KR20130014754A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: An LCD(Liquid Crystal Display) device is provided to reduce screen distortion like cross-talk or flicker by driving a vertical dot and horizontal dot inversion mode. CONSTITUTION: A first common voltage is supplied to a plurality of first common voltage lines(CL1). A second common voltage(Vcom2) is supplied to a plurality of second common voltage lines(CL2). A plurality of first contact holes exposes a part of the first common voltage line. A plurality of second contact holes exposes a part of the second common voltage line. A first connection line(LL1), a second connection(LL2), or a third connection line(LL3) supplies each pixel to the common voltage supplied to the first and the second common voltage line. [Reference numerals] (AA) First embodiment

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device capable of increasing aperture ratio and reducing cross talk by driving dot inversion while eliminating a common voltage application TFT.

Recently, in order to reduce the circuit cost of liquid crystal displays, instead of doubling the number of gate lines, the number of data lines has been reduced by half to double the number of data drive ICs. ) Liquid crystal display is being developed.

Meanwhile, in the liquid crystal display according to the related art, inversion driving and common voltage alternating current driving are applied. Inversion driving is a technique of preventing deterioration of liquid crystal by alternately applying data voltages having opposite polarities to neighboring pixels. Common voltage alternating current driving is a technology that reduces power consumption during inversion driving. By reducing the swing width of the data voltage by half the common voltage, the power consumption of the data drive IC can be reduced.

Hereinafter, the DRD type liquid crystal display device to which the common voltage AC drive is applied will be described. The liquid crystal display described below is a transverse electric field type liquid crystal display device.

The DRD type liquid crystal display device with the common voltage alternating current drive is a liquid crystal panel that defines m × n pixels (m and n are natural numbers) at the intersection of 2n gate lines and m / 2 data lines, and And a gate driver and a data driver for driving the gate lines and the data lines to be driven in a version manner.

The liquid crystal panel includes a plurality of common lines arranged side by side with data lines and arranged between the data lines to apply a common voltage to each pixel. A plurality of common lines are applied with a common voltage provided from the outside, and a common voltage having an inverted phase is applied to neighboring common lines.

Meanwhile, each pixel exposes a common line through a contact hole or connects the exposed common line to the pixel through a contact hole or a method including a thin film transistor (TFT) to receive a common voltage from an adjacent common line. The method is being applied.

However, the liquid crystal display as described above has the following problems.

That is, in the case where each pixel is provided with the common voltage applying TFT, the common voltage is shaken due to the parasitic coupling phenomenon of the TFT, resulting in poor image quality. In addition, the TFT provided in each pixel causes a reduction in aperture ratio.

In addition, since each pixel is applied with a common voltage through the contact hole, a common voltage applies a common voltage to two columns of pixels provided on the left and right sides of the common line, and thus the data voltage and the common voltage in pixel units of two columns. Column inversion driving is performed in which the polarity of is reversed. However, column inversion driving has a disadvantage in that it is vulnerable to screen distortion such as flicker or cross talk as compared to dot inversion driving.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device capable of increasing aperture ratio and reducing cross talk by driving dot inversion while eliminating a common voltage application TFT.

In order to achieve the above object, a liquid crystal display according to an exemplary embodiment of the present invention may include two gate lines arranged in a first direction and m / 2 data lines arranged in a second direction perpendicular to the first direction. A liquid crystal including a plurality of first and second common voltage lines that define a plurality of pixels arranged in an intersection n rows m columns (n and m are natural numbers) and are arranged in the second direction on the left and right sides of each data line A panel; A common voltage generator configured to apply first and second common voltages having inverted phases to each of the plurality of first and second common voltage lines and inverted in units of frames; And a gate driver and a data driver for driving the gate lines and the data lines such that the liquid crystal panel is driven in a vertical dot and a horizontal two dot inversion scheme. A plurality of first contact holes exposing a portion of the first common voltage line and a plurality of second contact holes exposing a portion of the second common voltage line; Each of the pixels includes a pixel electrode and a common electrode arranged between the first and second common voltage lines and the data lines and forming a horizontal electric field; The common electrodes are directly connected to the first contact hole or the second contact hole through a first connection line to receive the first common voltage or the second common voltage, and adjacent common electrodes receiving the same common voltage. Characterized in that they are connected to each other.

Pixels arranged on the left and right sides of the respective data lines with respect to an arbitrary row are characterized in that data voltages having the same polarity are applied.

The first connection line is arranged in an odd-numbered row and connects the pixel arranged on the left side of the first and second common voltage lines with the first contact hole or the second contact hole, and is arranged in an even-numbered row. The pixel arranged on the right side of the first and second common voltage lines and the first contact hole or the second contact hole are connected to each other.

The common electrodes of the pixels arranged on the left and right sides of each data line may be connected to each other through a second connection line.

The common electrodes of the pixels arranged on the left and right sides of the first and second common voltage lines may be connected to each other in a zigzag form through a third connection line.

Pixels arranged on the left and right sides of each of the first and second common voltage connection lines with respect to an arbitrary row are applied with data voltages having the same polarity.

The first connection line connects pixels arranged on left and right sides of the first and second common voltage lines and arranged in odd-numbered rows and the first contact hole or the second contact hole.

The common electrodes of the pixels disposed on the left and right sides of the first and second common voltage lines and arranged in the even-numbered rows may be connected to each other through a second connection line.

The common electrodes of the pixels arranged in a diagonal direction with respect to each of the data lines may be connected to each other through a third connection line.

The first to third connection lines and the common electrode may be formed on the same layer using the same material.

As described above, the present invention can reduce screen distortions such as flicker and crosstalk as compared to column inversion driving by vertical and horizontal two-dot inversion driving. In addition, AC power is driven to reduce the swing width of the data voltage, thereby reducing power consumption of the data driver. The aperture ratio can be increased by eliminating the common voltage application TFT. In addition, the common electrodes of the pixels may be connected to each other in a mesh form through the first to third connection lines to stabilize the common voltage.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.
FIG. 2 is a plan view illustrating a part of the liquid crystal panel shown in FIG. 1.
3 is a waveform diagram of first and second common voltages according to an exemplary embodiment.
4 illustrates the polarity of the data voltage according to the first embodiment of the present invention.
5 shows the polarity of the data voltage according to the second embodiment of the present invention.
6 is an equivalent circuit diagram of the liquid crystal panel 2 according to the first embodiment of the present invention.
FIG. 7 is a layout diagram of the liquid crystal panel 2 shown in FIG. 6.
8 is a cross-sectional view taken along line AA ′ of FIG. 7.
9 is an equivalent circuit diagram of the liquid crystal panel 2 according to the second embodiment of the present invention.
FIG. 10 is a layout diagram of the liquid crystal panel 2 shown in FIG. 9.

Hereinafter, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention. 2 is a plan view illustrating a part of the liquid crystal panel illustrated in FIG. 1.

1 and 2, the liquid crystal display according to the exemplary embodiment includes a liquid crystal panel 2, a gate driver 4, a data driver 6, and a common voltage generator 8.

The liquid crystal panel 2 includes an upper substrate and a lower substrate, and a liquid crystal layer provided between the upper substrate and the lower substrate.

The pixel array is formed on the lower substrate. The pixel array includes 2n gate lines GL1 to GL2n arranged in a first direction (eg, a horizontal direction) and m / 2 arranged in a second direction (eg, a vertical direction) perpendicular to the first direction. Data lines DL1 to DLm / 2. In the non-display area of the lower substrate, first and second common lines (not shown) in the form of bars are provided to receive the common voltages Vcom1 and Vcom2 from the common voltage generator 8. The first and second common lines are connected to the plurality of common voltage lines CL1 and CL2, and the plurality of common voltage lines CL1 and CL2 are connected in the second direction from the left and right sides of the data lines DL1 to DLm / 2. Is arranged.

The gate lines GL1 to GL2n and the data lines DL1 to DLm / 2 cross each other to define a plurality of pixels arranged in n rows and m columns (n and m are natural numbers). Each pixel includes a TFT, which supplies a data voltage provided from the data lines DL1 to DLm / 2 to the liquid crystal cell Clc in response to a scan pulse provided from the gate lines GL1 to GL2n.

The liquid crystal cell Clc includes a pixel electrode 10 to which a data voltage is applied, and a common electrode 12 forming a transverse electric field together with the pixel electrode 10. The common electrode 12 receives the common voltages Vcom1 and Vcom2 from adjacent common voltage lines CL1 and CL2. The common electrodes 12 have a mesh shape in which adjacent common electrodes 12 that receive the same common voltages Vcom1 and Vcom2 are connected to each other, which will be described later in detail. Meanwhile, each pixel may further include a storage capacitor Cst for maintaining a voltage charged in the liquid crystal cell Clc.

On the upper substrate, a color filter array corresponding to the pixel region where the TFT is formed on the lower substrate, and a black matrix covering the gate lines GL1 to GL2n and the data lines DL1 to DLm / 2 are formed by partitioning them.

The gate driver 4 and the data driver 6 drive the gate lines GL1 to GL2n and the data lines DL1 to DLm / 2 so that the liquid crystal panel 2 is driven in a vertical dot and horizontal two dot inversion scheme. Drive.

The gate driver 4 includes a shift register, which sequentially outputs a scan signal having a pulse width of about one horizontal period so as to be synchronized with the positive or negative data voltage output from the data driver 6.

The common voltage generator 8 generates common voltages Vcom1 and Vcom2. At this time, the common voltages Vcom1 and Vcom2 generated by the common voltage generator 8 are applied to the plurality of common voltage lines CL1 and CL2 via the first and second common lines. As illustrated in FIG. 3, the common voltages Vcom1 and Vcom2 include a first common voltage Vcom1 and a second common voltage Vcom2 having phases inverted from each other and inverted in units of frames. For example, when the first common voltage Vcom1 is set to a negative voltage in the first frame, the second common voltage Vcom2 is set to a positive voltage, and the first common voltage Vcom1 is set in the second frame. The voltage of the positive polarity is set and the second common voltage Vcom2 is set to the voltage of the negative polarity.

The common voltage generator 8 alternately applies the first and second common voltages Vcom1 and Vcom2 to the plurality of common voltage lines CL1 and CL2. For example, the common voltage generator 8 applies the first common voltage Vcom1 to the first common voltage line CL1, and applies the second common voltage Vcom2 to the second common voltage line CL2. can do.

The plurality of common voltage lines CL1 and CL2 include first and second common voltage lines CL1 and CL2. For example, the first common voltage line CL1 is arranged to the left of the odd-numbered data lines DL1, DL3, DL5,... And to the right of the even-numbered data lines DL2, DL4, DL6,. The second common voltage line CL2 is arranged to the right of the odd-numbered data lines DL1, DL3, DL5,... And to the left of the even-numbered data lines DL2, DL4, DL6,.

Pixels are arranged between the plurality of common voltage lines CL1 and CL2 and the data lines DL1 to DLm / 2. Accordingly, two pixels are arranged in a row unit between each data line DL1-DLm / 2, and two pixels are arranged in a row unit between the first and second common voltage lines CL1 and CL2. do. Meanwhile, the plurality of common voltage lines CL1 and CL2 include contact holes H1 and H2 exposing portions of the common voltage lines CL1 and CL2 to supply the common voltages Vcom1 and Vcom2 to each pixel, which will be described later.

The data driver 6 performs inversion driving to prevent deterioration of the liquid crystal. Specifically, the data driver 6 generates positive data voltages and negative data voltages using image data provided from the outside and supplies the generated data voltages to the plurality of data lines DL1 to DLm / 2. The positive and negative data voltages have opposite polarities with respect to the common voltages Vcom1 and Vcom2 and have the same absolute value.

The data driver 6 alternately outputs positive and negative data voltages through the output channel. At this time, the polarity of the data voltage output from each channel is inverted every two horizontal periods, and the polarity is inverted every frame. Data voltages output from adjacent channels are opposite in polarity. Accordingly, the present invention can be divided into the first and second embodiments according to the output order of the data voltage applied to each pixel, as follows.

4 illustrates the polarity of the data voltage according to the first embodiment of the present invention, and FIG. 5 illustrates the polarity of the data voltage according to the second embodiment of the present invention. In FIG. 4 and FIG. 5, "+" represents a positive data voltage and "-" represents a negative data voltage.

According to the first embodiment, during an arbitrary frame period, the data voltage is changed to “++-++-… in the odd-numbered data lines DL1, DL3, DL5, ... as shown in FIG. ”In order, and on the even-numbered data lines DL2, DL4, DL6,…,“-++-++… ”. Are applied in that order. Accordingly, in the first embodiment, a pixel in which data voltages applied to each pixel are applied in a vertical dot and a horizontal two dot inversion scheme, but arranged on the left and right sides of each data line DL1 to DLm / 2 for an arbitrary row. A data voltage of the same polarity is applied.

According to the second embodiment, the data voltage applied to the odd-numbered data lines DL1, DL3, DL5,... As shown in FIG. 5 during the arbitrary frame period is “+-++- +… ", And the data voltages applied to the even-numbered data lines DL2, DL4, DL6, ... are"-++-++-... Are applied in that order. Accordingly, in the second embodiment, the data voltage applied to each pixel is applied in a vertical dot and a horizontal two dot inversion scheme, and the left and right sides of each of the first and second common voltage lines CL1 and CL2 are applied to any row. Data voltages of the same polarity are applied to the pixels arranged in the.

In the first and second embodiments as described above, the vertical distortion and the horizontal two-dot inversion driving have an effect of reducing screen distortion, such as flicker or crosstalk, compared to the column inversion driving. In addition, the first and second embodiments reduce the swing width of the data voltage by alternatingly driving the common voltages Vcom1 and Vcom2. When negative data voltages are applied to each pixel, the common voltages Vcom1 and Vcom2 are positive. When the positive data voltages are applied to each pixel, the common voltages Vcom1 and Vcom2 are applied. Accordingly, the swing width of the data voltage can be reduced while maintaining the same liquid crystal drive voltage as the conventional one, thereby reducing power consumption of the data driver 6.

Hereinafter, the first embodiment will be described in more detail.

6 is an equivalent circuit diagram of the liquid crystal panel 2 according to the first embodiment of the present invention, and FIG. 7 is a layout diagram of the liquid crystal panel 2 shown in FIG. 8 is a cross-sectional view taken along line AA ′ of FIG. 7.

6 and 7, the first embodiment applies a data voltage in a vertical dot and a horizontal two dot inversion method, and at the same time, the common voltages Vcom1 and Vcom2 also use a vertical dot and a horizontal two dot inversion method. Is authorized. That is, the first embodiment alternately applies the first and second common voltages Vcom1 and Vcom2 for each vertical dot (pixel) and two horizontal dots.

To this end, the first embodiment includes a plurality of first common voltage lines CL1 to which the first common voltage Vcom1 is applied and a plurality of second common voltage lines CL2 to which the second common voltage Vcom2 is applied. And a plurality of first contact holes H1 exposing a part of the first common voltage line CL1, a plurality of second contact holes H2 exposing a part of the second common voltage line CL2, and a first And first to third connection lines LL1 for supplying the common voltages applied to the second common voltage lines CL1 and CL2 to each pixel.

The first connection line LL1 connects the first and second common voltage lines CL1 and CL2 to the pixels arranged in odd-numbered rows and to the left of the first and second common voltage lines CL1 and CL2. do. The first and second common voltage lines CL1 and CL2 and the pixels arranged in even-numbered rows and arranged to the right of the first and second common voltage lines CL1 and CL2 are connected to each other. In this case, one side of the first connection line LL1 is connected to the first contact hole H1 or the second contact hole H2, and the other side thereof is connected to the common electrode 12 provided in the pixel.

The second connection line LL2 connects the common electrodes 12 of the pixels arranged on the left and right sides of the data lines DL1 to DLm / 2.

The third connection line LL3 connects the common electrodes of the pixels arranged on the left and right sides of the first and second common voltage lines CL1 and CL2 to each other in a zigzag form.

In the first embodiment, when the common voltages Vcom1 and Vcom2 are applied to each pixel, the first and second contact holes H1 and H2 and the first to third connection lines LL1 to LL3 are used. Common voltages Vcom1 and Vcom2 are directly applied to the pixel. Accordingly, the first embodiment can increase the aperture ratio by eliminating the common voltage application TFT. In addition, the first to third connection lines LL1 to LL3 stably apply the common voltages Vcom1 and Vcom2 applied to each pixel by connecting the common electrodes 12 of the pixels to each other in a mesh form. can do.

Meanwhile, referring to FIG. 8, the cross-sectional structure of the first embodiment is as follows.

7 and 8, the lower substrate 100 includes gate lines GL1 to GL2n and data lines DL1 to DLm / 2 that intersect with the gate insulating layer 200 interposed therebetween, and are defined as intersections thereof. Pixel electrodes 10 and common electrodes 12 formed so as to form a horizontal electric field in the pixels, TFTs provided in each pixel, and first and second voltages for applying common voltages Vcom1 and Vcom2 to the common electrodes 12. 2 includes common voltage lines CL1 and CL2 and first to third connection lines LL1 to LL3.

The first and second common voltage lines CL1 and CL2 are formed on the same layer of the same material as the data lines DL1 to DLm / 2, and are formed parallel to the data lines DL1 to DLm / 2.

The TFT includes a gate electrode 14 protruding from the gate lines GL1 to GL2n, a source electrode 16 connected to the data lines DL1 to DLm / 2, and a drain electrode formed to be spaced apart from the source electrode 16. 18 and an active layer 20 forming a channel between the source and drain electrodes 16 and 18 and an ohmic contact layer 22 formed between each of the source and drain electrodes 16 and 18 and the active layer 20. Include.

The pixel electrode 10 is formed on the lower substrate 100 and is connected to the drain electrode 18 of the TFT through the third contact hole H3. The third contact hole H3 passes through the passivation layer 300 and the gate insulating layer 200 to expose a portion of the drain electrode 18 and a portion of the pixel electrode 10. In this case, the drain electrode 18 and the pixel electrode 10 exposed through the third contact hole H3 are connected to each other through the contact electrode 24.

The common electrode 12 is formed on the pixel electrode 10 and includes a plurality of slits. The common electrode 12 receives the common voltages Vcom1 and Vcom2 through the first to third connection lines LL1 to LL3. Among them, the first connection line LL1 is connected to the first and second contact holes H1 and H2 exposing portions of the first and second common voltage lines CL1 and CL2.

Here, the common electrode 12 and the first to third connection lines LL1 to LL3 are formed on the same layer of the same material.

Meanwhile, in the first embodiment, the pixel electrode 10 is formed at the bottom and the common electrode 12 is formed at the top, but is not limited thereto. The pixel electrode 10 is formed at the top and the common electrode 12 is located at the bottom. Can be formed.

Hereinafter, the second embodiment will be described in more detail.

FIG. 9 is an equivalent circuit diagram of the liquid crystal panel 2 according to the second embodiment of the present invention, and FIG. 10 is a layout diagram of the liquid crystal panel 2 shown in FIG.

9 and 10, the second embodiment applies a data voltage in a vertical dot and a horizontal two dot inversion method similarly to the first embodiment, and at the same time, the common voltages Vcom1 and Vcom2 are also vertical dots and horizontal. It is applied by the 2-dot inversion method. That is, the second embodiment alternately applies the first and second common voltages Vcom1 and Vcom2 for each vertical dot (pixel) and horizontal two dots.

To this end, the second embodiment includes a plurality of first common voltage lines CL1 to which the first common voltage Vcom1 is applied and a plurality of second common voltage lines CL2 to which the second common voltage Vcom2 is applied. And a plurality of first contact holes H1 exposing a part of the first common voltage line CL1, a plurality of second contact holes H2 exposing a part of the second common voltage line CL2, and a first And first to third connection lines LL1 for supplying the common voltages applied to the second common voltage lines CL1 and CL2 to each pixel.

The first connection line LL1 connects pixels arranged on the left and right sides of the first and second common voltage lines CL1 and CL2 and the first and second common voltage lines CL1 and CL2 and arranged in odd-numbered rows. do. In this case, one side of the first connection line LL1 is connected to the first contact hole H1 or the second contact hole H2, and the other side thereof is connected to the common electrode 12 provided in the pixel.

The second connection line LL2 connects the common electrodes 12 of the pixels arranged on the left and right sides of the first and second common voltage lines CL1 and CL2 and arranged in even-numbered rows.

The third connection line LL2 connects pixels arranged in a diagonal direction with respect to each data line DL1 to DLm / 2. In this case, the third connection line LL3 connects the common electrodes 12 of the pixels to each other.

In the second embodiment, when the common voltages Vcom1 and Vcom2 are applied to each pixel, the first and second contact holes H1 and H2 and the first to third connection lines LL1 to LL3 are used. Common voltages Vcom1 and Vcom2 are directly applied to the pixel. In addition, the first to third connection lines LL1 to LL3 stably apply the common voltages Vcom1 and Vcom2 applied to each pixel by connecting the common electrodes 12 of the pixels to each other in a mesh form. can do.

In the meantime, the description of the cross-sectional structure of the second embodiment will be replaced with the description mentioned in the first embodiment.

As described above, the present invention can reduce screen distortions such as flicker and crosstalk as compared to column inversion driving by vertical and horizontal two-dot inversion driving. The common voltages Vcom1 and Vcom2 are alternately driven to reduce the swing width of the data voltage, thereby reducing power consumption of the data driver 6. The aperture ratio can be increased by eliminating the common voltage application TFT. The common electrodes 12 of each pixel may be connected to each other in a mesh form through the first to third connection lines LL1 to LL3 to stabilize the common voltages Vcom1 and Vcom2.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of.

CL1: first common voltage line CL2: second common voltage line
LL1: first connection line LL2: second connection line
LL3: third connection line 6: data driver

Claims (10)

An intersection of 2n gate lines arranged in a first direction and m / 2 data lines arranged in a second direction perpendicular to the first direction, and a plurality of pixels arranged in n rows and m columns (n and m are natural numbers). A liquid crystal panel defining a plurality of first and second common voltage lines arranged in the second direction at left and right sides of each data line;
A common voltage generator configured to apply first and second common voltages having inverted phases to each of the plurality of first and second common voltage lines and inverted in units of frames; And
A gate driver and a data driver for driving the gate lines and the data lines to drive the liquid crystal panel in a vertical dot and a horizontal two dot inversion scheme;
A plurality of first contact holes exposing a portion of the first common voltage line and a plurality of second contact holes exposing a portion of the second common voltage line;
Each of the pixels includes a pixel electrode and a common electrode arranged between the first and second common voltage lines and the data lines and forming a horizontal electric field;
The common electrodes are directly connected to the first contact hole or the second contact hole through a first connection line to receive the first common voltage or the second common voltage, and adjacent common electrodes receiving the same common voltage. Liquid crystal display, characterized in that connected to each other. The method of claim 1,
And a data voltage of the same polarity is applied to pixels arranged on the left and right sides of each data line for an arbitrary row. The method of claim 2,
The first connection line
A pixel arranged in an odd-numbered row and arranged to the left of the first and second common voltage lines and the first contact hole or the second contact hole;
And a pixel arranged in an even-numbered row and arranged on the right side of the first and second common voltage lines and the first contact hole or the second contact hole. The method of claim 3, wherein
And a common electrode of pixels arranged on left and right sides of each data line are connected to each other through a second connection line. The method of claim 4, wherein
And a common electrode of pixels arranged at left and right sides of the first and second common voltage lines are connected to each other in a zigzag form through a third connection line. The method of claim 1,
And a data voltage having the same polarity is applied to pixels arranged on the left and right sides of each of the first and second common voltage connection lines with respect to an arbitrary row. The method according to claim 6,
The first connection line
And pixels arranged on left and right sides of the first and second common voltage lines and arranged in odd-numbered rows and the first contact hole or the second contact hole. The method of claim 7, wherein
And the common electrodes of the pixels arranged on the left and right sides of the first and second common voltage lines and arranged in the even-numbered rows are connected to each other through a second connection line. The method of claim 8,
And the common electrodes of the pixels arranged in a diagonal direction with respect to each data line are connected to each other through a third connection line. The method according to claim 5 or 9,
And the first to third connection lines and the common electrode are formed on the same layer using the same material.

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