JPH02177002A - Magneto-optical recorder - Google Patents

Abstract

PURPOSE:To accurately control a permanent magnet and to add vertical bias magnetic field by providing two magnetic induction elements near the permanent magnet and controlling the rotation angle of the magnet in a timing when outputs from both elements coincide with each other. CONSTITUTION:Two magnetic induction elements 15a and 15b are arranged near the permanent magnet 14 along a plane orthogonally crossed with a rotary shaft 14a, a spaced angle theta apart. The outputs from the induction elements 15 are amplified 16 and supplied to 1st and 2nd comparison circuits 17 and 18. A range where the vertical component of the bias magnetic field on the film surface of a medium 11 has the fixed size or more is detected in the 1st comparison circuit 17. Then, the timing when the outputs from the 1st and the 2nd induction elements 15a and 15b coincide with each other within the above-mentioned size is detected in the 2nd comparison circuit 18. By stopping the permanent magnet 14 in this timing, the magnet is accurately controlled and the bias magnetic field in a vertical direction is added.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magneto-optical recording device that records information on, for example, a magneto-optical recording medium.

(Prior Art) Conventionally, magneto-optical recording devices capable of recording, reproducing, and erasing information have been equipped with a method for controlling the rotation angle of a permanent magnet in order to apply a bias magnetic field perpendicular to the magneto-optical recording medium. Some use magnetically sensitive elements. In such a magneto-optical recording device, a magnetically sensitive element is arranged near a permanent magnet, at a predetermined distance from the center of the rotation axis of the permanent magnet, and perpendicular to the magneto-optical recording medium. By comparing the output generated from this magnetically sensitive element according to the rotation angle of the permanent magnet with respect to the magneto-optical recording medium with a set value, it is possible to determine whether the magnetic field perpendicular to the magneto-optical recording medium due to the rotation of the permanent magnet is Detects a range in which the component has a size greater than a certain value. By controlling the rotation of the permanent magnet based on the detection timing thus obtained, a bias magnetic field in a direction perpendicular to the magneto-optical recording medium is applied.

However, in the method described above that controls the bias magnetic field, the position adjustment of the magnetic sensing element is delicate and takes time, and the rotation control of the permanent magnet may vary depending on the accuracy of the adjustment. there were.

In other words, the output waveform of the magnetically sensitive element varies depending on the positional relationship between the permanent magnet and the magnetically sensitive element, so the rotation angle of the permanent magnet changes greatly relative to the set value, resulting in variations in the position at which the permanent magnet stops. was there.

(Problems to be Solved by the Invention) As described above, in a device in which the rotation of a permanent magnet is controlled by the output of a single magnetically sensitive element, the position adjustment of the magnetically sensitive element is delicate and takes time. However, depending on the precision of the adjustment, there may be variations in the rotation control of the permanent magnet.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magneto-optical recording device in which the position of a magnetically sensitive element can be easily adjusted and the rotation of a permanent magnet can be accurately controlled.

[Structure of the Invention] (Means for Solving Labor Problems) In the magneto-optical recording device of the present invention, the magneto-optical recording device is disposed at a position facing a pickup with a magneto-optical recording medium interposed therebetween, and the magneto-optical recording device A permanent magnet that changes the polarity of the magnetic field applied to the medium, and a perpendicular plane to the rotation axis of this permanent magnet.
first and second magnetically sensitive elements arranged at a predetermined angle and the same distance from the center of the rotation axis; Second
a first detection means for detecting a range in which a perpendicular component of a magnetic field on the magneto-optical recording medium due to the rotation of the permanent magnet has a magnitude greater than a certain value from the output of the magnetically sensitive element;
．． a second detection means for detecting the timing at which the outputs of the second magnetically sensitive element match; and a detection timing of the second detection means obtained within the range specified by the first detection means. and a control means for controlling the rotation angle of the permanent magnet.

