JP2002288902A - Magneto-optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical disk device in which a signal is exactly reproduced from a magneto-optical recording medium by irradiating the medium with a pulsed light. SOLUTION: In the magneto-optical disk device 100, an optical head 101 irradiates the magneto-optical recording medium 10 with the pulsed light in synchronization with a delay clock having a phase changed from that of a clock CLK. Then, an amplitude detecting circuit 108 detects the amplitude of a reproduced signal which is detected by using the pulsed light irradiated in synchronization with the delay clock having its phase changed, and outputs the detection result to a CPU 109. The CPU 109 decides the amount of delay of the delay clock or producing the pulsed light so that the amplitude of the reproduced signal is maximized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk drive for reproducing signals from a magneto-optical recording medium using pulsed light.

[0002]

2. Description of the Related Art Magneto-optical recording media have attracted attention as rewritable, large-capacity, and highly reliable recording media, and have begun to be put to practical use as computer memories and the like. Recently, the recording capacity has been increased to 6.0 Gbyte.
es magneto-optical recording medium is AS-MO (Advanced)
Storage Magneto Opticald
isk) It is standardized as a standard and is about to be put to practical use.

When recording a signal on such a magneto-optical recording medium, a magnetic head is brought into contact with the surface of the magneto-optical recording medium on which the magnetic layer is formed, and the magneto-optical recording medium is rotated at a predetermined rotation speed. A magnetic field modulated by a recording signal is applied to the magnetic layer of the magneto-optical recording medium while the magnetic head is floated. Then, a laser beam is irradiated from the side opposite to the magnetic head to heat a predetermined region of the magnetic layer of the magneto-optical recording medium to a certain temperature or higher. Thereby, a magnetic domain having a different magnetization direction is formed in the recording layer of the magnetic layer based on the recording signal, and the signal is recorded.

When a signal is reproduced from a magneto-optical recording medium, a laser beam is applied to transfer a magnetic domain in a region heated to a predetermined temperature or higher to a reproducing layer. It is detected as the rotation angle of the polarization plane of light. Thus, a signal is reproduced from the magneto-optical recording medium.

Further, recently, a signal is reproduced from a magneto-optical recording medium by irradiating a pulse light. In this case, a clock synchronized with the fine clock mark detected from the magneto-optical recording medium is generated, and pulse light is emitted based on the generated clock. And
In synchronization with a delayed clock whose clock phase is delayed by a certain amount, a magneto-optical signal detected by pulse light is converted from an analog signal to a digital signal to detect a reproduced signal.

[0006]

However, when reproducing a signal from a magneto-optical recording medium using pulsed light, if the irradiation timing of the pulsed light is shifted, a processing circuit for processing the magneto-optical signal detected by the optical head into reproduced data. However, there is a problem that a reproduced signal having a large amplitude cannot be obtained. That is, there is a problem that signals cannot be accurately reproduced from the magneto-optical recording medium.

Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a magneto-optical disk drive capable of accurately reproducing a signal from a magneto-optical recording medium by irradiating pulse light. That is.

[0008]

According to the present invention, a magneto-optical disk device is a magneto-optical disk device for reproducing a signal from a magneto-optical recording medium using a laser beam, and is formed on the magneto-optical recording medium. A clock generation circuit that detects the fine clock mark and generates a clock, a delay circuit that generates a delay clock and a fixed clock by delaying the clock generated by the clock generation circuit, and a pulse light synchronized with the delay clock. Irradiating the magneto-optical recording medium,
An optical head for detecting a magneto-optical signal from a magneto-optical recording medium, an amplitude detection circuit for detecting the amplitude of the magneto-optical signal detected by the optical head in synchronization with a fixed clock, and when a delay amount of a delayed clock is changed And a delay amount determining circuit for determining the delay amount of the delay clock at which the received amplitude has the maximum value, and setting the determined delay amount in the delay circuit.

Preferably, the amplitude detection circuit converts the magneto-optical signal from the optical head from an analog signal to a digital signal in synchronization with a fixed clock and outputs a reproduced signal.
A converter, a peak detection circuit for detecting a peak value of the reproduced signal at each timing of the fixed clock, and a plurality of peak values detected by the peak detection circuit, and an average value of the received plurality of peak values is calculated. And an averaging circuit that outputs an amplitude.

Preferably, the amplitude detection circuit converts the magneto-optical signal from the optical head from an analog signal to a digital signal in synchronization with a fixed clock and outputs a reproduced signal.
A converter, a peak detection circuit for detecting a peak value of the reproduced signal at each timing of the fixed clock, and a plurality of peak values detected by the peak detection circuit, and an average value of the received plurality of peak values is calculated. A first averaging circuit that outputs an average peak value, a bottom detection circuit that detects a bottom value of the reproduction signal at each timing of the fixed clock, and a plurality of bottom values detected by the bottom detection circuit. A second averaging circuit that calculates an average value of the plurality of bottom values and outputs an average bottom value, and a difference circuit that calculates a difference between the average peak value and the average bottom value and outputs an amplitude.

Further, according to the present invention, a magneto-optical disk drive is a magneto-optical disk drive for reproducing a signal from a magneto-optical recording medium using a laser beam, wherein a fine clock mark formed on the magneto-optical recording medium is provided. A clock generation circuit that detects the clock and generates a clock; a delay circuit that generates a delay clock and a fixed clock by delaying the clock generated by the clock generation circuit; and a magneto-optical recording medium that outputs pulse light synchronized with the delay clock. An optical head for detecting a magneto-optical signal from a magneto-optical recording medium, an error detection circuit for detecting the number of errors of the magneto-optical signal detected by the optical head in synchronization with a fixed clock, and a delay amount of a delay clock Is received from the error detection circuit when the number of errors is changed, and the number of received errors is smaller than a predetermined number. Determining the delay amount of the extension clock, and a delay amount determining circuit for setting the amount of delay to the decision on the delay circuit.

Preferably, the magneto-optical signal detected by the optical head when the delay amount of the delay clock is changed is a signal of a predetermined pattern recorded on a magneto-optical recording medium.

[0013]

Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

Referring to FIG. 1, a description will be given of a magneto-optical recording medium 10 on which data is recorded and reproduced by a magneto-optical disk device 100 according to the present invention. In the magneto-optical recording medium 10, frames as recording units are arranged at regular intervals, and each frame is composed of 39 segments (Segments) S0, S1, S2,..., S38.

The magneto-optical recording medium 10 has a planar structure in which grooves 1 and lands 2 are alternately formed in the radial direction, and the grooves 1 and lands 2 are arranged spirally or concentrically. And the length of each segment is 532
DCB (Data Channel Bit)
At the beginning of each segment, a fine clock mark (FCM: Fine Clock Mark) 3 indicating phase information of a clock for recording and reproducing data is formed. The fine clock mark 3 is formed by providing lands of a fixed length at regular intervals on the groove 1 and providing grooves of a constant length at regular intervals on the lands 2. Then, the segment S, which is the head of the frame,
After the fine clock mark 3, the address information (Addr) indicating the address on the magneto-optical recording medium 10 is set to 0.
ess) is preformatted by the wobbles 4 to 9 when the magneto-optical recording medium 10 is manufactured.

Wobbles 4 and 5, wobble 6 and wobble 7, and wobble 8 and wobble 9 are formed on opposite walls of groove 1 and record the same address information. Such a method of recording address information is called a one-sided staggered method. By adopting the one-sided staggered method, a tilt or the like occurs in the magneto-optical recording medium 10, and even when the laser light is deviated from the center of the groove 1 or the land 2, the information is accurately recorded. Address information can be detected.

The area where the address information is recorded and the area where the fine clock mark 3 is formed are not used as areas for recording user data. Segment S
n is the fine clock mark 3 and the user data Use
r Data n-1.

Referring to FIG. 2, a detailed configuration of the segment will be described. Each segment S constituting the frame
0, S1, S2,..., S38, the segment S0 is an address segment preformatted on the magneto-optical recording medium 10, and the segments S1 to S
A data segment 38 is reserved as a recording area for user data. The segment S0 is composed of the fine clock mark area FCM of 12 DCB and the address Address of 520 DCB.
Is a 12DCB fine clock mark area FCM
, 4DCB Pre-Write, 512DCB Data, and 4DCB Post-Write.

Pre-Write indicates the writing of data, for example, a predetermined pattern "001".
The Post-Write indicates the end of the data. For example, the Post-Write indicates a predetermined pattern “1”.
100 ".

The user data area of the segment S1 is provided with a header (Header) which is a fixed pattern for performing data position confirmation during reproduction, position compensation of a reproduction clock, laser power adjustment, and the like. The fixed pattern to be recorded in the header is a pattern in which a DC component is suppressed. For example, a pattern in which a predetermined number of 2T domains are formed at intervals of 2T and a pattern in which a predetermined number of 8T domains are formed at intervals of 8T are recorded. You.

Then, phase compensation is performed by adjusting the sampling timing of an analog signal obtained by reproducing the 2T domain so as to match the phase of a clock used for data recording and reproduction, thereby performing phase compensation. The 8T domain is reproduced, and the laser power is adjusted so that the ratio of the 2T domain reproduced signal strength to the 8T domain reproduced signal strength becomes 50% or more. Also, by confirming whether or not the position of the digital signal obtained by reproducing the 8T domain and binarizing the reproduced signal matches the position of the digital signal of the 8T domain predicted in advance, the position of the data at the time of reproduction can be confirmed. Do. Further, each pattern of Pre-Write, Post-Write, and Header is recorded continuously with the user data when recording the user data.

