Disclosure of Invention
In view of the above, an objective of the present invention is to provide a μ LED backlight for mixing light by using a dual-concave diffusion unit structure and a manufacturing method thereof, in which the dual-concave diffusion unit structure reduces the usage of functional films and the overall thickness of the backlight.
The invention is realized by adopting the following scheme: a uLED backlight source for mixing light by utilizing a double-concave diffusion unit structure comprises more than one light-emitting unit, wherein each light-emitting unit sequentially comprises an electrode substrate, a mu LED, a double-concave diffusion light guide plate, a scattering particle shallow coating and a quantum dot slurry coating from bottom to top;
the lower concave surface of the double-concave diffusion light guide plate is covered above the mu LED, and the upper concave surface of the double-concave diffusion light guide plate is sequentially filled with the scattering particle shallow coating and the quantum dot slurry coating.
Furthermore, the electrode substrate is of a three-layer structure and sequentially comprises a negative electrode thin layer, an insulating substrate and an addressing electrode from bottom to top; and an electrode through hole is formed in the substrate, and a negative electrode conductive metal material is filled in the electrode through hole, so that the mu LED can be electrically connected with the negative electrode thin layer.
Furthermore, the upper concave surface and the lower concave surface of the double-concave diffusion light guide plate have different curvature radiuses, and the curvature radius r of the lower concave surface1The single mu LED can be embedded into the concave layer, and the mu LEDs of the adjacent light-emitting units are isolated; radius of curvature r of upper concave surface2The 1/2 brightness part of the divergence light spot of the mu LED passing through the lower concave surface is lower than the end surface of the concave surface structure, and r is1>r2。
Further, the filling positions of the scattering particle shallow plating layer in the upper concave surface of the double-concave structure diffusion light guide plate are as follows: filling 1/2 brightness of the light spot diverged on the upper concave surface after the mu LED passes through the lower concave surface.
Further, the quantum dot slurry coating continues to be filled into the upper inner concave surface of the double-concave-structure diffusion light guide plate after the scattering particle shallow coating to the end surface, and a flat film is formed.
Further, in a light emitting cell, the thickness D of the light-scattering particle coating layerPowder medicineThe method comprises the following steps:
step S1: the total thickness of the double-concave diffusion light guide plate is H, the thickness of a single mu LED is d, the width of the single mu LED is W, the diameter of an opening of a concave surface of the light guide plate is W, and the curvature radius of an upper concave surface is r2The radius of curvature of the lower concave surface is r1,r1>r2(ii) a Dividing the light guide plate into an upper concave lens unit and a lower concave lens unit to determine parameters;
step S2: on the central section of the light guide plate, the intersection point of the upper surface of the scattering particle shallow coating and the upper concave surface is A, the external circle center of the upper concave surface is O, and the upper concave surface is arrangedThe central point of the concave surface is B, the included angle theta between OA and the opening end of the upper concave lens2Comprises the following steps:
the included angle between OA and OB is theta'2The thickness of the light coating of scattering particles satisfies the following formula:
Dpowder medicine=r2-r2cosθ′2;
The distance from the concave center point B of the upper concave surface to the center of the section of the light guide plate is as follows:
finding out an angle alpha when the brightness decays to be half of the central light intensity according to the cosine scattering rule of the light emitted by the mu LED;
step S3: the intersection of the mu LED radiation attenuation angle direction and the curved surface of the upper concave lens is the height of the filling section of the scattering particle shallow coating, and the function meets the following conditions by utilizing a trigonometric function relation:
i.e. angle of'2Satisfies the following conditions:
at the moment, according to intersection point A and included angle theta 'of the scattering particle shallow plating layer and the upper concave surface'2I.e. the thickness D of the coating of the scattering particles can be determinedPowder medicine。
Furthermore, the refractive index of the double-concave-structure diffusion light guide plate is greater than that of air, and the thickness of the double-concave-structure diffusion light guide plate is 0.3-2.5 mm.
Furthermore, the material adopted by the scattering particle shallow coating adopts inorganic scattering particles or organic scattering particles; wherein the inorganic scattering particles comprise silicon dioxide or titanium dioxide; wherein the organic scattering particles comprise PMMA, or PC material.
Further, the material of the quantum dot slurry coating is selected from II-VI compounds or III-V compounds, and is an inorganic compound or an organic compound.
