JPH08140183A - Diaphragm for acoustic device - Google Patents

Abstract

PURPOSE: To prevent the occurrence of a dip of relative sensitivity in the frequency band in a specific range by providing many radial narrow grooves in a subdome part so that their inner ends reach the boundary part between a main dome part and the sundome part. CONSTITUTION: With respect to a diaphragm A, many radially extended narrow grooves 4... provided in a subdome part 2 are extended across a boundary part 5, and their inner ends 41 reach an inner peripheral edge 51 of the boundary part 5. The adhesive by which a voice coil is adhered to the boundary part 5 is used only for adhesion of the voice coil, and its quantity is neither too much nor too less. The diaphragm A constituted in this manner has flat relative sensitivity in 4 to 8kHz frequency band and is free from a dip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm used in an acoustic device such as a dynamic type small speaker or a microphone.

[0002]

2. Description of the Related Art This type of diaphragm is manufactured by molding an ultrathin polymer film.
As can be inferred by
It has a circular shape as a whole, and integrally has a sub-dome portion 2 that bulges in the same direction as the main dome portion 1 around the main dome portion 1, and the outer peripheral portion of the sub-dome portion 2 is an edge frame 3 made of metal. The sub-dome portion 2 is fixed and is provided with a large number of thin grooves 4 radially at equal intervals. In such a diaphragm A, the boundary portion 5 between the main dome portion 1 and the sub dome portion 2 has an annular shape as shown in FIG.
Is formed as a narrow flat portion, and the voice coil 6 is held on the boundary portion 5 by adhesion as shown in FIG.

In the conventional diaphragm A, as shown in FIG.
And as shown in FIG. 5, all the inner ends 41 of the large number of narrow grooves 4 ...
Was located in the immediate vicinity of the boundary 5 and on the outer side thereof.

By the way, a large number of the fine grooves 4 ... Helps to reinforce the diaphragm A, and the linearity of vibration is higher than that of the diaphragm A having the fine grooves 4 ... Which does not have the fine grooves 4. It has been found that the sound quality is improved and the acoustic characteristics are also preferable. Here, the linearity of vibration means that the range of vibration with a uniform amplitude becomes large. When the amplitude is large, the entire diaphragm vibrates with a uniform amplitude, but when the frequency is large, the desired amplitude is obtained. There are some parts that do not vibrate.

However, when the frequency characteristic of the sensitivity in the diaphragm A in which the voice coil 6 is simply fixed to the boundary portion 5 by adhesion is examined, the frequency characteristic of 4 to 8 kHz is shown as shown by the broken line in FIG. 6 showing the same characteristic. A dip occurs in the relative sensitivity in the frequency band. It is considered that this is because a phenomenon occurs in which the portion near the boundary portion 5 in the subdome portion 2 shown in FIG. 5 and the boundary portion 5 are integrated and do not vibrate.

Therefore, as one of the conventional measures for eliminating the dip in the relative sensitivity occurring in the frequency band of 4 to 8 kHz, as shown in FIG.
It has been performed that the bending rigidity of the portion is increased by applying the adhesive 72 so as to straddle the boundary portion 5 and the sub dome portion 2 which hold the above. Conventionally, a large amount of the adhesive 71 used when the voice coil 6 is bonded to the boundary 5 is used, and the surplus thereof is used as the adhesive 72 straddling the boundary 5 and the sub dome 2. Alternatively, the voice coil 6 is attached to the boundary portion 5 with the adhesive 71.
After adhering with the adhesive, the adhesive 72 is separately applied across the boundary portion 5 and the subdome portion 2.

[0007]

However, the surplus of the adhesive 71 used for adhering the voice coil 6 is used as the boundary portion 5.
And the sub-dome portion 2 as the adhesive agent 72, or when the adhesive agent 72 is separately applied over the boundary portion 5 and the sub-dome element 2, the adhesive agent 72 as in the conventional case. However, taking measures to reinforce the portion extending over the boundary portion 5 and the sub-dome portion 2 has problems in workability and uniformity of characteristic improvement effect. That is, when a portion extending over the boundary portion 5 and the sub dome portion 2 is reinforced with the adhesive 72, the amount of the adhesive 72 is the most appropriate amount for keeping the vibration characteristics optimal, and If there is an excess or deficiency of the amount of the agent 72, it becomes impossible to uniformly improve the vibration characteristics. On the other hand, it is difficult for even a skilled person to apply the optimum amount of the adhesive 72.

The present invention has been made in view of the above problems and circumstances, and the reinforcing action of a large number of fine grooves provided in the subdome portion is also applied to a portion extending between the boundary portion and the subdome portion. Reinforcing that part by taking measures that extend to make the part near the boundary of the subdome part and the boundary part vibrate integrally, and dip the relative sensitivity in the frequency band of 4 to 8 kHz. An object of the present invention is to provide a diaphragm of an acoustic device that does not occur.

[0009]

According to a first aspect of the present invention, there is provided a diaphragm for an audio apparatus, wherein a sub-dome portion is continuously provided around a main dome portion, and the sub-dome portion is provided with a large number of thin grooves in a radial shape. In the diaphragm of the device, the inner end of the narrow groove reaches the boundary between the main dome portion and the sub dome portion.

In the diaphragm of the acoustic device according to the second aspect of the present invention, the boundary portion is formed flat and the narrow groove crosses the boundary portion.

[0011]

According to the first aspect of the invention, the inner end of the narrow groove for reinforcing the sub-dome portion reaches the boundary between the main dome portion and the sub-dome portion. The straddling portion is reinforced by the narrow groove, and the portion of the sub-dome portion near the boundary and the boundary easily vibrate together.

According to the second aspect of the invention, since the narrow groove crosses the boundary portion, not only the portion extending over the boundary portion and the subdome portion, but also the boundary portion is reinforced by the narrow groove. become. For this reason, the effect that the portion close to the boundary and the boundary in the sub-dome portion easily vibrate together is further promoted.

[0013]

1 is a plan view of a diaphragm A according to an embodiment of the present invention, FIG. 2 is an end view when the diaphragm A is cut at a central portion, and FIG. 3 is taken along line III-III of FIG. It is the schematic sectional drawing which expanded the part. In these figures, 1 is a main dome portion, 2 is a sub dome portion, 3 is an edge frame, 5 is a boundary portion between the main dome portion 1 and the sub dome portion 2, and 6 is a voice coil. Since it is the same as that described with reference to FIGS. 4 and 5, detailed description thereof will be omitted.

In this diaphragm A, as shown in FIGS. 1 and 3, a large number of radially extending thin grooves 4 provided in the sub-dome portion 2 extend across the boundary portion 5, and The inner end 41 reaches the inner peripheral edge 51 of the boundary portion 5. Further, the adhesive 71 for adhering the voice coil 6 to the boundary portion 5 is used only for adhering the voice coil 6, and there is no excess or deficiency in the amount.

The sensitivity frequency characteristic of the diaphragm A having the above-mentioned structure was examined as an invention product. As a result, the relative frequency characteristic in the frequency band of 4 to 8 kHz is shown as shown by the solid line in FIG. Sensitivity is flattened so that the dip (represented by the broken line) does not occur unlike the conventional case.

The same investigation was also conducted when the inner end of the narrow groove 4 was located at a position reaching the boundary portion 5 (a state where the narrow groove 4 did not cross the boundary portion 5). The relative sensitivity was flattened in the frequency band of 4 to 8 kHz.

In this embodiment, the inner ends 41 ... Of all of the plurality of fine grooves 4 ...
Although all the fine grooves 4 ... Cross the boundary 5, the relative sensitivity in the frequency band of 4 to 8 kHz can be flattened by making every one or two narrow grooves 4 ... I know that I can do it. That is, in order to achieve the object of the present invention, the inner end 41 of all or a part of the large number of the fine grooves 4 ... Is made to reach the boundary portion 5 or the boundary portion 5 is crossed. Good.

In the diaphragm A of the illustrated example, a large number of narrow grooves 4 ... Are arranged radially extending tangentially to an imaginary circle having a diameter smaller than that of the boundary portion 5. The sub-dome portions 2 may be arranged in a radial pattern extending in the radial direction.

The boundary 5 does not necessarily have to be flat as in the embodiment, and may have, for example, a valley shape.

[0020]

According to the first and second aspects of the present invention, the portion extending over the boundary portion and the subdome portion and the reinforcement of the boundary portion are formed by extending the narrow groove provided in the subdome portion inward. This is achieved by making the inner end of the groove reach the boundary or by allowing the narrow groove to cross the boundary.Therefore, when molding the narrow groove that is performed at the same time when molding the main dome or sub dome, The above-mentioned points and boundaries are reinforced without performing the step of. Therefore, there is no need to perform the work of applying an adhesive to the part that straddles the boundary part and the subdome part as in the past, and in addition, there is no variation in the characteristic improvement effect, and the acoustic characteristics are homogenized There is an effect that it can be highly advanced.

[Brief description of drawings]

FIG. 1 is a plan view of a diaphragm according to an exemplary embodiment of the present invention.

FIG. 2 is an end view when the diaphragm is cut at the center.

3 is an enlarged schematic cross-sectional view of a portion along line III-III in FIG.

FIG. 4 is a plan view of a conventional diaphragm.

FIG. 5 is an enlarged schematic sectional view of a main part of a conventional diaphragm.

FIG. 6 is a graph showing the sensitivity frequency characteristics of the invention product and the conventional product.

[Explanation of symbols]

 A diaphragm 1 main dome portion 2 sub dome portion 4 narrow groove 5 boundary portion 41 inner end of narrow groove

Claims (2)

[Claims] 1. A diaphragm of an acoustic device, wherein a sub-dome portion is continuously provided around a main dome portion, and a plurality of fine grooves are radially provided in the sub-dome portion, wherein an inner end of the fine groove is the main dome portion. A diaphragm of an acoustic device, which reaches a boundary with the subdome portion. 2. The diaphragm for an acoustic device according to claim 1, wherein the boundary between the main dome portion and the sub dome portion is formed flat, and the narrow groove crosses the boundary portion.