Write protect switch device

Abstract

A write protect switch device accommodated in a disk drive comprises an arm whose one end is supported by a frame of the disk drive, and a rotatable cam member supported by the other end of the arm, whose abutting end slides on a casing of a disk cartridge, the cam member displacing the other end of the arm in the direction of separating from the frame at the time of insertion of the disk cartridge; fitting into a write protect notch of the casing to displace the arm in the direction of approaching the frame when the abutting end arrives at the position of the notch; turning in the ejection direction of the disk cartridge with the arm kept close to the frame at the time of ejection; and after ejection, returning to the state before insertion of the disk cartridge. The write protect switch device also includes a spring for urging the whole arm inclusive of the cam member toward the frame, another spring for urging the cam member in the direction of rotating the same in the insertion direction of the disk cartridge, and switch means performing its switching action in response to the operation of the arm of approaching and separating from the disk cartridge. The cam member swings about the other end of the arm in response to the insertion/ejection movement of the disk to magnify and convert the amount of recess of the notch into the swing stroke of the arm about its one end.