JPH077536B2 - Magneto-optical disk device - Google Patents

Description

The present invention relates to a magneto-optical disk device, and more particularly to a control circuit suitable for preventing a temperature rise of a magnetic head.

[Conventional technology]

The magnetic head in the conventional magneto-optical disk device is, for example, as described in Japanese Patent Laid-Open No. 61-137201, (1) By dividing an electromagnetic coil which is a magnetic head into two, the magnetic field generation amount per coil is reduced. The amount of heat generated and the power consumption of the coil have been reduced. Further, by arranging these two-divided coils on both sides of the disk, a uniform magnetic field is obtained. (2) Further, one coil (on the side not on the optical head) is a large rectangular coil that is long in the disk radial direction, so that a magnetic field is generated over the entire disk radial direction, and this coil at the time of access is It has a configuration that does not require movement.

[Problems to be solved by the invention]

However, in the above-mentioned conventional technique, the temperature increase of the magnetic head is still caused although the temperature increase is divided by dividing the magnetic head into a plurality as in (1). Furthermore, the temperature rise of this magnetic head is
The air flow caused by the rotation of the magneto-optical disk undergoes a large change. However, in the above-mentioned conventional technology,
I have not touched on heat dissipation and temperature control by rotating the disk and technology for ensuring safety.

Also, as in (2), if a rectangular magnetic head that generates a magnetic field over the entire radial direction of the disk is used, the movement of this head at the time of access becomes unnecessary, but with this, the magnetic field is extended to unnecessary areas. There is a contradiction that not only is there a waste of generation, but the magnetic head becomes larger, and the effects of small size, power saving, low heat generation, etc. as originally described in (1) above cannot be obtained. .

The object of the present invention is to eliminate the above-mentioned problems of the prior art,
(EN) Provided is a magneto-optical disk device having a magnetic head capable of reliably preventing the magnetic head from further increasing in temperature, and being small in size, and requiring no movement during access, and having both safety and high efficiency.

[Means for solving problems]

To this end, the present invention provides a feedback back circuit that detects the number of rotations of the magneto-optical disk and controls the exciting current of the magnetic head, thereby preventing an abnormal temperature rise of the magnetic head. Further, according to the present invention, the magnetic head is divided into a plurality of heads arranged in the radial direction of the magneto-optical disk, and the magnetic head of a corresponding portion is selected and excited at the time of access, so that a magnetic field is generated only in a necessary portion. Perform a scoop operation. As a result, the magnetic head is not enlarged, and the mechanical access operation of the magnetic head and the mechanism are unnecessary.

[Action]

In the above structure, since the magnetic head generally generates a magnetic field within a few mm from the surface of the magneto-optical disk, it is radiatively cooled in forced convection by the air flow generated by the rotation of the disk. However, the disk rotation speed decreases, for example, when the rotation stops, the forced convection stops,
Magnetic heads must rely on heat dissipation by natural convection. In the heat dissipation by the natural convection, the amount of heat dissipation is as low as a fraction of the forced convection to a few tenths, so that the magnetic head causes an abnormal temperature rise. To prevent this temperature rise,
The present invention is provided with a rotation speed detector for detecting the rotation of the magneto-optical disk, and a rotation speed detection circuit for measuring the disk rotation speed from the output of this detector.
A comparison circuit for comparing with a specified rotation speed is provided, and a feedback back circuit for inputting the output of the comparator to the magnetic head drive circuit is added. As a result, when the disk rotational speed falls below the specified value, the information is transmitted to the magnetic head drive circuit by the feedback circuit, and the exciting current of the magnetic head is reduced or controlled to zero. Therefore, by setting the rotation speed of the magneto-optical disk, which is the limit of temperature rise of the magnetic head, as the specified rotation speed, it is possible to prevent abnormal temperature rise of the magnetic head.

Further, according to the present invention, the magnetic head is divided into a plurality of pieces and arranged in the disk radial direction, and this selection circuit is provided. When an access command is inputted from the address designating circuit, the magnetic head located corresponding to the corresponding track is provided. Was selected, and a magnetic field was generated by passing an exciting current to it. Therefore, since the magnetic head of the present invention makes an access by a magnetic sweep that generates a magnetic field at a required place, a mechanical access (spatial movement) operation and mechanism are unnecessary, and further divided into a plurality of parts. Since the small head is selected and used, the heat generation amount and the power consumption are small, and the operation time until a predetermined magnetic field is generated after energization can be short.

Therefore, if the two configurations of the present invention are used in combination,
It is possible to obtain a magnetic head and a magneto-optical disk device which are safe and excellent in efficiency.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a magneto-optical disk device showing a first embodiment of the present invention. In this figure, 1 is a magneto-optical disk having a magnetic film capable of recording and erasing signals by operating the orientation direction of magnetization, 2 is a motor for rotating the magneto-optical disk 1, 3 is a motor for driving and controlling the motor 3. The drive circuit, 4 is a rotation speed detector that detects the rotation speed of the motor 2 and outputs a signal according to the rotation, and 5 is a rotation speed detection circuit that measures the rotation speed of the motor 2 from the output of the rotation speed detector 4. Then, compare the detected number of revolutions with the number of revolutions specified in advance,
It has a feedback circuit which outputs the result. In addition, 6 irradiates the magneto-optical disk 1 with laser light,
An optical head having an optical system for recording, reproducing and erasing signals, 7 is a magnetic head which is an electric magnetic field generating means such as an electromagnetic coil, 8 is a magnetic head drive circuit for applying an exciting current to the magnetic head 7, and 9 is a magnetic head. The direction of the magnetic field generated by the head 7 is shown, and the direction is controlled by the direction of the exciting current in the same direction and in the opposite direction.

Next, the heat dissipation and temperature characteristics of the magnetic head 7 will be described.

Figure 2 shows the relationship between the wind velocity (m / sec) and the heat dissipation coefficient (kcal / m ² h ℃) when the magnetic head is placed in forced convection. Generally, the magnetic head 7 is provided in order to efficiently apply the generated magnetic field 9 to the magneto-optical disk 1.
Placed within a few mm of the surface of the. Therefore, in the vicinity of the arrangement position, an air flow associated with the rotation of the disc 1 exists. For example, when the wind speed is measured at a position 1 mm away from the surface at a radius of 30 mm of the disk 1, a wind speed of about 4.1 m / sec can be obtained at a rotation speed of 1800 rpm. This wind speed changes depending on the peripheral speed of the disk, that is, the number of revolutions. Therefore, the magnetic head 7 is cooled by the forced convection by generating an air flow by the rotation of the disk 1. Under the above wind speed of 4.1 m / sec, the heat dissipation coefficient is about 46 kcal / m ² h ℃. This heat dissipation coefficient changes as shown in the figure depending on the wind speed,
The faster the wind speed, the more the heat dissipation of the magnetic head 7 can be promoted. On the other hand, when the rotation speed of the disk 1 decreases, the heat dissipation coefficient decreases, and if the disk 1 stops, the magnetic head 7 will be cooled by natural convection. The heat dissipation coefficient in this natural convection is about 7.1 kcal / m ² h ° C, which is much lower than that in the case of strong convection when the disk 1 is rotating, so that the temperature of the magnetic head 7 rises rapidly.

FIG. 3 shows the relationship between the number of revolutions of the magneto-optical disk 1 and the temperature rise of the magnetic head 7. As shown in this figure, the temperature of the magnetic head 7 accelerates as the disk rotation speed decreases. This is because the wind speed decreases as described above.

From these figures, when the number of rotations of the disk 1 in the magneto-optical disk device decreases, before the magnetic head 7 exceeds the allowable temperature, the exciting current to be applied is decreased or reduced to zero to prevent the temperature rise. Can be said to be necessary.

Next, the rotation speed detector 4 will be described using a specific example.

FIG. 4 shows an example of the rotation speed detector 4.
The detector 4 of this embodiment is of a light detection type, and 10 is an LE.
A light emitting element such as D, 11 is a light receiving element such as a photodiode, and 12
Is a rotating disk attached to the rotating part of the motor 2 in FIG. 1, 13 is a mark provided on the disk 12 and having different reflectances, 14
Is an output signal after photoelectric conversion output from the light receiving element 11.

In these operations, first, the mark 13 on the disk 12 rotating with the motor 2 is irradiated with light from the light emitting element 10, and the reflected light is captured by the light receiving element 11. The received light intensity is a disc
The surface of 12 and the mark 13 have periodical changes because of their different reflectances. As a result, the light receiving element 11 outputs a signal 14 obtained by photoelectrically converting the change in the light amount.

In the present embodiment, the mark 13 is provided on the disc 12 attached to the rotating portion of the motor 2, but the present invention is not limited to this, and the mark 13 may be provided on the magneto-optical disc 1 to irradiate it with light. May use a method other than light detection, such as magnetic detection.

Next, the rotation speed detection circuit 5 will be described.

FIG. 5 shows a configuration example of the rotation speed detection circuit 5. (A) of this figure shows the rotation speed detector 4 (see FIGS. 1 and 4).
Figures refer) show examples of the case where rectangular-wave signal 14 is inputted, the period measuring circuit period t ₁ of the rectangular wave signals 14
The data is measured at 15 and is compared with the data 17, which is the reference period determined by the specified number of revolutions, by the comparator 16, and the result is output to the magnetic head drive circuit 8 (see FIG. 1). Therefore, this feedback circuit detects when the rotational speed of the magneto-optical disk 1 falls below the specified value and reduces the exciting current of the magnetic head 7 to zero or prevents it from rising in temperature.

Although the period of the signal 14 is measured in the above description, the pulse width t ₂ may be measured without being limited to this.

Further, FIG. 5B shows an example in which the sinusoidal signal 14 is input. In this configuration, the signal 14
When input to the voltage converter (f-to-H converter) 18, its output voltage 18a changes with frequency as shown in the figure. Therefore, the comparator 17 compares the data 17 which is the reference voltage determined from the specified rotation speed with the comparator 16 and outputs the result to the magnetic head drive circuit 8 to form a feedback back circuit similar to the above (a).

As described above, in the present invention, the feed back circuit for monitoring the number of revolutions of the magneto-optical disk 1 and detecting it when the value is lower than the specified value to reduce the exciting current of the magnetic head 7 or reduce it to zero. By providing the magnetic head 7, an abnormal temperature rise of the magnetic head 7 can be prevented.

Next, FIG. 6 shows a second embodiment of the present invention.
The magnetic head 7 and the magnetic head drive circuit 8 in FIG. 1 are improved.

In this figure, 7 is a magnetic head divided into a plurality (7a to 7c) in the radial direction of the magneto-optical disk 1, and 8 is a magnetic head arranged corresponding to the magnetic head 7 (8a to 8c). , 19 are divided magnetic heads 7a to 7c and drive circuits 8a to 8
A selection circuit for selecting a head and a circuit corresponding to the access destination track from c, 20 is an address for outputting the transfer destination track number to the selection circuit 19 and the access drive circuit of the optical head 6 (see FIG. 8). It is a designated circuit.

As shown in this figure, in the present embodiment, the address designating circuit 20 selects the magnetic head closest to the access destination track from 7a to 7c by the selecting circuit 19, and the corresponding magnetic head drive circuits 8a to 8c are selected. By instructing and controlling the energization of the excitation current, the access operation is performed by the magnetic sweep. With such a configuration, an access mechanism for moving the magnetic head 8 together with the optical head 6 is unnecessary, and the configuration of the magneto-optical disk device can be simplified. Also, the magnetic heads 7a to 7c to be excited are
Compared with the conventional one (Japanese Patent Laid-Open No. 61-137301), it is made smaller by dividing it into a plurality of parts, and the heat generation amount and power consumption of the magnetic heads 7a to 7c can be reduced, and the self-inductance is lowered. After energization, the response speed until the required magnetic field is generated becomes faster.

Next, FIG. 7 shows a third embodiment of the present invention.
This is a modification of the configuration of the magnetic head 7 in FIG.

As shown in this figure, in this embodiment, the magnetic head 7 is divided into a plurality of parts (7a to 7e) in the same manner as in the second embodiment described above,
The magneto-optical disks 1 are arranged in the radial direction, and in addition to this, a magnetic head 7 has a laminated structure, and the positions of the upper and lower heads are arranged so as to be shifted by half a pitch in the radial direction. By virtue of such construction, the present embodiment is the second embodiment of the present invention shown in FIG.
Not only the effect of the embodiment of FIG.
Magnetic fields 9a to 9e generated by .about.7e can be generated uniformly over the entire radial direction of the disk 1.

FIG. 8 shows a magneto-optical disk device incorporating the magnetic head 7 of FIG. In this figure, the parts denoted by the same reference numerals as those in FIGS. 1 and 4 to 7 are the same parts. As described above, the rotation speed detection circuit 5 monitors the rotation speed of the magneto-optical disk 1, and when the rotation speed falls below a specified value, feeds this to the magnetic head drive circuit 8 and
The exciting current of the magnetic head 7 applied from the drive circuit 8 is reduced or reduced to zero to prevent an abnormal temperature rise of the magnetic head 7. Further, the magnetic head 7 is divided into a plurality of parts, and the disk 1
7 has a structure shown in FIG. 7 in which the layers are arranged in the radial direction. These operations are performed by the address designating circuit 20 during access.
When the target track is output, the optical head 6 is moved to the target track by the access motor drive circuit 21. In the magnetic head 7, the head closest to the target track is selected by the selection circuit 19, and an exciting current flows from the corresponding magnetic head drive circuit 8 to generate a magnetic field. As described above, the magnetic head 7 of the present invention performs an access operation by a magnetic sweep that generates a magnetic field at a required position, and thus a mechanism system such as an access motor dedicated to the magnetic head 7 is not necessary. Further, by making the magnetic head 7 smaller, heat generation and power consumption can be reduced and the response speed can be increased.

〔The invention's effect〕

As described in detail above, according to the present invention, a feedback back circuit is provided for monitoring the number of rotations of the magneto-optical disk and reducing or zeroing the exciting current of the magnetic head when the number of rotations falls below a specified value. As a result, the temperature rise of the magnetic head can be prevented. Further, according to the present invention, the magnetic head is divided into small heads in the radial direction of the magneto-optical disk and arranged,
By selecting the magnetic head closest to the target track and performing the access operation by the magnetic sweep that generates magnetism, the magnetic field is efficiently generated only in the necessary part,
Heat generation and power consumption can be reduced, and the response speed can be increased. Therefore, by using the above two configurations in combination, a safe and efficient magnetic head and magneto-optical disk device can be constructed.

[Brief description of drawings]

1 is a block diagram of a magneto-optical disk device showing a first embodiment of the present invention, FIGS. 2 and 3 are heat radiation and temperature characteristic diagrams of a magnetic head, and FIGS. 4 and 5 are rotations in FIG. FIG. 6, FIG. 7, FIG. 7, and FIG. 8 of the number detection system are configuration diagrams showing another embodiment of the present invention. 1 ... Magneto-optical disk, 2 ... Motor 4 ... Rotation speed detector, 5 ... Rotation speed detection circuit 6 ... Optical head, 7 ... Magnetic head 8 ... Magnetic head drive circuit 9 ... Magnetic field, 19 ...... Selection circuit 20 ...... Address designation circuit

Claims (2)

[Claims] 1. A magneto-optical disk having a magnetic film capable of recording and erasing signals by scanning in the magnetization direction, and an optical system for irradiating the magneto-optical disk with laser light to record, reproduce and erase signals. In a magneto-optical disk device including at least an optical head and an electric magnetic field generating means including a magnetic head for generating a magnetic field, a detecting means for detecting a rotational speed or a peripheral speed of the magneto-optical disk, and a detecting means for the detecting means. Comparing means for comparing a value with a preset specified value, and operating in accordance with the comparison output of the comparing means, and when the rotational speed or the peripheral speed of the magneto-optical disk becomes lower than the specified value, the magnetic field A magneto-optical disk device, which is provided with a control means for reducing or zeroing the head exciting current. 2. The electric magnetic field generating means according to claim 1, wherein a plurality of head rows of a plurality of heads arranged in a radial direction of the magneto-optical disk device are stacked, and each head is provided. The rows are offset from each other in the radial direction of the magneto-optical disk, and the magnetic head facing the light spot position on the magneto-optical disk is energized to generate a magnetic field at the light spot position on the magnetic disk. Magneto-optical disk device characterized by.