CN101872588A - Uniform brightness constant current LED drive device and method based on embedded system - Google Patents
Uniform brightness constant current LED drive device and method based on embedded system Download PDFInfo
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- CN101872588A CN101872588A CN201010175758A CN201010175758A CN101872588A CN 101872588 A CN101872588 A CN 101872588A CN 201010175758 A CN201010175758 A CN 201010175758A CN 201010175758 A CN201010175758 A CN 201010175758A CN 101872588 A CN101872588 A CN 101872588A
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Abstract
The invention discloses uniform brightness constant current LED drive device and method based on an embedded system. The device comprises an embedded module, a square wave generation circuit and a constant current source drive output module, wherein the output end of the square wave generation circuit is connected with the input end of the embedded module; and the output end of the embedded module is connected with the input end of the constant current source drive output module. The method comprises the steps of: converting a control signal output by an LED control device into a proportion function signal by an exponential function conversion module; multiplying the proportion function signal by the number of minimum pulse width time, and then converting into a pulse duration modulation signal by a roundoff module; processing the pulse duration modulation signal by the constant current source drive output module to obtain drive current which is the current corresponding to brightness specified by the control signal. The invention has the advantages of simple structure and accurate control.
Description
Technical field
The present invention relates to a kind of uniform brightness constant current LED drive device and method based on embedded system.
Background technology
Along with the development of LED display technique, the application of constant-current LED chip for driving more and more widely.LED constant-current driven chip in the market all adopts constant current+uniform current to change and realizes, promptly when carrying out drive current control, the variation of each rank electric current is uniform.When reality was used, under the little current conditions, each rank electric current changes can both make the LED light-emitting diode luminance change; Under the big current conditions, each rank electric current changes then corresponding LED light-emitting diode luminance and changes very little and even imperceptible.
In order to realize the even variation of LED brightness, need the extra peripheral circuit that increases, increased the cost of entire circuit greatly.
Summary of the invention
The purpose of this product invention is to optimize the system schema that LED display drives, and realizes LED light-emitting diode luminance even variation, reduces extra peripheral circuit, reduces the realization cost of system.
The present invention adopts following technical scheme for achieving the above object:
The present invention is based on the uniform brightness constant current LED drive device of embedded system, comprise that flush bonding module, square wave generation circuit and constant current source drive output module, the input end of the output termination flush bonding module of square wave generation circuit, the output termination constant current source of flush bonding module drives the input end of output module.
Preferably, described flush bonding module comprises exponential function modular converter and rounding block, the output terminal of the input termination square wave generation circuit of exponential function modular converter wherein, the input end of the output termination rounding block of exponential function modular converter, the output termination constant current source of rounding block drives the input end of output module.
Driving method based on the uniform brightness constant current LED drive device of embedded system is as follows:
The control signal of LED control device output converts the proportion function signal to by the exponential function modular converter, to pass through rounding block after the number of described proportion function signal times with the minimum pulse width time, convert pulse-width signal to, through the constant-current driving output module, obtaining drive current is exactly the pairing electric current of control signal given luminance with described pulse-width signal.
The present invention programmes by embedded software, and exponential function is cured to chip internal, after external control signal transforms by program curing, make each jump value difference of drive current, promptly under little current status, each rank electric current difference is little, under the current state, each rank electric current difference is big.The controlling and driving output current is realized LED light-emitting diode luminance even variation, in the full color unit of forming with RGB three-color LED light emitting diode, makes color transition soft.
Description of drawings
Fig. 1: structural drawing of the present invention.
Embodiment
Be elaborated below in conjunction with the technical scheme of accompanying drawing to invention:
As shown in Figure 1, be uniform brightness constant current LED chip for driving structural representation.The embedded software of module in the frame of broken lines for solidifying is used for converting input control signal to corresponding PWM pulse width signal, control constant current output module.
In the synoptic diagram, the square-wave signal that square-wave generator produces mainly has influence on minimum pulse width signal and refreshing frequency.
Embodiment is as follows:
Square-wave generator produces the square wave of 2MHz, and the minimum pulse width Design of Signal is 0.5 microsecond, and refreshing frequency is decided to be 2KHz.1000 minimum pulse width times are then arranged in each refresh cycle.The LED light-emitting diode luminance is defined as 256 rank (being that output driving current is divided into 256 rank).
High-high brightness is defined as 1000 minimum pulse widths, and minimum brightness is defined as 1 minimum pulse width, and 0 pulsewidth is a close current.
Control signal is by the exponential function converse routine, and the result of generation converts proportion function to, multiply by 1000, by the program of rounding off, converts the pulsewidth unit of integer to.Remove to control the constant-current driving output module by this pulse width signal, the electric current that obtains is exactly the pairing electric current of control signal given luminance.Control signal is incremented to 256 from 1, just can see that the uniform brightness of LED light emitting diode that drive output connects changes.
Unit is in the refresh cycle, and the minimum pulse width time is many more, and the drive current degree of verisimilitude of controlling by the pwm signal of embedded software conversion is high more; But after minimum pulse width narrowed down, the precision that little electric current drives output current down can be short of to some extent.
Refreshing frequency is low more, and the minimum pulse width quantity in the unit period is high more, and the drive current variations degree of verisimilitude is high more, but refreshing frequency is low excessively, can cause harmful effect to total system.
Claims (3)
1. uniform brightness constant current LED drive device based on embedded system, it is characterized in that comprising that flush bonding module, square wave generation circuit and constant current source drive output module, the input end of the output termination flush bonding module of square wave generation circuit, the output termination constant current source of flush bonding module drives the input end of output module.
2. the uniform brightness constant current LED drive device based on embedded system according to claim 1, it is characterized in that described flush bonding module comprises exponential function modular converter and rounding block, the output terminal of the input termination square wave generation circuit of exponential function modular converter wherein, the input end of the output termination rounding block of exponential function modular converter, the output termination constant current source of rounding block drives the input end of output module.
3. driving method based on the uniform brightness constant current LED drive device of embedded system is characterized in that described method is as follows:
The control signal of LED control device output converts the proportion function signal to by the exponential function modular converter, to pass through rounding block after the number of described proportion function signal times with the minimum pulse width time, convert pulse-width signal to, through the constant-current driving output module, obtaining drive current is exactly the pairing electric current of control signal given luminance with described pulse-width signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201010175758A CN101872588A (en) | 2010-05-18 | 2010-05-18 | Uniform brightness constant current LED drive device and method based on embedded system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201010175758A CN101872588A (en) | 2010-05-18 | 2010-05-18 | Uniform brightness constant current LED drive device and method based on embedded system |
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| CN101872588A true CN101872588A (en) | 2010-10-27 |
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| CN201010175758A Pending CN101872588A (en) | 2010-05-18 | 2010-05-18 | Uniform brightness constant current LED drive device and method based on embedded system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103974499A (en) * | 2013-02-01 | 2014-08-06 | 立锜科技股份有限公司 | Linear dimming circuit and method for light emitting component |
| CN104661386A (en) * | 2013-11-25 | 2015-05-27 | 上海航空电器有限公司 | Exponential dimming circuit with temperature compensation function |
| CN106448578A (en) * | 2016-12-22 | 2017-02-22 | 广东欧珀移动通信有限公司 | Display screen back light control method, display screen back light control device and computer equipment |
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| CN2678303Y (en) * | 2003-12-26 | 2005-02-09 | 北京映像天视科技有限公司 | LED lighting circuit |
| CN101511142A (en) * | 2009-03-09 | 2009-08-19 | 华南理工大学 | Switch constant-current source circuit without feedback on load end |
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2010
- 2010-05-18 CN CN201010175758A patent/CN101872588A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2678303Y (en) * | 2003-12-26 | 2005-02-09 | 北京映像天视科技有限公司 | LED lighting circuit |
| CN101511142A (en) * | 2009-03-09 | 2009-08-19 | 华南理工大学 | Switch constant-current source circuit without feedback on load end |
Non-Patent Citations (1)
| Title |
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| 《国外电子元器件》 20050731 廖建兴 双输出升压型转换器LT3466 全文 1-3 , 第7期 2 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103974499A (en) * | 2013-02-01 | 2014-08-06 | 立锜科技股份有限公司 | Linear dimming circuit and method for light emitting component |
| CN104661386A (en) * | 2013-11-25 | 2015-05-27 | 上海航空电器有限公司 | Exponential dimming circuit with temperature compensation function |
| CN106448578A (en) * | 2016-12-22 | 2017-02-22 | 广东欧珀移动通信有限公司 | Display screen back light control method, display screen back light control device and computer equipment |
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Open date: 20101027 |