Abstract: A photoelectric type fire detector has: a detector body; a printed circuit board disposed on the upper side of the detector body; conductive connecting members provided on the lower side of the detector body; terminal screws for simultaneously fixing the printed circuit board and the conductive connecting members to the detector body; an optic base directly placed on the upper side of the printed circuit board and having a labyrinth formed on the upper side thereof; hooks for fixing the optic base to the upper side of the printed circuit board; a light-emitting element and a light-receiving element arranged in a pair for detecting smoke; a bug screen provided on the outer periphery of the labyrinth of the optic base; an optic base cover covering the upper side of the optic base; and a protective cover covering the printed circuit board, the optic base, the bug screen and the optic base cover.

Abstract: A fire detector includes both a detector unit and a detector base including a base block to which the detector unit is mounted. The detector unit has an outermost peripheral wall, an engaging portion located inwardly of the outermost peripheral wall, and connecting members of a bayonet coupling. The detector base includes coupling members of a bayonet coupling engaged with the coupling members of the detector unit. The bayonet coupling is locked in place by a locking spring of the base block of the detector base, which locking spring engages the engaging portion of the detector unit. A pair of spaced apart connecting terminals for connection with a power and signal line are fixed on the base block. These terminals have small holes, respectively.

Abstract: A fire detector includes both a detector unit and a detector base including a base block (1) to which the detector unit (4) is mounted. The detector unit has an outermost peripheral wall (4a), an engaging portion (5) located inwardly of the outermost peripheral wall, and connecting members (17,18,19) of a bayonet coupling. The detector base includes coupling members (7,8,9) of a bayonet coupling engaged with the coupling members of the detector unit. The bayonet coupling is locked in place by a locking spring (3) of the base block of the detector base, which locking spring engages the engaging portion (5) of the detector unit. The engaging portion of the detector unit may define a recess (5b), in which case the locking spring has a projection (6) which will snap into the recess (5b) in the detector unit during rotation of the detector unit relative to the detector base to secure the bayonet coupling.

Abstract: A light-scattering-type smoke detector is disclosed which comprises a base portion to be secured to a ceiling, a head part forming one of the parts of a detecting portion to be detachably mounted to the base portion through setscrews passed therethrough, and a dark box forming the other of the portions of the detecting part to be detachably connected to the head part by screwing the setscrews thereto, the dark box comprising a body portion and a cover portion put one upon another. The body portion has a printed circuit board integrally secured thereto on its upper surface and the dark box is surrounded by a labyrinth around its outer periphery that is internally provided with a light projection element and a light receiving element. The smoke detector allows the dismounting of the head part from the base portion, and the dark box from the head part so that maintenance and repair of the smoke detector can be carried out quite easily.