CN109377937B

CN109377937B - LED driving method and driving circuit

Info

Publication number: CN109377937B
Application number: CN201811315355.4A
Authority: CN
Inventors: 梁宁
Original assignee: Shenzhen Konka Electronic Technology Co Ltd
Current assignee: Shenzhen Konka Electronic Technology Co Ltd
Priority date: 2018-11-06
Filing date: 2018-11-06
Publication date: 2020-12-22
Anticipated expiration: 2038-11-06
Also published as: CN109377937A

Abstract

The invention discloses an LED driving method and a driving circuit, wherein the LED driving method comprises the following steps: receiving data sent by a front-end circuit; decoding data sent by a front-end circuit and outputting a decoding command; carrying out corresponding parameter setting or driving operation on the LED circuit according to the decoding command; and receiving a synchronous pulse signal of the front-end circuit and driving the LED circuit to be turned on/off. The LED driving method provided by the invention enables the LED circuit to display without refreshing according to bits, only needs to transmit data once when displaying one field, and can realize multi-bit gray scale display through the rear-end LED driving circuit, thereby reducing data throughput and improving LED display efficiency; and even if the field frequency doubling technology is adopted, the data throughput is unchanged.

Description

LED driving method and driving circuit

Technical Field

The invention relates to the technical field of LED display, in particular to an LED driving method and a driving circuit.

Background

Because the Light Emitting Diode (LED) display screen has the advantages of bright color, high brightness, long service life, stable and reliable work and the like, the LED display screen is widely applied to many industries. For example, in public places such as stations, docks, markets, banks and the like, the LED display screen can be used for issuing real-time information and timely and accurately transmitting information needing to be paid attention to the public.

The LED display screen comprises millions or even tens of millions of LEDs, the LEDs are directly connected with a driving chip, the driving chip generally adopts a constant current driving chip with serial-parallel conversion, display is refreshed according to bits, and the data transmission efficiency is very low. Taking 12-bit gray scale display as an example, each field needs to be refreshed at least 12 times, and a complete picture with correct gray scale can be formed only by 12 times of gray scale accumulation, namely 12-bit gray scale accumulation, of 1-bit gray scale display each time. In the process, the data throughput is large, the efficiency is low, and if the field frequency doubling technology is adopted, the data throughput is multiplied, so that the efficiency is lower. Meanwhile, the high data throughput means high circuit overhead, thereby increasing circuit cost and design complexity.

Thus, the prior art has yet to be improved and enhanced.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an LED driving method and a driving circuit, which can achieve multi-bit gray scale display of a circuit by only transmitting data once, thereby reducing data throughput and improving efficiency of LED display.

In order to achieve the purpose, the invention adopts the following technical scheme:

an LED driving method, comprising the steps of:

receiving data sent by a front-end circuit;

decoding data sent by a front-end circuit and outputting a decoding command;

carrying out corresponding parameter setting or driving operation on the LED circuit according to the decoding command;

and receiving a synchronous pulse signal of the front-end circuit and driving the LED circuit to be turned on/off.

In the LED driving method, after the step of receiving data transmitted by the front-end circuit, the method further includes the steps of:

the data transmitted from the front-end circuit is decoded in a group of 24 bits per received data.

In the LED driving method, the decoding the data sent by the front-end circuit and outputting a decoding command specifically includes:

selecting a command word and an identification code of the decoded data;

and judging the type of the command word according to the identification code of the decoded data and outputting a corresponding decoding command.

In the LED driving method, the step of selecting the command word and the identification code of the decoded data specifically includes:

forming the 1 st bit to the 16 th bit of the decoded data into a command word;

the 17 th bit and the 18 th bit of the decoded data are combined into an identification code.

In the LED driving method, the step of determining the type of the command word and outputting the corresponding decoding command by the identification code of the decoded data specifically includes:

when the identification code is equal to 01, the command word is a gating word, and a gating word command is output;

when the identification code is equal to 10, the command word is a data word, and a data word command is output;

when the identification code is equal to 11, the command word is a setting word, and a setting word command is output;

when the identification code is equal to 00, the command word is ignored.

