KR100751352B1 - Method for transient driving of optically compensated birefringence liquid crystal display and apparatus thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transition driving method of an OCB liquid crystal display panel capable of initial bend alignment of a liquid crystal within a short time with a low transition driving voltage in a liquid crystal display having an OCB (Optically Compensated Birefringence) mode. In the transition driving method of an OCB liquid crystal display panel according to the present invention, an OCB liquid crystal is formed such that a pixel is formed in a region where a scan line for supplying a scan signal and a data line for supplying a data signal intersect, and a common line passes through the pixel. In an initial starting condition of the display panel, a transition voltage of a pulse waveform whose polarity is inverted with time changes is applied to at least one of the scan line, the data line, and the common line, and the transition voltage is discontinuous. To rise or fall.

Description

Method for transient driving of optically compensated birefringence liquid crystal display and apparatus

1 is a view for explaining the operation of the general OCB mode.

2 is a cross-sectional view schematically illustrating a thin film transistor liquid crystal display panel having a top gate structure as an embodiment to which a transition driving method of an OCB liquid crystal display panel according to the present invention is applied.

FIG. 3 is a circuit diagram schematically illustrating a configuration of the thin film transistor liquid crystal display panel of FIG. 2.

4 is a diagram schematically illustrating a direction in which transition nuclei grow in a thin film transistor liquid crystal display panel having a top gate structure by a transition driving device and a driving method of an OCB liquid crystal display panel according to the present invention.

5 is a waveform diagram schematically showing a transition driving method of an OCB liquid crystal display panel according to another preferred embodiment of the present invention.

6 is a waveform diagram schematically illustrating a transition driving method of an OCB liquid crystal display panel according to another exemplary embodiment of the present invention.

FIG. 7 is a block diagram schematically illustrating a transition driving device of an OCB liquid crystal display panel as a preferred embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

10: OCB liquid crystal display panel, 100: thin film transistor substrate,

121 is a pixel electrode, 122 is a source electrode,

123: drain electrode, 127: gate electrode,

200: common electrode substrate, 221: common electrode,

300: liquid crystal layer, 720: data driver,

730: scan driver, 740: common driver.

The present invention relates to a transition driving method and an apparatus of an OCB liquid crystal display panel, and more particularly, in a liquid crystal display device having an OCB (Optically Compensated Birefringence) mode, the initial bend alignment of the liquid crystal is possible in a short time with low transition driving voltage. A transition driving method of an OCB liquid crystal display panel and an apparatus therefor.

In general, liquid crystal displays (LCDs) are thin, light, emit less electromagnetic waves, and consume less power. Therefore, it is widely used as a screen display element of a portable information device such as a mobile phone or a notebook computer. In addition, the recent increase in the size of the screen has attracted attention as a home appliances such as TV.

Such a liquid crystal display device has a large disadvantage in view angle characteristics and response speeds in which contrast and color are changed according to the viewing direction of the screen. Various methods have been proposed to overcome these disadvantages.

For example, in order to improve the viewing angle of an LCD (Liquid Crystal Display), a method of attaching a prism plate to the surface of the light guide plate to improve the linearity of incident light from the backlight and improving the luminance in the vertical direction by 30% or more has been put into practical use. A method of increasing the viewing angle by attaching a plate is being applied.

In addition, many attempts have been made to improve the viewing angle and response speed by driving liquid crystals such as OCB, Polymer Dispersed Liquid Crystal (PDLC), and Deformed Helix Ferroelectric (DHF) using TFT (Thin Film Transistor). In particular, in the case of the OCB mode, the response speed of the liquid crystal is fast, and because of the advantages of having a wide viewing angle characteristics, research and development is actively underway.

Next, the operation of the OCB mode described above will be briefly described with reference to FIG. 1.

1 is a view for explaining the operation of the general OCB mode.

Referring to the drawings, the initial alignment state of the liquid crystal positioned between the upper electrode and the lower electrode is a homogenous state (H), and when a predetermined voltage is applied to the upper and lower electrodes, a transient splay; It is converted into a bend state (hereinafter referred to as B) through T) and Asymmetric splay (A), and then operates in OCB mode.

In general, the OCB liquid crystal cell has a pretilt angle of about 10 to 20 °, a thickness of the liquid crystal cell of 1.5 to 2.5 μm, and a rubbing of the alignment layer in the same direction. Since the arrangement of the liquid crystal molecules in the center of the liquid crystal layer is symmetrical, the inclination angle is 0 ° below a certain voltage, and the inclination angle is 90 ° above a specific voltage, so that a large voltage is initially applied to the liquid crystal layer. The inclination angle of the liquid crystal molecules is set to 90 °, and the applied voltage is changed to modulate the polarization of light passing through the liquid crystal layer by changing the tilt of the remaining liquid crystal molecules except for the liquid crystal molecules in the middle of the alignment layer and the liquid crystal layer.

The inclination angle of the liquid crystal molecules in the center is usually several seconds to arrange from 0 ° to 90 °, the cell thickness is thin, the elastic modulus of the bending deformation is large, the reaction time is characterized by very fast as about 10㎳.

However, there occurs a problem that it takes a certain time before the liquid crystal is obtained bend alignment to be driven in the OCB mode. In particular, a high voltage is applied for a short time after the PC monitor or the TV switch is turned on, so that it is possible to use it only when a bend alignment transition is induced in the entire LCD panel.

The present invention is to solve the above problems, so that the transition driving voltage applied to the liquid crystal molecules to the initial bend orientation transition of the liquid crystal molecules so that the phase inversion while discontinuously rising or falling through intermediate levels, An object of the present invention is to provide a method and a device for driving a transition of an OCB liquid crystal display panel which can reduce stress of circuit elements due to a sudden voltage change.

In the transition driving method of the OCB liquid crystal display panel according to the present invention for achieving the above object, the pixel is formed in the region where the scan line for supplying the scan signal and the data line for supplying the data signal intersect and are common to the pixel. In an initial starting condition of an OCB liquid crystal display panel formed so that a line passes, a transition voltage of a pulse waveform in which polarity is inverted with time changes is applied to at least one of the scan line, the data line, and the common line. And the transition voltage rises or falls discontinuously.

The transition voltage applied to the scan lines is maintained at a potential of a first level, the transition voltage applied to the data lines is maintained at a potential of a second level, and a transition voltage whose polarity is inverted with respect to the common lines with time changes. It is preferred to be applied.

The transition period for bend orientation transition of the liquid crystal molecules is a second period in which a negative pulse voltage having a third level is applied to the common lines and a time period that is contiguous in time to the second period. It is preferable to have a third period in which the pulse voltage of is applied to the common lines, and a fourth period in which a negative pulse voltage having a fifth level is applied to the common lines in time. Do.

Wherein the transition period is preceded in time prior to the second period, the first period in which the transition voltage applied to the common lines maintains the ground level, and the subsequent period in time in the fourth period. It is further desirable to have a fifth period during which the transition voltage applied to the lines maintains the ground level.

Preferably, the first level is positive polarity and the second level is ground level.

Preferably, the third level and the fifth level are the same level.

It is preferable that the polarity of the transition voltage applied to the common lines be reversed twice with time.

Each pixel of the OCB liquid crystal display panel includes an OCB type liquid crystal, a pixel electrode connected to the liquid crystal, a gate connected to the scan line and a source connected to the data line, and a drain connected to the pixel electrode. A transistor and a common electrode connected to the common line are provided, and the gate electrode is preferably located above the source electrode and the drain electrode.

A positive pulse voltage having a thirteenth level, wherein the transition period for bend-orienting the liquid crystal molecules is continuous in time in the eleventh period and the eleventh period during which the transition voltage applied to the common lines maintains the ground level. A twelfth period applied to the common lines, a continuation in time in the twelfth period, a thirteenth period in which a negative pulse voltage having a fourteenth level is applied to the common lines, and continually in the thirteenth period 14th period in which a positive pulse voltage having a fifteenth level is applied to the common lines and in time in the fourteenth period, wherein the transition voltage applied to the common lines maintains a ground level. It is desirable to have 15 periods.

Preferably, the transition voltages applied to the scan lines are maintained at the potential of the eleventh level, and the transition voltages applied to the data lines are maintained at the potential of the twelfth level.

Preferably, the eleventh level is negative polarity and the twelfth level is ground level.

It is preferable that the transition voltage of the pulse waveform applied to the common lines rise or fall discontinuously with a time interval, increasing or decreasing exponentially, linearly, or quadraticly.

According to another aspect of the present invention, a transition driving apparatus of an OCB liquid crystal display panel is formed such that a pixel is formed in an area where a scan line for supplying a scan signal and a data line for supplying a data signal intersect, and a common line passes through the pixel. In the initial starting condition of the OCB liquid crystal display panel, a transition voltage of a pulse waveform whose polarity is inverted with time changes is applied to at least one of the scan line, the data line, and the common line, and the transition voltage This discontinuity rises or falls.

A timing controller for generating a data driving signal, a scan driving signal, and a common driving signal corresponding to an image signal to be displayed on the OCB liquid crystal display panel; and a data driving unit for applying a data driving voltage according to the data driving signal to the data lines. Preferably, a scan driver for applying a scan driving voltage according to the scan driving signal to the scan lines and a common driver for applying a common driving voltage according to the common driving signal to the common lines.

According to the present invention, since the transition driving voltage is phase inverted while rising or falling through discontinuous intermediate levels with time intervals, it is possible to reduce stress of circuit elements due to a sudden voltage change.

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

2 to 4 illustrate an embodiment in which a transition driving method of an OCB liquid crystal display panel according to the present invention is applied, and a structure of a thin film transistor (TFT) liquid crystal display (LCD) panel having a top gate structure will be described. As follows.

Referring to the drawings, the thin film transistor (TFT) liquid crystal display (LCD) panel 10 is active by a thin film transistor, which includes a thin film transistor substrate 100, a common electrode substrate 200, and two substrates 100. And the liquid crystal layer 300 injected between the two substrates 200 and the polarizing films 160 and 260 attached to the outer sides of the two substrates 100 and 200, respectively. The liquid crystal display device including the liquid crystal display panel 10 may further include a back light unit (not shown). The present invention can be applied not only to the case where the liquid crystal display panel is active but also to the case of the passive type.

 The thin film transistor substrate 100 illustrated in FIG. 2 includes a thin film transistor having a top gate structure. The thin film transistor substrate 100 includes a first gate 110, an insulating layer 120, pixel electrodes 121 and E, and a source electrode. 122, S, drain electrodes 123 and D, ohmic contact layer 124, semiconductor pattern 125, gate insulating film 126, gate electrodes 127 and G, passivation film 128, first alignment film 130 ), A light shielding film 140, a storage capacitor 150, and a polarizing film 160.

In the thin film transistor substrate 100 having the top gate structure, the light blocking film 140 is formed in a channel region on the insulating first substrate 120, and the insulating film 120 is formed thereon. The data line LD extends in the vertical direction on the insulating layer 120, and a pixel region is formed in an area where the scan line LS intersects the data line LD.

The source electrode 122 protrudes from the data line LD in the scan line LS direction. The drain electrode 123 protrudes from the source electrode 122 in the direction of the scan line LS. The drain electrodes 123 and D are opposite electrodes of the source electrodes 122 and S and extend to the pixel electrodes 121 and E inside the pixel region. In this case, the data line LD may be formed in a double layer or more structure. In this case, at least one layer may be formed of a metal material having low resistance.

In addition, the scan line LS extends to intersect the data line LD, and the gate electrodes 127 and G protrude from the scan line LS in the direction of the data line LD. In the thin film transistor substrate 100 having the top gate structure, the gate electrodes 127 and G are formed on the source electrode 122 and the drain electrode 123. In this case, the scan line LS includes a gate line extending in the horizontal direction and gate electrodes 127 and G protruding from the gate line.

An ohmic contact layer 124, a semiconductor pattern 125, and a gate insulating layer 126 are formed between the gate electrodes 127 and G, the source electrodes 122 and S, and the drain electrodes 123 and D, respectively. In addition, a protective film 180 having a thickness of 1,500 to 2,500 Å made of an insulating material such as silicon nitride or silicon oxide is covered thereon.

The gate insulating layer 126 is formed under the scan line LS including the gate electrodes 127 and G. The gate insulating layer 126 may be formed to have a thickness of 3,500 to 4,500 GPa of an insulating material such as silicon nitride or silicon oxide.

Below the gate insulating layer 126, a semiconductor pattern 125 having a thickness of 800 to 1,500 Å overlapping with the gate electrodes 127 and G and made of amorphous silicon or the like is formed. Under the semiconductor pattern 125, an ohmic contact layer 124 having a thickness of 500 to 800 μm made of amorphous silicon doped with a conductive impurity is formed.

The pixel electrodes 121 and E are connected to the drain electrodes 123 and D, and are formed of a transparent conductive material such as ITO or IZO. On the pixel electrodes 121 and E, the first alignment layer 130 is formed on the entire display area.

The common electrode substrate 200 includes a second substrate 210, a common electrode 221 and a COM, a second alignment layer 230, a polarizing film 260, a color filter 270, and a black matrix 280. .

The black matrix 280 is formed on the insulating second substrate 210 to cover the scan line LS, the data line LD, and a portion of the thin film transistor TFT of the thin film transistor substrate. A color filter 270 may be formed on the second substrate 210 and the black matrix 280 to cover the entire display area of the second substrate 210, and the ITO or IZO may be formed on the bottom surface of the color filter 270. The common electrode 221 made up of COM is covered. The second alignment layer 230 is covered on the lower surface of the common electrode 221.

Meanwhile, the black matrix 280 is disposed to overlap the vertical alignment layer exposed between the horizontal alignment layers when the common electrode substrate 200 is combined with the thin film transistor substrate 100. However, in another embodiment, the horizontal alignment layer may be formed directly below the common electrode 221 and COM, and the vertical alignment layer may be formed in a band shape on the bottom surface of the horizontal alignment layer.

The common electrode substrate 200 and the thin film transistor substrate 100 described above are coupled with a predetermined substrate spacing, and the liquid crystal layer 300 is filled between the two substrates. In addition, due to the vertical alignment layer and the horizontal alignment layer formed on the two substrates 100 and 200, the alignment state of the liquid crystal may vary depending on the position.

It is preferable that the liquid crystal layer 300 filled between the first alignment layer 130 and the second alignment layer 230 be an OCB liquid crystal cell driven in the OCB mode. The OCB liquid crystal cell has a pretilt angle of about 10 to 20 °, a thickness of the liquid crystal cell of 1.5 to 2.5 μm, and a rubbing of the alignment film in the same direction. Since the arrangement of the liquid crystal molecules in the center of the liquid crystal layer is symmetrical, the inclination angle is 0 ° below the specific voltage, and the inclination angle is 90 ° above the specific voltage. Therefore, the inclination angle of the liquid crystal molecules in the center of the liquid crystal layer is initially set at 90 ° by applying a large voltage at an initial stage, and the change in the tilt of the remaining liquid crystal molecules except for the liquid crystal molecules in the center of the alignment layer and the liquid crystal layer by changing the applied voltage. This modulates the polarization of light passing through the liquid crystal layer.

