Prism structure, optical system, optical display apparatus, and terminal device

Abstract

A prism structure (620), an optical system (320), an optical display apparatus (300), and a terminal device, for use in increasing the contrast of imaging of a projection lens (340, 640). The optical system (320) comprises a prism structure (620); the prism structure (620) comprises a first layer (Q1), a second layer (Q2) and a third layer (Q3) which are sequentially stacked, and a fourth side (L24) of the second layer (Q2) is painted black; the first layer (Q1) is used for directing an illumination beam into the second layer (Q2), or directing a non-projection beam out; the second layer (Q2) is used for directing the illumination beam into a display chip (630), and for reflecting a projection beam reflected from the display chip (630) to the third layer (Q3), and directing the non-projection beam reflected from the display chip (630) to a third side or directing the non-projection beam out to the first layer (Q1); and the third layer (Q3) is used for directing the projection beam into a projection lens (340, 640). By directing the non-projection beam to the black-painted prism surface for absorption or to be directed out of the prism structure (340), the non-projection beam in the optical system (320) can be effectively suppressed, the probability of the non-projection beam entering the projection lens (340, 640) and participating in imaging can be reduced, and the contrast of projection can be increased.

Description

Prism structure, optical system, optical display device and terminal equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on August 4, 2023, with application number 202310984749.3 and application name "A prism structure, optical system, optical display device and terminal equipment", all contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of optical technology, and in particular to a prism structure, an optical system, an optical display device, and a terminal device. Background Art

[0004] In recent years, with the development of projection display technology, people's demand for projection display effects has also increased. Among various projection display technologies, digital light processing (DLP) technology has become increasingly popular in the market due to its advantages of high brightness and high contrast, and has gradually become the mainstream technical solution in the projection display field.

[0005] To achieve a compact structure, DLP displays typically use total internal reflection (TIR) ​​prisms or reverse total internal reflection (RTIR) prisms to couple illumination light. However, in existing prism solutions, non-projected light beams generated by the DLP display also enter the projection lens and participate in projection. After one or more reflections or refractions in the projection lens, these non-projected light beams form stray light on the final image plane, affecting the contrast of the final image.

[0006] In summary, how to improve the contrast of projection lens imaging is a technical problem that urgently needs to be solved.

[0007] Summary of the Invention

[0008] The present application provides a prism structure, an optical system, an optical display device, and a terminal device for improving the contrast of projection lens imaging.

[0009] In a first aspect, the present application provides a prism structure, comprising a first triangular prism, a quadrangular prism, and a second triangular prism, wherein the first triangular prism comprises three quadrilateral side faces and two triangular main faces, the quadrangular prism comprises four quadrangular side faces and two quadrangular main faces, the second triangular prism comprises three quadrangular side faces and two triangular main faces, the second side face of the first triangular prism is affixed to the first side face of the quadrangular prism, the second side face of the quadrangular prism is affixed to the first side face of the second triangular prism, and the fourth side face of the quadrangular prism is painted black. The first side face of the quadrangular prism and the second side face of the quadrangular prism are two opposite faces, and the fourth side face of the quadrangular prism is a face connecting the first side face of the quadrangular prism and the second side face of the quadrangular prism and opposite to the third side face of the second triangular prism.

[0010] In the above solution, the fourth side of the prism is painted black. This effectively suppresses the non-projection light within the prism structure by directing it to absorb the non-projection light beam, allowing a relatively pure projection light beam to enter the projection lens for imaging, thereby improving the projection lens's projection contrast. Furthermore, this prism structure achieves non-projection light suppression simply by painting the prism surface black. This eliminates the need for an additional display chip, angle-selective coatings, or elaborate design of the prism structure's angle and position constraints to deflect the non-projection light beam. This reduces the size, cost, and weight of the prism structure.

[0011] In a second aspect, the present application provides an optical system comprising a prism structure, wherein a display chip is positioned in a first direction of the prism structure, and a projection lens is positioned in a second direction of the prism structure. The prism structure comprises a first layer, a second layer, and a third layer stacked in sequence along the second direction, with the fourth side of the second layer opposite the first direction being painted black. When the optical system is in operation, the first layer is used to direct an illumination beam into the second layer or to direct a non-projection beam out; the second layer is used to direct the illumination beam into the display chip, and to reflect a projection beam reflected from the display chip to the third layer, and to guide the non-projection beam reflected from the display chip to the fourth side or to direct it to the first layer; and the third layer is used to direct the projection beam into the projection lens.

[0012] In the above scheme, the optical system can guide the non-projection light beam to the blackened prism surface for absorption or export the prism structure, thereby effectively suppressing the non-projection light beam in the optical system, reducing the probability of it entering the projection lens to participate in imaging, and improving the projection contrast.

[0013] In one possible design, the third layer also reflects non-projection light beams from the display chip toward the fourth side surface. This way, even if not all of the non-projection light beams from the display chip are reflected back to the second layer, but a portion is reflected to the third layer, they can be reflected by the third layer onto the blackened prism surfaces in the second layer and absorbed, preventing them from entering the subsequent projection lens. In this way, the third layer can be considered a leak-proof layer for the second layer, suppressing any non-projection light beams that fail to reach the second layer, further eliminating non-projection light beams from the optical system and reducing the impact of stray light.

[0014] In one possible design, the projected beam includes the beam reflected by the display chip at a first deflection angle, and the non-projected beam includes the beam reflected by the display chip at a second deflection angle and the beam reflected by the display chip at a third deflection angle, wherein different deflection angles correspond to different states of the display chip. Optionally, the first deflection angle may be the deflection angle corresponding to the "on" state, the second deflection angle may be the deflection angle corresponding to the "flat" state, and the third deflection angle may be the deflection angle corresponding to the "off" state. In other words, the projected beam may include the "on" state beam, and the non-projected beam may include the "off" state beam and the "flat" state beam. In this way, by suppressing both the "off" state beam and the "flat" state beam, which are both invalid beams, it is possible to minimize the large amount of "off" state beam and "flat" state beam entering the projection lens to form stray light, thereby helping to improve the contrast of the projected image.

[0015] It should be noted that the prism structure in the second aspect may be the prism structure in the first aspect, or may be another prism structure. For example, it may be composed of at least four prisms, and any of the at least four prisms may be a triangular prism, a quadrangular prism, or a pentaprism. It should be understood that any prism structure capable of absorbing non-projection light beams by coating the prism surface black is within the scope of protection of this application.

[0016] For ease of introduction, the prism structure in the second aspect is taken as an example of the prism structure in the first aspect mentioned above. In this case, the first layer is the first triangular prism, the second layer is the quadrangular prism, and the third layer is the second triangular prism. The display chip is placed on the outside of the third side of the quadrangular prism, and the projection lens is placed on the outside of the second side of the second triangular prism.

[0017] In one possible design of the first or second aspect, the angle between the first side surface of the prism and the third side surface of the prism is 45°. This 45° angle can mirror a display chip located in a first direction of the prism structure to a direction opposite to a second direction of the prism structure. As a result, the mirrored display chip and the projection lens located in the second direction of the prism structure can be coaxial. The projection light beam reflected by the display chip is transmitted to the projection lens in a straight line, thereby reducing the probability of deformation or misalignment of the projection light beam and improving the imaging quality of the projection lens.

[0018] In a further possible design, the second side surface of the second triangular prism is perpendicular to the third side surface of the second triangular prism. Thus, the projection beam reflected by the quadrangular prism enters the second triangular prism in a straight line and then exits from the second side surface of the second triangular prism. This exit direction can remain parallel to the third side surface of the quadrangular prism at the aforementioned 45° angle. Furthermore, because the second side surface of the second triangular prism is perpendicular to its third side surface, the projection beam exiting from the second side surface of the second triangular prism enters the third side surface perpendicularly and then exits the third side surface perpendicularly, thereby ensuring that the direction of the projection beam does not change.

[0019] In one possible design of the first or second aspect, the third side surface of the quadrangular prism and the third side surface of the second triangular prism are located in the same plane, and the display chip can be located below this plane. In this way, the third side surface of the quadrangular prism and the third side surface of the second triangular prism form the bottom surface of the prism structure. This flat surface not only improves the appearance but also allows the light beam reflected by the display chip to refract into the quadrangular prism and the second triangular prism at the same vertical position, facilitating the design of the light transmission path.

[0020] In a further possible design, the fourth side of the prism is parallel to the third side, and the area of ​​the fourth side is smaller than the area of ​​the third side. In this way, the third side of the prism serves as the bottom surface of the prism structure, and the fourth side of the prism serves as the top surface of the prism structure. The larger bottom surface area helps to make the prism structure more stable when placed.

[0021] In one possible design of the second aspect, a portion of the non-projection light beam reflected by the display chip undergoes one or more reflections in the prism, with some being directed to the fourth side surface of the prism and some being reflected by the first triangular prism before being directed out of the prism structure. In this manner, the non-projection light beam reflected by the prism can be directed to the blackened surface for absorption, or directed out of the prism structure.

[0022] In one possible design of the second aspect, another portion of the non-projection light beam reflected by the display chip is refracted through the third side surface of the prism to the fourth side surface of the prism. In this way, the non-projection light beam reflected into the prism can also be directly transmitted to the blackened surface of the prism for absorption.

[0023] In one possible design of the second aspect, another portion of the non-projection light beam reflected by the display chip is reflected by the second side surface of the second prism to the fourth side surface of the quadrangular prism. Thus, the non-projection light beam reflected by the second prism can be directed to the blackened surface of the quadrangular prism for absorption.

[0024] In one possible design of the second aspect described above, the projection light beam reflected by the display chip is reflected from the first side surface of the prism to the second side surface of the prism, then transmitted through the second side surface of the prism to the second side surface of the second prism, and then directed to the projection lens through the second side surface of the second prism. In this manner, the projection light beam reflected from the prism can be directly reflected by the prism into the second prism, and then directly refracted by the second prism into the projection lens. This transmission method can guide the projection light beam to the projection lens via a shorter optical path, thereby reducing energy waste in the projection light beam.

[0025] In one possible design of the second aspect, the non-projection light beam reflected by the display chip is reflected from the first side surface of the prism to the second side surface of the prism, and then reflected from the second side surface of the prism to the fourth side surface of the prism. In this manner, the non-projection light beam reflected into the prism can be guided to the blackened surface for absorption after two reflections in the prism. This shortens the transmission path of the non-projection light beam from entering the prism to its elimination, thereby reducing the probability of stray light introduced by multiple reflections or refractions of the non-projection light beam in the prism.

[0026] In a possible design of the second aspect above, the incident angle of the projection light beam on the second side surface of the prism is smaller than the incident angle of the non-projection light beam on the second side surface of the prism. The smaller the incident angle of the projection light beam on the second side surface of the prism, the more likely it is to be smaller than the critical angle of total reflection corresponding to the second side surface of the prism, and the easier it is to achieve refraction of the projection light beam on the second side surface of the prism. The larger the incident angle of the non-projection light beam on the second side surface of the prism, the more likely it is to be larger than the critical angle of total reflection corresponding to the second side surface of the prism, and the easier it is to achieve total reflection of the non-projection light beam on the second side surface of the prism. In other words, by making the incident angle of the projection light beam on the second side surface of the prism smaller than the incident angle of the non-projection light beam on the second side surface of the prism, it is helpful to utilize the critical angle of total reflection of the second side surface of the prism to separate the projection light beam and the non-projection light beam.

[0027] In one possible design of the second aspect, the tilt angle of the second side surface of the prism and the refractive index of the material of the prism are selected to achieve refraction of the projection beam on the second side surface of the prism and reflection of the non-projection beam on the second side surface of the prism. In this way, the tilt angle of the second side surface of the prism and the refractive index of the material of the prism can be selected to meet the requirements for ensuring transmission of the projection beam and reflection of the non-projection beam, thereby achieving the function of suppressing the non-projection beam and transmitting the projection beam.

[0028] In one possible design of the second aspect, the angle of incidence of the projection light beam with the maximum incident angle in the projection beam on the second side surface of the prism is less than the critical angle of total internal reflection corresponding to the second side surface of the prism, and the angle of incidence of the projection light beam with the minimum incident angle in the non-projection beam on the second side surface of the prism is greater than or equal to the critical angle of total internal reflection corresponding to the second side surface of the prism. In this way, there is no overlap between the angle of incidence of the projection beam on the second side surface of the prism and the angle of incidence of the non-projection beam on the second side surface of the prism, thereby maintaining a certain distance between the projection beam and the non-projection beam, thereby supporting the separation of the two beam states through reflection or refraction in the prism structure.

[0029] In one possible design of the second aspect, the refractive index of the quadrangular prism is the same as the refractive index of the second triangular prism. Thus, the second side surface of the bonded quadrangular prism and the first side surface of the second triangular prism act like transparent glass for the transmission of the projection light beam, thereby maintaining the main transmission direction of the projection light beam unchanged.

[0030] In one possible design of the second aspect, one or more outer surfaces of the prism structure, excluding the fourth side surface of the quadrangular prism, are coated black as portions not in the effective light path. By coating all surfaces of the prism structure where no effective light beams pass, these blackened surfaces can directly absorb non-projected light beams projected onto these surfaces, minimizing reflection or refraction of the non-projected light beams within the prism structure and reducing the probability of stray light generated within the projection lens.

[0031] In one possible design of the second aspect, the second prism is fixed to or integrated with the lens element of the projection lens closest to the second prism. This not only reduces the volume of the optical system but also shortens the back focus distance of the optical system, thereby reducing the design difficulty of the back focus system.

[0032] In a further possible design, when the second prism is fixed to the lens, the side of the lens relative to the second prism is configured as a flat surface. In this way, the flat surface of the last lens can be directly attached to the second prism P3 for fixation, and the flat surface makes it easier to fix.

[0033] In a third aspect, the present application provides an optical display device, comprising a display chip, a projection lens, and an optical system designed in any one of the second aspects above, wherein the display chip is used to reflect the illumination light beam introduced from the second layer at different deflection angles, and the projection lens is used to project an enlarged image based on the projection light beam introduced from the third layer.

[0034] In one possible design, the display chip may include, but is not limited to, a digital micromirror device (DMD), a liquid crystal display (LCD) chip, a liquid crystal on silicon (LCOS) chip, or a laser beam scanning (LBS) display.

[0035] In one possible design, the projection lens may include one or more lenses. When the requirements for projection clarity and projection field of view are high, more lenses may be configured in the projection lens. When the requirements for projection clarity and projection field of view are low, fewer lenses may be configured in the projection lens.

[0036] In a possible design, the optical display device further includes a light source, which is configured to emit an illumination light beam to the third layer.

[0037] In a further possible design, the light source may include but is not limited to: a laser diode (LD), a light emitting diode (LED), or an organic light emitting diode (OLED).

[0038] In a possible design, the optical display device further includes a display screen, which is used to display the magnified image from the projection lens.

[0039] In a fourth aspect, the present application provides a terminal device comprising the optical display device described in any one of the designs in the third aspect above.

[0040] In one possible design, the terminal device may be a projector, a head-up display (HUD), or a near-eye display (NED) device.

[0041] The beneficial effects of any one of the designs in the third to fourth aspects mentioned above can refer to the beneficial effects that can be achieved by the corresponding design in the second aspect mentioned above, and this application will not repeat them one by one. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 exemplarily shows a schematic diagram of a total reflection light path provided by the present application;

[0043] FIG2a exemplarily shows a schematic diagram of an application scenario of a projector applicable to the present application;

[0044] FIG2b exemplarily shows a schematic diagram of an application scenario of a vehicle-mounted projector provided by the present application;

[0045] FIG2c exemplarily shows a schematic diagram of an application scenario of a head-up display device provided by the present application;

[0046] FIG2d exemplarily shows a schematic diagram of an application scenario of an augmented reality device provided by the present application;

[0047] FIG3a exemplarily shows a schematic structural diagram of an optical display device provided by the present application;

[0048] FIG3 b exemplarily shows a schematic diagram of stray light distribution in an optical display device;

[0049] FIG3c exemplarily shows a schematic diagram of a prism structure solution provided by the industry;

[0050] FIG3 d exemplarily shows a schematic diagram of another prism structure solution provided by the industry;

[0051] FIG3e exemplarily shows a schematic diagram of another prism structure solution provided by the industry;

[0052] FIG4 exemplarily shows a schematic structural diagram of a prism structure provided by the present application;

[0053] FIG5 is a schematic diagram showing a volume comparison between the prism structure provided by the present application and the prism structure provided by the industry;

[0054] FIG6 exemplarily shows a light path diagram of an optical system provided by the present application;

[0055] FIG7 a exemplarily shows a schematic diagram of a blackening method of a prism structure provided by the present application;

[0056] FIG7 b exemplarily shows a schematic diagram of another blackening method of a prism structure provided by the present application;

[0057] FIG8 a exemplarily shows a schematic diagram of a deflection state of a display chip provided by the present application;

[0058] FIG8 b exemplarily shows a schematic diagram of reflected light of a display chip provided by the present application;

[0059] FIG9 exemplarily shows a schematic diagram of a light beam transmission path provided by the present application;

[0060] FIG10 exemplarily shows a schematic diagram of the same light irradiating a second side surface at different inclination angles provided by the present application;

[0061] FIG11 exemplarily shows a schematic structural diagram of a projection lens provided by the present application;

[0062] FIG12 exemplarily shows a schematic diagram of a fixing method of a lens and a prism structure provided by the present application;

[0063] FIG13 exemplarily shows a schematic diagram of a method for calculating back focus distance provided by the present application;

[0064] FIG14 exemplarily shows a circuit diagram of an optical display device provided by the present application;

[0065] FIG15 exemplarily shows a functional framework diagram of a vehicle provided by the present application. DETAILED DESCRIPTION

[0066] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0067] The following is an explanation of some of the terms used in this application. It should be noted that these explanations are for the purpose of facilitating understanding by those skilled in the art and do not limit the scope of protection claimed in this application.

[0068] 1. Projection beam and non-projection beam

[0069] The projection beam can be understood as the beam that needs to enter the projection lens for projection. Of the light beams reflected by the display chip, a portion is required for projection and can be directed into the projection lens for projection imaging. This portion is the projection beam. In contrast to the projection beam, the non-projection beam can be understood as the beam that does not need to enter the projection lens for projection. Once the non-projection beam enters the projection lens, it is likely to become stray light, affecting the contrast of the projection beam's image. Therefore, it is important to prevent it from entering the projection lens.

[0070] 2. Total Internal Reflection

[0071] Total internal reflection, also known as total internal reflection, is an optical phenomenon. When light travels from a denser medium to a less dense medium, if the angle of incidence is greater than the critical angle of total reflection, the refracted light will all disappear, and all incident light will be reflected without entering the less dense medium. This phenomenon is called total internal reflection. For example, refer to Figure 1. At the interface between a denser medium and a less dense medium, light from the denser medium with an incident angle less than the critical angle of total reflection θ1 (as shown by the dotted line in the figure) can be refracted into the less dense medium, while light from the denser medium with an incident angle greater than or equal to the critical angle of total reflection θ1 (as shown by the solid line in the figure) will all be reflected back into the denser medium. The critical angle of total reflection θ1 is related to the refractive index n1 of the denser medium and the refractive index n2 of the less dense medium, and can be calculated using the following formula (1.1):

[0072] 3. Back focus distance

[0073] The back focal distance (BFD), also known as the back focal length (BFL), can be understood as the distance from the center point of the last lens in the projection lens to the plane where the display chip is located. The last lens in the projection lens can be understood as the lens closest to the prism.

[0074] The previous text introduced some of the terms involved in this application. The following text introduces the possible application scenarios of this application.

[0075] In one possible application scenario, the prism structure in the present application can be integrated into a projector, please refer to Figure 2a, and the projector can project light onto a wall or a projection screen, so that the wall or the projection screen displays an image corresponding to the light. Depending on the projection ratio, projectors can be divided into long-focus projectors, short-focus projectors, and ultra-short-focus projectors. Long-focus projectors are suitable for use in bedrooms and living rooms, and are generally placed on bedside tables or next to sofas. Short-focus projectors are mainly suitable for educational or business projection, such as cinema projection, office projection, etc. Ultra-short-focus projectors can be set at a short distance, such as a laser TV projector, which basically only needs to be placed on a TV cabinet.

[0076] In some specialized scenarios, projectors can also be installed on vehicles. For example, those installed on vehicles are called onboard projectors, those installed on aircraft are called onboard projectors, and those installed on ships are called onboard projectors. Taking vehicle installation as an example, as shown in Figure 2b, onboard projectors can be installed anywhere in the vehicle cabin, such as above the seat headrest, behind the seat, in the armrest, or in front of the rear window. In some scenarios, onboard projectors can also be steerable, allowing them to project onto the cabin curtains, skylights, side windows, or front and rear windshields.

[0077] In another possible application scenario, the prism structure in the present application can be integrated into a head-up display (HUD), please refer to Figure 2c. Figure 2c takes the HUD installed on a vehicle as an example. The HUD can project the formed image (called the HUD virtual image) into the driver's (also called the eye box) front field of view and integrate it with the real road information to enhance the driver's perception of the actual driving environment. For example, the HUD can superimpose the HUD virtual image carrying navigation information and / or instrument information (such as driving speed, mileage, speed, temperature, fuel level, headlight status, etc.) on the real environment outside the car, so that the driver can obtain an augmented reality visual effect. It can be specifically applied to scenarios such as augmented reality (AR) navigation, adaptive cruise control, lane departure warning, etc. Among them, HUD includes but is not limited to windshield (W)-HUD, augmented reality head up display (AR-HUD), etc.

[0078] In another possible application scenario, the prism structure of the present application can be integrated into a near-eye display (NED) device, which can be, for example, an augmented reality (AR) device, a virtual reality (VR) device, or a mixed reality (MR) device. AR devices may include, but are not limited to, AR glasses or AR helmets, VR devices may include, but are not limited to, VR glasses or VR helmets, and MR devices may include, but are not limited to, MR glasses or MR helmets. Referring to FIG. 2d , taking AR glasses as an example, a user can wear AR glasses to play games, watch videos, participate in virtual meetings, or perform video shopping.

[0079] It should be understood that the possible application scenarios given above are only examples, and the prism structure provided in this application can also be applied to other possible scenarios, not limited to the scenarios shown in the examples above. For example, it can also be applied to car displays, and for example, it can also be applied to smart car lights.

[0080] In the present application, the prism structure can be integrated into an optical display device, which can be, for example, the aforementioned projector, HUD, or NED device. Referring to FIG3a , a schematic structural diagram of an optical display device is shown. The optical display device 300 may include a light source 310, an optical system 320, a display chip 330, and a projection lens 340. The prism structure can be integrated into the optical system 320. Optionally, the optical display device 300 may further include a display screen 350. The light source 310 is located to the left of the optical system 320 in the diagram, the display chip 330 is located below the optical system 320 in the diagram, the projection lens 340 is located to the right of the optical system 320 in the diagram, and the display screen 350 is located to the right of the projection lens 340 in the diagram. When the optical display device 300 is working, the light source 310 can emit illumination light, which is refracted by the prism structure in the optical system 320 and illuminates the display chip 330. It is then reflected back to the optical system 320 by the display chip 330 and exported to the projection lens 340 through the prism structure in the optical system 320. The image corresponding to the incident light is then magnified by the projection lens 340 and finally imaged on the display screen 350.

[0081] As will be appreciated, the light beams reflected by the display chip 330 typically include projection beams and non-projection beams. The projection beam is the beam required for projection, while the non-projection beam is the beam not required for projection and should be prevented from entering the projection lens 340. However, as described in the background art, existing prism solutions also direct the non-projection beams toward the projection lens 340. After one or more reflections or refractions within the projection lens 340, these non-projection beams are likely to generate stray light that travels in all directions, as shown in Figure 3b. This stray light will obviously interfere with the brightness of the projection beam imaged by the projection lens 340, thereby reducing projection contrast.

[0082] Although the industry has proposed some solutions to prevent non-projection light beams from entering the projection lens, most of these solutions require sacrificing volume or cost, such as:

[0083] In one solution, as shown in Figure 3c, two display chips 1 and 2 are provided so that the brightness of each pixel on display chip 1, after passing through display chip 2, can achieve a squared relationship based on the original contrast. For example, if a bright pixel and a dark pixel achieve a 10:1 contrast ratio after processing on display chip 1, then after processing on the second display chip 2, a further 10:1 ratio can be added to the 10:1 contrast ratio, reducing the total contrast ratio to 100:1. While this solution effectively increases the brightness difference between different pixels, adding display chips also requires a corresponding increase in the projection light path, thus complicating the overall structure of the projection display device and increasing its size. Furthermore, display chips are expensive, and adding another display chip would significantly increase costs, which does not meet the design principles of miniaturization and low cost.

[0084] Another solution, as shown in Figure 3d, takes advantage of the different exit angles of the projection beam and non-projection beam reflected by the display chip. By coating the surface of prism 4 opposite prism 3 with an angle-selective film, and configuring the angle-selective film to have a selection angle greater than or equal to the angle of incidence of the projection beam on that surface and less than the angle of incidence of the non-projection beam on that surface, projection beams with angles less than or equal to the selected angle can pass through the angle-selective film and enter the projection lens, while non-projection beams with angles greater than the selected angle cannot pass through the angle-selective film and are reflected back to prism 3. While this approach can utilize the angle-selective properties of the angle-selective film to filter the non-projection beam, the current coating effect of the angle-selective film is difficult to achieve ideal, and there is a high probability that some non-projection beams will still pass through the angle-selective film and enter the projection lens, affecting projection contrast. Furthermore, after being reflected back to prism 3, the non-projection beam may undergo one or more reflections or refractions through prism 3, prism 2, and prism 1 before re-entering the surface of prism 4 opposite prism 3. If the angle of incidence at this point is less than or equal to the selected angle, the non-projection beam will pass through the angle-selective film and enter the subsequent projection lens, becoming stray light. This solution can only partially prevent a portion of the non-projection beam from entering the projection lens. Furthermore, adding the angle-selective film also increases costs, failing to meet the low-cost design concept.

[0085] In another solution, see Figure 3e, prisms 1, 2, and 3 are spliced ​​together, and through precise design, special spatial position and angular constraints are formed between the three prisms. Through this special spatial position and angular constraint, the non-projection light beam (as shown by the dark solid line in the figure) is guided out from one or more prisms among prisms 1, prism 2, and prism 3, and the projection light beam (as shown by the light solid line in the figure) is totally reflected on surface S1 of prism 2 to prism 3, and then guided out from prism 3 to the projection lens. Although this solution can guide the non-projection light beam out of the prism structure, its implementation is completely dependent on the spatial position and angular design of the three prisms. The three prisms need to meet many beam constraint conditions, resulting in the entire prism structure requiring a larger spatial volume to be implemented, which in turn greatly increases the volume and weight of the entire device.

[0086] In view of this, the present application proposes a prism structure that can separate the projection beam and the non-projection beam without sacrificing the overall volume, weight or cost as much as possible, so as to prevent the non-projection beam from entering the subsequent projection lens and improve the projection contrast of the projection lens.

[0087] Based on the above content, the prism solution proposed in this application is described in detail below in conjunction with Figures 4 to 12.

[0088] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0089] In addition, in this application, "angle" does not refer to an absolute angle, and a certain degree of engineering error is allowed. "Uniform" does not mean absolute uniformity, and a certain degree of engineering error is allowed. "Vertical" does not mean absolute verticality, and a certain degree of engineering error is allowed.

[0090] As shown in Figure 4, a schematic diagram of the structure of a prism structure provided by the present application is shown. Figure 4 (A) shows a three-dimensional view of the prism structure, Figure 4 (B) shows a front view of the prism structure, and Figure 4 (C) shows a left view of the prism structure. Referring to Figures 4 (A) to 4 (C), the prism structure includes a first triangular prism P1, a quadrangular prism P2, and a second triangular prism P3. The first triangular prism P1, the quadrangular prism P2, and the second triangular prism P3 are spliced ​​into a prism. For the sake of convenience, taking the perspective shown in (A) in Figure 4 as an example, the side on the left side of any prism or quadrangular prism in the figure is called the first side, the side on the right side of the figure is called the second side, the side at the bottom of the figure is called the third side, the side in front of the figure is called the first principal surface, the side in the back of the figure is called the second principal surface, and the side above the quadrangular prism in the figure is called the fourth side. Then: the first prism P1 includes three sides that are quadrilaterals and two principal surfaces that are triangular, the quadrangular prism P2 includes four sides that are quadrilaterals and two principal surfaces that are quadrilaterals, the second prism P3 includes three sides that are quadrilaterals and two principal surfaces that are triangular, and the second side of the first prism P1 is in contact with the first side of the quadrangular prism P2, the second side of the quadrangular prism P2 is in contact with the first side of the second prism P3, and the fourth side of the quadrangular prism P2 is painted black.

[0091] Optionally, in the prism structure, any two mating side surfaces may have the same shape and size. For example, referring to FIG4 (A), the second side surface of the first triangular prism P1 and the first side surface of the quadrangular prism P2 have the same shape and size, and the second side surface of the quadrangular prism P2 and the first side surface of the second triangular prism P3 have the same shape and size.

[0092] Further optionally, the joining of the two side surfaces can be achieved by pasting the four corners of the two side surfaces together. For example, the second side surface of the first prism P1 and the first side surface of the quadrangular prism P2 are joined, which can be understood as the four corners of the second side surface of the first prism P1 and the four corners of the first side surface of the quadrangular prism P2 being correspondingly pasted together, and the second side surface of the quadrangular prism P2 and the first side surface of the second prism P3 are joined, which can be understood as the four corners of the second side surface of the quadrangular prism P2 and the four corners of the first side surface of the second prism P3 being correspondingly pasted together. In addition to the four corners pasted together, there is also a thin air layer between the second side surface of the first prism P1 and the first side surface of the quadrangular prism P2, and between the second side surface of the quadrangular prism P2 and the first side surface of the second prism P3.

[0093] It is understood that the fourth side surface of the quadrangular prism P2 is painted black, which means that the outer surface of the quadrangular prism P2 is painted black. This blackening operation can be performed before splicing the first prism P1, the quadrangular prism P2, and the second prism P3 together, or after splicing the first prism P1, the quadrangular prism P2, and the second prism P3 together, without limitation.

[0094] It is understandable that any black material can be selected for blackening, such as ink, water-based paint, paint or ink.

[0095] Using the prism structure shown in Figure 4, by painting the fourth side of the prism P2 black, the non-projection light beam can be directed to this blackened fourth side for absorption, allowing a relatively pure projection light beam to enter the projection lens for imaging. This prism structure eliminates non-projection light simply by painting the prism surface black. This eliminates the need for an additional display chip as shown in Figure 3c, nor does it require an additional angle-selective coating as shown in Figure 3d. This reduces the probability of non-projection light beams entering the projection lens, thereby improving projection contrast, while minimizing the need for bulk, cost, and weight.

[0096] In addition, compared with the prism structure shown in Figure 3e, the prism structure shown in Figure 4 can have a smaller volume. For example, please refer to Figure 5, which exemplifies a schematic diagram of the volume comparison between the prism structure shown in Figure 4 and the prism structure shown in Figure 3e. Among them, Figure 5 (A) shows the prism structure shown in Figure 3e, and Figure 5 (B) shows the prism structure shown in Figure 4. Referring to Figure 5 (A) and Figure 5 (B), it can be seen that the prism structure shown in Figure 4 can be considered to be obtained by cutting off the upper half, about 1 / 4 of the left side, and about 1 / 4 of the right side of the prism structure shown in Figure 3e along the bold black line shown in Figure 5 (A), and painting the top surface of the cut prism structure black. It can be seen that the illustrated bottom side length and height of the prism structure shown in Figure 4 are shorter than those of the prism structure shown in Figure 3e. For example, actual product measurements revealed that the base length of the prism structure shown in Figure 4 is approximately 28% shorter than that of the prism structure shown in Figure 3e, and the volume of the prism structure shown in Figure 4 is approximately 58% less than that of the prism structure shown in Figure 3e. This significantly reduces the volume and weight of the prism structure. Furthermore, due to the reduced base length of the prism structure, the distance from the base of the prism structure to the subsequent projection lens is also shortened. This also helps reduce the back focus length of the optical display device, thereby easing the design difficulty of the back focus system.

[0097] The above content introduces the prism structure. This application also provides an optical system, which is introduced in detail below.

[0098] Please refer to FIG6 , which exemplarily shows a light path diagram of an optical system provided by the present application. The optical system includes a prism structure 620, a display chip 630 is placed in a first direction of the prism structure 620 (as shown in the bottom of the figure), and a projection lens 640 is placed in a second direction of the prism structure 620 (as shown in the right of the figure). Optionally, a light source 610 is placed in a third direction of the prism structure 620 (as shown in the upper left). The prism structure 620 may include a first layer Q1, a second layer Q2, and a third layer Q3 stacked in sequence along the second direction, and the second layer Q2 has a fourth side surface L in the opposite direction of the first direction (as shown in the top of the figure). 24 It is understood that FIG6 takes the first direction as the bottom of the figure, the second direction as the right of the figure, and the third direction as the upper left of the figure as an example, but the first direction, the second direction, or the third direction may also be any other direction or directions, such as any other direction or directions among the top, bottom, left, right, upper left, lower left, upper right, and lower right, without specific limitation.

[0099] Please continue to refer to Figure 6. When the optical system is working, the light source 610 can emit an illumination beam to the first layer Q1 of the prism structure 620. The first layer Q1 can guide the illumination beam incident therein to the second layer Q2. The second layer Q2 can guide the illumination beam from the first layer Q1 to the display chip 630. The display chip 630 can reflect the illumination beam introduced therein at different deflection angles to obtain a projection beam and a non-projection beam, and can reflect the projection beam and all or part of the non-projection beam back to the second layer Q2. Among them, after the projection beam enters the second layer Q2, it can be reflected by the second layer Q2 to the third layer Q3, and then the projection beam is guided by the third layer Q3 to the projection lens 640 for imaging. In contrast, after the non-projection beam enters the second layer Q2, it can be guided to the fourth side surface L after one or more reflections or refractions in the second layer Q2. 24 , with the fourth side L painted black 24 Alternatively, the non-projected light beam may be directed to the first layer Q1 after one or more reflections or refractions in the second layer Q2. The first layer Q1 then directs the incident non-projected light beam out of the prism structure 620, for example, at position X in the upper left corner of the diagram. This indicates that the optical system can direct the non-projected light beam to the blackened prism surface for absorption or out of the prism structure, thereby effectively suppressing the non-projected light beam in the optical system, reducing the probability of the non-projected light beam entering the projection lens and participating in imaging, and improving the projection contrast.

[0100] In an optional embodiment, the third layer Q3 can also reflect the non-projection light beam reflected from the display chip 630 to the fourth side surface L of the second layer Q2. 24For example, please continue to refer to FIG6 , even if the non-projection light beam reflected by the display chip 630 is not completely reflected back to the second layer Q2, but a portion (such as the non-projection light beam on the far right in the figure) is reflected to the third layer Q3, it can also be reflected by the third layer Q3 to the fourth side surface L painted black in the second layer Q2. 24 The third layer Q3 can be considered as a leak-proof layer for the second layer Q2, which is used to suppress the non-projection light beams that are not reflected by the second layer Q2, further eliminating the non-projection light beams in the optical system and reducing the influence of stray light in the optical system.

[0101] It should be noted that while FIG6 illustrates three illumination beams as an example, the actual illumination beams may be any one or more, and their directions may or may not be the same as shown. Furthermore, the display chip 630 can reflect each illumination beam to produce a projection beam and a non-projection beam. The projection beams and non-projection beams produced by reflecting the same illumination beam may have different emission angles, and the projection beams or non-projection beams produced by reflecting different illumination beams may have different positions but the same emission angle.

[0102] The following describes the various functional components and structures involved in FIG6 to provide an exemplary specific implementation solution.

[0103] 1. Light source

[0104] In one possible implementation, light source 610 may be a semiconductor light source. A semiconductor light source refers to a light source that emits light based on semiconductor materials. Specifically, it may include, but is not limited to, a laser diode (LD), a light-emitting diode (LED), or an organic light-emitting diode (OLED). Semiconductor light sources generally have advantages such as high electro-optical conversion efficiency, good reliability, high brightness, good color, low energy consumption, long life, and small size.

[0105] 2. Prism structure

[0106] It is understood that the prism structure 620 can be the prism structure shown in FIG. 4 , or other prism structures. For example, it can be composed of at least four prisms, and any of the at least four prisms can be a triangular prism, a quadrangular prism, or a pentaprism. It should be understood that any prism structure that can absorb non-projection light beams by coating the prism surface black is within the scope of protection of this application.

[0107] For ease of description, the following description uses the prism structure 620 as an example of the prism structure shown in FIG4 . In this case, the first layer Q1 of the prism structure 620 can be considered as the first triangular prism P1 in the prism structure shown in FIG4 , the second layer Q2 of the prism structure 620 can be considered as the quadrangular prism P2 in the prism structure shown in FIG4 , and the third layer Q3 of the prism structure 620 can be considered as the second triangular prism P3 in the prism structure shown in FIG4 .

[0108] In one possible implementation, referring to FIG4 , the angle between the first side surface of the prism P2 and the third side surface of the prism P2 may be 45°. As shown in FIG6 , this 45° angle can mirror the display chip 630, located below the prism structure 620, to the left of the prism structure 620 as shown. As a result, the mirrored display chip 630 and the projection lens 640, located to the right of the prism structure 620 as shown, are coaxial. Consequently, the projection light beam reflected by the display chip 630 is transmitted to the projection lens 640 in a straight line in the horizontal direction as shown. This reduces the probability of deformation or misalignment of the projection light beam, thereby improving the imaging quality of the projection lens 640.

[0109] In a further possible implementation, referring to FIG4 , the second side surface of the second triangular prism P3 is perpendicular to the third side surface of the second triangular prism P3. Thus, referring to FIG6 , the projection beam reflected by the quadrangular prism P2 enters the second triangular prism P3 in a horizontal direction as shown and then exits from the second side surface of the second triangular prism P3. Because the second side surface of the second triangular prism P3 is perpendicular to its third side surface, the second side surface of the second triangular prism P3 can be considered a vertical surface. This vertical surface can minimize the change in the exit direction of the horizontally incident projection beam.

[0110] In one possible implementation, referring to Figures 4 and 6 , the third side surface of the quadrangular prism P2 and the third side surface of the second triangular prism P3 can be located in the same plane, with the display chip 630 positioned below the plane as shown. Thus, according to the illustrated arrangement, the third side surface of the quadrangular prism P2 and the third side surface of the second triangular prism P3 constitute the bottom surface of the prism structure 620. Setting this flat surface not only enhances aesthetics, but also allows the light beam reflected from the display chip 630 to refract into the quadrangular prism P2 and the second triangular prism P3 at the same vertical position, facilitating the design of the light transmission path.

[0111] In one possible implementation, referring to Figures 4 and 6 , the third side surface of prism P2 is parallel to the fourth side surface of prism P2, and the area of ​​the third side surface of prism P2 is greater than the area of ​​the fourth side surface of prism P2. Thus, according to the arrangement shown in the figure, the third side surface of prism P2 serves as the bottom surface of prism structure 620, and the fourth side surface of prism P2 serves as the top surface of prism structure 620. The larger bottom surface area helps to make prism structure 620 more stable.

[0112] In a possible implementation, in addition to the fourth side L of the prism P2 24 In addition to being painted black, one or more other outer surfaces of the prism structure 620 that are not in the effective light path may also be painted black. For example, referring to FIG. 7a , considering that the light beam is basically not transmitted in the front-to-back direction as shown, the main surface in the front-to-back direction is ignored. The entire prism structure except for the fourth side surface L of the quadrangular prism P2 is painted black. 24 Other external surfaces may include the following five:

[0113] 1. First side surface L of the first prism P1 11 .

[0114] As shown in FIG7a, on the first side surface L of the first prism P1 11 In addition to the surface used to receive the illumination light beam, the other surfaces can be considered as surfaces corresponding to non-effective light paths and can be painted black.

[0115] It should be noted that although part of the non-projection light beam will also pass through the first side surface L of the first prism P1 11 For example, in the aforementioned optical system design, part of the non-projection light beam will be on the first side L shown in FIG7a. 11 However, after the position is painted black, the non-projection light beam directed to this position can be directly absorbed by the blackened surface without being guided out again. In other words, the first side surface L of the first prism P1 11 The blackening operation does not affect the effect of eliminating the non-projection light beam in the prism structure, but only changes the original method of deriving the non-projection light beam into a method of absorbing the non-projection light beam.

[0116] 2. The third side surface L of the first prism P1 13 .

[0117] As shown in FIG7a, on the third side L of the first prism P1 13 In the embodiment, since no illumination beam or projection beam is irradiated to the surface, the surface can be entirely painted black.

[0118] 3. The third side L of the prism P2 23 .

[0119] As shown in FIG7a, on the third side L of the prism P2 23 In addition to the surface used to guide the illumination light beam to the display chip 630 and the surface used to receive the projection light beam and non-projection light beam reflected by the display chip 630, other surfaces can be considered as surfaces corresponding to non-effective light paths and can be painted black.

[0120] Optionally, considering the third side L of the quadrangular prism P223 Most of the position is occupied by the effective light path, and it may not be easy to find the position of the non-effective light path part. Therefore, in some implementations, the surface may not be painted black to reduce the difficulty of manufacturing the prism.

[0121] Alternatively, considering that the non-projection light beam reflected by the display chip 630 is an invalid light beam for projection, in some implementations, the third side surface L of the prism P2 may be 23 The portion of the surface that receives the non-projection light beam reflected by the display chip 630 but does not receive the illumination light beam and the projection light beam is painted black, as shown in FIG7b. In this way, part of the non-projection light beam reflected by the display chip 630 can be directly reflected by the third side surface L of the prism P2. 23 The black-painted portion is absorbed and does not enter the prism P2. In this way, the non-projection light beam can be suppressed before it is reflected into the prism P2, thereby reducing the non-projection light beam entering the prism structure 620, thereby reducing the difficulty of eliminating the non-projection light beam in the prism structure 620.

[0122] 4. The third side surface L of the second prism P3 33 .

[0123] As shown in FIG7a, on the third side L of the second prism P3 33 In the figure, except for the part of the surface used to receive the non-projection light beam reflected by the display chip 630, the other surfaces can be considered as surfaces corresponding to non-effective light paths, and such surfaces can be painted black.

[0124] Optionally, considering that the non-projection light beam reflected by the display chip 630 is an invalid light beam for projection, and the third side surface L of the second prism P3 33 Only the reflected non-projection light beam will be received on the side surface, and no projection light beam will be irradiated to the side surface. Therefore, in some implementations, the entire third side surface of the second prism P3 can be directly painted black. 33 , please refer to FIG7b. In this way, even if part of the non-projection light beam reflected by the display chip 630 is not reflected to the third side surface L of the prism P2 23 Instead, it is reflected to the third side L of the second prism P3 33 The third side L of the second prism P3 can also be directly painted black. 33 The non-projection light beam is absorbed and does not enter the second prism P3, so that the non-projection light beam can be suppressed before it is reflected into the second prism P3, which can reduce the non-projection light beam entering the second prism P3 and further reduce the difficulty of eliminating the non-projection light beam in the prism structure 620.

[0125] 5. Second side surface L of the second prism P3 32 .

[0126] As shown in FIG7a, on the second side surface L of the second prism P3 32 On the left, except for the portion of the surface used to direct the projection beam toward projection lens 640, the remaining surfaces can be considered as surfaces not corresponding to the effective optical path and can be painted black. Alternatively, since most of the second side surface is used to direct the projection beam, it may be difficult to locate the portion not corresponding to the effective optical path. Therefore, to reduce manufacturing difficulty, this surface can be left unpainted.

[0127] In the above implementation, by blackening all the surfaces of the entire prism structure through which no effective light beam passes, the ineffective light beams (such as non-projection light beams) projected onto these surfaces can be directly absorbed by these blackened surfaces, thereby suppressing the reflection or refraction of the ineffective light beams in the prism structure as much as possible, and reducing the probability of generating stray light in the projection lens.

[0128] 3. Display Chip

[0129] In one possible implementation, the display chip 630 can be used to modulate the illumination light beam introduced by the prism structure 620 to obtain image light carrying image information. Specifically, the display chip 630 can perform spatial phase modulation on the illumination light beam introduced by the prism structure 620 to obtain the aforementioned projection light beam and non-projection light beam with different exit angles. The display chip 630 may typically include hundreds of thousands or even millions of micro-lenses, each micro-lens corresponding to a pixel on the image. The more micro-lenses there are, the higher the resolution of the image loaded by the display chip 630. Currently commonly used display chips 630 may include, but are not limited to: digital micromirror devices (DMDs), liquid crystal display (LCD) chips, liquid crystal on silicon (LCOS) chips, or laser beam scanning (LBS) displays.

[0130] Taking the DMD chip as an example, each microlens on it can be at different deflection angles at the same time. Different deflection angles correspond to different deflection states of the DMD chip, which can include "on", "off", and "flat" states. Specifically, for a frame of image, some areas are brighter and some areas are darker. Pixels on the image with brightness greater than or equal to the brightness threshold are called bright spots, and pixels with brightness less than the brightness threshold are called dark spots. Please refer to Figure 8a. When projecting an image, the DMD chip will configure the deflection angle of the microlens corresponding to the bright spot to the deflection angle corresponding to the "on" state, and configure the deflection angle of the microlens corresponding to the dark spot to the deflection angle corresponding to the "off" state. Furthermore, after projecting one frame of image, when projecting the next frame of image, the bright and dark areas on the image may change, resulting in changes in the bright and dark spots on the image. Some previous bright spots may become dark spots, and some previous dark spots may become bright spots. In this case, the DMD chip will switch the deflection angle of the microlens corresponding to the pixel that was previously a bright spot but is now a dark spot from the deflection angle corresponding to the "on" state to the deflection angle corresponding to the "off" state, and switch the deflection angle of the microlens corresponding to the pixel that was previously a dark spot but is now a bright spot from the deflection angle corresponding to the "off" state to the deflection angle corresponding to the "on" state according to the changes in these bright and dark spots. Normally, the deflection angle corresponding to the "on" state and the deflection angle corresponding to the "off" state are opposite to each other relative to the plane where the DMD chip is located. For example, please continue to refer to Figure 8a. Assume that the deflection angle corresponding to the "on" state is an angle rotated 12° counterclockwise relative to the plane where the DMD chip is located, and the deflection angle corresponding to the "off" state is an angle rotated 12° clockwise relative to the plane where the DMD chip is located. Then, whether switching from the deflection angle corresponding to the "on" state to the deflection angle corresponding to the "off" state, or switching from the deflection angle corresponding to the "off" state to the deflection angle corresponding to the "on" state, there will be a lying state in the middle, which can be understood as a state where the deflection angle is 0. In this state, the microlens lies flat on the plane where the DMD chip is located. This state is called the "flat" state.

[0131] Further, referring to FIG8b , assuming that when light (or a light beam) is incident on the DMD chip, microlens 1 on the DMD chip is at a deflection angle corresponding to the "on" state, microlens 2 is at a deflection angle corresponding to the "flat" state, and microlens 3 is at a deflection angle corresponding to the "off" state, then microlens 1 will reflect the incident light (or light beam) at the deflection angle corresponding to the "on" state, forming an "on" state light (or "on" state light beam), microlens 2 will reflect the incident light (or light beam) at the deflection angle corresponding to the "flat" state, forming a "flat" state light (or "flat" state light beam), and microlens 3 will reflect the incident light (or light beam) at the deflection angle corresponding to the "off" state, forming an "off" state light (or "off" state light beam). The "on" state light beam is the light beam required for projection and belongs to the projection light beam, while the "off" state light beam and the "flat" state light beam are light beams not required for projection and belong to the non-projection light beam.

[0132] Furthermore, taking light as an example, since the "on" state, "flat" state, and "off" state light are reflected from the same incident angle by micro-mirrors 1, 2, and 3 at different deflection angles, the three states of light have different exit angles relative to the plane where the DMD chip resides. For example, referring to Figure 8b , based on the deflection method shown, the exit angles of the three states of light satisfy the following relationship: exit angle α1 for "on" state light < exit angle α2 for "flat" state light < exit angle α3 for "off" state light.

[0133] Based on the above, in one possible implementation, the projected beam may include the beam reflected by the display chip 630 at a first deflection angle, and the non-projected beam may include the beam reflected by the display chip 630 at a second deflection angle and the beam reflected by the display chip 630 at a third deflection angle. The first, second, and third deflection angles correspond to three different deflection states of the display chip 630. For example, assuming that the display chip 630 is a DMD chip, ideally, only the beam corresponding to the bright spot should enter the projection lens for imaging, while beams other than the bright spot should not. Therefore, the first deflection angle may be the deflection angle corresponding to the aforementioned "on" state, the second deflection angle may be the deflection angle corresponding to the aforementioned "flat" state, and the third deflection angle may be the deflection angle corresponding to the aforementioned "off" state. In other words, the projected beam may include the aforementioned "on" state beam, and the non-projected beam may include the aforementioned "off" state beam and the aforementioned "flat" state beam.

[0134] Furthermore, the prism structure 620 can be used to suppress the "off" state light beam and the "flat" state light beam. For example, please refer to Figure 9, which exemplifies a schematic diagram of a light beam transmission path provided by the present application, wherein Figure 9 (A) shows the overall transmission path of the light beams in each state, and Figures 9 (B) to 9 (E) show the transmission paths of the light beams in each state. Specifically, Figure 9 (B) shows the transmission path of the illumination light beam, Figure 9 (C) shows the transmission path of the "on" state light beam, Figure 9 (D) shows the transmission path of the "flat" state light beam, and Figure 9 (E) shows the transmission path of the "off" state light beam. The transmission paths of the light beams in different states on the prism structure 620 and the display chip 630 are described in detail below in conjunction with Figures 9 (B) to 9 (E).

[0135] First, referring to FIG9 (B), the illumination light beam passes through the first triangular prism P1 and the quadrangular prism P2 in sequence, and then irradiates the display chip 630 at a certain incident angle. Specifically, the illumination light beam first irradiates the first side surface of the first triangular prism P1, is refracted on the first side surface of the first triangular prism P1, enters the interior of the first triangular prism P1, and is transmitted internally to the second side surface of the first triangular prism P1. Thereafter, the illumination light beam is refracted out of the second side surface of the first triangular prism P1, passes through the thin air layer between the second side surface of the first triangular prism P1 and the first side surface of the quadrangular prism P2, is refracted on the first side surface of the quadrangular prism P2, enters the interior of the quadrangular prism P2, and is transmitted inside the quadrangular prism P2 to the third side surface of the quadrangular prism P2. Thereafter, the illumination light beam is refracted out of the third side surface of the quadrangular prism P2, and after being transmitted through the intermediate air layer, it hits the display chip 630.

[0136] Next, referring to FIG. 9 (C), on the display chip 630, the micro-lens (not shown in the figure, refer to FIG. 8b ) at the deflection angle corresponding to the "on" state reflects the illumination light beam into an "on" state light beam. After one or more reflections or one or more refractions in the quadrangular prism P2, the "on" state light beam enters the triangular prism P3 and is then directed to the projection lens 640 on the second side surface of the triangular prism P3. Optionally, according to the arrangement shown in the figure, the "on" state light beam reflected by the display chip 630 can be reflected along the vertical direction shown in the figure to the third side surface of the quadrangular prism P2, that is, the exit angle of the central light in the "on" state light beam on the display chip 630 is 0. The "on" state light beam is refracted on the third side surface of the prism P2 and enters the interior of the prism P2, and is transmitted inside the prism P2 to the first side surface of the prism P2, and then is totally reflected on the first side surface of the prism P2 to the second side surface of the prism P2, and is refracted out on the second side surface of the prism P2, and after passing through the thinner air layer between the second side surface of the prism P2 and the first side surface of the second prism P3, it is refracted on the first side surface of the second prism P3 and enters the interior of the second prism P3, and then is transmitted inside the second prism P3 to the second side surface of the second prism P3, and is refracted out from the second side surface of the second prism P3 and enters the projection lens 640. It can be seen that in this optical transmission path, the "on" state light beam reflected into the prism P2 can be directly reflected by the prism P2 into the second prism P3, and then directly refracted by the second prism P3 into the projection lens 640. This transmission method can guide the "on" state light beam to the projection lens 640 through a shorter optical path, which helps to reduce energy waste of the projection light beam.

[0137] Furthermore, referring to FIG9 (D), on the display chip 630, the micro-mirror (not shown in the figure, refer to FIG8b) at the deflection angle corresponding to the "flat" state reflects the illumination light beam into a "flat" state light beam. After one or more reflections or one or more refractions in the prism P2, part of the "flat" state light beam is guided to the fourth side surface L painted black on the prism P2. 24is absorbed, and part of it is reflected to the first prism P1 and then exported to the prism structure 620. Optionally, according to the arrangement shown in the figure, the "flat" state light beam reflected by the display chip 630 can be reflected to the third side surface of the prism P2 along the upper right direction of the figure, that is, the exit angle of the "flat" state light beam on the display chip 630 is greater than the exit angle of the "on" state light beam on the display chip 630. The "flat" state light beam is refracted on the third side surface of the prism P2 and enters the interior of the prism P2, most of which (such as the two "flat" state light beams on the left and the left part of the "flat" state light beam on the right) are transmitted inside the prism P2 to the first side surface of the prism P2, and a small part (such as the right part of the "flat" state light beam on the right) is directly incident on the fourth side surface L of the prism P2 inside the prism P2. 24 The "flat" light beam refracted onto the first side surface of the prism P2 is totally reflected on the first side surface of the prism P2 to the second side surface of the prism P2, and then totally reflected on the second side surface of the prism P2, with most of it being reflected to the fourth side surface L of the prism P2. 24 The light beam is absorbed on the surface of the prism P2, and a small portion is reflected back to the first side surface of the prism P2, and then refracted out from the first side surface of the prism P2. After passing through the thin air layer between the first side surface of the prism P2 and the second side surface of the first triangular prism P1, it is refracted on the second side surface of the first triangular prism P1 and enters the interior of the first triangular prism P1. It is transmitted from the interior of the first triangular prism P1 to the first side surface of the first triangular prism P1 and refracted out from the first side surface of the first triangular prism P1, as shown in the figure at position X. It can be seen that in this optical transmission path, the "flat" state light beam reflected into the prism P2 can be guided to the blackened surface for absorption or guided out of the prism structure through two reflections in the prism P2, so that the transmission path of the "flat" state light beam from entering the prism P2 to being eliminated is shorter, which can reduce the probability of stray light introduced by multiple reflections or refractions of the "flat" state light beam in the prism P2.

[0138] Finally, referring to FIG. 9 (E), on the display chip 630, the micro-mirror (not shown in the figure, refer to FIG. 8b ) at the deflection angle corresponding to the "off" state reflects the illumination beam into an "off" state beam. The "off" state beam undergoes one or more reflections or one or more refractions in the quadrangular prism P2 and the second triangular prism P3, and is then directed to the fourth side surface L of the quadrangular prism P2, which is painted black. 24Absorbed on. Optionally, according to the arrangement shown in the figure, the "off" state light beam reflected by the display chip 630 is also reflected along the upper right direction of the figure to the third side surface of the prism P2, and the exit angle of the "off" state light beam on the display chip 630 is greater than the exit angle of the "flat" state light beam on the display chip 630. Most of the "off" state light beams (such as the two "off" state light beams on the left) are refracted on the third side surface of the prism P2 and enter the interior of the prism P2, and a small part (such as the "off" state light beam on the right) is refracted on the third side surface of the second prism P3 and enters the interior of the second prism P3. Among them, most of the "off" state light beams that enter the interior of the prism P2 (such as the right part of the "off" state light beam on the left and the left part of the "off" state light beam in the middle) are directly incident on the fourth side surface L of the prism P2. 24 The "off" state light beam transmitted to the first side surface of the prism P2 is totally reflected on the first side surface, part of it is reflected to the second side surface of the prism P2, and the other part is reflected to the fourth side surface L of the prism P2. 24 The "off" state light beam reflected from the first side surface of the prism P2 and the "off" state light beam refracted from the third side surface of the prism P2 enter the second side surface of the prism P2 and are totally reflected from the second side surface of the prism P2 to the fourth side surface L of the prism P2. 24 Also, part of the "off" state light beam that enters the interior of the second prism P3 is directly transmitted to the second side surface of the second prism P3, and the other part is totally reflected on the first side surface of the second prism P3 to the second side surface of the second prism P3. These two parts of the "off" state light beam are totally reflected on the second side surface of the second prism P3 to the first side surface of the second prism P3, and refracted from the first side surface of the second prism P3. After passing through the thin air layer between the first side surface of the second prism P3 and the second side surface of the quadrangular prism P2, they are refracted on the second side surface of the quadrangular prism P2 and enter the interior of the quadrangular prism P2. Thereafter, they are transmitted from the interior of the quadrangular prism P2 to the fourth side surface L of the quadrangular prism P2. 24 It can be seen that in this optical transmission path, the "off" state light beam reflected into the second prism P3 can be guided to the blackened surface of the quadrangular prism P2 through one or two reflections in the second prism P3. As a result, the transmission path of the "off" state light beam from entering the second prism P3 to being eliminated is shorter, thus reducing the probability of stray light introduced by the "off" state light beam being reflected or refracted multiple times in the second prism P3.

[0139] According to the above content, it can be seen that by designing the above-mentioned optical system, the "off" state light beam and the "flat" state light beam reflected by the display chip can be guided to the blackened surface for absorption or guided out of the prism structure through one or more reflections or refractions in the prism structure. In this way, by suppressing both the "off" state light beam and the "flat" state light beam, two invalid light beams, the "off" state light beam and the "flat" state light beam can be avoided from entering the projection lens in large quantities to form stray light, thereby allowing the relatively pure "on" state light beam to enter the projection lens 640, thereby improving the contrast of the projection imaging.

[0140] It should be noted that, in the above description, the exit angle of the "flat" state light beam on the display chip 630 is greater than the exit angle of the "on" state light beam on the display chip 630, and the exit angle of the "off" state light beam on the display chip 630 is greater than the exit angle of the "flat" state light beam on the display chip 630. This can be understood as follows: the exit angle of the "flat" state light beam with the smallest exit angle on the display chip 630 is greater than the exit angle of the "on" state light beam with the largest exit angle on the display chip 630, and the exit angle of the "off" state light beam with the smallest exit angle on the display chip 630 is greater than the exit angle of the "flat" state light beam with the largest exit angle on the display chip 630. In this way, there is no overlap between the angles of the "on" state light beam, the "flat" state light beam, and the "off" state light beam reflected from the display chip 630, thereby leaving a certain interval between the three light beams, as shown in FIG. 9 (A). It can be seen that it is precisely because of this non-overlapping angular characteristic that support is provided for separating the three-state light beams through reflection or refraction in the prism structure 620 .

[0141] Furthermore, according to the arrangement shown in FIG9 , after being totally reflected by the first side surface of prism P2, the magnitude relationship between the incident angles of the "on" state light beam, the "flat" state light beam, and the "off" state light beam upon the second side surface of prism P2 can be maintained to be the same as the magnitude relationship between the incident angles of the "on" state light beam, the "flat" state light beam, and the "off" state light beam upon reflection from display chip 430. In other words, the incident angle of the "on" state light beam upon the second side surface of prism P2 is smaller than the incident angle of the "flat" state light beam upon the second side surface of prism P2, and the incident angle of the "flat" state light beam upon the second side surface of prism P2 is smaller than the incident angle of the "off" state light beam upon the second side surface of prism P2. Thus, the smaller the incident angle of the "on" state light beam upon the second side surface of prism P2, the more likely it is to be smaller than the critical angle for total internal reflection corresponding to the second side surface of prism P2, and the easier it is to achieve refraction of the "on" state light beam upon the second side surface of prism P2. Furthermore, the greater the incident angle of the "off" state light beam and the "flat" state light beam on the second side surface of the prism P2, the more likely it is that the incident angle will exceed the critical angle of total internal reflection corresponding to the second side surface of the prism P2, and the easier it will be to achieve total internal reflection of the "off" state light beam and the "flat" state light beam on the second side surface of the prism P2. It can be seen that by designing the above-mentioned optical system so that the incident angle of the projection light beam on the second side surface of the prism P2 is smaller than the incident angle of the non-projection light beam on the second side surface of the prism P2, it is helpful to utilize the critical angle of total internal reflection of the second side surface of the prism P2 to separate the projection light beam and the non-projection light beam.

[0142] Furthermore, to realize the optical transmission path shown in FIG. 9 in the prism structure 620 , the prism structure 620 needs to have some other features, which will be described in detail below.

[0143] In one possible implementation, please continue to refer to Figure 9. In this optical system, the first prism P1, the quadrangular prism P2, and the second prism P3 are optically dense media, and air is an optically rarer medium. Therefore, when a light beam enters the air from a side surface of any prism, it is equivalent to the light beam entering the optically rarer medium from an optically dense medium. This side surface will correspond to a critical angle for total internal reflection. For example, according to the optical transmission path shown in Figure 9, the side surfaces corresponding to the critical angle for total internal reflection may include the following five side surfaces:

[0144] a1, the second side surface of the first prism P1.

[0145] Specifically, please refer to (B) in Figure 9. The illumination light beam will be refracted from the second side surface of the first prism P1 into the air layer between the second side surface of the first prism P1 and the first side surface of the quadrangular prism P2. In other words, the illumination light beam can pass through the second side surface of the first prism P1 without being totally reflected by the second side surface. Therefore, according to the definition of total reflection in the aforementioned term explanation section, the incident angle of the illumination light beam on the second side surface of the first prism P1 is less than the critical angle of total reflection corresponding to the second side surface of the first prism P1. Among them, the critical angle of total reflection corresponding to the second side surface of the first prism P1 is: n p0 is the refractive index of air, n p12 is the refractive index of the material near the second side surface of the first prism P1.

[0146] a2, the third side surface of the quadrangular prism P2.

[0147] Specifically, referring to (B) in FIG9 , the illumination light beam will be emitted from the third side surface of the prism P2 into the air between the third side surface of the prism P2 and the display chip 630. In other words, the illumination light beam can pass through the third side surface of the prism P2 without being totally reflected by the third side surface. Therefore, according to the definition of total reflection in the aforementioned term explanation section, the incident angle of the illumination light beam on the third side surface of the prism P2 is less than the critical angle of total reflection corresponding to the third side surface of the prism P2. Among them, the critical angle of total reflection corresponding to the third side surface of the prism P2 is: n p0 is the refractive index of air, n p23 is the refractive index of the material near the third side surface of the prism P2.

[0148] a3, a first side surface of the quadrangular prism P2.

[0149] Specifically, please refer to (C) to (E) in Figure 9. The projection light beam (such as the "on" state light beam) and the non-projection light beam (such as the "flat" state light beam and the "off" state light beam) reflected from the display chip 630 will be totally reflected at the first side surface of the prism P2. Most of the non-projection light beam (referred to as the first portion of the non-projection light beam) reflected from the second side surface of the prism P2 will be totally reflected at the first side surface of the prism P2, and a small portion of the non-projection light beam (referred to as the second portion of the non-projection light beam) will be refracted at the first side surface of the prism P2 into the air layer between the first side surface of the prism P2 and the second side surface of the first prism P1. In other words, the first portion of the non-projection light beam and all the light beams reflected by the display chip 630 can be totally reflected by the first side surface of the prism P2, while the second portion of the non-projection light beam can pass through the first side surface of the prism P2 without being totally reflected by the first side surface. Therefore, according to the definition of total internal reflection in the aforementioned terminology explanation section, the incident angle of the first portion of the non-projection light beam and the entire light beam reflected by the display chip 630 upon the first side surface of the quadrangular prism P2 is greater than or equal to the critical angle of total internal reflection corresponding to the first side surface of the quadrangular prism P2, and the incident angle of the second portion of the non-projection light beam upon the first side surface of the quadrangular prism P2 is less than the critical angle of total internal reflection corresponding to the first side surface of the quadrangular prism P2. The critical angle of total internal reflection corresponding to the first side surface of the quadrangular prism P2 is: n p0 is the refractive index of air, n p21 is the refractive index of the material near the first side surface of the prism P2.

[0150] a4, the second side surface of the quadrangular prism P2.

[0151] Specifically, please refer to Figure 9 (C) to Figure 9 (E). The projection light beam reflected from the first side surface of the prism P2 (such as the "on" state light beam) will be refracted at the second side surface of the prism P2 and enter the air layer between the second side surface of the prism P2 and the first side surface of the second prism P3, while the non-projection light beam reflected from the first side surface of the prism P2 (such as the "flat" state light beam and the "off" state light beam) will be totally reflected at the second side surface of the prism P2. In other words, the projection light beam can pass through the second side surface of the prism P2 without being totally reflected by the second side surface, while the non-projection light beam is totally reflected by the second side surface of the prism P2. Therefore, according to the definition of total reflection in the aforementioned term explanation section, the incident angle of the projection light beam irradiating the second side surface of the prism P2 is less than the critical angle of total reflection corresponding to the second side surface of the prism P2, and the incident angle of the non-projection light beam irradiating the second side surface of the prism P2 is greater than or equal to the critical angle of total reflection corresponding to the second side surface of the prism P2. Among them, the critical angle of total reflection corresponding to the second side surface of the prism P2 is: n p0 is the refractive index of air, np22 is the refractive index of the material near the second side surface of the prism P2.

[0152] It can be understood that the projection beam contains multiple projection light rays, and the incident angle of the projection light beam on the second side surface of the prism P2 is less than the critical angle of total reflection corresponding to the second side surface of the prism P2. It can be considered that the incident angle of the projection light with the largest incident angle in the projection beam on the second side surface of the prism P2 is less than the critical angle of total reflection corresponding to the second side surface of the prism P2. Similarly, the non-projection light beam contains multiple non-projection light rays, and the incident angle of the non-projection light beam on the second side surface of the prism P2 is greater than or equal to the critical angle of total reflection corresponding to the second side surface of the prism P2. It can be considered that the incident angle of the non-projection light with the smallest incident angle in the non-projection light beam on the second side surface of the prism P2 is greater than or equal to the critical angle of total reflection corresponding to the second side surface of the prism P2.

[0153] a5, second side surface of the second prism P3.

[0154] Specifically, please refer to (C) and (E) in FIG9 . The non-projection light beam (such as the "off" state light beam) reflected from the display chip 630 will be totally reflected at the second side surface of the second prism P3, while the projection light beam (such as the "on" state light beam) reflected from the second side surface of the prism P2 will be refracted at the second side surface of the second prism P3 to the projection lens 640. In other words, the non-projection light beam can be totally reflected by the second side surface of the second prism P3, while the projection light beam can pass through the second side surface of the second prism P3 without being totally reflected by the second side surface. Therefore, according to the definition of total reflection in the aforementioned term explanation section, the incident angle of the non-projection light beam irradiating the second side surface of the second prism P3 is greater than or equal to the critical angle of total reflection corresponding to the second side surface of the second prism P3, and the incident angle of the projection light beam irradiating the second side surface of the second prism P3 is less than the critical angle of total reflection corresponding to the second side surface of the second prism P3. Among them, the critical angle of total reflection corresponding to the second side surface of the second prism P3 is: n p0 is the refractive index of air, n p32 is the second n of the second prism P3 p32 is the refractive index of the material near the second side surface of the second prism P3.

[0155] Furthermore, in addition to the five sides mentioned above, on any of the remaining sides, the light beam will be refracted from the air through the side and enter the corresponding prism. For example, according to the light path transmission path shown in Figure 9, the remaining sides may include the following five sides:

[0156] b1, a first side surface of the first prism P1.

[0157] Specifically, referring to FIG. 9 (B), the illumination light beam transmitted through the air will be refracted from the first side surface of the first prism P1 to the interior of the first prism P1. In other words, the illumination light beam can pass through the first side surface of the first prism P1 without being totally reflected by the first side surface.

[0158] b2, a first side surface of the quadrangular prism P2.

[0159] Specifically, please refer to (B) in Figure 9. The illumination light beam emitted from the second side surface of the first prism P1 will be refracted from the first side surface of the quadrangular prism P2 to the inside of the quadrangular prism. In other words, the illumination light beam can pass through the first side surface of the quadrangular prism P2 without being totally reflected by the first side surface.

[0160] b3, the third side surface of the quadrangular prism P2.

[0161] Specifically, please refer to (C) to (E) in Figure 9. The projection light beam (such as the "on" state light beam) and the non-projection light beam (such as the "flat" state light beam and the "off" state light beam) reflected from the display chip 630 will be refracted from the third side surface of the prism P2 to the inside of the prism. In other words, both the projection light beam and the non-projection light beam can pass through the third side surface of the prism P2 without being totally reflected by the third side surface.

[0162] b4, the first side surface of the second prism P3.

[0163] Specifically, please refer to (C) in Figure 9. The projection light beam reflected from the second side surface of the prism P2 (such as the "on" state light beam) will be refracted from the first side surface of the second prism P3 to the interior of the second prism P3. In other words, the projection light beam can pass through the first side surface of the second prism P3 without being totally reflected by the first side surface.

[0164] b5, the third side surface of the second prism P3.

[0165] Specifically, please refer to (E) in Figure 9. The non-projection light beam (such as the "off" state light beam) reflected from the display chip 630 will be refracted from the third side surface of the second prism P3 to the interior of the second prism P3. In other words, the non-projection light beam can pass through the third side surface of the second prism P3 without being totally reflected by the third side surface.

[0166] It is understood that a prism can usually be made uniformly of the same material. In this case, the refractive index of each side of the prism is the same. For example, when the first triangular prism P1 is made uniformly of the same material, the refractive index n of the first side of the first triangular prism P1 mentioned above is p11 , the refractive index n of the second side surface of the first prism P1 p12 , the refractive index n of the third side surface of the first triangular prism P1p13 are the same, the refractive index of any side surface of the first prism P1 can also be called the refractive index n of the first prism P1 p1 Correspondingly, when the entire prism P2 is made of the same material, the refractive index n of the first side surface of the prism P2 involved in the above content is p21 , the refractive index n of the second side surface of the prism P2 p22 , the refractive index n of the third side surface of the prism P2 p23 The refractive index of any side surface of the prism P2 can also be called the refractive index n of the prism P2. p2 Furthermore, when the second prism P3 is made of the same material, the refractive index n of the first side surface of the second prism P3 mentioned above is p31 , the refractive index n of the second side surface of the second prism P3 p32 , the refractive index n of the third side surface of the second prism P3 p33 The refractive index of any side surface of the second prism P3 can also be called the refractive index n of the second prism P3. p3 .

[0167] It can be understood that, based on the above, the transmission path of the light beam in each state in the prism structure 620 is related to the critical angle of total reflection corresponding to each prism side surface in the prism structure 620, and the critical angle of total reflection of the prism side surface is determined by the refractive index of air and the refractive index of the material near the prism side surface, wherein the refractive index of air is fixed. Therefore, it can be considered that the transmission path of the light beam in each state in the prism structure 620 is related to the refractive index of each prism side surface in the prism structure 620. Based on this, in an optional implementation, the material with the corresponding refractive index can be selected with reference to the light beam transmission path required to be achieved on any side surface of each prism to make the side surface and the nearby material of the prism. For example, taking the second side of the prism P2 as an example, the incident angle of the projection beam irradiated on the second side of the prism P2 and the incident angle of the non-projection beam irradiated on the second side of the prism P2 can be obtained by experiment or calculation. Then, based on the content described in Section a4 above that the incident angle of the projection beam irradiated on its second side is less than the critical angle of total reflection and the incident angle of the non-projection beam irradiated on its second side is greater than or equal to the critical angle of total reflection, the range of the critical angle of total reflection that can achieve this function is determined. Then, based on the correlation between the critical angle of total reflection, the refractive index of air and the refractive index corresponding to the second side of the prism P2 given in Section a4 above, the refractive index range corresponding to the second side of the prism P2 is calculated. Then, one or more materials with a refractive index within this range are selected to make the second side of the prism P2 and the nearby materials, so that the second side of the prism P2 can achieve the effect of refracting the projection beam and reflecting the non-projection beam. Alternatively, if the prism materials are consistent, the materials with corresponding refractive indices can be selected to make the entire prism with reference to the beam transmission path required to be achieved on each side of each prism. For example, still taking the prism P2 as an example, you can also first calculate the three refractive index ranges that meet the requirements of the first side of the prism P2 for refracting illumination light, the second side of the prism P2 for reflecting projection light beams and non-projection light beams, and the third side of the prism P2 for refracting projection light beams and reflecting non-projection light beams according to the method of calculating the refractive index range corresponding to any prism side given above. Then, select one or more materials whose refractive index is within the common range of these three refractive index ranges to make the entire prism P2, so that the produced prism P2 can meet the requirements of refracting or reflecting light beams on each side.

[0168] Optionally, the transmission path of each state light beam in the prism structure 620 is also related to the inclination angle of each prism side in the prism structure 620. Therefore, the inclination angle of the prism side can also be designed with reference to the transmission path of each state light beam in the prism structure 620. It can be understood that for the same incident light beam, the greater the inclination angle of the side, the greater the incident angle of the incident light beam on the side. For example, still taking the second side of the prism P2 as an example, Figure 10 exemplarily shows a schematic diagram of the same light irradiating the second side with different inclination angles. When the inclination angle of the second side of the prism P2 is γ1 as shown in Figure 10 (A), the incident angle of a certain light reflected from the first side of the prism P2 on the second side of the prism P2 is β1, but when the inclination angle of the second side of the prism P2 becomes smaller to γ2 as shown in Figure 10 (B), the incident angle of the same light irradiating on the second side of the prism P2 becomes larger to β2. It can be seen that as the inclination angle of the second side surface of prism P2 increases, the incident angle of the same light ray on the second side surface of prism P2 also increases, and the probability that the incident angle exceeds the critical angle for total internal reflection corresponding to the second side surface of prism P2 also increases. Therefore, the probability that the light ray is totally reflected by the second side surface of prism P2 instead of being refracted also increases. Therefore, when designing the second side surface of prism P2, the corresponding inclination angle on the second side surface of prism P2 can be selected with reference to the incident angle of each light beam on the second side surface of prism P2, the critical angle for total internal reflection of the second side surface of prism P2, and the reflection or refraction path of each light beam on the second side surface of prism P2. For example, in one possible implementation, the incident angles of the projection beam and the non-projection beam on the second side surface of the prism P2 at various different tilt angles can be first tested experimentally, and then an inclination angle that satisfies the conditions that the incident angle of the projection beam is less than the critical angle of total reflection corresponding to the second side surface of the prism P2 and the incident angle of the non-projection beam is greater than or equal to the critical angle of total reflection corresponding to the second side surface of the prism P2 is selected from the various tilt angles. Then, an inclination angle is selected from these inclination angles that meet the conditions as the inclination angle of the second side surface of the prism. The selected inclination angle can be a randomly selected one, or one of the angle values ​​selected from those inclination angles that meet the conditions, or one of the smallest or largest angle values ​​selected from those inclination angles that meet the conditions, and so on. There is no specific limitation.

[0169] In one possible implementation, the refractive index of the quadrangular prism P2 is the same as the refractive index of the second triangular prism P3. For example, referring to (C) in FIG9 , the "on" state light beam will sequentially pass through the second side surface of the quadrangular prism P2, the air, and the first side surface of the second triangular prism P3 into the second triangular prism P3. Since the refractive index of the quadrangular prism P2 is the same as the refractive index of the second triangular prism P3, it is equivalent to the "on" state light beam first being refracted from the second side surface of the quadrangular prism P2 into the air at this refractive index, and then being refracted from the air into the first side surface of the second triangular prism P3 at the opposite refractive index. Therefore, the direction in which the "on" state light beam is refracted into the second triangular prism P3 can remain consistent with the direction in which it is emitted from the quadrangular prism P2. In this way, the second side surface of the quadrangular prism P2 and the first side surface of the second triangular prism P3, which are bonded together, are equivalent to the effect of transparent glass for the transmission of the "on" state light beam, and can be used to keep the main transmission direction of the "on" state light beam unchanged.

[0170] It should be noted that the refractive index of the first triangular prism P1 may be the same as or different from the refractive index of the quadrangular prism P2 and the second triangular prism P3, and there is no specific limitation thereto.

[0171] In addition, FIG9 is merely an example of a possible optical transmission method, and other optical transmission methods may also be present in actual optical systems. For example, when the placement of the display chip 630 changes, the position and angular relationship between the projection light beam and the non-projection light beam reflected by the display chip 630 into the prism structure 620 may also change. However, as long as the prism structure 620 is designed so that the non-projection light beam reflected by the display chip 630 can be guided to the blackened surface for absorption or guided out of the prism structure 620 through one or more reflections or refractions in the prism structure 620, and the projection light beam reflected by the display chip 630 can be guided to the projection lens 640 through one or more reflections or refractions in the prism structure 620, then such optical systems are within the scope of protection of this application, and this application does not impose specific limitations on this.

[0172] 4. Projection Lens

[0173] Optionally, the projection lens 640 can be used to diverge the projection light beam from the prism structure 620 to achieve image magnification. The projection lens 640 may include one or more lenses. For example, FIG11 exemplarily shows a schematic structural diagram of a projection lens. This example uses the projection lens 640 as an example including 10 lenses, but the specific number of lenses included can be set according to the projection requirements of the actual scene. For example, if the requirements for projection clarity and projection field of view are high, more lenses can be configured in the projection lens. If the requirements for projection clarity and projection field of view are low, fewer lenses can be configured in the projection lens.

[0174] In an optional embodiment, in order to save the volume of the optical system, the lens closest to the prism structure 620 in the projection lens 640 can be fixedly arranged or integrated with the prism structure 620. Among them, the lens closest to the prism structure 620 in the projection lens 640 is also called the last lens of the projection lens 640, and specifically can be the lens closest to the second prism P3 in the projection lens 640. This lens can be fixedly arranged or integrated with the second prism P3. For example, referring to Figure 12, in one embodiment, the last lens can be attached to the third side surface of the second prism P3. Alternatively, in another embodiment, the first side surface, the third side surface, the first principal surface, and the second principal surface of the second prism P3 can be made on a piece of glass, and the remaining surface can be made into the right side surface of the last lens shown in the figure.

[0175] In a further optional embodiment, please continue to refer to Figure 12. When the second prism P3 and the last lens are fixedly arranged, the last lens can be set to a plane relative to a surface of the second prism P3. For example, the left side of the last lens shown in the figure can be controlled to be a plane. Specifically, it can be controlled to be a plane that is parallel to and of the same size as the third side surface (i.e., the right side shown in the figure) of the second prism P3. In this way, when fixing the second prism P3 and the last lens, the right side of the last lens shown in the figure can be directly attached to the left side of the second prism P3 shown in the figure, and glue can be used to bond them together, making it easier to fix.

[0176] It can be understood that the back focal length of the optical system is the distance the projection beam travels from the plane where the display chip 630 is located to the last lens element of the projection lens 640. For example, referring to FIG13 , this can be specifically the sum of the distance h1 from the projection beam reflected from the plane where the display chip 630 is located to the second side surface of the quadrangular prism P2, the distance h2 from the projection beam reflected from the second side surface of the quadrangular prism P2 to the second side surface of the second triangular prism P3, and the distance from the second side surface of the second triangular prism P3 to the last lens element of the projection lens 640. When the last lens element is fixed or integrated with the second triangular prism P3, the distance the projection beam travels from the second side surface of the second triangular prism P3 to the last lens element of the projection lens 640 is zero. Compared to a solution in which the last lens element is not fixed or integrated with the second triangular prism P3, this approach can reduce the back focal length of the optical system, thereby reducing the design difficulty of the back focal length system.

[0177] The above describes the transmission paths of different light beams in an optical system including a prism structure. It should be understood that the optical system may include other structures in addition to the prism structure. For example, in some embodiments, the optical system may also include one or more lenses, which can be used to homogenize the illumination beam emitted by the light source 610 so that the energy of the illumination beam is evenly distributed on the display chip 630.

[0178] In addition, the light beam referred to in this application refers to a collection of light rays comprising multiple light rays. The multiple light rays can be evenly or unevenly distributed. Although many of the drawings in this application depict light beams in a uniform distribution, this is solely for ease of presentation and does not constitute a limitation of this application.

[0179] Based on the structural and functional principles of the prism structure and optical system described above, the present application also provides an optical display device. The optical display device may include the optical system of any of the above embodiments, and further, may include a display chip and a projection lens, such as the aforementioned display chip 630 and projection lens 640. The display chip can be used to reflect the illumination beam introduced from the prism structure at different deflection angles, and the projection lens can be used to project a magnified image based on the projection beam introduced by the prism structure.

[0180] In one possible implementation, the optical display device may further include a light source, such as the light source 610 in Figure 6 , wherein the light source is configured to emit an illumination beam toward the prism structure 610. Specifically, the illumination beam may be emitted toward the first side surface of the first prism P1.

[0181] In one possible implementation, the optical display device may further include a display screen, which may be used to display the magnified image from the projection lens. The display screen generally refers to a screen without a backlight source, which is used to receive external light and display an image. Specifically, it may be a display curtain or a display screen, such as a movie screen. Alternatively, the display screen may also have a backlight source, but may also receive light from the outside and display an image. In this case, the display screen may be a liquid crystal display (LCD), a light-emitting diode (LED) display screen, an organic light-emitting diode (OLED) display screen, or a micro light-emitting diode (micro LED) display screen, etc.

[0182] It is understandable that the optical display device may also include other possible structures, and the present application does not limit this. For example, referring to Figure 14, a circuit diagram of an optical display device provided by the present application. The circuit in the optical display device mainly includes a host processor (host CPU) 1101, an external memory interface 1102, an internal memory 1103, an audio module 1104, a video module 1105, a power module 1106, a wireless communication module 1107, an I / O interface 1108, a video interface 1109, a display circuit 1110, a modulator 1111 and a light source 1112, etc. Wherein, the main processor 1101 and its peripheral components, such as the external memory interface 1102, the internal memory 1103, the audio module 1104, the video module 1105, the power module 1106, the wireless communication module 1107, the I / O interface 1108, the video interface 1109 and the display circuit 1110, can be connected by a bus. The main processor 1101 is also referred to as a front-end processor.

[0183] In addition, the circuit diagrams shown in the embodiments of the present application do not constitute specific limitations on the optical display device. In other embodiments of the present application, the optical display device may include more or fewer components than shown, or may combine or separate certain components, or have different component arrangements. The components shown in the diagrams may be implemented in hardware, software, or a combination of software and hardware.

[0184] The main processor 1101 includes one or more processing units, such as an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU). Different processing units can be independent devices or integrated into one or more processors.

[0185] The external memory interface 1102 can be used to connect an external memory card, such as a Micro SD card, to expand the storage capacity of the optical display device. The external memory card communicates with the main processor 1101 through the external memory interface 1102 to implement data storage function.

[0186] The internal memory 1103 can be used to store computer executable program code, and the executable program code includes instructions. The internal memory 1103 may include a program storage area and a data storage area. Among them, the program storage area can store an operating system, an application required for at least one function (such as a call function, a time setting function, etc.), etc. The data storage area can store data created during the use of the optical display device (such as a phone book, world time, etc.). In addition, the internal memory 1103 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, a universal flash memory (UFS), etc. The main processor 1101 executes various functional applications and data processing of the optical display device by running the instructions stored in the internal memory 1103 and / or the instructions stored in the memory provided in the main processor 1101.

[0187] In some embodiments, the optical display device may further include a plurality of input / output (I / O) interfaces 1108 connected to the main processor 1101, such as an inter-integrated circuit (I2C) interface, an inter-integrated circuit sound (I2S) interface, a pulse code modulation (PCM) interface, a universal asynchronous receiver / transmitter (UART) interface, a mobile industry processor interface (MIPI), a general-purpose input / output (GPIO) interface, a subscriber identity module (SIM) interface, and / or a universal serial bus (USB) interface. The I / O interfaces 1108 may be connected to audio modules such as a mouse, a touchpad, a keyboard, a camera, a speaker, a microphone, and the like, and may also be connected to physical buttons on the optical display device (e.g., a volume button, a brightness adjustment button, a power button, etc.).

[0188] The audio module 1104 is used to convert digital audio information into analog audio signals for output, and also to convert analog audio input into digital audio signals. The audio module 1104 can also be used to encode and decode audio signals, for example, for playback or recording. In some embodiments, the audio module 1104 can be provided within the processor 1101, or some functional modules of the audio module 1104 can be provided within the processor 1101. The optical display device can implement audio functions such as music playback and phone calls through the audio module 1104 and an application processor.

[0189] The video interface 1109 can receive external audio and video signals, which can specifically be a high-definition multimedia interface (HDMI), a digital visual interface (DVI), a video graphics array (VGA), a display port (DP), etc. The video interface 1109 can also output video. When the optical display device is used as a head-up display, the video interface 1109 can receive speed signals and power signals input from peripheral devices, and can also receive external AR video signals. When the optical display device is used as a projector, the video interface 1109 can receive video signals input from an external computer or terminal device.

[0190] The video module 1105 can decode the video input from the video interface 1109, for example, by performing H.264 decoding. The video module can also encode the video captured by the optical display device, for example, by performing H.264 encoding on the video captured by an external camera. Furthermore, the main processor 1101 can also decode the video input from the video interface 1109 and output the decoded image signal to the display circuit 1110.

[0191] The display circuit 1110 and modulator 1111 are used to display the corresponding image. Here, the projection lens and display screen in any of the above-described embodiments may be located in the display circuit 1110, and the prism structure and display chip in any of the above-described embodiments may be located in the modulator 1111. In this embodiment, the video interface 1109 receives an external video source signal, which the video module 1105 decodes and / or digitizes, and then outputs one or more image signals to the display circuit 1110. The display circuit 1110 drives the modulator 1111 based on the input image signal to project the incident light beam into an image, thereby outputting the projected image light. Furthermore, the main processor 1101 may also output one or more image signals to the display circuit 1110.

[0192] The power module 1106 is used to provide power to the main processor 1101 and the light source 1112 based on input power (e.g., direct current). The power module 1106 may include a rechargeable battery, which can provide power to the main processor 1101 and the light source 1112. The light emitted by the light source 1112 can be transmitted to the modulator (or image source) 1111 for imaging, thereby forming image light. Here, the light source 1112 can be the light source module in any of the above-mentioned embodiments.

[0193] The wireless communication module 1107 enables the optical display device to communicate wirelessly with the outside world. It can provide wireless local area networks (WLAN) (such as wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite system (GNSS), frequency modulation (FM), near field communication (NFC), infrared technology (IR) and other wireless communication solutions. The wireless communication module 1107 can be one or more devices that integrate at least one communication processing module. The wireless communication module 1107 receives electromagnetic waves via an antenna, frequency modulates and filters the electromagnetic wave signals, and sends the processed signals to the main processor 1101. The wireless communication module 1107 can also receive the signal to be sent from the main processor 1101, frequency modulate and amplify it, and convert it into electromagnetic waves for radiation through the antenna.

[0194] In addition, in addition to being input through the video interface 1109, the video data decoded by the video module 1105 can also be received wirelessly through the wireless communication module 1107 or read from an external memory. For example, the optical display device can receive video data from a terminal device or an in-vehicle entertainment system through the wireless local area network in the vehicle, and the optical display device can also read audio and video data stored in an external memory.

[0195] Exemplarily, the optical display device may include but is not limited to a HUD, a projector, an AR device, a VR device, or an MR device, among which the AR device may include but is not limited to AR glasses or an AR helmet, the VR device may include but is not limited to VR glasses or a VR helmet, and the MR device may include but is not limited to MR glasses or an MR helmet.

[0196] Based on the structure and functional principles of the optical display device described above, the present application may also provide a vehicle. This vehicle may include the optical display device of any of the above embodiments. Please refer to Figure 15 for a schematic diagram of a possible functional framework of a vehicle provided by the present application. Optionally, one or more of the above components may be installed or associated separately from the vehicle 100. For example, the memory 163 may be partially or completely separate from the vehicle 100. The above components may be communicatively coupled together via wired and / or wireless means.

[0197] It should be noted that the vehicle functional framework shown in FIG15 is merely an example. In other examples, the vehicle 100 may include more, fewer, or different systems, and each system may include more, fewer, or different components. Furthermore, the systems and components shown may be combined or divided in any manner, and this application does not impose any specific limitations thereon.

[0198] The above-mentioned vehicle 100 can be a car, truck, motorcycle, bus, boat, airplane, helicopter, lawn mower, recreational vehicle, amusement park vehicle, construction equipment, tram, golf cart, train, and cart, etc., and this application does not limit this.

[0199] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple. In the text description of this application, the character " / " generally indicates that the related objects before and after are in an "or" relationship. In the formula of this application, the character " / " indicates that the related objects before and after are in a "divided" relationship. In addition, in this application, the word "exemplarily" is used to indicate an example, illustration or description. Any embodiment or design described as an "example" in this application should not be interpreted as being more preferred or advantageous than other embodiments or designs. Alternatively, it can be understood that the use of the word "example" is intended to present concepts in a specific way and does not limit this application.

[0200] It will be appreciated that the various numerical numbers involved in this application are merely for the purpose of describing the distinctions made, and are not intended to limit the scope of the embodiments of the present application. The size of the sequence numbers of the above-mentioned processes does not imply the order of execution, and the order of execution of each process should be determined by its function and inherent logic. Terms such as "first", "second", and similar expressions are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, comprising a series of steps or units. Methods, systems, products, or devices are not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, methods, products, or devices.

Claims

1. A prism structure, characterized in that: include: A first prism, a quadrangular prism, and a second prism; The first triangular prism includes three side surfaces that are quadrilateral and two main surfaces that are triangular, the quadrangular prism includes four side surfaces that are quadrilateral and two main surfaces that are quadrilateral, and the second triangular prism includes three side surfaces that are quadrilateral and two main surfaces that are triangular; The second side surface of the first triangular prism is attached to the first side surface of the quadrangular prism, the second side surface of the quadrangular prism is attached to the first side surface of the second triangular prism, and the fourth side surface of the quadrangular prism is painted black; Among them, the first side surface of the prism and the second side surface of the prism are two opposite surfaces, and the fourth side surface of the prism is a surface connecting the first side surface of the prism and the second side surface of the prism and opposite to the third side surface of the second prism.

2. An optical system, characterized in that: A prism structure is provided, wherein a display chip is placed in a first direction of the prism structure, a projection lens is placed in a second direction of the prism structure, the prism structure comprises a first layer, a second layer and a third layer stacked in sequence along the second direction, and a fourth side surface of the second layer in a direction opposite to the first direction is painted black; The first layer is used to guide the illumination light beam into the second layer, or to guide the non-projection light beam out; The second layer is used to guide the illumination light beam into the display chip, reflect the projection light beam reflected from the display chip to the third layer, and guide the non-projection light beam reflected from the display chip to the fourth side surface, or guide it to the first layer; The third layer is used to guide the projection light beam into the projection lens.

3. The optical system according to claim 2, characterized in that The third layer is further used to reflect the non-projection light beam reflected from the display chip to the fourth side surface.

4. The optical system according to claim 2 or 3, characterized in that The projection light beam includes a light beam reflected by the display chip at a first deflection angle; The non-projection light beam includes a light beam reflected by the display chip at a second deflection angle and a light beam reflected by the display chip at a third deflection angle; Wherein, different deflection angles correspond to different states of the display chip.

5. The optical system according to any one of claims 2 to 4, characterized in that The prism structure is the prism structure as described in claim 1, the first layer is the first triangular prism, the second layer is a quadrangular prism, the third layer is the second triangular prism, the display chip is placed on the outside of the third side surface of the quadrangular prism, and the projection lens is placed on the outside of the second side surface of the second triangular prism.

6. The optical system according to claim 5, characterized in that The included angle between the first side surface of the prism and the third side surface of the prism is 45°.

7. The optical system according to claim 5 or 6, characterized in that: The second side surface of the second prism is perpendicular to the third side surface of the second prism.

8. The optical system according to any one of claims 5 to 7, characterized in that The third side surface of the quadrangular prism and the third side surface of the second triangular prism are located on the same plane, and the display chip is located below the plane.

9. The optical system according to any one of claims 5 to 8, characterized in that The fourth side surface of the quadrangular prism is parallel to the third side surface of the quadrangular prism, and an area of ​​the fourth side surface of the quadrangular prism is smaller than an area of ​​the third side surface of the quadrangular prism.

10. The optical system according to any one of claims 5 to 9, characterized in that Part of the non-projection light beam reflected by the display chip is reflected once or multiple times in the prism, part of it is guided to the fourth side surface of the prism, and part of it is reflected to the first prism and then guided out of the prism structure.

11. The optical system according to claim 10, wherein: Another part of the non-projection light beam reflected by the display chip is refracted to the fourth side surface of the prism through the third side surface of the prism.

12. The optical system according to claim 10 or 11, characterized in that Another portion of the non-projection light beam reflected by the display chip passes through the second side surface of the second triangular prism and is reflected to the fourth side surface of the quadrangular prism.

13. The optical system according to any one of claims 5 to 12, characterized in that The projection light beam reflected by the display chip is reflected to the second side surface of the prism through the first side surface of the prism, refracted to the second side surface of the second prism on the second side surface of the prism, and guided to the projection lens on the second side surface of the second prism.

14. The optical system according to claim 13, wherein: The non-projection light beam reflected by the display chip is reflected to the second side surface of the prism through the first side surface of the prism, and is reflected to the fourth side surface of the prism on the second side surface of the prism.

15. The optical system according to claim 14, wherein: An incident angle of the projection light beam on the second side surface of the quadrangular prism is smaller than an incident angle of the non-projection light beam on the second side surface of the quadrangular prism.

16. The optical system according to claim 13 or 14, characterized in that The selection of the inclination angle of the second side surface of the prism and the refractive index of the material of the prism is used to achieve that the projection light beam is transmitted on the second side surface of the prism and the non-projection light beam is reflected on the second side surface of the prism.

17. The optical system according to any one of claims 13 to 16, characterized in that The incident angle of the projection light with the largest incident angle in the projection light beam on the second side surface of the prism is less than the critical angle of total reflection corresponding to the second side surface of the prism, and the incident angle of the projection light with the smallest incident angle in the non-projection light beam on the second side surface of the prism is greater than or equal to the critical angle of total reflection corresponding to the second side surface of the prism.

18. An optical system according to any one of claims 5 to 17, characterized in that The refractive index of the material of the quadrangular prism is the same as the refractive index of the material of the second triangular prism.

19. The optical system according to any one of claims 5 to 18, characterized in that The non-effective light path portion of one or more outer surfaces of the prism structure except the fourth side surface of the four-prism is painted black.

20. The optical system according to any one of claims 5 to 19, characterized in that The second prism is fixedly arranged or integrated with the lens of the projection lens that is closest to the second prism.

21. The optical system according to claim 20, characterized in that When the second prism and the lens are fixedly arranged, a side of the lens relative to the second prism is arranged as a plane.

22. An optical display device, characterized in that: A device comprising a display chip, a projection lens and an optical system as claimed in any one of claims 2 to 21; The display chip is used to reflect the illumination light beam introduced from the second layer at different deflection angles; The projection lens is used to project the magnified image according to the projection light beam introduced by the third layer.

23. The optical display device according to claim 22, characterized in that: It also includes a light source; The light source is used to emit an illumination light beam to the third layer.

24. The optical display device according to claim 22 or 23, characterized in that: Also includes display screen; The display screen is used to display the magnified image from the projection lens.

25. A terminal device, characterized in that: An optical display device comprising the optical display device as claimed in any one of claims 22 to 24.

Images