| 摘要 |
Apparatus is disclosed for determining the degree of stiffness of a sheet, for example a banknote, the stiffness being indicative of the condition of the banknote. The banknote (4) is drawn around a bobbin-shaped drum (1) by means of a pair of belts (2, 3) which grip a central portion of the banknote. The inner belt (2) drives or is driven by the central portion of the drum (1). The concave shape of the drum (1) imparts a curvature to the banknote in an axial plane, while the banknote is simultaneously curved in an orthogonal plane as it is wrapped around the drum. As the banknote passes around the drum it emits an audible noise which is picked up by a microphone (5). The amplitude of the microphone signal (7) is proportional to the crispness of the banknote and is indicative of the age of the banknote. |
