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Claims  |
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I claim as my invention:
1. A flexible magnetic disk cassette comprising:
(a) a flexible magnetic disk;
(b) a center core disk having a center hollow and raised fringe, and being
attached at a center of said flexible magnetic disk with said raised
fringe; and
(c) a cover having an upper half and lower half containing said flexible
magnetic disk with said center core disk, said lower half having a driving
hole a little larger than an outer diameter of said center hollow of said
center core disk.
2. A flexible magnetic disk cassette as claimed in claim 1, wherein said
upper half of said cover is provided with a ring-shaped projection having
a diameter a little smaller than an inner diameter of said center hollow
of the center core disk.
3. A flexible magnetic disk cassette as claimed in claim 2, wherein said
raised fringe and said ring-shaped projection are so designed as to
prevent said flexible magnetic disk from undesirable positioning within
said cover when said flexible magnetic disk is not ready for use.
4. A flexible magnetic disk cassette comprising:
(a) a flexible magnetic disk;
(b) a pan-shaped one-piece center core disk of magnetic material having a
center hollow and raised fringe, said center core disk being attached at a
center of said flexible magnetic disk by said raised fringe; and
(c) a cassette cover having an upper half and lower half containing said
flexible magnetic disk with said center core disk, said lower half having
a driving aperture larger than an outer diameter of said center hollow of
said center core disk.
5. A magnetic disk cassette comprising:
a flexible magnetic disk;
a center core disk attached and positioned in an aperture at a center of
the flexible magnetic disk;
the center core disk having an annular center hollow; and
a cover having an upper wall and lower wall between which the flexible
magnetic disk is positioned, the upper wall having a ring-like projection
receivable in the annular hollow of the center core disk when the magnetic
disk is assembled in the cover, the lower wall having a driving hole for
access to the center core disk by a driving mechanism.
6. A cassette according to claim 5 wherein the center core disk at least
partially extends into the driving hole, the driving hole having a
diameter slightly larger than an outer diameter of the annular hollow of
the center core disk.
7. A magnetic disk cassette, comprising:
a flexible magnetic disk;
a center core disk having a center hollow and a ring-like raised fringe,
said raised fringe providing an attachment surface means which together
with an adhesive attachs the center core disk to the flexible magnetic
disk in a central aperture thereof; and
a cover having an upper wall and lower wall containing the flexible
magnetic disk with the center core disk, the lower wall having a driving
hole positioned for permitting access to drive the center core disk from
an external driving means.
8. A flexible magnetic disk cassette, comprising:
a flexible magnetic disk;
a center core disk having a center hollow and raised fringe and being
attached to a center of said flexible magnetic disk with said raised
fringe;
a cover having an upper half and lower half containing said flexible
magnetic disk with said center core disk, said lower half having a driving
hole for access by a driving means to the center core disk;
first and second disk-like cleaning fabrics positioned between the magnetic
disk and the respective upper and lower walls; and
the upper and lower walls and the first and second cleaning fabrics having
a magnetic head opening means therein to permit access to a recording
surface of the magnetic disk by a magnetic head.
9. A flexible magnetic disk cassette system, comprising:
a cassette formed of a flexible magnetic disk having a pan-shaped center
core disk forming a center hollow and outer convex portion and having a
raised flange upwardly of a lower surface of the center core disk, the
center core disk being attached at a center of the flexible magnetic disk
with said raised fringe, and a cover having an upper wall and lower wall
containing the flexible magnetic disk, the lower wall having a driving
hole aligned with the center core disk, said center core disk having a
central positioning aperture and an offset driving aperture; and
a driving and recording/reproducing system means for receiving the
cassette, said system means having driving means engageable with the
center core disk.
10. A system according to claim 9 wherein a ring-like projection extends
from an inside surface of the upper wall of the cassette cover and is
engageable in a center hollow of the center core disk.
11. A flexible magnetic disk cassette driving apparatus for rotating a
flexible magnetic disk having a center core and positioned within the
cassette, comprising:
driving means coupled with the center core of the flexible magnetic disk
for rotating it at a predetermined speed;
cassette supporting means mounted on a chassis for receiving and
positioning said flexible magnetic disk cassette;
cassette pressing means for depressing said cassette on said cassette
supporting means; and
positioning means on said driving means for positioning an inner surface of
an upper wall of said disk cassette.
12. The driving apparatus of claim 11 wherein the cassette supporting means
comprises a plurality of spring biased members pressing down on the upper
wall of the cassette at outer regions thereof.
13. A driving apparatus according to claim 11 wherein said positioning
means for positioning the inner surface of the upper wall of the disk
cassette comprises an end of a center positioning pin positioned within a
central aperture of the central core.
14. The apparatus of claim 13 wherein the center positioning pin has a
hemispherical top surface.
15. A flexible magnetic disk cassette system comprising:
a disk cassette formed of a flexible magnetic disk positioned within a
cover having upper and lower walls closely spaced to the flexible magnetic
disk, said flexible magnetic disk having a central aperture with a
corresponding aperture in the lower wall of the disk cassette;
a drive mechanism for receiving the disk cassette thereon and having a pin
associated therewith which is positioned through the aperture of the lower
wall of the cassette and through the aperture of the magnetic disk; and
an end of the pin abutting against an inner surface of the upper wall of
the cassette when the cassette is in position on the driving apparatus so
as to insure a given position of the upper wall relative to the lower wall
so as to prevent any undesired warping contact of the inner surfaces of
the upper and lower walls with the flexible magnetic disk.
16. A system according to claim 14 wherein biasing means are provided so as
to press downwardly at outer peripheral edges of the cassette when it is
in position on the driving apparatus.
17. The system of claim 16 wherein structural elements are provided in the
cassette disk such that when the outer peripheral biasing members are
pressing down and the center pin presses up at the inner surface of the
upper wall, the upper wall becomes substantially flat and the lower wall
becomes substantially flat so as to prevent any warping contact between
the upper and lower walls and the flexible magnetic disk.
18. A magnetic disk cassette, comprising:
a flexible magnetic disk;
a cover having upper and lower walls between which the flexible magnetic
disk is positioned, said lower wall having a driving hole means therein
through which the flexible disk may be driven;
a pan-shaped center-core disk having magnetic material therein and forming
a center hollow and outer convex portion at a central portion of the
magnetic disk and having in a lower surface of the pan-shaped disk a
center aperture means for receiving a center positioning pin and a driving
aperture means for receiving a driving pin of said drive device; and
the center aperture means being slightly offset from a center point of the
flexible magnetic disk and being designed slightly larger than the center
positioning pin such that when the spring biased driving pin engages an
edge of the driving aperture means the center positioning pin of the drive
device abuts against an edge of the center aperture means and a central
axis of the center positioning pin will lie on the center point of the
magnetic disk.
19. A magnetic disk cassette, comprising:
a flexible magnetic disk;
a cover having upper and lower walls between which the flexible magnetic
disk is positioned, said lower wall having a driving hole means therein
through which the flexible disk may be driven;
a pan-shaped center-core disk of magnetic material is positioned centrally
on the magnetic disk and has an outer convex portion receivable in and a
diameter slightly smaller than said driving hole means in the lower wall
and a center hollow having an inner diameter slightly larger than a
diameter of a projection from said upper wall receivable with the center
hollow.
20. A cassette according to claim 19 wherein the pan-shaped center-core
disk constructed of magnetic material is mounted on a central aperture of
the flexible magnetic disk.
21. A cassette according to claim 19 wherein the center-core disk has a
raised fringe at which it is attached to the flexible magnetic disk.
22. A magnetic disk cassette according to claim 19 wherein the projection
at the upper wall is circular and in the form of an annular ring.
23. A magnetic disk cassette, comprising:
a flexible magnetic disk;
a cover having upper and lower walls between which the flexible magnetic
disk is positioned, said lower wall having a driving hole means therein
through which the flexible disk may be driven; and
a pan-shaped center-core disk having a hollow central portion which
receives a projection from said upper wall, said pan-shaped center-core
disk being provided at a central portion of the magnetic disk.
24. A cassette according to claim 23 wherein the pan-shaped center-core
disk is of a magnetic material, has a raised fringe relative to a lower
surface, and the magnetic disk has an aperture within which the pan-shaped
center-core disk is positioned therein, and the magnetic disk attaching to
the center-core disk at said fringe by adhesive. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a flexible magnetic disk cassette capable of
being used for the recording and reproducing of various analog and digital
signals, and a recording and/or reproducing apparatus for the flexible
magnetic disk cassette. More particularly, this invention is concerned
with a disk cassette having a cassette cover in which is rotatably
accommodated a recording and reproducing disk having flexibility such as a
sheet-like magnetic disk (magnetic sheet), and a recording and/or
reproducing apparatus for the same.
Description of the Prior Art
Referring to FIG. 1, there is shown a conventional recording and
reproducing disk cassette designated by the reference numeral 1, which
comprises a flat cassette cover 4 in the form of a rectangular
parallelepiped composed of upper and lower halves 2 and 3, and a
sheet-like flexible magnetic disk (magnetic sheet) 5 accommodated
rotatably within the cassette cover 4. The magnetic disk 5 has a magnetic
layer formed on both surfaces thereof, and on the central part thereof
there is a center core disk 6 consisting of a circular plate stuck thereon
with adhesive or the like. In the central part of the center core disk 6
there is formed a rotary shaft insertion opening 7.
When the disk cassette 1 is installed (loaded) onto a magnetic recording
and/or reproducing apparatus (not shown), a rotating carriage 8 engages in
a center opening 3a of the lower half 3 and at the same time a rotary
shaft 9 is inserted in the rotary shaft insertion opening 7. In this state
the center core disk 6 is attracted and fixed onto the rotating carriage 9
by means of an attracting member (not shown) consisting of a magnet. In
this case, the magnetic disk 5 is disposed centrally in its thickness
direction in consideration of the construction and dimension of the
cassette cover 4. On the other hand, the magnetic head 11 is inserted into
a head insertion opening 10 formed in the lower half 3 and then is brought
into contact with the magnetic surface of the magnetic disk 5.
In such a loaded state, the center core disk 6 is rotated together with the
rotating carriage 9 by means of a driving unit such as a motor 12,
whereupon the magnetic disk 5 is rotated within the disk cassette 1. In
association therewith the magnetic head 11 is moved in a radial direction
of the magnetic sheet 5 (namely in the direction of arrow a in FIG. 27),
thereby performing a desired recording or reproducing operation.
In the disk cassette 1 of this sort, in order to prevent the peripheral
edge portion of the magnetic disk 5 from striking against and being bent
by the upper and lower halves 2 and 3, a ring-like projection 13 is formed
on the inner surface of the upper half 2 to restrict the displacement of
the center core disk 6 relative to the cassette cover 4. The disk cassette
is installed, for example, in the following dimensional relation relative
to the cassette cover 4, the projection 13, the center core disk 6 and the
magnetic disk 5. The thickness l.sub.1 of the cassette cover 4 is 3.4 mm;
the plate thickness l.sub.2 of the upper half 2 is 0.8 mm; the plate
thickness l.sub.3 of the center opening portion 3a of the lower half 3 is
1.3 mm; the projecting length l.sub.4 of the projection 13 is 0.5 mm; the
spacing l.sub.5 between the magnetic disk 5 and the projection 13 and the
spacing l.sub.5 between the magnetic disk 5 and a ring-like projection 14
of the lower half 3 are each 0.4 mm; the thickness l.sub.6 of the center
core disk 6 is 0.5 mm; and the spacing l.sub.7 between the inner surface
of the upper half 2 and the center core disk 6 is 0.4 mm (see FIG. 2).
Thus, the magnetic disk 5 is disposed centrally in the thickness direction
of the cassette cover 4.
However, when the disk cassette 1 is not installed on a magnetic recording
and/or reproducing apparatus, that is when the disk cassette 1 is not in
use, if the magnetic disk 5 and the center core disk 6 move toward the
lower half 3 by virtue of their own weights as indicated with a dot-dash
line in FIG. 2, there is formed a gap of about 0.3 mm between the tip end
of the projection 13 of the upper half 2 and the upper surface of the
center core disk 6. In the presence of this gap, the movement of the
center core disk 6 is no longer restricted by the projection 13, that is
the center core disk 6 and the magnetic disk 5 move freely in the
horizontal direction within the cassette cover 4, so that the peripheral
edge portion of the magnetic disk 5 may strike against the side of the
cassette cover 4 and be bent thereby. Once the peripheral edge portion of
the magnetic disk 5 is bent, it is no longer possible to perform a good
recording and reproducing operation in the vicinity of the bent peripheral
edge portion.
Such an inconvenience is overcome by making larger thickness l.sub.5 of the
center core disk 6 and thereby making larger the overlapping length
l.sub.8 between the projection 13 and the center core disk 6 at the time
of installing of the disk cassette 1. But this has not been realized
because of the resulting very narrowed space (particularly in the
thickness direction) within the cassette cover 4 and because of, as
previously noted, the requirement that the magnetic disk 5 must be
disposed centrally in the thickness direction of the cassette cover 4.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a flexible magnetic disk
cassette which overcomes the foregoing problems associated with the prior
art.
More specifically, it is an object of the present invention to provide a
flexible magnetic disk cassette in which, even while the disk cassette is
not in use, the movement of the center core disk and hence of the magnetic
disk are surely restricted within a predetermined range.
It is another object of the present invention to provide a flexible
magnetic disk cassette which has a relatively flat shape.
In accordance with an aspect of the present invention, a flexible magnetic
disk cassette includes a flexible magnetic disk, a center core disk having
a center hollow and raised fringe, and being attached at a center of said
flexible magnetic disk with said raised fringe. A cover is provided having
an upper half and a lower half for containing the said flexible magnetic
disk with said center core disk, said lower half having a driving hole a
little larger than an outer diameter of said center hollow of said center
core disk.
Other objects, features and advantages according to the present invention
will become apparent from the following detailed description of an
illustrative embodiment shown in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal sectional view schematically illustrating a
conventional disk cassette which is installed on the magnetic recording
and/or reproducing apparatus;
FIG. 2 is an enlarged sectional view taken on line II--II of FIG. 1;
FIG. 3 is an exploded perspective view of a flexible disk cassette
according to the embodiment of this invention;
FIG. 4 is a perspective view of an upper half of a cassette cover viewed
from below;
FIG. 5 is a plan view of a center core disk viewed from a recessed side
thereof;
FIG. 6 is a perspective view of the disk cassette from below;
FIG. 7 is a longitudinal sectional view of a main part of the disk cassette
showing its central portion, partly omitted;
FIG. 8 is a longitudinal sectional view of a main part of the disk cassette
showing a guide means comprising a guide groove formed in the cassette
cover and a pawl-like projection formed on a shutter;
FIG. 9 and FIG. 10 are each longitudinal sectional views of a main part of
the disk cassette showing a modification of the guide means;
FIG. 11 is a longitudinal sectional view of a main part of the disk
cassette showing an erroneous erase preventing detent formed on the
cassette cover;
FIG. 12 is an exploded perspective view showing the disk cassette and a
main part of a recording and/or reproducing apparatus according to the
embodiment of this invention, onto which is to be installed the disk
cassette;
FIG. 13 is a plan view of the above apparatus with a cassette pressure
member removed;
FIG. 14 is a plan view of the apparatus with the cassette pressure member;
FIG. 15 is a sectional view taken on line XV--XV of FIG. 14;
FIG. 16 is a sectional view taken on line XVI--XVI of FIG. 14;
FIG. 17 is a sectional view taken on line XVII--XVII of FIG. 14;
FIG. 18 is an exploded perspective view showing a mounting state of a rotor
of a motor, a spacer, a leaf spring to which is attached a spring-biased
driving pin, a yoke, and a motor cover;
FIG. 19 is a sectional view taken on line XIX--XIX of FIG. 13;
FIG. 20 and FIG. 21 are sectional views similar to FIG. 19 illustrating the
operation of the spring-biased driving pin;
FIG. 22 is an exploded perspective view of a main part of a head moving
mechanism;
FIG. 23 is a perspective view of a rotational position detecting mechanism
for the motor shaft of a step motor;
FIG. 24 is a sectional view taken on line XXIV--XXIV of FIG. 22;
FIG. 25 is a sectional view taken on line XXV--XXV of FIG. 24;
FIG. 26 is a longitudinal sectional view of a main part illustrating a
correlative operation between the erroneous erase preventing detent of the
disk cassette and an erroneous erase preventing detent detection member;
FIG. 27 is a schematic side view illustrating the principle of a correcting
operation against an inward warp of upper and lower plates of the cassette
cover; and
FIG. 28 is a plan view of the center core disk in a positioned state with
the motor shaft and a spring-biased driving pin respectively inserted in
the motor shaft insertion opening and the spring-biased driving pin
insertion opening both formed in the center core disk.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of this invention will be described with reference to FIGS. 3
to 28.
In this embodiment, a flexible magnetic disk cassette containing a
sheet-like flexible magnetic disk is installed onto a recording and/or
reproducing apparatus and the recording and/or reproducing operation is
performed.
First, an explanation is here given concerning a disk cassette 26
comprising a flexible magnetic disk 21 and a cassette cover 22. As shown
in FIG. 3, the flexible magnetic disk 21 is formed of, for example, a thin
disk-like high polymer film having a thickness of 0.4 mm, and a magnetic
layer uniformly formed on both surfaces to which a recording/reproducing
magnetic head is to be brought into contact. At the center of the flexible
magnetic disk 21 there is formed a circular center opening 21a (See FIG.
7) at which there is attached a center core disk 23 made of a
ferromagnetic material such as iron. The center core disk 23 is formed
from a flat disk by pressure and, as shown in FIG. 3 and FIG. 7, on one
side thereof there is formed a center hollow 23a, and on the other side
thereof there is formed a disk-like convex portion 23b. At the peripheral
edge portion of the center core disk 23, there is formed a ring-like
raised fringe 23c. Thus, the center core disk 3 is constructed in the form
of a pan. As shown in FIG. 7, a ring-like raised double-sided adhesive
sheet 27 is bonded to the raised fringe 23c of the center core disk 23,
and the peripheral edge portion of the center opening 21a of the magnetic
disk 21 is bonded to the double-sided adhesive sheet 27, whereby the
center core disk 23 and the flexible magnetic disk 21 are joined together
integrally.
At a nearly central part of the center cord disk 3, a square center
aperture 24 having a V-shaped corner is formed as a motor shaft insertion
aperture, and at a position which is distant by a predetermined distance
from the center aperture 24, a rectangular driving and positioning
aperture 25 is formed as a positioning pin insertion aperture. As clearly
shown in FIG. 5, the center 0.sub.1 of the center aperture 24 is off the
center 0.sub.2 of the center core disk 23 and the flexible magnetic disk
21, and is slightly distant by a predetermined distance toward the driving
and positioning aperture 25. The center aperture 24 and the driving and
positioning aperture 25 are formed so that a pair of diagonal lines
d.sub.1 and d.sub.2 of the center aperture 24 are each parallel with short
and long side portions 25b and 25a of the driving and positioning aperture
25, respectively. Furthermore, the length of one side of the center
aperture 24 is slightly larger than the diameter of the motor shaft so
that the motor shaft when fitted in the center aperture 24 provides a
slight looseness. The reason why the center of the center aperture 24 is
apart from the center of the center core disk 23, as will be described in
detail later, is that it is intended to coincide the center of the motor
shaft fitted in the center aperture 24 of the center core disk 23 with the
center of the flexible magnetic disk 21 when the disk cassette 26 is
installed onto the recording and/or reproducing apparatus.
On the other hand, the cassette cover 22 for accommodating the flexible
magnetic disk 21, as shown in FIG. 3, is composed of an upper half 22a and
a lower half 22b which are made of, for example, an injection molded
article from ABS resin containing an antistatic agent. The outer
peripheral portions of the upper and lower halves 22a and 22b are welded
to each other to form a flat rectangular parallelepiped as a whole. At a
nearly central part of lower half 22b there is formed a circular center
opening as a driving hole 28, and at the peripheral edge portion of the
driving hole 28 and on the inner surface of the lower half 22b there is
integrally formed a ring-like projection 29. As shown in FIG. 6, the
convexed portion 23b of the center core disk 23 is fitted in the driving
hole 28 in a state which is slightly loose. On the inner surface of the
central part of the upper half 22a, as shown in FIG. 4 there is integrally
formed a ring-like projection 30, and also around the projection 30 there
is integrally formed a ring-like projection 31 which is concentric with
the projection 30. The projecting length of the projection 30 is longer
than that of the projection 31 and hence, as shown in FIG. 7, the
projection 30 extends beyond the projection 31 and projects on the inner
surface side of the lower half 22b. The ring-like projection 30 is
inserted in the center hollow 23a of the center core disk 23 in a state
which is slightly loose.
Now, the cassette case 22, the upper and lower halves 22a and 22b, the
center core disk 23, and the ring-like projection 30 of the upper half 22a
are, for example, in the following dimensional relation. The thickness
L.sub.1 of the cassette case 22 is 3.4 mm, the thickness L.sub.2 of an
upper plate 22c and that of a lower plate 22d of the upper and lower
halves 22a and 22b are each 0.8 mm respectively, the thickness L.sub.3 of
the upper plate 22c of the upper half 22a of the portion surrounded with
the projection 10 is 1.0 mm, the projection length L.sub.4 of the
projection 30 is 1.5 mm, the thickness L.sub.5 of the center core disk 3
is 0.3 mm, the thickness L.sub.6 of the lower plate 22d of the lower half
22b adjacent to the center opening 28 is 1.3 mm, and the height L.sub.7 of
the center core disk 23 is 1.8 mm (See FIG. 7).
When the disk cassette 26 is installed onto the recording and/or
reproducing apparatus as will be described later, the flexible magnetic
disk 1 is disposed nearly centrally in the direction of the thickness of
the cassette cover 22 as shown by the solid line in FIG. 7 and then is
rotated. In this case, the distance L.sub.8 between the fringe 23c of the
center core disk 23 and the inner surface of the upper half 22a and the
distance L.sub.9 between the flexible magnetic disk 21 and the projection
29 of the lower half 22b are each 0.4 mm. The distance L.sub.10 between
the tip end of the projection 30 of the upper half 22a and a lower surface
23d of the center disk is 0.4 mm, and the distance L.sub.11 between the
outer surface of the lower half 22b and the lower surface 23d of the
center core disk 23 is 0.2 mm (See FIG. 7). When the disk cassette is not
in use, the center core disk 33 and the flexible magnetic disk 21 are
placed on the lower half 22b by virtue of their own weights, for example,
as shown by dot-dash line in FIG. 7. In this case, the tip end portion of
the projection 30 of the upper half 22a and the projection 29 of the lower
half 22b overlap with each other by 0.4 mm (distance L.sub.12) so even if
the center core disk 23 is moved, a part of the center hollow 23a of the
center core disk 23 is sure to engage the projection 30. Thereby the
looseness in a planar direction of the center core disk 23 and hence the
flexible magnetic disk 21 is kept within a predetermined range, and
therefore the projection 30 and the center hollow 23a of the center core
disk 23 are not disengaged from each other along with the displacement of
the center core disk 23. In case the disk cassette 26 is turned upside
down from the state shown in FIG. 7 and consequently the center core disk
23 is placed on the upper half 22a by virtue of its own weight, the
projection 30 comes into a completely fitted state within the center
hollow 23a of the center core disk 23, so that, as in the aforesaid case,
the amount of displacement of the center core disk 23 and hence of the
magnetic disk 21 is kept within a predetermined range.
In the disk cassette 26 having the above construction, the amount of
displacement of the center core disk 21 and of the flexible magnetic disk
21 can be regulated exactly by the projection 30 until a gap between the
upper and lower plates 22c and 22d becomes wider by 2.2 mm (the sum of the
overlapping length of 0.4 mm and the center core disk height os 1.8 mm)
while the upper and lower halves 22a and 22b are moved from the state
shown in FIG. 5 toward the exterior, namely in the direction in which the
upper plate 22c and the lower plate 22d go away from each other.
On the inside surfaces of the upper and lower halves 22a and 22b there are
integrally formed four arcuate ribs 13 and 14 respectively extending
concentrically with the driving hole 28 at regular intervals. When the
cassette cover 22 is assembled, the ribs 33 of the upper half 22a and the
ribs 34 of the lower half 22b are disposed on the same circumference, and
at the same time the ribs 33 and 34 are positioned adjacent to each other
at the four corners of the cassette cover 22 whereby there is formed
substantially one pair of ribs at each corner. The flexible magnetic disk
21 is disposed so as to be surrounded with these ribs 33 and 34. The ribs
33 abut the inner surface of the lower plate 22d of the lower half 22b,
and the ribs 34 abut the inner surface of the upper plate 22c of the upper
half 22a. Accordingly, the cassette cover 2, which is flat and easy to
deform even by a small external force, is mechanically reinforced.
Furthermore, in order to avoid possible damage or wear of the flexible
magnetic disk 21, a magnetic disk protecting non-woven fabric 35 is
attached by heat-weld or a like means between the projection 31 and the
ribs 33 and also between the projection 29 and the ribs 34 in the upper
and lower halves 22a and 22b.
The distance from the center of the driving hole 28 of the lower half 22b
to the ribs 33 and 34 is somewhat longer than the radius of the flexible
magnetic disk 21 is displaced within the cassette cover 22 by the
looseness of the center core disk 23 in the driving hole 28, the
peripheral edge portion of the flexible magnetic disk 21 does not abut the
ribs 33 and 34.
In the upper and lower halves 22a and 22b of the cassette cover 22 and the
non-woven fabric 35, there are respectively formed openings 36, 37 and 38
of the same shape extending in a radial direction of the flexible magnetic
disk 21, the openings 36, 37 and 38 being overlapped in opposed relation.
And as will be described later, a magnetic head is inserted in the opening
formed in the lower half 22b through the opening formed in the lower
non-woven fabric 35, while a head pressing pad is inserted from the
opening 16 formed in the upper half 22a through the opening 18 formed in
the upper non-woven fabric 35. In FIG. 3, the reference numerals 39a, 39b,
are positioning projections for mutual engagement when assembling the
upper and lower halves 22a and 22b.
As shown in FIG. 3, there is formed a recess 40 on each of the outer
surfaces of the upper and lower halves 22a and 22b in the respective
portions where there are formed the pad insertion opening 36 and the head
insertion opening 37. In the recess 40 there is mounted a shutter 44
having a U-shaped cross-section made from aluminum, stainless steel, a
synthetic resin, or the like, so as to be slidable in a predetermined
direction. In the recess 40 of the lower half 22b, as shown in FIG. 6, a
rectilinear guide groove 42 is formed extending along a side edge portion
of the cassette cover 22, while in relation to the guide groove 42 there
is formed in the shutter 41, as shown in FIG. 8, a pawl-like projection
43, for example, in three places, formed by inwardly bending a part of the
shutter 41 by means of pressure or the like. The pawl-like projection 43
of the shutter 41 is inserted in the guide groove 42 of the lower half 22b
so that the shutter 41 is guided by the groove 22 slidably in the
direction of arrows A and B in FIG. 6. The shutter sliding mechanism is
not limited to what has just been mentioned. For example, as shown in FIG.
9, a part of the shutter 41 may be subjected to half-blanking by means of
pressing or the like to form a projection 44a which projects inwardly of
the shutter 41, and the projection 44a is slidably fitted in the guide
groove 42. Further, as shown in FIG. 10, a V-shaped projection 44b may be
formed which projects inwardly of the shutter 41. This projection 44b is
slidably fitted in the guide groove 42. In the side edge portion of the
lower half 22b where the guide groove 42 is formed, as shown in FIG. 6
there is formed a shutter mounting and demounting recess 56 in
communication with the guide groove 42, for example in three places. When
the shutter 41 is slid, for example, in the direction of arrow B in FIG. 6
to the position indicated with a dot-dash line, the recess 56 and the
pawl-like projection 43 of the shutter 41 become opposed to each other. In
this state, if a force is applied in a pulling direction of the shutter 41
from the cassette cover 22, the shutter 41 can be easily demounted or
removed from the cassette cover 22.
In each of the opposed plate portions 41a and 41b of the shutter 41 there
is formed an opening 45 having substantially the same shape as the pad and
head insertion openings 36 and 37. By sliding the shutter 41 along the
guide groove 42, the pad and head insertion openings 36 and 37 can be
opened or closed selectively. In case the shutter 41 is disposed in such a
position as indicated with a solid line in FIG. 6, the opening 45 in the
shutter 41 and the openings 36 and 37 in the cassette cover 22 become
overlapped with one another, that is the openings 36 and 37 are opened. On
the other hand, in case the shutter 41 is slid to the position shown with
a dot-dash line in FIG. 4, the openings 36 and 37 are covered and closed
with the shutter 41.
In the side portion of the cassette cover 22 where the shutter 41 is
mounted, there is formed a channel-shaped cutout portion 53 as shown in
FIG. 3 and FIG. 6. This cutout portion 53 is opened or closed along with
the above-described sliding movement of the shutter 41. That is, when the
opening 45 in the shutter 41, the openings 36 and 37 in the cassette cover
22, and the opening 38 of the fabric 35 overlap each other, the cut-out
portion 53 is opened, while when the openings 36, 37 and 38 are covered
with the shutter 41, the cutout portion 53 is also closed. In case the
cutout portion 53 is opened, as will be describ | | |
