Document counter and endorser with light source control
AssigneeBrandt, Inc.
InventorRichard A. Melcher
Life of this patent
Estimating the term…
Abstract
Apparatus for examining documents moved along a path between a light source normally energized at a first level and a photodetector, in which a first potential proportional to the long term average value of the photodetector output with no document between the light source and the photodetector and a second potential proportional to the instantaneous value of the photodetector output are compared to energize the light source at a higher level by shorting part of the resistance in the normal energizing circuit when the second potential falls below a predetermined percentage of the first potential.
Claims4
Apparatus for examining documents including in combination, a light source, a photodetector, means mounting said photodetector and said light source in spaced relationship with light from said source directed toward said photoconductor, means for moving documents along a path between said light source and said photodetector, means normally energizing said source at a first level, means responsive to said photodetector for storing a first potential proportional to the long term average value of the photodetector output when no document is present, means for comparing said first potential with a second potential proportional to the instantaneous value of said photodetector output for producing a control signal when said second potential is less than said first potential, and means responsive to said control signal for energizing said source at a second level higher than said first level.
Dependencies are inferred from the claim text.