CN121325493A - A projection device - Google Patents
A projection deviceInfo
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- CN121325493A CN121325493A CN202410939717.6A CN202410939717A CN121325493A CN 121325493 A CN121325493 A CN 121325493A CN 202410939717 A CN202410939717 A CN 202410939717A CN 121325493 A CN121325493 A CN 121325493A
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Abstract
本发明公开了一种投影设备，包括激光光源，以及沿着激光光源的出光路径上依次设置的衍射光学元件、倍率透镜、匀光元件、全反射棱镜和显示元件。激光光源包括三类出光区域和与三类出光区域对应设置的三个衍射光学元件，三类出光区域出射的激光的波长不同，每个出光区域出射的激光光束经衍射光学元件衍射后入射到显示元件时形成的光斑为矩形光斑，该矩形光斑与显示元件的有效区域相匹配，矩形光斑的长边方向与出光区域出射的激光光束的慢轴方向平行。由此可以使激光器、衍射光学元件和显示元件三者的光学扩展量更加匹配，不仅可以提高衍射光学元件的衍射效率，还能够提高光学系统的光效。
This invention discloses a projection device, including a laser source and a diffractive optical element, a magnification lens, a homogenizing element, a total internal reflection prism, and a display element arranged sequentially along the light emission path of the laser source. The laser source includes three types of emission regions and three diffractive optical elements corresponding to these regions. The laser beams emitted from the three emission regions have different wavelengths. When the laser beam emitted from each emission region is diffracted by the diffractive optical elements and incident on the display element, it forms a rectangular spot. This rectangular spot matches the effective area of the display element, and the long side of the rectangular spot is parallel to the slow axis of the laser beam emitted from the emission region. This allows for a better match between the optical spread of the laser, the diffractive optical element, and the display element, improving not only the diffraction efficiency of the diffractive optical element but also the luminous efficiency of the optical system.
Description
Technical Field
The present disclosure relates to projection technology, and in particular, to a projection device.
Background
The laser projection display technology is also called a laser projection technology or a laser display technology, and is a technology for performing projection display using laser as a light source. The laser projection can truly reproduce the rich and gorgeous colors of the objective world and provide more shocking expressive force. The color gamut coverage rate can reach more than 90% of the color space which can be identified by human eyes, and is more than twice of the color gamut coverage rate of the traditional display.
At present, a laser projection system is generally provided with an illumination system at the light emitting side of a laser light source for shaping and homogenizing. The illumination system typically includes a light pipe or compound eye to homogenize the light and then a relay system to shape the spot. The complex structure of the illumination system results in a large volume of the whole optical engine, which cannot meet the miniaturization requirement of the optical system, and the complex optical system also results in low light efficiency of the optical engine.
Disclosure of Invention
An embodiment of the present invention provides a projection apparatus, including:
The three-color laser emission device comprises a laser light source, a light source module and a light source module, wherein the laser light source is used for emitting three-color laser and comprises three light emitting areas and three diffraction optical elements which are in one-to-one correspondence with the three light emitting areas, and the wavelengths of the laser emitted by the three light emitting areas are different;
The multiplying power lens is positioned on the light emergent side of the diffraction optical element and is used for changing the size of a laser spot;
The light homogenizing element is positioned on the light emitting side of the multiplying power lens and is used for homogenizing laser beams;
the display element is positioned at one side of the dodging element, which is away from the multiplying power lens, and is used for modulating an incident laser beam to form a display image;
the total reflection prism is used for reflecting the emergent light of the multiplying power lens to the display element and transmitting the emergent light of the display element;
the light spots formed when the laser beams emitted from the light emitting area are diffracted by the diffraction optical element and then enter the display element are rectangular light spots, and the long sides of the rectangular light spots are parallel to the slow axis direction of the laser beams emitted from the light emitting area.
In some embodiments of the present invention, three light spots formed by the laser beams output by the three diffractive optical elements when the laser beams are incident to the display element are rectangular light spots;
The centers of the three rectangular light spots coincide and there is an overlap area that covers the active area of the display element.
In some embodiments of the present invention, the area of the rectangular light spot formed by the laser beam output by the diffractive optical element when the laser beam is incident on the display element exceeds 10% -20% of the area of the effective area of the display element.
In some embodiments of the present invention, the magnification lens is a convex lens or a concave lens;
the distance between the display element and the focal plane of the magnification lens is less than or equal to + -5 mm.
In some embodiments of the present invention, the light homogenizing element is a diffuser, and the diffuser is disposed near the total reflection prism;
The diffusion sheet is in a static state, or the diffusion sheet moves along the long side direction of the rectangular light spot.
In some embodiments of the invention, the laser light source further comprises:
and the light combining component is positioned at one side of the three diffraction optical elements, which is away from the three light emitting areas, and is used for combining laser beams with three wavelengths.
In some embodiments of the present invention, the diffractive optical element includes a first region and a second region, and the laser light emitted from the light emitting region passes through the first region and the second region of the diffractive optical element, and then is out of phase by an odd multiple of pi.
