US3708675A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Smoke detector in which air entrance and egress are located in oppositely disposed surfaces which are shaped to cause an air velocity differential
Assignee: Furukawa Electric Co Ltd
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Filing: 1970-09-15
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Granted: 1973-01-02
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Expires: 1990-09-15
Abstract
Abstract In the smoke detector which comprises a casing having a smoke introducing inlet, and provided with a light source member and a light receiving member wherein the beam of light from the light source member is projected against smoke within the casing and the scattered light generated thereby is caught by the light receiving member, said detector is afforded the improvements (1) that the casing is provided with an inlet and an outlet for smoke flow and two air flow passages so arranged as to cause the air to flow at different velocities, when under the influence of smoke flow, such difference in velocity creating a difference in static pressure that helps introduce smoke into the casing; (2) that a light sheltering plate surrounding the light receiving member is provided within the casing said plate having apertures through which a desired portion of said scattered light is led into the light receiving member; and (3) that a reflector having a desired number of surfaces is provided, on which light beams from the light source member make multiple reflections and pass concentrically through the determined space of the smoke passages.
Inventors
- 👤 K Tashiro
- 👤 K Ikawa
- 👤 Y Okano
- 👤 Y Furuto
- 👤 T Shigihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:32
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G08; G08B; G08B17/00; G08B17/10; G08B17/103; G08B17/107; G08B17/11; G08B17/113
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
179 words
Smoke detector comprising a casing arranged to admit air containing smoke to the interior of said casing, a light source member positioned within said casing, a light receiving member positioned within said casing and arranged to receive light beams from said light source when the light beams are projected against smoke within said casing with the smoke scattering the light beams so that they impinge on said light receiving member, wherein the improvement comprises means within the interior of said casing spaced between said light source member and said light receiving member and forming a predetermined space for admitting scattered light beams to said light receiving member, and a reflector positioned within the interior of said casing between said light source member and said means having a cylindrical mirror surface for affording multiple reflection of the light beams so that the reflected light beams pass through the predetermined space provided by said means when the light beams are scattered by the smoke in the air containing smoke whereby the scattered reflected light is directed onto said light receiving member.
Claim 2
Dependent Claim
179 words
Smoke detector comprising a casing arranged to admit air containing smoke to the interior of said casing, a light source member positioned within said casing, a light receiving member positioned within said casing and arranged to receive light beams from said light source when the light beams are projected against smoke within said casing with the smoke scattering the light beams so that they impinge on said light receiving member, wherein the improvement comprises means within the interior of said casing spaced between said light source member and said light receiving member and forming a predetermined space for admitting scattered light beams to said light receiving member, and a reflector positioned within the interior of said casing between said light source member and said means having a cylindrical mirror surface for affording multiple reflection of the light beams so that the reflected light beams pass through the predetermined space provided by said means when the light beams are scattered by the smoke in the air containing smoke whereby the scattered reflected light is directed onto said light receiving member.
Claim 3
Dependent Claim
249 words
Smoke detector comprising a casing arranged to admit air containing smoke to the interior of said casing, a light source member positioned within said casing, a light receiving member positioned within said casing and arranged to receive light beams from said light source member when the light beams are projected against smoke within said casing with the smoke scattering the light beams so that they impinge on said light receiving member, wherein the improvement comprises that said Casing has a first surface and an oppositely disposed second surface with the interior of the casing arranged to receive the air containing smoke located between said first and second surfaces, a first opening in said first surface communicating with the interior of said casing, a second opening in said second surface communicating with the interior of said casing, said second surface having a shaped configuration relative to said first surface so that the length of travel of the air containing smoke over the outer surface of said casing from a common point thereon at the junction of said first and second surfaces is greater from the common point to said second opening than from the common point to said first opening thereby causing a difference in the velocity of the two flows of air containing smoke and affording a difference in the static pressures at said first and second openings so that the air containing smoke flows through the interior of said casing from said first opening to said second opening.
Claim 4
Dependent Claim
249 words
Smoke detector comprising a casing arranged to admit air containing smoke to the interior of said casing, a light source member positioned within said casing, a light receiving member positioned within said casing and arranged to receive light beams from said light source member when the light beams are projected against smoke within said casing with the smoke scattering the light beams so that they impinge on said light receiving member, wherein the improvement comprises that said Casing has a first surface and an oppositely disposed second surface with the interior of the casing arranged to receive the air containing smoke located between said first and second surfaces, a first opening in said first surface communicating with the interior of said casing, a second opening in said second surface communicating with the interior of said casing, said second surface having a shaped configuration relative to said first surface so that the length of travel of the air containing smoke over the outer surface of said casing from a common point thereon at the junction of said first and second surfaces is greater from the common point to said second opening than from the common point to said first opening thereby causing a difference in the velocity of the two flows of air containing smoke and affording a difference in the static pressures at said first and second openings so that the air containing smoke flows through the interior of said casing from said first opening to said second opening.
Claim 5
Dependent Claim
87 words
Smoke detector, as set forth in claim 2, wherein a light shielding member positioned within the interior of said casing and enclosing said light receiving member so that it blocks said light receiving member from said light source, said light shielding member having an aperture therethrough for admitting the incidence of light being scattered by smoke in the air containing smoke onto said light receiving member, and said aperture in said light shielding member being offset from the normal path of light beams from said light source.
Claim 6
Dependent Claim
101 words
Smoke detector, as set forth in claim 2, wherein a reflector is positioned within the interior of said casing between said light source member and said light receiving member and said reflector having a surface for the multiple reflection of the light beam from said light source member, means within the interior of said casing disposed between said deflector and said light receiving member and forming a predetermined space for admitting scattered light beams to said light receiving member so that the multiply reflected light beams scattered by smoke in the air containing smoke are directed onto said light receiving member.
Claim 7
Dependent Claim
153 words
Smoke detector, as set forth in claim 2, wherein said light receiving member is offset laterally from the normal path of light beams of said light source and is arranged to receive light beams from said light source when the light beams are projected against smoke within the casing with the smoke scattering the light beams from their normal path so that they impinge upon said light receiving member, the axis of said light receiving source and the normal path of the light beams from said light source are disposed at an angle of less than 90*, a light shielding member positioned within the interior of said casing and enclosing said light receiving member for blocking said light receiving member from said light source, and said light shielding member having an aperture therethrough for admitting the incidence of light scattered by the smoke in the air containing smoke into said light receiving source.
Claim 8
Dependent Claim
54 words
Smoke detector, as set forth in claim 2, wherein means for directing onto said light receiving member only the scattered light produced by the smoke in the air containing smoke passing through the casing, said means are disposed within the interior of said casing between said light source member and said light receiving member.
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) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |