Abstract: This is a method and associated implementation logic for plotting circles with a pen plotter to obtain a substantial and unexpected increase in throughput of the plotter when plotting circles having a radius equal to or smaller than a small radius lower limit. The method comprises the steps of, employing an independently calculated chord length and number of chords at the independently calculated chord length for plotting circles having a radius greater than the small radius lower limit; and, employing a maximum chord length which is not separately discernable to the naked eye in a circle of a desired radius and an associated number of maximum length chords when plotting a circle having a radius equal to or smaller than the small radius lower limit. In tested embodiments, the method has provided a twelve-fold increase in plotter throughput when plotting small radius circles.

Abstract: Apparatus for automatically determining if roll or cut-sheet media is being used in a plotter or similar device and for automatically setting some of the operating parameters in lieu of manual input by an operator. The roll media has a hole therein adjacent the roll end. An optical sensing pair senses the passage of light through the media at a point passed by the hole. If a suspected end is found, the media is moved a distance greater than the hole diameter. If light is still detected, the edge of a cut sheet has been detected. If light is no longer detected, it was a hole and the end of a roll of media has been detected. By being able to determine the type of media involved, the plotter logic can measure the width of the media and then get a desired length from a look-up table and thereafter determine if there is a proper length of media available for the plot.

Abstract: In a pen plotter having a plotting head carrying one half of a pen exchanging mechanism including a holding plate pivotally attached to a plotting head for pivotal movement to raise and lower a pen gripped therein and carried thereby a spring-biased gripping finger pivotally carried by the holding plate for releasably holding a pen, this is a dual-function sensing apparatus for providing a single output signal indicating pen presence and pen up/down position. There is an optical sensor comprising a light source and a light detector separated from the light source by a space and having a sensing surface upon which a beam of light impinges and wherein the level of signal output is a function of the amount of light impinging on the sensing surface.

Abstract: This invention is directed to the use of single optical sensor to replace two mechanical sensors in a pen plotter. A light beam is directed through a slot in the plotter's main platen. The light beam is detected to provide a signal output. Servo fan motors of the plotter are turned on when the light beam is broken by media placed into the plotter for plotting as one function. A load sequence of the plotter is started only after a start command is input by a user through a control console and the light beam is broken by media placed into the plotter for plotting as a second function.

Abstract: This invention is directed to simplified menu display and inputting apparatus for use in a pen plotter having a set of up, down, left, and right control buttons used for pen control. There is an alpha-numeric display for displaying menu choices, an ON LINE button for placing the plotter in an on line mode of operation wherein the pen control buttons are employed in their normal manner, and a MENU button for placing the plotter in a menu input mode wherein the pen control buttons are employed to move from top to bottom through top level menu definitions and from left to right through subfunction menu definitions. Displayed menu choices are selected for insertion into a current parameter value list while in the menu input mode. Provision is made to identify a number of users and store their operating parameters separately and individually so that users can return and use the plotter with their values without having to re-enter them each time.