JPH0346144A - Magneto-optical memory device - Google Patents

Abstract

PURPOSE:To prevent erroneous recording from being generated by detecting an impressed magnetic field for demodulation and recording in a magnetic head with use of electromagnetic induction and comparing the original driving signal of the impressed magnetic field for modulation with a detected signal. CONSTITUTION:An LD 4 is turned on with the quantity of light necessary for recording. A magnetic head driving circuit 6 makes a current (i) flow to a coil 1 in a direction corresponding to a modulation signal. At such a time, the magnetic field is generated in a core 3 and an induced voltage is generated in the both ends of a coil 2 by induced electromotive force. This induced voltage is detected by a detecting circuit 8. This detection signal is amplified by an amplifier 9 and a pulse wave is generated by a binary circuit 10. Next, signals Q1 and Q2, which are synchronized to a data clock, are obtained by detection timing matching circuits 11 and 12 and the modulation signal is compared with the detection pulse signal by a signal comparator circuit 13. Then, a head abnormality detecting signal is obtained. After the abnormality is detected, an MPU 14 stops the lighting of LD 4 or lowers the quantity of light not to erase recorded information.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magneto-optical memory device using a magneto-optic effect, and particularly relates to a technique for detecting an abnormality in a magnetic head that performs recording and erasing using a magnetic field modulation method. .

[Prior Art] A magnetic field modulation method is an overridable recording method for a magneto-optical memory device that is expected to be used as a large-capacity external storage device for information processing devices. Recording using this magnetic field modulation method is performed by irradiating a recording medium with a laser beam of constant intensity and reversing the direction of the applied magnetic field depending on the recorded information.

[Problem to be solved by the invention] If an abnormality occurs in the magnetic head that generates the applied magnetic field necessary for recording, recording (particularly overwriting) will cause problems with the information to be recorded and the information recorded on the recording medium. information will be lost. At least as long as normal rewriting is not performed, recorded data on the recording medium must be retained. Further, if an abnormality occurs in the magnetic head during a recording operation, this is detected as a slip-file error, but the cause of the erroneous recording cannot be determined, and if rewriting is performed, the above-mentioned contents will be repeated.

Therefore, it is necessary to detect an abnormality in the magnetic head, to prevent the loss of recorded data, and to clarify whether there is an abnormality in the magnetic head, which is one of the causes of erroneous recording.

An object of the present invention is to provide a magneto-optical memory device that can prevent the occurrence of erroneous recording by providing means for detecting an abnormality in the magnetic head as a self-diagnosis function of the magnetic head.

[Means for Solving the Problems] In order to achieve the above-mentioned object, a magneto-optical memory device according to claim 1 of the present invention is a magneto-optical memory device using a magnetic field modulation method. A means for detecting the applied magnetic field for recording using electromagnetic induction (hereinafter referred to as electromagnetic induction detection means), and comparing the original drive signal of the applied magnetic field for modulation recording with the detection signal from the electromagnetic induction detection means. means (hereinafter referred to as comparison means);

The magneto-optical memory device according to claim 2 is characterized in that the electromagnetic induction detection means is constituted by at least one generated magnetic field detection winding wound around a core constituting the magnetic head. .

Furthermore, the magneto-optical memory device according to a third aspect of the present invention is characterized by comprising means for controlling the amount of light of the recording/reproducing light source based on the signal output from the comparing means.

[Function] According to the magneto-optical memory device according to claim 1, the signal detected by electromagnetic induction can be said to be the magnetic field itself applied to the recording medium, so an abnormality in the applied magnetic field itself for modulation recording can be detected by another means. It will be detected. Note that it is preferable that the electromagnetic induction detection means be placed at a position where the magnetic field applied to the recording medium can be faithfully reproduced, and configured in such a manner.

Further, according to the magneto-optical memory device according to claim 2, there is no need to provide a new coil, and it can be constructed by simply winding the detection winding around the core in addition to the magnetic field generation winding, resulting in low cost and The applied magnetic field can be detected accurately.

Furthermore, according to the magneto-optical memory device according to claim 3, if the applied magnetic field is abnormal, the power can be immediately reduced to the reproduction level, so safety can be maintained during recording with the risk of information loss. can be increased.

According to one embodiment of the present invention, in addition to the coil for generating the applied magnetic field in the U-shaped or E-shaped core, one or more detection coils are wound to generate the applied magnetic field for modulation recording by electromagnetic induction (induced induction). Detection using electric power).

This detected voltage is similar to a modulated recording signal, and the magnitude of the voltage is proportional to the magnitude of the generated magnetic field. That is, if a voltage of a certain level or higher is generated, the magnetic head can detect that the externally generated magnetic field is sufficient for recording. Furthermore, when a pulse wave is generated depending on the polarity of the generated voltage, recorded information is reproduced. Therefore, this reproduction pulse and the modulation signal of the magnetic field head are compared, and if the data is the same, the magnetic head can judge that a sufficient modulation magnetic field is obtained for recording, and either one of the above must be satisfied. It can be determined that the condition is abnormal. Here, if the configuration according to claim 3 is adopted and the abnormality detection means is executed before overriding, it is possible to prevent the recorded data on the recording medium from disappearing. In addition, if an abnormality is detected during recording operation, by changing the laser intensity to below the playback level, the recorded data will not be lost after the detection, and if the abnormality occurs within the ECC's error correction capability, the recorded data will not be lost. It is also possible to play. It also becomes clear whether there is an abnormality in the magnetic head, which is one of the causes of verification errors.

[Example] Hereinafter, a magneto-optical memory device according to the present invention will be described in detail based on a specific example.

FIG. 1 is a circuit block diagram according to an embodiment of the present invention. 1 is a magnetic field generation winding that generates an externally applied magnetic field for recording data on a recording medium; 2 is a detection winding that detects changes in the externally applied magnetic field; 3 is a magnetic flux of the externally applied magnetic field; 4 is a semiconductor laser diode for recording and reproducing; 6 is a drive circuit for passing a current through the winding 1 and generating an externally applied magnetic field; 7 is a drive circuit for generating an externally applied magnetic field; an LD drive circuit for driving the semiconductor laser diode (LD) 4; 8 a detection circuit for extracting the detection signal obtained by the detection winding 2; 9 an amplifier for amplifying the detection signal of the detection circuit 8; 10 is a binarization circuit for pulsating the detection signal of the amplifier 9; 11 is a detection timing adjustment circuit for the output (detection pulse signal) of the binarization circuit 10; 12
13 is a detection timing circuit for adjusting the modulation signal for controlling the direction of the externally applied magnetic field; 13 is a comparison circuit for the detection pulse signal and the modulation signal; and 14 is a control system microprocessor.

FIG. 2 is a timing chart of abnormality detection during recording and LD irradiation stop in the magneto-optical memory of this embodiment. The operation of this embodiment will be described in detail with reference to FIGS. 1 and 2.

As shown in FIG. 2(a), when the recording operation is enabled, the LD 4 lights up with the amount of light necessary for recording. Further, the magnetic head drive circuit 6 is enabled, and a current i is caused to flow through the winding 1 in a direction corresponding to the modulation signal (FIG. 2(b)). At this time, a magnetic field is generated in the core 3, and an induced voltage is generated at both ends of the winding 2 due to the induced electromotive force. This induced voltage is detected by the detection circuit 8 (FIG. 2(C)). Also,
This signal is amplified by the amplifier 9, and the waveform shown in FIG. 2(d) is obtained. Since this signal is obtained as a differential waveform of the modulation signal (FIG. 2(b)), a pulse wave is generated by the binarization circuit 10 (FIG. 2(e)).

Now, the voltage level vth+ is such that a sufficient magnetic field is generated in the magnetic head and the direction of the magnetic field is reversed.

If the level of the binarization circuit is set to vth-, the modulation signal (Fig. 2 (b)) and the detection pulse signal (Fig. 2 (e)
)) matches. Therefore, in order to correct the delay time of the circuit, signals Ql and Q2 synchronized with the data clock (Fig. 2 (f)) are obtained by the detection timing adjustment circuit 11.12 (Fig. 2 (g), (h)). , and the signal comparison circuit 1
3, the modulation signal and the detection pulse signal obtained by the means are compared, and a head abnormality detection signal (Fig. 2 (i)) is obtained.
can be obtained. This head abnormality signal is input to the microprocessor 14, and after detecting the abnormality, it immediately sends a control signal to the LD drive circuit 7 to immediately stop lighting the LD 4 or to reduce the light intensity to a level that does not erase recorded information (second Figure (J)).

Therefore, it is possible to detect abnormalities in the magnetic head in real time and prevent the loss of recorded data.

[Effects of the Invention] As described above in detail, the magneto-optical memory device of the present invention can be used as a self-diagnosis function of a magnetic head, and can detect abnormalities in the following points.

■ Disconnection or short circuit of the core winding ■ Presence or absence of an externally generated magnetic field necessary for recording ■ The quality of the direction of the magnetic field generated by magnetic field modulation. This has the effect of increasing the reliability of the device.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram for explaining one embodiment of the magneto-optical memory of the present invention. FIG. 2 is a timing chart of abnormality detection during recording and LD irradiation stop in the magneto-optical memory of this embodiment.

Claims (3)

[Claims] (1) In a magneto-optical memory device using a magnetic field modulation method, a means for detecting a magnetic field applied to the magnetic head for modulation recording using electromagnetic induction (hereinafter referred to as electromagnetic induction detection means)
A magneto-optical memory device comprising: a means for comparing the original drive signal of the applied magnetic field for modulation recording with a detection signal from the electromagnetic induction detection means (hereinafter referred to as comparison means). (2) The magneto-optical memory device according to claim 1, wherein the electromagnetic induction detection means is constituted by at least one winding for detecting a generated magnetic field wound around a core constituting the magnetic head. (3) The magneto-optical memory device according to claim 1, further comprising means for controlling the amount of light from the recording/reproducing light source based on the signal output from the comparing means.