JPS62157380A - Magnetic disk cartridge - Google Patents

Abstract

PURPOSE:To make the diameter of the central hole of a disk sheet into a small diameter and to increase an information recording part by constituting a center core of a plastic material containing a magnetic material and providing a hard coat covering on the surface connected to a driving device at the center core. CONSTITUTION:In a case 22 of a magnetic disk cartridge, an approximately pillar-shaped center core 23 is rotatably arranged, and the case 22 is constituted of an upper half 20 having a head inserting aperture 20a and a lower half 21 having a head inserting aperture 21b and a central aperture 21a. The center core 23 is composed of a cylinder part 23b formed by a plastic containing a magnetic material and a smaller diameter cylinder-shaped protrusion 23d than a sticking surface 23c and the cylinder part 23b to a disk sheet 25 on the cylinder part 23b. The sticking part of the sheet 25 is provided at the driving device side, a hard coat covering is provided, at the surface connected with a driving device, a central diameter hole 25a of the sheet 25 is made into a small diameter and the recording part of the information is increased.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention accommodates a flexible disc-shaped magnetic disk sheet formed to be small in diameter and extremely thin in a case, and rotates the magnetic disk sheet at high speed. Regarding magnetic disk cartridges used for magnetic recording and reproduction, in particular,
This invention relates to a magnetic disk cartridge in which the center core of a magnetic dicuff sheet is made of resin.

(Prior Art) Conventionally, floppy disks have been provided in which magnetic layers are formed on both sides of a disk-shaped base made of a flexible polyester sheet, etc., and magnetic recording is performed on the magnetic layers by a magnetic head while being rotated at high speed. It is widely used as a recording medium for computers due to its ease of handling and low cost. On the other hand, by taking advantage of these advantages of floppy disks and the unique advantage of magnetic recording, which is that the recording medium can be reused, which silver halide film does not have, still technology is developed, which uses a smaller version of the floppy disk as an image recording medium. A camera has also been proposed. The magnetic disks used in still cameras and the like are small-diameter, ultra-thin magnetic disk sheets rotatably housed in a small case, and are used as magnetic disk cartridges.

A conventional magnetic disk cartridge of this type has a so-called hat-shaped center core 1, as shown in FIGS.
0 is rotatably held in a case 11, and an inner peripheral edge 12b of a magnetic disk sheet 12 having a central circular hole 12a is adhered to a flange 10a of the center core 10. The end surface 10b of the center core 10 is exposed from the central opening 11a of the case 11 and serves as a magnetic chuck surface.
3a, and the engagement pin 13 of the drive shaft 13 is inserted into the engagement holes 10c and 10d of the end face 10b.
b and 13c are engaged, and the magnetic disk sheet 12
is adapted to be rotated within the case 11. Further, the inner peripheral edge 12b of the magnetic disk sheet 12 is normally attached to the flange portion 10a by an annular double-sided adhesive member 14.
It is designed to be affixed to

However, when the magnetic disk sheet 12 is attached to the flange portion 10a of the center core 10 as described above, the inner peripheral edge portion 12b of the magnetic disk sheet 12, which is the attachment surface, cannot be used as a recording surface, leading to a decrease in recording capacity. .

That is, in order to increase the recording capacity of a magnetic disk sheet whose outer diameter is specified, it is necessary to set the recording surface of the sheet as wide as possible toward the center of the sheet. For this reason, for example, the hat-shaped center core 10 is improved to have a smaller diameter, and the central circular hole 12 of the magnetic disk sheet 12 is
It is possible to reduce the diameter of a, but the diameter of the magnetic chuck part 13a and the positions of the engaging pins 13b and 13c of the floppy disk driver are determined by standards, so the above improvement is not practical. It's impossible.