The invention also provides a manufacturing method of the uLED backlight source for mixing light by using the double-concave diffusion unit structure, which specifically comprises the following steps:
step S1: manufacturing an electrode through hole in each light-emitting unit on an electrode substrate in a laser ablation or mechanical punching mode, depositing a conductive metal layer on the back of the substrate in an evaporation mode to form a negative electrode thin layer, filling a negative electrode conductive metal material into the electrode through hole, coating the conductive material on the front of the electrode substrate, and obtaining addressing electrodes distributed in a checkerboard shape by an etching method;
step S2: the mu LEDs are in one-to-one correspondence with the through holes of the addressing electrodes and the negative electrodes in a transfer or growth mode, scattering particle shallow coating materials are filled on the diffusion light guide plate with the double-concave structure in an evaporation or spraying mode to 1/2 brightness positions of light spots diffused by the mu LEDs after passing through the lower inner concave surface, and then quantum dot slurry is filled on the end surface of the upper inner concave surface in a blade coating mode to enable the upper surface of the light guide plate to be smooth, so that a mu LED array is obtained;
step S3: through assembly, the light guide plate corresponds to the mu LED array, the lower inner concave surface of the light guide plate in each light-emitting unit becomes a dome of the mu LED, and adjacent mu LEDs are blocked to form an independent unit.
Compared with the prior art, the invention has the following beneficial effects: the biconcave diffusion unit structure of the special-shaped light guide plate has the function of diffusing light, and can couple mu LED light in the diffusion unit with surface light sources formed by surrounding mu LEDs; the scattering particle coating enables light in a region with higher central light intensity of the mu LED to be scattered to an annular peripheral region with weaker light intensity, so that the light intensity of circular planar light spots emitted by each diffusion unit structure is uniformly distributed; the filling of the quantum dot slurry coating enables the color gamut range of the backlight source to be larger, and the problems of yield and consistency of light emitting wavelength of mu LEDs in the display field are solved on the basis of using the mu LEDs with the same specification as the backlight; the addressing electrode can enable the backlight source to have a local dimming function, the mu LED backlight source for mixing light by utilizing the double-concave diffusion unit structure simultaneously reduces the use of functional films, and the overall thickness of the backlight source is reduced.
Detailed Description
The invention is further explained below with reference to the drawings and the embodiments.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As shown in fig. 3, the present embodiment provides a uuled backlight source for mixing light by using a double-concave diffusion unit structure, which includes more than one light emitting unit, each light emitting unit includes, from bottom to top, an electrode substrate, a μ LED, a double-concave diffusion light guide plate, a shallow scattering particle plating layer, and a quantum dot paste plating layer;
the lower concave surface of the double-concave diffusion light guide plate is covered above the mu LED, and the upper concave surface of the double-concave diffusion light guide plate is sequentially filled with the scattering particle shallow coating and the quantum dot slurry coating.
The conductive electrode substrate is a substrate layer plated with an address electrode material subjected to graphical etching and is connected with the negative electrode through the through hole, and the address electrode can enable the backlight source to have a local dimming function; each unit concave diffusion structure of the double-concave unit structure diffusion light guide plate corresponds to one mu LED, and the concave structure can isolate adjacent mu LEDs at the same time so as to prevent light crosstalk; the shallow coating scattering particles only fill part of the upper concave diffusion structures, and the whole coating is a quasi-normal curve film, so that light in a region with higher central light intensity of the mu LED is scattered to an annular peripheral region with weaker light intensity, and the light intensity distribution of circular planar light spots emitted by each diffusion unit structure is uniform.
In this embodiment, the electrode substrate has a three-layer structure, and sequentially includes, from bottom to top, a negative electrode thin layer, an insulating substrate, and address electrodes formed by etching and distributed in a checkerboard shape; and an electrode through hole is formed in the substrate, and a negative electrode conductive metal material is filled in the electrode through hole, so that the mu LED can be electrically connected with the negative electrode thin layer.
Preferably, in this embodiment, the μ LED is a blue LED with a central wavelength of 440nm to 460nm and a half-peak width of 15nm to 40nm or a blue μ LED using an optical excitation type quantum dot coating, different excitation light sources are matched with different quantum dot slurry coatings in the upper concave structure, and the μ LED transfer should be grown on the electrode substrate in a one-to-one correspondence with the addressing electrode or by etching growth combination.
In this embodiment, the upper concave surface and the lower concave surface of the double-concave diffusion light guide plate have different curvature radiuses, and the curvature radius r of the lower concave surface1The single mu LED can be embedded into the concave layer, and the mu LEDs of the adjacent light-emitting units are isolated; radius of curvature r of upper concave surface2The mu LED can be diffused after passing through the lower concave surface1/2 of the light spot is lower than the end face of the concave structure, and r1>r2。
The material of the double concave-structure diffusion light guide plate can be an organic material, and comprises one or more of Polyethylene (PE), polypropylene (PP), polyethylene naphthalate (PEN), Polycarbonate (PC), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), Cellulose Acetate Butyrate (CAB), siloxane, polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyethylene terephthalate (PET), modified polyethylene terephthalate (PETG), Polydimethylsiloxane (PDMS) or cycloolefin copolymer (COC); or using inorganic materials including one or more of glass, quartz and transmissive ceramic materials.
