Television – Basic receiver with additional function – Multimode
Patent
1995-12-28
1998-02-17
Hsia, Sherrie
Television
Basic receiver with additional function
Multimode
348913, H04N 546
Patent
active
057196362
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a video display system capable of selectively displaying video signals of a plurality of types with different aspect ratios on a screen and, more particularly, to an improvement of a letter-box screen detection apparatus for determining whether a video signal to be displayed on the screen is a letter-box screen.
BACKGROUND ART
As is well known, for the NTSC (National Television System Committee) system which is one of conventional television broadcasting systems, the aspect ratio of a video signal is defined as 4:3. On the other hand, high-definition (high-vision) television systems have been developed recently. As leading high-definition television systems, there are the MUSE (Multiple Sub-Nyquist Sampling Encoding) system, the EDTV (Extended Definition Television) system as an improved NTSC system, and the like.
In such a high-definition television system, the aspect ratio of a video signal is being settled at 16:9. For this reason, even in a field of television sets for displaying a video signal, apparatuses called wide TVs (Television) capable of displaying a wide screen are rapidly spreading recently.
Many packaged software such as video tapes and laser disks which record video signals with aspect ratios wider than 4:3, such as movie sizes, are commercially available. Video software of this type often has a display form called a letter-box screen as shown in FIG. 1, in which black non-image portions P1 and P2 without any video are inserted above and below a main screen S in display on a screen with an aspect ratio of 4:3.
The video software having a wide screen are expected to increase in the future. In this case, video signals having various aspect ratios of 4:3, 16:9, or a movie size are present, and this poses a problem. In fact, there are letter-box screens of various types, i.e., videos having various aspect ratios and various display forms.
For example, FIGS. 2A and 2B show two types of movie software having an aspect ratio of 1.85:1, i.e., a so-called vista size but different subtitle positions. FIGS. 2C and 2D show two types of movie software having an aspect ratio of 2.35:1, i.e., a so-called cinemascope size but different subtitle positions. In addition, the display form variously changes in accordance with the number of subtitle lines, or domestic or foreign movie software. Dubbed software need no subtitle, and its display form changes accordingly. For example, the number of lines of an upper-side non-image portion varies from about 10 to 50.
In a conventional wide TV, various display means have been examined to cope with the above-mentioned various wide video software. For example, FIG. 3A shows a mode (normal mode) in which non-image portions are formed on the left and right sides of a video. FIG. 3B shows a mode (zoom mode) in which a video image is extended in the vertical and horizontal directions to display the horizontal video region on the display screen to its horizontal limit while cutting the upper and lower portions of the video. FIG. 3C shows a mode (live mode) in which the horizontal video region of a video is displayed on the display screen to its horizontal limit while the vertical video region is extended at a certain ratio. FIG. 3D shows a mode (full mode) in which a video is extended only in the horizontal direction, thereby displaying the video region on the display screen to its horizontal limit.
When a letter-box screen video signal is to be displayed on a wide TV, the video signal is displayed in any one of the above four modes. In the normal mode, however, a region where the video is actually displayed is small, so advantages in large screen display decrease. In the zoom mode, the upper and lower portions of the video with an aspect ratio of 4:3 is cut. However, since these cut portions have no picture pattern from the first, no problem is particularly posed. In the zoom mode, the picture pattern portion is rather conveniently displayed on the screen to its limit.
However, in, e.g., movie software, when a video sig
REFERENCES:
patent: 5309234 (1994-05-01), Kranawetter
patent: 5486871 (1996-01-01), Filliman
Fujishima Tsutomu
Ishii Satoyuki
Kamimura Shigeki
Hsia Sherrie
Kabushiki Kaisha Toshiba
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