Patent ID: 7174558

Claim:
A memory device for at least one of recording, playback, and erasure of data through the application of an optical head along a memory medium, comprising: a head carnage which moves the optical head along a surface of the memory medium; a carriage lock which is used to prevent movement of said head carriage in response to a specific shock force, said carriage lock utilizing mechanical energy received from said shock force to prevent said movement; and a return member that exerts a biasing force on said carriage lock to automatically return said carriage lock to an unlocked position from a locked position after said shock force subsides and to hold said carriage lock in said unlocked position when no shock force exists, said unlocked position locating said carriage lock entirely outside of a path of movement of said head carriage; wherein said carriage lock is constructed to be able to move between said locked and unlocked positions in direct conjunction with said mechanical energy from said shock force, and wherein a locking force that directly moves said carriage lock into said locked position is greater than said biasing force that holds and returns said carriage lock to said unlocked position.