An indicating device includes a drive member and a driven member. The driven member is non-rotatably immobilized by the successive engagement of a convex surface on the drive member with a plurality of concave surfaces on the driven member. The driven member further includes a plurality of protrusions...http://www.google.com.tw/patents/US8082873?utm_source=gb-gplus-share專利 US8082873 - Drive mechanism for an indicating device
