JPS6276004A - Bias magnetic field supply device for optomagnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain thin profile and momentary polarity changeover by arranging a rod shape permanent magnet along a moving orbit of an optical head in the radial direction of an optomagnetic disc face and combining a pinion rack gear mechanism and linear motor at its one end so as to form a rotary drive part for the polarity inversion. CONSTITUTION:A bias magnetic field supply rod permanent magnet 51 is arranged on the face opposite to a disc 2 corresponding to a moving line of an optical head 4. A rod permanent magnet 51 is turned by 180 deg. at the erasure mode and the polarity of the side facing the disc 2 is the S pole. In applying a DC current to a moving coil 67 of the linear motor in this case, the coil 67 is attracted while being guided to a center piece 651 against the energizing force of a spring 68 and a latching ring 654 is attracted and stopped by stopper magnets 656, 657. That is, a pinion gear 58 is turned by the movement of a rack gear 63 in this state and a latching ring 66 is stopped at the attracted position and the stop position of the moving coil is adjusted so that the polarity of the rod permanent magnet 51 is obtained accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bias magnetic field supply device used in a magneto-optical recording/reproducing apparatus for playing a magneto-optical disk that can be recorded, reproduced and erased.

(Prior Art) When performing recording, reproducing, and erasing operations on a magnetic disk, it is necessary to irradiate it with a laser beam and apply a bias magnetic field of a predetermined polarity to that point. In this case, the magnetic field applying means used an electromagnet or a permanent magnet. One using electromagnets is shown in FIG.

In FIG. 6, reference numeral 1 denotes a spindle motor that rotates the magneto-optical disk 2. In FIG. A U-shaped yoke 3 has a magneto-optical head 4 attached to its lower end and a coil 5 wound around its upper end to form an electromagnet.

The electromagnet generates a static magnetic field, and a direct current is passed through it so that the polarity is reversed during recording and reproducing and erasing. The original i+a head assembly, in which the original head 4 and the electromagnet are integrated, is moved in the directions of arrows A and B, that is, along the radial direction of the disk 2.

(Problems to be Solved by the Invention) The one shown in FIG. 6 has a problem in terms of efficiency because the magnetic circuit including the yoke 3 is an open loop, and the distance traveled by the yoke 3 is taken into account. This required a considerable amount of space, which was not desirable.

In addition, conventional magnets have a structure in which the polarity is changed by changing the rotation of a permanent magnet, but this tends to require a large mechanical shifting system, and is intended to also be used for changing the polarity.

(Means for Solving the Problems) The bias magnetic field supply device of the present invention includes a beam-like structure that extends from the outer periphery of the magneto-optical disk toward the center on the surface of the magneto-optical disk opposite to the surface where the original head is disposed. is placed,
At least one end of this beam body is supported at the outer periphery of the magneto-optical disk, and a bar-shaped permanent magnet for supplying a bias magnetic field is rotatably supported at both ends when placed upright at the center and outer periphery of the magneto-optical disk. A pinion gear is provided at one end of a bar-shaped permanent magnet for supplying a bias magnetic field on the outer circumferential side of the magneto-optical disk in correspondence with the movement line of the optical head, and a rack gear is arranged to mesh with the pinion gear,
A linear motor to which a moving coil is attached to one end of the rack gear attracts the rack gear to one end, and a biasing means attached to the other end of the rack gear attracts the rack gear to the other end when the moving coil is released from the linear motor. The magnet is operated to return to the end side, and is provided with rotation side means for limiting the rotation angle of the bar-shaped permanent magnet for bias magnetic field supply to 180 degrees in order to reverse the polarity of the bias magnetic field when the rack gear moves. It is characterized by

(Function) According to the present invention, magnetized bar-shaped permanent magnets are arranged in the radial direction of the magneto-optical disk, and a pinion, a rack gear, and a linear motor are used as the rotation mechanism for reversing the magnetic properties of the magneto-optical disk. Since the structure is thin, the movement space is small, and the fMi raw reversing mechanism using a linear motor is used, switching operations can be performed instantaneously.

(Example) Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows the exterior of the bias magnetic field supply device of the present invention, and FIGS. 2 to 4 show its main parts.

In the case of this invention, the optical head 4 is linearly moved in the radial direction on one side of the magneto-optical disk 2 by a moving means (not shown). Reference numeral 51 denotes a bar-shaped permanent magnet for supplying a bias magnetic field, which is arranged on the opposite surface of the disk 2 in correspondence with the movement line of the optical head 4. In this magnet 51, if the lower side facing the disk 2 is Nli, the upper side is S, and when it is rotated by the structure detailed in Figs. 2 to 4, the polarity is switched and the polarity is reversed. is now possible. The magnet 51 is further supported at both ends by beams 6 and suspended above the surface of the disk 2. The beam body 6 is supported at the outer periphery of the disk 2, and is arranged along the radial direction of the disk 2 so as to be able to hold the magnet 51 in an appropriate state. Furthermore, the beam body 6 can be rotated around the hinge shaft 610 to the position shown in the imaginary diagram 6' shown by the dashed line when replacing the desk 2, so that it does not get in trouble. As will be described later, 7 is a mechanism unit that rotates the magnet 51 to perform polarity reversal.

In FIGS. 2 to 4, 52 and 53 are caps fixed to both ends of the rod-shaped stone 51. A hole 54 is provided on the opposite side of the camp 52, into which the tip of a pivot shaft 55 is inserted to form a pivot bearing hole. The other end of the pivot shaft 55 is supported by the beam body 6 by a support piece 56. The oil power camp 53 has fins 57 on the outer periphery.
is provided, and one end of a pinion gear 58 is still fixed to the other side. A bearing hole 59 similar to the aforementioned bearing hole 54 is provided on the other end side of the pinion gear 58, into which the tip of the pivot shaft 60 is inserted. The other end of the pivot shaft 60 is supported by the beam body 6 by a support piece 61. 62 is
As will be described later, this is an adjustment screw that limits the rotation of the rod-shaped permanent magnet 51.

63 is a rack gear that meshes with the pinion gear 58. A moving coil 64 of a linear motor is attached to one end of the gear 63, and a recessed portion of the coil 64 is broken and guided by a center piece 651 of an E-shaped yoke 65 so that the moving coil 64 slides. Therefore, when the shape of the recessed portion of the coil 64 is cylindrical, the center piece 651 is formed in a cylindrical shape. Also, the other two pieces 652 of the yoke 65,
Permanent magnets 654 and 655 are fixed inside the magnet 658, and stopper magnets 656 and 6 made of biometal pieces are fixed therein.
57 is vignetted when attached. 66 is moving coil 6
This is a high magnetic permeability latching ring fixed to the opening side of the four parts of 4. 67 is the sawtooth shape tm of the rack gear 63
, m is a pinch roller arranged in knot contact with the smooth surface 7 on the opposite side. Other end of rack gear 63 1i
, a return spring 68 is attached that provides a biasing force for pulling out in a direction 71 opposite to the direction in which it is attracted by the linear motor.

Now, in the shape shown in FIG. 2, the upper side of the barrel-shaped Mizuku magnet 51 is SL, and therefore the side facing the disk 2 is N-shaped. This indicates the bias magnetic field in the recording/reproducing mode. At this time, the rack gear 63 is attracted by the spring 68 to the side opposite to the linear motor, and a rotational force is applied to the magnet 51 so that the fin 57 faces upward from the plane of the drawing. However, the rotation is regulated by the fin 57 coming into contact with the key 44 and the key 62, and the
It is adjusted and held so that it faces the surface of the

Next, in the erasing mode, the Mizuhisa Ibushi magnet 51 is set.

The polarity of the side facing the disk 2 needs to be S: ball. In this case, direct current is applied to the moving coil 67 of the linear motor. Then, the coil 67 is guided and attracted by the center piece 651 against the biasing force of the spring 68. Attracted moving coil 67
The latching ring 65.1 is the stopper magnet 656, 6.
57 absorbs the sound and stops, so even if the electricity is turned off, the current state is maintained. That is, this state is shown in FIG. 3 and FIG.
It stops at the position where 6 is attracted. At this time, the stopping position of the moving coil may be adjusted so that the polarity of the permanent wave stone 51 appears accurately.

To switch from the erase mode to the recording/reproducing mode, a current of the opposite polarity to that described above is applied to the moving coil 64 in a pulsed manner. Then, the repulsive force releases the latching ring 66 from its adsorption state, and then the rack gear 63 is pulled back by the return spring 68. Then, the pinion gear 58 rotates until the fan 57 hits the adjustment screw 62, thereby reversing the polarity.

In the embodiment described above, the stones 774, 656, 657 and the latching ring 654 form a self-holding means that utilizes the attraction force of a magnet. It may be a simple stopper, but it must be energized as shown in FIG. 5(b) during the erase mode. However, when the above-mentioned self-holding structure is used, as shown in FIG. 5(a), it is necessary to supply electricity in a pulsed manner only when switching modes, so energy loss is small and economical.

Further, in the above embodiment, the pivot shaft 55°60 is fixed to the support piece 56.59, and the cap 52°53911
Although a bearing hole is provided in I, rotation can be similarly facilitated by fixing the pivot shaft to the cap and providing bearing holes in the support pieces 56 and 59.

(Effects of the Invention) As described above, the present invention arranges a bar-shaped permanent magnet in the radial direction of the magneto-optical disk surface along the movement trajectory of the original head, and connects a pinion-rack gear mechanism and a linear motor at one end thereof. In combination, a rotary drive unit for polarity reversal is provided, and its structure can be made thinner than conventional ones, and the polarity switching operation can be performed instantaneously.

[Brief explanation of drawings]

FIG. 1 is a plan view of a main part of an embodiment of the present invention, which shows magneto-optical recording according to an embodiment of the present invention, FIG. 4 is a side view of the same embodiment, and FIG. 5 is an explanation of the operation of the same embodiment. The time chart shown in FIG. 6 is a front view of the conventional device. 2...Magneto-optical disk, 4...
・・・・・・・・・Former head, 7・・・・・・・・・
...Beam body, 51... Bar-shaped permanent magnet for bias magnetic field supply, 54, 59... Pivot bearing, 55, 60... Pivot shaft, 58... ......Pinion gear, 63...
・・・・・・・・・Rack gear, 64・・・・・・・
・・・・・・Moving coil, 65・・・・・・・・・
...Linear motor yoke, 68...
...Biasing means, 62.57.66.656.657...
...Rotation limiting means. Figure 4

Claims (6)

[Claims] (1) A magneto-optical disk is arranged along a direction from the outer periphery to the center of the magneto-optical disk on a surface opposite to the surface on which the optical head is arranged, and at least one end is supported at the outer periphery of the magneto-optical disk. a beam body, both ends of which are rotatably supported by the beam body at the center and outer periphery of the magneto-optical disk, and on the opposite surface of the magneto-optical disk corresponding to the line of movement of the optical head a pinion gear provided at one end of the rod-shaped permanent magnet on the outer peripheral side of the magneto-optical disk; a rack gear disposed to mesh with the pinion gear; and one end of the rack gear. a linear motor to which a moving coil is attached and which attracts the rack gear to one end; and a linear motor which is attached to the other end of the rack gear and which returns the rack gear to the other end when the moving coil is released from the linear motor. force means and
A bias magnetic field supply device for a magneto-optical recording device, characterized in that a rotation limiting means limits the rotation angle of the bar-shaped permanent magnet to 180 degrees when the rack gear moves to reverse the bias magnetic field polarity. (2) A bias magnetic field supply device for a magneto-optical recording/reproducing apparatus according to claim 1, wherein both ends of a bar-shaped permanent magnet for supplying a bias magnetic field are axially supported by a beam body by a pivot shaft. (3) A combination of a fin provided at the end of a rod-shaped permanent magnet for supplying a bias magnetic field and an adjustment screw that contacts this fin, and a latching magnetic ring provided at one end of the moving coil of the linear motor and attached to the yoke. 2. A bias magnetic field supply device for a magneto-optical recording/reproducing apparatus according to claim 1, wherein rotation limiting means is constituted by a combination of stopper magnets. (4) A bias of the magneto-optical recording/reproducing apparatus according to claim 1, wherein the magneto-optical recording disk is rotatably supported in an upward direction about a hinge shaft at an outer peripheral portion of the disk. Magnetic field supply device. (5) A combination of a fin provided at the end of a bar-shaped permanent magnet for supplying a bias magnetic field and an adjustment screw that contacts this fin, and a latching magnetic ring provided at one end of the moving coil of the linear motor and attached to the yoke. 3. The bias magnetic field supply device for a magneto-optical recording/reproducing apparatus according to claim 2, wherein the rotation limiting means is constituted by a combination of stopper magnets. (6) A bias magnetic field of a magneto-optical recording and reproducing apparatus according to claim 4, wherein the magneto-optical disk is rotatably supported in an upward direction about a hinge shaft at an outer peripheral portion of the disk. Feeding device.