Abstract: A particularly configured aperiodic grid for a grid-controlled AC corona charger for uniformly charging a dielectric member, of an electrostatographic reproduction apparatus, moving along a travel path in operative relation to the corona charger. The corona charger includes an insulating housing and an electrically biased grid, in which the grid transparency is larger than a nominal transparency at the upstream edge of the charger grid, transparency is nominal at the center of the grid, and transparency is smaller than nominal at the downstream edge of a charger grid. The invention, which has been demonstrated for negative primary charging, preferably uses a trapezoidal AC waveform having a DC offset for corona excitation, and may be practiced over a large range of process speeds. The invention is also practiced using trapezoidal waveforms having negative duty cycles in the range 50% (conventional AC) to 90% (negative DC).

Abstract: A corona charger and method and apparatus for corona charging features an insulative shield and an electrically biased grid electrode spaced from the shield. One or more substantially bare corona wires are located between the grid electrode and the shield. The corona wires are electrically biased with an AC voltage. An electrically biased highly conductive buried floor electrode forms a part of the charger and has a surface located between the one or more corona wires and the shield. An insulating layer is located between the corona wires and the surface of the buried floor electrode so that there is no exposure of the buried floor electrode in a direct line of sight from a corona wire.

Abstract: A corona charger for depositing an electrostatic charge on a charge retentive surface, without the creation of sheeting defects, the charger includes a coronode, and a power supply operating in cycles and providing in each of the cycles electrical power to the coronode to produce a net positive charging current with voltage to the coronode from the power supply operating in a portion of each cycle with a positive polarity to generate positive corona emissions. The power supply operates so that an AC component of the voltage provided by the power supply has a positive polarity in the range of about 60% to about 85% of each cycle. When operating in a broader range of greater than 50% but less than 100%, DC equivalent current to the coronode is controlled below a value causing sheeting.

Abstract: An environmental control for a charger utilized in an electrostatographic reproduction apparatus including a movable dielectric support upon which images of information to be reproduced are formed as the dielectric support is moved into operative relation with electrostatic process stations. The charger environmental control system as disclosed includes a housing associated with charger. The housing is selectively provided with a positive pressure air flow or a negative pressure air flow. The positive pressure air flow and the negative pressure air flow are controlled such that during movement of the dielectric support of the reproduction apparatus, positive pressure air flow is provided to the housing, and when such dielectric support is at rest, negative pressure air flow is provided to the housing.

Abstract: This invention pertains to a sawtooth AC charger (10) in which an AC voltage signal applied to sawtooth blades (12) has a duty cycle greater than 50%. Duty cycles above about 70% increase the uniformity of negative charging without significantly increasing the peak voltage to the sawtooth blades.

Abstract: This invention pertains to an AC charger (10) in which an AC voltage waveform applied to a corona wires (12) has a duty cycle of between 50% and 90%. This increases the efficiency of the charger without increasing the signal-to-noise ratio. In one embodiment, the AC voltage waveform is asymmetric.