Abstract: A physical quantity detection element includes: a substrate; first and second fixed electrode portions on the substrate; a movable body on the upper portion of the substrate; and a beam on the movable body, the movable body includes a first movable body on a first side of the beam, and a second movable body on a second side of the beam, the first movable body includes a first movable electrode portion facing the first fixed electrode portion and a first mass portion disposed in an opposite direction of the beam from the first movable electrode portion, the second movable body includes a second movable electrode portion facing the second fixed electrode portion, a mass of the first movable body is greater than a mass of the second movable body, and a mass of the first mass portion is greater than a mass of the first movable electrode portion.

Abstract: An acceleration sensor (1) includes a fixed portion (33), a movable portion (31) connected to the fixed portion (33), a lower electrode (11) that is disposed to face a lower surface of the movable portion (31), and an upper electrode (21) that is disposed to face an upper surface of the movable portion (31). A distance in an x-axis direction between an end portion (41) of the lower electrode (11) and the fixed portion (33) is shorter than a distance in the x-axis direction between an end portion (51) of the upper electrode (21) and the fixed portion (33). Further, a distance in the x-axis direction between an end portion (42) of the lower electrode (11) and the fixed portion (33) is shorter than a distance in the x-axis direction between an end portion (52) of the upper electrode (21) and the fixed portion (33).

Abstract: A microelectromechanical systems (MEMS) sensor device with a compound folded tether is disclosed. The compound folded tether connects a movable proof mass to a substrate, and includes folds composed of multiple short segments aligned with each other to form a longer composite segment having multiple breaks along its length. The use of multiple short segments to create a longer composite segment of the folded tether provides the tether with increased stiffness without altering the fundamental resonance frequency of the tether. The increased stiffness can beneficially lower the occurrence of stiction. Moreover, such a tether configuration provides larger separation between the tether's fundamental resonance frequency and higher order resonant mode frequencies, meaning that the higher order modes may be suppressed in typical operation of the MEMS sensor device.

Abstract: An inertia measurement module and three-axis accelerometer, comprising a first pole piece (4) located on a substrate and a mass block (1) suspendingly connected above the substrate via elastic beams (11, 12); the elastic beams (11, 12) includes a first elastic beam (12) and a second elastic beam (11), two ends of the second elastic beams (11) being connected to an anchor point (6) of the substrate, two ends of the first elastic beam (11) being connected to the mass block (1); a center of the first elastic beam (12) and/or the second elastic beam (11) deviates from a center of gravity of the mass block (1); the mass block (1) is further provided with a first movable electrode (9) and a second movable electrode (10) in a Y-axis and an X-axis direction; the movement of one axis in a plane of the inertia measurement module cannot be affected by an eccentric structure feature, such that both X-axis movement and Y-axis movement are linear movements, thus not intensifying an inter-axis coupling, and also not reducin

Abstract: The present invention provides a sensor with a simple structure which can precisely sense movement, etc., the sensor comprising: a head; and a support which is disposed to support one side of the head, wherein the support comprises: a first support portion for supporting the head; a second support portion which supports the head and is spaced apart from the first support portion; a first extension portion which is extended from the first support portion; a second extension portion which is extended from the second support portion; and a sensing portion which senses the deformation of the first extension portion and the second extension portion.

Abstract: A MEMS acceleration device for measurement of the acceleration along three axes. The device includes capacitors, which capacitance changes under the influence of an acceleration acting upon the device. The change of capacitance for acceleration parallel to the substrate are, normally used with distinct capacitors. This device combines capacitors for using the change in capacitance for sensing in two independent and different directions parallel to the substrate thereby reusing the capacitor. Thereby allowing shrinking of the device while maintaining substantially the same sensitivity.

Abstract: A robust microelectromechanical structure that is less prone to internal or external electrical disturbances. The structure includes a mobile element with a rotor suspended to a support, a first frame anchored to the support and circumscribing the mobile element, and a second frame anchored to the support and circumscribing the mobile element between the mobile element and the first frame, electrically isolated from the first frame. The rotor and the second frame are galvanically coupled to have a same electric potential.

Abstract: An acceleration sensor includes a substrate, a support beam, a weight body a stationary section and an engaging section. The weight body is divided into a first weight section and a second weight section based on the support beam as a boundary line, and the first weight section and the second weight section have different weights from each other. The first weight section and the second weight section include a facing section which faces a side of the engaging section opposite to a side facing the support beam. In an X axis direction intersecting the Y axis direction, if a distance between a corner section of the engaging section in the vicinity of one end portion and the support beam is L1 and a distance between the engaging section and the facing section is L2, a relational expression, L1>L2 is satisfied.

Abstract: Implementations of an accelerometer component may include: a first Z proof mass rotatable about a first axis and coupled to an anchor, the first Z proof mass including a first plurality of electrodes. Implementations may include a second Z proof mass rotatable about the first axis and coupled to the anchor, the second Z proof mass including a second plurality of electrodes. An X-axis accelerometer subcomponent may be located within a perimeter of the first Z proof mass, and a Y-axis accelerometer subcomponent may be located within a perimeter of the second Z proof mass. The first plurality of electrodes and the second plurality of electrodes may be symmetrical about each of the first axis, a second axis perpendicular to the first axis, a third axis diagonal to the first axis and second axis, and a fourth axis diagonal to the first axis and second axis.

Abstract: The invention provides a micro-electro-mechanical device which is manufactured by a CMOS manufacturing process. The micro-electro-mechanical device includes a stationary unit, a movable unit, and a connecting member. The stationary unit includes a first capacitive sensing region and a fixed structure region. The movable unit includes a second capacitive sensing region and a proof mass, wherein the first capacitive sensing region and the second capacitive sensing region form a capacitor, and the proof mass region consists of a single material. The connecting member is for connecting the movable unit in a way to allow a relative movement of the movable unit with respect to the stationary unit.

Abstract: A structure for a MEMS device includes a MEMS layer comprising a mass portion and a spring portion, a substrate coupled to the MEMS layer, wherein the substrate comprises a planar region and an stopper region, wherein the MEMS device and the substrate are oriented in a plurality of relative orientations in response to an external force, wherein the spring portion and the stopper region are configured to disengagingly impact when the external force exceeds a first threshold force, wherein the mass portion and the planar region are configured to disengagingly impact when the external force exceeds a second threshold force, and wherein the second threshold force exceeds the first threshold force.

Abstract: A functional element includes: a substrate; a movable body that includes a movable electrode portion; a support portion that supports the movable body; a first fixed electrode portion that is disposed on the substrate and a portion of which faces a first portion as one of portions of the movable body; a second fixed electrode portion that is disposed on the substrate and a portion of which faces a second portion as the other portion of the movable body; and a third fixed electrode portion that is disposed on the substrate and a portion of which faces the first portion. An opening that faces a region of the substrate between the first fixed electrode portion and the third fixed electrode portion is provided in the movable body, and the width of the opening is equal to or more than the width of the region.

Abstract: A vibration element includes a detection signal electrode provided in a detection vibrating arm, a detection signal terminal which is provided in a support portion and electrically connected to the detection signal electrode, and a detection ground terminal provided in the support portion, and the detection ground terminal is disposed between a first connection portion which is a connection portion with a beam portion of the support portion and a second connection portion which is a connection portion with a beam portion, and is provided to extend to the outside of the first connection portion, and the detection signal terminal is provided between the detection ground terminal and an end portion of the support portion.

Abstract: Described example user interface control apparatus includes a first structure, with a first side, conductive capacitor plate structures spaced along a first direction on the first side, a movable second structure with an auxiliary conductive structure, and an interface circuit to provide excitation signals to, and receive sense signals from, the conductive capacitor plate structures to perform a mutual capacitance test and a self-capacitance test of individual ones of the conductive capacitor plate structures to determine a position of the second structure or a user's finger relative to the first structure along the first direction.

Abstract: A microelectromechanical systems (MEMS) device, such as a single axis accelerometer, includes a movable mass suspended from a substrate. The movable mass has a first portion and a second portion. A first spring system interconnects the first portion of the movable mass with the second portion of the movable mass. A second spring system interconnects the first portion with an anchor system. The first spring system enables movement of the second portion of the movable mass in response to a shock event force imposed on the movable mass in a first direction that is orthogonal to a sense direction, wherein the first spring system inhibits movement of the first portion of the movable mass in the first direction in response to the shock event force. However, the first and second movable masses move together in response to an acceleration force in the sense direction.

Abstract: A method for detecting a malfunction or defect of a sensor of a vehicle safety device uses a control unit of the vehicle safety device and at least one self-testing sensor which is separate from the control unit and transmits measuring values to the control unit.

Abstract: A physical quantity sensor has a first movable section, a second movable section that has a rotational moment, which is generated when acceleration is applied, that is different from the first movable section, a movable section that is supported so as to be able to rock about an axis which is positioned between the first movable section and the second movable section, a first detection electrode which is arranged so as to oppose the first movable section, a second detection electrode which is arranged so as to oppose the second movable section, and a frame-form section which is arranged so as to surround at least a portion of the periphery of the movable section in planar view of the movable section and which has the same potential as the movable section.

Abstract: An integrated MEMS system having a MEMS chip, including a MEMS transducer, and at least one IC chip, including MEMS processing circuitry, and additional circuitry to process electrical signals. The MEMS chip can include first and second insulated conducting pathways. The first pathways conduct the MEMS-signals between the transducer and the IC chip, for processing; and the second conducting pathways can extend through the entire thickness of the MEMS chip, to conduct electrical signals to the IC chip, to be processed by additional circuitry.

Abstract: In some exemplary embodiments, a MEMS accelerometer includes a device wafer having a proof mass and a plurality of tracking anchor points attached to a substrate. Each tracking anchor is configured to deflect in response to asymmetrical deformation in the substrate, and transfer mechanical forces generated in response to the deflection to tilt the proof mass in a direction of the deformation.

Abstract: A physical quantity sensor according to the embodiment includes: a substrate; a movable body including a movable electrode portion; and a support which supports the movable body around a first shaft to be displaced, in which, when the movable body is divided into a first portion and a second portion with the first shaft as a boundary, the physical quantity sensor includes a first fixed electrode portion which is disposed on the substrate to oppose the first portion, and a second fixed electrode portion which is disposed on the substrate to oppose the second portion, and a guard portion which suppresses an electrostatic force generated between the movable body and the substrate is provided in an inter-electrode area between the first fixed electrode portion and the second fixed electrode portion, on the substrate.

Abstract: A tunable microwave network and its application in a radio transceiver transmit signal cancellation network is described. The tunable microwave network realizes a large set of reflection coefficients over a predefined area in the complex reflection coefficient plane for the purpose of reflecting a variable cancellation signal which, when properly configured, results in the substantial attenuation of transmit reflection and transmit leakage signal at the radio transceiver receiver input. A relevant building block of the proposed tunable microwave network is a shunt tunable capacitive element coupled to another shunt tunable capacitive element through a phase shifting element with phase shift greater than 30 degrees divided by a quantity substantially similar to the total number of said tunable capacitive elements and less than 60 degrees at a predefined frequency.

Abstract: A method of fabricating a semiconductor device, includes, in part, growing a first layer of oxide on a surface of a first semiconductor substrate, forming a layer of insulating material on the oxide layer, patterning and etching the insulating material and the first oxide layer to form a multitude of oxide-insulator structures and further to expose the surface of the semiconductor substrate, growing a second layer of oxide in the exposed surface of the semiconductor substrate, and removing the second layer of oxide thereby to form a cavity in which a MEMS device is formed. The process of growing oxide in the exposed surface of the cavity and removing this oxide may be repeated until the cavity depth reaches a predefined value. Optionally, a multitude of bump stops is formed in the cavity.

Abstract: A method for closed loop operation of a capacitive accelerometer comprising: a proof mass; first and second sets of both fixed and moveable capacitive electrode fingers, interdigitated with each other; the method comprising: applying PWM drive signals to the fixed fingers; sensing displacement of the proof mass and changing the mark:space ratio of the PWM drive signals, to provide a restoring force on the proof mass that balances the inertial force of the applied acceleration and maintains the proof mass at a null position; detecting when the mark:space ratio for the null position is beyond a predetermined upper or lower threshold; and further modulating the PWM drive signals by extending or reducing x pulses in every y cycles, where x>1 and y>1, to provide an average mark:space ratio beyond the upper or lower threshold without further increasing or decreasing the mark length of the other pulses.

