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JP2018519770

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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
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DESCRIPTION JP2018519770
Abstract: The present invention discloses an acoustic band pass filter and an acoustic sensing
device. The acoustic band pass filter includes at least two MEMS microphone chips and an ASIC
chip, and output signals of the MEMS microphone chips are combined and then processed in the
ASIC chip. [Selected figure] Figure 1
Acoustic band pass filter and acoustic sensing device
[0001]
The present invention relates to MEMS microphone technology, and more particularly to acoustic
band pass filters and acoustic sensing devices.
[0002]
In the prior art, MEMS (micro-electro-mechanical system) microphones are microphones
manufactured on the basis of MEMS technology.
In general, a MEMS microphone includes a MEMS microphone chip and an integrated circuit
(ASIC), and is used to convert received sound waves into audio electrical signals. Typically, MEMS
microphone chips have a resonant frequency on the high frequency side. The resonant frequency
is determined by factors such as a Helmholtz resonator composed of a front chamber (or a back
chamber), a resonant frequency of a vibrating membrane, and the like. In general, the MEMS
microphone chip has a narrow resonant frequency bandwidth. Also, due to manufacturing
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tolerances, the resonant frequency can not be determined. Therefore, in the prior art, the MEMS
microphone chip is not used directly to detect voice of a certain frequency.
[0003]
In the prior art, audio electrical signals are filtered by placing a filter in the ASIC. However, since
it is necessary to install an electronic member separately, the signal to noise ratio of the
microphone is degraded. In addition, these separately installed electronic members also generate
new product complexity. For example, on-chip capacitors, on-chip resistors, etc. must be
manufactured.
[0004]
One object of the present invention is to provide a new technical solution used in acoustic band
pass filters.
[0005]
According to an embodiment of the present invention, there is provided an acoustic band pass
filter comprising at least two MEMS microphone chips and an ASIC chip, wherein the output
signals of said MEMS microphone chips are combined and then processed in the ASIC chip.
[0006]
Preferably, each of the MEMS microphone chips is mounted in an acoustic hole of the substrate.
[0007]
Preferably, the device further comprises a metal casing for forming a back chamber of the MEMS
microphone chip, wherein the MEMS microphone chip is acoustically coupled by the back
chamber.
[0008]
Preferably, the filter further comprises a substrate, and the metal casing forms a closed back
chamber with the substrate.
[0009]
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Preferably, the output signals are combined in a series connection manner.
[0010]
Preferably, the resonant frequency of each MEMS microphone chip is adjusted by setting at least
one of the resonant frequency, the front chamber size and the acoustic aperture size of the
vibrating membrane of the MEMS microphone chip.
[0011]
According to an embodiment of the present invention, there is provided an acoustic sensing
device for sensing a sound wave, comprising an acoustic band pass filter according to the present
invention.
[0012]
Preferably, the sound wave comprises ultrasound.
Preferably, the acoustic sensing device is a microphone.
[0013]
In addition, although the person skilled in the art has many problems in the prior art, the
technical solutions in the embodiments or the claims of the present invention improve only one
or more problems, and the prior art or the prior art It should be understood that it is not
necessary to solve all the technical problems mentioned in the background art simultaneously.
It should be understood by those skilled in the art that what is not referred to in a single claim
should not be construed as limiting the claim.
[0014]
In the following, in order to make the other features of the present invention and their
advantages clear, an exemplary embodiment of the present invention will be described in detail
with reference to the drawings.
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[0015]
The accompanying drawings, which are incorporated in and constitute a part of the specification,
illustrate an embodiment of the invention and, together with the description, serve to interpret
the principles of the invention.
FIG. 5 schematically illustrates an acoustic band pass filter according to an embodiment of the
present invention.
It is a schematic curve figure for explaining the effect of the acoustic band pass filter by one
example.
It is a typical curve figure for explaining the effect of the acoustic band pass filter by another
example.
FIG. 2 shows an acoustic sensing device according to an embodiment of the present invention.
[0016]
Various exemplary embodiments of the invention will now be described in detail with reference
to the drawings.
It should be noted that the relative positions of parts and steps described in these examples,
formulas and numerical values do not limit the scope of the present invention unless specifically
described otherwise.
The following description of at least one exemplary embodiment is merely interpretive and does
not limit the invention and its application or use.
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[0017]
A detailed description of known techniques, methods and devices of the general engineer in such
field may be omitted, but, where appropriate, the techniques, methods and devices should be
considered as part of the specification.
[0018]
In all the examples illustrated and discussed herein, any specific numerical value is to be
interpreted as illustrative only and not as a limitation.
As such, other instances of the illustrative embodiments may have different numerical values.
It should be noted that similar symbols and alphabets indicate similar items in the following
figures, so if an item is defined in one figure, there is no need to consider it further in later
figures. Hereinafter, embodiments and examples of the present invention will be described with
reference to the drawings.
[0019]
FIG. 1 is a diagram showing an acoustic band pass filter according to an embodiment of the
present invention. As shown in FIG. 1, the acoustic band pass filter includes two MEMS
microphone chips 103, 104 and an ASIC chip 105. Those skilled in the art should understand
that the number of MEMS microphone chips is not limited to two and may be more than two.
[0020]
The output signals of the MEMS microphone chips 103 and 104 are coupled to an ASIC chip 105
via leads 106. The output signal may be coupled first via lead 106 and then input to ASIC chip
105, or may be coupled within the ASIC chip. Those skilled in the art may separate the ASIC chip
from the MEMS microphone chip, or may be built in the MEMS microphone chip. The combined
output signal is processed in the ASIC chip. For example, the processed signal is output to
another electronic device, such as a mobile phone, another member of a positioning device, or
the like.
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[0021]
In one example, the output signals are combined in a series connection manner to improve the
signal to noise ratio of the acoustic band pass filter.
[0022]
By combining the outputs of the two MEMS microphone chips, the resonant bandwidth of the
microphone chips can be increased.
For example, in FIG. 2, dotted line 202 shows the output curve of the first microphone chip, and
dotted line 203 shows the output curve of the second microphone chip. A solid line 201 shows a
combination of two output curves. At the top of the solid line 201, a pass band is formed.
[0023]
FIG. 3 shows an exemplary curve combining three MEMS microphone chips. The dotted line 302
shows the output curve of the first microphone chip, the dotted line 303 shows the output curve
of the second microphone chip, and the dotted line 304 shows the output curve of the second
microphone chip. A solid line 301 shows a combination of two output curves. At the top of the
solid line 301, a wide pass band is formed.
[0024]
The abscissas in FIGS. 2 and 3 represent the frequency and the ordinates represent the
sensitivity. The curves shown in FIGS. 2 and 3 are exemplary only and do not represent the
actual curve shape and it is not possible to read the actual values from said curves.
[0025]
On the other hand, filtering of the sound wave input can be realized by the passband. On the
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other hand, since such an acoustic band pass filter has excellent characteristics at high
frequencies, a microphone formed by such an acoustic band pass filter can have excellent voice
characteristics in a high frequency part.
[0026]
Preferably, as shown in FIG. 1, each of the MEMS microphone chips 103, 104 is attached to a
substrate 101 such as, for example, a PCB. The openings of the MEMS microphone chip
correspond to the acoustic holes 107, 108 of the substrate 101.
[0027]
Preferably, in FIG. 1, the acoustic bandpass filter further comprises a metal casing 102 for
forming the back chamber of the MEMS microphone chip. The MEMS microphone chips 103 and
104 are acoustically coupled through the back chamber. For example, the metal casing 102
forms a closed back chamber together with the substrate 101.
[0028]
Such acoustic coupling can further improve the sensitivity and / or the signal to noise ratio of the
acoustic band pass filter.
[0029]
For example, the resonant frequency of each MEMS microphone chip can be adjusted by setting
at least one of the resonant frequency, the front chamber size, and the acoustic aperture size of
the vibrating film of the MEMS microphone chip.
[0030]
FIG. 4 schematically illustrates an acoustic sensing device 401 according to one embodiment of
the present invention.
The acoustic sensing device 401 comprises an acoustic band pass filter 402 for sensing a sound
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wave according to the invention.
The acoustic band pass filter 402 is, for example, the acoustic band pass filter shown in FIG.
[0031]
In one example, such an acoustic sensing device can be used to detect ultrasound. For example,
the position of an object is measured by detecting an ultrasonic wave.
[0032]
In another example, such an acoustic sensing device can be used as a microphone. Such a
microphone has excellent high frequency characteristics because the acoustic band pass filter of
the present invention can strengthen the high frequency part of the MEMS microphone chip.
[0033]
While certain specific embodiments of the present invention have been described in detail by
way of illustration, those of ordinary skill in the art are only for the purpose of illustration and
should not limit the scope of the present invention. It should be understood that there is no.
Those skilled in the art should understand that the above embodiments can be modified without
departing from the scope and spirit of the present invention. The scope of the present invention
is limited by the appended claims.
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