Method of vertical deviation disc detection

Abstract

A method is provided to detect whether vertical deviation occurs as an optical disc spins in an optical disc player having a pickup head pre-installed in a balanced position at a focal distance. When moving towards and away from the balanced position, the pickup head generates a focus error signal with an S-curve. According to an input control signal, a focus actuator actuates the pickup head to keep it substantially at the focal distance. When the pickup head is not focused, the waveform of the input control signal is designed to actuate the pickup head back and forth within a predetermined range to generate the focus error signal with S-curves. Zero crossing points of S-curves are identified and input control values in the input control signal are obtained accordingly. The variation of the input control values is calculated, and whether vertical deviation occurs is determined by a predetermined procedure.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a detection method, and more particularly, to a method for detecting whether vertical deviation of an optical disc occurs while the optical disc is spinning in an optical disc player or an optical disc writer. [0003] 2. Description of the Prior Art [0004] Vertical deviation refers to the wobbling of an optical disc, along the perpendicular direction of the spinning level that the optical disc is spinning on, while the optical disc is spinning in the optical disc player or optical disc writer. Vertical deviation causes data reading to be unstable, writing quality to be inconsistent, and noise to be produced while the machine is operating. [0005] Vertical deviation usually results from poor quality of the optical disc; this kind of undesired disc is called vertical deviation disc. In the field of disc manufacturing, there are many related technologies to prevent vertical deviation disc...

AI Technical Summary

Benefits of technology

The present invention provides a method for detecting vertical deviation in optical disc players or writers. This helps to improve the stability and reduce noise when writing or reading data on the disc. The method involves detecting the variation in the input control values corresponding to the zero-crossing points of S-curves in the focus error signal. This variation is caused by the pickup head approaching and moving away from the optical disc. The method can be used in both optical disc players and writers. The technical effect of the invention is to provide a reliable and efficient means for detecting vertical deviation discs, which can help to improve the overall performance and reliability of optical disc players and writers.

Problems solved by technology

The pickup head is predeterminedly installed in a balanced position at a focal distance from the optical disc for reading data on the optical disc and generates a focus error signal.

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