A bidirectional transmission series-parallel combined LED driving circuit system

Abstract

The application provides a bidirectional transmission series-parallel combined LED driving circuit system, the LED driving circuit and control mechanism are improved, the LED driving circuit adopts a parallel and series combined mode, avoids the defect that single circuit damage or single wire breakage in the series circuit leads to all LED driving circuits in the later stage being invalid; the LED driving circuit has signal transmission direction monitoring and signal transmission port input / output mode control functions, bidirectional input of signals is realized; when a signal transmission port in the driving circuit is invalid, has no signal input or has signal error, a data frame can still be input to the LED driving circuit through another signal transmission port, the reliability of the system is greatly improved, and the problem of LED driving circuit invalidation caused by signal disconnection or error in the traditional unidirectional signal transmission system is solved.

Description

Technical Field

[0001] This application relates to the field of LED display technology, specifically to a bidirectional transmission series-parallel combined LED driving circuit system. Background Technology

[0002] In LED driver circuits, data frames are typically forwarded sequentially through LED driver units. Existing cascaded series connections have the following drawbacks: signals are forwarded one LED at a time; failure or damage to a single LED driver circuit or a broken signal line can cause all subsequent LED driver units to fail and lose signal reception. While existing series-parallel connections can address signal interruptions caused by the failure of a single LED driver unit, they cannot resolve signal interruptions in subsequent stages due to broken series signal transmission lines. Therefore, a more reliable signal control solution is needed. Summary of the Invention

[0003] Given that existing LED driver circuits use a pure series cascade method, with control signals forwarded stage by stage, the failure of a single LED driver circuit or a break in the signal transmission line can cause all subsequent LED driver circuits to fail, resulting in their inability to receive control signals. While existing series-parallel solutions can address signal interruption caused by the failure of a single LED driver circuit, they cannot solve the problem of signal interruption in subsequent stages due to a break in the series signal transmission line. Furthermore, traditional solutions only support unidirectional signal transmission, meaning signals can only be input from one fixed end. If the link in that input direction fails, the entire system will cease to function. Therefore, this application provides a bidirectional transmission series-parallel combined LED driver circuit system.

[0004] This application provides a bidirectional transmission series-parallel combined LED driving circuit system, including a controller and L LED driving circuit groups, wherein the L LED driving circuit groups are connected in series, each LED driving circuit group includes K LED driving circuits connected in parallel, and each LED driving circuit has a first signal transmission port and a second signal transmission port with data transmission function; K and L are both natural numbers greater than or equal to 1.

[0005] Each LED driver circuit in the LED driver circuit group has a corresponding feature code. Each data frame output by the controller includes a frame header and L data groups. Each data group includes K data packets corresponding to the LED driver circuit group. The frame header is used to verify each data frame. The LED driver circuit in the LED driver circuit group verifies and reads the matching data packets according to the corresponding feature code.

[0006] Both the first signal transmission port and the second signal transmission port can dynamically switch the transmission mode to input mode or output mode. The controller outputs data frames to the first LED driving circuit group or the Lth LED driving circuit group. The LED driving circuit can monitor the transmission status of the data frame and switch the input mode or output mode of the first signal transmission port and the second signal transmission port. When the LED driving circuit detects an abnormality in the current input signal transmission, it controls the first signal transmission port or the second signal transmission port to switch to another mode so that the data frame is transmitted in another direction.

[0007] As an improvement of this application, when the first signal transmission port or the second signal transmission port is in input mode, if the LED driving circuit does not detect data within a preset waiting time, detects that the level has not changed within a preset waiting time, or receives T consecutive data frames with incorrect format, the input and output modes of the two signal transmission ports are switched, that is, the signal transmission port in input mode is switched to output mode, and the signal transmission port in output mode is switched to input mode, where T is a natural number ≥1.

[0008] As an improvement of this application, at any given time, only one of the first signal transmission ports and the second signal transmission port of each LED driver circuit is in input mode, while the other port is in output mode.

[0009] As an improvement of this application, the LED driving circuit includes a data receiving and forwarding circuit. After receiving the correct data frame, each LED driving circuit in any LED driving circuit group reads the corresponding data packet from the current data frame according to the feature code of its own LED driving circuit, deletes the data group already read in the received data frame, and forwards it to the next level LED driving circuit group.

[0010] As an improvement of this application, when the number of data groups in the data frame is greater than L, each LED driving circuit group reads the first data group and forwards the remaining data groups transparently; when the number of data packets in any data group is greater than K, each LED driving circuit in the LED driving circuit group only reads the target data packet corresponding to its own feature code and forwards the remaining data packets transparently.

[0011] As an improvement of this application, the LED driving circuit includes a data receiving and forwarding circuit, which includes an input signal line connecting the first signal transmission port and the second signal transmission port, a data register, a frame header register, a PWM signal generator, a signal detector, a counter, a control signal generator, and a selector.

[0012] The input terminal of the counter is connected to the input signal line, and the output terminal is connected to the control signal generator, which is used to count the input signal and output a counting signal.

[0013] The output terminal of the control signal generator is connected to the PWM signal generator, the frame header register and the selector respectively, and outputs a first control signal, a second control signal and a third control signal according to the counting signal;

[0014] The input terminal of the data register is connected to the input signal line, and the output terminal is connected to the PWM signal generator and the frame header register respectively.

[0015] The PWM signal generator receives the first control signal and generates a PWM drive signal based on the data output from the data register.

[0016] The frame header register receives a second control signal, its input is connected to the data register, and its output is connected to the first input of the selector and the signal detector.

[0017] The signal detector is also connected to the input signal line to detect whether there is a signal input and to output a reset signal to the counter;

[0018] The second input terminal of the selector is connected to the input signal line, the control terminal receives the third control signal, and the output terminal is used to output the data packet to be forwarded.

[0019] As an improvement of this application, the data frame is input simultaneously from the first-stage LED driver circuit group and the last-stage LED driver circuit group, or input from one end and the other end serves as a redundant backup.

[0020] As an improvement of this application, the LED driving circuit continuously detects the data frame and the transmission mode switching of the signal transmission port until a correct data frame is detected by any signal transmission port, then locks the current mode of the signal transmission port and stops switching, and performs control data reception and forwarding.

[0021] As an improvement of this application, the data packet carries display data corresponding to the LED driving circuit, and the display data includes red grayscale data, green grayscale data and blue grayscale data.

[0022] As an improvement of this application, each LED driving circuit in each LED driving circuit group is configured with a feature code, which is used to determine the data packet to be read by the corresponding LED driving circuit in the first data group of the data frame; each feature code corresponds to a different data packet in the first data group of the received data frame, so that each LED driving circuit reads the corresponding target data packet according to its own feature code; the feature codes of each LED driving circuit in the same LED driving circuit group are different from each other, and the feature codes of different LED driving circuit groups can be the same.

[0023] The beneficial effects of this application are as follows: Compared with the prior art, this application provides a bidirectional transmission series-parallel combined LED driver circuit system, which adopts a structure of L LED driver circuit groups connected in series, with each group containing K parallel LED driver circuits. It retains the advantages of simple wiring and small port occupation of the series cascade structure. At the same time, the parallel design ensures that when a single LED driver circuit in a single group is damaged or detached, it will not affect the signal forwarding function of other driver circuits in the same group, avoiding the problem of a single point failure causing the entire signal link to fail in the pure series structure. In addition, this application supports bidirectional dynamic signal transmission. Each LED driver circuit can autonomously detect the signal status of the current input port. When an abnormal signal transmission is detected, it can automatically switch the transmission mode of the two ports, allowing the data frame to be input from the other direction. After the signal link is broken or the port is short-circuited, it can automatically adjust the transmission path to bypass the fault area, ensuring that all non-faulty LED driver circuits can receive control data normally. This solves the problem that the input link failure in the traditional unidirectional transmission scheme directly leads to the paralysis of the entire system, greatly improving the fault tolerance and operational reliability of the LED display drive system, and adapting to the long-term stable operation requirements of large-size LED splicing screens.

[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0026] Figure 1 This is a schematic diagram of the overall topology of the LED driver circuit system of this application;

[0027] Figure 2 This is a schematic diagram of the data frame format structure transmitted from the DATA1 direction in this application;

[0028] Figure 3 This is a schematic diagram of the data frame format structure sent from the DATA2 direction in this application;

[0029] Figure 4 This is a fault diagram of the LED driver circuit system of this application under the fault of signal transmission link disconnection or port short circuit.

[0030] Figure 5 This is a block diagram of the data receiving and forwarding circuit inside the LED driver circuit of this application;

[0031] Figure 6 This is a timing diagram of the data deletion and forwarding process of the LED driver circuit in this application. Detailed Implementation

[0032] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0033] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0034] In this document, the term "comprising" indicates the presence of a described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," with exclusions being otherwise specifically emphasized. Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying one or more of the feature. In the description of embodiments of this application, unless otherwise stated, "a plurality of" means two or more.

[0035] In this text, the term "and / or" simply describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " in this text generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In LED driver circuits, data frames are typically forwarded sequentially through LED driver units. Existing cascaded series connections have the following drawbacks: signals are forwarded one LED at a time; failure or damage to a single LED driver circuit or a broken signal line can cause all subsequent LED driver units to fail and lose signal reception. While existing series-parallel connections can address signal interruptions caused by the failure of a single LED driver unit, they cannot resolve signal interruptions in subsequent stages due to broken series signal transmission lines. Therefore, a more reliable signal control solution is needed.

[0037] To address the issue that existing LED driver circuits, which use a pure series cascade configuration and relay control signals stage by stage, suffer from the inability of any subsequent LED driver circuit to receive control signals and thus fail when a single LED driver circuit fails or a signal transmission line breaks, existing series-parallel solutions, while capable of handling signal interruptions caused by a single LED driver circuit failure, cannot resolve signal interruptions in subsequent stages due to a break in the series signal transmission line. Furthermore, traditional solutions only support unidirectional signal transmission, meaning signals can only be input from one fixed end; if the link in that input direction fails, the entire system ceases to function.

[0038] This application provides a bidirectional transmission series-parallel combined LED driving circuit system, including a controller and L LED driving circuit groups connected in series. Each LED driving circuit group includes K LED driving circuits connected in parallel, and each LED driving circuit has a first signal transmission port and a second signal transmission port with data transmission function; K and L are both natural numbers greater than or equal to 1; the first signal transmission port and the second signal transmission port can dynamically switch the transmission mode to input mode or output mode. The controller outputs data frames to the first LED driving circuit group or the Lth LED driving circuit group. The LED driving circuit can monitor the transmission status of the data frame and switch the input mode or output mode of the first signal transmission port and the second signal transmission port. When the LED driving circuit detects an abnormality in the current input signal transmission, it controls the first signal transmission port or the second signal transmission port to switch to another mode so that the data frame is transmitted in another direction.

