JPH0229549Y2 - - 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, which is almost no problem, whereas wah at around 40Hz is still 0.2.
% or more, and it was found that this deteriorated 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 Teflon area is replaced by 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 on 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 a reel shaft main body 20b ₂ is rotatably supported on the outer periphery of the shaft main body 20b ₂ . 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 integrated into a unit, and the upright shaft 20b 5} is fixed to the upright shaft 20b ₁ so that they do not come off 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 constant 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 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 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 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, so that 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.

Therefore, in the present invention, at least the reel shaft on the tape supply side has a spring that supports the reel from below, and this spring has an elastic force that is approximately balanced with the weight of the reel when the remaining amount of tape is at its maximum. The spring prevents the reel from violently colliding with the bottom wall inside the cassette case when vertical vibration is applied to the reel, damping the vertical movement of the reel inside the cassette case and reducing tape resonance. Collision and repulsion between the reel and the claw on the reel shaft are weakened to keep the wow low.

Embodiments of the present invention will be described below with reference to FIGS. 9 to 18, in which the same or corresponding parts as in FIGS. 3 to 8 are given the same reference numerals.

9 to 11 show the reel shaft 20b on the tape supply side when the cassette type tape recorder is one-way type.

In the reel shaft 20b shown in FIGS. 9 to 11, a collar _20b''3 on _which the engaging pawl 3b' of the reel 3b of the cassette rests is integrally formed on the _lower side of the pawl 20b'3 of the cylindrical hub 20b3. The reel 3b of the attached cassette is supported from below by a spring _20b4 via a cylindrical hub _20b3 , and the reel 3b is held in the cassette at an intermediate position between the upper and lower cases 1a and 1b. However, the spring _20b4 of this reel shaft 20b has an elastic force so as to substantially 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 30 will be created between the two.

In the above-described embodiment, the elastic force of the spring 20b ₄ is selected to have a specific strength, but a strong spring 20b ₄ is used as before, and instead, a leaf spring 20b ₇ is used that satisfies the above conditions. It can also be made into something. In this case, when the cassette is installed, the entire reel shaft unit sinks, creating a gap between the stopper _20b6 and the holding member _20b5 .

In either case, the reel 3b of the cassette is supported from below by the spring _20b4 or the leaf spring _20b7 , so even if vertical vibration is applied, the reel 3b will collide with the lower inner wall of the cassette case 1. This eliminates this problem, and the vertical movement of the reel 3b is reduced by half. Therefore, the resonance of the tape 2 within the cassette case is reduced, and collision and repulsion in the rotational direction between the claw 3b' of the reel 3b and the claw 20b' ₃ of the cylindrical hub 20b ₃ hardly occur. That is, the jitter shown in FIG. 8 is less likely to 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, the howe of more than 0.2% disappears, and the overall characteristics become far less than 1% or 0.2%.

FIG. 15 shows a preferred modification, in which the cylindrical hub 2
A recess 31 having a tapered surface on one side is formed in the collar 20b'' ₃ adjacent to the pawl 20b' ₃ of the reel 0b ₃ , and the reel's engaging pawl 3b' is dropped into this recess 31 to attach the reel 3.
b makes it difficult to move in the rotational direction with respect to the cylindrical hub _20b3 . This prevents the claw 3b' of the reel 3b from separating from the claw 20b' ₃ of the cylindrical hub 20b ₃ even if the tape 2 resonates.

FIGS. 16 and 17 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.

That is, in the embodiment shown in FIG. ₁₅ , the shaft main body 2 is
A pulley 34 connected to the _pulley 34 is added, and a gear 35 rotated by a drive source (not shown) can be selectively engaged with a gear 34a on the outer periphery of the pulley 34.

In the example of FIG. 17, a flat motor 36 is rotated when the reel shaft 20b is used on the tape winding side.
is fixed to the chassis C, and the rotation shaft 36a of this motor 36 is fixedly connected to the reel shaft unit. In this case, when the reel shaft 20b is used on the tape supply side, the motor 36 is not driven. Note that the spring 3 attached to the lower end of the rotating shaft 36a
Reference numeral 7 is for generating friction to give back tension to the tape 2.

In the reel shafts 20b of FIGS. 9, 16, and 17 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, does not have to be like this. Therefore, as shown in FIG. 18, a member 38 that is a combination of a presser member and a cylindrical hub is fitted onto the shaft body _20b2 , and this member 38 is engaged with the pawl 3b' of the reel 3b. A claw 38' is provided. The spring _20b4 is compressed between the pawl 38' and the shaft body _20b2 , and when the cassette is installed, the pawl 3b' of the reel 3b presses against the spring 20b.
b ₄ It is designed to sit on top. Note that the member 38 is tapered to prevent the spring 20b ₄ from shifting to one side.

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 has a spring that supports the reel from below, and the spring supports the reel from below. It 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-type 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.
Therefore, collision and repulsion between the reel and the claw of the reel shaft due to tape resonance are less likely to occur, and the speed at which the tape passes through the magnetic head surface is kept almost constant, resulting in a cassette type with less wow and improved sound quality. A tape recorder is obtained. Furthermore, it is possible to obtain a cassette-type tape recorder which prevents the occurrence of wow at the beginning of tape winding, where wow is most likely to occur.

[Brief explanation of the drawing]

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 tape supply side reel shafts. In particular, 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 arise when using the reel shafts shown in FIGS. 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. 12 is a sectional view of the side reel shaft. The figure is a cross-sectional view showing the state in which the cassette is attached to the reel shaft in Figure 9, and Figures 13 and 14 show the wah characteristics before and after auditory correction, measured with vertical vibration applied in the condition shown in Figure 12. The graphs shown respectively, FIG. 15 is a side view showing partial deformation of the reel shaft in FIGS. 9 to 12, and
6 to 18 are sectional views corresponding to FIG. 9 of other embodiments. 3b...Reel, 3b'...Claw, 20b...Reel shaft, _20b'3 , 38'...Claw, _20b4 ...Spring, _20b7 ...Plate spring (elastic member).

Claims (1)

[Scope of utility model registration request] A pair of reel shafts each having a claw that engages with the reel of the cassette in the rotational direction, at least the reel shaft on the tape supply side has a spring that supports the reel from below, and the spring has a spring that supports the reel when the remaining amount of tape on the reel is at its maximum. An in-vehicle cassette-type tape recorder that has an elastic force that substantially balances the weight of the vehicle.