Electrographic development method and apparatus
View Patent ↗The invention relates generally to processes for electrographic image development. An electrographic development apparatus is provided wherein a film is adjacent a cylindrical toning shell and a mixture of toner and carrier is particles disposed on the cylindrical toning shell in contact with the film. The cylindrical toning shell is closest to the film at a first location, the mixture of toner and carrier particles being movable through the first location with a flow direction. A magnetic core disposed within the cylindrical toning shell offset toward the cylindrical shell such that a magnetic field strength is greater at the second location than the first location.
1. An electrographic development apparatus, comprising:
a film;
a cylindrical toning shell having an toning shell outer circumference;
a mixture of toner and carrier particles disposed on the cylindrical toning shell in contact with the film;
the cylindrical toning shell being closest to the film at a first location,
the mixture of toner and carrier particles being movable through the first location with a flow direction; and
a magnetic core disposed within the cylindrical toning shell that provides a magnetic field strength of varying magnitude around the toning shell outer circumference,
the magnetic field strength having a first time-averaged absolute magnitude at the first location, and
a second time-averaged absolute magnitude at a second location a distance from the first location in the flow direction,
the second time-averaged absolute magnitude being at least 25 gauss greater than the first time-averaged absolute magnitude.
2. The apparatus of claim 1 , the second time-averaged absolute magnitude being at least 50 gauss greater than the first time-averaged absolute magnitude.
3. The apparatus of claim 1 , the second time-averaged absolute magnitude being at least 75 gauss greater than the first time-averaged absolute magnitude.
4. The apparatus of claim 1 , the second time-averaged absolute magnitude being at least 100 gauss greater than the first time-averaged absolute magnitude.
5. The apparatus of claim 1 , the second time-averaged absolute magnitude being at least 125 gauss greater than the first time-averaged absolute magnitude.
6. The apparatus of claim 1 , the second time-averaged absolute magnitude is a maximum time-averaged absolute magnitude of magnetic field strength around the toning shell outer circumference.
7. The apparatus of claim 1 , wherein the magnetic core is either fixed or rotatable.
8. The apparatus of claim 1 , wherein the cylindrical toning shell is either fixed or rotatable.
9. The apparatus of claim 1 , wherein the magnetic core is cylindrical, comprising an outer magnetic core circumference and a multitude of magnets of uniform strength with alternating north and south poles disposed around the outer magnetic core circumference.
10. The apparatus of claim 1 , wherein the magnetic core is offset toward the cylindrical toning shell such that the magnetic core is closest to the cylindrical toning shell at the second location.
11. The apparatus of claim 1 , wherein the carrier particles comprise hard magnetic carrier particles.
12. The apparatus of claim 1 , wherein the toner particles comprise MICR toner particles.
13. An electrographic development apparatus, comprising:
a film;
a cylindrical toning shell having an toning shell outer circumference;
a mixture of toner and carrier particles disposed on the cylindrical toning shell in contact with the film;
the cylindrical toning shell being closest to the film at a first location,
the mixture of toner and carrier particles being movable through the first location with a flow direction; and
a magnetic core disposed within the cylindrical toning shell that provides a magnetic field strength of varying magnitude around the toning shell outer circumference,
the magnetic field strength having a first time-averaged absolute magnitude at the first location, and
a second time-averaged absolute magnitude at a second location a distance from the first location in the flow direction,
the second time-averaged absolute magnitude being at least 2.5% greater than the first time-averaged absolute magnitude.
14. The apparatus of claim 13 , the second time-averaged absolute magnitude being at least 5% greater than the first time-averaged absolute magnitude.
15. The apparatus of claim 13 , the second time-averaged absolute magnitude being at least 7.5% greater than the first time-averaged absolute magnitude.
16. The apparatus of claim 13 , the second time-averaged absolute magnitude being at least 10% greater than the first time-averaged absolute magnitude.
