Method of manufacturing physical quantity detection device, and physical quantity detection device

Abstract

To provide a method of manufacturing a physical quantity detection device that offers improved sensitivity of vibration characteristics, and to provide a physical quantity detection device.SOLUTION: A method of manufacturing a physical quantity detection device is provided, the method comprising a first step of preparing a vibration element, a second step of adjusting at least one of driving vibration arms, and a third step of electrically connecting a first detection electrode 40 to a third detection electrode 44 and electrically connecting a second detection electrode 42 to a fourth detection electrode 46.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a physical quantity detection device and a physical quantity detection device.

Background Art

[0002] Patent Document 1 discloses a physical quantity detection device, that is, a gyro sensor, in which the detection sensitivity is improved by receiving the charge amounts from both the positive and negative electrodes without grounding one of the positive and negative electrodes of the detection arm.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration described in Patent Document 1, the first detection electrode and the fourth detection electrode are electrically connected, and the second detection electrode and the third detection electrode are electrically connected. Since it is not known from which detection vibrating arm the unnecessary signal is generated, there is a problem that appropriate balance tuning cannot be performed. As a result, there is a problem that the performance of the gyro sensor varies.

Means for Solving the Problems

[0005] A method for manufacturing a physical quantity detection device is a method for manufacturing a physical quantity detection device including a physical quantity detection element including a base portion and a plurality of vibrating arms connected to the base portion, a detection circuit for detecting a detection vibration generated in the physical quantity detection element, and a drive circuit for driving the vibrating arms to vibrate. The vibrating arms include a first drive vibrating arm having a first weight portion at the tip, a second drive vibrating arm having a second weight portion at the tip, a first detection vibrating arm including a first detection electrode and a second detection electrode, a third detection electrode disconnected from both the first detection electrode and the second detection electrode, and a fourth detection electrode disconnected from both the first detection electrode and the second detection electrode. The method includes a first step of preparing the physical quantity detection element, a second step of adjusting at least one of the first drive vibrating arm and the second drive vibrating arm, and a third step of electrically connecting the first detection electrode and the third detection electrode and electrically connecting the second detection electrode and the fourth detection electrode.

[0006] A physical quantity detection device is a physical quantity detection device including a physical quantity detection element including a base portion and a plurality of vibrating arms connected to the base portion, a detection circuit for detecting a detection vibration generated in the physical quantity detection element, and a drive circuit for driving the vibrating arms to vibrate. The vibrating arms include a first drive vibrating arm having a first weight portion at the tip, a second drive vibrating arm having a second weight portion at the tip, a first detection vibrating arm including a first detection electrode and a second detection electrode, a second detection vibrating arm including a third detection electrode and a fourth detection electrode. The first detection electrode and the third detection electrode are electrically connected by a first conductive member, and the second detection electrode and the fourth detection electrode are electrically connected by a second conductive member. At least one of the first weight portion and the second weight portion has a processing mark recessed in the thickness direction.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 6C

Figure 6D

Figure 6E

Figure 6F

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0008] In the following figures, three mutually orthogonal axes will be described as the X-axis, Y-axis, and Z-axis. Also, the direction along the X-axis is the "X direction", the direction along the Y-axis is the "Y direction", the direction along the Z-axis is the "Z direction", the direction of the arrow is the + direction, and the direction opposite to the + direction is the - direction. Note that the plan view from the thickness direction of the vibration element 100, that is, the Z-axis direction, is also simply referred to as the "plan view".

[0009] As shown in FIG. 1, the physical quantity detection device 400 includes a vibration element 100 as a physical quantity detection element, a drive circuit 440 for driving the drive vibration arms 220, 222, 224, 226 (see FIG. 2) of the vibration element 100 to perform drive vibration, and a detection circuit 450 for detecting the detection vibration generated in the detection vibration arms 230, 232 of the vibration element 100 when an angular velocity is applied. The drive circuit 440 and the detection circuit 450 may be implemented by a single-chip IC, or may be implemented by separate IC chips respectively.

[0010] The drive circuit 440 includes an I / V conversion circuit (current-voltage conversion circuit) 441, an AC amplifier circuit 442, and an amplitude adjustment circuit 443. The drive circuit 440 is a circuit that outputs a signal for driving the drive vibration arms 220, 222, 224, 226 to the drive input electrode 30 (see FIG. 2) of the vibration element 100 and receives a signal output from the drive output electrode 32 (see FIG. 2) of the vibration element 100.

[0011] When the drive vibration arms 220, 222, 224, 226 of the vibration element 100 vibrate, an alternating current based on the piezoelectric effect is output from the drive output electrode 32 and input to the I / V conversion circuit 441. The I / V conversion circuit 441 converts the input alternating current into an alternating voltage signal having the same frequency as the vibration frequency of the drive vibration arms 220, 222, 224, 226 and outputs it.

[0012] The alternating voltage signal output from the I / V conversion circuit 441 is input to the AC amplifier circuit 442. The AC amplifier circuit 442 amplifies the input alternating voltage signal and outputs it.

[0013] The alternating voltage signal output from the AC amplifier circuit 442 is input to the amplitude adjustment circuit 443. The amplitude adjustment circuit 443 controls the gain so as to maintain the amplitude of the input alternating voltage signal at a constant value, and outputs the alternating voltage signal after gain control to the drive input electrode 30 of the vibration element 100. The drive vibration arms 220, 222, 224, 226 vibrate by the alternating voltage signal (drive signal) input to the drive input electrode 30.

[0014] The detection circuit 450 includes a charge amplifier 451 as a first amplifier, a charge amplifier 452 as a second amplifier, a differential amplifier circuit 453, an AC amplifier circuit 454, a synchronous detection circuit 455, a smoothing circuit 456, a variable amplifier circuit 457, and a filter circuit 458.

[0015] The detection circuit 450 is a circuit that detects an angular velocity based on signals respectively output from the first detection electrode 40, the second detection electrode 42, the third detection electrode 44, and the fourth detection electrode 46 (see FIGS. 2 and 3) of the vibration element 100.

[0016] The charge amplifier 451 includes an operational amplifier, a feedback resistor, and a feedback capacitor. The first detection signal (alternating current) output from the first detection electrode 40 and the third detection signal (alternating current) output from the third detection electrode 44 are input to the inverting input terminal (- terminal) of the operational amplifier. The non-inverting input terminal (+ terminal) of the operational amplifier is fixed to a reference potential. The first detection signal and the third detection signal are signals having the same electrical polarity. The charge amplifier 451 converts the first detection signal (alternating current) and the third detection signal (alternating current) input to the operational amplifier into an alternating voltage signal.

[0017] The charge amplifier 452 includes an operational amplifier, a feedback resistor, and a feedback capacitor. The second detection signal (alternating current) output from the second detection electrode 42 and the fourth detection signal (alternating current) output from the fourth detection electrode 46 are input to the inverting input terminal (- terminal) of the operational amplifier. The non-inverting input terminal (+ terminal) of the operational amplifier is fixed to a reference potential. The second detection signal and the fourth detection signal are signals having the same electrical polarity. The charge amplifier 452 converts the second detection signal (alternating current) and the fourth detection signal (alternating current) input to the operational amplifier into an alternating voltage signal.

[0018] Note that the first detection signal and the third detection signal, and the second detection signal and the fourth detection signal have opposite electrical characteristics. The output signal of the charge amplifier 451 and the output signal of the charge amplifier 452 are input to the differential amplifier circuit 453.

[0019] The differential amplifier circuit 453 functions as a differential amplification unit that differentially amplifies the output signal of the vibration element 100. The differential amplifier circuit 453 outputs a signal obtained by amplifying (differentially amplifying) the potential difference between the output signal of the charge amplifier 451 and the output signal of the charge amplifier 452. The output signal of the differential amplifier circuit 453 is input to the AC amplifier circuit 454.

[0020] The AC amplifier circuit 454 functions as an AC amplification unit that amplifies an AC signal, and outputs a signal obtained by amplifying the output signal of the differential amplifier circuit 453. The output signal of the AC amplifier circuit 454 is input to the synchronous detection circuit 455.

[0021] The synchronous detection circuit 455 extracts an angular velocity component by synchronously detecting the output signal of the AC amplifier circuit 454 based on the AC voltage signal output by the AC amplifier circuit 442 of the drive circuit 440. The signal of the angular velocity component extracted by the synchronous detection circuit 455 is smoothed into a DC voltage signal by the smoothing circuit 456 and input to the variable amplification circuit 457.

[0022] The variable amplification circuit 457 amplifies (or attenuates) the output signal (DC voltage signal) of the smoothing circuit 456 at a set amplification factor (or attenuation factor) to change the angular velocity sensitivity. The signal amplified (or attenuated) by the variable amplification circuit 457 is input to the filter circuit 458.

[0023] The filter circuit 458 removes high-frequency noise components outside the sensor band from the output signal of the variable amplification circuit 457 (accurately attenuates them to a predetermined level or below), and outputs a detection signal with a polarity and voltage level corresponding to the direction and magnitude of the angular velocity. This detection signal is output to the outside from an external output terminal (not shown).

[0024] Note that, in the physical quantity detection device 400 of FIG. 1, although a configuration example of an analog gyro sensor that outputs the detected angular velocity as an analog voltage (DC voltage) is shown, the present embodiment is not limited to this. For example, instead of the smoothing circuit 456, variable amplification circuit 457, and filter circuit 458 at a stage subsequent to the synchronous detection circuit 455, an A / D conversion circuit and a DSP unit (digital signal processing unit) may be provided to form a digital gyro sensor that outputs the detected angular velocity as digital data. In this case, the A / D conversion circuit performs A / D conversion on the signal after synchronous detection and outputs a digital signal, and the DSP unit performs digital signal processing such as digital filter processing and digital correction processing on the digital signal from the A / D conversion circuit and outputs a digital signal corresponding to the detected angular velocity. Further, a filter unit such as a low-pass filter may be provided between the synchronous detection circuit 455 and the A / D conversion circuit. This filter unit has a function as a pre-filter for the A / D conversion circuit and a function of attenuating unnecessary signals that could not be completely removed by the synchronous detection circuit.

[0025] Next, with reference to FIGS. 2 and 3, the configuration of the vibration element 100 will be described.

[0026] As shown in FIG. 2, the vibration element 100 includes a base 10, connecting arms 210, 212, drive vibration arms 220, 222, 224, 226, and detection vibration arms 230, 232. The vibration element 100 also includes support portions 240, 242, beam portions 250, 252, 254, 256, a drive input electrode 30, a drive output electrode 32, a first detection electrode 40, a second detection electrode 42, a third detection electrode 44, and a fourth detection electrode 46. The vibration element 100 further includes a drive input wiring 50, a drive output wiring 52, a first detection wiring 60, a second detection wiring 62, a third detection wiring 64, and a fourth detection wiring 66.

[0027] The base 10, connecting arms 210, 212, drive vibration arms 220, 222, 224, 226, detection vibration arms 230, 232, support portions 240, 242, and beam portions 250, 252, 254, 256 constitute the vibration piece 1.

[0028] The material of the vibrating piece 1 is a piezoelectric material such as quartz, lithium tantalate, or lithium niobate, for example. The vibrating piece 1 has a first main surface 2a and a second main surface 2b facing in opposite directions, and side surfaces 3 connected to the main surfaces 2a and 2b. In the illustrated example, the first main surface 2a is a surface facing in the +Z-axis direction, the second main surface 2b is a surface facing in the -Z-axis direction, and the side surfaces 3 are surfaces whose perpendiculars are orthogonal to the Z-axis. The main surfaces 2a and 2b are, for example, flat surfaces. The thickness (the dimension in the Z-axis direction) of the vibrating piece 1 is, for example, about 100 μm.

[0029] The planar shape of the base 10 is, for example, rectangular (substantially rectangular). The first connecting arm 210 and the second connecting arm 212 extend from the base 10 in opposite directions along the X-axis. In the illustrated example, the first connecting arm 210 extends from the base 10 in the -X-axis direction. The second connecting arm 212 extends from the base 10 in the +X-axis direction.

[0030] The driving vibrating arms 220 and 222 as the first driving vibrating arms extend from the first connecting arm 210 in opposite directions along the Y-axis. In the illustrated example, the driving vibrating arm 220 extends from the first connecting arm 210 in the +Y-axis direction. The driving vibrating arm 222 extends from the first connecting arm 210 in the -Y-axis direction. The driving vibrating arms 220 and 222 are connected to the base 10 via the first connecting arm 210.

[0031] The driving vibrating arms 224 and 226 as the second driving vibrating arms extend from the second connecting arm 212 in opposite directions along the Y-axis. In the illustrated example, the driving vibrating arm 224 extends from the second connecting arm 212 in the +Y-axis direction. The driving vibrating arm 226 extends from the second connecting arm 212 in the -Y-axis direction. The driving vibrating arms 224 and 226 are connected to the base 10 via the second connecting arm 212.

[0032] The first detection vibrating arm 230 and the second detection vibrating arm 232 extend from the base 10 in opposite directions along the Y-axis. In the illustrated example, the first detection vibrating arm 230 extends from the base 10 in the +Y-axis direction. The second detection vibrating arm 232 extends from the base 10 in the -Y-axis direction. The detection vibrating arms 230 and 232 are connected to the base 10.

[0033] At the tips of the vibrating arms 220, 222, 224, 226, 230, and 232, a wide portion 5 is provided. The wide portion 5 has a greater width (size in the X-axis direction) than the other portions of the vibrating arms 220, 222, 224, 226, 230, and 232. Although not shown, a weight portion is provided on the wide portion 5. By adjusting the mass of the weight portion, the vibration frequency of the vibrating arms 220, 222, 224, 226, 230, and 232 can be adjusted.

[0034] The first support portion 240 is provided on the +Y-axis side of the vibrating arms 220, 224, and 230. The second support portion 242 is provided on the -Y-axis side of the vibrating arms 222, 226, and 232. The support portions 240 and 242 are the portions fixed to the package when the vibration element 100 is mounted. The support portions 240 and 242 support the base 10 via the beam portions 250, 252, 254, and 256.

[0035] The first beam portion 250 and the second beam portion 252 connect the base 10 and the first support portion 240. In the illustrated example, the first beam portion 250 extends from the base 10 through the space between the drive vibrating arm 220 and the first detection vibrating arm 230 to the first support portion 240. The second beam portion 252 extends from the base 10 through the space between the drive vibrating arm 224 and the first detection vibrating arm 230 to the first support portion 240.

[0036] The third beam portion 254 and the fourth beam portion 256 connect the base portion 10 and the second support portion 242. In the illustrated example, the third beam portion 254 extends from the base portion 10 through between the drive vibration arms 222 and the second detection vibration arm 232 to the second support portion 242. The fourth beam portion 256 extends from the base portion 10 through between the drive vibration arm 226 and the second detection vibration arm 232 to the second support portion 242.

[0037] In the vibration element 100 of the present embodiment, as shown in FIG. 2, the vibration piece 1 is a so-called double T-shaped vibration piece.

[0038] As the drive input electrode 30, the drive output electrode 32, the first detection electrode 40, the second detection electrode 42, the third detection electrode 44, the fourth detection electrode 46, the drive input wiring 50, the drive output wiring 52, the first detection wiring 60, the second detection wiring 62, the third detection wiring 64, and the fourth detection wiring 66, for example, those laminated in the order of chromium and gold from the vibration piece 1 side are used.

[0039] The drive input electrode 30 is provided on the drive vibration arms 220, 222, 224, 226. In the illustrated example, the drive input electrode 30 is provided on the side surface 3 of the drive vibration arm 220, the side surface 3 of the drive vibration arm 222, the side surfaces 3 of the connecting arms 210, 212, the main surfaces 2a, 2b of the drive vibration arm 224, and the main surfaces 2a, 2b of the drive vibration arm 226. The drive input electrode 30 is an electrode to which a signal (drive signal) for driving the drive vibration arms 220, 222, 224, 226 is input.

[0040] The drive output electrode 32 is provided on the main surfaces 2a, 2b of the drive vibration arm 220, the main surfaces 2a, 2b of the drive vibration arm 222, the side surface 3 of the drive vibration arm 224, and the side surface 3 of the drive vibration arm 226. The drive output electrode 32 is an electrode for outputting a signal based on the bending of the drive vibration arms 220, 222, 224, 226.

[0041] Note that the drive output electrode 32 may be provided at the position where the drive input electrode 30 is provided, or the drive input electrode 30 may be provided at the position where the drive output electrode 32 is provided.

[0042] The first detection electrode 40 is provided on the first detection vibrating arm 230. In the illustrated example, the first detection electrode 40 is provided on the main surfaces 2a and 2b of the first detection vibrating arm 230. The first detection electrode 40 is an electrode for detecting a signal (first detection signal) based on the bending of the first detection vibrating arm 230 due to the Coriolis force.

[0043] The second detection electrode 42 is provided on the first detection vibrating arm 230. In the illustrated example, the second detection electrode 42 is provided on the side surface 3 and the wide portion 5 of the first detection vibrating arm 230. The second detection electrode 42 is an electrode for detecting a signal (second detection signal) based on the bending of the first detection vibrating arm 230 due to the Coriolis force.

[0044] The third detection electrode 44 is provided on the second detection vibrating arm 232. In the illustrated example, the third detection electrode 44 is provided on the side surface 3 and the wide portion 5 of the second detection vibrating arm 232. The third detection electrode 44 is an electrode for detecting a signal (third detection signal) based on the bending of the second detection vibrating arm 232 due to the Coriolis force.

[0045] The fourth detection electrode 46 is provided on the second detection vibrating arm 232. In the illustrated example, the fourth detection electrode 46 is provided on the main surfaces 2a and 2b of the second detection vibrating arm 232. The fourth detection electrode 46 is an electrode for detecting a signal (fourth detection signal) based on the bending of the second detection vibrating arm 232 due to the Coriolis force.

[0046] Although not shown, the drive input wiring 50 is provided on the base 10, the connecting arms 210 and 212, the second support portion 242, and the third beam portion 254. The drive input electrodes 30 provided on the vibrating arms 220, 222, 224, and 226 are electrically connected to each other by the drive input wiring 50. The drive input wiring 50 provided on the second support portion 242 is the terminal portion 50a. The terminal portion 50a is connected to an external member (for example, a bonding wire). The drive signal output from the drive circuit 440 is input to the drive input electrode 30 via the external member and the drive input wiring 50.

[0047] The drive output wiring 52 is provided on the base 10, the connecting arms 210, 212, the first support portion 240, and the first beam portion 250. The drive output electrodes 32 provided on the vibrating arms 220, 222, 224, 226 are electrically connected to each other by the drive output wiring 52. The drive output wiring 52 provided on the first support portion 240 is the terminal portion 52a. The terminal portion 52a is connected to an external member (for example, a bonding wire). The signal output from the drive output electrode 32 is input to the drive circuit 440 via the drive output wiring 52 and the external member.

[0048] The first detection wiring 60 is provided on the base 10, the first support portion 240, and the second beam portion 252. The first detection wiring 60 is connected to the first detection electrode 40. The first detection wiring 60 provided on the first support portion 240 is the terminal portion 60a. The terminal portion 60a is connected to an external member (for example, a bonding wire). The first detection signal output from the first detection electrode 40 is input to the charge amplifier 451 of the detection circuit 450 via the first detection wiring 60 and the external member.

[0049] The second detection wiring 62 is provided on the base 10, the first support portion 240, and the second beam portion 252. The second detection wiring 62 is connected to the second detection electrode 42. The second detection wiring 62 provided on the first support portion 240 is the terminal portion 62a. The terminal portion 62a is connected to an external member (for example, a bonding wire). The second detection signal output from the second detection electrode 42 is input to the charge amplifier 452 of the detection circuit 450 via the second detection wiring 62 and the external member.

[0050] The third detection wiring 64 is provided on the base 10, the second support portion 242, and the fourth beam portion 256. The third detection wiring 64 is connected to the third detection electrode 44. The third detection wiring 64 provided on the second support portion 242 is the terminal portion 64a. The terminal portion 64a is connected to an external member (for example, a bonding wire). The third detection signal output from the third detection electrode 44 is input to the charge amplifier 451 of the detection circuit 450 via the third detection wiring 64 and the external member.

[0051] The fourth detection wiring 66 is provided on the base 10, the second support portion 242, and the fourth beam portion 256. The fourth detection wiring 66 is connected to the fourth detection electrode 46. The fourth detection wiring 66 provided on the second support portion 242 is the terminal portion 66a. The terminal portion 66a is connected to an external member (for example, a bonding wire). The fourth detection signal output from the fourth detection electrode 46 is input to the charge amplifier 452 of the detection circuit 450 via the fourth detection wiring 66 and the external member.

[0052] As shown in FIG. 3, the first detection electrode 40 and the third detection electrode 44 are electrically connected by the first conductive member 1010. The second detection electrode 42 and the fourth detection electrode 46 are electrically connected by the second conductive member 1020.

[0053] Before the first conductive member 1010 is formed, the first detection electrode 40 and the third detection electrode 44 are disconnected. Before the second conductive member 1020 is formed, the second detection electrode 42 and the fourth detection electrode 46 are disconnected.

[0054] That is, since the third detection electrode 44 and the fourth detection electrode 46 are disconnected from both the first detection electrode 40 and the second detection electrode 42, the detection vibrations of the two detection vibrating arms 230 and 232 can be detected individually, in other words, measured. Therefore, the adjustment of the driving vibrating arms 220, 222, 224, and 226, that is, the balance tuning can be appropriately performed. Thereby, it is possible to suppress variations in the performance of the physical quantity detection device 400.

[0055] Also, after performing the balance tuning, by electrically connecting the first detection electrode 40 and the third detection electrode 44 with the first conductive member 1010 and electrically connecting the second detection electrode 42 and the fourth detection electrode 46 with the second conductive member 1020, the amount of charge (current amount) input to the detection circuit 450 increases, so that the element sensitivity (angular velocity detection sensitivity) of the vibration element 100 can be improved.

[0056] As a result, the S / N of the output signal of the detection circuit 450 is improved, and low noise can be achieved. Also, by increasing the element sensitivity, the temperature characteristics of the output signal of the detection circuit 450 also appear relatively small. Therefore, it is possible to provide the physical quantity detection device 400 capable of improving the vibration characteristics.

[0057] Next, with reference to FIG. 4, the connection configuration between the vibration element 100 and the charge amplifiers 451 and 452 will be described. The upper diagram of FIG. 4 is a cross-sectional view along the B-B line of the vibration element 100 in FIG. 2, and the lower diagram of FIG. 4 is a cross-sectional view along the C-C line of the vibration element in FIG. 2.

[0058] Also, with reference to FIGS. 6A to 6F, the signal waveforms in the detection mode will be described. FIG. 6A is the signal waveform of the first detection signal output from the terminal portion 60a. FIG. 6B is the signal waveform of the second detection signal output from the terminal portion 62a. FIG. 6C is the signal waveform of the third detection signal output from the terminal portion 64a. FIG. 6D is the signal waveform of the fourth detection signal output from the terminal portion 66a. FIG. 6E is the signal waveform of the input signal of the charge amplifier 451, that is, the sum signal of the first detection signal and the third detection signal. FIG. 6F is the signal waveform of the input signal of the charge amplifier 452, that is, the sum signal of the second detection signal and the fourth detection signal.

[0059] As shown in FIG. 4, groove portions are provided on the main surfaces 2a and 2b of the vibrating arms 230 and 232. The electrodes 40 and 46 are provided in the groove portions. Although not shown, groove portions may also be provided on the main surfaces 2a and 2b of the vibrating arms 220, 222, 224, and 226. The electrodes 30 and 32 may also be provided in the groove portions.

[0060] In the physical quantity detection device 400, both the terminal portion 60a and the terminal portion 64a of the vibration element 100 are connected to the inverting input terminal (- terminal) of the operational amplifier provided in the charge amplifier 451.

[0061] As shown in FIGS. 6A to 6F, the input signal of the charge amplifier 451 is a signal obtained by adding the first detection signal and the third detection signal. The first detection signal and the third detection signal are signals having the same electrical polarity (in-phase). The amplitude of the input signal of the charge amplifier 451 is approximately equal to the sum of the amplitude of the first detection signal and the amplitude of the third detection signal.

[0062] Similarly, both the terminal portion 62a and the terminal portion 66a of the vibrating element 100 are connected to the inverting input terminal (- terminal) of the operational amplifier provided in the charge amplifier 452.

