KR101837143B1 - Liquid crystal display driving device and liquid crystal display using the same - Google Patents

Liquid crystal display driving device and liquid crystal display using the same Download PDF

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KR101837143B1
KR101837143B1 KR1020160027686A KR20160027686A KR101837143B1 KR 101837143 B1 KR101837143 B1 KR 101837143B1 KR 1020160027686 A KR1020160027686 A KR 1020160027686A KR 20160027686 A KR20160027686 A KR 20160027686A KR 101837143 B1 KR101837143 B1 KR 101837143B1
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voltage
vcom2
liquid crystal
vcom1
driver
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KR1020160027686A
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KR20170104810A (en
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조아라
김민석
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주식회사 라온텍
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3648—Control of matrices with row and column drivers using an active matrix
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3696—Generation of voltages supplied to electrode drivers
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2230/00—Details of flat display driving waveforms
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0252—Improving the response speed

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

The LCD driver includes a first driver for controlling a first voltage applied to a first electrode connected to a capacitor provided in a unit pixel located on a driving substrate of a liquid crystal panel, And a second driver for controlling the second voltage Vcom2 applied to the electrodes, wherein the first voltage Vcom1 and the second voltage Vcom2 are individually controlled by the first driver and the second driver. Thus, by increasing the effective response time of the display, it is possible to improve the luminance, improve the response speed of the liquid crystal without adding a lookup table or a memory for the improvement, and in using the field sequential color scheme, Color blending between R, G, and B colors can be prevented within a rate, and a flicker of a screen can be improved by implementing a high frame rate.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LCD driving apparatus and a liquid crystal display apparatus using the same, and more particularly, to an LCD driving apparatus in which a voltage applied to a pixel circuit and a voltage applied to a top plate of a liquid crystal panel are separately driven, And a liquid crystal display device.

2. Description of the Related Art A liquid crystal display (LCD) is composed of two opposing substrates and a liquid crystal filled in a cell gap between the substrates. The liquid crystal controls the transmittance of light supplied from a backlight, Display.

The liquid crystal display device is a portable electronic device such as a smart phone, a smart watch, a tablet PC, a notebook, a personal digital assistants (PDA), an MP3 player, a camera, a camcorder, , Refrigerators, air conditioners, and microwave ovens, as well as products requiring display such as industrial control devices, medical devices, and the like.

Thus broadly liquid crystal display device which is used is, as can be seen in the following formulas 1 and 2, characteristics of the liquid crystal inherent response time is slow because (viscosity, elasticity and the like), wherein the voltage (V a) that the response speed of the liquid crystal is applied Inversely.

Figure 112016022384673-pat00001
(Equation 1)

Figure 112016022384673-pat00002
(Equation 2)

Here, τ r is a rising time when a voltage is applied to the liquid crystal, V a is an applied voltage, V F is a Freederick Transition Voltage at which the liquid crystal molecules start to tilt, Is the cell gap of the cell, γ is the rotational viscosity of the liquid crystal molecule, τ f is the falling time at which the liquid crystal is restored to its original state by the elastic restoring force after the voltage applied to the liquid crystal is turned off, K Denotes the inherent elastic modulus of the liquid crystal, and [Delta] denotes the permittivity.

Conventionally, a cold cathode fluorescent lamp (CCFL) has been mainly used as a backlight unit, but LED (Light Emitting Diode) is widely used according to demands for miniaturization. Particularly, in order to improve the image quality of a liquid crystal display using an LED backlight unit, a field sequential color (FSC) method is widely used.

In a field sequential color liquid crystal display device in which colors are divided into a plurality of fields that sequentially operate R (red), G (green) and B (blue) colors, the lines are sequentially addressed, Addressing a line requires more than a few milliseconds.

In a liquid crystal display device having a conventional pixel circuit, display without mixing of RGB is possible only in a section in which there is no luminance difference between the initial line and the latter line and in a section except for the liquid crystal response time because of the difference between the line addressing time and the on / off time of the backlight did.

In an environment maintaining a frame rate of 80 Hz in which no color separation or screen flicker occurs, the interval without mixing of RGB colors is less than 20% of the interval of each color representation, so that the screen brightness of the liquid crystal display device is low There is a problem.

In order to solve such a problem, various methods for improving liquid crystal response time have been proposed. As an example, there is a method using a look-up table. This is a method of modulating data according to a change in data using a lookup table, and compensates data modulated with a slower liquid crystal response time by data values. This method improves the liquid crystal response speed by modulating the applied voltage (V a ) of | V a 2 -V f 2 | which is the denominator element of (formula 1) above. However, since additional memory is required for the lookup table, there is a problem that the area is consumed. On the other hand, even when the pixel storage circuit is designed using a low-voltage transistor, a method of periodically switching the voltage on the opposite side of the liquid crystal to be opposite to the applied liquid crystal voltage is applied to make a sufficient voltage difference necessary for driving the liquid crystal, can do. However, in the case of using the field sequential color method, this method causes another problem that acts as a cause of reducing the display valid time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an LCD driving device and a liquid crystal display device capable of improving brightness by increasing the effective response time of a display.

Another object of the present invention is to provide an LCD driving apparatus and a liquid crystal display apparatus which can improve a response speed of a liquid crystal without adding a lookup table or a memory therefor.

It is another object of the present invention to provide an LCD driving device and a liquid crystal display device which can prevent color mixing between R, G and B colors within the same frame rate by using the field sequential color method have.

It is another object of the present invention to provide an LCD driving device and a liquid crystal display device which can realize a high frame rate to improve flicker of a screen.

According to an aspect of the present invention, there is provided an LCD driving apparatus including a first driver for controlling a first voltage (Vcom1) applied to a first electrode connected to a capacitor provided in a unit pixel located on a driving substrate of a liquid crystal panel; And a second driver for controlling a second voltage (Vcom2) applied to a second electrode of the upper panel of the liquid crystal panel, wherein the first voltage (Vcom1) and the second voltage (Vcom2) 1 driver and the second driver.

The second driver applies the second voltage (Vcom2) of a predetermined magnitude to the second electrode, and the first driver supplies the modulated first voltage (Vcom1_m) before the pixel data voltage transfer (global transfer) Is applied to the first electrode and is then returned to the first voltage (Vcom1) before being modulated, so that the voltage applied to the liquid crystal can be instantaneously modulated.

The modulated first voltage Vcom1_m has a lower voltage value Vcom1_mL than the first voltage Vcom1 before modulation in a negative field and a first voltage Vcom1_mL before a modulation in a positive field, (Vcom1_mH) higher than the voltage value Vcom1.

The first driver applies the first voltage (Vcom1) of a predetermined magnitude to the first electrode, and the second driver applies a second voltage (Vcom2_m ) Is applied to the second electrode, and then the voltage is returned to the second voltage (Vcom2) before modulation, whereby the voltage applied to the liquid crystal can be instantaneously modulated.

The modulated second voltage Vcom2_m has a voltage value Vcom2_mH higher than the second voltage Vcom2 before modulation in the negative field and a second voltage Vcom2_mH before the modulation in the positive field. (Vcom2_mL) lower than the voltage value Vcom2 (Vcom2).

The first driver alternately modulates the first voltage (Vcom1) to a high level (VH) and a low level (VL) before every address of a new data, and the second driver It is possible to alternately modulate the second voltage Vcom2 to a high level VH and a low level VL every time a global reset is performed.

The first driver may apply the modulated first voltage (Vcom1_m) to the first electrode before returning to pixel data voltage transfer (Global Transfer), and then return to the first voltage (Vcom1) before modulation .

The modulated first voltage Vcom1_m has a voltage value Vcom1_mL lower than the first voltage Vcom1 before modulation in the negative field and a first voltage Vcom1_mL before the modulation in the positive field. (Vcom1_mH) higher than Vcom1 (Vcom1).

The second driver may apply the modulated second voltage Vcom2_m to the second electrode in the pixel data voltage transfer period (Global Transfer) and then return to the second voltage Vcom2 before modulation have.

The modulated second voltage Vcom2_m has a voltage value Vcom2_mH higher than the unmodulated second voltage Vcom2 in the negative field and a second voltage Vcom2_mH in the positive field, (Vcom2_mL) lower than the voltage value Vcom2 (Vcom2).

