IMAGE FORMING APPARATUS

摘要

An image forming apparatus includes an image bearer, a transfer device contacting the image bearer to form a transfer portion, a transfer bias power source, and a controller. A ratio of a time period of application of the opposite-directional bias to a total time period of one cycle of the AC component of the superimposed bias is greater than 50%. A ratio of a value of the DC component of the superimposed bias output within a region ranging from a leading end of the recording medium to a predetermined length to a value of the DC component of the superimposed bias output outside the region is greater than a ratio of a value of the AC component of the superimposed bias output within the region to a value of the AC component of the superimposed bias output outside the region.

主权项

1. An image forming apparatus, comprising:
an image bearer to bear a toner image; a transfer device contacting the image bearer to form a transfer portion; and a transfer bias power source to output a transfer bias to transfer the toner image from the image bearer to a recording medium at the transfer portion, the transfer bias being a superimposed bias including a direct current (DC) component and an alternating current (AC) component that cyclically alternates between a transfer-directional bias to transfer the toner from the image bearer to the recording medium and an opposite-directional bias in an opposite direction of the transfer direction, a controller to control the transfer bias power source to output the transfer bias, wherein a ratio of a time period of application of the opposite-directional bias to a total time period of one cycle of the AC component of the superimposed bias is greater than 50%, wherein a ratio of a value of the DC component of the superimposed bias output within a region ranging from a leading end of the recording medium to a predetermined length to a value of the DC component of the superimposed bias output outside the region is greater than a ratio of a value of the AC component of the superimposed bias output within the region to a value of the AC component of the superimposed bias output outside the region.