Developer roller for liquid electrophotographic printing
In one example, a developer roller for liquid electrophotographic printing includes a cylindrical metal inner core, a rigid conductive plastic outer core surrounding the inner core, and a compliant exterior surrounding the outer core.
1. A developer roller for liquid electrophotographic printing, comprising:
a conductive cylinder having a cylindrical surface, a first end distinct from and intersecting the cylindrical surface, and a second end distinct from and intersecting the cylindrical surface opposite the first end;
a compliant exterior around the cylindrical surface to present a film of liquid electrophotographic ink to a photoconductor during printing; and
rigid conductive plastic sandwiched between the cylindrical surface and the exterior and covering the first and second ends of the cylinder.
2. The roller of claim 1 , where the plastic has a resistivity below 100Ω -cm.
3. The roller of claim 2 , where the exterior comprises a resistive exterior having a resistivity of at least 0.5MΩ-cm.
4. The roller of claim 1 , where the plastic comprises a carbon filled plastic.
5. The roller of claim 4 , where the carbon fill includes carbon fibers.
6. The roller of claim 1 , where the exterior covers at least some of each end of the plastic covering respective first and second ends of the cylinder.
7. The roller of claim 6 , comprising a shaft extending axially from each end of the cylinder through the plastic such that there is plastic between each shaft and the exterior.
8. A developer roller for liquid electrophotographic printing, comprising:
a multi-part rigid conductive core that includes a cylindrical metal inner core and a rigid conductive plastic outer core surrounding the inner core; and
a resistive compliant exterior surrounding the outer core.
9. The roller of claim 8 , where:
the outer core is formed directly on the inner core; and
the exterior is formed directly on the outer core.
10. The roller of claim 9 , where:
the outer core is a layer of carbon filled plastic on the inner core; and
the exterior is a layer of polyurethane on the layer of carbon filled plastic.
11. The roller of claim 10 , where:
the inner core includes a cylindrical surface, a first end distinct from and intersecting the cylindrical surface, and a second end distinct from and intersecting the cylindrical surface opposite the first end;
the layer of carbon filled plastic covers the first and second ends of the inner core; and
the polyurethane exterior wraps around each end of the layer of carbon filled plastic covering respective first and second ends of the inner core.
12. The roller of claim 11 , comprising a shaft extending axially from each end of the inner core through the layer of carbon filled plastic such that there is carbon filled plastic between each shaft and the polyurethane exterior.
13. A developer unit for a liquid electrophotographic printer, comprising:
a developer roller to present LEP ink to a photoconductor; and
a squeegee roller to squeegee ink on the developer roller;
the developer roller including a multi-part rigid conductive core that includes:
a cylindrical metal inner core and a rigid conductive plastic outer core surrounding the inner core; and
a resistive compliant exterior surrounding the outer core.
14. The developer unit of claim 13 , where:
the outer core is a carbon filled plastic on the inner core; and
the exterior is a polyurethane on the outer core.