Referring to FIG. 3, a magneto-optical disk drive 100 according to the present invention includes an optical head 101, a reproduction signal generation circuit 102, an FCM detection circuit 103, a clock generation circuit 104, a signal processing circuit 105, Servo circuit 1
06, the spindle motor 107, and the amplitude detection circuit 10
8, a CPU 109, a magnetic head drive circuit 110,
A laser drive circuit 111, an encoder 112, and a magnetic head 113 are provided.

The optical head 101 includes the magneto-optical recording medium 10
Is irradiated with pulsed light, and the reflected light is detected. The reproduction signal amplification circuit 102 amplifies the tracking error signal, the focus error signal, and the magneto-optical signal detected by the optical head 101 to a predetermined level, outputs the tracking error signal and the focus error signal to the servo circuit 106, The signal is output to the signal processing circuit 105 and the amplitude detection circuit 108. The FCM detection circuit 103 generates a fan clock mark detection signal based on the optical signal detected by the optical head 101 due to the fine clock mark formed on the magneto-optical recording medium 10, and generates the generated fine clock mark detection signal. Clock generation circuit 1
04 and the amplitude detection circuit 108.

The clock generation circuit 104 generates a clock based on the fine clock mark detection signal from the FCM detection circuit 103, and outputs the generated clock to the amplitude detection circuit 108 and the signal processing circuit 105. The signal processing circuit 105 converts the magneto-optical signal input from the reproduction signal generation circuit 102 from an analog signal to a digital signal in synchronization with the clock from the amplitude detection circuit 108,
High-frequency and low-frequency noises are cut, decoded, error-corrected, and reproduced data is output.

The servo circuit 106 is driven under the control of the CPU 109. Then, the servo circuit 106
Turns on the tracking server and the focus servo of the objective lens (not shown) in the optical head 101 based on the tracking error signal and the focus error signal input from the reproduction signal amplifier circuit 102. Further, the servo circuit 106 rotates the spindle motor 107 at a predetermined rotation speed. The spindle motor 107 is
The magneto-optical recording medium 10 is rotated at a predetermined rotation speed.

The amplitude detection circuit 108 detects the amplitude of the magneto-optical signal in synchronization with a fixed clock obtained by delaying the clock input from the clock generation circuit 104 and outputs the detected amplitude to the CPU by a method described later. I do. Further, the amplitude detection circuit 108 delays the clock based on the control from the CPU 109 and outputs the delayed clock to the laser drive circuit 111. Further, when the delay amount of the delay clock is input from the CPU 109, the amplitude detection circuit 108 delays the clock based on the delay amount, and outputs the delayed clock to the laser drive circuit 111. The CPU 109 controls each unit of the magneto-optical disk device 100, determines the amount of clock delay for maximizing the amplitude of the magneto-optical signal by a method described later, and uses the determined amount of delay as the amplitude detection circuit 10
8 is output.

The magnetic head drive circuit 110 controls the magnetic head 1 based on the recording signal input from the encoder 112.
13 is driven. The laser drive circuit 111 controls the optical head 10 based on the delayed clock from the amplitude detection circuit 108.
1 is driven. The encoder 112 encodes the recording data and outputs the encoded recording signal to the magnetic head drive circuit 110. The magnetic head 113 is driven by the magnetic head drive circuit 110 and applies a magnetic field modulated by a recording signal to the magneto-optical recording medium 10.

Referring to FIG. 4, address information AD from fine magnetic recording medium 10, fine clock mark FCM,
The detection of the magneto-optical signal RF will be described. Area 1
0A and the area 30A constitute a preformat area that is preformatted when the magneto-optical recording medium 10 is manufactured. In the area 10A, wobbles 4 to 7 and fine clock marks 3A and 3B are formed. In addition, the area 30A
Are formed with fine clock marks 3A and 3B.
The area 20A constitutes a user data area, in which user data is recorded.

The magneto-optical recording medium 10 is irradiated with a laser beam,
Photodetector 1 in optical head 101 for detecting the reflected light
020 indicates six detection areas 1020A, 1020B, 1
020C, 1020D, 1020E, and 1020F. The area A 1020A and the area B 1020B, and the area C 1020C and the area D 1020D
In the tangential direction DR1 of the region A10
20A and area D1020D, area B1020B and area C
1020C, and areas E1020E and F1020
F is arranged in the radial direction DR2 of the magneto-optical recording medium 10.

The area A 1020A, the area B 1020B, the area C 1020C, and the area D 1020D respectively correspond to the A of the laser beam LB applied to the magneto-optical recording medium 10.
The reflected light in the region, the B region, the C region, and the D region is detected. Further, a region E1020E and a region F1020
F indicates the laser light reflected by the laser light LB in the entire area A, area B, area C, and area D.
The laser beam diffracted in two directions having different polarization planes by the Wollaston prism (not shown) is detected.

The reproduction signal RF of the magneto-optical signal recorded in the user data area 20A is supplied to the photodetector 1020.
Is detected by calculating the difference between the laser light intensity [E] detected in the region E1020E and the laser light intensity [F] detected in the region F1020F. That is, the differentiator 400 of the circuit 40 calculates the difference between the laser light intensity [E] detected in the region E1020E and the laser light intensity [F] detected in the region F1020F, and obtains the reproduction signal RF =
[E]-[F] is output.

Area 10 constituting preformat area
Address information A recorded by wobbles 4 to 7 of A
The reproduction signal of D is detected by the radial push-pull method, and the laser detected in the area C1020C is obtained from the sum of the laser light intensity [A] detected in the area A1020A and the laser light intensity [B] detected in the area B1020B. It is detected as a value obtained by subtracting the sum of the light intensity [C] and the laser light intensity [D] detected in the area D1020D. That is, the address information AD is detected by the adders 500 and 501 and the subtractor 502 constituting the circuit 50.
The adder 500 outputs [A + B] obtained by adding the laser light intensity [A] detected in the region A 1020A and the laser light intensity [B] detected in the region B 1020B. The adder 501 outputs [C + D] obtained by adding the laser light intensity [C] detected in the region C1020C and the laser light intensity [D] detected in the region D1020D. Then, the subtractor 502 subtracts the output [C + D] of the adder 501 from the output [A + B] of the adder 500, and outputs a reproduced signal AD = [A + B] − [C + D] of the address information.

The fine clock marks 3A and 3B of the area 30A constituting the preformat area are detected by the tangential push-pull method, and the area A1 is detected.
Laser light intensity [A] detected at 020A and area D10
From the sum of the laser light intensity [D] detected at 20D and the laser light intensity [B] detected at region B1020B and the region C
It is detected as a value obtained by subtracting the sum with the laser light intensity [C] detected at 1020C. That is, the fine clock marks 3A and 3B are added to the adder 50 constituting the circuit 50.
3, 504 and a subtractor 505. The adder 503 outputs [A + D] obtained by adding the laser light intensity [A] detected in the area A1020A and the laser light intensity [D] detected in the area D1020D. Adder 50
4 outputs [B + C] obtained by adding the laser beam intensity [B] detected in the region B1020B and the laser beam intensity [C] detected in the region C1020C. Then, the subtractor 505 subtracts the output [B + C] of the adder 504 from the output [A + D] of the adder 503, and outputs a reproduced signal FCM = [A + D] − [B + C] of the fine clock mark.

Referring to FIG. 5, the configuration of clock generating circuit 104 included in magneto-optical disk device 100 shown in FIG. 3 will be described. The clock generation circuit 104 includes a phase comparison circuit 1041, an LPF 1042, and a voltage controlled oscillator (VC
O) 1043 and a 1/532 frequency divider 1044. The 1/532 frequency divider 1044 is connected to a voltage controlled oscillator (V
CO) 1043 is set to 1
The frequency is divided to / 532. The phase comparator 1041 calculates 1/53
The phase of the clock CK1 frequency-divided by the 2 frequency divider 1044 is compared with the phase of the fine clock mark detection signal FCMT, and an error voltage corresponding to the phase difference is generated. Therefore, this clock generation circuit 104 generates a reference clock CLK synchronized with the fine clock mark detection signal FCMT and having a period of 1/532 of the fine clock mark detection signal FCMT.

Referring to FIG. 6, detection of fine clock marks 3A and 3B and generation of reference clock CLK will be described. Light detection unit 1020 of optical head 101
As described with reference to FIG. 5, the fine clock marks 3A,
3B, and outputs the detected fine clock mark signal FCM to the FCM detection circuit 103. The FCM detection circuit 103 generates a fine clock mark detection signal F based on the input fine clock mark signal FCM.
Generate CMT. That is, in the FCM detection circuit 103, the fine clock mark signal FCM is compared at a predetermined level and converted into a signal FCMC. Then, the signal FCMC is inverted to the signal / FCMC. Thereafter, the rising edge is synchronized with the position of the point P where the polarity of the fine clock mark signal FCM is switched, and the detection window signal DEWIN having the amplitude width of 6 DCB is generated. The product is calculated to generate signal FCMP. Then, the fine clock mark detection signal FCM having an amplitude width of 1 DCB synchronized with the rise of the signal FCMP
Generate T.

The fine clock mark signal FCM shown in FIG.
The fine clock mark signal detected when traveling on the vehicle has been described. The fine clock mark signal detected when the laser beam travels on the land 2 only changes its polarity, and the position of the point P does not change. Therefore, when the laser beam travels on the land 2, the signal FCMP and the fine clock mark detection signal F
CMT can be generated.

The FCM detection circuit 103 outputs the detected fine clock mark detection signal FCMT to the clock generation circuit 104. The clock generation circuit 104 synchronizes with the fine clock mark detection signal FCMT as described with reference to FIG.
Generate LK.

Referring to FIG. 7, the amplitude detection circuit 108 of the magneto-optical disk device 100 shown in FIG.
81, a peak detection circuit 1082, and an averaging circuit 108
3, the timing generation circuit 1084, and the delay circuit 108
5 is included.

The AD converter 1081 includes a delay circuit 1085
In synchronization with the fixed clock CLKk from the CPU, the magneto-optical signal RF input from the reproduction signal amplifier circuit 102 is converted from an analog signal to a digital signal. Peak detection circuit 108
2 detects the peak value of the magneto-optical signal RFD input from the AD converter 1081 in synchronization with the fixed clock CLKk only during the period when the 8T detection signal DTS from the timing generation circuit 1084 is at the H (logic high) level, The plurality of detected peak values are output to the averaging circuit 1083. The averaging circuit 1083 calculates the average of the plurality of peak values input from the peak detection circuit 1082 during the period when the 8T detection signal DTS is at the H level, and outputs the calculated average value to the CPU 109 as the amplitude of the magneto-optical signal. .

The timing generation circuit 1084 detects the 8T signal recorded in the header area of the magneto-optical recording medium 10 based on the fine clock mark detection signal FCM input from the FCM detection circuit 103. A DTS is generated, and the generated 8T detection signal is output to the peak detection circuit 1082 and the averaging circuit 1083.

The delay circuit 1085 is a clock generation circuit 1
A fixed clock CLKk is generated by delaying the clock CLK from the fixed clock CLK by a fixed amount, and the generated fixed clock CLk is generated.
Kk is converted to an AD converter 1081 and a peak detection circuit 108
Output to 2. Further, the delay circuit 1085 generates the delayed clocks CLK1 to CLKn in which the phase of the clock CLK is delayed in the practice mode for optimizing the clock for generating the pulse light in which the amplitude of the magneto-optical signal is maximized. The delayed clocks CLK1 to CLKn are output to the laser drive circuit 111. Further, the delay circuit 10
When the optimum delay amount is input from the CPU 109, the 85 generates a delay clock CLKopt in which the phase of the clock CLK is delayed by the input delay amount, and outputs the delayed clock CLKopt to the laser drive circuit 111.

Referring to FIG. 8, peak detection circuit 1082
The detailed operation of the averaging circuit 1083 will be described. The peak detection circuit 1082 receives the fixed clock CLKk from the delay circuit 1085,
84, receives the 8T detection signal DTS, and further converts the magneto-optical signal R converted into a digital signal from the AD converter 1081.
Receive FD. Then, the peak detection circuit 1082
The magneto-optical signal RFD is synchronized with the fixed clock CLKk only during the periods T1 and T2 when the 8T detection signal DTS is at the H level.
The peak value of is detected. That is, the peak detection circuit 10
82 indicates a component S of the magneto-optical signal RFD during the period T1.
The peak value of S1 is detected in synchronization with the fixed clock CLKk to obtain the component P1 of the peak value signal RFP. In the period T2, the peak detection circuit 1082 determines the peak value of the component SS2 of the magneto-optical signal RFD by the fixed clock CLKk.
To obtain a component P2 of the peak value signal RFP. Then, the peak detection circuit 1082 outputs the detected peak value signal RFP to the averaging circuit 1083.

The averaging circuit 1083 is the peak detection circuit 1
082, and receives the 8T detection signal DTS from the timing generation circuit 1084. The averaging circuit 1083 calculates the average value of the component P1 of the peak value signal RFP input during the period T1, outputs the calculated value as the amplitude of the component SS1 of the magneto-optical signal RFD, and outputs the peak value signal input during the period T2. The average value of the component P2 of the RFP is calculated and output as the amplitude of the component SS2 of the magneto-optical signal RFD.

The laser driving circuit 111 includes a delay circuit 108
Optical head 1 in synchronization with the delay clock output from
01, the peak detection circuit 1082 and the averaging circuit 1083 in the present invention.
The delay clock for generating the pulse light is determined so that the amplitude of the magneto-optical signal detected by the above becomes maximum. The determination of the delay clock is performed using the 8T signal recorded in the header area of the magneto-optical recording medium 10.

Then, an operation for obtaining a delay clock at which the amplitude of the magneto-optical signal is maximized will be described.

Referring to FIG. 9, delay circuit 1085 generates fixed clock CLKk obtained by delaying clock CLK input from clock generation circuit 104 by a fixed amount,
The generated clock CLKk is output to the AD converter 1081 and the peak detection circuit 1082. The delay circuit 1085 generates the delayed clocks CLKD1 to CLKDn by delaying the phase of the clock CLK by various delay amounts, and generates the generated delayed clocks CLKD1 to CLKDn.
n is output to the laser drive circuit 111. Then, the laser driving circuit 111 outputs the delayed clocks CLKD1 to CLKD.
n, the semiconductor laser in the optical head 101 is driven, and the optical head 101 converts the pulse light into the magneto-optical recording medium 1.
Reproduce the signal from 0. Then, the peak detection circuit 1082 of the amplitude detection circuit 108 receives the magneto-optical signals RFD1 to RFDn converted into digital signals as shown in FIG. Then, the peak detection circuit 1082 outputs the magneto-optical signal RFD1 during the periods T1 and T2 of the 8T detection signal DTS.
To RFDn is fixed clock CLKk
And outputs the peak value signals RFP1 to RFPn to the averaging circuit 1083. Averaging circuit 1083
Receives the peak value signals RFP1 to RFPn, calculates the average of each peak value, and calculates the average of the
9 is output.

