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JPH066891

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DESCRIPTION JPH066891
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
full range speaker that enables high fidelity reproduction over a wide frequency band by using a
specific diaphragm.
[0002]
2. Description of the Related Art There are various types of speakers, but the most widely used at
present is a moving coil type dynamic speaker (hereinafter simply referred to as a speaker).
[0003]
In a high fidelity speaker aiming at high fidelity reproduction, it is required to exhibit flat
frequency characteristics with less distortion with respect to a human audible band ranging from
20 Hz to 20 KHz.
If you want to play with low distortion and high sound pressure in the low frequency range, a
diaphragm with a large aperture is required. However, diaphragms using materials such as pulp
that are commonly used in the past are not sufficiently high in bending rigidity, so when the
diameter is increased, divided vibrations in the high frequency range (portions moving in
opposite directions with nodes And the flatness of the frequency characteristic is lost. This is the
reason why a multi-way system is often used as a high fidelity speaker. Another reason is that
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there is no full-range speaker (speaker system using one speaker unit) having a sufficiently wide
reproduction frequency band, and conventionally, a full-range speaker is a poor grade speaker
with poor sound quality. It has been considered. However, full-range speakers have various
advantages that multi-way systems do not have, and their high-quality sound has been desired.
[0004]
In order to realize a full-range speaker with good sound quality, it is necessary to adopt a
diaphragm made of a material that does not easily cause divided vibrations, and at the same time
to increase the area of the diaphragm. In general, a diaphragm material having a high Young's
modulus is desirable because the frequency at which split vibration starts is high. On the other
hand, it is desirable for the diaphragm material to satisfy the second requirement that the
internal loss is large, but in general, the material having a higher Young's modulus tends to have
a smaller internal loss. For example, metal materials such as titanium, aluminum or beryllium
have a high Young's modulus but a small internal loss, while polymeric materials such as
polypropylene and pulp have a large internal loss but a low Young's modulus.
[0005]
Heretofore, no material has been known which simultaneously satisfies the above two
requirements and further has a good sound quality (eigensound) as a diaphragm.
[0006]
The inventors of the present invention have found that glass is suitable as a diaphragm material
having a high Young's modulus, a large internal loss and a good natural sound. 69930), the
shape of the glass plate and the method of attachment to the enclosure, etc., there is a problem
that the sound quality is greatly influenced, and it has not been easy to bring out the good
characteristics as a speaker.
[0007]
An object of the present invention is to obtain a full-range speaker having a wide reproduction
frequency band and good sound quality by improving the shape and mounting method of a glass
diaphragm.
[0008]
[Means for Solving the Problems] As a result of intensive studies to achieve the above object, the
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2
present inventor uses rectangular glass plates with a thickness of 0.2 mm or more and 20 mm or
less as diaphragms, and measures the length and width of the glass plates. It has been found that
the above object can be achieved when the length ratio of the length to the width 1 is 2 to 10
and the area is 400 cm 2 or more.
[0009]
The thickness of the glass diaphragm used in the present invention is 0.2 mm or more and 20
mm or less, but if it is less than 0.2 mm, it is likely to be broken, which is not preferable.
On the other hand, if it exceeds 20 mm, the energy required for driving becomes large and the
efficiency is significantly reduced, so the sound pressure can not be sufficiently increased at the
output of a normal amplifier, which is not preferable.
[0010]
In the present invention, a rectangular diaphragm is used as the glass diaphragm, but the ratio of
the length to width is preferably 2 to 10 with respect to width 1.
If the length is less than 2, the divided vibration can not be completely prevented and the sound
quality is degraded.
On the other hand, if the height exceeds 10, it may be difficult to install the speaker.
Further, the area of the glass diaphragm is preferably 400 cm 2 or more, but if it is less than 400
cm 2, sufficient sound pressure in the bass range can not be obtained.
[0011]
The material of the glass used in the present invention is not particularly limited. In the present
invention, glass is defined as an inorganic amorphous solid exhibiting a glass transition
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phenomenon. Specifically, for example, oxide glass such as borosilicate glass, soda lime glass,
potash glass, lead glass, quartz glass, special hard glass known by trade names such as Pyrex,
aluminosilicate glass, borate glass, phosphoric acid Salt glass, aluminate and titanate glass,
fluoride glass, chalcogen glass, metallic glass and the like. Furthermore, polycrystalline glass is
also included.
[0012]
The entire surface of the diaphragm or a part thereof is applied to the glass diaphragm used in
the present invention by applying various substances for various purposes, or adhering or
adhering a film-like or sheet-like substance. Can be coated. Furthermore, a multilayer glass plate
in which a film-like or sheet-like substance is inserted between two or more glass plates can be
used as a diaphragm. The purpose of such coating or insertion is, for example, to prevent
breakage of the glass or shattering when broken. Further, as another purpose, there are an
improvement in sound quality by increasing the internal loss, and an appearance improvement
by coloring.
[0013]
Since the glass diaphragm used in the present invention is high in strength, a damper used in a
normal cone type speaker is not necessary. In addition, even a diaphragm with a large area
exceeding 0.1 m2, sometimes reaching several m2, can stand independently without any
substantial deformation, so as a method of supporting the weight of the glass diaphragm, Not
only the method of hanging by an edge or the like, but also a method of mounting directly on the
lower support of the enclosure may be adopted.
[0014]
In the present invention, the number of driving voice coils may be one or more. Alternatively, the
magnetic circuit may be attached to the enclosure via a frame like a normal cone speaker, but the
direct attachment to the enclosure is preferable. In the case of direct attachment, an inorganic
material having a high elastic modulus and a high density inside the back plate, such as concrete,
brick, ceramic, glass, in order to suppress unwanted radiation noise from the enclosure caused by
the reaction received by the magnetic circuit. It is desirable to attach a plate or block made of a
kind of material selected from the group consisting of stone and the like, and to bond the
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magnetic circuit on it. The above method is different from the known method of attaching a brick
or iron block to a magnetic circuit on a frame, which is known in a cone speaker, not only in the
attaching method but also in the action mechanism.
[0015]
The glass diaphragm is attached to the frame or enclosure, but the junction between the two, i.e.
the edge, is the part that greatly affects the sound quality. In general, the edge material is
inserted between the periphery of the glass diaphragm and the frame or enclosure, etc., and is
joined with both by an adhesive or the like, and works to keep its position accurately while
flexibly following the movement of the diaphragm. However, the edge material also prevents
mutual interference of the air before and after the diaphragm. The material of the edge is
desirably soft and highly elastic. For example, polyurethane, coated cloth, rubber other than
polyurethane, thermoplastic elastomer, etc. are suitable, and foams of the above-mentioned
various materials can also be used. Furthermore, the shape is also important, and not only roll
edges often used in cone speakers but also edge materials having a cross-sectional shape such as
U, P, L or O can be used. In particular, in order to ensure mechanical linearity of vibration with
respect to the input signal, it is desirable to attach the edge material of the U-shaped cross
section so that the side of U is parallel to the diaphragm.
[0016]
In order to bow the glass diaphragm, for example, there is a method in which both end portions
in the longitudinal direction are pressed inward by a fixing bar or the like, a method using a glass
plate formed in a warped state, or the like. When the fixing bar is used, the glass diaphragm
receives an outward force by the edge material at the central portion in the longitudinal
direction, and is warped outward. It is desirable that the height difference between the central
portion of the arch and both ends be 1/2000 or more and 1/10 or less of the longitudinal length.
If it is less than 1/2000, the effect is small, and if it exceeds 1/10, the mechanical linearity of the
vibration with respect to the input signal is lost. The direction of the warp may be convex
outward or may be convex inwardly.
[0017]
The enclosure used in the present invention may be about the same as that used in a
conventional cone speaker, but due to the large diaphragm area, there may be a design where
substantially no front baffle is present.
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[0018]
[Operation] The frequency at which the divided vibration starts is influenced not only by the
physical properties of the diaphragm but also by the shape thereof.
Even if it is a glass diaphragm, if it is a square, that is, if the ratio of length to width is a plane of
length 1 to width 1, it is affected by the thickness and area, although it can not be said
indiscriminately, the division vibration is It may start from 100 Hz.
[0019]
The glass diaphragm used in the present invention emits a sound wave mainly by forced elastic
vibration of the plate, instead of producing sound by piston movement like a diaphragm used in a
normal cone speaker. In the case of the glass diaphragm of the above-mentioned shape according
to the present invention, that is, in the case of a strip having a length ratio of 2 to 10 with respect
to the width to width 1, the bending movement mainly occurs in the longitudinal direction. It is
possible to prevent the occurrence of divided vibration inside, in other words, nodes.
[0020]
The effect of the divisional vibration suppression can be further enhanced by bending the stripshaped plate in the longitudinal direction in advance. Although the glass diaphragm performs a
bending motion, the required curvature is small because the curvature in the vertical direction is
large and the area is large, and when focusing on a specific minute surface on the diaphragm, air
is required. The relative relationship with can be regarded as substantially the same as in the
case of piston movement. However, the amplitude of the glass diaphragm is large at the central
portion in the vertical direction and is small at both ends. In this respect piston movement is
essentially different.
[0021]
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1 and 2 show an embodiment of a full range speaker using a glass diaphragm according to the
present invention, but schematically showing the positional relationship between the respective
parts, in which actual dimensions are proportional to each other. Is not illustrated. Describing
with reference to the drawings, in FIG. 1, a rectangular glass plate with a thickness of 3.0 mm, a
length of 100 cm, and a width of 20 cm was used as the diaphragm 1. A PET film is attached to
the glass plate for the purpose of preventing damage and increasing internal loss. The diaphragm
1 is mounted on the lower rubber plate of the enclosure, and is fixed to the wooden enclosure 10
at two places in the upper and lower portions by the fixing bars 11, and the diaphragm is bowed
outwardly convex in the longitudinal direction. The height difference between the central part
and both ends is 3 mm.
[0022]
A cylindrical strong plastic bobbin 3 is fixed to the center of the diaphragm by an epoxy
adhesive. The bobbin 3 is wound with a voice coil 2 having a nominal impedance of 8 Ω.
[0023]
The magnetic circuit is of the external magnet type, and comprises a ferrite-based cylindrical
permanent magnet 5, an iron plate 4 and a pole piece 7. The magnetic circuit is adhesively
bonded onto a concrete plate 12 mounted inside the back plate of the enclosure.
[0024]
Between the diaphragm 1 and the enclosure 10, there is a space surrounded by a 15 mm-thick
foamed polyurethane sound absorbing material 9. The end of the sound absorbing material 9
stretched on the side plate and the upper plate is bonded to the diaphragm via the edge member
6 having a U-shaped cross section made of rubber. The detail of the edge material in a side plate
part is shown in FIG.
[0025]
The acoustic signal supplied from the amplifier is transmitted from the terminal 8 to the voice
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coil 2 through the lead wire. The speaker produced in this way can cover almost the entire
audible range, the sound pressure level in the high range is also high, the directivity is good, and
natural and stretchy sound that seems like a full range speaker put out.
[0026]
Since the present invention is configured as described above, the following effects can be
obtained.
[0027]
By making the shape of the glass diaphragm rectangular and having a length of 2 to 10 and a
area of 400 cm 2 or more with respect to width 1, division vibration can be prevented, a wide
reproduction frequency band and sufficient sound pressure can be secured, and high sound
quality The full range of speakers became possible.
As a result, various problems often found in multi-way systems, such as distortion caused by
dividing network circuits, discomfort due to differences in material of diaphragm between woofer
and squaker or tweeter, localization of sound image Badness etc. can be avoided, and a
reproduced sound with high purity and natural nature can be obtained.
[0028]
And, by bending the glass diaphragm in the longitudinal direction in the longitudinal direction, it
is possible to make the prevention of the divided vibration more reliable.
[0029]
Furthermore, by making the cross-section of the edge material U-shaped, mechanical linearity of
vibration with respect to the input signal can be secured, and distortion at high volume can be
prevented.
[0030]
Moreover, unnecessary radiation noise is suppressed and the sound quality is improved by
joining the magnetic circuit on a plate or block made of an inorganic material with high elasticity
and high density such as concrete attached to the inside of the back plate of the enclosure. .
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[0031]
In addition, since it is easy to increase the area of the diaphragm, freedom in designing sound
quality and appearance is increased, and it is possible to meet a wide range of needs.
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