CN104123901A - LED (Light-Emitting Diode) backlight working condition detection circuit - Google Patents
LED (Light-Emitting Diode) backlight working condition detection circuit Download PDFInfo
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- CN104123901A CN104123901A CN201410400429.XA CN201410400429A CN104123901A CN 104123901 A CN104123901 A CN 104123901A CN 201410400429 A CN201410400429 A CN 201410400429A CN 104123901 A CN104123901 A CN 104123901A
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Abstract
The invention relates to an LED (Light-Emitting Diode) backlight working condition detection circuit, and belongs to the technical field of LED. The circuit comprises a comparison amplifying circuit and a monitoring circuit, wherein input signals of the comparison amplifying circuit are monitoring signals; the comparison amplifying circuit is connected and output to the monitoring circuit; the comparison amplifying circuit comprises a comparator; the negative end input of the comparator is reference voltage, and the positive end input of the comparator is monitoring signals; the comparator is used for converting the monitoring signals into signals with invariable signal waveform, wherein the amplitude of the signals is between 0 and +3.3V. Through information returned by a plurality of monitoring sites, the positions and types of faults can be concluded, so that the fault predication time can be greatly reduced, the fault locations are understood in advance, and the problem that an LED backlight maintenance circuit is complicated, high in cost and troublesome to disassemble in the prior art is solved.
Description
Technical field
The invention belongs to LED technical field, be specifically related to a kind of LED-backlit Working state checking circuit.
Background technology
More and more electronic products have been equipped with LCD display, such as TV, mobile phone, digital camera etc.Because LCD display self is not luminous, in order clearly to see the content showing on screen, need backlight to provide backlight.The general LED that adopts is as the backlight of display screen, and LED-backlit source is comprised of several LED.In order to meet the requirement of backlight drive circuit to brightness, work efficiency and brightness regulation comfort level.Adopt the mode of constant current reliably to drive LED, by selecting the resistance of suitable resistance to carry out the electric current of setup control LED brightness, utilize the PWM of low frequency variable duty ratio to carry out linearity light adjusting simultaneously.
Because electron device has certain serviceable life, after using the regular hour or because misoperation causes device electrostatic damage, cause LED-backlit cisco unity malfunction.General display device LED-backlit plate and backlight drive board all, at the front end of equipment, will unload bonnet and peripheral PCB and structural member once break down, and bring great difficulty and inconvenience to maintenance and troubleshooting.In order to reduce fault location time and to simplify troubleshooting process, need to LED with and driving circuit carry out real-time monitoring.
Summary of the invention
In order to overcome, in prior art, LED-backlit maintenance circuit is complicated, cost is high, the problem of dismounting trouble, the invention provides a kind of LED-backlit Working state checking circuit.
Technical scheme of the present invention is: a kind of LED-backlit Working state checking circuit, and this circuit comprises comparison amplifying circuit and supervisory circuit, and relatively the input signal of amplifying circuit is monitor signal, and relatively amplifying circuit connection outputs to supervisory circuit.
Described relatively amplifying circuit comprises comparer, and the negative terminal of comparer is input as reference voltage, anode is input as monitor signal, and comparer is converted into amplitude constant signal of signal waveform between 0～+ 3.3V by monitor signal.
That described comparer is selected is LM2903M, and comparer connects the power supply using and is+5V power supply.
Described relatively amplifying circuit also comprises 6 resistance (R1, R2, R3, R4, R5, R6), capacitor C 1 and capacitor C 2, No. 4 pin ground connection of comparer, No. 8 pin connects power supply and is connected with one end of resistance 5, one end of one end of No. 5 pins and capacitor C 2 and resistance R 2, resistance R 4 is connected, one end of one end of No. 5 pins and capacitor C 1 and resistance R 1, resistance R 3 is connected, and No. 7 pin and one end of resistance R 5, one end of resistance R 6 is connected.Described supervisory circuit adopts chip ADM706RAR.Described supervisory circuit also comprises capacitor C 3, capacitor C 4, resistance R 7 and resistance R 8,1,2, No. 4 pin of chip ADM706RAR is connected to one end of power supply, capacitor C 3 and capacitor C 4 simultaneously, No. 3 pin ground connection of chip, 5, No. 7 pins are unsettled, No. 6 pin is connected with one end of resistance R 7, and No. 8 pin is connected with one end of resistance R 8; No. 8 pins are output signal ports simultaneously.The power supply using in described supervisory circuit is+3.3V power supply.
