KR100536205B1 - Liquid crystal display device and driving method thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display and a driving method thereof.

According to the present invention, a plurality of light emitting diodes included in different chips are included, and each light emitting diode included in the same chip is connected to a first terminal of a light emitting controller in common, and emits the same color and is included in another chip. Connected to the second terminal of the light emitting controller in common.

Through this, the number of pins (terminals) of the light source controller can be further reduced, and the area of the light source controller can be further reduced.

Description

Liquid crystal display and its driving method {LIQUID CRYSTAL DISPLAY DEVICE AND DRIVING METHOD THEREOF}

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 having a field sequential driving method and a driving method thereof.

Recently, display devices are also required to be lighter and thinner in accordance with the light weight and thickness of personal computers and televisions, and according to such demands, flat displays such as liquid crystal displays (LCDs) instead of cathode ray tubes (CRTs) are required. Panel-type displays are being developed.

An LCD applies an electric field to a liquid crystal material having an anisotropic dielectric constant injected between two substrates, and adjusts the intensity of the electric field to control the amount of light transmitted to the substrate from an external light source (backlight). A display device for obtaining an image signal.

Such LCDs are typical of portable flat panel displays, and among them, TFT-LCD using a thin film transistor (TFT) as a switching element is mainly used.

In the TFT-LCD, each pixel may be modeled as a capacitor having a liquid crystal as a dielectric, that is, a liquid crystal capacitor. The equivalent circuit of each pixel in the LCD is shown in FIG.

As illustrated in FIG. 1, each pixel of the liquid crystal display includes a TFT 10 having a source electrode and a gate electrode connected to the data line Dm and the scan line Sn, respectively, and a drain electrode and a common voltage Vcom of the TFT. It includes a liquid crystal capacitor (Cl) connected between and a storage capacitor (Cst) connected to the drain electrode of the TFT.

In Fig. 1, when the scan signal is applied to the scan line Sn and the TFT 10 is turned on, the data voltage Vd supplied to the data line is applied to each pixel electrode (not shown) through the TFT. Then, an electric field corresponding to the difference between the pixel voltage Vp and the common voltage Vcom applied to the pixel electrode is applied to the liquid crystal (equivalently represented by the liquid crystal capacitor in FIG. 1), and thus transmittance corresponding to the intensity of the electric field. To allow light to pass through. At this time, the pixel voltage Vp should be maintained for one frame or one field. In FIG. 1, the storage capacitor Cst is used to maintain the pixel voltage Vp applied to the pixel electrode.

In general, the liquid crystal display may be divided into two methods, a color filter method and a field sequential driving method, according to a method of displaying a color image.

A color filter type liquid crystal display device forms a color filter layer composed of three primary colors of red (R), green (G), and blue (B) on one of two substrates, and transmits the amount transmitted through the color filter layer. Display the desired color by adjusting. The color filter type LCD synthesizes R, G, and B colors by adjusting the amount of light transmitted through the R, G, and B color filter layers to transmit light emitted from a single light source to the R, G, and B color filter layers. Thereby displaying the desired color.

As described above, in a liquid crystal display device displaying a color using a single light source and a three-color color filter layer, a corresponding unit pixel is required for each of the R, G, and B regions, so that three times as many pixels are used as for displaying black and white. It is necessary. Therefore, in order to obtain a high resolution image, sophisticated manufacturing technology of a liquid crystal display panel is required.

In addition, there is a manufacturing problem that a separate color filter layer must be formed on the liquid crystal display substrate, and there is a problem that the light transmittance of the color filter itself must be improved.

The liquid crystal display of the field sequential driving method periodically turns on independent light sources of R, G, and B colors, and applies a color signal corresponding to each pixel in synchronism with the lighting cycle to display a full color image. Get it. That is, according to the liquid crystal display of the field sequential driving method, R, G, and B primary colors output from R, G, and B backlights to one pixel are not divided into R, G, and B pixel units. By displaying the light sequentially in time division, a color image is displayed using the afterimage effect of the eye.

The field sequential driving method can be classified into an analog driving method and a digital driving method.

The analog driving method sets a plurality of gray voltages corresponding to the number of gray scales to be displayed, selects one gray voltage corresponding to gray data among the gray voltages, and drives the liquid crystal panel with the selected gray voltage, thereby applying the applied gray voltage. Gradation display is performed with the amount of transmitted light corresponding to.

2 is a diagram illustrating a driving voltage and a transmitted light amount according to a conventional LCD driving apparatus. In FIG. 2, the driving voltage refers to a voltage applied to the liquid crystal and the optical tranmittance refers to a transmission ratio with respect to the applied light when light is applied to the liquid crystal. That is, the light transmittance refers to the degree of twist that the liquid crystal can transmit light.

Referring to FIG. 2, in the R field section Tr for displaying the R color, a driving voltage of the V11 level is applied to the liquid crystal so that light corresponding to the driving voltage of the V11 level passes through the liquid crystal. In the G field section Tg for displaying the G color, a driving voltage of the V12 level is applied so that light corresponding to the driving voltage of the V12 level passes through the liquid crystal. Then, in the B field section Tb for displaying the B color, a driving voltage of the V13 level is applied to obtain a light transmittance corresponding to the driving voltage of the V13 level. The desired color image is displayed by the sum of the R, G, and B lights transmitted in the Tr, Tg, and Tb sections, respectively.

On the other hand, the digital driving method makes the driving voltage applied to the liquid crystal constant and controls the voltage application time to perform gradation display. According to this digital driving method, the gray scale is displayed by adjusting the accumulated amount of light transmitted through the liquid crystal by keeping the driving voltage constant and controlling the voltage applied state and the voltage unapplied state in a timely manner.

As described above, the field sequential method includes an R field section displaying an R color, a G field section displaying a G color, and a B field section displaying a B color. The G light emitting diode for emitting light and the B light emitting diode for emitting B light are sequentially turned on. Each of the light emitting diodes emits R, G, and B data to the liquid crystal to display a color image through accumulated light.

3 is a diagram illustrating a conventional light emitting diode for emitting R, G, and B light, and a fin structure for sequentially applying the same. In particular, FIG. 3 is a diagram illustrating the use of one or more light emitting diodes in order to increase luminance of each R, G, and B light.

As shown in FIG. 3, the conventional light source controller IC transmits control signals to two R light emitting diodes LED_R1 and LED_R2, G light emitting diodes LED_G1 and LED_G2, and B light emitting diodes LED_B1 and LED_B2, respectively. Allow each light emitting diode to be selected. Here, the two R light emitting diodes LED_R1 and LED_R2 are turned on at the same time and emit light, and then are turned on and emit light in the order of the two G light emitting diodes LED_G1 and LED_G2 and the B light emitting diodes LED_B1 and LED_B1. In order to select each of the light emitting diodes, as shown in FIG. 3, each of the light emitting diodes LED_R1, LED_R1... LED_B1, LED_B2 is connected to the light source controller with different pins. That is, the R light emitting diode LED_R1 is connected between the terminal VLEDR1 and the terminal R1_OUT to emit light by applying a voltage Vf to the R light emitting diode LED_R1. On the other hand, the R light emitting diode LED_R2 is selected by being connected to the terminal VLEDR1 and the terminal LED_R2 which are other terminals and applying a voltage Vf. In addition, each of the G light emitting diodes LED_G1 and LED_G2 and each of the B light emitting diodes LED_B1 and LED_B2 are connected to different pins and selected.

As such, the conventional light source controller is connected to each light emitting diode with different pins, and thus requires a large number of pins. In particular, when the number of light emitting diodes is further increased in order to increase the brightness, more pin counts are required. In the case of using such a large number of pins, not only the IC, which is a light source controller, becomes complicated, but also a problem of increasing the IC area occurs.

SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the above-described problems of the prior art, and to provide a liquid crystal display device that shares pins for controlling the same when a plurality of light emitting diodes for emitting the same light are used.

According to an aspect of the present invention,

Liquid crystal including a liquid crystal formed between the first substrate on which the first electrode is disposed and the second substrate on which the second electrode is disposed, and a light source controller for sequentially transmitting red, green, and blue light to one pixel. In a display device,

First, second, and third light emitters having a first terminal commonly connected to the first terminal of the light source controller to emit different colors;

A first terminal is connected to a second terminal of the light source controller, respectively, and a fourth light emitter emitting the same color as the first light emitter, a fifth light emitter emitting the same color as the second light emitter, and the same as the third light emitter. A sixth light emitter emitting color;

Second terminals of the first and fourth light emitters are commonly connected to a third terminal of the light source controller, second terminals of the second and fifth light emitters are commonly connected to a fourth terminal of the light source controller, The third terminal of the third and sixth light emitters may be connected in common to the fifth terminal of the light source controller. The first, second, and third light emitters are formed in the first chip, and the fourth, fifth, and sixth light emitters are formed in the second chip. The first terminal and the second terminal of the light source controller are terminals outputting a voltage for turning on the first to sixth light emitters, and the third terminal to the fifth terminal of the light source controller are the first to sixth light emitters. It is characterized in that the terminal for selecting a light emitter that emits the same color.

A method of driving a liquid crystal display according to another feature of the present invention is

In the method for driving the liquid crystal display device,

(a) turning on first to third terminals of the light source controller to emit light of the first and fourth light emitters in a first section;

(b) turning on the first terminal, the second terminal, and the fourth terminal of the light source controller to emit the second and fifth light emitters in the second section; And

(c) turning on the first terminal, the second terminal, and the fifth terminal of the light source controller to emit the third and six light emitters in the third section.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

Hereinafter, a liquid crystal display and a driving method thereof according to an exemplary embodiment of the present invention will be described with reference to FIGS. 4 to 6. The liquid crystal display according to the embodiment of the present invention is to generate R, G, B light through a plurality of R, G, B light emitting diodes, respectively, the liquid crystal display device sharing a pin between the light emitting diode and the device for controlling the same; It relates to the driving method.

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

As shown in FIG. 4, the liquid crystal display of the present invention includes a liquid crystal display panel 100, a scan driver 200, a data driver 300, a gray voltage generator 500, a timing controller 400, R, Light emitting diodes 600a, 600b, and 600c that output G and B light sources, respectively, and a light source controller 700.

A plurality of scan lines are formed on the liquid crystal display panel 100 to transmit a gate-on signal, and the plurality of scan lines are insulated from and intersect with the plurality of scan lines, and the data lines are configured to transmit gray data voltages and reset voltages corresponding to gray data. Formed. The plurality of pixels 110 arranged in a matrix form are surrounded by scan lines and data lines, respectively. Each pixel includes a thin film transistor (not shown) having a gate electrode and a source electrode connected to the scan and data lines, a pixel capacitor (not shown), and a storage capacitor (not shown) connected to the drain electrode of the thin film transistor. do.

The scan driver 200 sequentially applies a scan signal to the scan line, thereby turning on the TFT to which the gate electrode is connected to the scan line to which the scan signal is applied.

The timing controller 400 receives the gray level data signals R, G, and B data, the horizontal synchronization signal Hsync, and the vertical synchronization signal Vsync from an external or graphic controller (not shown), and controls necessary signals Sg, Sd and Sb are supplied to the scan driver 200, the data driver 300, and the light source controller 700, respectively, and the gray scale data R, G, and B DATA are supplied to the gray voltage generator 500.

The gray voltage generator 500 generates a gray voltage having a magnitude corresponding to gray data and supplies it to the data driver 300. The data driver 300 applies the gray voltage output by the gray voltage generator 500 to the data line.

The light emitting diodes 600a, 600b, and 600c respectively output light corresponding to R, G, and B to the LCD panel, and the light source controller 700 controls when the light emitting diodes 600a, 600b, and 600c are turned on. In the embodiment of the present invention, a light emitting diode is used as the backlight, but the present invention is not limited thereto.

Each of the light emitting diodes 600a, 600b, and 600c according to an embodiment of the present invention includes at least two light emitting diodes emitting light of the same color, and the light emitting diodes share the same color by pins connected to the light source controller. Light emitting diodes that emit light are simultaneously selected.

In this case, the timing at which the corresponding gray voltage is supplied from the data driver 300 to the data line and the timing at which the R, G, and B light emitting diodes are turned on by the light source controller 800 depend on the control signal provided by the timing controller 500. Can be motivated.

5 is a diagram illustrating a connection relationship between a light source controller 700 and a light emitting diode according to an exemplary embodiment of the present invention.

As shown in FIG. 5, the light source controller 700 according to an embodiment of the present invention includes two R light emitting diodes LED_R1 and LED_R2, two G light emitting diodes LED_G1 and LED_G2, and two light emitting diodes LED_B1 and LED_B2. ), The capacitor CLED1 and the capacitor CLED2 are connected. Here, the light emitting diodes LED_R1, LED_G1, and LED_B1 are formed in the first chip, which is one pack, and the light emitting diodes LED_R2, LED_G2, and LED_B2 are formed in the other second chip. In this case, in FIG. 5, each of the light emitting diodes emitting R, G, and B colors is configured as two, but is not limited thereto, and may include two or more light emitting diodes. The capacitors CLED1 and CLED2 are storage capacitors that store voltages to maintain light emission for each field (R, G, B field) when an applied voltage Vf is applied to each light emitting diode.

Referring to FIG. 5, the anode of the voltage applying pin (terminal) VLED1 and the light emitting diodes LED_R1, LED_G1, and LED_B1 are commonly connected, and the voltage applying pin (terminal) VLED2 and the light emitting diodes LED_R2, LED_G2, and LED_B2 are commonly connected to each other. ) Anodes are connected in common. In addition, the cathodes of the light emitting diodes LED_R1 and LED_R2 are commonly connected to the R selection pin (terminal) R_OUT, and the cathodes of the light emitting diodes LED_G1 and LED_G2 are commonly connected to the G selection pin G_OUT. The cathodes of the light emitting diodes LED_B1 and LED_B2 are commonly connected to the B select pin (terminal) B_OUT. In FIG. 5, the voltage applying pins VLED1 and VLED2 among the pins of the light source controller 700 are used to apply a voltage Vf for allowing each light emitting diode to emit light, and R, G, and B selection pins (terminals) ( R_OUT, G_OUT, B_OUT are applied with ON or OFF signal to select R light emitting diodes (LED_R1, LED_R2), G light emitting diodes (LED_G1, LED_G2) and B light emitting diodes (LED_B1, LED_B2) respectively. It is a pin (terminal). Here, the voltage is applied to the voltage applying pins (VLED1, VLED2) and selected through the selection pins (R_OUT, G_OUT, B_OUT) for each light emitting diode, but the voltage applying pins (VLED1, VLED2) using the light emitting diodes It can be used as a select pin and select pins (R_OUT, G_OUT, B_OUT) can be used as voltage applying pins.

As such, according to an embodiment of the present invention, the anodes of all light emitting diodes in the same chip are connected to one common pin (VLED1 or VLED2), emit the same color, and emit light emitting diodes in different chips. The cathode of (LED_R1-LED_R2, LED_G1-LED-G2, LED_B1-LED_B2) is also connected to one common pin (R_OUT, G_OUT, B_OUT_).

Hereinafter, a method in which each of the R, G, and B light emitting diodes having the connection relationship as shown in FIG. 5 is sequentially emitted will be described with reference to FIG. 6.

6 is a diagram illustrating a signal output to each pin of the light source controller in the connection relationship as shown in FIG. 5.

Referring to FIG. 6, the voltage applying pins VLED1 and VLED2 are always in an ON state when each LED emits light. In FIG. 6, although the ON states of the voltage applying pins VLED1 and VLED2 are all expressed by the same voltage for convenience, different voltages are actually applied as the voltage Vf for turning on each LED.

First, in the R field, the selection pin R_OUT is turned on while the voltage applying pins VLED1 and VLED2 are kept in the on state. Then, the voltage Vf is applied only to the light emitting diodes LED_R1 and LED_R2 to be turned on so that only the R light is output. That is, even when the voltage applying pins VLED1 and VLED2 are all on, the selection pins G_OUT and B_OUT are turned off, so that the light emitting diodes LED_G1, LED_G2, LED_B1, and LED_B2 do not generate light.

In the G field, the select pin G_OUT is turned on with the voltage applying pins VLED1 and VLED2 held on. Then, only the light emitting diodes LED_G1 and LED_G2 are turned on by applying the voltage Vf, so that only the G light is output. That is, even when the voltage applying pins VLED1 and VLED2 are all on, the selection pins R_OUT and B_OUT are turned off, so that the light emitting diodes LED_R1, LED_R2, LED_B1, and LED_B2 do not generate light.

