Recordable optical recording medium containing preinstalled information, the method of reading the same, and the circuit thereof

A circuit for reading preinstalled information in a recordable optical recording medium for reading the preinstalled information from the recordable optical recording medium that contains preinstalled information, the recordable optical recording medium containing a substrate engraved with a spiral pregroove for providing a tracking servo signal, the track of the pregroove being a slightly wobbled spiral curve, the circuit comprising:

• a band-pass filter, which receives a tracking servo signal and outputs a wobble signal, removing signals in non-wobble bands with the wobble containing a plurality of first waveforms, second waveforms, and third waveforms with same fundamental cycles, the duty cycles of the first waveform, the second waveform and the third waveform being all distinct, with that of the first waveform being 1;
• a phase-lock loop, which outputs a clock generating signal according to the wobble signal;
• a phase corrector, which obtains the clock generating signal and makes a 90-degree phase shift to generate a phase corrected signal;
• an integration and reset circuit, which integrates the wobble signal and resets the wobble signal according to the rising and lower edges of the phase corrected signal, outputting an integrated and reset wobble signal;
• and
• a division circuit, which cuts the integrated and reset wobble into a preinstalled information signal.