JP2812321B2 - Disk-shaped recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk-shaped recording medium suitable for application to, for example, a magneto-optical disk.

[0002]

2. Description of the Related Art In an optical recording medium, for example, a magneto-optical disk, a guide groove for tracking is previously formed in a spiral or concentric shape on the disk, and the guide groove (so-called groove) formed in advance or A structure has been developed in which a land portion between grooves is used as a recording track, and data is recorded and reproduced on the recording track using the magneto-optical effect along the track direction.
Such a recording medium magneto-optically records and reproduces data while optically detecting the guide groove and applying tracking servo.

Meanwhile, in a recording medium having such a groove as a recording track, the groove is previously displaced in the width direction at a predetermined interval at the time of molding the disc, and control information such as address information and synchronization information is transferred by the displacement in the width direction. It is proposed to keep a record. For example, as shown in FIG. 4, grooves a provided along the scanning direction of the optical head are scanned at intervals based on digitized address information or at intervals based on a synchronization signal required for reproduction. It is slightly displaced in the width direction perpendicular to the direction. When data is recorded in the groove a, the polarity in the groove is changed by the magneto-optical effect regardless of the displacement in the width direction to record various data. The signal recorded in the groove by the magneto-optical effect is hereinafter referred to as an MO signal. By doing this,
Control information such as address information and synchronization information is recorded efficiently.

[0004]

However, when the groove is displaced in the width direction as described above, the edge portion e which is the point of displacement in the width direction of the groove adversely affects the reproduction of the MO signal recorded in the groove. There was a fear. That is, for example, when the edge portion of the MO signal and the edge portion e due to the displacement in the width direction are close to each other, there is some influence such that it is difficult to accurately determine the edge portion of the MO signal.

An object of the present invention is to prevent the displacement of the groove in the width direction from adversely affecting recorded data reproduction.

[0006]

According to the present invention, there is provided a disk-shaped recording medium in which data modulated based on a predetermined channel clock cycle is recorded on a recording track along a track direction. The data to be transmitted is composed of a plurality of frames each including a frame synchronization signal having a period that is an integral multiple of the channel clock period and modulation data following the frame synchronization signal. And a frame synchronization signal section which is displaced to

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIG.
This will be described with reference to FIG.

FIG. 1 shows the formation of recording tracks on a magneto-optical disk formed according to an embodiment of the present invention. The magneto-optical disk of this embodiment in which the tracks are formed is formed by forming a perpendicular magnetization film having a magneto-optical effect on a transparent substrate, and a guide groove for tracking is formed on the magneto-optical disk. ) Are formed in advance in a spiral or concentric manner, and these grooves are used as recording tracks (the tracks are shown as straight lines in FIG. 1). In this case, in this example, various data as control information is recorded in advance in the groove at the time of forming the disk by displacement in the width direction. As the control information recording format, a so-called C for recording a digital audio signal or the like is used.
It is assumed that the recording format conforms to the recording format of D (compact disc). That is, in the general CD format, one block (one sector) serving as an information recording unit includes 98 frames from the 0th frame to the 97th frame. FIG. 2 shows the structure of each frame. One frame is 588 times the channel clock period T (588 times).
T) In one frame, each recording area for a frame synchronization signal, a subcode, and data (including parity) is provided. Also, at the beginning of one frame, 24T
(24 channel bits) frame sync signal and 14T
Are connected via 3T connection bits, and data and parity of 32 symbols (32 bytes) are modulated by the so-called EFM (8-14 modulation) method in the remaining 544T. It has been arranged.

The data modulation according to the EFM system converts an original symbol from 8-bit data into a 14-bit pattern, and sets each symbol so that the connection state between the 14-bit patterns satisfies a predetermined condition. Three connection bits (merging bits) are inserted between them. As the three connection bits, four patterns of 000 100 010 001 are prepared, and one of the patterns is selected according to the preceding and following data. The DC component of the recording signal is controlled by inserting the connection bit, and the connection bit itself does not contain information.

Here, returning to the description of the magneto-optical disk according to one embodiment of the present invention, the grooves provided on the magneto-optical disk of this embodiment have E
The data modulated by the FM method is recorded. In this case, one block (one sector) is changed from the 0th frame to the 99th frame.
Data is recorded in 98 frames from the first frame to the 98th frame, with 100 frames up to the frame.
The 0th frame and the 99th frame are used as recording areas for address signals and synchronization signals in block units. And the first
From the frame to the 98th frame, the data and parity recorded following the frame synchronization signal area, the subcode area, and the connection bits before and after the frame synchronization signal area consist of 32 symbols, each symbol being a 14-bit pattern and a 3-bit pattern. Consists of connection bits.

