KR20060076936A - Field sequential driving liquid crystal display device and method for fabricating therefor - Google Patents

Abstract

The present invention relates to a field sequential driving type liquid crystal display device and a driving method thereof, and to randomly rearrange a data signal applied to a data line and to randomly arrange a lighting sequence of a corresponding sequential backlight. Prevent the phenomenon. In addition, the present invention improves the image quality of the field sequential driving liquid crystal display by including a timing controller that randomly rearranges the data signals and controls the backlight lighting sequence sequentially so as to correspond to the signals.

Timing Controller, Random, Color Breakup

Description

Field sequential driving liquid crystal display and its driving method {FIELD SEQUENTIAL DRIVING LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR FABRICATING THEREFOR}

1 is a cross-sectional view of a general field sequential liquid crystal display device.

2 is a cross-sectional view of a field sequential driving liquid crystal display device of the present invention.

3 is a waveform diagram showing a driving waveform of the field sequential driving liquid crystal display according to the exemplary embodiment of the present invention;

4 is a block diagram illustrating a driving circuit of a field sequential driving liquid crystal display according to an exemplary embodiment of the present invention.

***** Explanation of symbols for main parts of drawing *****

200: first transparent substrate 205: TFT substrate

210: gate insulating film 220: organic film

250: pixel electrode 260: second transparent substrate

265: upper substrate 290: liquid crystal layer

300: black matrix 310: thin film transistor

330: contact hole 350: planarization film

360: common electrode 400: liquid crystal panel

410: data driver 420: gate driver                 

430: timing controller 440: backlight controller

450: sequential backlight 452: red lamp

454: green lamp 456: blue lamp

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a field sequential color (FSC) liquid crystal display, and more particularly to a field sequential driving color for randomly applying a data signal corresponding to the lighting sequence of red, green, and blue sequential backlights. A liquid crystal display device and a driving method thereof are provided.

In the liquid crystal display, a TFT substrate on which a thin film transistor (TFT), which is a switch element, is formed, and a color filter substrate on which a color filter is formed, are maintained at regular intervals, and liquid crystal is injected therebetween. It is configured to include a liquid crystal panel. However, in such a liquid crystal display device, since light is lost while passing through the color filter, there is a disadvantage that the luminance is low. In general, the transmittance of light transmitted through the color filter substrate is lower than 1/3 of the total amount of light emitted from the backlight. A liquid crystal display device having a field sequential driving method has been proposed to improve such a decrease in light efficiency.

The liquid crystal display of the field sequential driving method does not include a color filter separately, but instead has a sequential backlight that sequentially emits colors of red (R), green (G), and blue (B). The sequential backlight may be composed of a red lamp, a green lamp, and a blue lamp, and each lamp may be configured of a light emitting diode (LED). The conventional field sequential driving LCD displays time-dividing one frame into three sub-frames, and additionally mixes red, green, and blue light generated in each sub-frame to color. Implement

Hereinafter, a structure of a general field sequential driving type liquid crystal display will be described with reference to FIG. 1.

Referring to FIG. 1, a general field sequential driving type liquid crystal display device 60 includes a first substrate 70 and a second substrate 90 which are opposed to each other to have a predetermined distance from each other; A liquid crystal layer 80 formed at a distance between the first substrate 70 and the second substrate 90; Red, green, and blue light is emitted to the liquid crystal display panel 65 disposed on the rear surface of the second substrate 90 and composed of the first substrate 70, the second substrate 90, and the liquid crystal layer 80. It is composed of red (R), green (G), blue (B) backlight 100 to supply.

The lower surface of the transparent substrate 71 of the first substrate 70 is provided with a black matrix 72 for dividing the pixels and preventing leakage of light due to gaps between the pixels.

In addition, the lower surface of the transparent substrate 71 is provided with a transparent common electrode 73 for applying an electric field to the liquid crystal layer 80 together with the pixel electrode formed on the second substrate.

On the other hand, a thin film transistor (TFT) as a switching element on the transparent substrate 91 of the second substrate 90; A transparent pixel electrode 92 is provided to receive a signal from the TFT and apply an electric field to the liquid crystal layer 80 together with the common electrode 73.                         

Although not shown in detail in the drawings, a plurality of gate lines are arranged at regular intervals on the transparent substrate 91 of the second substrate 90; The pixel electrodes 92 are separately provided in the plurality of data lines perpendicular to the gate lines and arranged at regular intervals, and in unit pixels defined by the gate lines and the data lines.

The thin film transistor TFT may include a gate electrode in electrical contact with the gate lines; A source electrode in electrical contact with the data lines; A drain electrode in electrical contact with the pixel electrode 92 is provided.

The most distinctive feature of the field sequential drive type liquid crystal display device 60 is that a color filter is not required, and red (R), green (green) light which sequentially turns on red, green and blue light sources is not required. G), it is provided with the sequential backlight 100 of blue (B).

The red (R), green (G), and blue (B) backlights 100 flash red, green, and blue light sources 60 times a second for a total of 180 times by an inverter (not shown). By this, the afterimage effect of vision is generated and the colors are expressed by mixing red, green, and blue with each other.

The red, green, and blue light sources flash 180 times per second, but the actual human view recognizes that the red, green, and blue light sources are all turned on.

For example, when the red light source is turned on first, and then the blue light source is turned on, the phenomenon which appears purple due to the afterimage effect of vision is applied.                         

The above-described field sequential driving type liquid crystal display device overcomes the problem of deterioration in brightness of a general liquid crystal display device to which a color filter is applied, and implements natural colors by applying a backlight having red, green, and blue light sources. The high brightness and contrast characteristics, and the manufacturing cost are reduced, there is an effective advantage in manufacturing a large area liquid crystal display.

However, in the field sequential driving type liquid crystal display, the red, green, and blue backlights sequentially flash at regular intervals, and red, green, and blue are decomposed temporally, and the same color is repeated at regular intervals every frame. Therefore, red, green, and blue colors are decomposed to show color break-up when the naked eye moves, expresses a moving picture, or shakes the LCD. The color breakup phenomenon is a deterioration of the image quality as the biggest disadvantage of the field sequential driving type liquid crystal display device.

Therefore, an object of the present invention is to solve the color breakup problem in a field sequential liquid crystal display device and to improve image quality.

Other features and objects of the present invention will be described in detail in the configuration and claims of the invention below.

In order to achieve the above object, the present invention provides a method comprising: dividing a frame into three subframes representing red, green, and blue; Arranging data signals such that one frame includes red, green, and blue subframes, and adjacent frames are arranged in different order of the subframes; Forming a backlight control signal in the same order as the subframe arrangement order of the data signal; Transmitting the control signal to a backlight controller; According to an exemplary embodiment of the present invention, a method of driving a field of a liquid crystal display device is provided.

The present invention also includes a timing controller for dividing a frame into three subframes displaying red, green, and blue, and rearranging and outputting input image data such that subframes included in adjacent frames are arranged in different order; A backlight controller receiving a backlight control signal from the timing controller; And a sequential backlight flashing randomly by the control signal.

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

2 is a side sectional view showing a field sequential driving liquid crystal display according to an embodiment of the present invention.

As described above, the field sequential driving liquid crystal display has no color filter and includes a sequential backlight 450 including a red lamp 452, a green lamp 454, and a blue lamp 456. The lamps 452, 454, and 456 are composed of LEDs.

The lower substrate 205 and the upper substrate 265 are bonded together with the liquid crystal layer 290 filled in the cell gap d to form a liquid crystal panel. The backlight 450 is sequentially provided below the lower substrate 205.                     

In the lower substrate 205, a TFT 310 is formed on each of the pixel areas on the first transparent substrate 200 to apply and block a signal voltage to the pixel electrode.

The TFT 310 is a gate electrode 312 to which a gate signal is applied, a semiconductor layer 314 that is activated in response to the gate signal to form a channel, and n ⁺ doped to form the channel 314. Active layer 316 formed on both sides of the upper side, a gate insulating film 210 that electrically isolates the active layer 316 and the gate electrode 312, and a data signal formed on the active layer 316. A source electrode 318 that is input and a drain electrode 320 that applies a data signal input to the source electrode 318 to the pixel electrode 250 as the semiconductor layer 314 is activated.

The organic layer 220 is formed on the TFT 310 to protect the source electrode 318 and the drain electrode 320 and to provide a high opening ratio. The organic layer 220 on the drain electrode 320 is etched to form a contact hole 330, and the drain electrode 320 and the pixel electrode 250 are electrically connected to each other through the contact hole 330. Connected.

A black matrix 300 is formed on the upper substrate 265 at the boundary of each pixel of the second transparent substrate 260. As described above, the field sequential driving liquid crystal display has no color filter. The planarization film 350 is formed on the surface of the upper substrate 265 for a gentle step. In addition, indium tin oxide (ITO) is deposited on the surface of the planarization film 350 using the common electrode 360 to apply a voltage to the liquid crystal layer 290 together with the pixel electrode 250 of the TFT substrate 310.                     

The sequential backlight 450 generates red (R), green (G), and blue (B) light for one frame, but there is a sequence of red, green, and blue subframes between the frame and the adjacent frame. It is controlled to be different and serves to irradiate light into the liquid crystal panel.

Conventional sequential backlights emit red (R), green (G), and blue (B) lights in a certain order, while the present invention randomly flashes the sequential backlight for a period of time, for example, 60 seconds for 1 second. do. That is, the conventional field sequential driving liquid crystal display has a sequential backlight that blinks in a regular order, so that a color breakup phenomenon in which color is broken due to blinking eyes or shaking of the liquid crystal display panel occurs. Therefore, the present invention prevents color breakup by inducing color blending through random time division by randomly configuring the blinking sequence of the backlight.

The sequential backlight also consists of a red lamp 452, a green lamp 454, and a blue lamp 456. Unlike the backlight that irradiates the conventional white light, the sequential backlight 450 of the field sequential driving method does not need a color filter because it displays a color in itself. Since there is no color filter, transmittance is increased, thereby improving brightness.

Hereinafter, an operation of randomly applying a data voltage and a sequential backlight control signal will be described with reference to FIG. 3.

3 is a waveform diagram showing driving waveforms of the field sequential driving liquid crystal display according to the exemplary embodiment of the present invention.                     

The field sequential driving liquid crystal display divides one frame into three subframes as shown in the figure. Each subframe is displayed for 5.56 ms as described above, during which a gate pulse GP is generated by the gate driver by a gate start pulse supplied from the timing controller.

The subframe is divided into a scan section ST, a response section RT, and a lamp lighting section FT.

The scan period ST is a period in which the gate pulse GP is applied to the TFT, and a data voltage is applied to the pixel electrode in response to the gate pulse GP.

The reaction section RT is a section in which the liquid crystal responds to the applied data voltage, and the applied data voltage is kept constant. When voltage is applied to the liquid crystal, the liquid crystal moves in the direction of the long axis in the direction of the electric field in proportion to the magnitude of the voltage. The time required for this is the reaction section (RT). After passing through the reaction section (RT), the liquid crystal can transmit light at a desired transmittance.

During the lighting period FT, the transmittance of the liquid crystal is kept constant. At this time, the lamp is turned on so that light passes through the liquid crystal to display a desired color.

In detail, in the field sequential driving liquid crystal display according to the exemplary embodiment of the present invention, when the R data voltage is supplied to the liquid crystal cell in response to the gate pulse GP during the scan period ST in the first subframe of one frame, Responds to the R data voltage. Then, the liquid crystal passes through the reaction section RT to reach the desired transmittance of the liquid crystal. At this time, the red lamp R is turned on during the lighting section FT to transmit red light to the liquid crystal cell. Accordingly, red light is displayed at a desired transmittance in the liquid crystal cell to which the R data voltage is supplied in the first subframe of the first frame.

In the same manner, the second subframe and the third subframe are driven to display the green light and the blue light at a desired transmittance, and to realize colors by the combination of the three colors.

By the way, the sequential backlight of the conventional field sequential driving liquid crystal display device is comprised so that the lighting sequence of red, green, and blue may appear repeatedly. That is, red, green, and blue are repeated with a certain rule.

However, in the field sequential driving liquid crystal display of the present invention, as shown in FIG. 3, each frame is composed of red, green, and blue subframe sections, but the subframes of each frame are configured differently. Therefore, as a whole, the arrangement order of subframes is random. By doing so, a particular color may be highlighted to prevent color breakup when the screen is broken when parallax occurs. In other words, since the order of subframes is conventional, the 3Nth subframe in the first subframe shows the same color. Therefore, if the user blinks, looking at the first subframe before blinking and then looking at the third Nth subframe after blinking, the specific color is highlighted.

However, according to the present invention, since the probability that the first subframe and the 3Nth subframe are the same is 1/3, the likelihood of a particular color being highlighted is reduced.

Although the arrangement order of the subframes is random, it is preferable that the third subframe of the first frame and the first subframe of the second frame adjacent thereto are arranged to have different colors. That is, as shown in FIG. 3, when the third subframe of the first frame is blue, the first subframe of the second frame may be arranged in red or green. This is because when the same colors are arranged consecutively, arbitrary colors may be emphasized in the image quality, which may negatively affect the color implementation.

In addition, the sequence of the subframes is not randomly arranged indefinitely, and it is sufficient to randomly arrange only for a predetermined time interval for convenience of driving.

That is, the arrangement order of the subframes may be performed in the process of rearranging the data voltage signals in the timing controller. The order of subframes is randomly arranged for a predetermined time interval, that is, for 1 second 60 frames, and then for 1 second. May use the same subframe array order as in the previous subframe array order.

In other words, when repeating one frame consisting of R, G, and B for 60 seconds for one second, 180 subframes can be randomly arranged as in RGBGBRBRGRBGRGB ..... Then, the next one second is the same as the subframe arrangement order again, which is sufficient to prevent the color breakup phenomenon. This simplifies the operation of the timing controller, which must arrange data signals randomly.

Hereinafter, a block diagram of a driving circuit according to an embodiment of the present invention will be described with reference to FIG. 4.

The liquid crystal display device according to the present invention includes a liquid crystal panel 300 having a plurality of data wires and a gate wire intersecting and a TFT formed at an intersection thereof, a data driver 310 for supplying data to the data wires of the liquid crystal panel 300; And a gate driver 320 for supplying the gate pulse GP to the gate wiring of the liquid crystal panel 300, and a timing for supplying a randomly rearranged image data and a control signal for sequentially determining the lighting order of the backlight. A timing controller 330 and a backlight controller 340 for driving the sequential backlight 450 including the red lamp 452, the green lamp 454, and the blue lamp 456 are provided.

The TFT formed at the intersection of the data line and the gate line of the liquid crystal panel 300 supplies the data voltage to the liquid crystal cell in response to the gate pulse GP from the gate driver 320. The source electrode of the TFT is connected to the data wiring, and the drain electrode is connected to the pixel electrode of the liquid crystal cell. The gate electrode of the TFT is connected to the gate wiring.

The timing controller 330 divides one frame into three subframes of red (R), green (G), and blue (B), and provides a data driver 310 and a liquid crystal panel control signal for driving the liquid crystal panel 300. The gate driver 320 is supplied. When the liquid crystal display is driven at 60 Hz, one frame is displayed for 16.7 ms and each sub frame is displayed for 5.56 ms, one third thereof.

To this end, the timing controller 330 rearranges image data supplied from a graphic controller (not shown) such as a computer for each of red (R), green (G), and blue (B). The image data rearranged by the timing controller 330 is supplied to the data driver 310. In addition, the timing controller 330 generates a data control signal and a gate control signal at frequencies necessary for the field sequential driving method. The data control signal is supplied to the data driver 310 including a source shift clock SSC, a source output enable SOE, a polarity inversion signal POL, and the like. The gate control signal is supplied to the gate driver 420 including a gate start pulse GSP, a gate shift clock GSC, a gate output enable GOE, and the like.

The timing controller 330 arranges the image data in red, green, and blue colors so that the arrangement order is random.

On the other hand, the timing controller 330 is randomly arranged so that the red lamp 452, the green lamp 454 and the blue lamp 456 match the alignment order of the image data when the data is completely supplied to the liquid crystal cell The backlight control signal is generated to control the backlight controller 340.

After sampling the data according to the data control signal from the timing controller 330, the data driver 310 latches the sampled data line by line and converts the latched data into a gamma voltage. do.

The gate driver 320 includes a shift register that sequentially generates the gate pulse GP in response to the gate start pulse GSP among the gate control signals from the timing controller 330, and a voltage of the gate pulse GP. And a level shifter for shifting the voltage to a voltage level suitable for driving the liquid crystal cell. The timing controller 330 supplies the gate start pulse GSP to the gate driver 320 as a control signal. The gate driver 320 generates a gate pulse GP in response to the gate start pulse GSP.

When the image data is arranged as described above, any frame has red, blue, and green subframes, but the entire frame is arranged in random order, and accordingly, the driving sequence of the backlight is also randomized. Color breakup of the device can be improved.

Claims (8)

A dividing step of dividing one frame into three subframes representing red, green, and blue; Arranging data signals such that red, green, and blue subframes are included in one frame, and the arrangement order of the subframes is different between adjacent frames; Forming a backlight control signal in the same order as the subframe arrangement order of the data signal; Transmitting the control signal to a backlight controller; And driving a backlight according to the control signal. 2. The method of claim 1, wherein the red, green, and blue sub-backlights blink randomly according to the control signal. 2. The method of claim 1, further comprising: transmitting the data signal to a data line; Driving a liquid crystal by the data signal; And driving a backlight according to the backlight control signal. The method of claim 1, wherein aligning the data signal Including a red, green and blue subframe in one frame, the sub-frame included in the adjacent frame includes the step of arranging N frames so that the arrangement order is different from each other, the field sequential driving of the liquid crystal display device Way. 5. The method of claim 4, wherein the N frames are 60 frames corresponding to 1 second. A timing controller for dividing one frame into three subframes displaying red, green, and blue, and rearranging and outputting input image data such that the arrangement order of subframes included in adjacent frames is different; A backlight controller receiving a backlight control signal from the timing controller; And And a sequential backlight flashing randomly by the control signal. 7. The field sequential driving liquid crystal display device according to claim 6, wherein the arrangement order of sub-frames included in the image data is random. 8. The field sequential driving liquid crystal display according to claim 7, wherein the control signal causes the lighting sequence of the sequential backlight to be the same as the subframe arrangement order of the image data.

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