The inclination angle of the liquid crystal molecules in the center is usually several seconds to arrange from 0 ° to 90 °, the cell thickness is thin, the elastic modulus of the bending deformation is large, the reaction time is characterized by very fast as about 10㎳. However, after the switch of the display device is turned on, that is, before driving the liquid crystal display of the liquid crystal display panel, the bend alignment transition is applied to the entire panel through the respective electrode lines LS, LD, and COM according to the present invention. It is necessary to induce.

The polarization axes of the two polarizing films 160 and 260 are arranged to be orthogonal to each other, and preferably arranged to form 45 degrees or 135 degrees with the rubbing direction of the alignment film.

In the liquid crystal display device including the liquid crystal display panel 10, color filters of red, green, and blue colors are applied to the thin film transistor substrate 100 or the common electrode substrate 200 configured by a color filter method of dividing a space. And the backlight emits white light. However, as another embodiment, the liquid crystal display may be implemented by a field sequential (FS) displaying colors by time division. In this case, three-color light sources such as LEDs (light emitting diodes) capable of generating red, green, and blue lights are disposed in the backlight unit.

5 is a waveform diagram schematically showing a transition driving method of an OCB liquid crystal display panel according to another preferred embodiment of the present invention.

Referring to the drawings, according to the transition driving method of the OCB liquid crystal display panel according to the present invention, the scan lines (LS in Fig. 3), data lines (LD in Fig. 3), and common lines at the initial startup of the OCB liquid crystal display panel A transition voltage is applied to each of (COM in FIG. 3) to bend orientation transition the liquid crystal molecules. At least one of the scan lines (LS in FIG. 3), the data lines (LD in FIG. 3), and the common lines (COM in FIG. 3) are inverted in polarity according to a time change, have a time interval, and rise or fall discontinuously. The transition voltage of the pulse waveform is applied.

In the present exemplary embodiment, a first level at which the transition voltage V _gate applied to the gate electrode G of FIG. 3 through the scan line LS in the transition period T _t to which the transition voltage is applied is a positive level. It is maintained at the potential of (V ₁ ). During the transition period T _t to which the transition voltage is applied, the transition voltage V _source applied to the source electrode S of FIG. 3 through the data line LD of FIG. 3 becomes a potential of the second level V _G. maintain. During the transition period T _t to which the transition voltage is applied, the transition voltage V _com applied to the common electrode 221 of FIG. 2 through the common line COM of FIG. 3 has a voltage whose polarity is reversed with time. Is approved.

At this time, the transition period T _t to which the transition voltage is applied is continuous in time according to the change of the transition voltage V _com applied to the common electrode 221 of FIG. 2 through the common line COM of FIG. 3. It is preferable that the first period Ta, the second period Tb, the third period Tc, the fourth period Td, and the fifth period Te are included. In the first period Ta, the transition voltage V _com applied to the common lines maintains the ground level V _G.

In the second period Tb, the transition voltage V _com applied to the common lines maintains the third level V ₃ of negative polarity. That is, the transition voltage V _com applied to the common lines is changed from the ground level V _G of the first period Ta to the voltage V ₃ of the negative level. In the third period Tc, the transition voltage V _com applied to the common lines maintains the fourth level V ₄ of positive polarity. That is, the polarity of the transition voltage V _com applied to the common lines is changed once from the voltage V ₃ of the negative level in the second period Tb to the voltage V ₄ of the positive level.

In the fourth period Td, the transition voltage V _com applied to the common lines maintains the fifth level V ₅ of negative polarity. That is, the polarity of the transition voltage V _com applied to the common lines is changed twice from the positive voltage V ₄ of the third period Tc to the negative voltage V ₅ . In the fifth period Te, the transition voltage V _com applied to the common lines maintains the ground level V _G. That is, the transition voltage V _com applied to the common lines is changed from the voltage V ₅ of the negative level in the fourth period Td to the ground level V _G.

In this case, the third level V ₃ of the second period Tb and the fifth level V ₅ of the fourth period Td are preferably at the same level so that a common voltage source can be used.

In the first period Ta, the common lines COM of FIG. 3 maintain the ground level V _G , and the scan lines LS of FIG. 3 maintain the first level V ₁ , for example, a voltage of + 12V. The data line LD of FIG. 3 maintains the ground level V _G. Accordingly, a relatively weak potential difference (V _gate −V _com ), for example, +12 V is formed between the gate electrode G and the common electrode COM, thereby removing residual charge remaining in the liquid crystal so as to be in a stable state. The liquid crystal is prepared to be effectively transitioned to the bend alignment state by the transition voltage applied in the second period Tb to the fourth period Td.

In the second period Tb, the scan line (LS in FIG. 3) maintains the first level V ₁ , for example, a voltage of +12 V, and the ground line V _{G in the} data line (LD in FIG. 3). In this state, the transition voltage V _com applied to the common lines COM is changed from the ground level V _G of the first period Ta to a negative level voltage V ₃ , for example, -18 V. . Thus, a relatively strong potential difference (V _gate −V _com ), for example, +30 V is formed between the gate electrode G and the common electrode COM, so that the liquid crystal starts to transition to the bend alignment state.

