Patent ID: 7981060

Claim:
An ultrasound applying skin care device comprising: a housing provided with an applicator head which applies ultrasound to a user's skin; and a driver circuit which gives an electric pulse for actuating said applicator head to generate the ultrasound; said applicator head comprising: a vibrator element generating the ultrasound, and a horn having a mounting face and a skin opposing face which is adapted in use to come into contact with the skin, said horn carrying said vibrator on said mounting face to transmit said ultrasound to the skin through said skin opposing face, said vibrator element and said horn being integrated into a combined vibration mass which resonates with the electric pulse of a resonant frequency from said driver circuit to generate the ultrasound, said combined vibration mass giving a first electrically equivalent impedance when it is normally loaded by contact with the skin, and gives a second electrically equivalent impedance when it is unloaded, a load detecting circuit which is connected to monitor whether said combined vibration mass gives the first or second electrically equivalent impedance and provides a load detection signal only upon seeing said first electrically equivalent impedance, a control circuit which limits or stops the electric pulse when the load detection signal is not received within a predetermined time period, wherein said combined vibration mass has a structure that restrains vibrations at a center portion of said combined vibration mass to reduce a parasitic resonance, thereby differentiating said first electrically equivalent impedance from said second electrically equivalent impedance for discrimination therebetween, and wherein said vibrator element comprises a piezoelectric element in the form of a circular disc having flat upper and lower end faces, and upper and lower electrodes respectively deposited on said upper and lower end faces, said electric pulse being applied across said upper and lower electrodes, and wherein said horn has a center hole for restraining the vibrations at the center of said combined vibration mass.