Capacitance Patents (Class 340/562)
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Patent number: 5764145Abstract: A capacitive detector is provided which includes an antenna for detecting small capacitive changes in an electric or electromagnetic field surrounding the antenna, and particularly to an alarm system which uses the capacitive detector to generate an alarm signal upon detection of capacitive changes in the generated electric or electromagnetic field. The detector is realized with an antenna connected to an electronic circuitry which generates an electric field around the antenna. The electronic circuitry generates an electric or electromagnetic field around the antenna, builds up a balanced electric field around the antenna, maintains the generated electric or electromagnetic field around the antenna balanced, prevents the detector device from being affected by changes in temperature and humidity, detects small changes in the generated electric field around the antenna, and indicates that a change in the generated electric field has occurred.Type: GrantFiled: June 27, 1996Date of Patent: June 9, 1998Inventors: Goran Hansson, Bo Lindgren, Tommy Soderberg
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Patent number: 5760688Abstract: An improved body sensing device capable of precisely sensing a living body at a standstill by discriminating the living body from other substances than the living body. An oscillator provided with a detection coil oscillates a high frequency signal. As there is no object or exists baggage or the like near the detection coil, the oscillator oscillates and generates a high frequency signal at a high level to be detected by a detector for turning on a transistor of a controller. As there exists a human body near the oscillator, the oscillation stops and the input signal from the detector to the transistor is extremely lowered, so that the transistor is turned off.Type: GrantFiled: May 24, 1996Date of Patent: June 2, 1998Assignee: Omron CorporationInventor: Eiji Kasai
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Patent number: 5757196Abstract: A capacitive proximity or limit switch comprises a capacitive probe having a sensor electrode and a guard electrode. The sensor electrode is connected to an oscillator formed by a feedback system of two operational amplifiers, of which one operational amplifier is configured as a differential amplifier, the other operational amplifier as a voltage follower. The probe electrode is connected to the inverting input of the differential amplifier, in the feedback circuit of which a capacitor is provided, as a result of which the AC gain is determined. An adjustable portion of the output voltage of the differential amplifier is applied to the non-inverting input of the voltage follower, the output of which is connected to the non-inverting input of the differential amplifier to which the guard electrode is connected.Type: GrantFiled: September 26, 1996Date of Patent: May 26, 1998Assignee: Endress + Hauser GmbH + Co.Inventor: Gustav Wetzel
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Patent number: 5748088Abstract: The dielectrophoretic force caused by the non-uniform electric field squared spatial gradient three-dimensional pattern uniquely exhibited by a predetermined type of entity can be detected by locator device. A human operator holds the device in hand to thereby electrically connect to the human operator. The human operator's naturally occurring very low electrical decay time constant is increased through electronic circuitry externally connected to the device. The device is held in a balanced horizontal state, and the operator scans the device in a constant uniform motion back and forth. An antenna extends from the front of the device, and both are acted on by the dielectrophoretic force. This force results in a subsequent resulting torque, acceleration, vibration or any other measurable quantifiable manifestation of the force about the handle's pivot line hence driving the device and its antenna toward the direction and position of any entities of the predetermined type that are within range.Type: GrantFiled: November 27, 1996Date of Patent: May 5, 1998Inventor: Thomas L. Afilani
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Patent number: 5745035Abstract: A motion detecting system including a plurality of transmitter housings. A plurality of motion detector transmitter mechanisms are situated in each of the transmitter housings. Each motion detector transmitter mechanism includes a motion detector adapted to emit a motion signal upon the detection of motion, a transmitter adapted to emit a transmitter activation signal via free space upon the transmission of the motion signal and only during the receipt of power, and a one-shot multivibrator mechanism connected to the motion detector and the transmitter. The one-shot multivibrator mechanism is adapted to transmit power for a predetermined amount of time upon the receipt of the motion signal. Further provided is a receiver unit including a housing and a receiver mechanism. The receiver mechanism includes a receiver adapted to accept the transmitter activation signal via free space.Type: GrantFiled: February 20, 1997Date of Patent: April 28, 1998Inventor: David W. Deyo
