Video display apparatus for pictures with different aspect ratios

• US 5,193,006 A
• Filed: 01/26/1989
• Issued: 03/09/1993
• Est. Priority Date: 01/29/1988
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamazaki, Eiichi
• Primary Examiner(s): Chin, Tommy P.
• Application Number:
  US07/301,461
• Time in Patent Office: 1,503 Days
• Field of Search: 358/242, 358/141, 358/230, 358/142
• US Class Current: 348/173
• CPC Class Codes: H04N 11/24 High-definition television systems
• CPC Class Codes: H04N 7/0122 the input and the output signals having different aspect ratios

Abstract

When a picture display section (or screen) for high-quality TV system (HDTV system) is used for displaying pictures of ordinary TV system with an aspect ratio different from that of the high-quality TV picture, the blank portions on the screen where no picture is illuminated to display at a brightness level almost equal to a picture mean luminance so that there will be no local variations in the luminace on the screen due to deterioration of fluorescent materials on the screen. For this purpose, the picture display portion is moved over the screen; or the video signals are attenuated toward the ends of the picture display portion. As a result, the variations in luminance on the screen become small and unnoticeable.

Claims

1. A video display apparatus for displaying pictures with different aspect ratios, comprising:

means for receiving a first video signal and a second video signal, the first and second video signals having different aspect ratios;

a picture display section for displaying a picture produced by one of the first and second video signals on a screen having fluorescent materials thereon; and

means for illuminating blank portions on the screen where no picture is displayed at a brightness level substantially equal to a picture mean luminance of a picture display portion when the second video signal is displayed on the display section, the blank portions being produced because of the difference in aspect ratio between the first and second video signals;

wherein the illuminating means includes means for continuously detecting a high-voltage mean current for driving the screen, and means responsive to the detecting means for obtaining a respective mean value of the continuously detected high-voltage mean current and for illuminating the blank portions at the brightness level substantially equal to the picture mean luminance in accordance with the mean value when the second video signal is displayed on the display section, the first video signal being a high-quality TV signal and the second video signal being a standard TV signal.

2. A video display apparatus according to claim 1, wherein the illuminating means includes means for displaying information in the blank portions.