Abstract: The present invention is directed to a method of making a transformer having a stacked core, which includes top and bottom yokes and first and second outer legs. The core also includes an inner leg that is formed from a pair of stacked plates, which abut each along a seam that extends in the longitudinal direction of the inner leg. Each of the upper and lower yokes may be formed from a single stack of plates, or a plurality of stacks of plates. Each of the inner and outer legs may also be formed from a single stack of plates, or a plurality of stacks of plates. The cross-section of the core may be rectangular or cruciform.

Abstract: An electromagnetic noise absorber to be attached around an electric cable to attenuate noise transmitted through the electric cable. The electromagnetic noise absorber comprises a strip-like base material and a plurality of ferrite pieces fixed to the strip-like base material. The plurality of ferrite pieces are formed by fixing a sheeted ferrite sintered body to the strip-like base material, and subsequently splitting the sheeted ferrite sintered body along split lines oblique with respect to a longitudinal direction of the strip-like base material. The electromagnetic noise absorber is wound around a circumference of the electric cable such that the split lines are parallel to an axial direction of the electric cable, thereby being attached in a spiral manner around the circumference of the electric cable.

Abstract: A power converter employing a magnetic device including a magnetic core and first and second tapped windings. Each winding of the magnetic device has first and second winding sections, respectively, coupled to the magnetic core, wherein the first and second winding sections are formed from a formed and folded planar conductive sheet. The magnetic core includes a common leg, a plurality of outer legs, and a top plate. The first and second winding sections are constructed with a formed and folded planar conductive sheet formed with structures usable as pins in a through-hole, surface-mount, or combined printed wiring board assembly process. The outer legs at either end of the magnetic core are positioned back from magnetic core ends, and the magnetic core is formed with a stepped structure to accommodate winding pins in a surface-mount printed wiring board assembly process.

Abstract: An inductive element having a gap and a fabrication method thereof are disclosed. The fabrication method is for fabricating an inductive element having a first core body, a second core body and a gap, and includes: coating an adhesive on a gap-facing side of the first core body and/or the second core body; providing a linear spacer and installing the linear spacer between the first core body and the second core body; and combining the side of the first core body where the adhesive is coated with the side of the second core body where the adhesive is coated, allowing the linear spacer to form the gap when the first core body is combined with the second core body. Thereby, the linear spacer establishes the size of the gap of the inductive element and improves the adhesion of the first core body to the second core body.

Abstract: A composite transformer includes a bobbin assembly, a magnetic core covering element and a magnetic core assembly. The bobbin assembly includes at least a first connecting part and a first channel, wherein at least a primary winding coil and at least a secondary winding coil are wound around the bobbin assembly. The magnetic core covering element includes a second channel and at least a second connecting part. The at least a second connecting part of the magnetic core covering element is coupled with the at least a first connecting part of the bobbin assembly, so that the magnetic core covering element is combined with the bobbin assembly. The magnetic core assembly is partially embedded into the first channel of the bobbin assembly and the second channel of the magnetic core covering element.

Abstract: A transformer includes primary and secondary windings coupled electromagnetically to each other and wounded respectively around primary and secondary winding portions of a bobbin unit, and a core unit mounted to the bobbin unit and including first and second core parts that form a magnetic circuit path. The first core part includes insertion and extension segments extending from a connecting segment. The second core part includes insertion and extension segments, and an adjusting segment extending from a connecting segment toward the first core part. The extension segments of the first and second core parts contact each other. The insertion segments of the first and second core parts extend respectively through the primary and secondary winding portions to contact each other.

Abstract: There is provided a ferrite core assembly comprising a plurality of ferrite elements and a plurality of spacer elements, wherein each spacer element comprises formations for engaging with two ferrite elements, thereby to locate the ferrite elements with respect to each other. Various embodiments of the spacer element are described with one spacer element formed with a spigot extending from each face that adjoins a ferrite element. The spacer element can include gripping protrusions, to grip an external surface of a ferrite rod or ferrite bead, or an internal surface of a ferrite bead. There is also provided broadband and cable network equipment incorporating a ferrite core assembly comprising a plurality of ferrite elements and a plurality of spacer elements, wherein each spacer element comprises formations for engaging with two ferrite elements, thereby to locate the ferrite elements with respect to each other.

Abstract: A subsea data and power transmission apparatus includes primary and secondary open magnetic circuits with coils for wireless data and power transfer between a drilling tool and a drilling rig. The primary magnetic circuit is U-shaped and the secondary is O-shaped. Both magnetic systems are electrically insulated. The electrical signal and power are transferred from one magnetic circuit to another through an air or water gap between the magnetic circuits. The U-shaped and O-shaped magnetic circuits allow communication and power transfer remotely with no mechanical or electrical connectors.

Abstract: A high-voltage isolation transformer utilizing balun cores for transferring an alternating current signal from a first circuit to an output circuit, and a high voltage generator, such as a Cockcroft-Walton multiplier to apply a high direct current voltage bias with a high degree of voltage isolation between the first circuit and the output circuit. Multiple balun core transformers can be used in order to reduce the voltage rise between each individual transformer.

Abstract: A method for producing a winding, particularly for electrical transformer from a cylindrical tubular metal element of polygonal cross-section, includes steps of machining, in a first series of passes, a first series of cuts substantially parallel to one another through all of the sides of the tubular element with the exception of a last one of said sides, and machining, in a second series of passes, a second series of cuts in said last one of said sides in order to ensure that junctions of the first series of cuts open out in the sides adjacent to the second series of cuts, so that the first and second series of cuts are continuous with respect to one another and constitute a single groove of helicoidal shape.

Abstract: A ferrite sheet includes a ferrite sintered body capable of being in direct and sufficiently close contact with a signal cable and has good noise removal properties. The ferrite sheet includes a flexible sheet having a foldable portion, a plurality of ferrite sintered bodies located in a region other than the foldable portion on the flexible sheet, an elastic body arranged around the ferrite sintered bodies on the flexible sheet, and an adhesive layer arranged on the elastic body such that the elastic body is bonded to itself when the flexible sheet is bent along the foldable portion.

Abstract: An inductor array that includes a plurality of inductors where adjacent inductors share a core piece and thus a flux path to reduce the size and weight of the array. In one embodiment, the shared core pieces are formed as back-to-back U-shaped members defining an indented region at the center of the core piece. In another embodiment, a plurality of small block-shaped center core pieces in each inductor defines a plurality of gaps therebetween.

Abstract: An inductor that includes end core pieces and a plurality of center block core pieces between the end core pieces that define a plurality of gaps. The end core pieces are made of an amorphous alloy to provide good magnetic field properties and the center core pieces are stamped magnetic sheets forming a laminate structure to provide ease of manufacturability. In one non-limiting embodiment, the end core pieces are an amorphous iron alloy and the center core pieces are stamped silicon-iron.

Abstract: In a DC to DC converter, first and second primary windings are magnetically coupled to a first secondary winding. Third and fourth primary windings are magnetically coupled to a second secondary winding. The first and second primary windings are magnetically coupled to the first secondary winding. The third and fourth primary windings are magnetically coupled to the second secondary winding. The first and third primary windings are coupled in series to form a first coil member. The second and fourth primary windings are coupled in series to form a second coil member. One end of the first coil member is coupled to the first positive power line. A first switching element is coupled between the first negative power line and the other end of the first coil member. A first capacitor is coupled between the first negative terminal and one end of the second coil member.

Abstract: Combined type transformer includes: a transformer core; first and second coils provided with respect to the transformer core; first and second inductor cores provided around the first coil; and third and fourth inductor cores provided around the second coil. The transformer core and the first and second coils constitute a transformer, the first coil and the first and second inductor cores constitute a first inductor, and the second coil and the third and fourth inductor cores constitute a second inductor.

Abstract: Wire-holders are provided that confine a single wire over a limited arc section and that are interspersed with ferrite ingots that provide wire-ways for several wires are utilized in the winding of the coils of a transformer. A method for consistently producing windings having accurate wire placement on rotors, stators, and other electrical componentry is also provided.

Abstract: A high voltage transformer including a transformer housing. Internal components and provided in the transformer housing. The internal components are submerged in transformer oil and are provided with insulation for insulating a high voltage winding end. The insulation includes a shield ring arranged above the winding end and a pressboard structure formed in a zigzag pattern arranged around the winding end. The shield ring includes a core covered with a conducting layer and a continuous solid insulation layer outside the conducting layer. The insulation layer includes integrated solid insulation sections of which at least some among themselves having varying thickness. Also a shield ring and a method of manufacture the shield ring.

Abstract: A transformer for use in a power supply has a primary winding, a secondary winding, a bobbin on which the primary and secondary windings are separately wound, and a core subassembly mounted in the bobbin. An opening is formed in the cylindrical portion of the bobbin, and an inside core in the magnetic core insertion hole and an outside core located outside the hole are adhesively bonded together via a spacer through the opening in the cylindrical portion.

Abstract: A non-contact signal transmission apparatus transmits electric power and a signal in a non-contact manner via magnetic induction. The apparatus includes: a pair of annular electric power cores provided in opposing relationship to each other; a pair of electric power coils respectively provided in an annular form at one of the pair of electric power cores; and a pair of signal coils respectively provided in an annular form inside one of the pair of electric power cores. Relative permeability inside and around the signal coils is lower than relative permeability of the electric power cores.

Abstract: A multi-parallel magnetic-filed cancellation type transformer includes a plurality of coils which generate magnetic flux during energization and a core having a plurality of magnetic leg portions on which the coils are wound, and bases for fixing the magnetic leg portions. The plurality of coils are wound on the magnetic leg portions in such a manner that the magnetic flux generated from the coils are formed in the directions opposite to each other. A plurality of closed magnetic circuits of the magnetic flux are formed at the magnetic leg portions and the bases. The magnetic resistance of the closed magnetic circuits is homogeneous. Accordingly, the transformer can reduce the size thereof, and prevent the deterioration of electric power conversion efficiency.

Abstract: The present invention provides an improved transformer (20), which broadly includes: a substrate (21) having first and second surfaces (22, 23); a first board (24) mounted on the substrate first surface; a second board (25) mounted on the substrate second surface; the boards being identical to one another and being mounted on the respective proximate substrate surfaces as mirror images of one another; each of the boards having a plurality of dielectric layers with electrically-conductive sheet windings (35, 36, 37, 38) embedded therein; and an assembled core (26, 28) operatively arranged to provide a path for magnetic flux attributable to a current in the some of the windings. Third and fourth boards (71, 72) may be piggy-backed onto the first and second boards, respectively, to selectively vary the properties of the transformer.

Abstract: To provide a composite magnetic device having characteristics of two magnetic elements, being capable of reducing a manufacturing cost, and preferably enabling the respective magnetic elements to easily exhibit the same characteristics.

Abstract: A reactor part includes at least a winding and a magnetic substance core, in which the core includes a pair of winding portions around each the winding is wound, and a non-winding portion around which no winding is wound, wherein a cross-sectional area in a direction orthogonal to a magnetic path of the non-winding portion of the core is made smaller than a cross-sectional area in a direction orthogonal to a magnetic path of the each of winding portions.

Abstract: A high-strength ignition coil that can prevent distortion arising from pin marks formed on a surface of a core and makes it less likely for insulating resin to be cracked. The coil assembly is housed in a coil case. A casting material is filled into a gap between the coil case and the coil assembly and gaps which the coil assembly has. The coil assembly is comprised of a coil pair including a cylindrical primary coil and a secondary coil disposed concentrically with the primary coil, and a core. The core is fitted into a central space of the coil pair and forms a magnetic path. The core is coated with mold resin. Concave portions of pin marks formed on a mold resin coating by removal of core fixing pins when the mold resin coating is formed are filled with mold resin.

Abstract: A transformer includes multiple bobbins arranged side by side, a primary winding coil, a secondary winding coil and a magnetic core assembly. Each bobbin includes a main body, multiple partition plates, a primary winding coil, a secondary winding coil and a magnetic core assembly. The main body has at least two sidewalls respectively disposed at two opposite ends thereof. The partition plates are disposed on the main body for respectively cooperating with the sidewalls to define a first winding region and a second winding region. The first winding region and the second winding region are separated by the partitions plates. The spacer is disposed within the channel. The primary winding coil and the secondary winding coil are respectively wound on the first winding portion and the second winding portion of each bobbin. The magnetic core assembly partially embedded into the channels of the bobbins and sustained against the spacer.

Abstract: In a three phase transformer core, amorphous metal strips are wound into rings that are combined into frames and assembled to define cores with leg cross sections that have more than 4 sides to facilitate winding transformer windings onto the legs using winding tubes. The amorphous metal layers are secured relative to one another and the core made more rigid using resin, silicon steel layers included in the amorphous metal core, or by using strapping or tying devices.

Abstract: An inductor includes common mode and differential mode flux paths. The inductor comprises a first core having a first segment, a second segment extending from the first segment and a first bridge segment extending from the second segment; a first wiring arrangement at least partially disposed around the first segment; a second core having a third segment, a fourth segment extending from the third segment and a second bridge segment extending from the fourth segment; and a second wiring arrangement at least partially disposed around the third segment; wherein the first segment, second segment, third segment and fourth segment cooperate to promote the common mode flux path, and the first bridge segment and the second bridge segment cooperate to promote the differential mode flux path.

Abstract: Method of forming a magnetic core or part of a magnetic core including several layers of windings of magnetic wire in a very compact configuration, and the core or part of core is formed by winding several layers of a collated band of wires side by side until desired number of layers of core or part of core is obtained. Method includes forming magnetic core or magnetic flux return path or part of magnetic core including several layers of windings of magnetic wire in compact configuration; core or part of core being formed by winding several layers of a collated band of wires side by side until reaching desired number of layers of the core or part of the core. Magnetic core or magnetic flux return path includes several layers of windings of magnetic wire in compact configuration; part of layers of windings being formed by collated band of wires.

Abstract: A transformer includes a frame type iron core having plate-shaped magnetic members. At least one of the plate-shaped magnetic members has a large width and forms a magnetic circuit in which a magnetic flux is concentrated. Each of the plate-shaped magnetic members includes magnetic member pieces. Each adjacent pair of end surfaces of the magnetic member pieces are joined together to form a joint portion. Three or more joint portions, each of which is formed, by joining together adjacent end surfaces of an adjacent pair of the magnetic member pieces included in the plate-shaped magnetic member having the large width, are shifted from each other in the direction of a magnetic path of the magnetic circuit to increase an effective cross sectional area of the magnetic path. The magnetic member pieces included in the plate-shaped magnetic member having the large width have a high magnetic permeability to reduce a magnetic resistance of the magnetic circuit.

Abstract: The invention is directed to a transformer and a method of manufacturing the same. The transformer has high and low voltage coils mounted to legs of a core. Each low voltage coil includes conductor sheeting having opposing first and second ends and opposing first and second side edges. A pair of coil bus bars is provided for each low voltage coil. Each coil bus bar has first and second portions, wherein the first portion has a width that is more than one and a half times greater than a width of the second portion. Each coil bus bar is secured to the conductor sheeting of its low voltage coil such that the first portion of the coil bus bar is disposed at the first side edge of the conductor sheeting and the second portion of the coil bus bar is disposed at the second side edge of the conductor sheeting.

Abstract: An inverter power module for use in an electric/electronic device includes a driving circuit board, a power transformer mounted on the driving circuit board, an inverter transformer mounted on the driving circuit board, and a blocking unit to block a magnetic flux that is generated from the inverter transformer from being emitted to the outside. With this, the magnetic flux that is generated from the inverter transformer is blocked from being emitted to the outside, thereby allowing an EMI noise, a heating problem, a noise of the system circuit, etc. to be minimized.

Abstract: Disclosed is a lamp transformer assembly, transformer winding arrangement and method of assembling a transformer assembly and lamp igniter transformer core. The lamp transformer assembly comprises a transformer core comprising two or more core members, wherein the core members ends are adapted to provide a transformer core with axially distributed air gaps. Furthermore, the transformer assembly comprises a primary and secondary winding, wherein one or more core members and the secondary winding are adapted to provide insertion of the one or more core members within the interior of the secondary winding. The transformer core members are attached to complete the core.

Abstract: A dual core transformer including a bobbin having a through-hole along a first direction; a first coil wound around a first portion of the bobbin; a second coil wound around a second portion of the bobbin; first and second I cores inserted into the through-hole; and first and second C cores covering the first and second portions of the bobbin.

Abstract: The present invention provides a transformer apparatus configured by integrating an inverter transformer and balance transformer to be a downsized form, and a drive circuit using the transformer apparatus. The transformer apparatus comprises an inverter transformer having a core potion on which a primary coil and a secondary coil are wound, and a balance transformer having a core portion on which a primary coil and a secondary coil are wound, wherein the inverter transformer and the balance transformer are integrally formed by sharing a part of the core portions.

Abstract: Since there exists a draw-out portion of a triple insulated wire in a winding structure of a transformer in which the triple insulated wire is used as a secondary winding, the thickness of the transformer is increased by an amount corresponding to the wire diameter of the draw-out portion. Further, when reduction of the thickness of the transformer is prioritized, the secondary winding can be provided only on one side, making it impossible to achieve the sandwich structure. Thus, the coupling between the primary and secondary windings has been sacrificed. An inductance part provided with a magnetic core, two or more sheet coils, and a winding includes: a bobbin constituted by at least two or more sheet coils; and a winding formed by winding a triple insulated wire between the two or more sheet coils constituting the bobbin. A triple insulated wire draw-out portion on the center side of the winding is drawn out to one outer surface side of the bobbin.

Abstract: A coil component has a first coil part and a second coil part, a middle member, and a shield member. Each of the first and second coil parts includes a drum core and a winding. The middle member is located between the first and second coil parts arranged in a state in which axes of winding drums in the respective first and second coil parts are parallel to each other. The shield member is formed at least in part of an outside surface of the winding in each of the first and second coil parts and is a resin containing a magnetic material powder. The magnetic permeability of the middle member is lower than that of the core and the shield member.

Abstract: Integrated circuit packages incorporating an inductor and methods for their fabrication. The lead frame used in packaging the integrated circuit includes a first area for receiving the integrated circuit, and a second area having a plurality of connections from one side to the other side of the lead frame, thereby forming coil segments. After mounting the integrated circuit and wire bonding its connections, the lead frame is placed on a ferrite plate, the assembly is encapsulated in resin, and the leads trimmed and bent. Mounting of the packaged integrated circuit on a properly prepared printed circuit interconnects the coil segments in the package to coil segments on the printed circuit, thereby forming a single, multi-turn coil around the ferrite plate. Various embodiments are disclosed.

Abstract: A signal distribution inductor is suitable to be adsorbed by a surface mounting technology (SMT) apparatus. The signal distribution inductor includes a base, a separated iron-core, and a plurality of induction coils. The separated iron-core includes a first induced body and a second induced body, wherein the first induced body and the second induced body are provided at the base. The first induced body and the second induced body are joined together to form a joining surface through which the signal distribution inductor is adsorbed by the SMT apparatus. In addition, the first induced body has a first through hole, and the second induced body has a second through hole. The induction coils are wound on the first induced body, the second induced body and the base through the first through hole, the second through hole.

Abstract: The present invention discloses a transformer structure. The transformer structure comprises a first primary winding, and a first secondary circuits. The first secondary circuits comprises a filtering capacitor, a conductive Cu windings and a rectifier configured onto the printed circuit board (PCB) forming the first secondary circuits PCB winding. The first primary winding and the secondary circuits are interleaved with each other.

Abstract: A substrate is prepared that includes substrate segments arranged in series in the X and Y directions. The substrate segments are respectively provided with circuit patterns on its one side and electrodes on the other side. Sets of IC devices including bobbins are mounted on the sides with the circuit patterns of the respective substrates. A conductor is wound around the bobbins successively to form the windings. Portions of the conductor extending between the adjacent windings are pressed against and connected to the circuit patterns to form leading and trailing ends of the windings connected to the circuit patterns. Thereafter, the substrate is severed to provide surface-mount coil packages each comprising the circuit board and the set of IC devices including the coil.

Abstract: A ferrite core includes an end face portion, a pair of outer legs protruding from the end face portion, and a center leg protruding from the end face portion between the pair of outer legs. A width W1 close to one end portion of the center leg in a Y-axis direction perpendicular to a facing direction of the outer legs is smaller than a width W2 close to the other end portion. According to this configuration, a circuit component may be positioned close to the end portion. A transformer includes the ferrite core.

Abstract: A matrix integrated magnetics (MIM) “Extended E” core in which a plurality of outer legs are disposed on a base and separated along a first outer edge to define windows therebetween. A center leg is disposed on the top region of the base and separated from the outer legs to define a center window. The center leg is suitably positioned along a second outer edge opposite the first or between outer legs positioned along opposing outer edges. A plate is disposed on the outer legs opposite the base.

Abstract: A bobbin includes a first winding frame to wrap primary winding coils thereon, a first winding chassis defining a first opening to receiving the first winding frame therein, a pair of second winding chassis positioned at two opposite ends of the bobbin and each defining a second opening, a pair of second winding frames received in the second openings of the second winding chassis to wrap secondary winding coils thereon, and a receiving hole extending through the second winding chassis and the first winding frame. The first winding frame is positioned between the second winding chassis. Each of the second winding frames defines a through hole communicating with the receiving hole. The first opening of the first winding chassis faces to a first direction, and each of the second openings of the second winding chassis faces to a second direction different from the first direction.

Abstract: An inductor includes a first magnetic substance core which has a middle leg, a first outer leg, a second outer leg, and a body portion interconnecting the middle leg, the first outer leg and the second outer leg, and a second magnetic substance core which is arranged to be opposed to the first magnetic substance core. A first conductor is arranged in a first space which is formed by the middle leg, the first outer leg, part of the body portion, and the second magnetic substance core. A second conductor is arranged in a second space which is formed by the middle leg, the second outer leg, part of the body portion, and the second magnetic substance core. The middle leg is formed with a region which is lower in height than the first outer leg, in the same direction as the longitudinal direction of the first outer leg.

Abstract: A core for a reactor includes: a plurality of core members, each of which has a convexly curved side face that serves as a bonding face; and a gap plate that is interposed between the curved side faces of the core members and that is bonded to the curved side faces. The gap plate includes a flat plate and a plurality of projections which project from each face of the plate and each of which has a tip end that contacts the curved side face. The projections are formed at positions near the outer edges of the plate, which are distant from the center of the plate at which no projection is formed, and which are at equal distances from the center of the plate.

Abstract: An inductor that includes end core pieces and a plurality of center block core pieces between the end core pieces that define a plurality of gaps. The end core pieces are made of an amorphous alloy to provide good magnetic field properties and the center core pieces are stamped magnetic sheets forming a laminate structure to provide ease of manufacturability. In one non-limiting embodiment, the end core pieces are an amorphous iron alloy and the center core pieces are stamped silicon-iron.

Abstract: Apparatus for making a helically wound conductor includes a pulling mechanism for axially advancing a cable core and a guide mechanism for axially directing one or more secondary strand(s) from a location offset from the cable core toward the cable core at a common approach angle. A mandrel body is disposed at a forward end of the apparatus, the mandrel body having an axial passageway extending from a rearward to the forward end of the mandrel body dimensioned to axially receive the cable core therethrough and a forward radiused end positioned to intercept the secondary strand(s). The secondary strand(s) converge on the mandrel radiused end at a common approach angle, tangentially intersect respective locations of the mandrel radiused end, and follow the radiused end to intersect with the cable core.

Abstract: An inductive element for transforming and/or regulating voltage input from a multi-phase, interleaved power supply system into an output voltage to a load is disclosed. The multi-phase, interleaved power supply system includes a plurality of pulsed power sources, each of which is adapted to provide voltage at a discrete phase. The inductive element includes a magnetic core having, for each power supply, a distinct area of relatively-high magnetic reluctance, which is surrounded by areas of relatively-low magnetic reluctance, and a pair of windings. Each of the pair of windings includes a first, phase winding that is electrically coupled to an output of one of the pulsed power source and to the load, and a second, loop winding that is operatively coupled and proximate to the first, phase winding. Each of the second, loop windings is disposed serially on a closed loop.

Abstract: A method of manufacturing a dry-type, resin-encapsulated transformer coil that includes forming a plurality of conductive layers and positioning a plurality of pre-formed plastic cooling ducts so as to be disposed between the conductive layers.

Abstract: A multiple phase buck converter or boost converter, or buck-boost converter has an inductor in each phase. The inductors are inversely coupled. In a first embodiment, the converter includes a toroidal magnetic core with inductors extending under and over opposite sides of the toroidal magnetic core. The coupled inductors are thereby inversely coupled and have a relatively low ohmic resistance. In a second embodiment, the converter comprises a ladder-shaped magnetic core (i.e. having parallel sides, and connecting rungs). In this case, the inductors extend under the sides, and over the rungs. Each inductor is disposed over a separate rung. The ladder-shaped magnetic core is preferably disposed flat on a circuit board. Inverse coupling and low ohmic resistance are also provided in the second embodiment having the ladder structure.