Disk cartridge with shutter and slider, and method of connecting them

A disk cartridge has a shutter. The shutter is slidably connected to a shell body by a slider made of synthetic resin. The shutter has a plurality of pin-insertion holes on its mating surface. The slider has a plurality of connecting pins that are inserted into the pin-insertion holes of the shutter so that its mating surface mates with the mating surface of the shutter. The connecting pins are formed at distal ends thereof with heads having larger diameters than the pin insertion holes to support the shutter between the heads and the mating surface of the slider. The heads of the connecting pins are provided by plastic-deforming the distal ends of the connecting pins.

TECHNICAL FIELD 
The present invention relates to a disk cartridge in which a shutter is 
slidably mounted on a shell body through a slider so as to open and close 
an aperture provided on the shell body for receiving a head or spindle, 
and particularly to a disk cartridge in which coupling of the shutter with 
the slider is carried out simply, easily, surely, and quickly without 
using tapping screws. 
BACKGROUND ART 
There is known a disk cartridge (for example, 3.5-inch MO disk cartridge) 
as shown in FIG. 25, in which a shutter 101 is slidably mounted on a shell 
body 103 through a slider 102 to open and close an aperture 104 provided 
on the shell body 103 for receiving a magnetic head. 
The shutter 101 is formed of a generally U-shaped metal plate and with 
screw-insertion holes (not shown) at both ends of a surface mating with 
the slider 102. 
The slider 102 is made of a synthetic resin and coupled with the shutter 
101 by screws 105 and 106 inserted into the screw-insertion holes of the 
shutter 101. 
The shell body 103 is composed of an upper half 111 and a lower half 112 
and accommodates a disk-shaped recording medium 113 (hereinafter referred 
to as disk) interposed between these upper and lower halves 111 and 112. 
The conventional disk cartridge as described above has the following 
problems because of the construction in which the shutter 101 is coupled 
with the slider 102 by using the screws 105 and 108. 
(1) Using of the screws 105 and 108 causes an increase in the number of 
parts, leading to a higher manufacturing cost. 
(2) Tightening of the screws 108 and 106 for coupling the shutter 101 with 
the slider 102 causes a reduction of assembling efficiency. This is 
because the tightening must be generally performed by using a parts feeder 
which is used for bringing the screws into line and transporting them to a 
tightening device. However, the screws tend to stick on the parts feeder 
during the transportation. 
The present invention contemplates to solve the conventional problems as 
mentioned above. 
DISCLOSURE OF THE INVENTION 
The present invention aims to provide a disk cartridge comprising: a shell 
body accommodating a disk rotatably disposed therein; 
a slider disposed slidably along one end of the shell body and made of 
synthetic resin; and 
a shutter secured to the slider for opening and closing a head or spindle 
insertion aperture formed on the shell body in association with sliding 
movement of the slider; 
the shutter having a plurality of pin-insertion holes formed on its mating 
surface, the slider having a plurality of connecting pins formed on its 
mating surface which mates with the mating surface of the shutter, the 
connecting pins being inserted into the pin-insertion holes and 
plastic-deformed at distal ends thereof to be provided at the distal ends 
with heads having greater diameters than the pin-insertion holes so that 
the shutter is interposed between the heads and the mating surface of the 
slider whereby the shutter and the slider are coupled together. 
Therefore, the disk cartridge according to the present invention can 
dispense with the screws for connecting the shutter and the slider which 
are used in the conventional disk cartridge. This leads to a reduction in 
the number of parts.

BEST MODE FOR EMBODYING THE INVENTION 
The present invention will be explained with reference to FIGS. 1-24. 
FIG. 1 shows a perspective view of a disk cartridge 1 of a first embodiment 
according to the present invention. 
The disk cartridge 1 includes a disk 2 acting as a recording medium, a 
shell body (casing) 3 receiving the disk 2, a shutter 6 made of metal and 
slidably mounted on the shell body 3 through a slider 4 made of synthetic 
resin to open and close a head or spindle insertion aperture 5 formed on 
the shell body 3, a shutter spring 7 forcing the shutter 6 to be kept in 
its closed position, a write protector 8, and a shutter guide 9. 
