CN102376275A - TFT-LCD (thin film transistor-liquid crystal display) driving circuit and liquid crystal display device - Google Patents
TFT-LCD (thin film transistor-liquid crystal display) driving circuit and liquid crystal display device Download PDFInfo
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Abstract
The embodiment of the invention discloses a TFT-LCD (thin film transistor-liquid crystal display) driving circuit and a liquid crystal display device, relating to the technical field of liquid crystal display and used for reducing the number of source drivers and reducing the manufacturing cost of a TFT-LCD under the condition of not affecting the normal charge of a pixel electrode. The TFT-LCD driving circuit comprises the source driver, and each output end of the source driver is connected with at least two data wires; furthermore, transfer switches of which the number corresponds to that of the data wires are arranged between the output ends of the source driver and the data wires, and the transfer switches are used for controlling the data transmission from the source driver to the data wires, wherein a sampling and holding unit is arranged between the transfer switches and the data wires, and the sampling and holding unit is used for saving display data which is provided from the source driver to the data wires. The scheme provided in the embodiment of the invention is applicable to any thin-film transistor liquid crystal display equipment.
Description
Technical field
The present invention relates to technical field of liquid crystal display, relate in particular to a kind of TFT-LCD driving circuit and have the liquid crystal indicator of this driving circuit.
Background technology
In traditional T FT-LCD (Thin Film Transistor-Liquid Crystal Display, Thin Film Transistor-LCD), every data line (data line) all is connected with the output line of a source electrode driver (Source Driver); Like this, in a LCD, just the source electrode driver of needs and data line equal amount causes the cost of source drive unit higher.
In order to reduce the use of source electrode driver, reduce the cost of manufacture of TFT-LCD, there is following improvement project in the prior art:
Between source electrode driver and data line, change-over switch is set; The output line of a source electrode driver is connected with many data lines through said change-over switch simultaneously, i.e. control through said change-over switch makes same source electrode driver timesharing ground for many data lines video data is provided.Simultaneously; In order to make the video data that writes down in the pixel electrode after the change-over switch on the data line is broken off, can continue to keep stable, therefore in this improvement project, also added the data write time of to control respectively said many data lines with many grid lines of said many data line equivalent.When the change-over switch on data line is broken off therein, can adjust in time signal on the corresponding grid line corresponding TFT gate turn-off to guarantee the accuracy of recorded data in the pixel electrode.
State in realization in the process of improvement project of TFT-LCD, the inventor finds to have following problem in the prior art at least: in above-mentioned improvement project, though reduced the quantity of source electrode driver, can reduce the cost of manufacture of TFT-LCD; But, through acquiring the on off state that grid line controls respectively the corresponding pixel of said many data lines, can make the corresponding minimizing of duration of charging of the pixel electrode that said many data lines are corresponding, the grid line of setting up simultaneously can have influence on the aperture opening ratio of TFT-LCD.
Summary of the invention
Embodiments of the invention provide a kind of TFT-LCD driving circuit and liquid crystal indicator, in order to not influence the quantity that reduces source electrode driver under the situation that pixel electrode charges normal, reduce the cost of manufacture of TFT-LCD.
For achieving the above object, embodiments of the invention adopt following technical scheme:
A kind of TFT-LCD driving circuit; Comprise source electrode driver; Each output terminal of this source electrode driver links to each other and is connected at least two data lines; And between the output terminal of said source electrode driver and said data line, be provided with and the corresponding change-over switch of said data line equivalent, the data that this change-over switch is used to control from said source electrode driver to said data line transmit; Wherein, between said change-over switch and said data line, be provided with sample holding unit, said sample holding unit is used to preserve the video data that said source electrode driver offers said data line.
A kind of liquid crystal indicator has above-mentioned TFT-LCD driving circuit in this liquid crystal indicator.
TFT-LCD driving circuit and liquid crystal indicator that the embodiment of the invention provides, an output terminal through a source electrode driver is that many data lines provide video data, can reduce the usage quantity of source electrode driver, thereby reduces the cost of manufacture of TFT-LCD; And; Preserve the video data that source electrode driver offers data line through the sample holding unit that between change-over switch and data line, is provided with; Can be after breaking off with the corresponding change-over switch of said data line; Make said sample holding unit still keep higher voltage, so just can guarantee the duration of charging of pixel electrode, and can not have influence on the video data that has write down in the pixel electrode.Compared with prior art; The TFT-LCD driving circuit and the liquid crystal indicator that provide in the embodiment of the invention; The quantity that reduces source electrode driver under the situation that pixel electrode charges normal can not influenced; Reduce the cost of manufacture of TFT-LCD, the aperture opening ratio to TFT-LCD does not have harmful effect yet simultaneously.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art; The accompanying drawing of required use is done to introduce simply in will describing embodiment below; Obviously, the accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the electrical block diagram of the TFT-LCD driving circuit in the embodiment of the invention;
Fig. 2 is the electrical block diagram of the TFT-LCD driving circuit in the embodiment of the invention one;
Fig. 3 is the implementation one of the sample holding unit among Fig. 2;
Fig. 4 is the implementation two of the sample holding unit among Fig. 2;
Fig. 5 is the electrical block diagram of the TFT-LCD driving circuit in the embodiment of the invention two;
Fig. 6 is the electrical block diagram of the Gamma voltage regulator circuit in the embodiment of the invention four;
Fig. 7 is the another kind of implementation synoptic diagram of TFT-LCD driving circuit in the embodiment of the invention;
Fig. 8 is the synoptic diagram of the Digital Implementation of the Gamma voltage regulator circuit in four in the embodiment of the invention;
Reference numeral: the output terminal of 101-source electrode driver; The 102-data line; The 103-change-over switch; The 104-sample holding unit; The 141-operational amplifier; 142,143-electric capacity; 105-data write switch; The 601-first resistance regulating circuit; The 602-second resistance regulating circuit.
Embodiment
To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
Below in conjunction with accompanying drawing TFT-LCD driving circuit and the liquid crystal indicator that provides in the embodiment of the invention is described in detail.
As shown in Figure 1; The TFT-LCD driving circuit that provides in the embodiment of the invention; Comprise source electrode driver; The output terminal 101 of this source electrode driver is connected with at least two data lines 102, and between the output terminal 101 of said source electrode driver and said data line 102, is provided with and the corresponding change-over switch 103 of said data line 102 equivalent, and this change-over switch 103 is used to control from said source electrode driver to data line 102 data and transmits; Wherein, between said change-over switch 103 and said data line 102, be provided with sample holding unit 104, said sample holding unit 104 is used to preserve the video data that said source electrode driver offers said data line 102.
In the situation that an output terminal of the source electrode driver shown in Fig. 1 101 connects 4 data lines 102 is a kind of situation in the scheme protected of the present invention.Wherein, SW1, SW2, SW3, SW4 are respectively the control ends of the corresponding change-over switch of 4 data lines; Through control end SW1, SW2, SW3, when 4 change-over switches of SW4 control are opened successively by turns; Source electrode driver is exported the signal that corresponding video data is given data line 102 respectively through output terminal 101, and the video data that the while source electrode driver is exported through output terminal 101 also can be stored in the sample holding unit 104.Like this; After the corresponding change-over switch of data line is broken off therein; Output terminal at sample holding unit 104; Just the input end of this data line still keeps high-tension state, the influence of caused change in voltage when making the data that write in the pixel electrode can not receive change-over switch to break off, and then guarantee to be written to the accuracy of the data in the pixel electrode.
In fact, in the present embodiment, the quantity of said data line 102 can be more than or equal to 2, but the quantity that it is noted that said data line 102 simultaneously is not can infinite expanding.Because; The time that every capable pixel is opened, the chances are 16.6 μ s; And in the prior art the required duration of charging of each sub-pix can be controlled at less than 4 μ s; Therefore when certain delegation's pixel is opened, can open 4～5 data lines through control its switch 103 in order and write video data through same output terminal for the corresponding sub-pix of these 4～5 data lines provides by source electrode driver.Along with the development of liquid crystal drive technology or the improvement of technology; The required duration of charging of each sub-pix may reduce gradually; Like this; Just can utilize a source electrode driver to drive the more data line also for the more data line provides video data, the cost when being reduced in the driving circuit of making among the TFT-LCD greatly.
Preferably, can utilize the same output of a source electrode driver to bring in is that 3 data lines provide video data, and these 3 data lines are distinguished the three kinds of sub-pixs of red, green, blue (RGB) in the corresponding same row pixel; Like this, just can directly adjust some parameter on the said data line, such as gamma voltage in the source electrode driver part.
