JP2903422B2 - Information recording and playback method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for recording and reproducing a signal on a recording medium by a laser, and more particularly, to a method for recording another signal on an information track of a recording medium on which a signal is already recorded. The present invention relates to an information recording and reproducing method for recording and reproducing signals.

(Prior Art) At present, most devices for recording / reproducing information using a laser use a non-erasable recording medium called a write-once such as a phase change or a perforation method. In such a device, the quality of a signal recorded is poor, or old data may be inconvenient to be seen by a user due to updating of the recorded data. In order to cope with such a case, there has been proposed a method which replaces erasing. Japanese Patent Publication No. 63-3379, JP-B-63-3379 discloses an invention that enables a second signal to be superimposedly recorded on an information track on which the first signal has already been recorded. There are inventions such as No. 63-75427. According to the present invention, a part of the unchanged portion between the information pits on the information track left when the high frequency first signal is recorded is changed to the same state as the part whose state has changed by the recording of the first signal. A second signal having a lower frequency component than the first signal is superimposed and recorded so as to be changed.

 FIG. 3 shows a block diagram of a conventional example.

In FIG. 3, reference numeral 1 denotes a laser drive circuit,
Modulates an output (e: first signal) of the first modulation circuit 14 for FM-modulating a signal such as a video signal and a signal having a band lower than that of the first modulation circuit for modulating a signal such as an erasure signal. The output (g: second signal) of the second modulation circuit 15 is selectively input through the switching circuit 16 according to the state. Output switching signal during recording / reproduction (f: recording power ON / OFF control signal)
And ON / OFF signal of laser output. 2
Denotes an optical head, which is a semiconductor laser driven by the laser drive circuit 1, an incident optical system such as a lens and a prism for inputting a laser output to the disk, a signal recorded from reflected light from the disk, Although a recording signal and a servo signal detector for detecting the state of the light on the disk are mounted, the description is omitted because it has no direct relation to the present invention. Numeral 3 denotes a disk on which information tracks 4 schematically shown are recorded in advance at a high density at a track pitch of 1 to 2 .mu.m, and a phase change material, a magneto-optical material, an organic dye material, etc. are applied on the recording surface with high precision. And the optical head 2
Changes in reflectivity due to intensity modulation of laser light from
Information can be recorded in the form of changes in the vertical magnetic field, changes in the absorption spectrum, and the like. In general, track address information, sector information, and the like for knowing the position of the track on the disk are recorded in advance on each track.

The disk 3 is rotated with high precision at a speed determined by the disk motor 7.

Reference numeral 5 denotes a preamplifier for amplifying a recording information signal, a servo signal, and the like read from the disk 3 until the demodulation circuit and the servo circuit at a subsequent stage can sufficiently use the signal.

Reference numeral 6 denotes a first signal reproducing circuit, which in this example demodulates the video signal recorded by FM and outputs the demodulated video signal to an O terminal to an external video device such as a TV.

Reference numeral 8 denotes a focus control circuit which detects a focus state of the laser beam on the disk detected by the optical head 2 and controls the objective lens in a direction perpendicular to the disk to maintain a constant focus state at all times. Circuit.

Reference numeral 9 denotes a tracking control circuit which, like the focus control circuit, detects the position of the laser light on the track of the disk detected by the optical head 2, controls the laser light in the radial direction of the disk, and Due to the eccentricity that the laser beam does not deviate from the desired track,
This is a control circuit for making the track follow the track with high accuracy.

Reference numeral 10 denotes a low-pass filtering circuit (hereinafter abbreviated as LPF), which extracts the second signal component recorded by the modulation circuit 15 so that the command circuit 13 can be read by the comparator 11.

The command circuit 13 also switches the aforementioned recording signal,
In addition to outputting a recording power ON / OFF control signal for the laser drive circuit, a signal for controlling a control circuit such as focus and tracking is also output, but is omitted in the figure.

Also, when the laser light reaches the recording power, the gains of both the focus and tracking control circuits are switched,
Control is also performed so that the gain of the control circuit does not fluctuate due to the laser output.

In the above device, when recording the first signal, the signal e modulated according to the signal I at the input terminal is supplied to the switching circuit.
Preparation for recording input to the laser drive circuit 1 through 16 is completed. After that, the recording power ON / OFF control signal f is recorded according to the timing of the disk rotation phase, etc.
By maintaining the ON state for a necessary period, the optical head 2
The laser mounted on the information track outputs a recording power modulated in intensity by the first signal, and records the first signal on the information track 4 as a change in reflectance.

During playback, the above-mentioned recording power ON / OFF control signal keeps the OFF state, and the above-mentioned laser has a constant output of about 1 mW so that the recording film does not change, and the intensity of reflected light from the disk is modulated by the laser. , The first signal is read, demodulated by the first signal reproducing circuit 6, and output to the O terminal.

Next, when the quality of the recorded first signal is poor, such as when the information of the same track is substantially unreadable, or when information for inhibiting output is recorded as a second signal, the same information track as described above is used. Then, the optical head is accessed, and the switching circuit 16 is switched to the second modulation circuit to complete the preparation for recording the second signal. Then, the recording power ON / OFF control signal f keeps the recording ON state for a necessary period by the timing of the rotation phase of the disk, etc.,
The laser mounted on the optical head 2 uses the second signal to
The intensity-modulated recording power is output, and a second signal is recorded on the information track 4 as a change in reflectance.

At the time of reproduction, the signal is read out in the same manner as the reproduction of the first signal, and the second signal is supplied to the second signal reproduction circuit 12.
, And is supplied to the command circuit 13 to read the above-mentioned prohibition information and the like, and controls the entire device such as stopping the demodulation of the first demodulation circuit.

The first and second recorded by such a device
FIG. 4 schematically shows a part of one track of the signal of FIG.

P3 is a portion called a pit that has undergone an optical change (reflectance, absorption spectrum, magnetic field state) in response to a signal such as video information recorded by the first signal.
Vertical lines are shown for emphasis.

P4 is a portion overwritten by the second signal, and a portion that has undergone the same optical change as the original P3 and a portion that has undergone an optical change due to the overwriting are mixed. This state is shown in the reproduced signal waveform i of FIG. 4, from which the low-frequency component of the P3 portion is extracted and the second signal component is detected.

(Problems to be Solved by the Invention) However, in the above-described configuration, two types of modulation circuits having different bands are required, and a switching circuit thereof is also required, and the configuration of the device is complicated and expensive.

Furthermore, it is not determined whether or not the superimposed signal can be read accurately. As described above, codes such as alternative track information that require accurate information because the already recorded first signal is present as noise. In some cases, it could not be used as information.

SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional drawbacks and use the output of the originally used first modulation circuit to turn on / off the recording state of the laser drive circuit with a signal having a lower frequency than the first signal. An object of the present invention is to provide an information recording / reproducing method in which overwriting is performed a plurality of times in synchronization with the same position of a recorded track, and the overwriting is repeated while confirming until the overwritten second information can be read.

(Means for Solving the Problems) An information recording / reproducing method according to the present invention uses a recording medium which produces an optical change with the intensity of a laser beam to be irradiated, and uses the intensity of the laser beam to change a signal such as an image or a data signal. The recording state is ON / OFF controlled by a second signal having a band lower than that of the first signal on the same information track on the recording medium on which the first signal which has been modulated by the modulation circuit is already recorded, and is generated from the modulation circuit. Irradiating a laser beam for intermittently recording the third signal two or more times a plurality of times on a position on a recording medium in synchronization;
An information recording / reproducing method for superposing and recording a second signal so as to further change an optical change of a portion irradiated with a laser beam, and separating and reproducing the second signal during reproduction.
Is a signal having the same band as the first signal, and after superimposing and recording the second signal, the second signal is passed through a detection circuit for detecting the second signal until the second signal is correctly read. The superposition recording of the signal is repeated a plurality of times while synchronizing the position on the recording medium, and when the second signal is superimposed and recorded, the laser intensity is made higher than at the time of the first signal recording on the same information track. Is the second
The signal information is track management information such as alternative track information indicating track information instead of the same information track, and erasure information indicating that information of the same information track has been erased.

(Function) According to the present invention, the modulation circuit of the device can be realized by one circuit required for the device for modulating an image or a data signal by the above-described method, and the laser drive switching signal is changed by the second signal. By switching the recording / reproducing power and synchronizing the position on the disk to overwrite a plurality of times, the recording pit may overlap the information track of the recording medium on which the first signal is already recorded, The second signal is superimposed and recorded by forming a portion where the recording state is further changed by irradiating the laser beam so that the portion where no pit is formed is also in a recording state, and a portion where the recording state is not changed,
The second signal can be reproduced from the change in the recording state.

Further, by repeatedly overwriting until the superimposed and recorded second signal can be read correctly, the reliability of the second signal can be remarkably improved, and code data such as alternative track information can be recorded. Is what you can do.

(Example) Hereinafter, an information recording / reproducing method of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the relationship between the state of a recording track and a signal in an embodiment of the present invention, using a disk of a type in which the reflectance changes.

FIG. 1a shows an example of the relationship between the irradiation light quantity and the reflectance of a recording medium material whose reflectance changes due to a phase change caused by the irradiation light quantity of a laser such as tellurium oxide. First, a first signal is recorded on an unrecorded information track on the recording medium. For example, a first signal such as a video signal is used as an FM modulation signal,
The first signal is recorded by irradiating the laser with the light amount within the range from A to B in FIG. 1A where the relationship between the irradiation light amount and the reflectance is close to a straight line. The reflectance of the information track after recording is as shown in FIG. 1B, and the first signal is recorded as a change in the reflectance.

The state of the track at this time is shown in the upper part F of each signal waveform corresponding to the signal states b, c, d. In a state where the first signal is recorded, a pattern having a high reflectivity of 1 to 2 μm called a pit corresponding to the signal is generated. At the time of reproducing this signal, the irradiation light quantity is set to C in FIG. 1A which is sufficiently small so that the reflectivity of the recording medium does not change, and the laser is irradiated to detect the change in the reflectivity of the information track.

Here, a state in which the amount of laser light is small enough to cause no change in reflectance as in reproduction is defined as a recording power OFF state, and a state in which the amount of laser is large enough to cause a change in reflectance is defined as a recording power ON state.

Next, FIG. 1c shows a case where the second signal is superimposed and recorded once on the information track on which the first signal is recorded. In this case, the recording power is ON / OFF controlled by the second signal, and the laser light FM-modulated by the first signal is irradiated once. However, the first signal does not necessarily need to be a modulation signal of the input signal input to the signal I input terminal, and may be in a self-excited oscillation state of the modulation circuit. By this irradiation, the information track does not change the reflectance of the portion where the recording power was OFF, and remains at FIG. 1B. However, when the recording power was ON, the irradiation light amount equivalently increased, The reflectivity further changes because the proportion of the recording pits increases.
The state of the pits on the track at this time is, as shown in P1, the pits are partially overwritten on the already recorded first signal in the portion where the second signal indicates the recording power ON. In this state, the reflectivity of the portion where the recording power is ON changes by the same amount as when the intermediate light amount between B and D in FIG. As shown in FIG. 1C, the second signal is superimposed and recorded as the difference in reflectance between the portion where the reflectance does not change and the portion where the reflectance further changes.

Even in this state, if an appropriate filter is selected, the second
Can be read to some extent, but it is difficult to obtain sufficient reliability.

Next, FIG. 1D shows a case where the second signal is superimposed and recorded a plurality of times at the same position on the information track on which the first signal is recorded. In this case, as in the case of c, the second
The recording power is ON / OFF controlled by the signal (1), and a laser beam FM-modulated by the first signal is emitted.

By this irradiation, the reflectivity of the information track in the portion where the recording power was OFF remains unchanged and remains as shown in FIG. 1B, but the irradiation light amount equivalently increases in the portion where the recording power is ON, Since the proportion of the recording pits further increases, the reflectance further changes. At this time, the state of the pit on the track is as shown in P2.
The pit is overwritten many times at the portion where the second signal indicates the recording power ON, and the track of the portion where the second signal indicates the recording power ON is different from the case of c. Has changed to the recorded state for the most part. This is because the reflectance of the portion where the recording power was ON changes by the same amount as when the light amount is D in FIG. 1A, and the reflectance of this information track becomes as shown in FIG. 2
Is superimposed and recorded as a clear difference between the reflectance of the portion where the reflectance does not change and the reflectance of the portion where the reflectance further changes as compared with the case of c.

