Abstract: Provided is a battery pack producing method and a battery pack capable of suppressing defects such as overcharging or overdischarging in one or more of the used secondary batteries constituting a battery pack, and sufficiently exhibiting the performance of the used secondary batteries of the battery pack. This method includes an obtaining process for obtaining each full charge capacity of the used secondary batteries, a selecting process for selecting one or more used secondary batteries having similar full charge capacities from the used secondary batteries whose full charge capacities have been obtained, and an assembling process for assembling the selected secondary batteries.

Abstract: According to some embodiments, battery charge management using a scheduling application is disclosed. A first parameter may be received from a scheduling application running on a mobile computing device having a battery pack. Based on at least the first parameter and battery pack data, a required charge percentage for the battery pack may be determined and the remaining capacity of the battery pack may be determined. If the remaining capacity of the battery pack is less than the required charge percentage, a charge termination voltage may be determined and the battery pack may be charged to the charge termination voltage.

Abstract: A remotely controllable multiple battery system for reliably supplying electrical energy to an electrical system, the remotely controllable multiple battery system receiving control signals from a remote control device, the remotely controllable multiple battery system having a remotely controlled controller. An at least one sensor that senses the condition of a main battery and an at least one controlled switching device coupled remotely to the controller and responding to a signal from the remote control device to the controller thereby switching from the main battery to an at least one auxiliary battery.

Abstract: Measuring the voltage level of a mobile telephone battery during a charging operation involves disabling the charge temporarily so that the battery rapidly enters discharge mode. The discharge mode voltage is more representative of the true battery charge level, so that the present invention can be implemented to provide a battery charge level display that is accurate even when the telephone is being charged.

Abstract: A battery module for use in an electric vehicle is disclosed. The battery module includes a plurality of cells arranged in a predetermined pattern within the module. The battery module also includes an optical pyrometer arranged inside the module. The optical pyrometer is installed within the module after being tuned to detect a predetermined frequency or band of frequencies. The pyrometer will be used to detect an increase in short wave radiation density from one of the battery cells within the module wherein that battery cell has a temperature above a predetermined threshold. The optical pyrometer will be used to communicate an electric signal to a control system of the electric vehicle wherein that control system will implement a predetermined mitigation process to contain the thermal event of that one cell within the battery module.

Abstract: Disclosed herein is an electronic device having a display section, which may include, a housing section configured to house a plurality of batteries, a detection section configured to detect status of each of the plurality of batteries housed in the housing section, a selection section configured to select part of the plurality of batteries for use as a power supply of the electronic device in accordance with the status detected by the detection section, and a display control section configured to display on the display section an indication identifying the part of the plurality of batteries.

Abstract: A circuit for displaying the state of a battery that is almost discharged features a battery, an inductive load, and a controllable switch connected in series. The circuit also includes a display element connected in series with the inductive load and the battery. The controllable switch is opened when a voltage of the battery is lower than a first threshold level and is only closed again when the voltage of the battery is greater than a second threshold level. The circuit may also include a control circuit having a comparator which compares the voltage of the battery with the first threshold level and the second threshold level and triggers the controllable switch accordingly.

Abstract: According to some embodiments, an apparatus for power adapter detection is disclosed. The apparatus includes a first detection module to detect if a first signal from a power adapter is present and in a first voltage range, a second detection module to detect if a second signal from the power adapter is present and in a second voltage range, and a third module to permit a system to be powered by the power adapter if the first signal is present and in the first voltage range and if the second signal is present and in the second voltage range.

Abstract: Methods and systems for battery charging are provided. A system includes a battery charger electrically coupled to at least one battery and a plurality of sensors configured to measure a voltage of the battery, a charging current supplied to the battery, and a temperature of the battery wherein the battery charger is configured to determine a state of charge of the battery using at least one of the plurality of sensors to control gassing of the battery during charging.

Abstract: A charging control device (D) is installed in a piece of electronic equipment (EE) comprising a rechargeable battery (B) and at least an internal application (A) requiring an application current for its operation. This device (D) comprises a charging control module (CCM) arranged to be coupled to a charger (CH), to be fed with a charge current when it is connected to mains, and coupled i) to the battery (B) to control its charge and provide it with a chosen battery current when so required and when its temperature is within a chosen interval, and ii) to the application (A) to provide it with the application current when the electronic equipment (EE) is connected to the charger (CH). The device (D) also comprises a current sensor means (SM) arranged to determine the current consumed by the application (A) and to deliver a first signal representative of this current consumption.

