Adjustment of tracking servo and focusing servo in optical data recording/reproducing apparatus

A focus offset adjusting device comprising:

• an optical pickup means for emitting a light beam onto a recording medium and for outputting, in response to a reflection from said recording medium, a first and a second signal joining in focusing servo control and tracking servo control, respectively, and a third signal representative of data recorded in said medium;
• a signal generating means for outputting, in response to said first signal and said second signal, a focusing servo error signal assigned to focusing servo control and a tracking servo error signal assigned to tracking servo control;
• a drive means for outputting, in response to said focusing and tracking servo error signals, a first drive current and a second drive current assigned to focusing and tracking, respectively;
• an actuator means for moving said optical pickup means in a focusing direction and a tracking direction in response to said first drive current and said second drive current, respectively;
• and
• an adjusting means operative in response to said second signal which appears immediately after the focus servo control is stated for providing said drive means with a focus offset signal representative of a value of a focus offset, and for determining when a difference between a maximum and minimum of the second signal is approximately at its maximum;
• said drive means being further operative in response to the focus offset signal thus provided to correct the first and second drive currents;
• said adjusting means maintaining, after having determined when the difference is approximately at its maximum, the focus offset signal representative of the value of the focus offset produced when the difference is approximately at its maximum, to thereby minimize the focus offset.

A focus offset adjusting device comprising:

• an optical pickup means for emitting a light beam onto a recording medium and for outputting, in response to a reflection from said recording medium, at first and a second signal joining in focusing servo control and tracking servo control, respectively, and a third signal representative of data recorded in said medium;
• a signal generating means for outputting, in response to said first signal and said second signal, a focusing servo error signal assigned to focusing servo control and a tracking servo error signal assigned to tracking servo control;
• a drive means for outputting, in response to said focusing and tracking servo error signals, a first drive current and a second drive current assigned to focusing and tracking, respectively;
• an actuator means for moving said optical pickup means in a focusing direction and a tracking direction in response to said first drive current and said second drive current, respectively;
• and
• an adjusting means operative in response to said third signal which appears while the tracking servo is effected for providing said drive means with a focus offset signal representative of a value of a focus offset, and for determining when a difference between a maximum and a minimum of the third signal is approximately at its maximum;
• said drive means being further operative in response to the focus offset signal thus provided to correct the first and second drive currents;
• said adjusting means maintaining, after having determined when the difference is approximately at its maximum, the focus offset signal representative to the value of the focus offset produced when the difference is approximately at its maximum, to thereby minimize the focus offset.

A focus offset adjusting device comprising:

• an optical pickup device for emitting a light beam onto a recording medium and for outputting, in response to a reflection from said recording medium, a first and a second signal joining in focusing servo control and tracking servo control, respectively, and a third signal representative of data recorded in said medium;
• a signal generator circuit for outputting, in response to said first signal and said second signal, a focusing servo error signal assigned to focusing servo control and a tracking servo error signal assigned to tracking servo control;
• a drive circuit for outputting, in response to said focusing and tracking servo error signals, a first drive current and a second drive current assigned to focusing and tracking, respectively;
• an actuator for moving said optical pickup device in a focusing direction and a tracking direction in response to said first drive current and said second drive current, respectively;
• and
• an adjusting circuit operative in response to either one of said second signal which appears immediately after the focus servo control is started and said third signal which appears while the tracking servo is effected for providing said drive circuit with a focus offset signal representative of a value of a focus offset, and for determining when a difference between a maximum and a minimum of the one signal is approximately at its maximum;
• said drive circuit being further operative in response to the focus offset signal thus provided to correct the first and second drive currents;
• said adjusting circuit maintaining, after having determined when the difference is approximately at its maximum, the focus offset signal representative of the value of the focus offset produced when the difference is approximately at its maximum, to thereby minimize the focus offset.

A method for adjusting a focus offset of an optical pickup means for emitting a light beam onto a recording medium and sensing a reflection from said recording medium, comprising the steps of:

• producing, in response to a reflection from said recording medium, a first and a second signal joining in focusing servo control and tracking servo control respectively, and a third signal representative of data recorded in said medium;
• generating, in response to said first signal and said second signal, a focusing servo error signal assigned to focusing servo control and a tracking servo error signal assigned to tracking servo control;
• outputting, in response to said focusing and tracking servo error signals, a first drive current and a second drive current assigned to focusing and tracking, respectively;
• moving said optical pickup means in a focusing direction and a tracking direction in response to said first drive current and said second drive current, respectively;
• generating, in response to either one of said second signal which appears immediately after the focus servo control is started and said third signal which appears while the tracking servo is effected, a focus offset signal representative of a value of a focus offset;
• determining when a difference between a maximum and a minimum of the one signal is approximately at its maximum;
• correcting, in response to the focus offset signal, the first and second drive currents;
• and maintaining, after having determined when the difference is approximately at its maximum, to hereby minimize the focus offset.