| 摘要 |
A tape amount displaying apparatus displays a used amount of a tape or a remaining amount thereof. A signal corresponding to a length (lt) of an outermost periphery of the tape wound in a reel is outputted from an outermost periphery length signal outputting circuit and then stored in a memory. Each time a one-turn detecting circuit detects one turn of the reel, the predetermined value (2 pi d) is added to the length of the outermost periphery read out from the memory if a rotational direction detecting circuit detects that the reel rotates in a predetermined direction, or the predetermined value (2 pi d) is subtracted from the outermost periphery length if the rotational direction detecting circuit detects that the reel rotates in the opposite direction. The result of such an addition or subtraction is again stored in the memory. The content stored in the memory is squared (lt2), and then a predetermined value (4 pi 2rh2) is subtracted from the squared value (lt2) and, in addition, the result of the subtraction is divided by a predetermined value (4 pi d). As a result, a tape amount (Lt) is displayed in a display.
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