Abstract: An alarm buzzer includes a bobbin mounted within a housing and having a base portion and a hollow cylindrical portion. The mounting plate is interposed between the bottom wall and the base portion. A coil is wound around the cylindrical portion, and opposite ends of the coil are connected respectively to a pair of terminals mounted on the base portion. An iron core extends through the cylindrical portion of the bobbin and is held in engagement with the bobbin and the bottom wall, thereby holding the bobbin and the mounting plate against movement with respect to the housing. An armature is resiliently supported on the mounting plate for being attracted into the core upon energization of the electromagnet. Upon de-energization of the electromagnet, the armature is returned into striking contact with a vibratory plate to produce a sound under the restoring force of the resilient means.

Abstract: A motor actuated buzzer includes a motor mounted on a body, at least one cam member fixedly mounted on an output shaft of the motor, a sound generating plate mounted on the body, and a hammer for striking the sound generating plate, the cam having a plurality of radial protrusions. At least one leaf spring is fixed to the body at one end thereof and urged toward the cam member. The leaf spring carries the hammer intermediate opposite ends thereof and having at a free end thereof a projection. The radial protrusions are engageable with the projection upon rotation of the cam member to oscillate the leaf spring to intermittently bring the hammer into striking contact with the sound generating plate to produce a buzzing sound.

Abstract: A tamper switch includes an elongated tamper element mounted on a casing for movement along an axis thereof between an inoperative and an operative position. An urging device normally urges the tamper element into one of the operative and inoperative positions. A pair of elongated resilient contact plates are mounted within and fixedly secured to the casing at their one ends, the pair of contact plates being disposed in generally parallel opposed relation to each other. Each of the contact plates has a slit extending along a length thereof and opening to the other end thereof. A contact element is secured to the tamper element. The contact element is urged in between the pair of contact plates to make electrical contact therewith when the tamper element is brought into the operative position. By virtue of the provision of the slit in each contact plate, the contact plate is held in contact with the contact element throughout substantially the entire width thereof.

Abstract: An improved magnetic proximity switch which comprises an auxiliary permanent magnet for retaining normal closing and a yoke arranged so that the magnetic path of said auxiliary permanent magnet and the magnetic path formed by the magnetic flux from outside are added each other. Thus, the switch has such merits that the contact pressure at the time of normal closing is raised, the working sensitivity is enhanced, with a small external magnet, without mis-working due to shock or vibration from outside and the like.

Abstract: A motor driven bell sound generation system is constructed such that rotational movement of a motor is converted into reciprocative hammering operation or single directional striking operation of hammer means via a crank means, driving means with radial protrusions on the outer periphery thereof or lever mechanism, whereby the required quality and volume of bell sounding is produced. A resilient means comprising a coil spring-leaf spring combination or single coil spring may be arranged for conversion of the rotational movement of the motor into the hammering or striking operation of the hammer means between the motor and the hammer means. Rotational movement of the motor may be converted into a reciprocative striking operation of the hammer means via a combination of driving member having ratchet on the outer periphery and a leaf spring.

Abstract: An alarm buzzer comprising an electromagnet, a yoke on which said electromagnet is mounted while maintaining insulation from the housing, an armature which is held with a plate spring on said yoke and is attracted by said electromagnet, a vibratory plate which contacts said armature, and a housing which incorporates the above components, wherein the bobbin of said electromagnet is made of an insulating material and consists of a hollow cylinder which receives an iron core in it and is wrapped with coil on its outer periphery, first flange provided on one end of said hollow cylinder, second flange provided on the other end of the hollow cylinder and at least one hollow projection provided on said second flange in the direction parting from said first flange, said yoke is provided with at least one hole into which said hollow projection of the bobbin is inserted, and the bobbin and the yoke are fixed to the housing of the alarm buzzer by a fixture which is inserted into the hollow projection of the bobbin inser

Abstract: An alarm buzzer comprising an electromagnet, a yoke on which said electromagnet is mounted while maintaining insulation from the housing, an armature which is held with a plate spring on said yoke and is attracted by said electromagnet, a vibratory plate which contacts said armature, and a housing which incorporates the above components, wherein the bobbin of said electromagnet is made of an insulating material and consists of a hollow cylinder which receives an iron core in it and is wrapped with coil on its outer periphery, first flange provided on one end of said hollow cylinder, second flange provided on the other end of the hollow cylinder and at least one hollow projection provided on said second flange in the direction parting from said first flange, said yoke is provided with at least one hole into which said hollow projection of the bobbin is inserted, and the bobbin and the yoke are fixed to the housing of the alarm buzzer by a fixture which is inserted into the hollow projection of the bobbin inser