CN1484213A - Method and device for controlling luminance of large LED screen - Google Patents
Method and device for controlling luminance of large LED screen Download PDFInfo
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- CN1484213A CN1484213A CNA021309221A CN02130922A CN1484213A CN 1484213 A CN1484213 A CN 1484213A CN A021309221 A CNA021309221 A CN A021309221A CN 02130922 A CN02130922 A CN 02130922A CN 1484213 A CN1484213 A CN 1484213A
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Abstract
The invention is kind of large-screen luminous diode brightness control method, includes selecting luminous diode, current supplies time-shared with PWM control mode, scans according to the input signal; the large-screen works with divided modules, the picture signal is transmitted to each module through data interface, the PWM signal generator on the module turns the picture signal into PWM signal, supplies the diode with scanning type through driving circuit; the two ends of diode D are connected with capacitance C; one ends connects with fly-wheel diode Dx, and a energy storing induction L is connected between the Dx and the other end. The control device includes module data interface circuit and PWM signal generator, driving circuit and luminous diode matrix; especially the two ends of luminous diode in the matrix connect with capacitance C; one end connects with fly-wheel diode Dx, a energy storing induction L is connected between the Dx and the other end.
Description
Technical field
The present invention relates to light emitting diode is the LED Large Screen Display Technology, and particularly high-level efficiency is utilized electric energy, overcome the display control technology that single LED manages the brightness dispersiveness, has reduced the screening requirement of large screen display to the LED pipe.
Background technology
With LED is the big screen display screen of pixel, and the brightness of each LEDs all needs to be subjected to the control of circuit system and demonstrates required image.The method of control LED brightness mainly contains at present:
Electric current control method, the electric current that flows through among the LED by change changes brightness.Each pixel all needs a controllable current source in this method, and its shortcoming is the circuit complexity, the cost height.
PWM is the width modulation method, it is to change the luminous time of LED by dutycycle, and utilizes the persistence of vision of human eye, changes brightness.This also is present the most frequently used method.General LED maximum current under the situation of direct drive is 20mA, and is that 1/10 o'clock peak inrush current is 100mA in dutycycle, half when its mean value has only direct current supply, so brightness half when also having only direct current supply.And brightness LED display exactly, the important performance indexes of especially outdoor screen, so there is the such shortcoming of luminance shortage in the PWM type of drive, and the luminous utilization factor of LED is not high, and brightness is subjected to certain limitation.
Also have, more than two kinds of methods also have a common shortcoming, be exactly that power utilization efficient is low.Because the forward voltage drop Vf of LED has certain discreteness, in order to make the brightness unanimity of each pixel, must add current-limiting resistance on the circuit or leave certain pressure drop as the electric current adjustment.Current-limiting resistance and electric current adjustment all will consume certain power with control IC, and the power of consumption has not only been wasted the energy, and the temperature of circuit is risen, and influence reliability.
In addition, the adjustment of brightness needs pointwise to adjust the part parameter in the prior art, very inconvenience.
Summary of the invention
In order to overcome above-mentioned the deficiencies in the prior art part, the present invention proposes LED energy storage driving and be the large LED screen brightness control method of core, control the brightness that the power that is added on the LED strengthens LED by energy-storage travelling wave tube, and employing storage computation formula pixel brightness correction method, thereby solved the circuit complexity in the classic method, brightness is limited and efficiency is low, poor reliability, and the problem of inconvenience is adjusted in brightness, the effect that the LED that can use the lower LED of price to reach the costliness that must use in the classic method just can reach, thereby improved control performance, reduced cost.
Purpose of the present invention can reach like this:
Design, a kind of large LED screen brightness control method of employing comprise the screening light emitting diode, by the clock cycle large LED screen are carried out time sharing power supply, and according to the input signal method for scanning; The collaborative work of described giant-screen sub-module, picture signal transmits to each module through data-interface, and the PWM generator on the module converts picture signal to pwm signal, powers to light emitting diode in the mode of scanning by driving circuit; It is characterized in that, at the light emitting diode D two ends of described giant-screen and connect capacitor C; Termination at described light emitting diode D is gone into sustained diode x, and inserts energy storage inductor L between the other end of this light emitting diode D and sustained diode x.
Design, a kind of large LED screen brightness controlling device of manufacturing comprise module data interface circuit and the pwm signal generator that is attached thereto, and driving circuit and dot matrix LEDs; It is characterized in that the two ends of the light emitting diode D in the described matrix also are connected to capacitor C; The one end also is connected to sustained diode x, and is connected to energy storage inductor L between its other end and described sustained diode x.
Description of drawings:
Fig. 1 is the LED unit basic block diagram of additional L, C energy storage driving element;
Fig. 2 is the another kind of structural drawing in described energy storage drive-type LED unit;
Fig. 3 is the general structure synoptic diagram of large LED screen brightness control method of the present invention and device;
Fig. 4 is the johning knot composition of described energy storage drive-type LED unit serial connection double pole triode;
Fig. 5 is the johning knot composition of described energy storage drive-type LED unit serial connection fet.
Embodiment
Below in conjunction with accompanying drawing in detail embodiments of the invention are described in detail.
A kind of large LED screen brightness control method comprises the screening light emitting diode, by large LED screen being carried out time sharing power supply by the clock cycle, and according to the input signal method for scanning; The collaborative work of described giant-screen sub-module, picture signal transmits to each module through data-interface, and the PWM generator on the module converts picture signal to pwm signal, powers to light emitting diode in the mode of scanning by driving circuit; It is characterized in that: at the light emitting diode D two ends of described giant-screen and connect the capacitor C of suitable appearance value; Termination at described light emitting diode D is gone into sustained diode x, and inserts the energy storage inductor L of suitable inductance value between the other end of this light emitting diode D and sustained diode x.
On described module, establish the data operation unit; Described picture signal is sent to PWM generator again behind data-interface input data operation unitary operation;
Other establishes storer, stores the luminance difference value or the modified value of each pixel on the described module; This luminance difference value or modified value are sent into described data operation unit compensate computing.
The anode of described light emitting diode D or negative terminal can insert controlled triode; The control utmost point of this triode connects the pwm signal of driving circuit.Usually, the light emitting diode of each module can be divided into many groups, and every group by a triode driving.
In a kind of embodiment, described controlled triode is bipolar semiconductor pipe TR1; Light emitting diode D is serially connected in its collector loop or the emitter circuit.
In the another kind of embodiment, described controlled triode is fet TR2, and light emitting diode D is serially connected in its source electrode or the drain electrode loop.
A kind of large LED screen brightness controlling device comprises module data interface circuit 2 and the pwm signal generator 1 that is attached thereto, and the driving circuit 5 and the dot matrix LEDs 6 that link to each other successively; It is characterized in that: the two ends of the light emitting diode D in the described matrix also are connected to the capacitor C of suitable appearance value; The one end also is connected to sustained diode x, and is connected to the energy storage inductor L of suitable inductance value between its other end and described sustained diode x.
Between described module data interface circuit 2 and the PWM generator 1, also be provided with module data arithmetic element 3; Described module data arithmetic element 3 also with have this module pixel point brightness difference value or modified value and storer 4 link to each other.
The anode of described light emitting diode D or negative terminal can connect controlled triode; The control utmost point of this triode connects pwm signal.Usually, the light emitting diode of each module can be divided into many groups, and every group by a triode driving.
In one embodiment, described controlled triode adopts bipolar semiconductor pipe TR1; Described light emitting diode D is serially connected in its collector loop or the emitter circuit.
In another kind of embodiment, described controlled triode adopts fet TR2, and described light emitting diode D is serially connected in its source electrode or the drain electrode loop.
The basic circuit of this energy storage drive-type scheme is seen Fig. 1, Fig. 2.Power supply, charges and energy storage in L to C to light emitting diode D power supply simultaneously by inductance L when switch closure promptly has input pulse; Energy when the switch disconnection promptly is input as zero among the L continues the power supply to D by Dx, charges to C simultaneously; When the electric energy that stores among the L exhausted, the electric energy that is full of among the C can continue the power supply to D, begins up to next cycle.The power that obtains on the light emitting diode D depends on the length of switch closure time in each cycle, i.e. the dutycycle of switch closure.As long as the enough big light-emitting diodes D of the capacity two ends of C are similar to direct current supply basically, avoided common PWM to drive the limited problem of brightness that method is brought owing to moment is luminous.Because the power that LED obtains depends primarily on the inductance value of supply voltage and L, and the dutycycle of switch, less with the forward voltage drop relation of LED, therefore omitted current-limiting resistance, improved efficient.
Described energy storage drive-type basic circuit can be realized by several physical circuits among Fig. 4, Fig. 5.Wherein, the energy storage drive-type light emitting diode of Fig. 4-1,4-2 is connected in the transistor collector loop, and the energy storage drive-type light emitting diode of Fig. 4-3,4-4 is connected in the transistor emitter loop; And the energy storage inductor L of Fig. 4-1,4-3 is connected on the anode of light emitting diode D, and the energy storage inductor L of Fig. 4-2,4-4 is connected on the negative electrode of light emitting diode D.Controlled triode adopts fet among Fig. 5, and is similar among connection and Fig. 4.
In LED giant-screen implementation, if the parameter discrete of the energy storage inductor of each pixel, electric capacity, or the luminescence efficiency of LED itself there are differences, and can make that to occur brightness on the screen between the different pixels inconsistent, can show as defectives such as color spot, a white consistance be bad on visual effect.At this problem, can adopt storage computation formula pixel brightness correction method to solve.
The structure of general LED jumbotron display screen is at first to add driving circuit by tens to several thousand LED to form module, dresses up the monoblock display screen by module spliced again.Module generally is to finish assembling, aging, test in factory, and assembly unit is to finish at the scene.
Storage computation formula pixel brightness correction method is to add a storer 4 on each module, can adopt PROM, EPROM, EEPROM, FLASH MEMORY etc., data or its modified value in order to the luminance difference that writes down each pixel, the data of record are carried out computing with the brightness data that will show in module data arithmetic element 3, the luminance difference of compensation pixel, driving LED obtains more satisfactory display effect then.
In the process that module is produced, gather luminance difference data or modified value by test, deposit in the storer.The module that is finished product promptly is the module that compensated, and directly assembly unit can reach good effect.Particularly through after a while use, some pixel occurs aging, and brightness changes, equally can be by storage computation formula pixel brightness correction method, on-the-spot data in the storer are upgraded, and make the brightness of each pixel reach consistent, and improve effect.
Evidence, employing energy storage type driving method substantially can be not influential to the response time, can not produce to lag behind and conditions of streaking yet.
Adopt the energy storage type driving method in theory, because traditional type of drive is compared in the effect of L, C element, the response time is can be slow, but in the middle of the practical application of LED jumbotron display screen, the prolongation of this response time can not impact for display effect.
We know that the retentivity time of eye of human eye generally is about 15 milliseconds.Will feel if the response time of a display device surpasses the 15mS human eye,, when showing dynamic image, will obviously feel conditions of streaking if the response time surpasses 25mS.In the LCD display device because the restriction of liquid crystal display itself, the response time mostly more than 25mS, have in addition more than 40mS, so people can see tangible hangover when watching dynamic image with LCD.And the display device CRT monitor of previous generation since the response time below 10mS, just do not have conditions of streaking.
The response time of display device is that the response time of LED itself does not have problems in μ S level by the decision of response time of the response time of luminophor and driving circuit; Because it is the turntable driving of LED jumbotron display screen is finished in each module, and the pixel quantity of each module drive is limited, therefore very high to the refreshing frequency of each picture element scan.Module with 8 * 8 dot matrix is an example: we adopt 8 row parallel-by-bit method for scanning to drive, and the Dot Clock of supposing PWM is 100MHz, adopt the color depth of R, G, the every look 10Bit of B, and then every row PWM cycle is:
1024/100×10
6＝10.24μS
The scan period of each module is the about 82 μ S of 8 * 10.24 μ S, that is to say, can accomplish 82 μ S with the LED display response time that traditional PWM driving method drives.After adopting the energy storage type driving method, in order to make the electric current that obtains on the LED more steady, we are set to 10 times of scan period with the time constant of energy-storage travelling wave tube, and we still can obtain the response time of 820 μ S so.If we adopt the module of 8 * 16 or 16 * 16 dot matrix, the response time still can be accomplished 1.64mS.
Therefore adopt the energy storage type driving method and cause the small prolongation of response time, can not impact display effect.
As previously mentioned, behind employing the present invention, first: the brightness of the existing LED display that adopts the PWM driving method is improved, improve viewing effect.Second: can use the LED that hangs down one-level to reach the effect of senior LED, save cost.The the 3rd: can improve the power supply service efficiency of display screen, save the energy.The the 4th: reduce thermal value, improve reliability and serviceable life.The 5th: the brightness adjustment particularly uses the brightness adjustment after a period of time very convenient, can avoid pointwise to adjust element, thereby improves effect.
Claims (10)
1, a kind of large LED screen brightness control method comprises the screening light emitting diode, by the clock cycle large LED screen is carried out time sharing power supply, and according to the input signal method for scanning; The collaborative work of described giant-screen sub-module, picture signal transmits to each module through data-interface, and the PWM generator on the module converts picture signal to pwm signal, powers to light emitting diode in the mode of scanning by driving circuit; It is characterized in that:
At the light emitting diode D two ends of described giant-screen and connect capacitor C; Termination at described light emitting diode D is gone into sustained diode x, and inserts energy storage inductor L between the other end of this light emitting diode D and sustained diode x.
2, according to the described control method of claim 1, it is characterized in that:
On described module, establish the data operation unit; Described control signal is sent to the generation pwm signal again behind the data operation unitary operation;
Other establishes storer, stores the luminance difference value or the modified value of each pixel on the described module; This luminance difference value or modified value are sent into described data operation unit compensate computing.
3, according to claim 1 or 2 described control methods, it is characterized in that:
The anode of described light emitting diode D or negative terminal insert controlled triode; The control utmost point of this triode connects the pwm signal of driving circuit.
4, according to the described control method of claim 3, it is characterized in that:
Described controlled triode is bipolar semiconductor pipe TR1; Light emitting diode D is serially connected in its collector loop or the emitter circuit.
5, control method according to claim 3 is characterized in that:
Described controlled triode is fet TR2, and light emitting diode D is serially connected in its source electrode or the drain electrode loop.
6, a kind of large LED screen brightness controlling device, the pwm signal generator (1) that comprises module data interface circuit (2) and be attached thereto, and the driving circuit (5) and the dot matrix LEDs (6) that link to each other successively; It is characterized in that:
The two ends of light emitting diode D in the described matrix also are connected to capacitor C; The one end also is connected to sustained diode x, and is connected to energy storage inductor L between its other end and described sustained diode x.
7, device according to claim 6 is characterized in that:
Between described module data interface circuit (2) and the pwm signal generator (1), also be provided with data operation unit (3); Described data operation unit (3) also links to each other with the storer that has this module pixel point brightness difference value or modified value and appropriate address (4).
8, according to claim 6 or 7 described devices, it is characterized in that:
The anode of described light emitting diode or negative terminal connect controlled triode; The control utmost point of this triode connects pwm signal.
9, device according to claim 8 is characterized in that:
Described controlled triode is bipolar semiconductor pipe TR1; Described light emitting diode D is serially connected in its collector loop or the emitter circuit.
10, device according to claim 8 is characterized in that:
Described controlled triode is fet TR2, and described light emitting diode D is serially connected in its source electrode or the drain electrode loop.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA021309221A CN1484213A (en) | 2002-09-17 | 2002-09-17 | Method and device for controlling luminance of large LED screen |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA021309221A CN1484213A (en) | 2002-09-17 | 2002-09-17 | Method and device for controlling luminance of large LED screen |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007107611A1 (en) * | 2006-03-22 | 2007-09-27 | Jaime Perez Boils | Led luminous-panel modular system |
| US7394444B2 (en) | 2005-02-15 | 2008-07-01 | Samsung Electronics Co., Ltd. | LED driver |
| CN100464614C (en) * | 2006-02-23 | 2009-02-25 | 盛群半导体股份有限公司 | Structure and method for improving LED grey scale display performance |
| CN101080865B (en) * | 2004-12-16 | 2010-06-09 | 康弗蒂姆英国有限公司 | Matrix converter |
| CN104184924A (en) * | 2014-09-05 | 2014-12-03 | 大连集思特科技有限公司 | Displaying method for LED smart glass |
| CN114420060A (en) * | 2022-01-20 | 2022-04-29 | 上海龙旗科技股份有限公司 | MiniLED backlight display device and method |
-
2002
- 2002-09-17 CN CNA021309221A patent/CN1484213A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101080865B (en) * | 2004-12-16 | 2010-06-09 | 康弗蒂姆英国有限公司 | Matrix converter |
| US7394444B2 (en) | 2005-02-15 | 2008-07-01 | Samsung Electronics Co., Ltd. | LED driver |
| CN100464614C (en) * | 2006-02-23 | 2009-02-25 | 盛群半导体股份有限公司 | Structure and method for improving LED grey scale display performance |
| WO2007107611A1 (en) * | 2006-03-22 | 2007-09-27 | Jaime Perez Boils | Led luminous-panel modular system |
| ES2286935A1 (en) * | 2006-03-22 | 2007-12-01 | Jaime Perez Boils | Led luminous-panel modular system |
| CN104184924A (en) * | 2014-09-05 | 2014-12-03 | 大连集思特科技有限公司 | Displaying method for LED smart glass |
| CN104184924B (en) * | 2014-09-05 | 2018-01-30 | 大连集思特科技有限公司 | The display methods of LED intelligent glass |
| CN114420060A (en) * | 2022-01-20 | 2022-04-29 | 上海龙旗科技股份有限公司 | MiniLED backlight display device and method |
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