JP2002025214A - Magnetic disk cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart a self-centering function to a center core of a magnetic disk cartridge constituted by fixing the center core having a spindle hole to be inserted with a spindle of a drive motor of a drive assembly at its center to the central position of a magnetic disk medium. SOLUTION: A notched part 68 is disposed at a portion on the side outer than the spindle hole 61 of the center core 11 having the spindle hole 1 of a circular shape and the position of the centroid G of the center core 11 is deviated in a diametral direction from the position of the center O1 of the spindle hole 61 so that the specific position S of the inner peripheral surface of the spindle hole 61 abuts the outer peripheral surface of the spindle 72 at all times in rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-small magnetic disk cartridge having a disk-shaped magnetic disk medium accommodated in a flat cartridge case and having a large recording capacity, and more particularly to a center core having an automatic alignment function. The present invention relates to a magnetic disk cartridge.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk medium (a so-called floppy disk) in which a magnetic layer is provided on both sides of a disk-shaped base made of a flexible polyester sheet or the like and magnetically recorded on the magnetic layer by a magnetic head while being driven to rotate. (Registered trademark) disk) is provided in a flat case, and is mainly used as a recording medium for a computer because of its advantages such as easy handling and low cost.

In such a magnetic disk cartridge, a center core having a spindle hole into which a spindle of a drive motor of a drive device is inserted is fixed to a center portion of the magnetic disk medium, and a bottom surface of the center core faces outside. A hole is formed in the lower surface of the case to allow chucking of the spindle with respect to the center core.

By the way, the miniaturization of the computer using the above-mentioned magnetic disk cartridge has progressed, and the notebook type personal computer has become widespread. An external system without a built-in disk drive device has been used. The adoption of this external method is excellent in terms of portability of small personal computers.However, for example, there is a problem that a large amount of data cannot be recorded and reproduced because magnetic disk cartridges cannot be used at the carrying destination of small personal computers. This causes a problem that data cannot be recorded on a plurality of magnetic disk cartridges.

[0005] From these points, some small personal computers have a PC card slot (PCMC IA specification compliant) in which a PC card is mounted for external interface and additional memory, and this PC card slot is used. It has been proposed to configure an external storage device using a magnetic disk cartridge.

A PC that can be inserted into the PC card slot
The card is Type II and has a thickness of 5.0 mm, and the magnetic disk cartridge and the disk drive device are to be included in this thickness. Therefore, the magnetic disk cartridge has an ultra-thin thickness of about 2 mm. Must be configured.

[0007]

In such an ultra-small magnetic disk cartridge as well, a large recording capacity is required as a recording medium. The width of one recording track on the disk medium must be extremely narrow, 3 μm to 5 μm.

On the other hand, it is necessary to provide a clearance of at least about 10 μm between the spindle hole of the center core, into which the spindle of the drive motor of the drive device is inserted by magnetic attraction, and the spindle for attachment and detachment. When the width of one recording track on the magnetic disk medium is, for example, 5 μm, the clearance becomes the width of two recording tracks, and the rotation center of the magnetic disk medium fluctuates in an arbitrary direction by the clearance. become. In order for the magnetic head to trace such a track deviation, a servo signal is generally written at the head of the data area in advance. However,
In order to improve the followability of the signal track, it is necessary to minimize the physical deviation.

Conventionally, in order to prevent fluctuations in the center of rotation of a magnetic disk medium due to a clearance existing between a spindle of a drive motor and a spindle hole of a center core, for example, 3.5 inches (8 inches) widely used. .9
cm), the spindle axis is deflected to two ridges of a substantially square spindle hole of the center core (hub). And in this case,
A biasing force is obtained by inserting a drive pin provided in a drive motor of the drive device into a drive hole formed beside the spindle hole of the center core and applying a bias in a radial direction by a spring pressure.

However, in a small drive device of the PCMC IA specification, it is difficult to provide a drive pin or the like in the motor because it is necessary to reduce the size of the motor as much as possible, and it is also necessary to provide a drive hole in a small center core. Have difficulty.

In view of such circumstances, an object of the present invention is to provide a large-capacity ultra-small magnetic disk cartridge having a center core that overcomes the above-mentioned problems.

[0012]

According to the present invention, a magnetic disk medium is rotatably housed in a flat cartridge case, and a center core having a center of a spindle hole into which a spindle of a drive device is inserted is provided. The center of gravity of the center core is radially deviated from the center position of the spindle hole to a part outside the spindle hole of the center core having the circular spindle hole. A notch portion is provided.

The notch is preferably provided, for example, on the outer peripheral portion of the attaching portion of the magnetic disk medium, but may be another portion. However, from the viewpoint of the stability of chucking with respect to the spindle, it is desirable that the portion be as far away from the chucking portion as possible.

[0014]

According to the magnetic disk cartridge of the present invention, the notch is provided in a part of the center core, so that the center of gravity of the center core is deviated in the radial direction from the center position of the spindle hole, so that the rotation is prevented. The stable point of the dynamic balance at the time deviates from the center position of the spindle hole. Therefore, when the center core rotates in a state where the center core is fitted to the spindle of the drive motor of the drive device by magnetic attraction, a force acts on the center core to pull the center core toward the side opposite to the notch side with respect to the center of the spindle hole. Since the specific position on the side of the notch on the inner peripheral surface of the spindle hole always contacts the outer peripheral surface of the spindle, an automatic centering effect can be obtained.

In this case, the magnetic disk medium also performs a slight eccentric motion together with the center core. However, there is no problem because the eccentric motion is the same when recording and reproducing information. It is possible to do.

Since this ultra-small (outer diameter of about 12 mm) center core is provided with a circular spindle hole, all parts can be machined concentrically when manufacturing it, and then cut to the outer periphery. Since it is sufficient to form the notch, it is possible to improve the manufacturing accuracy even in an ultra-small size, and to simplify the mold structure, so that there is also an effect that the cost can be reduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a perspective view of a magnetic disk cartridge according to an embodiment of the present invention, showing a state in which a window for inserting a magnetic head is closed by a shutter member, as viewed from above. FIG. 2 is a perspective view of a state in which the magnetic head insertion window is opened as viewed from the lower surface side. FIG. 3 is an exploded perspective view of the magnetic disk cartridge. In addition, in order to clarify the structure, the thickness and the like of each part in the drawings are shown in proportions different from actual dimensions.

The magnetic disk cartridge 1 has a disk-shaped magnetic disk medium 10 (see FIG. 3) rotatably housed in a flat cartridge case C.
The cartridge case C includes a base plate 2 serving as a central member.
And a substantially planar upper cover case 3 and a lower cover case 4 attached to the top and bottom of the base plate 2. The magnetic disk medium 10 has a disk-shaped base made of a flexible polyester sheet or the like provided with magnetic layers on both sides, and has a metal center core 11 fixedly integrated at the center.

The base plate 2 of the cartridge case C
A hole 27 for accommodating the annular portion 66 (see FIG. 4) of the center core 11 is provided in the center of the center core 11. Further, the lower cover case 4 has a size substantially equal to the size of the hole 27 at a position overlapping the hole 27. The magnetic disk medium 10 is housed in the cartridge case C such that the bottom surface of the annular portion 66 of the center core 11 faces outside from the hole 7.

At the front end of the cartridge case C with respect to the direction of insertion D (arrow in FIG. 1) with respect to the drive device, there is formed a window 8 accessible by a recording / reproducing magnetic head. The window 8 is vertically penetrated and opened from the front end faces of the base plate 2 and the upper and lower cover cases 3 and 4 toward the center thereof in a rectangular shape (see FIG. 2). A shutter member 5 for opening and closing the portion 8 is built inside the upper and lower cover cases 3 and 4 so as to be slidable in the left-right direction.

With such a structure of the window 8, the recording / reproducing magnetic head can be inserted into the window 8 from the front end side of the cartridge case C without opening and closing greatly up and down.
In addition, the adoption of the built-in shutter member 5 prevents the shutter member 5 from coming off due to insufficient strength due to miniaturization, becomes strong against dropping, etc., and has good assemblability.

Next, the structure of each component will be specifically described with reference to FIG.

First, the base plate 2 is formed of a synthetic resin such as acrylonitrile-butadiene-styrene copolymer (ABS resin) or POM resin, and has a substantially rectangular flat plate shape. A circular recess 21 for accommodating the disk medium 10 is formed, and the hole 27 is formed in the center of the thin bottom plate of the recess 21.
Is open. Further, the front end portion of the bottom plate of the concave portion 21 is cut into a substantially rectangular shape to form a space 22 into which a below-described lower plate portion 52 of the shutter member 5 is movably inserted.
The central portion of the front end portion of the base plate 2 is removed in the front-rear direction, and the window 8 is opened vertically. Then, one side of the window 8 of the base plate 2 (the right side in FIG. 3)
The front surface of the front wall is retracted from the front surface of the front wall on the other side (the left side in FIG. 3) to form a spring storage portion 23. In this portion,
A shutter spring 6 described later is arranged.

Further, the corner portions 25 at the four corners of the base plate 2 are formed so as to protrude in the vertical direction and have a large thickness and project outward. The four corner portions of the upper and lower cover cases 3 and 4 correspond to the corner portions. When the upper and lower cover cases 3 and 4 are fitted to the base plate 2, the corner portions 25 of the base plate 2 are exposed to the outside. Each corner portion 25 is provided in a shape in which the surface protrudes flush or outward with the surface of the upper and lower cover cases 3 and 4.

By exposing the corner portion 25 of the base plate 2 to the outside as described above, when a shock or the like at the time of a drop acts, the corner portion 25 can absorb the shock, and can be inserted into the drive device and inserted. At the time of unloading operation, it is prevented from getting stuck and stable operation is ensured. In each corner 25, a hole 26 penetrating in the vertical direction (a hole having an intermediate depth without penetrating) may be used.
Is provided so as to obtain a larger buffering action at the time of a drop impact. The base plate 2 has a strength that allows a deformation that does not hinder the recording and reproduction of the magnetic disk medium 10. However, from the viewpoint of shock absorption, the base plate 2 is preferably made of an elastic plastic. In addition, a material containing a lubricant is preferable in terms of sliding with respect to the shutter member 5, and a material containing a filler material is used in order to improve dimensional accuracy and improve assemblability with the cover cases 3 and 4. Is good.

A notch-shaped concave portion 15 is formed on the side surface of the corner portion 25 on both sides of the front portion of the base plate 2 as shown in FIG. 1, and this concave portion 15 is used for positioning when mounted on the drive device. Alternatively, it is provided to prevent erroneous insertion in the front-back direction or the front-back direction. The recess 15 may be provided only on one side surface or on the side surface of the rear corner portion 25. In the case of the present embodiment, the corner of one of the front corners 25 is notched diagonally to form the erroneous insertion prevention part 16.

Further, on the side surface of the cartridge case C, a cover case 3 near the rear corner 25, for example, as shown in FIG.
Although the discrimination unit 17 for disc type (for example, the type of recording capacity) is provided on the side wall of No. 4, a write protector unit may be provided here. Furthermore, the identification section 17 may be provided with an identification piece that enables the detection function to be turned on / off so as to be able to be inserted or inserted / extracted. By forming the concave portion 15 and the identification portion 17 on the side surface, a detection mechanism or the like on the drive device side that does not have a vertical installation space can be disposed laterally.

The upper and lower cover cases 3 and 4 are formed of a high-strength material such as a pressed stainless steel plate. The upper cover case 3 and the lower cover case 4 are substantially symmetrical, and the four corners are rectangular. It is removed, a flat rectangular window 8 is opened in the center of the front part, and the front, rear, left and right edges are bent at right angles, and the front walls 31, 41, both side walls 32, 42, respectively.
The rear wall portions 33 and 43 are configured. The front wall portion 3 on one side (the left side in FIGS. 1 and 3 and the right side in FIG. 2) with respect to the window portion 8.
The slits 18 (see FIG. 1) are formed between the upper and lower front wall portions 31 and 41 when the upper and lower cover cases 3 and 4 are attached to the base plate 2. It has become. The shutter opening / closing member on the drive device side is inserted into the slit 18 and moves along the slit 18 to open the shutter member 5. The front walls 31 and 4 on the opposite side of the window 8 (the right side in FIGS. 1 and 3 and the left side in FIG. 2).
1, that is, a notch is formed at the end side of the portion located in front of the spring storage portion 23, and the upper and lower cover cases 3,
A rectangular spring insertion opening 19 (see FIGS. 1 and 2) is formed in a state where the front wall portions 31 and 41 of the shutter 4 are fitted together, and is used for mounting the shutter spring 6.

The shutter member 5 is inserted between the base plate 2 and the upper and lower cover cases 3 and 4 and into a sliding space 22 opened in the base plate 2 on the lower surface side, and is slidably mounted in the left and right opening and closing directions. You. The shutter member 5 is made of metal, for example, formed in a substantially U-shaped cross section from a stainless steel plate or an aluminum plate. The upper plate portion 51 and the lower plate portion 52 are connected by a connecting portion 53 at the front end. The height of 53 is substantially equal to the thickness of the front part of the base plate 2. Then, a shutter window 54 is formed by being cut out in a substantially rectangular shape from the connecting portion 53 to the upper surface plate portion 51 and the lower surface plate portion 52. The shutter window 54 has a size substantially corresponding to the window 8 of the cartridge case C, and is communicated with the shutter window 54 during the opening operation. The shutter window 54 is provided at a position deviated from the center of the shutter member 5, and together with the connecting portion 53, the cartridge case C
A closing area for closing the window 8 is formed adjacent to the shutter window 54.

A spring receiving projection 55 bent from the connecting portion 53 of the shutter member 5 is provided on the inner surface of the front end of the shutter window 54 on the closed area side, and the shutter spring 6 formed of a coil spring in the opening and closing direction is provided on the back thereof. When contracted, the shutter member 5 is urged in the closing direction. Although not shown, at least one of the upper surface plate portion 51 and the lower surface plate portion 52 is cut and raised, and is engaged with a guide groove extending in the left and right direction on the base plate 2 so as to be assembled. It is useful for preventing the coming off. Reinforcing ribs 56 are formed on the upper plate portion 51 and the lower plate portion 52 of the shutter member 5 to prevent deformation during the opening operation. The reinforcing rib 56 is formed in a protruding shape protruding outward to suppress the generation of abrasion powder and the like due to the sliding of the tips of the upper and lower plate portions 51 and 52 contacting the upper and lower cover cases 3 and 4. It also has the effect of reducing the frictional resistance of the device and ensuring the stability of the opening and closing operation.

Above and below the magnetic disk medium 10, a sliding sheet 12 made of a plastic sheet or the like having a PET sheet surface subjected to sliding processing (Teflon (registered trademark) processing) is interposed. The sliding sheet 12 has a portion corresponding to the window portion 8 removed in the radial direction to form a substantially C-shape, and an opening 12 a is formed in a portion opposite to the window portion 8, and a cleaning member 13 is provided in this portion. The cleaning member 1 is fixed to the inner surface of the upper cover case 3 and the bottom surface of the base plate 2 from the magnetic disk medium 10 side.
At the same time, the sliding sheet 12 is fixed by the fixing of the sliding sheet 3.
The cleaning member 13 is brushed on the side facing the magnetic disk medium 10 and comes into contact with the surface of the magnetic disk medium 10 to remove dust on the surface. An adhesive is applied to the opposite surface of the cleaning member 13.

To assemble the magnetic disk cartridge 1, the sliding sheet 12 is fixed to the circular concave portion 21 of the base plate 2 and the lower surface of the upper cover case 3 in advance by fixing the cleaning member 13 to the circular concave portion 21 of the base plate 2. After the magnetic disk medium 10 is set in the shutter member 5, the shutter member 5 is mounted from the front. Subsequently, the upper cover case 3 is fitted to the base plate 2 from above and the lower cover case 4 is fitted and held from below to form an integral unit. 4 is spot-welded. As a result, the upper surface of the circular recess 21 of the base plate 2 is covered with the upper cover case 3, and the flat space defined by the bottom surface of the upper cover case 3 and the upper surface of the circular recess 21 becomes a storage space for the magnetic disk medium 10. The magnetic disk medium 10 is rotatably stored. Thereafter, the coil-shaped shutter spring 6 is bent from the spring insertion port 19 in the front wall portion of the upper and lower cover cases 3 and 4 while the inner spring housing 2 is being bent.
3 and the front end thereof is brought into contact with the spring receiving projection 55 of the shutter member 5, and the rear end is pressed into the storage portion 23 while being contracted, thereby completing the assembly. In addition, the spring insertion port 1
9, the shutter spring 6 assembled
Is locked out.

When the magnetic disk cartridge 1 is loaded in the drive device, the pawl of the opening / closing mechanism is inserted into the slit 18 at the front end, engages with the end of the shutter member 5, and moves it in the opening direction. Manipulate. Along with this, the window 8 of the base plate 2 is opened to be in the state shown in FIG.