[0039] Specifically, such as Figure 1As shown, the LED driver circuit system includes a controller and L LED driver circuit groups, which are connected in series. Each LED driver circuit group includes K LED driver circuits connected in parallel, where K and L are natural numbers greater than or equal to 1. The signal transmission ports of the K LED driver circuits within the same LED driver circuit group are connected in parallel, and then the groups are cascaded sequentially. The controller is connected to the signal transmission port of the first LED driver circuit group (level 1) via data line DATA1, and to the signal transmission port of the last LED driver circuit group (level L) via data line DATA2. All LED driver circuits have their VDD pins connected in parallel for power supply, and all LED driver circuits have their GND pins connected in parallel for ground. Each LED driver circuit has a first signal transmission port (IO1) and a second signal transmission port (IO2), both of which can be dynamically switched between input and output modes. Through this parallel-then-series topology, when a certain LED driver... When a single LED driver circuit in the circuit group is damaged or detached, only the signal output path of that LED driver circuit itself will be cut off. The remaining parallel LED driver circuits in the group can still work normally, avoiding the defect of a single circuit failure causing the failure of all subsequent stages in a series circuit. It will not affect the normal data reception and transmission of other driver circuits. Compared with the traditional pure series LED driver topology, the bidirectional transmission design of the series-parallel combination in this application greatly reduces the impact of a single point of failure on the entire system. At the same time, the bidirectional transmission port configuration can support signal injection from either end, which makes it convenient for the driver circuit to flexibly adjust the wiring layout according to actual installation requirements. There is no need to change the PCB wiring design to match a fixed signal flow direction, which can be adapted to more special installation scenarios such as irregular screens and splicing screens.

[0040] Regarding the format of the data frame, such as Figure 2 As shown in Figure 3, for example, Figure 1 For an LED driver circuit to ensure that all LEDs can receive data, the structure of each data frame in DATA1 or DATA2 is as follows: it contains a customizable and editable frame header (e.g., FH) to determine whether the data format is correct, L DAs; each DA contains K DPs, so a data frame contains L×K DPs.

[0041] In this embodiment, each LED driver circuit in each LED driver circuit group has a corresponding feature code (ID). The feature code is used to identify and read the data packets that match the group in the data frame. Each data frame output by the controller includes a frame header (FH) and L data groups (DA1~DAL). Each data group includes K data packets (DP1~DPK) corresponding to the LED driver circuit group. That is, each data frame contains a total of L×K data packets. The frame header is used to verify each data frame. The frame header is located at the beginning of the data frame and is used to verify the format of each data frame. A pre-set value is set before the frame header. With a fixed reset time, each LED driver circuit in the LED driver circuit group verifies and reads the matching data packet according to the corresponding feature code. After receiving the data frame, each LED driver circuit in the LED driver circuit group verifies and reads the matching data packet from the current data frame according to its own feature code. For example, the LED driver circuit with feature code i reads the data in the i-th data packet of the current data group. Each data packet carries the display data of the corresponding LED driver circuit. The display data includes red grayscale data, green grayscale data and blue grayscale data. For example, each data packet is 48 bits.

[0042] In this embodiment, the LED driver circuit continuously monitors whether there is a valid data frame input at the signal transmission port in input mode. When the first signal transmission port or the second signal transmission port is in input mode, if the LED driver circuit does not detect data within a preset waiting time, detects no change in level within the preset waiting time (e.g., continuously high level or continuously low level), or receives T data frames (where T is a natural number > 1) with incorrect format, the LED driver circuit determines that the current input signal transmission is abnormal and performs a direction switching operation on the signal transmission port, switching the input and output modes of the two signal transmission ports. Specifically, the signal transmission port that was originally in input mode is switched to output mode, and the signal transmission port that was originally in output mode is switched to input mode. That is, the signal transmission port that was originally in input mode is switched to output mode, and the signal transmission port that was originally in output mode is switched to input mode. After the switching is completed, the LED driver circuit continues to detect whether there is a valid signal input at the new port in input mode. The specific waiting time of the LED driver circuit can be flexibly configured according to the application scenario, such as 1 millisecond, 5 milliseconds, or 10 milliseconds.

[0043] Regarding the situation where the LED driver circuit does not detect data within a preset waiting time, a timer is set inside the LED driver circuit. When a certain signal transmission port is configured as an input mode, the timer starts counting. The duration of this timer is the "preset waiting time". This time threshold can be flexibly configured according to the application scenario. For example, it can be configured to 1 millisecond, 5 milliseconds, 10 milliseconds or longer. The specific value is determined by the system clock frequency and communication rate, and this implementation method does not limit it.

[0044] Within a preset waiting time period, the LED driver circuit continuously monitors the level changes on the first signal transmission port and the second signal transmission port. If no data signal is detected at the signal transmission port during this time period, i.e. the port level remains invalid, the signal transmission port outputs "no signal". After detecting this flag, the LED driver circuit determines that the current input signal transmission is abnormal and immediately performs a direction switching operation.

[0045] Similar to the above process, when the signal transmission port detects the presence of a level within a preset waiting time but it remains unchanged, such as continuously high level, continuously low level, or no high-low level transition, the LED driving circuit also determines it as an invalid signal input. In this embodiment, the specific criterion for determining that the level has not changed is: within the preset waiting time, the input signal does not generate any rising or falling edge transition. The direction switching triggered by this condition complements the "no data" detection and can effectively cope with fault scenarios such as continuous high level due to short circuit to power supply or continuous low level due to short circuit to ground.

[0046] When a signal transmission port in input mode receives a data frame, the LED driver circuit first performs a format check on the data frame through the frame header. If T consecutive data frames with incorrect format are received (T is a natural number greater than 1, such as T=3, T=5, or T=10), the LED driver circuit determines that the current input signal transmission is abnormal and performs a direction switching operation on the signal transmission port. Specifically, the signal transmission port that was originally in input mode is switched to output mode, and the signal transmission port that was originally in output mode is switched to input mode. After the switching is completed, the LED driver circuit continues to detect whether the new port in input mode has a data frame with the correct format. By introducing a judgment method of counting consecutive error frames, frequent false switching caused by occasional errors in a single frame is avoided, thus improving the stability and anti-interference capability of the system.

[0047] In this embodiment, at any given time, only one of the first and second signal transmission ports of each LED driver circuit is in input mode, while the other port is in output mode. Since only one of the two signal transmission ports (IO1 and IO2) of each LED driver circuit is in input mode and the other port is in output mode at any given time, the LED driver circuit can be configured with one of the following two methods after power-on: Method 1: Pre-configure port IO1 as input mode and port IO2 as output mode (or vice versa); Method 2: After power-on, the LED driver circuit continuously detects ports IO1 and IO2, sets the port that first detects a valid signal as input mode, and automatically sets the other port as output mode. Through the above configuration, it is ensured that each LED driver circuit has unidirectional signal transmission capability in the initial state.

[0048] In this embodiment, the data packet carries the display data corresponding to the LED driving circuit. The display data includes red grayscale data, green grayscale data, and blue grayscale data. Each data packet corresponds to the brightness control information of a frame of display. After receiving the matching data, all LED driving circuits will synchronously update the PWM duty cycle output to the LED beads according to the frame timing, thereby achieving precise control of the color and brightness of the entire screen display. Furthermore, this application simplifies the data transmission verification process through the layered encapsulation structure design of the data packet, and significantly reduces the probability of data packet loss and error during transmission, further improving the display stability of the LED display screen.

[0049] In this embodiment, the LED driving circuit includes a data receiving and forwarding circuit. After receiving a correct data frame, any LED driving circuit group's data receiving and forwarding circuit reads the corresponding data packet from the current data frame according to its own LED driving circuit's signature, deletes the already read data group in the received data frame, and forwards it to the next-level LED driving circuit group. Taking the controller sending a data frame via DATA1 as an example, the data receiving and forwarding process is explained in detail. When the first-level LED driving circuit group receives a data frame, the data receiving and forwarding circuits of the K LED driving circuits in the group read the corresponding K data packets from the first data group (DA1) of the data frame according to their own signatures. After reading, the first-level LED driving circuit group deletes the first read data group in the received data frame, and then forwards the remaining data frame (including the frame header and DA2~DAL) to the next-level LED driving circuit group. After the second-level LED driving circuit group receives the remaining data frame, its data receiving and forwarding circuit reads the corresponding data packet from the new first data group (DA2) according to the signature of each LED driving circuit in the current group, deletes the already read data group again, and continues forwarding. This process continues until all L-level LED driver circuit groups have read their respective data packets. Through the above-mentioned "read, delete, and forward" method, the length of the data frame is reduced by K data packets for each level of LED driver circuit group, effectively reducing the redundancy of data transmission.

[0050] In this embodiment, when the number of data groups in a data frame is greater than L, each LED driver circuit group reads the first data group and forwards the remaining data groups transparently. When the number of data packets in any data group is greater than K, each LED driver circuit in that group only reads the target data packet corresponding to its own feature code and forwards the remaining data packets transparently. The number of data groups in the data frame output by the controller can be equal to or greater than the number of LED driver circuit groups L. When the number of data groups in a data frame is greater than L, each level of LED driver circuit group still processes data by reading the first data group in the current data frame level by level. Specifically, after receiving a data frame, the first-level LED driver circuit group takes the first data group after the frame header as the current data group to be read. Each LED driver circuit in the first-level LED driver circuit group reads the target data packet that matches its own configured feature code from this data group. After completing the reading of the current data group, the data that has been processed in the current level will no longer participate in the target data reading of subsequent levels. The remaining unprocessed data groups continue to be forwarded to the next-level LED driver circuit group through the data receiving and forwarding circuit. After receiving the forwarded data frame, the second-level LED driver circuit group takes the first data group after the frame header as the current data group to be read, and completes the data reading and subsequent data forwarding in the same way. This process is repeated so that each LED driver circuit group can obtain its corresponding data in sequence using the same data processing rules.

[0051] The number of data packets in any data group can be equal to or greater than the number K of LED driver circuits in the corresponding LED driver circuit group. When the number of data packets in the current data group is equal to K, each of the K LED driver circuits in the LED driver circuit group reads the corresponding target data packet according to its own feature code, so that the K data packets in the current data group are used by the corresponding LED driver circuits. When the number of data packets in the current data group is greater than K, each LED driver circuit in the LED driver circuit group still only reads the target data packet corresponding to its own feature code. For the remaining data packets that do not correspond to any LED driver circuit feature code in the current LED driver circuit group, no reading operation is performed, and their data content is neither modified nor deleted. Instead, their original content and arrangement are maintained, and they continue to be passed forward through the data receiving and forwarding circuit. The current LED driver circuit group thus only processes the data packets it needs and will not affect data packets that exceed the processing capacity of the current LED driver circuit group.

[0052] Furthermore, when the number of data groups in a data frame is greater than L, and the number of data packets in at least one data group is simultaneously greater than K, the two transparent transmission processing methods described above can coexist. Each LED driver circuit group at each level processes only the first data group corresponding to the current level, and each LED driver circuit within the group only reads the target data packet corresponding to its own feature code; for data packets in the current data group that have not been read, and for data groups after the current level that have not yet entered the processing range, the data receiving and forwarding circuits retain their data content and continue to forward them according to the original transmission order. Through the above method, each LED driver circuit group can process only the data it actually needs, reducing the data processing coupling between levels, while improving the adaptability of the data frame format to different numbers of LED driver circuit groups and different numbers of data packets.

[0053] In this embodiment, please refer to Figure 5 The LED driver circuit includes a data receiving and forwarding circuit, which includes an input signal line connecting the first signal transmission port and the second signal transmission port, a data register, a frame header register, a PWM signal generator, a signal detector, a counter, a control signal generator, and a selector.

[0054] The input terminal of the counter is connected to the input signal line, and the output terminal is connected to the controller. It is used to count the input signal and output the count signal.

[0055] The output of the control signal generator is connected to the PWM signal generator, the frame header register, and the selector, respectively, and outputs the first control signal, the second control signal, and the third control signal according to the counting signal.

[0056] The input terminal of the data register is connected to the input signal line, and the output terminal is connected to the PWM signal generator and the frame header register respectively;

[0057] The PWM signal generator receives the first control signal and generates a PWM drive signal based on the data output from the data register;

[0058] The frame header register receives the second control signal, its input is connected to the data register, and its output is connected to the first input of the selector and the signal detector.

[0059] The signal detector is also connected to the input signal line to detect whether there is a signal input and to output a reset signal to the counter;

[0060] The second input terminal of the selector is connected to the input signal line, the control terminal receives the third control signal, and the output terminal is used to output the data packet to be forwarded.

[0061] The input terminals of the signal detector are connected to the first signal transmission port (IO1) and the second signal transmission port (IO2) respectively, and are used to detect whether there is a valid signal input on the two ports. The output terminal of the signal detector is connected to the reset terminal (RST) of the counter. When a valid signal is detected, the signal detector outputs a reset signal to the counter, RST is 1, and the counter starts counting. When no signal is detected, RST is 0, the signal detector outputs a low-level reset signal, the counter is cleared and remains in the reset state.

[0062] The input terminal of the counter is connected to the output terminal and the input signal line of the signal detector. It receives a reset signal, records the number of bits of the input signal, and outputs a corresponding control signal. It is used to count according to the transmission timing of the input signal and form a counting signal CNT. The counting signal CNT is used to characterize the timing position of the current input data in the data frame and provides a counting basis for the control signal generator to determine the reading time of the target data packet, the working state of the frame header register, and the switching time of the selector.

[0063] The control signal generator receives the counting signal CNT output from the counter. The output terminals of the control signal generator are connected to the PWM signal generator, the frame header register, and the selector, respectively. Based on the counting signal CNT, it outputs a first control signal C1, a second control signal C2, and a third control signal C3. The first control signal C1 controls the PWM signal generator to read the target data; the second control signal C2 controls the data transmission or latching state of the frame header register; and the third control signal C3 controls the selector to switch between the first input terminal S1 and the second input terminal S2.

[0064] The input of the frame header register is connected to the data register and receives the second control signal C2 output by the control signal generator; the output of the frame header register is connected to the first input S1 of the selector and the signal detector respectively. The frame header register is used to retain and output the frame header information during data deletion and forwarding, so that after the processed data is removed, the frame header can still be reconstructed with the unprocessed subsequent data to form the data frame to be forwarded; the frame header register provides its output signal to the signal detector as one of the detection signals of the signal detector.

[0065] The input terminal of the data register is connected to the input signal line to receive and temporarily store data packets in the input signal. The output terminal of the data register is connected to the PWM signal generator and the frame header register respectively. It is used to provide the display data to be driven to the PWM signal generator and to provide the data entering according to the input timing to the frame header register. The settings of the data register enable the target data to remain stable at the corresponding reading time, which is convenient for PWM drive processing.

[0066] The selector has a first input terminal (S1), a second input terminal (S2), a control terminal, and an output terminal. The first input terminal (S1) is connected to the output terminal of the frame header register and is used to receive the latched data packet and the frame header data output by the frame header register. Its second input terminal (S2) is connected to the input signal line and is used to receive the original input signal (bypass data register). The control terminal of the selector is connected to the output terminal of the third control signal (C3) of the control signal generator. When C3 is 0, the selector selects the data output of the first input terminal (S1). When C3 is 1, the selector selects the input signal of the second input terminal (S2) for direct output. Its output terminal is connected to the input signal line of the next stage.

[0067] The PWM signal generator is connected to the data register and receives the first control signal C1. When the first control signal C1 corresponds to the data packet timing position of the current LED driver circuit feature code, the PWM signal generator reads the target display data in the data register and generates a PWM drive signal with a corresponding duty cycle according to the display data to drive the corresponding LED to output the corresponding grayscale.

[0068] The overall signal flow of the data frame is as follows: the input signal IN is input through the input signal line and then divided into multiple paths. One path is input to a counter, which counts the input signal and outputs a count signal CNT to the control signal generator. The control signal generator outputs a first control signal C1, a second control signal C2, and a third control signal C3 according to the count signal CNT. The first control signal C1 is used to control the PWM signal generator to read the target data in the data register. The second control signal C2 is used to control the data reception, latching, or output status of the frame header register. The third control signal C3 is used to control the selector to switch between the first input terminal S1 and the second input terminal S2. Another input signal enters the data register, which buffers the input data and outputs data to the PWM signal generator and the frame header register respectively. Under the control of the first control signal C1, the PWM signal generator reads the data corresponding to the current LED driving circuit and generates a PWM driving signal based on the read data. Under the control of the second control signal C2, the frame header register processes the frame header data, and its output is connected to the first input S1 of the selector and the signal detector respectively. The signal detector is connected to the input signal line to detect whether there is a signal input, and outputs a reset signal RST to the counter according to the detection result to control the reset and counting process of the counter. The input signal line is also directly connected to the second input S2 of the selector to form a bypass transmission channel. The selector selects the data from the first input S1 or the second input S2 according to the third control signal C3, and outputs the data frame to be forwarded through the output terminal.

[0069] In this embodiment, the frame header length is Hbit, the length of a data packet (DP) is 48bit, the counter starts counting from 0 when the signal is input, and the feature code of the LED driver circuit is I (the value of I is an integer from 1 to K, where K is the number of parallel connections in the group to which the LED driver circuit is located).

[0070] During frame header transmission (counter counts from 0 to 48+H-1), when C2 is 0, the frame header register receives serial input data; when C3 is 0, the selector selects channel S1 and forwards the frame header data to the next stage; when C1 is 0, the PWM signal generator does not read data.

[0071] When the counter reaches 48+H, C2 is 1, and the frame header register latches the frame header data;

[0072] When the counter reaches 48×I+H, C1 becomes 1, triggering the PWM signal generator to read the data packet that matches the feature code of the LED driver circuit from the data register and generate the corresponding PWM drive signal; then when the counter reaches 48×I+H+1, C1 returns to 0, and the PWM signal generator maintains the current output;

[0073] When the counter reaches 48×KH, C2 returns to 0, and the frame header register begins to serially output the latched frame header data; at this time, the current data group has not yet been completely transmitted.

[0074] After the frame header is output in the frame header register (the counter reaches 48×K+H), the current data group is transmitted. At the same time, the frame header data in the frame header register is output. At this time, C3 becomes 1, the selector switches to the S2 channel, and the input signal is directly bypassed and forwarded to the next level. This realizes the deletion of the read data group and no longer forwards it to the next level, and the transparent forwarding of the remaining data frames.

[0075] In this embodiment, data frames are input simultaneously from both the first-level LED driver circuit group and the last-level LED driver circuit group, or from one end with the other as a redundant backup. The controller can input data frames from the first-level LED driver circuit group via DATA1, or from the Lth-level LED driver circuit group via DATA2, or simultaneously from both ends of DATA1 and DATA2, i.e., one end is the primary input and the other is the redundant backup. When the controller sends a data frame via DATA2, the order of the data groups in the data frame is reversed compared to when it is sent via DATA1. Specifically, when sent via DATA1, the order of the data groups in the data frame is DA1, DA2, ..., DAL, corresponding to the first to Lth-level LED driver circuit groups, respectively; when sent via DATA2, the order of the data groups in the data frame is DAL, ..., DA2, DA1, corresponding to the Lth to the first-level LED driver circuit groups, respectively. In this way, regardless of which end the data frame is input from, each LED driver circuit in each LED driver circuit group can read the same data packet content according to its own feature code, realizing seamless switching of bidirectional data transmission.

[0076] In this embodiment, the LED driver circuit continuously detects the data frame and the transmission mode switching of the signal transmission port until a correct data frame is detected at any signal transmission port. Then, it locks the current mode of the signal transmission port and stops switching, performing control data reception and forwarding. After performing a direction switch, the LED driver circuit continuously detects the data frame and monitors the transmission mode of the signal transmission port, repeating the "signal detection—anomaly determination—direction switch" cycle. Specifically, after each direction switch, the LED driver circuit restarts timing and checks whether there is a valid signal input at the port currently in input mode. If an anomaly is detected again, the direction switch is performed again, and this cycle continues until a correct data frame is detected at any signal transmission port. At this point, the LED driver circuit immediately locks the current modes of both signal transmission ports and stops switching, then enters the normal data reception and forwarding working state. Through the above-mentioned cyclic detection and mode locking mechanism, the LED driver circuit can automatically find an available signal input path after a signal transmission link failure, realizing the breakpoint resume function.

[0077] In this embodiment, each LED driver circuit in each LED driver circuit group is configured with a feature code. The feature code is used to determine the data packet to be read by the corresponding LED driver circuit in the first data group of the data frame. Each feature code corresponds to a different data packet in the first data group of the received data frame, so that the data receiving and forwarding circuits of each LED driver circuit can read the corresponding target data packet according to its own feature code. The feature codes of each LED driver circuit in the same LED driver circuit group are different from each other, and the feature codes of different LED driver circuit groups can be the same. Specifically, when different LED driver circuit groups use the same feature code sequence, LED driver circuits in the same arrangement position in each LED driver circuit group can be configured with the same feature code, so that each LED driver circuit group can identify and read data packets according to the same data correspondence rules. When different LED driver circuit groups use different feature code sequences, the feature code arrangement of each LED driver circuit in the group can be independently configured according to the data allocation requirements of each LED driver circuit group, so that the data receiving and forwarding circuits of different LED driver circuits can identify and read the corresponding data packets according to their respective feature code correspondences. Therefore, the feature code configuration method of different LED driver circuit groups is not limited by other LED driver circuit groups. It can be flexibly set according to the actual arrangement of LED driver circuits and data allocation requirements. While ensuring that the data receiving and forwarding circuits of each LED driver circuit can accurately read the corresponding data packets, it improves the data configuration flexibility and adaptability of the LED driver circuit system.

[0078] Specifically, for example, when both the first LED driver circuit group and the second LED driver circuit group include 4 LED driver circuits, the feature code sequence of both groups can be set to "1, 2, 3, 4"; in other embodiments, the feature code sequence of the first LED driver circuit group can be set to "1, 2, 3, 4", and the feature code sequence of the second LED driver circuit group can be set to "1, 3, 2, 4". The data receiving and forwarding circuits of each LED driver circuit still read the data packets corresponding to them according to their own configured feature codes.

[0079] In this embodiment, such as Figure 4 As shown, when a short circuit fault occurs at the signal transmission port of an LED driver circuit, there are four possible scenarios:

[0080] Scenario 1 (Fault ①): When the signal transmission line between the Xth and X+1th LED driver circuit groups is broken (i.e., fault ①) (the value of X ranges from 0 to L), there are two possible scenarios:

[0081] Scenario 1: If, before the signal line is disconnected, the signal transmission ports of the Xth-level LED driver circuit group and the X+1th-level LED driver circuit group connected to the fault point are both in output mode, then the fault will not affect the operation of the entire LED driver circuit system, and all LED driver circuit groups can still receive data normally.

[0082] Scenario 2: If, before the signal line is disconnected, the signal transmission port of the Xth-level LED driver circuit group connected to the fault point is in output mode, while the signal transmission port of the X+1th-level LED driver circuit group is in input mode (i.e., the signal of the X+1th-level LED driver circuit comes from the forwarding of the Xth-level LED driver circuit), then the disconnection of the signal line will cause the input port of the X+1th-level LED driver circuit group to have no signal input. At this time, from the X+1th level to the subsequent LED driver circuits without signal input, the aforementioned cyclic detection and direction switching process will be executed in sequence. After several switching cycles, all of them will switch to receiving data sent by DATA2. Thus, all LED driver circuit groups can resume normal data reception, realizing the breakpoint resume function, thereby ensuring that the operation of the entire system is not affected.

[0083] Scenario 2 (Fault ②): When the signal transmission port (IO1 or IO2) of a certain LED driver circuit is shorted to GND, the signal of the node where the port is located is shorted to ground, which is equivalent to the signal being disconnected at the shorting point. The input port of the subsequent LED driver circuit group connected to the shorted port will not detect a valid signal, triggering the aforementioned cyclic detection and direction switching process. Finally, the LED driver circuit receives the control signal from another direction.

[0084] Scenario 3 (Fault ③): When the signal transmission port (IO1 or IO2) of a certain LED driver circuit is shorted to VDD, the node where the port is located will remain at a high level. The continuously high level input will also be judged by the LED driver circuit as a signal transmission abnormality (because the level does not change), thereby triggering a direction switch. It is equivalent to the signal being disconnected at the short circuit point. The subsequent processing method is the same as in Scenario 2.

[0085] Scenario 4 (Fault ④): When a single LED driver circuit in a certain LED driver circuit group falls off or is damaged (Fault ④), since the LED driver circuits in the same LED driver circuit group are connected in parallel, the fall off or damage of a single LED driver circuit will not affect the signal reception and forwarding of other LED driver circuits in the group, but will only cause the single LED driver circuit to fail to work. Through the above mechanism, the present invention greatly improves the reliability of the LED driver circuit system under various fault scenarios.

[0086] Further, please refer to Figure 6Taking the i-th LED driver circuit in any level of LED driver circuit group as an example, the feature code ID of the i-th LED driver circuit is i, where i is an integer from 1 to K. The i-th LED driver circuit determines the timing position of the corresponding data packet DPi according to the feature code. The counter generates a counting signal CNT according to the input signal and outputs it to the control signal generator. When the control signal generator CNT reaches the corresponding position of DPi, it controls the PWM signal generator to read the corresponding data in the data register through the first control signal C1. For data packets that do not correspond to the feature code of the current LED driver circuit, the current LED driver circuit does not perform a reading operation. If the input data also contains data packets that exceed the processing range of the current LED driver circuit group, this part of the data is not read or deleted, but continues to be output through the pass-through path of the selector.

[0087] Specifically, with Figure 6 For example, the input signal IN includes a frame header FH and sequentially arranged data packets DP1, DP2, ..., DPi, ..., DPK, and may continue to include other data beyond the current processing level after DPK. The frame header FH is used to identify the start position of the data frame, and each data packet is used to carry the display data of the corresponding LED driver circuit; in one embodiment, both the frame header FH and a single data packet DP can use a 48-bit data unit. A signal detector is connected to the input signal line to detect whether there is a signal input and outputs a reset signal RST to the counter; the counter counts according to the transmission timing of the input signal in the counting state and forms a counting signal CNT, which is then output to the control signal generator.

[0088] During input data transmission, the control signal generator generates a first control signal C1, a second control signal C2, and a third control signal C3 based on the counter output signal CNT. The first control signal C1 is used to control the PWM signal generator to read the data packet corresponding to the current LED driving circuit. When CNT reaches the timing position of the data packet DPi corresponding to the feature code ID=i, the control signal generator causes C1 to enter the reading state. The PWM signal generator reads the display data corresponding to DPi from the data register and generates a PWM drive signal with a corresponding duty cycle based on the read display data. After the reading is completed, C1 returns to the non-reading state, allowing the PWM signal generator to maintain its current output.

[0089] The second control signal C2 is used to control the data transmission and latching state of the frame header register. After the frame header FH enters the frame header register, the control signal generator controls the state of C2 according to CNT, so that the frame header FH is retained during the processing of the current level target data, and the frame header output is restored when the data frame to be forwarded needs to be output. The output of the frame header register is also connected to the signal detector to provide the signal output through the frame header register to the signal detector, so as to cooperate with the signal detector for input status detection and count reset control.

[0090] The third control signal C3 is used to control the signal path of the selector. When the current stage is processing target data, the selector can select the first input terminal S1, allowing the signal output from the frame header register to enter OUT. When it is necessary to pass through subsequent data that has not been processed by the current stage, the control signal generator changes the state of C3 according to CNT, causing the selector to switch to the second input terminal S2, directly outputting the subsequent data in the input signal IN. By switching between S1 and S2, OUT can form a data frame to be forwarded, containing the frame header and data that has not been deleted by the current stage.

[0091] The advantages of this application are:

[0092] 1. This application adopts a bidirectional signal transmission structure with an automatic fault switching mechanism, which can automatically switch the signal transmission direction to bypass the fault area when common faults such as line disconnection, port short circuit, or single chip damage occur at any node. This ensures that all normal LED driver circuits can receive control data normally and will not cause display abnormalities in the entire screen or entire area, significantly improving the fault tolerance and operational stability of the LED display system.

[0093] 2. This application adopts a hierarchical data transmission scheme of "read, delete and forward". After each LED driver circuit group reads the data, it removes the read data group and then transmits it to the next level. As the transmission level advances, the data frame length gradually shortens, reducing the occupation of transmission bandwidth by invalid data. Compared with the traditional full data forwarding scheme, it significantly reduces data transmission redundancy, improves data transmission efficiency, and supports display output with higher refresh rates.

[0094] 3. The LED driver circuits in the same level LED driver circuit group adopt a parallel structure design. When a single LED driver circuit in the group is detached or damaged, it will not affect the normal operation of other driver circuits in the same group. At the same time, it only needs to occupy one cascade transmission channel. Compared with the fully parallel structure, it greatly reduces the number of signal transmission ports and wiring, balances the reliability of the system and the wiring complexity, and adapts to the application requirements of large-size splicing LED displays.

[0095] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A bidirectional transmission series-parallel combined LED driving circuit system, characterized in that, The system includes a controller and L LED driver circuit groups connected in series. Each LED driver circuit group includes K LED driver circuits connected in parallel, and each LED driver circuit is provided with a first signal transmission port and a second signal transmission port with data transmission function; wherein K and L are both natural numbers greater than or equal to 1. Each LED driver circuit in the LED driver circuit group has a corresponding feature code. Each data frame output by the controller includes a frame header and L data groups. Each data group includes K data packets corresponding to the LED driver circuit group. The frame header is used to verify each data frame. The LED driver circuit in the LED driver circuit group verifies and reads the matching data packets according to the corresponding feature code. Both the first signal transmission port and the second signal transmission port can dynamically switch the transmission mode to input mode or output mode. The controller outputs data frames to the first LED driving circuit group or the Lth LED driving circuit group. The LED driving circuit can monitor the transmission status of the data frame and switch the input mode or output mode of the first signal transmission port and the second signal transmission port. When the LED driving circuit detects an abnormality in the current input signal transmission, it controls the first signal transmission port or the second signal transmission port to switch to another mode so that the data frame is transmitted in another direction. The LED driving circuit includes a data receiving and forwarding circuit. After receiving the correct data frame, each LED driving circuit in any LED driving circuit group reads the corresponding data packet from the current data frame according to the feature code of its own LED driving circuit, deletes the data group already read in the received data frame, and forwards it to the next level LED driving circuit group.

2. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 1, characterized in that, When the first signal transmission port or the second signal transmission port is in input mode, if the LED driving circuit does not detect data within a preset waiting time, detects that the level has not changed within a preset waiting time, or receives T consecutive data frames with incorrect format, it switches the input and output modes of the two signal transmission ports, switching the signal transmission port in input mode to output mode and the signal transmission port in output mode to input mode, where T is a natural number ≥ 1.

3. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 1, characterized in that, At any given time, only one of the first signal transmission ports and the second signal transmission port of each LED driver circuit is in input mode, while the other port is in output mode.

4. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 1, characterized in that, When the number of data groups in the data frame is greater than L, each LED driver circuit group reads the first data group and forwards the remaining data groups transparently; when the number of data packets in any data group is greater than K, each LED driver circuit in the LED driver circuit group only reads the target data packet corresponding to its own feature code and forwards the remaining data packets transparently.

5. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 4, characterized in that, The data receiving and forwarding circuit includes an input signal line connecting the first signal transmission port and the second signal transmission port, a data register, a frame header register, a PWM signal generator, a signal detector, a counter, a control signal generator, and a selector; The input terminal of the counter is connected to the input signal line, and the output terminal is connected to the control signal generator, which is used to count the input signal and output a counting signal. The output terminal of the control signal generator is connected to the PWM signal generator, the frame header register and the selector respectively, and outputs a first control signal, a second control signal and a third control signal according to the counting signal; The input terminal of the data register is connected to the input signal line, and the output terminal is connected to the PWM signal generator and the frame header register respectively. The PWM signal generator receives the first control signal and generates a PWM drive signal based on the data output from the data register. The frame header register receives a second control signal, its input is connected to the data register, and its output is connected to the first input of the selector and the signal detector. The signal detector is also connected to the input signal line to detect whether there is a signal input and to output a reset signal to the counter; The second input terminal of the selector is connected to the input signal line, the control terminal receives the third control signal, and the output terminal is used to output the data packet to be forwarded.

6. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 1, characterized in that, The data frames are input simultaneously from the first-stage LED driver circuit group and the last-stage LED driver circuit group, or input from one end with the other end as a redundant backup.

7. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 1, characterized in that, The LED driving circuit continuously detects the data frame and the transmission mode switching of the signal transmission port. When any signal transmission port detects a correct data frame, it locks the current mode of the signal transmission port and stops switching, and then controls the reception and forwarding of data.

8. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 1, characterized in that, The data packet carries display data corresponding to the LED driver circuit, and the display data includes red grayscale data, green grayscale data, and blue grayscale data.

9. The LED driving circuit system with bidirectional transmission series-parallel combination according to claim 1, characterized in that, Each LED driver circuit in each LED driver circuit group is configured with a feature code, which is used to determine the data packet to be read by the corresponding LED driver circuit in the first data group of the data frame. Each feature code corresponds to a different data packet in the first data group of the received data frame, so that each LED driver circuit can read the corresponding target data packet according to its own feature code. The feature codes of each LED driver circuit in the same LED driver circuit group are different from each other, and the feature codes of different LED driver circuit groups can be the same.

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