351 results about "Differential capacitance" patented technology

A touch sensor is provided. The touch sensor includes at least two capacitive sensing electrodes, each of the at least two capacitive sensing electrodes having a surface area that is smaller than an area of a touch from a user. The at least two capacitive sensing electrodes each include a substrate, a single conductive element formed on the substrate, and electronic circuitry coupled to the at least two capacitive sensing electrodes for measuring a self-capacitance of the at least two capacitive sensing electrodes. A position corresponding to the touch of a user is determined by the electronic circuitry based on a difference of the measured self-capacitance between the at least two capacitive sensing electrodes.

A detection circuit is provided with a differential capacitive sensor and with an interface circuit having a first sense input and a second sense input, electrically connected to the differential capacitive sensor. Provided in the interface circuit are: a sense amplifier connected at input to the first sense input and to the second sense input and supplying an output signal related to a capacitive unbalancing of the differential capacitive sensor; and a common-mode control circuit, connected to the first sense input and to the second sense input and configured to control a common-mode electrical quantity present on the first sense input and on the second sense input. The common-mode control circuit is of a totally passive type and is provided with a capacitive circuit, which is substantially identical to an equivalent electrical circuit of the differential capacitive sensor and is driven with a driving signal in phase opposition with respect to a read signal supplied to the differential capacitive sensor.

A coupled winding cancels parasitic inductance of first and second capacitors. In an EMI filter having common mode capacitors and a differential capacitors, first and second windings cancel parasitic inductance of the common mode and differential capacitors.

Programmable differential capacitance is implemented in equalization circuits. The programmable differential capacitance improves the common mode rejection ratio of circuits processing differential signals of various frequencies and voltage swings. Multiple capacitance devices provide the programmable capacitance, which provides an equalization circuit with different, selectable (i.e., programmable) values of capacitance for boosting the transition speed and strength of differential signals processed by the equalization circuit.

A capacitive pressure sensor includes a electrically conductive, generally piston shaped diaphragm with a flexible base wall configured to deflect under pressure. The diaphragm is generally U-shaped in cross section. The base wall includes an upper, flat sensing surface which acts as a capacitive electrode. The diaphragm further includes a step around a radially-outermost perimeter which is elevated from the flat sensing surface. A sensing electrode body is located on top of the step and creates a capacitive sensing cavity between the sensing surface and the bottom surface of the electrode body. On the bottom surface of the electrode body is formed a center, circular electrode and a ring electrode that surrounds the center electrode. The center electrode and the sensing surface form a variable capacitor which changes with pressure and the ring electrode and the sensing surface form a reference capacitor. A circuit determines a differential capacitance between the variable capacitor and the reference capacitor and generates a pressure signal indicative of the fluid pressure applied to the diaphragm. A spring ring holds the sensing electrode body against the diaphragm when assembled. The diaphragm can be a machined metal part or a sheet metal cup. The sensing electrodes and signal generating circuit can take the form of a hybrid circuit.

The invention provides a micro-electromechanical system (MEMS) triaxial accelerometer and a manufacturing method thereof. The MEMS triaxial accelerometer comprises a sensitive device layer, an upper cover board layer and a lower supporting body layer, wherein clearances are reserved between the sensitive device layer and the upper cover board layer as well as between the sensitive device layer and the lower supporting body layer; the sensitive device layer comprises a supporting frame body, an elastic beam, three independent sensitive mass blocks, movable comb teeth, fixed comb teeth and an electrode; the three independent sensitive mass blocks in the sensitive device layer are used for detecting acceleration signals of three axes X, Y and Z respectively; an acceleration sensor in each direction is hung in the supporting frame body through the corresponding sensitive mass block by the elastic beam which is only sensitive to the detection direction; a plurality of pairs of movable comb teeth are formed on each sensitive mass block by using a body silicon processing technology; a plurality of pairs of fixed comb teeth are correspondingly formed on the supporting frame body to form a pair of differential capacitors serving as sensitive capacitors; and the differential comb tooth capacitors in different directions generate a differential capacitance change in response to the acceleration signals in the corresponding directions.

Methods of measuring displacement of a movable mass in a microelectromechanical system (MEMS) include driving the mass against two displacement-stopping surfaces and measuring corresponding differential capacitances of sensing capacitors such as combs. A MEMS device having displacement-stopping surfaces is described. Such a MEMS device can be used in a method of measuring properties of an atomic force microscope (AFM) having a cantilever and a deflection sensor, or in a temperature sensor having a displacement-sensing unit for sensing a movable mass permitted to vibrate along a displacement axis. A motion-measuring device can include pairs of accelerometers and gyroscopes driven 90° out of phase.

The invention discloses a high accuracy capacitive readout circuit with temperature compensation, belonging to the design field of integrated circuits. The circuit realizes high accuracy capacitive readout owing to the adoption of a chopping modulation technology, and can simultaneously realize temperature compensation by adjusting temperature characteristics of internal voltage reference. The circuit comprises an oscillator, a voltage reference source, a full-differential operational amplification unit, a common-mode operational amplification unit, a low pass filter, a switch device and a digital circuit. The voltage reference source generates a square wave in cooperation with a single-pole double throw switch, and the square wave is applied to an intermediate polar plate of a differential capacitance to be detected in order to implement modulation. The full-differential operational amplification unit and a feedback capacitance constitute a charge integrator to detect a transfer charge formed by the variation of the capacitance to be detected. Demodulation is realized by the switch device and the low pass filter. Both an input end and an output end of the full-differential operational amplification unit are set through a switch cycle. The common-mode operational amplification unit and the feedback capacitance constitute a common-mode feedback loop which is connected with the input end of the full-differential operational amplification unit to play the role of inputting common-mode voltage stably.

The invention relates to a micro machine differential capacitance accelerometer with a symmetrical structure, which is connected with a movable silicon structure component through an anchoring area along the upper direction and the lower direction. Elastic supporting beams of the silicon structure component are divided into an upper layer and a lower layer and distributed between a movable mass block and a fixedly supported frame as well as connected with the movable mass block and the fixedly supported frame; and the round angle transition is adopted at joints of the movable mass block and the fixedly supported frame as well as the beams; both the upper surface and the lower surface of the movable mass block are provided with gas flow guide grooves; and an electrode cover plate can be made of a silicon material. The gas flow guide grooves distributed on both the upper surface and the lower surface of the mass block are beneficial to regulating the squeeze-film damping effect of the accelerometer so as to structurally improve the dynamic characteristic of the surface separated capacitance detection accelerometer. A plurality of the elastic supporting beams of the accelerometer are made of single crystal silicon materials with a single doping concentration, thereby eliminating thermal inconsistency stress caused by adopting different materials and the thermal inconsistency stress caused by different single crystal silicon doping concentrations.

This invention relates to weak signal test technology, specifically it is a kind of difference capacitance sensor test circuit. It solves the problem that the test precision of the exist difference capacitance sensor test circuit is not high, includes the full wave rectifying circuit, the said full wave rectifying circuit includes the integrated amplification circuit U1B and dynatron Q1, the phase reversal end of the integrated amplification U1B links with the output end out2 of the summator by the resistance R21, the in-phase end links with the output end out2 of the summator by the resistance R19,R20, the resistance R22 is set between the phase reversal end and the output end, the connection node of the resistance R19,R20 connects the collector electrode of the dynatron Q1, the base electrode of the dynatron Q1 links with the output end out1 of the waveform generator by the resistance R17, R18, the connection node of the resistance R17, R18 earth by the diode D3. The structure of the invention is in reason, the test precision of the weak signal produced by the difference capacitance sensor, the reliability is high.

The invention discloses a pseudo-differential capacitive successive approximation register analog-digital converter. The analog-digital converter comprises a first capacitor array, a second capacitor array, a calibration capacitor array and a comparator, wherein lower-bit-segment sub-capacitor arrays of the first capacitor array keep single-end structures; a higher-bit first-segment sub-capacitor array of the first capacitor array and the second capacitor array construct a differential structure; and the first capacitor array and the second capacitor array construct a pseudo-differential capacitor array in which single ends are combined with the differential structure. In an analog-digital conversion process, a transition code value is formed after completion of a least-significant differential weight bit, thereby realizing differential-single end transition. An output end of the calibration capacitor array is connected with an output end of the second capacitor array through a coupling capacitor, and the calibration capacitor array is used for calibrating mismatch of capacitors in the pseudo-differential capacitor array and the offset of the comparator. Through adoption of the analog-digital converter, the chip area can be saved; self-calibration can be performed; and the conversion accuracy is increased.

