Backlight module and display device

Abstract

This invention provides a backlight module and a display device, belonging to the field of display technology. The backlight module of this invention includes a substrate and a film layer. Light-emitting units are arranged in an array on the substrate; the film layer is disposed on the side of the light-emitting units away from the substrate, and a light-diffusing pattern is disposed on the film layer, the light-diffusing pattern being opposite to the light-emitting units; furthermore, the light-diffusing pattern overlaps with the projection of the emitted light beam from the light-emitting units onto the film layer, and the light-diffusing pattern includes multiple reflective units. This backlight module effectively improves the light emission uniformity of the backlight module without increasing the film layer thickness, achieving high uniformity light emission at low mixing distances and large aspect ratios.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more specifically to a backlight module and a display device. Background Technology

[0002] In light-emitting panels, such as the screens of various electronic products, they are composed of a plurality of tiny light-emitting devices, such as light-emitting diode arrays. When there are enough light-emitting devices, the light emitted by a single point of light source can be combined to form a complete picture and form image content. In order to prevent the light emitted by each light-emitting device from being too concentrated, resulting in too obvious differences in the brightness of the final image, and the appearance of light spots or halos, light mixing is required in the panel.

[0003] Currently, liquid crystal displays (LCDs) have become the mainstream flat panel display technology. Since liquid crystals do not emit light, they require backlighting to provide illumination. The brightness, color gamut, and size of the backlight module largely determine the performance of the final display. The trend towards thinner display products necessitates minimizing the thickness of the backlight module.

[0004] However, existing direct-lit LED backlight modules typically employ secondary lenses for light mixing to reduce the optical distance (OD). But for ultra-thin backlight modules (e.g., OD less than 3mm) and applications with a large distance-to-height ratio (DHR), secondary lenses struggle to meet uniformity requirements at relatively small mixing distances. Currently, the diffusion films used in backlight modules are primarily based on diffuser particles; for ultra-thin backlight modules, it is difficult to form a uniform illumination source at a small mixing distance.

[0005] Therefore, it is necessary to design a backlight module and display device to increase the uniformity of light output in a backlight module with low mixing distance and large distance-to-height ratio, in order to solve the above problems. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention provides a backlight module and a display device to solve the technical problem of poor light emission uniformity of existing backlight module structures under low mixing distance and large distance-to-height ratio.

[0007] To achieve the above and other related objectives, the present invention provides a backlight module comprising a substrate and a film layer.

[0008] The substrate has an array of light-emitting units arranged on it; a film layer is disposed on the side of the light-emitting units away from the substrate, and a light-diffusing pattern is disposed on the film layer, which is disposed opposite to the light-emitting units; and the light-diffusing pattern overlaps with the projection of the emitted light beam of the light-emitting units onto the film layer, and the light-diffusing pattern includes multiple reflective units.

[0009] In one example of the present invention, the uniform light pattern is divided into N concentric regions around the center of the projection, and the light flux of the emitted light beam projected onto each of the concentric regions is equal.

[0010] In one example of the present invention, each concentric region includes a plurality of reflective units, wherein the film layer defines a predetermined region of a non-uniform light pattern around the uniform light pattern, and each concentric region R i The density p of the reflective units arranged in the middle i Based on the average illuminance E of the emitted light beam transmitted through the preset area 非 It is determined that the density p i Let N be the area ratio of the multiple reflective units in the i-th concentric region, and 1≤i≤N.

[0011] In one example of the present invention, the plurality of reflective units are arranged according to the corresponding density p. i They are randomly distributed within the corresponding concentric regions or distributed around the projection center.

[0012] In one example of the present invention, the number of concentric regions in the uniform light pattern is 10 to 30.

[0013] In one example of the present invention, the outer diameter of the reflective unit is 10–30 μm.

[0014] In one example of the present invention, the outer diameter of the reflective unit is 15 μm.

[0015] In one example of the present invention, the reflective unit is triangular, rectangular, hexagonal, or circular in shape.

[0016] In one example of the present invention, the material of the film layer is glass or plexiglass.

[0017] The present invention also provides a display device, the display device including a display panel and a backlight module as described in any of the above examples, the display panel being disposed on the side of the film layer opposite to the light-emitting unit.

[0018] The backlight module of this invention has a uniform light pattern on the film layer on the light-emitting side. The uniform light pattern is correspondingly arranged with the light-emitting units on the substrate and coincides with the projection of the light beam emitted by the light-emitting units onto the film layer. The uniform light pattern adjusts its transmittance in each concentric region around the projection center through multiple reflective units, so that the illuminance emitted by the emitted light beam through each concentric region tends to be uniform. This improves the uniformity of light emission from the backlight module without increasing the film layer thickness, thereby achieving high uniformity light emission from the backlight module under low mixing distance and large aspect ratio. Therefore, this invention effectively overcomes some practical problems in the prior art and has high utilization value and application significance. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a graph showing the emission curve of a single light source in a backlight module without the addition of a film layer in the existing technology.

[0021] Figure 2 This is a schematic cross-sectional view of the backlight module in this invention;

[0022] Figure 3 This is a schematic diagram of the partitioning of the uniform light pattern in this invention;

[0023] Figure 4 This is a schematic diagram of the uniform light pattern in this invention;

[0024] Figure 5 This is a simulated illuminance diagram of the emitted light from the backlight module in one embodiment of the present invention.

[0025] Component designation explanation

[0026] 100, Substrate; 110, Light-emitting unit; 200, Film layer; 210, Light-diffusing pattern; 211, Reflective unit. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0028] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as part of the scope of the invention.

[0029] like Figure 1 As shown, the inventors have discovered through research that in the backlight modules of the prior art, the illuminance distribution emitted from the light-emitting unit 110 without modulation conforms to the Lambertian distribution, and the emitted illuminance gradually decreases from the center to the edge. This light emission method causes the technical problem of low light emission uniformity of the backlight module.

[0030] To address the aforementioned issues without increasing the thickness of the backlight module, this invention provides a backlight module that can achieve uniform light output even with a large aspect ratio, thereby effectively reducing the thickness of the backlight module.

[0031] like Figure 2 As shown, the backlight module includes a substrate 100 and a film layer 200. Light-emitting units 110 are arrayed on the substrate 100, and each light-emitting unit 110 generates an emitted light beam toward the side facing away from the substrate 100. The film layer 200 is disposed opposite to the substrate 100, located on the side of the light-emitting units 110 facing away from the substrate 100, with the film layer 200 facing the light-emitting side of the light-emitting units 110. The emitted light beam generated by the light-emitting units 110 is projected onto the light-incident surface of the film layer 200 and passes through the film layer 200 before exiting from its light-emitting surface.

[0032] The film layer 200 has multiple uniform light patterns 210 disposed on the side of the film layer 200 away from the light-emitting unit 110. Each uniform light pattern 210 is positioned opposite to the light-emitting unit 110, and the uniform light pattern 210 overlaps with the projection of the light beam emitted from the light-emitting unit 110 onto the film layer 200, so as to cover the light spot projected onto the film layer 200 by the corresponding light-emitting unit 110 as much as possible. The uniform light pattern 210 includes multiple reflective units 211, which can adjust the transmittance distribution of the film layer 200 in the area where the uniform light pattern 210 is located, so that the illuminance value in each propagation angle direction after the light beam emitted from the light-emitting unit 110 passes through the film layer 200 tends to be consistent, thereby improving the light emission uniformity of the backlight module without increasing the thickness of the backlight module.

[0033] Considering that the light emitted from the light-emitting unit 110 at different angles contains different energies, the homogenization image performs corresponding zone modulation on the light rays at different transmission angles in the outgoing beam. Specifically, as shown... Figure 3 and Figure 4 As shown, the uniform light pattern 210 is divided into N concentric regions around the center of the projection of the emitted light beam onto the film layer 200, and each concentric region is configured to receive the same luminous flux of the emitted light beam projection. In addition to receiving the same luminous flux, each concentric region includes multiple reflective units 211. These reflective units 211 can adjust the transmittance of their respective concentric regions, thereby modulating the illuminance of the emitted light beam passing through the concentric regions of the cover.

[0034] For the uniform light pattern 210 as a whole, the intensity distribution characteristics of the light beam emitted from the light-emitting unit 110 can be used to calculate the R of each concentric region of the uniform light pattern 210 according to the partitioning. i The average illuminance of the transmitted beam is used to determine the average illuminance of each concentric region R. i The required reflective unit density p is 211 i (i = 1, 2, 3…N), density p i For multiple reflective units 211 relative to their respective concentric regions R i The area percentage.

[0035] Among them, in each concentric region R i According to the corresponding density p i After setting the reflector unit 211, the illuminance of the emitted beam after passing through the film layer 200 where the uniform light pattern 210 is located tends to be uniform, effectively ensuring the uniformity of light output of the backlight module at a small mixing distance. The idea of ​​regional design based on the light emission curve proposed in this invention can be used for the design of other light sources. It can control the light emitted by the light source according to the actual needs. This method has a good light control effect, a wide range of applications, and high promotion value.

[0036] In some embodiments, for a uniform light pattern 210, a preset region of the non-uniform light pattern 210 can be first defined around the outer side of the uniform light pattern 210, and then the average illuminance E of the transmitted light beam in the preset region can be used as the basis for the calculation. 非 To calculate and determine each concentric region R in the uniform light pattern 210 i The transmittance T to be modulated in the film layer 200 i And further determine each concentric region R i The density p of the reflective unit 211 is i So that each concentric region R i Illuminance and average illuminance E of the transmitted beam 非 Towards consensus.

[0037] like Figure 3 and Figure 4 As shown, in the uniform light pattern 210, each concentric region R i (i = 1, 2, 3…N) Transmittance T after modulation by multiple reflective units 211 i Conformity And T i =T 基 -p i (T 基 -T 反 According to the preset average illuminance E 非 The above relationships allow us to obtain the concentric regions R. iThe density p of the reflective units 211 arranged in the middle i Where φ is the concentric region R i Luminous flux, S i For concentric regions R i area, density p i For concentric regions R i The area ratio of multiple reflective units 211 in the middle, T 基 T represents the transmittance of the film layer 200. 反 The transmittance of reflective unit 211.

[0038] The specific process of the above derivation is as follows:

[0039] For the region where the uniform light pattern 210 is located on the film layer 200, the total luminous flux projected by the light-emitting unit 110 onto the uniform light pattern 210 is φ. 总 Total luminous flux φ 总 The effective transmission angle range (0-θ) of the emitted beam's emission curve and the projection of the emitted beam onto the film layer 200 can be combined. 总 The integral is obtained by performing an integral calculation, where θ 总 Based on the backlight module structure, the specific calculation is shown in equation (1):

[0040]

[0041] Wherein, OD is the light mixing distance between substrate 100 and film layer 200, D light D is the light emission aperture of the light-emitting unit 110. max The outer diameter of the uniform light pattern 210;

[0042] The effective transmission angle range (0-θ) of obtaining the projection of the emitted beam onto the film layer 200 is obtained. 总 After that, the total luminous flux φ can be obtained based on equation (2). 总 Equation (2) is shown below:

[0043]

[0044] Where I0 is the light intensity at a transmission angle of 0° in the emission curve.

[0045] like Figure 3 As shown, in the uniform light pattern 210, the total luminous flux φ 总 Divide into N concentric regions R i (i = 1, 2, 3…N), each concentric region R i With the same luminous flux φ, the total luminous flux φ 总 The concentric regions R are obtained by dividing the area equally into partitions. i The luminous flux φ is used to calculate the transmission angle range (θ) of the emitted beam received in the i-th concentric region.i-1 -θ i ), where the luminous flux φ can be expressed by equation (3), and the concentric region R i Maximum transmission angle θ i It can be calculated according to equation (4). Equations (3) and (4) are shown below:

[0046]

[0047]

[0048] Then, based on each concentric region R i The transmission angle range of the received outgoing beam (θ) i-1 -θ i ), calculate the concentric region R according to equation (5) i The outer diameter D on the membrane layer 200 i And further calculate the concentric region R according to equation (6). i area S i Equations (5) and (6) are shown below:

[0049] D i = (2×OD×tanθ) i )+D light (5)

[0050]

[0051] Furthermore, a predetermined region without a uniform light pattern 210 is pre-defined in the film layer 200, and the outer diameter D of this predetermined region is... 非 The distance between the light-emitting units 110 and the substrate 100 is less than or equal to the spacing P, and greater than or equal to the outer diameter D of the uniform light pattern 210. max The average illuminance E of the transmitted beam in the preset area is calculated. 非 This allows for the application of light to each concentric region R in the uniform light pattern 210. i Modulated transmittance T i Target identification; furthermore, the more light the emitted beam can be covered by the preset illuminance, the higher the average illuminance E. 非 The higher the reliability, the better the fitting calculation is performed using the upper limit value of the outer diameter of the preset region.

[0052] The average illuminance E of the transmitted beam in the preset area 非 The equations (7), (8), (9), and (10) are derived sequentially and are shown below:

[0053]

[0054]

[0055]

[0056]

[0057] Where, θ 非 φ 非 S 非 These are the maximum transmission angle, luminous flux, and area of ​​the emitted beam covered by the preset region, respectively.

[0058] In obtaining the average illuminance E 非 Then, based on the principle of illuminance averaging, the R values ​​of each concentric region in the uniform light pattern 210 are calculated. i Transmittance T i The calculation process is shown in equation (11):

[0059]

[0060] Then, based on each concentric region R i Required modulated transmittance T i The concentric region R is determined according to equation (12). i The area A of the reflective unit 211 to be installed i Equation (12) is shown below:

[0061]

[0062] Among them, T 基 T represents the transmittance of the film layer 200. 反 T represents the transmittance of reflective unit 211. 基 and T 反 The known parameters of the backlight module;

[0063] Based on each concentric region R i The area A of the reflective unit 211 arranged in the middle i Obtain each concentric region R i The density p of the reflective units 211 arranged in the middle i The calculation process is shown in equation (13):

[0064]

[0065] Finally, according to each concentric region R i The density p of the reflective units 211 arranged in the middle i The reflective unit 211 is attached to the surface of the film layer 200 through a printing process to form the desired uniform light pattern 210.

[0066] Furthermore, in some embodiments, the backlight module of the present invention can reduce the light mixing distance between the film layer 200 and the light-emitting unit 110 in the backlight module to less than 3 mm, while ensuring that its own light emission uniformity is higher than 80%.

[0067] In some embodiments, each reflective unit 211 may be made of a white reflective medium, and the shape of the reflective unit 211 may be unrestricted, for example, it may be a triangle, rectangle, hexagon or circle. Preferably, the shape of the reflective unit 211 may be a circle.

[0068] In some embodiments, the number of concentric regions in the uniform light pattern 210 is 10 to 30. The more equal luminous flux partitions there are in the uniform light pattern 210, the more precise the control of the emitted beam, and the better the uniformity of the final output energy. When the number of partitions increases to 20, the improvement effect on the uniformity of the backlight module output light is very weak, but the processing difficulty increases significantly. Therefore, in one example, the number of concentric regions in the uniform light pattern 210 is preferably 20.

[0069] In some embodiments, the outer diameter of the reflective unit 211 disposed on the film layer 200 is 10-30 μm. For example, the outer diameter of the reflective unit 211 can be 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, 23 μm, 25 μm, 27 μm, or 30 μm. The larger the size of the reflective unit 211 in the uniform light pattern 210, the worse the light emission uniformity of the backlight module. Considering the influence of processing difficulty, the size of a single reflective unit 211 should not be too small. Therefore, in one example, the outer diameter of the reflective unit 211 is preferably 15 μm, which can balance the light emission uniformity of the backlight module and processing convenience.

[0070] In some embodiments, the substrate 100 material is glass or plexiglass. In one example, the substrate 100 material is plexiglass, such as polymethyl methacrylate, polyethylene terephthalate, polycarbonate (PC) or polyethylene terephthalate (PET), preferably polymethyl methacrylate.

[0071] It should be noted that in the backlight module, the light-emitting unit 110 can be any integrable light source. For example, in some embodiments, the light-emitting unit 110 can be an LED.

[0072] Furthermore, in some embodiments, the present invention also provides a display device, which includes a display panel and a backlight module as described in any of the above embodiments. The display panel is disposed on the side of the film layer 200 opposite to the light-emitting unit 110. The shape and size of the display panel are generally matched with the backlight module. Typically, the display panel can be rectangular or circular. The display panel can be a liquid crystal display panel, capable of modulating the transmittance of light, but it does not emit light itself. The display panel has multiple pixel units arranged in an array, and each pixel unit can independently control the transmittance and color of the light incident from the backlight module onto the pixel unit, so that the light transmitted through all pixel units constitutes the displayed image.

[0073] The following specific embodiments compare the display results of the technical solution of the present invention with those of the holographic waveguide display device in the prior art.

[0074] Example 1

[0075] This embodiment provides a backlight module. In the backlight module, multiple light-emitting units are arrayed on the substrate. The light-emitting units are LED chips. The spacing between adjacent LEDs is 9mm. The length of the LED is 0.711mm, the width is 0.254mm, and the height is 0.15mm. The LED emits a Lambertian light. The mixing distance between the film layer and the LED light source is 3mm. The film layer includes a light-uniforming pattern corresponding to the LED. The outer diameter of the light-uniforming pattern is set to 8mm. The light-uniforming pattern includes multiple reflective units. The transmittance of the film layer is 90%, the reflectance is 2%, and the absorptivity is 8%. The transmittance of the reflective units is 17%, the reflectance is 73%, and the absorptivity is 10%. The pattern presented by the reflective units on the surface of the film layer is a circle with a diameter of 15μm.

[0076] The reflective units in the uniform light pattern are arranged as follows: First, the uniform light pattern is divided into 20 concentric regions R around the projection center of the emitted beam. i Simultaneously, a pre-defined annular region for a non-uniform light pattern is divided outside the uniform light pattern with a maximum outer diameter of 9mm; based on the emission curve of the LED emitted beam, the average illuminance E of the emitted beam received in the pre-defined region is calculated. 非 And combined with average illuminance E 非 Calculate the R values ​​of each concentric region in the uniform light pattern. i Modulated transmittance T i Then, based on each concentric region R i Required modulated transmittance T i The reflection unit in each concentric region R is calculated. i Required arrangement density p i And the quantity.

[0077] like Figure 5As shown, the backlight module proposed in this embodiment achieves good light emission uniformity with a mixing distance of only 3mm, reaching 83.2%. In contrast, backlight modules using traditional diffuser films require a minimum mixing distance of 8mm to achieve the same light emission uniformity while maintaining the same LED spacing. By reducing the mixing distance to 3mm in this embodiment, the thickness of the backlight module is significantly reduced, achieving the desired thinning effect.

[0078] The backlight module of this invention has a uniform light pattern on the film layer on the light-emitting side. The uniform light pattern is correspondingly arranged with the light-emitting units on the substrate and coincides with the projection of the light beam emitted by the light-emitting units onto the film layer. The uniform light pattern adjusts its transmittance in each concentric region around the projection center through multiple reflective units, so that the illuminance emitted by the emitted light beam through each concentric region tends to be uniform. This improves the uniformity of light emission from the backlight module without increasing the film layer thickness, thereby achieving high uniformity light emission from the backlight module under low mixing distance and large aspect ratio. Therefore, this invention effectively overcomes some practical problems in the prior art and has high utilization value and application significance.

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A backlight module, characterized in that, include: A substrate on which light-emitting units are arranged in an array; A film layer is disposed on the side of the light-emitting unit away from the substrate, and a light-diffusing pattern is disposed on the film layer, the light-diffusing pattern being disposed opposite to the light-emitting unit; The uniform light pattern overlaps with the projection of the emitted light beam from the light-emitting unit onto the film layer, and the uniform light pattern includes multiple reflective units. The uniform light pattern is divided into N concentric regions around the center of the projection. The light flux of the emitted beam projected onto each of the concentric regions is equal. Each concentric region includes multiple reflective units. The film layer defines a preset region of non-uniform light pattern around the uniform light pattern. Each of the concentric regions R i The density of the reflective units arranged in the middle Based on the average illuminance of the emitted light beam transmitted through the preset area Determined, the density Let N be the area ratio of the multiple reflective units in the i-th concentric region, and 1≤i≤N; The density The following relationship must be satisfied: ， ， in, The luminous flux of the concentric region, Let i be the area of ​​the i-th concentric region. The transmittance of the film layer is... The transmittance of the reflective unit is given by [reference to a specific unit]. The transmittance of the film layer corresponding to the i-th concentric region after the reflective unit is set is denoted as i.

2. The backlight module according to claim 1, characterized in that, The plurality of reflective units are arranged according to the corresponding density They are randomly distributed within the corresponding concentric regions or distributed around the projection center.

3. The backlight module according to claim 1, characterized in that, The number of concentric regions in the uniform light pattern is 10 to 30.

4. The backlight module according to claim 1, characterized in that, The outer diameter of the reflective unit is 10~30μm.

5. The backlight module according to claim 4, characterized in that, The outer diameter of the reflective unit is 15 μm.

6. The backlight module according to claim 1, characterized in that, The reflective unit can be triangular, rectangular, hexagonal, or circular in shape.

7. The backlight module according to claim 1, characterized in that, The material of the film layer is glass or plexiglass.

8. A display device, characterized in that, The display device includes a display panel and a backlight module according to any one of claims 1 to 7, wherein the display panel is disposed on the side of the film layer opposite to the light-emitting unit.

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