Abstract: A physical quantity sensor includes a movable electrode side fixed section, a first fixed electrode side fixed section which has a first fixed electrode section and a second fixed electrode side fixed section which has a second fixed electrode section, a movable mass section which has a first movable electrode section that has a portion facing the first fixed electrode section and a second movable electrode section that has a portion facing the second fixed electrode section and which is formed in a shape that encloses the movable electrode side fixed section, the first fixed electrode side fixed section, and the second fixed electrode side fixed section in planar view, and an elastic section which connects the movable electrode side fixed section and the movable mass section.

Abstract: A functional device includes a movable body and a supporting section configured to support the movable body via coupling sections extending along a first axis. The supporting section includes a connection region connected to the coupling sections and provided along the first axis and contact regions provided on the outer side of the connection region in plan view and electrically connected to a wire provided on a substrate.

Abstract: A gyroscope includes drive electrodes that drive a drive mass at a drive frequency. A sense mass is responsive to a Coriolis force caused by rotation of the gyroscope and oscillates based on the drive frequency. Electrodes adjacent to the sense mass drive the sense mass at test frequencies. The response to the driving at the test frequencies is measured and a gyroscope failure is identified based on this response.

Abstract: A physical quantity sensor includes a base substrate and an element piece bonded to the base substrate. The element piece includes fixed portions fixed to the base substrate, a first fixed electrode finger supported on the fixed portion, a second fixed electrode finger supported on the fixed portion, a fixed portion that is positioned between the fixed portions and is fixed to the base substrate, a movable portion that is displaceable with respect to the fixed portion, an elastic portion that links the fixed portion and the movable portion, a first movable electrode finger that is supported on the movable portion and that is arranged facing the first fixed electrode finger, and a second movable electrode finger that is supported on the movable portion and is arranged facing the second fixed electrode finger.

Abstract: A MEMS pressure sensor device is provided that can provide both a linear output with regard to external pressure, and a differential capacitance output so as to improve the signal amplitude level. These benefits are provided through use of a rotating proof mass that generates capacitive output from electrodes configured at both ends of the rotating proof mass. Sensor output can then be generated using a difference between the capacitances generated from the ends of the rotating proof mass. An additional benefit of such a configuration is that the differential capacitance output changes in a more linear fashion with respect to external pressure changes than does a capacitive output from traditional MEMS pressure sensors.

Abstract: A gyroscope is driven at a drive frequency and senses a Coriolis force caused by rotation of the gyroscope. The response of the gyroscope to a given Coriolis force may change due to changes in the gyroscope over time. A plurality of test frequencies are applied to the gyroscope, and the response of the gyroscope to those test frequencies is analyzed in order to track changes in the response of the gyroscope. Operational parameters of the gyroscope may be altered in order to compensate for those changes.

Abstract: A physical quantity sensor has a first structure which has a movable section that includes movable electrode fingers, a second structure which includes first fixed electrode fingers that are arranged to oppose the movable electrode fingers, a third structure which includes second fixed electrode fingers that are arranged to oppose the movable electrode fingers, and a first electrostatic capacity forming section that forms an electrostatic capacity between the first structure and the second structure.

Abstract: A sensor device includes a first physical quantity sensor, a drive section adapted to generate a drive signal for driving the first physical quantity sensor with a drive frequency, a second physical quantity sensor, and an output section adapted to generate an output signal based on a signal from the second physical quantity sensor and a signal having a frequency n times (n is an integer equal to or greater than 1) as high as the drive frequency.

Abstract: A MEMS device includes: a substrate; a proof mass suspended over the substrate, the proof mass including at least one proof mass body and a proof mass frame connected to and accommodating the proof mass body, the proof mass frame including at least one self-test frame; and at least one self-test electrode inside the self-test frame, and connected to the substrate; wherein when a voltage difference is applied between the self-test electrode and the self-test frame, the proof mass is driven to have an in-plane movement, and wherein the self-test electrode and the self-test frame do not form a sensing capacitor in between.

Abstract: A detection apparatus includes: a plurality of accelerometers configured to be installed on respective positions of the architectural structure which are different in height from each other and separately measure an acceleration value generated in the architectural structure; and a computer configured to perform computation by using acceleration values measured by the plurality of accelerometers and detect collision of a flying object (airplane) against the architectural structure when a ratio between the acceleration values measured by the plurality of accelerometers exceeds a first threshold value.

