JPH08263963A - Recording medium encasing case and it forming method - Google Patents

Abstract

PURPOSE: To provide an encasing case having a good design appearance by forming the encasing case of two colors with its outer peripheral part as an opaque part and its planar part as a transparent or translucent part. CONSTITUTION: Upper and lower cassette halves 32 and 33 are formed by a two color forming method using transparent or a translucent resin materials and peripheral side wall parts 36 and 37 having fixed heights are formed of opaque resins on the outer peripheral parts of planar parts 34 and 35 formed of transparent or translucent resin materials. Pairs of left and right symmetrical hub holes 38a and 38b and 39a and 39b are provided in the transparent or translucent planar parts 34 and 35 and trapezoidal projecting surfaces 41 and 42 for forming the front opening part 40 of a cassette main body 31 are formed of opaque resin materials in the center of the front side integrally with the peripheral side wall parts 36 and 37. Thus, an encasing case having a good design appearance, with its planar parts hemmed by the narrow opaque parts, for a recording medium such as a tape cassette and the like is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium storage case such as a tape cassette for storing magnetic tapes such as audio and video and a disc cartridge for storing optical discs.

[0002]

2. Description of the Related Art In a recording medium storage case, for example, an audio tape cassette (compact tape cassette), a cassette body 1 is formed by combining upper and lower cassette halves 2 and 3 as shown in FIGS. . That is, both cassette halves 2 and 3 are formed in a box shape having peripheral side wall portions 6 and 7 having a constant height around the flat portions 4 and 5, and the central portions of the flat portions 4 and 5 are housed. Transparent surface portions 4a and 5 as windows so that the magnetic tape can be visually recognized from the outside.
a is formed and hub holes 8a, 8b and 9 are formed at symmetrical positions.
a and 9b are provided. Further, trapezoidal convex surface portions 11 and 12 that form the front opening portion 10 of the cassette body 1 are formed in the center portions on the front surface side of the flat surface portions 4 and 5, and cassette positioning holes 13a, 13b and 1
4a and 14b are bored, and capstan insertion holes 15a, 15b and 16a, 16b are bored at symmetrical positions outside thereof. In addition, the flat portion 5 of the lower cassette half 3
Tape guide roller placement recesses 17a and 17b are formed on the inner surfaces of both front sides of the shaft pin 18 at the center thereof.
a and 18b are projected, and tape guide pins 19a and 19b are projected near them. Incidentally, only the tape guide roller placement recesses are formed on the inner surface sides of the front surface sides of the flat surface portion 4 of the upper cassette half 2 so as to correspond to the tape guide roller placement recesses 17a and 17b on the lower cassette half 3 side.

Then, on the back side of the cassette body 1, an erroneous erasure prevention concave portion 20 as a detection function portion of the contained magnetic tape is provided.
a, 20b and switching detection recesses 21a, 2 such as tape sensitivity
1b is formed. The erroneous erasure prevention recesses 20a, 2
0b and the switching detection recesses 21a and 21b are formed over the upper and lower cassette halves 2 and 3, and the rear side wall portions 6a and 7a of the peripheral side wall portions 6 and 7 of both cassette halves 2 and 3.
It is formed so as to extend across.

The erroneous erasure prevention recesses 20a and 20b are integrally formed continuously on both sides of the rear side wall portions 6a and 7a of both cassette halves 2 and 3 from the symmetrical position to the inner surfaces of the plane portions 4 and 5. The ribs 22a, 22b (the ribs on the upper cassette half 2 side are formed symmetrically with the ribs on the lower cassette half 3 side, so are not shown). Erase prevention recess 20a
To the opening 20a ₁ on the side, and to the opening 20b ₁ on the side of the other erroneous erasure prevention recess 20b in the upper cassette half 2,
The erroneous erasure prevention claws 23a and 23b facing the openings of the cassette halves facing each other are provided so as to be breakable. Further, the switching detection recesses 21a and 21b are integrally formed with the ribs 25a which are formed continuously in the central portions of the rear side wall portions 6a and 7a of both cassette halves 2 and 3 from the symmetrical positions to the inner surfaces of the flat portions 4 and 5. , 25b (note that the ribs on the upper cassette half side are formed symmetrically with the ribs on the lower cassette half 3 side, so they are not shown).

The upper and lower cassette halves 2, 3
Is the other surface portion 4 of the flat surface portions 4 and 5 excluding the transparent surface portions 4a and 5a.
b, 5b and the convex surface portions 11, 12 to the peripheral side wall portions 6, 7 are formed as opaque (generally black) surface portions, and the erroneous erasure prevention recesses 20a, 20b, the switching detection recesses 21a, 21b, and mechanical parts are on the front surface side. It is formed so as to be concealed when viewed from above. Particularly, as shown in FIGS. 8 and 9, the width dimension a in the front-rear direction of the opaque surface portions 4b and 5b on the back side wall portions 6a and 7a side is set to the erroneous erasure prevention recess 20a. , 20b, that is, a width dimension b from the back surface to the inner end surfaces of the ribs 22a, 22b.

The upper and lower cassette halves 2 and 3 thus formed are made of a transparent resin material and an opaque resin material by a two-color injection molding method, and the transparent portions 4a and 5a of the plane portions 4 and 5 and the peripheral side wall portion 6 are formed. , 7 are integrally molded.

The upper and lower cassette halves 2 and 3 are overlapped with each other, and the magnetic tape wound between a pair of hubs is housed in the space between the upper and lower cassette halves together with other mechanical parts. The tape cassette is assembled by tightening and uniting.

[0008]

As described above, in the upper and lower cassette halves of the conventional tape cassette, the central surface of the flat portion is transparent, and the magnetic tape to be housed can be seen through from the outside to check the running state, the remaining amount, and the like. It is visible and the front and back surfaces are opaque, and the built-in mechanical parts, erroneous erasure prevention recess, tape sensitivity switching detection recess, etc. are concealed so that the appearance is not damaged, but the opaque part is wide, especially the rear part. The opaque portion needs to be formed in a width that can conceal the erroneous erasure prevention concave portion and the tape sensitivity switching detection concave portion in order to prevent a reduction in commercial value due to the opaque irregular shape being exposed. Since there are many restrictions on the shape, the degree of freedom in design is low and it is impossible to deal with various designs.

The present invention has been made in view of the above point, and the degree of freedom in design is increased, and even when the design is changed, it can be manufactured by a simplified mold structure, and productivity can be improved. An object of the present invention is to provide a storage case for a recording medium such as a tape cassette.

[0010]

In order to achieve the above object, the present invention is a two-color molding using an opaque resin and a transparent or semitransparent resin, and an opaque portion on the outer peripheral portion and a transparent or semitransparent portion on the flat portion. A recording medium storage case having the opaque portion at least on the side of the outer peripheral portion on which the detection function unit of the storage recording medium is arranged is formed narrower than the detection function unit, and the detection function unit is a transparent or translucent portion of a flat surface portion. It is formed integrally with.

[0011]

The recording medium storage case molded in this way is
Even if the opaque portion of the outer peripheral portion is formed narrowly, the detection function portion of the stored recording medium such as the erroneous erasure prevention concave portion and the sensitivity switching detection concave portion is formed integrally with the transparent or semi-transparent portion of the flat portion, Therefore, the appearance of the opaque portion is not expressed as an opaque irregular shape, the appearance is not impaired, and the width of the opaque portion of the outer peripheral portion can be set arbitrarily, so that various designs can be accommodated and the degree of freedom in design is increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4, and a case where the present invention is applied to a tape cassette similar to the above-mentioned conventional example will be described.

1 to 4, reference numeral 30 denotes an entire tape cassette to which the present invention is applied, reference numeral 31 denotes a cassette body, and an upper cassette half 32 and a lower cassette half 3 are provided.
It is configured by combining three.

The upper and lower cassette halves 32 and 33 are
A peripheral side wall portion 3 having a constant height is formed on the outer peripheral portions of the flat surface portions 34 and 35 which are molded by a two-color molding method using a transparent or semitransparent resin material and an opaque resin material.
6 and 37 are made of an opaque resin, and a pair of hub holes 38a, 38b and 39a, 39b are provided symmetrically on the transparent or semitransparent plane portions 34 and 35, and the cassette main body is provided at the front center portion. The trapezoidal convex surface portions 41 and 42 forming the front surface opening portion 40 of the reference numeral 31 are peripheral side wall portions 36 and 3.
It is molded integrally with 7 by an opaque resin material. The trapezoidal convex surface portions 41 and 42 of the flat surface portions 34 and 35 are provided with cassette positioning holes 43a, 43b and 44a, 44b at left and right symmetrical positions, and capstan insertion holes 45a at the left and right symmetrical positions. 45b and 46a, 46b
Has been drilled.

Tape guide roller placement recesses 47a, 47b are formed on the inner surfaces of both sides of the front surface, which is a transparent or translucent portion of the flat surface portion 35 of the lower cassette half 3, and shaft pins 48a, 48b are formed at the centers thereof. And the tape guide pins 49a and 49b are provided in the vicinity thereof. Although not shown, the lower cassette half 33 is not shown on the inner surface side of the front surface both sides of the flat surface portion 34 of the upper cassette half 32.
Only the tape guide roller arrangement concave portions are formed corresponding to the side tape guide roller arrangement concave portions 47a and 47b.

On the back surface 50 side of the cassette body 31, erroneous erasure prevention recesses 51a, 51b and a tape sensitivity switching detection recess 52a, which function as a detection function of the stored magnetic tape, are provided.
52b is formed from the rear side wall portions 36a, 37a of the peripheral side wall portions 36, 37 that are opaque portions of the upper and lower cassette halves 32, 33 to the rear surface of the flat surface portions 34, 35 that are transparent or translucent portions. An opening is formed across the portions 36a and 37a.

Of these, erroneous erasure prevention recesses 51a and 51b
At the left and right symmetrical positions on both sides of the back surface 50 of the cassette body 31, the back side wall portions 36 of the upper and lower cassette halves 32, 33.
openings 51a ₁ and 51b formed across a and 37a
Plane part 3 which is a transparent or semi-transparent part corresponding to the inside of ₁
Ribs 53a and 53b are formed on the rear end sides of the inner surfaces of 4, 35. The openings 51a ₁ and 51b ₁ are provided with the erroneous erasure prevention claw 54.
One erroneous erasure prevention claw 54a is closed by a and 54b.
Is formed integrally with the lower cassette half 33 on the rear side wall 37a side, and the other erroneous erasure prevention claw 54b is integrally formed on the rear side wall 36a side of the upper cassette half 32 as opaque.

The ribs 53a and 53b forming the erroneous erasure prevention recesses 51a and 51b are transparent or semi-integrated in a state of being half-divided in the horizontal direction on the inner surfaces of the flat portions 34 and 35 of the upper and lower cassette halves 32 and 33, respectively. Both ends of the ribs 53a, 53b are formed as transparent and are formed discontinuously at a required interval with respect to the back side wall parts 36a, 37a which are opaque parts, as shown in FIG. The interval dimension c of the continuous portion is set to be smaller than the thickness dimension d of the erroneous erasure prevention claws 54a and 54b. In addition, the back wall portion 36a,
Both ends of the ribs 53a and 53b facing the 37a are formed as tapered end surfaces 53a ₁ , 53a ₂ and 53b ₁ , 53b ₂ which are inclined outward with respect to the erroneous erasure prevention recesses 56a and 56b.

Further, a switching detection concave portion 52 such as tape sensitivity is detected.
Reference numerals a and 52b are openings 52a for detection, which are formed at symmetrical positions in the central portion of the back surface 50 of the cassette body 31 and across the back wall portions 36a and 37a which are opaque portions of the upper and lower cassette halves 32 and 33. ₁ , 52b ₁ and this opening 52
Ribs 55 integrated with the flat portions are formed on the inner surfaces of the flat portions 34 and 35 which are transparent or semitransparent corresponding to the insides of a ₁ and 52b ₁ .
It is formed by a and 55b.

The ribs 55a and 55b forming the switching detection recesses 52a and 52b are also flat portions 34 and 3 which are transparent or translucent portions of the upper and lower cassette halves 32 and 33, respectively.
5, the ribs 55a and 55b are formed so as to integrally project from the inner surface of the rib 5 in a state of being half-divided in the horizontal direction, and the ribs 55a and 55b have a predetermined gap with respect to the back wall portions 36a and 37a which are opaque portions as shown in FIG. It is placed discontinuously. In addition, both ends of the ribs 55a and 55b also have tapered surfaces 5 that are inclined outward with respect to the switching detection recesses 52a and 52b.
5a ₁ , 55a ₂ and 55b ₁ , 55b ₂ . The back wall portions 36a and 37a and the rib 55a
The distance dimension e of the discontinuity between the and 55b should be as small as possible.

The upper and lower cassette halves 32, 33 of the cassette body 31 of the present embodiment thus formed are two-color molded from a transparent or semitransparent resin material and an opaque resin material, and the flat portions 34, 35 are trapezoidal. Except for the convex surface portions 41 and 42, it is molded as a transparent or semitransparent portion from a transparent or semitransparent resin material, and the peripheral side wall portions 36 and 37, that is, the rear side wall portions 36a and 37a to both side surface wall portions 36b, 36c and 37b, 37.
front side wall parts 36d, 36e and 37d, 3 via c
The peripheral side wall portions 36 and 37 over 7e and the trapezoidal convex surface portions 41 and 42 described above are formed of an opaque resin material as opaque portions.

As the transparent resin material for molding the transparent or translucent portion, polystyrene resin, polypropylene resin,
Polyester resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene resin, methacrylic resin (methyl methacrylate resin), polycarbonate resin, etc. can be used. A colorant such as a pigment is added for use. On the other hand, as the opaque resin material, acrylonitol-butadiene-styrene (ABS) resin, high-impact styrene resin, or the like can be used.

The cassette body 31 formed by combining the upper and lower cassette halves 32 and 33 formed in this way has ribs 53a and 53b forming erroneous erasure prevention recesses 51a and 51b and a switching detection recess such as tape sensitivity. 5
Ribs 55a and 55b forming 2a and 52b are integrally formed as transparent or translucent portions on flat surface portions 34 and 35 as transparent or translucent portions, and are separated from rear wall portions 36a and 37a as opaque portions. By doing so, the appearance as an opaque irregularly shaped portion is prevented without impairing the transparency or translucency.

Light transmitted through the ribs 53a, 53b and 55a, 55b formed as transparent or opaque portions is tapered end faces 53a ₁ , 53a ₂ , 53b ₁ , 53b _2.
And 55a ₁ , 55a ₂ , 55b ₁ and 55b ₂ are reflected in a fixed direction, unnecessary diffuse reflection does not occur, and is not visually recognized as an irregular shape portion.

The ribs 53a and 53b forming the erroneous erasure prevention recesses 51a and 51b are rear side wall portions 36a and 37, respectively.
Since the erroneous erasure prevention claws 54a, 54b are separated from the a by a distance smaller than the thickness dimension of the erroneous erasure prevention claws 54a, 54b, the broken erroneous erasure prevention claws 54a, 54b do not enter the cassette body 31 through the gap, and It is designed to prevent the occurrence of troubles such as hindering the operation.

In this way, the outer peripheral portion of the cassette main body 31, that is, the peripheral side wall portion 3 of the upper and lower cassette halves 32 and 33.
6, 37 are formed as opaque parts such as black, and the flat part 3
By forming the transparent portions 4 and 35, the transparent or semi-transparent flat portion having the pair of hub holes is narrow and surrounded by the outer peripheral wall of the opaque portion such as black. Is formed.

Next, an example of a method of molding the upper and lower cassette halves 31 and 32 of the cassette body 30 formed as described above will be described.

In the example shown in FIGS. 5 to 7, the peripheral side wall portions 36 and 3 are provided.
The core 61 for molding the flat surface portions 34 and 35 as transparent or translucent portions when the molding of the opaque portion 7 is preceded.
And a peripheral side wall portion 3 as an opaque portion having a resin passage 62.
Molding cavity 6 of 6, 37 and trapezoidal convex surface portions 41, 42
Using the molding split die 64 having three, the core 61 is provided with ribs 53a, 53b and ribs for forming the erroneous erasure prevention recesses 51a, 51b and the switching detection recesses 51a, 51b together with the molding portion such as the tape guide roller disposing recess. 55a, 55
A rib forming groove 65 for forming b is formed by engraving the required cavity c described above between the forming cavity 63 of the peripheral side wall portions 36 and 37, that is, the forming cavity 63a of the back wall portions 36a and 37a. .

