Low power gas detector
AssigneeRicoh Seiki Company, Ltd.
InventorJunji Manaka
Life of this patent
Estimating the term…
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.
Claims16
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.
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.
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.
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.
Dependencies are inferred from the claim text.