JPH1097719A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reading omission during accessing in high-speed movement so as to improve the reliability of address detection by disposing a plurality of bit patterns between tracks among address information most significant bits after a synchronous mark. SOLUTION: After the synchronous mark sync pattern of a synchronization region, a least significant bit B0 is disposed from an address information most significant bit B13. Here, the bit pattern of minimum high-order 9 bits is disposed between tracks. Thus, reading omission is prevented during high-speed movement for accessing and the reliability of address detection is improved. Also, if the number of blocks is small and the number of speed control sample values is small, low-order 5 bits are disposed to be shifted from an original prepit position by using left and right meandering bits. Thus, even for an optical disk to be overwritten, a tracking signal and a clock signal are reliably detected from the prepit meandered left or right. Further, track shifting caused by disk inclination or optical spot movement is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc, and particularly to a format suitable for recording and reproduction.

[0002]

2. Description of the Related Art Heretofore, there has been known a method of recording data between prepits by using prepits meandering minutely to the left and right as a tracking method (Japanese Patent Laid-Open Publication No. Sho 56 (1988)).
-3439).

[0003]

In this conventional example, a tracking operation is disclosed. For recording and reproduction, only a write-once medium is described. However, recently, reversible media have been developed as optical disc media, and overwritable media have received particular attention. Promising among them is an overwriting method using magnetic field modulation. When an optical disk device is to be configured using this method, it is necessary to reconfigure the tracking method and to adopt a configuration that operates as a device, such as an access method and data recording / reproduction. Conventionally, there has been no proposal of such an overall configuration. There are the following issues as viewed from such a system.

When a medium that can be overwritten is used as a medium, the timing of a domain formed at the time of recording deviates from that of a recording pasta.

When the signal amount of the magneto-optical signal is compared with the signal from the pre-pit, the pre-pit signal leaks into the magneto-optical signal because the signal amount from the pre-pit is large.

A means for reliably detecting the meandering phase of the prepit is required.

For access, a means for detecting the position information of the light spot from the disk surface is required.

[0008]

According to the present invention, self-clocking is used as a data clock generation method.

Regarding the problem described above, an empty area is provided between the data recording area and the prepit.

[0010] With respect to the problem described above, a pattern not present in the prepit pattern or a pattern not present in the data pattern is provided in advance together with the prepit as a synchronization mark. Then, this is recognized at the time of reproduction.

In order to solve the problem, a special pattern for access is provided on the disk surface so that the track address can be substantially detected only by passing the light spot through the track, and this is provided in advance in the synchronization area together with the synchronization mark. . In order to detect finer track position information, the position of a meandering pit or the position of a special pit is changed.

[0012]

[Action] The difference between the recording pulse and the formed domain is as follows.
Since it is constant within the same sector, self-clocking can absorb this shift.

By providing an empty area, interference between prepits and magneto-optical signals can be reduced.

Even if data and pre-pits exist, a synchronous pattern can be detected with high reliability.

The position information of the light spot can be detected directly from the disk surface, and the actuator can be controlled to access a target track at a high speed.

The above-mentioned operations are combined to realize an optical disk drive.

[0017]

An embodiment of the present invention will be described below with reference to FIG. For the magnetic field modulation overwriting method, see JAPAN
ESE JOURNAL OF APPLIED PH
YSICS Vol. 26 (1987) Suppl. 26
-4, pp. 149-154, and the optical system for recording and reproduction is described in pp. 117-12 of the same book.
Since the operating principle is described in FIG.
A system configuration as an optical disk device will be described.
In FIG. 1, a disk 1 is driven by a rotary spindle 2 and a magnetic head magnetic coil 3 is provided on the disk surface.
, And float above the disk surface with a gap of several microns. An optical head 4 is placed facing the magnetic head, and a light spot from the optical head is positioned in a magnetic field region generated by the magnetic head. The signal detected by the optical head 4 enters an arithmetic processing circuit 10, where it is divided into a magneto-optical signal and a signal from a pre-pit. The magneto-optical signal enters a data demodulation circuit 11, where a reproduction clock RCK and a gate signal indicating the location of the data are provided. The signal is demodulated by the RDT and sent to the data controller 15.