Here, the plurality of times is the number of times until the second signal can be accurately read, and it is clear that the number of times may be a fixed number of times determined by an experiment. However, as a second feature of the present invention, The second signal is read after being recorded, and learning is performed until the second signal can be read accurately. The number of times is not constant.

It should be noted that the recording power when the second signal is superimposed and recorded is turned on.
As the irradiation light amount in the state is larger than the irradiation light amount at the time of recording the first signal, the amount of change in reflectance becomes larger and the second signal becomes easier to detect during reproduction. Even if the irradiation light amount is equal to or smaller than the irradiation light amount, the same information track can be irradiated many times to equivalently increase the irradiation light amount, change the reflectance, and superimpose and record the second signal.

When reproducing the second signal, a difference between the reflectance of the portion where the reflectance is changed by the superposition recording of the second signal and the reflectance of the portion where the reflectance is not changed is detected. For example, the second signal can be separated and reproduced by inputting a reproduction signal of an information track on which the second signal is superimposed and recorded to a comparator having a comparison reference potential corresponding to the E level in FIG. 1d.

In addition, when the frequency of the second signal is set so as not to overlap with the frequency of the first signal, the frequency filtering circuit that cuts off the first signal and passes the frequency of the second signal has the second signal. The second signal can be separated and reproduced by passing the reproduction signal of the information track on which the signal is superimposed and recorded.

In this example, an example is shown in which the first signal is recorded on the information track by the recording power which is modulated by the incident light amounts A and B in FIG. 1A, but the recording is performed with the laser recording power ON / OFF. Also in this case, the second signal having a lower frequency than the first signal can be superimposed and recorded and reproduced in the same manner as in this example.

Also, according to the present invention, it is apparent that the third signal having a lower frequency than the second signal can be superimposed and recorded on the information track on which the second signal is superimposed and recorded, and reproduced. Therefore, even on a non-erasable recording medium, a signal can be superimposed and recorded on the same information track a certain number of times.

However, there are some restrictions on the number of times of superposition recording. As can be seen from FIG. 1a, as the irradiation light amount is increased, the change in the reflectance of the recording medium decreases, so that the change in the reflectance due to the superimposed recording becomes smaller, and the detection of the superimposed recorded signal becomes more difficult. Become. On the other hand, if the irradiation light amount is too large, the recording medium is destroyed by heat, and it is impossible to superimpose and record the information further.

As described above, the recording modulation signal having substantially the same band as the first signal is recorded on the same track on which the first signal is recorded by the second signal having a lower frequency than the first signal. A highly reliable second signal is obtained by overwriting a signal modulated to be turned on / off plural times in synchronism with the position on the disc and repeating the overwriting until the recorded second signal can be accurately read. Can be recorded.

In this example, the description has been made using the example of the medium in which the reflectance changes. However, as shown by F in FIG. 1, the change rate of the signal is proportional to the space factor of the recording pits on the track. It is apparent that the present invention can be applied to a case where an erasable recording medium is used. Examples of the need for these functions in erasable media include recording of alternative track information and the use of certain types of image information (such as corporate personnel information) when it is difficult to use a specific recording track due to dropout or the like. File, etc.), there is information that can be considered to be not completely erased but to temporarily prohibit the use of the corresponding track and to restore and use it as necessary.

Hereinafter, a block diagram of an embodiment of an apparatus using the present invention will be described with reference to FIG.

FIG. 2 is a block diagram of a disk recording / reproducing apparatus according to the present invention. Portions having the same functions as the blocks of the conventional example described in FIG. 3 are denoted by the same reference numerals, and detailed description will be omitted.

In FIG. 2, e is a first signal, f is a laser recording power ON / OFF control signal (hereinafter abbreviated as recording power ON / OFF control signal), 1 is a laser drive circuit, 2 is an optical head, and 3 is an optical head. Reference numeral 4 denotes an information track on the disk 3, 5 denotes a preamplifier, 6 denotes a first signal reproducing circuit, 7 denotes a disk motor, 8 denotes a focus control circuit, and 9 denotes a tracking control circuit. Reference numeral 10 denotes an LPF, reference numeral 11 denotes a comparator, and reference numeral 12 denotes a second signal reproducing circuit, which includes the LPF 10 and the comparator 11. Reference numeral 13 denotes a command circuit, reference numeral 14 denotes a modulation circuit, and reference numeral 17 denotes a mark detector that detects a synchronization mark recorded at a specific position on the disk as necessary.

It is to be noted that the disk 3 of the present embodiment is of a type having a characteristic of causing a change in reflectance depending on the intensity of a laser beam to be irradiated, as described in FIG.

First, the first unrecorded information track 4 on the disc 3
When recording the signal e, the recording power ON / OFF control signal f holds the recording power ON state while recording the first signal e on the information track 4 and outputs the first signal which is the output of the modulation circuit 14. e is converted by the laser drive circuit 1 and the optical head 2 into the intensity of the irradiation light, and is recorded on the information track 4 on the disk 3 being rotated by the disk motor 7.

When reproducing the first signal e, the recording power ON / OFF control signal f is set to 1 by maintaining the recording power OFF state.
The output of the laser is controlled to about mW,
A signal corresponding to a change in reflectance is taken out from the upper information track 4 and passed through a preamplifier 5 to a first signal reproducing circuit 6.
To reproduce the first signal. Focus control circuit
8, The tracking control circuit 9 is switched to a gain corresponding to the recording power ON state and the gain power OFF state in accordance with the switching timing of the recording power ON / OFF control signal f, and performs optimum focus and tracking control respectively.

Next, a method for superimposing and recording a second signal having a lower frequency than the first signal on the information track 4 on which the first signal e is recorded by the above method will be described. When recording the second signal, the recording power ON / OFF control signal f is replaced with the second signal. It does not matter if there is no input signal to be modulated by the modulation circuit 14. In that case, the output of the modulation circuit 14 oscillates at a constant self-excitation wave number.

The laser drive circuit 1 turns on the recording power by the second signal.
The laser drive corresponding to / OFF is performed, and the optical head 2 irradiates the information track 4 on the disk 3 with the laser light a plurality of times while synchronizing the position on the disk.

In order to synchronize the position of the second signal to be recorded on the disc, the command circuit 13 uses the output of the mark detector 17 to read the synchronization mark 3m previously recorded at a specific position on the disc as necessary. Thus, the second signal can be generated. It is also possible to use the detection timing of an address signal which is recorded in advance on each track of the disk and indicates the position of each track.

The number of times of recording a plurality of times may be a fixed number of times confirmed by an experiment. However, the output of the reproduction circuit 12 of the above-mentioned second signal is recorded and reproduced by the command circuit 13 until it can be accurately read. It is preferable to repeat. The repetition period of the recording and reproduction confirmation may be made to correspond to one recording, such as one reproduction confirmation, or may be one recording.
It is not necessarily one such as one playback confirmation for three or more times
It is not necessary to correspond to one-to-one. Also, due to special circumstances such as drop-out of the disc, even if the number of repetitions is increased without limit, accurate recording of the second signal may not be realized. It is also effective to set the upper limit number of times within a range that does not cause trouble such as destruction.

As a result of the recording of the above-mentioned second signal, as shown in FIG. 1d, the portion where the reflectance further changed due to the irradiation light amount in the recording power ON state and the reflection due to the irradiation light amount in the recording power OFF state. A portion where the rate remains the state where the first signal e is recorded is formed, and the second signal is superimposed and recorded. At this time, the focus control circuit 8 and the tracking control circuit 9 change the recording power ON state and the recording power OF in accordance with the switching timing of the recording power ON / OFF control signal f (second signal).
Performs optimal focus and tracking control for each F state.

When reproducing the second signal, the recording power ON / OFF control signal f maintains the recording power OFF state, and the optical head 2 extracts a signal corresponding to the change in the reflectance from the information track 4 on the disk 3, The signal passes through the preamplifier 5 and
Is input to the LPF 10 in the reproduction circuit 12. LPF10 is
It has a frequency characteristic of blocking the first signal and passing the second signal, and extracts a change in reflectance caused by superimposing and recording the second signal by the LPF 10,
By shaping the waveform according to 11, the second signal can be reproduced.

This second signal is constituted by a specific modulation pattern included in the device, and is a signal for inhibiting the use of the corresponding track, or alternative track information indicating an alternative track, or is controlled so as not to output and apparently erased. The information is deciphered by the command count 13 as information meaning an erasure signal for making the first signal demodulation circuit stop, access to an alternate track,
It is used by outputting management information such as the above prohibition and substitution to an external device.

As described above, the recording modulation signal having substantially the same band as the first signal is recorded on the same track on which the first signal is recorded by the second signal having a lower frequency than the first signal. The signal modulated to be turned on / off is overwritten multiple times in synchronism with the position on the disc, and the overwriting is repeated until the recorded second signal can be read accurately. It is possible to record a second signal having a high level. This makes it possible to use code information indicating an alternative track, which is difficult to obtain by the conventional method.

Although the present embodiment has been described using a write-once device in which the reflectivity changes, as described in FIG. 1, the recording method of the present invention uses a material such as magneto-optical or erasable phase change. It is also possible to adapt to the erasable device used.

Further, the present invention is applicable to an apparatus such as an optical card other than the disc-shaped recording medium, and can be used as use prohibition information of a specific information track, alternative track information, and erase information.

(Effects of the Invention) According to the present invention, a recording modulation signal having substantially the same band as the first signal is recorded on the same track on which the first signal is recorded by the second signal having a lower frequency than the first signal. By overwriting a signal modulated so that the recording state is turned ON / OFF by a signal, synchronizing the position on the disk multiple times, and repeating the overwriting until the recorded second signal can be accurately read. In addition, a highly reliable second signal can be recorded with a simple configuration that does not require an additional modulation circuit or switching circuit. As a result, code information indicating an alternative track, which is difficult to obtain by the conventional method, can be used with a simple configuration.

Further, by superimposing and recording the second signal on the same information track as information indicating erasure of the information of the first signal or information indicating the position of an information track instead of the information of the first signal, the information is superimposed. Enable / disable track information,
Alternatively, the management of information tracks on a recording medium can be realized without providing a special information track for managing the position of the information track instead of the information track, and the practical effect is extremely large.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a change in reflectance of a recording medium according to the present invention, FIG. 2 is a block diagram of a disk recording / reproducing apparatus according to the present invention, FIG. 3 is a block diagram of a conventional recording / reproducing apparatus, FIG. FIG. 4 is a schematic diagram showing a conventional disk change state. REFERENCE SIGNS LIST 1 laser drive circuit 2 optical head 3 disk 4
... information track, 5 ... preamplifier, 6 ... first signal reproduction circuit, 7 ... disk motor, 8 ... focus control circuit, 9 ... tracking control circuit, 10 ... low-pass filter circuit (LP)
F), 11 ... comparator, 12 ... reproduction circuit of second signal, 1
3 ... Command circuit, 14 ... Modulation circuit, 17 ... Mark detector, e ...
A first signal, f: a laser recording power ON / OFF control signal,
P, P1, P2 ... Recording pit.

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/00 G11B 20/18

Claims (4)

(57) [Claims] 1. A recording medium in which an optical change is caused by the intensity of a laser beam to be irradiated, and a first signal obtained by modulating a signal such as a video signal or a data signal by a modulation circuit according to the intensity of the laser beam is already recorded. On / off control of the recording state is performed on the same information track on the recording medium by a second signal having a band lower than that of the first signal, and a third signal generated from the modulation circuit is generated.
The laser light for recording the signal intermittently two or more times, irradiating the position on the recording medium in synchronization, further changing the optical change of the portion irradiated with the laser light, The second signal is superimposed and recorded, and the second signal is reproduced.
An information recording / reproducing method for separating and reproducing the signal of (1), wherein the third signal is a signal having the same band as the first signal. 2. After the second signal is superimposed and recorded, the superimposed recording of the second signal is recorded on a recording medium until the second signal is correctly read through a detection circuit for detecting the second signal. 3. The information recording / reproducing method according to claim 1, wherein the position is repeated a plurality of times in synchronization. 3. The method according to claim 1, wherein when the second signal is superimposed and recorded, the laser intensity is made higher than when recording the first signal on the same information track.
Information recording and reproduction method described. 4. The information of the second signal is track management information such as alternative track information indicating track information instead of the same information track, and erasure information indicating that the information of the same information track has been erased. The information recording / reproducing method according to claim 1 or 2, wherein: