KR20120124368A - Driving device, driving method of gamma amplifier and liquid crystal display - Google Patents

Abstract

PURPOSE: A driving device, a driving method of a gamma amplifier and a liquid crystal display device are provided to solve the problem due to the difference between off-set voltages of the gamma amplifier by using an auto zero circuit. CONSTITUTION: A gamma amplifier device(310) receives a gradation voltage. The gamma amplifier device outputs an output voltage which is differentially amplifying the gradation voltage. A gamma string unit is composed of a plurality of resistors and generates an analog voltage by receiving the output voltage of the gamma amplifier device. A digital to analog converter converts the output voltage corresponding to an input bit into an analog form. A buffer amplifier differentially amplifies the output voltage of the digital to analog converter. [Reference numerals] (200) Gate driver; (300) Data driver; (310) Gamma amplification device; (400) Grayscale voltage generator; (500) Signal controller

Description

DRIVING DEVICE, DRIVING METHOD OF GAMMA AMPLIFIER AND LIQUID CRYSTAL DISPLAY}

The present invention relates to a driving apparatus, a method of driving a gamma amplifier, and a liquid crystal display.

In order to reduce costs in a panel of a liquid crystal display (LCD) using a thin film transistor (TFT), wiring is reduced and a gamma amplifier is called a source driving integrated circuit. It is embedded inside the data driver which is a driver integrated circuit. Such an attempt causes offsets of gamma amplifiers in a panel of a liquid crystal display using a plurality of data drivers, thereby rapidly lowering yield or difficulty in implementing the data drivers. That is, due to the difference between the offset voltages of the gamma amplifier, display defects such as dimming of the screen may occur.

In order to solve this problem, a conventional swapping or chopping structure may be used. However, since this method compensates for the offset voltage, it is difficult to remove the absolute value of the offset voltage and is a frequency characteristic between the swapping frequency of the data driver and the swapping frequency of the gamma amplifier. Therefore, the screen may flicker due to the frequency of the harmonic component or the frequency of the mutual interference.

SUMMARY OF THE INVENTION An object of the present invention is to provide a driving device, a method of driving a gamma amplifier, and a liquid crystal display device, which solves a problem caused by a difference between offset voltages of a gamma amplifier embedded in a data driver using an auto zero circuit. will be.

Another object of the present invention is to provide a driving device, a method of driving a gamma amplifier, and a liquid crystal display, which solve a problem of picking due to feed through.

According to one embodiment of the invention, a drive device is provided. The drive device, A gamma amplifier configured to receive a gray voltage and output an output voltage obtained by differentially amplifying the gray voltage; A gamma string unit including a plurality of resistors receiving the output voltage from the gamma amplifier to generate an analog voltage; A digital-to-analog converter that selects an output voltage corresponding to an input bit from the output voltage output by the gamma string unit and converts the output voltage into an analog form; And a buffer amplifier for differentially amplifying the output voltage output from the digital-to-analog converter and outputting the output voltage to a plurality of data lines of the liquid crystal panel assembly.

The gamma amplification device,

And an offset compensation gamma buffer for differentially amplifying the gray voltage, and sampling the offset voltage of the offset compensation gamma buffer using an auto zero circuit, and then removing the offset voltage.

At this time, the gamma amplifier,

And one or more offset compensation gamma buffers that output an output voltage obtained by differentially amplifying the gray voltages, sample their offset voltages using an autozero circuit, and then remove the offset voltages.

In addition, the gamma amplification device,

Further comprising a pulse generator for generating and outputting a pulse,

The one or more offset compensation gamma buffers may output an output voltage which is differentially amplified by mixing the gray voltage and the pulse.

In addition, the one or more offset compensation gamma buffer,

An amplifier having its own offset voltage; A first switch connected to an output terminal for outputting the output voltage; A second switch connected to an input terminal receiving the gray voltage; A first capacitor connected to the first switch, the amplifier, and the second switch to sample the offset voltage; And a third switch connected to the first capacitor and the output terminal.

In addition, the negative electrode of the first capacitor is connected to the drain electrode of the second switch, and the positive electrode of the first capacitor is connected to the negative electrode of the amplifier and the source electrode of the first switch. The drain electrode of the first switch may be connected to the output terminal, and the source electrode of the third switch may be connected to the drain electrode of the second switch.

