Patent ID: 6501087
Filing Date: 2002-12-31
Classification: G07D

Abstract:
An image reading apparatus having a multiple wavelengths light sources comprisinga line shaped, two-wavelength transmitting LED array for transmitting light; a line shaped light emitting and photodetecting part comprising a photodetector array and a two-wavelength LED array for reflecting light disposed in opposition such that a scanned medium passes between the two-wavelength transmitting LED array and light emitting and photodetecting part, said two-wavelength reflecting LED array emitting light of different wavelengths; a storage time control circuit disposed in a signal processing circuit of the photodetector array; and a control means for controlling light emission by the two-wavelength transmitting LED array and the two-wavelength reflecting LED array, so that one wavelength LEDs in one of the two LED arrays are lit at one time, thereby controlling reading by the photodetectors, and controlling the storage time control circuit; wherein variations in wavelength detection sensitivity and light quantity with different read media are adjusted by means of the storage time of the storage time control circuit.