JPH05325108A - External magnetic field generator - Google Patents

Abstract

PURPOSE:To prevent a sliding member from tilting or sliding on coarse surface on the outermost side of a magnetooptic disc even upon application of magnetic field on the outermost peripheral side of the magnetooptic disc. CONSTITUTION:The external field generator applies external field on a magnetooptic disk 205 in a recorder therefor, wherein a member 190 sliding on the magnetooptic disc 205 supports a field generating coil 194 at a position shifted to the outer peripheral side of the disc 205 and provided, on the central axis thereof, with a part in contact with the disc 205.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external magnetic field generator for applying an external magnetic field to a recording disk such as a magneto-optical disk when an information signal is recorded on the recording disk.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a recording / reproducing apparatus for recording / reproducing information signals by using a disc cartridge or the like which is constructed by accommodating a recording disc such as a so-called magneto-optical disc.

The above-mentioned magneto-optical disc has a disc substrate made of a transparent synthetic resin material and a signal recording layer made of a magnetic material adhered to one main surface of the disc substrate. There is. The writing of the information signal to the magneto-optical disk is performed by irradiating a predetermined portion of the signal recording layer with the condensed light flux and applying an external magnetic field. The irradiation of the light flux is performed through the disc substrate from the other main surface side of the disc substrate. Then, the application of the external magnetic field is performed from the main surface portion on one side of the disk substrate. The portion of the signal recording layer irradiated with the light flux loses its coercive force by being heated to a temperature higher than the so-called Curie temperature.
Then, the signal recording layer in the heated portion is magnetized in the direction following the direction of the external magnetic field in the process of cooling.

That is, in the magneto-optical disk, while rotating the magneto-optical disk, the light intensity of the luminous flux or the magnetic field intensity of the external magnetic field is modulated in accordance with the information signal, whereby the signal recording layer The information signal can be recorded depending on the magnetization direction.

A disk device for recording an information signal using such a magneto-optical disk has a rotating operation mechanism for holding and rotating the magneto-optical disk and an external magnetic field for applying an external magnetic field to the magneto-optical disk. A magnetic head, which is a generator, and an optical pickup device that collects and irradiates a light flux on the magneto-optical disk are configured.
The magnetic head and the optical pickup device are arranged so as to face each other via the magneto-optical disk. That is, the magnetic head and the optical pickup device are connected to each other via the magnetic head support arm. Further, the magnetic head and the optical pickup device are arranged along with the magnetic head support arm so as to be movable in the radial direction of the magneto-optical disk over the inner and outer circumferences of the magneto-optical disk.

The magnetic head has a magnetic core and a magnetic field generating coil wound around the magnetic core. The magnetic head is substantially in sliding contact with the signal recording layer via a thin synthetic resin layer such as a so-called protective layer or a slipping layer formed on the signal recording layer, oil or fat, etc. Is disposed in close proximity to. That is, the magnetic head is supported by the magnetic head support arm, the coil spring, and the like in a state of being pressed against the magneto-optical disk with a slight pressing force.

The above optical pickup device is constituted by including a light source such as a laser diode and an optical device for guiding and condensing a light beam emitted from this light source. In this optical pickup device, the focal length of the objective lens that focuses the light flux on the signal recording layer is so positioned that the focus point of the light flux is located on the boundary surface between the signal recording layer and the disk substrate. And are arranged at a distance substantially equal to.

In reading the information signal recorded on the magneto-optical disk in the recording and reproducing apparatus, the signal recording layer is irradiated with a condensed light beam in a linearly polarized state, and the signal recording of the light beam is performed. This is performed by detecting the polarization direction of the light flux reflected by the layer. That is, when the light flux is reflected by the surface portion of the signal recording layer, the polarization direction is changed by the so-called Kerr effect according to the magnetization direction of the signal recording layer. Therefore, the change in the magnetization direction of the signal recording layer can be read by detecting the polarization direction of the reflected light flux.

The detection of the reflected light flux is performed by an analyzer and a photodetector provided in the optical pickup device. This analyzer is a so-called Wollaston prism, a half-wave plate, or the like, and converts a difference in polarization direction into a change in light intensity. The photodetector is a photodiode, a phototransistor, or the like, and converts the light intensity of the received light flux into an electric signal.

[0010]

As described above, the magnetic head used as the external magnetic field generator in the recording / reproducing apparatus is used in sliding contact with the magneto-optical disk. This is to maintain the magnetic head at a constant height position with respect to the magneto-optical disk without using a mechanism for controlling the drive of the magnetic head in the height direction.

By the way, the protective layer and the slippery layer of the magneto-optical disk may have a non-uniform thickness or a roughened surface near the outermost periphery of the magneto-optical disk. .. Therefore, when the magnetic head slides in the vicinity of the outermost peripheral portion of the magneto-optical disk, the magnetic head may not be able to apply a stable magnetic field to the signal recording layer.

For example, this magneto-optical disk is set to 64 mm
In the case of being configured with a diameter of 32 mm (radius of 32 mm), a so-called program area formed within a range of a diameter of 61 mm (radius 30.5 mm) and a width of 0.5 mm on the outer peripheral side of this program area That is, the diameter is 61 mm to 62 mm (the radius is 30.5 mm to 31 mm).
mm) and a so-called lead-out area, which forms a signal recording area. Therefore, when recording an information signal up to the outermost periphery of the signal recording area, the magnetic head has a diameter of 62 m at the center of the generated magnetic field.
It is sent to a position formed on the circumference of m (radius 31 mm). At this time, the distance between this magnetic head and the outermost peripheral portion of the magneto-optical disk is only 1 mm. Within 1 mm from the outermost periphery of this magneto-optical disk,
In many cases, the thicknesses of the protective layer, the slipping layer, and the like are not uniform.

Therefore, conventionally, as shown in FIGS. 17 to 22, the sliding portion 390 slidably contacting the magneto-optical disk is displaced from the axial center of the magnetic coil 194 so that the signal recording area is A magnetic head has been proposed which prevents the sliding portion 390 from slidingly contacting the vicinity of the outermost peripheral portion of the magneto-optical disk even when a magnetic field is applied to the outermost peripheral portion.

