U.S. patent application number 11/428012 was filed with the patent office on 2006-10-26 for piezoelectric composite device, method of manufacturing same, method of controlling same, input-output device, and electronic device.
Invention is credited to Shigeaki Maruyama, Ivan Poupyrev, Junichi Sekine.
Application Number | 20060238069 11/428012 |
Document ID | / |
Family ID | 35756711 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060238069 |
Kind Code |
A1 |
Maruyama; Shigeaki ; et
al. |
October 26, 2006 |
PIEZOELECTRIC COMPOSITE DEVICE, METHOD OF MANUFACTURING SAME,
METHOD OF CONTROLLING SAME, INPUT-OUTPUT DEVICE, AND ELECTRONIC
DEVICE
Abstract
Disclosed herein is a piezoelectric composite device including:
a feeding electrode; a common electrode; a signal detecting
electrode; a first piezoelectric element joined between the feeding
electrode and the common electrode; and a second piezoelectric
element joined between the common electrode and the signal
detecting electrode; a predetermined voltage being supplied between
the feeding electrode and the common electrode; and a force
detection signal based on an external force being extracted from
the detecting electrode.
Inventors: |
Maruyama; Shigeaki;
(Kanagawa, JP) ; Sekine; Junichi; (Kanagawa,
JP) ; Poupyrev; Ivan; (Tokyo, JP) |
Correspondence
Address: |
SONNENSCHEIN NATH & ROSENTHAL LLP
P.O. BOX 061080
WACKER DRIVE STATION, SEARS TOWER
CHICAGO
IL
60606-1080
US
|
Family ID: |
35756711 |
Appl. No.: |
11/428012 |
Filed: |
June 30, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11193238 |
Jul 29, 2005 |
|
|
|
11428012 |
Jun 30, 2006 |
|
|
|
Current U.S.
Class: |
310/316.01 |
Current CPC
Class: |
H01L 41/0825 20130101;
G06F 2203/04105 20130101; H01L 41/273 20130101; H01L 41/0474
20130101; G06F 3/016 20130101; H01L 41/083 20130101; G06F 3/011
20130101; H03K 17/9643 20130101 |
Class at
Publication: |
310/316.01 |
International
Class: |
H01L 41/107 20060101
H01L041/107 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2004 |
JP |
P2004-227053 |
Claims
1. An electronic device comprising: an input-output device,
including: input means for detecting a contact position of an
operating object and outputting input information; and tactile
sense providing and information determining means for providing a
tactile sense to said operating object operating said input means,
and detecting a force at the contact position of said operating
object and determining said input information; wherein said tactile
sense providing and information determining means of said
input-output device includes a piezoelectric composite device;
wherein said piezoelectric composite device including: a feeding
electrode; a common electrode; a signal detecting electrode; a
first piezoelectric element joined between said feeding electrode
and said common electrode; and a second piezoelectric element
joined between said common electrode and said signal detecting
electrode; wherein a predetermined voltage being supplied between
said feeding electrode and said common electrode; and wherein a
force detection signal based on an external force being extracted
from said detecting electrode.
2. The electronic device as claimed in claim 1, further comprising
a control device connected to each of said feeding electrode, said
common electrode, and said signal detecting electrode, wherein said
control device supplies power between said feeding electrode and
said common electrode according to a preset control signal and
detects a force detection signal from said signal detecting
electrode.
3. The electronic device as claimed in claim 2, wherein said
control device controls feeding to said feeding electrode on a
basis of the force detection signal obtained from said signal
detecting electrode.
4. The electronic device as claimed in claim 2, further comprising
display means for displaying said input information, wherein said
control device detects a force of the operating object selecting an
input item displayed by said display means, and determines that
said input item is selected on a basis of the detected force of
said operating object.
5. The electronic device as claimed in claim 4, wherein said
control device determines that said input item is selected on a
basis of the force detection signal obtained from said signal
detecting electrode, and then gives a tactile stimulus to said
operating object by controlling feeding to said feeding electrode.
Description
RELATED APPLICATION DATA
[0001] This application is divisional of U.S. patent application
Ser. No. 11/193,238, filed Jul. 29, 2005, which is incorporated
herein by reference to the extent permitted by law. This
application claims the benefit of priority to Japanese Patent
Application No. JP 2004-227053 filed in the Japanese Patent Office
on Aug. 3, 2004, which also is incorporated herein by reference to
the extent permitted by law.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a piezoelectric composite
device, a method of manufacturing the same, a method of controlling
the same, an input-output device, and an electronic device that are
suitable for application to portable telephones, digital cameras,
portable terminals, remote controllers and the like having a
tactile input function.
[0003] The present invention relates particularly to a
piezoelectric composite device including a first piezoelectric
element joined between a feeding electrode and a common electrode;
and a second piezoelectric element joined between the common
electrode and a signal detecting electrode; wherein a predetermined
voltage is supplied between the feeding electrode and the common
electrode, and a force detection signal based on an external force
is extracted from the detecting electrode, so that the
piezoelectric composite device can be provided which combines a
piezoelectric bimorph type actuator vibrating on the basis of the
predetermined voltage supplied between the feeding electrode and
the common electrode with a force detecting sensor outputting the
force detection signal based on the external force.
[0004] There have recently been more and more cases where users
(operators) use a digital camera having multiple operation modes to
photograph a subject, and capture various contents into a portable
terminal such as a portable telephone, a PDA (Personal Digital
Assistant) or the like and use the various contents. The digital
camera and the portable terminal and the like have an input-output
device. A touch panel that combines input section such as a
keyboard, various keys, a JOG dial and the like with a display
unit, for example, is often used for the input-output device.
[0005] In addition, an input-output device combined with an
actuator has been developed. In the actuator, piezoelectric
elements having different amounts of distortion in two or more
layers, or piezoelectric elements and a non-piezoelectric element
are bonded to each other, and a bend deformation of the bonded
object which deformation is caused by a difference in the amounts
of distortion of both the elements when a voltage is applied to the
piezoelectric elements is used dynamically. So-called bimorph
actuators, unimorph actuators, disk actuators and the like
(hereinafter referred to collectively as piezoelectric bimorph type
actuators) are often used as the actuator.
[0006] FIG. 26 is a perspective view of an example of structure of
a multilayer piezoelectric bimorph type actuator 300 according to a
conventional example. The multilayer piezoelectric bimorph type
actuator 300 shown in FIG. 26 is formed by bonding together
laminated piezoelectric substance groups 4a and 4b that elongate
and contract respectively in opposite directions to each other on
both sides of a central electrode 13 as a neutral surface of bend
deformation. A metal sheet of stainless steel or the like is
generally used for the central electrode 13. Leads L1 and L2 are
connected to the central electrode 13 and an upper part surface
electrode 11 or a lower part surface electrode 12. The upper part
surface electrode 11 and the lower part surface electrode 12 are
used in a state of being short-circuited by a short-circuit line
L0. The actuator 300 is characterized by allowing lower-voltage
driving as compared with a single-layer piezoelectric actuator.
[0007] FIG. 27 is a sectional view showing an example of a
laminated structure of the multilayer piezoelectric bimorph type
actuator 300. FIG. 27 is a sectional view taken along a line Y1-Y2
of FIG. 26 showing the actuator 300. The multilayer piezoelectric
bimorph type actuator 300 shown in FIG. 27 has the laminated
piezoelectric substance group 4a and the laminated piezoelectric
substance group 4b. Piezoelectric elements within the same
laminated piezoelectric substance group 4a deform in the same
direction, and piezoelectric elements within the same laminated
piezoelectric substance group 4b deform in the same direction. The
laminated piezoelectric substance group 4a and the laminated
piezoelectric substance group 4b deform in opposite directions to
each other. The actuator 300 thereby performs bend deformation. In
order to drive the actuator 300, power is supplied with the surface
electrodes (upper and lower) 11 and 12 at outermost surfaces
short-circuited and with the leads L1 and L2 connected to the upper
part surface electrode 11 or the lower part surface electrode 12
and the central electrode 13, as shown in FIG. 26.
[0008] The actuator 300 can be used as a force detecting sensor as
reverse action of the actuator 300. In this case, a voltage
generated by a deformation of the actuator 300 due to an external
force is taken out from the above-mentioned leads L1 and L2 to the
outside. Each of the laminated piezoelectric substance groups 4a
and 4b includes piezoelectric elements in the form of layers and
internal electrode layers (main electrodes) IE1 to IE16 formed such
that the piezoelectric elements are sandwiched between the internal
electrode layers IE1 to IE16. These internal electrode layers IE1
to IE16 are connected within the actuator. Generally, in this
internal connection, alternate layers are connected to each other
by a method using via holes or an actuator side part formed with
the internal electrodes exposed, for example, and the piezoelectric
elements are used in electrically parallel connection with each
other. The internal connection cannot be changed from the outside.
This is because the internal connection is not drawn out to the
outside of the actuator.
[0009] In relation to an electronic device having this kind of
piezoelectric actuator, for example, in Japanese Patent Laid-Open
No. 2004-94389 (pages 4 and 5, FIG. 11) (hereinafter referred to as
Patent Document 1), discloses an input-output device and an
electronic device. This electronic device includes an input-output
device having a multilayer piezoelectric bimorph type actuator and
a touch panel. The multilayer piezoelectric bimorph type actuator
feeds back a different tactile sense to a user through the touch
panel according to a type of information. The electronic device
being thus formed, when the user performs an input operation on the
touch panel using the sense of touch, a tactile feedback in
response to the input operation in accordance with a type of
information can be surely provided to the user.
SUMMARY OF THE INVENTION
[0010] The input-output device using the multilayer piezoelectric
bimorph type actuator 300 according to the conventional example has
the following problems.
[0011] i. When the multilayer piezoelectric bimorph type actuator
300 is used as a force detecting sensor, the force detecting sensor
needs to be formed by a discrete structure separate from and
independent of a structure in which the multilayer piezoelectric
bimorph type actuator 300 is used as an actuator. Hence, the two
structures of the force detecting sensor and the actuator need to
be attached to the input-output device, thus requiring more
mounting space as compared with a case where the structures are
integrated into one structure.
[0012] ii. When an electronic device having an input-output device
as disclosed in Patent Document 1 provides a tactile sense to a
user and detects the pressing force of the user or the like at the
same time, and the multilayer piezoelectric bimorph type actuator
300 is to be applied, it is desirable that the function of a force
detecting sensor and the function of an actuator be used
simultaneously. However, a difficulty is involved in integrating
the two structures described above into one structure. It is
therefore difficult to realize the two functions by one structure
when the structure of the multilayer piezoelectric bimorph type
actuator 300 in the conventional form is used as it is.
[0013] iii. Incidentally, when the function of a force detecting
sensor and the function of an actuator are to be used
simultaneously with the structure of the multilayer piezoelectric
bimorph type actuator 300 in the conventional form used as it is, a
command voltage for driving the actuator is included in a voltage
detected by the force detecting sensor. As compared with this
driving command voltage, the voltage (sensor output signal) varied
by external force is low, so that the separation of the voltages is
technically difficult. In addition to this, the addition of a
complex circuit is expected, which will be disadvantageous from a
viewpoint of size and cost of the actuator.
[0014] Accordingly, the present invention solves the
above-described problems, and it is desirable to provide a
piezoelectric composite device, a method of manufacturing the same,
a method of handling the same, a method of controlling the same, an
input-output device, and an electronic device that enable a
laminate in which one or more lead electrodes and piezoelectric
elements are laminated to function both as an actuator and as a
force detecting sensor.
[0015] According to an embodiment of the present invention, there
is provided a piezoelectric composite device including: a feeding
electrode; a common electrode; a signal detecting electrode; a
first piezoelectric element joined between the feeding electrode
and the common electrode; and a second piezoelectric element joined
between the common electrode and the signal detecting electrode; a
predetermined voltage being supplied between the feeding electrode
and the common electrode; and a force detection signal based on an
external force being extracted from the detecting electrode.
[0016] The first piezoelectric composite device according to the
embodiment of the present invention includes the first
piezoelectric element joined between the feeding electrode and the
common electrode, and the second piezoelectric element joined
between the common electrode and the signal detecting electrode.
With this laminated structure as a precondition, a predetermined
voltage is supplied between the feeding electrode and the common
electrode, and a force detection signal based on an external force
is extracted from the detecting electrode.
[0017] It is thus possible to provide the piezoelectric composite
device which combines a piezoelectric bimorph type actuator
vibrating on the basis of the predetermined voltage supplied
between the feeding electrode and the common electrode, and a force
detecting sensor outputting the force detection signal based on the
external force.
[0018] According to an embodiment of the present invention, there
is provided a first method of manufacturing a piezoelectric
composite device, the method including: a step of joining a first
piezoelectric element between a feeding electrode and a common
electrode; a step of joining a second piezoelectric element between
the common electrode and a signal detecting electrode; a step of
connecting leads for supplying a predetermined voltage to each of
the feeding electrode and the common electrode; and a step of
connecting leads for extracting a force detection signal based on
an external force to each of the common electrode and the signal
detecting electrode.
[0019] According to the first method of manufacturing a
piezoelectric composite device according to the embodiment of the
present invention, it is possible to manufacture the piezoelectric
composite device which combines a piezoelectric bimorph type
actuator vibrating on the basis of the predetermined voltage
supplied between the feeding electrode and the common electrode,
and a force detecting sensor outputting the force detection signal
based on the external force.
[0020] According to an embodiment of the present invention, there
is provided a first method of controlling a piezoelectric composite
device, the piezoelectric composite device including a feeding
electrode, a common electrode, a signal detecting electrode, a
first piezoelectric element joined between the feeding electrode
and the common electrode, and a second piezoelectric element joined
between the common electrode and the signal detecting electrode,
wherein a control device connected to each of the feeding
electrode, the common electrode, and the signal detecting electrode
is provided, and the control device supplies power between the
feeding electrode and the common electrode according to a preset
control signal and detects a force detection signal from the signal
detecting electrode.
[0021] According to the first method of controlling a piezoelectric
composite device according to the embodiment of the present
invention, the control device is connected to each of the feeding
electrode, the common electrode, and the signal detecting
electrode. The control device supplies power between the feeding
electrode and the common electrode according to a preset control
signal and detects a force detection signal from the signal
detecting electrode.
[0022] Thus, an actuator function can be performed by the first
piezoelectric element joined between the feeding electrode and the
common electrode, and a force detecting function can be performed
by the second piezoelectric element joined between the common
electrode and the signal detecting electrode. In addition, when
power is supplied to each of the feeding electrode, the common
electrode, and the signal detecting electrode, an actuator function
can be performed by the first piezoelectric element and the second
piezoelectric element. It is therefore possible to perform function
switching control in which the second piezoelectric element made to
perform the force detecting function is made to function as an
actuator according to circumstances.
[0023] According to an embodiment of the present invention, there
is provided a first input-output device including: input section
for detecting a contact position of an operating object and
outputting input information; and tactile sense providing and
information determining section for providing a tactile sense to
the operating object operating the input section, and detecting a
force at the contact position of the operating object and
determining the input information; the tactile sense providing and
information determining section having a piezoelectric composite
device; the piezoelectric composite device including a feeding
electrode, a common electrode, a signal detecting electrode, a
first piezoelectric element joined between the feeding electrode
and the common electrode, and a second piezoelectric element joined
between the common electrode and the signal detecting electrode; a
predetermined voltage being supplied between the feeding electrode
and the common electrode; and a force detection signal based on an
external force being extracted from the detecting electrode.
[0024] According to the first input-output device in accordance
with the embodiment of the present invention, the first
piezoelectric composite device according to an embodiment of the
present invention is applied to the tactile sense providing and
information determining section. The first piezoelectric composite
device includes a feeding electrode, a common electrode, a signal
detecting electrode, a first piezoelectric element joined between
the feeding electrode and the common electrode, and a second
piezoelectric element joined between the common electrode and the
signal detecting electrode. With this as a precondition, the input
section detects a contact position of an operating object and
outputs input information. The tactile sense providing and
information determining section provides a tactile sense to the
operating object operating the input section, and detects a force
at the contact position of the operating object and determines the
input information.
[0025] Hence, since a part of the piezoelectric composite device
functioning as a piezoelectric bimorph type actuator can be used as
a force detecting sensor for determining the information, the
function of the actuator and the function of the force detecting
sensor can be used at the same time. In addition, as compared with
a case where the actuator and the force detecting sensor are
provided separately from each other, a mounting space is shared and
thus the input-output device can be made more compact.
[0026] According to an embodiment of the present invention, there
is provided a first electronic device including an input-output
device; the input-output device including input section for
detecting a contact position of an operating object and outputting
input information, and tactile sense providing and information
determining section for providing a tactile sense to the operating
object operating the input section, and detecting a force at the
contact position of the operating object and determining the input
information; the tactile sense providing and information
determining section of the input-output device having a
piezoelectric composite device; the piezoelectric composite device
including a feeding electrode, a common electrode, a signal
detecting electrode, a first piezoelectric element joined between
the feeding electrode and the common electrode, and a second
piezoelectric element joined between the common electrode and the
signal detecting electrode; a predetermined voltage being supplied
between the feeding electrode and the common electrode; and a force
detection signal based on an external force being extracted from
the detecting electrode.
[0027] According to the first electronic device in accordance with
the embodiment of the present invention, the first piezoelectric
composite device according to an embodiment of the present
invention is applied to the tactile sense providing and information
determining section of the first input-output device. The first
piezoelectric composite device includes a feeding electrode, a
common electrode, a signal detecting electrode, a first
piezoelectric element joined between the feeding electrode and the
common electrode, and a second piezoelectric element joined between
the common electrode and the signal detecting electrode. With this
as a precondition, the input section detects a contact position of
an operating object and outputs input information. The tactile
sense providing and information determining section provides a
tactile sense to the operating object operating the input section,
and detects a force at the contact position of the operating object
and determines the input information.
[0028] Hence, since a part of the first piezoelectric composite
device functioning as a piezoelectric bimorph type actuator can be
used as a force detecting sensor, the function of the actuator and
the function of the force detecting sensor can be used at the same
time. In addition, as compared with a case where the actuator and
the force detecting sensor are provided separately from each other,
a mounting space is shared and thus the electronic device can be
made more compact.
[0029] According to an embodiment of the present invention, there
is provided a second piezoelectric composite device including: a
first laminate and a second laminate formed by laminating a lead
electrode and one or more piezoelectric elements; and a third
laminate having another lead electrode, and having one or more
piezoelectric elements laminated between the first laminate and the
second laminate.
[0030] According to the second piezoelectric composite device in
accordance with the embodiment of the present invention, when power
is supplied to the lead electrodes of the first laminate and the
second laminate, the one or more piezoelectric elements can be
vibrated, so that the piezoelectric composite device can be made to
function as a piezoelectric bimorph type actuator. In addition,
when a force is applied to the third laminate, a force detection
signal can be output from the lead electrode of the third laminate,
so that the piezoelectric composite device can be made to function
as a force detecting sensor. Further, a composite function
combining the above-described functions can be realized. It is
thereby possible to provide a multifunction actuator of a low
voltage driving type or the like that enables both the functions to
be used simultaneously.
[0031] According to an embodiment of the present invention, there
is provided a second method of manufacturing a piezoelectric
composite device, the method including: a step of forming a
laminate by one or more piezoelectric elements and lead electrodes;
a step of electrically dividing the laminate to demarcate at least
three laminates; a step of drawing out electrodes from a
piezoelectric element situated in a central laminate of the
demarcated laminates; and a step of drawing out electrodes from
piezoelectric elements of the other laminates situated on both
sides of the central laminate.
[0032] According to the second method of manufacturing a
piezoelectric composite device in accordance with the embodiment of
the present invention, a piezoelectric bimorph type actuator and a
force detecting sensor can be formed within an identical structure.
It is thereby possible to manufacture a multifunction actuator of a
low voltage driving type or the like that enables both the function
of the actuator and the function of the force detecting sensor to
be used simultaneously. In addition, as compared with a case where
the actuator and the force detecting sensor are provided separately
from each other, a mounting space is shared and thus the electronic
device can be made more compact.
[0033] According to an embodiment of the present invention, there
is provided a second method of controlling a piezoelectric
composite device, the piezoelectric composite device including a
first laminate and a second laminate formed by laminating a lead
electrode and one or more piezoelectric elements, and a third
laminate having another lead electrode, and having one or more
piezoelectric elements laminated between the first laminate and the
second laminate, wherein a control device connected to the lead
electrode of each of the first laminate, the second laminate, and
the third laminate is provided, and the control device supplies
power to the lead electrode of each of the first laminate and the
second laminate according to a preset control signal, and supplies
power to the lead electrode of the third laminate or detects a
force detection signal from the lead electrode of the third
laminate.
[0034] According to the second method of controlling a
piezoelectric composite device according to the embodiment of the
present invention, the control device is connected to the lead
electrode of each of the first laminate, the second laminate, and
the third laminate formed by laminating a lead electrode and one or
more piezoelectric elements. The control device supplies power to
the lead electrode of each of the first laminate and the second
laminate according to a preset control signal, and detects a force
detection signal from the lead electrode of the third laminate.
[0035] Thus, an actuator function can be performed by the first
laminate and the second laminate, and a force detecting function
can be performed by the third laminate. In addition, when power is
supplied to the lead electrode of each of the first laminate, the
second laminate, and the third laminate, an actuator function can
be performed by the first laminate, the second laminate, and the
third laminate. It is therefore possible to perform function
switching control in which the piezoelectric element or the
piezoelectric elements of the third laminate made to perform the
force detecting function is or are made to function as an actuator
according to circumstances.
[0036] According to an embodiment of the present invention, there
is provided a second input-output device including: input section
for detecting a contact position of an operating object and
outputting input information; and tactile sense providing and
information determining section for providing a tactile sense to
the operating object operating the input section, and detecting a
force at the contact position of the operating object and
determining the input information; the tactile sense providing and
information determining section having a piezoelectric composite
device; the piezoelectric composite device including a first
laminate and a second laminate formed by laminating a lead
electrode and one or more piezoelectric elements, and a third
laminate having another lead electrode and having one or more
piezoelectric elements laminated between the first laminate and the
second laminate.
[0037] According to the second input-output device in accordance
with the embodiment of the present invention, the piezoelectric
composite device according to an embodiment of the present
invention is applied to the tactile sense providing and information
determining section. The piezoelectric composite device includes a
first laminate and a second laminate formed by laminating a lead
electrode and one or more piezoelectric elements, and a third
laminate having another lead electrode and having one or more
piezoelectric elements laminated between the first laminate and the
second laminate. With this as a precondition, the input section
detects a contact position of an operating object and outputs input
information. The tactile sense providing and information
determining section provides a tactile sense to the operating
object operating the input section, and detects a force at the
contact position of the operating object and determines the input
information.
[0038] Hence, since a part of the piezoelectric composite device
functioning as a piezoelectric bimorph type actuator can be used as
a force detecting sensor for determining the information, the
function of the actuator and the function of the force detecting
sensor can be used at the same time. In addition, as compared with
a case where the actuator and the force detecting sensor are
provided separately from each other, a mounting space is shared and
thus the input-output device can be made more compact.
[0039] According to an embodiment of the present invention, there
is provided a second electronic device including an input-output
device; the input-output device including input section for
detecting a contact position of an operating object and outputting
input information, and tactile sense providing and information
determining section for providing a tactile sense to the operating
object operating the input section, and detecting a force at the
contact position of the operating object and determining the input
information; the tactile sense providing and information
determining section of the input-output device having a
piezoelectric composite device; the piezoelectric composite device
including a first laminate and a second laminate formed by
laminating a lead electrode and one or more piezoelectric elements,
and a third laminate having another lead electrode and having one
or more piezoelectric elements laminated between the first laminate
and the second laminate.
[0040] According to the second electronic device in accordance with
the embodiment of the present invention, the second piezoelectric
composite device according to an embodiment of the present
invention is applied to the tactile sense providing and information
determining section of the input-output device. The piezoelectric
composite device includes a first laminate and a second laminate
formed by laminating a lead electrode and one or more piezoelectric
elements, and a third laminate having another lead electrode and
having one or more piezoelectric elements laminated between the
first laminate and the second laminate. With this as a
precondition, the input section detects a contact position of an
operating object and outputs input information. The tactile sense
providing and information determining section provides a tactile
sense to the operating object operating the input section, and
detects a force at the contact position of the operating object and
determines the input information.
[0041] Hence, since a part of the piezoelectric composite device
functioning as a piezoelectric bimorph type actuator can be used as
a force detecting sensor, the function of the actuator and the
function of the force detecting sensor can be used at the same
time. In addition, as compared with a case where the actuator and
the force detecting sensor are provided separately from each other,
a mounting space is shared and thus the electronic device can be
made more compact.
[0042] The first piezoelectric composite device according to an
embodiment of the present invention includes: a first piezoelectric
element joined between a feeding electrode and a common electrode;
and a second piezoelectric element joined between the common
electrode and a signal detecting electrode; a predetermined voltage
being supplied between the feeding electrode and the common
electrode; and a force detection signal based on an external force
being extracted from the detecting electrode.
[0043] With this constitution, it is possible to provide the
piezoelectric composite device which combines a piezoelectric
bimorph type actuator vibrating on the basis of the predetermined
voltage supplied between the feeding electrode and the common
electrode, and a force detecting sensor outputting the force
detection signal based on the external force. Thus, when only the
force detection signal based on the external force modulated by the
predetermined voltage supplied between the feeding electrode and
the common electrode can be extracted, it is possible to provide a
multifunction actuator of a low voltage driving type or the like
that enables the function of the actuator and the function of the
force detecting sensor to be used simultaneously.
[0044] The first method of manufacturing a piezoelectric composite
device according to an embodiment of the present invention
includes: joining a first piezoelectric element between a feeding
electrode and a common electrode; then joining a second
piezoelectric element between the common electrode and a signal
detecting electrode; then connecting leads for supplying a
predetermined voltage to each of the feeding electrode and the
common electrode; and then connecting leads for extracting a force
detection signal based on an external force to each of the common
electrode and the signal detecting electrode.
[0045] With this constitution, it is possible to manufacture the
piezoelectric composite device which combines a piezoelectric
bimorph type actuator vibrating on the basis of the predetermined
voltage supplied between the feeding electrode and the common
electrode, and a force detecting sensor outputting the force
detection signal based on the external force. Thus, when only the
force detection signal based on the external force modulated by the
predetermined voltage supplied between the feeding electrode and
the common electrode can be extracted, it is possible to
manufacture a multifunction actuator of a low voltage driving type
or the like that enables the function of the actuator and the
function of the force detecting sensor to be used
simultaneously.
[0046] In the first method of controlling a piezoelectric composite
device, a control device connected to each of a feeding electrode,
a common electrode, and a signal detecting electrode is provided,
and the control device supplies power between the feeding electrode
and the common electrode according to a preset control signal and
detects a force detection signal from the signal detecting
electrode.
[0047] With this constitution, it is possible to perform function
switching control in which the second piezoelectric element joined
between the common electrode and the signal detecting electrode and
made to perform a force detecting function is made to function as
an actuator according to circumstances.
[0048] According to the first input-output device in accordance
with an embodiment of the present invention, the first
piezoelectric composite device according to an embodiment of the
present invention is applied. Therefore a part of the piezoelectric
composite device functioning as a piezoelectric bimorph type
actuator can be used as a force detecting sensor. Thus, the
function of the actuator and the function of the force detecting
sensor can be used at the same time. In addition, as compared with
a case where the actuator and the force detecting sensor are
provided separately from each other, a mounting space is shared and
thus the input-output device can be made more compact.
[0049] According to the first electronic device in accordance with
an embodiment of the present invention, the first input-output
device according to an embodiment of the present invention is
applied. Therefore a part of the piezoelectric composite device
functioning as a piezoelectric bimorph type actuator can be used as
a force detecting sensor. Thus, the function of the actuator and
the function of the force detecting sensor can be used at the same
time. In addition, as compared with a case where the actuator and
the force detecting sensor are provided separately from each other,
a mounting space is shared and thus the electronic device can be
made more compact.
[0050] The second piezoelectric composite device according to an
embodiment of the present invention includes: a first laminate and
a second laminate formed by laminating a lead electrode and one or
more piezoelectric elements; and a third laminate having another
lead electrode, and having one or more piezoelectric elements
laminated between the first laminate and the second laminate.
[0051] With this constitution, when power is supplied to the lead
electrodes of the first laminate and the second laminate, the one
or more piezoelectric elements can be vibrated, so that the
piezoelectric composite device can be made to function as a
piezoelectric bimorph type actuator. In addition, when a force is
applied to the third laminate, a force detection signal can be
output from the lead electrode of the third laminate, so that the
piezoelectric composite device can be made to function as a force
detecting sensor. Further, a composite function combining the
above-described functions can be realized. It is thereby possible
to provide a multifunction actuator of a low voltage driving type
or the like that enables both the functions to be used
simultaneously.
[0052] The second method of manufacturing a piezoelectric composite
device according to an embodiment of the present invention
includes: forming a laminate by one or more lead electrodes and
piezoelectric elements; then electrically dividing the laminate to
demarcate at least three laminates; drawing out electrodes from a
piezoelectric element situated in a central laminate of the
demarcated laminates; and further drawing out electrodes from
piezoelectric elements of the other laminates situated on both
sides of the central laminate.
[0053] With this constitution, a piezoelectric bimorph type
actuator and a force detecting sensor can be formed within an
identical structure. It is thereby possible to manufacture a
multifunction actuator of a low voltage driving type or the like
that enables both the function of the actuator and the function of
the force detecting sensor to be used simultaneously. In addition,
as compared with a case where the actuator and the force detecting
sensor are provided separately from each other, a mounting space is
shared and thus the electronic device can be made more compact.
[0054] In the second method of controlling a piezoelectric
composite device according to an embodiment of the present
invention, a control device connected to the lead electrode of each
of a first laminate, a second laminate, and a third laminate formed
by laminating a lead electrode and one or more piezoelectric
elements is provided, and the control device supplies power to the
lead electrode of each of the first laminate and the second
laminate according to a preset control signal, and supplies power
to the lead electrode of the third laminate or detects a force
detection signal from the lead electrode of the third laminate.
[0055] With this constitution, it is possible to perform function
switching control in which the piezoelectric element or the
piezoelectric elements of the third laminate made to perform a
force detecting function is or are made to function as an actuator
according to circumstances.
[0056] According to the second input-output device in accordance
with an embodiment of the present invention, the second
piezoelectric composite device according to an embodiment of the
present invention is applied. Therefore a part of the piezoelectric
composite device functioning as a piezoelectric bimorph type
actuator can be used as a force detecting sensor. Thus, the
function of the actuator and the function of the force detecting
sensor can be used at the same time. In addition, as compared with
a case where the actuator and the force detecting sensor are
provided separately from each other, a mounting space is shared and
thus the input-output device can be made more compact.
[0057] According to the second electronic device in accordance with
an embodiment of the present invention, the second input-output
device according to an embodiment of the present invention is
applied. Therefore a part of the piezoelectric composite device
functioning as a piezoelectric bimorph type actuator can be used as
a force detecting sensor. Thus, the function of the actuator and
the function of the force detecting sensor can be used at the same
time. In addition, as compared with a case where the actuator and
the force detecting sensor are provided separately from each other,
a mounting space is shared and thus the electronic device can be
made more compact.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] FIGS. 1A and 1B are a perspective view and a sectional view
of an example of structure of a multifunction piezoelectric
actuator 1 according to a first embodiment of the present
invention;
[0059] FIG. 2 is a block diagram showing an example of feedback
control of the multifunction piezoelectric actuator 1;
[0060] FIGS. 3A, 3B, and 3C are process diagrams representing an
example (1) of manufacturing of the multifunction piezoelectric
actuator 1;
[0061] FIGS. 4A and 4B are process diagrams representing an example
(2) of manufacturing of the multifunction piezoelectric actuator
1;
[0062] FIGS. 5A and 5B are diagrams showing an example of structure
of a multifunction piezoelectric actuator (fixed connection type)
10 according to a second embodiment;
[0063] FIG. 6 is a diagram showing an example of sectional
structure of a multifunction piezoelectric actuator 100 of a
variable connection type according to a third embodiment and an
example of internal connection of the multifunction piezoelectric
actuator 100;
[0064] FIGS. 7A and 7B are block diagrams showing examples of
configuration of a control system for the multifunction
piezoelectric actuator 100;
[0065] FIG. 8 is a block diagram showing an example of feedback
control of the multifunction piezoelectric actuator 100;
[0066] FIGS. 9A, 9B, and 9C are process diagrams representing an
example (1) of manufacturing of the multifunction piezoelectric
actuator 100;
[0067] FIGS. 10A, 10B, and 10C are process diagrams representing an
example (2) of manufacturing of the multifunction piezoelectric
actuator 100;
[0068] FIGS. 11A, 11B, 11C, and 11D are top views showing an
example of electrode patterns, the top views being supplementary to
the process diagrams;
[0069] FIG. 12 is a sectional view showing an example of lamination
of a film-shaped piezoelectric substance 100', the sectional view
being supplementary to the process diagrams;
[0070] FIGS. 13A, 13B, and 13C are process diagrams representing an
example (3) of manufacturing of the multifunction piezoelectric
actuator;
[0071] FIGS. 14A, 14B, and 14C are process diagrams representing an
example (4) of manufacturing of the multifunction piezoelectric
actuator;
[0072] FIGS. 15A and 15B are process diagrams representing an
example (5) of manufacturing of the multifunction piezoelectric
actuator;
[0073] FIGS. 16A, 16B, 16C, 16D, 16E, 16F, and 16G are diagrams
showing an example of seven kinds of manufactured electrode
patterns P1 to P7;
[0074] FIGS. 17A and 17B are diagrams of an example of lamination
of another film-shaped piezoelectric substance and an example of
manufacturing of a through hole part of the film-shaped
piezoelectric substance;
[0075] FIGS. 18A and 18B are perspective views of an example of
structure of a portable terminal device 200' to which a first
input-output device 60' according to a fourth embodiment is
applied;
[0076] FIG. 19 is a circuit diagram showing an example of
configuration of a control system of the input-output device
60';
[0077] FIG. 20 is a perspective view of an example of structure of
a portable terminal device 200 to which a second input-output
device 60 according to a fifth embodiment is applied;
[0078] FIG. 21 is a sectional view of an example of structure of
the input-output device 60 including a touch panel 61, display
section 62, and multifunction piezoelectric actuators 100a and
100b;
[0079] FIGS. 22A and 22B are sectional views of an example of
operation when the touch panel in the input-output device 60 is
pressed;
[0080] FIG. 23 is a block diagram showing an example of
configuration of main parts of the portable terminal device
200;
[0081] FIG. 24 is a diagram representing an example of operation of
the portable terminal device 200;
[0082] FIGS. 25A, 25B, and 25C are diagrams representing an example
of a series of operations and an example of waveforms in the
input-output device 60;
[0083] FIG. 26 is a perspective view of an example of structure of
a multilayer piezoelectric bimorph type actuator 300 according to a
conventional example; and
[0084] FIG. 27 is a sectional view showing an example of a
laminated structure of the multilayer piezoelectric bimorph type
actuator 300.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0085] A piezoelectric composite device, a method of manufacturing
the same, a method of handling the same, a method of controlling
the same, an input-output device, and an electronic device
according to embodiments of the present invention will hereinafter
be described with reference to the drawings.
[0086] FIGS. 1A and 1B are a perspective view and a sectional view
of an example of structure of a multifunction piezoelectric
actuator 1 according to a first embodiment of the present
invention.
[0087] The first embodiment includes: a first piezoelectric element
joined between a feeding electrode and a common electrode; and a
second piezoelectric element joined between the common electrode
and a signal detecting electrode; wherein a predetermined voltage
is supplied between the feeding electrode and the common electrode,
and a force detection signal based on an external force is
extracted from the detecting electrode. Thus a piezoelectric
composite device can be provided which combines a piezoelectric
bimorph type actuator vibrating on the basis of the predetermined
voltage supplied between the feeding electrode and the common
electrode, and a force detecting sensor outputting the force
detection signal based on the external force.
[0088] The multifunction piezoelectric actuator 1 of a fixed
connection type shown in FIG. 1A is an example of a piezoelectric
composite device, and has the function of a piezoelectric actuator
and the function of a force detecting sensor. As shown in FIG. 1B,
the multifunction piezoelectric actuator 1 is formed by at least
dividing (separating) one laminate electrically into two
single-layer piezoelectric substances 4a and 4b. The multifunction
piezoelectric actuator 1 has an electrode for feeding (hereinafter
referred to as a feeding electrode) 2, a common electrode 6, and an
electrode for signal detection (hereinafter referred to as a
detecting electrode) 8. A first piezoelectric element 3 is joined
between the feeding electrode 2 and the common electrode 6 to form
one single-layer piezoelectric substance 4a. A predetermined
voltage Va is supplied between the feeding electrode 2 and the
common electrode 6 in the single-layer piezoelectric substance 4a
so that the single-layer piezoelectric substance 4a functions as a
piezoelectric actuator.
[0089] A second piezoelectric element 7 is joined between the
common electrode 6 and the detecting electrode 8 to form another
single-layer piezoelectric substance 4b. A force detection signal
(hereinafter referred to also as a force detection voltage Vd)
based on an external force is extracted from the detecting
electrode 8. Thus the single-layer piezoelectric substance 4b
functions as a force detecting sensor. The multifunction
piezoelectric actuator 1 has three terminals 9a, 9b, and 9c. The
first terminal 9a is connected to the feeding electrode 2. The
terminal 9a is connected with a lead L1. The second terminal 9b is
connected to the common electrode 6. The terminal 9b is connected
with a lead L2. The third terminal 9c is connected to the detecting
electrode 8. The terminal 9c is connected with a lead L3.
[0090] When the multifunction piezoelectric actuator 1 is formed as
described above, actuator control section is connected to the lead
L1 and the lead L2, and power is supplied to the first
piezoelectric element 3 via the terminal 9a and the terminal 9b,
the first piezoelectric element 3 vibrates. When an external force
is applied to the second piezoelectric element 7, a detection
voltage Vd is output to the lead L3. Thus, when only the force
detection signal (detection voltage Vd) based on the external force
modulated by the predetermined voltage Va supplied between the
feeding electrode 2 and the common electrode 6 can be extracted, it
is possible to provide for example a multifunction actuator of a
low voltage driving type that enables both the functions to be used
simultaneously.
[0091] FIG. 2 is a block diagram showing an example of feedback
control of the multifunction piezoelectric actuator 1.
[0092] In this example, a control device 50 connected to each of
the feeding electrode 2, the common electrode 6, and the detecting
electrode 8 is provided. The control device 50 operates to supply
power between the feeding electrode 2 and the common electrode 6
according to a preset control target value (y0, F0) and detect a
force detection signal from the detecting electrode 8 (first
control method).
[0093] The control device 50 shown in FIG. 2 has actuator control
section 15, a detection operation unit 17', and a comparator 19.
The control device 50 performs feedback control (servo control;
closed loop actuator control) of the multifunction piezoelectric
actuator 1 on the basis of the control target value (y0, F0)
constituting one example of a control signal. The control target
value y0 represents a displacement. The control target value F0
represents a force. The letter y denotes displacement by operation
of the multifunction piezoelectric actuator 1. F denotes force
generated by operation of the actuator. Generally, when the
positioning of an object is controlled, the displacement y is
selected as a controlled quantity, and when the force F exerted by
the actuator on another object or the like is controlled, the force
F is selected as a controlled quantity.
[0094] The actuator control section 15 in this example is connected
with the feeding electrode 2 via the lead L1 shown in FIG. 1A. The
actuator control section 15 determines a command voltage on the
basis of the control target value y0 or F0 given to the actuator
control section 15 in advance, and applies the command voltage to
the single-layer piezoelectric substance 4a functioning as the
actuator in the multifunction piezoelectric actuator 1.
[0095] A connection between the above-described detecting electrode
8 and the detection operation unit 17' is made by the lead L3 shown
in FIG. 1A. The detection operation unit 17' is an example of
detector. The detection operation unit 17' detects a pressing force
F', and converts a detection voltage Vd output from the detecting
electrode 8 into two control quantities. The detection operation
unit 17' is provided in advance with functions y=f(v) and F=g(v) or
a conversion table defining a relation between the detection
voltage Vd (=v) and the displacement y or between the detection
voltage Vd (=v) and the force F.
[0096] The conversion table stores for example the displacement
y=0.2, 0.4, 0.6, 0.8 . . . [mm] and the force F=3, 6, 9, 12 . . .
[gf] for voltage v=1, 2, 3, 4 . . . . Let y1 or F1 be a control
quantity after conversion. The comparator 19 is connected to the
detection operation unit 17' to compare the control quantity y1 or
F1 after conversion with the control target value (y0, F0). A
result of the comparison is output to the actuator control section
15 to determine a new command voltage.
[0097] The detection voltage Vd occurring in the piezoelectric
element 7 functioning as force detecting sensor as a result of the
pressing force F' being applied to the actuator 1 in operation is
output to the detection operation unit 17'. The detection voltage
Vd is converted into a necessary control quantity y1 or F1 by the
detection operation unit 17', and then compared with the target
value (y0, F0) at the comparator 19. On the basis of a result of
the comparison, the actuator control section 15 determines a new
command voltage. The new command voltage is applied to the
piezoelectric element 3 functioning as actuator in the
multifunction piezoelectric actuator 1.
[0098] While the single-layer piezoelectric substance 4a and the
single-layer piezoelectric substance 4b in the multifunction
piezoelectric actuator 1 according to the first embodiment of the
present invention are mechanically within an identical structure
and close to each other, the single-layer piezoelectric substance
4a and the single-layer piezoelectric substance 4b are electrically
independent of each other with the common electrode 6 as a boundary
between the single-layer piezoelectric substance 4a and the
single-layer piezoelectric substance 4b. In this respect, a part of
the multifunction piezoelectric actuator 1 functioning as a
piezoelectric bimorph type actuator can be used as a force
detecting sensor. Therefore the function of the actuator and the
function of the force detecting sensor can be used at the same
time. In addition, as compared with a case where the actuator and
the force detecting sensor are provided separately from each other,
a mounting space is shared and thus an electronic device can be
made more compact.
[0099] FIGS. 3A, 3B, and 3C and FIGS. 4A and 4B are process
diagrams representing an example (1 and 2) of formation of the
multifunction piezoelectric actuator 1.
[0100] In the first embodiment, a film-shaped piezoelectric
substance 1' to be used as the piezoelectric element 3 and the
piezoelectric element 7 shown in FIGS. 1A and 1B is formed.
Thereafter an electrode pattern 2a to form the feeding electrode 2
and the detecting electrode 8 is formed on one surface of the
film-shaped piezoelectric substance 1'. Further, the film-shaped
piezoelectric substance 1' provided with the electrode pattern 2a
is cut into a desired size. Then, the film-shaped piezoelectric
substance 1' provided with the electrode pattern cut into the
desired size is joined to a front side and a back side of a
conductive member 6a for the common electrode. Thereafter the leads
L1 to L3 are connected to the feeding electrode 2, the common
electrode 6, and the detecting electrode 8. Such a case will be
taken as an example.
[0101] With these manufacturing conditions, in FIG. 3A, a
film-shaped piezoelectric substance 1' to be used as the
piezoelectric element 3 and the piezoelectric element 7 is formed
first. For example, piezoelectric substance material such as a
ceramic in a powder form or the like, a solvent, a binder, a
dispersing agent and the like are mixed with each other at a
predetermined mixing ratio to form a mixed slurry not shown in the
figure. As the solvent, acetone, toluene, ethanol, MEK or the like
is used. As the binder, polyvinyl, alcohol, polyethylene or the
like is used. About 10 w % of the binder is used.
[0102] Next, the mixed slurry is made to flow out into a uniform
thickness. The film thickness is about 30 .mu.m to 50 .mu.m, for
example. Thereafter, the solvent is evaporated and dried, whereby a
film-shaped piezoelectric substance (green sheet) 1' is formed.
