FLUORESCENT INK AND RECORDED INFORMATION READING APPARATUS

摘要

PROBLEM TO BE SOLVED: To enable both information recoreded with an invisible or hardly visible fluorescent ink and information recorded with a common colored ink to be read. SOLUTION: A fluorescent ink which contains a fluorescent substance having absorption wave lepgths of 600-700 nm and emitting fluorescent light in the range of 600-900 nm and another fluorescent substance having absorption wavelengths of 400 nm or lower and emitting fluorescent light in the range of 600-700 nm and which emits fluorescent light by the excitation with light of wavelengths in the range of visible ray spectrum is used for printing a bar code on a label 1. The label 1 is irradiated with visible light of wavelengths of 600-700 nm from an LED light sourece 12 as exciting light. Light from the label is caused to pass through a filter of a filtering device 15 for cutting exciting light, thus causing a CCD sensor 16 to accept only light emitted by the fluorescent ink and to read the bar code. When a bar code printed with a colored ink is read from a label, a filter for cutting light emitted by a fluorescent ink is used.