Abstract: In an occupant detecting apparatus for detecting an occupant seated on a passenger seat of a vehicle with an airbag for the occupant, a load sensor is provided in a bottom part of the seat. A plurality of first electric field sensors are provided in the bottom part of the seat, and a plurality of second electric field sensors are provided in a rear part of the seat. An airbag inflating permission control unit permits inflation of the airbag in accordance with output signals of the load sensor and the first and second electric field sensors.

Abstract: 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 a locator device. A human operator holds the device in hand to thereby electrically and dielectrically connect the device 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 nearly horizontal state, and the operator scans the device in a constant speed uniform linear motion back and forth. An antenna extends from the front of the device, and both are acted on by the dielectrophoretic force.

Abstract: A system and method for detecting user entry into a defined danger zone surrounding a saw blade includes a non-conducting member defining an opening therein for receiving a saw blade. The non-conducting member may comprise, for example, an insert received by an opening in the work surface or table of a table saw, scroll saw, band saw, miter saw, etc. Alternatively, it may comprise the blade guard of a radial arm saw or miter saw, for example. A conductive sensor is situated on the non-conducting member adjacent the opening to define a danger zone near the saw blade. A voltage source is coupled to the sensor, and a monitor circuit is configured to detect a change in the sensor's capacitance so as to signal a user entry into the danger zone.

Abstract: The dielectrophoretic force caused by the non-uniform electric field squared spatial gradient three-dimensional pattern uniquely exhibited by a predetermined type of inanimate entity can be detected by a locator device. A human operator holds the device in hand to thereby electrically and dielectrically connect the device 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 nearly horizontal state, and the operator scans the device in a constant speed uniform linear motion back and forth. An antenna extends from the front of the device, and both are acted on by the dielectrophoretic force.

Abstract: A proximity switch is described, specifically a capacitive proximity switch, with two signal transmitters (1, 2) and with one signal receiver (3), a first signal output (4, 5) of each of the two signal transmitters (1, 2) being connected to one another and to a first signal input (6) of the signal receiver (3), and a second signal output (7, 8) of each of the two signal transmitters (1, 2) being connected via a respective signal transmission path (9, 10) to a second signal input (11) of the signal receiver (3), and at least one of the two signal transmission paths (9, 10) can be influenceable by an actuating object.

Abstract: A seat-occupant sensing device for a car seat is provided, such that a heater can be installed in the seat without deterioration of sitting comfort. A load sensor is mounted to a cushion frame of a car seat. The end of a flexible cushion support is linked with the load sensor. Because the flexible cushion support flexes when a person sits on the seat, the load sensor detects the moment when the person sits on the seat.

Abstract: The invention is directed to improved automatic dispenser apparatus for dispensing sheet material and the like without contact between a user and the dispenser. Proximity detection apparatus is provided to detect the presence of a user in a detection zone generated outside the dispenser. Control apparatus controls actuation of the dispenser in response to the detected user. Preferred forms of the proximity detector include a sensor and a signal detection circuit operatively connected to the sensor. The sensor includes conductors configured to have a capacitance and positioned such that the capacitance is changed by the presence of a user within the detection zone. The signal detection circuit detects the change in capacitance and is provided with an oscillator having a frequency which is affected by the sensor capacitance and a differential frequency discriminator which detects changes in the oscillator frequency.

Abstract: A fingerprint identification device judges that the input fingerprint is identical to the fingerprint in the database only when a the touch sensor detects the human finger and a the fingerprint processing unit detects that the input fingerprint is identical to a fingerprint in the database. The touch sensor includes an oscillator that outputs a high frequency signal. An electrode unit applies the high frequency signal to the human finger. A detector unit detects a variation of impedance values varied by the human finger contracting the electrode unit and outputs an output signal based on the variation of impedance values. A discriminator unit determines whether the human finger is in contact with the electrode unit by comparing the output signal from the detector unit with a predetermined reference value.