Therefore, by using a substantially cylindrical member with one bottom surface of the center core exposed at the frontage of the center of the case, the bottom surface is used as a magnetic chuck surface, and the center core is provided with a magnetic chuck surface facing away from the magnetic chuck surface. A magnetic disk cartridge has been proposed in which a disk adhesion surface with a size smaller than the outer diameter of the chuck surface is provided, and a magnetic disk sheet is adhered to this disk adhesion surface (Japanese Patent Application No. 59-26681).
No. 7).

Furthermore, although it is preferable for such a center core to be made of plastic for manufacturing purposes, since a metal part for the magnetic chuck is not required, magnetic disk cartridges with a center core made of resin with metal insert molded on the magnetic chuck surface are also available. Conceivable.

However, in reality, this insert molding type disk cartridge is not preferable because it reduces productivity and increases loss.

(Object of the Invention) In view of the above-mentioned problems, it is an object of the present invention to provide a magnetic disk cartridge that does not increase the recording amount and cost.

(Structure of the Invention) A magnetic disk cartridge according to the present invention has a center core fixed to the center of a disc-shaped magnetic recording medium.
It is made of a plastic material containing magnetic material that can be magnetically chucked with the drive device when the disk cartridge is loaded. Furthermore, this plastic material has a rough surface because it contains a large amount of magnetic material, and if this plastic surface were to be loaded directly into the drive device, the drive device would be damaged as it was removed. It is easy to attach, but the plastic surface that comes in contact with the drive device also wears out, making it significantly less durable. For this reason, a surface layer is required to protect this plastic surface at the portion that comes into contact with the drive 5A. However, if a surface layer is applied to this plastic surface by two-color molding or the like, the thickness of the surface layer increases and the magnetic chucking properties of the plastic portion deteriorate. For this reason, it is necessary to provide a thin coating that can protect the plastic surface.

Therefore, in the present invention, a hard copy coating is provided on the outer surface of the center core in a portion that comes into contact with the drive device. This solves the above-mentioned problems caused by the rough surface of the plastic material. Note that this hard copy coating is provided not only on the above-mentioned portions but also on other portions as necessary.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

1 and 2 show a magnetic disk cartridge according to a first embodiment of the present invention.

A substantially cylindrical center core 23 is rotatably disposed within a case 22 consisting of an upper half 20 and a lower convex portion 721. This center core 23 is arranged so that one bottom surface thereof is exposed to the central opening 21a of the lower half 21. Note that the case 22 has a head insertion opening 20.
21b, a slidable shutter 24, a liner (not shown) in contact with a magnetic disk sheet 25, which will be described later, and the like, and is formed in the same manner as the case of a conventional magnetic disk cartridge.

The center core 23 is made of a plastic material containing a magnetic material. Is magnetic material a coercive material? 30e or lessB
It is preferable to use 5 x 13 glass to 87 glass.

The cylindrical portion 23b is made of plastic containing this magnetic material, and an annular surface is formed on the circumference of the upper part of the cylindrical portion 23b, and this surface is used as an adhesion surface 23c to the disk sheet 25. A cylindrical protrusion 23d having a diameter smaller than that of the cylindrical portion 23b is formed on the upper surface of the adhesion surface 23c so as to have the same center as the cylindrical portion 23b.

The disc-shaped disc sheet 25 has the above-mentioned cylindrical projection 23d.
It has a central circular hole 25a with a slightly larger diameter. That is, in the conventional one, the central circular hole 12 is larger than the outer circumference of 23b.
The central circular hole 25a has a smaller diameter than that shown in FIG. 3 12a. When fixing this magnetic disk sheet 25 to the center core 23, the central circular hole 25a
By fitting into the protrusion 23d and pressing it toward the center core 23, the peripheral edge 25b of the central circular hole 25a is adhered to the adhesive surface 23c and fixed to the center core 23.

A hole 23a into which the spindle 13b of the drive device 13 is inserted is provided in the center of the cylindrical portion 23b.

A hard coat film is formed on the inner wall of the hole 23a to protect the surface of the contact portion with the spindle. In addition, as shown in FIG. 2, the opening 21a of the lower half case 21
The bottom surface of the cylindrical portion 23b, which is exposed to the outside and serves as a magnetic chuck surface, can also be hard coated. For this hard coat film, a hard coat based on an acrylic hard coat agent, a silica sol hard coat agent, a silicone hard coat agent, etc. can be used.

The magnetic disk cartridge with the above configuration records and plays! When the plastic cylindrical portion 23b is attached to the floppy disk drive, the magnetic material is magnetically attracted to the magnetic chuck portion 13a of the rotary drive shaft 13 of the floppy disk driver, so that the plastic cylindrical portion 23b is attracted. Therefore, when the drive shaft 13 is rotated, the center core 23 is rotated, and the magnetic disk sheet 25 fixed to the center core 23 is rotated within the case 22. Further, as is well known, a magnetic head (not shown) of a recording/reproducing device comes into contact with the rotating magnetic disk sheet 25 through the head insertion openings 20a and 21b, and the magnetic head records information on the magnetic disk sheet 25. was done,
Alternatively, recorded information is reproduced from the magnetic disk sheet 25. Therefore, the recording surface of the magnetic disk sheet 25 is
The innermost circumferential portion must be set at least slightly outside of the adhesive portion.

Here, in the magnetic disk cartridge of this embodiment, the center hole of the disk sheet 25 is smaller than that of the conventional magnetic disk cartridge as described above, and the radius of the bonded part with the center core 23 is also smaller. By comparison, the distance between the innermost circumferential portion of the recording surface and the attachment portion becomes larger.

(Effects of the Invention) In the magnetic disk cartridge according to the present invention, the center core is formed of plastic containing a magnetic material, the adhesive portion with the disk sheet is provided on the drive device side, and a hard coat coating is provided on the surface in contact with the drive device. Due to the improved installation, the central circular hole of the disc seat has a smaller diameter than before.
Since the area of the adhesive portion is also reduced, the area of the information recording portion of the disc sheet increases, and the amount of information recorded increases.

In addition, due to the formation of the hard coat film, the durability of the center core is maintained, and even when the center core is rotated when the drive device is loaded, the magnetic attraction of the plastic material does not deteriorate, and the drive device does not close and the magnetic attraction of the plastic material does not decrease. Cost reduction becomes possible.

[Brief explanation of drawings]

1 and 2 are an exploded perspective view and a side sectional view showing a magnetic disk cartridge according to a first embodiment of the present invention, and FIGS. 3 J5 and 4 are exploded perspective views showing an example of a conventional magnetic disk cartridge. and a side sectional view. 22...Case 23...Center core 2
3a...Spindle insertion hole 23b...Cylindrical part 23c...Disk attachment surface 25...Pa magnetic disk sheet (Fig. 3, Fig. 4, procedural amendment writing type) To the Commissioner of the Japan Patent Office, April 1986 3rd 1, Indication of the case Special application No. 60-299276, Ku 9 2, Name of the invention Magnetic disk cartridge 3, Person making the amendment Relationship to the case Patent applicant Location 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name Title
Fuji Photo Film Co., Ltd. 4, Agent 5-2-1 Roppongi, Minato-ku, Tokyo March 5, 1986 (Date of dispatch: March 25, 1986) 6. Number of inventions increased by amendment None 7 ,
Target of correction: Drawing 8, details of correction: Correct hand-drawn drawings into inked drawings.

Claims (1)

[Claims] A disk cartridge that incorporates a disk-shaped magnetic recording medium, a drive device fixed to the center of the medium, and a center core for magnetic chucking, wherein the center core is made of a plastic material containing a magnetic material, and the center core is made of a plastic material containing a magnetic material. A magnetic disk cartridge characterized in that a hard coat film is provided on at least the surface of the center core that comes into contact with a drive device.