Video measuring system for defining location orthogonally

Apparatus for determining the location of a hole in a circuit panel comprising:

• imaging means for generating a plurality of scan signals having magnitudes representative of features of the hole in the circuit panel;
• means for generating pulses at a fixed frequency;
• first accumulator means for accumulating said pulses during a first portion of each of the scan signals representative of a distance from a reference position to a boundary point of the hole;
• second accumulator means for accumulating said pulses during a second portion of each of the scan signals representative of a distance across the hole;
• means responsive to the magnitudes of the scan signals for gating said pulses to the appropriate one of the first or second accumulator means;
• means for comparing each value accumulated by the second accumulator means to a preset minimum value and for discarding values accumulated by the first and the second accumulator means if the value accumulated by the second accumulator means is less than the preset minimum value;
• and
• processor means for first selecting certain values accumulated by the first and the second accumulator means based on the expected size of the hole, to provide a representative sample of the features in the approximate center of the hole represented by the magnitudes of the scan signals, and for then processing only said selected values to determine the location of the hole in the circuit panel.