Storage Technology Corporation Partners Ii

Majeed Abed

Robert P McIntosh

An optical disk storage unit has an access and tracking system with a microprocessor which stores a runout signal representing the eccentricity of the tracks and bands as a function of the rotation of the disk surface. The runout signal is summed with the output of the access and tracking system to compensate for eccentricity as the disk rotates.

Runout compensation for a coarse tracking servo system in an optical

Apparatus and methods are disclosed for acquiring and maintaining focus of a coherent light source used to read and write data in an optical disk data storage device. The system uses a conventional astigmatic focus system in conjunction with a signal processor to detect proximity of focus. After proximity of focus is detected, the signal processor enables a fine focus servo system to maintain focus of the coherent light on the disk surface. The system includes a coherent light source for reading and writing data on the optical disk storage medium, a condenser lens for focusing the coherent light on the recording surface of the disk, a cylindrical lens for passing light reflected from the recording surface, a quad light detector responsive to the reflected light from the cylindrical lens for providing an output signal, a controller responsive to the quad detector output signal for providing a control signal when proximity of focus is detected, and a fine servo system for controlling the position of the condenser lens. The system also includes a method of avoiding a false focus on any transparent overcoat layer placed over the recording surface of the optical disk storage medium.

Focus acquisition and maintenance for optical disk system

An optical disk storage unit has an improved access and tracking system in which a low speed velocity signal is derived from a differentiated position error signal. The output of the differentiator is applied to a blanking circuit which disconnects the steep slope portion of the position error signal from a sample and hold circuit. A medium speed velocity signal is derived from the integral of motor current and a high speed velocity signal is derived by digitally counting the band crossings in the position error signal.

Growing community of inventors

Lafayette, CO, United States of America

Majeed Abed