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JP2003153396

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2003153396
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
photoacoustic transducer, and more particularly to a diaphragm structure thereof.
[0002]
2. Description of the Related Art A conventional acoustoelectric converter using light (hereinafter
referred to as a photoacoustic converter) is, for example, as shown in FIG. The light emitting
element 5 and the light receiving element 6 are fixed to the frame 4 and the light emitted from
the light emitting element 5 and reflected by the diaphragm 11 is received by the light receiving
element 6 so that the position of the diaphragm 11, that is Photo-acoustic conversion devices
that convert signals into signals are known.
[0003]
In the photoacoustic conversion device shown in FIG. 13, since the diaphragm is a flat plate, the
compliance of the diaphragm 11 can not be increased.
In order to improve the defects, the conventional photoacoustic transducer shown in FIG. 14 is
formed in a cross-sectional wave shape so that one valley and a peak are formed from the center
of the diaphragm 12 to the periphery, and the periphery is frame 4 The light emitting element 5
and the light receiving element 6 are further fixed to the frame 4.
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[0004]
Further, in the conventional photoacoustic conversion device shown in FIG. 15, a dome-shaped
reflection portion 13a is provided at the center of the diaphragm 13, a corrugation is formed
from the reflection portion 13a to the peripheral portion, and a support portion 13b provided in
the peripheral portion Is fixed to the frame 4, and the light emitting element 5 and the light
receiving element 6 are further fixed to the frame 4.
[0005]
Furthermore, in order to miniaturize the photoacoustic transducer and to convert sound to high
sensitivity, it is necessary to miniaturize the diaphragm and increase compliance.
The photoacoustic converter proposed in Japanese Patent Application No. 2001-184530 in
response to the request is shown in FIGS.
[0006]
That is, the photoacoustic conversion device using the diaphragm 14 in which the dome-shaped
reflection portion 14a is provided at the center and the corrugation is provided between the
reflection portion 14a and the support portion 14b is further improved. It cuts ¦ divides by light
etc. and forms the circular-arc-shaped slit 15a and the spiral-shaped slit 15b.
[0007]
The support 14 b of the diaphragm 14 is fixed to the frame 4.
Although illustration of the light emitting element and the light receiving element is omitted in
FIGS. 16 and 17, the light emitting element and the light receiving element are fixed to the frame
as in the above-described conventional example. The spiral slit 15b and the circular arc slit 15a
constitute the cantilevers 14c, 14c... And the substantially maximum outer side of the vibrating
portion, thereby improving the amplitude performance of the diaphragm 14 and improving the
performance of the photoacoustic transducer.
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[0008]
However, it is clear that the demand for miniaturization of the recent photoacoustic conversion
device is extremely large, and the diaphragm 14 formed in the dome shape shown in FIG. . In this
example, since the diaphragm 14 is partially cut off, as the diameter of the diaphragm 14
decreases, the ratio of the cantilever area increases and the area of the diaphragm 14 decreases,
and as a result, the pressure receiving area of the air pressure decreases. It can not be denied
that it is the structure which can not but be forced.
[0009]
Furthermore, although it is described in Japanese Patent Application No. 2001-184530 that it is
preferable to provide a ribbed structure on the outside of the vibrating portion adjacent to the
field stand where the cantilever 14c suspension is provided on a part of the diaphragm 14, The
shape of the plate 14 has a complicated three-dimensional structure, and as a matter of course,
there is also a problem that the manufacturing cost of the molding die of the diaphragm 14 is
likely to be high.
[0010]
SUMMARY OF THE INVENTION The present invention has been made to solve the above
problems, and the structure, particularly the shape, and the cantilever of the diaphragm proposed
by the applicant of the present application in the above-mentioned Japanese Patent Application
No. 2001-184530. It is an object of the present invention to provide a diaphragm of a
photoacoustic transducer suitable for mass production, while further improving the disposition
and shape of the suspension and improving the performance and enabling cost reduction.
[0011]
In order to solve the above problems, in order to obtain the shape of the cantilever suspension,
attention was paid not only to the shape of the cantilever suspension, but also to the position to
be disposed.
In that case, it is obvious that, in order to efficiently receive the vibration of the air, it is better for
the area of the vibrating portion of the diaphragm to be larger.
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[0012]
However, as in the prior art, in the method in which the cantilevered suspension is provided up
to the middle of the diaphragm in particular, if the diameter of the entire diaphragm is set small
except for the reflection part, the ratio occupied by the cantilevered suspension is inevitably
large. I have no choice.
[0013]
Therefore, a diaphragm made of a thin film, such as a film, in particular a vibrating portion of a
diaphragm having a small diameter, has a dome-shaped reflecting portion or a reflecting portion
which constitutes a vibrating plate as means for reducing compliance and vibrating the vibrating
portion. A flat portion extending in the horizontal direction in cross section toward the outer side
from the outer peripheral portion of the vibrating portion provided on the entire circumference,
and the flat portion is provided on the outer peripheral shape of the vibrating portion or on the
outer side of the reflecting portion In a state along the outer periphery of the vibrating portion,
slit processing is performed as thin as possible, and a cantilever suspension is disposed.
[0014]
Therefore, in the diaphragm structure of the photoacoustic conversion device according to the
present invention, the light emitting element and the light receiving element are opposed to the
reflecting portion formed in the vibrating portion of the diaphragm in which the vibrating
portion and the supporting portion are connected by a cantilever. In the photoacoustic
conversion device, which is disposed, emits light from the light emitting element to the reflecting
portion, receives the reflected light from the reflecting portion by the light receiving element, and
detects the position of the vibrating portion, the cantilever is the vibration The plate is formed by
slitting, and the space between the outer periphery of the vibrating portion and the inner
periphery of the cantilever and the inner periphery of the support portion and the outer
periphery of the cantilever are partitioned by the slitting. The cantilever is extended along an
outer periphery of the vibrating portion.
[0015]
Further, in the diaphragm structure, flat portions extending outward from the outer peripheral
edge of the reflective portion are provided on the entire circumference, and the cantilever is
disposed in a state along the outer edge of the reflective portion.
[0016]
Further, in the same diaphragm structure, a flat portion is provided with a sloped portion having
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a cross-sectional shape slant rising toward the outer side from the outer peripheral edge of the
reflection portion and further extending outward in the cross-sectional shape horizontally from
the outer periphery of the sloped portion. A portion is provided over the entire circumference,
and a cantilever is disposed on the flat portion along the outer peripheral edge of the vibrating
portion.
[0017]
Further, in the same diaphragm structure, a falling portion having a cross-sectional shape
perpendicular or substantially vertical is provided on the entire periphery of the outer peripheral
edge of the reflecting portion, and a cross-sectional shape horizontal direction further outward
from the outer peripheral portion of the falling portion. The flat portion extended to the bottom
is provided on the entire circumference, and the cantilever is disposed on the flat portion along
the outer periphery of the vibrating portion.
[0018]
Furthermore, in the diaphragm structure, a rising portion or a falling portion having a crosssectional shape perpendicular, oblique, or arc is provided on the outer peripheral edge of the
reflecting portion, and the outer peripheral edge of the rising portion or the falling portion A flat
portion extending in the horizontal direction of the cross-sectional shape is provided over the
entire circumference, and the cantilever is disposed on the flat portion in a state along the outer
peripheral shape of the vibrating portion.
[0019]
Embodiments of the present invention will be described with reference to the drawings.
The diaphragm in each example was manufactured by cutting and processing a resin film having
a thickness of about 9 μ to about 25 μ as it is in a flat plate shape, or manufactured by cutting
after heat and pressure molding.
[0020]
FIG. 1 is a plan view showing a diaphragm of a photoacoustic transducer according to a first
embodiment of the present invention, FIG. 2 is a cross sectional view showing the diaphragm,
and FIG. 3 is a photoacoustic transducer using the same diaphragm. It is sectional drawing which
shows.
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[0021]
The diaphragm 1 shown in the figure is a flat plate having a thickness of 15 μm and a diameter
of 6 mm, is slit, and the ring 3 is attached to the supporting portion 1b of the outer peripheral
portion by bonding. I was able to get it.
[0022]
That is, three arc-shaped inner slits 2a, 2a... And outer slits 2b, 2b... Are formed at equal intervals,
and the inner slit 2a and the outer slit 2b are connected by radial slits 2c to be surrounded by
slits. Cantilever 1c, 1c,... Are obtained, and this cantilever constitutes a suspension of the
vibrating portion 1a surrounded by the inner slits 2a, 2a,.
The dashed-dotted line described in the flat part in sectional drawing of FIG. 2 has shown the
position and width ¦ variety of a slit.
[0023]
Since the cantilever extends along the outer periphery of the vibrating portion in this manner, the
vibrating portion does not become too small even if the length of the cantilever is increased to
increase the compliance, and as a result, high-sensitivity and small-sized photoacoustic
conversion The diaphragm of the device is obtained.
[0024]
As shown in FIG. 3, the support portion 1b of the diaphragm 1 is fixed to the frame 4 via the ring
3, and the light emitting element 5 and the light receiving element 6 are further fixed to the
frame 4 to complete the photoacoustic conversion device.
The portion of the diaphragm 1 that reflects the light from the light emitting element 5 is
subjected to metal deposition.
[0025]
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FIG. 4 is a plan view showing a diaphragm of a photoacoustic transducer according to a second
embodiment of the present invention, FIG. 5 is a sectional view showing the diaphragm, and FIG.
6 is a photoacoustic transducer using the same diaphragm. It is sectional drawing which shows.
In this example, a film having a thickness of about 15μ was formed as shown in FIG. 5, and slit
processing was performed in the same manner as in the first example to obtain a diaphragm 7
having a desired amplitude characteristic.
[0026]
Hereinafter, details will be described. A flat portion is provided at the center, and a sloped
portion 7d of approximately 0.6 mm rising from the outer peripheral portion of the flat portion is
provided, and a flat portion flatter in the horizontal direction further outward than the upper end
of the sloped portion 7d. Is provided.
In the case of this embodiment, the flat portion provided outside the outer peripheral portion of
the sloped portion 7d is cut in a circle having a diameter of 6 mm.
[0027]
The width of this flat portion was 1 mm, and the same slit as in the first embodiment was
provided on this flat portion.
That is, three arc-shaped inner slits 2a, 2a... And outer slits 2b, 2b... Are formed at equal intervals,
and the inner slit 2a and the outer slit 2b are connected by radial slits 2c to be surrounded by
slits. Cantilever 7c having a width of about 0.2 mm is obtained, and this cantilever constitutes a
suspension of the vibrating portion 7a surrounded by the inner slits 2a, 2a.
[0028]
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The dashed-dotted line described in the flat part in sectional drawing of FIG. 5 has shown the
position and width ¦ variety of a slit.
In this embodiment, specifically, metal is deposited on the reflection surface side of the vibrating
portion after forming the diaphragm, and then slit processing is performed.
Then, as shown in FIG. 6, the support portion 7b of the diaphragm 1 is fixed to the frame 4 and
the light emitting element 5 and the light receiving element 6 are further fixed to the frame 4 to
complete the photoacoustic conversion device.
In this example, since the inclined surface is provided in the vibrating portion of the diaphragm,
the rigidity of the vibrating portion is enhanced, and the photoacoustic conversion characteristic
is further improved.
[0029]
FIG. 7 is a plan view showing a diaphragm of a photoacoustic transducer according to a third
embodiment of the present invention, FIG. 8 is a sectional view showing the diaphragm, and FIG.
9 is a photoacoustic transducer using the same diaphragm. It is sectional drawing which shows.
In this example, as shown in the cross-sectional view of FIG. 8, a reflecting portion 8a having a
diameter of 1.3 mm and a radius of curvature of 1.5 mm is provided at the center of the
diaphragm 8.
In the outermost periphery of this dome, a falling portion 8b of 0.5 mm in length is provided on
the entire outer periphery of the dome toward the lower side in the drawing, and further from
the lower end of the falling portion 8b to the outside in cross-sectional shape horizontal direction
A flat portion having an extended width of about 1.5 mm was provided on the entire
circumference, and this flat portion was cut by a circle having a diameter of 3 mm.
[0030]
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Slit processing is performed outside the falling portion 8ba provided on the outer periphery of
the dome along the outer periphery of the falling portion 8b at predetermined dimensional
intervals as shown in the plan view of FIG. Explaining in detail, in the case of this embodiment, it
is an arc shape (R1.225) which is roughly divided into three at a portion of a radius of 0.775 mm
as shown in a plan view further outside the dome outer periphery and consists of 4Ομ to 50μ.
Three inner slits 2a, 2a, ... were provided.
[0031]
Furthermore, outside the inner slits 2a, 2a, ..., a slit having a width (4Ομ to 50μ) of the same
width (4Ομ to 50μ) is given to a portion having a radius of 1.425 mm and a roughly divided
arc (R 1.425) A plurality of arc-shaped outer slits 2b, 2b,... Are provided, and slit processing is
performed so as to connect the outer slits 2b and the inner slits 2a with radial slits 2c as shown
in the drawing. The dashed-dotted line described in the flat part in sectional drawing of FIG. 8
has shown the position and width ¦ variety of a slit.
[0032]
A cantilever 8c is formed surrounded by the slit inner slit 2a, the outer slit 2b and the radial slit
2c, and the cantilever 8c serves as a suspension for supporting the reflecting portion 8a on the
supporting portion 8d.
[0033]
In the case of this embodiment, a suspension consisting of three cantilevers 8c is formed along
the outer periphery of the reflecting portion 8a, and the supporting portion 8d of the flat portion
provided on the outside of the outer slits 2b, 2b,. 8 has a function such as a sticking margin for
fixing the ring 8 to the ring 3, and a structure as shown in the cross-sectional view of the
explanatory view and supporting the reflecting portion 8a with cantilevers 8c and 8c having a
width of about 0.2 mm. It becomes.
[0034]
As shown in FIG. 9, the support 8d of the diaphragm 8 is fixed to the frame 4 via the ring 3, and
the light emitting element 5 and the light receiving element 6 are further fixed to the frame 4 to
complete the photoacoustic conversion device.
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In this embodiment, since the reflecting portion has a dome shape, the photoacoustic conversion
characteristic is further improved.
[0035]
FIG. 10 is a plan view showing a diaphragm of a photoacoustic transducer according to a fourth
embodiment of the present invention, FIG. 11 is a sectional view showing the diaphragm, and
FIG. 12 is a photoacoustic transducer using the same diaphragm. It is sectional drawing which
shows.
As shown in the figure, at the center of the diaphragm 9, a reflecting portion 9a having a
diameter of 1.3 mm and a curvature radius of 1.5 mm and having a dome shape is provided.
[0036]
This dome, that is, a sloped portion 9b which is inclined at an inclination of 45 ° from the outer
peripheral portion of the reflecting portion 9a, is provided, and the top end of this sloped portion
9b is set to about 3.2 mm in diameter. A section arc portion 9c with a radius of 0.24 mm is
provided on the tangent line, and a flat portion extending in the direction of 90 degrees outside
the section arc portion 9c, that is, in the horizontal direction shown in the figure.
[0037]
The diameter of the outer peripheral part of the cross-sectional circular arc part 9c provided at
the top end of the said slope part 9b is 4 mm.
In the case of this embodiment, the flat portion provided outside the outer peripheral portion of
the cross-sectional arc portion 9c is cut by a circle having a diameter of 6 mm. Accordingly, the
width of the flat end was 1 mm, and the flat portion was provided with a slit as shown in FIG.
[0038]
More specifically, three arc-shaped inner slits 2a, 2a,... Having a width of 40 .mu. To 50 .mu.,
Which are roughly divided into three, are provided at a radius of 2.215 mm, and roughly divided
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into three at a radius of 2.375 mm. Three outside slits 2b, 2b, ... with a width of 40μ to 50μ arc
are formed, and the inner slit 2a and the outer slit 2b are connected by the radial slit 2c to obtain
cantilevers 9d, 9d ... This cantilever constitutes a suspension of the vibrating portion surrounded
by the inner slits 2a, 2a.
[0039]
The flat portions provided on the outer side of the outer slits 2b, 2b,... Are support portions 9e
having a function as a sticking margin portion for fixing the diaphragm 9 to the ring 3 or the like.
As shown in the cross-sectional view of FIG. 11, the cantilever 9d having a width of about 0.2 mm
has a function of a suspension and supports the reflecting portion 9a and the sloped portion 9b.
The dashed-dotted line described in the flat part in sectional drawing of FIG. 11 has shown the
position and width ¦ variety of a slit.
