JPH10144008A - Magneto-optical disk driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time before the frequency of a PLL part is stabilized by generating the readout reference clock of a reproduced signal after preliminarily applying a voltage becoming the recording frequency of an area to be accessed as the control voltage of a voltage controlled oscillator. SOLUTION: This magneto-optical disk driving device of a ZCAV(zone angular constant velocity) system is provided with a memory 11 in which digital data of control voltages becoming recording frequencies of areas to be accessed are stored as control voltages of a VCO 8 for generating the readout reference clock of the reproduced signal by being made to respectively correspond to plural areas, a D/A converter 12 for obtaining a control voltage from the digital data stored in the memory part 11 and a changeover switch 13 supplying an output to the VCO 8 while changing over the output of the D/A converter 12 and the output of a low-pass filter 10 and in this device, at the time of an access to a target area, the control voltage read out from the memory part 11 is supplied to the VCO 8 as a control voltage for free run.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention divides a disk into a plurality of areas from the inner circumference toward the outer circumference, and controls the spindle frequency so that the recording frequency is constant in one area. ZCAV (ZCV) that switches and controls the recording frequency to be higher in the outer peripheral area.
oned Annual Constant Ver
More particularly, the present invention relates to a magneto-optical disk drive device that reduces the time required for a PLL lock for generating a reference clock for reading a reproduction signal.

[0002]

2. Description of the Related Art Conventionally, magnetic recording and reproducing devices such as floppy disks and hard disk drives have been mainly supplied as devices for recording and reproducing various information.
-An optical disk device represented by a ROM is becoming widespread.

[0003] Among them, a magneto-optical disk drive device using a magnetic memory material is often used as a large-capacity external memory device of a computer or an image data memory due to its large capacity and disk compatibility. Has become.

A magneto-optical disk drive differs from a CD-ROM device originally developed for recording music.
To increase the search speed of the recorded information, a sector format method and CAV (Constant Angu) are used.
LAR VELOCITY) system.

FIG. 4 shows an outline of such a sector format type and CAV type disks.

[0006] In the figure, a portion indicated by reference numeral 51 (shaded portion) is a portion where address information (sector No. or track No.) is recorded, and a portion indicated by reference numeral 52 is a portion where data is recorded. . That is, the recording portion 51 of the address information is radially spread from the center of the disk from the inner peripheral side to the outer peripheral side of the disk recording area.

In such a system, the storage capacity per track is determined by the number of recordable marks at the innermost circumference of the disk recording area, and thus there is a problem that the storage capacity as a whole is reduced.

The ZCAV system takes advantage of the fact that the spindle motor of the CAV system is easily controlled, and divides the disk into a plurality of areas so that the recording frequency becomes higher toward the outer periphery.

FIG. 5 shows an outline of a ZCAV system disk.

In the figure, a portion indicated by reference numeral 41 (a hatched portion) is a portion where address information (sector No. or track No.) is recorded, and a portion indicated by reference numeral 42 is a portion where data is recorded. .

On the other hand, a CD in which the recording pit length is fixed (that is, the linear velocity is fixed) and the capacity is increased.
-CLV (Constant Line) like ROM
arVerocity) method. However, C
In the LV system, it is necessary to continuously and variably control the rotation speed of the spindle motor, which is disadvantageous for an information recording / reproducing apparatus in which access speed is important. Therefore, for an information recording / reproducing apparatus in which access speed is an important performance factor, it is better to keep the spindle motor rotation speed from the inner circumference to the outer circumference and not to spend time on the spindle motor rotation speed control. Is advantageously shortened.

Therefore, in a ZCAV type disc,
The disk is divided into a plurality of areas from the inner side to the outer side, and the spindle motor is controlled at a constant speed to keep the recording frequency constant in one area, thereby realizing a large capacity of the disk. ing. Therefore, the basic clock of the reproduction signal is required for the number of divided areas.

As a device for reproducing a signal recorded on such a disk, a disk reproducing device having a configuration shown in FIG. 6 has been conventionally used. This configuration is almost the same regardless of whether the disc adopts the CAV method or the disc adopts the ZCAV method.

In the figure, the output of the optical pickup 1 is
The output of the reproduction amplifier 2 and a reproduction signal from a reproduction signal device (not shown) are guided to a waveform equalizer 3. And
The output of the waveform equalizer 3 is guided to a decoder 6 via a shaper 4 and a discriminator 5. The output of the shaper 4 is PL
The output of the PLL circuit unit 7 is guided to the discriminator 5.

The PLL circuit unit 7 includes a voltage-controlled oscillator (Voltage) whose oscillation frequency is determined by a given voltage.
Controlled Oscillator (VCO)
8, a phase comparator 9 for comparing the phase of the frequency of the VCO 8 with the frequency of the reproduction signal and outputting an error voltage, and a low-pass filter (Low Pass Filter :) for removing unnecessary high frequency components of the output error voltage. LPF) 10.

When light emitted from a laser diode (not shown) is reflected on the disk, the optical pickup 1 detects rotation of the deflection surface caused by the Kerr effect depending on the direction of magnetization, and outputs information "0" and information "1". Is read based on the presence or absence of light output.

The waveform equalizer 3 corrects the signal waveform amplified by the reproduction amplifier 2 to reduce waveform interference.

The shaper 4 shapes the output of the waveform equalizer 3 and converts it into a pulse signal indicating the presence or absence of a signal.

The PLL circuit unit 7 is a circuit that creates a synchronization signal synchronized with the frequency of the fundamental cycle of the pulse signal converted by the shaper 4 and sends out the fundamental signal clock to the discriminator 5.

The discriminator 5 uses the synchronization signal from the PLL circuit unit 7 to determine whether or not there is a reproduction pulse signal within a predetermined time frame (detection window).

The decoder 6 demodulates the detection signal sequence obtained from the discriminator 5 into an original data bit sequence and outputs it.

Although not shown, the reproduction signal device includes a circuit for cutting unnecessary high frequency components and an automatic gain control device for stabilizing the output amplitude of the reproduction signal and ensuring the reproduction of the signal. (Automatic Gain Con
control: AGC).

[0023]

In the disk reproducing apparatus having such a configuration, when moving from one area to another area (hereinafter referred to as access), the apparatus always starts from a free-run frequency. Accessing a region having a high frequency requires a longer time until the frequency of the PLL circuit section is stabilized than accessing a region having a low frequency.

That is, the ZCAV disk device also needs to set the free-run frequency to the lowest frequency in order to realize compatibility with the past CAV disk. Even if the free-run frequency could be set to the highest frequency, the same would occur if the lowest frequency area was accessed.

For example, in the case of a 1.3 GB disc,
An area prepared as a VFO requires 3 to 4 bytes when fast and 7 to 8 bytes when slow, and there is twice the time difference. In addition, even when the speed is high, the difference between the free-run frequency and the frequency of the area to be accessed is several MHz, so that it is difficult to make the stability faster than this.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a control voltage of a voltage-controlled oscillator with a voltage which is a recording frequency of an area to be accessed beforehand, and then reproduce a reproduced signal. By generating the read reference clock, the time required for the frequency of the PLL circuit to stabilize can be reduced, and the frequency of the PLL circuit can be stabilized within the same time regardless of which area is accessed. An object of the present invention is to provide a magneto-optical disk drive.

[0027]

According to a first aspect of the present invention, there is provided a magneto-optical disk drive device which divides a disk into a plurality of areas from an inner peripheral side to an outer peripheral side, and comprises: While controlling the recording frequency to be constant in one area while keeping the rotation speed constant,
In a ZCAV type magneto-optical disk drive device that controls the recording frequency to be higher in the outer peripheral area,
PL for generating a reference clock for reading a reproduction signal
A memory unit for storing, as a control voltage of the voltage controlled oscillator in the L circuit unit, digital data of a control voltage corresponding to a recording frequency of an area to be accessed in association with each of the plurality of areas; A D / A converter for obtaining a control voltage from data; and a changeover switch for switching between the output of the D / A converter and the output of a low-pass filter in the PLL circuit section and supplying the output to the voltage controlled oscillator. When the area is accessed, the changeover switch is switched to the D / A converter side before the start of the PLL lock operation, and the digital data of the designated target area is read out from the memory unit, and the control voltage is controlled by the D / A converter. To the voltage-controlled oscillator via the changeover switch for free running. It is intended to supply.

According to this configuration, when an intended sector is to be accessed, the area to which the sector belongs is first calculated, and the D / A value of the control voltage calculated in advance for the area is stored in the memory unit. By assigning the control voltage to the VCO as a free-running voltage by designating the address, the lock settling time when the actual PLL circuit unit enters the lock operation can be shortened.

According to a second aspect of the present invention, there is provided a magneto-optical disk drive according to the first aspect, wherein the voltage controlled oscillator is controlled when the PLL circuit is in a lock operation state in an arbitrary area. An A / D converter for converting a voltage into digital data is compared with digital data obtained by the A / D converter and digital data in a corresponding area stored in the memory unit. And a data recording control unit for updating and recording the latest digital data obtained by the A / D converter as digital data in the area.

According to this configuration, even when the control voltage of the VCO when the PLL circuit locks is drifted due to a change in the ambient temperature or the like, the most recently accessed numerical value is stored in the memory. In addition, the lock operation of the PLL circuit unit can always be performed from the optimal free-run frequency.

According to a third aspect of the present invention, there is provided a magneto-optical disk drive according to the first or second aspect, wherein the control voltage is a recording frequency of each area previously recorded in the ROM in an initial design stage. And a means for loading the digital data into the memory unit.

According to this configuration, it is possible to prevent the operation from being disabled due to, for example, an instantaneous decrease in the power supply voltage or the incorporation of noise. In addition, when the method of digitizing the control voltage of the VCO and managing it on the memory unit is adopted, the method is effective even when reproducing a disc having a slight recording frequency difference because it is recorded by another drive device. It works.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the electrical configuration of a magneto-optical disk drive according to the present invention.

In the figure, 1 is an optical pickup, 2 is a reproduction amplifier, 3 is a waveform equalizer, 4 is a shaper, 5 is a discriminator, 6 is a decoder, 8 is a VCO, 9 is a phase comparator, Are LPFs, and their configurations are the same as those of the conventional disk reproducing apparatus shown in FIG.

According to the present invention, in addition to the above structure, the memory unit 1 stores digital data of a control voltage, which is a recording frequency of an area to be accessed, corresponding to each of a plurality of areas.
1, a D / A converter 12 for obtaining a control voltage from digital data stored in the memory unit 11, an output of the D / A converter 12, and an LP of the PLL circuit unit 17.
And a changeover switch 13 for switching between the output of F10 and supplying the output to the VCO 8.

In an arbitrary region, the PLL circuit unit 1
An A / D converter 14 for converting the control voltage of the VCO 8 into digital data when the lock 7 is in the lock operation state, and the digital data obtained by the A / D converter 14 and the corresponding area stored in the memory unit 11 And a data recording control unit 15 for updating and recording the latest digital data obtained by the A / D converter 14 as digital data in the area when the two data do not match.

That is, the output of the memory unit 11 is D / A
The D / A converter 12
Is connected to the terminal b of the changeover switch 13. The output of the LPF 10 is connected to the terminal a of the changeover switch 13 and to the A / D converter 14, and the output of the A / D converter 14 is guided to the data recording control unit 15. Further, the data recording control unit 15 is bidirectionally connected to the memory unit 11.

To the VCO 8, either the lock operation error voltage obtained through the LPF 10 or the free-run control voltage obtained from the memory unit 11 is supplied by switching the changeover switch 13. The switching operation of the changeover switch is controlled by system control means (not shown). The operation of reading digital data from the memory unit 11 and the operation of updating and recording the latest digital data are also controlled by the system control means.

