JPH0586170U - Magnetic disk cartridge - Google Patents

Abstract

(57) [Abstract] [Purpose] A magnetic disk cartridge with a lifter that retains spring force even at high temperature storage, does not generate liner wear, collects dust on the surface of the magnetic disk, and can prevent dropout. To provide. A magnetic disk cartridge comprising a pair of upper and lower shells in which a magnetic disk sheet is rotatably accommodated and a liner for cleaning the magnetic layer surface of the magnetic disk is provided on the inner wall surface of the magnetic disk sheet. A lifter that presses the liner against the surface of the magnetic layer of the magnetic disk is installed between the two, and the lifter has a glass transition temperature of 90 ° C. or higher and a product of the Young's modulus E and the cube of the thickness t is 6
A magnetic disk cartridge characterized by being a sheet-shaped resin in the range of 00 g · mm to 3000 g · mm.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic disk for data recording used as a magnetic recording medium for high density recording, and more particularly to a lifter for a magnetic disk cartridge.

[0002]

[Prior Art]

 In recent years, magnetic disk cartridges have been used as magnetic recording media for computers or video. For example, with the spread of mini-computers as OA equipment and personal computers, magnetic recording disks as external storage media have spread remarkably, the frequency of use of magnetic recording disks has increased, and they have been used and stored under a wide range of environmental conditions regarding temperature and humidity. Also, it has come to be used in places where there is much dust in the operating environment.

In particular, there is a strong demand for an improvement in recording density in order to achieve a large recording capacity and a small recording size, and the shortest recording wavelength is about 1 μm or less. Further, a large narrow track width is required for high density recording. Specifically, a high-capacity magnetic recording disk having a capacity of 10 Mbytes or more has been created, and an attempt has been made to reduce the track width of 120 μm for a conventional 1 M or 2 Mbyte to about 40 μm, which is about 1/3.

Therefore, even in a magnetic disk cartridge having such a magnetic disk, further improvement in cleaning characteristics is desired in order to meet such a demand. In a magnetic disk cartridge, a circular opening is generally formed in at least one shell of a cartridge main body composed of upper and lower shells, and a center core portion of a magnetic disk accommodated in the cartridge main body is formed in the opening. Also, for signal recording, head insertion openings are provided on both upper and lower shells, and the head insertion openings are normally shielded by a shutter made of metal such as stainless steel or synthetic resin.

A cleaning liner is provided on the inner surface of the shell, and at least one of the inner surfaces of the shell holds one end between the liner and the inner surface of the shell and the non-holding portion pushes up the liner. The lifter is installed so as to contact the magnetic sheet. Usually the lifter is made of polyester sheet. As described above, the function of the lifter provided in the cartridge body is to constantly push up the liner while the magnetic disk is rotating to collect dust on the surface of the magnetic disk. The lifter must always have a force (spring force) that pushes up the liner, and if this spring force is lost, dust collection performance deteriorates and dropouts easily occur.

Conventionally, a polyethylene terephthalate film of 125 μm has been used for this lifter. However, in recent years, magnetic disk cartridges have been widely used, and storage places have been exposed to high temperatures such as in automobiles. The polyethylene terephthalate film that has been conventionally used has little deterioration in spring force if the ambient temperature is about 40 ° C. However, if it is stored at a high temperature of 80 ° C., it deforms and loses the spring force.

Further, it has been attempted to use a thin plate made of stainless steel or various resins as a material which is not thermally deformed at a high temperature. In the case of stainless steel, the cost will be significantly increased, the machining process will be complicated, and the spring force will be too strong, so the liner will come into close contact with the magnetic disk, or the lifter will hit the liner unevenly, so it will run for a long time. In such a case, there is a problem that the so-called disc surface may have fine scratches due to a liner called liner wear. Also, in the case of resin, a material satisfying both the above-mentioned improvement of cleaning characteristics and prevention of liner wear has not been obtained.

Therefore, there is a demand for a lifter that retains the spring force without being thermally deformed even when stored at a high temperature of 80 ° C., and only retains the spring force required to collect dust on the surface of the magnetic disk.

[0009]

[Problems to be solved by the device]

 The present invention has been made in view of such a problem.The lifter has a lifter that retains spring force even at high temperature storage, does not generate liner wear, collects dust on the magnetic disk surface, and prevents dropout. The purpose is to provide a magnetic disk cartridge that has

[0010]

[Means for Solving the Problems]

 The present invention relates to a magnetic disk cartridge comprising a pair of upper and lower shells in which a magnetic disk sheet is rotatably housed and a liner for cleaning the magnetic layer surface of the magnetic disk is provided on the inner wall surface of the magnetic disk cartridge. A lifter that presses the liner against the magnetic layer surface of the magnetic disk is installed between the inner wall surfaces. The lifter has a glass transition temperature of 90 ° C or higher, and the product of Young's modulus E and the cube of thickness t is 600g. A magnetic disk cartridge characterized by being a sheet-shaped resin in the range of mm to 3000 g · mm.

The disk cartridge of the present invention is preferably a magnetic disk used in a high recording density digital recording system in which a magnetic disk sheet has a track width of 50 μm or less. Further, the magnetic disk is preferably one having a high capacity of 4 Mbytes or more, more preferably 10 Mbytes or more.

The present invention is a lifter material that stably supplies an appropriate force to a liner that does not damage the surface of a magnetic disk and keeps the surface clean even in a wide range of environments, especially in high temperature environments. The present inventors have found a criterion for selecting a resin as a resin, and the selection criterion is that the glass transition temperature is 90 ° C. or higher, more preferably 100 ° C. or higher, and particularly preferably 110 ° C. or higher. A sheet-like resin having a product Et ³ of the third power of 600 g · mm to 3000 g · mm, more preferably 650 to 2650 g · mm, and particularly preferably 720 to 2200 g · mm.

If Et ³ is too small or too large, the contact of the liner with the magnetic layer surface is too weak or too strong, which is not preferable. That is, if the hit is too weak, the cleaning effect is not sufficient and dropout increases especially in a high-capacity floppy disk, and if too strong, the liner and the disk surface are damaged.

If the glass transition temperature (Tg) of the lifter is less than 90 ° C., the pressure is weakened and the cleaning effect is lowered when the magnetic disk cartridge is used in an environment of particularly high temperature, which is not preferable. On the other hand, the present invention provides a lifter that does not undergo thermal deformation even when exposed to a high temperature of 80 ° C and maintains a stable spring force.

The lifter material of the present invention is not limited as long as it is a resin satisfying the above conditions, and can be appropriately selected and used from resins such as polymers having known chemical structures or compositions thereof. Preferred examples of the lifter material include polyethylene naphthalate (Tg: 113 ° C., Young's modulus: 570 to 1330 Kg / mm ² ), polyimide (Tg: 350 ° C., Young's modulus: 710 to 1360 Kg / mm ² ), polyaramid ( Tg: 280 ° C., Young's modulus: 850 to 2080 Kg / mm ² ), syndiotactic polystyrene (Tg: 100 ° C., Young's modulus: 390 to 420 Kg / mm ² ), polyether ether ketone (Tg: 143 ° C., Young's modulus: The resin sheet is uniaxially or biaxially stretched such as 1160 kg / mm ² ). If the Young's modulus E cannot be sufficiently taken because Et ³ is not stretched or is insufficiently stretched and Et ³ cannot be controlled within the range of the present invention, the object of the present invention cannot be achieved. Among the resins, polycarbonate and polysulfone are not preferable because they have a small Young's modulus.

The thickness of the lifter can be arbitrarily set so that Et ³ is in the range of the present invention, that is, in the range of 600 to 3000 g · mm. Therefore, when the value of E is small, t may be increased, and when the value of E is large, t may be decreased to obtain the above value. , 70 to 150 μm, preferably 100 to 125 μm, and the range of E is 300 to 2000 Kg / mm ² , preferably 400 to 1500 Kg / mm ² .

The known coating type magnetic recording medium in which a ferromagnetic material is held on a non-magnetic support, or a ferromagnetic metal thin film type magnetic recording medium can be applied to the structure of this magnetic disk sheet. The coating type magnetic recording medium is prepared by coating a support with a coating solution for a magnetic layer containing mainly a ferromagnetic powder and a binder, and drying the coating solution to provide at least one magnetic layer. In particular, a thin magnetic layer is preferable for a magnetic disk for high-density recording. Specifically, a non-magnetic powder is formed on a non-magnetic support and a ferromagnetic powder is formed on a non-magnetic layer mainly containing a binder. Those prepared by providing a magnetic layer whose main component is a binder. In addition to these components, the non-magnetic layer and the magnetic layer may contain known dispersants, lubricants, antistatic agents, abrasives and the like.

Examples of the non-magnetic powder used in the non-magnetic layer include inorganic powder such as titanium dioxide, carbon black and the like. Examples of the ferromagnetic powder contained in the magnetic layer include Fe or a ferromagnetic alloy powder mainly composed of Fe, and a ferromagnetic hexagonal ferrite powder. The particle size and particle shape of these powders can be appropriately selected. Yes, it is selected variously depending on the desired thickness of the magnetic layer and the like.

The coating method of the magnetic disk is not particularly limited, but a preferable method is a wet-on-wet coating method in which the magnetic layer is coated on the non-magnetic layer while it is in a wet state. The thickness of the magnetic disk is preferably 30-80 μm for the non-magnetic support, 0.5-10 μm for the non-magnetic layer, and 1 μm or less, particularly 0.5 μm or less for the magnetic layer.

Hereinafter, a specific structural example of the present invention illustrated in the drawings will be described. FIG. 1 is a schematic view of the magnetic disk cartridge of the present invention as viewed from the back, side, and front, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. The magnetic disk cartridge includes a floppy disk 10, which is a magnetic recording medium, and a protection and cleaning for the floppy disk 10 in a case which is composed of an assembly of upper and lower shells 1 and 2 made of relatively hard plastic side surfaces. For this purpose, a liner 13 made of non-woven fabric and a lifter 11 for abutting the liner 13 on the surface of the sheet with appropriate strength are incorporated. The floppy disk 10 has a center core 4 which is held by the rotation driving means of the recording / reproducing apparatus at the center thereof, and the center core 4 is exposed on the surface of the case. The center core 4 is provided with a center hole 8 and a chucking hole 7. The shell is provided with an HD hole 6 and a light protector 5.

A rectangular head window 9 is provided in the case so that the magnetic head of the recording / reproducing apparatus can slide on the surface of the sheet, and a slide for closing the head window 9 when the cartridge is not used. A possible dustproof shutter 3 is provided. The liner 13 is arranged on both upper and lower sides of the floppy disk 10 and has a shape which can be said to be a substantially donut-shaped disc shape corresponding to almost the entire area of the disk recording surface. The floppy disk 10 is sandwiched between the upper and lower liners by an appropriate spring force of the lifter 11. Here, the upper liner projects slightly at this nip to ensure contact with the floppy disk. The lifter 11 is fixed to the lower shell by an adhesive such as a pressure-sensitive adhesive, a curable adhesive, or ultrasonic welding, and is provided with a protrusion 14 as an auxiliary in order to appropriately maintain the spring force thereof. Has been.

In the present invention, the holding mechanism in the lifter cartridge is optional, and for example, it may be a single-support type in which only one end of the lifter is fixed to the shell, or a double-support type in which both ends are supported. The shape of the lifter before fixing is usually rectangular, but the shape is basically not limited.

[0023]

【Example】

 Hereinafter, specific embodiments of the present invention will be described, but the present invention is not limited thereto. The magnetic disk cartridge of the present embodiment is a 3.5-inch floppy disk in which a magnetic disk having a diameter of 86 mm attached to the center core is housed in the upper and lower shells, and has a storage capacity of 4.0 Mbytes. The track width is 120 μm. The floppy disk has a nonmagnetic support made of polyethylene terephthalate having a thickness of 75 μm, a nonmagnetic layer thickness of 2.0 μm and a magnetic layer thickness of 0.7 μm.

Further, the structure of the magnetic disk cartridge is the same as that described in FIGS. A heat-resistant ABS resin (ABS resin X27 manufactured by Toray Industries, Inc.) having a heat distortion temperature of 95 ° C. was used for the upper and lower shells, SP 9246 manufactured by Veratech Co., Ltd. was used for the liner, and a metal shutter was used for the shutter. As for the lifter, various materials as shown in Table 1 were changed to prepare samples of micro floppy disk. For comparison, polyethylene terephthalate and stainless steel thin plates, which were used conventionally, were also combined to create a sample. For each sample, a dropout evaluation test was performed on the product stored at 23 ° C. 50% RH after preparation and the product stored at 80 ° C. 30% RH for 48 hours and stored at 23 ° C. 50% RH.

[0025]

[Table 1]

Dropout evaluation conditions Measurement method: An MP-F40-W type manufactured by Sony Corporation was used as a floppy disk drive. The measurement of dropout was performed according to JIS-X6223. That is, recording is performed at the 2F frequency specified in JIS-X6223, and a data recording pit with a recording amplitude (Op) that is less than 55% of 1/2 of the average signal amplitude (pp) of the recording signal at that time is dropped. Detected as out. As a measuring instrument, a model 5135 diskette certifier manufactured by Mount Computer Inc. in the United States was used.

Dropout evaluation method: Each sample was put in and taken out of a floppy disk drive 30,000 times, and a desorption test was carried out. Then, dropout was examined. Measurement environment: 23 ° C., 50% RH Table 2 shows the evaluation test results for each sample, and the quality of the appearance deterioration due to the liner wear on the disk surface (good ◯, slightly poor Δ ◯, poor Δ, bad x).

Further, methods for measuring Young's modulus, thickness, and Tg, which are physical properties of the lifter, will be described below. The Young's modulus was measured by using a tensile tester (manufactured by Toyo Baldwin, universal tensile tester STM-T-50BP) in an atmosphere of 23 ° C. and 70% RH at a tensile rate of 10% / min. The thickness of each lifter was measured by stacking 10 lifters with a micrometer, and the thickness per sheet was measured.

Tg was measured at a frequency of 110 Hz using a dynamic viscoelasticity measuring device (Rheovibron manufactured by Toyo Baldwin). Tg is the peak temperature of the loss elastic modulus E ″.

[0030]

[Table 2]

From Table 2, the sample with inferior dropout is No. 1c, 1d, 4c, 4d, 5b, 5c and 5d. First, No. Both 1c and 1d are inferior regardless of the presence or absence of storage at 80 ° C. and 30% RH for 48 hours. This tendency is considered to be due to the low Et ³ value, which is an indicator of the lifter spring force, of 291 g · mm. The same is true for No. The same can be said for 4c, 4d and 5c. No. No. 5b is No. Compared to 5a, the effect of storage at 80 ° C. and 30% RH for 48 hours is apparent. It is considered that Tg of the polyethylene terephthalate, which is a lifter, was lower than 69 ° C and 80 ° C, and thermal deformation occurred. No. 5d has a lower lifter Tg of less than 80 ° C. and a low Et ³ and is thought to have further deteriorated dropout.

From the liner wear in Table 2, the x level is No. 3c, 3d, 6a and 6b. No. 3c and 3d have good dropout characteristics, and it is considered that dust is sufficiently collected, but the fact that liner wear is occurring means that Et ³ is higher than necessary and that the disc surface is spinning. It is probable that the liner was hit hard. The same applies to No. The results also apply to the samples 6a and 6b, and the liner strongly contacts the disk surface.

No. 2a, 2b, 3a, and 3b were slightly inferior in level, and the liner was slightly worn. It is presumed that this is due to a slightly high Et ³ . Although the example of Table 1 is given as an example of the present invention, the present invention is not limited to this example.

[0034]

[Effect of the device]

As described above, according to the magnetic disk cartridge of the present invention, when the glass transition temperature of the lifter is 90 ° C. or higher, the product Et ³ of the Young's modulus E and the cube of the thickness t is 600 g · mm to 3000 g · mm. By using a lifter in the range, dropout does not occur when using a floppy disk with a track width of 50 μm or less for high-density recording, and the liner wafer is maintained even if the environment is maintained at 80 ° C or more. It is possible to obtain a magnetic disk cartridge that does not generate

[Brief description of drawings]

FIG. 1 is a diagram illustrating an external structure of a specific example of a magnetic disk cartridge of the present invention.

FIG. 2 is a view showing a cross section taken along line II-II of FIG.

[Explanation of symbols]

 1 Upper shell 2 Lower shell 3 Shutter 4 Center core 5 Light protector 6 HD hole 7 Chucking hole 8 Center hole 9 Head window 10 Floppy disk 11 Lifter 12 Label area 13 Liner 14 Protrusion 15 Lifter holding part 16 Lifter push-up part

Claims (2)

[Scope of utility model registration request] 1. A magnetic disk cartridge comprising a pair of upper and lower shells in which a magnetic disk sheet is rotatably accommodated and a liner for cleaning the magnetic layer surface of the magnetic disk is provided on an inner wall surface of the magnetic disk sheet. A lifter that presses the liner against the surface of the magnetic layer of the magnetic disk is installed between the inner wall surfaces. The lifter has a glass transition temperature of 90 ° C. or higher, and the product of Young's modulus E and the cube of thickness t is 600 g. A magnetic disk cartridge, which is a sheet-shaped resin in the range of mm to 3000 g · mm. 2. The magnetic disk cartridge according to claim 1, wherein the magnetic disk sheet rotatably accommodated in the shell is a magnetic disk used in a high recording density digital recording system having a track width of 50 μm or less. ..