KR101257810B1 - IPS mode LCD and driving method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transverse electric field type liquid crystal display device capable of performing an accurate image representation by improving a liquid crystal response speed.

To this end, the present invention provides a display liquid crystal pixel having a pixel electrode and a common electrode, and a first electrode and a second electrode insulated from the pixel electrode and the common electrode; Provided is a transverse electric field type liquid crystal display device including a non-display liquid crystal pixel having a pixel electrode connected to the first electrode, and a falling start for input of the next image data after a liquid crystal response according to image data input is quick. Because of this, the accurate image representation of the liquid crystal display panel is possible. In addition, it can be sufficiently applied by adding a separate electrode to a conventional TN mode liquid crystal display device as well as a transverse electric field type liquid crystal display device, so that it can be sufficiently utilized as a method to guarantee high quality image quality of the liquid crystal display device.

Description

Transverse electric field liquid crystal display and its driving method {IPS mode LCD and driving method

1 is a view showing a conventional transverse electric field type liquid crystal display device

2 is a state diagram of liquid crystal molecules for explaining the movement of liquid crystal molecules in a liquid crystal pixel of a conventional transverse electric field type liquid crystal display device.

3 is a plan view showing the configuration of a transverse electric field type liquid crystal display device according to the present invention.

4 is a plan view showing a transverse electric field type liquid crystal display device according to the present invention;

5 is a cross-sectional view illustrating an electrode configuration and connection form of the electrode control dummy pixel PN and the display pixel PA in the transverse electric field type liquid crystal display device according to the present invention.

6 is a cross-sectional view for explaining another example of an electrode configuration and connection form of the electrode control dummy pixel PN and the display pixel PA in the transverse electric field type liquid crystal display device according to the present invention.

7 is a signal timing diagram for explaining driving of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention.

8A to 8B are liquid crystal molecular state diagrams showing the activation states of liquid crystal molecules according to the driving of the transverse electric field type liquid crystal display device according to the present invention, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

PE: Pixel electrode CE: Common electrode

D0 ~ Dm: Data line G1 ~ Gn: Gate line

PA: LCD for display PN: Dummy pixel for electrode control

A / A: display area N / A: non-display area

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a transverse electric field type liquid crystal display device for realizing high quality by accurate image representation by improving liquid crystal response speed.

In general, an IPS (In-Plane Switching) mode liquid crystal display is a liquid crystal display having a wide viewing angle developed to solve the problem of narrow viewing angle, which is a major disadvantage of the TN mode liquid crystal display. In the IPS mode (hereinafter, referred to as a transverse electric field) liquid crystal display, the common electrode and the pixel electrode are formed on the same substrate together, and the liquid crystals are driven by a horizontal electric field generated between the electrodes. You will have a larger viewing angle.

FIG. 1 is a diagram illustrating a conventional transverse electric field type liquid crystal display device, which is a region in which a plurality of liquid crystal pixels are formed in a predetermined area on a substrate 10 to display an image. A)), a plurality of data drivers 30 for outputting image data to the display area A / A, and a scan signal for controlling data input to the plurality of liquid crystal pixels. A plurality of gate drivers 40 are mounted in a tape carrier package (TCP) 20 in the form of an integrated circuit (IC) chip and connected to the substrate 10. A plurality of conductive lines are formed in the TCP 20 to enable an electrical circuit connection between the drivers 30 and 40 and the display area A / A.

In this case, the data driver 30 is typically positioned above the substrate 10, and the gate driver 40 is configured to be positioned at the side end of the substrate 10, as shown in an enlarged view. In the drawing, data lines Dm-1, Dm, and Dm + 1 are formed in the vertical direction, and gate lines Gn are formed in the horizontal direction so as to intersect the data lines.

In addition, the liquid crystal pixels for displaying the color corresponding to the data are horizontally arranged in order of red (R), green (G), and blue (B) in parallel with the gate line (Gn).

As described above, since the liquid crystal pixels are arranged horizontally with the gate line Gn forming direction, the pixel electrode PE and the common electrode CE, which are formed in each liquid crystal pixel to form a transverse electric field, are connected to the data line Dm. -1, Dm, Dm + 1) are formed in a direction parallel to or within 45 degrees, and the pixel electrode PE and the common electrode are formed by the pixel electrode PE and the common electrode CE. Rubbing is performed in the direction of data line formation, as shown by the arrow (as necessary, in the opposite direction of the arrow) to indicate a normally black mode that is displayed in black when no electric field is applied to CE). To align the liquid crystal.

FIG. 2 is a state diagram for explaining the movement of liquid crystal molecules in a liquid crystal pixel of a conventional transverse electric field type liquid crystal display device having the configuration and features as described above, and (a) shows an arrangement state of liquid crystal molecules when no electric field is formed. (b) shows the arrangement state of the liquid crystal molecules at the time of electric field formation.

In general, the liquid crystal molecules LC of the liquid crystal pixel have an initial orientation when no electric field is applied to the pixel electrode PE and the common electrode CE (that is, PE = CE = 0V) as shown in FIG. Maintain the arrangement in the direction.

In the initial state, when an electric field is formed by applying a voltage between the pixel electrode PE and the common electrode CE (for example, PE = 7V and CE = 0V), as shown in FIG. In addition, the liquid crystal molecules LC rotate in the electric field direction formed by the pixel electrode PE and the common electrode CE, and the light transmittance is changed in proportion to the magnitude of the applied electric field. The alignment of the liquid crystal molecules LC is changed. This is called rising.

  Thereafter, when the electric field formed between the pixel electrode PE and the common electrode CE disappears, the liquid crystal molecules LC are rearranged to the initial state as shown in FIG. 2A. falling).

Of course, the above-mentioned rising and falling of the liquid crystal molecules LC is a characteristic common to all liquid crystal display devices as well as the IPS mode liquid crystal display device.

At this time, the liquid crystal molecules LC rotate faster than the magnitude of the applied electric field when the rising starts due to the formation of the electric field, but the movement of the liquid crystal molecules LC rises simultaneously with the falling phase after the electric field disappears. (rising) Very slow compared to maneuver This is because the liquid crystal molecules LC are rapidly rotated by the electric field during the rising operation, but only depending on the properties of the liquid crystal and the alignment layer (e.g., elastic modulus, rotational viscosity, alignment force, etc.) during the falling operation. This is because liquid crystal molecules are activated.

As such, the slow falling start of the liquid crystal molecules LC results in an incorrect arrangement of the liquid crystal molecules in displaying the next frame. As a result, the image to be displayed cannot be clearly displayed, thereby degrading the quality of the image.

An object of the present invention is to provide a liquid crystal display device having high quality image quality by quickly inducing the activation of liquid crystal molecules during formation and non-formation of an electric field.

In order to achieve the above object, the present invention provides a display liquid crystal pixel comprising a pixel electrode and a common electrode, and a first electrode and a second electrode insulated from the pixel electrode and the common electrode; A transverse electric field liquid crystal display device including a non-display liquid crystal pixel having a pixel electrode connected to the first electrode is provided.

The first electrode and the second electrode may be formed to extend in a direction crossing all of the pixel electrode and the common electrode, respectively.

The first electrode and the second electrode are both formed on the pixel electrode and the common electrode.

The first electrode and the second electrode may be formed on the same layer or on different layers in the array layer of the display liquid crystal pixel.

The first electrode and the second electrode may be formed on the same substrate or on different substrates.

It further comprises a liquid crystal formed on top of the first electrode and the second electrode or between the first electrode and the second electrode.

The first electrode and the second electrode is characterized in that the transparent conductive material or a metal material.

The common electrode and the second electrode of the display liquid crystal pixel are connected to each other.

The common electrode and the second electrode of the display liquid crystal pixel may be formed of the same material.

The display liquid crystal pixel and the non-display liquid crystal pixel may each include a data line and a scan line, and include a thin film transistor connected to the data line and the scan line.

In addition, the present invention is a driving method of a transverse electric field type liquid crystal display device having the above-described characteristics,

Applying a first voltage to a pixel electrode of the display liquid crystal pixel for a first time and applying a second voltage to the common electrode and the second electrode of the display liquid crystal pixel; And applying a reset voltage to the first electrode through the non-display liquid crystal pixel for a second time period, and applying the second voltage to the common electrode and the second electrode of the display liquid crystal pixel. It provides a method of driving a device.

The method may further include applying a third voltage to the first electrode of the display liquid crystal pixel for the first time.

The first voltage is an image data voltage, and the second voltage is a common voltage.

The second voltage and the third voltage are both 0V.

The reset voltage is characterized in that the voltage between 5V ~ 50V.

It is characterized by forming one frame time including the first time and the second time.

The second time may be a time between 1/20 and 1/2 of the one frame time.

And applying a fourth voltage to the pixel electrode of the display liquid crystal pixel for the second time.

The fourth voltage is 0V.

Each of the above steps is repeated every frame.

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

3 is a plan view showing a pixel configuration of a transverse electric field type liquid crystal display device according to the present invention, in which only a configuration form of an electrode formed in the liquid crystal display panel is shown in plan view.

SUMMARY OF THE INVENTION The present invention aims to promptly induce liquid crystal molecules during formation and non-forming of an electric field by a pixel electrode and a common electrode in a transverse electric field type liquid crystal display device. In addition to the electrode CE, the first electrode 1E and the second electrode 2E are further formed.

As shown, the pixel electrode PE and the common electrode CE are formed in parallel with each other by a predetermined distance, and are transparent conductive materials in a direction that can cross both the pixel electrode PE and the common electrode CE. For example, the first electrode 1E and the second electrode 2E of ITO or a metal material are formed in parallel with each other. In this case, the first electrode 1E and the second electrode 2E are not connected to the pixel electrode PE and the common electrode CE, and the first electrode 1E and the second electrode 2E are mutually different. It is preferable that the first electrodes 1E are arranged in parallel on both sides of the second electrode 2E for each pixel. In addition, the first electrode 1E and the second electrode 2E may be added to a substrate on which the pixel electrode PE and the common electrode CE are formed, and may be configured in different layers.

The first electrode 1E and the second electrode 2E configured as described above form an electric field in a direction parallel to the liquid crystal alignment direction of the liquid crystal display panel so that a falling start, which is a return start of the liquid crystal, is performed quickly. Although the pixel electrode PE and the common electrode CE shown in FIG. 3 illustrate the zigzag planar electrode as an example, all of the transverse electric field type liquid crystal displays including the conventional IPS mode or the FFS mode are illustrated. Applicable.

The transverse electric field type liquid crystal display device according to the present invention includes the first electrode 1E configured to accelerate the return speed of the liquid crystal molecules in addition to the pixel electrode (PE in FIG. 3) and the common electrode (CE in FIG. 3). The voltage applied to the second electrode 2E to form an electric field is a voltage signal applied to the pixel electrode PE and the common electrode CE, a timing controller (not shown), or a set voltage signal. It is possible to configure and apply a separate circuit that can be applied for a set time for each set period, which will be described below.

4 is a plan view illustrating a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention.

Data lines D0 to Dm, scan lines G1 to Gn, and horizontal lines on the substrate 100 divided into a display area A / A on which an image is displayed and a non-display area N / A on which an image is not displayed. Liquid crystal pixels PA and PN for electric field driving are formed.

Liquid crystal pixels PA formed in the display area A / A (hereinafter referred to as display liquid crystal pixels) and liquid crystal pixels formed in the non-display area N / A (hereinafter referred to as dummy pixel for electrode control). (Representative pixel PN) is formed by further adding the first electrode 1E and the second electrode 2E on the pixel electrode PE and the common electrode CE as described above in FIG. The first electrode 1E and the second electrode 2E are formed to extend in a direction parallel to the scan lines G1 to Gn.

In addition, the pixel electrode of the electrode control dummy pixel (representative pixel PN) is configured to be connected to the upper first electrode 1E to apply a reset voltage at a predetermined timing, and the second electrode 2E is used for the electrode control. The common electrode CE of the dummy pixel PN or the common electrode CE of each display liquid crystal pixel is connected to receive the common voltage Vcom to form an electric field with the first electrode 1E. .

In addition, in order to drive the liquid crystal pixels PA and PN formed in the display area A / A and the non-display area N / A, data lines from D1 to Dm are allocated to the display area A / A. The data line of D0 is allocated to the non-display area N / A. In this case, an image data voltage is applied to the data lines D1 to Dm configured in the display area A / A, and the display area A / is applied to the data line D0 configured in the non-display area N / A. A voltage (hereinafter referred to as a reset voltage) to be applied to the first electrode (1E of FIG. 3) formed in liquid crystal pixel PA of A) is applied.

FIG. 5 is a cross-sectional view illustrating an electrode configuration and a connection form of the electrode control dummy pixel PN and the display liquid crystal pixel PA in the transverse electric field type liquid crystal display device. FIG. It is shown briefly on the basis of P21).

Referring to FIG. 5, the first substrate 110 having the TFT array, the pixel electrode PE and the common electrode CE, and the second substrate 120 including the color filter (not shown) are liquid crystals. It is spaced apart with (LC) in between.

A separate insulating film 112 is formed on the pixel electrode PE and the common electrode CE, and a first electrode (1E of FIG. 3) and a second electrode (2E of FIG. 3) are formed on the insulating film 112. To form. In the drawing, the first electrode 1E and the second electrode 2E are formed on the same layer so that only the first electrode 1E is displayed, but the first electrode 1E and the second electrode 2E are on different layers. It may be configured to be formed.

In this case, the pixel electrode 114 of the electrode control dummy pixel P01 is configured to be connected to the first electrode 1E so that the voltage applied to the pixel electrode 114 of the electrode control dummy pixel P01 is the first electrode. It is applied to 1E to form an electric field with the second electrode 2E. Although not shown, the second electrode 2E is connected to the common electrode CE of the liquid crystal pixels P11 and P21 or the common electrode (not shown) of the dummy pixel P01 for electrode control. It is configured to maintain the same potential as the electrode CE.

6 illustrates another embodiment of a transverse electric field liquid crystal display device according to an embodiment of the present invention, in which a vertical electric field method (VA, TN, ECB, OCB, etc.) is combined with a transverse electric field method (IPS, FFS, etc.). As a cross-sectional view for explaining the electrode configuration and the connection form of, also briefly shown on the basis of the cross section between AB in FIG.

In the illustrated liquid crystal display, the second electrode 2E serving as the common electrode is insulated from the lower portion of the transverse electric field type liquid crystal pixels P01, P11, and P21 formed on the first substrate 110, and the second substrate ( The first electrode 1E is formed on the 120, and each of the display liquid crystal pixels P11 and P21 operates in the conventional transverse electric field method and also has the first electrode 1E and the second electrode 2E. It also has a feature that it is operated in a vertical electric field method by a vertical electric field formed by).

In such a liquid crystal display device, a liquid crystal (LC _P ) having positive dielectric anisotropy is injected and used, and the first electrode 1E and the second electrode when the liquid crystal molecules fall after the transverse electric field operation is performed. Forming an electric field between (2E) can add the effect of accelerating the falling speed of the liquid crystal molecules.

The driving method of accelerating the falling speed of the liquid crystal molecules by forming an electric field on the first electrode 1E and the second electrode 2E through the configuration of the electrode control dummy pixel PN is shown in FIGS. A detailed description will be given with reference to the signal timing diagram of 7 and the liquid crystal molecular state diagram of FIGS. 8A to 8C.

The signal timing diagram of FIG. 7 shows the voltage applied to each electrode when the first and second image data capable of displaying an arbitrary color are sequentially input to an arbitrary liquid crystal pixel (eg, P11 of FIG. 4). 8A through 8C illustrate the first image data input, reset driving, and second image data input in the transverse electric field type liquid crystal display device of the normally black mode, respectively. The state of a liquid crystal molecule is illustrated.

In other words, a first image data voltage capable of displaying an arbitrary color is applied to the liquid crystal pixel P11 in the display area A / A having the electrode configuration of FIG. 3 described above in the nth frame. For example, in response to a scan signal input to the scan line G1 using a white data voltage (for example, 7V) for displaying a white color as the first image data, the pixel electrode PE is connected to the pixel electrode PE through the data line D1. The common voltage CE is applied to the common electrode CE. Accordingly, an electric field is formed between the pixel electrode PE and the common electrode CE of the liquid crystal pixel P11 so that the liquid crystal molecules LC rotate as shown in FIG. 8A in the initial arrangement state to display a white color.

Thereafter, a reset period is provided. In this case, an electric field is formed between the first electrode 1E and the second electrode 2E as a period for driving to quickly return the liquid crystal molecules in the state of FIG. 8A to the original state. Step.

That is, a separate scan signal is applied to the pixel electrode PE and the common electrode CE of the liquid crystal pixel P11 to which the first image data voltage is input in the same frame section to remove an electric field, and the separate scan signal. 0V is input to the pixel electrode PE, and a reset voltage is applied to the dummy pixel P01 through the data line D0.

The reset voltage applied to the electrode control dummy pixel P01 is applied to the first electrode 1E electrically connected to form an electric field separate from the second electrode 2E. Of course, the second electrode 2E formed on the liquid crystal pixel P11 of the display area A / A is connected to the common electrode CE to continuously apply 0V.

At this time, the reset voltage is preferably selected between 5V and 50V, but in this embodiment, 10V is applied to the first electrode 1E and 0V, which is a common voltage, is applied to the second electrode 2E.

An electric field is formed between the first electrode 1E and the second electrode 2E by the applied reset voltage, and the liquid crystal molecules LC quickly return to the state of FIG. 8B from the state of FIG. 8A. .

In this case, the reset period may allocate a time between 1/20 and 1/2 of the time when the liquid crystal display panel displays one frame, which is adjusted according to the properties of the liquid crystal and the alignment layer.

