US 4,021,605 AGranted

Electronic circuit for electronic stencil cutter

AssigneeA. B. Dick Company

InventorJulio G. Tauszig

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Abstract

Stencil cutting apparatus for electrically burning information from an original document into a stencil material having non-linear burning characteristics by the application of electrical pulses to a stylus contacting the stencil material positioned on a rotatable cylinder, includes a photomultiplier for scanning the original document and providing an output signal the amplitude of which is proportional to the light reflected by the information thereon, a circuit including a square wave oscillator and wave shaping network which alters the square wave in relation to the burning characteristics of the stencil material to produce a resultant train of pulses and a comparator circuit which adds the photomultiplier signal and train of pulses. The comparator provides output pulses having a width determined by the addition of the last-mentioned signal and pulses which are fed to the stylus for burning the stencil. The cylinder upon which the stencil material is mounted includes a magnet which revolves as the cylinder rotates. The movement of the magnet past a sensing coil produces a signal to discontinue the burning as the stylus passes over the stencil clamp of the cylinder.

Claims10

Dependent claims

Apparatus for electrically burning information from an original document into a stencil material having non-linear burning characteristics including a stylus for applying electrical pulses for burning said material and an electrical circuit coupled to said stylus for providing said electrical pulses thereto, said circuit comprising:

optical sensor means for scanning the information on said original document and providing an output signal, the amplitude of which is proportional to the shade of said information being scanned, circuit means for providing a train of pulses having a predetermined shape which is selected to conform to the non-linear characteristics of the stencil material, said circuit means comprising wave signal generating means and circuitry coupled thereto for shaping the output signal of said generating means to provide a train of non-linearly varying wave pulses and means coupled to said optical sensor means, said circuit means and said stylus means for comparing the output signal provided by said sensor means and the pulses provided by said circuit means, said comparing means providing output pulses having widths representing the intervals of time when the amplitude of the output signal of said optical sensor means is greater than the amplitude of the non-linearly varying wave pulses for application to said stylus for use in burning said stencil material, the width of said output pulses increasing non-linearly as the shade of the information scanned by said optical sensor means becomes darker.

Dependencies are inferred from the claim text.