In addition, the first switch and the second switch,

The third switch and the phase may be opposite to each other.

In addition, the first capacitor,

When the phases of the first switch and the second switch are high and the phases of the third switch are low, the first switch and the second switch are turned on and the third switch is turned off to the offset voltage. Can be sampled.

In addition, the offset voltage sampled by the first capacitor may be output as an output voltage of the output terminal.

In addition, the first capacitor,

When the phases of the first switch and the second switch are low and the phase of the third switch is high, the first switch and the second switch are turned off and the third switch is turned on to provide the offset voltage. Can be removed.

The output voltage of the output terminal may be equal to the input voltage by removing the offset voltage added to the input voltage input to the input terminal by the first capacitor.

The display device may further include a second capacitor connected between the source electrode and the drain electrode of the third switch.

The second capacitor may charge a difference voltage between an offset voltage sampled in the first capacitor and a voltage of the capacitor of the third switch itself when the third switch is turned from the turned on state to the turn off state. have.

According to another embodiment of the present invention, a method of driving a gamma amplifier is provided. The driving method,

An amplifier having its own offset voltage, a first switch connected to an output terminal for outputting an output voltage, a second switch connected to an input terminal for receiving a gray scale voltage, and connected to the first switch, the amplifier, and the second switch A driving method of a gamma amplifier including a first capacitor sampling an offset voltage, a third switch connected to the first capacitor and the output terminal.

The first switch and the second switch are turned on, the third switch is turned off to charge the first capacitor, and the first switch and the second switch are turned off, and the third switch Is turned on to discharge the first capacitor.

In addition, the step of charging the first capacitor,

When the phases of the first switch and the second switch are high and the phase of the third switch is low, the first switch and the second switch are turned on, and the third switch is turned off; and The first capacitor may include sampling the offset voltage.

In addition, after the first capacitor samples the offset voltage,

The method may further include outputting the offset voltage as an output voltage of the output terminal.

In addition, the step of discharging the first capacitor,

The offset voltage added to the gray voltage input by the input terminal may be discharged through the first capacitor.

In addition, after the step of discharging the first capacitor,

The method may further include outputting an input voltage from which the offset voltage is removed to an output voltage of the output terminal.

In addition, the gamma amplifier,

And a second capacitor connected between the source electrode and the drain electrode of the third switch.

After the step of discharging the first capacitor,

Charging the difference voltage between the offset voltage sampled on the first capacitor and the voltage of the capacitor of the third switch itself when the second capacitor is turned from the turned-on state when the third switch is turned on. can do.

According to another embodiment of the present invention, a liquid crystal display device is provided. The liquid crystal display device includes: a liquid crystal panel assembly including a plurality of pixels displaying an image according to a data signal in response to a gate signal, a plurality of gate lines connected to the plurality of pixels, and a plurality of data lines, respectively; A data driver configured to generate a data voltage and transmit the data voltage to the plurality of data lines; And a gray voltage generator which generates a gray voltage related to the luminance of the pixel and outputs the gray voltage to the data driver.

The data driver,

A gamma string part composed of a plurality of resistors generating an analog voltage; A digital-to-analog converter that selects an output voltage corresponding to an input bit from the output voltage output by the gamma string unit and converts the output voltage into an analog form; A buffer amplifier for differentially amplifying an output voltage output from the digital-to-analog converter and outputting the differential voltage to the plurality of data lines; And an offset compensation gamma buffer configured to output an output voltage obtained by differentially amplifying the gray voltage input from the gray voltage generator to the gamma string unit, and after sampling the offset voltage of the offset compensation gamma buffer using an auto zero circuit. , Remove.

In addition, the gamma amplification device,

A pulse generator for generating and outputting a pulse; And one or more offset compensation gamma buffers that output the differentially amplified output voltages by mixing the gray voltages and the pulses, and sampling and removing the offset voltages using an auto zero circuit.

In addition, the one or more offset compensation gamma buffer,

An amplifier having its own offset voltage; A first switch having a drain electrode connected to an output terminal for outputting the output voltage; A second switch having a source electrode connected to an input terminal receiving the gray voltage; A first capacitor connected to a drain electrode of the second switch and a positive electrode connected to a negative electrode of the amplifier and a source electrode of the first switch to sample the offset voltage; And a third switch having a source electrode connected to the drain electrode of the second switch and the negative electrode of the first capacitor, and the drain electrode being connected to the drain electrode of the first switch and the output terminal. .

In addition, the one or more offset compensation gamma buffer,

The display device may further include a second capacitor connected between the source electrode and the drain electrode of the third switch.

In addition, the second capacitor,

When the third switch is turned from the turned on state, the difference voltage between the offset voltage sampled by the first capacitor and the voltage of the capacitor of the third switch itself may be charged.

According to an embodiment of the present invention, the problem caused by the difference between the offset voltage of the gamma amplifier embedded in the data driver and the peaking problem due to the feed through is used by using an auto zero circuit. I can solve it.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.
2 is an equivalent circuit diagram of one display pixel in a liquid crystal display according to an exemplary embodiment of the present invention.
3 is a block diagram illustrating an internal configuration of a data driver according to an exemplary embodiment of the present invention.
4, 5 and 6 are circuit diagrams of the offset compensation gamma buffer of FIG.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of one display pixel in a liquid crystal display according to an exemplary embodiment of the present invention.

As illustrated in FIG. 1, the liquid crystal display includes a gate driver 200 connected to a liquid crystal panel assembly 100, a data driver 300, and a gray voltage generator connected to the data driver 300. 400, and a timing controller 500 for controlling them 200 and 300.

The liquid crystal panel assembly 100 includes a plurality of signal lines G ₁ -G _n , D ₁ -D _m and a plurality of pixels PX connected to the signal lines and arranged in a substantially matrix form in an equivalent circuit. Include. The plurality of signal lines G _1- G _n and D ₁ -D _m are a plurality of gate lines G ₁ -G _n and a data signal that transfer gate signals V _g1 -V _gn , also referred to as "scan signals." That is, it includes a plurality of data lines (D _1- D _m ) for transmitting a data voltage.

Referring to FIG. 2, each pixel PX, for example, the i-th (i = 1, 2, ---, n) gate line G _i and the j-th (j = 1, 2, ... m The pixel PX connected to the data line D _j includes a switching element Q connected to the signal lines G _i and D _j , a liquid crystal capacitor C _lc , and a storage capacitor Cst connected thereto. The storage capacitor Cst can be omitted if necessary.

The switching element Q is a three-terminal element of a thin film transistor or the like provided in the lower panel 111. The control terminal is connected to the gate line G _i , and the input terminal is connected to the data line D _j . The output terminal is connected to the liquid crystal capacitor C _lc and the storage capacitor Cst.

The liquid crystal capacitor Clc has two terminals, the common electrode CE of the upper panel 112 and the pixel electrode PE of the lower panel 111, and the liquid crystal layer 113 between the two electrodes PE and CE. It functions as a dielectric.

The pixel electrode PE is connected to the switching element Q, and the common electrode CE is formed on the entire surface of the upper panel 112 and receives the common voltage Vcom.

Unlike in FIG. 2, the common electrode CE may be provided in the lower panel 111. In this case, at least one of the two electrodes PE and CE may be formed in a linear or bar shape.

The storage capacitor Cst, which serves as an auxiliary part of the liquid crystal capacitor Clc, is formed by overlapping a separate signal line (not shown) and the pixel electrode PE provided on the upper panel 112 with an insulator interposed therebetween. A predetermined voltage such as the common voltage Vcom is applied to the separate signal line.

However, the storage capacitor Cst may be formed such that the pixel electrode PE overlaps the shear scan line directly above the insulator.

In order to implement color display, each pixel PX may uniquely display one of the primary colors (spatial division), or each display pixel PX may alternately display the primary colors according to time. (Time division) The spatial and temporal sum of these primary colors allows the desired color to be recognized.

Examples of the primary colors may include three primary colors such as red, green, and blue. In the case of spatial division, three display pixels representing red, green, and blue are gathered to form a dot, which is a basic unit of an image.

2 illustrates that each pixel PX includes a color filter CF representing one of the primary colors in an area of the upper panel 212 as an example of spatial division. Alternatively, the color filter CF may be disposed above or below the pixel electrode PE of the lower panel 111.