[0040]
The back side of the diaphragms of the third and fourth embodiments, that is, the inner surface
of the dome is the reflection surface of the laser light, so metal reflection such as nickel or
aluminum is applied to the reflection surface side. It is It is also possible to perform metal
deposition only on the reflective portions 8a and 9a by masking. Although slit processing was
performed using a base plate, an excimer laser, a YAG laser, a carbon dioxide gas laser or the like
in these examples, it was possible to achieve the intended purpose with any of the lasers.
[0041]
The third and fourth embodiments are diaphragms in which the vibrating portion such as the
reflecting portion is three-dimensionally formed, but the present invention can be applied to a
planar diaphragm as in the first embodiment. It has been found.
[0042]
According to the diaphragm structure of the present invention, the cantilever-like suspension is
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inevitably disposed on the outside of the diaphragm.
And it is obvious that the outer peripheral part (outer side) is easier to take the length of the
cantilever than the inner peripheral part (inner side). In other words, it is possible to set the
compliance of the cantilever suspension higher, and as a result, it has an advantage that it has a
basic structure capable of obtaining a large amplitude and does not reduce the area of the
vibrating portion of the diaphragm significantly by the cantilever. Have.
[0043]
Furthermore, as in the third embodiment, when the area of the diaphragm is reduced as much as
possible, it is obvious that the dome of the reflecting portion 8a has the advantage of combining
the vibrating portion. At that time, there is no need to slit the reflective part, that is, the vibrating
part as in the prior art to arrange the suspension, and arrange the suspension on the outer
peripheral part of the vibrating part to miniaturize the diaphragm to the limit. Have the possible
benefits. Further, by providing the sloped portion 9b outside the reflection portion 9a as in the
fourth embodiment, it is natural that the strength of the diaphragm is increased and the surface
area of the vibration portion is increased.
[0044]
That is, the pressure receiving area of the sound pressure is increased with high strength, and the
strength of the outer peripheral portion of the diaphragm is obtained by providing the cross
section arc portion 9c or the rising portion or the falling portion on the outer peripheral portion
of the slope portion 9b. While making it possible to further increase the surface area of the
diaphragm. Therefore, it is possible to obtain a diaphragm having a structure with higher
sensitivity, higher sound quality, and easy amplitude, and it is possible to obtain a diaphragm
with higher performance.
[0045]
Further, although it has already been described in the above-mentioned Japanese Patent
Application No. 2001-184530 that deformation of the reflecting portion can be effectively
prevented by having a rib structure at the outermost peripheral portion of the reflecting portion,
the rising portion has a sectional shape at the dome outer peripheral portion. Of course, it is
preferable to provide the falling portion structure to enhance the rib structure rigidity.
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[0046]
However, when the reflection portion 9a is minimized, that is, when the diaphragm is minimized,
providing the rising portion in the oblique direction increases the size of the diaphragm, which is
a structure contrary to the minimization. It is clear.
[0047]
Therefore, by providing the vertical shaped standing portion on the dome outer periphery of the
reflecting portion, the enlargement of the dimension can be avoided.
However, although it is possible to provide a rising portion near the perpendicular to the dome
shape, that is, in the direction opposite to the upper direction as shown in the drawing, it has
been found that the film tends to break in film forming. It was also found that even if the film
could be molded, the film of the standing portion was likely to be thin in this direction and the rib
effect was halved.
[0048]
With respect to this defect, by providing the falling portion 8b on the dome outer peripheral
portion of the reflecting portion 8a as in the third embodiment, the film breakage is eliminated,
and a thickness satisfying the film thickness can be obtained, and the rib It was confirmed that
the effect could be sufficiently exhibited, and it was found that the effect could be exhibited to
improve the performance of the diaphragm.
[0049]
In addition, when there is a margin in size, naturally the rising portion in the diagonal direction is
effective.
Therefore, the form of the diaphragm shown in the fourth embodiment is a result that the
strength of the diaphragm is improved as well as the reinforcement of the reflection part, the film
formability is improved, and the strength of the -layer diaphragm is improved. Have an
advantage.
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[0050]
In addition, by adopting the structure as in the present invention, it is possible to carry out only
by lathe processing in the production of a film forming mold used for forming the diaphragm,
and the shape is also simple.
Therefore, there is an advantage that the processing cost is greatly reduced, the mold cost is
significantly reduced compared to the conventional example, and further, the fact that the slit
processed part is a flat part also contributes to the improvement of the processing accuracy of
the slit width. Quality and performance improvements are achieved with cost reduction.
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