Print gap setting for a printing device
First Claim
1. A printing device, comprising:
- a print head comprising print wires;
print wire driving circuit for selectively driving one of said print wires;
a magnetic field sensor positioned in the vicinity of a variable air gap associated with the driven print wire, said magnetic field sensor outputting a signal indicative of the magnitude of the sensed magnetic field; and
a control circuit responsive to the signal output by said magnetic field sensor.
1 Assignment
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Accused Products
Abstract
A print head is attached to a stepper motor that moves the print head toward and away from the surface of a printing medium. During a gap setting operation, a controller controls the stepper motor to move the print head to a maximum distance away from the surface of the printing medium. A print wire actuator coil for the print wire used in the gap setting operation is then energized. The print head is then positioned over the printing medium and the controller controls the stepper motor to move the print head in towards the printing medium. When the energized print wire touches the printing medium, the print wire begins to be pushed back into the print head. As the wire is pushed back, an air gap between a yoke and a print wire armature is created. The opening of the air gap increases the amount of flux detected by a Hall sensor. When the output voltage of the Hall sensor reaches a predetermined level, the controller determines that the print wire has pressed the ribbon and printing medium against the platen. The controller then controls the stepper motor to establish the desired printing gap (e.g., by stepping back a predetermined number of steps).
5 Citations
32 Claims
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1. A printing device, comprising:
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a print head comprising print wires;
print wire driving circuit for selectively driving one of said print wires;
a magnetic field sensor positioned in the vicinity of a variable air gap associated with the driven print wire, said magnetic field sensor outputting a signal indicative of the magnitude of the sensed magnetic field; and
a control circuit responsive to the signal output by said magnetic field sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of setting a print gap for a printing device, comprising:
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driving a print wire attached to a print wire armature when said print wire is spaced from a printing medium;
moving said print wire toward said printing medium;
using a Hall sensor, sensing a magnetic flux in the vicinity of a variable air gap associated with said driven print wire; and
setting the print gap based on a signal generated when the magnetic flux sensed by said Hall sensor in the vicinity of the variable gap exceeds a predetermined value. - View Dependent Claims (22, 23, 24, 26, 27, 28, 30, 31, 32)
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25. A method for setting a print gap between a print head of a printing device and a printing medium, comprising:
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automatically determining a compressibility of the printing medium; and
setting the print gap based on the determined compressibility.
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29. A method for setting a current for driving a print wire in a printing device, comprising:
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determining a compressibility of a printing medium on which the print wire prints; and
setting the current for driving the print wire during printing operations based on the determined compressibility.
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Specification