At least one polarizer (not shown) for polarizing light is provided on an outer surface of the liquid crystal panel assembly 100.

Referring back to FIG. 1, the gate driver 200 controls the transfer time of the gate signals V _g1- V _gn applied to the gate lines G _1- G _n connected to the liquid crystal panel assembly 100. do.

Here, the gate signals V _g1- V _{gn consist} of a combination of the gate on voltage Von and the gate off voltage Voff.

The data driver 300 is connected to the data lines D ₁ -D _m of the liquid crystal panel assembly 100, selects a gray voltage from the gray voltage generator 400, and uses the data line D _1- as a data signal. D _m ). However, when the gray voltage generator 400 provides only a predetermined number of reference gray voltages instead of providing all of the voltages for all grays, the data driver 300 divides the reference gray voltages to divide the gray voltages for all grays. Generate and select the data signal from it.

The gray voltage generator 400 generates a total gray voltage or a limited number of gray voltages (hereinafter, referred to as a reference gray voltage) related to the luminance of the pixel PX.

The signal controller 500 controls the gate driver 200 and the data driver 300. The signal controller 500 receives input image signals R, G, and B and an input control signal for controlling the display thereof from an external graphic controller (not shown). The input image signals R, G, and B contain luminance information of each pixel PX, and luminance has a predetermined number, for example, 1024 (= 2 ¹⁰ ), 256 (= 2 ⁸ ), or 64 ( = 2 ⁶ ) There are grays. Examples of the input control signal include a vertical sync signal Vsync, a horizontal sync signal Hsync, a main clock signal MCLK, and the like.

The signal controller 500 appropriately processes the input image signals R, G and B based on the input image signals R, G and B and the input control signal according to the operating conditions of the liquid crystal panel assembly 100, and controls the gate. After generating the signal CONT1 and the data control signal CONT2, the gate control signal CONT1 is sent to the gate driver 200, and the data control signal CONT2 and the processed image signal DAT are transmitted to the data driver 300. Export to). The gate control signal CONT1 according to the exemplary embodiment of the present invention may include a scan start signal (Gate Start Verticle, GSV) indicating the start of scanning, a gate clock signal (GSC) and a gate controlling the output period of the gate-on voltage (Von). It includes an output enable signal (Gate Output Enable, GOE) that defines the duration of the on voltage (Von).

The gate driver 200 and the data driver 300 may be directly mounted on the liquid crystal panel assembly 100 in the form of at least one integrated circuit chip, or may be mounted on a flexible printed circuit film (not shown). It may be mounted and attached to the liquid crystal panel assembly 100 in the form of a tape carrier package (TCP), or may be mounted on a separate printed circuit board (not shown). Alternatively, the gate driver 200 and the data driver 300 are integrated in the liquid crystal panel assembly 100 together with the plurality of signal lines G ₁ -G _n , D ₁ -D _m , and the thin film transistor switching element Q. May be

3 is a block diagram illustrating an internal configuration of a data driver according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the data driver 300 includes a gamma amplifier 310, a gamma string unit 330, a digital-analog converter (DAC) 350, and a buffer amplifier 370. . As such, since the data driver 300 includes the gamma amplifier 310, a cost can be reduced by reducing wiring in the liquid crystal display.

In the meantime, each component of the data driver 300 will be described. The gamma string unit 330 is composed of a plurality of resistors for making an analog voltage required for each node with a resistance ratio.

The digital-to-analog converter 350 selects a voltage output from the gamma string unit 330 according to a digital code. That is, a gamma voltage corresponding to each input digital bit data is selected and output. The gamma voltage is used as the reference voltage to generate the analog voltage.

The buffer amplifier 370 supplies a voltage converted to the analog form through the digital analog converter 350 to the respective data lines. The buffer amplifier 370 includes a buffer for minimizing the attenuation of the voltage, and the voltage converted to the analog form. Is stabilized (or differentially amplified) and output.

In addition, the gamma amplifier 310 includes a pulse generator 311 and a plurality of offset compensation gamma buffers 313.

