Back to results
US 6,633,523 B1Granted
Optical memory apparatus and focus servo control method
AssigneeFujitsu Limited
InventorsTakashi Masaki, Toru Ikeda
Life of this patent
Estimating the term…
Abstract
An optical memory apparatus has an offset inserting unit for inserting a predetermined offset to the focus error signal, and a focus servo pull-in determining unit for inserting, when the focus servo control unit executes focus servo pull-in, offset to the focus error signal, detecting level change of the focus error signal and determining success or failure of focus servo pull-in.
Claims32
Optical memory apparatus for conducting focus servo control to maintain constant relative positional relationship between a memory medium and an optical spot, comprising:
- a focus actuator for moving said optical spot relative to said memory medium;
- a driving unit for driving said focus actuator;
- a focus detecting unit for detecting a focus error signal indicating relative positional relationship between said memory medium and said optical spot;
- a focus servo control unit for driving said driving unit based on the focus error signal detected from said focus detecting unit in order to move said focus actuator;
- an offset inserting unit for inserting a predetermined offset to said focus error signal;
- and
- a focus servo pull-in determining unit for detecting level change of said focus error signal where said predetermined offset is inserted to said focus error signal when said focus servo control unit has conducted the focus servo pull-in, and determining success or failure of focus servo pull-in,
- wherein a successful focus servo pull-in is determined if the level change of said focus error signal is an expected value which corresponds to an amount of level change which occurs when such predetermined offset is inserted in said focus error signal.
5 more elements
A focus servo control method to maintain a relative positional relationship between a detected body and an optical spot, comprising at least the steps of:
- detecting a focus error signal indicating the relative positional relationship between said detecting body and said optical spot;
- inserting a predetermined offset to said focus error signal;
- and
- detecting level change of said focus error signal where said predetermined offset is inserted to said focus error signal when focus servo pull-in is conducted to determine success or failure of the focus servo pull-in,
- wherein a successful focus servo pull-in is determined if the level change of said focus error signal is an expected value which corresponds to an amount of level change which occurs when such predetermined offset is inserted in said focus error signal.
2 more elements
Optical memory apparatus for conducting focus servo control to maintain constant relative positional relationship between a memory medium and an optical spot, comprising:
- a focus actuator for moving said optical spot relative to said memory medium;
- a driving unit for driving said focus actuator;
- a focus detecting unit for detecting a focus error signal indicating relative positional relationship between said memory medium and said optical spot;.
- a focus servo control unit for driving said driving unit based on the focus error signal detected from said focus detecting unit in order to move said focus actuator;
- an offset inserting unit for inserting a predetermined offset to said focus error signal;
- and
- a focus servo pull-in determining unit for detecting level change of said focus error signal when said focus servo control unit has conducted the focus servo pull-in, and determining success or failure of focus servo pull-in;
- and
- wherein said focus servo pull-in determining unit compares an integral value of the focus error signal before insertion of said offset and after pull-in of focus servo with an integral value of focus error signal after insertion of offset, in order to detect level change of focus error signals.
6 more elements
Optical memory apparatus for conducting focus servo control to maintain constant relative positional relationship between a memory medium and an optical spot, comprising:
- a focus actuator for moving said optical spot relative to said memory medium;
- a driving unit for driving said focus actuator;
- a focus detecting unit for detecting a focus error signal indicating relative positional relationship between said memory medium and said optical spot;
- a focus servo control unit for driving said driving unit based on the focus error signal detected from said focus detecting unit in order to move said focus actuator;
- an offset inserting unit for inserting a predetermined offset to said focus error signal;
- a focus servo pull-in determining unit for detecting level change of said focus error signal when said focus servo control unit has conducted the focus servo pull-in, and determining success or failure of focus servo pull-in;
- and
- wherein said focus servo pull-in determining unit compares (i) the center value of the positive and negative maximum values of a value obtained by sampling the focus error signal, for a plurality of times, (ii) the focus error signal before insertion of said offset after pull-in of the focus servo with the center value of the positive and negative maximum values of the value obtained by sampling, for a plurality of times, and (iii) the focus error signal after insertion of said offset, in order to detect level change of the focus error signal.
5 more elements
Optical memory apparatus for conducting focus servo control to maintain constant relative positional relationship between a memory medium and an optical spot, comprising:
- a focus actuator for moving said optical spot relative to said memory medium;
- a driving unit for driving said focus actuator;
- a focus detecting unit for detecting a focus error signal indicating relative positional relationship between said memory medium and said optical spot;
- a focus servo control unit for driving said driving unit based on the focus error signal detected from said focus detecting unit in order to move said focus actuator;
- an offset inserting unit for inserting a predetermined offset to said focus error signal;
- a focus.servo pull-in determining unit for detecting level change of said focus error signal when said focus servo control unit has conducted the focus servo pull-in, and determining success or failure of focus servo pull-in;
- and
- wherein said focus servo pull-in determining unit compares (i) the level, after passing a low-pass filter, of the focus error signal before insertion of said offset after pull-in of the focus servo with (ii) the level, after passing the low-pass filter, of the focus error signal after insertion of said offset, in order to detect level change of the focus error signal.
5 more elements
Optical memory apparatus for conducting focus servo control to maintain constant relative positional relationship between a memory medium and an optical spot, comprising:
- a focus actuator for moving said optical spot relative to said memory medium;
- a driving unit for driving said focus actuator;
- a focus detecting unit for detecting a focus error signal indicating relative positional relationship between said memory medium and said optical spot;
- a focus servo control unit for driving said driving unit based on the focus error signal detected from said focus detecting unit in order to move said focus actuator;
- an offset inserting unit for inserting a predetermined offset to said focus error signal;
- a focus servo pull-in determining unit for detecting level change of said focus error signal when said focus servo control unit has conducted the focus servo pull-in, and determining success or failure of focus servo pull-in;
- and
- wherein said focus servo pull-in determining unit detects that the result of adding the level of focus error signal after insertion of said offset to the inserted offset value becomes zero.
5 more elements
Optical memory apparatus for conducting focus servo control to maintain constant relative positional relationship between a memory medium and an optical spot, comprising:
- a focus actuator for moving said optical spot relative to said memory medium;
- a driving unit for driving said focus actuator;
- a focus detecting unit for detecting a focus error signal indicating relative positional relationship between said memory medium and said optical spot;
- a focus servo control unit for driving said driving unit based on the focus error signal detected from said focus detecting unit in order to move said focus actuator;
- an offset inserting unit for inserting a predetermined offset to said focus error signal;
- a focus servo pull-in determining unit for detecting level change of said focus error signal when said focus servo control unit has conducted the focus servo pull-in, and determining success or failure of focus servo pull-in;
- and
- wherein said offset is given by step-by-step addition or subtraction.
5 more elements
Optical memory apparatus for conducting focus servo control to maintain constant relative positional relationship between a memory medium and an optical spot, comprising:
- a focus actuator for moving said optical spot relative to said memory medium;
- a driving unit for driving said focus actuator;
- a focus detecting unit for detecting a focus error signal indicating relative positional relationship between said memory medium and said optical spot;
- a focus servo control unit for driving said driving unit based on the focus error signal detected from said focus detecting unit in order to move said focus actuator;
- an offset inserting unit for inserting a predetermined offset to said focus error signal;
- a focus servo pull-in determining unit for detecting level change of said focus error signal when said focus servo control unit has conducted the focus servo pull-in, and determining success or failure of focus servo pull-in;
- and
- wherein when said offset is inserted, offset is once inserted to any one of the positive or negative sides for success of determination and thereafter offset is then inserted in the opposite polarity to make the second check.
5 more elements
A focus servo control method to maintain a relative positional relationship between a detected body and an optical spot, comprising at least the steps of:
- detecting a focus error signal indicating the relative positional relationship between said detecting body and said optical spot;
- inserting a predetermined offset to said focus error signal;
- detecting level change of said focus error signal when focus servo pull-in is conducted to determine success or failure of the focus servo pull-in;
- and
- comparing (i) an integral value of focus error signal before insertion of said offset after pull-in of focus servo with (ii) an integral value of focus error signal after insertion of offset, in order to detect level change of focus error signals.
2 more elements
A focus servo control method to maintain a relative positional relationship between a detected body and an optical spot, comprising at least the steps of:
- detecting a focus error signal indicating the relative positional relationship between said detecting body and said optical spot;
- inserting a predetermined offset to said focus error signal;
- detecting level change of said focus error signal when focus servo pull-in is conducted to determine success or failure of the focus servo pull-in;
- and
- comparing (i) the center value of the positive and negative maximum values of the value obtained by sampling, for a plurality of times, the focus error signal before insertion of said offset after pull-in of the focus servo, with (ii) the center value of the positive and negative maximum values of the value obtained by sampling, for a plurality of times, the focus error signal after insertion of said offset, in order to detect level change of the focus error signal.
2 more elements
A focus servo control method to maintain a relative positional relationship between a detected body and an optical spot, comprising at least the steps of:
- detecting a focus error signal indicating the relative positional relationship between said detecting body and said optical spot;
- inserting a predetermined offset to said focus error signal;
- detecting level change of said focus error signal when focus servo pull-in is conducted to determine success or failure of the focus servo pull-in;
- and
- comparing (i) the level, after passing a low-pass filter, of the focus error signal before insertion of said offset after pull-in of the focus servo, with (ii) the level, after passing the low-pass filter, of the focus error signal after insertion of said offset, in order to detect level change of the focus error signal.
2 more elements
A focus servo control method to maintain a relative positional relationship between a detected body and an optical spot, comprising at least the steps of:
- detecting a focus error signal indicating the relative positional relationship between said detecting body and said optical spot;
- inserting a predetermined offset to said focus error signal;
- detecting level change of said focus error signal when focus servo pull-in is conducted to determine success or failure of the focus servo pull-in;
- and
- detecting that the result of adding the level of focus error signal after insertion of said offset to the inserted offset value becomes zero.
2 more elements
A focus servo control method to maintain a relative positional relationship between a detected body and an optical spot, comprising at least the steps of:
- detecting a focus error signal indicating the relative positional relationship between said detecting body and said optical spot;
- inserting a predetermined offset to said focus error signal;
- detecting level change of said focus error signal when focus servo pull-in is conducted to determine success or failure of the focus servo pull-in;
- and
- wherein said offset is given by step-by-step addition or subtraction.
2 more elements
A focus servo control method to maintain a relative positional relationship between a detected body and an optical spot, comprising at least the steps of:
- detecting a focus error signal indicating the relative positional relationship between said detecting body and said optical spot;
- inserting a predetermined offset to said focus error signal;
- detecting level change of said focus error signal when focus servo pull-in is conducted to determine success or failure of the focus servo pull-in;
- and
- wherein when said offset is inserted, offset is first inserted to any one of the positive or negative sides for success of determination, and thereafter offset is inserted in the opposite polarity to make a second check.
2 more elements
Dependencies are inferred from the claim text.