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US 4,665,820 AGranted
Print band timing mark detector
AssigneeCentronics Data Computer Corp.
InventorWalter C. Chapman
Life of this patent
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Abstract
In the print band timing system described herein, the bipolar pulse generated in a sensor by the passage of a print band timing mark is applied to a discriminating circuit which compares the pulse signal with a voltage level substantially equal to the nominal d.c. level of the sensor signal. Hystereis is provided in one direction only so that the nominal zero crossing is precisely determined in a time position relationship.
Claims7
A print band timing mark detector comprising:
- a sensing circuit including a sensor for providing a source signal, said source signal exhibiting a bipolar pulse responsive to the passing of a print band timing mark;
- low pass filter means for providing a d.c. reference voltage substantially equal to the nominal d.c. level of said source signal;
- amplifier means having inverting and non-inverting inputs and operative to generate an output which is a function of the difference of the inputs;
- means for applying said d.c. reference voltage to said inverting input;
- means for applying to said non-inverting input a first signal component which is a linear function of said source signal;
- means for applying to said non-inverting input a second signal component which is a non-linear function of the amplifier output
- whereby said amplifier responds to the passage of print band timing marks by generating a squarewave signal having one edge which is aligned with the nominal zero crossing of the bipolar pulse.
4 more elements
A print band timing mark detector comprising:
- a sensing circuit for providing a source signal, said sensing circuit including a sensor operative to generate in said source signal a bipolar pulse responsive to the passing of a print band timing mark;
- filter means including a capacitor for providing a d.c. reference voltage substantially equal to the nominal d.c. level of said source signal;
- amplifier means having inverting and non-inverting inputs and operative to generate an output which is a function of the difference of the inputs;
- means for applying said d.c. reference voltage to said inverting input;
- means for applying to said non-inverting input, through a first mixing resistance, a first signal component which is a linear function of said source signal;
- means for applying to said non-inverting input, through a second mixing resistance and a diode, a second signal component which is a non-linear function of the amplifier output
- whereby said amplifier responds to the passage of print band timing marks by generating a squarewave signal having one edge which is precisely aligned with the nominal zero crossing of the bipolar pulse generated by said sensing circuit.
4 more elements
A timing mark detector for print bands carrying raised timing marks comprising:
- a sensing circuit for providing a source signal, said sensing circuit including a magnetic sensor operative to generate in said source signal a bipolar pulse responsive to the passing of a print band timing mark;
- RC filter means including a series resistance and a shunt capacitor for providing a d.c. reference voltage substantially equal to the nominal d.c. level of said source signal;
- amplifier means having inverting and non-inverting inputs and operative to generate an output which is a function of the difference of the inputs;
- means for applying said d.c. reference voltage to said inverting input;
- circuit means for applying to said non-inverting input, through a voltage follower amplifier and a first mixing resistance, a first signal component which is a linear function of said source signal;
- means for applying to said non-inverting input, through a second mixing resistance and a diode, a second signal component which is a non-linear function of the amplifier output
- whereby said amplifier responds to the passage of print band timing marks by generating a squarewave signal having one edge which is precisely aligned with the nominal zero crossing of the bipolar pulse generated by said sensing circuit.
4 more elements
Dependencies are inferred from the claim text.