close

Вход

Забыли?

вход по аккаунту

?

JPS62200900

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 JPS62200900
[0001]
[Industrial field of application] The present invention is suitable for use, for example, for
detecting an electrical signal according to the vibration state of a diaphragm attached to a
diaphragm of a speaker, so-called motional feedback signal (hereinafter referred to as MFB
signal) Piezoelectric sensor. SUMMARY OF THE INVENTION The present invention is a
piezoelectric sensor suitable for use in detecting, for example, a so-called MFB signal attached to
a diaphragm of a speaker and corresponding to the vibration state of the diaphragm, the
substrate comprising a piezoelectric element In the piezoelectric sensor mounted on the
piezoelectric element, the piezoelectric element is configured by sticking a polymer piezoelectric
film to a plate material, thereby increasing the design freedom of the first resonance frequency,
the sensitivity, the capacitance and the first The peak level at the resonance frequency can be
lowered, and at the same time, the weight can be reduced. [Prior Art] A piezoelectric sensor
which is conventionally mounted on a diaphragm of a speaker to detect an electrical signal
according to the vibration state of the diaphragm, a so-called MFB signal, and improve the
frequency characteristics and nonlinear distortion of the speaker. As is shown in FIG. In FIG. 13,
(11 represents a substrate made of ceramic, a pedestal (2) made of ceramic is fixed to the upper
surface of this substrate (1) and copper N (3) is deposited on the upper surface of this pedestal
(2). A piezoelectric element (4) is fixed in a cantilever fashion on top of this. As this piezoelectric
element (4), a so-called bimorph formed by sandwiching a brass thin plate (5) with a ceramic
plate (61 (7) and forming a tll thin layer 81 (91 on the surface of the ceramic plate (6) A plate is
used, and the piezoelectric element (4) is fixed to the table (2) by bonding the silver thin film
layer (9) on the side in contact with the table (2) with a conductive adhesive; The silver thin film
layer (9) and the copper layer (3) are electrically connected and the silver thin film layer (8) and
the copper layer (3) on the side not in contact with the table (2) are lead wires. It electrically
connects by soldering the both ends via (11), respectively. Incidentally, (12) and (13) supply a
04-05-2019
1
predetermined DC voltage to the piezoelectric element (4), and are obtained between the brass
thin plate (5) of the piezoelectric element (4) and the silver thin film layer +81 +91. The figure
shows the leads for supplying the signal to the amplifier, one lead (12) being connected to the
brass sheet (5) and the other lead (13) being connected to the copper layer (3) of the pedestal (2)
It is done. When the piezoelectric sensor configured in this way is mounted on the diaphragm of
the speaker and a predetermined DC voltage is applied between the silver thin film layer (8) + 01
and the brass thin plate (5), the speaker diaphragm is By vibrating, the piezoelectric element (4)
vibrates (flexural vibration) corresponding to the vibration of the diaphragm at the part
projecting from the base (2), and between the silver thin film ffi (81 + 91 and the brass thin plate
(5) It is possible to obtain an electrical signal according to the vibration state of the diaphragm.
In this case, as shown in FIG. 14, such a piezoelectric sensor has a frequency characteristic
having a peak at the first resonance frequency fosH, for example, 4kllz, and vibration of the
diaphragm at a frequency lower than the first resonance frequency fast. Can detect a signal of a
voltage proportional to the acceleration of the Therefore, as shown in FIG. 15, the audio signal
input terminal (14) is supplied to the voice coil (not shown) of the speaker (16) through the
amplifier (15), and this speaker (16) is responsive to the audio signal. The piezoelectric sensor
(18) of this example is mounted on the diaphragm (17) of the speaker (16), and the output side
of the piezoelectric sensor (18) is integrated with an integrating circuit and a feedback amount
correction circuit. It is connected to the input side of the amplifier (15) via the feedback circuit
(19) to be configured, and the MFB signal of the voltage proportional to the acceleration of the
vibration of the diaphragm (17) obtained in the piezoelectric sensor (18) To the input side of the
amplifier (15), the frequency characteristics and nonlinear distortion of the speaker (16) can be
improved. In this case, the velocity feedback characteristic is a curve as shown by a solid line X in
FIG. Here, point a indicates a peak at the primary resonance frequency fosp of the speaker (16),
and if the frequency characteristics of the speaker (16) and the piezoelectric sensor (18) are flat
above this frequency fO8P, the frequency of fosp or higher Then, the velocity feedback
characteristic decreases at 6 dB / oct, but as shown in Fig. 14, the frequency characteristic of the
piezoelectric sensor (18) is the primary resonance frequency f. Since there is a peak at 5 E%, for
example 4 kHz, the peak shown by point b in FIG. Therefore, in this case, the level difference ?L
between the point a and the point b is the maximum feedback amount, and feedback of a level
higher than that causes the amplifier (15) to oscillate and the speaker (16) to be good based on
the audio signal. It becomes impossible to do reproduction. If it is possible to lower the peak level
at the first resonance frequency fO8H of the piezoelectric sensor (18) shown at point b in FIG.