According to another aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal panel and a backlight unit, including: a first electrode connected to a capacitor provided in a unit pixel located on a driving substrate of the liquid crystal panel; A second electrode provided on the upper plate of the liquid crystal panel; A first driver for controlling a first voltage (Vcom1) applied to the first electrode; And a second driver for controlling a second voltage (Vcom2) applied to the second electrode, wherein the first voltage (Vcom1) and the second voltage (Vcom2) are applied to the first driver Respectively.

The second driver applies the second voltage (Vcom2) of a predetermined magnitude to the second electrode, and the first driver supplies the modulated first voltage (Vcom1_m) before the pixel data voltage transfer (Global Transfer) Is applied to the first electrode and is then returned to the first voltage (Vcom1) before being modulated, so that the voltage applied to the liquid crystal can be instantaneously modulated.

The modulated first voltage Vcom1_m has a voltage value Vcom1_mL lower than the first voltage Vcom1 before modulation in the negative field and a first voltage Vcom1_mL before the modulation in the positive field. (Vcom_mH) higher than the voltage value (Vcom1).

The first driver applies the first voltage (Vcom1) of a predetermined magnitude to the first electrode, and the second driver applies a second voltage (Vcom2_m ) Is applied to the second electrode, and then the voltage is returned to the second voltage (Vcom2) before modulation, whereby the voltage applied to the liquid crystal can be instantaneously modulated.

The modulated second voltage Vcom2_m has a voltage value Vcom_mH higher than the second voltage Vcom2 before modulation in a negative field and a second voltage Vcom_mH before a modulation in a positive field. (Vcom2_mL) lower than the voltage value Vcom2 (Vcom2).

The first driver alternately modulates the first voltage (Vcom1) to a high level (VH) and a low level (VL) before every address of a new data, and the second driver It is possible to alternately modulate the second voltage Vcom2 to a high level VH and a low level VL every time a global reset is performed.

The first driver may apply the modulated first voltage Vcom1_m to the first electrode before the pixel data transfer (global transfer), and then apply the first voltage (Vcom1) before the modulation to the first electrode .

The modulated first voltage Vcom1_m has a voltage value Vcom1_mL lower than the first voltage Vcom1 before modulation in a negative field and a first voltage Vcom1_mL before a modulation in a positive field. (Vcom1_mH) higher than Vcom1 (Vcom1).

In addition, the second driver may apply the second voltage (Vcom2_m) modulated in the pixel data voltage transfer period (Global transfer) to the second electrode, and then apply the second voltage (Vcom2) have.

The modulated second voltage Vcom2_m has a voltage value Vcom2_mH higher than the second voltage Vcom2 before modulation in the negative field and a second voltage Vcom2_mH before the modulation in the positive field. (Vcom2_mL) lower than the voltage value Vcom2 (Vcom2).

Also, the liquid crystal display device may drive the backlight unit in a field sequential color (FSC) manner.

According to the LCD driving apparatus and the liquid crystal display according to the present invention, it is possible to improve the brightness by improving the effective response time of the display, and to improve the response speed of the liquid crystal without adding a lookup table or a memory therefor , It is possible to prevent color blending between R, G, and B colors within the same frame rate by using the field sequential color system, and to improve the flicker of the screen by implementing a high frame rate.

1 is a schematic view of a liquid crystal display device according to the present invention.
2 is a diagram for explaining the operation of the gate driver and the structure of the pixel array.
3 is a diagram showing a first embodiment of a pixel circuit used in a liquid crystal display device according to the present invention.
4 is a diagram showing a second embodiment of a pixel circuit used in a liquid crystal display device according to the present invention.
5 is a timing chart of Vcom modulation in the pixel circuit of FIG.
Fig. 6 is a diagram for explaining the first driving method of the liquid crystal display device according to the present invention, and shows the response waveform in the case of overdriving using the fixed Vcom method in the pixel circuit of Fig.
Fig. 7 is a diagram for explaining a second driving method of the liquid crystal display device according to the present invention. Fig. 7 shows a response waveform when over driving is performed using the fixed Vcom method in the pixel circuit of Fig.
Fig. 8 is a diagram for explaining a third driving method of the liquid crystal display device according to the present invention. Fig. 8 shows a response waveform in the case of overdriving using the variable Vcom method in the pixel circuit of Fig.
Fig. 9 is a view for explaining a fourth driving method of the liquid crystal display device according to the present invention, and shows the response waveform in the case of overdriving using the variable Vcom method in the pixel circuit of Fig.