[0063] The input signal of the charge amplifier 452 is a signal obtained by adding the second detection signal and the fourth detection signal. Since the second detection signal and the fourth detection signal are signals having the same electrical polarity (in-phase), the amplitude of the input signal of the charge amplifier 452 is approximately equal to the sum of the amplitude of the second detection signal and the amplitude of the fourth detection signal.

[0064] The sum signal of the first detection signal and the third detection signal (that is, the input signal of the charge amplifier 451) and the sum signal of the second detection signal and the fourth detection signal (that is, the input signal of the charge amplifier 452) are in a relationship of opposite electrical polarity (anti-phase).

[0065] According to the physical quantity detection device 400 of the present embodiment, compared with the conventional physical quantity detection device, when the vibrating element 100 detects the same angular velocity, the amount of charge (current amount) input to the detection circuit 450 increases, so the element sensitivity (detection sensitivity of angular velocity) of the vibrating element 100 is improved.

[0066] As a result, the S / N of the output signal of the detection circuit 450 is improved, and low noise can be achieved. In addition, by increasing the element sensitivity, the temperature characteristics of the output signal of the detection circuit 450 also appear to be relatively small. Therefore, according to the present embodiment, a highly accurate and highly stable physical quantity detection device 400 can be realized.

[0067] Note that since the first detection electrode 40 and the third detection electrode 44 are connected to the inverting input terminal (- terminal) of the operational amplifier provided in the charge amplifier 451, they are virtually short-circuited with the non-inverting input terminal (+ terminal) of this operational amplifier and always have the reference potential.

[0068] Similarly, since the second detection electrode 42 and the fourth detection electrode 46 are connected to the inverting input terminal (- terminal) of the operational amplifier provided in the charge amplifier 452, they are virtually short-circuited with the non-inverting input terminal (+ terminal) of this operational amplifier and always have the reference potential.

[0069] That is, in the present embodiment, the first detection electrode 40, the second detection electrode 42, the third detection electrode 44, and the fourth detection electrode 46 always have the same potential, and no electric field is generated between the electrodes.

[0070] The driving vibrating arms 220, 222, 224, 226 have a resonance frequency fdr determined by their length, thickness, material, etc., and the detection vibrating arms 230, 232 have a resonance frequency fdt determined by their length, thickness, material, etc. The difference between this resonance frequency fdr and fdt is called the detuning frequency.

[0071] Next, with reference to FIGS. 5A and 5B, the operation of the vibration element 100 will be described. Note that in FIGS. 5A and 5B, illustration of members other than the base 10, the connecting arms 210, 212, and the vibrating arms 220, 222, 224, 226, 230, 232 is omitted.

[0072] As shown in FIG. 5A, when a predetermined alternating voltage is applied to the drive input electrodes 30 provided on the driving vibrating arms 220, 222, 224, 226 in a state where no angular velocity is applied, the vibration element 100 performs bending vibration in the direction of arrow A in the XY plane. At this time, the driving vibrating arms 220, 222 and the driving vibrating arms 224, 226 perform vibration that is symmetric with respect to a plane passing through the center point G and parallel to the YZ plane. Therefore, the base 10, the connecting arms 210, 212, and the detection vibrating arms 230, 232 hardly vibrate.

[0073] When the driving vibrating arms 220, 222, 224, 226 are performing such driving vibrations, as shown in FIG. 5B, when an angular velocity ω about the Z-axis is applied to the vibrating element 100, a Coriolis force acts on the driving vibrating arms 220, 222, 224, 226. As a result, the driving vibrating arms 220, 222, 224, 226 vibrate in the direction of arrow B. The vibration in the direction of arrow B is a circumferential vibration with respect to the center point G.

[0074] Then, due to the vibration of the driving vibrating arms 220, 222, 224, 226, the connecting arms 210, 212 vibrate in the direction of arrow B. This vibration is transmitted to the detection vibrating arms 230, 232 via the base 10, causing the detection vibrating arms 230, 232 to vibrate as shown by arrow C. The vibration in the direction of arrow C is a vibration in the circumferential direction opposite to that of arrow B with respect to the center point G.

[0075] Due to the bending vibration of the detection vibrating arms 230, 232, a first detection signal, a second detection signal, a third detection signal, and a fourth detection signal are generated in the first detection electrode 40, the second detection electrode 42, the third detection electrode 44, and the fourth detection electrode 46, respectively.

[0076] At this time, the electrical polarities of the first detection signal and the second detection signal are opposite, and the electrical polarities of the third detection signal and the fourth detection signal are opposite. Also, the electrical polarities of the first detection signal and the third detection signal are the same, and the electrical polarities of the second detection signal and the fourth detection signal are the same.

[0077] For example, when a positive charge δ+ is generated in the first detection electrode 40 and the third detection electrode 44, a negative charge δ- is generated in the second detection electrode 42 and the fourth detection electrode 46. When a negative charge δ- is generated in the first detection electrode 40 and the third detection electrode 44, a positive charge δ+ is generated in the second detection electrode 42 and the fourth detection electrode 46.

[0078] The first detection signal, the second detection signal, the third detection signal, and the fourth detection signal are output from the terminal portions 60a, 62a, 64a, and 66a to the detection circuit 450, respectively. The detection circuit 450 can obtain the angular velocity around the Z axis based on these detection signals.

[0079] Hereinafter, as shown in FIG. 5A, a state where the angular velocity is not detected is referred to as a "driving mode", and as shown in FIG. 5B, a state where the angular velocity is detected is referred to as a "detection mode".

[0080] Next, a manufacturing method of the physical quantity detection device 400 will be described with reference to FIGS. 7 to 9.

[0081] As shown in FIG. 7, in step S11 (the first step), a vibration element 100 as a physical quantity detection element is prepared. As shown in FIG. 3, the vibration element 100 has a first detection electrode 40, a second detection electrode 42, a third detection electrode 44, and a fourth detection electrode 46 formed on the base portion 10.

[0082] As shown in FIG. 8, the third detection electrode 44 is disconnected from both the first detection electrode 40 and the second detection electrode 42. Similarly, the fourth detection electrode 46 is disconnected from both the first detection electrode 40 and the second detection electrode 42.