In this case, as shown in FIG. 4, a high voltage is first applied to a portion where a thin film transistor is formed first to form a transition nucleus, and then transition nuclei are grown to other portions of the liquid crystal so that the entire region of the liquid crystal may bend-aligned. Be prepared to be. Therefore, the liquid crystal can be in a bend alignment transition state in a short time at low voltage.

In particular, when applied to a thin film transistor liquid crystal display panel having a top gate structure as in the present embodiment, the potential difference between the gate electrode 127 of FIG. 2 and the common electrode 221 of FIG. 2 V _gate -V _com . Becomes + 30V, and the potential difference (V _source -V _com ) between the source electrode (122 in FIG. 2) and the common electrode (221 in FIG. 2) becomes 0V. Thus, the lateral electric field between the liquid crystal portion between the gate electrode (127 in FIG. 2) and the common electrode (221 in FIG. 2) and the liquid crystal portion between the source electrode (122 in FIG. 2) and the common electrode (221 in FIG. 2). a lateral field is formed.

Accordingly, the transition nucleus formed in the liquid crystal portion between the gate electrode (127 in FIG. 2) and the common electrode (221 in FIG. 2) is the liquid crystal portion between the source electrode (122 in FIG. 2) and the common electrode (221 in FIG. 2). It can be easily transitioned in the direction of. Therefore, as the transition nucleus formed in some regions of the liquid crystal first grows to other portions of the liquid crystal, the entire liquid crystal region may be transferred to the bend state at a high speed even at a low voltage.

In the third period Tc, the scan line (LS in FIG. 3) maintains the first level V ₁ , for example, a voltage of +12 V, and the ground level V _{G in the} data line (LD in FIG. 3). In this state, the transition voltage V _com applied to the common lines COM is the voltage V ₃ of the negative level of the second period Tb, for example, from -18V to the voltage V ₄ of the positive level. For example, its polarity is changed first to + 18V. Accordingly, a potential difference V _gate -V _com , for example, -6 V, having an inverted phase is formed between the gate electrode G and the common electrode COM.

As the polarity of the transition voltage V _com applied to the common lines COM is changed, the polarity of the potential difference V _gate -V _com between the gate electrode G and the common electrode COM is also inverted. That is, the electric field between the liquid crystal molecules is reversed to shake the liquid crystal molecules, thereby inducing dynamic characteristics of the liquid crystal molecules. Therefore, the transition of the liquid crystal to the bend state can be made within a short time even at a low voltage.

In the fourth period Td, the scan line (LS in FIG. 3) maintains a first level (V ₁ ), for example, a voltage of +12 V, and the ground level (V _G ) in the data line (LD in FIG. 3). In this state, the transition voltage V _com applied to the common lines COM is the voltage V ₄ of the positive level of the third period Tc, for example, from + 18V to the voltage V ₅ of the negative level. For example, its polarity is changed to -18V for the second time. Accordingly, a potential difference V _gate −V _com , for example, +30 V, having an inverted phase is formed between the gate electrode G and the common electrode COM.

As the polarities of the transition voltages V _com applied to the common lines COM are changed, the potential difference V _gate −V _com between the gate electrode G and the common electrode COM is inverted again. do. That is, the electric field between the liquid crystal molecules is inverted again to shake the liquid crystal molecules, thereby inducing dynamic characteristics of the liquid crystal molecules. Therefore, the transition of the liquid crystal to the bend state can be made within a short time even at a low voltage.

Further, residual liquid crystal molecules remaining without transitioning to the bend state until the third period Tc by the potential difference V _gate −V _com , for example, +30 V between the gate electrode G and the common electrode COM are stored. Transition to the bend state to complete the bend state transition of the liquid crystal.

In the fifth period Te, the scan line (LS in FIG. 3) maintains the first level V ₁ , for example, a voltage of +12 V, and the ground level V _{G in the} data line (LD in FIG. 3). In this state, the transition voltage V _com applied to the common lines COM is changed from the negative voltage V ₅ of the fourth period Td, for example, from -18 V to the ground level V _G. .

Accordingly, a relatively weak potential difference (V _gate −V _com ), for example, +12 V is formed between the gate electrode G and the common electrode COM, thereby removing residual charge remaining in the liquid crystal so as to be in a stable state. The state of the liquid crystal may be prepared so that the display driving of the normal liquid crystal subsequent to the fifth period Te may be stably performed.

In the second period Tb, the third period Tc, and the fourth period Td, a transition voltage of a pulse waveform in which a phase is inverted with the progress of each period is applied to the common lines COM. . As shown, as each period progresses, the transition voltage V _com rises or decreases discontinuously with discontinuous increase with time, and its phase is reversed.
At this time, as shown in the figure, the transition voltage rises or falls, including a plurality of rising steps, and each rising step includes a rising period in which the voltage is raised and a sustaining period in which the voltage is maintained. Each of the falling steps includes a falling period in which the voltage falls and a sustaining period in which the voltage is maintained.
At this time, the rising and falling times t _r and t _f may be increased exponentially or linearly or quadraticly, while increasing or discontinuously increasing while falling discontinuously.
In other words, it is preferable that the transition voltage of the pulse waveform applied to the common lines increases exponentially, linearly, or quadraticly with time change in each rising period. In addition, it is preferable to decrease exponentially, linearly, or quadraticly with each change in the period of descent.