Above-mentioned TFT-LCD driving circuit; Same output terminal through a source electrode driver is that many data lines provide video data; Can make same source electrode driver video data is provided, and then reduce the usage quantity of source electrode driver, reduce the cost of manufacture of TFT-LCD for the more data line; And; Preserve the video data that source electrode driver offers data line through the sample holding unit that between change-over switch and data line, is provided with; Can be after breaking off with the corresponding change-over switch of said data line; Make said sample holding unit still keep higher voltage, so just can guarantee the duration of charging of pixel electrode, and can not have influence on the video data that has write down in the pixel electrode.Simultaneously, utilize the TFT-LCD driving circuit that provides in the present embodiment, can not produce harmful effect the aperture opening ratio of TFT-LCD.
The situation that below main same output terminal with a source electrode driver is connected three kinds of sub-pixs of red, green, blue of 3 data lines and these 3 corresponding respectively same row pixels of data line is an example, and the TFT-LCD driving circuit that combines instantiation to come the embodiment of the invention is provided is done detailed description further.
Wherein, in following examples, said change-over switch is selected metal oxide semiconductor field effect tube (MOS-FET is called for short metal-oxide-semiconductor) for use; The source electrode of this MOS and drain electrode are serially connected between the output terminal 101 and sample holding unit 104 of source electrode driver, and its grid connects change-over switch control end (such as SW1, SW2 or SW3).
Embodiment one:
TFT-LCD driving circuit as shown in Figure 2 is identical with TFT-LCD driving circuit ultimate principle described in Fig. 1; But, in the scheme of Fig. 2, the output terminal 101 (Sm) of source electrode driver connects 3 data lines 102 simultaneously, and three kinds of sub-pixs of red, green, blue of the corresponding same row pixel of these 3 data lines, 102 difference.Between the output terminal 101 of said source electrode driver and data line 102, also be serially connected with change-over switch 103 and sample holding unit 104.
The same output terminal of a source electrode driver is connected with 3 change-over switches simultaneously, and then is connected with 3 sample holding units, 3 data lines; That is to say, can make that an output line of source electrode driver can be to timesharing the signal that 3 row sub-pixs provide video data through the control of said 3 change-over switches.Correspondingly, provide the quantity of the sub-pix of data-signal can reach in the past 3 times by same source electrode driver; Like this, comparing with generalized case just only needs the source electrode driver of original 1/3 quantity just passable, has significantly reduced the use amount of source electrode driver, can reduce the cost of manufacture of TFT-LCD.
In the present embodiment, the voltage that provides through control SW1, SW2, SW3 can be controlled the data-signal input of three kinds of sub-pixs of red, green, blue in the same row pixel.Particularly; Voltage through control SW1, SW2, SW3 provide can be opened the corresponding change-over switch of three kinds of sub-pixs of red, green, blue successively, by turns, has only the change-over switch that connects on the data lines to be in open mode in the promptly same at one time row pixel.
Illustrate; Situation as shown in Figure 2; When the corresponding grid line of certain delegation pixel is in high level state, at first, be that the corresponding change-over switch of red sub-pixel provides a high level, said change-over switch is opened through SW1; This moment, the output terminal Sm of source electrode driver provided video data for the red sub-pixel corresponding data line, and in the red sub-pixel of same row, write video data; Simultaneously, said video data also is stored in the sample holding unit., SW1 converts SW2 into high level simultaneously when converting low level into; The corresponding change-over switch of red sub-pixel this moment is broken off; The corresponding change-over switch of green sub-pix is opened; The output terminal Sm of source electrode driver begins to green sub-pix corresponding data line provides video data, and in the green sub-pix of same row, writes video data.At this moment, because the corresponding sample holding unit of red sub-pixel still is in high level state, so the charged state of red sub-pixel can't be affected because of the disconnection of change-over switch.
Afterwards, the pixel charging process after the change-over switch that green sub-pix is corresponding is broken off, the change-over switch of blue sub-pix correspondence is opened, similar with said process, repeat no more.
Like this, the duration of charging of three kinds of sub-pixs of red, green, blue is just different; But, enough fast as long as each sub-pix is full of the time of electricity, do not influence display effect.For example, the TFT-LCD of present embodiment adopts 1280*1024 pixel, and the frame refresh rate of 60Hz carries out picture and shows that the time that every capable pixel is opened is about 16.6 μ s, and the duration of charging of three kinds of sub-pixs of RGB can reach 16,12,8 μ s respectively; And the actual required duration of charging of each sub-pix is no more than 4 μ s, so in such scheme, the duration of charging that provides respectively for three kinds of sub-pixs of RGB is enough to accomplish its charging process, can guarantee charging effect, and then also can not produce harmful effect to display effect.
Further, in the present embodiment, said sample holding unit 104 can have following two kinds of implementations:
One of which, as shown in Figure 3, said sample holding unit 104 comprises: an operational amplifier 141 and an electric capacity 142;
The input end in the same way (+) of said operational amplifier 141 connects said change-over switch 103, and its reverse input end (-) is connected said data line 102 simultaneously with output terminal;
One end of said electric capacity 142 connects the reference voltage V com of said TFT-LCD, and the other end is connected in the same way between the input end of said change-over switch 103 and said operational amplifier 141.
When source electrode driver provides video data through output terminal 101 for data line 102, when said display data signal is passed through sample holding unit 104, can electric capacity 142 be charged; Then, make the input end in the same way of operational amplifier 141 remain on the state of a high level through this electric capacity 142.Because the input end in the same way of operational amplifier and the level between the reverse input end are consistent, so the reverse input end of operational amplifier 141 and output terminal remain on the state of a high level too again.Like this, though change-over switch break off, but the video data of source electrode driver output has been stored in the sample holding unit 104.When source electrode driver provided video data for the next line pixel, the data that are kept in the sample holding unit 104 just can change.
Because the internal resistance of operational amplifier itself is quite big, external voltage changes little to the influence of its output end voltage, has the function of keeping voltage preferably; Therefore, the electric capacity to electric capacity 142 does not have special demands in the present embodiment, and it can be the electric capacity that electric capacity is less.
Its two, as shown in Figure 4, said sample holding unit 104 comprises an electric capacity 143, an end ground connection of this electric capacity 143, the other end is connected between said change-over switch 103 and the said data line 102.
When the output terminal 101 through source electrode driver provides video data for data line 102, when said display data signal is passed through sample holding unit 104, can electric capacity 143 be charged; Then, can make the input end of data line 102 remain on the state of a high level through this electric capacity 143.Even change-over switch 103 has been broken off, but the video data of source electrode driver output has been stored in the sample holding unit 104.When source electrode driver provided video data for the next line pixel, the data that are kept in the sample holding unit 104 just can change.
Owing to only adopt an electric capacity to keep the level of data line input end, therefore, need to select the bigger electric capacity of electric capacity here; Preferably, the electric capacity of this electric capacity is more than 100 times of pixel capacitance, can select for use the electric capacity of electric capacity between 10pF to 1nF as the electric capacity in the sampling hold circuit 104 143 usually.
In the present embodiment; Be that to connect 3 data lines be example for same output terminal with a source electrode driver; But the implementation of above-mentioned sample holding unit is applicable to this a kind of situation incessantly, and the same output terminal that can also be applicable to a source electrode driver certainly connects the situation of 2 or 4 even more data lines.
The TFT-LCD driving circuit that utilizes the embodiment of the invention to provide, the same output terminal through a source electrode driver is that many data lines provide video data, can reduce the usage quantity of source electrode driver, thereby reduces the cost of manufacture of TFT-LCD; And; Preserve the video data that source electrode driver offers data line through the sample holding unit that between change-over switch and data line, is provided with; Can be after breaking off with the corresponding change-over switch of said data line; Make said sample holding unit still keep higher voltage, so just can guarantee the duration of charging of pixel electrode, and can not have influence on the video data that has write down in the pixel electrode.
Embodiment two:
In the present embodiment, TFT-LCD driving circuit shown in Figure 2 is done further improvement.Specifically as shown in Figure 5.
The TFT-LCD driving circuit that is provided in the present embodiment on the basis of TFT-LCD driving circuit shown in Figure 2, is set up a data write switch 105 again; This data write switch 105 is located between said sample holding unit 104 and the said data line 102.
Said data write switch 105 can be a metal-oxide-semiconductor; Its grid connects control end SW, and the signal of this control end SW can be provided by the time schedule controller of said TFT-LCD and amplify through the TFT-LCD driving circuit, and its source electrode is connected said sample holding unit 104 and said data line 102 respectively with drain electrode.
