CN100562911C - LED drive and use its display device - Google Patents
LED drive and use its display device Download PDFInfo
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- CN100562911C CN100562911C CNB2006101604042A CN200610160404A CN100562911C CN 100562911 C CN100562911 C CN 100562911C CN B2006101604042 A CNB2006101604042 A CN B2006101604042A CN 200610160404 A CN200610160404 A CN 200610160404A CN 100562911 C CN100562911 C CN 100562911C
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Abstract
A kind of LED drive and use its display device, this LED drive be in order to drive first group of light emitting diode and second group of light emitting diode, comprises inductance, main switch, first and second switch, and controller.One termination of inductance is received input voltage.Main switch is coupled between the other end and common electric potential of inductance, with the flow through electric current of inductance of adjusting.First switch is coupled between the other end of first group of light emitting diode and inductance.Second switch is coupled between the other end of second group of light emitting diode and inductance.Controller couples the control end of main switch, first and second switch respectively, in order to the conducting state of control main switch, first and second switch.
Description
Technical field
The present invention is relevant for a kind of driver of display, and particularly relevant for a kind of LED drive and use its display device.
Background technology
Many electronic products in recent years all have display screen, for example mobile phone, PDA (Personal Digital Assistant) (PDA:Personal digital assistant), digital music broadcasting machine and fascia.Though the kind of screen and size are normally according to using decision, but the design engineer is necessary for its design lighting circuit, all need back lighting because comprise Thin Film Transistor-LCD at interior most displays, the user just can see figure and the literal on the screen clearly like this.Light emitting diode is the normal lighting device that adopts of present electronic product.With 3～4 of the needs even backlight or the more light emitting diode of a chromatic liquid crystal screen curtain, the instrument panel backlight may need 6 or more light emitting diode.Because increasing of light emitting diode demand effectively promoted the growth in LED drive market.
Fig. 1 is known display device circuit diagram.Please refer to Fig. 1, known display device is used backlight module 100.Backlight module 100 comprises LED drive 110,120 and 130, also has color to be respectively red, green and blue light-emitting diode group 113,123 and 133.Three LED drive 110,120 and 130 circuit are all known boosting (boost) circuit as can be seen for we.Each light-emitting diode group is that the light emitting diode string joint group by a plurality of same colors closes and forms.A LED drive can only drive one group of light-emitting diode group.That is to say that a controller 117 can only be controlled a switch 112 and the loop that feedback circuit 115 is constituted.Therefore, boosting of LED drive 110 can only be carried out the drive controlling in single loop, controls single group of light-emitting diode group 113.
Above-mentioned three LED drive 110,120 and 130, their circuit structure is the same.Each LED drive 110,120 and 130 can both independent regulation input voltage VI, the light-emitting diode group 113,123 and 133 of dependence is had independently regulate electric current.With LED drive 110 is example, and it comprises that controller 117, main switch 116, inductance 111, switch 112, feedback circuit 115 and mu balanced circuit 114 form.
Suppose that desire drives the light-emitting diode group of three groups of different colours, because LED drive can only be controlled the driving of one group of light-emitting diode group, so three groups of light-emitting diode group just must be used three LED drive.It is different that each organizes the required pressure drop of color LEDs group again, and the sizes values of selecting inductance 111,121,131 is to determine according to each voltage of organizing the required driving of light-emitting diode group.
Need an independent LED drive circuit so will drive one group of light-emitting diode group with previous display device technology.The rest may be inferred, though we can find that this traditional approach design is very simple, designed led driver circuit area can follow driven for emitting lights diode group quantity to increase in proportion, and the multiple that required circuit area can be directly proportional increases.
The above analysis, previous LED drive technology major defect is that controller can only be controlled single loop, so each group light-emitting diode group needs the individual design LED drive, therefore required circuit area is big, make us when the application LED drive is come deisgn product, must think deeply several problems: the one, circuit area can have influence on small product size, and being in addition increases the incident circuit cost of LED drive institute to increase.Therefore, above-mentioned known technology can cause required circuit component quantity too much, and it is big to take circuit area, the complexity of circuit-board laying-out increases, add that the circuit volume becomes big, the flexibility ratio variation that LED drive is used, and cause the competitiveness of the electronic product that uses it to descend.
Summary of the invention
Purpose of the present invention is providing a kind of LED drive exactly, in order to save the circuit component requirement, reaches the effect that drives multi-group light-emitting diode.
A further object of the present invention provides a kind of display device, in order to common elements, reaches the effect that drives multi-group light-emitting diode, further increases the element service efficiency.
The present invention proposes a kind of LED drive, drives at least the first group, second group of light emitting diode.This LED drive comprises inductance, main switch, first and second switch and controller.One termination of inductance is received input voltage.Main switch is coupled between the other end and common electric potential of inductance, with the flow through electric current of inductance of adjusting.First switch is coupled between the other end of first group of light emitting diode and inductance.Second switch is coupled between the other end of second group of light emitting diode and inductance.Controller couples the control end of main switch, first and second switch respectively, in order to the conducting state of control main switch, first and second switch.
From another viewpoint, the present invention proposes a kind of display device, and this display device comprises backlight module.Backlight module comprises first group of light emitting diode, second group of light emitting diode, inductance, main switch, first and second switch and controller.One termination of inductance is received input voltage.Main switch is coupled between the other end and common electric potential of inductance, with the flow through electric current of inductance of adjusting.First switch is coupled between the other end of first group of light emitting diode and inductance.Second switch is coupled between the other end of second group of light emitting diode and inductance.Controller couples the control end of main switch, first and second switch respectively, in order to the conducting state of control main switch, first and second switch.
According to the described LED drive of preferred embodiment of the present invention and use its display device also to comprise first and second feedback circuit.First end of first feedback circuit couples first group of light emitting diode and controller, and its second end couples common electric potential.First end of second feedback circuit couples second group of light emitting diode and controller, and its second end couples common electric potential.Wherein, controller respectively according to the voltage of first end of first and second feedback circuit to control the ON time of first and second switch.
In a preferred embodiment, above-mentioned LED drive and use its display device, wherein common electric potential is an earthing potential, and main switch is the N transistor npn npn.
In a preferred embodiment, above-mentioned LED drive and use its display device also to comprise first and second mu balanced circuit.Wherein first mu balanced circuit is coupled between first end and common electric potential of first switch.Second mu balanced circuit is coupled between first end and common electric potential of second switch.
In a preferred embodiment, above-mentioned LED drive and use its display device, wherein the color difference of first group and second group light emitting diode.
In a preferred embodiment, above-mentioned LED drive and use its display device also to comprise the 3rd switch.First end of the 3rd switch couples the 3rd group of light emitting diode, and second end of the 3rd switch couples the other end of inductance, and the control end of the 3rd switch couples controller, and its middle controller is also in order to control the conducting state of the 3rd switch.
In a preferred embodiment, above-mentioned LED drive and use its display device, the color of wherein first group, second group and the 3rd group light emitting diode is respectively red, green and blue.
No matter the present invention drives several groups of light emitting diodes, all only need use a main switch, an inductance and a group controller.When therefore being applied to display device, when using LED drive as embodiments of the invention as backlight module, can save the cost that many backlight modules are used in circuit component significantly, and the complexity of volume, circuit cost and the circuit-board laying-out of minimizing display device, and then more increase the product competition advantage of using, also help Application Design on the portable consumption electronic product.
For above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, preferred embodiment cited below particularly, and conjunction with figs. are described in detail as follows.
Description of drawings
Fig. 1 is known display device circuit diagram.
Fig. 2 is a kind of display device circuit diagram of the embodiment of the invention.
Fig. 3 is the another kind of display device circuit diagram of the embodiment of the invention.
The main element symbol description
100,200,300: backlight module
110,120,130,210,310: LED drive
117,212,312: controller
116,126,136,213: main switch
111,121,131,211,311: inductance
112,122,132,221,231,341: switch
113,123,133,222,232,342: light-emitting diode group
114,223,233,343: mu balanced circuit
115,224,234,344: feedback circuit
214,314: output voltage
225,235: loop voltage
VI: input voltage
Embodiment
Because formerly in the display device technology, one group of light-emitting diode group of every driving just needs an independent LED drive circuit.When institute driven for emitting lights diode group number increased, the quantity of required LED drive also increased, and employed element also and then increases, thus the area of circuit component layout on circuit board also certainly will with increase.The present invention proposes a kind of LED drive, in order to save the circuit component requirement.Below just the present invention is described with embodiment.
Fig. 2 is a kind of display device circuit diagram in order to the explanation embodiment of the invention.At first please refer to Fig. 2, this display device comprises backlight module 200.Backlight module 200 comprises LED drive 210, light-emitting diode group 222 and 232.LED drive 210 comprise inductance 211, main switch 213, switch 221,231, controller 212, mu balanced circuit 223,233, with feedback circuit 224 and 234.
This backlight module 200 has two groups of light- emitting diode group 222 and 232, and light- emitting diode group 222 and 232 can all be the connecting of light emitting diode of same kind, also may be two kinds of light-emitting diode group.Use the light emitting diode of same kind,, can be used as the white backlight lamp source of display device as using the light emitting diode of white light.Different types of light-emitting diode group or with kind but series connection light emitting diode number difference, required driving voltage is also different, therefore, the controller 212 of LED drive 210, control two independent loops, respectively the output loop of the current potential that boosts of the different demands of gauge tap 221,231.
Because light- emitting diode group 222 and 232 is that a plurality of light emitting diode modes of connecting are formed.When each light emitting diode of electric current by on the same group the time, because of electric current is identical, can obtain uniform brightness.Again because in this embodiment light emitting diode is to have adopted a plurality of light emitting diode series connection modes to design, make the forward voltage drop addition of each light emitting diode, the voltage that light- emitting diode group 222 and 232 needs are higher just can be driven.Also have, suppose that LED drive 210 is to be applied to portable electronic apparatus, input voltage VI is a battery, connects from battery just to begin when circuit uses and can descend up to exhausting electric energy by voltage.So, the drive principle of LED drive 210, (boost) method of boosting of employing DC-DC.
Because light- emitting diode group 222 and 232 shared inductance 211, we are according to the required driving maximum voltage in two groups of light-emitting diode group, select the inductance 211 that rated output voltage 214 and more margin of safety scopes can be provided for use, so that make input voltage VI have broad suitable opereating specification to boost and can obtain greater efficiency when driving, and maintain good insulation and Electrical Safety.
The controller 212 that one planning able to programme is arranged in the LED drive 210, with programming timesharing, regulative mode in turn, one of them electric current of regulating two groups of light- emitting diode group 222 and 232 carries out the control of closed loop.That is to say that though two groups of light- emitting diode group 222 and 232 are arranged, 212 each conductings of controller are one group of light-emitting diode group wherein.Controller 212 is in order to keep regulating the electric current of light- emitting diode group 222 and 232, constantly alternately detect the loop voltage 225 between controller 212 and the feedback circuit 224, and the loop voltage 235 between detection controller 212 and the feedback circuit 234, the feedback of loop voltage 225 and 235 is input into the logical circuit of controller 212 inside, at control wherein the output voltage 214 of one group of light-emitting diode group regulate, and switch the ON time of main switch 213, switch 221 and 231 with the programming planning control, reach the adjustment output current.
In the design of FEEDBACK CONTROL, inner one or more reference voltages carry out error ratio to controller 212 with it according to loop voltage 225 or 235.If with the present embodiment is example, suppose that light- emitting diode group 222 and 232 is respectively a different colours, thereby forward voltage difference to some extent, driving voltage also needs difference, therefore under these conditions, controller 212 just needs corresponding feedback circuit 224 and 234 that two different reference voltages are provided respectively.When supposing loop voltage 225 less than its corresponding reference voltage, when this represents that just error increases, controller 212 just according to above-mentioned error to adjust its conducting working time (duty cycle) to inductive switch 221, make more conducting electric currents to output.
Above-mentioned only is a kind of embodiment for example, have in this area and to know that usually the knowledgeable should know with reference to present embodiment, if the light-emitting diode group with above-mentioned driving different colours is under the prerequisite, if a reference voltage only is provided, as long as change the design (for example changing the resistance value of feedback circuit) of feedback circuit 234 and 224, still can reach above-mentioned effect, not repeat them here.
In this LED drive 210 two circuit protection designs are arranged.The one, in order to respond the open fault that light-emitting diode group 222,232 may occur, this LED drive 210 needs the load over-voltage protection function, so LED drive 210 also includes mu balanced circuit 223 and 233; Another is to limit maximum output voltage 214 with controller 212.
Go on to say the foregoing circuit protection practice; when LED drive 210 provides each light-emitting diode group to have fixed current to make it luminous; controller 212 control of input voltage VI can being boosted can increase the current potential that boosts that arrival sets always and become output voltage 214.If this moment is unshielded mu balanced circuit 223 and 233, and output voltage 214 is too high may to cause damage to the element on the circuit.In addition, it is the both end voltage that controller 212 pins are surveyed feedback circuit 224 and 234 that protection LED drive 210 is avoided superpotential method, and CONTROLLER DESIGN 212 limits maximum output voltage 214.
Above-mentioned display device 200 is when being applied in when needing adjustment function backlight, reality with light-emitting diode group 222 dimming functions is an example as method, the controller 212 of LED drive 210 will provide full current to light-emitting diode group 222, reduce the current loading cycle and then reach light modulation, for example brightness to be reduced four minutes one, only need duty cycle of 75% that full current is provided.For example brightness to be reduced two minutes one, only need duty cycle of 50% that full current is provided.
