GB1444960A - Dry shavers - Google Patents

Abstract

1444960 Dry shavers GILLETTE CO 23 July 1974 [23 Aug 1973] 39962/73 Heading B4B [Also in Division H2] A dry shaver comprises a cutter head 1, 2 means 4 mounting the cutter head for rotation about the axis of a cylindrical arcuate cutting surface defined by the cutting edges of blades 1, and driving means for rotationally reciprocating the cutter head about the axis, the driving means comprising an electrodynamic motor including a permanent magnet system 6, 7 and an electric coil system 5, one of the systems being mounted on the cutter head. As shown in Fig. 1, the cutting head is connected to a frame 3 by leaf springs which define the rotational axis and urge the cutter about the axis to a normal rest position. The leaf spring may also be used to urge the cutting edges into contact with an arcuate shearing foil (not shown); alternatively, the blades may be individually spring-loaded. Electric coils 5 are secured to the cutting head and co-operate with permanent magnets 6a-6c and 7a-7c such that when an alternating current is supplied to the coils 5, the cutting head is caused to oscillate; alternatively the supply current may be derived from a battery via an electronic control circuit delivering a succession of current pulses. The pulses may be adjusted to match the resonant frequency of the cutting head assembly. In the modification shown in Fig. 3, the cutting head is rotatable on a shaft 9 and urged to a rest position by leaf springs 4a. In a further modification, the cutting head may be transversely divided into two separate heads, each with its respective coil-and-magnet assembly arranged to oscillate the two cutting heads in antiphase thereby reducing vibration; alternatively a one-part cutter may be used, the second coil being used to drive a counterweight in antiphase to the cutter. In all the embodiments the position of the coils and magnets may be reversed.