Patent ID: 8558205
Filing Date: 2013-10-15
Classification: G01N,G06K,G07D

Abstract:
1. A light detection device comprising: a first sensor which detects fluorescence from a first detection position on a conveyor path along which a sheet is conveyed; a second sensor which detects afterglow from a second detection position on the conveyor path along which the sheet is conveyed; a lighting device which applies excitation light over a range including the first detection position and not including the second detection position; a first reference plate which emits reference light toward the first sensor, the first reference plate including fluorescent material which emits fluorescence by being excited by the lighting device; a second reference plate which emits reference light toward the second sensor when the sheet is present at the second detection position, the reference light not influencing a result of detection by the second sensor; and a correction controller which corrects a result of detection by the first sensor based on the reference light emitted by the first reference plate and detected by the first sensor and to correct a result of detection by the second sensor based on the reference light emitted by the second reference plate and detected by the second sensor.