Process and device for the instantaneous display of a countryside scanned by a camera of the single line scanning type

• US 4,217,607 A
• Filed: 09/19/1978
• Issued: 08/12/1980
• Est. Priority Date: 05/07/1974
• Status: Expired due to Term

• Current Assignee: Societe Anonyme de Telecommunications (Safran SA)
• Original Assignee: Societe Anonyme de Telecommunications (Safran SA)
• Inventors: Cohen, Jean-Pierre D.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Coles, Edward L.
• Application Number:
  US05/943,867
• Time in Patent Office: 693 Days
• Field of Search: 358/109, 358/223, 354/65, 343/5 R, 343/5 PC, 343/112 A, 250/214 R, 250/236
• US Class Current: 348/145
• CPC Class Codes: H04N 7/005 using at least one opto-electrical conversion device

Abstract

A process for the instantaneous display of a countryside scanned by a camera apparatus of the single line scanning type, comprising charging the target of a double gun tube, acting as an intermediate information support between the single line scanning apparatus and a television receiver, by a first gun of the double gun tube along a writing line, in the effective rotation of the single line scanning device in the course of one period of the scanning video signal, said writing line moving over the target in accordance with a writing picture scanning the slope of which depends on the ratio V/H of the support of the camera apparatus, erasing the lines already written and stored so as to define on the target a moving rectangle which is not charged, in memory reading the space of the target which is charged in memory by a scanning effected by the second gun of the double gun tube at the television rate, the beginning and the end of the reading corresponding to two lines which move over the target in accordance with the reading picture scanning and are disposed respectively on each side of said moving rectangle, and sending the modulated current of the reading of the target, which constitutes the television video signal, to the television receiver.

Claims

1. A method for real time displaying on a TV monitor of a scene scanned from an aircraft by a line scan apparatus, wherein a two-gun tube is incorporated as an image storage means between the line scan apparatus and the TV monitor, said tube having a target, a writing gun connected to the output of the line scan apparatus and providing a writing beam for scanning said target to establish a charge pattern on the target, and a reading gun providing a reading beam for reading said charge pattern, comprising scanning the target by the writing gun line by line at a frame rate dependent on the speed-to-altitude ratio of the aircraft during the effective periods of the video signal from the line scan apparatus, erasing lines already written and stored so as to define on the target a moving rectangular area having no charge deposited thereon, said rectangular area comprising at least two line spaces, scanning that area of said target having charges thereon by the reading gun in accordance with the scanning standard of the TV monitor in such manner that the first and last lines read out by the reading gun during a frame scan are constantly situated on respective opposed sides of said moving rectangular area, and feeding the TV monitor with the signal from the reading gun.

2. A method as claimed in claim 1, wherein lines already written and stored are erased by the writing gun during the suppression periods of said video signal.

3. A method as claimed in claim 1, wherein lines already written and stored are erased by the reading gun by means of slight successive erasing motions during the picture fly back period of the reading gun.

4. A device for real time displaying on a TV monitor of a scene scanned from an aircraft by a line scan apparatus, comprising a two-gun tube incorporated as an image storage means between the line scan apparatus and the TV monitor, said tube having a target, a writing gun connected to the output of the line scan apparatus and providing a writing beam for scanning said target to establish a charge pattern on the target, and a reading gun connected to the TV monitor and providing a reading beam for reading said charge pattern, further comprising means for scanning the target by the writing gun line by line at a frame rate dependent on the speed-to-altitude ratio of the aircraft during the effective periods of the video signal from the line scan apparatus, means for erasing lines already written and stored so as to define on the target a moving rectangular area having no charge deposited thereon, said rectangular area comprising at least two line spaces, means for scanning that area of said target having charges thereon by the reading gun in accordance with the scanning standard of the TV monitor in such manner that the first and last lines read out by the reading gun during a frame scan are constantly situated on respective opposed sides of said moving rectangular area, and means for feeding the TV monitor with the signal from the reading gun.