a converging lens group is arranged at the light outlet of the light source and used for converging the three-color laser beams after light combination to narrow the light spots and then emergent from the light outlet of the light source; the diffusion wheel and the light receiving element are arranged between the converging lens and the light receiving component and are used for diffusing the three-color laser beams in a converging state; the light receiving component is a light pipe or a fly eye lens and is used for homogenizing the diffused three-color laser beams. The laser projection device can present a projection picture with high brightness and good color.

Description

Laser projection device

The present application is based on Chinese invention application 201910538765.3 (2019-06-20), the name of the invention: a divisional application for laser projection devices.

Technical Field

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

Background

The laser light source has the advantages of good monochromaticity, high brightness, long service life and the like, and is an ideal light source. Along with the improvement of the power of the laser device, the requirements of industrial application are met, and the laser is gradually used as a light source 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 has advantages of small etendue and high brightness as compared with an LED light source.

The lasers are classified into blue lasers, red lasers and green lasers according to the types of light emission, and respectively emit blue lasers, red lasers and green lasers. Because the light emitting mechanism is different, as shown in fig. 17, the red laser light emitting chip has two light emitting points, but one light emitting chip corresponds to one collimating lens, so that the effect of one collimating lens on two light emitting points is worse than the effect of one collimating lens on one light emitting point, the angle of divergence of the red laser light after exiting from the light emitting surface of the laser component is larger than that of the other two color lasers, however, in practical application, the light path system is shared by the three color lasers, and in the light beam transmission process, the optical lens generally has a light receiving range or light processing efficiency within a certain angle range, and in the case of the red laser, the light beam capacity within a large angle range is easy to lose due to the rapid divergence, so that the light loss rate of the red laser is generally large, and the loss rate is difficult to estimate and difficult to solve by a power compensation method.

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

Disclosure of Invention

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

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

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

the third light combining mirror reflects the red laser, the blue laser and the green laser to a light source light outlet; wherein the first light converging lens, the second light converging lens and the third light converging lens are arranged in parallel

Further, the first light converging lens and the second light converging lens have light reflectivity which is larger than light transmissivity;

Further, the luminous power of the green laser component is smaller than the luminous power of the red laser component and the blue laser component;

further, the light spot size of the red laser reaching the second light combining lens is larger than that of the blue laser and the green laser;

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

further, a diffusion sheet is arranged in the optical path from the first light converging lens to the second light converging lens and used for diffusing and transmitting the green laser light and the blue laser light;

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

further, the three-color light source beam enters the light receiving component through the diffusion wheel after exiting from the light source light outlet;

further, a half-wave plate is arranged in the optical path from the first light converging lens to the second light converging lens;

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 the optical paths between the luminous surfaces of the blue laser component and the green laser component and the first light combining mirror, and the half-wave plates are respectively arranged corresponding to the blue laser wavelength and the green laser wavelength;

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 colors of laser are different;

further, the light emitting power of the red laser component is 24W-56W, the light emitting power of the blue laser component is 48W-115W, and the light emitting power of the green laser component is 12W-28W.

The laser projection device of one or more embodiments uses a three-color laser light source, red laser is output from a light source light outlet after twice reflection, blue laser is output from the light source light outlet after once transmission and twice reflection, and green laser is output from the light source light outlet after twice reflection and once transmission, the light path of the red laser is shortest, and the total number of the experienced transmission and reflection is minimum, so that the light loss of the red laser in the light path is smaller, the maintenance of the power ratio or the color ratio of the three-color laser light beam is facilitated, 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 of the prior art, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it will be obvious that the drawings in the following description are some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort to a person skilled in the art.

FIG. 1 is a schematic diagram of the overall 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 view of another optical principle of a light source according to an embodiment of the present invention;

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

FIG. 5 is a block diagram of an ultra-short focal projection screen in accordance with an embodiment of the present invention;

FIG. 6 is a graph of the reflectivity of the projection screen versus the projection beam of FIG. 5;

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

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

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

FIG. 10 is an exploded view of another laser assembly according to an embodiment of the invention;

FIG. 11 is an exploded view of yet another laser assembly according to an embodiment of the invention;

fig. 12 is a schematic structural diagram of an MCL laser;

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

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

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

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

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

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

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

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

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

FIG. 22 is a schematic view of a light spot in an optical 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 the polarization directions of P light and S light;

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

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

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

FIG. 29 is a schematic view of another principle of a laser projection path according to an embodiment of the present invention;

reference numerals illustrate:

10-a laser projection device, 101-a housing;

100-light source, 102-light source shell, 1021-window, 104-fixed bracket, 1041-light transmission window, 1042-third sealing element; 105-sealing glass, 1051-first seal, 1052-second seal, 106-first combiner, 107-second combiner, 108-third combiner, 109-homogenizing element, 110-blue laser assembly, 111-converging lens set, 112-diffuser, 120-green laser assembly, 130-red laser assembly, 121, 131, 141, 151, 140-half wave plate;

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

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

400-projection screen, 401-substrate layer, 402-diffusion layer, 403-uniform dielectric layer, 404-fresnel lens layer, 405-reflective 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, fluid supplements-612, 613-heat conducting blocks.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

First, the structure and operation of the laser projection apparatus of 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 device, where the laser projection device 10 includes a complete machine housing 101, and further includes a light source 100, a light machine 200, and a lens 300 according to optical functional parts, where the optical parts have corresponding housings to be wrapped, and achieve a certain sealing or airtight requirement, for example, the light source 100 is airtight, so that the light attenuation problem of the light source 100 can be better prevented. The light source 100, the optical engine 200, and the lens 300 are installed in the whole machine housing 101. The optical engine 200 and the lens 300 are connected and disposed along a first direction of the overall housing 102, as shown in fig. 1, the first direction may be a width direction of the overall housing, or according to a usage manner, the first direction is opposite to a viewing direction of a user. The light source 100 is disposed in a space enclosed by the optical engine 200, the lens 300 and a part of the whole machine housing 101. The light source 100 is a pure three-color laser light source, and emits red laser light, blue laser light, and green laser light.

Thus, in the present example, the light source 100 is configured to provide light source illumination for the light engine 200, and in particular, the light source 100 provides illumination light beams for the light engine 200 by sequentially and synchronously outputting three primary color illumination light beams.

The light source 100 may also be a non-time-sequential output, where there are overlapping output periods of different primary colors, such as a red and a green overlapping output period, to increase the proportion of yellow in the beam period, so as to facilitate the improvement of the brightness of an image, or the red, green and blue colors are simultaneously lightened in a part of the periods, and the three colors are overlapped to form white, so that the brightness of a white field can be improved.

And, when other types of light modulation components are applied, the three primary colors of light in the light source section can be simultaneously lighted to output mixed white light in cooperation with the three-plate type LCD liquid crystal light valve. In this example, the light source unit 100 outputs three primary colors of light in a time series manner, and the human eye recognizes the colors of light at a time point which is not yet recognized by the human eye according to the three-color mixing principle, and the perceived light is still mixed white light. 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 in parallel and are perpendicular to the blue laser component in space position, namely, the side face of the light source shell where the green laser component and the red laser component are located is perpendicular to the side face of the light source shell where the blue laser component is located, and the two side faces are perpendicular to the bottom face of the light source shell or the bottom face of the whole machine shell.

Referring to fig. 2, a schematic diagram of an optical path principle of the light source 100 is shown, a light beam emitted by the red laser component is emitted from the light source light outlet after being reflected twice, a light beam emitted by the green laser component is emitted from the light source light outlet after being reflected twice and transmitted once, and a light beam emitted by the blue laser component is emitted from the light source light outlet after being transmitted twice and reflected once. In the schematic diagram of the optical path principle, the red laser light passes through the shortest optical path, and the total number of the passing transflectors is the smallest.

The three-color laser assemblies each output a rectangular light spot and are each vertically mounted on the side of the light source housing 102 along the long side direction of the respective rectangular light spot. Therefore, the laser light spots output by the three-color laser component can not form cross-shaped light spots during light combination, and the reduction of the size of the light combination light spots and higher homogenization degree are facilitated.

As shown in fig. 4, the light source housing 102 includes a plurality of sides, a bottom surface and a top cover, and a plurality of optical lenses in 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, so as to mount the plurality of laser components, and the light beams emitted by the laser components with any color are incident into the internal cavity of the light source 100 from the corresponding mounting windows, and 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, can be used for communicating the inner cavity of the light source with the outside to realize the exchange of air flow, when the temperature of the inner cavity of the light source rises, the inner air flow flows outwards, after the temperature is recovered and cooled, the outer air flow can also enter the inner cavity of the light source, and as the filter valve can be set to be an airtight waterproof filter membrane, the filter valve can filter particle dust and the like within a certain diameter range of the outside, the filter valve can block the outside and keep the cleanliness of the inner cavity of the light source. Alternatively, the air pressure balancing device is a telescopic air bag, and the air bag can be made of elastic rubber and used for increasing the volume of the air bag when the air pressure of the inner cavity of the light source is increased so as to relieve the air pressure of the inner cavity of the light source. The air pressure balancing device can be used as a pressure relief device, when the temperature of the inner cavity of the light source is excessively high, the pressure is relieved outwards through communication or the volume of the sealed space of the inner cavity of the light source is increased through forming the air accommodating structure, the air pressure of the inner cavity of the light source can be balanced, and the working reliability of each optical device in the inner cavity of the light source is improved.

Since the assembly structure of the three-color laser assembly and the light source housing is substantially the same, the connection relationship between the laser assembly and the light source housing will be described below by taking the assembly structure of any one of the three-color laser assemblies as an example for simplicity.

The three-color laser components are all MCL-type laser components, namely, a plurality of light emitting chips are packaged on a substrate to form a surface light source output. As shown in fig. 12, an MCL-type laser shown in fig. 13 includes a metal substrate 1102, and a plurality of light emitting chips (not shown in the drawing) are packaged on the metal substrate 1102, and the plurality of light emitting chips may be connected in series, or may be driven in parallel according to rows or columns. The light emitting chips can be arranged according to a 4X6 array, or can be arranged in other array modes, such as a 3X5 array, a 2X7 array, a 2X6 array, a 4X5 array, and the total light emitting power of lasers with different numbers of arrays is different. The metal substrate 1102 has leads 1103 extending from both sides thereof, and the leads are electrically connected to drive the light emitting chip to emit light. Covering the light emitting surface of the MCL laser, a collimator lens group 1101 is further provided, and the collimator lens group 1101 is usually fixed 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 collimate the laser beams correspondingly.

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

PCB boards

1104a,1104b disposed on the outer peripheral side of the MCL laser, and the

PCB boards

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

side circuit boards

1104a and 1104b almost parallel to the plane of the laser, wherein, 1104a and 1104b can be integrally formed and surround the outer side of the base board 1102 of the laser component, or 1104a and 1104b can also be two independent circuit boards, which enclose the laser component, so that the packaged laser component is basically a flat structure, which is convenient for installation, saves space and is beneficial to miniaturization of the light source equipment.

Fig. 7 and 8 are schematic diagrams of an assembly structure and an exploded structure of a laser assembly and a fixing bracket of any color respectively.

As shown in fig. 4, any color laser assembly is mounted at the window 1021 of the corresponding light source housing by the fixing bracket 104, and the fixing bracket 104 and the light source housing 102 are locked by screws, so that the laser assembly is fixed at the window 1021. Any color laser assembly includes an MCL laser assembly and a stationary mount.

The laser components of any color are locked on the fixed support through screws, and particularly, the metal substrate of the MCL laser is provided with an assembly hole which can be locked with the fixed support.

As shown in fig. 9, the fixing bracket 104 is a sheet metal part with a light-transmitting window 1041, the front surface of the light-transmitting window 1401 of the fixing bracket 104 is installed close to 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 order to improve the tightness of the mounting structure, a third sealing member 1042 is disposed at the back mounting position of the light-transmitting window 1041 of the fixing support, and the third sealing member 1042 is a frame-shaped rubber member with a folded edge, and can be sleeved on the front surface of the MCL-shaped laser, and then the MCL-shaped laser assembly is fixed at the mounting position. The third seal 1042 also can act as a buffer to prevent damage to the collimating lens group on the MCL-type laser surface 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 is mounted to the light source housing 102 at a position corresponding to the window 1021 as an assembly unit after being fixed to the fixing frame 104. Specifically, studs are arranged around the window 1021, and screws penetrate through the studs of the fixed support and are driven into the studs around the window.

Because the light source 100 is internally provided with a plurality of optical lenses, the optical lenses are precise components, and the energy density in the light beam transmission process is very high, if the cleanliness of the internal environment is not high, dust particles can accumulate on the surfaces of the precise lenses, so that the light treatment efficiency is reduced, the light attenuation of a light path is further caused, and the overall brightness of the whole laser projection device is also reduced. In this example, the dust prevention inside the light source can alleviate the light attenuation problem, specifically, as shown in fig. 10, a sealing glass 105 is further disposed at the window 1021, and the sealing glass 105 isolates the inner cavity of the light source from the laser component installed at the window 1021, so that external dust and the like cannot enter the inner cavity of the light source from the window opening. The sealing glass 105 can be arranged on the surface of the cavity in the light source, such as by bonding, and can also be arranged on one side of the light source shell close to the laser component, such as by arranging an installation position on the outer surface of the light source shell, and the laser component and the sealing glass are sequentially installed on the outer side of the window of the light source shell.

In the exploded structure shown in fig. 10, for the convenience of the above-described sealing glass installation, the sealing glass 105 is installed on the side of the window 1021 near the laser assembly in this example. The fixing bracket 104 also has a first receiving groove at the front 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 member 1051 and the second sealing member 1052, specifically, the second sealing member 1052 is placed in the second accommodating groove at the window 1021, a matching fixing groove for the sealing glass 105 is formed in the second sealing member 1052, the sealing glass 105 is placed in the fixing groove, the first sealing member 1051 is mounted in the first accommodating groove of the light transmitting window 1041 of the fixing bracket through interference fit, then any color laser assembly composed of the fixing bracket and the MCL laser assembly is mounted at the window 1021 of the light source housing, the first sealing member 1051 is in extrusion contact with the sealing glass 105, and the sealing glass 105 is clamped between the first sealing member 1051 and the second sealing member 1052 for fixing along with the completion of fixing of the laser assembly.

And in the above examples, the MCL-type laser component of any color is fixed on the fixed bracket through the shoulder screw, and the shock absorbing element is further arranged between the shoulder screw and the fixed bracket, so that noise transmission generated in the driving process of the laser at a higher frequency can be reduced.

The above description has been made of the assembled structure of the laser assembly and the light source housing. 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 is matched with an optical machine and a lens to perform projection imaging.

In the laser projection device provided in this embodiment, as shown in the schematic diagram of the light source light path shown in fig. 2, the intersection of the blue laser and the green laser is provided with the first light combining lens 106, the first light combining lens transmits the blue laser, reflects the green laser, and the intersection of the blue laser, the green laser and the red laser after light combining is provided with the second light combining lens, the second light combining lens reflects the red laser and transmits the blue laser and the green laser to the third light combining lens, and the third light combining lens outputs the red laser, the green laser and the red laser to the light source light outlet in a reflection manner.

Specifically, the optical axis of the light beam of the light emitting surface of the blue laser component is perpendicular to the optical axis direction of the light outlet of the light source, and the optical axes of the light beams emitted by the light emitting surfaces of the green laser component and the red laser component are parallel to the optical axis direction of the light outlet of the light source. The green laser emitted by the green laser component 120 is reflected by the first light combining mirror 106 and then enters the second light combining mirror 107, the blue laser emitted by the blue laser component 110 is transmitted through the first light combining mirror 106, and the blue laser and the green laser can be combined and output through the first light combining mirror 107.

The output direction of the blue laser light and the green laser light which are output by the first light combining lens 106 in a combining way is perpendicular to the output direction of the red laser light emitted by the red laser component 130, and the three light beams are intersected, a second light combining lens 107 is arranged at the intersection of the three light beams, the second light combining lens 107 reflects the red laser light, and transmits the green laser light and the blue laser light. The three-color laser beams are combined to form a beam which enters the third combining lens 108, the third combining lens 108 reflects the three-color laser beams to the homogenizing element 109, and the three-color laser beams are emitted from the light source light outlet after the light spots are reduced by the converging lens group 111.

In the light source structure illustration shown in fig. 4, the green laser assembly 120 and the red laser assembly 130 are mounted in parallel 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, the sides of the two light source housings being in a perpendicular relationship. The three-color laser components all output rectangular light spots and are vertically arranged on the side face of the light source shell along the long side direction of the respective rectangular light spots.

In the inner cavity of the light source, a plurality of converging lenses and converging lens groups are also arranged. Specifically, the first light combining lens is positioned between the blue laser assembly and the green laser assembly at the intersection of the two. The second light combining lens is obliquely arranged towards the light emitting surface of the red laser component, transmits red laser and reflects blue laser and green laser. The first light converging lens, the second light converging lens and the third light converging lens are arranged in parallel. Specifically, the first light converging lens, the second light converging lens and the third light converging lens are fixedly clamped on the bottom surface of the light source shell through the base, and the angles of the first light converging lens, the second light converging lens and the third light converging lens can be finely adjusted, such as within plus or minus 3 degrees, in consideration of assembly tolerance.

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

The third light converging lens is a reflecting lens, and the first light converging lens and the second light converging lens are both dichroic sheets.

And the light reflectivity of the first light combining lens and the second light combining lens is larger than the light transmissivity, for example, the light reflectivity of the two light combining lenses can reach 99 percent, and the transmissivity is usually 95 to 97 percent.

The three-color laser assemblies provided in this example are all MCL-type lasers, as shown in fig. 12, where the MCL lasers include a plurality of light emitting chips encapsulated on a metal substrate, and due to the difference in light emitting principles, the light emitting powers of the light emitting chips of different colors are also different, for example, the light emitting power of the green chip is about 1W per chip, and the light emitting power of the blue chip is above 4W per chip. When the three-color laser adopts the same number of chips, for example, the packaging types of 4X6 array are used, and the overall luminous power is different, for example, the luminous power of the green laser component is smaller than the luminous power of the red laser component and is also smaller than the luminous power of the blue laser component, and the luminous power of the red laser component is smaller than the luminous power of the blue laser component.

Meanwhile, in the above-described embodiments, the light emitting chip packages employing the same arrays of the red and blue laser assemblies and the green laser assembly are each, for example, a 4X6 array. However, due to the difference of the light emitting principles 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 light path transmission process, the red laser has a certain light receiving range or has better light processing performance in a certain angle range due to the large divergence angle of the red laser when passing through the same optical lens, so that the longer the light path or the light path of the red laser, the more serious the divergence degree of the red laser, and the lower the light processing efficiency of the following optical lens to the red laser. 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 is greater than that of the green laser and the blue laser after passing through the same length of the light path.

In the optical path shown in fig. 2, after being output along the light emitting surface of the blue laser component, the blue laser is transmitted twice, reflected once, and emitted from the light source light outlet after passing through the homogenizing element 109 and the converging lens group 111. For the green laser, the light is reflected twice, transmitted once, and then enters the homogenizing element 109 and the converging lens group 111 and exits from the light source light outlet. The red laser is reflected twice, and then enters the homogenizing element 109 and the converging lens group 111, and exits from the light source light outlet. It can be seen that the optical paths of the red laser are shorter than those of the blue laser and the green laser before being output from the light source light outlet, so that the optical loss generated by the red laser in the optical path transmission process can be reduced. And, under the condition that the influence of the light path on the light loss is not considered, the light energy can reach 99% by 99% =98% after the red laser light passes through the transmission of the second light combining lens and the reflection of the third light combining lens, and the calculation of the light energy efficiency of the red laser light is to consider that the divergence angle of the red laser light is not considered, and under the condition that the light loss with a large angle exists, only the influence of the transmittance and the reflection rate of the optical lens is considered.

When the influence of the transmittance and the reflectance on the light loss is only considered, the light energy output by the blue laser after the blue laser is reflected by the first light combining lens and the second light combining lens can reach 97% by 99% to be 93%, the light energy output by the third light combining lens after the green laser is reflected by the first light combining lens, the light energy output by the third light combining lens can reach 97% by 99% to be 95%. In practical applications, the light emission power of the blue laser may be higher, and the visual function of the human eye for blue may be relatively low. It can be seen that the red laser has minimal loss of reflectivity through the lens and its optical path is shortest. The red laser light is therefore minimally lost in the light path.

Based on the layout of the laser light sources, the loss of the laser beams of each color in the transmission process can be balanced well under the different optical characteristics of the lasers of each color, the light loss caused by the characteristic of easy consumption of red laser in a light path is reduced, the power ratio of the three-color laser is close to a preset value, obvious unbalance can not occur, and the realization of color ratio and expected white balance which accord with theoretical design is facilitated. When the three-color laser is output from the third beam combiner, the three light paths are the same, so that the consistent light loss is easy to achieve, and the unbalance inconsistency is weakened.

The light path formed by the arrangement of the lasers is L-shaped, is relatively regular, is beneficial to reducing the length of the shell in one direction, is beneficial to structural design, can reserve regular space for the shell, and is convenient for setting a heat dissipation device.

Above-mentioned laser subassembly all adopts MCL type laser subassembly, compare in traditional BANK type laser subassembly, the volume of MCL type laser subassembly is obviously less, consequently in this embodiment, its structure volume is compared when traditional use BANK type laser subassembly, make near the light source can reserve more space, provide convenience for heat dissipation design, for example the radiator, the fan put more nimble in the position selection, and also probably set up structures such as circuit board, also be favorable to reducing the length of complete machine structure in a certain direction, or the volume of complete machine.

And because the light source is usually a lens component beside the light source in the whole machine structure, and the light source is a heat source of the laser projection equipment, the L-shaped light path is arranged, so that the laser component is arranged as close as possible to one side of the whole machine shell, a space is reserved in the middle, and the laser component can also be used as an isolation space between the laser component and the lens, thereby preventing heat generated by the laser when the laser emits light from being rapidly transferred to precision optical lenses such as the lens and affecting the optical performance.

As a modification of fig. 2, unlike the optical paths shown in fig. 2, the positions of the blue laser component and the green laser component may also be exchanged, for example, as shown in fig. 3, the blue laser light emitted by the blue laser component 110 is reflected by the first light combining mirror 106 and then sequentially transmitted by the second light combining mirror 107, the light loss is about 5% by reflection of the third light combining mirror 109, the light loss of the green laser light is about 7% by reflection of the third light combining mirror 109, and the problem that the light loss of the green laser light is relatively high due to the layout of the light source can be alleviated or alleviated by increasing the light emitting period ratio of the green laser light in the circuit.

In the above embodiments, the light path of the red laser is set to be shortest, so as to reduce the transmission or reflection times of the red laser, or the red laser is set to pass through the reflection light path only, so that 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 ratio of the light beam power and the color of the three-color light source can be maintained, the white balance of the system is close to the theoretical set value, and higher projection picture quality is realized.

Referring to fig. 2 and 3, the laser projection apparatus uses the light source in the embodiment, and the three-color laser beam passes through the homogenizing element and the converging lens group after combining the light by the converging lens, so as to perform the homogenizing and beam shrinking treatment on the light beam, thereby improving the light collecting efficiency and homogenizing efficiency of the light receiving element in the following optical machine.

Specifically, as shown in fig. 2, the light source 100 further comprises a homogenizing element 109 and a converging lens group 111. The homogenizing element 109 is disposed between the third condensing lens 108 and the converging lens group 111. In particular, the homogenizing element may be a diffusion sheet having a regularly arranged microstructure, as shown in fig. 20. The microstructure of the diffusion sheet commonly used at present is random irregular, the microstructure of the homogenization diffusion sheet which is used in the light source framework and is regularly arranged is similar to the principle of homogenizing a light beam by a fly eye lens, the energy distribution of a laser beam can be changed from a Gaussian shape to a shape shown in fig. 21, the energy near the central optical axis of the laser is greatly weakened and is gentle as shown in fig. 21, the divergence angle of the laser beam is also increased, and therefore, the effect of homogenizing the energy is greatly superior to that of the diffusion sheet of the commonly used irregular microstructure.

The homogenizing diffusion sheet can be provided with microstructures regularly arranged on one side, and can also be provided with two sides.

After the homogenization of the homogenization diffusion sheet, the laser beam is subjected to the reduction of the light spot size through the converging lens group. On one hand, the high-energy laser beam is homogenized first, so that the impact on uneven energy distribution of the rear-end element can be reduced, and on the other hand, the homogenizing is performed first, and the difficulty of re-homogenizing the light spot after beam shrinking can be reduced.

The homogenization device 109 may be a two-dimensional diffraction device, or may achieve a preferable homogenization 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, and the two lenses are spherical lenses, and of course, aspheric lenses can also be used, but the spherical lenses are easier to control in terms of molding and precision than the aspheric lenses, and the cost can also be reduced. In this example, the converging lens group is used for converging the light beams, and the focal point of the converging lens group is arranged at the light receiving opening of the rear-end light receiving element, that is, the focal plane of the converging lens group is positioned at the light incident surface of the light receiving element, so that the light receiving efficiency of the light receiving element is improved.

In one implementation, the converging lens group is located at the light source outlet of the light source housing, specifically, the rear lens or the entire lens group in the converging lens group may be mounted at the light source outlet, and the housing around the converging lens group and the light source outlet is filled with a sealing member, such as a sealing rubber ring. Therefore, the converging lens group is fixed, and the airtight sealing of the cavity in the light source can be maintained, so that dust particles and the like brought in when the first light outlet is used as a light transmission window and is exchanged with external air flow are prevented. And the converging lens group is directly fixed at the first light outlet position, so that the light path is shortened, and the volume of the light source shell is reduced.

The light beam in a converging state output from the first light outlet of the light source is finally collected by a light receiving component of the light path of the light machine. As shown in the schematic diagram of the optical path principle in fig. 18, in this example, the light receiving member 250 is a light pipe. The light guide pipe is provided with a rectangular light incident surface and a rectangular light emergent surface. The light guide is used as a light receiving component and a light homogenizing component. 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 in the light guide for multiple times and exits from the light emergent surface. As the homogenizing diffusion sheet is arranged in the front-end light path, the light is homogenized by the light guide, so that a better three-color mixing homogenizing effect can be achieved, and the quality of the illumination light beam is improved.

Since the light source is a pure three-color laser light source, speckle is a phenomenon peculiar to laser, and in order to obtain higher projection picture display quality, the three-color laser needs to be subjected to speckle elimination treatment. In the example, a diffuser wheel 260, i.e. a rotating diffuser, is also provided between the converging mirror group 111 and the light receiving 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 incident surface of the light guide pipe is about 1.5-3 mm. The diffusion wheel can diffuse the light beam in a converging state, increases the divergence angle of the light beam and increases the random phase. And, because the human eye has different speckle sensitivity to different color lasers, 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, the second partition is used for transmitting blue laser and green laser, and the divergence angle of the first partition is slightly larger than that of the second partition. Or the three subareas respectively correspond to red laser, green laser and blue laser, wherein the divergence angle of the red laser subareas has the relationship of maximum divergence angle of the red laser subareas and minimum divergence angle of the blue laser subareas. When the diffusion wheel has a corresponding zone, the rotation period of the diffusion wheel may coincide with the period of the light source. In general, the rotation period of the diffusion wheel is not particularly limited when the diffusion wheel is a diffusion sheet.

The light guide has a certain light receiving angle range, for example, light beams within a positive and negative 23-degree range can enter the light guide and are utilized by a rear-end illumination light path, and other light beams with large angles become stray light and are blocked outside, so that light loss is formed. The light emitting surface of the diffusion wheel is close to the light entering surface of the light guide pipe, so that the light quantity of the diffused laser beam which is received into the light guide pipe can be improved, and the light utilization rate is improved.

The light receiving member may be a fly eye lens member.

And, as described above, since the homogenizing diffusion sheet 109 is provided in the front-end optical path, the light source beam is homogenized, then converged by the converging mirror group 111, and incident on the diffusion wheel 260. The laser beam passes through a static diffusion sheet and then passes through a moving diffusion sheet, so that on the basis of homogenizing the laser beam by the static diffusion sheet, the laser beam is diffused and homogenized again, the homogenizing effect of the laser beam can be enhanced, the energy ratio 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 appearing on a projection picture can be greatly improved.

In the light source provided in the above embodiment, the light beam of the light source is incident into the light guide tube to be re-homogenized, and the light spot distribution measured by the applicant on the light incident surface of the light guide tube will show a relatively obvious boundary phenomenon between the inner and outer colors. For example, the focused light spots are circular, the outermost ring is red, and the apertures of different concentric circles such as purple, blue and the like are sequentially inwards. As shown in fig. 22. It has been found by research that the divergence angle of the fast and slow axes of the red laser assembly is larger than the divergence angles of the blue laser and the green laser due to the difference of the light emission principles as mentioned above. Although in this example the three-colour laser assemblies are arranged in an array using the same number of chips, the size is uniform in terms of volume appearance, due to the characteristics of the red laser itself, this results in a red laser beam having a spot size during transmission that is larger than the spot sizes of the blue and green lasers. This now exists when trichromatic light is combined and as the optical path transmission distance increases, the divergence angle increases at a greater rate than the laser light of the other color, so that although trichromatic light will be homogenized, condensed and possibly again diffused and homogenized by the rotating diffuser, there will always be a larger spot size of the red laser light. This phenomenon is also exhibited by the test spot at the light entrance face of the light pipe.

In order to improve the superposition ratio of the three-color laser spots, the length of the light guide tube can be increased to improve the light mixing homogenization effect, but the light path length is increased, and the structural volume is increased.

In this example, a solution is proposed, specifically, as shown in fig. 19, on the basis of the optical path schematic diagram provided in fig. 2, a diffusion sheet 112 is disposed in the light path of the combined blue laser and green laser, and the blue laser and green laser are first diffused and then combined with the red laser beam. Wherein the diffusing sheet 112 is disposed in the optical path between the first combining mirror 106 and the incident second combining mirror 107. It is of course also possible to provide stationary diffusion plates for the blue and green laser light, respectively, for example in the light paths between the light emitting surfaces of the two color laser assemblies and the corresponding light combining lenses, respectively.

Through setting up a slice diffusion piece in the light path of blue laser and green laser, can expand the beam to blue laser and green laser, for example set up to 1 degree ~ 3 degrees diffusion angle, after this diffusion piece, blue laser and green laser through expanding beam combine the light with red laser again, and the facula size of trichromatic laser is equivalent this moment, and the facula coincidence degree improves. The three-color light spots with higher overlap ratio are also beneficial to homogenization and speckle dissipation of the subsequent light path, and the quality of the light beam is improved.

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

In the 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 laser and the green laser are S light. The three-color light beams projected and imaged by the laser projection device have different polarization directions.

In practical applications, in order to better restore color and contrast, a laser projection device is usually further matched with a projection screen with higher gain and contrast, such as an optical screen, so as to better restore a projection screen with high brightness and high contrast.

An ultra-short focal projection screen is shown in fig. 5, which is a fresnel optical screen. Along the projection beam incidence direction, the light source comprises a substrate layer 401, a diffusion layer 402, a uniform dielectric layer 403, a Fresnel lens layer 404 and a reflection layer 405. The thickness of the fresnel optical screen is typically between 1 and 2mm, with the substrate layer 401 occupying the greatest proportion of the thickness. 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 is first transmitted through the substrate layer 401, then enters the diffusion layer 402, diffuses, and then enters the uniform dielectric layer 403, where the uniform dielectric layer is a uniform light-transmitting medium, for example, the material of the uniform dielectric layer is the same as that of the substrate layer 401. The light beam is transmitted through the uniform dielectric layer 403, enters the fresnel lens layer 404, the fresnel lens layer 404 converges and collimates the light beam, and the collimated light beam is reflected by the reflective layer and then returned to pass through the fresnel lens 404 again, the uniform dielectric layer 403, the diffusion layer 402, and the base material layer 401, and enters the eyes of the user.

The applicant finds that the ultra-short focal projection picture using the three-color laser light source can generate local color cast in the research and development process, so that uneven chromaticity such as color spots, color blocks and the like can be caused. The reason for this phenomenon is that, on the one hand, in the currently applied three-color laser, the polarization directions of the laser beams with different colors are different, and in the optical system, a plurality of optical lenses, such as lenses and prisms, are usually arranged, and the reflectivity of the optical lenses for P-polarized light and S-polarized light is different, for example, the transmissivity of the optical lenses for P-polarized light is larger than the reflectivity for S-polarized light, and on the other hand, due to the structure of the screen material, as the incident angle of the ultra-short focal projection beam changes, the ultra-short focal projection screen itself can present obvious changes in the transmissivity and reflectivity of the beams with different polarization directions, as shown in fig. 6, when the projection angle is about 60 degrees, the reflectivity of the projection screen for P-polarized light and the reflectivity for the S-polarized light are different by more than 10 percent, that is, so that the reflectivity of the ultra-short focal projection screen for P-polarized light is more than the reflectivity for S-polarized light, and the P-polarized light is reflected by the screen into eyes, and when the reflected by the screen into eyes, the contrast is also present in the different colors, the three-polarized light is obviously caused when the different colors are projected on the different colors, and the opposite polarization directions are different, and the three-polarized light is caused to the opposite to the different polarization directions, especially when the partial color is different.

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

In this embodiment, the blue laser component and the green laser component are disposed adjacently, and a phase retarder is disposed in the output paths of the blue laser and the green laser and before the blue laser and the green laser are incident on the third combiner, so that 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, and the color cast phenomenon of the projection picture caused by different polarization directions is solved.

First, the operation principle of the phase retarder will be described. The retarder is a wavelength corresponding to a certain color, and affects the degree of phase change of the transmitted light beam by the thickness of the crystal growth, and in this example, the retarder is a half-wave plate, also called λ1/2 wave plate, and can change the phase of the light beam corresponding to the wavelength of the color by pi, that is, 180 degrees, and rotate the polarization direction by 90 degrees, for example, change the P light into the S light or change the S light into the 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 the coordinate system formed in the direction perpendicular to the optical axis W, where Ex, ey can be expressed by using a light wave formula. The P light can be considered as a spatial synthesis of two dimensional waves of 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 pi change amounts, and after the phase changes of the light waves of a certain moment in the original polarization direction are carried out by 180 degrees, the light waves of two direction components are overlapped, and the polarization positions of the two direction components are changed at the space positions, so that b1, c1 and a1 are formed, and the light in the S polarization direction is formed. The above spatial position changes of b0, c0, a0 and b1, c1, a1 are only illustrative.

After passing through the half-wave plate, the light 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 of corresponding wavelengths, specifically half-wave plates, are respectively disposed in the light-emitting paths of the blue laser component and the green laser component. In this example, the center wavelength of the blue laser is about 465nm, the center wavelength of the green laser is about 525nm, and when the half-wave plate 121 is located in the light-emitting path of the blue laser, which is set corresponding to the center wavelength of the blue laser, and the half-wave plate 131 is located in the light-emitting path of the green laser, which is set corresponding to the center wavelength of the green laser, in the optical path schematic diagram shown in fig. 27, it is possible to change the polarization directions of both the green laser and the blue laser by 90 degrees, from S light to P light.

Based on the light path principle, in one implementation, the half-wave plate can be arranged in the inner cavity of the light source and positioned between the inner side of the light source shell and the light converging lens corresponding to the laser component, and the half-wave plate is fixed by arranging the lens base on the bottom surface of the light source shell.

Alternatively, the half-wave plate may be disposed inside a window formed in the light source housing for the laser assembly, for example, by gluing or fixing the half-wave plate to the inside of the window.

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

Alternatively, when the sealing glass is provided at the window glass, the half-wave plate may be located between the sealing glass and the light emitting face of the laser assembly. As shown in the exploded view of the laser assembly in fig. 11, a support table (not shown) is further provided on the front surface of the light-transmitting window 1041 of the fixing support of the laser assembly, and the half-wave plate 140 may be fixed on the support table by glue, and a receiving groove is further provided around the support table for receiving the first sealing member 1051. Fig. 9 shows a schematic view of a half-wave plate mounted on the front surface of a fixing frame, wherein the half-wave plate 140 is mounted at the position of a light-transmitting window 1041 of the fixing frame and is fixed by dispensing through a peripheral dispensing slot. Wherein, the length and width ranges of the half-wave plate 140 are 25-30 mm and 21-28 mm respectively; the length and width ranges of the transparent windows of the fixing support are respectively 20-24 mm and 18-20 mm, for example, in one embodiment, 30mm x 28mm is selected for the half-wave plate, and the size of the transparent windows is 24mm x 20mm.

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

In the light source structure, the half-wave plates with corresponding colors are arranged on the fixing supports of the blue laser component and the green laser component, so that the polarization polarity of the light beam changes by 90 degrees after passing through the corresponding half-wave plates. The green laser is P light when entering the first light converging lens, the blue laser is P light when entering the first light converging lens, so that the light beams output after the blue laser and the green laser are combined through the first light converging lens are P light polarized light, the polarization direction of the light beams is the same as that of the red laser, the second light converging lens outputs three-color light beams with the same polarization direction, the three-color light beams are processed through homogenization, beam contraction and the like, enter an optical machine illumination light path, enter a lens through DMD reflection, are projected onto a screen to form images through the lens, and the phenomenon of uneven chromaticity such as color spots, color blocks and the like of a projection picture can be eliminated or greatly relieved due to the fact that the three-color polarization directions are the same.

As a modification of the above-described embodiment, the blue laser light and the green laser light are combined first and then combined with the red laser light in this example, and the half-wave plate may be disposed in the optical path after the combination of the blue laser light and the green laser light and before the combination of the red laser light. Specifically, as shown in fig. 28, another schematic view of the light path principle of the light source is provided, and a half-wave plate 141 may be disposed between the first light combining mirror 106 and the second light combining mirror 107 to 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 respectively output S polarized light, the green S light is incident to the first combiner 106 and reflected, the blue S light is incident to the first combiner 106 and transmitted, the first combiner 106 combines the blue laser and the green laser, which are both S light, and then passes through the half-wave plate 141, the half-wave plate 141 changes the polarization directions of the green laser and the blue laser, and then the green S light is incident to the second combiner 107.

Specifically, the half-wave plate 141 may be set for a wavelength of one of the colors, such as a wavelength of green laser light, which passes through the half-wave plate and then rotates in the polarization direction by 90 degrees, from the original S light to P light. After the blue laser passes through the half-wave plate, the wavelength of the half-wave plate is not set corresponding to the blue wavelength, so that the polarization direction deflection of the blue laser is not 90 degrees, but is close to the P polarization direction, and the visual function of human eyes on blue is lower, the sensitivity on blue is lower, and visual discomfort such as red and green is more obvious when color cast occurs. Or, the half-wave plate 141 may be set for the intermediate values of the blue and green central wavelengths, so that the polarization directions of the green laser and the blue laser are changed by not 90 degrees, but are close to 90 degrees, while the blue laser and the green laser are not deflected from the S light to the 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 color such as "color spots", "color blocks" presented in the local area on the projection screen can be improved, and the principle is not repeated.

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 scheme of disposing the half-wave plate shown in fig. 28 is equally applicable to the optical path architecture provided by the optical path schematic diagrams shown in fig. 2, 3, 18 or 19. The working principle is not repeated.

In the optical system, the same optical lens has the same transmittance for P light and S light of different wavelengths, and the same reflectance for P light and S light. The optical lenses herein include various optical lenses in the entire laser projection apparatus, such as a converging lens group, a lens group in an illumination light path in a light machine section, and a refractive lens group in a lens section. Thus, when the light beam from the laser light source passes through the entire projection optical system, the difference in transmittance is a result of the superposition of the entire system, which is more remarkable.

Before the half-wave plate is also not added, especially when the primary light is P light and S light linearly polarized light, the selective transmission of the P light and the S light is obvious whether the primary light is an optical lens of an optical system or a projection screen. For example, the transmittance of the projection screen for P light (red light) is obviously higher than that for S light (green light and blue light) according to the different incident angles of the projection beams, which causes the problem of local chromaticity non-uniformity of the projection picture, namely 'color spots', 'color patches' on the picture.

In the embodiments provided above, by providing 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 provided for the blue laser and the green laser respectively, the polarization directions of the blue laser and the green laser can be changed by 90 degrees, in this example, the polarization direction of the blue laser and the green laser is changed from the polarization direction of the S light to the polarization direction of the P light, which is consistent with the polarization direction of the red laser, so that when the blue laser and the green laser which are changed into the P polarized light pass through the same optical imaging system and are reflected into human eyes through the projection screen, the transmittance of the blue laser and the green laser in the optical lens is equivalent to the transmittance of the red laser which is P light, the consistency of the light processing process is close, and the reflectance difference of the projection screen to the three-color laser is also reduced, the consistency of the light processing process of the three-color primary light is improved, the color phenomenon of the color spot and the color block on the local area on the projection screen can be fundamentally eliminated, and the projection screen display quality is improved.

And when a half wave plate is provided in the light combining path of the blue laser light and the green laser light, the polarization direction of one of the green laser light and the blue laser light may be changed by 90 degrees, or the polarization directions of the laser light of both colors may be changed by not 90 degrees, but both are close to 90 degrees. The polarization difference of the red laser P light can be reduced, and based on the principle, the consistency of the whole system in the light treatment process of the red, green and blue three primary colors can be improved, and the technical problem of uneven color such as color spots, color blocks and the like appearing in a local area on a projection picture can be solved.

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

As a technique for solving the above-described problem of uneven color such as "color spots" and "color patches" appearing on the projection screen, the present embodiment provides a laser projection apparatus employing a light source section 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 combiner 107.

The arrangement of the half-wave plate can be seen from the arrangement of the half-wave plate for the blue laser light and the green laser light in the above embodiment.

For example, the half-wave plate can be arranged in the inner cavity of the light source and positioned in the light path between the inner side of the light source shell and the third light combining lens, and the half-wave plate is fixed by arranging the lens base on the bottom surface of the light source shell.

Alternatively, the half-wave plate may be disposed inside a window formed in the light source housing for the red laser assembly, for example, by gluing or fixing the half-wave plate to the inside of the window.

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

Alternatively, when the sealing glass is provided at the window glass, the half-wave plate may be located between the sealing glass and the light emitting face of the laser assembly. The specific installation manner can also refer to the description of fig. 11, and will not be repeated here.

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

It should be noted that, the scheme of setting the half-wave plate for the red laser is also applicable to the optical path schematic diagrams shown in fig. 2, 3, 18 and 19 of the present invention, and the principles thereof are not repeated.

In the above example, by providing the half-wave plate in the red laser output light path, the red laser light which is originally P polarized light is converted into S polarized light, and the polarization directions of the blue laser light and the green laser light are identical, so that the polarization directions of the three colors of the system are identical, and the principle description of the foregoing embodiment is referred to, the transmittance of the projection optical system for the red laser light, the blue laser light and the green laser light which are both S polarized light is reduced compared with the difference when the red laser light, the blue laser light and the green laser light are polarized in different polarization directions, and the reflectivity of the ultra-short focal projection screen for the three colors which are both S polarized light is also basically identical, so that the consistency of light processing for each primary color is improved, and the phenomena of uneven chromaticity such as "color spots", "color patches" and the like which are presented on the projection picture can be eliminated or improved.

And in the above embodiments, the light emitting surface of the laser is rectangular, and correspondingly, the retarder is correspondingly disposed in the light output path of one color or two colors, and the shape of the retarder 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 higher energy, the optical lens, such as a lens, and a prism, will be accompanied by a temperature change during operation, the optical lens will form internal stress during the manufacturing process, and this internal stress will be released along with the temperature change, and stress birefringence will be formed, and this stress birefringence will cause different phase delays for beams with different wavelengths, which can be regarded as a secondary phase delay. In the actual optical path, the phase change of the light beam is based on the effect of the superposition of the stress birefringence effects of the half-wave plate and the optical lens, and the amount of retardation inherently caused by such an optical lens varies depending on the system design. The technical solutions of the embodiments in the present application may preferably correct the secondary phase retardation caused by the actual system to approach or reach the theoretical value of 90 degrees of change of the polarization direction of the light beam when applied.

The half-wave plate has an optical axis in the plane of its flat plate, as shown in fig. 23, where the optical axis W of the half-wave plate is in a spatial perpendicular relationship with the optical axis O of the system, and the optical axis of the half-wave plate is parallel to the long side or the short side of the half-wave plate. In a specific application of the embodiment scheme described above, as shown in fig. 26, a half-wave plate is set to: and rotating the half-wave plate according to a preset angle, such as C degrees, along the long side or short side direction of the rectangular half-wave plate, as shown by a dotted line in the figure. Through the deflection of the angles, the optical axis of the half wave plate is deflected by about plus or minus C degrees, so that the phase of the light beam is changed to about 180 degrees plus or minus 2 degrees, and the light beam is overlapped 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 the above embodiments of the present application, C may take a value of 10.

In one or more embodiments, for the tricolor light with different polarization directions of the laser projection light source, by arranging the half wave plate in the light output path of one color or two colors in the laser projection device light source, the polarization direction of the corresponding transmitted tricolor light with the polarization direction of other colors is changed to be consistent, and the polarization polarity of the tricolor light output by the laser projection device is the same, so that when the laser beams 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 for tricolor laser is close, the reflectivity difference of the projection screen for tricolor laser is also reduced, the consistency of the light processing process of the whole projection system for tricolor light is improved, the phenomenon of uneven chromaticity such as 'color spots' presented in a local area on a projection screen can be fundamentally eliminated, and the display quality of the projection screen is improved.

In a laser projection device, the light source is the primary heat source, and the high density energy beam of the laser is also directed to the surface of the optical lens to generate heat. DMD chips are a fraction of an inch in area, but are required to withstand the beam energy required for the entire projected image, and generate very high amounts of heat. On the one hand, the laser has a set working temperature to form stable light output, the service life and the performance are both considered, meanwhile, the device comprises a plurality of precise optical lenses, especially the ultra-short focal lens comprises a plurality of lenses, if the temperature inside the whole device is too high, heat is gathered, the lens in the lens can be caused to generate a 'warm-floating' phenomenon, and the imaging quality can be seriously reduced. And the components such as the circuit board device and the like are driven by the 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 the laser projection device to work properly.

Specifically, as shown in fig. 15 and fig. 16, the heat conducting block 603 is in contact with a heat sink of the green or blue laser component to conduct heat, the outer surface of the heat pipe 602 is in contact with the heat conducting block to realize heat transfer, one end of the heat pipe 602 in contact with the heat conducting block 603 is a hot end, the other end is in contact with the heat radiating fins to be a cold end, the heat pipe is a closed system with liquid inside, and heat conduction is realized through liquid-gas-liquid change. The cooling fins contacted with the cold end of the heat pipe are cooled by air cooling, so that the cold end of the heat pipe is 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 heat of the heat source component and returns the heat to the cold row, the cold row is cooled, and cooled cooling liquid, such as water, flows back to the cold head again, and heat conduction is carried out on the heat source in a circulating mode. In the liquid cooling circulation system, the liquid cooling circulation system further comprises a pump for driving the cooling liquid in the liquid cooling circulation system to keep flowing, and in the example, the pump and the cold head are integrally arranged, so that the reduction of the volume of components is facilitated, and the cold head 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 this example, still include the fluid infusion ware for fluid infusion to the liquid cooling circulation system for the liquid pressure in the whole liquid cooling circulation system is greater than system external pressure, and the outside air can not get into inside the circulation system because the evaporation of coolant liquid or the pipeline joint leakproofness are not good like this, causes circulation system internal noise, produces cavitation phenomenon and causes the damage to the device even.

Compared with an air cooling heat dissipation system, the liquid cooling circulation system is flexible, the volumes of the cold head and the cold row are smaller than those of the traditional heat dissipation fins, and the liquid cooling circulation system is more various in the selection of the shape and the structure position. Because the cold head and the cold row are communicated through the pipeline and always form a circulating system, the cold row can be arranged close to the cold head, and can also have other relative position relations, which is determined by the space of the laser projection equipment.

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

In a laser projection device, the light source 100 is a laser light source, and the different color laser assemblies included have different operating temperature requirements. Wherein the operating temperature of the red laser assembly is less than 50 ℃, and the operating temperatures of the blue laser assembly and 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 for the circuit board portion, the temperature control of the different electronic devices is different, typically between 80 ℃ and 120 ℃. Therefore, the temperature tolerance value of the optical part is generally lower than that of the circuit part, so that air flows are blown from the optical part to the circuit part, and the two parts can achieve the heat dissipation purpose and maintain the normal operation of the device.

It should be noted that, since the operating temperature of the red laser component is less than 50 ℃, for example, when the operating temperature is controlled below 45 ℃, the difference between the surface temperature of the cold row and the surface temperature of the cold head is controlled within the range of 1-2 ℃ by using a liquid cooling heat dissipation method, that is, if the surface temperature of the cold head is 45 ℃, the surface temperature of the cold row is 43-44 ℃, wherein the surface temperature of the cold head refers to the temperature of the contact surface of the cold head and the heat sink of the laser component. Specifically, the first fan sucks in air at an ambient temperature, which is typically 20-25 ℃, cools the cold row by air cooling, and reduces the surface temperature of the cold row to 43 ℃. The working temperature of the blue laser component and the green laser component is below 65 ℃, the temperature of the radiating fins is required to be 62-63 ℃, and the temperature difference between the temperature of the radiating fins and the temperature of the heat sink of the laser component is within the range of 2-3 ℃. It can be seen that the temperature of the cold row is lower than the temperature of the heat radiating fins, and therefore, the cold row is disposed at the front end of the heat radiating path, also before the heat radiating fins in the heat radiating path. The air flow formed by the rotation of the fan dissipates heat of the cold row and then blows the air flow to the radiating fins again, so that the radiating fins can still dissipate heat.

Similarly, since the working temperature of the lens is controlled at 85 ℃, and the temperature of the radiating fins is 63 ℃, the working temperature of the lens is still lower than that of the lens, 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 air flow after the lens is subjected to heat dissipation is still cold air flow relative to most circuit boards, and the air flow can still continue to flow through the circuit boards to conduct 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 above structural layout manner is also beneficial to designing a heat dissipation path, and the heat dissipation airflow can flow from the component with the lower working temperature threshold to the component with the higher working temperature threshold, so that heat can be dissipated for a plurality of heat source components in one heat dissipation path in sequence, thereby not only meeting the working heat dissipation requirements of the plurality of heat source components, but also achieving high heat dissipation efficiency of the whole machine.

In another implementation, the heat dissipation fins may be improved in heat transfer coefficient by improving the structure of the fin surface, increasing the heat dissipation area, or increasing the flow rate of wind.