As illustrated in FIG. 2, the shutter 6 has a first pin-insertion hole 11 
at one end of its mating surface 6a, in a shutter sliding direction 
(direction as indicated by double-headed arrow a-b), and a second 
pin-insertion hole 12 at the other end thereof. 
The slider 4 has, at its mating surface 4a mating with the mating surface 
6a of the shutter 6, a first connecting pin 13 inserted into the first 
pin-insertion hole 11, and a second connecting pin 14 inserted into the 
second pin-insertion hole 12. 
The first connecting pin 13 has at its distal end a greater-diameter head 
13a which cooperates with the mating surface 4a mating with the shutter 6 
to support the shutter 6 therebetween. 
The second connecting pin 14 has at its distal end a greater-diameter head 
14a which cooperates with the mating surface 4a mating with the shutter 6 
to support the shutter 6 therebetween. 
As illustrated in FIG. 3, the first connecting pin 13 and the second 
connecting pin 14 are of a cylindrical shape. 
The first pin-insertion hole 11 is of a circular shape having substantially 
same diameter as the first connecting pin 13. 
The first connecting pin 13 is received in the first pin-insertion hole 11 
in a tight-fitting manner. 
The first pin-insertion hole 11 acts as a reference hole for relative 
positioning of the shutter 6 and the slider 4 upon coupling the shutter 6 
with the slider 4, and the first connecting pin 13 acts as a reference pin 
therefor. 
The second pin-insertion hole 12 is of a generally circular shape elongated 
in the shutter sliding direction. 
The second connecting pin 14 is received in the second pin-insertion hole 
12 with a clearance .delta. in the shutter sliding direction. 
The clearance .delta. is provided for compensating dimensional errors 
occurring inevitably in the formation of the first and second 
pin-insertion holes 11 and 12 and the first and second connecting pins 13 
and 14, upon coupling the shutter 6 on the slider 4, so that the second 
connecting pin 14 is reliably received in the second pin-insertion hole 
12. 
Next, the disk cartridge of the first embodiment will now be explained in 
detail. 
FIG. 4 is a perspective view of the disk cartridge 1 before assembly. 
The disk 2 includes a disk-shaped recording medium 21, and a hub 22 made of 
metal and mounted to a central portion of the recording medium 21. 
The shell body 3 includes an upper half 31 and a lower half 32. 
Each of the upper and lower halves 31 and 32 is formed on its outer surface 
with a recessed portion for mounting the shutter, which forms a shutter 
sliding area 33 having the head or spindle insertion aperture 5 on one 
side 33a thereof. 
The shutter 6 is mounted in such a way as to pinch the upper and lower 
halves 31 and 32 at the shutter sliding areas 33 and 23. 
The shutter 6 has a pair of aperture-opening/closing sections 41 and 42 
overlapped in the shutter sliding areas 33 and 23 of the upper and lower 
halves 31 and 32, and a connecting section 43 connecting one end of the 
aperture opening/closing section 41 with one end of the aperture 
opening/closing section 42. 
As illustrated in enlarged scale in FIG. 5, the connecting section 43 is 
formed at one end portion thereof in the shutter sliding direction 
(longitudinal direction) with a first recessed portion 44, and at the 
other end portion thereof in the same direction with a second recessed 
portion 45. 
The first recessed portion 44 has the first pin-insertion hole 11 on its 
bottom and the second recessed portion 45 has the second pin-insertion 
hole 12 on its bottom. 
The first and second recessed portions 44 and 45 are formed upon shaping 
the opposite end portions of the connecting section 43 by drawing. 
The first recessed portion 44 is of a cylindrical shape. 
The first pin-insertion hole 11 is provided at the center of the bottom of 
the first recessed portion 44 in the form of a circle having a smaller 
diameter than a diameter of the first recessed portion 44. 
The second recessed portion 45 is of an ellipsoid shape elongated in the 
shutter sliding direction. 
The second pin-insertion hole 12 is provided at the center of the bottom of 
the second recessed portion 45 in the form of an ellipsoid elongated in 
the shutter sliding direction, which shape is similar to the shape of the 
second recessed portion 45. 
The slider 4 is now explained in detail. 
The slider 4 has an elongated rectangular parallelepiped-shaped body 
portion 51, a first guide portion 52 provided at one end thereof in a 
longitudinal direction of the body portion 51 (the shutter sliding 
direction), and a second guide portion 53 at the other end thereof in the 
same direction. 
