Abstract: Disclosed herein is an arm deflecting drive system for strip chart recorders. The drive system mechanism includes a variable resistance structure which produces a position signal indicative of the angular position of the deflecting arm, which signal is proportional to the tangent of the position angle of the arm. The drive mechanism further includes a differential amplifier receiving both the position signal and a reference signal and generating a deflection signal related to the difference between the reference and position signals. In accordance with the invention, the variable resistance structure may include a track of electrically resistant material contoured to provide the tangential relationship between the position signal and the position angle or, alternatively, the track may be formed from an inhomogeneous material to provide such tangential relationship.

Abstract: For improving the class of measuring quality of ink jet recorders the invention provides for a rigid connection of the permanent magnet of the electromagnetic driving system with the securing point of the capillary tube within the ink supply system by means of a torsion-resistant coupling element. It is suggested to place the securing point of said coupling element with said capillary tube as close as possible adjacent to the exit nozzle so that deviations of deflection of the exit nozzle by tumbling motions of the nozzle are prevented. The torsion-resistant coupling element transmits the instantaneous value of the exit nozzle deflection from the securing point to the measuring value detector of the control system of the ink jet recorder. Preferably, the coupling element is a length of a glass tube supported for rotation about its axis by two bearings placed upstream and downstream of the permanent magnet.