Patent US4580439A successfully refreshed from Google Patents.
US4580439A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low power gas detector
Assignee: Ricoh Seiki Co Ltd
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Filing: 1984-02-07
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Granted: 1986-04-08
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Expires: 2004-02-07
Abstract
Abstract A gas detector includes a gas detecting element comprised of a metal oxide semiconductor material which changes its value of electrical resistance at an elevated temperature when it absorbs a gas. In one form, the gas detecting element is supported in the form of a bridge so as to increase its response speed by making thermal capacity as small as possible. In another form, the gas detecting element is supported in the form of a cantilever, more preferably in the form of a ring as formed along the periphery of a overhang portion of a disc-shaped layer of electrically insulating material. Also provided is a process for manufacturing a thin film of metal oxide, which may be advantageously used as a gas detecting element of a gas detector or a transparent electrode, for example, in a liquid crystal panel.
Inventors
- 👤 Junji Manaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:29
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; H; H01; H01J; H01J2217/00; H01J2217/38; H01J2217/49; H01J2217/492; H01J2217/49207
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
87 words
A gas detector comprising: a substrate; an insulating layer formed on said substrate and having a projection which extends into the air; at least two electrically conductive heater strips formed on said projection as spaced apart from each other; means for applying a driving signal to said heater strips; a gas detecting layer formed as extending between said heater strips, said gas detecting layer changing its electrical resistance when it absorbs a gas; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 2
Dependent Claim
87 words
A gas detector comprising: a substrate; an insulating layer formed on said substrate and having a projection which extends into the air; at least two electrically conductive heater strips formed on said projection as spaced apart from each other; means for applying a driving signal to said heater strips; a gas detecting layer formed as extending between said heater strips, said gas detecting layer changing its electrical resistance when it absorbs a gas; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 3
Dependent Claim
16 words
A gas detector of claim 1 wherein said gas detecting layer comprises a metal oxide semiconductor.
Claim 4
Dependent Claim
16 words
A gas detector of claim 2 wherein said projection is in the form of a bridge.
Claim 5
Dependent Claim
16 words
A gas detector of claim 2 wherein said projection is in the form of a cantilever.
Claim 6
Dependent Claim
30 words
A gas detector of claim 3 wherein said projection is defined in an elongated manner whose longitudinal direction is in a particular relation to a crystal orientation of said substrate.
Claim 7
Dependent Claim
28 words
A gas detector of claim 5 wherein said substrate is provided with a void space in its top surface and said bridge-formed projection extends above said void space.
Claim 8
Dependent Claim
29 words
A gas detector of claim 1 wherein said means for detecting includes a detector strip of electrically conductive material formed on said projection as sandwiched between said heater strips.
Claim 9
Dependent Claim
27 words
A gas detector of claim 7 further comprising electrode pads formed on said insulating layer and each connected to one end of said heater and detector strips.
Claim 10
Dependent Claim
120 words
A gas detector comprising: a substrate having a ridge which is generally circular in cross section; an electrically insulating layer formed on said ridge having an overhang portion which is also generally circular and extending beyond the periphery of said ridge into the air over a predetermined amount; at least two strips of electrically conductive material formed on said overhang portion as spaced apart from one another; means for applying electrical current to at least one of said strips; a gas detecting layer formed in contact with at least one of said strips, said gas detecting layer changing its electrical resistance when it absorbs a gas; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 11
Dependent Claim
120 words
A gas detector comprising: a substrate having a ridge which is generally circular in cross section; an electrically insulating layer formed on said ridge having an overhang portion which is also generally circular and extending beyond the periphery of said ridge into the air over a predetermined amount; at least two strips of electrically conductive material formed on said overhang portion as spaced apart from one another; means for applying electrical current to at least one of said strips; a gas detecting layer formed in contact with at least one of said strips, said gas detecting layer changing its electrical resistance when it absorbs a gas; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 12
Dependent Claim
16 words
A gas detector of claim 9 wherein said strips are formed circularly on said overhang portion.
Claim 13
Dependent Claim
111 words
A gas detector comprising: a substrate provided with a recess circular in shape at its top surface; an electrically insulating layer formed on said top surface having an overhang portion extending into said recess over a predetermined amount; at least two ring-shaped strips of electrically conductive material formed on said overhang portion as spaced apart from one another; means for applying electrical current to at least one of said strips; a gas detecting layer formed in contact with at least one of said strips, said gas detecting layer changing its electrical resistance when it absorbs a gas; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 14
Dependent Claim
111 words
A gas detector comprising: a substrate provided with a recess circular in shape at its top surface; an electrically insulating layer formed on said top surface having an overhang portion extending into said recess over a predetermined amount; at least two ring-shaped strips of electrically conductive material formed on said overhang portion as spaced apart from one another; means for applying electrical current to at least one of said strips; a gas detecting layer formed in contact with at least one of said strips, said gas detecting layer changing its electrical resistance when it absorbs a gas; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 15
Dependent Claim
109 words
A gas detector comprising: an electrically insulating layer; at least two electrodes formed on said insulating layer as spaced apart from each other; a gas detecting layer capable of being self-heated to a predetermined temperature when current is passed therethrough formed on said insulating layer as extending between said two electrodes, said gas detecting layer changing its electrical resistance when it absorbs a gas; means for applying electrical current between said two electrodes for passing said current through said gas detecting layer thereby causing said gas detecting layer to be self-heated to a predetermined temperature; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 16
Dependent Claim
109 words
A gas detector comprising: an electrically insulating layer; at least two electrodes formed on said insulating layer as spaced apart from each other; a gas detecting layer capable of being self-heated to a predetermined temperature when current is passed therethrough formed on said insulating layer as extending between said two electrodes, said gas detecting layer changing its electrical resistance when it absorbs a gas; means for applying electrical current between said two electrodes for passing said current through said gas detecting layer thereby causing said gas detecting layer to be self-heated to a predetermined temperature; and means for detecting changes in the electrical resistance of said gas detecting layer.
Claim 17
Dependent Claim
28 words
A gas detector of claim 12 wherein said insulating layer includes a projection which extends into the air and said gas detecting layer is formed on said projection.
Claim 18
Dependent Claim
40 words
A gas detector of claim 13 wherein each of said electrodes includes a lead-out portion which extends partly along said projection whereby the connections between said gas detecting layer and each of said lead-out portions are located on said projection.
Claim 19
Dependent Claim
32 words
A gas detector of claim 13 further comprising a support having a pair of ridges and wherein said projection is supported as extending between said ridges in the form of a bridge.
Claim 20
Dependent Claim
25 words
A gas detector of claim 15 wherein said bridge-formed projection becomes wider toward its center between its base ends which are supported on said ridges.
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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) | 1989-04-07 | 1989-10-07 | 1990-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-07 | 1993-10-07 | 1994-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-07 | 1997-10-07 | 1998-04-08 | $7700.00 | Window Closed / Lapsed |