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:
Oct. 15, 1985
Filed:
Jul. 22, 1982
Fumiaki Henmi, Atsugi, JP;
Yoshio Aoki, Tokyo, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical information recording and reproducing apparatus for recording and reproducing an information signal on and from a recording medium, respectively, having a recording track, and which includes a beam generator, having a laser, for generating a primary beam and first and second secondary beams of light arranged substantially in the same direction as the track on the recording medium, a focussing lens for focusing the primary beam and first and second secondary beams of light on the recording medium, and a detecting device having a primary photodetector for detecting a reflected primary beam from the recording medium and first and second secondary photodetectors for detecting reflected first and second secondary beams from the recording medium. Additionally the apparatus includes a beam intensity control device for controlling the intensity of at least the primary light beam such that high and low intensities of at least the primary beam are sufficient to create and prevent indicia in the recording medium, respectively, in accordance with the information signal when the apparatus is in a recording mode and for controlling the intensity of at least the primary beam such that a substantially constant intensity is maintained in at least the primary beam to prevent indicia from being formed in the recording medium when said apparatus is in a reproducing mode. The apparatus also includes a focussing control device for controlling the position of the focussing lens by using the amplified difference between the outputs of the first and second secondary photodetectors when the apparatus is in a recording mode, and a position control device for controlling the tracking of the primary beam on the recording track in response to the amplified difference between the outputs of the first and second secondary photodetectors when the apparatus is in a reproducing mode.