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US3679968A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and device for measuring the thickness of a metal deposit on an insulating support
Assignee: Individual
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Filing: 1970-03-16
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Granted: 1972-07-25
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Expires: 1990-03-16
Abstract
Abstract Plastic film is drawn from a spool and passes around a drum in a vacuum chamber in such a way that the film is exposed to metal vapor which is deposited thereon in thickness ranging from 50 angstroms to several microns. The metallized film then passes around guide rollers and is wound on a reel. One of the guide rollers comprises a novel hermetically sealed shell of electrical insulating material containing novel detectors which are responsive to the thickness of the metal coating on the film. Such detectors consist of coreless induction coils, each constituting the tuning element of a unique stabilized oscillating circuit, the voltage of which is a very accurate measure of the relative thickness of the metal coating on the film by virtue of the eddy currents induced therein.
Inventors
- 👤 Jean Claude Commercon
- 👤 Guy Berthier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:51
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/02; G01B7/06; G01B7/10; G01B7/105
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
351 words
Apparatus for measuring variations of the thickness of an electrically conductive layer on a continuously moving film, said apparatus comprising: an oscillating circuit including a variable-gain amplifier with a relatively low output impedance and having an output connected to a self-induction coil and a tuning capacitor connected in series circuit relationship, said coil and said capacitor forming the tuning elements of said oscillating circuit, said self-induction coil being disposed with respect to said conductive layer on said film such that the current which flows in said self-induction coil develops eddy currents withing the conductive layer, a vacuum enclosure, a freely rotating roller of electrically insulating material within said enclosure, said coil being arranged in said vacuum enclosure within said freely rotating roller, said roller being in contact with the film after deposition of the conductive layer thereon, A feed-back loop in said oscillating circuit connected to the junction between said coil and said capacitor and the input of said variable gain amplifier and including a second capacitor returned to the input of said variable gain amplifier for sustaining the oscillations of said oscillating circuit, a control circuit including a stable-gain amplifier-rectifier connected to the output of said variable gain amplifier, a stabilized voltage source, a difference voltage detector connected to the output of said stable-gain amplifier-rectifier and to said stabilized voltage source, the output of said detector being connected to said variable-gain amplifier in order to continuously modify the gain thereof and to maintain its output voltage constant, a high input impedance amplifier means connected to said feedback loop, indicating means connected to said amplifier means for indicatIng the output voltage variations of said loop, said output variations being representative of the relative amount of said eddy currents induced in the conductive layer by said coil, the voltage indicated by said indicating means being a measure of the thickness of the conductive layer on said film, regulating means connected to the output of said indicating means, and means connected to said regulating means for adjusting the rate of movement of said film in response to the output of said indicating means.
Claim 2
Dependent Claim
351 words
Apparatus for measuring variations of the thickness of an electrically conductive layer on a continuously moving film, said apparatus comprising: an oscillating circuit including a variable-gain amplifier with a relatively low output impedance and having an output connected to a self-induction coil and a tuning capacitor connected in series circuit relationship, said coil and said capacitor forming the tuning elements of said oscillating circuit, said self-induction coil being disposed with respect to said conductive layer on said film such that the current which flows in said self-induction coil develops eddy currents withing the conductive layer, a vacuum enclosure, a freely rotating roller of electrically insulating material within said enclosure, said coil being arranged in said vacuum enclosure within said freely rotating roller, said roller being in contact with the film after deposition of the conductive layer thereon, A feed-back loop in said oscillating circuit connected to the junction between said coil and said capacitor and the input of said variable gain amplifier and including a second capacitor returned to the input of said variable gain amplifier for sustaining the oscillations of said oscillating circuit, a control circuit including a stable-gain amplifier-rectifier connected to the output of said variable gain amplifier, a stabilized voltage source, a difference voltage detector connected to the output of said stable-gain amplifier-rectifier and to said stabilized voltage source, the output of said detector being connected to said variable-gain amplifier in order to continuously modify the gain thereof and to maintain its output voltage constant, a high input impedance amplifier means connected to said feedback loop, indicating means connected to said amplifier means for indicatIng the output voltage variations of said loop, said output variations being representative of the relative amount of said eddy currents induced in the conductive layer by said coil, the voltage indicated by said indicating means being a measure of the thickness of the conductive layer on said film, regulating means connected to the output of said indicating means, and means connected to said regulating means for adjusting the rate of movement of said film in response to the output of said indicating means.
Claim 3
Dependent Claim
24 words
Apparatus according to claim 2, whereas said indicating means comprises a graphic recording device connected to said amplifier means for recording said voltage variations.
Claim 4
Dependent Claim
31 words
Apparatus according to claim 1, an alarm device whereas said indicating means further comprises for producing an alarm signal when said thickness connected to said amplifier means detected exceeds predetermined limits.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |