CN111258165A - Laser projection device - Google Patents

Abstract

The application provides laser projection equipment, wherein a laser component used by the laser projection equipment emits a first color laser beam, a second color laser beam and a third color laser beam, the spot sizes of the three color laser beams are different, and the angles of the laser beams are different; after the light combining lens corresponding to the first light emitting area reflects the first color laser beam, the beam angle of the first color laser beam is increased; after the light combining lens corresponding to the second light emitting area reflects the second color laser beam, the beam angle of the second color laser beam is increased, so that the angle difference between the second color laser beam and the third color laser beam can be reduced, the spot size of the first color laser beam and the spot size of the second color laser beam are smaller than that of the third color laser beam, the color uniformity of the combined laser beams with different colors in the device is improved, and the display quality of a projection picture is improved.

Description

Laser projection device

Technical Field

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

Background

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

The lasers are classified into a blue laser, a red laser and a green laser according to the kind of light emission, and emit the blue laser, the red laser and the green laser, respectively. Among them, the blue laser is the earliest to be applied industrially, and the red and green lasers cannot be applied for a long time before being limited by the reason of power increase (such as less than 1W of light emitting power and low brightness), so most of the laser projection light sources appearing in the industry are mixed laser light sources of monochromatic laser (blue laser) and fluorescence, and the fluorescence is excited by the blue laser.

The solid-state laser is essentially a PN junction semiconductor, and is shown in a principle schematic diagram of a light emitting chip of the laser shown in FIG. 1. an active layer (also called an active region) is arranged between a P-type semiconductor and an N-type semiconductor, and laser beams with different wavelengths are emitted from a front cavity surface due to oscillation of a resonant cavity in the active region. specifically, as shown in FIG. 2-1, the laser beams are emitted from light emitting points in radial beams, α shown in the figure respectively indicate divergence angles in slow axis and fast axis directions, and it can be seen from the figure that the fast axis diverges faster, the angle is larger, the slow axis diverges relatively slower, the angle is smaller, and thus the shape of the laser beams is elliptical.

The blue laser and the green laser can be generated by using gallium arsenide luminescent materials, and the red laser is generated by using gallium nitride luminescent materials. Since the light emitting mechanism of the light emitting material is different, the light emitting efficiency of the red laser is low and the thermal conversion rate is high in the process of generating each color of laser. The light emitting efficiency of the blue laser and the green laser is relatively high, and the corresponding chip can meet the light emitting requirement by arranging a light emitting point. In order to meet the requirement of the light emitting power, as shown in fig. 2-2, the light emitting power of the red laser chip needs to be increased by arranging a plurality of light emitting points, which also causes the size of the red laser beam to be relatively large, and simultaneously, because of the difference of the light emitting mechanisms of the light emitting materials, the divergence speeds of the fast and slow axes of the red laser are both greater than the divergence degrees of the blue laser and the green laser.

However, the difference between the red laser and the blue and green lasers, such as those described above, causes some problems of low quality and efficiency of three-color combined light when applied to a three-color laser as a light source, which causes degradation of quality of a projection picture in a laser projection apparatus.

Disclosure of Invention

The application provides a laser projection device, which can solve the problem.

To achieve the above technical object, the present application provides a laser projection apparatus including a light source for providing an illumination beam; the optical machine is used for modulating the illumination light beam; the lens is used for receiving the modulated illumination light beam to perform projection imaging;

wherein the light source includes: the laser assembly is provided with a first light emitting area, a second light emitting area and a third light emitting area and respectively emits a first color laser beam, a second color laser beam and a third color laser beam, wherein the spot areas of the emitted first color laser beam and the second color laser beam are smaller than the spot area of the third color laser beam;

the light combining lens group is provided with a plurality of light combining lenses, is respectively arranged corresponding to the first light emitting area, the second light emitting area and the third light emitting area, and is used for emitting the laser beams emitted by the light emitting areas to the light source light outlet; after the light combining lens corresponding to the first light emitting area reflects the first color laser beam, the beam angle of the first color laser beam is increased; after the light combining lens corresponding to the second light emitting area reflects the second color laser beam, the beam angle of the second color laser beam is increased.

In the laser projection equipment technical scheme that this application provided, the laser instrument subassembly that sends different colours has been used, the beam angle of the laser beam of the different colours that sends is different, increase through carrying out the beam angle to the laser beam of light beam depth of parallelism preferred, expand the beam in other words, the beam angle with the laser beam of light beam depth of parallelism poor slightly reduces the difference, after the laser beam of different colours combines the beam, thereby make first colour laser beam and second colour laser beam and third colour laser beam's beam angle approach unanimous or be close to, after the laser beam of different colours combines the beam, the coincidence degree of facula improves, thereby the colour homogeneity of the light spot that combines has been improved, can improve the display quality of projection picture.

Drawings

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

FIG. 1 is a schematic diagram of a laser light emitting chip;

FIG. 2-1 is a schematic diagram of the laser emitting chip emitting light beams;

FIG. 2-2 is a schematic diagram of a red laser light-emitting chip;

fig. 3 is a schematic structural diagram of a laser projection apparatus according to an embodiment of the present disclosure;

FIG. 4-1 is a schematic diagram of an optical engine according to an embodiment of the present disclosure;

FIG. 4-2 is an exploded view of an optical engine according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of an optical principle of a laser projection apparatus according to an embodiment of the present disclosure;

FIG. 6-1 is a schematic view of a light source according to an embodiment of the present disclosure;

FIG. 6-2 is a cross-sectional view of a light source structure of FIG. 6-1;

FIG. 7-1 is a schematic view of an internal structure of a light source according to an embodiment of the present disclosure;

FIG. 7-2 is a schematic view of an internal structure of another light source provided in the embodiments of the present application;

7-3 are schematic internal structural diagrams of still another light source provided in the embodiments of the present application;

FIGS. 7-4 are schematic views of an internal structure of another light source according to an embodiment of the present disclosure;

FIG. 8-1 is a schematic diagram of the laser structure of FIG. 6;

FIG. 8-2 is a schematic diagram of the laser assembly of FIG. 6;

FIG. 9-1 is a schematic view of a light source configuration;

FIG. 9-2 is a distribution of light spots of the illumination beam output by the light source of FIG. 9-1;

fig. 10 is a schematic diagram of the polarization of laser polarized light.

Detailed Description

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

Fig. 3 shows a schematic structural diagram of a laser projection device, and the structure and operation of the laser projection device according to the embodiment will be described first according to the laser projection device example shown in fig. 3.

The laser projection apparatus 10 includes a whole casing 011 and a base 012, the whole casing 011 and the base 012 form an accommodating space, and in the accommodating space, the laser projection apparatus further includes a light source 100, an optical engine 200, and a lens 300, which are assembled on the base 012, and these three parts form an optical engine part and are connected in sequence along a light beam propagation direction. Each of the three major portions has a corresponding housing to enclose the optical components and to provide a hermetic seal or seal to each optical portion.

The accommodating space formed by the complete machine shell 011 and the base 012 also comprises a plurality of circuit boards 400, the circuit boards 400 are parallel to each other, and the inner side of the complete machine shell 011 is vertically arranged on the base 012.

In one embodiment, see fig. 3, wherein the optical engine 200 and the lens 300 are connected and disposed along a first direction of the whole machine, for example, the first direction may be a width direction of the whole machine, or according to a use mode, the first direction is opposite to a direction viewed by a user, and a connection direction of the light source 100 and the optical engine 200 is perpendicular to the first direction, so that an optical engine portion composed of the light source 100, the optical engine 200, and the lens 300 is connected in an "L" shape. The optical machine is positioned at the corner position of the L shape. So that the optical axis makes a 90 degree turn, and the length of the optical path in one direction is compressed.

Referring to fig. 3, the laser projection apparatus 10 further includes a plurality of circuit boards 400, the plurality of circuit boards 400 being disposed vertically with respect to the bottom 102 and along the inside of the whole housing 011. In the drawings, only a part of the whole casing 101 is schematically represented. Specifically, the circuit boards 400 are arranged in parallel to each other and disposed next to the inner side of the whole casing 101, and generally, the whole casing 101 is a cover body including a top cover, and the casing shown herein may refer to a casing portion around the main body of the device.

The plurality of circuit boards 400 include a power supply board, also referred to as a power supply board, for providing power to a plurality of modules of the device; the display board card is mainly used for controlling the imaging of the projection system, and in the embodiment, the display board card is a DLP system, such as the generation of a DMD chip signal, the output of a light source time sequence signal and a PWM brightness dimming signal, and the like; the signal transmission board card, also called TV board, is mainly used for decoding video signals to form image signals, and transmitting the image signals to the display board card for further image processing.

Fig. 5 is a schematic diagram of the optical path of the laser projection apparatus. As shown in fig. 5, the light beam output from the light source 100 is incident into the optical engine 200, and the optical engine 200 further emits the light beam into the lens 300. In one embodiment, the light source 100 is a three-color laser light source capable of outputting red, green and blue laser lights. The light source 100 further includes a plurality of optical lenses for combining and condensing the laser beams. Since the laser itself has strong coherence, in order to improve the speckle problem caused by laser projection, a speckle-dispersing component, such as a moving diffusion sheet, may be further disposed in the light path from the light source 100 to the optical machine 200, and after the moving diffusion sheet diffuses the light beam, the divergence angle of the light beam may be increased, which is beneficial to improving the speckle phenomenon. The moving diffusion sheet may be disposed in the light source 100 or in the light engine 200.

The light beam emitted from the light source 100 is incident to the optical engine 200, and usually a homogenizing component, such as a light pipe, is located at the front end of the optical engine 200 for receiving the illumination light beam of the light source, and has the functions of mixing and homogenizing, and the outlet of the light pipe is rectangular, and has a shaping effect on the light spot. The optical engine 200 further includes a plurality of lens groups, and the TIR or RTIR prism is used to form an illumination light path, and to inject the light beam to the light valve, which is a key core device, and to inject the light beam modulated by the light valve into the lens group of the lens 300 for imaging.

The Light valve may include a variety of structures such as LCOS, LCD or DMD, and in this example, a dlp (digital Light processing) projection structure is used, and the Light valve is referred to as a DMD chip or a digital micromirror array. Before the light beam of the light source 100 reaches the light valve DMD, the light path of the light machine is shaped to make the illumination light beam conform to the illumination size and the incident angle required by the DMD. The DMD surface includes thousands of tiny mirrors, each of which can be individually driven to deflect, such as plus or minus 12 degrees or plus or minus 17 degrees in a DMD chip provided by TI. The light reflected by the positive deflection angle is called ON light, the light reflected by the negative deflection angle is called OFF light, and the OFF light is ineffective light and generally hits the shell or is absorbed by a light absorption device. The ON light is an effective light beam that is irradiated by the illumination light beam received by a tiny mirror ON the surface of the DMD light valve and is incident ON the lens part 300 through a positive deflection angle, and is used for projection imaging. The quality of the illumination beam emitted from the light source 100 directly affects the quality of the beam irradiated onto the surface of the light valve DMD, so that the beam is projected and imaged through the lens 300 and then reflected on a projection picture.

In this example, the lens 300 is an ultra-short-focus projection lens, and a light beam modulated by a light valve enters the lens and finally exits in an oblique direction, which is different from a light exit mode in which an optical axis of a projection light beam is located at a perpendicular line in a projection picture in a conventional long-focus projection, the ultra-short-focus projection lens usually has an offset of 120% to 150% relative to the projection picture, the projection mode has a smaller throw ratio (which can be understood as a ratio of a distance from a projection host to a projection screen to a size of a diagonal line of the projection picture), for example, about 0.2 or even smaller, so that the projection device and the projection screen can be closer to each other, and thus the projection device is suitable for home use, but the light exit mode also determines that the light beam has higher uniformity, otherwise, the luminance or chromaticity non-uniformity of the projection picture is more obvious.

In this example, when a DMD light valve assembly is used, the light source 100 can output three primary colors in a time sequence, and the human eye cannot distinguish the colors of light at a certain time according to the principle of three-color mixing, and still perceives mixed white light. When a plurality of light valve components, such as three DMD or three LCD liquid crystal light valves, are used, the three primary colors of light in the light source 100 can be simultaneously lit to output white light.

It should be noted that, in order to enhance the brightness of the light source, sometimes a yellow primary color is added on the basis of the three primary colors, and the yellow primary color light can be generated by overlapping the red light and the green light, so that, when four colors are output in time sequence by controlling the three lasers of red, green and blue, there may be a period in which two primary colors are output simultaneously, that is, the red and the green have an overlapping period for controlling the output of the yellow primary color.

Fig. 4-1 is a schematic diagram of an optical engine of the laser projection device of fig. 3. Specifically, the device comprises a light source 100, an optical engine 200 and a lens 300. The three are connected together through a structural part, and the light path is sealed in the shell structure.

Fig. 4-2 shows an exploded view of an optical engine configuration. Illustratively, the light beam emitted from the light source 100 enters the light bar 210 after passing through a diffusion wheel 140, and the diffusion wheel 140 may perform angular divergence on the laser beam through the diffusion sheet, so as to form diversity of divergence angles, thereby playing a role of speckle elimination. The light bar 210 is a homogenizing component having a rectangular light incident surface and a light emergent surface, and after entering the light bar, the laser beam is reflected for multiple times by using the total reflection principle, and the energy distribution of the light spot can be homogenized, and the divergence angle of the laser beam is constrained by the arrangement of the areas of the light emergent surface and the light incident surface. The light-emitting surface of the light bar 210 and the light-entering surface of the light valve 220 are conjugate to each other, so it can be understood that the light-emitting surface of the light bar is an object plane, and the light-entering surface of the light valve is an image plane. The light beams of the light bar 210 entering the light surface and exiting the light surface satisfy the lagrange's invariant law, that is, the integral value of the incident angle and area of the light beam entering the light surface is equal to the integral value of the incident angle and area of the exiting the light surface, so that the incident angle and the size of the light spot of the light bar entering the light surface determine the light beam index of the light beam in the rear light path.

Fig. 6-1 shows a light source configuration in the laser projection device of fig. 3. As shown in fig. 6-1, the light source unit 100 of the laser projection apparatus 10 includes a housing 150 and a laser module 110, wherein the light source unit 100 is a three-color laser light source, and a three-color laser beam exits from an opening 152 of the light source unit 100.

Fig. 6-2 is a cross-sectional schematic view of the light source structure of fig. 6-1. The light source housing 150 has an accommodating cavity 151, the laser assembly 110 and the light combining lens assembly 120 are both at least partially accommodated in the accommodating cavity 151, the accommodating cavity 151 has an opening 152 along the light exit direction of the light source, and the opening is provided with a focusing lens 112 for converging the light combining beam.

In this example, the laser assembly 110 is a laser that can emit laser light of three colors. An MCL-type laser as shown in fig. 8-1 includes a first light emitting region 1101, a second light emitting region 1102, and a third light emitting region 1103.

The first light emitting region can emit blue laser, the second light emitting region can emit green laser, and the third light emitting region can emit red laser.

The three light emitting regions are located on the same laser package, that is, the light emitting chips of the three-color laser are arranged in an array and packaged in a module, for example, the MCL type laser used in this example is a light emitting array of 4 × 5. The laser assembly includes a substrate 1110, a plurality of light emitting chips are packaged on the substrate 1110, and a collimating lens group 1112 is further disposed at a light emitting surface of the laser assembly. The light emitting surface of the laser component is provided with a plurality of light emitting areas, and the colors of light beams emitted by different light emitting areas are different; one of the rows emits green light, one emits blue light, and the remaining two rows emit red light. Above-mentioned laser instrument subassembly is in the same place the encapsulation of three-colour luminescence chip, and the volume is less, does benefit to the volume that reduces light source device.

It should be noted that the laser module in this example is not limited to the 4X5 array, but may be arranged in other arrays, such as 3X5 array or 2X7 array, as long as it can emit three-color laser beams.

As shown in fig. 8-2, the circuit board is a flat structure, two sides of the laser have pins 1111, the pins 1111 are respectively welded or inserted onto the circuit boards 1113a and 1113b that are almost parallel to the plane of the laser, wherein the pins 1113a and 1113b may be integrally formed and surround the outer side of the laser module substrate 1110, or the pins 1113a and 1113b may also be two independent circuit boards, which surround the laser module 110.

As shown in fig. 6-1 and 6-2, the laser assembly 110 is fixed to the housing 150 by screws, and emits three-color laser beams into the accommodating cavity inside the light source housing, and the three-color laser beams face the light emitting surface of the laser assembly, and the light combining lens assembly 120 is disposed in the accommodating cavity inside the housing.

The light combining lens assembly 120 is provided with a plurality of light combining lenses corresponding to each light emitting region of the laser assembly 110, and each light combining lens corresponds to a different light emitting region and is used for combining laser beams of different light emitting regions.

The light combining mirror assembly 120 combines the light beams of different areas to output from the light outlet of the laser light source. As shown in fig. 6-2, the light combining lens group 120 includes three light combining lenses 1201, 1202, 1203 sequentially disposed on the optical transmission path of the laser. Different light combining lenses are arranged on an emergent light path of the light-emitting area which emits the light beams with the corresponding colors, the corresponding light combining lenses can reflect the light beams corresponding to the light-emitting area, the reflected light beams all follow the direction of the light-emitting port of the laser light source, and the light beams with the colors are converged to form white light.

Specifically, the first light combining lens 1201 is configured to receive a light beam emitted from the first light emitting area, the second light combining lens 1202 is configured to receive a light beam emitted from the second light emitting area, and the third light combining lens 1203 is configured to receive a light beam emitted from the third light emitting area.

Fig. 7-1 shows a schematic diagram of a light source light path, where a plurality of light combining lenses 1201, 1202, 1203 are all configured to reflect light beams emitted from corresponding light emitting areas to a light emitting direction of the light source, the plurality of light combining lenses are all sequentially arranged toward the light emitting direction of the laser light source, and at least one light combining lens can transmit light beams of corresponding colors from other light emitting areas, combine the light beams with the light beams reflected therefrom, and emit the light beams along the light emitting direction of the laser light source. The laser device comprises a first color laser beam, a second color laser beam, a third color laser beam and a fourth color laser beam, wherein the spot areas of the first color laser beam and the second color laser beam are both smaller than the spot area of the third color laser beam, when the first color and the second color are blue and green, and the third color is red, the beam angles of the first color laser beam and the second color laser beam are different from the angle of the third color laser beam, and specifically, the beam angles of the first color laser beam and the second color laser beam are both smaller than the beam angle of the third color laser beam.

Specifically, included angles between light receiving surfaces of the first light combining lens 1201, the second light combining lens 1202 and the third light combining lens 1203 and green laser beams, blue laser beams and red laser beams emitted by a light emitting region of the laser assembly can be set to be 45 ° ± 2 °, wherein the first light combining lens 1201 is a reflecting lens, and the second light combining lens 1202 and the third light combining lens 1203 are dichroic sheets. The first light combining lens 1201, the second light combining lens 1202, and the third light combining lens 1203 are disposed in parallel to each other.

The first light emitting area 1101 emits first color laser light, and the first light combining lens 1201 is a reflecting mirror for reflecting the first color laser light beam. In a specific implementation, the laser beam of the first color is collimated by the collimating lens group when being emitted from the laser assembly 110 and can be approximately regarded as a parallel beam, after the approximately parallel beam is reflected by the first light combining lens 1201, the beam divergence angle is increased by 2 ° to 8 °, and the light spot of the laser beam of the first color is located in the range of the light spot equal to that of the laser beam of the third color.

And the second light-emitting region 1102 emits the second color laser light, and the second light-combining lens 1202 is configured to reflect the second color laser light beam and transmit the first color laser light beam, and is a dichroic mirror. In a specific implementation, the laser beam of the second color is collimated by the collimating lens group when being emitted from the laser component 110, and can also be regarded as a parallel beam approximately, after being reflected by the first light combining lens 1202, the angle of the parallel beam is increased by 2 ° to 8 °, and the light spot of the laser beam of the second color is located in the range of the light spot equal to that of the laser beam of the third color.

And, as shown in fig. 7-1, the third light emitting region 1103 emits the laser light of the third color, and the third light combining lens 1203 is configured to reflect the laser light beam of the third color and transmit the laser light beams of the first color and the second color. The third light combining lens 1203 is a dichroic mirror, a reflection surface and a transmission surface of the third light combining lens 1203 are both flat surfaces, the laser beam of the third color is reflected by the third light combining lens 1202 and then exits toward the light exit of the light source, and the laser beams of the first color and the second color also exit toward the light exit of the light source after being transmitted by the third light combining lens 1303.

In the MCL package laser of this example, the third color laser beam is a red laser beam, and is in two rows or two columns, and the third light combining lens is configured to receive the two rows of red laser beams, and has a size larger than the first light combining lens and the second light combining lens, so that all the beams transmitted and reflected by the second light combining lens can be received.

In this example, the third light exiting region 1103 emits two laser beams of the third color, the first light exiting region 1101 emits one laser beam of the first color, and the second light exiting region 1102 emits one laser beam of the second color. When the three color laser beams irradiate the third light combining lens 1203, the positions where the first color laser beam and the second color laser beam are incident on the third light combining lens 1203 are preferably located between two third color laser beams.

In the light source shown in fig. 7-1, the first color is blue, the second color is green, and the third color is red, wherein the size of the red laser emitting chip is larger than that of the blue laser and the green laser emitting chips, the fast-slow axis divergence angle range of the red laser is larger than that of the blue laser and the green laser, for example, the size of the red laser emitting chip is about 300 μm, the size of the blue laser emitting chip and that of the green laser emitting chip are about 70 μm, the slow axis divergence angle of the red laser is about 10 to 15 degrees, the fast axis divergence angle is about 30 degrees, the fast axis divergence angle of the blue laser and that of the green laser is about 7 to 10 degrees, the collimating lens group of the laser assembly 110 is an integrated lens combination, and the collimating power of each lens can be considered to be the same, while the divergence angles of the three colors of laser light are different. Therefore, when three laser beams with different divergences are collimated by the same collimating lens, the collimating effect is different, for example, the collimating effect of the blue laser and the green laser is similar, and the collimated beam parallelism is smaller than that of the blue laser and the green laser because the divergence degree of the red laser is larger. Thus, the beam angle of the third color laser beam is larger than the angles of the first and second color laser beams. And the third color laser beam is two laser beams, so that the spot area of the third color laser beam is larger. By positioning the positions of the second color laser beam and the first color laser beam entering the third light combining lens 1203 between the two third color laser beams, the spot size of the combined light beam is only equivalent to the spot size of the original third color laser beam, and the increase of the size of the combined light beam due to the combination of the light beams with the spot sizes of the three colors is avoided.

And, in the light source shown in fig. 7-1, the first light combining lens 1201 has a convex reflective surface, and the second light combining lens 1202 also has a convex reflective surface, so that the beam angles of the first color laser beam and the second color laser beam after being reflected by the convex surface can be increased, respectively, and thus, the beam angles of the first color laser beam and the second color laser beam after being reflected by the convex surface are increased to be closer to the third color laser beam, so that the uniformity of the light combining spot is better after the laser beams of the three colors are combined.

A comparative example is given in fig. 9-1 and 9-2. In practice, as shown in fig. 9-1, when the first light combining mirror 1201 and the second light combining mirror 1201 both use a planar reflection surface for reflection, the reflected beam angles of the first color laser beam and the second color laser beam are both similar to the angle of the light emitted from the light emitting surface of the laser module 110. When the laser beams of the three colors are combined by the third light combining lens 1203, by analyzing the light spots on the light incident surface of the light bar, as shown in fig. 9-2, the distribution of the light spots measured on the light incident surface of the light bar can show a more obvious color demarcation phenomenon between the inner circle and the outer circle, for example, the converged light spots are approximately circular, the outermost circle is red, and the light spots are sequentially inward diaphragms of different concentric circles such as purple, blue and the like. The above-described graphical phenomenon shows that the laser beams of three colors have a phenomenon of uneven distribution of the combined color.

In this application embodiment, through setting up the light reflection plane of the light combination lens that first colour laser beam and second colour laser beam correspond to convex surface reflecting surface, can increase the beam angle of first colour laser beam and second colour laser beam, make the beam angle with the great third colour laser beam of beam angle more close, and the facula of first colour laser beam and second colour laser beam all superposes again within the spot size of third colour laser beam, thereby, the colour demarcation phenomenon of the tricolor laser facula after the combination has been alleviated, the coincidence degree of the beam spot improves, colour homogeneity is better, luminance is also more even. The light source in the above example may provide a high quality combined light beam.

And, fig. 7-2 provides another example of a light source, based on the example of a light source provided in fig. 7-1.

In this example, the first color laser beam, the second color laser beam, and the third color laser beam are all linearly polarized light.

The polarization directions of the first color laser beams and the second color laser beams are the same and different from the polarization direction of the third color laser beams. In one embodiment, the first color is green, the second color is blue, the third color is red, the red laser is P-polarized light, and the blue laser and the green laser are both S-polarized light, such that the polarization directions are 90 degrees different.

In this example, the blue laser light exit region 1102 and the green laser light exit region 1101 are disposed adjacently. The blue laser and the green laser emitted from the laser device both penetrate through the phase retardation plate 1304 and then enter the light combining lens assembly 120.

The retardation plate 1304 is disposed facing the blue laser emitting area and the green laser emitting area, and is located in the output light path of the blue light and the green light and before the incident light enters the light combining lens assembly 120.

The phase retarder is a half-wave plate, also called λ As wave plate, which affects the degree of phase change of the transmitted light beam by the thickness of the crystal growth, and in this example, the phase retarder changes the phase of the light beam corresponding to the color wavelength by π, i.e., 180 degrees, and rotates the polarization direction by 90 degrees, such as changing P light into S light or changing S light into P light.

After passing through the half-wave plate, the light originally having the P polarization direction becomes the light having the S polarization direction, and the two polarization directions are perpendicular to each other as shown in fig. 10.

The phase retarder 1304 is fixed inside the light source housing 150 by clamping and fixing, and does not block the light path.

The phase retarder is specifically a half-wave plate, and is disposed between the light emitting surface 1101 of the green light emitting region and the light emitting surface 1102 of the blue light emitting region of the laser, and the first light combining lens 1201 and the second light combining lens 1202.

Specifically, the half-wave plate is arranged in parallel to the light emitting surfaces of the green light emitting region 1101 and the blue light emitting region 1102 of the laser, and the size of the half-wave plate is consistent with the size of the light emitting surfaces of the green light emitting region 1101 and the blue light emitting region 1102, so that the light beams of all two colors can be received.

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

And, as shown in fig. 6-1, a diffusion part 140 is further provided in the light output path of the light source, the diffusion part 140 is provided on the light output path of the focusing lens, and the light beam diffused by the diffusion part 140 is incident to a light homogenizing member (not shown). The diffuser 140 may be a rotating diffuser plate forming a diffuser wheel structure. Through rotating diffusion, speckle can be eliminated on the light beam, so that the light beam quality is improved, and the speckle effect of a projected image is reduced; the diffused light beam can enter a light homogenizing component, specifically, the light homogenizing component can be a light rod or a compound eye lens group.

In one embodiment, the half-wave plate 1304 is a single plate, and preferably, the half-wave plate is set to correspond to the wavelength of the green laser beam, so that the polarization direction of the green laser beam is rotated by 90 degrees after passing through the half-wave plate, and the original S light is changed into the P light. After the blue laser light passes through the half-wave plate, the wavelength of the half-wave plate is not set corresponding to the blue wavelength, so the polarization direction of the blue laser light is deflected not 90 degrees, but is close to the P polarization direction. Of course, the wavelength of the blue laser beam may be selected so that the polarization direction of the blue laser beam is rotated by 90 degrees after passing through the half-wave plate, the original S light is changed into the P light, and the polarization direction of the green laser beam is changed by approximately 90 degrees.

And, in one implementation, as shown in the light source of fig. 7-3, the phase retarders are two pieces, and may be specifically half-wave plates 1301, 1302, respectively, which may be set for the wavelengths of the green laser light and the blue laser light, respectively, so that the polarization directions of both the green laser light and the blue laser light may be changed by 90 degrees to become P light. Or the half-wave plate is one piece, but is divided into two coating areas, and the two coating areas are respectively arranged aiming at the green laser light-emitting area and the blue laser light-emitting area, so that the half-wave plate is equivalent to the half-wave plate which is respectively provided with corresponding wavelengths for the blue laser and the green laser.

When the half-wave plate is two or two coating areas, the half-wave plate is respectively disposed in the output light paths of the blue laser and the green laser, specifically, the half-wave plate 1301 is disposed in the light path of the green laser incident on the first light combining lens 1201, and the half-wave plate 1302 is disposed in the light path of the color laser incident on the second light combining lens 1202. When the half-wave plates are respectively arranged for the light beams of one color, compared with a mode of performing phase retardation on the blue laser and the green laser by sharing the same half-wave plate, the method can perform more accurate phase retardation on the corresponding wavelength, so that the green polarized light and the blue polarized light in the P polarization direction close to the theoretical value can be obtained.

The same optical lens has the same transmittance and reflectance for P light and S light of different wavelengths for different wavelengths. The optical lens includes not only the aforementioned beam shaping component-focusing lens, but also a lens group in the illumination optical path in the optical engine part, and a refractive lens group in the lens part. Therefore, when the light beam emitted from the laser light source passes through the whole projection optical system, the difference in transmission contrast is a result of superposition of the whole system, and is more obvious.

Before the half-wave plate is added, especially when the primary light is P light and S light polarized light, the selective transmission phenomenon of the optical lens of the optical system to the P light and the S light is obvious. This causes a problem of local color unevenness of the projection picture, thereby degrading the quality of the projection picture.

In the embodiment, when the half-wave plates are arranged in the light emitting paths of the blue laser and the green laser, especially when the half-wave plates with corresponding wavelengths are respectively arranged for the blue laser and the green laser, the same deflection angle can be changed for the polarization directions of the blue laser and the green laser, in the example, the polarization direction of the S light is changed into the polarization direction of the P light, and the polarization direction of the P light 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 set of optical imaging system and are reflected into human eyes through a projection screen, the transmittance of the optical lens of the optical system is equivalent to that of the red laser which is the P light, the uniformity of the light processing process is close, the uniformity of the polarity is performed before the three-color laser is combined, and the difference of the transmittance and the reflectance of the light beams caused by the different polarities can be reduced when the three-color laser is combined, and because the beam angles of the blue laser and the green laser are increased, the beam angles are closer to the beam angles of the red laser, so that the uniformity of the beam combining spots of the lasers with different colors is better, and the difference of selective treatment of the optical lens can be eliminated due to the consistency of the polarities. On one hand, the light beam in the system has lower light loss, on the other hand, the color uniformity of the light combining facula is better, after the light beam is modulated by the light valve and projected by the lens, the uniformity of the chromaticity and the brightness of the displayed projection picture is improved, and the display quality of the projection picture is higher.

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

And, as a modification of the above embodiment, in this example, the blue laser and the green laser are combined first and then combined with the red laser, and at this time, a phase retarder, specifically a half-wave plate, may also be provided in the optical path of the blue laser and the green laser before being combined with the red laser. Specifically, the half-wave plate 1304 may be disposed between the second light combining lens 1202 and the third light combining lens 1203, and may transmit the combined blue laser beam and green laser beam emitted from the second light combining lens 1202. At this time, the half-wave plate 1304 is not coated in a divided manner, but is coated corresponding to a wavelength of one color.

And, as another light source example shown in fig. 7-4, unlike the previous embodiment in this example, a phase retarder 1303 is disposed in the light output path of the red laser beam before being combined with the blue and green laser beams. For example, between the red laser emitting region 1103 and the third light combining lens 1203.

The half-wave plate 1303 is set corresponding to the wavelength of the red laser light, and similarly, the polarization direction of the red laser light can be rotated by 90 degrees by the half-wave plate 130R, and the red laser light is changed from P-polarized light to S-polarized light. Thus, the polarization directions of the blue laser beam, the green laser beam, and the red laser beam are also aligned.

In the above embodiments of the present application, laser assemblies emitting lasers of three colors are applied, and the lasers of three colors are arranged in rows or columns. The wavelength of the first color and the wavelength of the second color are both less than the wavelength of the third color. The first color laser and the second color laser are arranged adjacently, the first color laser beam and the second color laser beam are reflected and then combined with the third color laser beam, the first color laser beam and the second color laser beam are reflected by the convex reflector, the beam angle is increased, the difference of the beam angle with the third color laser beam is reduced, the spot size of the first color laser beam and the second color laser beam which are originally sent by the laser component is smaller than that of the third color laser beam, after the three-color laser is combined by the convex reflector, the coincidence degree of the light spots of the combined light is improved, the phenomenon of light spot aperture boundary is reduced or eliminated, the color uniformity is improved, meanwhile, the brightness uniformity can also be correspondingly improved, and the display quality of a projection picture is also improved.

Further, in the above example, the polarization characteristics of the laser beams of different colors are different, which affects the processing efficiency of the beams in the optical lens, and a phenomenon of local chromaticity non-uniformity is also easily generated, and this phenomenon is more prominent for the ultra-short focus projection apparatus. The half-wave plate is arranged in the light path before the three-color laser beams are combined to form a beam, so that the polarity of a certain type of laser beams is changed, the polarization polarities of the three-color laser beams with different colors are consistent, and then the light is combined, so that the light loss of a light spot after the light is combined is low, and the color uniformity of the light spot can be ensured.

In summary, in the one or more examples of the laser projection apparatus provided in the present application, the laser beams of different colors have different beam angles, and the increase of the beam angle is performed on the laser beam with better beam parallelism, which is equivalent to performing beam expansion, so that the difference between the beam angle of the laser beam with slightly worse beam parallelism and the beam angle of the laser beam with better beam parallelism is reduced, and thus after the laser beams of different colors are combined and combined, the coincidence degree of the combined light spot is improved, the color uniformity is better, and the display quality of the projection image can be improved.

Meanwhile, in the example of the one or more laser projection devices provided by the application, the polarization polarities of the laser beams with different colors are different, and the polarization polarities of the laser beams with three colors are consistent by arranging the half-wave plate in the path before the laser beams with different colors are combined, so that the polarization polarities of the laser beams with three colors are consistent, the consistency of the light processing efficiency of the light spots after light combination is high, the brightness loss is reduced, the uniformity improvement of the color and the brightness of the light combination light spots is facilitated, and the display quality of a projection picture is improved.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims (12)

1. A laser projection device comprising a light source for providing an illumination beam; an optical machine for modulating the illumination beam; the lens is used for receiving the modulated illumination light beam to perform projection imaging; the light source includes:

the laser assembly is provided with a first light emitting area, a second light emitting area and a third light emitting area and respectively emits a first color laser beam, a second color laser beam and a third color laser beam, wherein the spot areas of the emitted first color laser beam and the second color laser beam are smaller than the spot area of the third color laser beam;

a light combining lens group having a plurality of light combining lenses, respectively corresponding to the first light emitting area, the second light emitting area and the third light emitting area, for emitting the laser beam emitted from the light emitting areas to a light source light outlet;

after the light combining lens corresponding to the first light emitting area reflects the first color laser beam, the beam angle of the first color laser beam is increased;

and after the light combining lens corresponding to the second light emitting area reflects the second color laser beam, the beam angle of the second color laser beam is increased.

2. The laser projection device of claim 1, wherein the first light exit region, the second light exit region, and the third light exit region are located on the same laser assembly.

3. The laser projection apparatus according to claim 1, wherein the light combining lens group includes a first light combining lens, a second light combining lens and a third light combining lens, which are respectively disposed corresponding to the first light emitting area, the second light emitting area and the third light emitting area;

the first light combining lens is used for reflecting the first color laser beam to the second light combining lens; the second light combining lens is used for transmitting the first color laser beam and reflecting the second color laser beam to the third light combining lens; the third light-combining lens is used for transmitting the first color laser beams and the second color laser beams and reflecting the third color laser beams to a light source light outlet.

4. The laser projection device of claim 1 or 3, wherein the first light combining lens is a convex reflector; and/or the second light combining lens is a dichroic mirror with a convex reflecting surface.

5. The laser projection device of claim 4, wherein the first light combining lens is configured to increase the angle of the first color laser beam by 2 ° to 8 °.

6. The laser projection device of claim 4, wherein the second light combining lens is configured to increase the angle of the second color laser beam by 2 ° to 8 °.

7. The laser projection apparatus according to claim 1, wherein the first light exit region, the second light exit region, and the third light exit region are disposed adjacent to each other in this order, and an area of each of the third light exit regions is larger than an area of each of the first light exit region and the second light exit region.

8. The laser projection apparatus according to claim 1, wherein the positions where the first color laser beam and the second color laser beam are incident on the third light combining lens are located between two third color laser beams.

9. The laser projection apparatus according to claim 4, wherein the first color laser beam further passes through a first phase retarder before entering the first light combining lens, the second color laser beam further passes through a second phase retarder before entering the second light combining lens, and the third color laser beam does not pass through the first phase retarder and the second phase retarder.

10. The laser projection apparatus of claim 9, wherein the first phase retarder is a half-wave plate corresponding to a wavelength setting of the first color laser light, and the second phase retarder is a half-wave plate corresponding to a wavelength setting of the second color laser light.

11. The laser projection apparatus of claim 4, wherein the third color laser beam further passes through a third phase retarder before entering the third light combining lens, and neither the first color laser beam nor the second color laser beam passes through the third phase retarder.

12. The laser projection device of claim 11, wherein the third phase retarder is a half-wave plate corresponding to the third color laser wavelength setting.

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