Abstract: 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.

Abstract: 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).

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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).

Abstract: Developer flow rate over a rotatable development member in an electrophotographic system is measured. An electrode and the development member define a capacitive working volume between them through which developer moves. A voltage source electrically connected to the electrode and the development member selectively applies an AC bias across the working volume, and a meter measures the currents across the working volume while the bias is applied. A controller causes the development member to stop supplying toner to the photoreceptor, and to rotate. While the development member is rotating, the controller records the current measured by the meter. Developer flow rate is computed using the measured current. The developer flow rate can be adjusted in response to the computed flow rate.

Abstract: 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.

Abstract: An apparatus for measuring developer density in an electrophotographic system. A first electrode and a second electrode are disposed to define a working volume between them through which developer moves without contacting the first electrode, wherein the electrodes are electrically insulated from each other by the working volume. A voltage source selectively applies an AC bias across the electrodes. A measuring device measures the current across the electrodes while the bias is applied. A processor is adapted to automatically determine the density of the developer in the working volume based on the measured current and the applied bias.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method and apparatus for EMI shielding that is economical and adaptable on high voltage interconnection cables in corona charging systems. The shield can be implemented without loss of efficiency in the transmission of low-level currents from the power source to the charging device.

Abstract: This invention discloses 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 imaging and alert the machine operator that bias faults may adversely affect the image quality of the prints being produced. 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.

Abstract: 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.