KR101135948B1 - Driving Method for Field Sequential Color LCD - Google Patents

Abstract

The present invention relates to a method for driving a field sequential color liquid crystal display, and more particularly, to a method for driving a field sequential color liquid crystal display for improving color distortion caused by cumulative response.

In order to improve the color distortion phenomenon according to the cumulative response characteristics, which is a disadvantage of the conventional field sequential color driving method, for this purpose, a first frame in which red (R), green (G), and blue (B) light sequentially emits light; By sequentially and repeatedly driving a second frame in which green (G), red (R), and blue (B) light emits light sequentially, variations in transmittance due to cumulative response characteristics are reduced, thereby improving color distortion.

Description

Field sequential color driving method {Driving Method for Field Sequential Color LCD}

FIG. 1 is a schematic view showing an LCD of a general field sequential color driving method. FIG.

2 is a diagram showing lamp driving of a conventional field sequential color drive type LCD.

3 is an equivalent circuit diagram of a liquid crystal display unit liquid crystal cell.

4 is a view for explaining a color distortion phenomenon according to the cumulative response characteristics when implementing yellow.

5 is a view for explaining a field sequential color driving method according to the present invention.

6A is a view for explaining a case in which yellow is expressed by the field sequential color driving method according to the present invention;

6B and 6C are diagrams for describing a case in which cyan and magenta are expressed by the field sequential color driving method according to the present invention, respectively.

<Code Description of Main Parts of Drawing>

510: first frame

520: second frame

The present invention relates to a method for driving a field sequential color liquid crystal display device, and more particularly, to a method for driving a field sequential color liquid crystal display device to improve color distortion due to cumulative response.

Liquid crystal display devices (hereinafter referred to as LCDs) are manufactured in a form in which a liquid crystal layer is formed by bonding the first and second substrates at a predetermined interval and injecting liquid crystal therebetween.

The first substrate of the LCD includes a thin film transistor (hereinafter referred to as TFT) as a switching element and a pixel electrode as an electric field generating electrode, and a color filter layer and an electric field generating unit for transmitting light only in a specific wavelength range on the second substrate. The common electrode which is an electrode is formed.

When the above-mentioned TFT is turned on, an electric field is formed between the pixel electrode and the common electrode, and the arrangement angle of the liquid crystal injected by the electric field is changed, and the amount of transmitted light is adjusted according to the arrangement angle to express the desired image. do.

On the other hand, LCDs expressing color images using the color filter have a disadvantage of low luminance because light is lost to about 33% or less while passing through the color filter. In order to solve such a decrease in light efficiency, a field sequential color driving method has been proposed.

FIG. 1 schematically shows a LCD of a general field sequential color driving method.

As shown, the field sequential color driving LCD includes a liquid crystal panel 100 and a backlight assembly 130.

The liquid crystal panel 100 includes a first substrate 110 on which the TFT (T) and the pixel electrode 111 are formed, a second substrate 120 on which the color filter layer 122 and the common electrode 121 are formed; It consists of a liquid crystal layer 140 injected between the first substrate and the second substrate (110, 120), the backlight assembly 130 is a red (131, Red), green (supplying light to the liquid crystal panel 100 132, Green), and blue (133, Blue) light sources.

The field sequential color drive type LCD sequentially displays the light sources of red 131, green 132, and blue 133 to display colors using the afterimage effect of the human eye, and uses a color filter. It has advantages such as high transmittance, high resolution, and reduced number of driver ICs.

Such a field sequential color driving type LCD divides each frame into first to third subframes and turns on the light sources of red 131, green 132, and blue 133 in each subframe.

2 is a diagram illustrating lamp driving of a conventional field sequential color driving LCD.

As described above, each frame 200, 210 is divided into three subframes, that is, red, green, and blue subframes 211, 212, and 213, and are divided into red (R), green (G), and blue (B). ) Light sources repeatedly emit light.

In the sub-frames 211, 212, and 213, three light sources emit light to supply a data voltage to the liquid crystal cell using a scan pulse during the data writing time (not shown), and the liquid crystal response time (not shown). While the data supplied to the liquid crystal cell is kept constant, the lamp is turned on by the lamp driver (not shown) during the lamp lighting time 240 to supply light to the liquid crystal cell.

Accordingly, the time for the tricolor light to emit light in each subframe 211, 212, 213 is the remaining time except for the data writing time (not shown) and the liquid crystal response time (not shown).

On the other hand, in general, the arrangement angle of the liquid crystal is controlled by an electric field formed between the pixel electrode and the common electrode to express a desired image. Since a predetermined voltage is applied to the common electrode, the arrangement angle of the liquid crystal is applied to the pixel electrode. Controlled by

3 is an equivalent circuit diagram of a liquid crystal display unit liquid crystal cell.

As shown, the unit liquid crystal cell is formed in the direction in which the gate wiring GL and the data wiring DL intersect, the gate electrode is connected to the gate wiring GL, and the source electrode is connected to the data wiring DL. And a liquid crystal capacitor Cls and a storage capacitor Cs connected in parallel between the TFT, the drain electrode of the TFT and the common voltage.

At this time, the total capacitance value (liquid crystal capacitance value, storage capacitance value, and parasitic capacitance value) in the cell is different due to the difference in the liquid crystal capacitance value between the subframes, and the potential distribution in the pixel is caused by the difference in the total capacitance value. The cumulative response characteristic that causes the difference is shown.

Since the cumulative response characteristic, that is, the difference in the potential distribution in the pixel is represented by the difference in transmittance, the field sequential color driving method causes color distortion when additionally mixing light incident from the tricolor light source.

Hereinafter, a yellow color, in which humans perceive the color distortion phenomenon (color difference) most sensitively, will be described in detail as an example.

4 is a view for explaining a color distortion phenomenon according to the cumulative response characteristics when implementing yellow.

In the drawing, the curve graph indicated by the solid line shows the difference in transmittance according to the cumulative response characteristic. As shown in the drawing, the field sequential color driving method expresses yellow by additionally mixing red (R) and green (G).

At this time, when the transmittance per subframe 411, 412, 413 is about 70%, the subframe transmittance at the second cumulative response is 91%, and the subframe transmittance at the third cumulative response is 97.3%.

Therefore, arithmetic calculation of the transmittance of each subframe to implement yellow, yellow = red (70%) + green (91%) + blue (0) + red (70%) + green (91%) + blue (0 )to be. That is, since the ratio of red (R) and green (G) is 1: 1.3, and the difference is 30%, yellow close to green (G) is expressed.

As described above, the conventional field sequential color driving method repeatedly drives the light sources of red (R), green (G), and blue (B) sequentially, and in this case, color distortion due to cumulative response characteristics is disadvantageous.

Accordingly, an object of the present invention is to improve the disadvantages of the field sequential color driving method. For this purpose, a first frame in which red (R), green (G), and blue (B) light sequentially emits light, and green (G) By sequentially and repeatedly driving a second frame in which red (R) and blue (B) light emits light sequentially, color distortion due to cumulative response characteristics is improved.

Field sequential color driving method according to the present invention for the above object comprises a first frame step of sequentially emitting the first light source, the second light source, the third light source; And a second frame step in which the first light source, the second light source, and the third light source emit light in an order not identical to that of the first frame, wherein the first and second frames are sequentially and repeatedly driven.

In this case, the second light source, the first light source, and the third light source emit light sequentially in the second frame.

The first light source is a red light source, the second light source is a green light source, and the third light source is a blue light source.

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

5 is a view for explaining a field sequential color driving method according to the present invention.

As shown, the field sequential color driving method according to the present invention includes a first frame 510 in which red (R), green (G), and blue (B) light sequentially emits light in each subframe, and Green (G), red (R), and blue (B) light may be divided into a second frame 520 which sequentially emits light in the subframe, and the first frame 510 and the second frame 520 Iteratively drives repeatedly.

At this time, according to the order in which the three color light sources emit light, each pixel is synchronized with the light emission order of the three color light sources, that is, the repetitive driving order of the first frame (red, green, blue) and the second frame (green, red, blue). The driving algorithm is changed to input image data.

In this way, the first frame 510 and the second frame 520 mutually compensate for the difference in transmittance according to the cumulative response characteristics, thereby improving color distortion due to the cumulative response characteristics.

Meanwhile, in the field sequential color driving method according to the present invention, the process of emitting tricolor light in each subframe of the first frame 510 and the second frame 520 may be performed using a scan pulse during a data writing time (not shown). The data voltage is supplied to the liquid crystal cell, the data supplied to the liquid crystal cell is kept constant during the liquid crystal response time (not shown), and the lamp is turned on by the lamp driver (not shown) during the lamp lighting time to light the liquid crystal cell. Supply.

Therefore, the time for which the tricolor light emits substantially is the time remaining except for the data writing time (not shown) and the liquid crystal response time (not shown).

Hereinafter, an effect of improving color distortion according to the field sequential color driving method according to the present invention will be described with reference to the yellow, cyan, and magenta colors of FIGS. 6A to 6C.

6A is a diagram for describing a case in which yellow is expressed by the field sequential color driving method according to the present invention.

As described above, in the field sequential color driving method, yellow is represented as an additive color mixture of red (R) and green (G), and thus, two cumulative responses of red (R) and green (G) and green (G) and red It is expressed as two cumulative responses of (R).

As described above, unlike the conventional field sequential color driving method, the field sequential color driving method according to the present invention improves the color distortion caused by the cumulative response characteristics by changing the light emission order of the tricolor light sources, and the improvement effect is the transmittance for each subframe. Arithmetic calculations are obvious.

In the case of expressing yellow color using the field sequential color driving method according to the present invention, the first frame 610 and the second frame 620, more precisely, red (R), green (B), and blue (B) light are sequentially By arithmetically calculating the transmittance of the first frame 610 to emit light and the second frame 620 to which green (G), red (R), and blue (B) light sequentially emits, yellow = red (70%). ) + Green (91%) + blue (0) + green (70%) + red (91%) + blue (0), so the transmittance of red (R) and green (G) to express yellow is 161% Same as

That is, the first frame 510 and the second frame 520 are repeatedly driven in sequence so that the transmittance ratio of the red (R) and green (G) light sources becomes 1: 1 so that yellow color is not generated due to the cumulative response characteristic. Express

6B and 6C are diagrams for describing a case in which cyan and magenta are represented by the field sequential color driving method according to the present invention, respectively.

In the case of expressing cyan in the conventional field sequential color driving method, two cumulative responses of green (G) and blue (B) are expressed in two cumulative responses, and when the transmittance is calculated arithmetically, cyan = red (0 ) + Green (70%) + blue (91%) + red (0) + green (70%) + blue (91%), so the ratio of green (G) and blue (B) is 1: 1.3, 30% The difference between is that it becomes cyan, which is close to blue.

On the other hand, as shown in FIG. 6B, in the case of expressing cyan by the field sequential color driving method according to the present invention, three cumulative responses of green (G), blue (B), and green (G) are independent of blue (B). It is expressed as one response, and when the transmittance is calculated arithmetic, Cyan = red (0) + green (70%) + blue (91%) + green (97.3%) + red (0) + blue (70) %), The transmittances of green (G) and blue (B) are 167.3% and 161%, respectively.

That is, since the green (G) and blue (B) transmittance ratios are 1.04: 1, only a 4% difference is displayed, and thus a color close to the desired cyan can be expressed.

Similarly, in the case of expressing magenta by the conventional field sequential color driving method, the transmittance ratio of red (R) and blue (B) is 1.3: 1, which is 30% difference, and thus magenta close to red (R). Is expressed.

On the other hand, in the field sequential color driving method according to the present invention, as shown in FIG. 5B, one time of independent response of blue (B) and the cumulative response of three times of red (R), blue (B), and red (R) magenta Arithmetic calculation shows magenta = red (97.3%) + green (0) + blue (70%) + green (0) + red (70%) blue (91%), so red (R) The transmittances of and blue (B) are 167.3% and 161%, respectively.

That is, since the transmittance ratio of red (R) and green (G) is 1.04: 1, only a 4% difference is displayed, and thus the desired magenta color can be expressed.

In this case, the transmittance of the red (R), which is the first subframe of the first frame, is the transmittance of the cumulative response third time (97.3%). The field sequential color driving method according to the present invention is the first frame and the second frame. This is because the driving is repeated, which causes red (R) of the first frame to emit light after red (R) and blue (B) of the second frame emit light, so that the cumulative response is the third time.

As described in the examples of yellow, cyan and magenta, the field sequential color driving method according to the present invention includes a first frame in which red (R), green (G), and blue (B) emit light sequentially, green (G), By sequentially and repeatedly driving the second frame in which red (R) and blue (B) emit light sequentially, color distortion due to the cumulative response characteristic is improved.

On the other hand, in the case of yellow, cyan, and magenta described above, the case where the transmittance ratio of each additive mixed color is 1: 1 is explained. Reduce the color distortion.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, the field sequential color driving method according to the present invention includes a first frame in which red (R), green (G), and blue (B) emit light sequentially, and green (G), red (R), and blue (B). The second frame emits light sequentially, and the first frame and the second frame are sequentially repeatedly driven to reduce the variation in transmittance according to the cumulative response characteristics, thereby improving color distortion.

Claims (3)

In the field sequential color driving method in which three light sources emit light sequentially to express a color image, A first frame step of sequentially emitting the first light source, the second light source, and the third light source; A second frame step of sequentially emitting the second light source, the first light source, and the third light source Wherein the first and second frames are sequentially and repeatedly driven, wherein the first light source is a red light source, the second light source is a green light source, and the third light source is a blue light source Color drive method. delete delete

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