JPH04178980A - External magnetic field impressing device for magneto-optical recording device - Google Patents

Abstract

PURPOSE:To stably drive a displacement body by enabling an output corresponding to the distance from the surface of a magneto-optical recording medium to a floating member by means of a distance measuring element which is displaced together with an external magnetic field generating section in an integrated state while the floating member is maintained in a floating state at a fixed distance from the surface of a magneto-optical recording medium. CONSTITUTION:The first electrode plate 23 is provided on the upper surface of a slider member 9 and the second electrode plate 23 is provided on a displacement body 3 so that the plate 24 can be faced to the plate 23. Then the surface oscillation of a magneto-optical disk 2 is detected by detecting the volumetric variation produced between the plates 23 and 24 in accordance with the displacement of the member 9. Since the output voltage of a frequency- to-voltage converter can be changed in accordance wit the surface oscillation of the disk by means of an oscillator, the oscillation frequency of which changes in accordance with the volumetric variation, and the converter and the driving current supplied to a driving coil 7 is changed depending upon the output voltage of the converter, the displacement body 3 can be driven in accordance with the surface oscillation of the disk 2 and the interval between the leading end of an external magnetic field generating section 1 and the surface of the disk 2 can be maintained at a fixed level. Therefore, the displacement body 3 can be stably driven.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an external magnetic field applying device for a magneto-optical recording device that applies an external magnetic field to a magneto-optical recording medium.

(b) Conventional technology By applying an external magnetic field to a magneto-optical recording medium such as a magneto-optical disk and simultaneously irradiating a laser beam, only the area irradiated with the laser beam is magnetized according to the generated external magnetic field. However, a magneto-optical recording device that performs recording on a magneto-optical recording medium is known. As disclosed in, for example, Japanese Patent Application Laid-open No. 62-92148, a magneto-optical recording device uses a current in a magnetic field to displace an external magnetic field generating part that generates an external magnetic field in accordance with the surface runout of a magneto-optical recording medium. An external magnetic field applying device configured to maintain a constant distance between the magneto-optical recording medium and the external magnetic field generating section using a drive mechanism that drives the external magnetic field generating section using force generated by the flow. There are things with this.

By the way, in order to keep the distance between the magneto-optical recording medium and the external magnetic field generating section constant, it is necessary to detect the degree of change in the distance.As a method for this detection, for example, as shown in the above-mentioned publication, Similar to the focus control of a light beam of an optical pickup used in an optical disk device, etc., a light emitting element that generates a light beam and a light receiving element that receives reflected light reflected by a magneto-optical recording medium are used. It is known that this is done by detecting the difference in reflected light that is received.

(c) Problems to be Solved by the Invention However, the method that optically detects the change in the distance between the magneto-optical recording medium and the external magnetic field generating section using the reflected light described above does not detect the change in the distance between the magneto-optical recording medium and the external magnetic field generating part by using the change in the light intensity of the reflected light. Therefore, if the color of the magneto-optical recording medium is dark and the reflectance of light is low, it will not be possible to obtain enough reflected light to correctly detect the distance between the magneto-optical recording medium and the external magnetic field generator. In cases where the external magnetic field is applied from the label side of the magneto-optical recording medium, the distance cannot be detected correctly due to the difference in reflectance between the printed part and the other part. There wasn't.

On the other hand, as a magneto-optical recording medium using a magneto-optical disk as the magneto-optical recording medium, an external magnetic field generating part is attached to a floating head equipped with a slider part, as shown in, for example, Japanese Patent Laid-Open No. 2-56785. Some devices are equipped with an external magnetic field application device that levitates the floating head by using a floating blade generated in the floating head as a result of the airflow flowing when the disk is rotated.

However, such an external magnetic field applying device has an external magnetic field generating section attached to the floating head, and the weight of the external magnetic field generating section is added to the floating head, which is disadvantageous for making the floating head fly. If the speed at which the magneto-optical disk is rotated is slow, the floating head cannot be sufficiently floated.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and includes an external magnetic field generating section that generates an external magnetic field to be applied to a magneto-optical recording medium; a displacement body that is attached to the frame and is displaceably supported by the frame; a floating member that is supported by the frame so that it can float from the magneto-optical recording medium; and a floating member that is integrally displaced with the external magnetic field generating section and and a distance measuring element that generates an output according to the distance to measure the distance to the magneto-optical recording medium. The output signal is used to drive the displacement body.

(*) Effect The present invention levitates a levitation member at a substantially constant distance from the surface of a magneto-optical recording medium, and uses a distance measuring element that is displaced integrally with an external magnetic field generator to measure the distance to the levitation member according to the distance to the levitation member. This is so that the displacement body can be stably and correctly driven in accordance with the distance between the magneto-optical recording medium and the external magnetic field generating section without being affected by the surface of the magneto-optical recording medium.

Embodiment FIG. 1 is a schematic diagram showing an embodiment of the present invention, in which (L) is an external magnetic field generator that generates an external magnetic field to be applied to the magneto-optical disk (2), and (3) is an external magnetic field generator that generates an external magnetic field to be applied to the magneto-optical disk (2). A displacement body (6) to which a magnetic field generation part (1) is attached and supported by a disc-shaped butterfly damper (4) so as to be vertically displaceable on a frame (5) is wound with a drive filter (7), and the above-mentioned A bobbin (8) is fixed to the displacement body (3), a magnetic circuit is fixed to the frame (5), and (9) is a leaf spring for applying a magnetic field in a predetermined direction to the drive coil (7). A slider member (11) is elastically supported by the frame (5) by (10) and whose upper surface is made into a reflective surface by a white coating or the like.
) is a photocoupler consisting of a light emitting element that irradiates a light beam onto the upper surface of the slider member (9) and a light receiving element that receives reflected light from the upper surface of the slider member (9).

The external magnetic field generating part (↓) includes a circular yoke (12) with a protruding center and peripheral parts, and a field filter that can be wrapped in a donut shape to surround the center of the yoke (12). (13)
It generates a magnetic field according to the current flowing through the field filter (13), and the magnetic field is transmitted to the magneto-optical disk (2).
). Here, the magneto-optical disk (2) is locally irradiated with a laser beam generated from a laser beam generator (not shown), and the yoke of the external magnetic field generator (↓) is applied to a range including the irradiation point. (12) so that a magnetic field generated from the center is applied. Therefore, the irradiation point of the laser beam on the magneto-optical disk (2) can be magnetized according to the magnetic field generated from the center of the yoke (12). A current corresponding to the information to be recorded is passed through the field coil (13), so that signals are recorded on the magneto-optical disk (2) according to the information.

The magnetic circuit (β) also includes a yoke (14) fixed to the frame (5), a permanent magnet (15) with one magnetic pole surface adhered to the yoke (14), and the permanent magnet (15). and a center ball (16) adhered to the other magnetic pole surface of the yoke (14) and the center ball (16).
) A drive coil (7) is arranged within the magnetic gap formed between the two. Therefore, in order to keep the distance constant by supplying a signal corresponding to the distance between the tip end surface of the external magnetic field generating section (↓) and the surface of the magneto-optical disk (2) to the drive coil (7), the external The magnetic field generating section (1) can be driven.

By the way, the slider member (9) is configured such that its lower surface contacts the surface of the magneto-optical disk (2) when the magneto-optical disk (2) is not rotated by the leaf spring (10). The slider member (9) is formed into a tapered shape so that airflow generated on the surface of the magneto-optical disk (2) when the magneto-optical disk (2) is rotated flows downward. Therefore, when the magneto-optical disk (2) is rotated, the slider member (9) is
), a floating blade is generated. Here, since the force with which the slider member (9) is pressed against the surface of the magneto-optical disk (2) by its own weight and the plate spring (10) is appropriately set in advance according to the floating blade, the slider member (9) ) is rotated by the rotation of the magneto-optical disk (2).
2) It is stabilized in a state where it floats a predetermined distance above the surface.

On the other hand, a photocoupler (
A light beam emitted from 11) is irradiated.

Here, as shown in the schematic diagram of FIG. 2, the photocoupler (11) has a light emitting element (17) and a light receiving element (18) each having a predetermined angle with respect to the upper surface of the slider member (9). They are arranged side by side so as to face each other, and the light beam generated from the light emitting element (17) is reflected by the upper surface of the slider member (9) and then received by the light receiving element (18). ing.

By the way, when the position of the slider member (9) is displaced due to the surface runout of the magneto-optical disk (2>), the irradiation point of the light beam on the upper surface of the slider member (9) is displaced, as shown in FIG. (9) The optical axis of the reflected light reflected by the upper surface of the slider member (9) is displaced.
) is displaced upward, the optical axis of the reflected light received by the light receiving element (18) is displaced in the direction A, and conversely, the slider member (9
) is displaced downward, the optical axis of the reflected light received by the light receiving element (18) is displaced in the B direction. Therefore, depending on the degree of surface runout of the magneto-optical disk (2), the light receiving element (18)
) changes the degree of displacement of the light spot of the reflected light at the light receiving element (18), and the direction of displacement of the light spot of the reflected light at the light receiving element (18) changes in accordance with the direction of surface wobbling of the magneto-optical disk (2).

FIG. 3 is a model diagram of the interior of the light receiving element (18), in which resistors (19) are formed that are uniformly distributed in the moving direction of the light spot of reflected light. At the same time, currents generated at both ends of the resistor (19) are led out from the first and second output terminals (20) and (21). Then, currents that are inversely proportional to the resistance value R and R8 from the position P of the received light spot to each end of the resistor (19) flow toward the respective ends, and these currents flow toward the respective ends of the resistor (19). It is derived from the second output terminals (20) and (21). Therefore, the current value derived from the first output terminal (20) is
and the current value derived from the second output terminal (21) is I
, then each can be expressed as. However, ■ is an input current input from the input terminal (22) to the light receiving element (18).

Here, since the resistors (19) are uniformly distributed, the resistance values R and R8 are proportional to the length from the position P of the received light spot to each end of the resistor (19). Therefore, the first and second output terminals (20) and (
21), the position P of each received light spot is
A position signal whose current value changes according to the current value will be output. The slider member (9) is mounted on a magneto-optical disk (
The slider member (9) is displaced following the surface runout of (2).
) changes by a distance corresponding to a change in the position of the magneto-optical disk (2) surface. In addition, the light emitting element (17) is
The light receiving element (18) receives a stable amount of reflected light regardless of the reflectance of the magneto-optical disk (2) surface.

Therefore, the first and second output terminals (20) and (21
) The displacement body (3) can be driven to follow the surface runout of the magneto-optical disk (2) by supplying a drive signal corresponding to the position signal obtained from the drive coil (7) to the drive coil (7).
The distance between the tip of the external magnetic field generator (1) and the surface of the magneto-optical disk (2) can be kept constant.

FIG. 4 shows another embodiment of the invention. In this figure, the difference from FIG. 1 is that instead of making the upper surface of the slider member (9) a reflective surface, a first wide electrode plate (23) is provided on the upper surface of the slider member (9), and the displacement body (3) Instead of attaching the photocoupler (11) to the first electrode plate (23
) A second electrode plate (24) is provided on the displacement body (3) so as to face the second electrode plate (24). Then, according to the displacement of the slider member (9), the first and second electrode plates (23> and (24)
), and by detecting the capacitance change, the surface runout of the magneto-optical disk (2) is detected. In this case, for example, an oscillator whose oscillation frequency changes according to the capacitance change and a frequency/voltage converter which generates an output voltage according to the oscillation frequency of the oscillator are used to respond to the surface runout of the magneto-optical disk (2). so that the output voltage of the frequency/voltage converter changes, and the drive coil (7) is driven 1 according to the output voltage.
By supplying the fL flow, the displacement body (3) can be driven according to the surface runout of the magneto-optical disk (2), and the tip of the external magnetic field generator (↓) and the magneto-optical disk (2) can be driven. The distance from the surface can be maintained constant.

(G) Effects of the Invention As described above, according to the present invention, a distance measuring element is provided in which the floating member is levitated at a substantially constant distance from the surface of the magneto-optical recording medium and is displaced integrally with the external magnetic field generating section. Since the output is obtained according to the distance to the floating member, the displacement body can be driven stably without being affected by the surface of the magneto-optical recording medium, and the external magnetic field generating part can be used as the magneto-optical recording medium. It is possible to provide an external magnetic field application device that can maintain a constant distance and properly displace the magnetic field.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a model diagram of a photocoupler, and FIG. 3 is an explanatory diagram for explaining that output can be obtained according to the distance to the floating member. FIG. 4 is a sectional view showing another embodiment of the present invention. Explanation of main books (1)...external magnetic field generating part, (3)...displacement body,
(5) Frame, (9) Slider member (levitation member), (11) Photocoupler (distance measuring element), (23) (24) Electrode (distance measuring element) . Figure 1 Figure 2 Figure 3 Figure 45! I

Claims (1)

[Claims] (1) An external magnetic field generation section that generates an external magnetic field to be applied to the magneto-optical recording medium, a displacement body to which the external magnetic field generation section is attached and movably supported by a frame, and a displaceable body that can levitate from the magneto-optical recording medium. The levitation member includes a supported levitation member, and a distance measuring element that is displaced integrally with the external magnetic field generation unit and generates an output according to the distance to measure the distance to the levitation member. The magneto-optical recording device is characterized in that the displacement body is made to levitate substantially constant from the surface of the magneto-optical recording medium, and the displacement body is driven using an output signal generated from the distance measuring element. External magnetic field application device.