US 5,399,864 AGranted

Ionization type smoke detector

AssigneeNohmi Bosai Ltd.

InventorsYoshinori Igarashi, Toru Sasaki, Ichirou Kobayashi, Ikuhisa Hatakenaka, Kentaro Higashi, Nobuo Hatori, Makoto Kamihigoshi, Kazuyuki Koganemaru

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Abstract

An ionization type smoke detector includes a detector body, a printed circuit board on the upper surface of the detector body, an electrode mount on the upper surface of the printed circuit board, an inner electrode securing the electrode mount onto the printed circuit board and which has a radioactive source, an intermediate electrode screwed onto the electrode mount in such a way as to be situated above the inner electrode, and an outer electrode covering the electrode mount, the inner electrode and the intermediate electrode. The outer electrode has a plurality of smoke inlet windows, and is fixed to the upper surface of the printed circuit board by inserting engagement members at the lower end thereof into insertion holes of the printed circuit board. The electrode mount has an FET accommodating section including a first socket, whereas a second socket is formed on the printed circuit board. Electrodes of an FET are connected to the sockets, respectively. The detector also includes a wind shield ring surrounding the outer electrode and fixed to the upper surface of the printed circuit board by hooks extending into second insertion holes of the printed circuit board. Further, a bug screen is interposed between the outer electrode and the wind shield. A shield case abuts the lower surface of the printed circuit board and is fixed to the lower surface thereof and electrically connected to the outer electrode. A protective cover covers these components and has smoke inlet windows.

Claims32

Dependent claims

An ionization type smoke detector comprising:

a detector body;
a printed circuit board which is arranged on an upper surface of said detector body and which has first, second and third insertion holes;
conductive connection metal members arranged on a lower surface of said detector body;
terminal screws for simultaneously attaching said printed circuit board and said conductive connection metal members to the detector body;
an electrode mount arranged on an upper surface of said printed circuit board;
an inner electrode which secures said electrode mount onto said printed circuit board and which has a radioactive source;
an intermediate electrode which is screwed onto said electrode mount in such a way as to be situated above said inner electrode;
an outer electrode which covers said electrode mount, said inner electrode and said intermediate electrode, which has a plurality of smoke inlet windows, and which is fastened to the upper surface of said printed circuit board by inserting engagement members formed at the lower end thereof into the first insertion holes of said printed circuit board;
a wind shield ring which surrounds said outer electrode, which controls the speed at which air flows into said smoke inlet windows, and which is fastened to the upper surface of said printed circuit board by inserting hooks formed at the lower end thereof into the second insertion holes of said printed circuit board;
a bug screen placed between said outer electrode and said wind shield ring;
a shield case which abuts against a lower surface of said printed circuit board and which is fastened to the lower surface of said printed circuit board and electrically connected to said outer electrode by inserting engagement sections formed at the upper end thereof into the third insertion holes of said printed circuit board;
and
a protective cover which covers said printed circuit board, said outer electrode and said wind shield ring, which has a plurality of smoke inlet windows, and which is fastened to the upper surface of said detector body by engaging hooks formed at the lower end thereof with said detector body.

10 more elements

An ionization type smoke detector comprising:

an electrode mount which has on its upper surface an inner electrode accommodating section having an insertion hole at the center thereof, said electrode mount further having on its lower surface a plurality of protrusions for temporary fastening;
an intermediate electrode fastened to the upper section of said electrode mount and having at its center a radiation transmission hole;
a printed circuit board having a first insertion hole formed at a position corresponding to the insertion hole of said electrode mount and a plurality of second insertion holes through which the plurality of protrusions of said electrode mount are inserted., respectively;
an inner electrode having a polygonal radioactive-source installing section and a leg section joined to said radioactive-source installing section, said leg section having a threaded portion at a free end thereof, said radioactive-source installing section being accommodated in said inner electrode accommodating section of said electrode mount, the leg section passing through the insertion hole of said electrode mount and the first insertion hole of said printed circuit board;
a radioactive source disposed on an upper surface of said radioactive-source installing section;
a threaded fastener threaded to said threaded portion of the leg section of said inner electrode at the lower surface of said printed circuit board to secure said inner electrode to said printed circuit board;
and
an outer electrode which covers said electrode mount, said inner electrode, and the intermediate electrode and which is fastened to said printed circuit board.

5 more elements

An ionization type smoke detector comprising:

a printed circuit board in which a plurality of first insertion holes are formed;
an electrode mount arranged on an upper surface of said printed circuit board;
an inner electrode which is attached to said electrode mount and to which a radioactive source is fastened;
an intermediate electrode fastened to an upper section of said electrode mount;
an outer electrode which is fastened to the upper surface of said printed circuit board in such a way as to cover said electrode mount, said inner electrode and the intermediate electrode and which has a plurality of smoke inlet windows formed in a side wall thereof;
and
a wind shield ring which surrounds said outer electrode, which has a speed reduction mechanism for airflow through the smoke inlet windows of said outer electrode, and which is fastened to the upper surface of said printed circuit board by inserting hooks formed at the lower end thereof through the first insertion holes of said printed circuit board.

4 more elements

Dependencies are inferred from the claim text.