Hereinafter, an LCD driving apparatus and a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings. Each embodiment described below is only an example for understanding the present invention and is not intended to limit the structure, use, and application of the present invention. The description of the embodiments of the present invention can be understood in connection with the accompanying drawings, and the attached drawings can be regarded as part of the description of the present invention.

1 is a schematic view of a liquid crystal display device 100 according to the present invention.

A liquid crystal display 100 according to the present invention includes a liquid crystal panel 110, a gate driver 120, a data driver 130, a timing controller 140, a backlight unit 150, and a driver unit 160.

In the liquid crystal panel 110, a plurality of gate lines and data lines intersect to form a pixel region (an enlarged region indicated by a dashed line in Fig. 1). A liquid crystal is filled between the driving substrate 111 and the upper plate 112 of the liquid crystal panel 110 and an electric field corresponding to a difference between a voltage applied to the upper plate 112 and a voltage applied to the pixel electrode And the liquid crystal controls the transmittance of light corresponding to the intensity of the electric field. At this time, the storage capacitor Cst provided in the pixel circuit maintains the pixel voltage supplied to the liquid crystal capacitor Cl and allows the light to transmit for a predetermined time.

As shown in FIG. 2, the gate driver 120 sequentially supplies the first driving signal to the gate line based on the control signal received by the timing controller 140.

The data driver 130 applies an image signal to the data line in synchronization with the first driving signal, based on the control signal and the image signal received from the timing controller 140. At this time, the time to scan the gate line as a whole once is called a frame time, and is shown in FIG.

The timing controller 140 generates and transmits a control signal for driving the gate driver 120 and the data driver 130 based on the control signal received from the system and supplies the image signal received from the system to the data driver 130 ).

The liquid crystal display 100 according to the present invention can use the field sequential color scheme. At this time, the backlight unit 150 includes three light sources of R (red), G (green), and B (blue) colors.

In the field sequential color system, a frame for scanning the gate line as a whole is divided into three fields of an R field, a G field, and a B field, and the R light source, the G light source, and the B light source are sequentially turned on repeatedly. Each field can be divided into an address period (Address), a reset period (Global Reset) for resetting the liquid crystal, and a transfer period (Global Transfer) for transferring the pixel data voltage.

The driver unit 160 included in the liquid crystal display device and the LCD driving apparatus according to the present invention includes a first driver 161 and a second driver 162.

The first driver 161 controls the first voltage Vcom1 applied to the first electrode connected to the capacitor provided in the pixel region of the driving substrate 111 of the liquid crystal panel 110, Controls the second voltage (Vcom2) applied to the second electrode of the upper panel (112) of the liquid crystal panel (110). As described above, the liquid crystal display 100 according to the present invention includes two Vcom voltage sources controlled separately.

The pixel circuit that can be used in the liquid crystal display device and the LCD driving device according to the present invention can be implemented by the circuit according to the embodiment of Figs. 3 and 4, but is not limited thereto.

The pixel circuit according to the embodiment shown in FIG. 3 includes a high selection section 10, a row selection section 11, a high transfer section 20, a row transfer section 21 and a reset section 30.

Here, the high data signal VHD, which is turned on by the high selection signal G1b (n) and applied to the data line DL, is transmitted to one side of the first storage capacitor C S1 , The row data signal VLD which is turned on by the row select signal G1 (n) and applied to the data line DL is transferred to one side of the first storage capacitor C S1 .

In addition, the high transmission portion 20 is connected to one side of the first storage capacitor (C S1), is turned on by the high-pass signal 11 is a voltage that is stored on one side of the first storage capacitor (C S1) Is connected to one side of the liquid crystal capacitor C LC and connected to one side of the first storage capacitor C S1 and is turned on by the low transfer signal G2 and stored on one side of the first storage capacitor C S1 And transmits a voltage to one side of the liquid crystal capacitor C LC and one side of the second storage capacitor C S2 .

