CN101739961B - Source driving device - Google Patents
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- CN101739961B CN101739961B CN2008101735550A CN200810173555A CN101739961B CN 101739961 B CN101739961 B CN 101739961B CN 2008101735550 A CN2008101735550 A CN 2008101735550A CN 200810173555 A CN200810173555 A CN 200810173555A CN 101739961 B CN101739961 B CN 101739961B
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Abstract
The invention discloses a source driving device. The source driving device comprises a plurality of channels and a control module. Each of the channels comprises an output buffer, an output cushion, a driving switch and a charge sharing switch. The control module is used for controlling gate signals of the driving switch or the charge sharing switch in each channel to represent linear change. Therefore, the instantaneous current produced by the source driving device can be reduced so as to reduce the occurrence of electromagnetic interference phenomenon.
Description
Technical field
The present invention relates to LCD, and especially, the present invention relates to a kind of source electrode driving device that is applied to Thin Film Transistor-LCD.
Background technology
In recent years, because display technique is constantly innovated with progressive, various types of display device, for example LCD, plasma scope etc. have appearred also on the market.Because the volume of LCD is far smaller than traditional CRT (cathode-ray tube (CRT), cathode raytube) display, for the narrow and small modern in living space, it is comparatively convenient really to take the little LCD of desk-top space.
For general tft liquid crystal (TFT-LCD) display, its drive unit mainly comprises source electrode driver (source driver or data driver) and gate pole driver (gate driver or scan driver) two parts.Please with reference to Fig. 1, Fig. 1 shows the schematic equivalent circuit of tft liquid crystal panel.
As shown in Figure 1, the sub-pixel of tft liquid crystal panel mainly is to be made up of thin film transistor (TFT) TFT, liquid crystal and capacitor C s.Wherein the effect of thin film transistor (TFT) TFT is as a switch, and scans each bar sweep trace successively by gate pole driver, and it is from top to bottom opened successively.When the thin film transistor (TFT) of a permutation is all opened, promptly write data voltage by source electrode driver.As for capacitor C s parallelly connected with liquid crystal then be to be used for increasing electric capacity, to keep data voltage.
It should be noted that; The effect of source electrode driver is exactly to receive digital signal at a high speed and the process digital-to-analogue conversion and the (level conversion of boosting; Level shift) after the conversion; Signal is delivered on the liquid crystal panel, but speed therebetween wants enough fast, otherwise the conversion rate of picture will be affected.Because liquid crystal panel itself is exactly a very large load, so will to the voltage quasi position of institute's palpus, output stage must have sizable driving force with each sub-pixel charging (or discharge) on the liquid crystal panel at short notice.Therefore, playing the part of considerable role for the Thin Film Transistor-LCD of source electrode driver, high resolving power high-quality and low power consumption for stressing.
Please with reference to Fig. 2, Fig. 2 shows the synoptic diagram of the circuit of output terminal of source electrode driver.As shown in Figure 2, the circuit of output terminal 2 of source electrode driver comprises first passage (channel) 21 altogether to n passages such as n passage 2n, and wherein first passage 21 is corresponding to the first data line Y1 of tft liquid crystal panel; Second channel 21 is corresponding to the second data line Y2 of tft liquid crystal panel; The rest may be inferred, and n passage 2n is corresponding to the n data line Yn of tft liquid crystal panel.With first passage 21 is example, and the voltage that output buffer (outputbuffer) 211 is driven had been sent to output pad (output pad) before 212, can share switch 214 (by Vc control) through driving switch 213 (by Vs control) and another electric charge earlier.
Because the strobe pulse that output buffer is exported input (STB; Strobe input) on every line, all can produce pulse (pulse); In this recurrence interval; Driving switch will be closed to separate output buffer and output pad (output pad), and electric charge is shared switch and will be opened to carry out electric charge and share simultaneously.When this finished recurrence interval, electric charge was shared switch and will be closed to finish electric charge and share, and driving switch then can be opened with driving voltage to output pad simultaneously.
