Patent ID: 6826133
Filing Date: 2004-11-30
Classification: G11B

Abstract:
An optical information recording/reproducing apparatus comprising:an optical pickup means for making a light beam emitted from a light source incident on a recording medium via a two-group objective lens so as to record or reproduce optical information on or from said recording medium, said two-group objective lens including a first lens disposed at a first position facing said recording medium and a second lens disposed a preset distance from the first position also facing said recording medium at a second position further from the recording medium than said first position, said first and second lenses having a common optical axis therebetween; a reproducing signal detecting means for providing reproducing signals from light received from the recording medium after passage through the pickup means; a moving means for repeatedly moving at least one of said first lens and said second lens back and forth between two end positions along the common optical axis respectively nearer to and farther from the record medium, with each movement between the two end positions occurring over corresponding equal periods of time; and a control means for performing, upon a focusing operation after start up of focus control, a positional adjustment of said at least one of said first lens and said second lens to adjust the distance there between on the basis of changes in the reproducing signals obtained at one or more positions of said at least one of said first lens and said second lens during the repeated movement thereof by said moving means.