Then, based on the input average value, CPU 109 detects the delay clock at which the largest average value is obtained. 9 and 10, since the average value of the peak value signal RFPk is the largest,
CPU 109 detects delayed clock CLKDk when peak value signal RFPk is obtained. And CPU
109 determines the delay amount of the detected delay clock CLKDk with respect to the clock CLK, and outputs the calculated delay amount to the delay circuit 1085.

The delay circuit 1085 generates a delayed clock CLKDk obtained by delaying the clock CLK by the delay amount input from the CPU 109 and outputs the generated delayed clock CLKDk to the laser drive circuit 111. The laser drive circuit 111 has a delay clock CLK
The semiconductor laser in the optical head 101 is driven based on Dk. As a result, the optical head 101 irradiates the magneto-optical recording medium 10 with pulse light having the maximum amplitude of the magneto-optical signal.

The amplitude detection circuit of the magneto-optical disk device 100 may be the amplitude detection circuit 108A shown in FIG. The amplitude detection circuit 108A includes a bottom detection circuit 1086 and an averaging circuit 10 in addition to the amplitude detection circuit 108 shown in FIG.
87 and a difference circuit 1088 are added, and the rest is the same as the amplitude detection circuit 108. The bottom detection circuit 1086 receives the magneto-optical signal RF from the AD converter 1081.
Receiving the fixed clock CLKk from the delay circuit 1085
Receiving the 8T detection signal DTS2 from the timing generation circuit 1084. The 8T detection signal DTS2 is a signal for detecting the component SS3 of the magneto-optical signal RFD shown in FIG. 8, and is a signal obtained by inverting the 8T detection signal DTS.
Then, the bottom detection circuit 1086 outputs the 8T detection signal DT
While S2 is at the H level, the bottom value of the magneto-optical signal RFD input from the AD converter 1081 is detected in synchronization with the fixed clock CLKk. Then, the bottom detection circuit 1086 outputs the detected bottom value signal RFB to the averaging circuit 1087. This bottom value signal RFB is similar to the peak value signal RFP shown in FIG.
The averaging circuit 1087 receives the bottom value signal RFB from the bottom detection circuit 1086, and
Receive the 8T detection signal DTS2. Then, the averaging circuit 1087 averages a plurality of bottom values of the input bottom value signal RFB during the period when the 8T detection signal DTS2 is at the H level.

The difference circuit 1088 includes an averaging circuit 1087
And the average of the peak values from the averaging circuit 1983. Then, the difference circuit 1088
Subtracts the average of the bottom values from the average of the peak values,
The result of the subtraction is output to the CPU as the amplitude of the magneto-optical signal.

That is, the amplitude detection circuit 108A is a circuit that determines the difference between the peak value and the bottom value of the magneto-optical signal as the amplitude of the magneto-optical signal. The operation for determining the delay clock that maximizes the amplitude of the magneto-optical signal is performed by the amplitude detection circuit 10.
Same as 8.

With reference to FIG. 12, the operation for finding a delayed clock that maximizes the amplitude of the magneto-optical signal will be described.
When the operation starts, initialization is performed (step S1). That is, the clock delay value = 0, the amplitude of the magneto-optical signal = 0, and the optimal clock delay value = 0.
Is set. Then, the delay value of the clock CLK is increased by "+1" (step S2). A fixed amount of 8T signal (for one block) is reproduced using the pulse light generated based on the delay clock (step S).
3).

Thereafter, the amplitude value of the magneto-optical signal is detected by the above-described method (step S4), and it is determined whether the detected amplitude is the maximum (step S5). If the detected amplitude is not the maximum, the process proceeds to step S7. If the detected amplitude is the maximum, the detected amplitude is set to the maximum value, and the clock delay when the amplitude is obtained is set as the optimal clock delay (step S6).

Then, in step S5, when the detected amplitude is not the maximum, or after step S6, it is determined whether or not the delay amount of the delay clock exceeds the limiter value (step S7). If not, steps S2 to S7 are repeated. Then, if the delay amount exceeds the limiter value in step S7, the measurement for obtaining the optimum delay amount of the delay clock ends (step S8). In step S8,
The obtained delay amount is set in the delay circuit 1085 of the amplitude detection circuits 108 and 108A (step S9), and all operations are completed (step S10).

The magneto-optical disk device according to the present invention may be a magneto-optical disk device 200 shown in FIG.
The magneto-optical disk device 200 includes the amplitude detection circuit 108 of the magneto-optical disk device 100 shown in FIG.
4 and the other is a magneto-optical disk drive 1
Same as 00. In the magneto-optical disk device 200, the reproduction signal amplifying circuit 102 outputs the magneto-optical signal amplified to a predetermined level only to the signal processing circuit 105, and the signal processing circuit 105 corrects the error number of the magneto-optical signal. The number of errors is obtained by performing correction, and the obtained number of errors is output to the CPU 109.

The signal generation circuit 114 includes a timing generation circuit 1084 and a delay circuit 1085 shown in FIG. Therefore, the signal generation circuit 114 outputs the fine clock mark detection signal F from the FCM detection circuit 103.
An 8T detection signal DTS is generated based on the CM, and the generated 8T detection signal DTS is output to the signal processing circuit 105. Further, the signal generation circuit 114 outputs a fixed clock CLKk obtained by delaying the clock CLK to the signal processing circuit 105. Further, the signal generation circuit 114
Under the control from step 9, the clock CLK input from the clock generation circuit 104 is delayed, and the delayed clock is output to the laser drive circuit 111.

In the magneto-optical disk device 200, the optimum delay amount in the delay clock for determining the timing at which the optical head 101 emits the pulse light is determined by the number of errors of the magneto-optical signal reproduced from the magneto-optical recording medium 10. It is determined to be less than the number. Therefore, when obtaining the optimum delay amount in the delay clock, the CPU 1
09 controls the signal generation circuit 114 to generate the delayed clocks CLKD1 to CLKDn whose phases have been changed.
Then, the delay circuit 1085 outputs the delay clock CLKD1
ＣＬＫCLKDn are generated and output to the laser drive circuit 111. The laser drive circuit 111 drives a semiconductor laser (not shown) in the optical head 101 based on the input delayed clocks CLKD1 to CLKDn, and
1 irradiates the magneto-optical recording medium 10 with pulsed light.

A magneto-optical signal reproduced by irradiating the magneto-optical recording medium 10 with pulse light is input to a signal processing circuit 105 via a reproduced signal generating circuit 102. Signal processing circuit 1
Numeral 05 converts an input magneto-optical signal from an analog signal to a digital signal, cuts, decodes, and corrects errors in high and low frequencies in synchronization with a fixed clock CLKk from the signal generation circuit 114. , And outputs the obtained error number to the CPU 109.

The CPU 109 determines the delay amount of the delay clock in which the number of errors from the signal processing circuit 105 is smaller than the predetermined number as the optimum delay amount, and sets the determined delay amount in the delay circuit 1085 of the signal generation circuit 114. I do. The rest is the same as the description of the magneto-optical disk device 100.

Referring to FIG. 14, magneto-optical disk drive 2
The operation for obtaining the optimal delay amount at 00 will be described. The flowchart shown in FIG. 14 differs from the flowchart shown in FIG. 12 in that steps S4 to S6 are replaced with steps S14 to S16, respectively.
Is the same as the flowchart shown in FIG.

After step S3, the number of errors in the reproduction signal RF is detected (step S14). And CPU1
09 determines whether the number of errors input from the signal processing circuit 105 is smaller than the minimum number of errors (step S15). If the number of errors is not smaller than the minimum number of errors, the process proceeds to step S7. When it is determined in step S15 that the number of errors is smaller than the minimum number of errors, the CPU 109 sets the input number of errors as the minimum number of errors, and determines the amount of delay of the delay clock when the number of errors is obtained. Set the optimal delay amount (step S1
6). Others are as described in FIG.

In FIG. 14, it has been described that the optimum delay amount of the delay clock is determined so that the number of errors in the reproduced signal is minimized. The optimal delay amount of the clock may be determined.

According to the embodiment of the present invention, the magneto-optical disk device generates pulsed light so that the amplitude of the reproduced signal is maximized or the number of errors in the reproduced signal is smaller than a predetermined number. Therefore, the signal can be accurately reproduced from the magneto-optical recording medium.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0065]

According to the present invention, a magneto-optical disk drive generates pulsed light such that the amplitude of a reproduced signal is maximized or the number of errors in the reproduced signal is smaller than a predetermined number. Since the delay amount of the delay clock is determined, the signal can be accurately reproduced from the magneto-optical recording medium.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a data format of a magneto-optical recording medium.

FIG. 2 is a diagram for explaining a segment structure of a magneto-optical recording medium.

FIG. 3 is a schematic block diagram of a magneto-optical disk drive according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining reproduction of data from a preformat area and a user data area.

FIG. 5 is a block diagram of a clock generation circuit shown in FIG. 3;

FIG. 6 is a diagram for explaining generation of a fine clock mark detection signal and a clock.

FIG. 7 is a block diagram of the amplitude detection circuit shown in FIG. 3;

FIG. 8 is a timing chart of signals in the amplitude detection circuit shown in FIG. 7;

9 is a timing chart of signals in the amplitude detection circuit shown in FIG. 7;

FIG. 10 is a timing chart of signals in the amplitude detection circuit shown in FIG. 7;

11 is another block diagram of the amplitude detection circuit shown in FIG.

