CN101388185B - Source driver and voltage drop detector thereof - Google Patents
Source driver and voltage drop detector thereof Download PDFInfo
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- CN101388185B CN101388185B CN2007101489759A CN200710148975A CN101388185B CN 101388185 B CN101388185 B CN 101388185B CN 2007101489759 A CN2007101489759 A CN 2007101489759A CN 200710148975 A CN200710148975 A CN 200710148975A CN 101388185 B CN101388185 B CN 101388185B
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- voltage
- comparer
- branch pressure
- power supply
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Abstract
The invention discloses a source cathode driver and a voltage drop detector thereof, wherein the source cathode driver is supplied power by a power supply device, the source cathode driver at least comprises a channel, at least an output pad, at least a switch and the voltage drop detector, the output pad is coupled with the channel, and the switch is connected between the output pad and presupposition voltage. The voltage drop detector is used to detect whether first supply voltage which is output from the power supply device is not enough, if not enough, a reset signal is produced, thereby conducting the switch.
Description
Technical field
The present invention relates to a kind of voltage drop detector that is used in the source electrode driver, and when particularly relating to a kind of voltage that is supplied to source electrode driver when power supply unit and reducing, can avoid on display, showing the source electrode driver of undesired image.
Background technology
In recent years, along with the progress of optics science and technology with semiconductor technology, liquid crystal indicator (LiquidCrystal Display; LCD) be widely used on the electronic product.Advantages such as LCD has that high image quality, volume are little, in light weight, low voltage drive and low consumpting power so be widely used in the products such as portable computer, personal digital assistant and colour television set, become the main flow of display.
Fig. 1 shows the synoptic diagram of the known source electrode driver 100 of the part that is used in LCD.Source electrode driver 100 comprises a plurality of passages at least.(data among the impact damper _ HV, impact damper _ LV) can input to a multiplexer (MUX) 102, via output pad (pad) (114,116), are sent to a display 104, to show corresponding image on display 104 again to be stored in impact damper in the passage.One transistor 106 is electrically connected between the output terminal of source electrode driver, with when needed, divides equally the voltage of output terminal.
Yet, when the power supply unit that supplies power to source electrode driver will be closed, the voltage that is supplied to source electrode driver can reduce, because voltage is not enough, impact damper just may maloperation, this can cause abnormal image, for example line defect (Line Defects) or striped (Band Mura) on display.
Summary of the invention
Therefore, the object of the present invention is to provide a kind of source electrode driver, have a voltage drop detector, can reduce the undesired image that is presented on the display in power supply unit conducting/when closing.
Another object of the present invention is to provide a kind of voltage drop detector, in order to detect whether positive conducting of power supply unit/close, if then produce one and reset signal (Reset Signal).
According to above-mentioned purpose of the present invention, a kind of source electrode driver is proposed, can power by a power supply unit.This source electrode driver comprises that at least at least one passage, at least one output pad couple this passage, at least one switch and a voltage drop detector.Above-mentioned switch is connected between an output pad and the predeterminated voltage.Whether voltage drop detector is not enough in order to detect from one first supply voltage of power supply unit output, if not enough, then produce one and resets signal, with the above-mentioned switch of conducting.
According to preferred embodiment of the present invention, whether voltage drop detector also can detect from one second supply voltage of power supply unit output not enough, if not enough, then produces the above-mentioned signal of reseting, with the above-mentioned switch of conducting.Above-mentioned source electrode driver also comprises an at least one multiplexer and a controller at least.Multiplexer is connected between passage and the output pad.Controller with according to the above-mentioned signal of reseting, disconnects channel and being connected that output is filled up in order to the control multiplexer.
Voltage drop detector comprises one first voltage divider and one first comparer at least.First voltage divider produces one first branch pressure voltage in order to according to the first supply voltage.Whether first comparer is in order to compare first branch pressure voltage and a critical voltage, not enough to differentiate the first supply voltage.Voltage drop detector also comprises one second voltage divider, one second comparer and one or door (OR Gate) at least.Second voltage divider produces one second branch pressure voltage in order to according to one second supply voltage from power supply unit output.Whether second comparer is in order to compare second branch pressure voltage and critical voltage, not enough to differentiate the second supply voltage.Or the door have two input ends, be connected to the output terminal of first comparer and second comparer respectively, reset signal with output.The first supply voltage is compared to the second supply voltage, and the first supply voltage is a high voltage, and first comparer is a high-voltage assembly, and second comparer is a low-voltage assembly.Voltage drop detector also comprises a level shifter at least, be connected in second comparer and or the door between.
According to another object of the present invention, a kind of voltage drop detector is proposed, be applicable in the one source pole driver whether voltage drop detector is not enough in order to detect from one first supply voltage of power supply unit output.A plurality of output pads of source electrode driver are connected to a predeterminated voltage via a switch.This voltage drop detector comprises one first voltage divider and one first comparer at least.First voltage divider produces one first branch pressure voltage in order to according to the first supply voltage.First comparer is in order to compare first branch pressure voltage and a critical voltage, if first branch pressure voltage less than critical voltage, is then exported one and reseted signal, with the above-mentioned switch of conducting.
According to preferred embodiment of the present invention, above-mentioned voltage drop detector also comprises one second voltage divider, one second comparer and one or door at least.Second voltage divider produces one second branch pressure voltage in order to according to one second supply voltage from power supply unit output.Second comparer is in order to compare second branch pressure voltage and critical voltage.Or the door have two input ends, be connected to the output terminal of first comparer and second comparer respectively, reset signal with output.Each comprises that at least a plurality of resistance connect first voltage divider and second voltage divider.Or door comprises that at least a rejection gate (NOR Gate) connects with a phase inverter.The first supply voltage is compared to the second supply voltage, and the first supply voltage is a high voltage, and first comparer is a high-voltage assembly, and second comparer is a low-voltage assembly.Voltage drop detector also comprises a level shifter at least, be connected in second comparer and or the door between.Whether voltage drop detector also can detect from one second supply voltage of power supply unit output not enough, if not enough, then produces the above-mentioned signal of reseting.
Description of drawings
For above and other objects of the present invention, feature, advantage and embodiment can be become apparent, being described in detail as follows of accompanying drawing:
Fig. 1 shows the synoptic diagram of the known source electrode driver of part that is used in LCD;
Fig. 2 shows the synoptic diagram according to the source electrode driver of preferred embodiment of the present invention;
Fig. 3 shows the part synoptic diagram according to another source electrode driver of preferred embodiment of the present invention;
Fig. 4 shows the synoptic diagram according to the voltage drop detector of preferred embodiment of the present invention.
The reference numeral explanation
100: source electrode driver 308: passage
102: multiplexer 310: passage
104: display 312: multiplexer
106: transistor 314: the output pad
114: output pad 316: the output pad
116: output pad 318: switch
200: source electrode driver 320: switch
202: power supply unit 322: switch
204: 402: the first voltage dividers of voltage drop detector
206: 404: the second voltage dividers of controller
208: 406: the first comparers of passage
210: 408: the second comparers of passage
212: 410: the first phase inverters of multiplexer
214: 412: the second phase inverters of output pad
216: 414: the three phase inverters of output pad
218: 416: the four phase inverters of switch
220: switch 418: level shifter
300: 420: the five phase inverters of source electrode driver
302: power supply unit 422: rejection gate
304: 424: the hex inverters of voltage drop detector
306: controller 426: or door
Embodiment
In order to make narration of the present invention more detailed and complete, can be with reference to following description and in conjunction with the diagram of Fig. 2 to Fig. 4.
