Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2000-12-20
2004-06-01
Budd, Mark (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S340000
Reexamination Certificate
active
06744179
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric resonator and to a piezoelectric oscillator having exterior substrates which are laminated over and under a piezoelectric resonating element, and more particularly, the present invention relates to a piezoelectric resonator and a piezoelectric oscillator for use in, for example, a clock generation oscillator for a microcomputer.
2. Description of the Related Art
In the past, piezoelectric resonators constructed by combining a piezoelectric resonating element with a capacitor and built-in load capacitance type piezoelectric oscillators have been proposed. For example, in Japanese Patent No. 2666295, piezoelectric components shown in
FIGS. 9A and 9B
are disclosed. In a piezoelectric component
101
, exterior substrates
103
and
104
are laminated over and under, respectively, a plate-like piezoelectric resonating element
102
. The piezoelectric resonating element
102
which includes a piezoelectric diaphragm
105
and excitation electrodes
106
and
107
is an energy-trap type piezoelectric resonator. The excitation electrodes
106
and
107
are arranged to face each other via the piezoelectric diaphragm
105
. The excitation electrode
106
is led to one end surface of a laminate body which includes the piezoelectric diaphragm
105
and the exterior substrates
103
and
104
. An external electrode
108
is provided on the end surface. The excitation electrode
107
is led to the other end surface of the laminated body and is electrically connected to an external electrode
109
provided on the other end surface.
The external electrodes
108
and
109
are arranged to cover not only end surfaces of the laminated body but also the top surface, a pair of side surfaces, and the bottom surface thereof. In the middle of the laminated body, an external electrode
110
is wound around the bottom surface, the pair of the side surfaces, and the bottom surface thereof.
In the piezoelectric component
101
, capacitors are provided between the external electrodes
108
and
110
and between the external electrodes
109
and
110
.
The capacitors achieve a high capacitance by using the upper and lower exterior substrates
103
and
104
.
In Japanese Patent No. 2839092, Japanese Unexamined Patent Application Publication No. 4-192709, Japanese Unexamined Utility Model Patent Application No. 5-18120, etc., there are disclosed capped piezoelectric components constructed by bonding the piezoelectric resonating element to a package substrate in which a capacitor is provided thereon and then bonding cap material for enclosing the piezoelectric resonating element.
In these capped piezoelectric components, the package substrate which has the piezoelectric resonating element mounted thereon includes a multilayer substrate. In the multilayer substrate, the capacitor is provided. That is, by providing the capacitor in the package substrate, the piezoelectric component constructed by combining the piezoelectric resonating element with the capacitor is miniaturized.
In the piezoelectric component
101
disclosed in Japanese Patent No. 2666295, capacitors connected to the piezoelectric resonating element
102
are configured by arranging each of the exterior substrates
103
and
104
over and under, respectively, the piezoelectric resonating element
102
. Accordingly, a piezoelectric component having a reduced height is provided.
When a capacitor having high capacitance is desired, ceramic substrates having a high dielectric constant must be used as the exterior substrates
103
and
104
. Such ceramic substrates have a low deflective strength and are difficult to construct as thin walls. Accordingly, each of the exterior substrates
103
and
104
must be thickened to some extent. This prevents the capacitor from having high capacitance.
When a construction is desired in which the exterior substrates
103
and
104
, each of which includes a high dielectric constant ceramic substrate, are laminated over and under, respectively, the piezoelectric resonating element, the laminated body is affixed on an adhesive sheet and then is cut. However, when the laminated body is cut, chipping tends to occur because a high dielectric constant ceramic substrate has reduced workability.
That is, in a construction, such as that of the piezoelectric component
101
in which the exterior substrates
103
and
104
are laminated over and under, respectively, the piezoelectric resonating element
102
, a low dielectric constant dielectric ceramic substrate which has excellent workability must be used as one of the upper and lower exterior substrates
103
and
104
. This prevents the capacitor from having high capacitance.
On the other hand, in the above-described capped piezoelectric component, a cap such as a metal cap is bonded to the top surface of the package substrate. Since the package substrate has a larger planar shape than the cap itself, miniaturization of the piezoelectric component is difficult. In addition, the capacitor cannot be constructed in the cap, and it is constructed exclusively in the package substrate. Therefore, it is difficult to construct the capacitor having high capacitance. Since the capacitor must be constructed exclusively in the package substrate, the dimensions of the package substrate must be increased in this respect as well.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide a piezoelectric resonator having exterior substrates which are laminated over and under a piezoelectric resonating element. The resonator solves the above-described problems such that the resonator is miniaturized and shortened, and a capacitor having high capacitance is achieved.
Further, preferred embodiments of the present invention provide a built-in load capacitance type piezoelectric oscillator in which a three-terminal capacitor is connected to the piezoelectric resonating element that is miniaturized and shortened, so as to provide a capacitor having very high capacitance with no disadvantages.
To this end, according to a first preferred embodiment of the present invention, a piezoelectric resonator includes a piezoelectric resonating element, and a first exterior substrate and a second exterior substrate, laminated over and under, respectively, the piezoelectric resonating element. In the piezoelectric resonator, the first exterior substrate and the second exterior substrate each include a multilayer substrate having at least one layer of an internal electrode.
In the piezoelectric resonator, each of the first exterior substrate and the second exterior substrate have a first internal electrode and a second internal electrode provided via a substrate material layer, and have a capacitor provided therein.
The first exterior substrate and the second exterior substrate each include a pair of a first internal electrode and a second internal electrode provided at the same height level, and a third internal electrode provided with the first and second internal electrodes via a substrate material layer. In the piezoelectric resonator, the capacitors are provided between the first internal electrode and the third internal electrode and between the second internal electrode and the third internal electrode, respectively.
In the piezoelectric resonator, alternatively, the first internal electrode of the first exterior substrate and the first internal electrode of the second exterior substrate are connected to a first electric potential and a second electric potential, respectively, and the second internal electrodes of the first exterior substrate and the second exterior substrate are each grounded.
In the piezoelectric resonator, the first exterior substrate and the second exterior substrate each include a first substrate material layer which is liquid-sintered and a second substrate material layer which is not sintered at the sintering temperature of the first substrate material layer.
According to a second preferred embodiment of the
Kotani Kenichi
Wajima Masaya
Budd Mark
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
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