JPH0229547Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cassette-type tape recorder applied to car stereos and the like.

When the car stereo is stopped, even a cassette-type tape recorder with good sound quality can be used.
It is known from experience that when a car starts running and is subjected to severe vertical vibrations, the wah becomes louder and the sound quality deteriorates, especially when there is a lot of tape remaining.

In order to find out what this wah is like,
When we measured wah by applying 1G vertical vibration at different frequencies to an existing cassette tape recorder, we obtained the wah (RMS) characteristics shown in Figure 1. In this characteristic, it can be seen that wow of more than 1% occurs at vibrations around 40Hz and 100Hz or more, but when this is measured with audible correction, as shown in Figure 2, wow occurs at vibrations over 100Hz. (WRMS) has become less than 0.2%, a value that is hardly a problem, whereas wah at around 40Hz still exists at more than 0.2%, and it was found that this was deteriorating the sound quality.

In order to find out what causes this 40Hz wow, the structures of tape recorders and cassettes and their operations during play will be discussed with reference to FIGS. 3 to 8.

The cassette is constructed by storing a tape 2 in a cassette case 1 formed of two upper and lower plates 1a and 1b.
b, and is wound onto reels 3a and 3b from both ends. Therefore, when the diameter of one winding becomes larger, the diameter of the other winding becomes smaller, and the figure shows a state in which the tape 2 is fully wound around the reel 3b on the supply side. A feature of the cassette is that by not providing flanges on the reels 3a and 3b, the distance between the centers of the reels 3a and 3b is narrowed and the cassette is compact. The tape 2 is now wound in stages around 3b. Therefore, in order to prevent the tape 2 from coming into direct contact with the inner wall surface of the case 1 and causing friction, a gap is created between the reels 3a and 3b and the upper and lower wall surfaces of the case 1, and the tape is made of Teflon or paper. By inserting sheets 5a and 5b called retainers, respectively, the reels 3a and 3
b is held in the middle of case 1.

Inside the case 1, in addition to the tape 2 and reels 3a and 3b, guide rollers 6a and 6b, a pressure pad 7, etc. are housed.
A pair of capstan shaft insertion holes 8a and 8b, positioning pin insertion holes 9a, 9b, 9c and 9d, a pair of pinch roller insertion holes 10a and 10b, reel shaft insertion holes 11a and 11b, and a magnetic head insertion hole 12 are drilled. There is. Incidentally, 3a' and 3b' are engagement claws protruding from the inner peripheral surfaces of the reels 3a and 3b at equal intervals of 60 degrees.

On the other hand, a cassette tape recorder includes a pair of reel shafts 20a and 20b, a capstan shaft 21,
Equipped with a pinch roller 23, a magnetic head 24, etc.
When the cassette is installed, the reel shafts 20a and 2
0b enters the cassette through the reel shaft insertion holes 11a and 11b and engages with the reels 3a and 3b in the rotational direction, and the capstan shaft 21 enters the capstan shaft insertion hole 8a. When the play state is set, the pinch roller 23 enters the cassette through the pinch roller insertion hole 10a and inserts the capstan shaft 2.
The tape 2 is sandwiched between the tape 2 and the capstan shaft 21, and the tape 2 is run at a constant speed in cooperation with a capstan shaft 21 rotating at a constant speed. Further, the magnetic head 24 enters the cassette through the magnetic head insertion hole 12, sandwiches the tape 2 between it and the pressure pad 7, and reproduces the contents of the tape 2 running at a constant speed.

In the playing state as described above, the reel shaft 20a
The reel shaft 20b functions as a tape winder and is rotationally driven by a drive source (not shown), whereas the reel shaft 20b
serves as a tape supply, and although it is not driven by a drive source, it is designed to give a constant back tension to the tape 2.

A conventional example of this supply side reel shaft 20b will be described in detail. In FIGS. 5 and 6, C is a chassis of a cassette tape recorder, and an upright shaft _20b1 is vertically installed in this chassis. Upright shaft 20
A reel shaft main body 20b ₂ having a regular hexagonal cross section is rotatably supported on b ₁ , and on the outer periphery of the shaft main body 20b ₂ , reel shafts 20b ₂ are slidable in the axial direction of the shaft main body 20b 2 and are engaged with each other in the rotational direction. The cylindrical hub _20b3 is fitted so as to fit. The cylindrical hub 20b ₃ is biased in one direction by a spring 20b ₄ compressed between it and the shaft body 20b ₂ , and is kept in the illustrated state by a presser member 20b ₅ fitted onto the shaft body 20b ₂ . is maintained. As described above, the shaft main body 20b ₂ , the cylindrical hub 20b ₃ , the spring 20b ₄ , and the holding member 20b ₅ are made into a unit, and the upright shaft 20b 5 is fixed so as not to come off from the upright shaft 20b ₁ .
It is held in the state shown in the figure by a stopper _20b6 attached to the tip of _b1 . The leaf spring 20b ₇ compressed between the collar of the upright shaft 20b ₁ and the shaft body 20b ₂ is
This is to give back tension to the tape 2 by creating a certain amount of friction between the reel shaft unit and the upright shaft _20b1 . The reel shaft 20b having the above-mentioned configuration is such that when the cassette is installed, even if the reel claw 3b' of the cassette rides on the outer circumferential claw 20b' ₃ of the cylindrical hub 20b ₃ , the cylindrical hub 20b ₃ can escape. . However, if this is not necessary, as shown in Figure 7,
A shaft body 20b ₂ with a pawl 20b' ₂ directly provided on the outer periphery is rotatably supported on the upright shaft 20b ₁ , and the leaf spring 2
It is also possible to simply configure it so that friction occurs at _0b7 .

Now, suppose that when the cassette tape recorder having the above-described structure is in a playing state, vertical vibrations as indicated by the arrows in FIG. 4 are applied. When the frequency of vibration is extremely low, around 1Hz, reels 3a and 3b
moves up and down with case 1 and chassis C,
When the frequency increases, the reels 3a and 3b become stationary, and only the case 1 moves up and down together with the chassis C. As a result, the upper and lower walls of the case 1 violently collide with the reels 3a and 3b from above and below. When such a situation occurs, the tape 2 will expand and contract between the point a where it is held between the capstan shaft 21 and the pinch roller 23 and the point b at the winding end on the reel 3b.

By the way, the tape 2 between the points a and b resonates at a resonance frequency ₀ determined by the spring constant of the tape 2 and the moment of inertia of the tape wound on the reel 3b. Now, 2-3 usually added to tape 2
When we calculated ₀ for the back tension of g, we found that ₀ = 30-40Hz.

When the cassette tape recorder is in the playing state, the claw 3b' of the reel 3b on the supply side engages with the claw _20b'3 of the reel shaft 20b, as shown in FIG. 8a, and rotates the reel shaft 20b in the direction of the arrow. However, when the above-mentioned resonance occurs in the tape 2, the rotation of the reel 3b stops due to the elongation of the tape 2 (Fig. 8b), and the subsequent contraction causes the reel 3b to stop rotating. It rotates rapidly and rotates the reel shaft 20b with a large force (8th
Figure c). For this reason, the reel shaft 20b and the reel 3b
A repulsive force acts between them, and together with the further elongation of the tape 2, the two claws 3b' and _20b'3 finally come to separate as shown in FIG. 8d. Once such a situation occurs, both nails 3b' and 20
Collisions and repulsions occur repeatedly between b' and ₃ , resulting in so-called jitter. As a result, the speed at which the tape 2 moves on the surface of the magnetic head 24 fluctuates, and it has been found that this causes large wow at around 40 Hz.

The present invention has been developed in view of the above-mentioned points, and its purpose is to provide a cassette tape recorder that improves sound quality by preventing large wah from occurring even when vertical vibrations are applied. There is a particular thing.

To this end, the present invention configures at least the reel shaft on the tape supply side to include a shaft body and a cylindrical hub fitted to the outer periphery of the shaft body via a viscoelastic member,
A pawl that engages with a reel of a cassette is formed on the outer periphery of the cylindrical hub, and rotation of the cylindrical hub in the tape supply direction rotates the shaft body via the viscoelastic member. Collisions and repulsions occurring between the supply reel shaft and the cassette reel are buffered by the viscoelastic member, damping the resonance of the tape, thereby suppressing wow.

Embodiments of the present invention will be described below with reference to FIGS. 9 to 21, in which the same or corresponding parts as in FIGS. 3 to 8 are given the same reference numerals.

9 and 10 show a reel shaft 20b on the tape supply side in a one-way cassette tape recorder. A viscoelastic member 30 consisting of a rubber tube made of plain rubber, butyl rubber, etc. as shown in FIG. 11 is elastically attached to the outer periphery of the shaft body _20b2 having a regular hexagonal cross section. When the rubber tube is attached to the shaft body 20b ₂ , it follows the shape of the shaft body 20b2, and its outer shape is transformed into a regular hexagon. _Fitted onto the outer periphery of the viscoelastic member 30 is a cylindrical hub 20b 3 having a claw 20b' ₃ on the outer periphery that engages with the claw 3b' of the reel 3b of the cassette. In this fitting, the cylindrical hub 20b ₃ and the shaft body 20b ₂ are engaged in the rotational direction via the viscoelastic member 30 and rotate together, but the cylindrical hub 20b ₃ is connected to the shaft body 20b ₂ . It is designed so that it can slide freely in its axial direction. Note that the rubber tube shown in FIG. 11b has a large number of holes 30 so that the viscoelastic member 30 is distorted by a weaker force.
A is pierced.

When using the reel shaft 20b configured as described above, the pawl 3b' of the reel 3b of the cassette is attached to the cylindrical hub 2.
Even if it collides with the claw _20b'3 of _0b3 , the impact at that time is buffered by the deformation of the viscoelastic member 30.
The repulsive force generated between the reel 3b and the reel shaft 20b is weakened, and as shown in FIG.
This makes it possible to prevent a situation in which b' and 20b' ₃ become separated from each other. For this reason, the resonance of the tape 2 becomes small, and as shown in FIGS. 12 and 13, which were measured for the embodiment shown in FIGS.
As can be seen from the wah characteristics shown in the figure, conventionally at around 40Hz, it was 1% before auditory correction, and after auditory correction.
The occurrence of wah exceeding 0.2% has disappeared.

FIGS. 14 and 15 show a reel shaft 20b that is applied to a so-called two-way cassette tape recorder that can play in two directions.
In this case, the reel shaft is used not only as a tape supply side but also as a tape take-up side.
A configuration for this purpose is added to the reel shaft 20b.

That is, in the example of FIG. 14, the spring 20
Felts 31 and 32 pressed together by b ₄
The shaft body 20b ₂
A pulley 33 connected to the pulley 33 is added, and a gear 34 rotatably driven by a drive source (not shown) can be selectively engaged with a gear 33a on the outer periphery of the pulley 33.

In the example shown in FIG. 15, a flat motor 35 is rotated when the reel shaft 20b is used on the tape winding side.
is fixed to the chassis C, and a reel shaft unit is fixed to the rotating shaft 35a of this motor 35. In this case, when the reel shaft 20b is used on the tape supply side, the motor 35 is not driven to rotate. Note that the spring 36 attached to the lower end of the rotation shaft 35a is used to generate friction for giving back tension to the tape 2.

In the reel shafts 20b shown in FIGS. 9, 14, and 15 described above, the cylindrical hub 20b ₃ is slidable in the axial direction of the shaft body 20b ₂ , but the function of the reel shaft itself is Lucky doesn't have to be like this. Therefore, as shown in FIG. 16, a stepped portion _20b'2 is provided on the shaft body _20b2 ,
The cylindrical hub 20b ₃ may be sandwiched between the stepped portion 20b' ₂ and the holding member 20b ₅ . In this case, there is no equivalent to spring _20b4 .

17 to 21 show still other embodiments, and in the reel shaft 20b in FIG. 17, the shaft body 20
b ₂ is made to have an equilateral triangular cross section, and there are connections between every other vertex of the regular hexagonal center hole 37 of the cylindrical hub _{20b 3 fitted} on the outer periphery of the shaft body 20b 2 and each surface of the shaft body 20b ₂ . A round bar-shaped viscoelastic member 30' is interposed between them. In this configuration, a leaf spring 20b ₇ for giving back tension to the tape 2, a spring 20
With the friction caused by b ₄ or 36, the shaft body 20b ₂ and the cylindrical hub 20b ₃ rotate in one direction without directly contacting each other, but when this reel shaft is used on the tape winding side, The shaft body 20b ₂ comes into direct contact with the inner wall of the center hole 37 of the cylindrical hub 20b ₃ to rotate the cylindrical hub 20b ₃ . The viscoelastic member 30' is made of plain rubber, butyl rubber, etc.
The shape shown in the figure can also be used.

