| 摘要 |
PURPOSE:To eliminate an effect of the accuracy of tooth profile and to prevent the accuracy of positioning from deteriorating due to wear of teeth by making the number of teeth of a pinion more than half as many as the number of steps of a step motor and making also the pitch of teeth of a rack more than twice as much as a track pitch. CONSTITUTION:By making the number of teeth of the pinion 13 half the number of steps of the step motor 11 and also the pitch of teeth of the rack 18 double the track pitch, a contact part between the rack 18 and pinion 13 is equalized on right and left relatively to their respective teeth each other. Consequently, at the time of positioning a head to a track position, the meshing position of the rack 18 with the pinion 13 in their respective teeth profiles is in their same positional relations with regard to any tracks, so that even if the accuracy of tooth profile on the pinion 13 and rack 18 is not so good, and on the other hand even if their teeth are worn out, it is not necessary to reposition in various points in the middle of their intermesh. In this way, the accuracy of positioning the head will never deteriorate provided that the pitch is insured in accuracy.
|
