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JPH0440198

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DESCRIPTION JPH0440198
[0001]
Industrial Field of Application This invention relates to the improvement of acoustic lenses used
for speakers in acoustic devices. [Prior Art] Conventionally, as this type of acoustic lens, one
shown in FIG. 1 is known, and in the figure, (1) is an acoustic lens. Next, the operation will be
described. That is, when an input signal is applied to the driver unit attached to the open end of
the acoustic lens, a driving force is generated in the voice coil located in the magnetic field, the
driving force is transmitted to the vibration system, and the vibration system is vibrated. Sound is
emitted from the diaphragm by vibration. The sound emitted from the diaphragm is transmitted
through the acoustic lens (1), controlled by the acoustic lens (1), and emitted as sound from the
surface. Usually, as a material of the acoustic lens (1), a metal such as aluminum having a
relatively high rigidity and a small internal loss, or a plastic which is easy to form but is low in
rigidity and easy to emit an inherent sound is used. In addition, the wooden one has a large
internal loss and relatively high rigidity, but the weight and thickness are also large, it tends to be
large, and the workability is poor. As described above, the sound directly emitted from the
diaphragm is controlled by the acoustic lens (1) to become the intended sound emission.
Therefore, in designing, in consideration of mechanical strength, in order to suppress an
unnecessary width pair due to the vibration of the acoustic lens (1) itself, it is necessary to devise
a material having a large internal loss or the like. By the way, since it is considered ideal that only
the diaphragm does not vibrate at the time of sound radiation, the acoustic lens (1) mounted on
the driver needs to use a material having high rigidity and large internal loss. [Problems to be
Solved by the Invention] In the conventional example in which the fixing method is strengthened
in order to suppress radiation due to unnecessary vibration of the acoustic lens (1), and in the
conventional example in which the thickness is increased, the increase in weight is possible
Leading to deterioration of workability. Further, in the conventional example in which a material
having a large internal loss is attached as described above, the invention of the present invention
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has problems such as deterioration of workability, and instability of quality due to variations in
effects due to changes in thickness and shape. The present invention has been made to solve the
conventional problems, and has an object to obtain an acoustic lens which has no deterioration in
sound quality, has the same workability as the conventional one, and can obtain inexpensive and
faithful reproduced sound. [Means for Solving the Problems] The acoustic lens for a speaker
according to the present invention is an anti-vibration aluminum alloy or damping ability of an
Al-5i system in which the damping ability (Q- 'X 10-3) is set to 8 to 1 o It is comprised with the
material which consists of the anti-vibration aluminum alloy of the AI-Ni system which QX10-: l
was set to 8-9.
[The acoustic lens according to the present invention uses the above-mentioned specific Al-5Lbased or Al-Ni-based anti-vibration aluminum alloy as its constituent material, thereby increasing
internal loss while maintaining the rigidity of the acoustic lens itself. The radiation due to the
unnecessary vibration is suppressed. An embodiment of the present invention will be described
below. That is, in FIG. 1, (1) is an acoustic lens using the aluminum alloy of the Al-5i system or AlNi system according to the present invention. Next, examples of alloys used for the acoustic lens
of the present invention will be shown. Example 15i-10%, Fe-0,05%, Zr-0,05%, MM * -0,1%, Na0,002%, A1-remaining Example 2Si-10%, Fe-0, 05%, Zr-0, 05%, MM * -0, 1%, 5n-0, 08%, A1remaining. Example 3 Ni-6%, Fe-0,05%, Zr-0,05%, MM * -0,1%, Al-remaining. Example 4 Ni-6%,
Fe-0,05%, Zr-0,05%, MM * -0,1%, 5n-0,08%, Al-remaining. MM *: metal (composition: La 35%, Ce
43%, Na 15%, Pr 4%, 5I 111%, others 2%) Examples 1 and 2 show Al-3i, and Examples 3 and 4
show AI Ni. Generally, as a mechanism causing internal friction (damping) in an aluminum alloy,
second phase particles, viscous flow at matrix boundaries, grain boundaries and grain
boundaries, and micro defects in crystals such as dislocations, voids and stacking faults
Absorption of vibrational energy by Damping ability Q- 'indicates a scale for converting
externally applied vibrational energy into thermal energy, and 2πE (E: vibrational energy of the
vibration system at the beginning of one cycle of vibration) (ΔE: one of the vibration) Energy to
be converted to thermal energy during cycling) In the Al-Si i-based vibration-damping aluminum
alloy of the present invention, when Si is added to A and l, Si particles are precipitated in the
matrix Al and Form crystals. The interface of the 81 particles, which is the second phase, absorbs
the vibration to improve the damping capacity Q-1. On the other hand, Fe, Zr, V, Ti and rare earth
elements have the function of refining the crystal to increase grain boundaries, and Na and Sr
have the function of refining Si particles. Further, when Sn is contained as in the second
embodiment, the precipitates are finely precipitated in the grain boundaries, the viscosity of the
grain boundaries is increased, and the damping ability is improved. By the way, the weight
percentage of the above-mentioned Al-5i-based vibration-proof aluminum alloy is as follows, and
more or less will cause the following problems.
[1] Si 8 to 20%, more preferably 9 to 18%, and since less particles are formed at 8% or less,
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sufficient attenuation ability can not be obtained, and if it is 20% or more, coarse Si particle
formation Damping ability does not improve. [2] (i) 0.05 to 0.8% in total of at least one element
selected from the group consisting of Fe, Zr, V and Ti, more preferably 0.06 to 0.6% If it is less
than 0.05, the effect of refining the crystal is not sufficient. If it is more than 0.8%, coarse metal
compounds are formed and the damping ability and mechanical properties are impaired. (Ii) at
least one of the rare earth elements in total is 0.05-2%, more preferably L <0.06 to 1.5%, and if it
is 0.05 or less, the refining effect of the crystal is not sufficient If it is 2% or more, coarse metal
compounds are formed to impair the damping ability and mechanical properties. [3] If the total
content of Na and / or Sr is 0.1% or less, more preferably 0.05% or less, and 0.1% or more, the
refining effect is not recognized and the castability is impaired. (3) Sn of 0.005 to 0.1%, more
preferably 0.008 to 0.08%, not more than 0.005% is not sufficient to increase the viscosity of
grain boundaries, 0.1% or more In such a case, microsegregation is increased, damping ability is
not improved, and mechanical properties and corrosion resistance are degraded. In addition, in
the vibration damping aluminum alloy of the Al-3i system of the present invention, the average
grain diameter of the second phase particles (Si particles) is required to be 10 μm or less in the
crystal structure, and 10 μm or less. Thus, the interface of the second phase particles can be
increased to obtain a large damping capacity. The average particle diameter is more preferably 7
μm or less, still more preferably 5 μm or less. Further, in the vibration damping aluminum alloy
of the present invention, when Ni is added to Al, Ni particles are precipitated in Al as a matrix to
form a eutectic structure. Then, the interface of the second phase A 13 N x particles absorbs the
vibration to improve the damping capacity Q-1. When Sn is contained as in the fourth
embodiment, the precipitates are finely precipitated in the grain boundaries, the viscosity of the
grain boundaries is increased, and the damping ability Q- 'is improved. By the way, the weight
percentage of the above-mentioned Al-Ni-based vibration-proof aluminum alloy is as follows, and
if it is more or less than this, the following problems occur. [1] Ni 4 to 10%, more preferably 4.5
to 8%, and less particles being 4% or less, sufficient damping ability can not be obtained, and
10% or more coarse particles Due to the formation, the damping ability does not improve and the
mechanical properties deteriorate.
[2] (i) 0.05 to 0.8% in total of at least one element selected from the group consisting of Fe, Zr, V
and Ti, more preferably 0.06 to 0.6% . If it is less than 0.05, the effect of crystal refinement is not
sufficient, and if it is 0.8% or more, coarse metal compounds are formed to impair the damping
ability and mechanical properties. (Ii) If at least one of the rare earth elements in total is 0.05 to
2%, more preferably 0.06 to 1.5%, and if it is 0.05 or less, the refining effect of the crystal is not
sufficient; When it is at least%, coarse metal compounds are formed to impair the damping ability
and mechanical properties. (1) Sn is 0.005 to 0.1%, more preferably 0.008 to 0.08%, and it is not
sufficient to increase the viscosity of grain boundaries if it is 0.005% or less, 0.1% If it is above,
micro segregation will increase, damping ability will not be improved and mechanical properties
and corrosion resistance will be degraded. Further, in the vibration damping aluminum alloy of
the Al-Si system of the present invention, the average grain diameter of the second phase
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particles (Si particles) needs to be 10 μm or less in the crystal structure, and should be 10 μm
or less. As a result, the interface of the second phase particles can be increased, and a large
damping capacity can be obtained. The average particle diameter is more preferably 7 μm or
less, still more preferably 5 μm or less. Next, the Al-Si based or Al-Ni based vibration-damping
aluminum alloy of the present invention and Al (99, 5%) and a conventional Z n -Al based alloy
(trade name: Cosmar 2) Show the comparison. As apparent from the above table, the damping
ability Q- ′ ′ is higher than Al (99, 5%) in both the Al-5i-based and Al-Ni-based vibrationdamping aluminum alloys of the present invention, In addition, since the elastic modulus and the
density are substantially in the same range, the internal loss can be remarkably improved as
compared with the conventional example without lowering the light-weight rigidity and it is
extremely good as a material of an acoustic lens. Recognize. Recently, a Zn-Al alloy (trade name:
Cosmar Z) has attracted attention, but the one according to the present invention has a larger
damping capacity and is superior also in the specific elastic modulus proportional to the
propagation speed. Further, the 2n-Al based alloy has a problem of corrosion resistance, and
furthermore, its density is nearly doubled, so it is not suitable for weight reduction. Effect of the
Invention As the material of the acoustic lens according to the present invention uses the abovementioned specific Al-5i-based or Al-Ni-based anti-vibration aluminum alloy, the anti-vibration
effect is maintained while maintaining the rigidity. There is an effect that it can be made large,
and high quality products with less unnecessary radiation can be obtained stably and
inexpensively by the same operation as before.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a perspective view of an acoustic lens according to the present invention including a
conventional example, and FIG. 2 is a longitudinal sectional view of the acoustic lens.
In the figure, (1) indicates an acoustic lens. A long time ago
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