JPS6212300A - Speaker - Google Patents

Abstract

PURPOSE:To reproduce a low frequency range efficiently with high fidelity by joining an end part of a lever with a voice coil rotatably by the 1st driving rod and the other end part with a diaphragm by the 2nd driving rod, and equalizing the ratio of the lengths from the fulcrum of the level to the joint parts nearly to the length ratio of both driving rods. CONSTITUTION:The lever 14 and voice coil 15 are joined together by the 1st driving rod 18 which can be bent and the lever 14 and diaphragm 12 are jointed together by the 2nd driving rod 19 which can be bent at two positions. When the lever 14 rotates and reciprocates to move as shown by arrows (d) and (d'), the lateral position shift of the end part of the lever 14 is absorbed because the bent parts 18a and 18b, and 19a and 19b of the driving rods 18 and 19 are rotatable; and neither the voice oil 15 nor the diaphragm 12 shift laterally and move only vertically, thereby preventing an abnormal sound from being generated. Further, the lever ratio (l2/l1) is equalized to the length ratio (f/e) of the 1st driving rod 18 and the 2nd driving rod 19 to put the displacement of the voice coil 15 and the displacement of the diaphragm 12 in linear relation, thereby eliminating distortion due to the driving system.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the improvement of speakers, and in particular, to amplifying the small amplitude of a vibration source such as a voice coil to a diaphragm using mechanical amplification means such as a lever. It is related to speakers that transmit information.

BACKGROUND OF THE INVENTION In recent years, audio equipment has become significantly smaller due to advances in semiconductor technology and the emergence of high-performance compact circuit components. Speaker systems are also becoming smaller, whether for home needs or car-mounted systems, but there are problems with acoustic characteristics in the bass range.

That is, the axial sound pressure (Pa) and amplitude (X) of the speaker are given by the following equations.

・・・・・・・・・(1) (m)・・・・・・・・・(Note: ρ is the air density, ω is the vibration angular frequency, a is the effective radius of the diaphragm, τ is The distance between the speaker and the microphone, ■ is the speed of the diaphragm, X is the amplitude of the diaphragm, A is the force coefficient, E is the signal input voltage, RE is the electrical resistance of the speaker, Ms is the mass of the speaker's vibration system, and Ma is The air load mass, Qo is the resonance sharpness, fo is the lowest resonance frequency, and f is the frequency.

Therefore, as the effective radius of the diaphragm becomes smaller, efficiency decreases. Furthermore, the amplitude of the diaphragm is inversely proportional to the square of the frequency above h and t0 according to equation (2), so it becomes large in the bass range.

However, if the winding width of the voice coil is made smaller in order to improve efficiency, the amplitude range of the voice coil becomes narrower, resulting in distortion components occurring in the bass range. There is a speaker using a long voice coil as a driving method that allows a large amplitude, but the utilization rate of the voice coil wire length is poor and efficiency cannot be improved. Therefore, in order to improve efficiency and reduce distortion, it is necessary to amplify the amplitude of the small voice coil and transmit it to the diaphragm.
As shown in Japanese Patent No. 826, there was one that used a lever.

The conventional speaker described above will be described below with reference to the drawings.

FIG. 3 shows a cross section of a conventional speaker using an amplitude amplification mechanism. In Figure 3, 1 is the acupoint yoke, 2
is a magnet, 3 is a pole piece, pot yoke 1
and the pole piece 3 sandwich the magnet 2 to form an annular magnetic gap 4.

Reference numeral 5 denotes a support base fixed to the upper surface of the pole piece 3, and has a bearing portion with a fulcrum so that the lever e can rotate. In the magnetic gap 4, there is a voice coil bobbin 8 wound with a voice coil 7 that reciprocates in response to signal input, and its upper end extends from the fulcrum a of the lever 6 to
The coupling point is already held on the lever 6, which can be rotated by a distance of . Furthermore, there is a similarly rotatable connection point C at a distance of 12 (however, 12>11.) from the fulcrum &, and the reinforcing ring 9
is installed. - 1o is a substantially truncated cone-shaped diaphragm fixed to the reinforcing ring 9 at the bottom. Note that the damper supporting the voice coil bobbin 8 and the edge supporting the diaphragm 10 are omitted from the diagram.

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 connecting point S changes by I. Therefore, the lever 6 rotates around a rotatable fulcrum provided on the support base 6. At this time, the displacement X of the connection point C of the lever 6 is given by X=-+@X, and the displacement is amplified 12/11 times. Therefore, the reinforcement ring 9 having the coupling point C and the diaphragm 10 fixed thereto are amplified by l 2/11 times with respect to the displacement of the voice coil 7.

Problems to be Solved by the Invention However, in the above configuration, since the lever rotates around the fulcrum a, there is no connection point.

C is el(1-cosθ), 12(
1-CO8θ), the voice coil bobbin and reinforcement 11Jy□, ge. Ka, 2 Ka. However, it was not suitable as an amplitude amplification mechanism because it had problems such as contacting the ear piece or the pot yoke and generating abnormal noise.

In view of the above-mentioned problems, the present invention provides a speaker that efficiently reproduces bass frequencies with high fidelity.

Means for Solving the Problems In order to achieve this object, the speaker of the present invention has a structure in which the end of the lever and the voice coil, which are rotatably supported around a fulcrum, are rotatable by a first drive rod. and has a mechanical amplification mechanism in which the other end and the diaphragm are joined by a second drive rod, and the length from the fulcrum of the lever to the joint with the first drive rod and the fulcrum The length ratio from the first drive rod to the joint part with the second drive rod is approximately equal to the length ratio of the first drive rod and the second drive rod.

Function: With this configuration, the driving force of the voice coil is sequentially transmitted to the first drive rod, lever, second drive rod, and diaphragm, and due to the lever principle, vibration is reduced compared to the displacement of the voice coil, which is the drive unit. Because the displacement of the plate is greatly expanded (
This results in better bass reproduction (amplified by the ratio of the length from the fulcrum of the lever to the joint with the first drive rod and the length from the fulcrum to the joint with the second drive rod). Furthermore, since the voice coil and the diaphragm are connected to both ends of the lever via drive rods, the position of the joint between the voice coil and the diaphragm and the lever may shift due to the rotational movement of the lever as shown in the conventional example. This can prevent the voice coil gap from being strained.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 shows a sectional view of essential parts of a speaker according to an embodiment of the present invention.

In FIG. 1, 11 is a frame, 12 is a diaphragm, and 13 is a diaphragm.
14 is a lever, 15 is a voice coil whose lower end is inserted into a gap (not shown) in a magnetic circuit; 17 is a damper whose inner peripheral end is fixed to the voice coil 16 and its outer peripheral end to the frame 11; 17 is a support rod whose upper end is fixed to the frame 11, the lever 14 is fixed to the lower end, and has a bendable part 17a; 18 is the upper end with lever 1
4, and its lower end is fixed to the upper end of the voice coil 16, and the bendable portion 18a.

A first drive rod 18b, 19 has an upper end connected to the diaphragm 1.
2, its lower end is fixed to the other end of the lever 14, and has bendable parts 19a and 19b. The support rod 17 and the first and second drive rods 8 and 19 are integrally formed using polyester elastomer (trade name: Hytrel), which is a type of rubber-like polymeric elastic material. The bendable portion is configured as a shape.

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

First, when a reproduction signal is applied to the voice coil 16 inserted into the magnetic gap, a υ force is generated according to Nlemming's left-hand rule, causing the voice coil 16 to vibrate up and down. This vibration
Transmitted from the first drive rod 18 to the lever 14 and the support rod 17
The lever 14 moves in the direction of the arrow d, centering on the bent portion 17a of
Reciprocate in the d/direction. This is further the second drive rod 1
The sound is transmitted to the diaphragm 12 via the diaphragm 9 and generates sound.

Here, the relationship between the length ratio of the lever 14 from the fulcrum and the length ratio of the first drive rod 18 and the second drive rod 19 in the above configuration will be explained. FIG. 2 shows a schematic diagram of the above configuration for explanation. In Fig. 2, 12 is a diaphragm;
14 is the lever, 15 is the voice coil, 0 is the fulcrum to which the lever 14 is fixed to the support rod 17, 11 is the length of the lever 14 from the fulcrum 0 to the part where it is fixed to the first drive rod 18, j
2 is the length from the fulcrum 0 of the lever 14 to the fixed part with the second drive rod 19, e is the length of the first drive rod 18, and f is the second
, Y is the displacement when the voice coil 15 moves in the direction of arrow q, X is the displacement of the diaphragm when the voice coil 16 is displaced Y, and δ1 is the length of the lever 14 and the first drive. The displacement of the fixed part P1 with the rod 18, δ2 is the displacement of the fixed part P2 between the lever 14 and the second drive rod 19. When the lever 14 rotates around the fulcrum 0, the lever 14 moves due to the lever principle. The displacement δ1: of the end P1 is expanded to 12/11 times the lever ratio, and the displacement δ2 of the other end P2
can be given to Here, when the voice coil 15 is displaced upward by Y, Pl is displaced upward by δ1, and the other end P
2 is displaced upward by δ2, and the diaphragm 12 is displaced downward by X. When the lever 14 is displaced, the angle between the first drive rod 18 and the vibration axis of the voice coil 15 is α, and the second drive rod 1
When the angle between 9 and the vibration axis of the diaphragm is β, and the rotation angle of the lever 14 is θ, the following equation holds true.

δ1=Y −e (1−cos a ) −=
-・Ih(3)δ2= ('y”1)δ1
・・・・・・・・・・・・(→δ2=x−f(1−
cO5β) ・・・・・・・・・・・・(6
)β=5io−112(1−cosθ)−−0−0,−
006,-<-r>(3) # (4) # (5)
e (6) e From formula (7). Equation (8) expresses the relationship between the displacement Y of the voice coil 15 and the displacement X of the diaphragm 12, but when the second term on the right side is not 0,
Due to this relationship, linearity deteriorates and distortion occurs. Also, if 12/11 = f/e (the lever ratio and the ratio of the length of the first drive rod 18 and the length of the second drive rod 19 are made equal), then α = β, and the right side of equation (8) The second term becomes 0, and the displacement X of the diaphragm 12 is amplified by the lever ratio C12/11) of the displacement Y of the voice coil 16, and no distortion occurs. Therefore, in this embodiment, the lever ratio (12/11) and the ratio of the lengths of the first and second drive rods (f/e) are made equal.

As described above, according to this embodiment, in a conventional speaker equipped with a mechanical amplification mechanism that uses a lever to amplify the displacement of a diaphragm using the lever principle, the position of one end of the lever shifts toward the center due to rotational movement. Bending force is applied to the voice coil bobbin and the diaphragm, and the voice coil may come into contact with the pole piece or the point yoke, causing abnormal noise. However, according to this embodiment, the lever 14 and the voice coil 16 are connected at two places. Connected by a bendable first drive rod 18, the lever 14
and the diaphragm 12, the second drive rod 1 can be bent at two places.
9, the bent portion 18a of the first drive rod 18 remains intact even when the lever 14 rotates and reciprocates and moves in the directions of arrows d and d/.

18b and the bent portion 19a of the second drive rod 19.

Since the lever 19b is rotatable, the shift in the lateral position of the end of the lever 14 is absorbed, and the voice coil 15° and the diaphragm 12 do not move laterally, but only in the vertical direction, which prevents the above-mentioned abnormalities. This has the advantage of being able to prevent the generation of sound. Furthermore, the lever ratio C12/11) and the first
The ratio of the lengths of the driving rod 18 and the second driving rod 19 (f/
By making e) equal, the displacement of the voice coil 15 and the displacement of the diaphragm 12 are in a linear relationship, which eliminates distortion caused by the drive system.

In this embodiment, the diaphragm 12 is disposed in a direction opposite to the voice coil 15, but the diaphragm 12 may be disposed on the side of the voice coil 16 and the magnetic circuit. In this case, since the drive rod 18 of the tube 1 and the second drive rod 19 can be arranged on the same side, the speaker as a whole can be made thinner.

Further, the shape of the diaphragm 12 is not limited to a flat plate, but may be a cone shape.

Effects of the Invention The present invention has a structure in which the lever and the voice coil are connected by a first drive rod, and the lever and the diaphragm are connected by a second drive rod.
It is possible to absorb horizontal displacement of one end of the lever due to rotational reciprocating motion of the lever, and vibrate the voice coil and diaphragm only in the vertical direction. As a result, no horizontal bending force is applied to the voice coil, eliminating abnormal noise that occurs when the voice coil contacts the magnetic gap, and the displacement of the voice coil is amplified and transmitted to the diaphragm using the lever principle. This allows for good bass reproduction. Furthermore, by making the lever ratio C12/11) and the length ratio (f/e) of the first and second drive rods equal, the displacement of the voice coil and the displacement of the diaphragm are in a linear relationship.The driving force transmission system This makes it possible to realize a speaker with excellent acoustic characteristics and no distortion.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a speaker according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the structure of a speaker according to the same embodiment, and FIG. 3 is a sectional view of a conventional speaker. 14... Lever, 17... Support rod, 1
8...First drive rod, 19...Second drive rod, 17a. 18a, 1sb, 19a, 19b---
−・−Bendable part. Name of agent: Patent attorney Toshio Nakao and 1 other person4
Figure 3

Claims (1)

[Claims] The end of the lever, which is rotatably supported around a fulcrum, and the voice coil are rotatably joined by a first drive rod, and the other end and the diaphragm are rotatably supported by a second drive rod. and the ratio of the length from the fulcrum of the lever to the joint with the first drive rod and the length from the fulcrum to the joint with the second drive rod is such that A speaker equipped with a mechanical amplification mechanism characterized in that the ratio of the lengths of the drive rods is approximately equal to the length ratio of the drive rods.