Eastman-kodak Company

Nexpress Solutions, Inc.

Charles Herbert Hasenauer

Kenneth Joseph Brown

Andreas Dickhoff

Donald Saul Rimai

Joseph John Furno

Soenke Schmidt

Developer density in an electrophotographic system is measured. The developer includes toner particles and magnetic carrier particles. First and second mutually-insulated electrodes define a working volume between them through which developer passes without contacting the first electrode. An AC voltage or current source is connected to the electrodes. An inductor is connected in series with a voltage source, or an inductor is provided in parallel with a current source. The voltage or current is applied and corresponding current or voltage across the electrodes is measured. The density of the developer in the working volume is automatically determined using a processor responsive to the measured current or voltage and the applied bias.

Resonant-frequency measurement of electrophotographic developer density

Developer density is measured in an electrophotographic system. First and second electrodes are disposed to define a working volume between them through which developer passes without contacting the first electrode, wherein the electrodes are electrically insulated from each other by the working volume. One terminal of an AC voltage (current) source having a selected frequency is connected to one of the electrodes. An inductor is connected in series (parallel) with the voltage source, so that the source provides the AC bias (current) across the electrodes through (across) the inductor. The AC is applied and the current (voltage) across the electrodes is measured. The density of the developer in the working volume is automatically determined using a processor responsive to the measured current (voltage) and the applied bias (current).

A piezoelectric crystal adjacent to a development member in an electrophotographic printer has an electrode on it facing the development member. An AC bias is applied across the crystal while a DC bias is applied between the electrode and the development member to measure toner-mass deposition rate. An AC bias is then applied between the electrode and the development member to measure developer flow rate. The toner concentration of the developer is determined using the measured toner mass-deposition rate and developer flow rate.

Determining developer toner concentration in electrophotographic printer

Developer toner concentration in an electrophotographic system is measured. Two sensors, one before and one after the toning zone in the direction of rotation of the development member, each include respective electrodes that form a respective capacitance between the respective electrode and the development member. A voltage source selectively applies respective AC biases across the sensors and the respective currents across the sensors are measured. A controller causes an electrostatic latent image to be produced on the photoreceptor and causes the development member to rotate and the photoreceptor to move. While the development member is rotating, the processor receives the measured currents and computes toner concentration using the respective received currents and the pixel data. The developer flow rate can be adjusted, or toner added to the developer, in response to the determined toner concentration.

Electrophotographic developer toner concentration measurement

An apparatus and method for powering opposing corona chargers for discharging moving receiver sheets. The discharging capacity of the chargers is expanded by adding a high voltage DC offset to a current regulated, AC voltage limited power supply.

Current regulated, voltage limited, AC power supply with DC offset for corona chargers

A method and apparatus for provision of a power supply that combines the advantages of current regulation with voltage limitation to enable corona chargers that can be run at higher current regulated set points for lower resistance sheets. The voltage limit will protect against arcing when high resistance media is used. This wider operation window can be provided without the need to track sheet types in the process and shift the operating set points, which would result in much more complicated machine control algorithms. The regulation and limit reference controls retain the ability of changing the operating set points of the power supply, such that it can be adapted to alternate physical configurations of the discharging system and the printing system.

Current regulated voltage limited high voltage power supply for corona charger

A method and apparatus for identifying potential problems within systems having rotating biased components. The system employs diagnostics to the rotating biased components to provide status feedback to the machine's control unit when any type of bias fault has occurred. The system then responds to this fault signal making it possible to stop operation and alert the machine operator. The present invention also discloses a method for detecting open load, over load, shorted load and intermittent contact with the load or arcing conditions, as well as power supply output failure in a bias system. A digital signal that may be may be sensed by interrupt or sampling methods and filtered appropriately with software is provided to a machine control system. The result is that bias failures may be detected automatically by machine control. The system also provides a method to alert the operator service personnel on which area of the machine to service.

High voltage bias feedback for diagnostic purposes

EMI shielding for high voltage interconnection cables in corona charging systems. The corona charger includes a high voltage conductor to transmit energy from a power supply to the corona charger. A high frequency voltage, grounded conductive shield surrounds the high voltage conductor. The grounded conductive shield is formed from a conductive fabric having at least one grounding tab formed from said conductive fabric. A foam spacer is located between the shield and the conductor.

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Rochester, NY, United States of America

Charles Herbert Hasenauer