Like this; When control end SW1 and SW2 control its corresponding change-over switch respectively and open successively; Control end SW is being in low level always; Data write switch 105 is in off-state, and current needs carry out the corresponding grid line of pixel column that data write and also are in off-state, need send video data red, green sub-pix this moment to and only be stored in the sample holding unit 104 and can not be written in the pixel electrode.When its corresponding change-over switch of control end SW3 control was opened, the level of regulating control end SW was simultaneously opened data write switch 105, and the correspondingly current corresponding grid line of one-row pixels that needs the completion data to write is also opened; At this moment, the video data of having preserved in the sample holding unit 104 that three kinds of sub-pixs of red, green, blue are corresponding will be written in the pixel electrode of current this delegation's pixel.
Utilize the TFT-LCD driving circuit in the present embodiment; Not only the quantity that reduces source electrode driver under the situation that pixel electrode charges normal can not influenced; Reduce the cost of manufacture of TFT-LCD; But also can control duration of charging of each sub-pix better, can avoid occurring the too short problem of duration of charging of a certain row sub-pix.
Embodiment three:
The principle of the TFT-LCD driving circuit among TFT-LCD driving circuit that provides in the present embodiment and embodiment one, the embodiment two is basic identical.
But, in the present embodiment, said TFT-LCD driving circuit also comprises the time schedule controller (not shown) that is used to control said change-over switch 103; Be that said time schedule controller links to each other with the control end (SW1, SW2, SW3) of said change-over switch 103 through an amplifying circuit.
In the present embodiment, time schedule controller is that the pulse height that provides of SW1, SW2, SW3 is incomplete same; That is to say that said time schedule controller is that the initial cut-in voltage that provides of the corresponding change-over switch of three kinds of sub-pixs of red, green, blue is incomplete same, it is also incomplete same after amplification, to output to the last cut-in voltage of SW1, SW2, SW3 then.
In conjunction with Fig. 2 or shown in Figure 5, different through the cut-in voltage that SW1, SW2, SW3 are carried on each change-over switch (metal-oxide-semiconductor), the voltage that adds on the grid of the metal-oxide-semiconductor that just three kinds of sub-pixs of red, green, blue are corresponding is different.Can produce the influence of two aspects like this: one, after said change-over switch is connected; Because the channel resistance when metal-oxide-semiconductor is opened is relevant with its grid voltage; Therefore different grid voltages will produce different channel resistances; This channel resistance is connected with the resistance on the data line and is caused different charging loads and delay, and then influences the pixel duration of charging.Two, after said change-over switch was broken off, because the electric charge of stray capacitance will be redistributed, the voltage on the data line can occur one and jump voltage down, and following size of jumping voltage is directly proportional with the cut-in voltage of grid and the difference between the shutoff voltage; So different cut-in voltages can produce different following jumping voltage, the actual voltage that is loaded on the pixel electrode of result also has different following jumpings, and charging voltage is produced certain influence.
Can know by above-mentioned analysis; The size of the cut-in voltage of adjustment metal-oxide-semiconductor; Can have influence on the variation of the inner channel resistance of metal-oxide-semiconductor and the variation of the following jumping voltage on the data line; And then can utilize actual duration of charging and the charging voltage of the control of the cut-in voltage of metal-oxide-semiconductor being adjusted the different colours pixel that connects on each data line, also just be equivalent to RGB Gamma voltage is made adjusting.
In simulation process; Setting is respectively 40V, 35V, 30V through the amplitude of the unbalanced pulse that SW1, SW2, SW3 provide; When shutoff voltage was 0.1V, the following jumping voltage that then occurs on the red, green, blue sub-pix corresponding data line was respectively 0.311V, 0.235V, 0.158V; And then the actual charging voltage of pixel electrode also can reduce 0.311V, 0.235V, 0.158V respectively.
In the present embodiment; Through applying the amplitude that different cut-in voltages changes the downward modulation voltage that is occurred on channel resistance and the data line of said change-over switch for the change-over switch that is connected on the different pieces of information line in the TFT-LCD driving circuit, and then adjust the duration of charging and the actual charging voltage of the different colours pixel that connects on the said data line; Reach the effect of regulating RGB Gamma curve to a certain extent respectively.
If RGB Gamma voltage is fully independently regulated, then can realize through when different change-over switches is opened, being equipped with different Gamma reference voltages.Specifically referring to embodiment four.
Embodiment four:
The principle of the TFT-LCD driving circuit among TFT-LCD driving circuit that provides in the present embodiment and embodiment one, the embodiment two is basic identical.
But, in the present embodiment, said TFT-LCD driving circuit also comprises the Gamma voltage regulator circuit, and the output terminal of this Gamma voltage regulator circuit connects said source electrode driver; And, comprise three control ends in this Gamma voltage regulator circuit, and said three control ends are respectively applied for the Gamma reference voltage output of regulating three kinds of sub-pixs of red, green, blue.
As shown in Figure 6, said Gamma voltage regulator circuit comprises: be serially connected at least two divider resistances between voltage input end AVdd and the earth terminal, the extension line between per two divider resistances is connected to said source electrode driver as output terminal; One end of at least two divider resistances of said serial connection is connected to said voltage input end AVdd through the first resistance regulating circuit 601, and the other end of at least two divider resistances of said serial connection is connected to said earth terminal through the second resistance regulating circuit 602;
The said first resistance regulating circuit 601 comprises first resistance R 11, second resistance R 21 and the 3rd resistance R 31 of parallel connection, and said first resistance R 11, second resistance R 21, the 3rd resistance R 31 are connected in series a switch again respectively;
The said second resistance regulating circuit 602 comprise the 4th resistance R 11 of parallel connection ', the 5th resistance R 21 ' and the 6th resistance R 31 ', said the 4th resistance R 11 ', the 5th resistance R 21 ', a switch of the 6th resistance R 31 ' be connected in series respectively.
Switch in the above-mentioned first resistance regulating circuit 601 and the second resistance regulating circuit 602 can be a metal-oxide-semiconductor, and the grid of this metal-oxide-semiconductor is connected with outside control end; Particularly,
Said first resistance R, 11 corresponding switch and said the 4th resistance R 11 ' corresponding switch are connected to the first control end SW1; Said second resistance R, 21 corresponding switch and said the 5th resistance R 21 ' corresponding switch are connected to the second control end SW2; Said the 3rd resistance R 31 corresponding switch and said the 6th resistance R 31 ' corresponding switch are connected to the 3rd control end SW3.
Said control end SW1, SW2, SW3 export high level signal successively, the output of the Gamma reference voltage of three kinds of sub-pixs of control red, green, blue:
When through SW1 output high level, the switch that R11 is connected with R11 ' all can be opened, and R11, R11 ' and middle resistance string constitute the Gamma reference voltage feed circuit of red sub-pixel at this moment;
When through SW2 output high level, the switch that R21 is connected with R21 ' all can be opened, and R21, R21 ' and middle resistance string constitute the Gamma reference voltage feed circuit of green sub-pix at this moment;
When through SW3 output high level, the switch that R31 is connected with R31 ' all can be opened, and R31, R31 ' and middle resistance string constitute the Gamma reference voltage feed circuit of blue sub-pix at this moment.
Above-mentioned Gamma voltage regulator circuit is mainly controlled the Gamma curve of RGB through the dynamic range of regulating Gamma voltage.
In the present embodiment, control end SW1, SW2, the SW3 of control end SW1, SW2, change-over switch that three kinds of sub-pixs of SW3 and red, green, blue are corresponding respectively are the same.Gamma reference voltage that like this, can guarantee to provide and pixel charging in time synchronously.
In the Gamma of present embodiment voltage regulator circuit, also remain with wire jumper Jump interface, so that when three kinds of sub-pixs of red, green, blue adopt identical Gamma voltage, can directly be communicated with wire jumper.As shown in Figure 6, between said first resistance regulating circuit 601 and said voltage input end AVdd, be provided with wire jumper interface Jump3, between said second resistance regulating circuit 602 and said earth terminal, be provided with wire jumper interface Jump4; Simultaneously,
Between at least two divider resistances of said voltage input end AVdd and said serial connection, also be serially connected with the first common resistance R1 and a wire jumper interface Jump1, between at least two divider resistances of said serial connection and said earth terminal, also be serially connected with the second common resistance R1 ' and a wire jumper interface Jump2.
Particularly, in the time need controlling respectively, Jump1 and Jump2 place are broken off, simultaneously Jump3 is connected through wire jumper with the Jump4 place the corresponding Gamma voltage of three kinds of sub-pixs of red, green, blue; When three kinds of sub-pixs of red, green, blue being adopted identical Gamma voltage; Can Jump1 be connected through wire jumper with the Jump2 place; And Jump3 and Jump4 place are broken off; Jump1 is communicated with AVdd and R1 like this, and Jump2 is communicated with R1 ' and ground, and SW1, SW2, SW3 and R11, R21, R31, R11 ', R21 ', R31 ' are no longer worked.
In the present embodiment, through the output that the Gamma voltage regulator circuit dynamically adjusts the Gamma reference voltage is set in the TFT-LCD driving circuit, the Gamma magnitude of voltage that provides it to need respectively for the sub-pix of different colours.Utilize the scheme in the present embodiment; Can realize when source electrode driver timesharing ground provides shows signal for the red, green, blue sub-pix, be that the sub-pix of different colours provides different Gamma reference voltages thereby come to regulate respectively RGBGamma voltage through above-mentioned Gamma voltage regulator circuit in the different periods.
Certainly, also can adopt and use independently three groups of Gamma divider resistances and switching switch circuit to realize this function respectively, but circuit cost is higher.
In addition, can also realize above-mentioned functions through adopting digital Gamma circuit.As shown in Figure 8, select a kind of of three kinds of outputs of digital Gamma circuit through control end SW1, SW2, SW3 on Digital Gamma IC (digital gamma circuit) chip, for a kind of in three kinds of sub-pixs of red, green, blue provides Gamma reference voltage.
In the above-described embodiments, all less than consider with at least two data lines that the same output terminal of a source electrode driver links to each other between the position concern; But, because most cases is to utilize the same output terminal of a source electrode driver that three kinds of sub-pixs of the red, green, blue in the same row pixel are controlled, therefore giving tacit consent to said at least two data lines is adjacent settings.
But it should be noted that the scheme that provides in the embodiment of the invention has more than adjacent this a kind of scene that is provided with of at least two data lines that is applicable to that said and same source electrode driver output terminal links to each other; At least two data lines that said and same source electrode driver output terminal links to each other can certainly be to be provided with at interval.
Connecting two data lines simultaneously with the same output terminal of a source electrode driver is example; As shown in Figure 7; Two data line branches that same source electrode driver output terminal is connected simultaneously be located at LCD about in two zones; The signal transmission direction of this source electrode driver output video data is controlled through the change-over switch that links to each other respectively on said two data lines, and change-over switch is to control through control end SW1 and SW2.
Illustrate, in the present embodiment, the viewing area adopts 1280*1024 pixel to show; When SW1 output high level, during the SW2 output low level, a certain output terminal of source electrode driver and the left-half of viewing area are connected, and the video data of output left-half; When SW2 output high level, during the SW1 output low level, the said same output terminal of source electrode driver and the right half part of viewing area are connected, and the video data of output right half part.
In the present embodiment, any change need not take place in the existing single channel way of output in the time schedule controller.Is example in conjunction with situation shown in Figure 7 and with the viewing area for the 1280*1024 pixel; Time schedule controller can territory, first output display area left-half the corresponding video data of 640 row pixels; Export the corresponding video data of 640 row pixels of right half part afterwards again, therefore its single channel way of output is had no impact.
Yet, utilize circuit structure shown in Figure 7, two data lines far away at interval are connected to the same output terminal of source electrode driver, just need be on technology realize the dispensing of signal through the via hole cross-line; Because the circuit on the TFT-LCD array base palte is originally with regard to more complicated, therefore circuit structure shown in Figure 7 implements difficulty more greatly.
A kind of liquid crystal indicator also is provided in the embodiment of the invention, and this liquid crystal indicator has the TFT-LCD driving circuit described in the foregoing description.
The liquid crystal indicator that provides in the embodiment of the invention, the same output terminal through a source electrode driver is that many data lines provide video data, can reduce the usage quantity of source electrode driver, thereby reduces the cost of manufacture of TFT-LCD; And; Preserve the video data that source electrode driver offers data line through the sample holding unit that between change-over switch and data line, is provided with; Can be after breaking off with the corresponding change-over switch of said data line; Make said sample holding unit still keep higher voltage, so just can guarantee the duration of charging of pixel electrode, and can not have influence on the video data that has write down in the pixel electrode.
In the scheme that the embodiment of the invention provides; Parts such as the sample holding unit of setting up can be when making array base palte; Make with devices such as TFT through composition technology, therefore can't increase the realization difficulty of technology, nor can improve the cost of manufacture of TFT-LCD.
The scheme that the embodiment of the invention provides goes in any liquid crystal display.
The above; Be merely embodiment of the present invention, but protection scope of the present invention is not limited thereto, any technician who is familiar with the present technique field is in the technical scope that the present invention discloses; The variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.
Claims (12)
1. TFT-LCD driving circuit; Comprise source electrode driver; Each output terminal of this source electrode driver is connected with at least two data lines; And between the output terminal of said source electrode driver and said data line, be provided with and the corresponding change-over switch of said data line equivalent, the data that this change-over switch is used to control from said source electrode driver to said data line transmit; It is characterized in that between said change-over switch and said data line, be provided with sample holding unit, said sample holding unit is used to preserve the video data that said source electrode driver offers said data line.
2. TFT-LCD driving circuit according to claim 1 is characterized in that, said sample holding unit comprises: an operational amplifier and an electric capacity;
The input end in the same way of said operational amplifier connects said change-over switch, and its reverse input end is connected said data line simultaneously with output terminal;
One end of said electric capacity connects the reference voltage V com of said TFT-LCD, and the other end is connected in the same way between the input end of said change-over switch and said operational amplifier.
3. TFT-LCD driving circuit according to claim 1 is characterized in that, said sample holding unit comprises an electric capacity, an end ground connection of this electric capacity, and the other end is connected between said change-over switch and the said data line; And the electric capacity of said electric capacity is more than 100 times of pixel capacitance.
4. according to claim 1,2 or 3 described TFT-LCD driving circuits, it is characterized in that the quantity of at least two data lines that are connected with the same output terminal of source electrode driver is 3; And said 3 data lines are three kinds of sub-pixs of corresponding red, green, blue respectively.
5. TFT-LCD driving circuit according to claim 4 is characterized in that, this TFT-LCD driving circuit is that the cut-in voltage that provides of the corresponding respectively change-over switch of said at least two data lines is incomplete same.
6. TFT-LCD driving circuit according to claim 4 is characterized in that, also comprises the Gamma voltage regulator circuit in the said TFT-LCD driving circuit, and the output terminal of this Gamma voltage regulator circuit connects said source electrode driver;
Comprise three control ends in the said Gamma voltage regulator circuit, and said three control ends are respectively applied for the Gamma reference voltage output of regulating three kinds of sub-pixs of red, green, blue.
7. TFT-LCD driving circuit according to claim 6 is characterized in that, said Gamma voltage regulator circuit comprises: be serially connected at least two divider resistances between voltage input end and the earth terminal; One end of at least two divider resistances of said serial connection is connected to said voltage input end through the first resistance regulating circuit, and the other end of at least two divider resistances of said serial connection is connected to said earth terminal through the second resistance regulating circuit;
The said first resistance regulating circuit comprises first resistance, second resistance and the 3rd resistance of parallel connection, and said first resistance, second resistance, the 3rd resistance are connected in series a switch respectively;
The said second resistance regulating circuit comprises the 4th resistance, the 5th resistance and the 6th resistance of parallel connection, and said the 4th resistance, the 5th resistance, the 6th resistance are connected in series a switch respectively; And,
Said first resistance corresponding switch and said the 4th resistance corresponding switch are connected to first control end; Said second resistance corresponding switch and said the 5th resistance corresponding switch are connected to second control end; Said the 3rd resistance corresponding switch and said the 6th resistance corresponding switch are connected to the 3rd control end.
8. TFT-LCD driving circuit according to claim 7 is characterized in that, between said first resistance regulating circuit and said voltage input end, is provided with the wire jumper interface, between said second resistance regulating circuit and said earth terminal, is provided with the wire jumper interface; Simultaneously,
Between at least two divider resistances of said voltage input end and said serial connection, be serially connected with first common resistance and a wire jumper interface, between at least two divider resistances of said serial connection and said earth terminal, be serially connected with second common resistance and a wire jumper interface.
9. according to claim 1,2 or 3 described TFT-LCD driving circuits, it is characterized in that, between said sample holding unit and said data line, also be provided with the data write switch.
10. TFT-LCD driving circuit according to claim 9 is characterized in that, said data write switch is the metal oxide semiconductor field effect tube metal-oxide-semiconductor;
The grid of said metal-oxide-semiconductor connects the time schedule controller of said TFT-LCD, and its source electrode is connected said sample holding unit and said data line respectively with drain electrode.
11., it is characterized in that the adjacent setting of at least two data lines that is connected with the same output terminal of said source electrode driver according to claim 1,2 or 3 described TFT-LCD driving circuits; Perhaps, at least two data lines that are connected with the same output terminal of said source electrode driver are provided with at interval.
12. a liquid crystal indicator is characterized in that, has each described TFT-LCD driving circuit in the claim 1 to 11 in this liquid crystal indicator.
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