JPH08255452A - Magnetic disk cartridge - Google Patents

Abstract

PURPOSE: To increase attraction force by a magnet to a center core and prevent the slip of revolution while obviating the generation of rotational vibrations by unbalanced load regarding the rotation at high speed of a magnetic disk for a cassette shell. CONSTITUTION: When a center core 31 is attracted by the magnets 14 for connection of a turntable 12 and revolved and driven in a magnetic disk 3 supported to a discoid center core 31 in a cassette shell 2, a magnetic head inserting port 6 is formed to the side face 23 of the cassette shell 2. A central hole 31a, into which the central positioning pin 13 of the turntable 12 is engaged, is formed at the central section of the center core 31 while an attracting section 31b having height different at a stepped shape from the place of the opening of the central hole 31a and being formed annularly is fitted to an outer circumferential section. The section 31b is attracted to the magnets 14 for connection annularly disposed on the outer circumferential side of the turntable 12 in a surface contacting manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk cartridge, and more particularly to a structure of a center core for supporting a central portion of a magnetic disk in a magnetic disk cartridge having a magnetic disk rotatably contained in a cassette shell.

[0002]

2. Description of the Related Art A magnetic disk cartridge is a thin cassette shell in which a magnetic disk for magnetically recording analog or digital signals is rotatably incorporated. The cassette shell has an upper surface slightly larger than the magnetic disk and a magnetic disk. Is formed into a flat prismatic shape (substantially square) having a bottom surface having an opening for exposing the center core supporting the center of the core and a narrow side surface extending between the top surface and the peripheral edge of the bottom surface. The magnetic disk cartridge is provided with a magnetic head insertion slot into / from which magnetic heads for magnetic recording / reproduction come in and out on both sides of the magnetic disk from the outside or come close to each other. An opening / closing shutter member is provided to prevent dust and the like from entering at the time.

[0003]

The magnetic head insertion port of the conventional magnetic disk cartridge is formed of elongated elongated rectangular openings extending in the radial direction of the magnetic disk on the top and bottom surfaces of the cassette shell.

By the way, the magnetic head insertion port does not necessarily have to be provided on the upper surface and the bottom surface of the cassette shell so as to extend in the radial direction of the magnetic disk, and the magnetic head contacts or approaches from the outside over the entire radius of both surfaces of the magnetic disk. Any shape that can be used,
It is desirable to make the opening as small as possible in order to prevent dust and the like from entering the cartridge. As the miniaturization of the magnetic head becomes possible, the magnetic head insertion port has more flexibility in its position and size, and from the above request, it is possible to provide it on only the side surface of the cassette shell instead of the top or bottom surface. Is coming. That is, on the narrow side surface of the cassette shell, a magnetic head insertion opening of a size that can be exposed from the outside is provided on both sides of the magnetic disk, and a thin arm-shaped pickup with a small magnetic head fixed at the tip is taken in and out from here. It has become possible to perform recording and reproduction while moving the magnetic disk in the radial direction.

In the magnetic disk cartridge having the magnetic head insertion opening on the side surface of the cassette shell as described above,
It becomes possible to incorporate a high-density and large-capacity magnetic disk. In such a magnetic disk, in order to increase the recording density and the transfer rate, it is necessary to rotate and drive the magnetic disk at a high speed of several thousand rotations for recording and reproducing like a conventional hard disk.

Also in the conventional thin magnetic disk cartridge, the central portion of the magnetic disk is supported by a center core made of a ferromagnetic metal plate member, and the center core is attracted to a magnet of a turntable and driven to rotate. Is provided. In addition, a square hole is formed in the center of the center core for the purpose of preventing eccentricity, and a square hole different from the square hole is opened in the outer peripheral portion.

On the other hand, in the case of rotating the magnetic disk at a high speed as described above, there should be no rotational deviation due to slip between the turntable and the magnetic disk at the time of starting rotation or during rotation, and the magnetic disk should be flat. It is necessary to rotate while maintaining sex.

