Doctor blade for toner cartridge developer roller
A metering blade confronts the developer roller of a toner cartridge with a working face and associated upstream corner that is accurately controlled with respect to the developer roller to achieve a desired gap therebetween. More particularly, the quality of toner metering is determined through an appropriate technique and the angle of the bottom working face and working corner is varied using appropriate computer-controlled machining techniques to adjust the location of the corner with respect to the radial centerline of the roller at all points along the axial direction. In an illustrative embodiment, the blade's working face is formed to create a setback that is compound angle in two orthogonal directions. This compound angle reorients the upstream corner of the working face to compensate for irregular metering and electrostatic differences across the roller surface, particularly where toner is greater on one side of the roller than the other, opposing side.
1. A metering blade for a toner cartridge having a developer roller with an axis of rotation extending in an axial direction comprising:
an upstream face relative to an upstream-to-downstream direction of developer roller rotation; and
a setback formed in the upstream face along a predetermined portion of the upstream face in the axial direction, the setback defining an upstream corner at each point along the axial direction that is positioned with respect to a centerline taken through the axis so as to provide a predetermined gap characteristic between the roller surface and the corner at each point along the axial direction, whereby metering of toner by the gap is controlled;
wherein the setback comprises a compound angle that varies from a first end of the blade to an opposing second end of the blade in each of two orthogonal directions with respect to the axial direction.
2. The metering blade as set forth in claim 1 wherein the setback is constructed according to a process, comprising the steps of:
a) analyzing a level of toner across the roller in the axial direction delivered to an image drum;
b) computing a profile of the setback in response to the analyzing step; and
c) forming the setback on the blade in accordance with the computed profile.
3. The process as set forth in claim 2 further comprising the step of:
d) providing the blade, subsequent to step (c) to the toner cartridge and analyzing a level of toner across the roller in the axial direction delivered to the image drum, and thereafter adjusting the setback on the blade according to a predetermined rule if the level of toner across the roller is unacceptable.
4. The process as set forth in claim 3 further comprising (e) repeating step (d) until the level of toner across the roller is acceptable.
5. The process as set forth in claim 4 further comprising storing an adjusted profile derived from step (e) and forming a standard setback in a blade of a further cartridge in accordance with the stored adjusted profile.