Method and system for generating a center error signal in an optical storage system

#The present invention relates to optical media, and more particularly to a method and system for generating a center error signal in an optical storage system.

#The demand for mass data storage continues to increase with expanding use of data processing systems and personal computers. Optical data storage systems are becoming an increasingly popular means for meeting this expanding demand. These optical data systems provide large volumes of relatively low-cost storage that may be quickly accessed.

#For the optical storage system, data on an optical disk is stored in spiral or concentric tracks. A laser beam is directed through a series of optical elements and focused as a beam spot on a surface of the disk. Typically, a coarse carriage, on which is mounted an optical head with an objective lens through which the light beam passes, is moved along a radial path to enable the beam spot to be moved between the inner and the outer tracks of the disk near the inner and outer diameters of the disk. The resolution of the coarse carriage and controlling servo loop is generally sufficient only to permit the light beam to be positioned within a few tracks (such as ±5 tracks) of a desired target track. Consequently, a fine tracking actuator is employed to supplement the coarse carriage by finely controlling the light beam to position and maintain it on a single target track.

#Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

#FIG. 1 is a diagram illustrating an optical storage system in accordance with the present invention.

#FIG. 2 shows a CD track wherein the light beam is centered over the track.

#The present invention provides a method and system for generating a center error signal in an optical storage system. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.

#A method and system for generating a center error signal in an optical storage system is disclosed in the context of a preferred embodiment. Through the use of the method and system in accordance with the present invention, a decrease in manufacturing costs is achieved since very precise and expensive mirrors and/or photo detectors are not needed.

#To more particularly describe the features of the present invention, please refer to FIG. 1. FIG. 1 is a diagram illustrating an optical storage system 100 in accordance with the present invention. The system 100 comprises a compact disk (“CD”) 102, a spindle motor 104, a spindle motor driver 106, a focus error generation circuit 108, a focus actuator driver 110, a tracking error generation circuit 112, and a tracking actuator driver 114. The system 100 further comprises multiple analog to digital converters (“ADCs”) 116, 118, 120, a microprocessor 122, multiple digital to analog converters (“DACs”) 124, 126, 128, an optical pick-up unit (“OPU”) 136, a coarse carriage 140, a lead screw 142, a sledge motor 144, a sledge sensor encoder and related electronics (“sledge sensor”) 146, an encoder disk 147, two receivers 148, 150, a sledge motor driver 152, and a center error generation circuit 154.