Technical Field
[0001] The present disclosure relates to a speaker element and an array speaker.
Background Art
[0002] Patent Literature 1 discloses a piezoelectric acoustic transducer that includes a
piezoelectric ceramic, a circular metal plate, and a case. In the piezoelectric acoustic
transducer, the piezoelectric ceramic and the metal plate are caused to vibrate in
the thickness direction of the piezoelectric ceramic by expansion or contraction of
the piezoelectric ceramic.
[0003] By disposing protrusions around the metal plate, the piezoelectric acoustic transducer
enables the metal plate, during vibration, to transport less stress in a circumferential
direction around the perimeter of the metal plate. Therefore, the resonance frequency
can be shifted to a much lower side than in conventional piezoelectric acoustic transducers.
Citation List
Patent Literature
Summary of Invention
Technical Problem
[0005] In the above-described piezoelectric acoustic transducer, vibrations of the metal
plate are regulated only at the connections between the protrusions and the case.
Accordingly, as compared with cases where the entire perimeter of a metal plate is
fixed, the metal plate produces less regulated vibrations and thus more freely vibrates
in response to vibrations of the piezoelectric ceramic.
[0006] Thus, a standing wave pattern of vibration created in the metal plate (the vibrating
body) is independent of an outer shape of the piezoelectric ceramic (the piezoelectric
element) to be deformed in accordance with a voltage signal corresponding to a sound
(for example, the pattern does not become similar to an outer shape of the piezoelectric
ceramic). Therefore, the piezoelectric acoustic transducer poses a problem of outputting
disturbed sound waves.
[0007] The present disclosure has been made in view of the foregoing circumstances, and
an objective of the disclosure is to provide a speaker element and an array speaker
that can reduce disturbed sound waves to achieve higher sound quality.
Solution to Problem
[0008] To achieve the above-described objective, the invention provides a speaker element
according to claim 1. Such a speaker element according to a first aspect of the present
disclosure in particular includes:
a diaphragm with a plurality of connection pieces disposed on an outer edge of a major
surface of the diaphragm, the connection pieces protruding outward along the major
surface and being connected to another member; and
a piezoelectric element that is layered on the diaphragm and becomes deformed under
application of a voltage to cause the diaphragm to vibrate,
wherein a thickness of the connection pieces along a direction orthogonal to the major
surface is greater than a sheet thickness of the diaphragm in a region on which the
piezoelectric element is layered, and
wherein the connection pieces protrude from the major surface in a direction orthogonal
to the major surface.
[0009] In this case, an annular wall may be formed annularly along the outer edge of the
major surface of the diaphragm, the annular wall protruding from the major surface
in a direction orthogonal to the major surface and being contiguous and flush with
the connection pieces.
[0010] A projection may be disposed on the annular wall in a region being connected to each
of the connection pieces, the projection including an inner wall that faces a center
of the major surface and protrudes toward the center of the major surface.
[0011] The projection may protrude in a curved manner as seen from a direction orthogonal
to the major surface.
[0012] The projection may be in a line-symmetrical shape with respect to a virtual straight
line extending from the center of the major surface of the diaphragm and dividing
each of the connection pieces equally.
[0013] The connection pieces may be equally spaced along the outer edge of the major surface
of the diaphragm.
[0014] The connection pieces, the number of which is at least six, may be disposed along
the outer edge of the major surface of the diaphragm.
[0015] The connection pieces, the number of which is twelve, may be disposed along the outer
edge of the major surface of the diaphragm.
[0016] The diaphragm and the piezoelectric element may be circular as seen from a direction
orthogonal to the major surface.
[0017] Furthermore, the invention provides an array speaker according to claim 10. Such
an array speaker according to a second aspect of the present disclosure includes:
a plurality of the speaker elements according to the present disclosure, the speaker
elements being arranged in a two-dimensional array.
[0018] In this case, the speaker elements, the number of which is four, may be adjacent
to one another and may be arranged so as to be individually positioned at vertices
of a square.
[0019] The speaker elements, the number of which is three, may be adjacent to one another
and may be arranged so as to be individually positioned at vertices of an equilateral
triangle.
[0020] The array speaker may include an outer frame that surrounds an array of the speaker
elements and supports the speaker elements by being connected to the connection pieces
which are included in the speaker elements and which connection pieces face the outer
frame, and
the speaker elements may be connected by linking together the connection pieces that
are not connected to the outer frame.
[0021] The array speaker may include:
an outer frame that surrounds an array of the speaker elements and supports the speaker
elements by being connected to the connection pieces which are included in the speaker
elements and which connection pieces face the outer frame; and
an auxiliary member that is disposed in a gap between the speaker elements and supports
the speaker elements by being connected to the connection pieces which are included
in the speaker elements and which connection pieces face the auxiliary member.
[0022] The array speaker may further include:
an extension that extends from an inner edge of the outer frame and is connected to
the connection pieces.
[0023] The array speaker may include:
a support frame that surrounds the individual speaker elements and is connected to
the connection pieces included in the speaker elements.
Advantageous Effects of Invention
[0024] According to the present disclosure, the thickness of the connection pieces connecting
the diaphragm to another member is greater than the sheet thickness of the diaphragm
in a region on which the piezoelectric element is layered. Hence, the connection pieces
can stably support the diaphragm, and therefore, a standing wave pattern of vibration
created in the diaphragm can conform to an outer shape of the piezoelectric element,
which becomes deformed in accordance with a voltage signal corresponding to a sound.
As a result, the diaphragm can be prevented from producing unwanted vibrations, and
thus disturbed sound waves can be reduced to improve the sound quality.
Brief Description of Drawings
[0025]
FIG. 1A is a partly broken perspective view illustrating a structure of a speaker
element according to Embodiment 1 of the present disclosure;
FIG. 1B is a perspective view of the speaker element in FIG. 1A, seen from an opposite
direction;
FIG. 2 is a cross-sectional view taken from FIG. 1B to show a structure of the speaker
element;
FIG. 3 illustrates a structure of a signal system for driving the speaker element;
FIG. 4A is an explanatory drawing (part 1) illustrating deformation of the speaker
element;
FIG. 4B is an explanatory drawing (part 2) illustrating deformation of the speaker
element;
FIG. 5A is a drawing (part 1) illustrating a relationship between the number of connection
pieces formed on a diaphragm and a stress distribution;
FIG. 5B is a drawing (part 2) illustrating a relationship between the number of connection
pieces formed on a diaphragm and a stress distribution;
FIG. 5C is a drawing (part 3) illustrating a relationship between the number of connection
pieces formed on a diaphragm and a stress distribution;
FIG. 5D is a drawing (part 4) illustrating a relationship between the number of connection
pieces formed on a diaphragm and a stress distribution;
FIG. 6 is a perspective view of the speaker element with a piezoelectric element placed
on the major surface;
FIG. 7 is a perspective view of the speaker element with no annular wall disposed;
FIG. 8 is a top view of a speaker element according to Embodiment 2 of the present
disclosure;
FIG. 9 is an enlarged top view of a region around a projection;
FIG. 10 is an enlarged perspective view of a region around a projection;
FIG. 11 is a top view showing a variation of the projection;
FIG. 12 is a top view illustrating a configuration of an array speaker according to
Embodiment 3 of the present disclosure;
FIG. 13 is a top view illustrating a configuration of an array speaker according to
Embodiment 4 of the present disclosure;
FIG. 14 is a top view illustrating a configuration of an array speaker according to
Embodiment 5 of the present disclosure; and
FIG. 15 is a top view illustrating a configuration of an array speaker according to
Embodiment 6 of the present disclosure.
Description of Embodiments
[0026] A speaker element and an array speaker according to an embodiment of the present
disclosure will now be described in detail with reference to the drawings.
Embodiment 1
[0027] As illustrated in FIGS. 1A and 1B, a speaker element 1A according to the present
embodiment is formed on a substrate 2, which is a disk-shaped stack of layers each
having a uniform thickness. A disk-shaped diaphragm 3 is formed in a central area
including a center O of the substrate 2. The diaphragm 3 is formed to be concentric
with the substrate 2.
[0028] A round surface of the diaphragm 3 on the +z side is designated as a major surface
3A, while a round surface on the -z side is designated as a back surface 3B. Since
each of the layers forming the substrate 2 has a uniform thickness, the major surface
3A and the back surface 3B are parallel to each other. An outer frame 4 (a different
member), which is ring-shaped and concentric with the diaphragm 3, is disposed around
the diaphragm 3 to be spaced apart from the diaphragm 3.
[0029] The diaphragm 3 and the outer frame 4 are connected via twelve connection pieces
5. In other words, the connection pieces 5 each protrude outward along the major surface
3A (the back surface 3B) (protruding outward in a direction along the radius of the
substrate 2 from the outer edge of the major surface 3A (the back surface 3B) and
the end of each connection piece 5 connects with the outer frame 4. The connection
pieces 5 are equally spaced by 30 degrees along the outer edge of the major surface
3A and the back surface 3B of the diaphragm 3.
[0030] The outer frame 4 is fixed to a fixing member (not illustrated). The diaphragm 3
has flexibility to be able to vibrate while being supported by the outer frame 4 via
the connection pieces 5. In this way, the diaphragm 3 is supported by a plurality
of the equally spaced connection pieces 5. As a result, when compared with cases where
the diaphragm 3 is supported all along its perimeter, the diaphragm 3 is more stably
supported, the diaphragm 3 vibrates at a greater amplitude, and the resonance frequency
of the diaphragm 3 can be set to a lower value.
[0031] As illustrated in FIG. 1B, a piezoelectric element 6 is layered on a central area
of the back surface 3B of the diaphragm 3. When a voltage is applied, the piezoelectric
element 6 becomes deformed in accordance with the voltage to cause the diaphragm 3
to vibrate. Vibrations of the diaphragm 3 make a sound. In the present embodiment,
the diaphragm 3 with the disposed connection pieces 5 and the piezoelectric element
6 form the speaker element 1A. The piezoelectric element 6 is circular as seen from
a direction (the z-axis direction) orthogonal to the major surface 3A and the back
surface 3B of the diaphragm 3 and is concentric with the substrate 2 and the diaphragm
3.
[0032] In practice, the substrate 2 is made of a silicon-on-insulator (SOI) substrate. The
SOI substrate is a wafer containing an oxide film, that is, a semiconductor substrate
having a laminated structure made of a BOX layer constituting a buried oxide film
and a silicon (SOI) layer constituting a semiconductor layer on the BOX layer. The
BOX layer is formed of a silicon oxide film (SiO
2) and has a thickness of, for example, several micrometers. An SOI substrate is used
for manufacturing semiconductors made of layers each having a uniform thickness.
[0033] As illustrated in FIG. 2, the substrate 2 is formed by layering an Si support layer
10, which includes a base wafer and the BOX layer. An Si active layer 11, which is
an element wafer active layer, is layered on the Si support layer 10. The Si active
layer 11 is formed of silicon (Si) and has a thickness of, for example, 150 µm.
[0034] As seen in FIG. 1A, in the present embodiment, the diaphragm 3 is made of the Si
active layer 11, while the outer frame 4 and the connection pieces 5 are made of the
Si support layer 10 and the Si active layer 11. Hence, the connection piece 5 protrudes
in the +z direction from the major surface 3A of the diaphragm 3, and the thickness
of the connection piece 5 along the z-axis direction of the diaphragm 3 is greater
than the sheet thickness of the diagram 3 in a region on which the piezoelectric element
6 is layered. As a result, the connection pieces 5 can more stably support the diaphragm
3. In addition, the connection piece 5 is as thick as the outer frame 4 and is contiguous
and flush with the outer frame 4. As a result, local stress to be created is reduced
and the connection pieces 5 are less likely to be damaged.
[0035] In the present embodiment, an annular wall 7, which is a wall shaped like a ring,
is formed along the outer edge of the major surface 3A of the diaphragm 3. The annular
wall 7 protrudes in the +z direction from the major surface 3A of the diaphragm 3
and is contiguous and flush with the connection pieces 5. Since the annular wall 7
is contiguous with the connection pieces 5 supporting the diaphragm 3, a relative
positional relationship between connection pieces 5 varies to a minimum extent, and
the connection pieces 5 can more stably support the diaphragm 3.
[0036] The piezoelectric element 6, or specifically a first electrode layer 12, a piezoelectric
element layer 13, and a second electrode layer 14 are layered on the Si active layer
11. The first electrode layer 12 is formed of an electrically conductive member such
as platinum or gold, and has a thickness of 1 µm or less. The piezoelectric element
layer 13 is formed of a piezoelectric material to expand and contract under the application
of a voltage, and has a thickness of several micrometers. Examples of an employed
material for the piezoelectric body include lead zirconate titanate (Pb (Zr, Ti) O
3: PZT). The second electrode layer 14 is formed of an electrically conductive member
such as platinum or gold, and has a thickness of 1 µm or less.
[0037] A signal system is connected to the speaker element 1A for supplying a voltage signal
corresponding to a sound to be produced. As illustrated in FIG. 3, the signal system
includes a sound signal output device 20 and a signal modulator 21.
[0038] The sound signal output device 20 outputs a voltage signal corresponding to a sound
to be reproduced by the speaker element 1A. The frequency of the voltage signal falls
within an audible range.
[0039] The signal modulator 21 modulates a voltage signal output by the sound signal output
device 20 with a predetermined modulation frequency. Examples of an employed predetermined
modulation frequency include a frequency around 40 kHz. Examples of an employed modulation
method for the signal modulator 21 include amplitude modulation (AM).
[0040] The voltage signal modulated by the signal modulator 21 is applied to the piezoelectric
element 6 to be a voltage signal between the second electrode layer 14 and the first
electrode layer 12. This voltage signal causes the piezoelectric element 6 to vibrate
and a sound wave is generated.
[0041] For example, as shown in FIG. 4A, when a positive voltage is applied to the second
electrode layer 14 and a negative voltage is applied to the first electrode layer
12, the piezoelectric element layer 13 expands in the xy directions indicated by arrows.
However, the Si active layer 11 does not expand, with the result that the piezoelectric
element 6 is curved to project in the -z direction.
[0042] In contrast, as shown in FIG. 4B, when a negative voltage is applied to the second
electrode layer 14 and a positive voltage is applied to the first electrode layer
12, the piezoelectric element layer 13 contracts in the xy directions indicated by
arrows. However, the Si active layer 11 does not contract, with the result that the
piezoelectric element 6 is curved to project in the +z direction.
[0043] Note that, in response to an applied voltage, the piezoelectric element layer 13
may expand or contract conversely to what is described above, depending on the polarity
of piezoelectric element layer 13. If this is the case, the piezoelectric element
layer 13 is curved in the directions opposite to those indicated in FIGS. 4A and 4B.
[0044] The foregoing voltage signal oscillates between positive and negative voltages. Thus,
in response to such voltage signals, the piezoelectric element layer 13 alternates
between the states illustrated in FIGS. 4A and 4B to vibrate. Such vibration generates
a sound wave traveling in the +z direction.
[0045] The speaker element 1A according to the present embodiment provides a greater vibration
displacement of the diaphragm 3 because the diaphragm 3 is supported via the connection
pieces 5. Hence, the electromechanical coupling coefficient measured when the diaphragm
3 is caused to vibrate with a voltage applied to the piezoelectric element 6 can be
increased.
[0046] In addition, in the speaker element 1A, the thickness of the connection pieces 5
connecting the diaphragm 3 to the outer frame 4 is greater than the sheet thickness
of the diaphragm 3 in a region on which the piezoelectric element 6 is layered. Hence,
the connection pieces 5 themselves are prevented from deforming and can stably support
the diaphragm 3, and therefore, a standing wave pattern of vibration created in the
diaphragm 3 can conform to an outer shape of the piezoelectric element 6, which becomes
deformed in accordance with a voltage signal corresponding to a sound (for example,
the pattern can be similar to an outer shape of the piezoelectric element 6). As a
result, when compared with a speaker element in which the diaphragm 3 is supported
all along its perimeter (a speaker element having no opening between the diaphragm
3 and the outer frame 4), the frequency can be set to a lower band, and furthermore,
the diaphragm 3 is prevented from producing unwanted vibrations, and thus disturbed
sound waves can be reduced to improve the sound quality.
[0047] The number of the connection pieces 5 is twelve in the present embodiment. However,
the number may not always be twelve in the present disclosure. For example, the number
of the connection pieces 5 may be three to ten as shown in FIGS. 5A, 5B, 5C, and 5D;
provided that the connection pieces 5 are equally spaced along the circumference of
the diaphragm 3.
[0048] FIGS. 5A to 5D each show a stress distribution generated on the diaphragm 3. FIG.
5A shows that, when the number of the connection pieces 5 is three (spaced by 120
degrees), the stress distribution differs between radial directions. Likewise, FIG.
5B shows that, when the number of the connection pieces 5 is four (spaced by 90 degrees),
the stress distribution differs between radial directions.
[0049] By contrast, FIG. 5C shows that, when the number of the connection pieces 5 is six
(spaced by 60 degrees), the stress varies uniformly without regard to radial directions.
The same applies to FIG. 5D, which shows ten connection pieces 5 (spaced by 36 degrees).
Thus, the stress with respect to a direction along a radius of the diaphragm 3 varies
more uniformly as the number of the connection pieces 5 increases.
[0050] When the number of the connection pieces 5 is at least six, the stress with respect
to radial directions varies uniformly without regard to radial directions. Hence,
desirably at least six connection pieces 5 are disposed along the outer edge of the
major surface 3A of the diaphragm 3.
[0051] In the present embodiment, the piezoelectric element 6 is disposed on the back surface
3B, but this is not restrictive in the present disclosure. For example, the piezoelectric
element 6 may be disposed on the major surface 3A as illustrated in FIG. 6. For this
configuration, the speaker element may be manufactured by, for example, using micro-electromechanical
systems (MEMS) technology, which is a semiconductor manufacturing technology for micro-machining,
to produce the speaker element 1A except the piezoelectric element 6, namely the diaphragm
3, the outer frame 4, the connection pieces 5, and the annular wall 7, and then bonding
the piezoelectric element 6, which is made of, for example, a ceramic, onto the back
surface 3B of the diaphragm 3 that has been produced.
[0052] As shown in FIG. 7, the annular wall 7 may not necessarily be disposed. In this case,
the connection pieces 5 are still capable of stably supporting the diaphragm 3 because
the connection pieces 5 are formed to be thicker than other portions of the diaphragm
3.
Embodiment 2
[0053] The following describes Embodiment 2 of the present disclosure.
[0054] As shown in FIG. 8, a speaker element 1B according to the present embodiment is the
same as the speaker element 1A according to Embodiment 1 above except that the annular
wall 7 is different in shape from the annular wall in the foregoing embodiment. The
annular wall 7 in the speaker element 1B includes a projection 7A disposed in a region
connected to the connection piece 5.
[0055] The projection 7A is disposed such that the inner wall facing the center O of the
major surface 3A of the diaphragm 3 protrudes toward the center of the major surface
3A. Specifically, as illustrated in FIG. 9, the projection 7A protrudes in a curved
manner as seen from the z-axis direction. In other words, the length from the inner
wall of the projection 7A to the center O continuously varies.
[0056] Further specifically, the projection 7A is in a line-symmetrical shape with respect
to a virtual straight line A extending from the center O of the major surface 3A of
the diaphragm 3 and dividing the connection piece 5 equally. The projection 7A starts
protruding at a position distant from the virtual straight line A by L2 and reaches
a maximum protrusion whose length is L1 on the virtual straight line A. In other words,
the projection 7A has the shortest length from its inner wall to the center O at a
position where the length of the protrusion is represented by L1.
[0057] Assuming that there is no projection 7A, a greater stress would be caused on regions
B1 and B2 (see FIG. 10) than on other regions of the diaphragm 3, the regions B1 and
B2 corresponding to a joint between the inner wall of the annular wall 7 where the
connection piece 5 is formed and the diaphragm 3. Disposing the projection 7A on the
annular wall 7 can reduce the stress caused on the regions B1 and B2.
[0058] The shape of the projection 7A is not limited to the one illustrated in FIG. 9. For
example, as illustrated in FIG. 11, a portion of the projection 7A raised from the
inner wall as seen from the z-axis direction may be partly cut off (for example, the
raised portion may be partly straight). The projection 7A may be in any shape as long
as a stress locally caused on the diaphragm 3, such as the stress caused on the regions
B1 and B2, can be reduced.
[0059] According to the present embodiment, the projection 7A can reduce a stress locally
caused on the diaphragm 3. As a result, the diaphragm 3 can produce stable vibrations,
and a sound corresponding to a voltage signal given to the piezoelectric element 6
can be reproduced with greater fidelity. Furthermore, the diaphragm 3 is protected
from damage that may be caused by a locally created stress.
Embodiment 3
[0060] The following describes Embodiment 3 of the present disclosure.
[0061] In Embodiments 1 and 2 above, configurations of single speaker elements 1A and 1B
have been described. An array speaker 100A, which is described in the present embodiment,
includes a plurality of the speaker elements 1A arranged in a two-dimensional array
as illustrated in FIG. 12.
[0062] The array speaker 100A as a whole is disk-shaped, and an annular outer frame 4 is
disposed on the outermost circumference thereof. The outer frame 4 is fixed to a fixing
member (not illustrated). The plurality of the speaker elements 1A is arranged in
an area surrounded by an inner circumferential wall of the outer frame 4. The plurality
of the speaker elements 1A is arranged such that sounds are produced in the same +z
direction.
[0063] The speaker elements 1A are arranged such that every three speaker elements 1A adjacent
to one another are positioned at vertices of an equilateral triangle. The outer frame
4 supports the speaker elements 1A by being connected to those connection pieces 5
which are included in the speaker elements 1A and which face the outer frame 4. The
connection pieces 5 included in each speaker element 1A are used to connect adjacent
speaker elements 1A. In this way, the speaker elements 1A are structured to support
one another.
[0064] Since twelve connection pieces 5 are spaced by 30 degrees around each speaker element
1A, the connection pieces 5 are at the same positions between any adjacent speaker
elements 1A when the speaker elements 1A are positioned at vertices of an equilateral
triangle. Therefore, the speaker elements 1A can be easily connected by linking together
those connection pieces 5 which are at the same positions.
[0065] In order that the outer frame 4 is uniformly spaced apart from the speaker elements
1A, arc-shaped extensions 4A connected to the connection pieces 5 are disposed on
the inner edge of the outer frame 4. As a result, the lengths of the connection pieces
5 are kept as uniform as possible, and the supported speaker elements 1A remain well-balanced.
[0066] According to the present embodiment, the speaker elements 1A are directly connected
to each other, and thus the plurality of the speaker elements 1A to produce sounds
in the same +z direction can be closely arranged, whereby higher directivity is achieved.
[0067] The number of the arranged speaker elements 1A is six in the present embodiment,
but the number is not limited to six in the present disclosure. The number of the
speaker elements 1A may be less than six, or may be seven or more. In place of the
speaker elements 1A, the speaker elements 1B (see FIG. 8) may be arranged.
Embodiment 4
[0068] The following describes Embodiment 4 of the present disclosure.
[0069] An array speaker 100B according to the present embodiment also includes a plurality
of the speaker elements 1A arranged in a two-dimensional array as illustrated in FIG.
13. While the array speaker 100A according to Embodiment 3 above includes the speaker
elements 1A arranged such that adjacent speaker elements 1A are positioned at vertices
of an equilateral triangle, the array speaker 100B includes four speaker elements
1A, which are adjacent to one another and are arranged to be positioned at vertices
of a square.
[0070] The array speaker 100B as a whole is square-shaped, and an annular outer frame 4
is disposed on the outermost perimeter with the inner wall of the outer frame 4 including
semicircular portions each protruding toward the speaker elements 1A. The outer frame
4 is fixed to a fixing member (not illustrated). The plurality of the speaker elements
1A is arranged in an area surrounded by the inner wall of the outer frame 4.
[0071] The outer frame 4 supports the speaker elements 1A by being connected to those connection
pieces 5 which are included in the speaker elements 1A and which face the outer frame
4. A circular auxiliary member 8 is placed among the speaker elements 1A adjacent
to one another. The auxiliary member 8 supports the speaker elements 1A by being connected
to those connection pieces 5 which are included in the speaker elements 1A and which
face the auxiliary member 8. The speaker elements 1A in the array speaker 100B can
be more stably supported because the connection pieces 5 are connected not only to
the outer frame 4 fixed to a fixing member but also to the auxiliary member 8 fixed
to a fixing member. Note that the auxiliary member 8 may not necessarily be fixed
to a fixing member.
[0072] In order that the outer frame 4 is uniformly spaced from the speaker elements 1A,
extensions 4A each being connected to the connection pieces 5, being semicircular
or quadrant-like, and being an equivalent of the auxiliary member 8, are disposed
on the inner edge of the outer frame 4. As a result, the lengths of the connection
pieces 5 are kept as uniform as possible, and the supported speaker elements 1A remain
well-balanced.
[0073] Since twelve connection pieces 5 are spaced by 30 degrees around each speaker element
1A as described above, the connection pieces 5 are at the same positions between any
adjacent speaker elements 1A when the speaker elements 1A are positioned at vertices
of a square. Therefore, the speaker elements 1A can be easily connected by linking
together those connection pieces 5 which are at the same positions.
[0074] The plurality of the speaker elements 1A is arranged such that sounds are produced
in the same +z direction, which makes the array speaker 100B an array speaker having
a high directivity. Furthermore, the speaker elements 1A producing sounds in the same
direction are directly connected to each other so as to be closely arranged, whereby
higher directivity is achieved.
[0075] The number of the arranged speaker elements 1A is four in the present embodiment,
but the number is not limited to four in the present disclosure. The number of the
speaker elements 1A may be less than four, or may be five or more. In place of the
speaker elements 1A, the speaker elements 1B may be arranged.
Embodiment 5
[0076] The following describes Embodiment 5 of the present disclosure.
[0077] In the array speaker 100A according to Embodiment 3 above, the connection pieces
5 included in each speaker element 1A are used to connect adjacent speaker elements
1A, as illustrated in FIG. 14. In the array speaker 100C according to the present
embodiment, triangular auxiliary members 8 are used to connect the connection pieces
5 included in the speaker elements 1A adjacent to each other.
[0078] As with the outer frame 4, the auxiliary members 8 are fixed to a fixing member (not
illustrated). The auxiliary members 8, each of which is placed in a gap between the
speaker elements 1A, support the speaker elements 1A by being connected to those connection
pieces 5 which are included in the speaker elements 1A and which face the auxiliary
members 8. The speaker elements 1A in the array speaker 100C can be more stably supported
because the connection pieces 5 are connected not only to the outer frame 4 fixed
to a fixing member but also to the auxiliary members 8 fixed to a fixing member. Note
that the auxiliary members 8 may not necessarily be fixed to a fixing member.
[0079] In order that the outer frame 4 is uniformly spaced apart from the speaker elements
1A, arc-shaped extensions 4A connected to the connection pieces 5 are disposed on
the inner edge of the outer frame 4. As a result, the lengths of the connection pieces
5 are kept as uniform as possible, and the supported speaker elements 1A remain well-balanced.
Embodiment 6
[0080] The following describes Embodiment 6 of the present disclosure.
[0081] As illustrated in FIG. 15, the array speaker 100D according to Embodiment 6 includes
four speaker elements 1A adjacent to one another, the speaker elements 1A being arranged
to be positioned at vertices of a square. The array speaker 100D further includes
a support frame 9. The support frame 9 surrounds the individual speaker elements 1A
and is connected to the connection pieces 5 included in the speaker elements 1A.
[0082] The support frame 9 is fixed to a fixing member (not illustrated). In addition, the
support frame 9 is placed between the speaker elements 1A, and thus connected to all
the connection pieces 5 included in the speaker elements 1A to support the speaker
elements 1A. Since all the connection pieces 5 are supported by the support frame
9 included in the array speaker 100D, the speaker elements 1A can be more stably supported.
[0083] The diaphragm 3 is disk-shaped in the foregoing embodiments, but this is not restrictive
in the present disclosure. For example, the diaphragm 3 may be like an oval plate
or may be in a rectangular or any other polygonal shape.
[0084] Materials and sizes of the speaker elements 1A and 1B and the array speakers 100A
to 100D are provided as examples only and are not restrictive. The sizes may be adjusted,
as appropriate, depending on the specific apparatus on which the speaker device is
mounted.
[0085] In the foregoing embodiments, PZT is used as the piezoelectric material, but another
piezoelectric material may be used. Any other piezoelectric material, such as BaTiO
3 or PbTiO
3, or a piezoelectric single crystal, such as quartz or lithium niobate, may be used.
A piezoelectric polymer film, such as zinc oxide (ZnO), vinylidene fluoride, or trifluoroethylene
polymers, may also be used.
[0086] Amplitude modulation (AM) is used as a modulation method in the foregoing embodiments,
but frequency modulation (FM) may also be used.
[0087] The foregoing describes some example embodiments for explanatory purposes. Although
the foregoing discussion has presented specific embodiments, persons skilled in the
art will recognize that changes may be made in form and detail without departing from
the scope of the invention. Accordingly, the specification and drawings are to be
regarded in an illustrative rather than a restrictive sense. This detailed description,
therefore, is not to be taken in a limiting sense, and the scope of the invention
is defined only by the appended claims.
Industrial Applicability
[0088] The present disclosure can be applied to a speaker which is attached to any of a
variety of electrical apparatuses including portable devices such as smart phones,
and which is needed to reproduce sounds with high directivity.
Reference Signs List
[0089]
- 1A, 1B
- Speaker element
- 2
- Substrate
- 3
- Diaphragm
- 3A
- Major surface
- 3B
- Back surface
- 4
- Outer frame
- 4A
- Extension
- 5
- Connection piece
- 6
- Piezoelectric element
- 7
- Annular wall
- 7A
- Projection
- 8
- Auxiliary member
- 9
- Support frame
- 10
- Si support layer
- 11
- Si active layer
- 12
- First electrode layer
- 13
- Piezoelectric element layer
- 14
- Second electrode layer
- 20
- Sound signal output device
- 21
- Signal modulator
- 100A, 100B, 100C 100D
- Array speaker
1. A speaker element (1A) comprising:
a diaphragm (3) with a plurality of connection pieces (5) disposed on an outer edge
of a major surface (3A) of the diaphragm (3), the connection pieces (5) protruding
outward along the major surface (3A) and being connected to another member; and
a piezoelectric element (6) that is layered on the diaphragm (3) and becomes deformed
under application of a voltage to cause the diaphragm (3) to vibrate,
characterized in that
the connection pieces (5) are prevented from deforming, by having a thickness of the
connection pieces (5) along a direction orthogonal to the major surface (3A) greater
than a sheet thickness of the diaphragm (3) in a region on which the piezoelectric
element (6) is layered, and
the connection pieces (5) protrude from the major surface (3A) in a direction orthogonal
to the major surface (3A).
2. The speaker element (1A) according to claim 1,
wherein an annular wall (7) is formed annularly along the outer edge of the major
surface (3A) of the diaphragm (3), the annular wall (7) protruding from the major
surface (3A) in a direction orthogonal to the major surface (3A) and being contiguous
and flush with the connection pieces (5) along surfaces, of the respective connection
pieces (5), parallel to the major surface (3A).
3. The speaker element (1A) according to claim 2,
wherein a projection (7A) is disposed on the annular wall (7) in a region being connected
to each of the connection pieces (5), the projection (7A) comprising an inner wall
that faces a center of the major surface (3A) and protrudes toward the center of the
major surface (3A).
4. The speaker element (1A) according to claim 3,
wherein the projection (7A) protrudes in a curved manner as seen from a direction
orthogonal to the major surface (3A).
5. The speaker element (1A) according to claim 4,
wherein the projection (7A) is in a line-symmetrical shape with respect to a virtual
straight line extending from the center of the major surface (3A) of the diaphragm
(3) and dividing each of the connection pieces (5) equally.
6. The speaker element (1A) according to any one of claims 1 to 3,
wherein the connection pieces (5) are equally spaced along the outer edge of the major
surface (3A) of the diaphragm (3).
7. The speaker element (1A) according to claim 6,
wherein the connection pieces (5), the number of which is at least six, are disposed
along the outer edge of the major surface (3A) of the diaphragm (3).
8. The speaker element (1A) according to claim 7,
wherein the connection pieces (5), the number of which is twelve, are disposed along
the outer edge of the major surface (3A) of the diaphragm (3).
9. The speaker element (1A) according to any one of claims 1 to 8,
wherein the diaphragm (3) and the piezoelectric element (6) are circular as seen from
a direction orthogonal to the major surface (3A).
10. An array speaker comprising:
a plurality of the speaker elements (1A) according to any one of claims 1 to 9, the
speaker elements (1A) being arranged in a two-dimensional array.
11. The array speaker according to claim 10,
wherein the speaker elements (1A), the number of which is four, are adjacent to one
another and are arranged so as to be individually positioned at vertices of a square.
12. The array speaker according to claim 10,
wherein the speaker elements (1A), the number of which is three, are adjacent to one
another and are arranged so as to be individually positioned at vertices of an equilateral
triangle.
13. The array speaker according to any one of claims 10 to 12, comprising:
an outer frame (4) that surrounds an array of the speaker elements (1A) and supports
the speaker elements (1A) by being connected to the connection pieces (5) which are
included in the speaker elements (1A) and which connection pieces (5) face the outer
frame (4),
wherein the speaker elements (1A) are connected by linking together the connection
pieces (5) that are not connected to the outer frame (4).
14. The array speaker according to any one of claims 10 to 12, comprising:
an outer frame (4) that surrounds an array of the speaker elements (1A) and supports
the speaker elements (1A) by being connected to the connection pieces (5) which are
included in the speaker elements (1A) and which connection pieces (5) face the outer
frame (4); and
an auxiliary member (8) that is disposed in a gap between the speaker elements (1A)
and supports the speaker elements (1A) by being connected to the connection pieces
(5) which are included in the speaker elements (1A) and which connection pieces (5)
face the auxiliary member (8).
15. The array speaker according to claim 13 or 14, further comprising:
an extension (4A) that extends from the outer frame (4) and is connected to the connection
pieces (5).
16. The array speaker according to any one of claims 10 to 12, comprising:
a support frame (9) that surrounds the individual speaker elements (1A) and is connected
to the connection pieces (5) included in the speaker elements (1A).
1. Lautsprecherelement (1A) mit:
einer Membran (3) mit einer Vielzahl von Verbindungsstücken (5), die an einer Außenkante
einer Hauptfläche (3A) der Membran (3) angeordnet sind, wobei die Verbindungsstücke
(5) entlang der Hauptfläche (3A) nach außen vorstehen und mit einem anderen Bauteil
verbunden sind; und
einem piezoelektrischen Element (6), das auf die Membran (3) geschichtet ist und sich
beim Anlegen einer Spannung verformt, um die Membran (3) in Schwingung zu versetzen,
dadurch gekennzeichnet, dass
die Verbindungsstücke (5) an einer Verformung gehindert werden, indem eine Dicke der
Verbindungsstücke (5) entlang einer Richtung senkrecht zur Hauptfläche (3A) größer
als eine Bahndicke der Membran (3) ist in einem Bereich ist, auf dem das piezoelektrische
Element (6) geschichtet ist und
die Verbindungsstücke (5) von der Hauptfläche (3A) in einer Richtung senkrecht zur
Hauptfläche (3A) vorstehen.
2. Lautsprecherelement (1A) nach Anspruch 1,
wobei eine ringförmige Wand (7) ringförmig entlang der Außenkante der Hauptfläche
(3A) der Membran (3) gebildet ist, wobei die ringförmige Wand (7) von der Hauptfläche
(3A) in einer Richtung senkrecht zur Hauptfläche (3A) vorsteht und angrenzend und
bündig ist mit den Verbindungsstücken (5), entlang Oberflächen der jeweiligen Verbindungsstücke
(5), die parallel zu der Hauptfläche (3A) liegen.
3. Lautsprecherelement (1A) nach Anspruch 2,
wobei ein Vorsprung (7A) an der ringförmigen Wand (7) in einem Bereich angeordnet
ist, der mit jedem der Verbindungsstücke (5) verbunden ist, wobei der Vorsprung (7A)
eine Innenwand umfasst, die einer Mitte der Hauptfläche (3A) zugewandt ist und zur
Mitte der Hauptfläche (3A) vorragt.
4. Lautsprecherelement (1A) nach Anspruch 3,
wobei der Vorsprung (7A), gesehen aus einer Richtung senkrecht zu der Hauptfläche
(3A), in einer gekrümmten Weise hervorsteht.
5. Lautsprecherelement (1A) nach Anspruch 4,
wobei der Vorsprung (7A) eine liniensymmetrische Form in Bezug auf eine virtuelle
gerade Linie hat, die sich von der Mitte der Hauptfläche (3A) der Membran (3) erstreckt
und jedes der Verbindungsstücke (5) gleich teilt.
6. Lautsprecherelement (1A) nach einem der Ansprüche 1 bis 3,
wobei die Verbindungsstücke (5) entlang der Außenkante der Hauptfläche (3A) der Membran
(3) gleichmäßig beabstandet sind.
7. Lautsprecherelement (1A) nach Anspruch 6,
wobei die Verbindungsstücke (5), deren Anzahl mindestens sechs beträgt, entlang der
Außenkante der Hauptfläche (3A) der Membran (3) angeordnet sind.
8. Lautsprecherelement (1A) nach Anspruch 7,
wobei die Verbindungsstücke (5), deren Anzahl zwölf beträgt, entlang der Außenkante
der Hauptfläche (3A) der Membran (3) angeordnet sind.
9. Lautsprecherelement (1A) nach einem der Ansprüche 1 bis 8,
wobei die Membran (3) und das piezoelektrische Element (6) aus einer Richtung senkrecht
zur Hauptfläche (3A) gesehen kreisförmig sind.
10. Array-Lautsprecher mit:
einer Vielzahl der Lautsprecherelemente (1A) nach einem der Ansprüche 1 bis 9,
wobei die Lautsprecherelemente (1A) in einer zweidimensionalen Anordnung angeordnet
sind.
11. Array-Lautsprecher nach Anspruch 10,
wobei die Lautsprecherelemente (1A), deren Anzahl vier beträgt, nebeneinander liegen
und so angeordnet sind, dass sie einzeln an Eckpunkten eines Quadrats positioniert
sind.
12. Array-Lautsprecher nach Anspruch 10,
wobei die Lautsprecherelemente (1A), deren Anzahl drei beträgt, nebeneinander liegen
und so angeordnet sind, dass sie einzeln an Scheitelpunkten eines gleichseitigen Dreiecks
positioniert sind.
13. Array-Lautsprecher nach einem der Ansprüche 10 bis 12 mit:
einem äußeren Rahmen (4), der eine Anordnung der Lautsprecherelemente (1A) umgibt
und die Lautsprecherelemente (1A) trägt, indem er mit den Verbindungsstücken (5) verbunden
ist, die in den Lautsprecherelementen (1A) enthalten sind, wobei diese Verbindungsstücke
(5) dem äußeren Rahmen (4) zugewandt sind,
wobei die Lautsprecherelemente (1A) verbunden werden, indem die Verbindungsstücke
(5) miteinander verbunden werden, die nicht mit dem äußeren Rahmen (4) verbunden sind.
14. Array-Lautsprecher nach einem der Ansprüche 10 bis 12 mit:
einem äußeren Rahmen (4), der eine Anordnung der Lautsprecherelemente (1A) umgibt
und die Lautsprecherelemente (1A) trägt, indem er mit den Verbindungsstücken (5) verbunden
ist, die in den Lautsprecherelementen (1A) enthalten sind, wobei diese Verbindungsstücke
(5) dem äußeren Rahmen (4) zugewandt sind; und
einem Hilfselement (8), das in einer Lücke zwischen den Lautsprecherelementen (1A)
angeordnet ist und die Lautsprecherelemente (1A) trägt, indem es mit den Verbindungsstücken
(5) verbunden ist, die in den Lautsprecherelementen (1A) enthalten sind, wobei diese
Verbindungsstücke (5) dem Hilfselement (8) zugewandt sind.
15. Array-Lautsprecher nach Anspruch 13 oder 14, der ferner umfasst:
eine Verlängerung (4A), die sich vom Außenrahmen (4) erstreckt und mit den Verbindungsstücken
(5) verbunden ist.
16. Array-Lautsprecher nach einem der Ansprüche 10 bis 12 mit:
einem Tragrahmen (9), der die einzelnen Lautsprecherelemente (1A) umgibt und mit den
in den Lautsprecherelementen (1A) enthaltenen Verbindungsstücken (5) verbunden ist.
1. Élément de haut-parleur (1A), comprenant :
une membrane (3) avec une pluralité de pièces de raccordement (5) disposées sur un
bord externe d'une surface majeure (3A) de la membrane (3), les pièces de raccordement
(5) faisant saillie vers l'extérieur le long de la surface majeure (3A) et étant raccordées
à un autre organe ; et
un élément piézoélectrique (6) qui est disposé en couche sur la membrane (3) et devient
déformé sous l'application d'une tension pour amener la membrane (3) à vibrer,
caractérisé en ce que
la déformation des pièces de raccordement (5) est empêchée, du fait d'une épaisseur
des pièces de raccordement (5) suivant une direction orthogonale à la surface majeure
(3A) supérieure à une épaisseur de feuille de la membrane (3) dans une région sur
laquelle l'élément piézoélectrique (6) est disposé en couche, et
les pièces de raccordement (5) font saillie depuis la surface majeure (3A) dans une
direction orthogonale à la surface majeure (3A).
2. Élément de haut-parleur (1A) selon la revendication 1,
dans lequel une paroi annulaire (7) est formée de manière annulaire le long du bord
externe de la surface majeure (3A) de la membrane (3), la paroi annulaire (7) faisant
saillie depuis la surface majeure (3A) dans une direction orthogonale à la surface
majeure (3A) et étant continue et de niveau avec les pièces de raccordement (5) le
long de surfaces, des pièces de raccordement (5) respectives, parallèles à la surface
majeure (3A).
3. Élément de haut-parleur (1A) selon la revendication 2,
dans lequel une saillie (7A) est disposée sur la paroi annulaire (7) dans une région
qui est raccordée à chacune des pièces de raccordement (5), la saillie (7A) comprenant
une paroi interne qui est face à un centre de la surface majeure (3A) et fait saillie
vers le centre de la surface majeure (3A).
4. Élément de haut-parleur (1A) selon la revendication 3,
dans lequel la saillie (7A) fait saillie de manière courbée, vue depuis une direction
orthogonale à la surface majeure (3A).
5. Élément de haut-parleur (1A) selon la revendication 4,
dans lequel la saillie (7A) se présente sous une forme axialement symétrique vis-à-vis
d'une ligne droite virtuelle s'étendant depuis le centre de la surface majeure (3A)
de la membrane (3) et divisant chacune des pièces de raccordement (5) de manière égale.
6. Élément de haut-parleur (1A) selon l'une quelconque des revendications 1 à 3, dans
lequel les pièces de raccordement (5) sont espacées de manière égale le long du bord
externe de la surface majeure (3A) de la membrane (3).
7. Élément de haut-parleur (1A) selon la revendication 6,
dans lequel les pièces de raccordement (5), dont le nombre est d'au moins six, sont
disposées le long du bord externe de la surface majeure (3A) de la membrane (3).
8. Élément de haut-parleur (1A) selon la revendication 7,
dans lequel les pièces de raccordement (5), dont le nombre est de douze, sont disposées
le long du bord externe de la surface majeure (3A) de la membrane (3).
9. Élément de haut-parleur (1A) selon l'une quelconque des revendications 1 à 8, dans
lequel la membrane (3) et l'élément piézoélectrique (6) sont circulaires, vus depuis
une direction orthogonale à la surface majeure (3A).
10. Haut-parleur en réseau comprenant :
une pluralité d'éléments de haut-parleur (1A) selon l'une quelconque des revendications
1 à 9, les éléments de haut-parleur (1A) étant agencés en un réseau bidimensionnel.
11. Haut-parleur en réseau selon la revendication 10,
dans lequel les éléments de haut-parleur (1A), dont le nombre est de quatre, sont
adjacents les uns aux autres et sont agencés de façon à être positionnés individuellement
au niveau des sommets d'un carré.
12. Haut-parleur en réseau selon la revendication 10,
dans lequel les éléments de haut-parleur (1A), dont le nombre est de trois, sont adjacents
les uns aux autres et sont agencés de façon à être positionnés individuellement au
niveau des sommets d'un triangle équilatéral.
13. Haut-parleur en réseau selon l'une quelconque des revendications 10 à 12, comprenant
:
un cadre externe (4) qui entoure un réseau d'éléments de haut-parleur (1A) et supporte
les éléments de haut-parleur (1A) en étant raccordé aux pièces de raccordement (5)
qui sont incluses dans les éléments de haut-parleur (1A) et lesquelles pièces de raccordement
(5) sont face au cadre externe (4),
dans lequel les éléments de haut-parleur (1A) sont raccordés par liaison ensemble
des pièces de raccordement (5) qui ne sont pas raccordées au cadre externe (4).
14. Haut-parleur en réseau selon l'une quelconque des revendications 10 à 12, comprenant
:
un cadre externe (4) qui entoure un réseau d'éléments de haut-parleur (1A) et supporte
les éléments de haut-parleur (1A) en étant raccordé aux pièces de raccordement (5)
qui sont incluses dans les éléments de haut-parleur (1A) et lesquelles pièces de raccordement
(5) sont face au cadre externe (4) ; et
un organe auxiliaire (8) qui est disposé dans un écartement entre les éléments de
haut-parleur (1A) et supporte les éléments de haut-parleur (1A) en étant raccordé
aux pièces de raccordement (5) qui sont incluses dans les éléments de haut-parleur
(1A) et lesquelles pièces de raccordement (5) sont face à l'organe auxiliaire (8).
15. Haut-parleur en réseau selon la revendication 13 ou 14, comprenant en outre :
une extension (4A) qui s'étend depuis le cadre externe (4) et est raccordée aux pièces
de raccordement (5).
16. Haut-parleur en réseau selon l'une quelconque des revendications 10 à 12, comprenant
:
un cadre de support (9) qui entoure les éléments de haut-parleur (1A) individuels
et est raccordé aux pièces de raccordement (5) qui sont incluses dans les éléments
de haut-parleur (1A).