Optical data reading apparatus having means for detecting data degradation resulting from dust coverng the optical pick up head

DETAILED DESCRIPTION It is, therefore, an object of the present invention to provide an optical data reading apparatus which is able to warn of data degradation occurring in an optical data reading apparatus caused by dust covering the optical pickup head of the optical data reading apparatus.
In order to achieve the above object, an optical data reading apparatus according to one aspect of the present invention includes an optical pickup head for transducing an optical signal from the optical record disc to an electrical signal, a detector for detecting the level of the electrical signal, a source for supplying a reference signal representative of a minimum acceptable level for the electrical signal, a comparator for comparing the level of the electrical signal and the reference signal and outputting a comparison signal when the level of the electrical signal is less than the reference signal and a warning device responsive to the comparison signal to indicate that the level of the electrical signal is below the minimum acceptable level.
An optical data reading apparatus for reading data stored in an optical record disc according to another aspect of the present invention includes an optical pickup head for transducing an optical signal from the optical record disc to an electrical signal, a decoder for decoding a PCM data from the electrical signal, a detector for detecting the data error rate of the PCM data, a source for supplying a reference signal representative of a maximum acceptable data error rate, a comparator for comparing the data error rate of the PCM data and the reference signal and outputting a comparison signal when the data error rate of the PCM data exceeds the reference signal and a warning device responsive to the comparison signal to indicate that the data error rate of the PCM data is above the maximum acceptable data error rate.
Additional objects and advantages of the present invention will be apparent to persons skilled in the art from a study of the following description and the accompanying drawings, which are hereby incorporated in and constitute a part of this specification