Personal alarm device with vibrating accelerometer motion detector and planar piezoelectric hi-level sound generator

A personal alert safety system having condition responsive sensor means and alarm means indicative of personal safety conditions comprising:

• a small size portable casing, said casing comprising an internal divided two part chamber, the first part being a watertight sealed cavity and the second part being a sound resonating cavity with surrounding walls including at least one sound port providing a passage from the interior to the exterior of said resonating cavity;
• a sealed flat wall means comprising a dividing wall between said two chamber parts;
• electric and electronic control and operating circuitry means disposed in said first part of said chamber including a source of electric power, two series connected, single pole, push button control switches each having "on" and "off" positions and being spring biased to the "off" position, and flip-flop electronic switching means controlled by said control switches to enable said circuitry means to be turned "on" and "off" respectively by a sequence of simultaneous operations of said two control switches;
• said sealed flat wall means comprising a thin flat sound generating piezoelectric transducer device electrically connected to said circuitry means;
• a motion detector, and means rigidly mounting said motion detector within said first part of said two part chamber, said motion detector generating a sine wave voltage output a characteristic of which changes responsive to motion of said casing;
• and said circuitry means further including a tone oscillator, a rate oscillator and an amplifier, connected between said motion detector and said piezoelectric sound generating transducer and responsive to the output of said motion detector to cause a specific high intensity sweeping alarm signal to be emitted when the circuitry means is turned on and in the event that the casing is motionless.