The odd scanning circuit 302 and the even scanning circuit 304 scan odd-numbered rows of pixels 308a and even-numbered rows of pixels 308b in the N rows of pixels 308 through the odd scan lines 310a and the even scan lines 310b, respectively, wherein the scan time of each scan line is equal to a pixel scanning time TS. The scan line driving method according to the invention is applied to the liquid crystal display 300. The detailed implementing methods of the invention will be described with reference to the following three embodiments.
As shown in
The liquid crystal display 300 includes an odd frame scanning period and an even frame scanning period due to the inversion of the data voltage polarity. In the odd frame scanning period, the odd-numbered rows of pixels 308a are in a charge state and the even-numbered rows of pixels 308b are in a discharge state. In the even frame scanning period, the odd-numbered rows of pixels 308a are in the discharge state and the even-numbered rows of pixels 308b are in the charge state. The odd-numbered rows of pixels 308a and the even-numbered rows of pixels 308b have different data voltage polarities, and the polarity of the pixel data is changed every two frame scanning periods. This liquid crystal display 300 is preferable a row inversion liquid crystal display.
The embodiment divides the pixel scanning times TS of the odd scan lines 310a and the even scan lines 310b of the N scan lines 310 so that the enabled times of the scan signal SD1′ in the odd frame scanning period and the even frame scanning period are respectively a charge time TC and a discharge time TD, and the enabled times of the scan signal SD2′ in the odd frame scanning period and the even frame scanning period are the discharge time TD and the charge time TC, respectively.
The scan signals SD1′ and SD2′ change the length of the enabled time once every one frame scanning period with the changes of the charge states or the discharge states of the odd-numbered rows of pixels 308a and the even-numbered rows of pixels 308b. This charge time is equal to 4/3 times of the pixel scanning time TS, and the discharge time is equal to 2/3 times of the pixel scanning time TS.
First, step 602 enables the first scan line in the charge time to drive the first row of pixels to charge.
Then, step 604 enables the second scan line in the discharge time to drive the second row of pixels to discharge.
Next, step 606 enables the first scan line in the discharge time to drive the first row of pixels to discharge.
Then, step 608 enables the second scan line in the charge time to drive the second row of pixels to charge.
This embodiment divides the pixel scanning times of the N scan lines 310 according to the charge/discharge states of the N rows of pixels 308. Thus, this embodiment lengthens the operation times of the N/2 rows of pixels 308 in the charge states so that the rows of pixels 308 may be sufficiently charged to the set voltage, and shortens the operation times of the N/2 rows of pixels in the discharge states so that the sum of the pixel scanning times of the N scan lines 310 is kept constant. This embodiment may also be applied to the typical single-side scanning circuit, or other liquid crystal displays.
The scan line driving method according to the first embodiment of the invention can shorten the discharge times of the rows of pixels of the liquid crystal display so as to enhance the operating efficiency of the pixel and to lengthen the charge times of the rows of pixels. Thus, the problem of the incorrect data voltage level or the reduction of the aperture ratio due to the increase of the size of the TFT in the conventional liquid crystal display can be solved.
The difference between the second embodiment and the first embodiment is that the scan signals SD1 and SD2″ of the second embodiment and the scan signals SD1′ and SD2′ of the first embodiment have different timing waveforms. As shown in
The scan signals SD1″ and SD2″ control the odd-numbered rows of pixels 308a and the even-numbered rows of pixels 308b through the odd scan lines 310a and the even scan lines 310b to drive the N rows of pixels 308 to achieve the pre-charge and pre-discharge effects. This liquid crystal display 300 is a two-row inversion liquid crystal display.
For example, the predetermined voltage setting time TP is equal to the pixel scanning time TS, and the odd scan time T1 and the even scan time T2 are shorter than the pixel scanning time TS. A sum of the predetermined voltage setting time TP, the odd scan time T1 and the even scan time T2 is preferably smaller than a sum of two pixel scanning times TS. In addition, a difference between the sum of the predetermined voltage setting time TP, the odd scan time T1 and the even scan time T2 and the sum of the two pixel scanning times TS is equal to a saved time TR. The actual applications of the scan signals SD1″ and SD2″ will be described with reference to the accompanying drawing.
In the predetermined voltage setting time TP, the scan signals SD1″ and SD2″ are enabled so that the odd-numbered rows of pixels 308a and the even-numbered rows of pixels 308b are enabled respectively through the odd scan lines 310a and the even scan lines 310b. At this time, the data driver 306 outputs the higher data voltage between the data voltages V1 and V2. In
In the odd scan time T1, the scan signal SD1″ is enabled so as to enable the odd-numbered rows of pixels 308a through the odd scan lines 310a. At this time, the data driver 306 outputs the data voltage V1 to charge the storage capacitors of the odd-numbered rows of pixels 308a to 10 volts. In the even scan time T2, the scan signal SD2″ is enabled to enable the even-numbered rows of pixels 308b through the even scan lines 310b. At this time, the data driver 306 outputs the data voltage V2 to discharge the storage capacitors of the even-numbered rows of pixels 308b to 5 volts.
The above-mentioned descriptions are made according to the pixel voltage with the scanning period of the positive voltage frame in the driving waveforms of
In the predetermined voltage setting time TP, the scan signals SD1″ and SD2″ are enabled to enable the odd-numbered rows of pixels 308a and the even-numbered rows of pixels 308b through the odd scan lines 310a and the even scan lines 310b, respectively. At this time, the data driver 306 outputs the higher data voltage between the data voltages V1′ and V2′. The higher data voltage discharges the storage capacitors of the odd-numbered rows of pixels 308a and the even-numbered rows of pixels 308b simultaneously. In this embodiment, the higher data voltage between the data voltages V1′ and V2′ is the data voltage V1′, which is 5 volts. Thus, the pixel voltages SR1′ and SR2′ are discharged from 10 and 5 volts to 5 volts.
In the odd scan time T1, the scan signal SD1″ is enabled to enable the odd-numbered rows of pixels 308a through the odd scan lines 310a. At this time, the data driver 306 outputs the data voltage V1′ to discharge the storage capacitors of the odd-numbered rows of pixels 308a. At this time, the pixel voltage SR1′ is discharged from 5 volts to 0 volts. In the even scan time T2, the scan signal SD2″ is enabled to enable the even-numbered rows of pixels 308b through the even scan lines 310b. At this time, the data driver 306 outputs the data voltage V2′ to continuously discharge the storage capacitors of the even-numbered rows of pixels 308b to 5 volts.
The liquid crystal display 300 of this embodiment is a normal white display, for example. Although this embodiment is illustrated by taking the dual-side scanning circuit including the odd scanning circuit 302 and the even scanning circuit 304 as an example. However, the scan line driving method of this embodiment may also be applied to the typical single-side scanning circuit, or other liquid crystal displays.
This embodiment divides every two pixel scanning times TS of the N scan lines 310 of the liquid crystal display 300 into the predetermined voltage setting time TP, the odd scan time T1 and the even scan time T2. The N scan lines 310 are paired according to the method of dividing the scan times TS in order to finish the scanning of the corresponding two rows of pixels in the predetermined voltage setting time TP, the odd scan time T1 and the even scan time T2. Thus, the effect of shortening the scan times of the rows of pixels can be achieved. The shortened scan time of two rows of pixels is equal to the saved time TR.
First, step 1002 divides the pixel scanning times of the first scan line and the second scan line into a predetermined voltage setting time, an odd scan time and an even scan time.
Next, step 1004 enables the first scan line and the second scan line in the predetermined voltage setting time to make the voltages of the first row of pixels and the second row of pixels be equal to a first voltage. The first voltage is the higher one of the data voltages of the first row of pixels and the second row of pixels.
Furthermore, step 1006 enables the first scan line and the second scan line in the first scan time and the second scan time, respectively. The first scan line and the second scan line input the corresponding data voltages to the first row of pixels and the second row of pixels, respectively.
Then, step 1008 enables the first scan line and the second scan line in the predetermined voltage setting time to make the voltages of the first row of pixels and the second row of pixels equal to a second voltage. The second voltage is the higher one of the data voltages of the first row of pixels and the second row of pixels.
Furthermore, step 1010 enables the first scan line and the second scan line in the first scan time and the second scan time, respectively. The first scan line and the second scan line input the data voltages to the first row of pixels and the second row of pixels, respectively.
Thereafter, step 1012 repeats steps 1002 to 1010.
The scan line driving method according to the embodiment of the invention utilizes the pre-charge and pre-discharge methods to shorten the operation times for charging and discharging the data voltages of the liquid crystal display. Thus, the conventional problem of the incorrect data voltage level caused by the insufficient charge time of the data voltage in the conventional liquid crystal display or the reduction of the aperture ratio caused by the increase of the size of the TFT can be solved.
Scan signals SD1′″ and SD3′″ are generated by the odd scanning circuit 302, and scan signals SD2′″ and SD4′″ are generated by the even scanning circuit 304. The scan signals SD1′″ and SD3′″ control the first row of pixels and the third row of pixels in the odd-numbered rows of pixels 308a through the first scan line and the third scan line of the odd scan lines 310a, respectively. The scan signals SD2′″ and SD4′″ control the second row of pixels and the fourth row of pixels in the even-numbered rows of pixels 308b through the second scan line and the fourth scan line of the even scan lines 310b, respectively.
This embodiment divides the pixel scanning times TS of four neighboring scan lines into a predetermined voltage setting time TP′, and scan times T1′, T2′, T3′ and T4′. The scan signals SD1′″ to SD4′″ are enabled in the predetermined voltage setting time TP′. The scan signals SD1′″ to SD4′″ are enabled in the scan times T1′ to T4′, respectively. The predetermined voltage setting time TP′, the scan time T1′, the scan time T2′, the scan time T3′ and the scan time T4′ do not overlap with one another.
Each of the scan times T1′ to T4′ is shorter than the pixel scanning time TS, and the sum of the predetermined voltage setting time TP′ and the scan times T1′ to T4′ is shorter than the sum of four pixel scanning times TS. The difference between the sum of the predetermined voltage setting time TP′ and the scan times T1′ to T4′ and the sum of the four pixel scanning times TS is a saved time TR′. The actual application of the scan signals SD1′″ to SD4′″ in the liquid crystal display is described in the following drawings.
In the predetermined voltage setting time, the first scan line to the fourth scan line are enabled. At this time, the data driver 306 outputs the highest one of the data voltages V1″ to V4″. The highest data voltage charges the storage capacitors of the first to fourth rows of pixels. At this time, the pixel voltages SR1″ to SR4″ are charged from 0 volts to 10 volts.
The first to fourth scan lines are respectively enabled in the first to fourth scan times. At this time, the first to fourth scan lines charge the storage capacitors of the first to fourth rows of pixels according to the data voltages V1″ to V4″ outputted from the data driver 306, respectively. The pixel voltages SR1″ to SR4″ are driven by the data voltages V1″ to V4″ to charge or discharge to 5 volts, 10 volts, 5 volts and 10 volts, respectively.
The liquid crystal display 300 is a normal white display, for example. The odd-numbered rows of pixels 308a form the white frame, and the even-numbered rows of pixels 308b form the black frame. This liquid crystal display is a four-row inversion liquid crystal display, for example.
This embodiment divides four pixel scanning times TS of every four scan lines of the N scan lines 310 of the liquid crystal display 300 into a predetermined scan time PT′ and scan times T1′ to T4′. Four of the N scan lines 310 are grouped according to the method of dividing the scan times TS so that the corresponding four rows of pixels are scanned in the predetermined scan time PT′ and the scan times T1′ to T4′ and the effect of shortening the scanning times of the rows of the pixels can be achieved.
First, step 1302 divides the N pixel scanning times of the N scan lines into a predetermined voltage setting time and N data input times, wherein N is a natural number greater than 1.
Then, step 1304 enables the N scan lines in the predetermined voltage setting time to make the voltages of the N rows of pixels be equal to a predetermined voltage.
Furthermore, step 1306 enables the N scan lines in the N data input times so as to input the corresponding data voltages to the N rows of pixels.
Thereafter, step 1308 repeats steps 1302 to 1306.
The scan line driving method according to the embodiment of the invention enables all scan lines of the liquid crystal display in the predetermined voltage setting time so as to set the voltages of the rows of pixels of the liquid crystal display to a predetermined voltage. Thus, it is possible to shorten the operation times for charging and discharging the data voltages of the liquid crystal display, and thus to solve the problem of the incorrect data voltage level caused by the insufficient charge time in the conventional liquid crystal display, or the problem of the reduction of the aperture ratio caused by the increase of the size of the TFT.
While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.
Number | Date | Country | Kind |
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95131192 | Aug 2006 | TW | national |