Abstract: A control system for a bidirectional printer having a print head carriage movable at different speeds on different printing lines employs a microcomputer which generates a desired velocity profile for the carriage motion. This desired velocity profile is continuously compared with the actual velocity and the error voltage generated is used to control pulse width modulator circuitry which supplies driving power to carriage drive motor.

Abstract: A control system for a bidirectional printer having a print head carriage movable at different speeds on different printing lines provides for equal stopping distance in the margin at both high and low speed operation. This is accomplished by delaying the initiation of stopping carriage motion when printing at low speed so that the carriage travels farther into the margin and this distance is controlled so as to be equal to the travel distance at the end of a line printed at high speed.

Abstract: A real time tachometer is realized in an electromechanical device having a moving member, for example a disk, of nonmagnetic electrically conductive material driven by a suitable moving device, for example a rotating shaft, the velocity of which is to be determined. An assembly of at least one permanent magnet and at least one Hall effect device is arranged for inducing eddy currents in the moving member or rotating disk and measuring them for indicating the relative velocity. The placement and electric interconnection of the Hall effect devices measure the magnetic field provided by the magnet and in an alternate embodiment incorporate compensation for runout and adverse deflection with a rotating disk.