Abstract: A pen recorder is provided with a holder base and a hammer base which are movable along a platen. A plurality of pens are mounted in parallel on the holder base. A hammer for pressing any one of the pens is mounted on the hammer base. One of the bases is driven by a driving means such as a pulse motor. Moreover, a lock mechanism is provided for connecting the holder base and the hammer base. Thus, it becomes possible to select the pen to be pressed by the hammer through the movement of relative position between the bases effected by the lock mechanism.

Abstract: A pen recorder has two movable bases adapted to be movable in directions along a platen, one of the bases being driven in directions along the platen. A plurality of pens are mounted in parallel on one of the bases, and a hammer is mounted on the other base for pressing any one of the pens toward the platen. The base which is not driven has a lock lever adapted to engage with a plurality of portions of the base which is driven. The base which is not driven further has an urging lever for driving the lock lever. The urging lever is slidably mounted on a pen changeover shaft rotated by a driving mechanism. The pen recorder further has a spring for urging the lock lever in the locking direction, as well as forcing the urging lever to abut against the lock lever in the unlocking direction. Also disclosed is a method of setting the initial position of the pen recorder.