Track error signal detection circuit for optical disk device

Abstract

Abstract PURPOSE:To detect a track error signal, and to suppress the occurrence of offset with a simple constitution by generating a diagonal differential signal and a sum total signal from the outputs of a quadruple detector, deciding the direction of an error from the phase difference between the said two signals, then switching the output. CONSTITUTION:The four outputs of the quadruple light receiving element 8 that receives the reflected light from the medium of an optical disk device are added up to make the total signal Sa, and one of the diagonal two of the said outputs is subtracted from the other to make the diagonal differential signal Sd. Comparators 16, 17 respectively decide whether the total signal Sa and the diagonal differential signal Sd respectively are positive or negative, and a D-flip-flop circuit 18 latches the sign of the diagonal differential signal Sd i.e. the direction of the shifting at the time of rising or ending of the total signal Sa. Thereafter, a sign inverter 19 makes the diagonal differential signal Sd or -Sd depending on the decided direction of shifting. A multiplier 20 multiplies the original waveform signal Sd by the waveform Sd or -Sd after the said sign switching, to generate Sd<2> or -Sd<2>. The characteristic shown by broken lines as waveform (j) which is a track error signal, is obtained, by passing the signal of wave form (j) through a low-pass filter.

Inventors

• 👤 Yasuyuki Ozawa
• 👤 靖之 小沢
• 👤 Akio Nimata
• 👤 彰男 二俣
• 👤 Masaharu Moritsugu
• 👤 森次　政春
• 👤 Akihiko Makita
• 👤 昭彦 蒔田

Bibliographic Details