Information recording medium with light-emitting area, storage case with light-emitting area for information recording medium, and sheet with light-emitting area for information recording medium

An information recording medium, a storage case for storing an information recording medium, or a sheet for use with an information recording medium, has a light-emitting area coated with a phosphorescent paint, and a luminous paint area coated with a luminous paint for emitting exciting light to stimulate the light-emitting area to emit light, the luminous paint area being disposed adjacent to or on the light-emitting area.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an information recording medium, a storage 
case for an information recording medium, and a sheet for an information 
recording medium, all of which have a light-emitting area and a coated 
area of luminous paint for emitting exciting light to stimulate the 
light-emitting area to emit light. 
2. Description of the Related Art 
Information recording mediums including audio compact cassettes, compact 
discs, etc. are being widely used at present. 
These information recording mediums find use at night and in dark rooms as 
well as in daylight and bright conditions. Therefore, it has been desired 
to increase the visibility of characters, symbols, and other indicia on 
information recording mediums, storage cases thereof, and sheets thereon. 
It often happens for car drivers to handle information recording mediums 
for playback on car audio devices while driving cars. For safety reasons, 
it is of highly critical concern to increase the visibility of characters, 
symbols, and other indicia on information recording mediums, storage cases 
thereof, and sheets thereon that are used in cars. 
It has heretofore been proposed to coat areas which bear characters, 
symbols, and other indicia on information recording mediums, storage cases 
thereof, and sheets thereon, with a layer of paint that emits light by 
itself upon being stimulated, i.e., a layer of luminous paint, for thereby 
increasing the visibility of those characters, symbols, and other indicia. 
For example, it has been practiced to print labels of audio tape cassettes 
with luminous paint, apply seals coated with luminous paint to labels of 
audio tape cassettes, and coat a layer of luminous paint on an unrecorded 
area of information recording mediums. 
Efforts have been made to develop luminous paints capable of emitting light 
for a long period of time. Since these luminous paints are highly 
expensive to manufacture, it will be highly costly to coat those areas of 
audio tape cassette label which bear characters, symbols, and other 
indicia with an amount of luminous paint that is sufficient to directly 
illuminate those areas with light emitted thereby. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an information 
recording medium, a storage case for an information recording medium, and 
a sheet for an information recording medium, which bear characters, 
symbols, and other indicia that can be seen with good visibility with a 
minimum amount of luminous paint used. 
According to an aspect of the present invention, there is provided an 
information recording medium comprising a light-emitting area coated with 
a phosphorescent paint, and a luminous paint area coated with a luminous 
paint for emitting exciting light to stimulate the light-emitting area to 
emit light, the luminous paint area being disposed adjacent to or on the 
light-emitting area. 
According to another aspect of the present invention, there is provided a 
storage case for storing an information recording medium, comprising a 
light-emitting area coated with a phosphorescent paint, and a luminous 
paint area coated with a luminous paint for emitting exciting light to 
stimulate the light-emitting area to emit light, the luminous paint area 
being disposed adjacent to or on the light-emitting area. 
According to still another aspect of the present invention, there is 
provided a sheet for use with an information recording medium, comprising 
a light-emitting area coated with a phosphorescent paint, and a luminous 
paint area coated with a luminous paint for emitting exciting light to 
stimulate the light-emitting area to emit light, the luminous paint area 
being disposed adjacent to or on the light-emitting area. 
The information recording medium, the storage casing, or the sheet may 
further comprise a writable layer disposed on the light-emitting area. 
The light-emitting area, coated with the phosphorescent paint that is 
relatively inexpensive, is combined with the luminous paint area coated 
with the luminous paint which will emit exciting light to stimulate the 
light-emitting area to emit light. Therefore, characters, symbols, and 
other indicia marked on the information recording medium, the storage 
casing, or the sheet can be seen with good visibility with the 
light-emitting area that is coated with the relatively inexpensive 
phosphorescent paint which can be stimulated by the exciting light from 
the luminous paint area. The amount of relatively expensive luminous paint 
used in the luminous paint area can thus be small enough to lower the cost 
of the information recording medium, the storage casing, or the sheet. 
