JPH08106644A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE: To increase recording capacity per one sheet of recording medium by making a servo standard clock frequency constant, and making a data standard clock frequency of an outer peripheral part of a recording medium higher than that of an inner peripheral part. CONSTITUTION: A second stage PLL circuit inputs a signal of a frequency to which a servo standard clock signal is frequency-divided by 1/8 frequency divider 15, and generates data standard clock. This PLL circuit is constituted with a phase comparator 16, a loop filter 17, a VCO 18, and a frequency divider 19 in which a frequency dividing ratio is variable. The frequency dividing ratio N of the frequency divider 19 is different depending on a zone in which information is recorded and/or reproduced, and controlled by a controller 14 so as to be N=14 in a zone A, N=13 in a zone B, N=12 in a zone C.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a concentric or spiral track, a sector for dividing the track into a plurality of tracks, and a predetermined number of discretely arranged tracking errors on each track. A servo area for detection, the track is divided into a plurality of areas in the radial direction, and the area on the outer peripheral side has a larger number of sectors per track than the area on the inner peripheral side. The present invention relates to an information recording / reproducing device using an information recording carrier.

[0002]

2. Description of the Related Art An optical disk device is generally used as a device for recording and / or reproducing information on a disk information record carrier. In such a device, the information string spacing is 1.5.
Since it is as narrow as μm to 1.6 μm, tracking servo is performed in order to align the light spot with the information string, and the deviation from the information string is detected by the optical means to displace the objective lens, which is the light collecting means. It is usually done. As a method for detecting this deviation, there is a discrete time method. This is as described in detail in Japanese Patent Laid-Open No. 59-3728, and as shown in FIG.
The front wobble pits 2 and the rear wobble pits 4 are arranged with a deviation of about 1/4 track pitch to the left and right of the above, and the deviation from the virtual track is detected from the optical modulation by them. More specifically, when the optical disc is rotated at a constant angular velocity and the light spot crosses the wobble pit, the locus A is deviated to the outer peripheral side of the disc, the virtual track 1, and the inner peripheral side of the disc as shown in FIG. The optical modulations detected when passing the deviated loci B are as shown in FIGS. 8e, f, and g. That is, when the light spot passes the locus A, it is close to the front wobble pit 2 and far from the rear wobble pit 4, so that the optical modulation by the front wobble pit 2 is large and the modulation by the rear wobble pit 4 is small. The opposite is true when the light spot passes the locus B. When passing through the virtual track 1, the front wobble pit 2,
The optical modulation by the rear wobble pit 4 becomes equal.

In the above method, the clock pit 3 is
It is used to generate a reference clock for extracting the tracking error signal. In the wobble pit string including the front wobble pit 2, the clock pit 3, and the rear wobble pit 4, when the optical disc is rotated at a constant angular velocity, a light spot periodically passes through the wobble pit. A signal indicating the peak time of the modulation signal by the clock pit 3 at that time is generated, and the reference clock of FIG. 8h is generated by the PLL (phase locked loop) circuit. The front wobble pits 2 and the rear wobble pits 4 are arranged so that the modulated signals appear at a time that is an integral multiple of the reference clock period when the optical disc is opened at a constant angular velocity.

The tracking error signal is the time t in FIG.
At 1 (that is, the rising edge of the reference clock signal), the modulation signal by the front wobble pit 2 is sampled and held, then at time t2, the modulation signal by the rear wobble pit 3 is sampled and held, and the latter is subtracted from the former of these two hold signals. It is obtained by doing. That is, when passing through the virtual track, the modulation signals of both wobble pits are equal, so the subtraction result is 0, and when passing through the locus A, the modulation signal of 2 in the front wobble pit is large and the modulation signal of the rear wobble pit 4 is large. Is small, the subtraction result is positive, and when passing through the locus B, the modulation signal of the front wobble pit 2 is small and the modulation signal of the rear wobble pit 4 is large, so the subtraction result is negative. Since such a tracking error signal is generated from the wobble pit string at almost constant intervals, it becomes a discrete time detection.
The modulation signal by the wobble pit train is generally repeated at a constant cycle over the entire surface of the optical disc. This effect is good at the seek time. When the optical spot is moved in the radial direction of the optical disk and tracking servo is applied to a desired track, if the appearance of the modulation signal by the wobble pit sequence is not periodic before and after the movement, a tracking error signal is extracted. In order to generate a reference clock for that, the pull-in operation of the PLL circuit is required again, and it is difficult to perform a quick tracking servo capture operation.

In such an information recording / reproducing apparatus which detects the tracking error signal in discrete time, the tracking error signal is extracted in the reference clock of the digital information recorded between the two wobble pit rows. It is possible to use the reference clock of.
That is, the light quantity of the semiconductor laser is modulated in synchronization with the reference clock signal of FIG. Draw marks and record digital information. Similarly in reproduction, the signal obtained by photoelectrically converting the reflected light from the optical disk is inspected at the time synchronized with the reference clock in FIG. 8h, and the presence or absence of the mark is determined to reproduce the digital information.

[0006]

However, when the reference clock for detecting the tracking error signal and the reference clock for recording and / or reproduction are made equal to each other, the optical disc is rotated at a constant angular velocity. ,
There is a problem that the utilization efficiency of the optical disk surface area is reduced. An important limitation for recording and reproducing is the size of the light spot. A typical optical disk device has a wavelength of about 8
When a 30 nm semiconductor laser and an objective lens with an NA of about 0.53 are used, the full width at half maximum of the light spot is about 1.5.
μm. In addition, the minimum inter-mark distance for safely performing recording and reproduction using such an optical spot is about 1.
5 μm. In an optical disc that rotates at a constant angular velocity, the linear velocity at the inner circumference is low, and the linear velocity becomes faster at the outer circumference.
Therefore, if the optical disc rotation speed and the reference clock are set so that the minimum inter-mark distance is 1.5 μm on the innermost track of the recording area, the minimum inter-mark distance on the outer periphery is 1.
Since it exceeds 5 μm, the surface area of the disk is wasted because of the light emission.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, to enable quick servo operation at the time of seek, and to increase the recording capacity per information recording carrier. Moreover, it is an object of the present invention to provide an information recording / reproducing apparatus capable of always accurately defining a data start point in each block and enabling stable recording and reproduction of information.

The above object is to detect a tracking error in which concentric or spiral tracks, sectors for dividing the tracks into a plurality of tracks, and a fixed number of discretely arranged tracks on each track. A plurality of wobble pits for, and a servo area including a clock pit for generating a servo and data reference clock signal, the track is divided into a plurality of areas in the radial direction,
The disc on the outer peripheral side has more sectors per track than on the inner peripheral side. The disc is rotated at a constant rotation speed, and the tracking error signal is detected based on a constant servo reference clock. In an information recording / reproducing apparatus that records and / or reproduces information by using a data reference clock that increases from the area on the inner peripheral side to the area on the outer peripheral side, the data reference clock is reset for each sector. It is achieved by being done.

[0009]

FIG. 2 is a schematic diagram showing an embodiment of an information recording / reproducing apparatus according to the present invention. Reference numeral 9 is an optical disc having a diameter of 86 mm which is an information recording carrier. The recording and reproduction of a magneto-optical signal is performed with a diameter of the magneto-optical disk 9 of 48 m.
It is carried out in the region from m 2 to 80 mm 2. 10 is a magneto-optical disk of 3600 r. p. This is a motor for driving at m, and its rotation speed is controlled by a rotation controller (not shown). Reference numeral 11 is an optical head, which is a semiconductor laser having a wavelength of 830 nm, which is a light emitting source, a collimator lens, an objective lens, and an actuator for driving the same in a focus direction and a squeezing direction, a polarization beam splitter, and photoelectric conversion Focusing servo of the light emitted from the semiconductor laser on the magneto-optical disk 9 including a pin photodiode, which is a container, is maintained at about 1.5 μm in full width at half maximum with the focus servo. Further, the reflected light from the optical disk 9 enters the pin photodiode through the polarization beam splitter, so that the optical modulation by the embossed pits of the optical disk 9 and the modulation by the Kerr effect by the magnetic mark are both performed by the same pin photodiode. It is photoelectrically converted and output to the signal processor 13. Reference numeral 12 is a linear motor for moving the optical head 11 to the semi-vacuum term of the magneto-optical disk 9. Reference numeral 14 is a controller for controlling the tracking actuator and the linear motor 12 in the optical head 11 based on the tracking error signal and the address information sent from the signal processor 13.

Next, the format of the magneto-optical disk 9 will be described. A recording / reproducing area extends from a radius of 40 mm to a half station of 24 mm, and 1672 servo bytes, which will be described later, are spirally arranged in a circle at a radial interval of 1.5 μm. Therefore, there are 10666 spiral virtual tracks with a pitch of 1.5 μm in the recording / reproducing area. The recording / reproducing area is divided into seven doughnut-shaped zones A to G as shown in FIG. Also, the digital information is recorded and reproduced in 512-byte units, and ECC (error correction code) and control data are added to the 512-byte data to obtain 584
The bytes are the actual recorded data. Further, this recording data is coded by 4/11 conversion and then recorded by NRZ (non-return to zero) modulation. That is,
There is a logical value 1 of the bit after encoding, and a logical value of 0
Corresponds to no mark. Here, the 4/11 conversion converts 8 bits of data into an 11 bit code as is well known, but since it is not directly related to the present invention, it will not be described in detail.

The actual recording data of 584 bytes is recorded / recorded in each sector, which is a recording unit in the magneto-optical disk.
Playback is performed. FIG. 4 is a diagram showing the contents of the sector. A sector is made up of n blocks, and the value of n varies depending on the zone shown in FIG. That is, n = 4 in the outermost zone A
5, n = 48 in zone B, n = 52 in zone C, n = 57 in zone D, n = 62 in zone E, zone F
Is n = 68, and in the innermost zone G is n = 76. In any of the zones, the first one block, that is, the block number # 0 is a non-recordable area, and a mark (sector mark) for identifying the beginning of a sector, a track address and a sector address are formed by embossed pits. . Subsequent block numbers # 1 and # 2 can be recorded, and logical sector addresses are recorded in these blocks. The recording / reproducing bit rate of these addresses is equal to the servo channel bit rate described later. Block numbers # 0 to #
There is a servo byte at the beginning of each block of (n-1),
It is divided into 22 servo channel bits. The rate of this servo channel bit is the same regardless of the zone, and is 60 (Hz) * 1672 (block /
Lap) * 100 (servo channel bit / block) ≒
It is 11.04 Mbps. Block numbers # 3 to # (n
-1) block is followed by a servo byte, and
Although 84 bytes of actual recording data is recorded, the number of actual recording data bytes per block differs depending on the zone. That is, m = 14 in zone A, m = 13 in zone B, m = 12 in zone C, m = 11 in zone D, zone E
, M = 10 in zone F, m = 9 in zone F, m = in zone G
8 The data channel bit rate of the data area in this block differs depending on the zone, and their ratio is equal to the ratio of the number of actually recorded data bytes in the block. That is,
Zone A: 11.04 * 14/8 ≈ 19.31 Mbps, Zone B: 11.04 * 13/8 ≈ 17.93 Mbps, Zone C: 11.04 * 12/8 ≈ 16.55 Mbps, Zone D: , 11.04 * 11 / 8≈15.17 Mbps, in zone E 11.04 * 10 / 8≈13.79 Mbps, in zone F 11.04 * 9 / 8≈12.41 Mbps, in zone G 11 .04 * 8/8 = 11.04 Mbps.