In this magnetic head, the coil 1 is used.
94 indicates the magnetic core 19 as shown in FIGS. 17 and 18.
It is wound in 3. The magnetic core 193 is made of a high magnetic permeability material, and is provided with a core portion 193a and a pair of yoke portions that are continuous from the base end side of the core portion 193a and extend in parallel to both sides of the core portion 193a. Therefore, it is formed in a substantially E shape. The coil 194 has the core member 193.
It is wound around a. The magnetic core 193 around which the coil 104 is wound is, as shown in FIGS. 19 to 22, integrally formed with a substantially cylindrical shaft portion 392 and a substantially flange shape at the lower end side of the shaft portion 392. Sliding part 390 formed on the
The core member 193a is installed in a sliding member having a tongue and the tip of the core member 193a faces downward. The magnetic core 10
As shown in FIG. 22, 3 is housed in a coil-arranged void 399 formed on the lower end side of the shaft 392. The coil disposition void 399 is formed from the lower end side of the shaft portion 392 to the one side portion of the sliding portion 390.

In this magnetic head, the sliding portion 3
As shown in FIG. 22, 90 is a central axis 400 of the shaft portion.
The upper portion forms a part of the coil arrangement void portion 399 and is cut out.

In this magnetic head, the upper end of the shaft portion 392 is supported by a magnetic head support member (not shown), and as shown in FIG. 21, the sliding portion 392 is provided with a suspension spring 391 composed of a compression coil spring. Is supported by the magnetic head supporting member and slidably contacts the magneto-optical disk. At this time, the line of action of the pressing force on the magnetic head generated by the magnetic head support member and the suspension spring 391 coincides with the central axis 400 of the shaft portion 392. Therefore, in this magnetic head, the contact portion of the sliding portion 390 with respect to the magneto-optical disk does not exist on the line of action of the pressing force with respect to the magnetic head.

As described above, in the magnetic head in which the contact portion of the sliding portion 390 with respect to the magneto-optical disk does not exist on the line of action of the pressing force, the pressing force with respect to this magnetic head, the sliding portion 390 and the above The inclination easily occurs due to the frictional force between the magneto-optical disks and the like. When the magnetic head is tilted, the magnetic head is not slidably contacted with the magneto-optical disk in a certain state, and there is a possibility that the external self-harm cannot be properly applied to the magneto-optical disk.

Therefore, the present invention is proposed in view of the above-mentioned circumstances, and is an external magnetic field generator for applying an external magnetic field by sliding a magnetic head against a recording disk. Provided is an external magnetic field generation device capable of excellently applying an external magnetic field while preventing the magnetic head from tilting or vibrating even when a magnetic field is applied near the outermost periphery of a recording disk. The purpose is to do.

[0019]

In order to solve the above problems and to achieve the above objects, an external magnetic field generating device according to the present invention is provided with an elastic member which is pressed against a recording disk and at least pressed by the elastic member. A sliding member having an abutting portion for the recording disk on the line of action of, and a coil for generating a magnetic field attached to the sliding member, the coil having an axis serving as the center of the generated magnetic field, The position is offset from the line of action of the pressing force by the elastic member in the outer peripheral side direction of the recording disk.

[0020]

In the external magnetic field generator according to the present invention, even when the axis of the coil is positioned at the outermost peripheral portion of the signal recording area of the recording disk, the elastic member pushes against the sliding member supporting the coil. The line of action of pressure is located at a position deviated from the axial center of the coil toward the inner peripheral side of the recording disk. Therefore, when the shaft center of the coil is located at the outermost peripheral portion of the signal recording area of the recording disc, the sliding member does not need to contact the portion of the recording disc on the outer peripheral side of the shaft center. .. The sliding member has at least a contact portion for the recording disk on the line of action of the pressing force of the elastic member. Therefore, the sliding member does not tilt due to frictional force with the recording disk or vibration.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. This example is an example in which the external magnetic field generating device according to the present invention is applied to a recording / reproducing device for recording / reproducing information signals on / from a magneto-optical disk. In this recording / reproducing apparatus, a recording medium shown in FIG.
And a recording / reproducing disc cartridge 2 shown in FIG.
01 or the reproduction-only disc cartridge 211 shown in FIGS. 25 and 26 is selectively used.

The above-mentioned recording / reproducing disc cartridge 2
Reference numeral 01 is configured by rotatably storing a recording / reproducing disk 205 in a recording / reproducing cartridge 202. The recording / reproducing disk 205 is a so-called magneto-optical disk, and is a disk-shaped disk substrate made of a transparent synthetic resin or the like, and a signal made of a magnetic material adhered to one main surface of the disk substrate. And a recording layer. The disk substrate is formed to have a diameter of about 64 mm, for example.

A chucked portion is provided at the center of the disk substrate. This chucked part is
The disk substrate is composed of a circular through hole 217 and a metal plate 216 that closes the through hole 217. The through hole 217 of the chucked portion has its center aligned with the center of curvature of a recording track formed in a spiral shape having a substantially concentric shape in the signal recording layer.

An annular portion around the through hole 217 on the other main surface portion of the disk substrate is formed so as to project and serves as a positioning reference portion 223. Further, the metal plate 216 is fitted and disposed in a recess 218 provided around the through hole 217 in the main surface portion on one side of the disc substrate, and is disposed on the main surface portion on one side of the disc substrate. It is designed not to project.

The recording / playback cartridge 202 is
It is formed in a thin housing having a size capable of accommodating the recording / reproducing disk 205. An opening 203 for a magnetic head is formed in the main surface portion of the upper surface of the recording / reproducing / reading cartridge 202 so that the main surface portion on one side of the recording / reproducing / reading disk 205 faces the outer side over the inner and outer circumferences. ing. The recording / playback cartridge 20 is also used.
In the main surface portion on the lower surface side of 2, the recording / playback disc 2
An opening 215 for an optical pickup device is formed so that the other main surface of 05 is exposed to the outside along the inner and outer circumferences. The openings 203 and 215 are formed at positions facing each other and have substantially the same size and shape. That is, the openings 203 and 215 are located on the lateral sides of the main surface of the recording / reproducing cartridge 202 from the substantially central position thereof with respect to the mounting direction of the recording / reproducing disc cartridge 201 in the recording / reproducing apparatus. Is formed in a substantially rectangular shape over the vicinity of the side portion. Further, a chucking opening 219 for exposing the chucked portion and the positioning reference portion 223 to the outside is provided in the central portion of the main surface portion on the lower surface side of the recording / playback cartridge 202. There is.

The recording / playback cartridge 2 is also used.
A shutter member 204 for opening and closing the openings 203 and 215 is slidably attached to 02. The shutter member 204 is formed by bending a rectangular thin plate member made of synthetic resin, metal, or the like into a U shape, and the opening portions 203, 2 are formed by the side portions.
The lid 15 can be closed. This shutter member 2
Reference numeral 04 designates the central portion of the recording / playback cartridge 20.
It is supported by one side edge portion 2 so as to be slidable in the front-rear direction along the one side edge portion. This shutter member 204
Slides with respect to the recording / reproducing cartridge 202 to open and close the openings 203 and 215.

A shutter lid operating hole 207 for closing the shutter member 204 is provided in a central portion of the shutter member 204 supported by one side edge of the recording / reproducing cartridge 202. ing.

The recording / playback cartridge 20 is also used.
2 has a pair of front and rear positioning holes 22 in the main surface portion on the lower surface side.
0,221 are drilled. These positioning holes 22
Nos. 0 and 221 are adapted to position the recording / reproducing cartridge 202 with respect to the recording / reproducing unit of the recording / reproducing apparatus by inserting a positioning pin in the recording / reproducing apparatus. Then, at the position on the front end side of the bottom surface of the recording / reproducing / combining cartridge 202, the recording / reproducing / combining marking portion 2 which is a disc type marking portion
09 are provided. This recording / playback dual-purpose marking unit 209
Is a recess formed on the bottom surface of the recording / playback cartridge 202 with a very shallow depth of about 0.7 mm, for example.

Further, the recording / playback cartridge 2 is also used.
The shutter member 20 is provided on one edge of the shutter member 20 from the front end side.
A shutter opening groove 206 is provided over the central portion of No. 4. In the recording / reproducing apparatus, by inserting the shutter opening piece into the shutter opening groove 206 from the front side, the shutter member 204 is slid to the rear side of the recording / reproducing cartridge 202 and the opening portions are opened. The lids 203 and 215 are opened. A shutter supporting projection 208 is provided at a central portion of the shutter member 204 supported by one side edge of the recording / reproducing cartridge 202 so as to project forward along the shutter release groove 206. Has been done.

The recording / playback cartridge 20 is also used.
An erroneous insertion prevention groove 224 is provided from the front end side at the side edge portion of the other side opposite to the above one side edge portion of 2. In the erroneous insertion prevention groove 224, in the recording and reproducing device,
The incorrect insertion prevention piece is inserted from the front side.

On the other hand, the reproduction-only disk cartridge 211 is constructed by rotatably housing the reproduction-only disk 214 in the reproduction-only cartridge 212. The reproduction-only disc 214 has a disc-shaped disc substrate made of a transparent synthetic resin or the like, and a reflective layer made of a metal material adhered to one main surface portion of the disc substrate. There is. This read-only disc 214 is
It has the same size as the recording / playback disc 205. An information signal is recorded on the main surface portion of one side of the disc substrate of the reproduction-only disc 214 by forming fine irregularities by means such as injection molding. A chucked portion is provided at the center of the disc substrate. Like the chucked portion of the recording / playback disc 205, this chucked portion includes a circular through hole 217 formed in the disc substrate and a metal plate 216 that closes the through hole 217. It is configured.

The reproduction-only cartridge 212 is formed into a thin casing having a size capable of accommodating the reproduction-only disc 214. An opening 215 for an optical pickup device is formed in the lower main surface of the reproduction-only cartridge 212 so that the other main surface of the reproduction-only disc 214 faces the outer side over the inner and outer circumferences. There is. The opening 215 for the optical pickup device is located near the central portion of each main surface of the reproduction-only cartridge 212 and near the side of the reproduction-only disc cartridge 211 on the side with respect to the mounting direction in the recording and reproducing device. Is formed in a substantially rectangular shape. A chucking opening 219 for exposing the chucked portion and the positioning reference portion 223 to the outside is provided at the center of the lower main surface of the reproduction-only cartridge 212. ..

Then, the reproduction-only cartridge 212
A shutter member 213 for opening and closing the opening 215 for the optical pickup device is slidably attached to. The shutter member 213 is formed by bending one end side of a rectangular thin plate member made of synthetic resin, metal or the like, and has the opening 21 for the optical pickup device.
5 can be closed. This shutter member 21
The bent one end side portion is supported by one side edge portion of the reproduction-only cartridge 212 so as to be slidable in the front-back direction along the one side edge portion. The shutter member 213 slides with respect to the reproduction-only cartridge 212 to open and close the optical pickup device opening 215.

The shutter member 213 includes a shutter member 20 of the recording / reproducing disk cartridge 201.
4, the shutter closing operation hole 207 and the shutter supporting projection 208 are provided.

The reproduction-only cartridge 212 has a pair of front and rear positioning holes 220 and 221 and a shutter opening groove 2 in the same manner as the recording / reproduction cartridge 202.
06 and erroneous insertion prevention groove 224 are provided.

Then, this reproduction-only cartridge 212
At the position on the front end side of the bottom surface of the disc, a reproduction-only indicator 210, which is a disc type indicator, is provided. The reproduction-only marking section 210 is a recess that is formed deeper than the recording / reproducing and marking section 209 and has a depth of, for example, about 2.5 mm and is formed on the bottom surface of the reproduction-only cartridge 212.

The recording / reproducing apparatus having the external magnetic field generating device according to the present invention has the chassis 1 as shown in FIG. This chassis 1 is made of a metal plate material or the like, and is made up of a chassis bottom plate portion 2 and left and right side plates 3 and 2 which are mounted on both sides of the chassis bottom plate portion 2 so as to be substantially perpendicular to the chassis bottom plate portion 2. And a part 4 are formed.

