Typewriter Escapement Mechanism
Original Publication Date: 1979-Jun-01
Included in the Prior Art Database: 2005-Feb-20
The escapement mechanism shown in Fig. 1 was disclosed in U.S. Patent 4,101,224. In this escapement mechanism, a leadscrew 10 for driving a carrier and printhead along the length of a platen supports ratchet wheel 12. The escapement of leadscrew 10 is controlled by ratchet 12. A keyboard depression causes print shaft 14 and cam 16 to rotate one complete cycle. Cam follower 18 follows the contour of cam 16 and rotates links 20 clockwise when a high area on cam 16 is encountered. The clockwise rotation of links 20 causes bracket 22 to rotate detent arm 24 and pawl knock-off arm 26 in a clockwise direction. As a result of this clockwise motion, pawl knock-off arm 26 engages pawl or armature 28 and rotates it out of engagement with ratchet 12, and detent arm 24 detents ratchet wheel 12 to inhibit escapement.