FIG. 2 shows an outline of the format of a disk used by the magneto-optical disk drive device having the above configuration. This format is 130mm in diameter
It has a capacity of 1.3 gigabytes (GB) on both sides of the size, and an international standard has been established as ISO / IEC13549.

In this disk, the area is changed from "0" to "1".
5 ”, and B in order from the inner circumference side.
AND0, BAND1,..., BAND15. Therefore, the data to be stored in the memory is 16
Individual.

The frequency of the read clock (reference clock) of the innermost BAND0 is 21.9 MHz, and the frequency of the read clock of the outermost BAND16 is 42.5M.
Hz. That is, in the conventional method, the PLL
The lock time has a variation of about twice, most of which is due to the frequency difference between the read clocks being twice or more.

In FIG. 2, SM indicates the head of the sector format, and only this part needs to be read without using the clock reproduced by the PLL circuit unit 17.
For this reason, the mark length is particularly increased so that the signal output is larger than the other areas, or a unique data pattern is used so that the area can be clearly distinguished from other areas (address section, flag section, data section). .

The next VFO1 is a continuous repetitive data pattern (constant frequency portion) for reliably reproducing data even when the rotation of the disk fluctuates.
This is provided to lock the PLL circuit section 17 to this pattern (frequency) and generate a clock for reading data. This (VFO1) is always provided at the head of each address section, each flag section, and each data section. In the figure, VFO2 and VFO3 correspond to them.

In the next AM, a special code pattern indicating the start of address code data is set. Strong auto-correlation to reliably detect the data synchronization position,
The one that does not follow the modulation method of the data in the address part is selected. Here, the autocorrelation means a property that if the code pattern for comparison and the read code pattern are slightly shifted, the number of matching bits is extremely small.

In the next ID1, a track number, a sector number, and a CRC for error correction are written.
These are overwritten in order to ensure address detection, and ID2 and ID3 correspond to them.

The next PA is a postamble, which is used for absorption because the previous ID and CRC are of variable length recording.

The next ODF is a mark for offset detection in tracking servo error detection, which is simply a mirror surface.

The next GAP is a portion without data, FLAG
Is a part for writing a specified flag, ALPC is a blank part for controlling laser power, SYN
C is a portion where a pattern indicating the start of the user data portion is written. The last USER and DATA are parts that can be used by the user, and include an error correction code and the like.

Next, the operation of the magneto-optical disk drive of the present invention will be described using a disk having the above sector format.

Conventionally, the user has specified the physical track position and sector number of the disk, but the magneto-optical disk drive of the present invention simply specifies the serial number starting from 0. This unit is expressed as LBA (Log
ical Block Address).

For example, when accessing the address of the LBA 50, the address of the memory unit 11 in which the digital data of the control voltage of the innermost BAND0 is stored is designated, and the D / A
The data is output to the converter 12 and the switch 13 is switched to the terminal b (D / A converter 12) at the start of access. Therefore, at this time, the oscillation frequency of the VCO 8 is
The frequency is very close to the recording frequency of BAND0.

Thereafter, upon arrival at the VFO portion described above, the changeover switch 13 is switched to the terminal a side (LPF 10 side) to lock the PLL circuit section 17 to the clock of the reproduced signal.

As described above, according to the magneto-optical disk drive of the present invention, P
Since the lock frequency at which the LL circuit unit 17 should lock and the free-run frequency can be made close to each other, the PL
The time required for the L synchronization (capture operation) is shortened.

In a disk having the sector format shown in FIG. 2, a disk management area is often provided on the inner circumference side. Therefore, after reading the outermost circumference, the innermost circumference is accessed to update the disk management information. Even in the case where the operation is performed, in the conventional method, 42.5 MHz to 21.9 is used.
Although the PLL lock operation to MHz is performed, the present invention can always realize a short and stable PLL lock time even in the access between the BANDs in such a combination.

Similarly, when the outermost LBA is designated, the address of the memory unit 11 where the digital data of the control voltage of the BAND 15 is stored may be designated.
Thus, no matter what address is accessed, the PL
Since the voltage for L-synchronization can be made close to the free-run frequency, the time required for PLL synchronization is reduced, and a substantially constant lock time can be obtained even when such a movement between BANDs is performed. The design of the 17 timing control is simplified.

That is, if the constants of the phase comparator 9 and the LPF 10 are set so as to widen the capture range until the synchronization, the lock range becomes narrow due to the characteristics of the basic PLL circuit. Therefore, after PLL synchronization is obtained, it is necessary to reset the lock range to a constant that increases the lock range. At this time, if the PLL lock time is long, the switching timing has to be set immediately before the data part, so that the PLL lock range is narrow at the head of the data part, and PLL synchronization is disturbed. May become unreadable. On the other hand, in the magneto-optical disk drive of the present invention, since the PLL lock time is shorter than that of the conventional system, the changeover switch 13 can be switched in the middle of the VFO section further before the data section. In addition, there is an advantage that a data reading malfunction due to disturbance of the PLL lock is prevented.

When a system for obtaining a free-running control voltage from the memory unit 11 as in the present invention is adopted, if the voltage for actually locking the PLL is A / D converted and fetched as digital data, Higher accuracy PLL
Lock control becomes possible.

Therefore, in the present invention, the digital data fetched from the A / D converter 14 and the digital data stored in the memory unit 11 used for free running are compared in the data recording control unit 15, and both data are compared. If not, the latest digital data (ie,
Digital data captured from A / D converter 14)
Is updated and recorded in the memory unit 11 so as to remain. Since these are contents that can be easily realized by software, a detailed description of the algorithm will be omitted.

Regarding the handling of these digital data, digital data obtained by calculations and experiments at the time of the initial design is stored in the ROM, and transferred to the memory unit 11 when the power is turned on. The memory unit 11
A RAM or an EEPROM may be used. EEPROM
Then, there is no need to transfer the data from the ROM to the memory unit 11 when the power is turned on.

Further, as a countermeasure in the case where a malfunction occurs in the digital data of the memory unit 11 due to an instantaneous voltage drop or malfunction of the power supply, the digital data in the memory unit 11 is unconditionally assigned by assigning a special command. The software can also have the function of changing to the original data and the function of accessing the entire band of the disc to make the latest digital data.

FIG. 3 shows a block diagram of an embodiment for these configurations. In the embodiment, an access command is received by using SCSI for the interface with the host computer. Since these can exchange data with a common bus line 21, if the memory unit (memory device) 11 used in the present invention is naturally connected to the bus line 21, the above functions can be realized by software. it can.

[0063]

In the magneto-optical disk drive according to the first aspect of the present invention, the disk is divided into a plurality of areas from the inner circumference to the outer circumference, and the recording frequency is set in one area while the spindle speed is kept constant. In a ZCAV type magneto-optical disk drive device which controls the recording frequency to be higher toward the outer peripheral region while controlling the voltage to be constant, the voltage in the PLL circuit for generating the read reference clock of the reproduction signal is controlled. As a control voltage of the control oscillator, a memory unit for storing digital data of a control voltage which is a recording frequency of an area to be accessed in association with each of the plurality of areas, and a control voltage from the digital data stored in the memory unit D / A converter for obtaining the output, the output of the D / A converter, and the low-pass in the PLL circuit section. A switch for switching the output of the filter to supply the voltage-controlled oscillator to the voltage-controlled oscillator. When the target area is accessed, the switch is switched to the D / A converter side before the PLL lock operation is started, and the designated switch is switched. The digital data in the target area is read from the memory unit, converted into a control voltage by the D / A converter, and supplied to the voltage controlled oscillator via the changeover switch for free running. In other words, the lock frequency, which should be locked by the PLL circuit unit, and the free-run frequency can be made close to each other regardless of the address to be accessed, so that the time required for PLL synchronization (capture operation) can be shortened. , No matter which area you access, PL within the same time
The frequency of the L circuit can be stabilized. Also, P
It is necessary to switch the gain of the PLL circuit in order to widen the lock range once captured by the LL circuit. However, this switching control becomes easy, and there is sufficient margin when an actual reproduced signal is input. Since the gain can be set so as to extend the lock range by holding the signal, it is possible to reduce signal reading errors.

According to a second aspect of the present invention, there is provided a magneto-optical disk drive device according to the first aspect, wherein the control voltage of the voltage-controlled oscillator when the PLL circuit is in a lock operation state in an arbitrary region. An A / D converter for converting to digital data is compared with digital data obtained by the A / D converter and digital data in a corresponding area stored in a memory unit. A data recording control unit that updates and records the latest digital data obtained by the D converter as digital data in the area is provided. Is stored in the memory unit, so that the PLL can always be shifted from the optimal free-run frequency.
The locking operation of the circuit unit can be performed. In addition, since the frequency of the read clock can be constantly monitored, fine control is possible.

According to a third aspect of the present invention, there is provided a magneto-optical disk drive device according to the first or second aspect, wherein the control voltage is a recording frequency of each area previously recorded in the ROM in an initial design stage. The digital data stored in the memory unit is lost even when the digital data stored in the memory unit is lost due to, for example, an instantaneous drop in the power supply voltage or the incorporation of noise.
By loading the digital data recorded in M into the memory unit, it is possible to prevent inoperability,
The reliability can be dramatically improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a magneto-optical disk drive of the present invention.

FIG. 2 is a diagram showing an outline of a format of a disk used by the magneto-optical disk drive of the present invention.

FIG. 3 is a block diagram showing a means for loading digital data recorded in a ROM into a memory unit.

FIG. 4 is a schematic diagram of a CAV type disc.

FIG. 5 is a schematic view of a ZCAV type disc.

FIG. 6 is a block diagram showing an electrical configuration of a conventional signal recording / reproducing device.

[Explanation of symbols]

 Reference Signs List 8 voltage controlled oscillator (VCO) 9 phase comparator 10 low-pass filter (LPF) 11 memory unit 12 D / A converter 13 changeover switch 14 A / D converter 15 data recording control unit 17 PLL circuit unit

Claims (3)

[Claims] 1. A disk is divided into a plurality of areas from an inner peripheral side toward an outer peripheral side, and the number of spindles is kept constant at a constant value.
In a ZCAV type magneto-optical disk drive device in which the recording frequency is controlled to be constant in one region and the recording frequency is controlled to be higher in the outer peripheral region, a reference clock for generating a read signal of a reproduction signal is generated. PL
A memory unit that stores, as a control voltage of the voltage controlled oscillator in the L circuit unit, digital data of a control voltage that is a recording frequency of an area to be accessed, corresponding to each of the plurality of areas; A D / A converter for obtaining a control voltage from data, and a changeover switch for switching between an output of the D / A converter and an output of a low-pass filter in the PLL circuit unit and supplying the output to the voltage controlled oscillator. At the time of access to the area, the changeover switch is switched to the D / A converter side before the PLL lock operation is started, and digital data of the designated target area is read out from the memory unit, and the control voltage is controlled by the D / A converter. To the voltage-controlled oscillator via the changeover switch for free running. Magneto-optical disk drive apparatus and supplying. 2. An A / D converter for converting a control voltage of the voltage controlled oscillator into digital data when the PLL circuit section is in a lock operation state in an arbitrary region, and a digital signal obtained by the A / D converter. Comparing the data with the digital data of the corresponding area stored in the memory unit, and when the two data do not match,
2. A data recording control unit for updating and recording the latest digital data obtained by the A / D converter as digital data of the area.
The magneto-optical disk drive device according to claim 1. 3. The apparatus according to claim 1, further comprising means for loading digital data of a control voltage, which is a recording frequency of each area pre-recorded in a ROM in an initial design stage, into said memory unit. Magneto-optical disk drive device.