JPH06308455A - Method for driving liquid crystal display device - Google Patents

Abstract

PURPOSE:To display the display data of a personal computer with 400 lines of scanning signal on a liquid crystal display device with 480 lines of scanning signal capable of supplying a driving current to a liquid crystal without applying a load to a source driver and suppressing the driving power to 1/40 compared with the driving method of the usual liquid crystal display device, and further, without adding a specific structure as a mode selection means to a gate driver. CONSTITUTION:This method is the method for driving the liquid crystal display device supplying the scanning signals G0-G479 to plural scanning signal lines and supplying an image signal to plural image signal lines provided so as to intersect with the scanning signal lines, and the scanning signals are supplied successively to a set of the scanning signal lines G0-G39 of an upper end side and the scanning signal lines G440-G479 of a low end side among the scanning signal lines, and thereafter, the scanning signals are supplied successively to the scanning lines G40-G439 of a central part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a liquid crystal display device, and more particularly to a method for driving a liquid crystal display device having blank areas on the upper and lower sides of a display image.

[0002]

2. Description of the Related Art When displaying data of a personal computer on a display device such as a CRT, one vertical scanning period of the display data is 17.72 ms and one horizontal scanning period is 40.28 μs. In addition, there are 400 vertical scanning lines of a personal computer, and these 400 lines are scanned in 16.11 ms (effective display period) to obtain 1.61 ms (17.72-16.1).
1) is the return line period.

On the other hand, the number of scanning signal lines of the liquid crystal display device is four.
There are 80 lines. Considering the case where the display data of the above personal computer is displayed on the liquid crystal display device, 17.72 ms / 4
Since 0.28 μs = 440, even if scanning is performed without providing a blanking period, only 440 scanning signal lines can be scanned.

Therefore, conventionally, as shown in FIG. 3, among the 480 scanning signal lines of the liquid crystal display device, the display data of the personal computer is displayed in the effective display area at the center of the screen,
This has been dealt with by providing black display areas at the upper and lower ends of the screen. That is, the scanning signal lines of 40 lines above the screen and the scanning signal lines of 40 lines below the screen are black display regions, and the scanning signal lines of 400 lines in the center of the screen are effective display regions. The display data of the personal computer is displayed on the scanning signal line.

When performing such display, scanning signals are supplied to the 480 scanning signal lines at the timing shown in FIG. In FIG. 3, V-START is a vertical scanning start signal, SCLK is a clock signal, and G _{0 to} G _479.
Is a scanning signal. Of the scanning signals G _{0 to} G ₄₇₉ , G ₀
-G ₃₉ and G ₄₄₀ -G ₄₇₉ are scanning signals for the black display region, and G ₄₀ -G ₄₃₉ are scanning signals for the effective display region.

Immediately before the effective display period of the blanking period, G _{0 to} G ₃₉ and G _{440 to} G _{479 are} added to the scanning signal lines in the black display area.
The scanning signal of 1 is given at once to display black on the upper and lower ends of the screen. After the scanning of the scanning signal lines in the black display area is completed, the scanning signal lines in the effective display area are supplied with scanning signals of G _{40 to} G ₄₃₉ to perform sequential scanning (for example, JP-A-4-788).
23).

[0007]

However, in this conventional method of driving a liquid crystal display device, since 80 lines of the black display area are simultaneously scanned, the driving capability of the source driver (not shown) is set to 80 lines at the same time. The output current required for charging is required. If the source driver cannot satisfy the capability, it is necessary to provide a buffer in the subsequent stage of the source driver. In addition, when 80 lines in the black display area are simultaneously scanned and 400 lines in the effective display area are set to 1
Since the operation of the gate driver is basically different from the case of scanning line by line, there is a problem that a mode selecting means for switching the operation is required for the gate driver.

The present invention has been made in view of the above problems of the prior art, and displays the display data of a personal computer having only 400 scanning signals on a liquid crystal display device having 480 scanning signal lines. Even in this case, it is an object of the present invention to provide a driving method of a liquid crystal display device capable of displaying without special work on the source driver and the gate driver.

[0009]

According to a method of driving a liquid crystal display device of the present invention, a scanning signal is supplied to a plurality of scanning signal lines, and a plurality of image signal lines provided to intersect the scanning signal lines. In the method of driving a liquid crystal display device for supplying an image signal to, in the scanning signal line,
It is characterized in that a scanning signal line on the upper end side and a scanning signal line on the lower end side are combined to supply a sequential scanning signal, and then the central scanning signal line is supplied with the sequential scanning signal. Is achieved.

[0010]

With the above arrangement, during the blanking period of the scanning signal, 40 lines on the upper end side and 40 lines on the lower end side can be sequentially set to 40 sets and sequentially scanned, and 400 lines in the central part can be used.
480 lines in the scanning period for 440 lines
The scanning signal line can be scanned. Also, 40 on the upper end side
Since 40 sets of lines and 40 lines on the lower end side are sequentially scanned, the source driver is not burdened and the charging current can be supplied without providing a buffer or the like.