Abstract: A rocker device for a micromechanical Z-sensor, including two rocker arms which are mounted around a torsion spring and which are asymmetric relative to the torsion spring; the rocker arms having first perforations; at least one of the rocker arms having at least one opening, a diameter of the first perforations being configured in a defined manner to be smaller than a diameter of the opening; and a cavity for connecting the first perforations to the at least one opening being formed in at least one of the rocker arms.

Abstract: An acceleration sensor includes: a semiconductor substrate that includes a support substrate and a semiconductor layer; a first-direction movable electrode; a second-direction movable electrode; a first-direction fixed electrode; a second-direction fixed electrode; and a support member. The acceleration sensor is configured to detect acceleration in a first direction in the surface direction of the semiconductor substrate and acceleration in a second direction orthogonal to the first direction and parallel to the surface direction.

Abstract: A movable part rotates about a rotation axis, which passes through a support, when an inertial force in a detecting direction is applied to an inertial sensor. The movable part includes a first region and a second region displaced in a direction opposite to a direction of the first region when the inertial force is applied. A second substrate includes first and second detection electrodes opposed to the first and second regions, respectively. The first detection electrode and the second detection electrode are provided symmetrically with respect to the rotation axis. A cavity is provided symmetrically with respect to the rotation axis. In a direction perpendicular to the detecting direction and a direction in which the rotation axis extends, a length from the rotation axis to an end of the first region and a length from the rotation axis to an end of the second region are different.

Abstract: A low-noise and high-sensitivity inertial sensor is provided. On the assumption that a movable portion VU1 and a movable portion VU2 are formed in the same SOI layer, the movable portion VU1 and the movable portion VU2 are mechanically connected to each other by a mechanical coupling portion MCU even while these movable portions are electrically isolated from each other. Thereby, according to a sensor element SE in the invention, it is possible to further suppress a shift between the capacitance of a MEMS capacitor 1 and the capacitance of a MEMS capacitor 2.

Abstract: The invention provides a micro-electro-mechanical device which is manufactured by a CMOS manufacturing process. The micro-electro-mechanical device includes a stationary unit, a movable unit, and a connecting member. The stationary unit includes a first capacitive sensing region and a fixed structure region. The movable unit includes a second capacitive sensing region and a proof mass, wherein the first capacitive sensing region and the second capacitive sensing region form a capacitor, and the proof mass region consists of a single material. The connecting member is for connecting the movable unit in a way to allow a relative movement of the movable unit with respect to the stationary unit.

Abstract: An accelerometer has a movable mass suspended above a substrate, and a variable acceleration capacitor supported by the substrate. The movable mass has a mass anchor securing the mass to the substrate, while the acceleration capacitor has both a stationary finger extending from the substrate, and a movable finger extending from the movable mass. The accelerometer also has a variable stress capacitor, which also includes the stress finger, for determining movement of the mass anchor relative to the substrate.

Abstract: A micromechanical spring including at least two bar sections which, in the undeflected state of the spring, are oriented substantially parallel to one another or are at an angle of less than 45° with respect to one another, and one or more connecting sections which connect the bar sections to one another, wherein the bar sections can be displaced relative to one another in their longitudinal direction, and wherein the spring has, in the direction of its bar sections, a substantially adjustable, in particular linear force-deflecting behavior.

Abstract: An acceleration detector 10 includes a direction vector setting unit 11 for setting a direction vector u in accordance with detection arguments a and b that define a target detection direction in a three-axis rectangular coordinate system of xyz orthogonal to each other; and an inner product computing unit 12 for obtaining a detected acceleration signal v(n) by calculating an inner product of the direction vector u and acceleration signals x(n), y(n) and z(n) on the individual axes observed in the rectangular coordinate system.

Abstract: A system and method for providing a MEMS sensor are disclosed. In a first aspect, the system is a MEMS sensor that comprises a substrate, an anchor region coupled to the substrate, at least one support arm coupled to the anchor region, at least two guiding arms coupled to and moving relative to the at least one support arm, a plurality of sensing elements disposed on the at least two guiding arms to measure motion of the at least two guiding arms relative to the substrate, and a proof mass system comprising at least one mass coupled to each of the at least two guiding arms by a set of springs. The proof mass system is disposed outside the anchor region, the at least one support arm, the at least two guiding arms, the set of springs, and the plurality of sensing elements.