As shown in FIGS. 4 and 5, the center core 11 has a disc-shaped portion 62 having a circular spindle hole 61 extending between its upper and lower surfaces 62a and 62b.
And an annular portion 66 protruding downward coaxially with the spindle hole 61 around the lower surface 62b of the disc-shaped portion 62.
Around the upper surface 62a of the disc-shaped portion 62,
And a flange 67 provided on the upper surface with a magnetic disk medium attaching surface 67a formed in an annular shape one step below 2a. In the present embodiment, the outer diameter of the flange 67 is 12.6 mm, and the inner diameter of the spindle hole 61 is 2.8 mm. 4 and 5, a notch 6 is provided at the left end in FIGS.
8 are formed. Therefore, the position of the center of gravity G of the center core 11 in the plan view of FIG.
It is offset to the right side of FIG. 5 than the center O ₁ of the. In addition,
The notch, as shown at 68 ',
It may be formed on the outer periphery of the annular portion 66.

On the other hand, the spindle 70 of the drive motor of the drive device has a columnar portion 61 having a flat upper surface 71a which is in close contact with the lower surface 62b of the disk-shaped portion 62 of the center core 11 at the center of the flat upper surface 70a. Further, a cylindrical small diameter portion 72 inserted into the spindle hole 61 of the center core 11 is coaxially provided at the center of the cylindrical portion 61. Further, a permanent magnet 73 for magnetically attracting the lower surface 62b of the disc-shaped portion 62 of the center core 11 to the surface 71a is embedded in the flat upper surface 70a.

The inner diameter of the spindle hole 61 of the center core 11 is the same as that of the spindle 70 inserted into the spindle hole 61.
Is formed slightly larger (about 10 μm).

In the above configuration, the center core 11 is attached to the small diameter portion 72 of the spindle 70 of the drive motor of the drive device.
When There center core 11 is rotated in a state being fitted by magnetic attraction force pulling the opposite effect this with notch 68 side with respect to the center O ₁ of the spindle hole 61 in the center core 11 by the difference between the centrifugal force and, specific position S of the inner peripheral surface cutout portion 68 side of the spindle hole 61 are always in contact with the outer peripheral surface of the spindle 70, the center O ₁ of the spindle hole 61 is always a constant direction from the rotation center O ₂ of the spindle 70 As a result, the self-centering effect is obtained.

In this case, the center O _{1 of the} spindle hole 61
Rotates depicts a rotation center O ₂ circularly spindle 70, along with this, it would be a magnetic disk medium is performed slight eccentric movement, the eccentric motion of the same embodiment in the time of recording information and playback Therefore, there is no problem, and stable recording and reproduction can always be performed.

When the center core 11 is manufactured, all parts can be machined concentrically, and then the notch 68 may be formed in the outer peripheral portion. Also, the manufacturing accuracy can be improved and the mold structure can be simplified, so that there is also an effect that the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of a magnetic disk cartridge according to the present invention, showing a state where a window for inserting a magnetic head is closed by a shutter member, as viewed from above.

FIG. 2 is a perspective view of the magnetic disk cartridge shown in FIG. 1, showing a state in which a window for inserting a magnetic head is opened, as viewed from a lower surface side;

FIG. 3 is an exploded perspective view of the magnetic disk cartridge shown in FIGS. 1 and 2;

FIG. 4 is an enlarged sectional view of a main part of the magnetic disk cartridge shown together with the spindle.

FIG. 5 is an enlarged plan view showing a state in which the center core is rotationally driven by a spindle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic disk cartridge C cartridge case 2 Base plate 3 Upper cover case 4 Lower cover case 5 Shutter member 6 Shutter spring 8 Magnetic head insertion window 10 Magnetic disk media 11 Center core 12 Sliding sheet 13 Cleaning member 19 Spring insertion opening 21 Circular recess 23 Spring storage part 25 Corner part 61 Spindle hole of center core 61a Cylindrical wall part of spindle hole 62 Disc part of center core 67 Flange part of center core 68 Notch part 70 Spindle

Claims (1)

[Claims] 1. A magnetic disk medium is rotatably accommodated in a flat cartridge case, and a center core having a spindle hole into which a spindle of a drive motor of a drive device is inserted is fixed at a center position of the magnetic disk medium. A notch portion radially offset from a center position of the spindle hole in a part of the center core having a circular spindle hole outside a spindle hole of the center disk. A magnetic disk cartridge characterized by comprising: