JPH06150206A - Positioning apparatus of magnetic head - Google Patents

Abstract

PURPOSE:To make a magnetic head of a magnetic field modulating type apparatus compact in structure and to reduce the consuming power by positioning the magnetic head precisely. CONSTITUTION:The positioning apparatus is provided with a magnetic head 2 having a magnetic field modulating coil 2b at a core 2a, a four-dividing optical sensor 1 set at an end face 2c of the magnetic head 2 for impressing a magnetic field to the magnetic head, an actuator 4 supporting the magnetic head 2 in a manner to shift in two directions so that the optical sensor 1 confronts to an objective lens 9 of an optical pickup 7 via a magneto-optic disc D, and a control means for controlling and driving the actuator 4 based on output signals from the optical sensor 1 to make an optical axis of laser beams 8 projected from the optical pickup 7 agree with the maximum position of a vertical magnetic field from the end face 2c of the magnetic head 2, thereby shifting the magnetic head 2 in two dimensions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for accurately positioning a magnetic head used in a magnetic field modulation type magneto-optical disk device at a position opposed to an objective lens of an optical pickup with a magneto-optical disk interposed therebetween. Regarding

[0002]

2. Description of the Related Art A magnetic field modulation type magneto-optical disk device is
This is an apparatus for recording information on a magneto-optical disk by heating the recording position of the magneto-optical disk with a laser beam and modulating the direction of an externally applied magnetic field with respect to the recording position.

In Japanese Patent Laid-Open No. 4-23248, based on the output of a four-division optical sensor provided on the optical pickup side, the magnetic head is placed at a position facing the objective lens of the optical pickup.
A device for accurate positioning is disclosed.
In the above device, the output laser from the optical pickup is
The beam reaches the four-division optical sensor on the side of the optical pickup through the objective lens, the magneto-optical disc, the light reflection area on the end face for applying the magnetic field of the magnetic head, the magneto-optical disc, the objective lens, and the polarization beam splitter. The drive control circuit uses two magnetic heads so that the difference between the output signals of the four-division optical sensor is zero.
Control movement by dimension. As a result, the magnetic head is positioned at a position facing the objective lens.

[0004]

In the magnetic field modulation type magneto-optical disk apparatus, the magnetic head is mechanically supported by an arm provided so as to extend from the optical pickup side while bypassing the magneto-optical disk. There is. That is, the magnetic head is mechanically connected to the optical pickup side, and is configured to access the recording position (same part) of the magneto-optical disk from the front and back of the disk in an interlocking manner. As a result, a mechanical mounting accuracy problem occurs, and the magnetic head is
It becomes difficult to position accurately at a position facing the objective lens on the optical pickup side. In order to deal with this, the magnetic head is made large in size so as to absorb an error in mounting accuracy. However, in this method, the scale of the modulation circuit becomes large and power consumption also becomes large.

On the other hand, in the device of the above-mentioned Japanese Patent Laid-Open No. 4-23248, the laser beam incident on the four-division optical sensor is transmitted through the magneto-optical disk twice, and is further reflected by the polarization beam splitter. Has been reached, the four-segment photosensor is reached. For this reason, the intensity of the laser beam upon entering the four-division optical sensor becomes extremely small, which makes detection difficult. That is, it becomes exactly the same as the noise level, and accurate control becomes difficult.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a device capable of accurately positioning a magnetic head at a position facing an objective lens on the optical pickup side without increasing the size of the magnetic head and its modulation circuit.

[0007]

According to the present invention, there is provided a magnetic head comprising a core and a magnetic field modulation coil, a four-division optical sensor provided on an end face for applying a magnetic field of the magnetic head, and a four-division optical sensor. Is an actuator for supporting the magnetic head in a two-dimensionally displaceable manner so as to face the objective lens of the optical pickup with the magneto-optical disk interposed therebetween, and the optical axis of the laser beam emitted from the optical pickup is the magnetic head. A magnetic head positioning device having a control means for two-dimensionally displacing the magnetic head by drivingly controlling the actuator based on the output signal of the four-division optical sensor so as to match the maximum position of the vertical magnetic field from the end face. Is.

[0008]

The laser beam output from the optical pickup reaches the four-division optical sensor on the end face for applying the magnetic field of the magnetic head through the objective lens and the magneto-optical disk. The control means drives and controls the actuator based on the detection signal from the four-division optical sensor to move the magnetic head two-dimensionally. Thus, the optical axis of the laser beam is aligned with the maximum position of the vertical magnetic field generated from the end face of the magnetic head.

[0009]

EXAMPLES Examples of the present invention will be described below. 1 is a schematic diagram showing the mechanical structure of the embodiment apparatus, FIG. 2 is a detailed view of the magnetic head 2 of FIG. 1, FIG. 3 is a block diagram showing the structure of a control circuit of the embodiment apparatus, and FIG. Two-dimensional actuator
FIG. 4 is a schematic view of 4 viewed from above.

