CN100558207C - Current control device - Google Patents
Current control device Download PDFInfo
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- CN100558207C CN100558207C CNB2007100038583A CN200710003858A CN100558207C CN 100558207 C CN100558207 C CN 100558207C CN B2007100038583 A CNB2007100038583 A CN B2007100038583A CN 200710003858 A CN200710003858 A CN 200710003858A CN 100558207 C CN100558207 C CN 100558207C
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Abstract
The invention discloses a kind of current control device, be suitable for the electric current that control flows is crossed the light-emitting component string, wherein a wherein end of light-emitting component string electrically connects first current potential.Current control device comprises current adjustment unit and control unit.Current adjustment unit is electrically connected between the other end of second current potential and light-emitting component string, in order to detect the electric current of light-emitting component string, produce feedback signal according to this, and remove to control resistance value between the light-emitting component string and second current potential, and then the electric current of control light-emitting component string according to conducting control signal and impedance control signal.Control unit is electrically connected to current adjustment unit, value in order to reception and comparison reference signal and feedback signal, producing comparative result, and comparative result is done current compensation, and the comparative result that will finish behind the current compensation converts conducting control signal and impedance control signal to.
Description
Technical field
The invention relates to a kind of current control device, and, reach the current control device of the brightness of adjusting light emitting diode string particularly relevant for a kind of electric current that utilizes FEEDBACK CONTROL adjustment to flow through light emitting diode string.
Background technology
At liquid crystal display television (Liquid Crystal Display Television, abbreviation LCD TV) light-emitting diode (Light Emitting Diode, abbreviation LED) in the backlight, need a large amount of light-emitting diode of utilization that brightness is reached and the suitable specification of cold-cathode fluorescence lamp (Cold Cathode Fluorescent Lamp is called for short CCFL).In general design; for the number of the drive integrated circult (DrivingIntegrated Circuit) that reduces light-emitting diode and total drive current of light-emitting diode, so the design circuit that back light source in LED need use many light-emitting diodes series connection to light through regular meeting.This mode not only can reduce the group number of drive integrated circult, also can reduce total drive current of light-emitting diode, and further lowers the consumed power of drive integrated circult.
Yet because light-emitting diode is in the process of making, be difficult to control to cut-in voltage (the Cut-in Voltage of each light-emitting diode, promptly be the minimum voltage that makes the light-emitting diode conducting) reach in full accord, so plant the shortcoming of control mode, the error amount of cut-in voltage of each light-emitting diode will add up, cause under the condition of fixing input voltage, the electric current of each group light emitting diode string is understood because its total cut-in voltage is different difference to some extent, therefore cause and respectively organize light emitting diode string and produces the different phenomenon of brightness because of electric current is inconsistent, this kind phenomenon will cause the phenomenon generation of the inhomogeneous and coloured inequality of back light source brightness of panel.
In order to solve so problem, there are some to utilize the gimmick of improving of current mirror to be suggested successively, for example the circuit that disclosed for No. 5701133 of United States Patent (USP) promptly is an example wherein, as shown in Figure 1.Fig. 1 is existing brightness regulating circuit.Please refer to Fig. 1, the VLED among Fig. 1 is expressed as supply voltage, and GND is expressed as earthed voltage, and Vin is expressed as input signal.Circuit shown in Figure 1 is for adopting by bipolar transistor (Bipolar JunctionTransistor, be called for short BJT, as Fig. 1 101 shown in) current mirror (the Current Mirror that gets up of two tandems being formed, as Fig. 1 102 and 103 shown in), utilize electric current I m1, the Im2 of these two current mirrors 102 and 103 and the mode that Ic three can be equal to each other, force the magnitude of current of control light emitting diode string 104.Therefore, use above-mentioned technology in circuit, can force the magnitude of current of respectively organizing light emitting diode string to reach consistent, and then finish the control of brightness uniformity with multi-group light-emitting diode string.
Yet, this circuit is only for opening the control system in loop, also be that this circuit there is no any FEEDBACK CONTROL, therefore once the light emitting diode string in the system breaks down (for example a few light-emitting diodes in the light emitting diode string be short-circuited fault), or the error amount of total cut-in voltage of light emitting diode string when too big (for example because the temperature characterisitic of every light-emitting diode is slightly different, it is poor to cause each light emitting diode string to form bigger total cut-in voltage in the energising back), because system does not have FEEDBACK CONTROL, so can't detect this state, therefore will cause the bipolar transistor on the current mirror to afford sizable voltage and electric current, make the temperature of bipolar transistor constantly rise, and then make bipolar transistor that overheated risk be arranged, thereby make the product of this technology of utilization have the doubt of Reliability.
In addition, such as No. the 6556067th, United States Patent (USP) and No. 6636104 patents, owing to also be to adopt this control mode of opening the loop of current mirror to force the magnitude of current of respectively organizing light emitting diode string to reach consistent, and then finish the control of brightness uniformity, therefore the doubt of Reliability is equally also arranged.
Summary of the invention
Purpose of the present invention just provides a kind of current control device, and it utilizes FEEDBACK CONTROL adjustment to flow through the electric current of light-emitting component string, and then reaches the purpose of adjusting light emitting diode string brightness, and has the Reliability of height.
Based on above-mentioned and other purpose, the present invention proposes a kind of current control device, is suitable for controlling the electric current of light-emitting component string, and wherein a wherein end of light-emitting component string electrically connects supply voltage, and this current control device comprises current adjustment unit and control unit.Current adjustment unit is electrically connected between the other end and earthed voltage of light-emitting component string, in order to detect the electric current of light-emitting component string, produce feedback signal according to this, and remove to control resistance value between light-emitting component string and the earthed voltage, and then the electric current of control light-emitting component string according to conducting control signal and impedance control signal.Wherein current adjustment unit comprises MOS transistor (full name is metal oxide semiconductor transistor, Metal-Oxide Semiconductor transistor), variable impedance apparatus and feedback unit.A wherein source/drain electrode of MOS transistor is electrically connected to the other end of light-emitting component string, and MOS transistor operates in linear zone.Variable impedance apparatus is electrically connected between the grid of control unit and MOS transistor, in order to transmit the grid that conducting controls signal to MOS transistor, and dynamically adjust the resistance value of variable impedance apparatus according to impedance control signal, so that MOS transistor changes conducting state according to the resistance value of conducting control signal and variable impedance apparatus, and then the resistance value when adjusting the MOS transistor conducting.Feedback unit is electrically connected between another source/drain electrode and earthed voltage of MOS transistor, in order to the electric current of detection light-emitting component string, and produces feedback signal according to this.Control unit is electrically connected to current adjustment unit, value in order to reception and comparison reference signal and feedback signal, producing comparative result, and comparative result is done current compensation, and the comparative result that will finish behind the current compensation converts conducting control signal and impedance control signal to.Wherein control unit also comprises error amplifier, current compensator and impedance controller.Error amplifier is electrically connected to current adjustment unit, and the value in order to reception and comparison reference signal and feedback signal produces comparative result according to this.Current compensator is electrically connected to error amplifier, in order to the reception comparative result, and exports after comparative result is done current compensation.Impedance controller is electrically connected to current compensator, in order to the output of received current compensator, and converts the output of current compensator to conducting control signal and impedance control signal.
Described according to one embodiment of the invention, above-mentioned control unit also comprises the driving buffer.Wherein drive buffer and be electrically connected to impedance controller, in order to receiving the conducting control signal, and after buffering conducting control signal with its output.
Described according to one embodiment of the invention, above-mentioned current adjustment unit also comprises first resistance, first electric capacity, second electric capacity and diode.Wherein first resistance is electrically connected between the other end and first electric capacity of light-emitting component string.First electric capacity is electrically connected between the grid of first resistance and MOS transistor.Second electric capacity is electrically connected between the grid and earthed voltage of MOS transistor.The anode of diode electrically connects the grid of MOS transistor, and the negative electrode of diode electrically connects the conducting control signal.
Based on above-mentioned and other purpose, the present invention proposes a kind of current control device, be suitable for controlling the electric current of a plurality of light-emitting component strings, a wherein end of wherein above-mentioned a plurality of light-emitting component strings electrically connects supply voltage, and this current control device comprises current adjustment unit group and control unit.The current adjustment unit group is electrically connected between the other end and earthed voltage of above-mentioned a plurality of light-emitting component strings, in order to detect the electric current of each light-emitting component string, produces a plurality of feedback signals according to this.The current adjustment unit group also receives a plurality of conducting control signals and a plurality of impedance control signal, and according to above-mentioned conducting control signal one of them and above-mentioned impedance control signal one of them removes to control the resistance value between above-mentioned light-emitting component string one of them and the earthed voltage, and then control the electric current that flows through of this light-emitting component string.Wherein above-mentioned current adjustment unit group comprises a plurality of current adjustment units, and each current adjustment unit comprises MOS transistor, variable impedance apparatus and feedback unit.A wherein source/drain electrode of MOS transistor is electrically connected to one of them the other end of above-mentioned a plurality of light-emitting component string, and MOS transistor operates in linear zone.Variable impedance apparatus is electrically connected between the grid of control unit and MOS transistor, in order to transmit above-mentioned one of them grid of a plurality of conducting control signal to MOS transistor, and according to above-mentioned a plurality of impedance control signals one of them and dynamically adjust the resistance value of variable impedance apparatus, so that this MOS transistor changes conducting state according to the resistance value of this conducting control signal and variable impedance apparatus, and then the resistance value when adjusting the MOS transistor conducting.Feedback unit is electrically connected between another source/drain electrode and earthed voltage of MOS transistor, in order to detecting the electric current of this light-emitting component string, and produce according to this above-mentioned a plurality of feedback signal one of them.
Control unit is electrically connected to the current adjustment unit group, in order to receive reference signal and above-mentioned a plurality of feedback signal, and the value of each feedback signal of comparison and reference signal, to produce a plurality of comparative results, and each comparative result is done current compensation, and those comparative results that will finish behind the current compensation convert above-mentioned a plurality of conducting control signal and a plurality of impedance control signal to.Wherein control unit comprises error amplifier, current compensator and impedance controller.Error amplifier is electrically connected to the current adjustment unit group, in order to receiving above-mentioned reference signal and above-mentioned a plurality of feedback signal, and the value of each feedback signal and above-mentioned reference signal relatively, to produce above-mentioned a plurality of comparative result.Current compensator is electrically connected to error amplifier, in order to receiving above-mentioned a plurality of comparative result, and output respectively after each comparative result is done current compensation.Impedance controller is electrically connected to current compensator, in order to those outputs of received current compensator, and converts those outputs of current compensator to above-mentioned a plurality of conducting control signal and a plurality of impedance control signal.
Described according to one embodiment of the invention, above-mentioned control unit also comprises the driving buffer.Wherein drive buffer and be electrically connected to impedance controller, in order to receiving above-mentioned a plurality of conducting control signal, and output respectively after the above-mentioned a plurality of conducting control signals of buffering.
Described according to one embodiment of the invention, each current adjustment unit also comprises first resistance, first electric capacity, second electric capacity and diode.Wherein first resistance is electrically connected between the other end and first electric capacity of this light-emitting component string.First electric capacity is electrically connected between the grid of first resistance and MOS transistor.Second electric capacity is electrically connected between the grid and earthed voltage of MOS transistor.The anode of diode electrically connects the grid of MOS transistor, and the negative electrode of diode electrically connects this conducting control signal.
The present invention carries out FEEDBACK CONTROL because of the electric current that utilizes the light-emitting component string, and the electric current of light-emitting component string carried out current compensation, and then the signal of the resistance value (channel sized when also controlling the MOS transistor conducting) when converting the result behind the current compensation to two kinds of control MOS transistor conductings, resistance value when changing the MOS transistor conducting according to this and adjust the electric current that flows through the light-emitting component string, and then reach the purpose of adjusting light emitting diode string brightness, so the present invention has than adopting this existing brightness regulating circuit of opening the circuit controls mode of current mirror that better Reliability is arranged.
For above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, preferred embodiment cited below particularly, and cooperate appended graphicly, be described in detail below.
Description of drawings
Fig. 1 is existing brightness regulating circuit.
Fig. 2 is the current control device according to one embodiment of the invention.
Fig. 3 is the partial circuit figure of Fig. 2.
Fig. 4 is the performance diagram of MOS transistor.
Fig. 5 is the current control device according to another embodiment of the present invention.
Embodiment
Fig. 2 is the current control device according to one embodiment of the invention.Please refer to Fig. 2, this current control device is suitable for the electric current I n that control flows is crossed light-emitting component string 210, in this embodiment, light-emitting component string 210 is made up of light-emitting diode 211,212～N, and a wherein end of light-emitting component string 210 is electrically connected to supply voltage VLED (i.e. first current potential).Yet light-emitting component string 210 also non-limitingly is made up of light-emitting diode.
This current control device comprises current adjustment unit 220 and control unit 230.Current adjustment unit 220 is in order to detect the electric current I n of light-emitting component string 210, and produce feedback signal FS according to this, and remove to control resistance value between light-emitting component string 210 and the earthed voltage GND (i.e. second current potential), and then the electric current I n of control light-emitting component string 210 according to conducting control signal CCS and impedance control signal ICS.Control unit 230 is in order to receive reference signal Vref and feedback signal FS, and the two value of comparison reference signal Vref and feedback signal FS, to produce comparative result CS, then again comparative result CS is done current compensation, the comparative result CS that will finish then behind the current compensation converts conducting control signal CCS and impedance control signal ICS to.
Above-mentioned driving buffer 234 mainly is a usefulness of the conducting control signal CCS that impedance controller 233 is exported being done signal damping and signal amplification, so the user can select whether to adopt driving buffer 234 according to actual needs in control unit 230.
Variable impedance apparatus is in order to the conducting control signal CCS that transmit to drive buffer 234 and the exported grid to MOS transistor, and dynamically adjust the resistance value of variable impedance apparatus 222 according to the impedance control signal that impedance controller 233 is exported, so that MOS transistor 221 changes conducting state according to the resistance value of conducting control signal CCS and variable impedance apparatus 222, and then the resistance value when adjusting MOS transistor 221 conductings, also promptly adjust the channel sized of MOS transistor 221.In other words,, just can the electric current I n of light-emitting component string 210 be controlled, and then adjust the brightness of light-emitting component string 210 by adjusting the channel sized of MOS transistor 221.
Fig. 3 is the partial circuit figure of Fig. 2.Fig. 4 is the performance diagram of MOS transistor.Below will conducting control signal CCS and the impedance control signal ICS control mode to the current adjustment unit 220 of Fig. 2 be described with Fig. 3 and Fig. 4.Please according to the explanation needs and with reference to Fig. 3 and Fig. 4.Please earlier with reference to Fig. 3, Rg in the current adjustment unit 220 of Fig. 3 is the resistance value of variable impedance apparatus 222, Ig is the current value that flows through variable impedance apparatus 222, Vg is variable impedance apparatus 222 and the magnitude of voltage that drives buffer 234 electric connections place, Vplt is the magnitude of voltage of variable impedance apparatus 222 and MOS transistor 221 electric connections place, Cgd and Cgs are respectively first electric capacity 225 of Fig. 2 and the capacitance of second electric capacity 226, Rgd is the resistance value of first resistance 224 of Fig. 2, Icgd is the current value that flows through first resistance 224, Vds then is the drain electrode of MOS transistor 221 and the magnitude of voltage between the source electrode, and Vled
1, Vled
2～Vled
NThen be respectively the light-emitting diode 211 of Fig. 2, the magnitude of voltage on 212～N.According to shown in Figure 3, can put out following 6 formulas in order:
Ig×Rg＝Vg-Vplt ......(1)
Icgd＝Cgd(dVds/dt) ......(3)
dVds/dt＝(Vg-Vplt)/(Rg×Cgd) ......(4)
Vds＝((Vg-Vplt)/(Rg×Cgd))t ......(5)
VLED＝(Vled
1+Vled
2+...+Vled
N)+Vds ......(6)
Can know that by formula (5) the big I of Vds is decided by the value of Rg and t.Please refer to Fig. 4, after MOS transistor entered linear zone, voltage Vds presented linear change, and electric current I n then presents fixed value.Referring again to Fig. 3.Therefore, when MOS transistor 221 operates in linear zone, just utilize the value of conducting control signal CCS modulation t, and the value of utilizing impedance control signal ICS modulation Rg, impedance magnitude in the time of so just can changing MOS transistor 221 conductings, also promptly change the channel sized of MOS transistor, use control Vds magnitude of voltage, and the value of the Vds that is obtained just can be used for compensating (the Vled that is caused because of the light-emitting diodes tube short circuit or because of the temperature characterisitic difference of light-emitting diode
1+ Vled
2+ ...+Vled
N) change, and then make the electric current I n of light-emitting component string 210 obtain control.
Haveing the knack of this skill person can be according to spirit of the present invention, and the teaching of the foregoing description, and a plurality of light-emitting component strings is carried out the control of electric current, one of them example that is shown in Figure 5.
Fig. 5 is the current control device according to another embodiment of the present invention.Please refer to Fig. 5.Current control device shown in Figure 5 is suitable for the electric current that control flows is crossed light-emitting component string 510,520 and 530, is respectively I
1, I
2, and I
3And I shown in Figure 5 is expressed as I
1, I
2, and I
3The total current of adding up mutually also is total drive current of light-emitting component string 510,520 and 530.In this embodiment, light-emitting component string 510,520 and 530 also is made up of light-emitting diode, and a wherein end of light-emitting component string 510,520 and 530 is electrically connected to supply voltage VLED (i.e. first current potential).Yet light-emitting component string 510,520 and 530 is also also non-limiting to be made up of light-emitting diode.
This current control device comprises current adjustment unit group 540 and control unit 550.Wherein current adjustment unit group 540 produces feedback signal FS respectively according to this in order to detect the electric current of light-emitting component string 510,520 and 530
1, FS
2, and FS
3And current adjustment unit group 540 also receives three conducting control signals, is respectively CCS
1, CCS
2With CCS
3, and receive three impedance control signals, be respectively ICS
1, ICS
2With ICS
3
Current adjustment unit group 540 is according to conducting control signal CCS
1With impedance control signal ICS
1Remove to control the resistance value between light-emitting component string 510 and the earthed voltage GND (i.e. second current potential), and according to conducting control signal CCS
2With impedance control signal ICS
2Remove to control the resistance value between light-emitting component string 520 and the earthed voltage GND, and according to conducting control signal CCS
3With impedance control signal ICS
3Remove to control the resistance value between light-emitting component string 530 and the earthed voltage GND.Thus, current adjustment unit group 540 just can be controlled the electric current that flows through of light-emitting component string 510,520 and 530 respectively.
As the described embodiment of Fig. 2, above-mentioned driving buffer 554 also is to be used for conducting control signal CCS that impedance controller 553 is exported
1, CCS
2With CCS
3Do the usefulness of signal damping and signal amplification respectively, so the user still can select whether to adopt driving buffer 554 according to actual needs in control unit 550.
Comprise 3 current adjustment units in the above-mentioned current adjustment unit group 540, be respectively 541,542 and 543, and the design architecture of each current adjustment unit is identical with current adjustment unit shown in Figure 2 220, therefore repeats no more the indoor design and the manner of execution of current adjustment unit 541,542 and 543.
Thus, just can be respectively to the electric current I of light-emitting component string 510,520 and 530
1, I
2, and I
3Control, reach the purpose of the brightness of adjusting above-mentioned light-emitting component string, and can make light-emitting component string 510,520 and 530 threes' brightness reach even further.Yet, above-mentioned current control device is not limited only to adjust the electric current of three light-emitting component strings, haveing the knack of this skill person ought can adjust the number of the current adjustment unit in the current adjustment unit group 540 along with the number of light-emitting component string, and adjusts error amplifier 551, current compensator 552, impedance controller 553 accordingly and drive the input of buffer 554 and the number of output.
What deserves to be mentioned is, though in the various embodiments described above, the internal circuit of current adjustment unit has been depicted a possible kenel, but knowing this operator should know, each manufacturer is all different for the design of current adjustment unit, and therefore application of the present invention is when being not restricted to the possible kenel of this kind.In other words, so long as utilize transistor, for example utilize MOS transistor, bipolar transistor or insulated gate electrode two-carrier transistor (InsulatedGate Bipolar Transistor, the variable characteristic of channel sized abbreviation IGBT), and make transistor operate in linear zone, and adjust transistorized channel sized according to inputing to the signal of current adjustment unit, and then the electric current of control light-emitting component string, be the spiritual place that has met current adjustment unit of the present invention just.
In sum, the present invention carries out FEEDBACK CONTROL because of the electric current that utilizes light emitting diode string, and the electric current of light emitting diode string carried out current compensation, and then the signal of resistance value when converting the result behind the current compensation to two kinds of control MOS transistor conductings, resistance value when changing the MOS transistor conducting according to this and adjust the electric current that flows through light emitting diode string, and then reach the purpose of the brightness of adjusting light emitting diode string, so the present invention has than adopting this existing brightness regulating circuit of opening the circuit controls mode of current mirror that better Reliability is arranged.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limiting the present invention, anyly has the knack of this skill person, without departing from the spirit and scope of the present invention; when can doing a little change and retouching, so protection scope of the present invention is when with being as the criterion that claim was defined.
Claims (22)
1. current control device is suitable for controlling the electric current of a light-emitting component string, and wherein a wherein end of this light-emitting component string electrically connects one first current potential, and this current control device comprises:
One current adjustment unit, be electrically connected between the other end and one second current potential of this light-emitting component string, in order to detect the electric current of this light-emitting component string, produce a feedback signal according to this, and remove to control resistance value between this light-emitting component string and this second current potential according to a conducting control signal and an impedance control signal, and then control the electric current of this light-emitting component string, wherein this current adjustment unit comprises:
One MOS transistor, a wherein source/drain electrode of this MOS transistor is electrically connected to the other end of this light-emitting component string;
One variable impedance apparatus, be electrically connected between the grid of a control unit and this MOS transistor, in order to transmit the grid that this conducting controls signal to this MOS transistor, and dynamically adjust the resistance value of this variable impedance apparatus according to this impedance control signal, so that this MOS transistor changes conducting state according to the resistance value of this conducting control signal and this variable impedance apparatus, and then the resistance value when adjusting this MOS transistor conducting; And
One feedback unit is electrically connected between another source/drain electrode and this second current potential of this MOS transistor, in order to detecting the electric current of this light-emitting component string, and produces this feedback signal according to this; And
This control unit, be electrically connected to this current adjustment unit, in order to receive and to compare the value of a reference signal and this feedback signal, to produce a comparative result, and this comparative result is done current compensation, and this comparative result that will finish behind the current compensation converts this conducting control signal and this impedance control signal to, and wherein this control unit comprises:
One error amplifier is electrically connected to this current adjustment unit, in order to receive and the value of this reference signal and this feedback signal relatively, produces this comparative result according to this;
One current compensator is electrically connected to this error amplifier, in order to receiving this comparative result, and exports after this comparative result is done current compensation; And
One impedance controller is electrically connected to this current compensator, in order to receiving the output of this current compensator, and converts the output of this current compensator to this conducting control signal and this impedance control signal.
2. current control device as claimed in claim 1 is characterized in that, this control unit also comprises:
One drives buffer, is electrically connected to this impedance controller, in order to receiving this conducting control signal, and after this conducting control signal of buffering with its output.
3. current control device as claimed in claim 1 is characterized in that, this MOS transistor is a nmos pass transistor, and this MOS transistor operates in linear zone.
4. current control device as claimed in claim 3 is characterized in that, this current adjustment unit also comprises:
One first resistance, this first resistance are electrically connected between the grid of the other end of this light-emitting component string and this MOS transistor.
5. current control device as claimed in claim 4 is characterized in that, this current adjustment unit also comprises:
One first electric capacity, this first electric capacity is electrically connected between the grid of this first resistance and this MOS transistor.
6. current control device as claimed in claim 5 is characterized in that, this current adjustment unit also comprises:
One second electric capacity, this second electric capacity are electrically connected between the grid and this second current potential of this MOS transistor.
7. current control device as claimed in claim 6 is characterized in that, this feedback unit comprises one second resistance, and this second resistance is electrically connected between another source/drain electrode and this second current potential of this MOS transistor.
8. current control device as claimed in claim 7 is characterized in that, this first current potential is a supply voltage.
9. current control device as claimed in claim 8 is characterized in that, this second current potential is an earthed voltage.
10. current control device as claimed in claim 1 is characterized in that, this current adjustment unit also comprises:
One diode, the anode of this diode electrically connects the grid of this MOS transistor, and the negative electrode of this diode electrically connects this conducting control signal.
11. current control device as claimed in claim 1 is characterized in that, this light-emitting component string is made up of a plurality of light-emitting diode.
12. a current control device is suitable for controlling the electric current that flows through of a plurality of light-emitting component strings, it is characterized in that a wherein end of those light-emitting component strings electrically connects one first current potential, this current control device comprises:
One current adjustment unit group, be electrically connected between the other end and one second current potential of those light-emitting component strings, in order to detect the electric current of each light-emitting component string, produce a plurality of feedback signals according to this, this current adjustment unit group also receives a plurality of conducting control signals and a plurality of impedance control signal, and according to a plurality of conducting control signals one of them and a plurality of impedance control signal one of them removes to control the resistance value between those light-emitting component strings one of them and this second current potential, and then control the electric current that flows through of this light-emitting component string, wherein this current adjustment unit group comprises a plurality of current adjustment units, and each current adjustment unit comprises:
One MOS transistor, a wherein source/drain electrode of this MOS transistor are electrically connected to one of them the other end of those light-emitting component strings;
One variable impedance apparatus, be electrically connected between the grid of a control unit and this MOS transistor, in order to transmit one of them grid of those conducting control signals to this MOS transistor, and according to those impedance control signals one of them and dynamically adjust the resistance value of this variable impedance apparatus, so that this MOS transistor changes conducting state according to the resistance value of this conducting control signal and this variable impedance apparatus, and then the resistance value when adjusting this MOS transistor conducting; And
One feedback unit is electrically connected between another source/drain electrode and this second current potential of this MOS transistor, in order to detecting one of them electric current of those light-emitting component strings, and produce according to this those feedback signals one of them; And
This control unit, be electrically connected to this current adjustment unit group, in order to receive a reference signal and those feedback signals, and the value of each feedback signal of comparison and this reference signal, to produce a plurality of comparative results, and each comparative result is done current compensation, and those comparative results that will finish behind the current compensation convert those conducting control signals and those impedance control signals to, wherein this control unit comprises:
One error amplifier is electrically connected to this current adjustment unit group, in order to receiving this reference signal and those feedback signals, and the value of each feedback signal and this reference signal relatively, to produce those comparative results;
One current compensator is electrically connected to this error amplifier, in order to receiving those comparative results, and output respectively after each comparative result is done current compensation; And
One impedance controller is electrically connected to this current compensator, in order to receiving those outputs of this current compensator, and converts those outputs of this current compensator to those conducting control signals and those impedance control signals.
13. current control device as claimed in claim 12 is characterized in that, this control unit also comprises:
One drives buffer, is electrically connected to this impedance controller, in order to receiving those conducting control signals, and output respectively after those conducting control signals of buffering.
14. current control device as claimed in claim 12 is characterized in that, this MOS transistor is a nmos pass transistor, and this MOS transistor operates in linear zone.
15. current control device as claimed in claim 14 is characterized in that, each current adjustment unit also comprises:
One first resistance, this first resistance are electrically connected between one of them the other end and the grid of this MOS transistor of those light-emitting component strings.
16. current control device as claimed in claim 15 is characterized in that, each current adjustment unit also comprises:
One first electric capacity, this first electric capacity is electrically connected between the grid of this first resistance and this MOS transistor.
17. current control device as claimed in claim 16 is characterized in that, each current adjustment unit also comprises:
One second electric capacity, this second electric capacity are electrically connected between the grid and this second current potential of this MOS transistor.
18. current control device as claimed in claim 17 is characterized in that, this feedback unit comprises one second resistance, and this second resistance is electrically connected between another source/drain electrode and this second current potential of this MOS transistor.
19. current control device as claimed in claim 18 is characterized in that, this first current potential is a supply voltage.
20. current control device as claimed in claim 19 is characterized in that, this second current potential is an earthed voltage.
21. current control device as claimed in claim 12 is characterized in that, each current adjustment unit also comprises:
One diode, the anode of this diode electrically connects the grid of this MOS transistor, and the negative electrode of this diode electrically connects this conducting control signal.
22. current control device as claimed in claim 12 is characterized in that, each light-emitting component string is made up of a plurality of light-emitting diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100038583A CN100558207C (en) | 2007-01-09 | 2007-01-09 | Current control device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100038583A CN100558207C (en) | 2007-01-09 | 2007-01-09 | Current control device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101222801A CN101222801A (en) | 2008-07-16 |
| CN100558207C true CN100558207C (en) | 2009-11-04 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2007100038583A Expired - Fee Related CN100558207C (en) | 2007-01-09 | 2007-01-09 | Current control device |
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| CN (1) | CN100558207C (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI426816B (en) * | 2010-12-21 | 2014-02-11 | Au Optronics Corp | Driving power control circuit and method for light emitting diode |
| CN102708801A (en) * | 2012-06-06 | 2012-10-03 | 天津三星电子有限公司 | Backlight brightness control method for display terminal and display terminal adopting same |
| CN102982771B (en) * | 2012-11-28 | 2016-01-13 | 深圳市华星光电技术有限公司 | A kind of backlight drive circuit and liquid crystal display |
| CN104242277B (en) * | 2013-06-21 | 2018-03-23 | 中国科学院微电子研究所 | A kind of device to loading or exporting progress current-limiting protection |
| JP6362996B2 (en) * | 2014-10-24 | 2018-07-25 | 株式会社日立製作所 | Semiconductor drive device and power conversion device using the same |
| KR101856335B1 (en) * | 2016-06-30 | 2018-05-09 | 현대자동차주식회사 | IGBT Temperature Sense Circuit for Calibrating Automatically Diode Temperature |
-
2007
- 2007-01-09 CN CNB2007100038583A patent/CN100558207C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN101222801A (en) | 2008-07-16 |
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