Patent ID: 7437099

Claim:
An image forming apparatus comprising: an image forming unit that forms an image on a recording medium, the image forming unit including an image bearing member; a conveying unit that conveys the recording medium at a conveying speed; and a driving unit that rotates the image bearing member, the driving unit including: a motor having a rotation shaft and generating a rotational force for rotating the rotation shaft at a rotational speed; a first gear that rotates integrally with the rotation shaft, the first gear having a predetermined number of teeth; and a second gear engaged with the first gear; wherein the driving unit is configured in such a manner that an engagement noise frequency is larger than an image-quality assurance frequency and that the engagement noise frequency is less than or equal to an upper limit frequency of a one-third octave band frequency range including the image-quality assurance frequency; and wherein the image-quality assurance frequency is defined as a frequency obtained by multiplying the conveying speed of the recording medium by a value of 1.6, and the engagement noise frequency is defined as a frequency obtained by multiplying the predetermined number of teeth of the first gear by the rotational speed of the motor, when a unit of the conveying speed of the recording medium is millimeters per second, a unit of the value of 1.6 is cycles per millimeter, and a unit of the rotational speed of the motor is revolutions per second.