[0011]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows a configuration example of a liquid crystal display device.
In this liquid crystal display device, scanning signal lines G _{0 to} G ₄₇₉ and image signal lines S _{0 to} S ₆₃₉ are provided so as to intersect with each other, and scanning signal lines G _{0 to} G ₄₇₉ and image signal lines S _{0 to} S ₆₃₉ intersect with each other. The TFT 1, the pixel electrode 2, and the additional capacitor 3 are provided in the. The scanning signal line G ₀ ~G _479, the scanning signal G ₀ ~G ₄₇₉ from the gate driver 4 is supplied,
Image signals S _{0 to} S ₆₃₉ are supplied from the source driver 5 to the image signal lines S _{0 to} S ₆₃₉ . The gate driver 4 is composed of a 480-bit shift register (not shown). The source driver 5 is composed of a 640-bit shift register (not shown) and a sample hold circuit (not shown). Image signal _{VIDEO SIG.}
Clock signal _{DOT CLOCK} , horizontal scanning start signal _H-STARTGA
Is entered. Further, the gate driver 4 has a vertical scanning start signal _V-START and a horizontal scanning start signal of the source driver 5.
A clock signal _sclk synchronized with _H-STARTGA is input.

FIG. 2 shows an input / output waveform timing chart of the gate driver 4. Incidentally, at the timing when the SCLK signal rises, successively image signals to the image signal lines S ₀ ~S ₆₃₉ S ₀ ~S ₆₃₉ is supplied. In FIG. 2, G _{0 to} G
₄₇₉ is a scanning signal supplied to each scanning signal line,
G _{0 to} G ₃₉ and G _{440 to} G ₄₇₉ are scanning signals for the black display region, and G _{40 to} G ₄₃₉ are scanning signals for the effective display region. The scanning signals G _{40 to} G ₄₃₉ of the effective display area are sequentially scanned downward. The scanning signals G _{0 to} G ₃₉ and G _{440 to} G ₄₇₉ of the black display area scan every two lines. That is,
The scan signal G ₀ and the scan signal G ₄₄₀ scan at the same timing, the scan signal G ₁ and the scan signal G ₄₄₁ scan at the same timing delayed by one clock, and the scan signal G ₂ and the scan signal line G ₄₄₂ further scan. Scan at the same timing delayed by one clock. Hereinafter, similarly, the scanning signal is supplied so that the scanning signal for the black display region on the upper end side and the scanning signal for the black display region on the lower end side are sequentially scanned every two lines. As a result, 480 scanning signal lines can be scanned during the scanning period of 440 lines, and the shortage of 40 lines can be compensated.

Further, in order to obtain a display screen as shown in FIG. 3, the timing of the V-START pulse is defined as follows. One vertical scanning period is 17.72 msec, one horizontal scanning period is 40.28 μsec, and the number of effective display data is 400 (vertical) × 640 (horizontal) display mode of the personal computer. The V-START pulse is input so that the scanning signal G ₀ becomes active in accordance with the output after the blank signal (valley of SCLK) immediately after the effective display period in FIG. 2 is sampled by the source driver 5.
As a result, 40 lines of the scanning signals G _{0 to} G ₃₉ are sequentially activated, while black display is performed on the panel by utilizing the blanking period. Next, the scanning signals G _{40 to} G ₄₃₉ are sequentially activated, but during this period, the effective display period appears, so an effective display screen appears on the panel. Then G ₄₄₀
Is activated, but at the same time G ₀ is activated again, the V-START pulse is input to the gate driver. As a result, G _{440 to} G ₄₇₉ are sequentially activated, and at the same time, G _{0 to} G ₃₉ are sequentially activated again. During this period, it is a blanking period and is displayed in black. By repeating this, the display screen of FIG. 3 is obtained.

[0014]

As described above, according to the driving method of the liquid crystal display device of the present invention, among the scanning signal lines, the scanning signal line on the upper end side and the scanning signal line on the lower end side are combined and sequentially. The scan signal is supplied, and then the scan signal is sequentially supplied to the scan signal line in the central portion. Therefore, 40 lines on the upper end side and 40 lines on the lower end side are sequentially set to 40 sets during the blanking period of the scan signal. It is possible to scan, and in the scanning period of 440 lines including 400 lines in the central part,
480 scan signal lines can be scanned. In addition, since the scanning signal line on the upper end side and the scanning signal line on the lower end side are sequentially scanned, for example, every two lines, the source driver is not burdened, and the charging current can be supplied without providing a buffer or the like. As compared with the driving method of the liquid crystal display device, the driving capability of the source driver can be suppressed to 1/40. Further, since the scanning signal is sequentially supplied to each scanning signal line, the scanning signal scans the display data of the PC for 400 lines without adding a special structure such as a mode selecting means to the gate driver. The signal can be displayed on a liquid crystal display device having 480 lines.

[Brief description of drawings]

FIG. 1 is a configuration example of a liquid crystal display device.

FIG. 2 is a timing chart showing a driving method of a liquid crystal display device according to the present invention.

FIG. 3 is an example of a display screen of a liquid crystal display device.

FIG. 4 is a timing chart showing a driving method of a conventional liquid crystal display device.

[Explanation of symbols]

G _{0 to} G ₄₇₉ ... Scanning signal (line) S _{0 to} S ₆₃₉ ... Image signal (line) 1 ... TFT 2 ... Pixel electrode 3 ... Additional capacitance

Claims (1)

[Claims] 1. A method for driving a liquid crystal display device, wherein a scanning signal is supplied to a plurality of scanning signal lines and an image signal is supplied to a plurality of image signal lines provided intersecting the scanning signal lines. Among the signal lines, the scanning signal line on the upper end side and the scanning signal line on the lower end side are combined to sequentially supply the scanning signal, and then the central scanning signal line is sequentially supplied with the scanning signal. Driving method for liquid crystal display device.