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Patent number: 5722686Abstract: An apparatus for controlling an actuatable restraint system (20) in response to a sensed position of an occupant (36) in an occupant compartment of a vehicle includes a variable capacitor (60) mounted relative to a known reference location (30) within the vehicle. The variable capacitor (60) is adapted so that its capacitance value is functionally related to the occupant's position relative to the reference location (30). A controller (50) is coupled to a capacitance sensing circuit (80) for controlling the actuatable restraint (22) in response to the sensed occupant position relative to the reference location.Type: GrantFiled: May 16, 1995Date of Patent: March 3, 1998Assignee: TRW Vehicle Safety Systems, Inc.Inventors: Brian K. Blackburn, Scott B. Gentry, Joseph F. Mazur, Charles E. Steffens, Jr., John E. Bessonen, William M. Jarocha
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Patent number: 5724024Abstract: A device detects whether persons are present on seats, for example of a vehicle. An electric monitoring arrangement with electrodes is associated to each person. The electrodes are provided for sensing the human body, in particular the thorax. Mainly the breathing is processed in an evaluation circuit.Type: GrantFiled: March 13, 1996Date of Patent: March 3, 1998Assignee: Vos Verkehrs-Optimierungs-Systems GmbH & Co.Inventors: Wilhelm Sonderegger, Georg Kuehne, Thomas Hupp
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Patent number: 5705984Abstract: An intrusion detection system. An RF energy source transmits energy into a ransmission cable that has a characteristic impedance subject to change by deformation of the cable. The cable is buried along a path that corresponds to a perimeter to be monitored. When an intruder places weight in the vicinity of the cable, the cable deforms and changes its characteristic impedance. Consequently a portion of energy transmitted into the cable reflects back where time-domain or frequency-domain reflectometry apparatus uses the reflected energy to identify the location of the intrusion along the cable and provide other characteristics of the intruder.Type: GrantFiled: May 10, 1996Date of Patent: January 6, 1998Assignee: The United States of America as represented by the Secretary of the NavyInventor: Douglas H. Wilson
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Patent number: 5675319Abstract: A tamper detection device can determine whether a housing containing a device has been tampered with either by having the housing penetrated or by an attempt to remove a cover from the housing. The tamper detection device may be a capacitor which is placed across a portion of the housing and whose capacitance changes if it is penetrated. The temper detection device may also be a flexible circuit having conductive strips thereon forming a circuit with means to cause an open circuit if the housing is penetrated or the cover removed from the housing.Type: GrantFiled: April 26, 1996Date of Patent: October 7, 1997Assignee: David Sarnoff Research Center, Inc.Inventors: Howard Christopher Rivenberg, Aaron William Levine, Nitin Vithalbhai Desai
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Patent number: 5661462Abstract: A bath overflow alarm comprised of a housing having a pair of slots formed through a lower end thereof. The housing has a waterproof battery chamber therein for active receipt of a battery. The housing is adapted for securement to a bathtub. A pair of water contacts are secured within the housing. An alarm mechanism is secured within the housing disposed above the pair of water contacts. Once water enters into the housing through the slots, the water contacts signal the alarm mechanism which will alert a person as to a dangerous water level.Type: GrantFiled: May 6, 1996Date of Patent: August 26, 1997Inventor: Christopher Shrewsbury-Gee
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Patent number: 5650623Abstract: A perimeter monitoring device is disposed so as to detect passage of objects through a monitored space above a perimeter line and to generate a perimeter signal in correspondence with such a detected passage. The monitoring device includes at least one sensor element disposed along the perimeter line to be monitored and a processing unit coupled to the sensor element so as to detect electrical current generated in the sensor element from the movement of the intruding object past the sensor element. Each sensor element comprises a loop of electrically conductive material that is electrically isolated from the other sensor element, and each of which is separately electrically coupled to the processing unit. The perimeter detection system further comprises an electrical insulation material, such as a mat, that is disposed between the conductive sensor element and the monitored space.Type: GrantFiled: December 4, 1995Date of Patent: July 22, 1997Assignee: General Electric CompanyInventors: Ravi Rajamani, Frederic Ghislain Pla
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Patent number: 5625294Abstract: An apparatus for detecting seated condition for toilet seat which detects whether the change in input voltage of determining circuit, over predetermined time, in response to electrostatic capacity is existed or not. When the change is existed, the present apparatus computes and renews the set value 1 for detecting un-seated condition and the set value 2 for detecting seated condition based on the changed input potential.Accordingly, the present apparatus is the apparatus for detecting whether a human is seated or un-seated on a toilet seat using electrostatic capacity and the present invention can reduce the error in detection caused by the change in electrostatic capacity owing to a person, temperature and humidity.Type: GrantFiled: November 18, 1994Date of Patent: April 29, 1997Assignees: Aisin Seiki Kabushiki Kaisha, Inax CorporationInventors: Shinji Kawai, Mitsugu Nonomura, Yuji Yamaguchi, Seiji Tanaka, Akira Takamata
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Patent number: 5554973Abstract: A proximity sensor of the electrostatic type has a pulse-generating circuit and first and second delay circuits which are respectively connected to an output of the pulse-generating circuit. The first and second delay circuits are of the integrating type having capacitances which are charged over time. The second delay circuit is a reference circuit and has a delay based on a fixed capacitance. The first delay circuit has its capacitance based on a capacitance of a detection electrode. The first and second delay circuits each have their respective capacitances charged or drained by constant current circuits, each moving the same amount of current. Outputs of the first and second delay circuits are each applied to a respective limiting amplifier such as a Schmitt trigger, each Schmitt trigger then has an output to input to a common phase detector. The phase detector determines the sequence of arrival of pulses generated by the first and second delay circuits.Type: GrantFiled: June 7, 1995Date of Patent: September 10, 1996Assignee: Seikosha Co., Ltd.Inventors: Kazunori Kawashima, Hajime Oda, Takahiro Miyajima
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Patent number: 5542118Abstract: A remote, unpowered passive transmitter has a tank circuit, a coil and capacitor. The capacitor is variable to vary the frequency of the tank. This is coupled to a receiver having a hybrid splitter. With four ports, two balanced, opposing ports connect to two lines terminating in line impedance. The tank couples into one of the two line so that a difference signal is formed and output. Line loading forms a signal indicating tank frequency.Type: GrantFiled: September 13, 1994Date of Patent: July 30, 1996Inventor: Thomas J. Warnagiris
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Patent number: 5517176Abstract: An exit bar has an elongated body for mounting on an exit door. The exit bar incorporates a pair of independent sensors. An infrared beam is generated along the front of the bar. An infrared detector produces a first signal when the beam is interrupted. The first signal results in release of a lock securing the door. If the beam is interrupted for longer than a pre-set time limit, a first alarm sounds. A capacitance sensor produces a second signal when the sensor detects changes of capacitance in the bar as a result of contact or near contact with foreign objects. The second signal also results in release of the lock securing the door. If the capacitance sensor detects a capacitance change for longer than a pre-set time limit, a second alarm sounds.Type: GrantFiled: February 6, 1995Date of Patent: May 14, 1996Assignee: Harrow Products, Inc.Inventors: Gary E. Lavelle, George Frolov, George A. Baehr
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Patent number: 5467022Abstract: A dielectric detecting system comprises: an earth electrode; a sensor electrode opposed to the earth electrode for constituting a first condenser therebetween whose electric capacitance varies in dependence on an existence of the dielectric; a medium electrode positioned between the earth electrode and the sensor electrode for constituting a second condenser between the medium electrode and the earth electrode and a third condenser between the medium electrode and the sensor electrode in such a manner that one of an electric capacitance of the second condenser and an electric capacitance of the third condenser serves for detecting an other dielectric; and an operational amplifier for equalizing electric potential of the medium electrode to that of the sensor electrode.Type: GrantFiled: January 15, 1993Date of Patent: November 14, 1995Assignee: Aisin Seiki Kabushiki KaishaInventors: Kouji Aoki, Masaru Yokochi
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Patent number: 5446444Abstract: A test circuit for testing operation of a liquid level detector. The liquid level detector includes a probe that is placed at a test site. A control circuit monitors changes in capacitance of the probe due to changes in the liquid level at the test site. A test switch grounds an input to the probe which and causes the control circuit to sense an alarm condition. If the detector does not activate an alarm when the test switch is actuated, the detector is not properly functioning and repair or replacement of the level detector is needed.Type: GrantFiled: December 17, 1993Date of Patent: August 29, 1995Assignee: Robertshaw Controls CompanyInventor: Benjamin N. Lease
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Patent number: 5446391Abstract: A dielectric detecting device includes an earth electrode and a sensor electrode opposed to the earth electrode which constitute a capacitor whose capacitance is varied with an existence of a dielectric object therebetween. A detecting device is provided for detecting a change in the capacitance of the capacitor and a capacitance of a circuit in the dielectric detecting device. The detecting device includes an input signal processing device disposed between an output side of the detecting device and an input side of the sensor electrode, a switching device disposed between the input signal processing device and the sensor electrode, and a judging device for judging whether the dielectric object exists or not on the basis of an output of the detecting device and judging whether an error has occurred at one or more of the earth electrode, the sensor electrode, the detecting device and input signal processing device on the basis of capacitances when the switching device is in its on and off conditions.Type: GrantFiled: April 21, 1993Date of Patent: August 29, 1995Assignee: Aisin Seiki Kabushiki KaishaInventors: Kouji Aoki, Masanori Sugiyama, Koichi Sugiyama
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Patent number: 5442347Abstract: A capacity type proximity sensor comprised of a capacitance type sensor, a capacitance type reference, and two independent and mutually opposing driven shields respectively adjacent the sensor and reference and which are coupled in an electrical bridge circuit configuration and driven by a single frequency crystal controlled oscillator. The bridge circuit additionally includes a pair of fixed electrical impedance elements which form adjacent arms of the bridge and which comprise either a pair of precision resistances or capacitors. Detection of bridge unbalance provides an indication of the mutual proximity between an object and the sensor. Drift compensation is also utilized to improve performance and thus increase sensor range and sensitivity.Type: GrantFiled: January 25, 1993Date of Patent: August 15, 1995Assignee: The United States of America as represented by the Administrater, national Aeronautics & Space AdministrationInventor: John M. Vranish
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Patent number: 5440291Abstract: The invention is a system for detecting the presence of an intruder in a passageway. In detail, the system includes at least one capacitance probe for mounting on the wall of the passageway, the probe including a sensing member in the form of a rod extending into the passageway, the number, spacing and length of the sensing members sufficient to detect an intruder attempting to pass through the passageway.Type: GrantFiled: July 1, 1993Date of Patent: August 8, 1995Assignee: Lockheed CorporationInventors: Melvin P. Foster, Jr., James M. Woodward
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Patent number: 5380983Abstract: An electrical appliance, such as a pressing iron (10), includes a user proximity sensor for removing electrical power from the appliance after a period of non-use. When a user's hand is in close proximity to, or is in a grasping relationship with, a handle (28) of the pressing iron, an antenna (44) that is disposed within the handle is capacitively coupled to the user through a dielectric material that forms the handle wall. When so coupled to the user, a displacement current having a frequency equal to the AC line electrical power frequency signal (50 Hz or 60 Hz) is capacitively coupled between the user's body and the antenna. The displacement current is detected and amplified by circuitry (60) that is connected to the antenna by a conductor (46). This circuitry outputs a signal that indicates the proximity of the user to the handle of the pressing iron. The output signal is in turn employed to disable the operation of a time-out circuit (70).Type: GrantFiled: July 12, 1993Date of Patent: January 10, 1995Assignee: Black & Decker Inc.Inventors: Luis O. Cavada, Joseph Carley, Leonard I. Horey, Peter R. Hohlfeld
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Patent number: 5337353Abstract: Capacitive proximity sensors are disclosed that can be fabricated in different shapes, sizes and materials used in a wide variety of applications. Each such sensor includes a sensing electrode and a guard electrode. The sensor electrode and guard electrode can be parallel conductors separated by an insulating layer, such as a double-sided circuit board shaped to suit the application. One such sensor is transparent for use in conjunction with an optical bar-code scanner. Another sensor is annular in shape for use in conjunction with a telephone transmitter. The sensing electrode and the guard electrode are driven in unison by an RF signal. The proximity of an object to the sensor is observed by detecting changes in the RF current flowing through the sensing electrode caused by the proximity of an object to the sensing electrode.Type: GrantFiled: April 1, 1992Date of Patent: August 9, 1994Assignee: AT&T Bell LaboratoriesInventors: Robert A. Boie, Gabriel L. Miller
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Patent number: 5337039Abstract: An oscillator which produces a continuous wave output signal on an antenna having a preset frequency. A detection circuit detects changes in the preset frequency resulting from proximity between the antenna and an object and when such an object is detected, the detection circuit generates an output signal. A compensation circuit is also provided for compensating for changes of the preset frequency which are caused by factors other than proximity of the antenna with an object. Such other factors include radio frequency interference, long term component degradation, temperature, and the like.Type: GrantFiled: July 16, 1992Date of Patent: August 9, 1994Assignee: SDR Metro Inc.Inventor: Arvin B. Simon
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Patent number: 5313190Abstract: A motor vehicle sensing and warning circuit is described that includes a series of N Schmitt triggers with MOS P-channel and N-channel enhancement devices included in a single monolithic structure to perform waveform generation, sensing, comparison and control functions. The Schmitt triggers are configured to deliver as an astable oscillator in circuit with a sensing antenna through a balance circuit as well as deliver as an audio oscillator to drive a piezo element to alert the driver of the presence of an invading object that should be avoided. Shaping and conditioning of the reference waveform are generated by the free running oscillator, as is a comparison function in association with a series of strobing diodes resulting in a strobed output summing function between a Schmitt sensing trigger and a Schmitt reference trigger associated with the free running oscillator.Type: GrantFiled: June 5, 1992Date of Patent: May 17, 1994Inventors: Ruben E. Clayton, John M. Mueller
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Patent number: 5247281Abstract: This detector comprises a variable radio frequency oscillator (1) producing a first electrical signal, a transmission circuit (3) with a capacitive antenna to which said first signal is applied, a reception circuit (6) forming, with the transmission circuit (3), a selective coupler for picking up a second electrical signal at the frequency of the oscillator, and a circuit (9) for comparing the phases of the first and second electrical signals and producing an output signal in response to a variation of the phase shift between said signals due to the presence in the surroundings of the antenna of a foreign body to be detected.The detector further comprises a feedback circuit (13) driven by the output signal of the comparison circuit (9) and controlling the oscillator (1) in order to make the frequency of the first signal vary in the sense which tends to cancel out said variation of the phase shift.Type: GrantFiled: July 7, 1992Date of Patent: September 21, 1993Assignee: Societe anonyme dite Bertin & CieInventors: Pierre Facon, Pierre Sajot
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Patent number: 5235217Abstract: In a preferred embodiment, a capacitive switch system including two capacitive switches which must be activated nearly simultaneously to operate a piece of equipment. When one switch is touched, a timing function is activated. If a predetermined length of time lapses before the other switch is touched, the other switch will be locked out. Both switches must then be released before the activation procedure is re-initiated. The components providing timed and anti-tie-down features, are integral to the circuitry of the switches and these as well as output relays are compactly housed in the switch housings to prevent tampering and circumvention of the safety features. The sensitivity of the switches is such that they cannot be activated by liquids.Type: GrantFiled: July 24, 1991Date of Patent: August 10, 1993Assignee: ISB Ltd.Inventor: James Kirton
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Patent number: 5223817Abstract: An intruder detector system such as a microwave fence having a transmitter 10 and receiver 12 produces a signal proportional to the disturbance created by an intruder. The signal is processed by a microwave detector 14 and processor 16 and supplied, as DC voltage output to two channels 18, 20. First channel 18 compares the DC voltage strength to a pre-set value stored in a first threshold detector/comparator 22. On the DC voltage exceeding the pre-set value an alarm relay 24 is actuated causing actuation of an alarm (not shown). Second channel 20 passes the voltage through a first filter 26 which removes high frequency signal variations characteristic of a fast moving intruder. Thus the signal which is compared with a second pre-set value stored in a second threshold detector/comparator 28 relates only to slow moving intruders and the preset value can therefore be set for a lower level of disturbance as would be caused by a crawling human intruder.Type: GrantFiled: September 13, 1991Date of Patent: June 29, 1993Assignee: Shorrock LimitedInventor: Roger W. L. Hoyle
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Patent number: 5166679Abstract: A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.Type: GrantFiled: June 6, 1991Date of Patent: November 24, 1992Assignee: The United States of America as represented by the Administrator of the National Aeronautics & Space AdministrationInventors: John M. Vranish, Robert L. McConnell
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Patent number: 5164706Abstract: An alarm device connectable to a handbag or brief case includes a sensor built into an attachment strap that connects the housing of the device to the handbag or brief case. The alarm device also includes an electronic circuit that includes a continuous, high frequency oscillator that has a bypass capacitor connected in parallel to the sensor. A sound circuit is connected to the oscillator by the gate of a transistor and is normally reversed biased thereby. The sound circuit includes a dual oscillation circuit, an amplifier, and a speaker. When a human being or other creature approaches the sensor too closely, it creates an additional capacitance that is added to the capacitance of the bypass capacitor with the result that the oscillator stops oscillating, removing the reverse bias applied to the gate of the transistor. The speaker then emits a sound generated by the dual oscillation circuit.Type: GrantFiled: September 11, 1991Date of Patent: November 17, 1992Inventor: Yoky Chen
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Patent number: 5150038Abstract: A detector for detecting an extraordinary approach of objects having earth potential toward a power transmission line comprises a charging current detection circuit for measuring variations in a charging flowing from the power transmission line into a stray capacitance formed between a detector casing and the earth and a transmitter for sending the value measured by the charging current detection circuit to a receiver installed outside the detector casing by wireless means or a wire. The detector is always able to monitor the extraordinary approach of objects such as trees toward the power transmission line, thereby preventing in advance the accidental grounding of the line.Type: GrantFiled: July 30, 1991Date of Patent: September 22, 1992Assignee: Hitachi Cable LimitedInventors: Kimiharu Kanemaru, Junichi Kaitou
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Patent number: 5148149Abstract: An electromagnetic intrusion sensor including a sensing element, a first phase shifter circuit for phase shifting an input or oscillation signal in accordance with a capacitance of the sensing element, a second phase shifter circuit for outputting a reference signal having a fixed delay relative to the input or oscillation signal, a phase detector circuit for providing a detector signal having a duty cycle representing the phase differential between the outputs of the first and second phase shifter circuits, and an oscillator circuit for outputting a signal having a frequency which changes according to the duty cycle of the detector signal.Type: GrantFiled: January 31, 1991Date of Patent: September 15, 1992Assignee: Allied Security Devices, Inc.Inventors: David J. Campbell, Kenneth I. DeWitt
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Patent number: 5130672Abstract: A sensor, especially for detecting misfeeds in a stream of sheets of paper, comprises a pair of sensing plates sensing changes in the capacitance between the plates, a first oscillator providing an output signal at a frequency representative of the capacitance, a second oscillator set to a reference frequency which is the same as or close to that frequency generated by the first oscillator when no object is between the sensing plates, gating means to produce an output representative of the frequency difference between the oscillator outputs, a low-pass filter, and a microprocessor which responds to changes in the difference frequency.Type: GrantFiled: September 19, 1990Date of Patent: July 14, 1992Assignee: Watkiss Automation LimitedInventors: Michael C. Watkiss, Allan G. Coaker
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Patent number: 5081406Abstract: A method and system and associated circuitry for controlling and stopping the motion of dangerous moving parts such as power saw blades substantially instantaneously in response to body or human capacitance produced by an operator coming with a predetermined critical distance from the moving part. This method includes, and this system provides for, among other things, connecting an antenna to the moving part and then coupling a tunable circuit to the antenna so that the antenna provides a variable lumped capacitance parameter (dependent upon human body capacitance) within the tunable circuit. This lumped capacitance parameter is variable in response to body or human capacitance produced when an operator comes within a predetermined critical proximity to the moving part.Type: GrantFiled: June 26, 1990Date of Patent: January 14, 1992Assignee: Saf-T-Margin, Inc.Inventors: Rickey D. Hughes, James T. Reese
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Patent number: 5068642Abstract: Alarm or warning device using, as sensing means, a low voltage D.C. biased shielded coaxial cable. The cable is positioned along the periphery of the area under control, and one or both of its ends are connected to an electronic circuit adapted to detect the voltage variations at the cable ends, deriving from its capacity variations resulting from the subsonic shock waves caused by the movement of things or people in the neighborhood of the cable. The device of the invention is used in alarm systems against intrusions and thefts, both for real and personal property. In the first case, it is preferably positioned underground and it may also comprise screening means allowing to detect the movements coming from different directions. The device is also advantageously used in the medical field, for the remote control and warning of the life functions of a patient.Type: GrantFiled: March 29, 1990Date of Patent: November 26, 1991Assignee: Hesa S.p.A.Inventors: Vincenzo Hruby, Raffaele Vizzotto
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Patent number: 5034722Abstract: A capacitance sensing security system in which comparison/reference and sensing oscillator are coupled together to operate in substantial frequency synchronism, each of the oscillators includes an amplifier having input and output terminals and a feedback circuit including a capacitor connected to the input terminals, the feedback circuit connected to the sensing oscillator exhibiting a low capacitive reactance, the input terminals of the sensing oscillator being connected to one or more objects to be secured so that extraneous transient signals appearing at or on the objects do not affect the phase/frequency of the sensing oscillator, the resistive component being substantially greater than the resistance of the input terminals and is provided either by adjusting the value of the capacitive component in the feedback circuit and/or disposing a resistor in series therewith.Type: GrantFiled: January 16, 1990Date of Patent: July 23, 1991Inventor: Joshua Premack
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Patent number: 5019804Abstract: A sensor electrode is capacitively coupled to the environment. Electric charges carried by surrounding objects induce corresponding electric charges on the sensor electrode. A high input impedance circuit senses change in charge on the electrode and provides a first varying signal indicative of that change. A second circuit compares the first signal against a threshold level and provides a second signal indicative of the movement. A pair of sensors may be included to cancel out extraneous environmental chasrges. Difference between charges on each sensor electrode of the pair is compared in a circuit which provides signal indicative of the difference. The varying signal is compared against a threshold to provide a signal indicative of the movement.Type: GrantFiled: April 10, 1989Date of Patent: May 28, 1991Inventor: Jacob Fraden
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Patent number: 4922227Abstract: A touch-controlled switch and alarm system for protecting electrically conductive objects. The touch switch automatically adjusts itself within a few seconds to a wide range of ungrounded conductive objects, is not triggered by AC power line transients or failures, has a back-up battery for operation during power failures, and is automatically triggered if the power plug is disconnected. A unique underdamped automatic gain control circuit allows a simple unidirectional trigger to sense both increases and decreases of capacitance to ground. The alarm includes a lock switch for arming and disarming the alarm, and status indicators to show whether or not the system has been armed or triggered. The lock switch itself is protected by the alarm system because the lock switch has an electrically conductive body which is connected to the touch switch along with the protected objects.Type: GrantFiled: January 24, 1989Date of Patent: May 1, 1990Inventor: Bryce L. Hesterman
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Patent number: 4891627Abstract: A device for detecting an object includes apparatus for converting a variation of a floating capacity between a sensor consisting of an electrode plate and an object to be detected into a variation of a frequency signal and apparatus for detecting the state of approach of the object in accordance with the attenuation of the frequency signal.Type: GrantFiled: May 9, 1989Date of Patent: January 2, 1990Assignee: Honda Giken Kogyo Kabushiki KaishaInventor: Eiji Murao
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Patent number: 4887066Abstract: The capacitive proximity sensor for motor vehicles comprises a capacitance-measuring device for measuring the capacitance between at least one capacitor plate (1) which is fixed to the motor vehicle, on the one hand, and the environment, on the other hand, and an indicator for receiving the output signal of the measuring device.To provide a proximity sensor in which the disturbing and parasitary capacitances occurring in practice are particularly taken into account, the output signal S.sub.c of the capacitance-measuring device (5) is delivered to an amplifier (6), which is provided with a degenerative feedback loop (9) comprising a storage device (11) and a switch (10) so that the output signal (s.sub.A) of the amplifier (6) is held constant during normal travel, and the switch (10) is opened to interrupt the degenerative feedback loop (9) for a measurement. The switch is closed when the measurement has been completed.Type: GrantFiled: June 11, 1987Date of Patent: December 12, 1989Assignee: Setec Messgerate Gesellschaft m.b.H.Inventor: Jiri Marek
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Patent number: 4887024Abstract: A person detecting device detects the presence and absence of a person in a certain space such as a vehicle compartment. The device includes means for sensing the capacitance between a pair of electrodes with a space where a person may present, oscillating means for providing a first pulse signal and means for delaying the first pulse signal and providing a second pulse signal delayed in response to the capacitance. The device further includes means for receiving the first and second pulse signals and providing a third pulse signal of a duty ratio determined in response to the capacitance. The third pulse signal is further converted to a value representing the duty ratio which is compared with at least a reference value preset for judging as to the presence and absence of the person.Type: GrantFiled: October 27, 1988Date of Patent: December 12, 1989Assignees: Aisin Seiki Kabushiki Kaisha, Toyota Jidosha Kabushiki KaishaInventors: Masanori Sugiyama, Takayoshi Masutani, Takao Shirai
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Patent number: 4884061Abstract: An apparatus for verifying the integrity of a wall automatically sets off an intervention in the case of an act committed against the wall. A capacitive sensor is formed on the external or internal surface of the wall and consists of a thin planar condenser matching the shape of the wall. An oscillator having variable frequency has its control input connected to a plate of the condenser, the other plate being connected to ground, and a circuit detects the variation of frequency of the output signal of the oscillator resulting from a variation of condenser capacitance.Type: GrantFiled: May 26, 1988Date of Patent: November 28, 1989Assignee: Axytel S.A.Inventor: Christophe Genevois
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Patent number: 4831279Abstract: A capacitive detecting circuit for detecting transient capacitive changes such as that of a person moving into proximity of a sensing element. A sensing element is coupled to a threshold level controlled amplifier supplied with relatively high frequency signals from an oscillator through a high input impedance. A detector circuit is coupled to the amplifier output to detect D.C. variations in the level control loop caused by transient capacitive changes and provide a control output signal representative of such change.Type: GrantFiled: January 27, 1988Date of Patent: May 16, 1989Assignee: Nartron CorporationInventor: Ronald D. Ingraham
