US 9,960,339 B2Granted

Piezoelectric actuator

AssigneeFUJIFILM Corporation

InventorTakayuki Naono

Life of this patent

Estimating the term…

Loading patent…

Abstract

A piezoelectric actuator includes a piezoelectric element that includes a piezoelectric unit including a ferroelectric, which has an asymmetric bipolar P-E curve, a capacitor connected to the piezoelectric unit in series, and a resistor connected to the capacitor in series and connected to the ferroelectric in parallel; and a drive unit that inputs a drive waveform Vd, which includes a DC offset component of which polarity is opposite to polarization of the ferroelectric, to the piezoelectric element to drive the piezoelectric element. A value of a coercive electric field Ec1, a value of a coercive electric field Ec2, the capacitance Cs of the capacitor, the capacitance Cpz of the ferroelectric, combined resistance Rp of the resistance of the resistor and the resistance of the ferroelectric, and a fundamental angular frequency ω of the drive waveform satisfy Expressions I to III, wherein 1 / 3 ≦  Ec 1 + Ec 2  /  Ec 1 - Ec 2  Expression ⁢ ⁢ I C s ≥ 1.5 ⁢ ( C pz + 1 ω ⁢ ⁢ R p ) Expression ⁢ ⁢ II R p ≥ - 15 C s + C pz · 1 ln ⁡ ( 0.5 ⁢ ( C s + C pz ) C s ) . Expression ⁢ ⁢ III

Claims9

Dependent claims

A piezoelectric actuator comprising:

a piezoelectric element that includes a piezoelectric unit including a ferroelectric, which has asymmetric bipolar polarization-electric field hysteresis characteristics having two coercive electric field points and having different absolute values of the two coercive electric fields, a capacitor electrically connected to the piezoelectric unit in series, and a resistor electrically connected to the capacitor in series and electrically connected to the ferroelectric in parallel;
and
a drive unit that inputs a drive waveform, which includes a DC offset component of which polarity is opposite to polarization of the ferroelectric, to the piezoelectric element to drive the piezoelectric element,
wherein, of the two coercive electric fields, a value of a coercive electric field Ec1, of which an absolute value is larger, and a value of a coercive electric field Ec2, of which an absolute value is smaller, satisfy the following Expression I, and
wherein capacitance Cs of the capacitor, capacitance Cpz of the ferroelectric, combined resistance Rp of resistance of the resistor and resistance of the ferroelectric, and a fundamental angular frequency ω of the drive waveform satisfy the following Expression II and Expression III:
1
/
3
≤

Ec
1
+
Ec
2

/

Ec
1
-
Ec
2

(
Expression
⁢
⁢
I
)
C
s
≥
1.5
⁢
(
C
pz
+
1
ω
⁢
⁢
R
p
)
(
Expression
⁢
⁢
II
)
R
p
≥
-
15
C
s
+
C
pz
·
1
ln
⁡
(
0.5
⁢
⁢
(
C
s
+
C
pz
)
C
s
)
.
(
Expression
⁢
⁢
III
)

84 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/684,497Filed 23 Aug 2017 · continuation
Priority: JP 2015-03756827 Feb 2015
Published: US 2017/0352796 A17 Dec 2017
Granted: 1 May 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H10N 30/802
Constructional details: circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits
H10N 30/076
By depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing: by vapour phase deposition
H10N 30/20
Piezoelectric or electrostrictive devices: with electrical input and mechanical output, e.g. functioning as actuators or vibrators
H10N 30/2042
Beam type: cantilevers, i.e. having one fixed end