Yoshiro Nakamatsu
Nakamatsu claims IBM reached licensing agreements with him in the late 1970s. He also claims to have licensed his floppy disk to IBM in 1979, but that the details are "confidential". An IBM spokesman, Mac Jeffery, confirmed that the company did license some of his patents, but claimed they were not for the floppy disk, which he claimed IBM invented on its own. Another IBM spokesman, Brian Doyle, said they licensed 14 patents from Nakamatsu, but also claimed that they do not have anything to do with the floppy disk.
History of the floppy disk
In 1984, IBM introduced the 5.25" high density disk format with its new IBM AT machines. The 5.25" HD drive was essentially a scaled-down 8" drive, using the same rotation speed and bit rate, and it provided almost three times as much storage as the 360k format, but had compatibility issues with the older drives due to the narrower read/write head.