Abstract: Physical structures respond to proximity or touch, conveying to a reader information such as the identity of the structure or some data associated therewith. In its simplest form, the structure comprises an electrical load and a pair of electrodes connected thereto. The electrodes are spaced apart (by air or other dielectric medium). A signal generator, which acts as a “reader,” is connected to a larger electrode that may be embedded in an environmental surface. When the structure is placed in proximity to the reader electrode, application of the signal results in capacitive coupling between the reader and the electrodes of the structure. The structure is not detected by the reader, however, because the capacitive coupling is comparable for both electrodes, so the load experiences only a small electrical gradient. But if one of the electrodes is grounded, this symmetry is broken and current is drawn through the load.

Abstract: A method and apparatus for capacitively sensing one or more pests is disclosed. The detector may be employed as either a passive detector and/or as a part of a combined detector and trap. The sensor system includes at least two sensor electrodes and a capacitance sensing circuit. When a non-capacitive object, such as a pest, approaches the sensor electrodes, the capacitance of the sensor electrodes increases due to the object having a higher dielectric constant than air. A capacitance sensing circuit detects the increased capacitance and provides an output signal that a pest has entered the area being monitored. The capacitance sensing circuit may also be constructed to measure the change in the electrode in order to determine the size and/or type of pest based on a characteristic change.

Abstract: A human body detecting device for detecting an approach of a human body includes a sensor electrode provided in a housing and having detecting portions for detecting the approach of the human body to the housing. The detecting portions of the sensor electrode detect at least two different surfaces of the housing, and each of the detecting portions is provided at each surface side in the housing.

Abstract: In a process for capacitive object detection in a vehicle seat, capacitors arranged in the backrest and in the seat surface are influenced by an object. The capacitors are acted upon by alternating voltage, and the time variation of their capacitances is determined individually. From the values of each of the two capacitances, an evaluation of the object is derived by means of a value table and, when the two evaluations correspond to one another concerning the type of an object, an occupant protection system assigned to the seat is correspondingly activated.

Abstract: A passenger detection system is provided. The passenger detection system utilizes an oscillation circuit that causes an antenna electrode to emit an electric field that is disrupted by the electrical characteristics of an object placed on the seat. This disruption alters the current and phase of the signal in the antenna electrode. By comparing the current flowing in the antenna electrode and/or the difference between the phase of the signal in the antenna electrode and the oscillation circuit output signal with predetermined threshold values, it is possible to detect the presence of a passenger in a reliable and inexpensive manner. Environmental sensors are used to make the determination more accurate. Humidity, moisture and/or grounding condition are detected and used to alter processing, values or calculations.

Abstract: A vehicle occupant proximity sensor includes a transmitting electrode in a vehicle seat and an array of receiving electrodes mounted in a vehicle headliner above the vehicle seat. The sensor determines the capacitance at each of the receiving electrodes, which varies based upon the proximity of the occupant to each receiving electrode, thus producing an array of proximity information indicating in two dimensions the position of the occupant.

Abstract: A non-contact obstacle detection system utilizing ultra sensitive capacitive techniques. In an exemplary embodiment, the system includes a sensing element disposed in proximity to a moveable panel and a proximity detection circuit in communication with the sensing element. The proximity detection circuit generates a differential output signal reflective of whether a foreign object is in proximity to the sensing element. In addition, a central control module is in communication with the sensing element. The central control module determines whether the differential output signal is reflective of a foreign object in proximity to the sensing element. If the central control module determines that the differential output signal is reflective of a foreign object in proximity to the sensing element, and the moveable panel is moving toward a closed position, then the central control module generates a control output signal to stop the moveable panel from moving toward the closed position.

Abstract: A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object includes at least two sense electrodes disposed on a surface and a phase locked loop, including a voltage controlled oscillator and a phase/frequency comparator, connected between the sense electrodes and an RC network for providing an operating frequency to the sense electrodes. A circuit loop, including a reference oscillator, provides a fixed frequency reference for the phase locked loop to follow and a phase delay circuit connected between said phase/frequency comparator and said voltage controlled oscillator causes the voltage controlled oscillation to run ahead of the reference oscillator. A trigger circuit provides a control output in response to a change in phase shift between said fixed frequency and said operating frequency.

Abstract: A method for operating an electronic device. The method includes receiving an electrical signal from a sensor attached to the device and determining whether the device is being handled by a user based on the signal. The method includes switching the device from an inactive state to an active state in response to determining that the device is being handled.

Abstract: A sense electrode (12) is driven by a first oscillatory signal (26) and at least one control electrode (14) is driven by a second oscillatory signal (30). In first (38) and second (40) states (36), the second oscillatory signal (30) respectively has a first and second phase with respect to the first oscillatory signal (26). The proximity of an electric-field-influencing media (20) to the proximity sensor (10) is responsive to the difference of third (50) and fourth (52) signals that are respectively measured when the second oscillatory signal (30) is in respective first (38) and second (40) states. The proximity sensor (10) is calibrated with a known capacitance operatively coupled to the sense electrode (12) with a plurality of switches (S1, S2) adapted so that the switches (S1, S2) have a relatively small effect on the capacitance of the sense electrode (12).

Abstract: In a method for capacitive object recognition in vehicles, two capacitive electrodes are charged with alternating voltage and the presence of an object is detected by the change in the capacitance in the capacitor. The two electrodes are charged sequentially and individually with alternating voltages. The alternating currents that result in the leads of the two electrodes are analyzed jointly.

Abstract: An electric field sensor (12) comprising at least one electrode (26) mountable within a seat (14) is operatively coupled to a sensing circuit (38), which applies an oscillating signal (28), comprising at least one frequency or at least one pulse, to at least one electrode (26) and generates a signal (32) responsive to at least one electric-field-influencing property of an object proximate to the electric field sensor (12). At least one frequency or pulse width of the applied signal (28) are adapted to be at most weakly responsive to a wetting condition of the seat (14).

Abstract: A sensor apparatus and a safety apparatus which can ensure significantly enhanced safety by monitoring constantly whether the sensor apparatus is operating normally. An auxiliary electrode plate of a small area is disposed in parallel and in opposition to an electrode plate with a short distance therefrom. A switching element is turned on every second for a period of milliseconds repetitively. When the switching element is turned on under the control of a central processing unit, the auxiliary electrode plate is connected to the ground potential, as a result of which a capacitance &Dgr;C effective between the auxiliary electrode plate and the electrode plate is electrically connected in parallel with a capacitor C0 effective between the electrode plate and a machine component, resulting in that the capacitance C0 is increased by a proportion corresponding to the capacitance &Dgr;C.

Abstract: A seat pressure sensor unit of the present invention is provided at a portion receiving a pressure of a seat. The sensor unit comprises a sensor provided on a top face of a base cloth and a heater wire provided on the top face of the base cloth not so as to overlap the sensor.

Abstract: In a human body detector, a wave-detection circuit for detecting waves of a resonance voltage is connected to a sensor resonance circuit that modifies a constant frequency voltage in accordance with a change in the capacitance of a sensor electrode. The wave-detection circuit is connected to a differentiator that acquires a changing rate by differentiating the wave-detection voltage with respect to time, and allows a voltage to pass if the changing rate of the voltage is greater than or equal to a predetermined value. The differentiator is connected to a high-pass filter that allows passage of a voltage whose changing rate is greater than or equal to a second predetermined value. The high-pass filter is connected to a comparator whose non-inversion input terminal is connected to a power source that applies thereto a reference voltage.

Abstract: A sense electrode (12) and a plurality of control electrodes (14) are located proximate to a region of space (18) for sensing an object (20) therein. A first signal (26) and a plurality of second signals (30) respectively applied to the sense (12) and control (14) electrodes generate an electric field (16) within the region of space (18). The capacitance of the sense electrode (12) is measured for various electric field configurations responsive to the second signals (30) and to the proximity of the object (20). A most likely proximity scenario from a priori proximity scenarios is determined from the plurality of capacitance measurements. A front driven shield (36) is provided between the sense electrode (12) and the region of space (18) for selectively shielding the sense electrode (12) from influence by objects (20) or grounds, so as to provide for calibrating the measurement circuit (32) to compensate for parasitic capacitance and gain drift.

Abstract: A moving object detecting apparatus, an abnormality alarm apparatus, and a load-carrying compartment opening control apparatus each have an oscillator circuit, an antenna, and a frequency fluctuation detector. If a moving object, such as a human or the like, exists near the antenna when a signal from the oscillator circuit is transmitted from the antenna, the load on the antenna fluctuates due to fluctuations in capacitance involved in the movement of the object. Due to the fluctuations in the antenna load, the oscillating frequency of the oscillator circuit fluctuates. The frequency fluctuations are detected by the frequency fluctuation detector.

Abstract: A capacitive object detection system for a vehicle has first and second capacitive electrodes embedded in the vehicle seat. The two electrodes are excited by oppositely phased alternating voltages, which are adjusted by a controller such that the resulting alternating currents in their respective feed lines are substantially equal and oppositely phased. The presence, size and location of an adjacent object is then determined based on an analysis of the impedances of the first and second electrodes.

Abstract: A passenger detection system is provided. The passenger detection system utilizes an oscillation circuit that causes an antenna electrode to emit an electric field that is disrupted by the electrical characteristics of an object placed on the seat. This disruption alters the current and phase of the signal in the antenna electrode. By comparing the current flowing in the antenna electrode and/or the difference between the phase of the signal in the antenna electrode and the oscillation circuit output signal with predetermined threshold values, it is possible to detect the presence of a passenger in a reliable and inexpensive manner. The determination is made with a two layer electrode arrangement, including smaller and larger electrodes. The two layers allow calculation of an amount of compression on the seat. The amount of compression is used to characterize the passenger.

Abstract: A passenger detection system is provided. The passenger detection system utilizes an oscillation circuit that causes an antenna electrode to emit an electric field that is disrupted by the electrical characteristics of an object placed on the seat. This disruption alters the current and phase of the signal in the antenna electrode. By comparing the current flowing in the antenna electrode and/or the difference between the phase of the signal in the antenna electrode and the oscillation circuit output signal with predetermined threshold values, it is possible to detect the presence of a passenger in a reliable and inexpensive manner.

Abstract: A bed includes a base, a support surface coupled to the base, and a controller configured to control at least one function. A control panel is coupled to the controller. At least one lockout switch is coupled to the controller.

Abstract: A brake light system is arranged to respond to movement within an r.f. field to provide a signal used to activate the brake light when movement within the r.f. field exceeds a predetermined velocity.

Abstract: An electric field sensor comprises at least one electrode mountable in a vehicle seat and a sensing circuit operatively coupled to the electrode, wherein the at least one electrode at least partially bounds at least one region that is proximate to an object such as an infant seat, a child seat, or a booster seat, for which the sensitivity of the sensor is preferably reduced. The at least one region without a conductive electrode may comprise a plurality of regions, and at least one of the regions may extend laterally across the seat. Furthermore, a plurality of electrodes may be incorporated, each having a different sensitivity to particular objects to be sensed, wherein an overall capacitance measurement that is dominated by the capacitance of the particular electrode that is most sensitive to the particular object can be used to indicate the presence of that object.

Abstract: The present invention is directed to a weight sensing apparatus (10) for a vehicle seat (22). The weight sensing apparatus (10) includes a differential capacitor (150) including a first capacitor (152) and a second capacitor (176). The first capacitor (152) includes first and second opposed plate assemblies (154 and 156). The second capacitor (179) includes a third plate assembly (180) and the second plate assembly (156). Each plate assembly (154, 156, and 180) includes a plurality of electrically conductive elongated members that extend in an axial direction. The second plate assembly (156) is interposed between the first and third plate assemblies (154 and 180) and is movable in an axial direction relative to the first and third plate assemblies (154 and 180) in response to a load being applied to a vehicle seat. A source of alternating current supplies electrical energy to the differential capacitor (150) and an output circuit is electrically connected with the differential capacitor (150).

Abstract: A passenger detection system comprises an antenna electrode, an oscillation circuit, a current detection circuit, a phase difference detection circuit, and a control circuit. The antenna electrode is placed on the upper side of a seat. The oscillation circuit generates a high frequency low voltage oscillation signal in order to generate a weak alternating electric field around the antenna electrode. The current detection circuit detects a transmission current which passes between the oscillation circuit and the antenna electrode according to the weak alternating electric field which is generated around the antenna electrode. The phase difference detection circuit detects the phase difference between the oscillation signal supplied from the oscillation circuit and an output signal which is supplied to the antenna electrode.

