Focus position control apparatus, optical disc apparatus using the same, and focus position control method

A focus position control apparatus for control of a focus position of an optical beam, the apparatus comprising:

• an error signal generation unit configured to generate, based on an output signal from an optical head configured to irradiate an optical disc in which a track is formed on a recording surface with an optical beam to record or reproduce data, an error signal indicating an amount of a shift of a focus position of the optical beam from a desired position;
• a first control unit configured to generate, based on the error signal, a first control signal for controlling the focus position of the optical beam to a desired position;
• a second control unit configured to generate, when driving of the optical head based on the error signal is not performed, a second control signal for controlling the focus position of the optical beam to a desired position;
• a rotation synchronizing signal generation unit configured to generate a clock signal synchronized with a rotation of the optical disc;
• first and second memory units each being configured to sequentially store, as memory data, a control signal for controlling the focus position of the optical beam to a desired position in synchronization with the clock signal at an associated one of clock addresses whose one round is completed as the optical disc rotates once;
• first and second memory data output units each being configured to sequentially read the memory data stored in an associated one of the first and second memory units in synchronization with the clock signal;
• a phase correction unit configured to correct, when each of the first and second memory data output units reads the memory data from an associated one of the first and second memory units, a phase shift between a clock address for reading and a clock address for storing;
• a control operation switch configured to receive the first and second control signals and selectively output one of the first control signal and the second control signal so that when the driving of the optical head based on the error signal is to be performed, the first control signal is output, and otherwise, the second control signal is output;
• and
• an adding unit configured to add an output signal of each of the first and second memory data output units to an output signal of the control operation switch to generate the control signal,
• wherein
• the phase correction unit corrects the phase shift both when the driving of the optical head based on the error signal is performed and when the driving is not performed,
• at least one of the first and second memory data output units is operated even when the driving of the optical head based on the error signal is not performed, and
• when the driving of the optical head based on the error signal is not performed, input of the control signal to each of the first and second memory units is blocked, and connection of each of the first and second memory data output units with the adding unit is maintained to control the focus position of the optical beam using the control signal obtained by adding the memory data stored in each of the first and second memory units to the second control signal.

A focus position control apparatus for control of a focus position of an optical beam, the apparatus comprising:

• an error signal generation unit configured to generate, based on an output signal from an optical head configured to irradiate an optical disc in which a track is formed on a recording surface with an optical beam to record or reproduce data, an error signal indicating an amount of a shift of a focus position of the optical beam from a desired position;
• a first control unit configured to generate, based on the error signal, a first control signal for controlling the focus position of the optical beam to a desired position;
• a second control unit configured to generate, when driving of the optical head based on the error signal is not performed, a second control signal for controlling the focus position of the optical beam to a desired position;
• a rotation synchronizing signal generation unit configured to generate a clock signal synchronized with a rotation of the optical disc;
• a memory unit configured to sequentially store, as memory data, a control signal for controlling the focus position of the optical beam to a desired position in synchronization with the clock signal at an associated one of clock addresses whose one round is completed as the optical disc rotates once;
• first and second memory data output units each being configured to sequentially read the memory data stored in the memory unit in synchronization with the clock signal;
• a phase correction unit configured to correct, when each of the first and second memory data output units reads the memory data from the memory unit, a phase shift between a clock address for reading and a clock address for storing;
• a control operation switch configured to receive the first and second control signals and selectively output one of the first control signal and the second control signal so that when the driving of the optical head based on the error signal is to be performed, the first control signal is output, and otherwise, the second control signal is output;
• and
• an adding unit configured to add an output signal of each of the first and second memory data output units to an output signal of the control operation switch to generate the control signal,
• wherein
• the phase correction unit corrects the phase shift both when the driving of the optical head based on the error signal is performed and when the driving is not performed,
• at least one of the first and second memory data output units is operated even when the driving of the optical head based on the error signal is not performed, and
• when the driving of the optical head based on the error signal is not performed, input of the control signal to the memory unit is blocked, and connection of each of the first and second memory data output units with the adding unit is maintained to control the focus position of the optical beam using the control signal obtained by adding the memory data stored in the memory unit to the second control signal.

A focus position control method for control of a focus position of an optical beam, the method comprising:

• generating, based on an output signal from an optical head configured to irradiate an optical disc in which a track is formed on a recording surface with an optical beam to record or reproduce data, an error signal indicating an amount of a shift of a focus position of the optical beam from a desired position;
• generating, based on the error signal, a first control signal for controlling the focus position of the optical beam to a desired position;
• generating, when driving of the optical head based on the error signal is not performed, a second control signal for controlling the focus position of the optical beam to a desired position;
• generating a clock signal synchronized with a rotation of the optical disc;
• sequentially storing, as memory data, a control signal for controlling the focus position of the optical beam to a desired position in synchronization with the clock signal at an associated one of clock addresses whose one round is completed as the optical disc rotates once;
• sequentially reading the stored memory data in synchronization with the clock signal;
• correcting, when the stored memory data is read, a phase shift between a clock address for reading and a clock address for storing;
• adding, when the driving of the optical head based on the error signal is to be performed, the read memory data to the first control signal to control the focus position of the optical beam based on a result of the adding;
• and
• stopping, when the driving of the optical head based on the error signal is not performed, storing the control signal as the memory data and adding the read memory data to the second control signal to control the focus position of the optical beam based on a result of the adding.