CN101719345B

CN101719345B - LED display system and control method thereof as well as driver of LED display system and control method thereof

Info

Publication number: CN101719345B
Application number: CN2008101696791A
Authority: CN
Inventors: 林水木; 刘玓玓; 杨奂箴
Original assignee: Richtek Technology Corp
Current assignee: Richtek Technology Corp
Priority date: 2008-10-09
Filing date: 2008-10-09
Publication date: 2012-12-05
Anticipated expiration: 2028-10-09
Also published as: CN101719345A

Abstract

The invention relates to an LED display system and a control method thereof, as well as a driver of the LED display system and a control method thereof. The LED display system comprises a plurality of LEDs, a plurality of drivers and a power converter and is characterized in that the LEDs are arranged in the display system; the drivers are used for driving the multiple LEDs, each driver is provided with a plurality of LED pins which are respectively in an electric connection with one of the LEDs, and each driver outputs a feedback signal at a feedback signal node; and the power converter is arranged in the display system and used for receiving a direct current high voltage and converting the direct current high voltage into at least a direct current low voltage to the LEDs, and the power converter adjusts the at least one direct low voltage according to one of a plurality of feedback signals.

Description

The driver of LED display system and control method thereof and this system and control method

Technical field

The present invention relates to a kind of LED display system, specifically, is a kind of dynamical LED display system.

Background technology

Fig. 1 shows conventional use in the LED of billboard display system 100, comprises that one exchanges a direct current transducer 102 and a display panel 104, wherein exchange to direct current transducer 102 5V is provided power supply to display panel 104.Display panel 104 comprises led light source 106,110 and 114 and driver 108,112 and 116 driving LED light sources 106,110 and 114 respectively; Each led light source 106 comprises a plurality of LED118; Each led light source 110 comprises a plurality of LED120; Each led light source 114 comprises a plurality of LED122, and LED118 and 120 forward bias voltage drop are about 2.2V, the about 3.6V of the forward bias voltage drop of LED122; And exchange the voltage that direct current transducer 102 is provided is 5V; Therefore make LED118,120 and 122 overheated and damage for fear of unnecessary voltage, each LED118,120 and 122 each connect with a resistance R c, resistance R c as heat absorber (heat sinker) to share the heat on the LED118,120 and 122.

Yet; Between exchanging, segment distance is arranged, therefore will consume many power to power lead between direct current transducer 102 and the display panel 104 and online line resistance Rp and the Rg of ground connection, in addition in interchange to direct current transducer 102 and display panel 104; Though resistance R c can share the heat on the LED118,120 and 122; But also cause power consumption, in other words, resistance R p, Rg and Rc will make the usefulness of LED display system 100 descend.

Therefore known LED display system exists above-mentioned all inconvenience and problem.

Summary of the invention

The object of the invention is to propose a kind of dynamical LED display system and control method thereof.

Another object of the present invention is to propose a kind of driver and control method thereof of LED display system.

For realizing above-mentioned purpose, technical solution of the present invention is:

A kind of LED display system comprises a plurality of LED, and a plurality of drivers and a power supply changeover device is characterized in that:

Said a plurality of LED is arranged in the said display system;

Said a plurality of driver; In order to drive said a plurality of LED; Each said driver has a plurality of LED pins, and said a plurality of LED pins are electrically connected one of them of said a plurality of LED separately, and each said driver is exported a feedback signal in a feedback signal node place;

Said power supply changeover device; Be arranged in the said display system; In order to receive DC high voltage; And convert said high direct voltage at least one dc low-voltage and give said a plurality of LED, said power supply changeover device has a back coupling pin and connects said a plurality of feedback signal node, and regulates said at least one dc low-voltage according to one of said a plurality of feedback signals.

LED display system of the present invention can also adopt following technical measures further to realize.

Aforesaid LED display system comprises more that wherein a second source converter transfers alternating voltage to said high direct voltage.

Aforesaid LED display system, wherein said power supply changeover device receives said high direct voltage, and converts said high direct voltage into two kinds of dc low-voltages, is supplied to different LED respectively.

Aforesaid LED display system, wherein each said driver more comprises:

One minimum voltage Chooser is by choosing minimum value in the voltage on said a plurality of LED pins;

One gain circuitry produces said feedback signal according to said minimum value.

Aforesaid LED display system, wherein said gain circuitry comprises a compensating circuit, the error that produces to compensate said feedback signal Yin Wendu.

Aforesaid LED display system, wherein said gain circuitry comprises a controller, to control the gain of said gain circuitry.

Aforesaid LED display system, wherein said each driver more comprise the electric current of the said a plurality of LED of each Self Control of a plurality of current sources on one of them.

Aforesaid LED display system, wherein said a plurality of current sources comprise separately:

One resistance;

One transistor is connected between one of them and the said resistance of said a plurality of LED pins;

One operational amplifier has one first input connection, one voltage end, one second input connection one node and the output between said resistance and transistor and connects said transistorized gate.

Aforesaid LED display system, wherein each said driver more comprises:

One maximum voltage Chooser is chosen maximal value in the transistorized gate voltage by said a plurality of current sources;

One gain circuitry produces said feedback signal according to said maximal value.

Aforesaid LED display system, wherein each said driver more comprises:

One gain circuitry produces a direct current signal according to said minimum value;

One current source is in order to provide an electric current to said feedback signal node;

One switch is connected between a said feedback signal node and the earth terminal;

One change-over circuit produces a PWM signal according to the voltage on said direct current signal and the said feedback signal node and switches said switch to regulate said feedback signal.

Aforesaid LED display system, wherein said gain circuitry comprises the error that a compensating circuit produces in order to compensate said feedback signal Yin Wendu.

Aforesaid LED display system, wherein said gain circuitry comprise that a controller is in order to control the gain of said gain circuitry.

Aforesaid LED display system, wherein each said driver more comprises:

One minimum voltage ST is taken a sample and is exported the minimum value in the voltage on said a plurality of LED pin;

Aforesaid LED display system, wherein said power supply changeover device comprises:

One first comparer, more said feedback signal and one first reference voltage produce one first comparison signal;

One second comparer, more said feedback signal and one second reference voltage produce one second comparison signal;

One logical circuit produces a digital signal according to said first and second comparison signal;

One digital analog converter converts said digital signal into simulating signal;

One error amplifier produces a control signal in order to regulate said low pressure according to said simulating signal and one the 3rd reference voltage.

A kind of driver of LED display system; Said LED display system comprises one to be had one and feedbacks the power supply changeover device of pin in order to provide an output voltage to a plurality of LED; Said driver comprises a plurality of LED pins; One feedback signal node, a minimum voltage Chooser and a gain circuitry is characterized in that:

Said a plurality of LED pin is electrically connected one of them of said a plurality of LED separately;

Said feedback signal node connects said back coupling pin, exports a feedback signal and gives said power supply changeover device to regulate said output voltage;

Said minimum voltage Chooser is by choosing minimum value in the voltage on said a plurality of LED pins;

Said gain circuitry produces said feedback signal according to said minimum value.

Aforesaid driver, wherein said gain circuitry comprises the error that a compensating circuit produces in order to compensate said feedback signal Yin Wendu.

Aforesaid driver, wherein said gain circuitry comprise that a controller is in order to control the gain of said gain circuitry.

A kind of driver of LED display system; Said LED display system comprises one to be had one and feedbacks the power supply changeover device of pin in order to provide an output voltage to a plurality of LED; Said driver comprises a plurality of LED pins, a feedback signal node, a plurality of current sources; An one maximum voltage Chooser and a gain circuitry is characterized in that:

Said a plurality of current source, the said a plurality of LED of each Self Control electric current on one of them, each is self-contained for said a plurality of current sources:

One resistance;

One transistor is connected electrically between one of them and the said resistance of said a plurality of LED pins;

One operational amplifier has one first input electrical connection, one voltage end, one second input electrical connection one node and the output between said resistance and transistor and is electrically connected said transistorized gate;

Said maximum voltage Chooser is by choosing maximal value in the voltage on the gate of the transistor of said a plurality of current sources;

Said gain circuitry produces said feedback signal according to said maximal value.

A kind of driver of LED display system, said LED display system comprise one to have one and feedbacks the power supply changeover device of pin in order to provide an output voltage to a plurality of LED, and said driver comprises a plurality of LED pins; One feedback signal node; One minimum voltage Chooser, a gain circuitry, a current source; One switch and a change-over circuit is characterized in that:

Said gain circuitry produces a direct current signal according to said minimum value;

Said current source is in order to provide an electric current to said feedback signal node;

Said switch is connected electrically between a said feedback signal node and the earth terminal;

Said change-over circuit produces a PWM signal according to said direct current signal and said feedback signal and switches said switch to regulate said feedback signal.

A kind of driver of LED display system; Said LED display system comprises one to be had one and feedbacks the power supply changeover device of pin in order to provide an output voltage to a plurality of LED; Said driver comprises a plurality of LED pins; One feedback signal node, a minimum voltage ST and a gain circuitry is characterized in that:

A plurality of LED pins are electrically connected one of them of said a plurality of LED separately;

One feedback signal node connects said back coupling pin, exports a feedback signal and gives said power supply changeover device to regulate said output voltage;

A kind of control method of LED display system; Said LED display system comprises a power supply changeover device; A plurality of LED and a plurality of driver, each said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately, it is characterized in that said control method may further comprise the steps:

First step: convert DC high voltage at least one dc low-voltage by said power supply changeover device and be supplied to a plurality of LED;

Second step: monitor the voltage on said a plurality of LED pin;

Third step: produce back coupling pin that a feedback signal is connected to said power supply changeover device to regulate said dc low-voltage according at least one of the voltage on said a plurality of LED pins.

Control method of the present invention can also adopt following technical measures further to realize.

Aforesaid control method, wherein said high direct voltage are to be got by alternating voltage conversion.

Aforesaid control method, wherein said at least one according to the voltage on said a plurality of LED pins produce the back coupling pin that said feedback signal is connected to said power supply changeover device and comprise with the step of adjusting said dc low-voltage:

First step: the minimum value of choosing the voltage on said a plurality of LED pin;

Second step: amplify said minimum value with a gain and produce back coupling pin that said feedback signal is connected to said power supply changeover device to regulate said dc low-voltage.

Aforesaid control method wherein also comprises the error that compensates said feedback signal Yin Wendu and produce.

Aforesaid control method wherein more comprises the said gain of control.

Second step: amplify said minimum value with a gain and produce one first signal;

Third step: produce a secondary signal according to said feedback signal on the feedback signal node and said first signal;

The 4th step: control discharging and recharging of said feedback signal node to produce back coupling pin that said feedback signal is connected to said power supply changeover device to regulate said dc low-voltage by said secondary signal.

Aforesaid control method wherein more comprises the said gain of control.

First step: take a sample and export the minimum value of the voltage on said a plurality of LED pin;

Aforesaid control method wherein more comprises the said gain of control.

A kind of control method of LED display system; Said LED display system comprises a power supply changeover device; A plurality of LED and a plurality of driver have one of them that a plurality of LED pins are electrically connected said a plurality of LED separately; Each said driver respectively comprises a plurality of current sources; And each said current source respectively has a resistance, a transistor and is connected electrically between one of them and the said resistance of said a plurality of LED pins and an operational amplifier has one first input and is electrically connected a voltage end, one second input and is electrically connected a node and an output between said resistance and transistor and is electrically connected said transistorized gate, it is characterized in that said control method may further comprise the steps:

Second step: monitor the voltage on said a plurality of transistorized gate;

Third step: produce back coupling pin that a feedback signal is connected to said power supply changeover device to regulate said dc low-voltage according at least one of the voltage on said a plurality of transistorized gates.

Aforesaid control method, wherein said at least one according to the voltage on said a plurality of transistorized gates produce the back coupling pin that said feedback signal is connected to said power supply changeover device and comprise with the step of regulating said dc low-voltage:

First step: the maximal value of choosing the voltage on said a plurality of transistorized gate;

Second step: produce back coupling pin that said feedback signal is connected to said power supply changeover device to regulate said dc low-voltage with the said maximal value of a gain reduction.

Aforesaid control method wherein more comprises the said gain of control.

A kind of driver control method of LED display system; Said LED display system comprises a plurality of LED and a power supply changeover device provides an output voltage to said a plurality of LED; Said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately, it is characterized in that said control method may further comprise the steps:

Second step: amplify said minimum value with a gain and produce back coupling pin that a feedback signal is connected to said power supply changeover device to regulate said output voltage.

Aforesaid control method wherein more comprises the said gain of control.

A kind of driver control method of LED display system; Said LED display system comprises a plurality of LED and a power supply changeover device provides an output voltage to said a plurality of LED; Said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately; And a plurality of current sources; Each said current source respectively has a resistance, a transistor and is connected electrically between one of them and the said resistance of said a plurality of LED pins and an operational amplifier has one first input and is electrically connected a voltage end, one second input and is electrically connected a node and an output between said resistance and transistor and is electrically connected said transistorized gate, it is characterized in that said control method may further comprise the steps:

First step: the maximal value of choosing the voltage on the transistorized gate in said a plurality of current source;

Second step: produce back coupling pin that a feedback signal is connected to said power supply changeover device to regulate said output voltage with the said maximal value of a gain reduction.

Aforesaid control method wherein more comprises the said gain of control.

Third step: the feedback signal of changing on said first signal and the feedback signal node produces a secondary signal;

The 4th step: control discharging and recharging of said feedback signal node according to said secondary signal and produce back coupling pin that said feedback signal is connected to said power supply changeover device to regulate said output voltage.

Aforesaid control method wherein more comprises the said gain of control.

After adopting technique scheme, the driver of LED display system of the present invention and control method thereof and LED display system and control method have the advantage that improves usefulness and reduce cost.

Description of drawings

Fig. 1 is the known LED display system schematics that is applied to billboard;

Fig. 2 is the LED display system schematics;

Fig. 3 is the first embodiment synoptic diagram of led driver among Fig. 2;

Fig. 4 is the first embodiment synoptic diagram of the back coupling mechanism of led driver among Fig. 3;

Fig. 5 is the embodiment synoptic diagram of impact damper among Fig. 4;

Fig. 6 is the second embodiment synoptic diagram of the back coupling mechanism of led driver among Fig. 3;

Fig. 7 is the embodiment synoptic diagram of impact damper among Fig. 6;

Fig. 8 is the 3rd an embodiment synoptic diagram of the back coupling mechanism of led driver in the displayed map 3;

Fig. 9 is the oscillogram of signal among Fig. 8;

Figure 10 is the second embodiment synoptic diagram of led driver among Fig. 2;

Figure 11 is the back coupling schematic diagram of mechanism of led driver among Figure 10;

Figure 12 is another LED display system schematics;

Figure 13 is the partial circuit synoptic diagram of led driver among Figure 12;

Figure 14 is the synoptic diagram of other part of led driver among Figure 13.

Embodiment

Below in conjunction with embodiment and accompanying drawing thereof the present invention is illustrated further.

See also Fig. 2, Fig. 2 is the LED display system schematics at present.As shown in the figure; Said LED display system 200; Wherein exchange and give display panel 204 to direct current transducer 202 with the high direct voltage that alternating voltage converts 20V into, owing to exchange the high direct voltage that direct current transducer 202 is provided 20V, therefore the electric current through line resistance Rs is very little; Thereby reduce the line resistance power consumption that Rs caused, improve the usefulness of LED display system 200.In display panel 204; Direct current converts the high direct voltage of 20V dc low-voltage VLED1 and the VLED2 of 2.4V and 3.8V into to direct current transducer 206, and wherein voltage VLED1 offers redness and green LED light source 208 and 212, and voltage VLED2 then offers blue led light source 216; Each led light source 208 comprises a plurality of LED220; Each led light source 212 comprises a plurality of LED222, and each led light source 216 comprises a plurality of LED224, and a plurality of led drivers 210 are in order to drive a plurality of led light sources 208; A plurality of led drivers 214 are in order to drive a plurality of led light sources 212, and a plurality of led drivers 218 are in order to drive a plurality of led light sources 216.In LED display system 200; Back coupling pin FB reset signal to the direct current of led driver 210,214,218 to direct current transducer 206 to regulate direct current to the output terminal VLED1 of direct current transducer 206 and the voltage on the VLED2; Make it be slightly larger than LED220 in led light source 208,212 and 216,222 and 224 forward bias voltage drop; Therefore can reduce the generation of heat; So need not to use heat absorber, thereby can further improve the usefulness of LED display system 200, also reduced total assembly cost simultaneously; Also because LED display system 200 can suitable adjusting offers LED220,222 and 224 voltage VLED1 and VLED2, therefore can improve LED220,222 and 224 aging.

The first embodiment synoptic diagram of led driver 210 in Fig. 3 displayed map 2.With reference to Fig. 2 and Fig. 3; Led driver 210 is except back coupling pin FB; Also comprise frequency pin CLK in order to receive data frequency, data input pin SDI is in order to receive data, and activation pin OE is in order to receive output enable signal; Data output connecting pin SDO is in order to output data, and pin PLED1, PLED2 ... And PLEDM connects a LED220 separately.In led driver 210; A plurality of current sources 300 connect respectively pin PLED1, PLED2 ... And PLEDM; These current sources 300 can control electric current I LED1 through LED220, ILED2 ... And ILEDM, these current sources 300 of the signal deciding on the activation pin OE are opened or are closed in addition.Each current source 300 comprise transistor 304 and resistance R x1 be connected on pin PLED1, PLED2 ... And between PLEDM one of them and the earth terminal GND, operational amplifier 302 has the gate that non-inverting input connected node N1, inverting input connected node N2 and output terminal connect transistor 304.The first embodiment synoptic diagram of the back coupling of led driver 210 mechanism in Fig. 4 displayed map 3; It comprises the voltage on the minimum voltage Chooser 400 monitoring pin PLED1 to PLEDM; Pin PLED1, PLED2 ... Or the voltage on the PLEDM is more little; The forward bias voltage drop of the LED220 that expression is connected with said pin is big more; Therefore choose minimum value output the voltage of minimum voltage Chooser 400 from pin PLED1 to PLEDM, gain circuitry 402 produces feedback signal VS1 according to the output of minimum voltage Chooser 400.After through gain, feedback signal VS1 will have higher noise tolerance power, so can eliminate the influence of the line resistance of power lead.In gain circuitry 402; The non-inverting input of impact damper 404 connects the output of minimum voltage Chooser 400; Variable resistor RG2 is connected between the output terminal and inverting input of impact damper 404, and resistance R G1 is connected between the inverting input and node N3 of impact damper 404, and the resistance of gain controller 406 control variable resistor RG2 is to change the gain of gain circuitry 402; Switch SW 1 is connected between compensating circuit 408 and the node N3, and switch SW 2 is connected between node N3 and the earth terminal GND.With reference to Fig. 3 and Fig. 4, because the conducting resistance of transistor 304 maybe be with temperature change in the current source 300, therefore when temperature variation, error possibly appear in feedback signal VS1, so in a preferred embodiment, the said error of compensating circuit 408 compensation should be set.The embodiment synoptic diagram of impact damper 404 in Fig. 5 displayed map 4.As shown in Figure 4; Because the back coupling pin FB of a plurality of led drivers 210 is connected in parallel; And the absorption ability of impact damper 404 is as shown in Figure 5 much larger than supply capacity, so direct current will equal the minimum value that these back coupling pins FB goes up feedback signal VS1 to the signal on the back coupling pin FB1 of direct current transducer 206; Also therefore, direct current can provide less to direct current transducer 206 and suitable voltage to led light source 208.Direct current to direct current transducer 206 in, signal and reference voltage VREF that error amplifier 410 is relatively feedback on the pin FB1 produce the output voltage that converter 206 is regulated in an output.

The second embodiment synoptic diagram of the back coupling of led driver 210 mechanism in Fig. 6 displayed map 3; Wherein the voltage Vg1 on all crystals pipe 304 gates in maximum voltage Chooser 500 surveillance maps 3, Vg2 ... And VgM; And therefrom choose maximal value output, gain circuitry 502 produces feedback signal VS2 according to the output of maximum voltage Chooser 500.After through gain, feedback signal VS2 will have higher noise tolerance power, so can eliminate the influence of the line resistance of power lead.In gain circuitry 502; The output of resistance R G1 and RG2 dividing potential drop maximum voltage Chooser 500 produces voltage VD; Impact damper 506 produces feedback signal VS2 according to voltage VD, the resistance of gain controller 504 controlling resistance RG2, and then the input of decision gain circuitry 502 and the ratio of output.The embodiment synoptic diagram of impact damper 506 in Fig. 7 displayed map 6.In Fig. 6; The back coupling pin FB of a plurality of led drivers 210 is connected in parallel; And the supply capacity of impact damper 506 is much larger than the absorption ability; As shown in Figure 7, so direct current will equal the maximal value that these back coupling pins FB goes up feedback signal VS2 to the signal on the back coupling pin FB1 of direct current transducer 206.Direct current to direct current transducer 206 in, error amplifier 508 produces the output voltage of a Signal Regulation direct current to direct current transducer 206 according to the signal and the reference voltage VREF that feedback on the pin FB1.

The 3rd embodiment synoptic diagram of the back coupling of led driver 210 mechanism in Fig. 8 displayed map 3.The oscillogram of signal in Fig. 9 displayed map 8.With reference to Fig. 3 and Fig. 8; Led driver 210 comprises the voltage on the minimum voltage Chooser 600 monitoring pin PLED1 to PLEDM; And therefrom choose minimum value and export; Gain circuitry 602 produces direct current signal VDC according to the output of minimum voltage Chooser 600; Change-over circuit 610 produces one according to the feedback signal VS3 on direct current signal VDC and the back coupling pin FB and has the fixedly PWM signal Spwm of non-working time, and shown in the waveform 620 of Fig. 9, switch 612 is connected feedbacks between pin FB and the earth terminal GND.As shown in Figure 8; The back coupling pin FB of a plurality of led drivers is connected in parallel; And switch 612 is connected between back coupling pin FB and the earth terminal GND; So the absorption ability is much larger than deliverability, this direct current will equal these to the signal on the back coupling pin FB1 of direct current transducer 206 and feedback pin FB the minimum value that goes up feedback signal VS3.With reference to Fig. 8 and Fig. 9, when PWM signal Spwm was high levle, like the time t1 to t2 of Fig. 9, switch 612 cut out (turn off), so 614 pairs of current sources are feedback, and pin FB charges so that feedback signal VS3 rises, shown in the waveform 618 of Fig. 9.Therefore when PWM signal Spwm was low level, like the time t2 to t3 of Fig. 9, switch 612 was opened (turn on), feedback pin FB to be connected to earth terminal GND, so feedback signal VS3 decline.

In gain circuitry 602; The non-inverting input of impact damper 606 connects the output of minimum voltage Chooser 600; Variable resistor RG2 is connected between the output terminal and inverting input of impact damper 606; Resistance R G1 is connected between the inverting input and node N4 of impact damper 606, and the resistance of gain controller 608 control variable resistor RG2 is to change the gain of gain circuitry 602, and switch SW 3 is connected between compensating circuit 604 and the node N4; Switch SW 4 is connected between node N4 and the earth terminal GND, the error that compensating circuit 604 causes because of temperature variation in order to compensation.Direct current to direct current transducer 206 in, error amplifier 616 produces the output voltage of a Signal Regulation direct current to direct current transducer 206 according to the signal and the reference voltage VREF that feedback on the pin FB1.

The second embodiment synoptic diagram of led driver 210 in Figure 10 displayed map 2; It comprises that equally a plurality of current sources 300 are in order to driving LED 220; One controller 700 according to the output enable signal on the activation pin OE produce a plurality of control signal EN1, EN2 ... And ENM, these control signals EN1, EN2 ... And ENM determines whether activation of its current source of controlling 300 separately.Figure 11 shows the embodiment synoptic diagram of the back coupling mechanism of led driver 210 among Figure 10; Wherein minimum voltage ST 702 sampling and output connecting pin PLED1, PLED2 ... Reach the minimum value that PLEDM goes up voltage, gain circuitry 704 produces feedback signal VS4 to feedbacking pin FB according to the output of minimum voltage ST 702.After through gain, feedback signal VS4 will have higher noise tolerance power, so can eliminate the influence of the line resistance of power lead.In gain circuitry 704; The non-inverting input of impact damper 708 connects the output terminal of minimum voltage ST 702; Variable resistor RG2 is connected between the output terminal and inverting input of impact damper 708; Resistance R G1 is connected between the inverting input and node N5 of impact damper 708, and switch SW 5 is connected between compensating circuit 706 and the node N5, and switch SW 6 is connected between node N5 and the earth terminal GND; The resistance of gain controller 710 control variable resistor RG2, and then the gain of decision gain circuitry 704.

In Figure 11; The back coupling pin FB of a plurality of led drivers 210 is connected in parallel; Because the absorption ability of impact damper 708 is much larger than supply capacity; Therefore direct current will equal the minimum value that these back coupling pins FB goes up feedback signal VS4 to the signal on the back coupling pin FB1 of direct current transducer 206, and the circuit of impact damper 708 is as shown in Figure 5.Direct current to direct current transducer 206 in; Preferably; Signal and reference voltage VR1 that hysteresis comparator 712 is relatively feedback on the pin FB1 produce comparison signal Sc1; Signal and reference voltage VR2 that hysteresis comparator 714 is relatively feedback on the pin FB1 produce comparison signal Sc2; Logical circuit 716 produces digital signal SD according to comparison signal Sc1 and Sc2, and digital analog converter 718 transfers digital signal SD to simulating signal SA, and error amplifier 720 comparison simulating signal SA and reference voltage VR3 produce the output voltage of a Signal Regulation converter 206.In other embodiments, also can be directly with feedbacking signal and reference voltage VR3 error originated from input amplifier 720 on the pin FB1 to produce the output voltage of a Signal Regulation converter 206.

In above stated specification, though led driver 210 only is described, those skilled in the art can realize led

driver

214 and 218 according to this.

Figure 12 shows LED display system 800; Wherein exchange direct current transducer 801 is converted alternating voltage into high direct voltage; Main frame 802 output data frequencies, data and output enable signal to direct current are to frequency input pin CLK, data input pin SDI and the activation pin OE of direct current transducer 804; Direct current converts high direct voltage into dc low-voltage VLED to direct current transducer 804 and gives a plurality of led light sources 806; Each led light source 806 comprises the LED808 of a plurality of parallel connections; A plurality of led drivers 810 respectively drive a led light source 806, and in these led drivers 810, first led driver 810 produces digital signal according to data frequency, digital signal and output enable signal from main frame 802 by output connecting pin SDO and gives next led driver 810; Led driver 810 afterwards all is to give next led driver 810 according to the digital signal of a last led driver 810 outputs and from the data frequency and the output enable signal generation digital signal of main frame 802; And the digital signal that last led driver 810 is exported will be feedback to main frame 802, and main frame 802 will be regulated the output voltage V LED of direct current to direct current transducer 804 according to the digital signal of feedbacking, so that output voltage V LED is slightly larger than the forward bias voltage drop of these LED808; Therefore avoid LED808 overheated without heat absorber, so can improve usefulness and reduce cost.

Figure 13 shows the partial circuit synoptic diagram of led driver 810 among Figure 12; It comprises a plurality of pin PLED1, PLED2 ... And PLEDM connects a LED808 separately; A plurality of current sources 812 connect separately a pin PLED1, PLED2 ... Or PLEDM is in order to driving LED 808; One controller 814 according to the output enable signal on the activation pin OE produce a plurality of control signal EN1, EN2 ... And ENM, these control signals EN1, EN2 ... And ENM determines whether activation of its Control current source 812 separately.Figure 14 shows other part synoptic diagram of led driver 810 among Figure 13; With first led driver 810 is example; Led driver 810 also comprise minimum voltage ST 816 sampling and output connecting pin PLED1, PLED2 ... And PLEDM goes up the minimum value of voltage; The output that gain circuitry 818 amplifies minimum voltage ST 816 produces signal VS5; Hysteresis comparator 826 comparison signal VS5 and reference voltage VR1 produce comparison signal Sc3; Hysteresis comparator 828 comparison signal VS5 and reference voltage VR2 produce comparison signal Sc4, and logical circuit 830 produces digital signal S1 delivers to next led driver 810 via pin SDO pin SDI according to the signal on the pin SDI and comparison signal Sc3 and Sc4.Because signal S1 is a digital signal, therefore can avoid hindering the The noise that is produced because of the line of power lead.

In gain circuitry 818; The non-inverting input of impact damper 822 connects the output terminal of minimum voltage ST 816; Variable resistor RG2 is connected between the output terminal and inverting input of impact damper 822; Resistance R G1 is connected between the inverting input and node N6 of impact damper 822, and switch SW 5 is connected between compensating circuit 820 and the node N6, and switch SW 6 is connected between node N6 and the earth terminal GND; The resistance of gain controller 824 control variable resistor RG2, and then the gain of decision gain circuitry 818.

Above embodiment only supplies to explain the present invention's usefulness, but not limitation of the present invention, the technician in relevant technologies field under the situation that does not break away from the spirit and scope of the present invention, can also make various conversion or variation.Therefore, all technical schemes that are equal to also should belong to category of the present invention, should be limited each claim.

Claims

1. a LED display system comprises a plurality of LED, and a plurality of drivers and a power supply changeover device is characterized in that:

Said a plurality of LED is arranged in the said display system;

2. LED display system as claimed in claim 1 is characterized in that, comprises that more a second source converter transfers alternating voltage to said high direct voltage.

3. LED display system as claimed in claim 1 is characterized in that said power supply changeover device receives said high direct voltage, and converts said high direct voltage into two kinds of dc low-voltages, is supplied to different LED respectively.

4. LED display system as claimed in claim 1 is characterized in that, each said driver more comprises:

5. LED display system as claimed in claim 4 is characterized in that said gain circuitry comprises a compensating circuit, the error that produces to compensate said feedback signal Yin Wendu.

6. LED display system as claimed in claim 4 is characterized in that said gain circuitry comprises a controller, to control the gain of said gain circuitry.

7. LED display system as claimed in claim 1 is characterized in that, said each driver more comprises the electric current of the said a plurality of LED of each Self Control of a plurality of current sources on one of them.

8. LED display system as claimed in claim 7 is characterized in that, said a plurality of current sources comprise separately:

One resistance;

9. LED display system as claimed in claim 8 is characterized in that, each said driver more comprises:

10. LED display system as claimed in claim 9 is characterized in that said gain circuitry comprises a controller, to control the gain of said gain circuitry.

11. LED display system as claimed in claim 1 is characterized in that, each said driver more comprises:

12. LED display system as claimed in claim 11 is characterized in that said gain circuitry comprises the error that a compensating circuit produces in order to compensate said feedback signal Yin Wendu.

13. LED display system as claimed in claim 11 is characterized in that, said gain circuitry comprises that a controller is in order to control the gain of said gain circuitry.

14. LED display system as claimed in claim 1 is characterized in that, each said driver more comprises:

15. LED display system as claimed in claim 14 is characterized in that said gain circuitry comprises the error that a compensating circuit produces in order to compensate said feedback signal Yin Wendu.

16. LED display system as claimed in claim 14 is characterized in that, said gain circuitry comprises that a controller is in order to control the gain of said gain circuitry.

17. LED display system as claimed in claim 14 is characterized in that, said power supply changeover device comprises:

18. the driver of a LED display system; Said LED display system comprises one to be had one and feedbacks the power supply changeover device of pin in order to provide an output voltage to a plurality of LED; Said driver comprises a plurality of LED pins; One feedback signal node, a minimum voltage Chooser and a gain circuitry is characterized in that:

19. driver as claimed in claim 18 is characterized in that, said gain circuitry comprises the error that a compensating circuit produces in order to compensate said feedback signal Yin Wendu.

20. driver as claimed in claim 18 is characterized in that, said gain circuitry comprises that a controller is in order to control the gain of said gain circuitry.

21. the driver of a LED display system; Said LED display system comprises one to be had one and feedbacks the power supply changeover device of pin in order to provide an output voltage to a plurality of LED; Said driver comprises a plurality of LED pins, a feedback signal node, a plurality of current sources; An one maximum voltage Chooser and a gain circuitry is characterized in that:

One resistance;

Said maximum voltage Chooser is by choosing maximal value in the voltage on the transistorized gate of said a plurality of current sources;

22. driver as claimed in claim 21 is characterized in that, said gain circuitry comprises that a controller is in order to control the gain of said gain circuitry.

Have one and feedback the power supply changeover device of pin in order to provide an output voltage to a plurality of LED 23. the driver of a LED display system, said LED display system comprise one, said driver comprises a plurality of LED pins; One feedback signal node; One minimum voltage Chooser, a gain circuitry, a current source; One switch and a change-over circuit is characterized in that:

24. driver as claimed in claim 23 is characterized in that, said gain circuitry comprises the error that a compensating circuit produces in order to compensate said feedback signal Yin Wendu.

25. driver as claimed in claim 23 is characterized in that, said gain circuitry comprises that a controller is in order to control the gain of said gain circuitry.

26. the driver of a LED display system; Said LED display system comprises one to be had one and feedbacks the power supply changeover device of pin in order to provide an output voltage to a plurality of LED; Said driver comprises a plurality of LED pins; One feedback signal node, a minimum voltage ST and a gain circuitry is characterized in that:

27. driver as claimed in claim 26 is characterized in that, said gain circuitry comprises the error that a compensating circuit produces in order to compensate said feedback signal Yin Wendu.

28. driver as claimed in claim 26 is characterized in that, said gain circuitry comprises that a controller is in order to control the gain of said gain circuitry.

29. the control method of a LED display system; Said LED display system comprises a power supply changeover device; A plurality of LED and a plurality of driver, each said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately, it is characterized in that said control method may further comprise the steps:

Second step: monitor the voltage on said a plurality of LED pin;

30. control method as claimed in claim 29 is characterized in that, said high direct voltage is to be got by alternating voltage conversion.

31. control method as claimed in claim 29 is characterized in that, said at least one according to the voltage on said a plurality of LED pins produces the back coupling pin that said feedback signal is connected to said power supply changeover device and comprises with the step of adjusting said dc low-voltage:

32. control method as claimed in claim 31 is characterized in that, also comprises the error that compensates said feedback signal Yin Wendu and produce.

33. control method as claimed in claim 31 is characterized in that, more comprises the said gain of control.

34. control method as claimed in claim 29 is characterized in that, said at least one according to the voltage on said a plurality of LED pins produces the back coupling pin that said feedback signal is connected to said power supply changeover device and comprises with the step of adjusting said dc low-voltage:

Third step: produce a secondary signal according to the above feedback signal and said first signal of a feedback signal node;

35. control method as claimed in claim 34 is characterized in that, also comprises the error that compensates said feedback signal Yin Wendu and produce.

36. control method as claimed in claim 34 is characterized in that, more comprises the said gain of control.

37. control method as claimed in claim 29 is characterized in that, said at least one according to the voltage on said a plurality of LED pins produces the back coupling pin that said feedback signal is connected to said power supply changeover device and comprises with the step of adjusting said dc low-voltage:

38. control method as claimed in claim 37 is characterized in that, also comprises the error that compensates said feedback signal Yin Wendu and produce.

39. control method as claimed in claim 37 is characterized in that, more comprises the said gain of control.

40. the control method of a LED display system; Said LED display system comprises a power supply changeover device; A plurality of LED and a plurality of driver have one of them that a plurality of LED pins are electrically connected said a plurality of LED separately; Each said driver respectively comprises a plurality of current sources; And each said current source respectively has a resistance, a transistor and is connected electrically between one of them and the said resistance of said a plurality of LED pins and an operational amplifier has one first input and is electrically connected a voltage end, one second input and is electrically connected a node and an output between said resistance and transistor and is electrically connected said transistorized gate, it is characterized in that said control method may further comprise the steps:

Second step: monitor the voltage on said a plurality of transistorized gate;

41. control method as claimed in claim 40 is characterized in that, said high direct voltage is to be got by alternating voltage conversion.

42. control method as claimed in claim 40; It is characterized in that said at least one according to the voltage on said a plurality of transistorized gates produces the back coupling pin that said feedback signal is connected to said power supply changeover device and comprise with the step of regulating said dc low-voltage:

43. control method as claimed in claim 40 is characterized in that, more comprises the said gain of control.

44. the driver control method of a LED display system; Said LED display system comprises a plurality of LED and a power supply changeover device provides an output voltage to said a plurality of LED; Said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately, it is characterized in that said control method may further comprise the steps:

45. control method as claimed in claim 44 is characterized in that, also comprises the error that compensates said feedback signal Yin Wendu and produce.

46. control method as claimed in claim 44 is characterized in that, more comprises the said gain of control.

47. the driver control method of a LED display system; Said LED display system comprises a plurality of LED and a power supply changeover device provides an output voltage to said a plurality of LED; Said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately; And a plurality of current sources; Each said current source respectively has a resistance, a transistor and is connected electrically between one of them and the said resistance of said a plurality of LED pins and an operational amplifier has one first input and is electrically connected a voltage end, one second input and is electrically connected a node and an output between said resistance and transistor and is electrically connected said transistorized gate, it is characterized in that said control method may further comprise the steps:

48. control method as claimed in claim 47 is characterized in that, more comprises the said gain of control.

49. the driver control method of a LED display system; Said LED display system comprises a plurality of LED and a power supply changeover device provides an output voltage to said a plurality of LED; Said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately, it is characterized in that said control method may further comprise the steps:

50. control method as claimed in claim 49 is characterized in that, also comprises the error that compensates said feedback signal Yin Wendu and produce.

51. control method as claimed in claim 49 is characterized in that, more comprises the said gain of control.

52. the driver control method of a LED display system; Said LED display system comprises a plurality of LED and a power supply changeover device provides an output voltage to said a plurality of LED; Said driver has one of them that a plurality of LED pins are electrically connected said a plurality of LED separately, it is characterized in that said control method may further comprise the steps:

53. control method as claimed in claim 52 is characterized in that, also comprises the error that compensates said feedback signal Yin Wendu and produce.

54. control method as claimed in claim 52 is characterized in that, more comprises the said gain of control.