JPH1055542A - Optical disk recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm a data recording state simultaneously with recording without necessities of increasing a laser diode in number and gaining revolving speed. SOLUTION: This device is for recording and reproducing data by using an overwritable optical disk. The optical disk 20 is irradiated with a laser beam from the laser diode LD via a diffraction grating 14, and plural beam spots are image-formed on the same track, and main return light of a central main laser beam and subreturn light of the following sublaser beam are detected out of the laser beam, and their outputs are supplied to an amplitude modulation part 50 respectively, and then the detecting output CMO based on the subreturn light is reversely modulated by the detecting output RO based on the main return light. A confirmation data is reproduced based on this reverse modulation output at the time of recording mode. Consequently, simultaneously with recording, the data recording state can be confirmed without necessities of increasing the laser diode LD in number and gaining the revolving speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus using an overwritable optical disk. Specifically, after reading in the recording mode is realized without using the single reading mode by confirming data recording by using the detection output of the side beam (sub return light) in the recording mode. It is.

[0002]

2. Description of the Related Art As is well known, address data and the like are preformatted (precoded) for each sector in an optical disk (magneto-optical disk) employing an overwritable optical modulation method.

[0006] The magneto-optical disk shown in FIG. 6A has a recording area divided into an inner recording area (channel 1) and an outer recording area (channel 2), and each recording area has a plurality of tracks. It is composed of sectors, for example, 42 sectors.

As shown in FIG. 6B, one sector is composed of a precoded address area (address section) ADD and a write area (data recording section) DATA for recording data.

[0005] As shown in FIG. 1B, the address portion ADD has three address data of the same content following the sector marker SM.
Formed repeatedly. The repetition is performed three times to ensure that the address data can be read even when a reading error occurs. This address data is composed of VFO data, an address marker AM, and identification data ID. VF0 (variable frequency osillator) is a single-frequency signal used to pull in the operation of a clock generating PLL oscillator to generate a reference signal (reference clock). Following the address data, postamble data PA is recorded.

Each of these address data is preformatted data, and data is formed by bits. Following the address part ADD, the data recording part DATA
A test area is provided at the beginning of the data recording section DATA. In the test area, APC data is used for power level control for the laser diode, followed by VFO data VF04 (VFOI to VFOI).
F03) is recorded. Data recording section DA
At the end of the TA, a buffer area (non-recording part) is provided to clarify the boundary with the address part ADD. The illustrated number of sectors and the number of bytes constituting one sector are merely examples.

The overwritable magneto-optical disk 1 is constructed by laminating two magnetic layers (auxiliary layer and memory layer) 3 and 4 having different coercive force and Curie temperature on a base 2 as shown in FIG. Have been. Then, while applying two external magnetic fields, data is recorded back and forth between the two Curie points. For this reason, data recording is usually performed by a pulse train method as shown in FIG. 8, and data is recorded by alternately applying the recording power Pw and the erase power Pe.

Normally, when the laser power is 1/2 of the recording power Pw, data cannot be recorded even if the laser is irradiated. Therefore, a laser beam of 1/2 or less of the recording power Pw is always irradiated. No problem.

Similarly, in the case of a phase-change type optical disk, data is recorded by overwriting, and the recording method is also a pulse train method.

[0010]

By the way, in order to confirm whether or not the data has been recorded normally, conventionally, after recording the data, the reproducing mode is set, and the reproduced data is confirmed. Therefore, it is necessary to rotate the disk at least twice, and it takes a long time to check the data, and the checking operation is troublesome.

If the disk is rotated at double speed, the checking operation is completed in one rotation, which is convenient. However, in this case, the data transfer rate is reduced by half.
A recording / reproducing device with a high transfer rate cannot be realized.

If an optical pickup system for data recording and an optical pickup system for data confirmation are independently provided, write-after-read can be realized without sacrificing the transfer rate.
However, this has the disadvantage that the optical pickup system becomes complicated.

In view of the above, the present invention has been made to solve the above-mentioned conventional problems, and is intended to provide an after-read system for confirming recorded data which has a simplified structure and is realized without sacrificing transfer efficiency. A recording / reproducing apparatus is proposed.

[0014]

In order to solve the above-mentioned problems, in the optical disk recording / reproducing apparatus according to the present invention, data is recorded / reproduced using an overwritable optical disk. In an optical disk recording / reproducing apparatus, a laser beam from a laser diode as a light source is irradiated onto an optical disk via a diffraction grating, so that a plurality of beam spots are formed on the same track, and Of the beams, the main return light from the central main laser beam and the detection output regarding the sub return light from the following sub laser beam are supplied to the modulator, respectively, and the detection output based on the sub return light is output from the main return light. Inverse modulation is performed with the detection output based on the return light, and the confirmation data in the recording mode is reproduced based on the inverse modulation output. Characterized in that it made so that.

According to the present invention, an optical system is configured such that a laser beam is divided into three parts by a diffraction grating and these laser beams form an image on the same track. Then, a sub laser beam (side beam) following the main laser beam is used as a laser beam for confirming recording data. The photodiode receives the return light (sub return light) of the side beam.

Since data is recorded by the pulse train method, in the recording mode, the recording power and the erase power alternately come and go, and the confirmation signal detected by the photodiode is based on the pulse train data information. It is obtained in a state of being modulated (AM modulation). Therefore, inverse modulation is applied to this confirmation signal.
The signal for inverse modulation is a reproduced signal formed from the return light of the main laser beam, and is a signal that has been subjected to AM modulation.

If inverse modulation is performed, a high-frequency signal having an eye pattern having a stable amplitude is obtained. By decoding this signal, recorded data can be reproduced, and thus can be used for confirming recorded data.

Thus, write-after-read can be realized without complicating the optical system, and when data recording is insufficient, processing such as re-recording can be performed.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention applied to a disk recording / reproducing apparatus using an overwritable magneto-optical disk. This will be described in detail.

FIG. 1 is a system diagram of a main part showing an outline of an optical system used in the disk recording / reproducing apparatus and a signal processing system, and shows a laser beam (laser light) emitted from a laser diode LD as a light source. Is the collimator lens 12
After being converted into parallel light, the light is split into a plurality of beams by a diffraction grating (grating) 14.

In this embodiment, as shown in FIG. 2, a pair of two side beams (primary light) Bsf and Bsb are obtained with respect to a main laser beam (zero-order light) Bm. These three
The two laser beams are adjusted so as to scan on the same track, respectively, and the beam spot interval W is selected so as not to be thermally affected by the preceding and succeeding beams. In this example, it is set to be approximately 16 μm from the relationship with the wavelength of the laser diode LD.

These are the wavelength λ of the laser diode LD, the focal length fo of the objective lens 18, and the pitch p of the diffraction grating 14.
Is, for example, λ = 685 × 10 ⁻⁸ m fo = 3 mm p = 7.961 inch / mm, the beam spot interval W is W = λ · fo · p = 16.36 μm. When the spot interval is wide enough, the data recorded by the main beam is completely cooled and stable, so even if after-read by the succeeding side beam, the data recorded immediately before is correctly reproduced. Because you can.

As the diffraction grating 14, a transmission type amplitude grating, a transmission type phase grating, a reflection type diffraction grating, or the like can be used.

The laser beam having passed through the diffraction grating 14 is irradiated on a magneto-optical disk 20 via a beam splitter 16 and an objective lens 18. A magneto-optical disk 20 having the same configuration as the optical disk 1 shown in FIG. 7 is used.

Reference numeral 22 denotes an actuator of the optical pickup. A part of the laser beam that has passed through the beam splitter 16 is deflected by the deflection beam splitter 24 and the cylindrical lens 2.
The light is guided to the photodiode 28 through 6, and the laser light amount is monitored. The detection output is supplied to the data modulator 32 via the amplifier 30. Recording data is supplied from a terminal 34 to the data modulator 32, and the laser diode LD is pulse-driven (excited) by this, and is controlled by a light quantity detection output so that the laser power becomes a predetermined level.

The return light of the laser beam reflected by the magneto-optical disk 20 is guided to the pair of photodetectors 40 and 44 via the beam splitter 16 and the cylindrical lens 36. Each is composed of a pair of photodiodes, and one photodetector 40 obtains a sum output RO used as a reproduction output of the address unit ADD and a difference output MO used as a reproduction output of the data recording unit DATA. These are finally supplied to a signal processing unit 42 for obtaining recording data.

The other photodetector 44 returns light (sub-return light) from the succeeding side beam Bsb of the side beams.
Is detected. The return light causes the data recording section DAT.
Since information (after-read information) related to A is to be obtained, a difference between light outputs obtained from a pair of photodiodes constituting the photodetector 44 is detected, and the difference output CMO is used as a signal for confirming recording data. Used as

Since data is recorded by the pulse train method as described later, the laser power of the laser diode LD is set to the recording power P in the recording mode.
w and the erase power Pe are alternately repeated, so that this repetitive component becomes an AM component and the difference output CMO
Appears in

That is, in the normal reproduction mode, a constant level of laser power is applied except during the APC period as shown in FIGS. 4A and 4B. The sum output RO detected from the return light (main return light) of the main beam by this laser power is as shown in FIG. 4C, from which address information (ADD) can be obtained. Similarly, the difference output (data reproduction output) MO detected from the return light of the main beam is as shown in FIG. 4D, from which the recorded data information can be decoded.

On the other hand, in the recording mode, the laser power is modulated by the recording power Pw and the erase power Pe for pulse train recording. In this case, the laser power applied to the laser diode LD is changed. Has changed as shown in FIG. 5B.

Therefore, in the difference output CMO which is the same output as the data reproduction output in the recording mode, the change in the laser power in the data recording section DATA is output as an AM component as shown in FIG. 5C. The data to be recorded is shown in FIG.
Therefore, since the AM modulated wave and its modulated wave (carrier) are the same signal,
The components are obtained superimposed on each other, which is the same as the absence of carrier. In other words, this AM component has the same output as that subjected to phase modulation. Therefore, even if the waveform is equalized and shaped in a state including the AM component, the waveform cannot be correctly shaped, and therefore it is not possible to directly return to the recording data from the difference output CMO including the AM component.

As described above, according to the present invention, the modulation section 50 shown in FIG. 1 is provided so as to cancel the AM component.
The modulator 50 is provided with a sum output (reproduction output) RO as shown in FIG.
, Inverse modulation is applied to the difference output CMO.

The difference output MO from the main beam is given to the modulator 50 in addition to the difference output CMO because the sum output RO when the laser power shown in FIG. 5B is given in the data area. This is because the side beam is reflected at a level corresponding to the laser power, and the same waveform as that of the pulse train is obtained.

FIG. 3 shows a specific example of the modulator 50.
The terminal 40a has a sum output R formed by the main beam.
O is supplied to the terminal 40b, and the difference output MO also formed by the main beam is supplied to the terminal 40b.
The difference output CMO formed from the side beam is given to a.

The respective outputs are supplied to the clamp circuits 58 to 62 via the preamplifiers 52 to 56, and are controlled so that the level in the APC period becomes the reference level REF using the APC period. Among the clamped outputs, the difference output CMO is added to the AM modulator 64 together with the sum output RO.
And the difference output CMO is inversely modulated by the sum output RO. The AM modulator 64 operates only in the data recording mode, and the AM component of the differential output CMO is removed by the inverse modulation process (see FIG. 5E). However, since each edge component of the pulse train remains as it is, a spike noise NS as shown in FIG. 5E remains. The spike noise NS does not affect the data decoding process.

