JPH09224297A - Diaphragm for acoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve circumferential bending strength, to prevent deformation at the time of big input and to decrease acoustic reproduction distortion by providing circumferential ribs on a diaphragm between tangential edges. SOLUTION: On a diaphragm 2, plural tangential edges (ribs) 2a are formed while being projected by bending the diaphragm 2 so that a cross section orthogonal with a tangential direction can be inversely V-shaped along the tangential direction from a circle B at the fitting part of a voice coil 3 in the inside area rather than a fitting part 2c with a frame 4. These edges 2a can be elongated and contracted orthogonally to the edges 2a and the function of edges at an ordinary speaker unit is provided. Besides, the prescribed number of ribs 2b, which are formed between the adjacent edges 2a and have the cross section similar to the edges 2a, are provided equally in the circumferential direction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a diaphragm of an acoustic transducer.

[0002]

2. Description of the Related Art As an example of a diaphragm of a conventional acoustic transducer,
The speaker unit 10 shown in FIG. 6 will be described. The speaker unit 10 has a diameter of 3 cm and is used for a small portable radio or the like. The speaker unit 10 extends on the diaphragm 11 in the tangential direction of the circle B in the voice coil mounting portion, and has a cross section orthogonal to the tangential direction. A plurality of ribs called tangential edges 11a of a protrusion formed in a substantially inverted V shape are provided. Therefore, the diaphragm 11 is allowed to expand and contract to some extent in the tangential edge 11a in the direction orthogonal to the tangential direction, and the tangential edge 11a expands and contracts according to the amplitude of the voice coil, It secures the amplitude amount of the diaphragm, and conventionally plays a role of an edge formed on the periphery of the diaphragm and responsible for the amplitude amount of the diaphragm accompanying vibration.

In the speaker unit 10 having the tangential edge 11a, since the function of the edge is incorporated in the diaphragm itself, the number of parts can be reduced, and the tangential edge 11a allows the material of the edge portion to be formed. Since it is possible to improve the strength while keeping it thin and lower the minimum resonance frequency,
Theoretically, acoustic characteristics with little distortion can be obtained in a wide frequency range.

[0004]

However, in the above-mentioned conventional configuration, although the rigidity of the diaphragm in the radial direction is improved, the tangential edge 11a forms the diaphragm in an inverted V shape (even if it is a V shape). (Almost the same effect can be obtained)
Since the ridge is formed by bending the ridge, the bending strength in the direction orthogonal to the tangential edge 11a decreases. In other words, due to the above strength decrease,
Due to increase in amplitude due to large input, increase in amplitude due to resonance when there is a resonance frequency in a higher range, etc.
There is a problem in that bending occurs in the direction orthogonal to the tangential edge 11a, and reproduction distortion occurs in the frequency range. The above is an example of the acoustic transducer that converts an electric signal into sound, but conversely, the same can be said for an acoustic transducer that converts sound into an electric signal, for example, a microphone unit. That is, when the sound pressure level of the sound to be converted into an electric signal is high, the bending of the tangential edge causes a distortion in the output electric signal.

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to make use of the characteristics of the tangential edge and to prevent the deformation of the diaphragm when the input / output sound pressure level is high. Another object of the present invention is to provide a diaphragm for an acoustic transducer, which has less distortion and good acoustic characteristics.

[0006]

In order to solve the above-mentioned problems, a diaphragm of an acoustic transducer according to a first aspect of the present invention is the diaphragm of an acoustic transducer in which a tangential edge is formed. It is characterized in that circumferential ribs are provided on the vibration plate between the mechanical edges. Further, in order to solve the above problems, in the diaphragm of the acoustic transducer according to the invention of claim 2, in addition to the configuration of claim 1, the ribs are arranged in an odd number at equal intervals in the circumferential direction. It is characterized by being. Further, in order to solve the above-mentioned problems, in the diaphragm of the acoustic transducer according to the invention of claim 3, in addition to the configuration of claim 1, the ribs are arranged in a prime number at equal intervals in the circumferential direction. It is characterized by being.

With the above construction, the bending strength of the diaphragm in the circumferential direction is improved, the diaphragm is prevented from being deformed when the sound pressure level at the time of input / output is large, and the distortion and sound of reproduced sound are prevented. It is possible to reduce distortion when converting into an electric signal. At this time, the number of the above-mentioned ribs is an odd number with a small divisor, and further, it is a prime number, and evenly arranged on the diaphragm, so that resonance of the standing wave does not occur in the divisor, so the maximum amplitude at resonance Can be reduced, and the above distortion can be reduced.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a diaphragm of an acoustic transducer of the present invention will be described below with reference to FIGS. 1 to 5. In the present embodiment,
A speaker unit will be taken as an example of the acoustic transducer.

First, the structure of the speaker unit according to the present embodiment will be described. The speaker unit 1 shown in FIG. 2 is a speaker unit 1 having a diameter of 3 cm used for a portable radio or the like, and its structure is such that a magnet 6 and a center are provided in a central portion of a support yoke 5 having a circular shape and a substantially U-shaped cross section. The pole 7 is the outer peripheral surface of the center pole 7 and the supporting yoke 5.
While being fixed so that an air gap is formed between the diaphragm 4 and the inner peripheral surface thereof, the vibration plate 2 is attached to the frame 4 provided on the open end side of the support yoke 5 at the attachment portion 2c, and vibration is generated. A voice coil 3 is fixed to the center of the plate 2 so as to be loosely fitted in the air gap.

As shown in FIG. 1, on the diaphragm 2, in the region inside the mounting portion 2c for the frame 4, the tangential line from the circle B of the mounting portion of the voice coil 3 described above along the tangential direction. A plurality of, here, 24 ribs called tangential edges 2a are formed by bending the diaphragm 2 so that the cross section orthogonal to the direction becomes an inverted V shape, and are formed on the ridges. This tangential edge 2a ...
Can be expanded and contracted in a direction orthogonal to the tangential edge 2a, and functions as an edge in a normal speaker unit. Further, the tangential edge 2 is formed between the adjacent tangential edges 2a.
A total of eight ribs 2b having the same cross section as a are provided in the circumferential direction.

Between the tangential edges 2a and 2a formed with the ribs 2b, the strength against bending in the direction intersecting with the direction in which the tangential edge 2a is formed is improved, and the vibration plate 2 is deformed as the amplitude increases. Is less likely to occur, the increase in amplitude due to the divided vibration in the non-axial symmetric direction is suppressed, and the distortion of the acoustic characteristics can be reduced.

For example, FIG. 7 shows the acoustic characteristics of the conventional speaker unit 10 shown in FIG. 6 in which only 24 tangential edges 11a are formed.
1 shows the acoustic characteristics of the speaker unit shown in FIG. 1 of the present embodiment, in which the same 24 tangential edges 2a as described above are provided with eight ribs 2b in total.

Comparing the two, in the case of only the tangential edge, as can be seen from FIG. 7, 5000 Hz to 6000
Although the decrease in sound pressure level in the frequency range of Hz is remarkable, if a rib in the circumferential direction is provided between the tangential edges,
As can be seen from FIG. 3, the sound pressure level slightly decreases in the frequency range of 3000 Hz to 4000 Hz, which is the above 5000 Hz to 6000.
The sound pressure level in the frequency range of Hz has been substantially improved to almost the same level as other frequency ranges, and it can be said that the acoustic characteristics are improved as a whole. That is, it is considered that by forming the rib 2b as described above, the rigidity of the diaphragm having the tangential edge is improved, and as a result, the acoustic characteristics are improved.

FIG. 5 shows the acoustic characteristics of the speaker unit 1'using the diaphragm 2'shown in FIG. The diaphragm 2'is manufactured so that the number of the tangential edges 2a is 21 so that the number of the ribs 2b becomes 7. In this case as well,
The sound pressure level in the frequency range of 5000 Hz to 6000 Hz is improved, and unlike the speaker unit 1 using the diaphragm 2, the speaker unit 1'has a substantially flat sound pressure level in the reproducible frequency range. Good acoustic characteristics are obtained.

