Tuning-fork type angular velocity sensor, electromechanical leakage adjustment method, electromechanical leakage adjustment system, and inertial measurement device

Abstract

To provide a technique capable of relatively easily adjusting electromechanical leakage in a tuning-fork type angular velocity sensor without damaging a base material.SOLUTION: A tuning-fork type angular velocity sensor 10 includes at least two arms 2 and 3 and a base part 4 connected to the arms 2, for example. Each arm 2 has at least one of a drive electrode 5 for driving the arm and a detection electrode 6 for detecting an angular velocity. With reference to the center of the base part 4, adjustment electrodes 7 and 8 are disposed on both lateral sides. Appropriately trimming the adjustment electrodes 7 and 8 can adjust electromechanical leakage, whereby an electromechanical-leakage-adjusted tuning-fork type angular velocity sensor 10A can be obtained.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tuning fork angular velocity sensor, an electromechanical leakage adjustment method therefor, an electromechanical leakage adjustment system, and an inertial measurement unit, and more particularly to a tuning fork angular velocity sensor that can adjust electromechanical leakage without damaging the substrate. [Background technology]

[0002] Angular velocity sensors measure rotational speed, and their applications are expanding, including car navigation systems, automobile and robot attitude control, and image stabilization for cameras, etc. In these applications, the mainstream type utilizes the Coriolis force that occurs when an angular velocity is applied to a vibrating object, and detects the displacement of the sensor element due to the Coriolis force.

[0003] Such angular rate sensors have a vibration mode during steady-state operation (oscillating vibration) and a mode that vibrates when Coriolis force is generated (detection vibration). It is particularly important that these two vibration modes do not couple during steady-state operation, and that only oscillation vibration occurs. However, depending on the processing state of the sensor element, these two vibration modes may couple, and detection vibration may also occur during oscillation vibration. This phenomenon is called "electromechanical leakage." Because electromechanical leakage adversely affects the offset and stability of output when stationary, resulting in errors, it must be suppressed through improved processing precision and adjustments.

[0004] However, there is a limit to how much improvement in processing accuracy can be made to suppress electromechanical leakage, and processing variations also occur, making it difficult to completely suppress it. Therefore, a method of suppressing electromechanical leakage through adjustment is desirable. For example, in the case of a tuning fork-type angular rate sensor, one possible adjustment method is to change the vibration state by grinding the area near the base of the vibrating arm, thereby suppressing electromechanical leakage.

[0005] Many patent applications have been filed for technologies to suppress electromechanical leakage, etc., in tuning fork angular rate sensors. For example, the technologies disclosed in Patent Documents 1 and 4 listed below are technologies for providing a trimmable weight at the tip of the arm and trimming the weight, the technologies disclosed in Patent Documents 2 and 5 are technologies for providing a frequency adjustment electrode on the arm and trimming the adjustment electrode to adjust the frequency, and the technology disclosed in Patent Document 3 is a technology for adjusting electrical coupling by trimming the detection electrode. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-071706 "Tuning fork type vibration gyro" [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-017469 "Method for adjusting a vibrator for a piezoelectric vibration gyroscope" [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-310663 "Tuning fork type vibration gyroscope and its electrode trimming method" [Patent Document 4] Japanese Patent Application Publication No. 2013-167595 "Method for adjusting a three-axis angular velocity sensor" [Patent Document 5] Publication No. 98 / 047226 "AT-cut quartz crystal unit" Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the adjustment method of grinding the base of the arm mentioned above, for example, using a file or other tool, scratches can be made in the base material, which can worsen the Q value and potentially cause the oscillation vibration itself to become unstable. While laser grinding can also be considered, laser processing is difficult for piezoelectric materials such as LN (lithium niobate) and LT (lithium titanate), which transmit light. Even if grinding is possible, the heat generated during processing can denature the processed area, potentially leading to a deterioration in characteristics. An adjustment method that avoids these problems is needed.

[0008] Therefore, the problem that the present invention aims to solve is to provide a technology that can eliminate the problems of the conventional technology and adjust electromechanical leakage in a tuning fork angular rate sensor relatively easily without damaging the substrate. Another object of the present invention is to provide a technology for adjusting electromechanical leakage in a tuning fork angular rate sensor that does not cause a deterioration in the Q value, destabilization of oscillation vibration, or deterioration in characteristics due to denaturation of processed areas. [Means for solving the problem]

[0009] As a result of studying the above-mentioned problems, the inventors of the present application found that the above-mentioned problems could be solved by adopting a tuning fork angular rate sensor structure in which adjustment electrodes are provided on both sides of the center of the base as a reference, and by adjusting the left and right area balance by trimming the adjustment electrodes, and based on this, the present invention was completed. That is, the invention claimed in this application, or at least the invention disclosed therein, as a means for solving the above-mentioned problems is as follows.

[0010] [1] A tuning fork angular velocity sensor comprising at least two arms and a base portion connected to the arms, each arm having at least one of an oscillation electrode for driving the arm or a detection electrode for detecting angular velocity, and adjustment electrodes disposed on both sides of the center of the base portion. [2] The tuning fork angular velocity sensor according to [1], characterized in that it has an oscillation electrode, the oscillation electrode is connected to the base portion, and the adjustment electrode is connected to the oscillation electrode. [3] The tuning fork angular velocity sensor according to [2], wherein the adjustment electrodes are formed symmetrically with respect to the center of the base portion.

[0011] [4] The tuning fork angular velocity sensor according to [2], wherein the adjustment electrode is formed asymmetrically with respect to the center of the base portion. [5] A method for adjusting electromechanical leakage in a tuning fork angular velocity sensor according to any one of [1], [2], [3], and [4], characterized in that it comprises an adjustment method determination process for determining a necessary adjustment method based on the degree of electromechanical leakage, and a trimming process for trimming the adjustment electrode using the adjustment method obtained by the adjustment method determination process. [6] The method for adjusting electromechanical leakage of a tuning fork angular velocity sensor according to [5], characterized in that the area balance of the adjustment electrodes on both sides is adjusted so as to cancel out the electromechanical leakage. [7] An inertial measurement unit comprising the tuning fork angular velocity sensor according to any one of [1], [2], [3], and [4]. [8] A system for adjusting electromechanical leakage in a tuning fork angular velocity sensor according to any one of [1], [2], [3], and [4], characterized in that it comprises an adjustment method determination unit that determines a necessary adjustment method based on the degree of electromechanical leakage, and a trimming unit that trims the adjustment electrode using the adjustment method determined by the adjustment method determination unit. [Effects of the Invention]

[0012] The tuning fork angular rate sensor, its electromechanical leakage adjustment method, electromechanical leakage adjustment system, and inertial measurement unit of the present invention are configured as described above, and therefore, in the tuning fork angular rate sensor, electromechanical leakage can be adjusted by trimming the adjustment electrode without damaging the substrate, making it possible to relatively easily highly stabilize the angular rate sensor. According to the present invention, electromechanical leakage adjustment in the tuning fork angular rate sensor can be performed without causing deterioration of the Q value, destabilization of oscillation vibration, or deterioration of characteristics due to denaturation of the processed area.

[0013] The techniques disclosed in the above documents differ from the present invention in at least one of the adjustment method, adjustment purpose, and trimming position. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram showing an example of a planar configuration of a tuning fork angular velocity sensor according to the present invention; [Figure 1-2] FIG. 1 is a plan view illustrating an example of an electromechanical leakage adjusted tuning fork angular velocity sensor. [Figure 2] FIG. 1 is a flow chart showing the configuration of a method for adjusting electromechanical leakage of a tuning fork angular velocity sensor according to the present invention. [Figure 3] FIG. 10 is an arm end view showing an example of a tuning fork angular velocity sensor having an arm angle error that requires adjustment. [Figure 3-2] 4 is an explanatory diagram showing the planar configuration of the tuning fork angular velocity sensor of the present invention according to the example shown in FIG. 3. FIG. [Figure 3-3] 3A and 3B are graphs showing oscillation response simulation results in the example shown in FIGS. [Figure 4] 3-1 is an explanatory diagram showing a planar configuration of the tuning fork angular velocity sensor of the present invention shown in FIG. 3-2 after the electromechanical leakage adjusting method of the present invention is applied; FIG. [Figure 4-2] 5 is a graph showing the results of an oscillation response simulation of the tuning fork angular velocity sensor of the present invention after adjustment shown in FIG. 4. [Figure 5] 1 is an explanatory diagram conceptually showing the configuration of an electromechanical leakage adjustment system for a tuning fork angular velocity sensor according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below with reference to the drawings. 1 is an explanatory diagram showing an example of the planar configuration of a tuning fork angular velocity sensor of the present invention. As shown in the figure, this tuning fork angular velocity sensor 10 mainly consists of at least two arms 2 and 3 and a base 4 connected to the arms 2, each arm 2 having at least one of an oscillation electrode 5 that drives it or a detection electrode 6 that detects angular velocity, and adjustment electrodes 7 and 8 disposed on both sides of the center of the base 4.

[0016] If electromechanical leakage occurs in the tuning fork angular velocity sensor 10 having such a configuration, the electromechanical leakage can be adjusted by applying appropriate or corresponding trimming to the adjustment electrodes 7 and 8 provided on both sides of the center of the base portion 4, thereby producing an electromechanical leakage adjusted tuning fork angular velocity sensor 10A (see Figures 1-2 below).

[0017] FIG. 1-2 is a plan view illustrating an example of a tuning fork angular velocity sensor after electromechanical leakage adjustment. As shown in the figure, the adjustment electrode 7 (FIG. 1) is trimmed to form post-trimming adjustment electrodes 7a and 7b. This results in a tuning fork angular velocity sensor 10A after electromechanical leakage adjustment. Note that the trimming of the post-trimming adjustment electrodes 7a and 7b is an example. Specific methods that may be included in the trimming according to the present invention will be described later.

[0018] 1, the tuning fork angular velocity sensor 10 of the present invention can be configured to have an oscillation electrode 5, which is connected to the base portion 4, and adjustment electrodes 7 and 8 which are connected to the oscillation electrode 5. Therefore, the adjustment electrodes 7 and 8 can also be considered to be part of the oscillation electrode 5. In this case, the adjustment portions (7, 8) are part of the oscillation electrode 5.

[0019] By imbalancing the areas and arrangements of the adjustment electrodes 7 and 8 provided on the left and right sides of the base portion 4, the oscillation vibration and the detection vibration are coupled, resulting in a phenomenon similar to electromechanical leakage. Therefore, to counter electromechanical leakage caused by errors during the manufacturing of the sensor element, the adjustment electrodes are trimmed to create an imbalance, thereby canceling out the electromechanical leakage. This is the concept behind electromechanical leakage adjustment in this invention.

[0020] The adjustment electrodes of this tuning fork angular velocity sensor can be configured to be formed symmetrically with respect to the center of the base portion 4, as shown as adjustment electrodes 7 and 8 in Fig. 1, which is a more preferable configuration. However, a configuration in which the electrodes are formed asymmetrically with respect to the center of the base portion is not excluded from the present invention and is within the scope of the invention.

[0021] For example, electromechanical leakage may inevitably occur due to the arrangement of the electrodes that make up this tuning fork angular rate sensor. In such cases, the adjustment electrodes may be configured to have an unbalanced shape, arrangement, and size from the beginning, depending on the electrode arrangement. Also, the adjustment electrodes may have an unbalanced shape, arrangement, and size from the left to the right, depending on the quirks and tendencies of processing, etc.

[0022] 2 is a flow diagram showing the configuration of the electromechanical leakage adjustment method for a tuning fork angular rate sensor of the present invention. As shown in the figure, the electromechanical leakage adjustment method for a tuning fork angular rate sensor mainly consists of an adjustment method determination process P10, which determines the necessary adjustment method based on the level of electromechanical leakage, and a trimming process P20, which trims the adjustment electrodes of tuning fork angular rate sensor 210 using the adjustment method determined in adjustment method determination process P10.

[0023] According to the present electromechanical leakage adjustment method for tuning fork angular velocity sensors having such a configuration, in the adjustment method determination process P10, a necessary adjustment method is determined based on the level of electromechanical leakage of tuning fork angular velocity sensor 210 requiring adjustment, and in the trimming process P20, trimming of the adjustment electrodes of tuning fork angular velocity sensor 210 requiring adjustment is performed using the adjustment method determined in the adjustment method determination process P10, thereby obtaining tuning fork angular velocity sensor 210A whose electromechanical leakage has been adjusted.

[0024] As described above, the electromechanical leakage adjustment method for this tuning fork angular rate sensor can be a method of adjusting the area balance of the left and right adjustment electrodes to cancel out the electromechanical leakage. In other words, this method involves trimming either the left or right adjustment electrode by an appropriate amount depending on the magnitude and phase of the electromechanical leakage, by removing a certain area of ​​the adjustment electrode, but is not limited to this. For example, it is also possible to cut the electrode and separate a portion from the oscillation electrode. Also, it is convenient to use laser light for trimming.

[0025] The "appropriate amount" of adjustment can be determined by evaluating the characteristics of the tuning fork angular rate sensor before adjustment. For example, after the manufacturing process of the tuning fork angular rate sensor is completed, the output value measured in a characteristic evaluation test before shipping is compared with the sensor specifications, and the bias for the error is trimmed so that the measured output value matches the ideal value specified in the specifications.

[0026] This "error amount," i.e., the "appropriate amount to be adjusted," can be calculated automatically, for example, based on data from a trimming example. The process of determining the appropriate amount to be adjusted (not shown), including the case where the appropriate amount is 0 (no adjustment required), and the process P10 of determining the adjustment method based on that determination, may be automated. The subsequent trimming process P20 may also be automated.

[0027] An example of when electromechanical leakage occurs is when the angle of the arm of a tuning fork angular velocity sensor is not a right angle. An example of an adjustment method for such a case will be described. 3 is an arm end view showing an example of a tuning fork angular velocity sensor 310 having an arm angle error as an example of a tuning fork angular velocity sensor that requires adjustment, in which the angle error of arm 32 (33) is +0.1°. In other words, while the total angle should be 90.0°, one pair of diagonal angles is 90.1° and the remaining diagonal angles are 89.9°.

[0028] Fig. 3-2 is an explanatory diagram showing an example of the planar configuration of the tuning fork angular velocity sensor of the present invention shown in Fig. 3. Tuning fork angular velocity sensor 310 of this example is an example in which adjustment electrodes 37 and 38 are formed asymmetrically, and adjustment electrode 38 in particular is configured as a target for trimming when adjustment is required.

[0029] Figure 3-3 is a graph showing the results of an oscillation response simulation for the +0.1° example shown in Figures 3 and 3-2, with the horizontal axis representing frequency and the vertical axis representing impedance. As shown in the figure, in addition to the oscillation vibration response, a detection vibration response also occurs, which is undesirable. Adjustments are required.

[0030] 4 is an explanatory diagram showing the planar configuration of the tuning fork angular rate sensor shown in FIG. 3-2 after the electromechanical leakage adjustment method of the present invention has been applied. As shown, in the tuning fork angular rate sensor 310A after electromechanical leakage adjustment, the adjustment electrode 38 of the tuning fork angular rate sensor 310 shown in FIG. 3-2 is divided into a post-trim adjustment electrode 38a and a floating electrode 38b by trimming. Since the floating electrode 38b is separated from the post-trim adjustment electrode 38a, no oscillation signal is applied to the floating electrode 38b. This results in an imbalance between the adjustment electrode 37 and the post-trim adjustment electrode 38a.

[0031] Figure 4-2 is a graph showing the results of an oscillation response simulation for the tuning fork angular rate sensor of the present invention after adjustment shown in Figure 4, where the horizontal axis is frequency and the vertical axis is impedance. As shown in the figure, the detectable vibration response that existed before adjustment is no longer detected. This indicates that proper adjustment has been made according to the present invention.

[0032] An inertial measurement unit including the tuning fork angular velocity sensor 10 having any of the above-described configurations is also within the scope of the present invention.

