Information recording medium disc and method and apparatus for recording/reproducing information

Claim 2

An information recording medium disc comprising a recording layer on which information can be recorded repeatedly with pre-recorded information being erased, said recording layer having a spiral guide track formed in the form of geometrical variations so as to carry at least a synchronous signal and cumulative time data indicative of the lapse of time during either recording or reproducing from a predetermined point on said recording layer, said spiral guide track functioning as a ROM track being formed such that a portion between adjacent spiral guide tracks is a flat land area which is used as a spiral RAM track for recording/reproducing information.

Claim 3

An information recording disc as claimed in Claim 1, wherein said synchronous signal and cumulative time data are both provided at a predetermined space along said ROM track.

Claim 4

An information recording disc as claimed in Claim 2, wherein said synchronous signal and cumulative time data constitute a pilot signal block with an elongate groove so that said ROM track includes a number of continuous pilot signal blocks each having an identical length.

Claim 5

An information recording disc as claimed in Claim 3, wherein said synchronous signal comprises a synchronous bit portion including a plurality of bits represeing synchronous code, and a rotation synchronous signal including an impulse of a predetermined width.

Claim 6

An information recording disc as claimed in Claim 1, wherein said recording layer comprises a lead-in signal area, a main signal recording area, and a lead-out signal area, said cumulative time data being included in said lead-in signal area and said main signal recording area, said lead-out signal area including a lead-out signal indicating of an end of said recording layer, said main signal recording area being interposed between said lead-in signal are and said lead-out signal area.

Claim 7

An information recording disc as claimed in Claim 5, wherein said cumulative time data located at a boundary between said lead-in signal area and said main signal recording area is arranged to represent zero so that said cumulative time data located in said main signal recording area is arranged to represent positive time values increasing to a predetemined time value and said cumulative time data located in said lead-in signal areas is arranged to repreent negative time values decreasing to a predetermined time value.

Claim 8

An information recording disc as claimed in Claim 5, wherein said lead-in signal area is located at an inner portion of said disc wheile said lead-out signal area is located at an outer portion of said disc.

Claim 9

An information recording disc as claimed in Claim 5, wherein said lead-out signal area is located at an inner portion of said disc wheile said lead-in signal area is located at an outer portion of said disc.

Claim 10

An information recording disc as claimed in Claim 1, wherein the width of said spiral groove is less than or equal to 40 percent of groove pitch of said spiral groove.

Claim 13

ll. A method of recording information as claimed in Claim 10, further comprising the step of: recording only lead-out signal in said RAM track in said lead-out signal area when said lead-out signal is read out from said ROM track adjacent to said RAM track.

Claim 14

A method of recording information as claimed in Claim 10, further comprising the steps of: (a) recording cumulative time data read out from said ROM track adjacent to said RAM track, on said RAM track over several revolutions of said disc when recording of said main signal is interrupted; (b) subsequently recording lead-out signal in said RAM track which lead-out signal has been read out from said ROM track adjacent to said RAM track; (c) shifting said record head so that a light beam therefrom is directed to said lead-in signal area; and (d) recording lead-in information, in said RAM track in said lead-in signal area, corresponding to said chapter number and said cumulative time data of said piece of information just recorded in said RAM track in said main signal recording area.

Claim 15

A method of recording information as claimed in Claim 12, further comprising the steps of: (a) putting said record head in stand by state, when a further piece of main information is to be recorded, so that light beam therefrom is located at a portion where said cumulative time data is pre-recorded on said RAM track over several revolutions of said disc; and (b) recording said further piece of main information by said record head on said RAM track in said main signal recording area together with a chapter number assigned to a piece of information to be recorded and with cumulative time data read out from said ROM track adjacent to said RAM track so that said further piece of main information is recorded at a place following a newest piece of main information recorded while said cumulative time data of recorded together with said further piece of main information represents time which continues from time represented by cumulative time data recorded together with the newest piece of main information.

Claim 16

A method of recording information as claimed in Claim 13, further comprising the steps of: (a) recording cumulative time data read out from said ROM track adjacent to said RAM track, on said RAM track over several revolutions of said disc when recording of said main signal is interrupted; (b) subsequently recording lead-out signal in said RAM track which lead-out signal has been read out from said ROM track adjacent to said RAM track; (c) shifting said record head so that a light beam therefrom is directed to said lead-in signal area; and (d) recording lead-in information, in said RAM track in said lead-in signal area, corresponding to said chapter number and said cumulative time data of said piece of information just recorded in said RAM track in said main signal recording area.

Claim 17

A method of recording information as claimed in Claim 10, further comprising a step of: performing tracking control by tracing two of said ROM tracks at both sides of said RAM track on which said main information is to be recorded or pre-recorded main information is to be reproduced therefrom, said tracking control being performed using two laser light spots while recording/reproducing of said main information on and from said RAM track being performed using one laser light spot arranged at the middle of said two laser light spots, said three laser light spots being arranged in line in a direction having a given angle with respect to said RAM track so that one of said two laser light spots which spot precedes said laser light spot used for recording/reproducing said main information relative to disc movement is used for reading out said synchronous signal and said cumulative time data.

