Seatbelt retractor

1. A seat belt retractor comprising:

a seat belt winding device for winding up a seat belt by actuation of a motor; and

a control unit that under a predetermined condition repeats a process of stopping the actuation of the motor when an overload of the motor is detected and restarting the actuation of the motor after a lapse of a predetermined time period, the control unit comprises:

a detection module for detecting an action of an occupant entering or exiting a vehicle; and

a determination module that, using criteria, determines whether or not actuation of the motor, when stopped by detection of an overload, is to be restarted;

wherein the criteria when the occupant enters the vehicle is different from the criteria when the occupant exits the vehicle;

wherein the criteria are provided so that the determination module is more likely to determine that the actuation of the motor is not to be restarted when the occupant enters the vehicle as compared to when the occupant exits the vehicle,

wherein the retractor is configured so that when the occupant exits the vehicle, the determination module determines that the actuation of the motor is not to be restarted when a number of times of starting the actuation of the motor reaches a first number of times, and

when the occupant enters the vehicle, the determination module determines that the actuation of the motor is not to be restarted when a number of times of starting the actuation of the motor reaches a second number of times that is lower than the first number of times.

2. A seat belt retractor as claimed in any claim 1 , wherein a first signal indicating a wearing or non-wearing of the seat belt and a second signal indicating a door open or close are inputted into the control unit, and the detection module detects an action of the occupant entering or exiting the vehicle according to the first and second signals.

3. A seat belt apparatus comprising:

a tongue plate that is slidably attached to the seat belt;

a buckle to which the tongue plate is inserted and latched; and

a seat belt retractor comprising:

a seat belt winding device for winding up a seat belt by actuation of a motor; and

a control unit that under a predetermined condition repeats a process of stopping the actuation of the motor when an overload of the motor is detected and restarting the actuation of the motor after a lapse of a predetermined time period, the control unit comprises:

a detection module for detecting an action of an occupant entering or exiting a vehicle; and

a determination module that, using criteria, determines whether or not actuation of the motor, when stopped by detection of an overload, is to be restarted;

wherein the criteria when the occupant enters the vehicle is different from the criteria when the occupant exits the vehicle;

wherein the criteria are provided so that the determination module is more likely to determine that the actuation of the motor is not to be restarted when the occupant enters the vehicle as compared to when the occupant exits the vehicle,

wherein the control unit further comprises a clock module for clocking a motor actuating time period from a start to a stop of the actuation of the motor,

wherein, when the occupant exits the vehicle, the determination module determines that the actuation of the motor is not to be restarted when the motor actuating time period is shorter than a predetermined time period a third number of times in a row, and

when the occupant enters the vehicle, the determination module determines that the actuation of the motor is not to be restarted when the motor actuating time period is shorter than the predetermined time period a fourth number of times in a row, the fourth number of times being smaller than the third number of times.

4. A seat belt winding method for repeating, under a predetermined condition, a process of stopping the actuation of a motor, which provides power for winding up a seat belt, when an overload of the motor is detected during the actuation of the motor and restarting the actuation of the motor after a lapse of a predetermined time period, comprising the steps of:

detecting an action of an occupant for entering or exiting the vehicle; and

determining, using criteria, whether or not to restart the actuation of the motor, which is stopped by detection of the overload;

wherein, the criteria for when the occupant enters the vehicle and for when the occupant exits the vehicle are different from each other;

wherein, the criteria are provided so that the determining step is more likely to determine that the actuation of the motor is not to be restart when the occupant enters the vehicle as compared to when the occupant exits the vehicle,

wherein in the determining step, when the occupant exits the vehicle, it is determined that the actuation of the motor is not to be restart when a number of times of starting the actuation of the motor reaches a first number of times, and

when the occupant enters the vehicle, it is determined that the actuation of the motor is not to be restart when the number of times of starting the actuation of the motor reaches a second number of times that is lower than the first number of times.

5. A seat belt winding method as claimed in claim 4 , further comprising a step of clocking the motor actuating time period from a start to a stop of the actuation of the motor,

wherein, in the retry determining step, when the occupant exits the vehicle, it is determined that the actuation of the motor is not to be restart when the motor actuating time period is shorter than a predetermined time period a third number of times in a row, and

when the occupant enters the vehicle, it is determined that the actuation of the motor is not to be restart when the motor actuating time period is shorter than the predetermined time period a fourth number of times in a row;

the fourth number of times being smaller than the third number of times.

6. A seat belt winding method as claimed in claim 4 , wherein in the detecting step, an action of the occupant for entering or exiting the vehicle is detected based on a signal indicating a wearing or non-wearing of the seat belt and a signal indicating a door open or close.