Patent ID: 9075350
Filing Date: 2015-07-07
Classification: G03G

Abstract:
1. An image forming apparatus, comprising: an image bearing member to bear a toner image on a surface thereof; a transfer member disposed opposite the image bearing member to contact the surface of the image bearing member to form a transfer nip; a power source to output a voltage to transfer the toner image from the image bearing member onto a recording medium interposed in the transfer nip, the voltage including a first voltage in a transfer direction in which the toner image is transferred from the image bearing member to the recording medium and a second voltage having a polarity opposite that of the first voltage, and the first voltage and the second voltage alternating upon transfer of the toner image from the image bearing member to the recording medium; and a controller operatively connected to the power source to control the power source, wherein a time-averaged value of the voltage has a polarity in the transfer direction, and an absolute value of the time-averaged value of the voltage is greater than a midpoint value of the voltage, the midpoint value of the voltage being an intermediate value between a maximum value and a minimum value of the voltage and the time-averaged value of the voltage being a value of an integral value of an alternating waveform of the voltage over one cycle divided by a length of said one cycle, and wherein as a roughness of the recording medium increases, the controller controls the power source to reduce a duty ratio expressed by A/(A+B), where A is an area of the alternating waveform of the voltage in said one cycle in a return direction opposite the transfer direction relative to the midpoint value of the voltage and B is an area of the alternating waveform of the voltage in the transfer direction relative to the midpoint value of the voltage.