The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 23, 1976
Filed:
Jul. 24, 1974
Erich Langer, Vienna, OE;
U.S. Philips Corporation, New York, NY (US);
Abstract
In a recording and playback apparatus the tachometer of the servo system for controlling the speed of the drive shaft uses a disc with a closed magnetizable track, which cooperates with an even number of equidistantly spaced magnetic heads connected to a direct voltage source in the playback mode. Each head successively magnetizes the track in an opposite sense. One of the heads scans the magnetizations stored in the track for supplying the input signal for the servo system during a recording. When a new recording is made which is to follow an existing recording, the magnetic heads are disconnected from the direct voltage source, and switching from the playback to the recording mode is effected by means of a switching device which can be controlled by the pulses scanned from a synchronization track on the record carrier.