CN104582108A - Pulse width modulation (PWM) method for LED (light-emitting diode) drive integrated circuit - Google Patents
Pulse width modulation (PWM) method for LED (light-emitting diode) drive integrated circuit Download PDFInfo
- Publication number
- CN104582108A CN104582108A CN201310500460.6A CN201310500460A CN104582108A CN 104582108 A CN104582108 A CN 104582108A CN 201310500460 A CN201310500460 A CN 201310500460A CN 104582108 A CN104582108 A CN 104582108A
- Authority
- CN
- China
- Prior art keywords
- control signal
- brightness control
- led
- width modulation
- pulse
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Control Of El Displays (AREA)
Abstract
The invention discloses a pulse width modulation (PWM) method for an LED (light-emitting diode) drive integrated circuit. At least one comparator and a pulse counter are used in the method; the comparator compares a brightness control signal with an output value of the pulse counter with same digits as the brightness control signal, outputs the brightness control signal with a specific pulse width and controls a diode drive circuit through the brightness control signal, so that the external LED emits light of different brightness; output values of the pulse counter are arranged according to a certain rule, the on-off frequency of the diode in a fixed time period is increased, meanwhile, the utilization rate of the diode reaches 100%, and accordingly, the refresh rate is increased, and the loss of gray scale degrees is eliminated.
Description
Technical field
The present invention relates to a kind of pulse-width modulation method of LED drive integrated circult, particularly a kind of diode switch number of times that can pass through in raising light period, improve refresh rate, reduce LED scintillation, reduce the method for the LED drive integrated circult of GTG number of degrees loss.
Background technology
Along with the invention of RGB three kinds of monochromatic LEDs, LED is made to become possibility as the pixel of display screen.The series of advantages such as LED has low in energy consumption, and brightness is high, and the life-span is long, and antijamming capability is strong.Meanwhile, how to drive this type of screen display to go out word, static images, and dynamic video also become the emphasis of research.
Display Technique has two important parameters, and one is refresh rate, and two is grey exponent numbers.Refresh rate is higher, and the display of image is more stable, and scintillation is fewer, dynamic video to represent ability stronger.And the GTG number of degrees determine the number of the color kind that display can represent, the GTG number of degrees are higher, and the GTG number of degrees that can represent are more, thus the color that can represent is more, make picture more gorgeous, more true to nature.
But there is a factor mutually restricted between refresh rate and the GTG number of degrees, namely the high gray number of degrees constrain the realization of high refresh rate in certain degree.The GTG number of degrees are higher, need the light period more grown to show the light-emitting data of these high gray number of degrees; And refresh rate is higher, then need light period shorter.Thus the two forms contradiction in fluorescent lifetime problem.
For the mode of traditional PWM, if the GTG number of degrees improve, light period can be made elongated, cause refresh rate to decline; If it is constant to want to maintain refresh rate, need the less data output period in interval service time, this just causes the difficulty in driving chip design, adds cost.
For the type of drive of traditional OE time controling, the loss of the GTG number of degrees that the shortening that the raising of the GTG number of degrees brings the OE time equally causes or the decline of refresh rate.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of pulse-width modulation method improving the LED drive integrated circult of the refresh rate of LED, avoid the phenomenon that film flicker and the loss of the picture GTG number of degrees occur, solve high refresh rate with the above-mentioned contradiction between the high gray number of degrees, do not lose GTG, do not increase chip design difficulty prerequisite under improve refresh rate.
In order to solve above-mentioned technical problem, technical scheme of the present invention is: a kind of pulse-width modulation method of LED drive integrated circult, at least adopts a comparator and a pulse counter in the method; Wherein:
Described comparator, compared with the output numerical value of the pulse counter of a brightness control signal figure place identical with, export the brightness control signal of a certain pulses width, recycle this brightness control signal and control diode drive circuit, make external LED send the light of different brightness.
The output data of described pulse counter regularly arrange, and what increase the diode in the set time opens turn-off number of times, and diode utilance reaches 100% simultaneously.
The output data acquisition of described pulse counter arranges by the method for overall inverted order or part inverted order.
Described brightness control signal is according to normal sequence input comparator.
Described certain pulses width is modulated based on time pulse.
The binary numeral of n position, as arranged type (I), sorts by the sort method of described pulse counter numerical value:
A
m-1，A
m-2…A
0，A
m，A
m+1…A
n-1(I)
Wherein, n is positive integer, and m is the positive integer being less than or equal to n.
The ratio of the maximum binary numeral that the numerical value of brightness control signal is identical with its figure place is the duty ratio of brightness control signal within the pulse width modulation cycle, and namely this refer to the ratio of time that LED lights within pulse width modulation cycle pulse width modulation Cycle Length therewith.The size of duty ratio determines the power of luminosity, and being converted into brightness size is exactly the mean flow rate within the pulse width modulation cycle.The grade that the mean flow rate that the levels of precision of duty ratio then embodies LED can reach, be duty ratio accuracy higher, the number of degrees that mean flow rate can reach is more, and namely the GTG number of degrees are more.And namely the method obtaining the duty ratio of pinpoint accuracy is the figure place increasing brightness control signal.
