KR20070094188A - Liquid crystal display device - Google Patents

Abstract

An LCD(Liquid Crystal Display) device is provided to enable light to be intercepted in a moment according to the response of liquid crystal additionally formed after additionally forming the liquid crystal in the upper part of a TN(Twist Nematic) mode liquid crystal panel, thereby realizing a natural video. An LCD(Liquid Crystal Display) device comprises the followings: a first liquid crystal panel(10) where pixels are formed in an area at which a gate line and a data line are crossed; a timing control unit(50); a data driver(40) which provides a data signal to the data line of the first liquid crystal panel as data and the data control signal provided from the timing control unit; a gate driver(30); a control unit(60) which controls power for black insertion as a black control signal in a frame period and supplies the power; and a second liquid crystal panel(20) which is composed of being piled on the first liquid crystal panel and performs optical shutter operation for black insertion by the power supplied from the control unit.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is a waveform diagram illustrating an operation of a liquid crystal display device according to gate signals G and GB.

2 is a partial cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

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

4 is a waveform diagram illustrating a black insertion operation of a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a partial cross-sectional view of the glass substrate 26 further formed in the liquid crystal display according to the exemplary embodiment of the present invention.

The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display capable of black insertion for a certain period within a frame.

BACKGROUND ART Liquid crystal display devices, which have recently been in the spotlight as flat panel displays, have been actively studied due to their high contrast ratio, suitable for gradation display and moving image display, and low power consumption.

In particular, it can be manufactured with a thin thickness, so it can be used as an ultra-thin display device such as a wall-mounted TV in the future, and it is used as a display of a battery-operated notebook computer because it is light in weight and consumes much less power than a CRT CRT. It is attracting attention as a display device. In addition, since it is manufactured as a small panel and used as a mobile phone display, its use is various.

Such a liquid crystal display has a variety of different modes depending on the nature of the liquid crystal and the structure of the pattern.

Specifically, TN mode (Twist Nematic Mode) for arranging the liquid crystal directors to be twisted by 90 ° and then applying a voltage to control the liquid crystal directors, and by dividing one pixel into several domains, a wide viewing angle is realized by changing the main viewing angle direction of each domain. Multi-domain mode, OCB mode (Optical Compensated Bend Mode), which compensates the phase change of light according to the direction of light by attaching a compensation film to the outer peripheral surface of the substrate, and forms two electrodes on one substrate. In-plane switching mode in which the directors of the liquid crystal are twisted in the parallel plane of the alignment layer, and VA mode (Vertical Alignment) in which the long axis of the liquid crystal molecules is vertically aligned with the alignment layer plane by using a negative liquid crystal and a vertical alignment layer. Mode).

Among the liquid crystal display devices, the TN mode liquid crystal display device may have blurring or tailing due to a limitation in response speed. Here, brushing refers to a phenomenon in which an afterimage remains when the screen passes rapidly, and tailing refers to a phenomenon in which the image sags like a tail.

As an example to solve this problem, as shown in FIG. 1, a technique of inserting black for a predetermined period in one frame may be used. That is, in FIG. 1, one frame is applied to an operation period A that operates in response to a gate signal G applied for a specific gray level except for black, and a gate signal GB applied for black gray. After dividing by the blink section B which operates in response, the black may be expressed during the blink section B to prevent the occurrence of brushing or tailing.

However, the TN mode liquid crystal display has a problem in that it is difficult to implement both of these periods A and B during one frame due to the limitation of the response time.

Therefore, in the related art, black is implemented in the blink section after the blink section is separately set in addition to the section displayed for 1H using a liquid crystal display having a high response speed as in the OCB mode.

However, a liquid crystal display device having a high response speed such as the OCB mode has to implement black separately by applying a gate pulse signal twice during 1H, and there is a problem in that a driver IC needs to be developed.

In addition, the OCB mode liquid crystal display requires a high voltage to transition from the initial region to the driving region, and has a large power consumption since it is driven twice during 1H.

At this time, the initial region is an unusable region in a disordered state, and when a voltage greater than a critical voltage (about 1.5V to 2V) is applied, the initial region is actually transitioned to a driving region where we can drive a signal.

In the driving region, when driven below the threshold voltage, it is necessary to maintain a constant voltage above the threshold voltage at all times because of the nature of returning to the initial region. In addition, when the transition from the initial region to the driving region usually takes a considerable time, since a high voltage is usually applied to reduce this time, there is a large power consumption problem.

In order to solve this problem, the conventional liquid crystal display uses a technique of inserting black by turning off the backlight for a predetermined period in one frame.

However, such a technology using the backlight has a large power consumption due to the on / off of the backlight, there is a problem such as a decrease in brightness due to the frequent on / off of the backlight.

Accordingly, an object of the present invention is to further form a liquid crystal layer and an electrode on the upper substrate of the TN mode liquid crystal display, and then insert a black section in one frame as the liquid crystal molecules of the added liquid crystal layer react, thereby reducing power consumption. Black inserts without the need for additional driver IC development.

A liquid crystal display device for achieving the above object includes a first liquid crystal panel in which pixels are formed in an area where a gate line and a data line cross each other; A timing controller configured to receive data, a vertical synchronization signal, a horizontal synchronization signal, a clock signal, and a control signal from an external source and output data, a data control signal, a gate control signal, and a black control signal; A data driver for providing a data signal to a data line of the first liquid crystal panel using the data and data control signals provided by the timing controller; A gate driver providing a gate signal to a gate line of the first liquid crystal panel using a gate control signal provided from the timing controller; A controller which controls and provides power for black insertion at one frame period as the black control signal; And a second liquid crystal panel configured to overlap with the first liquid crystal panel and performing an optical shutter operation for black insertion by a power source provided from the controller.

In the above configuration, it is preferable that the controller shifts the vertical synchronizing signal to a predetermined section within one frame, and applies power to the second liquid crystal panel synchronized with the shifted vertical synchronizing signal.

In the above configuration, the control unit preferably shifts the shifted vertical synchronization signal to be enabled between a period after all of the gate pulse signals are applied to the gate line and before the next frame starts.

In the above configuration, it is preferable that the second liquid crystal panel is formed on the first liquid crystal panel.

In the above configuration, the second liquid crystal panel may include: a first electrode formed on the first liquid crystal panel and receiving power from the controller; A substrate spaced apart from the first liquid crystal panel by a predetermined distance; A second electrode formed under the substrate and receiving power from the controller; A liquid crystal filled between the first liquid crystal panel and the substrate; And a polarizing plate attached to an upper portion of the substrate.

In the above configuration, it is preferable that the second liquid crystal panel inserts black by reacting the liquid crystal by a power supplied from the control unit.

In the above configuration, the liquid crystal preferably has a molecular arrangement of the TN mode.

In the above configuration, the first and second electrodes are preferably formed of a transparent conductive metal.

In the above configuration, the second liquid crystal panel may include a first substrate attached to an upper portion of the first liquid crystal panel; A first electrode formed on the first substrate and receiving power from the controller; A second substrate spaced apart from the first substrate by a predetermined distance; A second electrode formed under the second substrate and receiving power from the controller; A liquid crystal filled between the first substrate and the second substrate; And a polarizing plate attached to an upper portion of the second substrate.

In the above configuration, it is preferable that the second liquid crystal panel inserts black by reacting the liquid crystal by a power supplied from the controller.

In the above configuration, the liquid crystal preferably has a molecular arrangement of the TN mode.

In the above configuration, the first and second electrodes are preferably formed of a transparent conductive metal.

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

The structure of FIG. 2 is disclosed as an embodiment of the present invention. In the embodiment of FIG. 2, one substrate 22 is added to the upper substrate 13 of the TN mode liquid crystal panel 10 by a predetermined interval, and the upper portion is The liquid crystal panel 20 is additionally formed by injecting the liquid crystal 24 between the substrate 13 and the added substrate 30, thereby controlling black insertion according to the on / off state of the liquid crystal 24.

Specifically, in the embodiment of FIG. 2, the lower substrate 11, the common electrode 14, etc., in which the thin film transistor TFT, the pixel electrode 12, and the like are formed in each pixel area defined by the intersection of the gate line and the data line, may be used. The liquid crystal 15 is injected between the upper substrate 13 to be formed, and the TN mode liquid crystal panel 10 having polarizers 16 and 17 attached to the lower portion of the lower substrate 11 and the upper portion of the upper substrate 13, respectively. It is provided.

In addition, the glass substrate 22 is positioned to be spaced apart from the TN mode liquid crystal panel 10 by a predetermined interval, and when the glass substrate 22 and the polarizer 17 face each other, ITO (Indium Tin Oxide) and IZO (Indium) are respectively disposed on the side surfaces thereof. Electrodes 21 and 23 are formed by depositing a transparent conductive metal having excellent light transmittance such as zinc oxide.

Thereafter, the liquid crystal 24 is injected between the glass substrate 22 and the polarizing plate 17, and then the polarizing plate 25 is attached to the upper portion of the glass substrate 22 to form the liquid crystal panel 20. At this time, the voltage VEXT is selectively applied to the electrodes 21 and 23 from the outside, and the direction in which the light of the polarizing plate 17 and the polarizing plate 25 passes, that is, the polarization axis has a 90 degree phase difference.

In the liquid crystal panel 10 of the liquid crystal display device formed as described above, gate voltages are sequentially applied to the gate lines for one frame, and the thin film transistors are sequentially turned on for each gate line by the gate voltage. At this time, the data voltage is simultaneously applied to the liquid crystal cell through each turned-on thin film transistor.

Due to the data voltage, the molecules of the liquid crystal 15 of the TN mode liquid crystal panel 10 react, and the light incident from the backlight (not shown) passes through the polarizer 17 through the lower portion.

Thereafter, the light passing through the polarizing plate 17 passes through the liquid crystal 24 formed on the polarizing plate 17, and then passes through the polarizing plate 25 formed on the glass substrate 22 to form an image on the screen. . At this time, molecules are aligned in the liquid crystal 24 in the same manner as in the TN mode, and since the voltage VEXT is not applied from the outside, light passes through the liquid crystal 24.

When the black insertion point corresponds to the black insertion point in one frame period, the predetermined voltage VEXT is applied to the electrodes 21 and 23, and the liquid crystal 24 is controlled by the voltage difference between the electrodes 21 and 23 according to the voltage VEXT. By reacting and rearranging the molecules, light passing through the polarizer 17 is blocked by the liquid crystal 24 and the polarizer 25.

That is, in the embodiment of the present invention, black insertion is possible by applying the external voltage VEXT to the electrodes 21 and 23 of the liquid crystal panel 20, which will be described in detail with reference to FIGS. 3 and 4. same.

First, as shown in FIG. 3, the gate driver 30, the data driver 40, the timing controller 50, and the like are electrically connected to the liquid crystal panel 10 in the liquid crystal display after the liquid crystal cell process. The controller 60 for controlling the insertion is electrically connected to the added liquid crystal panel 20.

Here, the gate driver 30 is connected to the gate lines G ₁ to G _m of the liquid crystal panel 10 to receive a gate pulse signal formed of a combination of the gate on voltage VON and the gate off voltage VOFF. It is applied to (G ₁ ~ G _n ).

The data driver 40 is connected to the data lines D ₁ to D _m of the liquid crystal panel 10 to apply the gray voltage applied by the gray voltage generator (not shown) as a data signal.

The timing controller 50 generates control signals CON1 and CON2 for controlling operations of the gate driver 30 and the data driver 40, and outputs control signals CON1 and CON2 corresponding to the respective parts. 30 to the data driver 40.

The controller 60 provides the external voltage VEXT to the liquid crystal panel 20 using the vertical synchronization signal VSYNC.

In the liquid crystal display device having such a configuration, the timing controller 50 displays the RGB image signals R, G and B and the RGB image signals R, G and B from an external graphic controller (not shown). A control signal to control, for example, a vertical synchronization signal VSYNC, a horizontal synchronization signal HSYNC, a main clock MCLK, a data enable signal DE, and the like are provided.

In addition, the timing controller 50 generates the gate control signal CONT1 and the data control signal CONT2 through the control signals provided as described above, and operates the image signals R, G, and B in the liquid crystal panel 10. Process according to the conditions.

Thereafter, the timing controller 50 sends the gate control signal CONT1 to the gate driver 30, and transmits the data control signal CONT2 and the processed image signals R ', G', and B 'to the data driver 40. Export to).

Here, the gate control signal CONT1 is an output signal defining the width of the gate pulse signal and the vertical and horizontal synchronization start signals indicating the start of the output of the gate pulse signal, the gate clock signal controlling the timing of the output of the gate pulse signal, and the width of the gate pulse signal. Includes an Able traffic light.

In addition, the data control signal CONT2 indicates the horizontal synchronization start signal indicating the start of input of the image data R ', G', and B 'and the application of the corresponding data signal to the data lines D ₁ to D _m . A load signal, an inversion signal for inverting an electrode of the data signal with respect to the common voltage VCOM, a data clock signal, and the like.

In accordance with the data control signal (CONT1) is at such a timing controller 50, the gate driver 30 has a gate line to apply a gate-on voltage (VON) to the gate line _{(G 1 ~ G n) (} G 1 ~ When the thin film transistor Q connected to G _n is turned on, the data signal applied to the data lines D ₁ to D _m is applied to the corresponding pixel through the turned on thin film transistor Q.

In addition, according to the data control signal CONT2 applied by the timing controller 50, the data driver 40 sequentially receives and shifts the image data R ′, G ′, and B ′ corresponding to one pixel of the row. . The data driver 40 selects a gray voltage corresponding to each of the image data R ', G', and B 'among the gray voltages applied by the gray voltage generator, and then the image data R', G ', B. ') Is converted into a corresponding data signal and applied to the corresponding data lines D ₁ to D _m .

Thereafter, the difference between the data signal applied to the pixel and the common voltage VCOM is represented as a charging voltage, that is, a pixel voltage. Here, the arrangement of the liquid crystal molecules varies according to the magnitude of the pixel voltage, and accordingly, the polarization of light passing through the liquid crystal layer changes. This change in polarization is represented by a change in transmittance of light by a polarizer (not shown) attached to the liquid crystal panel 10.

Then, after one horizontal period (or "1H") (one period of the horizontal synchronization signal HSYNC, the data enable signal DE, and the gate clock CPV), the gate driver 30 and the data driver 40 are passed. Repeats the same operation for the pixels in the next row.

In this manner, the liquid crystal display according to the exemplary embodiment of the present invention applies the data signal to all the pixels by sequentially applying the gate pulse signals to all the gate lines G ₁ to G _n during one frame.

Thereafter, the controller 60 shifts the vertical synchronizing signal VSYNC as shown in FIG. 3, and the external voltage VEXT is synchronized with the shifted vertical synchronizing signal VSYNC_SHIFT so that the liquid crystal panel ( 20) is applied to the electrode.

That is, after the gate pulse signals are applied to all the gate lines G ₁ to G _n , the controller 60 controls the external voltage VEXT in a section before the next frame, that is, before the vertical sync signal VSYNC is enabled again. It is preferable to shift the vertical synchronizing signal VSYNC to be applied to the electrode of the liquid crystal panel 20.

As the external voltage VEXT is applied to the electrodes of the liquid crystal panel 20 by the shifted vertical synchronization signal VSYNC_SHIFT, the liquid crystals of the liquid crystal panel 20 react to express black.

At this time, the liquid crystal of the added liquid crystal panel 20 is formed in the TN mode in order not to change the process, and thus has a slow liquid crystal reaction rate. That is, when the brightness BR of the light passing through the polarizing plate is in the gray state, the brightness BR of the light passing through the liquid crystal is changed from gray to black, and then in black. It goes through the steps of turning to gray.

However, since the liquid crystal only serves to pass or block the light by the voltage VEXT selectively applied from the outside, the change of the brightness BR has nothing to do with the screen operated by the liquid crystal.

As described above, in the exemplary embodiment of the present invention, the liquid crystal and the polarizing plate are additionally formed on the existing TN mode liquid crystal panel, thereby allowing black to be inserted within a frame for a predetermined time.

That is, the liquid crystal is injected between the TN mode liquid crystal panel and the additionally formed glass substrate, and black is inserted in a frame for a certain period by the reaction of the liquid crystal. Therefore, the embodiment of the present invention has the effect that natural video can be implemented without inserting black or tailing by inserting black in a frame for a predetermined period.

In addition, since the embodiment of the present invention applies an external voltage VEXT to the electrode to which the liquid crystal of the added liquid crystal device reacts, it is lower than the voltage necessary to transition from the initial region to the driving region of the OCB mode liquid crystal. It has a favorable effect on the side.

In addition, the embodiment of the present invention by controlling the transmission of light by the additionally formed liquid crystal, there is an effect that it is not necessary to further develop the existing driver IC for black insertion.

Although the structure as shown in FIG. 2 is shown as an embodiment of the present invention, the present invention is not limited thereto, and black insertion may be performed by additionally installing a glass substrate on which a transparent conductive metal is deposited on the polarizer 17.

Specifically, as shown in FIG. 4, the glass substrate 26 is mounted on the polarizer 17 provided in the TN mode liquid crystal panel 10, and a transparent conductive metal is deposited on the glass substrate 26. The glass substrate 22 is positioned to be spaced apart from the glass substrate 26 by a predetermined distance, and a transparent conductive metal is deposited on the lower portion of the glass substrate 22.

Thereafter, the liquid crystal 24 is injected between the glass substrate 26 and the glass substrate 22, and then the polarizing plate 25 is attached to the upper portion of the glass substrate 22, whereby the liquid crystal due to the external voltage VEXT is applied. The reaction of (24) determines whether black is inserted.

As described above, after the liquid crystal is additionally formed on the TN mode liquid crystal panel, light is momentarily blocked according to the reaction of the additionally formed liquid crystal, thereby enabling natural video to be realized.

In addition, since the voltage VEXT applied to the electrode is lower than the voltage required to transition from the initial region to the driving region of the OCB mode liquid crystal, there is a favorable effect in terms of power consumption.

In addition, the present invention is effective to control the transmission of light by the liquid crystal additionally formed on the TN mode liquid crystal panel, there is an effect that there is no need to further develop the existing driver IC for black insertion.

While the invention has been shown and described with reference to specific embodiments, the invention is not limited thereto, and the invention is not limited to the scope of the invention as defined by the following claims. Those skilled in the art will readily appreciate that modifications and variations can be made.

Claims (12)

A first liquid crystal panel in which pixels are formed in an area where the gate line and the data line cross each other; A timing controller configured to receive data, a vertical synchronization signal, a horizontal synchronization signal, a clock signal, and a control signal from an external source and output data, a data control signal, a gate control signal, and a black control signal; A data driver for providing a data signal to a data line of the first liquid crystal panel using the data and data control signals provided by the timing controller; A gate driver providing a gate signal to a gate line of the first liquid crystal panel using a gate control signal provided from the timing controller; A controller which controls and provides power for black insertion at one frame period as the black control signal; And And a second liquid crystal panel configured to overlap with the first liquid crystal panel and to perform an optical shutter operation for black insertion by a power source provided from the control unit. The method of claim 1, And the control unit shifts the vertical synchronizing signal to a predetermined section within one frame, and applies the power synchronized with the shifted vertical synchronizing signal to the second liquid crystal panel. The method of claim 2, And the control unit shifts the shifted vertical synchronization signal to be enabled between a period after all of the gate pulse signals are applied to the gate line and before the next frame starts. The method of claim 1, And a second liquid crystal panel formed on the first liquid crystal panel. The method of claim 4, wherein The second liquid crystal panel, A first electrode formed on the first liquid crystal panel and receiving power from the controller; A substrate spaced apart from the first liquid crystal panel by a predetermined distance; A second electrode formed under the substrate and receiving power from the controller; A liquid crystal filled between the first liquid crystal panel and the substrate; And And a polarizer attached to an upper portion of the substrate. The method of claim 5, And wherein the second liquid crystal panel inserts black by reacting the liquid crystal by a power supplied from the controller. The method of claim 5, And the liquid crystal has a molecular arrangement in TN mode. The method of claim 5, And the first and second electrodes are formed of a transparent conductive metal. The method of claim 4, wherein The second liquid crystal panel, A first substrate attached to an upper portion of the first liquid crystal panel; A first electrode formed on the first substrate and receiving power from the controller; A second substrate spaced apart from the first substrate by a predetermined distance; A second electrode formed under the second substrate and receiving power from the controller; A liquid crystal filled between the first substrate and the second substrate; And And a polarizing plate attached to an upper portion of the second substrate. The method of claim 9, And wherein the second liquid crystal panel inserts black by reacting the liquid crystal by a power supplied from the controller. The method of claim 9, And the liquid crystal has a molecular arrangement in TN mode. The method of claim 9, And the first and second electrodes are formed of a transparent conductive metal.

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