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: 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.