Patent ID: 6925684

Claim:
A hinge device having a driving motor and a reduction module for reducing revolutions per minute of the driving motor, comprising: a driving shaft for receiving a rotating force of the driving motor transmitted through the reduction module, the driving shaft having a flat section with a “D”-shaped cross section over a certain length; a driving cam capable of linearly reciprocating on a part of the driving shaft in a longitudinal direction within a range of the flat section having the “D”-shaped cross section, the driving cam being coupled to the driving shaft to rotate according to rotation of the driving shaft, the driving cam being formed at one end thereof with a plurality of longitudinally extending teeth spaced apart from each other at equal angles; and a driven cam installed to receive elastic force so as to tightly engage with the driving cam in a state in which it faces the driving cam, the driven cam being formed at one end thereof with a plurality of teeth spaced apart from each other at equal angles to be engaged with the teeth of the driving cam, thereby simultaneously rotating according to rotation of the driving cam, wherein, if the driven cam rotates by external force, the teeth of the driving cam are disengaged from the teeth of the driven cam, thereby preventing a driving force of the driven cam from being transmitted to the driving cam.