CN105282897A - Light-emitting diode driving circuit and driving method - Google Patents

Light-emitting diode driving circuit and driving method Download PDF

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Publication number
CN105282897A
CN105282897A CN201410238389.3A CN201410238389A CN105282897A CN 105282897 A CN105282897 A CN 105282897A CN 201410238389 A CN201410238389 A CN 201410238389A CN 105282897 A CN105282897 A CN 105282897A
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China
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voltage
circuit
resistance
light
level
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熊大嵩
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Mitac Computer Kunshan Co Ltd
Getac Technology Corp
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Mitac Computer Kunshan Co Ltd
Mitac Technology Corp
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Priority to CN201410238389.3A priority Critical patent/CN105282897A/en
Publication of CN105282897A publication Critical patent/CN105282897A/en
Pending legal-status Critical Current

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Abstract

The invention discloses a diode driving circuit and driving method. Light regulating voltage is generated by regulating level of sensing voltage outputted by a light sensor through a regulating circuit so that a problem of mismatching of sensing voltage outputted by the light sensor and voltage required by a driving unit can be solved, and trouble of component selection in design can also be avoided. Besides, the regulating circuit can also comprise a charge and discharge circuit for performing charge and discharge of light regulating voltage for linear output so that light regulating voltage is enabled to rise to the preset level, and an objective of gradual light regulation of a light-emitting diode can be achieved.

Description

The drive circuit of light-emitting diode and driving method
[technical field]
The present invention about a kind of drive circuit and driving method, the drive circuit of its espespecially a kind of light-emitting diode and driving method.
[background technology]
Light-emitting diode (Light-EmittingDiode, LED) is a kind of semi-conductor electricity sub-component that can be luminous, and be made up of the semi-conducting material of P type and N-type, it can produce the autoradiolysis light in ultraviolet, visible ray and infrared spectral range.Because light-emitting diode has the plurality of advantages such as power saving, the life-span is long, brightness is high, recently under the trend of environmental protection and energy-saving and carbon-saving, the application of light-emitting diode is more and more extensive, such as traffic sign, street lamp, flashlight, display device or lighting device etc.
There are many electronic installations (such as display floater) needing to carry out light-emitting diode according to surround lighting light modulation at present, this kind of electronic installation is generally by an ambient light sensor (Ambientlightsensor) to sense the intensity of surrounding environment light, and the intensity of foundation surround lighting adjusts the brightness (such as display floater can remain on optimal comfort brightness whereby and at any time) of light-emitting diode automatically.But existing light sensing dimmer design is failed fully up to expectations, reason is that its dimming effect cannot absolutely control, and existing light sensing dimmer design is stepping light modulation and cannot reaches gradual effect.
Refer to Fig. 1, it is the circuit diagram of the drive circuit of existing light-emitting diode.As shown in the figure, the drive circuit of existing light-emitting diode comprises optical sensor 10 and a driver element 20.Optical sensor 10 receives an enabling signal SS, and starts according to enabling signal SS, to carry out light sensing.Optical sensor 10 produces a sensing voltage V according to the intensity of sensed light sEN.One brilliance control pin DBRT of driver element 20 receives this sensing voltage V sEN, with foundation sensing voltage V sENvoltage quasi position and learn the intensity of the light that optical sensor 10 senses, and the power of corresponding light produces the drive current in order to drive light-emitting diode, and adjusts the brightness of light-emitting diode.
But, general optical sensor can be had nothing in common with each other according to the optical sensor of all size according to the voltage quasi position of the sensing voltage that the intensity of light source produces, take model as the optical sensor of CM3204 be example, its sensing voltage exported is about 0 ~ 1.5V, and the required voltage quasi position received of driver element is also had nothing in common with each other according to different manufactory, if when optical sensor cannot mate with driver element, easily there is the incomplete situation of light modulation.In other words, the optical sensor of specific standard only can be arranged in pairs or groups the driver element of specific standard, so, often causes the puzzlement of establishing time pieces to select.
Moreover, the sensing voltage exported due to general optical sensor is stepping, therefore when driver element receive this step-type sensing voltage with compared with internal signal time, can cause exported drive current is also stepwise change, and then cause the light modulation of light-emitting diode to be also stepping, long-term viewing is got off, and can cause injury to a certain degree to human eye.
Therefore, the present invention is directed to drive circuit and driving method that the problems referred to above provide a kind of light-emitting diode, begin to solve the above problems.
[summary of the invention]
An object of the present invention, is the drive circuit and the driving method that provide a kind of light-emitting diode, the level of sensing voltage exported by Circuit tuning adjustment optical sensor, to mate the voltage needed for driver element, and avoids the puzzlement of establishing time pieces to select.
An object of the present invention, be drive circuit and driving method that a kind of light-emitting diode is provided, it provides sensing voltage and reference voltage to Circuit tuning simultaneously, when level lower than reference voltage of the level of sensing voltage, Circuit tuning adjusts the level of reference voltage to produce dimmer voltage, to provide light-emitting diode one minimum brightness.
An object of the present invention, be drive circuit and driving method that a kind of light-emitting diode is provided, by charge-discharge circuit, discharge and recharge is carried out and linear convergent rate to dimmer voltage, make dimmer voltage linearly rise to predetermined level, to reach the object to the gradual light modulation of light-emitting diode.
In order to reach above-mentioned censured each object and effect, present invention is disclosed a kind of drive circuit of light-emitting diode, it comprises: an optical sensor, senses a light source, and produces a sensing voltage according to light source; One generating circuit from reference voltage, produces a reference voltage; One Circuit tuning, receives sensing voltage or reference voltage, and adjusts the level of sensing voltage or reference voltage and produce a dimmer voltage; And a driver element, receive dimmer voltage, and produce at least one drive current, to drive the some light-emitting diodes coupling driver element according to dimmer voltage; Wherein, when level higher than reference voltage of the level of sensing voltage, the level of Circuit tuning adjustment sensing voltage produces dimmer voltage.
Present invention further teaches a kind of driving method of light-emitting diode, its step comprises: sense a light source, and produces a sensing voltage according to light source; The level of adjustment sensing voltage or a reference voltage and produce a dimmer voltage, when level higher than reference voltage of the level of sensing voltage, the level of Circuit tuning adjustment sensing voltage produces dimmer voltage; And produce at least one drive current, to drive some light-emitting diodes according to dimmer voltage.
Compared to prior art, the drive circuit of light-emitting diode of the present invention and driving method, by a Circuit tuning to adjust the level of the sensing voltage of optical sensor output, and produce a dimmer voltage, to solve the unmatched problem of voltage needed for sensing voltage and driver element that optical sensor exports, and the puzzlement of establishing time pieces to select can be avoided.In addition, Circuit tuning of the present invention also can comprise a charge-discharge circuit, to carry out discharge and recharge to dimmer voltage and linear convergent rate, makes dimmer voltage linearly rise to predetermined level, to reach the object to the gradual light modulation of light-emitting diode.
[accompanying drawing explanation]
Fig. 1 is the circuit diagram of the drive circuit of existing light-emitting diode;
Fig. 2 is the circuit diagram of the drive circuit of the light-emitting diode of a preferred embodiment of the present invention;
Fig. 3 is the detailed circuit diagram of the drive circuit of the light-emitting diode of the first embodiment of the present invention;
Fig. 4 is the detailed circuit diagram of the drive circuit of the light-emitting diode of the second embodiment of the present invention;
Fig. 5 is the detailed circuit diagram of the drive circuit of the light-emitting diode of the third embodiment of the present invention; And
Fig. 6 is the oscillogram of the switching signal of a preferred embodiment of the present invention.
[embodiment]
Refer to Fig. 2, it is the circuit diagram of the drive circuit of the light-emitting diode of a preferred embodiment of the present invention.As shown in the figure, the drive circuit of light-emitting diode of the present invention comprises Circuit tuning 30 and a driver element 20.Circuit tuning 30 receives the sensing voltage VSEN that a reference voltage VREF and an optical sensor 10 (as shown in Figure 3) produce according to the intensity of the light source (such as surround lighting) sensed, Circuit tuning 30 select reference voltage VREF or sensing voltage VSEN wherein one carry out adjusting (such as amplifying) after, produce a dimmer voltage VDIM.One brilliance control pin DBRT of driver element 20 receives dimmer voltage VDIM, the intensity of the light source that optical sensor 10 senses is learnt with the level according to dimmer voltage VDIM, and the intensity of corresponding light source produces at least one drive current ID, drive current ID drives the some light-emitting diodes in a light-emitting diode (LED) module 40 by driver element 20, and the magnitude of current size of drive current ID is adjusted according to dimmer voltage VDIM.
Wherein, when level higher than reference voltage VREF of the level of sensing voltage VSEN, Circuit tuning 30 adjusts the level of sensing voltage VSEN to produce dimmer voltage VDIM.And when level lower than reference voltage VREF of the level of sensing voltage VSEN, Circuit tuning 30 adjusts the level of reference voltage VREF to produce dimmer voltage VDIM, makes driver element 20 provide these light-emitting diode one minimum brightnesses of light-emitting diode (LED) module 40 according to this dimmer voltage VDIM.
So, the present invention adjusts the level of reference voltage VREF or sensing voltage VSEN to the voltage quasi position needed for driver element 20 by Circuit tuning 30, to mate driver element 20, even originally, when the sensing voltage VSEN that optical sensor 10 exports does not mate with the voltage needed for driver element 20, the present invention adjusts the level of sensing voltage VSEN by Circuit tuning 30, and the dimmer voltage VDIM produced needed for driver element 20, therefore, existing mode can be solved and must select the optical sensor and driver element that match each other, and cause the problem of establishing time pieces to select puzzlement.
See also Fig. 3, it is the detailed circuit diagram of the drive circuit of the light-emitting diode of the first embodiment of the present invention.Compared to the drive circuit of the light-emitting diode of Fig. 2, the drive circuit of the light-emitting diode of Fig. 3 also comprises a generating circuit from reference voltage 50, to produce reference voltage VREF.Wherein, optical sensor 10 receives an enabling signal SS, and starts according to enabling signal SS, and to sense a light source (such as surround lighting), optical sensor 10 produces sensing voltage VSEN according to the intensity of sensed light source.Generating circuit from reference voltage 50 for generation of and reference voltage VREF is provided.
Circuit tuning 30 couples optical sensor 10 and generating circuit from reference voltage 50, and select receive sensing voltage VSEN or reference voltage VREF one of them, dimmer voltage VDIM is produced to adjust the level of sensing voltage VSEN or reference voltage VREF, and provide dimmer voltage VDIM to the brilliance control pin DBRT of driver element 20, and then the brightness of these light-emitting diodes of adjustment light-emitting diode (LED) module 40.
In the present embodiment, optical sensor 10 receives enabling signal SS via a resistance R1, and via a resistance R2 output sensing voltage VSEN, and couple this earth terminal via a resistance R3 and an electric capacity C1 respectively, but this partial circuit (resistance R1, R2, R3 and electric capacity C1) designs needed for the optical sensor according to different size, be not necessary circuit, be also not intended to limit the present invention.
Generating circuit from reference voltage 50 comprises a bleeder circuit, and bleeder circuit receives an input voltage vin and couples this earth terminal, and dividing potential drop input voltage vin is to produce reference voltage VREF.Bleeder circuit can comprise some resistance R4, R5 and a diode D1.One first end of resistance R4 receives input voltage vin, one second end of the one first end coupling resistance R4 of resistance R5, one second end of resistance R5 then couples this earth terminal, resistance R4 and R5 dividing potential drop input voltage vin, and produces reference voltage VREF in the first end of resistance R5.Second end of one anode tap coupling resistance R4 of diode D1 and the first end of resistance R5, a cathode terminal of diode D1 then couples Circuit tuning 30, to be sent to Circuit tuning 30 via diode D1 with reference to voltage VREF.
In addition, the drive circuit of the present embodiment also can comprise a diode D2, one anode tap of diode D2 couples optical sensor 10, and a cathode terminal of diode D2 then couples Circuit tuning 30, and the sensing voltage VSEN that optical sensor 10 exports is sent to Circuit tuning 30 via diode D2.Above-mentioned diode D1 and D2 is all for preventing the electric current adverse current of Circuit tuning 30 side, and the present invention is by this circuit framework, when making level higher than reference voltage VREF of level as sensing voltage VSEN, only sensing voltage VSEN is sent to Circuit tuning 30, and when level lower than reference voltage VREF of the level of sensing voltage VSEN, be only sent to Circuit tuning 30 with reference to voltage VREF.
The Circuit tuning 30 of the present embodiment comprises an operational amplifier OP and some resistance R6, R7.One positive input terminal of operational amplifier OP receives an output output dimmer voltage VDIM of sensing voltage VSEN or reference voltage VREF, operational amplifier OP.Resistance R6 is coupled between a negative input end of operational amplifier OP and output.Resistance R7, between the negative input end being coupled to operational amplifier OP and earth terminal.The circuit formed due to operational amplifier OP and resistance R6, R7 is noninverting amplifying circuit, therefore the level of dimmer voltage VDIM determines with the ratio of the resistance value of resistance R7 according to resistance R6, as shown in following formula (1), but Circuit tuning 30 of the present invention does not limit and is made up of noninverting amplifying circuit, also can be made up of the circuit of other adjustable-voltage levels.
Wherein, the sensing voltage VSEN that the positive input terminal that VI is operational amplifier OP receives or reference voltage VREF.
So, the present embodiment is by the noninverting amplifying circuit (operational amplifier OP and resistance R6, R7) of Circuit tuning 30, and adjust the level of reference voltage VREF or sensing voltage VSEN to the level needed for driver element 20, must select to solve existing mode the optical sensor and driver element that match each other, and the time pieces of establishing caused selects the problem of puzzlement.
In addition, the brilliance control pin DBRT of the driver element 20 of the present embodiment also couples a resistance R8, to receive a pulse wave width modulation signal PWM via resistance R8, and the frequency that pulse wave width modulation signal PWM gives tacit consent in order to provide driver element 20 1.
See also Fig. 4, it is the detailed circuit diagram of the drive circuit of the light-emitting diode of the second embodiment of the present invention.The difference of the present embodiment and previous embodiment is, the Circuit tuning 30 of the present embodiment also comprises a charge-discharge circuit, and remainder is then identical, and repeats no more.
As shown in Figure 4, Circuit tuning 30 comprises a charge-discharge circuit, charge-discharge circuit comprises an a resistance R9 and electric capacity C3, one first end of resistance R9 couples the output of operational amplifier OP, to receive the voltage (representing with an output voltage VO UT in the present embodiment) that operational amplifier OP exports, second end of resistance R9 couples driver element 20.Second end of the one first end coupling resistance R9 of electric capacity C3, one second end of electric capacity C3 couples this earth terminal, with discharge and recharge is carried out to output voltage VO UT and linear convergent rate for dimmer voltage VDIM.
From the above, the present embodiment is the linear convergent rate dimmer voltage VDIM by charge-discharge circuit also, dimmer voltage VDIM is namely made linearly to rise to predetermined level, to solve the sensing voltage of existing optical sensor output for stepping, therefore when driver element receive this step-type sensing voltage with compared with internal signal time, exported drive current can be caused to be stepwise change, and then the light modulation causing light-emitting diode is also stepping, and to the problem that human eye damages.
Refer to Fig. 5, it is the circuit diagram of the drive circuit of the light-emitting diode of the third embodiment of the present invention.The difference of the present embodiment and previous embodiment is, the present embodiment also comprises some diode D3, D4, and remainder is then same as previous embodiment and repeats no more.One cathode terminal of the one anode tap coupling resistance R8 of diode D3, diode D3 then couples the brilliance control pin DBRT of driver element 20, to transmit pulse wave width modulation signal PWM via diode D3 to brilliance control pin DBRT.One anode tap of diode D4 couples the resistance R9 of Circuit tuning 30, and a cathode terminal of diode D4 then couples the brilliance control pin DBRT of driver element 20, to transmit dimmer voltage VDIM to brilliance control pin DBRT via diode D4.So, the signal adverse current on brilliance control pin DBRT can be prevented, and cause dimmer voltage VDIM and pulse wave width modulation signal PWM to interfere with each other.
See also Fig. 6, it is the oscillogram of the switching signal of a preferred embodiment of the present invention.Dimmer voltage VDIM inputs to driver element 20 to compare with a reference signal STS1 of driver element 20 inside, and driver element 20 produces a switching signal SW to switch generation drive current ID according to comparative result, as shown in the figure, reference signal STS1 is a sawtooth signal, when reference signal STS1 rises to higher than dimmer voltage VDIM, driver element 20 produces the switching signal SW of low level, and when reference signal STS1 drops to lower than dimmer voltage VDIM, driver element 20 produces the switching signal SW of high levle, to provide drive current ID to these light-emitting diodes of light-emitting diode (LED) module 40.
From the above, the present embodiment passes through dimmer voltage VDIM as threshold value, to compare with reference signal STS1, and due to the level of dimmer voltage VDIM be the power of the light source sensed according to optical sensor 10 and height to some extent, therefore switching signal SW is the power of the light source that foundation optical sensor 10 senses and has different duty ratios, and then the brightness of these light-emitting diodes of adjustment light-emitting diode (LED) module 40.
In sum, the drive circuit of light-emitting diode of the present invention and driving method, by a Circuit tuning to adjust the level of the sensing voltage of optical sensor output, and produce a dimmer voltage, to solve the unmatched problem of voltage needed for sensing voltage and driver element that optical sensor exports, and the puzzlement of establishing time pieces to select can be avoided.In addition, Circuit tuning of the present invention also can comprise a charge-discharge circuit, to carry out discharge and recharge to dimmer voltage and linear convergent rate, makes dimmer voltage linearly rise to predetermined level, to reach the object to the gradual light modulation of light-emitting diode.

Claims (14)

1. a drive circuit for light-emitting diode, is characterized in that, it comprises:
One optical sensor, senses a light source, and produces a sensing voltage according to this light source;
One generating circuit from reference voltage, produces a reference voltage;
One Circuit tuning, receives this sensing voltage or this reference voltage, and adjusts the level of this sensing voltage or this reference voltage and produce a dimmer voltage; And
One driver element, receives this dimmer voltage, and produces at least one drive current according to this dimmer voltage, to drive the some light-emitting diodes coupling this driver element;
Wherein, when level higher than this reference voltage of the level of this sensing voltage, the level that this Circuit tuning adjusts this sensing voltage produces this dimmer voltage.
2. drive circuit as claimed in claim 1, it is characterized in that, when level lower than this reference voltage of the level of this sensing voltage, this Circuit tuning adjusts the level of this reference voltage to produce this dimmer voltage, makes this driver element drive these light-emitting diodes according to this dimmer voltage and provide a minimum brightness.
3. drive circuit as claimed in claim 1, it is characterized in that, this generating circuit from reference voltage comprises:
One bleeder circuit, receives an input voltage and couples an earth terminal, and this input voltage of dividing potential drop produces this reference voltage.
4. drive circuit as claimed in claim 3, it is characterized in that, this bleeder circuit comprises:
One first resistance, have a first end and one second end, this first end of this first resistance receives this input voltage; And
One second resistance, there is a first end and one second end, this first end of this second resistance couples this second end of this first resistance, this second end of this second resistance couples an earth terminal, this first resistance and this this input voltage of the second electric resistance partial pressure, and produce this reference voltage in this first end of this second resistance.
5. drive circuit as claimed in claim 4, it is characterized in that, this generating circuit from reference voltage also comprises:
One diode, has an anode tap and a cathode terminal, and this anode tap of this diode couples this second end of this first electricity group to receive this reference voltage, and this cathode terminal of this diode couples this Circuit tuning.
6. drive circuit as claimed in claim 1, is characterized in that, its evil comprises:
One diode, has an anode tap and a cathode terminal, and this anode tap of this diode couples this optical sensor, and this cathode terminal of this diode couples this Circuit tuning, and this sensing voltage is sent to this Circuit tuning via this diode.
7. drive circuit as claimed in claim 1, it is characterized in that, this Circuit tuning comprises:
One operational amplifier, has a positive input terminal, a negative input end and an output, and this positive input terminal of this operational amplifier receives this sensing voltage or this reference voltage, and this output of this operational amplifier exports this dimmer voltage;
One first resistance, is coupled between this negative input end of this operational amplifier and this output; And
One second resistance, is coupled between this negative input end of this operational amplifier and an earth terminal.
8. drive circuit as claimed in claim 7, is characterized in that, the level of this dimmer voltage determines according to the resistance value of this first resistance and this second resistance.
9. drive circuit as claimed in claim 1, it is characterized in that, this Circuit tuning comprises:
One operational amplifier, has a positive input terminal, a negative input end and an output, and this positive input terminal of this operational amplifier receives this sensing voltage or this reference voltage, and this output of this operational amplifier exports an output voltage;
One first resistance, is coupled between this negative input end of this operational amplifier and this output;
One second resistance, is coupled between this negative input end of this operational amplifier and an earth terminal; And
One charge-discharge circuit, receives this output voltage, and linearly exports this dimmer voltage to this driver element according to this output voltage.
10. drive circuit as claimed in claim 9, it is characterized in that, this charge-discharge circuit comprises:
One the 3rd resistance, has a first end and one second end, and this first end of the 3rd resistance couples this output of this operational amplifier to receive this output voltage, and this second end of the 3rd resistance couples this driver element; And
One electric capacity, has a first end and one second end, and this first end of this electric capacity couples this second end of the 3rd resistance, and this second end of this electric capacity couples this earth terminal, to carry out discharge and recharge to this output voltage and linear convergent rate is this dimmer voltage.
The driving method of 11. 1 kinds of light-emitting diodes, is characterized in that, it comprises step:
Sense a light source, and produce a sensing voltage according to this light source;
Adjust the level of this sensing voltage or a reference voltage and produce a dimmer voltage, when level higher than this reference voltage of the level of this sensing voltage, the level that this Circuit tuning adjusts this sensing voltage produces this dimmer voltage; And
At least one drive current is produced, to drive some light-emitting diodes according to this dimmer voltage.
12. driving methods as claimed in claim 11, it is characterized in that, it also comprises:
When level lower than this reference voltage of the level of this sensing voltage, adjust the level of this reference voltage to produce this dimmer voltage; And
Drive these light-emitting diodes according to this dimmer voltage and a minimum brightness is provided.
13. driving methods as claimed in claim 11, it is characterized in that, this reference voltage is produced by a bleeder circuit of acceptance one input voltage.
14. driving methods as claimed in claim 11, is characterized in that, in producing at least one drive current according to this dimmer voltage, comprise to drive in the step of some light-emitting diodes:
Relatively this dimmer voltage and a reference signal, and produce a switching signal; And
Switch a power switch according to this switching signal, output current to these light-emitting diodes to provide this.
CN201410238389.3A 2014-05-30 2014-05-30 Light-emitting diode driving circuit and driving method Pending CN105282897A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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Application Number Priority Date Filing Date Title
CN201410238389.3A CN105282897A (en) 2014-05-30 2014-05-30 Light-emitting diode driving circuit and driving method

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CN105282897A true CN105282897A (en) 2016-01-27

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Application publication date: 20160127