Position controller and position control method of optical system and recording/reproducing apparatus and driving method thereof

A position control method of an optical system for controlling a distance from an optical system for forming a near-field with an optical recording medium and focusing converged light to the optical recording medium to said optical recording medium, including the steps of:

• shortening the distance between said optical system and said optical recording medium from outside to inside a range where said near-field is formed;
• and
• maintaining said distance within said range,
• wherein said distance is shortened in stages from outside to inside the range where said near-field is formed.

A recording/reproducing apparatus comprising:

• a light source;
• an optical system for forming a near-field with an optical recording medium, converging a light from said light source, and focusing it to said optical recording medium;
• an actuator for moving said optical system in a focal direction perpendicularly intersecting a recording surface of said optical recording medium;
• a control circuit for controlling said actuator so as to shorten the distance between said optical system and said optical recording medium from outside to inside the range where said near-field is formed and further maintain it within said range;
• a motor for rotating said optical recording medium at the time of recording information and reproducing information;
• an intensity modulation circuit for modulating a light intensity from said light source in accordance with recording information at the time of recording information;
• and
• a detection circuit for detecting recording information from reflection light reflected on said optical recording medium at the time of recording,
• wherein said control circuit controls said actuator so as to shorten said distance in stages from outside to inside a range where said near-field is formed and maintain it within said range.

A method of driving a recording/reproducing apparatus using an optical system forming a near-field with an optical recording medium to focus converged light on the optical recording medium for recording or reproducing information, including the steps of:

• shortening the distance between said optical system and said optical recording medium from outside to inside a range where said near-field is formed;
• maintaining said distance within said range;
• rotating said optical recording medium;
• detecting recorded information from reflection light reflected at said optical recording medium during rotation at the time of reproducing information;
• and
• supplying modulated light modulated in intensity in accordance with recording information and focusing converged light from said optical system to said optical recording medium during rotation,
• wherein said distance is shortened in stages from outside to inside a range where said near-field is formed.