Detecting unit and image forming apparatus

A detecting unit for an image forming apparatus configured to form a toner image on an image carrier, the detecting unit comprising:

• a first sensor including a first substrate, the first sensor being disposed on a first side in a particular direction of the detecting unit, the particular direction corresponding to a width direction of the image carrier;
• a second sensor including a second substrate, the second sensor being disposed on a second side, which is opposite to the first side, in the particular direction;
• a first cable harness including a plurality of first wires corresponding to the first sensor;
• and
• a second cable harness including:
• a plurality of second wires corresponding to the first sensor;
• and
• a plurality of wires corresponding to the second sensor, wherein:
• the first sensor is configured to detect a mark image formed in a first area of the image carrier by emitting a first light to the first area and receiving the first light reflected from the first area, the first area being located on a first side in the width direction of the image carrier;
• the second sensor is configured to detect a mark image formed in a second area of the image carrier by emitting a second light to the second area and receiving the second light reflected from the second area, the second area being located on a second side, opposite to the first side, in the width direction of the image carrier;
• the first cable harness has a first end and a second end opposite to each other, the first end of the first cable harness being connected to the first substrate, and the second end of the first cable harness being connected to the second substrate;
• the second cable harness has a first end and a second end opposite to each other, the first end of the second cable harness being connected to the second substrate, and the second end of the second cable harness being connectable to a controller of the image forming apparatus;
• and
• the second substrate includes a plurality of relay wiring patterns connecting the plurality of first wires and the plurality of second wires.