Abstract: This invention provides a timing wheel assembly for controlling the timing of toner cartridge operation that is fixedly attached to a shaft of a toner tank agitator and that is operatively connected to a drive gear of a toner cartridge mounted coaxially on the shaft with the timing wheel movable between a first stop and a second stop relative to the drive gear to define rotational “dwell” range having a predetermined arcuate distance with a pair of springs of differing strengths. The first spring, of a first strength (first spring constant) biases the timing wheel against the first stop and the second spring of a second strength (second spring constant) is engaged by the timing wheel at higher resistance levels. In this manner, the first spring ensures that an appropriate dwell and snapback motion occurs at lower toner levels and the second spring (in combination with the first) provides heavier resistance and stronger rotational resistance/earlier snapback at higher toner levels.

Abstract: This invention provides a metering blade that 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 (such as analysis of print quality) and the angle of the bottom working face and working corner is varied using appropriate computer-controlled machining (or other metal-forming) techniques to adjust the location of the corner with respect to the radial center-line 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 (with respect the lengthwise direction, parallel to the roller axis).

Abstract: An improved developer roll magnet for a toner cartridge provides a strip of magnetic material that extends axially along a surface of the developer roll magnet located coaxially within a developer roll sleeve. The strip of magnetic material can be seated within a groove in the magnet and can extend radially outwardly above the surface of the magnet. The strip is generally adhered to the magnet by mutual magnetic attraction and can be made adjustable to move toward and away from the developer roll sleeve. The strip is typically located adjacent a nip formed between the developer roll sleeve and the image transfer drum of the cartridge to provide enhanced toner release for greater print yield and quality.