In some embodiments of the present invention, the diffractive optical element includes one of the first regions and two of the second regions, the two second regions being respectively located on both sides of the first region in a slow axis direction of the laser beam.
In some embodiments of the present invention, the diffractive optical element is connected to a driving device, and the driving device drives the diffractive optical element to vibrate along the long side direction of the rectangular light spot.
In some embodiments of the present invention, the polarization direction of the laser light emitted from the light emitting area is disordered after passing through the corresponding diffractive optical element.
The projection device provided by the embodiment of the invention comprises a laser light source, and a diffraction optical element, a multiplying power lens, a light homogenizing element, a total reflection prism and a display element which are sequentially arranged along the light emitting path of the laser light source. The laser light source comprises three types of light emergent areas and three diffraction optical elements which are arranged corresponding to the three types of light emergent areas, the wavelengths of laser beams emitted by the three types of light emergent areas are different, light spots formed when laser beams emitted by each light emergent area are incident to the display element after being diffracted by the diffraction optical elements are rectangular light spots, the rectangular light spots are matched with the effective areas of the display element, and the long side directions of the rectangular light spots are parallel to the slow axis directions of the laser beams emitted by the light emergent areas. Therefore, the optical expansion amounts of the laser, the diffraction optical element and the display element can be more matched, so that not only can the diffraction efficiency of the diffraction optical element be improved, but also the light efficiency of the optical system can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an overall architecture of a projection device according to an embodiment of the present invention;
Fig. 2 is a schematic structural diagram of a projection device according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an arrangement of laser chips according to an embodiment of the present invention;
FIG. 4 is a second schematic layout diagram of a laser chip according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of laser spots emitted from a laser chip according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of laser spots emitted by a laser according to an embodiment of the present invention;
fig. 7 is a schematic diagram of laser spots emitted from a light emitting area according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of a correspondence between a light-emitting region and a diffractive optical element according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of spot variation according to an embodiment of the present invention;
Fig. 10 is a schematic diagram of a position correspondence relationship between a display element and a rectangular light spot according to an embodiment of the present invention;
FIG. 11 is a second schematic diagram of a position correspondence relationship between a display device and a rectangular light spot according to an embodiment of the present invention;
FIG. 12 is a third schematic diagram of a position correspondence relationship between a display device and a rectangular light spot according to an embodiment of the present invention;
FIG. 13 is a second schematic view of spot variation according to an embodiment of the present invention;
FIG. 14 is a second schematic diagram of a correspondence between a light-emitting region and a diffractive optical element according to an embodiment of the present invention;
FIG. 15 is a third schematic diagram of the correspondence between the light-emitting region and the diffractive optical element according to the embodiment of the present invention;
Fig. 16 is a schematic structural diagram of a projection system according to an embodiment of the present invention.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a further description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. However, the exemplary embodiments can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus a repetitive description thereof will be omitted. The words expressing the positions and directions described in the present invention are described by taking the drawings as an example, but can be changed according to the needs, and all the changes are included in the protection scope of the present invention. The drawings of the present invention are merely schematic representations of relative positional relationships and are not intended to represent true proportions.
Projection display is a method or apparatus for controlling a light source by planar image information, magnifying and displaying an image on a projection screen using an optical system and a projection space. With the development of projection display technology, projection display is gradually applied to the fields of business activities, conference exhibitions, scientific education, military command, traffic management, centralized monitoring, advertisement entertainment and the like, and the advantages of larger display picture size, clear display and the like are also suitable for the requirement of large-screen display.
The projection device may be based on a Digital Light Processing (DLP) architecture, and a digital micromirror device (Digital Micromirror Device, DMD) is used as a core device, so that the outgoing light of the projection light source is incident on the DMD to generate an image, and then the image light generated by the DMD is incident on the projection lens, imaged by the projection lens, and finally received by the projection screen.
Fig. 1 is a schematic diagram of an overall architecture of a projection device according to an embodiment of the present invention.
As shown in fig. 1, the projection device may include a projection light source 10, an illumination system 20, and a projection lens 30. The projection light source 10, the illumination system 20, and the projection lens 30 may also be collectively referred to as an optical engine.
The projection light source 10 is used for providing illumination light, and the characteristics of the color gamut, the overall brightness, and the like of the projection image are affected by the projection light source 10. In particular embodiments, the projection light source 10 may be a mercury lamp, a light emitting Diode (LIGHT EMITTING Diode, LED) or a laser light source.
The illumination system 20 is located at the light emitting side of the projection light source 10, and is used for shaping and homogenizing the light beam emitted by the projection light source 10. In addition, as shown in fig. 1, the illumination system 20 includes a display element 201, and the display element 201 may employ the DMD described above, and may modulate an incident light beam to form a display image.
The projection lens 30 is located on the light emitting side of the illumination system 20, specifically on the light emitting side of the display element 201, and is used for performing projection imaging on the image formed by the display element 201, and forming an image with a size suitable for viewing by human eyes on a projection surface.
When the display element 201 employs a DMD, since there are special requirements for the size and angle of incidence of the incident light beam, it is necessary to shape and homogenize the light beam emitted from the projection light source 10 before the light beam is incident on the display element 201. As shown in fig. 1, in order to perform operations such as shaping and homogenizing a light beam, a beam adjustment mirror group 103, a light homogenizing element 202, a focusing mirror group 203, and the like are required.
The beam adjusting lens group 103 may be a telescopic lens group, and may be used for performing beam shrinking treatment on an incident beam, the light homogenizing element 202 may be a light pipe or a fly eye lens group, and in fig. 1, the light homogenizing element 202 is used for homogenizing the incident beam, which is illustrated by taking the fly eye lens group as an example of the light homogenizing element 202. In order to meet the light spot size and the incident angle of the display element 201, a focusing lens group 203 is further required to perform focusing treatment on the light beam, and the focused projection light beam can be incident on the display element 201 for modulation.
As shown in fig. 1, in the projection apparatus, in order to make the light spot incident on the DMD meet the requirement, a plurality of groups of lenses and light homogenizing elements are required to be arranged in the light path, so that the whole optical engine has a large volume, and the requirement of miniaturization of the optical system cannot be met.
In view of this, in the embodiment of the present invention, by providing the diffractive optical element in the projection apparatus, by utilizing the characteristics of the diffractive optical element that are small and efficient, the plurality of groups of lenses and the light homogenizing element provided in the optical path can be omitted, thereby reducing the volume of the projection apparatus.
Specifically, as shown in FIG. 2, the projection apparatus includes a laser light source, a magnification lens 203', a dodging element 205, a total reflection prism 204, a display element 201, and a projection lens 30.
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 laser power, the requirements of industrial application are met, and the laser is gradually used as a light source for illumination. The projection device uses a laser as a projection light source, gradually replaces mercury lamp illumination, and compared with an LED light source, the laser has the advantages of small optical expansion and high brightness, so that the projection device is widely applied.
In the embodiment of the invention, the diffractive optical element 104 is applied in the laser light source, and the diffractive optical element 104 is sensitive to the wavelength and the incident angle of the incident light, so that the laser has a narrower half-peak width and high collimation degree, and is more suitable for the laser light source.
As shown in fig. 2, the laser light source can emit three-color laser light, and specifically can be divided into three types of light emitting areas 101, namely a first light emitting area 101-1, a second light emitting area 101-2 and a third light emitting area 101-3. The three types of light emitting areas are used for emitting laser with different wavelengths. The three types of light emitting regions 101 may be different regions in one laser capable of emitting three-color laser light, or may be three lasers capable of emitting laser light of different colors, which is not limited herein.
The laser light source further includes three diffractive optical elements 104 disposed on the light-emitting sides of the three types of light-emitting regions 101, and disposed in one-to-one correspondence with the three types of light-emitting regions 101. A diffractive optical element (DIFFRACTIVE OPTICAL ELEMENTS, DOE for short) is an optical element that can change the propagation characteristics of light. The diffractive optical element 104 has a relatively thin thickness and has microstructures on at least one side surface thereof, the microstructures typically having a size on the order of microns, which can alter the phase of incident light, thereby altering the propagation path of the light on a microscopic scale, and effecting shaping and homogenization of the light beam.
The shaping principle of the beam by the diffractive optical element 104 is mainly based on diffraction and interference phenomena of light. When a light beam passes through the diffractive optical element 104, the microstructure of the diffractive optical element 104 changes the propagation direction of the light, and when different light waves meet in space, an interference phenomenon of mutual superposition occurs. By precisely designing the microstructure of the diffractive optical element 104, the effects of diffraction and interference can be controlled, thereby achieving shaping of the light beam.
Since the diffractive optical element 104 is disposed on the light-emitting side of the light-emitting region of the laser light source, the incident laser beam can be shaped and homogenized, and therefore, there is no need to dispose more optical elements in the projection apparatus for shaping and homogenizing the laser beam. As shown in fig. 2, the laser beams emitted from the three light emitting areas 101 of the laser light source are diffracted by the diffractive optical element 104 and then combined, and the combined laser beams are focused on the display element 201 only by the magnification lens 203', and the projection lens performs projection imaging on the display image modulated by the display element 201, so as to obtain a projection image with a larger size.
As shown in fig. 2, by providing the diffractive optical element 104 in the laser light source, the laser light with different wavelengths is diffracted and shaped before the light combination, and the illumination requirement of the display element can be satisfied only by adjusting the size of the combined light beam after the light combination. Optical devices such as a plurality of groups of lenses, light homogenizing elements and the like can be omitted in the optical path of the optical engine, so that the whole volume of the optical engine is reduced, the optical path is simpler, and the miniaturized design of projection equipment can be met.
The embodiment of the invention is exemplified by taking a laser light source as an example, wherein the laser light source can emit three-color laser light. As shown in fig. 3 and 4, the laser light source may include a plurality of laser chips arranged in an array, and is divided into a plurality of first laser chips a1, a plurality of second laser chips a2, and a plurality of third laser chips a3, where the first laser chips a1 are located in the first light emitting region 101-1, the second laser chips a2 are located in the second light emitting region 101-2, and the third laser chips a3 are located in the third light emitting region 101-3.
In some embodiments, as shown in fig. 3, the laser light source may employ MCL lasers, and the first, second and third laser chips a1, a2 and a3 are arranged in a matrix of 4×7 in the first and second directions x, y. The number of the first laser chips a1 and the second laser chips a2 is smaller than that of the third laser chips a3, the first laser chips a1 are arranged in a row along the first direction x, the second laser chips a2 are arranged in a row along the first direction, and the third laser chips a3 are arranged in two rows along the first direction.
In some embodiments, as shown in fig. 4, the laser light source may employ NUBB lasers or NUMB lasers, and the first laser chip a1, the second laser chip a2, and the third laser chip a3 are arranged in an array along the first direction x and the second direction y. The number of the first laser chips a1 and the second laser chips a2 is smaller than the number of the third laser chips a3, the first laser chips a1 and the second laser chips a2 are arranged in a line along the first direction x, and the third laser chips a3 are arranged in a line along the first direction.
The above-mentioned lasers are all semiconductor lasers, because of the problems of materials and efficiency, etc., a larger number of red laser chips are required to be arranged in general, so that the above-mentioned third laser chip a3 may be a red laser chip, the second laser chip a2 may be a green laser chip, and the first laser chip a1 may be a blue laser chip.
It should be noted that the arrangement of the laser chips shown in fig. 3 and fig. 4 is only used as an example, and in practical applications, the types of the laser chips included in the laser device, the wavelength of the laser emitted by each laser chip, and the number and arrangement of each laser chip are not limited.
As shown in fig. 5, the laser chip a may be formed of a plurality of stacked semiconductor layers, and the emitted laser beams have different divergence angles in different directions, so that the laser beams form an elliptical-like laser spot B in the far field, the major axis direction of the ellipse corresponds to a plane parallel to the stacked structure of the laser chip (i.e., a plane formed by the first direction x and the second direction y), the minor axis direction of the ellipse corresponds to the stacked direction of the laser chip (i.e., the third direction z in fig. 5), and the divergence angle of the laser light emitted by the laser chip a in the direction parallel to the plane of the stacked structure is larger than the divergence angle in the stacked direction. Therefore, the major axis direction of the ellipse can be referred to as the fast axis direction k1 of the laser light, and the minor axis direction of the ellipse can be referred to as the slow axis direction k2 of the laser light.
As shown in fig. 6, the laser does not directly emit laser light from the laser chip a, but a reflecting prism f is provided on the light-emitting side of the laser chip a, and the laser light emitted from the laser chip a is incident on the reflecting prism f and is reflected by the reflecting prism f toward the light-emitting port of the laser. In addition, the laser device is further provided with a plurality of collimating lenses t corresponding to the laser chips a one by one at the light outlet, and the collimating lenses t are used for collimating the laser beams reflected by the reflecting prisms f, and as the laser beams have larger divergence angles in the fast axis direction k1, the collimating lenses t are usually designed aiming at the divergence angles of the laser beams in the fast axis direction k1, so that the divergence angles of the laser beams in the fast axis direction k1 after passing through the collimating lenses t are smaller than the divergence angles in the slow axis direction k 2.
As shown in fig. 3 and 4, the same type of laser chips are generally arranged along the first direction x, so that the slow axis direction of the laser light emitted from the laser light outlet is parallel to the first direction x, and the fast axis direction is parallel to the second direction y.
Taking the laser shown in fig. 3 as an example, the laser spots of the three types of light emitting areas can be formed at the positions of the light emitting openings as shown in fig. 7. The laser beam emitted from the first laser chip a1 forms a first laser spot B1 at the light outlet, the laser beam emitted from the second laser chip a2 forms a second laser spot B2 at the light outlet, and the laser beam emitted from the third laser chip a3 forms a third laser spot B3 at the light outlet. Then, as a whole, the laser emitted from the first light emitting region 101-1 forms a first laser spot array BL1 at the light emitting port, the laser emitted from the second light emitting region 101-2 forms a second laser spot array BL2 at the light emitting port, and the laser emitted from the third light emitting region 101-3 forms a third laser spot array BL3 at the light emitting port. Each laser spot array can be regarded as a larger-sized spot as a whole, and because each laser spot has a larger divergence angle along the slow axis direction (i.e., the first direction x) and a smaller divergence angle along the fast axis direction (i.e., the second direction y), the divergence angle of the laser spot array (the whole spot) formed at the light outlet of the laser device along the first direction x is larger than the divergence angle along the second direction y, and the size of the spot formed by the whole laser spot array along the first direction x is also larger than the size of the spot formed by the whole laser spot array along the second direction y.
The etendue is related to the beam area and the beam solid angle, the larger the beam solid angle means the larger the divergence angle of the beam, and the larger the beam area means the larger the spot size. For the laser adopted in the embodiment of the invention, the light spot formed by the laser emitted by each light emitting area along the first direction x has a larger divergence angle and a larger light spot size compared with the light spot formed by the laser emitted by each light emitting area along the second direction y, so that the optical expansion of the light beam emitted by the laser along the first direction x is larger than that along the second direction y.
As shown in fig. 8, three diffractive optical elements provided corresponding to the three types of light-emitting regions 101 are a first diffractive optical element 104-1, a second diffractive optical element 104-2, and a third diffractive optical element 104-3, respectively. The first diffractive optical element 104-1 is disposed corresponding to the first light-emitting region 101-1, the second diffractive optical element 104-2 is disposed corresponding to the second light-emitting region 101-2, and the third diffractive optical element 104-3 is disposed corresponding to the second light-emitting region 101-3. The laser beam emitted from each light emitting area still has a certain divergence angle, and the larger the divergence degree of the laser beam is, the larger the formed light spot size is along with the increase of the optical path. Therefore, in the embodiment of the present invention, the diffractive optical element may be disposed near the corresponding light-emitting region, so that the size of the diffractive optical element is controlled not to be excessively large.
As shown in fig. 9, for each light emitting region 101, the diffractive optical element 104 may shape the laser beam emitted from its corresponding light emitting region and image the emission spot at the position of the display element 201. The spot formed by imaging the spot emitted from the diffractive optical element 104 at the display element position is hereinafter referred to as an imaging spot of the diffractive optical element. The imaging light spot of the diffractive optical element 104 has the same shape as the effective area of the display element 201, and when the display element 201 adopts the DMD, the imaging light spot of the diffractive optical element 104 is a rectangular light spot CB having an aspect ratio of 16:9. The imaging spot of the diffractive optical element 104 is a rectangular spot, meaning that the etendue of the light beam emitted from the diffractive optical element 104 in the long side direction of the rectangular spot CB is larger than the etendue in the short side direction of the rectangular spot CB. In order to more match the etendue of the three elements, the microstructure of the diffractive optical element may be designed such that the long side of the rectangular spot CB imaged at the position of the display element 201 is parallel to the slow axis direction of the laser beam emitted from the light emitting region 101 and the short side of the rectangular spot CB is parallel to the fast axis direction of the laser beam emitted from the light emitting region 101. This can not only improve the diffraction efficiency of the diffractive optical element, but also improve the light efficiency of the optical system.
As shown in fig. 2, the laser beams emitted from the three types of light emitting regions 101 of the laser light source pass through the corresponding diffractive optical elements 104, and then enter the light combining module 102 to combine.
Still taking the laser shown in fig. 3 as an example, when the laser shown in fig. 3 is used for light combination, the light combination assembly 102 may include a first light combination member 102-1, a second light combination member 102-2, and a third light combination member 102-3. The first light combining element 102-1 is disposed corresponding to the first light emitting area 101-1, the second light combining element 102-2 is disposed corresponding to the second light emitting area 101-2, and the third light combining element 102-3 is disposed corresponding to the third light emitting area 101-3. The first light combining element 102-1 is configured to reflect the laser light emitted from the first light emitting region 101-1 toward the second light combining element 102-2, the second light combining element 102-2 is configured to combine the laser light emitted from the first light emitting region 101-1 with the laser light emitted from the second light emitting region 101-2 to emit the combined light toward the third light combining element 102-3, and finally, the combined light is configured to combine the laser light emitted from the first light emitting region 101-1, the laser light emitted from the second light emitting region 101-2, and the laser light emitted from the third light emitting region 101-3 by the third light combining element 102-3.
Before the laser beams emitted from each light emitting area 101 of the laser source are incident on the light combining component 102, the laser beams are shaped by the corresponding diffraction optical element 104, so that the laser spots incident on the light combining component 102 are rectangular spots, the long sides of the three rectangular spots are parallel to each other, and the short sides of the three rectangular spots are parallel to each other. The light combining component 102 combines the three-color laser light along the second direction y, the three-color rectangular light spots after the light combination are overlapped together, and the centers of the three-color rectangular light spots are overlapped.
As shown in fig. 2, the three-color laser beams after the light combination pass through a magnification lens 203' and are focused at the position of the display element 201. A light equalizing element 205 and a total reflection prism 204 are also provided between the magnification lens 203' and the display element 201.
The magnification lens 203' is used to adjust the size of the integrated light spot to be more suitable for the size of the active area of the display element 201. The magnification lens 203' may be a convex lens or a concave lens according to the specifications of the display element 201, and is not limited thereto.
In some embodiments, the light homogenizing element 205 may employ a diffuser, located between the magnification lens 203' and the total reflection prism 204, for homogenizing the incident laser beam. The diffuser is positioned near the total reflection prism 204, and may be in a stationary state or in a moving state. The diffusion sheet can be a flat plate with diffusion particles dispersed therein, has a scattering effect on incident light, and can lead the polarization direction of emergent laser to be in a disordered state by matching with high-frequency motion of the diffusion sheet, thereby solving the problem of laser speckle. The diffusion sheet may move along the long side direction of the rectangular light spot or may perform a tilting movement along the diagonal direction, which is not limited herein.
The total reflection prism 204 can separate the illumination beam and the imaging beam, and the total reflection prism 204 reflects the outgoing light of the magnification lens 203' to the display element 201, and transmits the outgoing light modulated by the display element 201 to the projection lens 30 for projection imaging.
The diffractive optical element 104 and the magnification lens 203' each have an imaging function, and when the diffractive optical element 104 is designed, the laser beam emitted from each light emitting region 101 of the laser light source is ideally diffracted by the diffractive optical element 104, and then sufficiently homogenized, and a clear rectangular light spot which completely coincides with the effective region of the display element 201 is formed at the position of the display element 201.
However, in practical application, the diffraction efficiency of the diffractive optical element 104 cannot reach 100%, a certain divergence angle still exists in the laser beam passing through the diffractive optical element, and then, in consideration of the tolerance in the optical path and other problems, when three diffractive optical elements 104 are designed, the embodiment of the invention can make the imaging light spots at the position of the display element 201 be rectangular light spots after the emergent light beams of the three types of light emergent regions 101 pass through the three diffractive optical elements 104, and the size of the three rectangular light spots can be slightly larger than the effective region of the display element 201.
In some embodiments, as shown in fig. 10, the area of the imaging spot (rectangular spot CB) of the diffractive optical element may be 10% -20% larger than the area of the active region 201a of the display element. Meanwhile, the centers of the imaging spots of the three diffractive optical elements coincide with each other, and have overlapping areas, which can cover the effective area of the display element 201, to ensure uniform energy distribution and color distribution of the three-color laser beams incident on the display element 201.
In the case of the semiconductor red laser chip, the laser beam emitted therefrom has two light emitting points, and when the laser beam is incident on the display element after being diffracted by the corresponding diffractive optical element 104, two light spots CB1 and CB2 as shown in fig. 11 are formed, and the two light spots are different in size, which makes the light intensity distribution in the effective area 201a of the display element uneven, and affects the display effect.
To overcome this problem, as shown in fig. 12, the diffractive optical element 104 corresponding to the red laser chip may be specially designed, and the distribution of the microstructure thereof may be changed, so as to change the phase distribution of the incident laser, increase the diffraction angle of the diffracted beam parallel to the long side direction of the rectangular light spot, increase the length of the red laser beam output by the diffractive optical element on the long side of the rectangular light spot formed by the display element, thereby increasing the lengths of the long sides of the light spots CB1 and CB2 formed by the dual light emitting points, and increase the length of the overlapping region of the two light spots, so that the overlapping region may cover the effective region 201a of the display element, and overcome the problem of uneven energy distribution of the red laser light spot incident on the effective region 201a of the display element.
The three-color laser beams after light combination still have a certain divergence angle, and the sharpest imaging cannot be obtained when the three-color laser beams are incident on the display element 201 along with the increase of the optical path, so that the magnification lens 203' is arranged between the light combination assembly 102 and the display element 201, the display element 201 can be positioned in the range of 5mm in front of and behind the focal plane of the magnification lens 203', and after passing through the magnification lens 203', the three-color laser beams are imaged as rectangular light spots with clear boundaries and uniform energy distribution when the three-color laser beams are incident on the display element 201. And the diffuser may be positioned within the focal length of the magnification lens 203' for further homogenizing the combined light beam before it is incident on the display element 201.
The following describes the optical engine shown in fig. 2 with reference to fig. 13, specifically, the divergence degree of the light spot, the size of the light spot, and the shape of the light spot after the laser beam emitted from the laser passes through the combining element in the optical path, and fig. 10 illustrates the optical path of a light emitting area 101 of the laser light source, and similar optical paths of other light emitting areas, which can be seen from each other.
When the laser shown in fig. 3 is used, as shown in fig. 13, the laser light emitted from the light emitting region 101 forms 1×7 elliptical spots at the position (1) before the laser light enters the diffractive optical element 104, where each elliptical spot is a spot formed by the laser beam emitted from one laser chip at the position of the light emitting opening of the laser. The outgoing light of the light outgoing area 101 can be regarded as a laser beam with a certain width, and then the outgoing light of each laser chip in the light outgoing area 101 can be regarded as a sub-beam, the sub-beams outgoing from the light outgoing area 101 are separated from each other, the divergence angle in the slow axis direction k2 is larger than the divergence angle in the fast axis direction k1, and the energy distribution of the sub-beams is gaussian.
When 1×7 sub-beams emitted from the light emitting region 101 are incident on the diffractive optical element 104 and are diffracted by the diffractive optical element 104, the energy distribution of each sub-beam is homogenized, the main optical axes of the sub-beams emitted from the diffractive optical element 104 are parallel to each other, 1×7 rectangular light spots separated from each other are formed at the emission position (2) of the diffractive optical element 104, the divergence angles of the sub-beams emitted from the diffractive optical element 104 in the fast axis direction k1 and the slow axis direction k2 are reduced, but the rectangular light spots formed at the position (2) are larger than those of the elliptical light spots formed at the position (1) through propagation of a certain optical path.
After the sub-beams emitted from the diffractive optical element 104 pass through the light combination of the light combination unit 102, before entering the magnification lens 203', 1×7 mutually separated rectangular light spots are formed at a position (3) between the light combination unit 102 and the magnification lens 203', and after the sub-beams pass through the light combination, the main optical axes of the sub-beams are still mutually parallel, the divergence angle is unchanged, but the size of the rectangular light spots is increased after a certain optical path.
When the sub-beams after light combination enter the multiplying power lens 203', the multiplying power lens 203' focuses the sub-beams, the main optical axes of the sub-beams are not parallel any more, the sub-beams converge or diverge in the process of propagating to the display element 201 through the multiplying power lens 203', gradually approach each other, and finally, the sub-beams are combined into a rectangular light spot with clear outline at the position (4) corresponding to the light incident surface of the display element 201, and the rectangular light spot has uniform energy distribution and meets the flat top distribution.
Finally, the display element 201 modulates the incident light beam to form a display image, and emits the modulated light beam to the projection lens 30. At the far field location (5), the previously combined sub-beams gradually diverge as the propagation distance increases, so that the profile of the spot gradually becomes blurred and the sharpness is degraded. At this time, a clear projection image is obtained on the projection surface by matching with a reasonable optical design of the projection lens.
The beam and spot changing process is only directed to one type of light emitting area 101, and the beam and spot changing processes of the other two types of light emitting areas are similar to the above. It should be noted that, since the divergence angles and the spot sizes of the red, green and blue lasers are not the same, three-color rectangular spots with clear outlines and uniform energy distribution can be obtained on the light incident surface of the display element 201, but the sizes of the three-color rectangular spots are not the same, and in general, the size of the red spot is larger than the size of the green spot, and the size of the green spot is larger than the size of the blue spot. However, as long as the centers of the three-color rectangular light spots are overlapped, and the effective area of the display element can be covered, the image display without color bias can be obtained.
In the embodiment of the invention, when the three light emitting areas of the laser light source can be different areas of the same laser, the diffractive optical element can also adopt one element, and the diffractive optical element is designed separately corresponding to the different light emitting areas. When the three light emitting areas of the laser light source are respectively three lasers emitting different wavelengths, three diffraction optical elements can be applied.
The microstructure of the surface of the diffractive optical element 104 is fabricated by a semiconductor processing process. The topography, size, and refractive index of the surface of the diffractive optical element 104 affect the phase of the light. In order to obtain an image with a uniform energy distribution and a clear profile at the location of the display element 201, the phase of the diffractive optical element needs to be finely designed according to the input parameters of the incident light beam and the output parameters of the outgoing light beam.
The input parameters of the incident light beam can comprise wavelength, light beam quality, beam waist radius, light intensity distribution and the like when the laser light beam emitted by each laser chip is incident to the corresponding area of the corresponding diffraction optical element, and the input parameters of the emergent light beam can comprise the size, the emergent distance, the diffraction order, the light intensity distribution and the like of a light spot when the laser light beam is incident to the position of the display element.
The diffraction optical element may be designed by using a GS algorithm, a Y-G algorithm, or the like, and the phase of the diffraction optical element may be calculated, and the phase of the diffraction optical element may be compressed to [0,2 pi ] from the periodicity of the phase. However, the current processing capability is limited in that microstructures with continuous phases cannot be processed, and thus continuous phases can be subdivided into stepped microstructures with different heights.
The following describes the design concept of the GS algorithm for designing the phase distribution of the diffractive optical element. When the amplitude distribution of the input field (incident laser beam) and the target field (laser beam at the display element position) is known, when the initial phase can be selected to be random, fourier change is performed on the initial phase and the input field amplitude to obtain a complex amplitude of a frequency domain, the phase in the complex amplitude of the frequency domain is extracted, the amplitude of the target field is added, inverse Fourier change is performed on the obtained complex amplitude to obtain a complex amplitude of a space domain, the phase in the complex amplitude is extracted, the amplitude of the input field is added to obtain a new complex amplitude, and Fourier change is performed on the new complex amplitude to obtain the complex amplitude of the frequency domain. The fourier transform is iterated continuously, and the phase of the finally extracted spatial complex amplitude is the phase of the diffraction optical element.
In addition, other algorithms can be adopted to design the phase of the diffraction optical element, the embodiment of the invention only uses the GS algorithm as an example, and in practical application, the diffraction optical element can be designed in a reasonable mode according to the requirement.
The projection device adopts the laser light source, and the laser has stronger coherence, so that the problem of laser speckle is easy to occur, but the embodiment of the invention is provided with the diffraction optical element in the laser light source, the diffraction optical element can modulate the phase of light, and the diffraction optical element can be designed to have an additional phase adjustment function besides the modulation function on the incident light beam, so that the problem of laser speckle is improved.
In some embodiments, as shown in fig. 14, the diffractive optical element includes a first region 104a and a second region 104b, and the laser light exiting from the light exit region 101 passes through the first region 104a and the second region 104b of the corresponding diffractive optical element and then is out of phase by an odd multiple of pi.
The laser light emitted from the laser light source is usually polarized light, for example, the laser light emitted from the red laser chip is p polarized light, and the laser light emitted from the green laser chip and the blue laser chip is s polarized light. The polarization direction and the phase of the laser emitted by the same laser chip are the same, so that the laser has stronger coherence and is easy to emit laser speckles in the projection display process. In order to solve this problem, the diffractive optical element may be divided into two regions when the diffractive optical element is designed, and the phase distribution of the diffractive optical element is required to be an odd multiple of pi while satisfying the shaping of the incident laser beam into a rectangular spot of a set size and the energy distribution is uniform, so that the polarization direction of the laser light emitted from the first region and the polarization direction of the laser light emitted from the second region may be perpendicular to each other, and if the areas of the first region and the second region are the same, the polarization direction of the light emitted from one half of the diffractive optical element and the polarization direction of the light emitted from the other half of the diffractive optical element may be perpendicular, so that the coherence of the laser light may be reduced to the maximum, thereby improving the formation of laser speckle.
In some embodiments, as shown in fig. 15, the diffractive optical element includes one first region 104a and two second regions 104b, the two second regions 104b being located on both sides of the first region 104a in the first direction x (the long side direction of the rectangular light spot), respectively. The second region 104b is divided into two parts, and the symmetrical design on both sides of the first region 104a can make the phase adjustment of the outgoing laser be symmetrically distributed, so as to better improve the problem of laser speckle.
In some embodiments, a driving device may be further disposed in the projection apparatus, where the driving device is connected to the diffractive optical element, and the driving device may drive the diffractive optical element 104 to vibrate along the first direction x (the long side direction of the rectangular light spot). For example, the diffractive optical element may reciprocate at a relatively high frequency along the first direction x, so that each time the outgoing light passing through the diffractive optical element may form an imaging light spot, the effects of the imaging light spots after multiple vibrations are superimposed to be regarded as homogenizing the light spot. The spatial phase distribution of the outgoing light can thus also be made more uniform, so that the problem of laser speckle is ameliorated.
In some embodiments, the diffractive optical element may be further designed such that the polarization direction of the laser light emitted from the light emitting region 101 is in a disordered state after passing through the corresponding diffractive optical element 104, that is, after the phase distribution of the diffractive optical element satisfies a specific shaping and homogenizing effect, a random phase is added in the diffractive optical element, so that the polarization direction of the emitted light is in a disordered state, and the strong coherence of the laser light is destroyed, thereby achieving the purpose of resolving the speckle.
Based on the same inventive concept, an embodiment of the present invention also provides a projection system, as shown in fig. 16, including a projection apparatus 1 and a projection screen 2.
The projection screen 2 is located on the light exit side of the projection device 1, with the viewer facing the projection screen 2. The projection device 1 emits projection light, which is incident on the projection screen 2 and emitted in the direction of the viewer through the projection screen 2, so that the viewer views the projection image.
When the projection apparatus 1 and the viewer are located on the same side of the projection screen 2, this projection system is referred to as a front projection system, and when the projection apparatus 1 and the viewer are located on both sides of the projection screen 2, respectively, this projection system is referred to as a rear projection system. The front projection system is a system in which projection light is emitted from a projection device 1 to a projection screen 2, and the projection light is reflected by the projection screen 2 to a viewer, so that the viewer views a projection image. The rear projection system is that the projection device 1 emits projection light to the projection screen 2, and the projection light is emitted to the audience through the projection screen 2, so that the audience can watch the projection image.
The projection device 1 may employ any of the above projection devices including a laser light source, an illumination system, and a projection lens. The laser light source comprises three types of light emergent areas and three diffraction optical elements, and the wavelengths of laser light emitted by the three types of light emergent areas are different. The illumination system comprises a multiplying power lens, a dodging element, a total reflection prism and a display element, wherein the display element can modulate incident laser to form a display image and then the display image is incident to the projection lens to carry out projection imaging.
The wavelength of the laser emitted by each light emitting area of the laser source is different, and a light spot formed when the laser beam emitted by each light emitting area is diffracted by the diffraction optical element and then enters the display element is a rectangular light spot, the rectangular light spot is matched with the effective area of the display element, and the long side direction of the rectangular light spot is parallel to the slow axis direction of the laser beam emitted by the light emitting area. Therefore, the optical expansion amounts of the laser, the diffraction optical element and the display element can be more matched, so that not only can the diffraction efficiency of the diffraction optical element be improved, but also the light efficiency of the optical system can be improved.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (10)
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410939717.6A CN121325493A (en) | 2024-07-12 | 2024-07-12 | A projection device |
| PCT/CN2025/080995 WO2025241656A1 (en) | 2024-05-22 | 2025-03-06 | Projection device and diffractive optical element |
| PCT/CN2025/107369 WO2026012327A1 (en) | 2024-07-12 | 2025-07-07 | Projection apparatus and projection system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410939717.6A CN121325493A (en) | 2024-07-12 | 2024-07-12 | A projection device |
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| Publication Number | Publication Date |
|---|---|
| CN121325493A true CN121325493A (en) | 2026-01-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202410939717.6A Pending CN121325493A (en) | 2024-05-22 | 2024-07-12 | A projection device |
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| CN (1) | CN121325493A (en) |
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