close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2008245267

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
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 JP2008245267
The present invention provides a silicon microphone that is highly sensitive at least in places
where the sound pressure is small, and that has a large saturated sound pressure (wide dynamic
range) as compared to a conventional high sensitivity silicon microphone. SOLUTION: A plurality
of sub-silicon microphones 11A to 11D for outputting an electric signal having an amplitude
according to the sound pressure of the collected sound are accommodated in one housing, and
each of the sub-silicon microphones 11A. The sensitivities of ~ D are different from each other,
and are characterized by including a signal processing chip 20a that performs signal processing
based on the electrical signals output from each of the sub silicon microphones 11A ~ D.
[Selected figure] Figure 1
シリコンマイクロフォン
[0001]
The present invention relates to a silicon microphone.
[0002]
In a silicon microphone (silicon microphone), which is a device for converting sound pressure to
the amplitude of an electrical signal, when the amplitude is in a certain range or less, the sound
pressure is proportional to the amplitude, and the amplitude increases beyond that range. It is
known that even if the sound pressure increases, the amplitude does not follow and becomes
saturated.
18-04-2019
1
Here, the upper limit of the above-mentioned range is called saturation amplitude, and the sound
pressure at which the proportional relationship starts to collapse is called saturation sound
pressure. Also, the sound pressure range below the saturated sound pressure is called the
dynamic range.
[0003]
In the present specification, the term "sound pressure" is used in the sense of "amplitude value
corresponding to actual sound pressure" unless otherwise specified. That is, when the sound
wave that has reached the silicon microphone is detected by the silicon microphone having an
ideal characteristic that the sound pressure and the amplitude are always proportional, the
amplitude value of the electric signal output from the silicon microphone is I call it ". On the
other hand, the term "amplitude" is used in the sense of "an amplitude value corresponding to the
sound pressure detected by the silicon microphone". That is, the amplitude value of the electrical
signal actually output from the silicon microphone is called "amplitude".
[0004]
One of the other indicators indicating the characteristics of the silicon microphone is the
sensitivity indicating the rate of change of the amplitude with respect to the sound pressure. The
higher the sensitivity, the smaller the sound pressure can be picked up, while the amplitude
reaches the saturation amplitude with a relatively small sound pressure, so the saturated sound
pressure becomes smaller. For this reason, when using a silicon microphone, the necessary
saturated sound pressure (dynamic range) is determined according to the sound pressure of the
sound to be collected, and a silicon microphone having a sensitivity capable of realizing the
determined saturated sound pressure is selected It is necessary to manufacture.
[0005]
Patent Document 1 discloses a technique for realizing uniform amplitude characteristics in a
wide frequency range by using a plurality of special silicon microphones whose operating
frequency range is limited. JP 2001-169395 A
18-04-2019
2
[0006]
However, the sound pressure of the sound to be collected is not necessarily known when the
silicon microphone is selected or manufactured, and it is highly sensitive at least where the
sound pressure is small so that it can be used for a wide range of applications. It is required to
realize a silicon microphone having a large saturation sound pressure (wide dynamic range) as
compared with the high sensitivity silicon microphone of
[0007]
Therefore, one of the objects of the present invention is to provide a silicon microphone that has
high sensitivity at least where the sound pressure is small, and a large saturation sound pressure
(wide dynamic range) as compared to the conventional high sensitivity silicon microphone. It is
in.
[0008]
The present invention has been made to solve the above-mentioned problems, and the invention
according to claim 1 is characterized in that a plurality of electric signals having an amplitude
according to the sound pressure of the collected sound are output in one housing. Sub-silicon
microphones are accommodated, the sensitivity of each of the sub-silicon microphones is
different from each other, and the signal processing means for performing signal processing
based on the electric signal output from each of the sub-silicon microphones is included; It is.
According to this, since a plurality of sub-silicon microphones having different sensitivities are
accommodated in the above-mentioned housing, the sensitivity of the entire silicon microphone
becomes high due to the relatively high-sensitivity sub-silicon microphones at small sound
pressure.
Further, since the saturation sound pressure is the saturation sound pressure of the sub-silicon
microphone of the lowest sensitivity, the saturation sound pressure of the entire silicon
microphone is larger than that of the conventional high-sensitivity silicon microphone.
[0009]
A silicon microphone according to claim 2 of the present invention is characterized in that, in the
18-04-2019
3
silicon microphone according to claim 1, the plurality of sub-silicon microphones are integrally
formed on one chip. According to this, since a plurality of sub-silicon microphones can be formed
in a normal semiconductor manufacturing process applied to one semiconductor chip, the
manufacturing efficiency of the silicon microphone is improved.
[0010]
In the silicon microphone according to claim 3 of the present invention, in the silicon
microphone according to claim 1 or 2, the sensitivities of the sub-silicon microphones are
configured to be different from each other due to the difference in the size of the diaphragm. It is
characterized by Furthermore, a silicon microphone according to claim 4 of the present invention
is the silicon microphone according to any one of claims 1 to 3, characterized in that the signal
processing means is accommodated in the housing.
[0011]
A silicon microphone according to claim 5 of the present invention is the silicon microphone
according to any of claims 1 to 4, wherein the signal processing means is outputted from at least
a part of the plurality of sub-silicon microphones. And D. combining means for outputting a
combined signal obtained by combining signals based on electrical signals. According to this, the
combined signal can be used for signal processing.
[0012]
A silicon microphone according to a sixth aspect of the present invention is the silicon
microphone according to the fifth aspect, wherein the synthesizing means acquires sound
pressure information acquiring means for acquiring sound pressure information indicating the
sound pressure of the sound to be collected. And selecting at least one sub-silicon microphone
from the sub-silicon microphones, and switching the at least one sub-silicon microphone to be
selected according to sound pressure information acquired by the sound pressure information
acquiring unit. And microphone selection means. According to this, the silicon microphone can
generate the synthetic signal using only the sub silicon microphone selected according to the
sound pressure information of the sound to be collected.
18-04-2019
4
[0013]
A silicon microphone according to a seventh aspect of the present invention is the silicon
microphone according to the sixth aspect, wherein the combining means is selected when two or
more sub-silicon microphones are selected by the sub-silicon microphone selection means.
Combining the signals based on the electrical signals output from each of the two or more subsilicon microphones, and further dividing the amplitude of the signal obtained by combining by
the number of combined signals to generate the combined signal. It is characterized by According
to this, the combining means can output the combined signal with a constant amplitude that does
not depend on the number of sub-silicon microphones selected by the sub-silicon microphone
selecting means.
[0014]
In the silicon microphone according to claim 8 of the present invention, in the silicon
microphone according to claim 6 or 7, saturated sound pressure information for storing
saturated sound pressure information indicating the saturated sound pressure for each of the sub
silicon microphones. A storage unit, the sub-silicon microphone selection unit including sound
pressure information acquired by the sound pressure information acquisition unit, and saturated
sound pressure information of each of the sub silicon microphones stored in the saturated sound
pressure information storage unit; And switching the at least one sub-silicon microphone to be
selected. According to this, the sub silicon microphone selection means can select the sub silicon
microphone based on the saturated sound pressure information of each sub silicon microphone.
[0015]
The silicon microphone according to claim 9 of the present invention is the silicon microphone
according to claim 8, wherein the sub-silicon microphone selection means is indicated by
saturation sound pressure information stored in the saturation sound pressure information
storage means. One or more sub-silicon microphones whose saturation sound pressure is larger
than the sound pressure indicated by the sound pressure information acquired by the sound
pressure information acquiring means are selected. According to this, the sub silicon microphone
selection means can select the sub silicon microphone in which the sound pressure of the sound
to be collected is within the dynamic range.
18-04-2019
5
[0016]
Further, in the silicon microphone according to claim 10 of the present invention, in the silicon
microphone according to claim 8, the sound pressure information acquisition means is outputted
from a representative sub silicon microphone selected from among the respective sub silicon
microphones. Amplitude of the electric signal is obtained as the sound pressure information, and
the saturated sound pressure information storage means outputs the sound of the saturated
sound pressure for each of the sub silicon microphones when the representative The amplitude
of the electric signal to be stored is stored as the saturated sound pressure information, and the
sub-silicon microphone selection means is based on the amplitude indicated by the sound
pressure information and the amplitude indicated by each of the saturated sound pressure
information. Switching the one or more sub-silicon microphones to be selected To. According to
this, since both the sound pressure information and the saturated sound pressure information are
represented by the amplitude of the electric signal output from the representative sub-silicon
microphone, the sub-silicon microphone selection means The amplitude of the output electrical
signal can be used to select the sub-silicon microphone.
