CN102892222A - Light emitting device and driving circuit thereof - Google Patents
Light emitting device and driving circuit thereof Download PDFInfo
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- CN102892222A CN102892222A CN2012100285952A CN201210028595A CN102892222A CN 102892222 A CN102892222 A CN 102892222A CN 2012100285952 A CN2012100285952 A CN 2012100285952A CN 201210028595 A CN201210028595 A CN 201210028595A CN 102892222 A CN102892222 A CN 102892222A
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Abstract
The invention discloses a light-emitting device and a driving circuit thereof. The driving circuit is used for receiving voltage from a direct current voltage source, and respectively stores the voltage on a plurality of capacitors to supply a plurality of output voltages to a plurality of input ends of the light emitting diode array so as to achieve the purpose of driving the light emitting diode array by constant current, wherein the light emitting diode array is composed of a plurality of light emitting diode chains. The driving circuit comprises a switch unit and a comparison unit. The switch unit comprises a plurality of switches coupled between the direct current voltage source and the input end of the light emitting diode array. The comparison unit comprises a plurality of comparators. Each comparator has a first input terminal for receiving a reference voltage, a second input terminal coupled to an output terminal of a led chain in the led array, and an output terminal coupled to a corresponding switch in the switch unit.
Description
Technical field
The present invention relates to a kind of light-emitting device and drive circuit thereof, wherein this light-emitting device comprises a light emitting diode matrix.
Background technology
Along with liquid crystal display (Liquid Crystal Display, LCD) extensive use in the electronic products such as TV, monitor, notebook computer, mobile phone, PDA (Personal Digital Assistant), the demand that is used for the backlight module of liquid crystal display illumination grows with each passing day.Wherein, light-emitting diode because have low power consumption, high brightness, volume is little and the advantage such as long service life, the backlight module of now liquid crystal display illumination adopts light-emitting diode as light source mostly.
When light-emitting diode uses at backlight module, usually can be composed in series luminous row by a plurality of light-emitting diodes, again by the connection parallel with one another of a plurality of luminous row to consist of a light emitting diode matrix.Each luminous row is called " light-emitting diode chain (LED chain) ", " light-emitting diode chain (LED set) " or " light-emitting diode storehouse (LED bank) " in technical field.In order to light each light-emitting diode in the light-emitting diode chain and to make the luminosity of a plurality of light-emitting diode chains even, this light emitting diode matrix usually can be by deciding voltage system or constant current mode drives.
Fig. 1 illustrates one typically to decide the circuit diagram of the light emitting diode matrix 10 that voltage system drives, and wherein this light emitting diode matrix 10 is to be made of 110 to 140 on a plurality of light-emitting diode chains.With reference to Fig. 1, a DC-DC converter (DC-DC converter) 12 is used to provide a direct current voltage V
REG1Input to this light emitting diode matrix 10.This direct voltage V
REG1Through resistance R
AAnd R
BAfter the dividing potential drop, produce feedback signal V
FB1To this DC-DC converter 12 to set up stable supply voltage.
With reference to Fig. 1, each light-emitting diode chain 110-140 is made of a plurality of light-emitting diodes that are connected in series.Because light-emitting diode has different forward conducting voltage when conducting, therefore when deciding voltage system and drive, each light-emitting diode chain need cooperate a current-limiting resistance (R
1To R
4) with the flow through electric current of each light-emitting diode chain of control, thus the control luminosity.Yet total forward turn-on voltage that this kind type of drive need be looked each light-emitting diode chain is adjusted individually the size of current-limiting resistance, can cause on the implementation the increase of human cost.In addition, in order to light each light-emitting diode chain, direct voltage V
REG1Usually set according to having the highest total forward light-emitting diode chain of turn-on voltage.This kind setting means can cause supply voltage greater than the required voltage of other light-emitting diode chains.Therefore, unnecessary voltage will be consumed on other current-limiting resistance, so that this current-limiting resistance produces thermal losses.
Fig. 2 illustrates the circuit diagram of a light emitting diode matrix 10 that typically drives with constant current mode.With reference to Fig. 2, this light emitting diode matrix 10 is driven by a constant-current driver 20.This constant-current driver 20 comprises a plurality of switch S
ATo S
DWith a plurality of constant current source I
SEach light-emitting diode chain 110 to 140 switch S via correspondence
ATo S
DAnd be connected to constant current source I
SWith reference to Fig. 2, those switch S
ATo S
DReceive a pulse width modulation signal PWM to realize brilliance control by dimming mode (dimming).In addition, this DC-DC converter 12 is according to a feedback signal V
FB2To adjust supply voltage V
REG2Size.For example, this feedback signal V
FB2Can be voltage V
F1To V
F4In minimum voltage, voltage V for example
F1If voltage V
F1Less than a setting voltage, represent the electric current of the light-emitting diode chain 110 of flowing through less than constant current source I
STherefore, this DC-DC converter 12 receives this feedback signal V
FB2After, will improve supply voltage V
REG2To increase voltage V
F1As voltage V
F1When increasing to this setting voltage, this DC-DC converter 12 can stop the increase of output voltage, so that supply voltage V
REG2Keep certain value.
Fig. 3 illustrates an existing constant current source I
SProducing method.With reference to Fig. 3, this constant current source I
SProvided by a current source circuit 30, wherein this current source circuit 30 comprises an operational amplifier OP, a transistor M and a resistance R.The positive input terminal of this operational amplifier OP is connected to a reference voltage V
R, and its output is electrically connected at negative input end by this transistor M.This current source circuit 30 determines reference voltage V according to the brightness of light-emitting diode chain 110
RValue with resistance R.In other words, as supply voltage V
REG2When enough high, the electric current of the light-emitting diode chain 110 of flowing through can equal to flow through the value of resistance R that is reference voltage V
RValue divided by resistance R.Drive in this way this light emitting diode matrix 10, although can avoid the setting of current-limiting resistance, yet, as this supply voltage V
REG2During greater than the required voltage of this drive circuit 20 and other light-emitting diode chains, then unnecessary voltage will be consumed on this transistor, so that this drive circuit 20 produces thermal lossess.
Accordingly, be necessary to propose a kind of drive circuit for light emitting diode matrix, this one drive circuit can provide and make indivedual light-emitting diode chains generations decide indivedual proper voltages of current drives, simultaneously because needn't make operational amplifier and transistor circuit, not only save the power consumption on the lower transistor, more can reach the effect that hypervelocity is decided current drives light-emitting diode chain.
Summary of the invention
The drive circuit that the purpose of this invention is to provide a kind of light emitting diode matrix.Drive circuit of the present invention is in order to receive the voltage from a direct current voltage source, be stored in respectively on a plurality of capacitors to supply a plurality of inputs of a plurality of output voltages to this light emitting diode matrix, reach the purpose of deciding this light emitting diode matrix of current drives, wherein this light emitting diode matrix is made of a plurality of light-emitting diode chains.According to one embodiment of the invention, this drive circuit comprises one first switch element and a comparing unit.This first switch element comprises a plurality of switches between the described input that is coupled to this direct voltage source and this light emitting diode matrix.This comparing unit comprises a plurality of comparators.Each comparator has a first input end receiving a reference voltage, and one second input is being coupled to the output of the light-emitting diode chain in this light emitting diode matrix, and an output is to be coupled to switch corresponding in this first switch element.
Another object of the present invention provides a kind of drive circuit of light emitting diode matrix.A plurality of inputs of this light emitting diode matrix are connected to a plurality of electric capacity and reach via a plurality of switches to receive once the alternating voltage of regulating.A plurality of outputs of this light emitting diode matrix are connected to a plurality of inputs of this drive circuit.This light emitting diode matrix is made of a plurality of light-emitting diode chains.According to one embodiment of the invention, this drive circuit comprises a current source cell and a comparing unit.This current source cell comprises a plurality of constant current sources.Each current source is connected to the output of corresponding light-emitting diode chain so that this light-emitting diode chain one fixed current to be provided.This comparing unit comprises a plurality of comparators.Whether each comparator equals this fixed current in order to the flow through electric current of corresponding light-emitting diode chain of detecting, thereby exports a comparison signal.This comparison signal is in order to control the state of described switch.
Another purpose of the present invention provides a kind of light-emitting device, its receive from once the AC power of regulating with as an input power.This light-emitting device comprises a light emitting diode matrix, a plurality of electric capacity, a plurality of switch and one drive circuit.This light emitting diode matrix is made of a plurality of light-emitting diode chains.This light emitting diode matrix has a plurality of inputs and a plurality of output.Described electric capacity is connected in the described input of this light emitting diode matrix, and described switch is connected between the described input and this AC power of this light emitting diode matrix.This drive circuit comprises a current source cell and a comparing unit.This current source cell comprises a plurality of constant current sources.Each current source is connected to the output of corresponding light-emitting diode chain so that this light-emitting diode chain one fixed current to be provided.This comparing unit comprises a plurality of comparators.Whether each comparator equals this fixed current in order to the flow through electric current of corresponding light-emitting diode chain of detecting, thereby exports a comparison signal.This comparison signal is in order to control the state of described switch.
Description of drawings
By reference above stated specification and following graphic, technical characterictic of the present invention and advantage are obtained to be understood fully.
Fig. 1 illustrates one typically to decide the circuit diagram of the light emitting diode matrix that voltage system drives;
Fig. 2 illustrates the circuit diagram of a light emitting diode matrix that typically drives with constant current mode;
Fig. 3 illustrates the producing method of an existing constant current source;
Fig. 4 shows the block schematic diagram of drive circuit of the light emitting diode matrix of one embodiment of the invention;
Fig. 5 shows the supply power mode of the drive circuit of one embodiment of the invention;
Fig. 6 shows the block schematic diagram of drive circuit of the light emitting diode matrix of one embodiment of the invention;
Fig. 7 shows the block schematic diagram of the charge pump circuit of one embodiment of the invention;
Fig. 8 shows the interchange type of drive schematic diagram of the light emitting diode matrix of one embodiment of the invention; And
Fig. 9 shows the block schematic diagram of the drive circuit of another embodiment of the present invention.
The main element symbol description
10 light emitting diode matrixs
110～140 light-emitting diode chains
12 DC-DC converters
R
1～R
4Current-limiting resistance
R
A～R
BResistance
C
OUTElectric capacity
20 constant-current drivers
S
A～S
BSwitch
I
SCurrent source
The OP operational amplifier
The M transistor
R resistance
40 light emitting diode matrixs
402～406 light-emitting diode chains
42 drive circuits
44 switch elements
442～446 switches
46 comparing units
462～466 comparators
C
1, C
2, C
3, C
LElectric capacity
R resistance
48 circuit for detecting
482 gates
50 dc voltage changers
60 drive circuits
62 charge pump unit
6222 clock generation circuits
S
1～S
7Switch
X
1～X
2Gate
622～624 charge pump circuits
64 switch elements
642～644 switches
80 light emitting diode matrixs
802～808 light-emitting diode chains
82 power supply devices
822 rectification circuits
C
FElectric capacity
84 ' drive circuit
842 current source cells
The IC constant current source
844 comparing units
8442～8448 comparators
C
P1～C
PNElectric capacity
846 current potential converting units
8462～8468 electric potential transducers.
Embodiment
The preferred embodiments of the present invention will cooperate graphic being described in detail as follows, and wherein identical or approximate element shows with similar reference number.
Fig. 4 shows the block schematic diagram of drive circuit 42 of the light emitting diode matrix 40 of one embodiment of the invention.With reference to Fig. 4, a plurality of light-emitting diodes are composed in series a light-emitting diode chain 402 to 406, again by a plurality of light-emitting diode chain 402 to 406 connections parallel with one another to consist of this light emitting diode matrix 40.
With reference to Fig. 4, this drive circuit 42 is connected in a direct current voltage source V
DCAnd between this light emitting diode matrix 40.This drive circuit 42 receives from this direct voltage source V
DCVoltage to supply a plurality of output voltages to this light emitting diode matrix 40.With reference to Fig. 4, this drive circuit 42 comprises a switch element 44 and a comparing unit 46.This switch element 44 comprises a plurality of switches 442 to 446, and wherein each switch is connected between the light-emitting diode chain of this direct voltage and correspondence.This comparing unit 46 comprises a plurality of comparators 462 to 466, and wherein each comparator has a first input end to receive a reference voltage V
R, one is connected to the second input of the output of corresponding light-emitting diode chain, and an output that is connected to switch corresponding in this switch element 44.
With reference to Fig. 4, the output of each light-emitting diode chain is connected to a resistance R, and the input of each light-emitting diode chain is connected to an electric capacity (C
1, C
2And C
3One wherein).When running, the comparator in this comparing unit 46 can compare the voltage of two inputs to determine the state of switch corresponding in this switch element 44.For example, when the voltage of the positive input terminal of comparator 462 during greater than the voltage of negative input end, the switch 442 that this comparator 462 can output one signal be answered with closed pair.Otherwise, when the voltage of the positive input terminal of comparator 462 during less than the voltage of negative input end, this comparator 462 can output one signal to end corresponding switch 442.