The reset unit 30 is connected to one side of the liquid crystal capacitor C LC and one side of the second storage capacitor C S2 and is turned on by the reset signal RES to turn on one side of the liquid crystal capacitor C LC One side of the liquid crystal capacitor C LC is reset to the intermediate voltage V center by transferring the intermediate voltage to one side of the second storage capacitor C S2 . Here, the common voltage V COM is applied to the other side of the liquid crystal capacitor C LC , the other side of the first storage capacitor C S1 , and the other side of the second storage capacitor C S2 .

The high select unit 10 and the high transfer unit 20 may be PMOS transistors and the row select unit 11, the row transfer unit 21, (NMOS) transistors.

The pixel circuit according to the embodiment shown in FIG. 4 includes a high selection section 40, a row selection section 41, a high transfer section 50, and a low transfer section 51. Here, the high selection unit 40 outputs the high data signal VDH and the common voltage Vcom, which are turned on by the high selection signal G1b (n) and applied to the high data line DH, to the storage capacitor Cs And the row selection unit 41 selects either the row data signal VDL applied to the row data line DL or the common voltage Vcom by turning on the row selection signal G1 (n) To the other side of the capacitor Cs.

The high transfer unit 50 is connected to one side of the storage capacitor Cs and is turned on by the high transfer signal G2b to supply a voltage stored in one side of the storage capacitor Cs to the liquid crystal capacitor C LC Or transmits the high data signal VDH or the common voltage Vcom to one side of the liquid crystal capacitor C LC by the high selection unit 40 and supplies the high data signal VDH and the common voltage Vcom to one side of the low transfer unit 51 is connected to the other side of the storage capacitor Cs and supplies a voltage that is turned on by the low transfer signal G2 and stored in the other side of the storage capacitor Cs to one side of the liquid crystal capacitor C LC Or transmits the row data signal VDL or the common voltage Vcom transmitted to the row selection unit 41 to one side of the liquid crystal capacitor C LC . Here, the common voltage Vcom is applied to the other side of the liquid crystal capacitor C LC .

Specifically, the high selection unit 40 and the high transfer unit 50 may be formed of a PMOS transistor, and the row selection unit 41 and the row transfer unit 51 may be formed of an NMOS transistor .

A Vcom modulation timing diagram when the pixel circuit shown in Fig. 4 is employed is shown in Fig. As shown in Fig. 5, since two different Vcom drivers are used to modulate each other at different times, the display validity time becomes longer as compared with the conventional structure using one Vcom driver.

In the field sequential color scheme, Vcom modulation may be driven differently depending on the structure of the pixel circuit. In a panel with pixels with two-stage storage, the display can also be turned on during the addressing period because the LC capacitor and the storage capacitor are separated. This has the advantage that the display validity time is longer than the method of directly transmitting data to the liquid crystal. To achieve Vcom modulation with the same effective display time in a two-stage storage pixel, Vcom must be split into two.

If Vcom is connected in the same way from the inside to the outside, the addressing period can not be maintained, and the addressing period is changed together with the Vcom change.

Hereinafter, the liquid crystal driving method and the liquid crystal response speed of the liquid crystal display device and the LCD driving device according to the present invention will be described with reference to FIGS. 6 to 9. FIG.

FIG. 6 is a view for explaining a first driving method of the liquid crystal display device according to the present invention, and shows a response waveform when overdriving using the fixed Vcom method. FIG. Fig. 5 is a diagram for explaining a driving method, and shows a response waveform in the case of overdriving using the fixed Vcom method. Fig. In the fixed Vcom method, data is applied in a state where the Vcom voltage is fixed, and the range of the applied voltage varies depending on the polarity.

8 is a view for explaining a third driving method of the liquid crystal display device according to the present invention, which shows a response waveform when overdriving by using the variable Vcom method, and Fig. 9 is a graph showing the response waveform of the liquid crystal display device according to the present invention Fig. 5 is a diagram for explaining the fourth drive system, and shows a response waveform when overdriving is performed using the variable Vcom system. The variable Vcom method is a method in which data is applied while varying the voltage Vcom according to the polarity. The range of the applied voltage according to the polarity is the same, and it can be designed with a low voltage, thereby reducing power consumption.

