CN115826338A - Prism film and projection system - Google Patents

Abstract

The invention provides a prism film, which is used for splitting illumination light, wherein the illumination light comprises colored light with different wavelengths, the prism film sequentially comprises a substrate layer, a first functional layer and a second functional layer along the light path of the illumination light, the first functional layer comprises a plurality of corner units, the plurality of corner units are convexly arranged on the substrate layer, and the first functional layer is made of a first material; the second functional layer is filled among the corner units and is made of a second material, and the Abbe number of the second material is larger than that of the first material. The prism film provided by the invention can be used for splitting the illumination light comprising the colored light with different wavelengths, and has the advantages of low cost, high efficiency and simple process. The invention also provides a projection system.

Description

Prism film and projection system

Technical Field

The invention relates to the technical field of optics, in particular to a prism film and a projection system.

Background

In the field of optical projection, it is often necessary to separate incident light into a plurality of light beams to be emitted through a light splitter, so as to meet the requirements of optical instruments. The existing light splitting device is mainly a diffraction optical device, but the diffraction optical device has the problems of low efficiency, high processing precision requirement and high cost, and the light splitting requirement is difficult to meet.

Disclosure of Invention

An embodiment of the invention provides a prism film and a projection system to solve the above problems. The embodiment of the invention achieves the aim through the following technical scheme.

In a first aspect, the present invention provides a prism film, configured to split illumination light, where the illumination light includes color lights with different wavelengths, and the prism film sequentially includes a substrate layer, a first functional layer, and a second functional layer along a light path of the illumination light, where the first functional layer includes a plurality of corner units, the plurality of corner units are convexly disposed on the substrate layer, and the first functional layer is made of a first material; the second functional layer is filled among the corner units and is made of a second material, and the Abbe number of the second material is larger than that of the first material.

In a second aspect, the present invention further provides a projection system, including a light source device, a spatial light modulator, and a prism film, wherein the light source device is configured to emit illumination light; the prism film is used for dividing the illumination light into first light, second light and third light, and the first light, the second light and the third light are mutually separated in the angle direction; the spatial light modulator comprises a plurality of light modulation unit groups, the light modulation unit groups are located on the same plane, each light modulation unit group comprises a first light modulation unit, a second light modulation unit and a third light modulation unit, first light enters the first light modulation unit and is emitted after being modulated by the first light modulation unit, second light enters the second light modulation unit and is emitted after being modulated by the second light modulation unit, and third light enters the third light modulation unit and is emitted after being modulated by the third light modulation unit.

Compared with the prior art, the prism film and the projection system provided by the invention have the advantages that the prism film can be used for splitting the illumination light comprising the colored light with different wavelengths, and the prism film has the advantages of low cost, high efficiency and simple process; when the prism film is used for the spatial light modulator, the spatial light modulator can respectively modulate color lights with different wavelengths and then emit the color lights, high-efficiency illumination is achieved, and the heat load of the spatial light modulator can be reduced.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a color liquid crystal panel provided in the prior art.

Fig. 2 is a schematic structural diagram of a color filter structure of the color liquid crystal panel shown in fig. 1.

Fig. 3 is a schematic structural diagram of a prism film provided in an embodiment of the present application.

Fig. 4 is a schematic structural view of the base layer and the first functional layer of the prism film shown in fig. 3.

Fig. 5 is a graph of the tilt angle α of the prism film shown in fig. 3 as a function of the deflection angle of the light beam (red light having a dominant wavelength of 615 nm).

FIG. 6 is a plot of the magnitude of individual prism angles versus diffraction angle distance for the prismatic film shown in FIG. 3.

Fig. 7 is a schematic structural diagram of a projection system provided in an embodiment of the present application.

Fig. 8 is a schematic diagram of a single pixel area in the spatial light modulator of the projection system shown in fig. 7.

Fig. 9 is a graph showing the relationship between the tilt angle α of the prism film (when the red light is deflected by 4 degrees) and the number of layers required for the prism film in the projection system shown in fig. 7.

FIG. 10 is a schematic diagram of the structure of the microlens array of the projection system shown in FIG. 7.

Fig. 11 is a schematic structural diagram of a projection system according to another embodiment of the present application.

Fig. 12 is a schematic structural diagram of a projection system according to yet another embodiment of the present application.

Fig. 13 is a schematic structural diagram of a light source device of a projection system according to still another embodiment of the present application.

Fig. 14 is a schematic structural diagram of a projection system according to yet another embodiment of the present application.

FIG. 15 is a schematic diagram of the polarization component of the projection system shown in FIG. 14.

Detailed Description

In order to facilitate an understanding of the embodiments of the present invention, the embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the examples of the present invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

The inventor of the present application finds that, in a display system, a core principle of display is to adopt a red, green and blue three-primary-color display principle, that is, image display information of red, green and blue three primary colors needs to be respectively displayed through a light valve, and then three monochromatic images are combined in a time integration or space integration manner, so that human eyes observe single color image information.

One-piece light valve projection display systems are common projection systems that use only one-piece light valve devices and process only light intensity and no color. When an image is displayed, at the time t1, the light valve is irradiated by red light illumination light, and the red image is displayed by the light valve in a transmission or reflection mode; at the time t2, the green illumination light irradiates the light valve to display a green image; at time t3, the light valve is illuminated with blue illumination light, and a blue image is displayed. Under the condition that the switching speed is high enough at the three moments of t1, t2 and t3, the eyes of an observer can mix three monochromatic images into a color image to realize color display by virtue of the persistence effect of the eyes of the human.

The projection system of the single-chip light valve type has the advantages of simple structure and small system size. However, single-chip light valve type projection systems still have two potential problems.

First, if a white light source is used, only one monochromatic light source of red, green, and blue can be used at any time, i.e., when displaying a red image, green and blue colors need to be filtered out of the light source, resulting in low optical efficiency of the projection system.

Secondly, even if a separate color monochromatic light source is used as the illumination light, in order to ensure the display quality, the three monochromatic image information needs to be switched at a sufficiently high speed in time sequence, and thus the refresh rate of the light valve device needs to be sufficiently high. Otherwise, when there is a certain speed between the displayed image and the viewer, the viewer may see a pattern of color separation, or a pattern similar to a rainbow at the boundary of two colors.

The projection system of the three-piece light valve can solve the rainbow effect problem in principle, but the scheme of the three-piece light valve has the problems of complex light path system, high hardware cost, large system volume and the like. In addition, since a single color image is displayed by combining three single color images, the system architecture has high requirements on the brightness uniformity of each of the three light valves and the precision of the assembler (the alignment precision of the pixel size level is required and is usually less than 10 μm), and the production cost is further increased.

In addition to the typical projection system architectures mentioned above, projection systems have recently emerged that employ monolithic color liquid crystals. The color liquid crystal panel has been widely used in the display fields of televisions, computer monitors, mobile phone screens and the like for decades. As shown in fig. 1, when a white light source W enters a color liquid crystal panel, polarized light is first formed by a polarizer 410, and then passes through structures such as a transparent electrode 420, a liquid crystal layer 430, and an alignment film 440 in sequence, and light modulated by a pixelized liquid crystal finally passes through a color filter film 450 and is analyzed and polarized by a polarizer 460. The color filter structures of the adjacent pixels are shown in FIG. 2, i.e., the adjacent color filters are a red filter 510, a green filter 520, and a blue filter 530, respectively. Therefore, the color liquid crystal panel not only can regulate and control the light intensity, but also can regulate and control the color of the pixel to form the adjacent red, green and blue color sub-pixel arrangement. Although the three color pixels are spatially separated, due to the limited angular resolution of the human eye, beyond a certain distance, the observer cannot distinguish the three separated color pixels, but rather each group of red, green and blue three sub-pixels is regarded as one integral display unit, i.e. a color display image formed by spatial integration is observed. In addition, because the color liquid crystal panel can simultaneously display the pixels of three colors of red, green and blue at the same time, the rainbow effect is avoided in principle. In addition, due to the wide application of the color liquid crystal panel, the cost of the color liquid crystal panel is greatly reduced, which has a very high cost advantage, and the color liquid crystal panel is gradually applied to a projection display system in recent years, that is, an image on the color liquid crystal panel is directly enlarged through a lens for projection display.

However, the use of a single-piece color liquid crystal panel as a light valve device in a projection system still has the following problems:

(1) The illumination light will use a white light source to form different color sub-pixels through a color filter film on top of the color liquid crystal panel. Since the color filter only allows light of a specific color to pass through, light of other wavelengths will be absorbed completely, resulting in a large amount of light energy loss, for example, the light energy loss is more than 60%. Meanwhile, absorbed light is converted into heat, so that the temperature of the color liquid crystal panel is increased, and the display effect and the service life of a display chip are further influenced;

(2) The LCD panel is manufactured by two processes, namely, low Temperature Poly-Silicon (LTPS) and High Temperature Poly-Silicon (HTPS), wherein the HTPS process has High precision, the size of a liquid crystal pixel can reach less than 10 μm, but the process requirement is High, and thus the cost is High. The color liquid crystal panel generally employs an LTPS process. LTPS processes are less costly but less accurate and have larger pixel sizes, e.g., pixel sizes typically above 25 um. Under the condition of a certain resolution, the size of the whole LCD panel is larger, so that the size of a subsequent lens is larger, and finally, the size of the whole projection system is larger;

(3) The color pixels on the color liquid crystal panel are separated from each other, although in television, computer monitor or mobile phone screen display, the observer cannot distinguish the spatial color separation in consideration of the angular resolution limit of human eyes and the observation distance. However, in the projection display, since the size of the projection is usually much larger than that of the solid display screen, the phenomenon of color pixel separation is more obvious, and the viewing effect is affected.

In addition, the projection system based on the color liquid crystal panel has the following problems:

(1) In the liquid crystal panel, a matrix type conductive electrode, that is, a TFT (Thin Film Transistor) circuit, for driving liquid crystals of respective individual pixels is present. The TFT circuit is made of opaque materials, so that incident light at corresponding positions can be shielded, and partial light effect loss is caused. In addition, part of the light energy is absorbed by the TFT circuit and converted into heat. In addition, due to the existence of the TFT circuit and process limitations, in order to ensure the aperture ratio of the panel, that is, to ensure the light transmittance of the panel, the size of the liquid crystal panel is large, which results in a large size and volume of the projection system;

(2) The color liquid crystal panel adopts a group of red, green and blue pixels which are equivalent to one color pixel, so that the resolution of the liquid crystal panel is reduced to 1/3 of the intrinsic resolution;

(3) The liquid crystal panel has a low aperture ratio, and a lot of incident light is absorbed by Black Matrix between pixels, resulting in low efficiency of LCD projection.

The prior art also discloses an optical scheme that RGB pure laser is matched with a diffraction optical device to realize separation of RGB three-color light in angle, and a single micro-transparent LCD panel is matched to realize high-efficiency illumination. From the viewpoint of light sources, light sources based on RGB three-color lasers have problems of speckle and excessive cost. From the viewpoint of the optical splitter, the diffractive optical device has the problems of low efficiency and high requirement on processing precision.

In order to solve the problems of low efficiency, high processing precision requirement, too low efficiency of a single LCD system, too large volume of a 3LCD system and too high cost in the existing light splitting device, the inventor of the application provides a prism film and a single LCD projection system based on the prism film and a single micro-transmission panel. The prism film and the projection system provided by the invention are described in detail below with reference to the detailed description and the accompanying drawings.

Referring to fig. 3 and 4, the present invention provides a prism film 10 for splitting illumination light, the illumination light includes color lights with different wavelengths, the prism film 10 sequentially includes a substrate layer 11, a first functional layer 13 and a second functional layer 15 along a light path of the illumination light, the first functional layer 13 includes a plurality of corner units 132, the plurality of corner units 132 are convexly disposed on the substrate layer 11, and the first functional layer 13 is made of a first material; the second functional layer 15 is filled between the corner units 132, and the second functional layer 15 is made of a second material, and the abbe number of the second material is greater than that of the first material.

The base layer 11 may be used for providing the first functional layer 13. In this embodiment, the substrate layer 11 may be directly prepared by laser direct writing or precision lathe processing. If the demand of the substrate layer 11 is large, a large-area thin mold can be prepared, and then a roll-to-roll method is adopted to perform structural re-engraving, so that the prism film 10 can be prepared in a large area. The material of the base layer 11 may be a transparent organic material such as PC (Polycarbonate) or PMMA (poly methyl methacrylate).

The base layer 11 comprises a bottom surface 112, the bottom surface 112 being provided with the first functional layer 13. In addition, the base layer 11 further includes a back surface 114, and the back surface 114 is opposite to the bottom surface 112 and can be connected to other optical elements, for example, the back surface 114 can be adhered to other optical elements by a back adhesive, for example, adhered to an optical lens.

The first functional layer 13 is for light splitting. The first functional layer 13 may be prepared by a method of performing an overmolding process by photocuring. The first functional layer 13 is made of a first material. In this embodiment, the first material may be different from the material of the base layer 11, for example, the first material may be optical glue or glass. In other embodiments, the first material may be the same as the material of the base layer 11, that is, may be a transparent organic material such as PC or PMMA.

The first functional layer 13 includes a plurality of corner units 132, the corner units 132 are protruded from the base layer 11, and the corner units 132 are protruded from the bottom surface 112. The plurality of corner units 132 are in a corner periodic structure and are distributed on the bottom surface 112 in a linear array, the plurality of corner units 132 can be connected in sequence, and the distance between two adjacent corner units 132 can be 0.05mm-1mm. In the present embodiment, the cross section of the corner unit 132 is triangular, for example, the corner unit 132 is substantially a triangular prism structure.

Each corner element 132 includes a first surface 1321 and a second surface 1322 that are connected, each of the first surface 1321 and the second surface 1322 being connected to the bottom surface 112. Defining the included angle between first surface 1321 and second surface 1322 as α, the included angle between first surface 1321 and bottom surface 112 as β, and the included angle between second surface 1322 and bottom surface 112 as γ, α + β + γ =180 °. In this embodiment, an included angle between the first surface 1321 and the second surface 1322 is less than 90 °, that is, α < 90 °, where the selection of the angle α is related to the light deflection capability of the prism film 10, and the deflection influence of the size of the angle α on the red light is shown in fig. 5, it can be understood that, for blue light, green light, yellow light, or other light, a corresponding deflection diagram corresponding to fig. 5 can be obtained by performing a test under the same condition, here, only red light is exemplified, and details of others are not described. In the present embodiment, β ≦ 90 °, when β deviates more than 90 degrees, i.e., β is smaller, the more stray light is generated after the light passes through the prism film 10, and the system efficiency is lower. However, since β =90 ° affects the mold release efficiency of the corner element 132, β may be slightly smaller than 90 °, for example, β =85 °, in consideration of the draft angle.

In the present invention, the size of the edge unit 132 affects the film thickness and the diffraction optical efficiency of the prism film 10, and also affects the geometrical optical efficiency of the prism film 10, for example, the larger the edge, the smaller the ratio of the defects of the sharp corner to the root. However, too large an angle also causes problems of too thick a film layer of the prism film 10, waste of materials, and dispersion of light spots. The size of the corner refers to the size of the volume of the corner unit 132.

The prism film 10 can be regarded as a transmission type blazed grating in terms of structure, the center of the diffraction distribution of the prism film 10 depends on the deflection direction of the principal ray, and the interference 0 order of the prism film 10 depends on the direction of the incident light. The diffraction model of the prismatic film 10 is a multi-slit fraunhofer diffraction. The diffraction distribution formula of the prism film 10 is:

where α = π a sin θ _x /2,a is the slot width, θ _x Is the diffraction angle. With a major order large at α =0, i.e. θ _x =0, the center of the zero-order diffraction spot is the geometric optical image point.

Multi-slit diffraction is the result of the combined effects of diffraction and interference, and the angle of the interference order can be calculated by the formula d sin θ = m λ (m =0, ± 1, ± 2), where d represents the distance between the slits. Since a = d in the prism film 10, the angular distance of each interference order can be approximated by sin θ = m λ/a. The relationship between the size of each edge of the prism film 10 and the diffraction angle distance is shown in fig. 6. It can be seen that when the edge angle is too small, the angular distance of each interference order of the prism film 10 is 0.6 °, for a specific deflection angle after light with a specific wavelength passes through the prism film 10, high energy distribution occurs in two interference orders, and the difference between the two angles is large and even larger than the light deflection angle, which may cause a lot of angles to cause efficiency waste due to exceeding the range in which a single micro-transparent panel can collect.

If the light source selects RGB pure laser, the size of the edge angle and the deflection angle can be optimized, so that the interference order is superposed with the 0 level of diffraction distribution, and the highest energy utilization rate is achieved.

If the light source is selected to be a broad spectrum light such as LED or laser fluorescence, it is necessary to select a larger angle size to reduce the angle between orders and make the diffraction distribution narrower, or to appropriately increase the light deflection angle of each layer of the prism film 10 to reduce the specific gravity of diffraction, thereby minimizing the dilution of the expansion.

The second functional layer 15 is filled between the plurality of corner units 132. In this embodiment, after obtaining a plurality of corner elements 132 made of a first material, the corner elements 132 may be filled with a second material. By flat-fill is meant that the second functional layer 15 after filling is flush with the apex lines of the corner elements 132 of the first functional layer 13, or that the top surface of the second functional layer 15 is planar and higher than the apex lines of the corner elements 132, where the apex lines are the intersection of the first surface 1321 and the second surface 1322, and the intersection is parallel to the bottom surface 112.

The second functional layer 15 is made of a second material having an abbe number larger than that of the first material, and therefore, the refractive index of the first material is different from that of the second material. When the illumination light of the color lights with different wavelengths enters the prism film 10, the edge unit 132 deflects the color lights with different wavelengths to different degrees, so as to realize the light splitting of the color lights with different wavelengths, and the light splitting efficiency is high.

In summary, the prism film 10 provided by the present invention can split the illumination light including the color lights with different wavelengths, when the illumination light of the color lights with different wavelengths enters the prism film 10, the edge unit 132 deflects the color lights with different wavelengths to different degrees, thereby achieving splitting of the color lights with different wavelengths, and has the advantages of high splitting efficiency, low cost and simple process.

Referring to fig. 7 and 8, the present invention further provides a projection system 1, which includes a light source device 12, a spatial light modulator 14 and a prism film 10, wherein the light source device 12 is used for emitting illumination light; the prism film 10 serves to divide the illumination light into first light, second light, and third light, the first light, the second light, and the third light being separated from each other in an angular direction; the spatial light modulator 14 includes a plurality of light modulation unit groups 142, the plurality of light modulation unit groups 142 are located on the same plane, each light modulation unit group 142 includes a first light modulation unit 1421, a second light modulation unit 1422, and a third light modulation unit 1423, the first light enters the first light modulation unit 1421 and is emitted after being modulated by the first light modulation unit 1421, the second light enters the second light modulation unit 1422 and is emitted after being modulated by the second light modulation unit 1422, and the third light enters the third light modulation unit 1423 and is emitted after being modulated by the third light modulation unit 1423.

The light source device 12 is used to emit illumination light, for example, parallel white light. In the present embodiment, the light source device 12 forms the illumination light by a non-imaging manner, for example, the illumination light may be a light emitting source plus a collecting lens, or a light emitting source with a conrod plus a lens, or a light emitting source plus a free-form surface lens, or a light emitting source plus a reflector. In other embodiments, the illumination light is not limited to the manner of realizing the illumination light, and the purpose of finally emitting the illumination light is satisfied, and the illumination light can be formed in a non-imaging manner, for example, after the light source is homogenized by the square rod, the image at the outlet of the square rod is amplified by the optical system to form parallel white light illumination spots; or the light source is subjected to compound eye dodging, and then subjected to surface angle change through a subsequent optical system to form parallel white light illuminating spots; the image of the light-emitting surface can be directly amplified to form parallel white light illuminating spots and the like. The light source of the light source device 12 may emit LED light, laser fluorescence or RGB pure laser light.

In the present embodiment, the light source device 12 includes a light source assembly 122 and a tapered light uniformizing device 124, the light source assembly 122 is used for emitting illumination light, and the tapered light uniformizing device 124 is disposed between the light source assembly 122 and the prism film 10.

In the present embodiment, the light source assembly 122 may be a single LED light source, for example, the light source assembly 122 is a white LED, and can emit lambertian white light. The tapered light homogenizer 124 is generally in the shape of a circular truncated cone, and the tapered light homogenizer 124 is used for collecting the illumination light emitted by the light source assembly 122. The light source assembly 122 includes a light emitting surface, which is an exit surface of the illumination light.

In this embodiment, the light source apparatus 12 further includes a collimating lens 126, and the collimating lens 126 is disposed in the light exit path of the tapered dodging device 124 and can collimate the light exiting from the tapered dodging device 124. The collimating lens 126 may be a convex lens or a fresnel lens. The lambertian white light emitted by the white LED of the present embodiment is collected by the tapered light uniformizing device 124, and then collimated by the collimating lens 126 into parallel and uniform white light, wherein the angle of the parallel white light is determined by the area of the light emitting surface and the area of the illumination surface.

The prism film 10 serves to divide the illumination light into first, second, and third lights, which are separated from each other in an angular direction, that is, the illumination light is divided into three color lights separated angularly by the prism film 10, for example, the first, second, and third lights are sequentially arranged. Since the propagation distances of the first light, the second light, and the third light are short, the first light, the second light, and the third light are still uniform white light in the near field. In this embodiment, the first light is red light, the second light is green light, and the third light is blue light.

The prism film 10 is disposed between the light source device 12 and the spatial light modulator 14, the prism film 10 has a single-layer structure or a multi-layer structure, and the number of layers of the prism film 10 can be set according to actual needs. When the prism film 10 has a single-layer structure, the first functional layer 13 and the second functional layer 15 are both single-layers, and when the prism film 10 has a multi-layer structure, the first functional layer 13 and the second functional layer 15 are both multi-layers, and the layers of the first functional layer 13 and the second functional layer 15 are the same, and the first functional layers 13 and the second functional layers 15 are alternately stacked in sequence.

The refractive indices of the first and second materials for the second light are the same, for example, in the present embodiment, green light is refracted to the same extent as it sequentially passes through the first and second materials of the prism film 10, and thus no beam deflection occurs.

For example, in the present embodiment, when red light sequentially passes through the first material and the second material of the prism film 10, the red light is refracted to different degrees, so that the red light is deflected at the connection position of the first material and the second material, that is, the red light is deflected after being emitted from the corner unit 132; since the refractive index of the first material for the first light is smaller than that of the second material for the first light, the red light is deflected to one side with respect to the green light after being emitted from the corner unit 132.

For example, in the present embodiment, when the blue light sequentially passes through the first material and the second material of the prism film 10, the blue light is refracted to different degrees, and the blue light may be deflected at the connection position of the first material and the second material, that is, the blue light may be deflected after being emitted from the corner unit 132; since the refractive index of the first material for the third light is greater than the refractive index of the second material for the third light, the blue light is deflected to the other side relative to the green light after being emitted from the corner unit 132, that is, the deflection direction of the blue light is different from that of the red light, as shown in fig. 3. In short, the first light, the second light, and the third light are emitted in a divergent manner after passing through the prism film 10.

In this embodiment, to increase the deflection angle of the red light and the blue light, the included angle α between the first surface 1321 and the second surface 1322 of the corner unit 132 may be increased, or the prism film 10 with a multi-layer structure may be used. For example, when a deflection angle of 4 ° for red light is to be achieved, the relationship between the α angle of the edge unit 132 and the number of layers of the prism film 10 is as shown in fig. 9. In other embodiments, the number of layers of the prism film 10 may be determined according to the angle at which the light needs to be refracted, or the value of the α angle of the edge unit 132.

