CN113820886A

CN113820886A - Display device

Info

Publication number: CN113820886A
Application number: CN202010570713.7A
Authority: CN
Inventors: 李富琳; 乔明胜; 张楠楠
Original assignee: Hisense Visual Technology Co Ltd
Current assignee: Hisense Visual Technology Co Ltd
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2021-12-21
Anticipated expiration: 2040-06-19
Also published as: CN113820886B

Abstract

The invention discloses a display device, comprising: the display panel and the miniature light-emitting diode lamp panel; the miniature light-emitting diode lamp panel comprises a circuit board and a miniature light-emitting diode; at least two micro light-emitting diodes are welded on at least one exposed bonding pad of the circuit board, and then the micro light-emitting diodes welded on the same bonding pad are in parallel connection; when the micro light-emitting diode fails on the bonding pad, as long as one micro light-emitting diode is normally welded and can normally emit light, the driving current can flow through the normal micro light-emitting diode, and meanwhile, the total light-emitting intensity is kept unchanged. From this, the maintenance probability of miniature emitting diode lamp plate can greatly reduced.

Description

Display device

Technical Field

The invention relates to the technical field of display, in particular to a display device.

Background

The liquid crystal display screen has the advantages of low power consumption, small volume, low radiation and the like as the current mainstream display screen. The liquid crystal display panel is a non-self-luminous panel and needs to be matched with a backlight module for use.

The micro Light Emitting Diode (Mini LED) has become a current hotspot in the liquid crystal display technology as a backlight, which is different from the traditional liquid crystal display backlight scheme adopting a side-in type Light guide plate, and a huge amount of Mini LEDs are adopted as the backlight source, so that not only can the backlight be thinned, but also more refined dynamic control can be realized, and the dynamic contrast of the liquid crystal display is improved.

In the Mini LED backlight display, since the Mini LED is small in size, a bonding error is inevitably caused during bonding, which may cause problems such as cold joint or continuous bonding, and thus the production yield may be reduced. However, after the Mini LED is soldered, a layer of protective glue is coated on the surface of the Mini LED, and then the protective glue on the Mini LED needs to be removed when the Mini LED is repaired, and the Mini LED is soldered again, so that the repair difficulty is increased.

Disclosure of Invention

In some embodiments of the present invention, the micro light emitting diode lamp panel includes a circuit board and micro light emitting diodes, at least two micro light emitting diodes are welded on at least one exposed pad of the circuit board, and then the micro light emitting diodes welded on the same pad are in a parallel connection relationship, when the micro light emitting diodes are welded normally, the micro light emitting diodes are driven in a shunt manner, and the total light emitting intensity of each micro light emitting diode corresponds to the driving circuit; when the micro light-emitting diode fails on the bonding pad, as long as one micro light-emitting diode is normally welded and can normally emit light, the driving current can flow through the normal micro light-emitting diode, and meanwhile, the total light-emitting intensity is kept unchanged. From this, the maintenance probability of miniature emitting diode lamp plate can greatly reduced.

In some embodiments of the invention, the circuit board comprises: the circuit comprises a base material, a circuit layer and a solder mask layer. The circuit layer includes a pad for soldering the micro light emitting diode, and the solder resist layer includes an opening for exposing at least a portion of the pad. At least two openings are arranged above the bonding pad, and the openings are used for welding the micro light-emitting diodes. Openings of the solder mask layers corresponding to the bonding pads are mutually separated and not communicated, so that the problems of continuous welding and the like when the micro light-emitting diodes are welded on the bonding pads can be avoided, and the micro light-emitting diodes welded on the same bonding pad are ensured to be mutually connected in parallel.

In some embodiments of the present invention, two bonding pads are exposed in each opening, and the two bonding pads are arranged in pairs for respectively bonding two electrodes of the micro light emitting diode. A gap with a certain distance exists between the two bonding pads, and the gap is not provided with a pattern of a circuit layer and used for blocking the two bonding pads, so that the problem of short circuit of the micro light-emitting diode is avoided.

In some embodiments of the invention, the solder mask is a protective layer positioned above the circuit board and has the function of diffuse reflection of incident light, so that light emitted by the panel of the micro light-emitting diode can be reflected to the light-emitting side again by the solder mask when being reflected to one side of the back plate by elements in the backlight module, thereby improving the utilization efficiency of the light source.

In some embodiments of the present invention, the material of the solder mask layer is white ink.

In some embodiments of the present invention, the thickness of the solder mask layer is controlled such that its reflectivity is greater than 95%.

