JPS62157411A - Characteristic adjusting method for piezoelectric vibrator filter - Google Patents

Abstract

PURPOSE:To easily obtain a desired frequency characteristic by adding an adjusting substance only to the surface of at least one electrode among four electrodes arranged to the front rear main faces of a piezoelectric plate so as not to deteriorate the guarantee attenuation of a filter. CONSTITUTION:The piezoelectric vibrator comprising the piezoelectric plate 1 and electrodes 2, 3 is used as an input terminal and the piezoelectric vibrator comprising electrodes 5, 4 is used as an output terminal, and the electrodes 3, 4 are connected to form a common terminal. Adjusting substances 21, 31, 41 to obtain a desired frequency characteristic are provided only on the surface of the electrodes 2, 3, 4 respectively. A prescribed amount of the adjusting substance is given to the surface only at the required position on the surface of the electrodes 2, 3, 4 while observing the frequency characteristic of the piezoelectric vibrator by means of an oscilloscope or the surface of the electrodes is shaped by a prescribed amount to obtain the desired band frequency characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for adjusting the characteristics of a piezoelectric vibrator used as a frequency band filter in an electronic circuit.

(Prior art) A piezoelectric vibrator is constructed by cutting out a piece of quartz crystal and depositing or painting electrodes on both the front and back surfaces, which are then connected in a ladder configuration and used in an electronic circuit as a frequency band filter. It is being

Figure 3 shows this type of frequency band filter (filter).
FIG. 2 is a cross-sectional view of the configuration of an example, and in this filter, two sets of piezoelectric vibrators are used.

In the figure, 1 is a piezoelectric plate, 2 to 5 are electrodes, and a pair of electrodes 2 and 3, which serve as opposing electrodes, and an electrode 4.5 are arranged on the front and back main surfaces of one piezoelectric plate 1, respectively. They are spaced apart from each other. Then, electrode 3 and electrode 4 are connected and drawn out as a common terminal side, and the input end is connected to electrode 2.3.
In this filter, in which the output end is arranged between electrodes 5 and 4, the electrode 2 at the input end and the electrode 5 at the output end are spaced apart from each other on the front and back through the piezoelectric vibrator l. Therefore, in the equivalent circuit of FIG. 3 shown in FIG. 4, the electrode T111pJ'几/' between electrode 2 and electrode 5
, −Jtdhe+w 1lbTh / Th $
1. % 1 When adjusting the frequency characteristics of the filter, as shown in Figure 3, each electrode 2
A desired frequency characteristic is obtained by attaching an adjusting substance to the surface of 5 to 5 or its side surface, or by scraping a part of the vapor-deposited or painted electrode.

(Problems to be Solved by the Invention) As mentioned above, when adjusting the frequency characteristics of this kind of filter, if an adjusting substance is attached to the electrodes, the distance between the electrodes 2 and 4 as shown in FIG. The distance between the electrodes 5 and 3 becomes narrower due to the addition of the adjusting substance 4 or 3', and the capacitance C21 or capacitance C22 shown in FIG. 4 increases. For this reason, the frequency of the vibrator made up of the piezoelectric plate 1 and the electrode 2.3, and the frequency of the vibrator made up of the electrode 4.5 change greatly, and the coupling coefficient between the mutual vibrators also changes. As a result, the guaranteed attenuation amount of the filter deteriorates, causing a problem that it takes time and effort to obtain desired frequency characteristics.

(Means for Solving the Problems) According to the present invention, two pairs of electrodes are provided on the front and back main surfaces of a piezoelectric plate, and two pairs of electrodes are connected in a diagonal direction when viewed from the cross-sectional direction. In a method for adjusting the characteristics of a piezoelectric vibrator filter in which the input terminal is between one electrode and the opposing electrodes, and the output terminal is between the remaining electrodes, at least one of the four electrodes is A method for adjusting the characteristics of a piezoelectric vibrator filter is provided, which is characterized in that an adjusting substance is applied only to the surface.

(Function) In the present invention, since the adjusting substance is attached only to the surface of the electrodes constituting the piezoelectric vibrator, the increase in interelectrode capacitance between the electrodes on the same main surface is extremely small, and the piezoelectric vibrator There is an effect in which the influence of changes in mutual coupling coefficients can be ignored.

(Example) Next, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a structural sectional view showing an embodiment of the method for adjusting characteristics of a piezoelectric vibrator filter according to the present invention, and the same parts as in FIG.

In FIG. 1, a piezoelectric vibrator made up of a piezoelectric plate l and electrodes 2 and 3 is used as an input terminal, a piezoelectric vibrator made up of electrodes 5 and 4 is used as an output end, and electrodes 3 and 4 are connected. The common terminal side is also similar to that shown in FIG.

Note that the electrode 3 is provided slightly beyond the center line of the piezoelectric plate, that is, the midline between the piezoelectric vibrators at the input end and the output end, and is provided with adjusting substances 21 and 3 to obtain desired frequency characteristics.
1.41 are attached only on the surface of the electrode 2.3.4, respectively.

Moreover, FIG. 2 is a perspective view of this embodiment.

Next, when adjusting the piezoelectric vibrator, for example, a standard signal generator, a frequency sweep oscillator, an oscilloscope, etc. are used, although not shown in the drawings, and are connected so that the frequency characteristics of the piezoelectric vibrator can be directly observed.

Then, while monitoring the frequency ee characteristics with an oscilloscope, a predetermined amount of the adjustment substance is applied to the required positions on the surfaces of the electrodes 2, 3.4, using a mask on the electrodes only. Alternatively, if necessary, the surface of the electrode is scraped off by a predetermined amount 1 using a laser or the like, and adjusted so as to obtain a desired band frequency characteristic.

Although the embodiment of the present invention has been described, various modifications are possible within the scope of the gist of the present invention, and these are not excluded from the scope of the present invention (effects of the invention). Two pairs of opposing electrodes are provided on the front and back main surfaces of the piezoelectric plate, and the two diagonal electrodes are connected when viewed from the cross-sectional direction, and the remaining one electrode and the space between the above opposing electrodes are used as the input end, and the other In the method for adjusting the characteristics of a piezoelectric resonator filter with the output end between the electrodes of However, the change in interelectrode capacitance between electrodes on the same principal surface is very small, and the effect of changes in the coupling coefficient due to attachment is negligible, so the guaranteed attenuation of the filter does not deteriorate and can be easily removed. This has the effect of obtaining desired frequency characteristics.

[Brief explanation of drawings]

@ Figure 1 is a cross-sectional view of a configuration showing an example of the method for adjusting characteristics of a piezoelectric resonator filter according to the present invention, Figure 2 is a perspective view of a piezoelectric resonator filter, and Figure 3 is an example of a conventional frequency band filter. The configuration sectional view and FIG. 4 are its equivalent circuit diagrams. 1... Piezoelectric plate, 2-5... Electrode, 21, 31.41
...Adjustment substance.

Claims (1)

[Claims] Two pairs of opposing electrodes are arranged on the front and back main surfaces of the piezoelectric plate, and the two electrodes in the diagonal direction when viewed from the cross-sectional direction are connected, and the remaining one electrode and the space between the above opposing electrodes are used as the input end, and the other A method for adjusting characteristics of a piezoelectric vibrator filter in which the output end is between the remaining electrodes and the electrode facing the piezoelectric vibrator, characterized in that an adjusting substance is attached only to the surface of at least one of the four electrodes. How to adjust the characteristics of the child filter.