CN100395805C - Light-emitting diode driving device - Google Patents
Light-emitting diode driving device Download PDFInfo
- Publication number
- CN100395805C CN100395805C CNB021516421A CN02151642A CN100395805C CN 100395805 C CN100395805 C CN 100395805C CN B021516421 A CNB021516421 A CN B021516421A CN 02151642 A CN02151642 A CN 02151642A CN 100395805 C CN100395805 C CN 100395805C
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- Prior art keywords
- emitting diode
- light emitting
- effect transistor
- field effect
- drive device
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Abstract
The present invention relates to a driving device of a light emitting diode, which comprises at least one light emitting diode, a voltage regulating source, a sawtooth wave generator, a, a field effect transistor, an auxiliary power supply, a current limiting resistor and a resistor. Sawtooth waves generated by the sawtooth wave generator and regulated voltage output by the voltage regulating source are input into the input end of the comparator, and the output end of the comparator is connected to a grid electrode of the field effect transistor. After connected with the current limiting resistor, the auxiliary power supply is connected to a source electrode of the field effect transistor, and a drain electrode of the field effect transistor outputs driving current to the light emitting diode through the resistor.
Description
[technical field]
The present invention relates to a kind of light emitting diode drive device, refer in particular to a kind of pulse-width modulation type light emitting diode drive device.
[background technology]
In the prior art, the driving of light emitting diode is with a voltage source directly driven for emitting lights diode of connecting behind the current-limiting resistance, because being forward bias voltage drop, light emitting diode drives, its cross-pressure can be different because of drive current, therefore when linear adjustment driving voltage is big or small, the change of drive current can influence the cross-pressure of light emitting diode, makes drive current can not make linear change in company with voltage source.Even when voltage source changes too greatly,, can burn light emitting diode because forward bias voltage drop is excessive.
Consult Fig. 1, it is a kind of light emitting diode drive device in the prior art, wherein voltage source 10 applies a voltage on the light emitting diode matrix 30 by current-limiting resistance 20, this light emitting diode matrix 30 comprises the capable n row of a m light emitting diode 31, the resistance of this current-limiting resistance 20 is R, the voltage of voltage source 10 is U, and the main line electric current is I, and the equivalent resistance of single light emitting diode 31 is R
S
Please consulting Fig. 2 together, is the forward volt-ampere characteristics of figure of light emitting diode 31, and the model of its volt-ampere characteristic can be represented by the formula:
V
F＝V
on+R
S?I
F+(ΔV
F/ΔT)(T-25℃)
Wherein, Von is the trigger voltage of light emitting diode 31, R
SBe the equivalent resistance of light emitting diode 31, T is an environment temperature, Δ V
F/ Δ T is the temperature coefficient of light emitting diode forward voltage, and representative value is-2V/ ℃ for most light emitting diodes.Under the constant situation of environment temperature, model simplification is:
V
F＝V
on+R
S?I
F
So the volt-ampere characteristic of existing light emitting diode drive device shown in Figure 1 can be represented by the formula:
U-m*V
on＝I(R+R
S(m/n))
This formula is reduced to:
U-V
X=I (R+R
X) wherein, V
X=m*V
On, R
X=R
S(m/n)
Because the existence of the trigger voltage Von of light emitting diode 31, electric current I is the linear change with the change of voltage U not as can be known, and when becoming original two times when voltage U, the electric current I variation is less than original two times.Therefore, also can not be when driving voltage changes linearly change drive current and make the light output of light emitting diode do the variation of corresponding linearity even drive fixing light emitting diode matrix.So be difficult to finish accurate control to the light output of light emitting diode.
And when the light emitting diode matrix that drives not be when immobilizing, when promptly its array format or light emitting diode number change, i.e. V
XAnd R
XWhen changing,, often need driving voltage U and current-limiting resistance R are adjusted, equally also can't when driving voltage changes, make the light of light emitting diode export the variation of making corresponding linearity for satisfying suitable light emitting diode electrical installation environment.When the application that is used for load variations, a lot of inconvenience are arranged, equally also be difficult to finish accurate control the light output of light emitting diode.
[summary of the invention]
For overcoming the defective of the light output that is difficult to accurately to control light emitting diode in the prior art, the invention provides a kind of can be simply and the accurate light emitting diode drive device of the light output of control light emitting diode.
The technical scheme of technical solution problem of the present invention is: a kind of light emitting diode drive device is provided, and it comprises at least one light emitting diode, an adjustment voltage source, a saw-toothed wave generator, a comparer, a field effect transistor, an accessory power supply, a current-limiting resistance and a resistance.The adjustment voltage of sawtooth wave that saw-toothed wave generator produces and the output of adjustment voltage source inputs to the input end of comparer, the output terminal of comparer is connected to the grid of field effect transistor, accessory power supply connects the source electrode that is connected to field effect transistor behind the current-limiting resistance, to light emitting diode, this saw-toothed wave generator, comparer and adjustment voltage source constitute the square wave signal generator of a dutycycle with the adjustment voltage forward linear change of adjusting voltage source output by the resistance output driving current in the drain electrode of field effect transistor.
Compare with prior art, the advantage of light emitting diode drive device of the present invention is that it adopts pulse width modulation mode driven for emitting lights diode, can linear adjust the drive current of light emitting diode and accurately control the light output of light emitting diode, and when the application that is used for load variations, also can linear adjust the drive current of light emitting diode and accurately control the light output of light emitting diode.
[description of drawings]
Fig. 1 is the synoptic diagram of light emitting diode drive device in the prior art.
Fig. 2 is the volt-ampere characteristics of figure of light emitting diode.
Fig. 3 is the synoptic diagram of light emitting diode drive device of the present invention.
Fig. 4 is the oscillogram of light emitting diode drive device of the present invention.
Fig. 5 is the oscillogram of the comparer in the light emitting diode drive device of the present invention.
[embodiment]
See also Fig. 3, light emitting diode drive device of the present invention comprises a saw-toothed wave generator 1, an adjustment voltage source 6, a comparer 2, a n channel enhancement type field effect transistor 3, an accessory power supply 7, a current-limiting resistance 4 and a resistance 5.The output terminal of saw-toothed wave generator 1 is connected to an input end of comparer 2, another input end of comparer 2 is connected to adjusts voltage source 6, the output terminal of comparer 2 is connected to the grid of field effect transistor 3, current-limiting resistance 4 two ends are connected to the source electrode of accessory power supply 7 and field effect transistor 3, the drain electrode connecting resistance 5 rear drive light emitting diode matrixs 8 of field effect transistor 3.
Please consult Fig. 4 together, Vi1 is for adjusting voltage, and Vr1 is a sawtooth signal, and Vo1 is n channel enhancement type field effect transistor 3 grid voltages, and Io1 is the output current of n channel enhancement type field effect transistor 3 drain electrodes.Sawtooth signal Vr1 that saw-toothed wave generator 1 produces and the adjustment voltage Vi1 that adjusts voltage source 6 outputs compare by comparer 2, and when adjusting voltage Vi1 greater than sawtooth signal Vr1 transient voltage, comparer 2 just is output as; When adjusting voltage Vi1 less than sawtooth signal Vr1 transient voltage, comparer 2 is output as zero.This output Vo1 imports from n channel enhancement type field effect transistor 3 grids, accessory power supply 7 connects current-limiting resistance 4 after-applied voltages in the source electrode of n channel enhancement type field effect transistor 3, and the resistance 5 output driving current Io1 that the drain electrode of n channel enhancement type field effect transistor 3 is passed through to be connect are to light emitting diode matrix 8.
See also Fig. 5, adjust the output waveform of comparer under the voltage in difference, Vi1 is an adjustment voltage signal, Vi2 adjusts voltage signal for another, Vr1 is a sawtooth signal, and Vo is the voltage of comparer output high level, the comparer output high level width when t1 is Vi1 for adjusting voltage signal, comparer output high level width when t2 is Vi2 for adjusting voltage signal, T is a sawtooth period.Because of the slope of sawtooth signal is a certain value, thus obvious when Vi2=K Vi1, t2=K t1, (K is for adjusting the ratio of change in voltage).Be that comparer 2 output signals are that a dutycycle is with the square-wave signal of adjusting voltage forward linear change, also be that dutycycle increases along with the increase of adjusting voltage, reduce along with adjusting reducing of voltage (as Fig. 4 and shown in Figure 5), it puts on n channel enhancement type field effect transistor 3 grids, then the drain electrode of n channel enhancement type field effect transistor 3 is exported a fixed current in grid voltage during for high level, and this is the ON state; No-output electric current when grid voltage is zero, this is the OFF state, Io1 is the generation repeatedly of this two-state.The frequency of its ON-OFF is the sawtooth wave frequency, when frequency greatly to the frequency that can respond above system more than 10 times the time, its effect is the driving that light emitting diode matrix 8 is accepted certain electric current, the dutycycle of this size of current and comparer 2 output square-wave signals is linear, and the dutycycle of this square-wave signal is the positive line sexual intercourse with adjustment voltage, so can reach the adjustable driving purposes of light-emitting diodes pipeline by changing adjustment voltage.
If adjust voltage greater than the maximal value of sawtooth signal or less than the minimum value of sawtooth signal, then according to the difference of circuit requirement, perhaps still with comparer relatively and output signal, perhaps increase auxiliary circuit and do other action.The processing of this situation, difference as required and do corresponding variation.
Above-mentioned n channel enhancement type field effect transistor can be replaced by P-channel enhancement type field effect transistor, N channel depletion type field effect transistor, P channel depletion type field effect transistor.
The light source that the light emitting diode matrix that light emitting diode drive device of the present invention and it are driven constitutes can be used as display and other as vehicle, boats and ships, and the light source of the display device of usefulness such as aircraft.
Claims (8)
1. light emitting diode drive device, comprise at least one light emitting diode, it is characterized in that: comprise that also one adjusts voltage source, one saw-toothed wave generator, one comparer, one field effect transistor, one accessory power supply, one current-limiting resistance and another resistance, wherein, the adjustment voltage of sawtooth wave that saw-toothed wave generator produces and the output of adjustment voltage source inputs to the input end of comparer, the output terminal of comparer is connected to the grid of field effect transistor, accessory power supply connects the source electrode that is connected to field effect transistor behind the current-limiting resistance, the drain electrode of field effect transistor connects another resistance and output driving current to light emitting diode, this saw-toothed wave generator, comparer and adjustment voltage source constitute the square wave signal generator of a dutycycle with the adjustment voltage forward linear change of adjusting voltage source output.
2. light emitting diode drive device as claimed in claim 1 is characterized in that this at least one light emitting diode is a light emitting diode matrix.
3. light emitting diode drive device as claimed in claim 1 is characterized in that this field effect transistor is an enhancement mode field effect transistor.
4. light emitting diode drive device as claimed in claim 3 is characterized in that this enhancement mode field effect transistor is the N channel-type.
5. light emitting diode drive device as claimed in claim 3 is characterized in that this enhancement mode field effect transistor is the P channel-type.
6. light emitting diode drive device as claimed in claim 1 is characterized in that this field effect transistor is a depletion mode fet.
7. light emitting diode drive device as claimed in claim 6 is characterized in that this depletion mode fet is the N channel-type.
8. light emitting diode drive device as claimed in claim 6 is characterized in that this depletion mode fet is the P channel-type.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021516421A CN100395805C (en) | 2002-12-28 | 2002-12-28 | Light-emitting diode driving device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021516421A CN100395805C (en) | 2002-12-28 | 2002-12-28 | Light-emitting diode driving device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1512472A CN1512472A (en) | 2004-07-14 |
| CN100395805C true CN100395805C (en) | 2008-06-18 |
Family
ID=34234462
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB021516421A Expired - Fee Related CN100395805C (en) | 2002-12-28 | 2002-12-28 | Light-emitting diode driving device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100395805C (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102073575A (en) * | 2009-11-20 | 2011-05-25 | 鸿富锦精密工业（深圳）有限公司 | Management engine state detection circuit |
| CN101964172B (en) * | 2010-08-18 | 2012-10-03 | 金峰 | LED control circuit |
| CN102802313B (en) * | 2012-08-15 | 2014-09-17 | 无锡华润矽科微电子有限公司 | Method for controlling LED (Light-Emitting Diode) breathing lamp |
| JP2015152699A (en) * | 2014-02-13 | 2015-08-24 | ソニー株式会社 | Light emitting element-driving circuit, display device, and a-d conversion circuit |
| US10523183B2 (en) * | 2018-01-31 | 2019-12-31 | Taiwan Semiconductor Manufacturing Co., Ltd. | Dynamic high voltage (HV) level shifter with temperature compensation for high-side gate driver |
| CN108648690B (en) * | 2018-04-26 | 2020-04-17 | 上海天马有机发光显示技术有限公司 | Display panel and display device |
| CN109523968B (en) * | 2018-12-24 | 2021-02-19 | 惠科股份有限公司 | Control circuit and display device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1111042A (en) * | 1994-01-10 | 1995-11-01 | 皮维电子有限公司 | Multi-stage solid stage amplifier that emulates tube distortion |
| CN1120712A (en) * | 1995-09-28 | 1996-04-17 | 武强 | high brightness large LED display screen and its driving method |
| US5604759A (en) * | 1992-01-30 | 1997-02-18 | Fujitsu Limited | Drive circuit for electronic device |
| US6060943A (en) * | 1998-04-14 | 2000-05-09 | Nmb (Usa) Inc. | Circuit simulating a diode |
-
2002
- 2002-12-28 CN CNB021516421A patent/CN100395805C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5604759A (en) * | 1992-01-30 | 1997-02-18 | Fujitsu Limited | Drive circuit for electronic device |
| CN1111042A (en) * | 1994-01-10 | 1995-11-01 | 皮维电子有限公司 | Multi-stage solid stage amplifier that emulates tube distortion |
| CN1120712A (en) * | 1995-09-28 | 1996-04-17 | 武强 | high brightness large LED display screen and its driving method |
| US6060943A (en) * | 1998-04-14 | 2000-05-09 | Nmb (Usa) Inc. | Circuit simulating a diode |
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| Publication number | Publication date |
|---|---|
| CN1512472A (en) | 2004-07-14 |
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Granted publication date: 20080618 Termination date: 20171228 |