Buzzer mechanism for alarm clock or the like
FIELD OF INVENTION 
     The present invention relates to a buzzer mechanism for an alarm clock or the like. 
     BACKGROUND OF THE INVENTION 
     In a conventional buzzer called the stator-buzzer type, a buzzer vibrator is fixed at one end to a stationary member and is vibrated by making use of the magnetic flex from the stator of a motor for driving the clock. In a conventional mechanism of this kind the vibrator is changed between operating state and non-operating state through an alarm switch lever linking with an unlocking mechanism. As many component parts are required, the structure becomes complex and laborious to assemble with consequent high cost of manufacture. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to eliminate the disadvantage described above. Thus an object of the present invention is to provide a buzzer mechanism which is simple in structure by dispensing with an intermediate part between the unlocking mechanism and the vibrator. Another object of the present invention is to provide a buzzer mechanism which operates steadily and produces a good buzzer sound. 
     According to a feature of the present invention, there is provided a buzzer mechanism for an alarm clock or the like comprising an unlocking mechanism including an unlocking drum and an hour wheel and a vibrator rockably supported on a base plate and provided with a projection contacting the hour wheel and with a vibration arm. The vibrator member is biased toward the hour wheel so that when the hour wheel moves axially the vibration arm is brought into the magnetic field of a buzzer yoke connected with the stator of a motor for driving the clock so as to produce a buzzer sound. A stop lever is operable manually to rock the vibrator member back to an inoperative position. The vibrator mechanism in accordance with the present invention is thus of simple construction whereby it is less expensive to manufacture and is reliable and durable in its operation. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The nature, object and advantages of the invention will be more fully understood from the following description of preferred embodiments shown by way of example in the accompanying drawings in which: 
     FIG. 1 is an elevational view partly in section of an embodiment of the present invention, 
     FIG. 2 is an enlarged section along the lines II--II in FIG. 1, 
     FIG. 3 is an enlarged section along the lines III--III in FIG. 1, and 
     FIG. 4 is an enlarged section similar to FIG. 2 but showing a modification. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, a base plate 1 is provided with a tubular projection or pipe 2. A vibrator member 3 is rockably supported about the pipe 2. The vibrator member 3 also functions as an alarm switch lever. A push plate 4 made of spring material is rotatably supported about the pipe 2. The push plate 4 is provided with three protuberances or legs 4a, 4b and 4c which engage the vibrator member 3. A coil spring 5 is provided around the pipe 2. The coil spring 5 pushes the vibrator 3 through the push plate 4 to the base plate 1. The push plate 4 is provided with a bent hook portion 4d engaged with a hole 3a provided in the vibrator member 3 so that the push plate 4 and the vibrator member 3 rock together. One end portion of the coil spring 5 is engaged with a pin 6 on the base plate 1 while the other end engages with a projection 3b on the vibrator member 3 thereby applying counterclockwise rotational force to the vibrator member. A stud 7 is secured to the pipe 2 and holds down the coil spring 5. Thus the coil spring 5 presses the vibrator member 3 against the base plate 1 and also biases the vibrator member 3 in a counterclockwise direction. 
     The vibrator member 3 is provided at its upper left end portion with a projection 3c which abuts against the right side of an hour wheel 8 by reason of the bias of the coil spring 5. The hour wheel 8 is a component part of unlocking mechanism 9. As the hour wheel 8 moves in an axial direction from the position shown, the vibrator member 3 is permitted to rock in a counterclockwise direction. The unlocking mechanism 9 is conventional. A minute shaft 10 penetrates through the center of the hour wheel 8 and an unlocking drum 11 is rotatable about the shaft 10. The unlocking drum 11 is rotatable manually to set the alarm time. The hour wheel 8 is rotated once in 24 hours by a motor 12 through reducing gear mechanism (not shown in the drawings). The hour wheel 8 is provided on its left side with a triangular projection 8a and the unlocking drum 11 is provided with a hole 11a engageable with such projection when the hour wheel has rotated to a position corresponding to the time for which the unlocking drum 11 is set. A click spring 13 is provided for preventing reverse rotation of the unlocking drum 11. 
     The vibrator member 3 is provided with a raised vibration arm 3d extending toward the right. The vibration arm 3d is so designed that it may be moved to a position opposing a buzzer yoke 14. The buzzer yoke 14 is L-shaped and is connected with the stator 15 of the motor 12. A coil 16 is wound around the buzzer yoke 14 and the stator 15 on a bobbin 17. A power source cord 18 is connected to the coil 16. 
     The base plate 1 is provided with a stopper 19 which defines the range of rocking movement of the vibrator member 3 and keeps a predetermined gap between the raised vibration arm 3d and the buzzer yoke 14. 
     An alarm stop lever 20 is slidable up and down on the base plate 1. A coil spring 21 is wound around the alarm stop lever 20 between a pushbutton 22 on the alarm stop lever and a guide member 23 projecting from the base plate 1 so as to bias the stop lever 20 upwardly. The alarm stop lever 20 is provided on its backside with a pin 24 which is engageable with an upper portion of the vibrator member 3. When the pushbutton 22 is pushed downwardly the pin 24 engages the vibrator member 3 so as to rotate it in a clockwise direction from the operative position in which the vibration arm 3d faces the buzzer yoke 14, as shown in dot-dash lines in FIG. 1, to an inoperative position, shown in solid lines in FIG. 1, in which the vibration arm 3d is apart from the buzzer yoke 14. 
     In operation an alarm time is set by turning the unlocking drum 11. At the set time the triangular projection 8a on the hour wheel 8 engages with the hole 11a in the unlocking drum 11 and the hour wheel 8 moves toward the left. This permits the vibrator member 3 to turn counterclockwise around the pipe 2 until the vibration arm 3d faces the buzzer yoke 14, as shown in dot-dash lines in FIG. 1. The magnetic flux of the buzzer yoke 14 produces vibration of the vibration arm 3d which in turn strikes the buzzer yoke to produce the buzzer sound. 
     In this type of buzzer it is essential to keep the vibration arm 3d spaced from the buzzer yoke 14 by a predetermined distance. Since the vibrator member 3 is rockably supported, it is difficult to keep the space constant. To overcome this difficulty the push plate 4 is provided for applying pressure by the coil spring 5 to the vibrator member 3 by its three legs 4a, 4b and 4c. By reason of application of pressure in this manner, the vibrator plate 3 always contacts the base plate 1 over a wide area and variation of the space between the vibration arm and the buzzer yoke 14 is minimized. In case the pressure the vibrator member 3 applies to the base plate is too weak, the above described effect decreases and in case the pressure is too strong, the rocking motion of the vibrator member 3 is hindered. The force of the coil spring 5 and the spring force of the push plate 4 are therefore suitably designed. Since the vibrator member 3 is pressed at its base portion by the push plate 4 as though it is fixed by the push plate, the vibration arm 3d performs vibratory motion similar to that of a cantilever. The vibrator accordingly produces a good buzzer sound without rattle. 
     In a modification as illustrated in FIG. 4, the coil spring 5 is eliminated and the vibrator member 53 is pushed against the base plate 51 by a spring push plate 54 which is held down by a stud 57 secured in the pipe 52 and is provided with three downwardly bent leg portions of which only two of the portions 54a and 54b are shown and with a downwardly bent hook portion 54d engaged with a hole 53a in the vibrator member 53. In this case the vibrator member 53 is forced to turn in a counterclockwise direction by a separately provided coil spring (not shown in the drawings). The embodiment of FIG. 4 is otherwise like that of FIGS. 1 to 3.