Since the film-shaped piezoelectric substance 1' has a small
thickness of about 30 .mu.m, the film-shaped piezoelectric
substance 1' is backed with a polymer film until a lamination
process. A drying room is maintained at normal temperature or room
temperature of 50 to 80.degree. C., and the mixed slurry made to
flow out into the uniform thickness is allowed to stand for a few
ten minutes to be dried. The mixed slurry from which the solvent is
removed forms the film-shaped piezoelectric substance 1'.
[0103] Then, as shown in FIG. 3B, an electrode pattern 2a is formed
on one surface of the film-shaped piezoelectric substance 1'.
Before this process, a process of making through holes is included.
The electrode pattern 2a is for example formed by printing an
electrode material at a predetermined position of the film-shaped
piezoelectric substance 1'. The electrode printing is performed by
screen printing. As the electrode material, an Ag--Pd alloy paste
is used. The electrode pattern 2a forms the feeding electrode 2 and
the detecting electrode 8 or the like in a subsequent process.
[0104] Next, in FIG. 3C, the film-shaped piezoelectric substance 1'
previously printed with the electrode material is cut into a
desired size. For example, a cutting device not shown in the figure
is used to cut the film-shaped piezoelectric substance 1' into
strips. This is to obtain the piezoelectric element 3 with the
feeding electrode and the piezoelectric element 7 with the
detecting electrode and the like. Then, in FIG. 3C, the film-shaped
piezoelectric substance 1' in the form of a single layer forming
the piezoelectric element 3 with the feeding electrode and the
film-shaped piezoelectric substance 1' in the form of a single
layer forming the piezoelectric element 7 with the detecting
electrode are dried to remove the binder. As drying conditions in
this case, the temperature is maintained at normal temperature or
room temperature of about 400.degree. C. to 500.degree. C., and the
film-shaped piezoelectric substance 1' is allowed to stand for a
few ten minutes for degreasing. In practice, the temperature is
increased to about 400.degree. C. to 500.degree. C. over a few days
while a rate of the temperature increase is controlled in a
furnace.
[0105] The film-shaped piezoelectric substance 1' in the form of a
single layer from which the binder has previously been removed is
fired. As firing conditions in this case, a firing temperature is
about 10.degree. C. to 1200.degree. C., and a firing time is about
60 minutes. At this time, a degreasing process is similarly
performed, and the temperature is increased to about 10.degree. C.
to 1200.degree. C. over a few days while a rate of the temperature
increase is controlled in a firing furnace.
[0106] Next, a conductive member 6a for the common electrode is
prepared which has a size adapted to that of the film-shaped
piezoelectric substance 1' in the form of a single layer forming
the piezoelectric element 3 with the feeding electrode and the
film-shaped piezoelectric substance 1' in the form of a single
layer forming the piezoelectric element 7 with the detecting
electrode. The conductive member 6a is cut into a size larger than
that of the feeding electrode 2 and the detecting electrode 8, for
example. This is to secure a soldering part at one end of the
conductive member 6a to form the common electrode 6.
[0107] Then, the film-shaped piezoelectric substance 1' provided
with the feeding electrode is bonded to a surface of the conductive
member 6a for the common electrode shown in FIG. 4A. At this time,
the polymer film for backing is removed, and then the piezoelectric
element 3 is bonded to one surface of the common electrode 6. The
feeding electrode 2 is faced upward. The film-shaped piezoelectric
substance 1' provided with the detecting electrode is bonded to a
back surface of the conductive member 6a. The piezoelectric element
7 is bonded to the other surface of the common electrode 6. The
piezoelectric element 7 is bonded in an opposite direction to that
of the piezoelectric element 3, that is, bonded such that the
detecting electrode 8 is faced downward. Thus, the piezoelectric
element 3 can be joined between the feeding electrode 2 and the
common electrode 6. Also, the piezoelectric element 7 can be joined
between the common electrode 6 and the detecting electrode 8.
Incidentally, as a bonding material, an epoxy resin or a UV bonding
agent is used.
[0108] Thereafter, in FIG. 4B, leads L1 to L3 necessary for the
multifunction piezoelectric actuator 1 to function as a
piezoelectric actuator and a force detecting sensor are soldered to
the feeding electrode 2, the common electrode 6, and the detecting
electrode 8, respectively. The upper surface of the piezoelectric
element 3 is covered with the feeding electrode 2, and the lead L1
is soldered to the terminal 9a of the feeding electrode 2. The lead
L1 is used to supply a predetermined voltage between the feeding
electrode 2 and the common electrode 6.
[0109] The lead L2 is soldered to the terminal 9b of the common
electrode 6. The lead L2 is used in a grounded state (GND). The
lower surface of the piezoelectric element 7 is covered with the
detecting electrode 8, and the lead L3 is soldered to the terminal
9c of the detecting electrode 8. The lead L3 is used to detect a
force detection signal (detection voltage Vd) between the detecting
electrode 8 and the common electrode 6. Thus, the multifunction
piezoelectric actuator 1 shown in FIGS. 1A and 1B and the like is
completed. Thereafter a process of polarizing the piezoelectric
elements is performed as required. The polarizing process refers to
a process of aligning the molecular magnet of the piezoelectric
elements in a certain direction by applying an external
magnetization.
[0110] Thus the multifunction piezoelectric actuator 1 can be
manufactured which combines the piezoelectric bimorph type actuator
vibrating according to the predetermined voltage Va supplied
between the feeding electrode 2 and the common electrode 6 with the
force detecting sensor outputting the force detection signal based
on the pressing force F'.
[0111] Thus, according to the multifunction piezoelectric actuator
according to the first embodiment, a method of controlling the
multifunction piezoelectric actuator, and a method of manufacturing
the multifunction piezoelectric actuator, the piezoelectric element
3 is joined between the feeding electrode 2 and the common
electrode 6, and the piezoelectric element 7 is joined between the
common electrode 6 and the detecting electrode 8. With this
laminated structure as a precondition, the control device 50
supplies the predetermined voltage Va between the feeding electrode
2 and the common electrode 6, and extracts the detection voltage Vd
based on the external force (pressing force F') from the detecting
electrode 8.
[0112] Thus, the single-layer piezoelectric substance 4a formed by
the piezoelectric element 3 joined between the feeding electrode 2
and the common electrode 6 can perform an actuator function, and
the single-layer piezoelectric substance 4b formed by the
piezoelectric element 7 joined between the common electrode 6 and
the detecting electrode 8 can perform a force detecting
function.
[0113] With this structure, it is possible to provide the
multifunction piezoelectric actuator 1 which combines the
piezoelectric bimorph type actuator vibrating according to the
predetermined voltage Va including an alternating current with a
frequency of 50 Hz to 500 Hz with the force detecting sensor
detecting the pressing force F'. In addition, since the actuator
and the force detecting sensor are formed within an identical
structure, as compared with a case where the actuator and the force
detecting sensor are provided separately from each other, a
mounting space is shared and thus an electronic device can be made
more compact.
[0114] FIGS. 5A and 5B are diagrams showing an example of structure
of a multifunction piezoelectric actuator (fixed connection type)
10 according to a second embodiment. FIG. 5A is a perspective view
of the structure example. FIG. 5B is a sectional view taken along a
line X1-X2 of FIG. 5A.
[0115] The second embodiment relates to an actuator in which
piezoelectric elements having different amounts of distortion in
two or more layers, or piezoelectric elements and a
non-piezoelectric element are bonded to each other, and a bend
deformation of the bonded object which deformation is caused by a
difference in the amounts of distortion of both the elements when a
voltage is applied to the piezoelectric elements is used
dynamically. The second embodiment includes two laminates formed by
laminating one or more piezoelectric elements, and another laminate
formed by lamination between these laminates and having one or more
piezoelectric elements. The one or more piezoelectric elements can
be vibrated by supplying power to lead electrodes of the former two
laminates, and when a force is applied to the latter laminate, a
force detection signal can be output from a lead electrode of the
laminate.
[0116] The multifunction piezoelectric actuator 10 shown in FIG. 5A
is an example of a piezoelectric composite device, and has the
function of a piezoelectric actuator and the function of a force
detecting sensor. As shown in FIG. 5B, the multifunction
piezoelectric actuator 10 is formed by at least dividing
(separating) one laminate 14 electrically into three laminated
piezoelectric substance groups 14a, 14b, and 14c.
[0117] A central electrode 13 drawn out from a piezoelectric
element situated at a center of the laminated piezoelectric
substance group 14c in this example is used for force detection,
and electrodes drawn out from piezoelectric elements of the other
laminated piezoelectric substance groups 14a and 14b situated on
both sides of the laminated piezoelectric substance group 14c are
used for power supply. In this example, of one or more laminated
piezoelectric substance groups 14a, 14b, and 14c divided
electrically, the laminated piezoelectric substance group 14c
including a neutral surface at the time of bend deformation is used
for force detection, and the laminated piezoelectric substance
groups 14a and 14b situated at a distance from the neutral surface
are used for an actuator.
[0118] The central electrode 13 drawn out from the piezoelectric
element situated at the center of the laminated piezoelectric
substance group 14c in this example is used for a force detecting
sensor, and the electrodes drawn out from the piezoelectric
elements of the other laminated piezoelectric substance groups 14a
and 14b situated on both sides of the laminated piezoelectric
substance group 14c are used to supply power to the actuator. In
this example, of one or more laminated piezoelectric substance
groups 14a, 14b, and 14c divided electrically, the laminated
piezoelectric substance group 14c including the neutral surface at
the time of bend deformation is used as the force detecting sensor,
and the laminated piezoelectric substance groups 14a and 14b
situated at a distance from the neutral surface are used as the
actuator.
[0119] The first laminated piezoelectric substance group 14a is an
example of a first laminate, and is formed by laminating a lead
electrode (hereinafter referred to as an upper part surface
electrode 11) and one or more piezoelectric elements. Each
piezoelectric element includes an electrode and a piezoelectric
substance. The second laminated piezoelectric substance group 14b
is an example of a second laminate, and is formed by laminating a
lead electrode (hereinafter referred to as a lower part surface
electrode 12) and one or more piezoelectric elements. Each
piezoelectric element includes an electrode and a piezoelectric
substance. The upper part surface electrode 11 and the lower part
surface electrode 12 are connected to each other within the
laminate. Other electrodes are also connected to each other within
the laminate.
[0120] The third laminated piezoelectric substance group 14c is an
example of a third laminate. The third laminated piezoelectric
substance group 14c is laminated between the laminated
piezoelectric substance group 14a and the laminated piezoelectric
substance group 14b, and has one or more piezoelectric elements.
The laminated piezoelectric substance group 14c has the central
electrode 13 as an example of another lead electrode. The central
electrode 13 is situated at the neutral surface of bend deformation
of the laminated piezoelectric substance group 14a, the laminated
piezoelectric substance group 14b, and the laminated piezoelectric
substance group 14c.
[0121] The multifunction piezoelectric actuator 10 of a fixed
connection type has four terminals 16a to 16d. The first terminal
16a is connected to the upper part surface electrode 11. The
terminal 16a is connected with a lead L1. The second terminal 16b
is connected to the lead electrode of the laminated piezoelectric
substance group 14b. The terminal 16b is connected with a lead L2.
The third terminal 16c is connected to the lead electrode of the
laminated piezoelectric substance group 14c. The terminal 16c is
connected with a lead L3. The fourth terminal 16d is connected to
the lead electrode of the laminated piezoelectric substance group
14c. The terminal 16d is connected with a lead L4.
[0122] The multifunction piezoelectric actuator 10 of the fixed
connection type is formed as described above. When actuator control
section is connected to the lead L1 and the lead L2 and power is
supplied to the piezoelectric elements of the laminated
piezoelectric substance group 14a and the laminated piezoelectric
substance group 14b via the terminal 16a and the terminal 16b, the
laminated piezoelectric substance group 14a and the laminated
piezoelectric substance group 14b vibrate. When an external force
is applied to the piezoelectric elements of the laminated
piezoelectric substance group 14c, a detection voltage Vd is output
to the lead L3 and the lead L4.
[0123] Thus, according to the multifunction piezoelectric actuator
according to the second embodiment and a method of handing the
multifunction piezoelectric actuator, a laminate formed by
laminating one or more piezoelectric elements is electrically
divided into one or more laminated piezoelectric substance groups,
and of the one or more laminated piezoelectric substance groups
divided electrically, the laminated piezoelectric substance group
14c is made to function as a force detecting sensor for detecting
an external force applied to the piezoelectric elements.
[0124] Hence, since a part of the multifunction piezoelectric
actuator 10 functioning as a piezoelectric bimorph type actuator
can be used as a force detecting sensor, the function of the
actuator and the function of the force detecting sensor can be used
at the same time. A composite function obtained by combining such
functions can be realized. It is thus possible to provide for
example the multifunction actuator 10 of a low voltage driving type
that enables both the functions to be used simultaneously. In
addition, since the actuator and the force detecting sensor are
formed within an identical structure, as compared with a case where
the actuator and the force detecting sensor are provided separately
from each other, a mounting space is shared and thus an electronic
device can be made more compact.
[0125] FIG. 6 is a diagram showing an example of sectional
structure of a multifunction piezoelectric actuator 100 of a
variable connection type according to a third embodiment and an
example of internal connection of the multifunction piezoelectric
actuator 100.
[0126] The multifunction piezoelectric actuator 100 of the variable
connection type according to the third embodiment has seven leads
L1 to L7, which are more than those of the fixed connection type by
three. The multifunction piezoelectric actuator 100 shown in FIG. 6
makes the whole of a laminate function only as a piezoelectric
actuator and makes the whole of the laminate function as a
piezoelectric actuator and a force detecting sensor
simultaneously.
[0127] The multifunction piezoelectric actuator 100 has a
piezoelectric substance laminated between electrodes. The
multifunction piezoelectric actuator 100 is formed by at least
electrically dividing a laminate having a total of 18 layers of
piezoelectric substance #1 to #18, an upper part surface electrode
11, a lower part surface electrode 12, a central electrode 13, and
16 layers of electrodes IE1 to IE16 into three laminated
piezoelectric substance groups 14a, 14b, and 14c. Also in this
case, as in the fixed connection type, the laminated piezoelectric
substance group 14c is sandwiched between the laminated
piezoelectric substance group 14a and the laminated piezoelectric
substance group 14b.
[0128] The laminated piezoelectric substance group 14a includes the
upper part surface electrode 11, the electrodes IE1 to IE5, and the
five layers of piezoelectric substance #1 to #5. The laminated
piezoelectric substance group 14a functions as a piezoelectric
actuator. The piezoelectric substance #1 is laminated between the
upper part surface electrode 11 and the electrode IE1. The
piezoelectric substance #2 is laminated between the electrode IE1
and the electrode IE2. The piezoelectric substance #3 is laminated
between the electrode IE2 and the electrode IE3. The piezoelectric
substance #4 is laminated between the electrode IE3 and the
electrode IE4. The piezoelectric substance #5 is laminated between
the electrode IE4 and the lead electrode IE5.
