JP7215201B2 - Frequency adjustment method and frequency adjustment device for piezoelectric vibration filter - Google Patents

Description

The present invention relates to a frequency adjustment method and a frequency adjustment device for a piezoelectric vibration filter.

Piezoelectric vibration filters such as MCFs (Monolithic Crystal Filters) are used as frequency selection means, for example, in small handheld communication devices. FIG. 1 is a side view showing a general configuration of a piezoelectric vibration filter 100. FIG.

In the piezoelectric vibration filter 100, a common electrode 102 is formed on one main surface S1 of a piezoelectric diaphragm 101, and an input electrode 103 and an output electrode 104 are formed side by side with a gap G on the other main surface S2. The common electrode 102 is formed so as to face the input electrode 103, the output electrode 104 and all the formation regions of the gap G. As shown in FIG. Further, each electrode film of the common electrode 102, the input electrode 103 and the output electrode 104 has a structure in which, for example, chromium is used as a base metal and silver is vapor-deposited thereon.

The frequency characteristics of the piezoelectric vibration filter 100 shown in FIG. 1 are the symmetrical mode (symmetrical wave of thickness shear) shown in FIG. Determined by interactions. In FIG. 2 , the vertical axis indicates the displacement strength, and the horizontal axis indicates the distance from a certain point on the surface of the piezoelectric vibration filter 100 .

The size, film thickness, arrangement, etc. of each electrode film in the piezoelectric vibration filter 100 are designed so that the piezoelectric vibration filter 100 has desired frequency characteristics (that is, frequency characteristics that meet product standards). However, in reality, it is rare that desired frequency characteristics can be obtained only by forming an electrode film. Is required. Such frequency adjustment can be achieved by a method of increasing the thickness (film addition) of the electrode film in a predetermined area by a method such as partial vapor deposition (so-called partial adjustment), or by irradiating an ion beam on the electrode film in a predetermined area. It is performed by a method (so-called ion partial adjustment) of reducing the film thickness (film removal) by a method such as.

As the frequency adjustment of the piezoelectric vibration filter 100,
・Balance adjustment ・Band adjustment (Fs adjustment, Fa adjustment)
- Three kinds of processes of full surface adjustment are performed in this order (for example, patent document 1). Each of these steps is selectively performed according to the frequency characteristics of the piezoelectric vibration filter 100 at that time, and some steps may be omitted when adjustment is unnecessary. FIG. 3 is a diagram showing each step of frequency adjustment by partial adjustment, (a) showing balance adjustment, (b) Fs adjustment, (c) Fa adjustment, and (d) overall adjustment. FIG. 4 is a diagram showing each step of frequency adjustment by ion partial adjustment, in which (a) shows balance adjustment, (b) Fs adjustment, (c) Fa adjustment, and (d) full adjustment. ing. In FIG. 3, the portion where the film thickness is increased by the partial adjustment is indicated by oblique hatching, and in FIG. 4, the portion where the film thickness is reduced by the ion partial adjustment is indicated by projection hatching.

Balance adjustment is performed by adjusting the resonance frequency F1 in the first resonance region where the input electrode 103 and the common electrode 102 face each other and the resonance frequency F2 in the second resonance region where the output electrode 104 and the common electrode 102 face each other. This is a step of matching. Specifically, in the balance adjustment, the thickness of the common electrode 102 in either one of the first resonance region and the second resonance region is relatively increased or decreased to match the resonance frequency F1 and the resonance frequency F2. Let For example, when F1 < F2, the film thickness of the common electrode 102 in the second resonance region is increased in the partial adjustment (see FIG. 3A), and the film thickness of the common electrode 102 in the first resonance region is increased in the ion partial adjustment. decrease (see FIG. 4(a)). Conversely, when F1 > F2, the film thickness of the common electrode 102 in the first resonance region is increased in the partial adjustment, and the film thickness of the common electrode 102 in the second resonance region is decreased in the ion partial adjustment.

The band adjustment adjusts the passband width of the piezoelectric vibration filter, and is a process of widening or narrowing the bands of the symmetrical mode and the obliquely symmetrical mode. Note that the band adjustment includes Fs adjustment that mainly changes the vibration frequency Fs of the symmetric mode and Fa adjustment that mainly changes the vibration frequency Fa of the oblique symmetric mode, one of which has the effect of widening the passband width. , and the other have the effect of narrowing the passband width. In the Fs adjustment, the film thickness of the common electrode 102 in the region facing the gap G is increased or decreased. On the other hand, the Fa adjustment increases or decreases the film thickness of the common electrode 102 in the first resonance region and the second resonance region.

When trying to widen the passband width in band adjustment, the film thickness of the common electrode 102 in the area facing the gap G is increased relatively more than in other areas. When the adjustment for widening the passband width is performed by partial adjustment, Fs adjustment is performed. That is, in Fs adjustment by partial adjustment, the passband width is widened by increasing the film thickness of the common electrode 102 in the region facing the gap G (see FIG. 3B). On the other hand, Fa adjustment is performed when the ion partial adjustment is used to widen the passband width. That is, in Fa adjustment by ion partial adjustment, the passband width is widened by reducing the film thickness of the common electrode 102 of the first resonance region and the second resonance region (see FIG. 4B).

