Optical disc recording and/or reproducing apparatus having a buffer memory to accommodate track jumps

A reproducing apparatus for a disc-shaped recording medium which has a disc-shaped transparent base plate, a recording layer provided on said base plate and a protective layer provided on said recording layer, wherein the base plate has a diameter not larger than 64 mm and an address information is previously recorded on said disc-shaped recording medium as a wobbled groove, a recording track is formed according to said wobbled groove at a track pitch of approximately 1.6 .mu.m, and the track has an information recording capacity of not less than 130 Mbytes, said reproducing apparatus comprising:

• rotational driving means for rotationally driving the disc-shaped recording medium at a constant linear velocity;
• an optical head for reading compressed data from said disc-shaped recording medium rotated at a constant linear velocity and producing an output signal;
• an RF circuit for detecting playback signals from an output of said optical head;
• playback decoding means for processing said playback signals from said RF circuit by error correction decoding and by demodulation complementary to modulation performed during recording;
• data expansion means for expanding compressed data from said playback decoding means;
• track jump detecting means supplied with the output signal from the optical head for detecting a signal from the wobbled track, detecting a track jump due to vibration from the signal from the wobbled track, and resetting said optical head to a correct track position after the occurrence of a track jump;
• and
• a buffer memory provided between said playback decoding means and said data expansion means, said buffer memory having a capacity at least sufficient to supply data to said data expansion means corresponding to a playback time which elapses between the occurrence of a track jump of a playback position on said disc-shaped recording medium and a resetting of said playback position of the optical head to a correct track position.

A recording and/or reproducing apparatus for a disc-shaped recording medium which has a disc-shaped transparent base plate, a recording layer provided on said base plate and a protective layer provided on said recording layer, wherein the base plate has a diameter not larger than 64 mm and an address information is previously recorded on said disc-shaped recording medium as a wobbled groove, a recording track is formed according to said wobbled groove at a track pitch of approximately 1.6 .mu.m, and the track has an information recording capacity of not less than 130 Mbytes, the recording and/or reproducing apparatus comprising:

• rotational driving means for detecting a signal from the wobbled groove and rotationally driving the disc-shaped recording medium at a constant linear velocity in accordance with the signal detected from the wobbled groove;
• data compression means for data-compressing an input digital information;
• recording encoding means for processing compressed data from said data compression means by error correction encoding and predetermined modulation;
• recording/reproducing means for recording and reproducing encoded data from said recording encoding means on said disc-shaped recording medium while said disc-shaped recording medium is being rotated by the rotational driving means at a constant linear velocity, the recording/reproducing means including an optical head and means for generating an external magnetic field, the optical head and the means for generating an external magnetic field being positioned to face each other with said disc-shaped recording medium in-between;
• an RF circuit for detecting playback signals from an output signal of said optical head;
• playback decoding means for processing said playback signals from said RF circuit by error correction decoding and by demodulation complementary to modulation performed during recording;
• data expansion means for expanding the compressed data from said playback decoding means;
• track jump detecting means supplied with the output signal from the optical head for detecting a signal from the wobbled track, detecting a track jump due to vibration from the signal from the wobbled track, and resetting said optical head and the means for generating an external magnetic field to a correct track position after the occurrence of a track jump;
• and
• a buffer memory provided between said data compression means and said recording encoding means and between said playback decoding means and said data expansion means, said buffer memory having a capacity at least sufficient during recording to store data from said data compression means corresponding to a recording time which elapses between an occurrence of a track jump of a position of said recording means on said disc-shaped recording medium and a resetting of the optical head and the means for generating an external magnetic field to a correct track position, and during reproducing to supply data to said data expansion means corresponding to a playback time which elapses between the occurrence of a track jump of a playback position on said disc-shaped recording medium and a resetting of said playback position of the optical head to a correct track position.