Abstract: An apparatus measures moisture content of cotton based upon rates of electrical charges flowing through the cotton. The apparatus includes a moisture sensor having first electrodes, second electrodes, and ground electrodes which are interdigitated between the first and second electrodes. The apparatus also includes a moisture content determination circuit that provides first electrical charges to the first electrodes, and second electrical charges to the second electrodes. The moisture content determination circuit determines the rate of electrical charge flowing from each of the first and second electrodes through the cotton to the ground electrodes, and determines the moisture content of the cotton based upon the rates of electrical charges flowing through the cotton. By thus applying first electrical charges to the first electrodes and second electrical charges to the second electrodes, the apparatus accurately measures the moisture content of the cotton over a wide range of moisture contents.

Abstract: An apparatus for detecting topographic variations on an object such as a finger includes an array of sensing elements disposed on a substrate which each have a parasitic capacitance. An insulating receiving surface is disposed over the array of sensing elements and is adapted to receive the object such that a sensing element and a portion of the object located thereabove creates a measurable change in capacitance with respect to the parasitic capacitance. An electronic circuit is coupled to the array of sensing elements for measuring the measurable change in capacitance.

Abstract: The present invention relates to a method for measuring an ion flow from a plasma to a surface in contact therewith, consisting of measuring the rate of discharge of a measuring capacitor connected between a radiofrequency voltage source and a plate-shaped probe in contact with the plasma.

Abstract: A touch sensor switch that responds to touching, or even to the proximity of an object, is disclosed. The switch includes a number of capacitance elements, or touch pads, that produce an effective capacitance dependent upon the physical proximity of the object. A microcontroller under control of a program stored in a read-only memory causes its I/O port to set a transient voltage on each capacitance element as a logic level. Each transient voltage is at variance with the capacitive element's preferred voltage level. The program then reads the I/O port, and hence the logic levels of the capacitance elements, as the capacitive elements revert to their preferred voltage levels, and calculates the proximity of the object, or touching, from relationships among recorded signals. The circuit may also be embodied in an application specific integrated circuit.

Abstract: The invention relates to an apparatus and method for detecting electrical charge with a long integration time and in particular to a sampling method which reduces noise that affects the accuracy of the measurement of the total charge. The apparatus samples the charge on the capacitor at the start of the integration period to obtain a sample proportional to a first noise component. It then samples the charge on the capacitor at the end of an integration period and subtracts the noise component sample from the integrated charge sample to obtain a measure of integrated charge to the relative exclusion of the noise component. The circuit uses a folded cascode amplifier and at least one correlated double sampling circuit. The charge detector can be used with any apparatus which generates electrical charge in response to an input including for example, a photodetector, photomultiplier, ion detector, e beam detector and piezoelectric charge detector and arrays of such devices.

Abstract: A time-domain dielectric spectroscopy device and method are described wherein measurements are taken of the absorption and dielectric response function of a dielectric material in order to identify dielectric materials.

Abstract: A quality and/or flow meter employs a capacitance probe assembly for measuring the dielectric constant of flow stream, particularly a two-phase flow stream including liquid and gas components. The dielectric constant of the flow stream varies depending upon the volume ratios of its liquid and gas components, and capacitance measurements can therefore be employed to calculate the quality of the flow, which is defined as the volume ratio of liquid in the flow to the total volume ratio of gas and liquid in the flow. By using two spaced capacitance sensors, and cross-correlating the time varying capacitance values of each, the velocity of the flow stream can also be determined. A microcontroller-based processing circuit is employed to measure the capacitance of the probe sensors. The circuit employs high speed timer and counter circuits to provide a high resolution measurement of the time interval required to charge each capacitor in the probe assembly.

Abstract: A thermal head of a thermal printer has plural heating elements arranged along a line and connected in parallel with one another. A respective one of the heating elements is connected to one of plural heat control switches, which are selectively turned on/off for driving the heating elements individually by applying electrical energy to generate heat. To measure resistance data of at least one of the heating elements, a capacitor is connected in parallel with the plural heating elements. A reference resistor is connected in parallel with the plural heating elements and the capacitor. The capacitor is charged, and then discharged via the reference resistor or the one of the heating elements. A voltage across the capacitor is detected. An amount of discharging time required to decrease the capacitor voltage from a predetermined high voltage to a predetermined low voltage is measured while the capacitor is discharged, in association respectively with the reference resistor and the heating elements.

Abstract: An output open circuit test method including the steps of inputting the data of a predetermined charging current upper limit value and a predetermined test voltage and a predetermine test charging current time zone into a test apparatus, then employing a high voltage to the test sample, and then driving the test apparatus to measure the current between two ends of the test sample and to compare the measured current value with the predetermined charging current upper limit value, and then letting the test apparatus to start testing the leakage current of the test sample when the measured current value is below the predetermined charging current upper limit value.

Abstract: A diagnostic circuit for checking a capacity of a backup condenser having a check circuit in which the clamp means includes a Zener diode and a transistor connected in parallel with the backup condenser and the current flowing through a charge resistor, the Zener diode and the transistor during a time B that the transistor is turned on by a microprocessor, results in the terminal voltage of the backup condenser to be clamped to a predetermined clamp voltage.

Abstract: An RF matching network provides matching between a charged first transmission line and a relay circuit which is switched to connect the charged transmission line to one end of a second transmission line to generate a high-voltage, high-current test pulse for a DUT connected to the other end of the second transmission line. A low pass filter section of the RF matching network suppresses transient and ringing signals which might pass through the parasitic capacitance of the relay circuit and which trigger the prematurely trigger the DUT. To remove residual charge after discharging the first transmission line, the transmission line is grounded with a GND relay before leakage tests are conducted to prevent electrically stress of destruction of leakage testing circuitry if the residual charge is not dissipated before testing for leakage.

Abstract: An apparatus for inspecting an electric component in an inverter circuit has a DC power supply for supplying a direct current to a given position in an inverter circuit, a voltage detector for detecting a voltage at a given position in the inverter circuit, a current detector for detecting a current flowing at a given position in the inverter circuit, a switching circuit for changing positions at which the direct current is supplied from the DC power supply, positions at which the voltage is detected by the voltage detector, and positions at which the current is detected by the current detector, and a controller for outputting a switching signal to the switching circuit. The switching circuit is controlled by the controller to charge an electrolytic capacitor in an inverter circuit with a current from the DC power supply. The electrolytic capacitor is determined as to its quality by determining whether the calculated electrolytic capacitance of the electrolytic capacitor falls within a preset range or not.

Abstract: A capacitance sensor assembly for use with a label detection and registration system for detecting a lateral edge of a label on a web bearing a plurality of such labels and moving in a longitudinal direction through a capacitance gap in the sensor assembly. The capacitance sensor assembly includes a reference plate electrode, and a pair of sensor electrodes extending substantially parallel to and spaced apart from the reference plate electrode to form the capacitance gap. The pair of sensor electrodes has a differential capacitance, when the web bearing the plurality of labels thereon is in the capacitance gap, which is used to provide a signal indicative of the lateral edge of the label.

Abstract: In a system which comprises an apparatus, having a connection device with connection contacts, and at least one peripheral device which can be connected to the apparatus and comprises a counter-connection device which can be detachably connected to the connection device and comprises counter-contacts, at least one counter-contact being connected to a resistor provided in the peripheral device, the apparatus comprising a circuit arrangement for determining the value of a resistor, the circuit arrangement is additionally arranged to generate at least one control information item for the peripheral device which comprises an evaluation device for evaluating the control information.

Abstract: The circuit arrangement and method is for measuring a difference in capacitance between a first capacitance (C.sub.1) and a second capacitance (C.sub.2). A hitherto necessary compensation of a plurality of parasitic effects has become unnecessary due to isolated measurement of an unwanted capacitance (C.sub.P) with which parasitic effects, to which the first capacitance (C.sub.1) and the second capacitance (C.sub.2) are subject, are modelled. When an evaluation logic (AL) realized in digital form is employed, only one counter unit wherein a binary value proportional to the respectively measured capacitance is counted need be provided. By cyclical measurement of the unwanted capacitance (C.sub.P), the first capacitance (C.sub.1), the second capacitance (C.sub.2) and, at the end, the unwanted capacitance (C.sub.P) are determined. The unwanted capacitance (C.sub.P) is compensated when the counter unit respectively counts backward when "counting" the unwanted capacitance (C.sub.P) but otherwise counts forward.

Abstract: A humidity sensing circuit uses a humidity sensitive capacitor as a circuit element in an RC control network for a timer/multivibrator circuit. As the voltage on one plate of the capacitor swings between charge and discharge voltage limits and corresponding triggering voltage values for the timer/multivibrator, the other plate of the capacitor is held at a voltage substantially midway between the charge/discharge voltage limits to thereby cancel out any time averaged net DC component on the capacitor, to reduce stress thereon and extend its life. A power-down feature is disclosed for removing all voltage across the capacitor between sensing intervals.

Abstract: The invention relates to an apparatus and method for detecting electrical charge with a long integration time and in particular to a sampling method which reduces noise that affects the accuracy of the measurement of the total charge. The apparatus samples the charge on the capacitor at the start of the integration period to obtain a sample proportional to a first noise component. It then samples the charge on the capacitor at the end of an integration period and subtracts the noise component sample from the integrated charge sample to obtain a measure of integrated charge to the relative exclusion of the noise component. The circuit uses a folded cascode amplifier and at least one correlated double sampling circuit. The charge detector can be used with any apparatus which generates electrical charge in response to an input including for example, a photodetector, photomultiplier, ion detector, e beam detector and piezoelectric charge detector and arrays of such devices.

Abstract: An electrical discharge state detecting device for an electrical discharge machining machine which detects an electrical discharge state during an electrical discharge machining operation. The detecting device includes a high-pass filter for detecting a high-frequency component superimposed on an electrical discharge voltage or an electrical discharge current at a machining clearance between an electrode and a workpiece, a rectifying circuit for outputting a rectified component of the high-frequency component, a first integration circuit for integrating the rectified component, a reference voltage circuit, a second integrating circuit for integrating the reference voltage, a comparator for comparing the two integrated values, an electrical discharge generation detecting circuit for controlling starting and ending of the integrating circuits, a logic circuit, and a delay circuit and reset circuits.

Abstract: A ratiometric circuit (40) includes a differential capacitive sensor (42) for sensing a change in capacitance, a differential capacitive detector (46) operatively connected to the differential capacitive sensor for detecting a change in the capacitance of the differential capacitve sensor, an error voltage generator (48) operatively connected to the differential capacitve detector for generating a corrective voltage in response to the detected change in capacitance, and a bias circuit (50) operatively connected to the differential capacitive sensor for generating a bias voltage inversely proportional to and independent of a supply voltage for maintaining the ratiometricity between an output voltage of the differential capacitive sensor and the supply voltage.

Abstract: A capacitive field sensor, which may be used for the control of a water supply valve in a basin or fountain, employs a single coupling plate to detect a change in capacitance to ground. The apparatus comprises a circuit for charging a sensing electrode and a switching element acting to remove charge from the sensing electrode and to transfer it to a charge detection circuit. The time interval employed for the charging and discharging steps can vary widely. Usually at least one of the charge or discharge pulses is on the order of a hundred nanoseconds, and is shorter in duration than a characteristic conduction time for a body of water disposed about the sensing plate. Thus, the sensor can detect the presence of a user near a controlled faucet without being subject to measurement artifacts arising from standing water.

Abstract: A standard resistor having a known resistance value is connected to one transistor in a drive IC. The drive IC has a plurality of transistors each controlling the on/off of a heating element. The saturation voltage of each transistor is generally the same. One of a plurality of transistors is turned on, and a discharge time required for a capacitor to discharge via a standard resistor or via each heating element and lower its voltage to a predetermined voltage is measured. The resistance value of each heating element is determined from a ratio of a discharge time via each heating element to a discharge time via the standard resistor and the resistance value of the standard resistor. A difference between the standard resistance value and a resistance value of each heating element generates a bias heat energy error during bias heating and an image heat energy error during image heating. In accordance with these heat energy errors, bias data for generating a heat energy immediately before coloring is corrected.

Abstract: A plurality of electrical circuit components having capacitance, e.g. ceramic capacitors, are tested simultaneously in a corresponding plurality of test channels. They are stressed by a variable voltage source that can produce an electrical potential selected from a wide range from low potential to high potential. For example the range of selectable potentials can be 1000 volts with a resolution of 1 volt. The charge current by which a component accumulates a charge is controlled to a selected linear rate by a current controller. Voltage sensors and current sensors measure accumulated charges and leakage current, respectively. The current sensor can be selectively sensitized to a plurality of anticipated leakage current ranges. In addition, the selected potentials can each be applied to the components in a single step or can be applied over time in ramp fashion.

Abstract: A capacitance detector comprises switches for charging and discharging a sensing part, an integrator constituted by a condenser and an operational amplifier for integrating a charging current or a discharging current which is generated according to the charging and discharging the sensing part, a switch for charging an output voltage of the operational amplifier and for feedbacking an electric charge to the integrator, and a condenser. The capacitance detector can be provided by the operational amplifier having a low response performance and a small output current and no hold sample circuit, thereby a circuit scale of the capacitance type sensor can be made small.

Abstract: A dual-slope measuring circuit for measuring an unknown resistance. A first time measurement measures the time which is needed to charge a capacitor to a first reference voltage (Uref.sub.1) via a reference resistor. A second time measurement measures the time which is needed to charge the capacitor again to the first reference voltage (Uref.sub.1) but now via the parallel arrangement of the reference resistor and the unknown resistance. The value of the unknown resistance is determined from the ratio between the two time intervals thus measured. The time measurement is not started until the capacitor voltage (Uc) on the capacitor has passed a second reference voltage (Uref.sub.2), where the second reference voltage has a value between the first reference voltage and the capacitor voltage (Uc) appearing across the capacitor immediately after discharge of the capacitor.

Abstract: An oscillator circuit includes a gate G.sub.11 of C-MOS type (Q.sub.1, Q.sub.2, and the like) having the function of increasing an operating current i with increasing operating frequency. A humidity sensor HS changing electric impedance thereof in accordance with humidity is arranged in part of the oscillator circuit. The oscillator circuit converts a change in humidity into a change in frequency, causes the gate G.sub.11 to convert the change in frequency into a change in operating current i, and outputs the converted change in operating current i. Further, in order to increase the change in operating current i due to the change in frequency, a series circuit consisting of a capacitor C.sub.13 and a resistor R.sub.17 is connected to the gate G.sub.11 as a capacitive load.

Abstract: An apparatus for collecting data related to the internal pressure of a fuel tank in a motor vehicle includes an analog pressure transducer that outputs a signal to charge a capacitor to a level proportional to the pressure in the fuel tank of the vehicle. A programmable microprocessor signals a gate to open a communication path between the capacitor and a discharge resistor, then monitors the number of clock counts that occur before the voltage across the discharge resistor drops below a reference voltage. The microprocessor uses the clock count to determine the absolute pressure within the fuel tank and transmits it to a central vehicle computer via a multiplexed data bus system.

Abstract: An apparatus for sensing two parameters of a hydraulic system having a hydraulic line includes a pair of electrodes contained within the line and oppositely spaced, forming a capacitor. The apparatus alternately produces first and second charging currents having first and second constant magnitudes, respectively, and charges the capacitor to respective first and second predetermined voltages. The apparatus detects the time needed to charge to the first and second predetermined voltages and produces a pulse width modulated signal having a series of alternating first and second pulses. The first and second pulses are indicative of the first and second parameters, respectively. The first pulse is defined by the time required to charge the capacitor to the first predetermined voltage. The second pulse is defined by the time required to charge the capacitor to the second predetermined voltage. The apparatus determines the two parameters as a function of the pulse width modulated signal.

Abstract: In a capacitive sensor system, first and second driving signals opposite in phase are applied to a sensor capacitor and a reference capacitor, respectively, which are both connected to a switched capacitor circuit. An output signal of the switched capacitor is sampled by two sample-and-hold circuits which are operated in different phases of the driving signals. A differential amplifier generates a sensor signal in response to the difference in potential between the outputs of the sample-and-hold circuits.

Abstract: In a circuit arrangement for determining differences in capacitance, two capacitors (1,2) are alternately connected to an integrator with differential amplifier (3) whose input current is positive (+I) when the first capacitor (1) is integrated or negative (-I) when the second capacitor (2) is integrated, whereby the switches (5,6,7) are synchronously switched. The differential amplifier keeps the voltages at the two capacitors the same. A clocked control device (4) controls the synchronous switching and separately measures and adds the respective charging and discharging times and, as warranted, measures and adds the output voltage of the integrator and controls the last charging cycle such that the voltage at the capacitors is subsequently equal to the initial voltage. The relative or absolute differences in capacitance are calculated from the identified sums and can be digitally output.

Abstract: An automatic self-calibration system for digital teraohmmeter wherein a built-in standard resistor is provided. The system is able to calibrate the values of the key components by taking the standard resistor as reference. The calibration procedure of the invention is controlled by a computer and executed automatically. The system is used to measure high-resistance standards up to 10.sup.15 .OMEGA. where the standard uncertainty does not exceed 100 ppm after a traceable calibration.

Abstract: A capacitance measuring device comprises a MOS transistor having a source, drain, and gate; a first capacitor C.sub.1 connected between said gate and said drain so that charge is coupled from said drain onto said gate; and a second capacitor C.sub.2 for connection to a source of gate voltage V.sub.G and connected to said gate. One of the first and second capacitors has a known capacitance and the other has an unknown capacitance. A DC voltage is supplied between the source and drain to cause a saturation current to flow therebetween. The ratio .delta.V.sub.G /.delta.V.sub.d for the saturation current, where V.sub.G is the applied gate voltage, and V.sub.d is the drain voltage is determined and the unknown capacitance is derived from the relationship C.sub.1 /C.sub.2 =-.delta.V.sub.G /.delta.V.sub.d.

Abstract: In a process and a circuit arrangement for measuring the resistance of a resistance sensor, for instance a wetness sensor, via a rate of change of the charge of a capacitor, a measurement cycle consisting in each case of a charging of a capacitor, a discharging of the capacitor over the resistance sensor, and thereupon a measurement of the charge remaining in the capacitor, the direction of the discharge current through the resistor changes from measurement cycle to measurement cycle.

Abstract: An electric fence energizing apparatus is described in which a chargeable capacitor is connected to the primary winding of a transformer. The secondary winding of the fence is connected to receive pulses at the discharge of the capacitor, the discharge time serving as a measure of the voltage of the corresponding output pulse on the fence. The primary winding of the transformer is divided into two oppositely connected windings. The capacitor is arranged to be discharged through a first one of the primary windings. A voltage determined by the discharge of the capacitor is produced over the second of the primary windings during the discharge process. A measuring unit measure the time of the duration of this voltage over the second winding determined by the discharge of the capacitor.

Abstract: An apparatus and method for measuring the variation in the capacitance of a capacitive sensor. The apparatus and method include means for constantly applying a constant electrically current to an electrode of the capacitor and means for generating a first series of timing pulses. The voltage on the capacitor is compared to a reference voltage and an electrical signal is generated when the voltage on the capacitor reaches a first voltage which exceeds the reference voltage. The first series of timing pulses emitted by the generating means from the time that the charging of the capacitor beings until the electrical signal is generated is counted and an output signal is generated corresponding to the number of timing pulses counted. An application of the sensor to the measurement of the change in length of a telescoping device such as a shock absorber is also disclosed.

Abstract: A capacitance measuring device incorporates the integrating analog-digital converter circuit of a handheld meter. The capacitance measuring device charges an unknown capacitance with a constant current until the voltage across the unknown capacitor reaches a predetermined voltage. At the same time, a reference voltage is applied to the input lead of an integrating circuit of the integrating analog-digital converter such that a corresponding proportional charge is stored in the feedback capacitor of the integrating circuit. The negative of the reference voltage is then applied to the integrating circuit so that charge is removed from the feedback capacitor at the same rate as the feedback capacitor was charged. A counter is used to determine the number of clock pulses it took to completely discharge the feedback capacitor and hence a reading of the unknown capacitance can be determined from the equation C.sub.X =I.sub.CHARGE *T.sub.2 /V.sub.TRIP.

Abstract: A time varying excitation current (413) is provided to one side of a capacitive sensor (417), and two signal paths (420,430) are provided between the other side of the capacitive sensor (417) and signal conditioning circuitry (412), each signal path differing from the other according to its polarity. The signal paths conduct monopolar signals from the capacitive sensor the magnitude of which are directly related to the capacitance of the sensor, and bi-polar signals the magnitude of which are directly related to the stray capacitance in the signal lines. The combined monopolar and bi-polar signal currents on each signal line are converted into voltage signals (422,433), and the voltage signals are thereafter differenced (460) to provide a null bi-polar output while providing a constant monopolar voltage level the magnitude of which is directly related to the probe capacitor current.

