A new optical parts driving mechanism in an optical information reader is provided. In general, the reader reads information contained in an information recording medium such as a disc having a driving mechanism axially extending in the center thereof. The optical parts driving mechanism has a lens holder adapted to travel parallel to the disc and carrying an objective at a portion substantially c...

A magnetic disk cartridge comprises a case rotatably housing a magnetic disk, and a shutter slidably fitted onto the case for opening and closing window sections provided in the case for insertion of a magnetic head. The shutter is always urged by a spring to close the window sections. At least one end of the spring is secured to an engagement member having approximately cylindrical protrusions wh...