Winding – tensioning – or guiding – Strand tensioning device – Tortuous course
Patent
1980-09-10
1982-10-05
Christian, Leonard D.
Winding, tensioning, or guiding
Strand tensioning device
Tortuous course
242191, G03B 104, G11B 1532, B65H 5938
Patent
active
043524729
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to cassette tape recorders and more particularly to a system for detection of the playtime type of standard tape cassettes in tape recorders or players of the type having means for detecting the angular velocity of at least one of the reels for enabling automatic control or display functions to be effected, at least partly based on the detection result as to the playtime type, i.e. the tape thickness, of the cassette.
Advanced tape recorders as disclosed e.g. in U.S. Pat. No. 3,834,648 and DE-OS No. 26 50 665 comprise detector and calculator means operable to steadily register the movements of the tape, during playing, recording or fast winding, and effect a digital displaying of the tape position based on a true playing time basis. Several functions such as automatic fast forward winding or rewinding to a desired tape position are hereby obtainable in an easy manner.
The tape position, of course, is correlated with the degree of tape filling of either of the two reels, i.e. with the reel radius of each one of the reels. This radius can be measured rather accurately by detecting, e.g. by a tachometer, the angular velocity of the reel and another velocity, viz. either (1) the speed with which the tape is reeled on or off or (2) the angular velocity of the opposite reel. It can be demonstrated, as already well known, that at least the relative tape position can be automatically calculated from such two simultaneous detection results, when the thickness of the tape is known.
In these advanced tape recorders, therefore, it is sufficient to read into the control device the necessary information as to the thickness of the tape to be used, whereafter the various control or display functions relating to the tape position can be effected automatically. A simple way, of course is to arrange for a manually operable selector which can be preset in accordance with the cassette type to be used; according to normal standards the audio cassettes are marked with a maximum playing time of e.g. 60, 90 or 120 minutes, corresponding to respective thicknesses and lengths of the tape for enabling each "side" of the cassette to show a playing time of 30, 45 and 60 minutes, respectively. It is even known to provide for automatic selection by preparing the cassettes with relevant indicator means and the tape recorder with means for sensing the indicator means of the cassettes, whereby the user need not care about the tape thickness information.
However, it seems difficult for the manufacturers of cassettes and recorders, respectively, to agree on some universal standards in this respect, and, besides, it even seems difficult for the manufacturers of cassettes to fully standardize the cassettes with respect to tape length and thickness and playtime marking. Thus, a cassette of the "90 min" type may contain a shortened length of thin tape as adapted for use in a standard "120 min" cassette, and a playtime marking may show "60+15 min" without an indication as to the actual thickness of the tape used.
It is the purpose of this invention to provide a tape recorder of the type referred to, which is provided with means for determining the thickness of the tape to be used without relying on manual selection or on automatic selection based on indicator means on the cassettes.
According to the invention the recorder (and/or player) comprises control means for actuating said angular velocity detecting means of a reel during a first short interval of time and thereafter again during a second short interval of time timely spaced from the first interval, means for memorizing at least the first detection result, and calculator means for calculating the tape thickness based on the two detection results and the linear velocity of the tape or corresponding detection results referring to the other reel.
In connection with the invention it is recognized that while as well known it is possible to detect by way of the reel rotation the tape displacement between two spaced measuring instances or short measuring intervals, wh
REFERENCES:
patent: 3834648 (1974-09-01), Rose et al.
patent: 4172231 (1979-10-01), d'Alayer de Costemore d'Arc
patent: 4280159 (1981-07-01), Nakayama
Bang and Olufsen A/S
Christian Leonard D.
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