[0083] In step S12, the vibration element 100 is mounted on a package (not shown). Specifically, the support portions 240 and 242 of the vibration element 100 are fixed to the package. Note that it is not limited to a package, and it may be mounted on a support substrate or an intermediate substrate.

[0084] In step S13, the outputs from the detection electrodes 40, 42, 44, and 46 are measured. Specifically, the signals output from the first detection electrode 40 and the third detection electrode 44 via the charge amplifier 451, that is, the detection vibration, and the signals output from the second detection electrode 42 and the fourth detection electrode 46 via the charge amplifier 452, that is, the detection vibration, are measured.

[0085] In step S14 (second process), at least one of the drive vibrating arms 220, 222, 224, 226 is adjusted, that is, balance tuning is performed. Specifically, a weight (not shown) as the first weight portion provided in the wide portion 5 of the drive vibrating arms 220, 222 is adjusted, and a weight (not shown) as the second weight portion provided in the drive vibrating arms 224, 226 is adjusted (see FIG. 2).

[0086] Adjustment means changing the mass of the weight portion. Specifically, for example, an energy beam such as a laser is irradiated onto a gold film of about 1 μm formed on the weight portion to remove a part of the gold film. By removing the gold film, the frequency becomes higher. In addition, a method of adding a gold film by performing sputtering or vapor deposition using a metal mask to lower the frequency may be used.

[0087] In balance tuning, while measuring the detection signal generated by unnecessary vibration, the mass of the weight portions provided on each of the drive vibrating arms 220, 222, 224, 226 is changed and adjusted to reduce unnecessary vibration. Further, in balance tuning, unnecessary signals generated from the two detection vibrating arms 230, 232 are measured separately, and the processing amount of the drive vibrating arms 220, 222, 224, 226 is calculated according to the measured values.

[0088] As shown in FIG. 8, the electrodes capable of measuring the unnecessary signal are, for example, the first detection electrode 40 and the fourth detection electrode 46. Also, by looking at the laser marks (processing marks) of each of the drive vibrating arms 220, 222, 224, 226, it is possible to determine whether balance tuning has been performed.

[0089] Thus, since the mass of the weight portion is changed, it becomes possible to adjust the frequency generated by the drive vibrating arms 220, 222, 224, 226, and it is possible to suppress the unnecessary signal from being detected by the first detection vibrating arm 230 and the second detection vibrating arm 232.

[0090] In addition, since balance tuning is performed after mounting the vibration element 100 on the package and the support substrate, a more reliable physical quantity detection device 400 can be provided.

[0091] Further, since the detected vibration is measured via the charge amplifiers 451 and 452 (see FIG. 4), even a slight unwanted signal detected by the detection electrodes 40, 42, 44, and 46 can be surely measured.

[0092] In step S15 (the third step), as shown in FIG. 9, the first detection electrode 40 and the third detection electrode 44 are electrically connected, and the second detection electrode 42 and the fourth detection electrode 46 are electrically connected. Specifically, they are electrically connected by adding the conductive members 1010 and 1020. More specifically, the first detection electrode 40 and the third detection electrode 44 are electrically connected via the first conductive member 1010. The second detection electrode 42 and the fourth detection electrode 46 are electrically connected via the second conductive member 1020.

[0093] Examples of the connection method include an inkjet method, a coating method, and a bonding method. The inkjet method is an electrostatic inkjet or a piezo inkjet, which ejects a conductive ink or a conductive paste. The coating method coats a conductive adhesive. The bonding method is wire bonding or bump bonding.

[0094] In this way, since the third detection electrode 44 and the fourth detection electrode 46 are disconnected from both the first detection electrode 40 and the second detection electrode 42, the detected vibrations of the two detection vibration arms 230 and 232 can be individually detected, in other words, measured. Therefore, the adjustment of the drive vibration arms 220, 222, 224, and 226, that is, the balance tuning can be appropriately performed. Thereby, it is possible to suppress variations in the performance of the physical quantity detection device 400. Further, after performing the balance tuning, since the positive electrodes and the negative electrodes are electrically connected to each other at the detection electrodes 40, 42, 44, and 46, it is possible to provide the physical quantity detection device 400 capable of improving the sensitivity of the vibration characteristics.

[0095] As described above, the method for manufacturing the physical quantity detection device 400 according to the present embodiment includes a vibration element 100 including a base portion 10 and a plurality of vibration arms 220, 222, 224, 226, 230, 232 connected to the base portion 10, a detection circuit 450 that detects a detection vibration generated in the vibration element 100, and a drive circuit 440 that drives the vibration arms 220, 222, 224, 226, 230, 232 to vibrate. The vibration arms 220, 222, 224, 226, 230, 232 include drive vibration arms 220, 222 having a weight portion at the tip, drive vibration arms 224, 226 having a weight portion at the tip, a first detection vibration arm 230 including a first detection electrode 40 and a second detection electrode 42, a third detection electrode 44 that is disconnected from both the first detection electrode 40 and the second detection electrode 42, and a fourth detection electrode 46 that is disconnected from both the first detection electrode 40 and the second detection electrode 42. The method includes a first step of preparing the vibration element 100, a second step of adjusting at least one of the drive vibration arms 220, 222, 224, 226, and a third step of electrically connecting the first detection electrode 40 and the third detection electrode 44 and electrically connecting the second detection electrode 42 and the fourth detection electrode 46.

[0096] According to this method, since the third detection electrode 44 and the fourth detection electrode 46 are disconnected from both the first detection electrode 40 and the second detection electrode 42, the detection vibrations of the two detection vibration arms 230, 232 can be detected individually, in other words, measured. Therefore, the adjustment of the drive vibration arms 220, 222, 224, 226, that is, the balance tuning can be appropriately performed. Thereby, it is possible to suppress variations in the performance of the physical quantity detection device 400.

[0097] Further, in the method for manufacturing the physical quantity detection device 400 according to the present embodiment, it is preferable that the adjustment changes the mass of at least one of the weight portions. According to this method, since the mass of the weight portion is changed, it is possible to adjust the frequency generated by the drive vibration arms 220, 222, 224, 226, and it is possible to suppress the detection of unnecessary signals by the first detection vibration arm 230 and the second detection vibration arm 232.