On the chassis bottom plate portion 2 of the chassis 1,
Writing and reading of information signals to / from the recording / playback disc 205, or the playback-only disc 214.
A recording / reproducing unit 41 for reading the information signal is fixedly attached. As shown in FIG. 2, the recording / reproducing unit 41 is configured to have a base unit 57 attached to the chassis bottom plate unit 2. The base portion 57 faces the upper surface of the chassis bottom plate portion 2 through the cutout portion 5 provided in the chassis bottom plate portion 2 so as to cover substantially the entire upper surface portion. A spindle motor for rotating the disks 205 and 214 is attached to the base 57 at approximately the center. In this spindle motor, the drive shaft 67 is projected to the upper surface side of the base 57. A disc table 43 on which the discs 205 and 214 are placed is attached to the tip end side of the drive shaft 67. The disc table 43 is formed in a substantially disc shape, and is supported by the drive shaft 67 by fitting the drive shaft 67 into a support hole provided in the central portion.
On the upper surface side of the disc table 43, a centering portion 66 formed in a substantially truncated cone shape is provided in the central portion, and the peripheral side portion of the centering portion 66 serves as a disc mounting portion 65. This centering portion 66
Is formed to have an outer diameter that can be fitted into the through hole 217 of the chucked portion of each of the disks 205 and 214. The centering portion 66 is provided for each of the disks 20.
When the positioning reference portions 223 of 5, 214 are placed on the disc placing portion 65, the outer peripheral surface portion is provided with the through hole 2
The discs 205, 21 are brought into contact with the inner edge of
4. Centering is performed.

On the disc table 43, the metal plate 21 of the chucked portion of each disc 205, 214 is attached.
A magnet for attracting 6 is attached. With this magnet, the disk table 43 positions and holds the disks 205 and 214.

A pair of front and rear positioning pins 59 and 60 are erected on the base 57. The positioning pins 59, 60 are formed in a substantially spindle shape with the diameter of the tip end reduced. These positioning pins 59, 60
Fits into the positioning holes 220, 221 of the disk cartridges 201, 211 mounted on the base 57, and positions the cartridges 202, 212 with respect to the base 57.

Further, a pair of front and rear positioning projections 61 and 62 are planted on the base 57. These positioning protrusions 61 and 62 abut on the bottom surfaces of the respective disk cartridges 201 and 211 mounted on the base part 57, and the respective cartridges 2 with respect to the base part 57.
The positioning of the height position of 02,212 is performed.

On the base 57 of the recording / reproducing unit 41, the optical pickup device 42 can be moved in a direction of contacting with and separating from the disc table 43, as shown by an arrow C in FIGS. 1 and 2. Installed on.

The optical pickup device 42 has an optical block portion, and a light source such as a laser diode, a predetermined optical device for guiding a light beam emitted from the light source, and the disks 205, 214 are reflected in the optical block portion. In addition to having a built-in photodetector and the like for receiving the luminous flux, an objective lens driving device is attached to the optical block section. In this optical pickup device, the light flux emitted from the light source is emitted from the optical block portion and is incident on the objective lens 68 supported by the objective lens driving device. This objective lens 68
Collects the incident light flux. The objective lens driving device operates the objective lens 68 in two axial directions, that is, the optical axis direction of the objective lens and the direction orthogonal to the optical axis.

The optical pickup device 42 is supported by a pair of guide shafts 69 and 70 which are parallel to each other and mounted on the base 57, and can be moved in the axial direction of the guide shafts 69 and 70. Has been done. That is, the guide shafts 69 and 70 are inserted through the bearing holes formed in the optical block portion.

In the optical pickup device 42, the objective lens driving device faces the upper side of the base 57. In the optical pickup device 42, the optical axis of the objective lens 68 is perpendicular to the base 57, that is, perpendicular to the chassis bottom plate 2.

A magnetic head 45 is attached to the optical pickup device 42 via a connecting arm 73. As shown in FIG. 4, the connecting arm 73 is attached to the optical block portion of the optical pickup device 42 at the base end side and extends substantially parallel to the base portion 57, and has a magnetic end on the front end side. It has a rising bent piece portion 80 for supporting the head support block 44. The rising bent piece portion 80 is formed by bending the connecting arm 73 upward. The magnetic head support block 44
Is rotatably supported at its base end side by a support shaft 71 attached to the rising and bending piece portion 80, and extends from the rear side of the base 57 to the front side. By rotating the magnetic head support block 44 around the support shaft 71, the front end side, that is, the free end side, is moved to the base portion 5.
It is possible to make a displacement in a direction in which the movable body is brought into contact with and separated from 7.

A magnetic head support arm 58 is attached to the front end side of the magnetic head support block 44 so as to extend in the front direction. A magnetic head 45 is attached to the tip of the magnetic head support arm 58 on the side facing the base 57. The magnetic head 45 is held at a position facing the objective lens 68. That is, the magnetic head 45 is located on the optical axis of the objective lens 68 and can move in the direction of coming into contact with and separating from the objective lens 68.

The magnetic head support arm 58, as shown in FIGS. 8 and 9, is the magnetic head support block 44.
The frame body 179 is supported at the base end side thereof, and the leaf spring 180 serving as an elastic member is supported at the base end side of the frame body 179.

The frame 179 is formed of a material such as synthetic resin into a substantially elongated flat plate shape. This frame 179
Has a plurality of mounting holes 181 on the base end side, and is fixedly mounted on the magnetic head support block 44 via these mounting holes 181 by means such as screwing or fusion. The frame 179 has an opening from the midway portion to the tip side portion.

The leaf spring 180 is made of a material such as a thin metal plate and is formed into a substantially rectangular shape. This leaf spring 1
80 has a plurality of mounting holes on the base end side, and through a plurality of mounting bosses projecting in the middle part of the frame 179 through these mounting holes, by means such as fusion bonding, It is fixedly installed. The leaf spring 180 faces the inside of the opening from the middle portion to the tip side portion. The leaf spring 180 has a through hole 187 for preventing the occurrence of resonance.

A limiter member 189 is provided on the tip side of the frame 179. The limiter member 189 is located below the tip side portion of the leaf spring 180 and is integrally formed with the frame body 179. The limiter member 189 is provided with an insertion hole having a size into which the magnetic head 45 can be inserted.

The magnetic head 45 is inserted into the insertion hole of the limiter member 189 and is attached to the lower surface of the tip end side portion of the leaf spring 180. As shown in FIG. 9, the magnetic head 45 includes a coil 194 for generating a magnetic field.
And a sliding member to which the magnetic core 193 is attached. As shown in FIGS. 17 and 18, the magnetic core 193 is made of a high-permeability material and is continuously provided from a core portion 193a around which the coil 194 is wound and a base end side of the core portion 193a. It has a pair of yoke portions extending on both sides of the coil 194 and is formed in a substantially E shape. The sliding member is made of a material such as synthetic resin, as shown in FIGS. 13 to 16, and has a substantially cylindrical shaft portion 192 and the shaft portion 19.
2 has a sliding portion 190 integrally formed in a substantially flange-like shape on the lower end side of 2, and is integrally formed. The magnetic core 103 is placed inside the sliding member at a position below the shaft 192 with the tip of the core member 193a facing downward.

That is, the magnetic core 193 shown in FIG.
As shown in FIGS. 16 to 16, it is housed in a coil-arranged void 199 formed on the lower end side of the shaft 192. The coil disposition void 199 is formed from the lower end side of the shaft portion 192 to one side portion of the sliding portion 190.

In the magnetic head 45, the upper end of the shaft portion 192 of the sliding member is attached to the lower surface of the tip end side portion of the leaf spring 180, and the sliding portion 190 is attached to the limiter member 189. It is supported by being attached via a suspension spring 191 that serves as an elastic member.

In this magnetic head 45, as shown in FIG. 15, in the sliding portion 190, the portion on the central axis 200 of the shaft portion 192 is the coil disposing void portion 19.
The recording / playback disc 205 without being recorded within 9
Is an abutting portion that is slidably contacted with. In the magnetic head 45, the line of action of the pressing force exerted on the magnetic head 45 by the leaf spring 180 and the suspension spring 191 is the central axis 20 of the shaft portion 192.
It matches 0. Therefore, in the magnetic head 45, the contact portion of the sliding portion 190 with the recording / reproducing disk 205 exists on the line of action of the pressing force with respect to the magnetic head 45.

In the magnetic head 45,
The coil 194, as shown in FIG. 12 and FIG.
The center of the generated magnetic field is offset from the center axis 200 of the shaft portion 192 of the sliding member. When the recording / reproducing disk cartridge 201 is mounted on the base 57, the coil 194 has an axis centered on the central axis 200 of the shaft portion 192, that is, as shown in FIGS. Than the above line of action
It is supported by the magnetic head support arm 58 at a position offset toward the outer peripheral side of the recording / playback disk 205. Therefore, this magnetic head 45
10, even when a magnetic field is applied to the outermost peripheral portion of the signal recording area indicated by r ₂ in FIG.
0 does not come into sliding contact with the vicinity of the outermost peripheral portion of the recording / reproducing disk 205 indicated by an arrow r ₁ in FIG.

On the other hand, a torsion coil spring 74 is externally wound and attached to one end side portion of the support shaft 71 that supports the magnetic head support block 44. The torsion coil spring 74 is interposed between the connecting arm 73 and the magnetic head support block 44. The torsion coil spring 74 serves as the magnetic head support block 44.
Is urged to rotate in a direction in which the magnetic head 45 is separated from the objective lens 68. Therefore, in the initial state where the disk cartridges 201 and 211 are not mounted, the magnetic head support block 44 is
As shown in FIGS. 4 and 5, the magnetic head 45 is at an initial position separated from the objective lens 68.

Then, the magnetic head support block 44
A disc type detection arm 78 is attached to the disc. The disc type detection arm 78 is provided in the base 5
When the disc cartridges 201 and 211 are mounted on the disk 7, the front end side extending to the front side is provided with the recording / reproducing dual-purpose marking section 209 or the reproduction-only marking section 21.
It is pressed by the bottom surface of No. 0 and is rotated around the support shaft 71 together with the magnetic head support block 44.

A stopper arm 75 is disposed on the base 57 as shown in FIGS. 2 and 3. The stopper arm 75 is rotatably supported in the middle of the rear portion of the base 57 via a support shaft 77. The stopper arm 75 has a cartridge contact pin 76 on the upper surface on one end side. As shown by an arrow S in FIG. 2, the stopper arm 75 is urged by an urging member such as a coil spring (not shown) in a direction to move the cartridge contact pin 76 to the front side, and is moved to the initial position. It is positioned. At this time, the other end side portion of the stopper arm 75 is located below the tip end side portion of the disc type detection arm 78, that is, between the tip end side portion and the base portion 57. In this state, the disc type detection arm 78 is brought into contact with the stopper arm 75, so that the base portion 5 is
It is prevented from turning to the 7 side. That is, at this time, the magnetic head support block 44 is prevented from rotating in the direction of bringing the magnetic head 44 closer to the base 57 than the initial position, via the disk type detection arm 78.

Then, the cartridge contact pin 76
As shown in FIG. 3, when the disc cartridges 201 and 211 are mounted on the base portion 57, the disc cartridges 201 and 211 come into contact with the front end portions of the disc cartridges 201 and 211 and are moved to the rear side. As shown by the middle arrow T, the stopper arm 75 is rotated. At this time, the other end side portion of the stopper arm 75 is moved forward from the lower side of the tip end side portion of the disc type detection arm 78,
The restriction on the rotation of the disc type detection arm 78 is released.

When the recording / reproducing disk cartridge 201 is mounted on the base 57, the magnetic head support block 44 is provided with the disk type detecting arm 7 as described above.
8 is pressed by the bottom portion of the recording / reproducing / displaying portion 209 to rotate about the support shaft 71, and FIG.
As shown in, the magnetic head 45 is in the first position in which the magnetic head 45 is slidably contacted with the recording / reproducing disk 205. In addition, the magnetic head support block 44 is provided on the base 5
When the reproduction-only disc cartridge 211 is mounted on the disk 7, the contact protrusion 79 is attached to the reproduction-only marking portion 21.
6, the magnetic head 45 is moved toward the read-only disc 214 side relative to the initial position, as shown in FIG. The head 45 is located at a second position separated from the reproduction-only cartridge 212.

On the chassis bottom plate 2, as shown in FIG. 1, the disc cartridges 201,
A cartridge holder 26 for holding the disk cartridges 201 and 211 is provided by inserting 211 from the front side. The cartridge holder 26 is supported by the cartridge pressing plate 27. The cartridge pressing plate 27 is provided on the disk cartridge 20.
The main surface portions 1 and 211 have flat plate-shaped main surface portions having substantially the same size and shape, and side wall portions hanging from both sides of the main surface portion, and are formed of a metal plate or the like. The cartridge pressing plate 27 is arranged on the chassis bottom plate portion 2, and the rear side portions of the side wall portions are attached to the chassis bottom plate portion 2.
Is rotatably supported with respect to the chassis bottom plate portion 2
It is possible to approach and separate from. On the cartridge pressing plate 27, a plurality of leaf spring portions 27a for pressing and supporting the cartridges 202 and 212 downward are formed by cutting and raising.

The cartridge holder 26 has a housing-like shape having a size substantially corresponding to the cartridges 202 and 212 so that the cartridges 202 and 212 can be inserted from the front side. A part of the lower surface portion is formed to be open. The cartridge holder 26 is arranged on the lower surface side of the cartridge pressing plate 27 so as to extend substantially along the cartridge pressing plate 27, and both rear side portions can be pivoted to a middle portion of the cartridge pressing plate 27. Supported by. That is, the cartridge holder 26 can be brought into and out of contact with the cartridge pressing plate 27, and when the cartridge pressing plate 27 is rotated toward the chassis bottom plate portion 2 side, the cartridge pressing plate 2 is moved.
7 and the chassis bottom plate portion 2.

When the disc cartridges 201 and 211 are inserted into the cartridge holder 26 from the front side in a predetermined direction, the cartridge holder 26 is inserted.
The shutter opening piece provided inside is the shutter opening groove 2
Enter into 06. When the disk cartridges 201 and 211 are moved inward of the cartridge holder 26 and the shutter opening piece comes into contact with the front end portion of the shutter supporting projection 208, the cartridge holder 26 is provided. The shutter closing piece is fitted into the shutter closing operating hole 207. Then, when the disc cartridges 201 and 211 are further inserted into the cartridge holder 26, the shutter members 204 and 213 cause the front ends of the shutter supporting projections 208 to be the shutter opening pieces. Since it is stopped at the contacted position, the cartridge 20
2, 212 are slid with respect to each of the above-mentioned openings 20
Open the lids 3, 215.

A disc tray 30 is arranged on the chassis bottom plate 2. The disc tray 30 includes a receiving plate 39 on which the disc cartridges 201 and 211 are placed, and a frame portion that supports the receiving plate 39 so as to be vertically movable. The receiving plate 3
Reference numeral 9 has substantially the same shape and size as the main surface portions of the disk cartridges 201 and 211, and is formed of a thin metal plate or the like. The receiving plate 39 has a plurality of openings. These openings are formed on the receiving plate 3
When the disk cartridges 201 and 211 are placed on the disk 9,
No. 1 optical pickup device opening 215, chucking opening 219, positioning hole 220, each marking portion 20.
9, 210 and the like are made to face the lower side of the receiving plate 39.

The frame portion is made of a material such as a synthetic resin and has a linear portion located on the front end side of the receiving plate 39 and linear portions located on both sides of the receiving plate 39, and is substantially formed. It is formed to have a U-shape. That is, the frame portion is open on the rear side. The length of this frame portion in the front-rear direction is approximately twice the length of the main surface portion of the disk cartridges 201, 211 in the front-rear direction. The rear end side portions of both side portions of the frame portion are connected to each other via a connecting plate 31. The connecting plate 31 is made of a material such as a thin metal plate and is attached to the upper surface of the frame.

The frame portion supports the receiving plate 39 so as to be movable in the vertical direction. A pair of support pins 145, 146 are planted on both sides of the upper surface of the receiving plate 39. The support pins 145, 146 are fitted in a pair of support holes provided on both side portions of the frame portion from the lower side in a corresponding manner. The receiving plate 39 is movable in the up-down direction along the support holes 145, 146 along the support holes. This receiving plate 39 is
The front edge is near the front straight portion of the frame. The receiving plate 39 is elastically biased upward by a spring arranged in the frame portion.

The frame portion corresponds to both side portions of the disc cartridges 201 and 211 so that the disc cartridges 201 and 211 placed on the receiving plate 39 can be easily placed and taken out. At the position, a pair of cutouts 32 and 33 are provided to expose a part of both side portions of the disk cartridge 201 or 211 to the outside.

The disc tray 30 is arranged on the chassis bottom plate 2, and the disc cartridges 201, 211 mounted on the receiving plate 39 are recorded and reproduced by the recording and reproducing unit 41.
Above the disk and the disk cartridge 20
It is movable between the attachment / detachment operation positions of 1 and 211. That is, the guide member 34 is attached to one side portion of the frame body 30. This guide member 34
Is formed of a material such as a synthetic resin having a shaft insertion hole 35, is attached to the frame portion, and is projected in one side direction from the frame portion. The guide shaft 29 attached to the left side plate portion 3 is inserted into the shaft insertion hole 35 of the guide member 34. The guide shaft 29 has a front end side supported by a shaft support portion formed by bending a front end side portion of the left side plate portion 3 outward, and is provided at a rear end side portion of the left side plate portion 3. The rear end side is supported by the shaft support portion, extends in the front-rear direction, and is attached to the left side plate portion 3. A guide protrusion 139 is provided in the front-rear direction on the other side portion of the frame portion. The guide protrusion 139 is slidably supported on the upper side portion of the right side plate portion 2. The disc tray 30 is slidable in the front-rear direction along the guide shaft 29 and the guide protrusion 139.

This disc tray 30 is indicated by an arrow B in FIG.
Direction, the receiving plate 39 is set to the loading position which is the upper position of the recording / reproducing section 41, and when the receiving plate 39 is moved to the front side in the direction of arrow A in FIG. 39 is a position projecting to the front side of the chassis 1 and is an unloading position that enables the operation of attaching and detaching the disc cartridges 201 and 211 on the receiving plate 39.

The disc tray 30 is moved by a cam gear 28 which is rotated by a loading motor attached to the left side plate portion 3. The cam gear 28 is a gear in which the outer peripheral gear portion is formed on the outer peripheral side and the first cam groove is formed on one main surface portion. In the outer peripheral gear portion, a toothless portion which is approximately half the entire width of the outer peripheral gear is formed over an angular range of approximately 90 °.

On the other hand, on the bottom surface of the frame portion, the outer peripheral gear portion of the cam gear 28 is substantially half the entire width of the outer peripheral gear portion, that is, the portion corresponding to the portion where the toothless portion is formed. A rack gear that meshes with is formed. That is, when the cam gear 28 rotates, the frame portion is moved and operated within a rotation range of approximately 270 ° of the cam gear 28, that is, within a range in which the outer peripheral gear portion meshes with the rack gear. And this frame part
Within the rotation range of the cam gear 28 of about 90 °, that is, within the range where the toothless portion faces the rack gear, the movement operation is not performed.

The cam gear 28 is used not only for the disc tray 30 but also for the cartridge pressing plate 2.
Move 7 as well. The operation of moving the cartridge pressing plate 27 by the cam gear 28 is performed by rotating the toothless portion within an angle range of about 90 ° where the toothless portion faces the rack gear of the frame portion.

That is, the cartridge pressing plate 27
Is engaged with the first cam groove via a driven arm (not shown). That is, the cartridge pressing plate 27 is rotated with respect to the chassis bottom plate portion 2 when the cam gear 28 is rotated.

The chassis 1 is so-called floating-supported and attached to a supporting substrate 18 fixedly arranged in the outer casing of the recording and reproducing apparatus. That is, the chassis 1 corresponds to the support substrate 1
8 tension coil springs 6, 7, 8, 9
And four dampers 22, 23, 24, 25 are supported. These dampers 22, 23, 24, 25 are
A liquid material having a high viscosity is enclosed in a bag-shaped member made of a flexible material such as rubber.

In the recording / reproducing apparatus having the external magnetic field generator according to the present invention as described above, first, the recording / reproducing disc cartridge 201 or the reproduction-only disc cartridge 211 is mounted. The disc tray 30 is set to the unloading position. At this time, the cartridge pressing plate 27 is held at a position separated from the chassis bottom plate portion 2, and the cartridge holder 26 is separated from the chassis bottom plate portion 2. In this state, the disc cartridges 201 and 211 are placed on the receiving plate 39.

When the cam gear 28 starts to rotate by the loading motor, the disc tray 30 is moved to the rear side as shown by an arrow B in FIG. When the disc tray is moved further rearward, the disc cartridges 201, 21
1 is inserted into the cartridge holder 26 from the front side. Then, the disk cartridges 201, 2
11, the shutter members 204 and 213 are
The shutter opening piece allows the cartridge 202,
The optical pickup device opening 215 or the magnetic head opening 203 is moved with respect to 212.
Then, the opening 215 for the optical pickup device is opened. At this time, the shutter closing piece is fitted into the shutter closing operating hole 207. Until this time,
As shown in FIGS. 4 and 5, the magnetic head support block 44 is at an initial position for holding the magnetic head device 45 in the raised position.

When the disc tray 30 reaches the loading position, the toothless portion faces the rack gear of the disc tray, and even if the cam gear 28 further rotates, the disc tray 30 remains stopped. Maintained. At this time, the disc cartridge 201,
As shown in FIG. 5, 211 is conveyed to a position above the recording / reproducing unit 41. At this time, the arrow U in FIG.
The space between the bottom surfaces of the disk cartridges 201 and 211 and the disk table 43 shown by is a sufficient distance of, for example, about 4 mm.

When the cam gear 28 further rotates, the cartridge pressing plate 27 is rotated by the first cam groove to the side closer to the chassis bottom plate portion 2. Then, the disk cartridges 201, 21
As shown in FIG. 6 and FIG.
It is mounted and mounted on the base part 57, and the loading operation is completed. These disk cartridges 201,
211 is elastically pressed and supported by the leaf spring portions 27a of the cartridge pressing plate 27 on the side of the base portion 57. The receiving plate 39 is pressed by the disc cartridges 201 and 211 and moved downward with respect to the frame portion. The cartridges 202 and 21
2 is positioned at a predetermined position on the base 57 by the positioning pins 59, 60 and the positioning protrusions 61, 62.

The magnetic head support block 44
When the recording / playback disc cartridge 201 is mounted, as shown in FIG.
Playback-only disc cartridge 2
When 11 is attached, as shown in FIG.
The first position is set. In addition, each of the above disks 20
5, 214 are positioned and mounted on the disc table 43. At this time, the spindle motor can rotate the disks 205 and 214 together with the disk table 43.

In the case where the recording / playback disc cartridge 201 is mounted on the base 57,
As shown in FIGS. 10 to 12, the magnetic head 45 places the lower surface portion of the sliding portion 190 on one main surface portion of the recording / playback disk 205. When the recording / reproducing disk 205 is rotated by the spindle motor and the recording / reproducing disk 205 moves relative to the magnetic head 45, the magnetic head 45 causes the sliding portion 190 to perform the recording / reproducing operation. The disc 205 is brought into sliding contact with one main surface portion. At this time,
The leaf spring 180 presses the magnetic head 45 against the recording / reproducing disk 205 with an appropriate pressing force. In addition, the suspension spring 191
Is the magnetic head 4 due to fine unevenness caused by dust or damage on the main surface of the recording / reproducing disk 205.
Absorb the vibration of 5. At this time, the sliding member has an abutting portion for the recording / reproducing disk 205 on the line of action of the pressing force by the leaf spring 180 and the suspension spring 191, so that the sliding member is in contact with the recording / reproducing disk 205. Inclination does not occur due to frictional force between them or vibration.

In this state, in the optical pickup device 42, the objective lens 68 is opposed to the main surface portion on the other side of the recording / reproducing disk 205 or the reproduction-only disk 214. In addition, the optical pickup device 42 includes the disks 205,
The objective lens 68 can be moved over the inner and outer circumferences of the disks 205 and 214 while the objective lens 68 is opposed to the disk 214. The optical pickup device 42 is capable of irradiating each of the disks 205 and 214 with a light beam from the other main surface side. The optical pickup device 42 includes the disks 205, 21.
When the disc type detection arm 78 is moved in the radial direction over the inner and outer peripheries of 4, the movement of the support shaft 71 in the axial direction is blocked by the base portion 57, and remains at a fixed position. At this time, the support shaft 71 and the rotation restricting shaft 72 are moved together with the magnetic head support block 44 and slide in the axial direction with respect to the disc type detection arm 78.

By operating the spindle motor, the optical pickup device 42, and the magnetic head device 45, the recording / reproducing disk 205 is also used.
It is possible to write an information signal to. That is, the recording / playback disc 205 is rotated, and the signal recording layer of the recording / playback disc 205 is focused by the optical pickup device 42 to irradiate the luminous flux to heat the illuminated area, which is then heated. The magnetic head device 45 applies an external magnetic field to the portion to write the information signal. In this state, the information signal can be read from the reproduction-only disc 214. That is, the reproduction-only disc 214 is rotated, and the optical pickup device 42 collects and irradiates the luminous flux on the reflective layer.
The information signal is read by detecting the reflected light flux of the light flux.

Then, in order to take out the respective disk cartridges 201 and 211 mounted in the recording / reproducing section as described above from the recording / reproducing apparatus, the cam gear 28 is used.
Is rotated in the reverse direction of the loading operation described above, and is rotated in the direction in which the disc tray is transferred to the front side. Then, the cartridge pressing plate 27 is rotated in a direction away from the chassis bottom plate portion 2, and the cartridge holder 26 is moved to the upper side of the chassis bottom plate portion 2. At this time, the disc cartridge 20
The reference numerals 1 and 211 are separated from the base 57 of the recording / reproducing unit 41 and placed on the receiving plate 39. Further, the magnetic head support block 44 returns to the initial position by the biasing force of the torsion coil spring 74, as shown in FIG. At this time, the magnetic head 45 moves downward with respect to the frame body 179 together with the tip side portion of the leaf spring 180, but the limiter member 189 contacts the tip side portion of the leaf spring 180. , This leaf spring 18
Prevent excessive deviation of zero.

When the cam gear 28 is further rotated, the disc tray 30 is moved forward. At this time, the disc cartridges 201 and 211 are conveyed forward while being placed on the receiving plate 39. At this time, in the disc cartridges 201 and 211, the shutter closing pieces are used to close the shutter members 204 and 213. Further, the cam gear 28 is rotated,
When the disc tray 30 reaches the unloading position, the disc cartridges 201 and 211 are
It can be removed from the disc tray 30.

[0086]

As described above, in the external magnetic field generator according to the present invention, even when the axial center of the coil is located at the outermost peripheral portion of the signal recording area of the recording disk, the slider for supporting the coil is provided. The line of action of the pressing force exerted by the elastic member on the moving member is at a position deviated from the axial center of the coil toward the inner peripheral side of the recording disk. Therefore, when the shaft center of the coil is located at the outermost peripheral portion of the signal recording area of the recording disc, the sliding member does not need to contact the portion of the recording disc on the outer peripheral side of the shaft center. ..

The sliding member has at least a contact portion for the recording disk on the line of action of the pressing force of the elastic member. Therefore, the sliding member does not tilt due to frictional force with the recording disk or vibration.

That is, the present invention is an external magnetic field generator for applying an external magnetic field by sliding a magnetic head against a recording disk, and when applying the magnetic field to the vicinity of the outermost periphery of the recording disk. Even if there is, it is possible to provide an external magnetic field generator that prevents the magnetic head from tilting, vibrates, or the like, and can favorably apply an external magnetic field.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a recording and reproducing apparatus configured using an external magnetic field generating apparatus according to the present invention.

FIG. 2 is a plan view showing a configuration of a recording / reproducing unit of the recording / reproducing apparatus.

FIG. 3 is a plan view showing a state in which a disc cartridge is mounted on the recording / reproducing unit.

FIG. 4 is a side view showing a configuration of the recording / reproducing unit and a disc cartridge mounted in the recording / reproducing unit.

FIG. 5 is a side view showing a state in which the disc cartridge is being mounted in the recording / reproducing unit.

FIG. 6 is a side view showing a state in which a read-only disc cartridge is mounted in the recording / playback unit.

FIG. 7 is a side view showing a state in which a recording / reproducing disk cartridge is mounted in the recording / reproducing unit.

FIG. 8 is an enlarged plan view showing a configuration of a main part of the external magnetic field generator according to the present invention.

FIG. 9 is an enlarged side view showing a configuration of a main part of the external magnetic field generator.

FIG. 10 is an enlarged plan view showing a state where the external magnetic field generator is slid on the recording disk of the disk cartridge.

FIG. 11 is an enlarged side view showing a state where the external magnetic field generator is slid on the recording disk of the disk cartridge.

FIG. 12 is an enlarged side view showing a state of the magnetic head when the external magnetic field generator is slid on the recording disk of the disk cartridge.

FIG. 13 is an enlarged plan view showing a configuration of a main part of a magnetic head that constitutes the external magnetic field generator.

FIG. 14 is an enlarged side view showing a configuration of a main part of a magnetic head that constitutes the external magnetic field generation device.

FIG. 15 is an enlarged bottom view showing a configuration of a main part of a magnetic head that constitutes the external magnetic field generator.

FIG. 16 is an enlarged vertical cross-sectional view showing a configuration of a main part of a magnetic head that constitutes the external magnetic field generation device.

FIG. 17 is an enlarged side view showing a magnetic core forming the magnetic head.

FIG. 18 is an enlarged bottom view showing the magnetic core.

FIG. 19 is an enlarged vertical cross-sectional view showing a configuration of a main part of a magnetic head that constitutes a conventional external magnetic field generator.

FIG. 20 is an enlarged plan view showing a configuration of a main part of a magnetic head that constitutes the conventional external magnetic field generation device.

FIG. 21 is an enlarged side view showing a configuration of a main part of a magnetic head that constitutes the conventional external magnetic field generation device.

FIG. 22 is an enlarged bottom view showing the configuration of the main part of the magnetic head that constitutes the conventional external magnetic field generation device.

FIG. 23 is a perspective view showing the structure of a disk cartridge for both recording and reproduction.

FIG. 24 is a perspective view of the disk cartridge for both recording and reproduction as viewed from the bottom surface side.

FIG. 25 is a perspective view showing the structure of a reproduction-only disc cartridge.

FIG. 26 is a perspective view of the reproduction-only disc cartridge as viewed from the bottom side.

[Explanation of reference numerals] 45 ... Magnetic head 58 ..... Magnetic head support arm 179 ..... Frame body 180 .....・ ・ ・ ・ ・ ・ ・ ・ Leaf spring 190 ・ ・ ・ ・ ・ ・ ・ ・ Sliding part 191 ・ ・ ・・ ・ ・ ・ Suspension spring 192 ・ ・ ・ ・ Shaft 193 ・ ・・ ・ ・ ・ Magnetic core 193a ・ ・ Core material 194 ..... coil

Claims (1)

[Claims] 1. A sliding member, which is pressed against a recording disk by an elastic member, and has at least an abutting portion for the recording disk on the line of action of the pressing force by the elastic member; and a sliding member attached to the sliding member. And a coil for generating a magnetic field, wherein the coil has a shaft center which is the center of the generated magnetic field and is located at a position displaced from the line of action of the pressing force by the elastic member toward the outer peripheral side of the recording disk. External magnetic field generator.