In some embodiments of the present invention, the circuit board is rectangular, and the micro light emitting diode is also rectangular. Because the expansion and shrinkage of the circuit board in the long edge direction are larger, in order to ensure the welding yield of the micro light-emitting diode, the long edge of the micro light-emitting diode is arranged to be parallel to the short edge of the circuit board, and the short edge of the micro light-emitting diode is arranged to be parallel to the long edge of the circuit board.

In some embodiments of the present invention, the openings of the solder resist layer are rectangular in shape; the long side direction of the opening is parallel to the long side direction of the micro light-emitting diode, and the short side direction of the opening is parallel to the short side direction of the micro light-emitting diode; and the size of the opening is larger than that of the micro light-emitting diode.

In some embodiments of the invention, the packaging layer covers the surface of the side of the micro light-emitting diode, which is far away from the circuit board; the packaging layer is provided with mutually-separated patterns which correspond to the bonding pads one by one. At least two micro light-emitting diodes are welded on each bonding pad, and when the micro light-emitting diodes are packaged in a point packaging mode, a packaging layer can be formed on the surfaces of all the micro light-emitting diodes on one bonding pad, so that the micro light-emitting diodes on each bonding pad are packaged.

In some embodiments of the invention, a reflective sheet is disposed on a surface of the solder mask layer on a side close to the micro light-emitting diode. The reflector plate has higher reflectivity compared with a solder mask on the surface of the circuit board, and can improve the reflection efficiency of light to the light-emitting side, thereby improving the light extraction efficiency of the backlight module and the utilization rate of a light source.

In some embodiments of the invention, the micro light emitting diode lamp panel is partitioned, the micro light emitting diodes in each region can be controlled independently, wherein the bonding pads in each partition are connected in series, and the micro light emitting diodes on the bonding pads are connected in parallel. Even if the micro light-emitting diode fails, the problem that the whole broken circuit partition cannot be lightened can not be caused as long as one normal micro light-emitting diode is arranged on one bonding pad.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic cross-sectional structure diagram of a display device according to an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of a backlight module according to an embodiment of the invention;

FIG. 3 is a schematic diagram of a top view of the circuit board of FIG. 2;

fig. 4 is a schematic cross-sectional structure diagram of a circuit board according to an embodiment of the present invention;

fig. 5 is a schematic top view of a circuit board according to an embodiment of the present invention;

FIG. 6 is a second schematic cross-sectional view illustrating a backlight module according to an embodiment of the present invention;

FIG. 7 is a schematic top view of the micro LED lamp panel of FIG. 6;

FIG. 8 is a schematic circuit diagram of a micro light emitting diode in the prior art;

fig. 9 is a schematic circuit diagram of a micro light emitting diode according to an embodiment of the present invention.

The backlight module comprises a backlight module 100, a display panel 200, a backboard 11, a miniature light emitting diode lamp panel 12, a diffusion layer 13, an optical diaphragm 14, a circuit board 121, a miniature light emitting diode 122, a packaging layer 123, a reflector 124, a 1211 substrate, a 1212-circuit layer 1213-a solder resist layer, a p-pad and a k-opening.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, the present invention is further described with reference to the accompanying drawings and examples. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their repetitive description will be omitted. The words expressing the position and direction described in the present invention are illustrated in the accompanying drawings, but may be changed as required and still be within the scope of the present invention. The drawings of the present invention are for illustrative purposes only and do not represent true scale.

The liquid crystal display mainly comprises a backlight module and a liquid crystal display panel. The liquid crystal display panel does not emit light, and brightness display needs to be realized by a light source provided by the backlight module.

The display principle of the liquid crystal display is that liquid crystal is placed between two pieces of conductive glass, and the electric field effect of liquid crystal molecule distortion is caused by the driving of an electric field between two electrodes so as to control the transmission or shielding function of a backlight source, thereby displaying an image. If a color filter is added, a color image can be displayed.

Fig. 1 is a schematic cross-sectional structure diagram of a display device according to an embodiment of the present invention.

Referring to fig. 1, the display device includes: the backlight module 100 is used for providing backlight to the display panel 200, and the display panel 200 is used for displaying images.

The backlight module 100 is generally disposed at the bottom of the display device, and has a shape and size corresponding to those of the display device. When applied to the field of televisions or mobile terminals, the backlight module generally takes a rectangular shape.

The backlight module in the embodiment of the invention adopts the direct type backlight module, is used for uniformly emitting light rays in the whole light emitting surface, and provides light rays with sufficient brightness and uniform distribution for the display panel, so that the display panel can normally display images.

The display panel 200 is located at the light-emitting side of the backlight module 100, and the shape and size of the display panel are generally matched with those of the backlight module. In general, the display panel 200 may be configured in a rectangular shape including a top side, a bottom side, a left side and a right side, wherein the top side is opposite to the bottom side, the left side is opposite to the right side, the top side is connected to one end of the left side and one side of the right side, and the bottom side is connected to the other end of the left side and the other end of the right side.

The display panel 200 is a transmissive display panel, which can modulate the transmittance of light, but does not emit light by itself. The display panel 200 has a plurality of pixel units arranged in an array, and each pixel unit can independently control the transmittance and color of light incident to the pixel unit from the backlight module 100, so that the light transmitted by all the pixel units forms a displayed image.

A High-Dynamic Range (HDR) display technology can provide more Dynamic representations and image details, can better reflect the own visual effects of objects in a real environment, and is widely believed to cause the next revolution in the display field. Meanwhile, the HDR technology also puts higher demands on the liquid crystal display terminal, and realizes finer partition control and contrast.

Fig. 2 is a schematic cross-sectional structure view of a backlight module according to an embodiment of the invention.

Referring to fig. 2, along the light-emitting direction of the light in the backlight module, the backlight module sequentially includes: the backlight module comprises a back plate 11, a micro light-emitting diode lamp panel 12, a diffusion layer 13 and an optical diaphragm 14.

The back plate 11 is located at the bottom of the backlight module and has supporting and bearing functions. The back plate 11 is typically a square structure, the shape of which is adapted to the shape of the display device when applied to a profiled display device.

The back panel 11 in the embodiment of the present invention has a rectangular structure including a top side, a bottom side, a left side and a right side. Wherein the antenna side is opposite to the ground side, the left side is opposite to the right side, the antenna side is connected with one end of the left side and one side of the right side respectively, and the ground side is connected with the other end of the left side and the other end of the right side respectively.

The material of the back plate 11 is aluminum, iron, aluminum alloy or iron alloy. The back plate 11 is used for fixing the edge positions of the miniature light emitting diode lamp panel 12 and supporting and fixing optical films, diffusion plates and other components, and the back plate 11 also plays a role in heat dissipation of the miniature light emitting diode lamp panel 12.

The backlight module is a direct type backlight module, and the micro light emitting diode lamp panel 12 is located on the back plate 11 and serves as a backlight source. In general, the whole of the micro led lamp panel 12 may be square or rectangular, with a length of 200mm-800mm and a width of 100mm-500 mm.

According to the size of the display device, a plurality of miniature light-emitting diode lamp panels 12 can be arranged, and backlight is provided between the miniature light-emitting diode lamp panels 12 in a splicing mode. In order to avoid the optical problem caused by splicing the miniature light-emitting diode lamp panels 12, the splicing seams between the adjacent miniature light-emitting diode lamp panels 12 are as small as possible, and even seamless splicing is realized.

The micro light emitting diode means that the size of the traditional light emitting diode is reduced to below 500 mu m. When the size of the micro light-emitting diode is less than 50 μm, a high-density micro light-emitting diode array is formed on a circuit substrate, the pixel pitch can reach the micron level, and the display technology of active independent addressing and driving can be realized. When the size of the micro light emitting diode is between 100 μm and 300 μm, the micro light emitting diode can be applied to both application directions of the backlight and the display screen.

The Mini LED as the backlight becomes a current research focus in the liquid crystal display, and because the Mini LED chip is small in size, more Mini LEDs can be adopted as light sources in the backlight, so that the backlight thinning and more refined dynamic control can be realized, and the dynamic contrast of the liquid crystal display is improved.

The diffusion layer 13 is located on the light-emitting side of the micro led lamp panel 12. The diffusion layer 13 is entirely disposed on the light-emitting side of the micro led lamp panel 12, and the shape of the diffusion layer 13 is the same as that of the micro led lamp panel 12. The diffusion layer 13 may be provided in a rectangular or square shape in a general case.

The diffusion layer 13 functions to scatter incident light, making the light passing through the diffusion layer 13 more uniform. The diffusion layer 13 is provided with scattering particle materials, and light incident to the scattering particle materials can be refracted and reflected continuously, so that the effect of scattering the light is achieved, and the effect of light uniformization is achieved.

The diffusion layer 13 may take the form of a diffusion plate or a diffusion sheet. If the light source is applied to a large display device such as a television, a diffusion plate can be adopted; and when being applied to small-size display device such as cell-phone, intelligent bracelet, can adopt the diffusion piece.

The thickness of the diffusion plate is larger than that of the diffusion plate, and the thickness of the diffusion plate is 1.5mm-3 mm. The diffusion plate has higher haze and more uniform effect, and can be processed by an extrusion process, and the diffusion plate is made of at least one material selected from polymethyl methacrylate (PMMA), Polycarbonate (PC), polystyrene materials (PS) and polypropylene (PP).