When trying to narrow the passband width in the band adjustment, the film thickness of the common electrode 102 in the region facing the gap G is relatively reduced as compared with the other portions. Fa adjustment is performed when the adjustment for narrowing the passband width is performed by partial adjustment. That is, in Fa adjustment by partial adjustment, the passband width is narrowed by increasing the film thickness of the common electrode 102 of the first resonance region and the second resonance region (see FIG. 3(c)). On the other hand, when the ion partial adjustment is used to narrow the passband width, the Fs adjustment is performed. That is, in Fs adjustment by ion partial adjustment, the passband width is narrowed by reducing the film thickness of the common electrode 102 in the region facing the gap G (see FIG. 4(c)).

The overall adjustment is a process of adjusting the center frequency of the piezoelectric vibration filter, and by increasing or decreasing the thickness of the common electrode 102 as a whole, only the center frequency is adjusted without changing the passband width. is performed. That is, the partial adjustment increases the thickness of the common electrode 102 as a whole (see FIG. 3D), and the ion partial adjustment decreases the thickness of the common electrode 102 as a whole (see FIG. 4D). .

Incidentally, Patent Document 1 discloses frequency adjustment for a two-pole piezoelectric vibration filter, while Patent Document 2 discloses frequency adjustment for a three-pole piezoelectric vibration filter.

Japanese Patent No. 3965681 Japanese Patent No. 3468160

In the conventional frequency adjustment, there is a problem that the number of processes required to obtain desired frequency characteristics for one piezoelectric vibration filter increases, and the frequency adjustment takes a long time. This is especially due to the repeated need for Fs and Fa adjustments in band adjustment. For example, when Fs adjustment is performed, not only the vibration frequency Fs of the symmetrical mode but also the vibrational frequency Fa of the oblique symmetrical mode are changed at the same time. Similarly, when Fa adjustment is performed, not only the vibration frequency Fa but also the vibration frequency Fs are changed at the same time.

For this reason, conventionally, it was difficult to know the appropriate amount of adjustment when performing Fs adjustment and Fa adjustment, and fine adjustments were often repeatedly performed until desired frequency characteristics were obtained. In addition, as the Fs adjustment and the Fa adjustment are repeatedly performed, the frequencies of the resonance frequency F1 and the resonance frequency F2 are different, and there are cases where rebalance adjustment is required. Furthermore, even if the above adjustment is repeated, the desired frequency characteristic cannot be obtained, and there is also a problem of a decrease in yield due to adjustment errors.

The present invention has been made in view of the above problems, and by predicting the amount of adjustment, it is possible to significantly reduce the number of repetitions of the adjustment process in frequency adjustment of a piezoelectric vibration filter, shorten the time required for frequency adjustment, and adjust the frequency. The purpose is to improve accuracy and yield.

In order to solve the above problems, a frequency adjustment method according to a first aspect of the present invention adjusts the frequency characteristics of each piezoelectric vibration filter for a plurality of piezoelectric vibration filters manufactured according to the same product standard. The frequency adjustment method for a piezoelectric vibration filter according to (1), wherein, for one piezoelectric vibration filter, adjustment to widen the passband width of the piezoelectric vibration filter and adjustment to narrow the passband width of the piezoelectric vibration filter are performed. At least a band adjustment for adjusting a passband width is included, and after the frequency adjustment including the band adjustment is performed on at least one piezoelectric vibration filter, frequency adjustment is performed on the other piezoelectric vibration filters. is performed, from the adjustment log of at least one piezoelectric vibration filter whose frequency characteristics have been adjusted, a predicted value that can be used for setting the adjustment amount in the band adjustment is calculated, and after the predicted value is calculated For another piezoelectric vibration filter whose frequency characteristics are to be adjusted, an optimum adjustment amount in the band adjustment is calculated based on the predicted value, and the band adjustment is performed with the calculated adjustment amount. .

According to the above configuration, frequency adjustment is performed for a product group of piezoelectric vibration filters having the same product standard (that is, having the same basic design such as the size, arrangement, and film thickness of each electrode film). Then, a predicted value is calculated from the adjustment log of the piezoelectric vibration filter whose frequency has been adjusted first, and an appropriate adjustment amount is set based on this predicted value for the piezoelectric vibration filter whose frequency is adjusted later. be able to. As a result, in the piezoelectric vibration filter in which the adjustment amount is set based on the predicted value, the number of repetitions in band adjustment can be greatly reduced, and the time required for frequency adjustment can be shortened. In addition, by setting the adjustment amount based on the predicted value, the adjustment accuracy can be improved, and adjustment errors can be reduced, thereby improving the yield.

Further, in the above frequency adjustment method, the predicted value calculated from the adjustment log of the piezoelectric vibration filter whose frequency characteristics have been adjusted is calculated as an average value for a plurality of piezoelectric vibration filters. Each time frequency adjustment to the vibration filter is completed, the value may be updated by adding the result of the adjustment.

According to the above configuration, the accuracy of prediction can be improved as the number of piezoelectric vibration filters subjected to frequency adjustment increases.

Further, in the frequency adjustment method, the piezoelectric vibration filter is a two-pole or four-pole piezoelectric vibration filter, and the band adjustment includes Fs adjustment for adjusting the band of the symmetrical mode and adjusting the band of the oblique symmetrical mode. The predicted value is the ratio of the frequency change amount ΔFa in the oblique symmetric mode to the frequency change amount ΔFs in the symmetric mode when the Fs adjustment is performed (ΔFa/ΔFs), and the Fa adjustment. The ratio of the frequency variation ΔFs in the symmetrical mode to the frequency variation ΔFa in the oblique symmetrical mode (ΔFs/ΔFa)” can be used.

