JPS61187139A - Optical information recording method - Google Patents

Abstract

PURPOSE:To record information of high density in a recording medium having no groove by providing a guide track consisting of parts changed to the second state in a recording medium of the first state, scanning on it by a light beam modulated according to light information and forming record bit changed to the first state. CONSTITUTION:An address signal bit 21 corresponding to an address signal is recorded in an address area 20 of a magnetic film 111 by an optical magnetic head used exclusively for recording by inverting the direction of magnetization downward while feeding an optical magnetic disk magnetized uniformly in upward direction on the track face by a feeding device. A linear record bit 23 is recorded similarly in the data area 22. When recording information, the record bit 23 also serves as a guide track. In recording information, the direction of magnetization of the record bit 23 is inverted to upward direction according to information and information record bit 24 is prepared.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an information recording method using optical means, and more specifically to an optical information recording method that can record information signals on a recording medium using a light beam. This invention relates to a recording method of a device.

[Conventional technology]

The above-mentioned optical information recording device is generally called a magneto-optical recording device, and the recording medium of the recording device is a disk made by sputtering a circular magnetic material such as glass. . To record information to this,
The recording medium is magnetized in one direction in advance by applying a perpendicular magnetic field, for example, and then a light beam (generally a radar beam) corresponding to the information signal is irradiated. Recording is performed by raising the temperature of the magnetic material to a temperature higher than the magnetic transition temperature (the Curie point) and reversing the magnetization of the region. This disk is rotated at a predetermined speed by a motor, and information signals are recorded on the disk in a spiral or concentric pattern by controlling the position of the light beam irradiated onto the disk.

In reproducing the recorded information, the magnetic Karr effect is used, in which when the disc is irradiated with a reproducing light beam, the direction of the reflected light of the reproducing light beam changes depending on the direction of the magnetic field. information can be detected and read.

During recording, a signal is given to a laser light beam generator based on information, and the oscillated light beam is generally a frequency modulated (FM) light beam or a digital signal modulated light beam. An example of recording using an FM light beam is shown in FIG. In the same figure, a frequency-modulated information signal is input to the optical beam generator. Figures (b) and (c) show the state of recording bits on the recording medium recorded based on the information signal, where (b) is a plan view and (C) is the magnetization seen from the cross-sectional direction. It shows the direction.

At this time, the recorded bits on the disk are arranged as shown in FIG. This aspect is very similar to that of a so-called optical disk device, but the greatest feature of a magneto-optical recording device is that it can be rewritten.

When rewriting, only unnecessary recording bits on the disk are erased and new information is recorded.

However, accurate tracking of the illuminating light beam is required to erase and rewrite only a portion of the recorded bits.

Tracking is generally performed in a reading device that detects illumination light.

One of the tracking methods is to provide a tracking guide groove track on the surface of a recording medium, and record, reproduce, and erase information along this groove track.

The width of this groove track is about 0.5 to 1 μm, and the depth is set to 1/8 wavelength of the light beam.
28X H・-N.

When using radar, the depth of the groove is approximately 0.085μ.
It becomes tnK. To detect the tracking error signal, a two-split photodetector is used, and their differential output is used as the tracking error signal.

FIG. 6 is a diagram schematically showing the distribution of the amount of reflected light received by the photodetector when the light beam spot crosses the groove track.

In FIG. 6, 1 is a recording medium, 2 is a groove track, and 3 is a light beam. Further, 4 indicates the light intensity distribution of the light received by the left photodetector among the reflected light of the light beam 3 irradiated onto the recording medium 1, and 5 indicates the light intensity distribution of the light received by the right photodetector. It is something that

As shown in FIG. 6(b), the center of the light beam 3 is located on the groove track 2.
If it coincides with the center of the light beam 3, the outputs of the two photodetectors will be equal and the irradiation position of the light beam 3 will not change. However, when the light beam 3 is irradiated onto the end of the groove track 2 (as shown in FIGS. 6(,) and (c)), the depth of the groove track 2 is 1/8 wavelength, so the groove track 2 is The two-way emitted light from a portion other than the groove track 2 causes interference, and the outputs of the two photodetectors are no longer equal. For example, when the left side of the groove track 2 is irradiated with the light beam 3 as shown in FIG. 6(a), the output of the right photodetector is larger than the output of the left photodetector. Due to the differential movement, the light beam 3 moves to the right.

By using the above tracking method, the light beam can accurately track the recorded bits. 1 more
Book light beam recording and playback.

Since the information can be erased, the number of optical components can be reduced, and the optical system can be adjusted relatively easily.

[Problem that the invention seeks to solve]

However, magneto-optical recording devices that use the above-mentioned tracking method require minute unevenness and glossy turns on the recording medium, which has the disadvantage of requiring more manufacturing steps than non-grooved disks, resulting in a significant increase in costs. .

On the other hand, when a disk without groove tracks is used, there is a drawback that cyclotalk is easily caused by external vibrations because there is no object to be tracked during recording. For discs without groove tracks, there is a method of separately providing recording bits exclusively for tracking, but this method has the disadvantage that the track pitch cannot be narrowed due to the recording bits, making it difficult to achieve high density. was there.

[Means for solving problems]

According to the present invention, in order to solve the above-mentioned problems, there is provided a method for recording information on a recording medium that reversibly changes into an optically distinguishable first or second state by irradiation with a light beam. In this method, an ID track is provided on the recording medium in the first state, which is made up of a portion that has changed to the second state in advance, and the ID track is scanned with a light beam modulated according to the recorded information. An information recording method is provided that is characterized by forming recording pits that have changed to a state of 1.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic diagram showing an example of an optical information recording device using the information recording method of the present invention.

Although the present invention is not limited to the case where it is applied to a magneto-optical recording device, for the sake of simplicity, in the following description, the case where it is applied to a magneto-optical recording device will be taken as an example.

In FIG. 1, the radar light generated from the semiconductor radar 6 is turned into parallel light by the collimator lens 7, and is converted into parallel light by the polarizer 8.
, passes through a beam splitter 9, and focuses a beam spot on a magneto-optical disk 11 by an objective lens 10.

The light reflected from the magneto-optical disk 11 passes through the objective lens 10 again, is reflected by the multilayer film 6 on the diagonal of the beam splitter 9, passes through the analyzer 12, and is sent to the optical sensor 14 by the sensor lens 131C. focused on the top.

This optical sensor 14 is operated in conjunction with a differential amplifier 15.
Signals of focus deviation and tracking deviation are obtained by a known method, and autofocus or autotracking is performed by a tracking actuator 16 provided in the objective lens 10. The magneto-optical disk 11 is placed on a turntable 17 that rotates with little vibration, and the table 17 is rotated by a high-precision motor 18.

To record information, the recording portion of the magneto-optical disk 11 is heated to more than one Curie point using radar light, and the recording is performed by the auxiliary magnetic field generator 19 provided close to the disk 11, as described in the section on the prior art. This is done by reversing the magnetization of the region.

FIG. 2 shows the information recording method of the present invention, and schematically shows the state of magnetization in a cross section of the magneto-optical disk 11 along the track to be recorded.

In FIG. 2, 11 indicates a magneto-optical disk, 111 is a magnetic film of the disk 11, and 112 is a substrate.

The magneto-optical disk in the embodiment of the present invention is magnetized uniformly in an upward direction in advance, and at the time of shipment, while the track surface is being fed by a feeding device with extremely little speed variation, an optical magnetic disk dedicated for recording is used. According to Fig. 2(a)
As shown in K, address signal recording pits 21 corresponding to the address signal are recorded in the address area 20 by reversing the magnetization direction downward, and in the data area 22, the magnetization direction is reversed. Line-shaped recording pits 23 are recorded by continuously reversing it downward.

The linear recording pits 23 are magnetized in the opposite direction to the magnetization direction on the recording medium that has been magnetized in advance, so when recording information, the linear recording bits 23 also serve as a guide track. (That is, the two-in-shaped recording pits 23) can be easily tracked.

When recording information using the optical information recording method of the present invention, as shown in FIG. Recording can be performed by reversing the direction and creating information signal recording pits 24.

In addition, when erasing information recorded as described above, the direction of magnetization on the linear recording pits 23 is uniformly aligned downward while the direction of the external magnetic field is reversed. Perform deletion.

FIG. 3 shows the information recording method of the present invention explained in FIG. 2 as seen from above the magneto-optical disk 11, and FIG. 3(a) shows the guide track formation shown in FIG. 2(&). FIG. 3(b) shows the state of the bit string after information recording. In FIG. 3, the recording pits in the shaded areas have a downward magnetization direction, and the white areas have an upward magnetization direction. Further, 25 is a track on the magneto-optical disk 11.

Note that in the present invention, the way signals in the address area and the signals in the data area are read are opposite, but this can be easily solved by reading the signals in the data area through an inverting circuit. , so there is no problem.

The present invention is not limited to the embodiments described above, and various embodiments are possible.

In other words, in the above embodiment, a magneto-optical disk device is used as an example of a recording device having two optically distinguishable states, but if the difference in magnetization direction is replaced with a crystallized state and an amorphous state, a phase transition can be realized. The information recording method of the present invention can of course be applied to optical disc devices of the above-mentioned method, and can be implemented in any other device that records information on a recording medium that reversibly changes into two optically distinguishable states. That is clear.

〔Effect of the invention〕

As described above in detail, according to the information recording method of the present invention, a grooveless optical information recording medium that is low in manufacturing cost,
It became possible to record high-density information.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a magneto-optical recording device capable of implementing the optical information recording method of the present invention. Figure 2 is a diagram showing the optical information recording method of the present invention)
, FIG. 3 is a diagram showing the appearance of recording pits on a track. FIG. 4 is a schematic diagram showing an example of recording on a magneto-optical recording medium using a 7M light beam, and FIG. 5 is a diagram showing the appearance of recording pits on a magneto-optical recording disk. FIG. 6 is a schematic diagram showing an example of a method of tracking an irradiated light beam. DESCRIPTION OF SYMBOLS 11... Magneto-optical disk, 21... Address signal recording pit, 23... Line-shaped recording pit, 24...
Information signal recording pit. Agent Patent Attorney Seki Yamashita Hirabe Figure 1 Figure 2 (b) 22 Teichida Shinkyo Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] In a method for recording information on a recording medium that reversibly changes into an optically distinguishable first or second state by irradiation with a light beam, the recording medium in the first state is changed into the second state in advance. 1. An information recording method, comprising: providing a guide track consisting of a plurality of sections, and scanning the guide track with a light beam modulated according to recorded information to form recording pits changed to a first state.