Abstract: A method for determining a property of an insulating film is provided. The method may include obtaining a charge density measurement of the film, a surface voltage potential of the film relative to a bulk voltage potential of the substrate, and a rate of voltage decay of the film. The method may also include determining the property of the film using the charge density, the surface voltage potential, and the rate of voltage decay. A method for determining a thickness of an insulating film is provided. The method may include depositing a charge on the film, measuring a surface voltage potential of the film relative to a bulk voltage potential of the substrate, and measuring a rate of voltage decay of the film. The method may also include determining a thickness of the film using the rate of voltage decay and a theoretical model relating to leakage and film thickness.

Abstract: In some aspects, the present invention provides a method for estimating at least one measurement/object property of a metal object. The method includes generating a time-varying eddy current in a wall of the metal object utilizing a pulsed-signal transmitter. The method further includes measuring the time-varying eddy current, fitting the time-varying measured eddy current to a parameterized polynomial, and interpreting the parameterized polynomial to determine one or more measurement/object properties of the metal object.

Abstract: An apparatus for measuring the thickness of thin-film cause electron beams of first and second energies to strike thin-film to be measured that is formed on a silicon substrate, and measures the first substrate current value of current flowing in the substrate when it is struck by an electron beam of a first energy and the second substrate current value of current flowing in the substrate when it is struck by an electron beam of a second energy. The thin-film measuring apparatus obtains reference data indicating a relationship between the film thickness and a reference function having as variables the substrate current for the case of an electron beam of the first energy striking a standard sample and the substrate current for the case of an electron beam of the second energy striking the standard sample, and calculates the thickness of the thin-film under measurement based on the first and second substrate current values, giving consideration to the reference data.

Abstract: A digital measuring head in a measuring apparatus measures a work by making a contact element abut to the work. The digital measuring head includes an arm supported rotatably around a support point arranged on a base; a finger having the contact element at a tip end and mounted to a tip end portion of the arm; and a scale and a read head, one of which is provided at a rear end portion of the arm and the other of which is arranged on the base. Displacement of the contact element which contacts with the work is measured with the scale and the read head. Thereby, the measuring head can perform measurement in a wide range and becomes excellent in the actuation property and the temperature property, and masters for calibration of an indicated dimension are only used at an initial adjustment time.

Abstract: A system for testing a reticle used in semiconductor wafer fabrication is provided. The system includes a reticle that has an opaque metal layer over a translucent substrate. The reticle includes one or more test features containing probe points operable for electrical contact. The system includes a reticle test system that is capable of applying a voltage to the probe points, measuring the resulting current, calculating the corresponding resistance of the test features, and determining the critical dimensions of the test features. The system is also capable of determining defects based on the resistance measurements. The critical dimension information and defect information can then be used to refine the processes used in the fabrication of subsequent reticles.

Abstract: Ramp arrangements and methods in accordance with the present invention can provide the position or velocity of an actuator assembly in a rotating media data storage device while loading or unloading a head connected with the actuator assembly from a disk. One such arrangement includes a conductive ramp electrically coupled to a conductive suspension lift tab such that a closed circuit is formed when the head is unloaded from the disk. As the suspension lift tab slides along the ramp, the resistance of the circuit changes. By measuring multiple positions at multiple times, a head velocity can be determined.

Abstract: A digital eddy current proximity system including a digital impedance measuring device for digitally measuring the proximity probes impedance correlative to displacement motion and position of a metallic target object being monitored. The system further including a cable-length calibration method, an automatic material identification and calibration method, a material insensitive method, an inductive ratio method and advanced sensing characteristics.

Abstract: An orientation sensor especially suitable for use in an underground device is disclosed herein. This orientation sensor includes a sensor housing defining a closed internal chamber, an arrangement of electrically conductive members in a predetermined positional relationship to one another within the chamber and a flowable material contained within the housing chamber and through which electrical connections between the electrically conductive members are made such that a comparison between an electrical property, specifically voltage, of a first combination of conductive members to the corresponding electrical property of a second combination of conductive members can be used to determine a particular orientation parameter, specifically pitch or roll of the sensor.