FIG. 12 is a flowchart for optimizing a delay amount of a delay clock.

FIG. 13 is another schematic block diagram of the magneto-optical disk drive according to the embodiment of the present invention.

FIG. 14 is another flowchart for optimizing the delay amount of the delay clock.

[Explanation of symbols]

1 groove, 2 lands, 3, 3A, 3B fine clock mark, 4 to 9 wobbles, 10 magneto-optical recording medium, 10A, 20A, 30A, 1020A, 1020
B, 1020C, 1020D, 1020E, 1020F
Area, 40, 50 circuits, 100, 200 magneto-optical disk drive, 101 optical head, 102 reproduction signal amplification circuit, 103 FCM detection circuit, 104 clock generation circuit, 105 signal processing circuit, 106 servo circuit,
107 spindle motor, 108, 108A amplitude detection circuit, 109 CPU, 110 magnetic head drive circuit, 111 laser drive circuit, 112 encoder, 1
13 magnetic head, 114 signal generation circuit, 400, 50
2,505 subtractor, 500,501,503,504
Adder, 1020 photodetector, 1041 phase comparator, 1042 LPF, 1043 VCO, 1044
1/532 frequency divider, 1081 AD converter, 1082
Peak detection circuit, 1083, 1087 averaging circuit, 1
084 timing generation circuit, 1085 delay circuit, 1
086 Bottom detection circuit, 1088 Difference circuit.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Kenji Nakao 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Yoichi Tsuchiya 2-5-2 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. F term (reference) 5D075 AA03 CC23 CD09 DD06

Claims (5)

[Claims] 1. A magneto-optical disk device for reproducing a signal from a magneto-optical recording medium using a laser beam, wherein a clock generating circuit detects a fine clock mark formed on the magneto-optical recording medium and generates a clock. A delay circuit for delaying a clock generated by the clock generation circuit to generate a delayed clock and a fixed clock; and irradiating the magneto-optical recording medium with pulsed light synchronized with the delayed clock, the magneto-optical recording An optical head for detecting a magneto-optical signal from a medium, an amplitude detecting circuit for detecting the amplitude of the magneto-optical signal detected by the optical head in synchronization with the fixed clock, and when changing the delay amount of the delay clock Receiving the amplitude of the magneto-optical signal from the amplitude detection circuit, and determining the delay amount of the delay clock at which the received amplitude has a maximum value. Magneto-optical disk device and a delay amount determining circuit for setting the determined delay amount in the delay circuit. 2. An A / D converter for converting a magneto-optical signal from the optical head from an analog signal to a digital signal in synchronization with the fixed clock and outputting a reproduction signal, wherein the amplitude detection circuit outputs a reproduction signal. A peak detection circuit for detecting a peak value of the reproduced signal at each timing; receiving a plurality of peak values detected by the peak detection circuit; calculating an average value of the received plurality of peak values; and outputting the amplitude 2. The magneto-optical disk drive according to claim 1, further comprising an averaging circuit. 3. An A / D converter for converting a magneto-optical signal from the optical head from an analog signal to a digital signal in synchronization with the fixed clock and outputting a reproduction signal, the amplitude detection circuit comprising: A peak detection circuit for detecting a peak value of the reproduced signal at each timing; receiving a plurality of peak values detected by the peak detection circuit; calculating an average value of the received plurality of peak values; A first averaging circuit for outputting, a bottom detection circuit for detecting a bottom value of the reproduced signal at each timing of the fixed clock, a plurality of bottom values detected by the bottom detection circuit, and a plurality of received bottom values A second averaging circuit that calculates an average value of the bottom values of and outputs an average bottom value, and a difference between the average peak value and the average bottom value. 2. The magneto-optical disk drive according to claim 1, further comprising: a difference circuit that calculates the amplitude and outputs the amplitude. 4. A magneto-optical disk device for reproducing a signal from a magneto-optical recording medium using a laser beam, wherein a clock generation circuit generates a clock by detecting a fine clock mark formed on the magneto-optical recording medium. A delay circuit for delaying a clock generated by the clock generation circuit to generate a delayed clock and a fixed clock; and irradiating the magneto-optical recording medium with pulsed light synchronized with the delayed clock, the magneto-optical recording An optical head that detects a magneto-optical signal from a medium, an error detection circuit that detects the number of errors of the magneto-optical signal detected by the optical head in synchronization with the fixed clock, and a delay amount of the delay clock is changed. The error number of the magneto-optical signal at that time is received from the error detection circuit, and the received error number becomes smaller than a predetermined number. Determining the delay amount of the clock, a magneto-optical disk device and a delay amount determining circuit for setting the amount of delay to the decision on the delay circuit. 5. The magneto-optical signal detected by the optical head when the delay amount of the delay clock is changed is a signal of a predetermined pattern recorded on the magneto-optical recording medium. 5. The magneto-optical disk device according to any one of 4.