Patent litigation case study: lemke narrow-gap-head recording patent and Japanese magnetic recording R & D in the 1960s and 1970s

摘要

A patent litigation case relevant to magneticrecording is introduced from technical and historical viewpoint.The patent in question claimed high-density recording using anarrow head gap of less than 0.38 #mu#m. The patentee arguedthat it covered the vector recording technology studied by theinventor, J.U. Lemke. Investigation of the argument in the light ofstudies made by S. Iwasaki and his group, the NHK Technical Lab.and others during the 1960s and 1970s in Japan, reveals thatLemke's patent disclosed nothing that had not already beendiscovered in Japanese research up to that date. The patent wasfinally rejected.