In the reel shaft 20b in FIG. 19, the shaft body 20b ₂
is made to have a circular cross section, and on its outer periphery, protrusions 38a and recesses 38b are formed every other at equal intervals of 60 degrees, while the center hole 37 of the cylindrical hub _20b3 is made circular, and a 60 degree groove is formed on its inner periphery. Recesses 37a are formed at equal intervals. A viscoelastic member 30'' is interposed between each recess 38b of the shaft body 20b ₂ and the corresponding recess 37a of the cylindrical hub 20b ₃ , and the cylindrical hub 20b ₃ is attached to the outer periphery of the shaft body 20b ₂ . are mated. In this state,
The protrusion 38a of the shaft body _20b2 faces into the recess 37a, but the protrusion 38a faces into the recess 37a during tape feeding.
The rotation of the cylindrical hub 20b ₃ is transmitted to the shaft body 20b ₂ via the viscoelastic member 30'' without directly contacting the wall 7a.However, when the reel shaft is used on the tape winding side, the protrusion 38a directly abuts against the wall of the recess 37a to rotate the cylindrical hub _20b3 .

In the reel shaft 20b in FIGS. 20 and 21,
The shaft body 20b ₂ and the cylindrical hub 20b ₃ are key-fitted, and the cylindrical hub 20 is fitted into the key part of the shaft body 20b ₂ .
When b ₃ rotates in the tape supply direction, the cylindrical hub 20
A viscoelastic member 30 is embedded in the portion where b ₃ hits. Therefore, when supplying the tape, the cylindrical hub 20b ₃
Along with the rotation, the shaft body 20b ₂ is rotated via the viscoelastic member 30.

As described above, the present invention includes a pair of reel shafts rotatably provided on the chassis, and at least the reel shaft on the tape supply side is fitted to the shaft body and the outer periphery of the shaft body via a viscoelastic member. a cylindrical hub, and a pawl that engages with a reel of a cassette is formed on the outer periphery of the cylindrical hub, and rotation of the cylindrical hub in the tape supply direction causes the shaft body to move through the viscoelastic member. I'm trying to rotate it.

Therefore, even if vertical vibration is applied during play on a cassette tape recorder and the tape inside the cassette resonates, the collision between the reel of the cassette and the pawl of the cylindrical hub is prevented by the viscoelasticity of the viscoelastic member. Because there is almost no repulsion between them, the resonance of the tape within the cassette is minimized, preventing the occurrence of the large wah that previously occurred, and improving sound quality. A cassette tape recorder is obtained.

[Brief explanation of drawings]

Figures 1 and 2 are graphs showing the wah characteristics of a conventional cassette-type tape recorder before and after auditory correction, and Figure 3 is a plan view of the cassette-type tape recorder in play mode with one side of the cassette case removed. Figures 4 and 4 are cross-sectional views taken along the - line in Figure 3, and Figures 5 to 7 are cross-sectional views showing conventional supply-side reel shafts. In particular, Figure 6 is a cross-sectional view taken along the - line in Figure 5. The sectional views in FIGS. 8a to 8d are simplified diagrams for explaining the problems that occur when the reel shafts shown in FIGS. 5 to 7 are used, and FIG. FIG. 10 is a sectional view taken along the - line in FIG. 9, FIGS. 11 a and b are perspective views of a portion of FIG. 9, and FIGS. Figures 14 to 16 are graphs showing the wah characteristics before and after auditory correction, which were measured by applying vertical vibration to a cassette tape recorder using the reel shaft shown in Figures 1 and 10, respectively. 9, FIG. 17 is a sectional view corresponding to FIG. 10 of another embodiment, FIG. 18 is a perspective view showing a partial modification of FIG. 17, and FIGS. 19 and 20. The figure is a sectional view corresponding to FIG. 10 of another embodiment, and FIG. 21 is a perspective view of a portion of FIG. 20. 3b... Reel, 3b'... Claw, 20b... Reel shaft, 20b ₂ ... Shaft body, 20b 3... Cylindrical hub, 20b' _{3 ...} Claw, 30, 30', 30'', 30
...Viscoelastic member.

Claims (1)

[Scope of utility model registration request] In an automobile cassette-type tape recorder having a pair of reel shafts rotatably provided on a chassis, at least the reel shaft on the tape supply side is connected via a shaft body and a viscoelastic member having an elastic force on the outer periphery of the shaft body. a cylindrical hub that is fitted with the cassette reel; and a pawl formed on the outer periphery of the cylindrical hub so as to engage with a cassette reel. A cassette-type tape recorder for an automobile, characterized in that the main body is rotated by the viscoelastic member, and resonance of the tape at frequencies lower than 100 Hz caused by vibrations of the automobile is attenuated.