JP2013007622A - Gyro sensor and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gyro sensor that achieves a reduction in size.SOLUTION: A gyro sensor 10 of the present invention includes: a substrate 50; a driving section 24 that is disposed above the substrate 50 through an anchor portion 12 and rotates and vibrates; detecting sections 20 connected to the driving section 24; driving electrode portions 56 disposed on the substrate 50; and driving electrode portions 54 disposed opposite to the detecting sections 20 as viewed in a plan view on the substrate 50. In the gyro sensor 10, the driving section 24 is provided with a plurality of gap portions, and at least parts of the driving electrode portions 56 are provided so as to be overlapped with the gap portions as viewed in the plan view.

Description

  The present invention relates to a gyro sensor and an electronic device using the gyro sensor.

  In recent years, gyro sensors that detect angular velocities are often used for attitude control such as car navigation systems and camera shake correction for video cameras. Such a gyro sensor includes a sensor provided on each axis with a detection element capable of detecting angular velocities around the X, Y, and Z axes orthogonal to each other.

  The sensor structure disclosed in Patent Document 1 includes a drive mass and a drive device, and the drive device is attached radially from the drive mass toward the outside. The drive device includes a comb-like fixed electrode and a movable electrode, and is formed radially from the drive mass at a predetermined interval.

JP 2007-271611 A

However, the configuration in which the driving device is provided on the same plane as the conventional driving mass increases the occupied space of the driving device, and there is a problem that the sensor element cannot be further downsized due to the demand for downsizing of the entire device. It was. Further, if the installation area of the detection unit is reduced in order to secure the space occupied by the driving device, there is a problem that the detection sensitivity is lowered.
In order to solve the above-described problems of the conventional technology, an object of the present invention is to provide a gyro sensor that is miniaturized.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples.
Application Example 1 A Substrate, a Drive Unit which is Disposed Above the Substrate via an Anchor Part, Rotates and Vibrates, a Detection Unit Connected to the Drive Unit, and a Drive Electrode Unit Arranged on the Substrate And a detection electrode unit disposed on the substrate so as to face the detection unit in plan view, and the drive unit includes a plurality of gaps, and at least a part of the drive electrode unit is The gyro sensor is provided so as to overlap the gap in a plan view.

  According to the above configuration, since the space occupied by the drive unit on the sensor can be reduced, the entire sensor can be reduced in size. Further, by increasing the space of the detection unit, it is possible to increase the sensitivity of the detection unit.

Application Example 2 The gyro sensor according to Application Example 1, wherein the drive electrode portion is arranged in a pair with respect to one gap portion.
According to the above configuration, the driving force of the driving unit can be increased.

Application Example 3 The gyro sensor according to Application Example 1 or 2, wherein the driving unit has a substantially circular outer shape.
According to the said structure, a drive part can be circumferentially moved efficiently.

Application Example 4 The gyro sensor according to any one of Application Examples 1 to 3, wherein the anchor portion is disposed at the center of the drive unit.
According to the said structure, a drive part can be circumferentially moved with sufficient balance.

Application Example 5 The gyro sensor according to Application Example 4, wherein the gap portion is disposed at a point-symmetrical position with the anchor portion as a center.
According to the said structure, a drive part can be circumferentially moved efficiently.

Application Example 6 The gyro sensor according to any one of Application Examples 1 to 5, wherein the detection unit is disposed inside the driving unit.
According to the said structure, it contributes to size reduction of a gyro sensor.

  Application Example 7 When two axes intersecting each other in plan view are defined as a first axis and a second axis, the detection unit includes a pair of first detection units arranged in the direction of the first axis; The gyro sensor according to any one of Application Examples 1 to 5, further comprising a pair of second detection units arranged in the direction of the second axis.

  According to the above configuration, angular velocities generated around two axes orthogonal to each other can be detected, and two-axis detection can be realized with one element. In addition, the space occupied by the drive unit on the substrate can be reduced to reduce the size.

Application Example 8 An electronic device comprising the gyro sensor according to any one of Application Examples 1 to 7.
According to the above configuration, an electronic apparatus including a gyro sensor that is reduced in size by reducing the space occupied by the drive unit can be obtained. Further, the entire device can be reduced in size.

It is a top view which shows the structure outline of the gyro sensor of this invention. It is bb sectional drawing of FIG. It is an enlarged view of the aa cross section of FIG. (1) is a plan view of FIG. 3, (2) is a plan view when rotating and oscillating to an arrow a, and (3) is a plan view when rotating and oscillating to an arrow b. It is a perspective view which detects the angular velocity which acts around the X-axis. It is a perspective view which detects the angular velocity which acts around the Y-axis. It is explanatory drawing of the detection part which detects the displacement around a Z-axis. It is explanatory drawing which detects the angular velocity which acts around a Z-axis. It is explanatory drawing of the modification of a space | gap part. It is explanatory drawing of the mobile telephone to which the electronic device provided with the gyro sensor of this invention is applied.

  Embodiments of a gyro sensor and an electronic apparatus of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a plan view showing a schematic configuration of a gyro sensor of the present invention. In FIG. 1, the substrate is omitted. 2 is a cross-sectional view taken along line bb of FIG. In each figure, for convenience of explanation, an X axis, a Y axis, and a Z axis are illustrated as three axes orthogonal to each other. In this embodiment, the direction parallel to the X axis (first axis) is the X axis direction, the direction parallel to the Y axis (second axis) is the Y axis direction, and the direction parallel to the Z axis (third axis) is Z. It is called the axial direction.

  The gyro sensor 10 includes an anchor portion 12, a spring portion 14, a coupling portion 16, a detection portion 20, a drive portion 24 including a drive frame 22, and a substrate 50 disposed below the drive portion 24. ing.

  The drive unit 24 is composed of silicon as a main material, and is formed on a silicon substrate (silicon wafer) with a thin film formation technique (for example, a deposition technique such as an epitaxial growth technique or a chemical vapor deposition technique) or various processing techniques (for example, dry etching). The above-described parts are integrally formed by processing into a desired outer shape using an etching technique such as wet etching. Alternatively, after the silicon substrate and the glass substrate are bonded together, only the silicon substrate is processed into a desired outer shape, whereby the above-described portions can be formed. The drive unit 24 shown in FIG. 1 is formed in a circular shape in plan view, and by using such a shape, it is possible to save space and reduce the size of the entire sensor that vibrates and rotates. By using silicon as the main material of the drive unit 24, excellent vibration characteristics can be realized and excellent durability can be exhibited. Further, it becomes possible to apply a fine processing technique used for manufacturing a silicon semiconductor device, and the gyro sensor 10 can be downsized.

  The anchor part 12 is arranged at the center of rotation of the drive part 24. The anchor part 12 is fixed on the support part 52 of the substrate 50. As a result, the anchor portion 12 is not rotated by the rotation vibration of the drive frame 22.

  The spring portion 14 has flexibility and connects the anchor portion 12 and the coupling portion 16. The spring portion 14 extends along the X axis and the Y axis perpendicular to each other with the anchor portion 12 as a center. The spring portion 14 shown in FIG. 1 extends in a substantially cross direction around the anchor portion 12 and is connected to the connecting portion 16 so as to be extendable and contractable.

  The connecting portion 16 has a predetermined rigidity, and connects the anchor portion 12 and the drive frame 22. The connecting portion 16 shown in FIG. 1 extends in a diagonal direction that bisects the angles of the two axes of the X axis and the Y axis, and connects the anchor portion 12 and the drive frame 22.