In the laser projection apparatus provided in the above embodiment, the light emission power range of the red laser component may be 24W to 56W, the light emission power range of the blue laser component may be 48W to 115W, and the light emission power range of the green laser component may be 12W to 28W. Preferably, the light emitting power of the red laser assembly is 48W, the light emitting power of the blue laser assembly is 82W, and the light emitting power of the green laser assembly is 24W. All the three-color lasers adopt MCL type laser components, and compared with a BANK type laser, the volume is greatly reduced under the condition of outputting the same luminous power.

In the laser projection apparatus, the heat dissipation requirement of the light source 100 is the most stringent, and the operation temperature control is relatively low in the whole apparatus. In particular, the operating temperature of the red laser assembly is lower than the operating temperature of the blue and green laser assemblies, due to the light emission principle of the red laser. Blue and green lasers are generated using gallium arsenide luminescent materials, and red lasers are generated using gallium nitride luminescent materials. The red laser has low luminous efficiency and high heat productivity. The red laser emitting material also requires more severe temperature. Therefore, when the light source component formed by the three-color lasers is subjected to heat dissipation, different heat dissipation structures are required to be arranged according to the temperature requirements of different laser components, so that the lasers of each color can be ensured to work in a better state, the service life of the laser components is prolonged, and the luminous efficiency of the laser components 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 liquid cooling heat dissipation can be more accurate and has smaller range, for example, the temperature difference control is 1-2 ℃. The red laser component with lower working temperature threshold adopts a liquid cooling heat dissipation mode, and the blue laser component and the red laser component with relatively higher working temperature threshold adopt an air cooling heat dissipation mode, so that the red laser can be cooled with lower heat dissipation cost under the condition of meeting the working temperature requirement of the red laser, and the smaller temperature difference control can be met, and the rotating speed requirement of a fan can be reduced. However, the component cost of the liquid cooling heat dissipation system is higher than that of the air cooling heat dissipation system.

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

Specifically, referring to fig. 14, the metal substrate on the back side of the red laser assembly 110 is connected to the cold head through a first heat-conducting block 613, and the area of the first heat-conducting block 613 is larger than the area of the heat-conducting surface of the cold head, and the area of the first heat-conducting block is also larger than the area of the heat-conducting surface of the back side of the red laser assembly 110. Thus, the heat of the heat sink of the laser component can be quickly concentrated and transferred to the cold head, and the heat conduction efficiency is improved.

In the heat dissipation system structure shown in fig. 14, the outlet of the cold head 610 is connected to the inlet of the cold row 611 through a pipe, and the outlet of the cold row 611 is connected to the inlet of the cold head 610 through a pipe. In the liquid cooling circulation system formed by the cold head 610, the cold row 611 and the pipeline, as described above, the liquid compensator 612 is further provided to supplement the cooling liquid for the system circulation, so that the liquid compensator can be provided at a plurality of positions of the whole circulation system, and one or more liquid compensators can be connected with the pump or can be arranged near the cold row according to factors such as system structural space.

In this example, the blue laser assembly and the green laser assembly are identical in operating temperature control, sharing a common heat sink fin structure. Specifically, as shown in fig. 15 and 16, in the blue laser assembly 120, the heat sink on the back side of the green laser assembly 130 is in contact with the heat pipe 602 through the heat conducting block 603, and the heat pipe 602 extends into the heat radiating fin 601. For example, for a blue laser component, the heat conducting block 603 is a second heat conducting block, for a green laser component, and the heat conducting block 603 is a third heat conducting block. The second heat conduction block and the third heat conduction block can be independent two parts, and can conduct heat for different laser components respectively, and can also be of a whole structure, so that the installation is convenient, and when the heat dissipation requirements of the laser components with two colors are the same, the temperature is also convenient to control.

Wherein the heat pipes are a plurality of heat pipes, and preferably, the number of the heat pipes corresponding to the blue and green laser components is the same. In this example, the heat pipes are straight heat pipes, and a plurality of heat pipes are provided, and a plurality of through holes are formed in the heat dissipation fins for inserting the plurality of heat pipes. The heat dissipation fins 601 are arranged close to the blue and green laser components, the heat pipes can be directly inserted into the heat dissipation fins without bending, and the straight heat pipes are beneficial to reducing transmission resistance in gas-liquid change inside the heat pipes and improving 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 trichromatic laser light source part. The light source emits three-color laser to provide high-quality illumination light beam, 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 required in the light source cavity to perform light combination, homogenization and other light treatment on laser beams in different directions.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A laser projection device is characterized by comprising a light source, a light machine and a lens; the source is used for providing light source illumination for the optical machine, and the lens is used for projection imaging;

the light source comprises a red laser component, a green laser component and a blue laser component, and red laser, green laser and blue laser are respectively emitted;

the red laser component is arranged close to the light source light outlet; the blue laser and the green laser are combined first and then combined with the red laser;

a static diffusion sheet is arranged in a light combining light path of the blue laser and the green laser, or the static diffusion sheet is respectively arranged for the blue laser and the green laser, and the blue laser and the green laser are diffused and then combined with the red laser beam;

a converging lens group is arranged at the light outlet of the light source and is used for converging the three-color laser beams after light combination to form small spots and then emergent from the light outlet of the light source;

the diffusion wheel is a rotary diffusion sheet and is positioned between the converging lens and the light receiving component and used for diffusing the three-color laser beams in a converging state;

The light receiving component is a light pipe or a fly eye lens and is used for homogenizing the diffused three-color laser beams.

2. The laser projection device of claim 1, wherein the stationary diffuser is used to diffuse blue and/or green laser light at an angle of 1 degree to 1 degree.

3. The laser projection device of claim 1, wherein the diffusion wheel has at least two sections; the red laser subarea divergence angle is the largest, the blue laser subarea divergence angle is the smallest, or the red laser subarea divergence angle is the largest, and the blue laser subarea divergence angle is the same as the green laser subarea divergence angle.

4. The laser projection device of, wherein the rotation period of the diffusion wheel is consistent with the primary light timing period of the light source.

5. The laser projection device of, wherein the focal point of the converging lens group is disposed at a light receiving opening of the light receiving element at the rear end.

6. The laser projection device as claimed in, wherein the red laser light and the blue laser light are different in polarization direction from the green laser light, and a half-wave plate is disposed in the optical path before the blue laser light and the green laser light are combined with the red laser light, and the half-wave plate is disposed on the light source housing inside a window opened for the laser assembly.

7. The laser projection device as claimed in claim 6, wherein the half-wave plate is provided in one piece in an optical path after the blue laser and the green laser are combined and before the red laser is combined, or the half-wave plate is provided in two pieces corresponding to the blue laser and the green laser, respectively.

8. The laser projection device of, wherein the red laser light and the blue laser light are different from each other in polarization direction, a half-wave plate corresponding to red wavelength is disposed before the red laser light and the blue laser light are combined, and the half-wave plate is disposed inside a window formed on the light source housing for the red laser assembly, or is disposed in the light source inner cavity and between the light source housing inside and a light combining lens corresponding to the red laser assembly.

9. The laser projection device of, wherein the red, blue, and green lasers are combined and then passed through a homogenizing element comprising a diffuser having a microstructure disposed on one side or on both sides.

10. The laser projection device as claimed in any one of claims 1, wherein the red laser assembly, the green laser assembly, and the blue laser assembly each include a laser and a PCB board disposed on an outer peripheral side of the laser, the laser including a plurality of light emitting chips packaged on a substrate.