EP0208214A2
Expired / Lapsed
EP
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A metal detector
Assignee: Goring Kerr PLC
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Filing: 1986-06-27
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Granted: —
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Expires: 2006-06-27
Abstract
Abstract In a metal detector, such as may be used in a bakery, an adjustable phase shifter is provided to adjust the detectors of different products. The adjustable phase shifter is controlled electronically from the output signal so that the arrangement is self-adjusting.
Inventors
- 👤 Bruce Goring Kerr
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 21:31
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/08; G01V3/10; G01V3/104; G01V3/105; G01V3/107
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
113 words
A detector comprising a first energised coil through the field of which an item to be inspected is passed, a second coil arrangement within the field of the first coil which produces an output signal, part of the signal energising the first coil and the output signal of the second coil being fed to the inputs of two phase detectors, one input of a phase detector being associated with a 90° phase shifter and one input of a phase detector being associated with an adjustable phase shifter, the output of at least one phase detector being monitored to produce a control signal, the control signal being used to adjust said adjustable phase shifter.
Claim 2
Dependent Claim
113 words
A detector comprising a first energised coil through the field of which an item to be inspected is passed, a second coil arrangement within the field of the first coil which produces an output signal, part of the signal energising the first coil and the output signal of the second coil being fed to the inputs of two phase detectors, one input of a phase detector being associated with a 90° phase shifter and one input of a phase detector being associated with an adjustable phase shifter, the output of at least one phase detector being monitored to produce a control signal, the control signal being used to adjust said adjustable phase shifter.
Claim 3
Dependent Claim
25 words
A detector according to claim 1 wherein the 90° phase shifter and the adjustable phase shifter are associated with one input of one phase detector.
Claim 4
Dependent Claim
37 words
A detector according to claim 1 or claim 2 wherein the voltage of the output of one phase detector is monitored by a voltage monitor to produce said control signal in response to variations in said voltage.
Claim 5
Dependent Claim
40 words
A detector according to claim 3 wherein the output of the other phase detector is fed to a polarity detector which provides signals to the voltage monitor indicative of the polarity of the input to the said other polarity detector.
Claim 6
Dependent Claim
57 words
A detector according to claim 4 wherein the voltage monitor includes signal storing means, and switches controlled by the polarity sensor so that when one polarity is sensed the signal storing means supplied with said voltage in one way, and when another polarity is sensed the signal storing means are supplied with said voltage in another way.
Claim 7
Dependent Claim
68 words
A detector according to claim 5 wherein the signal storing means comprise a first capacitor which is charged with the output of said phase detector when one polarity is sensed, and which is charged with the inverted output of that phase detector when the other polarity is sensed, there being a second capacitor which is charged with the output of said phase detector when no polarity is sensed.
Claim 8
Dependent Claim
48 words
A detector according to claim 5 wherein the signal storing means comprise two capacitors, one of which is charged with the output of the said phase detector when one polarity is sensed, the other being charged with the output of said phase-detector when the other polarity is sensed.
Claim 9
Dependent Claim
30 words
A detector according to claim 6 or 7 wherein the capacitors are connected to a differential amplifier, the output of which provides the control signal for the adjustable phase shifter.
Claim 10
Dependent Claim
27 words
A detector according to any one of claims 3 to 8 wherein a signal delay device is present between the voltage monitor and the adjustable phase shifter.
Claim 11
Dependent Claim
56 words
A detector according to claim 1 or 2 wherein the outputs of the first phase detector and the second phase detector are fed to the inputs of a third phase detector, the output of the third phase detector being connected, by means of an RC delay network to the control terminal of said adjustable phase shifter.
Claim 12
Dependent Claim
30 words
A detector according to claim 10 wherein means are provided to reduce the time constant of the RC network to enable a rapid setting of the detector to be obtained.
Claim 13
Dependent Claim
18 words
A detector according to claim 11 wherein said means to shorten the RC time constant comprise switchable means.
References Cited (Backward Citations)
No citation records indexed.
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