[0098] Also, in the manufacturing method of the physical quantity detection device 400 according to the present embodiment, a charge amplifier 451 as a first amplifier to which the outputs from the first detection electrode 40 and the third detection electrode 44 are input, and a charge amplifier 452 as a second amplifier to which the outputs from the second detection electrode 42 and the fourth detection electrode 46 are input are provided. Before the second step, it is preferable to measure the detection vibration via the charge amplifiers 451 and 452. According to this method, since the detection vibration is measured via the charge amplifiers 451 and 452, even a slight unnecessary signal detected by the detection electrodes 40, 42, 44, and 46 can be surely measured.

[0099] Also, in the manufacturing method of the physical quantity detection device 400 according to the present embodiment, it is preferable that the second step is performed after mounting the vibration element 100 on the package or the support substrate. According to this method, since the balance tuning is performed after mounting the vibration element 100 on the package or the support substrate, a more reliable physical quantity detection device 400 can be provided.

[0100] Also, in the manufacturing method of the physical quantity detection device 400 according to the present embodiment, in the third step, it is preferable to electrically connect by adding the conductive members 1010 and 1020. According to this method, after performing the balance tuning, the first detection electrode 40 and the third detection electrode 44 are electrically connected, and the second detection electrode 42 and the fourth detection electrode 46 are electrically connected, that is, the positive electrodes are electrically connected to each other and the negative electrodes are electrically connected to each other. Therefore, a physical quantity detection device 400 capable of improving the sensitivity of the vibration characteristics can be provided.

[0101] Also, in the manufacturing method of the physical quantity detection device 400 according to the present embodiment, the vibration element 100 is preferably a double-T type gyro sensor element. According to this method, a physical quantity detection device 400 including a double-T type gyro sensor element capable of improving the vibration characteristics can be provided.

[0102] Further, the physical quantity detection device 400 of the present embodiment includes a vibration element 100 including a base portion 10 and a plurality of vibration arms 220, 222, 224, 226, 230, 232 connected to the base portion 10, a detection circuit 450 that detects a detection vibration generated in the vibration element 100, and a drive circuit 440 that drives the vibration arms 220, 222, 224, 226, 230, 232 to vibrate. The vibration arms 220, 222, 224, 226, 230, 232 include drive vibration arms 220, 222, 224, 226 having a weight portion at the tip, a first detection vibration arm 230 including a first detection electrode 40 and a second detection electrode 42, and a second detection vibration arm 232 including a third detection electrode 44 and a fourth detection electrode 46. The first detection electrode 40 and the third detection electrode 44 are electrically connected by a first conductive member 1010, and the second detection electrode 42 and the fourth detection electrode 46 are electrically connected by a second conductive member 1020. At least one of the weight portions has a processing mark recessed in the thickness direction.

[0103] According to this configuration, since the processing mark recessed in the weight portion is formed and the detection electrodes 40, 42, 44, 46 are connected by the first conductive member 1010 and the second conductive member 1020, adjustment of the drive vibration arms 220, 222, 224, 226, that is, balance tuning is performed, and the sensitivity of the detection vibration arms 230, 232 can be improved. That is, variations in the performance of the physical quantity detection device 400 can be suppressed, and the vibration characteristics can be improved. Further, it can be confirmed that balance tuning has been performed due to the processing marks on the tip weight portions of the drive vibration arms 220, 222, 224, 226.

[0104] Hereinafter, modifications of the above-described embodiment will be described.

[0105] As described above, the vibrating piece 1 is not limited to being a double-T type gyro sensor, and may be an H type gyro sensor. Hereinafter, with reference to FIGS. 10 and 11, the configuration of the gyro sensor of the modified example will be described. Note that FIG. 10 is a view of the vibrating element 100A of the modified example as seen from the first main surface 2a side. Further, FIG. 11 also shows the connection relationship between the vibrating element 100 and the charge amplifiers 451 and 452. In addition, in FIGS. 10 and 11, members having the same functions as the constituent members of the vibrating element 100 of the above-described embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0106] As shown in FIG. 10, the vibrating element 100A of the modified example has a base portion 10, drive vibrating arms 220 and 222, detection vibrating arms 230 and 232, a support portion 240, and beam portions 250, 252, 254, and 256.

[0107] The first detection electrode 40 is provided on the second detection vibrating arm 232. In the illustrated example, the first detection electrode 40 is provided on the main surfaces 2a and 2b and the side surface 3 of the second detection vibrating arm 232.

[0108] The second detection electrode 42 is provided on the second detection vibrating arm 232. In the illustrated example, the second detection electrode 42 is provided on the main surfaces 2a and 2b and the side surface 3 of the second detection vibrating arm 232.

[0109] The third detection electrode 44 is provided on the first detection vibrating arm 230. In the illustrated example, the third detection electrode 44 is provided on the main surfaces 2a and 2b and the side surface 3 of the first detection vibrating arm 230.

[0110] The fourth detection electrode 46 is provided on the first detection vibrating arm 230. In the illustrated example, the fourth detection electrode 46 is provided on the main surfaces 2a and 2b and the side surface 3 of the first detection vibrating arm 230.

[0111] In this embodiment, as shown in FIG. 11, groove portions are provided on the main surfaces 2a of the vibrating arms 230 and 232. The cross section of the vibrating arms 230 and 232 is H-shaped. The electrodes 40, 42, 44, and 46 are provided in the groove portions and on the side surfaces 3. Although not shown, groove portions may also be provided on the main surfaces 2a of the vibrating arms 220 and 222, and the electrodes 30 and 32 may be provided in the groove portions.

[0112] Even in such a vibration element 100A, the outputs from the detection electrodes 40, 42, 44, and 46 are measured, and the balance tuning of the driving vibrating arms 220 and 222 is performed based on the measured signals. Thereafter, the first detection electrode 40 and the third detection electrode 44 are electrically connected via the first conductive member 1010, and the second detection electrode 42 and the fourth detection electrode 46 are electrically connected via the second conductive member 1020. Thereby, the sensitivity of the vibration characteristics can be improved.

[0113] As described above, in the method for manufacturing the physical quantity detection device 400 of the modification, the vibration element 100 is preferably an H-type gyro sensor element. According to this method, a physical quantity detection device 400 including an H-type gyro sensor element capable of improving vibration characteristics can be provided.

