Speaker device

Details Speaker device Speaker device

2000-01-24

2002-04-16

Chin, Peter (Department: 1731)

Acoustics

Diaphragm

Mounting or suspension means

C162S221000, C162S222000, C162S224000, C162S231000

Reexamination Certificate

active

06371241

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a speaker which converts an electrical voice signal to a sound wave. In particular, the present invention relates to a frame for a speaker.
DESCRIPTION OF THE PRIOR ART
Up to the present time, the material used in the frames of speakers has been metal plate of which thin steel plate, press molded aluminum plate, cast products made from metallic alloys such as zinc or aluminum alloys or products made from injection molding of thermoplastic resins are examples.
For example,
FIG. 11
is a cross sectional schematic view of the layout of a speaker unit using metallic plate.
FIG. 12
is a front view of an example of a frame used in the speaker in FIG.
11
.
In the figures, after a caulking joggle
2
a
of an upper plate
2
is inserted into a slit
1
b
formed in the lower end of the frame
1
, both components are fixed by a caulking deformation process applied to the top section.
A magnet
4
is sandwiched and fixed between the upper plate
2
and the pole piece
3
by adhesive. It is noted that the magnetic circuit of the speaker is formed by the upper plate
2
, the pole piece
3
and the magnet
4
.
A gap termed an “air gap”
14
is formed between the upper plate
2
and the pole piece
3
. A voice coil
5
a
is disposed in the gap and is wound onto a bobbin
5
. The coil
5
a
generates a sound wave by creating a mechanical displacement due to an input signal and transmits the displacement to a diaphragm
8
.
The voice coil
5
a
wound on the bobbin
5
is supported by a damper
10
, an outer section of which is fixed to the frame
1
and by an edge
9
, an outer section of which is fixed to the frame
1
in the same way. The center of the coil is arranged so that it moves in the air gap
14
without deviation. The edge
9
is fixed to and integrated with diaphragm
8
. A center cap
8
a
is mounted on the diaphragm
8
.
A terminal board
11
mounting terminals
12
is fixed by an eyelet or the like to the other frame
1
. Reference numeral
6
denotes a gasket with the functions reinforcing the frame
1
and acting as an interface with the other mounted components.
An input signal from a terminal
12
is supplied to the voice coil
5
a
through the tinsel cord
13
.
1
a
is a window,
1
d
in
FIG. 12
is a strain absorption hole,
1
e
is a strain absorption notch.
Generally, metallic plate is widely used in the frames of speakers incorporated in vehicle-mounted music devices or household audio-visual devices due to their excellent qualities and low price. The disadvantage of metallic plate resides in the deterioration of sound quality in the speaker.
The reason for such a deterioration is that self-resonance in the frame is easily induced when the diaphragm of the speaker is oscillated by a sound signal. Furthermore the frequency of such self-resonance is realized in an audible frequency band. Self-resonance is caused by vibration transmitted from the outside to the speaker.
For example, the self-resonance frequency of a speaker with a 13 cm aperture using a 0.7 mm. thickness aluminum frame displays a distribution about 1.5 KHz. Frequencies in the vicinity of 1.5 KHz are faintly audible. That is to say, fidelity is reduced since vibrations of the diaphragm due to the sound signal and the vibration of the frame due to self-resonance become mixed in and are audible.
The problem of self-resonance does not particularly arise in the context of zinc cast products. However casting as a method of fabrication results in cost increases associated with the considerable secondary processing required to achieve a desired shape.
Although resin molded products display superior productivity, generally they have a low mass and share the disadvantage of metallic plate in that self-resonance results from externally applied vibrations.
The simplest method of increasing mass is to increase the thickness of the member. However when this method is applied to the frames of speakers, the outer shape increases together with increases in thickness and thus reduces freedom of disposition of the speaker and poses problems for use m cramped environments such as vehicle compartments.
The relationship of the above materials to environmental protection will be discussed below. When the product life of industrial components expires, it is needless to say that recycling of component materials or disposal with little effect on the environment is desirable. Speakers are no exception to this rule.
Up until the present time, the dismantling and reuse of metallic plate of used speakers has almost never been put into practice. For example, metallic members such as upper plates
2
are fixed strongly by a method such as caulking, adhesion or welding to the frame
1
and thus the subsequent dismantling of these components is physically difficult.
Overall processing costs are created by the processing costs, wage costs and time costs of dismantling the device. Thus even if instituted, such processes showed few economic benefits. Thus used speakers are in actuality usually disposed of in land fills and this as a result represents a waste of resources.
Disposal in land fills is not always an effective method in view of used materials. For example, resin products display extremely low decomposition over time in comparison with metal even when buried in earth or water. Needless to say, this is undesirable from the point of view of environmental protection.
In summary therefore, when molded resin or pressed metal products are used in the frame of speakers, problems with respect to acoustics result even though productivity is excellent. Cast zinc products entail problems with respect to both costs and productivity. Both such products require long periods of time to be decomposed by micro-organisms in the natural world and do not display characteristics oriented to a process of effective recycling or a method of disposal with little effect on the environment.
A known method of manufacturing paper products called fine pulp molding is used in packing containers or packing (i.e. buffer) material as a means of solving the above mentioned problems. Fine pulp molding combines molding and paper manufacturing in a type of manufacturing paper products and is a processing method which creates a three dimensional shape with high levels of accuracy with a pulp material. This method of manufacturing paper products will simply be termed fine pulp molding hereafter.
A characteristic of fine pulp molding is that it is an integrated method of paper manufacturing three dimensional shapes using a combined male-female paper making mold. Another characteristic of the molding is the external beauty of product and it is known for superior characteristics with respect to dimensional accuracy and productivity for paper products having a three dimensional shape.
In addition, the method has the advantage that apart from virgin pulp old paper, disposed paper material such as old paper may be used as material. Thus it is possible to increase the use of old paper which is perceived to create problems of oversupply in the market place and to promote recycling. On the other hand, it is possible to greatly reduce material costs and to reduce manufacturing costs.
An outline of the process of fine pulp molding will be described below. A model of the process is shown in FIG.
13
.
Fine pulp molding entails three main sequential steps.
(a) Adhesion step: a male paper manufacturing mold
20
is immersed in a pulp dissolving fluid
23
and pulp is adhered to the male paper manufacturing mold
20
by vacuum suction.
(b) Dehydration/Molding step: a female paper manufacturing mold
21
is pressed onto the pulp which has adhered to the male paper manufacturing mold
20
and dehydration and molding are performed.
(c) Drying step: after pressing and drying with a heated mold onto the pulp which has been shaped by the previous step, the product (pulp mold product
25
) is extracted.
Detailed description is outlined below. In
FIG. 13
, a male paper manufacturing mold
20
is immersed in pulp dissolving fluid
2

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