  The detection unit 20 includes a movable unit 28 and a shaft unit 30. The movable portion 28 has a substantially fan shape and is connected to the connecting portion 16 via the shaft portion 30. The detection unit 20 having such a configuration includes a first detection unit 20a that detects a displacement around the X axis and a second detection unit 20b that detects a displacement around the Y axis. The 1st detection part 20a is provided with a pair of movable parts 28a and 28b. The movable portions 28a and 28b are attached to the connecting portion 16 so that the shaft portions 30a and 30b are parallel to the Y axis. The shaft portions 30a and 30b are formed at positions shifted from the center of gravity of the movable portions 28a and 28b. When the shaft portions 30a and 30b are displaced, the shaft portions 30a and 30b are torsionally deformed around the shafts to rotate the movable portions 28a and 28b in the Z-axis direction.

  The second detector 20b is provided with a pair of movable parts 28c and 28d. The movable portions 28c and 28d are attached to the connecting portion 16 so that the shaft portions 30c and 30d are parallel to the X axis. The shaft portions 30c and 30d are formed at positions shifted from the center of gravity of the movable portions 28c and 28d. When the shaft portions 30c and 30d are displaced, the shaft portions 30c and 30d are torsionally deformed around the shaft to rotate the movable portions 28c and 28d in the Z axis direction.

  The drive frame 22 is a circular ring, and the anchor part 12, the spring part 14, the connecting part 16, and the detection part 20 are arranged inside. The drive frame 22 and the connecting portion 16 have a predetermined rigidity, and the spring portion 14 can expand and contract around the anchor portion 12 to rotate and vibrate in the arrow A direction. Further, the drive frame 22 is formed with an opening 26 as a gap passing through the front and back of the frame along the circumference. A plurality of openings 26 are formed at positions that are point-symmetric about the anchor.

  The substrate 50 includes a support part 52, a detection electrode part 54, and a drive electrode part 56. As an example of the material of the substrate 50, a glass substrate can be used, and the support portion 52 can be formed by cutting the surface with a predetermined thickness. The support part 52 is bonded to the anchor part 12.

  The detection electrode parts 54a, 54b, 54c, 54d are provided on the substrate 50 facing the movable parts 28a, 28b, 28c, 28d. The detection electrode part 54 and the movable part 28 are formed with a gap corresponding to the length of the support part 52. This gap can be easily adjusted according to the length of the support portion 52. The smaller the gap, the higher the accuracy of detecting the angular velocity. In addition, the gap can be adjusted by changing the thickness of the metal film of the detection electrode portion 54.

Such detection electrode portions 54a, 54b, 54c, and 54d have their capacitances changed by approaching or separating from the movable portions 28a, 28b, 28c, and 28d. By detecting this change in capacitance and obtaining the Coriolis force in the X axis direction or the Coriolis force in the Y axis direction, the angular velocity applied around the X axis or around the Y axis can be detected.
The drive electrode portion 56 is provided on the substrate 50 facing the opening 26.

  FIG. 3 is an enlarged view of the aa cross section of FIG. 4A is a plan view when FIG. 3 is rotated, and FIG. 4B is a plan view when rotating and oscillating in an arrow a, and FIG. 4C is a plan view when rotating and oscillating in an arrow b. .

  As shown in the figure, a pair of drive electrode portions 56a and 56b are provided for one opening. The pair of drive electrode portions 56a and 56b are mounted on the substrate 50 at a predetermined interval and connected to a power source (not shown). An electrostatic force is generated from each of the drive electrode portions 56a and 56b by alternately applying positive and negative voltages to the drive electrode portions 56a or to the drive electrode portions 56b. The gap between the drive electrode portion 56 and the drive frame 22 is small and the electrostatic force is large. On the other hand, the gap between the drive electrode portion 56 and the opening 26 is large and the electrostatic force is small. As a result, the drive frame 22 rotates and vibrates as shown by an arrow A in FIG.

  When the drive frame 22 rotates to the maximum in the direction of the arrow a as shown in FIG. 4B during the rotation vibration, the opening 26 and the drive electrode portion 56 are the plane of the substrate 50 with the Z axis as the normal line. They are arranged so as to overlap each other visually. As shown in FIG. 4C, when the drive frame 22 rotates to the maximum in the direction of the arrow b, the opening 26 and the drive electrode portion 56 overlap each other in plan view of the substrate 50 with the Z axis as a normal line. It is arranged in. Thus, the width of the drive electrode portion 56 is set to be larger than the amplitude of the rotational vibration of the drive frame 22. By arranging the opening and the drive electrode portion 56 so as to overlap each other in plan view during the rotation vibration, the rotation vibration of the drive frame can be smoothly vibrated while maintaining a predetermined frequency. Similarly to the detection electrode portion 54, the drive electrode portion 56 and the drive frame 22 have a gap corresponding to the length of the support portion 52. This gap can be easily adjusted by the length of the support portion 52. The smaller the gap, the larger the electrostatic force and the greater the driving force. In addition, the gap can be adjusted by changing the film thickness of the metal film of the drive electrode portion 56. Although it is conceivable that the drive frame 22 is attracted to the substrate 50 side (Z-axis direction) by electrostatic force during driving, the drive frame 22 is arranged point-symmetrically with the opening 26 as the anchor center as shown in FIG. Since the forces in the Z-axis direction are balanced, the drive frame 22 can be prevented from tilting. As another method, if a plurality of anchor portions 12 are arranged and fixed outside the drive frame 22, the drive frame 22 can be prevented from being inclined.

  In addition to providing a pair of driving electrode portions 56 for one opening 26, one driving electrode portion 56 may be provided for one opening 26. In this case, however, the opening 26 and the drive electrode portion 56 are arranged so as to overlap each other when seen in a plan view during the rotation vibration. The drive unit 24 can employ an electrostatic drive method, a piezoelectric drive method, an electromagnetic drive method using a Lorentz force of a magnetic field, or the like. Further, the detection unit 20 may be configured to be provided outside the drive frame having a reduced outer diameter. A plurality of anchor portions 12 may be arranged on the outside of the drive frame together with the spring portion so as to fix the drive frame so as to freely rotate and vibrate.

The operation of the gyro sensor 10 of the present invention having the above configuration will be described below.
In general, the Coriolis force can be expressed as Equation 1.

  FIG. 5 is a perspective view for detecting the angular velocity acting around the X axis. The drive frame 22 rotates and vibrates in the direction of arrow A. The first detector 20a vibrates in the Y-axis direction, and the second detector 20b vibrates in the X-axis direction. When an angular velocity (Ωx) around the X-axis is applied, the first detector 20a vibrates in the Y-axis direction. The Coriolis force in the Z-axis direction acts on the first detector 20a. When such Coriolis force is applied, in the first detection unit 20a, the movable units 28a and 28b rotate around the shaft units 30a and 30b, and the capacitance between the movable units 28a and 28b and the detection electrode units 54a and 54b. Changes. By detecting this change in capacitance and obtaining the Coriolis force in the Z-axis direction, the angular velocity (Ωx) applied around the X-axis can be detected.

  FIG. 6 is a perspective view for detecting an angular velocity acting around the Y axis. The drive frame 22 rotates and vibrates in the direction of arrow A. When the first detector 20a is vibrated in the Y-axis direction and the second detector 20b is vibrated in the X-axis direction, when an angular velocity (Ωy) about the Y-axis is applied, the first detector 20a vibrates in the X-axis direction. The Coriolis force in the Z-axis direction acts on the second detection unit 20b. When such Coriolis force is applied, in the second detection unit 20b, the movable units 28c and 28d rotate around the shaft units 30c and 30d, and the capacitance between the movable units 28c and 28d and the detection electrode units 54c and 54d. Changes. By detecting this change in capacitance and obtaining the Coriolis force in the Z-axis direction, the angular velocity (Ωy) applied about the Y-axis can be detected.

