JPH01251898A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To reduce the distortion of a sound by making 3 sets of mutually crossing reinforced textile yarns as a weaving yarn and forming with a fiber reinforced plastic of which resin is reinforced by a seamless three axis woven fabric. CONSTITUTION:Three axis woven fabric 4 making the reinforced textile yarn as the weaving yarn is plain-woven with mutually crossing 3 sets (3 pieces) of weaving yarn 1 (warp), 2 (weft) and 3 (warp) at the angle of 60 degree respec tively. Thus, since three sets of mutually crossing reinforced textile yarns are used for the weaving yarn as the so-called reinforcing material of the resin and the seamless three axis fabric is used, comparing with a conventional dia phragm using a two axis fabric, the unevenness of a weaving yarn distribution in the peripheral direction of a cone or the like and the unevenness of an elastic modulus are made smaller, a bell-shaped vibration is hardly generated and the distortion of the sound is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a speaker imaging board made of fiber reinforced plastic (FRP) using a triaxial fabric as a so-called reinforcing material.

2. Description of the Related Art A speaker imaging board made of FRP is well known. For example, in Japanese Patent Publication No. 59-47520, there are two sets of
A cone-shaped diaphragm is described that is made of a resin-reinforced so-called biaxial fabric, which is extremely common as a fabric, and uses carbon fiber threads that are orthogonal to each other as yarns. However, since this conventional diaphragm uses a biaxial fabric, the arrangement of the weaving threads is not symmetrical with respect to the axis of the cone, and the weaving threads are arranged in two directions: the generatrix direction and the circumferential direction of the cone. Because there are alternating parts extending in the same direction and parts extending ±45 degrees away from those directions, the change in the elastic modulus in the circumferential direction of the cone is large, and it is generally bell-shaped. There is a problem in that a resonant vibration mode called vibration tends to appear, resulting in large sound distortion.

On the other hand, Japanese Unexamined Patent Publication No. 61-49592 describes a cone-shaped diaphragm made of FRP in which a resin is reinforced with a spiral fabric using carbon fiber threads.

However, in spiral fabrics, the weaving threads extend in two directions, the circumferential direction and the radial direction, and the arrangement of the weaving threads is symmetrical with respect to the axis of the cone, resulting in the above-mentioned bell-shaped vibration problem. doesn't happen. However, on the other hand, there are problems as explained below.

In other words, in the above-mentioned swirl fabric, the yarns in the radial direction form a radial pattern, so the yarn density is denser on the inside (neck side) of the diaphragm and coarser on the outside (edge side). Therefore, the difference in elastic modulus in the generatrix direction of the cone is very large.

For example, if we consider a diaphragm with an inner diameter of 3 cm and an outer diameter of 15 cm, the inner portion is:
If it is set to about 50 volume %, which is a very normal value for FRP, it will be about 10 volume % in the outer part, and the elastic modulus will be proportionally lower. On the other hand, set the outer part to 50
If the amount is about % by volume, the adjacent weaving yarns will become so dense that they overlap each other in the inner part, making it difficult to form. Even if it could be molded, the inner part would be thicker and the weight of the diaphragm would increase, reducing efficiency. Naturally, such inconvenience becomes more noticeable as the diameter becomes larger, since the difference between the inner diameter and the outer diameter becomes larger.

Problems to be Solved by the Invention The purpose of the present invention is to solve the above-mentioned problems of conventional diaphragms, and to provide a diaphragm with less unevenness in weaving yarn distribution and even less unevenness in elastic modulus, less distortion of sound, and excellent acoustic characteristics. To provide diaphragms for speakers.

Means for Solving the Problems In order to achieve the above-mentioned objects, the present invention uses three sets of reinforcing fiber threads that intersect with each other as one woven thread, and strengthens the resin with a seamless 3#A woven fabric. This product features a speaker diaphragm made of fiber-reinforced plastic. The diaphragm of this invention has a cone shape, a dome shape, etc.
A city can come in many different shapes.

To explain this invention in detail, in this invention, three sets of mutually crossing reinforcing fiber threads are used as the so-called reinforcing material of the resin, and a seamless triaxial fabric [
Triaxial cloth (also called Doweave) is used.

The reinforcing fiber yarn is made of multifilament of high strength, high modulus fiber such as carbon fiber, glass fiber, polyaramid fiber, alumina fiber, etc.

, depending on the type of fiber, the single yarn diameter is about 4 to 40#m,
Preferably about 4 to 20 μm, the number of single threads is 500 to 600
The number is about 0, preferably about 500 to 3000.

Usually, the three sets of yarns are of the same fineness and thickness. However, when reinforcing fiber yarns are used in combination with different reinforcing fibers, such as carbon fibers and polyaramid fibers, advantages arise, such as the ability to easily balance elastic modulus and internal loss.

A triaxial fabric using such reinforcing fiber yarns as weaving yarns has three sets (three yarns) of weaving yarns 1 (warp yarn), 2 (weft yarn), and 3 (warp yarn), as shown by reference numeral 4 in FIG. are arranged in a flat structure, intersecting each other at an angle of 60'. However, the intersecting angle of the weaving threads does not necessarily have to be 60'.

In other words, in the case of a cone-shaped or dome-shaped imaging plate, 60
The angle is preferably 50', 50', or 80' in the case of an ellipsoidal cone or a semi-elliptic sphere. In that case, the part 80' is used in the short axis direction.

3! The III fabric 4 also has weaving yarns (warp yarns>18.1b and
Weaving yarn (weft>28.2b and weaving yarn (warp) 3a, 3
It is also possible to use a flat weave with b and b as one set.

The triaxial woven fabric and its manufacturing method as shown in Figures 2 and 3 are described, for example, in "Overseas Textile Technology Literature Collection", Volume 23, No. 11 (November 1973, published by Japan Society of Textile Machinery Society ) and US Patent No. 3,446,251.

The above-mentioned triaxial fabric has a crimp rate of yarn of 10% or less,
The content is preferably 5% or less. Here, chestnut]/
The customer C (%) is calculated using the formula: C-[(L-Lo)/Lo] x 100, where L: Length of yarn measured when stretched straight and without crimps; o: With crimps. If the crimp rate is 10% or less, the stress concentration at the bent part of the weaving yarn will be small, and the decrease in elastic modulus will be small.

The resin that forms the so-called matrix of the diaphragm is
Thermosetting resins such as epoxy resins, unsaturated polyester resins, polyimide resins, and phenolic resins, as well as thermosetting resins such as polyamide resins, polybutylene terephthalate resins, polyether ether ketone resins, polypropylene resins, and poly-4-methylpentene-1 resins. It is a plastic resin. When the above-mentioned thermosetting resin is mixed with 10 to 20% by weight of a flexibility imparting agent such as polyethylene glycol, polypropylene glycol, polysulfide, etc., vibration damping properties are improved. In addition, 20 to 20% of polyisobutylene resin is added to poly-4-methylpentene-1 resin.
When 0% by weight is used, not only the vibration damping properties but also the specific elastic modulus of the diaphragm are improved.

The diaphragm of this invention usually has only one 3f111! However, if a plurality of triaxial fabrics are stacked on top of each other so that the directions of the weaving threads of adjacent triaxial fabrics are slightly shifted, pseudo-isotropy can be further improved. Further, it is also possible to use the above-mentioned triaxial fabric and a normal biaxial fabric, mat, etc. in a superimposed manner.

The diaphragm of the present invention can be molded using a well-known molding method or the like.

That is, for example, the above-mentioned 3eX! A prepreg made by impregnating woven fabric with a thermosetting resin is placed on a female mold having a desired cone shape, a male mold is roughly placed on top of the female mold, and pressure is applied.
It can be molded by heating to harden the resin. Also, instead of using prepreg, we use so-called raw 3! which is not impregnated with thermosetting resin! Tl1l
A prepreg may be formed by placing the fabric on a female mold and applying a thermosetting resin containing a curing agent. When the resin is a thermoplastic resin, the diaphragm can be made by stamping molding the prepreg. The same applies to other shapes such as a dome shape.

The embodiment drawings show a cone-shaped diaphragm, which is made of FRP made by reinforcing resin 5 with triaxial fabric 4 shown in FIG. The diaphragm of this embodiment uses 3EI
Since the intersecting angles of the three sets of yarns in the Il fabric are all 60', the same yarn arrangement is obtained when rotated by 60 degrees around the cone axis. That is, it has a rotational symmetry of 60'. By the way, since a conventional diaphragm using a two-glaze fabric can only obtain 90' rotational symmetry, the diaphragm of this embodiment has improved quasi-isotropy, and the difference in the elastic modulus in the circumferential direction is improved. is lowered accordingly, making it difficult for bell-shaped vibrations to occur. Also, even if this happens, the 4-fold rotational symmetry of 90° becomes 6-fold rotational symmetry of 60', so the natural frequency increases by that amount, and it is not a problem in terms of characteristics as a speaker imaging plate. .

[Effects of the Invention] [This invention] The disturbance board is a so-called reinforcing material of resin.
Because we use 3 pairs of reinforcing fiber yarns that intersect with each other as weaving threads and a seamless 3@lI fabric, it is easier to reduce the circumferential direction of cones, etc. compared to conventional biaxial fabrics. The unevenness in the weaving yarn distribution and, as a result, the unevenness in the elastic modulus of the material becomes very small, making it difficult to generate bell-shaped vibrations and reducing sound distortion. Since the unevenness of the weaving yarn distribution is reduced, the morphological distortion is also reduced. Furthermore, it is possible to prevent a decrease in efficiency due to an increase in weight, which is a disadvantage of using spiral fabrics.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing a speaker imaging plate according to an embodiment of the present invention, and FIGS. 2 and 3 are schematic plan views showing different embodiments of triaxial fabrics used in the present invention. It is a diagram. 1.1a, 1b: Woven yarn 2.2a, 2b: Woven yarn 3.3a, 3b: Woven yarn 4: Triaxial fabric 5: Resin

Claims (1)

[Claims] A speaker diaphragm made of fiber-reinforced plastic made of three sets of reinforcing fiber threads that intersect with each other and reinforced with seamless triaxial fabric.