CN101807381B - Drive method for dynamically driving field order color liquid crystal display - Google Patents

Abstract

The invention discloses a drive method for dynamically driving a field order color liquid crystal display. In a dynamically-driven field order color liquid crystal display with a passive matrix, which is dynamically driven by means of line by line scanning method, a backlight source at least has two or more different colors, and the line scanning method of the dynamically-driven field order color liquid crystal display with the passive matrix comprises the steps of: applying drive voltage of each COM in the same field according to a certain sequence; at least reversely rotating the polarity of the voltage once; and adding non-scanning time in each field except for the scanning time of COM. The drive method has the advantage that the display colors of all COM in the same field are substantially consistent if the drive waveforms are same.

Description

Driving Method for Dynamically Driving Field Sequential Color Liquid Crystal Display

technical field

The invention relates to a driving method for a passive matrix dynamic driving field sequence color liquid crystal display.

Background technique

Field-sequential color liquid crystal display usually divides a color picture (frame) into three pictures (fields) of red (R), green (G) and blue (B) sequentially in time, and then switches those pictures sequentially at high speed (fields) constitute a color picture (frame). If the three primary colors of R, G, and B are used, the display time of each site is 1/3 of the display time of a frame, that is, three fields constitute a frame period. If 2-color or 4-color, the display time of each field is 1/2 or 1/4 of the display time of a frame period, that is, 2 fields or 4 fields constitute a frame period, and the rest of the cases are analogized. The existing dynamically driven field sequential color liquid crystal display, its general structure includes a liquid crystal display, a backlight, a backlight driver and a liquid crystal driver, the backlight is arranged on the bottom side of the liquid crystal display, the backlight driver and the liquid crystal The display driver drives the backlight and LCD respectively. This driving method for dynamically driving a field sequential color liquid crystal display is shown in Figure 5 (Figure 5 shows an example of positive display mode (the liquid crystal screen is transmissive when the voltage is OFF) 1/2 duty ratio driving, obviously, other duty ratios Duty ratio drive also has the same problem below), as shown in the figure, when we input the same red drive waveform from COM1 and COM2 respectively, that is to make the pixel turn on in the red light area and turn off in the blue light area. In order to eliminate the DC component, the polarity of the driving waveform in the same field is reversed at least once. Since the liquid crystal material has a delayed response time to the driving voltage, when the pixel is turned on and off, its light transmission intensity has a rising and falling region. Because the time periods of COM1 and COM2 are different, the rising region of COM1 is in the cyan region. The rising area of COM2 is in the red area. Although the red of COM1 has cyan components, its red transmission intensity is greater than that of COM2, and the light leakage component of cyan is smaller than that of COM2. This causes the red color of COM1 to be different from that of COM2 in the same screen. Of course, the same happens when other colors are displayed. If we use the negative display mode (the LCD screen is projected when the voltage is ON), as shown in Figure 6, when we input the same red driving waveform from COM1 and COM2 respectively, the red falling area of COM2 is in the subsequent cyan area. And COM1 has no cyan light leakage. The red color of COM1 and COM2 is different. If other duty cycles are used to drive this type of display, such as 1/3, 1/4...1/N, the same problem exists.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects, and provide a driving method for passive matrix dynamic driving field sequential color liquid crystal display in which the display colors of all COMs in the same field are basically the same if the driving waveforms are the same.

A driving method for dynamically driving a field sequential color liquid crystal display is provided, in a passive matrix dynamic driving field sequential color liquid crystal display which is dynamically driven by a progressive scanning method and whose backlight source includes at least two or more different colors , the row scanning method of the passive matrix dynamic driving field sequence color liquid crystal display is that each COM in the same field is applied with a driving voltage in a certain order, and the polarity of the driving voltage is reversed at least once. In addition to the scanning time of COM in the field, non-scanning time is also added.

The passive matrix is relative to the active matrix. The so-called active matrix means that switching elements are added to each pixel, and the switching elements usually use TFT components. The driving method of the active matrix and the response characteristics of the liquid crystal are completely different from those of the passive matrix.

The non-scan time is placed before or after the scan time.

The sum of scanning time and non-scanning time of COM in each field is greater than or equal to the lighting time of the backlight source in the same field.

Regardless of whether the passive matrix dynamic drive field sequential color liquid crystal display is in positive display mode or negative display mode, all voltages between COM and SEG are OFF or zero during non-scanning time.

The passive matrix dynamically driven field sequential color liquid crystal display is a dynamically driven field sequential color liquid crystal display with a frame rate between 45 Hz and 200 Hz.

The passive matrix dynamic drive field sequential color liquid crystal display is TN, STN, HTN, OCB, VA type non-bistable dynamic drive field sequential color liquid crystal display.

When the colors of the backlight are two colors, the two colors are complementary colors; or, the colors of the backlight are red, green and blue.

The passive matrix dynamic drive field sequential color liquid crystal display includes a liquid crystal display, a backlight source, a backlight driver and a liquid crystal display driver, the backlight is arranged on the bottom side of the liquid crystal display, the backlight driver and the liquid crystal display The display driver drives the backlight and LCD respectively.

The reciprocal of the duty cycle of the driving waveform of the passive matrix dynamic driving field sequential color liquid crystal display is equal to the actual number of COMs of the display.

The reciprocal of the duty cycle of the driving waveform of the passive matrix dynamic driving field sequence color liquid crystal display is greater than the actual number of COMs of the display.

Each COM can be scanned multiple times in the same field, and the non-scanning time can be set multiple times.

It should be noted that generally in dynamic driving it is necessary to perform waveform inversion in the same field, at this time there are two waveforms (A and B) that can be used. A is COM1(+)COM1(-)COM2(+)COM2(-), B is COM1(+)COM2(+)COM1(-)COM2(-). We only use A as an example in this description. Of course B is also applicable.

In the present invention, due to the adoption of each COM in the same field to be scanned, in addition to the scanning time of COM in each field, the non-scanning time is also increased, so that it can effectively prevent the last drive waveform from The rising area (positive display) or falling area (negative display) of the transmission intensity extends into other adjacent color areas, which greatly improves the display color consistency of this type of display.

Description of drawings

FIG. 1 is a schematic diagram of the driving waveform principle of positive display driven by 1/2 duty ratio of the present invention.

Fig. 2 is a schematic diagram of the driving waveform principle of the negative display driven by the 1/2 duty ratio of the present invention.

FIG. 3 is a schematic diagram of the principle of positive display driving waveforms for driving a display with a duty ratio of 1/3 with a driving wave of 1/4 duty ratio.

FIG. 4 is a schematic diagram of the principle of negative display driving waveforms for driving a display with a duty ratio of 1/3 with a driving wave of 1/4 duty ratio.

Fig. 5 is a schematic diagram of a positive display driving waveform of an existing dynamic driving field sequential color liquid crystal display.

Fig. 6 is a schematic diagram of negative display driving waveforms of a conventional dynamic driving field sequential color liquid crystal display.

Detailed ways

For the convenience of narration, the present invention is illustrated by taking the backlight as an example of two different color displays, but it should be noted that the present invention is also suitable for displays with more than two different colors, such as three different colors ( Typical are displays of red, green and blue), four different colors or five different colors, etc.

The passive matrix dynamic drive field sequential color liquid crystal display in the present invention generally includes a liquid crystal display, a backlight source, a backlight driver and a liquid crystal display driver, and the backlight source is arranged on the bottom side of the liquid crystal display. The backlight source driver and the liquid crystal display driver respectively drive the structures of the backlight source and the liquid crystal display. The passive matrix dynamic drive field sequence color liquid crystal display TN, STN, HTN, OCB, any one of the non-bistable dynamic drive field sequence color liquid crystal display of VA type; the dynamic drive field sequence color liquid crystal display It is a dynamically driven field sequential color liquid crystal display whose frame rate can be adjusted between 45Hz and 200Hz.

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of the driving waveform principle of the positive display using 1/2 duty cycle driving according to the present invention. This embodiment is described by using a TN type passive matrix to dynamically drive a field sequential color liquid crystal display. It is the driving waveform of a TN-type positive display with two different color backlights, which dynamically drives a field sequential color liquid crystal display, and the reciprocal of the duty cycle of the driving waveform of the display is the same as the actual COM number of the display, which is 2 , which is driven with a 1/2 duty cycle; each COM in the same field (with the same color in the same field, the same below) is scanned; it can be seen from the figure that when we input a red drive from COM2 After the waveform, because a non-scanning area is set in the present invention, the rising area of the cyan light transmission intensity of COM2 is in the same cyan non-scanning area as COM1, and no longer enters the red area of the next frame, so the same picture is guaranteed The red color of COM1 is the same as that of COM2. This is the case for driving displays with a duty cycle of 1/2. For displays with other duty cycles, such as 1/3, 1/4...1/N, the same method can also be used, as long as it is satisfied: in the backlight In a non-bistable dynamic-driven field-sequential color liquid crystal display whose sources include at least two or more different colors, each COM in the same field is applied with a driving voltage in a certain order, and the sum of the scanning times of all driving waveforms is less than this The same effect can be achieved if the length of time that the color is on and the condition that the length of time that the color is on is equal to the sum of the scanning time of the driving waveform and the non-scanning time of the driving waveform. During the non-scanning time, we'd better set all the voltages between COM and SEG to OFF voltage or 0V. If we try to increase the number of scans of COM in the same color area, we find that it helps to reduce the degree of light leakage of unwanted colors. Also improves color uniformity. The reason why the sum of scanning time and non-scanning time of COM in each field is greater than or equal to the lighting time of the backlight in the same field is that the chromatic aberration can be properly corrected by adjusting the time difference. Therefore, the point of the backlight The bright time may be less than the sum of the scanning time and non-scanning time of COM. The above-mentioned driving method can be realized by designing a driving IC. For other duty ratios, such as the schematic diagrams of 1/3, 1/4...1/N, the present invention does not draw illustrations, obviously, those of ordinary skill in the industry can understand after reading the description of the present invention. In this embodiment, if the non-scanning time is equal to one COM scanning time, the effect is better, but this is related to the response speed of the liquid crystal. The non-scanning area in the embodiment shown in Figure 1 is located after the scanning time. In fact, adjust the phase difference between the start time of the color lamp in the same field and the start scanning time of COM1. The non-scanning area can also be located at the scanning time. previous. Fig. 2 is a schematic diagram of the driving waveform principle of the negative display driven by the 1/2 duty ratio of the present invention. The driving waveform of the negative display is not described in this document.

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of the principle of positive display driving waveforms for driving a display with a duty ratio of 1/3 with a driving wave of 1/4 duty ratio. This embodiment is an illustration of an HTN type positive display passive matrix dynamic drive field sequential color liquid crystal display. As shown in the figure, the passive matrix dynamic drive field sequence color liquid crystal display is a display with only three COMs, namely COM1, COM2 and COM3, which is a display with a 1/3 duty cycle. However, this In the invention, it is driven by a driver program of 1/4 duty cycle, so that COM1, COM2 and COM3 are all applied with voltage, and COM4 should be driven in the driver program of 1/4 duty cycle (not shown in the figure). ) driving waveform is not used, so that the last display period of 1/4 duty cycle is idle, and the idle COM4 display period constitutes a non-scanning area, so there is enough time to use To ensure that after COM3 is scanned, the rising area of its cyan light transmission intensity is in the same cyan area, so as to ensure that the red of COM1, the red of COM2, and the red of COM3 in the same picture are the same; this driving method is the most economical , you can directly select a driver chip with a 1/3 duty ratio to drive a display with 2 COMs; or use a driver chip with a 1/4 duty ratio to drive a display with 3 COMs; or use a 1/5 duty ratio driver chip to drive a display with 3 COMs; The driver chip to drive the display with 4 COMs, etc., and so on. In this case, each COM may be scanned multiple times in the same field, and the non-scanning time may be set multiple times. Of course, in the above-mentioned non-scanning area, we set all voltages between COM and SEG as OFF voltage. Preferably 0V. The driving waveform of the HTN type negative display dynamic drive field sequential color liquid crystal display is shown in Figure 4, which is similar to the HTN type positive display dynamic drive field sequential color liquid crystal display. In actual production, according to the response speed of the display liquid crystal, it is also possible to use a driver chip with a higher duty cycle of several levels to drive a display with a lower duty cycle. For example, a display with a 1/2 duty cycle can use a 1/2 duty cycle. 4. 1/5 duty cycle, or even a higher-level duty cycle driver chip to drive; another example, a 1/3 duty cycle display can be driven by a 1/5, 1/6 duty cycle, or even higher Level duty cycle driver chip to drive and so on.

Figure 3 reveals an example of a display with 3 COMs driven by a driver with a 1/4 duty cycle. In fact, a display with 2 COMs is driven by a driver with a 1/3 duty cycle. Driver; there are 4 COM displays, driven by a driver with a duty cycle of 1/5, and so on for other types, similar effects can be achieved. That is to say, as long as it satisfies: in the non-bistable dynamic drive field sequential color liquid crystal display with the backlight including at least two or more different colors, the reciprocal of the duty cycle of the driving waveform used in the same field is greater than the actual COM of the display The actual effect described in the present invention can be achieved under the condition that the display is driven by several numbers, and the last driving waveform in the driving waveforms is not used.

The backlight source in the present invention can adopt two or more different colors to combine, when adopting two different colors to combine, preferably use two kinds of complementary colors; The color combination of the most commonly used backlight source among the present invention is The three primary colors are red, green and blue.

In Fig. 1 to Fig. 4, two kinds of implementation modes of the present invention have been described respectively with the passive matrix dynamic drive field sequential color liquid crystal display of TN and HTN respectively, in fact, other types of dynamically driven field sequential color liquid crystal display, such as STN , OCB, VA and other non-bistable dynamic drive field sequential color liquid crystal displays can be driven by the method of the present invention, and the same effect can be achieved.

Claims (8)

1. A driving method for a dynamically driven field-sequential color liquid crystal display, characterized in that, using the progressive scanning method to dynamically drive, its backlight source comprises at least two passive matrix dynamic driving field-sequential color liquid crystal displays of different colors , the reciprocal of the duty cycle of the driving waveform of the passive matrix dynamically driving the field sequential color liquid crystal display is equal to the actual COM number of the display, or the duty cycle of the driving waveform of the passive matrix dynamically driving the field sequential color liquid crystal display The reciprocal of the ratio is greater than the actual COM number of the display. The row scanning method of the passive matrix dynamic drive field sequence color liquid crystal display is that each COM in the same field is applied with a driving voltage in a certain order, and the polarity of the driving voltage is Inverting at least once adds non-scanning time within each field in addition to COM's scanning time. 2 . The driving method for dynamically driving a field sequential color liquid crystal display according to claim 1 , wherein the non-scanning time is placed before or after the scanning time. 3 . 3. The driving method for dynamically driving a field sequential color liquid crystal display according to claim 1 or 2, wherein the sum of the scanning time and the non-scanning time of the COM in each field is greater than or equal to that of the backlight source in the same color zone Light up the time. 4. according to the driving method of claim 1 or 2 described dynamic drive field sequential color liquid crystal display, it is characterized in that, no matter described liquid crystal display is in positive display mode or negative display mode, all COM and SEG between non-scanning time voltage is OFF or zero. 5. The driving method for dynamically driving a field sequential color liquid crystal display according to claim 1 or 2, wherein the passive matrix dynamic driving field sequential color liquid crystal display is a dynamic driving method with a frame rate between 45Hz and 200Hz Field sequential color liquid crystal display. the 6. according to the driving method of claim 1 or 2 described dynamic driving field sequential color liquid crystal display, it is characterized in that, described passive matrix dynamic driving field sequential color liquid crystal display is TN, STN, HTN, OCB, VA class Non-bistable dynamically driven field-sequential color liquid crystal displays. 7. The driving method for dynamically driving a field sequential color liquid crystal display according to claim 1 or 2, wherein when the color of the backlight source is two colors, the two colors are complementary colors; or, the The colors of the backlight are red, green and blue. 8. according to the driving method of claim 1 or 2 described dynamic drive field sequential color liquid crystal display, it is characterized in that, described passive matrix dynamic driving field sequential color liquid crystal display comprises liquid crystal display screen, backlight source, backlight source driver and LCD driver, the backlight is arranged on the bottom side of the LCD, the backlight driver and the LCD driver respectively drive the backlight and the LCD. the

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