Projection equipment and projection system

Abstract

The utility model discloses projection equipment and a projection system. The projection equipment comprises a laser light source, and a diffractive optical element, a focusing lens and a display element which are sequentially arranged along a light emitting path of the laser light source. Wavelength of laser emitted by each light-emitting area of the laser light source is different, and diffracted light shift phase is increased when the diffractive optical element is designed, so that when laser beams emitted by each light-emitting area are diffracted by the diffractive optical element and then emitted, diffracted light shifts a set angle relative to zero-order light. Therefore, a diffraction light spot and a zero-order light spot which are formed on the display element after emergent light of the diffractive optical element passes through the focusing lens can be separated from each other, the diffraction light spot covers an effective area of the display element, the zero-order light spot is not overlapped with the display element, and adverse effects of the zero-order light spot on a projected image are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of projection, in particular to a projection device and a projection system. Background Art

[0002] Laser projection display technology, also known as laser projection technology or laser display technology, is a technology that uses laser as a light source for projection display. Laser projection can most truly reproduce the rich and colorful colors of the objective world, providing more shocking expressiveness. Its color gamut coverage rate can reach more than 90% of the color space that the human eye can recognize, which is more than twice that of traditional displays.

[0003] In order to optimize the structure of the projection system, a diffractive optical element can be set in the projection system, and the diffractive effect of the diffractive optical element is used to improve the projection display effect. However, due to the current process limitations of the diffractive optical element, a part of the light incident on the diffractive optical element is directly emitted without diffraction, forming a bright spot on the imaging surface, affecting the energy distribution uniformity of the imaging picture and reducing the image quality. Summary of the Utility Model

[0004] In the first aspect of the embodiments of the present utility model, a projection device is provided, including:

[0005] A laser light source for emitting three-color laser; the laser light source includes: three types of light-emitting regions and three diffractive optical elements corresponding to the three types of light-emitting regions one by one, and the wavelengths of the laser emitted by the three types of light-emitting regions are different;

[0006] A focusing lens located on the light-emitting side of the diffractive optical element;

[0007] A display element located on the side of the focusing lens away from the laser light source, for modulating the incident laser beam to form a display image;

[0008] Wherein, the laser beam emitted from the light-emitting region forms a diffractive spot and a zero-order spot when passing through the diffractive optical element and the focusing lens and then entering the display element, the diffractive spot covers the effective area of the display element, and the zero-order spot is separated from the diffractive spot.

[0009] In some embodiments of the present utility model, it further includes:

[0010] A light combining component located on the side of the three diffractive optical elements away from the three types of light-emitting regions, for combining the three-color laser beams and reflecting them to the focusing lens;

[0011] The three diffracted light spots formed when the laser beams emitted from the three types of light-emitting regions are incident on the display element after passing through the corresponding diffractive optical elements, the light combining component, and the focusing lens are all rectangular light spots; the centers of the three rectangular light spots coincide and there is an overlapping region, and the overlapping region covers the effective region of the display element.

[0012] In some embodiments of the present invention, the light combining component includes: three light combining members arranged in parallel with each other and corresponding to the three types of light-emitting regions one by one; the light combining member is inclined with respect to the light-emitting surface of the corresponding light-emitting region.

[0013] In some embodiments of the present invention, the diffracted light after passing through the diffractive optical element and the focusing lens forms the diffracted light spot, and the zero-order light after passing through the diffractive optical element and the focusing lens forms the zero-order light spot;

[0014] There is a set angle between the beam center of the diffracted light and the beam center of the zero-order light, and the set angle satisfies:

[0015] θ = arctan(df);

[0016] Wherein, θ represents the set angle formed by the beam center of the diffracted light and the beam center of the zero-order light, d represents the distance between the center of the diffracted light spot and the center of the zero-order light spot, and f represents the focal length of the focusing lens.

[0017] In some embodiments of the present invention, the included angle between the light combining member and the light-emitting surface of the corresponding light-emitting region is 45°;

[0018] The beam center of the zero-order light coincides with the first direction, and the included angle between the beam center of the diffracted light and the first direction is θ; the first direction is parallel to the light-emitting surface of the light-emitting region and forms a 45° angle with the light combining member.

[0019] In some embodiments of the present invention, the included angle between the light combining member and the light-emitting surface of the corresponding light-emitting region is

[0020] The beam center of the diffracted light coincides with the first direction, and the included angle between the beam center of the zero-order light and the first direction is θ; the first direction is parallel to the light-emitting surface of the light-emitting region and forms an included angle with the light combining member.

