Method and apparatus for correcting non-uniform banding and residual toner density using feedback control

A feedback control system for controlling periodic defects caused by a density variation on a receiving member in a xerographic marking device, comprising:

• optical sensors arranged on the receiving member, the optical sensors determining a toner density on the receiving member;
• at least one of electromechanical actuators and exposure actuators disposed in correspondence with the receiving member in the xerographic marking device;
• and
• a controller, coupled to the optical sensors and the at least one of electromechanical actuators and exposure actuators, that:
• automatically determines the extent of periodic defects in a process direction and in a cross-process direction on the receiving member by comparing the determined toner density to a reference toner density value;
• and
• automatically adjusts the toner density, based on a result obtained from the comparison of the measured toner density to the reference toner density value, by actuating at least one of electromechanical actuators and exposure actuators.

A method of determining periodic defects caused by a density variation on a xerographic marking device, comprising:

• creating at least one test pattern;
• imaging the at least one test pattern;
• determining a signal obtained during imaging of the at least one test pattern by optical sensors arranged on a photoreceptor;
• processing the signal obtained during imaging;
• and
• determining an amount of periodic defects in a process direction and in a cross-process direction based on the processed signal.

A system of determining periodic defects caused by a density variation on a xerographic marking device, comprising:

• optical sensors arranged on a receiving member;
• and
• a controller coupled to the optical sensors that:
• images at least one test pattern to determine a signal provided by the optical sensors arranged on the receiving member during imaging of the at least one test pattern;
• processes the signal obtained during imaging;
• and
• determines an amount of periodic defects in a process direction and in a cross-process direction based on the processed signal.

A xerographic marking device, comprising:

• at least one of an array-type sensor and point sensors arranged on a receiving member, the at least one of an array-type sensor and point sensors determining a toner density on the receiving member;
• at least one of electromechanical actuators and exposure actuators disposed in correspondence with the receiving member in the xerographic marking device;
• and
• a controller, coupled to the at least one of an array-type sensor and point sensors and the at least one of electromechanical actuators and exposure actuators, that:
• automatically determines the extent of periodic defects in a process direction and a cross-process direction on the receiving member by comparing the determined toner density to a reference toner density value;
• and
• automatically adjusts the toner density, based on a result obtained from the comparison of the measured toner density to the reference toner density value, by actuating at least one of electromechanical actuators and exposure actuators.

A machine-readable medium that provides instructions for controlling periodic defects caused by a density variation in a receiving member of a xerographic marking device, the instructions, when executed by a processor, cause the processor to perform operations comprising:

• determining a toner density on the receiving member;
• automatically determining the extent of periodic defects in a process direction and a cross-process direction on the receiving member by comparing the determined toner density to a reference toner density value;
• and
• automatically adjusting the toner density based on a result obtained from the comparison of the measured toner density to the reference toner density value.

A machine-readable medium that provides instructions for controlling periodic defects caused by a density variation in a receiving member of a xerographic marking device, the instructions, when executed by a processor, cause the processor to perform operations comprising:

• creating at least one test pattern;
• imaging the at least one test pattern;
• determining a signal obtained during imaging of the at least one test pattern by optical sensors arranged on a photoreceptor;
• processing the signal obtained during imaging;
• and
• determining an amount of periodic defects in a process direction and a cross-process direction based on the processed signal.