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:
Feb. 02, 1999
Filed:
Oct. 10, 1995
Franz Kuchar, Vinna, AT;
U.S.Philips Corporation, New York, NY (US);
Abstract
A method of and a device for determining the total playing time of a magnetic tape accommodated in a cassette (1) in a magnetic-tape recording and/or reproducing apparatus, for example, a video recorder of the helical-scan type. The tape (4) is moved between a tape spool coupled to a first reel disc (2) and a tape spool coupled to a second reel disc (3), two measurements being carried out. In the first measurement, the tape is moved with a known tape speed. The revolution times (T.sub.l, T.sub.r) of the first and the second reel disc are measured in this first measurement and a parameter is derived which corresponds to the sum of the squares of the revolution times. A cassette-specific constant (.beta.) is derived from this parameter and the known tape speed. In a second measurement, the revolution times of the first and the second reel disc are measured during N revolutions of one of the two reel discs for each revolution of this reel disc. For each revolution, a ratio K(n) is calculated from the revolution times thus determined and the cassette-specific constant, K(n) being proportional to L(n)/L.sub.t and L.sub.t being the total length of the tape and L(n) being either the length already used or the residual length of the tape, where n is an integer and 1.ltoreq.n.ltoreq.N. In an approximation, the N calculated ratios K(n) are approximated by an at least quadratic function in dependence on n and the total playing time is determined from a constant A in the function (K(n)=X+A.multidot.n+B.multidot.n.sup.2 + . . . ) thus obtained.