If the light-emitting layer is coated with phosphorescent paints capable of 
emitting lights of three primaries, then the emitted lights of three 
primaries may be separated to produce full colors, gradations, or 
intermediate colors, thus enabling the light-emitting layer to have an 
aesthetically pleasing appearance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Like or corresponding parts are denoted by like or corresponding reference 
characters and representations throughout views. 
A sheet for an information recording medium according to certain 
embodiments of the present invention can be applied to an inner or outer 
surface of a case for an elongate recording medium such as a magnetic 
tape, or a cassette for a magnetic tape, or can be inserted into a 
magnetic tape. 
As shown in FIGS. 1 and 2, a sheet 10 for an information recording medium 
comprises a sheet base 3, a luminous paint layer 1 disposed on the sheet 
base 3, and a light-emitting layer 2 disposed on the sheet base 3. 
The light-emitting layer 2 comprises a coated layer of phosphorescent 
paint, and the luminous paint layer 1 comprises a coated layer of luminous 
paint for emitting exciting light to stimulate the phosphorescent paint of 
the light-emitting layer 2. The luminous paint layer 1 and the 
light-emitting layer 2 are positioned adjacent to each other. 
The sheet base 3 is made of a sheet of paper, synthetic resin, or the like 
on which information can be written, and should preferably be white so as 
to provide high reflectance with respect to light. 
Examples of the coated phosphorescent paint of the light-emitting layer 2 
are shown in the following Table, which sets forth their names, chemical 
compositions, peak wavelengths (nm) of light-emission spectrums, and 
colors of emitted colors. 
TABLE 
______________________________________ 
Chemical Peak wave- 
Color of emit- 
Paint name 
composition length (nm) 
ted light 
______________________________________ 
Blue-base 
BaMg.sub.2 Al.sub.16 O.sub.27 :Eu.sup.2+ 
452 Blue 
paint 
Green-base 
BaMg.sub.2 Al.sub.16 O.sub.27 :Eu.sup.2+, Mn.sup.2+ 
450, 515 Blue green 
paint 
Red-base 
Y.sub.2 O.sub.2 S:EU.sup.3+ 
611 Reddish orange 
paint 
______________________________________ 
Examples of the luminous paint which emits exciting light to stimulate the 
phosphorescent paints in the above Table to emit light are Sr.sub.4 
Al.sub.14 O.sub.25 :Eu, Dy, and SrAl.sub.2 O.sub.4 :Eu, Dy. 
These luminous paints have an ability to store light and emit the stored 
light for an afterglow time of 200 minutes or longer. 
The luminous paint may be coated to a relatively large thickness by a silk 
screen printing process, thereby to produce the luminous paint layer 1. 
The luminous paint layer 1 should preferably have a thickness of about 0.1 
mm. 
The particles contained in the phosphorescent paint of the light-emitting 
layer 2 have a diameter of several .mu.m. Therefore, the light-emitting 
layer 2 may be formed by a silk screen printing process, a pad printing 
process, or a gravure printing process. The light-emitting layer 2 has a 
thickness of about several tens .mu.m. 
A writable layer on which information such as characters, symbols, or other 
indicia can be written may be disposed on the light-emitting layer 2. The 
writable layer may be formed by printing a paint containing calcium 
carbonate or protein powder after the phosphorescent paint has been 
printed as the light-emitting layer 2, or coating a thin resin film with a 
mat surface on the phosphorescent paint printed as the light-emitting 
layer 2. 
The principles of emission of light from the light-emitting layer 2 will be 
described below. 
FIG. 3 shows in fragmentary cross section the luminous paint layer 1 and 
the light-emitting layer 2 of the sheet shown in FIG. 2. In FIG. 3, a 
writable layer 4 on which information such as characters, symbols, or 
other indicia can be written is disposed on the light-emitting layer 2, 
and characters, symbols, or other indicia 6 are written on the writable 
layer 4. 
The luminous paint of the luminous paint layer 1 and the phosphorescent 
paint of the light-emitting layer 2 are selected such that the spectrum of 
exciting light emitted by the luminous paint and the spectrum of excited 
light emitted by the phosphorescent paint have an overlapping wavelength 
region. When stored light is emitted from the luminous paint layer 1, the 
emitted light is applied as exciting light to stimulate the light-emitting 
layer 2 to emit light. The light emitted from the light-emitting layer 2 
allows the characters, symbols, or other indicia 6 on the layer 4 to be 
visible to the human eye even at night or in a dark room. 
Since the light to illuminate those characters, symbols, or other indicia 6 
mainly comes from the light-emitting layer 2 which is made of a relatively 
inexpensive phosphorescent paint, the amount of luminous paint which is 
relatively expensive may be reduced. Accordingly, the cost of the sheet 10 
is relatively low. 
The optic nerve of the human eye exhibits different spectral luminous 
efficiencies depending on the wavelength of light, and senses yellowish 
green light with highest sensitivity. 
The spectrum of yellowish green light emitted from a luminous paint 
contains wavelengths in the range of from four hundred and several tens nm 
to six hundred and several tens nm. It is preferable to make the 
light-emitting layer 2 of a phosphorescent paint which emits visible 
excited light in a spectrum near those wavelengths, for thereby allowing 
the observer to visually recognize desired characters, symbols, or other 
indicia with the light emitted from both the luminous paint layer 1 and 
the light-emitting layer 2. 
The light-emitting layer 2 may be coated with a combination of 
phosphorescent paints that emit respective lights of three primaries, 
i.e., red, green, and blue. If these phosphorescent paints are coated and 
adjusted such that their emitted lights of three primaries will be 
separated, the light-emitting layer 2 may look like a photograph-like, 
glossy print including full colors, gradations, or intermediate colors, 
thus providing an aesthetically pleasing appearance. 
The sheet 10 may be applied to a tape cassette (casing) 40 as shown in FIG. 
4, or may be applied to a tape cassette storage case 50 as shown in FIG. 
5. 
Alternatively, a luminous paint and a phosphorescent paint may be coated 
directly on a tape cassette or a tape cassette storage case thereby to 
form the luminous paint layer 1 and the light-emitting layer 2 thereon. In 
this case, an area of the tape cassette or the tape cassette storage case 
where the light-emitting layer 2 is to be formed should preferably be 
coated with a pigment of white or the like that will reflect light well or 
formed of a white material before a phosphorescent paint is coated. 
In the embodiment shown in FIG. 1, the luminous paint layer 1 is positioned 
adjacent to the light-emitting layer 2. However, the luminous paint layer 
1 and the light-emitting layer 2 may be formed in patterns different from 
the pattern shown in FIG. 1. For example, FIG. 6 shows a sheet according 
to another embodiment which has a luminous paint layer 1 disposed in a 
shape surrounding a light-emitting layer 2. A sheet according to still 
another embodiment shown in FIG. 7 has luminous paint layers 1 disposed in 
superposed relation to a light-emitting layer 2. 
In the above embodiments, the sheet 10 has the light-emitting layer 2 and 
the luminous paint layer 1 which emits exciting light to stimulate the 
phosphorescent paint of the light-emitting layer 2. However, the present 
invention is not limited to the above details, but may be applied to 
various other configurations. 
More specifically, the principles of the present invention are also 
applicable to the provision of a luminous paint layer and a light-emitting 
layer on a magnetooptical disk, a phase-change disk, and any of various 
other information recording mediums in the form of disks, cards, sheets, 
or the like, a storage case for such information recording mediums, a 
label for use with such information recording mediums, etc. 
FIGS. 8A and 8B illustrate a tape cassette 41 to which the principles of 
the present invention are applied. 
As shown in FIG. 8A, the tape cassette 41 has a label 70 comprising a 
luminous paint resin layer 71 formed of synthetic resin containing a 
luminous paint, a light-emitting layer 2 formed of a phosphorescent paint 
coated on the luminous paint resin layer 71, and a writable layer 4 
disposed on the light-emitting layer 2. The label 70 allows the user to 
visually observe characters, symbols, or other indicia written on the 
writable layer 4 with good visibility. 
The principles of the present invention are also applicable to an optical 
disk having pits formed in a surface thereof as representing information 
signals, a reflecting film disposed over the pits, and a photo-setting 
protective film disposed on the reflecting film. The luminous paint layer 
1 and the light-emitting layer 2 may be disposed in various shapes on an 
unrecorded area of the optical disk. 
The principles of the present invention are also applicable to flanged tape 
reels housed in a tape cassette with a magnetic tape wound on the flanged 
tape reels. 
FIG. 9 shows in exploded perspective a magnetic recording medium (tape 
cassette) 100 having flanged tape reels 200 with a magnetic tape 120 wound 
thereon. 
The tape cassette 100 comprises an upper shell 101, a lower shell 102 
joined thereto, and a pair of flanged tape reels 200 with a magnetic tape 
120 wound thereon, the flanged tape reels 200 being housed in the upper 
and lower shells 101, 102. A lid assembly 103 is angularly movably mounted 
on a front end of the upper and lower shells 101, 102. 
Each of the reels 200 comprises an upper flange 201, a lower flange 202, 
and a hub 203 interconnecting the upper and lower flanges 201, 202, the 
magnetic tape 120 being wound around the hub 203. 
The upper shell 101 has a transparent or semi-transparent window 100a for 
allowing the user to visually observe the upper flanges 201 of one of the 
reels 200 from outside of the tape cassette 100. The upper flange 201 of 
one of the reels 200 which can be observed through the window 100a is 
shown in FIG. 10. 
As shown in FIG. 10, the upper flange 201 has arcuate patterns of the 
luminous paint layer 1 and the light-emitting layer 2 for emitting light 
which permits the user to tell one side from the other of the tape 
cassette 100. The light emitted from the luminous paint layer 1 and the 
light-emitting layer 2 may be used to illuminate characters, symbols, or 
other indicia for the user to read details of recorded materials. 
Therefore, the user finds it easy to load the tape cassette 100 into or 
unload the tape cassette 100 from a tape playback device or otherwise 
handle the tape cassette 100 in a dark room or under dark conditions. 
The present invention is further applicable to a casing which houses a 
recording medium therein, such as a floppy disk (FD), a minidisk (MD), or 
the like. 
FIG. 11 shows a floppy disk 300 having a casing 301 which accommodates a 
magnetic sheet 80 therein according to the present invention. As shown in 
FIG. 11, the luminous paint layer 1 and the light-emitting layer 2 are 
disposed on the casing 301. 
FIGS. 12A through 12C show a minidisk having a casing 302 which 
accommodates a magnetooptical disk 90 therein according to the present 
invention. As shown in FIG. 12A, the luminous paint layer 1 and the 
light-emitting layer 2 are disposed on the casing 302. 
The sheet 10 shown in FIG. 1 may be used as a card 61 and a label 62 housed 
in a storage case 303 for an information recording medium such as an FD, 
as shown in FIG. 13. The luminous paint layer 1 and the light-emitting 
layer 2 are disposed in various shapes in the vicinity of characters, 
symbols, and other indicia on the card 61 and the label 62. 
The principles of the present invention are not limited to use on a storage 
case for housing a single information recording medium, but are applicable 
to use on a storage case 304 for housing a plurality of information 
recording mediums, as shown in FIG. 14. 
The writable layer formed on the information recording medium, the storage 
case for an information recording medium, or the sheet for an information 
recording medium may be positioned in a range that can be illuminated by 
light emitted from the light-emitting layer 2, rather than on the 
light-emitting layer 2. 
The phosphorescent paint and the luminous paint are not limited to the 
specific examples, but may be of various other materials. 
Having described preferred embodiments of the invention with reference to 
the accompanying drawings, it is to be understood that the invention is 
not limited to those precise embodiments and that various changes and 
modifications could be effected by one skilled in the art without 
departing from the spirit or scope of the invention as defined in the 
appended claims.