| 摘要 |
<p>PURPOSE:To detect economically the absolute position of a tension arm by using an initial position setting means which cancels the clearing state of an up/down counter and a means which reads the contents of the up/down counter. CONSTITUTION:A microcomputer 31 clears the contents of up/down counters 29 and 30 if they are under initial resetting when a power supply is applied. Then a roll-out reel motor 2 and a take-up reel motor 19 are revolved in the negative and positive directions when it is decided that the 1-revolution signals of incremental rotary encoders 25 and 26 are turned off. Then the clear states of the counters 29 and 30 are cancelled. Thus the counters 29 and 30 perform the up/ down counts in response to the shifts of tension arms 5 and 16. These count values show the absolute positions of arms 5 and 16 respectively. Therefore the position of the tension arm is obtained by reading the count values of counters 29 and 30 by the computer 31.</p> |
