JP2003083749A - Physical quantity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a physical quantity sensor capable of being made efficient and more inexpensive because of a simple structure. SOLUTION: Carrier signal voltages PW1-PW4 applied across movable electrodes 1a-1d and fixed electrodes 2a-2d are temporally changed over, to a case detecting a change in electrostatic capacity in a detection direction and a case detecting a change in electrostatic capacity in a vibration direction. The voltage of a vibrator 1 is outputted to a C-V converter circuit 4 connected from the vibrator 1 by one signal line, and potentials in respective states are stored in first - fourth sample hold circuits 5a-5d. Then, the differentials of the first and second sample hold circuits 5a and 5b or the differentials of the third and fourth sample hold circuits 5c and 5d are calculated by first and second differential amplifying circuits 6 and 7. By this constitution, an angular velocity sensor capable of performing vibration monitoring and the detection of Coriolis force can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a physical quantity sensor having a vibrator supported on a plane substrate surface so as to be displaceable in two-axis orthogonal coordinate directions, and is suitable for use in, for example, an angular velocity sensor. .

[0002]

2. Description of the Related Art Generally, an angular velocity sensor uses a direction perpendicular to a vibration direction of a vibrator as an angular velocity axis, and detects a Coriolis force acting in an axial direction perpendicular to both the vibration direction and the angular velocity axis to detect the angular velocity. Is detected.

In recent years, miniaturization and cost reduction of an on-vehicle angular velocity sensor have been desired, and a method of forming a vibrator and a detection element on a semiconductor (mainly Si) substrate has been studied.
In such a semiconductor type angular velocity sensor, the vibration axis and the detection axis are arranged on the surface of the Si substrate, and the displacement is measured by the capacitance between the fixed electrode fixed to the substrate and the movable electrode provided on the vibrator. Is detected as a change.

In such an angular velocity sensor, when the vibrator vibrates obliquely, a large displacement occurs on the detection axis, which becomes an error signal. As a structure to prevent this with a vibrator, 2
Different types of structures are considered. One is a structure in which a vibrator that is displaceable only in the vibration direction is supported on a vibrator that is displaceable only in the detection direction, and the other is a frame that supports a portion that vibrates only in the vibration direction. The structure is such that it is supported so as to be displaced only in the direction of detection, and the displacement is detected by the outer fixed electrode.

[0005]

However, the above-mentioned 1
In the second structure, it is necessary to etch between the vibrating portion and the detecting portion, which complicates the processing process and makes it difficult to reduce the manufacturing cost.

Further, in the second structure, although the machining process is simplified, there is a problem in that the vibrator and the detection portion are the same electrode and it is difficult to detect the displacement at the same time. As a means to detect this displacement at the same time, a method has been proposed in which vibration is applied for several cycles of driving vibration and the electrodes are switched to the detection circuit during free vibration.However, with such a configuration, the amplitude is attenuated during free vibration. However, since the sensitivity changes, the correction means is required, which hinders cost reduction.

In view of the above points, the present invention is to provide a physical quantity sensor which has a simple structure and can be efficiently and cost-effectively.

[0008]

In order to achieve the above object, in the invention described in claim 1, the movable electrodes (1a-1)
d) having a movable part (1) supported on the surface of the plane substrate so as to be displaceable in the directions of two-axis orthogonal coordinates, and fixed electrodes (2a to 2d) facing the movable electrode of the movable part. And a fixed electrode provided on the fixed portion, electrostatic capacitance is formed in a biaxial orthogonal direction by the movable electrode provided on the movable portion and a fixed electrode provided on the fixed portion. In a physical quantity sensor that detects vibration in any of the directions based on a change in capacitance in the directions orthogonal to the two axes, a carrier signal voltage (PW1 to PW) applied between a movable electrode and a fixed electrode.
4) is temporally switched for each of the directions orthogonal to the two axes,
It is characterized in that the displacement in the biaxial directions is detected by one signal line from the vibrator.

In the physical quantity sensor having such a configuration, the processing steps are not complicated, and since the vibrator and the detection section do not have the same electrode, the displacement can be detected at the same time. Accordingly, it is possible to provide a physical quantity sensor that can efficiently achieve a cost reduction with a simple structure.

According to a second aspect of the invention, the movable electrode (1
a) to 1d), and a vibrator (1) supported on the plane substrate surface so as to be displaceable in biaxial orthogonal coordinate directions, and fixed electrodes (2a to 2d) facing the movable electrode of the vibrator. A vibrating vibrator in one of the biaxial orthogonal coordinate directions, the vibrating direction is the vibrating direction, and the direction perpendicular to the vibrating direction on the plane substrate surface is the detecting direction. Then, the movable electrode and the fixed electrode form an electrostatic capacitance in the vibration direction and the detection direction with respect to the vibrator, and in the angular velocity sensor for detecting the angular velocity by detecting the electrostatic capacitance change, the movable electrode and the fixed electrode are The carrier signal voltages (PW1 to PW4) applied in between are temporally switched between the case of detecting a change in capacitance in the detection direction and the case of detecting a change in capacitance in the vibration direction, and the one from the vibrator is set. In the signal line, it is characterized by being adapted to detect the two axial directions of displacement. As described above, the configuration described in claim 1 can be applied to the angular velocity sensor.

According to the third aspect of the present invention, the vibrator is excited by generating an electrostatic force between the movable electrode and the fixed electrode, and the electrostatic force in the vibration direction and the detection direction with respect to the vibrator is generated. The feature is that excitation is added to the detection of the capacitance change, and the detection and the excitation of the capacitance change are time-divided and periodically performed. In this way, it is possible to alternately perform capacitance detection and excitation.

The invention according to claim 4 is characterized in that the rate of time division is set to be larger in detection of capacitance change in the vibration direction than in detection or excitation of capacitance change in the detection direction. . By doing so, it is possible to reduce the noise of the vibration monitoring signal which is the reference signal of the synchronous detection and bring it closer to the sine wave, and reduce the error in the synchronous detection.

The invention according to claim 5 is characterized in that the ratio between the excitation signal for exciting the vibrator and the frequency of the carrier signal is an integral multiple. In this way, since the stepwise distortion of the detection signal is synchronized with the excitation frequency, it is easy to remove it by synchronous detection.

The reference numerals in parentheses of the above means indicate the correspondence with the specific means described in the embodiments described later.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a schematic configuration of an angular velocity sensor to which an embodiment of the present invention is applied. The configuration of the angular velocity sensor will be described below with reference to FIG.

The angular velocity sensor includes an element section 3 having a vibrator 1 and a fixed section 2, a CV conversion circuit section 4, a sample hold circuit section 5, first and second differential amplification circuit sections 6, 7,
The synchronous detection circuit unit 8, the sensitivity adjustment circuit unit 9, the excitation signal generation circuit unit 10, and the switching control circuit 11 are provided. Then, the excitation signal generating circuit unit 10 vibrates the vibrator and controls each component based on various drive signals generated by the switching control circuit 11, thereby detecting the angular velocity.

The element portion 3 is provided with a vibrator 1 and a fixed portion 2, the vibrator 1 is provided with movable electrodes 1a to 1d, and the fixed portion 2 is provided with respect to the movable electrodes 1a to 1d. Fixed electrodes 2a to 2d are provided at desired intervals. The vibrator 1 and the fixed portion 2 which constitute the element portion 3
Is formed of a semiconductor substrate, and the vibrator 1 is supported so as to be displaceable in a biaxial orthogonal coordinate direction with respect to the fixed portion 2. The capacitance is set between the movable electrodes 1a to 1d and the fixed electrodes 2a to 2d provided on the vibrator 1 and the fixed portion 2. Specifically, when the vibration direction is the left-right direction on the paper surface with respect to the vibrator 1, the direction perpendicular to the vibration direction on the paper surface corresponds to the detection direction, and the capacitance changes in the vibration direction and the detection direction. Thus, the movable electrodes 1a to 1d and the fixed electrodes 2a to 2d are provided. Element part 3 configured in this way
Among them, the voltage signal PW1 from the switching control circuit 11 is applied to each of the fixed electrodes 2a to 2d provided in the fixed portion 2.
~ PW4 is added. The voltage signals PW1 to PW4 are set to either 0 [V] or Va [V]. Hereinafter, these voltage signals PW1 to PW4 are referred to as carrier signals.