  According to the gyro sensor 10 as described above, since the occupied space on the sensor can be reduced by the configuration in which the drive electrode portion 56 is provided under the opening 26, the entire sensor can be reduced in size. Sensitivity of the detection unit can be increased by widening the space of the detection unit. Further, the gap between the opening 26 and the drive electrode portion 56 can be reduced, and the drive force can be increased.

FIG. 7 is a plan view showing a schematic configuration of a third detection unit capable of detecting an angular velocity applied around the Z axis.
As shown in FIG. 7, the third detection unit 20 c that can detect the angular velocity applied around the Z axis includes a frame part 70, a spring part 72, and a detection part 77.

  The frame portion 70 is a substantially rectangular frame body in a plan view with the Z axis as a normal line, and is provided on the drive frame 22 in a direction in which the connecting portion 16 extends (hereinafter referred to as a diagonal direction) via a spring portion 72. Yes. By using the space outside the drive frame 22 as described above, the entire sensor can be reduced in size.

  The spring portion 72 includes a first spring portion 74 and a second spring portion 76. The first spring portion 74 has a shape extending in the diagonal direction while reciprocating in a direction orthogonal to the diagonal direction. The configuration of the second spring portion 76 is provided symmetrically with the first spring portion 74 with respect to the diagonal line. The first spring portion 74 and the second spring portion 76 having such a configuration can smoothly expand and contract the frame portion 70 in the radial direction centering on the anchor portion 12 that is the detection direction.

  The detection unit 77 includes a movable electrode 78 and a fixed electrode 79. The movable electrode 78 has both ends connected to the frame portion 70 along the direction of the arrow A that rotates and vibrates. In addition, a plurality of adjacent electrodes may be provided so as to have a predetermined interval. The fixed electrode 79 is provided along the direction of the arrow A that rotates and vibrates in the gap between the movable electrode 78 and the frame portion 70, and the end portion is fixed to a substrate (not shown). The movable electrode 78 and the fixed electrode 79 are formed in a comb shape that is alternately arranged. The detection unit 77 configured as described above generates an electrostatic force between each movable electrode 78 and each fixed electrode 79 by applying a voltage to the electrodes by a power source (not shown). When the frame portion 70 is displaced in the radial direction around the anchor portion 12, the movable electrode 78 approaches or moves away from the fixed electrode 79, and the capacitance changes. A change in the radial direction can be obtained by detecting this change in capacitance.

  FIG. 8 is a perspective view for detecting the angular velocity applied around the Z axis. The drive frame 22 rotates and vibrates in the direction of arrow A. When the angular velocity (Ωz) is applied around the axis in the Z-axis direction while the third detection unit 20c vibrates in the tangential direction of the drive frame 22, the Coriolis force is radiated around the anchor unit 12, in other words, For example, it acts in a direction perpendicular to the tangential direction of the drive frame 22 (arrow F). When the Coriolis force acts in the tangential direction, the capacitance of the detection unit 77 changes as the movable electrode 78 approaches or separates from the fixed electrode 79. By detecting this change in capacitance and obtaining the Coriolis force in the radial direction, the angular velocity (Ωz) applied around the Z axis can be detected. Note that the drive frame 22 always vibrates in the direction of arrow A when the angular velocity is detected. Due to this rotational vibration, the movable electrode of the detection unit 77 may be displaced in the radial direction and detected as a detection value of the third detection unit. Since the rotational vibration is vibrated at a predetermined frequency, it is detected as a constant value. Therefore, the third detection unit 20c may detect the angular velocity (Ωz) applied around the Z axis by signal processing such as taking a difference between the constant detection values.

  Further, by forming the frame portion 70, the movable electrode 78, and the fixed electrode 79 in an arc shape along the outer periphery of the drive frame 22, further space saving can be achieved and the entire sensor can be reduced in size.

  FIG. 9 is an explanatory diagram of a modified example of the gap. The gap portion of the modification includes a thin portion 80 instead of the opening 26 shown in FIGS. In the present invention, the void portion includes both the opening 26 and the thin portion 80. The configuration of the drive electrode portions 56a and 56b is the same. The thin portion 80 is provided on the back surface of the drive frame 22a facing the drive electrode portions 56a and 56b in the same manner as the opening. Further, the thin portion 80 and the drive electrode portions 56a and 56b are arranged so as to be always overlapped in a plan view of the substrate 50 having the Z axis as a normal line during the rotation vibration. The thin portion 80 can be formed by cutting a silicon substrate. When the cutting amount of the thin portion 80 is b and the gap between the drive electrode portions 56a and 56b and the drive frame 22a is a, the thin portion 80 is set so that a <b. According to such a configuration, the electrostatic force increases between the drive electrode portions 56a and 56b and the drive frame 22a, and the electrostatic force decreases between the drive electrode portions 56a and 56b and the thin portion 80. As a result, the drive frame 22a can rotate and vibrate as the spring portion 14 expands and contracts with the anchor portion 12 as a base point. In addition, about the measurement of 1st detection part thru | or 3rd detection part 20a, 20b, 20c, it can detect similarly.

  FIG. 10 is an explanatory diagram of a mobile phone to which an electronic device including the gyro sensor of the present invention is applied. As illustrated, the mobile phone 500 includes a plurality of operation buttons 502, an earpiece 504, and a transmission port 506, and a display unit 508 is disposed between the operation buttons 502 and the earpiece 504. Such a cellular phone 500 has a built-in gyro sensor 10 that functions as an angular velocity detection means.

10 ......... Gyro sensor, 12 ......... Anchor portion, 14 ......... Spring portion, 16 ......... Connecting portion, 20 ......... Detection portion, 20a ......... First detection portion, 20b ......... Second Detection unit, 20c ......... Third detection unit, 22 ......... Driving frame, 24 ......... Driving unit, 26 ......... Opening, 28, 28a, 28b, 28c, 28d ......... Moving unit, 30, 30a , 30b, 30c, 30d ......... Shaft, 50 ......... Substrate, 52 ......... Support, 54, 54a, 54b, 54c, 54d ... Detection electrode, 56, 56a, 56b ......... Drive Electrode part 70 ... Frame part 72 72 Spring part 74 First spring part 76 Second spring part 77 Detection part 78 Movable electrode 79 ......... Fixed electrode, 80 ......... Thin part, 500 ......... Cellular phone, 502 ......... Operation buttons, 504 ...... earpiece, 506 ......... transmission ports, 508 ......... display unit.

Claims (8)

A substrate,
A drive unit that is disposed above the substrate via an anchor unit and vibrates in rotation;
A detection unit connected to the drive unit;
A drive electrode portion disposed on the substrate;
A detection electrode unit disposed on the substrate so as to face the detection unit in plan view,
The drive unit is provided with a plurality of gaps,
At least a part of the drive electrode portion is provided so as to overlap the gap portion in plan view.   2. The gyro sensor according to claim 1, wherein a pair of the drive electrode portions are arranged with respect to one of the gap portions.   The gyro sensor according to claim 1, wherein the driving unit has a substantially circular outer shape.   The gyro sensor according to any one of claims 1 to 3, wherein the anchor portion is disposed at a center of the driving portion.   The gyro sensor according to claim 4, wherein the gap is disposed at a point-symmetrical position with respect to the anchor portion.   The gyro sensor according to claim 1, wherein the detection unit is disposed inside the drive unit. When two axes intersecting each other in plan view are defined as a first axis and a second axis,
The said detection part has a pair of 1st detection part arrange | positioned in the direction of the said 1st axis | shaft, and a pair of 2nd detection part arrange | positioned in the direction of the said 2nd axis | shaft. Item 6. The gyro sensor according to any one of Items 1 to 5.   An electronic apparatus comprising the gyro sensor according to claim 1.