Consider the reason why the acoustic characteristics of the diaphragms of FIGS. 1 and 3 differ from each other. In the portion where the ribs 2b ... Are formed, the strength and the weight are changed at regular intervals with respect to the portion where the ribs 2b are not formed. Therefore, depending on the elastic force of the diaphragm and the like, it is easy to generate non-axially divided vibration at a specific frequency. In particular, the number 8 has a plurality of divisors such as 4 or 2, and therefore, when the number of ribs 2b such as 8 is provided, each of the divisors also has a non-symmetrical divided vibration. As a result, the amplitude at the time of resonance becomes large, and on the contrary, there is a high possibility that the sound pressure level at the resonance frequency will decrease and the reproduction distortion will occur. Also in the case of the diaphragm 2 of the speaker unit 1 shown in FIG. 1, it is considered that the sound pressure level is slightly decreased in the frequency range of 3000 Hz to 4000 Hz due to the occurrence of the resonance. .

From this, it can be inferred that if the number of ribs is odd, the number of divisors is small and the split resonance in the above-mentioned non-axial symmetric mode is hard to occur, so that good acoustic characteristics are obtained. . Although the number 7 is also a prime number, it can be said that a prime number is more preferable than an odd number in the sense that having a divisor causes resonance in the divisor as described above.

In the above-described embodiment, the speaker unit that converts an electric signal into sound is described as an example of the acoustic converter, but the same can be said for a headphone unit and the like. On the other hand, when applied to a microphone unit that converts sound into an electric signal, since the diaphragm does not deform even if the sound pressure level is high, the sound input is converted into a more faithful electric signal. Good recording characteristics.

[0018]

As described above, the diaphragm of the acoustic transducer according to the invention of claim 1 is a diaphragm of an acoustic transducer having tangential edges formed on the diaphragm between the tangential edges. This is a configuration in which circumferential ribs are provided. Therefore, the bending strength in the circumferential direction of the diaphragm is improved, deformation at the time of large input is prevented, and the acoustic reproduction distortion can be reduced.

In addition to the structure of claim 1, the diaphragm of the acoustic transducer according to the invention of claim 2 has a structure in which the above-mentioned ribs are odd numbered and arranged at equal intervals. The diaphragm of the acoustic transducer according to the present invention has a configuration in which, in addition to the configuration of claim 1, the ribs are prime numbers and are arranged at equal intervals. Therefore, in the structure of claim 1, by setting the number of the ribs to an odd number or a prime number with a small divisor, resonance of the standing wave in the divisor is less likely to occur, and thus the maximum amplitude at resonance is reduced. It is also possible to obtain the effect that the reproduction distortion can be reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of a diaphragm of an acoustic transducer according to the present invention, and is a plan view of a speaker unit using the diaphragm.

FIG. 2 is a sectional view of the speaker unit shown in FIG. 1, taken along the line AA.

FIG. 3 is a graph showing acoustic characteristics of the speaker unit shown in FIG.

FIG. 4 shows another embodiment of the diaphragm of the acoustic transducer according to the present invention, and is a plan view of a speaker unit using the diaphragm.

5 is a graph showing acoustic characteristics of the speaker unit shown in FIG.

FIG. 6 is a plan view showing a conventional speaker unit.

FIG. 7 is a graph showing acoustic characteristics of the speaker unit shown in FIG.

[Explanation of symbols]

 1 speaker unit 1'speaker unit 2 diaphragm 2a tangential edge 2b rib 2'diaphragm 3 voice coil 4 frame 5 support yoke 6 magnet 7 center pole

Claims (3)

[Claims] 1. A vibrating plate of an acoustic transducer in which tangential edges are formed, wherein a rib in a circumferential direction is provided on the vibrating plate between the tangential edges. Board. 2. The diaphragm for an acoustic transducer according to claim 1, wherein an odd number of the ribs are arranged at equal intervals in the circumferential direction. 3. The diaphragm for an acoustic transducer according to claim 1, wherein the ribs are arranged in a prime number at equal intervals in the circumferential direction.