Tracking and focus control system for optical disk apparatus

An optical disk apparatus comprising:

• an irradiating means for irradiating a light beam upon an optical disk having a track including at least a successive groove or a row of pits;
• an information signal photodetector for detecting an information signal from a light reflected by the optical disk;
• an optical element for dividing the reflected light into a plurality of light beams for generating a tracking error signal and a focus error signal, and said light beams being deflected into different directions from each other;
• said optical element dividing the reflected light into four light beams on a cross section of the reflected light by a track line corresponding to a central line of the track and a line perpendicular to the track line;
• photodetecting means for detecting each one of these light beams
• said photodetecting means including four halving photodetectors which are located in focal points of the four divided light beams, and each of which has two detecting portions for each detecting an inner portion and an outer portion of the reflected light,
• a first calculating means for calculating the focus error signal on the basis of outputs from said photodetecting means;
• and
• a second calculating means for calculating a tracking error signal on the basis of the outputs from said photodetecting means when said successive groove or said row of pits are detected;
• wherein said first calculating means calculates the focus error signal by a Foucault method from the outputs of said photodetecting means, and
• said second calculating means includes
• a first tracking error signal generating unit for generating a tracking error signal by a push-pull method;
• a second tracking error signal generating unit for generating a tracking error signal by a heterodyne method;
• a judging means for judging whether the track has a successive groove or only a row of pits;
• and
• a selecting unit for selecting a signal from said first tracking error signal generating unit when the track includes a successive groove, and selecting a signal from said second tracking error signal generating unit when the track includes only a row of pits, on the basis of a judgment signal from said judging means.

An optical disk apparatus comprising:

• an irradiating means for irradiating a light beam upon an optical disk having a track including at least a successive groove or a row of pits;
• an information signal photodetector for detecting an information signal from a light reflected by the optical disk;
• an optical element for dividing the reflected light into a plurality of light beams for generating a tracking error signal and a focus error signal, said light beams being deflected into different directions from each other;
• said optical element dividing the reflected light into three light beams on a cross section of the reflected light in a track line direction corresponding to a direction line of the track, further dividing the three light beams into two in a direction perpendicular to the track line direction, and deflecting the six divided light beams into different directions from each other,
• photodetecting means for detecting each one of said light beams, said photodetecting means including:
• pp-photodetectors located in focal points of the two divided light beams in the center position of the track line direction of the six divided light beams;
• and
• halving photodetectors located at focal points of the other four light beams,
• a first calculating means for calculating the focus error signal on the basis of outputs from said photodetecting means;
• and
• a second calculating means for calculating a tracking error signal on the basis of the outputs from said photodetecting means when said successive groove or said row of pits are detected,
• wherein said first calculating means calculates the focus error signal by a Foucault method from the outputs of said photodetecting means, and
• said second calculating means includes
• a first tracking error signal generating unit for generating a tracking error signal by a push-pull method;
• a second tracking error signal generating unit for generating a tracking error signal by a heterodyne method;
• a judging means for judging whether the track has a successive groove or only a row of pits;
• and
• a selecting unit for selecting a signal from said first tracking error signal generating unit when the track includes a successive groove, and selecting a signal from said second tracking error signal generating unit when the track includes only a row of pits, on the basis of a judgment signal from said judging means.

An optical disk apparatus comprising:

• an irradiating means for irradiating a light beam upon an optical disk having a track including at least a successive groove or a row of pits;
• an information signal photodetector for detecting an information signal from a light reflected by the optical disk;
• an optical element for dividing the reflected light into a plurality of light beams for generating a tracking error signal and a focus error signal, and deflecting these light beams into different directions from each other;
• said optical element dividing the reflected light into two first divided light beams located at the sides of a track line corresponding to a central line of the track on a cross section of the reflected light, and two second divided light beams for generating the focus error signal, the divided light beams being deflected into different directions from each other, the reflected light being partially transmitted as 0-order light;
• photodetecting means for detecting each one of said light beams, said photodetecting means including:
• two first halving photodetectors located in far fields of said first divided light beams;
• and
• two second halving photodetectors which are located at focal points of said second divided light beams, and each of which has two detecting portions for each detecting an inner portion and an outer portion of the reflected light, and
• said information signal photodetector receiving the 0-order light,
• a first calculating means for calculating the focus error signal on the basis of outputs from said photodetecting means;
• and
• a second calculating means for calculating a tracking error signal on the basis of the outputs from said photodetecting means when said successive groove or said row of pits are detected;
• wherein said first calculating means calculates the focus error signal by a Foucault method from the outputs of said photodetecting means, and
• said second calculating means includes
• a first tracking error signal generating unit for generating a tracking error signal by a push-pull method;
• a second tracking error signal generating unit for generating a tracking error signal by a heterodyne method;
• a judging means for judging whether the track has a successive groove or only a row of pits;
• and
• a selecting unit for selecting a signal from said first tracking error signal generating unit when the track includes a successive groove, and selecting a signal from said second tracking error signal generating unit when the track includes only a row of pits, on the basis of a judgment signal from said judging means.

An optical disk apparatus comprising:

• an irradiating means for irradiating a light beam upon an optical disk having a track including at least a successive groove or a row of pits;
• an information signal photodetector for detecting an information signal from a light reflected by the optical disk;
• an optical element for dividing the reflected light into a plurality of light beams for generating a tracking error signal and a focus error signal, and deflecting these light beams into different directions from each other;
• said optical element dividing the reflected light into four light beams on a cross section of the reflected light by a track line corresponding to a central line of the track and a line perpendicular to the track line, deflecting the divided light beams into different directions from each other, and partially transmitting the reflected light as 0-order light, said information signal photodetector receiving the 0-order light;
• photodetecting means for detecting each one of said light beams, said photodetecting means including:
• four halving photodetectors which are located in focal points of the four divided light beams, each of which has two detecting portions for each detecting an inner portion and an outer portion of the reflected light;
• a first calculating means for calculating the focus error signal on the basis of outputs from said photodetecting means;
• and
• a second calculating means for calculating a tracking error signal on the basis of the outputs from said photodetecting means when said successive groove or said row of pits are detected;
• wherein said first calculating means calculates the focus error signal by a Foucault method from the outputs of said photodetecting means;
• and
• said second calculating means includes
• a first tracking error signal generating unit for generating a tracking error signal by a push-pull method;
• a second tracking error signal generating unit for generating a tracking error signal by a heterodyne method;
• a judging means for judging whether the track has a successive groove or only a row of pits;
• and
• a selecting unit for selecting a signal from said first tracking error signal generating unit when the track includes a successive groove, and selecting a signal from said second tracking error signal generating unit when the track includes only a row of pits, on the basis of a judgment signal from said judging means.

An optical disk apparatus comprising:

• an irradiating means for irradiating a light beam upon an optical disk having a track including at least a successive groove or a row of pits;
• an information signal photodetector for detecting an information signal from a light reflected by the optical disk;
• an optical element for dividing the reflected light into a plurality of light beams for generating a tracking error signal and a focus error signal, and deflecting these light beams into different directions from each other;
• said optical element dividing the reflected light into three light beams on a cross section of the reflected light in a track line direction corresponding to a direction line of the track and the three light beams to be divided into two in a direction perpendicular to the track line direction, deflecting the six divided light beams into different directions from each other, and partially transmitting the reflected light as 0-order light, said information signal photodetector receiving the 0-order light;
• photodetecting means for detecting each one of these light beams, said photodetecting means including:
• pp-photodetectors located in focal points of the two divided light beams in the center position of the track line direction, of the six divided light beams;
• and
• halving photodetectors located at focal points of the rest four light beams;
• a first calculating means for calculating the focus error signal on the basis of outputs from said photodetecting means;
• and
• a second calculating means for calculating a tracking error signal on the basis of the outputs from said photodetecting means when said successive groove or said row of pits are detected;
• wherein said first calculating means calculates the focus error signal by a Foucault method from the outputs of said photodetecting means;
• and
• said second calculating means includes
• a first tracking error signal generating unit for generating a tracking error signal by a push-pull method;
• a second tracking error signal generating unit for generating a tracking error signal by a heterodyne method;
• a judging means for judging whether the track has a successive groove or only a row of pits;
• and
• a selecting unit for selecting a signal from said first tracking error signal generating unit when the track includes a successive groove, and selecting a signal from said second tracking error signal generating unit when the track includes only a row of pits, on the basis of a judgment signal from said judging means.

An optical disk apparatus comprising:

• an irradiating means for irradiating a light beam upon an optical disk having a track including at least a successive groove or a row of pits;
• an information signal photodetector for detecting an information signal from a light reflected by the optical disk;
• a prism for dividing the reflected light into a plurality of four light beams for generating a tracking error signal and a focus error signal, and deflecting these light beams into different directions from each other;
• photodetecting means for detecting each one of these light beams;
• a first calculating means for calculating the focus error signal on the basis of outputs from said photodetecting means;
• and
• a second calculating means for calculating a tracking error signal on the basis of the outputs from said photodetecting means when said successive groove or said row of pits are detected;
• wherein said first calculating means calculates the focus error signal by a Foucault method from the outputs of said photodetecting means, and
• said second calculating means includes
• a first tracking error signal generating unit for generating a tracking error signal by a push-pull method;
• a second tracking error signal generating unit for generating a tracking error signal by a heterodyne method;
• a judging means for judging whether the track has a successive groove or only a row of pits;
• and
• a selecting unit for selecting a signal from said first tracking error signal generating unit when the track includes a successive groove, and selecting a signal from said second tracking error signal generating unit when the track includes only a row of pits, on the basis of a judgment signal from said judging means.