Claims
- 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.
- 2. The printing device according to claim 1, wherein said control circuit is responsive to the signal output by said magnetic field sensor for setting a print gap of said printing device.
- 3. The printing device according to claim 1, wherein said control circuit is responsive to the signal output by said magnetic field sensor for determining a position of the driven print wire.
- 4. The printing device according to claim 1, wherein said control circuit is responsive to the signal output by said magnetic field sensor for determining a compressibility of a printing medium.
- 5. The printing device according to claim 4, wherein said control-circuit is configured to use the determined compressibility for setting a print gap of said printing device.
- 6. The printing device according to claim 4, wherein said control circuit is configured to use the determined compressibility for setting a current for driving print wires in said print head during printing operations.
- 7. The printing device according to claim 1, wherein said control circuit is responsive to the signal output by said magnetic field sensor for determining a position of said driven print wire as a function of time.
- 8. The printing device according to claim 7, further comprising:
a memory for storing data indicative of the position of said driven print wire as a function of time.
- 9. The printing device according to claim 8, wherein said control circuit is configured to periodically determine the position of said driven wire as a function of time and to compare data from these periodic determinations with the data stored in said memory.
- 10. The printing device according to claim 9, further comprising:
a control panel for communicating data indicative of the results of the comparison.
- 11. The printing device according to claim 9, wherein said control circuit is configured to control said printing device based on the results of the comparison.
- 12. The printing device according to claim 1, wherein said magnetic field sensor comprises a Hall sensor.
- 13. The printing device according to claim 12, wherein the Hall sensor is a ratiometric Hall sensor.
- 14. The printing device according to claim 1, wherein the driven print wire is in contact with a first end of a print wire armature that is arranged to pivot around a first pole end of a yoke and the air gap associated with the driven print wire is an air gap between a second end of said print wire armature and a second pole end of said yoke.
- 15. The printing device according to claim 14, wherein said print wire driving circuitry comprises a coil wrapped around a portion of said yoke and relay circuitry for selectively supplying a voltage to terminals of said coil.
- 16. The printing device according to claim 1, further comprising:
an analog-to-digital converter for converting the signal indicative of the magnitude of the sensed magnetic field to a digital signal and outputting the digital signal to said circuit.
- 17. The printing device according to claim 16, wherein said analog-to-digital converter comprises a one-bit analog-to-digital converter.
- 18. The printing device according to claim 16, wherein said analog-to-digital converter is self-calibrating.
- 19. The printing device according to claim 1, further comprising:
a biasing member for biasing said print wire in a direction away from a printing medium, wherein said print wire driving circuit drives said print wire against the biasing of said biasing member with a current sufficient to prevent said print wire from snapping back due to the biasing of said biasing member when said print wire contacts the printing medium.
- 20. The printing device according claim 1, wherein said printing device is an impact printer.
- 21. A method of setting a print gap for a printing device, comprising:
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.
- 22. The method according to claim 21, wherein the print gap is set by moving a print head of said printing device a predetermined distance from the position of said print head at the time when the magnetic flux sensed by the Hall sensor exceeds the predetermined value.
- 23. The method according to claim 22, wherein the driven print wire is in contact with a first end of said print wire armature and said print wire armature is arranged to pivot around a first pole end of a yoke, the variable air gap being an air gap between a second end of said print wire armature and a second pole end of said yoke.
- 24. The method according to claim 21, wherein said printing device is an impact printer.
- 25. A method for setting a print gap between a print head of a printing device and a printing medium, comprising:
automatically determining a compressibility of the printing medium; and setting the print gap based on the determined compressibility.
- 26. The method according to claim 25, wherein the compressibility is automatically determined using a magnetic field sensor.
- 27. The method according to claim 26, wherein the magnetic field sensor comprises a Hall sensor.
- 28. The method according to claim 25, wherein said printing device is an impact printer.
- 29. A method for setting a current for driving a print wire in a printing device, comprising:
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.
- 30. The method according to claim 29, wherein the compressibility is automatically determined using a magnetic field sensor.
- 31. The method according to claim 30, wherein the magnetic field sensor comprises a Hall sensor.
- 32. The method according to claim 29, wherein said printing device is an impact printer.
Parent Case Info
[0001] This application claims priority from provisional Application No. 60/121,963, filed Feb. 25, 1999, the contents of which are incorporated herein by reference.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60121963 |
Feb 1999 |
US |
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/US00/04805 |
Feb 2000 |
US |
Child |
09811692 |
Mar 2001 |
US |