JP3480758B2 - Magnetic disk cartridge - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supports a magnetic disk cartridge, and more particularly, a magnetic disk cartridge in which a magnetic disk is rotatably incorporated in a cassette shell. It relates to the structure of the center core. 2. Description of the Related Art A magnetic disk cartridge has a thin cassette shell in which a magnetic disk for magnetically recording analog and digital signals is rotatably incorporated. The cassette shell has an upper surface slightly larger than the magnetic disk. And a flat prismatic (substantially square) shape having a bottom surface having an opening exposing a center core supporting the center of the magnetic disk, and a narrow side surface extending between the top surface and the periphery of the bottom surface. ing. The magnetic disk cartridge is provided with a magnetic head insertion slot through which magnetic heads for magnetic recording and reproduction are brought into and out of the magnetic disk from both sides to come into contact with or approach from outside, and this magnetic head insertion slot is not used. An opening / closing shutter member is provided to prevent intrusion of dust or the like at the time. [0003] The magnetic head insertion opening of the conventional magnetic disk cartridge is formed of an elongated, substantially rectangular opening extending in the radial direction of the magnetic disk on the top and bottom surfaces of the cassette shell. The magnetic head insertion opening does not necessarily need to be provided on the top and bottom surfaces of the cassette shell so as to extend in the radial direction of the magnetic disk. It can be anywhere as long as it is possible,
In order to prevent dust and the like from entering the cartridge, it is desirable to make the opening as small as possible. As the size of the magnetic head can be reduced, the degree of freedom of the position and size of the magnetic head insertion opening increases, and from the above-mentioned request, the magnetic head insertion opening can be provided only on the side surface of the cassette shell, not on the top surface or the bottom surface. Are coming. In other words, a magnetic head insertion slot is provided on the narrow side surface of the cassette shell so that both sides of the magnetic disk can be seen from the outside, and a thin arm-shaped pickup with a small magnetic head fixed at the tip is inserted in and out from here. It has become possible to perform recording and reproduction while moving the magnetic disk in the radial direction. [0005] As described above, in the magnetic disk cartridge provided with the magnetic head insertion port on the side surface of the cassette shell,
A high-density, large-capacity magnetic disk can be built in. In order to increase the recording density and the transfer rate of such a magnetic disk, it is necessary to rotate and drive the magnetic disk at a high speed of several thousand rotations as in a conventional hard disk to perform recording and reproduction. In the conventional thin magnetic disk cartridge, the center 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. It is provided so that. The center core is provided with a square hole at the center and another square hole at the outer periphery for the purpose of preventing eccentricity. On the other hand, when the magnetic disk is rotated at a high speed as described above, there must be no deviation in rotation due to slip between the turntable and the magnetic disk at the start of rotation or during rotation. It is necessary to rotate while maintaining the nature. However, if a square hole is opened at a position other than the center position as in a conventional magnetic disk cartridge in order to prevent the above-mentioned slippage, the weight balance of the rotating surface during high-speed rotation is reduced due to the uneven load, and the rotational vibration is reduced. Will occur. From this point, in a magnetic disk cartridge that rotates at a high speed, it is preferable to suppress vibration by using only the center hole as the center hole. In this case, the rotation force of the turntable is transmitted only by the attraction force of the coupling magnet, and rotation slippage is likely to occur between the two at the start of rotation or during rotation as described above. In the conventional magnetic disk cartridge, in order to maintain the flatness during rotation and improve the modulation, the contact surface of the center core is formed in the center hole as shown in, for example, Japanese Utility Model Laid-Open No. 24877/1986. It is known that the center core of this structure has a linear contact with the magnet. There is. 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 cause rotational slip by the attraction force of the connecting magnet of the turntable, and the vibration is reduced in a state where vibration is small. It is an object of the present invention to provide a magnetic disk cartridge capable of rotating at high speed. A magnetic disk cartridge according to the present invention is capable of rotating a magnetic disk whose center is supported by a disk-shaped center core made of a ferromagnetic plate member in a cassette shell. The center core faces the opening that opens to the bottom surface of the cassette shell, is attracted to the connecting magnets installed on the turntable, and is driven to rotate, and the cassette shell is slightly larger than the magnetic disk. The upper surface is formed in a flat prismatic shape having substantially the same shape as the upper surface and a bottom surface parallel to the upper surface and a narrow side surface extending between the upper surface and the periphery of the bottom surface. A magnetic head insertion slot is provided for externally contacting or bringing the head into contact with both surfaces of the magnetic disk, and a turntable is provided at the center of the center core. Only the center hole into which the center positioning pin is engaged is provided, and the center positioning pin of the center hole is inserted in the outer peripheral portion.
An annular suction portion having a height different from the opening position on the entrance side is provided in a stepped manner, and the suction portion is attracted by surface contact to a connecting magnet arranged annularly on the outer peripheral side of the turntable. It is characterized by the following. In the magnetic disk cartridge according to the present invention, since the magnetic head insertion opening is provided on the side surface of the cassette shell, the magnetic head insertion opening can be made small, and dust and the like enter the cartridge. Can be effectively prevented. In addition, since the center hole of the center core of the magnetic disk cartridge is provided only at the center position, the positioning pin of the turntable is engaged with the center hole, and the rotation center of the magnetic disk is defined. In addition, since no holes are formed, the rotation balance is good, and even at high speed rotation, the occurrence of rotational vibration due to the unbalanced load is small, the modulation is small, and high-performance recording and reproduction can be performed. The rotation driving force of the turntable is transmitted by a connecting magnet that is attracted to the attracting portion of the center core. The attracting portion is formed on the outer peripheral side and is driven by the attracting force with the annular connecting magnet. Is efficiently transmitted and a large driving force is obtained, so that no rotational slip occurs between the center core and the turntable even during rotation start-up and rotation, and good recording / reproduction with a magnetic head can be performed. It is. In addition, the suction part of the center core is formed in an annular shape with a stepped height different from the opening position of the center hole, and the part that you do not want to contact with the connecting magnet is actively escaped, and it is securely attracted to the magnet Can be seated,
Due to the surface contact, a large attractive force can be obtained with the connecting magnet. In particular, since the center core is formed such that the opening portion of the center hole and the suction portion are formed stepwise with different heights, the rigidity is high, the deformation against external force is small, and the shape accuracy after processing is high. By maintaining this, the flatness of the attraction surface is good, the attraction area in surface contact with the connecting magnet is large, a high attraction force can be secured, and the rotation deviation as described above can be prevented well. effective. An embodiment of a magnetic disk cartridge according to the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 3 show an example of a magnetic disk cartridge according to the present invention. FIG. 1 is a perspective view of an upper surface side with a shutter member opened, FIG. 2 is a perspective view of a bottom side with a shutter member closed, and FIG. FIG. 4 is a cross-sectional view showing the rotation holding state of FIG. The cassette shell 2 in the magnetic disk cartridge 1 of the present embodiment has a magnetic disk 3 rotatably built therein, and is formed of a pair of upper and lower cassette shell halves formed by plastic molding and divided into upper and lower parts. Is done. The cassette shell 2 has a substantially square upper surface 21 slightly larger than the built-in magnetic disk 3, a bottom surface 22 having substantially the same shape as the upper surface 21 and parallel to the upper surface 21, and a top surface 21 and a bottom surface 22.
Are formed in a flat prismatic shape composed of narrow side surfaces 23 extending between the peripheral edges of the rectangular shape. The magnetic disk 3 (recording medium)
The center portion is supported by the center core 31. The center core 31 is formed by pressing a ferromagnetic plate member into a disk shape by press working or the like. The center core 31 is formed in a circular opening 2a (see FIG. 2) opened in the bottom surface 22 of the cassette shell 2. It is arranged facing. When loaded into the magnetic recording / reproducing apparatus, the center table 31 has the turntable 12 as shown in FIG.
Are connected and driven at high speed. The turntable
12 is a positioning pin with a tapered tip at the center of rotation.