Abstract: An apparatus for measuring the thickness of thin-film cause electron beams of first and second energies to strike thin-film to be measured that is formed on a silicon substrate, and measures the first substrate current value of current flowing in the substrate when it is struck by an electron beam of a first energy and the second substrate current value of current flowing in the substrate when it is struck by an electron beam of a second energy. The thin-film measuring apparatus obtains reference data indicating a relationship between the film thickness and a reference function having as variables the substrate current for the case of an electron beam of the first energy striking a standard sample and the substrate current for the case of an electron beam of the second energy striking the standard sample, and calculates the thickness of the thin-film under measurement based on the first and second substrate current values, giving consideration to the reference data.

Abstract: A digital eddy current proximity system including a digital impedance measuring device for digitally measuring the proximity probes impedance correlative to displacement motion and position of a metallic target object being monitored. The system further including a cable-length calibration method, an automatic material identification and calibration method, a material insensitive method, an inductive ratio method and advanced sensing characteristics.

Abstract: A digital eddy current proximity system including a digital impedance measuring device for digitally measuring the proximity probes impedance correlative to displacement motion and position of a metallic target object being monitored. The system further including a cable-length calibrations method, an automatic material identification and calibration method, a material insensitive method, an inductive ratio method and advanced sensing characteristics.

Abstract: System for measuring a thickness of a circuit component on a printed circuit board (PCB). The system includes a first circuit, a power plane, a power strip, a calibration strip, a temperature sensor, and a second circuit. The power plane is coupled to the first circuit. The power strip is for providing power to the power plane and is disposed in the PCB connected to the power plane. The power strip has at least two vias. The calibration strip has a predetermined width and is disposed in said PCB. The calibration strip has at least two vias for measuring a voltage drop. The temperature sensor is coupled to the calibration strip and configured to measuring a temperature of the calibration strip. The second circuit is coupled to the temperature sensor and configured to determine the thickness of the calibration strip based on at least the temperature of the calibration strip.

Abstract: Three-dimensional characterization wherein an object interacts capacitively with a resistive medium and the object's orientation, mass distribution and/or distance from the medium is characterized by electrodes distributed linearly around the medium's perimeter. Thus, three-dimensional characteristics are projected into two dimensions and sensed along a single dimension.

Abstract: A highly sensitive, non-contact tank probe to measure surface conductance of thin film structures, and a method for using the same, are described. The tank probe includes inductor (L), capacitor (C) and resistor (R) circuitry that is driven by a signal generator at the probe's resonant frequency. The conductance of a film structure specimen is determined from measuring the signal that is reflected from the tank probe and it respective frequency. Various types of information can be obtained from the tank probe. For instance, information as to film thickness, doping concentration, and the presence of defects can be obtained. In one embodiment of the invention, the tank probe is formed of integrated circuits within a semiconductor substrate. Another aspect of the present invention pertains to a method of using the tank probe system to measure the conductivity of a material specimen.

Abstract: A system for detecting overlapped flat objects in a sequence of flat objects have at least one of their edges exposed for viewing as they pass along a feed path. The system includes a sensor for generating a signal in response to detecting a flat object in the feed path and a camera responsive to the signal for capturing a digital image of the exposed edges of the detected flat object in the feed path. A vision system is coupled to the camera for receiving the digital image. The vision system analyzes at least a portion of the image to determine a pixel density variation along a direction perpendicular to the edges and uses the pixel density variation to output an indication of the number of edges in the image.

Abstract: An orientation sensor especially suitable for use in an underground device is disclosed herein. This orientation sensor includes a sensor housing defining a closed internal chamber, an arrangement of electrically conductive members in a predetermined positional relationship to one another within the chamber and a flowable material contained within the housing chamber and through which electrical connections between the electrically conductive members are made such that a comparison between an electrical property, specifically voltage, of a first combination of conductive members to the corresponding electrical property of a second combination of conductive members can be used to determine a particular orientation parameter, specifically pitch or roll of the sensor.

Abstract: A non-destructive and non-intrusive, user friendly, easy to setup and efficient system and method of determining the gate oxide thickness of an operational MOSFET used in real circuit applications is provided. Additionally, the present invention determines the gate oxide thickness when the operational MOSFET is operating in the inversion mode.

Abstract: A resistance-type liquid level measuring apparatus which suppresses a detection voltage error due to silver sulfide within a permissible range in practical use and enables measurement indication with accuracy, and comprises a resistance-type sensor including a float 9 floating according to a liquid level, an insulating substrate 6 having a plurality of conductor electrodes 4 connected with a resistor 5, and a movable contact interlocked with a movement of the float 9 to come in contact with the conductor electrodes 4 on the insulating substrate 6, in which a material containing silver is used as a material of the conductor electrodes 4 or the movable contact, a voltage dividing resistance 11 is connected with a power source BA in series with the resistor 5, and a voltage of a connection point between the voltage dividing resistance 11 and the resistor 5 is outputted as a signal corresponding to the liquid level, and resistance values of the voltage dividing resistance 11 and the resistor 5 are set so that a v

Abstract: In a first aspect, a method of inspecting objects is provided. The method includes the steps of (1) measuring sheet resistance of a first stack of conducting films deposited on an object, said first stack having a topmost conducting film; (2) depositing a subsequent conducting film on said first stack of conducting films to form a second stack; (3) measuring sheet resistance of said second stack; and (4) calculating sheet resistance of the subsequent conducting film. A thickness of the subsequent conducting film may be determined based on the sheet resistance of the subsequent conducting film. Numerous other aspects are provided.

Abstract: Apparatus for use in measuring and/or monitoring the relative position or displacement of two elements, includes a pair of elongate electrical conductors (10, 11) adapted to be associated with the respective elements, and means (12, 13, 18) for disposing the conductors at a mutual separation such that a detectable quantum tunnelling current may be generated between them on application of an electrical potential difference between the conductors.

Abstract: A digital measuring head in a measuring apparatus measures a work by making a contact element abut to the work. The digital measuring head comprises an arm supported rotatably around a support point arranged on a base; a finger having the contact element at a tip end and mounted to a tip end portion of the arm; and a scale and a read head, one of which is provided at a rear end portion of the arm and the other of which is arranged on the base. Displacement of the contact element which contacts with the work is measured with the scale and the read head. Thereby, the measuring head can perform measurement in a wide range and becomes excellent in the actuation property and the temperature property, and masters for calibration of an indicated dimension are only used at an initial adjustment time.

Abstract: A process for measuring depth of a source and drain of a MOS transistor. The MOS transistor is formed on a semiconductor substrate on which a trench capacitor is formed and a buried strap is formed between the MOS transistor and the trench capacitor. The process includes the following steps. First, resistances of the buried strap at a plurality of different depths are measured. Next, a curve correlating the resistances with the depths is established. Next, slopes of the resistance to the depth for the curve are obtained. Finally, a depth corresponding to a minimum resistance before the slope of the resistance to the depth reaches to zero is obtained.

Abstract: An orientation sensor especially suitable for use in an underground device is disclosed herein. This orientation sensor includes a sensor housing defining a closed internal chamber, an arrangement of electrically conductive members in a predetermined positional relationship to one another within the chamber and a flowable material contained within the housing chamber and through which electrical connections between the electrically conductive members are made such that a comparison between an electrical property, specifically voltage, of a first combination of conductive members to the corresponding electrical property of a second combination of conductive members can be used to determine a particular orientation parameter, specifically pitch or roll of the sensor.

Abstract: A contact-type displacement sensor for detecting a displacement of an object to be detected based on a change in a resistance value includes a resistor having a surface to be slid, a slider which slides on the surface to be slid in a predetermined direction in accordance with a displacement of the object to be detected, and an irregular pattern formed on the surface to be slid and including convex portions and concave portions continuously formed along a direction crossing or perpendicular to a sliding direction of the slider.

Abstract: An electric field is induced from a feature of a reticle, and the field is measured.

Abstract: Disclosed is a wafer containing a semiconductor substrate, at least one metal layer formed over the semiconductor substrate, and at least one electrical sensor embedded at least one of on and in the wafer to facilitate real time monitoring of the metal layer as it progresses through a subtractive metallization process. The system contains a wafer comprising at least one metal layer formed on a semiconductor substrate, at least one electrical sensor in contact with the wafer and operable to detect and transmit electrical activity associated with the wafer, and an electrical measurement station operable to process electrical activity detected and received from the electrical sensor for monitoring a subtractive metallization process in real-time.

Abstract: A material regression sensor and a method of measuring the regression of a material in which the regression sensor includes spaced electrically conductive legs, and electrically conductive sensor element position between the legs and measurement leads electrically connected with the first and second legs.

Abstract: A method of tuning an input signal (S) is described. The method comprises the steps of amplifying the input signal (S) by a gain element (14) having a variable impedance (22) associated therewith and thereby generating an output signal (C), comparing the output signal (C) with a reference voltage (V), tuning the variable impedance (22) such that the impedance is increased if the amplitude of the output signal (C) is smaller than the reference voltage (V), and that the impedance is decreased if the amplitude of the output signal (C) is greater than the reference voltage (V).

Abstract: A displacement detecting device includes a power supply line made of a conductor on a substrate, an earth line made of a conductor on the substrate, a plurality of output lines made of a conductor on the substrate, a resistance formed between the power supply line and the earth line on the substrate, and a brush sliding on the resistance and at least one of the output lines electrically connecting between the resistance and at least one of the output lines, the displacement detecting device generating the output signal from the output lines based on the position of the brush, wherein one of the power supply line and the earth line is disposed between the output lines.

Abstract: A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing.

Abstract: The present invention relates to a semiconductor device, and more particularly, to a test pattern for evaluating a process of silicide film formation. The test pattern in accordance with the present invention includes: a silicon substrate having an active region and a field region; a first pattern composed of a cross resistor pattern of a polycide layer formed on the field region; and a second pattern composed of polycide layer and a silicide layer formed on the active region. The second pattern includes: a pair of polycide patterns composed of a first polycide strip and a second polycide strip extended in parallel, being spaced from each other a predetermined interval on an insulating film formed on the active region; and an active silicide strip formed between the first polycide strip and the second polycide strip.

Abstract: A method for measuring critical dimensions on photomasks, and more specifically to a method for measuring critical dimensions on photomasks using an electrical test structure. The test structure 30 may be comprised of a cross resistor 32 for van der Pauw sheet resistance measurements, a bridge resistor 34, and a split-bridge resistor 36.

Abstract: A method and apparatus for determining the endpoint of a planarization process during chemical mechanical planarization (CMP) and more specifically for determining endpoint of a planarization process for a thin metal film deposited on a wafer's surface and/or a method of altering the plating and deplating of the thin metal film during the planarization process. The apparatus includes one or more probes embedded in a working surface. The probes are in electrical communication with the thin film on the wafer's surface as it is planarized against the working surface. The probes measure the thickness of the thin metal film and/or induce a current in the thin metal film to adjust the plating and deplating that occurs during the planarization process.

Abstract: A method and apparatus for monitoring crack inside piping suitable for high temperature environment including an electrode attachment process for attaching a pair of heat resistant current input-output electrodes to an outer circumferential surface of the piping such that the crack is positioned between electrodes. Measuring intra-crack potential difference by a pair of heat resistant potential difference measuring electrodes attached to outer circumferential surface of the piping and placed between the input output electrodes by supplying alternating current between the input-output electrodes. Crack length is calculated from the measured electric potential difference after correcting the intra-crack electric potential difference as a function pipe temperature and pressure by an intra-crack electrode potential difference correction process.

Abstract: A method for depositing a first metal layer such as tantalum or copper on a patterned semiconductor wafer using a metal sputtering tool that typically includes an electrically biased wafer chuck is disclosed. Initially, a first test wafer is placed on the wafer chuck and a first test layer of materials is deposited on the first test wafer. During the deposition of the first test layer on the first test wafer, the wafer receives the electrical bias at a first level. A second test wafer is then placed on the wafer chuck and a second test layer of material is deposited with the second wafer receiving a second level of electrical bias. The difference in thickness between the first layer and the second layer is then determined. If the difference in thickness is within a predetermined range, the metal sputtering chamber is qualified to deposit a production layer on a production semiconductor wafer.

