US 5,499,231 A · Optical disk drive with multiple data layer disk and system for focusing the optical beam

Abstract

An optical disk drive with a multiple data layer optical disk uses computed axial velocity values of the data layers to optimize the interlayer transition of the focused light beam. In the preferred embodiment, the axial velocities of the data layers are computed for a set of radial and angular positions on the data layer surfaces using one of several techniques. The data layer axial velocity values are computed from the measured current values to the voice coil motor focus actuator or from the output of the detector that generates the focus error signal (FES). A routine is run at disk drive startup, or at various times during disk drive operation, to measure the coil current or FES at different radial and angular positions and compute the axial velocity values. The computed axial velocity values are then mapped into memory storage according to addresses corresponding to their radial and angular positions. When it is desired to move the focused light beam from one data layer (the initial or take-off data layer) to another data layer (the final or target data layer) the computed axial velocity values are retrieved for the radial and angular positions nearest the take-off and target sectors on the respective data layers. These velocity values are then used to modify the acceleration profile of the focusing lens so that the focused light beam arrives at the desired position on the target data layer with a velocity close to the target data layer axial velocity.

Claims23

Dependent claims

An optical disk data storage system comprising:

an optical disk comprising a plurality of axially spaced-apart data layers;
a disk motor for rotating the disk about an axis;
a light source;
a lens for generating a focused light beam from the source;
a lens motor connected to the lens for moving the lens in an axial direction generally perpendicular to the data layers, whereby the light beam can be focused to different data layers;
a radial actuator connected to the lens motor for moving the lens motor and connected lens generally radially relative to the disk so the focused light beam can be moved to different radial positions on the data layers;
and
a controller coupled to the lens motor for computing a value representative of an axial velocity of a data layer and for controlling movement of the lens motor in response to the computed axial velocity value;
whereby the focused light beam can be moved from one data layer to arrive at a second data layer regardless of the axial velocity of said second data layer.

6 more elements

An optical disk data storage system comprising:

an optical disk having a central axis generally perpendicular to the disk, the disk comprising first and second axially spaced-apart data layers;
a disk motor for rotating the disk about the central axis;
a light source;
a lens for generating a focused light beam from the source;
a lens motor connected to the lens for moving the lens in an axial direction generally perpendicular to the data layers, whereby the light beam can be focused on the first data layer, moved to the second data layer and focused on the second data layer;
a radial actuator connected to the lens motor for moving the lens motor and connected lens generally radially relative to the disk so the focused light beam can be moved to different radial positions on the data layers;
a microprocessor coupled to the lens motor for generating signals to the lens motor representative of an acceleration profile for the lens to move the light beam from the first data layer to the second data layer, the microprocessor including means for computing values representative of axial velocities of the data layers at a plurality of radial and angular positions on the data layers;
and
a memory storage coupled to the microprocessor for storing a map of the computed axial velocity values according to said radial and angular positions, whereby the microprocessor retrieves the stored axial velocity values and modifies the lens acceleration profile in response to the retrieved axial velocity values when the light beam is to be moved from the first data layer to the second data layer.

6 more elements

An optical disk data storage system comprising:

an optical disk having a central axis generally perpendicular to the disk, the disk comprising first and second axially spaced-apart data layers;
a disk motor for rotating the disk about the central axis;
a light source;
a lens for generating a focused light beam from the source;
a lens motor connected to the lens for moving the lens in an axial direction generally perpendicular to the data layers, whereby the light beam can be focused on the first data layer, moved to the second data layer and focused on the second data layer;
a radial actuator connected to the lens motor for moving the lens motor and connected lens generally radially relative to the disk so the focused light beam can be moved to different radial positions on the data layers;
a detector for receiving light reflected from the data layers for generating a focus error signal representative of the deviation of the focused light beam from a data layer;
a signal level detector coupled to the reflected light detector for determining the times when the focus error signal reaches two different signal levels;
and
a microprocessor coupled to the signal level detector and the lens motor for generating signals to the lens motor representative of an acceleration profile for the lens to move the light beam from the first data layer to the second data layer, the microprocessor including means for computing from the signal level detector output the velocity of the lens relative to the second data layer as the light beam moves from the first data layer to the second data layer, whereby the acceleration profile is modified by the microprocessor in response to said computed relative velocity.

7 more elements

Dependencies are inferred from the claim text.

Optical disk drive with multiple data layer disk and system for focusing the optical beam

Life of this patent

Optical disk drive with multiple data layer disk and system for focusing the optical beam

Life of this patent

Abstract

Claims23