Patent DE2139689A1 successfully refreshed from Google Patents.
US5101302A
Expired / Lapsed
US
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Apparatus for detecting marks on a magnetic tape which identify particular items of information recorded thereon
Assignee: US Philips Corp
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Filing: 1990-05-22
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Granted: 1992-03-31
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Expires: 2010-05-22
Abstract
Abstract The information signals recorded on a magnetic tape are accompanied by marks identifying particular items of such information, each mark (M 1 ) comprising at least one marking signal (S 1 ), the tape being driven by a tape-up reel hub (5) during recording. During playback a magnetic head (19) reproduces the recorded signals and a tachometer (46) coupled to the take-up reel hub (5) supplies a tacho-signal which is used by a microprocessor (42) as a reference for frequency comparison with the instantaneous frequency of the reproduced signals. When a predetermined relational condition exists between such frequencies the microprocessor (42) produces a signal indicating the presence of a mark (M 1 ). Since the frequency of the tacho-signal and the frequency of the reproduced signals from the tape are affected in the same way by variations in speed of the take-up reel hub, such variations do not affect accurate detection of the recording marks.
Inventors
- 👤 Gunter Schonthaler
- 👤 Hans Schranz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:53
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/02; G11B15/05; G11B15/087; G11B27/00; G11B27/10; G11B27/11; G11B27/13; G11B27/19; G11B27/28; G11B27/30; G11B27/3009; G11B27/3018; G11B27/34; G11B2220/00; G11B2220/90
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
224 words
Apparatus for detecting marks on a magnetic tape which identify recorded information signals thereon corresponding to particular items of information, each recording mark comprising at least one marking signal of a given frequency, the magnetic tape extending between a supply reel-hub and a take-up reel hub and being driven during recording by the take-up reel hub and being driven during recording by the take-up reel hub at a constant rotational speed, the supply and take-up reel hubs having respective drive mandrels, the apparatus including at least one magnetic head for reproducing the recorded signals on the magnetic tape; characterized in the said apparatus further comprises: frequency-comparison means coupled to said magnetic head for comparing the instantaneous frequency of the signals reproduced thereby with a reference frequency and for supplying a signal signifying the presence of a mark on the magnetic tape when a predetermined relational condition exists between said reference frequency and the frequency of the reproduced signals; and a tachometer coupled to the take-up reel mandrel for supplying to said frequency-comparison means a tacho-signal having a frequency proportional to the rotational speed of the take-up reel mandrel, the frequency of the tacho-signal constituting said reference frequency for said frequency-comparison means; whereby determination of whether said predetermined relational condition is satisfied is independent of variations in the rotational speed of the take-up reel mandrel.
Claim 2
Dependent Claim
224 words
Apparatus for detecting marks on a magnetic tape which identify recorded information signals thereon corresponding to particular items of information, each recording mark comprising at least one marking signal of a given frequency, the magnetic tape extending between a supply reel-hub and a take-up reel hub and being driven during recording by the take-up reel hub and being driven during recording by the take-up reel hub at a constant rotational speed, the supply and take-up reel hubs having respective drive mandrels, the apparatus including at least one magnetic head for reproducing the recorded signals on the magnetic tape; characterized in the said apparatus further comprises: frequency-comparison means coupled to said magnetic head for comparing the instantaneous frequency of the signals reproduced thereby with a reference frequency and for supplying a signal signifying the presence of a mark on the magnetic tape when a predetermined relational condition exists between said reference frequency and the frequency of the reproduced signals; and a tachometer coupled to the take-up reel mandrel for supplying to said frequency-comparison means a tacho-signal having a frequency proportional to the rotational speed of the take-up reel mandrel, the frequency of the tacho-signal constituting said reference frequency for said frequency-comparison means; whereby determination of whether said predetermined relational condition is satisfied is independent of variations in the rotational speed of the take-up reel mandrel.
Claim 3
Dependent Claim
86 words
Mark detection apparatus as claimed in claim 1, wherein said frequency-comparison means comprises a microprocessor which, for comparing the instantaneous frequency of the tacho-signal with the instantaneous frequency of the signals reproduced by the magnetic head, is adapted to determine the instantaneous period of the tacho-signal and the instantaneous period of the reproduced signals and to compare such determined periods in accordance with said predetermined relational condition, and if such condition is satisfied to produce a signal signifying the presence of a mark on the tape.
Claim 4
Dependent Claim
61 words
Recording apparatus as claimed in claim 2, wherein the microprocessor is adapted to formulate a tolerance window defining a lower limit and an upper limit of the period of the tacho-signal, and to determine whether the predetermined relational condition is satisfied by determining whether the detected instantaneous period of the signals reproduced by the magnetic head is within said tolerance window.
Claim 5
Dependent Claim
32 words
Recording apparatus as claimed in claim 3, wherein the microprocessor is adapted to supply a signal indicating the presence of a mark only if said predetermined relational condition has been satisfied recurrently.
Claim 6
Dependent Claim
32 words
Recording apparatus as claimed in claim 2, wherein the microprocessor is adapted to supply a signal indicating the presence of a mark only if said predetermined relational condition has been satisfied recurrently.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-31 | 1995-09-30 | 1996-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-31 | 1999-09-30 | 2000-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-31 | 2003-09-30 | 2004-03-31 | $7700.00 | Window Closed / Lapsed |