The diffusion sheet has a thickness of 0.3mm or less, is relatively thin, and is more suitable for small and light display devices. The diffusion sheet is usually prepared by coating diffusion particles on a substrate, and the substrate may be polyethylene terephthalate PET, glass, or the like, and the diffusion particles may be titanium dioxide, zinc oxide, calcium oxide, or the like.

The optical film 14 is located on one side of the diffusion layer 13 departing from the miniature led lamp panel 12, the optical film 14 is arranged in a whole layer, and the shape of the optical film 14 is the same as that of the miniature led lamp panel 12, and the optical film can be arranged in a rectangular or square shape under normal conditions.

The optical film 14 can be disposed to adapt the backlight module to various practical applications.

When the micro led in the micro led lamp panel 12 is a blue micro led, the optical film 14 includes a quantum dot layer or a fluorescent layer.

The quantum dot layer comprises a red quantum dot material and a green quantum dot material, the red quantum dot material emits red light under the excitation of blue light, the green quantum dot material emits green light under the excitation of the blue light, and the red light, the green light and the transmitted blue light which are emitted by excitation are mixed to form white light for emitting.

The fluorescent layer comprises fluorescent materials which are stimulated to emit red light and green light, and the stimulated red light, the green light and the transmitted blue light are mixed into white light to be emitted.

In addition, the optical film 14 may further include a prism sheet, which can change the exit angle of light, thereby changing the viewable angle of the display device.

The optical film 14 may further include a reflective polarizer, which is a brightness enhancement film, and can improve the brightness of the backlight module, improve the utilization efficiency of light, and make the emergent light have polarization property, thereby omitting the use of the polarizer under the lcd panel.

Referring to fig. 2, the miniature led lamp panel 12 in the embodiment of the present invention includes: a circuit board 121, a micro light emitting diode 122, and an encapsulation layer 123.

The circuit board 121 is located on the back plate 11, and the shape of the circuit board 121 is the same as the overall shape of the micro led lamp panel 12. In general, the circuit board 121 has a plate shape, and has a rectangular or square shape as a whole. The length of the circuit board 121 is 200mm-800mm, and the width is 100mm-500 mm.

The Circuit Board 121 may be a Printed Circuit Board (PCB), or the Circuit Board 121 may also be an array substrate formed by manufacturing a thin film transistor driving Circuit on a substrate.

The substrate or substrate base of the circuit board 121 may be made of a flexible material to form a flexible display device.

The circuit board 121 is used for providing a driving electrical signal for the micro light emitting diode 122. The micro light emitting diode 122 and the circuit board 121 are separately manufactured, the surface of the circuit board 121 includes a plurality of bonding pads for soldering the micro light emitting diode 122, the micro light emitting diode 122 is transferred to the bonding pads after the manufacturing, and the micro light emitting diode 122 is soldered on the circuit board 121 through processes such as reflow soldering, so that the micro light emitting diode 122 can be driven to emit light by controlling an input signal of the circuit board 121.

The micro light emitting diodes 122 are located on the circuit board. The electrodes of the micro leds 122 are soldered to the exposed pads of the circuit board 121, so as to electrically connect the two.

The micro light emitting diode 122 is different from a general light emitting diode, and is specifically referred to as a micro light emitting diode chip. The small size of the micro-leds 122 is advantageous for controlling the dynamic light emission of the backlight module to a smaller sub-area, which is advantageous for improving the contrast of the image. In the present embodiment, the micro-leds 122 have a size of 50 μm to 300 μm.

The micro led lamp panel 12 may include only micro leds of one color, and may also include micro leds of multiple colors, which is not limited herein.

The packaging layer 123 covers the surface of the micro light emitting diode 122 on the side away from the circuit board 121. The encapsulating layers 123 may be provided separately from each other or may be provided in a single layer. When the two layers are separately arranged, the packaging layer 123 only covers the surface of the micro light-emitting diode 122, and no pattern is arranged in other areas of the circuit board; when the whole layer is disposed, the encapsulation layer 123 covers the whole circuit board 121 and the surface of the micro light emitting diode 122.

The encapsulation layer 123 is used to protect the micro light emitting diode 122 and prevent foreign matters from entering the micro light emitting diode 122. In the embodiment of the present invention, the encapsulation layer 123 may be made of a transparent colloid material, such as silicon gel or epoxy resin. The encapsulation layer 123 can be formed by spot coating or full-surface coating.

The circuit board 121 and the micro leds 122 are usually prepared separately, and the micro leds 122 need to be transferred to the circuit board 121 to be prepared into the micro led lamp panel 12 by soldering.

Firstly, the solder paste is printed on the circuit board 121, and usually, the solder paste is printed through a steel mesh, and an opening is formed in the steel mesh at a position corresponding to the pad for soldering the Mini LED, and then the solder paste falls on the pad of the circuit board 121 through the opening of the steel mesh in the process of printing the solder paste. Then, the micro light emitting diode 122 is transferred to a bonding pad of the circuit board 121, and after being heated at a high temperature in a reflow furnace, the solder paste is melted and then solidified, and the micro light emitting diode 122 is soldered on the circuit board 121 through the solder paste.

In the soldering process of the micro led 122, the position of the pad is shifted due to the expansion and contraction of the circuit board 121, and at this time, the edge of the micro led 122 may be lapped on the non-conductive layer at the edge of the pad, which is prone to poor problems such as cold joint or solder joint.

However, the micro light emitting diode 122 is covered with an encapsulation layer after being soldered, and if the micro light emitting diode 122 is disconnected or does not emit light due to poor soldering, the encapsulation layer on the surface of the micro light emitting diode 122 needs to be removed and then soldered again, which makes the repair difficult.

Fig. 3 is a schematic top view of the circuit board in fig. 2, and referring to fig. 2 and fig. 3, in order to improve the soldering yield of the micro light emitting diodes and reduce the maintenance probability of the micro light emitting diodes, the circuit board 121 in the embodiment of the present invention includes pads p for soldering the micro light emitting diodes 122, and at least two micro light emitting diodes 122 are soldered on at least one of the pads p.

At least two micro light-emitting diodes 122 are welded on at least one exposed bonding pad of the circuit board 121, so that the micro light-emitting diodes 122 welded on the same bonding pad are in parallel connection, when the micro light-emitting diodes 122 are welded normally, the micro light-emitting diodes 122 are driven in a shunt manner, and the total luminous intensity of each micro light-emitting diode 122 corresponds to the driving circuit; when the micro light emitting diode 122 on the bonding pad has a fault, as long as one micro light emitting diode is welded normally and can emit light normally, the driving current can flow through the normal micro light emitting diode 122, and meanwhile, the total light emitting intensity is guaranteed to be kept unchanged. Therefore, the maintenance probability of the miniature LED lamp panel 12 can be greatly reduced.

If the failure probability of a single micro led 122 is 0.01%, the failure probability of soldering two micro leds 122 on each pad can be reduced to 0.0001% by using the structure of the embodiment of the present invention.

In the embodiment of the invention, at least two micro light-emitting diodes 122 can be welded on the welding disc of a partial area of the circuit board, so that the maintenance probability of the partial area can be reduced, and the area can correspond to the core display area of the display device, thereby ensuring that the yield of the core display area of the display device is higher. In addition, all the pads on the circuit board can be welded with at least two micro light emitting diodes 122, so that the maintenance probability of the whole micro light emitting diode lamp panel 12 can be reduced.

Fig. 4 is a schematic cross-sectional structure diagram of a circuit board according to an embodiment of the present invention.

Referring to fig. 4, the circuit board 121 in the embodiment of the present invention includes: substrate 1211, wiring layer 1212, and solder resist layer 1213.

The substrate 1211 is a substrate of the circuit board 121 and has supporting and bearing functions. The shape of the substrate 1211 determines the overall shape of the circuit board 121, and the substrate 1211 is generally square or rectangular. The substrate 1211 includes a top side, a bottom side, a left side, and a right side. Wherein the antenna side is opposite to the ground side, the left side is opposite to the right side, the antenna side is connected with one end of the left side and one side of the right side respectively, and the ground side is connected with the other end of the left side and the other end of the right side respectively.

The substrate 1211 may be made of flame retardant materials such as FR-4 board and CEM-3 board, aluminum substrate, glass substrate, or flexible material such as polyimide or polyester film, and is not limited herein.

The circuit layer 1212 is disposed on the substrate 1211; the circuit layer 1212 is formed by coating a conductive material such as copper on the substrate 1211, and forming a pattern of a driving circuit by an etching process, wherein the circuit layer 1212 can transmit a driving signal for driving the micro light emitting diode 122 connected to the circuit layer 1212 to emit light.

Referring to fig. 4, the circuit layer 1212 includes a pad p for soldering the micro light emitting diode 122, and the micro light emitting diode 122 may be electrically connected to the circuit board 121 by soldering an electrode of the micro light emitting diode 122 to the pad p of the circuit layer 1212.

Solder mask 1213 covers the surface of circuit layer 1212 facing away from substrate 1211, and solder mask 1213 is used to protect circuit layer 1212 from insulation. The solder resist layer 1213 has the same shape as the circuit board 121. The solder resist layer 1213 may be coated with an insulating material over the wiring layer 1212 and formed with an opening exposing the pad p.

Fig. 5 is a schematic top view of a circuit board according to an embodiment of the present invention.

Referring to fig. 5, the solder resist layer 1213 in the embodiment of the present invention includes openings k for exposing at least a portion of the pads, each of the pads p has at least two openings k separated from each other, and one micro light emitting diode 122 is soldered to the pad p in each of the openings k.

At least two openings are provided above the bonding pads p, the openings being used for soldering the micro light emitting diodes 122. Openings k of the solder resist layers 1213 corresponding to the pads p are separated and not communicated with each other, so that problems such as continuous welding and the like caused when the micro light-emitting diodes 122 are welded on the pads p can be avoided, and the micro light-emitting diodes welded on the same pad p are ensured to be connected in parallel.

Referring to fig. 5, two pads p are exposed in each opening k, and the two pads p are disposed in pairs for soldering two electrodes of the micro light emitting diode 122, respectively. A gap with a certain distance exists between the two bonding pads p, and the pattern of the circuit layer 1212 is not arranged at the gap, so that the two bonding pads are blocked, and the problem of short circuit of the micro light emitting diode 122 is avoided.

Solder mask 1213 is the protective layer that is located the circuit board top, still has the effect to incident light diffuse reflection simultaneously, and when the light that miniature emitting diode lamp plate 122 outgoing was reflected back to backplate one side by the component in the backlight unit like this, can be reflected to light-emitting one side again by solder mask 1213, improves the utilization efficiency of light source from this.

The solder resist layer 1213 can be made of a material with light reflection property such as white ink (white oil for short), and the reflectivity of the solder resist layer 1213 can be changed by adjusting the thickness of the white oil, in the embodiment of the invention, the reflectivity of the solder resist layer 1213 is greater than 95%, so that the utilization rate of light of a light source can be improved.

Referring to fig. 5, in the embodiment of the present invention, the circuit board is rectangular, and the micro light emitting diode 122 is also rectangular. Referring to fig. 5, the long sides of the circuit board are parallel to the x-direction and the short sides of the circuit board are parallel to the y-direction. Because the expansion and contraction amount of the circuit board in the long side direction x is larger, in order to ensure the welding yield of the micro light-emitting diode 122, the long side of the micro light-emitting diode 122 is arranged to be parallel to the short side of the circuit board, and the short side direction of the micro light-emitting diode 122 is arranged to be parallel to the long side direction of the circuit board.

Referring to fig. 5, in the present column, the opening k of the solder resist layer 1213 is rectangular in shape; the long side direction of the opening k is parallel to the long side direction of the micro light emitting diode 122, and the short side direction of the opening k is parallel to the short side direction of the micro light emitting diode 122; and the size of the opening k is larger than that of the micro light emitting diode 122.

Since the micro light emitting diode 122 needs to be soldered to the pad p in the opening k, the shape of the opening k of the solder resist layer is generally the same as the shape of the micro light emitting diode 122, and the arrangement directions of the opening k and the long side and the short side of the micro light emitting diode 122 are also the same.

The expansion and contraction amount of the circuit board in the long side direction x is relatively large, so that the offset of the bonding pad p along with the circuit board is relatively large, and the long side direction x of the circuit board is parallel to the short side direction of the micro light-emitting diode 122, so that the length of the opening k parallel to the short side direction of the micro light-emitting diode 122 is set to be 1.3-1.7 times of the length of the short side of the micro light-emitting diode 122, and the micro light-emitting diode 122 can be ensured to fall in the range of the opening k in the short side direction in the welding process.

The expansion and contraction amount of the circuit board in the short side direction y is relatively small, so that the offset of the bonding pad p along with the circuit board is relatively small, the short side direction y of the circuit board is parallel to the long side direction of the micro light-emitting diode 122, therefore, the length of the opening k parallel to the long side direction of the micro light-emitting diode 122 is set to be 1.1-1.4 times of the length of the long side of the micro light-emitting diode 122, and the micro light-emitting diode 122 can be ensured to fall in the range of the opening k in the long side direction in the welding process.

When the micro light emitting diode 122 is packaged by using the packaging adhesive, two forms of dispensing and whole layer gluing can be adopted. The glue dispensing and packaging mode can save packaging glue materials and reduce the cost; and the whole layer of gluing mode has higher packaging efficiency.