The present invention maintains the size of duty ratio, make the approximate random distribution within the pulse width modulation cycle of the lighting time of LED simultaneously, improve the number of times of LED switch within the pulse width modulation cycle, define higher refresh rate, thus stopped the LED that conventional P WM method causes and light for a long time or extinguish the generation of the phenomenon causing film flicker when using camera or cameras capture picture.
Advantage of the present invention is:
(1) simplicity of design, only needs a comparator and a counter just can realize the present invention.For n road pio chip, comparator can multiplexing n time.Structure is simple, controls simple, reduces chip area, reduce costs.
(2) according to the requirement of specific environment for use, arranged type (I) can be used flexibly, for chip sets specific refresh rate, reach the scope of application widely.
(3) the GTG number of degrees are not lost.Make picture transition steady and smooth.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.
Fig. 1 is signal of the present invention circulation schematic diagram.
Fig. 2 is the chip digital part-structure schematic diagram of the type of drive of traditional OE time controling.
Fig. 3 is the chip structure figure of the PWM method adopting upgrading.
Fig. 4 is that the present invention compares with the simulation waveform of conventional P WM method.
Embodiment
The brightness change of LED is decided by the size of duty ratio, for the data that duty ratio is very little, lighting time is too short, fall time is very long, thus when using camera or video camera to catch picture, the phenomenon that in intercepted picture, some pixel is not lighted completely will occur, but be actually very little brightness.Thus make the picture intercepted produce scintillation.
The mode of lighting time approximate random has been dispersed in the pulse width modulation cycle by the present invention, makes the long fall time be become segment by large section, thus has stopped the generation of above-mentioned phenomenon, decreases the flicker of picture, improves the display quality of display.
The brightness control signal that the present invention produces maintains original duty ratio, so do not cause the loss of the GTG number of degrees, maintains the colorfulness of picture.
As Fig. 1, key of the present invention is pulse counter and comparator.
Fig. 2 is the chip digital part-structure sketch adopting traditional OE time drived control method, the realization of this control method also needs a control chip and OE signal generation chip to carry out the coding to OE signal according to the luma data of input, and realize the output of luma data, the cost so just increased and the complexity of control.In addition the utilance of the LED of this chip is relatively lower, causes the display of luma data incomplete.
Fig. 3 is that the refresh rate adopting the PWM method of upgrading to realize improves and do not lose the structure diagram of the numerical portion of the chip of the GTG number of degrees.The realization of this chip needs complicated controller.This chip can realize the output of data without the need to extra controller, as long as input brightness control signal.
The present invention, except having all advantages of Fig. 3 chip, only needs simple control unit, can realize the control to the method for the invention.The present invention status in figure 3 is just equivalent to counter, selector, comparator and the position residing for isochronous controller three, but it is simpler to realize principle.
As Fig. 1: original brightness control signal A, it is n bit binary value; The data B that counter produces is n bit binary value.Inverted order algorithm the low m-bit data in B is adopted positive sequential mode to put the high m position of n-bit data C into, and the backward of the n-m bit data that B is left, put into the low n-m position of C, thus obtain data C, compared with A, output pulse width modulating signal D.Following sortord (I) can be obtained thus:
C[n-1：0]＝{B
m-1，B
m-2…B
0，B
m，B
m+1…B
n1} (I)
Wherein, n is positive integer, and m is the positive integer being less than or equal to n.
The benefit of the method to export single pwm signal, also can realize the output of semirandom brightness data.Refresh rate can be improved greatly, and the GTG number of degrees can not be lost.
The continuous luminous time of some longer or the fluorescent lifetime distribution of approximate random can be obtained to the difference of m value within the pulse width modulation cycle: m value is larger, then the continuous luminous time produced is longer according to arranged type (I); M value is less, then the randomness of fluorescent lifetime is stronger.
As Fig. 4, be as n=8, A=(00001011)
2time, the contrast of m=6, m=1 and common PWM mode (m=8) simulation waveform.Can find out, different m can obtain different on-off times, and this decreases the continuous fall time for common PWM mode, thus has stopped the scintillation of LED, improves refresh rate; 0 to 2 have been expired because B gets
n-1 amounts to 2
nnumber, thus C also gets and has expired 0 to 2
n-1 amounts to 2
nnumber, is not only continuous print, this guarantees the GTG number of degrees and do not lose in order.Thus the present invention improves refresh rate under the situation not having the GTG number of degrees to lose.
The present invention achieves the high refresh rate under the high gray number of degrees by simple method, for LED display curtain provides a kind of new type of drive.Above-described embodiment does not limit the present invention in any way, and the technical scheme that the mode that every employing is equal to replacement or equivalent transformation obtains all drops in protection scope of the present invention.
Claims (3)
1. a pulse-width modulation method for LED drive integrated circult, is characterized in that at least adopting a comparator and a pulse counter in the method; Wherein:
Described comparator, compared with the output numerical value of the pulse counter of a brightness control signal figure place identical with, export the brightness control signal of a certain pulses width, recycle this brightness control signal and control diode drive circuit, make external LED send the light of different brightness;
The output data of described pulse counter regularly arrange, and increase the diode in the set time open turn-off number of times.
2. the pulse-width modulation method of LED drive integrated circult according to claim 1, is characterized in that: the overall inverted order of output data acquisition of described pulse counter or the method for part inverted order arrange.
3. the pulse-width modulation method of LED drive integrated circult according to claim 1, is characterized in that: described brightness control signal is according to normal sequence input comparator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310500460.6A CN104582108A (en) | 2013-10-22 | 2013-10-22 | Pulse width modulation (PWM) method for LED (light-emitting diode) drive integrated circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310500460.6A CN104582108A (en) | 2013-10-22 | 2013-10-22 | Pulse width modulation (PWM) method for LED (light-emitting diode) drive integrated circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104582108A true CN104582108A (en) | 2015-04-29 |
Family
ID=53097027
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310500460.6A Pending CN104582108A (en) | 2013-10-22 | 2013-10-22 | Pulse width modulation (PWM) method for LED (light-emitting diode) drive integrated circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104582108A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106102252A (en) * | 2016-07-29 | 2016-11-09 | 杭州芯讯科技有限公司 | LED light-dimming method and light modulating device |
| CN111445839A (en) * | 2020-04-17 | 2020-07-24 | 广州视源电子科技股份有限公司 | L ED display screen driving method, device, system, equipment and storage medium |
-
2013
- 2013-10-22 CN CN201310500460.6A patent/CN104582108A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106102252A (en) * | 2016-07-29 | 2016-11-09 | 杭州芯讯科技有限公司 | LED light-dimming method and light modulating device |
| CN106102252B (en) * | 2016-07-29 | 2018-06-26 | 杭州芯讯科技有限公司 | LED light-dimming methods and light modulating device |
| CN111445839A (en) * | 2020-04-17 | 2020-07-24 | 广州视源电子科技股份有限公司 | L ED display screen driving method, device, system, equipment and storage medium |
| CN111445839B (en) * | 2020-04-17 | 2021-12-14 | 广州视源电子科技股份有限公司 | Driving method, device, system, equipment and storage medium of LED display screen |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107205293B (en) | Light emitting diode driving circuit and method | |
| KR100778487B1 (en) | Modulation circuit, image display using the same, and modulation method | |
| CN102054434B (en) | Light-emitting diode (LED) display system and method having pulse scattering mode | |
| US20210020101A1 (en) | Driver for led display | |
| CN109147653A (en) | A kind of LED drive chip display control OS-PWM method | |
| US20110127922A1 (en) | llumination device comprising multiple LEDs | |
| CN102157130A (en) | Pulse width modulating method for LED driving integrated circuit | |
| KR102289459B1 (en) | Backlight unit, display apparatus having the same and operating method of backlight unit | |
| CN103000123A (en) | Pulse width regulating device | |
| Lv et al. | Energy-saving driver design for full-color large-area LED display panel systems | |
| CN103165075B (en) | Driving circuit of light emitting diode and method thereof | |
| CN102006696B (en) | Light-emitting diode backlight drive circuit, method and constant current source thereof | |
| CN108630138A (en) | Gray scale generation circuit and driving circuit using the same | |
| CN102411897A (en) | LED display system having pulse scattering mode and method thereof | |
| TWI488164B (en) | Led driver circuit, driver system and driving method thereof | |
| CN103813579B (en) | Light emitting diode driving circuit and driving system of light emitting diode | |
| CN104123913A (en) | LED (Light-Emitting Diode) scanning method | |
| CN104582108A (en) | Pulse width modulation (PWM) method for LED (light-emitting diode) drive integrated circuit | |
| CN103347337A (en) | Pulse width modulation method of LED driving integrated circuit | |
| US9099044B2 (en) | Apparatus and method for driving light emitting diode | |
| CN116229889A (en) | Non-uniform pulse width gray scale modulation method and device for non-electrical contact type QLED display | |
| TW201442554A (en) | LED driver | |
| CN113436574A (en) | LED driving chip algorithm for optimizing low-gray display effect | |
| TWM452576U (en) | LED driver circuit and driver system | |
| TWI609602B (en) | Multi-channel light emitting diode drive control device and system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20150429 |