However, if a square hole is opened at a position other than the center position as in the conventional magnetic disk cartridge in order to prevent the above-mentioned slippage, the unbalanced load lowers the weight balance of the rotating surface at high speed rotation and causes the rotational vibration. Will occur. From this point, in a magnetic disk cartridge that rotates at a high speed, it is preferable to suppress the vibration by using only the center hole as the center core hole. In this case, the rotational force of the turntable is transmitted only by the attractive force of the connecting magnet, and the slippage of the rotation tends to occur between the two at the time of starting the rotation or during the rotation.

In the conventional magnetic disk cartridge, in order to maintain the flatness at the time of rotation and improve the modulation, for example, as shown in Japanese Utility Model Laid-Open No. 61-24877, the contact surface of the center core is set to the center hole. It is known that the structure is made to dent inward, but in the center core of this structure, the contact with the magnet becomes a line contact, and if it rotates at high speed, the attraction force is insufficient and rotation deviation can occur. There is a nature.

In view of this point, the present invention solves the above-mentioned problem, that is, the center core of the magnetic disk is connected so as not to rotate and slide due to the attracting force of the connecting magnet of the turntable, and the vibration is reduced. It is an object of the present invention to provide a magnetic disk cartridge that can rotate at high speed.

[0011]

In a magnetic disk cartridge according to the present invention, a magnetic disk supported by a disk-shaped center core formed by a plate-shaped member is rotatably incorporated in a cassette shell, and the center core serves as a cassette shell. It faces the opening opened on the bottom and is driven to rotate by being attracted to the connecting magnet installed on the turntable.The cassette shell is slightly larger than the magnetic disk, and the upper surface is almost the same shape as this upper surface. It is formed into a flat prismatic shape consisting of parallel bottom surfaces and narrow side surfaces extending between the top surface and the peripheral edge of the bottom surface, and the magnetic recording / reproducing head is brought into contact with both sides of the magnetic disk from the outside on the side surfaces. Alternatively, there is provided a magnetic head insertion port for making them close to each other, and the center portion of the center core is a center with which the center positioning pin of the turntable is engaged. In addition to the above, the outer peripheral portion is provided with a ring-shaped attracting portion whose height is different stepwise from the opening position of the center hole, and the attracting portion is annularly disposed on the outer peripheral side of the turntable. It is characterized in that it is adsorbed by surface contact with.

[0012]

In the magnetic disk cartridge according to the present invention, the magnetic head insertion opening is provided on the side surface of the cassette shell, so that the magnetic head insertion opening can be made small and dust and the like can be prevented from entering the cartridge. It can be effectively prevented. Further, the center hole of the magnetic disk cartridge is provided with the center hole only at the center position, and the positioning pin of the turntable is engaged with the center hole to define the center of rotation of the magnetic disk. In addition, since no holes are opened, the rotational balance is good and the rotational vibration due to the unbalanced load is small even at high speed rotation, the modulation is small, and high-performance recording / reproducing can be performed.

Further, the rotation driving force of the turntable is transmitted by a connecting magnet attracted to the attraction portion of the center core. The attraction portion is formed on the outer peripheral side and the driving force by attraction with the annular coupling magnet is provided. Is efficiently transmitted and a large driving force is obtained, so that a rotational slip does not occur between the center core and the turntable even at the time of rotation start and during rotation, and good recording and reproduction can be performed by the magnetic head. Is. Furthermore, the suction part of the center core is formed in an annular shape with a stepped difference in height from the opening position of the center hole, positively escapes the part that you do not want to contact the connecting magnet, and securely sticks to the magnet. Can be seated, and further,
Due to the surface contact, a large attractive force can be obtained with the connecting magnet.

Particularly, in the center core, since the opening portion of the central hole and the suction portion are formed stepwise with different heights, the center core has high rigidity and little deformation due to external force, and the shape accuracy after processing is high. By maintaining it, the flatness of the attracting surface is good, the attracting area is large in the surface contact with the connecting magnet, a high attracting force can be secured, and the above-mentioned rotation deviation can be prevented satisfactorily. effective.

[0015]

Embodiments of the magnetic disk cartridge according to the present invention will be described below with reference to the accompanying drawings. 1 to 3 show an example of a magnetic disk cartridge according to the present invention. FIG. 1 is a top view of a shutter member in an open state, FIG. 2 is a perspective view of a bottom surface in a closed state, and FIG. 3 is a magnetic disk. FIG. 4 is a cross-sectional view showing the rotation holding state of

The cassette shell 2 in the magnetic disk cartridge 1 of the present embodiment has a magnetic disk 3 rotatably incorporated therein, and is formed by a pair of upper and lower cassette shell halves formed by plastic molding and divided into upper and lower halves. To be done. The cassette shell 2 has a substantially square upper surface 21 that is slightly larger than the built-in magnetic disk 3, a bottom surface 22 that is substantially the same shape as the upper surface 21 and is parallel to the upper surface 21, and a top surface 21 and a bottom surface 22.
Is formed into a flat prismatic shape having narrow side surfaces 23 extending between the peripheral edges of the.

The magnetic disk 3 (recording medium) is
The central portion is supported by the center core 31. The center core 31 is made of a ferromagnetic plate member formed into a disk shape by pressing or the like. The center core 31 has a circular opening 2a (see FIG. 2) formed on the bottom surface 22 of the cassette shell 2. It is arranged facing.

When the center core 31 is loaded in the magnetic recording / reproducing apparatus, as shown in FIG.
Are connected and driven to rotate at high speed. The turntable
12 is a positioning pin with a tapered tip at the center of rotation
13 is erected, and a chuck magnet 14 is annularly arranged on the outer peripheral side thereof.

The shape of the center core 31 is such that a center hole 31a with which the center positioning pin 13 of the turntable 12 is engaged is provided in the center portion, and a step shape is formed in the outer peripheral portion from the opening position of the center hole 31a. An adsorption portion 31b having different heights and formed in an annular shape and in a convex shape is provided. The attracting portion 31b is attracted by surface contact with the connecting magnet 14 annularly arranged on the outer peripheral side of the turntable 12.

A magnetic head insertion opening 6 is provided on one side surface 4 of the four side surfaces 23 of the cassette shell 2 for externally contacting or approaching the magnetic recording / reproducing head to both surfaces of the magnetic disk 3. Has been.

A shutter member 8 for opening and closing the magnetic head insertion opening 6 is slidably provided. The shutter member 8 includes an upper surface 21 and a side surface 23 of the cassette shell 2.
And a sleeve part 82 extending along the bottom surface 22 and a shutter part 82 and a lower sleeve part 83, which are connected in series in a U-shaped cross section, respectively, and move along each of the above-mentioned surfaces. The shutter portion 82 is provided with a shutter opening portion 82a that closes the magnetic head insertion opening 6 during storage and opens the magnetic head insertion opening 6 during operation.

On the other hand, in the cassette shell 2, the upper sleeve portion 81 of the shutter member 8 and the shutter portion are provided at the portions of the upper surface 21, the side surface 23 and the bottom surface 22 adjacent to the magnetic head insertion opening 6.
A shallow recess 9 is formed for receiving and guiding and holding 82 and lower sleeve 83.

The shutter member 8 is constantly urged in a direction to close the magnetic head insertion opening 6 by a shutter closing spring formed by a torsion spring (not shown). This shutter closing spring is inserted into the shell through a spring insertion opening 4a formed at one end of the side surface 4 of the cassette shell 2, and one end of the spring is provided at the side end of the shutter portion 82 of the shutter member 8. The other end of the engaging portion 82b is engaged with the inner surface of the shell.
The spring engaging portion 82b of the shutter member 8 passes through the sliding groove 4b provided on the side surface 4 of the cassette shell 2. The lower sleeve portion 83 of the shutter member 8 has guide claw portions 83a at two locations.
Is projected and engaged with a guide groove portion 22a formed along the sliding direction of the shutter member 8 on the bottom surface 22 of the cassette shell 2 to prevent the shutter member 8 from coming off.

In the above embodiment, when the magnetic disk cartridge 1 is used, the magnetic disk cartridge 1 in the state shown in FIG. 2 in which the shutter member 8 closes the magnetic head insertion opening 6 is magnetically operated as in the conventional magnetic disk cartridge. It is used by being loaded in a recording / reproducing device (hereinafter referred to as a device). At that time, according to the loading operation, the shutter member 8 is moved to the open position shown in FIG. 1 by the operation member provided on the apparatus side. When the magnetic disk cartridge 1 is taken out from the apparatus, the shutter member 8 is closed to the position shown in FIG. 2 in accordance with the taking-out operation such as pushing the operation button on the apparatus side.

There are various mechanisms on the device side for opening and closing the shutter member 8, and it is considered that its realization is as easy as that of the conventional device, so a detailed description thereof is omitted here. To do.

In response to the loading into the apparatus as described above, the turntable 12 is attached to the center core 31 exposed on the bottom surface 22 of the cassette shell 2 of the magnetic disk cartridge 1.
Move closer to each other. First, the tip of the positioning pin 13 of the turntable 12 engages with the center hole 31a of the center core 31 to position and regulate the center position of the center core 31, that is, the magnetic disk 3.
The magnetic attraction surface of the connecting magnet 14 on the outer peripheral portion of the magnetic disk 3 is magnetically attracted to the surface of the magnetic attraction portion 31b of the center core 31 in a surface contact state with a strong force, and the magnetic disk 3 rotates according to the rotation of the turntable 12. It is driven at high speed with little deviation in direction.

[Brief description of drawings]

FIG. 1 is a top side perspective view showing a state where a shutter member of a magnetic disk cartridge according to the present invention is opened.

FIG. 2 is a bottom side perspective view showing a state where a shutter member of the magnetic disk cartridge is closed.

FIG. 3 is a cross-sectional view of essential parts showing a rotation holding state of a magnetic disk.

[Explanation of symbols]

 1 magnetic disk cartridge 2 cassette shell 3 magnetic disk 4 side surface of cassette shell 6 magnetic head insertion opening 8 shutter member 12 turntable 13 positioning pin 14 connecting magnet 21 top surface of cassette shell 22 bottom surface of cassette shell 23 side surface of cassette shell 31 center Core 31a Center hole 31b Adsorption part 81 Upper sleeve part 82 Shutter part 82a Shutter opening part 83 Lower sleeve part

Claims (1)

[Claims] 1. A magnetic disk, the center portion of which is supported by a disk-shaped center core made of a ferromagnetic plate member, is rotatably incorporated in the cassette shell, and the center core is opened at the bottom surface of the cassette shell. In a magnetic disk cartridge that faces an opening and is driven to rotate by being attracted to a connecting magnet installed on a turntable, the cassette shell has an upper surface slightly larger than a magnetic disk, and a bottom surface that is substantially the same shape as this upper surface and is parallel to the upper surface. And a narrow side surface extending between the top and bottom edges and having a narrow width, and a magnetic recording / reproducing head is brought into contact with or close to both sides of the magnetic disk from the outside on the side surface. A magnetic head insertion opening for the purpose of providing a center hole for engaging the center positioning pin of the turntable in the center portion of the center core. At the same time, the outer peripheral portion is provided with a ring-shaped suction portion whose height is different stepwise from the opening position of the center hole, and the suction portion is connected to the outer periphery of the turntable in a ring shape for connection. A magnetic disk cartridge which is attracted to a magnet by surface contact.