Patent US4914828A successfully refreshed from Google Patents.
US4914828A
Expired / Lapsed
US
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Surface inspection device and method
Assignee: PPG Industries Inc
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Filing: 1988-08-09
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Granted: 1990-04-10
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Expires: 2008-08-09
Abstract
Abstract A method and apparatus for measuring surface irregularities on articles such as curved automotive glass are provided wherein two contact points on a sensor head establish a chord at a segment of the surface and a probe measures the distance of the surface from the chord between the contact points, thereby permitting calculation of the local radius of curvature as the surface is scanned.
Inventors
- 👤 Robert J. Fiedor
- 👤 Aloysius W. Farabaugh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:20
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/28; G01B7/293; G01B7/34; G01B7/345
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
156 words
A method for measuring surfce irregularities on a curved surface of an article comprising: contacting the curved surface with two tips fixed on a sensor head thereby defining an arc segment on the surface between the two points of contact and a corresponding straight line chord between the two points of contact; contacting the curved surface with a probe between the two contact tips, the probe being free to reciprocate normal to the surface; generating a first signal proportional to the elevation of the probe contact point from the chord and processing the first signal to generate a second signal proportional to the radius of curvature of the arc segment; scanning the sensor head along a predetermined path with the tips and probe in contact with the article surface; and exhibiting a sequence of readings derived from a series of the second signals so as to indicate the degree of surface irregularity in the curved surface.
Claim 2
Independent Claim
156 words
A method for measuring surfce irregularities on a curved surface of an article comprising: contacting the curved surface with two tips fixed on a sensor head thereby defining an arc segment on the surface between the two points of contact and a corresponding straight line chord between the two points of contact; contacting the curved surface with a probe between the two contact tips, the probe being free to reciprocate normal to the surface; generating a first signal proportional to the elevation of the probe contact point from the chord and processing the first signal to generate a second signal proportional to the radius of curvature of the arc segment; scanning the sensor head along a predetermined path with the tips and probe in contact with the article surface; and exhibiting a sequence of readings derived from a series of the second signals so as to indicate the degree of surface irregularity in the curved surface.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein the probe elevation relative to the chord is measured by a transducer.
Claim 4
Dependent Claim
24 words
The method of claim 2 wherein the probe elevation is measured in a plane that includes the points of contact of the two tips.
Claim 5
Dependent Claim
24 words
The method of claim 3 wherein the probe elevation is measured midway between the two points of contact of the tips on the article.
Claim 6
Dependent Claim
44 words
The method of claim 1 wherein the surface of the article being measured has an overall curvature having a relatively large radius and the spacing of the contact tips is less than four inches so as to measure surface deviations of relatively small radii.
Claim 7
Dependent Claim
15 words
The method of claim 5 wherein the article being measured is a sheet of glass.
Claim 8
Dependent Claim
15 words
The method of claim 1 wherein the article being measured is a sheet of glass.
Claim 9
Dependent Claim
17 words
The method of claim 1 wherein the locus of the scan is in a mechanically determined plane.
Claim 10
Dependent Claim
24 words
The method of claim 1 wherein surface irregularities being measured cause the probe to be elevated from the chord no more than 0.005 inch.
Claim 11
Dependent Claim
24 words
The method of claim 1 wherein surface irregularities being measured cause the probe to be elevated from the chord no more than 0.001 inch.
Claim 12
Dependent Claim
29 words
The method of claim 1 wherein the readings indicating the degree of surface irregularity are compared with a predetermined standard so as to determine the acceptability of the article.
Claim 13
Dependent Claim
31 words
The method of claim 11 wherein a numerical value representing overall surface quality of the article is calculated from the readings and employed as the basis for comparison with the standard.
Claim 14
Dependent Claim
19 words
The method of claim 1, further including indexing the article in a predetermined location relative to the scanning path.
Claim 15
Dependent Claim
24 words
The method of claim 13, further comprising indexing and measuring the surface irregularities of a plurality of separate articles having the same general curvature.
Claim 16
Dependent Claim
15 words
The method of claim 1 further including scanning the sensor head along a second path.
Claim 17
Dependent Claim
16 words
The method of claim 15 wherein the second path is generally transverse to the first path.
Claim 18
Dependent Claim
16 words
The method of claim 15 wherein the second path is generally parallel to the first path.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-09 | 1993-10-09 | 1994-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-09 | 1997-10-09 | 1998-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-09 | 2001-10-09 | 2002-04-10 | $7700.00 | Window Closed / Lapsed |