Sheet thickness detector, sheet conveyor, and image forming apparatus

A sheet thickness detector comprising:

• a conveyance roller pair including:
• a conveyance roller rotatable about a drive shaft to convey a sheet in a sheet conveyance direction;
• and
• a detection roller separately contactable with the conveyance roller to nip the sheet between the conveyance roller and the detection roller at an initial position;
• a pressing member to press the detection roller to the conveyance roller in a contact direction orthogonal to the sheet conveyance direction and an axial direction of the drive shaft;
• a separation mechanism to separate the detection roller from the conveyance roller in a separation direction opposite to the contact direction;
• and
• a displacement detector to detect a displacement of the detection roller in the separation direction from the initial position to detect a thickness of the sheet in response to a nip of the sheet by the conveyance roller pair,
• wherein the separation mechanism is decoupled from the detection roller in response to a detection of the thickness of the sheet.