In the LED driving method, the step of performing corresponding parameter setting or driving operation on the LED circuit according to the decoding command specifically includes:

when the output decoding command is a gating word command, controlling whether the part of the corresponding LED circuit is lighted or not according to the gating word command;

when the output decoding command is a data word command, setting the gray value of the LED circuit according to the data word command;

when the output decoding command is a set word command, the display gray scale level and the field frequency multiplication number of the LED circuit are set according to the set word command.

In the LED driving method, when the output decoding command is a set word command, the step of setting the display gray scale level and the field frequency multiple of the LED circuit according to the set word command specifically includes:

when the output decoding command is a set word command, setting the display gray level of the LED circuit according to the value of the lower 8 bits of the set word command;

when the output decoding command is a set word command, the field frequency multiplication frequency of the LED circuit is set according to the value of the upper 8 bits of the set word command.

An LED driving circuit comprising an LED circuit composed of a plurality of LEDs and a driving circuit, the driving circuit comprising:

the data interface module is used for receiving data sent by the front-end circuit;

the decoding module is used for decoding data sent by the front-end circuit and outputting a decoding command;

the driving module is used for receiving the decoding command output by the decoding module and performing driving operation;

a setting module for receiving the decoding command output by the decoding module and setting parameters;

the data interface module is connected with the decoding module, the decoding module is further connected with the driving module and the setting module, and the driving module is further connected with the LED circuit.

In the LED driving circuit, the decoding command comprises a gating word command, a setting word command and a data word command.

In the LED driving circuit, the data interface module receives data sent by the front-end circuit by using an I2C interface or an SPI interface.

Compared with the prior art, the LED driving method and the LED driving circuit provided by the invention have the advantages that the LED driving method comprises the following steps: receiving data sent by a front-end circuit; decoding data sent by a front-end circuit and outputting a decoding command; carrying out corresponding parameter setting or driving operation on the LED circuit according to the decoding command; and receiving a synchronous pulse signal of the front-end circuit and driving the LED circuit to be turned on/off. The LED driving method provided by the invention enables the LED circuit to display without refreshing according to bits, only needs to transmit data once when displaying one field, and can realize multi-bit gray scale display through the rear-end LED driving circuit, thereby reducing data throughput and improving LED display efficiency; and even if the field frequency doubling technology is adopted, the data throughput is unchanged.

Drawings

Fig. 1 is a schematic block diagram of an LED driving circuit provided in the present invention.

Fig. 2 is a flowchart of an LED driving method provided in the present invention.

FIG. 3 is a schematic structural diagram of decoding data and decoding commands according to the present invention.

Fig. 4 is a flowchart of step S200 in the LED driving method provided by the present invention.

Fig. 5 is a flowchart of step S210 in the LED driving method provided by the present invention.

Fig. 6 is a flowchart of step S220 in the LED driving method provided by the present invention.

Fig. 7 is a flowchart of step S300 in the LED driving method provided by the present invention.

Fig. 8 is a flowchart of step S330 in the LED driving method provided by the present invention.

Fig. 9 is a circuit schematic diagram of a driving module provided in the present invention.

Fig. 10 is a circuit diagram of a driving sub-circuit provided in the present invention.

Fig. 11 is a schematic diagram of an operating waveform of a PWM module according to a first embodiment of the present invention.

Fig. 12 is a schematic diagram of an operating waveform of a PWM module according to a second embodiment of the present invention.

Detailed Description

The present invention provides a method and a circuit for driving an LED, and in order to make the objects, technical solutions, and effects of the present invention clearer and clearer, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1, a schematic block diagram of an LED driving circuit provided by the present invention includes an LED circuit (not shown in the figure) composed of a plurality of LEDs and a driving circuit for driving the LED circuit to emit light, and the driving circuit includes:

a data interface module 10 for receiving data sent by the front-end circuit;

a decoding module 20 for decoding the data sent by the front-end circuit and outputting a decoding command;

a driving module 30 for receiving the decoding command outputted by the decoding module and performing driving operation;

a setting module 40 for receiving the decoding command output by the decoding module and setting parameters;

the data interface module 10 is connected to the decoding module 20, the decoding module 20 is further connected to the driving module 30 and the setting module 40, and the driving module 30 is further connected to the LED circuit.

Referring to fig. 2, a flowchart of an LED driving method provided by the present invention is shown, where the LED driving method includes the steps of:

s100, receiving data sent by a front-end circuit;

s200, decoding data sent by the front-end circuit and outputting a decoding command;

s300, carrying out corresponding parameter setting or driving operation on the LED circuit according to the decoding command;

and S400, receiving a synchronous pulse signal of the front-end circuit and driving the LED circuit to be turned on/off.

By the LED driving method and the LED driving circuit, the display of the LED circuit does not need to be refreshed according to bits, and the multi-bit gray scale display can be realized by the driving circuit at the rear end only by transmitting data once by the front end circuit every time one field is displayed, so that the data throughput is reduced, and the LED display efficiency is improved. The data throughput refers to the number of data (usually measured in bits or bytes) successfully transmitted by a circuit facility per unit time; the front-end circuit is a single-chip microcomputer control circuit for controlling the display of the LED circuit.

Further, after step S100, the method further includes the steps of:

That is, after the data interface module receives the data sent by the front-end circuit, the data interface module receives the data of 3 bytes (24 bits) to form once decoded data and transmits the once decoded data to the decoding part. Referring to FIG. 3, a schematic diagram of a structure of decoded data and decoded commands according to the present invention is shown, wherein the decoded data is represented by b₀To b₂₃I.e. b 23:0]For a total of 24 bits of data. Preferably, the data interface module receives data sent by the front-end circuit by using an I2C interface or an SPI interface.

Referring to fig. 4, the step S200 specifically includes:

s210, selecting a command word and an identification code of the decoded data;

s220, judging the type of the command word according to the identification code of the decoded data and outputting a corresponding decoding command.

The decoding module extracts command words and identification codes in the decoded data through a preset decoding rule and finally outputs a decoding command, so that corresponding parameter setting or driving operation is carried out on the LED circuit. The decode commands may specifically include a strobe word command, a set word command, and a data word command.

Referring to fig. 3 and fig. 5, the step S210 specifically includes:

s211, forming the 1 st bit to the 16 th bit of the decoded data into a command word;

s212, the 17 th bit and the 18 th bit of the decoded data are combined into an identification code.

That is, in FIG. 5, the lower 16 bits b [15:0] of the decoded data are selected to form a command word, and the 17 th bit and the 18 th bit b [17:16] of the decoded data are selected as identification codes.

Referring to fig. 3 and fig. 6, the step S220 specifically includes:

s221, when the identification code is equal to 01, the command word is a gating word, and a gating word command is output;

s222, when the identification code is equal to 10, the command word is a data word, and a data word command is output;

s223, when the identification code is equal to 11, the command word is a setting word, and a setting word command is output;

s224, when the identification code is equal to 00, ignoring the command word.

That is, when the identification code is equal to 01, the decoded command is a strobe command s [15:0 ]; when the identification code is equal to 10, the command is decoded into a data word command d [15:0 ]; when the identification code is equal to 11, the decoded command is a set word command p [15:0 ].

In a further embodiment, referring to fig. 7, the step S300 specifically includes:

s310, when the output decoding command is a gating word command, controlling whether a part of the corresponding LED circuit is lighted or not according to the gating word command;

s320, when the output decoding command is a data word command, setting the gray value of the LED circuit according to the data word command;

s330, when the output decoding command is a set word command, the display gray level and the field frequency multiplication number of the LED circuit are set according to the set word command.

Referring to fig. 8, the step S330 specifically includes:

s331, when the output decoding command is a set word command, setting the display gray level of the LED circuit according to the value of the lower 8 bits of the set word command;

and S332, when the output decoding command is a set word command, setting the field frequency multiplication frequency of the LED circuit according to the value of the upper 8 bits of the set word command.

In a more specific embodiment, the rule of setting the display gray level and the field frequency multiple number of the LED circuit according to the set word command is as follows:

the lower 8 bits p [7:0] of the set word are the display gray levels:

when p [7:0] is equal to 1, 8 bits of gray scale are obtained;

when p [7:0] is equal to 2, it is 9 bits gray level;

when p 7:0 equals 3, it is 10 bits gray level;

11 bit gray levels when p [7:0] equals 4;

12 bit gray scale when p [7:0] equals 5;

when p [7:0] equals 6, it is 13 bits gray level;

when p [7:0] equals 7, it is 14 bits gray level;

when p [7:0] is equal to 8, it is 15 bits gray level;

when p [7:0] equals the other value, it is a 16-bit gray level.

Setting the word height 8 bits p [15:8] as the field frequency multiplier:

1 field frequency mode when p [15:8] equals 1;

2 times field frequency mode when p [15:8] is equal to 2;

a 3 times field frequency mode when p [15:8] is equal to 3;

4 times field frequency mode when p [15:8] equals 4;

5 times field frequency mode when p [15:8] equals 5;

6 times field frequency mode when p [15:8] equals 6;

7 times field frequency mode when p [15:8] equals 7;

8 times field frequency mode when p [15:8] equals 8;

9 times field frequency mode when p [15:8] equals 9;

the highest 10 times field frequency mode when p [15:8] is equal to the other values.

In addition, please refer to fig. 9, which is a circuit schematic diagram of the driving module provided by the present invention, the driving module is composed of 16 identical LED driving sub-circuits 31, that is, the 1 st driving circuit to the 16 th driving circuit in the figure, each LED driving sub-circuit 31 drives 1 LED/string, and 1 driving module can drive 16 LEDs/string at most.

When the driving module works, the driving module receives a field synchronization pulse Vsync sent by a front-end circuit, each Vsync pulse indicates the start of each field refresh, 16 driving sub-circuits share the Vsync pulse and a data word d [15:0], gate words s0 and s1 … s15 are respectively connected to a 1 st driving circuit and a 2 nd driving circuit … and a 16 th driving circuit, and when a gate word si of a data input port is high level, the data word d [15:0] is written into a first register in an i +1 th driving circuit.

Referring to fig. 10, the present invention further provides a circuit diagram of the driving sub-circuit. The driving sub-circuit 31 specifically includes a first register 311, a second register 312, a frequency doubling module 313, a PWM module 314, and an LED sub-circuit 315 formed by a single LED or a plurality of LEDs connected in series/in parallel.

When the corresponding bit si of the gate word input to the driving sub-circuit is high, the data word d [15:0] is written into the first register 311, when the Vsync pulse arrives, the first register 311 receives the Vsync pulse and dumps the data word d [15:0] stored in the first register 311 into the second register 312, and the second register 312 outputs the data word d [15:0] to the PWM module 314. At this time, the frequency doubling module 313 sets the corresponding field frequency doubling number and display gray level according to the setting word p [15:0], and the Vsync pulse generates a clock pulse of a higher frequency through the frequency doubling module 313. The PWM module 314 generates a PWM signal (PWM signal or PWM signal) according to the data word d [15:0] (adjusting the gray level of the current field) from the second register 312 under the driving of the frequency doubling pulse. When PWM is high, LED sub-circuit 315 is turned on and lit; conversely, when PWM is low, LED sub-circuit 315 is turned off and extinguished. Thus, the whole LED circuit can display the complete gray value only by one-time lighting refreshing.

In order to better represent the LED driving method and driving circuit provided by the present invention, in a specific embodiment, when the decoding command is a set word command, and the bit gray level of the LED circuit is set to 12 according to the set word command, and the field frequency multiple frequency is set to 1, the working waveform diagram of the PWM module is shown in fig. 11; in one embodiment, when the decoding command is a set word command, and the bit gray level of the LED circuit is set to 10 and the field frequency multiplication frequency is set to 2 according to the set word command, the operating waveform diagram of the PWM module is shown in fig. 12.

In summary, the present invention provides an LED driving method and a driving circuit, where the LED driving method includes the steps of: receiving data sent by a front-end circuit; decoding data sent by a front-end circuit and outputting a decoding command; carrying out corresponding parameter setting or driving operation on the LED circuit according to the decoding command; and receiving a synchronous pulse signal of the front-end circuit and driving the LED circuit to be turned on/off. The LED driving method provided by the invention enables the LED circuit to display without refreshing according to bits, only needs to transmit data once when displaying one field, and can realize multi-bit gray scale display through the rear-end LED driving circuit, thereby reducing data throughput and improving LED display efficiency; and even if the field frequency doubling technology is adopted, the data throughput is unchanged.

It should be understood that equivalents and modifications of the technical solution and inventive concept thereof may occur to those skilled in the art, and all such modifications and alterations should fall within the scope of the appended claims.

Claims

1. An LED driving method, comprising the steps of:

receiving data sent by a front-end circuit;

decoding data sent by a front-end circuit and outputting a decoding command;

the step of performing corresponding parameter setting or driving operation on the LED circuit according to the decoding command specifically includes:

when the output decoding command is a gating word command, controlling whether the part of the corresponding LED circuit is lighted or not according to the gating word command; when the output decoding command is a data word command, setting the gray value of the LED circuit according to the data word command;

when the output decoding command is a set word command, setting the display gray level and the field frequency multiplication number of the LED circuit according to the set word command;

receiving a synchronous pulse signal of a front-end circuit and driving an LED circuit to be turned on/off; when the corresponding bit of the input strobe word is at a high level, controlling the partial lightening of the corresponding LED circuit according to a strobe word command, setting the gray value of the LED circuit according to a data word command, and setting the display gray level and the field frequency multiplication frequency of the LED circuit according to a set word command;

when the corresponding bit of the gating word input into the driving circuit is high, a PWM signal is generated through the data word, when the PWM signal is high, the LED circuit is conducted and lightened, and when the PWM signal is low, the LED circuit is turned off and lightened.

2. The LED driving method according to claim 1, further comprising, after the step of receiving data transmitted from the front-end circuit, the steps of:

3. The LED driving method according to claim 2, wherein the step of decoding the data sent by the front-end circuit and outputting a decoding command specifically comprises:

selecting a command word and an identification code of the decoded data;

4. The LED driving method according to claim 3, wherein the step of selecting the command word and the identification code of the decoded data comprises:

forming the 1 st bit to the 16 th bit of the decoded data into a command word;

5. The LED driving method according to claim 4, wherein the step of determining the type of the command word and outputting the corresponding decoding command by the identification code of the decoded data includes:

when the identification code is equal to 00, the command word is ignored.

6. The LED driving method according to claim 1, wherein the step of setting the display gray scale level and the field frequency multiple number of the LED circuit according to the set word command when the outputted decoding command is the set word command specifically comprises:

7. An LED drive circuit, comprising an LED circuit composed of a plurality of LEDs, characterized by further comprising a drive circuit, the drive circuit comprising:

the driving module is used for receiving the decoding command output by the decoding module and performing driving operation; the driving module is also used for controlling whether the corresponding LED circuit part is lighted or not according to the gating word command when the output decoding command is the gating word command;

a setting module for receiving the decoding command output by the decoding module and setting parameters; the setting module is also used for setting the gray value of the LED circuit according to the data word command when the output decoding command is the data word command; when the output decoding command is a set word command, setting the display gray level and the field frequency multiplication number of the LED circuit according to the set word command;

when the corresponding bit of the input strobe word is at a high level, the driving module controls the part of the corresponding LED circuit to be lightened according to the strobe word command, the setting module sets the gray value of the LED circuit according to the data word command, and sets the display gray level and the field frequency multiplication frequency of the LED circuit according to the setting word command; when the corresponding bit of the gating word input into the driving circuit is high, a PWM signal is generated through the data word, when the PWM signal is high, the LED circuit is conducted and lightened, and when the PWM signal is low, the LED circuit is turned off and extinguished;

8. The LED driver circuit of claim 7, wherein the decoded commands comprise a strobe word command, a set word command, and a data word command.

9. The LED driving circuit according to claim 7, wherein the data interface module receives data sent by the front-end circuit by using an I2C interface or an SPI interface.