Electrophotographic image forming apparatus

摘要

An image forming apparatus includes an image forming unit, an image carrier carrying on a surface thereof a developer image formed by the image forming unit, a transfer unit for transferring the developer image carried on the image carrier to a recording medium, a voltage supplying unit for supplying a transfer voltage to the transfer unit, a transfer current measuring unit for measuring a transfer current value at a time that a prescribed voltage is applied from the voltage supplying unit to the transfer unit in a state that no recording medium exists in the transfer unit, a resistor serially coupled between the transfer current measuring unit and the transfer unit, a memory unit for memorizing electrical character information of the recording medium, and a controller for controlling the transfer voltage supplied from the voltage supplying unit to the transfer unit where the developer is transferred to the recording medium, based on a consequence measured by the transfer current measuring unit, a recording medium width in a widthwise direction in association with the kind of the recording medium, the electrical character information, and a resistance value of the resistor, to precisely adjust a secondary transfer current value.

主权项

1. An image forming apparatus comprising:
an image forming unit; an image carrier carrying on a surface thereof a developer image formed by the image forming unit; a transfer unit for transferring the developer image carried on the image carrier to a recording medium; a voltage supplying unit for supplying a transfer voltage to the transfer unit; a transfer current measuring unit for measuring a transfer current value at a time that a prescribed voltage is applied from the voltage supplying unit to the transfer unit in a state that no recording medium exists in the transfer unit; a resistor serially coupled between the transfer current measuring unit and the transfer unit; a memory unit for storing electrical character information of the recording medium; a controller for controlling the transfer voltage supplied from the voltage supplying unit to the transfer unit where the developer is transferred to the recording medium, based on a consequence measured by the transfer current measuring unit, a recording medium width in a widthwise direction in association with the kind of the recording medium, the electrical character information of the recording medium, and a resistance value of the resistor; and a width detection unit for detecting the recording medium width, the width detection unit sequentially detecting the recording medium width changing in a sheet when the recording medium is conveyed, wherein the transfer voltage is determined based on the recording medium width sequentially changing.