| 摘要 |
A tape recorder of the type which comprises indicator means for the progress of the tape on a true playing time basis, also during fast winding, makes use of a system for measuring the speed of rotation of at least one of the tape reels, whereby the speed or a counted number of revolutions will be indicative of the tape position when the thickness of the tape is known. According to the invention the thickness is measured automatically by means of the same system, based on timely spaced measurements of the speed of rotation and knowledge about the length of tape having been reeled in the meantime. This length may be measured in a direct manner, but it is preferred to calculate it automatically based on the lapse of time and the known standard playing speed. The recorder comprises the necessary processor equipment for automatically calculating the tape thickness on this basis and reading the resulting measuring result as a tape type selector signal into the main control unit of the recorder. |
