초록 ▼

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

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.

대표청구항 ▼

In apparatus for detecting defects in webs or sheets, and having means defining a flow path for the web or for the sheets to be inspected, the combination of: an ultrasonic transmitter arranged to direct ultrasonic energy towards the flow path in an inspection area; an ultrasonic receiver directed t

In apparatus for detecting defects in webs or sheets, and having means defining a flow path for the web or for the sheets to be inspected, the combination of: an ultrasonic transmitter arranged to direct ultrasonic energy towards the flow path in an inspection area; an ultrasonic receiver directed to receive ultrasonic energy from the inspection area; and signal analysing means (FIG. 7) responsive to the output of the receiver; the transmitter directing the ultrasonic energy towards the inspection area as a continuous wave and the signal analysing means providing an output signal in response to changes in the output of the receiver during the passage of the web or sheet indicative of a defect in the inspected web or sheet; and wherein the receiver includes means defining in the inspection area a flow path which is convex in the longitudinal direction of the flow path, whereby the sheet or web is caused to assume a convex bend in the area in which the ultrasonic energy impinges upon it.