JPH09102722A - Polarization control method of piezoelectric resonator and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a piezoelectric resonator at desired polarization with high accuracy and also to improve productivity of the resonator with no skill required by repeating measurement of the frequency difference and application of voltage in a fixed cycle until the frequency difference is set within a cross range. SOLUTION: A piezoelectric resonator 1 held at a terminal 13 in a 1st area A of a polarization degree control device 11 is moved to a 2nd area B by a conveyor belt 12. The difference is measured between the resonance frequency and the anti-resonance frequency of the resonator 1. When it is decided that the frequency difference is larger than the cross difference, the voltage of a prescribed level is applied to the moved resonator 1 for a fixed time in an adjacent area C. These processes are repeated in both adjacent areas B and C until the frequency difference is set within the cross difference. These processes are repeated until the frequency difference becomes within the cross difference, a non-defective resonator 1 is picked up when returned to the area A. As a result, the resonator 1 can be easily controlled at desired polarization with no expertness required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and device for adjusting the polarization degree of a piezoelectric resonator.

[0002]

2. Description of the Related Art Generally, the piezoelectricity of a piezoelectric ceramic resonator is provided by applying a DC voltage to the piezoelectric ceramic resonator.

[0003]

However, adjustment of the polarization degree of the piezoelectric ceramic resonator is a work requiring skill because various conditions such as applied voltage, applied time, and ambient temperature affect each other. It was also difficult to obtain a desired degree of polarization with high accuracy. Therefore, an object of the present invention is to provide a method for adjusting the degree of polarization of a piezoelectric resonator and an apparatus therefor that can obtain a desired degree of polarization with high accuracy and does not require any skill.

[0004]

In order to achieve the above object, a method of adjusting the polarization degree of a piezoelectric resonator according to the present invention is
(A) Resonance frequency fr and antiresonance frequency fa of the piezoelectric resonator
The first step of measuring the frequency difference Δf of, and (b) the second step of applying a predetermined voltage to the piezoelectric resonator,
(C) In the first step and the second step, the frequency difference Δ
Alternately repeating until f is within the tolerance range.

The polarization adjusting device for a piezoelectric resonator according to the present invention comprises (d) a first area for attaching and detaching the piezoelectric resonator,
(E) a second area for measuring the frequency difference Δf between the resonance frequency fr and the anti-resonance frequency fa of the piezoelectric resonator, and (f) the second area and the second area are alternately arranged, and the frequency difference Δf is outside the tolerance. For example, a third area for applying a predetermined voltage to the piezoelectric resonator is provided.

Furthermore, the polarization degree adjusting apparatus for a piezoelectric resonator according to the present invention comprises (g) an insulating member having a plurality of sets of terminals,
(H) Resonance frequency f of the piezoelectric resonator sandwiched between the terminals
control means for controlling a first step of measuring a frequency difference Δf between r and the anti-resonance frequency fa, and a second step of applying a predetermined voltage to the piezoelectric resonator if the frequency difference Δf is outside a tolerance. (I) storage means for storing the frequency difference Δf of the piezoelectric resonator, and (j) handling means for attaching / detaching the piezoelectric resonator to / from the terminal.

[0007]

Operation: Until the frequency difference Δf falls within the tolerance range, the measurement of the frequency difference Δf and the voltage application to the piezoelectric resonator are automatically repeated in a constant cycle.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method for adjusting the polarization degree of a piezoelectric resonator and an apparatus therefor according to the present invention will be described below with reference to the accompanying drawings. [First Embodiment, FIGS. 1 to 5] In the piezoelectric ceramic resonator, the current flowing in the resonator is maximized at the resonance frequency fr, and the impedance is minimized. On the other hand, at the anti-resonance frequency fa, the current flowing in the resonator is minimum and the impedance is maximum. The polarization degree is generally measured by the frequency difference Δ between the resonance frequency fr and the anti-resonance frequency fa.
It is evaluated by f. That is, when the polarization degree increases, Δf
Is also increased and the polarization degree is decreased, Δf is also decreased.

FIG. 1 is a flow chart of a method for adjusting the polarization degree of a piezoelectric resonator. First, in step S1, the frequency difference Δ between the resonance frequency fr and the anti-resonance frequency fa as shown in FIG.
A DC voltage is applied to the piezoelectric ceramic resonator so that f becomes slightly larger than the designed value Δf ₀ to perform temporary polarization, and a piezoelectric ceramic resonator having a polarization degree slightly larger than the designed value is prepared.

Next, in step S2, the temporarily polarized piezoelectric ceramic resonator is set in a polarization degree adjusting device (described later). For the piezoelectric ceramic resonator set in the polarization degree adjusting device, after the frequency difference Δf is measured in step S3, it is determined in step S4 whether Δf is within a predetermined tolerance. If it is determined that Δf is out of the tolerance, then
In step S6, it is determined whether Δf is larger than the tolerance. If Δf is larger than the tolerance, a reverse DC voltage is applied to the piezoelectric ceramic resonator for a predetermined time in step S7,
Reduce Δf. If Δf is smaller than the tolerance, a positive DC voltage is applied to the piezoelectric ceramic resonator for a predetermined time in step S8 to increase Δf. On the other hand, step S4
Then, if it is determined that Δf is within the tolerance, no voltage is applied to the piezoelectric ceramic resonator.

Next, in step S9, it is determined whether or not the tact time has expired. What is takt time?
This is the time from setting the piezoelectric ceramic resonator in the polarization adjuster to removal. When it is determined that the tact time has not ended, the process further returns to step S3,
The measurement of Δf (step S3) and the voltage application (steps S7 and S8) are repeated again. Then, step S9
If it is determined that the takt time has ended, the piezoelectric ceramic resonator is removed from the polarization degree adjusting device in step S10.

Next, a method of adjusting the polarization degree of the piezoelectric ceramic resonator will be specifically described by taking the polarization degree adjusting device 11 shown in FIG. 3 as an example. The polarization degree adjusting device 11 has a configuration in which a plurality of pairs of terminals 13 are provided on an annular conveyor belt 12 that is rotationally driven in the clockwise direction. The terminal 13 holds the resonator 1 by its spring force, and is also used for measuring Δf of the resonator 1 and applying a DC voltage to the resonator 1. A first area A for attaching and detaching the resonator 1 is set on the left side portion of the device 11, and a second area B for measuring Δf of the resonator 1 in the driving direction of the conveyor belt 12 and the resonator 1 are provided.
The third areas C to which the DC voltage is applied are set alternately. Each of the second area B and the third area C is preferably set at about 20 locations.

The device 11 further includes a computer (not shown), a DC voltage applying circuit, and Δf measuring circuits 20 and 30 shown in FIG. 4 or 5. The Δf measurement circuit 20 shown in FIG.
It is a self-excited oscillating circuit provided with the above. Usually, it is necessary to prepare separate oscillating circuits for the resonance frequency fr and the anti-resonance frequency fa. Further, the Δf measurement circuit 30 shown in FIG. 5 is a circuit that roughly includes an AC power supply 31 to which a signal whose frequency is swept from the outside is added and an ammeter 32, and a current flowing in the resonator 1 at the resonance frequency fr. Is maximum,
This utilizes the property that the current flowing in the resonator 1 is minimized at the anti-resonance frequency fa. The takt time, the DC positive voltage value and the DC reverse voltage value to be applied to the resonator 1, and the tolerance range of Δf are keyed into the computer in advance. The direct-current positive voltage and the direct-current reverse voltage are set to voltages at which electric discharge does not occur in the air and the resonator 1 is not destroyed. Preferably, the reverse voltage is set to about 80% of the positive voltage.

The resonator 1 held by the terminal 13 in the first area A is moved to the second area B by the conveyor belt 12. In the second area B, the frequency difference Δf of the resonator 1 is the Δf measuring circuit 20, 3 shown in FIG. 4 or 5.
0 (step S3). The resonator 1 is
Preliminary polarization is performed so that Δf is slightly larger than the design value Δf ₀ , so Δf larger than the tolerance is usually obtained as measurement data. The obtained measurement data is transmitted to the computer, and the computer determines whether Δf is within the tolerance (step S4) and whether Δf is greater than the tolerance (step S6).

When it is determined that the frequency difference Δf is larger than the tolerance, a control signal for applying a reverse voltage is transmitted from the computer to the DC voltage applying circuit. Then, the DC reverse voltage is applied to the resonator 1 moved to the third area C by the conveyor belt 12 for a certain period of time synchronized with the tact time (step S7). In this way, Δf of the resonator 1 becomes small and approaches the design value Δf ₀ .

Further, the resonator 1 moved by the conveyor belt 12 from the third area C to the second area B adjacent to the right side of the third area C is again in the second area B.
Δf is measured (step S3). Then, it is determined whether Δf is within the tolerance within the computer (step S
4) and whether Δf is larger than the tolerance (step S6) are sequentially determined. When it is determined that Δf is larger than the tolerance again, the DC reverse voltage is applied to the resonator 1 in the third area C for a certain period of time synchronized with the tact time (step S7). On the contrary, when it is determined that Δf is smaller than the tolerance, the DC positive voltage is applied to the resonator 1 in the third area C for a certain period of time synchronized with the takt time (step S
8), Δf of the resonator 1 increases and approaches the design value Δf ₀ . Thus, the voltage is repeatedly applied every time the resonator 1 moves to the third area C until Δf falls within the tolerance.

On the other hand, when Δf is within the tolerance, no voltage is applied even if the resonator 1 moves to the third area C.
Then, if Δf is within the tolerance when the resonator 1 passes through the final third area C and returns to the first area A again, it is removed from the polarization degree adjusting device as a good product (step S10). If Δf is not within the tolerance, it is not removed and moved again by the conveyor belt 12 to the second area B and the third area C.

[Second Embodiment, FIGS. 6 to 10] FIG. 6 shows a polarization degree adjusting device 41 of the second embodiment. The polarization adjusting device 41 includes a plurality of sets of terminals 4 on an insulating flat plate 42.
3 are provided. The set of terminals 43 can hold the resonator 1 by its spring force. One end of the terminal 43 is led out to the back surface of the insulating flat plate 42 and serves as an electrode pad 43a.

A voltage application probe holder 45 and a frequency difference Δf measurement probe holder 47 are arranged on the back surface side of the insulating flat plate 42. Each holder 45, 47
Probes 46 and 48 are planted on the upper surface of the probe, and a pattern (not shown) for transmitting a DC voltage or a Δf measurement signal to the probes 46 and 48 is provided inside or on the surface of the holders 45 and 47. ) Is provided. During the polarization degree adjusting operation, the holders 45 and 47 are alternately exchanged to bring the probes 46 and 48 into contact with the electrode pad 43a. In this way, a plurality of resonators 1 can be processed simultaneously. However, the voltage application probe holder and the Δf measurement probe holder do not have to be separate parts, and both the voltage application probe 51 and the measurement probe 52 are implanted in one holder 50 as shown in FIG. 7. It may be one. During the polarization degree adjusting operation, the holder 50 is moved so that the probes 51 and 52 alternately contact the electrode pad 43a.

FIG. 8 is an electrical equivalent circuit diagram showing the entire system of the polarization degree adjusting device 41. As shown in FIG. 8, when the probe 46 contacts the electrode pad 43a, the probe 4
Reference numeral 6 is electrically connected to a DC power supply 55 and constitutes a DC voltage application circuit. When the probe 48 comes into contact with the electrode pad 43a, the probe 48 is connected to an AC power source 57 and an ammeter 58 to which a signal whose frequency is swept from the outside is added, and Δ
f Configure the measurement circuit. This Δf measuring circuit utilizes the property that the current flowing in the resonator 1 is maximized at the resonance frequency fr and the current flowing in the resonator 1 is minimized at the anti-resonance frequency fa. 56 is a protective resistor,
It is not necessary.

The controller 71 includes a probe holder 45,
47 is replaced every predetermined time, frequency sweep of a signal added to the AC power supply 57 is executed, data of each resonator 1 obtained by the ammeter 58 is stored in the memory 72, or X- This is for controlling the Y robot 73. A method of adjusting the polarization degree of the piezoelectric ceramic resonator 1 using the polarization degree adjusting device 41 having the above configuration will be described.

The resonators 1 which are provisionally polarized and whose degree of polarization is slightly larger than the design value are set in each of the plurality of sets of terminals 43. Based on the control signal from the controller 71, the measurement probe holder 47 moves to bring the probe 48 into contact with the electrode pad 43a. Next, the frequency of the signal applied to the AC power supply 57 is swept by the controller 71, and the current value flowing through the resonator 1 is measured by each ammeter 58. The frequency difference Δf is calculated in the controller 71 based on the obtained current value data of each resonator 1.
The value of Δf of each resonator 1 is stored in the memory 72.

Next, based on the control signal from the controller 71, the measuring probe holder 47 is removed, and instead the probe 46 of the voltage applying probe holder 45 is brought into contact with the electrode pad 43a. The resonator 1 has a DC power supply 55.
The reverse DC voltage is applied for a certain period of time. In this way, Δf of the resonator 1 becomes small and approaches the design value Δf ₀ .

Further, based on a control signal from the controller 71, the voltage application probe holder 45 is removed,
Instead, the probe 48 of the measurement probe holder 47 is brought into contact with the electrode pad 43a, and then the Δf of each resonator 1 is again measured.
Is measured and recorded in the memory 72. Controller 7
Within 1, it is determined whether Δf is within the tolerance, and if there is a resonator 1 with Δf within the tolerance, the controller 7
After the resonator 1 is taken out from the terminal 43 by the arm 74 of the XY robot 73 based on the control signal from the terminal 1 (see FIGS. 9 and 10), the unadjusted resonator 1 is moved to the terminal 4
It is pinched (that is, taken in) by 3. However, it is not necessary to take in the unadjusted resonator 1 at the same time as taking out the adjusted resonator 1, and Δf after several cycles
It may be performed at the time of measurement.

The arm 74 does not necessarily have to be used for taking out and taking in the resonator 1, and two types, that is, taking out and taking in, of the resonator 1 are prepared so as to move separately. Good. Further, a mechanism for stocking the unadjusted resonator 1 and a mechanism for stocking the adjusted resonator 1 are provided in the arm, and after the adjusted resonator 1 is taken out from the terminal 43, the unadjusted resonator 1 is promptly obtained. To terminal 4
It may be sandwiched between the three.

The resonator 1 whose Δf is out of the tolerance is kept as it is. When the work of taking out the resonator whose Δf is within the tolerance and the work of taking in the unadjusted resonator are completed, the measuring probe holder 47 is removed based on the control signal from the controller 71, and the voltage applying probe is used instead. 46 is brought into contact with the electrode pad 43a. A DC reverse voltage is applied to the resonator 1 by the DC power supply 55 for a certain period of time.
Thus, the voltage applying step and the Δf measuring step are repeated until Δf of the resonator 1 is within the tolerance.

The polarization degree of each resonator 1 is independently adjusted by the controller 71. Therefore, as the voltage application step for adjusting the polarization degree and the Δf measurement step are repeated, the resonator 1 on the insulating flat plate 42 is randomly taken out and taken in.
This is because the processing may be completed early in some cases and may be completed in some cases due to variations in the polarization degree of the resonator 1. However,
The resonator 1 for which Δf does not fall within the tolerance even if it is processed for a certain time or longer is forcibly taken out.

[Third Embodiment, FIGS. 11 and 12] FIG.
As shown in FIG. 1, the polarization degree adjusting device 59 of the third embodiment.
Is provided with a plurality of terminal pairs 61 (both of which are shown in FIG. 11) which are used for both voltage application and Δf measurement on one holder 60 made of an insulating member. The terminal pair 61 can hold the resonator 1 by its spring force. A voltage applying lead wire 62 and a Δf measuring lead wire 63 are connected to one end of the terminal pair 61. FIG.
As shown in FIG. 2, the lead wire 62 is connected to a DC power supply 66 via a switch 65, and constitutes a DC voltage application circuit. The lead wire 63 is connected via a switch 68 to an AC power source 69 and an ammeter 70 to which a frequency-swept signal is added, and constitutes a Δf measuring circuit. This Δf measuring circuit utilizes the property that the current flowing in the resonator 1 is maximized at the resonance frequency fr and the current flowing in the resonator 1 is minimized at the anti-resonance frequency fa. However, in FIG. 12, 64 is a protection resistor.

The controller 71 controls ON / OFF of the switches 65 and 68, frequency sweep of the AC power source 69, or stores data of each resonator 1 obtained by the ammeter 70 in the memory 72, or an XY robot. It is for controlling 73. The polarization degree enforcing device 59 is controlled by the controller 71 to switch the switches 65 and 6 at arbitrary timing.
Since 8 can be turned on and off, it can be adjusted to the time required for taking out and taking in the resonator 1.

[Other Embodiments] The polarization degree adjusting method and device for a piezoelectric resonator according to the present invention are not limited to the above-mentioned embodiment, but can be variously modified within the scope of the invention. .

In step S1, the piezoelectric ceramic resonator is provisionally polarized so that the frequency difference Δf between the resonance frequency fr and the anti-resonance frequency fa becomes slightly smaller than the design value Δf ₀ , and then Δf falls within a predetermined tolerance. You may do it. Further, the piezoelectric ceramic resonator may have three or more terminals. Further, in the polarization degree adjusting device, the frequency difference Δ
The configuration may be other than that of the above-described embodiment as long as a mechanism is provided so that the adjusting DC voltage is not continuously applied to the resonator in which f is within the tolerance.

[0032]

As is apparent from the above description, according to the present invention, until Δf of the frequency difference between the resonance frequency fr and the anti-resonance frequency fa falls within the tolerance range, the measurement of Δf and the voltage applied to the piezoelectric resonator. Since the application is automatically repeated in a fixed cycle, the desired Δf can be obtained without requiring skill.
That is, it is possible to easily adjust to the desired degree of polarization,
The productivity of the piezoelectric resonator can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a first embodiment of a method of adjusting the polarization degree of a piezoelectric resonator according to the present invention.

FIG. 2 is a graph showing the impedance characteristics of a tentatively polarized piezoelectric resonator.

FIG. 3 is a schematic configuration diagram showing a first embodiment of a polarization degree adjusting device for a piezoelectric resonator according to the present invention.

FIG. 4 is an electric circuit diagram for measuring a resonance point and an anti-resonance point of a piezoelectric resonator.

FIG. 5 is another electric circuit diagram for measuring the resonance point and the anti-resonance point of the piezoelectric resonator.

FIG. 6 is a front view showing a second embodiment of the polarization degree adjusting device for a piezoelectric resonator according to the present invention.

FIG. 7 is a front view showing a modified example of the probe holder.

8 is an electrical equivalent circuit diagram showing the entire system of the polarization degree adjusting device shown in FIG.

FIG. 9 is a front view showing a procedure for taking out a piezoelectric resonator from a terminal.

FIG. 10 is a front view showing the procedure following FIG. 9;

FIG. 11 is a front view showing a third embodiment of the polarization degree adjusting device for a piezoelectric resonator according to the present invention.

12 is an electrical equivalent circuit diagram showing a system of the entire polarization degree adjusting device shown in FIG.

[Explanation of symbols]

 11 ... Polarization degree adjusting device 12 ... Conveying belt 13 ... Terminals 20, 30 ... Δf measuring circuit A ... First area B ... Second area C ... Third area 41 ... Polarization degree adjusting device 42 ... Insulating flat plate 43 ... Terminal 59 ... Polarization degree adjusting device 60 ... Holder 61 ... Terminal pair 71 ... Controller 72 ... Memory 73 ... XY robot

Claims (3)

[Claims] 1. A first step of measuring a frequency difference Δf between a resonance frequency fr of a piezoelectric resonator and an anti-resonance frequency fa, and a second step of applying a predetermined voltage to the piezoelectric resonator. A method for adjusting the polarization degree of a piezoelectric resonator, wherein the step and the second step are alternately repeated until the frequency difference Δf falls within a tolerance range. 2. A first area for attaching and detaching a piezoelectric resonator, a second area for measuring a frequency difference Δf between a resonance frequency fr and an anti-resonance frequency fa of the piezoelectric resonator, and an alternating area for the second area. A polarization degree adjusting device for a piezoelectric resonator, comprising: a third area for applying a predetermined voltage to the piezoelectric resonator if the frequency difference Δf is out of tolerance. 3. An insulating member having a plurality of sets of terminals, a first step of measuring a frequency difference Δf between a resonance frequency fr and an anti-resonance frequency fa of a piezoelectric resonator sandwiched by the terminals,
If the frequency difference Δf is outside the tolerance, a control unit that controls a second step of applying a predetermined voltage to the piezoelectric resonator, a storage unit that stores the frequency difference Δf of the piezoelectric resonator, and the piezoelectric resonance A polarization degree adjusting device for a piezoelectric resonator, comprising: a means for attaching and detaching the child to and from the terminal.