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JP2017073796

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DESCRIPTION JP2017073796
Abstract: To provide a sound generator that can be reduced in size and weight and can generate
a good sound. An excitation unit capable of taking a housing 20, a piezoelectric vibrating unit 60
having a piezoelectric element 61 disposed in the housing 20, and a noncontacting condition not
in contact with the piezoelectric vibrating unit 60 and a contacting condition 91 and a weight for
applying a load to the excitation unit 91 via the piezoelectric vibration unit 60, and in a contact
state, in a state where the load from the weight is applied to the excitation unit 91, piezoelectric
according to the sound signal The vibrating portion 60 is deformed, and the deformation of the
piezoelectric vibrating portion 60 causes the contact surface 150 with which the vibrating
portion 91 contacts to be vibrated to generate a sound from the contact surface 150. [Selected
figure] Figure 11
Sound generator
[0001]
The present invention relates to a sound generator that vibrates a contact surface with which a
sound generator contacts and generates sound from the contact surface.
[0002]
Conventional electronic devices, such as mobile phones, generate sound from speakers provided
in the electronic devices.
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1
Loudspeakers used in conventional electronic devices are mainly dynamic speakers. For example,
Patent Document 1 discloses vibration generation having a dynamic speaker structure including
a magnet, a voice coil, a diaphragm, and a case for housing these. The device is described.
[0003]
Japanese Utility Model Publication 5-85192
[0004]
However, since the vibration generating device described in Patent Document 1 has a dynamic
speaker structure, an increase in the number of parts can not be avoided and the weight becomes
heavy.
Also, the output of the dynamic speaker depends on the size of the diaphragm for generating
sound internally, and the smaller the speaker, the smaller the output. Therefore, in order to
obtain good sound characteristics, upsizing of the device can not be avoided.
[0005]
An object of the present invention made in view of such a point of view is to provide a sound
generator which can be reduced in size and weight and which can generate a good sound.
[0006]
An image display apparatus according to the present invention for achieving the above object
comprises a housing, a piezoelectric vibration portion having a piezoelectric element disposed in
the housing, and a contact state in contact with a non-contact state not contacting the
piezoelectric vibration portion. And a weight for applying a load to the vibrating portion via the
piezoelectric vibrating portion, and in the contact state, a load from the weight is applied to the
vibrating portion. The piezoelectric vibrating portion is deformed in response to the sound signal,
and the deformation of the piezoelectric vibrating portion vibrates the contact surface with which
the vibrating portion contacts to generate a sound from the contact surface.
[0007]
The cover has the vibration part, and the cover includes a cover part which is displaceable in the
housing, and the cover part brings the vibration part into the contact state at the first position
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and the vibration part at the second position. The piezoelectric vibrator may be protected as well
as in the non-contact state.
[0008]
The piezoelectric element may be driven in a state in which the cover portion is in the first
position and not driven in a state in which the cover portion is in the second position.
[0009]
The piezoelectric element may be a laminated piezoelectric element, and may be deformed in an
extending and contracting direction along the laminating direction.
[0010]
The piezoelectric vibration unit may include a covering member that transmits the vibration
caused by the deformation of the piezoelectric element to the vibration unit to vibrate the
vibration unit.
[0011]
The vibration excitation unit may include a covering member that transmits the vibration caused
by the piezoelectric vibration unit to the contact surface to vibrate the contact surface.
[0012]
According to the present invention configured as described above, it is possible to provide a
sound generator that can be reduced in size and weight and can generate a good sound.
[0013]
It is an appearance perspective view showing a schematic structure of a sound generator
concerning a 1 embodiment of the present invention.
It is an external appearance perspective view of the principal part which disassembles and shows
the back surface side of the mobile telephone of FIG.
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It is a figure which shows the structure of the lamination type piezoelectric element of FIG.
It is a figure which shows the modification of a lamination type piezoelectric element.
It is the elements on larger scale sectional drawing of the contact state of the piezoelectric
vibration part of FIG. 2, and a vibration excitation part.
It is a schematic diagram which shows the 1st position and 2nd position of the cover part of FIG.
It is a functional block diagram of the principal part of the mobile telephone of FIG.
It is a functional block diagram which shows the structure of an example of the piezoelectric
element drive part of FIG.
It is a figure which shows an example of the frequency characteristic of LPF of FIG. It is a figure
which shows arrangement | positioning of the excitation part in the sound generator of FIG. 1, a
projection part, and an elastic member. It is the schematic for demonstrating the operation |
movement as a sound generator by the mobile telephone of FIG. It is a figure which shows three
modifications of the holding | maintenance form of a piezoelectric vibration part. It is an external
appearance perspective view which shows schematic structure of a sound generator provided
with a circular shaped cover part. It is a schematic diagram which shows the 1st position and 2nd
position of the cover part of FIG. It is a figure which shows schematic structure of the principal
part which shows the modification of a cover part.
[0014]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
[0015]
FIG. 1 is an external perspective view of a sound generator according to an embodiment of the
present invention.
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The sound generator according to the present embodiment includes a mobile phone 10 such as a
smartphone, an elastic member 70, and a cover 90. The mobile phone 10 includes a housing 20
whose outer shape is substantially rectangular. In the case 20, a panel 30 and an input unit 40
are disposed on the front side of the mobile phone 10. As shown in FIG. 1, a portion of the panel
30 is cut away in the lower side of the panel 30. Is held. In addition, a battery pack, a camera
unit, and the like are mounted on the back surface side of the housing 20 and covered with the
battery lid 21.
[0016]
The panel 30 is formed of a touch panel that detects a touch, a cover panel that protects the
display unit 50, or the like, and is formed of, for example, glass or a synthetic resin such as
acrylic. The panel 30 is, for example, rectangular. The panel 30 may be a flat plate, or may be a
curved panel having a smooth surface. When the panel 30 is a touch panel, the panel 30 detects
a touch of a user's finger, a pen, a stylus pen, or the like. As a detection method of the touch
panel, any method such as a capacitance method, a resistance film method, a surface acoustic
wave method (or an ultrasonic method), an infrared method, an electromagnetic induction
method, and a load detection method can be used. In the present embodiment, for convenience of
description, the panel 30 is a touch panel.
[0017]
The input unit 40 receives an operation input from the user, and includes, for example, operation
buttons (operation keys). The panel 30 can also receive an operation input from the user by
detecting a touch from the user on a soft key or the like displayed on the display unit 50.
[0018]
The display unit 50 is a display device such as a liquid crystal display, an organic EL display, or
an inorganic EL display.
[0019]
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In the sound generator according to the present embodiment, a sheet-like elastic member 70 and
a piezoelectric vibration unit 60 inside the case 20 are provided on the side 20a of one long side
of the case 20 of the mobile phone 10 (see FIG. 2). A cover 90 for protecting the
The elastic member 70 is made of, for example, rubber, silicone, polyurethane or the like. The
cover 90 has a vibrating portion 91 and a protrusion 92. The cover 90 is provided on the
housing 20 so as to be displaceable. The user of the mobile phone 10 can move the cover 90 by
operating the projection 92 with a finger to displace it so as to slide longitudinally on the side
surface 20 a as indicated by the arrow 910. When the mobile phone 10 is placed on a horizontal
contact surface such as a desk with the side surface 20a facing downward, that is, when the
mobile phone 10 is erected sideways, the elastic member 70 and the excitation unit 91 make
contact. Supported at two points on the surface. The arrangement of the elastic member 70 and
the excitation unit 91 will be described later.
[0020]
FIG. 2 is a schematic perspective view of an essential part showing the back side of the mobile
phone 10 of FIG. 1 in an exploded manner. On the back side of the housing 20, a battery pack
80, a camera unit 81, and the like are mounted. Further, in the housing 20, a piezoelectric
vibrating portion 60 having a piezoelectric element 61 is disposed. The cellular phone 10 has, on
the rear surface side of the housing 20, a recess 200 which is a space for displacing the
excitation unit 91. The recess 200 has a surface 20 b parallel to the side surface 20 a. In
addition, the mobile phone 10 includes a holding unit 100 for housing and holding the
piezoelectric vibration unit 60 on the back side of the housing 20. The holding portion 100
extends along the short direction of the housing 20, and has a slit 101 having a uniform width
opening on the surface 20b side. In addition, the cellular phone 10 includes, on the back surface
side of the housing 20, a holding unit 900 and a holding unit 901 that store and hold both ends
of the cover unit 90. In FIG. 2, a part of the cover 90 is in a state of being accommodated and
held in the holding unit 901.
[0021]
As described later with reference to FIG. 6, when the cover 90 is displaced, the excitation unit 91
can be in a contact state in contact with the piezoelectric vibration unit 60 and in a non-contact
state not in contact with the piezoelectric vibration unit 60. In the contact state, when the cellular
phone 10 is placed on a horizontal contact surface such as a desk with the side surface 20 a
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facing downward, a weight (sound generation) that applies a load to the vibration excitation unit
91 via the piezoelectric vibration unit 60 Act as the weight of the
[0022]
The piezoelectric vibrating unit 60 includes a piezoelectric element 61, an O-ring 62, and a
covering member 63 that protects the piezoelectric element 61. The piezoelectric element is an
element that expands and contracts or bends according to the electromechanical coupling
coefficient of the constituent material by applying an electric signal (voltage). As these elements,
for example, those made of ceramic or quartz are used. The piezoelectric element may be a
unimorph, bimorph or laminated piezoelectric element. In the laminated piezoelectric element, a
laminated bimorph element in which bimorphs are laminated (for example, laminated about 8 to
40 layers), a plurality of dielectric layers made of, for example, PZT (lead zirconate titanate), and
the plurality of dielectrics There is a stack type that is formed of a laminated structure with an
electrode layer disposed between body layers. The unimorph expands and contracts when an
electrical signal is applied, the bimorph bends when an electrical signal is applied, and the stack
type stacked piezoelectric element expands and contracts along the stacking direction when an
electrical signal is applied.
[0023]
In the present embodiment, the piezoelectric element 61 is a stack-type laminated piezoelectric
element. For example, as shown in the enlarged sectional views and plan views of FIGS. 3A and
3B, the laminated piezoelectric element 61 includes, for example, a dielectric 61a made of
ceramic such as PZT and an internal electrode having a comb-like cross section. And 61b are
alternately stacked. The internal electrode 61b is alternately stacked with one connected to the
first side electrode 61c and one connected to the second side electrode 61d, so that the first side
electrode 61c or the second side electrode 61d is electrically connected. Connected to
[0024]
The laminated piezoelectric element 61 shown in FIGS. 3A and 3B has a first lead connecting
portion 61e electrically connected to the first side electrode 61c and a second side electrode 61d
at one end face. An electrically connected second lead connecting portion 61 f is formed. A first
lead wire 61g and a second lead wire 61h are connected to the first lead connection portion 61e
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and the second lead connection portion 61f, respectively. In addition, the first side surface
electrode 61c, the second side surface electrode 61d, the first lead connection portion 61e, and
the second lead connection portion 61f are connected to the first lead connection portion 61e
and the second lead connection portion 61f, respectively. In the state where 61g and the 2nd
lead wire 61h are connected, it is covered with insulating layer 61i.
[0025]
The lamination-type piezoelectric element 61 has a length in the lamination direction of, for
example, 5 mm to 120 mm. The cross-sectional shape in the direction orthogonal to the stacking
direction of the stacked piezoelectric element 61 can be, for example, a substantially square
shape of 2 mm square to 10 mm square, or any shape other than the square shape. Note that the
number of stacked layers and the cross-sectional area of the stacked piezoelectric element 61
depend on the weight of the mobile phone 10 serving as a weight (for example, 80 g to 800 g in
the case of a mobile electronic device) It is appropriately determined so that the sound pressure
or sound quality of the sound generated from the contact surface can be sufficiently secured.
[0026]
A sound signal (reproduction sound signal) is supplied to the laminated piezoelectric element 61
from the control unit 130 via the piezoelectric element drive unit 120, as described later with
reference to FIG. In other words, a voltage corresponding to the sound signal is applied to the
laminated piezoelectric element 61 from the control unit 130 via the piezoelectric element drive
unit 120. When the voltage applied from the control unit 130 is an alternating voltage, when a
positive voltage is applied to the first side electrode 61c, a negative voltage is applied to the
second side electrode 61d. Conversely, when a negative voltage is applied to the first side
electrode 61c, a positive voltage is applied to the second side electrode 61d. When a voltage is
applied to the first side electrode 61c and the second side electrode 61d, polarization occurs in
the dielectric 61a, and the laminated piezoelectric element 61 expands and contracts from the
state where no voltage is applied. The expansion and contraction direction of the laminated
piezoelectric element 61 is substantially along the lamination direction of the dielectric 61a and
the internal electrode 61b. Alternatively, the expansion / contraction direction of the laminated
piezoelectric element 61 substantially coincides with the lamination direction of the dielectric 61
a and the internal electrode 61 b. Since the multilayer piezoelectric element 61 expands and
contracts substantially along the stacking direction, there is an advantage that vibration
transmission efficiency in the expansion and contraction direction is good.
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[0027]
In FIGS. 3A and 3B, the first side surface electrode 61c and the second side surface electrode 61d
are alternately connected to the internal electrode 61b and connected to the first lead connection
portion 61e and the second lead connection portion 61f, respectively. It can also be a through
hole. In FIGS. 3A and 3B, the first lead connection portion 61e and the second lead connection
portion 61f are, as shown in FIG. You may form in 2nd side electrode 61d.
[0028]
As shown in the partially enlarged cross-sectional view of FIG. 5, the laminated piezoelectric
element 61 has one end side surface including the first lead connection portion 61 e and the
second lead connection portion 61 f in the slit 101 of the holding portion 100 of the housing 20.
It is fixed via an adhesive 102 (for example, an epoxy resin). Further, the covering member 63 is
inserted into the other end of the laminated piezoelectric element 61 and fixed by the adhesive
102.
[0029]
The covering member 63 is formed of a material that can reliably transmit the stretching
vibration by the laminated piezoelectric element 61 to the vibrating portion 91, for example, a
hard plastic. The covering member 63 is provided with an entering portion 63 a positioned in the
slit 101 and a protruding portion 63 b protruding from the housing 20 in a state where the
covering member 63 is attached to the laminated piezoelectric element 61. An O-ring 62 is
disposed on the outer periphery of the entry portion 63a. The O-ring 62 is formed of, for
example, silicone rubber. The O-ring 62 is used for movably holding the laminated piezoelectric
element 61 and at the same time makes it difficult for moisture or dust to enter the inside of the
slit 101. Moreover, the tip end of the protrusion 63 b is formed in a planar shape. The tip of the
projecting portion 63b is not limited to a flat shape, and may have any shape as long as it can
transmit the expansion / contraction vibration of the laminated piezoelectric element 61 reliably
in point contact or surface contact with the excitation portion 91. can do. In addition, in FIG. 5,
the gap between the O-ring 62 and the bonding portion of the laminated piezoelectric element
61 to the slit 101 may be filled with gel or the like to further enhance the dustproof / waterproof
effect. The piezoelectric vibrating portion 60 is mounted on the holding portion 100, and the
protruding portion 63b of the covering member 63 protrudes from the surface 20b. Further, the
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tip end of the projecting portion 63b of the covering member 63 is separated from the surface
20b by the length d in a state in which a voltage is not applied to the laminated piezoelectric
element 61 and the laminated piezoelectric element 61 does not expand or contract.
[0030]
The vibrating portion 91 is formed of a material that can reliably transmit the stretching
vibration of the laminated piezoelectric element 61 to the contact surface of a desk or the like,
such as metal, ceramic, hard plastic or the like. The vibrating portion 91 is held from both ends
by the cover portion 90 having flexibility so as not to inhibit the transmission of the vibration of
the laminated piezoelectric element 61. The excitation unit 91 has a cap 94, which is a covering
member, on the side surface 20 a side of the housing 20. The cap 94 is fixed by the adhesive
102. The cap 94 is formed of a material capable of reliably transmitting the expansion and
contraction vibration of the laminated piezoelectric element 61 transmitted through the
excitation unit 91 to the contact surface such as a desk, such as hard plastic. When it is desired
to suppress damage on the contact surface, the cap 94 may be a relatively soft plastic instead of
a hard plastic. It is not necessary for the cover 90 to have flexibility as long as the cover 90 has a
structure that does not inhibit the transmission of the vibration of the laminated piezoelectric
element 61 to the excitation unit 91, and the same material as the excitation unit 91 is used.
Good. At that time, the cover portion 90 and the excitation portion 91 may be integrally formed.
[0031]
FIG. 6A shows the contact state between the piezoelectric vibration unit 60 and the excitation
unit 91. At this time, the cover unit 90 is in the first position. Further, FIG. 6B shows a noncontact state of the piezoelectric vibration unit 60 and the excitation unit 91, and at this time, the
cover unit 90 is in the second position. The user of the mobile phone 10 operates the projection
92 to displace the cover 90 (excitation unit 91), and switches between the first position and the
second position, thereby causing the piezoelectric vibration unit 60 and the vibration unit 60 to
move. The contact state with the vibration part 91 and the non-contact state can be switched.
The first position of FIG. 6A is used when the mobile phone 10 generates a sound. That is, since
the piezoelectric vibration unit 60 and the excitation unit 91 are in contact with each other, the
vibration of the piezoelectric element is transmitted to the contact surface such as a desk via the
excitation unit 91. On the other hand, the second position in FIG. 6B is used when the mobile
phone 10 does not generate a sound. In this case, since the piezoelectric vibration unit 60 and
the excitation unit 91 are not in contact with each other, the vibration of the piezoelectric
element is not transmitted to the contact surface. Furthermore, in the non-contact state, the
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piezoelectric vibrating portion 60 is protected by the cover portion 90. Therefore, for example,
even if the cellular phone 10 falls and an impact is given to the side surface 20a from the drop
location, the cover portion 90 receives an impact, so the piezoelectric vibrating portion 60 can be
protected from the impact when it is dropped.
[0032]
Furthermore, the cover 90 functions as a switch for inputting a sound signal to the piezoelectric
element 61. As shown in FIGS. 6A and 6B, the cover unit 90 includes a switch unit 93 at an end
on the holding unit 901 side. The switch unit 93 has, for example, a conductive metal, and the
holding unit 901 has two terminals which are part of a circuit for inputting a sound signal to the
piezoelectric element 61 at the end surface 901 a. Then, at the first position of the cover portion
90, as shown in FIG. 6A, the switch portion 93 is in contact with the end surface 901a, and the
two terminals provided on the end surface 901a are through the conductive metal of the switch
portion 93. Connected. Then, the circuit for inputting a sound signal to the piezoelectric element
61 conducts, and as a result, the signal is input to the piezoelectric element 61, the piezoelectric
vibration unit 60 is driven, and the vibration is transmitted to the contact surface via the
vibration unit 91. Ru. Thus, the mobile phone 10 generates a sound from the touch surface. On
the other hand, when the cover portion 90 is displaced to the second position and the
piezoelectric vibrating portion 60 and the vibrating portion 91 are not in contact with each other,
this circuit does not conduct, so no sound signal is input to the piezoelectric element 61. The
vibrating unit 60 is not driven. Therefore, the mobile phone 10 does not generate sound.
[0033]
FIG. 7 is a functional block diagram of the main part of mobile phone 10 according to the present
embodiment. The mobile phone 10 includes a wireless communication unit 110, a piezoelectric
element drive unit 120, and a control unit 130, in addition to the panel 30, the input unit 40, the
display unit 50, and the laminated piezoelectric element 61 described above. The panel 30, the
input unit 40, the display unit 50, and the wireless communication unit 110 are connected to the
control unit 130. The laminated piezoelectric element 61 is connected to the control unit 130 via
the piezoelectric element drive unit 120.
[0034]
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The wireless communication unit 110 has a known configuration, and is wirelessly connected to
a communication network via a base station or the like. The control unit 130 is a processor that
controls the overall operation of the mobile phone 10. The control unit 130 applies a
reproduction sound signal (a voice according to the other party of the call or a voltage according
to a reproduction sound signal of a ring tone or a melody including music) to the laminated
piezoelectric element 61 via the piezoelectric element drive unit 120. Note that the reproduction
sound signal may be based on music data stored in the internal memory, or music data stored in
an external server or the like may be reproduced via a network.
[0035]
The piezoelectric element drive unit 120 includes, for example, a signal processing circuit 121, a
booster circuit 122, and a low pass filter (LPF) 123, as shown in FIG. The signal processing
circuit 121 is constituted by, for example, a digital signal processor (DSP) having an equalizer, an
A / D conversion circuit, etc., and the digital signal from the control circuit 130 is required to
have equalizing processing, D / A conversion processing, etc. Signal processing to generate an
analog reproduction sound signal and output it to the booster circuit 122. The function of the
signal processing circuit 121 may be incorporated in the control circuit 130.
[0036]
The booster circuit 122 boosts the voltage of the input analog reproduction sound signal and
applies the voltage to the laminated piezoelectric element 61 via the LPF 123. Here, the
maximum voltage of the reproduction sound signal applied to the laminated piezoelectric
element 61 by the booster circuit 122 can be, for example, 10 Vpp to 50 Vpp, but is not limited
to such a range. It can be appropriately adjusted according to the performance of the element 61.
A direct current voltage may be biased to the reproduction sound signal applied to the laminated
piezoelectric element 61, and a maximum voltage may be set around the bias voltage.
[0037]
Further, the power loss is generally larger at higher frequencies as the piezoelectric element 61
is not limited to the laminated piezoelectric element 61. Therefore, the LPF 123 has a frequency
characteristic that attenuates or cuts at least a part of frequency components of about 10 kHz to
50 kHz or more Alternatively, it is set to have a frequency characteristic in which the attenuation
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factor is gradually increased. FIG. 9 shows, as an example, the frequency characteristic of the LPF
123 when the cutoff frequency is about 20 kHz. Thus, power consumption can be suppressed by
attenuating or cutting high frequency components.
[0038]
Next, with reference to FIG. 10, the arrangement of the excitation unit 91, the protrusion 92, and
the elastic member 70 will be described. FIG. 10 shows that the mobile phone 10 is placed on the
horizontal contact surface 150 such as a desk with the side surface 20 a facing downward when
the cover 90 is in the first position. Here, a desk is an example of the to-be-contacted member of
this invention, and the contact surface 150 is an example of the contact surface which a sound
generator contacts. As shown in FIG. 10, the mobile phone 10 is supported at two points on the
contact surface 150 by the excitation unit 91 and the elastic member 70. Point G is the center of
gravity of the mobile phone 10. That is, point G is the center of gravity of the weight of the sound
generator.
[0039]
In FIG. 10, the elastic member 70 has a lowermost end 701. The lowermost end portion 701 is a
portion of the elastic member 70 that abuts on the contact surface 150 when the cellular phone
10 is placed on the horizontal contact surface 150 such as a desk with the side surface 20 a
facing downward.
[0040]
The excitation unit 91 has a lowermost end 911. The lowermost end portion 911 is a portion of
the vibrating portion 91 that abuts on the contact surface 150 when the cellular phone 10 is
placed on the horizontal contact surface 150 such as a desk with the side surface 20 a
downward. The lowest end 911 is, for example, the tip of the cap 94.
[0041]
The mobile phone 10 has a lowermost end 201. In the lowermost end portion 201, it is assumed
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that the vibrating portion 91 does not exist when the mobile phone 10 is placed on the
horizontal contact surface 150 such as a desk with the side surface 20a facing downward in the
mobile phone 10. In this case, it is a place that abuts on the contact surface 150. The lowermost
end 201 of the mobile phone 10 is, for example, a corner of the housing 20, but is not limited
thereto. When the side surface 20 a is provided with a protrusion that protrudes from the side
surface 20 a, the protrusion may be the lowermost end portion 201 of the mobile phone 10. The
protrusion is, for example, a side key or a connector cap.
[0042]
In FIG. 10, a dotted line L is a line which passes through the center of gravity G of the mobile
telephone 10 and is perpendicular to the contact surface 150 when the mobile telephone 10 is
placed on a horizontal contact surface 150 such as a desk with the side 20a facing downward.
(Virtual line). The dashed-dotted line I is a line (virtual line) connecting the lowermost end 701 of
the elastic member 70 and the lowermost end 201 of the mobile phone 10 when it is assumed
that the excitation unit 91 does not exist.
[0043]
In FIG. 10, a region R1 is a region on one side divided by a dotted line L in the mobile phone 10.
Further, the region R2 is the region on the other side divided by the dotted line L in the mobile
phone 10. The elastic member 70 is provided on the region R1 side on the side surface 20a.
Moreover, the vibration excitation part 91 is provided in area | region R2 side in the side surface
20a.
[0044]
The excitation portion 91 is preferably provided as close as possible to the dotted line L on the
region R2 side of the side surface 20a. As a result, the load applied to the excitation unit 91 via
the piezoelectric vibration unit 60 is larger than when the excitation unit 91 is provided at a
position separated from the dotted line L on the region R2 side of the side surface 20a. Thereby,
the mobile phone 10 can be effectively utilized as a weight of a sound generator.
[0045]
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The elastic member 70 is preferably provided as far as possible from the dotted line L on the
region R1 side of the side surface 20a. As a result, even when the piezoelectric vibrating portion
60 is provided as close to the dotted line L as possible, a sufficient distance between the elastic
member 70 and the piezoelectric vibrating portion 60 is secured, and the sound generator is
stabilized on the contact surface 150. It can be placed.
[0046]
In the lowermost end 911 of the excitation portion 91, a voltage is not applied to the laminated
piezoelectric element 61, and the dotted line I is drawn when the laminated piezoelectric element
61 extends most from a state in which the laminated piezoelectric element 61 does not expand
or contract. It is better to be located on the contact surface 150 side. That is, the lowermost end
portion 911 contacts the alternate long and short dash line I when the laminated piezoelectric
element 61 is not applied with a voltage and the laminated piezoelectric element 61 extends
most from a non-stretching state or at the maximum amplitude of the laminated piezoelectric
element 61. It is preferable to project to the surface 150 side. Thereby, the contact surface 150
can be appropriately vibrated by the piezoelectric vibrating unit 60.
[0047]
In the lowermost end 911 of the excitation unit 91, when the laminated piezoelectric element 61
is contracted most from the state in which no voltage is applied to the laminated piezoelectric
element 61 and the laminated piezoelectric element 61 does not expand or contract, or the
laminated piezoelectric element 61 It is preferable to be located closer to the contact surface 150
than the alternate long and short dash line I at the minimum amplitude of That is, the lowermost
end 911 is a point at the minimum amplitude of the laminated piezoelectric element 61 when the
laminated piezoelectric element 61 is contracted most from a state in which no voltage is applied
to the laminated piezoelectric element 61 and the laminated piezoelectric element 61 does not
expand or contract. It is better to project to the contact surface 150 side than the dashed line I.
Further, the projection 92 is a dashed dotted line at the minimum amplitude of the laminated
piezoelectric element 61 when the laminated piezoelectric element 61 is contracted most from a
state in which no voltage is applied to the laminated piezoelectric element 61 and the laminated
piezoelectric element 61 does not expand or contract. It is better to be located on the housing 20
side than I. As a result, the lowermost end portion 201 and the projection 92 of the mobile phone
10 are less likely to contact the contact surface 150, and for example, depending on the type of
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coating on the housing 20, the coating may not be easily peeled off. In addition, abnormal noise
is less likely to occur between the lowermost end 201 or the protrusion 92 and the contact
surface 150.
[0048]
A commercially available stand or the like may be attached to the housing 20, for example, and
the mobile phone 10 may be erected on a contact surface such as a desk with the side surface
20a facing downward. In this case, the side surface 20a of the mobile phone 10 is supported at
two points by the excitation unit 91 and the elastic member 70, and is further supported by the
stand.
[0049]
FIGS. 11 (a), (b) and (c) are schematic diagrams for explaining the operation as a sound generator
by the mobile phone 10 according to the present embodiment. When the mobile phone 10 is
made to function as a sound generator, the cover 90 is in the first position, and the mobile phone
10 has the side surface 20a side of the housing 20 facing downward as shown in FIG. The cap 94
of the vibration unit 91 and the elastic member 70 are placed upright and placed in contact with
the contact surface 150 such as a desk. Thereby, the weight of the mobile phone 10 is given as a
load to the excitation unit 91 through the piezoelectric vibration unit 60. That is, the mobile
telephone 10 acts as a weight of the sound generator according to the present invention. In the
state shown in FIG. 11A, no voltage is applied to the laminated piezoelectric element 61, and the
laminated piezoelectric element 61 does not expand or contract.
[0050]
In this state, when the laminated piezoelectric element 61 of the piezoelectric vibration unit 60 is
driven by the reproduction sound signal, the laminated piezoelectric element 61 stretches and
vibrates. FIG. 11B exaggerates the state when the laminated piezoelectric element 61 is
stretched. The vibrating portion 91 receives a force from the piezoelectric vibrating portion 60,
and the cover portion 90 bends to make the contact surface from the housing 20 more than the
stationary state of the multilayer piezoelectric element 61 (the state shown in FIG. 11A). Project
to the 150 side. FIG. 11C exaggerates the state when the multi-layer piezoelectric element 61 is
contracted. At this time, the load of the mobile phone 10 applies the cover portion 90 to be bent,
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and the excitation portion 91 retracts toward the housing 20 side than the stationary state of the
multilayer piezoelectric element 61. Thus, by repeating the states shown in FIGS. 11 (b) and 11
(c), the excitation unit 91 takes the cap 94 from the contact surface 150 with the contact portion
to the contact surface 150 of the elastic member 70 as a fulcrum. It vibrates according to the
reproduction sound signal without being separated. If the lower end portion 201 does not
contact the contact surface 150 and the noise is generated, it may be slightly separated. The
difference between the length when the laminated piezoelectric element 61 is most extended and
the length when it is most contracted is, for example, 0.05 μm to 50 μm. Thereby, the
expansion and contraction vibration of the laminated piezoelectric element 61 is transmitted to
the contact surface 150 through the excitation portion 91 to vibrate the contact surface 150, and
the contact surface 150 functions as a vibration speaker to generate a sound from the contact
surface 150. If the difference between the length when extended most and the length when
reduced most is less than 0.05 μm, the contact surface may not be vibrated properly, while if it
exceeds 50 μm, the vibration increases. Sound generator may rattle.
[0051]
Here, as described above, the tip end portion of the cap 94 is carried with the lowermost end
portion 701 of the elastic member 70 when assuming that the vibrating portion 91 does not
exist when the laminated piezoelectric element 61 is extended most. It may be located closer to
the contact surface 150 than the line connecting the lowermost end 201 of the telephone set 10
(the dashed line I in FIG. 10). Further, the tip end portion of the cap 94 may be positioned closer
to the contact surface 150 than the imaginary line when the laminated piezoelectric element 61
is contracted most.
[0052]
Further, the distance d between the surface 20b and the tip of the projecting portion 63b shown
in FIG. 5 is in the most contracted state from the state in which the laminated piezoelectric
element 61 is not stretched and no voltage is applied to the laminated piezoelectric element 61.
It is better to be longer than the displacement amount. As a result, even in the state where the
multi-layer piezoelectric element 61 is contracted most (the state shown in FIG. 11C), the
vibration of the multi-layer piezoelectric element 61 can be prevented from contacting the
contact surface 150 without the vibration part 91 being separated from the projecting part 63 b.
Can be transmitted to
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[0053]
The arrangement locations of the excitation unit 91 and the piezoelectric vibration unit 60, the
length in the stacking direction of the stacked piezoelectric element 61, the dimensions of the
cap 94, and the like are appropriately determined so as to satisfy the above-described conditions.
[0054]
According to the sound generator according to the present embodiment, since the piezoelectric
element is used as a vibration source, the number of parts can be reduced and the number of
parts can be simplified as compared with a conventional vibration generating device having a
dynamic speaker structure. To reduce the size and weight.
Further, using the stack type stacked piezoelectric element 61 as the piezoelectric element, the
expansion and contraction vibration is transmitted along the stacking direction by the
reproduced sound signal, and the expansion and contraction vibration is transmitted to the
contact surface 150. The vibration transmission efficiency in the deformation direction) is good,
and the contact surface 150 can be vibrated efficiently. In addition, since the laminated
piezoelectric element 61 is brought into contact with the excitation portion 91 through the
covering member 63, breakage of the laminated piezoelectric element 61 can also be prevented.
In addition, when the portable telephone 10 is placed horizontally and the cap 94 of the
excitation unit 91 is in contact with the contact surface 150, the weight of the portable telephone
10 is applied as a load to the cap 94 through the piezoelectric vibrating unit 60. The elastic
vibration of the piezoelectric vibrating portion 60 can be efficiently transmitted to the contact
surface 150 by reliably contacting the contact surface 150.
[0055]
Further, according to the sound generator according to the present embodiment, when the sound
generator is not used to generate sound, the piezoelectric vibration unit 60 and the excitation
unit 91 are not operated by operating the cover unit 90. It can be in a contact state. By doing so,
the piezoelectric vibrating portion 60 is covered by the cover portion 90, so that it is protected
from external impact. Furthermore, according to the sound generator according to the present
embodiment, the switching between the first position and the second position by the
displacement of the cover 90 is interlocked with the switch function of the sound signal to the
piezoelectric element 61. Therefore, when the sound generator is not used to generate sound, the
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piezoelectric vibration unit 60 and the excitation unit 91 are not in contact with each other by
displacing the cover unit 90 to the second position. No sound signal can be input. As described
above, by interlocking the operation of the cover 90 and the switch function of the sound signal
to the piezoelectric element 61, simplification of the operation can be realized as compared with
the case where the cover 90 and the switch are separately provided. it can.
[0056]
Further, since the sound generator according to the present embodiment can mainly transmit the
vibration of the laminated piezoelectric element directly to the contact surface, it is different from
the case of transmitting the vibration of the laminated piezoelectric element to another elastic
body When generating sound, it does not depend on the limit frequency on the high frequency
side where other elastic bodies can vibrate. The limit frequency on the high frequency side at
which the other elastic body can vibrate is the reciprocal of the shortest time from the time from
the deformation of the other elastic body by the piezoelectric element to the return to the
deformable state. In consideration of this, it is preferable that the weight of the sound generator
according to the present embodiment has a rigidity (bending strength) that does not cause
bending deformation due to deformation of the piezoelectric element.
[0057]
The present invention is not limited to the above embodiment, and many modifications and
variations are possible. For example, the structure for fixing the piezoelectric vibration unit 60 to
the holding unit 100 is not limited to that shown in FIG. As shown in FIGS. 12A to 12C, the
piezoelectric vibrating unit 60 may be held by the holding unit 100. The holding portion 100
shown in FIG. 12A has a wide slit 101a opened to the surface 20b and a narrow slit 101b
continuous to the slit 101a. The multilayer piezoelectric element 61 is disposed at one end of the
slit 101 b having a narrow width, and the side surface is fixed to the slit 101 b via the adhesive
102. Further, the wide slit 101 a is filled with a filler 103 such as silicone rubber or gel which
does not hinder the expansion and contraction operation of the multilayer piezoelectric element
61 in the gap with the multilayer piezoelectric element 61. By holding the piezoelectric vibration
unit 60 in the holding unit 100 as described above, the mobile phone 10 can be more reliably
waterproofed without using a waterproof packing such as an O-ring. Further, by covering the
portion of the laminated piezoelectric element 61 projecting from the surface 20 b with an
insulating cap, the laminated piezoelectric element 61 can be reliably insulated.
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[0058]
The holding portion 100 shown in FIG. 12B has a tapered slit 101c expanding toward the surface
20b, and a narrow slit 101d continuous with the tapered slit 101c. The laminated piezoelectric
element 61 is disposed at one end of the slit 101 d in a narrow width, and the side surface is
fixed to the slit 101 d via the adhesive 102. Further, in the tapered slit 101 c, a filler 103 such as
silicone rubber or gel that does not interfere with the expansion and contraction operation of the
multilayer piezoelectric element 61 is filled in the gap with the multilayer piezoelectric element
61. According to this structure, in addition to the same effect as the holding unit 100 of FIG. 12A,
since the tapered slit 101c is provided, the assembly of the laminated piezoelectric element 61 to
the holding unit 100 is easy. There are advantages to
[0059]
The holding portion 100 shown in FIG. 12C has the slit 101 having a uniform width as in the
above embodiment, but the end face of the laminated piezoelectric element 61 on the one end
portion side is through the adhesive 102. It is fixed to the slit 101. In addition, an O-ring 62 is
disposed at an appropriate position of the laminated piezoelectric element 61 in the slit 101.
Such a holding mode of the laminated piezoelectric element 61 is, in particular, as shown in FIG.
4 in the case where the lead wire connecting portion is formed on the side surface electrode as
shown in FIG. It is advantageous in terms of etc.
[0060]
Further, in FIG. 8, an LPF having the same characteristic as the LPF 123 may be provided
between the signal processing circuit 121 and the booster circuit 122. Further, in FIG. 8, the
function of the LPF 123 may be provided to an equalizer or the like of the signal processing
circuit 121 and the LPF 123 may be omitted.
[0061]
In the above embodiment, the cover 90 is disposed on the side surface 20a of the housing 20,
and the excitation unit 91 protrudes from the side 20a. However, the present invention is not
limited to this. Depending on the dimensions of the housing 20 and the dimensions of the
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piezoelectric vibrating unit 60, for example, the piezoelectric vibrating unit 60 and the cover unit
90 may be provided on the battery lid 21, and the vibrating unit 91 may protrude from the
battery lid 21.
[0062]
Moreover, the cover part 90 is not restricted to what slides the side surface 20a top in a
longitudinal direction, as shown in FIG. For example, as shown in FIG. 13, the cover 90 may be
circular, and may be configured to rotate in the direction of the arrow 910 for operation.
[0063]
FIG. 14 is a view showing the operation of the circular cover portion. FIG. 14A shows the contact
state between the piezoelectric vibration unit 60 and the excitation unit 91. At this time, the
cover unit 90 is in the first position. FIG.14 (b) is AA sectional drawing of Fig.14 (a). Further, FIG.
14C shows a non-contact state between the piezoelectric vibration unit 60 and the excitation unit
91, and at this time, the cover unit 90 is in the second position. FIG. 14D is a cross-sectional view
taken along line A-A of FIG. The user of the mobile phone 10 operates the projection 92 to
displace the cover 90 (excitation unit 91) in the rotational direction, thereby switching between
the first position and the second position, thereby the piezoelectric vibration unit It is possible to
switch between the contact state and the non-contact state between 60 and the excitation unit
91. The first position of FIG. 14A is used when the mobile phone 10 generates a sound. That is,
as shown in FIG. 14B, since the piezoelectric vibrating portion 60 and the vibrating portion 91
are in contact, the vibration of the piezoelectric element is transmitted to the contact surface
such as a desk via the vibrating portion 91. Ru. On the other hand, the second position in FIG.