At the 3rd to 8th bits of the servo byte, a relative address is coded as an access mark to form an embossed pit. This is a pattern that repeats at a cycle of 18 tracks, and the seek operation is speeded up by detecting the position up to the target track while the optical head 11 is being moved by the linear motor 12 during seek.

From the 11th bit to the 17th bit, FIG.
As shown at the bottom of FIG. 1, the front wobble pit 2 and the rear wobble pit 4 for detecting the tracking error signal are biased with respect to the virtual track 1, and the clock pit 3 for generating the servo reference clock signal is the virtual track. It is formed as an embossed pit in the center of 1.

The signal processor 13 shown in FIG. 2 includes a two-stage PLL circuit as shown in FIG. In FIG. 1, the first-stage PLL circuit generates a servo reference clock signal from a clock pit signal generated when a light spot passes through a clock pit. The phase comparator 5, the loop filter 6, It comprises a voltage control oscillator (VCO) 7 and a 1/110 frequency divider 8. Two
The PLL circuit of the first stage receives the servo reference clock signal generated by the PLL circuit of the first stage and is divided by a 1/8 frequency divider 15, and generates a data reference clock. This PLL circuit includes a phase comparator 16, a loop filter 17, a VCO 18, and a frequency divider 19 with a variable frequency division ratio. The frequency division ratio N in the frequency divider 19 differs depending on the zone in which information is recorded and / or reproduced. In zone A, N = 14, in zone B, N = 13, in zone C, N = 12, and in zone D, N = 11, in zone E N = 10, in zone F N = 9, in zone G
It is controlled by the controller 14 so that N = 8. As is apparent from FIG. 1, the relationship between the frequency f1 of the clock pit signal and the frequency f2 of the servo reference clock is f2 = 110 · f1, and the frequency f3 of the data reference clock signal is f3 = N / 8 * F2 = N / 8 * 110 * f1. Here, the rotation speed of the optical disk 9 is 60 Hz,
Since there are 1672 clock pits per track, f1 = 100.32 KHz, f2≈11.04 MH
z.

Next, the operation will be described with reference to FIG.
FIG. 5 shows the waveform of each part when the light spot is passing through the sector of zone C. Symbol a is a signal photoelectrically converted by the photodetector of the optical head, and the modulation by the emboss mark and the magneto-optical mark appears as a modulation waveform with substantially the same amplitude. Reference numeral b is a clock pit signal, which is a pulse generated at the peak time of the clock pit of each servo byte. c is a servo reference clock generated by inputting the clock pit signal to the first-stage PLL circuit in FIG. 1, and d is a data reference clock similarly generated by the second-stage PLL circuit in FIG. However, in order to generate this data reference clock, after detecting the sector mark of the # 0 block, the 1/8 divider 15 of the PLL circuit of the second stage is reset by the clock pit signal of the # 1 block. This is because the frequency division is started once for each sector and the phase of the data reference clock is adjusted. From the # 0 block to the # 2 block, the mark is determined using the servo reference clock including the servo byte. After the # 3 block, the servo reference clock is used only for the servo bytes, and the data area is used for the mark determination using the data reference clock. In the wobble pits of all the servo bytes, a voltage value near the center is sampled and held by the servo reference clock, and then subtracted to generate a tracking error signal. Then, based on this, the controller 14 drives the tracking actuator in the optical head 11 to perform tracking servo, and the light spot follows the virtual track.

In the above embodiment, the servo byte is 2 bytes for the actual recording data, that is, 2 * 1 for the channel bit.
1 = 22 bits. Since the data reference clock is n / 8 times the servo reference clock, correction is necessary when the number of channel bits in the servo byte is not a multiple of 8. That is, in the above embodiment, 22/8 = 2.75, so the data reference clock in the servo byte is not an integer. For example, zone F
Then, the data reference clock is 9 / of the servo reference clock.
Since it is 8 times, the number of data reference clocks in the servo byte is 22 * 9/8 = 24.75. Therefore, when the data reference clock is used to determine the start time of the data area, it becomes 24 counts or 25 counts, which differs depending on the block. Since the count number of the day and area is constant at 99 counts per block in the zone F, the count number for assuming the block length is 24 + 99 = 123 or 25 + 99 = 12 for each block.
It is necessary to change it to 4.

The above embodiment shows a preferred example which does not require such correction. From the above description, it has been found that the reason why the correction is necessary is that the number of channel bits of the servo byte is not a multiple of the number of actual recording data bytes by the servo reference clock in the data area, that is, a multiple of 8. . Therefore, in this embodiment, the number of channel bits of the servo byte is set to 24 bits as shown in FIG. In addition, in the device configuration, the 1/110 frequency divider 8 in FIG.
Was changed to a 1/12 divider. By doing this,
Since the count number of the data reference clock in the servo byte is an integer, the data reference clock number in each block is also an integer. For example, in zone F, the number of data reference clocks in the servo byte is 27, the number of data reference clocks in the data area is 99, and the total block is 27 + 99.
= 126 pieces. Therefore, according to this embodiment, if the 1/8 frequency divider of the PLL is initialized once at the start of the sector and the starting point of the data area of the # 3 block is recognized,
After that, the next data area start point is exactly repeated every 126 counts of the data reference clock.

The present invention is not limited to the embodiments described above,
Various possibilities are possible. For example, the tracks may be formed in a concentric shape instead of a spiral shape. The present invention covers all such applications without departing from the scope of the claims.

[0019]

As described above, according to the present invention, the servo reference clock frequency is kept constant, and the data reference clock frequency is made higher in the outer peripheral portion than in the inner peripheral portion of the record carrier, so that the front surface of the record carrier is While maintaining the same tracking servo characteristics, the recording densities in the inner and outer peripheral portions of the record carrier can be made substantially equal, and the surface area of the record carrier can be effectively used to increase the recording capacity per record carrier. Is possible.

Further, since the data reference clock is reset for each sector, the data start point in each block can always be accurately determined, and stable recording and reproduction of information can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a PLL circuit of an information recording / reproducing apparatus based on the present invention.

FIG. 2 is a diagram showing an outline of an information recording / reproducing apparatus of the present invention.

FIG. 3 is a diagram showing zone division of an information record carrier used in the information recording / reproducing apparatus of the present invention.

FIG. 4 is a diagram showing a format of the record carrier shown in FIG.

5 is a diagram showing a signal waveform detected by the device shown in FIG.

FIG. 6 is a diagram showing another format of the third illustrated eternal record carrier.

FIG. 7 is a diagram showing a state of servo signals recorded on a record carrier.

FIG. 8 is a diagram illustrating a method of detecting a tracking error signal from a servo signal.

[Explanation of symbols]

 1 Virtual track 2 Front wobble pit 3 Clock pit 4 Rear wobble pit 5, 16 Phase comparator 6, 17 Loop filter 7, 18 Voltage control oscillator 8 1/110 frequency divider 15 1/8 frequency divider 19 Variable frequency division ratio Frequency divider

Claims (1)

[Claims] 1. A concentric or spiral track, a sector for dividing the track into a plurality of tracks, and a plurality of a plurality of tracks, which are discretely arranged on each track, for detecting a tracking error. It has a wobble pit and a servo area including a clock pit for generating a servo and a data reference clock signal, and the track is divided into a plurality of areas in the radial direction, and the track on the outer peripheral side of the inner peripheral side The area is rotated at a constant rotation speed in a disk shape with more sectors per track, and a tracking error signal is detected based on a constant servo reference clock.
In an information recording / reproducing apparatus that records and / or reproduces information using a data reference clock that rises from the inner peripheral side area toward the outer peripheral side area, the data reference clock is reset for each sector. An information recording / reproducing apparatus characterized in that