Device for determining the total playing of a tape
US5867354A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 10, 1995 |
| Grant date | Feb 2, 1999 |
| Priority date | — |
| Expiry date | Oct 10, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B27/13
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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 lengt…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.