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US 4,051,529 AGranted
Focus control system with movable mirror
AssigneeSony Corporation
InventorSenri Miyaoka
Life of this patent
Estimating the term…
Abstract
A focus control system for an optical record carrier in which a light beam is reflected by a movable mirror through one objective lens and then directed to the carrier through another objective lens so that the light beam remains focused on the record carrier in spite of fluctuations of the carrier.
Claims12
A focus control system for an optical record carrier having a reflective surface, said system comprising:
- a. a light beam source;
- b. first lens means disposed facing said reflective surface and spaced therefrom along a first optical path section for focusing a light beam from said light beam from source on said reflective surface;
- c. a movable mirror;
- d. second lens means disposed facing said movable mirror and spaced therefrom along a second optical path section;
- e. means for directing an incident light beam from said light beam source onto said movable mirror through said second lens means;
- f. means for directing a light beam reflected from said movable mirror through said second lens means to said reflective surface of said carrier through said first lens means;
- and
- g. means for driving said movable mirror so that the distance between said movable mirror and said second lens means along said second optical path section is controlled in response to the distance between said reflective surface of said carrier and said first lens means along said first optical path section, whereby said directed light beam to said reflective surface remains focused on said reflective surface in spite of fluctuations of said reflective surface.
5 more elements
Dependencies are inferred from the claim text.