The huo - kasusa - bo taimingukontoro - ru device null in the optical type record

摘要

PURPOSE:To inhibit the servo operation for an optical disc in case of reverse loading by inputting simultaneously signals, which are outputted when a reproduced RF signal passing an HPF and a focus error signal reach prescribed discrimination levels respectively, to operate the focus servo. CONSTITUTION:The RF signal obtained by adding all outputs of a 4-divided detector 1 of an optical pickup is amplified by an amplifier 2 and passes an HPF3 and is compared with the voltage of a constant voltage power source 5 by a comparator 4 to output a binary signal (c). Meanwhile, a focus error signal (d) outputted from a focus error signal generator 6 is compared with the voltage of a constant voltage power source 8 by an amplitude level discriminator 7, and a binary signal (e) is outputted from the discriminator 7 when an optical disc is loaded correctly. If the disc is reverse loaded, the peak level of the signal (d) is low, and the signal (e) is not outputted from the discriminator 7. An AND circuit 11 outputs a focus servo turn-on signal when signals (c) and (f) are inputted simultaneously, thus inhibiting the focus servo operation for the reverse loaded optical disc.