Abstract: The present invention relates to a battery charge circuit (100) in a charge-and-play mode capable to reliably determine the completion of a battery charging operation has been described. Such a determination takes into account the behavior of the battery charge circuit (100) with respect to the temperature, the activity of the circuitry (30) and the source current limitation. Thus, a distinction can be made between a decrease of the battery charge current ICHG below the end-of-charge current level caused by the full-charge state of the battery (20) and by the activation of temperature and current regulation circuits. Furthermore, the battery charge circuit (100) is also configured such that it can be warned both that the activity of the circuitry (30) is to be limited and, by a timer (800) measuring the time interval during which the battery charge current ICHG has been reduced to zero, that the battery (20) is being discharged.

Abstract: A battery pack, a battery charger, a method for charging a battery pack are provided. The battery pack includes a secondary battery, a switch element for controlling charging and discharging the secondary battery, a controller for controlling the switch element, and a communication unit for performing with a battery charger. During charging, an initial charging is switched to a quick charging when a voltage of the secondary battery reaches a predetermined voltage, and the battery charger judges the battery pack as abnormal when the voltage does not reach the predetermined voltage within a timeout period after the initial charging is started. At least one of the timeout period and the predetermined is stored. At least one of the timeout period and the predetermined voltage to be read out is transmitted through the communication unit to the battery charger.

Abstract: A system includes a controllable voltage generator to generate a power supply voltage. The system also includes a system controller to determine a voltage level associated with the power supply voltage, and prompt the controllable voltage generator to generate the power supply voltage. The system includes a floating gate reference device to generate an absolute voltage reference based, at least in part, on the voltage level associated with the power supply voltage. The system can also include analog circuitry to perform one or more electrical operations responsive to the absolute voltage reference from the floating gate reference device.

Abstract: A voltage regulator is disclosed. The voltage regulator includes a comparator for providing a gated output signal; and a state machine for receiving the gated output signal. The voltage regulator further includes at least one switch cell controlled by the state machine, for delivering charge to a load. Accordingly, a voltage regulator in accordance with the present invention yields N times (where N is an integer greater than one) the linear efficiency over typical linear regulators without requiring any external components. Therefore improved regulator efficiency is provided for low power devices.

Abstract: The invention relates to a power converter for converting a first electrical power signal into a second electrical power signal having an output voltage Vout with a DC component comprising a control circuit (320) arranged for measuring the output voltage Vout and controlling the operation of the power converter in dependence thereof. The control circuit (320) comprises voltage level shifting means (326) for generating a measurement voltage signal V2 by adjusting the DC component of the output voltage Vout.

Abstract: A switching regulator includes an inductor, first and second switches, a first rectifier to allow current flowing from a negative voltage output terminal to a connection node between the inductor and the first switch, a second rectifier to allow current flowing from a positive voltage output terminal to a connection node between the inductor and the second switch, a third switch, a first capacitor connected between the negative voltage output terminal and ground, a second capacitor connected between the positive voltage output terminal and ground, and a controller to control switching operations of the first, second and third switches to make each voltages at the negative and positive voltage output terminals to be corresponding predetermined voltages. The control circuit switches the first and second switches on/off simultaneously to make a sum of absolute values of voltages at the negative and positive voltage output terminals a predetermined voltage value.

Abstract: A power-supply control IC is included in a switching power supply which drives to turn on and off a semiconductor switching device connected to a DC power supply in series to supply a predetermined constant voltage to an external load, and is a semiconductor device including a semiconductor circuit which controls on and off of the semiconductor switching device. When a current flowing through the load is abruptly increased to cause an error voltage to exceed a predetermined first threshold voltage after the end of a PWM on-pulse generated in synchronization with a switching cycle, a second PWM on-pulse is generated within the same switching cycle. Furthermore, in a plurality of switching cycles after the switching cycle in which the second PWM on-pulse is generated, the first threshold voltage for comparison with the error voltage is switched to a second threshold voltage higher than the first threshold voltage.

Abstract: A controller for a power processing circuit and a related method of operating the same. In one embodiment, the controller includes a multiplier configured to produce a product of an input current and an input voltage of the power processing circuit. The controller also includes a low-pass filter configured to produce an input power estimate of an input power to the power processing circuit as a function of the product of the input current and the input voltage. In another embodiment, the controller is a power-factor controller and includes a voltage loop compensator configured to produce a voltage compensation signal as a function of an output voltage of the power processing circuit. The controller also includes an input power estimator configured to produce an input power estimate of an input power to the power processing circuit as a function of the voltage compensation signal.

Abstract: A power supply controller (25) is configured to accurately adjust the value of an output voltage of a power supply system (10) responsively to the output voltage increasing to an undesirable value. The controller (25) accurately limits an upper value of the output voltage during a light load condition, and rapidly reduces the value of the output voltage during a light load condition, and different control signals to control the switching of the output transistors facilitates rapidly reducing the output voltage.

Abstract: An I/O regulating circuitry is provided. The I/O regulating circuitry omits the ESD device in a CMOS process with a minimized critical dimension to reduce chip size while still maintaining electrostatic discharge immunity. The I/O regulating circuitry is applied in MLC flash memory applications and the flash controller thereof.

Abstract: A voltage generator is used for generating a voltage reference with high power supply rejection. One embodiment of the circuit includes a voltage regulator and a bandgap voltage circuit and an amplifier. The voltage regulator including an input node is coupled to an external power supply for generating a regulated voltage source. A bandgap voltage circuit includes a first and a second resistor and a first and a second transistor to generate a voltage difference between the base-to-emitter voltages of the first and the second transistors. The second resistor is coupled to the first resistor and the first transistor for generating the first predetermined voltage in response to the voltage difference. An amplifier circuit is coupled to the first transistor of the bandgap voltage circuit for receiving a first amplifying signal and generating an amplified signal so as to regulate the regulated voltage source.

Abstract: A bandgap reference voltage generator circuit includes a substrate made of a semiconductor of a first conductivity type, a first transistor formed on the substrate, a second transistor formed on the substrate and having a base commonly connected to the base of the first transistor, a light absorption region formed on the substrate, having a second conductivity type, and connected in parallel between the collector layer of the second transistor and the substrate and a reference voltage output terminal commonly connected to the bases of the first and second transistor. The area of the collector layer of the first transistor is larger than the area of the collector layer of the second transistor.

Abstract: A reference current generating apparatus is provided which is capable of generating a reference current having no temperature dependency, without increasing a layout area. The reference current generating apparatus includes a constant current generating circuit having a differential amplifier, a constant current generating circuit connected to the constant current generating circuit and having a differential amplifier, and an output circuit connected to the constant current generating circuit for outputting first and second reference voltages. The constant current generating circuit generates a reference current by enabling selection of a mirror ratio of a transistor that conducts summing of a constant current proportional to a thermal voltage, and by enabling switching of a dividing voltage from a resistor to an input of the differential amplifier, to generate a constant current proportional to a diode voltage via a high impedance MOS gate.

Abstract: A switch mode power supply apparatus includes a transformer, a main switching device to adjust a power supply supplied to a primary coil of the transformer, an active clamping circuit to suppress a voltage stress of the main switching device, and a control circuit to control a clamping operation of the active clamping circuit when the switch mode power supply apparatus is in a standby mode. Therewith, it is possible to significantly reduce power consumption of the switch mode power supply apparatus in the standby mode and improve efficiency of the switch mode power supply apparatus.

Abstract: A switchgear cell is disclosed having a first energy store and a second energy store connected in series therewith, having a first, second, third and fourth power semiconductor switch, which are connected in series, wherein the first, second, third and fourth power semiconductor switch are in each case one drivable bidirectional power semiconductor switch with a controlled unidirectional current-conducting direction. The first power semiconductor switch is connected to the first energy store, and the fourth power semiconductor switch is connected to the second energy store. A third energy store is connected to the junction between the first and the second power semiconductor switch and the junction between the third and the fourth power semiconductor switch.

Abstract: The invention relates to a device and a method for counting elementary particles emitted by a fluid, the device comprising a line for transferring the fluid and, outside the line, detection means (6a) for detecting the particles that are attenuated by a wall of the line and/or by this fluid. A counting device according to the invention includes at least one counting portion (4a) of oblong cross section which joins together two adjacent portions of the line having a larger flow section and which has an [internal height (h)/internal width (l)] ratio of 20% or less, in which the internal height and the internal width represent the smallest and largest transverse dimensions respectively of the portion, these being measured along two approximately perpendicular directions, said detection means extending transversely to this portion, facing its entire internal width and on either side thereof.

Abstract: A biomolecule detector and a method thereof are provided to detect the biomolecules in a liquid sample using a field effect transistor (FET) array. The FET array is characterized in that the transistor used has no gate electrode layer, a reference electrode is provided in the space between the transistors in the array instead of the gate electrode layer. Using the FET array, the existence of the biomolecules in the sample can be detected electrically and effectively under the circumstance where an external voltage is applied to flow the biomolecules. Using the FET array to detect the biomolecules, the deviation for each transistor is reduced and the multiplex processing is also possible to measure the plurality of analyzing samples at the same time.

Abstract: An instrument is configured to coordinate execution of a plurality of experiments employing a plurality of source measurement units (SMU's) to characterize a plurality of devices under test (DUT's). Each experiment controller, of a plurality of experiment controllers, is configured to manage one of the plurality of experiments by, at least in part, controlling the SMU's allocated to that experiment. A main controller is configured to interoperate with a host to manage the experiment controllers. For example, the instrument may be configured to provide experiment parameters to the SMU's prior to execution of the experiments. In one aspect, the main controller is configured to receive experiment parameters from a host controller external to the instrument. At least in part based on the received experiment parameters, the main controller configure which experiment controllers are to manage which experiment.

Abstract: Disclosed is an apparatus for measuring a streaming potential of a liquid containing solid matter. Said apparatus comprises a first electrode device relative to the direction of flow, said first electrode device being provided with a first rod-shaped electrode, as well as a second electrode device encompassing a second rod-shaped electrode, and a filter device located between the electrode devices. In order to improve the reproducibility and stability of the test results, the first electrode is embedded in a wall of a duct of the first electrode device so as to protrude into the duct by a maximum of half the diameter thereof perpendicular to the direction of flow.

Abstract: A load measuring circuit including a cable including first and second conductors and a shielding. The conductors are connected by a first end thereof to a load, the shielding is not connected to a ground at the end, and the conductors are connected to a generator by the second end thereof. A transformer includes a first winding connected to a conductor on the second end of the cable, a second winding is connected between a ground and the shielding on the second end of the cable, and a third winding is connected to a current measuring member.

Abstract: A magnetic field sensor for low power applications includes a magnetic field sensing element that, during sample intervals, provides a signal proportional to a sensed magnetic field and also includes a comparator circuit that, during the sample intervals, compares the magnetic field signal to threshold levels to generate a sensor output signal indicative of a strength of the magnetic field. According to a dual sample rate feature, initially the magnetic field signal is sampled at a first predetermined sample rate and, following detection of a transition of the sensor output signal, is sampled at a second, faster predetermined sample rate for a predetermined interval. According to a user-programmable sample rate feature, a user may select to operate the sensor at a fixed, predetermined sample rate or at a user-specified sample rate. The magnetic field sensor may also or alternatively detect the speed and/or direction of rotation of a rotating magnetic article.

Abstract: A control system for use in safety critical human/machine control interfaces is described, more particularly a joystick type control system and particularly a joystick type control system utilizing magnetic positional sensing. The control system provides a control input device having a movable magnet, a pole-piece frame arrangement positioned about the magnet, at least three magnetic flux sensors being positioned in said pole-piece frame arrangement and a monitoring arrangement for monitoring the output signal of each of said at least three sensors.

Abstract: A joint for a motor vehicle has a joint housing (2), with a pivot pin (5) mounted pivotably in same and with an angle-measuring device, which has a magnet (18) and a magnetic field-sensitive sensor, which cooperates with this magnet and by which the angle (?) of the pivot pin (5) relative to the joint housing (2) can be determined. The magnet (18) is fastened to the pivot pin (5) and the sensor to the joint housing (2) or the magnet (18) is fastened to the joint housing (2) and the sensor to the pivot pin (5) at least indirectly. The magnetic field-sensitive sensor is formed by an electric coil (17), which has a core (16) consisting of a magnetic material and which is part of an electrical oscillating circuit (15), by which electromagnetic waves (27) can be sent or are sent.

Abstract: A position sensor with excellent linearity of coil impedance is provided. This position sensor is equipped with a tubular detection coil, a magnetic core movable in the detection coil, a drive circuit for the detection coil, a signal processing circuit for converting a change in impedance of the detection coil into an electric signal, and a shield member disposed around the detection coil. The shield member is a tubular member having a first inner surface for surrounding an axial region of the detection coil, and a second inner surface for surrounding another axial region of the detection coil. The tubular member is formed such that a distance between the second inner surface and the detection coil is smaller than the distance between the first inner surface and the detection coil.

Abstract: A method for locating a device, which produces a field, with a probe assembly affected by the field. The method may involve: placing a device on a first side of a work piece; producing a field with the device through the work piece; using a robot to hold and to place a probe assembly adjacent a second side of the work piece; providing information from the probe assembly to the robot that is used by the robot to move the probe assembly to substantially determine a position of the device; determining a location of a center field axis of the field with the probe assembly; and providing a physical confirmation of the center field axis to a user.

Abstract: A sensor device measures a property of an object. The sensor device comprises a magnetic field generator adapted to generate a magnetic field in at least a part of the object, and at least one magnetic field detector adapted to detect at least one detection signal in response to the magnetic field generated in at least a part of the object. The at least one detection signal is indicative of the property of the object. A direct current or a direct voltage is applicable to the magnetic field generator to generate the magnetic field in at least a part of the object.

Abstract: A flexible array probe is disclosed suitable for use in the non-destructive testing and inspection of test pieces with varying cross-sectional geometries. Array elements—such as, but not limited to, eddy current sensors, piezoelectric sensor elements, and magnetic flux leakage sensors—are mounted on thin alignment fins and coupled together with pairs of pivot mechanisms along the axis of desired rotation. The pivot mechanisms allow rotation in exactly one dimension and force the flexible array probe to align its elements orthogonally to the surface of the structure under test. Alignment and coupling fixtures are also disclosed.

Abstract: Sensor assemblies and methods are described that facilitate the use of a long-range torsional guided-wave inspection system for inspecting pipes, tubes, or other longitudinal cylindrical structures, with a partial excitation and detection around the pipe circumference. The sensor assemblies comprise a plate-type magnetostrictive sensor probe positioned beneath a compressible/expandable bladder and an inverted U-shaped frame that retain and position the sensor probe against the external wall of the pipe under inspection. Preferably, a magnetostrictive strip is positioned in direct contact with the pipe wall over which the plate magnetostrictive sensor probe is positioned. The probe is preferably curved to match the curvature of the external surface of the pipe. A pad may be positioned between the probe and the magnetostrictive strip to improve compliance with irregular pipe surfaces.

Abstract: A method to obtain a free induction decay signal using includes inducing a static magnetic field in a sample volume. A radio frequency (RF) magnetic field is then induced in the sample volume. The RF magnetic field has parameters selected to minimize the contribution of inhomogeneity to the static magnetic field to a free induction decay time. The free induction decay signal is then detected from the sample volume. In one example, prior to inducing the RF magnetic field, a reorienting radio frequency magnetic field is induced in the sample volume to reorient magnetic spins by a first selected angle. The inducing the RF magnetic field in this example has parameters selected to reorient spins by a second angle. The inducing the RF magnetic field and detecting the free induction decay signal are repeated until nuclear magnetic equilibrium is substantially attained.

Abstract: A passenger inspection system includes a metal detection sensor integrated with a quadrupole resonance sensor and configured to detect weapons and/or explosives that may be present proximate the feet and/or lower legs of a person. Additionally, a weapons detection sensor may include one or more pairs of transmit coils and receive coils that are vertically mounted to the interior sidewalls of the passenger inspection system and configured to detect symmetrical and nonsymmetrical threats present on a portion of a person's legs. Methods for operating embodiments of the passenger inspection system are also disclosed.

Abstract: A biological detector includes a conduit for receiving a fluid containing one or more magnetic nanoparticle-labeled, biological objects to be detected and one or more permanent magnets or electromagnet for establishing a low magnetic field in which the conduit is disposed. A microcoil is disposed proximate the conduit for energization at a frequency that permits detection by NMR spectroscopy of whether the one or more magnetically-labeled biological objects is/are present in the fluid.