The body portion 51 has a thickness T which is smaller than a clearance G 
(see FIG. 1) between the upper and lower halves 31 and 32 of the shell 
body 3, and a length substantially same as a width W of the shutter 
sliding area 5 of the shell body 3. 
The mating surface 4a of the body portion 51 which mates with the shutter 6 
has at one end portion thereof a first concaved portion 54 engaged with 
the first recessed portion 44 of the shutter 6, and at the other end 
portion thereof a second concaved portion 55 engaged with the second 
recessed portion 45 of the shutter 6. 
A first straight pin 56 extends uprightly from the center of a bottom of 
the first concaved portion 54, acting as the first connecting pin 13 after 
the head 13a is formed thereon. 
A second straight pin 57 extends uprightly from the center of a bottom of 
the second concaved portion 55, acting as the second connecting pin 14 
after the head 14a is formed thereon. 
The first straight pin 56 and the second straight pin 57 are shaped into a 
cylindrical column. 
In addition, the first straight pin 56 and the second straight pin 57 have 
distal ends of a conical shape. 
The first straight pin 56 is so designed as to have a predetermined height 
(length). 
The second straight pin 57 is so designed as to be slightly higher (longer) 
than the first straight pin 56. 
The first straight pin 56 and the second straight pin 57 are inserted into 
the first pin-insertion hole 11 and the second pin-insertion hole 12, 
respectively. As illustrated in FIG. 6, the first straight pin 56 is 
engaged with the first pin-insertion hole 11 in tight-fitting relation to 
an inner circumferential surface of the first pin-insertion hole 11. 
On the other hand, the second straight pin 57 is engaged in a generally 
central portion of the second pin-insertion hole 12 with the predetermined 
clearance .delta. formed back and forth in the shutter sliding direction. 
Owing to the fitting engagement of the first straight pin 56 with the first 
pin-insertion hole 11, the relative positioning of the shutter 6 and the 
slider 4 is determined. Simultaneously, the provision of the clearance 
.delta. between the second straight pin 57 and the second pin-insertion 
hole 12 serves for compensating dimensional errors occurring inevitably 
when the first and second straight pins 56 and 57 and the pin-insertion 
holes 11 and 12 are formed. Then, subsequent to inserting the first 
straight pin 56 and the second straight pin 57 into the first 
pin-insertion hole 11 and the second pin-insertion hole 12, respectively, 
as described above, the heads 13a and 14a are formed at the distal ends of 
the first and second straight pins 56 and 57, respectively. 
The formation of the heads 13a and 14a is performed, as shown in FIG. 7, by 
using an ultrasonic welding machine in such a manner that horns 71 of the 
ultrasonic welding machine are contacted with the distal ends of the first 
and second straight pins 56 and 57 to apply vibrations thereto. 
The horns 71 have on lower surfaces thereof arcuate head-forming faces 71a 
which are so designed as to have same configuration and size as the heads 
13a and 14a. 
The horn 71 moves downward until the arcuate head-forming face 71a contacts 
the distal end of the first straight pin 56 or second straight pin 57. 
When the horn 71 is caused to vibrate, first, the distal end of the first 
straight pin 56 or second straight pin 57 is heated at its portion 
contacting the horn and plastic-deformed to be shaped into a curved 
surface along the arcuate head-forming face 71a. As a result, the first 
straight pin 56 or second straight pin 57 is provided with the head 13a or 
14a as shown in FIG. 2 at the distal end thereof, acting as the first 
connecting pin 13 with the head 13a or the second connecting pin 14 with 
the head 14a. 
The head 13a or 14a is received in the first or second recessed portion 44 
or 45 to prevent it from projecting from an outer surface of the 
connecting section 43 of the shutter 6. 
As illustrated in FIG. 8, when coupled with the shutter 6 as explained 
above, the slider 4 is interposed between the upper and lower halves 31 
and 32 so that the first and second guide portions 52 and 53 are engaged 
with guide grooves 31a and 32a which are formed on inner surfaces of the 
upper and lower halves 31 and 32, respectively. Thus, the shutter 6 is 
slidably mounted on the shell body 3. 
The disk cartridge of the first embodiment has a construction as described 
above. 
Accordingly, the slider 4 and the shutter 6 can be coupled with each other 
by means of the first and second connecting pins 13 and 14 formed 
integrally with the slider 4 made of synthetic resin, without using 
tapping screws. 
In addition, there are provided the fitting engagement of the first 
connecting pin 13 with the first pin-insertion hole 11, and the loose 
engagement of the second connecting pin 14 with the second pin-insertion 
hole 12 with play therebetween. 
Accordingly, the first pin-insertion hole 11 has a function as the 
reference hole for positioning and the first connecting pin 13 has a 
function as the reference pin for positioning. 
Further, the coupling of the slider 4 and the shutter 6 is readily 
performed by providing the clearance .delta. between the inner 
circumferential surface of the second pin-insertion hole 12 and an outer 
circumferential surface of the second connecting pin 14 received therein 
for compensating dimensional errors occurring inevitably upon the 
formation of the first and second connecting pins 13 and 14 and the first 
and second pin-insertion holes 11 and 12. 
FIGS. 9 and 10 show a second embodiment of the present invention. 
In this embodiment, the first pin-insertion hole 11 acting as the reference 
hole for positioning is of an elliptic shape elongated in the shutter 
sliding direction. 
The first straight pin 56 engaged with the first pin-insertion hole 11 is 
designed corresponding to the configuration of the first pin-insertion 
hole 11 to have a thickness in the shutter sliding direction which is 
greater than a thickness in a direction normal to the shutter sliding 
direction. 
The reason why the first straight pin 56 has a lesser thickness in the 
normal direction than the thickness in the shutter sliding direction is 
that the disk cartridge 1 actually has no room for accommodating the first 
straight pin 56 having the increased thickness in the normal direction 
because the thickness of the disk cartridge 1 is strictly standardized. 
The first straight pin 56 is engaged with the first pin-insertion hole 11 
in a tight-fitting manner. 
Then, the first straight pin 56 is formed at its distal end with a head by 
using an ultrasonic welding machine and provided as the first connecting 
pin 13. 
Other structural parts are substantially same as those of the first 
embodiment and therefore repeated explanations thereof are omitted. 
Since the disk cartridge of the second embodiment is so arranged that the 
first connecting pin 13 engaged with the first pin-insertion hole 11 
acting as the reference hole for positioning, has the greater thickness in 
the shutter sliding direction and the lesser thickness in the direction 
normal to the shutter sliding direction, the first connecting pin 13 has 
an increased mechanical strength in the shutter sliding direction. 
Therefore, the first connecting pin 13 is prevented from being damaged 
even in a case where an excessive stress is applied thereto in the shutter 
sliding direction. 
FIGS. 11-13 show a third embodiment of the present invention. 
In this embodiment, the shutter 6 is so designed as to close the head or 
spindle insertion aperture 5 at a position near to the one side 33a of 
each shutter sliding area 33 of the shell body 4 in the shutter sliding 
direction. 
The second connecting pin 14 which is placed at a farthest position away 
from the one side 33a of the shutter sliding area 33, is of a generally 
ellipsoidal shape having a thickness in the shutter sliding direction 
which is greater than a thickness in the direction normal to the shutter 
sliding direction. 
As illustrated in FIG. 12, the second pin-insertion hole 12 is of a 
generally ellipsoidal shape elongated in the shutter sliding direction. 
The second straight pin 57 acting as the second connecting pin 14 is of a 
generally ellipsoidal shape having a thickness in the shutter sliding 
direction which is greater than a thickness in the direction normal to the 
shutter sliding direction, similar to the second connecting pin 14. 
The second straight pin 57 is loosely engaged with the second pin-insertion 
hole 12 with a predetermined clearance .delta. back and forth in the 
shutter sliding direction. 
Further, the second straight pin 57 is formed at its distal end with a head 
by using an ultrasonic welding machine and provided as the second 
connecting pin 13. 
Other structural parts are substantially same as those of the first 
embodiment and therefore repeated explanations thereof are omitted. 
In the third embodiment, the second connecting pin 14 located at the 
farthest position away from the one side 33a of the shutter sliding area 
33 has the greater thickness in the shutter sliding direction and the 
lesser thickness in the direction normal to the shutter sliding direction. 
This provides an increased mechanical strength in the shutter sliding 
direction. The increased mechanical strength in the shutter sliding 
direction is required for achieving the following purpose. 