(Function) According to the above-described means, the rotation of the permanent magnet can be stopped at a position substantially perpendicular to the magneto-optical recording medium even if the position of the magnetically sensitive element is slightly shifted.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a magneto-optical recording device of the present invention.

That is, 11 is a disk-shaped magneto-optical recording medium, and this magneto-optical recording medium 11 is rotationally driven by a motor 12.

Below the magneto-optical recording medium 11, for example, a pickup 13 for irradiating light onto the magneto-optical recording medium 11 is provided so as to be movable in the direction of the arrow shown (in the radial direction of the magneto-optical recording medium 11). This pickup 13 uses a drive circuit (not shown) to emit light whose intensity is modulated according to the information to be recorded when recording information, and to emit light whose intensity is necessary for reproduction when reproducing information. ing.

Furthermore, when erasing information, light having the intensity necessary for erasing is irradiated.

The magneto-optical recording medium 1 facing this pickup 13
For example, a permanent magnet 14 extending in the radial direction of the magneto-optical recording medium 11 is provided above the magneto-optical recording medium 11 . This permanent magnet 14 is magnetized in its longitudinal direction, and is magnetized in a direction perpendicular to the longitudinal direction of the magnet 14 around a rotating shaft 14g so that a magnetic field generated from each magnetic pole can be applied to the magneto-optical recording medium 11. It is arranged so that it can rotate freely.

A magnetic sensing element section 15 is arranged near the permanent magnet 14 along a vertical plane perpendicular to the extending direction of the rotating shaft 14a. This magnetically sensitive element section 15 has two magnetically sensitive elements, and the output of each magnetically sensitive element is determined in the direction of the bias magnetic field with respect to the rotation angle of the permanent magnet 14 (
polarity) and its size.

The output of the magnetically sensitive element section 15 is supplied to an amplifier circuit 16,
After being amplified by this amplifier circuit 16, the first comparison circuit 1
7 and a second comparison circuit 18, respectively.

The first comparison circuit 17 calculates the perpendicular component of the bias magnetic field on the film surface of the magneto-optical recording medium 11 due to the rotation of the permanent magnet 4 from the output of the magnetically sensitive element section 15 supplied via the amplifier circuit 16. This is to detect a range that is larger than a certain size. In this case, the first comparator circuit 17 is provided with two equal set values above and below the zero level of the output of the magnetically sensitive element section 15. And these first
The second set value and the outputs of the two magnetically sensitive elements are compared, and the approximate magnitude of the bias magnetic field is detected from the output of the magnetically sensitive element that exceeds the respective set value.

The second comparison circuit 18 detects the timing at which the outputs of the magnetically sensitive element section 15 supplied via the amplifier circuit 16 match. In this case, the second comparison circuit 1
In step 8, the two outputs of the magnetically sensitive element are compared, and the second
The output of the magnetically sensitive element is greater than the output of the first magnetically sensitive element (output of the second magnetically sensitive element>output of the first magnetically sensitive element), or the output of the second magnetically sensitive element is greater than the output of the first magnetically sensitive element. is equal to or smaller than the output of the magnetically sensitive element (output of the second magnetically sensitive element ≦ output of the first magnetically sensitive element)
Each range is detected.

Above 1st. The output of the second comparator circuit 17 , 18 is supplied to a control circuit 19 . This control circuit 19 includes a drive circuit 20
The motor 21 that rotates the front permanent magnet 14 is controlled to be driven and stopped. In this case, the control circuit 19 outputs a drive signal for driving the motor 21 to the drive circuit 20 when rotating the permanent magnet 14. Further, when stopping the rotation of the permanent magnet 14, the first. Second comparison circuit 17
．． The timing for stopping the motor 21 is determined from the output from the motor 18, and a stop signal is output to the drive circuit 20 based on this timing.

That is, in the control circuit 19, the first comparison circuit 17
The edge portion of the signal waveform at the output of the second comparison circuit 18, which is obtained within the range specified by the output of the second comparison circuit 18, is determined. In this case, the bipedal magnetic sensing element section 15 should be arranged so that the edge portion of the required signal waveform coincides with the timing at which the permanent magnet 14 passes between the two magnetic sensing elements of the magnetic sensing element section 15. Accordingly, the timing for stopping the rotation of the motor 21 can be detected.

Therefore, based on the above detection timing, the motor 2
By controlling the rotation of permanent magnet 14 to stop, it is possible to control the rotation of permanent magnet 14 to stop at a position where a bias magnetic field perpendicular to magneto-optical recording medium 11 can be applied.

FIG. 2 shows the structure of the magnetically sensitive element section 15. As shown in FIG. That is, the magnetically sensitive element section 15 includes a first and a second
two magnetically sensitive elements 15a.

15b is provided. These first. The second magnetically sensitive elements 15a and 15b are each arranged at a position separated by a certain distance r from the center of the rotation axis 14a of the permanent magnet 14. Further, when the first magnetically sensitive element 15a is in a position where it applies a bias magnetic field perpendicular to the permanent magnet 14 or the magneto-optical recording medium 11, the first magnetically sensitive element 15a is located at a position where its output is maximum, that is, the It is arranged at a position perpendicular to the magnetic recording medium 11.

On the other hand, when the permanent magnet 14 is rotated in the direction of the arrow in the figure (clockwise), the second magnetically sensitive element 7-15b is rotated at a predetermined angle counterclockwise with respect to the first magnetically sensitive element 15a. It is placed at a position with θ. For example, when the motor 21 is configured by a pulse motor, the predetermined angle θ is set to match the movement width of the permanent magnet 14 that can be moved by one drive pulse supplied from the drive circuit 20. There is. Therefore, the first. By stopping the supply of drive pulses from the drive circuit 20 to the motor 21 based on the timing when the permanent magnet 14 passes through the center between the second magnetically sensitive elements 15a and 15b, the magneto-optical recording medium 11 is The rotation of the permanent magnet [4] can be stopped at a position where a bias magnetic field in the vertical direction can be applied.

FIG. 3 shows the perpendicular component Hz of the magnetic field on the film surface of the magneto-optical recording medium 11 with respect to the rotation angle of the permanent magnet 14, the output waveforms H, , H2 from the amplifier circuit 16 with respect to this perpendicular component Hz, and the first The output waveform S1 from the comparison circuit 17 of
, and the output waveform S2 from the second comparator circuit 18.

The rotation control of the permanent magnet will be explained below with reference to FIG.

For example, assume that the drive circuit 20 is controlled by a drive signal from the control circuit 19 and the drive pulse from the drive circuit 20 is supplied to the motor 21.

Then, as the motor 21 rotates in a predetermined direction, the permanent magnet 14 is rotated clockwise.

In this state, a signal corresponding to the direction (polarity) and the magnitude of the bias magnetic field with respect to the rotation angle of the permanent magnet 14 is outputted from the magnetically sensitive element section 15 from each of the magnetically sensitive elements 5a and 15b. The first . They are respectively supplied to second comparison circuits 17 and 18.

In the first comparator circuit 17, the first . Second magnetically sensitive element 15a.

The outputs H, , H2 of 15b are the first. Second set value V1. V
2, and a detection signal S1 corresponding to a range exceeding the respective set values Vl and V2 is detected and supplied to the control circuit 19.

On the other hand, in the second comparison circuit 18, the output H1 of the first magnetically sensitive element 15a supplied via the amplifier circuit 16 and the second
The output H2 of the second magnetically sensitive element 15b is compared with the output H2 of the second magnetically sensitive element 15b.
5a is greater than the output H1 of the first magnetically sensitive element 15a () I2 > Hl), or the output H2 of the second magnetically sensitive element 15b is equal to or smaller than the output H1 of the first magnetically sensitive element 15a (
A detection signal S2 corresponding to the range H2≦H1) is detected and supplied to the control circuit 19.

Outputs S1. from the first and second comparison circuits 17.18. S2
is supplied, in the control circuit 19, for example, the first
The AND of the output S1 of the comparison circuit 17 and the output S2 of the second comparison circuit 18 is calculated. That is, the noise n etc. at the output S2 of the second comparison circuit 18 are removed, and the signal at the output S2 of the second comparison circuit 18 is within the range specified by the output S1 of the first comparison circuit 17. The timing at which the permanent magnet 14 passes between the two magnetically sensitive elements 15a and 15b is detected from the edge portion a of the waveform.

In this way, the permanent magnet 14 has two magnetically sensitive elements 15a,
15b when the timing of passing between them is detected,
A stop signal is supplied from the control circuit 19 to the drive circuit 20 based on the detection timing. Then, drive circuit 2
The supply of drive pulses from 0 to the motor 21 is stopped, and the rotation of the motor 21 is thereby braked, allowing the permanent magnet 14 to apply a perpendicular bias magnetic field to the magneto-optical recording medium 11. stopped in position.

As described above, the timing at which the permanent magnet passes between two magnetically sensitive elements is detected, and based on this detection timing, the driving of the motor that rotates the permanent magnet is stopped.

That is, two magnetically sensitive elements are arranged as a pair, and the output of each magnetically sensitive element according to the rotation angle of the permanent magnet is used to detect the timing to stop the rotation of the permanent magnet. As a result, even if the position of the magnetic sensing element relative to the permanent magnet shifts slightly and the amplitude of the output waveform of the magnetic sensing element changes depending on the distance from the permanent magnet, there is no major change in the timing of stop control, so the permanent magnet is stopped. It is possible to reduce the variation in the position of the robot and stop it at an approximately constant position. Therefore, the accuracy of position adjustment of the magnetically sensitive element can be relaxed, and the rotation of the permanent magnet can be accurately controlled regardless of a slight positional deviation of the magnetically sensitive element.

In the above embodiment, the permanent magnet is rotated by a pulse motor, but the permanent magnet is not limited to this, and for example, a DC
It can also be applied to devices that are rotated by a (DC) motor. In this case, the DC motor may be gradually decelerated based on the detection timing.

It goes without saying that various other modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As detailed above, according to the present invention, there is provided a magneto-optical recording device in which the position of the magnetically sensitive element can be easily adjusted and the rotation of the permanent magnet can be accurately controlled. can be provided.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic diagram showing the configuration of a magneto-optical recording device, FIG. 2 is a diagram showing the configuration of a magnetically sensitive element section, and FIG. FIG. 3 is an output waveform diagram shown to explain rotation control. 11... magneto-optical recording medium, 13... pickup,
14... Permanent magnet, 15... Magnetic sensing element section, 15
a. 15b...Magnetic sensing element, 17...First comparison circuit (first detection means), 18...Second comparison circuit (second
(detection means), 19... control circuit (control means),...
·motor.

Claims (1)

[Scope of Claims] A permanent magnet that is disposed at a position facing a pickup with a magneto-optical recording medium in between, and whose rotation changes the polarity of a magnetic field applied to the magneto-optical recording medium, and a rotation axis of the permanent magnet. A first and a second are disposed on a vertical plane at a predetermined angle and at the same distance from the center of the rotation axis.
a magnetic sensing element; and a first magnetic sensing element for detecting, from the outputs of the first and second magnetic sensing elements, a range in which a perpendicular component of the magnetic field on the magneto-optical recording medium due to the rotation of the permanent magnet has a magnitude of a certain level or more. 1 detection means, a second detection means for detecting the timing at which the outputs of the first and second magnetically sensitive elements coincide, and the second detection means obtained within the range specified by the first detection means. 1. A magneto-optical recording apparatus comprising: a control means for controlling the rotation angle of the permanent magnet based on the detection timing of the detection means.