JPH1175293A - Electroacoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce unnecessary resonance at an outer peripheral part even when projection parts are vibrated in one body and to suppress sound distortion by increasing the thickness of the outer peripheral part of a diaphragm or providing members having high rigidity thereupon, and thus making the rigidity larger for those of projection parts. SOLUTION: The diaphragm 70 consists of peak parts 7a1 to 7a7, a plane part 7b, and the outer peripheral part 70c. This outer peripheral part 70c is made thicker than the peak parts 7a1 to 7a7 and plane part 7b so as to increase rigidity. Thus, the diaphragm 70 has its outer peripheral part 70c made larger in rigidity by changing the materials of the outer peripheral part 70c or varying the thickness. An entire-surface drive thin speaker unit having constitution like this can reduce unnecessary resonance (split vibration) generated at the outer peripheral 70c when the respective peak parts 7a1 to 7a7 have uniform entire-surface vibration in the front-rear direction to the paper surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroacoustic transducer which is a flat speaker.

[0002]

2. Description of the Related Art FIG. 1 is a view for explaining an electro-acoustic transducer. FIG. 1A is a front view of the electro-acoustic transducer, and FIG. FIG. 2 is a view for explaining a diaphragm constituting a conventional electroacoustic transducer. FIG. 2A is a front view of the diaphragm, and FIG. FIG.

As shown in FIGS. 1 (A) and 1 (B), an overall-drive thin speaker unit A, which is an electroacoustic transducer, includes a frame 1, a rear plate 2, a magnet 3, a pole piece 4, a guide pin 5, a boiler. A coil 6, a diaphragm (diaphragm) 7, a damper 8, and an edge 9 are roughly constituted. The area of the diaphragm can be increased by increasing the number of combinations (segments) of the magnet 3, the boil coil 6, and the diaphragm (diaphragm) 7. The dimensions of the speaker unit A are, for example, a thickness of 25 mm,
The width is 115 mm, the height is 136 mm, the maximum amplitude is 10 mmp-p (at 600 gf), and the withstand power is 60 W.

The frame 1 is a frame formed of a heat-resistant resin such as a super heat-resistant ABS resin. The frame 1 is screwed and fixed to a speaker cabinet (not shown) via screw holes 1A to 1D provided at four corners thereof (the dimensions of the speaker cabinet are, for example, a thickness of 60 mm and a width of 1 mm).
20 mm, height 500 mm). A rear plate 2 is firmly screwed and fixed to the entire rear side of the frame 1, while four dampers 8 are adhesively fixed to four corners on the front side (diaphragm 7 side). The diaphragm 7 is formed by these four dampers 8.
The four corners are supported so as to freely vibrate.

The rear plate 2 is formed of a metal plate such as iron, and is a base plate for fixing the longitudinal magnets 3 having the longitudinal pole pieces 4 adhered to the upper surface thereof. A large number of air vent slits / holes are provided on the entire rear side of the rear plate 2 and a pair of speaker terminals connected to the start and end of the boil coil 6 are provided (neither is shown). On the other hand, both ends of the long pole piece 4 to which the long magnet 3 is adhered are screwed and fixed with the guide pins 5 on the front side (the diaphragm 7 side) of the rear plate 2 as described above. In the illustrated example, seven longitudinal magnets 3 are provided in parallel with each other.

The magnet 3 is a magnet obtained by sintering ferrite such as strontium ferrite. As described above, when this magnet 3 is fixed to the front side (diaphragm 7 side) of the rear plate 2, one surface of the magnet 3 in contact with the rear plate 2 becomes the N pole, while the magnet 3 in contact with the pole piece 4. The magnet 3 is magnetized so that the other surface (the diaphragm 7 side) of the magnet 3 becomes an S pole. The dimensions of the magnet 3 are, for example, 80 mm in length, 5 mm in width, and 8 mm in thickness.

The pole piece 4 is made of a metal plate such as iron, and has a pair of screw holes at both ends for fixing the magnet 3 to the rear plate 2. The boil coil 6 is provided with top portions 7a1 to 7a7 constituting the diaphragm 7.
Is a coated copper wire sequentially wound around each. As described above, the start and end (not shown) of the boil coil 6 are connected to a pair of speaker terminals provided on the rear plate 2 respectively.

The diaphragm (diaphragm) 7 is made of a polyimide (PI) film that withstands heat generated by the boiler coil 6 and has excellent mechanical properties as a diaphragm, and is integrally molded. Also, in order to reduce the weight of the diaphragm 7,
Although it is necessary to make the diaphragm itself as thin as possible, the thickness of the diaphragm 7 used here was 75 μm. As described above, the diaphragm 7 is mounted on the magnet 3 and the pole piece 4 fixed on the rear plate 2, and the periphery thereof is positioned and fixed to the frame 1 by an edge 9 made of urethane or the like. The specific configuration of the diaphragm 7 will be described later.

The damper 8 supports the vibration plate 7 so as to be able to vibrate freely, and is made of a thermoplastic resin such as polycarbonate, which is a material having high spring properties, impact resistance and heat resistance. In order to obtain a maximum amplitude of 10 mmpp in a limited space, a multi-stage leaf spring structure is used. Since the dampers 8 are fixed to the four corners of the frame 1, the displacement of each damper 8 is 150 gf and the displacement is 10 mm pp. This load is supported by a four-end support beam structure. Further, the structure is such that the tensile load in the plane direction of the diaphragm 7 is received by the connecting portion at the center of the damper 8. The beam structure is arranged in a fan shape to save space.

The above-mentioned diaphragm 7 is shown in FIG.
As shown in (B), the top part 7a1 is composed of a plurality of top parts 7a1 to 7a7, a plane part 7b, and an outer peripheral part 7c.
1 to 7a7, the flat portion 7b, and the outer peripheral portion 7c are integrally formed. In addition, the top portions 7a1 to 7a7 have a convex shape (raised) from the back side (the rear plate 2 side) of the vibrating plate 7 toward the front side.
The top portions 7a1 to 7a7 are integrally formed as a main vibrating portion 7A. Here, vibrating plate 7
Is the front side of the thin speaker unit A driven entirely. The tops 7a1 to 7a7 are in the longitudinal direction of the diaphragm 7 (FIG. 1).
2 (A) and 7 in the vertical direction in FIG. 2 (A), and the cross-sectional shape of each of the tops 7a1 to 7a7 is A- in FIG. It has a convex shape (semi-cylindrical shape, semi-cylindrical shape) cut along the line A '. An outer peripheral portion 7c is formed around the main vibrating portion 7A.

By supplying an audio signal (driving current) between the pair of speaker terminals of the thin speaker unit A having the above-described configuration, the tops 7a1 to 7a7 of the diaphragm 7 move relative to the paper surface. The whole surface vibrates uniformly before and after.

[0012]

As described above, the diaphragm (diaphragm) 7 is made as thin as possible to reduce the weight of the diaphragm itself and is integrally molded with a polyimide film. It is extremely difficult to keep the thickness of each part of the diaphragm 7 uniform. In particular, seven tops 7a
1 to 7a7, the direction perpendicular to the longitudinal direction (the horizontal direction in FIG. 1A and FIG. 2A) rather than the thickness in the longitudinal direction (the vertical direction in FIG. 1A and FIG. 2A). ) Has a drawback that the thickness becomes thin. For this reason, each top part 7a1-
The mechanical strength in the direction orthogonal to the longitudinal direction of 7a7 was poor. As a result, when an audio signal (drive current) of a relatively large level is supplied to drive the full-drive thin speaker unit A, the top portions 7a1 to 7a7 do not vibrate integrally as the main vibrating portion 7A. Each top 7
a1 to 7a7 did not vibrate uniformly, but vibrated separately, and the adjacent ridges collided with each other, and there was a risk of generating abnormal noise due to divided vibration (so-called “buzzy sound”).

As a result, in the above-described conventional full-drive thin speaker unit A, especially in the middle band (about 800 Hz to about 4 Hz).
(kHz), the sound pressure has a maximum dip of 40 dB, and the level fluctuation is much larger than other sound ranges. For this reason, a flat sound pressure frequency characteristic could not be obtained in the middle range.

According to the present invention, in order to solve the problem that a flat sound pressure cannot be obtained in all frequency bands, in particular, the rigidity of the outer peripheral portion 7c of the diaphragm 7 is reduced by adjusting the rigidity of each top portion 7c.
By making the stiffness higher than a1 to 7a7, even if the tops 7a1 to 7a7 are integrally vibrated as the main vibrating portion 7A, the occurrence of unnecessary resonance in the outer peripheral portion 7c is reduced and the acoustic distortion is suppressed. The purpose is to provide a vessel.

[0015]

To solve the above-mentioned problems, the present invention provides an electro-acoustic transducer having the following constitutions (1) and (2).

(1) As shown in FIG. 3, an electroacoustic transducer (an entire surface) for driving an entire planar vibration plate 70 in which a plurality of elongated protrusions (tops) 7a1 to 7a7 are formed in parallel. Driving thin speaker unit) AA, wherein the thickness of the outer peripheral portion 70c of the diaphragm 70 is greater than the thickness of the protrusions (top portions) 7a1 to 7a7, and the rigidity of the outer peripheral portion 70c is An electroacoustic transducer characterized in that the rigidity is higher than the tops) 7a1 to 7a7.

(2) A plurality of elongated protrusions (tops)
Planar diaphragm 7 in which 7a1 to 7a7 are formed in parallel
0 is an electroacoustic transducer (entirely driving thin loudspeaker unit) AA that drives the entire surface of the diaphragm 70.
An electroacoustic transducer provided with a member (iron or aluminum frame) different from the diaphragm 7 on 0c.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electroacoustic transducer according to the present invention will be described with reference to the drawings. FIG. 3 is a diagram for explaining a diaphragm constituting the electroacoustic transducer of the present invention.
The same components as those described above are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 3, the electro-acoustic transducer (full-surface driving thin speaker unit) AA of the present invention has a top 7
a1 to 7a7, the plane portion 7b, and the outer peripheral portion 7c are not all integrally formed of the same material and the same thickness of a homogeneous material, but the material or thickness of only the outer peripheral portion 70c is changed. Accordingly, the diaphragm 70 having the rigidity of the outer peripheral portion 70c further increased is used.

More specifically, the thin speaker unit AA, which is an electro-acoustic transducer of the present invention, is a fully driven thin speaker unit shown in FIG.
As shown in (B), the frame 1 includes a frame 1, a rear plate 2, a magnet 3, a pole piece 4, a guide pin 5, a boil coil 6, a diaphragm (diaphragm) 70, a damper 8, and an edge 9.

The diaphragm (diaphragm) 70 is made of a polyimide (PI) film that withstands heat generated by the boil coil 6 and has excellent mechanical properties as a diaphragm, and is integrally molded. As described above, the diaphragm 7 is mounted on the magnet 3 and the pole piece 4 fixed on the rear plate 2, and the periphery thereof is positioned and fixed to the frame 1 by an edge 9 made of urethane or the like.

As shown in FIG. 3, the diaphragm 70 includes a plurality of top portions 7a1 to 7a7, a flat portion 7b, and an outer peripheral portion 70c. The outer peripheral portion 70c is thicker than the top portions 7a1 to 7a7 and the flat portion 7b in order to increase the rigidity. For example, the plurality of top portions 7a1 to 7a7 and the flat portion 7b have a thickness of 75 μm, whereas the outer portion 70c has a thickness of 75 μm.
Has a thickness of about 2 mm.

As another method for increasing the rigidity of the outer peripheral portion 70c, a method of increasing the rigidity of the outer peripheral portion 70c by 400 μm to 50 μm
A metal frame with high rigidity such as iron or aluminum having a thickness of 0 μm is attached. For example, the rigidity (Young's modulus) of the outer peripheral portion 70c is 290 kg when the outer peripheral portion 70c is molded with a 75 μm thick polyimide (PI) film.
f / mm ² . On the other hand, when an aluminum frame is attached on the outer peripheral portion 70c, the outer peripheral portion 70c
The rigidity (Young's modulus) is 7000 kgf / mm ² , and approximately 24 times the rigidity can be obtained. In addition, the outer peripheral portion 70c
The rigidity (Young's modulus) of the outer peripheral portion 70c when an iron frame is stuck thereon is 21000 kgf / mm ² , and a rigidity of about 72 times can be obtained.

In this manner, the diaphragm 70 has an outer peripheral portion 70c.
Since the rigidity of the outer peripheral portion 70c is further increased by changing its material or thickness, an audio signal (drive current) is supplied between a pair of speaker terminals of the full-size drive thin speaker unit AA having the above-described configuration. By
Each of the top portions 7a1 to 7a7 of the diaphragm 7 can reduce the occurrence of unnecessary resonance (split vibration) in the outer peripheral portion 70c which occurs when the entire surface vibrates uniformly back and forth with respect to the paper surface, thereby suppressing acoustic distortion. it can.

[0025]

According to the electroacoustic transducer of the present invention having the above-described structure, the thickness of the outer peripheral portion of the diaphragm is increased or a member having high rigidity is provided thereon. By further increasing the rigidity, it is possible to provide an electroacoustic transducer that suppresses acoustic distortion by reducing the occurrence of unnecessary resonance (split vibration) in the outer peripheral portion even when the protrusions are vibrated integrally.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an electroacoustic transducer.

FIG. 2 is a diagram illustrating a diaphragm constituting a conventional electroacoustic transducer.

FIG. 3 is a diagram for explaining a diaphragm constituting the electro-acoustic transducer of the present invention.

[Explanation of symbols]

7, 70 diaphragm 7a1 to 7a7 top (projection) 7c, 70c outer periphery A, AA full-surface driven thin speaker unit (electroacoustic transducer)

Claims (3)

[Claims] 1. An electro-acoustic transducer for driving a whole of a planar diaphragm in which a plurality of elongated protrusions are formed in parallel, wherein the thickness of an outer peripheral portion of the diaphragm is determined by the thickness of the protrusion. An electroacoustic transducer, wherein the thickness is larger than the thickness, and the rigidity of the outer peripheral portion is larger than the rigidity of the protrusion. 2. An electro-acoustic transducer for driving a whole of a planar diaphragm in which a plurality of elongated protrusions are formed in parallel, wherein the diaphragm is provided on an outer peripheral portion of the diaphragm. An electroacoustic transducer comprising different members. 3. The electro-acoustic transducer according to claim 2, wherein the member provided on the outer peripheral portion of the diaphragm is an iron or aluminum frame.