JPH0963232A - Recording medium storage cassette - Google Patents

Abstract

(57) Abstract: For example, in a tape cassette in which a magnetic tape is stored as a recording medium in a cassette housing, modulation noise due to vibration generated when the cassette is used is reduced. At least a part of the cassette housing is formed of a cellulosic resin. For example, on the outer surface of the shell 3,
The plate members 40 and 41 formed of a cellulosic resin are bonded. As a result, the good vibration damping property of the cellulosic resin reduces the vibration when the cassette is used, and as a result, the modulation noise is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium accommodating cassette, and more particularly to a recording medium accommodating cassette for improving modulation noise.

[0002]

2. Description of the Related Art As a recording medium accommodating cassette, for example, a tape cassette accommodating a magnetic tape generally has a cassette case made of a resin material such as ABS (acrylonitrile butadiene styrene) or PS (polystyrene).

When this tape cassette is used, the cassette itself vibrates slightly due to the influence of the vibration of the drive system on the magnetic recording / reproducing apparatus (cassette deck) side and the reproduced sound pressure. In this case, since the resin such as ABS and PS used in the conventional tape cassette is not particularly excellent in the vibration damping property, the vibration of the cassette housing is directly transmitted to the internal magnetic tape, and as a result, the magnetic tape together with the cassette housing Will also vibrate.

[0004]

When the magnetic tape vibrates in this way, the modulation noise component for the recording / reproducing signal increases. Due to the increase of the modulation noise, the reproduced sound quality becomes different from the original sound quality, which is not preferable. As a countermeasure against this, a structure in which the guide block arranged in the traveling path of the magnetic tape is separated from the cassette housing has been conventionally implemented, but the effect cannot be said to be sufficient.

The present invention has been made for the purpose of solving such problems.

[0006]

In order to achieve the above-mentioned object, the present invention provides a recording medium storage cassette in which a recording medium is stored in a cassette housing, and at least a part of the cassette housing is made of a cellulosic resin. It is formed. In this case, 5 to 100% by weight of an inorganic filler is added to the cellulosic resin. In the present invention, the good vibration damping property of the cellulosic resin can effectively reduce the vibration of the cassette housing when the cassette is used. Therefore, modulation noise for the recording / reproducing signal is reduced, and recording / reproducing with excellent sound quality becomes possible. Further, by adding an inorganic filler to the cellulosic resin, dimensional change due to water absorption (moisture absorption) can be suppressed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The most preferred embodiment of the present invention will be described in detail below with reference to the drawings. In this embodiment, a case where the present invention is applied to a so-called audio compact cassette as a recording medium storage cassette will be described.

A first embodiment is shown in FIGS. 1 and 2. In the figure, 1 is a compact audio cassette (tape cassette) as a whole, and 2 is its box body. This cassette box body 2 is formed by integrally fixing an upper shell 3 and a lower shell 4 of substantially symmetrical shapes by screwing. To be done.

The upper shell 3 and the lower shell 4 respectively have a pair of hub drive shaft insertion holes 5a, 5b and 6a on the left and right of the central portion.
6b is formed, and a magnetic tape 7 as a recording medium is formed in the cassette housing corresponding to the hub drive shaft insertion hole.
A pair of hubs around which a supply hub 8 and a take-up hub 9 are wound.
Is rotatably housed. The magnetic tape 7 is wound around the hubs 8 and 9 with both ends thereof fixed to the supply-side hub 8 and the winding-side hub 9, respectively.

Between the hubs 8 and 9 and the upper shell 3, and between the hubs 8 and 9 and the lower shell 4, the hubs 8 and 9 rotate smoothly and are wound around the hubs 8 and 9. Liner sheets 10a and 10 for preventing winding disorder of the magnetic tape 7
b is arranged.

An opening 11 into which a magnetic head or a pinch roller is inserted is provided on the front surface of the cassette housing 2, and the magnetic tape 7 drawn out from the supply side hub 8 in the cassette housing has this opening 11. A tape traveling path is formed so that the tape can be wound around the winding hub 9.

Guide pins 12a and 12b are provided on the left and right sides of the opening 11 on the lower shell 4 side, and a shaft column 13a, which is provided side by side with the guide pins 12a and 12b, is provided. Guide rollers 14a and 14 are provided on 13b.
b is rotatably supported and these guide pins 1
The magnetic tape 7 is guided along the traveling path by the 2a, 12b and the guide rollers 14a, 14b.

Further, inside the cassette housing 2,
A guide block 15 for guiding the magnetic tape 7 passing through the opening 11 is provided. The guide block 15 is formed separately from the cassette housing 2, and the partition wall portion 1 that separates the opening portion 11 from the storage portions of the hubs 8 and 9 is formed.
5a and guide protrusions 15b, 15c, 15d, 15e, 15 protruding from the partition wall 15a toward the opening 11 side.
The guide projections 15b to 15g are slidably in contact with the magnetic tape 7 passing through the opening 11 to guide it.

At the upper and lower parts of the guide block 15,
Ring-shaped protrusions 16a, 16b and 17a, 17b are integrally formed at symmetrical positions, respectively, and these ring-shaped protrusions 16a, 16b and 17a, 17b are formed in the upper shell 3 and the lower shell 4, respectively. The guide block 15 is fitted to 18a, 18b and 19a, 19b and is assembled at a predetermined position in the cassette housing.

A shield plate 20 is incorporated in the central portion of the guide block 15, that is, a concave portion between the guide protrusions 15d and 15e, and a magnetic head pressure bonding pad 21 is located in front of the shield plate 20. It is arranged.

Further, window holes 22 and 23 for visually observing the magnetic tape 7 in the cassette housing are formed in the central portions of the upper shell 3 and the lower shell 4, respectively.
Transparent window plates 24 and 25 are fixed to 2 and 23 from the inner surface sides of the upper shell 3 and the lower shell 4, respectively.

The front portions of the upper shell 3 and the lower shell 4, that is, the portions forming the opening 11 are formed by bulging into trapezoidal shapes, and the trapezoidal bulging portions 26 and 27 are capped respectively. Stan insertion holes 28a, 28b and 29a, 29
b and a reference hole for positioning the cassette are formed.

In the cassette of this embodiment, the reference hole for positioning the cassette is formed by utilizing a part of the guide block 15, that is, the holes 18a, 18b and 19a, 19b.
The inner circumferential holes of the ring-shaped projections 16a, 16b and 17a, 17b of the guide block 15 which are fitted and exposed to the cassette positioning reference holes 30a, 30b and 31a, respectively.
31b.

When the cassette 1 constructed as described above is mounted on the cassette deck, first, the positioning pins on the cassette deck side are engaged with the cassette positioning reference holes 31a and 31b (or 30a and 30b). The positioning is performed, and at the same time, the hub drive shaft insertion holes 5a, 5
The hub drive shaft on the cassette deck side is inserted into b and 6a and 6b to engage with the hubs 8 and 9, and the capstan on the cassette deck side is inserted into the capstan insertion holes 28b and 29b (or 28a and 29a). It

When the cassette deck is in the play state, the magnetic head and the pinch roller on the side of the cassette deck are inserted into the opening 11, the magnetic head contacts the magnetic tape, and the pinch roller sandwiches the magnetic tape to form a capstan. By pressing and pressing, and in this state, the hub drive shaft and the capstan are driven to rotate, the magnetic tape runs, and recording or reproduction is performed.

When this cassette is used, the vibration transmitted from the drive system of the cassette deck may adversely affect the recording / reproducing signal of the magnetic tape. Therefore, in the cassette 1 of this example, the cassette housing 2 is constructed as a countermeasure. The upper shell 3 and the lower shell 4 are entirely made of a cellulosic resin. That is, the inventors of the present invention pay attention to the vibration damping property of the cellulosic resin and apply it to the cassette to suppress the vibration transmitted to the magnetic tape.

Cellulose resin is composed of glucose (C ₆ H ₁₂
Various derivatives obtained by dehydration condensation of O ₆ ) and produced by esterifying or etherifying a part or all of hydroxyl groups of glucose are cellulose resins.

The cellulose resin can be roughly classified into a cellulose ester obtained by esterification and a cellulose ether obtained by etherification. Examples of the cellulose ester include cellulose nitrate, cellulose acetate, cellulose butyrate acetate, and cellulose propionate. Representative examples of the cellulose ether include ethyl cellulose. Table 1 shows the physical properties of these cellulose resins.

[0024]

[Table 1]

Among these various cellulose resins, cellulose acetate resin is used as the most suitable material for the case of the tape cassette in this example. This cellulose acetate resin is particularly excellent in vibration damping property, and its characteristics are shown in FIG.

That is, in FIG. 5, A is a vibration damping characteristic of cellulose acetate resin, and in order to compare with this, as a resin material used for a general cassette, FIG. 5B shows ABS (acrylonitrile butadiene styrene) resin, and FIG. P to C
The vibration damping characteristics of S (polystyrene) resin are shown.
This characteristic is obtained by measuring the time for which the amplitude is attenuated when a constant vibration is applied to each resin. As is clear by comparing these, the amplitudes of ABS resin and PS resin are It takes 0.4 seconds or more to be attenuated to near zero, whereas the cellulose acetate resin requires less than a third of the time. Therefore, it can be seen that the cellulose acetate resin has a significantly superior vibration damping property as compared with the ABS resin and the PS resin.

As described above, the cellulose acetate resin is excellent in the vibration damping property, but on the other hand, it has a high water absorption (moisture absorption) ratio, so that the dimensional change is likely to occur. When this cellulose acetate resin is used for the housing of a tape cassette, if the dimensions change, it will not be possible to satisfy the dimensional specifications as a tape cassette, so the water absorption rate (24 hours storage in water) is preferably 2% or less. Must be kept below 1%.

As a means for this, in this example, the water absorption rate is suppressed by adding a SiO ₂ compound (silica) as an inorganic filler to the cellulose acetate resin. That is, S
Since the inorganic filler such as the iO ₂ compound hardly absorbs water, the water absorption of the resin can be effectively suppressed.

When the amount of the SiO ₂ compound added to the cellulose acetate resin is 4% by weight or less, there is almost no effect.
In the range of 5 to 100% by weight, the water absorption is adjusted to 2% or less, preferably 1% or less. However, SiO ₂
Since the vibration damping property of the cellulose acetate resin is adversely affected even if the amount of the compound added is too large, in order to suppress the water absorption rate to 2% or less without impairing the vibration damping property of the cellulose acetate resin, the SiO ₂ compound A proper amount of addition is about 15% by weight.

As the inorganic filler added to the cellulose acetate resin, calcium carbonate, aluminum silicate, carbon fiber, zinc oxide, titanium oxide, barium sulfate, calcium silicate, etc. may be used in addition to the SiO ₂ compound. You can

As described above, the cellulose acetate resin is coated with SiO ₂
By molding the upper shell 3 and the lower shell 4 of the cassette housing 2 with a cellulosic resin material to which an inorganic filler such as a compound is added, dimensional changes due to water absorption can be suppressed and good vibration damping properties of the cellulose acetate resin can be suppressed. Thus, it is possible to effectively reduce the vibration generated in the cassette housing when the cassette is used.

By thus reducing the vibration of the cassette housing 2 when the cassette is used, the magnetic tape 7 inside the cassette housing 2 hardly oscillates, so that the modulation noise for the recording / reproducing signal is reduced. Will be reduced.

The effect of reducing this modulation noise is shown in FIG.
This is 6300 for each magnetic tape using two cassettes, the conventional tape cassette and the tape cassette of this example.
The results of measuring the modulation noise when a Hz signal is recorded and reproduced are shown. The line a in the figure is the data of the cassette of this example, and the line b is the data of the conventional cassette. From this result, it can be seen at a glance that the cassette of this example clearly has improved modulation noise as compared with the conventional cassette.

As described above, in the cassette 1 of this embodiment, the modulation noise is reduced by the vibration damping effect of the cellulose resin, so that the recording / reproduction with excellent sound quality becomes possible.

In the cassette 1 of this embodiment, the upper shell 3 and the lower shell 4 constituting the cassette housing 2 are entirely molded with a cellulosic resin material.
The upper shell 3 and the lower shell 4 are formed as separate members from, for example, transparent PS resin, and are joined to the upper shell 3 and the lower shell 4 by secondary means such as adhesion.

3 and 4 show a second embodiment of the present invention. Also in this second embodiment, the audio compact cassette is shown as the recording medium storage cassette, and
The same parts as those of the embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the cassette 1 of this example, a part of the cassette housing 2 is formed of a cellulosic resin. That is, in this example, plate-like molded products (hereinafter referred to as cellulose resin plate materials) 40 and 41 molded of a cellulose-based resin material obtained by adding about 15% by weight of a SiO ₂ compound as an inorganic filler to a cellulose acetate resin are used as upper shell And the outer surface of the main body of the lower shell 4 with an adhesive. The main bodies of the upper shell 3 and the lower shell 4 are made of generally used ABS resin, PS resin or the like.

As shown in the figure, the portion where the cellulose resin plate members 40 and 41 are joined is a flat portion rearward of the hub drive shaft insertion holes 5a, 5b and 6a, 6b of the shells 3 and 4, and a trapezoidal bulge portion. It is preferable that a part of 26 and 27 can have a relatively large area.

Even when a part of the cassette casing 2 is formed of a cellulosic resin material as described above, vibration generated in the cassette casing 2 when the cassette is used can be reduced due to the vibration damping property of the cellulosic resin. Therefore, the effect of improving the modulation noise according to the above-described first embodiment can be obtained.

In the cassette 1 of this example, the main bodies of the upper shell 3 and the lower shell 4 and the cellulose resin plate members 40, 4
The joining means with 1 is not limited to an adhesive, and a method such as welding may be used. Further, the main body portions of the upper shell 3 and the lower shell 4 and the portions of the cellulose resin plate members 40 and 41 may be integrally molded by a two-color molding method.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. In the embodiments, the audio compact cassette is shown as the recording medium storage cassette, but the present invention is not limited to this, and is widely applicable to video cassettes, DAT (digital audio tape recorder) cassettes, and disk cassettes. .

[0042]

As is apparent from the above embodiments, according to the present invention, it is possible to form a cassette housing which is not easily affected by vibration due to the good vibration damping property of the cellulosic resin. As a result, modulation noise when using the cassette is reduced, and recording / reproduction with excellent sound quality can be performed. Further, by adding an inorganic filler to the cellulosic resin to suppress the water absorption rate, it is possible to ensure dimensional stability in a humid environment.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a cassette according to a first embodiment.

FIG. 2 is an exploded perspective view of the same.

FIG. 3 is an exploded perspective view of a cassette showing a second embodiment.

FIG. 4 is a partially cutaway perspective view of the same.

FIG. 5 is an explanatory diagram of vibration damping properties of cellulose resin.

FIG. 6 is an explanatory diagram of a modulation noise reduction effect.

[Explanation of symbols]

 1 cassette 2 cassette housing 3 upper shell 4 lower shell 7 magnetic tape (recording medium) 40,41 cellulose resin plate material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Abiko 200 Terashimacho, Hamamatsu City, Shizuoka Prefecture Kawai Musical Instrument Co., Ltd. Inside the factory

Claims (3)

[Claims] 1. A recording medium storage cassette in which a recording medium is stored in a cassette housing, wherein at least a part of the cassette housing is formed of a cellulosic resin. 2. The recording medium storage cassette according to claim 1, wherein an inorganic filler is added to the cellulosic resin in an amount of 5 to 100% by weight. 3. The recording medium storage cassette according to claim 2, wherein the water absorption rate of the cellulose resin is 2% or less.