WO2013170460A1

WO2013170460A1 - Led display screen constant current drive control system and output current control method therefor

Info

Publication number: WO2013170460A1
Application number: PCT/CN2012/075616
Authority: WO
Inventors: 胡家同
Original assignee: 深圳市摩西尔电子有限公司
Priority date: 2012-05-16
Filing date: 2012-05-16
Publication date: 2013-11-21

Abstract

Disclosed are an LED display screen constant current drive control and an output current control method therefor. The LED display screen constant current drive control system comprises an N-number of cascaded LED constant current driver chips, a clock (CLK) terminal, a data latch (LE) terminal, and an output enable (OE) terminal. Clock (CLK) pins of the N-number of LED constant current driver chips are connected with each other and are convergedly connected to the clock (CLK) terminal; data latch (LE) pins of the N-number of LED constant current driver chips are connected with each other and are convergedly connected to the data latch (LE) terminal; output enable (OE) pins of the N-number of LED constant current driver chips are connected with each other and are convergedly connected to the output enable (OE) terminal. Any two or more terminals among the three terminals, namely the output enable (OE) terminal, the data latch (LE) terminal, and the clock (CLK) terminal, serve as current control signal input terminals for input of a current control signal to control an output current of output (OUT1-OUTM) pins of the N-number of LED constant current driver chips. DRAWING: Fig. 1: AA LED array

Description

Constant current driving control system for LED display screen and output current control method thereof

The invention relates to an LED driving control technology, in particular to a constant current LED display driving control system with a quick setting function and a control data setting method thereof.

Background technique

The display is one of the important media for people to receive a variety of information. As a multimedia display terminal, the display has an important indicator, that is, the display's quick response capability. The current control signals of the traditional LED constant current driving chip are serially transmitted by the shift register module. Since the shift register module uses words as the processing unit, the longer the word length, the longer the processing time; usually the current control signal The number of bits is less than the word length, so that the data transmitted less than the word length also needs to pass the transmission time of the entire word, which limits the transmission speed of the data information smaller than the word length, especially when multiple LED constant current driving chips are cascaded. The delay is more obvious. The more the cascading, the more serious the delay, the lower the data transmission efficiency, the faster the response capability of the LED display control system, and the system function is not easy to expand.

Summary of the invention

In view of this, it is necessary to provide a LED display constant current drive control system and an output current control method thereof in response to the above problems.

The invention adopts the following technical solutions: A LED display constant current driving control system, comprising N cascaded LED constant current driving chips, a clock CLK end, a data latch LE end, an output enable OE end, wherein the first LED The data output DO pin of the constant current driving chip is connected to the data input DI pin of the second LED constant current driving chip, and the data output DO pin of the second LED constant current driving chip and the data input of the third LED constant current driving chip The DI pins are connected to be connected to the Nth LED driving chip; the clock CLK pins of the N LED constant current driving chips are connected to each other and connected to the clock CLK terminal; the N LED constant current driving The data latches LE pins of the chip are connected to each other and connected to the data latch LE end; the output enable OE pins of the N LED constant current driving chips are connected to each other, and are connected to the output enable OE The M output pins OUT1 -OUTM of the N LED constant current driving chips are connected to their respective controlled LED arrays; the power supply VDD pins of the N LED constant current driving chips are connected to the power supply; The ground GND pin of the N LED constant current driving chip is connected to the power ground The external resistors REXT pins of the N LED constant current driving chips pass through respective current settings The resistor is connected to the power ground; the output enable OE terminal, the data latch LE terminal, and the clock CLK terminal are used as current control signal input terminals for inputting a current control signal to control the N LED constant current driver chip output OUT1 - OUTM pin output current.

In the LED drive control system of the present invention, the control state data of the output OUT1 - OUTM pins of the respective N LED constant current drive chips are input from the data input DI of the first LED constant current drive chip.

In the LED drive control system of the present invention, the current control signal includes clock and current control data.

The invention also provides an output current control method for a constant current drive control system of an LED display screen, wherein the LED display constant current drive control system comprises N cascaded LED constant current driving chips, a clock CLK terminal, and a data latch The LE end and the output enable OE end, wherein the data output DO pin of the first LED constant current driving chip is connected to the data input DI pin of the second LED constant current driving chip, and the data output DO of the second LED constant current driving chip The pin is connected to the data input DI pin of the third LED constant current driving chip, so as to be cascaded to the Nth LED driving chip; the clock CLK pins of the N LED constant current driving chips are connected to each other, and connected to the a clock CLK terminal; the data latch LE pins of the N LED constant current driving chips are connected to each other, and are connected to the data latch LE end; the output of the N LED constant current driving chips is enabled OE The legs are connected to each other and connected to the output enable OE terminal; the M output pins OUT1 - OUTM of the N LED constant current driving chips are connected to their respective controlled LED arrays; the N LED constant current driving chip The power VDD pin is connected to the power supply; the ground GND pin of the N LED constant current driving chips is connected to the power ground; the external resistors REXT pins of the N LED constant current driving chips are respectively set by respective currents. The resistor is connected to the power ground; when the current control signal is input, the current control signal is input by using any one or more of the three terminals of the output enable OE terminal, the data latch LE terminal, and the clock CLK terminal, and the N LEDs are controlled. Constant current drive chip output OUT1 - OUTM pin output current.

In the above method: the current control signal includes clock and current control data; the LED display constant current drive control system operates in a non-current adjustment state and a current adjustment state; in the non-current adjustment state, if in the clock When the current control data is high at the rising edge of the signal, it enters the current adjustment state. After entering the current adjustment state, the current control data is written into the LED display. Each LED constant current driving chip in the flow driving control system; after completion, the LED display constant current driving control system exits the current adjustment state; the LED constant current driving control system of each LED constant current driving chip is based on The current control data realizes adjustment of an output current of N driving outputs OUT1 - OUTM pins of each LED constant current driving chip in the LED display constant current driving control system.

The method may also be: the current control signal includes a clock and a level; and the LED display constant current drive control system includes two states of operation: a non-current adjustment state and a current adjustment state;

In the non-current adjustment state, if the level is high at the rising edge of the clock signal, the current adjustment state is entered, and after entering the current adjustment state, the LED constant current driving chips in the LED display constant current drive control system pass The clock counts the level width; after completion, the LED constant current driving chip in the LED display constant current driving control system exits the current adjustment state; the LED display constant current driving control system LED constant current driving The chip realizes adjustment of the output current of the N driving outputs OUT1 - OUTM pins of the LED constant current driving chips in the LED display constant current driving control system according to the count value.

The beneficial effects of the invention are as follows: Since the control data of the output current is not obtained after serial serialization by the chip, it is not limited by the word length of the control word, so that the current control speed is increased, and the more the driver chip cascades, the effect is obtained. More obvious, this improves the utilization of the hardware, makes the system's functions easy to expand, and the response performance of the LED control system is improved.

DRAWINGS

1 is a schematic diagram of a constant current drive control system of an LED display screen (the chip output is taken as an example of 16 bits); FIG. 2 is a timing diagram of control data data in the prior art for transmitting OUT0_OUT15 (chip output is 16 bits as an example);

3 is a timing diagram of a transmission current control signal in the prior art;

4 is a timing chart of an output current control method of the first embodiment of the present invention;

Figure 5 is a timing chart of the output current control method of the second embodiment of the present invention.

detailed description

The invention will now be further described with reference to the drawings and specific embodiments.

Figure 1 is a schematic diagram of the LED drive control system (the chip output is 16 bits as an example). As can be seen from the figure, N LED constant current drive chips are cascaded, and the data output of the first LED constant current drive chip is cited. The pin DO is connected to the data input pin DI of the second LED constant current driving chip, and the data output pin DO of the second LED constant current driving chip is connected to the data input pin DI of the third LED constant current driving chip, so that the cascading To the Nth LED driver chip; the clocks of the N LED constant current driver chips are connected to each other and connected to the clock CLK terminal; the data latches of the N LED constant current driver chips are connected to each other, and connected To the data latch LE end; N LED constant current driver chip output enable OE pin interconnection, sink to the output enable OE terminal; N LED constant current driver chip M output pin OUT1 - OUTM Connected to the LED array; N LED constant current driving chip power pin VDD is connected to the power supply; N LED constant current driving chip ground pin GND is connected to the power ground; N LED constant current driving chip respective external resistor The pin REXT is connected to the power ground through the respective current setting resistors. When the current control signal is input, the output enable OE terminal, the data latch LE terminal, and the clock CLK terminal are used as the current control signal input. Terminal for inputting electricity The control signal controls the output current of the output pins OUT1_OUTM of the N LED constant current driving chips; since the current control signal is no longer serially input from the data input terminal DI, the clock CLK terminal and the data latch LE end are directly used. The output enables the OE terminal to transmit, so the current control signal reaches the cascading LED driver chip almost simultaneously; Figure 2 and Figure 3 show the prior art. It can be seen that if there are 4 chips connected in series, 64 CLKs are required. The current setting is completed; thus, the present invention is much faster than cascading serial input from the data input terminal DI in the prior art shown in FIG. 3, which improves the system response performance and makes full use of hardware resources.

In the above scheme, the control state data of the respective output pins OUT1_OUTM of the N LED constant current driving chips are input from the data input terminal DI of the first LED constant current driving chip.

In the above scheme, the output current is controlled by the following control method:

When inputting the current control signal, use any two or more terminals of the output enable OE terminal, the data latch LE, and the clock CLK terminal as the current control signal input terminal to control the output pin OUT1 of the N LED constant current driving chips. — OUTM output current.

In the above method, it can be:

The current control signal includes clock and current control data: The LED display constant current drive control system operates in a non-current adjustment state and a current adjustment state;

In the non-current adjustment state, if the current control data is high at the rising edge of the clock signal, then enter Current adjustment status. After entering the current adjustment state, the subsequent current control data is written into each LED constant current driving chip in the LED display constant current driving control system, and the LED display constant current driving control system exits the current adjustment state after completion; the LED display constant current Each LED constant current driving chip in the driving control system realizes adjustment of the output current of the N driving output pins OUT1 - OUTM of each LED constant current driving chip in the LED display constant current driving control system according to the current control data.

As shown in Figure 4, the current control signal has 6 bits as an example. The system includes two working states: (1) non-current adjustment state, and (2) current adjustment state.

In the non-current adjustment state, if LE is high at the rising edge of CLK (DO is high), the current adjustment state is entered. After entering the current adjustment state, the subsequent 6 bits are written into the LED constant current driving chip, and the LED constant current driving is performed. The chip adjusts the output current of OUT1 -OUTN according to these 6 bits. This method can call up to 64 current values. After the current adjustment state has passed 7 CLKs, it returns to the non-current regulation state.

In the above method, it can also be:

The current control signal includes a clock and a level;

The LED display constant current drive control system includes two working states: a non-current adjustment state and a current adjustment state.

In the non-current adjustment state, if the level is high at the rising edge of the clock signal, the current adjustment state is entered, and after entering the current adjustment state, each LED constant current driving chip in the LED display constant current driving control system passes the clock to power Flat width count, after completion, LED constant current drive control system LED constant current drive chip exit current adjustment state; LED display constant current drive control system LED constant current drive chip according to the count value to achieve constant LED display The output current of the N drive output pins OUT1_OUTM of each LED constant current drive chip in the flow drive control system is adjusted.

As shown in Figure 5, the system includes two operating states: (1) non-current adjustment state, and (2) current regulation state.

In the non-current adjustment state, if LE is high at the rising edge of CLK, the current adjustment state is entered. After entering the current adjustment state, the high level of LE is counted by CLK, and the LED constant current driving chip drives OUT1_OUTN according to the count value. The output current is adjusted. This method can call up to 6 current values. After the current adjustment state passes 7 CLKs, it returns to the non-current adjustment state. The above-described embodiments are merely illustrative of several embodiments of the invention, but are not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

claims

1. An LED display constant current drive control system, including N cascaded LED constant current drive chips, a clock CLK terminal, a data latch LE terminal, and an output enable OE terminal. It is characterized by: The first LED constant current driver chip The data output DO pin of the current driver chip is connected to the data input DI pin of the second LED constant current driver chip, and the data output DO pin of the second LED constant current driver chip is connected to the data input DI of the third LED constant current driver chip. The pins are connected, thus cascading to the Nth LED driver chip; The clock CLK pins of the N LED constant current driver chips are connected to each other and connected to the clock CLK terminal; The clock CLK pins of the N LED constant current driver chips The data latch LE pins are connected to each other and connected to the data latch LE terminal; the output enable OE pins of the N LED constant current driver chips are connected to each other and connected to the output enable OE terminal; The M output pins OUT1 - OUTM of each of the N LED constant current drive chips are connected to the LED arrays they control respectively; the power supply VDD pins of the N LED constant current drive chips are connected to the power supply; the N The GND pin of the LED constant current driver chip is connected to the power supply ground; the external resistor REXT pins of each of the LED constant current driver chips are connected to the power supply ground through their respective current setting resistors; the output enable OE terminal, data Any two or more of the three terminals of the latch LE terminal and the clock CLK terminal are used as current control signal input terminals to input the current control signal to control the output of the N LED constant current driver chips OUT1-OUTM pins. current.

2. The LED display screen constant current drive control system according to claim 1, characterized in that, the control status data of the output OUT1-OUTM pins of each of the N LED constant current drive chips is obtained from the first LED constant current drive chip. The data input DI terminal of the stream driver chip is input.

3. The LED display screen constant current drive control system according to claim 1 or 2, characterized in that the current control signal includes a clock and current control data.

4. An output current control method of an LED display constant current drive control system. The LED display constant current drive control system includes N cascaded LED constant current drive chips, a clock CLK terminal, a data latch LE terminal, The output enable OE terminal, where the data output DO pin of the first LED constant current driver chip is connected to the data input DI pin of the second LED constant current driver chip, and the data output DO pin of the second LED constant current driver chip is connected to The data input DI pin of the third LED constant current driver chip is connected to the Nth LED driver chip; the clock CLK pins of the N LED constant current driver chips are connected to each other and concatenated to the clock CLK. terminal; the data latch LE pins of the N LED constant current driver chips are connected to each other and connected to the data latch LE terminal; the data latch LE pins of the N LED constant current driver chips are The output enable OE pins are connected to each other and connected to the output enable OE terminal; the M output pins OUT1 to OUTM of each of the N LED constant current driver chips are connected to the LED arrays they control respectively; the N The power supply VDD pins of the N LED constant current drive chips are connected to the power supply; the ground GND pins of the N LED constant current drive chips are connected to the power supply ground; the external resistor REXT pins of the N LED constant current drive chips are connected to the power supply ground. The pins are connected to the power ground through their respective current setting resistors;

It is characterized in that: when the current control signal is input, any two or more terminals among the three terminals of the output enable OE terminal, the data latch LE terminal, and the clock CLK terminal are used to input the current control signal to control the constant current of the N LEDs. The output OUT1 of the driver chip is the output current of the OUTM pin.

5. The output current control method of the LED display constant current drive control system according to claim 4, characterized by:

Current control signals include clock and current control data;

The LED display constant current drive control system includes two working states: non-current adjustment state and current adjustment state;

In the non-current adjustment state, if the current control signal is high at the rising edge of the clock signal, it enters the current adjustment state. After entering the current adjustment state, the current control signal is written into each of the LED display constant current drive control systems. LED constant current drive chip; after completion, the LED display constant current drive control system exits the current adjustment state; each LED constant current drive chip in the LED display constant current drive control system implements control according to the current control signal. Adjustment of the output currents of the N drive output OUT1-OUTM pins of each LED constant current drive chip in the LED display constant current drive control system.

6. The output current control method of the LED display constant current drive control system according to claim 4, characterized by:

The current control signal includes clock and level;

In the non-current adjustment state, if the level is high at the rising edge of the clock signal, it enters the current adjustment state. After entering the current adjustment state, each LED constant current drive chip in the LED display constant current drive control system passes The clock counts the level width; after completion, each LED constant current drive chip in the LED display constant current drive control system exits the current adjustment state; the LED display constant current drive control system Each LED constant current drive chip in the control system realizes adjustment of the output current of the N drive output OUT1-OUTM pins of each LED constant current drive chip in the LED display constant current drive control system according to the count value.