Patent ID: 7457553

Claim:
An image-forming device for forming images using a developing agent, said image-forming device comprising: a supporting member having a surface capable of supporting said developing agent; a supporting member driving unit capable of driving so as to move said surface of said supporting member; a density sensor capable of generating a signal according to the density of said developing agent on said surface, disposed facing said surface of said supporting member; a blocking member, disposed between said density sensor and said supporting member, so as to be able to be positioned in a blocked state capable of blocking the density sensor relative to said supporting member and an exposed state capable of exposing said density sensor to said supporting member; and a blocking member driving unit structured so as to change the state of said blocking member between said blocked state and said exposed state through transmission of a driving force from said supporting member driving unit, wherein said blocking member is structured from a disk having a notch, and wherein said blocking member driving unit is structured so as to rotate said disk.