An inertial sensor comprising; a central anchor; a proof mass, wherein the proof mass surrounds the central anchor; a flexure; and a plurality of electrodes is disclosed. The flexure has a shape comprising a first plurality of spiral arms, each winding about the central anchor in a first sense, and a second plurality of spiral arms, each winding about the central anchor in a second sense, the second sense being opposite to the first sense Each of the arms are connected between the central anchor and the proof mass. Advantageously, energy lost through anchor losses and thermoelastic dissipation are reduced in this arrangement, resulting in a higher quality factor for the modes of vibration.
G01C 19/5712 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis the devices involving a micromechanical structure
An accelerometer comprising: a frame; a first proof mass suspended from the frame by one or more flexures to move relative to the frame along a first axis; a first resonant element assembly fixed between the frame and the first proof mass, wherein movement of the proof mass along the first axis relative to the frame exerts a strain on the first resonant element that affects its resonant behaviour; a second proof mass suspended from the frame by one or more flexures to move relative to the frame along a second axis, a second resonant element assembly fixed between the frame and the second proof mass, wherein movement of the second proof mass along the second axis relative to the frame exerts a strain on the second resonant element that affects its resonant behaviour; wherein the second proof mass surrounds the first proof mass and the first resonant element assembly.
G01P 15/125 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
An accelerometer comprising: a frame; one or more proof masses suspended from the frame by one or more flexures and movable relative to the frame along a sensing axis; a first resonant element fixed between an anchor on the frame and the one or more proof masses, and extending from the anchor to the one or more proof masses along the sensing axis; a second resonant element fixed between the anchor and the one or more proof masses and extending from the anchor to the one or more proof masses along the sensing axis in a opposite direction to the first resonant element.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
An accelerometer comprising: a frame; one or more proof masses suspended from the frame by one or more flexures and movable relative to the frame along a sensing axis; a resonant element assembly, the resonant element assembly comprising a first resonant element and a second resonant element coupled to one another, the first resonant element connected between the one or more proof masses and the frame, the second resonant element connected between the one or more proof masses and the frame, such that movement of the one or more proof masses relative to the frame along the sensing axis results in one of the first and second resonant elements undergoing compression and the other of the first and second resonant elements undergoing tension; and drive circuitry configured to drive the resonant element assembly and a sensing circuit configured to determine a measure of acceleration.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01P 15/13 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
5.
MULTIPLY ENCAPSULATED MICRO ELECTRICAL MECHANICAL SYSTEMS DEVICE
There is provided a micro electrical mechanical systems device package comprising: a first vacuum enclosure comprising a first enclosure wall; a micro electrical mechanical systems device being positioned within the first vacuum enclosure on a first side of the first enclosure wall; and a second vacuum enclosure, the second side of the first enclosure wall being within the second vacuum enclosure. Advantageously, the first vacuum enclosure is entirely within the second vacuum enclosure.
There is provided an inertial sensor comprising a frame, a resonator assembly fixed to the frame comprising a first and second resonator coupled to one another by a mechanical coupling and a drive means coupled to the resonator assembly for driving the first and second resonators to vibrate. The resonator assembly is configured such that energy is transferred between the first and second resonators through the mechanical coupling. An amount of energy transferred through the mechanical coupling is dependent on the value of an input measurand acting on one of the first and second resonators. The inertial sensor also comprises a pumping means coupled to the resonator assembly for applying a pumping signal to the resonator assembly, the pumping means controlled by electrical circuitry, and a sensor assembly configured to detect the amplitude of oscillation of the first resonator at a first resonant frequency and the amplitude of oscillation of the second resonator at a second resonant frequency. The electrical circuitry is configured to control the pumping means to apply a pumping signal that has a frequency substantially equal to a difference between the first resonant frequency and the second resonant frequency. When the input measurand has the first value, the signal from the pumping means adjusts an amplitude ratio of the amplitudes of oscillation of the first and second resonator detected by the sensor assembly so that the amplitude ratio is within a predetermined amplitude ratio range over an expected range of input measurand values. An output of the inertial sensor is based on the amplitude ratio.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
G01C 19/5755 - Structural details or topology the devices having a single sensing mass
G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
G01P 15/125 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
G05D 19/02 - Control of mechanical oscillations, e.g. of amplitude, of frequency, of phase characterised by the use of electric means
G01P 15/08 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
7.
MULTIPLY ENCAPSULATED MICRO ELECTRICAL MECHANICAL SYSTEMS DEVICE
There is provided a micro electrical mechanical systems device package comprising: a first vacuum enclosure comprising a first enclosure wall; a micro electrical mechanical systems device being positioned within the first vacuum enclosure on a first side of the first enclosure wall; and a second vacuum enclosure, the second side of the first enclosure wall being within the second vacuum enclosure. Advantageously, the first vacuum enclosure is entirely within the second vacuum enclosure.
There is provided a resonant sensor comprising: a substrate; a proof mass suspended from the substrate by one or more flexures to allow the proof mass to move relative to the frame along a sensitive axis; a first and a second resonant element connected between the frame and the proof mass; wherein the proof mass is positioned between the first and the second resonant element along the sensitive axis, and wherein the first and the second resonant elements have a substantially identical structure to one another; and drive and sensing circuitry comprising: a first electrode assembly coupled to first drive circuitry configured to drive the first resonant element in a first mode; a second electrode assembly coupled to second drive circuitry configured to drive the second resonant element in a second mode, different to the first mode; and a sensing circuit configured to determine a measure of acceleration.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01P 15/08 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
G01P 15/13 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
9.
High performance micro-electro-mechanical systems accelerometer with suspended sensor arrangement
The invention provides a resonant sensor comprising: a substrate; one or more proof masses suspended from the substrate to allow for movement of the one or more proof masses along a sensitive axis; a first resonant element having a first end and a second end, the first resonant element extending between the first end and the second end along the sensitive axis, wherein the first end is connected to the one or more proof masses through a non-inverting lever and the second end is connected to the one or more proof masses through an inverting lever; and an electrode assembly positioned adjacent to the first resonant element. A resonant sensor in accordance the invention comprises a resonant element that is suspended between two proof masses or between two portions of a single proof mass, and so is not connected directly to the substrate. This isolates the resonant element from thermal stress that might otherwise be transferred from the substrate.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01P 15/08 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
10.
High performance micro-electro-mechanical systems accelerometer with electrostatic control of proof mass
There is provided a resonant sensor comprising: a substrate; a proof mass suspended from the substrate to allow for relative movement between the proof mass and the substrate along at least one sensitive axis; at least one resonant element coupled to the proof mass; an electrode assembly adjacent to the at least one resonant element; drive and sense circuitry connected to the electrode assembly configured to drive the electrode assembly to cause the at least one resonant element to resonate, wherein a measure of acceleration of the proof mass can be determined from changes in the resonant behavior of the at least one resonant element; at least one substrate electrode on the substrate, adjacent to the proof mass; and electric circuitry connected to the substrate electrode configured to apply a voltage to the substrate electrode providing an electrostatic force on the proof mass. The substrate electrode may be used to provide a number of different functions.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01P 15/08 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
11.
Method of optimising the performance of a MEMS rate gyroscope
A method of tuning a vibratory gyroscope, the method comprising the steps of: a) applying an AC drive signal to the drive electrode, the drive signal comprising a plurality of frequencies; b) sensing the response of the resonator to the drive signal at the first and second sense electrodes; c) determining a frequency of maximum response for the first mode of vibration, and determining a frequency of maximum response for the second mode of vibration; d) deriving a comparison result from a comparison of the frequency of maximum response for the first mode of vibration with the frequency of maximum response for the second mode of vibration; and e) applying a biasing voltage to one or more of the tuning electrodes dependent on the comparison result.
G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
G01C 19/5755 - Structural details or topology the devices having a single sensing mass
12.
Gravimeter or inertial sensor system using a resonant sensor and method of operating a gravimeter or inertial sensor system
A gravimeter or inertial sensor system and method of operating such a system is provided. The system comprises a variable frequency signal source (100, 101, 102) configured to provide first and second signals, a resonant sensor (103) connected to receive the first signal, a phase comparator (111) connected to the output of the resonant sensor and to receive the second signal, and a controller (114) connected to the phase comparator. In a first mode, the controller controls the desired frequency of the signals from the variable frequency signal source based on a value of the phase comparator output signal to lock the frequency of the input signals to a resonant frequency of the resonant sensor. In a second mode, the controller disconnects from the variable frequency signal source and records an open loop output signal indicative of the physical parameter to be measured based on the response of the resonant sensor.
G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01V 7/00 - Measuring gravitational fields or wavesGravimetric prospecting or detecting
13.
Dual and triple axis inertial sensors and methods of inertial sensing
An inertial sensor comprising: a frame; a proof mass suspended from the frame; a pair of first resonant elements electrically coupled to the proof mass, or to an intermediate component mechanically coupled to the proof mass, each first resonant element coupled to an opposite side of the proof mass to the other, the first resonant elements being substantially identical to one another and having substantially identical electrostatic coupling with the proof mass when the sensor is not accelerating; wherein the first resonant elements and proof mass lie substantially in a plane, and wherein movement of the proof mass relative to the first resonant elements orthogonal to the plane alters the electrostatic coupling between the proof mass and the first resonant elements; drive means coupled to the first resonant elements for vibrating each of the first resonant elements; and a sensor assembly for detecting a shift in the resonant frequency of each of the first resonant elements; and processing means for summing the shifts of each of the first resonant elements to provide a measure of acceleration of the proof mass parallel to a first axis, the first axis being orthogonal to the plane.
G01K 11/26 - Measuring temperature based on physical or chemical changes not covered by group , , , or using measurement of acoustic effects of resonant frequencies
G01P 15/18 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration in two or more dimensions
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01K 7/32 - Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat using change of resonant frequency of a crystal
G01P 15/08 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
14.
MEMS inertial sensor and method of inertial sensing
The invention comprises an inertial sensor comprising a frame, a proof mass, a first resonant element, the first resonant element being fixed to the frame and electrostatically coupled to the proof mass, and a second resonant element, the second resonant element being fixed to the frame, adjacent to the first resonant element such that there is substantially no electrostatic coupling between the second resonant element and the proof mass. A coupling is provided between the first resonant element and the second resonant element. A drive means is coupled to the first and second resonant elements for vibrating the first and second resonant elements and a sensor assembly is provided for detecting the amplitude of vibration of at least one of the resonant elements.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01C 19/5712 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis the devices involving a micromechanical structure
G01C 19/5719 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
15.
MEMS inertial sensor and method of inertial sensing
The invention comprises an inertia! sensor comprising a frame, a proof mass; a first resonant element having a proximal end and a distal end, the first resonant element being fixed to the frame at its proximal end and coupled to the proof mass at its distal end, a second resonant element having a proximal end and a distal end, the second resonant element being fixed to the frame at its proximal end, adjacent to the first resonant element such that there is no coupling between the second resonant element and the proof mass, a means for coupling the first resonant element to the second resonant element; a drive means coupled to the first and second resonant elements for vibrating the first and second resonant elements; and a sensor assembly for detecting the amplitude of vibration of the resonant elements.
G01P 15/097 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
G01C 19/5755 - Structural details or topology the devices having a single sensing mass
G01P 15/18 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration in two or more dimensions
G01P 15/08 - Measuring accelerationMeasuring decelerationMeasuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
patents