The CV conversion circuit section 4 is connected to the vibrator 1 by a single signal line, and based on the voltage of the vibrator 1, the differential capacitance of the movable electrodes 1a to 1d and the fixed electrodes 2a to 2d. Is converted into a voltage. The basic configuration and basic operation of the C-V conversion circuit unit 4 will be described with reference to the operation state diagram shown in FIG.

As shown in FIGS. 2A and 2B, C-V
The conversion circuit unit 4 has a configuration including an operational amplifier 4a, a capacitor 4b, and a switch 4c. Operational amplifier 4
The inverting input terminal of a is connected to the vibrator 1, and the capacitor 4b and the switch 4c are connected in parallel between the inverting input terminal and the output terminal. The switch 4c is adapted to be driven by a signal S1 from the switch control circuit unit 11, and a voltage Va [V applied to the fixed electrodes 2a to 2d by a constant voltage source or the like is applied to the non-inverting input terminal of the operational amplifier 4a. ] Half the voltage Va / 2 [V] is input.

The operation of the CV conversion circuit section 4, that is, the conversion of the capacitance change into the voltage signal is performed as follows. Fixed electrodes 2a to 2d provided in the above-mentioned fixed portion 2
In the initial state, the movable electrodes 1a to 1d provided on the vibrator 1 have equal capacitances formed on both sides in the vibration direction with respect to the vibrator 1, and are formed on both sides in the detection direction with respect to the vibrator 1. The formed capacitors are set to have equal capacities. The CV conversion by the capacitance formed on both sides of the vibrator 1 in the vibration direction and the CV conversion by the capacitance formed on both sides of the vibrator 1 in the detection direction are similarly
The switching capacitor method is performed as follows.

First, as shown in FIG. 2A, a voltage Va is applied to one of the fixed electrodes 2a and 2c on the basis of various signals from the switching control circuit unit 11 and the other fixed electrode 2b is applied. The voltage 0 is applied to 2d and the switch 4c is closed. As a result, the vibrator 1 (movable electrodes 1a to 1d) and each fixed electrode 2a
Let Ca and Cb be the capacitances between 2d and 2d, respectively.
Ca x Va / 2 and -Cb x Va for a and Cb, respectively.
/ 2 charge is stored, and the output of the operational amplifier 4a is Va
/ 2. Hereinafter, this state is referred to as state 1.

Then, based on various signals from the switching control circuit section 11, the voltage applied to each of the fixed electrodes 2a to 2d is inverted from that in the state 1, and the switch 4c is opened. As a result, the charges of Ca and Cb become −Ca × Va / 2 and Cb × Va / 2, respectively. Therefore, the change in charge is (Ca−Cb) × Va. At this time, since the switch 4c is opened, this change in charge is connected to the output of the operational amplifier 4a via the capacitor 4b, and the operational amplifier 4a outputs (Ca−Cb) ×
A potential of Va / Cf + Va / 2 is output. Hereinafter, this state is referred to as state 2.

Therefore, by taking the difference between the output of the operational amplifier 4a in the state 1 and the output of the operational amplifier 4a in the state 2, a voltage output proportional to the capacitance difference of (Ca-Cb) * Va / Cf can be obtained. it can. Then, by repeating these operations alternately in both the vibration direction and the detection direction, the displacement of the vibrator 1 in the vibration direction is monitored, and the Coriolis force is detected by the displacement of the vibrator 1 in the detection direction. There is.

