JPS6254857A - Photo-magnetic information recorder - Google Patents

Abstract

PURPOSE:To easily detect whether or not the recording is normal by so constituting the titled recorder that an optical beam is separated in two optical fluxes, the fluxes are made to transmit two analysers of different azimuth angles of axis of transmission, and the abnormality of the recording is detected by a difference signal obtained between the transmission-quantity of said two fluxes. CONSTITUTION:A reflecting light from a recording medium 4 is reflected by a polarizing beam splitter 5, and is halved by a half mirror 12. The analysers 6 and 13 are so disposed that their azimuth angles of axis of transmission respectively form 45 degrees, in opposite directions, with the plane of polarization of the reflecting light from a disc having no photo-magnetic effect when it is placed on the surface of the recording medium as a pseudo-disc. Amplifiers 9 and 16 respectively amplify the outputs from the analysers 8 and 15. A differential amplifier 17 obtains the difference signal from between the outputs from the amplifiers 9 and 16. A comparator 18 makes the output from the differential amplifier 17 to be a digital signal,while a delay circuit 19 delays a laser modulating signal S1 by a time To. A sampling circuit 20 samples the output from the comparator 18 at the rising of the output of the circuit 19.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical information recording/reproducing device, and more specifically, the present invention relates to an optical information recording/reproducing device, and more specifically, it is possible to determine whether or not normal recording is being performed at the time of recording without using means such as multi-beams. The present invention relates to a magneto-optical information recording device having a function of determining.

[Conventional technology]

A typical example of the above-mentioned optical information recording/reproducing apparatus is a magneto-optical information recording/reproducing apparatus using a disk-shaped recording medium having a magnetic film. FIG. 5 is a schematic configuration diagram showing a conventional magneto-optical information recording/reproducing apparatus. To record information, first, a laser beam modulated by the recording information signal S1 in the laser drive circuit 10 is emitted from the semiconductor radar 1. The laser beam is converted into parallel light by a collimator lens 2, passes through a polarizing beam splitter 5, and is formed into a light spot on a disk-shaped recording medium 4 by an objective lens 3. The recording portion of the recording medium 4 is uniformly magnetized in one direction in advance. When a portion of the recording medium 4 that has been heated above the Sciuris point by the light beam is cooled, it is magnetized by the magnetic field of the bias magnet 11 in a direction opposite to the direction in which it was previously magnetized. In this way, the information is recorded on the recording medium 4.
is recorded in the magnetic film as a reversal of magnetization.

Whether or not information has been properly recorded is confirmed by playback, and various methods have been considered for this confirmation. For example, one method is to reproduce the recorded portion after one rotation of the disk when the recording medium 4 is disk-shaped.

In general, reproduction is carried out by continuously emitting laser 1 at a lower intensity than recording, irradiating the recorded area with the light beam, and detecting the polarization direction due to the difference in the magnetization direction of the reflected light. In the reproduction shown in FIG. 5, the reflected light from the recording medium 4 is reflected by the polarizing beam splitter 5, the component whose polarization plane has changed is guided to the analyzer 6, and the light that has passed through the analyzer 6 is directed to the condenser lens 7. This is done by guiding the light to the optical analyzer 8. The output of the analyzer 8 is outputted to the amplifier 9 as a reproduced signal S2. By recording the signal S1 applied during recording in a memory and comparing it with the reproduced signal S2 after one rotation of the disk, it is possible to judge whether accurate recording has been made. Another method is to place the playback beam at a position slightly behind the recording beam, obtain the playback signal S2 without waiting for one revolution of the disk, and set the recording signal S1 at the interval between the recording beam and the playback beam. There is also a method of delaying the signal by a certain amount of time and comparing it with the reproduced signal S2.

[Problem that the invention seeks to solve]

However, in the former method, it is necessary to wait for the disk to rotate before information can be confirmed, and in the latter method, means for generating multiple beams and means for detecting them are required, resulting in a complicated optical system. was there.

[Means for solving problems]

The present invention has been made in view of the problems of the prior art as described above, and a magneto-optical information recording device of the present invention is a magneto-optical information recording device that records information by irradiating a light beam onto a magnetic recording medium. means for dividing the reflected light when the medium is irradiated with the light beam into two light beams; and means for passing the divided light beams through two analyzers having different transmission axis azimuths and detecting the amount of light passing therethrough. and means for detecting a recording abnormality from a difference signal between the signals detected from each of the light beams.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the magneto-optical information recording device of this invention will be explained in detail based on an Example.

FIG. 1 shows a schematic configuration diagram of a magneto-optical information recording device (hereinafter referred to as the device) of the present invention. Components that are the same as the fifth one are represented by the same numbers. In FIG. 1, reflected light from a recording medium 4 is reflected by a polarizing beam splitter 5, and divided into two by a half mirror 12. 13, 14.15 are the same as 6, 7.8, respectively, and are an analyzer, a focusing lens, and an analyzer. Analyzer 6.13 has its transmission axis azimuth 45 degrees in the opposite direction to the polarization plane of light reflected from the disk when a disk without magneto-optical effect is placed on the surface of the recording medium. ' are arranged to form an angle. Reference numerals 9 and 16 are amplifiers that amplify the outputs of the analyzers 8 and 150, respectively, and 17 is a differential amplifier that obtains a signal representing the difference between the outputs of the amplifiers 9 and 16. 18 is a comparator that converts the output of the differential amplifier 17 into a digital signal. 19 is a delay circuit that delays the laser modulation signal S1 by a time 'ro, and 20 is a sampling circuit that samples the output of the comparator 18 at the rising edge of the output of the delay circuit 19.

Next, the principle of detecting recording abnormalities in the device of the present invention will be explained in the second section.
This will be explained according to FIGS.

FIG. 2 shows the appearance of pits on a recording medium when a magnetization pattern as shown in FIG. 2 (2) is formed using a Norse signal as shown in FIG. 2 (1). Here, it is assumed that recording is performed at 5 MHz with a radius of 70 m and a speed of 1800 rpm. In Figure 2, the unmarked region A is a region that has the direction of magnetization at the time of initialization, and the dotted region B is a region that has been heated by radar light to a temperature above one Curie and has a clear vertical direction. This is a region that has no direction of magnetization. A diagonally shaded area C in the lower right corner is an area where a recording magnetization pattern is formed, and is magnetized in the opposite direction to area A. The area of the upper right blade is the area irradiated with the recording laser beam.

Formation of the fourth turn of recording is started by turning on the laser at time t1. The time constant of the heat rise of the recording medium is about 10 n5 ec, and the length that the recording medium moves during this time is about 10% of the forming/leaning time and will be ignored in this explanation. At time t1, the temperature of the medium rises, and as shown in FIG. 2(3), the temperature of the area B in the center of the area irradiated with light, which is the area indicated by the diagonal lines in the upper right, rises to a temperature of one Curie point or more. At time t2, as shown in FIG. 2 (4), there is an area C (lower right corner i!) where the light beam passes and the recording pattern is formed, and just before the laser disappears at time t5, Figure 2 (5)
It will look like this.

FIG. 3 shows the polarization of reflected light obtained from each region. The polarization plane of the light incident on the recording medium is set in the OB direction, the polarization plane of the analyzer 6 is arranged in the oc' direction, and the polarization plane of the analyzer 13 is arranged in the OA' direction. Due to the Kerr effect, the plane of polarization of the reflected light from each area of the recording medium changes, and the output from the analyzer 8 is that the reflected light from area A is a signal corresponding to OA', and the reflected light from area B is a signal corresponding to OA'. The light becomes a signal corresponding to OB', and the reflected light from area C becomes a signal corresponding to oc'.

The output from the analyzer 15 is OA' for areas A, B, and C, respectively.

OB', QC".

Next, a method for determining whether recording has been performed normally according to the present invention will be explained.

If the recording is performed normally, the output from the analyzer 8 will be as shown in Fig. 4(a)-(1), and the output from the analyzer 15 will be as shown in Fig. 4(a)-(a). It becomes as shown in (2).

At time t1 when the lighting of the recording light starts, the area C
However, at time t3, area C is formed and signals corresponding to OA' and OA' are obtained.
Since reflected light from this part is also included, oc', o
A signal corresponding to c' is also obtained.

However, if recording is not performed normally, if area C is not formed due to a tamper, out of focus, or defect in the disk medium, the outputs from the analyzers 8 and 15 will be as shown in FIG. 4 (b), respectively. The results are as shown in (1) and (2). Most of the light is reflected from area A, but since the temperature is raised to a certain extent, reflected light from an intermediate area between areas A and B is obtained. The difference in reflected light when recording is performed normally and when it is not is shown in (a)-- in Figure 4, respectively.
(3) and (b)-(3). However, the amplifiers 9 and 16 do not pass high frequencies higher than necessary, nor do they pass DC components. Therefore, the outputs of the differential amplifier 17 become as shown in FIGS. 4(a)-(4) and (b)-(4), respectively. If these are binarized by the comparator 18, the output from the comparator 18 will be Fig. 4B) - (5)
, as shown in (b)-(5). If the output of the controller 18 is sampled by the sampling circuit 20 after the time To has elapsed from the start-up of the radar 1, the result will be as shown in Fig. 4(a)-(5) if the recording is performed normally.
), the sampling output will be 11", and if recording is not performed normally, the output will be "11" in Figure 4 (B)-(5).
0'', it is possible to determine a recording abnormality.

In the above embodiment, the phase shift is detected as tl-1-'r,)
I am sampling the playback signal output at the time of .

The present invention is not limited to this, and a method such as counting the shift in start-up time can also be used.

〔Effect of the invention〕

As described above, according to the magneto-optical information recording device of the present invention, it is possible to determine whether a recording pattern has been formed almost simultaneously with recording, and whether recording is normal or not, using a simple optical system using one recording beam. It is easy to detect whether it is present or not.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a magneto-optical information recording apparatus of the present invention. FIG. 2 is a diagram showing the process of forming magnetized arm turns on a recording medium by irradiation with a light beam. FIGS. 3 and 4 are diagrams for explaining a method for determining whether recording has been performed normally. FIG. 5 is a schematic diagram of a conventional magneto-optical information recording/reproducing apparatus. Agent Patent Attorney Jo Yamashita Hei 4 (A) (B)

Claims (1)

[Claims] (1) A magneto-optical information recording device that records information by irradiating a light beam onto a magnetic recording medium, comprising means for dividing reflected light when the medium is irradiated with the light beam into two beams; A means for passing the light beam through two analyzers having different transmission axis azimuths and detecting the amount of light passing therethrough, and a means for detecting a recording abnormality from a difference signal between signals detected from each of the light beams. A magneto-optical information recording device characterized by: