JP5471217B2 - Angular velocity sensor unit and signal detection method thereof - Google Patents

Description

  The present invention relates to an angular velocity sensor unit using Coriolis force and a signal detection method thereof.

  The angular velocity sensor unit has a structure in which a sensor element 1 for detecting an angular velocity and a control IC 2 are housed in a package 3 as shown in FIG. The basic vibration and the detection vibration are the same, such as when the basic vibration is applied in the axial direction and the angular velocity is applied around the detection axis (Z-axis), the Coriolis force acts on the sensor element 1 to excite the vibration in the Y-axis direction. Planar structures are being studied.

  As an element structure of such a sensor element 1, as shown in FIG. 9, a drive arm 5 that is bent in a bilaterally symmetrical manner about the detection axis 4 is disposed, and one main surface of the drive arm 5 is arranged. A detection signal is formed from a drive electrode 6 that fundamentally vibrates the drive arm 5 in the folding direction (X-axis direction), a monitor electrode 7 for detecting the fundamental vibration state of the drive arm 5, and a detection vibration caused by Coriolis force. The sense electrode 8 is appropriately provided.

  Since the detection signal of the sensor element 1 is proportional to the amplitude of the basic vibration, it is important to keep this amplitude constant. Therefore, the control of this amplitude controls the monitor electrode 7 for detecting the basic vibration state of the sensor element 1. The signal level of the drive signal applied to the drive electrode 6 is controlled based on the monitor signal output from.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2006-275878 A

  Each electrode provided on the drive arm 5 has a laminated electrode structure in which the piezoelectric layer 9 is sandwiched between the upper electrode 10 and the lower electrode 11 as shown in FIG. 10, and the lower electrode 11 is grounded and a positive voltage is applied to the upper electrode 10. Is applied to the laminated electrode to generate a compressive force 12 in the laminating direction, and the laminated electrode is stretched. On the contrary, applying a negative voltage generates a tensile force 13 in the laminated electrode to the laminated electrode. Shrinkage occurs in the laminated electrode, and the drive arm 5 of the sensor element 1 shown in FIG. 9 is fundamentally oscillated in the X-axis direction by utilizing this expansion and contraction action.

  However, in order to obtain the fundamental vibration in the X-axis direction, the expansion and contraction action of the drive electrode 6 is used. In this case, the compressive force 12 and the tensile force 13 that are forces in the stacking direction are simultaneously applied to the drive electrode 6. Therefore, unnecessary vibration (hereinafter referred to as Z-axis vibration) is excited in the Z-axis direction (detection axis direction) in addition to the basic vibration in the X-axis direction.

  This Z-axis vibration also forms an unnecessary signal on the monitor electrode 7 that detects the basic vibration of the drive arm 5, so that the output level of the monitor signal output from the monitor electrode 7 is changed. As a result, the level control of the drive signal for controlling the fundamental vibration is adversely affected, and as a result, the detection accuracy of the angular velocity sensor unit is deteriorated.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such problems and suppress deterioration in detection accuracy of an angular velocity sensor unit.

  In order to achieve this object, the present invention provides an angular velocity sensor unit comprising a vibration type sensor element for detecting an angular velocity and a package incorporating an IC for controlling the sensor element. In addition to providing an electrode and sense electrode, a correction electrode is provided on the wiring electrode of the monitor electrode provided on the support arm that supports the drive arm, and the unnecessary signal formed on the monitor electrode by the Z-axis vibration is corrected by the same Z-axis vibration. The structure is such that it is attenuated by a correction signal formed on the electrode.

  With this structure, the present invention can suppress deterioration in detection accuracy of the angular velocity sensor unit.

Exploded perspective view showing angular velocity sensor unit The top view which shows the sensor element which comprises the angular velocity sensor unit of this invention. Schematic diagram showing the basic vibration state of the sensor element Schematic diagram showing the detection vibration state of the sensor element Schematic showing the operating state of the drive electrode against the same basic vibration Schematic diagram showing the detection state of the monitor electrode for the same basic vibration Schematic diagram showing the detection state of the sense electrode for the same detection vibration Schematic showing the Z-axis vibration of the sensor element Top view showing a conventional sensor element Schematic diagram showing the operating principle of the electrodes provided on the sensor element

  Hereinafter, the angular velocity sensor unit of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the structure similar to the conventional thing mentioned above.

  FIG. 1 shows an angular velocity sensor unit, and its basic structure is a vibration type sensor element 1 for detecting an angular velocity inside a package 3, a drive control circuit and a sensor element for applying a drive signal to the sensor element 1. An IC 2 including a detection circuit for processing a detection signal output from 1 is arranged, and the opening of the package 3 is sealed with a lid 14.

  As shown in FIG. 2, the sensor element 1 includes an external connection portion 15 and a support arm 16 extending from the central portion thereof toward the center portion of the sensor element 1, and a weight portion 17 so as to sandwich the support arm 16. Are arranged so that the respective weight portions 17 are connected by a pair of drive arms 5. A drive electrode 6, a sense electrode 8 and a monitor electrode 7, which will be described later, are arranged on the drive arm 5, and the external connection portion 15. The electrode pad 18 and the wiring electrode 19 are connected to each other. Each drive arm 5 connecting the distal end portion of the support arm 16 and the weight portion 17 has a zigzag structure in which a plurality of arm sides 5a and 5b extending in the Y-axis direction are connected in a folded manner.

  Then, by applying the drive signal output from the IC 2 to the drive electrode 6 via the electrode pad 18 and the wiring electrode 19, the weight portion 17 is expanded and contracted in the X-axis direction as shown in FIG. A basic vibration is generated, and a Coriolis force is generated by receiving an angular velocity about the Z-axis direction in the state of the basic vibration, and the Coriolis force causes the drive arm 5 to vibrate in the Y-axis direction as shown in FIG. The deformation of the drive arm 5 due to the vibration in the Y-axis direction is detected by the sense electrode 8 and converted into an electrical signal, and this detection signal is output to the IC 2 via the wiring electrode 19 and the electrode pad 18. The monitor electrode 7 is provided for detecting the amplitude and driving cycle of the driving arm 5 and feeding back the information to the IC 2 to control the driving signal.

  The sensor element 1 has a structure in which the drive electrode 6, the sense electrode 8, and the monitor electrode 7 described above are provided on a substrate made of Si. The structure of each electrode is on the substrate as described with reference to FIG. A laminated electrode composed of a lower electrode 11 made of Pt, a piezoelectric layer 9 made of PZT provided on the lower electrode 11, and an upper electrode 10 made of Au provided on the piezoelectric layer 9. The structure is such that when a positive voltage is applied to the upper electrode 10 with the lower electrode 11 connected to the ground, a compressive force 12 is exerted in the stacking direction and the stacked electrode is stretched, and when a negative voltage is applied to the upper electrode 10, a tensile force is applied in the stacking direction. The force 13 works and shrinkage occurs in the laminated electrode. On the contrary, if the driving arm 5 is bent to contract the stacked electrode, a negative voltage is generated, and if the stacked electrode is extended, a positive voltage is generated.

  And the drive electrode 6 which fundamentally vibrates this sensor element 1 has the bending inflection point so that the arm edge | side 5b arrange | positioned at the weight part 17 side of the drive arm 5 may be shown with a dashed-dotted line, as shown in FIG. The arm is divided into four as a center and arranged on the side close to the weight portion 17 and the diagonal position thereof. When a positive voltage is applied to both the pair of drive electrodes 6, a compressive force is generated and the arm is stretched. The side 5b tries to bend in an S-shape, and when a negative voltage is applied to both sides, a tensile force is generated and shrinkage occurs, and the arm side 5b tries to bend in the opposite direction. Can be fundamentally oscillated in the X-axis direction.

  Further, since the monitor electrode 7 for detecting the fundamental vibration of the drive arm 5 has a bending inflection point at which the arm side 5a reverses the bending direction with respect to the fundamental vibration, as shown in FIG. The arm side 5a is formed in one area divided into four around the inflection point of bending as shown by the alternate long and short dash line so as not to straddle, and generates electricity according to the bending of the arm side 5a due to the fundamental vibration. As a result, a monitor signal is formed.

  Further, as shown in FIG. 7, the sense electrode 8 that forms a detection signal from the detection vibration generated in the sensor element 1 is bent in a bow shape by the Coriolis force. In order to form a detection signal, the sense electrode 8 is eccentrically provided on the right half of the central axis of the arm side 5a. When the arm side 5a bends to the left side in the drawing, the sense electrode 8 is provided on the right half of the arm side 5a. When an extension force is applied to the provided sense electrode 8 to generate a positive voltage and the arm side 5a bends to the right side in the drawing, a contraction force is applied to the sense electrode 8 provided on the right half of the arm side 5a. Is added to generate a negative voltage to form a detection signal.

  When the angular velocity is detected by the angular velocity sensor unit, the basic vibration of the sensor element 1 is basically performed in the XY plane. The drive electrode 6 that excites the basic vibration in the drive arm 5 is illustrated in FIG. 10, the laminated electrode structure of the upper electrode 10, the lower electrode 11, and the piezoelectric layer 9 uses the compressive force 12 and the tensile force 13 generated in the laminating direction by the drive signal, and thus the laminating direction of the laminated electrodes. In addition, the Z-axis vibration is excited, and an unnecessary signal excited by the Z-axis vibration is added to the detection signal output from the monitor electrode 7, resulting in deterioration of the detection accuracy of the angular velocity sensor unit. It was.

  Therefore, in the angular velocity sensor unit of this embodiment, the correction electrode 20 is provided on the wiring electrode 19 that connects the monitor electrode 7 provided on the support arm 16 and the electrode pad 18, and is unnecessary in the monitor electrode 7 during Z-axis vibration. The signal is attenuated by a correction signal generated in the correction electrode 20 by the same Z-axis vibration, and the influence of the Z-axis vibration on the monitor electrode 7 is suppressed.

  That is, as a condition for attenuating the unnecessary signal generated by the Z-axis vibration by the correction electrode 20, the correction electrode 20 does not form a signal with respect to the basic vibration, and the unnecessary signal generated in the monitor electrode 7 by the Z-axis vibration. On the other hand, since the signal of the reverse potential is formed, the correction electrode 20 is on the support arm 16 which becomes an axis of symmetry of the basic vibration and is not easily affected, and in the direction opposite to the deflection of the monitor electrode 7 in the Z-axis vibration. This is the part where bending occurs.

  Specifically, as shown in FIG. 2, the monitor electrode 7 is arranged on the external connection portion 15 side of the arm side 5a, and the auxiliary electrode 20 is arranged on the external connection portion 15 side of the support arm 16, so that FIG. As shown in the figure, when the weight portion 17 vibrates downward due to the Z-axis vibration, the arm side 5a is bent in a concave shape in the portion where the monitor electrode 7 is provided, so that the contraction force acts on the monitor electrode 7, and thus the monitor electrode 7 is negatively affected. A voltage is generated. Further, in the portion where the correction electrode 20 is provided, the support arm 16 is bent in a convex shape and an extension force acts on the correction electrode 20, so that a positive voltage is generated in the correction electrode 20.

  Therefore, the unnecessary signal generated at the monitor electrode 7 due to the Z-axis vibration and the correction signal generated at the correction electrode 20 are signals of opposite potentials, and these signals are connected to the same electrode pad 18 via the wiring electrode 19 as shown in FIG. Therefore, the monitor signal output from the electrode pad 18 is attenuated by an unnecessary signal due to the Z-axis vibration.

  Further, as an element for forming an unnecessary signal with respect to the Z-axis vibration, an unnecessary signal is similarly formed in the wiring electrode 19 in addition to the monitor electrode 7 described above. Therefore, the correction signal formed in the correction electrode 20 is the wiring electrode. The detection accuracy of the angular velocity sensor unit can be further improved by designing the electrodes so as to attenuate including unnecessary signals due to the number 19.

  Thus, in this sensor element 1, the correction electrode 20 does not generate an unnecessary signal for the basic vibration, and a correction signal for attenuating the unnecessary signal generated in the monitor electrode 7 when the Z-axis vibration is generated is corrected electrode 20. Therefore, the detection accuracy of the monitor signal output from the sensor element 1 to the IC 2 is increased, and the basic vibration of the sensor element 1 can be controlled by the monitor signal having a high detection accuracy. As a result, the angular velocity sensor unit is detected. Accuracy can be increased.

  Since unnecessary signals for Z-axis vibration can be suppressed in this way, it is possible to eliminate vibration isolation means such as TAB tape as a countermeasure against disturbance vibration in the Z-axis direction when the sensor element 1 is assembled to the package 3. Become.

  The present invention has an effect of improving the detection accuracy of the angular velocity sensor unit, and is particularly useful in an angular velocity sensor used for electronic devices that require small and highly sensitive characteristics such as a navigation system.

1 Sensor element 2 IC
3 Package 5 Drive Arm 6 Drive Electrode 7 Monitor Electrode 8 Sense Electrode 15 External Connection 16 Support Arm 17 Weight 18 Electrode Pad 19 Wiring Electrode 20 Correction Electrode

Claims (3)

In an angular velocity sensor unit comprising a vibration-type sensor element that detects angular velocity, an IC that performs basic vibration and detection signal processing of the sensor element, and a package incorporating these sensor element and IC,
The sensor element is folded in such a manner that an external connection portion connected to the package, a support arm extending from the external connection portion, one end connected to a tip portion of the support arm and the other end connected to a weight portion. Drive arm, a drive electrode provided in the drive arm for fundamental vibration in the folding direction according to a drive signal output from the IC, and a charge provided in the drive arm for charging by the fundamental vibration A monitor electrode that is formed and output to the IC; a sense electrode that forms a charge when the drive arm vibrates laterally by application of angular velocity; and outputs to the IC; and a plurality of electrode pads provided at the external connection portion And a wiring electrode for connecting the electrode pad and the drive electrode, the sense electrode or the monitor electrode, and connecting the monitor electrode and the electrode pad A correction electrode is provided on the support arm portion of the wiring electrode, and an unnecessary signal generated in the monitor electrode due to bending vibration in a direction orthogonal to the basic vibration and the detection vibration of the angular velocity is generated in the correction electrode due to the bending vibration. A method for detecting a signal of an angular velocity sensor unit, characterized in that the signal is attenuated by a sensor. 2. The signal detection method for an angular velocity sensor unit according to claim 1, wherein an unnecessary signal generated in the wiring electrode connected to the monitor electrode due to flexural vibration is attenuated by a correction signal generated in the correction electrode. In an angular velocity sensor unit comprising a vibration-type sensor element that detects angular velocity, an IC that performs basic vibration and detection signal processing of the sensor element, and a package incorporating these sensor element and IC,
The sensor element is folded in such a manner that an external connection portion connected to the package, a support arm extending from the external connection portion, one end connected to a tip portion of the support arm and the other end connected to a weight portion. Drive arm, a drive electrode provided in the drive arm for fundamental vibration in the folding direction according to a drive signal output from the IC, and provided in the drive arm for detecting the fundamental vibration. A monitor electrode that outputs to the IC; a sense electrode that is provided in the drive arm and outputs an angular velocity detection signal to the IC; a plurality of electrode pads that are provided in the external connection; and the electrode pad and the drive electrode A wiring electrode that connects the sense electrode or the monitor electrode, and the support electrode of the wiring electrode that connects the monitor electrode and the electrode pad. Characterized in that a correcting electrode for attenuating the correction signal by the fundamental vibration and detecting vibration in the direction orthogonal to the bending vibration of the angular velocity beam portion caused by the flexural vibration of the unwanted signals generated in the monitor electrodes Angular velocity sensor unit.

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