JPS61276149A - Photomagnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To perform quickly the recording and its confirmation by leading the reflected light produced when a recording beam is irradiated on a medium to a binary coding circuit and then to a sampling circuit from a differential amplifier through an analyzer. CONSTITUTION:The reflected light produced when a recording beam is irradiated on a medium 4 is led to a binary coding circuit 14 through an analyzer 6 and a differential amplifying circuit 12. A waveform shown in the figure is delivered to the circuit 14. Then a sampling circuit 15 samples a binary coded signal at a time point T4 when the delay time t0 passed from the lighting start of a semiconductor laser 1. Here it is known from the output '1' that the recording is carried out normally. While another waveform shown in the figure emerges at the output of the circuit 12 if the recording is not normal. Then the circuit 15 outputs the signal '0' at the time point T4. Thus, it is recognized from the signal '0' that the present recording is not normal.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magneto-optical recording and reproducing device.

[Prior Art] An example of a conventional magneto-optical information recording/reproducing device is shown in FIG. 5. In this conventional example, the recording portion of the medium is magnetized in a uniform direction before recording. Then, a predetermined recording information signal 51 is modulated by the laser drive circuit 10, and the semiconductor laser l emits a light beam based on this modulation signal.

The light from the laser I becomes parallel light by the collimator lens 2, passes through the polarizing beam splitter 5, and forms a light spot on the perpendicularly magnetized medium 4 by the objective lens 3.

When the portion of the medium 4 that has been heated to a Curie temperature or higher by the light beam is cooled, it is magnetized in a predetermined direction by the magnetic field of the bias magnet 11a. This predetermined direction is a direction opposite to the direction in which the bias magnet 11a is magnetized in advance. By this magnetization, predetermined information is recorded on the medium 4.

Here, whether or not the above-mentioned recording has been performed normally is confirmed by reproducing the above-mentioned recorded portion in a primary manner.

First, if the recording strip 4 is on a disk, the medium 4
After recording information for one revolution of , on the medium 4, reproducing the recorded information for one revolution. A light spot is irradiated onto the medium 4 along the same route.

Here, the reflected light from the medium 4 of the perpendicularly magnetized film is:

The plane of polarization differs depending on the magnetization direction of the recording site. By reflecting the reflected light from the medium 4 by the polarizing beam splitter 5, the proportion of the component changed in the polarization plane of the l2 reflected light is increased (in other words, the proportion of the component whose polarization plane has been rotated is increased). (after increasing the height), the light is analyzed by analyzer 6.
The light that has passed through the analyzer 6 is guided to the analyzer 8 by the condensing lens 7.The output of the analyzer 8 is amplified by the amplifier 9, and this output signal is converted into the reproduced signal S.
It becomes 2.

Then, the recording signal Sl given during recording is stored in a predetermined memory in advance, and after the medium 4 is rotated once for reproduction, the reproduction signal S2 and the recording signal Sl are compared. Based on this, it is determined whether or not normal recording has been made. That is, if both signals Sl and 52 are the same, it means that normal recording has been performed.

However, in the above conventional technology, after the medium 4 rotates once for recording, it is necessary to wait for the medium 4 to rotate once again before confirming that the recording is normal. In this way, since it is necessary to repeat recording and reproduction every time the disk rotates, there is a problem that the overall recording time becomes twice as long.

As another recording confirmation device, there is a device that places another beam (reproducing beam) at a position slightly behind the recording beam. This device obtains the reproduced signal S2 without waiting for one revolution of the medium 4. Then, for a time corresponding to the interval between the recording and reproduction two beams, the recording signal S1 is
Delay this ia! The recorded signal Sl and the reproduced signal S2 are compared, thereby confirming normal recording.

Since this device requires means for generating multiple beams and means for detecting multiple beams,
There is a problem that the optical system becomes complicated.

[Object of the Invention] The present invention has been made by paying attention to the problems of the prior art described above, and records and confirms the same using one beam, and almost simultaneously with the recording.

It is an object of the present invention to provide a magneto-optical recording/reproducing device that can confirm the recording.

[Embodiments of the invention] FIG. 1 is a block diagram showing one embodiment of the present invention.

Incidentally, the same members as those in the conventional example shown in FIG. 5 are given the same reference numerals, and the explanation thereof will be omitted.

The waveform shaping circuit 11 is a circuit that shapes the recording signal SIK into a reference rectangular wave having a predetermined amplitude based on the recording signal SIK. The reference rectangular wave will be described later. The differential amplifier circuit 12 is a circuit that outputs the difference between the output of the amplifier 9 and the output of the shaping circuit 11, and the delay circuit 13 is a circuit that delays the recording signal SL by a time to.

The binarization circuit 14 is a circuit that binarizes the output of the differential amplifier circuit 12, and the sampling circuit 15 is a circuit that binarizes the output of the differential amplifier circuit 12.
This circuit samples the output of the binarization circuit 14 when the output signal rises.

FIG. 2 is an explanatory diagram of magneto-optical recording.

FIG. 2(1) is a diagram showing the waveform of the recording laser beam, in which the semiconductor laser 1 starts lighting at TI and turns off at T3.

FIG. 2 (2) is a diagram showing a magnetization pattern recorded on the medium 4. In this case, the radius of the disk-shaped medium 4 is 70.
Let us take as an example the case where the medium 4 is rotated at 1,800 rp and recorded using a 5 MI (z signal) using a rotary section.

In addition, (3) in the same figure shows the start of lighting of the semiconductor laser l (T
1) is a diagram showing the state on the medium 4 in FIG. Note that the unmarked region A is a region that is magnetized in the magnetization direction at the time of initialization, and the region B represented by a dot is a region that is not magnetized in a clear perpendicular magnetization direction (a region with a temperature higher than one Curie temperature). )
The area C indicated by the diagonal line downward to the right is the area where the recording magnetization pattern is formed (the area magnetized in the opposite magnetization direction to that at the time of initialization), and the area C indicated by the diagonal line downward to the left is It shows the area irradiated with the recording laser beam.

Note that the time constant of the heat rise of the recording medium 4 is approximately 10n! 1e
C, and the length that the medium 4 moves within this time is:
This is about 10% of the formed pattern. Therefore, in the following description, the amount of movement within the time required for the heat increase will be ignored.

FIG. 3 is an explanatory diagram of reflected light obtained from each region shown in FIG. 2.

Here, the polarization plane of the incident light is assumed to be the direction of OB.

And 1 reflected light is in the direction of OA'B'C' (polarization direction)
The reflected light from area A becomes the polarization plane (polarization direction) of OA due to the Kerr effect, and the reflected light from area C becomes the polarization plane (polarization direction) of OA. The light has a polarization plane of OC, and the reflected light from the region B whose magnetization direction is not determined has a polarization plane of OB, which is the same polarization plane as the incident light.

The amplitudes of the OA, QC, and OB force direction lights after passing through the analyzer 6 are OA', QC', and OB', respectively.

Here, if recording is performed normally.

The detection light that has passed through the analyzer 6 at time T1 is in the area A
The detection light obtained at time T2 and time T3 includes light from area C as well as areas A and H. The amplitude of the reflected light in this state is shown in No. 411 (1). In addition, in Fig. 4,
a', b', and C' indicate the amplitude of the light reflected from areas A, B, and C after passing through the analyzer 6, respectively.

FIG. 4(2) is a diagram showing the waveform of the reflected light that has passed through the analyzer 6 in the case where normal recording is not performed. In this case, during recording, the optical power sufficient to raise the temperature of the medium 4 above one Curie temperature is not applied to the medium 4, so that the amplitude of the reflected light passing through the analyzer 6 is lower than that when recording is performed normally. Although the amplitude is small, it is larger than the amplitude of the reflected light from area A alone. Furthermore, in the case of (2) in the same figure, since Ok is small to increase the temperature, it is slightly larger than the amplitude of the reflected light from area A only.

FIG. 4(3) shows the reference rectangular wave (waveform shaping circuit t
The peak value b' of this reference rectangular wave is set to a value approximately halfway between the peak value in FIG. 4(1) and the peak value in FIG. 4(2). The level of this reference square wave becomes a kind of threshold level in the above embodiment.

When the reproduced signal S2 is obtained during actual recording, the differential amplifier circuit 12 outputs a signal having the waveform shown in FIG. 4 (4) or the waveform shown in FIG. 4 (6).

Figure (4) shows the output of the differential amplifier circuit 12 when recording is performed normally, and is the waveform obtained by subtracting the signal shown in Figure (2) from the signal shown in Figure (1). be.

In this case, the waveform shown in FIG. The signal is sampled.

That is, in this case, a signal of "1" is output, and it can be recognized based on this rlJ that recording has been performed normally.

On the other hand, if the recording is abnormal, a waveform shown in FIG. 6 (6) appears at the output of the differential amplifier circuit 12. Then, the binarization circuit 14 outputs a signal shown in (7) of the same figure. Then, at T4, the sampling circuit 15
Outputs the J signal. Therefore, based on this "0" signal, it can be recognized that the current record is abnormal.

Note that when receiving reflected light from an area on the medium 4 where the @ sign is not recorded, the delay circuit 13 does not generate an output signal, so in that case, sampling by the sampling circuit 15 is not performed. Not possible.

Alternatively, the area C may be recorded as an initial state instead of the area A, and the recorded pattern may become the area A. In this case, the amount of reflected light from the recorded area becomes smaller after the analyzer 6.

Furthermore, by generating a signal with an amplitude larger than C' and comparing this signal with the reproduction signal during recording, even if the amount of reflected light increases abnormally due to dust, etc., it can be detected as a recording abnormality. can.

[Effect of the Invention J According to the present invention, in a magneto-optical recording/reproducing device, recording and confirmation can be performed using one beam, and the recording can be confirmed almost simultaneously with the recording. have

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is an explanatory diagram of recording in the magneto-optical recording/reproducing apparatus. FIG. 3 is an explanatory diagram of reflected light obtained from each region. FIG. 4 is a waveform diagram showing each characteristic in the above embodiment. FIG. 5 is a block diagram showing a conventional magneto-optical recording/reproducing device. l...Semiconductor laser. 4... Perpendicular magnetization recording medium, 5... Polarizing beam splitter. 6...Analyzer. 11... Waveform shaping circuit, 12... Differential amplifier circuit. 13...Delay circuit, 15...Sampling circuit. Figure 2 A mouth: At the time of Ne η stage - Stone head 4b Hogan Z - Stone head 4 Poho Z, ・
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Claims (1)

[Claims] In a magneto-optical recording and reproducing device that records and reproduces predetermined information by irradiating a perpendicularly magnetized medium with a light beam, the reflected light when the medium is irradiated with a recording light beam is passed through an analyzer, and the amount of light passing through the analyzer is measured. What is claimed is: 1. A magneto-optical recording/reproducing apparatus characterized by having a recording abnormality recognition means for recognizing a recording abnormality based on the above.