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Patent number: 4804945Abstract: An alarm system for providing separate discrete signals corresponding with the approach of an individual to a door and the touching of the door knob by the individual utilizes a combination of infrared sensors and a capacitive discharge sensor. The infrared sensors are mounted on a circular ring on the face of the door knob. The sensors are angled in different directions to detect individuals approaching from various directions. The door knob is composed of a metallic material and acts as an antenna of a capacitive discharge proximity sensor. The door knob is insulated by a sleeve from the rest of the door and latch structure. Approach of an individual is detected by the infrared sensors which activates a first alarm signal. When the individual reaches for and touches the door knob, a second different alarm is activated.Type: GrantFiled: October 29, 1987Date of Patent: February 14, 1989Inventor: Terrance Millet
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Patent number: 4796013Abstract: A capacitive occupancy detector apparatus includes a personnel containment device having first and second electrodes which will define an electric field therebetween which will be intercepted by a person present in the containment device. A detecting device is provided for detecting the capacitance formed between the first and second electrodes and a processor is provided for storing the capacitance at predetermined periods. The difference between the last capacitance detected and a capacitance previously stored is detected to determine the presence of a person when the difference indicates an increase of the capacitance exceeding a first predetermined threshold. A second threshold is set based upon the capacitance which determines the presence of a person so that the subsequent determination of the absence of a person is based upon detecting a decrease of the capacitance with respect to the second threshold.Type: GrantFiled: October 15, 1986Date of Patent: January 3, 1989Assignee: Aisin Seiki Kabushiki KaishaInventors: Tomio Yasuda, Jun Sato, Masao Ohashi
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Patent number: 4743902Abstract: A system for measuring the relative movement of one object with respect to another, such as the movement of a slide with respect to a scale of a measuring instrument utilizes the capacitative effect of a series of electrodes associated with a slide and another series of electrodes associated with the cooperating scale, the changes in capacity caused by relative movement between the two members being analyzed by an electronic circuit.Type: GrantFiled: December 12, 1986Date of Patent: May 10, 1988Assignee: Stiftelsen Institutet for Mikrovagsteknik vid Tekniska HogskolanInventor: Nils I. Andermo
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Patent number: 4742549Abstract: A procedure for watching over the area in front of a lift door, of said area being formed with the aid of one-dimensionally or two-dimensionally grouped photoelectric image point pick-ups, image signals suitable to be digitally processed, with a pick-up signal preprocessing means based on mutual interaction of the image points.Type: GrantFiled: October 4, 1985Date of Patent: May 3, 1988Assignee: Elevator GmbHInventor: Nils-Robert Roschier
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Patent number: 4710751Abstract: A sensor circuit for detecting a ground fault in devices that eliminate or prevent static electricity and for producing appropriate alarm signals to indicate an undesirable ungrounded condition. In particular, the sensor circuit includes means for monitoring a ground-fault system by using a wrist strap monitoring circuit, a proximity monitoring circuit and at least one surface monitoring circuit. The wrist strap monitoring circuit and the surface monitoring circuits are used to detect the status of a grounding connection between an operator and/or a surface at a work station and a ground potential. The proximity monitoring circuit is used to determine whether an operator (or another person) is in proximity to the work station. A logic circuit means detects the status of the aforementioned monitoring circuits and selectively activates an alarm means if a fault condition exists.Type: GrantFiled: April 24, 1986Date of Patent: December 1, 1987Assignee: Environmental Protection SystemsInventor: James B. Webster
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Patent number: 4689492Abstract: A switching circuit for turning on and off an electronic instrument, an electric lamp, or other electrically powered electric or electronic circuits, by means of a single switch, and which is constructed so that when the switch is closed momentarily and opened, the switching circuit remains "on" until the switch is again momentarily operated. However, when the switch is closed for a longer time interval, the switching circuit remains "on" for so long as the switch is closed and turns "off" when the switch is opened.Type: GrantFiled: August 1, 1986Date of Patent: August 25, 1987Inventor: Donald D. Peteuil
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Patent number: 4684931Abstract: Separate signal input circuits respond to intruder disturbances of a capacitive wire sensing grid to generate signal outputs processed to reject signals caused by environmental phenomena with a high degree of statistical probability, by comparison of individual signal outputs with an averaged signal output from all of the signal input circuits.Type: GrantFiled: May 14, 1985Date of Patent: August 4, 1987Inventor: Sydney Parks
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Patent number: 4679032Abstract: A procedure and an apparatus for producing an image based on contrast discrimination in an image forming apparatus with one-dimensional or multidimensional image field.Type: GrantFiled: December 5, 1984Date of Patent: July 7, 1987Assignee: Elevator GmbHInventor: Nils-Robert Roschier