The pre-pit signal from the arithmetic processing circuit 10 first enters a clock generation circuit 12, where clocks RCK and WCK necessary for data recording / reproduction and tracking are provided.
Create The pre-pit signal enters a track shift detecting circuit 14 and generates a track shift signal TE using a control signal from the timing generating circuit 13. Further, the pre-pit signal enters the timing generation circuit 13 and uses the clock signal from the clock generation circuit 12 to control signals for detecting track deviation, control signals for detecting position information for access, and recording / reproduction. A signal or the like for controlling data is generated and sent to the track shift detection circuit 14, access controller 16 and data controller 15, respectively.

A signal from a pre-pit is input to the access controller 16 and the timing generation circuit 13
The information indicating the position of the light spot is detected by using the signal from Further, a signal from the track shift detecting circuit 14 is input to detect minute track information. Based on these signals and a target track number (input via the bus 18) specified by the host CPU 17, command information FA and CA for controlling the two actuators is transmitted.

The reproduced data processed by the data controller 15 is sent to the host CPU 17 via the bus 18. On the other hand, data to be recorded is sent from the upper CPU 17 to the data controller via the bus 18 and the ECC
After adding control data such as (23-correction code) and performing processing such as interleaving, the data is sent to the data modulation circuit 20. In this circuit, data pulses to be actually recorded on a disk surface are created using signals WCK and WDT from a clock creation circuit 12 and a timing generation circuit 13. According to this signal, the coil driver 7 is driven,
Modulate the magnetic field. The power of the spot on the disk surface is controlled by the laser drive circuit 6, and this timing is synchronized with a signal WRC from the host CPU 17 indicating the recording / reproducing state.

A part of the detection signals from the optical disk 1 is input to a focus error detection circuit 19 to create a control signal AF for an auto-focus servo system, which is input to a light spot control circuit 9 for phase compensation and the like. After performing the optical head 4
, And focus control is performed. The track deviation signal TE is input to the light spot control circuit 9, and after processing such as phase compensation, a signal for controlling the fine actuator and the coarse actuator is created. The coarse actuator control signal drives the coarse actuator 5 through the coarse drive circuit 8,
The entire head is moved in the disk radial direction.

A signal FA from the access controller is input to a light spot control circuit 9 for controlling a fine actuator (not shown) in the optical head 4 to enable a fine and high-speed control of a light spot at the time of access. . further,
The signal CA is input to the coarse drive circuit 8 and controls the macro movement of the entire optical head at the time of access.

A signal WRC indicating recording / reproduction is input to a clock generation circuit 12 and a timing generation circuit 13, and controls respective output signals according to a recording / reproduction state.
The above is the overall configuration of the optical disk device according to the present invention.

Next, the pre-pit shape will be described with reference to FIG. Each track on the disk surface is provided with a repeated pit pattern for each data division unit and each lid. In this sector, an ID section having address information and other control information is provided at the head, and prepits meandering by a small amount to the left and right with respect to the center of the track are arranged. Data is recorded during this pre-pit. In the conventional method, a pit pulse indicating a pit position is created from the pre-pits as shown in FIG. 4, and a clock signal for recording and reproducing data and a track shift signal are simultaneously detected from the pit pulse. FIG. 3 shows a specific waveform of the track shift signal. As the meandering state of the prepits, there are an in-phase pit and a phase inversion pit as shown in FIG. Servo operation OF for these pit patterns
5 shows a track shift signal at F and a following state when the servo operation is ON.

For the data, a clock signal synchronized with the pit pulse shown in FIG. 4 is created, the recording data is modulated using this clock, and the data area between the pre-pits is recorded. In the magnetic field modulation overwrite method, the formed magnetic domain has a strip shape as shown in FIG. Also in the case of reading this, the clock created from the pre-pit has been conventionally used. This has the following problems. That is, in FIG. 5, by the irradiation of the data pulse,
The temperature distribution on the surface matches the intensity distribution of the light spot,
The distribution is such that a tail is trailed by Δ1 behind the light spot. According to the principle of magnetic field modulation overwriting, a point on the disk surface where the temperature is lower than the Curie temperature is recorded according to the magnetization direction of the external magnetic field. Therefore, assuming that the temperature falls below the Curie point at a point shifted by Δ2 from the center of the distribution, Δ3 between the edge of the data pulse and the edge of the recording domain is Δ3, which is the sum of Δ1 and Δ2.

From the above, in the magnetic field modulation overwrite method, the recording pulse and the domain deviate in principle. However, although this deviation amount depends on the irradiation power, the linear velocity, the disk sensitivity, and the like, it is considered that it is almost constant within the same sector and each domain does not change. For this reason,
As a reproduction clock generation method, a self-clocking method of generating a clock from data is employed.

There is another problem. When the magneto-optical signal and the signal from the prepit are detected by the difference and the sum of the two polarization components as described later, the intensity ratio of the two signals is 1: 1.
There are about 50 to 100, and the pre-pit signal leaks into the magneto-optical signal. For example, the spot diameter is 1.5 μm again.
Assuming that φ and the prepit diameter are 0.6 μmφ, the prepit signal becomes equal to the magneto-optical signal at a distance of about 1.3 μm, and considering the signal detection margin, the data is separated by about 2 to 2.5 μm from the center of the pit. Must be kept. Therefore, 4-5 μm around the pre-pit
An empty area of about m is provided.

Further, when the pits are differentiated to detect the position of the pre-pit, an erroneous signal is generated due to noise, defects, etc. on the disk, an erroneous signal is generated from the pre-pit position, and a track shift signal is mistaken. There is. In addition, it is necessary to know the phase of meandering in order to detect a track shift signal. For this purpose, a synchronization mark is formed on the disk in the form of a pre-pit in advance, and the synchronization mark is detected to determine the meandering phase and to identify the position of the pre-pit.

FIG. 6 shows a track format considering the above. One track includes N sectors, one sector includes M blocks, and one block includes l prepit pair areas. One pre-pit pair area includes pre-pits, an empty area sandwiching the pre-pits, and a data area. Taking a 3.5 optical disk as an example, the number of data bytes in one track is 18 KB in unformat, the number of sectors N is 20 to 24, and M is 20 to 40.
L is about 8 to 16. Also, the number of pre-pits / track related to the tracking servo and clock generation capability is about 6,000 to 3,000.

As a modulation method, a fixed length code is preferable because data is cut at a fixed length. There are 8/9 conversion, 4/5 conversion, a certain 2-7 modulation method and the like that can be self-clocked by such a modulation method. However, a variable length code is also applicable in consideration of recording density efficiency.

Among them, the 2-7 modulation and the 1-7 modulation are excellent methods, and the 2-7 modulation has an advantage from the viewpoint of density, and the 1-7 modulation has an advantage from a detection margin. In a recording / reproducing system such as a magneto-optical disk having a strict S / N and a small amplitude deterioration at a used data frequency, 1-7 modulation having a sufficient detection margin is advantageous.

As a recording method, there is a pit position recording as shown in FIG. 6 or an edge recording as shown in FIG. The pit position recording does not require special consideration for the modulation method, but the recording density is lower than that of the pit edge recording.
In pit edge recording, since the data has a fixed length, there is a restriction that the starting point and the ending point of the recording data must match one of the recording levels. To avoid this, add an additional bit according to the data before modulation so that the end point of the data after modulation always matches one of the recording levels, or add an additional bit to the data after modulation and record it. You have to do the same level.

