JPS61276151A - Photoelectric recording method - Google Patents

Abstract

PURPOSE:To shorten the access time by starting the erasion of the recorded information before the recording start point after one circle to end it before the recording start point. CONSTITUTION:An erasing or recording magnetic field 3 or 4 is applied to a track 2 which is divided into sections by plural sectors 1 formed radially from the center of a disk. The recording start point (the 2st sector) 5 comes back for each rotation. Here the application of the field 3 is started at a time point preceding a recording start point 5 by a sector and finished at a time point preceding the point 5 by a sector. Thus, the magnetic field is inverted immediately. This inversion of the magnetic field is facilitated since the disk revolving speed is high although some time is needed for said inversion of the magnetic field.

Description

[Detailed Description of the Invention] [Summary] A recording method that enables recording immediately from the recording start point by ending the application of an erasing magnetic field before the recording start point when rerecording on a magneto-optical disk. .

[Industrial application field]

The present invention relates to a magneto-optical recording method capable of rapidly recording information.

A magneto-optical disk is a memory that uses laser light to record high-density information. Like an optical disk, it has a large storage capacity, can perform contactless recording and playback, and is unaffected by dust. It is a memory with unique characteristics.

In other words, the laser beam can be narrowed down to a small spot with a diameter of 1 μm or less using a lens.
The area required for recording bit information is approximately lμDI2.

Therefore, the area required for recording one bit of information on a magnetic disk or magnetic tape is much smaller than that of several tens to several hundreds of .mu.I@2, and therefore, large-capacity recording is possible.

In addition, when narrowing down with a lens, the beam diameter becomes about 1 inch wide on the substrate surface of the magneto-optical disk, so even if there is dust of several tens of microliters on the substrate surface, it will not be possible to record.
This can be done with almost no effect on playback.

Magneto-optical disks and optical disks that use laser light as a light source have excellent properties, but when comparing the two, optical disks use a low-melting point metal as a recording medium, and information is recorded and reproduced using holes (bits). ) Read only memory (Read 0nly Memo)
ry) is the main one and has already been put into practical use.

On the other hand, magneto-optical disks are rewritable memory (Eras)
This technology is currently being developed as a capable memory, in which magnetization reversal due to temperature rise of a magnetic film irradiated with a laser is used to record and erase information, and rotation of the polarization plane of reflected or transmitted light from the magnetic film is used to record and erase information. It is used for continuous light production.

[Conventional technology]

As mentioned earlier, magneto-optical disks (hereinafter simply referred to as disks) are made by irradiating a perpendicularly magnetized film, which is a recording medium, with a laser beam focused to a diameter of 1 μm or less under the application of a magnetic field. It is heated to a temperature close to or above the Curie temperature, and the perpendicular magnetization of the irradiated area is oriented in the direction of the magnetic field due to a decrease in coercive force, which is used for recording and erasing. be.

Here, the direction of the magnetic field is opposite between recording and erasing, but the problem is that it takes several microseconds to change the direction of the magnetic field.

In other words, an electromagnet with a rectangular cross section is used to apply the magnetic field, giving a magnetic field perpendicular to the disk surface, but the disk continues to rotate even when the magnetic field is reversed by switching the coil current. Therefore, when attempting to erase already recorded information and immediately start recording, the recorded information during the reversal of the magnetic field will not be recorded.

For example, when erasing one track on a disc and recording information on this track, the recording start point (lomePosit
ion) up to the recording start point, and then immediately writing from the recording start point, this is impossible because it takes time to reverse the magnetic field, so it was done after waiting for the disk to rotate once.

The number of disks varies depending on the model, and is between 1000 and 300.
Although it rotates at a speed of 0 Rr'H, the waiting time for one rotation is necessary for access, which is a problem when processing information at high speed.

[Problem that the invention seeks to solve]

As described above, when erasing and recording information quickly, magneto-optical disks require time to reverse the magnetic field, and therefore the access time cannot be shortened, which is a problem.

[Means for solving problems]

The above problem arises in magneto-optical disks that use a single laser beam to erase and record information.Erasing previously recorded information begins before the recording start point, and after a single revolution, before the recording start point. This problem can be solved by a magneto-optical recording method characterized by performing magnetic field reversal and recording from the recording start point.

[Effect]

Since it takes time to reverse the magnetic field, the present invention has changed the conventional method of erasing from the recording start point, ending at the recording start point, reversing the magnetic field, and writing from the next recording start point. By finishing the operation before the recording start point, it is possible to record from the recording start point.

That is, the access time can be reduced by shifting the erase start point and write start point by a time sufficient for magnetic field reversal to occur.

〔Example〕

As a method for explaining the present invention, the figure shows a developed track 2 divided by a plurality of sectors l formed radially from the center of the disk, and an erase magnetic field 3 and a recording magnetic field 4 applied thereto. This indicates the timing.

In other words, the recording start point (first sector) 5 rotates with each rotation, but in the present invention, the application of the erase magnetic field 3 starts one sector before the recording start point 5 and ends one sector before the recording start point. and immediately perform magnetic field reversal.

This magnetic field reversal takes several microseconds, but even if the disk rotational speed is 300 ORPM, the passage time from one sector to the next sector is several tens of meters, so the magnetic field reversal is complete and the recording start point 5 A sufficient recording magnetic field 4 is applied at the stage of passing through.

In this way, in this embodiment, by applying the erasing magnetic field 3 one sector in advance, it is no longer necessary to wait for one revolution of the track to record information as in the conventional technique.

〔Effect of the invention〕

As described above, by delaying the application of the erasing magnetic field by the time required for magnetic field reversal and ending it faster than the recording start time of the disk, it is possible to immediately record after erasing information, which reduces the access time. can be shortened.

[Brief explanation of drawings]

The figure is a detailed explanatory diagram of the present invention. In the figure, 1 is a sector, 2 is a track, 3 is an erase magnetic field, 4 is a recording magnetic field, and 5 is a recording start point.

Claims (1)

[Claims] In a magneto-optical disk that erases and records information using a single laser beam, the erasure of previously recorded information begins before the recording start point and ends before the recording start point after the rotation, and the magnetic field is reversed. 1. A magneto-optical recording method characterized in that immediately after recording, recording is performed from a recording start point.