Abstract: A magnetic resonance imaging apparatus configured to scan a subject in order to collect magnetic resonance signals from the subject in a magnetostatic field space, the magnetic resonance imaging apparatus includes a scanning unit configured to execute an imaging pulse sequence after executing a preparation pulse sequence to transmit preparation pulses.

Abstract: Disclosed is a system and method for imaging strain of tissue, such as the heart, in a quantitative manner. The present invention provides images of strain, which corresponds to heart function, by tagging a tissue region of interest, and acquiring multiple images by tuning an MRI RF receiver to frequencies above and below the tagging frequency. Depending on the tagging spatial frequency, and the spread between the high- and low-tuning frequencies, linear measurements of strain may be made on a pixel by pixel basis. By selectively tagging the tissue of interest by use of selective excitation, images may be acquired sufficiently fast to provide anatomical and functional imagery within a single heartbeat. By acquiring additional images, dead tissue may be differentiated from contracting tissue as well as blood.

Abstract: The present invention relates to a magnetic resonance imaging (MRI) system. The basic components of a MRI system are the main magnet system, the gradient system, the RF system and the signal processing system. The gradient system comprises normally three orthogonal primary coils and three orthogonal shield coils. The shield coils of the gradient system are usually designed to minimize the generation of eddy currents within the main magnet system. However, such a gradient system designed to minimize the generation of eddy currents is not optimal with respect to mechanical vibrations inside the gradient system. It is also possible to design the shield coils of the gradient system in a way to minimize mechanical vibrations inside the gradient system. However, such a gradient system is not optimal with respect to the minimization of eddy currents.

Abstract: A system for detecting electromagnetic noise in a magnetic resonance imaging (MRI) scanner environment includes an antenna configured to detect electromagnetic noise. The antenna includes a first conducting loop and a second conducting loop oriented perpendicularly to the first conducting loop. The system also includes a noise correction system coupled to the antenna and configured to receive noise signals from the antenna.

Abstract: There is provided an RF coil capable of resonating or tuning two frequencies, having uniform spatial sensitivity and having a small spatially occupied volume, especially an RF coil suitable for a high magnetic field MRI apparatus. A coil apparatus is made up of a plurality of linear conductors 200, 201 arranged around a central axis and two ring conductors 202, 203 connected to the respective ends of the plurality of linear conductors 200, 201 and capacitors are inserted in the linear conductors 200, 201 and ring conductors 202, 203. The plurality of linear conductors are made up of conductors 200 located near the central axis and conductors 201 located far from the central axis and the ring conductors 202, 203 have star-like polygonal shape so that the linear conductors are arranged alternately.

Abstract: A magnetic resonance apparatus has a basic field magnet that generates a basic magnetic field with a homogeneity region of the basic magnetic field in which the basic magnetic field is homogeneous and with a maximum real measurement volume contained in the homogeneity region. The apparatus has a movable patient bed and a control unit that controls the movable patient bed. The maximum measurement volume thereby exhibits a cylindrical shape. A virtual total measurement volume that is greater than the maximum real cylindrical measurement volume can be generated by the control unit together with the movable patient bed.

Abstract: A resistivity array having a modular design includes a transmitter module with at least one antenna, wherein the transmitter module has connectors on both ends adapted to connect with other downhole tools; and a receiver module with at least one antenna, wherein the transmitter module has connectors on both ends adapted to connect with other downhole tools; and wherein the transmitter module and the receiver module are spaced apart on a drill string and separated by at least one downhole tool. Each transmitter and receiver module may comprise at least one antenna coil with a magnetic moment orientation not limited to the tool longitudinal direction. A spacing between the transmitter and receiver module may be selected based on expected reservoir thickness.

Abstract: A phase error in measurements made by a resistivity logging tool is estimated by positioning the tool above a conducting surface. Deviation of the measured phase difference between the transmitter and the receiver from 90° gives the phase error in the electronics. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A multi-mode oil base mud imager for use in non-conductive drilling fluid includes at least one current source-a current return pair, and one or more monitor electrodes not located between the current source and the current return of the current source-current return pair. Where more than one current source-current return pair is included, the tool is capable of multiple depths of investigation into surrounding formation. This data can be used as a gauge to establish the reliability of the data and to determine the resistance of the invaded zone around the borehole, as well as standoff distance of the tool from the borehole wall.