Patent ID: 8047733

Claim:
A blade drive device comprising: a board having a shutter opening; a blade for adjusting an amount of light entering the shutter opening; and a transmitting member for transmitting a drive force to the blade, wherein: the transmitting member includes a drive pin swinging about a given support point; the blade has a first cam slot engaged with the drive pin and the blade swings in a rotating manner about a given support point in response to a swinging of the drive pin; the first cam slot includes a first permitting area and a first restricting area; the blade is permitted to swing about the given support point when the drive pin is located in the first permitting area; and the blade is restricted from swinging about the given support point when the drive pin is located in the first restricting area, wherein: when the drive pin is located in the first restricting area and swings, the drive pin escapes from the first restricting area; and when the drive pin is located in the first restricting area and an external force is applied to the blade, the drive pin is maintained in the first restricting area.