JPS59140605A - Erasing system of photomagnetic recorder - Google Patents

Abstract

PURPOSE:To erase completely a recorded track with a tracing action by inverting the polarity of a recording auxiliary magnetic field and increasing the intensity of the magnetic field without changing the laser output obtained in a recording mode even at the time of an erasion. CONSTITUTION:An optical head 4 is set at a designated track by a command of a head access controller 7. Then the voltage or current value of a power supply 8 is set by the controller 7 in accordance with the position of a recording medium 1 in its radius direction. Thus a magnetic field psi of the corresponding intensity is generated from an auxiliary magnetic field generator. Under such conditions, the designated address is read out. At the same time, the output of the laser is set at the same level as that of a time of recording and lit up continuously. In addition, the polarity of magnetic field is inverted by means of changeover switches 9 and 10. The intensity of an auxiliary magnetic field which is used at the time of erasion at a prescribed track position is larger than the magnetic field used at said track position at the time of recording. At the same time, the power supply 8 and switches 9 and 10 are set by the controller 7 to set the polarities opposite to each other between said both magnetic fields.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a light (thermal) method for optically recording and reproducing information using a laser beam or the like on a recording medium provided with a perpendicular magnetic thin film.
The present invention relates to a method for erasing recorded tracks using a magnetic recording device.

BACKGROUND OF THE INVENTION Conventionally, the following method has been proposed for erasing recorded tracks on a recording medium using a magneto-optical recording device.

(4) During erasing, the optical beam power is made stronger than during recording so that no recorded tracks remain.

(B) Even the vortices near the recorded tracks are stable! Chi&%λ
By erasing from the top position, no recorded tracks remain unerased.

However, in the French law, the light beam source is a laser.
When using a diode, the laser output during normal recording is used close to its upper limit, so increasing the output significantly during erasing will shorten the life of the laser diode.

Therefore, if a laser diode with sufficient output power is used, the disadvantage arises that the device becomes expensive.

On the other hand, with regard to the -recorded track 2. method of erasing by overlapping two or more times, it is very difficult to control the tracing of recorded tracks in this way, and
There is a problem that a long erasing time is required0 9 Furthermore, a problem common to both the (A) method and the ω) method is that recording/reproduction is performed by rotating the disk at a constant angular velocity (C, A, V). In magneto-optical disks using the C, A, and V disk rotation methods, the optical energy density is significantly different between the outer and inner tracks of the disk, so when recording is performed to compensate for each. However, there is a problem in that even during erasing, recorded tracks must be erased from the outer circumference toward the inner circumference with further compensation.

Purpose The present invention eliminates the above-mentioned conventional drawbacks, and its purpose is to reverse the polarity of the recording auxiliary magnetic field and increase the magnetic field strength, without changing the laser output during recording even during erasing. An object of the present invention is to provide an erasing method for a magneto-optical recording device that allows a recorded track to be completely erased by one tracing.

Embodiment Generally, in magneto-optical recording, the area ΔS of a recording bit is related to the laser output I, the exposure time Δt, and the strength ψ of the auxiliary magnetic field, and the relational expression shown in the following equation (1) holds: 0 Δ5−IXΔtXψ (1) The present invention'ft
Applicable to C, A, and V disk rotation type magneto-optical recording devices T
When the laser power is constant in the first equation, the exposure time Δt, which changes at the recording medium position V, shall be controlled by the strength ψ of the auxiliary magnetic field, and furthermore, when erasing, It is assumed that the recorded ΔS is completely canceled by making the strength ψ of the auxiliary magnetic field stronger than that during recording.

FIG. 1 shows an example of the configuration of a magneto-optical recording device according to the present invention, where l is a recording medium book and 9% substrate/9% substrate/
A and its predecessor Atsushi N substrate/Magneto-optical thin film provided on A/B
It consists of Kuomoto~N substrate/A is glass material,
Further, as the magneto-optical thin film/B, for example, GaTbCoF
Use e. The recording medium %l is rotationally driven by a spindle motor 3.

The head is an optical head for recording/reproducing, and is an optical-magnetic thin film/
This is a motor that is disposed facing B and moves the magneto-optical thin film/B in the radial direction of the recording medium*/ indicated by the arrow as an optical disc. It also drives the auxiliary magnetic field generator! Source, RI and IO are polarity changeover switches.

In erasing mode (E), change the polarity selector switches 9 and 10 to the auxiliary magnetic field generator and switch to recording mode (6).
) to have the opposite magnetic polarity. If, for example, a DC coil is used as the auxiliary magnetic field generator S, the magnetic polarity can be easily reversed by switching the terminals and terminals of the electric terminal for the auxiliary magnetic field generator.

Furthermore, if, for example, a DC quadrature power source is used as the power source t, switching of the magnetic field strength ψ can be easily realized.

In the magneto-optical recording device having such a configuration, the operation in the erase mode will be explained. Here, it is assumed that the recording medium J/ is being rotated by the spindle motor 3 at a constant angular velocity.

First, in response to a command from the head access controller 7, the motor 6 is driven to set the optical head and the auxiliary magnetic field generator 3 to the commanded track position. At this time, the intensity of the light beam emitted by the optical head becomes equal to the intensity of tW in the reading mode, '! lS% It is only necessary to confirm that the track address at the current position matches the commanded erase track address. After the optical header is set at the specified track position in this way, it is set at a position in the radial direction of the recording medium %/. When the controller sets a corresponding voltage value or current value of the power source t, a magnetic field ψ of a corresponding strength is generated by the auxiliary magnetic field generator. In this state, the designated track address is read, and at the same time, the laser output is set to be equal to that during recording, and the laser is turned on continuously.

Furthermore, the above-mentioned magnetic field polarity reversal switching switch and one
Perform at 0. The controller 7 controls the power source g and the switches 9 and 10 so that the strength ψ of the auxiliary magnetic field used in the erase mode at a predetermined track position is stronger than the strength of the magnetic field used in the recording mode at that position and has the opposite polarity. Set.

In this way, by controlling the strength and polarity of the auxiliary magnetic field, the tracks on the optical recording medium can be reliably erased over the entire recording surface of the recording medium with the same laser power as during recording. .

Furthermore, as shown in FIG. 2, when setting the strength of the magnetic field of the auxiliary magnetic field generator 3 using the controller 7 and the power source,
In the erase mode, the same power supply voltage or current value as in the recording mode is set, and if the value is set to be higher in the erase mode, an erase bias power supply is provided, and the power supply voltage or current value in the recording mode is set to the same value in the erase mode. It may be added.

Effects As explained above, according to the present invention, when erasing a recorded track of an optical recording medium, the polarity of the auxiliary magnetic field is reversed, and the strength of the magnetic field is made higher than that in the recording mode. However, since the intensity is different from the outer circumference to the inner circumference in the radial direction of the recording medium, the recorded track can be completely erased with one trace. can get.

Note that auto-tracking can be performed almost unaffected by magnetic patterns caused by recording/erasing if the XIS recording medium is of a so-called pre-group type (grooved). Furthermore, autofocus can be similarly controlled almost independently of the magnetic pattern.

[Brief explanation of drawings]

FIG. 7 is a block diagram showing an example of the configuration of a magneto-optical recording device according to the present invention, and FIG. 1 is a block diagram showing the main parts of another example of the magneto-optical recording device according to the present invention. /... Recording medium cylinder, /A... Optical disk substrate, /B... Magneto-optical thin film, 3... Spindle motor, D... Optical head, S... Auxiliary magnetic field generator, 6 ···motor, ? , 10...switch, lco...bias power supply. Patent applicant Canon Co., Ltd.-2

Claims (1)

[Claims] In an erasing method of a magneto-optical recording device in which information is erased by rotating a recording medium on which information is magnetically recorded at a constant angular velocity and irradiating a light beam while applying a magnetic field to the recording medium, the recording medium An erasing method for a magneto-optical recording device, characterized in that the strength of the applied magnetic field is different between an inner circumferential portion and an outer circumferential portion.