CN102938952A - Current setting circuit of a plurality of light-emitting diode (LED) strings and method thereof - Google Patents
Current setting circuit of a plurality of light-emitting diode (LED) strings and method thereof Download PDFInfo
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- CN102938952A CN102938952A CN2012102499000A CN201210249900A CN102938952A CN 102938952 A CN102938952 A CN 102938952A CN 2012102499000 A CN2012102499000 A CN 2012102499000A CN 201210249900 A CN201210249900 A CN 201210249900A CN 102938952 A CN102938952 A CN 102938952A
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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
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
Abstract
The invention discloses a current setting circuit of a plurality of light-emitting diode (LED) strings and a method thereof. The circuit comprises a current generation circuit, a current mirror with a plurality of output ends and used for receiving current generated by the current generation circuit and a selection switching module. The selection switching module conducts one-to-one communication between the output ends of the current mirror and the LED strings and switches the one-to-one communication in non-repeated mode to enable each LED string to conduct one-to-one communication with the output ends of the current mirror in set time. The circuit can achieve the effect that the LED string have identical current and further achieves even brightness of an LED lamp.
Description
Technical field
The present invention relates to the control technology field of LED lamp brightness, more particularly, relate to a kind of current setting circuit and method of a plurality of LED strings.
Background technology
At present, along with the development of semiconductor technology, the range of application of LED lamp is also more and more wider.Usually each LED lamp is comprised of a plurality of LED connection in series-parallel, and each LED string links to each other with one of them output of current mirror respectively, to obtain drive current.
But because there is drift in semiconductor technology, will there be mismatch in the semiconductor device of each output of current mirror.Therefore, the electric current of each output of current mirror will be not identical, and the electric current that obtains between each LED that links to each other with each output of current mirror gangs up is not identical yet.
Because it is different that LED goes here and there the electric current that each passage obtains, therefore can cause the brightness irregularities of each LED lamp.
Summary of the invention
In view of this, the invention provides a kind of current setting circuit and method of a plurality of LED strings, identical with the drive current of realizing each LED string acquisition, and then realize that the brightness of LED lamp is even.
For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of current setting circuit of a plurality of LED string comprises: current generating circuit, have a plurality of outputs and receive the current mirror of described current generating circuit generation current and select handover module; Wherein:
Described selection handover module is communicated with between the output of described current mirror and LED string one to one, and in setting-up time described the connection one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror in this setting-up time.
Preferably, described selection handover module comprises control circuit and a plurality of MUX:
Described control circuit is used for generating real-time control signal, and described real-time control signal is sent to the MUX that each links to each other with described control circuit;
Each described MUX has the input identical with current mirror output quantity and both are communicated with one to one; Between each MUX, each input is not identical with the one to one connection between the current mirror output simultaneously.
Preferably, described control circuit comprises the pulse generator sum counter; Wherein:
The input of described counter links to each other with described pulse generator, and output links to each other with described MUX, is used for the clock pulse that described pulse generator produces is counted, and exports described control signal according to the counting order.
Preferably, described circuit also comprises the current multiplication circuit that is connected between described selection handover module and the LED string.
Preferably, describedly in setting-up time, described the connection one to one carried out unduplicated switching and carry out according to setpoint frequency.
Preferably, described setpoint frequency is the frequency that judges faster than human eye.
A kind of current settings method of a plurality of LED strings, the current setting circuit that is used for a plurality of LED strings, described current setting circuit comprises current generating circuit at least, and have a plurality of outputs and receive the current mirror of described current generating circuit generation current, wherein the output quantity of current mirror is identical with LED string quantity, and the method comprises:
The LED string is communicated with one to one with the output of current mirror, and in setting-up time, described the connection is one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror in this setting-up time;
Repeating the interior LED string of described setting-up time is communicated with the man-to-man switching of current mirror output.
Preferably, described method also comprises after output current with current mirror doubles and is sent to the LED string.
Preferably, describedly in setting-up time, described the connection one to one carried out unduplicated switching and carry out according to setpoint frequency.
Preferably, described setpoint frequency is the frequency that judges faster than human eye.
Can find out from above-mentioned technical scheme, current setting circuit and the method for a kind of a plurality of LED strings disclosed by the invention, by select handover module the output of current mirror be communicated with one to one between LED goes here and there, and in setting-up time, described the connection one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror in this setting-up time, realized that the electric current that each LED string obtains is the mean value of all output end currents of current mirror within the time of setting, and then realized that the brightness of the LED lamp that is comprised of a plurality of LED strings is even.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, the below will do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art, apparently, accompanying drawing in the following describes only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the structural representation of the current setting circuit of the disclosed a kind of a plurality of LED strings of the embodiment of the invention;
Fig. 2 is the structural representation of the current setting circuit of the disclosed a kind of a plurality of LED strings of another embodiment of the present invention;
Fig. 3 is the flow chart of the current settings method of a kind of a plurality of LED strings disclosed by the invention;
Fig. 4 is the circuit diagram of the current setting circuit of disclosed a kind of 16 LED string of prior art;
Fig. 5 is the circuit diagram of the current setting circuit of disclosed a kind of 16 LED string of another embodiment of the present invention;
Fig. 6 is a kind of realization circuit diagram of 16 tunnel MUX disclosed by the invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is a part of embodiment of the present invention, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that obtains under the creative work prerequisite.
The embodiment of the invention discloses a kind of current setting circuit and method of a plurality of LED strings, identical with the drive current of realizing each LED string acquisition, and then realize that the brightness of LED lamp is even.
As shown in Figure 1, a kind of current setting circuit of a plurality of LED string comprises: current generating circuit 11, have a plurality of outputs and receive the current mirror 12 of described current generating circuit generation current and select handover module 13; Wherein:
Select handover module 13 the output of current mirror 12 be communicated with one to one between LED goes here and there, and in setting-up time described the connection one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror 12 in this setting-up time.
Concrete, in setting-up time unduplicated switching being carried out in described one to one connection is to carry out according to the frequency that judges faster than human eye.
Concrete, select handover module 13 to comprise control circuit and MUX;
Control circuit is used for generating real-time control signal, and described real-time control signal is sent to the MUX that each links to each other with described control circuit;
Each MUX has the input identical with current mirror 12 output quantity and both are communicated with one to one; Between each MUX, each input is not identical with the one to one connection between current mirror 12 outputs simultaneously.
Concrete, control circuit comprises the pulse generator sum counter; Wherein:
The input of counter links to each other with pulse generator, and output links to each other with MUX, and the clock pulse that is used for the generation of paired pulses generator is counted, and according to counting order output control signal.
In the above-described embodiments, by select handover module 13 the output of current mirror 12 be communicated with one to one between LED goes here and there, and in setting-up time, described the connection one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror in this setting-up time, realized that the electric current that each LED string obtains is the mean value of all output end currents of current mirror within the time of setting, and then realized that the brightness of the LED lamp that is comprised of a plurality of LED strings is even.
Another embodiment of the present invention also discloses a kind of current setting circuit of a plurality of LED strings, as shown in Figure 2, comprising:
Select handover module 23 the output of current mirror 22 be communicated with one to one between LED goes here and there, and in setting-up time described the connection one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror 22 in this setting-up time;
Current multiplication circuit 24 is connected in to be selected between handover module 23 and the LED string, is used for offering the LED string behind the current multiplication with current mirror 22 outputs.
As shown in Figure 3, a kind of current settings method of a plurality of LED strings comprises:
S101, LED string is communicated with one to one with the output of current mirror, and in setting-up time described the connection one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of all current mirrors in this setting-up time;
S102, repeat that the LED string is communicated with the man-to-man switching of current mirror output in the described setting-up time.
Concrete, be sent to the LED string after the output current of current mirror can also being doubled;
In setting-up time unduplicated switching being carried out in described one to one connection is to carry out according to the frequency that judges faster than human eye.
For LED lamp current initialization circuit disclosed by the invention and method can more clearly be described, the circuit diagram of the circuit diagram of setting below in conjunction with 16 LED lamp string stream in the prior art and the current settings of 16 LED string disclosed by the invention is described in detail.
As shown in Figure 4, be the circuit diagram of the current settings of 16 LED strings in the prior art, by 16 LED strings are connected on one of them output of current mirror, to obtain the electric current of this output.
The electric current of current mirror output is provided by following formula:
Wherein:
The percentage error that ε 2 causes for metal-oxide-semiconductor dimensional mismatch in the current mirror and channel modulation effect;
The error that ε 4 causes for resistance mismatch.
Owing to can reduce by wave chopping technology in the prior art the imbalance of operational amplifier, so that ε 1 and ε 3 remain on below 0.5%, ε is remained on below 0.5%, so the electric current of current mirror output can be:
This shows that the current error of current mirror output is mainly caused by the percentage error ε 2 that metal-oxide-semiconductor dimensional mismatch in the current mirror and channel modulation effect cause.
Because the current error of each output of current mirror that metal-oxide-semiconductor dimensional mismatch and channel modulation effect cause in the current mirror, another embodiment of the present invention discloses the circuit diagram of the current setting circuit of 16 LED strings in order to solve.
As shown in Figure 5, the input by counter links to each other with the output of pulse generator, and output links to each other with each 16 tunnel MUX, each counter and 16 tunnel MUX implementation as shown in Figure 6; As shown in Figure 5, first input of first MUX is connected with first output of current mirror, second input of this MUX is connected with second output of current mirror, goes down successively, and the 16th input of this MUX is connected with the 16th output of current mirror; First input of second MUX is connected with second output of current mirror, second input of this MUX is connected with the 3rd output of current mirror, go down successively, the 16th input of this MUX is connected with first output of current mirror.According to such rule: between each MUX, each input is not identical with the one to one connection between the current mirror output.
Certainly, in other embodiments, also can be that each MUX is the same with the output connected mode of current mirror, namely all be: first input of first MUX is connected with first output of current mirror, second input of this MUX is connected with second output of current mirror, goes down successively; Second also is like this.And " in setting-up time, described the connection one to one being carried out unduplicated switching; so that each LED string carried out being communicated with one to one with the output of all current mirrors in this setting-up time ", these MUX inputs then rely on the control signal of these MUX outputs of control to finish, as long as can realize the control signal of above-mentioned functions.
The counter clock pulse that the paired pulses generator produces in one-period is counted, and according to 16 different control signals of counting order generation, each different control signal is controlled one of them output of 16 tunnel MUX making current mirrors, and the relation between the output of the output of counter and No. 16 selectors is as shown in table 1;
Relation between the output of the output of table 1 counter and No. 16 selectors
| Q0 | Q1 | Q2 | Q3 | Multichannel is selected output |
| 0 | 0 | 0 | 0 | 1 |
| 1 | 0 | 0 | 0 | 2 |
| 0 | 1 | 0 | 0 | 3 |
| 1 | 1 | 0 | 0 | 4 |
| 0 | 0 | 1 | 0 | 5 |
| 1 | 0 | 1 | 0 | 6 |
| 0 | 1 | 1 | 0 | 7 |
| 1 | 1 | 1 | 0 | 8 |
| 0 | 0 | 0 | 1 | 9 |
| 1 | 0 | 0 | 1 | 10 |
| 0 | 1 | 0 | 1 | 11 |
| 1 | 1 | 0 | 1 | 12 |
| 0 | 0 | 1 | 1 | 13 |
| 1 | 0 | 1 | 1 | 14 |
| 0 | 1 | 1 | 1 | 15 |
| 1 | 1 | 1 | 1 | 16 |
| 0 | 0 | 0 | 0 | 1 |
In one-period, 16 LED strings evenly switch between 0 ~ 16 road output of current mirror, and therefore, the drive current that each LED string obtains in one-period is:
Because the switch speed of MUX after receiving control signal be very fast at every turn, human eye has filter function, can not discover the difference of the LED lamp brightness that the electric current moment conversion that each LED string brings, and has therefore realized that the brightness of LED lamp is even.
Each embodiment adopts the mode of going forward one by one to describe in this specification, and what each embodiment stressed is and the difference of other embodiment that identical similar part is mutually referring to getting final product between each embodiment.
To the above-mentioned explanation of the disclosed embodiments, make this area professional and technical personnel can realize or use the present invention.Multiple modification to these embodiment will be apparent concerning those skilled in the art, and General Principle as defined herein can in the situation that does not break away from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (10)
1. the current setting circuit of an a plurality of LED string is characterized in that, comprising: current generating circuit, have a plurality of outputs and receive the current mirror of described current generating circuit generation current and select handover module; Wherein:
Described selection handover module is communicated with between the output of described current mirror and LED string one to one, and in setting-up time described the connection one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror in this setting-up time.
2. circuit according to claim 1 is characterized in that, described selection handover module comprises control circuit and a plurality of MUX;
Described control circuit is used for generating real-time control signal, and described real-time control signal is sent to the MUX that each links to each other with described control circuit;
Each described MUX has the input identical with current mirror output quantity and both are communicated with one to one; Between each MUX, each input is not identical with the one to one connection between the current mirror output simultaneously.
3. circuit according to claim 2 is characterized in that, described control circuit comprises the pulse generator sum counter; Wherein:
The input of described counter links to each other with described pulse generator, and output links to each other with described MUX, is used for the clock pulse that described pulse generator produces is counted, and exports described control signal according to the counting order.
4. circuit according to claim 1 is characterized in that, also comprises the current multiplication circuit that is connected between described selection handover module and the LED string.
5. circuit according to claim 1 is characterized in that, describedly in setting-up time described the connection is one to one carried out unduplicated switching and carries out according to setpoint frequency.
6. circuit according to claim 5 is characterized in that, described setpoint frequency is the frequency that judges faster than human eye.
7. the current settings method of an a plurality of LED string, the current setting circuit that is used for a plurality of LED strings, described current setting circuit comprises current generating circuit at least, and have a plurality of outputs and receive the current mirror of described current generating circuit generation current, wherein the output quantity of current mirror is identical with LED string quantity, it is characterized in that the method comprises:
The LED string is communicated with one to one with the output of current mirror, and in setting-up time, described the connection is one to one carried out unduplicated switching, so that each LED string carried out being communicated with one to one with all outputs of current mirror in this setting-up time;
Repeating the interior LED string of described setting-up time is communicated with the man-to-man switching of current mirror output.
8. method according to claim 7 is characterized in that, also comprises after output current with current mirror doubles being sent to the LED string.
9. method according to claim 7 is characterized in that, describedly in setting-up time described the connection is one to one carried out unduplicated switching and carries out according to setpoint frequency.
10. method according to claim 9 is characterized in that, described setpoint frequency is the frequency that judges faster than human eye.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012102499000A CN102938952A (en) | 2012-07-18 | 2012-07-18 | Current setting circuit of a plurality of light-emitting diode (LED) strings and method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012102499000A CN102938952A (en) | 2012-07-18 | 2012-07-18 | Current setting circuit of a plurality of light-emitting diode (LED) strings and method thereof |
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|---|---|
| CN102938952A true CN102938952A (en) | 2013-02-20 |
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| CN2012102499000A Pending CN102938952A (en) | 2012-07-18 | 2012-07-18 | Current setting circuit of a plurality of light-emitting diode (LED) strings and method thereof |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070046660A1 (en) * | 2005-08-24 | 2007-03-01 | Sharp Kabushiki Kaisha | Power supply circuit and electronic appliance therewith |
| CN102455732A (en) * | 2010-11-03 | 2012-05-16 | 华润矽威科技（上海）有限公司 | Circuit capable of improving matching degree of multi-path large current |
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- 2012-07-18 CN CN2012102499000A patent/CN102938952A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070046660A1 (en) * | 2005-08-24 | 2007-03-01 | Sharp Kabushiki Kaisha | Power supply circuit and electronic appliance therewith |
| CN102455732A (en) * | 2010-11-03 | 2012-05-16 | 华润矽威科技（上海）有限公司 | Circuit capable of improving matching degree of multi-path large current |
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Application publication date: 20130220 |