Also, the rear wall portions 36a, 36 of the split mold 64 are formed.
The erasure prevention recess 51 is formed in the molding cavity 63a of 7a.
a, 51b openings 51a₁, 51b₁And erasure prevention nail
Molding portions 66 of 54a and 54b and switching detection recesses 52a,
52b opening 52a₁, 52b ₁The molding part of
It

Therefore, in order to mold the upper and lower cassette halves 31 and 32 using this molding die, first, the peripheral side wall portion 3 is made of an opaque resin material with the core 61 closed as shown in FIG.
6 and 37 are injection molded. At this time, the erroneous erasure prevention concave portion 5
1a, 51b and the openings 51a ₁ , 51b ₁ and 52a ₁ , 52b _{1 of the} switching detection recesses 52a, 52b and the erroneous erasure prevention claws 54a, 54b are also molded at the same time, but the rib molding groove 65 on the core 61 side is a rear wall. Since the ribs 36 are separated from the molding cavity 63a of the portions 36a and 37a with a space c therebetween, the opaque resin material does not flow into the rib molding groove 65.

Next, the core 61 is lowered to the position shown in FIG. As a result, the flat surface portion 34,
Thirty-five molding cavities 67 are formed. Therefore, when a transparent or translucent resin material is injected into the molding cavity 67 from the resin passage 62, the resin material is also flown into the rib molding groove 65 to integrally form the ribs 53a and 53b as shown in FIG. The transparent or semitransparent flat portions 34 and 35 are molded. The ribs 55a and 55b are also molded at the same time, although not shown. By this step, the opaque peripheral side wall portion 36,
The upper and lower cassette halves 32 and 33 in which 37 and the transparent or semitransparent flat surface portions 34 and 35 are integrated are obtained, and the ribs 53 are provided.
Since the a and 53b and the ribs 55a and 55b are formed so as to be separated from the opaque peripheral side wall portions 36 and 37 at a required distance c, the opaque resin does not mix and the opaque different shape is exposed. There is no.

As another method of molding the cassette halves 32 and 33, there is a method of molding using a plurality of molding dies. In this case, the flat surface portions 34 and 35 as transparent or translucent portions are molded. Then, the flat surface portions 34, 35 are transferred to a molding die for forming the peripheral side wall portions 36, 37 as opaque portions, and the peripheral side wall portions 36, 37 are made flat with the opaque resin material.
Molded together with 5. Also in this case, the flat portions 34 and 35 are molded by using a mold having a rib molding portion similar to the core 61 in which the molding groove 64 is formed.

As described above, the cassette body 31 of the tape cassette 30, that is, the molding dies for the upper and lower cassette halves 32 and 33 are the conventional molds for the cassette halves, that is, the erroneous erasure prevention section and the tape sensitivity switching detection section. Replacing a part of the cavity side part of the molding die for forming the opaque part wide to conceal, that is, the ribs 53a of the erroneous erasure prevention recesses 51a, 51b and the detection recesses 52a, 52b on the flat parts 34, 35 side. 53b and 55a, 55b are attached to the back wall portion 36
a, 37a and a core formed with a molding portion that is discontinuously molded can be dealt with, which can significantly reduce the molding die manufacturing cost and the manufacturing period, and the flat surface portions 34, 35.
Since the peripheral side walls 36 and 37 can be molded by a two-color molding method with a simplified mold structure even for complicated designs, it is possible to reduce the failure rate and improve the productivity by shortening the production cycle. .

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, the opaque portion may extend to the flat surface side on both sides, and the width dimension of the opaque portion of the outer peripheral surface portion can be made smaller than the thickness dimension of the peripheral wall portion. It can be adapted to various designs.

Further, the color of the opaque portion is not limited to black, but each color can be applied.

The present invention is not limited to the compact tape cassette shown in the embodiment, but can be applied to various recording medium storage cases such as disk cartridges as well as other tape cassettes. The arrangement position of each member in this case differs depending on the form. It goes without saying that the present invention can also be applied to a tape cassette or the like that does not have a tape sensitivity switching detection unit.

[0038]

As described above, according to the present invention, there is provided a recording medium storage case in which the outer peripheral portion is an opaque portion and the flat portion is a transparent or semi-transparent portion and two-color molding is performed, and at least a detection function portion is provided. Side peripheral surface part is molded into an opaque part that is narrower than the detection function part, and the part extending to the flat part side of the detection function part is molded as a transparent or translucent part integrally with the flat part, so It is possible to obtain a recording medium storage case such as a tape cassette having a good-looking design in which the transparent or semitransparent plane portion is bordered by the opaque portion having a narrow width without the detection function portion being exposed as an opaque irregular shape.

The design change can be dealt with by replacing a part of the cavity side with the conventional molding die,
It is possible to significantly reduce the manufacturing cost and the manufacturing period of the molding die, and it is possible to mold even a complicated design with a simplified mold structure, which reduces the failure rate and the productivity by shortening the molding cycle. It is possible to improve.

[Brief description of drawings]

FIG. 1 is a plan view of an inner surface side of a cassette half in an example tape cassette according to the present invention.

FIG. 2 is a plan view of an example tape cassette according to the present invention.

3 is an enlarged plan view of an erroneous erasure prevention portion in the cassette half shown in FIG.

FIG. 4 is an enlarged plan view of a tape sensitivity switching detection portion in the cassette half shown in FIG.

FIG. 5 is a sectional view of an essential part showing a primary molding step of a cassette half of an example in the molding method of the present invention.

6 is a cross-sectional view of a main part showing a core moving step following the primary molding step shown in FIG.

FIG. 7 is a cross-sectional view of an essential view showing a secondary molding step following the step shown in FIG.

FIG. 8 is a plan view of a conventional tape cassette.

FIG. 9 is a plan view of an inner surface side of a lower cassette half in a conventional tape cassette.

[Explanation of symbols]

 31 cassette body 32 upper cassette half 33 lower cassette half 34,35 flat surface portion 36,37 peripheral wall portion 36a, 37a rear wall portion 51a, 51b erroneous erasure prevention concave portion 52a, 52b switching detection concave portion 53a, 53b rib 54a, 54b erroneous erasure Prevention claws 55a, 55b Ribs

Claims (6)

[Claims] 1. A recording medium storage case which is two-color molded from an opaque resin and a transparent or semitransparent resin, and has an opaque portion on the outer peripheral portion and a transparent or semitransparent portion on the flat surface portion, and at least the stored recording on the outer peripheral portion. A recording medium storage characterized in that an opaque portion on the side where the detection function portion of the medium is arranged is formed narrower than the detection function portion, and the detection function portion is integrally formed with the transparent or semitransparent portion of the flat surface portion. Case. 2. The detection function section is integrally formed with the transparent or semi-transparent section of the plane section through a discontinuous section between the outer peripheral section and the opaque section. Recording medium storage case described. 3. The detection function portion is integrally formed on the flat surface portion with a discontinuous portion having an interval smaller than the thickness of the breaking member between the outer peripheral portion and the opaque portion. The recording medium storage case according to claim 1. 4. An opaque resin material and a transparent or semi-transparent resin material for forming an opaque portion on an outer peripheral portion and a transparent or semi-transparent portion for a flat portion by a first molding cavity and a second molding cavity in the same molding die. A molding method for molding a recording medium storage case having: a cavity for molding a transparent or semi-transparent portion of the flat portion, wherein a molding portion for molding a detection function portion of the storage recording medium is engraved, A method for molding a recording medium storage case, characterized in that the detection function part is molded from a transparent or translucent resin at the same time as the transparent or translucent part of the flat part in the cavity. 5. The molding portion of the detection function portion is engraved in a cavity for molding the transparent or semi-transparent portion of the flat portion at a required distance from the cavity for forming the opaque portion of the outer peripheral portion. 5. The detection function part is formed discontinuously with respect to the opaque part of the outer peripheral part.
A method for molding a recording medium storage case according to. 6. The molding portion of the detection function portion is provided in a cavity for molding a transparent or semi-transparent portion of the flat portion, and a gap smaller than a thickness of a breaking member from a cavity for forming an opaque portion of the outer peripheral portion. 5. The recording according to claim 4, wherein the detection function portion is formed in a discontinuous manner at intervals so that the folding member is not inserted into the opaque portion of the outer peripheral portion. Method of forming medium storage case.