Abstract: An improved sensor system for a printer having a print carriage comprising an ink source, a print head, and a coupler for coupling the ink source to the print head, the coupler including a tube for carrying the ink and sensors for detecting voids in the ink carried by the tubes and positioned in close proximity to the ink source and the print head. A controller is coupled to the sensors and responsive to signals therefrom to stop the print carriage when voids are simultaneously detected by the sensors.

Abstract: In a mechanical device in which a member is moved by an electrical actuator through an electronic and mechanical linkage, apparatus for compensating for changes in system gain to allow precision movement with non-precision components. There a sensor for accurately determining positions of the member, control logic connected to provide a control signal to the actuator, and an adjustable gain control for adjusting the gain of the control signal. Compensation logic is connected to receive positional signals from the sensor, for applying a control signal to the actuator to move the member to a target position closest to a desired final position, for adjusting the gain of the control signal with the adjustable gain control until the member is located at the target position within acceptable tolerance limits, and for then employing that gain to move the member to the desired final position. The method associated with the apparatus can be done in real-time or by pre-calibrating in advance.

Abstract: This is a method and associated apparatus for employing a non-regulated voltage input to a DC driver normally outputting a voltage having a curve with a dead band and a variable slope which is a function of the non-regulated voltage input to produce an output to a DC precision positioner from the DC driver which has a constant slope and no deadband. It is particularly useful in pen plotters.

Abstract: A method and associated apparatus for frictionally compensating a vector plotter having an X-drive motor for driving plotting apparatus in +X and -X directions and a Y-drive motor for driving plotting apparatus in +Y and -Y directions and logic for applying positive and negative electrical drive currents to the respective motors to affect plotting. Plotter accuracy and associated plot quality are improved by the method which comprises the steps of, providing a memory for holding +X, -X, +Y, and -Y friction compensation factors; prior to the time of plotting with the vector plotter, calibrating the plotter by (1) causing the motors to move the plotting apparatus in +X, -X, +Y, and -Y directions, (2) measuring the friction during the +X, -X, +Y, and -Y directional movement, and (3) calculating and storing the +X, -X, +Y, and -Y friction compensation factors in the memory.

Abstract: A system for measuring the resistance of an earth electrode such as a coal mine safety ground bed. Current is circulated between the bed and an auxiliary current probe installed approximately ten times the maximum linear dimension of the ground bed under test. By measuring the voltage level between the ground bed and an auxiliary voltage probe placed about 62 percent of the distance from the ground bed to the auxiliary current electrode along the straight line between them, the true resistance of the ground bed can be determined. To sense the current value of the current flowing into the ground bed, a current transformer is placed around the lead to the ground bed. Voltage measurements are made with a high impedance voltage amplifier connected between the ground bed and the auxiliary voltage probe. Continuous monitoring of the measurements obtained without the presence of operator is achieved by using an analog divider and filter with their output terminal being connected to a recorder.