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

Abstract

A prism structure, an optical system, an optical display device and a terminal device are used for improving the contrast ratio of projection lens imaging. The optical system comprises a prism structure, the prism structure comprises a first layer, a second layer and a third layer which are sequentially stacked, the fourth side face of the second layer is blackened, and the first layer is used for guiding illumination light beams into the second layer or guiding out non-projection light beams; the second layer is used for guiding an illumination light beam into the display chip, reflecting a projection light beam reflected by the display chip to the third layer, and guiding a non-projection light beam reflected by the display chip to the third side surface or guiding the non-projection light beam to the first layer; and the third layer is used for guiding the projection beam into the projection lens. The non-projection light beam is guided to the blackened prism surface to be absorbed or guided out of the prism structure, so that the non-projection light beam in the optical system can be effectively inhibited, the probability that the non-projection light beam enters the projection lens to participate in imaging is reduced, and the contrast ratio of projection is improved.

Description

Technical Field

[0001] 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 equipment. Background Art

[0002] In recent years, with the development of projection display technology, people's demand for projection display effects has become increasingly higher. Among many 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 field of projection display.

[0003] In order to achieve a compact structure, DLP display devices usually use total internal reflection (TIR) ​​prisms or reverse total internal reflection (RTIR) prisms to couple the illumination light. However, in the existing prism solution, the non-projection light beams generated by the DLP display device will also enter the projection lens to participate in the projection. After one or more reflections or refractions in the projection lens, these non-projection light beams will form stray light on the final image plane, affecting the contrast of the final image.

[0004] In summary, how to improve the contrast of projection lens imaging is a technical problem that urgently needs to be solved. Summary of the invention

[0005] The present application provides a prism structure, an optical system, an optical display device and a terminal device, which are used to improve the contrast of projection lens imaging.

[0006] In a first aspect, the present application provides a prism structure, including a first triangular prism, a quadrangular prism, and a second triangular prism, wherein the first triangular prism includes three sides presenting as quadrilaterals and two main faces presenting as triangles, the quadrangular prism includes four sides presenting as quadrilaterals and two main faces presenting as quadrilaterals, the second triangular prism includes three sides presenting as quadrilaterals and two main faces presenting as triangles, 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.

[0007] In the above scheme, the fourth side of the prism is painted black, so that the non-projection light beam can be guided to the fourth side painted black for absorption, effectively suppressing the non-projection light beam in the prism structure, allowing a relatively pure projection light beam to enter the projection lens for imaging, thereby improving the projection contrast of the projection lens. In addition, the prism structure can suppress the non-projection light by simply painting the prism surface black, without the need for additional display chips, additional angle selective film coating, and no need to carefully design the angle and position constraints of the prism structure in order to derive the non-projection light beam, thereby reducing the volume, cost and weight of the prism structure.

[0008] In a second aspect, the present application provides an optical system, including a prism structure, 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, and the prism structure includes a first layer, a second layer, and a third layer stacked in sequence along the second direction, and the fourth side surface of the second layer in the opposite direction of the first direction is painted black. When the optical system is working, the first layer is used to guide the illumination beam into the second layer, or to guide the non-projection beam out; the second layer is used to guide the illumination beam into the display chip, and reflect the projection beam reflected from the display chip to the third layer, guide the non-projection 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 beam into the projection lens.

[0009] 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.

[0010] In a possible design, the third layer is also used to reflect the non-projection light beam reflected from the display chip to the fourth side. In this way, even if the non-projection light beam reflected by the display chip is not completely reflected back to the second layer, but a part of it is reflected to the third layer, it can be reflected by the third layer to the blackened prism surface in the second layer and absorbed, and will not enter the subsequent projection lens. In this way, the third layer can be considered as a leak-proof layer of the second layer, which is used to suppress the non-projection light beam that fails to be reflected to the second layer, further eliminate the non-projection light beam in the optical system, and reduce the influence of stray light in the optical system.

[0011] In a possible design, the projection light beam includes a light beam reflected by the display chip at a first deflection angle, and 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. Optionally, the first deflection angle may be a deflection angle corresponding to the "on" state, the second deflection angle may be a deflection angle corresponding to the "flat" state, and the third deflection angle may be a deflection angle corresponding to the "off" state. In other words, the projection light beam may include an "on" state light beam, and the non-projection light beam may include an "off" state light beam and a "flat" state light beam. In this way, by suppressing both the "off" state light beam and the "flat" state light beam, the "off" state light beam and the "flat" state light beam, which are two invalid light beams, can avoid as much as possible the "off" state light beam and the "flat" state light beam from entering the projection lens to form stray light, which helps to improve the contrast of the projection imaging.

[0012] It should be noted that the prism structure in the second aspect may be the prism structure in the first aspect, or other prism structures, 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, etc. It should be understood that any prism structure that can absorb non-projection light beams by blackening the prism surface is within the protection scope of this application.

[0013] For ease of introduction, the prism structure in the second aspect is taken as an example as the prism structure in the first aspect mentioned above. In this case, the first layer is the first prism, the second layer is the quadrangular prism, and the third layer is the second 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 prism.

[0014] In a possible design of the first aspect or the second aspect, the angle between the first side surface of the prism and the third side surface of the prism is 45°. Thus, the 45° angle can mirror the display chip located in the first direction of the prism structure to the opposite direction of the second direction of the prism structure, so that the mirrored display chip and the projection lens located in the second direction of the prism structure can be on the same axis, and the projection light beam reflected by the display chip is equivalent to being transmitted to the projection lens in a straight line, which can reduce the probability of deformation or dislocation of the projection light beam and improve the imaging quality of the projection lens.

[0015] In a further possible design, the second side surface of the second prism is perpendicular to the third side surface of the second prism. In this way, after the projection light beam reflected by the quadrangular prism enters the second prism in a straight line direction, it is emitted from the second side surface of the second prism. The emission direction can be kept parallel to the third side surface of the quadrangular prism under the effect of the above-mentioned 45° angle. Furthermore, since the second side surface of the second prism is perpendicular to its third side surface, the projection light beam emitted from the second side surface of the second prism vertically enters the third side surface, and then can be emitted vertically from the third side surface, so that the direction of the projection light beam can be ensured not to change.

[0016] In a possible design of the first aspect or the second aspect, the third side surface of the quadrangular prism and the third side surface of the second prism are located in the same plane, and the display chip can be located below the plane. In this way, the third side surface of the quadrangular prism and the third side surface of the second prism constitute the bottom surface of the prism structure, and setting it in a flat shape is not only more beautiful, but also allows the light beam reflected by the display chip to refract into the quadrangular prism and the second prism at the same vertical position, which is convenient for realizing the design of the light transmission path.

[0017] In a further possible design, the fourth side surface of the prism is parallel to the third side surface of the prism, and the area of ​​the fourth side surface of the prism is smaller than the area of ​​the third side surface of the prism. In this way, the third side surface of the prism serves as the bottom surface of the prism structure, and the fourth side surface of the prism serves as the top surface of the prism structure. The bottom surface has a larger area, which helps to make the prism structure more stable.

[0018] In a possible design of the second aspect, part of the non-projection light beam reflected by the display chip is reflected once or multiple times in the prism, part of which is guided to the fourth side surface of the prism, and part of which is reflected to the first prism and then guided out of the prism structure. In this way, the non-projection light beam reflected in the prism can be guided to the blackened surface for absorption, or guided out of the prism structure.

[0019] In a possible design of the second aspect, another portion of the non-projection light beam reflected by the display chip is refracted to the fourth side of the prism through the third side 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.

[0020] In a possible design of the second aspect, another portion of the non-projection light beam reflected by the display chip is reflected to the fourth side surface of the quadrangular prism through the second side surface of the second prism. In this way, the non-projection light beam reflected to the second prism can be guided to the blackened surface of the quadrangular prism for absorption.

[0021] In a possible design of the second aspect, 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, transmitted from the second side surface of the prism to the second side surface of the second prism, and guided to the projection lens from the second side surface of the second prism. In this way, the projection light beam reflected into the prism can be directly reflected by the prism into the second prism, and then directly refracted into the projection lens by the second prism. This transmission method can guide the projection light beam to the projection lens through a shorter optical path, thereby reducing energy waste of the projection light beam.

[0022] In a 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 is reflected from the second 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 be guided to the blackened surface for absorption through two reflections in the prism, so that the transmission path of the non-projection light beam from entering the prism to being eliminated is shorter, which can reduce the probability of stray light introduced by multiple reflections or refractions of the non-projection light beam in the prism.

[0023] In a possible design of the second aspect, the incident angle of the projection beam on the second side of the prism is smaller than the incident angle of the non-projection beam on the second side of the prism. The smaller the incident angle of the projection beam on the second side of the prism, the more likely it is to be smaller than the critical angle of total reflection corresponding to the second side of the prism, and the easier it is to achieve refraction of the projection beam on the second side of the prism. The larger the incident angle of the non-projection beam on the second side of the prism, the more likely it is to be larger than the critical angle of total reflection corresponding to the second side of the prism, and the easier it is to achieve total reflection of the non-projection beam on the second side of the prism. In other words, by making the incident angle of the projection beam on the second side of the prism smaller than the incident angle of the non-projection beam on the second side of the prism, it helps to use the critical angle of total reflection of the second side of the prism to separate the projection beam and the non-projection beam.

[0024] In a possible design of the second aspect, 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 the refraction of the projection beam on the second side surface of the prism and the reflection of the non-projection beam on the second side surface of the prism. In this way, the selected inclination angle of the second side surface of the prism and the refractive index of the material of the prism can meet the requirements of ensuring the transmission of the projection beam and the reflection of the non-projection beam, thereby achieving the function of suppressing the non-projection beam and transmitting the projection beam.

[0025] In a possible design of the second aspect, 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. In this way, there is no overlap between the incident angle of the projection light beam on the second side surface of the prism and the incident angle of the non-projection light beam on the second side surface of the prism, so that there is a certain interval between the projection light beam and the non-projection light beam, which provides support for separating the two state light beams by reflection or refraction in the prism structure.

[0026] In a possible design of the second aspect, the refractive index of the quadrangular prism is the same as the refractive index of the second prism. Thus, the second side surface of the bonded quadrangular prism and the first side surface of the second prism have the same effect as transparent glass for the transmission of the projection light beam, and can be used to keep the main transmission direction of the projection light beam unchanged.

[0027] In a possible design of the second aspect, the non-effective light path portion of one or more outer surfaces of the prism structure except the fourth side surface of the quadrangular prism is painted black. In this way, by painting the surfaces of the entire prism structure through which no effective light beam passes, the non-projection light beam projected onto these surfaces can be directly absorbed by these blackened surfaces, thereby suppressing the reflection or refraction of the non-projection light beam in the prism structure as much as possible, and reducing the probability of generating stray light in the projection lens.

[0028] In a possible design of the second aspect, the second prism is fixedly arranged or integrated with the lens closest to the second prism in the projection lens. In this way, not only the volume of the optical system can be saved, but also the back focus distance of the optical system can be reduced, thereby reducing the difficulty of designing the back focus system.

[0029] In a further possible design, when the second prism and the lens are fixedly arranged, the lens is arranged to be a plane on one side relative to the second prism. In this way, the plane of the last lens can be directly attached to the second prism P3 for fixing, and the plane shape can make it easier to fix.

[0030] 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, the display chip being used to reflect an illumination light beam introduced from the second layer at different deflection angles, and the projection lens being used to project an enlarged image according to the projection light beam introduced from the third layer.

[0031] 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, etc.

[0032] 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 higher, more lenses may be configured in the projection lens. When the requirements for projection clarity and projection field of view are lower, fewer lenses may be configured in the projection lens.

[0033] In a possible design, the optical display device further includes a light source, which is used to emit an illumination light beam to the third layer.

[0034] 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).

[0035] 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.

[0036] In a fourth aspect, the present application provides a terminal device, comprising an optical display device as described in any one of the designs of the third aspect above.

[0037] In one possible design, the terminal device may be a projector, a head-up display (HUD) or a near eye display (NED) device.

[0038] The beneficial effects of any design 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

[0039] Figure 1 A schematic diagram of a total reflection optical path provided by the present application is exemplarily shown;

[0040] Figure 2a A schematic diagram showing an application scenario of a projector to which the present application is applicable;

[0041] Figure 2b A schematic diagram showing an application scenario of a vehicle-mounted projector provided by the present application is exemplified;

[0042] Figure 2c A schematic diagram showing an application scenario of a head-up display device provided by the present application is exemplified;

[0043] Figure 2d A schematic diagram showing an application scenario of an augmented reality device provided by the present application is exemplified;

[0044] Figure 3a A schematic diagram showing the structure of an optical display device provided by the present application is exemplified;

[0045] Figure 3b A schematic diagram showing stray light distribution in an optical display device is exemplified;

[0046] Figure 3c A schematic diagram showing a solution of a prism structure provided by the industry is exemplified;

[0047] Figure 3d A schematic diagram showing another solution of a prism structure provided by the industry;

[0048] Figure 3e A schematic diagram showing another solution of a prism structure provided by the industry is exemplified;

[0049] Figure 4 A schematic structural diagram of a prism structure provided by the present application is exemplified;

[0050] Figure 5 A schematic diagram showing a volume comparison between the prism structure provided by the present application and the prism structure provided by the industry;

[0051] Figure 6 A schematic diagram of an optical path of an optical system provided by the present application is exemplified;

[0052] Figure 7a A schematic diagram showing a blackening method of a prism structure provided by the present application is exemplified;

[0053] Figure 7b A schematic diagram showing another blackening method of a prism structure provided by the present application;

[0054] Figure 8a A schematic diagram showing a deflection state of a display chip provided by the present application is exemplified;

[0055] Figure 8b A schematic diagram of reflected light of a display chip provided by the present application is exemplarily shown;

[0056] Fig. 9 A schematic diagram of a light beam transmission path provided by the present application is exemplarily shown;

[0057] Fig.10 A schematic diagram exemplarily showing a method provided by the present application in which the same light irradiates a second side surface at different inclination angles;

[0058] Fig.11 A schematic diagram showing the structure of a projection lens provided by the present application is exemplified;

[0059] Fig.12 A schematic diagram showing an exemplary method of fixing a lens and a prism structure provided by the present application;

[0060] Fig.13 A schematic diagram showing an exemplary method for calculating a back focus distance provided by the present application;

[0061] Fig.14 A circuit diagram of an optical display device provided by the present application is exemplarily shown;

[0062] Fig.15 A functional framework diagram of a vehicle provided by the present application is exemplified. DETAILED DESCRIPTION

[0063] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0064] Below, some terms in this application are explained. It should be noted that these explanations are for the convenience of understanding by those skilled in the art and do not constitute a limitation on the scope of protection claimed in this application.

[0065] 1. Projection beam and non-projection beam

[0066] The projection beam can be understood as a beam that needs to enter the projection lens for projection. Among the beams reflected by the display chip, a part of the beam is required for projection and can be shot into the projection lens for projection imaging. This part of the beam is the projection beam. Corresponding to the projection beam, the non-projection beam can be understood as a 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 projection imaging, so it is necessary to avoid it from entering the projection lens.

[0067] 2. Total Internal Reflection

[0068] Total internal reflection, also known as total internal reflection, is an optical phenomenon. When light is emitted from a denser medium to a less dense medium, if the incident angle is greater than the critical angle of total reflection, the refracted light will disappear completely, and all the incident light will be reflected without entering the less dense medium. This phenomenon is called total internal reflection. For example, see Figure 1, at the interface between the optically denser medium and the optically sparser medium, the light from the optically denser medium whose incident angle is less than the critical angle of total reflection θ1 (as shown by the dotted line in the figure) can be refracted into the optically sparser medium, while the light from the optically denser medium whose incident angle is 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 optically denser medium. Among them, the critical angle of total reflection θ1 is related to the refractive index n1 of the optically denser medium and the refractive index n2 of the optically sparser medium, which can be calculated by the following formula (1.1):

[0069]

[0070] 3. Back focus distance

[0071] Back focal distance (BFD), also known as 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 in the projection lens.

[0072] The foregoing text introduces some of the terms involved in this application. The following text introduces possible application scenarios of this application.

[0073] In a possible application scenario, the prism structure in this application can be integrated into a projector, see Figure 2a , 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-throw projectors, short-throw projectors, and ultra-short-throw projectors. Long-throw projectors are suitable for use in bedrooms and living rooms, and are generally placed on bedside tables or next to sofas. Short-throw projectors are mainly suitable for educational or business projection, such as cinema projection, office projection, etc. Ultra-short-throw projectors can be set up at a short distance, such as the projector of a laser TV, which basically only needs to be placed on a TV cabinet.

[0074] In some special scenarios, projectors can also be installed on vehicles. For example, those installed on vehicles are called vehicle-mounted projectors, those installed on airplanes are called airborne projectors, and those installed on ships are called ship-mounted projectors. For example, please refer to Figure 2b The vehicle projector can be installed anywhere in the vehicle cabin, such as above the headrest, behind the seat, in the armrest box or in front of the rear glass. In some scenarios, the vehicle projector can also have a steering function, which can be turned to different directions to achieve projection on the cabin curtain, skylight glass, side window glass or front and rear windshields.

[0075] In another possible application scenario, the prism structure in the present application can be integrated into a head-up display (HUD), see Figure 2c . Figure 2c Take the installation of HUD in a vehicle as an example. HUD can project the formed image (called HUD virtual image) into the front field of view of the driver (also called eye box), and integrate it with the real road information to enhance the driver's perception of the actual driving environment. For example, HUD can superimpose the HUD virtual image carrying navigation information and / or instrument information (such as driving speed, mileage, speed, temperature, fuel level, light status, etc.) on the real environment outside the car, so that the driver can obtain the visual effect of augmented reality. It can be specifically applied to scenes such as augmented reality (AR) navigation, adaptive cruise, lane departure warning, etc. Among them, HUD includes but is not limited to windshield (windshield, W)-HUD, augmented reality head up display (augmented reality head up display, AR-HUD), etc.

[0076] In another possible application scenario, the prism structure in 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 can include but are not limited to AR glasses or AR helmets, VR devices can include but are not limited to VR glasses or VR helmets, and MR devices can include but are not limited to MR glasses or MR helmets. Please refer to Figure 2d Taking AR glasses as an example, users can wear AR glasses to play games, watch videos, participate in virtual meetings, or do video shopping.

[0077] 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 given above, such as in-vehicle displays, and in smart car lights.

[0078] In the present application, the prism structure may be integrated into an optical display device, which may be, for example, the aforementioned projector, HUD or NED device. Figure 3a, exemplarily showing a schematic diagram of the structure of an optical display device. The optical display device 300 may include a light source 310, an optical system 320, a display chip 330 and a projection lens 340, and the prism structure may be integrated in the optical system 320. Optionally, the optical display device 300 may also include a display screen 350. The light source 310 is located on the left side of the optical system 320 in the figure, the display chip 330 is located below the optical system 320 in the figure, the projection lens 340 is located on the right side of the optical system 320 in the figure, and the display screen 350 is located on the right side of the projection lens 340 in the figure. When the optical display device 300 is working, the light source 310 may emit illumination light, which is refracted by the prism structure in the optical system 320 and irradiated on the display chip 330, and then reflected by the display chip 330 back to the optical system 320, and exported to the projection lens 340 through the prism structure in the optical system 320, and then the image corresponding to the incident light is magnified through the projection lens 340, and finally imaged on the display screen 350.

[0079] It is understandable that the light beam reflected by the display chip 330 may generally include a projection light beam and a non-projection light beam. The projection light beam is the light beam required for projection, and the non-projection light beam is the light beam not required for projection, and should be prevented from entering the projection lens 340. However, as described in the background technology, the existing prism solution will also guide the non-projection light beam to the projection lens 340. After one or more reflections or refractions in the projection lens 340, these non-projection light beams will most likely form stray light that is emitted in all directions, such as Figure 3b These stray lights will obviously interfere with the imaging brightness of the projection light beam by the projection lens 340, thereby reducing the projection contrast.

[0080] 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:

[0081] For one solution, see Figure 3c , by setting up two display chips 1 and 2, the brightness of each pixel on the display chip 1 can obtain a square relationship on the original contrast after passing through a display chip 2. For example, assuming that the bright pixel and the dark pixel can obtain a contrast ratio of 10:1 after being processed by the display chip 1, then after being processed by the second display chip 2, 10:1 can be further superimposed on the 10:1 contrast ratio, so that the contrast ratio is reduced to 100:1. Although this solution can effectively increase the brightness difference between different pixels, when adding display chips, the corresponding projection light path must also be added, which will complicate the overall structure of the projection display device and increase the volume. In addition, the display chip is expensive, and adding a display chip will greatly increase the cost, which does not meet the design concept of miniaturization and low cost.

[0082] For another solution, see Figure 3d , taking advantage of the different exit angles of the projection beam and the non-projection beam reflected by the display chip, by coating an angle selective film on the surface of prism 4 relative to prism 3, and configuring the angle selective film to have a selection angle value greater than or equal to the incident angle of the projection beam projected on the surface and less than the incident angle of the non-projection beam projected on the surface, so that the projection beam with an incident angle less than or equal to the selected angle value can pass through the angle selective film to enter the projection lens, while the non-projection beam with an incident angle greater than the selected angle value cannot pass through the angle selective film and is reflected back to prism 3. Although this method can filter the non-projection beam by utilizing the angle selective characteristics of the angle selective film, it is difficult to achieve an ideal coating effect of the angle selective film at this stage, 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 the projection contrast. In addition, after the non-projection light beam is reflected back to the prism 3, it may be reflected or refracted once or multiple times in the prism 3, prism 2 and prism 1, and then enter the surface of the prism 4 relative to the prism 3 again. If the incident angle at this time is less than or equal to the selected angle value, the non-projection light beam will pass through the angle selective film layer and enter the subsequent projection lens, becoming stray light. It can be seen that this solution can only prevent part of the non-projection light beam from entering the projection lens, and adding an angle selective film layer will also increase the corresponding cost, and it cannot meet the low-cost design concept.

[0083] For another solution, see Figure 3e , prism 1, prism 2 and prism 3 are spliced ​​together, and through precise design, a special spatial position and angle constraint is formed between the three prisms. Through the special spatial position and angle constraint, the non-projection light beam (as shown in the figure with black solid line) is derived from one or more prisms among prism 1, prism 2 and prism 3, and the projection light beam (as shown in the figure with light solid line) is totally reflected on the surface S1 of prism 2 to prism 3, and then derived from prism 3 to the projection lens. Although this solution can derive the non-projection light beam from the prism structure, its realization is completely dependent on the spatial position and angle design of the three prisms. The three prisms need to meet many beam restriction conditions, resulting in the entire prism structure requiring a larger space volume to be realized, which greatly increases the volume and weight of the whole machine.

[0084] 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.

[0085] Based on the above content, the following Figure 4 To Attachment Fig.12 , the prism scheme proposed in this application is specifically explained.

[0086] In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and / or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.

[0087] In addition, in this application, "angle" does not mean an absolute angle, and a certain engineering error can be allowed. "Uniform" does not mean absolute uniformity, and a certain engineering error can be allowed. "Vertical" does not mean absolute verticality, and a certain engineering error can be allowed.

[0088] like Figure 4 The figure is a schematic diagram of a prism structure provided by the present application. Figure 4 (A) shows a three-dimensional diagram of a prism structure. Figure 4 (B) shows the front view of the prism structure. Figure 4 (C) shows the left side view of the prism structure. Figure 4 Middle(A) to Figure 4 In (C), the prism structure includes a first prism P1, a quadrangular prism P2 and a second prism P3, and the first prism P1, the quadrangular prism P2 and the second prism P3 are spliced ​​into a prism. Figure 4 Taking the viewing angle shown in (A) as an example, the side on the left side of any prism or quadrangular prism in the figure is called the first side face, the side on the right side in the figure is called the second side face, the side at the bottom in the figure is called the third side face, the side in front of the figure is called the first principal face, the side in the rear of the figure is called the second principal face, and the side above the quadrangular prism in the figure is called the fourth side face. Then: the first prism P1 includes three side faces that are quadrilaterals and two principal faces that are triangular, the quadrangular prism P2 includes four side faces that are quadrilaterals and two principal faces that are quadrilaterals, the second prism P3 includes three side faces that are quadrilaterals and two principal faces that are triangular, and the second side face of the first prism P1 is in contact with the first side face of the quadrangular prism P2, the second side face of the quadrangular prism P2 is in contact with the first side face of the second prism P3, and the fourth side face of the quadrangular prism P2 is painted black.

[0089] Optionally, in a prism structure, any two abutting sides may have the same shape and size. For example, see Figure 4 In (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.

[0090] Further optionally, the bonding 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 bonded together, 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 are correspondingly bonded together, and the second side surface of the quadrangular prism P2 and the first side surface of the second prism P3 are bonded together, 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 are correspondingly bonded together. In addition to the four corners that are bonded 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.

[0091] It is understandable that the fourth side surface of the prism P2 is painted black, which means that the outer surface of the prism P2 is painted black. The blackening operation can be performed before splicing the first prism P1, the prism P2 and the second prism P3, or after splicing the first prism P1, the prism P2 and the second prism P3 together, and there is no specific limitation.

[0092] It can be understood that any black material can be selected for blackening, such as ink, water-based paint, paint or ink.

[0093] use Figure 4 The prism structure shown in the figure, by coating the fourth side of the prism P2 black, can guide the non-projection light beam to the blackened fourth side for absorption, so that a relatively pure projection light beam enters the projection lens for imaging. It can be seen that the prism structure can eliminate the non-projection light by only coating the prism surface black, and does not need the above-mentioned Figure 3c As shown in the figure, there is no need to add an additional display chip as mentioned above Figure 3d The additional angle-selective film layer shown can reduce the probability of non-projection light beams entering the projection lens and improve the projection contrast without sacrificing volume, cost and weight as much as possible.

[0094] In addition, Figure 3e Compared with the prism structure shown, Figure 4 The prismatic structure shown can have a smaller volume. For example, see Figure 5 , showing by way of example Figure 4 The prism structure shown is Figure 3e Schematic diagram of volume comparison of the prism structure shown. Figure 5 (A) shows Figure 3e The prism structure shown, Figure 5 (B) shows Figure 4 The prism structure shown. Figure 5 Middle (A) and Figure 5 From (B), we can see that Figure 4The prism structure shown can be considered as Figure 5 The bold black line shown in (A) will Figure 3e The upper half, about 1 / 4 of the left side and about 1 / 4 of the right side of the prism structure shown are cut off, and the top surface of the cut prism structure is painted black. It can be seen that Figure 4 The illustrated base length and height of the prism structure are both longer than Figure 3e The prism structure shown is short. For example, through actual product measurements, Figure 4 The length of the base of the prism structure shown is compared to Figure 3e The prismatic structure shown is reduced by about 28%, Figure 4 The volume of the prismatic structure shown is compared to Figure 3e The prism structure shown saves about 58%, which greatly saves the volume and weight of the prism structure. In addition, since the length of the bottom side of the prism structure is reduced, the length from the bottom side of the prism structure to the subsequent projection lens can also be shortened accordingly, which also helps to reduce the back focus length of the optical display device, thereby helping to reduce the design difficulty of the back focus system.

[0095] The above content introduces the prism structure. The present application also provides an optical system, which is introduced in detail below.

[0096] See also Figure 6 , exemplarily showing a schematic diagram of an optical path 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 of the figure). 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 Blackened. Understandably, Figure 6 The example in which the first direction is the bottom of the figure, the second direction is the right of the figure, and the third direction is the upper left of the figure is taken as an example, but the first direction, the second direction or the third direction can also be any other or any multiple directions, such as top, bottom, left, right, upper left, lower left, upper right, lower right, any or any multiple directions, without specific limitation.

[0097] Please continue reading Figure 6When 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 L after one or more reflections or refractions in the second layer Q2. 24 , with the fourth side L painted black 24 Alternatively, it can be guided to the first layer Q1 through one or more reflections or refractions in the second layer Q2, and then the first layer Q1 guides the non-projection light beam incident therein out of the prism structure 620, for example, out of the upper left corner position X in the figure. It can be seen that the optical system can guide the non-projection light beam to the blackened prism surface for absorption or out of 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.

[0098] 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. 24 For example, please continue to see Figure 6 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 part (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 of the second layer Q2, which is used to suppress the non-projection light beams that are not reflected to the second layer Q2, further eliminate the non-projection light beams in the optical system, and reduce the influence of stray light in the optical system.

[0099] It should be noted that Figure 6 Three illumination beams are used as an example, but the actual illumination beams may be any one or any number of beams, and their directions may be the same as or different from the illustrated diagram. In addition, the display chip 630 may reflect each illumination beam to obtain a projection beam and a non-projection beam, and the projection beam and the non-projection beam obtained by reflecting the same illumination beam have different exit angles, and the projection beams or the non-projection beams obtained by reflecting different illumination beams have different positions but the same exit angles.

[0100] Below Figure 6 Each functional component and structure involved is introduced and explained separately to provide an exemplary specific implementation scheme.

[0101] 1. Light source

[0102] In a possible implementation, the light source 610 may be a semiconductor light source, which means that the light source 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). Generally, semiconductor light sources have the advantages of high electro-optical conversion efficiency, good reliability, high brightness, good color, low energy consumption, long life, and small size.

[0103] 2. Prism structure

[0104] It can be understood that the prism structure 620 can be the aforementioned Figure 4 The prism structure shown may also be other prism structures, for example, it may also 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, etc. It should be understood that any prism structure that can absorb non-projection light beams by blackening the prism surface is within the protection scope of this application.

[0105] For ease of description, the prism structure 620 is used as the Figure 4 The prism structure shown in FIG. 6 is used as an example for description. In this case, the first layer Q1 of the prism structure 620 can be considered as Figure 4 The first prism P1 in the prism structure shown, the second layer Q2 of the prism structure 620 can be considered as Figure 4 The quadrangular prism P2 in the prism structure shown, the third layer Q3 of the prism structure 620 can be considered as Figure 4 The second prism P3 in the prism structure shown.

[0106] In one possible implementation, see Figure 4 , the angle between the first side surface of the prism P2 and the third side surface of the prism P2 may be 45°. Figure 6The 45° angle can mirror the display chip 630 located below the prism structure 620 to the left of the prism structure 620 as shown in the figure, so that the mirrored display chip 630 and the projection lens 640 located to the right of the prism structure 620 as shown in the figure can be on the same axis. Therefore, the projection light beam reflected by the display chip 630 is equivalent to being transmitted to the projection lens 640 in a straight line in the horizontal direction as shown in the figure, which can reduce the probability of deformation or dislocation of the projection light beam and improve the imaging quality of the projection lens 640.

[0107] For further possible implementations, see Figure 4 , the second side surface of the second prism P3 is perpendicular to the third side surface of the second prism P3. Figure 6 After the projection light beam reflected by the quadrangular prism P2 enters the second prism P3 in the horizontal direction as shown in the figure, it is emitted from the second side surface of the second prism P3. Since the second side surface of the second prism P3 is perpendicular to its third side surface, the second side surface of the second prism P3 can be considered as a vertical surface, which can ensure that the emission direction of the horizontally incident projection light beam does not change as much as possible.

[0108] In one possible implementation, please refer to Figure 4 and Figure 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, and the display chip 630 is located below the plane as shown in the figure. In this way, according to the arrangement shown in the figure, 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, and setting it in a flat shape is not only more beautiful, but also allows the light beam reflected by the display chip 630 to refract into the quadrangular prism P2 and the second triangular prism P3 at the same vertical position, which is convenient for realizing the design of the light transmission path.

[0109] In one possible implementation, please refer to Figure 4 and Figure 6 , the third side surface of the prism P2 is parallel to the fourth side surface of the prism P2, and the area of ​​the third side surface of the prism P2 is greater than the area of ​​the fourth side surface of the prism P2. Thus, according to the arrangement shown in the figure, the third side surface of the prism P2 serves as the bottom surface of the prism structure 620, and the fourth side surface of the prism P2 serves as the top surface of the prism structure 620. The bottom surface has a larger area, which helps to make the prism structure 620 more stable.

[0110] In a possible implementation, in addition to the fourth side L of the prism P2 24 In addition to blackening, non-effective light path portions of one or more other outer surfaces of the prism structure 620 may also be blackened. Figure 7aConsidering that the light beam is basically not transmitted in the front-to-back direction as shown in the figure, the main surface in the front-to-back direction is ignored, and the entire prism structure except the fourth side L of the quadrangular prism P2 24 The external surfaces may include the following five:

[0111] 1. The first side surface L of the first prism P1 11 .

[0112] like Figure 7a , on the first side L of the first prism P1 11 In the embodiment, except for the surface used to receive the illumination light beam, the other surfaces can be considered as surfaces corresponding to non-effective light paths, and such surfaces can be painted black.

[0113] It should be noted that although some non-projection light beams also pass through the first side surface L of the first prism P1 11 For example, in the above optical system design, some non-projected beams will be Figure 7a The first side L 11 However, after the position is painted black, the non-projection light beam directed to this position can be directly absorbed by the black surface without being further guided out. 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 exporting the non-projection light beam into a method of absorbing the non-projection light beam.

[0114] 2. The third side surface L of the first prism P1 13 .

[0115] like Figure 7a , 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.

[0116] 3. The third side L of the prism P2 23 .

[0117] like Figure 7a , on the third side L of the prism P2 23 In the figure, except for 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 the non-projection light beam reflected by the display chip 630, other surfaces can be considered as surfaces corresponding to non-effective light paths, and these surfaces can be painted black.

[0118] Optionally, considering the third side L of the prism P2 23Most 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 making the prism.

[0119] 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. Figure 7b As shown in FIG. 1 , part of the non-projection light beam reflected by the display chip 630 can be directly projected by the third side surface L of the prism P2. 23 The black-painted portion is absorbed by the prism P2 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, which can reduce 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.

[0120] 4. The third side surface L of the second prism P3 33 .

[0121] like Figure 7a , on the third side L of the second prism P3 33 In the embodiment, except for the surface used to receive the non-projection light beam reflected by the display chip 630, other surfaces can be considered as surfaces corresponding to non-effective light paths, and such surfaces can be painted black.

[0122] 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 may be directly painted black. 33 , see Figure 7b As shown. 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 may 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.

[0123] 5. The second side surface L of the second prism P3 32 .

[0124] like Figure 7a , on the second side L of the second prism P3 32 In addition to the surface used to guide the projection beam to the projection lens 640, other surfaces can be considered as surfaces corresponding to non-effective light paths, and these surfaces can be painted black. Optionally, since most of the second side surface needs to be used to guide the projection beam, it may not be easy to find the position of the non-effective light path part. Therefore, in order to reduce the difficulty of production, the surface may not be painted black.

[0125] 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, thereby reducing the probability of generating stray light in the projection lens.

[0126] 3. Display chip

[0127] In a 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. Among them, the display chip 630 can usually contain hundreds of thousands or even millions of micro-lenses, each micro-lens corresponds to a pixel on the image, and 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 (digital micromirror device, DMD), liquid crystal display (liquid crystal display, LCD) chips, liquid crystal on silicon (liquid crystal on silicon, LCOS) chips, or laser beam scanning (laser beam scanning, LBS) displays, etc.

[0128] Taking the DMD chip as an example, each micro-lens 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 may include "on", "off" and "flat". Specifically, for a frame of image, some areas are brighter and some areas are darker. The pixels on the image with brightness greater than or equal to the brightness threshold are called bright spots, and the pixels with brightness less than the brightness threshold are called dark spots. Please refer to Figure 8aWhen 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. In addition, after projecting one frame of the image, when projecting the next frame of the image, the bright and dark areas on the image may change, resulting in changes in the bright spots and dark spots on the image. Some of the previous bright spots may become dark spots, and some of the 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. Normally, the deflection angle corresponding to the "on" state and the deflection angle corresponding to the "off" state are opposite relative to the plane where the DMD chip is located. For example, please continue to refer to Figure 8a , assuming that the deflection angle corresponding to the "on" state is an angle of 12° counterclockwise rotation relative to the plane where the DMD chip is located, and the deflection angle corresponding to the "off" state is an angle of 12° clockwise rotation 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.

[0129] For further information, see Figure 8b , assuming that when light (or light beam) is incident on the DMD chip, the micro lens 1 on the DMD chip is at the deflection angle corresponding to the "on" state, the micro lens 2 is at the deflection angle corresponding to the "flat" state, and the micro lens 3 is at the deflection angle corresponding to the "off" state, then the micro lens 1 will reflect the incident light (or light beam) at the deflection angle corresponding to the "on" state to form an "on" state light (or "on" state light beam), the micro lens 2 will reflect the incident light (or light beam) at the deflection angle corresponding to the "flat" state to form a "flat" state light (or "flat" state light beam), and the micro lens 3 will reflect the incident light (or light beam) at the deflection angle corresponding to the "off" state to form an "off" state light (or "off" state light beam). Among them, 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.

[0130] In addition, taking light as an example, since the "on" state light, "flat" state light and "off" state light are obtained by the micro-mirrors 1, 2 and 3 at different deflection angles reflecting the light of the same incident angle, the three states of light have different exit angles relative to the plane where the DMD chip is located. For example, please continue to refer to Figure 8b According to the deflection method shown in the figure, the sizes of the exit angles of the light in these three states can satisfy the following relationship: the exit angle α1 of the light in the “on” state < the exit angle α2 of the light in the “flat” state < the exit angle α3 of the light in the “off” state.

[0131] Based on the above content, in a possible implementation, the projection beam may include the beam reflected by the display chip 630 at the first deflection angle, and the non-projection beam may include the beam reflected by the display chip 630 at the second deflection angle and the beam reflected by the display chip 630 at the third deflection angle, wherein the first deflection angle, the second deflection angle and the third deflection angle correspond to three different deflection states of the display chip 630. For example, taking the display chip 630 as a DMD chip as an example, in an ideal state, we hope that only the beam corresponding to the bright spot can enter the projection lens for imaging, and the beam other than the bright spot should not enter the projection lens for imaging, 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 projection beam may include the aforementioned "on" state beam, and the non-projection beam may include the aforementioned "off" state beam and the aforementioned "flat" state beam.

[0132] Further, the prism structure 620 can be used to suppress the "off" state beam and the "flat" state beam. For example, see Fig. 9 , exemplarily showing a schematic diagram of a beam transmission path provided by the present application, wherein, Fig. 9 (A) shows the overall transmission path of the light beam in each state. Fig. 9 Middle (B) to Fig. 9 (E) shows the transmission paths of the light beams in each state. Specifically, Fig. 9 (B) shows the transmission path of the illumination beam. Fig. 9 (C) shows the transmission path of the light beam in the "on" state. Fig. 9 (D) shows the transmission path of the light beam in the "flat" state. Fig. 9 The transmission path of the light beam in the "off" state is shown in (E). Fig. 9 Middle (B) to Fig. 9 Middle (E) describes in detail the transmission paths of light beams in different states on the prism structure 620 and the display chip 630 .

[0133] First, see Fig. 9 In (B), the illumination light beam passes through the first 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 prism P1, refracts into the interior of the first prism P1 on the first side surface of the first prism P1, and is transmitted to the second side surface of the first prism P1 inside, and then refracts out on the second side surface of the first prism P1, passes through the thinner air layer between the second side surface of the first prism P1 and the first side surface of the quadrangular prism P2, refracts into the interior of the quadrangular prism P2 on the first side surface of the quadrangular prism P2, and then is transmitted to the third side surface of the quadrangular prism P2 inside the quadrangular prism P2, and refracts out from the third side surface of the quadrangular prism P2, and after being transmitted through the intermediate air layer, hits the display chip 630.

[0134] Second, see Fig. 9 In (C), on the display chip 630, the micro-mirror in the "on" state corresponds to the deflection angle (not shown in the figure, please refer to Figure 8b ) reflects the illumination beam into an "on" state beam, and the "on" state beam enters the prism P3 after one or more reflections or one or more refractions in the prism P2, and then is guided out to the projection lens 640 on the second side surface of the prism P3. Optionally, according to the arrangement shown in the figure, the "on" state beam reflected by the display chip 630 can be reflected to the third side surface of the prism P2 along the vertical direction shown in the figure, that is, the center light in the "on" state beam on the display chip 630 has an exit angle of 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 from the interior of 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 thin 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 from the interior of 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 to enter 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 the energy waste of the projection light beam.

[0135] Furthermore, please see Fig. 9In (D), on the display chip 630, the micro-mirror in the "flat" state corresponds to the deflection angle (not shown in the figure, please refer to Figure 8b ) reflects the illumination beam into a "flat" state beam. After one or more reflections or one or more refractions in the prism P2, part of the "flat" state beam is guided to the fourth side surface L painted black on the prism P2. 24 is absorbed, and part 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 emission angle of the "flat" state light beam on the display chip 630 is greater than the emission 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) is 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 projected to 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, most of which is 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 part 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, and after passing through the thin air layer between the first side surface of the prism P2 and the second side surface of the first prism P1, it is refracted on the second side surface of the first prism P1 and enters the interior of the first prism P1, and is transmitted from the interior of the first prism P1 to the first side surface of the first prism P1, and refracted out from the first side surface of the first prism P1, as shown in the figure at position X. It can be seen that in the 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.

[0136] Finally, see Fig. 9 In the middle (E), on the display chip 630, the micro-mirror in the "off" state corresponds to the deflection angle (not shown in the figure, please refer to Figure 8b) reflects the illumination beam into an "off" state beam. After one or more reflections or one or more refractions in the quadrangular prism P2 and the second prism P3, the "off" state beam is guided to the fourth side surface L of the quadrangular prism P2 which is painted black. 24 . Optionally, according to the arrangement shown in the figure, the "off" state light beam reflected by the display chip 630 is also reflected to the third side surface of the prism P2 along the upper right direction shown in the figure, and the emission angle of the "off" state light beam on the display chip 630 is greater than the emission angle of the "flat" state light beam on the display chip 630. Most of the "off" state light beam (such as the two "off" state light beams on the left) is refracted on the third side surface of the prism P2 and enters 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 projected to 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 After 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, it is 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 entering 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 thinner 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, and then transmitted from the interior of the quadrangular prism P2 to the fourth side surface L of the quadrangular prism P2. 24It can be seen that in the optical transmission path, the "off" state light beam reflected into the second prism P3 can be guided to the blackened surface of the prism P2 through one or two reflections in the second prism P3, so that the transmission path of the "off" state light beam from entering the second prism P3 to being eliminated is shorter, which can reduce the probability of stray light introduced by the "off" state light beam being reflected or refracted multiple times in the second prism P3.

[0137] According to the above content, it can be known that by designing the above optical system, the "off" state light beam and the "flat" state light beam reflected by the display chip can be guided out to the black-coated 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, these two invalid light beams can be prevented 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.

[0138] It should be noted that, in the above content, the emission angle of the “flat” state light beam on the display chip 630 is greater than the emission angle of the “on” state light beam on the display chip 630, and the emission angle of the “off” state light beam on the display chip 630 is greater than the emission angle of the “flat” state light beam on the display chip 630. It can be understood that the emission angle of the “flat” state light beam with the smallest emission angle in the “flat” state light beam on the display chip 630 is greater than the emission angle of the “on” state light beam with the largest emission angle in the “on” state light beam on the display chip 630, and the emission angle of the “off” state light beam with the smallest emission angle in the “off” state light beam on the display chip 630 is greater than the emission angle of the “flat” state light beam with the largest emission angle in the “flat” state light beam on the display chip 630. In this way, there may be 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, so that there is a certain interval between the three light beams, such as Fig. 9 As shown in (A), it is precisely because of this non-overlapping angle characteristic that the three-state light beam separation through reflection or refraction in the prism structure 620 is supported.

[0139] In addition, according to Fig. 9In the arrangement shown, after being totally reflected from the first side surface of the prism P2, the magnitude relationship of the incident angles of the "on" state light beam, the "flat" state light beam, and the "off" state light beam irradiated on the second side surface of the prism P2 can be maintained the same as the magnitude relationship of the exit angles of the "on" state light beam, the "flat" state light beam, and the "off" state light beam reflected from the display chip 430. That is, the incident angle of the "on" state light beam on the second side surface of the prism P2 is smaller than the incident angle of the "flat" state light beam on the second side surface of the prism P2, and the incident angle of the "flat" state light beam on the second side surface of the prism P2 is smaller than the incident angle of the "off" state light beam on the second side surface of the prism P2. In this way, the smaller the incident angle of the "on" state light beam on the second side surface of the prism P2, the more likely it is to be smaller than the total reflection critical angle corresponding to the second side surface of the prism P2, and the easier it is to achieve the refraction of the "on" state light beam on the second side surface of the prism P2. Furthermore, the larger 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 it is greater than the critical angle of total reflection corresponding to the second side surface of the prism P2, and the easier it is to achieve total 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 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 use the critical angle of total reflection of the second side surface of the prism P2 to separate the projection light beam and the non-projection light beam.

[0140] Furthermore, to implement in the prism structure 620 Fig. 9 As shown in the optical transmission path, the prism structure 620 also needs to have some other characteristics, which are described in detail below.

[0141] In one possible implementation, see Fig. 9 In this optical system, the first prism P1, the quadrangular prism P2 and the second prism P3 are optically dense media, and the air is an optically sparse medium. Therefore, when a light beam enters the air from one side of any prism, it is equivalent to the light beam entering the optically sparse medium from the optically dense medium, and the side will correspond to a total reflection critical angle. For example, according to Fig. 9 The optical transmission path shown in the figure may include the following five sides corresponding to the critical angle of total reflection:

[0142] a1, the second side surface of the first prism P1.

[0143] For details, please refer to Fig. 9In (B), 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 irradiating 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.

[0144] a2, the third side surface of the prism P2.

[0145] For details, please refer to Fig. 9 In (B), 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 irradiating 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.

[0146] a3, a first side surface of the prism P2.

[0147] For details, please refer to Fig. 9 Middle (C) to Fig. 9In (E), 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 (called the first part 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 part of the non-projection light beam (called the second part 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 part 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 part 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 reflection in the aforementioned term explanation section, the incident angle of the first part of the non-projection light beam and the entire light beam reflected by the display chip 630 to the first side surface of the prism P2 is greater than or equal to the critical angle of total reflection corresponding to the first side surface of the prism P2, and the incident angle of the second part of the non-projection light beam to the first side surface of the prism P2 is less than the critical angle of total reflection corresponding to the first side surface of the prism P2. Among them, the critical angle of total reflection corresponding to the first side surface of the 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.

[0148] a4, the second side surface of the prism P2.

[0149] For details, please refer to Fig. 9 Middle (C) to Fig. 9 In (E), the projection light beam (such as the "on" state light beam) reflected from the first side surface of the prism P2 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 (such as the "flat" state light beam and the "off" state light beam) reflected from the first side surface of the prism P2 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 total reflection critical angle 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 total reflection critical angle corresponding to the second side surface of the prism P2. Among them, the total reflection critical angle 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.

[0150] It can be understood that the projection light beam contains a plurality of projection light rays, and the incident angle of the projection light beam irradiating the second side surface of the prism P2 is less than the total reflection critical angle corresponding to the second side surface of the prism P2. It can be considered that the incident angle of the projection light ray with the largest incident angle in the projection light beam irradiating the second side surface of the prism P2 is less than the total reflection critical angle corresponding to the second side surface of the prism P2. Similarly, the non-projection light beam contains a plurality of non-projection light rays, 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 total reflection critical angle corresponding to the second side surface of the prism P2. It can be considered that the incident angle of the non-projection light ray with the smallest incident angle in the non-projection light beam irradiating the second side surface of the prism P2 is greater than or equal to the total reflection critical angle corresponding to the second side surface of the prism P2.

[0151] a5, the second side surface of the second prism P3.

[0152] For details, please refer to Fig. 9 Middle (C) and Fig. 9 In (E), 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 quadrangular 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 total reflection critical angle 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 total reflection critical angle corresponding to the second side surface of the second prism P3. Among them, the total reflection critical angle 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.

[0153] Furthermore, in addition to the above five sides, in any of the remaining sides, the light beam will be refracted from the air through the side and enter the corresponding prism. Fig. 9 The remaining sides of the optical transmission path shown may include the following five sides:

[0154] b1, a first side surface of the first prism P1.

[0155] For details, please refer to Fig. 9 In (B), the illumination light beam transmitted in the air will be refracted from the first side surface of the first prism P1 to the inside 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.

[0156] b2, the first side surface of the prism P2.

[0157] For details, please refer to Fig. 9 In (B), the illumination light beam emitted from the second side surface of the first prism P1 is 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.

[0158] b3, the third side surface of the prism P2.

[0159] For details, please refer to Fig. 9 Middle (C) to Fig. 9 In (E), 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, the projection light beam and the non-projection light beam can both pass through the third side surface of the prism P2 without being totally reflected by the third side surface.

[0160] b4, the first side surface of the second prism P3.

[0161] For details, please refer to Fig. 9 In (C), 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 inside 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.

[0162] b5, the third side surface of the second prism P3.

[0163] For details, please refer to Fig. 9 In (E), 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 inside 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.

[0164] It is understandable that a prism can usually be made uniformly of the same material, in which case the refractive index of each side of the prism is the same. For example, when the first prism P1 is made uniformly of the same material as a whole, the refractive index n of the first side of the first prism P1 involved in the above content 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 prism P1 p13 The refractive index of any side surface of the first prism P1 can also be referred to as 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 And, 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 involved in the above content 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 referred to as the refractive index n of the second prism P3. p3 .

[0165] It can be understood that, according to the above content, the transmission path of each state light beam 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 each state light beam 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 realized on any side surface of each prism to make the side surface and nearby materials 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, and then according to the content of 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 introduced in the above-mentioned part a4, the range of the critical angle of total reflection that can achieve this function is determined, and then according to 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 the above-mentioned part a4, the refractive index range corresponding to the second side of the prism P2 is calculated, and then one or more materials with a refractive index within the 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 produced can achieve the effect of refracting the projection beam and reflecting the non-projection beam. Alternatively, in the case of consistent prism materials, the material with the corresponding refractive index can also 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, one can first calculate the three refractive index ranges that satisfy the first side of the prism P2 refracting the illumination light, satisfy the second side of the prism P2 reflecting the projection light beam and the non-projection light beam, and satisfy the third side of the prism P2 refracting the projection light beam and reflecting the non-projection light beam according to the method of calculating the refractive index range corresponding to any prism side given above, and 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 manufactured prism P2 can meet the requirements of each side refracting or reflecting the light beam.

[0166] 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 surface in the prism structure 620. Therefore, the inclination angle of the prism side surface 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 larger the inclination angle of the side surface, the larger the incident angle of the incident light beam on the side surface. For example, still taking the second side surface of the quadrangular prism P2 as an example, Fig.10A schematic diagram showing the same light irradiating the second side surface at different inclination angles. When the inclination angle of the second side surface of the prism P2 is Fig.10 When γ1 is shown in (A), the incident angle of a certain light reflected from the first side surface of the prism P2 on the second side surface of the prism P2 is β1, but when the inclination angle of the second side surface of the prism P2 decreases to Fig.10 When γ2 is shown in (B), the incident angle of the same light irradiated on the second side surface of the prism P2 becomes larger to β2. It can be seen that as the inclination angle of the second side surface of the prism P2 becomes larger, the incident angle of the same light irradiated on the second side surface of the prism P2 also becomes larger, and the probability that the incident angle exceeds the total reflection critical angle corresponding to the second side surface of the prism P2 also becomes larger, so the probability that the light is totally reflected by the second side surface of the prism P2 without being refracted also becomes larger. Therefore, when designing the second side surface of the prism P2, the corresponding inclination angle on the second side surface of the prism P2 can be selected with reference to the incident angle of each light beam irradiated on the second side surface of the prism P2, the total reflection critical angle of the second side surface of the prism P2, and the reflection or refraction path of each light beam on the second side surface of the prism P2. For example, in a possible implementation, the incident angles of the projection beam and the non-projection beam corresponding to the second side surface of the prism P2 at various different tilt angles can be first tested experimentally, and then the tilt angles that satisfy 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 are selected from the various tilt angles, and then a tilt angle is selected from these tilt angles that meet the conditions as the tilt angle of the second side surface of the prism. The selected tilt angle can be a randomly selected one, or one of the angle values ​​selected from those tilt angles that meet the conditions, or one of the smallest or largest angle values ​​selected from those tilt angles that meet the conditions, and so on, without specific limitation.

[0167] In a possible implementation, the refractive index of the quadrangular prism P2 is the same as the refractive index of the second triangular prism P3. Fig. 9In (C), the "on" state light beam will sequentially pass through the second side surface of the prism P2, the air, and the first side surface of the second prism P3 to enter the second prism P3. Since the refractive index of the prism P2 is the same as that of the second prism P3, it is equivalent to that the "on" state light beam first refracts from the second side surface of the prism P2 into the air at the refractive index, and then refracts from the air into the first side surface of the second prism P3 at the reverse refractive index. Therefore, the direction in which the "on" state light beam refracts into the second prism P3 can be kept consistent with the direction emitted from the prism P2. In this way, the second side surface of the prism P2 and the first side surface of the second prism P3 that 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.

[0168] It should be noted that the refractive index of the first prism P1 may be the same as the refractive index of the quadrangular prism P2 and the second prism P3, or may be different from the refractive index of the quadrangular prism P2 and the second prism P3, and there is no specific limitation.

[0169] in addition, Fig. 9 This is just an example of a possible light path transmission method, and other light path transmission methods may also be presented in actual optical systems. For example, when the placement position of the display chip 630 changes, the position and angle relationship of the projection light beam and the non-projection light beam reflected by the display chip 630 to 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 black-coated 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, such optical systems are within the protection scope of this application, and this application does not make specific limitations on this.

[0170] 4. Projection lens

[0171] 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 can include one or more lenses, such as: Fig.11 The schematic diagram of the structure of a projection lens is shown as an example. This example takes the projection lens 640 including 10 lenses as an example, 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 are high and the requirements for projection field of view are large, 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.

[0172] In an optional implementation, 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. 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 can be the lens closest to the second prism P3 in the projection lens 640. The lens can be fixedly arranged or integrated with the second prism P3. For example, refer to Fig.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 side can be made into the right side surface of the last lens.

[0173] For further optional implementations, please continue to refer to Fig.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 illustrated left side surface of the last lens can be controlled to be a plane, specifically, it can be controlled to be a plane parallel to and of the same size as the third side surface (i.e., the illustrated right side surface) of the second prism P3. In this way, when fixing the second prism P3 and the last lens, the illustrated right side surface of the last lens can be directly attached to the illustrated left side surface of the second prism P3, and glue can be used to bond them, so that it is easier to fix.

[0174] It can be understood that the back focal length of the optical system is the distance of the projection light beam from the plane where the display chip 630 is located to the last lens of the projection lens 640. For example, see Fig.13 , specifically, it can be the sum of the distance h1 of the projection light beam reflected from the plane where the display chip 630 is located to the second side surface of the prism P2, the distance h2 of the projection light beam reflected from the second side surface of the prism P2 to the second side surface of the second prism P3, and the distance of the projection light beam transmitted from the second side surface of the second prism P3 to the last lens of the projection lens 640. When the last lens is fixedly arranged or integrated with the second prism P3, the distance of the projection light beam transmitted from the second side surface of the second prism P3 to the last lens of the projection lens 640 is zero. Compared with the solution in which the last lens is not fixedly arranged or integrated with the second prism P3, this method can reduce the back focus distance of the optical system, thereby reducing the difficulty of designing the back focus system.

[0175] The above content introduces 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 evenly process the illumination light beam emitted by the light source 610 so that the energy of the illumination light beam can be evenly distributed on the display chip 630.

[0176] In addition, the light beam mentioned in this application refers to a collection of light including multiple light rays. Among them, the multiple light rays can be evenly distributed or unevenly distributed. Although many drawings of this application use a uniformly distributed form to reflect the light beam, this is only for the convenience of presentation and does not constitute a limiting scheme of this application.

[0177] Based on the structure and functional principle 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 in 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 may be used to reflect the illumination light beam introduced from the prism structure at different deflection angles, and the projection lens may be used to project an enlarged image according to the projection light beam introduced by the prism structure.

[0178] In a possible implementation, the optical display device may further include a light source, such as the aforementioned light source 610. The light source is used to emit an illumination beam to the prism structure 610. Specifically, the illumination beam may be emitted to the first side surface of the first prism P1.

[0179] 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.

[0180] It is understandable that the optical display device may also include other possible structures, which are not limited in this application. Fig.14, is a circuit diagram of an optical display device provided by the present application. The circuit in the optical display device mainly includes a 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. Among them, the main processor 1101 and its peripheral components, such as 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 and a display circuit 1110, can be connected via a bus. The main processor 1101 is also called a front-end processor.

[0181] In addition, the circuit diagrams shown in the embodiments of the present application do not constitute a specific limitation on the optical display device. In other embodiments of the present application, the optical display device may include more or fewer components than shown in the figure, or combine certain components, or split certain components, or arrange the components differently. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0182] 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), etc. Different processing units may be independent devices or integrated into one or more processors.

[0183] 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 a data storage function.

[0184] The internal memory 1103 can be used to store computer executable program codes, and the executable program codes include instructions. The internal memory 1103 may include a program storage area and a data storage area. Among them, the program storage area may 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 may store data created during the use of the optical display device (such as a phone book, world time, etc.), 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 (Universal Flash Storage, UFS), etc. The main processor 1101 executes various functional applications and data processing of the optical display device by running instructions stored in the internal memory 1103 and / or instructions stored in a memory provided in the main processor 1101.

[0185] 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, etc. The I / O interface 1108 may be connected to an audio module such as a mouse, a touch pad, a keyboard, a camera, a speaker / speaker, a microphone, etc., and may also be connected to physical buttons (such as a volume button, a brightness adjustment button, a power button, etc.) on the optical display device.

[0186] The audio module 1104 is used to convert digital audio information into analog audio signal output, and is also used to convert analog audio input into digital audio signal. The audio module 1104 can also be used to encode and decode audio signals, such as playing or recording. In some embodiments, the audio module 1104 can be arranged in the processor 1101, or some functional modules of the audio module 1104 can be arranged in the processor 1101. The optical display device can realize audio functions through the audio module 1104 and the application processor, etc. For example, music playing, calling, etc.

[0187] The video interface 1109 can receive external audio and video signals, which can be specifically 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 to the outside. 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.

[0188] The video module 1105 can decode the video input by the video interface 1109, for example, by performing H.264 decoding. The video module can also encode the video collected by the optical display device, for example, by performing H.264 encoding on the video collected by the external camera. In addition, the main processor 1101 can also decode the video input by the video interface 1109, and then output the decoded image signal to the display circuit 1110.

[0189] The display circuit 1110 and the modulator 1111 are used to display the corresponding image. Here, the projection lens and the display screen in any of the above embodiments may be located in the display circuit 1110, and the prism structure and the display chip in any of the above embodiments may be located in the modulator 1111. In this embodiment, the video interface 1109 receives an external input video source signal, and the video module 1105 decodes and / or digitally processes and outputs one or more image signals to the display circuit 1110. The display circuit 1110 drives the modulator 1111 according to the input image signal to project the incident light beam into an image, and then outputs the projected image light. In addition, the main processor 1101 may also output one or more image signals to the display circuit 1110.

[0190] The power module 1106 is used to provide power to the main processor 1101 and the light source 1112 according to the input power (e.g., direct current), and 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 embodiments.

[0191] The wireless communication module 1107 can enable the optical display device to communicate wirelessly with the outside world, and 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 (IR) and other wireless communication solutions. The wireless communication module 1107 can be one or more devices integrating at least one communication processing module. The wireless communication module 1107 receives electromagnetic waves via an antenna, 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, modulate and amplify it, and convert it into electromagnetic waves for radiation through the antenna.

[0192] In addition, in addition to being input through the video interface 1109, the video data decoded by the video module 1105 can also be wirelessly received 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.

[0193] Exemplarily, the optical display device may include but is not limited to a HUD, a projector, an AR device, a VR device, or a MR device, wherein 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 a MR helmet.

[0194] Based on the structure and functional principle of the optical display device described above, the present application may also provide a vehicle. The vehicle may include the optical display device in any of the above embodiments. Fig.15 , which is a possible functional framework diagram of a vehicle provided by the present application. Optionally, one or more of the above-mentioned components may be installed or associated separately from the vehicle 100. For example, the memory 163 may be partially or completely separated from the vehicle 100. The above-mentioned components may be communicatively coupled together in a wired and / or wireless manner.

[0195] It should be noted that Fig.15 The vehicle functional framework provided is only 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. In addition, the systems and components shown may be combined or divided in any manner, and the present application does not specifically limit this.

[0196] The above-mentioned vehicle 100 can be a car, a truck, a motorcycle, a bus, a ship, an airplane, a helicopter, a lawn mower, an entertainment vehicle, an amusement park vehicle, construction equipment, a tram, a golf cart, a train, and a cart, etc., and the present application does not limit this.

[0197] In the present 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 there may be three relationships. 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" or similar expressions refers to any combination of these items, including any combination of single 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 the present application, the character " / " generally indicates that the associated objects before and after are in an "or" relationship. In the formula of the present application, the character " / " indicates that the associated objects before and after are in a "divided" relationship. In addition, in the present application, the word "exemplarily" is used to indicate examples, illustrations or explanations. Any embodiment or design described as an "example" in this application should not be interpreted as being more preferred or more 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.

[0198] It is to be understood that the various digital numbers involved in the present application are only for the convenience of description and are not intended to limit the scope of the embodiments of the present application. The size of the sequence number of the above-mentioned processes does not mean the order of execution, and the order of execution of each process should be determined by its function and inherent logic. The terms "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, including a series of steps or units. Methods, systems, products or equipment are not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

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.

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