CN101473456B - Light emitting diode driving circuit - Google Patents
Light emitting diode driving circuit Download PDFInfo
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- CN101473456B CN101473456B CN2007800224763A CN200780022476A CN101473456B CN 101473456 B CN101473456 B CN 101473456B CN 2007800224763 A CN2007800224763 A CN 2007800224763A CN 200780022476 A CN200780022476 A CN 200780022476A CN 101473456 B CN101473456 B CN 101473456B
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- 230000015572 biosynthetic process Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 206010070834 Sensitisation Diseases 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 108091008695 photoreceptors Proteins 0.000 description 1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
- H05B45/14—Controlling the intensity of the light using electrical feedback from LEDs or from LED modules
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- Control Of El Displays (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
The invention provides a light emitting diode driving circuit which can adjust the light emitting brightness of a light emitting diode with high precision and can restrain the increase of the circuit scale. A light emitting diode driving circuit includes a reference current section for generating a reference current, and a current output section for generating a driving current based on the reference current using a current mirror circuit and supplying the driving current to a light emitting diode, wherein the reference current section includes: an operational amplifier for controlling the reference current so that a voltage generated by the reference current flowing through the resistance circuit becomes equal to a predetermined reference voltage; and a reference current switching circuit which is a resistance circuit formed of a series circuit of a plurality of resistors and transistors connected in parallel to the reference resistor, switches a voltage generated by the flow of the reference current by turning on or off the transistors of the series circuit in accordance with a control signal, and switches the reference current.
Description
Technical field
The present invention relates to LED driving circuit, relate to and drive each LED driving circuit of a plurality of light-emitting diodes be arranged.
Background technology
As the parts that make photoreceptor sensitization in the printer etc., have and use the led array that carries out light-emitting diode (below call " LED ") linear array.As the drive circuit of each LED that drives such led array, the drive circuit of in patent documentation 1,2 etc., putting down in writing is for example arranged.
Fig. 3 representes the circuit structure diagram of an example of existing LED driving circuit.This drive circuit is by semiconductor integrated.
In the figure, on the reversed input terminal of operational amplifier 10, applied reference voltage V ref by reference voltage source 11.The lead-out terminal of operational amplifier 10 connects the grid of p channel MOS field-effect transistor (being designated hereinafter simply as " MOS transistor ") M0; The grid that connects p channel MOS transistor M1 simultaneously; In addition, the grid that connects p channel MOS transistor M2, M3 through the switch 12,13 of analog switch etc.The source electrode of MOS transistor M0, M1, M2, M3 connects power supply Vdd1.MOS transistor M0, M1 constitute current mirror circuit, and MOS transistor M0 constitutes current mirror circuit with MOS transistor M1～M3 when switch 12,13 is connected.
Non-inverting input of the drain electrode concatenation operation amplifier 10 of MOS transistor M0 is simultaneously through resistance R 1 ground connection.The drain electrode of MOS transistor M1, M2, M3 connects the drain electrode of n channel MOS transistor M4 jointly. Switch 12,13 is according to switch controlling signal switched conductive/shutoff of using from the brilliance control of terminal 14a, each supply of 14b.
The drain electrode of MOS transistor M4 connects the grid of n channel MOS transistor M4, M5 jointly, the source ground of MOS transistor M4, M5, and MOS transistor M4, M5 constitute current mirror circuit.
The drain electrode of MOS transistor M5 connects grid and the drain electrode of p channel MOS transistor M6.Each connects the grid of p channel MOS transistor M7, M8 the switch 15,16 of the grid of MOS transistor M6 through analog switch etc.The source electrode of MOS transistor M6, M7, M8 connects power supply Vdd2, and the drain electrode of MOS transistor M7, M8 connects the anode of LED (light-emitting diode) 18, the minus earth of LED18.
Iref1＝Vref/R1 ...(1)
In the gate area of MOS transistor M1 and MOS transistor M2, M3 than being the occasion of 10:1; When switch 12 being connected make MOS transistor M2 conducting, add that on the drain current of MOS transistor M1 the drain current of MOS transistor M2 becomes the drain current of MOS transistor M4 (1.1 * A * Iref1).In addition, when switch 12,13 being connected make MOS transistor M2, M3 conducting, add that on the drain current of MOS transistor M1 the drain current of MOS transistor M2, M3 becomes the drain current of MOS transistor M4 (1.2 * A * Iref1).Because the drain current of this MOS transistor M4 becomes the drain current that second reference current decides MOS transistor M5, M6; So no matter gray scale performance; The electric current that flows through LED18 becomes 1.1 times through the connection of switch 12; And the luminosity that makes LED18 becomes about 1.1 times, and the connection through switch 12,13 becomes 1.2 times, and makes the luminosity of LED18 become about 1.2 times.
Patent documentation 1: specially permit communique No. 3296882
Patent documentation 2: specially permit communique No. 2516236
In existing LED driving circuit, with MOS transistor M1 switch 12 and MOS transistor M2, M3 are set side by side, through connection/shutoff control of carrying out switch 12,13, adjust the luminosity of LED18.
In this occasion, in the time will adjusting the luminosity of LED18, the progression that must make the switch that is provided with side by side with MOS transistor M1 and MOS transistor is increased to tens grades from tens grades, has circuit scale to become big such problem more carefully.
Summary of the invention
The present invention makes in view of the above problems, and its objective is provides a kind of LED driving circuit, and it can adjust the luminosity of light-emitting diode accurately, but also can suppress the increase of circuit scale.
LED driving circuit of the present invention is made up of the electric current efferent that reference current section that generates reference current and the generation of use current mirror circuit are supplied with light-emitting diode based on the drive current of said reference current,
Said reference current section,
Have:
Operational amplifier, it is controlled said reference current and becomes identical so that flow through the voltage that resistance circuit takes place through said reference current with the reference voltage of fixing; With
The reference current commutation circuit; It is the resistance circuit that parallelly connected a plurality of resistance with reference resistance and transistorized series circuit form; Make the transistor turns of said series circuit or shutoff switch voltage according to control signal through the mobile generation of said reference current; And switch said reference current
Thus, the luminosity of light-emitting diode can be adjusted accurately, and the increase of circuit scale can be suppressed.
In said LED driving circuit,
The resistance of said a plurality of series circuits can have the resistance value different with said reference resistance.
According to the present invention, can adjust the luminosity of light-emitting diode accurately, and can suppress the increase of circuit scale.
Description of drawings
Fig. 1 is to use the square construction drawing of an example of the led array device of LED driving circuit of the present invention.
Fig. 2 is the circuit structure diagram of an example of LED driving circuit of the present invention.
Fig. 3 is the circuit structure diagram of an example of existing LED driving circuit.
Symbol description
30 operational amplifiers
31 reference voltage source circuits
33 reference current section
34,35 voltage sources
36,38,40 switches
44 electric current efferents
45?LED
M11～M33 MOS transistor
R11～R23 resistance
Vdd1, Vdd2 power supply
Embodiment
Below according to description of drawings example of the present invention.
< structure of led array drive circuit >
Fig. 1 representes to use the square construction drawing of an example of the led array device of LED driving circuit of the present invention.This led array device for example is 48 channel designs.
In the figure, in shift register 20, after for example supplying with fluorescent lifetime data, these data of 6 and in shift register 20, the order displacement and latched for 1 passage, be supplied to pulse-width modulation circuit 22 with the time series of 48 numbers of channels.This pulse-width modulation circuit 22 generates the led pulse with the pulsewidth of fluorescent lifetime data indication for each passage, supplies with the led pulse of 48 numbers of channels to led array drive circuit 26.
For example supply with 6 fluorescent lifetime data for 1 passage for shift register 24, during these data are shifted by order and are locked, be supplied to led array drive circuit 26 in shift register 24 with the time series of 48 numbers of channels.Led array drive circuit 26 for each channel-decoded luminosity data, generates the switch controlling signal of n system, makes it the MOS transistor of conducting with led pulse for every passage through the switch controlling signal decision of said n system.Led array drive circuit 26 drives 48 LED channels that constitute led array 28 with passage unit.
< structure of LED driving circuit >
Fig. 2 is the circuit structure diagram of an example of LED driving circuit of the present invention.This drive circuit is by the semiconductor integrated circuit change.
In the figure, apply reference voltage V ref on the reversed input terminal of operational amplifier 30 through reference voltage source circuit 31.The lead-out terminal of operational amplifier 30 connects each grid of p channel MOS transistor M11, M12.MOS transistor M11, M12 source electrode separately connects power supply Vdd1 through R11, R12 respectively and constitutes current mirror circuit.MOS transistor M11, M12 drain electrode separately connects the source electrode of p channel MOS transistor M13, M14 respectively.
The drain electrode that the grid of MOS transistor M13, M14 is connected to MOS transistor M13 jointly constitutes current mirror circuit.The non-inverting input of the drain electrode concatenation operation amplifier 30 of MOS transistor M13 connects each a end of resistance 13, R14, R15, R16 simultaneously.The other end ground connection of resistance 13.
MOS transistor M11～M14, through making the structure of cascade current mirror circuit, the drain potential of MOS transistor M11, M12 is identical substantially, and in the identical occasion of gate area, the drain current of MOS transistor M13, M14 is identical substantially.
Resistance R 14, R15, the R16 other end separately connects the drain electrode of n channel MOS transistor M31, M32, M33, the source ground of MOS transistor M31, M32, M33.Supply with the switch controlling signal that brilliance control is used for the grid of MOS transistor M31, M32, M33 from terminal 32a, 32b, 32c.
The drain electrode of MOS transistor M14 connects the drain electrode of n channel MOS transistor M15.The grid that the grid of MOS transistor M15 connects n channel MOS transistor M16 constitutes the current mirror electric current.
MOS transistor M15, M16 source electrode separately connects the drain electrode of n channel MOS transistor M17, M18 respectively.The drain electrode that the grid of MOS transistor M17, M18 connects MOS transistor M15 jointly constitutes current mirror circuit, the source ground of MOS transistor M17, M18.
MOS transistor M15～M18, through making the structure of cascade current mirror circuit, the source potential of MOS transistor M15, M16 is identical substantially, and in the identical occasion of gate area, the drain current of MOS transistor M15, M16 is identical substantially.In addition, decide voltage Va through on the grid of MOS transistor M15, M16, applying with voltage source 34, the drain potential of MOS transistor M17, M18 becomes Va-Vgs1 (Vgs1 is a voltage between the grid drain electrode of n channel MOS transistor).
Above-mentioned operational amplifier 30, reference voltage source circuit 31, MOS transistor M11～M15 and M17 have constituted reference current section 33.Operational amplifier 30; The drain current of differential amplification through MOS transistor M13 flows through the drain voltage of the MOS transistor M13 that resistance R 13, R14, R15, R16 produce and from the reference voltage V ref of reference voltage source circuit 31; Make both become the drain current that identical that kind is controlled MOS transistor M11, make certain reference current Iref flow through the drain electrode of MOS transistor M13.In addition, through current mirror circuit, flow through the drain electrode of MOS transistor M16 with the proportional electric current of reference current Iref.
The drain electrode of MOS transistor M16 connects the drain electrode of p channel MOS transistor M22.The source electrode of MOS transistor M22 connects the drain electrode of p channel MOS transistor M21.The source electrode of MOS transistor M21 connects power supply Vdd2 through resistance R 15.
The grid of MOS transistor M21 connects the drain electrode of MOS transistor M22, simultaneously, connects the grid of p channel MOS transistor M23, M25, M27 through the switch 36,38,40 of analog switch etc.When switch 36,38,40 is connected; The grid potential of MOS transistor M23, M25, M27 is identical with the grid voltage of MOS transistor M21; MOS transistor M23, M25, M27 conducting; When switch 36,38,40 turn-offed, the grid potential of MOS transistor M23, M25, M27 was supply voltage Vdd2, and MOS transistor M23, M25, M27 turn-off.
MOS transistor M23, M25, M27 source electrode separately connects power supply Vdd2 through resistance R 21, R22, R23 respectively, MOS transistor M23, M25, M27 when switch 36,38,40 is connected and MOS transistor M21 constitute current mirror circuit.
The grid of MOS transistor M22 connects the grid of p channel MOS transistor M24, M26, M28.MOS transistor M23, M25, M27 drain electrode separately connects the source electrode of MOS transistor M24, M26, M28 respectively, and MOS transistor M22, M24, M26, M28 constitute current mirror circuit.
MOS transistor M21～M28; Through making the structure of cascade current mirror circuit; The drain potential of MOS transistor M21, M23, M25, M27 is identical substantially, and in the identical occasion of gate area, the drain current of MOS transistor M22, M24, M26, M28 is identical substantially.Here; For carrying out the gray scale performance; For example with respect to the gate area of MOS transistor M21, M22, let the gate area of MOS transistor M23, M24 be 6 times respectively, the gate area of MOS transistor M25, M26 is 3 times; The gate area of MOS transistor M27, M28 is 2 times, makes gate area different.
In addition, on the grid of MOS transistor M22, M24, M26, M28, apply through voltage source 35 and decide voltage Vb, the source potential that makes MOS transistor M22, M24, M26, M28 is Vb+Vgs2 (Vgs2 is a voltage between the grid drain electrode of p channel MOS transistor).
Here, MOS transistor M23, M25, M27 turn-offed when switch 36,38,40 turn-offed, and LED45 does not flow through electric current.The drain current of MOS transistor M23 flows through LED45 when switch 36 is connected; When switch 36,38 is connected the drain current of MOS transistor M23, M25 and flow through LED45; When switch 36,38,40 is connected the drain current of MOS transistor M23, M25, M27 and flow through LED45; The electric current that flows through LED45 is big more, and luminosity is big more.
The electric current efferent 44 of same structure that above-mentioned switch 36,38,40, MOS transistor M16, M18～M28 constitutes electric current efferent 44,48 passages of 1 passage is connected reference current section 33.The electric current efferent 44 of each passage drives the LED45 (part of led array 28) that connects separately.
< the brightness adjustment of light-emitting diode >
Here, each the ratio of resistance value of resistance R 13, R14, R15, R16, as get 1:2:4:8.When the switch controlling signal from terminal 32a～32c all was low level, MOS transistor M31～M33 turn-offed, and the drain electrode of MOS transistor M13 is through resistance R 13 ground connection.
MOS transistor M31 conducting when the switch controlling signal from terminal 32a is high level, the drain electrode of MOS transistor M13 is through the parallelly connected ground connection of resistance R 13 and resistance R 14.Equally; MOS transistor M32 conducting when the switch controlling signal from terminal 32b is high level; The drain electrode of MOS transistor M13 is through the parallelly connected ground connection of resistance R 13 and resistance R 15; When the switch controlling signal from terminal 32c is high level, MOS transistor M33 conducting, the drain electrode of MOS transistor M13 is through the parallelly connected ground connection of resistance R 13 and resistance R 16.
In addition; MOS transistor M31, M32 conducting when the switch controlling signal from terminal 32a, 32b is high level; The drain electrode of MOS transistor M13 is through the parallelly connected ground connection of resistance R 13 with resistance R 14 and R15; MOS transistor M32, M33 conducting when the switch controlling signal from terminal 32b, 32c is high level; The drain electrode of MOS transistor M13 is through the parallelly connected ground connection of resistance R 13 with resistance R 15 and resistance R 16; MOS transistor M31, M33 conducting when the switch controlling signal from terminal 32a, 32c is high level; The drain electrode of MOS transistor M13 is through the parallelly connected ground connection of resistance R 13 with resistance R 14 and resistance R 16, and resistance R 13 and the parallelly connected ground connection of resistance R 14 with resistance R 15 and resistance R 16 are passed through in MOS transistor M31, M32, M33 conducting when the switch controlling signal from terminal 32a, 32b, 32c is high level, the drain electrode of MOS transistor M13.
That is, can make resistance R 13 to the drain resistance maximum of MOS transistor M13, minimum is made (R13//R14//R15//R16).In addition, R13//R14//R15//R16 representes the combined resistance of the parallel connection of resistance R 13, R14, R15, R16.
Thus, the minimum value Iref (min) of the first reference current Iref that flows through the drain electrode of MOS transistor M13 representes that with (2) formula maximum Iref (max) representes with (3) formula.
Iref(min)＝Vref/R13 ...(2)
Iref(max)＝Vref/(R13//R14//R15//R16) ...(3)
In the present invention, through flow through the first reference current Iref of the drain electrode of MOS transistor M13 from the switch controlling signal adjustment of terminal 32a～32c, so that the luminosity of LED45 is a desired value.
In the prior art; In the time will adjusting the luminosity of LED18 more carefully; Must be increased to tens grades to the progression of the MOS transistor that is set up in parallel with MOS transistor M1 from tens grades; But use the simple structure of MOS transistor M31, M32, M33 and resistance R 14, R15, R16 in the present invention, just can carry out the brightness adjustment of 2N kind when the figure place of supposing switching signal is N.
In addition, resistance R 13 is suitable with the described reference resistance of claim, and resistance R 13～R16, MOS transistor M31～M33 and resistance circuit are suitable with the reference current commutation circuit.
More than specify preferred embodiment of the present invention, but the invention is not restricted to so specific example, can carry out various distortion changes within the scope of the claims in the scope of the aim of the present invention of record.
The priority that No. the 2006-171848, Japan's patent application that the application requires to submit to based on June 21st, 2006 is in this application through with reference to the full content of quoting this japanese publication.
Claims (2)
1. LED driving circuit, it is by the reference current section that generates reference current and use current mirror circuit to generate electric current efferent of supplying with light-emitting diode based on the drive current of said reference current and form, it is characterized in that,
Said reference current section,
Have:
Operational amplifier, it is controlled said reference current and becomes identical so that flow through the voltage that resistance circuit takes place through said reference current with certain reference voltage; With
The reference current commutation circuit; It is parallelly connected a plurality of resistance with reference resistance and the formed resistance circuit of transistorized series circuit; It makes the transistor turns of said series circuit or turn-off according to control signal switches owing to flow through the voltage that said reference current takes place; And switch said reference current; The transistor that wherein said polyphone connects comprises first to the 5th MOS transistor (M11-M15) and the 7th MOS transistor (M17); The lead-out terminal of operational amplifier (30) connects each grid of first MOS transistor (M11), second MOS transistor (M12), and first MOS transistor (M11), second MOS transistor (M12) source electrode separately are connected power supply formation current mirror circuit through first resistance (R11) respectively with second resistance (R12); First MOS transistor (M11), second MOS transistor (M12) drain electrode separately connect the source electrode of the 3rd MOS transistor (M13), the 4th MOS transistor (M14) respectively; The drain electrode that the grid of the 3rd MOS transistor (M13), the 4th MOS transistor (M14) is connected to the 3rd MOS transistor (M13) jointly constitutes current mirror circuit; Drain electrode concatenation operation amplifier's non-inverting of the 3rd MOS transistor (M13); The drain electrode of the 4th MOS transistor (M14) connects the drain electrode of the 5th MOS transistor (M15); The grid that the grid of the 5th MOS transistor (M15) connects the 6th MOS transistor (M16) constitutes the current mirror electric current; The source electrode of the 5th MOS transistor (M15) connects the drain electrode of the 7th MOS transistor (M17); The drain electrode that the grid of the 7th MOS transistor (M17) connects the 5th MOS transistor (M15) constitutes current mirror circuit, the source ground of the 7th MOS transistor (M17).
2. LED driving circuit according to claim 1 is characterized in that,
The resistance value of the resistance of said a plurality of series circuits is different with said reference resistance.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP171848/2006 | 2006-06-21 | ||
| JP2006171848A JP2008004706A (en) | 2006-06-21 | 2006-06-21 | Light-emitting diode driving circuit |
| PCT/JP2007/061922 WO2007148581A1 (en) | 2006-06-21 | 2007-06-13 | Light emitting diode driving circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101473456A CN101473456A (en) | 2009-07-01 |
| CN101473456B true CN101473456B (en) | 2012-05-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2007800224763A Expired - Fee Related CN101473456B (en) | 2006-06-21 | 2007-06-13 | Light emitting diode driving circuit |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2008004706A (en) |
| CN (1) | CN101473456B (en) |
| WO (1) | WO2007148581A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4847486B2 (en) * | 2008-03-25 | 2011-12-28 | 株式会社沖データ | Drive circuit, LED head, and image forming apparatus |
| JP2011258797A (en) * | 2010-06-10 | 2011-12-22 | Fujitsu Semiconductor Ltd | Drive control circuit of light-emitting diode and backlight system |
| CN102348311A (en) * | 2010-08-02 | 2012-02-08 | 艾笛森光电股份有限公司 | Light-emitting diode (LED) driving circuit |
| JP5794835B2 (en) * | 2011-06-13 | 2015-10-14 | セミコンダクター・コンポーネンツ・インダストリーズ・リミテッド・ライアビリティ・カンパニー | Light emitting element drive circuit |
| US9198255B2 (en) * | 2013-03-14 | 2015-11-24 | Nxp B.V. | Voltage to current architecture to improve PWM performance of output drivers |
| CN109568697B (en) * | 2018-12-10 | 2024-06-18 | 广东宝莱特医用科技股份有限公司 | Blood detection device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001237489A (en) * | 2000-02-22 | 2001-08-31 | Yamaha Corp | Laser diode drive circuit |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3440518B2 (en) * | 1993-11-26 | 2003-08-25 | オムロン株式会社 | Proximity switch |
| JPH11234218A (en) * | 1998-02-18 | 1999-08-27 | Fuji Electric Co Ltd | Signal transmission circuit |
| JP4604299B2 (en) * | 2000-01-28 | 2011-01-05 | ソニー株式会社 | Signal processing circuit and bias adjustment circuit |
| JP2005260001A (en) * | 2004-03-11 | 2005-09-22 | Seiko Epson Corp | Light emitting element driver circuit |
| JP2005323178A (en) * | 2004-05-10 | 2005-11-17 | Olympus Corp | Information terminal apparatus |
| JP2006060751A (en) * | 2004-08-24 | 2006-03-02 | Ricoh Co Ltd | Output device, differential output device, semiconductor laser modulation driving apparatus, image forming apparatus and electronic equipment |
| JP4116003B2 (en) * | 2005-02-14 | 2008-07-09 | 日本テキサス・インスツルメンツ株式会社 | Current drive circuit |
-
2006
- 2006-06-21 JP JP2006171848A patent/JP2008004706A/en active Pending
-
2007
- 2007-06-13 CN CN2007800224763A patent/CN101473456B/en not_active Expired - Fee Related
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001237489A (en) * | 2000-02-22 | 2001-08-31 | Yamaha Corp | Laser diode drive circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101473456A (en) | 2009-07-01 |
| JP2008004706A (en) | 2008-01-10 |
| WO2007148581A1 (en) | 2007-12-27 |
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