At this time, the response waveforms of Figs. 6 to 8 show the case where the liquid crystal display according to the present invention employs the pixel circuit shown in Fig. However, even when the pixel circuit shown in Fig. 3 or another field circuit is used, the same effect as that shown in Figs. 6 to 8 (improvement of liquid crystal response speed) can be achieved.

6, the first driver 161 is connected to a first electrode (not shown) connected to a capacitor provided in a unit pixel located on the driving substrate 111 of the liquid crystal panel 110 And controls the applied first voltage Vcom1. The first driver 161 may select one of the data signal and the first voltage Vcom1. The first driver 161 applies the modulated first voltage Vcom1_m before the pixel data voltage transfer and returns the voltage to the first voltage Vcom1 before modulation. That is, the instantaneously modulated first voltage Vcom1_m is applied for a very short time, for example, for a period of several tens to several hundreds of microseconds.

At this time, the second driver 162 controls the second voltage Vcom2 applied to the second electrode provided on the top plate 112 of the liquid crystal panel 110, and applies the second voltage Vcom2 having a constant size do.

On the other hand, the modulated first voltage Vcom1_m has a voltage value (Vcom1_mL) lower than the first voltage (Vcom1) before modulation in a negative field, and has a positive field Has a voltage value Vcom1_mH higher than the first voltage Vcom1 before modulation.

The polarity of the field, such as the negative field or the positive field, is divided according to the magnitude of the voltage applied with respect to the top plate electrode vcom. The negative field means a period in which a voltage inputted to the top plate electrode vcom is lower than vcom and a positive field means a period in which a voltage inputted to the top plate electrode vcom is higher than vcom. For example, when vcom is 6V, the input value of the positive field is about 6 to 12V, and the input value of the negative field is about 0 to 6V.

When the voltage is applied to only one of the electric fields due to the nature of the liquid crystal, image sticking remains on the screen. Thus, by changing the polarity of the liquid crystal every field, in other words, by changing the direction of the electric field every fixed time, the above problem can be solved.

In this manner, if the level of the first voltage Vcom1 is instantaneously modulated and restored before the pixel data voltage transfer (global transfer), the liquid crystal is operated in advance before applying the data to the liquid crystal, The response time is very fast as compared with the liquid crystal response (indicated by a dotted line) of the conventional liquid crystal display device.

Referring to the second embodiment shown in FIG. 7, the driver unit 160 implements overdriving using the second voltage Vcom2.

The second driver 162 controls the second voltage Vcom2 applied to the second electrode (not shown) provided on the top plate 112 of the liquid crystal panel 110. In the pixel data voltage transfer period (Global transfer) , The modulated second voltage (Vcom2_m) is applied to the second electrode, and is returned to the second voltage (Vcom2) before modulation. That is, the modulated second voltage Vcom2_m is applied momentarily for a very short time, for example, for several tens to several hundreds of microseconds.

At this time, the first driver 161 controls the first voltage Vcom1 applied to the first electrode (not shown) connected to the capacitor provided in the unit pixel located on the driving substrate 111 of the liquid crystal panel 110 , And applies a first voltage (Vcom1) of a constant size.

On the other hand, the modulated second voltage Vcom2_m has a voltage value Vcom2_mH higher than the second voltage Vcom2 before modulation in the negative field and a voltage value Vcom2_mL lower than the second voltage Vcom2 before modulation in the positive field, .

As described above, when the level of the second voltage Vcom2 is instantaneously changed and restored for a short time in the pixel data voltage transfer period (Global transfer), the liquid crystal response of the conventional liquid crystal display device Response time.

More specifically, since the response speed is determined according to the magnitude of the voltage applied to the liquid crystal, the level of the second voltage Vcom2 is temporarily set to a value in the direction in which the voltage applied to the liquid crystal increases in the pixel data voltage transfer , The liquid crystal reacts more quickly than the response speed to the voltage that is actually intended to be applied.

If the level of the second voltage Vcom2 that has been changed for a short period is returned to its original value, the molecules in the liquid crystal have already been activated a lot. Therefore, even if a lower voltage is sequentially applied, not.

If the first voltage Vcom1 and the second voltage Vcom2 are separately controlled using the two drivers 161 and 162 as described above, the stored value of the pixel circuit already applied to the liquid crystal and the newly stored pixel data voltage value are mixed And the stored value applied to the liquid crystal can be maintained until the initialization, so that the effective display time is greatly increased.

The third and fourth embodiments shown in Figs. 8 and 9 use the variable Vcom scheme. The first driver 161 sets the first voltage Vcom1 to a high level (VH And the second driver 162 alternately modulates the second voltage Vcom2 to the high level VH and the low level VL every time a liquid crystal reset is performed, And is driven in a modulating manner.

Referring to FIG. 8, the first driver applies the modulated first voltage Vcom1_m to the first electrode before transferring the pixel data voltage (Global Transfer), and then returns the voltage to the first voltage Vcom1 before modulation. That is, the momentarily modulated first voltage Vcom1_m is applied.

The modulated first voltage Vcom1_m has a voltage value Vcom1_mL lower than the first voltage Vcom1 before modulation in the negative field and a voltage value Vcom1_mH higher than the first voltage Vcom1 before modulation in the positive field. Lt; / RTI >

In this way, if the level of the first voltage Vcom1 is instantaneously changed and restored before the pixel data voltage transfer (global transfer), the liquid crystal reacts more quickly by operating the liquid crystal in advance before applying the data to the liquid crystal. That is, the response time is very fast compared with the liquid crystal response (indicated by the dotted line) of the conventional liquid crystal display device.

Referring to FIG. 9, the second driver 162 applies the modulated second voltage Vcom2_m to the second electrode in the pixel data voltage transfer period (Global Transfer), and then applies the second voltage Vcom2 ).

The modulated second voltage Vcom2_m has a voltage value Vcom2_mH that is higher than the second voltage Vcom2 before modulation in the negative field and a voltage value Vcom2_mL that is lower than the second voltage Vcom2 before modulation in the positive field .

As described above, when the level of the second voltage Vcom2 is instantaneously changed and restored for a short time in the pixel data voltage transfer period (Global transfer), the liquid crystal response of the conventional liquid crystal display device It has response time.

More specifically, since the response speed is determined according to the magnitude of the voltage applied to the liquid crystal, the level of the second voltage Vcom2 is temporarily changed in the direction in which the voltage applied to the liquid crystal increases in the pixel data voltage transfer , The liquid crystal reacts faster than the response speed to the voltage that was actually being applied.

If the level of the second voltage Vcom2 that has been changed for a short period is returned to its original value, the molecules in the liquid crystal have already moved a great deal. Therefore, even if a lower voltage is continuously applied, the liquid crystal response speed is very fast .

At this time, the timing control unit 140 may adjust the time for modulating the first voltage Vcom1 and the second voltage Vcom2. In another embodiment, modulation of the modulation time may be made in an external controller (not shown).

The driver unit 160 including the first driver 161 and the second driver 162 for performing the operations described above may be implemented as an LCD driver . Of course, the LCD driving apparatus according to the present invention may further include components such as the data driver 130, the gate driver 120, and the timing controller 140, in addition to the driver unit 160.

According to the LCD driving device and the liquid crystal display device 100 including the LCD driving device according to the present invention, the response speed of the liquid crystal can be remarkably improved without using a lookup table, a memory, etc., It is possible to improve the brightness by eliminating the color mixing between colors of R, G and B, increasing the effective response time of the display, and improving the flicker of the screen by implementing a high frame rate. That is, the liquid crystal display device 100 using the field sequential color system exhibits a very excellent effect.

Meanwhile, the liquid crystal display device 100 described above may have a different structure depending on the driving method, one or more components may be omitted, or one or more components may be added. Further, two or more components may be integrated into one component, or one component may be implemented by being separated into two or more components. It will be apparent to those skilled in the art that the function or operation of each component described above can be accomplished in a different manner in liquid crystal displays of different driving methods.

While the foregoing description and accompanying drawings illustrate possible embodiments of the invention, the scope of the invention is defined only by the appended claims. In addition, it will be apparent to those skilled in the art that various changes in form and detail may be made therein without departing from the basic principles of the invention, which will be apparent to those skilled in the art.

100 ......... .. liquid crystal display
110 ......... .. liquid crystal panel
120 ... Gate driver
130, ...,
140 ... Timing control unit
150 ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Backlight unit
160 ......... driver unit
161 .......... First driver
162 ... second driver

Claims (21)

A first driver for controlling a first voltage (Vcom1) applied to a first electrode connected to a capacitor provided in a unit pixel located on a driving substrate of a liquid crystal panel; And
And a second driver for controlling a second voltage (Vcom2) applied to a second electrode of the upper panel of the liquid crystal panel,
The first voltage Vcom1 and the second voltage Vcom2 are individually controlled by the first driver and the second driver,
The first driver alternately modulates the first voltage (Vcom1) to a high level (VH) and a low level (VL) before an address of a new data,
The second driver alternately modulates the second voltage (Vcom2) to a high level (VH) and a low level (VL) each time a liquid crystal reset (Global Reset) is performed. delete delete delete delete delete The method according to claim 1,
The first driver applies a first voltage (Vcom1_m) modulated to the first electrode before the pixel data voltage transfer (Global Transfer), and then returns the voltage to the first voltage (Vcom1) before modulation. 8. The method of claim 7,
The modulated first voltage Vcom1_m has a voltage value Vcom1_mL lower than the first voltage Vcom1 before modulation in the negative field and a first voltage Vcom1 before modulation in the positive field, And has a higher voltage value (Vcom1_mH). The method according to claim 1,
The second driver is an LCD driver for applying a modulated second voltage (Vcom2_m) to the second electrode in the pixel data voltage transfer period (Global Transfer) and then returning the second voltage (Vcom2_m) . 10. The method of claim 9,
The modulated second voltage Vcom2_m has a voltage value Vcom2_mH higher than the unmodulated second voltage Vcom2 in the negative field and a second voltage Vcom2 before modulation in the positive field, And has a lower voltage value (Vcom2_mL). A liquid crystal display device comprising a liquid crystal panel and a backlight unit,
A first electrode connected to a capacitor provided in a unit pixel located on a driving substrate of the liquid crystal panel;
A second electrode provided on the upper plate of the liquid crystal panel;
A first driver for controlling a first voltage (Vcom1) applied to the first electrode; And
And a second driver for controlling a second voltage (Vcom2) applied to the second electrode,
The first voltage Vcom1 and the second voltage Vcom2 are individually controlled by the first driver and the second driver,
The first driver alternately modulates the first voltage (Vcom1) to a high level (VH) and a low level (VL) before an address of a new data,
The second driver alternately modulates the second voltage (Vcom2) to a high level (VH) and a low level (VL) each time a liquid crystal reset (Global Reset) is performed. delete delete delete delete delete 12. The method of claim 11,
The first driver applies a first voltage (Vcom1_m) modulated before the pixel data voltage transfer (Global Transfer) to the first electrode, and then applies a first voltage (Vcom1) before modulation. 18. The method of claim 17,
The modulated first voltage Vcom1_m has a voltage value Vcom1_mL lower than the first voltage Vcom1 before modulation in the negative field and a first voltage Vcom1 before modulation in the positive field, And has a higher voltage value (Vcom1_mH). 12. The method of claim 11,
The second driver applies a second voltage (Vcom2) before modulating the second voltage (Vcom2_m) to the second electrode in the pixel data voltage transfer period (Global transfer) . 20. The method of claim 19,
The modulated second voltage Vcom2_m has a voltage value Vcom2_mH higher than the unmodulated second voltage Vcom2 in the negative field and a second voltage Vcom2 before modulation in the positive field, And has a lower voltage value (Vcom2_mL). 12. The method of claim 11,
Wherein the liquid crystal display device drives the backlight unit in a field sequential color (FSC) manner.
KR1020160027686A 2016-03-08 2016-03-08 Liquid crystal display driving device and liquid crystal display using the same KR101837143B1 (en)

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Publication number Priority date Publication date Assignee Title
JP2011142643A (en) * 2006-12-13 2011-07-21 Panasonic Corp Drive voltage control device
KR101562215B1 (en) * 2014-05-08 2015-10-23 주식회사 라온텍 Circuit for Driving Liquid Crystal Display

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011142643A (en) * 2006-12-13 2011-07-21 Panasonic Corp Drive voltage control device
KR101562215B1 (en) * 2014-05-08 2015-10-23 주식회사 라온텍 Circuit for Driving Liquid Crystal Display

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