Magnetic signal detector
AssigneeDocutronix, Inc.
InventorsWilliam H. Krehl, John R. DeHart
Life of this patent
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Abstract
A circuit is disclosed for monitoring the output voltage of a magnetic pickup and for producing output signals representing the valid detection of bars of magnetized ink moved past the pickup. The circuit is capable of detecting and providing correct output data from input signals ranging from relatively weak signals of low amplitude to relatively strong signals which are of high amplitude and include overshoot pulses of substantial amplitude. The circuit is disclosed in association with a system for sorting envelopes containing inserts coded with bars of magnetic ink, the output of the signal detecting circuit being used as the input to a sorter logic controlling a sorter mechanism.
Claims10
A circuit for detecting signals from a voltage waveform generated by a pickup for sensing bars of magnetized material appearing on a carrier moved past the pickup and which voltage waveform for each bar moved past the pickup has a base voltage level and includes a first voltage pulse of one polarity relative to said base voltage followed by a second voltage pulse of opposite polarity relative to said base voltage, said circuit having said pickup voltage waveform as an input thereto and comprising a means for producing an output signal indicating the valid detection of a bar of magnetic material only when said voltage waveform undegoes a pulse of said one polarity having an amplitude greater than a first predetermined value and is immediately followed by a pulse of said opposite polarity having an amplitude greater than a second predetermined value.
A circuit for detecting signals from a voltage waveform generated by a pickup for sensing bars of magnetized material appearing on a carrier moved past the pickup and which voltage waveform for each bar moved past the pickup has a base voltage level and includes a first voltage pulse departing in one direction from said base voltage followed by a second voltage pulse departing in the opposite direction from said base voltage, said circuit comprising a first comparator for comparing a voltage waveform with a first predetermined set point voltage offset in said one direction from said base voltage and for producing a voltage signal B which persists for as long as the voltage of said waveform as measured in said one direction from said base voltage exceeds said first set point voltage, a second comparator for comparing said voltage waveform with a second predetermined set point voltage offset in said opposite direction from said base voltage and for producing a voltage signal C which persists for as long as the voltage of said waveform as measured in said opposite direction from said base voltage exceeds said second set point, a means for delaying said signal B to produce a delayed signal .DELTA.B of a duration substantially similar to that of said signal B but occurring later in time than said signal B, and an AND gate having as inputs said delayed signal .DELTA.B and said signal C and producing an output signal indicating the valid detection of a bar of magnetic material during the time said delayed signal .DELTA.B and said signal C exist simultaneously.
Dependencies are inferred from the claim text.