13 is provided upright, and a chuck magnet 14 is annularly disposed on the outer peripheral side. The shape of the center core 31 is such that a center hole 31a in which a center positioning pin 13 of the turntable 12 is engaged is provided in a center portion, and a stepped shape is provided in an outer peripheral portion from an opening position of the center hole 31a. An annular and convex suction portion 31b having a different height is provided. The attracting portion 31b is attracted by surface contact to the connecting magnet 14 arranged annularly on the outer peripheral side of the turntable 12. On one of the four side surfaces 23 of the cassette shell 2, there is provided a magnetic head insertion opening 6 for bringing a magnetic recording / reproducing head into or out of contact with both sides of the magnetic disk 3 from outside. Have 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 an upper sleeve 81, a shutter 82, and a lower sleeve 83 extending along the bottom surface 22 are each formed of a metal plate-like member connected in a U-shaped cross section, and move along the respective surfaces. The shutter section 82 is provided with a shutter opening 82a for closing the magnetic head insertion slot 6 during storage and opening the magnetic head insertion slot 6 during operation. On the other hand, the cassette shell 2 has an upper sleeve portion 81 and a shutter portion 8 of the shutter member 8 at 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 using a torsion spring (not shown). The shutter closing spring is inserted into the inside of the cassette shell 2 through a spring insertion opening 4a formed at one end of the side surface 4 of the cassette shell 2. 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 a sliding groove 4b provided on the side surface 4 of the cassette shell 2. There are two guide claws 83a on the lower sleeve 83 of the shutter member 8.
Are engaged with guide groove portions 22a formed on the bottom surface 22 of the cassette shell 2 along the sliding direction of the shutter member 8 to prevent the shutter member 8 from coming off. In the above embodiment, when the magnetic disk cartridge 1 is used, similarly to the conventional magnetic disk cartridge, the magnetic disk cartridge 1 in the state shown in FIG. It is used by loading it into a recording / reproducing device (hereinafter referred to as device). At that time, the shutter member 8 is moved to the open position shown in FIG. 1 by an operation member provided on the apparatus side according to the loading operation. When the magnetic disk cartridge 1 is removed from the apparatus, the shutter member 8 is closed to the position shown in FIG. 2 in accordance with an ejection operation such as pressing an operation button on the apparatus side. There are various types of mechanisms on the apparatus side for opening and closing the shutter member 8, and it is considered that the realization is as easy as in the conventional apparatus. I do. In accordance with the loading into the above-described apparatus, the turntable 12 is moved to the center core 31 exposed on the bottom surface 22 of the cassette shell 2 of the magnetic disk cartridge 1.
Move relatively closer together. First, the tip of the positioning pin 13 of the turntable 12 is engaged with the center hole 31a of the center core 31, so that the center position of the center core 31, that is, the center position of the magnetic disk 3, is defined and the turntable 12 is positioned.
The attracting surface of the connecting magnet 14 on the outer periphery of the magnetic disk 3 is strongly attracted to the surface of the attracting portion 31b of the center core 31 in an annular surface contact state, 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 THE DRAWINGS FIG. 1 is a top perspective view showing a state where a shutter member of a magnetic disk cartridge according to the present invention is open. 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 a main part showing a rotation holding state of a magnetic disk. [Description of References] 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 Suction section 81 Upper sleeve section 82 Shutter section 82a Shutter opening section 83 Lower sleeve section

Continuation of the front page (56) References JP-A-58-128065 (JP, A) JP-A-61-7780 (JP, U) JP-A-59-1130 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G11B 23/03 603

Claims (1)

(1) A magnetic disk having a center portion supported by a disk-shaped center core made of a ferromagnetic plate-like member is rotatably built in a cassette shell, and In a magnetic disk cartridge in which a core faces an opening portion opened on a bottom surface of a cassette shell and is attracted to a connecting magnet provided on a turntable and is driven to rotate, the cassette shell has an upper surface slightly larger than a magnetic disk and an upper surface thereof. And a bottom surface parallel to the top surface and having a narrow width extending substantially between the top surface and the periphery of the bottom surface. A magnetic head insertion port for externally contacting or approaching both sides of the center core is provided, and a center positioning pin of a turntable is provided at a center portion of the center core. With only the center hole is provided to be engaged, the centering pin of the central hole in the outer peripheral portion
An annular suction portion having a height different from the opening position on the insertion side in a stepped manner is provided, and the suction portion is attracted by surface contact with a connecting magnet arranged annularly on the outer peripheral side of the turntable. A magnetic disk cartridge characterized in that: