Chordal tolerance control in circles on pen plotters for increased throughput

In a pen plotter including circle plotting logic which determines a length and number of chords to employ in plotting circles wherein said determined length of the chord is not necessarily the longest possible which would still be separately indiscernible by a naked eye from adjacent chords in the circle and from a theoretical circular arc which said chord represents, the improvement to maximize throughput of the plotter in plotting circles comprising:

• a) a look-up table which electronically stores for a particular circle radius a maximum length of a chord which is separately indiscernible by the naked eye from adjacent chords in the circle and from a theoretical circular arc which said chord represents;
• and,
• b) logic within the circle plotting logic for comparing said determined length of a chord to be employed in plotting a circle having a particular radius to said maximum length chord associated with said radius of the circular arc obtained from the look-up table, and for substituting said maximum length chord and determining an associated number of said maximum length chords to be employed to plot the circle if said determined length of the chord is shorter than said maximum length chord.

In the plotting of circles with a pen plotter, the method of chord length and number determination to maximize throughput of the plotter when plotting circles having a radius equal to or smaller than a small radius lower limit wherein an independently calculated chord length for a circle of the small radius lower limit is less than a maximum chord length, said maximum chord length being obtainable from a look-up table resident in the pen plotter which electronically stores for a particular circle radius equal to or smaller than a small radius lower limit, a maximum chord length which is separately indiscernible to a naked eye in a circle of that radius, comprising the steps of:

• a) employing the 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,
• b) employing the maximum chord length obtained from the look-up table which is associated with the radius of a circle being plotted when said circle has a radius equal to or smaller than the small radius lower limit, and determining an associated number of said maximum chord lengths to be employed to plot the circle.

A method of plotting circles with a pen plotter to maximize throughput of the plotter when plotting circles having a radius equal to or smaller than a small radius lower limit comprising the steps of:

• a) 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,
• b) employing a maximum chord length obtained from a look-up table resident in the pen plotter, wherein said look-up table electronically stores for a particular circle radius equal to or smaller than a small radius lower limit a maximum chord length which is separately indiscernible to a naked eye in a circle of that radius when plotting a circle having a radius equal to or smaller than the small radius lower limit and determining an associated number of said maximum chord lengths to be employed to plot the circle.