Pen plotter pen type identification system

Abstract

A pen type sensor for use in a graphics pen plotter wherein plotter pens are moved along a pre-established path between a pen holding area and a plotting area for reading a plurality of vertically oriented reflective indicia positions thereon to create a binary logic output signal representative of the pen type. There is a hollow body member having a pair of angled front surfaces. Light emitting apparatus is associated with one of the pair of angled front surfaces for directing a light beam to simultaneously strike the indicia positions at a point on the path of pen movement. A plurality of light detectors are associated with the other of the pair of angled front surfaces for receiving on respective sensing surfaces thereof the light beam as it is reflected by reflective indicia on a pen at respective ones of the positions and for creating respective bi-stable output signals reflecting the presence and absense of reflected light on the sensing surfaces. Finally, there is apparatus for reading the output signals from the detector means as the binary logic output signal as pens pass the point on the path.