JPS6284455A - Photomagnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate erasure in an erasure mode and to make a tracking control means at high accuracy unnecessary by impressing a recording signal on the coil of an external magnetic field impressing means in a recording mode, and controlling light emitting intensity so as to form a recording means recording data. CONSTITUTION:A field coil 26 is so formed that a coil 47 is wound on a part to which a light beam is irradiated, that is, a plate-like ferromagnetic body 46 with the length of a range covering a recording track width, and a signal current corresponding to recording information is flowed in the coil 47 in the recording mode. On a disk 22 each coaxial circular track is divided into plural sectors, which are sorted out at a pair of sectors Si and Si' so that data can be recorded in the recording mode without erasing data in an erasure mode. A pair of selector memories Msn and Msn' are provided for containing recording bits of a pair of selectors Si and Si', and a reproduction signal can be obtained by an output passed through the exclusive OR circuit EXOR of these selector memories Msn and Msn'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording and reproducing apparatus that performs recording by passing a signal current through a coil of an external magnetic field applying means.

[Prior Art] Conventionally, there is a magneto-optical recording and reproducing device as an optical information recording and reproducing device that uses a light beam to record and reproduce information on a recording medium carrying a heat mode material.

This magneto-optical recording/reproducing device uses glass as the recording medium.

Gd, Tb on the surface of a substrate such as PC or PMMA.

A magneto-optical disk carrying a ferromagnetic thin film made of an alloy such as Fe is used. When recording information on such a magneto-optical disk, the magnetization direction of the ferromagnetic thin film on the magneto-optical disk is aligned in advance in one direction perpendicular to the disk surface. continue,
A light beam spot modulated according to information is irradiated onto the magneto-optical disk while applying an external magnetic field in a direction opposite to the aligned magnetization direction of the ferromagnetic thin film. Then, the temperature of the part irradiated by the light beam spot increases due to the energy of the light beam, reaching a temperature higher than the cue point, and the predetermined magnetization direction becomes disordered. As the magneto-optical disk rotates, the portion irradiated by the light beam spot also moves, and the temperature of the irradiated portion decreases. At this time, it is magnetized in the opposite direction to the surroundings by an external magnetic field. In this way, information is recorded on the ferromagnetic thin film as a reversal of the magnetization direction.

One of the above-mentioned methods is a conventional example disclosed in Japanese Patent Application Laid-Open No. 60-35303. This method includes a first beam generating means that generates a recording beam modulated according to information during recording;
A second light beam generating means for generating an unmodulated light beam that becomes an erasing beam and a tracking beam during recording is provided, and an erasing external magnetic field generating means is disposed corresponding to the irradiation position of the erasing beam, Thus, the recording beam, erasing beam, and tracking beam are simultaneously generated by separate generating means.

A configuration diagram of a conventional example is shown in FIG.

An optical pickup (not shown) is disposed facing the magneto-optical disk 1, and an external magnetic field generating means 2 is disposed opposite the optical pickup.

The above-mentioned optical pickup has two light sources (not shown) (a
, b), and when recording for rewriting information, an unmodulated light beam and a light beam modulated according to the information are emitted, and a tracking light beam spot 3 and an erasing light beam spot are respectively emitted on the magneto-optical disk 1. The light beams are focused as a light beam spot 4 for focus control and reproduction, and a light beam spot 5 for recording. At this time, the external magnetic field generating means 2 is in an operating state. The external magnetic field generating means 2 consists of an iron core 8, a coil 9, and a ferromagnetic material 10. A coil 9 is wound around the iron core 8, and when the coil 9 is energized, the upper end of the ferromagnetic material 10 becomes the magnetic pole N and the ferromagnetic material 10. It is magnetized to S. Therefore, the upper end of the ferromagnetic material 10 is magnetized to N and S, and an external magnetic field 11 is generated. Then, the magnetization direction of the recording bit is reversed from downward to upward in the figure by irradiation of the erasing light beam spot 4 on the part facing the N pole (that is, due to the optical energy of the light beam spot 4 and the external magnetic field 11) magnetization direction is reversed)
Unnecessary recorded information will be deleted.

On the other hand, since the magneto-optical disk 1 is still rotating in the six directions of the arrows, the position where the light beam spot 5 is irradiated is the part erased by the previous light beam spot 4. Therefore, when the light beam spot 5 is irradiated onto the portion, new information is recorded as a reversal of the magnetization direction in the same process as during erasing.

In this way, the direction of the external magnetic field 11 is different between the part irradiated with the light beam spot 4 and the part irradiated with the light beam spot 5. An external magnetic field 11 acts in the recording direction in the area where is irradiated, and by simultaneously using the unmodulated light beam spot 4 and the light beam spot 5 modulated according to the information, unnecessary information can be erased. It is possible to re-record new information almost simultaneously.

[Problems to be Solved by the Invention] However, in the conventional example shown in FIG.
, S are approximately 100 μm apart.

By the way, the spot diameter of a light beam spot in optical recording (reproduction) devices such as optical disks and magneto-optical disks is approximately 1 μm, and therefore the size of recording pits is 1 μm.
Moreover, the distance between adjacent signal rows in a recording pit, that is, the track pitch, is 2 μm or less. The substrate carrying a ferromagnetic thin film made of alloys such as Gd, Tb, and FC+ has eccentric track pitch unevenness, and at a position 100 μm away from the track circumference, the track pitch unevenness becomes quite noticeable. .

Therefore, even if one magnetic pole side is made to follow a track by a tracking servo using a push-pull method, it is difficult to maintain the spot position on the other magnetic pole side on the same track. ) may end up in adjacent tracks or other locations. It may be possible to solve the above problem by using a very high-precision optical system, a tracking control system, and a magneto-optical disk with less track pitch unevenness, but the drawback is that the cost will be extremely high. There is.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a magneto-optical recording/reproducing device that can perform erasing and recording while following a target track without requiring a highly accurate tracking control system. With the goal.

[Means and effects for solving the problem] In the present invention, in a magneto-optical recording/reproducing device that rewritably records or reproduces information data using magneto-optical effect, a coil of an external magnetic field applying means is applied in a recording mode. By forming a recording means that performs recording by applying a recording signal and controlling the emission intensity, it is possible to eliminate the need for erasing using an erasing mode.
In addition, recording can be performed without requiring any special tracking control means with high precision.

[Example] Hereinafter, the present invention will be specifically explained with reference to the drawings.

1 to 3 relate to one embodiment of the present invention, FIG. 1 shows the configuration of one embodiment, and FIG. 2 shows that each track of a magneto-optical disk is divided into a number of sectors. show,
FIG. 3 shows a sector memory that stores sector information data.

As shown in FIG.
1, an optical pickup 23 is mounted on a carriage as a movable base, facing one surface of a magneto-optical disk 22 as a disk-shaped recording medium which is rotationally driven by a spindle motor (not shown) (perpendicularly above or below the plane of the paper). 25, and a field coil 26 as an external magnetic field applying means is disposed facing the surface of the (magneto-optical) disk 22 on the opposite side from the optical pickup 23.

The disk 22 is mounted on a PC board 22a.

The recording film 22b is provided with a ferromagnetic thin film made of an alloy of Tb and Fe, and is placed on a turntable attached to the rotating shaft of a spindle motor, and is rotatably clamped by a clamp member lowered from above. It is intended to be done.

The carriage 25 is movable in the radial direction of the disk 22, or in the direction across the concentric or spiral tracks of the jammed disk 22 (in the direction perpendicular to the plane of the paper in FIG. 1) by a driving means such as a voice coil motor. carriage 25
The (optical) pickup 23 that is moved together with the
A laser diode 27 as a light source is attached to the pickup housing.

The light beam of the laser diode 27 is made into a parallel light beam by a collimator lens 28, and this parallel light beam is made into a linearly polarized light wave whose vibration plane is aligned in a certain direction by a polarizer 29, and this polarized light wave is divided into half. A part of the light beam passes through a mirror prism (beam splitter) 31, and is irradiated into a focused spot on the recording film 22b by an objective lens 32.

The objective lens 32 is configured to move the objective lens 32 minutely in a direction perpendicular to the tracks of the disk 22 (in other words, in a direction perpendicular to the plane of the paper) by passing a current through a tracking coil 34 forming the actuator 33 by an (objective lens) actuator 33. The light beam irradiated onto the disk 22 can be moved by moving within a range, and tracking control can be performed to follow the target track. Furthermore, by passing a current through the focus coil 35, the objective lens 32 can be moved within a minute range in the direction F perpendicular to the disk surface, and the focus can be controlled using this focus coil 35.

The light beam irradiated onto the recording film 22b is reflected and efficiently taken in by the objective lens 32, but the vibration plane of the returned light depends on the direction of magnetization with respect to the direction of the vibration plane in the past. and rotate by a small angle in opposite directions. A portion of the light taken in by the objective lens 32 is reflected by the beam splitter 31.
The light reflected by the beam splitter 37 is further transmitted to the second beam splitter 37.
is incident on the The light transmitted through this beam splitter 37 passes through an analyzer 38 and a condensing lens 39, and is received by a photodiode 40 as a photodetector, and the photoelectric conversion output produces a data reproduction signal SR of recorded information, which is amplified by an amplifier 41. and output.

On the other hand, the light reflected by the second beam splitter 37 passes through a cylindrical lens 42 and is received by a four-split photodetector 43. A pair of diagonal outputs from this four-division detector 43 (addition is made for each two detector elements along the diagonal direction) is outputted to a differential amplifier 44.
By applying this signal to the focus coil 35 via a phase compensation circuit and a drive circuit, the position (distance) of the objective lens 32 in the vertical direction to the disk surface is determined. This is so that the light beam irradiated onto the disk surface can be controlled and maintained in a focused state where it is focused into a spot.

Also, in the four-division detector 44 (of the disk)
A pair of detector element outputs divided into four parts in a plane parallel to the track (addition is made for outputs along the track direction).
is passed through the differential amplifier 45 to obtain a tracking error signal ST, and by applying this signal to the tracking coil 31 via a phase compensation circuit and a drive circuit, the light beam irradiated onto the disk 3 is accessed. This allows a tracking control state to be maintained to follow the track.

By the way, the field coil 26 has a coil 47 mounted on a plate-shaped ferromagnetic material 46, which has a length that covers the recording track width (in the direction perpendicular to the plane of the paper in FIG. 1), which is the part to which the light beam is irradiated. The coil 47 is formed by winding the coil 47 with a signal current corresponding to recording information (during the recording mode).

Note that each concentric track of the disk 22 is divided into a large number of sectors, and the division is divided into a pair of sectors so that recording can be performed in the recording mode without erasing in the erasing mode, as shown in FIG. Sectors Si, Si' (i=1
．． 2. ...) are divided by.

Also, as shown in FIG. 3, a pair of sectors 3t.

A pair of sector memories M are used to store recording bits for Si′.
sn and MSn' are provided, and a reproduced signal can be obtained by the output of these sector memories Msn and Msn' through an exclusive OR circuit EXOR.

The operation of one embodiment configured in this manner will be described below.

First, the operation in playback mode will be explained.

In this case, the field coil 26 is set to a non-operating state. Thus, the target track is accessed through a coarse search by moving the carriage 25 and a fine search by moving the objective lens 32, and the tracking servo means holds the track so as to follow it, and the focus servo means brings the target track into focus. is maintained.

The photodetector 40 of the pickup 23 reads out the data recorded in sector S1 81' of the target track, stores one sector's worth of data in sector S1 in the sector memory flash 51, and then reads out the data recorded in sector 81'. At the time when is read, both sectors $1 and 8 are read.
A reproduction signal of recorded information is obtained from the exclusive OR output of bits corresponding to the same address of 1'.

Next, the operation in recording mode will be explained.

First, assume that information has never been recorded or reproduced. Table 1 shows the progress of this process.

This table shows how the bit at the same bit position changes each time information is recorded.

In Table 1, the symbol T indicates the transition in which recording was performed, and the symbol W indicates the bit of recorded information at the test position of the bit in the tree table. Code B. ,B.

is 0N with recorded information by the optical system shown in Figure 1.
-OFF modulated sectors sn and sn't' are shown in the light emission state, 111 II is the light emission state, and 110 II is the erased state. Code M. 1M1 is field coil 2 in Figure 1.
The tip of the ferromagnetic material 46 of No. 6 is the sector Sn.

3 shows the magnetization direction at a timing opposite to n/.

In other words, the magnetization direction when the sector 3n of the disk 3 is irradiated with focused light is Mo, and the magnetization direction in the case of the sector S opening is M.
1, and in the table, 0.1 corresponds to the magnetization directions N and S.

Code P. , Pl are data reproduction signals read from sectors Sn and Sn', respectively. Further, symbol R indicates the above-mentioned data reproduction signal P. , Pl shows the exclusive OR output of Pl.

Now, the data reproduction signal P (output signal of the amplifier 41) read by the optical system on the first surface of the disc in an initial state where no recording is performed, that is, the initial disc. , Pl indicate 1.0, and therefore the reproduced signal indicated by R is 1. This initial state is indicated by the symbol T=O.