[0021] In some embodiments of the present invention, it further includes:

[0022] A total reflection prism is located between the focusing lens and the display element; the total reflection prism includes a light incident surface and a total reflection surface; the light emitted from the focusing lens is incident into the total reflection prism through the light incident surface, and after total reflection occurs on the total reflection surface, it is emitted towards the display element;

[0023] The incident angle of the diffracted light incident on the light incident surface of the total reflection prism satisfies:

[0024]

[0025] Wherein, α1 represents the incident angle of the diffracted light incident on the light incident surface of the total reflection prism, α2 represents the included angle between the light incident surface and the total reflection surface of the total reflection prism, n represents the refractive index of the total reflection prism, and F represents the F-number of the optical system.

[0026] In some embodiments of the present utility model, light-shielding sheets are arranged around the display element;

[0027] The diffracted light is incident on the display element, and the zero-order light is incident on the light-shielding sheet.

[0028] In some embodiments of the present utility model, it further includes:

[0029] A light homogenizing element is located between the focusing lens and the total reflection prism, and is used for homogenizing the laser beam;

[0030] The light homogenizing element adopts at least one of a diffuser, a fly-eye lens, a diffuser wheel or a moving diffuser.

[0031] In a second aspect of the embodiments of the present utility model, a projection system is provided, including:

[0032] A projection device, and the projection device is any one of the above projection devices;

[0033] A projection screen, which is located on the light-emitting side of the projection device.

[0034] The projection device and the projection system provided by the embodiments of the present utility model include: a laser light source, and a diffractive optical element, a focusing lens and a display element sequentially arranged along the light-emitting path of the laser light source. The wavelengths of the laser lights emitted from each light-emitting area of the laser light source are different. When designing the diffractive optical element, the diffracted light offset phase is increased, so that the diffracted light of the laser beam emitted from each light-emitting area is offset by a set angle relative to the zero-order light when it is emitted after being diffracted by the diffractive optical element. Thus, the diffracted light spot and the zero-order light spot formed on the display element after the light emitted from the diffractive optical element passes through the focusing lens are separated from each other. The diffracted light spot covers the effective area of the display element, and the zero-order light spot does not overlap with the display element, thereby avoiding the adverse effects of the zero-order light spot on the projection image. Description of the Drawings

[0035] To more clearly illustrate the technical solutions of the embodiments of the present utility model, the accompanying drawings required for use in the embodiments of the present utility model will be briefly introduced below. Obviously, the accompanying drawings introduced below are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0036] Figure 1 Schematic diagram of the overall architecture of the projection device provided by the embodiment of the present utility model;

[0037] Figure 2 One of the structural schematic diagrams of the projection device provided by the embodiment of the present utility model;

[0038] Figure 3 One of the layout schematic diagrams of the laser chips provided by the embodiment of the present utility model;

[0039] Figure 4 Another layout schematic diagram of the laser chips provided by the embodiment of the present utility model;

[0040] Figure 5 Schematic diagram of the corresponding relationship between the light-emitting area and the diffractive optical element provided by the embodiment of the present utility model;

[0041] Figure 6 One of the imaging principle schematic diagrams provided by the embodiment of the present utility model;

[0042] Figure 7 Another structural schematic diagram of the projection device provided by the embodiment of the present utility model;

[0043] Figure 8 Another imaging principle schematic diagram provided by the embodiment of the present utility model;

[0044] Figure 9 Another structural schematic diagram of the projection device provided by the embodiment of the present utility model;

[0045] Figure 10 Another imaging principle schematic diagram provided by the embodiment of the present utility model;

[0046] Figure 11 Total reflection optical path principle schematic diagram provided by the embodiment of the present utility model;

[0047] Figure 12 Another structural schematic diagram of the projection device provided by the embodiment of the present utility model;

[0048] Figure 13 Schematic diagram of the structure of the projection system provided by the embodiment of the present utility model. Detailed implementation manners

[0049] In order to make the above-mentioned objects, features and advantages of the present utility model more obvious and understandable, the present utility model will be further described below in conjunction with the drawings and embodiments. However, the exemplary embodiments can be implemented in various forms and should not be construed as being limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present utility model more comprehensive and complete, and to 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 the repeated description thereof will be omitted. The words expressing positions and directions described in the present utility model are all illustrated by taking the drawings as examples, but can be changed according to needs, and all the changes made are included in the protection scope of the present utility model. The drawings of the present utility model are only used to illustrate the relative position relationship and do not represent the actual proportion.

[0050] Projection display is a method or device that controls a light source by plane image information and uses an optical system and a projection space to magnify and display an image on a projection screen. With the development of projection display technology, projection display is gradually applied to fields such as business activities, conference exhibitions, science education, military command, traffic management, centralized monitoring, and advertising and entertainment. Its advantages such as a large display screen size and clear display also meet the requirements of large-screen display.

[0051] The projection device can be based on the Digital Light Processing (DLP) architecture, with a Digital Micromirror Device (DMD) as the core device. The emitted 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, and the projection lens performs imaging, and finally the projection screen receives it.

[0052] Figure 1 It is a schematic diagram of the overall architecture of the projection device provided by the embodiment of the present utility model.