7 and 8, a method of processing a detection signal using this format will be described. When the light spot 70 on the disc 1 passes through the tracks 71 and 72, the reflected light passes through the voice coil lens 21 and the galvanomirror deflector 34, is partially reflected by the beam splitter 30, and is reflected by the beam splitter 33. The luminous flux is further separated, and one part is defocus detection system 19.
to go into. The other component is split by a deflection beam splitter 36 through a half-plate 35 to be deflected by a lens 3.
By means of 7 and 39, they are focused on a detector 40 respectively. By adding and subtracting the signals from the detectors 38 and 40, respectively, the pre-pit and the reflected light from the disk can be detected from the sum signal, and only the magneto-optical signal component can be obtained from the difference signal. The sum signal 73 changes corresponding to the pre-pits as shown in FIG. 8 by passing through the pre-pits 74 to 83. This signal 73 is passed through an amplifier 41 to a reduction filter 42 for removing high-frequency noise, and its output is differentiated by a differentiating circuit 43. The differentiated signal 88 is compared at a certain threshold by the comparator 44 to obtain a signal 89, which is expanded in pulse width by the mono-multivibrator 45 to obtain a signal 90, and a signal 91 at the zero crossing point of the differentiated signal 88. Is obtained by the cross point detection circuit 46, and a logical AND with the signal 90 is obtained to obtain a pit signal 92 indicating only the pre-pit portion. The signal 92 is input to the shift register 48, and the specific clock 47
The pit signal is time-shifted, and the pre-pits 86, 87,
And the pre-pits 86, 87 from the time interval between 77 and 82.
The synchronization timing 93 is generated from the delay time of the register 48. A pit signal 92 is input to a PLL (phase, locked loop) 49 for generating a clock, and a clock WC synchronized with the pit signal is input.
Generate K. This signal WCK is input to a frequency dividing circuit 50 composed of a counter, and an estimated pulse 94 is generated at a pre-pit period in accordance with the timing at which the pre-pit exists. The start timing of the counter 50 is determined by the above-described synchronization timing 93. The signal 94 is input to the flip-flop 53 to generate a signal having a period twice as long as the period of the pre-pit.
1, φ2, which is timing information corresponding to the position of the pit on the left or right side of the track center.
Further, the clock signal WCK is input to the frequency dividing circuit 51 composed of a counter, and the start timing of the counter is set by the signal 94 so that a pulse is generated just in the middle of the pre-pit.
2 to signal φ3.

The outputs of the reduction filter 42 are input to sample and hold circuits 57 and 58, respectively, and sample and hold are performed by signals φ1 and φ2, respectively. The respective outputs are input to a differential amplifier 59, and a difference is obtained. Although this output can be used as a track shift signal, the signal passed through the inverting circuit 60 and the signal as it is are input to the respective inputs of the analog switch 61, and this signal is inverted by the signal φ3 and the inverter 62. , The sampling frequency for detecting the track deviation can be effectively doubled.

The pre-pits 86 and 8 are used as synchronization patterns.
As shown in FIG. 9, a specific pattern having a time arrangement which is not in the meandering pre-pit row may be used, but as shown in FIG.
Elongated hole patterns 95 and 96 not included in the data may be used. Also, the slots can be arranged between the tracks. Similarly, patterns of pits 84, 85, 86, 87 can be inserted between tracks. In this way, the synchronization mark can be detected even if the light spot is between the tracks. Further, in consideration of future applications of optical discs, it is necessary to reproduce the write-once discs which have been used up to now even with this apparatus. At this time, the data is detected from the sum signal, and becomes a signal at the same level as the track shift signal and the synchronization mark. To be able to distinguish the sync marks,
A pit pattern that does not exist in the recording data may be selected.

The data modulation will be described. The difference signal is converted into a digital signal by the binarization circuit 54 and input to the phase comparator 55. The other input is PLL4
The phase shift circuit 56 is controlled by an output of the phase comparator 55 by inputting a signal obtained by shifting the phase of the clock WCK from the clock 9. In this way, even if there is a domain shift at the time of recording, it is possible to synchronize only with the recording data by moving only the phase. The reproduction block RCK is input to the demodulation circuit 11 and the data is demodulated. With this configuration, since the clock WCK synchronized with the pre-pit is used at the time of recording, recording can be performed without being affected by disc eccentricity and rotation fluctuation.

On the other hand, during reproduction, in synchronization with the pre-pits,
A clock having the same frequency as that of the recording data is detected without being affected by disk eccentricity and rotation fluctuation. Here, if only the phase shift is detected from the data and the phase is adjusted, a reproduced clock RCK synchronized with the data can be obtained.