Abstract: A system of sensors to prevent cheating at a casino gaming table, where the sensors are strategically positioned about a casino gaming table to monitor the movement about certain established areas on the gaming table during certain established times during the play of the game. The tripping of a sensor in response to the detection of unauthorized movement about a certain area of the table sends a signal to a monitoring system which in turn alerts the casino so that the casino may respond to the unauthorized movement accordingly. The system of sensors can be used with a wide variety of card-based or chip-based casino gaming tables.

Abstract: An occupant sensor system (40) has an array (42) of sensors (48.sub.I -48.sub.IV). Each of the sensors (48.sub.I -48.sub.IV) senses the presence of a body portion of an occupant (14) proximately located to the respective sensor and provides a signal (50) indicative of the presence. A controller (30) processes information derived from the signals (50) to characterize the type of the body portion.

Abstract: In a locking system, used for instance on a vehicle, a switch or sensor initiates the interrogation of a data storage medium via a control unit to check for access authorization. If access authorization is given, the control unit releases the locks of the locking system automatically. To improve user convenience regarding the system release, at least one capacitance sensor in at least one door grip is provided. At least one first electrode of the sensor is situated in the inner shell of the door grip and a second electrode is placed in the door area opposite the grip. By applying antipole voltage to both electrodes, an electrical field is generated between the two electrodes. When a hand, which acts as a dielectric, approaches the grip, a change in the cumulative dielectric state between the two electrodes occurs. Such a change is recognized by the capacitance sensor and transformed into an electric pulse which initiates in the electrical control unit interrogation of the data storage medium.

Abstract: A patient detection system including a plurality of sensors located adjacent the support surface and each sensor having an output signal variable in response to the change detected by the sensor. A processor monitors the output signals and provide an indication of change of position of the body relative to the support surface and to individually recalibrate each of the plurality of sensors. The automatic recalibration occurs upon sensing a substantial change due to an item being moved onto the surface. The processor may also sense changes in the support surface and recalibrate each of the sensors upon a detection of change in the support surface. The processor recalibrates all of the sensors for small changes existing for a pre-determined duration and for all large changes. The processor recalibrates all of the processors for a combination of changes in less than all of the sensors from the previous calibration for each sensor.

Abstract: Between a reference voltage point and the emitter or the source of a transistor of which the collector or the drain is connected to a power source and to which an signal is input at its base or its gate, DC current passing means for causing a current to flow from the emitter or the source to the reference voltage point and a capacitor connected to the reference voltage point at one end and charged with a voltage generated in the DC current passing means are provided. A detection output for the signal is obtained from the emitter or the source of the transistor, or the other end of the capacitor.

Abstract: A passenger detecting system is disclosed, that comprises a seat, a plurality of electrodes disposed at predetermined intervals on at least the front surface of the seat, an oscillating circuit for generating a weak electric field between at least one particular electrode (referred to as a first type electrode) of the electrodes and the other electrodes (referred to as second type electrodes), a current/voltage converting circuit for detecting displacement currents that flow corresponding to the weak electric field and for converting the displacement currents into respective voltages, a controlling circuit for detecting a seating pattern of an passenger or the like on the seat corresponding to output signals of the current/voltage converting circuit, and an air bag device for inflating an air bag in case of a collision.

Abstract: A method and a measuring system for detecting static electricity in a measuring object includes at least a sensor, a voltage meter, and a processor unit with a signal processing unit connected to the voltage meter. The sensor includes a sensing element arranged so that the electric field of the measuring object induces in the sensing element an electric signal which is proportional to the change in the electric charge of the measuring object. The sensor includes a detector including a capacitive circuit, such as a capacitor circuit, having an integrating effect on the measuring values which are read off by the voltage meter, connected between the sensing element and the voltage meter.

Abstract: A current detector and metering circuit is provided for a dielectrokinesis detecting device. This device is particularly useful in the areas of locating obscured entities, such as human beings, animals, materials, or controlled substances. A current detector is attached to an antenna and detects when subtle changes in the dielectrokinesis occurs within an detection environment. The present current detector automatically zeros itself to ambient electric field values and then has a heightened sensitivity for changes in that electrical field caused by changes in the dielectrokinesis. The present invention can be used for detection of hidden entities or substance, for motion detection, for medical diagnostic detection, and other uses.

