Piezoelectric element and driving apparatus

Abstract

A piezoelectric element comprises: a first non-extendible and non-contractible portion which neither extend nor contract, the first non-extendible and non-contractible portion being provided at one end of the piezoelectric element; an extendible and contractible portion which extends and contracts; at least one electrode which is provided on a surface of the extendible and contractible portion and is provided so as to extend to a position where a surface of the first non-extendible and non-contractible portion lies; and at least one connecting terminal which is connected to said at least one electrode and is provided in a position where the first non-extendible and non-contractible portion lies.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a driving apparatus according to an embodiment of the invention;

FIG. 2 is an enlarged view of a piezoelectric element in the driving apparatus shown in FIG. 1;

FIG. 3 is a sectional view of a driven member taken along the line III-III in FIG. 1;

FIG. 4 is a diagram showing a driving circuit in the driving apparatus shown in FIG. 1;

FIGS. 5A and 5B are diagrams showing waveforms of input signals which are inputted into the driving circuit shown in FIG. 4;

FIGS. 6A and 6B are diagrams showing waveforms of output signals which are outputted from the driving circuit shown in FIG. 4; and

FIG. 7 is an explanatory diagram of the related-art technique.

Claims

1. A piezoelectric element comprising: a first non-extendible and non-contractible portion which neither extend nor contract, the first non-extendible and non-contractible portion being provided at one end of the piezoelectric element;an extendible and contractible portion which extends and contracts;at least one electrode which is provided on a surface of the extendible and contractible portion and is provided so as to extend to a position where a surface of the first non-extendible and non-contractible portion lies; andat least one connecting terminal which is connected to said at least one electrode and is provided in a position where the first non-extendible and non-contractible portion lies.

2. A piezoelectric element as set forth in claim 1, wherein said at least one electrode comprises two electrodes provided in such a way as to sandwich the extendible and contractible portion, andsaid at least one connecting terminal comprises two connecting terminals that are provided to be connected to the two electrodes, respectively, and are both provided on a side of the one end of the piezoelectric element where the first non-extendible and non-contractible portion lies.

3. A driving apparatus comprising: a piezoelectric element;a driving shaft that reciprocates in response to an extension and contraction of the piezoelectric element; anda driven member, frictionally engaged with the driving shaft, that moves along the driving shaft by reciprocating the driving shaft,wherein the piezoelectric element comprises:a first non-extendible and non-contractible portion which neither extend nor contract, the first non-extendible and non-contractible portion being provided at one end of the piezoelectric element;an extendible and contractible portion which extends and contracts;at least one electrode which is provided on a surface of the extendible and contractible portion and is provided so as to extend to a position where a surface of the first non-extendible and non-contractible portion lies; andat least one connecting terminal which is connected to said at least one electrode and is provided in a position where the first non-extendible and non-contractible portions lies.

4. A driving apparatus as set forth in claim 3, wherein said at least one electrode comprises two electrodes provided in such a way as to sandwich the extendible and contractible portion, andsaid at least one connecting terminal comprises two connecting terminals that are provided to be connected to the two electrodes, respectively, and are both provided on a side of the one end of the piezoelectric element where the first non-extendible and non-contractible portion lies.

5. A driving apparatus as set forth in claim 3, wherein the driving shaft is attached to the other end of the piezoelectric element, andthe driving apparatus further comprises a wiring member, attached to the one end of the piezoelectric element, that is to be connected to said at least one connecting terminal.

6. A driving apparatus as set forth in claim 5, wherein the piezoelectric element further comprises a second non-extendible and non-contractible portion provided at the other end of the piezoelectric element,the one end of the piezoelectric element to which the wiring member is attached is made to constitute a free end, andthe first non-extendible and non-contractible portion become heavier than the second non-extendible and non-contractible portion.