Image forming apparatus with a controller to control an alternating transfer bias

摘要

An image forming apparatus includes an image bearer; a transfer device; a transfer bias power source; and a controller to control the transfer bias power source. The transfer bias power source outputs the voltage that alternates between a transfer-directional voltage and a return-directional voltage. The transfer-directional voltage having a polarity transfers the toner image from a side of the image bearer to a side of the recording medium. The return-directional voltage has an opposite polarity to the polarity of the transfer-directional voltage. The controller reduces a frequency of the output voltage as a value of a ratio of A to B decreases while changing the value of the ratio of A to B. In this case, A is a time period of application of the return-directional voltage within one cycle of the output voltage, and B is a time period of the one cycle of the output voltage.

主权项

1. An image forming apparatus, comprising:
an image bearer configured to bear a toner image; a transfer device configured to contact the image bearer to form a transfer nip; a transfer bias power source configured to output an output voltage to transfer the toner image from the image bearer onto a recording medium in the transfer nip; and a controller configured to control the transfer bias power source, wherein the transfer bias power source is configured to output the output voltage that alternates between a transfer-directional voltage and a return-directional voltage, to transfer the toner image from the image bearer to the recording medium, the transfer-directional voltage having a polarity to transfer the toner image from the image bearer to the recording medium and the return-directional voltage having an opposite polarity to the polarity of the transfer-directional voltage, and wherein the controller is configured to reduce a frequency of the output voltage as a ratio of A to B decreases, where A is a time period of application of the return-directional voltage within one cycle of the output voltage, and B is a time period of the one cycle of the output voltage.