This device is used by being mounted on a magneto-optical disk device of the magnetic field modulation type. As shown in the figure, the magneto-optical disk D 1 is accessed on the front surface side by the optical pickup 7 and the corresponding portion on the back surface side by the magnetic head 2. As a result, an external magnetic field whose direction is modulated according to the information is applied to the portion heated by the laser beam 8 output from the optical pickup 7 through the objective lens 9, and the magneto-optical disk D The above information is recorded for.

The above-mentioned magnetic head 2 includes support arms 6 and 2.
It is supported by the above-mentioned optical pickup 7 via a dimension actuator 4 and an arm 5. That is, from the optical pickup 7, a U-shaped support arm 6 is projected so as to bypass the set position of the magneto-optical disk D, and a two-dimensional actuator 4 is provided at the tip thereof. Installed. Further, an arm 5 is projected from the two-dimensional actuator 4, and a magnetic head 2 is attached to the tip of the arm 5.

The magnetic head 2 is an element comprising a coil 2b for magnetic field modulation on the peripheral surface of a core 2a. By controlling the current flowing through the coil 2b, the end surface for magnetic field application is formed.
The direction of the magnetic field generated vertically from 2c is controlled. The end face 2c of the magnetic head 2 is provided with a quadrant optical sensor 1 as shown in FIG. 2, and is set so that the centers of the sensor elements 1a to 1d coincide with the position where the vertical magnetic field is maximized. Has been done.

The two-dimensional actuator 4 is the above-mentioned actuator.
This is a member that controls movement of the lens 5 in two dimensions (T (tangential) direction, R (radial) direction, see FIG. 4). By this movement, the magnetic head 2 moves relative to the objective lens 9 on the optical pickup 7 side. The position is displaced. That is,
As shown in FIG. 4, the arm 5 is displaceably supported by support springs 4c attached to both side walls 4d of the two-dimensional actuator 4. Therefore, when the coil 4a is energized,
The arm 5 is displaced in the R direction, so that the magnetic head
2 is displaced in the radial direction of the magneto-optical disk D. Similarly, when the coil 4b is energized, the arm 5 is displaced in the T direction, whereby the magnetic head 2 is displaced in the circumferential direction of the magneto-optical disk D.

The energization of the coils 4a and 4b is controlled based on the output signals of the sensor elements 1a to 1d of the four-divided sensor 1. That is, as shown in FIG. 3, the sensor elements 1a, 1a
The output signal of c is input to the differential detector 11a, and its output signal is input to the driver 12a for driving the coil 4a. The output signals of the sensor elements 1b and 1d are differential detectors.
The signal is input to 11b, and its output signal is input to the driver 12b for driving the coil 4b. Therefore, when the laser beam 8a outputted from the optical pickup 7 and transmitted through the magneto-optical disk D is evenly applied to the sensor elements 1a to 1d as shown by the broken line 8b in FIG. The outputs of the differential detectors 11a and 11b both become 0, and the coils 4a and 4b
Is not energized. In other words, until the outputs of the differential detectors 11a and 11b both become 0, the coil 4
By energizing a and / or the coil 4b, the magnetic head 2 is two-dimensionally moved relative to the objective lens 9.

As described above, since the centers of the sensor elements 1a to 1d of the four-division optical sensor 1 are aligned with the maximum position of the vertical magnetic field of the magnetic head 2, the differential detectors 11a and 11b are arranged as described above.
As a result of controlling the output of the magnetic head to 0, the magnetic head 2
The optical axis of the laser beam 8a is aligned with the maximum position of the vertical magnetic field. Therefore, the magnetic field of the magnetic head 2 needs only a minimum magnetic field, and power consumption in the modulation circuit is also minimum.

[0016]

As described above, according to the present invention, a magneto-optical disk is used.
Since the laser beam transmitted only once is detected by the four-division optical sensor, it can be surely detected without being affected by noise. Further, by driving and controlling the actuator based on the detection signal to displace the magnetic head, the optical axis of the laser beam is aligned with the maximum position of the vertical magnetic field generated from the magnetic head. Therefore, the magnitude of the vertical magnetic field needs to be the minimum required magnitude, and the power consumption in the modulation circuit is also minimal.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a mechanical configuration of an apparatus of an embodiment.

FIG. 2 is a detailed view of the magnetic head 2 of FIG.

FIG. 3 is a block diagram showing a configuration of a control circuit of the embodiment apparatus.

4 is a schematic view of the two-dimensional actuator 4 of FIG. 1 viewed from above.

[Explanation of symbols]

 1 4-split optical sensor 2 Magnetic head

Claims (1)

[Claims] 1. A magnetic head comprising a core and a coil for magnetic field modulation, a four-division optical sensor provided on an end face of the magnetic head for applying a magnetic field, and an optical pickup with the four-division optical sensor sandwiching a magneto-optical disk. The actuator that supports the magnetic head so that it can be displaced two-dimensionally and the optical axis of the laser beam emitted from the optical pickup are opposed to the objective lens of
A control means for driving and controlling the actuator based on the output signal of the four-division optical sensor so as to match the maximum position of the vertical magnetic field from the end face for magnetic field application of the magnetic head to displace the magnetic head in two dimensions. A magnetic head positioning device having: