EP0493815A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Apparatus for detecting extraneous substance on glass plate
Assignee: Hitachi High-Tech Corp
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Filing: 1991-12-27
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Granted: —
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Expires: 2011-12-27
Abstract
Abstract An apparatus for detecting extraneous substances on a glass plate (1) comprises a first light projecting system (41) arranged above the glass plate surface under examination for irradiating the surface with an S-polarized laser beam at a first elevation angle, a second light projecting system (42) arranged above the surface for irradiating it with a P-polarized laser beam at a second elevation angle greater than the first elevation angle, and a light receiving system (5) for receiving light scattered from the surface at an elevation angle smaller than the first elevation angle. The light receiving system (5) is arranged on a side opposite to the direction of irradiation with a normal line set up at the beam irradiation point therebetween. The output level of the P-polarized beam is set in specific relation to the S-polarized beam.
Inventors
- 👤 Noboru Kato
- 👤 Izuo Horai
- 👤 Toshihiro Kimura
- 👤 Mitsuyoshi Koizumi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 20:00
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/84; G01N21/88; G01N21/94; G01N2021/4792; G01N21/8851; G01N2021/8854; G01N2021/8867; G01N2021/887; G01N21/95; G01N2021/9513; G01N21/9501
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
246 words
An apparatus for detecting extraneous substance on a glass plate, comprising a first light projecting system (41, 461, 462) for irradiating the surface of the glass plate (1) with an S-polarized laser beam at a first elevation angle, as viewed from the surface, a second light projecting system (42, 47) for irradiating the surface under examination with a P-polarized laser beam at a second elevation angle greater than the first elevation angle, and a light receiving system (5) for receiving light scattered from the surface under examination at a third elevation angle smaller than the first elevation angle, the light receiving system being arranged in a direction opposite to the direction of irradiation with a normal line set up at the beam irradiation point therebetween, wherein a first detection level is used when an extraneous substance on the surface under examination is irradiated with an S-polarized beam, a second detection level is used when the extraneous substance is irradiated with the S-polarized beam through the glass substrate, with the glass plate being turned upside down, a third detection level is used when the extraneous substance is irradiated with the P-polarized beam, and a fourth detection level is used when the extraneous substance is irradiated with the P-polarized beam through the glass plate, with the glass plate turned upside down, and wherein the output level of the P-polarized beam is set so that the third and fourth detection levels are between the first and second detection levels.
Claim 2
Dependent Claim
45 words
The apparatus of claim 1, wherein when the signal level obtainable by the light receiving system corresponding to the irradiation with the S-polarized beam is greater than that corresponding to the P-polarized beam, the extraneous substance is judged as existing on the surface under examination.
Claim 3
Dependent Claim
48 words
The apparatus of claim 1 or 2, wherein when the signal level obtainable by the light receiving system corresponding to the irradiation with the P-polarized beam is greater than that corresponding to the S-polarized beam, the extraneous substance is judged as existing on the back surface under examination.
Claim 4
Independent Claim
41 words
The apparatus of any of claims 1 to 3, wherein the output of the beam from the second light projecting system (42, 47) is from two to four times greater than that from the first light projecting system (41, 461, 42).
Claim 5
Independent Claim
53 words
The apparatus of any of claims 1 to 4, wherein the glass plate (1) is a glass substrate for use in a liquid crystal panel, and wherein the first elevation angle ranges from 7° to 25°, the second elevation angle from 57° to 75°, and the third elevation angle from 5° to 15°.
Claim 6
Dependent Claim
22 words
The apparatus of claim 4, wherein the difference between the first and second elevation angles is equal to or greater than 50°.
Claim 7
Dependent Claim
41 words
The apparatus of claim 6, wherein the first elevation angle is from 17° to 23°, preferably about 18°, the second elevation angle is 67° to 73°, preferably about 70°, and the third elevation angle is 7° to 13°, preferably about 8°.
Claim 8
Dependent Claim
29 words
The apparatus of claim 7, wherein said glass substrate (1) is about 1 mm thick and an electrode for liquid crystal display is formed on the surface under examination.
Claim 9
Independent Claim
21 words
The apparatus of any of claims 1 to 8, wherein the extraneous substance is a flaw in the glass plate (1).
References Cited (Backward Citations)
No citation records indexed.
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