Abstract: An electrical resistor is made by providing a sacrificial layer and conductive pads disposed on a first surface of the sacrificial layer. An electrically resistive material is deposited over the pads and on the first surface of the sacrificial layer to form at least one unit including the resistive material and the pads. At least part of the sacrificial layer is then removed so as to expose one or more of the pads.

Abstract: Improved method steps for terminating multilayer electronic components are disclosed. Monolithic components are formed with plated terminations whereby the need for typical thick-film termination stripes is eliminated or greatly simplified. Such termination technology eliminates many typical termination problems and enables a higher number of terminations with finer pitch, which may be especially beneficial on smaller electronic components. Electrode and dielectric layers are provided in an interleaved arrangement and selected portions of the electrode layers are exposed. Electrically isolated anchor tabs may optionally be provided and exposed in some embodiments. Termination material is then plated to the exposed portions of the electrode layers until exposed portions of selected such portions thereof are connected. A variety of different plating techniques and termination materials may be employed in the formation of the subject self-determining plated terminations.

Abstract: A heating element that can be incorporated into a molded foam article closely adjacent to the outer cover sheet without showing any evidence that a heating element is encapsulated within the foam portion of the article and provides essentially the same relatively softness and “feel” that would be obtained if the heating element was not part of the article.

Abstract: The invention relates to a method of making a chip resistor using a material substrate for which are set a plurality of first cutting lines extending in a first direction and a plurality of second cutting lines extending in a second direction perpendicular to the first direction. The method includes an upper electrode forming step A for forming a thick upper conductor layer on the upper surface of the substrate by printing and baking a metal organic paste, a lower electrode forming step B for forming a thick lower conductor layer on the lower surface of the substrate by printing and baking metal organic paste, and a resistor element forming step C for forming a thin resistor layer by depositing a resistor material on the upper surface of the substrate. Preferably, the upper and the lower surfaces of the material substrate are flat.

Abstract: The present invention discloses a method for preparing a conductive polymeric composite material having carbon black utilized to a structure for composite materials of a positive temperature coefficient thermistor. The method first provides a metal laminated material comprising a top metal layer and a bottom metal layer, an insulating layer between the top and the bottom metal layer, and a conducting through hole disposed between the top metal layer and the bottom metal layer. A composite electroplating process is then performed to form an composite electroplating layer on the surface of the top metal layer, wherein the composite electroplating layer is a continuous porous structure with a secondary aggregation of carbon black and electroplated metal.

Abstract: The invention relates to a strain-sensitive resistor, comprising a resistance layer arranged on a support element and an electromechanical transducer produced with this resistor. An increase in the electrical measured signal picked off across the resistor is achieved in a simple way by the support element (1) having a recess (7) on its surface (9) which, when the support element (1) is subjected to mechanical stress in at least one area of the surface (9) of the support element (1) in which the resistance layer (4) is positioned, produces a ratio between the two main strain directions (L, T) of the resistance layer (4) which differs in magnitude.

Abstract: A metal resistor and a method for manufacturing the resistor are provided. A first insulation film is formed on a substrate, a photosensitive film is applied on the insulation film, and an insulation film pattern is formed by patterning the insulation film. After a metal thin film is formed among the insulation film pattern and on the photosensitive film, with removing the photo-sensitive film is a metal thin film pattern formed among the insulation film pattern. On the metal thin film pattern and the insulation film pattern is a second insulation film formed and at the pad region of the metal thin film pattern is a lead wire connected, after that, a metal thin film resistor is manufactured with forming a preservation film on and around the lead wire.

Abstract: An inexpensive fine resistor which do not require dimensional classifications of discrete substrates, eliminating a process of replacing a mask according to a dimensional ranking of each discrete substrate as in the prior art. The resistor includes discrete substrate made into pieces by dividing an insulated substrate sheet along a first slit dividing portion and a second dividing portion perpendicular to the first dividing portion; top electrode layer formed on a top face of discrete substrate; resistor layer formed such that a part of resistor layer overlaps top electrode layer; protective layers formed so as to cover resistor layer; side electrode layer formed on a side face of discrete substrate such that side electrode layer is electrically coupled to top electrode layer.

Abstract: A method of fabricating a colossal magneto-resistive detector using a thin film transfer method includes the use of a perovskite oxide material as a substrate, and a rock salt structure material as a buffer layer, template layer, and release layer. Advantages associated with the method include not only the ability to produce a detector of the requisite film quality, but one which satisfies the temperature coefficient of resistance and fabrication temperature constraints. In addition, when employed as either the substrate or the buffer layer, template layer, and release layer, after bonding the rock salt structure material can be easily removed using water, and the excess rock salt structure material/water solution can then be removed with known techniques.

Abstract: A surface mount resistor includes an elongated piece of resistive material having strips of conductive material attached to its opposite ends. The strips of conductive material are separated to create an exposed central portion of the resistive material therebetween. According to the method the resistive strip is attached to a single co extensive strip of conductive material and a central portion of the conductive material is removed to create the exposed central portion of the resistive strip.

Abstract: The invention is a system for controlling the position of a movable member moved by a prime mover by monitoring the position of the movable member; generating position information based upon this monitoring; and controlling the prime mover based upon the position information by providing a counter force to the movable member substantially equal to an opposing force opposing the movement of the movable member. The invention may include a movable member, such as a ram used for fastening a terminal to a wire; a spring; a DC planetary gear motor for providing a force to the movable member opposing the spring; a position detector, such as an linear voltage displacement transducer, to detect the position of the movable member and generate position information; and a controller, which may include a logic board or microprocessor and memory, for controlling the force from the motor in response to the position information.

Abstract: A high precision power resistor having the improved property of reduced resistance change due to power is disclosed. The resistor includes a substrate having first and second flat surfaces and having a shape and a composition; a resistive foil having a low TCR of about 0.1 to about 1 ppm/° C. and a thickness of about 0.03 mils to about 0.7 mils cemented to one of the flat surfaces with a cement, the resistive foil having a pattern to produce a desired resistance value, the substrate having a modulus of elasticity of about 10×106 psi to about 100×106 psi and a thickness of about 0.5 mils to about 200 mils, the resistive foil, pattern, type and thickness of cement, and substrate being selected to provide a cumulative effect of reduction of resistance change due to power. The present invention also provides for a method of producing a high precision power resistor.

Abstract: A bubble-jet type ink-jet printhead and manufacturing method thereof including a substrate integrally having an ink supply manifold, an ink chamber, and an ink channel; a nozzle plate having a nozzle on the substrate; a heater centered around the nozzle and an electrode for applying current to the heater on the nozzle plate; and an adiabatic layer on the heater for preventing heat generated by the heater from being conducted upward from the heater. Alternatively, a bubble-jet type ink-jet printhead may be formed on a silicon-on-insulator (SOI) wafer having a first substrate, an oxide layer, and a second substrate stacked thereon and include an adiabatic barrier on the second substrate. In the bubble-jet type ink-jet printhead and manufacturing method thereof, the adiabatic layer or the adiabatic barrier is provided to transmit most of the heat generated by the heater to ink under the heater, thereby increasing energy efficiency.

Abstract: The invention is directed to a method to embed a thick film resistor composition into a printed wiring board comprising the steps of applying a reinforcing composition onto a resistor composition disposed on a metallic substrate forming an assembly wherein the resistor composition is at least partially coated with the reinforcing composition; processing the assembly; and applying the assembly onto at least one side of an organic substrate forming a component wherein the organic substrate is at least partially coated with an adhesive layer and wherein the reinforcing composition side of the assembly is embedded into the adhesive layer. The reinforcing composition allows laser trimming of the fired resistor and also eliminates cracking during lamination steps of the invention.

Abstract: The invention provides for a method of manufacturing a stacked power chip resistor. The method includes adhering a first chip resistor to a second chip resistor with a glass encapsulant, connecting a first terminal of the first chip resistor to a first terminal of the second chip resistor with the first metal barrier, and connecting a second terminal on the first chip resistor to a second terminal of the second chip resistor with a second metal barrier.

Abstract: A method of producing a strain sensitive resistor includes matching an area of a film insulating layer to a shape of a recess in a surface of a support element. The film insulating area is applied to the support element so that the area of the film matching the shape of the recess is congruent with the shape of the recess. A resistive layer comprising strain-sensitive resistors is applied to the film insulating layer and the film insulating layer and the resistive layer are applied to heat treatment.

Abstract: An electrical resistor is made by providing a sacrificial layer and conductive pads disposed on a first surface of the sacrificial layer. An electrically resistive material is deposited over the pads and on the first surface of the sacrificial layer to form at least one unit including the resistive material and the pads. At least part of the sacrificial layer is then removed so as to expose one or more of the pads.

Abstract: A power adapter is shown for use on injection molding runner nozzles. The power adapter provides for quick and easy installation (and removal) of thick film resistance heaters on the runner nozzles, without the need for rewiring. The power adapter comprises a series of rings that allow insertion of the terminal end of the heater, which is then rotated into a locked position. One of the rings contains contacts which are at least semi-permanently wired to a power source. To facilitate the power adapter, a novel method terminating the heating element is used. A noble-metal-based bonding agent (such a silver-base ink) is applied to the heating element and/or terminal plate. The terminal plate is then affixed to the heating element and the bonding agent is fired.

Abstract: A surface mount resistor includes an elongated piece of resistive material having strips of conductive material attached to its opposite ends. The strips of conductive material are separated to create an exposed central portion of the resistive material therebetween. According to the method the resistive strip is attached to a single co extensive strip of conductive material and a central portion of the conductive material is removed to create the exposed central portion of the resistive strip.

Abstract: A temperature sensor including a thermosensitive element and a ceramic body having a hollow section which surrounds the thermosensitive element airtightly. The thermosensitive element is formed on a heat-sensing surface side of the ceramic body having the hollow section. The hollow section is formed at a position which is shifted to the heat-sensing surface side with respect to the center of the temperature sensor. The ceramic body includes a heat-sensing surface side ceramic layer (1) having the thermosensitive element (4) disposed thereon, a spacer ceramic layer (3) having an aperture, and a substrate ceramic layer (2) serving as a substrate.

Abstract: A heated element assembly and method of manufacturing heated element assemblies is provided. The heated element assembly including a first and second molded sections shaped to mate with each other is provided. A resistance heating element is secured between the first and second molded sections by an interference fit. The resistance heating element includes a piercable supporting substrate and a resistance wire sewn thereon. The resistance wire is disposed in a predetermined circuit path which is substantially encompassed by the first and second molded sections. The resistance heating element is easily fixed in a position between the first and second molded sections and is capable of providing heat on vertical, horizontal and contoured surfaces.

Abstract: A high precision power resistor having the improved property of reduced resistance change due to power is disclosed. The resistor includes a substrate having first and second flat surfaces and having a shape and a composition; a resistive foil having a low TCR of about 0.1 to about 1 ppm/° C. and a thickness of about 0.03 mils to about 0.7 mils cemented to one of the flat surfaces with a cement, the resistive foil having a pattern to produce a desired resistance value, the substrate having a modulus of elasticity of about 10×106 psi to about 100×106 psi and a thickness of about 0.5 mils to about 200 mils, the resistive foil, pattern, type and thickness of cement, and substrate being selected to provide a cumulative effect of reduction of resistance change due to power. The present invention also provides for a method of producing a high precision power resistor.

Abstract: A method of making a low-cost metal diaphragm sensor that integrates both pressure and temperature sensing in a single sensor assembly utilizes thick-film processing to form a circuit including stress and temperature sensitive elements on the outboard or exposed surface of a thin metal diaphragm separating the circuit from a pressurized fluid. Only a thin layer of dielectric separates the stress and temperature sensitive elements from the diaphragm surface. The stress sensitive elements respond to mechanical stressing of the diaphragm due to the presence of the pressurized fluid, while the temperature sensitive element responds to the temperature of the pressurized fluid. The thermal capacity of the fluid greatly exceeds that of the diaphragm, so that the temperature responsive characteristic of the temperature sensitive element accurately reflects the temperature of the pressurized fluid.

Abstract: According to the method the resistive strip is attached to a single co extensive strip of conductive material and a central portion of the conductive material is removed to create the exposed central portion of the resistive strip.

Abstract: An inkjet printing device employs an inkjet printhead with a plurality of drop generators to eject drops of ink. Each drop generator includes a planar heater resistor, comprising three segments. Two of the segments are disposed on either side of the third segment and provide a reduced thermal loss for the third segment. This reduced thermal loss and other features cause a controlled nucleation point to occur over the third segment even though the two segments on either side will create ink vapor bubbles of variable size depending upon the applied energy.

Abstract: A method of fabricating a colossal magneto-resistive detector using a thin film transfer method includes the use of a rock salt structure material as a substrate. In a second embodiment, the method includes the use of a perovskite oxide material as the substrate, and the rock salt structure material as a buffer layer, template layer, and release layer. Advantages associated with the method include not only the ability to produce a detector of the requisite film quality, but one which satisfies the temperature coefficient of resistance and fabrication temperature constraints. In addition, when employed as either the substrate or the buffer layer, template layer, and release layer, after bonding the rock salt structure material can be easily removed using water, and the excess rock salt structure material/water solution can then be removed with known techniques.

Abstract: A load cell is constructed with several strain gauges. Each of the strain gauges are formed with a meandering conductive portion on a substrate or base member. Portions of the meandering conductive layer defines a predetermined tab ratio. The base member is formed with a predetermined amount of filler and the tab ratio is pre-determined such that the creep characteristic of the strain gauge is substantially zero in a load cell having a generally low rated load.

Abstract: A chip thermistor is produced by first preparing green sheets containing a NTC thermistor ceramic material and an organic binder, then applying a resistor paste on one or more of these green sheets and an inner electrode paste on some others, and forming a layered structure free of PTC materials by stacking and compressing together specified numbers of these green sheets. The layered structure is then subjected to a firing process and outer electrodes are formed on oppositely facing pair of outer end surfaces of the layered structure. The chip thermistor thus produced has a main body of a thermistor ceramic material having a specified resistance-temperature characteristic, a pair of outer electrodes on its end surfaces, at least one resistor having resistance greater than 1&OHgr;, and at least one pair of inner electrodes opposite each other and separated from each other with the thermistor ceramic material in between.

Abstract: A surface-mount positive temperature coefficient thermistor includes a disk-shaped positive temperature coefficient thermistor element having electrodes provided on opposing main surfaces thereof, an insulating case having an inner space with the thermistor element inserted therein, and a pair of metal terminals arranged to make electrical contact with the respective main surface electrodes of the thermistor element, and to sandwich therebetween the thermistor element. The insulating case includes a pair of main surfaces that are substantially parallel to the main surfaces of the thermistor element, a pair of opening side surfaces each having an opening, and a pair of end surfaces each having a terminal insertion hole provided therein. One end of each of the pair of metal terminals is inserted from the respective terminal insertion holes into the inner space, and the metal terminals press-hold the thermistor element so as to sandwich the thermistor element therebetween.

Abstract: An electrical device which comprises first and second laminar electrodes and a laminar PTC resistive element sandwiched between them, the device comprising: (a) a main portion which comprises a main part of the first electrode, a main part of the second electrode, and a main part of the resistive element; and (b) a first connection leg which extends away from the main portion and which comprises a first leg part of the first electrode which is integral with the main part of the first electrode, and a first leg part of the resistive element which is integral with the main part of the resistive element. Such devices can be secured to circuit boards in a variety of ways, and to elastically deformed terminals. Preferably preferred devices contain two laminar electrodes, with a PTC element between them, and a cross-conductor which passes through the thickness of the device and contacts one only of the two electrodes.

Abstract: A method for efficiently producing low resistance electrical contacts between stainless steel and conductive layers in integrated lead suspensions and components. The method includes applying an amount of current for a period of time which is effective to reduce the resistance to a desired level. One embodiment of the invention includes applying a 100 mA current for 16 msec to a contact formed by thermosetting conductive epoxy. Resistance levels below 1 ohm can be achieved.

Abstract: A process for manufacturing a composite polymeric circuit protection device in which a polymeric assembly is provided and is then subdivided into individual devices. The assembly is made by providing first and second laminates, each of which includes a laminar polymer element having at least one conductive surface, providing a pattern on at least one of the conductive surfaces on one laminate, securing the laminates in a stack in a desired configuration, at least one conductive surface of at least one of the laminates forming an external conductive surface of the stack, and making a plurality of electrical connections between a conductive surface of the first laminate and a conductive surface of the second laminate. The laminar polymer elements may be PTC conductive polymer compositions, so that the individual devices made by the process exhibit PTC behavior.

Abstract: A heatable vehicle window (e.g., windshield, sidelite or backlite) includes a multi-layer coating formed on a substrate. The multi-layer coating includes at least one dielectric layer and at least one conductive layer. A pair of bus bars are deposited on the substrate over the coating, so that at least the dielectric layer is provided between the bus bars and the conductive layer(s). In order to create an electrical connection between the bus bars and the conductive layer(s) of the coating, the bus bars and/or coating is/are heated to a temperature sufficient to permit the bus bars to reach molten or semi-molten form. Portions of bus bar material then flow down through at least the dielectric layer of the coating (i.e., forming a contact hole in the coating) so as to contact the coating's conductive layer(s). After cooling of the newly formed bus bars, the window may be selectively heated by passing current through the conductive layer(s) via the bus bars.

Abstract: A method of manufacturing a resistor foil, comprised of a copper layer having a first side and a second side. A tiecoat metal layer having a thickness of between 5 Å and 70 Å is disposed on the first side of the copper layer. A first layer of a first resistor metal having a thickness of between 100 Å and 500 Å is disposed on the tiecoat metal layer, and a second layer of a second resistor metal having a thickness of between 100 Å and 500 Å is disposed on the first layer of the first resistor metal. The first resistor metal has a resistance different from the second resistor metal.

Abstract: The invention relates to a method of making a chip resistor using a material substrate for which are set a plurality of first cutting lines extending in a first direction and a plurality of second cutting lines extending in a second direction perpendicular to the first direction. The method includes an upper electrode forming step A for forming a thick upper conductor layer on the upper surface of the substrate by printing and baking a metal organic paste, a lower electrode forming step B for forming a thick lower conductor layer on the lower surface of the substrate by printing and baking metal organic paste, and a resistor element forming step C for forming a thin resistor layer by depositing a resistor material on the upper surface of the substrate. Preferably, the upper and the lower surfaces of the material substrate are flat.

Abstract: The invention is directed to a method to embed a thick film resistor composition into a printed wiring board comprising the steps of applying a reinforcing composition onto a resistor composition disposed on a metallic substrate forming an assembly wherein the resistor composition is at least partially coated with the reinforcing composition; processing the assembly; and applying the assembly onto at least one side of an organic substrate forming a component wherein the organic substrate is at least partially coated with an adhesive layer and wherein the reinforcing composition side of the assembly is embedded into the adhesive layer. The reinforcing composition allows laser trimming of the fired resistor and also eliminates cracking during lamination steps of the invention.

Abstract: Disclosed are a PCB with buried or embedded resistors and a method for manufacturing the same. The PCB comprises: a resinous, electrically insulating substrate; a circuit pattern formed on the substrate; at least a pair of spaced resistor terminations, formed in a certain pattern on the substrate, each comprising a metal pad covered with a conductive protective layer; a thin-film resistor formed between the resistor terminations with electrical connection thereto; and an over-coating layer formed of one-part ink, covering the resistor and the resistor terminations. To be provided with a desired resistance, optionally, the resistor may be grooved by laser trimming. The PCB can have a desired resistor resistance which is uniform without being affected by environmental factors.

Abstract: A method and system for fabricating electrical heating devices employing positive temperature coefficient (PTC) thermistor as heating elements which includes: assembling the heating devices with PTC thermistor heating elements preselected according to electrical resistance, applying pressure across the interface between the PTC heating elements and the radiator plates of the heating devices during their assembly, and exposing the heating devices for extended periods of time to both ambient and operational temperatures. The method of fabrication further includes continuously monitoring the electrical resistance of the heating devices and holding their electrical resistance stable by adjusting the pressure applied across the interface between the PTC heating elements and the radiator plates.

Abstract: A method of manufacturing a thermal head comprises forming a heating resistor on an insulating substrate and forming a wiring electrode on the heating resistor so that a heating portion of the wiring electrode is disposed around the heating resistor. An inorganic masking agent is disposed on a given portion of the wiring electrode, and a protective film is formed over the heating resistor, the wiring electrode and the inorganic masking agent. The protective film is then removed from the given portion of the wiring electrode together with the inorganic masking agent to selectively form the protective film on the heating resistor and on the heating portion of the wiring electrode.

Abstract: A method of forming trimmable resistors, resistor ray be embedded into a substrate. A portion of the resistor may be exposed, by segmenting the substrate, so that the resistor may be trimmed to a desired resistance level. Alternatively, a portion of a resistor may be embedded into a substrate, with another portion of the resistor being disposed on the outer surface of the substrate. The portion of the resistor on the outer surface may be trimmed to adjust the resistance of the resistor to a desired level.

Abstract: A method of manufacturing a printed circuit board with a polymer thick-film (PTF) resistor whose dimensions can be defined with improved precision by providing a circuit board construction having a planar surface where the resistor is to be deposited. To achieve the desired board construction, the interconnect for the resistor is pattern plated using a permanent photodielectric layer as a plating mask instead of a sacrificial plating resist. The interconnect can be patterned before or after the PTF resistor ink is printed. The x and z dimensions (width and thickness, respectively) of the resistor are determined by the deposition process, while the y dimension (electrical length) is accurately determined by copper terminations.

Abstract: A first rotor and a second rotor are prepared. The first rotor has a resistor and inner-peripheral and outer-peripheral electrodes respectively connected to end portions of this resistor. The second rotor has a resistor and inner-peripheral and outer-peripheral electrodes symmetrical with those of the first rotor, provided at a position corresponding to that obtained by rotating the first rotor about the axis of the first rotor by an angle of 180° with respect to the first rotor. A variable resistor selectively uses either one of the first rotor and second rotor. This makes it possible to provide a variable resistor which requires few parts. Also, this makes it possible to reduce the kinds of bending operations that must be performed on the terminals.

Abstract: A surge arrester includes an electrically insulating arrester housing and a surge arresting block housed within the electrically insulating arrester housing. The surge arresting block is arranged to provide support for the surge arrester without the use of a support member. The surge arresting block may be a single surge arresting block having a voltage rating of at least 9 KV. The surge arresting block may have threads formed integrally therewith.

Abstract: A surface mount resistor includes an elongated piece of resistive material having strips of conductive material attached to its opposite ends. The strips of conductive material are separated to create an exposed central portion of the resistive material therebetween. According to the method the resistive strip is attached to a single co extensive strip of conductive material and a central portion of the conductive material is removed to create the exposed central portion of the resistive strip.

Abstract: A surface mount resistor includes an elongated piece of resistive material having strips of conductive material attached to its opposite ends. The strips of conductive material are separated to create an exposed central portion of the resistive material therebetween. According to the method the resistive strip is attached to a single co extensive strip of conductive material and a central portion of the conductive material is removed to create the exposed central portion of the resistive strip.

Abstract: A method of making a small chip resistor properly and efficiently is provided. This method makes chip resistors each of which comprises a unit substrate which is rectangular as viewed in plan and has a predetermined thickness, a resistor element provided on an upper surface of the substrate, and electrodes provided at opposite ends of the unit substrate.

Abstract: The invention relates to a chip resistor which is used as a circuit part for various electric apparatuses. The object of the invention is to realize a low resistance and a low TCR, and also high accuracy and high reliability. In order to achieve the object, a chip resistor is configured so as to have: a substrate; a resistance layer which is formed on at least one face of the substrate and which is made of a copper nickel alloy; upper-face electrode layers which make surface contact with the upper faces of both the end portions of the resistance layer; and end-face electrodes which are formed so as to cover the upper-face electrode layers. Since the bonding between the resistance layer and the upper-face electrode layers is conducted by metal-to-metal bonding, particularly, impurities which may affect the Properties do not exist in the interface. As a result, it is possible to realize a chip resistor which is excellent in heat resistance, and which has a low resistance and a low TCR.

Abstract: A piezoresistor having a base substrate with a quantum well structure formed on the base substrate. The quantum well structure includes at least one quantum well layer bounded by barrier layers. The barrier layers are formed from a material having a larger bandgap than the at least one quantum well layer.

Abstract: A method of manufacturing a printed circuit board with a polymer thick-film (PTF) resistor whose dimensions can be defined with improved precision by providing a circuit board construction having a planar surface where the resistor is to be deposited. To achieve the desired board construction, the interconnect for the resistor is pattern plated using a permanent photodielectric layer as a plating mask instead of a sacrificial plating resist. The interconnect can be patterned before or after the PTF resistor ink is printed. The x and z dimensions (width and thickness, respectively) of the resistor are determined by the deposition process, while the y dimension (electrical length) is accurately determined by copper terminations.

Abstract: An A/F sensor generates a current signal corresponding to an air-fuel ratio in response to a voltage applied by a bias control circuit. After a sensor current is received as a voltage signal via a voltage follower, it is outputted to an A/D converter having a predetermined input voltage range, 0 to 5V. A sensor current detection circuit has a plurality of current detection resistors. In order to variably set the resistance value by the sensor current detection circuit, a switch circuit is switched in accordance with the sensor current depending on whether the A/F value to be detected is in the zone near the stoichiometric ratio or in other air-fuel ratio zones.