The present invention has following good effect: the LED-backlit Working state checking circuit that the present invention proposes, and the information of have 1, returning to by each control point, can infer abort situation and type; 2, can greatly reduce the fault judgement time, understand in advance trouble location, facilitate troubleshooting; 3, circuit is realized simply, and pure hardware circuit forms, and does not use controller, realizes the advantages such as with low cost.
Accompanying drawing explanation
Fig. 1 is the control point schematic diagram of the specific embodiment of the invention;
Fig. 2 is the supervisory circuit figure of the specific embodiment of the invention;
Fig. 3 is the working waveform figure of the ADM706RAR chip of the specific embodiment of the invention.
Embodiment
Contrast accompanying drawing below, by the description to embodiment, the specific embodiment of the present invention is as the effect of the mutual alignment between the shape of each related member, structure, each several part and annexation, each several part and principle of work, manufacturing process and operation using method etc., be described in further detail, to help those skilled in the art to have more complete, accurate and deep understanding to inventive concept of the present invention, technical scheme.
The present invention proposes a kind of LED-backlit Working state checking circuit, and by driving circuit difference is monitored simultaneously, after circuit goes wrong, the information of returning according to each control point, can infer it is the fault of certain device or certain circuit.Can greatly reduce like this fault judgement time, roughly understand after trouble location, equipment is carried out to detachable maintaining, facilitate troubleshooting.Circuit is realized simply simultaneously, and error detection rate is high, hardware circuit, consists of completely, does not use any controller, realizes with low cost.
Backlight circuit most common failure has: it is abnormal etc. that PWM ripple is not worked, inputted to LED open circuit and short circuit, metal-oxide-semiconductor short circuit and open circuit, comparer.For a string LED, it is 0V that LED open circuit and metal-oxide-semiconductor open circuit make to adjust pipe source voltage, and grid control signal is normal; LED short circuit meeting makes to adjust the drain electrode of pipe and the pressure reduction of source electrode increases, and grid control signal is normal; When comparer work is undesired, adjusting pipe source voltage is 0V, and grid control signal is 0V.If so the pwm signal of monitoring input, the output signal of comparer, adjust pipe source signal, so in the time of fault, by judging that the signal of these three monitoring points just can obtain type and the position of fault.
As shown in Figure 1, monitor signal (pwm signal) and setting working current signal be the input signal of amplifying circuit as a comparison, and relatively the output of amplifying circuit is connected to and adjusts pipe (being observation circuit).The pwm signal (being monitor signal) of definition input, the output signal of comparer, adjust pipe these three control points of source signal be respectively S1, S2, S3.Indication circuit is working properly during S1S2S3=111; If S1S2S3=000, if now the voltage of monitoring is all normal, illustrates that PWM input is abnormal; If S1S2S3=100, comparer operation irregularity; If S1S2S3=110, metal-oxide-semiconductor operation irregularity.
By above analysis, the S1 to Fig. 1, S2, S3 point is monitored.Due to S1, S2, the characteristics of signals that S3 is ordered is different: S1 point is the LVTTL signal of 3.3V, if the whether cyclical variation of its waveform of monitoring, and S2, although S3 point is also the waveform changing in the cycle, but signal amplitude is larger, need to first carry out amplifier operation, its amplitude is adjusted between 0～+ 3.3V, monitor its wave form varies, testing circuit as shown in Figure 2 again.
As shown in Figure 2, a kind of LED-backlit Working state checking circuit, this circuit comprises comparison amplifying circuit and supervisory circuit, and relatively the input signal of amplifying circuit is monitor signal, and relatively amplifying circuit connection outputs to supervisory circuit.
Relatively amplifying circuit comprises comparer, a plurality of resistance and a plurality of electric capacity, comparer is LM2903M, the negative terminal of comparer is input as reference voltage, anode is input as monitor signal, and comparer is converted into amplitude constant signal of signal waveform between 0～+ 3.3V by monitor signal.No. 4 pin ground connection of comparer LM2903M, No. 8 pin meets power supply+5V and is connected with one end of resistance R 5, one end of one end of No. 5 pins and capacitor C 2 and resistance R 2, resistance R 4 is connected, one end of one end of No. 5 pins and capacitor C 1 and resistance R 1, R3 is connected, and No. 7 pin and one end of resistance R 5, one end of resistance R 6 is connected.
Supervisory circuit adopts chip ADM706RAR, 1,2, No. 4 pin of chip ADM706RAR is connected to one end of power supply, capacitor C 3 and capacitor C 4 simultaneously, No. 3 pin ground connection of chip, and 5, No. 7 pin is unsettled, No. 6 pin is connected with one end of resistance R 7, and No. 8 pin is connected with one end of resistance R 8; No. 8 pin is output signal port simultaneously, and the power supply using in supervisory circuit is+3.3V power supply.
In testing circuit, be connected with a plurality of resistance and electric capacity, one end of resistance R 1 is connected with signal VREF (reference voltage), and one end is connected with No. 6 pins of resistance R 3, capacitor C 1 one end and comparer chip LM2903M.One end ground connection of resistance R 3, the other end and resistance R 1, No. 6 pins of capacitor C 1 one end and chip LM2903M connect.Capacitor C 1 one end ground connection, No. 6 pins of the other end and resistance R 1, R3 and chip LM2903M are connected.One end of resistance R 2 is connected with signal SIGNAL_INPUT, and No. 5 pins of the other end and resistance R 4, capacitor C 2 one end and U1 are connected.One end ground connection of resistance R 4, No. 5 pins of the other end and resistance R 2, capacitor C 2 one end and chip LM2903M are connected.One end ground connection of capacitor C 2, No. 5 pins of the other end and resistance R 2, resistance R 4 one end and chip LM2903M are connected.No. 8 pins of one end of resistance R 5 and power supply+5V, chip ADM706RAR are connected, and the other end is connected with resistance R 6; One end of resistance R 6 is connected with resistance R 5, and the other end is connected with resistance R 7; One end ground connection of resistance R 7, No. 6 pins of the other end and resistance R 6, chip ADM706RAR are connected; One end of resistance R 8 is connected with+3.3V power supply, and No. 8 pins of the other end and chip ADM706RAR are connected, and signal DETECET_OUT is as input No. 8 pins of access chip ADM706RAR simultaneously; One end ground connection of capacitor C 3,1,2, No. 4 pin of the other end and chip ADM706RAR is connected, and receive+3.3V power supply; One end ground connection of capacitor C 4, the other end is connected with capacitor C 3, and receive+3.3V power supply.
During use, the output signal of comparer, adjustment pipe source signal are nursed one's health between 0～+ 3.3V by comparer, if VREF in Fig. 2 is a fixed value, the negative terminal that is comparer LM2903M by electric resistance partial pressure provides reference voltage; The signal of input signal SIGNAL_INPUT for monitoring, is passed through electric resistance partial pressure, the anode of input comparator LM2903M.Adjust suitable negative terminal voltage, making SIGNAL_INPUT be converted into amplitude is 0～+ 3.3V, the signal that original signal waveform is constant.Signal after conversion, as the input of the WDI end of watchdog chip ADM706RAR, does not change when edge occurs input signal after Twd>1.6S, WDO (No. 8) number pin output low level, and the oscillogram of work is as shown in Figure 3.During due to LED drive circuit, by pwm signal, control brightness, the signal waveform cycle of selected control point is the same period of wave with PWM, and the light modulation cycle of PWM ripple is also less than 1.6S from far away.So the output state of each monitoring point is all high level when LED light adjusting circuit is working properly, output low level just in the time of fault only.By the duty output of three kinds of signals selecting, fault type when can judge the duty of backlight circuit and breaking down according to the logical combination of three kinds of signals, reduces the fault judgement time enough greatly, has understood in advance trouble location, facilitates troubleshooting.
By reference to the accompanying drawings the present invention is exemplarily described above; obviously specific implementation of the present invention is not subject to the restrictions described above; as long as adopted the improvement of the various unsubstantialities that method of the present invention design and technical scheme carry out; or without improving, design of the present invention and technical scheme are directly applied to other occasion, all within protection scope of the present invention.
Claims (7)
1. a LED-backlit Working state checking circuit, is characterized in that, this circuit comprises comparison amplifying circuit and supervisory circuit, and relatively the input signal of amplifying circuit is monitor signal, and relatively amplifying circuit connection outputs to supervisory circuit.
2. LED-backlit Working state checking circuit according to claim 1, it is characterized in that, described relatively amplifying circuit comprises comparer, the negative terminal of comparer is input as reference voltage, anode is input as monitor signal, and comparer is converted into amplitude constant signal of signal waveform between 0～+ 3.3V by monitor signal.
3. LED-backlit Working state checking circuit according to claim 2, is characterized in that, that described comparer is selected is LM2903M, and comparer connects the power supply using and is+5V power supply.
4. LED-backlit Working state checking circuit according to claim 2, it is characterized in that, described relatively amplifying circuit also comprises 6 resistance (R1, R2, R3, R4, R5, R6), capacitor C 1 and capacitor C 2, No. 4 pin ground connection of comparer, No. 8 pin connects power supply and is connected with one end of resistance 5, one end of one end of No. 5 pins and capacitor C 2 and resistance R 2, resistance R 4 is connected, one end of one end of No. 5 pins and capacitor C 1 and resistance R 1, resistance R 3 is connected, and No. 7 pin and one end of resistance R 5, one end of resistance R 6 is connected.
5. LED-backlit Working state checking circuit according to claim 1, is characterized in that, described supervisory circuit adopts chip ADM706RAR.
6. LED-backlit Working state checking circuit according to claim 5, it is characterized in that, described supervisory circuit also comprises capacitor C 3, capacitor C 4, resistance R 7 and resistance R 8,1,2, No. 4 pin of chip ADM706RAR is connected to one end of power supply, capacitor C 3 and capacitor C 4 simultaneously, No. 3 pin ground connection of chip, 5, No. 7 pins are unsettled, and No. 6 pin is connected with one end of resistance R 7, and No. 8 pin is connected with one end of resistance R 8; No. 8 pins are output signal ports simultaneously.
7. LED-backlit Working state checking circuit according to claim 5, is characterized in that, the power supply using in described supervisory circuit is+3.3V power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410400429.XA CN104123901A (en) | 2014-08-14 | 2014-08-14 | LED (Light-Emitting Diode) backlight working condition detection circuit |
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| CN201410400429.XA CN104123901A (en) | 2014-08-14 | 2014-08-14 | LED (Light-Emitting Diode) backlight working condition detection circuit |
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| CN104123901A true CN104123901A (en) | 2014-10-29 |
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| CN201410400429.XA Pending CN104123901A (en) | 2014-08-14 | 2014-08-14 | LED (Light-Emitting Diode) backlight working condition detection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108983453A (en) * | 2018-07-26 | 2018-12-11 | 武汉天马微电子有限公司 | Backlight module detection device, detection jig and display module |
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| JP2001272938A (en) * | 2000-03-28 | 2001-10-05 | Sharp Corp | Color tone adjusting circuit and back light module and light emitting diode display device provided with the same circuit |
| CN101707837A (en) * | 2009-11-27 | 2010-05-12 | 上海晶丰明源半导体有限公司 | LED drive circuit of source driver with change of output voltage and induction quantity keeping constant current |
| CN102254526A (en) * | 2010-05-19 | 2011-11-23 | 索尼公司 | Light-emitting element driving device and display device |
| CN103325345A (en) * | 2012-03-23 | 2013-09-25 | 索尼公司 | Light emitting element drive device, light emitting element drive method, and display apparatus |
| CN103617782A (en) * | 2013-12-04 | 2014-03-05 | 中航华东光电有限公司 | LED backlight redundant backup circuit and control method thereof |
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2014
- 2014-08-14 CN CN201410400429.XA patent/CN104123901A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001272938A (en) * | 2000-03-28 | 2001-10-05 | Sharp Corp | Color tone adjusting circuit and back light module and light emitting diode display device provided with the same circuit |
| CN101707837A (en) * | 2009-11-27 | 2010-05-12 | 上海晶丰明源半导体有限公司 | LED drive circuit of source driver with change of output voltage and induction quantity keeping constant current |
| CN102254526A (en) * | 2010-05-19 | 2011-11-23 | 索尼公司 | Light-emitting element driving device and display device |
| CN103325345A (en) * | 2012-03-23 | 2013-09-25 | 索尼公司 | Light emitting element drive device, light emitting element drive method, and display apparatus |
| CN103617782A (en) * | 2013-12-04 | 2014-03-05 | 中航华东光电有限公司 | LED backlight redundant backup circuit and control method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108983453A (en) * | 2018-07-26 | 2018-12-11 | 武汉天马微电子有限公司 | Backlight module detection device, detection jig and display module |
| CN108983453B (en) * | 2018-07-26 | 2021-11-05 | 武汉天马微电子有限公司 | Backlight module detection device, detection jig and display module |
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Application publication date: 20141029 |
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