Patent ID: 8620174

Claim:
An image forming apparatus comprising: a toner density detection unit configured to detect toner density; a cleaning member configured to linearly reciprocate to clean a detection surface of the toner density detection unit; a motor having a rotational shaft; and a motion conversion unit configured to convert a rotation of the rotational shaft to a linear reciprocal movement of the cleaning member; wherein the motion conversion unit comprises: a worm gear fixed to the rotational shaft; a cam having a shape configured to cause the cleaning member to perform one reciprocal movement at each rotation of the cam, the cam including a cam groove and external gear teeth engaging with the worm gear directly or indirectly; a transmission arm member including a fulcrum, a first arm portion having a convex portion engaging with the cam groove, and a second arm portion having an engaging portion, the transmission arm member performing a pendular movement about the fulcrum; and a horizontal moving member reciprocatable in a horizontal direction and having a coupling portion, with which the engaging portion engages; wherein the horizontal moving member includes a covering portion that covers the detection surface of the toner density detection unit from upward, following reciprocal movement of the horizontal moving member, and an open portion that exposes the detection surface from upward, and wherein the cleaning member is fixed to a lower side of the covering portion of the horizontal moving member.