US5147523A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thin film gas sensor
Assignee: Ricoh Co Ltd
•
Filing: 1991-06-10
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Granted: 1992-09-15
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Expires: 2011-06-10
Abstract
Abstract A gas sensor senses gas using a metal oxide semiconductor whose resistance changes depending on gas adhesion on a surface of the metal oxide semiconductor. The gas sensor includes a base structure, and a gas sensitive layer formed on the base structure and made of a metal oxide semiconductor. The gas sensitive layer has a multi-layer structure which includes at least two layer portions having mutually different grain structures.
Inventors
- 👤 Shinji Yagawara
- 👤 Wasaburo Ohta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:10
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
70 words
A gas sensor which senses gas using a metal oxide semiconductor whose resistance changes depending on gas adhesion on a surface of the metal oxide semiconductor, said gas sensor comprising: a base structure; and a gas sensitive layer formed on said base structure and made of a metal oxide semiconductor, said gas sensitive layer having a multi-layer structure which includes at least two layer portions having mutually different grain structures.
Claim 2
Dependent Claim
70 words
A gas sensor which senses gas using a metal oxide semiconductor whose resistance changes depending on gas adhesion on a surface of the metal oxide semiconductor, said gas sensor comprising: a base structure; and a gas sensitive layer formed on said base structure and made of a metal oxide semiconductor, said gas sensitive layer having a multi-layer structure which includes at least two layer portions having mutually different grain structures.
Claim 3
Dependent Claim
49 words
The gas sensor as claimed in claim 1, wherein said gas sensitive layer includes a lower layer portion which has a fine-grain structure and is formed on said base structure, and an upper layer portion which has a continuous layer structure and is formed on the lower layer portion.
Claim 4
Dependent Claim
27 words
The gas sensor as claimed in claim 2, wherein said lower layer portion is made up of grains having an average diameter of 0.005 to 5 μm.
Claim 5
Dependent Claim
30 words
The gas sensor as claimed in claim 2, wherein said lower layer portion has a thickness which is at least 1/10 of a total thickness of said gas sensitive layer.
Claim 6
Dependent Claim
37 words
The gas sensor as claimed in claim 2, wherein said gas sensitive layer is made of a metal oxide material selected from a group consisting of oxides of tin, titanium, indium, nickel, tungsten, cadmium, iron and zinc.
Claim 7
Dependent Claim
37 words
The gas sensor as claimed in claim 2, wherein said base structure includes a heater layer and an insulator layer which is formed on the heater layer, said gas sensitive layer being formed on the insulator layer.
Claim 8
Dependent Claim
45 words
The gas sensor as claimed in claim 2, wherein said base structure includes a substrate having first and second surfaces and a heater layer formed on the first surface of the substrate, said gas sensitive layer being formed on the second surface of the substrate.
Claim 9
Dependent Claim
87 words
The gas sensor as claimed in claim 1, wherein said gas sensitive layer includes a lower layer portion which has a columnar grain structure and is formed on said base structure, an intermediate layer portion which has a fine-grain structure and is formed on the lower layer portion, and an upper layer portion which has a continuous layer structure and is formed on the intermediate layer portion, said columnar grain structure including grains which are arranged approximately perpendicularly to said base structure in the form of columns.
Claim 10
Dependent Claim
30 words
The gas sensor as claimed in claim 8, wherein said lower and intermediate layer portions are respectively made up of grains having an average diameter of 0.005 to 5 μm.
Claim 11
Dependent Claim
30 words
The gas sensor as claimed in claim 8, wherein said lower layer portion has a thickness which is at least 1/10 of a total thickness of said gas sensitive layer.
Claim 12
Dependent Claim
37 words
The gas sensor as claimed in claim 8, wherein said gas sensitive layer is made of a metal oxide material selected from a group consisting of oxides of tin, titanium, indium, nickel, tungsten, cadmium, iron and zinc.
Claim 13
Dependent Claim
37 words
The gas sensor as claimed in claim 8, wherein said base structure includes a heater layer and an insulator layer which is formed on the heater layer, said gas sensitive layer being formed on the insulator layer.
Claim 14
Dependent Claim
45 words
The gas sensor as claimed in claim 8, wherein said base structure includes a substrate having first and second surfaces and a heater layer formed on the first surface of the substrate, said gas sensitive layer being formed on the second surface of the substrate.
Claim 15
Dependent Claim
69 words
The gas sensor as claimed in claim 1, wherein said gas sensitive layer includes a lower layer portion which has a columnar grain structure and is formed on said base structure, and an upper layer portion which has a fine-grain structure and is formed on the lower layer portion, said columnar grain structure including grains which are arranged approximately perpendicularly to said base structure in the form of columns.
Claim 16
Dependent Claim
30 words
The gas sensor as claimed in claim 14, wherein said lower and upper layer portions are respectively made up of grains having an average diameter of 0.005 to 5 μm.
Claim 17
Dependent Claim
30 words
The gas sensor as claimed in claim 14, wherein said lower layer portion has a thickness which is at least 1/10 of a total thickness of said gas sensitive layer.
Claim 18
Dependent Claim
37 words
The gas sensor as claimed in claim 14, wherein said gas sensitive layer is made of a metal oxide material selected from a group consisting of oxides of tin, titanium, indium, nickel, tungsten, cadmium, iron and zinc.
Claim 19
Dependent Claim
37 words
The gas sensor as claimed in claim 14, wherein said base structure includes a heater layer and an insulator layer which is formed on the heater layer, said gas sensitive layer being formed on the insulator layer.
Claim 20
Dependent Claim
45 words
The gas sensor as claimed in claim 14, wherein said base structure includes a substrate having first and second surfaces and a heater layer formed on the first surface of the substrate, said gas sensitive layer being formed on the second surface of the substrate.
Claim 21
Dependent Claim
70 words
The gas sensor as claimed in claim 1, wherein said gas sensitive layer includes a lower layer portion which has a columnar grain structure and is formed on said base structure, and an upper layer portion which has a continuous layer structure and is formed on the lower layer portion, said columnar grain structure including grains which are arranged approximately perpendicularly to said base structure in the form of columns.
Claim 22
Dependent Claim
27 words
The gas sensor as claimed in claim 20, wherein said lower layer portion is made up of grains having an average diameter of 0.005 to 5 μm.
Claim 23
Dependent Claim
30 words
The gas sensor as claimed in claim 20, wherein said lower layer portion has a thickness which is at least 1/10 of a total thickness of said gas sensitive layer.
Claim 24
Dependent Claim
37 words
The gas sensor as claimed in claim 20, wherein said gas sensitive layer is made of a metal oxide material selected from a group consisting of oxides of tin, titanium, indium, nickel, tungsten, cadmium, iron and zinc.
Claim 25
Dependent Claim
37 words
The gas sensor as claimed in claim 20, wherein said base structure includes a heater layer and an insulator layer which is formed on the heater layer, said gas sensitive layer being formed on the insulator layer.
Claim 26
Dependent Claim
45 words
The gas sensor as claimed in claim 20, wherein said base structure includes a substrate having first and second surfaces and a heater layer formed on the first surface of the substrate, said gas sensitive layer being formed on the second surface of the substrate.
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) | 1995-09-15 | 1996-03-16 | 1996-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-15 | 2000-03-16 | 2000-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-15 | 2004-03-16 | 2004-09-15 | $7700.00 | Window Closed / Lapsed |