Patent ID: 7533981

Claim:
An image-forming apparatus, comprising: a first light-emitting element to emit light to a print medium at a first location; a second light-emitting element to emit light to the print medium at a second location; a voltage-supplying unit to apply an input voltage to the respective first and second light-emitting elements, wherein the first and second light-emitting elements are configured to emit a light level corresponding to the applied input voltage; a light-receiving element installed along an optical axis of total reflection light emitted from the first light-emitting element and reflected from a surface of the print medium; and a control unit to control the first and second light-emitting elements to alternately emit light to decide a print medium material based on a reflection amount of light received by the light-receiving element, and to establish print conditions adapted to the print medium, wherein the control unit comprises a function to decide that the print medium is made of a low ink-absorbing material having a large surface friction force if a reflection amount of light emitted from the first light-emitting element to the print medium and received by the light-receiving element, is larger than a reflection amount of light emitted from the second light-emitting element to the print medium and received by the light-receiving element.