Abstract: A semiconductor substrate surface analysis pre-processing apparatus has a substrate section which holds a decomposition/collecting liquid that is caused to come into contact with the entire surface of a substrate to be surface-analyzed, a substrate transport section which holds the substrate to be surface-analyzed, and which moves the substrate between a substrate carrier and the substrate processing section, a supply and ejection means for the decomposition/collecting liquid, and a processing operation means that performs either ultrasonic or heat processing with respect to the substrate processing section.

Abstract: A method for measuring damping characteristics of a friction member include: relatively pressing a first member as a friction member to be measured against a second member, for relatively sliding with respect to a second member and vibrating, measuring vibration states of the pressed first and second members, and measuring variations in the vibration states of the pressed first and second members and measuring damping characteristics of the friction member to be measured against vibrations by comparing damped amounts based on the variations in the vibration states of the first and second members. The above method and an apparatus therefor enable detailed evaluations of friction member having high performance.

Abstract: In one aspect, the invention provides semiconductor sensor which includes a first single crystal silicon wafer layer. A single crystal silicon structure is formed in the first wafer layer. The structure includes two oppositely disposed substantially vertical major surfaces and two oppositely disposed generally horizontal minor surfaces. The aspect ratio of major surface to minor surface is at least 5:1. A carrier which includes a recessed region is secured to the first wafer layer such that said structure is suspended opposite the recessed region.

Abstract: A single mask, low temperature reactive ion etching process for fabricating high aspect ratio, released single crystal microelectromechanical structures independently of crystal orientation.

Abstract: The present invention relates to methods for determining the uniformity of the piezoelectric effect throughout a piezoelectric material using the time-of-flight of an acoustic wave through the material as a gauge of that uniformity.

Abstract: A sensor (100) includes a fixed gate field-effect transistor (138) that produces a quiescent signal (V.sub.QUIESC1) in a channel (336) when a control signal (V.sub.CONTROL) is applied to a source (332) of the FGFET. A movable gate field-effect transistor (MGFET) (108) produces a sense signal (V.sub.ACCEL) in a channel (316) in response to a physical condition of the sensor when the control signal is applied to a source (312) of the MGFET such that the sense signal is proportional to the quiescent signal. The difference between the currents in the FGFET and MGFET is amplified by a differential amplifier (230) to produce the output signal (V.sub.OUT) of the sensor. The difference between a reference signal (V.sub.RATIO) and the quiescent signal is amplified in an amplifier (206) to produce the control signal that adjusts the output signal to be proportional to the reference signal.

Abstract: An ultrasonic scan assembly is adapted to efficiently and accurately scan a surface and cross-section of a wall of an underground gas pipe with ultrasonic energy transmitted and received by an ultrasonic transducer provided therein. The input pulse applied to the ultrasonic transducer is calibrated so that its width matches the natural mechanical resonant frequency of the ultrasonic transducer. As a result, the energy efficiency of the transducer is maximized and the accuracy of the scan is improved.

Abstract: A semiconductor type yaw rate sensor has a substrate, a beam structure formed from a semiconductor material and having at least one anchor portion disposed on the substrate, a weighted portion located above the substrate a predetermined gap therefrom, and a beam portion which extends from the anchor portion and supports the weighted portion. A movable electrode is formed onto the weighted portion, and a fixed electrode is formed on the substrate in such a manner that the fixed electrode faces the movable electrode. When a drive voltage is applied between the movable electrode and the fixed electrode, the beam structure is forcibly caused to vibrate in a direction that is horizontal relative to a substrate surface plane. In this yaw rate sensor, a strain gauge to monitor forced vibration of the beam structure is formed in the beam portion. As a result, the forced vibration of the beam structure can be monitored with a simple structure.

Abstract: A semiconductor device comprises a semiconductor acceleration sensor having a cantilever made of a semiconductor material, a supporter for supporting the cantilever, and diffused resistors disposed on the cantilever. An acceleration detecting device detects a displacement of the cantilever based on acceleration forces applied to the cantilever and on changes of resistance values of the diffused resistors.

Abstract: A sensor element provided with a silicon substrate having a semiconductor circuit, a sensing-element portion formed on the silicon substrate and connected to the semiconductor circuit, and a cavity portion formed by removing a silicon substrate portion below the sensing-element portion, in which a removal resistance region having resistance against substrate removal is provided in the silicon substrate between the semiconductor circuit and the cavity portion.

Abstract: A micromechanical device or microactuator based upon the piezoelectric, pyroelectric, and electrostrictive properties of ferroelectric thin film ceramic materials such as PZT. The microdevice has a device substrate and a deflectable component. The deflectable component is mounted for deflection on the device substrate and has a sensor/actuator. The sensor/actuator has first and second electrodes and a piezoelectric thin film disposed between the first and second electrodes. The thin film is preferably PZT. The sensor/actuator is disposed on a sensor/actuator substrate. The sensor/actuator substrate is formed of a material selected for being resistive to attack by hydrofluoric acid vapor. The invention also relates to a method for fabricating such micromechanical devices or microactuators.

Abstract: In a semiconductor acceleration sensor, a weight and thin beam parts adjacent to the weight are formed on a substrate, a moving electrode is formed on the weight, and a fixed electrode is formed at a position of the other substrate opposed to the moving electrode. Both the electrodes come in contact with each other and conduct as a result of acceleration on the weight, whereby the semiconductor acceleration sensor operates. The fixed electrode or the moving electrode is formed with a projection toward the opposed electrode and the projection and the electrode come in contact with each other and conduct by action of acceleration with a predetermined spacing held between both the electrodes for preventing occurrence of chattering caused by the electrostatic attraction force between both the electrodes.

Abstract: A quartz crystal resonator is excited in two different modes at the same time such that the mass change and the temperature change can be measured independently. In using such a quartz crystal the change in mass can be calculated accurately and in real time, independent of temperature effects.

Abstract: A resonator (1) is vibrating close to its resonance frequency. The vibration is excited by one or a first transducer (2) connected to an oscillator (11). The vibration is measured by the transducer (2) or a second transducer (3) and stabilized by a phase-locked feedback loop comprising a phase sensitive detector (33), a feedback controller (36), a phase shifter (17) and means (15) to evaluate the measured frequencies. In order to measure the damping of the resonator (1), the phase in the phase shifter (17) is alternately set to two different values. The difference between the frequencies corresponding to these two phase values is a measure for the damping of the system. One or more switches (19, 28, 27) and a gate generator (16) make sure that excitation and measurement do not occur at the same time. Thereby, any cross-talk between driving and sensing transducers is completely eliminated. Also, a single transducer can be used to both excite and measure the vibration.

Abstract: A force sensor device for sensing seismic force due to changes in acceleration or pressure, comprising mass-spring system formed by a resonant flexible plate forming system mass and suspended from a rigid frame by means of at least two beams forming system springs and located at different sides of the plate, the plate, frame and beams being made of a silicon. A vibration excitation device upon application of electric signals at an elected one of a plurality of specific frequencies interacts with the plate to create a corresponding specific vibration mode therein, and a detection device detects any vibration frequency change in the plate due to interaction between a stress field thereon caused by the seismic force and a stress field thereon caused by the vibration mode.

Abstract: A tornado warning system having means for monitoring seismic waves of a predetermined frequency range including long-period seismic waves and short-period seismic waves. The seismic waves are associated with and produced in the ground as a result of an approaching tornado. The warning system comprises means for detecting the seismic waves including the long-period seismic waves and the short-period seismic waves and for providing an electrical output indicative thereof. Circuit means are provided for processing the electrical output to provide an output signal indicative of the long-period seismic waves and the short-period seismic waves. Alarm means are provided for receiving the output signal from the circuit means to generate an alarm to warn of the presence of a tornado.

Abstract: Process for the production of accelerometers using the silicon on insulator method. The process comprises the following stages: a) producing a conductive monocrystalline silicon film on a silicon substrate and separated from the latter by an insulating layer; b) etching the silicon film and the insulating layer up to the substrate in order to fix the shape of the mobile elements and the measuring device; c) producing electric contacts for the measuring devices; d) partial elimination of the insulating layer in order to free the mobile elements, the remainder of the insulating layer rendering integral the substrate and the moving elements.

Abstract: An apparatus for aiming an ultrasonic beam to nondestructively test an object has an ultrasonic transducer for generating the ultrasonic beam having a beam axis and impinging the ultrasonic beam upon the object. The apparatus includes a laser aiming apparatus for directing at least one laser beam having a laser sight line substantially coaxial with the ultrasonic beam axis.The laser aiming apparatus, in one embodiment of the invention, includes a cross-hair apparatus for generating a laser beam cross-hair having a center along the laser sight line. Another embodiment of the present invention provides an ultrasonic mirror apparatus for bending the ultrasonic beam and which has a mirror made of a material that is substantially transparent to the laser beam.

Abstract: An active anti-vibration apparatus detects the motion of an anti-vibration table for supporting equipment with a plurality of sensors and controls actuators on the basis of detection outputs from the sensor. The sensors are arranged such that, when a motion parameter of the anti-vibration table is represented by a vector P, and an output signal group from the plurality of sensors is represented by a vector S, a condition number of a matrix A defined by an equation S=AP established between the vector P and the vector S in accordance with a geometrical arrangement of the plurality of sensors is minimized.

Abstract: A tactile-acoustic transducer comprises a vibrator plate, microphone means and first and second electrode members which are connected to a source of information through a tuneable network. The microphone means are coupled to a computer having display devices and a control output delivering control signals to the tuneable network. Rubbing the vibrator plate with the fingertip of his middle finger allows an operator to assess two different states of the transducer, perceived as "stick" and "non-stick" rubbing conditions, the "stick" condition being accompanied by emission of a characteristic sound and occurring when the network is tuned exactly in accordance with the phenomenon or condition of the source to be detected or measured.

Abstract: A simox wafer includes substrate (1), simox silicon dioxide layer (2) and monocrystalline simox silicon layer (3). An additional silicon nitride layer (5) is deposited on top of silicon layer (3) to allow the fabrication of a monocrystalline beam (4) by selectively etching the dioxide layer (2). The thermal insulating property of the resultant beam (4) offers an ideal site for construction of thermocouples (29), light modulators (60) and active components such as p-n diodes (34), MOS transistors (47) and bipolar transistors.

Abstract: A rotational shock/vibration fixture that adapts a rectilinear shock or vibration apparatus for applying a rotary shock or vibration to a device undergoing test. A rotatable device-mounting-plate, enclosed within a rigid box, receives the device. A pair of diametrically opposed bearings support the box within a frame for movement about a rotation axis. Coil springs stretching between the box and the frame establish a rest orientation for the box with respect to the frame, and dampens oscillations of the box. A reduced backlash linkage between the box to the rectilinear shock or vibration apparatus couples rectilinear movement of the shock or vibration apparatus into rotary shock or vibration of the box. The reduced-backlash linkage may include a lever arm for mechanically amplifying shock applied by the shock or vibration apparatus.

Abstract: A micromechanical accelerometer comprises a mass of monocrystalline silicon in which a substantially symmetrical plate attached to a silicon frame by flexible linkages is produced by selective etching. The plate has a plurality of apertures patterned and etched therethrough to speed further etching and freeing of the plate and flexible linkages, suspending them above a void etched beneath. The plate is capable of limited motion about an axis created by the flexible linkages. An accelerometer comprised of a substantially symmetrical, linkage supported plate configuration is implemented as an angular accelerometer paired with an auxiliary linear accelerometer, which is used to compensate for the linear sensitivity of the angular sensor, to achieve an instrument that is insensitive to linear acceleration and responds to angular acceleration.