The invention belongs to the field of a micro electro mechanical system, relating to a four-folding beam variable area differential capacitance structure micro-acceleration sensor and a manufacture method thereof. The sensor consists of a movable mass block, paired spring folding beams, an inserting finger-shaped lower electrode and a micro-acceleration sensor outer frame, wherein the front end and the back end of the movable mass block are connected with the acceleration sensor outer frame through the spring folding beams on the action direction of the outer load; the movable mass block, the spring folding beams and the acceleration sensor outer frame are formed into an integral structure; the lower surface of the movable mass block is provided with an upper electrode; a certain gap is formed between the upper electrode and the inserting finger-shaped lower electrode to be formed into a plate differential capacitor; and the upper electrode is boned with the inserting finger-shaped lower electrode through the acceleration sensor outer frame. With the structure, the invention obviously solves the problem of the nonlinearity of the existing variable gap structure, is good for manufacturing follow-up detecting circuits, leads a vibration mode to be better separated, improves the anti-jamming capability of a device, and increases the sensitivity of the sensor.

The invention provides a frame structure differential capacity type speed-up sensor. It etches bonding needed table on the back of the silicon sheet; the glass base sheet forms a fixed block with the bonding needed table; it etches an elastic beam, a quality block and fixed and active electrode pictures, wherein the bonding block comprises upper, lower, left, right and inner bonding blocks; the upper and lower bonding blocks are connected with the elastic beam; the frame sharp quality block is between the two elastic beams; the inner side of the left and right bonding blocks and the two sides of the middle bonding block have fixed electrode; the frame sharp quality block has an active electrode which is matched with the fixed electrode. The upper and lower bonding blocks and each bonding block connected with the fixed electrode use the electrostatic bonding to fix it on the glass base sheet.

The present invention discloses an ultra short baseline extensometer, which relates to an extensometer. The present invention has the structure that one end of a baseline bar (130) is connected with a displacement sensor (110), which is connected with a first base rock (310) through a nulling device (120); the other end of the baseline bar (130) is connected with a calibrater (150) and then connected with a second base rock (320) through a fixed end (160); the displacement sensor (110) is respectively connected with a measurement and control system (200) through the calibrater (150); the displacement sensor (110) is a differential capacitance sensor (211) with an entire seal structure. The baseline of the present invention is not more than 100 cm, the resolving ability is superior to 1 is multiplied by 10 and then minus 10, the mechanical drive does not exist, the calibration is reliable; the extensometer can be arranged vertically; the volume is small, thus the extensometer is suitable for carrying, and adaptable to the flow of the forerunning effect of earthquake and the emergency monitoring; and the extensometer can be generalized to be used on a long baseline extensometer and other micro-displacement measuring devices.

The invention discloses an MDOF (multi-degree of freedom) differential capacitance displacement sensor calibration device. The device comprises a differential capacitance displacement sensing module, a laser interferometry ranging module, a temperature control module and a data processing module, wherein the differential capacitance displacement sensing module comprises a mechanical sensitive probe and a differential capacitance sensing circuit; the mechanical sensitive probe comprises a movable polar plate, an MDOF micrometric displacement table, fixed polar plates and an insulating base; the laser interferometry ranging module comprises a laser, a shielding frame and N interference fringe units distributed in the translation DOF direction; the temperature control module is used for shielding disturbance of outside environment temperature; the laser interferometry ranging module measures displacement of the movable polar plate relative to the fixed polar plates, the differential capacitance displacement sensing module outputs a voltage signal, and a data acquisition and processing system processes data to obtain a scale coefficient when the movable polar plate moves to output voltage of the differential capacitance displacement sensing module in a translation DOF manner, so that the resolution level of the high-precision differential capacitance displacement sensing module with a micron-dimension range is accurately evaluated.

The invention discloses a differential MEMS (Micro-electromechanical Systems) capacitive microphone and a preparation method for the microphone, wherein the capacitive microphone comprises a substrate, a back cavity, an upper electrode plate, a lower electrode plate, a middle electrode plate and a vibrating membrane. An edge of the vibrating membrane is fixedly connected onto the substrate, at least one open pore is arranged on the vibrating membrane, and the back cavity is arranged below the vibrating membrane; the middle electrode plate is arranged between the upper electrode plate and the lower electrode plate, a first capacitor is formed by the upper electrode plate and the middle electrode plate, and a second capacitor is formed by the lower electrode plate and the middle electrode plate; the middle electrode plate is fixedly connected onto the vibrating membrane and used for changing the position of the middle electrode plate when the vibrating membrane is vibrated along with a sound, so that capacitance values of the first capacitor and the second capacitor can be changed; and a differential capacitor pair is formed by the first capacitor and the second capacitor, and is used for an electric connection in a differential mode and can carry out gathering and processing for an electrical signal.