[0033] 5 is an explanatory diagram conceptually illustrating the configuration of an electromechanical leakage adjustment system for a tuning fork angular velocity sensor according to the present invention. As shown in the figure, the electromechanical leakage adjustment system 1000 for a tuning fork angular velocity sensor is mainly composed of an adjustment method determination unit 400 that determines the necessary adjustment method based on the level of electromechanical leakage, and a trimming unit 600 that trims the adjustment electrode using the adjustment method determined by the adjustment method determination unit 400.

[0034] In the thus configured electromechanical leakage adjustment system 1000 for a tuning fork angular velocity sensor, the adjustment method determination unit 400 determines the necessary adjustment method based on the level of electromechanical leakage, and the trimming unit 600 trims the adjustment electrodes using the adjustment method determined by the adjustment method determination unit 400, thereby adjusting the electromechanical leakage of the tuning fork angular velocity sensor.

[0035] The electromechanical leakage adjustment system 1000 for the tuning fork angular velocity sensor can be a system in which either or both of the adjustment method determination unit 400 and the trimming unit 600 are automated. The system 1000 can further include a functional unit (not shown) that determines the appropriate amount to be adjusted, including when the appropriate amount is 0 (no adjustment required), in which case this functional unit can also be configured to be automated. [Industrial Applicability]

[0036] The tuning fork angular rate sensor, its electromechanical leakage adjustment method, electromechanical leakage adjustment system, and inertial measurement unit of the present invention can adjust electromechanical leakage without damaging the base material of the tuning fork angular rate sensor, thereby achieving high stability of the angular rate sensor. Therefore, this invention has high industrial applicability in the fields of angular rate sensor manufacturing, use, and all related fields. [Explanation of symbols]

[0037] 2, 3, 32, 33...Arm 4, 34...Base 5, 35...Oscillation electrode 6, 36...Detection electrodes 7, 8, 37, 38…Adjustment electrode 7a, 7b, 38a... Post-trimming adjustment electrodes 10, 210, 310... Tuning fork angular rate sensor 10A, 210A, 310A... Electromechanical Leakage Adjusted Tuning Fork Angular Rate Sensor P10…Adjustment method decision process P20...Trimming process 400...Adjustment method determining section 600...Trimming section 1000... Electromechanical leakage adjustment system for tuning fork type angular velocity sensor

Claims

1. at least two arms; a base portion connected to the arm, Each arm has at least one of an oscillation electrode for driving it and a detection electrode for detecting angular velocity, Adjustment electrodes are arranged on both sides of the center of the base portion. A tuning fork type angular velocity sensor characterized by:

2. 2. The tuning fork angular velocity sensor according to claim 1, further comprising an oscillation electrode connected to the base portion, and the adjustment electrode connected to the oscillation electrode.

3. 3. The tuning fork angular velocity sensor according to claim 2, wherein the adjustment electrodes are formed symmetrically with respect to the center of the base portion.

4. 3. The tuning fork angular velocity sensor according to claim 2, wherein the adjustment electrode is formed asymmetrically with respect to the center of the base portion.

5. A method for adjusting electromechanical leakage in a tuning fork angular velocity sensor according to any one of claims 1, 2, 3 and 4, comprising: an adjustment method determination process for determining a necessary adjustment method based on the degree of electromechanical leakage; a trimming step of trimming the adjustment electrode using the adjustment method obtained by the adjustment method determination step; 1. A method for adjusting electromechanical leakage of a tuning fork angular velocity sensor, comprising:

6. 6. The method for adjusting electromechanical leakage of a tuning fork angular velocity sensor according to claim 5, wherein the area balance of the adjustment electrodes on both sides is adjusted so as to cancel out the electromechanical leakage.

7. 5. An inertial measurement unit comprising the tuning fork angular velocity sensor according to claim 1.

8. A system for adjusting electromechanical leakage in a tuning fork angular velocity sensor according to any one of claims 1, 2, 3 and 4, comprising: an adjustment method determination unit that determines a necessary adjustment method based on the degree of electromechanical leakage; a trimming unit that trims the adjustment electrode by the adjustment method determined by the adjustment method determination unit; 1. An electromechanical leakage adjustment system for a tuning fork type angular velocity sensor, comprising:

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