Disc drive apparatus, and method for recognizing CD and DVD

Method for recognizing type (CD;

• DVD) of an optical disc, wherein:
• a light beam (32) is generated, directed towards the optical disc (2), and caused to reflect from the optical disc (2), wherein the light beam passes an optical lens (34);
• the reflected light beam (32d) is received by an optical detector (35);
• an output signal (SR) from said optical detector (35) is received;
• said optical lens (34) is caused to move axially with respect to said optical disc (2);
• said output signal (SR) is analyzed to detect when (P1;
• tS) a focus point of said light beam (32) substantially coincides with a surface of the optical disc (2) and to detect when (P2;
• tL) said focus point of said light beam (32) substantially coincides with an information layer of the optical disc (2);
• wherein a thickness time Δt is calculated in accordance with the formula:
• Δt=tL−tS
• tS being the time of coincidence with said disc surface;
• tL being the time of coincidence with said information layer;
• wherein, for each expected disc type (CD;
• DVD), a corresponding disc type counter (N(CD);
• N(DVD)) is defined and a corresponding average type thickness time (ΔtAV(CD);
• ΔtAV(DVD)) is defined;
• wherein, after a new disc (2) is inserted (step 301) in a disc drive (1), the values of all disc type counters are compared with a predefined minimum value (NMIN);
• wherein, if all disc type counters have a counter value below the predefined minimum value (NMIN), the type of disc is determined by any suitable method, for instance a traditional method (100);
• and wherein, on recognition of a specific disc type, the value of the corresponding disc type counter is increased and the value of the corresponding average type thickness time is updated.