[0053] As Figure 1 shown, 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.

[0054] Among them, the projection light source 10 is used to provide illumination light, and the characteristics such as the color gamut and overall brightness of the projection image are all affected by the projection light source 10. In specific implementation, the projection light source 10 may adopt a mercury lamp, a Light Emitting Diode (LED), or a laser light source.

[0055] The illumination system 20 is located on the light-emitting side of the projection light source 10 and is used to shape and homogenize the light beam emitted by the projection light source 10. Additionally, as Figure 1 shown, the illumination system 20 includes a display element 201. The display element 201 can adopt the above-mentioned DMD and can modulate the incident light beam to form a display image.

[0056] 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 to project and image the image formed by the display element 201 to form an image of a size suitable for human eyes to view on the projection plane.

[0057] When the display element 201 adopts a DMD, there are special requirements for the size and incident angle of the incident light beam. Therefore, operations such as shaping and homogenizing the light beam emitted by the projection light source 10 need to be performed before the light beam is incident on the display element 201. As Figure 1 shown, in order to implement operations such as shaping and homogenizing the light beam, a beam adjustment lens group 103, a light homogenizing element 202, a focusing lens group 203, etc. need to be provided.

[0058] Among them, the beam adjustment lens group 103 can adopt a telescopic lens group and can perform beam reduction processing on the incident light beam; the light homogenizing element 202 can adopt a light pipe or a fly-eye lens group. In Figure 1 it is shown by taking the light homogenizing element 202 adopting a fly-eye lens group as an example. The light homogenizing element 202 is used to homogenize the incident light beam. In order to meet the spot size and incident angle of the incident display element 201, a focusing lens group 203 also needs to be provided to perform focusing processing on the light beam. After focusing, the projection light beam can be incident on the display element 201 for modulation.

[0059] As Figure 1 shown, in the projection device, in order to make the spot incident on the DMD meet the requirements, multiple groups of lenses and light homogenizing elements need to be provided in the optical path, which results in a relatively large volume of the entire optical engine and cannot meet the requirements of miniaturization of the optical system.

[0060] In view of this, in the embodiments of the present invention, by providing a diffractive optical element in the projection device and utilizing the characteristics of small size and high efficiency of the diffractive optical element, multiple groups of lenses and light homogenizing elements provided in the optical path can be omitted, thereby reducing the volume of the projection device.

[0061] Specifically, as Figure 2 shown, the projection device includes: a laser light source, a focusing lens 203', a light homogenizing element 205, a total reflection prism 204, a display element 201, and a projection lens 30.

[0062] Laser light sources have the advantages of good monochromaticity, high brightness, long lifespan, etc., and are relatively ideal light sources. With the improvement of laser power to meet the requirements of industrial applications, lasers are gradually being used as light sources for illumination. Lasers are used as projection light sources in projection devices, gradually replacing mercury lamp illumination, and compared with LED light sources, lasers are also widely used due to their small optical expansion amount and high brightness.

[0063] In the embodiments of the present utility model, a diffractive optical element 104 is applied in the laser light source. Since the diffractive optical element 104 is sensitive to the wavelength and incident angle of incident light, and laser has a narrow full-width at half-maximum and high collimation, it is very suitable for use with laser light sources.

[0064] As Figure 2 shown, the laser light source can emit three-color laser, and specifically can be divided into three types of light-emitting regions 101, namely the first light-emitting region 101-1, the second light-emitting region 101-2, and the third light-emitting region 101-3. The three types of light-emitting regions are used to emit lasers of different wavelengths. Among them, the three types of light-emitting regions 101 can be different regions in a laser that can emit three-color laser, or can be three lasers that emit lasers of different colors, which is not limited here.

[0065] The laser light source further includes three diffractive optical elements 104, which are arranged on the light-emitting side of the three types of light-emitting regions 101 and are arranged in one-to-one correspondence with the three types of light-emitting regions 101. Diffractive Optical Elements (abbreviated as DOE) 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 of its surfaces. The size of the microstructures is usually in the micron order. These microstructures can change the phase of incident light, thereby changing the propagation path of light at the microscopic scale and realizing the shaping and homogenization of the light beam.

[0066] The shaping principle of the diffractive optical element 104 for the light beam is mainly based on the phenomena of light diffraction and interference. When the light beam passes through the diffractive optical element 104, the microstructures of the diffractive optical element 104 will cause the propagation direction of light to change. When different light waves meet in space, an interference phenomenon of mutual superposition will occur. By precisely designing the microstructures of the diffractive optical element 104, the effects of diffraction and interference can be controlled, thereby realizing the shaping of the light beam.

[0067] Since the diffractive optical element 104 is arranged on the light-emitting side of the light-emitting region of the laser light source, it can play a role in shaping and homogenizing the incident laser beam. Therefore, it is not necessary to set up more optical elements in the projection device to shape and homogenize the laser beam. As Figure 2As shown, the laser beams emitted from the three types of light-emitting regions 101 of the laser light source are diffracted by the diffractive optical element 104 and then combined. The combined light beam only needs to be focused on the display element 201 by the focusing lens 203', and the projection lens projects and images the display image modulated by the display element 201, thereby obtaining a projection image with a larger size.

[0068] As Figure 2 shown, by arranging the diffractive optical element 104 in the laser light source, diffracting and shaping the lasers with different wavelengths before combining the light, only focusing the combined light beam on the display element after combining the light can meet the illumination requirements of the display element. Multiple groups of optical devices such as lenses and light homogenizing elements can be omitted in the optical path of the optical engine, reducing the overall volume of the optical engine, making the optical path more concise, and meeting the miniaturization design of the projection device.

[0069] In the embodiment of the present utility model, a laser light source using a laser that can emit three-color lasers is taken as an example for illustration. As Figure 3 and Figure 4 shown, the laser light source may include a plurality of laser chips arranged in an array, divided into a plurality of first laser chips a1, a plurality of second laser chips a2, and a plurality of third laser chips a3; wherein, the first laser chip a1 is located in the first light-emitting region 101-1, the second laser chip a2 is located in the second light-emitting region 101-2, and the third laser chip a3 is located in the third light-emitting region 101-3.

[0070] In some embodiments, as Figure 3 shown, the laser light source may adopt an MCL laser, and the first laser chip a1, the second laser chip a2, and the third laser chip a3 are arranged in a 4×7 matrix along the first direction x and the second direction y. The numbers of the first laser chip a1 and the second laser chip a2 are both less than the number of the third laser chip a3. The first laser chip a1 is arranged in a row along the second direction y, the second laser chip a2 is arranged in a row along the second direction y, and the third laser chip a3 is arranged in two rows along the second direction y.

[0071] In some embodiments, as Figure 4 shown, the laser light source may adopt an NUBB laser or a NUMB laser, 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 numbers of the first laser chip a1 and the second laser chip a2 are both less than the number of the third laser chip a3. The first laser chip a1 and the second laser chip a2 are arranged in a row along the second direction y, and the third laser chip a3 is arranged in a row along the second direction y.

[0072] The above lasers are all semiconductor lasers. Due to problems such as materials and efficiency, usually a larger number of red laser chips need to be set. Therefore, the above third laser chip a3 can be a red laser chip, the second laser chip a2 can be a green laser chip, and the first laser chip a1 can be a blue laser chip.

[0073] It should be noted that Figure 3 and Figure 4 the arrangement mode of the laser chips shown is only for example. In practical applications, the types of laser chips included in the laser, the wavelengths of the lasers emitted by each type of laser chip, the number and arrangement mode of each type of laser chip are not limited.

[0074] Taking Figure 3 the laser shown as an example, as Figure 5 shown, the three diffractive optical elements respectively corresponding to the three light-emitting regions 101 are the first diffractive optical element 104-1, the second diffractive optical element 104-2, and the third diffractive optical element 104-3. Among them, the first diffractive optical element 104-1 is correspondingly arranged with the first light-emitting region 101-1, the second diffractive optical element 104-2 is correspondingly arranged with the second light-emitting region 101-2, and the third diffractive optical element 104-3 is correspondingly arranged with the second light-emitting region 101-3. The laser beam emitted from each light-emitting region still has a certain divergence angle. As the optical path increases, the divergence degree of the laser beam becomes larger, and the formed spot size will also be larger. Therefore, in the embodiment of the present invention, the diffractive optical element can be arranged close to the corresponding light-emitting region, so as to control the size of the diffractive optical element from being too large.

[0075] Figure 6 It is a schematic diagram of the imaging principle provided by the embodiment of the present invention. In order to highlight the imaging principle of the light beam, some optical elements in the projection device are omitted.

[0076] As Figure 6 shown, for each light-emitting region, the laser beam yb emitted by it is incident on the diffractive optical element 104. The diffractive optical element can shape and image it. The shaped and imaged light beam is then focused at the position of the display element through the focusing lens 203', and finally a diffractive spot CB is formed at the position of the display element. The diffractive spot CB is a rectangular spot with uniform energy distribution. The display element is usually also rectangular, and the long side of the rectangular spot is parallel to the long side of the display element, and the short side of the rectangular spot is parallel to the short side of the display element. The rectangular spot will cover the effective area of the display element, so that the display element modulates the incident light to form a display image.

[0077] At the same time, as Figure 6As shown, due to the process limitations of the diffractive optical element 104, the phase of the microstructure on its surface is close to continuous change but not continuously changing under ideal conditions. Therefore, a part of the light rays are not diffracted after passing through the diffractive optical element 104 and directly pass through the focusing lens 203' for imaging, forming a bright spot at the center position of the displayed diffracted light spot CB, which is called the zero-order light spot 0B. To distinguish the light rays forming the diffracted light spot CB and the zero-order light spot 0B, the light rays forming the diffracted light spot CB are called diffracted light, and the light rays forming the zero-order light spot 0B are called zero-order light. The zero-order light spot 0B will affect the uniformity of the energy distribution within the effective area of the display element, thereby reducing the image quality.

[0078] To overcome the above problems, in the embodiments of the present utility model, when designing the diffractive optical element 104, an angular offset phase can be added, so that there is a certain angle between the diffracted light and the zero-order light after the laser beam passes through the diffractive optical element 104. Furthermore, when irradiating the display element, the diffracted light spot CB and the zero-order light spot 0B are separated from each other. The diffracted light spot CB covers the effective area of the display element, while the zero-order light spot 0B does not overlap with the effective area of the display element, thereby avoiding the adverse effects of the zero-order light spot 0B on the image.

[0079] Specifically, as Figure 7 shown, the laser beams emitted from the three types of light-emitting regions 101 of the laser light source pass through their corresponding diffractive optical elements 104 and then enter the light combining component 102 for light combination.

[0080] Still taking the Figure 3 shown laser as an example, when combining the Figure 3 shown laser, the light combining component 102 may include three light combining members arranged in parallel with each other, specifically the first light combining member 102-1, the second light combining member 102-2, and the third light combining member 102-3. Among them, the first light combining member 102-1 is correspondingly arranged for the first light-emitting region 101-1, the second light combining member 102-2 is correspondingly arranged for the second light-emitting region 101-2, and the third light combining member 102-3 is correspondingly arranged for the third light-emitting region 101-3. The first light combining member 102-1 is used to reflect the laser light emitted from the first light-emitting region 101-1 to the second light combining member 102-2. The second light combining member 102-2 is used to combine the laser light emitted from the first light-emitting region 101-1 and the laser light emitted from the second light-emitting region 101-2 and emit it to the third light combining member 102-3. Finally, the third light combining member 102-3 combines 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.

[0081] In specific implementation, the first light combining element 102-1 may adopt a reflecting mirror, and the second light combining element 102-2 and the third light combining element 102-3 may adopt dichroic mirrors, which are not limited herein.

[0082] Before the laser beams emitted from the three types of light-emitting regions 101 are incident on the light combining assembly 102, they are all shaped by the corresponding diffractive optical element 104. After diffraction by the diffractive optical element 104, the beam center of the diffracted light is offset by a set angle θ with respect to the beam center of the zero-order light.

[0083] Since the laser has different divergence angles in different directions, the laser emitted from each laser chip will form an elliptical spot in the far field. The light-emitting region 101 includes multiple laser chips. Regarding the laser emitted from each laser chip as a sub-beam, therefore, when the multiple sub-beams emitted from the light-emitting region 101 are incident on the diffractive optical element 104, they are multiple elliptical spots. When exiting the diffractive optical element 104 after diffraction by the diffractive optical element 104, the diffracted light becomes multiple rectangular spots. The edge of each rectangular spot is relatively blurred, and the beam centers of the sub-beams of the diffracted light are parallel to each other. During the process of being incident on the focusing lens 203', the sub-beams gradually diverge. After being focused by the focusing lens 203', the beam centers of the sub-beams of the diffracted light are no longer parallel and converge. When incident on the display element, it becomes a rectangular spot with a larger size, and the edge of the rectangular spot becomes sharp. At the same time, the zero-order light emitted from the diffractive optical element 104 also has multiple sub-beams. Similarly, the sub-beams of the zero-order light will also converge into a clear zero-order spot at a position near the display element.

[0084] Due to the special phase design of the diffractive optical element, the diffractive optical element causes the diffracted light to have an offset of a set angle, so that the diffracted light after the three types of light-emitting regions 101 pass through the corresponding diffractive optical element 104 is focused by the focusing lens 203' at the position of the display element 201, forming three diffracted spots. The three diffracted spots are all rectangular spots and have different colors. The long sides of the three-color rectangular spots are parallel to each other, and the short sides are parallel to each other. The three-color rectangular spots overlap, and the centers of the three-color rectangular spots coincide. The overlapping area of the three-color rectangular spots can cover the effective area of the display element. The zero-order light after the three types of light-emitting regions 101 pass through the corresponding diffractive optical element 104 is focused by the focusing lens 203' at a position outside the display element 201, thus avoiding the zero-order light from forming a zero-order spot within the effective area of the display element.

[0085] As Figure 7 shown, the light combining element (light combining assembly 102) is inclined with respect to the light-emitting surface (the plane formed by the first direction x and the second direction y) of the light-emitting region 101, so that the incident angles of the diffracted light and the zero-order light emitted from the diffractive optical element 104 when incident on the light combining element are different. Then, asFigure 8 As shown, there is also a set angle θ between the beam center of the diffracted light reflected by the light combining member and the beam center of the zero-order light, and this set angle satisfies:

[0086] θ = arctan(df);

[0087] Where θ represents the set angle formed by the beam center of the diffracted light and the beam center of the zero-order light, d represents the distance between the center of the diffracted light spot and the center of the zero-order light spot, and f represents the focal length of the focusing lens.

