JP3306934B2 - Optical recording medium and address detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium for optically recording or reproducing information, and more particularly to an increase in its storage capacity.

[0002]

2. Description of the Related Art In recent years, since a great deal of information can be recorded on an optical recording medium, its use value is increasing more and more.

Hereinafter, a conventional optical recording medium will be described with reference to the drawings. FIG. 7 is a schematic plan view of a conventional optical recording medium. A servo area 71 is formed along a track center line 70 (actually, a spiral or concentric circle with respect to a disk-shaped recording medium) indicated by a dashed line. Data area 72
Are provided alternately and periodically. In the servo area 71, a clock mark 73 for generating a synchronous clock is provided on the track center line 70. When the optical recording medium is rotated at a constant angular velocity, the clock mark 73 is the same on any track. It is arranged to be played at time intervals. Wobble marks 74a and 74b for obtaining a tracking error signal are provided before and after the clock mark 73, and the wobble mark 74a is located above the center line 70 in FIG.
4b is displaced downward. Behind the servo area 71 in the operation direction, address marks (also referred to as gray codes) 75a and 75b, which are digital codes indicating a track address (address) during track search, are provided. In the data area 72, an information sequence can be recorded at intervals synchronized with a synchronization clock created based on the clock mark 73.

Next, an example of the operation of the system when information is recorded or reproduced on such an optical recording medium will be described. A light source such as a laser is focused, and an optical head that generates this light beam scans around the track center line 70 to read a clock mark 73. In detecting the clock mark 73, for example, the clock mark 73 is detected by checking the interval between the wobble marks 74a and 74b. Since the clock mark 73 is always reproduced at the same time interval as described above, a synchronous clock is generated on the circuit side based on this. Then, the wobble marks 74a and 74b are sampled on the basis of the synchronization clock to perform tracking control. Then, information is recorded or reproduced in the data area 72 in synchronization with the synchronous clock created as described above.

Further, when executing a track search,
The address marks 75a and 75b are sampled by the synchronous clock, and the optical head knows the address of the current track. Then, the tracking control of the optical head is released, and the optical head is moved in a direction perpendicular to the track. During this time, the address mark is continuously read, and when the track address matches the track address to be searched, the movement of the optical head is stopped, and the tracking control is performed again.

[0006]

In the above-mentioned conventional optical recording medium, when the density of recorded information is to be increased, the track pitch (interval) must be reduced. However, since the luminous flux has a certain spread, when information is recorded on a certain track, there is a possibility that already recorded information on an adjacent track may be damaged. In order to avoid this, a track groove (groove-shaped one) is required. That is, if information is recorded in the groove, there is no effect on the adjacent groove.

By the way, it is better not to record marks near the start and end of the track groove. The reason is that it is difficult to distinguish between the recorded information mark and the groove edge signal at the time of signal reproduction (details will be described with reference to the drawing (FIG. 3) in the embodiment). Must be put in the servo area, and then the servo area must be widened. Therefore, there is a problem that the data area becomes narrower and the recording capacity decreases (format efficiency decreases).

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide an optical recording medium having a high format efficiency.

[0009]

According to a first aspect of the present invention, there is provided an optical recording medium in which a servo area having a clock mark and data are recorded.
An optical recording medium in which data areas are alternately arranged,
Grooves are provided along the tracks in the data area
The position of the end of the groove corresponds to the address information.
At the changed position in the servo area.
It is characterized by that .

[0010] According to a second aspect of the invention, an unrecorded portion is reproduced.
The raw signal level is L0, and the reproduced signal at the beginning and end of the groove is
The signal level is L1 and the reproduced signal level of the groove portion is L2.
Then, the address code is reproduced from the optical recording medium having the relationship of L0>L1> L2.
An address detection device, comprising: a groove start end and a groove start end.
Address only the signal detected near the end reproduction signal level
It is characterized by having a means for outputting as a code.
You.

[0011]

[0012]

According to the optical recording medium of the present invention,
In the first invention, the data in the data area is highly dense.
The beginning or end of the groove to record each time
By changing, the address that indicates the address
It will act to be recognized as a Lesmark
You. Further, in the second invention, the groove starting end and
Address information can be uniquely identified from the playback signal level at the end.
The separation will be detected.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical recording medium according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic plan view of a main part of an optical recording medium according to a first embodiment of the present invention, and FIG. 2 is an overall plan view of the same. In this embodiment, a case where a phase change type optical recording medium is used will be described. A clock mark 1 is arranged in a servo area 11 on a track center line 10 shown by a dashed line in the same manner as in FIG. 7, and wobble marks 2a, 2b
Are displaced above and below the center line 10 with respect to the center line 10 as in the conventional example. The ends of the grooves (grooves) 3a, 4a, 5a are in the servo area, and the beginnings of the grooves 3b, 4b, 5b are also in the servo area.
The terminal ends are shifted by one clock unit. This state is, in other words, 3a ', 3b', 4a ', 4
It may be considered that there are concave address marks around the points b ′, 5a ′ and 5b ′, which are connected to the grooves of the data area and are integrated. The information is recorded in the groove in the data area 12 (outside the servo area). (Indicated by hatching in the figure.) Actually, as shown in FIG. 2, a disk-shaped recording medium substrate 7 is formed, and a plurality of servo areas 11 are provided at equal intervals radially from the center.
A data area 12 is arranged between the servo areas 11. Grooves (grooves) 3a, 3b are engraved along the spiral or concentric track center line 10 from the surface of the figure, and the clock mark 1, the wobble mark 2a, 2
b is also engraved, and a phase-change recording thin film 8 containing, for example, Te (tellurium) as a main component is formed thereon.
For example, it is formed by a method such as sputtering. It is assumed that the scanning light from the optical pickup is emitted from the back side of the drawing.

The operation of the optical recording medium of the present invention configured as described above will be described with reference to FIG. First, FIG. 3B based on clock mark 1
The synchronous clock signal shown in FIG.
The reproduction signal is sampled at C and D. In the waveform of the reproduced signal of the optical head shown in FIG. 3A, the grooves 3a and 3 in FIG.
The reproduction signal waveform when scanning the track including b is 31+
At 31 ', a reproduced signal waveform when scanning a track also including the grooves 4a and 4b is represented by 31 + 32', and a reproduced signal waveform when scanning a track also including the grooves 5a and 5b is represented by 32 + 32 '. In the reproduced signal waveform, the unrecorded portion is L0, the beginning and end of the groove are L1,
The groove portion is detected at the signal level of L2, and the recording information mark is detected at the signal level of L3. Here, since the optical pickup scans the optical recording medium shown in FIG. 1A with the laser beam from the rear surface, the signal waveform diagram 3A has the highest reflectance at the L0 portion,
The reflectivity of the groove portion L2 is low, and the laser beam having a certain diameter is applied to both the unrecorded portion having a high reflectivity and the groove portion having a low reflectivity at the beginning and end of the groove. As shown in FIG. 3A, the output gradually changes to produce an intermediate level L1. The output of L3 corresponding to the data recording portion 6 in which the signal is recorded by the phase change in the groove portion has the lowest output. The waveform of the reproduced signal in FIG. 3A is shown with the polarity inverted.

A description will be given with reference to FIG. 5 which is a block diagram showing a circuit for detecting the above-mentioned optical head reproduction signal, and FIG. In FIG. 5, one of the reproduced signals obtained from the optical head is applied to a clock generation circuit 51, which multiplies the signal detected for the clock mark 1 to generate a synchronous clock signal. The output of the clock generation circuit 51 is supplied to decoders 52a, 52b, 52
c and 52d, respectively, and A,
Pulses are generated at timings B, C, and D. The timing pulse outputs of the decoders 52a, 52b, 52c and 52d are supplied to sample holders 53a, 53
In addition to 3b, 53c and 53d, the optical head reproduction signal input is sampled and held at timings A, B, C and D in FIG. Then, the sample holders 53a, 53b,
The outputs of 53c and 53d are compared with comparison circuits 54a,
In addition to 54b, 54c and 54d, the level of the sample hold signal is determined at timings A, B, C and D in FIG. FIG. 6 shows a specific example of the comparison circuit 54a. In FIG. 6, an input signal is applied to the (−) terminal of the differential amplifier 541a and the (+) terminal of the differential amplifier 542a, and (L1 + L2) / 2, Since a comparison voltage of (L0 + L1) / 2 is applied to the (-) terminal of the amplifier 542a, the input signal is larger than (L0 + L1) / 2 [middle of L0 and L1] and is larger than (L1 + L2) / 2. The differential amplifier 541a and the differential amplifier 542a provide an output to the AND circuit 543a only when
That is, the comparison circuit 54a sets 1 and 0 otherwise.
Occurs. Comparing circuits 54b, 54c and 54d perform similar operations and output them as address codes.

Here, the address code is, for example, L1
Assuming that the signal detected at step (1) is “1” and the signal detected at other levels is “0”, the groove configuration of FIG. Is obtained, and can be detected as a 4-bit address. Of course, this is not limited to 4 bits.

As described above, according to the first embodiment, the position of the end of the groove for high-density recording in the data area can be changed in the servo area without particularly providing an address mark. The same effect can be obtained as if address marks were provided by skillfully utilizing the space in the servo area, and the recording density could be further increased.

In the embodiment, the groove which enters the servo area from the data area is provided at the rear end of the front data area and the front end of the rear data area. However, the groove is provided only at the front end of the rear data area. Alternatively, it may be arranged not to enter the servo area from the beginning, or may be provided only at the rear end of the previous data area, and not enter the servo area from the rear data area.

In this embodiment, as shown in FIG. 2, grooves (grooves) 3a and 3b are formed in the disk-shaped recording medium substrate 5 from the surface of the drawing, and the clock mark 1 and the wobble marks 2a and 2b are also formed. And
The scanning light from the optical pickup is irradiated from the back side of the paper surface. Conversely, the land rises from the surface shown in the figure, and the clock mark 1 and the wobble marks 2a, 2
b also has a convex shape, and the scanning light from the optical pickup is similarly recorded, even if it is irradiated from the back side of the paper.
Can be played.

Further, the positional relationship between the clock mark and the wobble mark is not limited to the example, and the arrangement may be changed as appropriate.

Further, in this embodiment, the phase change type optical recording medium has been described. However, the present invention may be applied to a magneto-optical recording type recording medium. However, in that case, the detection method may be changed according to the medium.

Next, a read-only optical recording medium according to a second embodiment of the present invention will be described with reference to the drawings. In FIG. 4 of a schematic plan view of a main part of a read-only optical recording medium,
Address marks 40a, 4a
0b is formed on both sides of the clock mark 1 in isolation. The pre-pit mark 41 is formed in the data area 43 in advance. The outer shape is, as a matter of course, a disk shape as in the case of FIG.

As described above, according to the second embodiment, the recording / reproducing type having a groove and the data arrangement in the servo area 42 have exactly the same positional relationship, so that the optical recording medium of FIG. 1 can be reproduced. The optical reproducing apparatus has medium compatibility, and can realize a read-only optical recording medium of a compatible format. However, for the sake of compatibility, during reproduction, the configuration of the comparison circuit shown in FIG. 6 is slightly changed so that the output of the front end of the address mark following the rear end of the data area and the rear end of the address mark preceding the front end of the data area are output. Even if there is, it is necessary to make the configuration that ignores it.

[0024]

As described in the foregoing, Guru optical recording medium of the present invention, in its first, second invention, the servo area having a clock mark, etc., on which data is recorded
A groove is provided along the track, at the beginning of the groove.
Depending on the amount that the end or the end enters the servo area
By expressing the address as
In addition to using grooves that are suitable for density recording,
Address by effectively using the start or end of
Thereby, the recording density can be further increased .

Further, the third invention is an alternative to the above-mentioned groove.
By forming data pits in the
Media can be realized. Further, the fourth invention
Is detected near the playback signal level at the beginning and end of the groove.
Only output signals are output as address codes
To separate and detect the address code from other information
Can be.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a main part of an optical recording medium according to a first embodiment of the present invention.

FIG. 2 is an overall plan view of the same.

FIG. 3A is a waveform diagram showing an output signal when an optical recording medium is scanned by an optical pickup, and FIG. 3B is a waveform diagram of a synchronous clock signal.

FIG. 4 is a schematic plan view of a main part of an optical recording medium according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a circuit for detecting an optical head reproduction signal from the optical recording medium according to the first embodiment of the present invention.

FIG. 6 is a block diagram of a comparison circuit of a main part of the same.

FIG. 7 is a schematic plan view of a main part of a conventional optical recording medium.

[Explanation of symbols]

 1 clock mark 2a, 2b wobble mark 3a, 3b, 4a, 4b, 5a, 5b groove 6 data recording portion 10 track center line 11 servo area 12 data area

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-50933 (JP, A) JP-A-63-53760 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/00-7/013 G11B 7/28-7/30 G11B 20/10-20/16 G11B 27/10-27/34

Claims (4)

(57) [Claims] A servo area having a clock mark;
Light in which data areas for recording data are arranged alternately
A recording medium, wherein the data area is provided along a track.
A groove is provided, and a position of an end of the groove is provided.
Changes in the servo area according to the address information.
An optical recording medium , wherein the optical recording medium is provided at a predetermined position . 2. The starting position and the ending position of the groove are one click.
2. The method according to claim 1 , wherein the value is specified in lock units.
The optical recording medium according to the above. 3. A reproduction signal level of an unrecorded portion is set to L0,
The playback signal level at the beginning and end of the groove is L1, the groove
When the reproduction signal level of the portion is L2, L0> L1> L2 Reproduction of address codes from optical recording media
An address detection device, It is detected near the reproduction signal level at the beginning and end of the groove.
A means to output only the output signal as an address code
An address detection device, comprising: 4. A reproduction signal level of an unrecorded portion is L0, a reproduction signal level of a groove start and end is L1, a reproduction signal level of a groove portion is L2, and a reproduction signal level of a recording information mark is L3. An address detecting device for reproducing an address code from an optical recording medium satisfying a relationship of L1>L2> L3, wherein a means for outputting as an address code only a signal detected near a reproduction signal level at the start and end of the groove is provided. An address detection device characterized by the above-mentioned.