The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 22, 1989
Filed:
Sep. 16, 1987
Hiroo Ukita, Tokyo, JP;
Yoshitada Katagiri, Tokyo, JP;
Renshi Sawada, Saitama, JP;
Yuuji Uenishi, Saitama, JP;
Yoshihiro Isomura, Tokyo, JP;
Tomoyuki Toshima, Saitama, JP;
Keisuke Mise, Saitama, JP;
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Abstract
A micro optical head, for optically reading and/or writing digital data on a recording medium in which digital data 1 and 0, corresponding to a high reflection factor and a low reflection factor, is composed of a self-coupled semiconductor laser located close to the recording medium. A bias current of the laser is determined so that it is smaller than a first threshold current, in which the medium has a low reflection factor, and is higher than a second threshold current, in which the medium has a high reflection factor. Output light of the laser is either strong stimulated emission light, corresponding to the high reflection factor, or weak spontaneous emission light, corresponding to the low reflection factor. The present head is carried on a flying slider with a spacing length less than several .mu.m which provides a small beam spot of about 1 .mu.m, and has an excellent signal to noise ratio. A photodetector for sensing the output of the laser may be carried on the same semiconductor substrate as that of the laser.