Optical recording medium tilt compensation device, tilt compensation method, and optical information recording apparatus

An optical recording medium tilt compensation device, comprising:

• an object lens that condenses light from a light source on a recording surface of an optical recording medium;
• an object lens tilt actuator that controls a tilt of the object lens;
• an object lens tilt sensor that detects the tilt of the object lens;
• a first gain variable unit that amplifies amplitude of an output signal from the object lens tilt sensor;
• an optical recording medium tilt sensor that detects a tilt of the optical recording medium;
• a second gain variable unit that amplifies amplitude of an output signal from the optical recording medium tilt sensor;
• and
• a control unit that controls the tilt of the object lens in accordance with a tilt value from the optical recording medium tilt sensor so that an aberration of the spot condensed on the recording surface is made minimum by driving the object lens tilt actuator;
• wherein
• a variable gain of the tilt of the object lens of the first gain variable unit including the object lens tilt sensor is different from a variable gain of the tilt of the optical recording medium of the second gain variable unit including the optical recording medium tilt sensor.

A method of compensating for tilt in an optical recording medium tilt compensation device including an object lens tilt actuator that controls a tilt of an object lens for condensing light from a light source on a recording surface of an optical recording medium;

• an object lens tilt sensor that detects the tilt of the object lens;
• an optical recording medium tilt sensor that detects a tilt of the optical recording medium;
• and a control unit that controls the tilt of the object lens in accordance with a tilt value from the optical recording medium tilt sensor so that an aberration of the spot condensed on the recording surface is made minimum by driving the object lens tilt actuator, wherein a magnitude of an output signal from the object lens tilt sensor or the optical recording medium tilt sensor is variable, said method comprising the steps of:
• multiplying the tilt output from the object lens tilt sensor by a variable gain, or multiplying the tilt output from the optical recording medium tilt sensor by the variable gain;
• and
• controlling the tilt of the object lens by using the object lens tilt actuator so that a relative tilt becomes zero, said relative tilt being calculated from a difference between the tilt of the object lens multiplied by the variable gain and the tilt of the optical recording medium or from a difference between the tilt of the object lens and the tilt of the optical recording medium multiplied by the variable gain.

An optical information processing apparatus, comprising:

• an optical recording medium tilt compensation device including:
• an object lens that condenses light from a light source on a recording surface of an optical recording medium;
• an object lens tilt actuator that controls a tilt of the object lens;
• an object lens tilt sensor that detects the tilt of the object lens;
• an optical recording medium tilt sensor that detects a tilt of the optical recording medium;
• a control unit that controls the tilt of the object lens in accordance with a tilt value from the optical recording medium tilt sensor so that an aberration of the spot condensed on the recording surface is made minimum by driving the object lens tilt actuator;
• and
• a gain variable unit that changes a magnitude of an output signal from the object lens tilt sensor or the optical recording medium tilt sensor,
• wherein
• said optical information processing apparatus condenses light from a light source on a recording surface of an optical recording medium so as to record or delete data, and detects light transmitting through the optical recording medium or reflected from the optical recording medium by using the photo detector, or detects light condensed in a signal detection optical system by using the photo detector.

An optical information processing apparatus that uses an optical recording medium tilt compensation method of compensating for tilt in an optical recording medium tilt compensation device including an object lens tilt actuator that controls a tilt of an object lens for condensing light from a light source on a recording surface of an optical recording medium;

• an object lens tilt sensor that detects the tilt of the object lens;
• an optical recording medium tilt sensor that detects a tilt of the optical recording medium;
• and a control unit that controls the tilt of the object lens in accordance with a tilt value from the optical recording medium tilt sensor so that an aberration of the spot condensed on the recording surface is made minimum by driving the object lens tilt actuator, wherein a magnitude of an output signal from the object lens tilt sensor or the optical recording medium tilt sensor is variable, said method comprising the steps of:
• multiplying the tilt output from the object lens tilt sensor by a variable gain, or multiplying the tilt output from the optical recording medium tilt sensor by the variable gain;
• and
• controlling the tilt of the object lens by using the object lens tilt actuator so that a relative tilt becomes zero, said relative tilt being calculated from a difference between the tilt of the object lens multiplied by the variable gain and the tilt of the optical recording medium or from a difference between the tilt of the object lens and the tilt of the optical recording medium multiplied by the variable gain,
• wherein
• said optical information processing apparatus condenses light from a light source on a recording surface of an optical recording medium so as to record or delete data, and detect light transmitting through the optical recording medium or reflected from the optical recording medium by using a photo detector, or detects light condensed in a signal detection optical system by using the photo detector.