In this embodiment, the first to 98th frames for recording this data are preliminarily displaced in the width direction by (22T × 2 + 17T × 32) in each groove 1 as shown in FIG. Keep it. In this case, the width direction displacement at a period of 22T is information as a frame synchronization signal, and the width direction displacement at a period of 17T is information for clock generation and synchronization pull-in. When data modulated by the EFM method by the magneto-optical effect is recorded in the groove 1, the frame synchronization signal, the subcode, and the connection bits before and after the subcode are recorded in a portion where the first 22T continues twice. In this case, as the frame synchronization signal, for example, a signal in which 11T continues twice is recorded in the same manner as the frame synchronization signal of a CD. Incidentally, 11T is the maximum inversion interval T _MAX of the EFM method. Then, in the data and parity recording area of 32 symbols, the data is recorded such that the displacement point (edge) 1a of the groove 1 whose width is displaced every 17T coincides with the recording area 1b of the data and parity connection bits. At this time, for example, a substantially central portion of the connection bit recording area 1b in which three bits are recorded becomes the edge 1a.

Next, FIG. 3 shows a configuration of a recording / reproducing apparatus for reading data recorded in the groove 1 formed in this way. The recording / reproducing apparatus shown in FIG. 3 is capable of reproducing a magneto-optical disk having grooves 1 formed thereon and reproducing a CD having pits formed as tracks (or a CD-ROM having a similar format). 3
In the data 11, the data recorded due to the physical change of the track (formation of pits and displacement of the groove width) is R
A terminal which is read and supplied as an F (high frequency) signal,
Reference numeral 12 denotes an MO recorded in the groove by the magneto-optical effect.
A terminal from which a signal is read and supplied.
The signals supplied to 1 and 12 are supplied to first and second fixed contacts 31 and 32 of the changeover switch 3. The switching of the changeover switch 3 is controlled by a changeover control signal supplied to a changeover control signal input terminal 20 together with a changeover switch 4 described later. Then, the RF signal or the MO signal obtained at the movable contact 33 of the changeover switch 3 is supplied to the binarization circuit 13, which converts the RF signal and the MO signal to a high-level signal "1" or a low-level signal. The signal is converted into binary data of the signal “0”. Then, the binary data output from the binarization circuit 13 is transmitted to the synchronization detection circuit 14, the demodulation circuit 16, and the PLL.
Supply to circuit 18. The synchronization detection circuit 14 detects a frame synchronization signal recorded at the head of each frame based on a clock supplied from the PLL circuit 18 side,
The detected synchronization signal is supplied to the rotation control circuit 15 of the disk, and the rotation speed servo is applied.

The demodulation circuit 16 demodulates data recorded in each frame based on a clock supplied from the PLL circuit 18 and converts the demodulated data into an error correction circuit 1.
7

The PLL circuit 18 includes a binarizing circuit 1
3 generates a clock of 4.3218 MHz based on the reproduced data output from
And the output clock is supplied directly to the second fixed contact 42 of the changeover switch 4. And this changeover switch 4
The signal obtained at the movable contact 43 is supplied to the synchronization detection circuit 14. The output clock of the PLL circuit 18 is directly supplied to the demodulation circuit 16.

The switching control signal obtained at the switching control signal input terminal 20 includes both movable switches 3 and 4 when the magneto-optical disk having the groove formed therein is accessed (recording and reproducing). A signal for connecting the first fixed contact to the first fixed contact is supplied. Also,
The recorded data (M
At the time of reproduction (O signal), both the changeover switches 3 and 4 supply a switching control signal for connecting the movable contacts 33 and 43 to the second fixed contacts 32 and 42. In addition, the pit formed C
When reproducing D, a switching control signal for connecting the changeover switch 3 to the first fixed contact 31 and connecting the changeover switch 4 to the second fixed contact 42 is supplied.

Next, the operation of the recording / reproducing apparatus shown in FIG. 3 will be described. First, a groove 1 as shown in FIG.
The recording and reproduction of the magneto-optical disk on which is formed will be described. When recording data on this magneto-optical disk, the movable contacts 33 and 43 of the changeover switches 3 and 4 are both fixed to the first fixed position by the above-described changeover control signal. Contact 31,
41, and a portion where the first 22T of each frame recorded by the displacement in the groove width direction continues twice is detected. That is, since the 4.3218 MHz clock output from the PLL circuit 18 is supplied to the synchronization detection circuit 14 after being divided by １ ／, the 22T clock recorded by the groove width displacement is output.
(22T is the frame synchronization signal 11T in the CD format)
2 times the frame synchronization signal is detected by the synchronization detection circuit 14.
And the disk rotation can be synchronized. In this state, E
Data modulated by the FM system is recorded as an MO signal (the recording system circuit is omitted). In this case, in the data and parity recording area of each frame, as shown in FIG.
Data is recorded so that the width-direction displacement point (edge) 1a of the groove 1 that is displaced every 7T coincides with the connection bit recording area 1b for data and parity.

