KR100684784B1 - FS-LCD and Driving method threrof - Google Patents

Abstract

The present invention includes a plurality of scan lines, a plurality of data lines insulated from and intersecting the scan lines, and a plurality of pixels formed in an area surrounded by the scan lines and the data lines, wherein one pixel among the plurality of pixels is red, A liquid crystal display device and a driving method thereof, which sequentially transmit green and blue color light, and each of the red, green, and blue fields, transmits the color light and detects the color light in a predetermined region of a period in which the color light is transmitted. Compare the detected color light with a reference value, and then, if the detected color light is less than the reference value, increase the current value driving the detected color light, and if the detected color light is greater than the reference value, the detected color light The color coordinates are controlled by decreasing the current value driving. By doing in this way, the reference color coordinate value set initially can be kept constant.

LCD, Drive, Color Coordinate, FS

Description

Liquid crystal display and its driving method {FS-LCD and Driving method threrof}

1 is a view showing a liquid crystal display device according to an embodiment of the present invention.

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

3 is a flowchart illustrating an operation of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a view illustrating an enable time of a light source and a sensor of the liquid crystal display according to the exemplary embodiment of the present invention.

5 is a diagram illustrating a relationship between a driving current and a voltage for driving a light source.

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.

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.

On the other hand, in a general liquid crystal display device, a sensor is installed in each of red, green, and blue cells so as to have a white balance value designated by a user, and at the same time, the output of the sensor is sensed and the current or voltage is adjusted according to the result value. The color coordinate value was controlled by adjusting.

However, such a conventional method has a problem that it is difficult to detect an accurate color coordinate in the field sequential driving method due to the characteristics of the driving method.

The technical problem to be achieved by the present invention is to solve the disadvantages of the prior art, the sensor for detecting each color light in the pixels representing the colors of each of the red, green, and blue, and the color coordinates accurately at the emission time of each color light The present invention provides a liquid crystal display and a driving method thereof.

According to one aspect of the present invention for achieving the above object, a liquid crystal display device,

A plurality of scan lines for transmitting a scan signal, a plurality of data lines insulated from and intersecting the scan lines, a switching element formed in an area surrounded by the scan lines and data lines, and connected to the scan lines and data lines, respectively; A liquid crystal display panel including a plurality of pixels arranged in a matrix form;

A scan driver for sequentially supplying scan signals to the scan lines;

A gray voltage generator which generates a gray voltage corresponding to the gray;

A data driver for supplying a gray voltage output from the gray voltage generator to a corresponding data line; And

A light source sequentially outputting first, second, and third color lights to one pixel;

Controlling first, second, and third color light output from the light source sequentially for each of a first field, a second field, and a third field, for each first time; A color coordinate control unit controlling to sense the color light for a second time when the output time is less than the first time;

First, second, and third sensors for sensing and outputting first, second, and third color lights respectively applied to the pixel according to a control signal of the color coordinate controller;

An analog / digital converter for converting and outputting color light sequentially output from the first, second and third sensors into a digital signal;

A color coordinate checker which measures and outputs each color coordinate from first, second and third color lights sequentially output from the analog / digital converter according to a control signal of the color coordinate controller;

A memory for storing reference color coordinate values for the first, second, and third color lights;

And a light source controller for comparing the color coordinate values output from the color coordinate checker with the reference color coordinate values stored in the memory and controlling the current supplied to the light source so as to reduce the difference.

A driving method of a liquid crystal display device according to an aspect of the present invention for achieving the above object,
A plurality of scan lines and a plurality of data lines insulated from and intersecting the scan lines, a plurality of data lines arranged in a matrix form having a switching element connected to the scan lines and the data lines, respectively; A driving method of a liquid crystal display device comprising a pixel, and including a light source sequentially transmitting first, second and third color light to one of the plurality of pixels.
The driving method includes a first field, a second field, and a third field for driving the first, second, and third light, respectively,
For each of the first field, second field and third field,
Transmitting a color light corresponding to each field from the light source;
Detecting a color light transmitted from the light source in a predetermined period of time during which the color light is transmitted, and comparing the detected color light with a reference color coordinate; And

As a result of the comparison in the second step, if the color coordinate value of the detected color light is smaller than the reference color coordinate value, the current value of the light source driving the detected color light is increased, and the color coordinate value of the detected color light is the reference color coordinate value. If greater, a third step of reducing the current value of the light source for driving the sensed color light.

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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.

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

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention may be used.

The liquid crystal display panel 100, the scan driver 200, the data driver 300, the gray voltage generator 400, the timing controller 500, the common voltage generator 600, and the R, G, and B light sources are respectively Output light emitting diodes 700a, 700b, 700c, light source controller 800, color coordinate control unit 900, color coordinate checker 1000, analog / digital converter 1100, sensors 1200a, 1200b, 1200c, and memory 1300 ).

A plurality of scan lines Sn are formed in the liquid crystal display panel 100 to transmit a gate-on signal, and are insulated from and intersect with the plurality of scan lines to transfer gray data voltages and reset voltages corresponding to gray data. The data line Dm is formed. A plurality of pixels arranged in a matrix form is surrounded by a scan line and a data line, and each pixel is connected to the thin film transistor 10 and the drain electrode of the thin film transistor, in which a gate electrode and a source electrode are connected to the scan line and the data line, respectively. Are connected, and the other side includes a pixel capacitor C1 and a storage capacitor Cst connected to the common electrode line.

The scan driver 200 sequentially applies a scan signal to the scan line to turn on the pixel to which the scan signal is applied. The timing controller 500 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) is supplied to the scan driver 200, the data driver 300, and the color coordinate control unit 900, respectively, and the gray scale data R, G, and B DATA are supplied to the gray voltage generator 400. The gray voltage generator 400 generates a gray voltage having a magnitude corresponding to gray data and supplies it to the data driver 300. The common voltage generator 600 generates a common voltage Vcom and supplies the same to the TFT. The color coordinate controller 900 controls to sequentially output the red, green, and blue color light output from the light source for each of the red field, the green field, and the blue field for each first time, and output the red, green, and blue color light. And control the color light for a second time that is less than or equal to the first time. The sensors 1200a, 1200b, and 1200c detect and output red, green, and blue color light applied to the pixel for a second time according to a control signal of the color coordinate controller 900. The analog / digital converter 1100 converts color light sequentially output from the sensors 1200a, 1200b, and 1200c into a digital signal and outputs the digital signal. The color coordinate inspector 1000 measures and outputs each color coordinate from red, green, and blue color light sequentially output from the analog / digital converter 1100 according to the control signal of the color coordinate control unit 900. The memory 1300 stores reference color coordinate values for red, green, and blue color lights. The light emitting diodes 700a, 700b, and 700c respectively output light corresponding to R, G, and B to the LCD panel, and the light source controller 800 controls when the light emitting diodes 700a, 700b, and 700c are turned on. The color coordinate value output from the color coordinate checker 1000 is compared with the reference color coordinate value stored in the memory 1300 to control the current supplied to the light source to reduce the difference. In this case, according to an exemplary embodiment of the present invention, the timing controller 500 may be configured to supply the grayscale data from the data driver 300 to the data line and to turn on the R, G, and B light emitting diodes by the light source controller 800. It can be synchronized by the control signal provided by.

Next, the operation of the liquid crystal display according to the embodiment of the present invention having such a configuration will be described in detail.

3 is a flowchart illustrating an operation of a liquid crystal display according to an exemplary embodiment of the present invention.

Initially, color coordinate values are stored in the memory 1300 according to a user's setting or a maker's setting, and the light sources 700a, 700b, and 700c are driven with a current corresponding to the set color coordinate values.

Thereafter, when the user applies power to the liquid crystal display, the timing controller 500 controls the gray level data signals R, G, and B data, the horizontal synchronization signal Hsync, and the vertical synchronization signal from an external or graphic controller (not shown). Receives the signal Vsync and supplies necessary control signals Sg and Sd to the scan driver 200 and the data driver 300, the color coordinate control unit 900, respectively, and the gray scale data R, G, and B DATA. Supply to generator 400.

Then, the scan driver 200 sequentially applies the scan signal to the scan line, turns on the pixel to which the scan signal is applied, and the gray voltage generator 400 generates a gray voltage having a magnitude corresponding to the gray data. The common voltage generator 600 generates a common voltage Vcom and supplies the TFT 300 to the driver 300.

The light emitting diodes 700a, 700b, and 700c output light corresponding to R, G, and B to the LCD panel, and the light source controller 800 controls the lighting timing of the light emitting diodes 700a, 700b, and 700c. 4, light corresponding to R of the light emitting diode 700a is output to the red field, light corresponding to G of the light emitting diode 700b is output to the green field, and light emitting diode to the blue field. Control to output light corresponding to B of 700c.

By this process, data is displayed on the liquid crystal display panel 100.

Meanwhile, the color coordinate control unit 900 sequentially outputs the red, green, and blue color light output from the light sources 700a, 700, and 700c for each of the red field, the green field, and the blue field, for each time corresponding to one field. The control signal is output to the sensors 1200a, 1200b, and 1200c to detect the color light for a time smaller than the time of the one field (RS, GS, BS).

Then, the sensors 1200a, 1200b, and 1200c detect and output red, green, and blue color lights applied to the pixels for the time RS, GS, and BS, respectively, according to the control signal of the color coordinate controller 900. The analog-to-digital converter 1100 converts color light sequentially output from the sensors 1200a, 1200b, and 1200c into a digital signal and outputs the digital signal.

The color coordinate inspector 1000 measures and outputs each color coordinate from red, green, and blue color light sequentially output from the analog / digital converter 1100 according to the control signal of the color coordinate control unit 900.

Then, the light source controller 800 receives the red (R) color coordinate value from the color coordinate inspector 1000 (S201) and compares the reference color coordinate values for red stored in the memory 1300 (S202).

As a result of the comparison, if the input red color coordinate value is smaller than the reference value, the driving current supplied to the light source 700a is increased in proportion to the absolute value of the difference (S203), and if the input red color coordinate value is larger than the reference value, the light source 700a In step S204, the driving current to be supplied is reduced in proportion to the absolute value of the difference.

Then, the light source controller 800 receives the green color coordinate value from the color coordinate inspector 1000 (S205) and compares the reference color coordinate values for the green stored in the memory 1300 (S206).

As a result of the comparison, if the received green color coordinate value is smaller than the reference value, the driving current supplied to the light source 700b is increased in proportion to the absolute value of the difference (S207). If the input green color coordinate value is larger than the reference value, the light source 700b In step S208, the driving current to be supplied is reduced in proportion to the absolute value of the difference.

Then, the light source controller 800 receives the blue color coordinate value from the color coordinate checker 1000 (S209) and compares the reference color coordinate values for blue stored in the memory 1300 (S210).

As a result of the comparison, if the received blue color coordinate value is smaller than the reference value, the driving current supplied to the light source 700c is increased in proportion to the absolute value of the difference (S211). If the received blue color coordinate value is larger than the reference value, the light source 700c In step S212, the driving current to be supplied is reduced in proportion to the absolute value of the difference.

Of course, if the reference value and the input red, green or blue color coordinate values match, the adjustment is not made separately, and the above process is repeated so that the color coordinates always maintain the initially set reference value.

Here, although the light source is controlled by controlling the driving current, it can be controlled by voltage as necessary. In this case, since the relationship between the voltage and the current driving the light source is in proportional relationship as shown in FIG. The voltage value can be determined using the graph.

According to this embodiment of the present invention, by detecting the respective color light at the time corresponding to the time to apply the color light in each of the red, green and blue fields, it is possible to accurately determine the color coordinates and adjust it.

In this embodiment of the present invention, the time for detecting the color light is less than one field period, but this may be modified as necessary, and may be modified in a condition that is most suitable for detecting the color light.

Although the above has been described with reference to embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

 As described above, according to the present invention, even if the initial color coordinate value changes over time, the correct color can be displayed by maintaining the original color coordinate value through correction.

Claims (5)

A matrix comprising a plurality of scan lines for transmitting a scan signal, a plurality of data lines insulated from and intersecting the scan lines, a switching element formed in an area surrounded by the scan lines and data lines, and connected to the scan lines and the data lines, respectively; A liquid crystal display panel including a plurality of pixels arranged in a form; A scan driver for sequentially supplying scan signals to the scan lines; A gray voltage generator which generates a gray voltage corresponding to the gray; A data driver for supplying a gray voltage output from the gray voltage generator to a corresponding data line; And A light source sequentially outputting first, second, and third color lights to one pixel; Controlling first, second, and third color light output from the light source sequentially for each of a first field, a second field, and a third field, for each first time; A color coordinate control unit controlling to sense the color light for a second time when the output time is less than the first time; First, second, and third sensors for sensing and outputting first, second, and third color light beams applied to the pixel from the light source for a second time according to a control signal of the color coordinate controller; An analog / digital converter for converting and outputting color light sequentially output from the first, second and third sensors into a digital signal; A color coordinate checker which measures and outputs each color coordinate from first, second and third color lights sequentially output from the analog / digital converter according to a control signal of the color coordinate controller; A memory for storing reference color coordinate values for the first, second, and third color lights; And And a light source controller for comparing the color coordinate values output from the color coordinate checker with the reference color coordinate values stored in the memory and controlling a current supplied to the light source so that the difference is reduced. The method of claim 1, If the input color coordinate value is smaller than the reference color coordinate value, the light source controller increases the driving current supplied to the light source in proportion to the absolute value of the difference, and if the input color coordinate value is larger than the reference color coordinate value, the light source controller supplies the light source to the light source. And reducing the driving current in proportion to the absolute value of the difference. The method according to claim 1 or 2, And the first, second, and third color lights are red and green blue light. A plurality of scan lines, a plurality of data lines insulated from and intersecting the scan lines, a plurality of data lines arranged in a matrix form having a switching element connected to the scan lines and the data lines, respectively; A driving method of a liquid crystal display device comprising a pixel, and including a light source sequentially transmitting first, second and third color light to one of the plurality of pixels. The driving method includes a first field, a second field, and a third field for driving the first, second, and third light, respectively, For each of the first field, second field and third field, Transmitting a color light corresponding to each field from the light source; Detecting a color light transmitted from the light source in a predetermined period of time during which the color light is transmitted, and comparing the detected color light with a reference color coordinate; And As a result of the comparison in the second step, if the color coordinate value of the detected color light is smaller than the reference color coordinate value, the current value of the light source driving the detected color light is increased, and the color coordinate value of the detected color light is the reference color coordinate value. If greater than, the driving method of the liquid crystal display device comprising a third step of reducing the current value of the light source for driving the sensed color light. The method of claim 4, wherein And the first, second and third color lights are red, green and blue light.

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