Patent ID: 7904227

Claim:
An electric parking brake system, comprising: a brake that is fitted to a wheel and that includes a rotating body which has a friction face and which rotates together with the wheel, a friction member which is fitted to a non-rotating body so as to be movable relative to the non-rotating body, and a pushing mechanism that pushes the friction member against the friction face of the rotating body; an electric motor; a motion conversion mechanism that converts a rotation of a rotating shaft of the electric motor into a linear motion of an output member of the motion conversion mechanism; a connection unit that is connected at one end to the output member of the motion conversion mechanism, and that is connected at an other end to the pushing mechanism; a clutch that maintains a force with which the friction member is pushed against the friction face in the brake, when electric current is not supplied to the electric motor; a shifting operation member that is moved in response to an operation performed by a driver, and that is held at a position to which the shifting operation member has been moved; a shift position sensor that detects a shift position which is the position of the shifting operation member; and a brake release unit that releases the brake by operating the electric motor based on a change in a position of the shifting operation member, wherein an operation of the electric motor is prohibited for at least a period from when an ignition switch of a vehicle is turned on until when an initial check is completed, and wherein the brake release unit includes a lag position determination unit, such that while the operation of the of the electric motor is prohibited, when the shift position detected by the shift position sensor is continuously the same for a predetermined time or longer, the lag position determination unit determines that the shift position detected by the shift position sensor is a first shift position and stores the shift position as the first shift position, and when the shift position detected by the shift position sensor is continuously the same for the predetermined time or longer and different from the first shift position, the lag position determination unit determines, at the same time that the operation of the electric motor is permitted or after the operation of the electric motor is permitted, that the shift position is a second shift position, stores the shift position as a second shift position, and makes a determination that the shift position has been changed, and an after-permission brake release unit that releases the brake when the lag position determination unit determines that the shift position has been changed, that the first position is a shift position at which the vehicle is at a standstill, and that the second shift position is a shift position at which the vehicle moves.