Floppy disk drive unit with mounting plate between carriage and lower magnetic head

A floppy disk drive unit comprising:

• floppy disk supporting means for rotatably supporting a recording medium disk in a floppy disk cartridge having a shutter slidably covering a window opening for accessing said recording medium, the window opening having a predetermined width in a window width direction and the recording medium disk having tracks arranged in a radial direction;
• a head cartridge assembly which is movable in the radial direction in which the tracks of said recording medium disk are arranged including:
• lower and upper magnetic heads;
• a carriage and an upper arm, said upper arm and said carriage being symmetrically arranged with respect to a center plane of said floppy disk cartridge which is parallel to a rotating plane of said recording medium disk, supporting said lower and upper magnetic heads at their tips, respectively, and pinching said recording medium disk with said lower and upper magnetic heads when the floppy disk cartridge is loaded into the floppy disk drive, said lower and upper magnetic heads having a common head width;
• and
• a mounting plate between said lower magnetic head and said, carriage having a predetermined constant thickness and a predetermined width in a direction parallel to the window width direction when the floppy disk cartridge is loaded into the floppy disk drive, which is greater than the head width of said lower magnetic head and smaller than the window opening width, wherein
• said upper and lower magnetic heads are of a common part type for interchangeability,
• the upper and lower magnetic heads have a same height in a direction perpendicular to said rotating plane, and
• said lower magnetic head is fixed on said carriage through said mounting plate to effect penetration of said lower magnetic head to said recording medium disk toward said upper magnetic head from said rotating plane by said predetermined constant thickness, when the floppy disk cartridge is loaded into the floppy disk drive and provide a fixed orientation of said lower magnetic head with respect to said recording medium disk.