Patent ID: 8136376

Claim:
An electric lock device comprising: a movable member; a cam member rotated in an unlocking direction and a locking direction by driving of a drive source; and a lock member including a cam contact surface in contact with a sliding surface of the cam member, the lock member following the sliding surface to move between a locking position for inhibiting movement of the movable member and an unlocking position for allowing the movement of the movable member, wherein a cam profile of the sliding surface is set so that a rotary torque of the cam member for moving the lock member from the locking position to the unlocking position is calculated by the equation T=W·R ·(Tan α+μ)/(1−μ·Tan α), with T=the rotary torque of the cam member, R=a radial length from a rotation center of the cam member, W=a constant load on the cam member, α=an angle of inclination between load W and the cam, and μ=a constant coefficient of kinetic friction; the rotary torque of the cam member is maintained at a constant value over a certain range of rotation angles of the cam member, and the lock member is moved in the certain range of rotation angles, wherein the cam profile comprises a high-load region and a low-load region within a range of movement of the lock member from the locking position to the unlocking position, a load on the drive source in the low-load region being lower than a load on the drive source in the high-load region, the high-load region corresponds to the certain range of rotation angles, and in the low-load region, the cam profile is set so that a shift stroke amount of the lock member per rotation angle of the cam member is larger than that in the high-load region.