The spatial light modulator 14 includes a plurality of light modulation unit groups 142, the plurality of light modulation unit groups 142 are located on the same plane, each light modulation unit group 142 includes a first light modulation unit 1421, a second light modulation unit 1422, and a third light modulation unit 1423, a first light enters the first light modulation unit 1421 and exits after being modulated by the first light modulation unit 1421, a second light enters the second light modulation unit 1422 and exits after being modulated by the second light modulation unit 1422, and a third light enters the third light modulation unit 1423 and exits after being modulated by the third light modulation unit 1423. In this embodiment, the spatial light modulator 14 is a single transmissive liquid crystal panel, and the illumination light is polarized illumination light, so as to improve the light extraction efficiency of the transmissive liquid crystal panel. The first light modulation unit 1421, the second light modulation unit 1422, and the third light modulation unit 1423 are pixels corresponding to color light, respectively, and each light modulation unit group 142 corresponds to one pixel region.

Referring to fig. 8 and 10, the projection system 1 further includes a microlens array 16, the microlens array 16 is disposed between the prism film 10 (fig. 7) and the spatial light modulator 14 (fig. 7), and is located on the light incident side of the spatial light modulator 14, and is used for guiding the first light, the second light and the third light, which are separated from each other in the angular direction, to the first light modulation unit 1421, the second light modulation unit 1422 and the third light modulation unit 1423, respectively. The microlens array 16 and the spatial light modulator 14 are collectively considered a single micro-transparent panel.

The microlens array 16 includes a plurality of microlenses 161, and in an embodiment, each microlens 161 corresponds to one light modulation unit group 142, so that each microlens 161 can process the first light, the second light, and the third light, the efficiency of processing the colored lights with different wavelengths by the microlens 161 is improved, and the light energy utilization rate of the projection system 1 is improved. In this embodiment, the microlens 161 is made of glass.

The projection system 1 further comprises a polarizing element 17, the polarizing element 17 being arranged between the light source device 12 and the spatial light modulator 14, for example, the polarizing element 17 being arranged between the collimator lens 126 and the microlens array 16. The polarizing element 17 is used to convert the illumination light into polarized light. In this embodiment, the polarizing element 17 may be a polarizer, for example, the polarizing element 17 is a reflective polarizing film, which can transmit light with a desired polarization state and reflect other polarized light. Such as transmitting p-polarized light and reflecting s-polarized light. In this embodiment, the light emitting surface of the light source device 12 is provided with a wavelength conversion material, and after part of the polarized light is reflected by the reflective polarizing film, the polarized light sequentially passes through the collimating lens 126 and the conical light homogenizing device 124, and then passes through the wavelength conversion material incident to the light emitting surface, so as to excite the wavelength conversion material to generate a received laser, and the received laser is incident to the reflective polarizing film and participates in the light cycle of the projection system. By this light recycling, the efficiency of the projection system can be increased. For example, yellow phosphor is disposed on the light emitting surface, and the yellow phosphor can re-scatter the returned polarized light into natural light, and then participate in the light cycle of the projection system. In other embodiments, the polarizing element 17 may also be a polarizer or a nicol prism.

The projection system 1 further comprises a beam deflecting device 18 and a projection lens 19, the beam deflecting device 18 being arranged between the spatial light modulator 14 and the projection lens 19. The beam deflecting device 18 may be a tristable beam deflecting device 18, which superimposes RGB separated small pixels in time sequence, thereby achieving triple pixel expansion and reducing the influence of pixel separation on the display effect. The projection lens 19 is used for projecting and imaging the light emitted from the spatial light modulator 14. The beam deflecting device 18 may be a slide driven by an XPR (Extended Pixel Resolution) actuator, or may be an E-shift device.

The projection system 1 further comprises a polarization analyzing element (not shown) for analyzing the light emitted from the spatial light modulator 14 to filter out the desired signal light, and then the signal light is projected by the projection lens 19, for example, to a projection screen. In this embodiment, the polarization analyzing element may be provided to the spatial light modulator 14.

In this embodiment, to increase the transmittance of light through the single micro-transparent panel, the angle of the parallel white light needs to be limited. A schematic diagram of a pixel area of a single micro-transmission panel is shown in FIG. 8, where X is the pixel size and X is the effective light-passing pixel _{Light transmission} The effective light-passing pixel will be smaller than one pixel, i.e. X _{Light transmission} < X, half angle of parallel white light is theta _{Half of a body} The distance from the microlens 161 to the pixel is L, and the glass refractive index is n. Theta is required when parallel white light is incident on the spatial light modulator 14 and is just not shaded by metal wires _{Half of} ≤sin ^-1 [n*sin(tan ^-1 (X _{Light transmission} /2L))](equation 1). For example, when the panel clear pixel size is 19.2 μm, the microlens 161 to pixel distance is 0.5mm, and the glass refractive index is 1.52, θ _{Half of} When the angle is less than or equal to 1.672 degrees, the parallel white light can pass through the single micro-transparent panel and is not blocked by the metal wires in the single micro-transparent panel. I.e. to ensure that parallel white light is not blocked by metal wires in the single micro-transparent panel, theta _{Half of} Is 1.672 deg..

In this embodiment, because a single micro-transmitting panel is used, there is a more severe spread dilution of the parallel white light, especially for the blue and red light, after passing through the single micro-transmitting panel. In order to reduce the burden on the projection lens 19, it is necessary to increase the light exit angle after the light passes through the single micro-transparent panel, and therefore, it is necessary to limit the minimum value of the angle of the parallel white light and to ensure the half angle θ of the light entering the projection lens 19 _{Lens barrel} Greater than or equal to the inherent half-angle of the lens.

Assuming that the size of a pixel region is 3*X, the distance from the microlens 161 to the pixel is L, the refractive index of the glass is n, the half-angle theta of the lens of the parallel white light is _{Lens barrel} Determined by the following equation, θ _{Lens barrel} ＝sin ^-1 [n*sin(tan ^-1 (3X/2L))](equation 2), where the lens half angle refers to the half angle of the rays before entering the projection lens 19, i.e., the half angle of the rays after exiting the single micro-transparent panel.

In the projection system 1 provided by the present invention, the half angle of the lens is less than or equal to 17 degrees, otherwise the cost is high. Theta is calculated when the size of a single pixel region is 69.3 mu m, the microlens 161-to-pixel distance is 0.35mm, and the glass refractive index is 1.52 _{Lens barrel} =17 ° (according to equation 2), when θ _{Half of} If the half angle of the lens is equal to 17 degrees, which is 2.39 degrees (according to equation 1), it cannot be guaranteed that the parallel white light is not blocked by the metal wires in the single micro-transparent panel. Many projection systems use a 12 degree lens half angle, with a single pixel area size of 69.3 μm and a glass index of refraction of 1.52, and a focal length of the microlens 161 of 0.5mm, θ _{Half of a body} =1.67 °, i.e. when the half-angle of the lens is equal to 12 degrees, it can just be ensured that the parallel white light is not blocked by the metal wires in the single slightly transparent panel. Theta.theta. _{Lens barrel} When decreased, θ _{Half of a body} Also decreases, and thus can be adjusted by defining θ _{Half of a body} Minimum value of (c) to the lens half angle theta _{Lens barrel} Is defined to ensure a lens half angle theta into the projection lens 19 _{Lens barrel} Greater than or equal to the inherent half-angle of the lens, thereby reducing the burden on the projection lens 19 and prolonging the service life of the projection lens 19.

In the present embodiment, the light emitting source of the light source device 12 may emit LED light, laser fluorescence or RGB pure laser light, wherein the minimum amount of expansion is laser light. For laser, when the single micro-transmitting panel is 0.5 inches, the minimum angle of parallel white light formed by the laser is 0.057 degrees; when the single micro-transparent panel is 1 inch, the minimum angle of parallel white light is 0.028 degrees; when the single micro-transparent panel is 2 inches, the minimum angle of the parallel white light is 0.014 degrees, namely, the half angle theta of the parallel white light can be adjusted according to the actual size of the panel _{Half of} Is defined differently.

Referring to fig. 7, in the present embodiment, the illumination light emitted from the light source assembly 122 sequentially passes through the cone-shaped dodging device 124 and the collimating lens 126 to emit parallel and uniform white light, and then is converted into polarized light by the polarizing element 17, and after passing through the prism film 10, the three-color RGB light in the polarized white light is separated in an angular direction, but is still overlapped on the surface (may fall on the same plane), and after passing through the micro-lens array 16, the three-color RGB light separated in the angular direction is respectively incident to corresponding RGB pixels on the transmissive liquid crystal panel, and after exiting from the transmissive liquid crystal panel, the light beam is filtered by the analyzer to obtain the required signal light, and then is projected to the projection screen by the projection lens 19.

Referring to fig. 11, in another embodiment of the present application, a projection system 2 is adopted, where the projection system 2 includes a light source device 20, a prism film 25, a micro lens 27 and a spatial light modulator 28, where a light emitting source of the light source device 20 emits laser fluorescence, and the light source device 20 includes a light source assembly 22, a tapered dodging device 23 and a collimating lens 24, which are sequentially disposed.

The light source assembly 22 includes a laser light source 221 and a wavelength conversion element 223, the laser light source 221 is used for emitting laser light, the wavelength conversion element 223 is disposed on a light path of the laser light and is used for converting the excitation light into received laser light, and the received laser light is incident to the tapered dodging device. For example, the laser light source 221 may be a blue laser. The wavelength conversion element 223 may be provided with yellow phosphor, which emits white fluorescence after being excited by blue laser, and the white fluorescence is incident to the tapered light uniformizing device 23.

The light source assembly 22 further includes a light homogenizing element 225 and an imaging lens 227, the light homogenizing element 225 is disposed between the laser light source 221 and the wavelength conversion element 223 and is used for homogenizing laser light emitted by the laser light source, and the light homogenizing element 225 may be a fly-eye lens or a fresnel lens. The imaging lens 227 is disposed between the light uniformizing element 225 and the wavelength conversion element 223, and is used for imaging the laser light after being uniformized.

The light emitted by the laser source 221 is imaged on the wavelength conversion element 223 by the imaging lens 227 after passing through the light uniformizing of the light uniformizing piece 225, the yellow fluorescent powder on the wavelength conversion element 223 is excited by the laser, so that the wavelength conversion element 223 emits white fluorescent light, and the white fluorescent light is incident to the tapered light uniformizing device 23; the white fluorescent light is collimated into parallel and uniform white light by the collimating lens 24 after being collected by the cone-shaped light uniformizing device, the parallel and uniform white light is polarized by the polarizing element to form polarized light, the polarized white light after being polarized enters the multilayer prism film 25 and is divided into RGB (red, green, blue) three-color light which is separated upwards by the multilayer prism film 25, but the white fluorescent light is still uniform white light in a near field due to a short transmission distance. After passing through the micro lens 27, the angularly separated RGB three-color light undergoes a face angle transformation and is imaged on a corresponding pixel in the spatial light modulator 28, so that light loss of the light beam passing through the spatial light modulator 28 is minimized, high-efficiency illumination is realized, and a thermal load of the spatial light modulator 28 can be reduced.

Referring to fig. 12, in another embodiment of the present application, a projection system 3 is used, and the projection system 3 is different from the projection system 2 in that the structure of the light source device 30 is different from that of the light source device 20. The light source device 30 emits laser fluorescence, and the light source device 30 includes a laser light source 31, an imaging lens 33, a wavelength conversion element 35, and a tapered dodging device 37, which are sequentially disposed.

The laser light source 31 includes a first laser 311, a second laser 312, a third laser 313 and a laser beam combining component 314, where the first laser 311 is used to emit first laser light, the second laser 312 is used to emit second laser light, and the third laser 313 is used to emit third laser light. In this embodiment, the first laser is a red laser, the second laser is a green laser, and the third laser is a blue laser.

The laser light combining component 314 is configured to combine the first laser light, the second laser light, and the third laser light, and the combined light of the first laser light, the second laser light, and the third laser light enters the wavelength conversion element 35.

The laser light combining component 314 includes a reflecting mirror 3141, a first dichroic sheet 3143, and a second dichroic sheet 3145, which are sequentially disposed, where the reflecting mirror 3141 is configured to reflect the third laser light to the first dichroic sheet 3143. In this embodiment, the first dichroic filter 3143 is a blue-transmissive and green-reflective dichroic filter, so that blue laser light can transmit through the first dichroic filter 3143 and green laser light emitted from the second laser light is reflected by the first dichroic filter 3143. The second dichroic sheet 3145 is a cyan-transmitting and red-reflecting dichroic sheet capable of transmitting blue laser light and green laser light and reflecting red laser light. The red laser light, the green laser light, and the blue laser light are guided by the second dichroic sheet 3145, and then enter the imaging lens 33, and then enter the wavelength conversion element 35 after being imaged by the imaging lens 33, and excite the wavelength conversion material on the wavelength conversion element 35 to form the excited light. In the present embodiment, the first laser 311, the second laser 312, and the third laser 313 may cooperate with each other to emit the first light, the second light, and the third light in time sequence. For example, the first laser 311 emits the first light during the t1 period, the second laser 312 emits the second light during the t2 period, and the third laser 313 emits the third light during the t3 period, which are sequentially repeated.

The first laser 311 is used for emitting first laser light, the second laser 312 is used for emitting second laser light, the third laser 313 is used for emitting third laser light, and the first laser light, the second laser light and the third laser light are incident to the imaging lens 33 and the conical light homogenizer 37 after wavelength light combination. Since the light entering the tapered light homogenizer 37 needs a larger divergence angle and the RGB pure laser needs to eliminate the speckle, an angle gaussian scattering wheel needs to be enlarged at the entrance of the tapered light homogenizer 37, for example, a scattering wheel with a higher roughness is used, or a material layer with a larger scattering angle such as a micro-structural layer is added.

Referring to fig. 13, in another embodiment of the present application, a projection system 4 is adopted, the projection system 4 includes a light source device 40, a polarization element 41, a prism film 42 and a spatial light modulator 43, wherein a light source of the light source device 40 emits RGB pure laser light, and the light source device 40 includes a light source assembly 44 and a tapered dodging device 45. The projection system 4 is different from the projection system 2 in that the structure of the light source device 40 is different from that of the light source device 20.

The light source assembly 44 includes a first laser light source 441, a second laser light source 442, a third laser light source 443, and a light combining element 445, where the first laser light source 441 is configured to emit first laser light, the second laser light source 442 is configured to emit second laser light, the third laser light source 443 is configured to emit third laser light, the light combining element 445 is configured to combine the first laser light, the second laser light, and the third laser light, and the combined light of the first laser light, the second laser light, and the third laser light is emitted to the cone-shaped light uniformizing device 45. The light combining element 445 may be a dichroic mirror, a dichroic filter, or a light combining prism.

In the present embodiment, the light source assembly 44 further includes a light homogenizing lens 46, a first collecting lens 47, a second collecting lens 48, and a third collecting lens 49, wherein the light homogenizing lens 46 corresponds to the third laser light source 443 and is configured to homogenize the third laser light. The first collecting lens 47 corresponds to the first laser light source 441, and is configured to collect the first laser light. The second collecting lens 48 corresponds to the second laser light source 442, and collects the second laser light. The third collecting lens 49 is disposed on the light emitting path of the light combining element 445 and is used for collecting the combined light of the first laser light, the second laser light and the third laser light. The combined light enters the tapered dodging device after being collected by the third collecting lens 49.

Referring to fig. 14 and 15, in yet another embodiment of the present application, a projection system 5 is adopted, the projection system 5 includes a light source device 50, a polarizing element 53, a prism film 54 and a spatial light modulator 55, wherein a light emitting source of the light source device 50 emits LED light, and the light source device 50 includes a light source assembly 51 and a light collecting system 52. The projection system 5 differs from the projection system 1 in that the structure of the light collection system 52 differs from the structure of the tapered dodging device 23, and the structure of the polarizing element 53 differs from the structure of the polarizing element 17. The light source assembly 51 is used to emit illumination light, and the light source assembly 51 may be a single LED light source. A light collection system 52 is disposed between the light source assembly 51 and the prism film 54 for collecting the illumination light.

The light collection system 52 includes a first collection lens 521 and a second collection lens 523, wherein the first collection lens 521 is located between the second collection lens 523 and the light source assembly 51, and the size of the first collection lens 521 is smaller than that of the second collection lens 523.

In the present embodiment, the polarizing element 53 includes a light circulation region 531 and a reflective region 533, and as shown in fig. 15, the reflective region 533 surrounds and connects the light circulation region 531.

The reflection region 533 can reflect the incident light back to the light collection system 52, and the incident light is incident to the wavelength conversion material on the light emitting surface of the light source assembly 51, so as to excite the wavelength conversion material to generate the stimulated light, and the stimulated light participates in the light cycle of the projection system 5, thereby improving the efficiency of the projection system 5. In this embodiment, the reflective region 533 has a rectangular shape.

The light circulating area 531 is rectangular, the light circulating area 531 is configured to transmit light in a desired polarization state, reflect other light except the light in the desired polarization state, reflect the other light back to the light collecting system 52, make the reflected light incident on the wavelength conversion material on the light emitting surface, excite the wavelength conversion material to generate stimulated light, and make the stimulated light participate in light circulation of the projection system 5 again, so as to improve efficiency of the projection system 5.

In this embodiment, the illumination light has a projection light spot on the polarization element 53, for example, the projection light spot is a circular light spot, the light recycling region 531 is located within the range of the projection light spot, only the light in the required polarization state will pass through the light recycling region 531, other light is reflected by the polarization element 53 and participates in the light recycling of the projection system 5 again, since the light recycling region 531 is rectangular, the rectangular light spot can be cut out from the light spot, and the part of the spatial light modulator 55 that needs to be illuminated is also rectangular, which can be better matched with the rectangular light spot, and the utilization rate of the illumination light is improved.

In summary, the projection system 1 provided by the embodiment of the invention includes the prism film 10, the light source device 12 and the spatial light modulator 14, the prism film 10 divides the illumination light into the first light, the second light and the third light which are mutually separated in the angular direction, so that the first light is modulated by the first light modulation unit 1421 of the spatial light modulator 14 and then emitted, the second light is modulated by the second light modulation unit 1422 of the spatial light modulator 14 and then emitted, and the third light is modulated by the third light modulation unit 1423 of the spatial light modulator 14 and then emitted, thereby realizing high-efficiency illumination and reducing the thermal load of the spatial light modulator 14.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (18)

1. A prism film for splitting illumination light including color lights of different wavelengths, the prism film comprising, in order along an optical path of the illumination light:

a base layer;

a first functional layer comprising a plurality of corner units, the corner units being disposed in the base layer in a protruding manner, the first functional layer being made of a first material; and

the second functional layer is filled among the corner units and is made of a second material, and the Abbe number of the second material is larger than that of the first material.

2. The prismatic film of claim 1 wherein each of said prismatic cells comprises a first surface and a second surface connected, said substrate layer comprises a base surface, said first surface and said second surface both connected to said base surface, said first surface and said second surface comprising an included angle of less than 90 °.

3. The prismatic film of claim 1 wherein adjacent two of said corner elements have a pitch of 0.05mm to 1mm.

4. A projection system comprising a light source device for emitting illumination light, a spatial light modulator, and the prism film according to any one of claims 1 to 3; the prism film is used for dividing the illumination light into first light, second light and third light, and the first light, the second light and the third light are mutually separated in the angle direction; the spatial light modulator comprises a plurality of light modulation unit groups, the light modulation unit groups are located on the same plane, each light modulation unit group comprises a first light modulation unit, a second light modulation unit and a third light modulation unit, the first light enters the first light modulation unit and is emitted after being modulated by the first light modulation unit, the second light enters the second light modulation unit and is emitted after being modulated by the second light modulation unit, and the third light enters the third light modulation unit and is emitted after being modulated by the third light modulation unit.

5. The projection system of claim 4, wherein the refractive indices of the first material and the second material for the second light are the same, the refractive index of the first material for the first light is less than the refractive index of the second material for the first light, and the refractive index of the first material for the third light is greater than the refractive index of the second material for the third light.

6. The projection system of claim 4, wherein the prism film is disposed between the light source device and the spatial light modulator, and the prism film has a single-layer structure or a multi-layer structure; when the prism film is of a single-layer structure, the first functional layer and the second functional layer are both single layers, when the prism film is of a multilayer structure, the first functional layer and the second functional layer are both multilayer, the number of layers of the first functional layer and the number of layers of the second functional layer are the same, and the first functional layer and the second functional layer are sequentially and alternately stacked.

7. The projection system of claim 4, further comprising a microlens array disposed between the prism film and the spatial light modulator for directing the first light, the second light, and the third light, which are angularly separated from each other, to the first light modulation unit, the second light modulation unit, and the third light modulation unit, respectively.

8. The projection system of claim 7, wherein the microlens array comprises a plurality of microlenses, one for each of the groups of light modulating cells.

9. The projection system of any of claims 4-8, wherein the light source arrangement comprises a light source assembly for emitting the illumination light and a tapered dodging device disposed between the light source assembly and the prismatic film.

10. The projection system of claim 9, wherein the light source assembly comprises a laser light source and a wavelength conversion element, the laser light source is configured to emit laser light, the wavelength conversion element is disposed in an optical path of the laser light source and configured to convert the excitation light into stimulated light, and the stimulated light is incident on the tapered dodging device.

11. The projection system of claim 10, wherein the light source assembly further comprises a light homogenizer disposed between the laser light source and the wavelength converting element and an imaging lens disposed between the light homogenizer and the wavelength converting element.

12. The projection system of claim 10, wherein the laser light source comprises a first laser, a second laser, a third laser, and a laser light combining component, the first laser is configured to emit first laser light, the second laser is configured to emit second laser light, the third laser is configured to emit third laser light, the laser light combining component is configured to combine the first laser light, the second laser light, and the third laser light, and the combined light of the first laser light, the second laser light, and the third laser light enters the wavelength conversion element.

13. The projection system of claim 9, wherein the light source assembly comprises a first laser light source, a second laser light source, a third laser light source, and a light combining element, the first laser light source is configured to emit first laser light, the second laser light source is configured to emit second laser light, the second laser light source is configured to emit third laser light, the light combining element is configured to combine the first laser light, the second laser light, and the third laser light, and the combined light of the first laser light, the second laser light, and the third laser light is emitted to the tapered dodging device.

14. A projection system according to any of claims 4-8, further comprising a polarizing element arranged between said light source device and said spatial light modulator for converting said illumination light into polarized light.

15. The projection system of claim 14, wherein the polarizing element is a reflective polarizing film, the light source device is provided with a wavelength conversion material, a portion of the polarized light is reflected to the wavelength conversion material by the reflective polarizing film, and the wavelength conversion material is excited to generate a laser beam, and the laser beam is incident to the reflective polarizing film.

16. The projection system of claim 15, wherein the polarizing element comprises a light recycling region and a reflecting region, the reflecting region surrounds and connects the light recycling region, the light recycling region is rectangular, the illumination light has a projection spot on the polarizing element, and the light recycling region is located within a range of the projection spot.

17. The projection system of any of claims 4-8, further comprising a beam deflecting device disposed between the spatial light modulator and the projection lens, and a projection lens for projecting and imaging light emitted from the spatial light modulator.

18. The projection system of any of claims 4-8, wherein the spatial light modulator is a single transmissive liquid crystal panel.

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