JPH0512819A - Signal recording device - Google Patents

Abstract

PURPOSE:To accurately keep a constant space between a magneto-optical disk and a magnetic head. CONSTITUTION:The magnetic head 15 is set on a base plate 18 and a capacitance detecting electrode 20 is provided on the base plate 18 as well. The height of the base plate 18 to the disk 1 is controlled so that the capacitance between the electrode 20 and the disk 1 or ground. A driving coil 27 is integrated with the base plate 18. The base plate 18 is supported by an arm 19 freely and movably in vertical direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal recording device for magnetically or magneto-optically recording a signal.

[0002]

2. Description of the Related Art An apparatus for recording / reproducing signals using a magneto-optical disk has a means for projecting a light beam (laser beam) on the disk and a magnetic head for applying a magnetic field. There are two types of recording methods, an optical modulation method and a magnetic field modulation method. In any case, a magnetic head is required in addition to the light beam projection means.

By the way, in order to give a strong magnetic field to the magneto-optical disk, it is desirable to bring the magnetic head as close to the magneto-optical disk as possible. However, if they are brought too close to each other, the magnetic head may come into contact with the disk due to surface wobbling of the disk, etc., and either one or both may be damaged.
To solve this type of problem, Japanese Patent Laid-Open No. 2-252152 discloses controlling the vertical position of the magnetic head based on a focus servo signal in the optical head.

[0004]

However, the focus servo signal does not always accurately indicate the distance between the magnetic head and the disk.

Therefore, an object of the present invention is to accurately detect the distance between the magnetic head and the disk with a simple structure, and to control so as to keep the above distance constant. To provide a device.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an apparatus for magnetically or magneto-optically recording a signal on a recording medium disc, wherein a space is provided between the main surface of the disc and the disc during recording. A magnetic head arranged to face each other; a head supporting mechanism supporting the magnetic head so that the magnetic head can move in a direction perpendicular to the main surface of the disk or in a direction having a component of this direction; An interval detection electrode arranged to face the disk for detecting the interval between the magnetic head and the disk based on capacitance, and the interval for maintaining a constant interval between the magnetic head and the disk. Magnetic head position control means for controlling the position of the magnetic head in the vertical direction so that the capacitance between the detection electrode and the disk or ground becomes a predetermined value. It is intended according to the signal recording apparatus according to claim is.

It is desirable that the gap detecting electrode is movably supported together with the magnetic head by the head supporting mechanism. Further, it is desirable that the magnetic head and the distance detection electrode are provided on a common substrate. Further, it is desirable that the distance detecting electrode is a metal film printed on the substrate. Further, it is desirable that the winding of the magnetic head be formed on the substrate by printing. In addition, a gap detection electrode is formed on one main surface of the substrate facing the disc,
It is desirable that a through hole is formed in the substrate for electrically leading out the distance detection electrode to the other main surface of the substrate.
Further, the winding of the magnetic head can be formed of a laminated substrate, and the gap detection electrodes can be provided on the laminated substrate. Further, it is desirable to arrange the magnetic head and the gap detection electrodes in the circumferential direction or the tangential direction of the concentric or spiral track on the disk. Further, it is desirable to form the interval detection electrode in the longitudinal direction in the circumferential direction or the tangential direction. Also, a plurality of gap detecting electrodes can be arranged. Further, a plurality of gap detecting electrodes can be arranged at different positions in the radial direction of the disc.

[0008]

According to the invention of claim 1, the distance between the magnetic head and the disk is detected based on the capacitance between the distance detecting electrode and the disk or the ground, and the distance is feedback-controlled based on this. It is possible to keep the distance between the disk and the magnetic head constant. By supporting the gap detecting electrode and the magnetic head by a common supporting mechanism as described in claim 2, the gap detecting mechanism can be simplified and the gap can be accurately detected. When the magnetic head and the gap detection electrode are provided on the common substrate as described in claim 3, the configuration is simplified and the detection accuracy is improved. If the gap detecting electrodes are formed on the substrate by printing as described in claim 4, the configuration becomes simple. By forming the winding by printing as described in claim 5, miniaturization is achieved. Wiring is facilitated by providing the through holes as described in claim 6. If the winding is formed of a laminated substrate as described in claim 7, it is possible to use this as a substrate for the distance detection electrode, and miniaturization is achieved. By arranging the magnetic head and the distance detection electrode in the circumferential direction or the tangential direction as described in claim 8, it becomes possible to detect the distance less affected by the pattern of the magnetic layer or the metal layer on the disk. That is, it is possible to obtain the electrostatic capacitance in the circumferential area or the outer peripheral area of the disk in the same manner as in the central area. By forming the gap detecting electrode in the longitudinal direction as shown in claim 9, the same effect as that of claim 8 can be obtained. By providing a plurality of gap detecting electrodes as described in claim 10, the gap can be controlled so as to keep the magnetic head parallel to the disk. By disposing a plurality of gap detecting electrodes in the radial direction of the disc as described in claim 11, the gap detecting accuracy can be enhanced by selectively using the gap detecting electrodes on the inner and outer circumference sides of the disc.

[0009]

[First Embodiment] A magneto-optical recording / reproducing apparatus according to the first embodiment of the present invention will now be described with reference to FIGS.
As shown in FIG. 1, the magneto-optical recording / reproducing apparatus includes a turntable 2 supporting a magneto-optical disk 1, a motor 3 coupled thereto, a signal converter 4, and a signal converter 4 for the disk 1. And a moving device 5 for moving in the radial direction.

The magneto-optical disk comprises a synthetic resin substrate 6 and a well-known magnetic material layer 7 having a property that a region formed on the synthetic resin substrate and heated to the Curie temperature is inverted in the direction of the external magnetic field. , Synthetic resin coating layer 8.

The signal converter 4 is an optical head 9 shown in principle.
Have. The optical head 9 comprises a laser light source 10 and an objective lens 11, and projects a light beam (laser beam) 12 onto the disk 1. A focus control system, which is well known in the field of a magneto-optical disk recording / reproducing apparatus or an optical disk player, is provided in order to focus and project the light beam 12 on the disk 1, but these are not shown. The optical head 9 is attached to a head carriage 14 which is guided in the radial direction of the disk 1 by a guide 13.

The signal converter 4 has a magnetic head 15 in addition to the optical head 9. The magnetic head 15 comprises a magnetic core 16 and a winding 17, as shown in principle in FIG. The core 16 is supported by the insulating substrate 18 and faces the disc 1. The winding 17 is the main surface 18a of the substrate 18 facing the disk.
It is formed by printing on. Substrate 18 has its main surface 1
8a is arranged so as to face the disk 1, and is fixed to the tip of a support arm 19 made of a pair of metal plates having a spring property. The arm 19 is cantilevered by the carriage 14 and extends in the radial direction of the disk 1.

On the main surface 18a of the substrate 18 facing the disk, a gap detecting electrode 20 and a guard electrode 21 made of a metal film formed by printing are provided. The gap detection electrode 20 constitutes a capacitance sensor that detects a change in gap due to a change in capacitance with the disc 1. The substrate 18 is provided with through holes 22, 23, 24, 25 extending from the disk facing side main surface 18a to the opposite side main surface 18b, and is used for electrical connection of the winding wire 17, the gap detecting electrode 20, and the guard electrode 21. It's being used. Magnetic head 15
And the gap detecting electrode 20 are arranged in the direction of the tangent line 26 of the spiral or concentric track of the disk 1. The arrangement direction can be the circumferential direction of the track.

A moving coil, that is, a drive coil 27, which constitutes a device for moving the magnetic head 15 in the direction perpendicular to the main surface of the disk 1, is fixed to the substrate 18. Since the drive coil 27 is placed in the magnetic flux generated by the magnet 28 fixed to the carriage 14, it changes when a current is applied to the drive coil 27. That is, the drive coil 27 moves on the same principle as the voice coil of the speaker.

FIG. 3 shows the electrostatic capacitance C1 between the gap detecting electrode 15 and the disc 1 and the electrostatic capacitance C2 between the disc 1 and the ground member 29 such as a turntable. When the distance between the magnetic head 15 and the disk 1 changes, the distance D between the distance detecting electrode 20 and the disk 1 also changes, and the electrostatic capacitance C1 changes. Since the disk 1 is fixed to the turntable 2, the electrostatic capacitance C2 does not substantially change in response to the change in the distance D. Therefore, the distance D can be known by detecting the electrostatic capacitance between the distance detection electrode 20 and the ground.

FIG. 4 shows a feedback control circuit 29 of the drive coil 27 based on the capacitances C1 and C2 between the gap detecting electrode 20 and the ground. The control circuit 29 includes an AC power supply 30 for applying an AC voltage to the resistor R1 through the capacitors C1 and C2.
Have. The AC voltage of the AC power supply 30 is resistance R1 and capacity C
It is divided by 1 and the impedance of C2 and input to the amplifier 31. The bandpass filter 32 connected to the output of the amplifier 31 extracts the frequency component of the AC voltage. The detection signal obtained from the bandpass filter 32 is the diode 3
It is converted into direct current by the rectifying and smoothing circuit composed of 3 and the capacitor 34. The detection signal converted into direct current is divided by the variable resistor 35 and then input to the compensation circuit 36. Compensation circuit 36
Is a circuit for compensating for the non-linearity between the interval D and the detection voltage, and for making the relationship between the interval D and the detection voltage linear. The output of the compensation circuit 36 is given to one input terminal of the error amplifier 37. The error amplifier 37 generates an output (error output) corresponding to the difference between the reference voltage of the reference voltage source 38 connected to the other input terminal and the detected voltage, and outputs this output to the drive coil 27.
Apply to. A drive amplifier circuit can be provided between the error amplifier 37 and the drive coil 27.

There are roughly two methods for moving the magnetic head 15 and the gap detecting electrode 20 by the drive coil 27. First, the position of the arm 19 is determined so that the magnetic head 15 is at a desired position with respect to the disk 1 when the current of the drive coil 27 is zero, and when the distance D becomes smaller than a predetermined value, the error amplifier A negative output voltage is generated from 37, a current in a direction to widen the interval D is passed through the drive coil 27, and when the interval D becomes larger than a predetermined value, a positive output voltage is generated from the error amplifier 37 to narrow the interval. This is a method of passing a current in a direction to the drive coil. Second
Is a method of changing the current of the drive coil 27 so that the interval D is set to a predetermined value when a predetermined current is applied to the drive coil 27 and the interval D is corrected according to the change of the interval D. Is.

When writing a signal with this magneto-optical recording / reproducing apparatus, for example, a magnetic field modulation method is adopted, and a non-modulated light beam 12 is projected onto the recording portion of the magnetic layer 7 of the disk 1 to heat it, and the magnetic field is recorded there. A magnetic field is applied by the head 15. The portion heated by the light beam 12 is magnetized in the direction corresponding to the direction of the external magnetic field applied from the magnetic head 15. When the magnetic field modulation method is adopted, the winding 17 of the magnetic head 15 is configured so that currents in both the forward and reverse directions are selectively passed.

The magneto-optical recording / reproducing apparatus described above has means for independently detecting the distance D between the magnetic head 15 and the disk 1, and controls the distance D independently, so that the distance D is controlled. Can be done accurately. Further, since the distance D is detected based on the distance detection electrode 20 provided on the same substrate 18 as the magnetic head 15, the distance D can be accurately detected with a simple configuration. Also, winding 17
Further, since the distance detection electrode 20 is formed on the substrate 18 by printing, these can be easily formed. Further, since the magnetic head 15 and the distance detecting electrode 20 are arranged in the track tangential direction, the distance detecting electrode 20 is located at the same position as the magnetic head 15 in the radial direction of the disk 1, and is located on the inner peripheral side of the disk 1. And the magnetic layer 7 on the outer peripheral side
To face. Further, since the winding wire 17 and the gap detection electrode 20 are electrically connected to the upper surface of the substrate 18 through the through holes 22, 23, 24, connection to an external circuit can be easily achieved. In addition, since the magnetic head 15 and the gap detecting electrode 20 are provided on the substrate 18, the substrate 18 easily floats when the disk 1 rotates.

[0020]

[Second Embodiment] Next, a second embodiment will be described with reference to FIG. However, the magnetic head 15 and the gap detection electrode 20
The other parts are the same as those in FIGS. 1 to 4, and are not shown in FIG. In this embodiment and the embodiments described later, the description of the parts common to the first embodiment will be omitted. In the second embodiment, the coil 17 of the magnetic head 15 is embedded in the laminated substrate 40. The laminated substrate 40 is a unit substrate 40a, 40b, 40c provided with one turn of the winding wire 17,
40d is laminated, and the covering substrate 40e is arranged on the 40d and integrated. The windings 17 on each board are connected to each other in a spiral shape. Interval detection electrode 2
0 is provided on the lower surface of the laminated substrate 40. With this configuration, the winding 17 of the magnetic head 15 can be downsized and mass-produced.

[0021]

[Third Embodiment] In the embodiment shown in FIG. 6, a magnetic head 15 is used.
The pattern of the distance detection electrode 20 on the substrate 18 including the is formed longitudinally in the track tangential direction indicated by the straight line 26. As a result, the gap detecting electrode 20 can be opposed to the magnetic layer 7 or the metal layer of the disc 1 on the inner and outer peripheral sides of the disc 1.

[0022]

Fourth Embodiment In the embodiment shown in FIG. 7, two gap detecting electrodes 20a and 20b are formed along a straight line 26, that is, a track tangential direction on a substrate 18 including the magnetic head 15. The two gap detecting electrodes 20a and 20b are connected in parallel and are connected to the control circuit 29 of FIG. By forming the plurality of distance detecting electrodes 20a and 20b in this manner, it is possible to detect the distance with little deviation.

[0023]

Fifth Embodiment In the embodiment shown in FIG. 8, the two gap detecting electrodes 20a and 20b are connected to independent control circuits 29a and 29b, and the two drive coils 27a and 27b are connected to the control circuit 29.
It is controlled by a and 29b respectively. The arrangement of the distance detection electrodes 20a and 20b in FIG. 8 is the same as that in FIG. The two drive coils 27a and 27b are respectively fixed to one end and the other end of the substrate 18 in the track connecting direction, and the cores 16a and 16b are inserted therein. In this way, the plurality of distance detection electrodes 20a and 20b and the plurality of drive coils 27a,
By providing 27b, the parallelism of the substrate 18 with respect to the disk 1 can be increased.

[0024]

[Sixth Embodiment] In the embodiment shown in FIG. 9, four gap detecting electrodes 20a, 20b, 20c and 20d, four drive coils 27a, 27b, 27c and 27d and four control circuits 29a and 29b are provided. 29c and 29d are provided.
With this structure, the parallelism of the substrate 18 with respect to the disk 1 becomes higher than that in FIG.

[0025]

MODIFICATION The present invention is not limited to the above-mentioned embodiments, and the following modifications are possible. (1) As shown in FIG. 10, three gap detecting electrodes 27 are provided.
a, 27b, 27c and three drive coils 27a, 27
b, 27c and three control circuits 29a, 29b, 29c
Can be provided. (2) As shown in FIG. 11, the first and second gap detecting electrodes 20a and 20b are divided into the left side and the right side of the center of the substrate 18 extending in the track connecting direction indicated by the straight line 26.
May be provided, and this may be selectively connected to the control circuit 29 via the contacts a and b of the switch SW. When the center of the disk 1 is on the left side of the substrate 18 in FIG. 11, the first distance detecting electrode 20a is used for detecting the distance D on the outer peripheral side of the intermediate track of the disk 1, and the second distance detecting electrode is used. The electrode 20b is used for detecting the gap on the inner peripheral side of the intermediate track. In addition, in FIG. 11, the first gap detecting electrode 20a can be provided at the position of the broken line. (3) Although the core 16 of the magnetic head 15 is shown in principle, it may be a C-shaped core. (4) The substrate 18 is not supported by the arm 19 in a cantilever manner, and a component corresponding to the arm 19 is arranged on the left side of the substrate 18,
It can be supported from both sides to increase parallelism. Also,
The substrate 18 can be supported by a gimbal spring. (5) The magnetic head 15 may be kept in contact with the disk 1 when the disk 1 is not rotating, and the magnetic head 15 may be levitated from the disk 1 when the disk 1 reaches a predetermined number of rotations or more. (6) The present invention can be applied to a magnetic disk device in which signals are magnetically recorded on a magnetic disk only by the magnetic head 15 without using a light beam. (7) The magnet 28 is fixed to the substrate 18, and the drive coil 27
Can be fixed to the carriage 14. (8) The circuit for detecting the electrostatic capacitance between the gap detection electrode 20 and the ground is not limited to that shown in FIG. 4, and a capacitance change is detected by a circuit connecting the detection electrostatic capacitance and three impedance elements in a bridge manner. can do. (9) The disk 1 can be provided with a transparent metal layer for capacitance detection.

[0026]

According to the inventions of the respective claims, it becomes possible to accurately set the distance between the disk and the magnetic head within a predetermined range.

[Brief description of drawings]

FIG. 1 is a front view showing a magneto-optical recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view for explaining the capacitance of a gap detection electrode.

FIG. 4 is a circuit diagram showing a control circuit that controls a drive coil by the capacitance of a gap detection electrode.

FIG. 5 is a cross-sectional view showing a magnetic head of a second embodiment and its vicinity.

FIG. 6 is a view similar to FIG. 2 showing the arrangement of gap detection electrodes on the substrate of the third embodiment.

FIG. 7 is a diagram similar to FIG. 2 showing the arrangement of gap detection electrodes of a fourth embodiment.

FIG. 8 is a diagram showing a layout and control method of a gap detection electrode and a drive coil according to a fifth embodiment.

FIG. 9 is a diagram showing an arrangement and control method of a gap detection electrode and a drive coil of a sixth embodiment.

FIG. 10 is a diagram showing an arrangement and control method of a gap detection electrode and a drive coil of a modified example.

FIG. 11 is a diagram showing the arrangement and control method of the distance detection electrodes of another modification.

[Explanation of symbols]

1 Magneto-optical disk 9 Optical head 15 Magnetic head 18 substrates 19 arms 20 Interval detection electrode 27 Drive coil

Claims (11)

[Claims] 1. A device for magnetically or magneto-optically recording a signal on a recording medium disk, wherein a magnetic head is arranged to face the main surface of the disk at a time of recording, and the magnetic head is a disk of the disk. A head support mechanism that supports the magnetic head so as to be movable in a direction perpendicular to the main surface or in a direction having a component of this direction; and a distance between the magnetic head and the disk based on capacitance. An interval detection electrode that is arranged to face the disk for detection, and an electrostatic capacitance between the interval detection electrode and the disk or ground in order to keep the interval between the magnetic head and the disk constant. And a magnetic head position control means for controlling the position of the magnetic head in the vertical direction so that is a predetermined value. 2. The signal recording device according to claim 1, wherein the gap detecting electrode is movably supported together with the magnetic head by the head supporting mechanism. 3. The signal recording device according to claim 2, wherein the magnetic head and the gap detecting electrode are provided on a common substrate. 4. The signal recording device according to claim 3, wherein the gap detecting electrode is a metal film formed on the substrate by printing. 5. The signal recording device according to claim 3, wherein the magnetic head comprises a core and a winding, and the winding is formed on the substrate by printing. 6. The distance detecting electrode is formed on one main surface of the substrate facing the disk, and the distance detecting electrode is electrically provided on the other main surface of the substrate. The signal recording device according to claim 3, wherein a through hole for leading out is formed. 7. The magnetic head comprises a winding and a core, the winding is embedded in a laminated substrate, and the gap detecting electrode is provided in the laminated substrate. 2. The signal recording device according to 2. 8. The signal recording device according to claim 2, wherein the magnetic head and the gap detection electrode are arranged in a circumferential direction or a tangential direction of concentric or spiral tracks on the disk. 9. The signal recording device according to claim 8, wherein the distance detecting electrode is formed longitudinally in the circumferential direction or the tangential direction. 10. The signal recording device according to claim 2, wherein a plurality of the distance detecting electrodes are arranged. 11. A signal recording device, wherein a plurality of the distance detecting electrodes are arranged at different positions in the radial direction of the disk.