Abstract: A viscosity controller automatically monitoring and controlling the viscosity of ink in a pad printing device on a continuous basis throughout the printing process includes a sealed ink cup having mounted thereon a motor with a paddle extending into the ink cup, a solvent tank in flow communication with the ink cup, and a valve for allowing selective amounts of the solvent to be added to the ink cup from the solvent tank. The viscosity of the ink in the cup creates torque on the paddle that affects the number of encoder pulses that are counted per time period by a motor encoder mounted to the motor, and the encoder pulses are counted and compared to a look up table stored in the microprocessor of the controller to determine if the valve should be opened to add diluting agent to the ink cup so that the ink viscosity can be maintained at a preset or predetermined value.

Abstract: There is disclosed a constant amplitude controller with feedback control for a vibratory feeder apparatus wherein a controlled rectifier is used to rectify the A.C. line voltage applied to the feeder solenoid and to control the voltage to the feeder solenoid. Triggering of the controlled rectifier is accomplished by a bias control signal which is composed of an A.C. phase shift voltage superpositioned by a variable D.C. bias voltage. Mechanical coupling is provided between the solenoid and a transducer which provides feedback to control logic circuitry. In the control logic circuitry, the signal received from the transducer is compared with a signal received from an operator adjusted potentiometer. In this manner, the desired amplitude of the vibrator apparatus is compared with the actual amplitude of the vibrator apparatus and, if there is a discrepancy, the control logic circuitry modifies the amount of control voltage being transferred by the controlled rectifier.