Small micro-pitch LED display screen

Abstract

The utility model relates to the technical field of LED screens, in particular to a small-micro-spacing LED display screen which comprises a plurality of LED lamp panels. The LED lamp panel comprises a PCB (printed circuit board) substrate; the top surface of the PCB substrate is provided with a plurality of LED wafers and a transparent adhesive layer; a film pasting layer is arranged on the transparent adhesive layer; the PCB substrate is also provided with a driving circuit which is used for driving the LED wafer. According to the scheme, the ink color consistency and the contrast ratio of the LED display screen can be improved, and the reflectance is reduced, so that the high-definition display of the LED display screen is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of LED screens, and particularly relates to a small-pitch LED display screen. Background Art

[0002] An LED display screen is a display device that uses light-emitting diodes (LEDs) as pixel points and is widely used in various indoor and outdoor display occasions; it has the characteristics of high brightness, wide viewing angle, long service life, and low energy consumption, and can present bright colors and clear images. The LED display screen can be customized with different sizes and resolutions according to different application scenarios, providing an excellent visual experience from large outdoor billboards to small indoor information display screens.

[0003] Although the existing LED display screens have been widely used in many fields, there are still some problems, such as the LED display screens are prone to problems of poor ink color consistency, low contrast, and high reflectivity, which will affect the high-definition display of the screen;

[0004] Therefore, there is an urgent need for a small-pitch LED display screen that can improve the poor ink color consistency and low contrast of the LED display screen, reduce the reflectivity, and ensure the high-definition display of the LED display screen. Summary of the Utility Model

[0005] The utility model aims to provide a small-pitch LED display screen that can improve the poor ink color consistency and low contrast of the LED display screen, reduce the reflectivity, and ensure the high-definition display of the LED display screen.

[0006] The utility model provides the following basic scheme: A small-pitch LED display screen, comprising: a plurality of LED lamp boards;

[0007] The LED lamp board includes: a PCB substrate;

[0008] A plurality of LED chips are arranged on the top surface of the PCB substrate, and a transparent glue layer is arranged;

[0009] A film layer is arranged on the transparent glue layer;

[0010] A driving circuit is further arranged on the PCB substrate for driving the LED chips.

[0011] Beneficial effects of the basic solution: In this solution, for the LED light board, a transparent adhesive layer is provided on its PCB substrate, and a PET optical film, that is, a film layer is provided, so that the consistency of the black screen ink color of the IED screen can be controlled through the consistency of the PCB and the optical film, reducing the reflectance to ensure the high-definition display of the LED display screen; and a driving circuit is also provided on the PCB substrate to drive the LED chips, ensuring the stable driving of the LEDs, thereby ensuring the high-definition display of the LED display screen.

[0012] In summary, this solution can improve the ink color consistency and low contrast that are prone to occur in LED display screens, reduce the reflectance, and ensure the high-definition display of LED display screens.

[0013] Furthermore, for the LED chips, flip-chip LED chips are adopted and fixedly installed on the PCB substrate by means of solder paste welding; the transparent adhesive layer encapsulates the LED chips with a molded epoxy glue, and the light transmittance is greater than 80%. The light transmittance is greater than 80%, and the surface is bright, playing a role in sealing and protection.

[0014] Furthermore, the light transmittance of the film layer is greater than 40%. The light transmittance of the film layer being greater than 40% further solves the ink color consistency problem, and the film layer can play the roles of anti-fingerprint, anti-reflection, scratch resistance, and improving the protection performance.

[0015] Furthermore, three LED chips of different colors are taken as a group, and the LED chips in a group are of the same polarity, where the same polarity includes: common cathode or common anode;

[0016] The LED chips include: red LED chips, green LED chips, and blue LED chips; one red LED chip, one green LED chip, and one blue LED chip are a group of LED chips, and the LED chips in a group are of the same polarity, including: common cathode or common anode. A common cathode / common anode compatible design is adopted, and different driving modes are realized by replacing the driving IC.

[0017] Furthermore, a driving circuit is also provided on the PCB substrate to drive the LED chips.

[0018] Furthermore, the side of the LED light board is sprayed with black ink. Spraying black ink on the side of the LED light board thus solves the problem of the white line at the splicing of the LED light boards.

[0019] Furthermore, it also includes: a cabinet;

[0020] One side of the cabinet is open, and several LED light boards are magnetically attracted to the frame on the open side. Several LED light boards are magnetically attracted to the frame on the open side to form an LED display screen, and the magnetic attraction method is convenient for installation and disassembly.

[0021] Furthermore, mounting holes are provided on the box body, and the spliced box bodies are fixed by bolts passing through the mounting holes. According to requirements, several box bodies are spliced together to form an LED display screen with a size that meets the requirements, better meeting the needs of users. Description of the Drawings

[0022] Figure 1 Schematic diagram of the structure of the LED lamp board in an embodiment of a small-pitch LED display screen of the present utility model;

[0023] Figure 2 Schematic diagram of the array arrangement of the LED driving row transistor MOS in an embodiment of a small-pitch LED display screen of the present utility model;

[0024] Figure 3 Circuit diagram of the first three rows of the first column of LED lamp boards in an embodiment of a small-pitch LED display screen of the present utility model;

[0025] Figure 4 Circuit diagram of the first three rows of the second column of LED lamp boards in an embodiment of a small-pitch LED display screen of the present utility model;

[0026] Figure 5 Circuit diagram of the first group of row driving chips in an embodiment of a small-pitch LED display screen of the present utility model;

[0027] Figure 6 Circuit diagram of the second group of row driving chips in an embodiment of a small-pitch LED display screen of the present utility model;

[0028] Figure 7 Schematic diagram of the array arrangement of the PWM driving chips of the LED display in an embodiment of a small-pitch LED display screen of the present utility model;

[0029] Figure 8 Circuit diagram of the PWM driving chips of the LED display in the first two rows and the first three columns in an embodiment of a small-pitch LED display screen of the present utility model;

[0030] Figure 9 Circuit diagram of the FLASH circuit in an embodiment of a small-pitch LED display screen of the present utility model;

[0031] Figure 10 Circuit diagram of the pin connector in an embodiment of a small-pitch LED display screen of the present utility model;

[0032] Figure 11 Circuit diagram of the second driver in an embodiment of a small-pitch LED display screen of the present utility model;

[0033] Figure 12This is the circuit diagram of the series inductor and capacitor of the second driver in an embodiment of a small-pitch LED display of the present utility model;

[0034] Figure 13 This is the circuit diagram of the EMC filter circuit in an embodiment of a small-pitch LED display of the present utility model;

[0035] Figure 14 This is the schematic structural diagram of the installation of the LED lamp board on the box body in an embodiment of a small-pitch LED display of the present utility model;

[0036] Figure 15 This is the schematic structural diagram of the box body in an embodiment of a small-pitch LED display of the present utility model. Specific embodiments

[0037] The following is a further detailed description through specific embodiments:

[0038] The reference numerals in the accompanying drawings of the specification include: PCB substrate 1, LED chip 2, transparent adhesive layer 3, film layer 4, drive circuit 5, box body 6, LED lamp board 7, drive board 8, mounting hole 9.

[0039] In the description of the present application, unless otherwise clearly defined and limited, the terms "first" and "second" are only used for the purpose of description and cannot be understood as indicating or implying relative importance; unless otherwise specified or stated, the term "plurality" means two or more; the terms "connection", "fixation", etc. should all be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0040] In the description of this specification, it should be understood that the orientation terms such as "upper", "lower", "left", "right", etc. described in the embodiments of the present application are described from the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that an element is connected "above", "below", "left" or "right" of another element, it can not only be directly connected "above", "below", "left" or "right" of another element, but also be indirectly connected "above", "below", "left" or "right" of another element through an intermediate element.

[0041] The embodiment is basically as shown in the attached Figure 1 shown: A small-pitch LED display includes: a plurality of LED lamp boards 7 and a box body 6;

[0042] The LED lamp board 7 includes: a PCB substrate 1;

[0043] On the top surface of the PCB substrate 1, a number of LED chips 2 are provided, and a transparent adhesive layer 3 is provided to seal and protect the LED chips 2. Among them, the LED chips 2 are flip-chip LED chips 2, which are fixedly installed on the PCB substrate 1 by means of solder paste welding. In this embodiment, LEDs with a size of 3x6 mil are used. The transparent adhesive layer 3 encapsulates the LED chips 2 with a molded epoxy glue, having a light transmittance greater than 80%, a thickness of 200 microns, and a bright surface, playing a role in sealing and protection.

[0044] Among them, three LED chips 2 of different colors are grouped together, and the LED chips 2 in a group share the same electrode, including: common cathode or common anode.

[0045] The LED chips 2 include: red LED chips 2, green LED chips 2, and blue LED chips 2. One red LED chip 2, one green LED chip 2, and one blue LED chip 2 form a group of LED chips 2, and the LED chips 2 in a group share the same electrode, including: common cathode or common anode.

[0046] A film layer 4 is provided on the transparent adhesive layer 3. The film layer 4 has a light transmittance of about 40% and a thickness of 90 microns. It uses a film with anti-fingerprint, anti-reflection, and scratch-resistant properties, and the film layer 4 can solve the problem of ink color consistency.

[0047] A driving circuit 5 is also provided on the PCB substrate 1 for driving the LED chips 2.

[0048] The driving circuit 5 includes: a driving IC and an LED driving circuit.

[0049] The LED driving circuit is provided on the side of the PCB substrate 1 where the LED chips 2 are installed, and the driving IC is provided on the other side of the PCB substrate 1. The driving IC and the LED driving circuit are both provided with solder pads on the PCB substrate 1 and are connected to the PCB substrate 1 by means of solder paste welding, so as to be connected through the PCB substrate 1.

[0050] The LED driving circuit includes: a number of LED driving line transistors MOS.

[0051] Light-emitting diodes are provided on the LED driving line transistors MOS, and the LED chips 2 are located in the light-emitting diodes. The LED chips 2 include: red light-emitting diodes, green light-emitting diodes, and blue light-emitting diodes. One red light-emitting diode, one green light-emitting diode, and one blue light-emitting diode are combined into one pixel, and the light-emitting diodes of one pixel are set with common cathode or common anode.

[0052] The light-emitting diodes of one pixel are arranged side by side in a cycle on the LED driving row transistor MOS. The light-emitting diodes of one pixel are a red light-emitting diode, a green light-emitting diode, and a blue light-emitting diode, arranged side by side in a cycle, and the positive and negative electrodes respectively correspond to different interfaces of the LED driving row transistor MOS. Specifically, as Figure 3 shown, 15 groups of light-emitting diodes of the three primary colors are arranged on one LED driving row transistor MOS;

[0053] In this embodiment, the array is provided with 18 LED driving row transistor MOSs. Two LED driving row transistor MOSs are arranged in one row, and 9 LED driving row transistor MOSs are arranged in one column. As Figure 2 shown, the specific numbering sequence is as Figure 3 and Figure 4 shown. Figure 3 is the LED driving row transistor MOS of the first three rows in the first column, Figure 4 is the LED driving row transistor MOS of the first three rows in the second column;

[0054] The driving IC includes: a row driving circuit 5, a constant current driving circuit 5, a FLASH circuit, an interface control circuit, and an EMC filtering circuit;

[0055] The row driving circuit 5 includes: a plurality of row driving chips;

[0056] A plurality of row driving chips are grouped and connected in series to form the row driving circuit 5. The upper interfaces of the LED driving row transistor MOSs in the same column are connected to the output interfaces of the row driving chips in the same group of the row driving circuit 5;

[0057] Specifically, in this embodiment, eight row driving chips are provided, four in a group, connected in series. The DOUT interface of one row driving chip is connected to the DIN(C) interface of the next row driving chip. For the two groups of serially connected row driving chips, the output interface of the first group is connected to the upper interface of the LED driving row transistor MOS in the first column; the output interface of the second group is connected to the upper interface of the LED driving row transistor MOS in the second column; specifically, see the interface numbers in the appendix Figure 5 and 6 . If the interface numbers are the same, it means the two interfaces are connected; among them Figure 5 and Figure 6 are the first group and the second group respectively;

[0058] The constant current driving circuit 5 includes: a plurality of LED display PWM driving chips; in this embodiment, a PWM constant current output LED common cathode driving chip is used, such as CND2069 SSOP24-0.635;

[0059] A number of LED display PWM driver chips are grouped in series to form a constant current drive circuit 5. The interfaces corresponding to the light-emitting diodes of the same color at the lower part of the LED drive line MOS in the same column are connected to the output interfaces of the LED display PWM driver chips in the same group of the constant current drive circuit 5;

[0060] Specifically, as Figure 7 and Figure 8 shown, in this embodiment, fifty-four LED display PWM driver chips are set, nine in a group, and connected in series. The SDO interface of one LED display PWM driver chip is connected to the SDI interface of the next LED display PWM driver chip; six groups of serially connected LED display PWM driver chips; the output interface of the first group is connected to the interface corresponding to the green light-emitting diode at the lower part of the LED drive line MOS in the first column; the output interface of the second group is connected to the interface corresponding to the red light-emitting diode at the lower part of the LED drive line MOS in the first column; the output interface of the third group is connected to the interface corresponding to the blue light-emitting diode at the lower part of the LED drive line MOS in the first column; the output interface of the fourth group is connected to the interface corresponding to the green light-emitting diode at the lower part of the LED drive line MOS in the first column; the output interface of the fifth group is connected to the interface corresponding to the red light-emitting diode at the lower part of the LED drive line MOS in the first column; the output interface of the sixth group is connected to the interface corresponding to the blue light-emitting diode at the lower part of the LED drive line MOS in the first column; where Figure 8 are the LED display PWM driver chips in the first two rows of the first three columns, and the numbering rule is as Figure 8 shown;

[0061] The FLASH circuit includes: a first driver, a low-dropout regulator, and a FLASH flash memory; in this embodiment, the first driver uses a 74HC245 chip, the low-dropout regulator uses a 1117-3.3, and the FLASH flash memory uses a W25Q32;

[0062] The first driver, the low-dropout regulator, and the FLASH flash memory are interconnected to form a FLASH circuit;

[0063] Specifically, the VIN interface of the low-dropout regulator is connected to the VCC interface of the first driver;

[0064] The OUT1 interface of the low-dropout regulator is connected to the VCC0 interface, VCC1 interface, and VCC2 interface of the FLASH flash memory;

[0065] The B4 interface of the first driver is connected to the DATA interface of the FLASH flash memory;

[0066] The A5 interface, A6 interface, and A7 interface of the first driver are respectively connected to the nCS interface, DCLK interface, and ASDI interface of the FLASH flash memory through resistor R103, resistor R102, and resistor R100, and the interfaces are all grounded, as Figure 9 shown; The interface control circuit includes: a pin connector and several second drivers;

[0067] Several second drivers are all connected to the pin connector, and the first driver is also connected to the pin connector, as Figure 10 shown;

[0068] In this embodiment, the pin connector uses HEADER_32x2, and the second driver uses a 74HC245 chip, as Figure 11 shown;

[0069] The A4 interface, B5 interface, B6 interface, and B7 interface of the first driver are respectively connected to the 39th interface, 40th interface, 46th interface, and 45th interface of the pin connector;

[0070] There are four second drivers, all connected to the pin connector, and each second driver is connected to a grounding circuit; The DCLK1 interface, DCLK2 interface, DCLK3 interface, DCLK4 interface, DCLK5 interface, and DCLK6 interface of the second driver are all connected in series with an inductor and a capacitor, and the other end is grounded; The DOE1 interface, DOE2 interface, DOE3 interface, DOE4 interface, DOE5 interface, and DOE6 interface of the second driver are all connected in series with an inductor and a capacitor, and the other end is grounded; The DLAT1 interface, DLAT2 interface, DLAT3 interface, DLAT4 interface, DLAT5 interface, and DLAT6 interface of the second driver are all connected in series with an inductor and a capacitor, and the other end is grounded, as Figure 12 shown.

[0071] The EMC filter circuit includes: several parallel capacitors, connected to the VR interface and GND interface of the pin connector for filtering, as Figure 13 shown.

[0072] When designing the LED light board 7, first determine the target brightness N of the LED display screen. 1.3 times of N is the designed brightness N1 of the LED light board 7, where the extra 30% is reserved for correcting brightness attenuation; Determine the design of the scanning number according to N1; The larger the scanning number, the fewer times the LED is cyclically lit per second, and the lower the brightness. Taking P1.25 as an example, if the brightness of N1 is 600 nit, the scanning number needs to reach within 64 scans.

[0073] According to the pixel resolution of the LED light board 7, determine the number of driving and scanning areas. For example, the resolution of a single P1.25 light board is 120x135. There are two optional scanning schemes: 60 scans, 2 scanning areas and 45 scans, 3 scanning areas. For a single channel of the row driving IC, the number of pixels driven is preferably controlled at around 130 points.

[0074] When laying out the driving IC, it should be noted that the power signal interface should be placed as close as possible to the center of the LED light board 7 to ensure that the line lengths to each area are equal, the attenuated voltages are equal, and to avoid brightness differences caused by inconsistent voltage attenuation. The position of each IC should be placed at the center of the area of the LED chips 2 it controls, ensuring that the wiring lengths from the IC to each LED chip 2 are equal, reducing signal delay and voltage attenuation, and ensuring brightness consistency.

[0075] The design of the EMC filtering circuit needs to comply with the 3W20H principle. It is advisable to use an RC filtering circuit near the interface circuit to filter high-speed DATA, CLK, LAT, and OE signals to reduce radiation.

[0076] The FLASH circuit is connected to the signal connector of the external system. The interface control circuit and the EMC filtering circuit are connected in series between the signal connector and the row driving circuit 5 / constant current driving circuit 5. The connection interface is directly conducted through copper wires and is not a standard universal interface.

[0077] The side of the LED light board 7 is sprayed with black ink to ensure the black consistency after the LED light boards 7 are spliced.

[0078] Such as Figure 14 and 15 As shown, one side of the box body 6 is open, and several LED light boards 7 are magnetically attracted to the frame on the open side. Specifically, magnets are provided on the bottom surface of the LED light board 7, and it is magnetically attracted to the frame on the open side through the magnets. In this embodiment, eight LED light boards 7 are installed on one box body 6.

[0079] A driving board 8 is provided inside the box body 6. The LED light board 7 is connected to the driving board 8 for driving the LED light board 7.

[0080] The driving board 8 is connected to an external power supply through a wire, connected to an external video image input through a network cable, and transmitted to the LED light board 7 for display.

[0081] Mounting holes 9 are provided on the box body 6, and the splicing box bodies 6 are fixed by bolts passing through the mounting holes 9, thereby splicing multiple box bodies 6 together.

[0082] The above are only the embodiments of the present utility model. Specific structures and common knowledge such as characteristics that are well-known in the art are not described in detail herein. Those of ordinary skill in the art know all the general technical knowledge in the technical field to which the utility model belongs before the filing date or the priority date, are able to obtain all the prior art in this field, and have the ability to apply conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to complete and implement this solution. Some typical well-known structures or well-known methods should not become obstacles for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present utility model, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present utility model, and these will not affect the implementation effect of the present utility model and the practicality of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A small-pitch LED display screen, characterized in that Including: A number of LED lamp boards; The LED lamp board includes: a PCB substrate; On the top surface of the PCB substrate, a number of LED chips are provided, and a transparent adhesive layer is provided; A film layer is provided on the transparent adhesive layer; A drive circuit is also provided on the PCB substrate for driving the LED chips.

2. The small-pitch LED display screen according to claim 1, wherein The LED chips are flip-chip LED chips and are fixedly installed on the PCB substrate by means of solder paste welding; the transparent adhesive layer encapsulating the LED chips uses a molded epoxy glue with a light transmittance greater than 80%.

3. The small-pitch LED display screen according to claim 1, wherein The light transmittance of the film layer is greater than 40%.

4. The small-pitch LED display screen according to claim 1, wherein Three LED chips of different colors are grouped together, and the LED chips in a group are of the same polarity, where the same polarity includes: common cathode or common anode; The LED chips include: red LED chips, green LED chips, blue LED chips; one red LED chip, one green LED chip, and one blue LED chip form a group of LED chips, and the LED chips in a group are of the same polarity, including: common cathode or common anode.

5. The small-pitch LED display screen according to claim 1, wherein A drive circuit is also provided on the PCB substrate for driving the LED chips.

6. The small-pitch LED display screen according to claim 1, characterized in that, The side of the LED lamp board is sprayed with black ink.

7. The small-pitch LED display screen according to claim 1, characterized in that, Also including: A box body; One side of the box body is open, and a number of LED lamp boards are magnetically attracted to the frame on the open side.

8. The small-pitch LED display screen according to claim 7, wherein, Mounting holes are provided on the box body, and the spliced box bodies are fixed by bolts passing through the mounting holes.

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