Abstract: An acceleration sensor includes a substrate, a support beam, a weight body a stationary section and an engaging section. The weight body is divided into a first weight section and a second weight section based on the support beam as a boundary line, and the first weight section and the second weight section have different weights from each other. The first weight section and the second weight section include a facing section which faces a side of the engaging section opposite to a side facing the support beam. In an X axis direction intersecting the Y axis direction, if a distance between a corner section of the engaging section in the vicinity of one end portion and the support beam is L1 and a distance between the engaging section and the facing section is L2, a relational expression, L1>L2 is satisfied.

Abstract: A sensor with continuous self test is provided. An exemplary inertial sensor may include one or more self test electrodes so that one or more test signals may be applied to the electrodes during normal operation of the sensor. Normal sensor output may be read and stored during normal operation, when self test signals are typically not applied to the sensor. The normal sensor output provides a baseline for comparison to a sensor offset error detection signal produced when a test signal may be applied to one self test electrode, and also to a sense error detection signal when a test signal may be applied to both self test electrodes.

Abstract: A physical quantity sensor includes: an oscillating body having a support section and a movable section which is connected to the support section through connection portions, in which the movable section has a first movable portion and a second movable portion; a first fixed electrode which is disposed to face the first movable portion; a second fixed electrode which is disposed to face the second movable portion; and a dummy electrode which is disposed to face the second movable portion so as not to overlap the second fixed electrode and has the same potential as potential of the oscillating body, in which the first fixed electrode is disposed such that a portion thereof overlaps the support section when viewed in a plan view.

Abstract: Embodiments relate to an apparatus for determining a sensitivity of a capacitive sensing device having a sensor capacitor with a variable capacitance. The apparatus includes a measurement module and a processor. The measurement module is configured to determine, in response to a first electrical input signal to the sensor capacitor, a first quantity indicative of a first capacitance of the sensor capacitor and to determine, in response to a second electrical input signal to the sensor capacitor, a second quantity indicative of a second capacitance of the sensor capacitor. The processor is configured to determine a quantity indicative of the sensitivity of the sensing device based on the determined first and second quantity.

Abstract: The electronic measurement circuit comprises a measurement sensor with two differential mounted capacitors each comprising a fixed electrode, and a common electrode arranged to move relative to the fixed capacitor electrode to alter the capacitive value when the physical parameter is measured.

Abstract: The invention provides a MEMS device. The MEMS device includes: a substrate; a proof mass, including at least two slots, each of the slots including an inner space and an opening, the inner space being relatively closer to a center area of the proof mass than the opening; at least two anchors located in the corresponding slots and connected to the substrate; at least two linkages located in the corresponding slots and connected to the corresponding anchors; and a multi-dimensional spring structure for assisting a multi-dimensional movement of the proof mass, the multi-dimensional spring structure surrounding a periphery of the proof mass, and connected to the substrate through the linkages and the anchors. The multi-dimensional spring structure includes first and second springs for assisting an out-of-plane movement and an in-plane movement of the proof mass.

Abstract: One embodiment of the invention includes a vibrating-mass gyroscope system. A sensor system includes a substantially planar vibrating-mass including opposite first and second surfaces and electrodes that extend longitudinally in a periodic pattern across the first and/or second surfaces. The electrodes include sets of drive and sense electrodes that are capacitively coupled to respective matching sets of drive and sense electrodes associated with a housing and which are separated from and facing the respective first and second surfaces. A gyroscope controller generates a drive signal provided to one of the array of drive electrodes and the substantially matching array of drive electrodes to provide for in-plane periodic oscillatory motion of the vibrating-mass, and generates a force-rebalance signal that is provided to one of the array of sense electrodes and the substantially matching array of sense electrodes to calculate rotation of the vibrating-mass gyroscope system about an input axis.

Abstract: An acceleration sensor includes a weight portion having a recess section and a solid section, beam portions, a movable electrode provided on the opposite surface of the weight portion from an open surface of the recess section to extend over the recess section and the solid section, a first fixed electrode arranged at the opposite side of the movable electrode from the recess section, and a second fixed electrode arranged at the opposite side of the movable electrode from the solid section. The acceleration sensor detects acceleration using a change in capacitance between the movable electrode and the fixed electrodes caused by rotation of the weight portion. The beam portions are shifted toward the recess section such that an angle between a perpendicular line extending from a gravity center position of the weight portion to the rotation axis and a surface of the movable electrode becomes equal to 45 degrees.