Abstract: A method and apparatus for electronically driving an ultrasonic acoustic transducer. The transducer is operable in two modes; in a first mode, the lock-in frequency of the transducer is determined; in a second mode, the lock-in frequency determined in the first mode is used to modulate a tone-burst pulse to drive the transducer in an efficient manner. Operating in the first mode, the lock-in frequency is determined by exciting the transducer with a series of tone bursts, where each tone burst comprises an electronic pulse modulated by a tone of one frequency selected from a range of frequencies, and measuring the response of the transducer to each tone burst. In an alternative embodiment, the excitation of the transducer in the first mode is provided by a signal whose frequency is swept over a range. The response of the transducer is sampled at various times during the sweep. The lock-in frequency is chosen by examining the responses and choosing the frequency which gives the best response.

Abstract: A semiconductor acceleration sensor according to the present invention performs acceleration detection by means of detecting increase or decrease in electrical current flowing between fixed electrodes formed on a semiconductor substrate taking a movable section in a movable state supported on the semiconductor substrate as a gate electrode. Two transistor structures are utilized in this detection. Current between fixed electrodes in one transistor structure increases when the movable section is subjected to acceleration and is displaced. At that time, current between fixed electrodes in the other transistor structure decreases. These two transistor structures are disposed proximately. By means of this proximate disposition, fluctuations in characteristics of both transistors are reduced, and by means of acceleration detection by differential type, temperature characteristics of the two transistors can be canceled favorably.

Abstract: A semiconductor acceleration sensor capable of reducing a leakage current and manufacturing method thereof is disclosed. A beam structure is disposed on a silicon substrate. The beam structure has a movable section, and the movable section is disposed spaced at a prescribed distance above silicon substrate. A movable electrode section is formed in one portion of movable section. Fixed electrodes made of an impurity diffusion layer are formed in silicon substrate to correspond to both sides of a movable electrode section. A peripheral circuit is formed in silicon substrate. The beam structure and the peripheral circuit are electrically connected by an electroconductive thin film, made of polysilicon. Then, when a voltage is applied to the beam structure, and a voltage is applied to both fixed electrodes, an inversion layer is formed, and an electrical current flows between the fixed electrodes.

Abstract: A high precision micromechanical accelerometer comprises a layered structure of five (5) semiconductor wafers insulated from one another by thin oxide layers. The accelerometer is formed by first connecting a coverplate and a baseplate to associated insulating plates. Counter-electrodes, produced by anisotropic etching from the respective insulating plates, are fixed to the coverplate and the baseplate respectively. The counter-electrodes are contactable through the cover or baseplate via contact windows. A central wafer contains a unilaterally linked mass (pendulum) that is also produced by anisotropic etching and which serves as a movable central electrode of a differential capacitor. The layered structure is hermetically sealed by semiconductor fusion bonding. A stepped gradation from the top is formed at a wafer edge region for attaching contact pads to individual wafers to permit electrical contacting of individual wafers. The invention permits fabrication of a .mu.

Abstract: An aftermarket mechanical shock detector for mounting to protected property containing an existing alarm system. The shock detector incorporates a piezoelectric transducer detecting mechanical vibration and generating an electrical vibration signal, and circuitry for comparing the vibration signal to thresholds. The shock detector includes two separately adjustable thresholds. If the vibration signal exceeds either threshold, the shock detector creates an electrical connection between two terminals, thereby triggering a previously-installed alarm circuit to create an alarm.

Abstract: A control device for an alarm system includes a sensor circuit, an amplifier circuit for amplifying a sensor signal from the sensor circuit, a filter circuit for filtering an amplified output of the amplifier circuit, and first and second comparators, each having a reference input and a test input which receives a filtered signal output of the filter circuit. The first reference signal present at the reference input of the first comparator is lower than the second reference signal present at the reference input of the second comparator. The first comparator activates an oscillator circuit to generate an intermittent activating signal when the filtered signal output exceeds the first reference signal. A first alarm signal source presents a first control signal to the alarm system upon reception of the intermittent activating signal from the oscillator circuit.