In the B field, the selection pin B_OUT is turned on with the voltage applying pins VLED1 and VLED2 held on. Then, only the light of the light emitting diodes LED_B1 and LED_B2 is turned on by being applied with the voltage Vf. That is, even though the voltage applying pins VLED1 and VLED2 are all on, the selection pins R_OUT and G_OUT are turned off, so that the light emitting diodes LED_R1, LED_R2, LED_G1, and LED_G2 do not apply the voltage Vf to generate light. Don't let that happen.

As such, by connecting the light source controller and each light emitting diode as in the embodiment of the present invention, it can be seen that the number of pins is reduced by seven. The number of pins is further reduced than that of the conventional half, so that the light source controller and the light emitting diode can be connected more simply, and the area of the light source controller can be further reduced due to the reduced number of pins.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, according to the present invention, the number of fins is further increased by connecting each light emitting diode included in the same chip to a common pin, emitting light of the same color, and connecting a light emitting diode included in another chip to a common pin. Can be reduced. As the number of pins is reduced, the area of the light source controller can be further reduced.

1 is a view showing a pixel of a conventional TFT-LCD.

2 is a waveform diagram illustrating a driving method of a conventional analog liquid crystal display device.

3 is a diagram illustrating a conventional light emitting diode for emitting R, G, and B light, and a fin structure for sequentially applying the same.

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

5 is a diagram illustrating a connection relationship between a light source controller and a light emitting diode according to an exemplary embodiment of the present invention.

6 is a diagram illustrating a signal output to each pin of the light source controller in the connection relationship as shown in FIG. 5.

Claims (8)

Liquid crystal including a liquid crystal formed between the first substrate on which the first electrode is disposed and the second substrate on which the second electrode is disposed, and a light source controller for sequentially transmitting red, green, and blue light to one pixel. In a display device, First, second, and third light emitters having a first terminal commonly connected to the first terminal of the light source controller to emit different colors; A first terminal is connected to a second terminal of the light source controller, respectively, and a fourth light emitter emitting the same color as the first light emitter, a fifth light emitter emitting the same color as the second light emitter, and the same as the third light emitter. A sixth light emitter emitting color; Second terminals of the first and fourth light emitters are commonly connected to a third terminal of the light source controller, second terminals of the second and fifth light emitters are commonly connected to a fourth terminal of the light source controller, And a third terminal of the third and sixth light emitters is commonly connected to a fifth terminal of the light source controller. The method of claim 1, And the first, second, and third light emitters are formed in a first chip, and the fourth, fifth, and sixth light emitters are formed in a second chip. The method according to claim 1 or 2, The first terminal and the second terminal of the light source controller are terminals outputting a voltage for turning on the first to sixth light emitters, and the third terminal to the fifth terminal of the light source controller are the same as the first to sixth light emitters. It is a terminal which selects the light emitter which emits a color, The liquid crystal display device characterized by the above-mentioned. The method according to claim 1 or 2, And the first to sixth light emitters are light emitting diodes, and the first and second terminals of the first to sixth light emitters are anodes and cathodes, respectively. The method according to claim 1 or 2, The first terminal and the second terminal of the light source controller continuously output a voltage for turning on the first to sixth light emitters during a period in which the first to sixth light emitters emit light, and the third terminal of the light source controller A section in which the first and fourth light emitters emit light, a fourth terminal of the light source controller in a section in which the second and fifth light emitters emit light, and a fifth terminal in the light source controller in which the third and six light emitters emit light The liquid crystal display device is turned on only in the section. In the method of driving the liquid crystal display device according to claim 1, (a) turning on first to third terminals of the light source controller to emit light of the first and fourth light emitters in a first section; (b) turning on the first terminal, the second terminal, and the fourth terminal of the light source controller to emit the second and fifth light emitters in the second section; And and (c) turning on the first terminal, the second terminal, and the fifth terminal of the light source controller to emit the third and six light emitters in the third section. The method of claim 6, And displaying a color through the sum of the first light generated in the step (a), the second light generated in the step (b), and the third light generated in the step (c). Method of driving. The method of claim 6, And wherein the first, second, and third light emitters are formed in a first chip, and the fourth, fifth, and sixth light emitters are formed in a second chip.