Patent ID: 7614716

Claim:
A discriminating apparatus operable to discriminate a type of recording sheet, comprising: an irradiating device configured to irradiate light to a predetermined area of the recording sheet based on an input first pulse signal; a detecting device detecting a temperature of the predetermined area of the recording sheet simultaneously with irradiating of light by the irradiating device, and outputting the detected temperature as a second pulse signal; and a discriminating device discriminating the type of recording sheet based on the thermal conductivity of the recording sheet and an amount of reflected light, wherein the discriminating device obtains the thermal conductivity based on a phase difference between the first pulse signal and the second pulse signal and an amplitude of the second pulse signal, and wherein the discriminating device discriminates the recording sheet as a normal paper when the thermal conductivity is lower than a first value, discriminates the recording sheet as a glossy coated paper when the thermal conductivity is higher than the first value and the amount of reflected light is larger than a second value, and discriminates the recording sheet as a non-glossy coated paper when the thermal conductivity is higher than the first value and the amount of reflected light is smaller than the second value.