KR20070116512A - Liquid crystal display and driving method thereof - Google Patents

Abstract

An LCD device and a driving method thereof are provided to enhance display quality by inserting white patterns in an FSC(Field Sequential Color) operation scheme. An LCD(Liquid Crystal Display) device includes a liquid crystal panel(106), first, second, and third light sources(134a,134b,134c), and a beam driver(176). The first, second, and third light sources radiate beams to the liquid crystal panel. The beam driver sequentially drives the first, second, and third light sources during a frame. The beam driver radiate white beams to the liquid crystal panel during one of predetermined periods after illumination period of the second light source, the third light source, and the second and third light sources.

Description

Liquid Crystal Display And Driving Method Thereof

1 is a diagram for explaining conventional field sequential color driving;

FIG. 2 is a view for explaining a CBU (Color Break Up) phenomenon occurring when driving a conventional field sequential color; FIG.

3 is a perspective view showing a liquid crystal display module of the liquid crystal display according to the embodiment of the present invention.

4 is a cross-sectional view taken along the line II-II 'of FIG.

5 is a diagram for explaining sequential color driving according to an embodiment of the present invention;

6 is a schematic plan view showing a liquid crystal display device having a separate white LED array for inserting a white pattern according to an embodiment of the present invention.

7 is a block diagram illustrating a driving device for driving a liquid crystal display device according to an exemplary embodiment of the present invention.

<Description of Major Symbols in Drawing>

100: liquid crystal display module 102: top case

103: lower substrate 105: upper substrate

106: liquid crystal panel 108: optical sheet

110: diffuser plate 112: reflector plate

130: LED array 132: PCB

134: Multiple LED 170: Timing Controller

172: data driving circuit 174: gate driving circuit

176: light source driving circuit 178: power generating unit

AP: Data write time (TFT scan time) WP: LCD response time

FP: Backlight emission time WPI: White pattern inserted

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a driving method thereof, and more particularly to a liquid crystal display device and a driving method thereof capable of improving display quality by inserting a white pattern in an FSC driving method to prevent CBU (Color Break Up). .

Typically, a liquid crystal display (LCD) is a plurality of liquid crystal cells arranged in a matrix form and a plurality of control switches for switching a video signal to be supplied to each of these liquid crystal cells. The amount of light transmitted from the backlight unit is adjusted by the configured liquid crystal panel to display a desired image on the screen.

As a lamp used in the backlight unit, a cold cathode fluorescent lamp (hereinafter referred to as 'CCFL') is mainly used. The backlight unit using the CCFL includes a lamp for generating light, a lamp housing installed in a form surrounding the lamp, a light guide plate for converting light incident from the lamp into a planar light source, a lower surface of the light guide plate under the light guide plate, A reflecting plate for reflecting the light propagating toward the upper surface toward the upper surface, a first diffusion sheet for diffusing light through the light guide plate, a first and second prism sheets for adjusting the propagation direction of the light passing through the first diffusion sheet, and a prism And a second diffusion sheet for diffusing light via the sheet.

Such backlight units are in the trend of miniaturization, thinning, and weight reduction. In accordance with this trend, light emitting diodes (LEDs), which are advantageous in power consumption, weight, and brightness, have been proposed instead of CCFLs used in backlight units. In addition, the backlight unit uses a field sequential color (FSC) driving method to obtain good image quality.

In the FSC driving method, as shown in FIG. 1, the entire frame (1 frame = 16.7 ms) on the panel is divided into three subframes of red (R), green (G), and blue (B). That is, the FSC driving method sequentially displays the R, G, and B screens in chronological order, thereby displaying the screen using the temporal integration effect of the eyes on the three primary colors of light. Here, each subframe is divided into a data writing time (TFT scan time) AP, a liquid crystal response time WP, and a backlight emission time FP. As a result, the time FP for turning on the backlight according to each color is the time excluding the data writing time AP and the liquid crystal response time WP.

By the way, as shown in FIG. 2, the FSC driving method divides three primary colors (R, G, and B) of colors spatially within a range smaller than the resolution of a conventional eye, and displays the colors using a combination of these colors. CBU (Color Break Up) phenomenon is more prominent than the driving method. That is, in the FSC driving method, since R, G, and B are sequentially driven within one frame, when the viewer moves left and right as shown in FIG. 2, the screen looks like a rainbow. The main reason for this phenomenon is that, for example, when the G signal is applied after the R signal is applied, the center of the human retina shows a habit of moving in the direction in which the object moves. As a result, R, G formed on the retina is caused. This is because the position of.

Accordingly, an object of the present invention is to provide a liquid crystal display device and a driving method thereof which can improve display quality by inserting a white pattern in an FSC driving method to prevent a CBU (Color Break Up) phenomenon.

In order to achieve the above object, a liquid crystal display device according to an embodiment of the present invention comprises a liquid crystal panel; A plurality of first color light sources, second color light sources, and third color light sources for irradiating light onto the liquid crystal panel; And a light source driving circuit for sequentially driving the plurality of first to third color light sources within one frame; The light source driving circuit includes any one of a predetermined period after the lighting period of the second color light source, a predetermined period after the lighting period of the third color light source, and a predetermined period after the lighting period of the second and third color light sources. White light is irradiated onto the liquid crystal panel for a period of time.

The light source driving circuit simultaneously drives the plurality of first color light sources, the second color light sources, and the third color light sources during the predetermined period.

The first to third color light sources are any one of red, green, and blue light sources, respectively.

The liquid crystal display according to the present invention further comprises a plurality of white light sources for generating the white light; The light source driving circuit drives the plurality of white light sources during the predetermined period.

In addition, the method of driving a liquid crystal display device comprising a liquid crystal panel according to the present invention, a plurality of second color light sources, a second color light source, and a third color light source for irradiating light to the liquid crystal panel. Sequentially driving the first to third color light sources within one frame; And the predetermined period after the lighting period of the second color light source, the predetermined period after the lighting period of the third color light source, and the predetermined period after the lighting period of the second color and third color light sources. Irradiating white light with the liquid crystal panel.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 3 to 7.

3 is a perspective view illustrating a liquid crystal display module of the liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view of the liquid crystal display module illustrated in FIG. 3 taken along the line II-II ′.

3 and 4, the liquid crystal display module 100 of the liquid crystal display according to the exemplary embodiment of the present invention includes a support main 114 and a backlight unit and a liquid crystal panel stacked inside the support main 114. 106 and a top case 102 for wrapping the edge of the liquid crystal panel 106 and the side surface of the support main 114.

The liquid crystal panel 106 includes a spacer (not shown) for injecting liquid crystal between the upper substrate 105 and the lower substrate 103 and for maintaining a constant gap between the upper substrate 105 and the lower substrate 103. . The common electrode, not shown, is formed on the upper substrate 105 of the liquid crystal panel 106. In addition, signal lines such as data lines and gate lines (not shown) are formed on the lower substrate 103 of the liquid crystal panel 106, and thin film transistors ("TFTs") at the intersections of the data lines and the gate lines. Is formed. The TFT switches the data signal to be transmitted from the data line toward the liquid crystal cell in response to the scan signal (gate pulse) from the gate line. The pixel electrode is formed in the pixel region between the data line and the gate line. In addition, a pad region for connecting data lines and gate lines, respectively, is formed at one side of the lower substrate 103, and a tape carrier (not shown) in which a driver integrated circuit for applying a driving signal to a TFT is mounted on the pad region. The package (Tape Carrier Package) is attached. This tape carrier package supplies data signals to the data lines from the driver integrated circuit. The scan signal is also supplied to the gate lines. The upper polarizing sheet is attached to the upper substrate 105 of the liquid crystal panel 106, and the lower polarizing sheet is attached to the rear surface of the lower substrate 103.

The liquid crystal panel 106 of the liquid crystal display device according to the embodiment of the present invention improves the productivity of the liquid crystal display device by eliminating the color filter formed on the liquid crystal panel 106 of the general liquid crystal display device, and the light of the color filter. The luminance may be improved by eliminating a phenomenon in which light transmittance is lowered due to absorption.

The support main 114 is a mold, and the side wall surface therein is formed into a stepped stepped surface, and the stepped surface is formed with a seating portion on which the plurality of optical sheets 108 are seated. Inside the support main 114, a backlight unit for irradiating light to the liquid crystal panel 106 and a liquid crystal panel 106 are stacked.

The backlight unit includes a plurality of LED arrays 130 including a plurality of light emitting diodes (“LEDs”) 134 for irradiating light to the liquid crystal panel 106, and a plurality of LEDs 134. The diffusion plate 110 for diffusing the light incident from the light to the liquid crystal panel 106, the reflection sheet 112 disposed on the rear surface of the plurality of LED arrays 130, and the diffusion plate 110. Consisting of a plurality of optical sheets 108.

The plurality of LED arrays 130 are printed circuit boards in which a plurality of LEDs 134 for generating light and a circuit for controlling light emission of the plurality of LEDs 134 are mounted, as shown in part “A”. Circuit Board: hereinafter referred to as "PCB" (132). Here, the "A" part is an artificially protruding part to show the LED array 130 in detail. LED 132 emits a unique color light (e.g. red, green and blue) as a point light source. The PCB 132 supports the LED 134 and controls the light emission of the LED 134 by a circuit configured therein. Light generated by the LED 134 is incident on the diffuser plate 110. The light propagated to the lower surface of the LED array 130 is reflected by the reflecting sheet 112 and proceeds toward the diffuser plate 110.

The diffusion plate 110 directs the light incident from the plurality of LEDs 134 emitting red, green, and blue unique color light toward the front direction of the liquid crystal panel 106, and diffuses the light so that the light is uniform in a wide range. The diffused light is irradiated onto the liquid crystal panel 106 to have a distribution. The diffusion plate 110 is used to coat the light diffusion member on both sides of the film made of a transparent resin.

The reflective sheet 112 is disposed on the back of the plurality of LED arrays 130. The reflective sheet 112 is formed of a material that reflects light to reflect the light traveling toward the rear surface of the plurality of LED arrays 130 toward the liquid crystal panel 106 to improve the efficiency of the light irradiated onto the liquid crystal panel 106.

Light emitted through the diffusion plate 110 is incident on the liquid crystal panel 106 via the plurality of optical sheets 108. The light emitted from the diffuser plate 110 is formed with diffused light so that a viewing angle is large. When the light incident on the liquid crystal panel 106 is vertical, the light efficiency is increased. To this end, a plurality of optical sheets 108 are disposed on the diffuser plate 110.

The plurality of optical sheets 108 concentrate light emitted from the diffuser plate 110 vertically to improve light efficiency. Accordingly, the light emitted from the diffuser plate 110 is incident on the liquid crystal panel 106 via the plurality of optical sheets 108.

The top case 102 is manufactured in the form of a square strip having a flat portion and a side portion bent at a right angle. The top case 102 surrounds the edge of the liquid crystal panel 106 and the support main 114.

As such, the liquid crystal display module 100 employing the three color light sources of the red LED 134a, the green LED 134b, and the blue LED 134c has the color filter removed, and the red LED 134a, the green LED 134b, and the blue color. It is driven by the FSC system which sequentially flashes the tricolor light source of the LED 134c.

As shown in FIG. 1, the liquid crystal display module 100 driven by the FSC method charges red data into the liquid crystal cell during the scan time AP of the TFT, and then after the response time WP of the liquid crystal has passed. The red LED 134c is turned on to display red color for a period FP shorter than the? Frame period. After the red is displayed, green and blue are displayed by writing green data and lighting of the green LED 134b, followed by writing of blue data and lighting of the blue LED 134c.

In detail, the liquid crystal display module 100 for displaying an image by driving the tricolor light sources of the red LED 134a, the green LED 134b, and the blue LED 134c of the backlight unit in the FSC method displays liquid crystals for one frame period. It is driven by dividing the response time and the lighting time of the LEDs (134a, 134b, 134c). When the red LED 134a is turned on for a time shorter than the frame period, a corresponding image is displayed on the liquid crystal panel 106 by the emitted red light. After that, when the red LED 134a is turned off and the green LED 134b is turned on for a time shorter than the ⅓ frame period, a corresponding image is displayed on the liquid crystal panel 106 by the emitted green light. After that, when the green LED 134b is turned off and the blue LED 134c is turned on for a time shorter than a ⅓ frame period, a corresponding image is displayed on the liquid crystal panel 106 by the emitted blue light. Through this driving method, all three color light sources of the red LED 134a, the green LED 134b, and the blue LED 134c are turned on for one frame period, so that the original image to be displayed is displayed on the liquid crystal panel 106.

In this case, in order to prevent the CBU phenomenon that is a problem in the FSC driving method, a white pattern is inserted after the lighting period of the green LED 134b and the lighting period of the blue LED 134c in the present invention. This will be described later with reference to FIG. 5.

5 is a view showing a white pattern in which tricolor light is turned on and inserted in one frame period in the liquid crystal display according to the present invention.

As shown in FIG. 5, the liquid crystal display according to the present invention has a lighting period (FP (G)) of the green LED 134b and a writing period (AP (B)) of the blue data in order to prevent a CBU phenomenon during FSC driving. Insert a white pattern (WPI) in between. Further, the liquid crystal display according to the present invention inserts the white pattern WPI between the lighting period FP (B) of the blue LED 134c and the writing period AP (R) of the red data. As described above, when the white pattern WPI is inserted after the green LED 134b or the blue LED 134c is turned on, the position difference between the red LED-green LED and the green LED-blue LED formed in the observer's retina is inserted white. The pattern (WPI) makes it invisible to the observer.

This white pattern WPI is obtained by simultaneously lighting the red, green, and blue LEDs 134a, 134b, 134c during the white pattern WPI application period after the green LED 134b or the blue LED 134c is turned on. .

Meanwhile, as shown in FIG. 6, the white pattern WPI is formed by the white pattern by the backlight unit 160 for driving white, which is additionally provided in addition to the backlight unit 150 for driving red, green, and blue. WPI) may be obtained by turning on the white LED during the application period. As such, the reason for including the backlight unit 160 for driving white separately is to obtain a white pattern by using the red, green, and blue LEDs 134a, 134b, and 134c. This is because there is a problem in time margin because three LEDs must be turned on at the same time.

Here, in the exemplary embodiment of the present invention, only one case of sequentially driving one frame in order of red LED → green LED → blue LED has been described by way of example, but the technical idea of the present invention is not limited thereto. That is, the driving order of the three colors of LEDs may be set differently, and in this case, the white pattern WPI may be inserted for a predetermined period after the light emitting period of the second emitting LED and / or a predetermined period following the light emitting period of the third emitting LED. do.

7 is a view showing a driving device for driving a liquid crystal display module according to the present invention.

Referring to FIG. 7, in the liquid crystal display according to the exemplary embodiment of the present invention, the data lines D1 to Dm and the gate lines G1 to Gn cross each other to drive the liquid crystal cell Clc formed at an intersection thereof. A liquid crystal panel 106 having TFTs formed therein, a data driving circuit 172 for supplying data to the data lines D1 to Dm of the liquid crystal panel 106, and gate lines G1 of the liquid crystal panel 106. A gate driving circuit 174 for supplying scan pulses to ˜Gn, a plurality of red LEDs 134a, green LEDs 134b, and blue LEDs 134c for irradiating light to the liquid crystal panel 106; A light source driving circuit 176 for sequentially driving the plurality of red LEDs 134a, green LEDs 134b, and blue LEDs 134c, a data driving circuit 172, a gate driving circuit 174, and a light source driving circuit. To control 176, fill in timing controller 170, liquid crystal panel 106, data driver circuit 172, gate driver circuit 174, and light source driver circuit 176. A power generator 178 for supplying required power is provided.

In the liquid crystal panel 106, liquid crystal is injected between two glass substrates. The TFTs formed at the intersections of the data lines D1 to Dm and the gate lines G1 to Gn of the liquid crystal panel 102 are in response to the scanning pulses from the gate driving circuit 174. ) Is supplied to the liquid crystal cell (Clc). For this purpose, the gate electrode of the TFT is connected to the gate lines G1 to Gn, and the source electrode is connected to the data lines D1 to Dm. The drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc. In each liquid crystal cell Clc of the liquid crystal panel 106, a storage capacitor Cst is formed to maintain a constant voltage charged in the liquid crystal cell Clc.

After the data driving circuit 172 samples the data according to the data control signal DDC from the timing controller 170, the data driving circuit 172 latches the sampled data by one line, and latches the latched data to the data lines D1 to Dm. Supply. In addition, the data driving circuit 172 may analogize the digital pixel data R ′, G ′, and B ′ from the timing controller 170 by using the gamma voltages GMA1 to 6 input from the power generator 178. The gamma voltage is converted and supplied to the data lines D1 to Dm.

The gate driving circuit 174 may include a shift register for sequentially generating gate pulses in response to a gate start pulse GSP among the gate control signals GDC from the timing controller 170, and a voltage of the gate pulses to the liquid crystal cell Clc. A level shifter for shifting to a voltage level suitable for driving. The gate driving circuit 174 sequentially supplies the gate high voltage Vgh and the gate low voltage Vgl to the gate lines G1 to Gn in response to the gate control signal GDC.

The plurality of LEDs 134 sequentially flash under the control of the light source driving circuit 176 to generate unique color light. The color lights generated from the plurality of LEDs 134 are irradiated to the liquid crystal panel 106 via a diffuser plate and a plurality of optical sheets which are not shown.

The light source driving circuit 176 sequentially drives the plurality of LEDs 134 in response to the light source control signal FMC from the timing controller 170. In order to insert the white pattern (WPI) using the backlight unit for driving the existing red, green, and blue, the light source driving circuit 176 turns red, green, and blue LEDs at the same time during the white pattern (WPI) application period. To be on. On the other hand, when using a backlight unit for driving a separate white, the light source driving circuit 176 causes the white LED to be turned on during the white pattern (WPI) application period. The light source driving circuit 176 receives the light source driving voltage Vinv from the power generator 178 to drive the plurality of LEDs 134.

The timing controller 170 generates a light source control signal FMC to control the light source, and supplies the light source control signal FMC to the light source driving circuit 176, and inputs the horizontal and vertical synchronization signals H and V and the clock signal CLK. ) Generates a data control signal DDC for controlling the data driving circuit 172 and a gate control signal GDC for controlling the gate driving circuit 174. The data control signal (DDC) includes a source start pulse (SSP), a source shift clock (SSC), a source output signal (SOE), a dot clock (Dclk), and a polarity inversion signal ( Polarity (POL) and the like are supplied to the data driving circuit 172. The gate control signal GDC includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output signal (GOE), and the like to the gate driving circuit 106. Supplied.

The power generator 178 includes the common electrode voltage Vcom on the liquid crystal display panel 106, the gamma voltage GMA1 to 6 on the data driver 172, the gate high voltage Vgh on the gate driver 174, and the gate low. The voltage Vgl and the light source driving voltage Vinv are supplied to the light source driver 176.

As described above, the LCD and the driving method thereof according to the present invention can improve the display quality by preventing the CBU (Color Break Up) by inserting a white pattern in the FSC driving method.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (5)

A liquid crystal panel; A plurality of first color light sources, second color light sources, and third color light sources for irradiating light onto the liquid crystal panel; And A light source driving circuit for sequentially driving the plurality of first to third color light sources within one frame; The light source driving circuit includes any one of a predetermined period after the lighting period of the second color light source, a predetermined period after the lighting period of the third color light source, and a predetermined period after the lighting period of the second and third color light sources. And white light is irradiated onto the liquid crystal panel for a period of time. The method of claim 1, And the light source driving circuit simultaneously drives the plurality of first color light sources, the second color light sources, and the third color light sources for the predetermined period of time. The method of claim 2, And the first to third color light sources are any one of red, green, and blue light sources. The method of claim 1, A plurality of white light sources for generating said white light; And the light source driving circuit drives the plurality of white light sources during the predetermined period. In the method of driving a liquid crystal display device comprising a liquid crystal panel, a plurality of second color light sources, a second color light source and a third color light source for irradiating light to the liquid crystal panel, Sequentially driving the plurality of first to third color light sources within one frame; And The liquid crystal during any one of a predetermined period after the lighting period of the second color light source, a predetermined period after the lighting period of the third color light source, and a predetermined period after the lighting period of the second color and third color light sources. And irradiating white light to the panel.

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