Abstract: A circuit and method is disclosed which determines the physical position of a selected resistance setting of a mechanical variable resistive component, such as a potentiometer, between its mechanical limits as a ratio of its selected resistance and its total resistance. The circuit includes a potentiometer, a capacitor and a microprocessor, which form a charging circuit. The microprocessor has three I/O pins, which are connected to the three terminals of the pot. The capacitor is connected in series to the pot, so that it can be charged by a voltage signal from the microprocessor either across the selected resistance of the pot's wiper or across the entire resistance of the pot. The microprocessor executes a program, which embodies the method of this invention.

Abstract: A sense circuit for detecting charge on a TFT/LCD cell capacitor, which comprises a first, integrating circuit attached to the TFT/LCD cell capacitor through a data line, wherein the data line is connected to the cell capacitance through a thin film transistor is disclosed. The thin film transistor including a gate, a drain and a source, wherein the source is connected to the cell capacitor and the drain is connected to the data line. A first, gate supply voltage adapted to drive the gate of the thin film transistor. And a reset circuit adapted to reset the integrating circuit. This embodiment may further include a source for charging said cell capacitor prior to measuring the charge. Further, a method of testing a partially constructed electronic circuit, for example the cell of an LCD, prior to installation of the backplate is also disclosed. The partial circuit comprising an array of contact electrodes, for example cell pad electrodes and an array of address electrodes, for example gate electrodes.

Abstract: A highly accurate system to measure the level of material in a vessel. A probe is provided in the vessel. The vessel and the probe are at different potentials so as to create a capacitance therebetween. The air and materials in the vessel act as dielectrics. As the material level varies, so does the capacitance. This capacitance is subjected to a charge-discharge-charge cycle yielding integrated net neutral charge. The duration of the cycle is compared to a reference time to determine capacitance, which is proportional to the level of material in the vessel.

Abstract: An apparatus and a method for inspecting a thin film transistor easily and securely with good reproducibility without adverse effect on elements of the thin film transistor even if the thin film transistor is not provided with a capacitative element. The apparatus includes an inspection signal generating device for inputting drive pulse signals and test pulse signals, respectively to a gate electrode; a test voltage generating device for inputting a test voltage to the source electrode in synchronism with the drive pulse signals; an external electrode arranged to be opposed to the drive electrode and forming therebetween a capacitance for storing test charges; and an electric signal detecting device for detecting electric signals output from the capacitance formed between the drive electrode and the external electrode to the source electrode in synchronism with test pulse signals to be input to the gate electrode.

Abstract: A method of testing if the wiring or state of a TFT and LCD is abnormal includes the following steps: In a first operation, a TFT is turned on for a given time period to charge the cell capacitor connected to an LCD through the data line thereof. Next, the TFT is turned off, maintaining the charged condition. Then, the TFT is turned on again for a given time period T to release the stored electric charge through the source, drain and a grounded resistor. Changes with time in the output of source current (i.sub.1) or voltage (V.sub.1) induced by the discharge are input into a computer. In a second operation, the TFT is turned on for a given time period without charging the cell capacitor through the data line. After turning off the TFT for the same time as the first operation, the TFT is turned on again for a given time period to release the stored charge through the source, drain and grounded resistor. Then, changes with time in the output of source current i.sub.2 or source voltage V.sub.

Abstract: When setting up the thermal head, respective resistances of the heating elements of the thermal head are measured, and a difference between the resistance value of each heating element and the smallest resistance value is detected. A predetermined amount of resistance trimming energy for lowering the resistance of the heating element by a predetermined constant amount is applied to each heating element for a number of times which depends on the detected difference in the resistance of the heating element from the smallest resistance, to trim the resistance of the heating element down to the smallest resistance.

Abstract: A pulse discharge circuit for pulse testing an integrated-circuit device under test (DUT) is provided which uses three separate switching relays S1, S2, and S3, which are operated in a predetermined sequence. For charging the capacitance of a pulse-forming transmission line, the relay contact of S1 is closed while the relay contacts of relays S2, S3 are both open. For discharging the charge on the transmission line to form a test pulse, the relay contact of S1 is first opened, and the relay contact of S2 is then closed while the relay contact of S3 is open. After each test pulse is generated and applied to a DUT, the condition of the DUT is determined by a leakage current measurement. The relay contact S2 is opened to isolate the pulse generator circuit and then the relay contact S3 is closed.

Abstract: A circuit compares a difference between first and second voltages to a predetermined voltage. The circuit comprises an amplifier having first and second inputs. First and second capacitors are each coupled at one end to the first input of the amplifier. The first capacitor is charged with the first voltage and subsequently discharged. The second capacitor is charged with a first reference voltage and subsequently discharged. Third and fourth capacitors are each coupled at one end to the second input of the amplifier. The third capacitor is charged with the second voltage and subsequently discharged. The fourth capacitor is charged with a second reference voltage and subsequently discharged.

Abstract: A method of screening ceramic capacitors. The method includes the steps of: charging the ceramic capacitors by applying a constant d.c. voltage which is larger than the rated voltage and smaller than the breakdown voltage; and leaving the charged ceramic capacitor in a temperature around the maximum working temperature for a specific period of time with both terminals of each ceramic capacitor opened electrically; and eliminating defective capacitors whose residual voltage values are smaller than a specific voltage value.

Abstract: A capacitance-sensitive switch unit including a capacitive element operable to produce an effective capacitance dependent upon the physical proximity of objects relative thereto, a first selector signal input connected to the capacitive element to enable a first input signal to charge the effective capacitance, a threshold signal producing circuit connected to the capacitive element, for producing a threshold signal which is rendered active when the effective capacitance charges to a pre-defined potential, a switching circuit for selectively connecting the capacitive element to the threshold signal producing circuit in response to a switching signal and a discharge control circuit connected to the capacitive element, for selectively discharging the effective capacitance independently of the input signal, in response to a discharge signal. Also disclosed is a switch array employing structure similar to the above.

Abstract: An apparatus for inspecting an electric component in an inverter circuit has a DC power supply for supplying a direct current to a given position in an inverter circuit, a voltage detector for detecting a voltage at a given position in the inverter circuit, a current detector for detecting a current flowing at a given position in the inverter circuit, a switching circuit for changing positions at which the direct current is supplied from the DC power supply, positions at which the voltage is detected by the voltage detector, and positions at which the current is detected by the current detector, and a controller for outputting a switching signal to the switching circuit. The switching circuit is controlled by the controller to charge an electrolytic capacitor in an inverter circuit with a current from the DC power supply. The electrolytic capacitor is determined as to its quality by determining whether the calculated electrolytic capacitance of the electrolytic capacitor falls within a preset range or not.

Abstract: The value of an unknown voltage is measured by applying a time-varying current from a reference voltage source through a resistor to a capacitor thereby to increase the voltage across the capacitor as a function of time, measuring the time Tr required for the voltage across the capacitor to reach a selected reference voltage when current from the reference voltage source is applied to the capacitor, restoring the voltage across the capacitor to its initial state, applying a time varying current from an unknown voltage source through a resistor to the capacitor thereby to increase the voltage across the capacitor as a function of time, measuring the time Tb required for the voltage across the capacitor to reach a selected reference voltage when current from the unknown voltage source is applied to the capacitor and calculating the unknown voltage from the times Tr and Tb.

Abstract: A resistance measuring method and device for a thermal head, and a thermal printer using the resistance measuring device. From among a plurality of parallel connected heating elements of the thermal head, the heating element whose resistance is to be measured is set ON, while other heating elements are set OFF. A capacitor connected in parallel to the heating elements is discharged through the conductive one of the heating elements, while being disconnected from a power supply for charging the capacitor, and a discharge time required to discharge the capacitor down to a predetermined voltage level is measured. A resistance value of the heating element is calculated based on the measured discharge time.

Abstract: A highly accurate system to measure the value of a capacitor using proportionality against a time base reference. The capacitor under test is linearly sequentially charged in three discrete steps yielding integrated net neutral charge as well as a delay for discharging dielectric absorption during each measurement cycle.