KR20080061222A - Liquid crystal display device - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to connect adjacent common electrodes toward the gate line direction to individual common electrodes opposite to a gate line and to also connect each display electrode at the data line direction alternately to the data lines at the left and right directions. Data lines(D1,D2,D3) and gate lines(G1,G2,G3) are arranged on an LCD. Common lines(C1,C2) are located oppositely to the gate lines. Pixels defined by the gate lines and data lines are expressed by P(1,1) and P(1,2) according to the positions. The pixel P(1,1) is connected with the left data line and the pixel P(1,2) is connected with the right data line. Common lines opposite to the gate lines are arranged individually. The common line connects the pixels corresponding to the pixel number of one line with a line by a zigzag type in the upper and lower pixels. The common lines corresponding to the plus driving and the minus driving are arranged individually so that the amplitude of the data voltage is inhibited low.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is an equivalent circuit diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a diagram showing the voltage waveform of each electrode when the IPS liquid crystal is driven by HV inversion according to the embodiment of the present invention.

3 is a table summarizing comparative data of a liquid crystal display according to an exemplary embodiment of the present invention and a conventional liquid crystal display.

4 is another equivalent circuit diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a timing chart of a driving voltage corresponding to the equivalent circuit of FIG. 4 according to an exemplary embodiment of the present invention.

6 is a conceptual diagram of a conventional HV inversion driving method.

7 is an equivalent circuit diagram of a conventional liquid crystal display.

Fig. 8 is a diagram showing voltage waveforms of the electrodes in the case of HV inversion driving of a conventional IPS liquid crystal.

9 is a graph showing Id-Vg characteristics of TFTs.

<Explanation of Signs of Major Parts of Drawings>

D1, D2, D3: data lines

G1, G2, G3: Gate Line

C1, C2: individual common line

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of reducing the bias voltage of a TFT in an IPS liquid crystal.

IPS liquid crystal has a higher driving voltage than TN liquid crystal. In order to increase the aperture ratio, the interval between the comb electrodes must be opened, so that the interval is about 10 占 퐉.

In a normal TN liquid crystal, when a substrate of about 5 μm is placed horizontally, the liquid crystal is interposed between upper and lower flat plate ITO electrodes. In response to the electric field, when the voltage is V and the gap is d, an electric field of V / d is applied to the liquid crystal. On the other hand, in the IPS liquid crystal, a transverse electric field is used, and when d is the electrode gap, the electric field is smaller than V / d. As a result, the drive voltage of an IPS liquid crystal becomes high compared with TN.

In addition, since the liquid crystal deteriorates when AC is not driven, inversion driving is performed in which a positive voltage and a negative voltage are alternately driven. Specifically, the government voltage is alternately applied every 16 msec of the frame period of the screen, that is, normal television broadcasting.

For such an IPS type liquid crystal display, a method of reducing power consumption by lowering a driving voltage has been proposed. (For example, Japanese Patent Laid-Open No. 10-31464; hereinafter referred to as "Patent Document 1") In this Patent Document 1, the potential applied to the common line is used for each frame using high and low two values. By inverting, the polarity of the voltage across the positive electrode of the pixel is inverted. As a result, it is possible to suppress the potential variation of the signal output from the driver and to reduce power consumption.

However, the prior art has the following problems.

In Patent Document 1, the conventional liquid crystal display device corresponds to the H common inversion driving, and can reduce the voltage applied to the data line, thereby reducing the voltage of the driver IC and the driving circuit. However, simply inverting the voltage of the government in the frame period is unsatisfactory because the corresponding transmittances of the governments are different. There are many HV inversion driving systems in which IPS liquid crystals are applied with a positive and negative voltage for each pixel.

6 is a conceptual diagram of a conventional HV inversion driving method, and a voltage of a negative region is applied to each of the upper, lower, left, and right pixels. However, in the prior art of Patent Document 1, it cannot cope with V inversion. That is, the technique of patent document 1 cannot be applied as it is to the HV inversion driving method which applies the voltage of the negative region for every one pixel up, down, left, and right.

7 is an equivalent circuit diagram of a conventional liquid crystal display. The common line that binds the telephone line to the HV inversion driving method is a constant voltage. The common voltage is common to all the telephone stations, and the data voltage applied to each pixel is divided into a positive voltage and a negative voltage according to, for example, a checker pattern. For this reason, although it is strong against flicker noise, there exists a problem that power consumption is high because a voltage amplitude is large.

Fig. 8 is a diagram showing the voltage waveform of each electrode in the case of HV inversion driving of the conventional IPS liquid crystal, and illustrates the waveform in the case of displaying the white level in the telephone station. The common voltage represented by the dashed line is constant at the telephone station. In addition, the data voltage indicated by the fine dotted lines is applied with the government replaced for each pixel. That is, in the conventional method, it is necessary to convert the data voltage to the government in one frame and apply it.

For these waveforms, the potential difference Vg between the pixel voltage and the gate voltage and the potential difference Vd between the pixel voltage and the data voltage are as shown in Fig. 8 (Vg1, Vd1), (Vg2, Vd2), (Vg3, Vd3), (Vg4, 4 combinations of Vd4).

9 is a graph showing the Id-Vg characteristics of the TFT. The four combinations shown in FIG. 8 can be plotted on the curve shown in FIG. 9, and the positions corresponding to (Vg1, Vd1) and (Vg3, Vd3) are plotted in FIG. As shown in FIG. 9, when Vds is large, Ids also increases relatively, resulting in an increase in power consumption.

Therefore, as evident from Figs. 8 and 9, how to reduce the driving voltage after adopting the HV inversion driving method with good image quality for the IPS liquid crystal is a big problem.

Accordingly, in order to solve the above problems, the present invention is to provide a liquid crystal display device that can reduce the bias voltage of the TFT in the IPS liquid crystal by the HV inversion driving method.

A liquid crystal display according to an exemplary embodiment of the present invention for achieving the above technical problem has a common electrode and a display electrode for each pixel defined by a gate line and a data line crossing each other, and a potential difference between the common electrode and the display electrode. A liquid crystal display for displaying a desired image in response to the above, wherein the common electrode is configured such that predetermined common electrodes adjacent in the gate line direction are connected to respective common lines facing each of the gate lines, and the display The electrode is configured to connect each display electrode in the data line direction to either the left data line or the right data line of the display electrode in a predetermined order.

The common electrodes cross each other in a zigzag form by using common lines between two common electrodes adjacent to each other in two vertical lines in the gate line direction, and the display electrodes alternately display one display electrode in the data line direction. And a data line on the left side or a data line on the right side.

Each of the data lines is applied with a voltage of positive inversion for each frame, and data voltages having different polarities are applied to adjacent data lines, and each of the individual common lines is for each frame according to the polarity of the voltage applied to the data lines. Two different common voltages are applied.

The two kinds of different common voltages may be generated to be synchronized with the gate signals of the gate lines and applied to corresponding respective common lines.

A liquid crystal display according to an exemplary embodiment of the present invention has a common electrode and a display electrode for each pixel defined by crossing gate lines and data lines, and displays a desired image in response to a potential difference between the common electrode and the display electrode. In the display device, different common voltages are supplied to common electrodes of the pixels adjacent to each other with the data line therebetween.

The display electrodes of the pixels adjacent to each other along the direction of the data line are supplied with data voltages from different data lines, and each of the data lines is adjacent to each other at the same time that a positive inversion voltage is applied to each frame. The data voltages of different polarities are applied to the lines.

The liquid crystal display may further include individual common lines zigzag-shaped along the gate line to supply different common voltages to common electrodes of the adjacent pixels with the data lines interposed therebetween. do.

The polarity of the common voltage supplied to the adjacent common lines is different from each other, and the polarity of the common voltage is inverted in units of frames.

The liquid crystal display further includes a gate driver circuit for supplying a gate signal to each gate line, and a flip-flop circuit, coupled to the gate driver circuit, to supply a common voltage to the individual common line according to the gate signal. Characterized in that the configuration.

The liquid crystal display further comprises a gate driver circuit for supplying a gate signal to each gate line, and a common voltage driver circuit for supplying a common voltage to the individual common lines according to the gate signal. It is done.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

1 is an equivalent circuit diagram of a liquid crystal display according to an exemplary embodiment of the present invention. 1, for convenience of explanation, the data lines will be referred to as D1, D2 and D3 in order from the left, and the gate lines will be referred to as G1, G2 and G3 in order from above.

In addition, common lines facing the gate lines are set to C1 and C2 in order from the top. In addition, the pixels defined by the gate lines and the data lines are assumed to be P (1, 1), P (1, 2), P (2, 1), and P (2, 2) according to their positions.

The liquid crystal display device shown in FIG. 1 is characterized by the following three types. First, the first feature is alternately connecting the drain electrode (Drain) of the TFT corresponding to each pixel arranged in the longitudinal direction to the right and left data lines. Specifically, for the pixels P (1, 1) and P (2, 1) arranged vertically, P (1, 1) is connected to the data line D1 on the left side, and P (2, 1) is the data line on the right side. It is connected to D2.

Next, the second feature is not to make the common voltage common to the telephone station, but to provide a common line facing the gate line separately. Specifically, there are individual common lines facing the gate line, such as common line C1 facing gate line G1 and common line C2 facing gate line G2.

In addition, a third feature is to connect the common lines connected to the pixel electrodes of the respective pixels in a zigzag pattern up and down as shown in FIG. Specifically, the common line C1 corresponds to the number of pixels of one line in a zigzag form of pixels of the upper and lower lines in the order of pixels P (1, 1), P (2, 2), P (1, 3) ... A number of pixels and lines are connected. This zigzag connection corresponds to a connection intersecting in a so-called zigzag form.

According to the structure having such first to third features, at any one gate timing, the + driving data line (corresponding to D1 and D3 in FIG. 1) and the common line corresponding to + driving (C1 in FIG. 1) are provided. Pixels (corresponding to P (1, 1) and P (2, 2) in Fig. 1) can be added with + voltage as the data voltage, and there is no need to perform the inversion in the first frame. .

Similarly, in the pixel (corresponding to P (2, 1) in FIG. 1) at the intersection of the data line to be driven (corresponding to D2 in FIG. 1) and the common line (corresponding to C2 in FIG. 1) corresponding to driving. The voltage can be added, eliminating the need for government inversion within one frame.

In addition, since the common line corresponding to + drive and the common line corresponding to − drive are separately provided, it is possible to suppress the amplitude of the data voltage low. That is, the amplitude of the data voltage can be suppressed by changing the common voltage so as to maintain the potential difference between the common electrode and the display electrode. As a result, the liquid crystal display device having the configuration shown in FIG. 1 can drive the IPS liquid crystal by the HV inversion method, and at the same time, can reduce the bias voltage of the TFT.

2 is a diagram showing the voltage waveform of each electrode in the case of HV inversion driving of the IPS liquid crystal according to the embodiment of the present invention, and when the white level is displayed in a telephone station as shown in FIG. The waveform is illustrated.

The common voltage represented by the dashed line is replaced with two values in synchronization with the gate voltage and becomes a constant value in the frame. In addition, the data voltage represented by the fine dotted line is not applied to the pixel for every pixel, but the same is applied in the same polarity within one frame, and the government is replaced to apply the gate voltage. The amplitude of the data voltage can be kept low by changing the value of the common voltage corresponding to the stationary of the data voltage in the frame period.

For this waveform, the potential difference Vg between the pixel voltage and the gate voltage and the potential difference Vd between the pixel voltage and the data voltage have two combinations of (Vg1, Vd1) and (Vg3, Vd3). As described above, the liquid crystal display device of the present invention has the first to third features, and it is not necessary to switch the data voltage to the government within one frame. It can be changed so that the amplitude of the voltage decreases according to the government.

3 is a graph showing comparative data of a liquid crystal display according to an exemplary embodiment of the present invention and a conventional liquid crystal display. More specifically, the data by the liquid crystal display device of this invention in FIG. 2 is compared with the data by the conventional liquid crystal display device in FIG. In this Fig. 8, for example, the amplitude of each of the peaks of the data voltage is 5V, and the difference between the lowest value of the data voltage and the gate voltage is 2V. In addition, "time" shown in FIG. 8 represents the period in which the voltage is added.

In the liquid crystal display of the present invention, the combination of Vg and Vd is reduced from four to two. As a result, in the past, since one replacement was performed once in one frame, the time when any one voltage was added was 8 ms. However, in the present invention, since it is not necessary to change in one frame, the time when any one voltage is added This increases to 16ms.

Moreover, the value of Vg and Vd can be suppressed smaller than before by the effect of this invention which changes a common voltage. This means that the bias applied to the TFT is small.

As shown in FIG. 2, in the liquid crystal display of the present invention, the conversion of the common voltage can be changed to be synchronized with the gate voltage. Therefore, as shown in FIG. 1, only the flip-flop circuit using the gate signal is configured, so that the converted signal of the common voltage can be easily generated.

4 is another equivalent circuit diagram of a liquid crystal display according to an exemplary embodiment of the present invention. In the equivalent circuit diagram of FIG. 1, the common voltage driver circuit is configured in combination with the gate driver circuit. In the equivalent circuit diagram of FIG. 4, the gate driver circuit is provided separately from the common voltage driver circuit.