Because its conducting voltage V forward of the light-emitting diode that is connected in series in each light-emitting diode chain
FSlightly different, if when the switch in the switch element 44 442 to 446 is kept closed, then the output voltage of each light-emitting diode chain will be not identical.Not identical voltage response so that the output current of each light-emitting diode chain is inconsistent, causes the luminosity of this light emitting diode matrix 40 unequal, even some light-emitting diode chain possibly can't be lit in the resistance R meeting.
In order to solve this problem, the switch 442 to 446 in this switch element 44 is understood according to the voltage on the resistance R and optionally conducting.The explanation as an example of light-emitting diode chain 402 example is when its output voltage V
O1Greater than reference voltage V
RThe time, the expression capacitor C
1On voltage enough supply should light-emitting diode chain 402, so comparator 462 can output one signal with cutoff switch 442.At this moment, the voltage on this light-emitting diode chain 402 is by capacitor C
1Institute provides.Work as capacitor C
1On voltage drop the time, the voltage on the resistance R also descends thereupon.Voltage on resistance R is lower than reference voltage V
RThe time, then comparator 462 can transitions exporting a signal, thereby Closing Switch 442.When switch 442 closure, this light-emitting diode chain 402 will be by direct voltage source V
DCVoltage is provided, and this direct voltage source V
DCCan be simultaneously to capacitor C
1Charge.
Therefore, if this light emitting diode matrix 40 according to this mode drive, the current i of each the light-emitting diode chain in this light emitting diode matrix 40 can keep definite value, and can be expressed as:
In an embodiment of the present invention, this direct voltage source V
DCVoltage can be provided by a direct current electric pressure converter 50, as shown in Figure 5.This dc voltage changer 50 can for, but be not limited to a pressurizer that switches form, it is according to a feedback voltage V
FBWith regulation output voltage V
LEDMagnitude of voltage.With reference to Fig. 5, this drive circuit 42 comprises a circuit for detecting 48 in addition, and it is in order to produce this feedback voltage V
FB
In an embodiment of the present invention, this circuit for detecting 48 is a voltage comparator, and it is the voltage V of the output of this light emitting diode matrix 40 relatively
O1To V
O3For example, as voltage V
O1For in the voltage of described output during minimum value, this feedback signal V
FBBe this voltage V
O1In another embodiment of the present invention, this circuit for detecting 48 is a current comparator, the current value of its each light-emitting diode chain 402 to 406 of relatively flowing through.When the electric current of this light-emitting diode chain 402 of flowing through is minimum value in this light emitting diode matrix 40, this feedback signal V
FBBe the voltage V of the output of this light-emitting diode chain 402
O1
With reference to Fig. 5, this feedback signal V
FBBe sent to the negative input end of the error amplifier OP in this dc voltage changer 50.This error amplifier OP is responsible for amplifying this feedback signal V
FBA reference voltage V built-in with this dc voltage changer 50
REFDifference to produce output signal V
ERTherefore, according to this output signal V
ER, the output voltage V of this dc voltage changer 50
LEDCan be adjusted to provide suitable supply voltage to this light emitting diode matrix 40.Because this feedback signal V
FBBe the minimum voltage value of the output of this light emitting diode matrix 40, or for having the magnitude of voltage of its output of light-emitting diode chain of minimum current value in this light emitting diode matrix 40, so detect than reference voltage V when this dc voltage changer 50
REFLow feedback signal V
FBThe time, it can improve output voltage V
LEDTo promote the output end voltage of this light emitting diode matrix 40.
In another embodiment of the present invention, this direct voltage source V
DCExcept by this dc voltage changer 50, also can be provided by a charge pump (charge pump) circuit.Fig. 6 shows the block schematic diagram of drive circuit 60 of the light emitting diode matrix 40 of one embodiment of the invention.With reference to Fig. 6, this drive circuit 60 comprises a charge pump unit 62 in addition.This charge pump unit 62 comprises a plurality of charge pump circuits 622 to 624, and each charge pump circuit is in order to according to a direct current voltage V
CCTo produce an output voltage corresponding switch to this switch element 44.
Fig. 7 shows the block schematic diagram of the charge pump circuit 622 of one embodiment of the invention.With reference to Fig. 7, this charge pump circuit 622 comprises a clock generation circuit 6222, switch S
1To S
7And capacitor C
B1And C
B2This clock generation circuit 6222 is in order to produce a clock signal clk.This clock signal clk is via gate X
1And X
2The clock signal C K of two responsibility cycle of rear generation not overlapping (non-overlapping)
1And CK
2, in order to control switch S
1To S
7Conducting state.When running, as clock signal CK
1During for logic high potential, switch S
1, S
4, S
5And S
7Conducting, and switch S
2, S
3And S
6Cut-off.Therefore, capacitor C
B1On to be stored pressure reduction be V
CCElectric charge, and capacitor C
B2On to be stored pressure reduction be V
LEDElectric charge.As clock signal CK
2During for logic high potential, switch S
1, S
4, S
5And S
7Cut-off, and switch S
2, S
3And S
6Conducting.Owing to capacitor C this moment
B2Via switch S
2Be coupled to capacitor C
B1The other end, capacitor C
B2The voltage of an end can rise to V
CC+ V
LED
The function mode of this drive circuit 60 now is described with Fig. 6.Suppose that light-emitting diode chain 402 is for having minimum total forward diode chain of turn-on voltage in this light emitting diode matrix 40, and for keeping this light-emitting diode chain 402 1 constant brightness, this drive circuit 60 needs output voltage V SET to the input of this light-emitting diode chain 402 at least.When running, at first the output voltage of this dc voltage changer 50 can rise to this output voltage V SET by zero volt.During this period, the switch 642 in the switch element 64 and 644 and switch element 44 in switch 442 and 444 be closure state.Therefore, capacitor C
1And C
2Can charge to the output voltage V SET that this dc voltage changer 44 provides.After charging is finished, the switch 642 in this switch element 64 and 644 and switch element 44 in switch 442 and 444 will present cut-off state, can be by capacitor C and drive the energy of light-emitting diode chain 402 and 404
1And C
2Institute provides.
Because total forward turn-on voltage of light-emitting diode chain 404 is greater than the always turn-on voltage forward of light-emitting diode chain 402, capacitor C when switch 444 cut-off
2On voltage can't make light-emitting diode chain 404 keep same brightness.Therefore, detect the output end voltage V of light-emitting diode chain 404 when comparator 464
O2Less than reference voltage V
RThe time, this comparator 464 can be exported a signal with switch 444 corresponding to conducting.At this moment, the supply voltage on this light-emitting diode chain 404 will be provided by charge pump circuit 624.This charge pump circuit 624 can be promoted to V with voltage according to above-mentioned switching over action
CC+ V
LEDThereby, the voltage V of raising light-emitting diode chain 404 outputs
O2As output end voltage V
O2Be promoted to reference voltage V
RThe time, this comparator 464 can be exported a signal to end corresponding switch 444.At this moment, the voltage of driving light-emitting diode chain 404 can be by the capacitor C after the charging
2Institute provides.
In an embodiment of the present invention, this direct voltage V
CCValue be total forward difference of conducting voltage of light-emitting diode chain 404 and light-emitting diode chain 402 in the light emitting diode matrix 40.Mode operates according to this, and those light-emitting diode chains 404 and light-emitting diode chain 402 can maintain a constant brightness, and does not have unnecessary thermal losses on the corresponding current-limiting resistance.In another embodiment of the present invention, this direct voltage V
CCValue can be greater than total forward difference of conducting voltage of light-emitting diode chain 404 in the light emitting diode matrix 40 and light-emitting diode chain 402.
In addition, in an embodiment of the present invention, the circuit for detecting 48 of this drive circuit 60 can be implemented by a gate 482.This gate 482 receives the output signal CP of comparator 462 and 464
1And CP
2As signal CP
1And CP
2When being logic high potential, represent that the output end voltage of all light-emitting diode chains is greater than reference voltage V
RSo this gate 482 outputs one logic high potential is so that this dc voltage changer 50 is kept existing output voltage.Otherwise, as signal CP
1And CP
2When having one to be logic low potential, represent that the output end voltage of a certain light-emitting diode chain is not enough, so this gate 482 can be exported a logic low potential, so that this dc voltage changer 50 promotes existing output voltage.
In the above-described embodiments, drive circuit 42 (Fig. 4) and 60 (Fig. 6) are connected between a direct current voltage source V DC and this light emitting diode matrix 40.Therefore, this light emitting diode matrix 40 drives according to a direct current voltage.Yet light emitting diode matrix also can be according to driving once the alternating voltage of regulating.Fig. 8 shows the interchange type of drive schematic diagram of the light emitting diode matrix 80 of one embodiment of the invention.With reference to Fig. 8, this light emitting diode matrix 80 receives the AC power V that regulated from one of this power supply device 82
AC, regWith as input power.This power supply device 82 comprises to receive a rectification circuit 822 of AC power input.This rectification circuit 822 can be a full-wave rectifying circuit or a half-wave rectification circuit, for should light emitting diode matrix 80 1 forward voltages.This power supply device 82 also can comprise a capacitor C who is coupled to this rectification circuit 822
F, the high-frequency noise part that it is only inputted in order to this AC power of filtering.
With reference to Fig. 8, this light emitting diode matrix 80 is comprised of 802 to 808 on a plurality of light-emitting diode chains, and each light-emitting diode chain 802 to 808 is comprised of at least one light-emitting diode series connection.In an embodiment of the present invention, the pattern structure of this light emitting diode matrix 80 cooperates the alternating voltage V that regulated
AC, regWaveform and be embodied as the pattern structure of an approximate string ripple.Yet the present invention should be as limit, and the pattern structure of this light emitting diode matrix 80 can be a square chart spline structure, a triangular graph spline structure maybe can be any geometric pattern structure.With reference to Fig. 8, the input of this light emitting diode matrix 80 is connected to a plurality of capacitor C
P1To C
PNAnd via a plurality of interrupteur SW
1To SW
NBe connected to this alternating voltage V
AC, reg, and a plurality of outputs of this light emitting diode matrix 80 are connected to a plurality of inputs of this drive circuit 84.
With reference to Fig. 8, this drive circuit 84 comprises a current source cell 842 and a comparing unit 844.This current source cell 842 comprises a plurality of constant current source I
C, each constant current source I
CBe connected to the output of corresponding light-emitting diode chain so that this light-emitting diode chain one fixed current to be provided.This comparing unit 844 comprises a plurality of comparators 8442 to 8448, and whether each comparator equals constant current source I in order to the flow through electric current of corresponding light-emitting diode chain of detecting
CThe predetermined current value.Those comparators 8442 to 8448 are exported comparison signal CT according to the result of detecting
1To CT
N, and those comparison signals CT
1To CT
NIn order to control those interrupteur SW
1To SW
NState.
In another embodiment of the present invention, those comparison signals CT
1To CT
NCan be again via a current potential converting unit 846 with the changing voltage current potential, as shown in Figure 9.With reference to Fig. 9, this current potential converting unit 846 comprises a plurality of electric potential transducers 8462 to 8468, and each electric potential transducer is in order to the voltage potential of the output signal of changing corresponding comparator.For example, electric potential transducer 8462 receives the output signal CT of comparator 8442
1Rear output signal D
1In the present embodiment, output signal CT
1The voltage potential of logic high signal about 5V, and signal D
1The voltage potential of logic high signal can be promoted to about 110V with interrupteur SW corresponding to conducting
1
The function mode of this drive circuit 84 now is described with Fig. 8.When comparator 8442 detects the electric current of the light-emitting diode chain 802 of flowing through less than constant current source I
CThe predetermined current value time, this comparator 8442 can output comparison signal CT
1To interrupteur SW
1, with actuating switch SW
1Work as interrupteur SW
1During conducting, this alternating voltage V
AC, regCan be to capacitor C
P1Charge, and this alternating voltage V
AC, regCan supply voltage to this light-emitting diode chain 802 with the flow through electric current of light-emitting diode chain 802 of raising.The electric current that detects the light-emitting diode chain 802 of flowing through when comparator 8442 equals constant current source I
CThe predetermined current value time, this comparator 8442 can output comparison signal CT
1To interrupteur SW
1, with cutoff switch SW
1At this moment, capacitor C
P1Can provide the light-emitting diode chain 802 1 driving voltages.By above-mentioned function mode, those light-emitting diode chains 802 to 808 in this light emitting diode matrix 80 can pass through those capacitor C
P1To C
PNStored electric charge and at alternating voltage V
AC, regThe whole cycle in conducting, and can keep uniform brightness.
Technology contents of the present invention and technical characterstic disclose as above, yet those skilled in the art still may be based on teaching of the present invention and announcements and done all replacement and modifications that does not deviate from spirit of the present invention.Therefore, protection scope of the present invention should be not limited to those disclosed embodiments, and should comprise various do not deviate from replacement of the present invention and modifications, and is contained by claims.
