Konica Minolta, Inc.

Hirohisa Shirai

Masato Kimura

Hisashi Murata

Kazuki Kobori

Tomohiro Kato

An image forming apparatus has: an image supporting member, a charger, a power source unit, an amperometric detector, and a processor. The power source unit applies a plurality of charging voltages, which includes alternating voltages respectively, to the charger sequentially while no print medium is fed. The alternating voltages have different peak-to-peak voltages for a forward discharge range and different peak-to-peak voltages for a reverse discharge range, respectively. The amperometric detector detects values of alternating current flowing in the charger during application of the charging voltages. The processor derives characteristic lines of alternating current value with respect to alternating voltage for the forward discharge range and for the reverse discharge range, respectively, from the values detected by the amperometric detector. The processor derives a peak-to-peak voltage to be used in a process in a different way depending on a difference in slope between the characteristic lines.

Image forming apparatus with a proximity charger

An image forming apparatus that forms an image on a medium includes: an image carrying member; a charging unit disposed in proximity to the image carrying member; a power supply unit configured to sequentially apply a plurality of charging voltages to the charging unit when the medium is not fed through; a current detecting unit configured to detect an AC value flowing through the charging unit; a processing unit configured to perform first charging voltage determination control to derive a peak-to-peak voltage value to be used in a process; and a storage unit configured to pre-store a reference peak-to-peak voltage value for each wastage level of the image carrying member, wherein the processing unit: prohibits execution of the first charging voltage determination control and performs second charging voltage determination control; and obtains a reference peak-to-peak voltage value and derives a peak-to-peak voltage value to be used in the process.

Image forming apparatus

An image forming apparatus has: an image supporting member; a charger in proximity to the image supporting member; a power source unit configured to apply charging voltages to the charger sequentially, the charging voltages including alternating voltages having different peak-to-peak voltages, respectively; an amperometric detector configured to detect values of alternating currents flowing in the charger during application of the charging voltages; and a processor configured to carry out a first charging voltage determination process or a second charging voltage determination process requiring a shorter time than the first charging voltage determination process selectively based on a detection result of the amperometric detector. The processor carries out the first charging voltage determination process or the second charging voltage determination process selectively in accordance with a difference between an ambient temperature at a previous time of carrying out the first charging voltage determination process and a current ambient temperature.

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Toyokawa, Japan

Hirohisa Shirai