Optical recording medium, reproducing system, method of reproducing optical disk, method of fabricating optical disk original record, and method of stopping illegal program operation

An optical recording medium having a first recording area where an offset signal in which a duty ration of a signal recording section in a recording track is shifted from a standard value is recorded and a second recording area where a signal indicative of the fact that said first recording area is provided and/or the position whereat said first recording area is recorded.

A method of fabricating an optical disk original record for forming and manufacturing an optical disk having a first recording area where an offset signal in which a duty ration of a signal recording section in a recording track is shifted from a standard value is recorded and a second recording area where a signal indicative of the fact that said first recording area is provided and/or the position whereat said first recording area is recorded, comprising the steps of applying a photoresist on a base material for said optical disk original record, making said photoresist exposed to light intensity-modulated in accordance with an information signal to be recorded, and developing said photoresist to form an irregular pit configuration corresponding to its sensitivity on said base material for said optical disk original record, wherein for the formation of said irregular pit configuration a recording equalizing quantity for said information signal is changed so that a duty ration of a length of each of pits to a distance between said pits is changed to form a signal area where a center of an eye pattern is shifted from a center of an amplitude in a specific relationship.

A method of fabricating an optical disk original record for forming and manufacturing an optical disk having a first recording area where an offset signal in which a duty ration of a signal recording section in a recording track is shifted from a standard value is recorded and a second recording area where a signal indicative of the fact that said first recording area is provided and/or the position whereat said first recording area is recorded, comprising the steps of applying a photoresist on a base material for said optical disk original record, making said photoresist exposed to light intensity-modulated in accordance with an information signal to be recorded, and developing said photoresist to form an irregular pit configuration corresponding to its sensitivity on said base material for said optical disk original record, wherein for the formation of said irregular pit configuration the intensity of said light to which said photoresist is exposed is changed to form a signal area where a center of an eye pattern is shifted from a center of an amplitude in accordance with the change of the light intensity.

A method of fabricating an optical disk original record for forming and manufacturing an optical disk having a first recording area where an offset signal in which a duty ration of a signal recording section in a recording track is shifted from a standard value is recorded and a second recording area where a signal indicative of the fact that said first recording area is provided and/or the position whereat said first recording area is recorded, comprising the steps of applying a photoresist on a base material for said optical disk original record, making said photoresist exposed to light intensity-modulated in accordance with an information signal to be recorded, and developing said photoresist to form an irregular pit configuration corresponding to its sensitivity on aid base material for said optical disk original record, wherein for the formation of said irregular pit configuration a recording equalizing quantity for said information signal is increased and the intensity of said light to which said photoresist is exposed is lowered, or said recording equalizing quantity for said information signal is decreased and the intensity of said light to which said photoresist is exposed is increased, thereby forming a signal are in which a center of an eye pattern is shifted from a center of an amplitude.

A method of reproducing an optical disk comprising a step of, after a signal having a specific pattern is detected, changing a threshold value to be used in demodulating an RF signal into a digital signal.

A reproducing system for an optical disk comprising means for, after a signal having a specific pattern is detected, changing a threshold value to be used in demodulating an RF signal into a digital signal.

An optical disk reproducing system which reads out, through an optical head, a data signal including a program modulated and recorded on an optical disk to reproduce an analog signal, and slices through a slice circuit, said analog signal with a slice voltage corrected with an offset voltage being applied to a reference slice voltage in accordance with a duty ratio of said analog signal to reproduce a first digital signal, and demodulates said first digital signal into a second digital signal through a demodulator to reproduce a third digital signal from said second digital signal through an error correction circuit, said reproducing system comprising an offset signal variation detecting section for detecting that said offset voltage varies in a specific state, and means for, when said offset signal variation detecting section does not detect that said offset signal is in said specific state, stopping one of an output of said data and an operation of said program.

An illegal program operation stopping method using a reproducing system which reads out, through an optical head, a data signal including a program modulated and recorded on an optical disk to reproduce an analog signal, and slices through a slice circuit, said analog signal with a slice voltage corrected with an offset voltage being applied to a reference slice voltage in accordance with a duty ratio of said analog signal to reproduce a first digital signal, and demodulates said first digital signal into a second digital signal through a demodulator to produce a third digital signal from said second digital signal through an error correction circuit, wherein an offset signal variation detecting section is provided in said reproducing system to detect that said offset voltage varies in a specific state, and when said offset signal variation detecting section does not detect that said offset signal is in said specific state, one of an output of said data and an operation of said program is stopped.