In this case, the plurality of offset compensation gamma buffers 313 are buffers for outputting an input voltage input to a positive (+) input terminal or a negative (-) input terminal as an output voltage. The plurality of offset compensation gamma buffers 313 are received from the gray voltage generator 400. The gradation voltage and the pulse generated by the pulse generator 311 are mixed and differentially amplified and output to the gamma string unit 330. As such, the gamma voltage output to the gamma string part 330 is a voltage of a plurality of levels, and is used as a reference voltage for generating an analog voltage corresponding to digital bit data.

The number of offset compensation gamma buffers 313 is equal to the number of voltages of the multiple levels, and the offset compensation gamma buffer 313 is a gamma string of voltages of a plurality of levels with a fairly stable voltage value in order to prevent noise or screen shaking on the screen. Supply to the unit 330.

Here, the offset compensation gamma buffer 313 uses an auto zero circuit to prevent dimming of the screen due to the difference in the offset between the data drivers 300.

At this time, the auto zero circuit stores (or samples) the offset voltage of the offset compensation gamma buffer 313 in the capacitor at several uS or less based on the load signal, and compensates for the zero offset ( It is used as the actual output of the data driver 300 in the section maintaining zero offset), and then cancels. The circuit of the offset compensation gamma buffer 313 using the auto zero circuit will be described in detail as follows.

4 through 6 are circuit diagrams of the offset compensation gamma buffer of FIG. 3, respectively.

First, referring to FIG. 4, in the offset compensation gamma buffer 313 of the gamma amplifier 300, an amplifier 313-3, which receives an input voltage V _in through the input terminal 313-1, receives an input voltage. The output voltage V _{out obtained} by differentially amplifying (V _in ) is output through the output terminal 313-5.

The offset compensation gamma buffer 313 includes three switches T ₁ , T ₂ , T ₃ , a hold capacitor C _H , and a feed through capacitor C _F.

In this case, the drain electrode of the first switch T ₁ is connected to the output terminal 313-5, and the source electrode is connected to the positive electrode of the hold capacitor C _H. And a hold capacitor (+) electrode of the amplifier (313-3) of (C _H), a drain electrode of the electrode of the second switch (T ₂₎ - - () of the electrode is connected with the hold capacitor (C _H) () Connected with In this case, the source electrode of the second switch T ₂ is connected to the input terminal 313-1. The source electrode of the third switch T ₃ is connected to the drain electrode of the second switch T ₂ and the negative electrode of the hold capacitor C _H , and the drain electrode of the third switch T _{3 is} formed of a first electrode. 1 is connected to the drain electrode and the output terminal (313-5) of the switch (T ₁ ).

Here, the first switch T ₁ and the second switch T ₂ have the same phase as θ ₁ , and the third switch T ₃ has a phase of θ ₂ . At this time, the phases θ ₁ and θ ₂ do not overlap with each other, and have phases opposite to each other. That is, when the phase θ ₁ is high, the phase θ ₂ becomes low, and when the phase θ ₁ is low, the phase θ ₂ becomes high.

In addition, the hold capacitor C _H charges the offset voltage V _OS of the amplifier 313-3. That is, as shown in FIG. 5, the hold capacitor C _H is turned on while the first switch T ₁ and the second switch T ₂ are turned on while θ 1 is high. ₃ ) is turned off to sample the offset voltage (V _OS ). At this time, the voltage passing through the holding capacitor (C _H ) is the offset voltage (V _OS ), the same as the output voltage (V _out ).

In addition, as shown in FIG. 6, the hold capacitor C _H has the first switch T ₁ and the second switch T ₂ turned off and the third switch T while θ ₂ is high. ₃ ) is turned on. At this time, the output voltage (V _out) is the offset voltage (V _OS) added to the input voltage (V _IN) is to remove (cancel) by a hold capacitor (C _H) is eventually equal to the input voltage (V _IN).

As such, the offset compensation gamma buffer 313 of the gamma amplifying device 300 uses an auto zero circuit and offsets the hold capacitor C _H for several uS in a load section of the data driver 300. The voltage V _OS is sampled and then θ ₂ cancels while High. In addition, the offset voltage V _OS sampled to the hold capacitor C _H is used as the actual output of the data driver 300 in a section maintaining the compensated zero offset.

Due to the characteristics of the data driver 300, the settling time may be several uS according to the load of the panel, but the data driver is sampled because the offset is sampled before the settling. It does not affect the characteristics of 300.

Referring back to FIG. 4, a feed through capacitor C _F is connected between the source electrode and the drain electrode of the third switch T ₃ .

In this case, the feed-through capacitor C _F reduces the influence of charge feed through as the three switches T ₁ , T ₂ , and T ₃ are turned on or off. That is, the third switch T ₃ of the compensation period is connected to both ends of the third switch T ₃ to eliminate the peaking caused by the charge feed through.

Here, the charge feed through (charge feedthrough) is a phenomenon occurring between the third switch capacitor between (T ₃₎ the gate and source / drain (Cgd / Cgs) and the hold capacitor (C _H), the third switch (T ₃ ) Is a phenomenon in which unwanted voltage is added to the holding capacitor (C _H ) as it is switched from turn on to turn off. At this time, the feed-through capacitor (C _F ) removes the picking due to the voltage so added.

That is, as shown in FIG. 6, when the third switch T ₃ is turned on, the capacitor Cgd between the offset voltage sampled by the hold capacitor C _H and the gate and the source / drain of the third switch T ₃ . / Cgs) charges the difference voltage between voltages. Subsequently, as shown in FIG. 5, when the third switch T ₃ is turned off, the difference voltage charged in the feedthrough capacitor C _F is discharged.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (23)

A gamma amplifier configured to receive a gray voltage and output an output voltage obtained by differentially amplifying the gray voltage;
A gamma string unit including a plurality of resistors receiving the output voltage from the gamma amplifier to generate an analog voltage;
A digital-to-analog converter that selects an output voltage corresponding to an input bit from the output voltage output by the gamma string unit and converts the output voltage into an analog form; And
And a buffer amplifier for differentially amplifying the output voltage output from the digital-to-analog converter and outputting the output voltage to a plurality of data lines of the liquid crystal panel assembly.
The gamma amplification device,
And an offset compensation gamma buffer for differentially amplifying the gray level voltage, and after sampling the offset voltage of the offset compensation gamma buffer using an auto zero circuit. The method of claim 1,
The gamma amplification device,
And at least one offset compensation gamma buffer for outputting an output voltage obtained by differentially amplifying the gray voltage, sampling the offset voltage thereof using an autozero circuit, and then removing the offset voltage. The method of claim 2,
The gamma amplification device,
Further comprising a pulse generator for generating and outputting a pulse,
The one or more offset compensation gamma buffers,
And an output voltage obtained by differentially amplifying the gray level voltage and the pulse. The method of claim 2,
The one or more offset compensation gamma buffers,
An amplifier having its own offset voltage;
A first switch connected to an output terminal for outputting the output voltage;
A second switch connected to an input terminal receiving the gray voltage;
A first capacitor connected to the first switch, the amplifier, and the second switch to sample the offset voltage; And
A third switch connected to the first capacitor and the output terminal
Driving device comprising a. 5. The method of claim 4,
The negative electrode of the first capacitor is connected to the drain electrode of the second switch, the positive electrode of the first capacitor is connected to the negative electrode of the amplifier and the source electrode of the first switch, The drain electrode of the first switch is connected to the output terminal, the source electrode of the third switch is connected to the drain electrode of the second switch. The method of claim 5,
The first switch and the second switch,
And a driving device having a phase opposite to that of the third switch. The method according to claim 6,
Wherein the first capacitor comprises:
When the phases of the first switch and the second switch are high and the phases of the third switch are low, the first switch and the second switch are turned on and the third switch is turned off to the offset voltage. Driving device for sampling the. The method of claim 7, wherein
And the offset voltage sampled by the first capacitor is output as an output voltage of the output terminal. The method of claim 7, wherein
Wherein the first capacitor comprises:
When the phases of the first switch and the second switch are low and the phase of the third switch is high, the first switch and the second switch are turned off and the third switch is turned on to provide the offset voltage. Driving device to remove it. 10. The method of claim 9,
And an output voltage of the output terminal is equal to the input voltage by removing an offset voltage added to an input voltage input to the input terminal by the first capacitor. The method according to claim 6,
And a second capacitor connected between the source electrode and the drain electrode of the third switch. The method of claim 11,
Wherein the second capacitor comprises:
And a third driving device configured to charge a difference voltage between an offset voltage sampled by the first capacitor and a voltage of a capacitor of the third switch itself when the third switch is turned from a turn on state to a turn off state. An amplifier having its own offset voltage, a first switch connected to an output terminal for outputting an output voltage, a second switch connected to an input terminal for receiving a gray scale voltage, and connected to the first switch, the amplifier, and the second switch A driving method of a gamma amplifier including a first capacitor sampling an offset voltage, a third switch connected to the first capacitor and the output terminal.
The first switch and the second switch are turned on, and the third switch is turned off to charge the first capacitor, and
The first switch and the second switch are turned off, and the third switch is turned on to discharge the first capacitor.
Method of driving a gamma amplifier comprising a. The method of claim 13,
The step of charging the first capacitor,
When the phases of the first switch and the second switch are high and the phase of the third switch is low, the first switch and the second switch are turned on, and the third switch is turned off; and
Sampling the offset voltage by the first capacitor
Method of driving a gamma amplifier comprising a. 15. The method of claim 14,
After the first capacitor samples the offset voltage,
Outputting the offset voltage as an output voltage of the output terminal
The method of driving a gamma amplifier further comprising. 15. The method of claim 14,
Discharging the first capacitor,
And the offset voltage added to the gray voltage received by the input terminal is discharged through the first capacitor. 17. The method of claim 16,
After the step of discharging the first capacitor,
Outputting an input voltage from which the offset voltage is removed to an output voltage of the output terminal
The method of driving a gamma amplifier further comprising. 18. The method of claim 17,
The gamma amplifier,
And a second capacitor connected between the source electrode and the drain electrode of the third switch.
After the step of discharging the first capacitor,
Charging the difference voltage between the offset voltage sampled on the first capacitor and the voltage of the capacitor of the third switch itself when the second capacitor is turned from the turned-on state when the third switch is turned on.
The method of driving a gamma amplifier further comprising. A liquid crystal panel assembly including a plurality of pixels displaying an image according to a data signal in response to a gate signal, a plurality of gate lines connected to the plurality of pixels, and a plurality of data lines, respectively;
A data driver configured to generate a data voltage and transmit the data voltage to the plurality of data lines; And
A gray voltage generator which generates a gray voltage related to the luminance of the pixel and outputs the gray voltage to the data driver;
The data driver may include:
A gamma string part composed of a plurality of resistors generating an analog voltage;
A digital-to-analog converter that selects an output voltage corresponding to an input bit from the output voltage output by the gamma string unit and converts the output voltage into an analog form;
A buffer amplifier for differentially amplifying an output voltage output from the digital-to-analog converter and outputting the differential voltage to the plurality of data lines; And
An offset compensation gamma buffer configured to output an output voltage obtained by differentially amplifying the gray voltage input from the gray voltage generator to the gamma string unit, and after sampling the offset voltage of the offset compensation gamma buffer using an auto zero circuit, Removing gamma amplification device
Liquid crystal display comprising a. 20. The method of claim 19,
The gamma amplification device,
A pulse generator for generating and outputting a pulse; And
One or more offset compensation gamma buffers that output the differentially amplified output voltages by mixing the gray voltages and the pulses, and sampling and removing the offset voltages using an autozero circuit.
Liquid crystal display comprising a. 21. The method of claim 20,
The one or more offset compensation gamma buffers,
An amplifier having its own offset voltage;
A first switch having a drain electrode connected to an output terminal for outputting the output voltage;
A second switch having a source electrode connected to an input terminal receiving the gray voltage;
A first capacitor connected to a drain electrode of the second switch and a positive electrode connected to a negative electrode of the amplifier and a source electrode of the first switch to sample the offset voltage; And
A third switch having a source electrode connected to a drain electrode of the second switch and a negative electrode of the first capacitor, and a drain electrode connected to a drain electrode of the first switch and the output terminal;
Liquid crystal display comprising a. The method of claim 21,
The one or more offset compensation gamma buffers,
And a second capacitor connected between the source electrode and the drain electrode of the third switch. The method of claim 22,
Wherein the second capacitor comprises:
And a second voltage charged between the offset voltage sampled in the first capacitor and the voltage of the capacitor of the third switch itself when the third switch is turned from the turned on state.

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