TIJERAS

PARA MEJORAR LAS PROPIEDADES CORTANTES DE TIJERAS (1), POR EJEMPLO TIJERAS PARA CORTAR EL CABELLO (11), UN VIBRADOR ACCIONADO ELECTRICAMENTE (5) HACE QUE AL MENOS UNA MITAD DE LAS TIJERAS (4) VIBRE EN DIRECCION PARALELA A LA DIRECCION LONGITUDINAL (6) DE LA HOJA (7) DE DICHA MITAD (4) DE LA TIJERA. EL VIBRADOR (5) PUEDE INCLUIR UN GENERADOR PIEZOELECTRICO DE DESPLAZAMIENTO (8), QUE FLEXIONA LA HOJA (7) A UNA FRECUENCIA ULTRASONICA. The scissors for cutting filamentary material, especially hair, include two shanks (4) pivotally connected to each other at a pivot joint (2); respective blades (7) for cutting the filamentary material extending from the shanks (4) and an electrically powered vibrator (5) for vibrating one of the shanks in a longitudinal direction at an ultrasonic frequency and with a displacement of about 100 to 200 mum. The pivot joint (2) includes a nail (14) extending from one shank, an eccentric washer (15) embedded in the other shank which engages around the nail and a miniature motor (17) for rotating the washer (15) and the shank in which it is embedded. In other embodiments the electrically powered vibrator (5) include a piezoelectric transducer (8) arranged to connect a shank to one of the blades or an exciter coil (19) wrapped around a strut region made of a magnetostrictive material in one shank.