| 摘要 |
<p>Apparatus is provided for indicating the amount of tape wound upon a reel, such as a supply reel or a rake-up reel, in a two-reel cartridge when the cartridge is loaded into a processing device of the type which includes a loading device for withdrawing from the cartridge a portion of the tape wound upon the reel. A signal is generated representing the angular velocity of the reel when that reel rotates in response to the withdrawal of tape from the cartridge. This generated signal is combined with predetermined signals representing predetermined characteristics of the tape, the combined signals then being used to indicate the amount of tape which is wound upon the reel. In a preferred embodiment, the predetermined signals are: v, the velocity of the tape as it is unwound from the reel; ?, the thickness of the tape; RH, the diameter of the innermost winding of the tape upon the reel; and the signal which represents the angular velocity of the tape is ps. A micro-processor having an arithmetic section combines, or operates upon these signals in accordance with the expression , wherein TS is the amount of tape wound upon the reel in terms of time. A particular application of this apparatus is in a video tape recorder having a guide drum about which the withdrawn portion of tape is deployed during the loading thereof, the amount of tape remaining in the cartridge for recording or playback being indicated by this apparatus. -i-</p> |