[0017]
The silicon microphone according to claim 11 of the present invention is the silicon microphone
according to claim 10, wherein the representative sub-silicon microphone is the least sensitive
sub-silicon microphone among the sub-silicon microphones. It is characterized by According to
this, since the representative sub-silicon microphone is the least sensitive sub-silicon microphone
among the sub-silicon microphones, the saturated sound pressure is larger than that of the other
sub-silicon microphones. Therefore, at sound pressure within the dynamic range of the other
sub-silicon microphones, the amplitude of the representative sub-silicon microphone is
proportional to the sound pressure. Therefore, the sub-silicon microphone selection means can
properly select the sub-silicon microphone.
[0018]
The silicon microphone according to claim 12 of the present invention is the silicon microphone
according to claim 6, wherein the combining unit switches the at least one sub-silicon
microphone to be selected by the sub-silicon microphone selecting unit, A signal based on an
electrical signal output from the at least one sub-silicon microphone selected before switching is
crossed with a signal based on an electrical signal output from the at least one sub-silicon
18-04-2019
6
microphone selected after switching It features that it fades and synthesizes. When the subsilicon microphone selected by the sub-silicon microphone selection unit is switched, the signal
may change suddenly and noise may be generated. However, according to the silicon
microphone, two cross fades for a predetermined time when switching. , The signal can be made
not to change suddenly.
[0019]
The silicon microphone according to claim 13 of the present invention is the silicon microphone
according to any of claims 5 to 12, wherein an electric signal output from each of at least a part
of the plurality of sub-silicon microphones And a pre-processing means for correcting the
amplitude of the signal by a correction value based on the sensitivity of the sub-silicon
microphone which has output the electric signal and a predetermined reference sensitivity. The
sub-silicon microphones have different sensitivities, so that the amplitudes of the output electric
signals are different even at the same sound pressure. Therefore, if it is used for signal
processing as it is, there is a possibility that appropriate signal processing can not be performed.
In this respect, according to the silicon microphone, since the amplitude of the electric signal
output from each sub-silicon microphone is corrected based on the reference sensitivity and the
sensitivity of each sub-silicon microphone, appropriate signal processing can be performed.
become.
[0020]
The silicon microphone according to claim 14 of the present invention is the silicon microphone
according to claim 13, wherein the predetermined reference sensitivity is a sensitivity of one of
the plurality of sub-silicon microphones, and the pre-synthesis processing The means is a
correction value based on the sensitivity of the sub-silicon microphone that has output the
electrical signal and the predetermined reference sensitivity, and is adjusted based on the
amplitude of the electrical signal output from the one sub-silicon microphone. The amplitude of
the electrical signal output from each of the sub silicon microphones other than the one sub
silicon microphone among the plurality of sub silicon microphones is corrected by the correction
value. According to this, the synthesis pre-processing means can correct the amplitude of the
electrical signal output from each sub-silicon microphone more accurately.
[0021]
18-04-2019
7
A silicon microphone according to a fifteenth aspect of the present invention is the silicon
microphone according to any of the first to fourth aspects, wherein in the housing, a partition
wall partitioning the inside into each of the plurality of sub-silicon microphones. And the signal
processing means determines the amplitude of the electrical signal output from each of at least a
portion of the plurality of sub-silicon microphones, the sensitivity of the sub-silicon microphone
which has output the electrical signal, and a predetermined reference. The pre-processing means
for correcting by the correction value based on the sensitivity and the electric signal output from
at least a part of each of the sub-silicon microphones, each electric signal after correction by the
pre-processing means By delaying by a predetermined amount and then synthesizing by a
predetermined synthesis method, Further comprising a directivity forming means for forming a
tropism, and characterized in that. According to this, since the directivity forming means uses the
electric signal corrected by the pre-combination processing means, it is possible to form
appropriate directivity using a plurality of sub-silicon microphones having different sensitivities
from one another. Become.
[0022]
A silicon microphone according to a sixteenth aspect of the present invention is the silicon
microphone according to any of the fifth to thirteenth aspects of the present invention, wherein
the electric signal output from any one of the plurality of sub-silicon microphones is used. And a
band characteristic control unit that corrects the amplitude with a correction value for each
frequency band corresponding to the sub-silicon microphone that has output the electric signal.
According to this, since the band characteristic control unit corrects the electric signal by the
correction value for each frequency band corresponding to the sub silicon microphone, the
frequency characteristic of the output of the silicon microphone is made flat, and the sound
represented by the output of the silicon microphone is It is possible to prevent the listener from
having an unobtrusive sound.
[0023]
The silicon microphone according to claim 17 of the present invention is the silicon microphone
according to any of claims 5 to 13, wherein the amplitude of the combined signal output by the
combining means is a frequency designated by the combining means. And a band characteristic
control unit that performs correction with a correction value for each band. According to this,
since the band characteristic control unit corrects the synthesized signal with the correction
value for each frequency band specified by the synthesizing means, the frequency characteristic
18-04-2019
8
of the output of the silicon microphone is made flat, and the sound represented by the output of
the silicon microphone is It is possible to prevent the listener from having an unobtrusive sound.
[0024]
Embodiments of the present invention will be described with reference to the drawings.
[0025]
First Embodiment FIG. 1A is a view showing a system configuration of a silicon microphone 1a
according to a first embodiment of the present invention.
The silicon microphone 1a is mounted on a small device such as a mobile phone or PDA
(Personal Digital Assistant), for example, and as shown in FIG. 2, a silicon microphone chip 10 by
MEMS (Micro Electro Mechanical Systems), A signal processing chip 20a is stored in one housing
30a as a multi-chip package.
[0026]
First, the structure of the silicon microphone 1a will be described. The silicon microphone chip
10 has a configuration in which four capacitor type sub silicon microphones 11A to 11D are
integrally formed. That is, as shown in FIGS. 3 and 4, the support layer 13 is formed on the
semiconductor substrate 12 made of, for example, single crystal silicon, and a plurality of hollow
holes are formed to penetrate the semiconductor substrate 12 and the support layer 13. 14A to
14D are formed, and an outer peripheral portion of a circular diaphragm (diaphragm) 15 and a
fixed plate 16 having a large number of through holes 17 is formed on the inner peripheral
portion of the support layer 13 in each of the cavity holes 14A to 14D. The diaphragm 15 and
the fixing plate 16 are supported in parallel so as to be bridged over the cavity holes 14A to 14D,
and a gap 18 is formed between the two. A capacitor-type sub-silicon microphone 11 is
configured by the diaphragm 15 and the fixing plate 16 in each of the hollow holes 14A to 14D.
In this case, as shown in FIG. 4, the sub-silicon microphones 11A to 11D have different
sensitivities by making the areas of the cavity holes 14A to 14D (in other words, the vibrating
portion of the diaphragm 15) different. It is formed.
[0027]
18-04-2019
9
Then, the silicon microphone chip 10 and a signal processing chip 20a incorporating a circuit for
driving the sub silicon microphones 11A to 11D of the silicon microphone chip 10 and
processing an output signal are stored in one housing 30a. A multichip package is configured.
[0028]
As shown in FIG. 2, the housing 30 a is provided with a substrate 31 having a side wall forming
an outer periphery with a mounting surface, and a lid provided to form a space above each subsilicon microphone 11 by being disposed on the side wall. It is composed of a body 32a.
The silicon microphone chip 10 mounted on the substrate 31 and the signal processing chip 20a
are electrically connected by a bonding wire 33, and the signal processing chip 20a is further
connected by a bonding wire (not shown) to a terminal (bottom end of the substrate) (Not shown)
is electrically connected. The electrical connection can also be obtained by making the substrate
a so-called multilayer wiring substrate and mounting the silicon microphone chip 10 and the
signal processing chip 20a thereon. The conductive layer in the multilayer wiring board functions
as a shield together with the lid 32a attached so as to cover the upper side of the chips 10 and
20a. Further, a hole 34a for taking in an audio signal is opened at the upper center of the signal
processing chip 20a of the lid 32a. The positions of the holes 34a are provided on the signal
processing chip 20a in order to prevent each sub silicon microphone 11 from the saliva of the
speaker or the like.
[0029]
The silicon microphone 1a configured in this way can connect the signal processing chip 20a to
an external circuit through the substrate 31 by mounting the terminal of the substrate 31 of the
housing 30a on the external substrate (not shown). ing. Then, a bias voltage is applied in advance
between the fixed plate 16 and the diaphragm 15, and when the diaphragm 15 vibrates due to
pressure fluctuation such as sound that has entered from the hole 34a of the lid 32a, the
diaphragm 15 is fixed with the diaphragm 15 The change in capacitance with the plate 16 is
taken out as an electrical signal.
[0030]
A method of manufacturing the silicon microphone chip 10 in the silicon microphone 1a
configured in this way will be described. First, as shown in FIG. 5A, for example, CVD (Chemical
18-04-2019
10
Vapor Deposition) or the like on the surface of the semiconductor substrate 111. A silicon oxide
layer (SiO 2) 112 to be a sacrificial layer is formed by the thin film formation technique
described above, and a polysilicon layer 113 to be a diaphragm is sequentially stacked thereon.
[0031]
Then, a resist pattern 114 is formed on the polysilicon layer 113, and the polysilicon layer 113 is
etched using this as a mask to form a plurality of circular diaphragms 15 having different areas.
[0032]
Next, as shown in FIG. 5B, a silicon oxide layer 115 serving as a spacer and a polysilicon layer
116 serving as a fixing plate are sequentially stacked on the whole, and these diaphragms 15 are
covered on the polysilicon layer 116. Resist pattern 117 is formed, and polysilicon layer 116 is
etched using this as a mask to form circular fixed plate 16 having through holes 17.
[0033]
Then, a resist pattern (not shown) is formed on the lower surface of the semiconductor substrate
111 leaving portions to become the cavity holes 14A to 14D, and deep etching is performed by
deep RIE (Reactive Ion Etching) using this as a mask. The central portion of the semiconductor
substrate 111 is removed until it reaches the interface with the silicon oxide layer 112 as shown
in FIG. 1) to form the semiconductor substrate 12 having a portion corresponding to the
diaphragm.
[0034]
Then, a resist pattern 118 covering the silicon oxide layer 115 is formed to expose the region of
the fixing plate 16 in which the through holes 17 are formed, and the whole is immersed in an
etchant such as hydrofluoric acid to perform wet etching. The silicon oxide layer 115 between
the fixing plate 16 and the diaphragm 15 is removed in the area where the through holes 17 are
formed, and the silicon oxide layer 112 in the portion in contact with the diaphragm 15 is also
removed. Thus, the fixing plate 16 and the diaphragm 15 form the gap 18 in the support layer
13 (composed of the silicon oxide layers 112 and 115) on the semiconductor substrate 12
having the cavity holes 14A to 14D as shown in FIG. The open and supported silicon microphone
chip 10 is manufactured.
[0035]
18-04-2019
11
As mentioned above, although the example of the silicon microphone chip 10 which integrally
formed several sub silicon microphones 11A-11D in one semiconductor substrate was shown, as
shown in FIG. 6, the sub silicon microphones 11A-11D from which a sensitivity differs mutually
each The sub-silicon microphone chips 10A to 10D may be formed on different semiconductor
substrates, and the plurality of sub-silicon microphone chips 10A to 10D may be housed in one
housing 30a.
In FIG. 6, the sub silicon microphone chip 10 provided at a position far from the signal
processing chip 20a is connected to the signal processing chip 20a via a terminal (not shown) of
the side wall of the substrate 31 of the housing 30a. .
[0036]
Next, referring back to FIG. 1, the signal processing performed in the signal processing chip 20a
will be described.
As shown in FIG. 1B, the signal processing chip 20a includes an A / D (Analogue / Digital)
conversion unit 21 and a wide DR (Dynamic Range: dynamic range) processing unit 22a.
[0037]
As described above, the diaphragms 15 of the respective sub-silicon microphones 11 are
configured to vibrate due to the arriving sound, and the capacitance between the diaphragms 15
and the fixed plate 16 changes with the vibration.
Each sub-silicon microphone 11 outputs an electrical signal indicating the change in capacitance.
[0038]
Here, the amplitude of the electric signal output from each sub-silicon microphone 11 is a value
according to the sound pressure of the collected sound (the amount of vibration of the
diaphragm 15 shown in FIG. 3) in principle, as described above The sound pressure and the
amplitude are proportional when the amplitude is in the range below the saturation amplitude,
18-04-2019
12
and become non-proportional when the amplitude increases beyond the range.
[0039]
Here, the saturation amplitudes of the respective sub-silicon microphones 11 are the same, while
the proportional coefficients (rate of change of amplitude with respect to sound pressure:
sensitivity) are different from each other in a range in which sound pressure and amplitude are
proportional.
Therefore, the saturated sound pressure, which is the sound pressure at which the proportional
relationship starts to break, is different for each sub silicon microphone 11.
[0040]
The saturated sound pressures of the sub silicon microphones 11A to 11D are hereinafter
referred to as PA to PD, respectively.
Also, the sensitivities of the sub silicon microphones 11A to 11D are respectively SA to SD.
Further, it is assumed that the sensitivity becomes worse in the order of the sub silicon
microphones 11A, 11B, 11C, 11D (that is, SA> SB> SC> SD).
[0041]
The sensitivity of each sub-silicon microphone 11 should be different from each other in at least
one of the area of diaphragm 15, the thickness of diaphragm 15, or the internal stress of
diaphragm 15 (stress against contraction and expansion caused by vibration). Are preferably
different from one another. For example, as the area of the diaphragm 15 is larger, the sensitivity
of the sub silicon microphone 11 is higher. Further, the thicker the diaphragm 15, the lower the
sensitivity of the sub silicon microphone 11. Furthermore, as the internal stress of the diaphragm
15 is larger, the sensitivity of the sub silicon microphone 11 is lower.
18-04-2019
13
[0042]
The signal processing chip 20 a performs signal processing based on the electrical signal output
from each of the sub silicon microphones 11. Specifically, the A / D converter 21 first samples
the amplitude of the electric signal (analog signal) output from each sub-silicon microphone 11
at a predetermined time interval to thereby indicate the electric signal indicating the amplitude
as a digital value. It converts into (digital signal) and outputs it to the wide DR processing unit
22a.
[0043]
The wide DR processing unit 22a realizes high sensitivity at least at a small sound pressure by
using the electric signal output from each of the sub silicon microphones 11, and the saturation
sound pressure (larger than that of the conventional high sensitivity silicon microphone) Achieve
a wide dynamic range). Specifically, the wide DR processing unit 22 a acquires, via the A / D
conversion unit 21, the electrical signals output from the respective sub silicon microphones 11.
Then, based on the acquired plurality of electrical signals, signal processing (combination
processing) for expanding the dynamic range is performed, and the signal is output to the
outside of the silicon microphone 1a.
[0044]
The details of the processing of the wide DR processing unit 22a will be described below. FIG. 7
is a schematic block diagram showing functional blocks of the wide DR processing unit 22a. As
shown in the figure, the wide DR processing unit 22a includes a combining control unit 221a,
three combining pre-processing units 226a (226aA to 226aC), and a combining unit 227a.
Further, the combination control unit 221 a includes an amplitude information acquisition unit
222, a selection unit 223 a, a saturation amplitude information storage unit 224, and a cross
fade coefficient generation unit 225. The details will be described below.
[0045]
First, each combining pre-processing unit 226a will be described. Since the sensitivities of the
18-04-2019
14
respective sub-silicon microphones 11 are different from each other, the amplitudes of the
electric signals output from the respective sub-silicon microphones 11 are different even if
sounds of the same sound pressure arrive. Therefore, each synthesis pre-processing unit 226a
corrects the amplitude of the electrical signal output from the corresponding sub-silicon
microphone 11 based on the sensitivity of the sub-silicon microphone 11 that has output the
electrical signal and a predetermined reference sensitivity. Correct by
[0046]
Here, each synthesis pre-processing unit 226a sets the amplitude of the electric signal output
from each of the sub-silicon microphones 11A to 11C to a predetermined reference sensitivity
(here, the sensitivity SD of the sub-silicon microphone 11D is the reference sensitivity. Adjust to
the amplitude according to). In a specific example, the synthesis pre-processing unit 226aA
corrects the amplitude of the electrical signal output from the sub silicon microphone 11A based
on the sensitivity SA of the sub silicon microphone 11A and the predetermined reference
sensitivity SD. Correct by SA). That is, the amplitude of the electrical signal output from the sub
silicon microphone 11A is multiplied by SD / SA. The same applies to the other combining preprocessing units 226a. The electric signal that has been corrected in this way is input to the
combining unit 227a.
[0047]
Next, the amplitude information acquisition unit 222 of the combination control unit 221a
acquires sound pressure information indicating the sound pressure of the sound to be collected.
Specifically, a representative sub-silicon microphone 11 selected from the sub-silicon
microphones 11 (the sub-silicon microphone 11 having the lowest sensitivity among the subsilicon microphones 11). ここではサブシリコンマイク11D。 The amplitude of the envelope of
the electrical signal output from the above is acquired as the sound pressure information.
[0048]
The saturation amplitude information storage unit 224 stores, for each sub-silicon microphone
11, saturation sound pressure information indicating the saturation sound pressure. Specifically,
for each sub-silicon microphone 11, the amplitude of the electrical signal output when the
representative sub-silicon microphone 11 picks up the sound of the saturated sound pressure is
18-04-2019
15
stored as saturated sound pressure information.
[0049]
The saturated sound pressure information will be more specifically described with reference to
FIG. FIG. 8 is a view showing the relationship between the sound pressure and the amplitude of
the electric signal output from each of the sub-silicon microphones 11. As shown in FIG. 8, the
proportional relationship between the sound pressure and the amplitude gradually collapses as
the sound pressure increases. The saturated sound pressure is appropriately determined by the
value at which the proportional relationship starts to break down. FIG. 8 shows the saturated
sound pressures PA, PB, and PC thus determined.
[0050]
The saturated sound pressure information of the sub silicon microphone 11A is the amplitude
THA of the electric signal output when the sound of the saturated sound pressure PA is picked up
by the sub silicon microphone 11D. The same applies to the amplitudes THB and THC.
[0051]
The selection unit 223a selects one sub silicon microphone 11 from among the sub silicon
microphones 11, and switches the sub silicon microphone 11 to be selected according to the
sound pressure information acquired by the amplitude information acquisition unit 222. That is,
the sub-silicon microphone 11 whose saturation sound pressure is larger than the sound
pressure corresponding to the amplitude indicated by the sound pressure information is selected.
[0052]
Specifically, the amplitude indicated by the sound pressure information acquired by the
amplitude information acquiring unit 222 is compared with the amplitude indicated by each of
the saturated sound pressure information stored in the saturation amplitude information storage
unit 224, and the comparison is made. The sub silicon microphone 11 to be selected is switched
based on the result.
18-04-2019
16
[0053]
The process of the selection unit 223a will be described using a specific example, with reference
to FIG. 8 again.
In the example shown in the figure, the selecting unit 223a has an amplitude (A) indicated by the
sound pressure information. ) Is compared to THA, THB, and THC. Then, when A <THA, the
selection unit 223a selects the sub silicon microphone 11A. When THA ≦ A <THB, the selection
unit 223a selects the sub silicon microphone 11B. Furthermore, when THB ≦ A <THC, the
selection unit 223a selects the sub silicon microphone 11C. Then, if THC ≦ A, the selection unit
223a selects the sub silicon microphone 11D.
[0054]
The combining unit 227a normally outputs a signal based on the electrical signal output from the
one sub silicon microphone 11 selected by the selecting unit 223a as it is (this output is also an
aspect of the combining result. ) Switches the sub-silicon microphone 11 selected by the
selection unit 223a, and outputs a composite signal formed by combining signals based on
electric signals output from the respective sub-silicon microphones 11 before and after switching
for a predetermined time. . That is, a signal based on the electric signal output from the subsilicon microphone 11 selected before switching (the sub-silicon microphones 11A to 11C are
electric signals after processing by the combination preprocessing unit 226a). The electrical
signal itself to be output for the sub silicon microphone 11D. Hereinafter, it will be referred to as
an electrical signal S1. And the signal based on the electrical signal output from the sub silicon
microphone 11 selected after switching (same as above). Hereinafter, it will be referred to as an
electrical signal S2. And crossfading while combining.
[0055]
FIG. 9 is a diagram illustrating a specific example of the cross fade. In the example shown in the
figure, the combining unit 227a performs cross fading between time t1 and time t2. That is, as
shown in the figure, between time t1 and time t2, the combining unit 227a acquires both the
electrical signal S1 and the electrical signal S2, and outputs the combined signal. At this time, the
amplitude of the electric signal S1 is gradually decreased according to the time attenuation rate,
18-04-2019
17
while the amplitude of the electric signal S2 is gradually increased according to the time
amplification rate. The combining unit 227a thus realizes the cross fade.
[0056]
The crossfade coefficient generation unit 225 generates a crossfade coefficient including the
time attenuation factor of the electric signal S1 and the time amplification ratio of the electric
signal S2 at the time of switching by the selection unit 223a in order to realize the abovementioned cross fade. Input to the part 227a.
[0057]
As described above, according to the present embodiment, since a plurality of sub-silicon
microphones 11 having different sensitivities are prepared, high sensitivity as the entire silicon
microphone 1a can be achieved by the relatively high sensitivity sub-silicon microphone 11 in
places where the sound pressure is small. It becomes.
Further, since the saturation sound pressure is the saturation sound pressure of the sub-silicon
microphone 11 with the lowest sensitivity, the saturation sound pressure of the entire silicon
microphone 1a is larger than that of the conventional high-sensitivity silicon microphone.
[0058]
Further, at least one of the plurality of sub-silicon microphones 11 having different sensitivities
can be used for signal processing because at least one of the sub-silicon microphones 11 selected
according to the sound pressure information of the sound to be collected can be provided. In a
place where is small, high sensitivity sub silicon microphone 11 can be used. On the other hand,
since the low sensitivity sub-silicon microphone 11 can be used where the sound pressure is
large, the silicon microphone 1a has a large saturated sound pressure (wide dynamic range)
compared to the conventional high sensitivity silicon microphone .
[0059]
In addition, when the sub-silicon microphone 11 selected by the selection unit 223a is switched,
the electric signal may change suddenly and noise may be generated. However, according to the
silicon microphone 1a, cross-fading is performed at the time of switching. You can make sure
18-04-2019
18
that the signal does not change suddenly.
[0060]
Further, the selection unit 223 a can determine at least one sub silicon microphone 11 to be
selected based on the saturated sound pressure information of each sub silicon microphone 11.
Furthermore, the selection unit 223a can select the sub silicon microphone 11 whose sound
pressure is within the dynamic range of the sound to be collected.
[0061]
Specifically, the value is represented by the amplitude of the electrical signal output from
representative sub-silicon microphone 11 for both the sound pressure information and the
saturated sound pressure information, so that selection unit 223 a outputs the signal from
representative sub-silicon microphone 11 The amplitude of the electrical signal being generated
can be used to select the at least one sub-silicon microphone 11.
[0062]
Furthermore, since the representative sub-silicon microphone 11 is the sub-silicon microphone
11 having the lowest sensitivity among the sub-silicon microphones 11, the saturated sound
pressure is larger than that of the other sub-silicon microphones 11.
Therefore, although the sound pressure in the dynamic range of the other sub-silicon
microphones 11 is somewhat unreliable in the bass pressure region, the amplitude of the
representative sub-silicon microphone 11 can be regarded as substantially proportional to the
sound pressure. Therefore, the selection unit 223a can appropriately select at least one sub
silicon microphone 11.
[0063]
Further, since the respective sub-silicon microphones 11 have different sensitivities, the
18-04-2019
19
amplitudes of the electric signals to be output are different even at the same sound pressure. For
this reason, if it is used for signal processing as it is, when the sub-silicon microphone 11
selected by the sub-silicon microphone selection unit is switched, discontinuity of amplitude
occurs. In this respect, according to the silicon microphone 1a, since the amplitude of the electric
signal output from each sub silicon microphone 11 is corrected based on the reference
sensitivity and the sensitivity of each sub silicon microphone 11, the occurrence of the
discontinuity is prevented. can do.
[0064]
Second Embodiment FIG. 10 is a schematic block diagram showing functional blocks of a wide
DR processing unit 22b included in a silicon microphone 1b according to a second embodiment
of the present invention. The silicon microphone 1b is obtained by replacing the wide DR
processing unit 22a with the wide DR processing unit 22b in the silicon microphone 1a.
[0065]
As shown in FIG. 10, the wide DR processing unit 22b is configured to include a combining unit
227b. The synthesizing unit 227 b is a signal based on the electric signal output from each sub
silicon microphone 11 (here, the electric signal itself output from each sub silicon microphone
11). ) To output a synthesized signal to the outside of the silicon microphone 1b.
[0066]
A specific synthesizing method by the synthesizing unit 227b will be described with reference to
FIG. FIG. 11 shows the relationship between the sound pressure and the amplitude of the electric
signal output from each of the sub-silicon microphones 11, and also shows the relationship
between the sound pressure and the amplitude of a combined signal synthesized by two types of
combining methods.
[0067]
Note that FIG. 11 shows an ideal example in which the sound pressure increases to reach the
18-04-2019
20
saturation amplitude while the sound pressure and the amplitude maintain a proportional
relationship for the sake of simplicity. As shown in FIG. 8, as the sound pressure increases, the
proportional relationship between the sound pressure and the amplitude gradually breaks down.
Also, the bass pressure region of the low sensitivity sub-silicon microphone 11 is somewhat
unreliable.
[0068]
The first type of synthesis method is simple addition. In this example, the combining unit 227b
obtains a combined signal by adding the amplitudes of the respective electric signals by an adder
(not shown) ("simple addition" in FIG. 11).
[0069]
The second type of synthesis method is the square root of the sum of squares. In this example,
the combining unit 227b squares the amplitudes of the respective electric signals by a multiplier
(not shown) and adds them, and then takes the square root to obtain a combined signal (see
“Sum of Squares Root of FIG. ").
[0070]
The composite signal may be obtained as follows. In this example, sound pressure (hereinafter,
"sound pressure" is used in the meaning of "actual sound pressure" in this paragraph. The value
of “actual sound pressure” is a value having a positive or negative sign, unlike “amplitude
value corresponding to the actual sound pressure”. Consider the sign of). That is, the sound
pressure of the sound wave detected by the sub-silicon microphone 11 vibrates with positive and
negative values centering on the amplitude value 0. However, when the square sum root is
calculated as described above, the sign due to this vibration is canceled You Therefore, a series of
processes shown in the following (1) to (7) are performed to obtain a synthesized signal. As a
result, the synthesized signal can be output while maintaining the code. (1) Hold the sign of each
sound pressure. (2) Each sound pressure except the sign is squared. (3) Add the code held in (1)
to the square value of each sound pressure. (4) Each sound pressure with a sign is added to
obtain an added value. (5) Hold the sign of the added value. (6) Find the square root of the added
value excluding the sign. (7) The code held in (5) is added to the square root obtained in (6) and
output as a combined signal.
18-04-2019
21
[0071]
The high sensitivity at least where the sound pressure is small and the saturation sound pressure
(wide dynamic range) which is larger than that of the conventional high sensitivity silicon
microphone can be realized by any of the above-described synthesis methods.
[0072]
As described above, according to the present embodiment as well, a plurality of sub-silicon
microphones 11 having different sensitivities are prepared. Therefore, the relatively highsensitivity sub-silicon microphone 11 achieves high sensitivity as the entire silicon microphone
1b at locations where the sound pressure is small. Become.
Further, since the saturation sound pressure is the saturation sound pressure of the sub-silicon
microphone 11 with the lowest sensitivity, the saturation sound pressure of the entire silicon
microphone 1 b is larger than that of the conventional high-sensitivity silicon microphone.
[0073]
That is, since the sensitivity of the synthesized signal generated by the synthesizing unit 227b is
relatively high sensitivity sub-silicon microphone 11A when the sound pressure is small, each of
the plurality of sub-silicon microphones 11 further outputs the synthesized signal. This is a
relatively high value because it is a composite of the electrical signals. Further, the saturation
sound pressure of the synthesized signal is the saturation sound pressure of the sub-silicon
microphone 11D of the lowest sensitivity. Therefore, in the place where the sound pressure is
small, the entire silicon microphone 1b has high sensitivity. Further, the saturated sound
pressure of the silicon microphone 1b as a whole is larger than that of the conventional high
sensitivity silicon microphone.
[0074]
The combining preprocessing units 226aA to 226aC described in the first embodiment may be
provided between the combining unit 227b and the sub-silicon microphones 11A to 11C.
18-04-2019
22
[0075]
Since the respective sub-silicon microphones 11 have different sensitivities, the amplitudes of the
output electric signals are different even at the same sound pressure.
Therefore, if it is used for signal processing as it is, there is a possibility that the synthesis result
of the synthesis unit 227b may not be appropriate. In this respect, as described above, since the
amplitudes of the electric signals output from the respective sub-silicon microphones 11 are
corrected based on the reference sensitivity and the sensitivity of the respective sub-silicon
microphones 11, appropriate synthesis results are obtained Becomes possible.
[0076]
Third Embodiment FIG. 12 is a schematic block diagram showing functional blocks of a wide DR
processing unit 22c included in a silicon microphone 1c according to a third embodiment of the
present invention. The silicon microphone 1c is obtained by replacing the wide DR processing
unit 22a with the wide DR processing unit 22c in the silicon microphone 1a.
[0077]
As shown in FIG. 12, the wide DR processing unit 22c replaces the combining control unit 221a
and the combining unit 227a in the wide DR processing unit 22a with the combining control unit
221b and the combining unit 227c. The combination control unit 221b is the combination
control unit 221a in which the selection unit 223a is replaced with a selection unit 223b. The
differences between the selection unit 223a and the synthesis unit 227a will be described below
for each of the selection unit 223b and the synthesis unit 227c.
[0078]
Unlike the selecting unit 223a, the selecting unit 223b selects at least one sub silicon
microphone 11 from among the respective sub silicon microphones 11, and selects according to
the sound pressure information acquired by the amplitude information acquiring unit 222. At
least one sub silicon microphone 11 is switched.
18-04-2019
23
[0079]
The process of the selection unit 223b will be described using a specific example, with reference
to FIG. 8 again.
In the example shown in the figure, the selection unit 223b compares the amplitude A indicated
by the sound pressure information with THA, THB, and THC. When A <THA, the selection unit
223b selects the sub silicon microphones 11A to 11D. When THA ≦ A <THB, the selection unit
223b selects the sub silicon microphones 11B to 11D. Furthermore, when THB ≦ A <THC, the
selection unit 223b selects the sub silicon microphones 11C and 11D. When THC ≦ A, the
selection unit 223b selects the sub silicon microphone 11D.
[0080]
The synthesis unit 227 c includes three adders 228 (228 A to 228 C), three amplitude correction
units 229 (229 A to 229 C), and a cross fade unit 230.
[0081]
Each adder 228 combines the electrical signals output from each sub silicon microphone 11
selected by the selection unit 223 b when two or more sub silicon microphones 11 are selected
by the selection unit 223 b.
Here, the adder 228C outputs a composite signal obtained by combining signals based on the
electrical signals output from the sub-silicon microphones 11C and 11D. Similarly, the adder
228B outputs a composite signal formed by combining the signals based on the electrical signals
respectively output from the sub-silicon microphones 11B to 11D and the sub-silicon
microphones 11A to 11D.
[0082]
Each amplitude correction unit 229 divides the amplitude of the signal obtained by the
combination of each adder 228 by the number of the synthesized signals when two or more subsilicon microphones are selected by the selection unit 223 b.
18-04-2019
24
[0083]
The cross fading unit 230 of the combining unit 227 c selects one of the output signals of each
of the amplitude correction units 229 or the sub silicon microphone 11 D according to the
selection of the selection unit 223 b.
Then, although the selected output signal is normally output as it is, when the sub-silicon
microphone 11 selected by the selection unit 223b is switched, the output signal selected before
switching and the output signal selected after switching are cross-faded While synthesizing. The
specific method of the cross fade is the same as that of the synthesis unit 227a.
[0084]
As described above, according to the present embodiment as well, a plurality of sub-silicon
microphones 11 having different sensitivities are prepared. Therefore, the relatively highsensitivity sub-silicon microphone 11 achieves high sensitivity as the entire silicon microphone 1
c at locations where the sound pressure is small. Become. Further, since the saturation sound
pressure is the saturation sound pressure of the sub-silicon microphone 11 with the lowest
sensitivity, the saturation sound pressure of the entire silicon microphone 1 c is larger than that
of the conventional high-sensitivity silicon microphone.
[0085]
Also, the silicon microphone 1 c can generate a synthesized signal using only the sub silicon
microphone 11 selected according to the sound pressure information of the sound to be
collected. Furthermore, the combining unit 227c can output a combined signal with a constant
amplitude that does not depend on the number of sub-silicon microphones 11 selected by the
selecting unit 223b.
[0086]
In addition, when at least one sub-silicon microphone 11 selected by the selection unit 223b
switches, the composite signal may change suddenly and noise may occur. However, according to
the silicon microphone 1c, cross-fading is performed at the time of switching. , And the
composite signal can be prevented from changing suddenly.
18-04-2019
25
[0087]
Also, since the outputs of the usable (non-saturated) sub-silicon microphones 11 are averaged by
the combination of the respective adders 228, particularly at low sound pressure, the
combination by the respective adders 228 is not performed. As compared to the case, random
noise will be reduced.
[0088]
Fourth Embodiment FIG. 13 is a schematic block diagram showing functional blocks of a wide DR
processing unit 22 d included in a silicon microphone 1 d according to a fourth embodiment of
the present invention.
The silicon microphone 1d is obtained by replacing the wide DR processing unit 22c with the
wide DR processing unit 22d in the silicon microphone 1c.
[0089]
As shown in FIG. 13, the configuration of the wide DR processing unit 22 d is such that the precombination processing units 226 aA to 226 a C in the wide DR processing unit 22 c are
replaced with combining pre-processing units 226 bA to 226 b C, respectively.
Hereinafter, these differences will be described.
[0090]
Each synthesis pre-processing unit 226b performs an amplitude correction process for
equalizing the amplitudes of the electric signals output from the respective sub-silicon
microphones 11 in the same manner as each synthesis pre-processing unit 226a. The accuracy is
enhanced by using the sound pressure information (amplitude of the electric signal output from
the sub silicon microphone 11D) output by the signal 222. The process will be described in detail
below.
18-04-2019
26
[0091]
FIG. 14 is a diagram showing an internal configuration of the pre-combination processing unit
226bA. As shown in the figure, the pre-combination processing unit 226bA includes an amplifier
2261A, an amplitude detection unit 2262A, and a correction value determination unit 2263A.
Here, although the description is made by taking up the pre-combination processing unit 226bA,
the processes of the combination pre-processing units 226bB and 226bC are the same.
[0092]
Amplifier 2261A receives an input of an electrical signal from sub-silicon microphone 11A. Then,
amplification is performed at an amplification factor according to a correction value determined
by a correction value determination unit 2263A described later, and amplification is performed
to an adder 228A of a combining unit 227c. The amplitude detection unit 2262A detects the
amplitude of the electrical signal output from the amplifier 2261A, and outputs the amplitude to
the correction value determination unit 2263A.
[0093]
The correction value determination unit 2263A acquires a correction value (SD / SA) based on
the sensitivity SA of the sub silicon microphone 11A and the predetermined reference sensitivity
SD. Furthermore, the amplitude (11D level) of the electrical signal output by the sub silicon
microphone 11D indicated by the sound pressure information output by the amplitude
information acquisition unit 222 is acquired, and the 11D level and the amplitude input from the
amplitude detection unit 2262A ( The correction value is adjusted based on 11A level).
Specifically, the correction value is multiplied by 11D level / 11A level. Then, the adjusted
correction value is output to the amplifier 2261A. As a result, the amplifier 2261A performs
amplification at an amplification factor according to the adjusted correction value.
[0094]
According to this, since each amplitude correction unit 226b can adjust 11A level to 11D with
11D level as a reference, it is possible to more accurately correct the amplitude of the electric
signal output from each sub-silicon microphone 11 become able to.
18-04-2019
27
[0095]
Fifth Embodiment FIG. 15A is a diagram showing a system configuration of a silicon microphone
1e according to a fifth embodiment of the present invention.
The configuration of the silicon microphone 1e is substantially the same as the configuration of
the silicon microphone 1a, but differs in that directivity formation by the directivity forming unit
23 described later can be realized. Specifically, in the silicon microphone 1e, although the silicon
microphone chip 10 having the same configuration as that of the silicon microphone 1a is used,
as shown in FIG. The sub-silicon microphones 11 are arranged in the respective spaces.
[0096]
That is, on the substrate 31 of the housing 30b, there is provided a vertical wall 36 which divides
the inside into two so as to partition the arrangement space of the silicon microphone chip 10
and the signal processing chip 20b. , A lower wall 37 at a position corresponding to the vertical
wall 36 and a cross-shaped lower wall 38 are formed so as to divide each sub silicon microphone
of the silicon microphone chip into one room, and the silicon microphone chip 10 is formed. It is
exposed to the top of the support layer of The partition wall is constituted by the vertical wall 36
and the lower walls 37, 38. In addition, a hole 34 b for taking in an external sound is formed in
the lid 32 b for each sub silicon microphone 11. It is desirable to arrange the holes 34b as far
apart as possible from each other in order to specify the direction of arrival of sound.
[0097]
The silicon microphone chip 10 and the signal processing chip 20 b are electrically connected
via the terminals provided on the vertical wall 36 of the substrate 31. Also in this case, as
described above, the silicon microphone chip 10 may be a single chip, or may be a plurality of
silicon microphone chips 10 for each sub silicon microphone 11.
[0098]
18-04-2019
28
Further, as shown in FIG. 15B, the signal processing chip 20b further includes a directivity
forming unit 23 in the signal processing chip 20a. Hereinafter, with respect to signal processing
performed in the signal processing chip 20b, differences from the signal processing chip 20a will
be described.
[0099]
The directivity forming unit 23 acquires, from the A / D conversion unit 21, electric signals
output from each of the plurality of sub-silicon microphones 11 having different sensitivities, and
realizes formation of directivity using the electric signals. That is, the directivity forming unit 23
controls the amplitude of the synthesized signal for each direction of arrival of the sound by
synthesizing the electric signals output from the respective sub silicon microphones 11 while
shifting the phase, thereby forming directivity. .
[0100]
Here, since the sensitivities of the sub-silicon microphones 11 are different from each other as
described above, the amplitudes of the electric signals output from the respective sub-silicon
microphones 11 are different from each other even if the sound with the same sound pressure
arrives. For this reason, although it is not possible to form accurate directivity as it is, the
directivity forming unit 23 first performs processing for making the amplitudes uniform, and
then synthesizes them while shifting the phase, so that directivity can be accurately generated.
Realize to form. The directivity forming unit 23 outputs a synthesized signal obtained by the
synthesis to the outside of the silicon microphone 1 e.
[0101]
FIG. 17 is a schematic block diagram showing functional blocks of the directivity forming unit 23.
As shown in FIG. As shown in the figure, the directivity forming unit 23 includes a precombination processing unit 231, a directivity control unit 232, four delay processing units 233
(233A to 233D), and an input select / composition unit 234. .
[0102]
18-04-2019
29
The combining pre-processing unit 231 performs an amplitude correction process to make the
amplitudes of the electric signals output from the respective sub silicon microphones 11 uniform.
Specifically, the amplitude of the electrical signal output from at least a part of each sub-silicon
microphone 11 is a correction value based on the sensitivity of the sub-silicon microphone 11
outputting the electrical signal and a predetermined reference sensitivity. to correct. More
specific processing is the same as that of the pre-combination processing means (the
combination pre-processing means configured by each combination pre-processing unit 226a or
each combination pre-processing unit 226b) described in the first embodiment or the fourth
embodiment. It is good.
[0103]
Each sub-silicon microphone 11 constitutes a silicon microphone array in which a plurality of
silicon microphones are disposed at spatially different positions. The directivity forming unit 23
implements signal separation, noise removal and the like by forming directivity using this silicon
microphone array.
[0104]
Specifically, the directivity control unit 232 first determines which sub silicon microphone 11 is
used to form directivity. Further, the directivity control unit 232 identifies the direction in which
the directivity is to be formed, and based on the identified direction, delays of the electric signal
output from each of the sub-silicon microphones 11 determined to be used in forming the
directivity. Determine the amount.
[0105]
Each delay processing unit 233 delays the electric signal output from each sub-silicon
microphone 11 after the correction processing by the combination preprocessing unit 231 based
on the delay amount thus determined.
[0106]
The input select / combine unit 234 is an electrical signal output from each of the sub silicon
microphones 11 that the directivity control unit 232 decides to use when forming directivity, and
18-04-2019
30
after delay processing by each delay processing unit 233 The directivity is formed by combining
in the method according to the specific content of the directivity (beam steering that emphasizes
only the sound wave component from a specific direction or null steering that cancels the sound
wave component in a specific direction) .
[0107]
FIG. 18 is a diagram for explaining the directivity formation by the directivity formation unit 23
in more detail.
The figure shows an example in the case of forming directivity using the sub silicon microphone
11A and the sub silicon microphone 11B.
[0108]
Assuming that the distance between the center of the diaphragm 15 of the sub silicon
microphone 11A and the center of the diaphragm 15 of the sub silicon microphone 11B is d, a
sound wave (plane wave coming from the direction θ shown in FIG. 18 to the diaphragm 15 of
the sub silicon microphone 11B ) Reaches the diaphragm 15 through a distance dsin θ longer
than the same sound wave arriving at the diaphragm 15 of the sub-silicon microphone 11A.
As a result, for the same sound wave, the diaphragm 15 of the sub silicon microphone 11B
vibrates with a delay of (d sin θ) / c (c is the speed of sound) compared to the diaphragm 15 of
the sub silicon microphone 11A.
[0109]
Here, it is assumed that the directivity control unit 232 determines to form directivity in the θ
direction. Then, the directivity control unit 232 determines the delay amount of the electric
signal output from the sub silicon microphone 11A as (d sin θ) / c. When it is determined that
the directivity control unit 232 forms directivity in the θ direction, the delay processing unit
233A delays the electric signal output from the sub silicon microphone 11A so as to cancel out
the delay (d sin θ) / c. That is, the electric signal output from the sub silicon microphone 11A is
18-04-2019
31
delayed by (d sin θ) / c. As a result, the delay is canceled, and an electric signal having no time
difference is input to the input selection / combination unit 234 for the sound wave coming from
the direction θ. On the other hand, as a result of the delay processing by the delay processing
unit 233A, for the sound waves coming from directions other than the direction θ, a time
difference remains or a new time difference is added.
[0110]
The input select / combine unit 234 is configured to include an adder 2341 and a subtractor
2342. When beam steering is performed, the input select / combine unit 234 is an electrical
signal output from each of the sub silicon microphone 11A and the sub silicon microphone 11B
using the adder 2341, and after delay processing by each delay processing unit 233 Add things.
As a result, the amplitude of the component applied to the sound wave coming from the direction
θ is doubled. On the other hand, the amplitude of the component applied to the sound wave
coming from the other direction is not twice as large or rather small because of the time
difference between the electric signals output from each of the sub silicon microphone 11A and
the sub silicon microphone 11B. Become. That is, only the component applied to the sound wave
coming from the direction θ is emphasized.
[0111]
On the other hand, when performing null steering, the input select / combine unit 234 uses the
subtractor 2342 to generate an electrical signal output from the sub-silicon microphone 11A
after being subjected to delay processing by the delay processing unit 233A to sub-silicon. The
electric signal output from the microphone 11B and subjected to delay processing by the delay
processing unit 233B is subtracted. As a result, the amplitude of the component applied to the
sound wave coming from the direction θ becomes almost zero. On the other hand, the amplitude
of the component applied to the sound wave coming from the other direction does not become as
small as zero or becomes large because of the time difference between the electric signals output
from each of the sub silicon microphones 11A and 11B. . That is, only the component applied to
the sound wave coming from the direction θ is canceled.
[0112]
As described above, according to the silicon microphone 1e, since the directivity forming unit 23
uses the electric signal corrected by the pre-combination processing unit, using the plurality of
sub-silicon microphones 11 having different sensitivities, Appropriate directivity can be formed.
18-04-2019
32
[0113]
In the example shown in FIG. 15, since the sub-silicon microphones 11A and the sub-silicon
microphones 11B are arranged in the lateral direction, the directivity forming unit 23 uses the
sub-silicon microphones 11A and the sub-silicon microphones 11B. It is possible to form lateral
directivity.
Further, the directivity forming unit 23 is, for example, plural in a direction using the sub-silicon
microphone 11A and the sub-silicon microphone 11B, in another direction using the sub-silicon
microphone 11C and the sub-silicon microphone 11D, and so on. Directionality to the direction
can also be formed.
[0114]
[Sixth Embodiment] A low sensitivity silicon microphone is suitable for detection of sound with a
large sound pressure and has good sensitivity to low frequency sound, but poor sensitivity to
high frequency sound. There is a tendency to have a frequency characteristic that is becoming.
On the other hand, silicon microphones with high sensitivity are suitable for detection of sounds
with small sound pressure and have good sensitivity to high frequency sounds, but frequencies
that are less sensitive to low frequency sounds It tends to have characteristics.
[0115]
Therefore, as in the first embodiment, when the sub-silicon microphone is switched based on the
sound pressure, if a small sound pressure sound is input, the high-sensitivity sub-silicon
microphone is selected. An electric signal of a sound having a weak range and a high treble range
(a crisp sound) is output. Further, when a large sound pressure sound is input, a low sensitivity
sub-silicon microphone is selected, so that an electric signal of a sound having a strong low range
and a low high range is output. As described above, since the sensitivity of each sub-silicon
microphone is different depending on the frequency range, that is, the frequency characteristics
of each sub-silicon microphone are not flat but uneven, as a result, the sound represented by the
output electrical signal is a sound that is difficult for the listener to hear There is a problem that
it may become
18-04-2019
33
[0116]
In the sixth embodiment of the present invention, the electric signals output from the sub-silicon
microphones 11A to 11D are corrected to obtain a silicon microphone 1f having a small
frequency difference, that is, a flat frequency characteristic. FIG. 19 is a schematic block diagram
showing functional blocks of the wide DR processing unit 22 e included in the silicon
microphone 1 f according to the sixth embodiment. The silicon microphone 1 f is obtained by
replacing the wide DR processing unit 22 a with the wide DR processing unit 22 e in the silicon
microphone 1 a. The wide DR processing unit 22 e has only the wide DR processing unit 22 a
and the point that the band characteristic control units 250 A to 250 D are provided for each
output system from the sub silicon microphones 11 A to 11 D in the front stage of the combining
unit 227 a. It is different.
[0117]
The band characteristic control units 250A to 250D have the same function except that the
parameters (gains) to be set are different, and therefore, the band characteristic control unit 250
will be representatively described and described. Further, among the sub silicon microphones
11A to 11D, one that outputs an electric signal input to the band characteristic control unit 250
is referred to as a sub silicon microphone 11. The band characteristic control unit 250 is
constituted by, for example, an equalizer capable of setting gains (correction values) for a
plurality of frequency bands, and corresponds to the sub silicon microphone 11 outputting the
electric signal from the sub silicon microphone 11 The sensitivity correction for amplification is
performed by the gain for each frequency band, and the result is output to the combining unit
227a.
[0118]
The gain for each frequency band is based on the frequency characteristic of the corresponding
sub-silicon microphone 11 so that the frequency characteristic after correction becomes flat, and
the electric signal having collected the same sound is that of the sub-silicon microphones 11A to
11D. The values are preset so as to have the same amplitude between them. The gain for each
frequency band may be set by a user operation via a display and an operation button provided on
a portable terminal on which the silicon microphone 1 f is mounted.
18-04-2019
34
[0119]
The method of determining the value when the gain for each frequency band is set in advance
will be described. For example, in the band characteristic control unit 250A to which the electric
signal from the highest sensitivity sub-silicon microphone 11A is input, the gain of the sound in
the low tone range (for example, a band of 100 to 500 Hz) is set relatively high, In the band
characteristic control unit 250D to which the electric signal from the sub-silicon microphone
11D having the lowest sensitivity is input, high frequency band (for example, 1.5 to 2 kHz band
for human voice, musical instrument sound) If so, the gain of the sound of 2 to 10 kHz) is set
relatively high. Thereby, the electric signal of each of the sub silicon microphones 11A to 11D
can output a stable detection sound regardless of the frequency band.
[0120]
The respective band characteristic control units 250A to 250D are arranged such that the sounds
represented by the four electric signals input from the respective band characteristic control
units 250A to 250D to the synthesizing unit 227a are aurally flat (the same amplitude).
Determine the value of gain for each frequency band of 250D. That is, these gains are set such
that the representative value of the output of each of the band characteristic control units 250A
to 250D matches the common reference value when the reference sound is picked up. For this
representative value, for example, an average value of the amplitude of a predetermined
frequency band (for example, 500 Hz to 10 kHz) in the outputs of the band characteristic control
units 250A to 250D may be used, or a predetermined frequency (for example, 1 kHz) An
amplitude may be used.
[0121]
In the present embodiment, the band characteristic control units 250A to 250C process the
electric signals output from the combining pre-processing units 226aA to 226aC and output
them to the combining unit 227a. However, the band characteristic control units 250A to 250C
are described. The band characteristic control units 250A to 250C process the electric signals of
the sub-silicon microphones 11A to 11C output from the A / D conversion unit 21 at the
previous stage of the combination preprocessing units 226aA to 226aC, and the band
characteristic control units 250A to 250C The electrical signals output from the processing unit
18-04-2019
35
250C may be processed by the combining pre-processing units 226aA to 226aC and output to
the combining unit 227a. In addition, when the band characteristic control units 250A to 250C
perform correction for each frequency band without providing the combination preprocessing
units 226aA to 226aC, the correction corresponding to the correction by the combination
preprocessing units 226aA to 226aC is also performed collectively. You may
[0122]
As described above, according to the present embodiment, by setting the gain for each frequency
band of each band characteristic control unit 250A to 250D, the frequency characteristic of the
output of each band characteristic control unit 250A to 250D becomes flat. The frequency
characteristic of the output of the silicon microphone 1 f also becomes flat, and it is possible to
prevent the sound represented by the electric signal output from the silicon microphone 1 f from
becoming an audible sound for the listener.
[0123]
Furthermore, in the present embodiment, since the amplitudes of the output electric signals are
not greatly different between the band characteristic control units 250A to 250D, the synthesis
unit 227a performs synthesis when switching the sub-silicon microphone 11 used. The subsilicon microphones 11A to 11D to be used can be switched without giving a sense of discomfort
to the listener by suppressing a large fluctuation of the amplitude of the electric signal output
from the unit 227a.
[0124]
Seventh Embodiment In the sixth embodiment, the band characteristic control units 250A to
250D are provided at the front stage of the combining unit 227a to correct the frequency
characteristics of the sub silicon microphones 11A to 11D. In 7, in place of the band
characteristic control units 250A to 250D, the band characteristic control unit 250a is provided
at the subsequent stage of the combining unit 227d, and the band characteristic control unit
250a corrects the frequency characteristic.
[0125]
FIG. 20 is a schematic block diagram showing functional blocks of the wide DR processing unit
22f included in the silicon microphone 1g according to the seventh embodiment.
18-04-2019
36
The silicon microphone 1g is obtained by replacing the wide DR processing unit 22a with the
wide DR processing unit 22f in the silicon microphone 1a.
In addition to the function of the combining unit 227a in the first embodiment, the combining
unit 227d in the present embodiment has a band characteristic of a selection signal representing
one of the sub-silicon microphones 11A to 11D that is selected by the selecting unit 223a. It
outputs to the control part 250a.
[0126]
The band characteristic control unit 250a amplifies (corrects) the amplitude of the input electric
signal by the gain (correction value) set for each frequency band as in the band characteristic
control units 250A to 250D. The gain corresponds to the sub silicon microphones 11A to 11D
specified by the selection signal from the synthesis unit 227d.
That is, band characteristic control unit 250a stores the gain set in band characteristic control
units 250A to 250D in the sixth embodiment, and band characteristic control is performed when
sub silicon microphone 11A is designated from synthesis unit 227d. The electric signal is
amplified using the gain set in the section 250A.
[0127]
Similarly, when sub-silicon microphone 11B is specified, band-characteristic control unit 250a
amplifies using the gain set in band-characteristic control unit 250B, and when sub-silicon
microphone 11C is specified, band-characteristic control is performed. The amplification is
performed using the gain set in the section 250C, and when the sub silicon microphone 11D is
designated, the amplification is performed using the gain set in the band characteristic control
section 250D.
[0128]
Thus, also in the present embodiment, it is possible to prevent the sound represented by the
electrical signal output from the silicon microphone 1g from becoming a sound that is difficult
for the listener to hear similarly to the sixth embodiment, without giving a sense of discomfort in
hearing. Since the sub-silicon microphones 11A to 11D to be used can be switched and the
circuit configuration of the wide DR processing unit 22f is simplified, the cost can be suppressed
low compared to the configuration of the sixth embodiment.
18-04-2019
37
[0129]
Although in the first to seventh embodiments, the synthesizing units 227a to 227d are described
as outputting the electric signal of the sub silicon microphone 11 selected based on the
amplitude information (sound pressure), the sound of the collected sound is described. When the
pressure is moderate and sufficient sensitivity can be obtained in all (or two or more) sub-silicon
microphones 11, the electric signals of all (or two or more) sub-silicon microphones 11 are
averaged and the like. , May be synthesized and output.
[0130]
Further, in the sixth embodiment, as described above, when combining section 227a combines all
(or two or more) electric signals of sub-silicon microphone 11 and outputs them, band
characteristic control sections 250A to 250D respectively Alternatively, electric signals in a
frequency band in which the sensitivity of the corresponding sub-silicon microphones 11A to
11D is good may be extracted and output, and the combining unit 227a may combine and output
these signals.
For example, the band characteristic control unit 250A extracts 0 to 1 kHz, the band
characteristic control unit 250B extracts 1 to 5 kHz, the band characteristic control unit 250C
extracts 5 to 10 kHz, and the band characteristic control unit 250D Set to extract 10 to 20 kHz.
[0131]
Although the embodiments of the present invention have been described above, the present
invention is not limited to the embodiments in any way, and it goes without saying that the
present invention can be practiced in various aspects without departing from the scope of the
invention. is there.
[0132]
FIG. 1 is a diagram showing a system configuration of a silicon microphone according to an
embodiment of the present invention.
18-04-2019
38
It is an A-A 'line end view of FIG.
It is an end elevation of a silicon microphone chip concerning an embodiment of the invention.
FIG. 1 is a front view of a silicon microphone chip according to an embodiment of the present
invention. It is a figure which shows the manufacturing method of the silicon | silicone
microphone chip concerning embodiment of this invention. It is an end elevation showing a sub
silicon microphone chip concerning an embodiment of the invention. It is a figure for
demonstrating the silicon microphone concerning Embodiment 1 of this invention, and also
shows the functional block of the wide DR process part concerning Embodiment 1. FIG. It is a
figure which shows the relationship between the sound pressure and the amplitude of the
electric signal which each sub silicon | silicone microphone concerning Embodiment 1 of this
invention outputs. It is a figure which shows the specific example of the cross fade concerning
Embodiment 1 of this invention. It is a figure for demonstrating the silicon microphone
concerning Embodiment 2 of this invention, and also shows the functional block of the wide DR
process part concerning Embodiment 2. FIG. The relationship between the sound pressure and
the amplitude of the electric signal output from each of the sub-silicon microphones according to
the second embodiment of the present invention is shown, and the relationship between the
sound pressure and the amplitude of a synthesized signal synthesized by two types of
synthesizing methods is shown. FIG. FIG. 18 is a diagram for describing a silicon microphone
according to a third embodiment of the present invention, and also shows functional blocks of a
wide DR processing unit according to the third embodiment. FIG. 21 is a diagram for describing a
silicon microphone according to a fourth embodiment of the present invention, and also shows
functional blocks of a wide DR processing unit according to the fourth embodiment. It is a figure
which shows the internal structure of the amplitude correction part concerning Embodiment 4 of
this invention. It is a figure which shows the system configuration | structure of the silicon |
silicone microphone concerning Embodiment 5 of this invention. It is the B-B 'line end view of
FIG. FIG. 21 is a diagram for describing a silicon microphone according to a fifth embodiment of
the present invention, and also shows functional blocks of a directivity forming unit according to
the fifth embodiment. It is a figure for demonstrating directivity formation by the directivity
formation part concerning Embodiment 5 of this invention. FIG. 21 is a diagram for describing a
silicon microphone according to a sixth embodiment of the present invention, and also showing
functional blocks of a wide DR processing unit according to the sixth embodiment. It is a figure
for demonstrating the silicon microphone concerning Embodiment 7 of this invention, and also
shows the functional block of the wide DR process part concerning Embodiment 7. FIG.
Explanation of sign
18-04-2019
39
[0133]
1a, 1b, 1c, 1d, 1e silicon microphones, 10 silicon microphone chips, 11 sub-silicon microphones,
12 semiconductor substrates, 13 support layers, 14A, 14B, 14C, 14D cavity holes, 15
diaphragms, 16 fixed plates, 17 holes , 18 gaps, 20a, 20b signal processing chips, 21 A / D
conversion units, 22a, 22b, 22c, 22d, 22e, 22f wide DR processing units, 23 directivity forming
units, 30a, 30b housings, 31 substrates, 32a, 32b lid, 33 bonding wires, 34a, 34b holes, 36
vertical walls, 37, 38 walls, 111 semiconductor substrates, 112, 115 silicon oxide layers, 113,
116 polysilicon layers, 114, 117, 118 resist patterns, 221a, 221b synthesis control unit, 222
amplitude information acquisition unit, 223a, 223 b selection unit, 224 saturation amplitude
information storage unit, 225 crossfade coefficient generation unit, 226a, 226b combination preprocessing unit, 227a, 227b, 227c, 227d combination unit, 228 adder, 229 amplitude correction
unit, 230 crossfade unit, 231 synthesis pre-processing unit, 232 directivity control unit, 233
delay processing unit, 234 input selection / combination unit, 2261A amplifier, 2262A amplitude
detection unit, 2263A correction value determination unit, 2341 adder, 2342 subtractor, 250
250a band characteristic Control unit.
18-04-2019
40
Документ
Категория
Без категории
Просмотров
0
Размер файла
59 Кб
Теги
description, jp2008245267
1/--страниц
Пожаловаться на содержимое документа