Patent ID: 7496301

Claim:
An image-forming device, comprising: a developer-accommodating section that accommodates a developer, the developer-accommodating section defining a plurality of detection light transmitting points through which a detection light is transmitted to detect an amount of developer accommodated in the developer-accommodating section; and a residual developer detecting unit that has a light-emitting unit that irradiates a detection light through one of the detection light transmitting points and a light-receiving unit that receives the detection light that has passed through the subject one detection light transmitting point, wherein the developer-accommodating section is movably disposed, and the detection light transmitting points are switched through movement of the developer-accommodating section, the detection light transmitting points including at least a first detection light transmitting point and a second detection light transmitting point that is spaced from the first detection light transmitting point, wherein the image-forming device further comprises a determining unit that determines the amount of developer in the developer-accommodating section, and wherein the determining unit includes: a first control unit that controls the light-emitting unit to irradiate the detection light through the first detection light transmitting point, and that determines the amount of developer in the developer-accommodating section based on a detection result indicating whether the light-receiving unit has received the detection light that has passed through the first detection light transmitting point; a moving unit that selectively moves the developer-accommodating section, dependently on a determining result of the first control unit, to switch the detection light transmitting points, thereby enabling the light-emitting unit to irradiate the detection light through the second detection light transmitting point; and a second control unit that controls the light-emitting unit to irradiate the detection light through the second detection light transmitting point, and that determines the amount of developer in the developer-accommodating section based on a detection result indicating whether the light-receiving unit has received the detection light that has passed through the second detection light transmitting point.