Protective structure for jacket for rotatable magnetic recording media

This invention provides an inexpensive structure for a protecting jacket for rotatable magnetic recording media which has a dimension sufficient to cover openings on the jacket and is provided as a sheet adhered to the jacket to cover said openings and prevent entry of dust.

BACKGROUND 
This invention relates to a jacket for rotatable magnetic recording medium 
and more particularly to a protective structure for the jacket which can 
prevent dust from entering the jacket. 
Rotatable magnetic sheets (generally known as floppy discs) are widely used 
as media for magnetic recording and reproducing in recent years. These 
rotatable magnetic sheets are usually sheathed in a package (referred to 
as a jacket hereinafter) provided with internal liners made of non-woven 
fabric. The jacket has an opening at the center thereof for rotating the 
magnetic sheet, an opening for contacting the rotatable magnetic sheet 
with a magnetic head and an opening for displaying sectors. Dust in the 
air tends to enter the jacket through these openings to contaminate the 
surface of the magnetic sheet, and cause errors. 
Such a jacket is usually placed in an envelope for protecting it mainly 
from such dust. However, as such an envelope covers only two thirds or 
three fourths of the surface of the jacket and is not closely attached to 
said opening of the jacket, dust in the air cannot be fully prevented from 
entering the jacket into the envelope. 
Moreover, the jacket is taken out from the envelope when a user wishes to 
use the rotatable magnetic sheet therein, and the user tends to throw away 
the envelope. The openings of a jacket are often exposed to the air when 
such sheet is stored for a long time. 
The material of such an envelope was mainly made of natural paper in the 
prior art, but recently they are often made of synthetic paper such as of 
polyethylene (e.g. TYVEK Manufactured by DuPont). 
When we consider cost-wise a product comprising a rotatable magnetic sheet, 
a jacket and a protective envelope, the cost of the envelope is by no 
means negligible and it is not quite effective in preventing dust. 
BRIEF SUMMARY OF THE INVENTION 
This invention provides a protective structure for the jackets of rotatable 
recording medium which can almost completely prevent dust in the air from 
entering the jackets and yet is low in cost. 
The protective structure for rotatable recording medium jackets according 
to this invention is characterized in that a protective sheet which is 
applied with adhesive on one surface thereof covers at least an opening of 
the jacket for driving the magnetic recording medium therein and an 
opening for contacting the magnetic recording medium with a magnetic head 
out of the aforementioned various openings on the jackets. As these 
openings are bored on both sides of a jacket, it is desirable for the 
structure to cover them from both sides. Two notches are provided near the 
opening for contacting the medium with the magnetic head. They are 
preferably covered with the protective structure together with the 
opening. 
The protective sheet may be in any form so long as it can effectively cover 
the openings of the jacket. 
The openings of a jacket are covered with such a protective sheet to 
prevent dusts from entering them. When recording or reproducing is 
desired, such protective sheet should be peeled off.

DETAILED DESCRIPTION OF THE INVENTION 
The invention is now explained referring to embodiments shown in the 
attached drawings. This invention, however, is by no means limited to 
these illustrated embodiments. 
FIG. 1 is a perspective view showing an embodiment of this invention and 
more particularly showing the state of the protective sheet 1 when it is 
folded before being adhered to a jacket 2. FIG. 2 is a plan view of the 
protective sheet 1 when pasted on a jacket 2. The protective sheet 1 
covers an opening 3 for driving a rotatable magnetic recording medium, an 
opening 4 for contacting the rotatable magnetic sheet with a magnetic head 
and an opening 5 for displaying sectors out of various openings on the 
jacket. FIG. 3 is a developed view of the protective sheet. The protective 
sheet 1 is substantially a rectangle having semi-circles respectively on 
both short sides or ends thereof. The rounded portions are for covering 
the opening 3 at the center of the jacket 2 for driving the rotatable 
magnetic sheet. A folding line 6 exists at the center of the protective 
sheet 1. The sheet 1 is folded on the line 6 symmetrically to cover the 
opening on the jacket from both sides in a manner shown in FIG. 1, and it 
also covers notches 7. The protective sheet 1 may be made of synthetic 
paper and is applied with adhesive on the surface which contacts with the 
jacket for snug attachment. 
If adhesive is applied only on the peripheral portion 8 of the sheet 1 as 
shown by a broken line in FIG. 3, the rotatable magnetic sheet which is 
exposed through the openings on the jacket 2 will be free of such 
adhesive. 
FIGS. 4 and 5 show another embodiment of this invention. The protective 
sheet according to this embodiment is shaped like a dumbbell or two 
circles connected by a rectangle. The circular portions are for covering 
the opening 3 for driving the rotatable magnetic sheet and the opening 5 
for displaying sectors while the rectangular portion together with the 
circular portions are to cover the opening 4 for contacting the rotatable 
magnetic sheet with the magnetic head. This protective sheet, however, 
does not cover notches 7 of the jacket 2. The protective sheet may be made 
of natural paper and the surfaces contacting the jacket 2 are applied with 
adhesive. 
FIGS. 6 and 7 show the third embodiment of this invention. This protective 
sheet according to this embodiment is formed in a rectangle which is to be 
folded symmetrically at the center folding line 6 to cover the opening 3 
for driving the magnetic sheet, the opening 4 for contacting the sheet 
with the magnetic head and the opening 5 for displaying sectors from both 
sides of the jacket. The protective sheet 1 may be made of a thin plate of 
polyvinyl chloride mixed with carbon black which is an antistatic agent. 
Magnetic recording media can be effectively protected by the antistatic 
agent from faults which might otherwise be caused electrostatically. 
FIGS. 8 and 9 show the fourth embodiment of this invention. This protective 
sheet 1 is formed in two sectors which is folds symmetrically at the 
folding line 6 from which it diverges to rounded ends to cover the opening 
3 for driving the rotatable magnetic sheet, the opening 4 for contacting 
the magnetic sheet with the magnetic head and the opening 5 for displaying 
sectors. This protective sheet does not cover openings of notches 7 on the 
jacket 2. 
This invention provides a protective structure which covers a jacket with a 
protective sheet. When a rotatable magnetic recording medium in the jacket 
is used for recording or reproducing, the protective sheet is peeled off 
from the jacket and then the jacket is inserted in a magnetic disc unit or 
the like. 
When such a rotatable magnetic recording medium must be stored for a long 
time after use, the protective sheet according to this invention, if 
adhered to the jacket, can effectively protect the medium from dust in the 
air. This protective sheet has a strip of releasing paper on the surface 
applied with adhesive. The releasing paper may be peeled off and stuck on 
a jacket while the jacket is being stored. 
While various materials are mentioned above relative to the different 
embodiments, the invention is not limited to a particular material for a 
particular configuration of the protective sheet. In fact, the material of 
a protective sheet according to this invention may be paper (natural or 
synthetic) or resins, and possibly textile, metal, etc. Protective sheets 
are punched out from thin metal plates or cut out of textile. But when 
ease of use, effect in prevention of dust, weight and costs are 
comprehensively considered, paper or resin is preferable as the material 
of protective sheets. 
Antistatic agents or various pigments may, if possible, be mixed in the 
material for protective sheets. Antistatic agents can prevent faults 
otherwise caused by electrostatics while pigments can make sheets colorful 
for easy identification as well as better classification. 
The invention can almost completely prevent dust in the air from entering a 
jacket containing a rotatable magnetic recording medium with an 
inexpensive protective sheet. The protective sheet of this invention can 
serve for convenience of users as it can present dust from entering the 
jacket by a simple structure when users wish to keep recording media for a 
long time.