Image reading device

An image reading device, comprising:

• a capacitance detection device comprising
• a first electrode and a second electrode at least partially facing each other with a conveyance path therebetween, the conveyance path extending along a conveyance direction in which a sheet-like detection object is conveyed;
• an oscillating circuit to form an electric field between the first electrode and the second electrode;
• a detection circuit to detect a change in capacitance between the first electrode and the second electrode;
• a first board including at least one of the oscillating circuit or the detection circuit;
• a second board including at least the other one of the oscillating circuit and the detection circuit;
• an insulative first plate arranged between the first electrode and the conveyance path;
• and
• an insulative second plate arranged between the second electrode and the conveyance path;
• a light source to irradiate the detection object with light;
• and
• an image reader to read an image with a reflection light from the light source reflected on the detection object or a transmitted light from the light source transmitted through the detection object, wherein
• the first electrode and the second electrode are arranged on an upstream side or a downstream side of the conveyance path in the conveyance direction with respect to an image reading position of the image reader, and
• the first board and the second board each have a main surface arranged in parallel to a direction perpendicular to the conveyance direction, and the first board is out of line with the second board in the conveyance direction.