The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 28, 1992
Filed:
Jul. 12, 1990
Anthony R Burge, Hants, GB;
Michael Potter, Hants, GB;
De la Rue Systems Ltd., , GB;
Abstract
Holes, tears and missing portions in a sheet, such as a banknote, are detected. The sheet is irradiated with radiation so that the radiation passes through the sheet with a relatively low degree of attenuation in areas where holes, tears and missing portions do not exist and with a relatively high degree of attenuation in areas where holes, tears and missing portions exist. The attenuated radiation is retroreflective back through the sheet and is then received by appropriate photodetectors. Since the sheet is relatively opaque and the radiation passes through the same points in the sheet twice, the contrast between the received radiation having passed through the holes, tears and missing portions and the received radiation passing through the relatively opaque sheet is very high making it simple to differentiate between those areas and thereby to positively detect holes, tears and missing portions in the sheet.