Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2000-09-14
2001-10-23
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S366000, C310S320000
Reexamination Certificate
active
06307305
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric component with leads used as, for example, a piezoelectric resonator or a piezoelectric filter, and more particularly, the present invention relates to a piezoelectric component with leads having an improved bonding structure between a terminal electrode and a lead terminal provided on a piezoelectric body.
2. Description of the Related Art
Various piezoelectric components including leads have been used as piezoelectric resonators and piezoelectric filters. Piezoelectric components including leads have been disclosed, for example, in Japanese Unexamined Utility Model Publication Nos. 2-326 and 6-58620, Japanese Unexamined Patent Application Publication No. 6-252683.
FIG. 17
is a perspective view showing a representative example of a conventional piezoelectric component with leads
51
. The piezoelectric component with leads
51
includes a piezoelectric resonance element
52
and lead terminals
53
and
54
.
As shown in
FIG. 18
, the piezoelectric resonance element
52
includes a piezoelectric plate
55
polarized uniformly in the thickness direction thereof. Vibration electrodes
56
and
57
are provided at the center of first and second main surfaces
55
a
and
55
b
of the piezoelectric plate
55
, respectively, so as to be opposed to each other, with the piezoelectric plate
55
therebetween, on the top and bottom surfaces thereof. The vibration electrodes
56
and
57
are connected to lead-out electrodes
58
and
59
, respectively. The lead-out electrodes
58
and
59
are connected to first and second terminal electrodes
60
and
61
, respectively.
The terminal electrodes
60
and
61
are disposed in the vicinity of end portions of the piezoelectric plate
55
. The lead terminals
53
and
54
include cup portions
53
a
and
54
a
, respectively, having a U-shaped cross section, and terminal lead-out portions
53
b
and
54
b
having a tabular shape. The inner surfaces of the cup portions
53
a
and
54
a
are bonded to the second and first terminal electrodes
61
and
60
, respectively, using solder or a conductive adhesive.
To increase moisture resistance and shock resistance, the portions except the tip portions of the terminal lead-out portions
53
b
and
54
b
of the lead terminals
53
and
54
are coated with resin.
As describe above, the cup portions
53
a
and
54
a
are bonded to the terminal electrodes
61
and
60
, respectively, using solder or a conductive bonding agent. Since solder or a conductive adhesive has fluidity during bonding, however, they flow along the inner surface of the cup portion
53
a
and
54
a
, and often extend to the lead-out electrodes
59
and
58
, respectively. In an extreme case, the solder or conductive adhesive extends to the vibration electrodes
57
and
56
, respectively. The resonance characteristics of piezoelectric component with leads
51
are, therefore, often deteriorates or experiences large fluctuation in characteristics.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide a piezoelectric component with leads, which prevents a conductive bonding agent such as solder or a conductive adhesive from flowing onto the lead-out electrode or the vibrating electrode, which is therefore resistant to the deterioration of resonance characteristics or filter characteristics, and which minimizes fluctuations in these characteristics.
A piezoelectric component with leads in accordance with preferred embodiments of the present invention includes a piezoelectric plate having first and second main surfaces, a vibrating electrode provided on each of the first and second main surfaces of the piezoelectric plate, a lead-out electrode electrically connected to each of the vibration electrodes on the first and second main surfaces of the piezoelectric plate, first and second terminal electrodes connected to the lead-out electrodes on the first and second main surfaces of the piezoelectric plate, respectively, and each of the first and second terminal electrodes disposed in the vicinity of end portions of the piezoelectric plate, and lead terminals each having lead-out portions continuous with holding portions which are disposed so as to hold the piezoelectric plate at the end portions thereof. In this piezoelectric component with leads, the holding portion of each of the lead terminals is preferably arranged so as not to extend onto the lead-out electrode, and the holding portion of each of the lead terminals is bonded to each of the terminal electrodes.
In accordance with a preferred embodiment of the present invention, where the direction in which the lead terminals extend is the height direction, the height dimension of the holding portion of the lead terminals is preferably not more than the remaining size obtained by subtracting the height dimension of the lead-out electrodes from the height dimension of the piezoelectric plate.
In another preferred embodiment of the present invention, as the above-described vibration electrodes, first and second vibration electrodes are arranged to be opposed to each other with the piezoelectric plate therebetween, whereby a piezoelectric resonator is constructed.
In a piezoelectric component with leads in accordance with preferred embodiments of the present invention, the lead terminals have a plurality of the holding portions. The holding portions have a three-dimensional shape covering at least one of the first and second main surfaces of the piezoelectric plate and an end surface thereof. Preferably, the cross section of the holding portion has a three-dimensional shape such as a substantially U-shaped configuration, a substantially V-shaped configuration, or a substantially L-shaped configuration. More preferably, the holding portion has a substantially L-shaped cross-section.
The above and other elements, characteristics, features and advantages of the present invention will be apparent from the following detailed description of preferred embodiments of the invention in conjunction with the accompanying drawings. Also, it is to be understood that the invention is not limited to the specific preferred embodiments thereof except as defined in the appended claims.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments hereof with reference to the attached drawings.
REFERENCES:
patent: 5369382 (1994-11-01), Arvanitis
patent: 5596244 (1997-01-01), Kugou et al.
patent: 5808397 (1998-09-01), Kotani
patent: 6087763 (2000-07-01), Kim et al.
patent: 6232699 (2001-05-01), Wajima
patent: 6236140 (2001-05-01), Arimura
patent: 54-137995 (1979-10-01), None
patent: 2-326 (1990-01-01), None
patent: 6-58620 (1994-08-01), None
patent: 6-252683 (1994-09-01), None
Kotani Kenichi
Yoshio Masakazu
Dougherty Thomas M.
Keating & Bennett LLP
Murata Manufacturing Co. Ltd
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