Patent ID: 7181148

Claim:
A detection device, used in an image forming apparatus, comprising: a light-emitting element which emits light towards a toner pattern formed on an image carrier; a first light-receiving element which detects the light reflected from the toner pattern; a second light-receiving element which detects the light reflected from the toner pattern in a fashion different from the first light-receiving element; and a control unit which calculates the amount of toner of the toner pattern based on the output values from the first and second light-receiving elements, and also calculates the position of the toner pattern based on the output value from the first light-receiving element, wherein said light-emitting element includes a polarizing plate, and said first light-receiving element includes a polarizing plate having a direction of polarization parallel to the polarizing plate of the light-emitting element, while the second light-receiving element includes a polarizing plate having a direction of polarization different from the polarizing plate of the light-emitting element.