Patent ID: 8565624

Claim:
An image forming apparatus comprising: a process cartridge comprising: a developer bearing member configured to bear and convey a developer and supply it to an image bearing member, a developer container containing an electrically-conductive member therein, and including a first chamber for containing the developer and a second chamber where the developer bearing member is disposed, the second chamber being in communication with the first chamber through an opening for supplying the developer transferred from the first chamber through the opening to the developer bearing member, and a seal member configured to seal and close the opening until a start of a use and be removed from the opening at the time of the start of the use, the seal member including an electrically-conductive layer positioned at the opening, the electrically-conductive layer and the developer bearing member being electrically conducting when the opening is sealed and closed; a support member configured to support the process cartridge in such a manner that the process cartridge is removably loadable thereon; a voltage application unit configured to apply bias voltage containing an alternating-current component to the developer bearing member; a signal generation unit to, upon an application of the bias voltage to the developer bearing member by the voltage application unit, output an electrical signal according to electrostatic capacity between the seal member and the electrically-conductive member if the seal member seals and closes the opening, and output an electric signal according to electrostatic capacity between the developer bearing member and the electrically-conductive member if the seal member is removed from the opening; and a determination unit configured to determine that the process cartridge is not loaded if the signal generation unit outputs the electric signal corresponding to first reference electrostatic capacity or less, and determine that the seal member is not removed if the signal generation unit outputs the electric signal corresponding to second reference electrostatic capacity or more, the second reference electrostatic capacity being greater than the first reference electrostatic capacity.