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:
Sep. 04, 1990
Filed:
Oct. 13, 1988
Tatsuji Kurogama, Hachioji, JP;
Masanori Kawai, Hachioji, JP;
Koji Matsushima, Akishima, JP;
Mitsuru Watanabe, Hachioji, JP;
Konica Corporation, Tokyo, JP;
Abstract
A method for detecting a focal point uses an optical system which includes a laser diode light source, a beam-splitter prism having three surfaces with one surface perpendicular to luminous flux emanating from a recording medium and another surface inclined relative to the first, an objective lens between the prism and the recording medium, a photodetector, and an apparatus capable of moving the objective lens perpendicular to the recording surface. The method using this apparatus includes the steps of placing the prism so that the incident angle of the flux through the objective lens is less than the emergent angle of the flux from the prism to the photodetector, detecting the intensity of the light, and driving the objective lens in response to an electrical signal.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile