Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-09-16
2001-07-31
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S368000, C310S357000
Reexamination Certificate
active
06268684
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric resonator adapted to be vibrated in a longitudinal vibration mode for use in an oscillator or other electronic component, and a piezoelectric component including the piezoelectric resonator.
2. Description of the Related Art
A related piezoelectric resonator adapted to be vibrated in a longitudinal vibration mode is described in Japanese Utility Model Publication No. 59-9627 and Japanese Utility Model Publication No. 59-9628. In this resonator, an electrode provided on one major surface of a piezoelectric-ceramic substrate is divided in two by a linear groove extending in the longitudinal direction. A whole-surface electrode is provided on another major surface of the piezoelectric-ceramic substrate. Longitudinal vibration is excited by applying a signal between the electrodes on both major surfaces.
In order to generate a longitudinal vibration, the piezoelectric-ceramic substrate is uniformly polarized in the thickness direction. The electrode is divided in two by the above-mentioned groove so as to suppress a spurious response caused by the width vibration.
When the above described piezoelectric resonator is used in a surface mounting component as shown in
FIG. 1
, a conductive support member
43
is fixed to the divided electrode
41
provided on a piezoelectric resonator
40
. The support member
43
is connected and fixed to one of the pattern electrodes
45
disposed on a substrate
44
. Further, a whole-surface electrode
42
disposed on the piezoelectric resonator
40
opposite to the divided electrode
41
is connected to the other of the pattern electrodes
47
via the conductive wire
46
. Further, the cover
48
which covers the piezoelectric resonator
44
is bonded to the substrate
44
. However, if the wire
46
is used to connect the whole-surface electrode
42
disposed on the piezoelectric resonator
40
and the other of the pattern electrodes
45
, the number of wiring steps and the number of parts increase.
Moreover, since a land
47
a
for a wire connection must be provided on the substrate
44
, a gap between the wire
46
and the cover
48
must be provided and the width of the substrate
44
must be increased to avoid the connection therebetween. This results in the size of the cover
48
being undesirably increased.
SUMMARY OF THE INVENTION
To overcome the above described problems, preferred embodiments of the present invention provide a piezoelectric resonator which makes the process of electrical connection easy by providing input and output electrodes on one major surface of the piezoelectric resonator and which significantly reduces the number of parts and connection processes required for the resonator.
One preferred embodiment of the present invention provides a piezoelectric resonator including a substantially rectangular shaped piezoelectric substrate having a pair of major surfaces and polarized in the thickness direction, a pair of electrodes respectively disposed on the pair of major surfaces of the piezoelectric substrate, one of the electrodes being multiply divided at a dividing line which extends along the longitudinal direction of the piezoelectric substrate, the piezoelectric substrate being polarized such that two portions of the piezoelectric substrate sandwiching the dividing line are polarized in opposite directions.
In the prior art piezoelectric resonator, a longitudinal vibration is excited by applying an input and an output connection between a pair of electrodes which are disposed on a pair of major surfaces of the piezoelectric substrate. In contrast, in the case of the above described piezoelectric resonator according to a preferred embodiment of the present invention, a longitudinal vibration is excited by applying an input and an output connection between the pair of the divided electrodes, and thereby, at least one pair of electrodes disposed on the pair of major surfaces of the piezoelectric substrate does not have to be wired.
When the above described piezoelectric resonator is connected to an outer conductive member, only one of the major surfaces of the piezoelectric resonator is required to be connected to the outer conductive member. Thus, the connection process becomes simple and the size of the piezoelectric resonator is greatly reduced.
Further, focusing attention on a capacitance of the piezoelectric resonator, the piezoelectric resonator has an equivalent circuit which includes a pair of capacitors connected in series and having small electrode areas. Therefore, the capacitance is significantly lowered and thereby, the power consumption is greatly reduced.
In the above described piezoelectric resonator, one of the electrodes may be divided in two. One of the divided electrodes can function as an input electrode and another of the divided electrodes can function as an output electrode. In this case, the piezoelectric resonator can be arranged to define an oscillator having a simple structure.
In the above described piezoelectric resonator, a relationship 1.0<B/A≦1.5 may be satisfied where A is an area of the input (output) electrode and B is an area of the output (input) electrode. In this case, a longitudinal vibration can be generated efficiently while suppressing spurious response.
Another preferred embodiment of the present invention provides a piezoelectric component including the above described piezoelectric resonator, a pair of conductive support members respectively fixed to nodal portions at the pair of the divided electrodes disposed on the piezoelectric substrate, a pair of pattern electrodes provided on a mounting substrate, wherein the pair of conductive support members are respectively connected and fixed to the pair of pattern electrodes.
According to the above described piezoelectric component, wires which were previously required to be used are unnecessary. Further, a land for a wire connection is not needed on a mounting substrate, and thereby, the width of an mounting substrate is greatly reduced.
If a cover which covers the piezoelectric resonator is provided on the mounting substrate, a piezoelectric surface mounting type component is obtained easily.
Yet another preferred embodiment of the present invention provides a piezoelectric component including the above described piezoelectric resonator, a pair of conductive support members respectively fixed to nodal portions at the pair of the divided electrodes disposed on the piezoelectric substrate, wherein the pair of conductive support members are respectively connected and fixed to a pair of input-output lead terminals.
According to the above described piezoelectric component, it becomes unnecessary to bend a lead terminal in the thickness direction in accordance with a pair of major surfaces of the piezoelectric substrate. As a result, processing of a lead terminal becomes simple and the thickness of the piezoelectric component is greatly reduced.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
REFERENCES:
patent: 4455502 (1984-06-01), Nakatani
patent: 4503352 (1985-03-01), Inoue
patent: 5973442 (1999-10-01), Irie
Dougherty Thomas M.
Keating & Bennett LLP
Murata Manufacturing Co. Ltd
LandOfFree
Piezoelectric resonator and a piezoelectric component... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Piezoelectric resonator and a piezoelectric component..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Piezoelectric resonator and a piezoelectric component... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2463876