Sensor element, method for manufacturing sensor element, sensor device, and electronic apparatus

A sensor element includes a base part, drive vibration arms that extend from the base part, an adjustment vibration arm 241 that extends from the base part and vibrates in response to drive vibration of the drive vibration arms, detection electrodes that output a signal according to a physical quantity applied to the drive vibration arms, and adjustment electrodes 551 and 553 provided on the adjustment vibration arm 241 and electrically connected to the detection electrodes for outputting a charge in a reverse polarity with respect to the detection electrodes in response to vibration of the adjustment vibration arm 241. The adjustment electrode 551 has a common part 60 electrically connected to the detection electrodes and a plurality of branch parts 61 branching out from the common part 60 and arranged side by side along an extension direction of the adjustment vibration arm 241.

BACKGROUND

1. Technical Field

The present invention relates to sensor elements, methods for manufacturing a sensor element, sensor devices and electronic apparatuses.

2. Related Art

Angular velocity sensors (vibration gyro sensors) have been known (see, for example, JP-A-2008-14887 (Patent Document 1)) as sensor elements that are used for body control in vehicles, self-position detection of car navigation systems, vibration control and compensation systems (such as, shake compensation) for digital cameras, digital video cameras, and the like, and detect physical quantity, such as, angular velocity, acceleration and the like. For example, an angular velocity sensor described in Patent Document 1 has a tuning-fork element formed from two arms and a connection section that connects one ends of these two arms. Also, in the angular velocity sensor described in Patent Document 1, the tuning-fork element is formed from non-piezoelectric material, and each of the arms is provided with a driving section made of a pair of electrodes and a piezoelectric thin film sandwiched there the electrodes and a detecting section.

In the angular velocity sensor described in Patent Document 1, a voltage is applied between the pair of electrodes of the driving section, thereby flexurally vibrating (driving) the arms. In this driving state, when the arms receive an angular velocity about their axis extending along the arm's longitudinal direction, the arms bend in a direction orthogonal to the driving direction due to Coriolis force, and a charge according to the amount of the bend is detected by the pair of electrodes. The angular velocity can be detected based on the detected charge.

The tuning-fork element having the two arms described above may generally be formed by etching a substrate. However, it is difficult to obtain dimensions of the tuning-fork element precisely according to the design due to etching anisotropy of the substrate, variations in working process, and the like. As a result, the tuning-fork may be formed into a shape that is not originally intended, such that the arms may bend in a direction that is different from the driving direction, even when an angular velocity is not applied to the arms. If a charge that is generated by the pair of electrodes at the detecting section, which may be caused by such bending of the arms, is detected, the detection accuracy would be deteriorated.

Therefore, according to the angular velocity sensor described in Patent Document 1, a portion of one of the pair of electrodes at the detecting section 1 is removed, thereby adjusting the amount of charge to be outputted from the pair of electrodes at the detection section in the state where no angular velocity is applied to the arms. However, according to the angular velocity sensor described in Patent Document 1, it is difficult to make highly accurate adjustment of the amount of charge to be outputted from the pair of electrodes at the detection section.

SUMMARY

In accordance with some aspects of the invention, sensor elements that can readily and reliably exhibit excellent detection sensitivity, methods for manufacturing such sensor elements, sensor devices using such sensor elements can be provided. Also, highly reliable electronic apparatuses equipped with such a sensor device can be provided.

An advantage of some aspects of the invention is to solve at least a part of the problem described above, and the invention can be implemented as the following embodiments and application examples.

Application Example 1

A sensor element in accordance with an embodiment of the invention includes: a base part; a drive vibration arm for drive vibration that extends from the base part; a vibration arm that extends from the base part and vibrates in response to drive vibration of the drive vibration arm; and a detection part including a detection electrode that outputs a signal according to a physical quantity applied to the drive vibration arm, the vibration arm having an electrode that is electrically connected to the detection electrode and generates a charge in a reverse polarity with respect to a charge to be generated from the detection electrode when no physical quantity is applied to the drive vibration arm, and the electrode including a common part provided along an extension direction of the vibration arm and plural branch parts branching out from the common part. The sensor element thus configured has the electrode provided on the vibration arm generate a charge in reverse polarity against a leakage output of the detection electrode that may be generated due to cross-sectional asymmetry of the drive vibration arm, thereby cancelling out the leakage output, which can be outputted as a sensor output.

By cutting at least one branch part midway among the plural branch parts of the electrode or the common part midway, the charge to be generated from the electrode can be reduced, and thus the sensor output can be adjusted. More specifically, the sensor output can be adjusted (corrected) such that the sensor output in the state in which no physical quantity is applied to the sensor element becomes a desired reference value (for example, zero).

In particular, the plural of branch parts branch out from the common part, such that, even when any arbitrary one of the branch parts is cut off, the remaining portion of the branch parts can maintain their electrically connected state with the detection electrode. In other words, the electrode area of the electrode can be reduced by the amount of the arbitrary one cut among the plural branch parts. Further, the plural branch parts are arranged side by side along the extension direction of the vibration arm, such that the sensor output can be readily and highly accurately adjusted according to the position and the number of the branch parts to be cut. Accordingly, the sensor element in accordance with the embodiment of the invention can readily and securely exhibit excellent detection sensitivity.

Application Example 2

In the sensor element in accordance with an aspect of the invention, it is preferred that each of the plural branch parts may have an electrode width greater on the side of a tip portion thereof than on the side of the common part. Accordingly, the electrode can secure a large electrode area before adjustment (before the common part or the branch parts are cut midway), a wide adjustment range can be secured for adjusting the sensor output through cutting off the common part or the branch parts midway, and mid portions of the branch parts can be cut with relative ease.

Application Example 3

In the sensor element in accordance with an aspect of the invention, it is preferred that the plural branch parts may have mutually different electrode areas. Therefore, adjustment of the amount of charge generated from the electrode can be readily performed. More specifically, the amount of charge according to each of the electrode areas may be calculated in advance, and a portion of the branch parts corresponding to a charge amount equivalent to the amount of charge of leakage output of the detection electrode may be cut, whereby the adjustment can be accurately conducted.

Application Example 4

In the sensor element in accordance with an aspect of the invention, it is preferred that the plural branch parts may be inclined with respect to the extension direction of the vibration arm. Accordingly, mid portions of the branch parts can be readily cut. More specifically, when cutting the branch parts by a laser beam, the branch parts can be cut by moving the laser beam in either the X-axis direction or the Y-axis direction. Accordingly, it is not necessary to consider the orientation of the sensor element to be disposed with respect to the laser beam, such that the manufacturing efficiency can be improved.

Application Example 5

In the sensor element in accordance with an aspect of the invention, it is preferred that the plural branch parts may branch out on both sides of the common part. By this structure, the common part can be prevented or suppressed from functioning as the adjustment electrode. Accordingly, adjustment of the sensor output can be readily performed. Also, the adjustment electrode before adjustment (before the common part or the branch parts are cut midway) can secure a large electrode area.

Application Example 6

In the sensor element in accordance with an aspect of the invention, the vibration arm may preferably have a first surface, a second surface on the opposite side of the first surface, and a side surface connecting the first surface and the second surface, and the electrode may preferably have the common part and the plural branch parts provided on at least one of the first surface and the second surface, and a side surface electrode provided on the side surface. A second electrode may be disposed opposite to tip portions of at least a plurality of the branch parts of a first electrode such that the charge to be generated between the branch parts and the second electrode can be used for charge adjustment.

Application Example 7

In the sensor element in accordance with an aspect of the invention, the vibration arm may have a groove portion provided along the extension direction thereof, and at least a portion of the plural branch parts may preferably be provided on a wall surface of the groove part. Accordingly, the distance between the branch parts of the electrode and adjacent electrodes becomes shorter, such that the charge to be outputted from the electrode can be made greater. Therefore, the range of adjustment of the sensor output can be made wider.

Application Example 8

In the sensor element in accordance with an aspect of the invention, the common part and the plural branch parts may be provided on each of the first surface and the second surface, and the plural branch parts provided on the first surface and the plural branch parts provided on the second surface may preferably be disposed so as not to overlap each other in at least a portion thereof, as viewed in a normal direction to the first surface. Accordingly, the branch parts provided on the top surface of the vibration arm and the branch parts provided on the rear surface of the vibration arm can be cut independently from each other by using a laser beam. Therefore, the sensor output can be adjusted with much higher accuracy.

Application Example 9

In the sensor element in accordance with an aspect of the invention, it is preferred that the detection part may have a detection vibration arm that extends from the base part, and vibrates according to a physical quantity applied to the drive vibration arm, and the detection electrode may be provided on the detection vibration arm. Accordingly, the detection electrode can secure a large electrode area. Therefore, the detection sensitivity of the sensor element can be improved.

Application Example 10

Another embodiment of the invention pertains to a method for manufacturing a sensor element. The sensor element includes a base part; a drive vibration arm for drive vibration that extends from the base part; a vibration arm that extends from the base part and vibrates in response to drive vibration of the drive vibration arm; and a detection part including a detection electrode that outputs a signal according to a physical quantity applied to the drive vibration arm. The vibration arm has an electrode that is electrically connected to the detection electrode and generates a charge in a reverse polarity with respect to a charge generated from the detection electrode when no physical quantity is applied to the drive vibration arm, and the electrode includes a common part provided along an extension direction of the vibration arm and a plural of branch parts branching out from the common part. In accordance with an aspect of the embodiment, the method includes adjusting the charge to be generated at the electrode by cutting the plural branch parts midway or the common part midway. According to the method for manufacturing a sensor element, excellent detection sensitivity can be readily and securely exhibited.

Application Example 11

In the method for manufacturing a sensor element in accordance with an aspect of the invention, it is preferred that the method may include, before performing the charge adjustment, measuring a charge generated at the detection electrode in a state in which the drive vibration arm is vibrated by energization without applying a physical quantity to the drive vibration arm, and adjusting the resonance frequency of the vibration arm. Accordingly, excellent detection sensitivity can be readily and securely exhibited.

Application Example 12

A sensor device in accordance with an embodiment of the invention includes the sensor element in accordance with one of the aspects described above, a circuit for driving the drive vibration arm, and a circuit for detecting an output from the detection electrode. Accordingly, a sensor device with excellent detection sensitivity can be provided at low cost.

Application Example 13

An electronic apparatus in accordance with an embodiment of the invention has the sensor element in accordance with at least one of the aspects described above. Accordingly, an electronic apparatus having excellent reliability can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Sensor elements, characteristic adjustment methods for the sensor elements, sensor devices and electronic apparatuses in accordance with embodiments of the invention will be described below with reference to the accompanying drawings.

First Embodiment

A first embodiment of the invention will be described.FIG. 1is a schematic cross-sectional view briefly showing the composition of a sensor device (an electronic device) in accordance with the first embodiment of the invention.FIG. 2is a plan view of the sensor device shown inFIG. 1.FIG. 3is a plan view showing a sensor element provided in the sensor device shown inFIG. 1.FIG. 4Ais an enlarged plan view of a drive vibration arm of the sensor element shown inFIG. 3, andFIG. 4Bis a cross-sectional view of the drive vibration arm shown inFIG. 4A.FIG. 5Ais an enlarged plan view of a detection vibration arm of the sensor element shown inFIG. 3, andFIG. 5Bis a cross-sectional view of the detection vibration arm shown inFIG. 5A.FIG. 6Ais an enlarged plan view of an adjustment vibration arm of the sensor element shown inFIG. 3, andFIG. 6Bis a cross-sectional view of the adjustment vibration arm shown inFIG. 6A.FIG. 7is a diagram showing a connection state of detection electrodes and adjustment electrodes in the sensor element shown inFIG. 3.FIG. 8is a diagram for describing the operation of the sensor element shown inFIG. 3.FIG. 9Ais a graph showing leakage output of the detection electrode shown inFIG. 5, andFIG. 9Bis a graph showing output of the adjustment electrode shown inFIG. 6. For the sake of convenience of description,FIGS. 1-7show x-axis, y-axis and z-axis, as mutually orthogonal three axes, the direction in parallel with the x-axis is defined as the “x-axis direction,” the direction in parallel with the y-axis is defined as the “y-axis direction,” and the direction in parallel with the z-axis is defined as the “z-axis direction.” Also, the + side of the z-axis is defined as the “upper” side, and the − side of the z-axis is defined as the “lower” side.

Sensor Device

A sensor device1shown inFIG. 1andFIG. 2is a gyro sensor that detects an angular velocity. The sensor device1may be used for shake compensation for imaging devices, and position detection and position control in vehicles equipped with mobile navigation systems using GPS (Global Positioning System) satellite signals, and the like. The sensor device1has, as shown inFIG. 1andFIG. 2, a sensor element2, an IC chip3, and a package4that houses the sensor element2and the IC chip3. The components forming the sensor device1will be described below.

The sensor element2is a gyro sensor element that detects an angular velocity about one axis. As shown inFIG. 3, the sensor element2has a base part21, a pair of drive vibration arms221and222, a pair of detection vibration arms231and232, a pair of adjustment vibration arms (vibration arms)241and242, a support part25, four connection parts261,262,263and264, drive electrode groups51and52, detection electrode groups53and54, and adjustment electrode groups55and56.

In accordance with the present embodiment, the base part21, the pair of drive vibration arms221and222, the pair of detection vibration arms231and232, the pair of adjustment vibration arms241and242, the support part25, and the four connection parts261,262,263and264are formed in one piece from piezoelectric material. As the piezoelectric material, any material may be used without any particular limitation, but quartz crystal may preferably be used. With the use of quartz crystal, the sensor element2can have excellent characteristic.

The quartz crystal has X-axis called “electrical axis,” Y-axis called “mechanical axis,” and Z-axis called “optical axis.” The base part21, the pair of drive vibration arms221and222, the pair of detection vibration arms231and232, the pair of adjustment vibration arms241and242, the support part25, and the four connection parts261,262,263and264may be formed by etching a substrate of quartz crystal having the Z-axis in the thickness direction and having a plane surface in parallel with the X-axis and the Y-axis. The thickness of the substrate is appropriately set according to an oscillation frequency (resonance frequency), outer size, workability, and the like of the sensor element2. In an example to be described below, the base part21, the pair of drive vibration arms221and222, the pair of detection vibration arms231and232, the pair of adjustment vibration arms241and242, the support part25, and the four connection parts261,262,263and264are formed in one piece from quartz crystal.

The base part21is supported on the support part25through the four connection parts261,262,263and264. The four connection parts261,262,263and264each has an elongated shape, having one end connected to the base part21, and another end connected to the support part25. The drive vibration arms221and222each extend in the y-axis direction (+y direction) from the base part21. Also, the drive vibration arms221and222each extend along the Y-axis of quartz crystal. Further, each of the drive vibration arms221and222has a cross section in a rectangular shape composed of a pair of sides in parallel with the x-axis and a pair of sides in parallel with the z-axis. Further, the drive electrode group51is provided on the drive vibration arm221and, similarly, the drive electrode group52is provided on the drive vibration arm222.

Here, the drive electrode group51will be described as representative of the drive electrode groups. Note that the drive electrode group52is generally the same as the drive electrode group51, and therefore its description will be omitted. The drive electrode group51, as shown inFIGS. 4A and 4B, is formed from a drive electrode511provided on the top surface of the drive vibration arm221, a drive electrode512provided on the lower surface of the drive vibration arm221, a drive electrode513provided on one of the side surfaces (on the left side inFIG. 4B) of the drive vibration arm221, and a drive electrode514provided on the other of the side surfaces (on the right side inFIG. 4B) of the drive vibration arm221.

The drive electrode511and the drive electrode512are electrically connected to each other via wires (not shown) to have the same potential. Also, the drive electrode513and the drive electrode514are electrically connected to each other via wires (not shown) to have the same potential. The drive electrodes511and512are electrically connected to a terminal57aprovided on the support part25shown inFIG. 3via wires (not shown). Also, the drive electrodes513and514are electrically connected to a terminal57bprovided on the support part25shown inFIG. 3via wires (not shown).

The detection vibration arms231and232each extend in the y-axis direction (−y direction) from the base part21. Also, the detection vibration arms231and232each extend along the Y-axis of quartz crystal. Further, the detection vibration arms231and232each have a cross section in a rectangular shape composed of a pair of sides in parallel with the x-axis and a pair of sides in parallel with the z-axis. These detection vibration arms231and232vibrate according to a physical quantity applied to the drive vibration arms221and222, respectively.

Further, the detection electrode group53is provided on the detection vibration arm231and, similarly, the detection electrode group54is provided on the detection vibration arm232. In this manner, the detection electrode groups53and54are provided on the detection vibration arms231and232that are provided independently of the drive vibration arms221and222, such that the detection electrodes of the detection electrode groups53and54can each have a greater electrode area (the area of a portion that functions as an electrode). Therefore, the detection sensitivity of the sensor element2can be improved. Note that the detection vibration arm231and the detection electrode group53form a detection section. Similarly, the detection vibration arm232and the detection electrode group54form a detection section.

The detection electrode group53will be described below as representative of the detection electrode groups. Note that the detection electrode group54is generally the same as the detection electrode group53, and therefore its description will be omitted. The detection electrode group53, as shown inFIGS. 5A and 5B, is formed from detection electrodes531and532provided on the top surface of the detection vibration arm231, and detection electrodes533and534provided on the lower surface of the detection vibration arm231. Here, the detection electrodes531and533are provided on one side (on the left side inFIG. 5) in the width direction of the detection vibration arm231, and the detection electrodes532and534are provided on the other side (on the right side inFIG. 5) in the width direction of the detection vibration arm231.

The detection electrode531and the detection electrode534are electrically connected to each other via wires (not shown) to have the same potential. Also, the detection electrode532and the detection electrode533are electrically connected to each other via wires (not shown) to mutually have the same potential. Note that the detection electrodes531and534are paired with each other and the detection electrodes532and533are paired with each other.

The detection electrodes531and534are electrically connected to a terminal57cprovided on the support part25shown inFIG. 3via wires (not shown). Also, the detection electrodes532and533are electrically connected to a terminal57eprovided on the support part25shown inFIG. 3via wires (not shown). Note that the detection electrode group54is electrically connected to terminals57dand57fprovided on the support part25shown inFIG. 3via wires (not shown).

The adjustment vibration arms241and242each extend in the y-axis direction from the base part21. Also, the adjustment vibration arms241and242each extend along the Y-axis of quartz crystal. Further, the adjustment vibration arms241and242each have a cross section in a rectangular shape that is composed of a pair of sides extending in parallel with the x-axis and a pair of sides extending in parallel with the z-axis. Each of the adjustment vibration arms241and242has a rectangular shape, having a front surface (a first surface), a back surface (a second surface), and a pair of side surfaces connecting the first surface and the second surface.

The adjustment vibration arms241and242are provided in parallel with the drive vibration arms221and222described above. In other words, the drive vibration arms221and222and the adjustment vibration arms241and242extend in parallel with one another. Accordingly, when the drive vibration arms221and222and the adjustment vibration arms241and242are composed of quartz crystal, the drive vibration arms221and222and the adjustment vibration arms241and242may be formed to extend in parallel with the Y-axis of quartz crystal, such that the drive vibration arms221and222can be effectively vibrated, and charges can be generated at the adjustment electrodes551-554(to be described below) with relatively simple structure. The adjustment electrode group55is provided on the adjustment vibration arm241and, similarly, the adjustment electrode group56is provided on the adjustment vibration arm242.

The adjustment electrode group55will be described below as representative. Note that description of the adjustment electrode group56will be omitted as it is similar in configuration to the adjustment electrode group55. The adjustment electrode group55is formed from, as shown inFIGS. 6A and 6B, an adjustment electrode551provided on the top surface of the adjustment vibration arm241, an adjustment electrode552provided on the lower surface of the adjustment vibration arm241, an adjustment electrode553provided on one of the side surfaces (on the left side inFIG. 6) of the adjustment vibration arm241, and an adjustment electrode554provided on the other of the side surfaces (on the right side inFIG. 6) of the adjustment vibration arm241.

The adjustment electrode551and the adjustment electrode552are formed in a manner to overlap each other as viewed in a plan view. In other words, the adjustment electrode551and the adjustment electrode552are formed such that their outer shapes coincide with each other as viewed in a plan view. By the adjustment electrode551and the adjustment electrode552thus formed, when branch parts61of the adjustment electrode551are cut, as described below, branch parts (not shown) of the adjustment electrode552corresponding to the cut branch parts61can be cut at the same time.

The adjustment electrode551and the adjustment electrode552are electrically connected to each other via wires (not shown) to have mutually the same potential. Also, the adjustment electrode553and the adjustment electrode554are electrically connected to each other to have mutually the same potential. Note that the adjustment electrodes551and552are paired with each other, and the adjustment electrodes553and554are paired with each other.

The adjustment electrodes551and552are electrically connected through wires (not shown), together with the detection electrodes532and533described above, to the terminal57eprovided on the support part25shown inFIG. 3. Also, the adjustment electrodes553and554are electrically connected through wires (not shown), together with the detection electrodes531and534described above, to the terminal57cprovided on the support part25shown inFIG. 3. Note that the adjustment electrode group56is electrically connected through wires (not shown), together with the detection electrode group54, to the terminals57dand57fprovided on the support part25shown inFIG. 3.

As shown inFIG. 7, the sensor element2having such adjustment electrodes551-554can output a value from the terminal57cas a sensor output of which the amount of charge generated at the detection electrodes531and534and the amount of charge generated at the adjustment electrodes551and552are added together, and a value from the terminal57eas a sensor output of which the amount of charge generated at the detection electrodes532and533and the amount of charge generated at the adjustment electrodes553and554are added together, respectively (which may simply be referred to as a “sensor output”).

Charges generated at the adjustment electrodes551and552and at the adjustment electrodes553and554have reverse polarity with respect to charges generated at the detection electrodes531and534and the detection electrodes532and533, such that at least a part of the charges generated at the detection electrodes531and534and the detection electrodes532and533is cancelled out. By removing a portion of the adjustment electrodes551and552, the sensor output can be adjusted.

Next, the adjustment electrode551will be described below in detail. It is noted that description of the adjustment electrode552will be omitted as it is generally the same as the adjustment electrode551. As shown inFIG. 6A, the adjustment electrode551is equipped with a common part60and a plurality of branch parts61. The common part60is electrically connected to the detection electrodes531and534described above. Also, the plural branch parts61branch out from the common part60and are arranged side by side along the extension direction of the adjustment vibration arm241.

Accordingly, at least one of the branch parts61among the plural branch parts61on the adjustment electrodes551and552or the common part60may be cut midway, whereby the charge between the adjustment electrodes551and552and the adjustment electrodes553and554can be reduced, and thus the sensor output can be adjusted. For example, the sensor output can be adjusted (corrected) such that the sensor output in the state in which no physical quantity is applied to the sensor element2(hereafter also referred to as a “zero point output”) becomes zero.

In particular, the plurality of branch parts61branch out from the common part60, such that, even when any arbitrary one of the branch parts61is cut, the remaining portion of the branch parts61can maintain their electrically connected state with the common part60. In other words, the electrode area of the adjustment electrode515can be reduced by the amount of the arbitrary one of the branch parts61cut among the plural branch parts61. Further, the plural branch parts61are arranged side by side along the extension direction of the adjustment vibration arm241, such that the sensor output can be readily and highly accurately adjusted according to the position and the number of the branch parts61to be cut.

In accordance with the present embodiment, the common part60extends in the extension direction of the adjustment vibration arm241, and the plural branch parts61branch out at mutually different multiple locations in the length direction of the common part60. Accordingly, the structure of the adjustment electrodes551can be simplified. In the present embodiment, as shown inFIG. 6A, the common part60is eccentrically located to one side in the width direction of the adjustment vibration arm241as viewed in a plan view (as viewed in the z-axis direction). Also, the common part60is formed to have a narrow width, such that the common part60can be cut midway with relative ease.

Also, each of the plural branch parts61has a narrow part62having a narrow width formed on the side of the common part60, and a wide part63having a greater width on the opposite side of the common part60. As each of the plural branch parts61has the narrow part62and the wide part63, the adjustment electrode551can secure a large electrode area before adjustment (before the common part60or the branch parts61are cut midway), a wider adjustment range can be secured for adjusting the sensor output through cutting the common part60or the branch parts61midway. Also, mid portions of the branch parts61can be cut with relative ease, as each of the branch parts61has the narrow part62.

Also, the plural narrow parts62are provided in parallel with one another. Also, each of the plural narrow parts62extends in a direction orthogonal to the extension direction of the adjustment vibration arm241, in other words, extends in the x-axis direction. Also, the plural branch parts61are formed to have mutually the same dimensions. Also, the plural branch parts61are arranged at equal pitches in the extension direction of the adjustment vibration arm241, in other words, in the y-axis direction.

When a drive signal is applied between the terminal57aand the terminal57bin the sensor element2thus configured, as shown inFIG. 8, the drive vibration arm221and the drive vibration arm222flexurally vibrate (are driven to vibrate) in a manner to move closer to or separated from each other. More specifically, a state in which the drive vibration arm221flexes in a direction indicated by an arrow A1shown inFIG. 8and the drive vibration arm222flexes in a direction indicated by an arrow A2shown inFIG. 8, and a state in which the drive vibration arm221flexes in a direction indicated by an arrow B1shown inFIG. 8and the drive vibration arm222flexes in a direction indicated by an arrow B2shown inFIG. 8are alternately repeated.

When an angular velocity ω about the y-axis is applied to the sensor element2in a state in which the drive vibration arms221and222are driven to vibrate, the drive vibration arms221and222flexurally vibrate in mutually opposite sides in the z-axis direction by Coriolis force. Due to this flexural vibration, the detection vibration arms231and232flexurally vibrate (detection-vibrate) in mutually opposite sides in the z-axis direction. More specifically, a state in which the detection vibration arm231flexes in a direction indicated by an arrow C1shown inFIG. 8and the detection vibration arm232flexes in a direction indicated by an arrow C2shown inFIG. 8, and a state in which the detection vibration arm231flexes in a direction indicated by an arrow D1shown inFIG. 8and the detection vibration arm232flexes in a direction indicated by an arrow D2shown inFIG. 8are alternately repeated.

By detecting charges generated at the detection electrode groups53and54due to detection vibration of the detection vibration arms231and232, the angular velocity ω worked on the sensor element2can be obtained. At this moment, the adjustment vibration arms241and242also flexurally vibrate, accompanying to the driving-vibration of the drive vibration arms221and222, in mutually closing or separating directions.

In the sensor element2, when the drive vibration arms221and222each do not have a cross-sectional shape as designed due to, for example, manufacturing variations, a charge that becomes a leakage output S is generated between the detection electrodes531and534and the detection electrodes532and533, as shown inFIG. 9A, in the state in which the drive vibration arms221and224are vibrated by excitation without applying a physical quantity to the sensor element2.

Also, in the sensor element2, in the state in which the drive vibration arms221and224are vibrated by energization, regardless of whether or not a physical quantity is applied to the sensor element2, a charge that becomes an adjustment output T is generated between the adjustment electrodes551and552and the adjustment electrodes553and554. Because the leakage output S and the adjustment output T have mutually reversed polarities, the zero point output of the sensor element2can be adjusted to zero by setting an absolute value of the adjustment output T equal to an absolute value of the leakage output S.

Accordingly, by removing a portion of the adjustment electrodes551and552, the amount of charge between the adjustment electrodes551and552and the adjustment electrodes553and554is reduced, whereby the sensor output is adjusted. In other words, the method for manufacturing the sensor element2includes a charge adjustment step of adjusting the amount of charge generated at the adjustment electrodes551and552by cutting the branch parts61or the common part60midway.

Here, the charge adjustment step (a method for adjusting the characteristic of the sensor element2) will be described with reference to a specific example. Note that, although the characteristic adjustment will be described below for the detection vibration arm231and the adjustment vibration arm241as representative, the characteristic adjustment is similarly conducted for the detection vibration arm232and the adjustment vibration arm242.FIG. 10is a flow chart showing an example of the method for adjusting the characteristic of a sensor element in accordance with an aspect of the invention, andFIG. 11is a diagram for describing an example of the method for adjusting the characteristic of the sensor element in accordance with an aspect of the invention.

In the method for adjusting the characteristic of the sensor element2, the sensor element2described above is prepared, and the characteristic of the sensor element2is adjusted by cutting at least one of the branch parts61midway among the plural branch parts61of the sensor element2, or the common part60midway. According to the method for adjusting the characteristic of the sensor element2, excellent detection sensitivity can be readily and securely exhibited.

For the characteristic adjustment, the amount of charge between the terminal57cand the terminal57eis measured, and the cutting is performed based on the measurement result. By the characteristic adjustment, excellent detection sensitivity can be readily and securely exhibited. More specifically, as shown inFIG. 10, first, a leakage output (a zero point output) is measured (step S1).

Based on the measurement result, whether coarse adjustment is necessary or not is judged (step S2). More specifically, when the zero point output is at a first set value or greater, it is judged that coarse adjustment is necessary, and when the zero point output is less than the first set value, it is judged that coarse adjustment is not necessary. When it is judged that coarse adjustment is necessary, coarse adjustment is performed (step S3). More specifically, for example, as shown inFIG. 11A, among the plural branch parts61of the adjustment electrode551, a necessary number of the branch parts61located on the side of the base of the adjustment vibration arm241is cut.

Here, the amount of reduction in the adjustment output T resulting from cutting each of the branch parts61may be obtained in advance by experiment and/or calculation, whereby the number and the position of the branch parts61to be cut can be appropriately selected based on the zero point output measured in step S1. Also, the branch parts61may be cut by any appropriate method without any particular limitation, and may be cut by, for example, using a laser beam.

When it is judged that coarse adjustment is necessary, a part or the entirety of a mass adjustment film (not shown) provided on the end portion of the adjustment vibration arm241may be removed according to the necessity, thereby adjusting the resonance frequency of each of the adjustment vibration arms241and243. More specifically, depending on the necessity, before conducting the charge adjustment step, the step of measuring charges generated at the detection electrodes531-534in the state in which the drive vibration arms221and222are vibrated by energization, and the step of adjusting the resonance frequency of the adjustment vibration arm241based on the measurement result may be conducted. Accordingly, the range of adjusting the sensor output can be made wider.

Removal of a portion or the entirety of the mass adjustment film may be conducted by an appropriate method without any particular limitation, and may be conducted by using, for example, a laser beam. After the coarse adjustment, the process returns to step S1again to measure the leakage output (zero point output). Then, measurement of the zero point output and coarse adjustment are alternately repeated until the zero point output becomes less than the first set value.

On the other hand, when it is judged that coarse adjustment is not necessary, a judgment is made as to whether or not fine adjustment is necessary (step S4). More specifically, when the zero point output is at a second set value that is smaller than the first set value or greater, it is judged that fine adjustment is necessary, and when the zero point output is less than the second set value, it is judged that fine adjustment is not necessary.

When it is judged that fine adjustment is necessary, fine adjustment is conducted (step S5). More specifically, for example, as shown inFIG. 11BorFIG. 11C, among the plural branch parts61of the adjustment electrode551, a necessary number of the branch parts61located on the side of the tip of the adjustment vibration arm241are cut. Note thatFIG. 11Billustrates a case where fine adjustment is conducted without conducting coarse adjustment, andFIG. 11Cillustrates a case where fine adjustment is conducted after conducting coarse adjustment. Also,FIGS. 11B and 11Cillustrate a case where the narrow portions62of the branch parts61are cut. However, the common part60may be cut midway, whereby the electrode area of the adjustment electrode551can be reduced by a plurality of the branch portions together at once by one cutting operation.

Here, similar to the coarse adjustment, the amount of reduction in the adjustment output T resulting from cutting each of the branch parts61may be obtained in advance by experiment and/or calculation, whereby the number and the position of the branch parts61to be cut can be appropriately selected based on the zero point output measured in step S1. After the fine adjustment, the process returns to step S1again, to measure the leakage output (zero point output). Then, measurement of the zero point output and fine adjustment are alternately repeated until the zero point output becomes less than the second set value. On the other hand, when it is judged that fine adjustment is not necessary, adjustment of the characteristic of the sensor element2is completed. According to the method of adjusting the characteristic of the sensor element2described above, the coarse adjustment and the fine adjustment described above can be arbitrarily selected and conducted according to the necessity, such that excellent detection sensitivity can be readily and securely exhibited.

An IC chip3shown inFIG. 1andFIG. 2is an electronic component having a function to drive the sensor element2described above, and a function to detect an output (a sensor output) from the sensor element2. The IC chip3is equipped with, although not shown, a drive circuit that drives the sensor element2, and a detection circuit that detects an output from the sensor element2. Also, the IC chip3is provided with a plurality of connection terminals31.

A package4, as shown inFIG. 1andFIG. 2, includes a base member41(a base) having a recessed portion that opens upward, and a lid member42(a lid) that covers the recessed portion of the base member41. By this structure, an inner space is formed between the base member41and the lid member42where the sensor element2and the IC chip3are housed.

The base member41is formed from a flat plate body411(a plate part), and a frame body412(a frame part) that is bonded to an upper surface of the plate body411at an outer peripheral portion thereof. The base member41may be composed of, for example, aluminum oxide sintered compact, quartz crystal, glass or the like. As shown inFIG. 1, the support part25of the sensor element2described above is bonded to the upper surface of the base member41(the surface on the side thereof covered by the lid member42) by a bonding member81such as adhesive composed of, for example, epoxy resin, acrylic resin or the like. By this structure, the sensor element2is supported on and affixed to the base member41.

The IC chip3described above is bonded to the upper surface of the base member41by a bonding member82, such as, adhesive composed of, for example, epoxy resin, acrylic resin or the like. By this structure, the IC chip3is supported on and affixed to the base member41. Furthermore, as shown inFIG. 1andFIG. 2, a plurality of internal terminals71and a plurality of internal terminals72are provided on the upper surface of the base member41.

The plural internal terminals71are electrically connected to the terminals57a-57fof the sensor element2described above via wires comprised of, for example, bonding wires. The plural internal terminals71are electrically connected to the plural internal terminals72via wires (not shown). Also, the plural internal terminals72are electrically connected to the plural connecting terminals31of the IC chip3described above via wires comprised of, for example, bonding wires.

On the other hand, as shown inFIG. 1, the lower surface of the base member41(i.e., the bottom surface of the package4) is provided with a plurality of external terminals73that are used when the package4is mounted on an apparatus (an external apparatus) in which the sensor device1is installed. The plural external terminals73are electrically connected to the internal terminals72described above via internal wires (not shown). Accordingly, the IC chip3and the plural external terminals73are electrically connected to one another.

The internal terminals71and72and the external terminals73are each comprised of, for example, a metalized layer of tungsten (W) or the like, and a metal membrane of laminated films of nickel (Ni), gold (Au) and the like that may be plated thereon. The lid member42is bonded air-tightly to the base member41. Accordingly, the inner space of the package4is air-tightly sealed.

The lid member42may be formed from, for example, the same material as that of the base member41, or made of metal, such as, Kovar,42Alloy, stainless steel or the like. The base member41and the lid member42may be bonded together by an appropriate method without any particular limitation, and may be bonded together by a bonding method using a brazing material, an adhesive composed of setting type resin or the like, or a welding method such as a seam welding, a laser welding or the like.

Such bonding may be conducted in a reduced pressure atmosphere or an inert gas atmosphere, such that the internal space of the package4can be maintained in a reduced pressure state or an inert gas-filled state. By the sensor element2installed in the sensor device1in accordance with the first embodiment described above, excellent detection sensitivity can be readily and securely exhibited. Also, the sensor device1equipped with the sensor element2described above can provide excellent detection sensitivity at low cost.

Second Embodiment

Next, a second embodiment of the invention will be described.FIGS. 12A and 12Bare enlarged plan views showing adjustment vibration arms of a sensor element in accordance with the second embodiment. The sensor element in accordance with the second embodiment is similar to the sensor element in accordance with the first embodiment described above, except that the adjustment electrode has a different shape.

Note that, in the following description of the sensor element of the second embodiment, aspects different from the embodiment described above will be mainly described and description of similar aspects will be omitted. Also, inFIGS. 12A and 12B, the same signs are assigned to the same configurations as those of the embodiment described above. The sensor element in accordance with the second embodiment has an adjustment vibration arm241A, as shown inFIGS. 12A and 12B. Although not shown, similar to the first embodiment described above, the sensor element in accordance with the second embodiment includes a base part, a pair of drive vibration arms and a pair of detection vibration arms, and another adjustment vibration arm pairing with the adjustment vibration arm241A also extends from the base part.

An adjustment electrode group55A is provided on the adjustment vibration arm241A. The adjustment electrode group55A is formed from an adjustment electrode551A provided on the upper surface (top surface) of the adjustment vibration arm241A, an adjustment electrode552A provided on the lower surface (back surface) of the adjustment vibration arm241A, an adjustment electrode553provided on one of the side surfaces of the adjustment vibration arm241A, and an adjustment electrode554provided on the other of the side surfaces of the adjustment vibration arm241A.

The adjustment electrode551A is equipped with a common part60A and a plurality of branch parts61A. Each of the branch parts61A has a narrow part62A formed in a narrow width on the side of the common part60A, and a wide part63A formed in a wider width on the opposite side of the common part60A. Similarly, the adjustment electrode552A is equipped with a common part64and a plurality of branch parts65. Each of the branch parts65has a narrow part66formed in a narrow width on the side of the common part64, and a wide part67formed in a wider width on the opposite side of the common part64.

The adjustment electrodes551A and552A have portions in which the branch parts61A and the branch parts65do not overlap one another as viewed in a plan view. Specifically, among the plural branch parts61A provided on the top surface and the plural branch parts65provided on the back surface being mutually opposite each other through the center axis of the adjustment vibration arm241A, the plural branch parts61A provided on the top surface and the plural branch parts65provided on the back surface are provided not to overlap each other in at least a portion thereof, as viewed in a normal direction to the top surface or the back surface. More specifically, the narrow parts62A and the narrow parts66are formed in a manner not to overlap each other, as viewed in a plan view. By this structure, although the adjustment electrode551A and the adjustment electrode552A face each other through the adjustment vibration arm241A, the branch parts61A of the adjustment electrode551A, and the branch parts65of the adjustment electrode552A can be cut independently from one another by using a laser beam. Accordingly, the sensor output can be adjusted with higher accuracy. By the sensor element in accordance with the second embodiment described above, excellent detection sensitivity can also be readily and securely exhibited.

Third Embodiment

Next, a third embodiment of the invention will be described.FIG. 13is an enlarged plan view showing an adjustment vibration arm of a sensor element in accordance with the third embodiment. The sensor element in accordance with the third embodiment is similar to the sensor element in accordance with the first embodiment described above, except that the adjustment electrode has a different shape.

Note that, in the following description of the sensor element of the third embodiment, aspects different from the embodiments described above will be mainly described and description of similar aspects will be omitted. Also, inFIG. 13, the same signs are assigned to the same configurations as those of the embodiments described above. The sensor element in accordance with the third embodiment has an adjustment vibration arm241B as shown inFIG. 13. Although not shown, similar to the first embodiment described above, the sensor element in accordance with the third embodiment includes a base part, a pair of drive vibration arms and a pair of detection vibration arms, and another adjustment vibration arm paring with the adjustment vibration arm241B also extends from the base part.

An adjustment electrode group55B is provided on the adjustment vibration arm241B. The adjustment electrode group55B is formed from an adjustment electrode551B provided on the upper surface of the adjustment vibration arm241B, an adjustment electrode552B provided on the lower surface of the adjustment vibration arm241B, an adjustment electrode553provided on one of the side surfaces of the adjustment vibration arm241B, and an adjustment electrode554provided on the other of the side surfaces of the adjustment vibration arm241B.

The adjustment electrode551B will be described below in detail. Note that the adjustment electrode552B is similar to the adjustment electrode551B. The adjustment electrode551B is equipped with a common part60B and a plurality of branch parts61B. Each of the branch parts61B has a narrow part62B formed in a narrow width on the side of the common part60B, and a wide part63B formed in a wider width on the opposite side of the common part60B.

The plural wide parts63B include wide parts63B1-63B6provided on the side of the base end of the adjustment vibration arm241B, and a plurality of wide parts63B7-63B18provided on the side of the tip end of the adjustment vibration arm241B. The wide parts63B1-63B18are arranged from the base end side to the tip end side of the adjustment vibration arm241B in the order of the wide part63B1, the wide part63B2, the wide part63B3, the wide part63B4, the wide part63B5, the wide part63B6, . . . , and the wide part63B18.

The width of each of the wide parts63B1-63B6is greater than the width of each of the wide parts63B7-63B18in the y-axis direction. Accordingly, the area (electrode area) in a plan view of each of the wide parts63B1-63B6is greater than the area (electrode area) of each of the wide parts63B7-63B18as viewed in a plan view. Therefore, the amount of reduction in the adjustment output (in other words, the amount of adjustment in coarse adjustment) by cutting the branch part61B having each of the wide parts63B1-63B6can be made greater. Also, the amount of reduction in the adjustment output (in other words, the amount of adjustment in fine adjustment) by cutting the branch part61B having each of the wide parts63B7-63B18can be made smaller. By the sensor element in accordance with the third embodiment described above, excellent detection sensitivity can also be readily and securely exhibited.

Fourth Embodiment

Next, a fourth embodiment of the invention will be described.FIG. 14is an enlarged plan view showing an adjustment vibration arm of a sensor element in accordance with the fourth embodiment. The sensor element in accordance with the fourth embodiment is similar to the sensor element in accordance with the first embodiment described above, except that the adjustment electrode has a different shape.

Note that, in the following description of the sensor element of the fourth embodiment, aspects different from the embodiments described above will be mainly described, and description of similar aspects will be omitted. Also, inFIG. 14, the same signs are assigned to the same configurations as those of the embodiments described above.

The sensor element in accordance with the fourth embodiment has an adjustment vibration arm241C as shown inFIG. 14. Although not shown, similar to the first embodiment described above, the sensor element in accordance with the fourth embodiment includes a base part, a pair of drive vibration arms and a pair of detection vibration arms, and another adjustment vibration arm paring with the adjustment vibration arm241C also extends from the base part.

An adjustment electrode group55C is provided on the adjustment vibration arm241C. The adjustment electrode group55C is formed from an adjustment electrode551C provided on the upper surface of the adjustment vibration arm241C, an adjustment electrode552C provided on the lower surface of the adjustment vibration arm241C, an adjustment electrode553provided on one of the side surfaces of the adjustment vibration arm241C, and an adjustment electrode554provided on the other of the side surfaces of the adjustment vibration arm241C.

The adjustment electrode551C will be described below in detail. Note that the adjustment electrode552C is similar to the adjustment electrode551C. The adjustment electrode551C is equipped with a common part60C and a plurality of branch parts61C. Each of the branch parts61C has a narrow part62C formed in a narrow width on the side of the common part60C, and a wide part63C formed in a wider width on the opposite side of the common part60C.

The plural wide parts63C include wide parts63C1-63C5provided on the side of the base end of the adjustment vibration arm241C, and a plurality of wide parts63C6-63C9provided on the side of the tip end of the adjustment vibration arm241C. In the wide parts63C1-63C5, among two adjacent ones of the wide parts63C, one of the wide parts63C on the tip end side of the adjustment vibration arm241C in the y-axis direction is greater in width than the other wide part63C on the base end side in the y-axis direction. Therefore, the amount of reduction in the adjustment output (in other words, the amount of adjustment in coarse adjustment) by cutting the branch part61C having each of the wide parts63C1-63C5can be made equal to each other, or mutual differences in the amount of reduction can be made smaller. As a result, coarse adjustment can be conducted with ease.

Similarly, in the wide parts63C6-63C9, among two adjacent ones of the wide parts63C, one of the wide parts63C on the tip end side of the adjustment vibration arm241in the y-axis direction is greater in width than the other wide part63C on the base end side in the y-axis direction. By this structure, the amount of reduction in the adjustment output (in other words, the amount of adjustment in fine adjustment) by cutting the branch part61C having each of the wide parts63C6-63C9can be made equal to each other, or mutual differences in the amount of reduction can be made smaller. As a result, fine adjustment can be readily conducted. By the sensor element in accordance with the fourth embodiment described above, excellent detection sensitivity can also be readily and securely exhibited.

Fifth Embodiment

Next, a fifth embodiment of the invention will be described.FIG. 15is an enlarged plan view showing an adjustment vibration arm of a sensor element in accordance with the fifth embodiment. The sensor element in accordance with the fifth embodiment is similar to the sensor element in accordance with the first embodiment described above, except that the adjustment electrode has a different shape.

Note that, in the following description of the sensor element of the fifth embodiment, aspects different from the embodiments described above will be mainly described and description of similar aspects will be omitted. Also, inFIG. 15, the same signs are assigned to the same configurations as those of the embodiments described above. The sensor element in accordance with the fifth embodiment has an adjustment vibration arm241D as shown inFIG. 15. Although not shown, similar to the first embodiment described above, the sensor element in accordance with the fifth embodiment includes a base part, a pair of drive vibration arms and a pair of detection vibration arms, and another adjustment vibration arm paring with the adjustment vibration arm241D also extends from the base part.

An adjustment electrode group55D is provided on the adjustment vibration arm241D. The adjustment electrode group55D is formed from an adjustment electrode551D provided on the upper surface of the adjustment vibration arm241D, an adjustment electrode552D provided on the lower surface of the adjustment vibration arm241D, an adjustment electrode553provided on one of the side surfaces of the adjustment vibration arm241D, and an adjustment electrode554provided on the other of the side surfaces of the adjustment vibration arm241D.

The adjustment electrode551D will be described below in detail. Note that the adjustment electrode552D is similar to the adjustment electrode551D. The adjustment electrode551D is equipped with a common part60D and a plurality of branch parts61D. The common part60D is provided in a center section in the width direction of the adjustment vibration arm241D as viewed in a plan view.

Each of the branch parts61D has a narrow part62D formed in a narrow width on the side of the common part60D, and a wide part63D formed in a wider width on the opposite side of the common part60D. The branch parts61D are provided on one side and the other side in the width direction of the common part60D. By this structure, the common part60D can be prevented or suppressed from functioning as the adjustment electrode551D. Accordingly, adjustment of the sensor output can be readily performed. Also, the adjustment electrode551D before adjustment (before the common part or the branch parts are cut midway) can secure a large electrode area. By the sensor element in accordance with the fifth embodiment described above, excellent detection sensitivity can also be readily and securely exhibited.

Sixth Embodiment

Next, a sixth embodiment of the invention will be described.FIG. 16Ais an enlarged plan view showing an adjustment vibration arm of a sensor element in accordance with the sixth embodiment. The sensor element in accordance with the sixth embodiment is similar to the sensor element in accordance with the first embodiment described above, except that the adjustment electrode has a different shape. Further, the sensor element in accordance with the sixth embodiment is similar to the sensor element in accordance with the fifth embodiment described above, except that the adjustment vibration arm has a different transverse cross-sectional shape.

Note that, in the following description of the sensor element of the sixth embodiment, aspects different from the embodiments described above will be mainly described and description of similar aspects will be omitted. Also, inFIGS. 16A and 16B, the same signs are assigned to the same configurations as those of the embodiments described above.

The sensor element in accordance with the sixth embodiment has an adjustment vibration arm241E as shown inFIGS. 16A and 16B. Although not shown, similar to the first embodiment described above, the sensor element in accordance with the sixth embodiment includes a base part, a pair of drive vibration arms and a pair of detection vibration arms, and another adjustment vibration arm paring with the adjustment vibration arm241E also extends from the base part.

The adjustment vibration arm241E has an H-letter shaped cross section. In a center section in the width direction of the upper surface of the adjustment vibration arm241E, a groove part2411is formed along the y-axis direction. Similarly, in a center section in the width direction of the lower surface of the adjustment vibration arm241E, a groove part2412is formed along the y-axis direction. Each of the groove parts2411and2412has a rectangular cross-sectional shape, and has wall surfaces extending in parallel with the side surfaces of the adjustment vibration arm241E.

An adjustment electrode group55E is provided on the adjustment vibration arm241E. The adjustment electrode group55E is formed from an adjustment electrode551E provided on the upper surface of the adjustment vibration arm241E, an adjustment electrode552E provided on the lower surface of the adjustment vibration arm241E, an adjustment electrode553provided on one of the side surfaces of the adjustment vibration arm241E, and an adjustment electrode554provided on the other of the side surfaces of the adjustment vibration arm241E.

The adjustment electrode551E will be described below in detail. Note that the adjustment electrode552E is similar to the adjustment electrode551E. The adjustment electrode551E is equipped with a common part60E and a plurality of branch parts61E. The common part60E is provided in a center section in the width direction of the adjustment vibration arm241E as viewed in a plan view.

Each of the branch parts61E has a narrow part62E formed in a narrow width on the side of the common part60E, and a wide part63E formed in a wider width on the opposite side of the common part60E. The branch parts61E are provided on one side and the other side in the width direction of the common part60E. In particular, a portion of each of the branch parts61E is provided on the wall surface of the groove part2411(the wall surface extending in parallel with the side surface of the adjustment vibration arm241E). By such a structure, the charge to be outputted from the adjustment electrode551E can be made greater. For this reason, the range of adjusting the sensor output can be made wider. By the sensor element in accordance with the sixth embodiment described above, excellent detection sensitivity can also be readily and securely exhibited.

Seventh Embodiment

Next, a seventh embodiment of the invention will be described.FIG. 17is an enlarged plan view showing an adjustment vibration arm of a sensor element in accordance with the seventh embodiment. The sensor element in accordance with the seventh embodiment is similar to the sensor element in accordance with the first embodiment described above, except that the adjustment electrode has a different shape. Also, the sensor element in accordance with the seventh embodiment is similar to the sensor element in accordance with the fifth embodiment described above, except that the narrow parts of the adjustment electrode have different orientations.

Note that, in the following description of the sensor element of the seventh embodiment, aspects different from the embodiments described above will be mainly described and description of similar aspects will be omitted. Also, inFIG. 17, the same signs are assigned to the same configurations as those of the embodiments described above.

The sensor element in accordance with the seventh embodiment has an adjustment vibration arm241F as shown inFIG. 17. Although not shown, similar to the first embodiment described above, the sensor element in accordance with the seventh embodiment includes a base part, a pair of drive vibration arms and a pair of detection vibration arms, and another adjustment vibration arm paring with the adjustment vibration arm241F also extends from the base part.

An adjustment electrode group55F is provided on the adjustment vibration arm241F. The adjustment electrode group55F is formed from an adjustment electrode551F provided on the upper surface of the adjustment vibration arm241F, an adjustment electrode552F provided on the lower surface of the adjustment vibration arm241F, an adjustment electrode553provided on one of the side surfaces of the adjustment vibration arm241F, and an adjustment electrode554provided on the other of the side surfaces of the adjustment vibration arm241F.

The adjustment electrode551F will be described below in detail. Note that the adjustment electrode552F is similar to the adjustment electrode551F. The adjustment electrode551F is equipped with a common part60F and a plurality of branch parts61F. The common part60F is provided in a center section in the width direction of the adjustment vibration arm241F as viewed in a plan view.

Each of the branch parts61F has a narrow part62F formed in a narrow width on the side of the common part60F, and a wide part63F formed in a wider width on the opposite side of the common part60F. In particular, each of the narrow parts63F extends in a direction inclined with respect to the extension direction of the adjustment vibration arm241F. By such a structure, at the time of cutting the narrow parts62F by a laser beam, the narrow parts62F can be cut by scanning the laser beam in either the x-axis direction or the y-axis direction. Accordingly, the branch parts61F can be readily cut midway. The branch parts61F are provided on one side and the other side in the width direction of the common part60F, respectively. By the sensor element in accordance with the seventh embodiment described above, excellent detection sensitivity can also be readily and securely exhibited.

The sensor device in accordance with any one of the embodiments described above can be implemented and used in various types of electronic apparatuses. Such electronic apparatuses can exhibit excellent reliability.

Electronic Apparatus

Here, examples of an electronic apparatus equipped with an electronic device in accordance with an embodiment of the invention will be described in detail with reference toFIGS. 18-20.

FIG. 18is a perspective view showing the configuration of a mobile (or a notebook) personal computer1100in which an electronic apparatus in accordance with an embodiment of the invention is implemented. As shown inFIG. 18, the personal computer1100is configured with a main body1104equipped with a keyboard1102, and a display unit1106equipped with a display section100. The display unit1106is rotatably supported on the main body1104through a hinge structure. The sensor device1described above that functions as a gyro sensor is built in the personal computer1100.

FIG. 19is a perspective view showing the structure of a portable phone (including a PHS)1200in which an electronic apparatus in accordance with an embodiment of the invention is implemented. As illustrated in the figure, the portable phone1200has plural operation buttons1202, a receiver1204and a mouthpiece1206, and a display section100disposed between the operation buttons1202and the receiver1204. The sensor device1described above that functions as a gyro sensor is built in the portable telephone1200.

FIG. 20is a perspective view showing the structure of a digital still camera1300in which an electronic apparatus in accordance with an embodiment of the invention is implemented. The figure also schematically shows connections with external apparatuses. In contrast to an ordinary analogue camera that exposes a silver halide photographic film to an optical image of an object, the digital still camera1300photoelectrically converts an optical image of an object by an imaging element such as a CCD (Charge Coupled Device), thereby generating an imaging signal (a picture signal).

The digital still camera1300has a case (body)1302. A display section is provided at the rear surface of the case, and is configured to display an image based on the imaging signal provided by the CCD. The display section functions as a viewfinder to display an electronic image of the object. Also, the case1302is provided on its front side with a photo detection unit1304including an optical lens (an imaging optical system), a CCD and the like.

When the user presses a shutter button1306while visually confirming an object image displayed on the display section, imaging signals of the CCD at the moment are transmitted to and stored in a memory1308. The digital still camera1300also includes video-signal output terminals1312and a data-communication input/output terminal1314on a side of the case1302. As shown in the figure, the video-signal output terminals1312are connected to a monitor1430, and the data-communication input/output terminal1314to a personal computer1440, respectively, according to the necessity. With a predetermined operation, the imaging signals can be fed from the memory1308to the monitor1430and the personal computer1440. The sensor device1described above that functions as a gyro sensor is built in the digital still camera1300.

In addition to the personal computer (mobile personal computer) inFIG. 18, the portable phone inFIG. 19, and the digital still camera inFIG. 20, examples of electronic apparatuses in accordance with embodiments of the invention include, for example, self-position detection devices in vehicles, pointing devices, head-mount display devices, ink-jet devices (for example, ink jet printers), laptop personal computers, televisions, video cameras, video-tape recorders, car navigation systems, pagers, electronic organizers (with or without communications capabilities), electronic dictionaries, calculators, electronic game machines, gaming controllers, word processors, workstations, video phones, security monitors, electronic binoculars, POS terminals, medical equipment (such as electronic thermometers, blood pressure meters, blood glucose meters, electrocardiographic equipment, ultrasonic diagnostic equipment, and electronic endoscopes), fish finders, a variety of measuring equipment, a variety of instruments (such as those used for cars, aircrafts, and ships), flight simulators and the like.

Although the sensor elements, methods for adjusting characteristics of the sensor element, sensor devices and electronic apparatuses in accordance with the embodiments of the invention have been described above with reference to the drawings, the invention is not limited these embodiments.

It is noted that the configuration of each of the components in the sensor elements, sensor devices and electronic apparatuses in accordance with the embodiments of the invention can be replaced with any other configuration that exhibits similar functions, and may be additionally provided with any desired configuration. Also, for the sensor elements, sensor devices and electronic apparatuses in accordance with the embodiments of the invention, any arbitrary configurations in each of the embodiments described above may be combined together.

Also, any desired steps may be added to the method for adjusting characteristic of a sensor element in accordance with any one of the embodiments of the invention.

Also, in the embodiments described above, examples in which the invention is applied to H-letter shape tuning fork sensor elements have been described. However, the invention is also applicable to various other types of sensor elements (gyro elements), such as, double-T type, double-ended tuning fork type, trident tuning fork type, comb-tooth type, orthogonal type, and square beam type sensor elements. Also, the number of the drive vibration arms, the detection vibration arms, and the adjustment vibration arms may be one or three or more. Also, the drive vibration arms may also function as detection vibration arms.

The number, the position, the shape and the size of each of the drive electrodes are not limited to the embodiments described above, as long as the drive vibration arms can be vibrated by energization. The number, the position, the shape and the size of each of the detection electrodes are not limited to the embodiments described above, as long as vibration of the drive vibration arms caused by application of a physical quantity can be electrically detected. Also, the number, the position, the shape and the size of each of the adjustment electrodes are not limited to the embodiments described above, as long as charges generated in response to drive vibration of the adjustment vibration arms can be outputted.

The entire disclosure of Japanese Patent Application No. 2011-214427, filed Sep. 29, 2011 is expressly incorporated by reference herein.