At the time of reproduction of the magneto-optical disk, as in the case of recording, first, a frame synchronization signal of 22T recorded by the displacement of the groove is detected and access is performed, and then switching is performed by the above-described switching control signal. Switches 3, 4
In both cases, the movable contacts 33 and 43 are connected to the second fixed contacts 32 and 42, and an 11T frame synchronization signal recorded as an MO signal is detected and reproduction is performed. In this case, the 4.3218 MHz clock output from the PLL circuit 18 is supplied to the synchronization detection circuit 14 as it is.
Can be detected.

When reproducing a CD on which pits are formed, the changeover switch 3 is connected to the first fixed contact 31 and the changeover switch 4 is set to the second fixed contact by the above-mentioned changeover control signal. 42, so P
The 4.3218 MHz clock output from the LL circuit 18 is supplied to the synchronization detection circuit 14 as it is to detect and reproduce an 11T frame synchronization signal formed as a pit.

As described above, according to the present embodiment, as a recording / reproducing apparatus, a circuit can be shared between a magneto-optical disk having grooves and a disk such as a CD having pits. In this case, the frame synchronization signal recorded by the displacement of the groove in the width direction has a period of 22T and is an integral multiple of the frame synchronization signal (11T) of the signal modulated by the EFM method. Can easily detect synchronization. The data and parity recording area of each frame formed in the groove of the magneto-optical disk is
Since the groove is displaced in the width direction of the symbol every 17T, the recording data can be searched for one symbol (one byte). Since the interval (22T) of the frame synchronization signal is longer than the displacement in the width direction at every 17T, the frame synchronization signal can be reliably detected. Further, since the connection bit portion is set to the position corresponding to the displacement point in the width direction of the groove in the data and parity recording area of each frame, at the time of reproducing recorded data (MO signal),
The point of displacement in the width direction of the groove has no adverse effect,
Good data reproduction can be performed. That is, the connection bit part is DC
The component is controlled, the connection bit itself does not contain information, the 14-bit data recording portion does not overlap the displacement point in the width direction, and the displacement in the width direction does not affect the data reproduction.

In the above-described embodiment, the so-called groove recording in which data recording on the magneto-optical disk is set in a groove is performed. However, the so-called land recording in which data recording is performed on a land portion between adjacent grooves is performed. You may do it. Further, in the above-described embodiment, the edge is almost at the center of the connection bit recording area where three bits are recorded. However, any one of the connection bit recording areas may coincide with the edge. Further, the present invention can be applied to various recording media such as, for example, organic dye-based optical disks, various write-once disks, overwritable disks, optical cards, and magneto-optical cards, in addition to the magneto-optical disks shown in the above embodiments. Furthermore, the present invention is not limited to the above-described embodiment, but may take various other configurations.

[0021]

According to the present invention, data recorded on a disk-shaped recording medium in which data modulated based on a predetermined channel clock period is recorded on a recording track along the track direction is converted to a channel clock period. A frame synchronization signal comprising a plurality of frames each including a frame synchronization signal having an integral multiple period and modulation data following the frame synchronization signal, and displacing a track in the width direction with a repetition period of an integral multiple of the frame synchronization signal. The provision of the section makes it easier to synchronize the data input / output during recording and reproduction with the rotation of the disk. For this reason,
The circuit configuration of a device that performs recording and reproduction using this recording medium can be simplified. Further, by using this recording medium, there is an effect that the frame synchronization signal can be reliably extracted from the displacement component in the track width direction.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a track formation state according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a modulation state according to the EFM method.

FIG. 3 is a configuration diagram showing a circuit configuration of a recording / reproduction device according to an embodiment.

FIG. 4 is a schematic diagram illustrating an example of a conventional recording medium.

[Explanation of symbols]

1 groove, 1a edge (width direction displacement point), 1b
Connection bit, 14 synchronization detection circuit, 16 demodulation circuit, 1
8 PLL circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/24 561 G11B 7/00-7/007 G11B 11/10 511

Claims (1)

(57) [Claims] 1. A disk-shaped recording medium on which data modulated based on a predetermined channel clock cycle is recorded on a recording track along a track direction, wherein the data to be recorded is an integer of the channel clock cycle. The track is composed of a plurality of frames each including a frame synchronization signal having a double cycle and modulation data following the frame synchronization signal. Disk-shaped recording medium having the same.