Patent ID: 8081888

Claim:
An image forming device, comprising: a container configured to accommodate toner; a light emitting unit configured to emit light to be transmitted through the container; a light receiving unit configured to receive the light transmitted through the container; a computer; and one or more non-transitory computer readable media having executable instructions stored thereon that, when executed by the computer, cause the computer to function as: an efficiency determining unit configured to determine a light receiving efficiency based on a light intensity of the light received by the light receiving unit; an execution amount determining unit configured to determine an execution amount of image forming operations that represents an accumulated amount of image forming operations executed since first use of the container; a correction coefficient determining unit configured to determine a correction coefficient based on the execution amount of image forming operations determined by the execution amount determining unit; an efficiency modifying unit configured to modify the light receiving efficiency determined by the efficiency determining unit with the correction coefficient determined by the correction coefficient determining unit; and an estimating unit configured to estimate an amount of the toner remaining in the container based on the light receiving efficiency modified by the efficiency modifying unit.