[0129] The laminated piezoelectric substance group 14c is laminated
between the laminated piezoelectric substance group 14a and the
laminated piezoelectric substance group 14b. The laminated
piezoelectric substance group 14c includes the central electrode
13, the electrodes IE6 to IE8, four layers of piezoelectric
substance, the electrodes IE9 to IE11, and four layers of
piezoelectric substance. The laminated piezoelectric substance
group 14c functions as a force detecting sensor. The piezoelectric
substance #6 is laminated between the electrode IE5 and the
electrode IE6. The piezoelectric substance #7 is laminated between
the electrode IE6 and the electrode IE7. The piezoelectric
substance #8 is laminated between the electrode IE7 and the
electrode IE8. The piezoelectric substance #9 is laminated between
the electrode IE8 and the central electrode 13.
[0130] The piezoelectric substance #10 is laminated between the
central electrode 13 and the electrode IE9. The piezoelectric
substance #11 is laminated between the electrode IE9 and the
electrode IE10. The piezoelectric substance #12 is laminated
between the electrode IE10 and the electrode IE11. The central
electrode 13 is situated at a neutral surface of bend deformation
of the laminated piezoelectric substance group 14a, the laminated
piezoelectric substance group 14b, and the laminated piezoelectric
substance group 14c.
[0131] The laminated piezoelectric substance group 14b includes the
lower part surface electrode 12, the electrodes IE12 to IE16, and
five layers of piezoelectric substance. The laminated piezoelectric
substance group 14b functions as a piezoelectric actuator. The
piezoelectric substance #13 is laminated between the electrode IE11
and the electrode IE12. The piezoelectric substance #14 is
laminated between the electrode IE12 and the electrode IE13. The
piezoelectric substance #15 is laminated between the electrode IE13
and the electrode IE14. The piezoelectric substance #16 is
laminated between the electrode IE14 and the electrode IE15. The
piezoelectric substance #17 is laminated between the electrode IE15
and the electrode IE16. The piezoelectric substance #18 is
laminated between the electrode IE16 and the lower part surface
electrode 12.
[0132] The upper part surface electrode 11, the electrode IE2, and
the electrode IE4 in the laminated piezoelectric substance group
14a in FIG. 6 are connected to each other within the laminate. The
upper part surface electrode 11 is connected to the lead L1 via a
first terminal 16a. The electrode IE1 and the electrode IE3 are
connected to the lead electrode IE5 within the laminate. The lead
electrode IE5 is connected to the lead L2 via a second terminal
16b.
[0133] The electrode IE8 of the laminated piezoelectric substance
group 14c is connected to the lead electrode IE6 within the
laminate. The lead electrode IE6 is connected to the lead L3 via a
terminal 16c. The electrode IE7 and the electrode IE10 are
connected to the central electrode 13. The central electrode 13 is
connected to the lead L4 via a terminal 16d. The electrode IE9 is
connected to the lead electrode IE11 within the laminate. The lead
electrode IE11 is connected to the lead L5 via a terminal 16e.
[0134] The electrode IE14 and the electrode IE16 of the laminated
piezoelectric substance group 14b are connected to the lead
electrode IE12 within the laminate. The lead electrode IE12 is
connected to the lead L6 via a terminal 16f. The electrode IE13 and
the electrode IE15 are connected to the lower part surface
electrode 12 within the laminate. The lower part surface electrode
12 is connected to the lead L7 via a terminal 16g.
[0135] Incidentally, in FIG. 6, the piezoelectric substances #8 to
#12 shown at positions near the central electrode 13 function as
the force detecting sensor. The piezoelectric substances #1 to #5
and the piezoelectric substances #14 to #18 outlined over and under
the piezoelectric substances #8 to #12 form a part functioning as
the actuator 100. The piezoelectric substances #6 and #13 are
positioned at a boundary between the actuator and the force
detecting sensor, and function as a cushioning material.
[0136] FIGS. 7A and 7B are block diagrams showing examples of
configuration of a control system for the multifunction
piezoelectric actuator 100.
[0137] In this example, a control device 50 is provided which is
connected to the upper part surface electrode 11, the electrode
IE5, the electrode IE6, the central electrode 13, the electrode
IE11, the electrode IE12, and the lower part surface electrode 12
of the laminated piezoelectric substance groups 14a to 14c.
According to a preset control signal, the control device 50
supplies power to the upper part surface electrode 11, the
electrode IE5, the electrode IE12, and the lower part surface
electrode 12 of the laminated piezoelectric substance groups 14a
and 14b, and the control device 50 supplies power to the electrode
IE6, the central electrode 13, and the electrode IE11 of the
laminated piezoelectric substance group 14c or the control device
50 detects a force detection signal Sout from the electrode IE6,
the central electrode 13, and the electrode IE11.
[0138] The control device 50 shown in FIG. 7A has actuator control
section 15, detecting section 17, and a connecting circuit 18. In
this case, the control device 50 makes the multifunction
piezoelectric actuator 100 function as the piezoelectric actuator
and the force detecting sensor simultaneously. The connecting
circuit 18 is formed by a gate array using a MOSFET switch circuit,
for example. The actuator control section 15 is connected to a
higher-level control system. The actuator control section 15 is for
example supplied with vibration waveform pattern data D1 and a
function selecting signal S1 as an example of a control signal from
the higher-level control system. The actuator control section 15
drives and controls the multifunction piezoelectric actuator 100 on
the basis of the vibration waveform pattern data D1 and the
function selecting signal S1.
[0139] When the function selecting signal S1 is to make the
multifunction piezoelectric actuator 100 function as the
piezoelectric actuator and the force detecting sensor
simultaneously, for example, the actuator control section 15
outputs a switch connecting signal SS1 to the connecting circuit 18
to connect the lead L1 with the lead L7. Also, the lead L2 and the
lead L6 are connected to each other, and connected to the actuator
control section 15. Thereby an actuator circuit including the
piezoelectric substances #1 to #5 and the piezoelectric substances
#14 to #18 of the laminated piezoelectric substance group 14a and
the laminated piezoelectric substance group 14b can be constructed
via the terminals 16a, 16b, 16f, and 16g shown in FIG. 6.
[0140] Further, on the basis of the switch connecting signal SS1,
the actuator control section 15 connects the lead L3 and the lead
L5 to each other, and connects the lead L3 and the lead L5 and the
lead L4 to the detecting section 17. Thereby a force detecting
sensor circuit including the central electrode 13 and the
piezoelectric substances #7 to #12 of the laminated piezoelectric
substance group 14c can be constructed via the terminals 16c, 16d,
and 16e shown in FIG. 6.
[0141] With such an actuator circuit and such a force detecting
sensor circuit constructed, the actuator control section 15
generates an actuator driving voltage Va based on the vibration
waveform pattern data D1. When the actuator driving voltage Va is
supplied through the leads L1, L2, L6, and L7 to the piezoelectric
substances #1 to #5 and the piezoelectric substances #14 to #18 of
the laminated piezoelectric substance group 14a and the laminated
piezoelectric substance group 14b via the terminals 16a, 16b, 16f,
and 16g shown in FIG. 6, the laminated piezoelectric substance
group 14a vibrates so as to elongate, and the laminated
piezoelectric substance group 14b vibrates so as to contract with
the central electrode 13 as a reference. Thus the multifunction
piezoelectric actuator 100 can be operated as an actuator.
[0142] When an external force is applied to the piezoelectric
substances #7 to #12 of the laminated piezoelectric substance group
14c in this state or in a state in which the actuator driving
voltage Va is not supplied, a force detection voltage Vd occurs in
the lead L3 and the lead L5. The force detection voltage Vd is
output to the detecting section 17. The detecting section 17 for
example detects the force detection voltage Vd, and outputs the
force detection voltage Vd as a force detection signal Sout to the
higher-level control system. Thus the multifunction piezoelectric
actuator 100 can also be operated as a force detecting sensor while
the actuator function of the multifunction piezoelectric actuator
100 is retained.
[0143] A control system shown in FIG. 7B makes the multifunction
piezoelectric actuator 100 function only as a piezoelectric
actuator. In this case, the actuator control section 15 is supplied
with the vibration waveform pattern data D1 and the function
selecting signal S1 from the higher-level control system. The
actuator control section 15 drives and controls the multifunction
piezoelectric actuator 100 on the basis of the vibration waveform
pattern data D1 and the function selecting signal S1.
[0144] When the function selecting signal S1 is to make the
multifunction piezoelectric actuator 100 function only as the
piezoelectric actuator, for example, the actuator control section
15 outputs a switch connecting signal SS2 to the connecting circuit
18 to connect the leads L1, L3, L5, and L7 with each other. Also,
the leads L2, L4, and L6 are connected to each other, and connected
to the actuator control section 15. Thereby an actuator circuit
including the piezoelectric substances #1 to #18 of the laminated
piezoelectric substance group 14a, the laminated piezoelectric
substance group 14c, and the laminated piezoelectric substance
group 14b can be constructed via the terminals 16a, 16b, 16c, 16d,
16e, 16f, and 16g shown in FIG. 6.
[0145] With such an actuator circuit constructed, the actuator
control section 15 generates the actuator driving voltage Va based
on the vibration waveform pattern data D1. When the actuator
driving voltage Va is supplied through the leads L1, L2, L3, L4,
L5, L6, and L7 to the piezoelectric substances #1 to #18 of the
laminated piezoelectric substance group 14a, the laminated
piezoelectric substance group 14c, and the laminated piezoelectric
substance group 14b via the terminals 16a, 16b, 16c, 16d, 16e, 16f,
and 16g shown in FIG. 6, the laminated piezoelectric substance
group 14a and an upper half of the laminated piezoelectric
substance group 14c vibrate so as to elongate, and a lower half of
the laminated piezoelectric substance group 14c and the laminated
piezoelectric substance group 14b vibrate so as to contract with
the central electrode 13 as a reference. Thus the whole of the
laminate of the multifunction piezoelectric actuator 100 can be
operated as an actuator.
[0146] Thus, according to a method of controlling the multifunction
piezoelectric actuator according to the third embodiment, the
control device 50 is connected to the upper part surface electrode
11, the electrode IE5, the electrode IE6, the central electrode 13,
the electrode IE11, the electrode IE12, and the lower part surface
electrode 12 of the laminated piezoelectric substance groups 14a,
14b, and 14c including the 18 laminated layers of piezoelectric
substance #1 to #18. The control device 50 supplies power to the
upper part surface electrode 11, the electrode IE5, the electrode
IE12, and the lower part surface electrode 12 of the laminated
piezoelectric substance groups 14a and 14b according to the preset
function selecting signal SS1 or the like, and detects a detection
voltage Vd from the electrode IE6, the central electrode 13, and
the electrode IE11 of the laminated piezoelectric substance group
14c.
[0147] As a result, an actuator function can be performed by the
laminated piezoelectric substance groups 14a and 14b, and a force
detecting function can be performed by the laminated piezoelectric
substance group 14c. In addition, when power is supplied to each of
the upper part surface electrode 11, the electrode IE5, the
electrode IE6, the central electrode 13, the electrode IE11, the
electrode IE12, and the lower part surface electrode 12 of the
laminated piezoelectric substance groups 14a, 14b, and 14c, an
actuator function can be performed by the laminated piezoelectric
substance groups 14a, 14b, and 14c. Thus, function changing
control, which for example makes the piezoelectric substance #7 to
#12 of the laminated piezoelectric substance group 14c performing
the force detecting function function as an actuator according to
circumstances, can be performed.
[0148] FIG. 8 is a block diagram showing an example of feedback
control of the multifunction piezoelectric actuator 100.
[0149] The control device 50 shown in FIG. 8 has actuator control
section 15, a detection operation unit 17', and a comparator 19.
The control device 50 performs feedback control (servo control;
closed loop actuator control) of the multifunction piezoelectric
actuator 100 on the basis of a control target value (y0, F0). The
control target value y0 represents a displacement. The control
target value F0 represents a force. The letter y denotes
displacement by operation of the multifunction piezoelectric
actuator 100. F denotes force generated by operation of the
actuator 100. Generally, when the positioning of an object is
controlled, the displacement y is selected as a controlled
quantity, and when the force F exerted by the actuator 100 on
another object or the like is controlled, the force F is selected
as a controlled quantity.
[0150] The actuator control section 15 in this example is connected
with the multifunction piezoelectric actuator 100 via a single line
representing the leads L1, L2, L6, and L7 shown in FIG. 7A. The
actuator control section 15 determines a command voltage on the
basis of the control target value y0 or F0 given to the actuator
control section 15 in advance, and applies the command voltage to
the laminated piezoelectric substance groups 14a and 14b
functioning as the actuator in the multifunction piezoelectric
actuator 100.
[0151] A connection between the above-described multifunction
piezoelectric actuator 100 and the detection operation unit 17' is
made by a single line representing the leads L3, L4, and L5 shown
in FIG. 7A. The detection operation unit 17' is an example of
detector. The detection operation unit 17' converts a detection
voltage Vd output from the multifunction piezoelectric actuator 100
into two control quantities. The detection operation unit 17' is
provided in advance with functions y=f(v) and F=g(v) defining a
relation between the detection voltage Vd (=v) and the displacement
y or between the detection voltage Vd (=v) and the force F or a
conversion table.
[0152] The conversion table stores for example the displacement
y=0.2, 0.4, 0.6, 0.8 . . . [mm] and the force F=3, 6, 9, 12 . . .
[gf] for voltage v=1, 2, 3, 4 . . . . Let y1 or F1 be a control
quantity after conversion. The comparator 19 is connected to the
detection operation unit 17' to compare the control quantity y1 or
F1 after conversion with the control target value (y0, F0). A
result of the comparison is output to the actuator control section
15 to determine a new command voltage.
[0153] The detection voltage Vd occurring in the laminated
piezoelectric substance group 14c functioning as force detecting
sensor as a result of the actuator 100 being in operation is output
to the detection operation unit 17'. The detection voltage Vd is
converted into a necessary control quantity y1 or F1 by the
detection operation unit 17', and then compared with the target
value (y0, F0) at the comparator 19. On the basis of a result of
the comparison, the actuator control section 15 determines a new
command voltage. The new command voltage is applied to the
laminated piezoelectric substance groups 14a and 14b functioning as
actuator in the multifunction piezoelectric actuator 100.
[0154] While the piezoelectric substances functioning as the
actuator and the piezoelectric substances functioning as the sensor
in the multifunction piezoelectric actuator 100 according to the
third embodiment of the present invention are mechanically within
an identical structure and close to each other, the piezoelectric
substances functioning as the actuator and the piezoelectric
substances functioning as the sensor are electrically independent
of each other. In this respect, a part of the multifunction
piezoelectric actuator 100 functioning as a piezoelectric bimorph
type actuator can be used as a force detecting sensor. Therefore
the function of the actuator and the function of the force
detecting sensor can be used at the same time. In addition, as
compared with a case where the actuator 100 and the force detecting
sensor are provided separately from each other, a mounting space is
shared and thus an electronic device can be made more compact.
[0155] FIGS. 9A, 9B, and 9C, FIGS. 10A, 10B, and 10C, and FIGS. 13A
to 15B are process diagrams representing examples (1 to 5) of
formation of the multifunction piezoelectric actuator 100. FIGS.
11A, 11B, 11C, and 11D and FIG. 12 are diagrams showing an example
of electrode patterns and an example of lamination of a film-shaped
piezoelectric substance, the diagrams being supplementary to the
process diagrams.
[0156] In the third embodiment, a laminate having the upper part
surface electrode 11, the lower part surface electrode 12, the
central electrode 13, and the 16 layers of the electrodes IE1 to
IE16 as shown in FIG. 6 is formed. Then the laminate is divided
electrically to demarcate at least three laminated piezoelectric
substance groups 14a, 14b, and 14c. The central electrode 13 is
drawn out from the piezoelectric substances #9 and #10 situated at
a center of the laminated piezoelectric substance group 14c after
demarcation. Other electrodes IE6 and IE11 are drawn out from the
piezoelectric substances #6 and #12 situated in the laminated
piezoelectric substance group 14c at the center of the laminate.
That is, at least the two electrodes IE6 and IE11 and the one
central electrode 13 are drawn out from the laminated piezoelectric
substance group 14c situated at the center.
[0157] With these manufacturing conditions, in FIG. 9A,
piezoelectric substance material such as a ceramic in a powder form
or the like, a solvent, a binder, a dispersing agent and the like
are put into a predetermined mixer 101 and mixed with each other to
form a mixed slurry 102. As the solvent, acetone, toluene, ethanol,
MEK or the like is used. As the binder, polyvinyl, alcohol,
polyethylene or the like is used. About 10 w % of the binder is
used.
[0158] Next, in FIG. 9B, the mixed slurry 102 is made to flow out
into a uniform thickness by using a doctor blade 103. The film
thickness is about 30 .mu.m to 50 .mu.m, for example. Thereafter,
the solvent is evaporated and dried, whereby a green sheet is
formed. For example, a drying room 104 is maintained at normal
temperature or room temperature of about 50 to 80.degree. C., and
the mixed slurry 102 made to flow out into the uniform thickness is
allowed to stand for a few ten minutes to be dried. The mixed
slurry 102 from which the solvent is removed forms a film-shaped
piezoelectric substance (green sheet) 100'.
[0159] Thereafter the film-shaped piezoelectric substance 100' is
cut into a predetermined size. In FIG. 9C, the film-shaped
piezoelectric substance 100' is mounted in a predetermined frame
105. The film-shaped piezoelectric substance 100' is cut into a
square shape and a size of about 200 mm.times.200 mm.
[0160] Next, in FIG. 10A, openings are provided at predetermined
positions of the film-shaped piezoelectric substance 100'
previously mounted in the frame 105 to form through holes not shown
in the figure. The through holes are made to electrically connect a
main electrode IE in each layer to a wiring electrode (land)
provided on a surface. An opening diameter is about 0.1 .mu.m.phi.
to 0.2 .mu.m.phi..
[0161] Further, in FIG. 10B, an electrode material is printed at a
predetermined position of the film-shaped piezoelectric substance
100' in which the through holes have previously been made. The
electrode printing is performed by screen printing. As the
electrode material, a Ag--Pd alloy paste is used. For printing of
an electrode of each layer, screens that serve to provide four
kinds of electrode patterns P1 to P4 shown in FIG. 11A to 11D are
prepared. Basically, one main electrode IE and four wiring
electrodes (lands), for example, are arranged on each screen. The
lands are aligned with opening parts (through holes) for interlayer
connection. The screens are formed such that an electrode IE is
connected to one of the lands R1, R2, R3, and R4 situated at
respective different positions in each layer.
[0162] In the electrode pattern P1 shown in FIG. 11A, the main
electrode IE and the first land R1 are connected to each other. The
electrode pattern P1 is applied to the upper part surface electrode
11, the electrode IE2, and the electrode IE4 in the laminated
piezoelectric substance group 14a. The first land R1 forms the
terminal 16a. The electrode pattern P1 is applied to the lower part
surface electrode 12, the electrode IE15, and the electrode IE13 in
the laminated piezoelectric substance group 14b. The land R1 forms
the terminal 16g.
[0163] In the electrode pattern P2 shown in FIG. 11B, the main
electrode IE and the second land R2 are connected to each other.
The electrode pattern P2 is applied to the electrodes IE1, IE3, and
IE5 in the laminated piezoelectric substance group 14a. The land R2
forms the terminal 16b. The electrode pattern P2 is applied to the
electrodes IE16, IE14, and IE12 in the laminated piezoelectric
substance group 14b. The land R2 forms the terminal 16f.
[0164] In the electrode pattern P3 shown in FIG. 11C, the main
electrode IE and the third land R3 are connected to each other. The
electrode pattern P3 is applied to the electrodes IE6 and IE8 in
the laminated piezoelectric substance group 14a. The land R3 forms
the terminal 16c. The electrode pattern P3 is applied to the
electrodes IE9 and IE11 in the laminated piezoelectric substance
group 14b. The land R3 forms the terminal 16e.
[0165] In the electrode pattern P4 shown in FIG. 11D, the main
electrode IE and the fourth land R4 are connected to each other.
The electrode pattern P4 is applied to the electrode IE7 in the
laminated piezoelectric substance group 14a. The land R4 is
connected to the central electrode 13 to form the terminal 16d. The
electrode pattern P4 is applied to the electrode IE10 in the
laminated piezoelectric substance group 14b. The land R4 is
connected to the above-mentioned central electrode 13 to form the
terminal 16d. Incidentally, the through holes made in FIG. 10A are
made in substantially central parts of the lands R1 to R4. When the
electrodes are printed, printing is preferably repeated a plurality
of times in order to supply a sufficient amount of electrode
material inside the through holes.
[0166] Thereafter, in FIG. 10C, a predetermined number of sheets of
the film-shaped piezoelectric substance 100' previously printed
with the electrode material are laminated into layers in parallel
with bonding surfaces. In this example, the laminated piezoelectric
substance group 14a is formed by nine sheets of the film-shaped
piezoelectric substance 100' printed with the electrode material.
Similarly, the laminated piezoelectric substance group 14b is
formed by nine sheets of the film-shaped piezoelectric substance
100'.
[0167] In this example, as shown in FIG. 12, both the laminated
piezoelectric substance group 14a and the laminated piezoelectric
substance group 14b are formed by laminating the film-shaped
piezoelectric substances 100' in order of the electrode patterns
P1, P2, P1, P2, P1, P2, P3, P4, and P3 from the top. By this
lamination, an identical electrode pattern (both the main electrode
IE and the land) can be assigned to every other layer in each of
functional units of the actuator and the force detecting sensor.
Therefore internally homogeneous electrode patterns can be
connected. FIG. 12 is a sectional view showing an example of
formation of a through hole part. The lands R1 to R4 in each layer
are connected by the electrode material filled into the through
holes. This allows a point of feeding to the main electrode IE in
each layer to be drawn out to an upper part surface layer.
[0168] Next, in FIG. 13A, the nine sheets of the film-shaped
piezoelectric substance 100' previously printed with the electrode
material are subjected to thermocompression bonding to form a green
sheet (laminated material) 100'' in a laminated form. As conditions
of thermocompression at this time, the temperature is about
60.degree. C. to 100.degree. C., applied pressure is about 100
kg/cm.sup.2, and a thermocompression bonding time is about a few
ten minutes.
[0169] Then, in FIG. 13B, the green sheet 100'' in the laminated
form resulting from the previous thermocompression bonding is cut
into a predetermined size. For example, a cutting device not shown
in the figure is used to cut the green sheet 100'' into strips.
This is to obtain the laminated piezoelectric substance group 14a
and the laminated piezoelectric substance group 14b and the like.
Then, in FIG. 13C, the green sheet 100'' in the laminated form are
brought into the drying room 104 to remove the binder from the
green sheet 100'' in the drying room 104. As drying conditions in
this case, the temperature is maintained at normal temperature or
room temperature of about 400.degree. C. to 500.degree. C., and the
green sheet 100'' is allowed to stand for a few ten minutes for
degreasing. In practice, the temperature is increased to about
400.degree. C. to 500.degree. C. over a few days while a rate of
the temperature increase is controlled in a furnace.
[0170] In FIG. 14A, the green sheet 100'' in the laminated form
from which the binder has previously been removed is brought into a
firing device 106 to be fired. As firing conditions in this case, a
firing temperature is about 1000.degree. C. to 1200.degree. C., and
a firing time is about 60 minutes. At this time, a degreasing
process is similarly performed, and the temperature is increased to
about 1000.degree. C. to 1200.degree. C. over a few days while a
rate of the temperature increase is controlled in the firing
furnace.
[0171] Thereafter, in FIG. 14B, the previously fired green sheet
100'' in the laminated form is cut by a grindstone 107 to form
individual laminated piezoelectric substance groups 14a and 14b.
Reference numeral 40 denotes a path of the grindstone 107. The
grindstone 107 goes around the green sheet 100'' on a front surface
and a back surface of the green sheet 100'', and thus cuts the
green sheet 100''. The laminated piezoelectric substance group 14a
as shown in FIG. 14C is thereby obtained. A laminated piezoelectric
substance group 14a is used as the laminated piezoelectric
substance group 14b.
[0172] Then, in FIG. 15A, a central electrode 13 of a predetermined
size is prepared, and the laminated piezoelectric substance groups
14a and 14b are bonded to both sides of the central electrode 13.
At this time, the laminated piezoelectric substance group 14a is
bonded to one surface of the central electrode 13, and the
laminated piezoelectric substance group 14b is bonded to the other
surface of the central electrode 13. The laminated piezoelectric
substance group 14b is bonded to the other surface of the central
electrode 13 such that the laminated piezoelectric substance group
14b faces in an opposite direction to that of the laminated
piezoelectric substance group 14a, that is, an upper part surface
layer of the laminated piezoelectric substance group 14b to which
layer a point of feeding to the main electrode IE in each layer is
drawn out faces downward. As a bonding material, an epoxy resin or
a UV bonding agent is used.
[0173] Thereafter, in FIG. 15B, leads L1 to L7 necessary for the
multifunction piezoelectric actuator to function as a piezoelectric
actuator and a force detecting sensor are soldered to the lead
electrodes (lands) provided on the surface. The land R1 of the
laminated piezoelectric substance group 14a forms the terminal 16a.
The lead L1 is joined to the terminal 16a. The land R2 of the
laminated piezoelectric substance group 14a forms the terminal 16b.
The lead L2 is joined to the terminal 16b. The land R3 of the
laminated piezoelectric substance group 14a forms the terminal 16c.
The lead L3 is joined to the terminal 16c. The terminal 16d is
provided to the central electrode 13. The lead L4 is joined to the
terminal 16d.
[0174] The land R3 of the laminated piezoelectric substance group
14b forms the terminal 16e. The lead L5 is joined to the terminal
16e. The land R2 of the laminated piezoelectric substance group 14b
forms the terminal 16f. The lead L6 is joined to the terminal 16f.
The land R1 of the laminated piezoelectric substance group 14b
forms the terminal 16g. The lead L7 is joined to the terminal 16g.
Thus, the multifunction piezoelectric actuator 100 as shown in FIG.
15B is completed. Thereafter a process of polarizing the
piezoelectric elements is performed as required.
[0175] Thus, according to a method of manufacturing the
multifunction piezoelectric actuator 100 according to the third
embodiment, a laminate having the upper part surface electrode 11,
the lower part surface electrode 12, the central electrode 13, and
the 16 layers of the electrodes IE1 to IE16 is formed. Then the
laminate is divided electrically to demarcate at least three
laminated piezoelectric substance groups 14a, 14b, and 14c. The
central electrode 13 is drawn out from the piezoelectric substances
#9 and #10 situated at a center of the laminated piezoelectric
substance group 14c after demarcation. Other electrodes IE6 and
IE11 are drawn out from the piezoelectric substances #6 and #12
situated in the laminated piezoelectric substance group 14c at the
center of the laminate.
[0176] Therefore the piezoelectric bimorph type actuator and the
force detecting sensor can be formed within an identical structure.
In addition, a point of feeding to the main electrode IE in each
layer can be drawn out to an upper part surface layer and a lower
part surface layer. It is thus possible to provide the
multifunction actuator 100 of a low voltage driving type that
enables the function of the actuator and the function of the force
detecting sensor to be used simultaneously. Thereby, as compared
with a case where the piezoelectric actuator and the force
detecting sensor are provided separately from each other, a
mounting space is shared and thus an electronic device can be made
more compact.
[0177] While in the third embodiment, description has been made of
a case where the function of the actuator and the function of the
sensor are incorporated in the multifunction piezoelectric actuator
100 from the beginning, the present invention is not limited to
this. When a charge accumulating function or the like as another
function is incorporated into the laminate, for example, screens
that serve to provide seven kinds of electrode patterns P1 to P7 as
shown in FIG. 16A to 16G are desirably prepared in advance. Each of
seven main electrodes IE of the electrode patterns P1 to P7 shown
in FIG. 16A to 16G can be drawn out to the upper part surface layer
via lands R1 to R7. In addition, by arbitrarily making a short
circuit between the lands R1 to R7, the electrodes can be connected
in a programmable manner, and thus multiple functions can be
incorporated.
[0178] FIG. 17A is a perspective view of an example of lamination
of another film-shaped piezoelectric substance. Lands R1 to R7
shown in FIG. 17A are drawn out to an upper part surface layer of
an electrode pattern P1. FIG. 17B is a sectional view of an example
of formation of a through hole part of the other film-shaped
piezoelectric substance. The lands R1 to R7 in each layer are
connected by electrode material filled into through holes. This
enables all points of feeding to main electrodes IE in seven layers
to be drawn out to the upper part surface layer of the electrode
pattern P1.
[0179] FIGS. 18A and 18B are perspective views of an example of
structure of a portable terminal device 200' to which a first
input-output device according to a fourth embodiment is
applied.
[0180] The portable terminal device (PDA) 200' shown in FIG. 18A is
an example of an electronic device, and has a first input-output
device 60' according to the fourth embodiment of the present
invention. The portable terminal device 200' is suitable for
application to remote controllers of various electronic devices,
electronic dictionaries, portable telephones, digital cameras and
the like. The portable terminal device 200' has a main body 20. The
main body 20 has a plurality of function keys 21 to 28. In addition
to these function keys 21 to 28, the main body 20 has the
input-output device 60' with a tactile function.
[0181] The input-output device 60' has a multifunction
piezoelectric actuator (first piezoelectric composite device) 1
with a touch cover to give vibrational displacements to the touch
cover 28. The touch cover 28 is provided so as to cover a detecting
electrode. A constricted part 29 is formed at boundaries between
the main body 20 and the touch cover 28. The constricted part 29 is
formed to provide this part with a diaphragm (spring) effect for
easy deformation of the casing. The touch cover 28 is formed by an
insulative resin member. Injection integral molding may be
performed using a resin member of the main body 20 so as to form
the touch cover 28 as a part of the casing. The multifunction
piezoelectric actuator 1 is attached to a depression part in a side
surface of the main body 20 by bonding or the like, for example. In
this example, an actuator function of the multifunction
piezoelectric actuator 1 is used to provide a tactile sense to a
user, and a sensor function of the multifunction piezoelectric
actuator 1 is used as section for inputting switch ON/OFF
information from the user.
[0182] The multifunction piezoelectric actuator 1 forms tactile
sense providing and information determining section. The
multifunction piezoelectric actuator 1 operates to provide a
tactile sense to a finger 30 of the user pressing the touch cover
28, and also detect an external force applied to the touch cover 28
at a contact position of the finger 30 of the operator and then
output a force detection signal (detection voltage Vd). The force
detection signal determines switch ON/OFF input information when
the touch cover 28 is pressed (first input-output device).
[0183] The multifunction piezoelectric actuator 1 has a feeding
electrode 2, a common electrode 6, a detecting electrode 8, a
piezoelectric element 3 joined between the feeding electrode 2 and
the common electrode 6, and a piezoelectric element 7 joined
between the common electrode 6 and the detecting electrode 8. In
the multifunction piezoelectric actuator 1, a predetermined voltage
is supplied between the feeding electrode 2 and the common
electrode 6, and a force detection signal based on an external
force applied to the touch cover 28 is extracted from the detecting
electrode 8 (first piezoelectric composite device). That is, the
multifunction piezoelectric actuator 1 forms an example of input
section, and operates to detect a touch of the finger 30 of the
operator as an example of an operating object and output switch ON
information or switch OFF information. For example, when the finger
30 of the operator touches the touch cover 28 and presses the touch
cover 28, a pressing force F' is detected, and switch ON
information (or switch OFF information) is output.
[0184] FIG. 19 is a circuit diagram showing an example of
configuration of a control system of the first input-output device
60'. The first input-output device 60' shown in FIG. 19 includes
the multifunction piezoelectric actuator 1, the touch cover 28, and
a control device 50'. In the figure, a part shown in a wave shape
has a diaphragm. The touch cover 28 covers the entire surface of
the detecting electrode 8, and the periphery of the touch cover 28
is engaged with the main body 20 via the diaphragm in such a manner
as to be movable vertically.
[0185] The control device 50' in this example includes a driver IC
57 such as an amplifier or the like and a comparator 58 such as an
operational amplifier or the like. The driver IC 57 is connected to
the feeding electrode 2. The driver IC 57 feeds a predetermined
voltage Va between the feeding electrode 2 and the common electrode
6 according to a control signal Sin set from a higher-level control
system in advance. The comparator 58 is connected to the detecting
electrode 8. The comparator 58 detects a force detection signal
Sout (detection voltage Vd) from the detecting electrode 8, and
then outputs the force detection signal Sout to the higher-level
control system. The higher-level control system controls the
feeding to the feeding electrode 2 on the basis of the force
detection signal Sout obtained from the comparator 58.
[0186] The main body 20 shown in FIG. 18A has display section 62.
The display section 62 displays input information. The higher-level
control system detects a pressing force F' of the finger 30 of the
operator selecting an input item displayed by the display section
62, and determines that the input item is selected on the basis of
the detected pressing force F' of the finger 30 of the operator.
The higher-level control system determines that the input item is
selected on the basis of the force detection signal obtained from
the detecting electrode 8 shown in FIG. 19. Then the higher-level
control system outputs a control signal Sin to the control device
50'. The control device 50' controls the feeding to the feeding
electrode 2 on the basis of the control signal Sin. By controlling
the feeding, a tactile stimulus is given to the finger 30 of the
operator.
[0187] Thus, according to the portable terminal device 200' to
which the input-output device 60' according to the fourth
embodiment is applied, the multifunction piezoelectric actuator
(first piezoelectric composite device) 1 according to an embodiment
of the present invention is applied to the tactile sense providing
and information determining section. The multifunction
piezoelectric actuator 1 has the feeding electrode 2, the common
electrode 6, the detecting electrode 8, the piezoelectric element 3
joined between the feeding electrode 2 and the common electrode 6,
and the piezoelectric element 7 joined between the common electrode
6 and the detecting electrode 8. With this as a precondition, the
first input-output device 60' detects a pressing force F' at a
contact position of the finger 30 of the operator, and then outputs
switch ON or OFF information. The multifunction piezoelectric
actuator 1 provides a tactile sense to the finger 30 of the
operator pressing the touch cover 28, and also detects the pressing
force F' at the contact position of the finger 30 of the operator
and determines the switch ON/OFF information.
[0188] Hence, since a part of the piezoelectric composite device
functioning as a piezoelectric bimorph type actuator can be used as
a force detecting sensor for determining the information, the
function of the actuator and the function of the force detecting
sensor can be used at the same time. In addition, as compared with
a case where the actuator and the force detecting sensor are
provided separately from each other, a mounting space is shared and
thus the first input-output device 60' and the portable terminal
device 200' can be made more compact.
[0189] FIG. 20 is a perspective view of an example of structure of
a portable terminal device 200 to which an input-output device
according to a fifth embodiment is applied.
[0190] The portable terminal device (PDA) 200 shown in FIG. 20 is
an example of an electronic device, and has an input-output device
60 according to the fifth embodiment of the present invention. The
portable terminal device 200 is suitable for application to remote
controllers of various electronic devices, electronic dictionaries,
portable telephones, digital cameras and the like. The portable
terminal device 200 has a main body 20. The main body 20 has a
plurality of function keys 21 to 28. In addition to these function
keys 21 to 28, the main body 20 has the input-output device 60
enabling a touch typing system.
[0191] The input-output device 60 has a touch panel 61, display
section 62, four multifunction piezoelectric actuators 100a to
100d, and the like to give vibrational displacements to the touch
panel 61. The touch panel 61 forms an example of input section, and
operates to detect a contact position of a finger 30 of an operator
as an example of an operating object and output input information.
For example, when the finger 30 of the operator selects and touches
an icon or the like displayed by the display section 62, input
information is output.
[0192] The display section 62 displays a menu screen and input
items such as icon buttons and the like. A liquid crystal display
device or an EL (electroluminescence) element is used as the
display section 62. The multifunction piezoelectric actuators 100a
to 100d form tactile sense providing and information determining
section. The multifunction piezoelectric actuator 1 operates to
provide a tactile sense to a finger of the user operating the touch
panel 61, and also detect an external force applied to the touch
panel 61 at a contact position of the finger 30 of the operator and
then output a force detection signal.
[0193] The force detection signal determines the input information
selected by the touch panel 61. The multifunction piezoelectric
actuators 100a to 100d are applied to the input-output device 60.
In this example, an actuator function of the multifunction
piezoelectric actuator 100 is used to provide a tactile sense to
the user, and a sensor function of the multifunction piezoelectric
actuator 100 is used as section for collecting input information
from the user (second input-output device).
[0194] FIG. 21 is a sectional view of an example of structure of
the input-output device 60 in the portable terminal device 200
according to the fifth embodiment, the input-output device 60
including the touch panel 61, the display section 62, and the
multifunction piezoelectric actuators 100a and 100b. The display
section 62 is disposed under the touch panel 61. Input items
displayed by the display section 62 are passed through the touch
panel 61 to be presented to the user.
[0195] The display section 62 is disposed inside a supporting frame
71 such that a display screen is exposed. The multifunction
piezoelectric actuators 100a and 100b and the like are disposed at
four corners on the supporting frame 71 (only two corners are shown
in FIG. 21). The multifunction piezoelectric actuator 100a on a
left side is disposed with two supporting parts 73a and 73b on the
supporting frame 71 as a pillow. A supporting part 73c is provided
to a central part of the actuator 100a. The supporting part 73b is
disposed on a back side of an upper end part 72a of the actuator
100a. The supporting part 73a is disposed at a position adjacent to
a terminal 16. The terminal 16 forms the terminals 16a to 16g shown
in FIG. 15B.
[0196] The multifunction piezoelectric actuator 100b on a right
side is disposed with two supporting parts 74a and 74b on the
supporting frame 71 as a pillow. A supporting part 74c is provided
to a central part of the actuator 100b. The supporting part 74a is
disposed on a back side of an upper end part 72b of the actuator
100b. The supporting part 74b is disposed at a position adjacent to
a terminal 16. The terminal 16 forms the terminals 16a to 16g shown
in FIG. 15B.
[0197] The touch panel 61 is disposed on the supporting parts 73c
and 74c. The touch panel 61 is fixed to the supporting frame 71 by
a side supporting member 70 having an upper part in an inverted
L-shape. Seal members 75a and 75b are inserted between the touch
panel 61 and upper end parts 70a and 70b of the side supporting
member 70. The supporting parts 73a to 73c and the supporting parts
74a to 74c form a vibration transmitting mechanism 64.
[0198] The multifunction piezoelectric actuators 100a and 100b are
each connected to a control device 50. For example, the terminal 16
of the actuator 100a is connected with the seven leads L1 to L7
shown in FIG. 15B. The leads L1 to L7 are connected to the control
device 50. The terminal 16 of the multifunction piezoelectric
actuator 100b is connected with the seven leads L1 to L7 shown in
FIG. 15B. The leads L1 to L7 are also connected to the control
device 50.
[0199] The control device 50 applies a command voltage (actuator
driving voltage) Va to laminated piezoelectric substance groups 14a
and 14b functioning as an actuator in the multifunction
piezoelectric actuator 100a via the leads L1 to L7. A bend
deformation (R) at this time is converted into a displacement U in
a Z-direction of the touch panel 61. For example, when the control
device 50 generates the actuator driving voltage Va and supplies
the actuator driving voltage Va through the leads L1, L2, L6, and
L7 connected to the multifunction piezoelectric actuator 100a to
the piezoelectric substances #1 to #5 and the piezoelectric
substances #14 to #18 of the laminated piezoelectric substance
group 14a and the laminated piezoelectric substance group 14b via
the terminals 16a, 16b, 16f, and 16g shown in FIG. 6, the laminated
piezoelectric substance group 14a vibrates so as to elongate, and
the laminated piezoelectric substance group 14b vibrates so as to
contract with the central electrode 13 as a reference. Thus the
multifunction piezoelectric actuator 100a can be operated as an
actuator.
[0200] The control device 50 applies a command voltage Va to
laminated piezoelectric substance groups 14a and 14b functioning as
an actuator in the multifunction piezoelectric actuator 100b via
the leads L1 to L7. A bend deformation (R) at this time is
converted into a displacement U in a Z-direction of the touch panel
61. For example, when the control device 50 generates the actuator
driving voltage Va and supplies the actuator driving voltage Va
through the leads L1, L2, L6, and L7 connected to the multifunction
piezoelectric actuator 100b to the piezoelectric substances #1 to
#5 and the piezoelectric substances #14 to #18 of the laminated
piezoelectric substance group 14a and the laminated piezoelectric
substance group 14b via the terminals 16a, 16b, 16f, and 16g shown
in FIG. 6, the laminated piezoelectric substance group 14a vibrates
so as to elongate, and the laminated piezoelectric substance group
14b vibrates so as to contract with the central electrode 13 as a
reference. Thus the multifunction piezoelectric actuator 100b can
be operated as an actuator.
[0201] FIGS. 22A and 22B are sectional views of an example of
operation when the touch panel in the input-output device 60 is
pressed. The supporting part 73c shown in FIG. 22A forms a
supporting point when the finger 30 of the user presses the touch
panel 61 and the pressing force F causes a bend deformation (R) of
the multifunction piezoelectric actuator 100 as shown in FIG. 22B
in a broken line circle. In the multifunction piezoelectric
actuator 100a and the like, a laminated piezoelectric substance
group 14c functioning as a sensor as shown in FIG. 6 generates a
force detection voltage Vd (voltage signal).
[0202] For example, when an external force is applied to the
piezoelectric substances #7 to #12 of the laminated piezoelectric
substance group 14c, a force detection voltage Vd occurs in the
lead L3 and the lead L5. The force detection voltage Vd is output
to the control device 50. The control device 50 for example detects
the force detection voltage Vd, and outputs the force detection
voltage Vd as a force detection signal Sout to a higher-level
control system. Thus the multifunction piezoelectric actuator 100
can also be operated as a force detecting sensor while the actuator
function of the multifunction piezoelectric actuator 100 is
retained (see FIG. 6).
[0203] FIG. 23 is a block diagram showing an example of
configuration of main parts of the portable terminal device 200.
The portable terminal device 200 shown in FIG. 23 has the control
device 50 and the input-output device 60. The control device 50 for
example includes an analog-to-digital (hereinafter referred to as
A/D) converter 51, a digital-to-analog (hereinafter referred to as
D/A) converter 52, a memory 53, a processor 54, a CPU 55, and a
current amplifier 56.
[0204] The input-output device 60 includes the touch panel 61, the
display section 62, and vibration generating section 63. When a
menu screen or an input item such as an icon button or the like is
pressed, the touch panel 61 for example outputs operation data D3
constituting coordinate input position information to the CPU 55.
The display section 62 displays the menu screen or the input item
such as the icon button or the like on the basis of display data D2
output from the CPU 55.
[0205] The input-output device 60 in this example has the vibration
generating section 63. The vibration generating section 63 has the
four multifunction piezoelectric actuators 100a to 100d, the
vibration transmitting mechanism 64 shown in FIG. 21, and the like.
The multifunction piezoelectric actuators 100a to 100d and the like
are connected to the control device 50. The control device 50
controls feeding to the main electrodes IE of the laminated
piezoelectric substance groups 14a and 14b on the basis of a force
detection voltage Vd obtained from the central electrode 13 of the
laminated piezoelectric substance group 14c shown in FIG. 6 in the
multifunction piezoelectric actuators 100a to 100d.
[0206] The multifunction piezoelectric actuators 100a to 100d are
connected with the A/D converter 51. The A/D converter 51 subjects
the force detection voltage Vd to A/D conversion, and then outputs
digital force detection data Dd. The processor 54 is connected to
the A/D converter 51. The processor 54 operates so as to assist the
CPU 55 in operations and control. For example, the processor 54 is
supplied with the force detection data Dd from the A/D converter
51, determines a vibration waveform pattern on the basis of the
force detection data Dd, and then supplies pattern determining data
Dd' to the CPU 55. A digital signal processor (hereinafter referred
to as a DSP) is used as the processor 54.
[0207] The processor 54 is connected to the memory 53. The memory
53 stores various vibration waveform pattern data D1. The memory 53
for example stores an acknowledgment waveform pattern P10
indicating reception of an operation, and vibration control
waveform patterns P11, P12, P13, and P14 providing various tactile
waveforms. The vibration control waveform pattern P11 is a
so-called rectangular wave pattern generating a click sense, or for
example a sense of stiffness. The vibration control waveform
pattern P12 is a digital waveform pattern that provides a rhythmic
feeling as of a heart beat. The vibration control waveform pattern
P13 is a waveform pattern providing a sense of an operation that
generates continuous movements. The vibration control waveform
pattern P14 is a pattern providing a reaction of an ordinary touch
panel surface, that is, a substantially constant vibrational
displacement.
[0208] The processor 54 is connected to the CPU 55 as well as the
memory 53. The CPU 55 determines a vibration waveform pattern to be
read on the basis of the operation data D3 and the pattern
determining data Dd'. The CPU 55 outputs a pattern reading allowing
instruction Dc to the processor 54. The processor 54 reads the
vibration waveform pattern data D1 from the memory 53 on the basis
of the pattern reading allowing instruction Dc, and then sets the
vibration waveform pattern data D1 in the D/A converter 52.
[0209] The processor 54 is connected to the D/A converter 52. The
D/A converter 52 subjects the vibration waveform pattern data D1
read out by the processor 54 to D/A conversion, and then outputs an
analog vibration control signal Sa to the current amplifier 56. The
current amplifier 56 generates an actuator driving voltage (command
voltage) Va on the basis of the vibration control signal Sa. The
driving voltage Va is supplied to the laminated piezoelectric
substance groups 14a and 14b functioning as actuator in the
multifunction piezoelectric actuators 100a to 100d. Incidentally,
the processor 54, the D/A converter 52, and the current amplifier
56 form the actuator control section 15 shown in FIGS. 7A and
7B.
[0210] Thus, the processor 54 detects a force F of the finger 30 of
the user selecting an input item displayed by the display section
62, and the CPU 55 determines that the input item is selected on
the basis of the force of the finger 30 of the user which force is
detected by the processor 54. For example, the CPU 55 determines
that the input item is selected on the basis of the force detection
voltage Vd obtained from the central electrode 13 of the laminated
piezoelectric substance group 14c via the processor 54, and then
controls feeding to the main electrodes IE of the laminated
piezoelectric substance groups 14a and 14b via the processor 54 to
thereby give a tactile stimulus to the finger 30 of the user
(acknowledging method using a tactile sense).
[0211] An example of control of the portable terminal device 200
will next be described. FIG. 24 is a diagram representing an
example of operation of the portable terminal device 200. In this
example, description will be made of three cases, that is, a case
where the multifunction piezoelectric actuators 100a to 100d and
the like within the input-output device 60 are made to function as
actuator, a case where the multifunction piezoelectric actuators
100a to 100d and the like are made to function as force detecting
sensor, and a case where the multifunction piezoelectric actuators
100a to 100d and the like are made to perform a series of
operations.
[Actuator Function]
[0212] The display section 62 shown in FIG. 24 displays a menu
screen. In this example, four icons 31 to 34 are displayed on the
menu screen. Suppose that the user selects one of the four icons 31
to 34.
[0213] When the finger 30 of the user touches the icon 31, 32, 33,
or 34 displayed on the menu screen via the touch panel 61 in FIG.
24, coordinate position information on a position where the finger
30 of the user touches the icon 31, 32, 33, or 34 is output as
operation data D3 to the CPU 55. The CPU 55 specifies the vibration
control waveform pattern P11 corresponding to the icon that the
finger 30 of the user touches, for example the icon 31. The CPU 55
controls the processor 54 to read the vibration control waveform
pattern P11 corresponding to the icon 31 from the memory 53.
[0214] The processor 54 reads the vibration waveform pattern data
D1 for providing the vibration control waveform pattern P11 from
the memory 53, and then sets the vibration waveform pattern data D1
in the D/A converter 52. The D/A converter 52 subjects the
vibration waveform pattern data D1 read out by the processor 54 to
D/A conversion, and then outputs an analog vibration control signal
Sa to the current amplifier 56. The current amplifier 56 generates
an actuator driving voltage (command voltage) Va on the basis of
the vibration control signal Sa. The driving voltage Va is supplied
to the laminated piezoelectric substance groups 14a and 14b
functioning as actuator in the multifunction piezoelectric
actuators 100a to 100d. Thereby a vibration providing a click sense
corresponding to the icon 31 is generated on the touch panel
surface to be provided as a tactile stimulus to the finger 30 of
the user.
[0215] When the icon 32 is touched, a vibration providing a
rhythmic feeling as of a heart beat, which vibration is based on
the vibration control waveform pattern P12, is generated on the
touch panel surface to be provided as a tactile stimulus to the
finger 30 of the user. When the icon 33 is touched, a vibration
providing a sense of an operation that generates continuous
movements, which vibration is based on the vibration control
waveform pattern P13, is generated on the touch panel surface to be
provided as a tactile stimulus to the finger 30 of the user. When
the icon 34 is touched, only reaction of an ordinary touch panel
surface, that is, a substantially constant vibrational
displacement, based on the vibration control waveform pattern P14,
is generated on the touch panel surface to be provided as a tactile
stimulus to the finger 30 of the user.
[0216] When the user puts the finger out of contact with the touch
panel surface or when the user slides the finger on the touch panel
surface to a position outside an area where the icon 31 or the like
is displayed, the CPU 55 determines at all times whether the icon
is touched on the basis of coordinate position information output
from the touch panel 61 to the CPU 55, and then resets the command
voltage Va for the multifunction piezoelectric actuators 100a to
100d. This reset operation stops the vibration of the touch panel
surface. Thus, the user knows which of the icon 31, 32, 33, and 34
the user is selecting by touching the touch panel surface without
seeing the icon 31, 32, 33, or 34 with his/her eyes. Thus, the
multifunction piezoelectric actuators 100a to 100d and the like can
be operated as actuator.
[Function of Force Detecting Sensor]
[0217] When the finger of the user touches the touch panel in FIG.
24, a pressing force F applied to the touch panel 61 deforms the
multifunction piezoelectric actuators 100a to 100d, so that a force
detection voltage Vd occurs in the laminated piezoelectric
substance group 14c functioning as force detecting sensor (see
FIGS. 22A and 22B). When the user knows by the above-described
method that the finger 30 of the user is on an icon that the user
desires to select, the user for example presses in the touch panel
61 more strongly to select the icon 31 or the like. This operation
of pressing in the touch panel 61 causes a higher force detection
voltage Vd in the laminated piezoelectric substance group 14c
functioning as force detecting sensor.
[0218] The force detection voltage Vd is output to the A/D
converter 51. The A/D converter 51 subjects the force detection
voltage Vd to A/D conversion, and then outputs digital force
detection data Dd. The force detection data Dd is output from the
A/D converter 51 to the processor 54. The processor 54 is supplied
with the force detection data Dd from the A/D converter 51, and
compares a level to be compared which level is based on the force
detection data Dd with a preset threshold level at any time.
[0219] When the level to be compared which level is based on the
force detection data Dd exceeds the threshold level, the CPU 55
determines that the user is selecting (pressing) (has selected
(pressed) the icon 31 or the like. When the level to be compared
does not exceed the threshold level, the CPU 55 determines that the
user is searching for the icon 31 or the like. Thereby the
multifunction piezoelectric actuators 100a to 100d and the like can
be operated also as force detecting sensor.
EXAMPLE OF SERIES OF OPERATIONS OF ACTUATOR AND FORCE DETECTING
SENSOR
[0220] FIGS. 25A to 25C are diagrams representing an example of a
series of operations and an example of waveforms in the
input-output device 60. In FIGS. 25B and 25C, an axis of abscissas
represents time t and the contact position X of the finger 30. An
axis of ordinates represents a combined value [V] of the actuator
driving voltage Va based on the vibration control waveform pattern
P10 to P13 and the force detection voltage Vd.
[0221] In the fifth embodiment, a case in which the user searches
for the icon 33 while sliding the finger 30 from a left side to a
right side on the icon 31, and selects the icon 33 will be taken as
an example. A series of operations of the multifunction
piezoelectric actuators 100a to 100d in this case will be described
using the function of the actuator based on the specific vibration
control waveform patterns P10 to P13 and the force detection
voltage Vd detected by the function of the force detecting
sensor.
[0222] In FIG. 25A, the user slides the finger 30 of the user in a
direction of a right arrow from a position (A) in the figure, that
is, a start point (A) at a left end part of the icon 31 to find the
desired icon 33. The user performs a selecting operation at a time
when (at a position where) the finger 30 reaches the desired icon
33.
[0223] With these operating conditions, the user does not touch
either of the icons 31 and 33 at the start point (A), that is, at a
time t0, and therefore level of the actuator driving voltage Va
shown in FIG. 25B is zero. While the touch panel surface shows
displacements in proportion to the actuator driving voltage Va
based on the vibration control waveform pattern P11 or the like, no
vibration occurs with the actuator driving voltage Va having a zero
level at this time. In this case, the user does not feel anything.
As for the force detection voltage Vd, on the other hand, since the
user touches the finger 30 to the touch panel surface only lightly,
a corresponding force detection voltage Vd appears. The force
detection voltage Vd at this time is lower than a threshold value,
as shown in FIG. 25C.
[0224] Next, when the user slides the finger 30 and the finger 30
reaches the icon 31 at a position x1 at a time t1, the processor 54
reads the vibration control waveform pattern P11 defined in advance
from the memory 53, and then sets the vibration control waveform
pattern P11 in the D/A converter 52. The D/A converter 52 subjects
the vibration waveform pattern data D1 read out by the processor 54
to D/A conversion, and then outputs an analog vibration control
signal Sa to the current amplifier 56. The current amplifier 56
generates an actuator driving voltage (command voltage) Va on the
basis of the vibration control signal Sa. The driving voltage Va is
supplied to the laminated piezoelectric substance groups 14a and
14b functioning as actuator in the multifunction piezoelectric
actuators 100a to 100d. Thereby a vibration providing a click sense
corresponding to the icon 31 is generated on the touch panel
surface to be provided as a tactile stimulus to the finger 30 of
the user.
[0225] The force detection voltage Vd at this time is a result of
superimposing the actuator driving voltage Va for deforming the
multifunction piezoelectric actuators 100a to 100d and the like on
the basis of the vibration control waveform pattern P11 on the
force detection voltage resulting from the user touching the touch
panel 61. The force detection voltage Vd is converted into force
detection data Dd.
[0226] Further, when the user moves the finger 30 to the right
side, the finger 30 goes away from the icon 31 at a position x2 at
a time t2, and therefore the same state as at the start point (A)
reappears. When the finger 30 goes onto the icon 33 at a position
x3 at a time t3, the vibration control waveform pattern P13
corresponding to the icon 33 is set (output) from the memory 53 to
the D/A converter 52. The D/A converter 52 subjects the vibration
waveform pattern data D1 read by the processor 54 to D/A
conversion, and then outputs an analog vibration control signal Sa
to the current amplifier 56.
[0227] The current amplifier 56 generates an actuator driving
voltage (command voltage) Va on the basis of the vibration control
signal Sa. The driving voltage Va is supplied to the laminated
piezoelectric substance groups 14a and 14b functioning as actuator
in the multifunction piezoelectric actuators 100a to 100d. Thereby
a vibration providing a sense of an operation that generates
continuous movements, which vibration is based on the vibration
control waveform pattern P13, is generated on the touch panel
surface to be provided as a tactile stimulus to the finger 30 of
the user.
[0228] The user presses the touch panel surface at a position x4 at
a time t4 to select the icon 33. Then, the value of the force
detection voltage Vd is increased in proportion to a pressing force
F. When the value of the force detection voltage Vd exceeds the
preset threshold value Vth shown in FIG. 25C, the CPU 55 determines
that selection is made by the user. Making this determination, the
CPU 55 reads, from the memory 53, the acknowledgment waveform
pattern P10 indicating that an operation by the user is received,
and then outputs the acknowledgment waveform pattern P10 to the D/A
converter 52. Thus, a vibration with a sharp rising edge is
generated on the basis of the acknowledgment waveform pattern P10
so that the user can be informed (confirm) that the selection by
the user is received by the CPU 55.
[0229] Thus, the input-output device 60 according to an embodiment
of the present invention is applied to the portable terminal device
200 according to the fifth embodiment, and the multifunction
piezoelectric actuators 100a to 100d according to an embodiment of
the present invention are applied to the input-output device 60.
The multifunction piezoelectric actuators 100a to 100d detect a
force F at the contact or pressing position of the finger 30 of the
user and input acknowledgement information, and also provide a
tactile sense to the finger 30 of the user operating the touch
panel 61.
[0230] Hence, since a part of the multifunction piezoelectric
actuator 100 functioning as a piezoelectric bimorph type actuator
can be used as a force detecting sensor, the function of the
actuator and the function of the force detecting sensor can be used
at the same time. In addition, when the function of the force
detecting sensor is applied to closed loop control, since the force
detecting sensor and the actuator are mechanically within an
identical structure but electrically independent of each other,
optimum control can be realized.
[0231] Furthermore, as compared with a case where an actuator
itself is used as a force detecting sensor as in a system in the
past, since the command voltage Va to the actuator and the force
detection voltage Vd from the force detecting sensor do not need to
be electrically separated from each other, an actuator control
circuit can be formed simply and inexpensively. Thus, as compared
with a case where the actuator and the force detecting sensor are
provided separately from each other, a mounting space is shared and
therefore the input-output device 60 and the portable terminal
device 200 can be reduced in size and cost.
[0232] When the function of the force detecting sensor is used to
detect a force F of the user operating the portable terminal device
200, for example, the transmission of information (a type of menu,
button or the like) by a tactile sense to the user and an input
process for receiving a selection on a menu screen of an icon or
the like by the user can be realized by the multifunction
piezoelectric actuator within an identical structure.
[0233] Incidentally, the operation of the user who determines a
type of an icon button or the like only by touching the touch panel
61 and selects an appropriate button or the like is a so-called
"touch typing operation" in which the user does not need to look at
the display screen. When the portable terminal device 200 is
mounted in a vehicle, in particular, this contributes to safety of
the user because driving operation is not visually hindered.
[0234] In addition, when the "touch typing operation" is applied to
not only devices mounted in vehicles but also operating remote
controllers of large television sets and the like operation of
which has become complicated due to recent increase in the number
of broadcasting and video distribution channels, it is possible to
perform a complicated operation by hand while fixing eyes on a main
setting screen. Therefore operability of the input-output device 60
and the portable terminal device 200 is improved.
[0235] The present invention is very suitable for application to
portable telephones, digital cameras, portable terminals, remote
controllers and the like having a tactile input function.
[0236] It should be understood by those skilled in the art that
various modifications, combinations, sub-combinations and
alterations may occur depending on design requirements and other
factors insofar as they are within the scope of the appended claims
or the equivalents thereof.
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