The sample and hold circuit section 5 includes the first to fourth sections.
The sample-hold circuits 5a to 5d are composed of four sample-hold circuits. Each of the sample hold circuits 4a to 4d is driven based on the control signals S2 to S5 of the switching control circuit unit 11 and stores the output voltage of the operational amplifier 4a at a predetermined timing. Specifically, the first sample-hold circuit 5a stores the output voltage of the operational amplifier 4a when the state 1 is set in the vibration direction, and the second sample-hold circuit 5b is set the state 2 in the vibration direction. The operational amplifier 4 stores the output voltage of the operational amplifier 4a, and the third sample hold circuit 5c sets the state 1 in the detection direction.
The output voltage of a is stored in the fourth sample hold circuit 5
d stores the output voltage of the operational amplifier 4a when the state 2 is set in the detection direction.

The first differential amplifier circuit section 6 includes a first sample hold circuit 5a and a second sample hold circuit 5b.
The potential difference is amplified by a predetermined amplification factor. The second differential amplifier circuit section 7 amplifies the potential difference between the third sample hold circuit 5c and the fourth sample hold circuit 5d at a predetermined amplification factor.

The synchronous detection circuit 8 synchronizes the output of the first differential amplifier circuit section 6 with the output of the second differential amplifier circuit section 7. It is possible to synchronize the monitoring timing of the displacement of the vibrator 1 and the Coriolis force detection timing of the displacement of the vibrator 1 in the detection direction.

The sensitivity adjusting circuit 9 is composed of, for example, a DC amplifier composed of an inverting amplifier circuit and the like, and outputs an output signal indicating the displacement of the vibrator 1 in the vibration direction and the displacement of the vibrator 1 in the detection direction as sensitivity. It is adjusted accordingly.

The excitation signal generation circuit 10 applies a force (excitation signal) for vibrating the vibrator 1 in the vibration direction, and obtains the amplitude information of the vibrator 1 from the output of the first differential amplifier circuit 6. Then, feedback control is performed to adjust the force applied to the vibrator 1 based on this amplitude information.

Next, a method of detecting the angular velocity by the angular velocity sensor thus constructed will be described. FIG. 3 shows signals PW1 to PW generated by the switching control circuit 11.
A time chart of the excitation signal generated by W4, S1 to S6, and the excitation signal generation circuit 10 is shown, and will be described with reference to this figure.

First, based on the excitation signal from the excitation signal generation circuit 10, the vibrator 1 is excited in the vibration direction at a predetermined cycle. At this time, the vibration of the vibrator 1 in the vibration direction is set to the resonance frequency, and a larger vibration amplitude is generated. As a result, when angular velocity occurs,
Large Coriolis force can be obtained. In this state, the displacement of the vibrator 1 in the vibration direction is monitored, and the Coriolis force is detected by the displacement of the vibrator 1 in the detection direction.

Next, the displacement of the vibrator 1 in the vibration direction is monitored. In this case, the voltage Va is applied to the fixed electrode 2a and the voltage 0 is applied to the fixed electrode 2b by the voltage signals PW1 and PW2 from the switching control circuit unit 11 (see period t1). This allows
State 1 is obtained in the vibration direction. Then, by the signal S2 from the switching control circuit unit 11, the output potential of the operational amplifier 4a in the CV conversion circuit unit 4 at this time is stored in the first sample hold circuit 5a.

Then, the voltage signals PW1 and PW2 from the switching control circuit section 11 are used to switch the voltage between the fixed electrode 2a and the fixed electrode 2b so that the fixed electrode 2a has a voltage of 0,
The voltage Va is applied to the fixed electrode 2b (see period t2).
As a result, the state 2 is set in the vibration direction. Then, by the signal S3 from the switching control circuit unit 11, the output potential of the operational amplifier 4a in the CV conversion circuit unit 4 at this time is stored in the second sample hold circuit 5b.

Next, the Coriolis force is detected by the displacement of the vibrator 1 in the detection direction. In this case, by the carrier signals PW3 and PW4 from the switching control circuit unit 11, the voltage Va is applied to the fixed electrode 2c and the voltage 0 is applied to the fixed electrode 2d (see period t3). As a result, the state 1 is set in the detection direction. Then, by the signal S4 from the switching control circuit unit 11, the output potential of the operational amplifier 4a in the CV conversion circuit unit 4 at this time is stored in the third sample hold circuit 5c.

Subsequently, the carrier control signals PW3 and PW4 from the switching control circuit section 11 switch the voltage between the fixed electrode 2c and the fixed electrode 2d, and apply the voltage 0 to the fixed electrode 2c and the voltage Va to the fixed electrode 2d ( See period t4). As a result, the state 2 is set in the detection direction. Then, the signal S from the switching control circuit unit 11
5, the output potential of the operational amplifier 4a in the C-V conversion circuit unit 4 at this time is changed to the fourth sample hold circuit 5
Store in d.

In this way, when the outputs of the operational amplifier 4a in the states 1 and 2 in the vibration direction and the detection direction are stored in the respective sample hold circuits 5a to 5d, the first and second differential amplifier circuits 6 and 7 will be described. As a result, the potential difference between the first sample-hold circuit 5a and the second sample-hold circuit 5b is amplified by a predetermined amplification factor, and the potential difference between the third sample-hold circuit 5c and the fourth sample-hold circuit 5d is predetermined. It is amplified at the amplification rate. After that, after the outputs of the differential amplifier circuit units 6 and 7 are synchronized in the synchronous detection circuit unit 8, the sensitivity is appropriately adjusted by the sensitivity adjusting circuit 9 and output as an output signal of the angular velocity sensor. FIG. 4 shows the results of monitoring the vibration of the vibrator and the results of detecting the Coriolis force together with the outputs X1 and X2 of the differential amplifier circuits 6 and 7 at this time.

In such angular velocity detection, when a rectangular wave having a frequency of about 100 kHz is used as the carrier signals PW1 to PW4, it is possible to alternately obtain vibration monitoring and detection signals at intervals of about 20 μsec. . Generally, the excitation frequency is below a few kHz, so
The sampling period for vibration monitoring and Coriolis force detection is faster, and the signals can be measured without being attenuated.

The angular velocity sensor capable of detecting the angular velocity can be configured as described above. In the angular velocity sensor having such a configuration, the machining process is not complicated, and since the vibrator and the detection unit do not have the same electrode, the displacement can be detected at the same time. This makes it possible to provide an angular velocity sensor that has a simple structure and that can be manufactured efficiently and at low cost.

(Second Embodiment) FIG. 5 shows a schematic structure of an angular velocity sensor according to a second embodiment of the present invention. As shown in FIG. 5, in the present embodiment, by adding the fixed electrodes 12a and 12b to the first embodiment, capacitance for excitation is added, and at the same time, the vibrator 1 and the CV conversion circuit are added. A switch SW1 is provided between the excitation signal generating circuit unit 10 and the vibrator 1, and a switch SW2 whose ON / OFF is opposite to that of the switch SW4 is provided between the excitation signal generating circuit unit 10 and the vibrator 1.

In such a configuration, vibration monitoring and Coriolis force detection are performed in the same manner as in the first embodiment, and the vibrator 1 is vibrated based on the excitation signal (output voltage) from the excitation signal generation circuit section 10. To Specifically, the switch SW1 is turned on and the switch SW2 is turned off during capacitance detection for vibration monitoring and Coriolis force detection.
And the voltage signal D from the switch control circuit unit 10
Based on R1 and DR2, the potentials of the fixed electrodes 12a and 12b are made equal to those of the movable electrodes 1a and 1b, and when the vibrator 1 is excited, the switch SW1 is turned off and the switch SW2 is turned off so that the potentials of the fixed electrodes 12a and 12b are changed. Movable electrode 1
A potential difference is generated between a and 1b, which creates the necessary electrostatic force,
Capacitance detection and vibration of the vibrator 1 are alternately performed. This prevents the excitation signal from wrapping around.

FIG. 6 shows the differential amplifier circuit sections 6 and 7 when the angular velocity is detected by the angular velocity sensor of this embodiment.
X1 and X2 of the output, the vibration monitoring result of the vibrator, the Coriolis force detection result, and the fixed electrodes 12a, 1
2b shows voltage signals DR1, DR2 to 2b.

As shown in this embodiment, it is possible to alternately perform capacitance detection and excitation. Even in this case, the same effect as in the first embodiment can be obtained.

(Third Embodiment) In the second embodiment,
In vibration monitoring, the ratios of Coriolis force detection and excitation are made equal, but in the present embodiment, these ratios are changed using the same configuration of the angular velocity sensor as in the second embodiment. That is, the ratio of vibration monitoring is made higher than the ratio of Coriolis force detection or excitation, and vibration monitoring is performed every time Coriolis force detection or excitation is performed.

FIG. 7 shows the outputs X1 and X2 of the differential amplifier circuit units 6 and 7 in the case of the present embodiment, the monitoring result of the vibration of the vibrator, the detection result of the Coriolis force, and the fixed electrode 12a. , 12b voltage signals DR1, DR2
Indicates.

In the angular velocity sensor of this structure, since the signal is taken out in time division, the sine wave signal originally generated from the sensor element is distorted stepwise. In the angular velocity sensors shown in the first and second embodiments, the synchronous detection circuit unit 8 is used to remove signals other than the excitation signal frequency. However, if the reference signal is distorted, its performance is reduced. Is reduced.

Therefore, as in the present embodiment, the detection rate of the vibration monitoring signal serving as the reference signal is made larger than the rate of Coriolis force detection or excitation, so that the vibration monitoring signal, which is the reference signal of the synchronous detection circuit unit 8, is detected. It is possible to reduce the noise of (1) and bring it closer to a sine wave, and reduce the error in the synchronous detection circuit unit 8.

(Fourth Embodiment) FIG. 8 shows a schematic structure of an angular velocity sensor according to a fourth embodiment of the present invention. This embodiment is different from the first embodiment in that a PL as a multiplication circuit is used.
It is equipped with L13. By providing the PLL 13 as such a multiplication circuit, the cycle of the excitation signal can be an integral multiple of the cycle in which capacitance detection including excitation is performed once.

FIG. 9 shows the outputs X1 and X2 of the differential amplifier circuits 6 and 7 in the case of the present embodiment, the vibration monitoring result of the vibrator, the Coriolis force detection result, and the fixed electrode 12a. , 12b voltage signals DR1, DR2
Indicates.

The carrier signal P set in this way
By using W1 to PW4 and the voltage signals DR1 and DR2, the stepwise distortion described in the third embodiment is synchronized with the excitation frequency, so that the synchronous detection circuit unit 8 can easily remove it.

(Fifth Embodiment) FIG. 10 shows the fifth embodiment of the present invention.
1 shows a schematic configuration of an acceleration sensor in an embodiment. In this embodiment, one embodiment of the present invention is applied to an acceleration sensor that can independently detect acceleration in two-axis orthogonal coordinate directions. As shown in this figure, the present invention may be applied to an acceleration sensor. In this case, in FIG.
The excitation signal generation circuit section 10 shown in FIG.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an angular velocity sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a detection principle of an angular velocity sensor.

FIG. 3 is a diagram showing a timing chart of each signal when the angular velocity sensor shown in FIG. 1 is in operation.

FIG. 4 is a diagram showing a vibration monitoring result and a Coriolis force detection result in the first embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of an angular velocity sensor according to a second embodiment of the present invention.

FIG. 6 is a diagram showing vibration monitoring results and Coriolis force detection results according to the second embodiment of the present invention.

FIG. 7 is a diagram showing vibration monitoring results and Coriolis force detection results according to the third embodiment of the present invention.

FIG. 8 is a diagram showing a schematic configuration of an angular velocity sensor according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a vibration monitoring result and a Coriolis force detection result in the fourth embodiment of the present invention.

FIG. 10 is a diagram showing a schematic configuration of an acceleration sensor according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Oscillator, 1a-1d ... Movable electrode, 2 ... Fixed part, 2a
2d ... Fixed electrode, 3 ... Element part, 4 ... CV conversion circuit part, 5 ... Sample hold circuit part, 6, 7 ... 1st, 2nd
Differential amplification circuit section, 8 ... Synchronous detection circuit section, 9 ... Sensitivity adjusting circuit section, 10 ... Excitation signal generating circuit section, 11 ... Switching control circuit section, 12a, 12b ... Fixed electrode.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junji Hayakawa             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Nonoyama Hayashi             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F term (reference) 2F105 AA02 BB12 BB15 CC04 CD03                       CD05 CD11 CD13                 4M112 AA02 BA07 CA24 CA26 CA31                       FA01 FA20

Claims (5)

[Claims] 1. A movable part (1) having movable electrodes (1a-1d), which is supported on a plane substrate surface so as to be displaceable in directions orthogonal to two axes, and a movable electrode facing the movable part. Fixed electrodes (2a-2)
d) having a fixed portion (2), wherein a movable electrode provided in the movable portion and a fixed electrode provided in the fixed portion form a capacitance in the direction orthogonal to the two axes. A physical quantity sensor in which the movable portion detects vibration in any direction of the biaxial orthogonal coordinate direction based on a change in capacitance in the biaxial orthogonal direction, wherein the movable portion is applied between the movable electrode and the fixed electrode. The carrier signal voltages (PW1 to PW4) to be switched are temporally switched for each direction of the biaxial orthogonal direction, and the displacement of the biaxial directions is detected by one signal line from the vibrator. A physical quantity sensor characterized in that 2. A vibrator (1) having movable electrodes (1a-1d) and supported on a plane substrate surface so as to be displaceable in biaxial orthogonal coordinate directions; and a movable electrode of the vibrator (1). Fixed electrodes (2a-2)
d) having a fixed portion (2), the vibrator is vibrated in one of the biaxial orthogonal coordinate directions, and the vibrating direction is a vibrating direction, which is the vibrating direction on the plane substrate surface. When the vertical direction is the detection direction, electrostatic capacitance is formed by the movable electrode and the fixed electrode in the vibration direction and the detection direction with respect to the vibrator, and the angular velocity is detected by detecting the capacitance change. In the angular velocity sensor to be performed, the carrier signal voltage (PW1 to PW4) applied between the movable electrode and the fixed electrode is used to detect a capacitance change in the detection direction and a capacitance change in the vibration direction. An angular velocity sensor characterized in that the displacement is bidirectionally detected by a single signal line from the vibrator when the detection is performed. 3. The vibrator is excited by generating an electrostatic force between the movable electrode and the fixed electrode, and a capacitance change in a vibration direction and a detection direction with respect to the vibrator. 3. The angular velocity sensor according to claim 2, wherein the excitation is added to the detection of, and the detection of the capacitance change and the excitation are periodically performed by time division. 4. The time division ratio is set such that the detection of the capacitance change in the vibration direction is larger than the detection of the capacitance change in the detection direction and the excitation. The angular velocity sensor according to item 3. 5. The angular velocity sensor according to claim 3, wherein the ratio of the excitation signal for exciting the vibrator and the frequency of the carrier signal is an integral multiple.