Abstract: A less expensive small semiconductor pressure sensor in which a pressure sensing element is not displaced by vibration and the like and wire bonding is highly reliably effected includes a pressure sensing element having a diaphragm and a glass base die bonded to a die pad in substantially the same plane as that of an outer lead with a bonding resin. Each of two sets of hanging leads is attached to one of two opposite sides of the die pad to fix the die pad to a package base. With this arrangement, the die pad is securely bonded to the package base to prevent breakage of a metal wire caused by vibration and the like so that a less expensive and smaller semiconductor pressure sensor can be provided.

Abstract: A micromechanical component includes a fixed micromechanical structure having a pair of capacitor plates being formed of one or more conductive layers, and a movable micromechanical structure being formed of a dielectric layer to be introduced into or removed from an interstice between the plates. A capacitance change is obtained through the resilient or freely movable dielectric, so that the component can be inserted as a proportional or a non-proportional force sensor. A microsystem with an integrated circuit and a micromechanical component with a movable dielectric, as well as a production method for the component and the microsystem, are also provided.

Abstract: A monolithic resonator for a vibrating beam device, either an accelerometer or a pressure transducer, includes an outer structure and an inner structure. The outer structure includes a mounting structure, a proof mass or pressure transfer structure and a plurality of flexure beams parallel for the accelerometer and perpendicular for the pressure transducer, extending between the mounting and either proof mass or pressure transfer structure. The inner structure is connected to the outer structure and contains isolator masses, isolator beams and a vibrating beam. The outer structure has a thickness greater than the intermediate thickness of the isolator masses which is in turn thicker than the inner structure thickness of the isolator beams and vibrating beam. The intermediate thickness is independently selected to achieve the ideal mass requirements of the vibration isolation mechanism.

Abstract: Adverse effects due to electrostatic force between a semiconductor substrate and a movable electrode are avoided with a new structure. A movable electrode of beam structure is disposed at a specified interval above a p-type silicon substrate. Fixed electrodes, each composed of an impurity diffusion layer, are disposed on both sides of the movable electrode on the p-type silicon substrate; these fixed electrodes are self-aligningly with respect to the movable electrode. The movable electrode is displaced in accompaniment to the action of acceleration, and acceleration is detected by change (fluctuation) in current between the fixed electrodes generated by means of this displacement. Additionally, an electrode for movable electrode upward-movement use is disposed above the movable electrode, a potential difference is given between the movable electrode and the electrode for movable electrode upward-movement use, and attractive force of the movable electrode to the silicon substrate is alleviated.

Abstract: An electro-mechanical micromachined structure uses bumpers to prevent contact between structures at different potentials. A beam is connected to one or more anchors by flexible suspensions, which permit the beam to move along a predetermined axis relative to one or more plates. The suspension includes at least one bumper positioned so that the bumper will contact another part of the suspension before the beam contacts the plates. The bumper is made from the same material as the suspension, during the same processing step. The bumper is positioned to take advantage of shrinkage or expansion of the beam during processing which forces the bumper closer to its contact point then would otherwise be possible.

Abstract: In an acceleration sensor having movable gates and a movable electrode and having a signal processing portion, the movable gates generate a differential voltage from acceleration in one direction and its output signal is fed back to the movable electrode. The balance of the movable portion is kept using an electrostatic force which cancels the acceleration acting on the movable portion, and signal detection is stabilized using closed loop control. Since signal detection is on a differential basis, acceleration can be detected in only one direction. Since a change in current is detected as a voltage difference, no carrier wave is required. Since MISFETs having movable gates are formed in pairs, there is no influence of temperature drifts. The use of a differential signal similarly cancels the influence of fluctuations of the power supply. Configuration of an acceleration sensor is thus simplified.

Abstract: An electromechanical transducer is provided, and the process for making it utilizes a piezoresistive element or gage which is dielectrically isolated from a gap spanning member and substrate upon which it is supported. The gage of the invention is a force gage and is derived from a sacrificial wafer by a series of etching and bonding steps which ultimately provide a gage with substantially reduced strain energy requirements.

