Hammer drive circuit using power MOSFETs
AssigneeInternational Rectifier Corporation
InventorBrian R. Pelly
Life of this patent
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Abstract
An energizing circuit for printer hammer drive coils is provided in which a single MOSFET transistor and a single diode is employed for each drive coil. Two voltage source means, one of which may be a capacitor, are connected in series. The drive coil is connected in series with the single MOSFET transistor and one of the voltage sources and is energized when the transistor is on. The drive coil discharges in a series circuit including the diode and the other of the voltage sources and charges the later voltage source when the transistor is off. An energy recuperation circuit is disclosed for receiving energy from the later voltage source and returning it to the first voltage source.
Claims16
A circuit for a repetitively energized inductive load;
- said circuit including a transistor, a diode, first and second d-c voltage source means, and transistor control circuit means operable to turn said transistor on and off and to cycle said transistor between on and off conditions when the current through said inductive load attempts to fall below a prescribed minimum and rise above a pescribed maximum value respectively, or in response to alternatively derived timing signals which achieve essentially the same result, said transistor being cycled at a cycle rate of greater than about 100 kHz;
- said first voltage source means, said inductive load and said transistor connected in a first closed series relationship;
- said first and second voltage source means connected in series with one another with additive polarities, whereby, when said transistor is on, current flows from said first voltage source means, through said inductive load, and when said transistor then turns off, current flows through said diode and into said second voltage source means in a direction to oppose said current flow.
Dependencies are inferred from the claim text.