If the shutter 6 falls on the ground at a predetermined drop angle relative 
to the ground g as illustrated in FIG. 14, then the shutter 6 is exposed 
to an impact thereupon. 
In this case, a force fa applied to the first connecting pin 13 and a force 
fb applied to the second connecting pin 14 are expressed by the following 
formulas: 
EQU fa.multidot.cos.theta.a+fb.multidot.cos.theta.b=Wcos.theta. 
EQU fa.multidot.sin.theta.a+W.multidot.sin.theta.=fb.multidot.sin.theta.b 
where, 
G denotes the center of gravity, 
W denotes the weight of the shutter, 
.theta.a denotes an angle of the line between the first connecting pin 13 
and G relative to vertical, and 
.theta.b denotes an angle of the line between the second connecting pin 14 
and G relative to vertical. 
Namely, fa and fb are unequal and functions of the drop angle .theta.. 
As a result, fb/fa is approximately 2.5, if the drop angle 
.theta.=45.degree.. Accordingly, in the case of falling as mentioned 
above, an impact force applied to the second connecting pin 14 is 
approximately two and a half times greater than an impact force applied to 
the first connecting pin 13. 
This is the reason the second connecting pin 14 is of a generally 
ellipsoidal shape to have a sectional area which is larger by 
approximately two and a half times than the first connecting pin 13, 
whereby the second connecting pin 14 is as resistant to the impact force 
applied upon falling, as the first connecting pin 13. 
As illustrated in FIG. 15, in the case reverse to the aforementioned case, 
where the disk cartridge 1 falls at the drop angle .theta.=44.degree. in 
such a manner that its corner located on an opposite side of the shutter 6 
to the side thereof as indicated in the aforementioned case, is hit on the 
ground, the impact force applied to the first connecting pin 13 is greater 
than the impact force applied to the second connecting pin 14. 
However, since the shutter 6 is contacted with the one side 33a of the 
shutter sliding area 33 of the shell body 3 to be supported on the one 
side 33a, the impact force applied to the first connecting pin 13 is 
reduced whereby the first connecting pin 13 is protected from the impact 
upon falling. 
FIGS. 16-22 show a fourth embodiment of the present invention. 
This embodiment is a combination of the second embodiment and the third 
embodiment, in which both the first connecting pin 13 and the second 
connecting pin 14 are of a generally ellipsoidal shape having an increased 
thickness in the shutter sliding direction. 
The first pin-insertion hole 11 is of a generally ellipsoidal shape 
elongated in the shutter sliding direction. 
As illustrated in FIG. 16, the connecting section 43 of the shutter 6 is 
formed with a first recessed portion 44 at one end portion thereof in the 
shutter sliding direction (longitudinal direction), and with a second 
recessed portion 45 at the other end portion thereof in the same 
direction. 
The first recessed portion 44 has the first pin-insertion hole 11 on its 
bottom and the second recessed portion 45 has the second pin-insertion 
hole 12 on its bottom. 
The first and second recessed portions 44 and 45 are formed upon shaping 
the opposite end portions of the connecting section 43 by drawing. 
The first recessed portion 44 is of a generally ellipsoidal shape which is 
elongated in the shutter sliding direction so as to have a length L1 and a 
width D1. 
The first pin-insertion hole 11 is provided at the center of the bottom of 
the first recessed portion 44 and has a generally ellipsoidal shape which 
is elongated in the shutter sliding direction so as to have a length L2 
and a width D2. 
The second recessed portion 45 is of a generally ellipsoidal shape which is 
elongated in the shutter sliding direction so as to have a longer length 
L3 than the length L1 of the first recessed portion 44 and a width D3 
equal to the width D1 of the first recessed portion 44. 
The second pin-insertion hole 12 is provided at the center of the bottom of 
the second recessed portion 45 and has a generally ellipsoidal shape which 
is elongated in the shutter sliding direction so as to have a longer 
length L4 than the length L2 of the first pin-insertion hole 11 and a 
width D4 equal to the width D2 of the first pin-insertion hole 11. 
The mating surface 4a of the body portion 51 of the slider 4, which mates 
with the shutter 6, has at one end portion thereof a first concaved 
portion 54 engaged with the first recessed portion 44 of the shutter 6, 
and at the other end portion thereof a second concaved portion 55 engaged 
with the second recessed portion 45 of the shutter 6. 
A first straight pin 56 extends uprightly from the center of a bottom of 
the first concaved portion 54 and acts as the first connecting pin 13 
after the head 13a is formed thereon. 
A second straight pin 57 extends uprightly from the center of a bottom of 
the second concaved portion 55 and acts as the second connecting pin 14 
after the head 14a is formed thereon. 
The first straight pin 56 and the second straight pin 57 have a generally 
ellipsoidal shape as viewed from the distal end side (in a direction as 
indicated by arrow A), which is elongated in the shutter sliding direction 
as similar to the first pin-insertion hole 11. 
The first straight pin 56 and the second straight pin 57 have 
mountain-shaped tip ends having edges 58 extending in the shutter sliding 
direction. The first straight pin 56 has a predetermined height (length). 
The second straight pin 57 is so designed as to be higher (longer) than the 
first straight pin 56. 
When the first straight pin 56 and the second straight pin 57 are inserted 
into the first pin-insertion hole 11 and the second pin-insertion hole 12, 
respectively, the first straight pin 56 is engaged with the first 
pin-insertion hole 11 in tight-fitting relation to an inner 
circumferential surface of the first pin-insertion hole 11, as shown in 
FIG. 17. 
On the other hand, the second straight pin 57 is received at the center of 
the second pin-insertion hole 12 with a predetermined clearance .delta. 
back and forth in the shutter sliding direction. 
Owing to the fitting engagement of the first straight pin 56 with the first 
pin-insertion hole 11 as described above, the relative positioning of the 
shutter 6 and the slider 4 is performed. Simultaneously, the provision of 
the clearance .delta. between the second straight pin 57 and the second 
pin-insertion hole 12 serves for compensating dimensional errors occurring 
inevitably upon the formation of the first and second straight pins 56 and 
57 and the pin-insertion holes 11 and 12. 
Then, subsequent to inserting the first straight pin 56 and the second 
straight pin 57 into the first pin-insertion hole 11 and the second 
pin-insertion hole 12, respectively, as described above, the heads 13a and 
14a are formed at the distal ends of the first and second straight pins 56 
and 57, respectively. 
As shown in FIGS. 17 and 18, the formation of the heads 13a and 14a is 
performed by using an ultrasonic welding machine in such a manner that 
first and second horns 71 and 72 of the ultrasonic welding machine are 
contacted with the distal ends of the first and second straight pins 56 
and 57 to apply vibrations thereto. 
The first horn 71 is provided for forming the head 13a at the distal end of 
the first straight pin 56 and has its lower surface acting as an arcuate 
head-forming face 71a which is so designed as to have same configuration 
and size as the head 13a. 
First, the first horn 71 moves downward until the arcuate head-forming face 
71a contacts the edge 58 of the distal end of the first straight pin 56. 
Then, when the first horn 71 is caused to vibrate, the edge 58 of the first 
straight pin 56 is heated and plastic-deformed to be shaped into a curved 
surface along the arcuate head-forming face 71a. As a result, as 
illustrated in FIGS. 19 and 20, the head 13a is provided at the distal end 
of the first straight pin 56 in the first concaved portion 54 so that the 
first straight pin 56 forms the first connecting pin 13 having the head 
13a at the distal end. 
The second horn 72 is provided for forming the head 14a at the distal end 
of the second straight pin 57 and has its lower surface acting as an 
arcuate head-forming face 72a which is so designed as to have same 
configuration and size as the head 14a. First, the second horn 72 moves 
downward until the arcuate head-forming face 72a contacts the edge 58 of 
the distal end of the second straight pin 57. Then, when the second horn 
72 is caused to vibrate, the edge 58 of the second straight pin 57 is 
heated and plastic-deformed to be shaped into a curved surface along the 
arcuate head-forming face 72a. As a result, as illustrated in FIGS. 19 and 
20, the head 14a is provided at the distal end of the second straight pin 
57 in the second concaved portion 55 so that the second straight pin 57 
forms the second connecting pin 14 having the head 14a at the distal end. 
When the head 14a is formed by applying vibration to the distal end of the 
second straight pin 57 through the second horn 72, a shearing flash 73 
(projection) as shown in FIG. 21, is produced in the clearance .delta. 
formed at a portion of the slider 4 at which the second straight pin 57 is 
uprightly provided. 
Although it is likely that the shearing flash 73 projecting outwardly from 
the clearance .delta. gives a poor appearance of the shutter 6, the head 
14a of the second connecting pin 14 is contacted at a lower face 14b 
extending along its circumferential edge with an upper face 12a extending 
along a full circumference of the second pin-insertion hole 12 of the 
shutter 4 so that the shearing flash 73 is received in the second 
pin-insertion hole 12 and therefore prevented from exposure to the 
outside. 
The disk cartridge of the fourth embodiment has the construction as 
described above in which the first connecting pin 13 and the second 
connecting pin 14 have the increased thickness in the shutter sliding 
direction to thereby provide an enhanced mechanical strength in that 
direction. 
Accordingly, the first connecting pin 13 can be avoided from being broken 
even if a strong force in a shearing direction is applied to the first 
connecting pin 13 by pressing the slider 4 when the shutter 6 is placed in 
a position as illustrated in FIG. 22, namely in the case where the shutter 
6 opens the head or spindle insertion aperture 5 and is prevented from its 
further sliding movement from the position. 
Similarly, even in the event that a strong force is applied to the second 
connecting pin 14 in the axial direction upon falling of the disk 
cartridge, the second connecting pin 14 can be prevented from being 
broken. 
In this embodiment, since the head 14a of the second straight pin 57 is 
larger than the head 13a of the first straight pin 56, a great amount of 
synthetic resin is required for manufacturing the head 14a. This is the 
reason why the second straight pin 57 is designed to be higher than the 
first straight pin 56. 
FIG. 23 shows a fifth embodiment of the present invention. 
This embodiment provides an arrangement having improved coupling strength 
between the slider 4 and the shutter 6 by providing the slider 4 with 
first, second, and third straight pins 56, 57, and 59, providing the 
shutter 6 with first, second, and third recessed portions 44, 45 and 60, 
and forming first, second, and third pin-insertion holes 11, 12, and 61 on 
bottoms of these first, second, and third recessed portions 44, 45 and 60. 
The second and third straight pins 57 and 59 are so designed as to be 
slightly higher (longer) than the first straight pin 56. 
The first pin-insertion hole 11 is of a circular shape and the second and 
third pin-insertion holes 12 and 61 are of an elongated circular shape. 
The first, second, and third straight pins 56, 57, and 59 are inserted into 
the first, second, and third pin-insertion holes 11, 12, and 61 and the 
first, second, and third recessed portions 44, 45, and 60, respectively. 
Then, the first, second, and third straight pins 56, 57, and 59 are 
plastic-deformed in the first, second, and third recessed portions 44, 45, 
and 60 by using an ultrasonic welding machine to be formed at their distal 
ends with larger-diameter heads for firmly coupling the slider 4 and the 
shutter 6. Other structural parts are similar to the first embodiment, and 
therefore repeated explanations thereof are omitted. 
FIG. 24 shows a sixth embodiment of the present invention. 
This embodiment provides an arrangement in which a firm coupling of the 
slider 4 and the shutter 6 is performed by providing first and second 
straight pins 56 and 57 and first and second positioning pins 62 and 63 on 
the slider 4, inserting the first and second positioning pins 62 and 63 
into positioning-pin-insertion holes 64 and 65 formed on the shutter 6 to 
perform the positioning of the slider 4 relative to the shutter 6, and 
plastic-deforming the distal ends of the first and second straight pins 56 
and 57 by using an ultrasonic welding machine to provide the heads. 
In this embodiment, since there is provided the engagement of the 
positioning pins 62 and 63 with the positioning-pin-insertion holes 64 and 
65, it is not required to use either one of the first and second straight 
pins 56 and 57 for positioning as explained in the first through the fifth 
embodiments. 
In the above embodiments, although the first connecting pin 13 or the 
second connecting pin 14 are of a generally ellipsoidal shape, their 
configuration is not limited to the ellipsoidal shape but may be an 
elongated rectangular shape or other shapes. It is essential only that the 
configuration is approximately of an ellipsoidal shape and so designed as 
to provide an increased mechanical strength in a sliding direction of the 
shutter. 
In addition, the number of the connecting pins and the number of the 
pin-insertion holes are not limited to two and may be more than three.