14C is used when the mobile phone 10 does not generate a sound. In this case, the vibration of
the piezoelectric element is not transmitted to the contact surface because the piezoelectric
vibrating portion 60 and the vibrating portion 91 are not in contact with each other as shown in
FIG. Furthermore, in the non-contact state, the piezoelectric vibrating portion 60 is protected by
the cover portion 90. Therefore, for example, even if the cellular phone 10 falls and an impact is
applied to the side surface 20a from the drop location, the cover 90 receives an impact, so that
the piezoelectric vibrating portion 60 can be protected from the impact when it is dropped.
[0064]
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In addition, the circular cover portion 90 functions as a switch for inputting a sound signal to the
piezoelectric element 61. As shown in FIG. 14 (b), the circular cover 90 is, for example, a
conductive metal on the opposite side of the excitation unit 91 across the rotation axis of the
cover 90 and on the inside of the housing 20. And a switch unit 93 having the Further, the
holding member 210 which is a part of the housing 20 for holding the cover 90 has two
terminals which become a part of a circuit for inputting a sound signal to the piezoelectric
element 61 on the contact surface 210 a. Then, at the first position of the cover portion 90, as
shown in FIG. 14B, the switch portion 93 contacts the contact surface 210a, and the two
terminals provided on the contact surface 210a are conductive metal of the switch portion 93.
Connected through. Then, the circuit for inputting a sound signal to the piezoelectric element 61
conducts, and as a result, the signal is input to the piezoelectric element 61, the piezoelectric
vibration unit 60 is driven, and the vibration is transmitted to the contact surface via the
vibration unit 91. Ru. Thus, the mobile phone 10 generates a sound from the touch surface. On
the other hand, when the cover portion 90 is displaced to the second position and the
piezoelectric vibrating portion 60 and the vibrating portion 91 are not in contact with each other,
this circuit does not conduct, so no sound signal is input to the piezoelectric element 61. The
vibrating unit 60 is not driven. Therefore, the mobile phone 10 does not generate sound.
[0065]
Moreover, a cover part is not restricted to the thing of the shape shown in FIG. 6 or FIG. For
example, as shown in FIG. 15A, the cover 90 may be provided, at both ends of the vibration
excitation unit 91, with a narrow portion 95 whose thickness is smaller than the thickness of the
cover 90. The provision of the constricted portion 95 facilitates the vibration of the vibrating
portion 91, so that the vibration of the piezoelectric element 61 can be transmitted to the contact
surface 150 more efficiently. Also, for example, as shown in FIG. 15B, the cover 90 may include a
tapered portion 96 on the side of the piezoelectric vibrating portion 60 in the vibrating portion
91. By providing the tapered portion 96, when displacing the cover portion 90 from the second
position to the first position, the piezoelectric vibrating portion 60 and the vibrating portion 91
do not interfere with each other, and the piezoelectric vibrating portion reliably. The cover 90
can be smoothly displaced so that the cover 60 and the cover 90 are in contact with each other.
[0066]
Furthermore, the switch unit 93 is not limited to the above embodiment. For example, as the
switch unit 93, a detection switch is used to detect whether the end portion of the cover unit 90
having the switch unit 93 is in contact with the end surface 901a, that is, whether the cover unit
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90 is in the first position. , And the cover 90 may be provided. In this case, when the detection
switch detects that the cover 90 is at the first position, a sound signal is input to the piezoelectric
element 61 and the detection switch does not detect that the cover 90 is at the first position.
That is, when the cover portion 90 is in the second position, the piezoelectric element 61 is
configured not to input a sound signal.
[0067]
In addition, for example, the excitation unit 91 may omit the cap 94, and the tip end surface of
the excitation unit 91 may be in contact with the contact surface directly or via a vibration
transmission member made of an insulating member or the like. Also, the protrusion 92 may be
omitted. In this case, the user can move the cover 90 by moving the vibration unit 91 with a
finger, for example.
[0068]
Moreover, in said embodiment, although the to-be-contacted member is a desk and it
demonstrated that the contact surface was a horizontal contact surface of a desk, this invention is
not limited to this. The contact surface may not be horizontal. The contact surface may be, for
example, a surface perpendicular to the ground of the desk. As a contacted member which has a
field perpendicular to the ground, for example, a partition for separating space is mentioned.
[0069]
Further, in the above embodiment, the sound generator is mounted on the mobile phone 10 and
the mobile phone 10 functions as a weight, but the weight is not limited to this. For example, a
variety of electronic devices such as portable music players, stationary TVs, teleconferencing
systems, laptop computers, projectors, wall clocks / wall TVs, alarm clocks, photo frames, etc. can
be used as a weight to generate sound in these electronic devices Can also be mounted.
[0070]
DESCRIPTION OF SYMBOLS 10 mobile phone 20 case 20a side 20b surface 21 battery lid 30
panel 40 input unit 50 display unit 60 piezoelectric vibration unit 61 laminated piezoelectric
element (piezoelectric element) 62 O ring 63 cover member 90 cover portion 91 excitation
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portion 92 protrusion portion 93 Switch part 94 Cap part 95 Constricted part 96 Tapered part
100 Holding part 101 Slit 110 Wireless communication part 120 Piezoelectric element drive
part 121 Signal processing circuit 122 Boost circuit 123 Low pass filter (LPF) 130 Control part
150 Contact surface 900, 901 Holding part 901a end face
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