KR20070081573A - Display device - Google Patents

Abstract

A display device is provided to reduce a gate off ripple difference between gate driving units by controlling the number of gate lines. A plurality of gate driving units(240) are connected to different numbers of gate lines(110). A driving signal unit(220) applies a gate driving signal to any one of the plurality of gate driving units. The plurality of gate driving units are arranged in a row, and the gate driving signal applied to one gate driving unit is sequentially transmitted to another adjacent gate driving unit. The number of gate lines connected to the gate driving units decreases in a direction in which the gate driving unit receives the gate driving signal from the driving signal unit.

Description

Display device {DISPLAY DEVICE}

1 is a schematic diagram of a display device according to an embodiment of the present invention;

2 is a graph illustrating a gate-off voltage waveform according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: display area 110: gate line

120: data line 210: signal controller

220: driving signal unit 230: gradation voltage generating unit

240: gate driver 250: data driver

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display apparatus, and more particularly, to a display apparatus for forming a storage capacitor by a gate wiring.

In a liquid crystal display (LCD) or an organic light emitting diode (OLED) display, a thin film transistor substrate (TFT) is used as a circuit board for driving each pixel independently.

The thin film transistor substrate has a scan signal line or gate line for transmitting a scan signal and a signal line or data line for transferring a data signal. The substrate includes a thin film transistor connected to a gate line and a data line, a pixel electrode connected to the thin film transistor, and the like. In addition, it generally includes a storage capacitor (Cst) electrode for maintaining a voltage applied to the pixel electrode for one frame.

The storage capacitor electrode is mainly formed through a metal layer overlapping with the pixel electrode, and may have an independent wiring method or a front gate (Cs-on-Gate) method. In the case of the independent wiring method, a separate common wiring is required for the storage capacitance, but in the case of the front gate method, since the gate line of the front end also operates as the storage capacitor electrode, a separate independent common wiring is not required. Therefore, there is an advantage that the aperture ratio is large.

On the other hand, when the storage capacitor is formed through the gate line, the load of the gate wiring is large, which causes a large ripple in the pixel when the gate is turned off, and coupling with the pixel voltage applied to the preceding pixel.

In addition, in the case of the front gate method, since the gate driver for driving the gate line is not directly formed on the thin film transistor substrate due to the resistance of the gate wiring, the gate off signal is not connected between the gate drivers. Gradually the load increases while moving. As a result, the above-described ripple and coupling difference between gate drivers increases, which causes a problem of degrading the quality of the entire display panel.

Accordingly, it is an object of the present invention to provide a display device that reduces the gate off ripple difference between gate drivers.

The object is a plurality of gate lines according to the present invention; A plurality of gate drivers each connected to a different number of gate lines; The display device may include a driving signal unit configured to apply a gate driving signal to any one of the plurality of gate drivers.

The plurality of gate drivers may be arranged in a line, and the gate driving signals applied to one gate driver may be sequentially transmitted to another adjacent gate driver. That is, the present invention is more effective in the method in which one gate driving signal is sequentially transmitted than the method in which the gate on / off signal is applied to each gate line.

In order to reduce the load due to the increasing gate line, the number of the gate lines connected to the gate driver decreases as the gate driver is arranged farther from the driving signal in the direction in which the gate driving signal is transmitted. .

A data line crossing the gate line; A pixel region defined by the gate line and the data line; The display device may further include a storage electrode extending from the gate line to the pixel area.

The thin film transistor may further include a thin film transistor formed at an intersection point of the gate line and the data line, and the gate driving signal may include a gate off signal applied to the thin film transistor. The gate-off signal applied to the thin film transistor should be maintained for one frame, but the present invention is to improve this because ripple occurs because it is not maintained at a constant voltage due to various factors.

On the other hand, the above object, according to the present invention, a plurality of gate lines; Gate drivers connected to different numbers of the gate lines and connected in series with each other; And a driving signal unit connected in series with the gate driver and configured to apply a gate driving signal to the gate driver, wherein a difference in resistance by the gate line in each gate driver is within a predetermined range. Can be.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In various embodiments, like reference numerals refer to like elements, and like reference numerals refer to like elements in the first embodiment and may be omitted in other embodiments.

1 is a schematic diagram of a display apparatus according to an embodiment of the present invention. In the present embodiment, a liquid crystal display device is described as an example of a display device, but the present invention can be applied to an organic light emitting diode (OLED). That is, a display device in which a gate line and a data line are formed and an image is formed by driving the thin film transistor is not limited to the above-described display device type.

As shown in the drawing, the display device according to the present embodiment includes a display area 100 including a display element including a gate line 110 and a data line 120, a gate driver 240, and a data driver 250. The driving signal unit 220, the gray voltage generator 230, and a signal controller 210 for controlling them are included.

The display area 100 includes a plurality of data lines 120 and a gate line 110 and a plurality of pixels connected thereto. Each pixel includes a switching element connected to the data line 120 and the gate line 110, a liquid crystal capacitor Clc, and a storage capacitor Cst connected thereto. The plurality of gate lines 110 extending in the row direction transmit a scan signal or a gate signal, and the plurality of data lines 120 extending in the column direction transmit a data signal corresponding to an image signal. The switching element is a three-terminal element, its control terminal is connected to the gate line 110, the input terminal is connected to the data line 120, the output terminal is one terminal of the liquid crystal capacitor (Clc) and the storage capacitor (Cst) Is connected to.

In the display area 100 having such a structure, when a gate-on voltage is applied to the gate line 110 and the switching element is turned on, the gray voltage supplied to the data line 120 is applied to the pixel electrode through the switching element. Then, an electric field corresponding to the difference between the pixel voltage and the common voltage applied to the pixel electrode is applied to the liquid crystal and light is transmitted at a transmittance corresponding to the intensity of the electric field.

The sustain electrode for the storage accumulation capacitor according to the present embodiment extends from the gate line to the pixel region where the pixel is formed. In other words, the sustain electrode is formed by the shear gate method instead of the independent wiring method, thereby obtaining a high aperture ratio. On the other hand, since the gate line serves as a common electrode to form the pixel electrode and the sustain electrode, there is a high probability of coupling with other adjacent pixel voltages, and a load, that is, resistance due to the gate line increases. Such a resistance forms a ripple difference between the gate lines 110 connected to the gate driver 240, and forms a stripe-like pattern in the display area 100.

Therefore, in order to improve this, the display device according to the present embodiment varies the number of gate lines 110 connected to one gate driver 240. The gate driver 240 may also be referred to as a scan driver. The gate driver 240 is connected to the plurality of gate lines 110 to apply a gate driving signal, which is a combination of a gate on voltage and a gate off voltage, from the driving signal unit 220 to the gate line 110. do.

A plurality of gate lines 110 are connected to one gate driver 240, and a plurality of gate drivers 240 are connected in a line. That is, the gate driver 240 first receiving the gate driving signal from the driving signal unit 220 transfers the gate driving signal to another adjacent gate driver 240. In the case of the gate driving signal transmitted sequentially, in particular, the gate-off voltage in which the constant voltage is to be maintained for one frame, a voltage drop due to a resistance occurs in the process of passing through the gate driver 240, and a difference in voltage drop Causes a ripple difference in the gate off voltage. The difference in the ripple is different for each gate driver 240 and gradually increases in the direction in which the gate driving signal is transmitted. This is because the resistance by the gate line 110 gradually increases in the direction in which the gate driving signal is transmitted.

Therefore, the number of gate lines 110 connected to one gate driver 240 decreases as the gate lines are arranged farther in the direction in which the gate driving signal is transmitted. As shown in FIG. 1, the number of gate lines 110 connected to the first gate driver 240 receiving the gate driving signal from the driving signal unit 220, in other words, the gate line region d1 It is larger than the gate line region d2 connected to another adjacent gate driver 240. In addition, it can be seen that the gate line region d3 connected to the gate driver 240 at the bottom of the display region 100 has the smallest number.

That is, the number of gate lines 110 connected to the gate driver 240 is reduced to offset the resistance of the gate line 110 that increases as the gate driving signal is transmitted. Through this configuration, the difference in resistance due to the gate line 110 generated between each gate driver 240 is within a predetermined range. Here, the predetermined range refers to a range in which the resistance due to the gate line 110 can be determined to be substantially the same.

For example, in the related art, if a display device having a resolution of 1024 x 768 includes three gate drivers 240, the gate lines 110 are equally divided so that 256 gate lines 110 are connected to one gate driver 240. It became. According to the present invention, the division ratio of the gate lines 110 may be adjusted to 12: 8: 7 so that the gate lines 110 may be connected to 341: 228: 199. In addition, in the case of a display device having a resolution of 1280 x 1024, 533: 356: 311 can be connected by dividing into 12: 8: 7.

In the case of four gate drivers 240, the number of gate lines 110 may be divided into 12: 8: 7: 6.5 to connect 367: 245: 214: 199 to 1024, or 1200 to 430: 287: 251. You can also connect each 233. The number of gate lines 110 connected to one gate driver 240 may be changed according to the number and resolution of the gate driver 240, and may be adjusted according to a resistance generated in the gate line 110.

As described above, the driving signal unit 220 generates a gate on voltage Von for turning on the switching element, a gate off voltage Voff for turning off the switching element, a common voltage Vcom, and the like. The driving unit 240 is applied to any one.

The data driver 250, also referred to as a source driver, is connected to a data line of the display area 100 to select a gray voltage from the gray voltage generator 230 and apply a data voltage to the data line.

The signal controller 210 generates a control signal for controlling the operations of the gate driver 240, the data driver 250, and the driving signal unit 220, and outputs corresponding control signals to the gate driver 240 and the data driver. 250 and a supply to the drive signal unit 220.

In the control signal supplied from the signal controller 210 to the gate driver 240, a vertical start signal STV for applying a gate on voltage to the gate line and a gate on voltage sequentially applied to the gate lines 240. There is a vertical clock signal CPV and an enable signal OE for enabling the output of the gate driver 240.

In the control signal supplied from the signal controller 210 to the data driver 250, a horizontal command for inputting the data driver DATA from an external image supply source (for example, a graphic controller) to the data driver 250. The start signal STH, the load signal LOAD for instructing the panel to apply the analog data signal in the data driver 250, and the horizontal clock signal HCLK for data shift in the data driver 250. Etc.

In addition, the signal controller 210 outputs a carry signal to the data driver 250 to control a storage order of the data signal before the external data signal is applied to the data line from the data driver 250.

When the scan signal of the gate driver 240 is sequentially applied from the first gate line G1 to the last gate line Gn by using this configuration, an image of one frame is completed in the display area 100. In this way, the frame is repeated to form an image.

2 is a graph illustrating a waveform of a gate off voltage according to an exemplary embodiment of the present invention. As shown, the gate off voltage, which should appear as a straight line with constant voltage, causes ripples up and down due to the influence of an external electrical signal. The first waveform I is a gate-off voltage of the gate driver 240 connected to the driving signal unit 220, and the second waveform II is a gate driver located far from the driving signal unit 220. 240 is the gate-off voltage. The second waveform II, in which the difference between the first waveform I and the amplitude occurs, is a waveform according to the prior art.

On the other hand, the third waveform (III) is the gate-off voltage of the gate driver 240 located far from the driving signal unit 220 according to the present invention, and the second waveform (II) is changed like the third waveform (III). It can be seen that. The third waveform (III) has almost no difference in amplitude from the first waveform (I), which means that the resistance difference of the gate line 110 hardly occurs. As the gate lines 110 are connected less, the resistance by the gate lines 110 decreases, thereby reducing the ripple. According to the experiment, when about 400 gate lines are reduced to 350, the ripple component of about 0.1 to 0.15V is reduced.

Based on the experimental data, the number of connections of the gate line 110 may be adjusted according to the environment of each display device. By controlling the number of gate lines 110, the resistance difference may be reduced, and thus the ripple difference between the gate drivers 240 may be reduced.

Although some embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that modifications may be made to the embodiment without departing from the spirit or spirit of the invention. . It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

As described above, according to the present invention, a display apparatus for reducing a gate off ripple difference between gate drivers is provided.

Claims (6)

A plurality of gate lines; A plurality of gate drivers each connected to a different number of gate lines; And a driving signal unit for applying a gate driving signal to any one of the plurality of gate driving units. The method of claim 1, And the gate drivers are arranged in a row, and the gate driving signals applied to one gate driver are sequentially transmitted to another adjacent gate driver. The method of claim 2, And the number of the gate lines connected to the gate driver decreases as the gate driver is arranged away from the driving signal in a direction in which the gate driving signal is transmitted. The method of claim 1, A data line crossing the gate line; A pixel region defined by the gate line and the data line; And a sustain electrode extending from the gate line to the pixel area. The method of claim 4, wherein A thin film transistor formed at an intersection point of the gate line and the data line, The gate driving signal includes a gate off signal applied to the thin film transistor. A plurality of gate lines; Gate drivers connected to different numbers of the gate lines and connected in series with each other; A drive signal unit connected in series with the gate driver and configured to apply a gate driving signal to the gate driver; And a difference in resistance caused by the gate line in each of the gate drivers is within a predetermined range.

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