Further, in the frequency adjustment method, the piezoelectric vibration filter is a three-pole piezoelectric vibration filter, and the band adjustment includes Fs1 adjustment for adjusting the band of the first symmetrical mode and adjusting the band of the second symmetrical mode. The predicted value is the ratio of the frequency change amount ΔFs2 in the second symmetric mode to the frequency change amount ΔFs1 in the first symmetric mode when Fs1 adjustment is performed (ΔFs2/ΔFs1), and The ratio of the frequency change amount ΔFs1 in the first symmetric mode to the frequency change amount ΔFs2 in the second symmetric mode when the Fs2 adjustment is performed (ΔFs1/ΔFs2)”.

Further, in order to solve the above problems, a frequency adjustment device according to a second aspect of the present invention is a frequency adjustment device for a piezoelectric vibration filter for adjusting frequency characteristics of each piezoelectric vibration filter, wherein the frequency The adjustment device can perform at least band adjustment for adjusting the passband width of one piezoelectric vibration filter by adjusting the passband width of the piezoelectric vibration filter to widen and adjusting the passband width of the piezoelectric vibration filter to narrow it. a calculation unit that calculates a predicted value that can be used for setting an adjustment amount in the band adjustment from an adjustment log of at least one piezoelectric vibration filter whose frequency characteristics have been adjusted; and a display section for displaying the predicted value.

According to the above configuration, the predicted value calculated by the calculation unit is displayed, so that the user can set and input the optimum adjustment amount based on this predicted value. Thereby, the frequency adjustment method described above can be realized.

Further, in the frequency adjustment device, the calculation unit calculates the predicted value each time the frequency characteristic is adjusted for one piezoelectric vibration filter, and calculates the predicted value for the one piezoelectric vibration filter. The predicted value is compared with the predicted value obtained from the adjustment log of the piezoelectric vibration filter whose frequency characteristics have been previously adjusted, and whether or not the ratio or difference in the comparison is equal to or greater than a predetermined value. If the ratio or difference is equal to or greater than a predetermined value, a warning can be issued.

According to the above configuration, when a piezoelectric vibration filter group having a significantly different predicted value for each palette is generated due to, for example, mask misalignment, the palette can be quickly determined and a warning can be issued. As a result, it is possible to prevent adjustments from being made based on inappropriate predicted values.

Further, in the frequency adjustment device, the piezoelectric vibration filter is a two-pole or four-pole piezoelectric vibration filter, and the band adjustment includes Fs adjustment for adjusting the band of the symmetrical mode and Fs adjustment for adjusting the band of the oblique symmetrical mode. The predicted value is the ratio (ΔFa/ΔFs) of the frequency change amount ΔFa in the oblique symmetric mode to the frequency change amount ΔFs in the symmetric mode when the Fs adjustment is performed, and the Fa adjustment. The ratio of the frequency variation ΔFs in the symmetrical mode to the frequency variation ΔFa in the oblique symmetrical mode (ΔFs/ΔFa)” can be used.

Further, in the frequency adjustment device, the piezoelectric vibration filter is a three-pole piezoelectric vibration filter, and the band adjustment includes Fs1 adjustment for adjusting the band of the first symmetrical mode and adjusting the band of the second symmetrical mode. The predicted value is the ratio of the frequency change amount ΔFs2 in the second symmetric mode to the frequency change amount ΔFs1 in the first symmetric mode when Fs1 adjustment is performed (ΔFs2/ΔFs1), and The ratio of the frequency change amount ΔFs1 in the first symmetric mode to the frequency change amount ΔFs2 in the second symmetric mode when Fs2 adjustment is performed (ΔFs1/ΔFs2)”.

The frequency adjustment method and frequency adjustment device for a piezoelectric vibration filter according to the present invention provide a piezoelectric vibration filter whose frequency has been previously adjusted when frequency adjustment is performed on a product group of piezoelectric vibration filters having the same product standard. By calculating the predicted value from the adjustment log and setting the appropriate adjustment amount based on this predicted value for the piezoelectric vibration filter whose frequency is adjusted later, the number of iterations in band adjustment can be greatly reduced. , the time required for frequency adjustment can be shortened.

FIG. 2 is a side view showing a general configuration of a two-pole piezoelectric vibration filter; It is a graph which shows the vibration mode of the piezoelectric vibration filter of two poles, (a) has shown the symmetrical mode, (b) has shown the diagonally symmetrical mode. It is a figure which shows each process of the frequency adjustment by partial adjustment, (a) shows balance adjustment, (b) Fs adjustment, (c) Fa adjustment, (d) shows full adjustment. It is a figure which shows each process of the frequency adjustment by ion partial adjustment, (a) shows balance adjustment, (b) Fs adjustment, (c) Fa adjustment, (d) shows full adjustment. 1, showing an embodiment of the present invention, is a block diagram showing a schematic configuration of a frequency adjustment device. FIG. FIG. 4 is a diagram conceptually showing changes in oscillation frequency Fs and oscillation frequency Fa when band adjustment is performed by ion partial adjustment, (a) when Fs adjustment is performed, and (b) when Fa adjustment is performed. is shown. It is a figure which shows the example of a display of a frequency adjusting device. FIG. 3 is a side view showing a general configuration of a three-pole piezoelectric vibration filter; It is a graph which shows the vibration mode of the piezoelectric vibration filter of three poles, (a) is a 1st symmetrical mode, (b) is a diagonally symmetrical mode, (c) has shown the 2nd symmetrical mode.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention relates to frequency adjustment of a piezoelectric vibration filter, and the basic structure of the piezoelectric vibration filter according to this embodiment may be the same as that shown in FIG. Further, the frequency adjustment of the piezoelectric vibration filter is performed by the three steps of balance adjustment, band adjustment (Fs adjustment, Fa adjustment) and overall adjustment described with reference to FIGS. 3 and 4, as in the conventional case.

The frequency adjustment method according to the present embodiment predicts the adjustment amount in the band adjustment, thereby significantly reducing the number of repetitions of the process compared to the conventional method, shortening the time required for frequency adjustment, improving the adjustment accuracy, and increasing the yield. It is possible to improve the Note that the frequency adjustment at this time may be performed by either the partial adjustment or the ion partial adjustment described above.

First, a schematic configuration of the frequency adjustment device 10 according to the present embodiment will be described with reference to FIG. The frequency adjustment device 10 includes an adjustment processing section 11 , a control section 12 , a storage section 13 , a display section 14 and an input section 15 .

The adjustment processing unit 11 is means for adjusting the frequency of the piezoelectric vibration filter by partial adjustment or ion partial adjustment. That is, the adjustment processing unit 11 performs partial vapor deposition or ion beam irradiation on the piezoelectric vibration filter using a mask jig to increase or decrease the film thickness of a predetermined region of the common electrode of the piezoelectric vibration filter. The adjustment rate and adjustment time in the adjustment processing section 11 are controlled by the control section 12 .

The storage unit 13 is means for storing an adjustment log of the piezoelectric vibration filter subjected to frequency adjustment by the adjustment processing unit 11 and the like. Specifically, for each piezoelectric vibration filter, a history of adjustment rate, adjustment time, and the like in each step of balance adjustment, band adjustment (Fs adjustment, Fa adjustment), and overall adjustment is recorded as an adjustment log.

The display unit 14 displays the current frequency characteristic (measured value) of the piezoelectric vibration filter set in the adjustment processing unit 11, the current processing condition (set adjustment rate) in the adjustment processing unit 11, and the band adjustment (Fs adjustment, Fa adjustment), and the like, are displayed. This prediction is performed by the control unit 12 based on the adjustment log of the piezoelectric vibration filter whose frequency has already been adjusted, and the details will be described later.

The input unit 15 is means for the user to input the adjustment amount of the frequency adjustment performed by the adjustment processing unit 11 . In the frequency adjustment device 10, the user can refer to the prediction result of the adjustment amount displayed on the display unit, particularly when inputting the adjustment amount when performing band adjustment.

Next, prediction of adjustment amount at the time of band adjustment, which is a feature of frequency adjustment according to the present embodiment, will be described.

As described above, the band adjustment adjusts the passband width of the piezoelectric vibration filter, and is a process of widening or narrowing the bands of the symmetrical mode and the obliquely symmetrical mode.

For the piezoelectric vibration filter to be band-adjusted, the vibration frequency Fs in the symmetrical mode and the vibrational frequency Fa in the oblique symmetrical mode are first measured. The vibration frequency Fs and the vibration frequency Fa can be measured by probe contacting the input electrode and the output electrode of the piezoelectric vibration filter set in the adjustment processing unit 11 . Ordinarily, the vibration frequency Fa of the oblique symmetrical mode is higher than the vibrational frequency Fs of the symmetrical mode, and (Fa-Fs) is the passband width of the piezoelectric vibration filter. The measured vibration frequency Fs and vibration frequency Fa are displayed on the display unit 14 . Further, based on the measured vibration frequency Fs and vibration frequency Fa, the passband width (Fa-Fs) at that time is calculated by the control unit 12, and the calculated passband width (Fa-Fs) is also displayed on the display unit 14. is displayed along with

There is a target value (target passband width) Fr of the passband width when adjusting the band of the piezoelectric vibration filter. That is, in the band adjustment of the piezoelectric vibration filter, the passband width (Fa-Fs) is adjusted to the target passband width Fr. Specifically, when the passband width (Fa-Fs) is wider than the target passband width Fr, it is necessary to narrow the passband width, Fa adjustment is performed in the partial adjustment, and Fs adjustment is performed in the ion partial adjustment. done. Conversely, when the passband width (Fa-Fs) is narrower than the target passband width Fr, it is necessary to widen the passband width, Fs adjustment is performed in the partial adjustment, and Fa adjustment is performed in the ion partial adjustment. . In addition, in the frequency adjustment device 10, the target passband width Fr may be displayed on the display unit 14 as well.

When performing this Fs adjustment or Fa adjustment, the user determines the adjustment amount based on the passband width (Fa-Fs) displayed on the display unit 14 and the target passband width Fr, and inputs the adjustment amount. Input from part 15. The control unit 12 controls the adjustment processing unit 11 based on the input adjustment amount, and performs band adjustment (Fs adjustment or Fa adjustment) on the piezoelectric vibration filter. For example, if the band adjustment to be performed is the Fs adjustment, the user inputs the adjustment amount of the vibration frequency Fs. Based on the set adjustment rate, the control unit 12 calculates an adjustment time such that the amount of change in the vibration frequency Fs is equal to the input adjustment amount, and the adjustment processing unit 11 performs processing for the calculated adjustment time. to do it.