Claim 18

A method of recording information as claimed in Claim 15, further comprising a step of: (a) reproducing pre-recorded main information from said main track; and (b) reducing the intensity of three laser light beams producing said three laser light spots when said reproducing said pre-recorded main information so that the intensity is lower than that used for recording main information.

Claim 19

Apparatus for recording/reproducing information on an information recording disc having a recording layer in which information can be recorded repeatedly with pre-recorded information being erased, said recording layer having a spiral guide track formed in the form of geometrical variations so as to carry at least a synchronous signal and cumulative time data indicative of the lapse of time during either recording or reproducing from a predetermined point on said recording layer, said spiral guide track functioning as a ROM track being formed such that a portion between adjacent spiral guide tracks is a flat land area which is used as a spiral RAM track for recording/reproducing information, said recording layer having a lead-in signal area, a main signal recording'area, and a lead-out signal area, said cumulative time data being included in said ROM track in said lead-in signal area and said main signal recording area, said lead-out signal area including a lead-out signal indicating an end of said recording layer, said main signal recording area being interposed between said lead-in signal area and said lead-out signal area, said apparatus comprising: (a) disc drive means for rotating said information recording disc at a constant linear velocity usinc a synchronous signal; (b) record/reproduce head means for applying laser light beams to said disc so that three laser light spots are directed to said recording layer of said disc for writing and reading main information on and from said RAM track using one of said three laser light spots and for reading, during writing and reading of said main information, information from two adjacent ROM tracks on both sides of said RAM track used for writing or reading using remaining two laser light spots, said record/reproduce head having a plurality of photosensitive elements responsive to light rays reflectecd at said recording layer of said disc at said three laser light spots, at least two of said photosensitive elements which are responsive to reflected light rays from said remaining two laser light spots producing tracking signals by reading the same from said two ROM tracks, while one of said two photosensitive elements producing synchronous signal and cumulative data by reading the same from one of said two said ROM tracks; (c) shifting means for shifting said record/reproduce head to place said three laser light spots at desired positions; (d) tracking control circuit responsive to said tracking signals from said record/reroduce head means for performing tracking control; (e) record/reproduce circuit means for processing a recording signal to be applied to said record/reproduce head and a reproduced signal from said record/reproduce head; and (f) control means for controlling said motor dirve means, said record/reproduce head, said shifting means, said tracking control circuit, said record/reproduce circuit means so as to record and/or reproduce information on and from said disc at desired positions, said control means having a memory for storing chapter number and cumulative time data both read out from said RAM track in said lead-in signal area for controlling said shifting means when such number and data are pre-recorded.

Claim 20

Apparatus for recording/reproducing information on an information recording disc having a recording layer in which information can be recorded repeatedly with pre-recorded information being erased, said recording layer having a spiral guide track formed in the form of geometrical variations so as to carry at least a synchronous signal and cumulative time data indicative of the lapse of time during either recording or reproducing from a predetermined point on said recording layer, said spiral guide track functioning as a ROM track being formed such that a portion between adjacent spiral guide tracks is a flat land area which is used as a spiral RAM track for recording/reproducing information, said recording layer having a lead-in signal area, a main signal recording'area, and a lead-out signal area, said cumulative time data being included in said ROM track in said lead-in signal area and said main signal recording area, said lead-out signal area including a lead-out signal indicating an end of said recording layer, said main signal recording area being interposed between said lead-in signal area and said lead-out signal area, said apparatus comprising: (a) disc drive means for rotating said information recording disc at a constant linear velocity usinc a synchronous signal; (b) record/reproduce head means for applying laser light beams to said disc so that three laser light spots are directed to said recording layer of said disc for writing and reading main information on and from said RAM track using one of said three laser light spots and for reading, during writing and reading of said main information, information from two adjacent ROM tracks on both sides of said RAM track used for writing or reading using remaining two laser light spots, said record/reproduce head having a plurality of photosensitive elements responsive to light rays reflectecd at said recording layer of said disc at said three laser light spots, at least two of said photosensitive elements which are responsive to reflected light rays from said remaining two laser light spots producing tracking signals by reading the same from said two ROM tracks, while one of said two photosensitive elements producing synchronous signal and cumulative data by reading the same from one of said two said ROM tracks; (c) shifting means for shifting said record/reproduce head to place said three laser light spots at desired positions; (d) tracking control circuit responsive to said tracking signals from said record/reroduce head means for performing tracking control; (e) record/reproduce circuit means for processing a recording signal to be applied to said record/reproduce head and a reproduced signal from said record/reproduce head; and (f) control means for controlling said motor dirve means, said record/reproduce head, said shifting means, said tracking control circuit, said record/reproduce circuit means so as to record and/or reproduce information on and from said disc at desired positions, said control means having a memory for storing chapter number and cumulative time data both read out from said RAM track in said lead-in signal area for controlling said shifting means when such number and data are pre-recorded.

Claim 21

Apparatus for recording/reproducing information as claimed in Claim 17, further comprising a focus control means reponsive to an output signal from at least one of said photosensitive elements of said record/reproduce head.

Claim 22

Apparatus for recording/reproducing information as claimed in Claim 17, further comprising a data input means for manually inputting data including a chapter number to be assigned to a piece of information to be recorded a chapter number for designating a pre-recorded piece of information.