JP2565207B2 - Optical disk device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Industrial field B Outline of the invention C Prior art D Problems to be solved by the invention (Figs. 6 to 12) E Means for solving problems (Figs. 1 to 5) F action (Figs. 1 to 5) G embodiment (G1) First embodiment (Figs. 1 and 2) (G2) Second embodiment (Figs. 3 to 5) (G3) ) Other Embodiments H Effect of the Invention A Field of Industrial Application The present invention relates to an optical disk device, and is suitable for application to, for example, a magneto-optical disk device.

B. SUMMARY OF THE INVENTION The present invention relates to an optical disk device configured to perform overwriting by using two laser beams.
Each phase difference is detected using the return light of the two laser beams, and a clock signal corresponding to the recording data is created using one of the laser beams, and the phase difference between the clock signal and the two laser beams is generated. By controlling each laser beam based on
It is possible to realize an optical disc device that can surely overwrite.

C Conventional Technology Conventionally, in a magneto-optical disk device, a method using an optical modulation method or a magnetic field modulation method has been proposed as a recording method for recording predetermined information data on a magneto-optical disk which is a magneto-optical recording medium. There is.

That is, the optical modulation system is
This is a method of recording information data on a magneto-optical disk by applying a constant recording bias magnetic field and irradiating a laser beam modulated by the information data.

On the other hand, the magnetic field modulation method is a method of recording information data on the magneto-optical disk by continuously irradiating the magneto-optical disk with a laser beam and inverting the bias magnetic field based on the information data. Is.

D. Problems to be Solved by the Invention By the way, for example, when new information data is recorded on a magneto-optical disk on which predetermined information data is recorded by an optical modulation method (hereinafter referred to as additional writing), The write-once area is magnetized in one direction in advance to erase the recorded data, and then the laser beam modulated based on new information data is partially irradiated.

However, according to this additional recording method, even when rewriting the recorded content of one track on the magneto-optical disk,
First, in order to erase the recorded data that has been written, it is necessary to rotate the magneto-optical disk once, and then to write new information data, it is necessary to further rotate the magneto-optical disk once. Since the magneto-optical disk has to be rotated twice for additional recording of data, there is a problem that additional recording cannot be performed quickly.

Therefore, it is conceivable to record new information data on the magneto-optical disk without erasing the recorded data written on the magneto-optical disk (hereinafter referred to as overwriting). A method (including a method that requires the same additional writing time as the overwrite method) has been proposed.

First, as shown in FIG. 6, two magneto-optical heads are formed by combining laser optical heads 2A and 2B and permanent magnets 3A and 3B arranged on the front and back sides of the magneto-optical disk 1.
4A and 4B are provided separately in the circumferential direction of the recording track TR,
Use the first magneto-optical head 4A preceding the direction of rotation a of the magneto-optical disk 1 for erasing only and magnetize it in one direction, and use the second magneto-optical head 4B on the trailing side for recording. Has proposed a method of additionally writing at the same speed as overwriting. However, in this case, a peripheral device such as a servo device is required for each of the magneto-optical heads 4A and 4B, and there is a problem in that the configuration is complicated and expensive.

Secondly, as shown in FIG. 7, a method of overwriting with a conventional magneto-optical disk device of the magnetic field modulation type has been proposed. By the way, in a magneto-optical disc, the recording layer has a protective layer and is deeper than the surface. Therefore, for overwriting, for example, 300 to 500 on the surface of the magneto-optical disc.
It is necessary to invert a large external magnetic field of about [Oe] at a high frequency based on information data.

However, in practice, in the electromagnet 5 for generating a large external magnetic field, that is, in the electromagnet having a large inductance, high speed reversal of the magnetic field is difficult due to this inductance, and eventually overwriting is possible, but high speed processing is possible. There was a problem that I could not.

