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. 10, 2000
Filed:
Apr. 13, 1999
Jan W Aarts, Eindhoven, NL;
Jan P Baartman, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
An optical scanning device includes an optical lens system for focusing a light beam into a scanning spot on an information carrier. The lens system includes a housing containing a main or objective lens and an auxiliary or solid immersion lens with a ring-shaped holder. The lens combination provides a large numerical aperture, so that the scanning device is suitable for scanning information carriers with a high information density, such as high-density compact discs. The lens system also includes an actuator for displacing the lens system and for displacing the auxiliary lens with respect to the main lens in a direction parallel to an optical axis of the lens system for compensating for spherical aberration in a transparent protection layer of the information carrier. The actuator includes a ring-shaped magnetic closing yoke which is secured to a housing and includes two ring-shaped permanent magnets which, viewed parallel to the optical axis, are secured next to one another to the closing yolk. The magnets are magnetised in mutually opposite radial directions relative to the optical axis. The actuator also includes two ring-shaped electric coils, which are secured to a ring-shaped holder of the auxiliary lens. The coils are arranged, viewed parallel to the optical axis, next to one another and opposite the two magnets, and the coils are wound in mutually opposite directions. In this manner, the actuator of the lens system has a favorable ratio between its dimensions and its electromagnetic force, so that the dimensions and weight of the actuator necessary for obtaining a predetermined electromagnetic force can be limited.