US 5,497,360 AGranted

Optical disc apparatus with accessing using only reference velocity during acceleration and reference and moving velocities during deceleration

AssigneeKabushiki Kaisha Toshiba

InventorsTamane Takahara, Akihiro Kasahara

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Abstract

With this invention, the reference velocity data corresponding to the number of the remaining tracks to the destination target position of the optical head is stored, and on the basis of the reference velocity data, the velocity of the optical head is controlled. The reference velocity data contains the maximum velocity region data and deceleration data for the optical head. The deceleration data is obtained by subtracting the steady-state deviation from the velocity trajectory. The steady-state velocity deviation is obtained from the response characteristic of the optical-head velocity control system. When the optical head is moved, the reference velocity data corresponding to the number of the remaining tracks between the current position of the optical head and the destination target position is read. On the basis of this read-out reference velocity data, a linear motor for driving the optical head is controlled.

An optical disk apparatus reproducing information recorded along tracks formed on an optical disk by accessing a target track on the optical disk, said apparatus comprising:

spot applying means for applying a light beam spot on an arbitrary track in order to reproduce the information from the track;
determining means for determining the number of remaining tracks located between the target track and a track on which the light beam spot is applied;
moving means for moving the spot applying means to move the light beam spot applied by the spot applying means;
detecting means for detecting an actual moving velocity D of the spot applying means moved by the moving means;
acceleration and deceleration control means for controlling a moving velocity of the spot applying means moved by the moving means, in response to a reference velocity which varies in accordance with the remaining track number, the acceleration and deceleration control means, when the spot applying means is located in a decelaration region in which the number of the remaining tracks is small, controlling the moving velocity of the spot applying means to decelerate in response to the actual moving velocity D of the spot applying means and the reference velocity, and when the spot applying means is located in an acceleration region, in which the remaining tracks number is large, controlling the moving velocity of the spot applying means to accelerate in response to only the reference velocity;
first storing means for storing a velocity trajectory curve B which is determined as an object velocity of the spot applying means in response to the remaining track number;
second storing means for storing a specific value C representing a steady-state velocity deviation wherein the reference velocity is smaller than the velocity trajectory curve B by the specific value C;
and
supplying means for supplying to the acceleration and deceleration control means a maximum velocity of the velocity trajectory curve B stored in the first storing means as the reference velocity when the spot applying means is located in the acceleration region, and for supplying to the acceleration and deceleration control means a moving velocity lower than the velocity trajectory curve B by the specific value C stored in the second storing means as the reference velocity, so that the actual moving velocity D of the spot applying means coincides with the velocity trajectory curve B when the spot applying means is located in the deceleration region.

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Abstract

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