Patent ID: 6728008
Filing Date: 2004-04-27
Classification: H04N

Abstract:
A method of diagnosing an optical device having a plurality of photoelectric elements that are arranged in a scanning line in a main scanning direction, for receiving light reflected from a document and outputting a signal corresponding to an amount of light received, comprising:a first step of reading, along a predetermined scanning line, a figure that consists of a first straight line perpendicular to the main scanning direction, second and third straight lines parallel to each other and intersect the first straight line at an acute angle, using the photoelectric elements of the optical device opposed to the figure with a predetermined space interposed therebetween; a second step of detecting respective positions of first, second and third intersections between the scanning line and each of the first, second and third straight lines of the figure, and also detecting output levels of signals corresponding to the intersections, on the basis of signals output when the figure has been read along the scanning line; and a third step of comparing the detected positions of the intersections with positions of respective predetermined points which are to detect the intersections, and the detected output levels of the signals corresponding to the intersections with respective predetermined output levels of signals corresponding to respective predetermined points, thereby detecting an error due to an attachment position of the optical device.