Abstract: A non-contact capacitive proximity detector includes a sensing plate and detection circuitry electrically coupled to the sensing plate. The detection circuitry comprises an oscillator electrically connected to the sensing plate and signal conditioning circuitry electrically connected to the oscillator. The signal conditioning circuitry includes a coupling capacitor C.sub.1, an envelope demodulator, a first comparator, a delay circuit and a second comparator. When an object is within a predetermined proximity to the sensing plate, the capacitance of the capacitor constituted by the sensing plate and the proximal object is at a level which causes the oscillator to generator an oscillating signal having a sufficient magnitude. The oscillating signal generated by the oscillator is applied to the envelope demodulator by way of the coupling capacitor. The envelope demodulator generates an envelope of the oscillating signal and applies the envelope to he first comparator.

Abstract: A method and device for sensing the distance between a first object and a second object so as to activate or facilitate predetermined actions when the distance has attained a certain value. A person (1) (first object) holds a handle (2) of a power tool, the handle being connected to a function generator (6) for a signal in turn connected to a unit (7) for encoding or modulating the signal. A capacitance (C1) exists between the hand of a person (1) and the handle (2). A capacitance (C2) exists between the person (1) and the active portion (4) (second object) of the tool connected to a demodulator or tone decoder (8) in turn connected to a control unit (9) incorporating the control circuitry. The control unit (9) controls the security system (10) in turn controlling the protective measures such as braking or power cut-off (11). The control unit (9) also controls an alarm and self-testing circuitry (11a).

Abstract: A dielectrokinesis detector includes a chamber housing an exact dielectric replicate reference material that is subjected to external static electrification. The reference material is mechanically constrained, enabling the detection of the polarization energy dynamics of constrained dielectrophoretic force indicating the presence of any target with dielectric properties identical to the properties of the reference material. An antenna assembly increases the proximity distance (range) of detection. The static electrification source for the reference material increases the longevity of the detection ability to provide continuous detection capability, and an external electronic circuit source of electrical energy via an electrical current surge gives a quantifiable manifestation of the detection.

Abstract: A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is of the sensor. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt's configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator.

Abstract: A system of sensors to prevent cheating at a casino gaming table, where the sensors are strategically positioned about a casino gaming table to monitor the movement about certain established areas on the gaming table during certain established times during the play of the game. The tripping of a sensor in response to the detection of unauthorized movement about a certain area of the table sends a signal to a monitoring system which in turn alerts the casino so that the casino may respond to the unauthorized movement accordingly. The system of sensors can be used with a wide variety of card-based or chip-based casino gaming tables.

Abstract: An apparatus for detecting the presence or absence of a patient adjacent to a patient-carrying surface of a patient-support device including at least one sensing element spaced apart from the patient-carrying surface, defining a detection space adjacent to the patient-carrying surface and providing an input signal in response to the dielectric constant within the detection space. A control unit provides an output signal indicating the presence or absence of the patient within the detection space in response to the input signal. A booster element including a plate positioned to lie adjacent the patient-carrying surface for shaping and positioning the detection space and a connector electrically coupling the plate to the sensing element may be provided.

Abstract: A roof-mounted passenger position sensor array of capacitive coupling passenger position sensors, to determine position and motion of a passenger by analysis of distances of the passenger to the various sensors of the array and analysis of the changes of said distances with time.

Abstract: The invention relates to a highly reliable mat sensor which can also detect temporary faults in a sensor portion. Two sensor portions are provided, and agreement or disagreement of an ON/OFF condition of the output from the two sensor portions is detected, and when the output conditions of the two sensor portions are in agreement, then a normal judgment signal for both sensor portions is generated. When the normal judgment signal is generated and the two sensor portions are OFF, an operation permit signal for a movable portion of a machine is generated. Moreover, the presence or absence of a body is detected from a change in value of the electrostatic capacity of one sensor portion. In this way, a temporary poor contact attributable to deterioration of the sensor portion can also be detected, and the movable portion of the machine can be stopped.

Abstract: 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.