The difference output CMO from which the AM component has been removed and the difference output MO relating to the main beam are supplied to a switch 66.
In the data recording mode, the terminal a is selected and the difference output CMO for recording data confirmation is output, and in the other modes (reproduction mode), the terminal b is selected. Therefore, the mode signal is given to the terminal 67 as the switching signal.

The switching output and the sum output RO are respectively supplied to the signal processing unit 42, and in the normal reproduction mode, the sum output RO from the main beam and the difference output MO are output.
Thus, the data is decoded and the recorded data is reproduced.

In the data recording mode, the outputs RO and MO from the main beam are not used for signal processing. Instead, the difference output CMO related to the side beam is supplied to the signal processing unit 42, where signal processing necessary for decoding processing such as waveform equalization processing, waveform shaping processing, and comparison processing is performed, and finally the recording data is demodulated. Is done.

The demodulated record data thus written and read is used for data confirmation, and the result is displayed on the display unit 70. When the data is correctly recorded, for example, a display of "normal" is performed, and when the data is not correctly recorded, a display such as "re-recording" is performed, and processing such as re-recording is performed.

In the above-described embodiment, a case where a magneto-optical disk having a two-layer structure is used as an overwritable optical disk has been exemplified. However, it is apparent that the present invention can be similarly applied to a phase-change type optical disk.

[0041]

As described above, according to the present invention, after-reading can be performed almost simultaneously with data recording without increasing the number of laser diodes or doubling the number of rotations of the disk. Confirmation of recorded data can be performed without securing. Therefore, the confirmation time can be reduced as compared with the conventional case, and the transfer rate does not deteriorate. .

Of course, since a single laser beam is divided into a plurality of parts by using a diffraction grating, the laser diode and its peripheral mechanism can be simplified, and the cost can be reduced accordingly. It is convenient. Therefore, the present invention is extremely suitable for application to a disk recording / reproducing apparatus using an overwritable magneto-optical disk, a phase change optical disk, or the like.

[Brief description of the drawings]

FIG. 1 is a diagram of an optical system showing an embodiment of a recording and reproducing apparatus for an optical disk according to the present invention.

FIG. 2 is a diagram illustrating an example of beam division.

FIG. 3 is a system diagram illustrating an example of a modulation unit.

FIG. 4 is a waveform diagram in a reproduction mode.

FIG. 5 is a waveform diagram in a data confirmation mode (data recording mode).

FIG. 6 is a diagram illustrating an example of a recording format of an optical disc.

FIG. 7 is a cross-sectional view showing a structural example of a magneto-optical disk capable of overwriting.

FIG. 8 is an explanatory diagram of a pulse train recording method.

[Explanation of symbols]

LD: laser diode, 14: diffraction grating, 2
0 ... optical disk, 40, 44 ... photodetector, 50
... Modulation unit, RO ... Sum output of main beam, MO
... Difference output of main beam, CMO ... Difference output of side beam, 64AM modulator

Claims (4)

[Claims] 1. An optical disk recording / reproducing apparatus for recording / reproducing data using an overwritable optical disk, wherein a laser beam from a laser diode as a light source is irradiated onto the optical disk via a diffraction grating, and A plurality of beam spots are formed on the same track, and the main laser beam from the central main laser beam and the sub-return light beam from the following sub-laser beam among the laser beams are detected. The outputs are respectively supplied to the modulators, so that the detection output based on the sub return light is inversely modulated with the detection output based on the main return light, and the confirmation data in the recording mode based on the inverse modulation output. A recording / reproducing apparatus for an optical disk, characterized in that the recording / reproducing apparatus is configured to reproduce the information. 2. The optical disk recording / reproducing apparatus according to claim 1, wherein said optical disk is a magneto-optical disk or a phase-change optical disk employing an overwritable optical modulation method. 3. An optical disk recording / reproducing apparatus according to claim 1, wherein said data recording is performed by a pulse train method. 4. The optical disc recording / reproducing apparatus according to claim 1, further comprising a photodetector for detecting the sub return light for confirming data at the time of recording.