[0088] The above set angle θ is the theoretical design value. Due to problems such as lens aberration and structural tolerances, in actual applications, the deviation angle of the diffracted light is within a range and can be within the range of [0.9θ - 1.1θ].

[0089] In some embodiments, as Figure 7 shown, the angle between the light combining member (light combining assembly 102) and the light emitting surface of the light emitting area 101 (the plane formed by the first direction x and the second direction y) is 45°. Then, when the zero-order light is incident on the light combining member, the incident angle is 45°, and the incident angle of the diffracted light incident on the light combining member is As Figure 8 shown, the beam center of the zero-order light after being reflected by the light combining member coincides with the first direction x, and the angle between the beam center of the diffracted light and the first direction x is θ. At this time, as Figure 7 shown, it is necessary to rotate the focusing lens 203' and the optical elements behind its optical path as a whole by an angle θ so that the optical axis of the optical system coincides with the beam center of the diffracted light.

[0090] In some embodiments, as Figure 9 shown, the angle between the light combining member (light combining assembly 102) and the light emitting surface of the light emitting area 101 (the plane formed by the first direction x and the second direction y) is Then the incident angle of the diffracted light incident on the light combining member is 45°, and the incident angle of the zero-order light incident on the light combining member is As Figure 10 shown, the beam center of the diffracted light after being reflected by the light combining member coincides with the first direction x, and the angle between the beam center of the zero-order light and the first direction x is θ. At this time, as Figure 9 shown, since the angle of the light combining member is rotated in advance, the optical axes of the focusing lens 203' and the subsequent optical elements are all parallel to the first direction, which is more conducive to the design of the optical system and the appearance aesthetics, can reduce the difficulty of structural design, and is conducive to realizing the miniaturization of the optical engine.

[0091] As Figure 7 and Figure 9As shown, a total reflection prism 204 is usually further provided in the projection device. The total reflection prism 204 is located between the focusing lens 203' and the display element 201, and is used to separate the illumination optical path and the imaging optical path. The total reflection prism 204 reflects the outgoing light of the focusing lens 203' to the display element 201, and transmits the modulated outgoing light of the display element 201 to the projection lens 30 for projection imaging.

[0092] As Figure 11 shown, a light shielding sheet p is usually provided around the display element 201. The light shielding sheet p can absorb stray light and prevent the stray light from being reflected into the optical system to affect image display. In the embodiment of the present invention, after the diffracted light and the zero-order light enter the total reflection prism, they are both reflected by the total reflection prism, and the diffracted light is totally reflected to the display element, while the zero-order light is totally reflected to the light shielding sheet p around the display element, thereby preventing the zero-order light from being reflected into the optical system to affect image display.

[0093] Specifically, as Figure 11 shown, the total reflection prism 204 includes an incident light surface 204a and a total reflection surface 204b; the outgoing light of the focusing lens enters the total reflection prism from the incident light surface 204a, and is totally reflected by the total reflection surface 204b and then exits to the display element 201.

[0094] In order to make both the diffracted light and the zero-order light be totally reflected by the total reflection surface 204b of the total reflection prism, the critical angle of the total reflection prism needs to be considered. If the refractive index of the total reflection prism 204 is n, then the critical angle for total reflection occurring on the total reflection surface of the total reflection prism Both the diffracted light and the zero-order light are totally reflected on the total reflection surface, then it is necessary to satisfy:

[0095] α4 - θ ≥ α0;

[0096] According to the fact that the sum of the interior angles of a triangle is 180°, it can be deduced that: α4 = α2 + α3. If the F number of the optical system is F, then From this, it can be deduced that:

[0097]

[0098] According to the law of refraction: sinα1 = nsinα3. Substituting it into the above formula, we can get:

[0099]

[0100] Among them, α1 represents the incident angle of the diffracted light when it enters the incident light surface of the total reflection prism, α2 represents the included angle between the incident light surface and the total reflection surface of the total reflection prism, n represents the refractive index of the total reflection prism, and F represents the F number of the optical system.

[0101] By designing the diffractive optical element and the total reflection prism to satisfy the above formula, it can be ensured that both the diffracted light and the zero-order light emitted from the diffractive optical element can undergo total reflection on the total reflection surface of the total reflection prism, and the diffracted light can be incident on the display element, while the zero-order light is incident on the light-shielding sheet around the display element.

[0102] In some embodiments, as Figure 12 shown, the projection device further includes a light homogenizing element 205 located between the focusing lens 203' and the total reflection prism 204. The light homogenizing element 205 is used to homogenize the laser beam, making the laser beam incident on the display element more uniform and avoiding the formation of laser speckles.

[0103] In specific implementation, the light homogenizing element 205 can adopt at least one of a diffuser, a fly-eye lens, a diffuser wheel, or a moving diffuser. For example, the light homogenizing element 205 can adopt a diffuser. The diffuser is located close to the total reflection prism 204. The diffuser can be in a stationary state or a moving state. The diffuser can adopt a flat plate dispersed with diffusing particles or frosted glass, which itself has a scattering effect on the incident light. Coupled with its high-frequency movement, the polarization direction of the emitted laser can be made disordered, thus improving the problem of laser speckles. The diffuser can move along the long side direction of the rectangular diffracted light spot or can perform a flipping movement along the diagonal direction, which is not limited here. Or, the light homogenizing element 205 can also adopt a diffuser wheel. The diffuser wheel is connected to a driving device and can rotate, so as to diversify the polarization direction of the laser and improve the problem of laser speckles.

[0104] Finally, it should be noted that when the three light-emitting regions of the laser light source can be different regions of the same laser, the diffractive optical element can adopt one element and perform a separate partition design for the corresponding different light-emitting regions. When the three light-emitting regions of the laser light source are three lasers emitting different wavelengths respectively, three diffractive optical elements can be applied.

[0105] The microstructures on the surface of the diffractive optical element 104 are fabricated by semiconductor processing technology. The surface topography, size, and refractive index of the diffractive optical element 104 will all affect the phase of light. In order to obtain an image with uniform energy distribution and clear contour at the position of the display element 201, it is necessary to finely design the phase of the diffractive optical element according to the input parameters of the incident light beam and the output parameters of the emitted light beam.

[0106] Among them, the input parameters of the incident light beam can include: the wavelength, beam quality, waist radius, and intensity distribution, etc. when the laser beams emitted from each laser chip are incident on the corresponding regions of the corresponding diffractive optical element; the input parameters of the emitted light beam can include: the size of the light spot, the emission distance, the diffraction order, and the intensity distribution, etc. when the laser beam is incident on the position of the display element.

[0107] The design of diffractive optical elements can adopt algorithms such as the GS algorithm and the Y-G algorithm to calculate the phase of the diffractive optical element. From the periodicity of the phase, the phase of the diffractive optical element can be compressed to [0, 2π]. However, limited by the current processing ability, it is impossible to process microstructures with continuous phases. Therefore, the continuous phase can be subdivided into stepped microstructures with different heights.

[0108] The following specifically introduces the design idea of the phase distribution of diffractive optical elements designed by the GS algorithm. When the amplitude distributions of the input field (incident laser beam) and the target field (laser beam at the position of the display element) are known, and the initial phase can be selected as a random phase, perform Fourier transform on the initial phase and the input field amplitude to obtain the complex amplitude in the frequency domain; extract the phase in the frequency-domain complex amplitude, and then add the amplitude of the target field; perform inverse Fourier transform on the obtained complex amplitude to obtain the complex amplitude in the spatial domain, extract the phase in the complex amplitude, and then add the amplitude of the input field to obtain a new complex amplitude; perform Fourier transform on the new complex amplitude to obtain the complex amplitude in the frequency domain. Continuously iterate the above Fourier transforms, and finally the phase of the complex amplitude in the spatial domain extracted is the phase of the diffractive optical element.

[0109] In addition, other algorithms can also be used to design the phase of diffractive optical elements. In the embodiments of the present utility model, only the GS algorithm is taken as an example, and in practical applications, a reasonable method can be selected according to requirements to design diffractive optical elements.

[0110] Based on the same inventive concept, the embodiments of the present utility model also provide a projection system, as Figure 13 shown. The projection system includes a projection device 1 and a projection screen 2.

[0111] The projection screen 2 is located on the light-emitting side of the projection device 1, and the audience faces the projection screen 2. The projection device 1 emits projection light, and the projection light is incident on the projection screen 2 and then exits in the direction of the audience through the projection screen 2, so that the audience can view the projection image.

[0112] When the projection device 1 and the audience are on the same side of the projection screen 2, this projection system is called a front-projection system. When the projection device 1 and the audience are on both sides of the projection screen 2 respectively, this projection system is called a rear-projection system. In the front-projection system, the projection device 1 emits projection light to the projection screen 2, and the projection screen 2 reflects the projection light to the audience, so that the audience can view the projection image. In the rear-projection system, the projection device 1 emits projection light to the projection screen 2, and the projection light passes through the projection screen 2 and exits to the audience, so that the audience can view the projection image.

[0113] The projection device 1 can adopt any of the above projection devices. The projection device includes a laser light source, an illumination system, and a projection lens. Among them, the laser light source includes three types of light-emitting regions and three diffractive optical elements, and the wavelengths of the laser light emitted from the three types of light-emitting regions are different. The illumination system includes a focusing lens, a light homogenizing element, a total reflection prism, and a display element. The display element can modulate the incident laser to form a display image, and then the display image is incident on the projection lens for projection imaging.

