FR2635219A1 - - Google Patents

Abstract

The invention relates to flexible magnetic disks. It relates to a flexible magnetic disc having a hub 3 comprising a leaf spring 28 intended to center the disc on a drive spindle 44. According to the invention, the lower part 32 of the leaf spring 28 is folded towards the center. exterior so that the edge of the blade cannot catch on the frustoconical upper part 45 of the spindle 44. Application to flexible data recording disks.

Description

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  No. 4,630,156. The magnetic disk is schematic

  shown in Figures 10 and 11.

  Referring to Figures 10 and 11; a magnetic disk

  A flexible tick having the general reference a comprises a flexible magnetic sheet b and a central core c attached to a central portion of the magnetic sheet b. The central core has a contact hole formed in a central portion and has two positioning surfaces formed at the inner periphery of the contact hole d. The positioning surfaces e are on two equal sides among

  the three sides of an isosceles triangle or practically equi-

  lateral in plan, while a spring plate f is on the remaining side of the triangle. The spring plate f is supported at its opposite longitudinal ends in two slots g formed in the inner peripheral portion of the contact hole d of the central core c so that it can

  be deformed in the direction of its thickness, that is,

  perpendicularly to its plane, in translation with respect to the surfaces of the positioning of the contact hole

d of the central core c.

  Such a magnetic disk a is mounted, so that it can rotate, in a cassette case, no

  shown, and when this case is mounted in a

  A cassette drive shaft present in the cassette receiving portion penetrates the contact hole of the central core c of the magnetic disk 1. In this case, a cassette drive shaft of a disk drive assembly , the positioning surfaces e of the central core c and a lower end face i of the spring plate f

  are in contact with an inclined face k of an upper part

  than the frustoconical portion of the drive shaft

  and slide down this inclined face

  k, and then the spring plate f deforms elastically

  it deviates from the positioning surfaces e under the action of the inclined face k of the shaft h so that the magnetic disk a can be mounted on the shaft h. On the other hand, the positioning surfaces of the central core UT; u q aiq.zu I ap aenaT1zgdnf aTzud eu op ugual5p g. ote

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  that the magnetic disk a can be positioned, when the same disk or another disk a must be subsequently mounted on the shaft h, the probability of attachment of the spring plate by the deteriorated part of the shaft h increases significantly , so it is possible that the disc does not

  can not be loaded in position.

  The subject of the invention is a flexible magnetic disk

  which ensures a regular introduction of the training tree

  a disk drive assembly into a hole

contact of a central core.

  For this purpose, the invention relates to a magnetically

  which flexible comprises a flexible magnetic sheet having a circular outer periphery, an elongated metal spring plate having a main portion and two

  support parts at both ends of the main part

  blade, and a hub attached to the flexible magnetic sheet in the center of the sheet and having an axially formed hole, the

  hub having two locating surfaces at locations

  spaced apart from each other about a central axis of the hub hole, this hub having two seats intended for

  accommodate the support parts of the allonium metal plate

  spring plate so that the metal plate is carried by the hub in such a way that the main part of the elongated metal spring plate is opposite the two positioning surfaces, a portion contiguous to a lower end of the main body part. the spring metal plate being spaced from the central axis of the

hole by folding.

  When using this magnetic disk

  when a drive drive shaft of a drive assembly is introduced into the hole of the hub, the folded portion of the lower end of the spring plate contacts an upper face or a

  inclined face of an upper part of the drive shaft.

  disk and is deformed radially elastically

  outwardly by this face, so that the tree of

  stretching can be introduced regularly into the hole

  hub. In this case, as the contiguous part at the end

  When the lower metal spring plate is folded away from the opposite side of the central axis of the hole, the spring metal plate has no edge that could penetrate the upper part of the disk drive shaft. Thus, the problem that may arise when mounting a magnetic disk on a drive shaft, because the spring plate enters an inclined face or an upper face of the drive shaft and prevents the further mounting of the disc, is deleted. As a result, the mounting and centering of the magnetic disk

  can be achieved gradually, and the upper part

  the drive shaft is not damaged by

  the spring plate of the magnetic disk.

  Other features and advantages of the invention

  will be better understood by reading the description

  which will follow examples of embodiment, with reference to the accompanying drawings in which: Figures 1 (A) and 1 (B) are axial sections of a magnetic disk, at different stages of mounting on a spindle, in a preferred embodiment of the invention; Fig. 2 is a plan view of the magnetic disk of Fig. 1 (A); Fig. 3 is a perspective view of a portion of the magnetic disk shown in Fig. 1 (A); Figure 4 is an enlarged section along the line IV-IV of Figure 2; Figure 5 is an exploded partial perspective of the magnetic disk of Figure 1 (A);

  FIG. 6 is a perspective view of a cassette

  holding the magnetic disk of Figure 2; Figure 7 is an enlarged section along the line VII-VII of Figure 1 (A); Figure 8 is an axial section of a portion of a magnetic disk, in a second embodiment of the invention;

  FIG. 9 is similar to FIG.

  a variant of the magnetic disk of Figure 1 (A); Fig. 10 is a partial plan view of a conventional flexible magnetic disk; and FIG. 11 is a section along the line XI-XI of

Figure 10.

  Reference is first made to FIGS. 1 (A) and 1 (B) to 7

  which represent a flexible magnetic disk according to the invention

  tion. The flexible magnetic disk carries the general reference

  1 and comprises a flexible magnetic sheet 2 and a central core 3 attached to a central portion of the magnetic sheet 2. The magnetic sheet 2 is formed of a synthetic resin and has two layers of a substance

  magnetic, formed on its opposite sides. The sheet

  Gnetic 2 has an outer circular periphery and a circular mounting hole 2a formed in a central portion. The central core 3 comprises a core base 4 formed of a

  magnetic substance, a hub 13 and a ring 27 of

  attached to the base 4 by molding a synthetic resin

  that with prisoner, and a cap 23 fixing

sheet, mounted on the hub 13.

  The base 4 of the core is in the form of a disc having an outer diameter slightly greater than that of the mounting hole 2a of the magnetic sheet 2, and has several fixing holes 5 (see FIG. 5) formed at a distance from each other. others in the form of a circumferential line, and separated alternately by relatively large distances and

  relatively low, near an outer circumferential edge

  born. Parts of the core base 4 placed between the adjacent fastening holes 5 separated by a relatively small distance are stamped and protrude downwardly below the plane of the base 4 and thus form grooves 6 at the top wall of the core. base 4 as shown on

Figure 4.

  The base 4 of the nucleus has a hole 7 formed in its part

  Central. The hole 7 of the base 4 has, along an inner edge

  dull, two parallel portions 8 and 8 'of edge disposed parallel to each other, two non-parallel portions 9 and 9' of edge having directions a little inclined by

  relative to the direction perpendicular to the parallel parts

  the edge 8 and 8 ', two surfaces or positioning edge portions 10 placed between the portion 8 and the ends

  adjacent non-parallel parts 9 and 9 'respectively

  ment, etc. The edge portions 10 of a pres-

  positioning position are arranged along two sides

  equilateral or isosceles triangle whose bisection

  trice goes through the center of the base 4 of the magnetic disk

  1 as shown in particular in FIG.

  a, a cavity 8'a is formed in the central portion of the other portion 8 'of parallel edge, and a folded tab 11 is formed at an edge of the cavity 8'a and protrudes upwardly. In addition, the other edge portions of the non-parallel portions 9 and 9 ', adjacent to the parallel portion 8', are bent back so that two edge portions 12 facing the parallel portion 8 are formed. The parts 12 are intended to support a spring plate 28 which is described in the following and

  so call them "spring support edges".

  The hub 13 of the central core 3 has a main part

  14 in the form of a ring, and a flange 15 which is formed in one piece of synthetic resin with the

  main part 14 and which exceeds radially towards the ex-

  a substantially central portion, in the axial direction from the outer periphery of the main portion 14. The flange 15 of the hub 13 has a circular outer periphery, and its outer diameter is substantially equal to the internal diameter of the mounting hole 2a of the leaf

magnetic 2.

  The main part 14 of the hub 13 has a hole of

  contact 16 formed there so that a shaft 44 of training

  disc, described below, can be housed temporarily

  porically in the hole 16 of the contact hub 13. The hole 16 of contact has a substantially hexagonal shape in plan, that is to say in the axial direction. In particular, an inner face of the contact hole 16 of the hub 13 has two parallel portions 17 and 17 'of face which are parallel to each other and have different extents from one another, two non parallel 18 face, placed opposite

  and arranged obliquely outwards from the ends

  opposite ends of the relatively short parallel portion 17 to the other longer parallel portion 17 ', and two additional face portions 19 disposed between the other ends of the non-parallel face portions 18 and opposite ends of the longer parallel portion

  17 'from the front. The end parts of the additional parts

  19, adjacent to the relative parallel part of the

  17 ', are arranged substantially perpendicularly to the parallel portions 17 and 17' of the face, and two spring-receiving slots 20 are formed in the hub 13 so that each of them opens into a

  substantially central part of each of the

  front end additional parts 19 and either

  placed in a direction substantially parallel to the parallel faces

  17 and 17 '. The outer end of each of the spring housing slots joins the flange 15 of the hub 13

of the central core 3.

  The main portion 14 of the hub 13 has a curved groove 21 formed in its upper wall along an edge of the contact hole 16, except in a part corresponding to

  the relatively long parallel face portion 17 '.

  The hub 13 having the construction described above

  It is formed on the base 4 and secured thereto by a prisoner molding so that a portion which is above the lower face of the flange 15 can protrude upwardly over an upper face. of the base 4 of the core, while the hub 13 is shown separated from the base 4 in Figure 5, and the open end portion of the

  central hole 7 of the base 4 can be coated at a location

  of the outer peripheral wall near the lower end of the main portion 14 of the hub 13 as

  shown in Figures 1 (A) and 1 (B).

  Whereas the inner edge of the central hole 7 of the base 4 is embedded at least partly in the hub 13 as

  shown in FIG. 7, the edge portions of

  10 are arranged so that they can protrude a little inwards from the locations

  near the lower extremities of the

  centrally, in the circumferential direction, non-parallel face portions 18 of the contact hole 16 of the hub 13. Furthermore, the spring support edges 12 of the base 4 join the substantially central portions of the spring housing slots 20, in the direction of

  the thickness of the slots 20, and an upper end face

  mity of the projection 11 of the base 4 of the core is exposed to a portion of the upper face of the main portion 14

  of the hub 13, between the outer periphery and the

  relatively relatively long 17 'of the main part 14.

  A shallow cavity 22 is formed in a

  portion of the bottom wall of the main portion 14 of the hub 13 which is contiguous with the relatively long parallel face portion 17 'and which is disposed from the parallel face portion 17' to the outer periphery of the main portion 14 as shown in Figures 1 (A),

1 (B) and 5.

  The sheet fixing cap 23 for the central core 3 comprises a mounting portion 24 in the form of a ring having an inner diameter substantially equal to the outer diameter of the main portion 14 of the hub 13, and a flange portion 25 forming the outer circular periphery which is made of a single piece of synthetic resin with the mounting portion 24 and protrudes laterally from a lower end portion of that mounting portion 24. The fastening cap 23 has a central hole 26. This hole 26 has an internal diameter, measured at the lower portion 26a, which is greater than that of the

upper part remaining.

  The sheet fixing cap 23 which has the

  described truction is fixed on the hub 13 by a device

  suitable, for example by gluing or ultrasonic welding.

  sound in a state such that the main portion 14 of the hub 13 is mounted in the central hole 26 of the cap 23 while the mounting hole 2a of the magnetic sheet 2 is placed around the flange 15 of the hub 13. It should be noted that the flange 15 of the hub 13 is placed in the part 26a of

  relatively large diameter of the hole 26 of the cap 23.

  The cap 23 and the assembly formed by the base 4 of the core and the hub 13 are mutually fixed, an inner peripheral portion of the magnetic sheet 2 placed

  around the mounting hole 2a being disposed between them.

  The spacer ring 27 of the central core 3 has an outer diameter slightly smaller than that of the base 4 of the core and is formed on the underside of the base 4, being coaxial therewith, by molding with a prisoner although it is shown separated from the base 4 in FIG. 5. The spacer ring 27 has a lower end face which is below the lower face of the hub 13. It should be noted that the ring 27 spacer is

  made integral with base 4 because it penetrates partially

  in the fixing holes and the formed grooves 6

in the base 4.

  The spring metal plate 28 of the central core

  3 has a main portion 29 having a sensory shape

  1 of the spring plate 28 has two cavities or cutouts 31a at locations near the opposite longitudinal ends of a lower end 31 and protrudes from the lower end upwards, and a portion 32 disposed between the cutouts 31a (hereinafter referred to as "center piece

  lower end ") and laterally bent at the end

  lower half 32a (this part being called "part

folded "), obliquely downwards.

he

  The spring metal plate 28 which has this

  truction is supported on the hub 13, the core base 14 and the sheet attachment cap 23 in the following manner. The support portions 30 of the spring plate 28 are in particular placed on the parts of the

  upper side of the base 4 which are arranged lateral-

  relative to the spring support edges 12 of the base 4 and are exposed in the slots 20 of the hub 13 while the opposite ends of the main portion 29 of the spring plate 28 are placed between the inner side faces of the slots 20 , near the non-parallel face portions 18 of the hole 16 of the hub 13, and the spring support edges 12 of the base 4. The folded portion 32a of the plate 28 is thus directed away from the non-parallel face portions 18 of the hole 16 of the hub

  13, and the support portions 30 of the plate 28 are dis-

  placed below an upper face of part 26a of

  larger diameter of the hole 26 of the fixing cap 23.

  Accordingly, the support portions of the plate 28

  spring are held in the vertical or lateral direction

  between the base 4 and the cap 23 so that the plate 28 can not move in a lateral or vertical direction. Furthermore the longitudinal displacement of the plate 28 is almost prevented by the outer end faces of the spring housing slots 20 of the hub 13, and the displacement of the plate 28 in the thickness direction is prevented because the longitudinal portions end of the main portion 29 of the plate 28 are held against the support edges 12 of the base 4 and the inner side faces of the slots 20 near the

  non-parallel face portions 18 of the hole 16 of the hub 13.

  The spring plate 28 is thus placed in a

  hole 16 of the hub 13 opposite the edge portions of

  10 of the base 4 which exerts a pressure, from the inner face of the bent portion 32a, to the lower end, this part being turned from the opposite side to

  that of the positioning parts.

  The magnetic disk 1 having this construction is

  is housed in a cassette 33 of magnetic disk.

  The cassette 33 has a cassette housing 34 in the form of a relatively thin box consisting of two halves 35 and 36 coupled so that they are solid with each other. Two walls of the housing 34 have, opposite in the direction of thickness, drive shaft holes 37 drilled coaxially at substantially central locations, and two head-passage windows 38 are formed at walls facing the housing 34 which are close to a side edge

  of the housing 34, while another pair of posi-

  39 and 39 'are formed at locations of the two walls of the housing which are close to the opposite edges of the housing 34 on either side of said first lateral edge. A shutter 40 intended to open and close the windows 38 of the housing 34 is supported so that it slides

  along the first side edge of the housing 34.

  The magnetic disk 1 is housed so that it can rotate in the housing 34, with the construction described above. The central core 3 of the magnetic disk 1 is

  exposed to the outside through the holes 37 of the shaft passage.

  It should be noted that when the cassette 33 is not used, the shutter 40 is in its closed position in which it closes the windows 38 of the magnetic disk cassette 33 but, when the cassette 33 is mounted on a set drive drive not shown,

  it is moved by a suitable device not shown

  felt towards its open position in which it opens the windows 38 of the cassette 33 as shown on the

figure 6.

  Reference is now made to Figures 1 and 7; a

  recording-reading section of a set of training

  magnetic disk is designated by the reference 41

  and has a pin 42 connected so that it is

  drag in rotation by a motor not shown and having

  a turntable or turntable 43, a shaft 44 of

  disc stretching protruding from the center of the turntable 43

  and having an upper portion 45 of truncated configuration

  a magnet 46 fixed to an upper face of the plate 43 and a cassette holder 47 for removably supporting a cassette 33 of magnetic disk. It should be noted that the portion of the shaft 44 other than the upper portion 45 has a diameter slightly greater than that of the circle inscribed in the spring plate 28 and the two positioning portions 10 formed on the hole 16 of the

central core 3.

  Thus, when the cassette holder 47 on which the cassette 33 is supported is moved to a cassette mounting position of the section 41, the positioning

  of the case 34 of the cassette 33 is made by a device

  positioning rod not shown, and the shaft 44 of

  disk drag is introduced into the hole 16 of the core

  center 3 of the magnetic disk 1. In particular, the case

  This disk 33 is moved to the pin 42 under conditions such that the contact hole 16 of the central core 3 of the disk 1 is placed in front of the shaft 44 and coaxially with it, and when the cassette 33

  comes in position a little ahead of the mountain position

  ge, the upper portion 45 of the shaft 44 enters the mounting hole 16, and a portion of the edge of the lower side of the contact hole 16 and the folded portion 32a of the central piece 32 of the lower end of the plate 28 of

  spring are in contact with the inclined face 45a of the

  upper portion 45 of the disk drive shaft 44 as shown in Fig. 1 (A). As a result, the main portion 29 of the spring plate 28 is pushed back by the upper portion 45 of the shaft 44 and deforms away from the positioning portions of the hole 16 so that the core 3 is pushed back into the direction that deforms the plate 28 and that the positioning parts 10 are

  pushed against the outer periphery of the drive shaft 44. It should be noted that the folded portion 32a of the central piece 32

  the spring plate 28 then advances into the cavity 22 formed in the bottom wall of the hub

  13 as shown in Figure 1 (B).

  Then, just before the cassette 33 reaches the mounting position, the central core 3 is placed on the turntable 43. Next, the spacer ring 27 of the core 3 is brought into contact with the upper face of the turntable 43, and the base 4 formed of a magnetic substance is attracted to the magnet 46 so that the core 3 is permanently mounted on the plate 43 as shown in Figure 1 (B). As a result, the magnetic disk 1 is firmly mounted on the pin 42, and the introduction of the shaft 44 in the hole 16 of contact of the core 3 of the disk 1 is thus completed. Under these conditions, the two positioning portions of the contact hole 16 of the core 3 are pushed by the restoring force, of suitable intensity, against the outer periphery of the shaft 44, except in its upper part 45, although that the centering of the disc

  magnetic 1 relative to the pin 42 is provided.

  When the magnetic disk 1 is firmly mounted on the pin 42 in this way, in an initial step, the lower end of the plate 28 contacts the upper portion 45 of the shaft 44. However, in this case, as the central portion 32a of the lower end of the plate 28 is bent on the opposite side to that of the positioning portions 10 of the hole 16, no edge of the plate 28 comes into contact with the upper portion 45 of the shaft 44. Thus, when the lower end of the spring plate 28 is in contact with the upper portion 45 of the shaft 44, it does not bite at all in the outer face of the upper portion 45 and slides regularly.

  against the inclined face 45a of the portion 45.

  Reference is now made to Figure 8; it represents

  a flexible magnetic disk according to a second embodiment of the invention. The magnetic disk of this embodiment is similar in general to that of the first embodiment described above and differs only in the configuration of a lower end portion of a spring plate of a central core corresponding. Thus, the parts or elements of the embodiment shown in FIG. 8 which are similar to the previous embodiment described with reference to FIGS.

  res 1 (A) and 1 (B) to 7 bear the same numerical references

  and the corresponding description is deleted in order to

  that it is not redundant. This also applies to

  description of a variant shown in FIG. 9,

described below.

  A metal spring plate 28 of the magnetic disk

  FIG. 8 has two cutouts 48 formed in a central piece 32 of its lower end, with an intermediate neck-shaped connecting portion 49, so that the central piece 32 and the connecting portion 49 may have, in front elevation, a T shape returned as shown in Figure 8. The central piece 32 is thus connected to the rest of the party

  29 of the plate 28 by the connecting part 49

* ment which has a reduced width. Thus, the constant elasticity

  plate 28 can be set to a suitable value.

  thanks to the connection part 49, despite the presence

  this of a folded portion 32a on the central piece 32, to the ex-

  lower tremity. In particular, when part 32a

  folded in the direction of the thickness of the plate 28 is formed

  mated on this plate 28, the rigidity of the plate 28 in the direction of the thickness increases significantly so that the

  elastic constant of the plate 28 increases. As a result

  this, the resistance opposed to the introduction of the shaft 44 in the hole 16 of the central core 3 increases, and the mounting of the magnetic disk 1 can easily be incomplete or the centering of the disk 1 may be inaccurate. This problem is solved by using a spring metal plate

  thinner than the one used as a standard

  spring f described above, for the realization

  of the spring plate 28 of the first embodiment.

  However, this increases the possibilities of deformation of the material itself and, therefore, it is possible that a fold may be formed at each of the locations of the main portion 29 of the spring plate 28 at the boundaries between

  the opposite end parts to which the main part

  Cipal 28 is supported on a hub 13 or a base 4 and an intermediate portion between the opposite end portions. In the magnetic disk of the second

  however, like the cutouts 48 describing

  previously are placed in the central part 32 of the main part 29 of the spring plate 28, the

  the rigidity of the plate parts 28 other than the central part

  tral 32 is slightly increased. Thus, a thick material

  similar to that of the classical spring plate

  can be used for forming the plate 28.

  Reference is now made to Figure 9; it represents

  is a variant of the magnetic disk of the first embodiment described above. The magnetic disk according to

  the variant differs from that of the first mode of

  by the contour of a bent part of the center piece, at the lower end of the spring plate

a central core.

  In particular, a folded portion 50 of the central piece 32 of the spring metal plate 28 has a portion 50a protruding obliquely and laterally downwards from the lower end of the central piece 32 and corresponding to the folded portion 32a of the plate 28 of the first embodiment described above, and a portion 50b protruding laterally obliquely upward from the lower end of the portion 50a. The folded portion 50 is therefore substantially V-shaped in lateral elevation as shown in FIG. 9. Thus, the folded portion 50 of the plate 28 does not have an edge at its end.

  lower end. Consequently, the penetration

  the lower end of the plate 28 in an inclined face 45a or an upper face 45b of a part

  upper 45 of a disk drive shaft 44, when

  that the plate 28 comes into contact with the upper part

  of the shaft 44, can be avoided very safely.

  It should be noted that, although in the modes of

  previously described, the central core is formed of a core base of a magnetic substance, a synthetic resin hub, having a contact hole, etc., and

  pressure surfaces formed on the base in such a way that

  extend beyond the inner periphery of the hub contact hole, the pressure surfaces can also be formed integrally with the hub or, in other words, they can be made directly to the hub

  the inner periphery of the contact hole.

  Of course, various modifications may be made by those skilled in the art to the magnetic disks which have just been described as examples only.

  limiting, without departing from the scope of the invention.

Claims (3)

  1. Flexible magnetic disk, characterized in that it comprises:   a flexible magnetic sheet (2) having a peripheral   circular outer plate, an elongated metal spring plate (28) having a main portion (29) and two support portions (30) at both ends of the main portion, and a hub attached to the flexible magnetic sheet at the center of the sheet and having a hole arranged axially to   through the hub, the latter having two positional surfaces   ment (10) occupying locations spaced from each other about a central axis of the hole, the hub having two seats for accommodating the support portions of the   elongated metal spring plate (28) so that   it is supported by the hub in such a way that its main part faces the pair of positioning surfaces, a portion (32a) contiguous with the lower end of the main portion (29) of the spring metal plate (28) being folded on the opposite side to the central axis the hole.   Disk according to Claim 1, characterized in that the main part (29) of the spring metal plate (28) has two cutouts (31a) on both sides of the   folded portion (32a), each of the cuts exceeding   above the lower end of the main portion (28). Disc according to claim 1, characterized in that the folded portion of the spring metal plate is connected to the main part by a narrow neck portion delimited by cutouts (48) formed on both sides of the folded portion. of the spring metal plate.