JPH067710B2 - Speaker - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a speaker, and in particular, a small amplitude of a vibration source such as a voice coil is amplified by a mechanical amplifying means such as a lever to a diaphragm. It relates to a speaker that transmits.

2. Description of the Related Art In recent years, audio equipment has been significantly miniaturized due to the progress of semiconductor technology and the advent of high-performance small circuit components. Speaker systems are becoming smaller regardless of home needs or in-vehicle systems, but there is a problem with the acoustic characteristics in the low frequency range.

That is, the on-axis sound pressure (P _r ) and the amplitude (X) of the speaker are given by the following equations.

Where ρ ₀ is the density of air, ω is the vibration angular frequency, a is the effective radius of the diaphragm, r is the distance between the speaker and the microphone, V is the speed of the diaphragm, X is the amplitude of the diaphragm, and A is the force coefficient. E is the signal of the input voltage, the electrical resistance of R _E is a speaker, M _s is the vibration system mass of the loudspeaker, M _a load mass of air, Q ₀ is the sharpness of the resonance, f ₀ is the lowest resonant frequency, f is the frequency Is.

Therefore, the efficiency decreases as the effective radius of the diaphragm decreases. Further, according to the equation (2), the amplitude of the diaphragm is inversely proportional to the square of the frequency above f ₀ , and therefore becomes large in the low sound range.
However, if the voice coil winding width is reduced in order to improve efficiency, the amplitude range of the voice coil is narrowed, so that a distortion component is generated in the low frequency range. As a driving method capable of large amplitude, there is a speaker using a long voice coil, but the utilization factor of the voice coil loop length is deteriorated and the efficiency cannot be improved. Therefore, in order to improve efficiency and reduce the distortion rate, it is necessary to amplify the amplitude of a small voice coil and transmit it to the diaphragm.
As shown in Japanese Patent Publication No. 9826, there is one using a lever.

Hereinafter, the above-described conventional speaker will be described with reference to the drawings.

FIG. 4 shows a cross section of a conventional speaker using an amplitude amplification mechanism. In FIG. 4, 1 is a pot yoke, 2
Is a magnet, 3 is a pole piece, and a pot yoke 1
The pole piece 3 holds the magnet 2 and forms an annular magnetic gap 4. Reference numeral 5 is a support table fixed to the upper surface of the pole piece 3, and has a bearing portion of a fulcrum a so that the lever 6 can rotate. In the magnetic gap 4, there is a voice coil bobbin 8 around which a voice coil 7 that reciprocates in response to a signal input is wound. The upper end of the voice coil bobbin 8 is rotatable to a distance l ₁ from a fulcrum a of the lever 6. It is held by the lever 6 at various connecting points b. Further, from the fulcrum a to l ₂ (where l ₂ > l
There is also a pivotable coupling point c at the distance ₁ ) and a reinforcing ring 9 is attached. Reference numeral 10 denotes a substantially frustoconical diaphragm which is fixed to the reinforcing ring 9 at the bottom. A damper for supporting the voice coil bobbin 8 and an edge for supporting the diaphragm 10 are not shown.

The operation of the conventional speaker configured as described above will be described below.

When a signal current flows through the voice coil 7 in the magnetic gap 4 formed by the pot yoke 1, the magnet 2 and the pole piece 3, the voice coil 7 and the voice coil bobbin 8
The connection point b of is changed by x. Therefore, the lever 6 rotates about the rotatable fulcrum a provided on the support 5. At this time, the displacement X of the connecting point c of the lever 6 is And the displacement is amplified by l ₂ / l ₁ times. Therefore, the reinforcing ring 9 having the coupling point c and the fixed diaphragm 10 are amplified by l ₂ / l ₁ times with respect to the displacement of the voice coil 7.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above configuration, since the lever rotates about the fulcrum a, the coupling points b and c are l ₁ (1-cos θ) and l ₂ (1- Since it moves only by cos θ), bending force is applied to the voice coil bobbin and the reinforcing ring, and the voice coil comes into contact with the pole piece or pot yoke and produces abnormal noise, which is not suitable as an amplitude amplification mechanism. It was

In view of the above problems, the present invention provides a speaker capable of efficiently reproducing a low sound range and high fidelity.

Means for Solving the Problems In order to achieve this object, a speaker of the present invention has a regular polygonal central support part in which a voice coil bobbin is inserted and fixed in a central hole, and each central support part has an outer peripheral portion. A plurality of bendable and extensible first rectangular cylinders connected through the first bent portion, a connecting portion on the inner peripheral side of the first rectangular cylinder, and a part of two sides extending from the connecting portion. And a second quadrangular tubular body that can be bent and stretched as a common portion.
Is formed inside the rectangular cylindrical body, and the outer peripheral portion of the first rectangular cylindrical body is connected to the outer peripheral support through the second bent portion, and the outer peripheral end of the outer peripheral support and the diaphragm. Are connected by a drive rod, and the outer peripheral portion of the second rectangular tubular body is fixed via a third bent portion.

Action With this configuration, when the driving force of the voice coil is applied to the inner peripheral portion of the first rectangular cylindrical body, a rotational movement occurs around the outer peripheral portion of the fixed second rectangular cylindrical body, and by the lever principle, The displacement of the outer peripheral portion of the first rectangular cylinder is enlarged, and the displacement of the vibration plate fixed to the drive rod is also enlarged as compared with the displacement of the voice coil, so that the reproduction in the low range is particularly good. is there. Further, at this time, since both the inner peripheral portion and the outer peripheral portion of the first rectangular tubular body can be moved only in the vertical direction, the voice coil and the vibration plate due to the rotational movement of the lever as shown in the above-mentioned conventional example are formed. The displacement of the joint portion of the lever is eliminated, and the gap rubbing of the voice coil can be prevented. Further, since the first rectangular cylinder and the second rectangular cylinder can also serve as a damper that holds the position of the voice coil, there is an advantage that the damper can be simplified and the configuration of the speaker can be simplified. It is a thing.

Embodiment One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of a speaker in an embodiment of the present invention, FIG. 2 is a plan view of a further main part thereof, and FIG. 3 is a schematic sectional view showing its operation.

In FIG. 1, FIG. 2, and FIG. 3, 11 is a frame, 1
Reference numeral 2 is a diaphragm, 13 is an edge having an inner peripheral edge adhered to the outer peripheral edge of the diaphragm 12 and the outer peripheral edge is fixed to the frame 11, and 14 is a voice coil 14a having a lower end inserted in a gap (not shown) of a magnetic circuit. A voice coil bobbin wound around a central support portion 15 having the voice coil bobbin 14 inserted and fixed in a central hole and having a bent portion a at each outer periphery, and 16 connecting an inner peripheral portion to the bent portion a and an outer peripheral portion 1 is a first rectangular cylinder connected to b, 17 is an outer peripheral support part whose inner periphery is connected to the bent part b, 1
8 is a drive rod whose lower end is fixed to the outer peripheral support 17 and upper end is fixed to the vibration plate 12, 19 is a fixed base whose lower end is fixed to the bottom of the frame 11, and 20 is the inner peripheral side of the first rectangular tubular body 16. Of 2
This is a second rectangular tubular body in which some of the sides are common and the outer peripheral edge is fixed to the fixed base 19 via the bent portion c. In FIG. 1, the hatching of the first and second quadrangular cylinders 16 and 20 is omitted. Further, hatching is omitted in FIG.

The operation of the speaker configured as above will be described below.

First, when a reproduction signal current is applied to the voice coil 14a of the voice coil bobbin 14 whose lower end is inserted in the magnetic gap, a driving force is generated by Fleming's left-hand rule, and the voice coil bobbin 14 vibrates vertically. This vibration is transmitted to the central support portion 15 and the bent portion a, and the first rectangular cylindrical body 1
The inner peripheral end of 6 also vibrates vertically. At that time, with the outer peripheral end portion of the second quadrangular cylinder 20 as the center, the first quadrangular cylinder 16 and the second quadrangular cylinder 20 reciprocally rotate while bending and stretching so that their diagonal lengths change. First square cylinder 1
An outer peripheral support portion 17 connected to the outer peripheral end of 6 via a bent portion b.
Vibrates up and down, and the vibrating plate 12 vibrates up and down through the drive rod 18 fixed to the vibrating plate to generate sound.

Here, the movements of the first rectangular cylinder 16 and the second rectangular cylinder in the operation in the above configuration will be described in more detail with reference to FIG.

In FIG. 3, the solid line shows the stationary state and the broken line shows the displaced state. When the voice coil bobbin 14 is displaced downward by X, the points d, e, f, g of the first rectangular cylinder 16 are deformed to become points d ', e', f ', g', and the second point The points d, i, j, h of the rectangular tubular body 20 are also deformed to become points d ', i', j ', h', and the drive rod 18 is displaced by Y. At this time, since the first rectangular tube body 16 and the second rectangular tube body 20 are always similar in shape, the relationship between the displacement X of the voice coil bobbin and the displacement Y of the drive rod is represented by the following formula according to the lever principle. .

