CN101179883A - Light modulation method of LED - Google Patents
Light modulation method of LED Download PDFInfo
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- CN101179883A CN101179883A CNA2006101528867A CN200610152886A CN101179883A CN 101179883 A CN101179883 A CN 101179883A CN A2006101528867 A CNA2006101528867 A CN A2006101528867A CN 200610152886 A CN200610152886 A CN 200610152886A CN 101179883 A CN101179883 A CN 101179883A
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- light
- emitting diode
- dimming method
- control signal
- width modulation
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Abstract
The invention discloses a light-regulating method of a light emitting diode. The light-regulating method of the LED is applied to a pulse-width modulation pressure-boosting system which includes the following steps: (a) a cycle is divided equally into a plurality of intervals;(b) a control signal with a plurality of the cycles and a pulse duration is supplied, wherein, the pulse duration of every control signal is produced orderly in the cycles, and (c) a plurality of the control signals are used to control a corresponding plurality of switches to regulate the light of the light emitting diodes which are connected with the switches.
Description
Technical field
The present invention relates to a kind of light-dimming method of light-emitting diode, relate in particular to a kind of light-dimming method that is applied to the light-emitting diode of a Width pulse modulation booster system (pulse width modulation boost circuit).
Background technology
Fig. 1 is the circuit diagram of a dimming light-emitting diode system 10 of routine.It comprises the switch group 18 and that light-emitting diode group 17, that a booster circuit 11, a PDM keyer 12, a comparator 13, a feedback signal selector 14, a DPWM signal generator 15, comprise 6 LED 1～LED6 comprises 6 switch T1～T6 and comprises 6 current source I
S1～I
S6Current source group 19.Described booster circuit 11 contains a voltage source V
IN, an input capacitance C1, an output capacitance C2, a diode D, a boost inductance L, a resistance R and a switch.The pulse-width signal S that described booster circuit 11 is accepted from described PDM keyer 12
G(having a variable work period (duty cycle)) is with control output voltage V
OUTDescribed PDM keyer 12 is then according to current feedback signal I
SENAnd the output signal of described comparator 13 is in time to adjust described pulse-width signal S
GWork period.The control signal DS that described DPWM signal generator 15 produces
GThen be sent to each the switch T1～T6 in the described switch group 18, with the conducting of controlling described switch T1～T6 simultaneously or close.In general, the forward voltage of white light emitting diode and operating current are respectively 3.6V and 20mA.And sacrifice its reliability (and then quicken white light emitting diode aging) for fear of the maximum current specification of violating white light emitting diode and obtain the brightness and the colourity of measurable and mutual coupling, general white light emitting diode all uses the mode of constant current source to drive.Therefore, the current source I in the described current source group 19
S1～I
S6Connect the LED 1～LED6 in the described light-emitting diode group 17 respectively via switch T1～T6, with the electric current of control flows through LED 1～LED6.Described feedback signal selector 14 receives the feedback signal FB1～FB6 relevant with LED 1～LED6, and select one of them (for example having minimum voltage), to be resent to a described comparator 13 and a reference voltage V among self feed back signal FB1～FB6 as output signal FB0
REFCompare, and then control the work period of described pulse-width signal SG.The brightness of described LED 1～LED6 (brightness) is then by control signal DS
GControl.
Fig. 2 display control signal DS
G, described booster circuit 11 output current I
OUTAnd output voltage V
OUTSequential chart.Control signal DS wherein
GHave an one-period T and a pulse duration P (promptly being in the time of logic high), described pulse duration P in order to while actuating switch T1～T6 make each LED 1～LED6 all flow through an operating current (for example: 20mA) and luminous, this moment described booster circuit 11 output current I
OUTBe 120mA (being 20mA * 6).Adjust control signal DS and utilize
GWork period (promptly adjusting the length of its pulse duration P), then can adjust the brightness of described LED 1～LED6.
The light-dimming method that so is applied to conventional dimming light-emitting diode system 10 but has following shortcoming: (1) is because to the output capacitance C2 charging and the discharge of described booster circuit 11, so that produce excessive ripple voltage (ripple voltage), thereby reduced the service efficiency of power supply; (2) light-dimming method of described booster circuit 11 is with its output current I
OUTIn the switching and according to described control signal DS down of standard-sized sheet (current value 120mA) or complete shut-down (current value is zero) two states
GTime of adjusting whole switch T1～T6 conducting or closing work period (being the ratio of P/T), but not operate in continuous conduction mode (continuousconduction mode; CCM).So method of operation has also reduced the service efficiency of power supply.
Summary of the invention
One aspect of the present invention provides a kind of light-dimming method of light-emitting diode, it is applied to a pulse width modulation boost circuit, control its corresponding light-emitting diode independently by a plurality of control signals that produce in regular turn, with the ripple voltage of the output voltage that reduces described pulse width modulation boost circuit, and improve the power supply service efficiency of described pulse width modulation boost circuit.
The present invention provides the light-dimming method of a light-emitting diode on the other hand, it is applied to a pulse width modulation boost circuit, control its corresponding light-emitting diode independently by a plurality of control signals that produce in regular turn, make described pulse width modulation boost circuit operate in continuous conduction mode, to improve the power supply service efficiency of described pulse width modulation boost circuit.
The present invention discloses a kind of light-dimming method of light-emitting diode, is applied in a pulse width modulation boost circuit, and described light-dimming method comprises following steps: (a) will be divided into a plurality of intervals one-period; (b) provide a plurality of and have the described cycle and have the control signal in a pulse duration, wherein the pulse duration of each control signal results from the described cycle in regular turn; And (c) utilize described a plurality of control signal to control a plurality of corresponding switches, to carry out light modulation for the light-emitting diode that is connected in each switch.
Description of drawings
Fig. 1 is a conventional dimming light-emitting diode circuit system schematic diagram;
Fig. 2 is the signal timing diagram relevant with Fig. 1;
Fig. 3 is the circuit diagram of the dimming light-emitting diode system of one embodiment of the invention;
Fig. 4 is the control signal sequential chart relevant with Fig. 3; And
Fig. 5 (a)～5 (c) is at different control signal signal timing diagram relevant with Fig. 3 under the work period.
Embodiment
Fig. 3 is the circuit diagram of the dimming light-emitting diode system 20 of dimming light-emitting diode method one embodiment of the present invention.Described light adjusting system 20 comprises: the switch group 28 and that the light-emitting diode group 27, that a booster circuit 21, a PDM keyer 22, a comparator 23, a feedback signal selector 24, a DPWM signal generator 25, comprise 6 light-emitting diodes (figure do not show) comprises 6 switch T1～T6 (in the present embodiment with MOS transistor as switch) comprises 6 current sources current source group 29 of (figure does not show).The operating principle of described light adjusting system 20 is described below.The pulse-width signal S ' that described booster circuit 21 is accepted from described PDM keyer 22
G(having a variable work period) is with control output voltage V '
OUTDescribed PDM keyer 22 is then according to current feedback signal I '
SENAnd the output signal of described comparator 23 is in time to adjust described pulse-width signal S '
GWork period.6 control signal DP1～DP6 that described DPWM signal generator 25 produces are sent to the grid g1～g6 of each the switch T1～T6 in the described switch group 28 respectively, with the conducting of controlling described switch T1～T6 in regular turn or close.6 current sources in the described current source group 29 connect 6 light-emitting diodes (its connected mode is identical with Fig. 1) in the described light-emitting diode group 27 respectively via switch T1～T6, with the electric current of control flows through described 6 light-emitting diodes.Described feedback signal selector 24 receives and the relevant feedback signal FB1 '～FB6 ' of described 6 light-emitting diodes, and self feed back signal FB1 '～middle selection of FB6 ' one of them (for example having minimum voltage) as output signal FB0 ', is resent to a described comparator 23 and a reference voltage V '
REFCompare, and then control described pulse-width signal S '
GWork period.The brightness of described 6 light-emitting diodes is then controlled by control signal DP1～DP6.
Fig. 4 is control signal DP1～DP6 sequential chart of light-dimming method one embodiment of light-emitting diode of the present invention.One clock signal with one-period T ' at first is provided.Then with 6 interval Ph1～Ph6 of described period T ' be divided into.Afterwards, provide 6 control signal DP1～DP6 by described DPWM signal generator 25, it all has identical described period T ' and respectively have a pulse duration P1～P6 (described 6 pulse duration P1～P6 all equate) in the present embodiment.Described 6 pulse duration P1～P6 betide described period T ' interior in regular turn and are sent to grid g1～g6 of described 6 switch T1～T6 respectively.Therefore described 6 pulse duration P1～P6 promptly correspond to the operating current I1～I6 of described 6 light-emitting diodes of flowing through.In addition, described 6 control signal DP1～DP6 can produce by a described clock signal (cycle is T ') and a time delay circuit (time-delay circuit).Notice that in the present embodiment, described 6 control signal DP1～DP6 all have the identical work period, i.e. P1/T ' is to call the control signal work period in the following text.
Fig. 5 (a)～5 (c) is at the operating current I1～I6 of different control signals under the work period, the output current I ' of described booster circuit 21
OUTAnd output voltage V '
OUTSequential chart.With reference to figure 5 (a), wherein the control signal work period is less than 1/6 (about 1/2).Each operating current I1～I6 occur in regular turn described period T ' in, and size is equal to separately operating current (being 20mA).Fig. 5 (a) is though the described booster circuit 21 under the situation operates in discontinuous conduction mode (discontinuous conductionmode; DCM), however by increasing output current I '
OUTFrequency, can be so that output voltage V '
OUTRipple voltage reduce, to reduce because of described output capacitance C2 (ginseng Fig. 1) being discharged and recharged the energy of loss.Comparison diagram 5 (a) and Fig. 2, as can be known output voltage V among Fig. 5 (a) '
OUTRipple voltage be significantly less than output voltage V among Fig. 2 '
OUTRipple voltage, and the former frequency is 6 times of the latter.The identical work period (for example: 10%), (6 * 10% * 20mA) equate (10% * 120mA) with average output current shown in Figure 2 to average output current shown in Fig. 5 (a), yet, as indicated above, because of the output voltage of Fig. 5 (a) has less ripple voltage, so can improve the power supply service efficiency of described booster circuit 21.
With reference to figure 5 (b), wherein the control signal work period equals 1/6.Each operating current I1～I6 occur in regular turn described period T ' in, and size is equal to separately operating current (being 20mA).Described booster circuit 21 under Fig. 5 (b) situation operates in continuous conduction mode, and its output current I ' OUT is continuously output, and size is 20mA.
Fig. 5 (c) then is the situation of control signal work period greater than 1/6 (being about 1/3).Each operating current I1～I6 occur in regular turn described period T ' in, and size is equal to separately operating current (being 20mA).Described booster circuit 21 under Fig. 5 (c) situation operates in continuous conduction mode, and its output current I '
OUTBe continuous output, size is 40mA; In other words, when the control signal work period greater than 1/6 the time, output current I ' then
OUTWill be greater than the operating current (being 20mA) of light-emitting diode.Under the situation of Fig. 5 (b) and 5 (c), output voltage V '
OUTSignificantly ripple-free voltage produce and be equal to light-emitting diode forward voltage (for example: 3.6V)
The above embodiments are to be example explanation with 6 light-emitting diodes, also can implement yet dimming light-emitting diode method of the present invention is not limited to the number of light-emitting diode.Compare with the conventional light-dimming method of Fig. 2, the present invention is divided into a plurality of intervals with the cycle of a clock pulse signal, and provide a plurality of control signals in corresponding described a plurality of intervals, make the pulse duration of every described control signal betide at least one described a plurality of intervals, promptly making all has output current to produce in each interval, with the ripple voltage that reduces output voltage or booster circuit is operated under the continuous conduction mode, so dimming light-emitting diode method of the present invention can be improved the power supply service efficiency of pulse width modulation boost circuit really.
Technology contents of the present invention and technical characterstic disclose as above, yet the those skilled in the art still may be based on teaching of the present invention and announcement and done all replacement and modifications that does not break away from spirit of the present invention.Therefore, protection scope of the present invention should be not limited to the content that embodiment discloses, and should comprise various do not break away from replacement of the present invention and modifications, and is contained by appending claims.
Claims (16)
1. the light-dimming method of a light-emitting diode is applied to a pulse width modulation boost circuit, it is characterized in that described light-dimming method comprises following steps:
To be divided into a plurality of intervals one-period;
Provide a plurality of and have the described cycle and have the control signal in a pulse duration, wherein the pulse duration of each control signal results from the described cycle in regular turn; And
Utilize described a plurality of control signal to control a plurality of corresponding switches, to carry out light modulation for the light-emitting diode that is connected in each switch.
2. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that described pulse width modulation boost circuit operates in a discontinuous conduction mode.
3. the light-dimming method of light-emitting diode as claimed in claim 2 is characterized in that the described lasting burst length is less than described interval.
4. the light-dimming method of light-emitting diode as claimed in claim 3 is characterized in that electric current flows through time of each light-emitting diode less than described interval.
5. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that described pulse width modulation boost circuit operates in a continuous conduction mode.
6. the light-dimming method of light-emitting diode as claimed in claim 5 is characterized in that the described lasting burst length is more than or equal to described interval.
7. the light-dimming method of light-emitting diode as claimed in claim 5 is characterized in that the output voltage ripple-free voltage of described pulse width modulation boost circuit produces.
8. the light-dimming method of light-emitting diode as claimed in claim 6, it is characterized in that when the described lasting burst length greater than described when interval, the output current of described pulse width modulation boost circuit in the described cycle greater than the operating current of described light-emitting diode.
9. the light-dimming method of light-emitting diode as claimed in claim 5 is characterized in that the output voltage of described pulse width modulation boost circuit equals the forward voltage of described light-emitting diode in the described cycle.
10. the light-dimming method of light-emitting diode as claimed in claim 5 is characterized in that described pulse width modulation boost circuit is at the equal output current in every described a plurality of intervals.
11. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that every described pulse duration all equates.
12. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that described a plurality of control signal produces by a clock signal with described cycle.
13. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that described a plurality of control signal utilizes a time delay circuit and produce.
14. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that described pulse width modulation boost circuit is a current mode width pulse modulation booster circuit.
15. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that the number in described interval equals the number of described control signal.
16. the light-dimming method of light-emitting diode as claimed in claim 1 is characterized in that described switch is a MOS transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101528867A CN100553393C (en) | 2006-11-06 | 2006-11-06 | The light-dimming method of light-emitting diode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101528867A CN100553393C (en) | 2006-11-06 | 2006-11-06 | The light-dimming method of light-emitting diode |
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| Publication Number | Publication Date |
|---|---|
| CN101179883A true CN101179883A (en) | 2008-05-14 |
| CN100553393C CN100553393C (en) | 2009-10-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2006101528867A Expired - Fee Related CN100553393C (en) | 2006-11-06 | 2006-11-06 | The light-dimming method of light-emitting diode |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101965075A (en) * | 2009-07-22 | 2011-02-02 | 台达电子工业股份有限公司 | Power supply circuit and control method thereof |
| CN102131326A (en) * | 2010-01-16 | 2011-07-20 | 杨义根 | Power supply mode and device of multipath light emitting diodes (LED) |
| CN102316648A (en) * | 2011-09-15 | 2012-01-11 | 四川新力光源有限公司 | Light-emitting diode (LED) illuminating device |
| CN102413600A (en) * | 2010-09-25 | 2012-04-11 | 台达电子工业股份有限公司 | Luminous device and control method thereof |
| CN101588664B (en) * | 2008-05-21 | 2012-12-05 | 原景科技股份有限公司 | Light emitting diode drive circuit and circuit for controlling power switch |
| US8427081B2 (en) | 2009-09-16 | 2013-04-23 | Novatek Microelectronics Corp. | Driving apparatus of light emitting diode and driving method thereof |
| CN103957643A (en) * | 2009-09-23 | 2014-07-30 | 联咏科技股份有限公司 | Driving device of light emitting diode and driving method thereof |
| CN102026439B (en) * | 2009-09-23 | 2014-11-05 | 联咏科技股份有限公司 | Driving device and driving method for light emitting diode |
-
2006
- 2006-11-06 CN CNB2006101528867A patent/CN100553393C/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101588664B (en) * | 2008-05-21 | 2012-12-05 | 原景科技股份有限公司 | Light emitting diode drive circuit and circuit for controlling power switch |
| CN101965075A (en) * | 2009-07-22 | 2011-02-02 | 台达电子工业股份有限公司 | Power supply circuit and control method thereof |
| US8427081B2 (en) | 2009-09-16 | 2013-04-23 | Novatek Microelectronics Corp. | Driving apparatus of light emitting diode and driving method thereof |
| USRE46330E1 (en) | 2009-09-16 | 2017-02-28 | Novatek Microelectronics Corp. | Driving apparatus of light emitting diode and driving method thereof |
| CN103957643A (en) * | 2009-09-23 | 2014-07-30 | 联咏科技股份有限公司 | Driving device of light emitting diode and driving method thereof |
| CN102026439B (en) * | 2009-09-23 | 2014-11-05 | 联咏科技股份有限公司 | Driving device and driving method for light emitting diode |
| CN102131326A (en) * | 2010-01-16 | 2011-07-20 | 杨义根 | Power supply mode and device of multipath light emitting diodes (LED) |
| CN102413600A (en) * | 2010-09-25 | 2012-04-11 | 台达电子工业股份有限公司 | Luminous device and control method thereof |
| CN102413600B (en) * | 2010-09-25 | 2014-08-20 | 台达电子工业股份有限公司 | Luminous device and control method thereof |
| CN102316648A (en) * | 2011-09-15 | 2012-01-11 | 四川新力光源有限公司 | Light-emitting diode (LED) illuminating device |
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| Publication number | Publication date |
|---|---|
| CN100553393C (en) | 2009-10-21 |
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Granted publication date: 20091021 Termination date: 20171106 |