CN202261969U - LED device - Google Patents
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- CN202261969U CN202261969U CN2011203601844U CN201120360184U CN202261969U CN 202261969 U CN202261969 U CN 202261969U CN 2011203601844 U CN2011203601844 U CN 2011203601844U CN 201120360184 U CN201120360184 U CN 201120360184U CN 202261969 U CN202261969 U CN 202261969U
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Abstract
The utility model discloses an LED device comprising a rectifier circuit, an LED lamp strip, a constant-current source connected in series between the rectifier circuit and the LED lamp strip, and a switch control unit, wherein the LED lamp strip is divided into n groups; each group of the LED lamp strip is connected in parallel with a control switch Ki, and the control switch Ki is connected with the switch control unit; and the number of LED lamps in the i+1st group of the LED lamp strip is larger than or equal to that of the LED lamps in the ith group. In the LED device provided by the utility model, the LED lamp strip is divided into the n groups, LED lamps with different numbers are arranged in each group of the LED lamp strip, and the connection/disconnection of each group of the LED lamp is controlled via the switches connected in parallel, the circuit design is simplified, and the power consumption is lowered; and besides, the LED device utilizes a voltage comparator and an up-down counter to directly detect voltage difference at the two ends of the constant-current source and control the switch of each group of the LED lamp strip, and accordingly, the circuit design is simplified, and the influence of the LED forward voltage drop discreteness is avoided.
Description
Technical field
The utility model relates to a kind of light-emitting device, relates in particular to a kind of LED matrix.
Background technology
LED (light-emitting diode) because energy-saving and environmental protection, life-span are long etc. characteristics be called as the 4th generation green illumination light source.The voltage-sensitive characteristic requirements of LED is carried out well-designed to the LED drive unit, otherwise small voltage increment just possibly cause the rapid increase of electric current.Inappropriate driving design not only causes extra power consumption, and because efficient reduces, and heating increases, causes the LED junction temperature to raise, and directly influences its useful life.Because the These characteristics of LED, common LED adopt usually DC power supply especially constant-current source drive.When the occasion that is used to throw light on etc. by ac power supply, often through supply convertor alternating current is become earlier and be used further to LED behind the low-voltage DC and drive, cause that LED drive unit volume is big, efficient is poor, cost is high, hindered LED universal at lighting field.
Chinese patent number is 200710142585.0; The utility model patent that name is called " device and the method that are used for driving LED " discloses LED matrix and the driving method thereof that a kind of AC power drives; As shown in Figure 1; Wherein, external AC power supply 100 is after full-wave rectifying circuit 101 rectifications, and gained voltage (below be called commutating voltage) provides drive current through floating current source 102 for led array 103.Control circuit 200 detects the height of commutating voltage and passes through the number of the break-make of control respective switch with the luminous LED of adjustment actual participation.Control circuit 200 comprises low-voltage dc power supply 201, reference resistance row 202, comparator 203, logic selection circuit 204 and switching circuit 205.Current-limiting resistance 104 is with voltage stabilizing didoe 201 and keep capacitor 106 to constitute low-voltage dc power supply, is control circuit 200 power supplies.Reference resistance row 202 comprise N+1 divider resistance 202
0~202
n, be used to produce one group of reference voltage V ref from low to high
0~Vref
N-1Voltage divider 105 is used for said commutating voltage is detected; Its detected value Vsense compares with said reference voltage respectively through one group of comparator 203; Its output selects the break-make of the corresponding control switch in 204 pairs of switching circuits 205 of circuit to control through logic: when commutating voltage is higher, plurality purpose LED is lighted; When commutating voltage is low, fewer purpose LED is lighted, thereby make the maximum number of the LED that the LED number that any time lights and the supply voltage in this moment can light equate the driving efficient of raising device.
Not enough below this prior art exists: at first, its needed control signal is more, the control circuit complex structure.Although can through with control switch the parallelly connected single led quantity that the lamp string that is connected into by a plurality of LED reduces required control signal that replaces with; For example the LED quantity in the LED lamp string of each control switch parallel connection is increased to 10 by 1; Then can required control signal be reduced to originally 1/10th, but correspondingly can cause the driving efficient of device to reduce.Secondly; The forward voltage drop of LED has discreteness; In process of production through LED is screened stepping; Perhaps in integrated chip manufacturing process, the forward voltage drop basically identical of LED in the same device can be guaranteed, but the consistency of LED forward voltage drop between the device of different batches in the batch production process can't be guaranteed through control process parameters.Simultaneously, because commutating voltage and reference voltage are compared, rather than the actual forward voltage drop value of itself and LED compared, deviation will inevitably take place in its result.When the reference voltage value of setting is lower than actual value, will cause constant-current source to be operated in under-voltage condition, make drive current on the low side, the LED luminance shortage; When the reference voltage value of setting was higher than actual value, the voltage that has more was directly shared by constant-current source, will cause constant-current source to be operated in overvoltage condition, made heating increase, and efficient reduces, and brought the problem in useful life of power consumption, temperature rise and LED thus.The LED number of lighting more for a long time situation can become more obvious.Therefore, need in process of production reference voltage to be adjusted, to reduce the influence that is brought by the discreteness of LED forward voltage drop, this will be unfavorable for batch machining, and cause cost to increase.
Summary of the invention
The utility model technical problem to be solved provides a kind of LED matrix, simplifies circuit design, reduce power consumption, and its operating state does not receive the influence of LED forward voltage drop discreteness.
The utility model is to solve the problems of the technologies described above the technical scheme that adopts to provide a kind of LED drive unit, comprises rectification circuit, LED lamp string, is connected on constant-current source and switch control unit between said rectification circuit and the LED lamp string, wherein; Said LED lamp string is divided into the n group, and the connection in series-parallel of every group of LED lamp has control switch Ki, and said control switch Ki links to each other with switch control unit; LED lamp number is more than or equal to LED lamp number in the i group in the i+1 group; I is an integer, and n is a natural number, i < n.
Above-mentioned LED drive unit, wherein, said switch control unit comprises first voltage comparator, second voltage comparator and forward-backward counter; The input of said constant-current source links to each other with the input in the same way of said first voltage comparator, the reverse input end of second voltage comparator respectively; The reverse input end input reference upper voltage limit value Vmax of said first voltage comparator; The INC end of output and forward-backward counter links to each other; The input reference of the input in the same way lower voltage limit value Vmin of said second voltage comparator, the DEC end of output and forward-backward counter links to each other; The output of said forward-backward counter links to each other with control switch successively.
Above-mentioned LED drive unit, wherein, in the said i group in the LED lamp string LED lamp number be 2
i, the value of i is 0,1 ..., n-1.
The utility model contrast prior art has following beneficial effect: the LED matrix that the utility model provides; LED lamp string is divided into groups; Every group of LED that different numbers can be set; And control the current switching of every group of LED lamp string respectively through paralleling switch, thus simplify circuit design, reduce power loss.In addition; The two ends pressure reduction that the utility model directly detects constant-current source through further working voltage comparator and forward-backward counter is controlled lighting of every group of LED lamp string and is extinguished; Further simplify circuit design; And make constant-current source when keeping low-power consumption, its operating state does not receive the influence of LED forward voltage drop discreteness.
Description of drawings
Fig. 1 is existing LED driving device structure sketch map;
Fig. 2 is the utility model LED drive unit first example structure sketch map;
Fig. 3 is the utility model LED drive unit second example structure sketch map;
Fig. 4 is the constant-current source circuit structural representation in the utility model LED drive unit;
Fig. 5 is the electric current constant-source with adjustable electrical block diagram in the utility model drive unit;
Fig. 6 is a way control switch electrical block diagram in the utility model LED drive unit;
Fig. 7 is used to explain that control signal is that the output valve of binary counter and the state of control switch and each LED light/extinguish the corresponding relation sketch map of situation under 3 tunnel the situation;
Fig. 8 is that counter is according to output valve and the state of control switch and the corresponding relation sketch map that each LED lighted/extinguished situation of custom coding mode under 3 tunnel the situation for control signal.