Please refer to Fig. 2, Fig. 2 shows the synoptic diagram according to the source electrode driver of preferred embodiment of the present invention.Source electrode driver 200 among Fig. 2 is by a power supply unit 202 power supply, and source electrode driver comprises at least that at least one channel (channel 208, channel 210...), at least one output pad (output pad 214, output pad 216...) couple that this passage, at least one multiplexer (MUX) 212 are connected between passage and the output pad, at least one switch (switch 218, switch 220...) is connected between an output pad and the predeterminated voltage, a voltage drop detector 204 and power supply unit 202 joins and a controller 206 is connected to voltage drop detector 204.Power supply unit 202 can provide the one first supply voltage and the low level one second supply voltage of high level.
Whether positive voltage drop detector 204 can be differentiated power supply conducting or close, if then produce one and reset signal RS.The judgement of power turn-on/close is by detecting one of them deficiency whether from the first supply voltage of power supply unit 202 outputs and the second supply voltage, that is, whether be lower than some critical value.Reseting signal RS can actuating switch (switch 218, switch 220...), therefore, output pad (214,216...) can the output predeterminated voltage to display (not being illustrated among the figure).In preferred embodiment of the present invention, predeterminated voltage is made as a common magnitude of voltage, so in power supply unit conducting/when closing, display can show corresponding a black image or a white image.
Reset signal RS and can deliver to controller 206 again.Controller 206 is then according to reseting signal RS, produce a control signal CN, and this control signal CN is sent to multiplexer, to disconnect passage and being connected that output is filled up, therefore, when the power supply unit 202 that supplies power to source electrode driver is about to conductings/when closing, impact damper that may maloperation in the passage just can not transmit undesired data to the output pad.
Please refer to Fig. 3, Fig. 3 shows the part synoptic diagram according to another source electrode driver of preferred embodiment of the present invention.Source electrode driver 300 among Fig. 3 is by a power supply unit 302 power supplies, and source electrode driver comprises channel 308 at least and channel 310, multiplexer (MUX) 312, output pad 314 is with output pad 316, switch 318, switch 320 and switch 322, a voltage drop detector 304 joins with power supply unit 302 and a controller 306 is connected to voltage drop detector 304.Output pad 314 is coupled to channel 308 and channel 310 with output pad 316 via multiplexer 312.Switch 322 is electrically connected between the output pad 314 and output pad 316 of source electrode driver, with when needed, divides equally the voltage of output terminal.Switch 318 respectively is connected between corresponding the output pad and a predeterminated voltage with switch 320, and in this example, this predeterminated voltage is voltage VSSA, and switch 318 is controlled by reseting signal RS with switch 320.
When power supply unit 302 normal power supplies during to source electrode driver 300, the data in the channel can input to multiplexer 312, via output pad 314 and output pad 316, are sent to a display (not being illustrated among the figure), to show corresponding image on display again.And when power supply unit 302 was about to conducting or closes, the voltage that is sent to source electrode driver 300 began deficiency.If the undertension of power supply unit 302 outputs, then voltage drop detector 304 can produce one and reset signal RS, and this is reseted signal RS deliver to switch 318 and switch 320, with actuating switch 318 and switch 320.Therefore, predeterminated voltage, for example voltage VSSA just can be sent to output pad 314 and output pad 316, delivers to display again, to show corresponding a black image or a white image.
In addition, controller 306 can produce a control signal CN, and this control signal CN is sent to multiplexer 312 according to reseting signal RS, so that multiplexer 312 is remained on high impedance, to disconnect channel 308, channel 310 and to export being connected of pad 314, output pad 316.This can be avoided when switch 318 during with switch 320 conductings, the big electric current that causes because of the impact damper maloperation in the passage flow through switch 318 and switch 320.Switch 322 controls its conducting by control signal CN or cuts out.
Below will describe the structure of voltage drop detector and the generation of reseting signal RS in detail.
Please refer to Fig. 4, Fig. 4 shows the synoptic diagram according to the voltage drop detector of preferred embodiment of the present invention.Voltage drop detector 304 among Fig. 4 comprises one first voltage divider 402, one second voltage divider 404, one first comparer 406, one second comparer 408, one first phase inverter 410, one second phase inverter 412, one the 3rd phase inverter 414, one the 4th phase inverter 416, a level shifter 418, one the 5th phase inverter 420 and one or door 426 at least.Or door 426 comprises that at least a rejection gate 422 connects with a hex inverter 424.First voltage divider 402 comprises the resistance R 1 of series connection to R7, and second voltage divider 404 comprises that the resistance R 11 of series connection is to R16.
Similarly, second comparer 4 08 is the second branch pressure voltage VD1 and critical voltage VTH relatively, and produces one second comparison signal RSD.If the second branch pressure voltage VD1 is less than critical voltage VTH, then the second comparison signal RSD is a high level, and the expression power supply unit is about to conducting/close.If the second branch pressure voltage VD1 is greater than critical voltage VTH, then the second comparison signal RSD is a low level, and expression power supply unit normal power supply is to source electrode driver.The first supply voltage VDDA is compared to the second supply voltage VDDD, and the first supply voltage VDDA is a high voltage, and first comparer is a high-voltage assembly, and second comparer is a low-voltage assembly.The setting of the first branch pressure voltage VA1, the second branch pressure voltage VD1 and critical voltage VTH all can be determined by the user.
Critical voltage VTH is produced by the circuit that can not be subjected to power supply unit output voltage reduction influence easily, for example can be band gap voltage generator (Band-gap Voltage Generator).
The first comparison signal RSA can be via first phase inverter 410 and second phase inverter 412, is sent to or an input end of door 426.The second comparison signal RSD can be sent to level shifter 418, with the level of the second comparison signal RSD that is shifted via the 3rd phase inverter 414 and the 4th phase inverter 416.The second comparison signal RSD that level has been shifted can be again via the 5th phase inverter 420, is sent to or another input end of door 426.If the first comparison signal RSA and the second comparison signal RSD be low level, then or door 426 export a low level signal, represent that the power supply unit normal power supply to source electrode driver, therefore, resets signal and can not produce.On the contrary, if the first comparison signal RSA and/or the second comparison signal RSD are high level, then or door 426 outputs one high level signal, the expression power supply unit is about to conducting/close, and resets signal RS and just can produce.Then, reset signal RS can actuating switch 318 with switch 320, therefore, output pad 314 just can be connected to predeterminated voltage with output pad 316.
By the invention described above preferred embodiment as can be known, an advantage of the present invention is exactly, and the present invention can be in power supply unit conducting/when closing, reduce the undesired image that is presented on the display.
By the invention described above preferred embodiment as can be known, another advantage of the present invention is exactly, and the present invention uses voltage drop detector, can detect whether positive conducting of power supply unit/close, if then produce and reset signal.
Though the present invention discloses as above with a preferred embodiment; right its is not in order to qualification the present invention, those skilled in the art, under the premise without departing from the spirit and scope of the present invention; can do some changes and modification, so protection scope of the present invention should be as the criterion with claim of the present invention.
Claims (9)
1. a source electrode driver can be powered by a power supply unit, and this source electrode driver comprises at least:
At least one passage;
At least one output pad couples this passage;
At least one switch is connected between this an output pad and the predeterminated voltage;
One voltage drop detector, it comprises:
One first voltage divider in order to according to one first supply voltage from this power supply unit output, produces one first branch pressure voltage;
One first comparer, whether not enough in order to relatively this first branch pressure voltage and a critical voltage to differentiate this first supply voltage, if this first branch pressure voltage less than this critical voltage, then produces one and resets signal, with this switch of conducting;
One second voltage divider in order to according to one second supply voltage from this power supply unit output, produces one second branch pressure voltage;
One second comparer, whether not enough in order to relatively this second branch pressure voltage and this critical voltage to differentiate this second supply voltage, if this second branch pressure voltage less than this critical voltage, then produces this and resets signal, with this switch of conducting; And
One or the door, have the output terminal that two input ends are connected to this first comparer and this second comparer respectively, reset signal to export this.
2. source electrode driver as claimed in claim 1 also comprises at least:
At least one multiplexer is connected between this passage and this output pad; And
One controller in order to control this multiplexer, to reset signal according to this, disconnects being connected of this passage and this output pad.
3. source electrode driver as claimed in claim 1, wherein this first supply voltage is compared to this second supply voltage, and this first supply voltage is a high voltage, and this first comparer is a high-voltage assembly, and this second comparer is a low-voltage assembly.
4. source electrode driver as claimed in claim 3, wherein this voltage drop detector also comprises a level shifter at least, be connected in this second comparer and should or the door between.
5. a voltage drop detector is applicable in the one source pole driver, and this source electrode driver can be by power supply unit power supply, and a plurality of output pads of this source electrode driver are connected to a predeterminated voltage via a switch, and this voltage drop detector comprises at least:
One first voltage divider in order to according to one first supply voltage from this power supply unit output, produces one first branch pressure voltage;
One first comparer, whether not enough in order to relatively this first branch pressure voltage and a critical voltage to differentiate this first supply voltage, if this first branch pressure voltage less than this critical voltage, is then exported one and is reseted signal, with this switch of conducting;
One second voltage divider in order to according to one second supply voltage from this power supply unit output, produces one second branch pressure voltage;
One second comparer, whether not enough in order to relatively this second branch pressure voltage and this critical voltage to differentiate this second supply voltage, if this second branch pressure voltage less than this critical voltage, is then exported this and is reseted signal, with this switch of conducting; And
One or the door, have the output terminal that two input ends are connected to this first comparer and this second comparer respectively, reset signal to export this.
6. voltage drop detector as claimed in claim 5, wherein this first voltage divider and this second voltage divider respectively comprise a plurality of resistance of connecting at least.
7. voltage drop detector as claimed in claim 5 wherein is somebody's turn to do or door comprises a rejection gate and a phase inverter that is connected in series at least.
8. voltage drop detector as claimed in claim 5, wherein this first supply voltage is compared to this second supply voltage, and this first supply voltage is a high voltage, and this first comparer is a high-voltage assembly, and this second comparer is a low-voltage assembly.
9. voltage drop detector as claimed in claim 8 also comprises a level shifter at least, be connected in this second comparer and should or the door between.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101489759A CN101388185B (en) | 2007-09-12 | 2007-09-12 | Source driver and voltage drop detector thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2007101489759A CN101388185B (en) | 2007-09-12 | 2007-09-12 | Source driver and voltage drop detector thereof |
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| CN101388185A CN101388185A (en) | 2009-03-18 |
| CN101388185B true CN101388185B (en) | 2011-12-28 |
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| CN2007101489759A Active CN101388185B (en) | 2007-09-12 | 2007-09-12 | Source driver and voltage drop detector thereof |
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| CN114299872B (en) * | 2022-01-04 | 2023-07-18 | 京东方科技集团股份有限公司 | Driving circuit, driving method thereof and display device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5745092A (en) * | 1993-12-22 | 1998-04-28 | Seiko Epson Corporation | Liquid-Crystal display system and power supply method that supply different logic source voltages to signal and scan drivers |
| CN1956334A (en) * | 2005-10-27 | 2007-05-02 | 三洋电机株式会社 | Low voltage detection circuit |
| CN1959482A (en) * | 2006-10-25 | 2007-05-09 | 友达光电股份有限公司 | Liquid crystal display capable of eliminating ghost, and method |
-
2007
- 2007-09-12 CN CN2007101489759A patent/CN101388185B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5745092A (en) * | 1993-12-22 | 1998-04-28 | Seiko Epson Corporation | Liquid-Crystal display system and power supply method that supply different logic source voltages to signal and scan drivers |
| CN1956334A (en) * | 2005-10-27 | 2007-05-02 | 三洋电机株式会社 | Low voltage detection circuit |
| CN1959482A (en) * | 2006-10-25 | 2007-05-09 | 友达光电股份有限公司 | Liquid crystal display capable of eliminating ghost, and method |
Non-Patent Citations (1)
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| 同上. |
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