| 摘要 |
The running length of magnetic tape being fed from a supply reel to a takeup reel on a tape recorder is metered by first reducing the variable revolving speed of the takeup reel in a predetermined ratio, adding the reduced revolving speed of the takeup reel to the variable revolving speed of the supply reel, and converting the resultantly obtained sum into a desired unit of indication. This metering method finds application in several devices also disclosed herein, in which are commonly employed planet differential means in association with both of a pair of revolvable shafts on which are respectively mounted the supply and takeup reels. The planet differential means include a pair of planet gears whose revolution around a common axis, corresponding to the aforementioned sum, is conveyed to a digital tape footage counter or other indicating means. |
