METHOD AND APPARATUS FOR DETECTING CRACKS IN AN OPTICAL RECORD CARRIER

摘要

The present invention relates to a reading apparatus and to a corresponding reading method for reading data from, and detecting cracks in, an optical record carrier (10). To achieve that a crack in the optical record carrier can be detected with a high reliability so that appropriate measures can be taken, the apparatus comprises a reading unit (14, 15) for reading data from said record carrier by use of a radiation beam and for generating a data signal (RF), a servo error detection unit (16) for tracking a data track on the record carrier and for generating a tracking error signal (TE) and a focus error signal (FE), a control unit (19) for controlling the axial and radial positions of the read-out spot on the record carrier by use of a focus control signal (FA) and a radial control signal (RA), and a crack detection unit (21) for determining whether there is a crack in the record carrier by checking whether the focus error signal (FE) and/or the tracking error signal (TE) show a significant peak, and whether the focus control signal (FA) and/or the radial control signal (RA) show a significant step change.