In this embodiment, the filling positions of the scattering particle shallow plating layer in the upper concave surface of the double-concave structure diffusion light guide plate are as follows: filling 1/2 brightness of the light spot diverged on the upper concave surface after the mu LED passes through the lower concave surface.
In this embodiment, the quantum dot paste coating layer continues to fill the inner concave surface of the double concave diffusion light guide plate to the end surface after the scattering particle shallow coating layer, so as to form a flat film.
In this embodiment, the thickness D of the light-scattering particle layer in a light-emitting unitPowder medicineThe method comprises the following steps:
step S1: the total thickness of the double-concave diffusion light guide plate is H, the thickness of a single mu LED is d, the width of the single mu LED is W, the diameter of an opening of a concave surface of the light guide plate is W, and the curvature radius of an upper concave surface is r2The radius of curvature of the lower concave surface is r1,r1>r2(ii) a Dividing the light guide plate into an upper concave lens unit and a lower concave lens unit to determine parameters;
step S2: on the central section of the light guide plate, if the intersection point of the upper surface of the scattering particle shallow coating and the upper concave surface is A, the external circle center of the upper concave surface is O, and the central point of the concave surface of the upper concave surface is B, the included angle theta between the OA and the open end of the upper concave lens is2Comprises the following steps:
the included angle between OA and OB is theta'2The thickness of the light coating of scattering particles satisfies the following formula:
Dpowder medicine=r2-r2cosθ′2;
The distance from the concave center point B of the upper concave surface to the center of the section of the light guide plate is as follows:
finding out an angle alpha when the brightness decays to be half of the central light intensity according to the cosine scattering rule of the light emitted by the mu LED;
step S3: the intersection of the mu LED radiation attenuation angle direction and the curved surface of the upper concave lens is the height of the filling section of the scattering particle shallow coating, and the function meets the following conditions by utilizing a trigonometric function relation:
i.e. angle of'2Satisfies the following conditions:
at the moment, according to intersection point A and included angle theta 'of the scattering particle shallow plating layer and the upper concave surface'2I.e. the thickness D of the coating of the scattering particles can be determinedPowder medicine。
In this embodiment, the refractive index of the double-concave structured diffusion light guide plate is greater than that of air, and the thickness of the double-concave structured diffusion light guide plate is 0.3-2.5 mm.
In this embodiment, the material used for the shallow scattering particle coating layer is inorganic scattering particles or organic scattering particles; wherein the inorganic scattering particles comprise silicon dioxide or titanium dioxide; wherein the organic scattering particles comprise PMMA, or PC material.
In the embodiment, the material of the quantum dot slurry coating is selected from II-VI compounds or III-V compounds, and is an inorganic compound or an organic compound. Preferably selecting silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, indium phosphide quantum dots and indium arsenide quantum dot materials; if the excitation light source mu LED is monochromatic blue light, the mass ratio of the red quantum dot coating material to the green quantum dot coating material is 1: 8 to 1: 16, if the excitation light source mu LED is matched with a quantum dot coating, the quantum dots in the slurry are different from the quantum dots matched with the mu LED, if the excitation light source mu LED is matched with the quantum dot coating, the coating slurry uses green quantum dots, otherwise, the coating slurry is red quantum dots, and the slurry is filled to the end face of the concave structure and overflows in a small amount to form a flat film.
The embodiment also provides a manufacturing method of the uuled backlight source for mixing light by using the double-concave diffusion unit structure, which specifically comprises the following steps:
step S1: manufacturing an electrode through hole in each light-emitting unit on an electrode substrate in a laser ablation or mechanical punching mode, depositing a conductive metal layer on the back of the substrate in an evaporation mode to form a negative electrode thin layer, filling a negative electrode conductive metal material into the electrode through hole, coating the conductive material on the front of the electrode substrate, and obtaining addressing electrodes distributed in a checkerboard shape by an etching method;
step S2: the mu LEDs are in one-to-one correspondence with the through holes of the addressing electrodes and the negative electrodes in a transfer or growth mode, scattering particle shallow coating materials are filled on the diffusion light guide plate with the double-concave structure in an evaporation or spraying mode to 1/2 brightness positions of light spots diffused by the mu LEDs after passing through the lower inner concave surface, and then quantum dot slurry is filled on the end surface of the upper inner concave surface in a blade coating mode to enable the upper surface of the light guide plate to be smooth, so that a mu LED array is obtained;
step S3: through assembly, the light guide plate corresponds to the mu LED array, the lower inner concave surface of the light guide plate in each light-emitting unit becomes a dome of the mu LED, and adjacent mu LEDs are blocked to form an independent unit.
In this embodiment, the diffusion light guide plate based on the μ LED backlight is subjected to microstructure design, and then a scattering particle plating layer and a quantum dot slurry plating layer are used in combination to form an integrated diffusion light-mixing backlight structure. The special-shaped light guide plate is a double-concave diffusion unit structure with regularly distributed upper and lower surfaces, the double-concave structure has a light diffusion function and can mutually couple mu LED light in the diffusion unit and surface light sources formed by surrounding mu LEDs; the concave diffusion structure of each unit in the light guide plate corresponds to one mu LED respectively, the concave structure can isolate adjacent mu LEDs to prevent light crosstalk, and the function of local dimming of the backlight source can be realized by matching the addressing electrode; the curvature radius of the upper concave diffusion structure of each unit in the light guide plate is smaller, namely the concave surface is deeper, a scattering particle coating layer which is similar to a normal curve as a whole is plated inside the concave surface, and the coating surface is lower than the end surface of the upper concave diffusion structure, so that the light of a central area with higher light intensity of the mu LED is scattered to an annular peripheral area with weaker light intensity, and the light intensity of circular surface-shaped light spots emitted by each diffusion unit structure is distributed uniformly; the filling of the quantum dot slurry coating enables the color gamut range of the backlight source to be larger, and the problems of yield and consistency of light emitting wavelength of mu LEDs in the display field are solved on the basis of using the mu LEDs with the same specification as the backlight; the dual-concave structure curvature parameters and the thickness of the scattering particle coating in the structure are reasonably matched, so that the illumination uniformity of a surface light source after light mixing through the light guide plate can be effectively improved, the use of a functional membrane is reduced by the mu LED backlight source for light mixing by using the dual-concave diffusion unit structure, and the overall thickness of the backlight source is reduced.
Next, the present embodiment further describes the structure and the manufacturing method described above with reference to fig. 1 to 3.
As shown in fig. 1, a negative electrode conductive through hole 101 required by a mu LED array is ablated on the back surface of an electrode substrate 2 (substrate material is Si) by means of laser ablation, an electrode substrate negative electrode thin layer 1 is deposited on a back plate by means of metal evaporation after the substrate is cooled, and an electrode material is deposited by using Ag until the through hole is completely filled; coating electrode materials on the front surface of an electrode substrate, obtaining row and column addressing electrodes in a checkerboard distribution mode through an etching method, carrying out spin coating shielding on the photoetching materials in a region where the mu LED is not grown by utilizing a photoetching process, realizing epitaxial growth of a low-temperature AlN layer on a Si substrate by adopting PLD (programmable logic device), growing GaN on a buffer layer AlN to form a mu LED array 4 (the specification of a single mu LED is 35um x 7um), connecting the positive electrode of the mu LED with the addressing electrodes after the growth is finished, and etching and removing the shielding materials;
as shown in FIG. 2, the curvature r of the upper and lower concave lenses of the double-concave diffusion unit is selected2,r1(,r1>r2) The light guide plate thickness is 300um, digs respectively on the upper and lower two sides of light guide plate and gets concave lens structure that fixed radius W is 80um and form light guide plate 5 that has biconcave diffusion cell structure, utilizes following conditional expression:
determining an included angle theta 'between an intersection point A of the scattering particle shallow plating layer 6 and the upper concave curved surface and the curvature radius of the upper concave lens'2And then, the formula is utilized: dPowder medicine=r2-r2cosθ′2And determining the thickness of the coating and filling the silicon dioxide scattering particles into the concave layer on the light guide plate to the position required by the calculated film thickness.
Blending the red CdSe quantum dot material and the green CdSe quantum dot material in a mass ratio of 1: 12, dissolving quantum dot slurry formed in an organic solvent, filling the residual space of the concave layer on the light guide plate with the quantum dot slurry and overflowing part, leveling by blade coating to form a quantum dot slurry coating 7, corresponding the light guide plate to the mu LED array, forming the concave layer of the light guide plate into a mu LED dome, separating adjacent mu LEDs to form an independent unit, and obtaining the mu LED backlight source with mixed light of a double-concave diffusion unit structure, wherein the assembled structure of one light emitting unit is shown in figure 3.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.