CN105407587A

CN105407587A - Light emitting element driving circuit

Info

Publication number: CN105407587A
Application number: CN201410462873.4A
Authority: CN
Inventors: 饶东铮; 陈曜洲; 李一惟
Original assignee: Richtek Technology Corp
Current assignee: Richtek Technology Corp
Priority date: 2014-09-12
Filing date: 2014-09-12
Publication date: 2016-03-16
Anticipated expiration: 2034-09-12
Also published as: CN105407587B

Abstract

The invention provides a light emitting element driving circuit for driving a light emitting element circuit which is provided with a plurality of light emitting elements connected in series. The plurality of light emitting elements are divided into a plurality of groups. The light emitting element driving circuit comprises a first switching circuit, a second switching circuit, a current source circuit and a control circuit. The firsts switching circuit comprises a plurality of first switches respectively connected in parallel with the corresponding groups. The second switching circuit comprises a plurality of second switches respectively coupled to forward and reverse ends of a diode circuit, and the second switching circuit decides which one of the forward and reverse ends should be connected to the current source circuit based on the voltage of the forward and reverse ends. The control circuit is used for operating the at least one first switch in the first switching circuit based on an adjustment signal and then deciding which one of the light emitting elements should be conducted.

Description

Light emitting element driving circuit

Technical field

The present invention relates to a kind of light emitting element driving circuit, refer to especially and a kind ofly reduce the light emitting element driving circuit of high-voltage switch number and the driving method of light-emitting element circuit.

Background technology

Figure 1A shows the schematic diagram of a kind of prior art light-emitting diode (lightemittingdiode, LED) drive circuit 10 and interlock circuit thereof.As shown in Figure 1A, LED drive circuit 10 comprise switching circuit 11, ON-OFF control circuit 12, with fixed current source 13.LED drive circuit 10 is in order to driving LED circuit 20, and wherein LED circuit 20 comprises the LED of multiple series connection, and as shown in Figure 1A, the LED of this multiple series connection, is respectively LED1, LED2, LED3 and LED4.Switching circuit 11 comprise switch S 1, S2, S3, with S4 tetra-switches.As shown in Figure 1A, switch S 1-S4 is electrically connected with corresponding LED1-LED4 respectively.AC power 40 produces alternating voltage, and rectification circuit 30 carries out rectification to this alternating voltage, and produces rectified input voltage Vin as shown in Figure 1B.And the basic mode of LED drive circuit 10 driving LED circuit 20, be accurate according to the position of rectified input voltage Vin, the switch S 1-S4 that conducting or not conducting are wherein different, and make the LED1-LED4 in LED circuit 20, wherein one or more LED are luminous.

For example, as signal oscillogram in Figure 1B illustrated, as the accurate L1 accurate lower than position in the position of rectified input voltage Vin, switch S 1-S4 neither conducting, LED1-LED4 is neither luminous; When the position of rectified input voltage Vin is accurate between accurate L1 and the L2 in position, switch S 1 conducting, switch S 2-S4 not conducting, LED1 is luminous; When the position of rectified input voltage Vin is accurate between accurate L2 and the L3 in position, switch S 2 conducting, switch S 1, S3-S4 not conducting, LED1 and LED2 is luminous; When the position of rectified input voltage Vin is accurate between accurate L3 and the L4 in position, switch S 3 conducting, switch S 1-S2, with S4 not conducting, LED1-LED3 is luminous; When the position standard of rectified input voltage Vin exceedes the accurate L4 in position, switch S 4 conducting, switch S 1-S3 not conducting, LED1-LED4 is luminous.Relevant LED drive circuit 10, can with reference to United States Patent (USP) the 6th according to the type of drive of rectified input voltage Vin, 989, No. 807 cases, the 7th, 081, No. 722 cases, with U.S. patent application case No. 2011/0273102 case.

Wherein, fixed current source 13 provides the electric current of fixed size, and during to make that in LED1-LED4, one or more LED is luminous, the electric current flowing through LED is wherein definite value.As electric current I in Figure 1B 1 signal waveform illustrated, when no matter in LED1-LED4, one or more LED is luminous, the electric current flowed through is all fixing, only in the position of rectified input voltage Vin during accurate L1 accurate lower than position, namely switch S 1-S4 neither conducting when, electric current I 1 is zero current.

