Abstract: A method and apparatus for precisely advancing film material between two rollers includes a driven roller having a medium hardness rubber surface and a non-driven hard surfaced roller which contacts precision surfaces at either end of the driven roller to accurately control the spacing between the two rollers. The non-driven roller is urged against the driven roller precision surfaces by a spring force, and causes the rubber of the driven roller to compress when film material is in an operative position between the roller pair.

Abstract: A method and apparatus for maintaining a controlled precise energy output level for a laser diode, particularly useful in a precision scanning environment, provide for a thermal stabilization current to be added to the normal bias exposure current of the diode The thermal stabilization current is modeled to account for the temperature variation of the laser diode junction which affects the light energy output as a function of current. The addition of the thermal stabilization current provides a substantially flat and constant, precise output energy from the laser diode during its "on" time as a function of an input exposure value.

Abstract: A method and apparatus for accurately controlling a hysteresis synchronous motor velocity eliminate low frequency hunting, which is characteristic of the motor. A nominal input phase current is modified by providing feedback information, thereby enabling a microprocessor control system to modify the phase of quadrature input current signal to the motor and thereby eliminating hunting of the motor. Accordingly, in a high resolution scanning application, speed variations which could cause disturbing artifacts to appear in an output image are eliminated.