JPS581563B2 - ceramic ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic resonator, and particularly relates to thickness-shear vibration (thickness-shear vibration) using a rectangular ceramic plate in a low frequency region.
This paper relates to a ceramic resonator using an energy confinement type.

2. Description of the Related Art In recent years, various ceramic resonators and ceramic filters using ceramics have been developed and put into practical use in response to demands for electronic circuits to be smaller, more solid, more stable, and less inductance.

However, in the low frequency region, for example, in the frequency region below 1.5 MHz, resonators using various vibration modes (radial vibration, longitudinal vibration, bending vibration) have been put into practical use, but thickness shear vibration is not used. The resonators that were used have not been put into practical use.

In other words, when trying to realize a resonator using thickness-shear vibration in a low frequency range, the ceramic plate of the resonator becomes thicker and the electrode area becomes larger, resulting in a larger element shape.
This has the disadvantage of generating many spurious waves (unnecessary vibrations), making it difficult to put it into practical use.

The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a ceramic resonator that uses thickness shear vibration in a low frequency region and eliminates the spurious response of the ceramic resonator.

Generally, when manufacturing a ceramic resonator using thickness shear vibration, a square ceramic plate is obtained by cutting a cubic ceramic block to a predetermined thickness.

In other words, since a rectangular shape is the easiest to manufacture,
Ceramic plates of this shape are generally used.

It is known that the most efficient shape for an electrode on a square ceramic plate is a square electrode that has the same shape as the plane of the ceramic plate.

According to this invention, a side W of a rectangular ceramic plate plane is perpendicular to the polarization direction, and an electrode length W in the same direction as the perpendicular side W.
By setting the length ratio w (W≦1.45w), it is possible to obtain a ceramic resonator in which spurious noise due to the thickness of the ceramic plate and spurious noise due to bending vibration are eliminated.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1a is a plan view of a ceramic resonator using thickness-shear vibration according to the present invention, and b is a side view of the ceramic resonator according to the present invention. It is a board.

Then, square electrodes 2 having sides l and w are provided on both sides of the ceramic plate 1, facing each other, and on the ceramic plate.

The length t of the side of this electrode 20 in the polarization direction is determined by the desired resonance frequency, and the length L of one side of the ceramic plate 1
takes a larger value than the length t of the electrode 2.

and a side W perpendicular to the polarization direction P of the ceramic plate 10,
By appropriately selecting the ratio of the length to the electrode length W in the same direction, spurious noise near the resonance frequency can be removed.

That is, the thickness (H) x width (L) x length (W) is 1.0mm x 12. In a resonator with a ceramic plate of Omm x 3.6 mm and a resonant frequency of approximately IMHz, the frequency-admittance characteristic of this resonator can be adjusted by selecting the electrode size according to the relationship W = 0.96w to W = 1.5w. has the characteristics as shown in FIGS. 2 to 6.

Figure 2 shows the frequency-admittance characteristic when W = 0.96w, and the resonance frequency fm and anti-resonance frequency f
n, respectively.

However, some spurious components 21 exist in a frequency band lower than the resonance frequency fm.

Further, spurious 22 also exists between the resonant frequency fm and the anti-resonant frequency fn.

FIG. 3 is a characteristic diagram when W=1.02w, and compared to FIG. 2, spurious noise around the resonance frequency fm is removed, and the characteristics are good.

Furthermore, Fig. 4 and Fig. 5 are characteristic diagrams when W = 1.2w and W = 1.45w, and compared to Fig. 2, the spurious around the resonance frequency fm is removed and the characteristics are good. are doing.

Figure 6 is a characteristic diagram when W = 1.5w, in which spurious 61 exists in a frequency band lower than the resonant frequency fm, and large spurious 62 occurs in a frequency band higher than the anti-resonant frequency fn. .

That is, the spurious waves 21 and 22 in FIG. 2 or the spurious waves 61 and 62 in FIG. 6 can be removed by changing the length W of the electrode in the direction perpendicular to the polarization direction of the ceramic plate and the length W of the ceramic plate. It can be seen from the above that these spurious signals are caused by bending vibration.

Therefore, in order to eliminate spurious waves, it is necessary to have an element shape that has weak coupling with bending vibration and strongly excites thickness shear vibration.

From the above, it can be seen that by setting the electrode length W in the same direction as the side W perpendicular to the polarization direction of the ceramic plate 10 to W)w or W≦1.45w, it is possible to obtain good characteristics without spurious. .

Therefore, by setting W)w or W(1.45w, as is clear from the figure, the frequency -
It becomes an admit characteristic.

Although the above description assumes that the resonant frequency fm is approximately IMHz, the desired resonant frequency fm can be arbitrarily selected within the low frequency region.

Furthermore, since this resonator is of an energy confinement type, the portion of the ceramic plate 1 where the electrodes 2 are not installed can be fixed with resin or the like, thereby reducing failures due to support of the resonator.

As explained above, according to the present invention, there is provided a square ceramic plate polarized in a direction perpendicular to the plate thickness direction, and a ceramic plate provided at a predetermined position on an opposite plane perpendicular to the plate thickness direction of the ceramic plate. In a ceramic resonator using thickness shear vibration, the electrodes are arranged in the same direction as the length W of the side perpendicular to the polarization direction of the ceramic plate plane. It is possible to obtain a ceramic resonator characterized in that the length W is formed in a relationship such that w (W≦1.45w).

Therefore, it is possible to obtain a ceramic resonator that uses thickness shear vibration, has a resonant frequency in a low frequency region, and eliminates spurious signals near the resonant frequency.

That is, a ceramic resonator using thickness shear vibration can be put to practical use in a low frequency region.

Furthermore, since the ceramic resonator using thickness shear vibration can support and fix the portion where no electrode is installed, the element can be supported reliably, which has the effect of reducing failures due to support.

[Brief explanation of drawings]

Figures 1a and 1b are diagrams for explaining the ceramic resonator according to the present invention, in which a is a plan view and b is a side view of one side, and Figures 2 to 6 are views showing the side W of the ceramic plate and the side W of the electrode. It is a frequency-admittance characteristic diagram when the ratio of is arbitrarily changed. 1... Ceramic plate, 2... Electrode.

Claims (1)

[Claims] 1 A rectangular ceramic plate polarized in a direction perpendicular to the plate thickness direction, and a ceramic plate provided at a predetermined position on each opposing plane perpendicular to the plate thickness direction and parallel to each side forming this plane. In a ceramic resonator using thickness shear vibration, which is equipped with a pair of rectangular electrodes having sides, the length W of the side perpendicular to the polarization direction of the ceramic plate plane and the electrode length W in the same direction are W< W≦L45w
A ceramic resonator characterized by being formed in the following relationship.