Method and disc reading device for detecting unbalanced disc

A disc reading apparatus for determining an unbalance status of a disc, the disc reading apparatus comprising:

• a first sensor for detecting a first parameter when the disc reading apparatus driving the disc at a predetermined voltage;
• a second sensor for detecting a second parameter when the disc reading apparatus driving the disc at the predetermined voltage
• a cache memory for recording the detected second parameter as a first corresponding value when the first parameter is detected as being equal to a first predetermined value, and for recording the detected second parameter as a second corresponding value when the first parameter is detected as being equal to a second predetermined value;
• a data table having a standard difference corresponding to an unbalance-free disc and a plurality of reference differences respectively corresponding to a plurality of unbalanced discs;
• and
• a calculating unit for calculating a difference between the first corresponding value and the second corresponding value and determining the unbalance status of the disc by comparing the calculated difference to the standard difference and the reference differences in the data table.