Rotary electric shaver

1. A rotary electric shaver comprising:

a shaver main body;

a plurality of cutter units, each including a substantially disk-shaped outer cutter and an inner cutter rotating in resilient contact with the inner surface of the outer cutter;

a shaver head pivotably provided on the shaver main body;

an outer cutter frame included in said shaver head and supporting the outer cutters in a vertically movable fashion;

a main drive shaft for transmitting, via a first universal joint, a rotational output of a motor provided inside the shaver main body to a driving mechanism provided inside the shaver head;

a plurality of inner cutter drive shafts provided in the shaver head and rotationally driven by the driving mechanism; and

a plurality of second universal joints for transmitting a rotation of the inner cutter drive shafts to the inner cutters of corresponding cutter units; wherein

the first universal joint is provided in a vicinity of a pivotal center of the shaver head,

said first universal joint comprises a coupling-element, which is securely attached to said main drive shaft that is provided on a shaver main body side, and a coupled-element, which is securely attached to a driven shaft that is provided on a driving mechanism side, and

radial pawls, provided in one of the coupling-element and the coupled-element, and axial elongated grooves, provided in the other one of the coupling-element and the coupled-element, are brought into mutual engagement.

2. The rotary electric shaver according to claim 1 , wherein

a junction between the shaver head and the shaver main body is formed with a downwardly convex hemispherical sliding surface and a sliding surface support portion, one of said sliding surface and said support portion being provided on one of said shaver head and said shaver main body, and the other one of said sliding surface and said support portion being provided on the other one of said shaver head and said shaver main body; and

said first universal joint is disposed near a center of curvature of said hemispherical sliding surface.

3. The rotary electric shaver according to claim 1 , wherein a junction between the shaver head and the shaver main body is surrounded by a bellows-like boot, and said bellows-like boot resiliently pulls said shaver head and said shaver main body together toward each other.

4. A rotary electric shaver comprising:

a shaver main body;

a plurality of cutter units, each including a substantially disk-shaped outer cutter and an inner cutter rotating in resilient contact with the inner surface of the outer cutter;

a shaver head pivotably provided on the shaver main body;

an outer cutter frame included in said shaver head and supporting the outer cutters in a vertically movable fashion;

a main drive shaft for transmitting, via a first universal joint, a rotational output of a motor provided inside the shaver main body to a driving mechanism provided inside the shaver head;

a plurality of inner cutter drive shafts provided in the shaver head and rotationally driven by the driving mechanism; and

a plurality of second universal joints for transmitting a rotation of the inner cutter drive shafts to the inner cutters of corresponding cutter units, wherein

the first universal joint is provided in a vicinity of a pivotal center of the shaver head, and

said driving mechanism housed in said shaver head comprises:

a driving spur gear which is integral with a coupled-element of said first universal joint, and

a plurality of driven spur gears each securely attached to said inner cutter drive shaft of each one of said cutter units and meshed with said driving spur gear.

5. The rotary electric shaver according to claim 4 , wherein

a driven shaft of said first universal joint is integral with said driving spur gear, and

a center of a lower face of said driving spur gear is recessed, and the pivotal center of said shaver head is disposed within said recess.