Compared to the drive circuit of direct voltage drive LED circuit, the advantage of prior art LED drive circuit 10 is not need rectified input voltage Vin to be converted to direct voltage, can save the cost of manufacture; And when the frequency of rectified input voltage Vin is enough high, naked eyes do not see the flicker of LED circuit 20 yet.And one of them shortcoming of prior art LED drive circuit 10 is, each LED needs series connection one can bear high-tension switch, and the size of integrated circuit cannot be reduced; And each switch all needs to arrange a corresponding contact in ON-OFF control circuit 12, this makes the size of ON-OFF control circuit 12 and manufacturing cost to decline.

In view of this, the present invention, namely for above-mentioned the deficiencies in the prior art, proposes a kind ofly to reduce the light emitting element driving circuit of switch and the driving method of light-emitting element circuit.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art and defect, propose a kind ofly to reduce the light emitting element driving circuit of switch and the driving method of light-emitting element circuit.

For reaching above-mentioned purpose, say with regard to one of them viewpoint, the invention provides a kind of light emitting element driving circuit, in order to drive a light-emitting element circuit, wherein this light-emitting element circuit comprises light-emitting component and a diode circuit of multiple series connection, this diode circuit comprises at least one diode or light-emitting diode, the plurality of light-emitting component is connected with this diode in this diode circuit or light-emitting diode, and the plurality of light-emitting component divides into multiple group, each group comprises at least one light-emitting component, this light-emitting element circuit is in order to receive a rectified input voltage, this light emitting element driving circuit comprises: one first switching circuit, comprise multiple first switch, in parallel with the corresponding group in the plurality of group respectively, one second switch circuit, comprises multiple second switch, forward holds respectively couple with a backward end with one of this diode in this diode circuit or light-emitting diode, one current source circuit, couple with this second switch circuit, and provide a light-emitting component electric current to give the light-emitting component of conducting, wherein this second switch circuit forward holds the voltage with this backward end according to this, and determines this forward to be held to be connected with this current source circuit conducting with this backward end whichever, and a control circuit, couple with this first switching circuit, in order to according to an adjustment signal, produce an operation signal, to operate at least one first switch in this first switching circuit, and determine the light-emitting component of conducting.

Wherein in a kind of preferred embodiment, this diode in this diode circuit or light-emitting diode have an identical forward bias voltage drop with this light-emitting component.

Wherein in a kind of preferred embodiment, this adjustment signal is relevant to this and forward holds the voltage with this backward end.

Wherein in a kind of preferred embodiment, this light emitting element driving circuit also comprises an adjustment signal generating circuit, and it comprises: one first comparison circuit, and in order to compare this voltage forward held and a reference signal, produce correspondence one first compares signal; One second comparison circuit, in order to compare voltage and a voltage drop of this backward end, produce correspondence one second compares signal, and wherein this voltage drop is relevant to the voltage that this voltage forward held deducts this backward end; And a counter, first compare signal according to this and second compare signal with this, produce this adjustment signal.

Wherein in a kind of preferred embodiment, this second switch circuit comprises: the plurality of second switch, each this second switch has a second switch electric current and flows into end, a second switch outflow of bus current end and a second switch control end, wherein this second switch electric current flows into end and forward to hold or this backward end couples with this, and this second switch outflow of bus current end and this current source circuit couple; Multiple predetermined current source; Multiple 3rd switch, it has one the 3rd switching current and flows into end, one the 3rd switching current outflow end and one the 3rd switch control terminal, the electric current that this predetermined current source that wherein the 3rd switching current flows into termination receipts correspondence provides also couples with the second switch control end of corresponding second switch, and the 3rd switch control terminal couples with the second switch outflow of bus current end of corresponding second switch; And multiple resistance, couple with the outflow of bus current end of the 3rd corresponding switch respectively.

Wherein in a kind of preferred embodiment, the group that at least one light-emitting component beyond the light-emitting component that this light-emitting element circuit also comprises the plurality of series connection is formed, the light emitting elements in series of this group and the plurality of series connection but in parallel with it without the first corresponding switch.

Wherein in a kind of preferred embodiment, this light emitting element driving circuit, also comprise a sensing circuit, couple with this first switching circuit and/or this second switch circuit, in order to the time point of the pressure drop according to the one or more switches in this first switching circuit and/or this second switch circuit, electric current, conducting or not conducting, produce this adjustment signal.

Wherein in a kind of preferred embodiment, this light emitting element driving circuit, also comprises: a comparison circuit, couples with this rectified input voltage, presets position standard produce comparative result according to rectified input voltage and one; And a timing circuit, couple with this comparison circuit, in order to exceed the time that this default position standard continues according to rectified input voltage, produce this adjustment signal.

Wherein in a kind of preferred embodiment, this light emitting element driving circuit also comprises: a peak value preserves circuit, couples, in order to preserve the voltage peak in the last cycle of this rectified input voltage with this rectified input voltage; And a difference channel, according to the difference of current rectified input voltage and this voltage peak, produce this adjustment signal.

Wherein in a kind of preferred embodiment, in the plurality of group, at least one group is different from the light-emitting component number in another group.

Illustrate in detail below by specific embodiment, when the effect being easier to understand object of the present invention, technology contents, feature and reach.

Accompanying drawing explanation

Figure 1A shows the schematic diagram of a kind of prior art light-emitting diode (lightemittingdiode, LED) drive circuit 10 and interlock circuit thereof;

Figure 1B shows the signal waveform schematic diagram of prior art LED drive circuit 10 and interlock circuit thereof;

Fig. 2 shows first embodiment of the present invention;

Fig. 3 shows second embodiment of the present invention;

Fig. 4 shows the 3rd embodiment of the present invention;

Fig. 5 shows the 4th embodiment of the present invention;

Fig. 6 shows the 5th embodiment of the present invention;

Fig. 7 shows the 6th embodiment of the present invention;

Fig. 8 shows the 7th embodiment of the present invention;

Fig. 9 shows the 8th embodiment of the present invention;

Figure 10 shows the 9th embodiment of the present invention;

Figure 11 shows the of the present invention ten embodiment.

Symbol description in figure

10LED drive circuit

11,110,120 switching circuits

12 ON-OFF control circuit

13 fixed current sources

20LED circuit

21 light-emitting element circuits

30 rectification circuits

40 AC power

100 light emitting element driving circuits

121,125 switches

122,126 resistance

123,124 predetermined current sources

130 current source circuits

140 control circuits

150 sensing circuits

161 comparison circuits

162 timing circuits

171 peak values preserve circuit

172 difference channels

190 adjustment signal generating circuits

191,192 comparison circuits

193 counters

A, A1, B, C, C1 node

COMP1, COMP2 comparative result

D1, D2 diode circuit

G0, G1, G2, Gn group

ILED light-emitting component electric current

I0, I1 electric current

LED1-LED4LED

L1-L4 position is accurate

Q1, Q2 transistor

R1 resistance value

S1-S4, S11, S12, S13, S21, S22, S23 switch

VA, VB voltage

Vin rectified input voltage

Embodiment

Fig. 2 shows first embodiment of the present invention.As shown in Figure 2, light emitting element driving circuit 100 is in order to drive light-emitting element circuit 21, and wherein, light-emitting element circuit 21 comprises light-emitting component and the diode circuit D1 of multiple series connection.The light-emitting component of multiple series connection is connected with diode circuit D1, and multiple light-emitting component divides into multiple group, and such as but not limited to as shown in the figure, be divided into G1, G2 to Gn group, each group comprises at least one light-emitting component.As shown in Figure 2, rectification circuit 30 produces rectified input voltage Vin, and light-emitting element circuit 21 receives rectified input voltage Vin.Light-emitting component is for example and without limitation to LED as shown in the figure.It should be noted that, light-emitting element circuit 21 is not limited to as shown in Figure 2, only comprise single LED strip (and the diode circuit D1 of this LED strip of connecting), light-emitting element circuit 21 can also be the LED array that is made up of the parallel connection of multiple LED strip or the light-emitting component string of other tab sequencial or light-emitting device array etc.In addition, diode circuit D1 comprises at least one diode, and diode is for example and without limitation to the LED with the LED same size of connecting, or has the diode of identical forward bias voltage drop with this light-emitting component.

Please continue to refer to Fig. 2, light emitting element driving circuit 100 comprises switching circuit 110, switching circuit 120, current source circuit 130, control circuit 140 and adjustment signal generating circuit 190.Wherein, switching circuit 110 and light-emitting element circuit 21 couple, and comprise the switch of number corresponding with group G1-Gn in switching circuit 110, in parallel with each group G1-Gn of light-emitting element circuit 21 respectively.Control circuit 140 and switching circuit 110 couple, its adjustment signal produced according to adjustment signal generating circuit 190, produce operation signal, with at least one switch in operation switching circuit 110, and determine the light-emitting component of conducting.The adjustment signal that adjustment signal generating circuit 190 has numerous embodiments to produce, will in rear detailed description.Switching circuit 120 and diode circuit D1 couple, and it is according to the voltage of node A, B, and determine node A, B whichever to be connected with current source circuit 130 conducting.Current source circuit 130 and switching circuit 120 couple, and provide light-emitting component electric current I LED to give the light-emitting component of conducting.

Fig. 3 shows second embodiment of the invention.In the present embodiment, light-emitting element circuit 21 is such as but not limited to group G1, the G2 and the diode circuit D1 that comprise series connection.Wherein, group G1 such as has the LED of 4 series connection, and group G2 such as has the LED of 2 series connection, and diode circuit D1 such as has 1 LED.In switching circuit 110, such as there is switch S 11 and S12, group G1, G2 respectively with corresponding are in parallel, and such as there is in switching circuit 120 switch S 21 and S22, be respectively coupled to (switch S 21 is not shown with the relevant control circuit of S22, illustrates after holding) between node A, B and current source circuit 130.When rectified input voltage Vin is in the stage of rising, its standard, by being enough to conducting LED, rises in the process being enough to conducting seven LED always, and for example, the switch of conducting and group can arrange as follows:

Sequential	The switch of conducting	The group of conducting
			1	S11,S12,S22	D1
2	S11,S21	G2
			3	S11,S22	G2 and D1
4	S12,S21	G1
			5	S12,S22	G1 and D1
6	S21	G1 and G2
			7	S22	G1 and G2 and D1

On the other hand, when rectified input voltage Vin is in the stage declined, its standard is by being enough to conducting seven LED, and drop to can only in the process of a conducting LED always, and for example, switch and conducting group can arrange as follows:

Sequential	The switch of conducting	The group of conducting
			1	S22	G1 and G2 and D1
2	S21	G1 and G2
			3	S12,S22	G1 and D1
4	S12,S21	G1
			5	S11,S22	G2 and D1
6	S11,S21	G2
			7	S11,S12,S22	D1

It should be noted that: because the power with 2 is to arrange the light-emitting component number in each group, all identical compared to the light-emitting component number in each group, significantly can save the number of switch.Certainly, above arrangement is only one preferably execution mode, also can change other arrangement into, still belong to protection scope of the present invention; As long as at least one group is different from the light-emitting component number in another group in multiple group, all identical compared to the light-emitting component number in each group, namely there is the effect of saving number of switches.

Fig. 4 shows the 3rd embodiment of the present invention.In the present embodiment display first and second embodiment aforementioned, switching circuit 120 1 kinds comparatively specific embodiment.As shown in Figure 4, switching circuit 120 comprises multiple switch group, is for example and without limitation to the Liang Ge switch group shown in Fig. 4, is connected to node A and Node B.Switch S 21 in corresponding second embodiment of transistor Q1 and Q2 difference and S22.First switch group, except comprising transistor Q1, also comprises switch 121, resistance 122 and predetermined current source 123; Second switch group, except comprising transistor Q2, also comprises switch 125, resistance 126 and predetermined current source 124.Interelement annexation illustrates for the first switch group comprising transistor Q1: switch 121 is for example and without limitation to transistor as shown in the figure, its electric current flows into end and couples with the control end of transistor Q1, and this electric current flows into hold and receives the electric current (magnitude of current is such as I0) that predetermined current source 123 provides; Outflow of bus current end and the resistance 122 of switch 121 couple.The electric current of transistor Q1 (switch S 21) flows into end and couples with node A, and its outflow of bus current end and current source circuit 130 couple and the control end of control switch 121.The upper end in predetermined current source 123 and 124 can be connected to any suitable current potential.Second switch group is similar to the element connected mode of the first switch group.

