Tracking servo operating method, tracking servo apparatus and optical disk device provided with same

A tracking servo apparatus comprising:

• a light source to apply a beam spot on an optical disk on which a track is formed;
• a light receiving unit having a multi-divided photodetector comprising a first photo-detecting portion and a second photo-detecting portion being mounted in a manner so as to be divided right and left relative to a circumferential direction of said optical disk to produce a first high frequency signal by having said first photo-detecting portion receive first feedback light from said optical disk and a second high frequency signal by having said second photo-detecting portion receive second feedback light from said optical disk and to produce a high frequency differential signal by calculating a difference between the produced first high frequency signal and the produced second high frequency signal and to produce a tracking error signal based on, at least, the produced high frequency differential signal;
• a controlling unit to binarize said tracking error signal fed from said light receiving unit and to extract a tracking error edge signal indicating an edge of rising and falling of the binarized tracking error signal and, after having filtered a band of each of said first and second high frequency signals fed from said light receiving unit, to binarize the filtered signals and to produce, when the binarized first and second high frequency signals are at a specified same level, a control signal to start a servo operation in response to said tracking error edge signal;
• a driver to produce a driving signal according to said control signal;
• and
• an actuator to move said beam spot according to said driving signal fed from said driver,
• wherein control is exerted so that an operation of pulling in a tracking servo is performed in response to said tracking error edge signal.

A tracking servo apparatus comprising:

• a light source to apply a beam spot on an optical disk on which a track is formed;
• a light receiving means having a multi-divided photodetector comprising a first photo-detecting portion and a second photo-detecting portion being mounted in a manner so as to be divided right and left relative to a circumferential direction of said optical disk to produce a first high frequency signal by having said first photo-detecting portion receive first feedback light from said optical disk and a second high frequency signal by having said second photo-detecting portion receive second feedback light from said optical disk and to produce a high frequency differential signal by calculating a difference between the produced first high frequency signal and the produced second high frequency signal and to produce a tracking error signal based on, at least, the produced high frequency differential signal;
• a controlling means to binarize said tracking error signal fed from said light receiving means and to extract a tracking error edge signal indicating an edge of rising and falling of the binarized tracking error signal and, after having filtered a band of each of said first and second high frequency signals fed from said light receiving means, to binarize the filtered signals and to produce, when the binarized first and second high frequency signals are at a specified same level, a control signal to start a servo operation in response to said tracking error edge signal;
• a driver to produce a driving signal according to said control signal;
• and
• an actuator to move said beam spot according to said driving signal fed from said driver,
• whereby control is exerted so that an operation of pulling in a tracking servo is performed in response to said tracking error edge signal.

An optical disk device provided with a tracking servo apparatus comprising:

• a light source to apply a beam spot on an optical disk on which a track is formed;
• a light receiving unit having a multi-divided photodetector comprising a first photo-detecting portion and a second photo-detecting portion being mounted in a manner so as to be divided right and left relative to a circumferential direction of said optical disk to produce a first high frequency signal by having said first photo-detecting portion receive first feedback light from said optical disk and a second high frequency signal by having said second photo-detecting portion receive second feedback light from said optical disk and to produce a high frequency differential signal by calculating a difference between the produced first high frequency signal and the produced second high frequency signal and to produce a tracking error signal based on, at least, the produced high frequency differential signal;
• a controlling unit to binarize said tracking error signal fed from said light receiving unit and to extract a tracking error edge signal indicating an edge of rising and falling of the binarized tracking error signal and, after having filtered a band of each of said first and second high frequency signals fed from said light receiving unit, to binarize the filtered signals and to produce, when the binarized first and second high frequency signals are at a specified same level, a control signal to start a servo operation in response to said tracking error edge signal;
• a driver to produce a driving signal according to said control signal;
• and
• an actuator to move said beam spot according to said driving signal fed from said driver,
• whereby control is exerted so that an operation of pulling in a tracking servo is performed in response to said tracking error edge signal.