Abstract: In order to measure a width of a wire a measuring pattern for the width of the wire is prepared. The measuring pattern includes: a first pattern with a first width; a second pattern connected to the first pattern and having a second width wider than the first width; and a third pattern connected to the second pattern and having a third width narrower than the first width. The first pattern, the second pattern and the third pattern are made of same material. The first pattern through a power source is connected to the third pattern. A first pair of probes are disposed on the first pattern and then are connected to a first voltmeter. A distance between the first pair of probes is a first distance wider than the first width. A second pair of probes are disposed on the second pattern and then are connected to a second voltmeter. A distance between the second pair of probes is a second distance wider than the first width.

Abstract: An orientation sensor especially suitable for use in an underground device is disclosed herein. This orientation sensor includes a sensor housing defining a closed internal chamber, an arrangement of electrically conductive members in a predetermined positional relationship to one another within the chamber and a flowable material contained within the housing chamber and through which electrical connections between the electrically conductive members are made such that a comparison between an electrical property, specifically voltage, of a first combination of conductive members to the corresponding electrical property of a second combination of conductive members can be used to determine a particular orientation parameter, specifically pitch or roll of the sensor.

Abstract: A monitor for electrically testing energy beam dose or focus of a layer formed on a substrate by lithographic processing. The monitor comprises a substrate having in a lithographically formed layer an array of electrically conductive elements comprising a plurality of spaced, substantially parallel elements having a length and a width, with the individual elements being electrically connected, and the lengths of the elements being sensitive to dose and focus of an energy beam in lithographically forming the layer. The monitor further includes at least one pad electrically connected to the array to apply current through the array elements. Upon applying a voltage across the array elements, the suitability of dose or focus of the lithographically formed layer may be determined by the resistance of the array. Preferably, ends of the individual elements are aligned along essentially straight lines to form an array edge.

Abstract: A switching element of foil construction is presented, with a triggering layer of first resistive material applied to a first carrier-foil and a sensor layer of a second resistive material applied to a second carrier-foil. The two carrier-foils are arranged a certain distance from each other by means of spacers, in such a way that the triggering layer and the sensor layer are opposite each other and, when the switching element is not operated, are not in contact with each other, whereas, when the switching element is triggered, the triggering layer and the sensor layer are initially in contact with each other at a first point of their surface, and the area of contact increases as the pressure on the switching element is increased.

Abstract: A method and system for identifying thicknesses of inspection samples, such as semiconductor wafers is presented. The method and system includes a probe housing, comprising an eddy current sense coil and a linear motion controller, and a computer that controls the linear motion controller and the eddy current sense coil. The computer may be configured to identify a thickness of the inspection sample by a method comprising the generation of a natural intercepting curve based on resistance and reactance measurements of at least two data points. Then, a plurality of corresponding resistance and reactance measurements of a location on the inspection sample is obtained with the eddy current sensor, where the eddy current sensor makes a first measurement at a first distance from the inspection sample, and makes each of the remaining plurality of measurements at a distance that is incrementally further away from the inspection surface.

Abstract: The present invention provides a method and apparatus for determining when an actual width of a resistor in an integrated circuit varies from a design width for that resistor due to process variations. The method and apparatus may be used to determine an actual amount of the process width variation. This amount may be used to effectively match resistors in an integrated circuit that do not have identical design width. The determination of process width variation in an integrated circuit may be used to match the bias resistor of a integrated current steering digital to analog converter to the converter's output resistors.

Abstract: In one embodiment, a high-resolution measurement apparatus and method determine the position and motion of an object such as a human hand relative to a sensor array. Capacitance transferred to the array by the object within a sensor field produces minute phase changes in a fixed-frequency reference signal applied to the several elements of the array. The phase changes are measured by first heterodyning the phase-shifted reference signal with a second reference signal to obtain a low frequency intermediate signal, and then employing a phaselocked loop to multiply the phase information in the intermediate signal by orders of magnitude, thereby permitting the use of conventional methods to measure the resulting greatly magnified phase changes. Other embodiments provide direct digital measurement of unknown electrical properties, such as capacitance, inductance, and resistance.

Abstract: The present invention provides a method and apparatus for determining when an actual width of a resistor in an integrated circuit varies from a design width for that resistor due to process variations. The method and apparatus may be used to determine an actual amount of the process width variation. This amount may be used to effectively match resistors in an integrated circuit that do not have identical design width. The determination of process width variation in an integrated circuit may be used to match the bias resistor of a integrated current steering digital to analog converter to the converter's output resistors.

Abstract: A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing.

Abstract: A test pattern for use in measuring thickness of insulating layer comprising a wiring pattern provided in an insulating layer and a dummy pattern provided in the insulating layer. The wiring pattern has a electrical resistant value depending on the thickness of the insulating layer. The dummy pattern is provided so as to be adjacent to the wiring layer. The dummy pattern allows the thickness of the insulating layer thereon to be directly measured. By using the test pattern, characteristic chart showing a relationship between the electrical resistance value and the thickness of the insulating layer.

Abstract: A probe for determining a surface characteristic of an object includes a substrate, a plurality of cantilevers each having a distal end coupled to the substrate, and a plurality of probe tips each coupled to a proximal end of a respective one of the cantilevers for contacting a surface of the object. Such probes can be used to study properties of objects, such as layers of semiconductor devices. Electrical properties of the surface of the object, such as, for example, surface resistivity, can be determined using probes with conductive probe tips. Some probes include a substrate divided lengthwise into a first section and a second section with the first section being doped with an n-type material and the second section being doped with a p-type material. Other probes include conductive material disposed on the substrate and, optionally, on the cantilevers and/or probe tips to form individual conductive paths to the probe tips.

Abstract: There is disclosed an internal sizing apparatus comprising a pneumatically activated probe that moves axially within a shoe and non-destructively measures the interior dimensions of the shoe. A linear pneumatic actuator is mounted between a heel piece and a probe. A linear potentiometer is mounted above the actuator and also connects to the probe. The apparatus is inserted into a shoe with the heel piece seated against the interior heel portion of the shoe. A computer system controlling the actuator extends the probe linearly into the shoe until the probe contacts the toe portion of the shoe. The potentiometer then measures the linear distance traveled by the probe and thus determines the internal linear dimension of the shoe. Depending on the type of probe, three-dimensional internal measurements of the shoe can also be quantified.

Abstract: A method and apparatus for measuring sheet resistance and thickness of thin films and substrates. A four-point probe assembly engages the surface of a film on a substrate, and the thickness of the substrate is determined from the point of contact between the probes and film. A measuring apparatus then outputs a voltage waveform which applies a voltage to probes of the probe assembly. An inverter inverts the voltage and provides the inverted voltage on another probe of the probe assembly, thus inducing a current in these probes of the four point probe and through the surface of the film. Two other probes measure a voltage in the film created by the current. The voltages on the current probes provide a voltage close to zero at the other probes, thus allowing these other probes to measure voltages with greater precision. The current created by the voltage waveform and the voltage created across the inner probes are measured for each voltage level of the waveform.

Abstract: A thin-film depositing apparatus of the present invention deposits a sputtered film on a substrate in a sputtering chamber, and removes the substrate having the sputtered film deposited thereon from the sputtering chamber via a load-lock chamber by a robot arm. As a system for controlling the sheet resistance of the sputtered film deposited on the substrate, a measuring device using an eddy current method is mounted in the proximity of a substrate outlet of the load-lock chamber and measures the sheet resistance of the sputtered film of the substrate removed from the substrate outlet. With this structure, it is possible to provide a thin-film depositing apparatus which stably measures the sheet resistance of a thin film deposited on a substrate and performs feedback of the measurement result to control the film deposition conditions so that a thin film to be deposited on a subsequent substrate has a desired thickness.

Abstract: A linear position sensor has first and second output signal generators each of which outputs an output signal in accordance with the position of a detection object. As the detection object moves from an initial position, the output signal of the first output signal generator linearly increases from an output value corresponding to the initial position of the detection object. The output signal of the second output signal generator linearly increases from an output value that is greater than the output value corresponding to the initial position of the detection object. After reaching a maximum value, the output signal of the second output signal generator remains at the maximum value when the detection object further moves to a maximum displacement position.