JPH0229550Y2 - - 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 wow is like, we measured the wah by applying 1G vertical vibration to an existing cassette tape recorder while changing the frequency, and found the wah (RMS) characteristics shown in Figure 1. was gotten. 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)
is less than 0.2%, a value that is hardly a problem, whereas wah at around 40Hz still remains.
It was found that 0.2% or more was present, and this caused poor 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. The 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 can be narrowed and the reels can be compactly assembled. Tape 2 is now wound in stages. For this reason, the tape 2 is
A gap is created between the reels 3a and 3b and the upper and lower wall surfaces of the case 1 so that the reels 3a and 3b do not come into direct contact with the inner wall surface of the case 1 and cause friction. By inserting the reels 3a and 3b, respectively, the reels 3a and 3b are held in the middle of the 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 held in 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 claws 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 together with case 1 and chassis C, but
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 resonant frequency f 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 f ₀ was calculated for the case of a back tension of g, it was found that f ₀ =30-40 Hz.

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 reel 3b rapidly rotates due to the subsequent contraction. This causes the reel shaft 20b to rotate with a large force (FIG. 8c). Therefore, the reel shaft 20b and the reel 3
A repulsive force acts between the tape 2 and the tape 2, and together with the further elongation of the tape 2, the two claws 3b' and _20b'3 finally come to be separated 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. Therefore, tape 2
It was found that the speed at which the magnetic head moves on the surface of the magnetic head 24 fluctuates, and this causes a large wah at around 40 Hz. Furthermore, at the beginning of winding of the tape 2 (that is, when the remaining amount of the tape 2 is at its maximum), the degree of imbalance between the remaining amounts of tape on both reels is at its maximum, and thus wow is most likely to occur.

This invention was made in view of the above points,
The purpose is to provide a cassette type tape recorder which improves the sound quality by preventing the occurrence of large wah noises even when vertical vibrations are applied. Another object of the present invention is to provide a cassette-type tape recorder which prevents wow from occurring at the beginning of tape winding, where wow is most likely to occur.

To this end, the present invention has at least a friction member in which the reel shaft on the tape supply side makes frictional contact with the reel of the cassette, and an elastic member that supports the reel from below via this friction member. The elastic member prevents the reel from violently colliding with the bottom wall of the cassette case when vertical vibrations are applied to the cassette, and prevents the reel from colliding violently with the bottom wall of the cassette case. Attenuates the vertical movement of the reel and reduces the resonance of the tape, and the frictional resistance of the friction member weakens the collision and repulsion that occurs between the reel and the pawl of the reel shaft due to the resonance of the tape, thereby eliminating wow. I'm keeping it low.

Embodiments of the present invention will be described below with reference to FIGS. 9 to 17, in which the same or corresponding parts as in FIGS. 3 to 8 are given the same reference numerals.

9 to 12 show the reel shaft 20b on the tape supply side when the cassette type tape recorder is one-way type.

The reel shaft 20b shown in FIGS. 9 to 11 has an engagement groove 30 formed around the circumference on the lower side of the pawl 20b' ₃ of the cylindrical hub 20b ₃ . The reel shaft is almost the same in structure as the reel shaft shown in FIG. 3, except that an annular friction member 31 made of is attached. However, in this reel shaft 20b, the claw 3b' of the reel 3b of the attached cassette rides on the friction member 31, and the reel _3b is moved by the spring _20b4 via the friction member 31 and the cylindrical hub 20b3. Supporting the reel 3b from below, the upper and lower cases 1a and 1 are placed inside the cassette 1.
It is designed to be held at an intermediate position of b. In addition, the spring 20b ₄ has an elastic force so as to approximately balance the weight when the remaining amount of tape on the reel 3b is at its maximum.
It is selected to be 10-20g. Therefore, when the cassette is attached, as shown in FIG. 12, the upper end surface of the cylindrical hub _20b3 is slightly separated from the presser member _20b5 , and there is a gap between the cylindrical hub _20b3 and the presser member _20b5 . A gap 33 is created between the two. In addition, 34 is claw 2
This slit was created due to the mold used to form _0b'3 .

In the above embodiment, the elastic force of the spring _20b4 was selected to have a specific strength;
It is also possible to use a strong material for b ₄ as before, and instead use a leaf spring 20b ₇ that satisfies the above-mentioned conditions. In this case, when cassette 1 is installed,
The entire reel shaft unit begins to sink, and a gap is created between the stopper _20b6 and the holding member _20b5 .

In either case, the reel 3b of the cassette 1 is supported from below by an elastic member consisting of the spring _20b4 or the leaf spring _20b7 via the friction member 31, so that even if vertical vibrations are applied, the cassette case 1 The reel 3b no longer collides with the lower inner wall of the reel 3b, and the vertical movement of the reel 3b is halved. Along with this, the resonance of the tape 2 is also attenuated, but even if the tape 2 resonates, the reel 3
b and the friction member 31 are in contact and a large contact resistance is working between them, making it difficult for the reel 3b to move in the rotational direction relative to the cylindrical hub _20b3 , and the claw 3b of the reel 3b ′ and the claw 20b′ ₃ of the cylindrical hub 20b ₃ and repulsion hardly occur.
That is, jitter as shown in FIG. 8 does not occur, the speed at which the tape 2 moves on the surface of the magnetic head 24 is kept constant, and wow is improved.

As can be seen from the wah characteristic graphs in FIGS. 13 and 14 measured for the embodiments shown in FIGS. 9 to 12, this improvement is 1% before auditory correction, which conventionally occurred at around 40 Hz. After auditory correction, wah of more than 0.2% is eliminated, and the overall characteristics are much less than 1% or 0.2%.

FIGS. 15 and 16 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 winding side.
A configuration for this purpose is added to the reel shaft.

That is, in the embodiment shown in FIG. ₁₅ , the shaft main body 20 is
A pulley 37 connected to _b2 is added, and a gear 38 rotated by a drive source (not shown) can be selectively engaged with a gear 37a on the outer periphery of this pulley 37.

In the example shown in FIG. 16, a flat motor 39 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 39a of this motor 39. In this case, when the reel shaft 20b is used on the tape supply side, the motor 39 is not driven. Note that the spring 4 attached to the lower end of the rotating shaft 39a
0 is for producing friction to give back tension to the tape 2.

In the reel shafts 20b of FIGS. 9, 15, and 16 described above, the cylindrical hub 20b ₃ is slidable in the axial direction of the shaft body 20b ₂ , but as a function of the reel shaft itself, It is not necessary for it to be like this. Therefore, as shown in FIG. 17, a member 4 that integrates a presser member and a cylindrical hub
1 is provided with a pawl 41' that engages with the reel 3a, and the friction member 31' is connected to the member 41 via a spring _20b4 .
and the shaft body _20b2 .

As described above, the present invention includes a pair of reel shafts having claws that engage with the reels of a cassette in the rotational direction, and at least the reel shaft on the tape supply side includes a friction member that makes frictional contact with the reels of the cassette, and It has an elastic member that supports the reel from below via a member, and the elastic member has an elastic force that is approximately balanced with the weight of the reel when the remaining amount of tape is at its maximum.

Therefore, even if vertical vibrations are applied during play on a cassette tape recorder, the reel will not collide with the lower inner wall of the cassette case, and the vertical movement of the reel within the cassette will be reduced, so the resonance of the tape will be reduced. It won't become something big. In addition, because the reel is in frictional contact with the friction member, it is difficult for the reel to move in the rotational direction with respect to the reel shaft, so even if the tape resonates, there will be a collision between the reel and the claw on the reel shaft. , repulsion is less likely to occur, and resonance at large tape amplitudes is suppressed.
A cassette type tape recorder is obtained in which the speed at which the tape passes through the magnetic head surface is kept almost constant, and the wow is small and the sound quality is improved. Furthermore, a cassette type tape recorder can be obtained in which wow is prevented from occurring at the beginning of tape winding, where wow is most likely to occur.

[Brief explanation of drawings]

Figures 1 and 2 are graphs showing the wah characteristics of a conventional cassette tape recorder before and after auditory correction. Figure 3 is a plan view of the cassette tape recorder in play mode with one side of the cassette case removed. Figure 4 is a cross-sectional view taken along the - line in Figure 3, Figures 5 to 7 are cross-sectional views showing the conventional tape supply side reel shaft, and especially Figure 6 is a cross-sectional view taken along the - line in Figure 5. FIG. 8 is a simplified diagram for explaining the problems that occur when using the reel shafts shown in FIGS. A sectional view of the side reel shaft, FIG. 10 is a sectional view taken along the - line in FIG. 9, FIG. 11 is a plan view showing the state in which the cassette is attached to the reel shaft in FIG. 9 together with a part of the reel, and FIG. The figure is a sectional view showing the state in which the cassette is installed in Fig. 9, and Figs.
Graphs showing the wah characteristics before and after auditory correction were measured by applying vertical vibration to a cassette tape recorder using a reel shaft as shown in FIGS. 15 to 11, and FIGS. FIG. 9 is a sectional view corresponding to FIG. 9; 3b... Reel, 3b'... Claw, 20b... Reel shaft, 20b' ₃ ... Claw, 20b ₄ ... Spring (elastic member), 20b ₇ ... Leaf spring (elastic member), 3
1,31'...Friction member.

Claims (1)

[Scope of utility model registration request] The apparatus includes a pair of reel shafts having claws that engage with the reels of the cassette in the rotational direction, and includes a friction member in which at least the reel shaft on the tape supply side makes frictional contact with the reels of the cassette, and the reel is moved from below through the friction member. 1. An in-vehicle cassette type tape recorder comprising: a supporting elastic member, the elastic member having an elastic force that substantially balances the weight of the reel when the remaining amount of tape is at its maximum.