Method and apparatus for optically recording and reproducing information

A method of renewing information prewritten on an optical disc having guide grooves each divided into a plurality of sectors, said disc also having a file region for recording information therein and a directory region for recording a directory of said file region therein, said file region including a plurality of said sectors, comprising the steps of:

• (a) searching a directory of a file carrying a disignated data to be renewed;
• (b) reading out said data to renew the same;
• (c) storing said directory in a memory;
• (d) erasing said data prewritten in said file by irradiating a laser light beam modulated by a predetermined superposing writing signal, which is a d.c. or a.c. signal having a constant waveform, on a sector or sectors corresponding to said file;
• (e) searching the last position of data prewritten on said disc, such that a sector or sectors whose contents were erased are detected to be skipped;
• (f) writing the renewed data in an unused region which follows said last position;
• (g) renewing the directory stored in said memory so that a new directory designates the position where said renewed data has been written;
• (h) searching the last position of directories which are prewritten in said directory region;
• and
• (i) writing said new directory at an unused region in said directory region which follows said last position of directories.

A method of renewing information prewritten on an optical disc having guide grooves each divided into a plurality of sectors, said disc also having a file region for recording information therein and a directory region for recording a directory of said file region therein, said file region including a plurality of said sectors, comprising the steps of:

• (a) searching a directory of a file carrying a designated data to be renewed;
• (b) reading out said data to renew the same;
• (c) storing said directory in a memory;
• (d) erasing said directory prewritten in said directory region by irradiating a laser light beam modulated by a predetermined superposing writing signal, which is a d.c. or a.c. signal having a constant waveform, on a sector or sectors corresponding to said directory;
• (e) searching the last position of data prewritten on said disc, such that a sector or sectors whose contents were erased are detected to be skipped;
• (f) writing the renewed data in an unused region which follows said last position;
• (g) renewing the directory stored in said memory so that a new directory designates the position where said renewed data has been written;
• (h) searching the last position of directories which are prewritten in said directory region;
• and
• (i) writing said new directory at an unused region in said directory region which follows said last position of directories.

A method of reading out information prewritten on an optical disc having a file region and a directory region, comprising the steps of:

• (a) detecting a reproduced signal to check an envelope thereof;
• (b) ascertaining whether information in a region can or cannot be read out;
• (c) skipping said region to ascertain whether information in another region can be read out upon determining that information has been erased from the region and that information cannot be read out from said region;
• and
• (d) reading out information from said region upon ascertaining that information in said region can be read out.