CN101707048A - Source driver circuit of thin film transistor - Google Patents
Source driver circuit of thin film transistor Download PDFInfo
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- CN101707048A CN101707048A CN200910051942A CN200910051942A CN101707048A CN 101707048 A CN101707048 A CN 101707048A CN 200910051942 A CN200910051942 A CN 200910051942A CN 200910051942 A CN200910051942 A CN 200910051942A CN 101707048 A CN101707048 A CN 101707048A
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Abstract
The invention provides a source driver circuit of a thin film transistor. The source driver circuit comprises an amplification circuit used for amplifying gradation voltage, and a switching circuit used for switching between the gradation voltage of a current channel and the gradation voltage of an adjacent channel. The source driver circuit is characterized in that the gradation voltage is output to the amplification circuit after passing through the switching circuit. The invention also provides a corresponding control method and a display device. By arranging the amplification circuit behind the switching circuit, the source driver circuit can reduce the power consumption of the switching circuit consisting of MOS pipes, thus reducing energy consumption and improving the response speed of the circuit.
Description
Technical field
The present invention relates to Thin Film Transistor-LCD, especially the source driver circuit of Thin Film Transistor-LCD.
Background technology
Thin Film Transistor-LCD (TFT-LCD) has light weight, panelized, low-power consumption, radiationless, advantage such as display quality is good.In recent years, perfect gradually along with the TFT manufacturing technology, the raising of finished product rate and the generation of some new technologies, the TFT LCD has had very big improvement at aspects such as response time, contrast, brightness, visible angles.Utilize the LCD of the active matrix-type liquid crystal display device of TFT, be widely used in fields such as mobile phone, vehicular display, projection TV, computing machine, military aviations as high image quality.Along with the increase of TFT liquid crystal display displays area and the raising of resolution, the increase of the number of scanning lines requires the time of write signal to shorten; Whole driving circuit, especially source drive area partly also can increase significantly simultaneously.
Fig. 5 shows the active driving array of Thin Film Transistor-LCD, and wherein, the circuit that drives active matrix is source electrode drive circuit and gate driver circuit.Particularly, the effect of source electrode drive circuit is that source electrode line (data line) is applied grayscale voltage (target voltage), and the effect of gate driver circuit is the conducting and the disconnection of gauge tap, in each basic display unit, the TFT equivalence is a switch, the grid G of switch transistor T FT links to each other with gate line, and source S links to each other with source electrode line, and drain D links to each other with liquid crystal pixel.Mode according to a delegation during work scans grid successively, whenever scan a gate line, coupled TFT is in conducting state simultaneously, load the control that required voltage discharges and recharges the memory capacitance that connects the TFT drain electrode at corresponding source electrode line, the electric field between the liquid crystal two substrates of how much changing by the control capacitance stored charge, thereby reach control liquid crystal deflecting element angle, realize finally wanting the display effect that obtains.
More specifically, the TFT device is consistent with the principle of work of MOS device, and unique difference is that the semiconductor material of MOS device is a monocrystalline, and the semiconductor material of TFT is a thin film transistor (TFT).TFT plays the effect of electronic switch in procedure for displaying, the grid of TFT all is connected on the horizontal scanning line, the source electrode of TFT is connected on the source drive line, the drain electrode of TFT is connected on the subpixel electrode of liquid crystal, like this, when the voltage that is added in horizontal scanning line during for the gate voltage of this row, all TFT of this row are by gating, and the signal on the source drive line just can be added to driving liquid crystal work on the subpixel electrode of liquid crystal by TFT.As shown in Figure 5, a lot of single pixels fitly are arranged on the panel, grid separately all is connected on the gate driver circuit, the waveform that gate driving is sent, TFT with each row opens in regular turn, so just can allow source electrode drive circuit drive the display dot of a corresponding full line simultaneously, it is discharged and recharged required separately voltage, each pixel will demonstrate different gray scales like this.After this delegation's charging finished, gate driver circuit was just closed the voltage of this journey, drove next line TFT then and opened, and was discharged and recharged by the picture element of identical row's source electrode drive circuit to next line again.So circulation is gone down, and when the picture element of the last column of having substituted the bad for the good, just begins discharging and recharging of a new round again since first row again.
Therefore, in the TFT display system, source electrode drive circuit has important effect, it directly influences the display effect of display system, major parameters such as power consumption. at the increasing trend of present display system, the research low-power consumption, the source electrode drive circuit of high reaction velocity has great importance. in the prior art, source electrode drive circuit generally includes amplifying circuit and commutation circuit, wherein, commutation circuit when adjacency channel switches is placed on after the amplifying circuit, because commutation circuit generally is made of NMOS pipe and PMOS pipe, so when output voltage during near input voltage, it is very big that the equiva lent impedance of metal-oxide-semiconductor can become, and had a strong impact on the reaction velocity of circuit like this.
Summary of the invention
At defective of the prior art, the objective of the invention is provides a kind of thin film transistor (TFT) source electrode drive circuit by the change to amplifying circuit and commutation circuit annexation.
According to an aspect of the present invention, provide a kind of source driver circuit of thin film transistor, comprise amplifying circuit, it is used for grayscale voltage is amplified; And commutation circuit, it is used for switching between the grayscale voltage to this passage grayscale voltage and adjacency channel, it is characterized in that, and grayscale voltage exports described amplifying circuit to after by described commutation circuit.
Preferably, described amplifying circuit comprises first amplifier and second amplifier, and wherein, described first amplifier and described second amplifier are used for grayscale voltage is amplified output.
Preferably, described first amplifier and described second amplifier adopt the rail-to-rail amplifier.
Preferably, the in-phase end of described first amplifier connects first output terminal of described commutation circuit, and end of oppisite phase connects its output terminal; The in-phase end of described second amplifier connects second output terminal of described commutation circuit, and end of oppisite phase connects its output terminal.
Preferably, be connected in series the first transistor respectively between the first input end of described commutation circuit and first output terminal and second output terminal, be connected in series transistor seconds respectively between second input end of described commutation circuit and first output terminal and second output terminal.
Preferably, described the first transistor adopts the PMOS pipe, and described transistor seconds adopts the NMOS pipe.
Preferably, described the first transistor adopts cmos transmission gate, and described transistor seconds adopts cmos transmission gate.
Preferably, first output terminal of described commutation circuit is connected to the in-phase end of described first amplifier, and second output terminal of described commutation circuit is connected to the in-phase end of described second amplifier.
According to another aspect of the present invention, also provide a kind of control method that is used for source driver circuit of thin film transistor, it is characterized in that, comprise step: export grayscale voltage to amplifying circuit after by commutation circuit.
According to a further aspect of the invention, provide a kind of thin film transistor liquid crystal display device, it is characterized in that, comprise described TFT source electrode drive circuit provided by the invention.
Preferably, described thin film transistor liquid crystal display device comprises grayscale voltage generating apparatus, amplifying circuit, commutation circuit and active driving array at least, wherein, described grayscale voltage generating apparatus generates grayscale voltage and transfers to described commutation circuit, grayscale voltage transfers to described amplifying circuit and amplifies after described commutation circuit, the grayscale voltage after described then amplifying circuit will amplify exports active driving array to.
The present invention is by being placed on described amplifying circuit after the described commutation circuit, in other words, export described amplifying circuit to after making grayscale voltage by described commutation circuit, the output terminal of amplifier directly connects with output resistance in the described amplifying circuit, thereby institute's power consumed on the described commutation circuit that can reduce to constitute by metal-oxide-semiconductor, can reduce energy consumption like this, improve the reaction velocity of circuit.Further, the display device that comprises thin film transistor (TFT) source electrode drive circuit provided by the invention can reduce power consumption compared to existing technology, improves the reaction velocity of display device, thereby improves the display effect of display device.
Description of drawings
By reading the detailed description of non-limiting example being done with reference to the following drawings, it is more obvious that other features, objects and advantages of the present invention will become:
Fig. 1 illustrates the structural representation of thin film transistor (TFT) source electrode drive circuit in the prior art;
Fig. 2 illustrates according to the first embodiment of the present invention, the structural representation of source driver circuit of thin film transistor;
Fig. 3 illustrates according to the first embodiment of the present invention, the structural representation of the described commutation circuit that source driver circuit of thin film transistor comprises;
Fig. 4 illustrates according to one of the first embodiment of the present invention and changes example, the structural representation of the described commutation circuit that source driver circuit of thin film transistor comprises; And
Fig. 5 illustrates the active driving array of Thin Film Transistor-LCD.
Embodiment
Fig. 1 illustrates the structural representation of source driver circuit of thin film transistor in the prior art.Particularly, existing thin film transistor (TFT) source electrode drive circuit generally includes amplifying circuit 1 and commutation circuit 2, and wherein, described commutation circuit 2 was placed on after the amplifying circuit 1 when adjacency channel switched, that is to say that described amplifying circuit 1 outputs to described commutation circuit 2 after grayscale voltage is amplified.More specifically, described amplifying circuit 1 comprises P type amplifier 11 and N type amplifier 12, and described commutation circuit 2 comprises first input port 21, first delivery outlet 22, second input port 23 and second delivery outlet 24.Wherein, the in-phase end of described P type amplifier 11 is as the input port of grayscale voltage, and output terminal is connected to the first input end 21 of described commutation circuit 2 as the delivery outlet of grayscale voltage, and end of oppisite phase is connected with output terminal; The in-phase end of described N type amplifier 12 is as the input port of grayscale voltage, and output terminal is connected to second input end 23 of described commutation circuit 2 as the delivery outlet of grayscale voltage, and end of oppisite phase is connected with output terminal.Described commutation circuit 2 is transmitted the grayscale voltage by described first input end 21 and 23 inputs of second input end under the control of switching signal, export grayscale voltage to source electrode line by described first output terminal 22 and second output terminal 24 then, example is source electrode line S1 and S2 as shown in Figure 5.
Those skilled in the art understand, described commutation circuit 2 generally is made of with the PMOS pipe the NMOS pipe, when output voltage during near input voltage, be equivalent to Vds (promptly being added in the voltage between metal-oxide-semiconductor drain electrode and the source electrode) and diminish, this moment, the equiva lent impedance of metal-oxide-semiconductor can become very big.In the circuit working process, on metal-oxide-semiconductor, just consume extra power consumption like this, and after the impedance change greatly, had a strong impact on the reaction velocity of circuit.
Fig. 2 illustrates according to the first embodiment of the present invention, the structural representation of source driver circuit of thin film transistor.Particularly, in the present embodiment, described source electrode drive circuit comprises commutation circuit 2 and amplifying circuit 3, wherein, described commutation circuit 2 is used for switching between the grayscale voltage to this passage grayscale voltage and adjacency channel, described amplifying circuit 3 is used for grayscale voltage is amplified, grayscale voltage exports described amplifying circuit 3 to after by described commutation circuit 2, more specifically, described commutation circuit 2 comprises first input port 21, first delivery outlet 22, second input port 23 and second delivery outlet 24, described amplifying circuit 3 comprise first amplifier 31 and second amplifier 32.
Wherein, the first input end 21 of described commutation circuit 2 and second input end 23 be as the input port of grayscale voltage, described commutation circuit 2 under the control of switching signal by described first output terminal 22 and second output terminal 24 respectively to described first amplifier 31 and second amplifier, 32 output gray level voltages.Further, the in-phase end of described first amplifier 31 connects first output terminal 22 of described commutation circuit 2, and end of oppisite phase connects output terminal, and output terminal exports grayscale voltage to source electrode line as the delivery outlet of grayscale voltage; The in-phase end of described second amplifier 32 connects second output terminal 24 of described commutation circuit 2, and end of oppisite phase connects output terminal, and output terminal exports grayscale voltage to source electrode line as the delivery outlet of grayscale voltage.
Those skilled in the art understand, because described commutation circuit 2 is positioned over before the described amplifying circuit 3, be that grayscale voltage exports described amplifying circuit 3 to after by described commutation circuit 2, the output terminal of amplifier directly connects with output resistance in the described amplifying circuit 3, therefore can overcome above-mentioned deficiency of the prior art. in other words, in the present embodiment, the described commutation circuit 2 of comparing with described amplifying circuit 3 is placed in a side (position) that more approaches grayscale voltage generative circuit or similar circuit device, the described amplifying circuit 3 of comparing with described commutation circuit 2 in other words is placed in and more approaches active driving array. and such circuit connecting mode constitutes essential distinction with prior art, does not repeat them here.
Preferably, described first amplifier 31 and described second amplifier 32 adopt the rail-to-rail amplifier.Those skilled in the art understand, by the DC characteristic of amplifier as can be known, by the suitably DC current and the component characteristic parameter of selective amplifier, can make the higher limit of its input range approach supply voltage VDD for N type amplifier, but the lower limit current potential is far apart from the ground reference point; And can make the lower limit of its input range approach the ground reference point for P type amplifier, and higher limit is far apart from supply voltage VDD, and adopting the track to track amplifier that the voltage power supply range limit value of amplifier is expanded near supply voltage, lower limit is reference point closely; So just can better meet the requirement that drives the liquid crystal source electrode line.
Fig. 3 illustrates according to the first embodiment of the present invention, the structural representation of the described commutation circuit that source driver circuit of thin film transistor comprises.Particularly, in the present embodiment, be connected with PMOS pipe 41 between described first input end 21 and described first output terminal 22, be connected with PMOS pipe 42 between described first input end 21 and described second output terminal 24, be connected with NMOS pipe 43 between described second input end 23 and described first output terminal 22, be connected with NMOS pipe 44 between described second input end 23 and described second output terminal 24, wherein, described PMOS pipe 41, PMOS pipe 42, NMOS pipe 43 and NMOS pipe 44 conducting or end under the control of switching signal.To export from described first output terminal 22 by the grayscale voltage of described first input end 21 inputs if need, and the grayscale voltage by 23 inputs of described second input end is exported from described second output terminal 24, then the grid of described PMOS pipe 41 is added low-voltage by switch-over control signal, grid to described PMOS pipe 42 adds high voltage, grid to described NMOS pipe 43 adds low-voltage, and the grid of described NMOS pipe 44 is added high voltage; To export from described second output terminal 24 by the grayscale voltage of described first input end 21 inputs if need, and the grayscale voltage by 23 inputs of described second input end is exported from described first output terminal 22, then the grid of described PMOS pipe 41 is added high voltage by switch-over control signal, grid to described PMOS pipe 42 adds low-voltage, grid to described NMOS pipe 43 adds high voltage, and the grid of described NMOS pipe 44 is added low-voltage.
One at present embodiment changes in the example, and described PMOS pipe 41 and/or PMOS pipe 42 can be changed to the NMOS pipe, and described NMOS pipe 43 and/or NMOS pipe 44 can be changed to the PMOS pipe.It will be appreciated by those skilled in the art that by grid to apply corresponding high voltage or low-voltage can make its conducting or disconnection, to realize described commutation circuit at above-mentioned metal-oxide-semiconductor.
Fig. 4 illustrates according to one of the first embodiment of the present invention and changes example, the structural representation of the described commutation circuit that source driver circuit of thin film transistor comprises. those skilled in the art understand, with embodiment illustrated in fig. 3 different be, single metal-oxide-semiconductor is changed to and utilizes PMOS pipe and NMOS to manage the cmos transmission gate of formation in parallel, can improve resistance characteristic like this. particularly, NMOS pipe 412 and PMOS pipe 411 also connect formation first cmos transmission gate, particularly, the source electrode of described NMOS pipe 412 and PMOS pipe 411 links together, drain electrode also links together, and respectively as the input end and the output terminal of described first cmos transmission gate, the grid of described NMOS pipe 412 and PMOS pipe 411 applies anti-phase control signal respectively. and those skilled in the art understand, because the symmetrical structure of metal-oxide-semiconductor, therefore the input end and the output terminal of described first cmos transmission gate can exchange. similar ground, NMOS pipe 422 and PMOS pipe 421 also connect formation second cmos transmission gate, NMOS pipe 432 and PMOS pipe 431 also connect formation the 3rd cmos transmission gate, NMOS pipe 442 and PMOS pipe 441 also connect formation the 4th cmos transmission gate. more specifically, to export from described first output terminal 22 by the grayscale voltage of described first input end 21 inputs if need, and the grayscale voltage by 23 inputs of described second input end is exported from described second output terminal 24, then described first cmos transmission gate is connected by switch-over control signal, second cmos transmission gate is disconnected, described the 3rd cmos transmission gate is disconnected, described the 4th cmos transmission gate is connected; To export from described second output terminal 24 by the grayscale voltage of described first input end 21 inputs if need, and the grayscale voltage by 23 inputs of described second input end is exported from described first output terminal 22, then described first cmos transmission gate is disconnected by switch-over control signal, second cmos transmission gate is connected, described the 3rd cmos transmission gate is connected, described the 4th cmos transmission gate is connected disconnection.
Those skilled in the art understand, two amplifiers only are shown among the embodiment shown in Figure 2, that is to say by described amplifier 31 and 32 grayscale voltage is outputed to the two-way source electrode line, therefore, in order to drive active matrix for example shown in Figure 5, can utilize m amplifier, the output terminal of above-mentioned these amplifiers is connected with source electrode line S1 to Sm respectively, wherein, m is an integer, and in other words, m is the columns of active driving array, for example, be that 1024 * 768 the corresponding m of display device is 1024*3 with resolution.
Fig. 2 the invention provides a kind of control method that is used for source driver circuit of thin film transistor to embodiment illustrated in fig. 4 and variation example according to the present invention.Preferably include the step that grayscale voltage is exported to amplifying circuit after by commutation circuit.
Those skilled in the art are in conjunction with described first embodiment and change example, can not repeat them here by described commutation circuit being placed described amplifying circuit before to realize present embodiment and to change example.
Fig. 2 is to embodiment illustrated in fig. 4 and variation example according to the present invention, and the present invention also provides a kind of thin film transistor liquid crystal display device, and particularly, it comprises the described source driver circuit of thin film transistor in described first embodiment and the variation example thereof.
Further, it will be appreciated by those skilled in the art that display device provided by the invention can be various types of thin film transistor liquid crystal display devices, and change according to concrete enforcement needs.In other words, all need reduce power consumption or the scheme that the thin film transistor liquid crystal display device of reaction velocity can adopt the foregoing description to provide is provided.Particularly, those skilled in the art can be in conjunction with prior art and above-mentioned enforcement, change example realizes such thin film transistor liquid crystal display device, does not repeat them here.
More than specific embodiments of the invention are described.It will be appreciated that the present invention is not limited to above-mentioned specific implementations, those skilled in the art can make various distortion or modification within the scope of the claims, and this does not influence flesh and blood of the present invention.
Claims (10)
1. source driver circuit of thin film transistor comprises:
-amplifying circuit, it is used for grayscale voltage is amplified; And
-commutation circuit, it is used for switching between the grayscale voltage to this passage grayscale voltage and adjacency channel,
It is characterized in that grayscale voltage exports described amplifying circuit to after by described commutation circuit.
2. source driver circuit of thin film transistor according to claim 1 is characterized in that, described amplifying circuit comprises first amplifier and second amplifier, and wherein, described first amplifier and described second amplifier are used for grayscale voltage is amplified output.
3. source driver circuit of thin film transistor according to claim 2 is characterized in that, described first amplifier and described second amplifier adopt the rail-to-rail amplifier.
4. according to claim 2 or 3 described source driver circuit of thin film transistor, it is characterized in that the in-phase end of described first amplifier connects first output terminal of described commutation circuit, end of oppisite phase connects its output terminal; The in-phase end of described second amplifier connects second output terminal of described commutation circuit, and end of oppisite phase connects its output terminal.
5. according to each described source driver circuit of thin film transistor in the claim 1 to 4, it is characterized in that, be connected in series the first transistor respectively between the first input end of described commutation circuit and first output terminal and second output terminal, be connected in series transistor seconds respectively between second input end of described commutation circuit and first output terminal and second output terminal.
6. source driver circuit of thin film transistor according to claim 5 is characterized in that, described the first transistor adopts the PMOS pipe, and described transistor seconds adopts the NMOS pipe.
7. source driver circuit of thin film transistor according to claim 5 is characterized in that, described the first transistor adopts cmos transmission gate, and described transistor seconds adopts cmos transmission gate.
8. according to each described source driver circuit of thin film transistor in the claim 1 to 7, it is characterized in that, first output terminal of described commutation circuit is connected to the in-phase end of described first amplifier, and second output terminal of described commutation circuit is connected to the in-phase end of described second amplifier.
9. a control method that is used for source driver circuit of thin film transistor is characterized in that, comprises step: export grayscale voltage to amplifying circuit after by commutation circuit.
10. a thin film transistor liquid crystal display device is characterized in that, comprises according to each described TFT source electrode drive circuit in the aforesaid right requirement 1 to 8.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910051942A CN101707048A (en) | 2009-05-25 | 2009-05-25 | Source driver circuit of thin film transistor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN200910051942A CN101707048A (en) | 2009-05-25 | 2009-05-25 | Source driver circuit of thin film transistor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104616632A (en) * | 2015-02-16 | 2015-05-13 | 彩优微电子(昆山)有限公司 | Liquid crystal display driving circuit capable of preventing de-energization shadow and driving method thereof |
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2009
- 2009-05-25 CN CN200910051942A patent/CN101707048A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104616632A (en) * | 2015-02-16 | 2015-05-13 | 彩优微电子(昆山)有限公司 | Liquid crystal display driving circuit capable of preventing de-energization shadow and driving method thereof |
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Application publication date: 20100512 |