5 is a timing chart of a driving voltage corresponding to the equivalent circuit of FIG. 4 in the embodiment of the present invention. The common voltage driver circuit as shown in FIG. 4 is provided separately. When the common side also uses a shift register different from the gate side, a common voltage having a desired waveform can be obtained as shown in FIG. .

In addition, since the gate driver circuit and the common voltage driver circuit have the same circuit configuration, the existing gate driver circuit can be usefully applied to the common voltage driver circuit.

As described above, according to the exemplary embodiment of the present invention, the predetermined common electrodes adjacent in the gate line direction are connected by separate common lines facing the gate line, so that each of the display electrodes in the data line direction is arranged in a predetermined order. It has a configuration of alternately connecting data lines. As a result, a data voltage having the same polarity can be applied within one frame, and two common voltages VcomH and VcomL can be applied in accordance with the polarity of the data voltage, thereby reducing the voltage applied to the TFT. have. As a result, reliability deterioration due to cross talk or bias stress due to leakage of the TFT can be reduced.

In addition, in the above-described embodiment, the case where the connection of the common electrode and the display electrode is connected to each other in a check form as a connection pattern has been described. However, the present invention is not limited to this, but the data to be + driven in any one frame period. The same effect can also be obtained by grouping the pixel to which the line and the common line corresponding to + driving are connected, the data line to be driven and the pixel to which the common line corresponding to driving is connected, and performing predetermined wiring.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention It will be apparent to those skilled in the art.

The liquid crystal display according to the exemplary embodiment of the present invention as described above connects predetermined common electrodes adjacent to each other in the gate line direction to individual common lines facing the gate line, thereby connecting each of the display electrodes in the data line direction in a predetermined order. By alternately connecting the left and right data lines, the bias voltage of the TFT can be reduced with respect to the IPS liquid crystal by the HV inversion driving method.

Claims (14)

A liquid crystal display device having a common electrode and a display electrode for each pixel defined by a gate line and a data line crossing each other, and displaying a desired image in response to a potential difference between the common electrode and the display electrode. The common electrode is configured such that predetermined common electrodes adjacent in the gate line direction are connected to individual common lines facing each of the gate lines, And the display electrode is configured to connect each display electrode in the data line direction to either the left data line or the right data line of the display electrode in a predetermined order. The method of claim 1, The common electrodes cross each other in a zigzag form by using common lines between the common electrodes adjacent to the upper and lower two lines in the gate line direction. And the display electrodes are connected to the data line on the left side or the data line on the right side of each of the display electrodes in the data line direction alternately. The method according to claim 1 or 2, Each of the data lines is applied with a voltage of positive inversion for each frame, and data voltages of different polarities are applied to adjacent data lines. Each of the individual common lines is characterized in that two different common voltages are applied to each frame according to the polarity of the voltage applied to the data line. The method of claim 3, wherein And the two different common voltages are generated in synchronization with the gate signals of the gate lines and applied to corresponding respective common lines. The method of claim 4, wherein A gate driver circuit for supplying a gate signal to each gate line; And a flip-flop circuit, coupled to the gate driver circuit, for supplying a common voltage to the respective common lines in accordance with the gate signal. The method of claim 4, wherein A gate driver circuit for supplying a gate signal to each gate line; And a common voltage driver circuit for supplying a common voltage to the respective common lines in accordance with the gate signal. A liquid crystal display device having a common electrode and a display electrode for each pixel defined by a gate line and a data line crossing each other, and displaying a desired image in response to a potential difference between the common electrode and the display electrode. And a common common voltage supplied to common electrodes of the pixels adjacent to each other with the data line therebetween. The method of claim 7, wherein And the display electrodes of the adjacent pixels along the direction of the data lines are supplied with data voltages from different data lines. The method of claim 8, And a data voltage of different polarity between adjacent data lines is applied to each of the data lines at the same time as the voltage of the inversion is applied to each frame. The method of claim 8, And a common common line formed in a zigzag form along the gate line to supply different common voltages to common electrodes of each of the adjacent pixels with the data lines interposed therebetween. The method of claim 10, And a polarity of the common voltages supplied to the adjacent common lines is different from each other. The method of claim 11, The polarity of the common voltage is inverted in units of frames. The method of claim 11, A gate driver circuit for supplying a gate signal to each gate line; And a flip-flop circuit, coupled to the gate driver circuit, for supplying a common voltage to the respective common lines in accordance with the gate signal. The method of claim 11, A gate driver circuit for supplying a gate signal to each gate line; And a common voltage driver circuit for supplying a common voltage to the respective common lines in accordance with the gate signal.

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