CN101388188B - Source driver and noise suppression method thereof - Google Patents
Source driver and noise suppression method thereof Download PDFInfo
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- CN101388188B CN101388188B CN 200710154232 CN200710154232A CN101388188B CN 101388188 B CN101388188 B CN 101388188B CN 200710154232 CN200710154232 CN 200710154232 CN 200710154232 A CN200710154232 A CN 200710154232A CN 101388188 B CN101388188 B CN 101388188B
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- 238000000034 method Methods 0.000 title claims abstract description 18
- 230000001629 suppression Effects 0.000 title abstract 2
- 238000010586 diagram Methods 0.000 description 8
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000007812 deficiency Effects 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- NHDHVHZZCFYRSB-UHFFFAOYSA-N pyriproxyfen Chemical compound C=1C=CC=NC=1OC(C)COC(C=C1)=CC=C1OC1=CC=CC=C1 NHDHVHZZCFYRSB-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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Abstract
The invention discloses a source driver and a noise suppression method thereof, which can suppress the noise output by the source driver when a power supply is switched on/off. The source driver at least comprises a multiplexer, at least two channels and at least two output ports. The channels are coupled to the output ports via multiplexers. The source driver can be powered by a first supply voltage output by the power supply. The output ports are connected by a voltage sharing switch. The method at least comprises the following steps. First, it is determined whether the first supply voltage is insufficient, and if not, the following steps are performed. The switch is equally divided by the cut-off voltage, and then the multiplexer disconnects the channel from the output port.
Description
Technical field
The present invention relates to a kind of source electrode driver and noise suppressing method thereof, and particularly relate to a kind of source electrode driver and noise suppressing method thereof, can when the power supply unit conduction and cut-off, suppress the noise of source electrode driver output.
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 existing source electrode driver 100 that is used in LCD.Source electrode driver 100 comprises at least two passages (108,110), a multiplexer (MUX) 112, at least two output ports (114,116), a data bus 118 and the equal switch-dividing of a voltage (Charge SharingSwitch) 120 at least.Path 10 8 and 110 is connected to output port 114 and 116 respectively via multiplexer 112.The equal switch-dividing 120 of voltage is electrically connected between output port 114 and 116, with when needed, divides equally the voltage of output terminal.Each channel has a shift register (122 or 132), a latch units (Latch Unit) (123 or 133), a level shifter (128 or 138) and a digital/analog converter (DAC) (130 or 140).Each latch units comprises that at least one first latchs (124 or 134) and one second and latchs (126 or 136) and connect.Data transmission and is stored in the latch units on data bus 118, what is more, data are stored in first earlier and latch, and is stored in second again and latchs.Data can be sent to a display (not shown) again via output port 114 and 116, to show corresponding image on display.
Yet, when the power supply unit that supplies power to source electrode driver will end, the voltage that is supplied to source electrode driver can reduce, because voltage is not enough, channel just may misoperation, this can cause abnormal image, for example line defect (Line Defects) or striped (Band Mura) on display.
Summary of the invention
Therefore, purpose of the present invention is providing a kind of source electrode driver and noise suppressing method thereof exactly, can reduce the undesired image that is presented on the display when the power supply unit conduction and cut-off.
Whether just another object of the present invention is providing a kind of source electrode driver exactly, has a voltage drop detector, in order to detect power supply unit conduction and cut-off, if yes, then produce a reset signal (Reset Signal).
According to above-mentioned purpose of the present invention, propose a kind ofly when a power supply unit conduction and cut-off, suppress the method for the noise of one source pole driver output.This source electrode driver comprises a multiplexer, at least two passages and at least two output ports at least.Passage couples output port via multiplexer.Source electrode driver can further can be supplied power voltage supply by one second of this power supply unit output by one first supply power voltage supply of power supply unit output.The equal switch-dividing of voltage is connected between described two output ports at least.Above-mentioned method comprises the following steps at least.Produce one first branch pressure voltage according to this first supply voltage, relatively whether this first branch pressure voltage and a critical voltage be not enough to differentiate this first supply voltage, if this first branch pressure voltage less than this critical voltage, then produces a reset signal; Produce one second branch pressure voltage according to this second supply voltage, relatively whether this second branch pressure voltage and this critical voltage be not enough to differentiate this second supply voltage, if this second branch pressure voltage less than this critical voltage, then produces this reset signal.Carry out the following step after producing this reset signal: the equal switch-dividing of cut-off voltage, then, multiplexer disconnection passage is connected with output port.
According to another object of the present invention, a kind of source electrode driver is proposed, can power by a power supply unit.This source electrode driver comprises at least two passages, a multiplexer, at least two output ports, the equal switch-dividing of a voltage and a voltage drop detector at least.Output port couples passage via multiplexer.The equal switch-dividing of voltage is connected between the output port.Whether voltage drop detector is not enough in order to detect by one first supply voltage of power supply unit output, if it is not enough, then produce a reset signal, whether not enoughly further can detect from one second supply voltage of this power supply unit output, if it is not enough, then produce this reset signal,, and disconnect being connected of passage and output port by multiplexer with the equal switch-dividing of cut-off voltage.This voltage drop detector comprises at least: first voltage divider in order to according to this first supply voltage, produces one first branch pressure voltage; And first comparer, in order to relatively this first branch pressure voltage and a critical voltage, whether not enough to differentiate this first supply voltage; Second voltage divider in order to according to one second supply voltage from this power supply unit output, produces one second branch pressure voltage; Whether second comparer is in order to relatively this second branch pressure voltage and this critical voltage, not enough to differentiate this second supply voltage; And or the door, have the output terminal that two input ends are connected to this first comparer and this second comparer respectively, to export this reset signal.
Description of drawings
For above and other objects of the present invention, feature, advantage and embodiment can be become apparent, shown in being described in detail as follows of accompanying drawing:
Fig. 1 shows the synoptic diagram of the existing source electrode driver 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 synoptic diagram according to another source electrode driver of preferred embodiment of the present invention; And
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 306: controller
108: passage 308: passage
110: passage 310: passage
112: multiplexer 312: multiplexer
114: output port 314: output port
116: output port 316: output port
118: data bus 318: data bus
120: the equal switch-dividing 320 of voltage: the equal switch-dividing of voltage
122: shift register 322: shift register
123: latch units 323: latch units
Latch at 124: the first and to latch at 324: the first
Latch at 126: the second and to latch at 326: the second
128: level shifter 328: level shifter
130: digital/analog converter 330: digital/analog converter
132: shift register 332: shift register
133: latch units 333: latch units
Latch at 134: the first and to latch at 334: the first
Latch at 136: the second and to latch at 336: the second
138: level shifter 338: level shifter
140: digital/analog converter 340: digital/analog converter
200: 402: the first voltage dividers of source electrode driver
202: 404: the second voltage dividers of power supply unit
204: fall 406: the first comparers of detecting device
206: 408: the second comparers of controller
208: 410: the first phase inverters of passage
210: 412: the second phase inverters of passage
212: 414: the three phase inverters of multiplexer
214: 416: the four phase inverters of output port
216: output port 418: level shifter
220: 420: the five phase inverters of the equal switch-dividing of voltage
300: source electrode driver 422: rejection gate
302: 424: the hex inverters of power supply unit
304: fall detecting device 426: or door.
Specifically execute mode
In order to make narration of the present invention more detailed and complete, can be with reference to the accompanying drawing of following description and cooperation 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 the 2nd figure is by power supply unit 202 power supplies, and source electrode driver 200 comprises at least two channels (channel 208, channel 210...), at least one multiplexer (MUX) 212 at least, at least two output ports (output port 214, output port 216...) couple channel, the equal switch-dividing 220 of voltage, voltage drop detector 204 via multiplexer 212 and power supply unit 202 joins and controller 206 is connected to voltage drop detector 204.The equal switch-dividing 220 of voltage is electrically connected between output port 214 and 216, with when needed, divides equally the voltage of output terminal.The second supply voltage that provides first of noble potential to supply voltage and electronegative potential can be provided power supply unit 202.
Whether positive voltage drop detector 204 can be differentiated power supply conducting or end, and if yes, then produces a reset signal RS.The judgement of power turn-on/end is by detecting the deficiency whether from one of them person of the first supply voltage of power supply unit 202 outputs and the second supply voltage, that is, whether be lower than some critical value.
Reset signal RS can deliver to controller 206 again.Controller 206 produces a control signal CN, and this control signal CN is sent to the equal switch-dividing 220 of voltage, with the equal switch-dividing 220 of cut-off voltage then according to reset signal RS.This control signal CN more is sent to multiplexer, to disconnect being connected of passage and output port, therefore, when the power supply unit 202 that supplies power to source electrode driver just during conduction and cut-off, may abnormal data just can not be sent to output port.So when the power supply unit conduction and cut-off, display can continue to show original image.
Please refer to Fig. 3, Fig. 3 shows the synoptic diagram according to another source electrode driver of preferred embodiment of the present invention.Source electrode driver 300 among Fig. 3 is by power supply unit 302 power supplies, and source electrode driver 300 comprises channel 308 at least and channel 310, multiplexer (MUX) 312, output port 314 is with output port 316, data bus 318, the equal switch-dividing 320 of voltage, voltage drop detector 304 and power supply unit 302 joins and controller 306 is connected to voltage drop detector 304.Output port 314 is coupled to channel 308 and channel 310 with output port 316 via multiplexer 312.The equal switch-dividing 320 of voltage is electrically connected between the output port 314 and output port 316 of source electrode driver 300, with when needed, divides equally the voltage of output terminal.
Each channel has a shift register (322 or 332), a latch units (323 or 333), a level shifter (328 or 338) and a digital/analog converter (DAC) (330 or 340).Each latch units comprises that at least first latchs (324 or 334) and latch (326 or 336) with second and connect.Data transmission and is stored in the latch units on data bus 318, what is more, data are stored in first earlier and latch, and is stored in second again and latchs.
When power supply unit 302 normal power supplies during to source electrode driver 300, data in the channel can input to multiplexer 312, via output port 314 and output port 316, be sent to a display (not shown) again, on display, to show corresponding image.Yet when power supply unit 302 was about to conducting or ends, 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 a reset signal RS, and this reset signal RS is delivered to controller 306, with according to reset signal RS, produces a control signal CN.This control signal CN can be sent to the equal switch-dividing 320 of voltage, with the equal switch-dividing 320 of cut-off voltage.This control signal CN more is sent to multiplexer 312, so that multiplexer 312 is remained on high impedance, is connected with output port 314, output port 316 with disconnection channel 308, channel 310.Therefore, when the power supply unit conduction and cut-off, display can continue to show original image.
Below will describe the structure of voltage drop detector and the generation of reset 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 first voltage divider 402, second voltage divider 404, first comparer 406, second comparer 408, first phase inverter 410, second phase inverter 412, the 3rd phase inverter 414, the 4th phase inverter 416, level shifter 418, the 5th phase inverter 420 and or door 426 at least.Or door 426 comprises that at least rejection gate 422 connects with 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.
First voltage divider 402 produces one first branch pressure voltage V according to the first supply voltage VDDA from power supply unit output
A1, and second voltage divider 404 produces one second branch pressure voltage V according to the second supply voltage VDDD from power supply unit output
D1First comparer 406 is the first branch pressure voltage V relatively
A1With critical voltage V
TH, and produce one first comparison signal RSA.If the first branch pressure voltage V
A1Little, in critical voltage V
TH, then the first comparison signal RSA is a noble potential, expression is because power supply unit is about to conduction and cut-off, so the undertension of power supply unit.If the first branch pressure voltage V
A1Greater than critical voltage V
TH, then the first comparison signal RSA is an electronegative potential, expression power supply unit normal power supply is to source electrode driver.
Similarly, second comparer 408 compares the second branch pressure voltage V
D1With critical voltage V
TH, and produce one second comparison signal RSD.If the second branch pressure voltage V
D1Less than critical voltage V
TH, then the second comparison signal RSD is a noble potential, the expression power supply unit is about to conduction and cut-off.If the second branch pressure voltage V
D1Greater than critical voltage V
TH, then the second comparison signal RSD is an electronegative potential, 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 devices, and second comparer is a lower voltage components.The first branch pressure voltage V
A1, the second branch pressure voltage V
D1And critical voltage V
THSetting all can determine with changing by the user.
Critical voltage V
THProduced by the circuit that can not be subjected to power supply unit output voltage reduction influence easily, for example be can be band ditch 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 are all electronegative potential, then or door 426 outputs one low-potential signal, represent the power supply unit normal power supply to source electrode driver, therefore, reset signal can not produce.On the contrary, if the first comparison signal RSA and/or the second comparison signal RSD are noble potential, then or door 426 outputs one high potential signal, the expression power supply unit is about to conduction and cut-off, and reset signal RS just can produce.
By the invention described above preferred embodiment as can be known, an advantage of the present invention is exactly that the present invention can reduce the undesired image that is shown on the display when the power supply unit conduction and cut-off.
By the invention described above preferred embodiment as can be known, another advantage of the present invention is exactly that whether just the present invention uses voltage drop detector, can detect power supply unit conduction and cut-off, if yes, then produces a reset signal.
Though the present invention discloses as above with a preferred embodiment; right its is not in order to limit the present invention; anyly have the knack of this skill person; without departing from the spirit and scope of the present invention; when can being used for a variety of modifications and variations, so protection scope of the present invention is as the criterion when looking the claim person of defining of the present invention.
Claims (13)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710154232 CN101388188B (en) | 2007-09-11 | 2007-09-11 | Source driver and noise suppression method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710154232 CN101388188B (en) | 2007-09-11 | 2007-09-11 | Source driver and noise suppression method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101388188A CN101388188A (en) | 2009-03-18 |
| CN101388188B true CN101388188B (en) | 2011-05-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 200710154232 Active CN101388188B (en) | 2007-09-11 | 2007-09-11 | Source driver and noise suppression method thereof |
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Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104698393A (en) * | 2013-12-05 | 2015-06-10 | 惠州市德赛西威汽车电子有限公司 | Power detector with automatic muting function and vehicle-borne audio-visual system |
Citations (5)
| 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 |
| CN1604171A (en) * | 2003-09-30 | 2005-04-06 | 三星电子株式会社 | Display driving device, display device and driving method thereof |
| CN1928975A (en) * | 2005-09-06 | 2007-03-14 | 中华映管股份有限公司 | drive unit |
| 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 and its method for eliminating afterimage |
-
2007
- 2007-09-11 CN CN 200710154232 patent/CN101388188B/en active Active
Patent Citations (5)
| 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 |
| CN1604171A (en) * | 2003-09-30 | 2005-04-06 | 三星电子株式会社 | Display driving device, display device and driving method thereof |
| CN1928975A (en) * | 2005-09-06 | 2007-03-14 | 中华映管股份有限公司 | drive unit |
| 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 and its method for eliminating afterimage |
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| Publication number | Publication date |
|---|---|
| CN101388188A (en) | 2009-03-18 |
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