Developing roller, developing apparatus comprising the developing roller, and method for providing the developing roller
Developing roller comprising a conductive mandrel with at least an elastic conductive base layer and a charge providing layer. The base layer is located closer to the mandrel than the charge providing layer. The base layer is roughened before the charge providing layer is applied to the base layer.
1. A developing roller comprising:
a conductive mandrel with at least an elastic conductive base layer and a charge providing layer, wherein:
the base layer is located closer to the mandrel than the charge providing layer;
the base layer is roughened by blasting before the charge providing layer is applied to the base layer;
before the charge providing layer is applied to the base layer, the base layer has a surface roughness Ra of 0.1 <Ra <3; and
a ratio between the surface roughness of the base layer in axial direction and radial direction of the developing roller is 0.5 <Ra (axial direction)/Ra (radial direction) <2.
2. The developing roller according to claim 1 , wherein the charge providing layer is applied directly to the roughened base layer.
3. The developing roller according to claim 1 , wherein a top layer is applied to the charge providing layer.
4. The developing roller according to claim 1 , wherein the base layer comprises rubber.
5. The developing roller according to claim 4 , wherein the rubber is silicone rubber.
6. A developing apparatus comprising:
a toner container for containing therein a non magnetic toner for developing an electrostatic latent image formed on a surface of an image bearing member, and
the developing roller according to claim 1 for transporting the non magnetic toner from said toner container, while causing the toner to adhere to the surface of the developing roller.
7. A method for providing a developing roller comprising a conductive mandrel with at least an elastic conductive base layer and a charge providing layer, comprising:
locating the base layer closer to the mandrel than the charge providing layer,
roughening the base layer by blasting and, after that,
applying the charge providing layer to the base layer, wherein before the charge providing layer is applied to the base layer, the base layer has a surface roughness Ra of 0.1 <Ra <3 and wherein a ratio between the surface roughness of the base layer in axial direction and radial direction of the developing roller is 0.5 <Ra (axial direction)/Ra (radial direction) <2.
8. The method according to claim 7 , wherein the charge providing layer is applied directly to the roughened base layer.
9. The method according to claim 7 , wherein a top layer is applied to the charge providing layer.