Fig. 6 is a second schematic cross-sectional view of a backlight module according to an embodiment of the invention.

Referring to fig. 6, a packaging layer 123 of the micro led lamp panel 12 covers a surface of the micro led 122 on a side away from the circuit board 121; the package layer 123 has mutually discrete patterns in one-to-one correspondence with the pads p.

In the embodiment of the present invention, at least two micro light emitting diodes 122 are welded on the bonding pads p, and when the micro light emitting diodes 122 are packaged in a dot packaging manner, the packaging layer 123 may be formed on the surfaces of all the micro light emitting diodes 122 on one bonding pad p, so as to package the micro light emitting diodes on each bonding pad.

In order to improve the reflectivity of the micro led lamp panel 12, referring to fig. 6, in the embodiment of the invention, a reflective sheet 124 is further disposed on the surface of the solder mask layer on the side close to the micro led 122. The reflection sheet 124 has a higher reflectivity than a solder resist layer on the surface of the circuit board, and can improve the reflection efficiency of light to the light-emitting side, thereby improving the light extraction efficiency of the backlight module and the utilization rate of the light source.

Fig. 7 is a schematic top view of the micro led lamp panel shown in fig. 6.

Referring to fig. 7, the reflective sheet 124 includes an opening for exposing the pattern of the encapsulation layer 123. The shape of the encapsulation layer 123 is naturally formed by dispensing glue on the surface of the micro light emitting diode 122 and then performing diffusion, curing, etc., and the outer contour is generally similar to a circle, so the openings of the reflective sheet 124 may be set to be circular, the positions of the openings correspond to the patterns of the encapsulation layer 123 one by one, and the size of the openings is slightly larger than the size of the patterns of the encapsulation layer 123.

In the embodiment of the present invention, the micro light emitting diode lamp panel 12 may be partitioned, and the micro light emitting diodes 122 in each region may be controlled individually, wherein the bonding pads in each partition are connected in series, and the micro light emitting diodes 122 on the bonding pads are connected in parallel.

Fig. 8 is a schematic circuit diagram of a micro led in the prior art.

Referring to fig. 8, in the prior art, if the micro light emitting diodes 122 are partitioned, the micro light emitting diodes in each partition are connected in series, and the micro light emitting diodes between the partitions are connected in parallel. In fig. 8, a row of micro-leds 122 may represent a partition, and the micro-leds 122 in each row are connected in parallel, and the micro-leds 122 in each row are connected in series. Then when a micro led 122 fails or is poorly soldered, the sub-area where the failed micro led is located cannot be lit.

Referring to fig. 9, in the embodiment of the present invention, after the micro light emitting diodes 122 are partitioned, a row of pads are connected in series, and at least two micro light emitting diodes on each pad are connected in parallel, so that even if a micro light emitting diode fails, as long as a normal micro light emitting diode is still on one pad, the problem that the whole partition cannot be lit due to an open circuit is not generated.

According to the first invention concept, at least two micro light-emitting diodes are welded on at least one exposed bonding pad of the circuit board, and then the micro light-emitting diodes welded on the same bonding pad are in parallel connection; when the micro light-emitting diode fails on the bonding pad, as long as one micro light-emitting diode is normally welded and can normally emit light, the driving current can flow through the normal micro light-emitting diode, and meanwhile, the total light-emitting intensity is kept unchanged. From this, the maintenance probability of miniature emitting diode lamp plate can greatly reduced.

According to the second inventive concept, the circuit board includes: the circuit comprises a base material, a circuit layer and a solder mask layer. The circuit layer includes a pad for soldering the micro light emitting diode, and the solder resist layer includes an opening for exposing at least a portion of the pad. At least two openings are arranged above the bonding pad, and the openings are used for welding the micro light-emitting diodes. Openings of the solder mask layers corresponding to the bonding pads are mutually separated and not communicated, so that the problems of continuous welding and the like when the micro light-emitting diodes are welded on the bonding pads can be avoided, and the micro light-emitting diodes welded on the same bonding pad are ensured to be mutually connected in parallel.

According to the third inventive concept, two pads are exposed in each opening, and the two pads are arranged in pairs, respectively for soldering two electrodes of the micro light emitting diode. A gap with a certain distance exists between the two bonding pads, and the gap is not provided with a pattern of a circuit layer and used for blocking the two bonding pads, so that the problem of short circuit of the micro light-emitting diode is avoided.

According to the fourth invention concept, the solder mask is a protective layer positioned above the circuit board and has the function of diffuse reflection of incident light, so that light emitted by the panel of the micro light-emitting diode can be reflected to the light emitting side again by the solder mask when being reflected to one side of the back plate by elements in the backlight module, and the utilization efficiency of a light source is improved.

According to the fifth inventive concept, the expansion and contraction amount of the circuit board in the long side direction is larger, in order to ensure the welding yield of the micro light-emitting diode, the long side of the micro light-emitting diode is arranged to be parallel to the short side of the circuit board, and the short side direction of the micro light-emitting diode is arranged to be parallel to the long side direction of the circuit board.

According to the sixth inventive concept, when the micro light emitting diode is packaged by using the packaging adhesive, two forms of dispensing and whole layer gluing can be adopted. The glue dispensing and packaging mode can save packaging glue materials and reduce the cost; and the whole layer of gluing mode has higher packaging efficiency.

According to the seventh invention concept, the packaging layer of the miniature light-emitting diode lamp panel covers the surface of the miniature light-emitting diode at the side departing from the circuit board; the packaging layer is provided with mutually-separated patterns which correspond to the bonding pads one by one. The bonding pads are welded with at least two micro light-emitting diodes, and when the micro light-emitting diodes are packaged in a point packaging mode, the packaging layers can be formed on the surfaces of all the micro light-emitting diodes on one bonding pad, so that the micro light-emitting diodes on each bonding pad are packaged.

According to the eighth inventive concept, a reflection sheet is provided on a surface of the solder resist layer on a side close to the micro light emitting diode. The reflector plate has higher reflectivity compared with a solder mask on the surface of the circuit board, and can improve the reflection efficiency of light to the light-emitting side, thereby improving the light extraction efficiency of the backlight module and the utilization rate of a light source.

According to the ninth invention concept, the micro light emitting diode lamp panel is partitioned, the micro light emitting diodes in each area can be controlled independently, wherein the bonding pads in each partition are connected in series, and the micro light emitting diodes on the bonding pads are connected in parallel. Even if the micro light-emitting diode fails, the problem that the whole broken circuit partition cannot be lightened can not be caused as long as one normal micro light-emitting diode is arranged on one bonding pad.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A display device, comprising:

a display panel for image display;

the miniature light-emitting diode lamp panel is positioned at the light incident side of the display panel and used for providing backlight;

the miniature LED lamp plate includes:

a circuit board for providing a driving signal;

the micro light-emitting diode is positioned on the circuit board;

the circuit board comprises bonding pads for welding the micro light-emitting diodes, and at least two micro light-emitting diodes are welded on at least one bonding pad.

2. The display device of claim 1, wherein the circuit board comprises:

the substrate has supporting and bearing functions;

a circuit layer located on the substrate; the circuit layer comprises a bonding pad for welding the micro light-emitting diode;

the solder mask layer covers the surface of one side, away from the substrate, of the circuit layer and is used for insulating and protecting the circuit layer; the solder mask layer comprises openings for exposing at least part of the bonding pads, at least one bonding pad is provided with at least two mutually-discrete openings, and one micro light-emitting diode is welded on the bonding pad in each opening.

3. The display device according to claim 2, wherein two pads are exposed in the opening for soldering two electrodes of the micro light emitting diode, respectively; a gap exists between the two exposed pads.

4. The display device according to claim 2, wherein a material of the solder resist layer is white ink.

5. The display device according to claim 4, wherein a reflectance of the solder resist layer is greater than 95%.

6. The display device according to any one of claims 1 to 5, wherein the circuit board has a rectangular shape, and the micro light emitting diode has a rectangular shape;

the long side direction of the micro light-emitting diode is parallel to the short side direction of the circuit board, and the short side direction of the micro light-emitting diode is parallel to the long side direction of the circuit board.

7. The display device according to claim 6, wherein the opening of the solder resist layer is rectangular in shape;

the long side direction of the opening is parallel to the long side direction of the micro light-emitting diode, and the short side direction of the opening is parallel to the short side direction of the micro light-emitting diode;

the size of the opening is larger than that of the micro light-emitting diode.

8. The display device of claim 2, wherein the micro led light panel further comprises:

the packaging layer covers the surface of one side of the micro light-emitting diode, which is far away from the circuit board; the packaging layer is provided with mutually-discrete patterns which correspond to the bonding pads one by one.

9. The display device of claim 8, wherein the micro led light panel further comprises:

and the reflector plate is positioned on the surface of one side, close to the micro light-emitting diode, of the solder mask layer, and comprises an opening used for exposing the graph of the packaging layer.

10. The display device according to any one of claims 1 to 5, wherein the micro light emitting diode lamp panel is divided into a plurality of partitions, bonding pads in each partition are connected in series, and the micro light emitting diodes on the bonding pads are connected in parallel.