Computer graphics processing and selective visual display system – Display driving control circuitry
Reexamination Certificate
1997-11-25
2001-05-01
Shankar, Vijay (Department: 2673)
Computer graphics processing and selective visual display system
Display driving control circuitry
C345S182000, C345S103000, C348S458000
Reexamination Certificate
active
06225990
ABSTRACT:
DESCRIPTION
1. Field of the Invention
The present invention relates to a method of driving a display apparatus which has a plurality of scanning lines and which supplies image signals for a number of scanning lines smaller than the foregoing number of scanning lines to display elements. Further, the present invention relates to a display apparatus using the driving method.
Furthermore, the present invention relates to an electronic apparatus using the display apparatus.
2. Background Technology
In an image display apparatus for displaying image signals of the NTSC system, hitherto, image signals are standardized in such a way that 525 scanning lines form one screen. Therefore, as a display apparatus for displaying these image signals, a display apparatus is used having the above-described 525 scanning lines in the vertical direction of the screen.
Meanwhile, in recent years, in response to increased needs of the user, display apparatuses having 525 or more scanning lines have been developed one after another. However, for image signals of an interlace (interlaced scanning) system in the NTSC system, the image signals of one frame are formed by the interlaced scanning of the image signals of a first field and the image signals of a second field, and the number of effective scanning lines of the image signals of one field is as small as approximately 220. Therefore, the number of scanning lines of the image signals of one field is smaller than the number of scanning lines (525 or more) of the display apparatus. Hence, there are drawbacks in that the image signals cannot be supplied periodically to the whole of the scanning lines, i.e., all of the pixels.
If the image signals are supplied to only the number of scanning lines corresponding to the image signals among the whole of the scanning lines of an image display apparatus, an image is displayed only on a part of the screen. Therefore, even though the display apparatus has a number of pixels (a number of scanning lines) for high resolution, they all cannot be utilized.
Further, in an image display apparatus such as a liquid-crystal device, when image signals such that one field is formed of 220 scanning lines are interlace-scanned and supplied, the cycle of supply of the image signals to each pixel becomes a one-frame cycle, causing flicker to occur.
The present invention has been achieved in view of such circumstances. It is an object of the present invention to provide a display apparatus capable of periodically supplying image signals to the pixels of the entire screen even when the number of scanning lines of the screen is greater than the number of scanning lines of the image signals.
SUMMARY OF THE INVENTION
In a first aspect, there is provided a method of driving a display apparatus in accordance with the present invention which has a plurality of scanning lines and which supplies image signals for a number of scanning lines smaller than the number of the plurality of scanning lines to display elements controlled by the plurality of scanning lines,
wherein the image signals of each scanning line are supplied to display elements controlled by N (N is an integer) scanning lines of the display apparatus, respectively, and
within one vertical scanning period, the number N of scanning lines corresponding to the display elements to which the same image signals are supplied is changed according to the sequence number of the scanning lines of the image signals.
Further, in a second aspect of the present invention, there is provided a method of driving a display apparatus which has a plurality of scanning lines and which supplies image signals for a number of scanning lines smaller than the number of the plurality of scanning lines to display elements controlled by the plurality of scanning lines, the method comprising the steps of:
storing the image signals of each scanning line in storage means;
reading the same image signals for one scanning line stored in the storage means N times (N is an integer) within one horizontal scanning period;
supplying the same image signals read N times to display elements controlled by N scanning lines of the display apparatus; and
changing the number N of times of reading within one vertical scanning period.
Further, in a third aspect of the present invention, there is provided a display apparatus which has a plurality of scanning lines and which supplies image signals for a number of scanning lines smaller than the number of the plurality of scanning lines to display elements controlled by the plurality of scanning lines,
the display apparatus comprising:
storage means for storing image signals corresponding to a number of scanning lines smaller than the number of the plurality of scanning lines at least by an amount corresponding to one scanning line;
control means for reading image signals for one scanning line stored in the storage means N times (N is an integer); and
driving means for supplying the same image signals read by the control means N times to display elements controlled by N scanning lines,
wherein the number N of times in which the image signals are read from the storage means is changed within one vertical scanning period.
Further, there are two types of numbers N of scanning lines corresponding to display elements to which the same image signals are supplied within one vertical scanning period, and the two types are switched according to the sequence number of the scanning lines of the image signals read from the storage means.
As a result of the above, even if the number of scanning lines of the image signals within one vertical scanning period (one field or one frame) is smaller than the number of all the scanning lines of a liquid-crystal panel, it is possible to select all of the scanning lines. Therefore, it is possible to perform a display fully utilizing the functions of the high-resolution display apparatus. Further, since, by changing N, the image signals for the effective scanning lines of the image signals to be displayed are displayed using all of the scanning lines on a display apparatus, there is no need to thin out the scanning lines of the image signals, and it is possible to perform a reproduction display utilizing the original image information to its fullest extent. Further, if N is of two values and it can be switched in accordance with a predetermined rule, the circuitry of the control means becomes easy.
Further, if expressed by general equations, the values of N become the values N1, N2, . . . Ni (i is an integer of 2 or more) which satisfy all the following equations (1), (2) and (3),
L=M1+M2+ . . . +Mi (1)
Hm=N1×M1+N2×M2+ . . . +Ni×Mi (2)
L<Hm (3)
L: the number of effective scanning lines of the image signals within one vertical scanning period
Hm: the number of effective scanning lines of the display apparatus
Ni: the number of scanning lines of the display apparatus, selected to supply the same image signals for one scanning line to the display elements
Mi: the number of scanning lines of the image signals within one vertical scanning period, which the same image signals for said scanning line are generated Ni times.
Further, to be specific, in order to cause a SVGA display apparatus to perform a display, L is set to 220, Hm is set to 600, N1 is set to 3, N2 is set to 2, M1 is set to 160, and M2 is set to 60.
Further, a method of varying the number N of scanning lines corresponding to the display elements to which the same image signals are supplied within one vertical scanning period is changed at each vertical scanning period.
To be more specific, there are two types of numbers N of scanning lines corresponding to the display elements to which the same image signals are supplied within one vertical scanning period, these two types are selected according to the sequence number of the scanning lines of the image signals, and this selection method is further switched at each vertical scanning period.
As a result of the above, a part of the whole of an i
Aoki Toru
Shimotome Nobuyuki
Oliff & Berridg,e PLC
Said Mansour M.
Seiko Epson Corporation
Shankar Vijay
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