17. The apparatus of claim 13 , the second time-averaged absolute magnitude being at least 12.5% greater than the first time-averaged absolute magnitude.
18. The apparatus of claim 13 , wherein the second time-averaged absolute magnitude is a maximum time-averaged absolute magnitude of magnetic field strength around the toning shell outer circumference.
19. The apparatus of claim 13 , wherein the magnetic core is either fixed or rotatable.
20. The apparatus of claim 13 , wherein the cylindrical toning shell is either fixed or rotatable.
21. The apparatus of claim 13 , wherein the magnetic core is cylindrical, comprising an outer magnetic core circumference and a multitude of magnets of uniform strength with alternating north and south poles disposed around the outer magnetic core circumference.
22. The apparatus of claim 13 , wherein the magnetic core is offset toward the cylindrical toning shell such that the magnetic core is closest to the cylindrical toning shell at the second location.
23. The apparatus of claim 13 , wherein the carrier particles comprise hard magnetic carrier particles.
24. The apparatus of claim 13 , wherein the toner particles comprise MICR toner particles.
25. An electrographic development method, comprising:
moving a mixture of toner and carrier particles disposed on a cylindrical toning shell in contact with a film in a film direction through a first location wherein the cylindrical toning shell is closest to the film,
a magnetic core being disposed within the cylindrical toning shell that provides a magnetic field strength of varying magnitude around the toning shell outer circumference,
the magnetic field strength having a first time-averaged absolute magnitude at the first location, and
a second time-averaged absolute magnitude at a second location a distance from the first location in the flow direction,
the second time-averaged absolute magnitude being at least 25 gauss greater than the first time-averaged absolute magnitude.
26. The method of claim 25 , the second time-averaged absolute magnitude being at least 50 gauss greater than the first time-averaged absolute magnitude.
27. The method of claim 25 , the second time-averaged absolute magnitude being at least 75 gauss greater than the first time-averaged absolute magnitude.
28. The method of claim 25 , the second time-averaged absolute magnitude being at least 100 gauss greater than the first time-averaged absolute magnitude.
29. The method of claim 25 , the second time-averaged absolute magnitude being at least 125 gauss greater than the first time-averaged absolute magnitude.
30. The method of claim 25 , comprising rotating the magnetic core.
31. The method of claim 25 , comprising rotating the toning shell.
32. The method of claim 25 , wherein the carrier particles comprise hard magnetic carrier particles.
33. The method of claim 25 , wherein the toner particles comprise MICR toner particles.
34. An electrographic development method, comprising:
moving a mixture of toner and carrier particles disposed on a cylindrical toning shell in contact with a film in a film direction through a first location wherein the cylindrical toning shell is closest to the film,
a magnetic core being disposed within the cylindrical toning shell that provides a magnetic field strength of varying magnitude around the toning shell outer circumference,
the magnetic field strength having a first time-averaged absolute magnitude at the first location, and
a second time-averaged absolute magnitude at a second location a distance from the first location in the flow direction,
the second time-averaged absolute magnitude being at least 2.5% greater than the first time-averaged absolute magnitude.
35. The method of claim 34 , the second time-averaged absolute magnitude being at least 5% greater than the first time-averaged absolute magnitude.
36. The method of claim 34 , the second time-averaged absolute magnitude being at least 7.5% gauss greater than the first time-averaged absolute magnitude.
37. The method of claim 34 , the second time-averaged absolute magnitude being at least 10% gauss greater than the first time-averaged absolute magnitude.
38. The method of claim 34 , the second time-averaged absolute magnitude being at least 12.5% greater than the first time-averaged absolute magnitude.
39. The method of claim 34 , comprising rotating the magnetic core.
40. The method of claim 34 , comprising rotating the toning shell.
41. The method of claim 34 , wherein the carrier particles comprise hard magnetic carrier particles.
42. The method of claim 34 , wherein the toner particles comprise MICR toner particles.