Lighting systems and projection equipment

Abstract

This application discloses an illumination system and a projection device, belonging to the field of laser technology. The illumination system includes a digital micromirror device, a prism assembly, a light-blocking plate, and a projection lens arranged sequentially along the optical path of the illumination system. The light-blocking plate includes an opening area and a blocking area. The digital micromirror device processes the received illumination beam and reflects it out. The imaging beam output by the digital micromirror device when its mirror is in the open state is guided to the prism assembly, and the imaging beam can pass through the prism assembly and the opening area of ​​the light-blocking plate to reach the projection lens. The blocking area of ​​the light-blocking plate can block non-imaging beams output by the digital micromirror device when its mirror is in the closed state from reaching the projection lens. In other words, the light-blocking plate can reduce the amount of non-imaging beams reaching the projection lens, thereby improving the contrast of the projected display image and solving the problem of poor image quality in related technologies, thus improving the overall quality of the projected display image.

Description

Technical Field

[0001] This application relates to the field of laser technology, and in particular to a lighting system and a laser projection device. Background Technology

[0002] Laser projection display technology is a new type of projection display technology on the market. Compared with LED projection products, laser projection display technology has the advantages of clearer imaging, more vibrant colors, and higher brightness. These significant features have gradually made laser projection display technology another mainstream development direction in the market. A digital micromirror device (DMD) consists of multiple mirrors that can rotate between two positions: an on position and a closed position. The beam emitted by the DMD can be controlled by rotating the mirrors. The size of the DMD directly affects the display effect of the laser projection device. The larger the DMD, the more pixels it has, resulting in a more detailed display image. Simultaneously, it reflects more light, resulting in higher brightness.

[0003] An illumination system includes a DMD and a prism, wherein the prism is required to allow both the imaging beam and the non-imaging beam of the DMD to be incident on the prism, so as to guide the imaging beam to a projection lens while preventing the non-imaging beam from being incident on the projection lens.

[0004] The quality of the projected image from the aforementioned lighting system is poor. Summary of the Invention

[0005] This application provides a lighting system and a projection device. The lighting system includes: a digital micromirror device, a prism assembly light-blocking plate, and a projection lens arranged sequentially along the optical path of the lighting system; The prism assembly includes a first light-incident surface and a first light-outcident surface. The digital micromirror device (DMM) is located outside the first light-incident surface, and the light-blocking plate is located outside the first light-outcident surface. The DMM is used to process the received light beam and guide it to the first light-incident surface of the prism assembly. The light-blocking plate includes an opening area and a blocking area. The size of the opening area is greater than or equal to the maximum size of the light spot on the plane of the light-blocking plate when the reflector in the DMM is in the open state. This allows the imaging light beam to pass through the opening area and be directed toward the projection lens. The blocking area of ​​the light-blocking plate is used to block the non-imaging light beam output by the reflector in the DMM when it is in the closed state from being directed toward the projection lens.

[0006] Optionally, the prism assembly includes a first prism, which is formed by a first light-incident surface, a first light-exiting surface, and a bottom surface, wherein the first light-incident surface and the first light-exiting surface are perpendicular to each other. The non-imaging beam includes a first beam that is directed toward the first light-incident surface of the prism assembly and emitted through the bottom surface of the first prism, and a second beam that is directed from the digital micromirror toward the light-incident port. The blocking area of ​​the light-blocking plate includes a first blocking area for blocking the first beam and a second blocking area for blocking the second beam.

[0007] Optionally, the first prism is used to receive the imaging beam through the first incident surface and guide the imaging beam to the bottom surface, and the bottom surface reflects the imaging beam to the first exit surface to output the first prism. The size of the first incident surface is greater than or equal to the size of the light spot on the plane where the imaging beam illuminates the bottom surface.

[0008] Optionally, the digital micromirror device is rectangular, and the short side of the digital micromirror device is parallel to the first light-incident surface and perpendicular to the first light-outceasing surface.

[0009] Optionally, the first incident surface satisfies the formula: P≥2 L tanθ+W DMD ; Where P is the side length of the first incident surface, L is the distance from the mirror of the digital micromirror device to the first prism; θ is the numerical aperture angle of the illumination system, and W... DMD The width of the short side of the digital micromirror device; The numerical aperture angle of the lighting system satisfies the formula: θ=arcsin(1 / 2) F); where F is the F-number of the lighting system.

[0010] Optionally, the prism assembly further includes a second prism and a flat glass plate. The second prism is surrounded by a second light-incident surface, a second light-exit surface, and a curved surface. The second light-exit surface is opposite to one side of the flat glass plate, and the bottom surface of the first prism is opposite to the other side of the flat glass plate. The second light-incident surface is used to receive the light beam and guide the light beam to the curved surface, and the curved surface is used to reflect the light beam toward the second light-exit surface.

[0011] Optionally, the lighting system further includes a galvanometer assembly located between the digital micromirror device and the prism assembly.

[0012] Optionally, the illumination system further includes a light homogenizing component and a beam collimating magnifying lens group. The light homogenizing component is used to process the received light beam and guide it to the beam collimating magnifying lens group, and the beam collimating magnifying lens group is used to guide the light beam to the prism component.

[0013] Optionally, the beam collimating magnifying lens group includes a first lens, a second lens, and a third lens arranged sequentially along the optical path direction, wherein the principal optical axis of the first lens is rotated by a first angle in a counterclockwise direction from a state parallel to the principal optical axis of the beam homogenizing component.

[0014] The beneficial effects of the technical solutions provided in this application include at least the following: An illumination system comprising a digital micromirror device (DMM), a prism assembly, a light-blocking plate, and a projection lens is provided. The light-blocking plate includes an opening area and a blocking area. The DMM processes the received light beam and reflects it, guiding the imaging beam output by the DMM when its mirror is in the open state to the prism assembly. The imaging beam can pass through the prism assembly and the opening area of ​​the light-blocking plate to the projection lens. The blocking area of ​​the light-blocking plate can block the non-imaging beam output by the DMM when its mirror is in the closed state from reaching the projection lens. In other words, the light-blocking plate can reduce the non-imaging beam reaching the projection lens, thereby improving the contrast of the projected display image and solving the problem of poor image quality in related technologies, thus achieving the effect of improving the image quality of the projected display. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a lighting system. Figure 2 This is a schematic diagram of another lighting system; Figure 3 This is a schematic diagram of the structure of a lighting system shown in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a light-blocking plate shown in an embodiment of this application; Figure 5 This is a schematic diagram of the optical path of a lighting system shown in an embodiment of this application; Figure 6 yes Figure 2 A schematic diagram of the digital micromirror device and the first prism in the lighting system shown; Figure 7 This is a schematic diagram of a post-working distance structure shown in an embodiment of this application; Figure 8 This is a schematic diagram of another lighting system provided in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of a projection device provided in an embodiment of this application.

[0017] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0019] Digital micromirror devices (DMDs) can be viewed as optical switches composed of numerous micromirrors. The switching is achieved by rotating these micromirrors; the number of mirrors is determined by the display resolution, with each small mirror corresponding to a pixel. The micromirror is the smallest working unit and is crucial to its performance. Despite their extremely small size, micromirrors possess a complex mechanical structure unlike liquid crystal displays (LCDs). Each micromirror has an independent support frame and deflects around a hinged axis by positive or negative n degrees (n > 0). Two electrodes are positioned at the two corners of each micromirror, allowing voltage control of its deflection.

[0020] Micromirrors work by reflecting light. When the micromirror is in the on state (meaning it is deflected by +n degrees), the incident angle of the incident light (light source) reaches n degrees, and the reflection angle also reaches n degrees (the sum of the two is 2n degrees). At this time, the lens can receive the maximum energy of light. When the micromirror is in the off state (meaning it is deflected by -n degrees), the lens receives the minimum energy of light and has the lowest brightness.

[0021] Figure 1 This is a schematic diagram of a lighting system in related technologies. The lighting system includes an illumination mirror group 111, a reverse total internal reflection prism 112, and a digital micromirror device 113.

[0022] After the light beam S1 exits from the illumination mirror group 111, it passes through the reverse total internal reflection prism 112 and is incident on the digital micromirror device 113. The long-side incident mode of the digital micromirror device 113 refers to the fact that the longer side of the digital micromirror device 113 receives the incident light. The imaging beam S11 processed by the digital micromirror device 113 enters the reverse total internal reflection prism 112 and then exits from the reverse total internal reflection prism 112 to the projection lens 114. The non-imaging beam S12 processed by the digital micromirror device 113 also enters the reverse total internal reflection prism 112 and exits from the reverse total internal reflection prism 112 to the optomechanical illumination system.

[0023] However, since the digital micromirror device 113 cannot allow all non-imaging beams to enter the reverse total internal reflection prism 112, some of the non-imaging beams S12 enter the projection lens 114. Furthermore, due to the different refractive indices of beams of different colors, some of the non-imaging beams S12 emitted through the reverse total internal reflection prism 112 enter the projection lens, resulting in low contrast of the projected image.

[0024] Figure 2 This is a schematic diagram of another lighting system in the related art, which includes an illumination mirror group 121, a reverse total internal reflection prism 122, and a digital micromirror device 123. When the light beam S1 exits from the illumination mirror group 121, it passes through the reverse total internal reflection prism 122 and then enters the digital micromirror device 123. Compared to the lighting systems in the related art described above, the reverse total internal reflection prism 122 in this lighting system is larger, allowing the non-imaging light beam S12 to undergo total emission at the first light-emitting surface of the reverse total internal reflection prism 122 and exit from the bottom surface, thereby reducing the amount of non-imaging light beam S12 output by the digital micromirror device 123 that enters the projection lens 114.

[0025] However, the large size of the reverse total internal reflection prism in this lighting system leads to an increased working distance behind the projection lens, resulting in a larger lens size and consequently a larger overall size of the lighting device, thus making the entire projection equipment larger in size.

[0026] This application provides a lighting device and a laser projection device that can solve the problems in the aforementioned related technologies.

[0027] like Figure 3 As shown, Figure 3 This application illustrates an illumination system for viewing a digital micromirror device (DMV) from a plane parallel to the DMV. The illumination system includes a DMV 21, a prism assembly 22, a light-blocking plate 23, and a projection lens arranged sequentially along the optical path of the illumination system. The projection lens may include an incident lens 24.

[0028] The prism assembly 22 includes a first light-incident surface B1 and a first light-exiting surface B2. The digital micromirror device 21 is located outside the first light-incident surface B1, and the light-blocking plate 23 is located outside the first light-exiting surface B2. The digital micromirror device 21 is used to process the received light beam and guide it to the first light-incident surface B1 of the prism assembly.

[0029] like Figure 4 As shown, Figure 4This is a schematic diagram of a light-blocking plate according to an embodiment of this application. The light-blocking plate 23 includes an opening area 231 and a blocking area 232. The size of the opening area 231 is greater than or equal to the maximum size of the light spot on the plane of the light-blocking plate 23 when the imaging beam output by the mirror in the digital micromirror device is in the open state. This allows the imaging beam to pass through the opening area 231 and be directed toward the projection lens. The blocking area 232 of the light-blocking plate 23 is used to block the non-imaging beam output by the mirror in the digital micromirror device when it is in the closed state from being directed toward the projection lens. In other words, the light-blocking plate can reduce the non-imaging beam at the projection lens, thereby reducing the impact of the non-imaging beam emitted by the digital micromirror device on the contrast of the projected display image.

[0030] For example, such as Figure 5 As shown, Figure 5 This is a schematic diagram of the optical path of an illumination system shown in an embodiment of this application. When the reflector in the digital micromirror device 21 is in the open state, the imaging beam S3 output can pass through the opening area and be directed to the light-receiving lens 24 on the lens. When the reflector in the digital micromirror device 21 is in the closed state, the non-imaging beam S4 output can be directed to the blocking area of ​​the light-blocking plate 23, which can reduce the non-imaging beam S4 incident on the light-receiving lens 24, thereby improving the contrast of the projected display image.

[0031] In summary, this application provides an illumination system including a digital micromirror device, a prism assembly, a light-blocking plate, and a projection lens. The light-blocking plate includes an opening area and a blocking area. The digital micromirror device processes the received light beam and reflects it, guiding the imaging beam output by the digital micromirror device when its mirror is in the open state to the prism assembly. The imaging beam can be projected onto the projection lens through the prism assembly and the opening area of ​​the light-blocking plate. The blocking area of ​​the light-blocking plate can block the non-imaging beam output by the digital micromirror device when its mirror is in the closed state from being projected onto the projection lens. In other words, the light-blocking plate can reduce the non-imaging beam projected onto the projection lens, thereby improving the contrast of the projected display image while achieving miniaturization. This solves the problem of poor image quality in related technologies and achieves the effect of improving the quality of the projected display image.

[0032] Optionally, such as Figure 3 As shown, the prism assembly 22 includes a first prism 221, which is formed by a first light-incident surface B1, a first light-outceasing surface B2, and a bottom surface B3. The first light-incident surface B1 and the first light-outceasing surface B2 are perpendicular to each other. For example, the first prism 221 can be a reverse total internal reflection prism (RTIR), which is an isosceles right-angled triangular prism.

[0033] like Figure 5 As shown, the non-imaging beam S4 includes a first beam S41 that strikes the first light-incident surface B1 of the prism assembly 22 and exits through the bottom surface B3 of the first prism 221, and a second beam S42 that strikes the projection lens from the digital micromirror 21. The blocking area 232 of the light-blocking plate includes a first blocking area 2321 for blocking the first beam S41 and a second blocking area 2322 for blocking the second beam S42. The first blocking area 2321 of the light-blocking plate 23 can be used to prevent the first beam S41 from entering the light-incident lens 24, and the second blocking area 2322 of the light-blocking plate 23 can be used to prevent the second beam S42 from entering the light-incident lens 24. In this way, the non-imaging beam at the projection lens can be reduced, thereby reducing the impact of the non-imaging beam emitted by the digital micromirror device on the contrast of the projected display image.

[0034] The light-blocking plate can be located between the prism assembly and the lens. The light-blocking plate can also be connected to a heat sink. When the non-imaging beam emitted from the digital micromirror device hits the light-blocking plate, the heat sink can reduce the temperature of the light-blocking plate and the area around the lens, thereby reducing the temperature drift problem.

[0035] Optionally, such as Figure 5 As shown, the first prism 221 receives the imaging beam S3 through the first incident surface B1 and guides the imaging beam S3 to the bottom surface B3. The bottom surface B3 then reflects the imaging beam S3 towards the first exit surface B2 to output the first prism 221. The size of the first incident surface B1 is greater than or equal to the size of the light spot on the plane where the imaging beam S3 illuminates the first incident surface B1. This ensures that the imaging beam S3 emitted from the digital micromirror device 21 is completely incident on the projection lens.

[0036] Optionally, such as Figure 6 As shown, Figure 6 yes Figure 2 The diagram shows the structure of the digital micromirror device 21 and the first prism 221 in the lighting system. The digital micromirror device 21 is rectangular, and its short side 211 is parallel to the first light-incident surface B1 and perpendicular to the first light-outcrystal surface B2.

[0037] Optionally, such as Figure 6 As shown, the first incident surface B1 satisfies the formula: P≥2 L tanθ+W DMD ; Where P is the side length of the first incident surface B1 (this side length refers to the side length of the side of the first prism 221 that is parallel to the short side of the digital micromirror device 21), L is the distance from the mirror surface of the digital micromirror device 21 to the first prism 221; θ is the numerical aperture angle of the illumination system, and W... DMDThis represents the short side width of the digital micromirror device.

[0038] The numerical aperture angle of the lighting system satisfies the formula: θ=arcsin(1 / 2 F); where F is the F-number of the lighting system.

[0039] It should be noted that the size of the first prism in this embodiment only needs to be designed according to the size of the imaging beam emitted by the digital micromirror device, so that the imaging beam of the digital micromirror device can completely exit the first prism. In contrast, in related technologies, the size of the reverse total internal reflection prism needs to be designed according to the size of both the imaging beam and the non-imaging beam emitted by the digital micromirror device, so that the imaging beam of the digital micromirror device can completely exit the first prism, while the non-imaging beam of the digital micromirror device must be completely incident on the reverse total internal reflection prism and not enter the projection lens. This embodiment can reduce the size of the first prism, thereby reducing the size of the illumination system.

[0040] Optionally, such as Figure 3 As shown, the lighting system also includes a galvanometer assembly 25, located between the digital micromirror device 21 and the prism assembly 22. The illumination beam guided by the prism assembly 22 to the digital micromirror device 21 passes through the galvanometer assembly 25 and is then directed towards the digital micromirror device 21. The digital micromirror device 21 modulates the received beam and guides it to the galvanometer assembly 25. The galvanometer assembly 25 processes the beam emitted from the digital micromirror device 21 and guides it to the prism assembly 22, which then guides it to the lens. The galvanometer assembly 25 may include a flat glass plate, which achieves staggered transmission of the beam through high-frequency vibration. Because the beam is located relatively close to the digital micromirror device, the beam at this location needs to converge on the DMD surface, resulting in a smaller spot size. Therefore, a smaller galvanometer assembly can be selected, thereby reducing the overall size of the lighting system.

[0041] The lighting system in this embodiment can be adapted to larger digital micromirror device valves (e.g., 0.66-inch to 0.98-inch DMDs), thereby enabling the projected image size to reach 100-inch to 150-inch. Based on the cooperation of the galvanometer assembly, the image can achieve a high resolution projection imaging quality of 4K to 8K.

[0042] In laser projectors of related technologies, a galvanometer assembly is typically placed between a reverse total internal reflection prism and a projection lens. The galvanometer assembly may also include a galvanometer structure. When the galvanometer assembly is placed in the illumination system, it provides power to the flat glass, causing it to vibrate and thus improving the resolution of the projection device. The galvanometer structure includes many components such as a circuit board, making it larger than the flat glass. If the galvanometer assembly is placed between the prism assembly and the projection lens, the galvanometer structure interferes with the circuit board of the digital micromirror device. Therefore, to avoid structural interference, the spatial distance in the structure must be increased, leading to an increase in the working distance behind the lens and a larger lens size. However, in the embodiments of this application... Figure 3 As shown, the galvanometer assembly 25 is positioned between the digital micromirror device 21 and the prism assembly 22. When the light beam travels from the prism assembly 22 to the digital micromirror device 21, it is an illumination beam and is therefore unaffected by the vibration of the galvanometer assembly 25. When the light beam enters the digital micromirror device 21 and passes through the galvanometer assembly 25 again to reach the entrance lens 24 of the projection lens, the light beam becomes an imaging beam. At this time, the vibration of the galvanometer assembly 25 can improve the imaging resolution.

[0043] like Figure 7 As shown, Figure 7 This is a schematic diagram illustrating the structure of a rear working distance according to an embodiment of this application. The rear working distance (L) of the lens... BF () refers to the distance from the lens that receives the light beam from the illumination system to the image plane, that is, the distance between the incident lens 24 of the projection lens that receives the light beam provided by the illumination system and the digital micromirror device 21. Figure 7 The sum of the lengths of H1, H2, H3, and H4. When the size of the first prism (RTIR) 221 decreases, the length of H3 decreases accordingly, and the sum of the lengths of H1, H2, H3, and H4 decreases, thereby reducing the rear working distance of the projection lens. Wherein, H1 is the distance from the digital micromirror device 21 to the galvanometer assembly 25; H2 is the distance from the galvanometer assembly 25 to the first prism 221; H3 is the length of the right-angled side of the optical cross-section of the first prism, which is triangular and perpendicular to the plane containing the digital micromirror device 21; the right-angled side refers to the side on the light-emitting surface of the first prism perpendicular to the short side of the digital micromirror device; H4 is the distance from the RTIR to the last lens element of the lens.

[0044] Among them, the rear working distance L of the lens BF The following formula can be satisfied: L BF =H1+H2+H3+H4.

[0045] Furthermore, the reduction in the size of the first prism 221 reduces the overall length of the illumination system along the optical axis f2, thus shrinking the overall size of the illumination system. Additionally, the reduced rear working distance allows for a reduction in the size of the incident lens 24, consequently reducing the lens size and consequently the overall size of the projection device. The rear working distance of the lens and the size of the final lens element (i.e., the incident lens 24) satisfy the following formula: D 1ens =2 L BF tanθ2+ D circle .

[0046] Among them, D 1ens θ2 is the size of the lens in the lens that receives the light beam provided by the illumination system, and D is the numerical aperture angle of the projection lens system. circle The image circle refers to the size of the circular, bright, and clear image that appears on the focal plane after incident light passes through a projection lens; it is also called the image plane size. The image circle of a projection lens is determined by the lens's optical structure; once the design is complete, its corresponding image circle is fixed.

[0047] Optionally, such as Figure 3 As shown, the prism assembly 22 also includes a second prism 222 and a flat glass 223. The second prism 222 is surrounded by a second light-incident surface B4, a second light-exiting surface B5, and a curved surface B6. The second light-exiting surface B5 is opposite to one side of the flat glass 223, and the bottom surface B3 of the first prism 221 is opposite to the other side of the flat glass. The second light-incident surface B4 is used to receive the light beam S2 and guide the light beam S2 to the curved surface B6. The curved surface B6 is used to reflect the light beam S2 toward the second light-exiting surface B5.

[0048] The prism assembly can be used to separate the illumination beam and the imaging beam in the optical path. The second prism can make the incident direction of the illumination beam and the optical axis of the lens in the same direction, which helps to reduce the thickness of the illumination system.

[0049] The second prism 222 can be used to adjust the direction of the illumination beam and reduce the thickness of the illumination system. At the same time, the curved surface B6 of the second prism 222 can reduce the spot size of the illumination beam, thereby further reducing the size of the galvanometer assembly.

[0050] The flat glass 223 can be used to increase the distance between the second prism 222 and the first prism 221, so as to avoid structural interference between the structure of the second prism 222 and the galvanometer assembly 25 and the digital micromirror device 21.

[0051] Optionally, such as Figure 8 As shown, Figure 8This is a schematic diagram of another illumination system provided in this application, viewed from a plane perpendicular to the digital micromirror device. The illumination system also includes a light homogenizing component 26 and a beam collimating magnifying lens group 27. The light homogenizing component 26 is used to process the received light and guide it to the beam collimating magnifying lens group 27. The beam collimating magnifying lens group 27 is used to guide the beam to the prism component.

[0052] Beam homogenization components, such as light guides or compound eye lenses, can be used to shape and homogenize the laser beam incident from a light source. Beam homogenization refers to transforming a non-uniform intensity distribution beam into a beam with a uniform cross-sectional distribution through beam transformation. A laser beam spot refers to the random, granular intensity pattern formed by the interference of these beams when a laser source illuminates a rough surface such as a screen or any other object that produces diffuse reflection or diffuse transmission.

[0053] A light guide is a tubular device composed of four planar reflective sheets, also known as a hollow light guide. Light is reflected multiple times inside the light guide to achieve a uniform light effect. Solid light guides can also be used. The inlet and outlet of the light guide are rectangular with the same shape and area. The light beam enters from the inlet and exits from the outlet, undergoing beam homogenization and laser spot optimization during its journey through the light guide. A compound eye lens is typically formed by a series of small lenses. Two parallel arrays of compound eye lenses are arranged to segment the input laser beam. Subsequent focusing lenses then accumulate the segmented beams, achieving beam homogenization and spot optimization.

[0054] Optionally, such as Figure 8 As shown, the beam collimating magnifying lens group 27 includes a first lens 271, a second lens 272, and a third lens 273 arranged sequentially along the optical path direction f1. The first lens 271 can be a spherical lens or an aspherical lens; the second lens 272 can be a spherical lens or an aspherical lens; and the third lens 273 can be a spherical lens or an aspherical lens. The specific lens specifications are not limited in this embodiment.

[0055] Among them, the principal optical axis C2 of the first lens 271 is rotated by a first included angle θ1 in the counterclockwise direction from a state parallel to the principal optical axis C1 of the light homogenizing component 26.

[0056] The first lens 271 is tilted relative to the principal optical axis C1 and can be used to compensate for the optical path; the optical axes of the second lens 272 and the third lens 273 are parallel to the principal optical axis C1 and can be used to converge the light beam and collimate the light rays.

[0057] Optionally, such as Figure 3As shown, the beam collimating magnifying lens group 27 may also include a plane mirror 274. The plane mirror 274 is used to receive the beam emitted from the third lens 273 and guide the beam to the prism assembly 22. The plane where the plane mirror 274 is located can be at an angle of 45 degrees to the principal optical axis C1. In this way, the plane mirror can cause the direction of the light emitted from the third lens 273 to be folded by 90 degrees, thereby shortening the length of the lighting system along the principal optical axis C1 and reducing the size of the lighting system.

[0058] In summary, this application provides an illumination system including a digital micromirror device, a prism assembly, a light-blocking plate, and a projection lens. The light-blocking plate includes an opening area and a blocking area. The digital micromirror device processes the received light beam and reflects it, guiding the imaging beam output by the digital micromirror device when its mirror is in the open state to the prism assembly. The imaging beam can be projected onto the projection lens through the prism assembly and the opening area of ​​the light-blocking plate. The blocking area of ​​the light-blocking plate can block the non-imaging beam output by the digital micromirror device when its mirror is in the closed state from being projected onto the projection lens. In other words, the light-blocking plate can reduce the non-imaging beam projected onto the projection lens, thereby improving the contrast of the projected display image while achieving miniaturization. This solves the problem of poor image quality in related technologies and achieves the effect of improving the quality of the projected display image.

[0059] In addition, smaller prism components can reduce the size of the lighting system.

[0060] like Figure 9 As shown, Figure 9 This is a schematic diagram of a projection device provided in an embodiment of this application. The projection device includes an illumination system 31, a light source assembly 33, and a diffusion assembly 34, etc.

[0061] The lighting system 31 can refer to the lighting system in any of the above embodiments. The prism assembly in the lighting system 31 is smaller in size, and thus the lighting system 31 is smaller in size. The optical height of the lighting system can be as low as 32 mm to 45 mm, which can make the projection device smaller in size. In addition, the projection system 31 has a digital micromirror device, a light-blocking plate and a projection lens 311. The light-blocking plate can reduce the non-imaging beams emitted by the projection lens 311, thereby reducing the impact of the non-imaging beams emitted by the digital micromirror device on the contrast of the projected display image, and improving the quality of the projected display image of the projection device.

[0062] The diffusion component 34 may include a diffusion wheel or a diffusion sheet, which can be used to scatter the light beam incident from the light source and guide the scatter-spotted light beam to the homogenizing component.

[0063] The light source assembly 33 may include a blue laser emitter 331, a green laser emitter 332, a red laser emitter 333, and an optical path assembly 334. The optical path assembly 334 may include a first dichroic filter 3341, a second dichroic filter 3342, and a lens assembly 3343. A dichroic filter is a filter that can almost completely transmit light of a certain wavelength while almost completely reflecting light of other wavelengths.

[0064] The first dichroic filter 3341 can be used to transmit blue laser light and reflect green laser light. The second dichroic filter 3342 can be used to transmit red laser light and reflect blue and green laser light. The lens assembly 3343 can be used to converge the laser beam and guide the converged laser beam to the diffusion assembly 34.

[0065] In summary, this application provides a projection device including an illumination system, a light source assembly, and a diffusion assembly. The illumination system includes a digital micromirror device (DMM), a prism assembly, a light-blocking plate, and a projection lens. The light-blocking plate includes an opening area and a blocking area. The DMM processes the received light beam and reflects it, guiding the imaging beam output when the DMM's mirror is in the open state to the prism assembly. The imaging beam can pass through the prism assembly and the opening area of ​​the light-blocking plate towards the projection lens. The blocking area of ​​the light-blocking plate can prevent non-imaging beams output when the DMM's mirror is in the closed state from reaching the projection lens, thus reducing the amount of non-imaging beams reaching the projection lens. This improves the contrast of the projected display while maintaining a miniaturized size, solving the problem of poor image quality in related technologies and achieving an improved image quality.

[0066] In addition, smaller prism components can reduce the size of the lighting system, which in turn makes the projection device smaller.

[0067] In this application, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0068] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A lighting system, characterized in that, The lighting system includes a digital micromirror device, a prism assembly, a light-blocking plate, and a projection lens arranged sequentially along the optical path of the lighting system. The prism assembly includes a first light-incident surface and a first light-outcident surface. The digital micromirror device is located outside the first light-incident surface, and the light-blocking plate is located outside the first light-outcident surface. The digital micromirror device is used to process the received light beam and guide it to the first light-incident surface of the prism assembly. The light-blocking plate includes an opening area and a blocking area. The size of the opening area is greater than or equal to the maximum size of the light spot on the plane of the light-blocking plate when the reflector in the digital micromirror device is in the open state. This allows the imaging light beam to pass through the opening area and be directed toward the projection lens. The blocking area of ​​the light-blocking plate is used to block the non-imaging light beam output by the reflector in the digital micromirror device when it is in the closed state from being directed toward the projection lens. The prism assembly includes a first prism, which is formed by a first light-incident surface, a first light-outcrystal surface, and a bottom surface, wherein the first light-incident surface and the first light-outcrystal surface are perpendicular to each other. The non-imaging beam includes a first beam that is directed toward the first light-incident surface of the prism assembly and emitted through the bottom surface of the first prism, and a second beam that is directed from the digital micromirror toward the light-incident port. The blocking area of ​​the light-blocking plate includes a first blocking area for blocking the first beam and a second blocking area for blocking the second beam. The first prism is used to receive the imaging beam through the first light-incident surface and guide the imaging beam to the bottom surface. The bottom surface reflects the imaging beam to the first light-out surface to output the first prism. The size of the first light-incident surface is greater than or equal to the size of the light spot on the plane where the imaging beam illuminates the first light-incident surface. The digital micromirror device is rectangular, and its short side is parallel to the first incident light surface and perpendicular to the first emitting light surface; the first incident light surface satisfies the formula: P≥2 L tanθ+W DMD ; Where P is the side length of the first incident surface, L is the distance from the mirror of the digital micromirror device to the first prism; θ is the numerical aperture angle of the illumination system, and W... DMD The width of the short side of the digital micromirror device; The numerical aperture angle of the lighting system satisfies the formula: θ=arcsin(1 / 2) F); where F is the F-number of the lighting system.

2. The lighting system according to claim 1, characterized in that, The prism assembly further includes a second prism and a flat glass plate. The second prism is formed by a second light-incident surface, a second light-exit surface, and a curved surface. The second light-exit surface is opposite to one side of the flat glass plate, and the bottom surface of the first prism is opposite to the other side of the flat glass plate. The second light-incident surface is used to receive the light beam and guide the light beam to the curved surface, and the curved surface is used to reflect the light beam toward the second light-exit surface.

3. The lighting system according to any one of claims 1-2, characterized in that, The lighting system also includes a galvanometer assembly located between the digital micromirror device and the prism assembly.

4. The lighting system according to any one of claims 1-2, characterized in that, The illumination system further includes a light homogenizing component and a beam collimating magnifying lens group. The light homogenizing component is used to process the received light beam and guide it to the beam collimating magnifying lens group, and the beam collimating magnifying lens group is used to guide the light beam to the prism component.

5. The lighting system according to claim 4, characterized in that, The beam collimating magnifying lens group includes a first lens, a second lens, and a third lens arranged sequentially along the optical path direction. The principal optical axis of the first lens is rotated counterclockwise from a state parallel to the principal optical axis of the light homogenizing component by a first included angle.

6. A projection device, characterized in that, Includes the lighting system described in any one of claims 1-5.

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