JPH01223634A - Optical information recording medium and recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute an access at high speed by providing intrinsic marks at an equal interval on a track, not varying a position of the first pit of a pair of pits and varying a position of the second pit in the track direction. CONSTITUTION:On a disk-like information recording medium 1, a track 2 is formed, and on the track, a sample mark 3 is provided periodically. The sample mark is constituted of two pits which are brought to wobbling in the opposite direction to each other against a virtual track center 2. The first pit 4 exists in a fixed position, and the second pit 5 changes its position little by little in accordance with the track. As for a pattern of the sample mark, there are six patterns in all, and it is repeated periodically at every six tracks. In such a way, since the number of sample marks becomes about three times per one round of the track, the sample period goes to about three times, a position delay by a sampler goes to about one third, and the stability increases further.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information recording medium and an apparatus for optically recording information, and particularly for recording and reproducing data based on information in pits provided in advance on a disk. The present invention relates to an optical information recording medium and a recording/reproducing apparatus suitable for recording.

[Prior Art] In recent years, so-called optical disk devices, which optically record and reproduce information on a disk-shaped recording medium, have been developed and are finally beginning to become popular. A format called a sampled format is known as one of the formats of such an optical disk system. This method is described in Proceedings of Niss B.I.E., Volume 695, Optical Mass Data Storage ■, 1986. Pages 112 to 115 and 2
Pages 39 to 242 (Proceeding o
f 5PIE, vol 695.0ptical M
ass Data St.

rage n, 1986. p112-p115. p
239-p242).

This format uses sample marks previously provided on the disc as shown in FIG.

Obtain tracking error signal and timing signal.

Multiply this timing signal to extract the clock signal,
Detection of servo system error signals such as tracking and focus, and data recording and reproduction are performed in synchronization with the extracted clock signal. Sample mark is at the virtual track center 6
-1.6-2, ..., a pair of wobbling pits 7-1.7-2, ..., 8-1.8-2 which are off-tracked in opposite directions by 1/4 track pitch ,
A tracking error signal is detected from the difference in amplitude of the reproduction signal between wobbling pits 7 and 8, which are composed of timing pits 9-1, 9-2, . Extract the clock from.

The area between pits 8 and 9 is a so-called unique pattern (18 consecutive 0's) that does not exist in the modulation pattern, and the sample mark is identified using this pattern. The position of the first wobbling pit 7 changes every 16 tracks. This is to obtain a cross-track signal during seek.

The data format is track 1 as shown in Figure 5.
The circumference is divided into 32 sectors, one sector is composed of 43 segments, and one segment is divided into 18 bytes. One byte is further divided into 15 channel bits. One of the segments is for sector identification information (ID), and the sector identification information (ID) is recorded by pre-pits. Data is recorded in the remaining 42 segments. One segment consists of a 2-byte sample mark and a 16-byte data area, so there are 6
72 bytes of data are recorded.

The 672 bytes of data includes 512 bytes of user data, 16 bytes of control data, and 1 error correction code.
It is 44 bytes.

During recording, data is converted from 8 bits per byte to 15 channel bits using a modulation method called 4/15 conversion, and is recorded in the data area between sample marks. The 4/15 conversion is detailed in the aforementioned literature. In 4/15 modulation, the 15th channel pit is always 0, and of the other 14 channel bits, two odd-numbered channel bits and two even-numbered channel pits are 1. A maximum of four consecutive 1's can occur, but if an O is inserted between 1's, at least two 0's are included. (During the data byte division, there may be only one O, but this is always 0, so it is not a problem.) When 0s are continuous, a maximum of 17 0s follow. (For example, data is 1
This is the case of OO1EE in hexadecimal notation, and the first data is 1
．． 2.5.6th and 2nd data 9.10.13.
The 14th channel pit becomes 1, and the others become O. ) At the time of reproduction, the reproduced signal amplitude for each channel pit is detected, and the top two reproduced signal amplitudes are selected for each odd-numbered and even-numbered pit, and it is determined that a pit, that is, 1, exists at that position. Then, data is obtained conversely from the 4/15 modulation conversion table.

The recording area of the disk is 60 mm in inner diameter and 120 mm in outer diameter, the track density is 1.5 μm/track, the linear recording density is 0.95 μm/pit, and the disk rotation speed is usually 18
The number of sample marks per round of the track is 1376, which is not specified, and the sampling frequency is about 41 kHz.

In this method, tracking servo is performed using only information from sample marks, so the amount of track movement at the time of access is also obtained from the sample marks.

As shown in FIG. 3, the position of the first wobbling pit 2 changes every 16 tracks, so by detecting the position of this pit, the amount of track movement every 16 tracks can be detected. The detection limit of the moving speed is about 1 m/s.

However, with this method, the amount of track movement during access is 1
There was a problem in that the resolution was low because it could only detect every 6 tracks. Furthermore, since this method uses only two patterns, there is also the problem that the direction of movement at the time of access cannot be determined.

[Problems to be Solved by the Invention] The above conventional technology has the problem that the movement direction at the time of access cannot be determined from the information of sample marks provided in advance on the disk, and the resolution of the track movement amount is low. There were also problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optimal format for an optical disk system in which the direction of movement at the time of access can be determined and the resolution of the amount of track movement is high.

[Means for Solving the Problem] The above object is to form a sample mark using only one pair of wobbling pits, to create at least three or more patterns by changing the position of one wobbling pit, and to form a sample mark using only one pair of wobbling pits. This is achieved by using patterns periodically as the track changes.

[Function] Generally, sample servo type optical disk devices use sample marks provided periodically on the disk to
Perform the following three actions.

(1) Extracting the clock used for recording and reproducing data.

(2) Detection of a tracking error signal for tracking the optical spot.

(3) Detection of track movement amount and movement direction for access.

In the present invention, a tracking error signal is detected from a playback signal of a wobbling pit by periodically providing sample marks consisting of only a pair of wobbling pits on a track, and the position of one of the wobbling pits is fixed. By extracting the clock from this pit and changing the position of the other pit, at least three types of sample marks are provided, thereby achieving improved resolution of the track movement amount and detection of the movement direction.

[Example] An embodiment of the present invention will be described below with reference to FIG. 1 and subsequent figures.

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows the pit arrangement of the embodiment of FIG.

Reference numeral 1 denotes a disc-shaped information recording can according to the present invention, on which a spiral or concentric track 2 is formed, and sample marks 3 are periodically provided on the track. As shown in FIG. 2, the sample mark is composed of two pits wobbled in opposite directions with respect to the virtual track center 2. 1st
The second pit 4 is located at a fixed position, and the second pit 5 changes its position little by little depending on the track. There are a total of six sample mark patterns, which are periodically repeated every six tracks.

FIG. 3 shows the data format of the embodiment shown in FIG.

One track consists of 22 sectors, and one sector is 1
It consists of 72 segments. One segment consists of a total of 5 bytes, including a 1-byte sample mark and a 4-byte data area.

The disc diameter is 48mm inside the user area.

The outer diameter is 80mm, and if the lead-in and lead-out areas are included, the inner diameter is 46mm and the outer diameter is 82mm.The rotation speed is 180mm.
In the case of Orpm, the linear recording density is 0°99 μm/pit (0.53 μm/channel pit), and 3784 sample marks per track circumference (sample period 113.
5kHz), and the user data is 581120M bytes.

Compared to the conventional example, the linear recording density is about 5% lower, and can be fully realized using exactly the same technology as the conventional example (laser wavelength 830 nm, lens aperture ratio 0.53). If the optical spot becomes smaller through optical improvements such as the laser wavelength and lens aperture ratio, it will be possible to utilize even the inner periphery, further increasing the user data capacity.

The user data transfer rate is 3.9 Mb in the conventional example.
ps, this is a decrease of 2.7 Mbps. However, this is due to a decrease in the disk diameter, and can be increased by increasing the disk rotation speed.

The sampling period is approximately three times that of the conventional model. This is due to the fact that the number of sample marks per track is about three times as large. Therefore, in feedback control systems such as track servo, focus servo, and clock regeneration PLL, the phase delay caused by the sampler is reduced to about one-third, and stability is further increased.

The resolution of track movement detection is one track. Also, the detection limit for the moving speed of trucks is approximately 0.85 m/cm, since up to 5 trucks can be detected in one sample period.
It becomes s. This is because the sample mark is made up of only a pair of wobbling pits, and one of the wobbling pits is also used as a timing pit, thereby halving the size of the sample mark and shortening the sample period without sacrificing redundancy. This is realized by That is, although there are only six patterns of sample marks, the detection limit of the moving speed of the track is high because the sample period is short. Since the recording area is 16 mm, assuming constant acceleration and deceleration, the average access time will be 12.5 ms, and sufficient performance can be achieved.

When the rotation speed is increased, for example, 2700-rp
If m, the recording density and the number of sample marks do not change,
The sampling period is 170.3 kHz, the user data transfer rate is 4.1 Mbps, and the detection limit of track moving speed is 1.28 m/s.

This corresponds to an average access time of 8.4 ms.

When the rotational speed increases, the characteristics required of the servo system are as follows.
If the conditions are exactly the same, the number of sample marks between tracks and circumferences may be the same in order to obtain the same servo characteristics. Disturbances in the servo system such as tracking and focusing are proportional to the square of the number of revolutions, but since the characteristics of the servo system are also quadratic, the required servo band is proportional to the number of revolutions. However, in reality, losses due to eddy currents occur in the lens actuator that forms the servo diameter, resulting in a phase lag in the high range, so when increasing the rotation speed, it is also necessary to increase the sampling period. However, as mentioned above, the number of sample marks has increased about three times compared to the conventional example, so there is no problem at all.

As described above, in the present invention, the sampling period is 3
The data density and redundancy are almost unchanged by 1, and the detection resolution of the track movement amount is 1 track, making it possible to detect the direction. The detection limit for track moving speed is also sufficient for access.

FIG. 6 shows an embodiment of an optical disk recording and reproducing apparatus using the disk of FIG. It is being A spindle motor 10 rotates the optical disc 1. Reference numeral 11 denotes an optical pickup, which focuses the laser beam irradiated from the laser 12 onto the recording surface 17 of the disk 1 through a collimating lens 13, a polarizing beam splitter 14, a quarter wavelength plate 15, and an objective lens 16. The light reflected from the recording surface 17 of the disk 1 travels in the opposite direction from when it was incident, is reflected by the polarizing beam splitter 14, and is focused onto the photodetector 19 by the detection lens 18. The photodetector 19 has two
The focus error signal is divided into two regions, and a focus error signal can be detected based on the difference in light amount between each region.

A differential amplifier circuit 20 amplifies the difference signal between the detection signals of the photodetector 19. A sample hold circuit 22 detects and holds a detected focus error signal (a value immediately after the first pit that is not affected by pits or data).

Reference numeral 23 denotes a servo circuit for performing focus servo, which moves an actuator 24 that drives the objective lens 16 in the focus direction to perform focus servo.

21 is an amplifier circuit, which detects the total amount of light incident on the photodetector 19. Reference numeral 25 denotes a peak detection circuit, which detects the peak position of the reproduced signal corresponding to the wobbling pit from the reproduced signal detected by the amplifier circuit 21. As shown in FIG. 7, the reproduction signal changes depending on the position of the second wobbling pit, and the output of the peak detection circuit 25 also changes. However, the position of the first wobbling pit does not change over the disk surface and always appears at a constant period even when no tracking servo is applied.

Therefore, the peak signal (64 in FIG. 7) corresponding to the first wobbling pit does not change, so the clock recovery circuit 26 uses the peak signal corresponding to the first wobbling pit to multiply the data by 75. Extract the clock for recording and reproducing. The period of the wobbling pit is 1
The clock frequency is 13.52 kHz (at 1800 rpm) and 8.514 MHz. The output of the clock regeneration circuit 26 is used as a clock for the digital processing circuit 27 except for the control circuit 34 which is composed of a microcomputer.

28 is a circuit that detects the amplitude of the reproduction signal of the wobbling pit and its position. For more information on this circuit,
This will be explained later. Reference numeral 29 denotes a tracking error signal detection circuit, which detects a tracking error signal from the difference in amplitude of the reproduction signal of the first and second wobbling pits. 33 is A
/D converter, and 31 is a track servo circuit.

The tracking error signal is output through the A/D converter 33 and drives the actuator 32 in the tracking direction to slightly move the objective lens 16 in the tracking direction to perform tracking.

Reference numeral 30 denotes a track movement amount detection circuit, which detects the track movement amount, track movement speed, and direction from the wobbling pit position signal output from the wobbling pit detection circuit 28. 34 is a control circuit composed of a microcomputer, which controls not only the entire drive device but also track access. The current position is calculated from the track movement amount output from the track movement amount detection circuit 30, and a target speed function is output. 35 is a subtraction circuit, and control circuit 3
4 outputs the speed target value and track movement amount detection circuit 30
The A/D converter 51 calculates the difference between the speed detection value outputted by the
Output through. 36 is a servo circuit for a linear motor for track access, which drives a linear motor 37 to move the entire optical pickup 11 in the track direction.

38 is a drive circuit for the semiconductor laser 12, and 39 is a data modulation circuit, which modulates the input recording data by 4715 and converts it into serial data. A thermal change is generated on the recording surface to form pits and record data. 4
0 is a difference detection circuit, which detects the pit position by comparing the amplitude of the reproduced signal. 41 is a demodulation circuit, 4/1
The recorded data is demodulated from the pit position signal according to the 5 modulation rule.

FIG. 8 shows details of the wobbling pit detection circuit 28, 42 is an A/D converter, 43 is a counter, 44.45.
46 and 47 are registers, 49 is a comparator, 48 is a comparator/selector, and 50 is a control section. The operation shown in FIG. 8 will be explained using FIG. 9. The wobbling pit detection circuit 28 is operated by a device comprising the clock recovery circuit 26 described above. Therefore, when wobbling pits are located at positions 3 and 10 of channel pits, the reproduced signal (A in FIGS. 8 and 9) takes maximum amplitude at positions 3 and 10 of channel pits. The A/D converter 42 detects the reproduced signal value at each clock point. The registers 44, 45, 46, and 47 are reset in advance, and the comparator/selector 48 compares the sizes of the registers 44 and 46, and selects the smaller one (the upper one is shown in FIG. 9).

) is output. A comparator 49 compares the output of the A/D converter 42 with the smaller one of the registers 44 and 46, and if the register is smaller, updates the value of the selected register and updates the value of the A/D converter 42. Incorporate. The control unit 50 outputs timing signals that control these operations. The counter 43 and registers 45 and 47 are for detecting the pit position, and the counter 43 is for detecting the pit position.
It is operated in synchronization with the channel pit as shown in the figure. Then, the value of the counter 43 is transferred to the register 45 using the same clock as the data is taken into the registers 44 and 46.
and is captured in the register 47.

The tracking error signal is obtained from the reproduction signal amplitudes of the two wobbling pits, that is, the values of registers 44 and 46 (B and D in FIG. 8). However, since it is not always clear which pit corresponds to which register, the determination is made using pit position signals (C and E in FIG. 8).

The amount and direction of movement of the track are determined from the pit position signals (C and E in FIG. 8). If the second pit position in the current sample mark is 10 and the previous value is 8, the difference (difference in mod 6 calculation) will result in the amount of track movement in one sample period being 2 tracks. It turns out that. The moving direction of the track can be similarly determined from the polarity of the difference in pit position signals. When the moving speed increases and exceeds half of the speed detection limit, both the amount and direction of truck movement become indistinguishable from truck movement in the opposite direction, but it is physically impossible for the moving speed to change suddenly. It can be identified from past moving speed values.

When the light spot passes between the tracks, crosstalk between the pits of the two tracks causes a three-dimensional difference in the playback signal.
Two peaks appear. Even in such a case, the pit position changes only in one place between tracks, so the 10th pit position changes.
Two peaks corresponding to the second pit 6 as shown in the figure
5.66, whichever is larger,
It will not be an incorrect value.

[Effects of the Invention] As described above, according to the present invention, almost the same technology as that for a 5.25-inch optical disc can be used for a 3.5-inch optical disc, and therefore, it is possible to use the same technology as for a 5.25-inch optical disc. Manufacturing technology and even optical pickups and signal processing methods can be shared. The data storage capacity is over 100 Mbytes, and the servo characteristics are improved and reliability is high. Furthermore, the track movement detection resolution is higher than that of a 5.25-inch optical disk, and the direction of movement can also be detected, allowing for faster access.

The sample mark used also consists of only two pits, making it easy to manufacture the disk.

[Brief explanation of the drawing]

1 and 2 are a plan view and a schematic diagram of an optical information recording medium according to an embodiment of the present invention, FIG. 3 is an explanatory diagram of a data format of an embodiment of the present invention, and FIG. 4 is a diagram used in a conventional example. 5 is an explanatory diagram of a conventional data format, FIG. 6 is a block diagram of an optical disk device according to an embodiment of the present invention, and FIG. 7 is a clock recovery circuit according to an embodiment of the present invention. FIG. 8 is a detailed block diagram of the embodiment of FIG. 6, and FIGS. 9 and 10 are diagrams of operation of the embodiment of FIG. 1...Disc, 2...Virtual track, 3...Sample mark, 4.5...Wobbling pit, 10...
... Spindle motor, 11... Optical pickup 12... Semiconductor laser, 28... Wobble pit detection circuit, 29...
...Tracking error signal detection circuit, 30...
- Track movement amount detection circuit.

Claims (6)

[Claims] (1) In a disk-shaped optical information recording medium, unique marks consisting of a pair of pits shifted in opposite directions with respect to the track center are provided on the track at equal intervals, and Accordingly, the first of the pit pair
An optical information recording medium characterized in that the position of the second pit does not change, but the position of the second pit changes in the track direction. (2) In the optical information recording medium according to claim 1, the optical information is characterized in that the positions of the second pits are present in at least three different positions and are periodically repeated according to changes in the track. recoding media. (3) The optical information recording medium according to claim 2, wherein the position of the second pit does not change over a plurality of tracks and repeats periodically according to changes in the track. Information recording medium. (4) The optical information recording medium according to claim 1, wherein the ratio of the length of the unique mark to the data area sandwiched between the marks is 1:4. . (5) The optical information recording medium according to claim 4, wherein the second pits are located at six different positions and are periodically repeated according to changes in the track. Medium. (6) Unique marks consisting of a pair of pits shifted in opposite directions with respect to the track center are provided on the track at equal intervals, and the first pit position of the pit pair is determined according to changes in the track. In a recording and reproducing apparatus using a disk-shaped optical information recording medium in which the position of the second pit changes in the track direction without changing, the recording and reproducing apparatus includes a peak detection circuit, a clock regeneration circuit, a wobbling pit detection circuit, and a tracking error detection circuit. circuit, and a track movement amount detection circuit, wherein the peak of the first pit is detected by the peak detection circuit, the clock is regenerated by the clock regeneration circuit, and the wobbling pit detection circuit detects the peak of the first pit and the track movement amount detection circuit. detect the reproduction amplitude value and pit position of the pit, the tracking error detection circuit detects a tracking error signal from the reproduction amplitude value of the pit, and the track movement amount detection circuit detects the amount of track movement from the pit position signal. A recording/reproducing device for an optical information recording medium, characterized in that: