| 摘要 |
PURPOSE:To secure the accurate positioning of a head by using a rotary member which decides one revolution of a head feed motor that is equal to a prescribed step-advancing shift amount of the head and a means which locks the rotary member every revolution. CONSTITUTION:The trigger pulse for step feed of a head 3 is applied to an input terminal 58. In this case, a current is supplied to a motor 9 by the polarity decided by a switch 51. A click gear 12 of a rotary shaft 13 is revolved with the drive of the motor 9. A click arm 15 is revolved as shown by an alternate long and short dush line to turn on a switch 18. Thus a transistor (TR) 53 is kept on and at the same time the motor 9 keeps its revolutions. Then an engaging pin 12a engages again with a notched part 15b with a revolution of the gear 12. At the same time, the switch 18 is turned off. Thus the current of the motor 9 is cut off by the TR53, and both ends of a TR54 are shorted. The head 3 is fed accurately since a revolution of the gear 12 is equal to a track pitch shift of a head carriage 5. |