Therefore, the displacement of the vibration plate 12 connected to the drive rod 18 is obtained by subtracting the diagonal length of the second quadrangular cylinder from the diagonal length (dj) of the second quadrangular cylinder 20 and the diagonal length of the first quadrangular cylinder 16. The displacement of the voice coil bobbin 14 is enlarged by the ratio of the one (jf).

As described above, according to the present embodiment, in the speaker provided with the mechanical amplification mechanism that expands the displacement of the diaphragm according to the lever principle, instead of the rod-shaped lever, the bendable and extensible first rectangular tubular body 16 is provided. By using an amplifying mechanism composed of a second quadrangular tubular body 20 in which a part of the two sides on the inner peripheral side of the first quadrangular tubular body 16 are made common and the outer peripheral end is rotatably fixed, As in the operation shown in FIG. 3, the first rectangular tube body 16,
The second quadrangular tubular body 20 holds the parallelogram while bending and stretching, and moves like a pantograph.
The drive rod 18, and the diaphragm 12 do not move laterally,
Since it can move only in the vertical direction, the position of the end of the lever 6 shifts toward the center due to the rotational movement as in the conventional example, a bending force is applied to the voice coil bobbin 8 and the diaphragm 10, and the voice coil 7 moves to the pole piece 3 or. It does not generate abnormal noise when it contacts the pot yoke 1. Furthermore, since the first and second quadrangular cylinders 16 and 20 have a function as a damper that moves while holding the position of the voice coil bobbin 14, the damper can be omitted and the configuration as a speaker is simplified. There is an advantage that can be realized.

In the present embodiment, the four surfaces forming the first rectangular cylinder 16 and the second rectangular cylinder 20 are flat, but by providing reinforcing ribs to these, the rigidity of the surfaces is increased and resonance occurs. Therefore, the acoustic characteristics of the speaker are improved.
Although the diaphragm 12 has a flat plate shape, it may have a cone shape.
The shape is not limited to a circle, but can be changed to a square, triangle, or any other shape depending on the application.

EFFECTS OF THE INVENTION According to the present invention, a first quadrangular tubular body that can be bent and extended instead of a lever and a part of two inner peripheral sides of the first quadrangular tubular body are made common, and an outer peripheral end is rotatably fixed. By using the amplifying mechanism composed of the second rectangular cylinder, the voice coil bobbin and the diaphragm can be vibrated only in the vertical direction,
Further, in accordance with the lever principle, the displacement of the voice coil bobbin is amplified and transmitted to the diaphragm, which enables good bass reproduction.

Further, the amplification mechanism of the present invention also has a function of supporting the voice coil bobbin at the center position, and since it plays the role of a damper in the conventional electrodynamic speaker, the speaker structure can be simplified. Therefore, an excellent speaker can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a speaker according to an embodiment of the present invention, FIG. 2 is a plan view of a further main part thereof, FIG. 3 is a schematic sectional view showing its operation, and FIG. FIG. 11 ... frame, 12 ... vibration plate, 13 ... edge,
15 ... central support part, 16 ... first square tubular body, 17 ...
... peripheral support, 18 ... driving rod, 19 ... fixing base, 20
...... Second quadrangular cylinder, a, b, c ...... Bent part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kosaku Murata 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Mitsuru Iejo, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) Reference Bibliography Sho 51-19826 (JP, U)

Claims (1)

[Claims] 1. A regular polygonal center support part in which a voice coil bobbin is inserted and fixed in a central hole, and a plurality of bendable and extendable parts connected to each outer periphery of the center support part via a first bent part. Half of the diagonal length of the first rectangular tubular body, the connecting portion on the inner peripheral side of the first rectangular tubular body, and a part of two sides extending from the connecting portion are used as a common portion. A second quadrangular tubular body having a shorter diagonal length, which is bendable / extendable, and the second quadrangular tubular body is formed inside the first quadrangular tubular body, and the first quadrangular tubular body is formed. Has its outer peripheral portion connected to the outer peripheral support through the second bent portion, the outer peripheral end of this outer peripheral support and the diaphragm are connected by a drive rod, and the outer periphery of the second rectangular tubular body is further connected. A speaker provided with a mechanical amplification mechanism in which a portion is fixed via a third bent portion.