Patent US3679972A successfully refreshed from Google Patents.
US3679972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Micrometer thickness gage
Assignee: Lion Precision Corp
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Filing: 1971-04-26
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Granted: 1972-07-25
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Expires: 1991-04-26
Abstract
Abstract A gage for measuring the deviation in thickness of sheet material by measuring the sum of the capacitances between a top electrode and the upper surface of the sheet and a lower electrode and the bottom surface of the sheet. The gage is calibrated with a precise calibration sheet of known thickness, by adjusting the vertical position of the upper electrode to produce a null output on a capacitance bridge. For measuring, the upper electrode, adjustably mounted on a precise micrometer screw, is then adjusted by a distance precisely equal to the difference between the calibration sheet thickness and the target thickness of the material to be measured.
Inventors
- 👤 Louis Michelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:14
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/02; G01B7/06; G01B7/08; G01B7/087
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
295 words
A gage for measuring the deviation in thickness of electrically conductive sheet material from a target value of thickness comprising: first and second spaced apart confronting electrodes; a calibration sheet formed of electrically conductive material and having a precisely determined thickness; positioning means for positioning said first and second electrodes in a first position wherein said calibration sheet is interposed between said electrodes and for positioning said electrodes in a second position wherein said electrically conductive sheet to be measured is placed between said first and second electrodes; a null type capacitance measuring circuit connected to said first and second electrodes and to the sheet material positioned between said electrodes, said capacitance measuring circuit providing an output signal indicating the deviation from a nominal value of the variations in the sum of the capacitances formed between said first electrode and the surface adjacent to it of the sheet material positioned between the electrodes, and the capacitance formed between said second electrode and the surface adjacent to it of the sheet positioned between the electrodes; adjusting means for precisely adjusting the spacing between said electrodes; said adjusting means having a predetermined calibration spacing with said calibration sheet interposed, said adjusting means including means for changing said spacing for measurement of the sheet material by a distance precisely equal to the difference between the thickness of said calibration sheet and the target value of thickness of said material; and means for setting the nominal value of said capacitance measuring circuit to correspond to the sum of the capacitances with said electrodes at said predetermined calibration setting and said calibration sheet interposed therebetween, whereby in said second position the output signal from said capacitance measuring circuit represents deviations in thickness of said sheet material from said target value.
Claim 2
Dependent Claim
295 words
A gage for measuring the deviation in thickness of electrically conductive sheet material from a target value of thickness comprising: first and second spaced apart confronting electrodes; a calibration sheet formed of electrically conductive material and having a precisely determined thickness; positioning means for positioning said first and second electrodes in a first position wherein said calibration sheet is interposed between said electrodes and for positioning said electrodes in a second position wherein said electrically conductive sheet to be measured is placed between said first and second electrodes; a null type capacitance measuring circuit connected to said first and second electrodes and to the sheet material positioned between said electrodes, said capacitance measuring circuit providing an output signal indicating the deviation from a nominal value of the variations in the sum of the capacitances formed between said first electrode and the surface adjacent to it of the sheet material positioned between the electrodes, and the capacitance formed between said second electrode and the surface adjacent to it of the sheet positioned between the electrodes; adjusting means for precisely adjusting the spacing between said electrodes; said adjusting means having a predetermined calibration spacing with said calibration sheet interposed, said adjusting means including means for changing said spacing for measurement of the sheet material by a distance precisely equal to the difference between the thickness of said calibration sheet and the target value of thickness of said material; and means for setting the nominal value of said capacitance measuring circuit to correspond to the sum of the capacitances with said electrodes at said predetermined calibration setting and said calibration sheet interposed therebetween, whereby in said second position the output signal from said capacitance measuring circuit represents deviations in thickness of said sheet material from said target value.
Claim 3
Dependent Claim
47 words
A gage in accordance with claim 1 and further including a frame member, said first electrode being mounted in fixed position on said frame member and said second electrode being mounted on said frame member by said adjusting means, said adjusting mean comprising a precision micrometer screw.
Claim 4
Dependent Claim
44 words
A gage in accordance with claim 2 wherein said frame is mounted for sliding movement with respect to said sheet material and said calibration sheet, and wherein said positioning means includes means for sliding said frame from said first position to said second position.
Claim 5
Dependent Claim
79 words
A gage in accordance with claim 2, said adjusting means further including a stepping motor and a servo positioning unit, having means for entering said target thickness therein, said stepping motor being mechanically coupled to said precision micrometer screw to rotate said screw in precise increments as said stepping motor is stepped, said servo position unit being coupled to said stepping motor to actuate said stepping motor according to the value of target thickness entered into said servo unit.
Claim 6
Independent Claim
181 words
The method of measuring the deviation in thickness of an electrically conductive sheet material from a target value of thickness utilizing a capacitance thickness gage having a pair of spaced confronting electrodes comprising the steps of: spacing said electrodes with a predetermined distance between them; inserting a calibration sheet formed of electrically conductive material and having a precisely determined thickness between said electrodes; connecting a null type capacitance measuring means to said first and second electrodes such that the output signal from said capacitance measuring means varies with variation in the sum of the capacitances formed between said first electrode and the adjacent surface of the calibration sheet and the capacitance formed between said second electrode and the adjacent surface to it of the calibration sheet and nulling the capacitance measuring circuit to provide a zero output signal under these conditions; removing the calibration sheet; and adjusting the spacing between said electrodes by an amount precisely equal to the difference between the thickness of said calibration sheet and the target value of thickness and inserting the sheet material between said electrodes.
Claim 7
Independent Claim
181 words
The method of measuring the deviation in thickness of an electrically conductive sheet material from a target value of thickness utilizing a capacitance thickness gage having a pair of spaced confronting electrodes comprising the steps of: spacing said electrodes with a predetermined distance between them; inserting a calibration sheet formed of electrically conductive material and having a precisely determined thickness between said electrodes; connecting a null type capacitance measuring means to said first and second electrodes such that the output signal from said capacitance measuring means varies with variation in the sum of the capacitances formed between said first electrode and the adjacent surface of the calibration sheet and the capacitance formed between said second electrode and the adjacent surface to it of the calibration sheet and nulling the capacitance measuring circuit to provide a zero output signal under these conditions; removing the calibration sheet; and adjusting the spacing between said electrodes by an amount precisely equal to the difference between the thickness of said calibration sheet and the target value of thickness and inserting the sheet material between said electrodes.
References Cited (Backward Citations)
US1924087A
Cited
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 |