Acceleration sensor

An acceleration sensor comprising:

• a first resonator and a second resonator which resonate at independent frequencies and each of which includes a piezoelectric body and electrodes arranged on both main surfaces thereof;
• and
• a first base plate and a second base plate;
• wherein a first unimorph acceleration detection element includes said first resonator bonded to one surface of said first base plate, and a second unimorph acceleration detection element includes said second resonator bonded to one surface of said second base plate;
• wherein each of said first and second unimorph acceleration detection elements is supported at one longitudinal end thereof or at opposed longitudinal ends thereof such that said first resonator and said second resonator are substantially diametrically opposed to each other or are arranged to face each other to allow said first resonator and said second resonator to independently deflect in response to the application of acceleration;
• wherein when said two acceleration detection elements are independently deflected in response to the application of acceleration, acceleration is detected by detecting a difference between frequency changes of said first resonator and said second resonator or a difference between impedance changes of said first resonator and said second resonator;
• and
• wherein each of said first and second resonators is a vibration mode element in which energy is trapped to the longitudinal center portion thereof, and wherein gaps are respectively provided between said first base plate and said first resonator and between said second base plate and said second resonator, said gaps being larger in area than a trapped vibration region of each of said first and second resonators and smaller in area than a deflection region of each of said first and second resonators which deflects in response to acceleration.