For aforementioned second embodiment, the operation mechanism of switching circuit 120 is described, refer to Fig. 4, when the group of conducting such as changes into D1 and G2 by G2, when the LED quantity of namely conducting increases to 3 by 2, the switch of conducting then changes into S11 and S22 by S11 and S21, wherein, in switching circuit 110, the conducting state of switch S 11 is constant, and in switching circuit 120, the switch of conducting becomes S22 from S21.First, when the position of rectified input voltage will definitely conducting 2 LED but when being not enough to conducting 3 LED, because the voltage of node A is enough, first switch group plays a role, but the undertension of Node B, second switch group does not play a role, and therefore switch S 21 is in conducting and switch S 22 is in the state of not conducting.According to the operating principle of circuit, the current potential of the node C1 in Fig. 4, can be equilibrated at I0*R1+Vgs, and wherein, Vgs is the grid-source voltage (switch 121 is for NMOS element) of switch 121; Node C and C2 and node C1 is positioned at same potential, therefore also can be equilibrated at I0*R1+Vgs.

When the current potential of node A rises gradually along with the rising of rectified input voltage Vin, and compared to Node B, when the current potential of node A is increased to the forward bias voltage drop than a Node B also high LED, the LED conducting of group D1, the voltage of Node B is enough, second switch group plays a role, make the current potential of the node C2 in Fig. 4, can I0*2*R1+Vgs be equilibrated at, wherein, I0 is the electric current in predetermined current source 124, and Vgs is the grid-source voltage (switch 125 is for NMOS element) of switch 125; Node C and C1 and node C2 is positioned at same potential, therefore also can be equilibrated at I0*2R1+Vgs.When the potential balance of node C is at I0*2R1+Vgs, the voltage of node A1 can be not enough to actuating switch S21 and make it close.It should be noted that, for convenience of explanation, in the above-described embodiments, flow through the electric current I 0 in predetermined current source 124, such as identical with the electric current I 0 in predetermined current source 123; The grid-source voltage Vgs of switch 125 is such as identical with the grid-source voltage Vgs of switch 121; The resistance value 2*R1 of resistance 126 is such as the twice of the resistance value R1 of resistance 122; But these parameters above-mentioned and multiple all can adjust, as long as when can make switch S 22 conducting, switch S 21 not conducting.For example, the resistance value of resistance 126 can change and is set as R1, and is changed in predetermined current source 124 simultaneously and be set as 2*I0; Or the parameter of change switch 121,125 is as grid-source voltage Vgs; Or multiple can not be twice etc., all belongs to protection scope of the present invention.

On the other hand, when the group of conducting such as changes into G2 by D1 and G2, when the LED quantity of namely conducting is reduced to 2 by 3, the switch of conducting then changes into S11 and S21 by S11 and S22, wherein, when the current potential of node A declines gradually along with the decline of rectified input voltage Vin, and compared to Node B, when the current potential of the node A current potential dropped to lower than Node B adds a LED forward bias voltage drop, LED not conducting in group D1, the undertension of Node B, second switch group does not play a role, the current potential of the node C1 therefore in Fig. 4, can be dropped to by I0*2R1+Vgs and be equilibrated at I0*R1+Vgs.

Fig. 5 shows the 4th embodiment of the present invention.Be with second embodiment difference, the light-emitting element circuit 21 of the present embodiment also comprises group G0, connect, and group G0 is without the switch in parallel of correspondence, and directly receives rectified input voltage Vin with other group G1, G2.The present embodiment is intended to represent according to the present invention, and the group in light-emitting element circuit 21 does not need there is corresponding switch in parallel, as shown in Tu5Zhong group G0, can also not have corresponding switch in parallel.

Fig. 6 shows the 5th embodiment of the present invention.The present embodiment display has the light-emitting element circuit 21 of the LED of a greater number (compared to second embodiment).As shown in the figure, light-emitting element circuit 21 such as but not limited to comprise group G0, the G1 of series connection, G2, G3, with diode circuit D1 and D2.Wherein, group G0 such as has 1 LED, and group G1 such as has the LED of 8 series connection, and group G2 such as has the LED of 4 series connection, and group G3 such as has the LED of 2 series connection, and diode circuit D1 and D2 such as has 1 LED respectively.When rectified input voltage Vin is in the stage of rising, its standard is by being enough to conducting LED, rise in the process being enough to conducting 17 LED, control circuit 140, according to adjustment signal, produces operation signal with switch S 11, S12 and the S13 in control switch circuit 110 always; On the other hand, switching circuit 120 such as respectively else forward holds the current potential with backward end, conducting or not conducting switch S 21, S22 and S23 wherein according in diode circuit D1 and D2.In the present embodiment, in the sequencing control of conducting or not conducting group, by the operation of above-mentioned switch S 11, S12, S13, S21, S22 and S23, in rectified input voltage Vin in the stage of rising, the group of conducting is such as but not limited to being sequentially: G0; G0 and D1; G0, D1 and D2; G0 and G3; G0, G3 and D1; G0, G3, D1 and D2; G0 and G2; G0, G2 and D1; G0, G2, D1 and D2; G0, G2 and G3; G0, G2, G3 and D1; G0, G2, G3, D1 and D2; G0 and G1; G0, G1 and D1; G0, G1, D1 and D2; G0, G1 and G3; G0, G1, G3 and D1; G0, G1, G3, D1 and D2; G0, G1, G2 and G3; G0, G1, G2, G3 and D1; And G0, G1, G2, G3, D1 and D2.On the other hand, when rectified input voltage Vin is in the stage declined, its standard is by being enough to conducting 17 LED, drop to can only in the process of a conducting LED always, in sequential, in the present embodiment, by the operation of above-mentioned switch S 11, S12, S13, S21, S22 and S23, in rectified input voltage Vin in the stage declined, the group of conducting is such as but not limited to the reverse order being sequentially aforementioned sequence.

Be applicable to the switching circuit 120 being applied to Fig. 6 embodiment, such as but not limited to can in Fig. 4 embodiment, increase by one the 3rd switch group (not shown), the component structure of this 3rd switch group is identical with first, second switch group, but the resistance value of its resistance is set as that 3*R1 is (or with reference to aforementioned, change other parameter or multiple), make when the 3rd switch group plays a role, switch S 11, S12 not conducting.

In the embodiment of the 5th shown by Fig. 6, display utilizes a kind of mode of coding, by the light-emitting component permutation and combination in light-emitting element circuit 21, in the process of rectified input voltage Vin rise and fall, increases and the number reducing light-emitting component conducting.Therefore, relative to prior art, according to the present invention, can utilize less number of switches, and control more light-emitting component, this is better than one of them benefit of prior art for the present invention.Especially, directly to be supplied to the framework of light-emitting element circuit without adjustment with rectified input voltage Vin under, needs can operate in the switch (as the S1-S4 of prior art, S11-S13 and the S21-S23 in the embodiment of the present invention etc.) of high voltage environment, and these operate in high-tension switch, in integrated circuit, all occupy larger area, therefore, can reduce according to the present invention and operate in high-tension switch, also reduce the area of integrated circuit, and reduce manufacturing cost.In addition, the switch 121,125 in switching circuit 120 of the present invention does not need to bear big current, and the less transistor unit of size can be used to make; Relatively it, in the prior art, the transistor unit of its ON-OFF control circuit 12 inside must use larger-size transistor unit to make.

Fig. 7 shows the 6th embodiment of the present invention.The present embodiment is intended to explanation, diode circuit D1 and D2, itself and group G0, G1, tandem with G2, be not limited to diode circuit D1 and D2, be serially connected with group G0, G1, with the end of G2, can also as shown in Figure 7, be serially connected with staggered for diode circuit D1 and D2 between group G0, G1 and G2.Group G0 such as has 1 LED, and group G1 such as has the LED of 2 series connection, and group G2 such as has 1 LED, and diode circuit D1 and D2 such as has 1 LED respectively.When rectified input voltage Vin is in the stage of rising, its standard, by being enough to conducting LED, rises in the process being enough to conducting six LED always, and control circuit 140, according to adjustment signal, produces operation signal with the switch S 11 in control switch circuit 110 and S12; On the other hand, switching circuit 120 such as respectively else forward holds the current potential with backward end, conducting or not conducting switch S 21, S22 and S23 wherein according in diode circuit D1 and D2.In the present embodiment, in the sequencing control of conducting or not conducting group, by the operation of above-mentioned switch S 11, S12, S21, S22 and S23, in rectified input voltage Vin in the stage of rising, the group of conducting is such as but not limited to being sequentially: G0; G0 and D1; G0, D1 and D2; G0 and G1; G0, G1 and D1; G0, G1, D1 and D2; G0, G1, D1 and G2; And G0, G1, G2, D1 and D2.On the other hand, when rectified input voltage Vin is in the stage declined, its standard is by being enough to conducting six LED, drop to can only in the process of a conducting LED always, in sequential, in the present embodiment, by the operation of above-mentioned switch S 11, S12, S21, S22 and S23, in rectified input voltage Vin in the stage declined, the group of conducting is such as but not limited to the reverse order being sequentially aforementioned sequence.

Fig. 8 shows the 7th embodiment of the present invention.The present embodiment is intended to the embodiment illustrating adjustment signal generating circuit 190.As shown in Figure 8, in the present embodiment, adjustment signal generating circuit 190 comprises comparison circuit 191 and 192, and counter 193.Comparison circuit 191, according to the voltage VA of node A, compares mutually with reference voltage Vref, produces comparative result COMP1, with enter counter 193.Such as when voltage VA is lower than reference voltage Vref, produce comparative result COMP1, count under being intended to make the number of LED conducting, namely by the control of switching circuit 120, the group of change conducting, makes the LED decreased number one of conducting.On the other hand, comparison circuit 192, according to the voltage VB of Node B, compares mutually with voltage difference VA-VB, produces comparative result COMP2, with enter counter 193.Such as when voltage VB is higher than voltage difference VA-VB, produce comparative result COMP2, with being intended to make the number of LED conducting counts, namely by the control of switching circuit 120, the group of change conducting, makes the LED number of conducting increase by one.By adjustment signal, make the sequencing control of conducting or not conducting group, can carry out as the mode of previous embodiment.

Fig. 9 shows the 8th embodiment of the present invention.The present embodiment is intended to the another kind of execution mode illustrating adjustment signal generating circuit 190.As shown in Figure 9, adjustment signal generating circuit 190 can comprise a sensing circuit 150, couple with switching circuit 110 and/or switching circuit 120, in order to the time point etc. of the pressure drop according to the one or more switches in switching circuit 110 and/or switching circuit 120, electric current, conducting or not conducting, produce adjustment signal.In brief, the pressure drop of switch or electric current all can show the stage of current conducting, and when the frequency of rectified input voltage Vin is known, when control circuit 140 is that is measurable should enter next conducting phase and change the group of conducting.

Figure 10 shows the 9th embodiment of the present invention.The present embodiment is intended to illustrate according to the present invention, again the producing method of another kind of adjustment signal.As shown in Figure 10, adjustment signal generating circuit 190 can comprise comparison circuit 161 and timing circuit 162, comparison circuit 161 and rectified input voltage Vin couple, comparative result is produced according to rectified input voltage Vin and the accurate Vpdl in default position, and timing circuit 162 and comparison circuit 161 couple, in order to exceed the time that the accurate Vpdl in default position continues according to rectified input voltage Vin, produce adjustment signal.Described " coupling with rectified input voltage Vin " is not limited to directly be connected, and also can take from its dividing potential drop or otherwise indirectly connect.

Figure 11 shows the of the present invention ten embodiment.The present embodiment is intended to illustrate according to the present invention, again the producing method of another kind of adjustment signal.As shown in figure 11, adjustment signal generating circuit 190 can comprise peak value and preserve circuit 171 and difference channel 172, peak value is preserved circuit 171 and is coupled with rectified input voltage Vin, in order to preserve the voltage peak in the last cycle of rectified input voltage Vin, the difference of the current rectified input voltage Vin of difference channel 172 bases and this voltage peak produces adjustment signal.

Below for preferred embodiment, the present invention is described, just the above, be only and make those skilled in the art be easy to understand content of the present invention, be not used for limiting interest field of the present invention.Under same spirit of the present invention, those skilled in the art can think and various equivalence change.Such as, two circuit that in each embodiment, icon directly connects or interelement, can plant other circuit or element of not affecting major function, and except the light-emitting component of series connection, also can set up light-emitting component in parallel; And for example, light-emitting component is not limited to the light-emitting diode (LED) shown in each embodiment, also can extend to the light-emitting component with forward end and reverse end; For another example, " one " shown in any embodiment light-emitting component also can change as the light-emitting component of other arbitrary number and along with the rising of rectified input voltage Vin or decline and the number of the light-emitting component of the conducting changed, be not limited to change one (number difference between the stage of front and back is not limited to be necessary for one, and can be other arbitrary number) at every turn.All this kind, all teaching according to the present invention can analogize and obtain, and therefore, protection scope of the present invention should contain above-mentioned and other all equivalence change, and again, arbitrary claim of the present invention must not possess all advantages being better than prior art.

Claims

1. a light emitting element driving circuit, in order to drive a light-emitting element circuit, wherein this light-emitting element circuit comprises light-emitting component and a diode circuit of multiple series connection, this diode circuit comprises at least one diode or light-emitting diode, the plurality of light-emitting component is connected with this diode in this diode circuit or light-emitting diode, and the plurality of light-emitting component divides into multiple group, each group comprises at least one light-emitting component, this light-emitting element circuit is in order to receive a rectified input voltage, it is characterized in that, this light emitting element driving circuit comprises:

One first switching circuit, comprises multiple first switch, in parallel with the corresponding group in the plurality of group respectively;

One second switch circuit, comprises multiple second switch, forward holds respectively couple with a backward end with one of this diode in this diode circuit or light-emitting diode;

One current source circuit, couple with this second switch circuit, and provide a light-emitting component electric current to give the light-emitting component of conducting, wherein this second switch circuit forward holds the voltage with this backward end according to this, and determines this forward to be held to be connected with this current source circuit conducting with this backward end whichever; And

One control circuit, couples with this first switching circuit, in order to according to an adjustment signal, produces an operation signal, to operate at least one first switch in this first switching circuit, and determines the light-emitting component of conducting.

2. light emitting element driving circuit as claimed in claim 1, wherein, this diode in this diode circuit or light-emitting diode have an identical forward bias voltage drop with this light-emitting component.

3. light emitting element driving circuit as claimed in claim 1, wherein, this adjustment signal is relevant to this and forward holds the voltage with this backward end.

4. light emitting element driving circuit as claimed in claim 3, wherein, also comprise an adjustment signal generating circuit, it comprises:

One first comparison circuit, in order to compare this voltage forward held and a reference signal, produce correspondence one first compares signal;

One second comparison circuit, in order to compare voltage and a voltage drop of this backward end, produce correspondence one second compares signal, and wherein this voltage drop is relevant to the voltage that this voltage forward held deducts this backward end; And

One counter, first compares signal according to this and second compares signal with this, produce this adjustment signal.

5. light emitting element driving circuit as claimed in claim 1, wherein, this second switch circuit comprises:

The plurality of second switch, each this second switch has a second switch electric current and flows into end, a second switch outflow of bus current end and a second switch control end, wherein this second switch electric current flows into end and forward to hold or this backward end couples with this, and this second switch outflow of bus current end and this current source circuit couple;

Multiple predetermined current source;

Multiple 3rd switch, it has one the 3rd switching current and flows into end, one the 3rd switching current outflow end and one the 3rd switch control terminal, the electric current that this predetermined current source that wherein the 3rd switching current flows into termination receipts correspondence provides also couples with the second switch control end of corresponding second switch, and the 3rd switch control terminal couples with the second switch outflow of bus current end of corresponding second switch; And

Multiple resistance, couples with the outflow of bus current end of the 3rd corresponding switch respectively.

6. light emitting element driving circuit as claimed in claim 1, wherein, the group that at least one light-emitting component beyond the light-emitting component that this light-emitting element circuit also comprises the plurality of series connection is formed, the light emitting elements in series of this group and the plurality of series connection but in parallel with it without the first corresponding switch.

7. light emitting element driving circuit as claimed in claim 1, wherein, also comprise a sensing circuit, couple with this first switching circuit and/or this second switch circuit, in order to the time point of the pressure drop according to the one or more switches in this first switching circuit and/or this second switch circuit, electric current, conducting or not conducting, produce this adjustment signal.

8. light emitting element driving circuit as claimed in claim 1, wherein, also comprises:

One comparison circuit, couples with this rectified input voltage, presets position standard produce comparative result according to rectified input voltage and one; And

One timing circuit, couples with this comparison circuit, in order to exceed the time that this default position standard continues according to rectified input voltage, produces this adjustment signal.

9. light emitting element driving circuit as claimed in claim 1, wherein, also comprises:

One peak value preserves circuit, couples, in order to preserve the voltage peak in the last cycle of this rectified input voltage with this rectified input voltage; And

One difference channel, according to the difference of current rectified input voltage with this voltage peak, produces this adjustment signal.

10. light emitting element driving circuit as claimed in claim 1, wherein, in the plurality of group, at least one group is different from the light-emitting component number in another group.