Claims (25)
1. the drive circuit of a light emitting diode matrix, in order to receive voltage from a direct current voltage source to supply a plurality of inputs of a plurality of output voltages to this light emitting diode matrix, wherein this light emitting diode matrix is made of a plurality of light-emitting diode chains, and this drive circuit comprises:
One first switch element, it comprises a plurality of switches between the described input that is coupled to this direct voltage source and this light emitting diode matrix; And
One comparing unit, it comprises a plurality of comparators, each comparator has a first input end to receive a reference voltage, one second input is being coupled to the input of the light-emitting diode chain in this light emitting diode matrix, and an output is to be coupled to switch corresponding in this first switch element.
2. the drive circuit of light emitting diode matrix according to claim 1, wherein the output of each light-emitting diode chain is connected to a resistance, and the input of each light-emitting diode chain is connected to an electric capacity.
3. the drive circuit of light emitting diode matrix according to claim 1, wherein when the voltage of arbitrary its first input end of comparator in this comparing unit during greater than the voltage of the second input, the supply voltage of the light-emitting diode chain that this comparator connects is provided by this direct voltage source.
4. the drive circuit of light emitting diode matrix according to claim 2, wherein when the voltage of arbitrary its first input end of comparator in this comparing unit during less than the voltage of the second input, the supply voltage of the light-emitting diode chain that this comparator connects is provided by this electric capacity.
5. the drive circuit of light emitting diode matrix according to claim 2, wherein the voltage of this direct voltage source is provided by a direct current electric pressure converter, and the voltage that this dc voltage changer is exported is regulated according to a feedback signal.
6. the drive circuit of light emitting diode matrix according to claim 5, wherein this drive circuit also comprises a circuit for detecting so that this feedback signal to be provided.
7. the drive circuit of light emitting diode matrix according to claim 6, wherein this circuit for detecting is exported this feedback signal according to the magnitude of voltage of the described output of this light emitting diode matrix.
8. the drive circuit of light emitting diode matrix according to claim 6, wherein this circuit for detecting is exported this feedback signal according to the current value of the described light-emitting diode chain of flowing through in this light emitting diode matrix.
9. the drive circuit of light emitting diode matrix according to claim 5, wherein this drive circuit also comprises a charge pump unit, and the voltage of this direct voltage source is provided by this dc voltage changer or this charge pump unit.
10. the drive circuit of light emitting diode matrix according to claim 9, wherein this charge pump unit comprises a plurality of charge pump circuits, each charge pump circuit in order to according to one first direct voltage to produce an output voltage corresponding switch to this first switch element, wherein this its value of the first direct voltage is equal to or greater than total forward difference of turn-on voltage of each light-emitting diode chain in this light emitting diode matrix.
11. the drive circuit of light emitting diode matrix according to claim 9, wherein when the voltage of arbitrary its first input end of comparator in this comparing unit during greater than the voltage of the second input, the supply voltage of the light-emitting diode chain that this comparator connects is provided by charge pump circuit corresponding in this charge pump unit.
12. the drive circuit of light emitting diode matrix according to claim 9, wherein when the voltage of arbitrary its first input end of comparator in this comparing unit during less than the voltage of the second input, the supply voltage of the light-emitting diode chain that this comparator connects is provided by this electric capacity.
13. the drive circuit of light emitting diode matrix according to claim 9, wherein this drive circuit also comprises a second switch unit, and this second switch unit comprises a plurality of switches that are coupled between this direct voltage source and this first switch element.
14. the drive circuit of light emitting diode matrix according to claim 6, wherein this circuit for detecting is exported this feedback signal according to the output signal of the described comparator in this comparing unit.
15. the drive circuit of a light emitting diode matrix, a plurality of inputs of this light emitting diode matrix are connected to a plurality of electric capacity and reach via a plurality of switches to receive once the alternating voltage of regulating, and a plurality of outputs of this light emitting diode matrix are connected to a plurality of inputs of this drive circuit, wherein this light emitting diode matrix is made of a plurality of light-emitting diode chains, and this drive circuit comprises:
One current source cell comprises a plurality of constant current sources, and each current source is connected to the output of corresponding light-emitting diode chain so that this light-emitting diode chain one fixed current to be provided; And
One comparing unit comprises a plurality of comparators, and whether each comparator equals this fixed current in order to the flow through electric current of corresponding light-emitting diode chain of detecting, thereby exports a comparison signal;
Wherein, this comparison signal is in order to control the state of described switch.
16. the drive circuit of light emitting diode matrix according to claim 15, wherein the pattern structure of this light emitting diode matrix is the pattern structure of a square chart spline structure, a triangular graph spline structure or an approximate string ripple.
17. the drive circuit of light emitting diode matrix according to claim 15, wherein when the electric current of the arbitrary light-emitting diode chain in this light emitting diode matrix of flowing through equals this fixed current, the comparator that this light-emitting diode chain is corresponding is exported a signal ending corresponding switch, and the supply voltage of this light-emitting diode chain is provided by the electric capacity of correspondence.
18. the drive circuit of light emitting diode matrix according to claim 15, wherein when the electric current of the arbitrary light-emitting diode chain in this light emitting diode matrix of flowing through during less than this fixed current, the comparator that this light-emitting diode chain is corresponding is exported the switch that a signal is answered with closed pair, and the supply voltage of this light-emitting diode chain is provided by this AC power.
19. the drive circuit of light emitting diode matrix according to claim 15, also comprise a current potential converting unit that is connected in this comparator unit, this current potential converting unit comprises a plurality of electric potential transducers, and each electric potential transducer is in order to the voltage potential of the output signal of changing corresponding comparator.
20. a light-emitting device, its receive from once the AC power of regulating with as an input power, comprise:
One light emitting diode matrix is made of a plurality of light-emitting diode chains, and this light emitting diode matrix has a plurality of inputs and a plurality of output;
A plurality of electric capacity are connected in the described input of this light emitting diode matrix;
A plurality of switches are connected between the described input and this AC power of this light emitting diode matrix; And
One drive circuit comprises:
One current source cell comprises a plurality of constant current sources, and each current source is connected to the output of corresponding light-emitting diode chain so that this light-emitting diode chain one fixed current to be provided; And
One comparing unit comprises a plurality of comparators, and whether each comparator equals this fixed current in order to the flow through electric current of corresponding light-emitting diode chain of detecting, thereby exports a comparison signal;
Wherein, this comparison signal is in order to control the state of described switch.
21. light-emitting device according to claim 20, the voltage after wherein should being a full-wave rectification through the voltage that the AC power of regulating is exported or the voltage after the half-wave rectification.
22. light-emitting device according to claim 20, wherein the pattern structure of this light emitting diode matrix is the pattern structure of a square chart spline structure, a triangular graph spline structure or an approximate string ripple.
23. light-emitting device according to claim 20, wherein when the electric current of the arbitrary light-emitting diode chain in this light emitting diode matrix of flowing through equals this fixed current, the comparator that this light-emitting diode chain is corresponding is exported a signal ending corresponding switch, and the supply voltage of this light-emitting diode chain is provided by the electric capacity of correspondence.
24. light-emitting device according to claim 20, wherein when the electric current of the arbitrary light-emitting diode chain in this light emitting diode matrix of flowing through during less than this fixed current, the comparator that this light-emitting diode chain is corresponding is exported the switch that a signal is answered with closed pair, and the supply voltage of this light-emitting diode chain is provided by this AC power.
25. light-emitting device according to claim 20, wherein this drive circuit also comprises a current potential converting unit that is connected in this comparator unit, this current potential converting unit comprises a plurality of electric potential transducers, and each electric potential transducer is in order to the voltage potential of the output signal of changing corresponding comparator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW100125379A TW201306642A (en) | 2011-07-19 | 2011-07-19 | Lighting apparatus and driving circuit thereof |
| TW100125379 | 2011-07-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102892222A true CN102892222A (en) | 2013-01-23 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012100285952A Pending CN102892222A (en) | 2011-07-19 | 2012-02-09 | Light emitting device and driving circuit thereof |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN102892222A (en) |
| TW (1) | TW201306642A (en) |
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| CN106531091A (en) * | 2015-09-15 | 2017-03-22 | 瑞鼎科技股份有限公司 | Driving circuit applied to liquid crystal display device |
| CN110635351A (en) * | 2018-06-21 | 2019-12-31 | 意法半导体(R&D)有限公司 | Laser diode current driving device |
| WO2024087396A1 (en) * | 2022-10-24 | 2024-05-02 | Dynascan Technology Corp. | Display apparatus including led array |
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| CN106531091B (en) * | 2015-09-15 | 2019-07-26 | 瑞鼎科技股份有限公司 | Driving circuit applied to liquid crystal display device |
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| WO2024087396A1 (en) * | 2022-10-24 | 2024-05-02 | Dynascan Technology Corp. | Display apparatus including led array |
Also Published As
| Publication number | Publication date |
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| TW201306642A (en) | 2013-02-01 |
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