Calcomp Inc.

August D Coby

Sandor L Lengyel

Liang Shih

Richard A Hahs

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.

Sensor system for printers

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. When pre-calibrating, there is a look-up table containing a plurality of pre-established gains associated with respective ones of a plurality of target positions and the compensation logic selects a gain from the look-up table employs the gain to move the member directly to the desired final position.

Automatic calibration and servo control scheme for offsetting mechanical

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. The method comprises the steps of, sensing the position of the DC precision positioner and outputting a digital signal indicating the position; calculating the slope of the voltage output from the DC driver; obtaining a pre-established voltage compensation value on a compensation voltage curve which will force the voltage output from the DC driver to attain a value on a voltage curve having a constant slope and no deadband; and, inputting the pre-established voltage compensation value to the DC driver in combination with the non-regulated voltage input whereby the voltage output from the DC driver driving the DC precision positioner attains the value on the voltage curve having a constant slope and no deadband.

Method and apparatus for employing an unregulated power supply to power

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. At the time of plotting with the vector plotter, the method comprises adjusting the current applied to the drive motors by the plotter logic as a function of the proper friction compensation factor in the memory for the motor moved and the direction of motor movement.

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Brea, CA, United States of America

August D Coby