[0114] The wavelengths of the laser light emitted from each light-emitting region of the laser light source are different. When designing the diffractive optical element, the diffracted light offset phase is increased, so that the diffracted light of the laser beam emitted from each light-emitting region is offset by a set angle relative to the zero-order light when it exits after being diffracted by the diffractive optical element. Thus, the diffracted light spot and the zero-order light spot formed by the diffracted light of the diffractive optical element on the display element after passing through the focusing lens can be separated from each other. The diffracted light spot covers the effective region of the display element, while the zero-order light spot does not overlap with the display element, thereby avoiding the adverse effects of the zero-order light spot on the projection image.

[0115] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0116] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A projection device, characterized in that, Comprising: A laser light source for emitting three-color lasers; the laser light source includes: three types of light-emitting regions and three diffractive optical elements corresponding to the three types of light-emitting regions one by one, and the wavelengths of the lasers emitted by the three types of light-emitting regions are different; A focusing lens located on the light-emitting side of the diffractive optical element; A display element located on the side of the focusing lens facing away from the laser light source, for modulating the incident laser beam to form a display image; Wherein, the laser beam emitted from the light-emitting region forms a diffractive spot and a zero-order spot when incident on the display element after passing through the diffractive optical element and the focusing lens, the diffractive spot covers the effective area of the display element, and the zero-order spot is separated from the diffractive spot.

2. The projection device according to claim 1, characterized in that, Further comprising: A light-combining component located on the side of the three diffractive optical elements facing away from the three types of light-emitting regions, for combining the laser beams of three wavelengths and reflecting them to the focusing lens; The three diffractive spots formed when the laser beams emitted from the three types of light-emitting regions are incident on the display element after passing through the corresponding diffractive optical elements, the light-combining component and the focusing lens are all rectangular spots; the centers of the three rectangular spots coincide and there is an overlapping area, and the overlapping area covers the effective area of the display element.

3. The projection device according to claim 2, wherein The light-combining component includes: three light-combining members arranged in parallel with each other and corresponding to the three types of light-emitting regions one by one; the light-combining member is inclined with respect to the light-emitting surface of the corresponding light-emitting region.

4. The projection device according to claim 3, characterized in that, The diffracted light after passing through the diffractive optical element and the focusing lens forms the diffractive spot, and the zero-order light after passing through the diffractive optical element and the focusing lens forms the zero-order spot light; There is a set angle between the beam center of the diffracted light and the beam center of the zero-order light, and the set angle satisfies: θ = arctan(d / f); Wherein, θ represents the set angle formed by the beam center of the diffracted light and the beam center of the zero-order light, d represents the distance between the center of the diffractive spot and the center of the zero-order spot, and f represents the focal length of the focusing lens.

5. The projection device according to claim 4, wherein The included angle between the light-combining member and the light-emitting surface of the corresponding light-emitting region is 45°; The beam center of the zero-order light coincides with the first direction, and the included angle between the beam center of the diffracted light and the first direction is θ; the first direction is parallel to the light-emitting surface of the light-emitting region and forms a 45° angle with the light-combining member.

6. The projection device according to claim 4, wherein The included angle between the light combining member and the light emitting surface of the corresponding light emitting region is The beam center of the diffracted light coincides with the first direction, and the included angle between the beam center of the zero-order light and the first direction is θ; the first direction is parallel to the light-emitting surface of the light-emitting area and forms an included angle with the light combining element.

7. The projection device according to any one of claims 4 to 6, characterized in that Further comprising: A total reflection prism located between the focusing lens and the display element; the total reflection prism includes an incident light surface and a total reflection surface; the light emitted from the focusing lens is incident into the total reflection prism from the incident light surface, and is totally reflected on the total reflection surface and then emitted to the display element; The incident angle of the diffracted light incident on the incident light surface of the total reflection prism satisfies: Wherein, α1 represents the incident angle of the diffracted light incident on the incident light surface of the total reflection prism, α2 represents the included angle between the incident light surface and the total reflection surface of the total reflection prism, n represents the refractive index of the total reflection prism, and F represents the F-number of the optical system.

8. The projection device according to claim 7, characterized in that, Light-shielding sheets are arranged around the display element; The diffracted light is incident on the display element, and the zero-order light is incident on the light shield.

9. The projection device according to claim 7, characterized in that, Further included are: a light homogenizing element, which is located between the focusing lens and the total reflection prism and is used for homogenizing the laser beam; The light homogenizing element adopts at least one of a diffuser sheet, a fly-eye lens, a diffuser wheel or a moving diffuser.

10. A projection system, characterized in that, Comprising: a projection device, which is the projection device according to any one of claims 1 to 9; a projection screen, which is located on the light-emitting side of the projection device.

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