Next, when 0 in the data string is written to the recorded portion, the reproduced signal R must become O. In Table 1, Po and Pl are each set to O. Po when the code T is O, P when T is 1 for Pl. , Pl to O, the magnetic field and the irradiation light beams are controlled. Zunawara, the initial P.

(-1).

M as the magnetic field given to Pl (-〇). .

Ml is set to 0.1, and the laser diode 27 is M.

When =0, the light emission intensity is set. Note that the reversal of the magnetic field is controlled so that it is performed every time information is recorded in the same portion. Further, ON-OFF modulation of the write beam for recording information is performed as follows. First, in the case of writing O, the magnetic field MO, Ml is applied to the magnetic field (7) The writing beam B corresponds only to the o side of the state 0.1 or 1,0. ,
This is to irradiate either B1. Furthermore, when writing 1, the writing beams Bo and B1 are aimed in the same manner regardless of the states of the magnetic fields M and M1, and therefore information is recorded using the magnetic field M. Po and Pl are changed depending on the state of 1M1. In this way, by controlling the write beam against the contradictory magnetic fields that reverse each time recording is performed, the recording magnetization direction is controlled, and information is recorded by combining the recorded information, making it possible to omit the process of erasing the recorded information. It becomes possible to invert recorded information. Furthermore, Table 2 will be explained. In Table 2, it is considered that the reproduction signal R of the recorded information becomes O when the recorded information P and P1 are 1.1. In this case as well, Po and Pl at the time of initialization are 1.0. Assuming that R starts from 1, when recording information W-O at T=1, the applied magnetic field Mo9M1 is a reciprocal magnetic field e that starts from 0 and 1 and reverses each time recording is performed, respectively. Yes, but the second
In the case of the table, B in the second table for MO and Ml is the opposite of the case in the first table. , B1 is M. If 9M1 is 0.1, Bo
, B1 are controlled to be in a state of 0.1.

Therefore, recorded information P. , Pl become 1,1, and therefore the recorded information reproduction signal R becomes O. Further, when it is desired to record 1, write beams P and B1 are both irradiated as in Table 1, and R is set to 1.

In the above method, exclusive OR is performed to obtain R, but if 'C is considered in Table 1, OR may be used, and in Table 2, NAND may be used.

According to one embodiment that operates in this manner, it becomes unnecessary to erase data in erase mode every time data is rewritten, and information can be recorded in a short time. In addition, there is no need for extremely high-precision tracking control means;
Recording can be performed reliably on the accessed track.

In addition, in the above-mentioned first embodiment, the format of the information data on the disk 3 is changed (for example, like a fixed disk).
If you decide, you can write in real time.

In other words, when the next sector for recording is reached in the recording mode, the I i II, II Q of the intrusion data
The direction of the original current is made to correspond to the coil 47 according to II, and the output of the laser diode 27 is set to the emission intensity.

Recording is performed in this way. Further, in this case, the output of the amplifier 41 becomes the reproduction signal.

In order to set the field coil 26 close to the disk 22, a focus control means such as a lens actuator of the pickup 24 is provided, and the output of this focus control means causes the tip of the field coil 26 to be set close to the disk 22. It may also be held constant at a position close to the surface.

[Effects of the Invention] As described above, according to the present invention, information is recorded by controlling the direction of the external magnetic field in the external magnetic field applying means according to the recorded data, so that the You can record data without having to erase it in erase mode. Furthermore, information can be recorded on the accessed track without requiring particularly high-precision tracking control means.

[Brief explanation of drawings]

1 to 3 relate to one embodiment of the present invention, FIG. 1 is a configuration diagram showing the configuration of one embodiment, and FIG. 2 is an explanation showing how each track of a disk is divided into sectors. FIG. 3 is an explanatory diagram showing the sector upstream used in one embodiment, and FIG. 4 is an explanatory diagram showing the main part of the conventional example. 21... Magneto-optical recording and reproducing device 22... (Magneto-optical) disk 23... (Optical) pickup 25... Carriage 26... Field coil 27.
...Laser diode 32...Objective lens 46...Ferromagnetic material 47...
・Coil Figure 2 Figure 4

Claims (1)

[Scope of Claims] Information can be reproduced or rewritably recorded on a magneto-optical recording medium by condensing and irradiating a light beam from a light source using an optical pickup onto a magneto-optical recording medium. A magneto-optical recording and reproducing device capable of recording information, characterized in that information is recorded by applying a signal corresponding to recorded information to a coil of an external magnetic field applying means disposed opposite to the optical pickup. Magneto-optical recording and reproducing device.