Light homogenizing film applied to mini-LED array light source

Abstract

The present invention relates to a light homogenizing film applied to a mini-LED array light source, comprising: a base layer, the base layer being a light-transmitting structure; a light-emitting and reflecting composite layer located on one side of the base layer, the light-emitting and reflecting composite layer including a reflecting layer and a plurality of light-emitting elements, a plurality of accommodating holes being formed in the emitting layer, the light-emitting elements being arranged in the accommodating holes, and the light-emitting surfaces of the light-emitting elements facing the base layer; a grating layer located on the other side of the base layer, the grating layer including a plurality of pixel-type metal grating units, and the pixel-type metal grating units being arranged in one-to-one correspondence with the accommodating holes. It has uniform light output and high light energy utilization rate, converts the light emitted by the light-emitting elements into TM polarized light, can omit the polarizer assembly of the backlight module, and is beneficial to the development trend of the display system towards thinness and lightness.

Description

Technical Field

[0001] The present invention relates to the technical field of backlight display, and in particular to a light homogenizing film applied to a mini-LED array light source. Background Art

[0002] As a light source of a backlight module, the Mini-LED array has been widely used in display industries such as televisions, computers, mobile phones, and vehicles. The size of a Mini-LED chip is usually about 100um - 200um, and it is mainly applied to a direct-lit backlight display system. Compared with traditional LED light sources, it has the advantages of smaller size, lighter weight, thinner thickness, and more energy saving.

[0003] Since the divergence angle of the light emitted by a single Mini-LED point light source is limited, the energy in the central area of the light-emitting surface is high while the energy in the surrounding area is low. Moreover, the distance between chips is about 100um - 200um. Therefore, the array light composed of multiple LED chips will cause periodic bright and dark areas on the screen, resulting in poor visual effects and affecting the user experience. Existing technologies usually cover a diffusion film based on diffusion particles above the light-emitting surface of the Mini-LED to achieve light diffusion and light mixing, so as to achieve uniform light emission on the light-emitting surface. However, the light mixing distance corresponding to this method is in the range of several millimeters to several centimeters, which does not meet the requirements of future display industries for thin and light designs.

[0004] Therefore, there is an urgent need for a light homogenizing film that can achieve diffusion and homogenization of the emitted light within a smaller light mixing distance. Summary of the Invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the technical defects in the prior art that the array light has bright and dark areas, poor visual effects, and large volume.

[0006] To solve the above technical problem, the present invention provides a light homogenizing film applied to a mini-LED array light source, including:

[0007] A base layer, the base layer being a light-transmitting structure;

[0008] A light-emitting and reflecting composite layer, which is located on one side of the base layer. The light-emitting and reflecting composite layer includes a reflecting layer and a plurality of light-emitting elements. A plurality of accommodating holes are formed in the emitting layer, and the light-emitting elements are arranged in the accommodating holes, and the light-emitting surface of the light-emitting elements faces the base layer;

[0009] A grating layer, which is located on the other side of the base layer. The grating layer includes a plurality of pixelated metal grating units, and the pixelated metal grating units are arranged in one-to-one correspondence with the accommodating holes.

[0010] Preferably, the light transmittance of the pixelated metal grating unit gradually decreases from the middle to the periphery, and the middle part of the pixelated metal grating unit is a contour structure of the light-emitting element.

[0011] Preferably, the light-emitting element is an LED chip.

[0012] Preferably, a plurality of the light-emitting elements are arranged in an array.

[0013] Preferably, the pixelated metal grating unit is a one-dimensional double-layer metal grating or a one-dimensional single-layer metal grating.

[0014] Preferably, the period of the pixelated metal grating unit is less than 200 nm.

[0015] Preferably, the design method of the grating layer is as follows:

[0016] Measure the distances between each point on the pixelated metal grating unit and the corresponding light-emitting element of the pixelated metal grating unit to obtain a data set of the distances;

[0017] According to the data set of the distances and the light intensity of the light-emitting element at the pixelated metal grating unit, calculate the total transmittance of the TM-polarized light so that the light rays at each point on the metal grating unit are emitted evenly.

[0018] Preferably, the data set of the distances, the light intensity of the light-emitting element at the pixelated metal grating unit, and the total transmittance of the light homogenizing film for the TM-polarized light satisfy: wherein, I is the light intensity of the light-emitting element at a preset point on the pixelated metal grating unit, T is the total transmittance of the preset point on the light homogenizing film for the TM-polarized light, a is the distance from the light-emitting element to the preset point on the pixelated metal grating unit, and m is a constant value.

[0019] Preferably, the total transmittance T of the preset point on the light homogenizing film for the TM-polarized light satisfies:

[0020]

[0021] wherein, T0 is the transmittance of the pixelated metal grating unit for the TM-polarized light, R0 is the reflectance of the pixelated metal grating unit for the TM-polarized light, α is the reflectance of the reflective layer for reflecting the TM-polarized light that has not passed through the pixelated metal grating unit, and β is the reflectance of the TE-polarized light reflected by the pixelated metal grating unit converted into the TM-polarized light.

[0022] Preferably, the pixelated metal grating unit includes a flexible substrate, a dielectric grating, and a first metal layer disposed on the flexible substrate. The first metal layer and the dielectric grating are alternately arranged, and a second metal layer is disposed on the upper surface of the dielectric grating.

[0023] Preferably, the reflective layer is a metal reflective film or a dielectric reflective film.

[0024] The above technical solution of the present invention has the following advantages compared with the prior art:

[0025] 1. In the present invention, the light-emitting element emits light beams towards the base layer. When the light beams reach the grating layer, a part of the light is transmitted through the grating layer, and another part of the light is reflected by the grating layer and passes through the base layer, reaches the reflective layer and is reflected, and then acts on the pixelated metal grating unit again to form new transmitted light and reflected light. After multiple cycles, not only does the light homogenizing film emit light evenly, but also the light energy utilization rate is improved.

[0026] 2. In the present invention, for the light emitted from the light-emitting element, after passing through the pixelated metal grating unit, the TM polarized light is partially transmitted, and almost all of the TE polarized light is reflected. The reflective layer reflects the TM polarized light that has not been transmitted, and at the same time converts the TE polarized light reflected by the pixelated metal grating unit into TM polarized light, and then incident on the pixelated metal grating unit. After the light emitted from the light-emitting element passes through the light homogenizing film of the present invention, it is directly converted into TM polarized light and used in the display system, and there is no need to use a polarizer assembly again, which is beneficial to the thinning of the display system. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of the present invention;

[0028] Figure 2 It is a schematic distribution diagram of the pixelated metal grating unit;

[0029] Figure 3 It is a cross-sectional view of the pixelated metal grating of the light homogenizing film;

[0030] Figure 4 It is a schematic diagram of the change of the transmission efficiency of the one-dimensional double-layer metal grating with the duty ratio;

[0031] Figure 5 It is a schematic diagram of the light recycling;

[0032] Explanation of the reference numerals in the drawings: 10, light-emitting and reflecting composite layer; 11, reflective layer; 12, light-emitting element; 20, base layer; 30, grating layer; 31, pixelated metal grating unit; 32, flexible substrate; 33, first metal layer; 34, second metal layer; 35, dielectric grating. Detailed Embodiments

[0033] The present invention will be further described below with reference to the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments given are not intended to limit the present invention.

[0034] Refer to Figures 1-5As shown in the figure, the present invention discloses a light homogenizing film applied to a mini-LED array light source, which includes a base layer 20, a light-emitting and reflecting composite layer 10, and a grating layer 30.

[0035] The base layer 20 is a light-transmitting structure. The light-emitting and reflecting composite layer 10 is located on one side of the base layer 20. The light-emitting and reflecting composite layer 10 includes a reflecting layer 11 and a plurality of light-emitting elements 12. A plurality of accommodating holes are formed in the emitting layer, and the light-emitting elements 12 are arranged in the accommodating holes. The light-emitting surface of the light-emitting element 12 faces the base layer 20. The reflecting layer 11 is a metal reflecting film or a dielectric reflecting film.

