Optical disc, device for checking optical disc and device for recording information on optical disc

Claim 2

An optical disc as claimed in claim 1, wherein the said signal is a tracking error signal.

Claim 3

An optical disc as claimed in claim 1 or claim 2, wherein the signal is an RF signal and the symmetry of a waveform of the RF signal varies due to the train of the irregular pits.

Claim 4

An optical disc as claimed in claim 1 or claim 2, wherein the signal is a light signal and the light amount signal varies due to the train of the irregular pits.

Claim 5

An optical disc comprising: a predetermined number of spiral trains of regular pits; and at least one train of irregular pits, the regular pits of each of the trains being arranged symmetrically with respect to the track centre, each of the irregular pits having a predetermined shape different from a shape of each of the regular pits, the irregular pits being arranged intermittently on a predetermined area corresponding to data blocks represented by a modulation signal recorded as the trains of the regular pits.

Claim 6

The optical disc according to any of claims 1 to 5, wherein each of the irregular pits of the train is arranged on a centre line wobbled in a radial direction by a maximum amplitude smaller than a track pitch.

Claim 7

The optical disc according to claim 6, wherein a wobbling frequency is higher than any frequency of a tracking servo band and is a frequency at which a reproduced signal component included in a tracking error signal becomes minimum and conversely, a wobbling signal carrier becomes maximum when a signal is reproduced by an optical pickup using a side beam for tracking.

Claim 8

The optical disc according to any preceding claim, wherein the train of the irregular pits are arranged on a portion of the disc, where a reproduced signal component included in the said signal becomes small.

Claim 9

The optical disc according to any preceding claim, wherein a duty factor of each of the irregular pits is not equal to that of each of the regular pits.

Claim 10

The optical disc according to any preceding claim, wherein a width in a radial direction of each of the irregular pits is not equal to that in the radial direction of each of the normal pits.

Claim 11

A checking device for checking an optical disc according to any preceding claim, the checking device comprising: reproducing means for reading an area on which the train of the irregular pits is arranged; and judgement means for detecting from the result of a reading whether or not a train of irregular pits is present, and for judging from the result of a detection whether a checked optical disc is a normal disc or an illegal copy disc.

Claim 12

The checking device according to claim 11, wherein the reproducing means has a decoding unit for reading a data block from an information recording portion of the optical disc and decoding the data block, wherein the judgement means comprises: a first detection unit for detecting whether a servo signal or a data signal is normal or abnormal; a second detection unit for detecting whether or not output signals of the decoding unit and the first detecting unit are related to each other at a predetermined regular point of time; and a judgement unit for judging from a detection signal outputted from the second detection signal whether or not an irregular pit preliminarily recorded on the disc is detected, wherein it can be determined for each volume of the optical disc to be checked whether the optical disc has only regular pits or whether the optical disc has had an irregular pit preliminarily recorded thereon.

Claim 13

The checking device according to claim 12, which further comprises a tracking error signal detection unit for detecting a tracking error signal; a third detection unit for detecting whether the signal level of the tracking error signal is nearly constant or changes like that of a burst signal; and a control unit for judging from the tracking error signal whether or not an irregular pit is detected in the read optical disc and for controlling a reading operation to be effected after the judgement is made, whereby each volume of the optical disc can be discriminated on the basis of the presence or absence of an irregular pit.

Claim 14

The checking device according to claim 13, wherein the tracking error signal detection unit employs a three-spot tracking method, and the third detection unit comprises a bandpass filter circuit, a rectifying circuit and a comparator circuit, and the centre frequency of the bandpass filter circuit is set to be a frequency at which the level of a burst signal appearing in the tracking error signal becomes maximum and the leakage of a data signal appearing in the tracking error signal becomes minimum.

Claim 15

The checking device according to claim 11 or claim 12, wherein the judgement means comprises a third detection unit for detecting the symmetry of a waveform of an RF signal with respect to a slicing level of the RF signal, a slicing-level changing unit for changing the slicing level of the RF signal according to the detected symmetry, a comparison unit for determining whether or not the change in slicing level is within a reference range and a judgement unit for judging from an output signal of the comparison unit whether or not an irregular pit is detected in the read optical disc, whereby each volume of the optical disc can be discriminated on the basis of the presence or absence of an irregular pit.

Claim 16

The checking device according to claim 11 or claim 12, wherein the judgement means comprises an amount-of-reflected-light signal generating unit for irradiating an information recording portion of the optical disc with laser light and outputting an amount-of-reflected-light signal representing an amount of light reflected by the optical disc, a comparison unit for determining whether or not change in the amount-of-reflected-light signal is within a reference range, an expansion unit for expanding an output signal of the comparison unit and a judgement unit for judging from an output signal of the expansion unit whether or not an irregular pit is detected in the read optical disc, whereby each volume of the optical disc can be discriminated on the basis of the presence or absence of an irregular pit.

Claim 17

The checking device according to claim 11 or claim 12, wherein the judgement means comprises a third detection unit for reading data recorded at each of predetermined addresses in data block recorded on the optical disc and judging whether or not an irregular pit is detected in the disc, by determining whether or not a tracking error signal changing like a burst signal is detected in synchronisation with a regular point of time determined according to data recorded at the read address, or determining whether or not variation in slicing level corresponding to symmetry of a waveform of the RF signal with respect to a slicing level thereof is detected in synchronisation with a regular point of time, or determining whether or not variation in amount of light reflected by the disc is detected in synchronisation with the regular point of time, whereby each volume of the optical disc can be discriminated on the basis of the presence or absence of an irregular pit.

Claim 18

The checking device according to claim 11 or claim 12, wherein the judgement means comprises a third detection unit for reading data recorded at each of predetermined addresses in data block recorded on the optical disc and judging that an irregular pit is detected in the disc, if it is judged more than a predetermined number of times that a tracking error signal changing like a burst signal is detected in synchronisation with a regular point of time determined according to data recorded at the read address, or that variation in slicing level corresponding to the symmetry of the waveform of the RF signal with respect to the slicing level thereof is detected in synchronisation with the regular point of time, or that variation in amount of light reflected by the disc is detected in synchronisation with the regular point of time, and if it is judged more than a predetermined number of times that a tracking error signal changing like a burst signal is not detected in synchronisation with a regular point of time determined according to data recorded at the read address, or that variation in slicing level corresponding to the symmetry of the waveform of the RF signal with respect to the slicing level thereof is not detected in synchronisation with the regular point of time, or that variation in amount of light reflected by the disc is not detected in synchronisation with the regular point of time.

Claim 19

The checking device according to claim 11 or claim 12, wherein the judgement means comprises a storage unit for storing a predetermined address of data block stored in the optical disc, which block is used for determining a kind of the optical disc from a result of judging whether or not an irregular pit is detected among information pits formed on the disc, and a third detection unit for reading the data block recorded at the predetermined address when setting the optical disc and for judging whether or not an irregular pit is detected in the disc, by determining whether or not a tracking error signal changing like a burst signal is detected in the data block, or determining whether or not variation in slicing level of the RF signal is detected in the data block, or determining whether or not variation in the level or an amount-of-reflected-light signal is detected in the data block, whereby each volume of the optical disc can be discriminated on the basis of the presence or absence of an irregular pit.

Claim 20

The checking device according to claim 11 or claim 12, wherein the judgement means comprises a storage unit for storing a predetermined address, at which a table of addresses of data block is stored in the optical disc, the data block being used for determining a kind of the optical disc from the result of judging whether or not an irregular pit is detected among information pits formed on the disc, and a third detection unit for reading the table at the predetermined address, and next reading the data block stored at the address listed in the table when setting the optical disc and for judging whether or not an irregular pit is detected in the disc, by determining whether or not a tracking error signal changing like a burst signal is detected in the data block, or determining whether or not variation in slicing level of the RF signal is detected in the data block, or determining whether or not variation in level of an amount-of-reflected-light signal is detected in the data block, whereby each volume of the optical disc can be discriminated on the basis of the presence or absence of an irregular pit.

Claim 21

A recording device for recording data on an optical disc having a number of spiral trains of regular pits and at least one train of irregular pits, the regular pits of each of the trains being arranged symmetrically with respect to the track centre, each of the irregular pits having a predetermined shape different from a shape of each of the regular pits, the irregular pits being arranged intermittently on a predetermined area correspondingly to data blocks represented by a modulation signal recorded as the trains of the regular pits, the recording device comprising: laser light source means for generating and outputting laser light; signal conversion means for converting digital data into a modulation signal; laser-light modulation means for performing an intensity modulation on laser light outputted from the laser light source means according to the modulation signal; gate signal generating means for generating a gate signal in synchronisation with each data block represented by the modulation signal; laser light changing means for changing laser light correspondingly to the train of the irregular pits in synchronisation with the gate signal; and laser light irradiating means for irradiating laser light, which is modulated and changed by the laser light modulation means and the laser light changing means, respectively, onto the optical disc to form a train of pits.

Claim 22

An information recording device comprising: a laser light source; conversion means for converting digital data into a modulation signal; modulation means for performing an intensity modulation on laser light emitted from the laser light source according to the modulation signal to thereby convert the laser light into recording laser light; an objective lens for irradiating an optical disc with the recording laser light and for forming trains of pits on the optical disc; gate signal generating means for generating a gate signal in synchronisation with each data block represented by the modulation signal; and irregular-pits generating means for generating a train of irregular pits in synchronisation with the gate signal.

Claim 23

An information recording device comprising: a laser light source; conversion means for converting digital data into a modulation signal; modulation means for performing an intensity modulation on laser light emitted from the laser light source according to the modulation signal to thereby convert the laser light into recording laser light; an objective lens for irradiating an optical disc with the recording laser light and for forming trains of pits on the optical disc; gate signal generating means for generating a gate signal in synchronisation with each data block represented by the modulation signal; wobbling-signal generating means for generating a wobbling signal in synchronisation with the gate signal; and shifting means for shifting a laser spot of the recording laser light, which spot is formed on the optical disc, in the radial direction thereof according to the wobbling signal.

Claim 24

An information recording device comprising: a laser light source; conversion means for converting digital data into a modulation signal; modulation means for performing an intensity modulation on laser light emitted from the laser light source according to the modulation signal to thereby convert the laser light into recording laser light; an objective lens for irradiating an optical disc with the recording laser light and for forming trains of pits on the optical disc; gate signal generating means for generating a gate signal in synchronisation with each data block represented by the modulation signal; and duty-factor changing means for changing the duty factor of the modulation signal according to the gate signal.

Claim 25

An information recording device comprising: a laser light source; conversion means for converting digital data into a modulation signal; modulation means for performing an intensity modulation on laser light emitted from the laser light source according to the modulation signal to thereby convert the laser light into recording laser light; an objective lens for irradiating an optical disc with the recording laser light and for forming trains of pits on the optical disc; gate signal generating means for generating a gate signal in synchronisation with each data block represented by the modulation signal; and width changing means for changing the width in the radial direction of the train of the pits according to the gate signal.

Claim 26

A recording device according to any of claims 21 to 24 for use in producing an optical disc as claimed in any of claims 1 to 10.