When the liquid crystal molecules LC quickly return to the initial arrangement as shown in FIG. 8B by the electric field applied to the first electrode 1E and the second electrode 2E, the second image is input at the next n + 1 th frame. There is an advantage that it is possible to quickly and accurately implement the image representation by the data voltage (for example, 3V, the liquid crystal molecular state shown in Figure 8c).

Of course, even after the input of the second image data, the liquid crystal molecules LC rotated through the reset section are quickly returned to the initial arrangement as shown in FIG. 8B, and then the next frame is driven.

In addition, while a reset voltage is input to the first electrode 1E and the second electrode 2E, a black data voltage is applied to the pixel electrode PE in the normally black mode to further recover the liquid crystal molecules LC. When the acceleration method is added, the falling start of the liquid crystal molecules LC becomes very rapid.

In the transverse electric field type liquid crystal display device according to the embodiment described above, a falling start for input of the next image data is quickly performed after the liquid crystal response according to the image data input, so that accurate image expression of the liquid crystal display panel is performed. This has a possible advantage. In addition, it can be sufficiently applied by adding a separate electrode to a conventional TN mode liquid crystal display device as well as a transverse electric field type liquid crystal display device, so that it can be sufficiently utilized as a method to guarantee high quality image quality of the liquid crystal display device.

Claims (20)

A display liquid crystal pixel having a pixel electrode and a common electrode, and a first electrode and a second electrode insulated from the pixel electrode and the common electrode; Non-display liquid crystal pixel having a pixel electrode connected to the first electrode Transverse electric field type liquid crystal display device comprising a The method according to claim 1, The first electrode and the second electrode are each formed to extend in a direction crossing both the pixel electrode and the common electrode. The method according to claim 1, Both the first electrode and the second electrode are formed on the pixel electrode and the common electrode. The method according to claim 1 or 2, The first electrode and the second electrode are formed on the same layer or different layers from each other in the array layer of the liquid crystal pixel for display. The method according to claim 1, The first and second electrodes are formed on the same substrate or on different substrates. The method according to claim 1, Liquid crystal formed on the first electrode and the second electrode or between the first electrode and the second electrode Transverse electric field type liquid crystal display device further comprising The method according to claim 1, The first and second electrodes are transverse electric field liquid crystal display, characterized in that the transparent conductive material or a metal material. The method according to claim 1, Transverse field type liquid crystal display device, characterized in that the common electrode of the display liquid crystal pixel and the second electrode are connected to each other. The method according to claim 1, The common electrode and the second electrode of the liquid crystal display pixel are formed of the same material. The method according to claim 1, The display liquid crystal pixels and the non-display liquid crystal pixels each have a data line and a scan line, and have a thin film transistor connected to the data line and the scan line. A display liquid crystal pixel having a pixel electrode and a common electrode, and a first electrode and a second electrode insulated from the pixel electrode and the common electrode; A driving method of a transverse electric field type liquid crystal display device comprising a non-display liquid crystal pixel having a pixel electrode connected to the first electrode, Applying a first voltage to a pixel electrode of the display liquid crystal pixel for a first time and applying a second voltage to the common electrode and the second electrode of the display liquid crystal pixel; Applying a reset voltage to the first electrode through the non-display liquid crystal pixel for a second time and applying the second voltage to the common electrode and the second electrode of the display liquid crystal pixel; Method of driving a transverse electric field type liquid crystal display device comprising a The method of claim 11, Applying a third voltage to the first electrode of the liquid crystal pixel for the first time period Method of driving a transverse electric field type liquid crystal display device further comprising The method of claim 11, And wherein the first voltage is an image data voltage and the second voltage is a common voltage. The method according to claim 11 or 12, The second voltage and the third voltage are both driving method of the transverse electric field type liquid crystal display device, characterized in that 0V. The method of claim 11, The reset voltage is a driving method of a transverse electric field type liquid crystal display device, characterized in that the voltage between 5V ~ 50V The method of claim 11, A method of driving a transverse electric field type liquid crystal display device comprising one frame time including the first time and the second time The method according to claim 16, And wherein the second time is a time between 1/20 and 1/2 of the time of one frame. The method of claim 11, Applying a fourth voltage to the pixel electrode of the display liquid crystal pixel for the second time Method of driving a transverse electric field type liquid crystal display device further comprising The method of claim 18, The fourth voltage is a driving method of a transverse electric field type liquid crystal display device, characterized in that 0V. The method of claim 11, A method of driving a transverse electric field type liquid crystal display device, wherein the steps are repeated every frame.

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