| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately detect a short circuit abnormality of an LED at a low cost. <P>SOLUTION: An image reader includes: a light emission circuit which turns on a plurality of light emitting elements connected in series to illuminate a document; a drive circuit for driving the plurality of light emission circuits connected in parallel; a white reference plate arranged in a position such that the document can be read; and an abnormality detecting part which instructs the drive circuit to drive all the light emission circuits and illuminate the white reference plate, and determines that a short circuit abnormality exists in the light emitting element if a quantity of the light reflected from the white reference plate is less than a predetermined light quantity. Each of the light emitting elements is arrayed alternately along a main scanning direction of the document for each light emission circuit. The abnormality detecting part, upon determination of occurrence of the short circuit abnormality, drives the light emission circuits one by one to identify a position in the main scanning direction of the document at which the light quantity reflected from the white reference plate is less than the predetermined light quantity, and determines that the short circuit abnormality exists in the light emitting element arrayed at the identified position. <P>COPYRIGHT: (C)2012,JPO&INPIT |
