JP2000032588A - Electroacoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent, as much as possible, a damper with a circular arc plate spring from being destroyed, due to a stress such as torsion. SOLUTION: This electroacoustic transducer is constituted with a frame mount 2 where a damper 1 placed to an upper side or a lower side and its both ends of a frame and that is fixed to the frame, a diaphragm support 3 that is placed in the inside of the frame mount 2 and over the upper side or the lower side of a diaphragm and its both ends to support the diaphragm, and a couple of plate sprints 4 that are connected at both ends of the diaphragm support and the frame mount 2 respectively. Each plate spring 4 consists of a 1st plate spring 5 of a circular arc shape whose both ends are supported by the frame mount 2, a 2nd plate spring 6 of circular arc whose both ends are supported by the diaphragm support 3, and a connection section 7 that connects nearly middle parts of the 2nd plate spring 6 and the 1st plate spring 5. In this case, the thickness at the inner circumferential side near the support 5a with the connection part 7 in each 1st plate spring 5 is set larger than that of the outer circumferential side and the width of the support 5a, with the connection part 7 being selected wider than the width of the support 5b with the frame mount 2.

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 driven entirely.

[0002]

2. Description of the Related Art FIG. 7A is a front view of a conventional electroacoustic transducer of this type, and FIG. 7B is a sectional view thereof. FIG.
1A and 1B, a frame 30 is a rectangular frame, and a substantially flat diaphragm 31 is provided in the frame 30.
Is arranged. A rectangular frame-shaped edge 32 is adhered to the entire outer peripheral edge of the diaphragm 31, and the entire outer peripheral edge of the edge 32 is fixed to the frame 30. Diaphragm 3
1 is supported in the frame 30 via the edge part 32 so as to be freely vibrated.

A main vibrating portion 31a protruding toward the front side of the vibrating plate 31 and extending in a certain direction (vertical direction in the figure).
Are provided at regular intervals. Each main vibrating part 31
A coil coil 33 (shown in FIG. 7 (b)), which is a covered conductor, is wound around a, so that a drive current can be supplied to the coil coil 33. The diaphragm 31 is made of a polyimide (PI) film that withstands heat generated by the boil coil 33 and has excellent mechanical properties as the diaphragm 31.

[0004] A rear plate 34 is fixed to the rear surface side of the frame 30, and the rear plate 34 is made of a metal plate such as iron. Magnets 35 are fixed to the vibration plate side of the rear plate 34 and at positions corresponding to the respective main vibrating portions 31a, and pole pieces 36 are fixed to the upper surfaces of the respective magnets 35. The pole piece 36 is made of iron or the like, and the magnet 35
For concentrating the magnetic flux. That is, a magnetic circuit is constituted by the rear plate 34, the magnet 35, the boil coil 33, and the like.

On the upper surface of each main vibrating portion 31a of the diaphragm 31, a substantially semi-cylindrical surface 39a protruding outward and a substantially semi-cylindrical surface 39b depressed inward are alternately arranged in the longitudinal direction. Shape. With such a shape, mechanical strength (rigidity) against force in the direction perpendicular to the longitudinal direction
Are strengthened, and when one starts to vibrate larger or smaller than the other without the boundary portions being aligned and vibrating, the generation of the vibration component is prevented beforehand.

At the four corners on the inner periphery of the frame 30 and on the surface side of the edge portion 32, dampers 37 are disposed, and each of the dampers 37 comprises a frame attachment portion 37a and a diaphragm support portion 37b on the inner periphery. And a leaf spring portion 37c connecting these. Frame mounting part 37a
Is fixed to the frame 30, and the diaphragm support portion 37b
Are in contact with the upper and lower ends of the main vibrating portion 31a located at the left and right ends of the diaphragm 31.

That is, the damper 37 is provided with the diaphragm supporting portion 37.
Although the diaphragm 31 is supported by b, the vibration itself of the diaphragm 31 is allowed by the spring force of the leaf spring portion 37c. Damper 37
Is made of a thermoplastic resin such as polycarbonate, which is a substance having high spring resistance, high impact resistance and high heat resistance.

In the above configuration, when a magnetic field is generated around the boil coil 33 by the magnet 35 and a drive current flows through the boil coil 33, an electromagnetic force corresponding to the drive current acts on the boil coil 33, and this electromagnetic force causes main vibration. Part 31a
The diaphragm 31 mainly vibrates.

The damper 37 is provided on the diaphragm 31.
Since the four corners are supported, there is a problem that the upper and lower sides of the diaphragm 31 cannot be reliably supported, and the present applicant has previously proposed the damper 1 shown in FIG.
-284528 application). In FIG. 8, the damper 1 is a pair of upper and lower members for supporting the diaphragm 31 so as to be able to vibrate freely, and has the following configuration. The damper 1 is arranged over the upper side or the lower side of the frame 30 and both ends thereof, and a frame mounting portion 2 fixed to the frame 30, and the upper side or the lower side of the diaphragm 31 inside the frame mounting portion 2. And a pair of leaf springs 4 disposed at both ends thereof for supporting the diaphragm 31 and connected at both ends of the diaphragm support 3 and the frame mounting part 2. , 4 and are made of resin.

Both ends of the frame mounting portion 2 and the diaphragm supporting portion 3 are formed in an arc shape following the shape of both ends of the frame 30, and the inner peripheral side of the diaphragm supporting portion 3 has five main portions. 5 so as to hold the upper end face or the lower end face of the vibrating section 31a.
It is configured as one circular surface 3a.

Each leaf spring portion 4 has an arc-shaped first leaf spring portion 5 having both ends supported by the frame mounting portion 2 and an arc-shaped second leaf spring having both ends supported by the diaphragm supporting portion 3. Part 6
And a connecting portion 7 for connecting between the second leaf spring portion 6 and a substantially central portion of the first leaf spring portion 5.

According to the damper 1, both the upper side and both ends of the diaphragm 31 and the lower side and both ends thereof can be reliably supported. Further, the tensile load in the vertical direction of the diaphragm 31 is reliably held.

By using the arc-shaped leaf spring portions 5 and 6 like the damper 1, the damper 1 can be efficiently disposed in a narrow space even if the leaf spring has a long "low spring constant". In addition, there is an advantage that the use of resin increases the degree of freedom of the shape and enables mass production at low cost.

[0014]

However, when the damper 1 is made of resin, it is necessary to prevent stress concentration in particular because the breaking strength is lower than that of metal. No action was taken.
More specifically, the vibration plate 31 vibrates together with the vibration of the vibration plate 31. At this time, the arc-shaped first leaf spring portion 5 undergoes displacement such as torsion, and the stress due to the torsion displacement or the like is a problem. Becomes

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and provides an electroacoustic transducer having a damper in which an arc-shaped leaf spring portion is not likely to be broken by stress due to torsion or the like. With the goal.

[0016]

According to a first aspect of the present invention, a substantially flat diaphragm is supported in a frame so as to vibrate freely, and a pair of upper and lower resin dampers are arranged at the upper and lower portions of the frame. And each of the dampers is disposed over the upper side or the lower side of the frame and both ends thereof, and a frame mounting portion fixed to the frame, and the upper side or the lower side of the diaphragm and the upper side or the lower side thereof inside the frame mounting portion. A diaphragm supporting portion that is disposed over both ends and supports the diaphragm, and a pair of leaf spring portions that are connected at both ends of the diaphragm supporting portion and the frame mounting portion, respectively. The leaf spring portion has a first arc-shaped leaf spring portion having both ends supported by the frame mounting portion, an arc-shaped second leaf spring portion having both ends supported by the diaphragm supporting portion, and the second leaf spring. And the middle of the first leaf spring part An electroacoustic transducer comprising a connecting portion connecting between the portions, wherein each of the first leaf spring portions has a width and / or a thickness set so as to reduce a maximum stress due to a displacement accompanying vibration of the diaphragm. It is characterized by having done.

According to a second aspect of the present invention, there is provided the electroacoustic transducer according to the first aspect, wherein each of the first leaf spring portions has a thickness on an inner peripheral side near a supporting portion with the connecting portion from an outer peripheral side. It is characterized by being set thick.

According to a third aspect of the present invention, there is provided the electroacoustic transducer according to the first aspect, wherein each of the first leaf spring portions has a support portion with the frame attachment portion based on a width of the support portion with the connection portion. Is set wide.

According to a fourth aspect of the present invention, there is provided the electroacoustic transducer according to the first aspect, wherein each of the first leaf spring portions has a support portion with the frame mounting portion based on a width of the support portion with the connection portion. And the thickness of the inner peripheral side near the support portion with the connecting portion is set to be thicker than the outer peripheral side.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a damper of an electroacoustic transducer according to an embodiment of the present invention, FIG. 2 is a plan view of a main part of the damper, FIG. 3 is a sectional view taken along line AA of FIG. Is B in FIG.
FIG.

1 to 4, the electroacoustic transducer of this embodiment has the same configuration as that of the above-described conventional example except for the configuration of a damper 1. FIG. The configuration of the damper 1 is also substantially the same as that of the conventional example shown in FIG. 8, and therefore, the same components are denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

That is, in this embodiment, the width and / or thickness of each first leaf spring portion 5 is set so that the maximum stress due to the displacement caused by the vibration of the diaphragm 31 is reduced. Specifically, each of the first leaf spring portions 5 includes a support portion 5 a with the connecting portion 7.
The thickness t1 on the inner peripheral side in the vicinity is set to be thicker than the thickness t2 on the outer peripheral side (t1> t2). In each of the first leaf spring portions 5, the width d2 of the support portion 5b with the frame mounting portion 2 is wider than the width d1 of the support portion 5a with the connection portion 7 (d1
<D2) It is set.

In the above configuration, when a magnetic field is generated around the boil coil 33 by the magnet 35 and a drive current flows through the boil coil 33, an electromagnetic force corresponding to the drive current acts on the boil coil 33, and the main vibration is generated by the electromagnetic force. Part 31a
The diaphragm 31 mainly vibrates. Each vibration plate supporting portion 3 of the pair of upper and lower dampers 1 accompanying the vibration of the vibration plate 31
Are displaced (perpendicularly to the plane of FIG. 1 and FIG. 2) against the spring force of the first and second leaf spring portions 5 and 6.

Here, the first leaf spring portion 5 has the largest torsion angle in the vicinity of the supporting portion 5a with the connecting portion 7, and the maximum stress is different between the inside and the outside. The thickness t1 on the inner peripheral side in the vicinity of the supporting portion 5a is set to be thicker than the thickness t2 on the outer peripheral side (t1> t2), so that the maximum stress value is suppressed to a low value and the maximum stress value is not exceeded, and fracture is prevented. Does not occur.

In the first leaf spring portion 5, the width d2 of the support portion 5b with the frame mounting portion 2 is set to be wider (d1 <d2) than the width d1 of the support portion 5a with the connection portion 7. Since the torsion angle of the first leaf spring portion 5 is kept small, the maximum stress value is kept low, so that the maximum stress value is not exceeded and no breakage occurs.

In the above embodiment, both the width and the thickness of the first leaf spring portion 5 are controlled, but only one of them may be controlled. That is, each first leaf spring portion 5 may simply set the thickness t1 on the inner peripheral side near the support portion 5a with the connecting portion 7 to be larger than the thickness t2 on the outer peripheral side (t1> t2). In this case, when the equivalent stress of von Mises on the line L connecting point a to point b in FIG. 5 was numerically analyzed, the stress characteristic indicated by the solid line in FIG. 6 was obtained. The maximum stress value is suppressed lower than the stress characteristic of the conventional example shown by the broken line in FIG. 6, and the position of the maximum stress also changes.

Each of the first leaf spring portions 5 is connected to the connecting portion 7.
The width d2 of the support portion 5b with the frame mounting portion 2 may be set to be wider (d1 <d2) than the width d1 of the support portion 5a. However, it is preferable to control both the width and the thickness of the first leaf spring portion 5 as in the above-described embodiment, since the maximum stress can be further reduced.

[0029]

As described above, according to the first aspect of the present invention, a substantially flat diaphragm is supported in a frame so as to be able to vibrate freely, and a pair of upper and lower resin members are provided on the upper and lower portions of the frame. Are disposed over the upper side or lower side of the frame and both ends thereof, and a frame mounting portion fixed to the frame, and an upper side of the diaphragm inside the frame mounting portion are provided. Or a diaphragm supporting portion which is disposed over the lower side and both ends thereof and supports the diaphragm, and a pair of leaf spring portions which are connected at both ends of the diaphragm supporting portion and the frame mounting portion, respectively. Each of the leaf spring portions has an arc-shaped first leaf spring portion having both ends supported by the frame mounting portion, an arc-shaped second leaf spring portion having both ends supported by the diaphragm supporting portion, and Second
An electro-acoustic transducer including a leaf spring portion and a connecting portion that connects between a substantially central portion of the first leaf spring portion, wherein each of the first leaf spring portions has a maximum due to displacement caused by vibration of the diaphragm. Since the width and / or thickness is set so as to reduce the stress, the stress of the first leaf spring portion can be within the allowable stress value, and destruction due to the first leaf spring portion exceeding the allowable stress value is prevented as much as possible. it can.

According to the second aspect of the present invention, since the thickness of the inner peripheral side in the vicinity of the support portion with the connecting portion is set to be thicker than that of the outer peripheral side, the maximum stress value of each first leaf spring portion can be suppressed low. In addition, destruction due to exceeding the allowable stress value can be prevented as much as possible.

According to a third aspect of the present invention, since the width of the support portion with the frame mounting portion is set to be wider than the width of the support portion with the connecting portion, the maximum stress value is suppressed. Therefore, destruction due to exceeding the allowable stress value can be prevented as much as possible.

According to a fourth aspect of the present invention, in each of the first leaf spring portions, the width of the support portion with the frame mounting portion is wider than the width of the support portion with the connection portion, and the width of the support portion with the connection portion is increased. Since the thickness on the inner peripheral side in the vicinity is set to be larger than that on the outer peripheral side, the maximum stress value is suppressed to be low, and breakage due to exceeding the allowable stress value can be prevented as much as possible.

[Brief description of the drawings]

FIG. 1 is a plan view of a damper of an electroacoustic transducer according to an embodiment of the present invention.

FIG. 2 is a plan view of a main part of a damper of the electroacoustic transducer according to the embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a view taken in the direction of arrows BB in FIG. 2;

FIG. 5 is a plan view of a principal part for stress analysis of a damper of the electroacoustic transducer according to one embodiment of the present invention.

FIG. 6 is a stress characteristic diagram showing the results of numerical analysis of the equivalent stress of von Mises in the case of the present embodiment and the case of the conventional example.

FIG. 7A is a plan view of a conventional electroacoustic transducer,
(B) is a sectional view of the electroacoustic transducer.

FIG. 8 is a plan view of another conventional damper.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Damper 2 Frame attachment part 3 Diaphragm support part 4, 4 A pair of leaf spring parts 5 First leaf spring part 5a, 5b Support part 6 Second leaf spring part 7 Connecting part 30 Frame 31 Vibration plate

Claims (4)

[Claims] A substantially flat vibration plate is supported in a frame so as to vibrate freely, and a pair of upper and lower resin dampers are disposed at an upper portion and a lower portion of the frame, respectively. Or a frame mounting portion fixed to the frame and disposed over the lower side and both ends thereof, and the diaphragm disposed over the upper side or lower side of the diaphragm and both ends thereof inside the frame mounting portion And a pair of leaf spring portions connected at both ends of the diaphragm support portion and the frame mounting portion. Each leaf spring portion has both ends on the frame mounting portion. An arc-shaped first leaf spring portion supported, an arc-shaped second leaf spring portion having both ends supported by the diaphragm supporting portion,
An electro-acoustic transducer including a second plate spring portion and a connecting portion that connects between substantially a central portion of the first plate spring portion, wherein each of the first plate spring portions is associated with vibration of the diaphragm. An electroacoustic transducer characterized in that the width and / or the thickness are set so that the maximum stress due to displacement is reduced. 2. The electroacoustic transducer according to claim 1, wherein each of the first leaf spring portions has a thickness on an inner peripheral side near a support portion with the connecting portion set to be thicker than an outer peripheral side. Characteristic electro-acoustic transducer. 3. The electroacoustic transducer according to claim 1, wherein each of the first leaf spring portions has a width of a support portion with the frame mounting portion wider than a width of a support portion with the connection portion. An electro-acoustic transducer, characterized in that: 4. The electroacoustic transducer according to claim 1, wherein each of the first leaf spring portions has a width of a support portion with the frame attachment portion larger than a width of a support portion with the connection portion, as well as,
An electroacoustic transducer characterized in that the thickness on the inner peripheral side near the support portion with the connecting portion is set to be thicker than the outer peripheral side.