In the band adjustment (Fs adjustment in this example) at this time, the vibration frequency Fs changes by the amount of adjustment input by the user. However, the Fs adjustment mainly changes the vibration frequency Fs, but actually changes the vibration frequency Fa at the same time. Therefore, the passband width (Fa-Fs) cannot be matched with the target passband width Fr by simply inputting the difference between the passband width (Fa-Fs) and the target passband width Fr as it is as an adjustment amount. .

FIG. 6A is a diagram conceptually showing changes in the vibration frequency Fs and the vibration frequency Fa when Fs adjustment is performed by ion partial adjustment. In the waveform shown in FIG. 6(a), two peaks indicate vibration frequencies Fs and Fa, respectively. As described above, the Fs adjustment mainly changes the vibration frequency Fs, and FIG. 6A shows the amount of change in the vibration frequency Fs due to the Fs adjustment as ΔFs. Further, in the Fs adjustment, not only the vibration frequency Fs but also the vibration frequency Fa changes. In FIG. 6A, the amount of change in the vibration frequency Fa due to the Fs adjustment is shown as ΔFa.

FIG. 6B is a diagram conceptually showing changes in the vibration frequency Fs and the vibration frequency Fa when Fa adjustment is performed by ion partial adjustment. In the waveform shown in FIG. 6(b), two peaks indicate vibration frequencies Fs and Fa, respectively. As in the Fs adjustment, the Fa adjustment changes not only the vibration frequency Fa but also the vibration frequency Fs.

In the Fs adjustment, the change amount ΔFs of the vibration frequency Fs changes so as to match the adjustment amount input by the user. However, at this time, since the vibration frequency Fa also changes by the amount of change ΔFa, the amount of change in the passband width (Fa−Fs) does not match the amount of adjustment input by the user, and the amount of change in the vibration frequency Fa changes by the amount ΔFa. lose sight. Therefore, when adjusting Fs, the user needs to set the adjustment amount in anticipation of the amount of change ΔFa in the vibration frequency Fa. Similarly, when adjusting Fa, the user needs to set the adjustment amount in anticipation of the amount of change ΔFs in the vibration frequency Fs.

However, the ratio of the amount of change ΔFa to the amount of change ΔFs during Fs adjustment (ΔFa/ΔFs) and the ratio of the amount of change ΔFs to the amount of change ΔFa during Fa adjustment (ΔFs/ΔFa) depend on the piezoelectric vibration filter undergoing band adjustment. The size, arrangement, and film thickness of each electrode film, in other words, greatly differ depending on the product standard of the piezoelectric vibration filter, and it has been difficult to set an accurate adjustment amount in the piezoelectric vibration filter. For this reason, conventionally, an adjustment value is input based on the user's intuition, and Fs adjustment and Fa adjustment (and, in some cases, balance adjustment) are performed until the passband width (Fa-Fs) matches the target passband width Fr. It was necessary to repeat the fine adjustment by

On the other hand, the frequency adjustment according to the present embodiment is applied to a product group of piezoelectric vibration filters having the same product standard (that is, having the same basic design such as the size, arrangement and film thickness of each electrode film). It is implemented by In piezoelectric vibration filters having the same product standard, the ratio (ΔFa/ΔFs) and the ratio (ΔFs/ΔFa) are considered to be substantially the same in all piezoelectric vibration filters. Therefore, after performing band adjustment on at least one (preferably about 10) piezoelectric vibration filters, the ratio (ΔFa/ΔFs) and the ratio (ΔFs/ΔFa) can be predicted from the adjustment log. can. Frequency adjustment device 10 according to the present embodiment has a function of displaying the ratio (ΔFa/ΔFs) and the predicted value of the ratio (ΔFs/ΔFa) on display unit 14 . The user can refer to this predicted value displayed on the display unit 14 to set an appropriate adjustment amount. As a result, in the piezoelectric vibration filter in which the adjustment amount is set based on the predicted value, the number of repetitions in band adjustment can be greatly reduced, and the time required for frequency adjustment can be shortened. In addition, by setting the adjustment amount based on the predicted value, the adjustment accuracy can be improved, and adjustment errors can be reduced, thereby improving the yield.

FIG. 7 is a diagram showing a specific example of display on the display unit 14 of the frequency adjustment device 10. As shown in FIG. In this example, display is performed in four display areas A1 to A4. The display area A1 displays the target center frequency and the target passband width of the piezoelectric vibration filter whose frequency is to be adjusted. Here, the target center frequency is 44.900000 MHz and the target passband width is 14.000 kHz.

Each measurement value for the piezoelectric vibration filter currently set in the adjustment processing unit 11 is displayed in the display area A2. where "F0" is the current center frequency, "dF0" is the rate of deviation of the current center frequency from the target center frequency, "Fs" is the current symmetric mode vibration frequency Fs, and "Fa ” is the current symmetric mode vibration frequency Fa, “Bw” is the current passband width (Fa−Fs), and “Balance” is the frequency difference between the current resonance frequency F1 and resonance frequency F2.

The adjustment rate set by the adjustment processing section 11 is displayed in the display area A3. Here, "Fs" is the adjustment rate for Fs adjustment, "Fa" is the adjustment rate for Fa adjustment, and "F1" is the adjustment rate for changing the resonance frequency F1 in balance adjustment. where "F2" is the adjustment rate for changing the resonance frequency F2 in balance adjustment, and "F0" is the adjustment rate for overall adjustment. For each adjustment rate, the actual rate is the currently set adjustment rate, the average value is the average adjustment rate for the piezoelectric vibration filters that have undergone frequency adjustment so far, and the maximum value is the frequency adjustment that has been performed so far. Fig. 10 shows the maximum tuning rate for the piezoelectric oscillatory filter that was applied. In the frequency adjustment device 10 according to the present embodiment, since the adjustment log of frequency adjustments performed so far is stored in the storage unit 13, the average value and the maximum value can be obtained based on this adjustment log. can be done.

In the display area A4, a predicted value calculated based on the adjustment log of frequency adjustments performed so far is displayed. Here, "Fa/Fs" is a predicted value of the ratio (ΔFa/ΔFs) of the amount of change ΔFa to the amount of change ΔFs during Fs adjustment, and "Fs/Fa" is the amount of change ΔFs for the amount of change ΔFa during adjustment of Fa. is a predicted value of the ratio (ΔFs/ΔFa) of Note that the predicted value of the ratio (ΔFa/ΔFs) and the predicted value of the ratio (ΔFs/ΔFa) actually change somewhat according to the adjustment rate. In other words, the display area A4 shows the predicted value (actual rate) corresponding to the actual rate (currently set adjustment rate), the predicted value (average value) corresponding to the average adjustment rate, and the maximum adjustment rate. The predicted value (maximum value) for each is displayed. Also, in calculating the average and maximum values, maladjusted or poorly adjusted filter elements are excluded.

When band adjustment is performed in the frequency adjustment device 10, the user can set and input the amount of adjustment from the display result of FIG. 7 as follows. First, since the current passband width (Fa-Fs) is 11.132 kHz from "Bw" and the target passband width is 14.000 kHz, it is necessary to widen the passband width by 2.868 kHz. In the case of ion partial adjustment, Fa adjustment is the process for widening the passband width.

Here, it can be seen that the ratio of the amount of change ΔFs to the amount of change ΔFa during Fa adjustment (ΔFs/ΔFa) is 93% from "Fs/Fa" in the display area A4. That is, when the user inputs an adjustment amount for Fa adjustment, the passband width of the piezoelectric vibration filter is expanded by only 7% (=100-93) of the input adjustment amount. Therefore, the user should input the value (40.957 kHz) obtained by dividing the value (that is, 2.868 kHz) for widening the passband width by 0.07 as the adjustment amount for Fa adjustment. Of course, the amount of adjustment based on the predicted value can also be calculated by the control unit 12 and displayed on the display unit 14 .

In the frequency adjustment method described above, the predicted value displayed in the display area A4 of the frequency adjustment device 10 can be calculated after performing frequency adjustment on at least one piezoelectric vibration filter. It is not particularly limited whether to display at the appropriate timing.

For example, for a product group of piezoelectric vibration filters having the same product standard, the first n (for example, 10) piezoelectric vibration filters are frequency-adjusted without using a predicted value in the same manner as before, and the adjustment log is You may calculate a predicted value from. After that, frequency adjustment using the predicted value can be performed from the (n+1)-th piezoelectric vibration filter.

Alternatively, it is also possible to adjust the frequency of only the first piezoelectric vibration filter without using the predicted value as in the conventional case, and perform the frequency adjustment using the predicted value from the second piezoelectric vibration filter. In this case, the predicted value is calculated as an average value for all the piezoelectric vibration filters whose frequencies have been previously adjusted. preferably updated. As a result, frequency adjustment using the predicted value can be performed from the second piezoelectric vibration filter, and the accuracy of prediction improves as the number of piezoelectric vibration filters subjected to frequency adjustment increases.

Further, the control unit 12 in the frequency adjustment device 10 calculates the ratio (ΔFa/ΔFs) and the ratio (ΔFs/ΔFa) from the adjustment log each time the frequency characteristic is adjusted for one piezoelectric vibration filter. , this calculated ratio (ΔFa/ΔFs) and ratio (ΔFs/ΔFa) are compared to the ratio (ΔFa/ΔFs) and ratio (ΔFs/ΔFa ), and if the ratio or difference is greater than or equal to a predetermined value, a warning may be issued. This warning may be, for example, a warning display on the display unit 14, or may be a warning by an alarm sound or voice message.

That is, even if the piezoelectric vibration filters are manufactured according to the same product standard. For example, it is possible that the ratio (ΔFa/ΔFs) and ratio (ΔFs/ΔFa) differ greatly from those of other filters in palette units due to mask misalignment. By promptly determining a pallet with such a large difference in ratio (ΔFa/ΔFs) and ratio (ΔFs/ΔFa) and issuing a warning, it is possible to prevent adjustment based on an inappropriate predicted value.

Further, in the above description, the case where frequency adjustment is performed for a two-pole piezoelectric vibration filter has been exemplified. The two-pole piezoelectric vibration filter has a configuration in which one common electrode is formed on one surface of one piezoelectric diaphragm, and two electrodes, that is, an input electrode and an output electrode, are formed on the other surface. becomes. However, the piezoelectric vibration filter may have a 3-pole or 4-pole configuration in addition to the 2-pole configuration, and the frequency adjustment method of the present invention can also be applied to a 3-pole or 4-pole piezoelectric vibration filter.

A 4-pole piezoelectric vibration filter is formed by arranging two 2-pole filter sections on a single piezoelectric diaphragm. Therefore, the frequency adjustment method for the two-pole piezoelectric vibration filter described above can be applied as it is to each filter unit.

On the other hand, as shown in FIG. 8, the three-pole piezoelectric vibration filter 200 has a piezoelectric diaphragm 201 with a common electrode 202 formed on one main surface S1, and an input electrode 203, a ground electrode 205 and an output electrode on the other main surface S2. 204 are formed side by side with a gap G therebetween. The frequency characteristics of the three-pole piezoelectric vibration filter 200 are the first symmetric mode (vibration frequency Fs1) shown in FIG. 9(a), the oblique symmetric mode (vibration frequency Fa) shown in FIG. determined by the interaction with the second symmetrical mode (oscillating frequency Fs2) shown in 9(c).

As the frequency adjustment of the 3-pole piezoelectric vibration filter 200,
・Balance adjustment ・ΔF ratio adjustment ・ΔF adjustment (equivalent to band adjustment)
- Four kinds of processes for overall adjustment are performed (for example, Patent Document 2). Each of these steps is also selectively performed according to the frequency characteristics of the piezoelectric vibration filter at that time, and some steps may be omitted when there is no need for adjustment.

In the frequency adjustment of the three-pole piezoelectric vibration filter 200 , the ΔF adjustment corresponds to band adjustment for adjusting the passband width of the piezoelectric vibration filter 200 . The passband width of the piezoelectric vibration filter 200 is the difference (Fs2-Fs1) between the vibration frequency Fs2 of the second symmetric mode and the vibration frequency Fs1 of the first symmetric mode.

The ΔF adjustment (bandwidth adjustment) of the three-pole piezoelectric vibration filter 200 is an adjustment that mainly changes the vibration frequency Fs1 (hereinafter referred to as Fs1 adjustment) and adjustment mainly for changing the vibration frequency Fs2 (hereinafter referred to as Fs2 adjustment) are performed.

When widening the passband width, adjustment is performed so that the film thickness of the common electrode 202 in the area facing the gap G is increased relatively more than in other areas. That is, in the partial adjustment, the film thickness of the common electrode 202 in the region facing the gap G should be increased. In the ion partial adjustment, the film thickness of the common electrode 202 in the region facing the input electrode 203, the ground electrode 205 and the output electrode 204 should be reduced. The partial adjustment at this time is the Fs1 adjustment, and mainly the vibration frequency Fs1 changes greatly, but the vibration frequency Fs12 also changes at the same time (the change amount ΔFs1 of the vibration frequency Fs1 is larger than the change amount ΔFs2 of the vibration frequency Fs2). big). The ion partial adjustment at this time is the Fs2 adjustment, and mainly the vibration frequency Fs2 changes greatly, but the vibration frequency Fs1 also changes at the same time (the change amount ΔFs2 of the vibration frequency Fs2 is greater than the change amount ΔFs1 of the vibration frequency Fs1). is also large).

Conversely, when narrowing the passband width, the film thickness of the common electrode 202 in the region facing the gap G is relatively reduced compared to the other portions. That is, in the partial adjustment, the film thickness of the common electrode 202 in the region facing the input electrode 203, the ground electrode 205 and the output electrode 204 should be increased. In the ion partial adjustment, the film thickness of the common electrode 202 in the region facing the gap G should be reduced. The partial adjustment at this time is the Fs2 adjustment, and the ion partial adjustment at this time is the Fs1 adjustment.

In the band adjustment of the three-pole piezoelectric vibration filter 200, the user sets the adjustment amount of the vibration frequency Fs1 when performing the Fs1 adjustment, and sets the adjustment amount of the vibration frequency Fs2 when performing the Fs2 adjustment. In this setting, the same predictive adjustment as in the two-pole piezoelectric vibration filter 100 can be performed.

That is, the ratio of the amount of change ΔFs2 to the amount of change ΔFs1 when adjusting Fs1 (ΔFs2/ΔFs1) and the ratio of the amount of change ΔFs1 to the amount of change ΔFs2 when adjusting Fs2 (ΔFs1/ΔFs2) are the same as the frequency adjustment performed first. Since the predicted value can be obtained from the adjustment log of the piezoelectric vibration filter 200, it is possible to set an appropriate adjustment amount based on this predicted value.

The embodiments disclosed this time are exemplifications in all respects and are not grounds for restrictive interpretation. Therefore, the technical scope of the present invention is not to be interpreted only by the above-described embodiments, but is defined based on the claims. In addition, all changes within the meaning and range of equivalents to the scope of claims are included.

10 frequency adjustment device 11 adjustment processing unit 12 control unit (computing unit)
13 storage unit 14 display unit 15 input unit 100, 200 piezoelectric vibration filter 101, 201 piezoelectric diaphragm 102, 202 common electrode 103, 203 input electrode 104, 204 output electrode 205 ground electrode

Claims (8)

