JPH0332100Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a two-terminal resonator having a structure in which a piezoelectric element is held by a pair of terminal plates, and particularly relates to improvements in the terminal plates.

Conventional technology For example, a rectangular piezoelectric element that uses a spreading vibration mode has a high mechanical Q (hereinafter referred to as Qm), but on the other hand, when a filter is constructed using this piezoelectric element, the amplitude characteristics in the passband are not very good. Furthermore, the group delay time (hereinafter referred to as GDT) is also poor.

Conventionally, in order to improve this problem, an anisotropic conductive rubber was used between the piezoelectric element a and the terminal plate, as shown in Fig. 3.
bc was involved. The appropriate mass of anisotropic conductive rubber lowers Qm and improves amplitude characteristics and GDT.
This is an attempt to improve.

Problems to be Solved by the Invention However, in the conventional structure described above, not only is the anisotropic conductive rubber expensive, but there are also structural problems such as a large number of parts and a large number of man-hours for manufacturing. Ta.

In view of these problems, the present invention provides a two-terminal resonator that has good amplitude characteristics without intervening conductive rubber between the piezoelectric element and the terminal plate, and can realize an excellent GDT filter. It is intended to.

Means for Solving the Problems In order to achieve the above object, the present invention includes a piezoelectric element and a pair of terminal plates having conductive protrusions that are brought into contact with electrode films provided on both main surfaces of the piezoelectric element. In the two-terminal resonator, an elastic insulating protrusion is provided protrudingly on the terminal plate surface at a location corresponding to the vibration node portion of the main surface of the piezoelectric element, and the protrusion is brought into pressure contact with the element surface or the electrode film. It is characterized by holding the piezoelectric element.

Function When the elastic insulating protrusion is pressed against the vibration node portion of the main surface of the piezoelectric element, the pressure applied applies appropriate damping to the piezoelectric element, lowering the resonance resistance and lowering Qm. As a result, it is possible to improve the amplitude characteristics and GDT in the same manner as in the conventional case using anisotropically conductive rubber.

Embodiment FIG. 1 shows a two-terminal resonator as an embodiment of the present invention, in which 1 is a piezoelectric element, and 2 and 3 are terminal plates.

The piezoelectric element 1 is, for example, a square piezoelectric ceramic plate with electrode films formed on both main planes, and uses a spreading vibration mode.

Terminal plates 2 and 3 are main surfaces 1a and 1b of piezoelectric element 1
It is made up of a metal plate that is made up of plate parts 2a, 3a having substantially the same shape as the metal plate, and drawer lead parts 2b, 3b integrally extended from the plate parts. The plate portions 2a, 3a are provided with conductive protrusions 4, 5 protruding from the electrode films provided on the main surfaces 1a, 1b of the piezoelectric element, and nodes (vibration nodes) n1, n2
Resilient insulating protrusions 6...7... are provided at locations corresponding to.... For example, silicone rubber can be suitably used as the projections 6...7.
It is preferable that the heights of the protrusions 6...7 are slightly higher than the conductive protrusions 4, 5. However, since the terminal plates 2 and 3 are pressed against the main surface of the piezoelectric element, the conductive protrusions 4,
The electrical connection between the piezoelectric element 5 and the piezoelectric element 1 is maintained. The shape of the protrusions 6, 7, etc. is arbitrary, such as a conical shape or a cylindrical shape.

The positions at which the protrusions 6...7 are provided are appropriately determined depending on the vibration mode of the piezoelectric element 1. For example, in the case of a piezoelectric element that uses a spreading vibration mode, the nodes n1, n2, etc. are located near the middle of each side as shown in Fig. 2, so the protrusions 6, 7, and so on should be placed at corresponding positions. good. Incidentally, the protrusions 6...7... are attached to the terminal plates 2, 3 with a suitable adhesive.

According to the two-terminal resonator having the above configuration, piezoelectricity can be generated by the elastic protrusions 6...7... provided on the terminal plates 2, 3 without using anisotropically conductive rubber as described in the section of operation. Since the main surface of element 1 is held under pressure,
Qm of the piezoelectric element 1 decreases due to the pressure contact force,
Amplitude characteristics are two important characteristics of filters.
GDT is improved.

Effects of the invention As explained above, according to the two-terminal resonator according to the invention, it is possible to improve amplitude characteristics and characteristics important for a filter such as GDT without using expensive anisotropic conductive rubber, and also to improve characteristics important for filters such as GDT. Since no electrically conductive rubber is required, costs can be reduced, and the number of parts can be reduced, making assembly easier.

In addition, the piezoelectric element is held at multiple points, including elastic insulating protrusions, instead of being supported at one point by conductive protrusions as in the past, which strengthens the piezoelectric element's holding and prevents external shocks. This greatly reduces the risk of the piezoelectric element being tilted or the edges of the piezoelectric element being chipped or cracked, allowing stable use over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a two-terminal resonator as an embodiment of the present invention, FIG. 2 is an exploded view of the resonator,
FIG. 3 is a diagram showing a conventional two-terminal resonator. 1... Piezoelectric element, 1a, 1b... Main surface, 2, 3...
Terminal board, 2a, 3a... plate portion, 4, 5... conductive protrusion, 6, 7... insulating protrusion.

Claims (1)

[Scope of utility model registration request] In a two-terminal resonator comprising a piezoelectric element and a pair of terminal plates having conductive protrusions that are in contact with electrode films provided on both main surfaces of the piezoelectric element, the main surface of the piezoelectric element is on the terminal plate surface. A resilient insulating protrusion is provided at a location corresponding to the vibration node of the
A two-terminal resonator characterized in that a piezoelectric element is held by bringing the protrusion into pressure contact with the main surface of the element or an electrode film.