Among the figure:
10 external AC power supplies, 11 rectification circuits, 12 LED lamp strings
13 constant-current sources, 14 switch control units, 15 low-voltage dc power supplies
21 first voltage comparators, 22 second voltage comparators, 23 forward-backward counters
31 divider resistance row, 32 comparator row, 33 encoders
40 constant-current source circuits, 50 electric current adjustable constant-flow sources, 51 voltage comparators
60 1 way control switch, 61 not gates, 100 external ACs
101 rectification circuits, 102 floating current sources, 103 led array
104 current-limiting resistors, 105 voltage dividers 106 keep capacitor
200 control circuits, 201 voltage stabilizing didoes, 202 reference resistances row
203 comparators, 204 logics are selected circuit 205 switching circuits.
Embodiment
Below in conjunction with accompanying drawing and embodiment the utility model is done further to describe.
Fig. 2 is the LED driving device structure sketch map of the utility model first execution mode.
See also Fig. 2, the LED matrix that the utility model provides comprises rectification circuit 11, LED lamp string 12, is connected on constant-current source 13 and switch control unit 14 between said rectification circuit 11 and the LED lamp string 12.Wherein, said LED lamp string 12 is divided into the n group, and the connection in series-parallel of every group of LED lamp has control switch, and said control switch links to each other with switch control unit 14, and LED lamp number is more than or equal to LED lamp number in the i-1 group in the i group, and i, n are natural number, 0 ≤i < n.
The external AC power supply 10 of Fig. 2 can be identical with existing structure shown in Figure 1.In this execution mode, what can adopt is the mains ac power supply of 220V, 50Hz, or the AC power of other form.
Directly parallelly connected after constant-current source 13 is connected with LED lamp string 12 with the output of rectification circuit 11, for LED lamp string 12 provides constant drive current.
In above-mentioned first embodiment, external AC power supply 10 obtains commutating voltage after rectification circuit 11 rectifications, and it provides constant drive current through constant-current source 13 for LED lamp string 12.
Simultaneously, the two ends pressure reduction of constant-current source 13 one tunnel and given reference voltage higher limit Vmax relatively, its as a result control counter 23 add up; Another road and given reference voltage lower limit Vmin compare, and it is control counter 23 tired subtracting as a result.The n of counter 23 output is controlled the break-make of a corresponding n control switch respectively.
Be output as example with binary mode, the count value of forward-backward counter 23 is pressed the binary coding mode by n output D
0~D
N-1Output is wherein with output D
iCorresponding control switch K
iThe LED number of connecting in parallelly connected one group of LED lamp string be 2
iIndividual, work as D
iOutput valve be 1 o'clock, corresponding with it control switch K
iBreak off, make and control switch K
i2 of parallel connection
iIndividual LED lights; Work as D
iOutput valve be 0 o'clock, corresponding with it control switch K
iConducting makes and control switch K
i2 of parallel connection
iIndividual LED extinguishes.So the LED sum of being lighted in the LED lamp string 12 equates with the count value of forward-backward counter 23.Because said forward-backward counter 23, makes that the luminous LED number of actual participation also correspondingly changes according to the mode of increase and decrease one by one in the LED lamp string 12 according to adding up or the tired mode that subtracts is worked.When the two ends of constant-current source 13 pressure reduction is higher than Vmax (for example 4.0V); Forward-backward counter 23 adds up and makes that participating in luminous LED number adds up; To produce forward voltage drop Vf (for example 3.3V) owing to participate in the two ends of luminous LED, so cause the two ends differential pressure step by step of constant-current source 13 to descend: luminous LED is participated in one of every increase, and the two ends pressure reduction of constant-current source 13 just reduces Vf; When it was lower than Vmax, forward-backward counter 23 stopped to add up; When the two ends of constant-current source 13 pressure reduction is lower than Vmin (for example 0.5V); Forward-backward counter 23 is tired to be subtracted and makes and participate in that luminous LED number is tired to be subtracted; Have forward voltage drop Vf owing to participate in the two ends of luminous LED, so cause the two ends differential pressure step by step of constant-current source 13 to increase: luminous LED is participated in one of every minimizing, and the two ends pressure reduction of constant-current source 13 just increases Vf; When it was higher than Vmin, forward-backward counter 23 stopped tired subtracting.Like this; The two ends pressure reduction of constant-current source 13 is between the reference voltage higher limit Vmax and lower limit Vmin of setting all the time; And do not receive the influence of LED forward voltage drop discreteness; Make constant-current source 13 when constant drive current is provided, keep minimum power consumption, thereby improve the driving efficient of whole LED device.
Be output as example with the custom coding mode, adopt the 220V external AC power supply, the about 310V of the peak value of its commutating voltage can drive the LED of 94 about 3.3V of forward voltage drop.With these 94 LED series connection, be divided into 7 groups, control switch of every group of LED lamp connection in series-parallel, each LED number of organizing in the LED lamp string is followed successively by 1,2,4,8,16,32,31.Said forward-backward counter 23 adds up between 0~94 or tires out and subtracts counting, and corresponding 7 outputs are followed successively by D
0~D
6, as the count value N of forward-backward counter 23<64 o'clock, corresponding output valve D=N was as count value N>=64 o'clock, its corresponding output valve D=N+33, with the binary code that calculates the gained output valve as self-defined output code by output D
0~D
6Output.For example, when N=65, corresponding output valve D=65+33=98, its corresponding output code is 1100010, the LED that is lighted adds up to 31+32+0+0+0+2+0=65.So, through 7 output D of forward-backward counter 23
0~D
67 corresponding control switch K
0~K
6The LED number of being lighted equates with the count value of forward-backward counter 23.
According to the utility model, n way control switch and control signal thereof can be to reaching 2
n-1 LED controls; And need not for each LED one tunnel control signal and control switch to be provided; For example, 8 way control switch and control signal thereof just can be controlled maximum 255 LED, and this control signal and control switch quantity that makes that same number of LED is required greatly reduces; Thereby reduce the complexity of control circuit, simplify circuit design.
In addition, in the utility model the end of constant-current source is pressed as the foundation that the luminous LED number of actual participation is adjusted, come down to difference with the actual forward pressure drop of commutating voltage and LED lamp string as the foundation of adjusting the luminous LED number of actual participation.When the actual forward pressure drop of LED (perhaps owing to light modulation makes the actual forward pressure drop of LED reduce) on the low side; The end of constant-current source is pressed and is increased, and trigger the add up number of the LED that makes that actual participation is luminous of forward-backward counter through upper limit comparator also increases thereupon; In like manner; When the actual forward pressure drop of LED higher (perhaps owing to light modulation makes the actual forward pressure drop of LED raise); The end of constant-current source is pressed and is decreased, and triggers the tired number that subtracts the LED that makes that actual participation is luminous of forward-backward counter through the lower limit comparator and also reduces thereupon.Like this, according to the LED drive unit of the utility model, said constant-current source is when providing constant drive current, and the operating state of its low-power consumption does not receive the influence of LED forward voltage drop discreteness.Simultaneously, to the response for changing in the whole voltage range of commutating voltage, and a plurality of reference voltages and for each reference voltage disposes one road comparator need not be set, make circuit design be able to further simplification by two comparators.
Fig. 3 is the structural representation of the LED drive unit of the utility model second execution mode.
With reference to figure 3, this execution mode has removed first comparator 21, second comparator 22 and forward-backward counter 23 on the basis of Fig. 2, increased divider resistance row 31, comparator row 32, encoder 33 and divider resistance R2, R3 simultaneously.Can use and the identical structure shown in Fig. 2 for the structure of other part.
Wherein, Divider resistance row 31 are used to generate K different reference voltage; Comprise K+1 divider resistance 31_0~31_K; Be set between the power supply terminal VCC and GND of low-voltage dc power supply 15, the upper end of the resistance 31_K of top side is connected with power supply terminal VCC, and the lower end of the resistance 31_0 of lower side is connected with power supply terminal GND.Total K tie point between K+1 the divider resistance, with the voltage on this K tie point as K reference voltage V ref0~VrefK-1, here, Vref0 Vref1 ... < VrefK-1.
Divider resistance R2 and R3 are used for said commutating voltage is carried out dividing potential drop, and wherein, divider resistance R2 is with after R3 connects, and is parallelly connected with commutating voltage.The upper end of divider resistance R2 is connected with the positive pole of rectification circuit 11 outputs, and the lower end of divider resistance R3 is connected with the negative pole of rectification circuit 11 outputs.Commutating voltage Vs after the tie point output dividing potential drop of divider resistance R2 and R3 is used for comparing with each reference voltage.
The input of encoder 33 is connected with the output of each comparator in the comparator row 32, is used for K input signal encoded, and its n output D0~Dn-1 is connected with the control end of control switch K0~Kn-1 respectively, is used to control the break-make of respective switch.
With the binary coding mode is example; When the commutating voltage Vs after the dividing potential drop is higher than i reference voltage V refi and is lower than i+1 reference voltage V ref (i+1) (wherein 0 ≤i < K); Comparator 32_0~32_i in the comparator row 32 is i+1 comparator output high level altogether; The binary code of encoder output i+1, the break-make of control respective switch makes that i+1 LED lighted in the LED lamp string.
Like this; The resistance of suitably adjusting each divider resistance in the divider resistance row 31 is to be provided with the reference voltage of an appropriate; The maximum number of the LED that the LED sum and the commutating voltage that can guarantee to light in any time LED lamp string can be lighted equates, thus the driving efficient of raising LED matrix.
Fig. 4 is the example of the constant-current source circuit of Fig. 2, LED drive unit shown in Figure 3, and constant-current source circuit 40 comprises triode Q41, Q42, and resistance R 41, R42 (its resistance is respectively r1, r2, and r1>> r2).Wherein, The collector electrode of triode Q41 links to each other with the upper end of resistance R 41 and the input of electric current; The base stage of triode Q41 links to each other with the lower end of resistance R 41 and the collector electrode of triode Q42; The emitter of triode Q41 links to each other with the base stage of triode Q42 and the upper end of resistance R 42, and the lower end of R42 links to each other with the emitter of triode Q42 and the output of electric current.
In formation shown in Figure 4, the base current of triode Q41 is provided through resistance R 41 by current input terminal, so triode Q41 is able to conducting, and its emitter current resistance R 42 of flowing through, and produce voltage drop at the two ends of R42.Rising along with resistance R 42 ends pressure; When it equals the forward conduction voltage Vbe between the base-emitter of triode Q42; Triode Q42 conducting is shunted the base current of triode Q41, thereby stops the further conducting of triode Q41; Make the electric current maximum from the current input terminal to the current output terminal be restricted to Vbe/r2, play the effect of constant-current source.
Fig. 5 is the example of electric current constant-source with adjustable circuit, and electric current adjustable constant-flow source 50 comprises triode Q41, resistance R 41, R42 (its resistance is respectively r1, r2, and r1>> r2) and voltage comparator 51.Wherein, The collector electrode of triode Q41 links to each other with the upper end of resistance R 41 and the input of electric current; The base stage of triode Q41 links to each other with the lower end of resistance R 41 and the output of voltage comparator 51; The emitter of triode Q41 links to each other with the upper end of resistance R 42 and the reverse input end of voltage comparator 51, and the lower end of R42 links to each other with the common ground end, and the input in the same way of voltage comparator 51 links to each other with reference voltage.
In formation shown in Figure 5, the base current of triode Q41 is provided through resistance R 41 by current input terminal, so triode Q41 is able to conducting, and its emitter current resistance R 42 of flowing through, and produce voltage drop at the two ends of R42.Rising along with resistance R 42 ends pressure; When it equals reference voltage V ref; Voltage comparator 51 beginning conductings are shunted the base current of triode Q41, thereby stop the further conducting of triode Q41; The electric current maximum of the feasible resistance R 42 of flowing through is restricted to Vref/r2, plays the effect of constant-current source.Simultaneously, regulate reference voltage V ref and can regulate, thereby realize dimming function the drive current of this constant-current source.Drive current to red, green, blue three-color LED light string carries out independent regulation respectively, then can on the basis of dimming function, further realize the toning function.
Fig. 6 is the example of single channel control switch circuit in Fig. 2, the LED drive unit shown in Figure 3, and a way control switch 60 comprises PMOS FET Q62, clamp diode ZD61, triode Q61, resistance R 61 and R62 and not gate 61.Wherein, The source electrode of FET Q62 links to each other with the negative electrode of clamp diode ZD61 and the top electrode of control switch; The drain electrode of FET Q62 links to each other with the bottom electrode of control switch, and the grid of FET Q62 links to each other the lower ends of the collector electrode of triode Q61 and resistance R 62 with the anode of clamp diode ZD61 and the upper end of resistance R 62; The emitter of triode Q61 links to each other with earth terminal; The base stage of triode Q61 links to each other with the right-hand member of resistance R 61, and the input of not gate 61 links to each other with control signal Vi, and the output of not gate 61 links to each other with the left end of resistance R 61.
In formation shown in Figure 6; When input signal Vi was high level, not gate 61 was output as low level, made triode Q61 end; The electric current of the resistance R of flowing through 62 is 0; Thereby the end of clamp diode ZD61 is pressed and source electrode and the pressure reduction between grid of metal-oxide-semiconductor Q62 are 0, so metal-oxide-semiconductor Q62 ends, is in off-state by the source electrode of metal-oxide-semiconductor Q62 and the control switch that constitutes that drains; In like manner; When input signal Vi was low level, not gate 61 was output as high level, made triode Q61 conducting; Electric current flows through clamp diode ZD61 and produces pressure reduction at its two ends; This pressure reduction also is added between the source electrode and grid of PMOS pipe Q62 simultaneously, so PMOS pipe Q62 is able to conducting, is in conducting state by its source electrode and the control switch that drain electrode constitutes.
Fig. 7 is used to illustrate when control signal is 3 the tunnel, and 3 outputs of counter are by the on off state of the output valve of binary mode and corresponding 3 control switchs and amount to the corresponding relation of lighting/extinguish situation among 7 LED separately.
Shown in (a)~(h) among Fig. 7, the value of counter changes by the mode that increases progressively between 0~7, and its binary coding is respectively 000,001; 010,011,100,101,110 and 111, this encoded radio is through 3 output outputs of counter; These 3 outputs link to each other with corresponding control switch K0, K1, K2 respectively to high-order order according to low level; 1 LED in control switch K0 and the LED lamp string among 7 LED is parallelly connected, and K1 is parallelly connected with 2 LED wherein, and K2 is parallelly connected with 4 remaining LED.
As shown in Figure 7, when the count value of counter was 0, corresponding binary number was 000, and its corresponding 3 outputs are output low level all, so 3 corresponding all conductings of control switch, all 7 LED no current flow through and extinguish, shown in (a) among Fig. 7.When the count value of counter was 5, corresponding binary number was 101, the 0th and the 2nd output high level in its corresponding 3 outputs; And the 1st output low level, so K0 and K2 disconnection in 3 corresponding control switchs, the K1 conducting; Correspondingly; Two LEDs parallelly connected with K1 are caused no current to flow through by short circuit and extinguish, and parallelly connected with K2 4 LED and 1 LED parallelly connected with K0 amount to 5 LED and have electric current to flow through and luminous, shown in (f) among Fig. 7.By that analogy, via the control of control switch, the number of the LED that is lighted in the LED lamp string equates with the count value of counter.
Situation that Fig. 8 describes and the situation of Fig. 7 are similar; Difference is that its coded system is a kind of custom coding mode but not binary mode, and 3 outputs that are used for explaining counter are by the on off state of the output valve of custom coding mode and corresponding 3 control switchs and amount to the corresponding relation that 6 LED lighted/extinguished situation separately.
Shown in (a)~(g) among Fig. 8, the value of counter changes by the mode that increases progressively between 0~6, and its custom coding is respectively 000,001; 010,011,101,110 and 111, this encoded radio is through 3 output outputs of counter; These 3 outputs link to each other with corresponding control switch K0, K1, K2 respectively to high-order order according to low level; In control switch K0 and the LED lamp string among 6 LED 1 is parallelly connected, and K1 is parallelly connected with 2 LED wherein, and K2 is parallelly connected with 3 remaining LED.
As shown in Figure 8, when the count value of counter was 0, correspondence was encoded to 000, and its corresponding 3 outputs are output low level all, so 3 corresponding all conductings of control switch, all 6 LED no current flow through and extinguish, shown in (a) among Fig. 8.When the count value of counter was 5, correspondence was encoded to 110, the 1st and the 2nd output high level in its corresponding 3 outputs; And the 0th output low level, so K1 and K2 disconnection in 3 corresponding control switchs, the K0 conducting; Correspondingly; 1 LED parallelly connected with K0 caused no current to flow through by short circuit and extinguishes, and parallelly connected with K2 3 LED and 2 LEDs parallelly connected with K1 amount to 5 LED and have electric current to flow through and luminous, shown in (f) among Fig. 8.By that analogy, via the control of control switch, the number of the LED that is lighted in the LED lamp string equates with the count value of counter.
Fig. 7 and Fig. 8 are simple in order to explain, have only described the situation of 3 tunnel control signals, will confirm that the LED that connects in the LED lamp string is total according to the height of supply power voltage in the side circuit, and confirm the way and the coded system of required control signal thus.
Ensuing description shows an example of the LED driving method of the utility model, and it may further comprise the steps:
A) adopt the voltage of 11 pairs of external AC power supplies 10 of rectification circuit to carry out rectification;
B) voltage after the rectification provides constant drive current through constant-current source 13 to LED lamp string 12;
C) the two ends pressure reduction with constant-current source 13 adds up through first voltage comparator, 21 triggering forward-backward counters 23;
D) the two ends pressure reduction of constant-current source 13 being triggered forward-backward counters 23 through second voltage comparator 22 tires out and subtracts;
The break-make of the control switch that e) is connected separately by the control of the output of forward-backward counter 23 is participated in luminous LED quantity with adjustment.
Top illustration several kinds of execution modes of the utility model, but the utility model is not limited to illustrative execution mode, the various displacements of illustrative execution mode, distortion is also contained in the scope of the utility model.Provided with those displacements below, be out of shape relevant several examples.
In illustrative execution mode, the control switch in the LED lamp string is not limited to FET, also can be bipolar triode or other switch element.
In illustrative execution mode; The upper voltage limit value Vmax of constant-current source and lower limit Vmin are not limited to certain fixing magnitude of voltage, can combine other implement important document and with magnitude of voltage certain related elements or certain tie point as set Vmax with (or) foundation of Vmin.
In illustrative execution mode; Through break-make control to each control switch; Make and lighted and the luminous LED number of actual participation equates with the count value of counter; And the number of the LED that actual participation is luminous changes by the mode of increasing or decreasing one by one with the count value of counter, but also can be designed to lighted and the luminous LED number of actual participation be counter count value n doubly, correspondingly the number of the each increasing or decreasing of number of the luminous LED of actual participation is n; The quantity of required control signal and control switch is further reduced, thereby it is less to the less demanding occasion of constant-current source two ends pressure reduction to can be used for drive current.
In illustrative execution mode; The producing method of the control signal of switch control unit be not limited to first embodiment illustrative comparator add the mode of counter; Also be not limited to second embodiment illustrative comparator row add the mode of encoder, can also be mode or other circuit form that analog to digital converter adds single-chip microcomputer, it is used for through the two ends pressure reduction that detects constant-current source and adjusts the luminous LED quantity of actual participation thus; When making constant-current source be maintained constant drive current; Its two ends pressure reduction keeps minimum, thereby the power consumption of restriction constant-current source is improved driving efficient.
Rectification circuit is not limited to full-wave rectifying circuit, also can be other rectification circuit such as half-wave rectifying circuit.
Also can use impedance component replacement constant-current sources such as current-limiting resistor, perhaps adopt the current adjusting device of other known structure.
Also can in formation, append overvoltage crowbar,, close drive current, avoid constant-current source to damage because of power consumption is excessive so that cause the end of constant-current source to be pressed when too high in abnormal conditions like Fig. 4, constant-current source shown in Figure 5.
Also can in formation, append temperature-compensation circuit,, prolong the useful life of LED so that when abnormal conditions cause temperature to raise, drive current is limited like Fig. 4, constant-current source shown in Figure 5.
In like Fig. 2, formation shown in Figure 3, use voltage stabilizing didoe directly to obtain low-voltage dc power supply from commutating voltage, also can use voltage stabilizing generation circuit to obtain low-voltage dc power supply by other known structure.
In addition, the various values that illustrate are in the above-described embodiment only pointed out out as an example, and obviously this can suitably set according to implementing important document.
In illustrative execution mode, do not get rid of relevant control circuit such as said low-voltage dc power supply, comparator, counter, control switch and LED lamp string, constant-current source even rectification circuit are integrated in the form in a chip or the encapsulation.
In sum; The LED matrix that the utility model provides; Light through AC power in the LED drive unit of the lamp string that is in series by a plurality of LED; LED lamp string 12 is with after constant-current source 13 is connected, directly parallelly connected with the commutating voltage that after rectification circuit 11 rectifications, is obtained by external AC power supply 10, and the luminous LED quantity of actual participation is between the reference voltage higher limit and lower limit of setting the two ends pressure reduction of constant-current source 13 all the time in the LED lamp string 12 through adjusting simultaneously; And do not receive the influence of LED forward voltage drop discreteness: when the end pressure of constant-current source 13 is higher than the capping value, increases the luminous LED quantity of participation and force down in higher limit until constant-current source 13 ends; When constant-current source 13 ends force down in lower limit, reduce the luminous LED quantity of participation and be higher than lower limit until constant-current source 13 ends pressure.Like this, said LED matrix makes the power consumption of constant-current source 13 obtain restriction, thereby the driving efficient of LED matrix is improved when keeping driving current constant.
Though the utility model discloses as above with preferred embodiment; Right its is not in order to limit the utility model; Any those skilled in the art; In spirit that does not break away from the utility model and scope, when can doing a little modification and perfect, so the protection range of the utility model is when being as the criterion with what claims defined.
Claims (3)
1. LED matrix; Comprise rectification circuit (11), LED lamp string (12), be connected on constant-current source (13) and switch control unit (14) between said rectification circuit (11) and the LED lamp string (12), it is characterized in that, said LED lamp string (12) is divided into the n group; The connection in series-parallel of every group of LED lamp has control switch Ki; Said control switch Ki links to each other with switch control unit (14), and LED lamp number is more than or equal to LED lamp number in the i group in the i+1 group, and i is an integer; N is a natural number, i < n.
2. LED matrix as claimed in claim 1 is characterized in that, said switch control unit (14) comprises first voltage comparator (21), second voltage comparator (22) and forward-backward counter (23); The input of said constant-current source (13) links to each other with the input in the same way of said first voltage comparator (21), the reverse input end of second voltage comparator (22) respectively; The reverse input end input reference upper voltage limit value Vmax of said first voltage comparator (21); The INC end of output and forward-backward counter (23) links to each other; The input reference of the input in the same way lower voltage limit value Vmin of said second voltage comparator (22), the DEC end of output and forward-backward counter (23) links to each other; The output of said forward-backward counter (23) links to each other with control switch successively.
3. according to claim 1 or claim 2 LED matrix is characterized in that, in the said i group in the LED lamp string LED lamp number be 2
i, the value of i is 0,1 ..., n-1.
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CN2011203601844U CN202261969U (en) | 2011-09-23 | 2011-09-23 | LED device |
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CN2011203601844U CN202261969U (en) | 2011-09-23 | 2011-09-23 | LED device |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102287785A (en) * | 2011-09-23 | 2011-12-21 | 付会芬 | Light-emitting diode (LED) device and driving method thereof |
TWI477190B (en) * | 2012-08-10 | 2015-03-11 | Macroblock Inc | Light emitting diode driving apparatus |
TWI496501B (en) * | 2012-08-22 | 2015-08-11 | Macroblock Inc | Piecewise linear driving light source apparatus |
CN107409451A (en) * | 2015-03-09 | 2017-11-28 | 皇家飞利浦有限公司 | LED illumination circuit with controllable LED matrix |
-
2011
- 2011-09-23 CN CN2011203601844U patent/CN202261969U/en not_active Expired - Lifetime
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102287785A (en) * | 2011-09-23 | 2011-12-21 | 付会芬 | Light-emitting diode (LED) device and driving method thereof |
CN102287785B (en) * | 2011-09-23 | 2013-07-24 | 付会芬 | Light-emitting diode (LED) device and driving method thereof |
TWI477190B (en) * | 2012-08-10 | 2015-03-11 | Macroblock Inc | Light emitting diode driving apparatus |
TWI496501B (en) * | 2012-08-22 | 2015-08-11 | Macroblock Inc | Piecewise linear driving light source apparatus |
CN107409451A (en) * | 2015-03-09 | 2017-11-28 | 皇家飞利浦有限公司 | LED illumination circuit with controllable LED matrix |
CN107409451B (en) * | 2015-03-09 | 2020-01-10 | 亮锐控股有限公司 | LED lighting circuit with controllable LED matrix |
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