16, for example, make the peak as shown by the broken line Y and lower the peak level to point
C. If it is possible, the maximum feedback amount can be made the level difference .DELTA.I
between point a and point C, and the frequency characteristic of the speaker (16) will be further
improved. [Problem to be Solved by the Invention] However, in such a conventional piezoelectric
sensor (18), a voltage proportional to the acceleration of the vibration of the diaphragm (17) of
the speaker (16) is below the first resonance frequency foBE. In order to obtain a signal, the
04-05-2019
2
primary resonance frequency fasE needs to be equal to or higher than the upper limit of the
working band of the speaker (16). For this purpose, a ceramic piezoelectric element (4) with high
hardness is used. The ceramic piezoelectric element (4) has the disadvantage that the resonance
sharpness is large and the peak level at the first resonance frequency is large.
Incidentally, in the piezoelectric sensor according to the related art (Corner 8) according to the
conventional example, as shown in FIG. 14, there is a disadvantage that the difference between
the flat portion and the peak level in the frequency characteristic is as much as 20 to 25 dB. Also,
in the conventional piezoelectric sensor (18), the ceramic resonance plate (the Young's modulus
and size of the 71 itself dominate (the degree of freedom of design is small, and the degree of
freedom of design is small). There is a disadvantage that the first resonance frequency can not be
set freely. Also, in the conventional piezoelectric sensor (18), it is necessary to further reduce the
thickness of the ceramic plate (71 (71 thickness in order to increase the sensitivity, but it is
difficult to make the current thickness smaller than There is a disadvantage that it can not be
raised above. Further, as shown in FIG. 15, the output of the piezoelectric sensor (18) is supplied
to the feedback circuit (19). In this case, the capacitance of the piezoelectric element (4) is C (F),
and the feedback circuit (19) The output frequency of the piezoelectric sensor (18) drops by 6 dB
/ oct below the frequency fL calculated by f2 = 1 / 2?CZ when the impedance of Z) is Z [?]. It is
necessary to set as below. In this case, it is necessary to determine the capacitance of the
piezoelectric element (4) in consideration of the impedance of the feedback circuit (19), but in
the conventional ceramic piezoelectric sensor (18), the degree of freedom of this design is small
There was a disadvantage. In view of such a point, the present invention enables the design
freedom of the first resonance frequency, sensitivity, and capacitance to be increased, and the
peak level at the first resonance frequency to be reduced, and further weight reduction is
achieved. It is an object of the present invention to provide a piezoelectric sensor capable of
[Means for Solving the Problems] In the piezoelectric sensor according to the present invention,
for example, as shown in FIG. 1, the piezoelectric element (20) is mounted on the substrate (21),
the piezoelectric element (20) is a plate 22) A polymer piezoelectric film (23) (24)... (30) is
adhered to the structure. [Operation] According to the present invention, the piezoelectric
element (20) is constructed by sticking the polymeric piezoelectric films (23), (24),... (30) on the
plate material (22). In this case, the Young's modulus of the polymeric piezoelectric film (23) (24)
... (30) is small, and the thickness of the polymeric piezoelectric film (23) (24) ... (30) Since it can
be made considerably thin, the peak level at the first resonance frequency for1 m, the resonance
sharpness and the first resonance frequency fosg can be determined by the plate (22), and the
design freedom at this point increases with the first The peak level at the next resonance
frequency fos + = can be lowered.
Further, since the thickness of the polymeric piezoelectric film (23) (24)... (30) can be made
considerably thin, the sensitivity can be increased and the weight can be reduced, and the
04-05-2019
3
polymeric piezoelectric film (23) (23) 24)... (30) The number of sheets and connection can be set
freely, so the capacitance and sensitivity can be set freely. An embodiment of the piezoelectric
sensor according to the present invention will be described below with reference to FIGS. 1 to 4.
In FIG. 1, (21) shows a substrate made of ceramic, a base (31) made of ceramic is fixed to the
upper surface of this substrate (21), and a piezoelectric element (20) is mounted on the upper
surface of this base (31). By bonding the lower end of the center member (22) with an adhesive,
it is fixed in a so-called cantilever shape. In this example, as shown in FIG. 2, four piezoelectric
piezoelectric films (23), (24),... (30) are respectively provided on the upper and lower surfaces of
the center member (22) of the piezoelectric element (20). Insulating adhesive (32) (32) old-(32)
is to be adhered through, in this case, both sides of the polymeric piezoelectric film (23) (24) ...
(30) In this case, silver 11 (two layers (23a) (23b) = = (30a) (30b) is formed to form an electrode.
As the center material (22), an aluminum plate, a brass plate, a steel plate, a carbon fiber
composite plate, a plastic plate, etc. can be selected according to the purpose, and the polymer
piezoelectric film (23) (24). As (3o), polyvinylidene fluoride, a copolymer of vinylidene fluoride
and ethylene trifluoride, a vinylidene cyanide polymer, a piezoelectric ceramic powder-dispersed
composite polymer film or the like can be used. Also, in this example, as shown in FIG. 3, the SN
thin film layer (23a) on the upper surface of the polymeric piezoelectric film (23)... (26) disposed
on the upper surface of the center material (22). (26a) are electrically connected so that a
positive DC voltage + V can be supplied to the silver thin film layer (23a) ... (26a) through the
terminal (33) and the upper surface of the center member (22)? ? ? (24) Silver thin film J'1
(23b) и и и (26b) on the lower surface of the polymeric piezoelectric film (23) и и и (26) and the
polymeric piezoelectric film on the lower surface of the center material (22) (27)... A polymer
piezoelectric film in which the silver thin film layer (27a) = .. (30a) on the upper surface of the
upper surface is electrically connected to each other and further disposed on the lower surface of
the center member (22) (27) и и и (30) No lower surface silver thin film layer (27b)-и и и 30b)
electrically connected to each other, the terminal (34) through a negative DC voltage - ? the
manner may provide, to as shown in the equivalent circuit of Figure 4.
In FIG. 4, the signs + and-indicate that the polymer piezoelectric film (23) иии и и и и и и supply DC
positive voltage + ? to the terminal (33), DC negative voltage-? to the terminal (34) и и и The
polarization state of (3o) is shown. When the piezoelectric sensor of this example configured in
this way is attached to, for example, the diaphragm of a speaker and a predetermined DC voltage
is supplied to the terminals (33) and (34), the vibration of the diaphragm of the speaker is
generated. The polymer piezoelectric film (23) (24) ... (3o) performs bending vibration together
with the core material (22), and the polarization in the polymer piezoelectric film (23) (24) ... (30)
The state changes, and an electric signal according to the vibration state of the diaphragm of the
speaker, so-called MFB signal, can be obtained, and this MFB signal is converted to a constant
speed form as shown in FIG. The feedback can improve the frequency characteristics of the
speaker. Here, in the piezoelectric sensor of this example, the Young's modulus of the polymeric
piezoelectric film (23) (24)... (30) is small, and the polymeric piezoelectric film (23) (24). Since
04-05-2019
4
the thickness of 30) can be made considerably thinner than that of the ceramic plate (61 (7)
shown in FIG. 13 example, for example, 1 .mu.m or less, the first resonance frequency is
determined by the Young's modulus and thickness of the ceramic plate itself. Unlike ceramicbased piezoelectric sensors in which fosE and resonance sharpness are determined, the first
resonance frequency fo + glB and resonance sharpness can be determined by the center material,
and in this respect, the design freedom can be increased. In this case, the first resonance
frequency foBH is higher than that of the ceramic piezoelectric sensor, and the resonance acuity
is suppressed to a low level. Because the feedback level can be lowered, the feedback amount can
be increased in the MFB speaker in which the piezoelectric sensor of this example is attached to
the diaphragm compared to the MFB speaker in which the ceramic piezoelectric sensor is
attached, and the frequency characteristics etc. are further improved. Have the benefit of being
able to improve. Further, in the piezoelectric sensor of the present embodiment, as described
above, since the polymer piezoelectric film (23) (24)... (30) can be made as thin as possible, it is
lighter than ceramic piezoelectric sensors. It has the benefit of being able to increase sensitivity
as well as Further, in the piezoelectric sensor of this embodiment, the connection of the
polymeric piezoelectric film (23) (24) is not limited to the case shown in FIG. 4 but the polymeric
piezoelectric film (23) as shown in FIG. ) (24) connects all of ... (30) in parallel, or that the two at
a time in parallel as shown in Figure 6 connected in series, or all series as shown in FIG. 7 In
addition, it is possible to take various connection structures such as connecting to, and to adjust
the number of polymer piezoelectric films (23) (24). There is a benefit that it can be set up
separately.
