Patent ID: 7624477

Claim:
A rotation hinge, comprising: a base having a receiving space formed in a surface of said base, and a first groove and a second groove respectively horizontally arranged at said base, one end of said first and second grooves respectively leading to said receiving space, said first groove arranged higher than said second groove; a cam module received in said receiving space of said base and having an upper cam with a first designed curve surface, and a first recess and a second recess respectively arranged at said first designed curve surface and an arc-shape projection portion positioned on each section between said first and second recesses, wherein said first and second recesses respectively adjoining one said arc-shape projection portion; a lower cam connected to said upper cam having a second designed curve surface, and a third recess and a fourth recess respectively arranged at said second designed curve surface, said arc-shape projection portion positioned on each section between said third and fourth recesses, wherein said third and fourth recesses respectively adjoining one said arc-shape projection portion, and said arc-shape projection portion of said upper cam exclusively positioned to said arc-shape projection portion of said lower cam; a first elastic sliding portion received in said first groove and contacting said first recess; and a second elastic sliding portion received in said second groove and contacting said third recess, wherein while said first elastic sliding portion contacting said arc-shape projection portions of said upper cam or said second elastic sliding portion contacting said arc-shape projection portions of said lower cam, compression force stored in said first or second elastic sliding portion is maximized.