Acoustic alarm device for watches
This application is a divisional of copending application Ser. No. 164,769, filed on June 30, 1980, now U.S. Pat. No. 4,351,041. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an acoustic alarm device for watches. 
     It is desirable for miniaturizing a watch to provide the acoustic alarm device in an upper portion of the watch case which is not used for the watch movement or module, such as a band connecting portion of the watch case. However, the thickness of the alarm device must be decreased so as to be mounted in a thin portion of the watch case and moreover watertight means must be provided. Further, the alarm device must be constructed to be inserted into the watch case from the upper side thereof. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a compact alarm device having perfect watertightness. Another object of the present invention is to provide an alarm device which may be mounted on a watch case. 
    
    
     Other objects will become more apparent from the following description with reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of an acoustic alarm device of the present invention; 
     FIG. 2 is a sectional view taken along the line 2--2 of FIG. 1; 
     FIG. 2 is a sectional view taken along the line 3--3 of FIG. 1; 
     FIG. 4 is a sectional view of a packing; 
     FIG. 5 is a sectional view showing a principal part of a second embodiment of the present invention and; 
     FIG. 6 is a sectional view showing a principal part of a third embodiment of the present invention; 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 to 4, numeral 10 designates a watch case having a module (not shown) therein and a display portion 10a on an upper portion thereof. In an upper portion of a band-connecting portion of the watch case, an oblong recess 10b is provided for mounting an alarm device. A communication hole 10c is provided in the bottom of the recess 10b for electrical connection between the module in the watch case 10 and the alarm device in the recess. 
     A vibration plate 41 has a piezoelectric element 42 securely fixed to the underside thereof. Numeral 43 designates, a cover 43, and 44 is an ornament plate. The vibration plate 41 has a peripheral upright portion 41a and a downwardly projected portion 41b adjacent the inside of the upright porton 41a. The cover 43 has a peripheral leg portion 43a engageable with the inside of the projected portion 41b of the vibration plate 41 and has a plurality of sound emanating holes 43b. The ornament plate 44 also has a plurality of sound emanating holes 44a communicating with the holes 43b of the cover 43. An annular packing 45 is disposed between the inner side wall of the recess 10b and the upright portion 41a of the vibration plate 41. The packing 45 has an inner diameter slighly smaller than the upright portion 41a and has an upper inside beveled portion 45a and lower escape portion 45b. An electric conduction ball member 46 made of elastic material such as rubber is disposed between the vibration plate 41 and the bottom of the recess 10b for grounding the vibration plate. 
     When the device is assembled, the vibration plate 41 and the cover 43 are integrated with each other by the engagement between the projected portion 41b and the leg portion 43a. The packing 45 is engaged with the recess 10b of the watch case 10 and the electric conduction ball member 46 is disposed on a suitable position of the bottom of the recess 10b. Then, the assembled vibration plate is engaged with the recess 10b with pressing against the packing 45. Thus, the vibration plate 41 is secured to the watch case 10 with a watertight sealing. The packing 45 having the escape portion 45b acts to urge the vibration plate 41 and cover 43 toward the bottom of the recess. Thus, the vibration plate and cover may be securely held in the recess without rising. 
     In the second embodiment shown in FIG. 5, the cover 43 is made of plastics. The leg portion 43a of plastics is liable to be bent inwardly by the restitution force of the packing 45 to thereby decrease watertight effect. In order to prevent the bending of the leg portion 43a and to ensure the watertight, a reinforcement member 47 is engaged with the inside of the leg portion. 
     The third embodiment of the present invention shown in FIG. 6 is similar to the second embodiment in construction having a reinforcement member 48. However, the vibration plate 41a is a flat plate and secured to the underside of the cover 43 with adhesives. The reinforcement member 48 is engaged with the vibration plate 41a and the inside of the leg portion 43a to maintain the vibration plate. The cover 43 engages directly with the packing 45 to be held in the recess 10b of the watch case. 
     From the foregoing it will be understood that the present invention provides an acoustic alarm device which may be made into a small size with a watertight sealing and mounted on the upper portion of the watch case such as a band connecting portion. Thus, the space in the watch case may be effectively used so as to reduce the size of the watch.