In the above embodiment, the case where the piezoelectric polymer films (23), (24),... (30) are
attached to both sides of the center member (22) has been described, but instead, It is also
possible to stick the polymeric piezoelectric film only on one side of the core material (22), and in
this case it is of course possible to obtain the same effects as described above. In the above
embodiment, the case where the piezoelectric polymer films (23), (24),... (30) are attached to
both sides of the center member (22) fixed in a cantilever shape is described. However, instead of
this, for example, as shown in FIG. 8, when both ends of the center member (22) are fixed to the
substrate (36) through the rubber members (35) and (35), as shown in FIG. When both ends of
the center material (22) are directly fixed to the substrate (36) in the same manner as shown in
FIG. 10, the center material (37) formed in a disk shape is rubber member ( When fixed to the
substrate (39) in 38), the center material (37) formed in a disk shape was fixed directly to the
substrate (39) over the entire circumference as shown in FIG. Or, as shown in FIG. 12, to form the
center piece (40) integrally with the substrate (41) Also in this case, the polymer piezoelectric
film (42)... (42) can be stuck on both sides or one side of the core materials (22) (37) (40), and in
this case as well as above. Of course, it is possible to obtain the effects. Also, the output voltage
can be increased by making the polymeric piezoelectric film into a bimorph configuration.
Although the present invention has been described as being applied to a speaker in the abovedescribed embodiment, the present invention is of course not limited to the above-described
04-05-2019
5
embodiment and can be used in various devices. Furthermore, the present invention is not
limited to the above-described embodiment, and it goes without saying that various other
configurations can be taken without departing from the scope of the present invention. [Effects
of the Invention] According to the present invention, since the peak level at & 1 at the first
resonance frequency and the first resonance frequency can be determined by the plate, design
freedom in this respect is increased. In this case, the peak level at the primary resonance
frequency can be lowered, so that in the speaker equipped with the piezoelectric sensor of the
present invention, the amount of feedback is increased more than the speaker equipped with the
ceramic based piezoelectric sensor. There is the advantage that it is possible to obtain an even
better frequency characteristic. Further, according to the present invention, since the polymeric
piezoelectric film can be made quite thin, there is a merit that the sensitivity can be increased
and the weight can be reduced, and the number of the polymeric piezoelectric films, connection
can be realized. Can be set freely, so that there is an advantage that capacitance and sensitivity
can be freely set.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a front view showing a first embodiment of the piezoelectric sensor of the present
invention, FIG. 2 is a partially enlarged front view showing the first embodiment of the present
invention, and FIG. 3 is a first embodiment of the present invention A diagram showing an
example of connection of silver electrodes formed on both sides of a polymer piezoelectric film in
FIG. 4, FIG. 4 is a diagram showing an equivalent circuit of FIG. 3 example, FIG. 5, FIG. 6 and FIG.
FIG. 8 is a perspective view showing the second embodiment of the present invention, and FIG. 9
is a perspective view showing the third embodiment of the present invention. 11 is a partially
cutaway perspective view showing a fourth embodiment of the present invention, FIG. 11 is a
partially cutaway perspective view showing a fifth embodiment of the present invention, and FIG.
12 is a sixth embodiment of the present invention FIG. 13 is a front view showing an example of
a conventional piezoelectric sensor, FIG. 14 is a diagram showing frequency characteristics of the
conventional piezoelectric sensor, and FIG. Diagram for, FIG. 16 is a graph showing the speed
feedback characteristic of Figure 15 example.
(20) is a piezoelectric element, (21) (36) (39) and (41) are each a substrate, (22) (37) and (4o)
are each a center material, (23) (24). 3o) and (42) are respectively polymeric piezoelectric films,
(23a) (23b)... (30a) and (30b) are respectively silver thin film layers.
04-05-2019
6
04-05-2019
7
Документ
Категория
Без категории
Просмотров
0
Размер файла
18 Кб
Теги
jps62200900
1/--страниц
Пожаловаться на содержимое документа