Backlight module, display and preparation method

Abstract

Disclosed in the application is a backlight module, a display and a preparation method. The backlight module comprises a back plate, a lamp plate arranged on one side of the back plate, the lamp plate being provided with at least two kinds of light emitting chips of different colors, and a micro-prism film arranged on the side of the lamp plate away from the back plate, the micro-prism film comprising at least two micro-prism units, each micro-prism unit corresponding to one light emitting chip, each micro-prism unit comprising a micro-prism body and a dielectric film arranged on the micro-prism body. The micro-prism body is used for refracting and deflecting the first light emitted by the light emitting chip of the corresponding color to a corresponding target angle to obtain second light. The dielectric film is used for transmitting the second light of the corresponding color to obtain a backlight light source. The application can still maintain uniform white balance under a large viewing angle, effectively eliminates color deviation phenomenon, and improves display quality.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a backlight module, a display, and a method for manufacturing them. Background Technology

[0002] In recent years, RGB Mini Light Emitting Diode (LED) backlight technology has gradually emerged. This technology directly uses red (R), green (G), and blue (B) Mini LED chips as backlights, which can not only provide purer colors and achieve extremely high color gamut coverage, but also have better environmental stability and longer service life.

[0003] However, in practical applications, due to the different emission wavelengths of the red, green, and blue light-emitting chips (for example, the center wavelength of the red chip is approximately 625nm, the green chip is approximately 525nm, and the blue chip is approximately 450nm), the refractive index and propagation characteristics of light of different wavelengths in the same optical medium material vary significantly, resulting in inconsistent propagation behavior of the three colors of light in the backlight module. Specifically, when RGB light passes through optical layers such as the homogenizing layer and prism film in the backlight module, the spatial distribution of the three colors of light is difficult to maintain consistently due to the different refraction, reflection, and scattering paths experienced by each color. Especially at wide viewing angles, this difference is further amplified, leading to obvious color shift. That is, when observing the display from different angles, the perceived white balance and color performance are significantly different, seriously affecting the display quality. Summary of the Invention

[0004] The main objective of this application is to provide a backlight module, a display, and a manufacturing method, aiming to solve the technical problem in the prior art where the refractive index and propagation characteristics of light of different wavelengths in the same optical medium material are significantly different, resulting in inconsistent propagation behavior of the three colors of light in the backlight module, which affects the display quality.

[0005] To achieve the above objectives, this application proposes a backlight module, the backlight module comprising: Back panel; A light panel is disposed on one side of the back panel, and at least two different colors of light-emitting chips are arranged on the light panel; A microprism film is disposed on the side of the lamp panel away from the back plate, and includes at least two microprism units. Each microprism unit corresponds to one of the light-emitting chips. Each microprism unit includes a microprism body and a dielectric film disposed on the microprism body. The microprism body is used to refract and deflect the first light emitted by the light-emitting chip of the corresponding color to the corresponding target angle to obtain the second light. The dielectric film is used to transmit the second light of the corresponding color to obtain a backlight source.

[0006] In one embodiment, the cross-section of the microprism body is triangular.

[0007] In one embodiment, the microprism body has a light-incident surface facing the lamp panel and two light-exit surfaces facing away from the lamp panel. The two light-exit surfaces are respectively the two legs of the triangle, and the included angle between the two light-exit surfaces forms the vertex angle of the triangle. The triangle is an isosceles triangle, and the vertex angle of the microprism body corresponding to a specific color is... ;

[0008] in, The center wavelength of the first light ray corresponding to the color of the microprism body. The microprism body at its center wavelength is The refractive index at that point, The target angle of the first ray of the corresponding color.

[0009] In one embodiment, the dielectric film includes a plurality of first material layers and a plurality of second material layers, wherein the refractive index of the first material layers is higher than that of the second material layers; The first material layer and the second material layer are alternately stacked.

[0010] In one embodiment, each of the microprism units further includes a gradient layer; The gradient layer is disposed on the side of the dielectric film opposite to the microprism body; The gradient layer is used to output a third ray after the second ray of the corresponding color is refracted at least twice between the dielectric film and the air through at least two different equivalent refractive indices. In this process, at least twice the equivalent refractive index gradually changes from the refractive index of the dielectric film to the refractive index of the air.

[0011] In one embodiment, the gradient layer is a grating structure, and the period of the grating structure corresponding to the color is... ;

[0012] in, The period of the grating structure corresponding to the color. This is the subwavelength margin factor. The center wavelength of the second ray corresponding to the color, Let be the refractive index of the air.

[0013] In one embodiment, the depth of the grating structure is hc, and the duty cycle is fc; In the grating structure, the period is When the depth is hc and the duty cycle is fc, the corresponding objective function value is minimized. The objective function is:

[0014] in, The value of the objective function. The incident angle of the first light ray to the corresponding microprism body. The incident angle The corresponding preset viewpoint weight coefficients, The transmittance of the red third ray output by the grating structure. The transmittance of the third green ray output by the grating structure. The transmittance of the blue third ray output by the grating structure. The preset average transmittance weighting coefficient, The average transmittance of the c-th color within the preset evaluation angle range.

[0015] In addition, to achieve the above objectives, this application also provides a display, the display including a display panel, a timing controller and a backlight module as described above, the backlight module being disposed on the back of the display panel, and the timing controller being electrically connected to the backlight module; The timing controller is used to output display signals to the backlight module; The backlight module is used to provide a backlight source to the display panel according to the display signal.

[0016] In one embodiment, the timing controller is further configured to acquire color information of the displayed image and determine the target brightness ratio corresponding to each pixel based on a preset white balance target and the color information, wherein the pixel includes light-emitting chips of at least two different colors; The timing controller is also used to acquire the characteristic curves of each of the light-emitting chips, and to back-calculate the initial driving current that satisfies the target brightness ratio based on each of the characteristic curves. The timing controller is also used to obtain the actual transmittance of the backlight module for each color, and to obtain the corresponding target driving current according to the preset conversion factor, the actual transmittance of each color and the corresponding initial driving current. The timing controller is also used to output a corresponding display signal to the backlight module according to the corresponding target drive current.

[0017] Furthermore, to achieve the above objectives, this application also provides a preparation method for preparing a backlight module as described above, the method comprising: Obtain the back plate and the light panel, and fix the light panel to one side of the back plate; Obtain a substrate and form at least two microprism bodies on one side surface of the substrate; A dielectric film is sequentially deposited on the surface of each microprism body using a mask. The microprism body with the dielectric film deposited is referred to as a microprism unit, and each microprism unit and the substrate are referred to as a microprism film. Each microprism body corresponds to a light-emitting chip. The microprism film is fixed to the side of the lamp panel away from the back panel to obtain the backlight module.

[0018] This application provides a backlight module, a display, and a manufacturing method. The backlight module includes: a backplate; a lamp plate disposed on one side of the backplate, wherein at least two different colored light-emitting chips are arranged on the lamp plate; a microprism film disposed on the side of the lamp plate away from the backplate, comprising at least two microprism units, each microprism unit corresponding to one light-emitting chip, and each microprism unit comprising a microprism body and a dielectric film disposed on the microprism body; the microprism body is used to refract and deflect a first light emitted by the light-emitting chip of the corresponding color to a corresponding target angle to obtain a second light; the dielectric film is used to transmit the second light of the corresponding color to obtain a backlight source.

[0019] After the backlight module of this application is powered on, the light-emitting chips of each color on the light board emit light of their respective colors, denoted as the first light rays. Then, each color of the first light rays propagates upward and reaches the microprism unit corresponding to the position of the light-emitting chip. Each microprism unit includes a microprism body and a dielectric film disposed on the microprism body. The first light rays first pass through the microprism body. Since different colors of light correspond to different microprism bodies, each microprism body refracts and deflects the first light rays of its corresponding color, so that the light rays change from random propagation to being emitted towards a preset target angle, thus obtaining the second light rays. The second light rays pass through the dielectric film disposed on the microprism body. The dielectric film only allows the second light rays of the corresponding color to pass through, while reflecting or blocking light rays of non-corresponding colors. After the angle deflection of the microprism body and the color selection of the dielectric film, each color of light rays is emitted from its respective microprism unit at its respective target angle, together forming a uniform backlight source. Because this application simultaneously sets up a microprism body for refracting and deflecting light and a dielectric film for selecting the transmission of corresponding color light in each microprism unit, compared with the obvious color shift phenomenon in the existing ones, this application sets up corresponding microprism units for different colors of light. Each microprism unit refracts, deflects and selects the color of its corresponding color light, so that each color light is adjusted to its respective target angle before emission, thereby making the spatial distribution of each color light more consistent, maintaining uniform white balance even at a large viewing angle, effectively eliminating the color shift phenomenon and improving display quality. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the first embodiment of the backlight module of this application; Figure 2 This is a schematic diagram of the dielectric film structure in the first embodiment of the backlight module of this application; Figure 3 This is a distribution map of the concentration of scattering particles in the homogenizing layer. Figure 4 This is a schematic diagram of the microprism bodies corresponding to different apex angles in the second embodiment of the backlight module of this application; Figure 5 Optimize the reflectance / transmittance curve of the dielectric film for red light; Figure 6 A comparison chart of color shift values ​​between differentiated vertex angle schemes and unified vertex angle schemes; Figure 7 A comparison chart of optical distances between the differentiated apex angle scheme and the unified apex angle scheme; Figure 8 This is a schematic diagram of the gradient layer structure in the third embodiment of the backlight module of this application; Figure 9 The simulated transmittance curves of the grating structure at different incident angles are shown. Figure 10 A curve for comparing color uniformity tests; Figure 11 This is a schematic flowchart of the first embodiment of the preparation method of this application.

[0023] Explanation of icon numbers: 1. Backplate; 2. Lamp panel; 21. Light-emitting chip; 3. Microprism film; 31. Microprism unit; 311. Microprism body; 312. Dielectric film; 313. Gradient layer; 32. Substrate; 4. Light-diffusing layer; 5. Diffuser plate; 6. Liquid crystal display panel.

[0024] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0028] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0029] Understandably, in recent years, RGB Mini LED backlighting technology has gradually emerged. This technology directly uses red (R), green (G), and blue (B) Mini LED backlight chips as the backlight source, which not only provides purer colors and achieves extremely high color gamut coverage, but also has better environmental stability and a longer lifespan.

[0030] However, in practical applications, due to the different emission wavelengths of the red, green, and blue light-emitting chips 21 (for example, the center wavelength of the red light-emitting chip 21 is approximately 625nm, the center wavelength of the green light-emitting chip 21 is approximately 525nm, and the center wavelength of the blue light-emitting chip 21 is approximately 450nm), the refractive index and propagation characteristics of light of different wavelengths in the same optical medium material are significantly different, resulting in inconsistent propagation behavior of the three colors of light in the backlight module. Specifically, when the RGB three-color light passes through the light-diffusing layer 4, prism film, and other optical films in the backlight module, due to the different refraction, reflection, and scattering paths experienced by each color of light, the spatial distribution of the three colors of light is difficult to maintain in a consistent manner. Especially at large viewing angles, this difference is further amplified, leading to obvious color shift. That is, when observing the display screen from different angles, the perceived white balance and color performance are significantly different, seriously affecting the display quality.

[0031] Therefore, in order to solve the above-mentioned defects, this embodiment provides a backlight module. Since this embodiment simultaneously sets up a microprism body 311 for refracting and deflecting light and a dielectric film 312 for selecting the transmission of corresponding color light in each microprism unit 31, compared with the obvious color shift phenomenon in the existing ones, this application sets up corresponding microprism units 31 for different colors of light. Each microprism unit 31 refracts, deflects and selects the color of its corresponding color light, so that each color light is adjusted to its respective target angle before emission, so that the spatial distribution of each color light tends to be consistent, and uniform white balance can still be maintained at a large viewing angle, effectively eliminating the color shift phenomenon and improving the display quality.

[0032] For ease of understanding, the following is combined with Figures 1 to 11 The backlight module provided in the embodiments of this application will be described in detail.

[0033] Reference Figure 1 , Figure 1 This is a structural schematic diagram of the first embodiment of the backlight module of this application. Figure 1 As shown, in this embodiment, the backlight module includes: Back panel 1; The light panel 2 is disposed on one side of the back plate 1, and at least two different colors of light-emitting chips 21 are arranged on the light panel 2.

[0034] It should be noted that the aforementioned backplate 1 can be a base plate structure in the backlight module used to support and carry other components, and can be made of metal materials (such as aluminum, stainless steel) or composite materials, etc. This embodiment does not limit this. Furthermore, the surface of the aforementioned backplate 1 facing the lamp panel 2 can be set as a reflective surface, which can be used to reflect downward-propagating light back upward to improve light energy utilization.

[0035] It should also be noted that the aforementioned lamp board 2 can be a circuit board with an array of light-emitting chips 21, which can be used to provide electrical connections and mechanical support for the light-emitting chips 21. It can be a printed circuit board or a flexible circuit board, etc., and this embodiment does not limit this. In this embodiment, as... Figure 1 As shown, the light panel 2 can be provided with at least two different colored light-emitting chips 21. In this embodiment, it can include a red light-emitting chip 21 (i.e., Figure 1 (R), green light-emitting chip 21 (i.e.) Figure 1 (G) and blue light-emitting chip 21 (i.e. Figure 1 (See section B). The center wavelength of the red light-emitting chip 21 can be 625nm, the center wavelength of the green light-emitting chip 21 can be 525nm, and the center wavelength of the blue light-emitting chip 21 can be 450nm. The light-emitting chips 21 can be arranged alternately in an RGBRGB order, with a chip spacing of 0.5mm to 2mm and a chip size of 100μm to 200μm. Of course, other arrangements, spacings, and sizes are also possible, but this embodiment does not impose any limitations on these.

[0036] Furthermore, in order to reduce color cast, continue as follows Figure 1 As shown, and refer to Figure 2 , Figure 2 This is a schematic diagram of the dielectric film 312 in the first embodiment of the backlight module of this application. In this embodiment, the backlight module further includes: The microprism film 3 is disposed on the side of the lamp plate 2 away from the back plate 1, and includes at least two microprism units 31. Each microprism unit 31 corresponds to one light-emitting chip 21. Each microprism unit 31 includes a microprism body 311 and a dielectric film 312 disposed on the microprism body 311. The microprism body 311 is used to refract and deflect the first light emitted by the light-emitting chip 21 of the corresponding color to the corresponding target angle to obtain the second light. The dielectric film 312 is used to transmit the second light of the corresponding color to obtain a backlight source.

[0037] Understandably, the aforementioned microprism film 3 can be an optical film with a micron-scale prism structure, which can be used to refract and control incident light to change the direction of light propagation. The aforementioned microprism unit 31 can be a basic optical structure unit in the microprism film 3 corresponding to the position of a single light-emitting chip 21, and each microprism unit 31 independently performs optical control on the light from the corresponding light-emitting chip 21.

[0038] It is also understandable that, such as Figure 2 As shown, the microprism body 311 can refer to the transparent optical structure that constitutes the main body of the microprism unit 31, having at least one light-incident surface and at least two light-outceasing surfaces. The two light-outceasing surfaces intersect to form a vertex. The first light emitted by the light-emitting chip 21 is refracted inside and on the surface of the microprism body 311, thereby changing the propagation direction.

[0039] It should be understood that the aforementioned dielectric film 312 can be an optical thin film layer disposed on the surface of the microprism body 311, which can be used to selectively transmit or reflect received light based on the wavelength of the light. The aforementioned first light can refer to the original light emitted by the light-emitting chip 21, and the spatial propagation direction of the aforementioned first light has not yet been controlled by the microprism body 311. The aforementioned second light can be light that has been refracted and deflected by the microprism body 311, and the propagation direction of the aforementioned second light has been adjusted to the target angle. The aforementioned backlight source can be uniform light emitted from the microprism film 3 to provide illumination for the display panel.

[0040] It should also be understood that the aforementioned target angle can be the deflection angle of the emitted light relative to the normal direction, predetermined according to design requirements. For example, it can be an angle value that makes the spatial distribution of different colored light rays tend to be uniform after emission. In this embodiment, the target angles for different colors may be different, and can be set according to the actual situation. This embodiment does not impose any restrictions on this.

[0041] It should be emphasized that the aforementioned dielectric film 312 can be disposed on the light-incident surface side of the microprism body 311 (i.e., the side of the microprism body closest to the lamp plate 2), or on the light-exiting surface side (i.e., the side of the microprism body furthest from the lamp plate 2), or simultaneously on both the light-incident and light-exit surfaces, such as... Figure 2 As shown, this embodiment uses a dielectric film 312 disposed on the light-emitting surface side for explanation and illustration, but does not impose specific limitations on this embodiment. Furthermore, since the microprism body 311 has two light-emitting surfaces, the aforementioned dielectric film 312 can be disposed on both light-emitting surfaces.

[0042] In a specific implementation, the backlight module, from bottom to top, may include a backplate 1, a lamp plate 2, and a microprism film 3. The backplate 1 is located at the bottom of the entire backlight module. The lamp plate 2 is located on the surface of the backplate 1 facing the microprism film 3. Multiple light-emitting chips 21 are arranged on the lamp plate 2, including at least two different color types, such as red, green, and blue light-emitting chips 21. The microprism film 3 is located on the side of the lamp plate 2 facing away from the backplate 1, i.e., above the lamp plate 2. The microprism film 3 may include a microprism array, which may include multiple microprism units 31. The number of microprism units 31 is at least two, and each microprism unit 31 corresponds to one light-emitting chip 21 in position, i.e., each microprism unit 31 is located in the optical path directly above its corresponding light-emitting chip 21. Each microprism unit 31 may include a microprism body 311 and a dielectric film 312 disposed on the surface of the microprism body 311.

[0043] In the specific implementation, each color light-emitting chip 21 on the light board 2 emits a first light of its own color after being powered on (i.e., Figure 2 The first ray (incident light) propagates upwards and enters the microprism unit 31 corresponding to the position of the light-emitting chip 21. The first ray first passes through the microprism body 311, which refracts and deflects it to a preset target angle according to the wavelength characteristics of its corresponding color, transforming the originally divergent light into a second ray emitted along the target direction. The second ray then immediately reaches the dielectric film 312 disposed on the microprism body 311. The dielectric film 312 filters the second ray based on its spectral selectivity, allowing light of the corresponding color matching the designed wavelength of the dielectric film 312 to pass through (i.e.,...). Figure 2 The backlight source (projected light) is used, while stray light of other colors is reflected or absorbed (i.e.,...). Figure 2(Reflected light). For the second light generated by the microprism body 311 corresponding to the red light-emitting chip 21, the corresponding dielectric film 312 can only allow the red second light to pass through. For the second light generated by the microprism body 311 corresponding to the green light-emitting chip 21, the corresponding dielectric film 312 can only allow the green second light to pass through. For the second light generated by the microprism body 311 corresponding to the blue light-emitting chip 21, the corresponding dielectric film 312 can only allow the blue second light to pass through. The light of each color passing through the dielectric film 312 is mixed and superimposed after being emitted from their respective microprism units 31, forming a uniform backlight source. Since this embodiment independently adjusts the angle and selects the spectrum of different colors of light through the microprism body 311 and the dielectric film 312, the light of each color is adjusted to a consistent target direction before emission and the interference of impurities is filtered out, so that the spatial distribution of the light of each color tends to be uniform.

[0044] Furthermore, continue as Figure 1 As shown, in order to support the microprism unit 31, in this embodiment, the microprism film 3 further includes a substrate 32; The substrate 32 is disposed between the microprism body 311 and the lamp plate 2.

[0045] It should be noted that the substrate 32 can be a transparent support layer for supporting the microprism body 311, such as a flexible film made of polyethylene terephthalate (PET) or a rigid substrate made of glass, etc. This embodiment does not limit this.

[0046] It should also be noted that the substrate 32 can be integrally connected to the microprism body 311 through an imprinting process or through an adhesive layer. This embodiment uses an integral connection through an imprinting process for explanation, but does not impose specific limitations on this embodiment. The substrate 32 and the lamp plate 2 can be separated by an air gap or indirectly connected through a light-diffusing layer 4, and this embodiment does not impose specific limitations.

[0047] In the specific implementation, each color light-emitting chip 21 on the light panel 2 emits a first light of its own color after being powered on. The first light propagates upward and first reaches the substrate 32 of the microprism film 3. Since the substrate 32 is made of transparent material, the first light passes through the substrate 32 and enters the microprism body 311 disposed above the substrate 32. The microprism body 311 refracts and deflects the first light to a preset target angle according to the wavelength characteristics of its corresponding color, thereby obtaining the second light. Since this embodiment uses the substrate 32 to support the microprism body 311, the microprism array can be independently formed into a film and manufactured and assembled separately from the light panel 2, reducing the overall manufacturing difficulty and cost of the backlight module.

[0048] Furthermore, in order to align each microprism body 311 with the corresponding color light-emitting chip 21, in this embodiment, the spacing between adjacent microprism bodies 311 of the same color is consistent with the spacing between adjacent light-emitting chips 21 of the same color.

[0049] It should be understood that the above-mentioned interval may refer to the center distance or edge distance between two adjacent microprism bodies 311 of the same color or between two adjacent light-emitting chips 21 of the same color, for example, the distance from the center of the microprism body 311 corresponding to the first red light-emitting chip 21 to the center of the microprism body 311 corresponding to the adjacent second red light-emitting chip 21.

[0050] In the specific implementation, during the manufacturing process of the backlight module, the spacing between adjacent light-emitting chips 21 of the same color on the lamp board 2 is first determined. Then, based on this spacing, the spacing between corresponding microprism bodies 311 of the same color on the microprism film 3 is designed to ensure that the two are numerically consistent. During assembly, the microprism film 3 is aligned with the lamp board 2, so that each microprism body 311 is aligned vertically with its corresponding color light-emitting chip 21. Since the spacing between adjacent microprism bodies 311 of the same color is consistent with the spacing between adjacent light-emitting chips 21 of the same color, each light-emitting chip 21 can be aligned with its corresponding microprism body 311, reducing cumulative offset. Considering that in actual large-scale production, the microprism film 3 and the lamp board 2 are manufactured separately and then assembled, if their cycles are inconsistent, cumulative alignment errors will occur after assembly, causing some microprism bodies 311 to fail to correspond precisely with the light-emitting chip 21. Therefore, in the above-mentioned design steps of the microprism film 3, the spacing between adjacent microprism bodies 311 of the same color is made consistent with the spacing between adjacent light-emitting chips 21 of the same color. This ensures a one-to-one correspondence between the microprism bodies 311 and the light-emitting chip 21 at the structural design level, reducing the cumulative errors caused by cycle mismatch.

[0051] Because this embodiment keeps the arrangement period of the microprism body 311 consistent with the arrangement period of the light-emitting chip 21, each microprism unit 31 can be precisely aligned with the light-emitting chip 21 of the corresponding color, ensuring that all colors of light can pass through the refraction and deflection of their corresponding microprism body 311 and the spectral selection of the dielectric film 312, thereby improving the optical consistency and yield of the backlight module.

[0052] Furthermore, continue as Figure 1 As shown, in order to improve the overall optical uniformity of the backlight module, the backlight module further includes: a light-diffusing layer 4; The light-diffusing layer 4 is disposed between the substrate 32 and the lamp plate 2, and is used to uniformly distribute the first light rays emitted by the lamp plate 2.

[0053] It is understood that the aforementioned light-uniforming layer 4 can be an optical functional layer used to uniformly distribute light, such as a composite layered structure composed of a transparent resin matrix and scattering particles dispersed therein. This embodiment does not limit this. The scattering particles can be, for example, BaSO4 microspheres with a particle size of 2~5μm, or TiO2 nanoparticles with a particle size of 200~500nm. This embodiment does not limit this, and the concentration distribution of the scattering particles can follow a two-dimensional Gaussian decay function, that is, the concentration is higher in the high-concentration scattering region directly facing each light-emitting chip 21, and the concentration is lower in the low-concentration scattering region between adjacent chips, so as to achieve a preliminary light-uniforming effect.

[0054] Reference Figure 3 , Figure 3 This is a distribution diagram of the scattering particle concentration in homogenizing layer 4. Figure 3 As shown, in the light-diffusing layer 4, the light-emitting chip 21 (i.e. Figure 3 The area directly above the LED (21) is a high-concentration scattering region, where the concentration of scattered particles is relatively high. The area between two adjacent LEDs is a low-concentration region, where the concentration of scattered particles is relatively low, thus following a two-dimensional Gaussian decay function. Figure 3 The diagram shows a two-dimensional Gaussian decay function. The horizontal axis represents the radial distance r in mm, and the vertical axis represents the scattering particle concentration C(r) in wt%.

[0055] according to Figure 3 It is easy to see that the concentration of scattered particles varies with distance from the center of the light-emitting chip 21 (i.e., the two-dimensional Gaussian decay function mentioned above) can be:

[0056] in, Let r be the concentration of scattered particles at a radial distance of r, where r is the radial distance (distance from the center). Preset maximum concentration This is the preset minimum concentration.

[0057] Furthermore, within the range of -15mm to 15mm, r=0mm (i.e., the center position of the LED chip), the concentration is the highest, reaching 25wt%, while the concentration is the lowest, at r=-15mm and 15mm, at 5wt%.

[0058] It is also understood that the light-diffusing layer 4 and the substrate 32 can be bonded together with optical adhesive or directly stacked and contacted. This embodiment uses direct stacking and contacting connection for explanation, but does not impose specific limitations on this embodiment. The light-diffusing layer 4 and the lamp board 2 can be separated by an air gap or bonded together. This embodiment uses air gap separation for explanation, but does not impose specific limitations on this embodiment.

[0059] In the specific implementation, each color light-emitting chip 21 on the lamp board 2 emits a first light of its own color after being powered on. The first light propagates upward and first enters the homogenizing layer 4. The scattering particles in the homogenizing layer 4 can scatter the incident first light, making the spatial distribution of the light tend to be uniform, thus obtaining the first light after homogenization. After homogenization, the first light exits from the homogenizing layer 4 and reaches the substrate 32. After passing through the substrate 32, it enters the microprism body 311 disposed above the substrate 32. Because this embodiment pre-homogenizes the light emitted by the light-emitting chip 21 through the homogenizing layer 4, the light distribution entering the microprism body 311 is more uniform, avoiding the adverse effects of the discrete point light source characteristics of the light-emitting chip 21 on the uniformity of the final emitted light.

[0060] In this embodiment, each microprism unit 31 is simultaneously provided with a microprism body 311 for refracting and deflecting light and a dielectric film 312 for selecting the transmission of light of the corresponding color. Compared with the existing method which has obvious color shift, this application provides corresponding microprism units 31 for different colors of light. Each microprism unit 31 refracts, deflects and selects the color of its corresponding color light, so that each color light is adjusted to its respective target angle before emission. As a result, the spatial distribution of each color light tends to be consistent, and uniform white balance can still be maintained at a large viewing angle, effectively eliminating the color shift phenomenon and improving the display quality.

[0061] Continue to refer to Figure 2 Based on the first embodiment described above, a second embodiment of this application is proposed.

[0062] In this embodiment, in order to refract and deflect first rays of different colors to the corresponding target angle, the cross-section of the microprism body 311 is triangular.

[0063] It should be noted that the aforementioned cross-section can be a two-dimensional geometric shape obtained by cutting the microprism body 311 along a plane perpendicular to its length or perpendicular to the plane of the base 32. The aforementioned triangle can be a geometric figure with three vertices and three sides, such as an isosceles triangle, etc., and this embodiment does not limit this. Furthermore, on the same light-emitting chip 21 that is all of the same color, the aforementioned microprism body 311 can be a whole cone, or a square pyramid can be set separately for each light-emitting chip 21, etc., and this embodiment does not limit this.

[0064] It should also be noted that the bottom surface of the triangular cross-section microprism body 311 is parallel to the surface of the substrate 32, and the bottom surface of the microprism body 311 is attached to or integrally connected to the substrate 32. The first and second side surfaces of the microprism body 311 can extend obliquely upward from both ends of the bottom surface and converge at the apex, forming a triangular cross-section prism structure. The triangular cross-section microprism body 311 has an incident light surface and an exit light surface, wherein the incident light surface is the bottom surface of the triangle, and the exit light surface is the first and second side surfaces of the triangle.

[0065] In the specific implementation, each color light-emitting chip 21 on the light board 2 emits a first light of its own color after being powered on. The first light propagates upward and passes through the substrate 32, then enters the interior of the microprism body 311, which has a triangular cross-section, from the bottom surface (light-incident surface). The light is refracted at the first and second sides (light-exit surfaces) of the microprism body 311. Since the cross-section of the microprism body 311 is triangular, its first and second sides have an inclined angle relative to the bottom surface. When the light is emitted, it is deflected to different degrees according to the angle of the apex of the triangle, thereby refracting and deflecting the originally divergent first light to a preset target angle to obtain the second light. Because this embodiment sets the cross-section of the microprism body 311 to be triangular, the microprism body 311 has a clear light-incident surface and a light-exit surface. The light is refracted at the light-exit surface, and the deflection direction of the light can be controlled by adjusting the angle of the apex of the triangle. The structure is simple and easy to mass-produce using an imprinting process.

[0066] For ease of understanding, the following explanation uses examples, but does not limit the specific implementation of this embodiment. Taking the RGB Mini LED backlight module as an example, the cross-section of the microprism body 311 is an isosceles triangle with a base width of 95μm and a height of 50μm. The bottom surface serves as the light-incident surface facing the lamp panel 2, while the first and second side surfaces serve as the light-emitting surfaces facing away from the lamp panel 2. The red light-emitting chip 21 emits a red first light with a center wavelength of 625nm. This light passes through the substrate 32 and enters the red microprism body 311 vertically from the bottom surface. When the light reaches the first side surface, it is refracted according to the refractive index of red light in the microprism material (n=1.553) and the apex angle (105°) of the microprism body 311, deflecting to a preset emission angle of 20° before exiting from the first side surface to obtain a red second light. The 525nm green light emitted by the green light-emitting chip 21 enters the green light microprism body 311 (vertices angle 95°, refractive index n=1.562) vertically from the bottom surface and exits from the first side at an exit angle of 20°. The 450nm blue light emitted by the blue light-emitting chip 21 enters the blue light microprism body 311 (vertices angle 85°, refractive index n=1.575) vertically from the bottom surface and exits from the first side at an exit angle of 20°. The three triangular cross-section microprism bodies 311 with different vertices ensure that the light rays with three different refractive indices achieve the same exit deflection angle, thereby guaranteeing the consistency of the spatial distribution of each color of light.

[0067] Furthermore, this embodiment can achieve the deflection of light of a corresponding color to the corresponding target angle by setting the angle of the apex angle of each microprism body 311, thereby enabling the deflection of light of a corresponding color to the corresponding target angle. Thus, the apex angle of the microprism body 311 corresponding to each color (i.e., Figure 2 middle The angle can be different, for example, referring to Figure 4 , Figure 4 This is a schematic diagram of the microprism bodies 311 corresponding to different apex angles in the second embodiment of the backlight module of this application. Figure 4 As shown, the microprism body 311 corresponding to the red light-emitting chip 21 can be referred to as the first microprism body, the microprism body 311 corresponding to the green light-emitting chip 21 can be referred to as the second microprism body, and the microprism body 311 corresponding to the blue light-emitting chip 21 can be referred to as the third microprism body. The height of the first microprism body, the second microprism body, and the third microprism body can all be 50μm, and the apex angle corresponding to the first microprism body can be 105° (i.e., Figure 4 In the case of α=105°, the apex angle corresponding to the body of the second microprism can be 95° (i.e., Figure 4 In the case of β=95°, the apex angle corresponding to the third microprism body can be 85° (i.e., Figure 4 (γ=85°).

[0068] To obtain the aforementioned apex angle, in this embodiment, the microprism body 311 has a light-incident surface facing the lamp panel 2 and two light-exit surfaces facing away from the lamp panel 2. The two light-exit surfaces are respectively the two legs of the triangle, and the included angle between the two light-exit surfaces forms the apex angle of the triangle. The triangle is an isosceles triangle, and the apex angle of the microprism body 311 corresponding to the color is... ;

[0069] in, The center wavelength of the first light ray corresponding to the color of the microprism body 311. The microprism body 311 is located at a center wavelength of The refractive index at that point, The target angle of the first ray of the corresponding color.

[0070] It is understandable that the two legs of the aforementioned triangle can be two equal lateral sides of an isosceles triangle. The vertex angle of the aforementioned triangle can be the included angle formed by the intersection of the two legs of an isosceles triangle (i.e.,...). Figure 2 middle ).

[0071] It is also understood that the aforementioned center wavelength can refer to the wavelength value corresponding to the point of maximum light intensity in the spectrum emitted by the light-emitting chip 21, for example, the center wavelength of the red light-emitting chip 21 is 625nm. The aforementioned target angle can be a preset deflection angle of the light emitted after refraction and deflection by the microprism body 311 relative to the normal direction.

[0072] In the specific implementation, each color light-emitting chip 21 emits a first light of its own color after being powered on, and the center wavelength of each first light of its color can be denoted as... The first ray propagates upwards and passes through the substrate 32, then enters the interior of the microprism body 311, which has an isosceles triangular cross-section, perpendicularly from the incident surface. When the ray reaches the two exiting surfaces (i.e., the two sides of the triangle), the refractive index of the material of the microprism body 311 decreases. Unlike the refractive index of air, light refracts at the two light-emitting surfaces.

[0073] Since the light-emitting chip 21 is positioned at the center of the corresponding microprism body 311 in this embodiment, it is a case of symmetrical incidence. For the case of symmetrical incidence, the angle of incidence of light on the microprism body 311 is... With apex The relationship can be:

[0074] According to Snell's law, the refraction of light on the inclined plane of a microprism satisfies the following:

[0075] in The angle of incidence of light on the microprism body 311. The angle of refraction (i.e. Figure 2 The angle between the second ray and the incident surface of the microprism body 311.

[0076] The deflection angle δ of the second ray relative to the normal direction can then be expressed as:

[0077] In order to achieve the same target deflection angle for light of different wavelengths Therefore, the following needs to be met:

[0078] However, in practical engineering calculations, to simplify the calculation process, the following approximate relationship can be used for rapid estimation:

[0079] in The vertex corresponding to the reference wavelength. This refers to the refractive index corresponding to the reference wavelength. In specific calculations, a color can be selected as a reference first (e.g., green light), and its apex angle can be set. Given a known value (e.g., a green light apex angle of 95°), the refractive index of the microprism material at the center wavelengths of red, green, and blue light is then measured. The apex of the reference wavelength. and refractive index Substitute the approximate formula to calculate the apex angles corresponding to red and blue light respectively.

[0080] Because this embodiment uses a formula and approximate formulas The vertex angle corresponding to each color is calculated so that light of different wavelengths obtains the same exit deflection angle after being refracted in their respective microprism bodies 311, thereby compensating for the difference in refractive index of light of different wavelengths caused by the material dispersion effect, and making the spatial distribution of light of each color tend to be consistent.

[0081] To facilitate understanding, the following examples are provided for illustration, but they do not constitute a specific limitation on this embodiment. Taking an RGB Mini LED backlight module as an example, the target angle is set. The angle is 20°. The center wavelength of green light, 525nm, is selected as the reference wavelength, and the corresponding apex angle of the microprism body 311 is... 95°, green light refractive index The refractive index of the microprism material at the red light center wavelength of 625 nm is 1.562. =95° =1.562、 Substituting 1.553 into the approximate relation Calculations were performed to obtain the vertex angle θ(625nm) ≈ 105° for the microprism body 311 corresponding to red light. The refractive index n(450nm) of the microprism material at the center wavelength of 450nm for blue light is 1.575. Substituting this into the same approximate formula, the vertex angle θ(450nm) ≈ 85° for the microprism body 311 corresponding to blue light was obtained. After manufacturing microprism bodies 311 with three different vertex angles based on the above calculations, the 625nm first ray emitted by the red light-emitting chip 21 is refracted by the red light microprism body 311 with a vertex angle of 105° and exits at a 20° angle; the 525nm first ray emitted by the green light-emitting chip 21 is refracted by the green light microprism body 311 with a vertex angle of 95° and also exits at a 20° angle; and the 450nm first ray emitted by the blue light-emitting chip 21 is refracted by the blue light microprism body 311 with a vertex angle of 85° and also exits at a 20° angle. Three different wavelengths of light, after being refracted by their respective corresponding microprism bodies 311, achieve the same exit deflection angle, thus becoming spatially consistent and effectively eliminating large-view-angle deflection caused by dispersion. When using UV-curable resins of different brands or formulations, it is only necessary to measure the refractive index values ​​of the resin at 625nm, 525nm, and 450nm to obtain the corresponding optimal apex angle parameters through the above calculation method. Therefore, this method is universal.

[0082] Furthermore, in order to enable the dielectric film 312 to transmit second light of the corresponding color and reflect second light of other colors, the following steps are continued... Figure 2 As shown, the dielectric film 312 includes several first material layers (i.e. Figure 2 The solid line portion in the dielectric film 312) and several layers of second material (i.e. Figure 2 (The dashed portion in the dielectric film 312), the refractive index of the first material layer is higher than that of the second material layer; The first material layer and the second material layer are alternately stacked.

[0083] It should be understood that the first material layer can be a single-layer thin film made of a high-refractive-index material, such as a film made of titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), or niobium pentoxide (Nb2O5). The second material layer can be a single-layer thin film made of a low-refractive-index material, such as a film made of silicon dioxide (SiO2) or magnesium fluoride (MgF2). The alternating stacking arrangement can refer to the first material layer and the second material layer being periodically stacked in the order of one layer of the first material layer, one layer of the second material layer, one layer of the first material layer, and one layer of the second material layer.

[0084] It should also be understood that the dielectric film 312 and the microprism body 311 are directly connected through a coating process or indirectly connected through an adhesive layer. This embodiment uses direct contact connection through a coating process for explanation, but does not impose specific limitations on this embodiment. The total number of the aforementioned first material layers and second material layers can be set to an odd number or an even number of layers according to design needs. This embodiment uses an odd number of layers (e.g., 19 layers) for explanation, but does not impose specific limitations on this embodiment.

[0085] In its implementation, the second light ray exits from the microprism body 311 and reaches the dielectric film 312 disposed on the microprism body 311. The dielectric film 312 is composed of alternating layers of a first material layer and a second material layer, wherein the refractive index of the first material layer is higher than that of the second material layer. Due to the difference in refractive indices between the two material layers, light undergoes partial transmission and partial reflection when passing through each layer interface. By designing the thickness of each layer and the total number of layers, the reflected light from each layer interface can undergo constructive or destructive interference at specific wavelengths, thereby achieving selective transmission or reflection of light of different wavelengths.

[0086] Specifically, when the wavelength of the second light beam matches the designed wavelength of the dielectric film 312, the reflected light from the interface of each layer has a high total transmittance due to destructive interference, meaning the second light beam is allowed to pass through. When stray light of other colors reaches the dielectric film 312, its reflected light is reflected back downwards due to constructive interference. After being reflected back downwards, the stray light is reflected by the backplate 1 and re-enters the optical path, where it can be reused. Because this embodiment uses alternating layers of a high-refractive-index first material layer and a low-refractive-index second material layer to construct the dielectric film 312, selective transmission and reflection of light of different wavelengths are achieved using the principle of optical interference. This allows light of corresponding colors to pass through efficiently while stray light of non-corresponding colors is reflected and recovered, thereby improving light energy utilization and color purity.

[0087] For ease of understanding, combined with Figure 5 To explain, Figure 5 The reflectance / transmittance curves of the 312 dielectric film are optimized for red light. (See diagram.) Figure 5 As shown, the horizontal axis represents wavelength (nm), and the vertical axis represents reflectivity / refractive index (%). This dielectric film 312 exhibits a high transmittance T (approximately 85% or higher) at the red light center wavelength of 625nm. Figure 5 The transmittance curve T near 625nm is at its peak, indicating that the red second ray can efficiently pass through the dielectric film 312. Simultaneously, the dielectric film 312 exhibits high reflectance R at the blue light center wavelength of 450nm and the green light center wavelength of 525nm, corresponding to… Figure 5 The reflectance curves R near 450nm and 525nm are at their peaks (reflectance is approximately 95% or higher), indicating that stray blue and green light are efficiently reflected back when they reach the dielectric film 312. Meanwhile, the transmittance curves T are at their troughs at these two wavelengths, indicating that stray blue and green light are difficult to transmit.

[0088] In practical design, taking the red light optimized dielectric film 312 as an example, this dielectric film 312 is disposed on the light-emitting surface of the first microprism unit 31 corresponding to red light. It is composed of alternating layers of TiO2 with a refractive index of approximately 2.35 (at 550 nm) as the first material layer and SiO2 with a refractive index of approximately 1.46 (at 550 nm) as the second material layer, with a total of 19 layers and a total thickness of approximately 2.08 μm. The thickness of each layer can be optimized by optical software so that the transmittance of the dielectric film 312 at the red light center wavelength of 625 nm reaches more than 85%, while the reflectance at the green light center wavelength of 525 nm and the blue light center wavelength of 450 nm reaches more than 95%. The second red ray (625nm) is emitted from the microprism body 311 and reaches the red light optimized dielectric film 312. Since the design wavelength of the dielectric film 312 matches the red light, the reflected light at each interface of the second red ray undergoes destructive interference when passing through the 19 layers of TiO2 / SiO2 alternating layers, allowing the second red ray to pass through efficiently (transmittance ≥85%). When stray green light (525nm) and stray blue light (450nm) from the adjacent green or blue light-emitting chip 21 reach the dielectric film 312, due to the wavelength mismatch with the design wavelength, the reflected light at each interface undergoes constructive interference, and the stray green and stray blue light are reflected back downwards (reflectance ≥95%). After being reflected by the backplate 1, they can re-enter the optical path and be reused. Similarly, the green light-optimized dielectric film 312 (with a total thickness of approximately 1.76 μm) allows green light to pass through efficiently while reflecting red and blue light back, and the blue light-optimized dielectric film 312 (with a total thickness of approximately 1.50 μm) allows blue light to pass through efficiently while reflecting red and green light back. Through the dielectric films 312 arranged in the above-mentioned partitions, light of each color is efficiently transmitted in its corresponding microprism unit 31, while stray light is reflected and recovered, thereby improving the overall light energy utilization and color purity of the backlight module.

[0089] Reference Figure 6 as well as Figure 7 , Figure 6 This is a comparison chart of color shift values ​​between the differentiated vertex angle scheme and the unified vertex angle scheme. Figure 7 This is a comparison chart of optical distances between the differentiated apex angle scheme and the unified apex angle scheme.

[0090] It is understandable that the aforementioned color cast value can be a quantitative indicator used to measure the degree of color deviation when a displayed image is viewed from different angles, i.e., using... Figure 6 In the figure, Δu'v' represents a smaller value, indicating a smaller color change with varying viewing angles, i.e., a less pronounced color cast. The aforementioned optical distance can be the vertical distance between the light-emitting surface of the lamp panel 2 and the light-incident surface of the microprism film 3, i.e., using... Figure 7 The OD value indicates that the smaller the value, the thinner the backlight module.

[0091] exist Figure 6 In this context, Scheme A can refer to a comparative scheme using a traditional BEF prism film, where the microprism apex angle is uniform and there is no dielectric film 312. Scheme B can refer to a comparative scheme using a uniform apex angle microprism and having a dielectric film 312. Scheme C can refer to a comparative scheme using a differentiated apex angle microprism but without a dielectric film 312. Scheme D can refer to the scheme of this invention, i.e., the technical scheme that simultaneously uses differentiated apex angle microprisms and a dielectric film 312. The above comparative data can be obtained through optical simulation software or through actual sample testing. This embodiment uses simulation data for comparison and explanation.

[0092] In practical implementation, to verify the technical effect of the present invention, the optical performance of the present invention was compared with that of three comparative schemes. Under wide viewing angle conditions (e.g., 60° viewing angle), the color shift value Δu'v' of the four schemes was measured respectively, and the measurement results are as follows. Figure 6 As shown, the horizontal axis can represent four schemes, and the vertical axis can represent the color deviation value Δu'v'.

[0093] Simultaneously, the optical distance (OD) values ​​for the four schemes were measured, and the measurement results are as follows: Figure 7 As shown, the horizontal axis represents four different schemes, and the vertical axis represents the OD value, with the unit being mm. Considering that color cast and OD value are two important indicators for evaluating the optical performance of backlight modules in practical engineering, a smaller color cast indicates a less pronounced color cast at a wide viewing angle, and a smaller OD value indicates a thinner backlight module, both indicators are evaluated simultaneously in the above comparative test.

[0094] The comparison results show that the color shift value Δu'v' of scheme D is 0.005, which is significantly lower than that of scheme A (0.015), scheme B (0.009), and scheme C (0.011), indicating that the scheme of this embodiment is superior to the comparative schemes in terms of color shift control at a large viewing angle. Meanwhile, the OD value of scheme D is 2.8mm, which is significantly lower than that of scheme A (5.0mm), scheme B (3.5mm), and scheme C (4.2mm), indicating that the scheme of this embodiment is superior to the comparative schemes in terms of backlight module thinning. Because this application utilizes the synergistic effect of the differentiated apex-angle microprism and the dielectric film 312, compared to schemes B and C which only use a single method, this application can simultaneously and significantly reduce both the color shift value and the OD value, and the improvement is greater than the sum of the improvement when using either method alone, thereby achieving both improved display quality and backlight module thinning.

[0095] Reference Figure 8 , Figure 8 This is a schematic diagram of the gradient layer 313 in the third embodiment of the backlight module of this application, as shown below. Figure 8 As shown, a third embodiment of this application is presented.

[0096] To reduce Fresnel reflection loss and improve the overall light energy utilization of the backlight module. For example... Figure 8 As shown, in this embodiment, each of the microprism units 31 further includes a gradient layer 313; The gradient layer 313 is disposed on the side of the dielectric film 312 opposite to the microprism body 311; The gradient layer 313 is used to output the third light after the second light of the corresponding color is refracted at least twice between the dielectric film 312 and the air through different equivalent refractive indices. In this process, at least twice the equivalent refractive index gradually changes from the refractive index of the dielectric film 312 to the refractive index of the air.

[0097] It should be noted that the aforementioned gradient layer 313 can be an optical functional layer disposed on the surface of the dielectric film 312 away from the microlens body, used to achieve a smooth transition of refractive index, such as a subwavelength nanograting structure. The aforementioned equivalent refractive index refers to the equivalent optical refractive index value macroscopically exhibited by the gradient layer 313 when light passes through it, and can be between the refractive index of the material constituting the dielectric film 312 and the refractive index of air. In this embodiment, the equivalent refractive index at the interface between the gradient layer 313 and air gradually changes to be close to the refractive index of air, thereby reducing Fresnel reflection loss at the interface.

[0098] It should also be noted that the gradient layer 313 and the dielectric film 312 can be directly connected via nanoimprint lithography or indirectly connected via coating. This embodiment uses direct contact connection via nanoimprint lithography for explanation, but does not impose specific limitations on this embodiment. The gradient layer 313 can be disposed on the entire surface of the dielectric film 312 or only on a local area of ​​the dielectric film 312. This embodiment uses disposal on the entire surface of the dielectric film 312 for explanation. In this embodiment, the gradient layer 313 can be composed of a subwavelength grating structure with a grating period smaller than the incident light wavelength, and the equivalent refractive index gradually changes along the light emission direction.

[0099] In a specific implementation, the second light ray passing through the dielectric film 312 then enters a gradient layer 313 disposed on the side of the dielectric film 312 facing away from the microprism body 311. The gradient layer 313 has multiple sub-regions with different equivalent refractive indices arranged sequentially in the direction of the second light ray's emission. The equivalent refractive index of the sub-regions gradually changes from the refractive index of the dielectric film 312 to the refractive index of air. When the second light ray passes through the gradient layer 313, it undergoes at least two refractions with different equivalent refractive indices in sequence. A refraction occurs once after passing through each sub-region, and the direction of the light ray is finely adjusted step by step, ultimately outputting the third light ray.

[0100] Because the equivalent refractive index of the gradient layer 313 changes gradually rather than abruptly, the refraction experienced by the light is also a successive fine adjustment rather than a one-time large deflection, thereby reducing Fresnel reflection loss caused by the abrupt change in refractive index when the light travels from the dielectric film 312 to the air. The gradient layer 313 performs a gradual refractive index transition on the second light ray before outputting the third light ray, which then enters the air after exiting the gradient layer 313. In this embodiment, because the gradient layer 313 causes the second light ray to undergo at least two refractions with different equivalent refractive indices sequentially during its journey from the dielectric film 312 to the air, the abrupt change in refractive index is transformed into a gradual transition, thereby reducing Fresnel reflection loss and improving the overall light energy utilization of the backlight module.

[0101] For ease of understanding, the following explanation uses examples, but does not limit the specific implementation of this embodiment. Taking a subwavelength nanograting gradient layer 313 disposed outside the red light optimization dielectric film 312 as an example, this gradient layer 313 is located on the side of the red light optimization dielectric film 312 facing away from the red light microprism body 311. The refractive index of the red light optimization dielectric film 312 is approximately 1.46 to 2.35, while the refractive index of air is 1.0. The gradient layer 313 is composed of a subwavelength nanograting with a period of 580 nm, a depth of 120 nm, and a duty cycle of 0.50. This grating structure is macroscopically equivalent to a transition layer with a gradually changing refractive index. After the second red ray (625 nm) is emitted from the red light microprism body 311, it first passes through the red light optimization dielectric film 312 (transmittance ≥ 85%), and then enters the gradient layer 313.

[0102] In the gradient layer 313, the second red ray passes through multiple sub-regions where the equivalent refractive index gradually changes from 1.46 to 1.0. After multiple refractions, it finally exits from the gradient layer 313 and enters the air, becoming the third red ray. Because the gradient layer 313 transforms the abrupt change in refractive index into a gradual transition, the interface reflection loss of the second red ray when it travels from the dielectric film 312 to the air is significantly reduced. By setting corresponding gradient layers 313 in each color microprism unit 31, the transmittance of different colors of light when traveling from the dielectric film 312 to the air is significantly improved, and the large-view-angle color deviation performance is further improved while increasing light energy utilization.

[0103] Furthermore, in order to achieve a gradual change in refractive index, continue as follows Figure 8 In this embodiment, the gradient layer 313 is a grating structure, and the period of the grating structure corresponding to the color is... ;

[0104] in, The period of the grating structure corresponding to the color. This is the subwavelength margin factor. The center wavelength of the second ray corresponding to the color, Let be the refractive index of the air.

[0105] It is understood that the aforementioned grating structure can be a micro / nano optical structure with a periodic concave-convex profile on its surface, such as a subwavelength nanograting. The period of the aforementioned grating structure can be the center distance between two adjacent protrusions or two adjacent grooves on the grating structure. The aforementioned subwavelength margin coefficient can be a scaling factor used to ensure that the grating period is less than the center wavelength of the corresponding color; in this embodiment, the value can be between 0.85 and 0.95.

[0106] In the specific implementation, each color-emitting chip 21 emits a first light of its own color after being powered on. The center wavelength of each first light is λc, and the subscript c represents the color channel. The first light propagates upward and passes through the substrate 32 before entering the microprism body 311. The microprism body 311 refracts and deflects the first light to a preset target angle to obtain a second light. The second light exits from the microprism body 311 and reaches the dielectric film 312 disposed on the microprism body 311. The dielectric film 312 allows the second light of the corresponding color to pass through based on its spectral selectivity. The second light that passes through the dielectric film 312 then enters the grating structure disposed on the side of the dielectric film 312 opposite to the microprism body 311.

[0107] The period Λc(0) of the grating structure can be expressed by the formula The calculations determine that qc is the subwavelength margin coefficient, which can be between 0.85 and 0.95, λc is the center wavelength of the second ray of the corresponding color, and n0 is the refractive index of air (which can be 1.0). Since qc is less than 1, the period Λc(0) of the grating structure is less than the center wavelength λc of the corresponding color, therefore the grating structure belongs to the subwavelength grating.

[0108] When the second ray passes through the subwavelength grating structure, because the grating period is smaller than the wavelength, the ray will not produce higher-order diffraction. Macroscopically, the grating structure only appears as a transition layer with a gradually changing equivalent refractive index. As the second ray passes through this transition layer, the equivalent refractive index can gradually change from the refractive index of the dielectric film 312 to the refractive index of air, thereby reducing interface reflection losses.

[0109] Since this embodiment calculates the period of the grating structure using the formula Λc(0)=qc·λc / n0, the grating period is smaller than the center wavelength of the corresponding color, ensuring that the grating structure works in subwavelength mode. Thus, macroscopically, it is manifested as an equivalent refractive index gradient layer 313, effectively reducing Fresnel reflection loss when light travels from the dielectric film 312 to the air.

[0110] To facilitate understanding, the following examples illustrate this. Taking the grating structure in an RGB Mini LED backlight module as an example, the refractive index n0 of air is taken as 1.0. The center wavelength λc of the second ray corresponding to red light is 625nm, and the subwavelength margin coefficient qc is taken as 0.928. Substituting into the formula Λc(0) = 0.928 × 625nm / 1.0, the grating structure period Λc(0) corresponding to red light is calculated to be 580nm. The center wavelength λc of the second ray corresponding to green light is 525nm, and qc is taken as 0.914. Substituting into the formula, the grating structure period corresponding to green light is calculated to be 480nm. The center wavelength λc of the second ray corresponding to blue light is 450nm, and qc is taken as 0.889. Substituting into the formula, the grating structure period corresponding to blue light is calculated to be 400nm. The periods of the grating structures of the three colors are all smaller than their respective center wavelengths (580nm<625nm, 480nm<525nm, 400nm<450nm), therefore they all belong to subwavelength gratings.

[0111] When the red second ray passes through a red grating structure with a period of 580 nm, no higher-order diffraction occurs; instead, the equivalent refractive index gradually changes from the refractive index of dielectric film 312 to the refractive index of air (1.0), thus reducing interface reflection loss. Similarly, the green and blue second rays, passing through corresponding grating structures with periods of 480 nm and 400 nm respectively, also achieve the same gradual refractive index transition effect. By setting subwavelength grating structures for different colors, the transmittance of each color light when incident from dielectric film 312 to air is improved, and the difference in transmittance of the three colors at large angles is further reduced.

[0112] Furthermore, in order to obtain the depth and duty cycle of the grating structure, in this embodiment, the depth of the grating structure is hc and the duty cycle is fc; In the grating structure, the period is When the depth is hc and the duty cycle is fc, the corresponding objective function value is minimized. The objective function is:

[0113] in, The value of the objective function. The incident angle of the first light ray to the corresponding microprism body 311. The incident angle The corresponding preset viewpoint weight coefficients, The transmittance of the red third ray output by the grating structure. The transmittance of the third green ray output by the grating structure. The transmittance of the blue third ray output by the grating structure. The preset average transmittance weighting coefficient, The average transmittance of the c-th color within the preset evaluation angle range.

[0114] It should be understood that the depth of the aforementioned grating structure can be the vertical distance between the top of the protrusion and the bottom of the groove on the surface of the grating structure. The aforementioned duty cycle can be the ratio of the width of the protrusion portion to the total width of the period within one cycle of the grating structure. The aforementioned objective function can be a mathematical expression used to evaluate the performance of the grating structure; the smaller the function value, the better the overall performance of the grating structure. In this embodiment, the depth and duty cycle of the grating structure can be obtained by minimizing the aforementioned objective function.

[0115] It should also be understood that the aforementioned incident angle can be the angle between the first ray and the normal direction when it is incident on the microprism body 311. The aforementioned preset viewing angle weighting coefficient can be a weighted value preset according to the importance of different viewing angles to display quality. In this embodiment, the weighting coefficient of the positive viewing angle can be set to be greater than the weighting coefficient of the large viewing angle.

[0116] It should be noted that the aforementioned average transmittance can be the arithmetic mean of the transmittance of a certain color light at various incident angles within a preset evaluation angle range. The aforementioned preset evaluation angle range can be a pre-defined interval of incident angles used to evaluate the performance of the grating structure, such as 0° to 60° or 0° to 75°. This embodiment uses 0° to 60° as the preset evaluation angle range for explanation, but does not impose specific limitations on this embodiment. The aforementioned preset average transmittance weighting coefficient can be a preset coefficient used to balance the priority between the transmittance dispersion of each color and the average transmittance; it can be set according to actual conditions.

[0117] In the specific implementation, after determining the grating structure period Λc(0) corresponding to each color, the depth hc and duty cycle fc of the grating structure can be jointly scanned and optimized using the grating structure period Λc(0) as the center.

[0118] Specifically, multiple different combinations of depth values ​​(denoted as hc) and duty cycle values ​​(denoted as fc) can be set. For each parameter combination (Λc(0), hc, fc), at each incident angle θ within a preset evaluation angle range (e.g., 0° to 60°), the transmittance TR(θ), transmittance TG(θ), and transmittance TB(θ) of the red third ray output by the grating structure are measured respectively. Then, the dispersion (i.e., variance) Var{TR(θ), TG(θ), TB(θ)} of the three colors at each incident angle θ is calculated, where Var represents the variance. This dispersion is multiplied by the corresponding preset viewing angle weight coefficient wθ and then summed over all incident angles θ to obtain the first part of the objective function, i.e., the result of the calculation. .

[0119] Simultaneously, the average transmittance of red, green, and blue within the preset evaluation angle range can be calculated separately. R, G and B, then calculate [1] for each color. c]² is multiplied by a preset average transmittance weighting coefficient α, and then summed for all colors to obtain the second part of the objective function, i.e., the result is obtained. .

[0120] Then, add the first part and the second part together to obtain the objective function value J corresponding to this set of parameters. Repeat the above calculation process for all parameter combinations to obtain a series of objective function values ​​J. Select the depth hc and duty cycle fc corresponding to the set of parameters with the smallest function value as the final grating structure parameters.

[0121] Since this embodiment uses the objective function J=Σθ wθ·Var{TR(θ),TG(θ),TB(θ)}+α·Σc[1 c]² The depth and duty cycle of the grating structure are optimized so that the optimized grating structure has the smallest dispersion of the three-color light transmittance and the highest average transmittance of each color at each incident angle, thereby achieving consistency and high transmittance of the three-color light transmittance over a wide viewing angle.

[0122] For ease of understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. Taking the optimization of the grating structure corresponding to red as an example, after the period Λc(0) is determined to be 580nm, the preset evaluation angle range can be set to 0° to 60°. Within this range, five sampling angles of 0°, 15°, 30°, 45° and 60° are selected as the evaluation incident angles θ, and the corresponding preset viewing angle weight coefficients wθ are set to 1.0, 0.9, 0.8, 0.7 and 0.6, respectively. Then, a joint scan is performed on the depth hc in the range of 80nm to 150nm and the duty cycle fc in the range of 0.45 to 0.50. For each set of parameters, the transmittance of the red, green and blue third rays is measured at the five sampling angles to obtain TR(θ), TG(θ) and TB(θ). The dispersion Var{TR(θ), TG(θ), TB(θ)} of the three-color transmittance at each angle is calculated, multiplied by the corresponding wθ and summed to obtain the first part of the objective function.

[0123] Simultaneously, the average transmittance of red, green, and blue in the range of 0° to 60° was calculated separately. R, G and B, setting α to 0.5, calculate the [1] of each color. The summation of c² and multiplied by 0.5 yields the second part of the objective function.

[0124] The two parts are added together to obtain the objective function value J of this set of parameters. This calculation is repeated for all parameter combinations to find the parameter combination that minimizes J. Through scanning optimization, for example, under a period of 580nm, the objective function value J is minimized when the depth hc is 120nm and the duty cycle fc is 0.50. Therefore, the depth of the red grating structure is determined to be 120nm and the duty cycle to be 0.50. Similarly, scanning optimization is performed on the green grating structure under a period of 480nm, determining a depth of 100nm and a duty cycle of 0.48. Scanning optimization is performed on the blue grating structure under a period of 400nm, determining a depth of 85nm and a duty cycle of 0.45.

[0125] Furthermore, the grating structure parameters obtained through the above optimization process ensure that, within a preset evaluation angle range of 0° to 60°, the transmittance dispersion of the three colors is minimized and the average transmittance of each color is maximized. Figure 9 , Figure 9 The simulated transmittance curves of the grating structure at different incident angles are shown below. Figure 9 As shown, Figure 9 R- without grating can be the transmittance curve of the red light channel without gradient layer 313. G- without grating can be the transmittance curve of the green light channel without gradient layer 313. B- without grating can be the transmittance curve of the blue light channel without gradient layer 313. R- with grating can be the transmittance curve of the red light channel with gradient layer 313. G- with grating can be the transmittance curve of the green light channel with gradient layer 313. B- with grating can be the transmittance curve of the blue light channel with gradient layer 313. The three-color difference can be the maximum difference between the transmittance of red, green and blue at the same incident angle.

[0126] To verify the effect of the gradient layer 313 (i.e., the grating structure) on improving transmittance, this embodiment uses Finite Difference Time Domain (FDTD) optical simulation software to conduct simulation tests on schemes without and with the gradient layer 313. During the simulation, the incident angle is set to gradually change from 0° to 75°, and the transmittance of red, green, and blue colors at different incident angles is measured. For the scheme without the gradient layer 313, the transmittance of light is directly measured when it travels from the dielectric film 312 to the air. For the scheme with the gradient layer 313, the transmittance of light is measured when it passes through the dielectric film 312 and the gradient layer 313 sequentially before traveling to the air.

[0127] The measurement results from the two schemes were plotted as curves showing the transmission rate as a function of the incident angle. Figure 9 As shown. Figure 9In the diagram, the horizontal axis represents the incident angle, measured in degrees (°), ranging from 0° to 75°. The vertical axis represents the transmittance, measured in percentages (%), ranging from 0% to 100%. The aforementioned incident angle can be the angle between the first ray and the normal direction when it is incident on the microprism body 311. The aforementioned transmittance can be the ratio of the optical power of the emitted ray after passing through the grating structure to the optical power of the incident ray.

[0128] Figure 9 The six curves can respectively represent the transmittance trends of red light without a grating, red light with a grating, green light without a grating, green light with a grating, blue light without a grating, and blue light with a grating as a function of the incident angle. From Figure 9 As can be seen, at a 0° incident angle (i.e., normal viewing angle), in the scheme without the gradient layer 313, the red transmittance is approximately 92%, the green transmittance is approximately 91%, and the blue transmittance is approximately 90%, with a difference of approximately 2% in the three colors' transmittance. In the scheme with the gradient layer 313, the red transmittance is approximately 94%, the green transmittance is approximately 93%, and the blue transmittance is approximately 93%, with a difference of approximately 1% in the three colors' transmittance.

[0129] At an incident angle of 30°, in the scheme without the gradient layer 313, the red transmittance is approximately 85%, the green transmittance is approximately 82%, and the blue transmittance is approximately 78%, with a difference of approximately 7% in the three colors. In the scheme with the gradient layer 313, the red transmittance is approximately 89%, the green transmittance is approximately 88%, and the blue transmittance is approximately 87%, with a difference of approximately 2% in the three colors.

[0130] At a 45° incident angle, in the scheme without the gradient layer 313, the red transmittance is approximately 75%, the green transmittance is approximately 70%, and the blue transmittance is approximately 63%, with a difference of approximately 12% in the three colors. In the scheme with the gradient layer 313, the red transmittance is approximately 82%, the green transmittance is approximately 80%, and the blue transmittance is approximately 78%, with a difference of approximately 4% in the three colors.

[0131] At an incident angle of 60°, in the scheme without the gradient layer 313, the red transmittance is approximately 60%, the green transmittance is approximately 52%, and the blue transmittance is approximately 42%, with a difference of approximately 18% in the three colors. In the scheme with the gradient layer 313, the red transmittance is approximately 72%, the green transmittance is approximately 69%, and the blue transmittance is approximately 66%, with a difference of approximately 6% in the three colors.

[0132] At an incident angle of 75°, in the scheme without the gradient layer 313, the red transmittance is approximately 40%, the green transmittance is approximately 30%, and the blue transmittance is approximately 20%, with a difference of approximately 20% in the three colors' transmittance. In the scheme with the gradient layer 313, the red transmittance is approximately 55%, the green transmittance is approximately 50%, and the blue transmittance is approximately 46%, with a difference of approximately 9% in the three colors' transmittance.

[0133] The above data shows that after setting the gradient layer 313, the transmittance of each color at different incident angles is significantly improved, and the transmittance difference between the three colors is significantly reduced. In particular, at a 60° incident angle, the transmittance difference of the three colors is reduced from 18% before setting the gradient layer 313 to 6% after setting the gradient layer 313. The emission intensity of the three colors is basically the same, and the white balance is well maintained.

[0134] Reference Figure 10 , Figure 10 This is a curve graph for comparing color uniformity tests. (Example) Figure 10 As shown, Figure 10 Option A can be a comparative option using a traditional BEF prism film, where the microprism apex angle is uniform and it lacks a spectrally selective film layer and a gradient layer 313. Option D can be a technical solution in this invention without the gradient layer 313, that is, it only includes the microprism body 311 and the dielectric film 312 but does not include the gradient layer 313. Option D+ can refer to the complete technical solution in this invention with the gradient layer 313, that is, it simultaneously includes the microprism body 311, the dielectric film 312, and the gradient layer 313.

[0135] In practical implementation, to verify the technical effect of the gradient layer 313, a large-view-angle color deviation comparison test was conducted between the present invention and the comparative scheme. Scheme A uses a traditional BEF prism film, whose microprism apex angle is a uniform angle and does not have a spectrally selective film layer and gradient layer 313. Scheme D uses the differentiated apex angle microprism and spectrally selective dielectric film 312 layer of the present invention, but does not set the gradient layer 313 on the outside of the dielectric film 312. Scheme D+ adopts the complete technical solution of the present invention, that is, it simultaneously includes a differentiated apex angle microprism, a spectrally selective dielectric film 312 layer, and a gradient layer 313 (i.e., a subwavelength nanograting structure).

[0136] Under wide viewing angle conditions (0° to 80°), the color difference value Δu'v' of the three schemes was measured as a function of viewing angle, as shown below. Figure 10 As shown. Figure 10 In the figure, the horizontal axis represents the viewing angle, measured in degrees (°), ranging from 0° to 80°. This viewing angle can refer to the angle between the observer's line of sight and the normal direction of the display panel. The vertical axis represents the color difference value Δu'v', which can be calculated using optical simulation software or obtained through optical testing of actual samples. This embodiment uses simulation data for comparison and illustration. The figure also indicates the human eye's perceptible threshold Δu'v' = 0.005 (i.e.,...). Figure 10 The color difference is defined as a perceptible threshold; when the color difference value is below this threshold, the human eye cannot perceive the color shift. The three curves in the figure represent the color difference values ​​of schemes A, D, and D+ as a function of viewing angle.

[0137] from Figure 10As can be seen, the color difference value of Scheme A (traditional BEF prism film) increases rapidly with the increase of viewing angle, exceeding the perceptible threshold of 0.005 at approximately 20° viewing angle, and is approximately 0.015 at 60° viewing angle, indicating a significant color shift when viewed from a large angle. The color difference value of Scheme D (this invention without nanograting) increases at a slower rate than Scheme A, exceeding the perceptible threshold of 0.005 at approximately 60° viewing angle, and is approximately 0.008 at 70° viewing angle, indicating a slight improvement in color shift compared to Scheme A, but still perceptible to the human eye. Scheme D+ (this invention with nanograting) exhibits the slowest rate of increase in color difference value, consistently remaining below the perceptible threshold of 0.005 throughout the entire viewing angle range from 0° to 67°, with a color difference value of approximately 0.003 at 60° viewing angle, indicating no significant change in image color when viewed from a large angle, and the color shift has been suppressed to a level imperceptible to the human eye.

[0138] The above data shows that by further adding a gradient layer 313 on the basis of the differentiated apex microprism and the spectrally selective dielectric film 312 layer, the large-view chromatic aberration is further significantly improved.

[0139] Furthermore, continue as Figure 1 As shown, in this embodiment, the backlight module further includes: a diffuser plate 5; The diffuser plate 5 is disposed at the end of the microprism film 3 away from the lamp plate 2, and is used to uniformly emit the third light rays emitted by the microprism film 3.

[0140] It should be understood that the aforementioned diffuser plate 5 can be an optical material used to further homogenize light, such as a plate-like structure with light scattering function made of polymethyl methacrylate (PMMA) or polycarbonate (PC).

[0141] It should also be understood that in this embodiment, the diffuser plate 5 can be disposed on the side of the microprism film 3 away from the lamp plate 2, and the side of the diffuser plate 5 away from the microprism film 3 can be provided with a liquid crystal display panel 6.

[0142] In its implementation, the gradient layer 313 refracts the second light rays through at least two refractions at different equivalent refractive indices between the dielectric film 312 and the air, outputting the third light rays. Each color of the third light ray exits from its respective microprism unit 31, propagates upwards, and reaches the diffuser plate 5. The diffuser plate 5 scatters and diffuses the incident third light rays, further homogenizing the spatial distribution of the light, resulting in emitted light rays after a second homogenization process. The light rays homogenized by the diffuser plate 5 then exit uniformly from the exit surface of the diffuser plate 5, collectively forming a uniform backlight source.

[0143] Because this embodiment uses the diffuser plate 5 to homogenize the third light rays of various colors emitted from the microprism film 3, the distribution of light in space is more uniform, eliminating the brightness fluctuations that may be caused by the periodic structure of the microprism array, and further improving the surface uniformity of the backlight source.

[0144] Furthermore, to achieve the above objectives, this embodiment also proposes a display, which includes a display panel (i.e., Figure 1 The display panel 6), a timing controller, and a backlight module as described above are provided on the back of the display panel, and the timing controller is electrically connected to the backlight module. The timing controller is used to output display signals to the backlight module; The backlight module is used to provide a backlight source to the display panel according to the display signal.

[0145] Since this display adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0146] Furthermore, considering that the backlight module is equipped with optical film layers such as dielectric film 312, which will affect the brightness, in order to ensure that the actual emitted brightness of each color light can still be consistent with the design target, in this embodiment, the timing controller is also used to acquire the color information of the display screen, and determine the target brightness ratio corresponding to each pixel according to the preset white balance target and the color information. The pixel includes at least two different colors of light-emitting chips 21.

[0147] It should be noted that the timing controller mentioned above can be a control chip or control circuit used to control the light emission timing and brightness of each light-emitting chip 21 in the backlight module, such as a field-programmable gate array (FPGA) or a microcontroller unit (MCU), etc. This embodiment does not limit it.

[0148] It should also be noted that the aforementioned color information can be the color data of each pixel in the displayed image, such as the grayscale values ​​or brightness values ​​of red, green, and blue. The aforementioned white balance target can be a preset ratio of the brightness of each color used to ensure that a white image presents standard white under different brightness levels.

[0149] In this embodiment, the timing controller is also used to acquire the characteristic curves of each of the light-emitting chips 21, and to back-calculate the initial driving current that satisfies the target brightness ratio based on each of the characteristic curves. The timing controller is also used to obtain the actual transmittance of the backlight module for each color, and to obtain the corresponding target driving current according to the preset conversion factor, the actual transmittance of each color and the corresponding initial driving current. The timing controller is also used to output a corresponding display signal to the backlight module according to the corresponding target drive current.

[0150] Understandably, the aforementioned characteristic curve can be the curve showing the relationship between the driving current of the light-emitting chip 21 and the luminous intensity. The aforementioned actual transmittance can be the actual transmission ratio of each optical film layer in the backlight module to the corresponding color light, such as the actual transmittance of the red light optimization dielectric film 312 to the red light band.

[0151] It is also understood that the aforementioned preset conversion factor can be a coefficient used to convert the initial drive current into the target drive current. The aforementioned display signal can be an electrical signal used to drive the light-emitting chip 21 to emit light, such as a pulse width modulation (PWM) signal or an analog voltage signal, etc., and this embodiment does not limit it.

[0152] In its implementation, the timing controller first acquires the color information of the image to be displayed. This color information may include color data for each pixel, such as red, green, and blue brightness values. Then, it processes the acquired color information according to a preset white balance target to determine the target brightness ratios that the red, green, and blue light-emitting chips 21 corresponding to each pixel need to achieve. The preset white balance target can be set according to actual conditions; for example, it can be that the brightness ratios of red, green, and blue at any brightness level ensure that the mixed white meets standard white balance requirements.

[0153] The timing controller then acquires the brightness-drive current characteristic curve (i.e., electro-optic conversion characteristic curve) of each light-emitting chip 21, and performs reverse calculation based on the characteristic curve of each light-emitting chip 21, that is, it calculates the initial drive current required to meet the target brightness ratio from the target brightness ratio. The initial drive current corresponding to the red light-emitting chip 21 is denoted as... The initial driving current corresponding to the green light-emitting chip 21 is denoted as The initial driving current corresponding to the blue light-emitting chip 21 is denoted as... .

[0154] Considering that the various optical layers in the backlight module (such as dielectric film 312, gradient layer 313, diffuser 5, etc.) will cause different degrees of transmission loss to different colors of light, the timing controller can also obtain the actual transmittance parameters of the backlight module for each color, where the actual transmittance of red can be denoted as... The actual transmittance of green can be denoted as: The actual transmittance of blue can be denoted as: Meanwhile, the timing controller can also obtain the electro-optical conversion efficiency normalization factor η of each light-emitting chip 21, which can be used to correct the nonlinear relationship between the driving current and the luminous brightness, and can be determined based on the measured brightness-current characteristic curve of the light-emitting chip 21.

[0155] Subsequently, the timing controller can calculate based on the preset conversion factor (i.e., the electro-optical conversion efficiency normalization factor η), the actual transmittance of each color, and the corresponding initial drive current. Specifically, the initial drive current can be divided by the product of the actual transmittance of the corresponding color and the electro-optical conversion efficiency normalization factor to obtain the target drive current for each color, i.e., the target drive current. The following relationship must be satisfied:

[0156] Taking the red channel as an example, the timing controller can calculate the red target drive current. = This is to compensate for the difference in electro-optical conversion efficiency of the light-emitting chip 21 and the transmission loss caused by the optical film. Similarly, the green target driving current... = Blue target driving current = After compensation and correction, the actual output brightness of each color channel is... It can be satisfied:

[0157] That is, the actual emitted brightness of each color channel after compensation remains consistent with the initial design brightness, where K is a proportionality coefficient. Next, a corresponding display signal (e.g., a PWM dimming signal) is generated according to the calculated target driving current, and this signal is output to the corresponding light-emitting chip 21 in the backlight module. The light-emitting chip 21 is driven to emit light according to the target driving current, ensuring that the actual emitted brightness after passing through each optical film layer remains consistent with the initial design brightness. Because this embodiment uses a timing controller to compensate and correct the initial driving current, the actual emitted brightness after passing through each optical film layer of the backlight module is ensured. Compared with the initial design brightness Maintaining consistency ensures the stability of the white balance and the accuracy of the colors in the displayed image.

[0158] Furthermore, to achieve the above objectives, this embodiment also proposes a preparation method, referring to... Figure 11 , Figure 11 This is a schematic flowchart of the first embodiment of the preparation method of this application. Figure 11 As shown, in this embodiment, the method is used to prepare the backlight module as described above, and the method includes: Step S10: Obtain the back plate 1 and the lamp plate 2, and fix the lamp plate 2 on one side of the back plate 1; Step S20: Obtain the substrate 32 and form at least two microprism bodies 311 on one side surface of the substrate 32; Step S30: Using a mask, a dielectric film 312 is deposited sequentially on the surface of each of the microprism bodies 311. The microprism body 311 with the dielectric film 312 deposited is referred to as a microprism unit 31, and each of the microprism units 31 and the substrate 32 is referred to as a microprism film 3. Each microprism body 311 corresponds to a light-emitting chip 21. Step S40: Fix the microprism film 3 to the side of the lamp plate 2 away from the back plate 1 to obtain the backlight module.

[0159] It is understood that the aforementioned mask can be a thin metal plate used to selectively expose the target area and block non-target areas during the coating process, such as a perforated template made of Invar alloy (with an extremely low coefficient of thermal expansion). The aforementioned deposition can be a process of forming a thin film material on the surface of the microprism body 311, such as a vacuum coating process. The aforementioned fixing can be achieved by means of adhesive bonding, mechanical pressing, or frame support.

[0160] In a specific implementation, a backplate 1 and a lamp plate 2 can be provided. The lamp plate 2 is fixed to one side surface of the backplate 1, for example, by attaching the lamp plate 2 to the backplate 1 with thermally conductive adhesive, so that the heat generated by the lamp plate 2 can be conducted outward through the backplate 1.

[0161] Next, a transparent substrate 32 can be provided, and at least two microprism bodies 311 are formed on one side surface of the substrate 32 by an imprinting process. The number and arrangement of the microprism bodies 311 correspond one-to-one with the number and arrangement of the light-emitting chips 21 on the lamp board 2.

[0162] After the microprism body 311 is formed, a mask can be placed over the surface of the microprism film 3. The cutout windows on the mask can expose only the area of ​​one type of microprism body 311 (e.g., the microprism body 311 corresponding to red light), while the other microprism bodies 311 are blocked by the mask. Next, the microprism film 3 covered with the mask is placed in a vacuum deposition apparatus, and a corresponding dielectric film 312 (e.g., a red light-optimized dielectric film 312) is deposited on the exposed surface of the microprism body 311. After deposition, the mask is removed, completing the first zoned deposition.

[0163] Then, a second mask can be placed over the surface of the microprism film 3. The cutout window of this mask only exposes the area of ​​another microprism body 311 (e.g., the microprism body 311 corresponding to green light), and the above coating process is repeated. This process continues until the surface of all microprism bodies 311 has been deposited with their respective dielectric films 312. The microprism bodies 311 with deposited dielectric films 312 can then be referred to as microprism units 31, and each microprism unit 31 and the substrate 32 constitute the complete microprism film 3.

[0164] Finally, the microprism film 3 can be fixed to the side of the lamp plate 2 away from the back plate 1, so that each microprism unit 31 is aligned with the corresponding light-emitting chip 21 in the vertical direction to obtain a backlight module.

[0165] Considering that the alignment accuracy between the microprism body 311 and the light-emitting chip 21 directly affects the optical performance of the backlight module during the actual manufacturing process, in the above-mentioned step of fixing the microprism film 3 to the lamp board 2, the alignment marks on the edge of the microprism film 3 and the alignment marks on the edge of the lamp board 2 can be used for CCD visual alignment, so that the alignment accuracy between the microprism film 3 and the lamp board 2 is controlled within ±15μm.

[0166] Since this embodiment deposits a corresponding dielectric film 312 on the surface of each microprism body 311 through a mask partitioning coating process, microprism units 31 of different colors can obtain their own optimized spectrally selective film layers. Furthermore, the partitioning coating process is compatible with existing roll-to-roll imprinting and vacuum coating processes, making it suitable for large-scale mass production.

[0167] Furthermore, in order to form the aforementioned gradient layer 313, in this embodiment, the step of referring to the microprism body 311 on which the dielectric film 312 is deposited as a microprism unit 31 includes: Step S31: Coat the side of the dielectric film 312 opposite to the microprism body 311 with nanoimprint resin; Step S32: Imprint the nanoimprint resin using a nano grating mold, and then cure the imprinted nanoimprint resin to obtain a gradient layer 313. Step S33: The microprism body 311 with the gradient layer 313 and the dielectric film 312 deposited thereon is referred to as microprism unit 31.

[0168] It should be understood that the aforementioned nanoimprint resin can be a photocurable resin suitable for nanoimprinting processes, such as a UV-curable nanoimprint adhesive. The aforementioned nanograting mold can be an imprinting template with nanoscale raised and recessed patterns on its surface, such as a template made of silicon or nickel material with a subwavelength grating pattern. The aforementioned curing can be a process that transforms the resin from a liquid or semi-solid state to a solid state, such as UV curing or thermal curing.

[0169] In a specific implementation, after depositing a dielectric film 312 on the surface of the microprism body 311, a nanoimprint resin is coated on the side of the dielectric film 312 facing away from the microprism body 311. The coating thickness of the nanoimprint resin is determined according to the depth of the desired gradient layer 313, for example, the coating thickness is 80nm to 150nm.

[0170] Next, a nanograting mold can be obtained. The surface of the nanograting mold can have a nanoscale convex-concave pattern that is complementary to the desired grating structure (i.e., the protrusions of the mold correspond to the grooves of the grating, and the grooves of the mold correspond to the protrusions of the grating). The nanograting mold is imprinted onto the surface of a nanoimprinting resin, so that the nanoimprinting resin fills the grooves of the mold, forming a periodic convex-concave profile on the surface of the nanoimprinting resin.

[0171] While maintaining the imprinting pressure, the nanoimprinting resin is cured, for example, by using ultraviolet light irradiation to induce a cross-linking reaction and cure it into shape. After curing, the nanograting mold can be separated from the cured nanoimprinting resin for demolding. The surface of the nanoimprinting resin then replicates a nanograting pattern complementary to the mold, forming a gradient layer 313. The microprism body 311 with the gradient layer 313 and the deposited dielectric film 312 is referred to as the microprism unit 31.

[0172] It is important to emphasize that, for microprism bodies 311 of different colors, the nano-grating molds used when coating with nanoimprint resin can have different grating period parameters. For example, the mold period for red light is 580nm, for green light it is 480nm, and for blue light it is 400nm, thus giving each color-corresponding gradient layer 313 its own optimized grating period. Since this embodiment forms a gradient layer 313 on the outside of the dielectric film 312 by coating the surface of the dielectric film 312 with nanoimprint resin and performing nanoimprinting and curing, and the manufacturing process of the gradient layer 313 is compatible with existing nanoimprinting processes, it is suitable for large-scale mass production. Simultaneously, the gradient layer 313 can effectively reduce Fresnel reflection loss when light travels from the dielectric film 312 to the air.

[0173] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A backlight module, characterized in that, The backlight module includes: Back panel; A light panel is disposed on one side of the back panel, and at least two different colors of light-emitting chips are arranged on the light panel; A microprism film is disposed on the side of the lamp panel away from the back plate, and includes at least two microprism units. Each microprism unit corresponds to one of the light-emitting chips. Each microprism unit includes a microprism body and a dielectric film disposed on the microprism body. The microprism body is used to refract and deflect the first light emitted by the light-emitting chip of the corresponding color to the corresponding target angle to obtain the second light. The dielectric film is used to transmit the second light of the corresponding color to obtain a backlight source.

2. The backlight module as described in claim 1, characterized in that, The cross-section of the microprism body is triangular.

3. The backlight module as described in claim 2, characterized in that, The microprism body has a light-incident surface facing the lamp panel and two light-exit surfaces facing away from the lamp panel. The two light-exit surfaces are the two legs of the triangle, and the included angle between the two light-exit surfaces forms the vertex angle of the triangle. The triangle is an isosceles triangle, and the vertex angle of the microprism body corresponding to a specific color is... ; in, The center wavelength of the first light ray corresponding to the color of the microprism body. The microprism body at its center wavelength is The refractive index at that point, The target angle of the first ray of the corresponding color.

4. The backlight module as described in claim 1, characterized in that, The dielectric film includes several first material layers and several second material layers, wherein the refractive index of the first material layer is higher than that of the second material layer. The first material layer and the second material layer are alternately stacked.

5. The backlight module as described in claim 1, characterized in that, Each of the aforementioned microprism units further includes a gradient layer; The gradient layer is disposed on the side of the dielectric film opposite to the microprism body; The gradient layer is used to output a third ray after the second ray of the corresponding color is refracted at least twice between the dielectric film and the air through at least two different equivalent refractive indices. In this process, at least twice the equivalent refractive index gradually changes from the refractive index of the dielectric film to the refractive index of the air.

6. The backlight module as described in claim 5, characterized in that, The gradient layer is a grating structure, and the period of the grating structure corresponding to the color is... ; in, The period of the grating structure corresponding to the color. This is the subwavelength margin factor. The center wavelength of the second ray corresponding to the color, Let be the refractive index of the air.

7. The backlight module as described in claim 6, characterized in that, The depth of the grating structure is hc, and the duty cycle is fc. In the grating structure, the period is When the depth is hc and the duty cycle is fc, the corresponding objective function value is minimized. The objective function is: in, The value of the objective function. The incident angle of the first light ray to the corresponding microprism body. The incident angle The corresponding preset viewpoint weight coefficients, The transmittance of the red third ray output by the grating structure. The transmittance of the third green ray output by the grating structure. The transmittance of the blue third ray output by the grating structure. The preset average transmittance weighting coefficient, The average transmittance of the c-th color within the preset evaluation angle range.

8. A display, characterized in that, The display includes a display panel, a timing controller, and a backlight module as described in any one of claims 1 to 7, wherein the backlight module is disposed on the back side of the display panel, and the timing controller is electrically connected to the backlight module. The timing controller is used to output display signals to the backlight module; The backlight module is used to provide a backlight source to the display panel according to the display signal.

9. The display as claimed in claim 8, characterized in that, The timing controller is also used to acquire color information of the display screen and determine the target brightness ratio of each pixel according to the preset white balance target and the color information. The pixel includes light-emitting chips of at least two different colors. The timing controller is also used to acquire the characteristic curves of each of the light-emitting chips, and to back-calculate the initial driving current that satisfies the target brightness ratio based on each of the characteristic curves. The timing controller is also used to obtain the actual transmittance of the backlight module for each color, and to obtain the corresponding target driving current according to the preset conversion factor, the actual transmittance of each color and the corresponding initial driving current. The timing controller is also used to output a corresponding display signal to the backlight module according to the corresponding target drive current.

10. A preparation method, characterized in that, The method is used to prepare a backlight module as described in any one of claims 1 to 7, the method comprising: Obtain the back plate and the light panel, and fix the light panel to one side of the back plate; Obtain a substrate and form at least two microprism bodies on one side surface of the substrate; A dielectric film is sequentially deposited on the surface of each microprism body using a mask. The microprism body with the dielectric film deposited is referred to as a microprism unit, and each microprism unit and the substrate are referred to as a microprism film. Each microprism body corresponds to a light-emitting chip. The microprism film is fixed to the side of the lamp panel away from the back panel to obtain the backlight module.

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