Apparatus for detecting the condition of a sheet or web
US4519249A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 27, 1983 |
| Grant date | May 28, 1985 |
| Priority date | — |
| Expiry date | Jun 27, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
For the detection of defects such as tears or fold lines in banknotes, for example, continuous wave ultrasonic energy is directed by a transmitter to a flow path for the notes and ultrasonic energy reflected from the notes or transmitted through tears or holes in the notes is converted by a receiver into an electric signal. A signal analyzing circuit is responsive to changes in the output of the receiver during the passage of the banknote. In the ultrasonic inspection area, the note may be passed over rollers with flared ends to cause a tear to open and allow the passage of ultrasonic energy. In a reflective system the note may be passed over a roller to cause one or both of the adjacent edges of a tear to leave the roller surface. The electric signal is analyzed for components indicative of a defect; for tear detection, a spike filter and a circuit for distinguishing tear signals from end-of-note signals may be used. For crinkle detection, the received signal may pass through a differentiator, an integrator and a threshold comparator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.