Abstract: A method and apparatus for detecting and measuring gelled material (i.e. gelled pig) as it passes through a tubular by generating ultrasonic pulses at timed intervals which, in turn, are transmitted through said tubular and materials flowing therethrough at a fixed point along said tubular. These pulses are received after they have passed through said tubular and the materials and are processed to identify those pulses which travel through said gelled material as said gelled material passes by said fixed point. From the number of identified pulses, the length of the gelled pig can be determined.

Abstract: A semiconductor yaw rate sensor, which can be structured easily by means of an IC fabrication process, such that a yaw rate detection signal due to a current value is obtained by means of a transistor structure and a method of producing the same is disclosed. A weight supported by beams is disposed at a specified interval from a surface of a semiconductor substrate, and movable electrodes and excitation electrodes are formed integrally with the weight. Fixed electrodes for excitation use are fixed to the substrate in correspondence to the excitation electrodes. Along with this, source electrodes as well as drain electrodes are formed by means of a diffusion layer on a surface of the substrate at positions opposing the movable electrodes, such that drain current changes in correspondence with displacement of the movable electrodes by means of Corioli's force due to yaw rate, and the yaw rate is detected by this current.

Abstract: An aftermarket mechanical shock detector for mounting to protected property containing an existing alarm system. The shock detector incorporates a piezoelectric transducer detecting mechanical vibration and generating an electrical vibration signal, and circuitry for comparing the vibration signal to thresholds. The shock detector includes two separately adjustable thresholds. If the vibration signal exceeds either threshold, the shock detector creates an electrical connection between two terminals, thereby triggering a previously-installed alarm circuit to create an alarm.

Abstract: A method of detecting an underground optical transmission line effectively and efficiently regardless if the optical transmission line is of a non-metallic type or not. The method comprises steps of emitting acoustic vibration from vibration generating means toward an underground area where the optical transmission line 1 is laid while moving the vibration generating means on a road roller 5 on the ground and measuring changes in the intensity of an optical signal being transmitted through the optical transmission line 1 subjected to the vibration and the displacement of the vibration generating means to determine the location of the underground optical transmission line 1 from the distribution of the intensity of the transmitted optical signal.

Abstract: A reactionless single beam vibrating force transducer utilizes counterbalances at opposite ends of the beam that rotate in directions opposite to the ends of the vibrating beam to reduce rotational and normal forces transmitted to the end supports for the beam. The proportions of the counterbalances relative to the size of the beam may be chosen to reduce forces in a direction normal to the beam to zero at the expense of some rotational moments at the end of the beam support, or to reduce moments at the expense of some normal force. The relative amounts of residual rotational moments and normal force can be adjusted to suit particular applications. Flexures may also be utilized to reduce the rotational moments transferred to the beam support even further.

Abstract: A self-exciting optical strain sensor (20) includes dual parallel bridges (22,24) having parallel facing surfaces (32,34). Light energy (38) entering a Fabry-Perot cavity (36) formed by this surfaces (32,34) induces a periodic buildup and release of energy in the cavity (36) which is directly related to the natural resonant frequency of the bridges (22,24). Analysis of the intensity of light emitted (50) from the cavity (36) determines the bridge natural frequency.

Abstract: An apparatus for measuring a thickness of plate material includes a plate material whose thickness is to be measured, a vibration pen to generate a plate wave by applying a vibration to the plate material, a vibration sensor which is disposed at an arbitrary position on the plate material and detects the plate wave which has propagated on the plate material, an extracting circuit to extract different frequency components of the plate wave detected by the vibration sensor, a timer to measure arrival times to the vibration sensor of the signals of the different frequency components extracted by the extracting circuit, and a controller to obtain a thickness of the plate material on the basis of the arrival times measured by the timer and the frequency components corresponding thereto. The extracting circuit is a band pass filter.

Abstract: A planar single-piece measuring string which is designed to oscillate transversely to the plane defining its rest position has two attachment tabs, a resonating string section, two coupling sections connecting the resonating string section to the attachment tabs, and two defined nodal domains where the resonating string section meets the coupling sections. The measuring string includes at each nodal domain a pair of elastic flaps. The elastic flaps extend parallel to the resonating section and participate in the oscillation of the string. The elastic flaps are connected on one side thereof to the nodal domains and the free ends of the flaps are located at a distance opposite each other. The flaps have the same thickness as the other portions of the measuring string.

Abstract: A vibrating sensor comprises an elongated element arranged to vibrate at a frequency dependent upon an external stress applied to the sensor, and an optical fiber for coupling light into an end of the element to excite it into vibration. A light-absorbing layer is provided on a longitudinal surface of the element such that the element will change its configuration, e.g. by bending, as the layer absorbs light and heats that side of the element, this alteration in configuration causing a reduction of radiation which is absorbed so that the element restores. The element may define a Fabry-Perot interferometer between its opposite ends.

Abstract: A method and apparatus for detecting the seismic signal generated by a tornado and providing timely warning of the tornado's approach. The invention involves the use of a geophone or velocity transducer (3) to detect the seismic surface waves generated by the tornado. The output of the geophone passes to the microchip (4) installed with the alarm system (5) within the building (6). Within the microchip the signal passes through the A/D converter (7), to the band-pass filter (8), and then to the signal-to-noise comparator (9). When the signal-to-noise ratio exceeds a specified level, the switch (10) is closed and the alarm (5) is activated.

Abstract: Apparatus is disclosed for measuring the specific force and angular rotation rate of a moving body. A silicon substrate has first and second substantially planar and substantially parallel surfaces. An accelerometer is formed of the substrate and has a force sensing axis. An output signal is provided which is indicative of the moving body along the force sensing axis. The accelerometer is mounted so as to be movable along a vibration axis perpendicular to the force sensing axis. The accelerometer is driven so as to impart a dithering motion thereto of a predetermined frequency along the vibration axis. The accelerometer includes a frame, a proof mass and a hinge interconnected between the frame and the proof mass for rotating the proof mass about a hinge axis when the moving body is subjected to a force along the force sensing axis.

Abstract: Accelerometer having a frame, a proofmass, one or more force sensitive transducers, and a strut interconnecting the transducers with the proofmass and the frame so that forces are applied to the transducers in accordance with movement of the proofmass along the sensitive axis. The transducers and the strut have similar thermal expansion properties and are arranged in such manner that they can expand together with changes in temperature independently of the frame and the proofmass without imposing any significant strain on the transducers. In certain disclosed embodiments, the transducers are formed as a unitary planar structure from a single piece of crystalline quartz material, and the strut is formed of the same material.

Abstract: A resonant strain gauge includes a silicon substrate, a polysilicon flexure beam attached at both ends to the substrate, and a polysilicon rigid cover cooperating with the substrate to enclose the flexure beam within a sealed vacuum chamber. An upper bias electrode is formed on the cover, and a lower bias electrode is formed on the substrate directly beneath and spaced apart from the flexure beam. A drive electrode is formed in or on the beam, centered between the upper and lower bias electrodes transversely with respect to the direction of beam elongation. The upper and lower electrodes are biased at constant voltage levels, of equal magnitude and opposite polarity. The drive electrode, ordinarily biased at ground, is selectively charged by applying an oscillating drive voltage, to cause mechanical oscillation of the beam. A piezoresistor element, formed on the beam, senses beam oscillation and provides a position indicating input to the oscillator circuit that drives the beam.

Abstract: A microaccelerometer is provided which has a silicon substrate bonded to a silicon capping plate and silicon back plate, wherein the bonds between the three silicon wafers are characterized by a relatively low residual stress level over a wide temperature range. The bonds are formed by means of an appropriate adhesive at a relatively low temperature without degradation to the microaccelerometer. The bonds between the silicon wafers also provide stress relief during use and packaging of the microaccelerometer. With this invention, the damping distance for the proof mass of the microaccelerometer is accurately controllable and stop means are provided for preventing excessive deflection of the proof mass in a direction perpendicular to the plane of the microaccelerometer.