[0036] The grating layer 30 is located on the other side of the base layer 20. The grating layer 30 includes a plurality of pixelated metal grating units 31, and the pixelated metal grating units 31 are arranged in one-to-one correspondence with the accommodating holes. The pixelated metal grating unit 31 can make the light irradiated thereon transmit and reflect. The working principle of the present invention is: the light-emitting element 12 emits a light beam towards the base layer 20. When the light beam reaches the grating layer 30, a part of the light is transmitted through the grating layer 30, and another part of the light is reflected by the grating layer 30 and passes through the base layer 20, reaches the reflecting layer 11 and is reflected, and then acts on the pixelated metal grating unit 31 again to form new transmitted light and reflected light. After multiple cycles, not only does the light homogenizing film emit light uniformly, but also the light energy utilization rate is improved.

[0037] The light transmittance of the pixelated metal grating unit 31 gradually decreases from the middle to the periphery, and the middle part of the pixelated metal grating unit 31 is a shape imitation structure of the light-emitting element 12. As Figure 2 shown, it is a schematic structural diagram of the pixelated metal grating unit 31 in the present invention. Specifically, the pixelated metal grating unit 31 can be set according to the shape and arrangement of the light-emitting element 12. For example, when the light-emitting element 12 includes a plurality of LED chips and the plurality of LED chips are arranged in a square, then the light at the position directly above the LED chip is relatively strong, and the light at the position far from the direct above the LED chip is relatively weak. In order to make the light emitted by the lamp beads into uniform light, the arrangement of the metal grating can be selected Figure 2 (a) The arrangement method, that is, the C area can also be set into a square structure, and the C area is located directly above the light-emitting element 12. Among them, the light transmittance of the A area is greater than that of the B area, and the light transmittance of the B area is greater than that of the C area. If the shape and arrangement of the LED chips are both rectangular, the arrangement method of Figure 2 (b) can be selected, that is, the C area is set into a rectangular structure similar to the shape of the light-emitting element 12.

[0038] The arrangement method of the pixelated metal grating unit 31 of the present invention is not limited to Figure 2Structure. During actual design, according to the shape and arrangement of the LED chips, following the principle that the light emitted from the LED chip units passes through the metal grating with uniform light output, adjust the distribution and structural parameters of the metal grating units, so as to achieve the effect of eliminating the uneven brightness between the lamp beads. Additionally, it should be noted that here only a one-dimensional double-layer metal grating is used for illustration, and the pixelated metal grating unit 31 can also be a one-dimensional single-layer metal grating, or other one-dimensional metal-dielectric composite gratings. The period of the pixelated metal grating unit 31 is less than 200 nm.

[0039] The design method of the grating layer 30 is as follows:

[0040] Measure the distances between each point on the pixelated metal grating unit 31 and the corresponding light-emitting component 12 of the pixelated metal grating unit 31 to obtain a data set of the distances;

[0041] According to the data set of the distances, the light intensity of the light-emitting component 12, and the reflectivity of the reflective layer 11, calculate the light transmittance of the metal grating unit 31 so that the light rays at each point on the metal grating unit are uniformly emitted.

[0042] According to the corresponding relationship between the light transmittance of the metal grating unit 31 and the structural parameters of the metal grating unit 31, obtain the structural parameters of each pixel of the metal grating unit 31.

[0043] In another embodiment, multiple light-emitting components 12 are arranged in an array. In this way, the light-emitting uniformity of the light homogenizing film can be further improved.

[0044] Figure 3 This is a cross-sectional view of the one-dimensional double-layer metal grating of the light homogenizing film of the present invention. The pixelated metal grating unit 31 includes a flexible substrate 32, a dielectric grating 35, and a first metal layer 33 disposed on the flexible substrate 32. The first metal layer 33 and the dielectric grating 35 are alternately arranged, and a second metal layer 34 is disposed on the upper surface of the dielectric grating 35. The second metal layer 34 can be arranged at the same height as the first metal layer 33. The flexible substrate 32 can be made very thin, only dozens of micrometers thick. In this way, the pixelated metal grating unit 31 can be made very thin, so as to achieve the diffusion and homogenization of the emitted light within a very short distance.

[0045] The period of the dielectric grating 35 is p, the ridge width is w, the duty cycle F is w / p, the height is h1, and the heights of the first metal layer 33 and the second metal layer 34 are h2. By controlling the period p, the ridge width w, the height h1 of the dielectric grating 35, and the heights h2 of the first metal layer 33 and the second metal layer 34, the light transmittance of the one-dimensional double-layer metal grating can be controlled. Considering the processing feasibility, preferably, control the ridge width of the metal grating to regulate the light transmittance of the double-layer metal grating.

[0046] Figure 4It is a schematic diagram showing that the period of the pixelated metal grating unit 31 of the present invention remains unchanged, and the light transmission efficiency varies with the duty ratio F of the one-dimensional double-layer metal grating. From Figure 4 it can be seen that as the duty ratio F increases, the transmission efficiency of the double-layer metal grating gradually increases. By adjusting other parameters of the metal grating, such as the period p and the height h1 of the metal grating, the transmission efficiency of the metal grating can also be regulated. Considering the ease of nanofabrication, adjusting the duty ratio to achieve the regulation of the transmission efficiency is the most preferred processing method. In Figure 2 (a) and (b), metal gratings with a larger duty ratio are set in the area marked with the letter A, metal gratings with a duty ratio smaller than that of area A are set in the area marked with the letter B, and metal gratings with a duty ratio smaller than that of area B are set in the area marked with the letter C, which can make the light emitted from the LED chip unit emit uniformly, thus achieving the effect of eliminating the uneven brightness between the lamp beads.

[0047] Figure 5 It is a schematic diagram of light recycling. The light emitted from the light-emitting component 12 passes through the pixelated metal grating unit 31 (such as area A). The TM-polarized light is partially transmitted (the transmittance is T0), and the TE-polarized light is almost all reflected (the reflectance is R0). The reflective layer 11 reflects the TM-polarized light that has not been transmitted (the reflectance is α), and at the same time converts the TE-polarized light reflected by the pixelated metal grating unit 31 into TM-polarized light (the conversion rate is β), and then irradiates it onto the pixelated metal grating unit 31. After multiple cycles, the total transmittance of the TM-polarized light is Not only is the light energy fully utilized, but also the uniformity of the overall light can be improved. The light emitted from the light-emitting component 12 is directly converted into TM-polarized light after passing through the light homogenizing film of the present invention and is used in the display system, and there is no need to use a polarizer assembly anymore, which is beneficial to the thinning of the display system.

[0048] Measure the distances between each pixelated metal grating on the pixelated metal grating unit and its corresponding light-emitting component to obtain a data set M1 of the distances.

[0049] Based on the rigorous coupled-wave theory and the formula for the total transmittance of TM-polarized light, determine the correspondence data set M2 between the structural parameters (including the period p of the dielectric grating 35, the ridge width w, the height h1, and the heights h2 of the first metal layer 33 and the second metal layer 34) of each pixelated metal grating of the metal grating unit and the total transmittance of the TM-polarized light.

[0050] According to the data set M1 of the distances and the light intensity distribution of the light-emitting component, based on the principle of making the light emit uniformly at each point on the metal grating unit, obtain the total transmittance of each pixel metal grating, and then according to the correspondence data set M1 between the structural parameters of each pixelated metal grating of the metal grating unit and the total transmittance of the TM-polarized light, obtain the optimal structural parameters of each pixelated metal grating.

[0051] In the present invention, the data set of distances, the light intensity of the light-emitting element at the pixelated metal grating unit, and the total transmittance of the light homogenizing film for TM-polarized light satisfy: where I is the light intensity of the light-emitting element at a preset point in the pixelated metal grating unit, T is the total transmittance of a preset point on the light homogenizing film for TM-polarized light, a is the distance from the light-emitting element to the preset point in the pixelated metal grating unit, a ∈ M1, and m is a fixed value.

[0052] Specifically, referring to Figure 1 and Figure 2 , assuming that the light intensity of the light-emitting element in the area marked with the letter A is I A , the distance between the metal grating and the light-emitting element in the area marked with the letter A is a, the light intensity of the light-emitting element in the area marked with the letter B is I B , the distance between the metal grating and the light-emitting element in the area marked with the letter A is b, the light intensity of the light-emitting element in the area marked with the letter C is I C (I A , I B , I C ∈ I), the distance between the metal grating and the light-emitting element in the area marked with the letter A is c, then to achieve uniform light output, it is necessary to satisfy Thus, the total transmittances T A , T B , T C (T A , T B , T C ∈ T) of the pixelated metal gratings in the areas marked with the letters A, B, and C can be obtained. Then, according to the data set M2 of the correspondence between the structural parameters of each pixelated metal grating of the metal grating unit and the total transmittance of TM-polarized light, the optimal structural parameters of each pixelated metal grating can be obtained.

[0053] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program code.

[0054] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one or more flows and / or one or more blocks in the flow. Figure 1 one or more flows and / or blocks Figure 1 means for implementing the functions specified in one or more blocks.

[0055] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means implements the functions specified in one or more flows and / or one or more blocks in the flow. Figure 1 one or more flows and / or blocks Figure 1 means for implementing the functions specified in one or more blocks.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows and / or one or more blocks in the flow. Figure 1 one or more flows and / or blocks Figure 1 steps for implementing the functions specified in one or more blocks.

[0057] Obviously, the above embodiments are only examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A light homogenizing film applied to a mini-LED array light source, characterized in that, Comprising: A base layer, the base layer being a light-transmitting structure; A light-emitting and reflecting composite layer, which is located on one side of the base layer. The light-emitting and reflecting composite layer includes a reflecting layer and a plurality of light-emitting elements. A plurality of receiving holes are formed in the reflecting layer, the light-emitting elements are disposed in the receiving holes, and the light-emitting surface of the light-emitting element faces the base layer; A grating layer, which is located on the other side of the base layer. The grating layer includes a plurality of pixel-type metal grating units, and the pixel-type metal grating units are arranged in one-to-one correspondence with the receiving holes; The design method of the grating layer is as follows: Measure the distances between each point on the pixel-type metal grating unit and the corresponding light-emitting element of the pixel-type metal grating unit to obtain a data set of distances; according to the data set of distances and the light intensity of the light-emitting element at the pixel-type metal grating unit, calculate the total transmittance of the TM polarized light so that the light rays at each point on the metal grating unit are uniformly emitted; The data set of the distance, the light intensity of the light-emitting element at the pixelated metal grating unit, and the total transmittance of the light homogenizing film for TM polarized light satisfy: where I is the light intensity of the light-emitting element at a preset point in the pixelated metal grating unit, T is the total transmittance of a preset point on the light homogenizing film for TM polarized light, a is the distance from the light-emitting element to the preset point in the pixelated metal grating unit, and m is a constant value; The total transmittance T of a preset point on the light homogenizing film for TM polarized light satisfies: Wherein, T0 is the transmittance of the pixel-type metal grating unit for TM polarized light, R0 is the reflectance of the pixel-type metal grating unit for TM polarized light, α is the reflectance of the reflecting layer for reflecting the TM polarized light that has not passed through the pixel-type metal grating unit, and β is the reflectance of converting the TE polarized light reflected by the pixel-type metal grating unit into TM polarized light.

2. The light homogenizing film applied to the mini-LED array light source according to claim 1, characterized in that, The light transmittance of the pixel-type metal grating unit gradually increases from the middle to the periphery, and the middle part of the pixel-type metal grating unit is a profiling structure of the light-emitting element.

3. The light homogenizing film applied to the mini-LED array light source according to claim 1, wherein The light-emitting element is an LED chip.

4. The light homogenizing film applied to the mini-LED array light source according to claim 1, wherein, The plurality of light-emitting elements are arranged in an array.

5. The light homogenizing film applied to the mini-LED array light source according to claim 1, wherein The pixel-type metal grating unit is a one-dimensional double-layer metal grating or a one-dimensional single-layer metal grating.

6. The light homogenizing film applied to the mini-LED array light source according to claim 5, wherein The period of the pixel-type metal grating unit is less than 200 nm.

7. The light homogenizing film applied to the mini-LED array light source according to claim 1, wherein The pixel-type metal grating unit includes a flexible substrate and a dielectric grating and a first metal layer disposed on the flexible substrate. The first metal layer and the dielectric grating are alternately arranged, and a second metal layer is disposed on the upper surface of the dielectric grating.

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