A frequency adjustment method for a piezoelectric vibration filter for adjusting frequency characteristics of each piezoelectric vibration filter for a plurality of piezoelectric vibration filters manufactured according to the same product standard,
The frequency adjustment method includes at least band adjustment for adjusting the passband width of one piezoelectric vibration filter by adjusting the passband width of the piezoelectric vibration filter and adjusting the passband width of the piezoelectric vibration filter to narrow it. and
After frequency adjustment including the band adjustment is performed on at least one piezoelectric vibration filter, when frequency adjustment is performed on another piezoelectric vibration filter,
calculating a predicted value that can be used for setting an adjustment amount in the band adjustment from the adjustment log of at least one piezoelectric vibration filter whose frequency characteristics have been adjusted;
For another piezoelectric vibration filter whose frequency characteristics are adjusted after the predicted value is calculated, an optimum adjustment amount in the band adjustment is calculated based on the predicted value, and the band is adjusted with the calculated adjustment amount. A frequency adjustment method for a piezoelectric vibration filter, comprising adjusting the frequency. A frequency adjustment method for a piezoelectric vibration filter according to claim 1,
The predicted value calculated from the adjustment log of the piezoelectric vibration filter whose frequency characteristics have been adjusted is calculated as an average value for a plurality of piezoelectric vibration filters, and the frequency adjustment for one piezoelectric vibration filter is completed. A frequency adjustment method for a piezoelectric vibration filter, wherein the value is updated by adding the adjustment result each time. A frequency adjustment method for a piezoelectric vibration filter according to claim 1 or 2,
The piezoelectric vibration filter is a two-pole or four-pole piezoelectric vibration filter,
The band adjustment is performed by Fs adjustment for adjusting the band of the symmetric mode and Fa adjustment for adjusting the band of the oblique symmetric mode,
The predicted value is the ratio (ΔFa/ΔFs) of the frequency change amount ΔFa in the oblique symmetric mode to the frequency change amount ΔFs in the symmetric mode when Fs adjustment is performed, and the frequency change in the oblique symmetric mode when Fa adjustment is performed. A frequency adjustment method for a piezoelectric vibration filter, wherein the frequency is calculated as a ratio (ΔFs/ΔFa) of a frequency change amount ΔFs in a symmetrical mode to an amount ΔFa. A frequency adjustment method for a piezoelectric vibration filter according to claim 1 or 2,
The piezoelectric vibration filter is a three-pole piezoelectric vibration filter,
The band adjustment is performed by Fs1 adjustment for adjusting the band of the first symmetric mode and Fs2 adjustment for adjusting the band of the second symmetric mode,
The predicted value is the ratio (ΔFs2/ΔFs1) of the frequency change amount ΔFs2 in the second symmetric mode to the frequency change amount ΔFs1 in the first symmetric mode when Fs1 adjustment is performed, and the second symmetric A frequency adjustment method for a piezoelectric vibration filter, characterized in that the ratio of a first symmetrical mode frequency variation ΔFs1 to a mode frequency variation ΔFs2 (ΔFs1/ΔFs2)”. A frequency adjustment device for a piezoelectric vibration filter for adjusting frequency characteristics of each piezoelectric vibration filter,
The frequency adjustment device can perform at least band adjustment for adjusting the passband width of one piezoelectric vibration filter by adjusting the passband width of the piezoelectric vibration filter to widen and adjusting the passband width of the piezoelectric vibration filter to narrow it. is a
a calculation unit that calculates a predicted value that can be used for setting an adjustment amount in the band adjustment from an adjustment log of at least one piezoelectric vibration filter whose frequency characteristics have been adjusted;
and a display section for displaying the predicted value calculated by the calculation section. A frequency adjustment device for a piezoelectric vibration filter according to claim 5,
The calculation unit is
calculating the predicted value each time the frequency characteristic is adjusted for one piezoelectric vibration filter;
The predicted value calculated for the one piezoelectric vibration filter is compared with the predicted value obtained from the adjustment log of the piezoelectric vibration filter whose frequency characteristics have been adjusted before, and the ratio in the comparison Alternatively, a frequency adjustment device for a piezoelectric vibration filter, which judges whether or not the difference is equal to or greater than a predetermined value, and issues a warning when the ratio or difference is equal to or greater than the predetermined value. A frequency adjustment device for a piezoelectric vibration filter according to claim 5 or 6,
The piezoelectric vibration filter is a two-pole or four-pole piezoelectric vibration filter,
The band adjustment is performed by Fs adjustment for adjusting the band of the symmetric mode and Fa adjustment for adjusting the band of the oblique symmetric mode,
The predicted value is the ratio of the frequency change amount ΔFa in the oblique symmetric mode to the frequency change amount ΔFs in the symmetric mode when Fs adjustment is performed (ΔFa/ΔFs), and the frequency change in the oblique symmetric mode when Fa adjustment is performed. A frequency adjustment device for a piezoelectric vibration filter, characterized in that it is calculated as a ratio (ΔFs/ΔFa) of a frequency change amount ΔFs in a symmetrical mode to an amount ΔFa. A frequency adjustment device for a piezoelectric vibration filter according to claim 5 or 6,
The piezoelectric vibration filter is a three-pole piezoelectric vibration filter,
The band adjustment is performed by Fs1 adjustment for adjusting the band of the first symmetric mode and Fs2 adjustment for adjusting the band of the second symmetric mode,
The predicted value is the ratio (ΔFs2/ΔFs1) of the frequency change amount ΔFs2 in the second symmetric mode to the frequency change amount ΔFs1 in the first symmetric mode when Fs1 adjustment is performed, and the second symmetry when Fs2 adjustment is performed A frequency adjustment device for a piezoelectric vibration filter, characterized in that it is calculated as a ratio (ΔFs1/ΔFs2) of a first symmetrical mode frequency change amount ΔFs1 to a mode frequency change amount ΔFs2.

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