Thirdly, as shown in FIG. 8, laser beams LD0 and LD1 obtained by halving the laser beam from one optical head 2 are applied to two adjacent recording tracks TR0 and TR1 on the magneto-optical disk 1. At the same time, two permanent magnets 3C and 3D arranged so as to give magnetic fields having polarities different from each other are arranged on the back surface side of the magneto-optical disk 1 corresponding to the two laser beams LD0 and LD1. Record track T with LD0
A method of erasing recorded data on R0 and recording new information data with the other laser beam LD1 has been proposed. However, according to this method, in the case of additionally recording the recording data on the entire surface of the magneto-optical disk 1, for example, it can be performed at a higher speed than the conventional method, but in the case of additionally recording the information data of only one track, for example. Requires rotating the magneto-optical disk twice like the conventional method,
The speed of additional writing cannot be obtained.

Here, in order to solve the problems of the first, second and third overwrite methods, as shown in FIG.
For example, as one that can form two laser beams LD2 and LD3 from two semiconductor laser diodes that can be independently driven and controlled, the two laser beams LD2 and LD3 are
Irradiation is performed on the same recording track TR on the magneto-optical disk 1 so that they are spaced apart by a predetermined minute interval in the circumferential direction, and the two laser beams LD2 and LD3 correspond to each other on the back surface side of the magneto-optical disk 1. Two permanent magnets 3C and 3D that provide magnetic fields with different polarities are arranged, and this allows the laser beam LD on the leading side with respect to the rotation direction a of the magneto-optical disk 1 to be arranged.
There is proposed a method of erasing the recorded data on the recording track TR in 2 and recording new information data by the laser beam LD3 on the trailing side.

However, as shown in FIGS. 10 and 11, the magneto-optical disk 1 itself is a recording track in which a plurality of 2-byte length servo data SB and a subsequent 16-byte length data area DT, which are embossed dots, are combined. The TR is concentric on the so-called CAV (constant argument verosit
recording track TR10 on the outer circumference side.
The recording density increases as the recording track TR11 on the inner circumference side is reached.

On the other hand, the first and second optical heads 2C are formed.
The distance between the laser beams LD2 and LD3 is selected to be, for example, a value of 100 [μm] on the magneto-optical disk 1 by the distance of the laser diode of the optical head 2C and the optical system.
Therefore, by using the laser control circuit 10 as shown in FIG. 12, the first laser beam LD2 for erasing and the second laser beam LD2 for recording are used.
The laser beam LD3 is driven and controlled.

That is, the laser control circuit 10 comprises an erasing system 10A for controlling the first erasing laser beam LD2 and a recording system 10B for controlling the second erasing laser beam LD3.

The erasing system 10A and the recording system 10B have almost the same configuration,
First, in the erasing system 10A, except during erasing, the first laser beam LD2, which is a light emission output for reproduction, is irradiated, and the return light of the first laser beam LD2 is received by the first photodetector 12A. a first light receiving output S _PD1 amplifier circuit 13A
Is input to the erase address control circuit 15A via the, and the peak detection circuit 14A performs peak detection to obtain a detection output S _SB1 at the timing of the servo data SB.

Erase address control circuit 15A, for example, in a microcomputer configuration, by reproducing the first reception output S _PD1, give the address data composed of Enbosupitsuto previously formed for every predetermined number of servo data SB and the data area DT ,
By referring to the address data and the servo data SB, for example, an erase control signal CNT _ER rising in a data area DT corresponding to an erase instruction ER input from a system control circuit (not shown) is sent to the erase timing generation circuit 17A. It is done like this.

The detection output S _SB1 obtained from the peak detection circuit 14A is input to a phase locked loop (PLL) circuit 16A to which a rotation frequency signal obtained from, for example, a spindle motor is referred to, followed by a servo timing signal S _TM1 obtained therefrom. It is input to the erase timing generation circuit 17A.

The erase timing generation circuit 17A includes an erase control signal CNT _ER and a PLL circuit 16A input from the erase address control circuit 15A.
The laser drive circuit 18 generates the erase signal P _ER1 which is a pulse signal based on the servo timing signal S _TM1 obtained from
The first laser diode 19A is driven and controlled via A, and thus the data area DT following the predetermined servo data SB on the recording track TR can be erased.

On the other hand, the recording system 10B forms the second laser beam LD3 having a light emission output for reproduction except when recording, and the return light of the laser beam LD3 is used as the second photodetector 1.
2B, the second received light output _SPD2 is sent to the recording address control circuit 15B through the amplifier circuit 13B, and the servo timing signal _STM2 is obtained through the peak detection circuit 14B and the PLL circuit 16B, which is subsequently recorded. Timing generator 17B
To enter.

The recording address control circuit 15B has, for example, a micro-computer configuration, reproduces the second light receiving output _SPD2 to obtain address data and servo data SB, and refers to the address data and servo data SB, for example, system control An information data signal DATA obtained by modulating information data in a predetermined system in the circuit is sent to the recording timing generation circuit 17B at the timing of the data area DT instructed by the system control circuit.

The recording timing generation circuit 17B generates a recording signal P _WR1 which is a pulse signal based on the information data signal DATA given from the system control circuit via the recording address control circuit 15B and the servo timing signal S _TM2 obtained from the PLL circuit 16B. Then, the second laser diode 19B is driven and controlled through the laser drive circuit 18B, and thus the predetermined servo data SB on the recording track TR is set.
Predetermined information data can be recorded in the data area DT that follows.

As a result, by controlling the first laser diode 19A for erasing and the second laser diode 19B for recording independently, the preceding first laser beam LD
After erasing the predetermined data area DT in 2, predetermined information data can be recorded in the erased data area DT by the subsequent second laser beam LD3, whereby overwriting is performed.

However, in this case, the first laser diode 19A for erasing and the second laser diode 19B for recording are independently driven and controlled, which makes the circuit configuration complicated and large in size as a whole. Inevitable, and the first and second laser diodes 19A and 19B
However, there is a problem that the laser diodes 19A and 19B deteriorate in performance due to heat generation.

The present invention has been made in view of the above points, and an object thereof is to propose an optical disk device that uses two laser beams and is capable of overwriting with a simple configuration.

E Means for Solving the Problems In the present invention, in order to solve the above problems, the first laser beam LD2 preceding the recording track TR of the optical disk 1 is used to erase the recorded data, and then continue. In the optical disk device adapted to record new information data by using the second laser beam LD3, the return light of the first and second laser beams LD2 and LD3 is used to record data on the recording track TR. The first and second received light outputs S _PD1 and S _PD2 are obtained, and the first and second received light outputs S _PD1 and S _PD2 are obtained.
First and second laser beams LD2 and LD from _PD1 and S _PD2
The phase difference of 3 is detected, and the first or second received light output S _PD1 or S
A clock signal CLK corresponding to the bit of the recording data is generated based on _PD2 , and the erasing timing of the first laser beam LD2 and the erasing timing of the first laser beam LD2 based on the phase difference between the clock signal CLK and the first and second laser beams LD2 and LD3. The recording timing of the second laser beam LD3 is controlled.

F action First laser beam LD2 for erasing on recording track TR
Erase timing and the recording timing of the second laser beam LD3 for recording new information data on the recording track TR, the first and second received light outputs of the return light of the first and second laser beams LD2 and LD3. By using the clock signal CLK obtained on the basis of the phase difference obtained from S _PD1 and S _PD2 and the first or second received light output S _PD1 or S _PD2 , it is possible to surely perform control while synchronizing. Overwriteable and first and second laser beams LD2 and L
It is possible to prevent the D3 from simultaneously emitting light.

G Embodiment One embodiment of the present invention will be described in detail below with reference to the drawings.

(G1) First Embodiment In FIG. 1 in which parts corresponding to those in FIG. 12 are designated by the same reference numerals, 20 indicates the first embodiment of the laser control circuit according to the present invention as a whole, and an erasing system 20A. first light-receiving output S _PD1 obtained from the first Fuotodeitekuta 12A of the amplifier circuit 1
It is input to the erase address control circuit 15A and the peak detection circuit 14A via 3A, and the erase address control circuit 1
Erase control signal CNT _ER obtained from 5A and peak detection circuit 1
The detection output S _SB1 obtained from 4A is input to the recording / erasing timing control circuit 22.

On the other hand, the second photodetector 12B of the recording system 20B
The second received light output _SPD2 obtained by the above is transmitted through the amplifier circuit 13B to the recording address control circuit 15B and the peak detection circuit 14B.
The information data signal DATA obtained from the recording address control circuit 15B and the detection output S _SB2 obtained from the peak detection circuit 14B are inputted to the recording erasing timing control circuit.
Entered in 22. In addition to this, the detection output S _SB2 obtained from the peak detection circuit 14B is input to the PLL circuit 21.
In this embodiment, PLL circuit 21 on the basis of the detection output S _SB2, as well as phase lock to the detection output S _SB2 made by the servo period, the servo period by dividing the repetition frequency of Detapitsuto on recording tracks TR The clock signal CLK is generated and input to the recording / erasing timing control circuit 22.

As shown in FIG. 2, the recording / erasing timing control circuit 22 controls the erase control based on the input clock signal CLK (FIG. 2 (A)) and erase control signal CNT _ER (FIG. 2 (B)). While the signal CNT _ER has a high level, the erase signal P _ER10 which is a pulse signal having a predetermined pulse width and rising at the falling timing of the clock signal CLK
(FIG. 2 (C)) is generated and sent to the laser drive circuit 18A.

In addition to this, the recording / erasing timing control circuit 22 controls the clock signal CLK (FIG. 2A) and the information data signal DATA.
Based on (FIG. 2 (D)), during the period in which the information data signal DATA has a high level, the recording signal P _WR10 (which is a pulse signal having a predetermined pulse width and rising at the rising timing of the clock signal CLK) FIG. 2 (E)) is generated and sent to the laser drive circuit 18B.

In the case of this embodiment, the first and second laser beams LD2
The distance between LD3 and LD3 is about 100 μm, while
The distance between the servo data SB is about 136 [μm] on the inner circumference side of the magneto-optical disk 1, and about 272 [μ] which is twice the inner circumference side on the outer circumference side.
m] so that the first laser beam LD2 for erasing is selected to precede the second laser beam LD3 for recording by at most 1 data area DT, In the recording / erasing timing control circuit 22, the phase difference is detected based on the first and second detection outputs S _SB1 and S _SB2 obtained from the peak detection circuit 14A of the erasing system 20A and the peak detection circuit 14B of the recording system 20B, The recording and erasing timing is controlled according to the detection result.

As a result, the inside of the predetermined data area DT is erased in advance by the first laser beam LD2 for erasing which precedes as a whole,
The information data can be surely overwritten by the subsequent second laser beam LD3 for recording.

According to the above configuration, the first laser beam LD2 for erasing that precedes and the second laser beam LD3 for recording that follows
Is used for reproduction except during erasing or recording, and the clock signal C is generated by using the return light of the laser beam LD3 for recording.
By generating LK and controlling the timing of recording and erasing based on the clock signal CLK, it is possible to securely erase recorded data with a simple configuration and to record new information data. The device can be realized.

Further, according to the above configuration, the recording signal P _WR10 for driving the recording laser diode 19B is generated at the rising timing of the clock signal CLK, and the erasing laser diode 19A is driven at the falling timing of the clock signal CLK. By generating the erasing signal P _ER10 for the laser diode for recording and erasing, it is possible to control virtually no simultaneous emission of the laser diodes 19B and 19A for recording and erasing, and thus the laser diode generated by the heat generation by the simultaneous emission. 19
It is possible to prevent the performance deterioration of A and 19B.

(G2) Second Embodiment In FIG. 3 in which parts corresponding to those in FIG. 1 are designated by the same reference numerals, 30 indicates a second embodiment of the laser control circuit according to the present invention as a whole, and an erase system 30A And detection outputs S _SB1 and S _SB2 obtained from the peak detection circuits 14A and 14B of the recording system 30B.
Are subjected to phase comparison in the phase comparison circuit 32, and the delay time of the subsequent delay circuit 33 is controlled using the comparison result CP.

The clock signal CLK obtained from the PLL circuit 21 of the recording system 30B is input to the delay circuit 33 together with the recording pulse generation circuit 31B of the recording / erasing timing control circuit 31. As a result, with respect to the clock signal CLK of the recording system 30B. , A erasing system 30A clock signal CLKD delayed by a delay amount τ according to the phase difference between the erasing system 30A and recording system 30B detection outputs S _SB1 and S _SB2 , and a recording erasing timing control circuit that continues this clock signal CLKD. It is supplied to the erase pulse generation circuit 31A of 31.

Here, as shown in FIG. 4, the recording pulse generation circuit 31B of the recording / erasing timing control circuit 31 is inputted at the timing synchronized with the rising edge of the clock signal CLK (FIG. 4 (A)) of the recording system 30B. A recording signal P _WR11 (FIG. 4 (B)), which is a pulse signal corresponding to the information data signal DATA (in the case of FIG. 4, all values “1” are input in FIG. 4), is supplied to the laser drive circuit 18B. Transmitting and erasing pulse generation circuit 3
Supply to 1A.

In addition, the erase pulse generation circuit 31A erases all of the erase control signal CNT _ER (in the case of FIG. 4) which is input at the timing synchronized with the rising edge of the clock signal CLKD (FIG. 4C) of the erase system 30A. The pulse control circuit 40 generates an erase signal P _ER11 composed of a pulse signal according to
It is sent to the laser drive circuit 18A via (FIG. 5).

The pulse control circuit 40 uses the recording signal _PWR11 and the erasing signal _PWR11.
The AND circuit 41 receives the _ER11 and its AND output S _AND
Is input to the first input terminal b and the control terminal of the switch circuit 43 that follows through the mono-multivibrator circuit 42 that outputs a pulse signal having a predetermined pulse width at the falling timing of the input pulse waveform. ing.

The switch circuit 43 selects the first input terminal b during the period in which the logic “H” level value is input to the control terminal, and conversely, during the period in which the logic “L” level value is input. The second input terminal c is selected, and the erase signal P _ER11 is input to the second input terminal c.

This enables the clock signals of the recording system 30B and the erasing system 30A.
When the recording signal P _WR11 and the erasing signal P _ER11 generated based on CLK and CLKD rise at timings where they do not overlap with each other as shown in FIGS. _4B and _4D , the AND output S obtained from the AND circuit 41. _AND is always logical "L"
Because of the level, the output pulse signal S _MM of the mono-multivibrator circuit 42 is always set to the logic "L" level, and the switch circuit 43 selects the second input terminal c, so that the erase signal P _ER11 to be input is input. It is then sent to the laser drive circuit 18A.

On the other hand, in the recording signal P _WR11 and the erasing signal P _ER12 , as shown in FIGS. _4B and _4E , when a partially overlapping period occurs, it is obtained from the AND circuit 41 according to the period. AND output S _AND (Fig. 4 (F))
However, when it rises, an output pulse signal S _MM (FIG. 4 (G)) that rises at the timing of the fall of the _AND output S _AND and has a predetermined pulse width is sent from the mono-multivibrator circuit 42, Thus switch circuit 43 only during the rise period of the output pulse signal S _MM, first by selecting the input terminal b, the output pulse signal S _MM instead of erasing signal P _ER12 inputted erase signal Is sent to the subsequent laser drive circuit 18A.

According to the above configuration, with respect to the clock signal CLK for recording generated by using the return light of the laser beam LD3 for recording, depending on the phase difference between the return light of the laser beams LD3 and LD2 for recording and erasing. CL signal CL for erasing delayed by
By generating KD and controlling the timing of recording and erasing based on the respective clock signals CLK and CLKD, the recorded data can be erased more reliably compared with the configuration of FIG. A magneto-optical disk device capable of recording various information data can be realized.