Another embodiment for generating a reproduction clock will be described with reference to FIG. Signal φ4 is converted to F / V converter 1
01, the frequency is converted to a voltage, and then compared with a reference speed voltage by a differential amplifier 102, and the difference is input to an adder 104 via a phase compensation circuit 103. The other side of the adder 104 includes a voltage-controlled oscillator 10
5 is detected by the phase comparator 107, and the result of passing this output through the phase compensating circuit 106 is input. In this case, 2
It is a control system with one input and one output. This loop is composed of an F / V system and a normal PLL phase control system, and its loop characteristics are desired to have a configuration as shown in FIG. Since the F / V system has inertia, the crossover frequency fc2 is not selected to be about 2 to 5 kHz. The phase control system has a frequency of several hundred KHz in normal self-clocking. However, if the band is expanded in this way, the influence of noise is large.
It is desirable to set it to ５０50 KHz. In this way, the reproduced clock does not run away due to a defect or the like, and the jitter due to miscellaneous length is reduced as compared with a normal self-clock. And the tracking characteristic is improved.

Next, a format for access will be described with reference to FIGS. For access, it is necessary to always correctly detect the position even if the moving speed of the light spot changes from high speed to low speed. 3.5 "
In the case of an optical disk, the track pitch is 1.5 to 1.4 μm
Then, the number of tracks becomes 15,000 to 11,000, and 14 bits can be sufficiently expressed. The embodiment will be described below with this number of bits.

In this format, as a basic configuration, address information is put into a synchronization area together with a synchronization mark.
For example, as shown in FIG. 11, after the synchronization mark (represented by an X mark in the figure), the most significant bit B13 to the least significant bit B0 are inserted. However, in the basic configuration, when moving at a high speed during access, for example, at 1 m / sec, there is a high probability that the light spot passes through the track before reading all the bits while moving.

Therefore, as shown in FIG.
The bit pattern of the bits is arranged between the tracks. That is, since the uncertainty of the number of 5 bits passing at the maximum speed always remains, higher bits can be reliably detected during high-speed movement. During high-speed movement, speed control at the time of access can be sufficiently performed using only the upper bits. Regarding the lower bits, the reliability of the track address detection is improved by arranging the pre-pits between the tracks as shown by the dotted line.

In the embodiment shown in FIG. 11, 14 bits are required for the address, and this cannot be applied when there is not enough room in the number of data that can be recorded in the synchronization area. Therefore, FIG.
The upper 9 bits are distributed one bit at a time in the synchronization area of 9 blocks, and the lower 5 bits are arranged in the synchronization area of each block. In this case, the upper bit becomes 9
The detection can be performed only after reading the block, but control can be performed at a certain speed. If there are many 9 blocks, it is sufficient to disperse them by 2 bits or 3 bits.

In the embodiment of FIG. 12, when the number of blocks is large, it is good. However, when the number is small, the sample value of the speed control becomes small, so that it becomes unstable, and high-speed seek becomes difficult. Therefore, the lower 5 bits of FIG. 11 are represented using left and right meandering pits. That is, as shown in FIG. 13, the prepit is shifted by Δ1 from the position where the prepit should be (shown by a dotted line). Also, the other pre-pit is shifted from the original position by Δ2. More specifically, as shown in FIG. 14, the free area is increased by another bit, and the position of the pre-pit is shifted by １ ／ bit so that each phase corresponds to the lower bit.

In this case, Δ1 and Δ2 have the same value and are shifted in the same time axis direction.

In another embodiment, as shown in FIG. 14 (b), the lower bits are represented at the shift positions of the pair pits.

The lower bits may be divided into two by Δ1 and Δ2 to represent each bit. By doing so, the overhead of the empty area is reduced, and the data use efficiency is improved.

In the embodiment shown in FIG. 13, since a clock cannot be generated from pre-pits, a PLL is used in the SYNC area.
9 and the mark for PLL synchronization is shown in FIG.
(B) is formed as a continuous row of circular holes in the radial direction, and phase synchronization is achieved.

In this way, the currency track address can be accurately detected only by passing through the pre-pits.

As described above, a 14-bit encoding used as an access pattern uses an alternating binary code (gray code). In this case, since the sign change is only one bit, an error check or the like can be performed.

[0050]

According to the present invention, a tracking signal and clock information can be detected with high reliability from prepits meandering to the right and left even on an overwritable optical disk.
In addition, light spot phase information for access can be detected. In addition to the write-once disc, compatibility with other media can be ensured between devices and between media.
That is, a signal from a pre-pit is received by a single photodetector, and a new optical disc which does not cause a track shift due to disc tilt and movement of a light spot and which is not affected by a time shift of recording data due to thermal recording. Implement the device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of an optical disk device according to the present invention.

FIG. 2 is a diagram showing a track format.

FIG. 3 is a diagram showing detection signals from pre-pits and pits.

FIG. 4 is a diagram showing a disc format and a reproduction signal.

FIG. 5 is a diagram illustrating a recording timing shift.

FIG. 6 is a diagram showing an example of a track format according to the present invention.

FIG. 7 is a block diagram of a detection system.

FIG. 8 is a time chart for detecting a track shift.

FIG. 9 is a diagram showing an example of a SYNC.

FIG. 10 is a diagram showing an example of generation of a reproduction clock.

FIG. 11 is a diagram showing an example of a SYNC zone pattern for access.

FIG. 12 is a diagram showing an example of a SYNC zone pattern for access.

FIG. 13 is a diagram showing an example of a SYNC zone pattern for access.

FIG. 14 is a view showing a specific example of the pattern in FIG. 13;

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 20/10 301 G11B 20/10 301Z

Claims (23)

[Claims] 1. An optical disk having a plurality of sectors and a pair of marks slightly displaced left and right with respect to the track center in each of the plurality of sectors, wherein one and the other of the pair of marks are provided. An optical disk having a pattern indicating positional information for access between the optical disk and the optical disk. 2. The optical disk according to claim 1, wherein each of the sectors has an ID section and a data section, and the pair of marks are provided in the ID section. 3. The optical disk according to claim 1, wherein said pattern indicates address information. 4. The optical disk according to claim 1, wherein said pattern indicates a track address. 5. The optical disk according to claim 1, wherein at least a part of said pattern is provided between tracks. 6. The optical disk according to claim 1, wherein at least a part of the pattern is meandering right and left with respect to a track center. 7. The optical disk according to claim 6, wherein a mark position of a part of the meandering pattern is shifted by a predetermined amount from a fixed periodic position. 8. An optical disc having a track composed of a plurality of sectors and having a pair of marks slightly displaced left and right with respect to the track center in each sector of the plurality of sectors, each of the sectors includes an ID portion and a data. Part, the pair of marks is provided in the ID part, has a pattern indicating address information for access between one and the other of the pair of marks, at least a part of the pattern An optical disc provided between tracks. 9. The optical disk according to claim 8, wherein said pattern indicates a track address. 10. The optical disk according to claim 8, wherein at least a part of the pattern is meandering right and left with respect to a track center. 11. The optical disk according to claim 10, wherein a mark position of a part of the meandering pattern is shifted by a predetermined amount from a fixed periodic position. 12. A track comprising a plurality of sectors, wherein each of the plurality of sectors has a pattern indicating position information for access, which is partially provided between the tracks. optical disk. 13. The optical disk according to claim 12, wherein each of said plurality of sectors has a pair of marks slightly displaced left and right with respect to a track center. 14. The optical disk according to claim 13, wherein each of the sectors has an ID section and a data section, and the pair of marks are provided in the ID section. 15. The optical disk according to claim 13, wherein said pattern indicates address information. 16. The optical disk according to claim 12, wherein said pattern indicates a track address. 17. The optical disk according to claim 12, wherein at least a part of the pattern is meandering left and right with respect to a track center. 18. The optical disk according to claim 17, wherein a mark position of a part of the meandering pattern is shifted by a predetermined amount from a fixed periodic position. 19. A track comprising a plurality of sectors is provided, and at least a part of each of the plurality of sectors has a pattern indicating address information for access meandering right and left with respect to the track center. An optical disc characterized in that at least a part of the pattern is provided between tracks. 20. An optical disk according to claim 19, comprising a pair of marks slightly displaced left and right with respect to a track center, each of said sectors having an ID part and a data part, and said pair of marks comprising: An optical disc provided in the ID section and having the pattern between one and the other of the pair of marks. 21. The optical disk according to claim 19, wherein said pattern indicates a track address. 22. The optical disk according to claim 19, wherein a mark position of a part of the meandering pattern is shifted by a predetermined amount from a fixed periodic position. 23. A track comprising a plurality of sectors is provided, and at least a part of each of the plurality of sectors has a pattern indicating position information for access meandering right and left with respect to the track center. An optical disc characterized by the above-mentioned.