[0114] Also, as described above, the vibrating piece 1 is not limited to being a double-T type gyro sensor, and a physical quantity detection device 400 having a vibration element 100B shown in FIG. 12 may be used.

[0115] As shown in FIG. 12, the vibration element 100B of the modification has a base 10, driving vibrating arms 220, 222, 224, and 226, and detection vibrating arms 230 and 232.

[0116] The first detection electrode 40 is provided on the main surfaces 2a and 2b of the detection vibrating arm 230, respectively. The second detection electrode 42 is provided on the side surface 3 of the detection vibrating arm 230.

[0117] The third detection electrode 44 is provided on the side surface 3 of the detection vibrating arm 232. Further, the fourth detection electrode 46 is provided on the main surfaces 2a and 2b of the detection vibrating arm 232, respectively.

[0118] Even in such a vibration element 100B, the outputs from the detection electrodes 40, 42, 44, and 46 are measured, and the balance tuning of the drive vibrating arms 220, 222, 224, and 226 is performed based on the measured signals. Thereafter, the first detection electrode 40 and the third detection electrode 44 are electrically connected via the first conductive member 1010, and the second detection electrode 42 and the fourth detection electrode 46 are electrically connected via the second conductive member 1020. Thereby, the sensitivity of the vibration characteristics can be improved.

[0119] Also, as described above, the vibration element 100 is exemplified by a double T-type gyro sensor or an H-type gyro sensor, but it is not limited thereto, and it may be a silicon MEMS gyro sensor. Further, it is not limited to a gyro element, and for example, it may be a tuning fork type vibration element.

Explanation of reference numerals

[0120] 1…Vibrating piece, 2a…First main surface, 2b…Second main surface, 3…Side surface, 5…Wide portion, 10…Base portion, 30…Drive input electrode, 32…Drive output electrode, 40…First detection electrode, 42…Second detection electrode, 44…Third detection electrode, 46…Fourth detection electrode, 50…Drive input wiring, 50a…Terminal portion, 52…Drive output wiring, 52a…Terminal portion, 60…First detection wiring, 60a…Terminal portion, 62…Second detection wiring, 62a…Terminal portion, 64…Third detection wiring, 64a…Terminal portion, 66…Fourth detection wiring, 66a…Terminal portion, 100, 100A, 100B…Vibration element as a physical quantity detection element, 210…First connecting arm, 212…Second connecting arm, 220…Drive vibration arm as the first drive vibration arm, 222…Drive vibration arm as the first drive vibration arm, 224…Drive vibration arm as the second drive vibration arm, 226…Drive vibration arm as the second drive vibration arm, 230…First detection vibration arm, 232…Second detection vibration arm, 240…First support portion, 242…Second support portion, 250…First beam portion, 252…Second beam portion, 254…Third beam portion, 256…Fourth beam portion, 400…Physical quantity detection device, 440…Drive circuit, 441… I / V conversion circuit, 442…AC amplification circuit, 443…Amplitude adjustment circuit, 450…Detection circuit, 451, 452…Charge amplifier, 453…Differential amplification circuit, 454…AC amplification circuit, 455…Synchronous detection circuit, 456…Smoothing circuit, 457…Variable amplification circuit, 458…Filter circuit, 1010…First conductive member, 1020…Second conductive member.

Claims

1. A method for manufacturing a physical quantity detection device, comprising: a physical quantity detection element including a base and a plurality of vibrating arms connected to the base; a detection circuit that detects a detection vibration generated in the physical quantity detection element; a drive circuit that drives the vibrating arms to vibrate; The method for manufacturing a physical quantity detection device has: The vibrating arms include: a first drive vibrating arm having a first weight portion at its tip; a second drive vibrating arm having a second weight portion at its tip; a first detection vibrating arm including a first detection electrode and a second detection electrode; a second detection vibrating arm including a third detection electrode that is disconnected from both the first detection electrode and the second detection electrode, and a fourth detection electrode that is disconnected from both the first detection electrode and the second detection electrode; The method for manufacturing a physical quantity detection device further includes: a first step of preparing the physical quantity detection element; a second step of adjusting at least one of the first drive vibrating arm and the second drive vibrating arm; a third step of electrically connecting the first detection electrode and the third detection electrode, and electrically connecting the second detection electrode and the fourth detection electrode. A method for manufacturing a physical quantity detection device.

2. The method for manufacturing a physical quantity detection device according to Claim 1, wherein the adjustment changes the mass of at least one of the first weight portion and the second weight portion.

3. The method for manufacturing a physical quantity detection device according to Claim 1, comprising a first amplifier to which outputs from the first detection electrode and the third detection electrode are input, and a second amplifier to which outputs from the second detection electrode and the fourth detection electrode are input, and measuring the detection vibration via the first amplifier and the second amplifier before the second step. A method for manufacturing a physical quantity detection device.

4. The method for manufacturing a physical quantity detection device according to Claim 1, wherein the second step is performed after mounting the physical quantity detection element on a package or a support substrate.

5. The method for manufacturing a physical quantity detection device according to Claim 1, wherein the third step electrically connects by adding a conductive member.

6. The method for manufacturing a physical quantity detection device according to Claim 1, wherein the physical quantity detection element is a double-T type gyro sensor element.

7. The method for manufacturing a physical quantity detection device according to Claim 1, wherein the physical quantity detection element is an H type gyro sensor element.

8. A physical quantity detection element including a base portion and a plurality of vibrating arms connected to the base portion, A detection circuit that detects a detection vibration generated in the physical quantity detection element, A drive circuit that drives the vibrating arms to vibrate, A physical quantity detection device having: The vibrating arms include: A first drive vibrating arm having a first weight portion at its tip, A second drive vibrating arm having a second weight portion at its tip, A first detection vibrating arm including a first detection electrode and a second detection electrode, A second detection vibrating arm including a third detection electrode and a fourth detection electrode, And are provided with: The first detection electrode and the third detection electrode are electrically connected by a first conductive member, The second detection electrode and the fourth detection electrode are electrically connected by a second conductive member, A physical quantity detection device in which at least one of the first weight portion and the second weight portion has a processing mark recessed in the thickness direction.

Images