Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-10-19
2001-10-16
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C100S127000, C100S09800R
Reexamination Certificate
active
06304242
ABSTRACT:
TECHNICAL FIELD
This invention relates to an image displaying method and device for sequentially sampling an input video signal to display an image in an effective display area having an aspect ratio of X/Y (X: width, Y: height).
BACKGROUND ART
Liquid-crystal display devices have been used in various fields as typical display devices for personal computers and word processors, as display devices for television sets and car navigation systems, and further for projection-type display devices, because of their thinness, lightness, and low power consumption. Specifically, active-matrix liquid-crystal display devices have display pixels electrically connected to switching elements, and research and development thereof have been made actively because they provide good display images without crosstalk between adjacent pixels.
In recent years, display devices having the effective display area with an aspect ratio of 4/3 have been being replaced with display devices having the effective display area elongated in the direction of horizontal scanning line, such as the effective display area with an aspect ratio of 16/9. This aspect ratio provides the user with a visually wide screen.
There have been several methods of causing a liquid-crystal display device having the effective display area with an aspect ratio of 16/9 to display the video signal having image information with an aspect ratio of 4/3.
For example, one known method is to sample sequentially the video signal Video with an aspect ratio of 4/3 shown in
FIG. 12A
sequentially all over the effective display area with an aspect ratio of 16/9 on the basis of a specific sampling clock and display the result as shown in FIG.
12
B. With this method, a special circuit configuration is not needed, but the aspect ratio of the video signal with an aspect ratio of 4/3 is not be reproduced faithfully, which results in the image elongated in the direction of horizontal scanning line as shown in FIG.
12
B.
Hereinafter, a method of displaying the video signal all over the effective display area is referred to as the full display mode.
Another known method is to divide the effective display area with an aspect ratio of 16/9 into a display area with an aspect ratio of 4/9 and a display area with an aspect ratio of 12/9 (=4/3) as shown in
FIG. 12C
or
12
D and display the video signal Video having image information with an aspect ratio of 4/3 in the display area with an aspect ration of 12/9 (=4/3). Hereinafter, this display method is referred to as the left-aligned or right-aligned mode, depending on the display position.
With this method, however, since the sampling period corresponding to the display area with an aspect ratio of 12/9 (=4/3) requires at least 0.8 H for one horizontal scanning period (1 H) in the NTSC system, the sampling period corresponding to the display area with an aspect ratio of 4/9 is 0.2 H or less. Therefore, the video signal has been sampled sequentially and displayed on the basis of the video signal previously image-processed all over the effective display area by image processing techniques using a frame memory. This has prevented the device from being produced at low cost.
Under the circumstances, in Japanese Patent Application No. 9-227656, the applicant has proposed a device and method for realizing the above display easily by making the frequency of the sampling clock different in each horizontal scanning period. This display method requires no frame memory.
Furthermore, as shown in
FIG. 13A
, it is needed to divide the effective display area having an aspect ratio of 16/9 into a display area having an aspect ratio of 2/9 and a display area having an aspect ratio of 12/9 (=4/3), and display the video signal Video whose image information has an aspect ratio of 4/3 in the display area having an aspect ratio of 12/9 (=4/3) in such a manner the image is located in the center.
As shown in
FIGS. 13B
to
13
D, the following display modes are needed: the left-aligned/full composite display mode, a combination of the left-aligned display mode and full display mode; the right-aligned/full composite display mode, a combination of the right-aligned display mode and full display mode; and the centering/full composite display mode, a combination of the centering display mode and full display mode.
Furthermore, as shown in
FIG. 13E
, the following display modes are needed: the irregular composite display mode obtained by combining the centering display mode with the full display mode irregularly (hereinafter, referred to as the centering/full irregular composite display mode); the irregular composite display mode (not shown) obtained by combining the left-aligned display mode with the full display mode (hereinafter, referred to as the left-aligned/full irregular composite display mode); and the irregular composite display mode obtained by combining the right-aligned display mode with the full display mode (hereinafter, referred to as the right-aligned/full irregular composite display mode).
In the composite display mode and irregular composite display mode, because the drive timing differs from area to area, for example, in the horizontal select period or polarity inverting timing, it has been difficult to display images without carrying out a special image process.
DISCLOSURE OF INVENTION
In view of the disadvantages described above, it is an object of the present invention to provide an image displaying method and device operable in various display modes such as composite or irregular composite display modes.
According to the present invention, there is provided an image displaying method for displaying an image on a display panel which is composed of signal lines and scanning lines crossing at right angles, pixel electrodes arrayed via switching elements near the intersections of the signal lines and scanning lines, a counter electrode facing the pixel electrodes, and an optical modulation layer arranged between the pixel electrodes and the counter electrode, wherein the image displaying method comprises the steps of: sequentially outputting a scanning pulse to the scanning lines to conduct between the signal lines and the pixel electrodes during a horizontal select period; sequentially sampling a video signal including more than one horizontal scanning period in a vertical scanning period for each specific period of the horizontal select period; and outputting the resulting pixel signal voltages to the signal lines while outputting a counter electrode voltage to the counter electrode; the image displaying method further comprises the step of: in a case where the vertical scanning period includes a first vertical scanning period for displaying of the pixel signal voltages sequentially sampled over a first period shorter than the horizontal scanning period of the video signal, and a second vertical scanning period for displaying of the pixel signal voltages sequentially sampled over a second period substantially equal to the horizontal scanning period, causing the horizontal select period to be synchronized with the second period of the second vertical scanning period.
Furthermore, according to the present invention, there is provided an image displaying device comprising: a display panel which is composed of signal lines and scanning lines crossing at right angles, pixel electrodes arrayed via switching elements near the intersections of the signal lines and scanning lines, a counter electrode facing the pixel electrodes, and an optical modulation layer arranged between the pixel electrodes and the counter electrode; a scanning line driving circuit for sequentially outputting a scanning pulse to the scanning lines to conduct between the signal lines and the pixel electrodes during a horizontal select period; a signal line driving circuit for sequentially sampling a video signal including more than one horizontal scanning period in a vertical scanning period for each specific period of the horizontal select period and outputting the resulting pixel signal voltages to the signal li
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Said Mansour M.
Shalwala Bipin
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