Therefore, since the transition driving voltage rises or falls while increasing or decreasing little by little at a time interval to reach the voltage value of the applied pulse, it is possible to reduce the stress of the circuit elements due to the sudden voltage change. In addition, since the transition voltage rises or falls with sufficient time, the liquid crystal molecules receive the continuous energy of the applied voltage, and exhibit excellent and dynamic characteristics, so that the transition of the liquid crystal to the bend state can be made more smoothly.

6 is a waveform diagram schematically illustrating a transition driving method of an OCB liquid crystal display panel according to another exemplary embodiment of the present invention.

Referring to the drawings, according to the transition driving method of the OCB liquid crystal display panel according to the present invention, the scan lines (LS in Fig. 3), data lines (LD in Fig. 3), and common lines at the initial startup of the OCB liquid crystal display panel A transition voltage is applied to each of (COM in FIG. 3) to bend orientation transition the liquid crystal molecules. At least one of the scan lines (LS in FIG. 3), the data lines (LD in FIG. 3), and the common lines (COM in FIG. 3) are inverted in polarity according to a time change, have a time interval, and rise or fall discontinuously. The transition voltage of the pulse waveform is applied.

This embodiment is intended to achieve the same purpose as the embodiment shown in FIG. 5, and for the embodiment shown in FIG. 5, through the scan line (LS in FIG. 3) during the transition period T _{t1 to} which the transition voltage is applied. The phase of the transition voltage V _com applied to the common electrode 221 of FIG. 2 is changed through the transition voltage V _gate applied to the gate electrode G of FIG. 3 and the common line COM of FIG. 3. Yes. Except the matters described below, the parts are the same as those in the embodiment shown in FIG. 5 and the description thereof is omitted.

In the present embodiment, the eleventh level at which the transition voltage V _gate applied to the gate electrode G of FIG. 3 through the scan line LS in the transition period T _t1 to which the transition voltage is applied is a negative level. It is held at the potential of (V ₁₁ ). During the transition period T _t1 to which the transition voltage is applied, the transition voltage V _source applied to the source electrode S of FIG. 3 through the data line LD of FIG. 3 is brought to the potential of the twelfth level V _G. maintain. During the transition period T _t1 to which the transition voltage is applied, the transition voltage V _com applied to the common electrode 221 of FIG. 2 through the common line COM of FIG. 3 has a voltage whose polarity is reversed with time. Is approved.

At this time, the transition period T _t1 to which the transition voltage is applied is continuous in time according to the change of the transition voltage V _com applied to the common electrode 221 of FIG. 2 through the common line COM of FIG. 3. The first period T1, the second period T2, the third period T3, the fourth period T4, and the fifth period T5 are preferably provided.

In the first period T1, the transition voltage V _com applied to the common lines maintains the ground level V _G. In the second period T2, the transition voltage V _com applied to the common lines maintains the thirteenth level V ₁₃ of positive polarity. That is, the transition voltage V _com applied to the common lines is changed from the ground level V _G of the first period T1 to the positive voltage V ₁₃ . In the third period T3, the transition voltage V _com applied to the common lines maintains the fourteenth level V ₁₄ of negative polarity. That is, the polarity of the transition voltage V _com applied to the common lines is changed from the positive voltage V ₁₃ of the second period T2 to the negative voltage V ₁₄ .

In the fourth period T4, the transition voltage V _com applied to the common lines maintains the fifteenth level V ₁₅ of positive polarity. That is, the polarity of the transition voltage V _com applied to the common lines is changed from the negative level voltage V ₁₄ of the third period T3 to the positive level voltage V ₁₅ . In the fifth period T5, the transition voltage V _com applied to the common lines maintains the ground level V _G. That is, the transition voltage V _com applied to the common lines is changed from the voltage V ₁₅ of the positive level in the fourth period T4 to the ground level V _G.

In this case, the thirteenth level V ₁₃ of the second period T2 and the fifteenth level V ₁₅ of the fourth period T4 are preferably the same level so that a common voltage source can be used.

In the second period T2, the third period T3, and the fourth period T4, transition voltages of a pulse waveform in which phases are reversed as the respective periods progress are applied to the common lines COM. . As shown, as each period progresses, the transition voltage V _com rises or decreases discontinuously with discontinuous increase with time, and its phase is reversed.
At this time, as shown in the figure, the transition voltage rises or falls, including a plurality of rising steps, and each rising step includes a rising period in which the voltage is raised and a sustaining period in which the voltage is maintained. Each of the falling steps includes a falling period in which the voltage falls and a sustaining period in which the voltage is maintained.
At this time, the rising and falling times t _r and t _f may be increased exponentially or linearly or quadraticly, while increasing or discontinuously increasing while falling discontinuously.
In other words, it is preferable that the transition voltage of the pulse waveform applied to the common lines increases exponentially, linearly, or quadraticly with time change in each rising period. In addition, it is preferable to decrease exponentially, linearly, or quadraticly with each change in the period of descent.

Therefore, since the transition driving voltage rises or falls while increasing or decreasing little by little at a time interval to reach the voltage value of the applied pulse, it is possible to reduce the stress of the circuit elements due to the sudden voltage change. In addition, since the transition voltage rises or falls with sufficient time, the liquid crystal molecules receive the continuous energy of the applied voltage, and exhibit excellent and dynamic characteristics, so that the transition of the liquid crystal to the bend state can be made more smoothly.

7 is a block diagram schematically showing a transition driving apparatus of an OCB liquid crystal display panel as a preferred embodiment according to the present invention.

Referring to the drawings, the transition driving apparatus 700 of the OCB LCD panel includes a timing controller 710, a data driver 720, a scan driver 730, a common driver 740, a gray voltage generator 750, And a light source controller 760. The transition driving apparatus 700 of the OCB liquid crystal display panel according to the present embodiment is a driving device to which the transition driving method of the OCB liquid crystal display panel of FIGS. 5 and 6 is applied. Therefore, the descriptions of FIGS. 5 and 6 also apply to the transition driving apparatus 700 of the OCB liquid crystal display panel according to the present embodiment.

The timing controller 710 receives a gray scale data signal (R, G, B DATA), a horizontal sync signal (Hsync), a vertical sync signal (Vsync) from an external or graphic controller (not shown), OCB liquid crystal display panel Gray level data (R, G, B DATA), data driving signal (Sd), scan driving signal (Sg), common driving signal (Sc), and light source control signal (Sb) corresponding to the video signal to be displayed are generated. .

The data driver 720 applies a data transition voltage V _source corresponding to the data driving signal Sd to the data lines LD. The scan driver 730 applies a scan transition voltage V _gate corresponding to the scan driving signal Sg to the scan lines LS. The common driver 740 applies the common transition voltage V _com according to the common driving signal Sc to the common lines COM.

The manufacturing voltage generator 750 outputs a gray level signal corresponding to the gray level data R, G, and B data to the data driver 720. The light source controller 760 controls the backlight 400 according to the light source control signal Sb.

In particular, in the second period, the third period, and the fourth period, the transition voltage of the pulse waveform in which the phase is reversed with the progress of each period is applied to the common lines COM. As shown, as each period progresses, the transition voltage V _com rises discontinuously with time intervals and decreases or decreases discontinuously, so that its phase is reversed.
At this time, as shown in the figure, the transition voltage rises or falls, including a plurality of rising steps, and each rising step includes a rising period in which the voltage is raised and a sustaining period in which the voltage is maintained. Each of the falling steps includes a falling period in which the voltage falls and a sustaining period in which the voltage is maintained.
At this time, the rise and fall times (t _r , t _f ) is preferably exponentially, linearly or quadratic, while increasing discontinuously or falling discontinuously.
In other words, it is preferable that the transition voltage of the pulse waveform applied to the common lines increases exponentially, linearly, or quadraticly with time change in each rising period. In addition, it is preferable to decrease exponentially, linearly, or quadraticly with each change in the period of descent.

According to the transition driving method and apparatus of the OCB liquid crystal display panel according to the present invention, since the driving voltage is phase inverted while rising or falling through discontinuous intermediate levels with time intervals, the stress of the circuit elements due to a sudden voltage change Can be reduced.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, it is merely an example, and those skilled in the art may realize various modifications and equivalent other embodiments therefrom. I can understand. Accordingly, the true scope of protection of the invention should be defined only by the appended claims.

Claims (19)

In an initial starting condition of an OCB liquid crystal display panel in which a pixel is formed in an area where a scan line for supplying a scan signal and a data line for supplying a data signal cross, and a common line passes through the pixel, A transition voltage of a pulse waveform whose polarity is inverted with time changes is applied to at least one of the scan line, the data line, and the common line, The transition voltage rises including a plurality of rising steps or falls including a plurality of falling steps, Wherein each rising step includes a rising period during which the voltage rises and a sustain period during which the voltage is maintained, and wherein each falling step includes a falling period during which the voltage falls and a holding period during which the voltage is maintained. Transition drive method. The method of claim 1, A transition voltage applied to the scan lines is maintained at a potential of a first level, A transition voltage applied to the data lines is maintained at a potential of a second level, A transition driving method of an OCB liquid crystal display panel in which a transition voltage whose polarity is inverted with time changes is applied to the common lines. The method of claim 2, Liquid crystal molecules are located in the pixel, A transition period in which the liquid crystal molecules bend-orientate transition is a second period in which a negative pulse voltage having a third level is applied to the common lines and in time in the second period. An OCB liquid crystal having a third period in which a pulse voltage of is applied to the common lines, and a fourth period in which a negative pulse voltage having a fifth level is applied to the common lines in time, and continuously in the third period. Transition driving method of display panel. The method of claim 3, Wherein the transition period is preceded in time prior to the second period, the first period in which the transition voltage applied to the common lines maintains the ground level, and the subsequent period in time in the fourth period. A transition driving method of an OCB liquid crystal display panel further comprising a fifth period in which the transition voltage applied to the lines maintains the ground level. The method of claim 2, And the first level has a positive polarity and the second level has a ground level. The method of claim 3, And the third level and the fifth level are the same level. The method of claim 2, A transition driving method of an OCB liquid crystal display panel in which the polarity of the transition voltage applied to the common lines is inverted twice with time. The method of claim 1, Each pixel of the OCB liquid crystal display panel includes an OCB type liquid crystal, a pixel electrode connected to the liquid crystal, a gate connected to the scan line and a source connected to the data line, and a drain connected to the pixel electrode. A transistor and a common electrode connected to the common line; The gate driving method of the OCB liquid crystal display panel is positioned above the source electrode and the drain electrode. The method of claim 1, Liquid crystal molecules are located in the pixel, A positive pulse voltage having a thirteenth level, wherein the transition period for bending the liquid crystal molecules to bend-oriented transitions is continuous in time in the eleventh period and the eleventh period during which the transition voltage applied to the common lines maintains a ground level. A twelfth period applied to the common lines, a continuation in time in the twelfth period, a thirteenth period in which a negative pulse voltage having a fourteenth level is applied to the common lines, and continually in the thirteenth period 14th period in which a positive pulse voltage having a fifteenth level is applied to the common lines and in time in the fourteenth period, wherein the transition voltage applied to the common lines maintains a ground level. A transition driving method of an OCB liquid crystal display panel having 15 periods. The method of claim 9, The transition voltages applied to the scan lines are maintained at the potential of the eleventh level, A transition driving method of an OCB liquid crystal display panel in which a transition voltage applied to the data lines is maintained at a potential of a twelfth level. The method of claim 10, And a twelfth level is a negative polarity and the twelfth level is a ground level. The method of claim 9, Each pixel of the OCB liquid crystal display panel includes an OCB type liquid crystal, a pixel electrode connected to the liquid crystal, a gate connected to the scan line and a source connected to the data line, and a drain connected to the pixel electrode. A transistor and a common electrode connected to the common line; The gate driving method of the OCB liquid crystal display panel is positioned above the source electrode and the drain electrode. The method according to any one of claims 2 to 12, Transition voltage of the pulse waveform applied to the common lines, In each of the rising periods exponentially, or linearly, or quadraticly with time change, and in each of the falling periods exponentially, or linearly, or 2 A transition driving method of an OCB liquid crystal display panel which decreases functionally. In an initial starting condition of an OCB liquid crystal display panel in which a pixel is formed in an area where a scan line for supplying a scan signal and a data line for supplying a data signal cross, and a common line passes through the pixel, A transition voltage of a pulse waveform whose polarity is inverted with time changes is applied to at least one of the scan line, the data line, and the common line, The transition voltage rises including a plurality of rising steps or falls including a plurality of falling steps, Wherein each rising step includes a rising period during which the voltage rises and a sustain period during which the voltage is maintained, and wherein each falling step includes a falling period during which the voltage falls and a holding period during which the voltage is maintained. Transition drive. The method of claim 14, A timing controller for generating a data driving signal, a scan driving signal, and a common driving signal corresponding to an image signal to be displayed on the OCB liquid crystal display panel; and a data driving unit for applying a data driving voltage according to the data driving signal to the data lines. And a scan driver for applying a scan driving voltage according to the scan driving signal to the scan lines, and a common driver for applying a common driving voltage according to the common driving signal to the common lines. . The method of claim 15, The transition voltage applied to the scan lines is maintained at a potential of a first level of positive polarity, the transition voltage applied to the data lines is maintained at a potential of a second level of a ground level, and the time line changes to the common lines. The OCB liquid crystal display panel transition driving device is applied a transition voltage of which polarity is inverted accordingly. The method of claim 16, Liquid crystal molecules are located in the pixel, The transition period for bend orientation transition of the liquid crystal molecules is a first period in which the transition voltage applied to the common lines maintains a ground level, and is temporally continuous in the first period, and has a negative pulse voltage having a third level. A second period applied to the common lines, a time continuous in the second period, a third period in which a positive pulse voltage having a fourth level is applied to the common lines, and temporally continuous in the third period And a fourth period in which a negative pulse voltage having a fifth level is applied to the common lines, and a time period that is continuous in the fourth period, and has a fifth period of maintaining a ground level. Transition drive system. The method of claim 15, Liquid crystal molecules are located in the pixel, The transition voltage applied to the scan lines is maintained at the potential of the eleventh level of negative polarity, the transition voltage applied to the data lines is maintained at the potential of the twelfth level of the ground level, A positive pulse voltage having a thirteenth level, wherein the transition period for bending the liquid crystal molecules to bend-oriented transitions is continuous in time in the eleventh period and the eleventh period during which the transition voltage applied to the common lines maintains a ground level. A twelfth period applied to the common lines, a continuation in time in the twelfth period, a thirteenth period in which a negative pulse voltage having a fourteenth level is applied to the common lines, and continually in the thirteenth period 14th period in which a positive pulse voltage having a fifteenth level is applied to the common lines and in time in the fourteenth period, wherein the transition voltage applied to the common lines maintains a ground level. A transition drive device for an OCB liquid crystal display panel having 15 periods. The method according to any one of claims 16 to 18, Transition voltage of the pulse waveform applied to the common lines, In each of the rising periods exponentially, or linearly, or quadraticly with time change, and in each of the falling periods exponentially, or linearly, or 2 A transition driving device of an OCB liquid crystal display panel which decreases functionally.

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