Image sensor unit and image reader

摘要

An illumination device includes a light guide made of plastic, and a light source including a light emitting element whose dominant wavelength is a light emission wavelength in an infrared region, and identifies a banknote. White reference plates are provided at positions that are at opposite ends of a rod lens array and cover respective areas external to an image region across the banknote. A correction coefficient is acquired by calculation. The calculation is made by correcting an illuminance such that IR correction data is substantially identical to IR reference data preliminarily stored in a memory circuit in a signal processor on the basis of IR white reference data representing a white reference illuminance generated from light reflected from the white reference plates. The correction coefficient is used for correcting IR image data when the banknote is read.

主权项

1. An image sensor unit, comprising:
a light source; a light guide that guides light from the light source and linearly emits light to a subject to be illuminated; an image-forming element that forms an image of light from the illuminated subject on a photoelectric conversion element to generate image data; a memory circuit that stores reference data to be a reference illuminance of an image region across the illuminated subject; a white reference provided at positions that are at opposite ends of the image-forming element in a longitudinal direction and cover respective areas external to the image region across the illuminated subject; a white reference data generation circuit that reads light reflected from the white reference means by the photoelectric conversion element and for generating white reference data that represents a white reference illuminance; a correction data generation circuit that generates correction data that represents a white reference illuminance of the image region across the illuminated subject on the basis of the white reference data; a comparison circuit that calculates a correction coefficient from the correction data and the reference data; and a correction circuit that corrects the image data on the basis of the correction coefficient, wherein the light guide is made of a material having a region in which transmittance is not constant with respect to wavelength, and wherein the light source includes at least one of light emission wavelengths in the region of the light guide in which transmittance is not constant and light emission wavelengths in proximity to the region in which transmittance is not constant.