Piezoelectric acoustic device

A piezoelectric acoustic device comprising:

• a piezoelectric vibrator including a metal vibrating plate and a piezoelectric ceramic element joined to said metal vibrating plate;
• a casing constructed so as to receive said piezoelectric vibrator therein and formed on an inner peripheral surface thereof with an inclined joint surface section of an annular shape which surrounds an outer peripheral portion of said metal vibrating plate;
• and
• a pressure-sensitive adhesive layer formed by coating a pressure-sensitive adhesive on said inclined joint surface section;
• said outer peripheral portion of said metal vibrating plate being joined through said pressure-sensitive adhesive layer to said inclined joint surface section;
• wherein said casing includes a first casing half made of an insulating resin material and including a first opposite wall arranged opposite to one surface of said piezoelectric vibrator and a first peripheral wall arranged so as to extend from an outer peripheral portion of said first opposite wall and a second casing half including a second opposite wall arranged opposite to the other surface of said piezoelectric vibrator and a second peripheral wall arranged so as to extend from an outer peripheral portion of said second opposite wall and fitted to said first peripheral wall of said first casing half;
• said first peripheral wall and second peripheral wall being formed on an inner peripheral surface thereof with a first tapered surface section and a second tapered surface section, respectively;
• said first and second tapered surface sections cooperating with each other to form an annular groove for fitting said outer peripheral portion of said metal vibrating plate therein when said first and second peripheral walls are fitted to each other;
• said first and second tapered surface sections each being inclined so as to permit said groove to enlarge toward a central portion of said casing, one of said first and second tapered surface sections acting as said inclined joint surface section.

A piezoelectric acoustic device comprising:

• a piezoelectric vibrator including a metal vibrating plate and a piezoelectric ceramic element joined to said metal vibrating plate;
• a casing constructed so as to receive said piezoelectric vibrator therein and including a first casing half including a first opposite wall arranged opposite to one surface of said piezoelectric vibrator and a first peripheral wall arranged so as to extend from an outer peripheral portion of said first opposite wall and a second casing half including a second opposite wall arranged opposite to the other surface of said piezoelectric vibrator and a second peripheral wall arranged so as to extend from an outer peripheral portion of said second opposite wall and fitted in said first peripheral wall of said first casing half;
• said first peripheral wall and second peripheral wall being formed on an inner peripheral surface thereof with a first tapered surface section and a second tapered surface section, respectively;
• said first and second tapered surface sections cooperating with each other to form an annular groove for fitting said outer peripheral portion of said metal vibrating plate therein when said first and second peripheral walls are fitted to each other;
• said first and second tapered surface sections each being inclined so as to permit said groove to enlarge toward a central portion of said casing, one of said first and second tapered surface sections acting as said inclined joint surface section;
• and
• a pressure-sensitive adhesive layer formed by coating a pressure-sensitive adhesive on said inner peripheral surface of said first peripheral wall;
• said metal vibrating plate being held at said outer peripheral portion thereof in said casing by means of a portion of said pressure-sensitive adhesive layer positioned in said groove;
• said first peripheral wall having an opposite surface constituting a part of an inner peripheral surface thereof and arranged opposite to an outer peripheral surface of said second peripheral wall;
• said opposite surface of said first peripheral wall and said outer peripheral surface of said second peripheral wall being so configured that said opposite surface is positioned outside a virtual surface defined by a locus of a distal end of said outer peripheral surface of said second peripheral wall when said first peripheral wall and second peripheral wall are fitted to each other and said pressure-sensitive adhesive layer applied to said opposite surface is prevented from being intruded into said groove.