Patent US4752447A successfully refreshed from Google Patents.
US4752447A
Expired / Lapsed
US
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Optical filter with reversible color change
Assignee: Siemens AG
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Filing: 1986-02-26
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Granted: 1988-06-21
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Expires: 2006-02-26
Abstract
Abstract The present invention is directed to an optical filter that includes a mixture of at least one basic or acid color former or dye, preferably being a triphenyl methane system and at least one complementary acid or basic compound. The mixture reversibly changes color in response to a gas or vapor. The mixture may be embedded in a matrix substance and/or may be applied to a carrier. The color change may be measured photo-electrically.
Inventors
- 👤 Heinrich Kimmel
- 👤 Bernhard Montag
- 👤 Walter Gumbrecht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:08
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22; G01N31/221; G01N21/00; G01N21/75; G01N21/77; G01N21/78; G01N21/783
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
76 words
An optical filter for the continuous measurement of the partial pressure of gases and vapors, comprising a mixture that undergoes a reversible color change or extinction modification when exposed to certain gases and is composed of at least one compound selected from the group consisting of a basic color former, and acid color former and a dye with at least one compound selected from the group consisting of a complementary acid and a complementary basic compound.
Claim 2
Dependent Claim
76 words
An optical filter for the continuous measurement of the partial pressure of gases and vapors, comprising a mixture that undergoes a reversible color change or extinction modification when exposed to certain gases and is composed of at least one compound selected from the group consisting of a basic color former, and acid color former and a dye with at least one compound selected from the group consisting of a complementary acid and a complementary basic compound.
Claim 3
Dependent Claim
13 words
The optical filter according to claim 1, wherein the dye is a triphenyl-methane.
Claim 4
Dependent Claim
14 words
The optical filter according to claim 2, wherein the dye is crystal violet lactone.
Claim 5
Dependent Claim
14 words
The optical filter according to claim 3, wherein the complementary acid compound is bisphenol-A.
Claim 6
Dependent Claim
21 words
The optical filter according to claim 2, wherein the dye is selected from the group consisting of phthaleines and sulfone phthaleines.
Claim 7
Dependent Claim
24 words
The optical filter according to claim 1, wherein the complementary acid compound is a member of the group consisting of bisphenol-A and salicylic acid.
Claim 8
Dependent Claim
16 words
The optical filter according to claim 6, wherein the mixture is embedded in a matrix substance.
Claim 9
Dependent Claim
15 words
The optical filter according to claim 6, wherein the mixture is applied to a carrier.
Claim 10
Dependent Claim
22 words
The optical filter according to claim 1, wherein the basic complementary compound is selected form the group consisting of p-toluidine or p-chloroaniline.
Claim 11
Dependent Claim
16 words
The optical filter according to claim 9, wherein the mixture is embedded in a matrix substance.
Claim 12
Dependent Claim
15 words
The optical filter according to claim 9, wherein the mixture is applied to a carrier.
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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) | 1991-06-21 | 1991-12-21 | 1992-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-21 | 1995-12-21 | 1996-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-21 | 1999-12-21 | 2000-06-21 | $7700.00 | Window Closed / Lapsed |