Fig. 3 is the another kind of display device circuit diagram of the embodiment of the invention.This display device comprises backlight module 300.Backlight module 300 comprises LED drive 310, light-emitting diode group 222,232 and 342.LED drive 310 comprises inductance 311, main switch 213, switch 221,231 and 341, controller 312, mu balanced circuit 223,233 and 343 and feedback circuit 224,234 and 344.
Please refer to the LED drive 210 of Fig. 3 and comparison diagram 2, the controller 312 of LED drive 310 is driving circuits of amplification one light-emitting diode group 342, three of controller 312 controls independently loop comprise the VD loop of three switches 221,231 and 341 so three groups of light-emitting diode group 222,232 and 342 of controller 312 drivings.In the embodiment that drives three groups of light-emitting diode group 222,232,342, the color of using light-emitting diode group 222,232 and 342 in one preferred embodiment is respectively red, green and blue, and the display device that three colors like this are used in Fig. 3 can be used as colored backlight lamp source or other purposes.
Because light-emitting diode group 222,232 and 342 shared inductance 311, controller 312 control inductance 311 have three settings current potential that boosts.We are according to the maximum voltage of the required driving in three groups of light-emitting diode group, and more margin of safety scopes, select for use inductance 311 that rated output voltage 314 can be provided so that make input voltage VI have broad suitable opereating specification to boost and can obtain greater efficiency when driving, and maintain good insulation and Electrical Safety.
Above-mentioned display device 300 is the amplification of the driven for emitting lights diode group of Fig. 2 display device 200, so the control mode and the circuit protection method of the mode of driven for emitting lights diode group, each closed loop, is same as the embodiment explanation of Fig. 2, does not repeat them here.
If when wanting display device 300 to increase the number of driven for emitting lights diode group, usually know for the knowledgeable for having at correlative technology field of the present invention, circuit embodiments by the front, imitative above-mentioned steps increases the circuit of required driven for emitting lights diode group, and controller will be controlled each and independently comprise and the VD loop of all switches can implement the design of LED drive of the present invention in the path, closed loop.
Suppose redness, green and the blue light-emitting diode group 222,232 and 342 of Fig. 3, be identical with Fig. 1 redness, green and blue light-emitting diode group 113,123 and 133, the further use situation of comparison diagram 3 and the circuit component of the LED drive of Fig. 1.
At first, our comparison controller number.Tradition is wanted three controllers 117, and embodiments of the invention only need a controller 312.Controller 312 is concentrated the detecting in all switch controls and loop.
Secondly, we compare the inductance number.Tradition is wanted three inductance 111,121 and 131, and embodiments of the invention only need an inductance 311.
Then, we compare the main switch number.Tradition is wanted three main switches 116, and embodiments of the invention only need a main switch 213.
Therefore, when driven for emitting lights diode group number increases, imitative above-mentioned steps is analogized the LED drive design of embodiments of the invention, color when the multiple more light-emitting diode group of the required driving of LED drive, or be drive more when coming use when back lighting with light-emitting diode group, though required light-emitting diode group direct ratio increases, and will use a lot of LED drive compared to traditional approach, and the inventive method is only used one.LED drive takies circuit area and can significantly reduce, and circuit component uses can be more efficient.Because reduced the complexity of circuit-board laying-out, the flexibility ratio that makes LED drive be applied to electronic product improves.
The explanation of comprehensive the foregoing description as can be known, the advantage of LED drive of the present invention: can independently control two groups of light-emitting diode group, or more on demand situation increase and is controlled number.Can be used as the driving white backlight lamp source of display device or drive colored backlight lamp source.The planning control of can programming device comes driven for emitting lights diode group.Can have the load protection function.Can adjust the electric current of light-emitting diode group.Can switch main switch and each switch at a high speed.Can drive the light emitting diode series connection more than two.Can detect superpotential.The present invention also improves the disadvantage of traditional LED drive, many as the led driver circuit number of elements.
Though the present invention with preferred embodiment openly as above; right its is not that any those skilled in the art are under the situation that does not break away from the spirit and scope of the present invention in order to qualification the present invention; can change and modification, so protection scope of the present invention is as the criterion with the claim institute restricted portion that is proposed.
Claims (12)
1. LED drive, in order to drive one first group of light emitting diode and one second group of light emitting diode, this LED drive comprises:
One inductance, the one termination is received an input voltage;
One main switch, its first end couples the other end of this inductance, and its second end couples a common electric potential, in order to regulate the electric current of this inductance;
One first switch, its first end couple this first group of light emitting diode, and its second end couples the other end of this inductance;
One second switch, its first end couple this second group of light emitting diode, and its second end couples the other end of this inductance; And
One controller couples the control end of this main switch, this first switch and this second switch respectively, in order to controlling the conducting state of this main switch, this first switch and this second switch,
Wherein this LED drive also comprises:
One first feedback circuit, its first end couple this first group of light emitting diode and controller, and its second end couples this common electric potential; And
One second feedback circuit, its first end couple this second group of light emitting diode and controller, and its second end couples this common electric potential;
Wherein, this controller respectively according to the voltage of first end of this first feedback circuit and this second feedback circuit to control the ON time of this first switch and this second switch.
2. LED drive as claimed in claim 1, wherein this common electric potential is an earthing potential, and this main switch is a N transistor npn npn.
3. LED drive as claimed in claim 1 also comprises:
One first mu balanced circuit is coupled between first end and this common electric potential of this first switch; And
One second mu balanced circuit is coupled between first end and this common electric potential of this second switch.
4. LED drive as claimed in claim 1, wherein the color difference of this first group of light emitting diode and this second group of light emitting diode.
5. LED drive as claimed in claim 1, wherein this LED drive is also in order to driving one the 3rd group of light emitting diode, and this LED drive also comprises:
One the 3rd switch, its first end couple the 3rd group of light emitting diode, and its second end couples the other end of this inductance, and its control end couples this controller, and wherein this controller is also in order to control the conducting state of the 3rd switch.
6. LED drive as claimed in claim 5, wherein the color of this first group of light emitting diode, second group of light emitting diode and the 3rd group of light emitting diode is respectively red, green and blue.
7. display device comprises:
One backlight module comprises:
One first group of light emitting diode;
One second group of light emitting diode;
One inductance, the one termination is received an input voltage;
One main switch, its first end couples the other end of this inductance, and its second end couples a common electric potential, in order to regulate the electric current of this inductance;
One first switch, its first end couple this first group of light emitting diode, and its second end couples the other end of this inductance;
One second switch, its first end couple this second group of light emitting diode, and its second end couples the other end of this inductance; And
One controller couples the control end of this main switch, this first switch and this second switch respectively, in order to controlling the conducting state of this main switch, this first switch and this second switch,
Wherein this display device also comprises:
One first feedback circuit, its first end couple this first group of light emitting diode and controller, and its second end couples this common electric potential; And
One second feedback circuit, its first end couple this second group of light emitting diode and controller, and its second end couples this common electric potential.
Wherein, this controller respectively according to the voltage of first end of this first feedback circuit and this second feedback circuit to control the ON time of this first switch and this second switch.
8. display device as claimed in claim 7, wherein this common electric potential is an earthing potential, and this main switch is a N transistor npn npn.
9. display device as claimed in claim 7 also comprises:
One first mu balanced circuit is coupled between first end and this common electric potential of this first switch; And
One second mu balanced circuit is coupled between first end and this common electric potential of this second switch.
10. display device as claimed in claim 7, wherein the color difference of this first group of light emitting diode and this second group of light emitting diode.
11. display device as claimed in claim 7 also comprises:
One the 3rd group of light emitting diode; And
One the 3rd switch, its first end couple the 3rd group of light emitting diode, and its second end couples the other end of this inductance, and its control end couples this controller, and wherein this controller is also in order to control the conducting state of the 3rd switch.
12. display device as claimed in claim 11, wherein the color of this first group of light emitting diode, second group of light emitting diode and the 3rd group of light emitting diode is respectively red, green and blue.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101604042A CN100562911C (en) | 2006-11-15 | 2006-11-15 | LED drive and use its display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101604042A CN100562911C (en) | 2006-11-15 | 2006-11-15 | LED drive and use its display device |
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| Publication Number | Publication Date |
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| CN101188088A CN101188088A (en) | 2008-05-28 |
| CN100562911C true CN100562911C (en) | 2009-11-25 |
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| CNB2006101604042A Expired - Fee Related CN100562911C (en) | 2006-11-15 | 2006-11-15 | LED drive and use its display device |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102118903A (en) * | 2009-12-30 | 2011-07-06 | 富准精密工业(深圳)有限公司 | Drive circuit for LED (light-emitting diode) light fixture |
| CN105334937B (en) * | 2014-06-18 | 2018-12-14 | 联想(北京)有限公司 | A kind of electronic equipment and method of controlling switch |
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Granted publication date: 20091125 Termination date: 20161115 |