That is to say that source electrode driver can carry out electric charge to be shared when the rising edge of this pulse (rising edge), thereby can produce first momentary current this moment; Source electrode driver can finish when the drop edge of this pulse (falling edge) also that electric charge is shared and output buffer begins driving voltage to output pad, thereby also can produce second momentary current this moment.Therefore; Traditional source electrode driver is owing to first momentary current and big its electromagnetic interference (EMI) (EMI that causes of second momentary current; Electromagnetic interference) phenomenon is serious day by day, even influences the normal operation of thin-film transistor LCD device.
In order to reduce traditional electromagnetic interference (EMI) phenomenon that source electrode driver produced; Adopt the logic gate buffer (logic buffer) of high pressure to drive the rising/fall time (rising/falling time) of sharing the gate signal of switch with controlling and driving switch and electric charge at present, its circuit structure is as shown in Figure 3.
Yet; Under this type of drive, the gate signal that driving switch and electric charge are shared switch is not to change with linear mode, but section changes comparatively mitigation in the front and back of rising/drop edge; But still change very soon at centre portion; It is violent to make driving switch and electric charge share the equivalent change in resistance of switch, thereby will produce sizable momentary current this moment, respectively shown in Fig. 4 (A) and Fig. 4 (B).
In addition; Even the driving force that reduces logic gate buffer is to strengthen rising/fall time that driving switch and electric charge are shared the gate signal of switch; Also can only make the front and back section of rising/drop edge change more mitigation, but the variation of centre portion is still very fast, shown in Fig. 4 (C).Therefore, though momentary current descends to some extent, but still can't effectively avoid the generation of electromagnetic interference (EMI) phenomenon.
Therefore, the present invention provides a source driving device, to address the above problem.
Summary of the invention
The object of the present invention is to provide a source driving device.When this source electrode driving device is used for the drive thin film transistors liquid crystal panel; Can reduce traditional source electrode driving device effectively and produce bigger momentary current; And reduce the electromagnetic interference (EMI) phenomenon that momentary current caused, to guarantee that liquid crystal display panel of thin film transistor (TFT-LCD panel) can normal operation.
The invention provides a source driving device; Comprise a plurality of passages and control module; At least one passage in a plurality of passages comprises the output pad and first switch element, and the output buffer cell is used for drive voltage signal, and first switch element is coupled between output buffer cell and the output pad; When first switch element was opened, voltage signal can be sent to the output pad via first switch element; Control module is coupled to first switch element, and the first gate signal that is used to control first switch element presents linear change.
Be a source driving device according to an advantageous embodiment of the invention.In this embodiment, this source electrode driving device comprises a plurality of passages and the control module that is coupled to the tft liquid crystal panel.Each passage in these a plurality of passages corresponds respectively to the data line on the tft liquid crystal panel.Each passage includes output buffer, output pad, driving switch and electric charge and shares switch.In each passage, before voltage that output buffer drove is being sent to the output pad, will share switch through driving switch and electric charge earlier.This control module is used for controlling the driving switch of each passage and gate signal that electric charge is shared switch and appears and linearly rise or descend, and to reduce momentary current, the phenomenon that reduces electromagnetic interference (EMI) takes place.
In practical application, control module can comprise the high pressure logic gate buffer.The circuit structure of this high pressure logic gate buffer is characterised in that, between specific contact and output terminal, is provided with electric capacity, and controls the electric current to this specific contact charge/discharge through a constant current source, is linearity with the rising/falling waveform of control output end.In fact, the rising/descending slope of linearity rising/falling waveform is relevant with the size of this constant current source and this electric capacity.
According to source electrode driving device of the present invention; In one embodiment; Control module comprises a plurality of transistors and first electric capacity, and first of the first revolution rate of the rising/drop edge of the waveform of the first gate signal and first electric capacity and control module decided current related.
According to source electrode driving device of the present invention, in one embodiment, first switch element is realized with mos field effect transistor.
According to source electrode driving device of the present invention; In one embodiment, passage further comprises: the second switch unit is coupled to contact and common lines between first switch element and output pad; When first switch element was closed, the second switch unit was opened simultaneously to carry out electric charge and is shared.
According to source electrode driving device of the present invention, in one embodiment, the second switch unit is realized with mos field effect transistor.
According to source electrode driving device of the present invention, in one embodiment, control module also is coupled to the second switch unit, and the second gate signal that control module is also controlled said second switch unit presents linear change.
According to source electrode driving device of the present invention, in one embodiment, control module comprises a plurality of transistors and second electric capacity, and second of the second revolution rate of the waveform rising/drop edge of the second gate signal and second electric capacity and control module decided current related.
According to source electrode driving device of the present invention, in one embodiment, passage is coupled to a data line in many data lines on the panel through the output pad, and voltage signal is sent to data line.
According to source electrode driving device of the present invention, in one embodiment, this panel is a liquid crystal display panel of thin film transistor.
Than prior art; The gate signal that the mode of source electrode driving device according to the present invention through linearity adjustment shares driving switch and electric charge with switch is adjusted into linearity; Make the rising/drop edge of gate signal present linear variation; Thereby can reduce traditional source electrode driving device effectively and produce bigger momentary current, and reduce the electromagnetic interference (EMI) phenomenon that momentary current caused.
In addition; Because source electrode driving device can be through adjusting the revolution rate (slew rate) that the size of deciding electric current and electric capacity changes the rising/drop edge of gate signal; Thereby also can be used for adjusting the length of the rising/fall time of gate signal; And do not have direct relation with the load of tft liquid crystal panel, more can not receive the influence of load size.
Can further be understood through following embodiment and accompanying drawing about advantage of the present invention and spirit.
Description of drawings
Fig. 1 shows the schematic equivalent circuit of tft liquid crystal panel in the prior art.
Fig. 2 shows the synoptic diagram of the circuit of output terminal of source electrode driver in the prior art.
Fig. 3 shows the circuit structure of high pressure logic gate buffer used in the prior art.
Fig. 4 (A) and Fig. 4 (B) illustrate the effect that waveform produced of being shared the gate signal of switch by the high pressure logic gate buffer among Fig. 3 for driving switch and electric charge respectively.
Fig. 4 (C) has compared with the effect that waveform produced of the more weak second high pressure logic gate buffer of the stronger first high pressure logic gate buffer of driving force and driving force for the gate signal of driving switch.
Fig. 5 shows the synoptic diagram according to the circuit of output terminal of the source electrode driving device of a specific embodiment of the present invention.
Fig. 6 shows the circuit structure of a kind of high pressure logic gate buffer proposed by the invention.
Fig. 7 (A) and Fig. 7 (B) show the effect that rising waveform produced of being shared the gate signal of switch by the high pressure logic gate buffer among Fig. 6 for driving switch and electric charge respectively.
Fig. 8 has compared high pressure logic gate buffer and traditional high pressure logic gate buffer among Fig. 3 among Fig. 6 respectively for the effect that rising waveform produced of the gate signal of driving switch.
Fig. 9 has compared the high pressure logic gate buffer among Fig. 6 and traditional high pressure logic gate buffer among Fig. 3 are shared the gate signal of switch respectively for electric charge the effect that rising waveform produced.
Figure 10 shows the circuit structure of another kind of high pressure logic gate buffer proposed by the invention.
Figure 11 (A) and Figure 11 (B) show the effect that falling waveform produced of being shared the gate signal of switch by the high pressure logic gate buffer among Figure 10 for driving switch and electric charge respectively.
Figure 12 has compared high pressure logic gate buffer and traditional high pressure logic gate buffer among Figure 10 respectively for the effect that falling waveform produced of the gate signal of driving switch.
Figure 13 has compared the high pressure logic gate buffer among Figure 10 and traditional high pressure logic gate buffer are shared the gate signal of switch respectively for electric charge the effect that falling waveform produced.
Embodiment
The present invention provides a source driving device.When this source electrode driving device is used for the drive thin film transistors liquid crystal panel; Can reduce traditional source electrode driving device effectively and produce bigger momentary current; And reduce the electromagnetic interference (EMI) phenomenon that momentary current caused, can normal operation to guarantee liquid crystal display panel of thin film transistor.
Next, will do simple the introduction with regard to the conception and the principle of source electrode driving device proposed by the invention.Generally speaking, the performance of source electrode driving device quality is mainly shared the equivalent resistance of switch with driving force, driving switch and the electric charge of its output buffer and the factors such as RC load size on the panel are relevant.Suppose the driving force of output buffer and the RC load on the panel all fixedly the time, the equivalent resistance that the performance of source electrode driving device promptly mainly receives driving switch and electric charge to share switch influences.
For example, when driving switch had less equivalent resistance, output buffer can charge to target voltage values with the RC load on the panel with bigger electric current in short output delay time (output delay time).Yet the equivalent resistance of less driving switch will cause bigger momentary current and cause more serious electromagnetic interference (EMI) phenomenon.Likewise, the equivalent resistance that less electric charge is shared switch can have bigger electric current to carry out electric charge in the same time to share, and makes the enhancing efficiency that electric charge is shared, thereby can save more electric power the IC temperature is reduced.But the momentary current that the thing followed is bigger also causes more serious electromagnetic interference (EMI) phenomenon.
Generally speaking; No matter be that driving switch or electric charge are shared switch and realized by mos field effect transistor (for example CMOS or N/PMOS) mostly, thus the size of its equivalent resistance and transistorized breadth length ratio (W/L) with and the length of rising/fall time of gate signal relevant.For example, when the transistorized breadth length ratio of certain switch was big more, the equivalent resistance of this switch was promptly more little, made very big momentary current to produce and caused serious electromagnetic interference (EMI) phenomenon.Otherwise if the transistorized breadth length ratio of certain switch is more little, the equivalent resistance of this switch is promptly big more, thereby momentary current will diminish, and the related electromagnetic interference (EMI) phenomenon that makes significantly reduces.
In addition; Because the gate signal is not when rising to high levle or dropping to low level fully fully; The equivalent resistance of switch will change along with the change of gate signal, if the rising/fall time of the gate signal of certain switch is longer, the variation of the equivalent resistance of this switch is comparatively slow; Make momentary current less, relatedly make that the electromagnetic interference (EMI) phenomenon is more not obvious.Otherwise if the rising/fall time of the gate signal of certain switch is shorter, the variation of the equivalent resistance of switch is comparatively rapid, makes momentary current bigger, thereby will cause serious electromagnetic interference (EMI) phenomenon.
In practical application, owing to receive the restriction of output delay time and power saving critical specifications such as (IC temperature), it is quite limited really that driving switch and electric charge are shared the scope that the transistorized breadth length ratio of switch can modulation.Therefore, reduce the seemingly unique feasible method of electromagnetic interference (EMI) phenomenon the rising/fall time of the gate signal through CS.
Yet; Under the type of drive of traditional high pressure logic gate buffer (as shown in Figure 3), the gate signal that driving switch and electric charge are shared switch is not to present linear change, but section changes more slow in the front and back of rising/drop edge; But still change very soon at centre portion; It is violent to make driving switch and electric charge share the equivalent change in resistance of switch, thereby will produce sizable momentary current, shown in Fig. 4 (A) and Fig. 4 (B).Even the driving force (for example replacing the first stronger high pressure logic gate buffer of driving force originally with the second more weak high pressure logic gate buffer of driving force) that reduces logic gate buffer is to prolong the rising/fall time of gate signal; Still only can make the front and back section of rising/drop edge change more mitigation; The variation of centre portion is still very fast; Thereby the electromagnetic interference (EMI) phenomenon still can't effectively solve, shown in Fig. 4 (C).
In order to reduce traditional electromagnetic interference (EMI) phenomenon that source electrode driving device produced effectively; The present invention proposes a kind of new source electrode driving device; Hope circuit structure through new logic gate buffer; The gate signal that controlling and driving switch and electric charge are shared switch presents the linear phenomenon that rises or descend, and makes momentary current to reduce, the electromagnetic interference (EMI) phenomenon that related minimizing source electrode driving device is produced.
A specific embodiment according to the present invention is a source driving device.Please with reference to Fig. 5, Fig. 5 shows the synoptic diagram of the circuit of output terminal of this source electrode driving device.As shown in Figure 5; The circuit of output terminal of supposing source electrode driving device 5 comprises three passage, common lines 54 and control modules 55 that are coupled to tft liquid crystal panel 8 such as first passage 51, second channel 52 and third channel 53 altogether, and wherein first passage 51, second channel 52 and third channel 53 correspond respectively to first data line 81, second data line 82 and the 3rd data line 83 on the tft liquid crystal panel 8.
In fact, the number of active lanes of source electrode driving device 5 is relevant with the data line number on the tft liquid crystal panel 8, does not exceed with this example., and known because not within the scope of the invention as for other parts of source electrode driving device 5, thereby do not given unnecessary details at this by those skilled in the art.
In this embodiment, first passage 51 includes first output buffer 511, first output pad 512, first driving switch 513 and first electric charge and shares switch 514; Second channel 52 includes second output buffer 521, second output pad 522, second driving switch 523 and second electric charge and shares switch 524; Third channel 53 includes the 3rd output buffer 531, the 3rd output pad the 532, the 3rd driving switch 533 and tricharged and shares switch 534.Wherein first electric charge is shared switch 514, second electric charge and is shared switch 524 and tricharged and share switch 534 and all be coupled on the common lines 54.
It should be noted that; First driving switch 513, second driving switch 523 and the 3rd driving switch 533 are coupled to control module 55 respectively and are controlled by control voltage Vs (1), Vs (2) and Vs (3); And control voltage Vs (1), Vs (2) and Vs (3) are exported by control module 55 (circuit structure of new high pressure logic gate buffer for example proposed by the invention), and the gate signal that is used to control first driving switch 513, second driving switch 523 and the 3rd driving switch 533 presents linear change.Share switch 514, second electric charge as for first electric charge and share switch 524 and tricharged and share switch 534 and also be coupled to control module 55 respectively and control, and control voltage Vc (1), Vc (2) and Vc (3) also by 55 outputs of control module by control voltage Vc (1), Vc (2) and Vc (3).
In this embodiment, the voltage that output buffer drove of each passage will be shared switch through the driving switch and the electric charge of this passage earlier before being sent to the output pad of this passage.Examination is an example with first passage 51, and first voltage that first output buffer 511 is driven will be shared switch 514 through first driving switch 513 and first electric charge earlier before being sent to the first output pad 512.
When first output buffer 511 exported first when dodging the control input signal and producing pulse; In this recurrence interval; First driving switch 513 will be closed to separate first output buffer 511 and the first output pad 512, and simultaneously, first electric charge is shared switch 514 and will be opened to carry out electric charge and share.Therefore, in this recurrence interval first output buffer 511 can't driving voltage to the first output pad 512, but carry out program that electric charge shares to save electric power and to reduce the temperature of IC.
When this recurrence interval finishes; First electric charge is shared switch 514 and will be closed to finish the program that electric charge is shared; Simultaneously, 513 of first driving switchs can be opened the output buffer 511 of winning can be exported pad 512 and be sent to first data line 81 through the first output pad 512 by driving voltage to the first.
Likewise, in second channel 52, second voltage that second output buffer 521 is driven also can be shared switch 524 through second driving switch 523 and second electric charge earlier before being sent to the second output pad 522.In the second sudden strain of a muscle control recurrence interval that input signal produced that second output buffer 521 is exported; Second driving switch 523 will be closed to separate second output buffer 521 and the second output pad 522; Simultaneously, second electric charge is shared switch 524 and will be opened to carry out electric charge and share.When this recurrence interval finished, second electric charge is shared switch 524 will close the program of sharing with the end electric charge, and simultaneously, 523 of second driving switchs can be opened with driving voltage to the second output pad 522 and be sent to second data line 82.Situation as for third channel 53 is also identical, thereby repeats no more at this.
With first passage 51 is example, and source electrode driving device 5 can carry out electric charge when first dodges the rising edge of control this pulse that input signal produced shares, thereby will produce first momentary current this moment; Source electrode driving device 5 also can finish electric charge and share when the drop edge of this pulse.At this moment, because first output buffer, 511 beginning driving voltage to the first output pads 512, thereby also can produce second momentary current.
Yet; Be different from traditional source electrode driver and cause serious electromagnetic interference (EMI) phenomenon owing to the first bigger momentary current and second momentary current; Even influence the normal operation of thin-film transistor LCD device; The present invention is directed to control module 55 and propose a kind of circuit structure of brand-new high pressure logic gate buffer; The gate signal of sharing switch through each driving switch of control Control of Voltage that this circuit structure produced and each electric charge appears and linearly rises or descend, and to reduce momentary current, the phenomenon that reduces electromagnetic interference (EMI) takes place.Next, will introduce to the circuit structure of high pressure logic gate buffer proposed by the invention.
Please with reference to Fig. 6, Fig. 6 shows a kind of circuit structure of high pressure logic gate buffer.When driving switch and electric charge were shared switch and realized by NMOS, this circuit structure was used for controlling and driving switch and electric charge and shares the rising waveform of the gate signal of switch and can present linear situation about rising, respectively shown in Fig. 7 (A) and Fig. 7 (B).It should be noted that this circuit structure can't change into linearity with the falling waveform that driving switch and electric charge are shared the gate signal of switch.
In this circuit structure; Owing between contact VP and output terminal OUT, be provided with capacitor C r; And control the electric current of docking point VP discharge through constant current source Ir; Thereby can make the rising waveform of output terminal OUT become linearity, its rate of rise is relevant with the size of constant current source Ir and capacitor C r, also is the revolution rate of rising waveform.For example, as constant current source Ir bigger or capacitor C r more hour, its rate of rise is promptly steep more; When more little or capacitor C r was big more as constant current source Ir, its rate of rise was promptly slow more.
In addition, through this circuit structure, the user can adjust the revolution rate of linear rising waveform according to the actual requirements.For example, if the factor of user's main consideration is for reducing the electromagnetic interference (EMI) phenomenon, then the revolution rate of linear rising waveform is low more good more, also is that linear rising waveform is good more more gently, can realize through reducing constant current source Ir or increasing capacitor C r this moment.Yet if the user hopes is that output delay time is short more, the revolution rate of linear rising waveform is high more naturally good more, also is that linear rising waveform is precipitous more good more, can realize through the capacitance that increases constant current source Ir or reduce capacitor C r this moment.
Please with reference to Fig. 8, Fig. 8 has compared high pressure logic gate buffer and the traditional high pressure logic gate buffer among Fig. 3 among Fig. 6 respectively for the effect that rising waveform produced of the gate signal of driving switch.As shown in Figure 8, because the rising waveform of the gate signal of controlling and driving switch presents linear the rising, the momentary current that is therefore produced is significantly less than traditional high pressure logic gate buffer according to high pressure logic gate buffer of the present invention.In addition; In reaching the process of target voltage; (Y1) curve is obviously comparatively mild than V (Y1) curve corresponding to traditional high pressure logic gate buffer corresponding to the V ' of high pressure logic gate buffer of the present invention; More unmatched back section changes mitigation, but takes place in the phenomenon that centre portion still changes very soon.
Please with reference to Fig. 9, Fig. 9 has compared the high pressure logic gate buffer among Fig. 6 and the traditional high pressure logic gate buffer among Fig. 3 are shared the gate signal of switch respectively for electric charge the effect that rising waveform produced.As shown in Figure 9, because sharing the rising waveform of the gate signal of switch, the control electric charge presents linear the rising according to high pressure logic gate buffer of the present invention, the momentary current that is therefore produced is obviously less than traditional high pressure logic gate buffer.In addition; In reaching the process of target voltage; (Y1) curve is obviously comparatively mild than V (Y1) curve corresponding to traditional high pressure logic gate buffer corresponding to the V ' of high pressure logic gate buffer of the present invention; More unmatched back section changes mitigation, but takes place in the phenomenon that centre portion still changes very soon.
Please with reference to Figure 10, Figure 10 shows the circuit structure of another kind of high pressure logic gate buffer proposed by the invention.When driving switch and electric charge were shared switch and realized by PMOS, this circuit structure can be used for controlling and driving switch and electric charge and shares the falling waveform of the gate signal of switch and can present linear decline, respectively shown in Figure 11 (A) and Figure 11 (B).It should be noted that the rising waveform that this circuit structure can't be simultaneously shared the gate signal of switch with driving switch and electric charge also changes into linearity.
In this circuit structure; Owing between contact VN and output terminal OUT, be provided with capacitor C r; And control the electric current of docking point VN charging through constant current source Ir; Thereby can make the falling waveform of output terminal OUT become linearity, its descending slope is relevant with the size of constant current source Ir and capacitor C r, also is the revolution rate of falling waveform.For example, as constant current source Ir bigger or capacitor C r more hour, its descending slope is promptly steep more; When more little or capacitor C r was big more as constant current source Ir, its descending slope was promptly slow more.
In addition, through this circuit structure, the user can adjust the revolution rate of linear falling waveform according to the actual requirements.For example, if want to reduce the electromagnetic interference (EMI) phenomenon, then linear falling waveform is good more more gently, thereby can realize through reducing constant current source Ir or increasing capacitor C r; If want output efficiency faster, then linear falling waveform is precipitous more good more, thereby can realize through the capacitance that increases constant current source Ir or minimizing capacitor C r.
Please with reference to Figure 12, Figure 12 has compared high pressure logic gate buffer and traditional high pressure logic gate buffer among Figure 10 respectively for the effect that falling waveform produced of the gate signal of driving switch.Shown in figure 12 and since according to high pressure logic gate buffer of the present invention can the controlling and driving switch the falling waveform of gate signal be linearity, thereby the momentary current that it produced is obviously less than traditional high pressure logic gate buffer.In addition; In reaching the process of target voltage; Suppose that output delay time is identical; (Y1) curve is obviously comparatively mild than V (Y1) curve corresponding to traditional high pressure logic gate buffer corresponding to the V ' of high pressure logic gate buffer of the present invention, and more unmatched back section changes and relaxes, but still changes very soon the phenomenon generation at centre portion.
Please with reference to Figure 13, Figure 13 has compared the high pressure logic gate buffer among Figure 10 and traditional high pressure logic gate buffer are shared the gate signal of switch respectively for electric charge the effect that falling waveform produced.Shown in figure 13, be linearity according to high pressure logic gate buffer of the present invention because the control electric charge is shared the falling waveform of the gate signal of switch, thereby the momentary current of its generation is obviously less than traditional high pressure logic gate buffer.In addition; In reaching the process of target voltage; (Y1) curve is obviously comparatively mild than V (Y1) curve corresponding to traditional high pressure logic gate buffer corresponding to the V ' of high pressure logic gate buffer of the present invention; Section does not change mitigation before and after more can equally with prior art not occurring, but centre portion still changes quickish phenomenon.
In sum; Compared with prior art; The gate signal that the mode of source electrode driving device according to the present invention through linearity adjustment shares driving switch and electric charge with switch is adjusted into linearity; Make the rising/drop edge of gate signal present linear variation, thereby can reduce traditional source electrode driving device effectively and produce bigger momentary current, and the minimizing electromagnetic interference (EMI) phenomenon that momentary current caused.
In addition; Because source electrode driving device can be through adjusting the revolution rate that the size of deciding electric current and electric capacity changes the rising/drop edge of gate signal; Thereby also can be used for adjusting the length of the rising/fall time of gate signal; And do not have direct relation with the load of tft liquid crystal panel, more can not receive the influence of load size.
Through the detailed description of above preferred specific embodiment, hope can be known description characteristic of the present invention and spirit more, and is not to come scope of the present invention is limited with the above-mentioned preferred specific embodiment that is disclosed.On the contrary, its objective is that hope can and be equal to arrangement with various changes and be covered by in the scope of claim of the present invention.Therefore, the scope of claim of the present invention should be done the broadest explanation according to above-mentioned explanation, to cause it to contain all possible change and to be equal to arrangement.
The primary clustering symbol description
2: circuit of output terminal 21～2n: first passage to the n passage
211: output buffer 212: the output pad
213: driving switch 214: electric charge is shared switch
5: source electrode driving device 51: first passage
52: second channel 53: third channel
54: common lines 8: the tft liquid crystal panel
82: the second data lines of 81: the first data lines
511: the first output buffers of 83: the three data lines
513: the first driving switchs of 512: the first output pads
Electric charge was shared 521: the second output buffers of switch in 514: the first
523: the second driving switchs of 522: the second output pads
Electric charge was shared 531: the three output buffers of switch in 524: the second
533: the three driving switchs of 532: the three output pads
Tricharged was shared switch 55 in 534: the: control module
TFT: thin film transistor (TFT) VP, VN: contact
IN: input end OUT: output terminal
Cr, Cs: capacitor I r: constant current source
Y1～Yn: first data line to the n data line
Vs, Vs ', Vs (1)～Vs (n): the control voltage of controlling and driving switch
Vc, Vc ', Vc (1)～Vc (n): the control electric charge is shared the control voltage of switch
V ' is (Y1): corresponding to the charge/discharge curve of conventional high-tension logic gate buffer
V (Y1): corresponding to the charge/discharge curve of high pressure logic gate buffer of the present invention.
Claims (6)
1. a source driving device comprises:
A plurality of passages, at least one passage in said a plurality of passages comprises:
The output pad;
The output buffer cell is used for drive voltage signal; And
First switch element is coupled between said output buffer cell and the said output pad, and when said first switch element was opened, said voltage signal can be sent to said output pad via said first switch element; And
Control module is coupled to said first switch element, and the first gate signal that is used to control said first switch element presents linear change,
Wherein, said control module comprises a plurality of transistors and first electric capacity, and first of the first revolution rate of the rising/drop edge of the waveform of the said first gate signal and said first electric capacity and said control module decided current related,
Wherein, said passage further comprises:
The second switch unit is coupled to contact and common lines between said first switch element and said output pad, and when said first switch element was closed, said second switch unit was opened simultaneously to carry out electric charge and shared.
2. source electrode driving device according to claim 1, wherein, said first switch element is realized with mos field effect transistor.
3. source electrode driving device according to claim 1, wherein, said second switch unit is realized with mos field effect transistor.
4. source electrode driving device according to claim 1, wherein, said control module also is coupled to said second switch unit, and the second gate signal that said control module is also controlled said second switch unit presents linear change,
Wherein, said control module comprises a plurality of transistors and second electric capacity, and second of the second revolution rate of the waveform rising/drop edge of the said second gate signal and said second electric capacity and said control module decided current related.
5. source electrode driving device according to claim 1, wherein, said passage is coupled to a data line in many data lines on the panel through said output pad, and said voltage signal is sent to said data line.
6. source electrode driving device according to claim 5, wherein, said panel is a liquid crystal display panel of thin film transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008101735550A CN101739961B (en) | 2008-11-06 | 2008-11-06 | Source driving device |
Applications Claiming Priority (1)
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| CN102262850B (en) * | 2011-08-02 | 2013-04-10 | 华映视讯（吴江）有限公司 | Display device |
| JP6925605B2 (en) * | 2017-01-12 | 2021-08-25 | 株式会社Ｊｏｌｅｄ | Drive circuit |
| CN108806624B (en) * | 2017-04-26 | 2021-08-06 | 矽创电子股份有限公司 | Display device and driving circuit thereof |
| CN111696462B (en) * | 2019-03-14 | 2023-07-21 | 奇景光电股份有限公司 | Output buffer and method of operating the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1855211A (en) * | 2005-04-27 | 2006-11-01 | 日本电气株式会社 | Active matric display device and its drive method |
| CN101237233A (en) * | 2007-01-27 | 2008-08-06 | 三星电子株式会社 | Output buffer with a controlled slew rate offset and source driver including the same |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1855211A (en) * | 2005-04-27 | 2006-11-01 | 日本电气株式会社 | Active matric display device and its drive method |
| CN101237233A (en) * | 2007-01-27 | 2008-08-06 | 三星电子株式会社 | Output buffer with a controlled slew rate offset and source driver including the same |
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| Title |
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| JP特开平7-235844A 1995.09.05 |
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