Further, according to the above configuration, when the rising portions of the recording signal P _WR11 that drives the recording laser diode 19B and the erasing signal P _ER11 that drives the erasing laser diode 19A overlap, the waveform of the erasing signal P _ER11 is shifted. By doing so, a laser diode for recording and erasing
The timings at which 19B and 19A simultaneously emit light can be controlled to practically none, and thus the deterioration of the performance of the laser diodes 19A and 19B caused by heat generation due to simultaneous emission can be prevented.

(G3) Other Embodiments (1) In the above embodiment, the intervals between the servo data are 136 [μm] on the inner circumference side of the magneto-optical disk, 272 [μm] on the outer circumference side, and the first and second The case where the distance between the laser beams is selected to be 100 [μm] has been described, but the relationship between the distance between the servo data and the distance between the laser beams according to the present invention is not limited to this. Even if it is applied, the same effect as the above-mentioned embodiment can be obtained.

(2) In the above embodiment, the light reception output of the recording system is used to generate the clock signal.
The present invention is not limited to this, and the light reception output of the erasing system may be used.

(3) In the above-mentioned embodiment, the case where the present invention is applied to the magneto-optical disk of the CAV system has been described.
It can also be applied to a magneto-optical disk of the (constant lens verosity) system.

(4) In the above embodiments, the case where the present invention is applied to the magneto-optical disk device has been described, but the present invention is not limited to this, and is widely applied to other optical disk devices that can be additionally written. obtain.

H As described above, according to the present invention, the erasing timing of the first laser beam for erasing the recording track and the recording timing of the second laser beam for recording new information data on the recording track are set as follows. The phase difference obtained from the first and second light receiving outputs of the return light of the first and second laser beams and the clock signal obtained based on the first or second light receiving output are used while always synchronizing. By doing so, it is possible to realize an optical disk device capable of reliably overwriting with a simple configuration and preventing the possibility of simultaneous emission of the first and second laser beams.

[Brief description of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention, and FIG.
FIG. 4 is a signal waveform diagram for explaining the operation, FIG. 3 is a block diagram showing a second embodiment of the present invention, FIG. 4 is a signal waveform diagram for explaining the operation, and FIG. 5 is a pulse control circuit. 6 to 9 are schematic perspective views showing magneto-optical disk devices of various overwriting methods, and FIG. 10 is an inner peripheral side and outer peripheral side recording track on the magneto-optical disk. FIG. 11 is a schematic diagram showing a pit of FIG. 11, FIG. 11 is a schematic diagram for explaining a recording track of a magneto-optical disk, and FIG. 12 is a block diagram showing a conventional laser control circuit. 1 ... Magneto-optical disk, 2, 2A, 2B, 2C ... Optical head, 3A, 3B, 3C, 3D ... Permanent magnet, 4A, 4B ... Magneto-optical head, 5 ... Electromagnet, 10, 20, 30 ...... Laser control circuit,
10A, 20A, 30A ... Erasing system, 10B, 20B, 30B ... Recording system,
12A, 12B ... Photo detector, 13A, 13B ... Amplification circuit, 14A, 14B ... Peak detection circuit, 15A ... Erase address control circuit, 15B ... Recording address control circuit, 16A, 16
B, 21 ... PLL circuit, 17A ... Erase timing generation circuit, 1
7B: Recording timing generation circuit, 18A, 18B: Laser drive circuit, 19A, 19B: Laser diode, 22, 31: Recording / erasing timing control circuit, 31A: Erase pulse generation circuit, 31B: Recording pulse generation Circuit, 32 ... Phase comparator, 33 ... Delay circuit, 40 ... Pulse control circuit.

Claims (1)

(57) [Claims] 1. A first laser beam preceding a recording track of an optical disk is used to erase recorded data, and a second laser beam following the first laser beam is used to record new information data. In the optical disk device, the return light of the first and second laser beams is used to generate first and second data corresponding to the recording data on the recording track.
Is obtained, the phase difference between the first and second laser beams is detected from the first and second received light outputs, and the recorded data is pitted based on the first or second received light output. A corresponding clock signal is created, and the erasing timing of the first laser beam and the recording timing of the second laser beam are controlled based on the clock signal and the phase difference between the first and second laser beams. Optical disc device characterized by