Abstract: Disclosed is a spark plug having an insulator with good breakage resistance. A spark plug 1 contains a ceramic insulator 2, a plate packing 22 and a metal shell 3. The ceramic insulator 2 has, on an outer circumferential surface thereof, a step portion 14, a leg portion 13 and a curved surface portion 31 between the step portion 14 and the leg portion 13. The metal shell 3 has, on an inner circumferential surface thereof, a taper portion 21. The ceramic insulator 2 is fixed in the metal shell 3 with the step portion 14 retained on the taper portion 21 via the plate packing 22. Herein, 50% or more of an inner circumferential edge portion IP of the plate packing 22 is in contact with a part of the ceramic insulator 2 located front of a middle region CP of the curved surface portion 31.

Abstract: The present invention provides a compact, broad-band, and low-drive-voltage optical modulator module capable of generating any multilevel optical modulation. The optical modulator module according to an exemplary aspect of the present invention includes a digital segmented electrode structure optical modulator and m individual driving circuits. The digital segmented electrode structure optical modulator includes semiconductor optical waveguides and at least m waveguide-type optical phase modulator regions. An i-th individual driving circuit includes a driving circuit and a phase shift circuit. The driving circuit amplifies a digital input signal in synchronization with a clock signal and outputs the signal to an i-th waveguide-type optical phase modulator region. The phase shift circuit applies a delay to a signal branched from the clock signal. A j-th individual driving circuit receives an output signal from the phase shift circuit of a (j?1)-th individual driving circuit as a clock signal.

Abstract: A method for manufacturing an ignition plug is provided. The method includes: preparing an insulator having a cavity provided at a leading end portion thereof by disposing a leading end of a center electrode more inwards in an axial hole than a leading end of the insulator; building the insulator in an interior of a metal shell; disposing a ground electrode at a leading end portion of the metal shell; positioning a center of a through hole of the ground electrode and a center of the cavity of the insulator; and welding the ground electrode and the metal shell together after the positioning step.

Abstract: A method for manufacturing an ignition plug is provided. The method includes: preparing an insulator having a cavity provided at a leading end portion thereof by disposing a leading end of a center electrode more inwards in an axial hole than a leading end of the insulator; building the insulator in an interior of a metal shell; disposing a ground electrode at a leading end portion of the metal shell; positioning a center of a through hole of the ground electrode and a center of the cavity of the insulator; and welding the ground electrode and the metal shell together after the positioning step.

Abstract: Provided are a semiconductor optical modulator and a semiconductor Mach-Zehnder optical modulator of high efficiency and high reliability.

Abstract: A spark plug includes: a metal shell having a mounting thread formed with a nominal diameter of M12 or smaller; a ground electrode consisting of a first structural member and at least one ith structural member (i=2, 3, 4, 5) laminated to cover an outer surface thereof, the length of protrusion of the ground electrode from a front end face of the metal shell being 4.5 mm or larger, the ground electrode having a bent portion with a curvature radius of 2.3 mm or smaller; and an electrode tip joined thereto at a position facing the front end of the center electrode and having a protrusion length of 0.5 mm or larger and a cross sectional area of 0.20 to 1.13 mm2. The ground electrode has a total thermal conductivity of 35 W/(m·K) or higher at 20° C.

Abstract: A spark plug is provided capable of speedily burn off carbon adhered on an insulator. With this spark plug, in order to improve the temperature rise performance of a front end side of an insulator 10, an amount of protrusion H (mm) of the insulator 10, a front-end side volume Vi (mm3) of the insulator 10, and a front-end side volume Vc (mm3) of a center electrode 20 are respectively defined. In consequence, it is possible to improve the recovery property of carbon fouling while retaining the voltage resistance of the insulator 10 and the durability of the center electrode 20. In addition, since the recovery property of carbon fouling improves, it is possible to prevent the occurrence of side sparks generated from the center electrode 20 to a metal shell 50 along the insulator 10, thereby making it possible to stably ensure proper ignition of an air-fuel mixture.

Abstract: A spark plug includes a ceramic insulator having an axial bore extending in the direction of an axis (CL1) and a terminal electrode inserted into the axial bore. The terminal electrode includes a rodlike leg portion inserted into the a rear end portion of the axial bore and a head portion exposed at the rear end of the ceramic insulator. A front end subportion of the leg portion of the terminal electrode is fixed to the ceramic insulator, and the leg portion has a length of 35 mm or more along the axis (CL1). The center of gravity of the terminal electrode is located in the interior of the ceramic insulator.

Abstract: A spark plug in which the center electrode is formed by laser welding along the circumference of a joint surface between a center electrode base metal and a noble metal tip in excess of full circumference. When G represents a spark gap and A represents a shortest gap between a laser weld bead and a line drawn parallel with axis X, A?3G. Straight lines S1 and S2 which connect the center of the noble metal tip 1 and the circumferential center of a proximal end 52 of the ground electrode 51 and vertex 8 of a protrusion 7 formed at a final end portion 6e of a bead 6 formed by circumferential laser welding, respectively, form an angle ? of 45 degrees. Since the protrusion 7 of the bead is the angle ? away from the ground electrode 51, an abnormal discharge is unlikely to be generated.

Abstract: A spark plug includes a tubular metallic shell extending in the direction of an axis and having a tool engagement portion formed through extrusion. The tool engagement portion has a 12-point shape which is a sectional shape taken orthogonally to the axis and has a plurality of protrusions and recesses provided alternately. As viewed in a section taken orthogonally to the axis, when D (mm) represents the diameter of a circle which passes radially through the outermost positions on the protrusions, and d (mm) represents the diameter of a circle which passes radially through the innermost positions on the recesses, the relational expression 0.45?(D?d)/2?0.75 is satisfied. The spark plug can provide a more reliable restraint on the slippage of a tool at the time of mounting and enables the tool engagement portion to be reliably formed so as to form a desired shape.

Abstract: A spark plug having an electrode, an insulator, a metallic shell, a main ground electrode, and at least two auxiliary ground electrodes.

Abstract: A method of producing a spark plug includes reducing the diameter of a center electrode while maintaining the heat dissipation property of the center electrode. A columnar member in which an outer skin member and a core member having a high thermal conductivity are clad, and which is columnarly extended, are configured by extrusion molding into a state where the thickness of the outer skin member is substantially uniform. A flange portion and a tip end portion are formed in the columnar member to obtain an electrode intermediate member. In a middle trunk portion of the electrode intermediate member, the thickness of the outer skin member is maintained. Then, the surface of the middle trunk portion is cut or polished to reduce the thickness, whereby the diameter of a center electrode is reduced while maintaining the outer diameter of the core member.

Abstract: When an insulator of a spark plug receives an external force in a bending direction perpendicular to an axis at a rear end side body portion, a position C where the insulator is supported by a crimping portion via a packing acts as a fulcrum, and a stress is applied between the position C and a position B where the insulator is supported by a ledge portion via a packing. When an insulator is designed in which the balance of size and modulus of section is adjusted so that ?A which denotes a proof strength against bending between a rear end position A of the insulator and the position C and ?B which denotes a proof strength against bending between the position B and the position C satisfy 0.71??A/?B?1.27, cracks can be prevented.

Abstract: A plasma jet spark plug comprising: a center electrode; an insulator having an axial bore extending in an axial direction, and retaining the center electrode within the axial bore; a metallic shell surrounding and retaining the insulator from outside with respect to a radial direction perpendicular to the axial direction; and a ground electrode disposed frontward of the front end portion of the insulator with respect to the axial direction, wherein the ground electrode has a contact portion contacting the front end portion of the insulator in an annular contact zone, the ground electrode is not in contact with the metallic shell with respect to the axial direction and the ground electrode is in contact with the metallic shell with respect to a radial direction perpendicular to the axial direction and is electrically connected with the metallic shell by means of an outer peripheral portion thereof being joined to the metallic shell.

Abstract: A spark plug (100) including a center electrode (130) and a ground electrode (140), which is formed by joining a ground electrode chip (143) to a ground electrode base material (141) via an intermediate member (142). A method for producing the spark plug (100) includes providing a projecting portion (142p) on the intermediate member (142), and projection-welding the intermediate member (142) to the ground electrode base material (141) by means of the projecting portion (142p), to thereby join the intermediate member 142 to the ground electrode base material (141). Further, the intermediate member (142) of the spark plug (100) includes a cylindrical columnar portion (142e) which is joined to the ground electrode chip (143), and a flange portion (142d) which is joined to the ground electrode base material (141) and which flange portion (142d) has a diameter greater than that of the cylindrical columnar portion (142e).

Abstract: For producing a spark plug that has a high dimensional accuracy in the spark gap, a method is disclosed which comprises (a) preparing a semi-finished spark plug unit (100b) which comprises a center electrode (20) that has a leading end portion (22), a metal shell (50) that holds therein through an insulator (10) the center electrode (20) except the leading end portion (22) and a ground electrode (30) fixed to a leading end of the metal shell (50), (b) bending the ground electrode (30) so that a bent front portion (31) of the ground electrode (30) projects toward the leading end portion (22) of the center electrode (20), (c) putting an electrode tip (95) on a given part of the bent front portion (31) of the ground electrode (30) in such a manner that a front portion of the electrode tip (95) projects from the bent front portion (31) toward the leading end portion (22) of the center electrode (20) and (d) welding the electrode tip (95) to the given part of the bent front portion (31) of the ground electrode (30

Abstract: The invention provides a semiconductor optical modulator including a two-step mesa optical waveguide having a first clad layer (101); a mesa-like core layer (102) formed over the first clad layer (101); and a second clad layer (103) formed into a mesa shape over the core layer (102), and having a mesa width smaller than that of the core layer (102). The two-step mesa optical waveguide includes a multi-mode optical waveguide region to which an electric field is applied or into which an electric current is injected, and a single-mode optical waveguide region to which the electric field is not applied and into which the electric current is not injected. When the mesa width of the core layer in the multi-mode optical waveguide region is defined as Wmesa1, and the mesa width of the core layer in the single-mode optical waveguide region is defined as Wmesa2, Wmesa1>Wmesa2 is satisfied.

Abstract: The cavity of a plasma jet ignition plug is configured in a stepped shape; i.e., composed of a constricted portion and a diameter-increased portion (65). The inner diameter (B) of the constricted portion is made smaller than the inner diameter (A) of the diameter-increased portion. Further, as measured along the direction of the axis O, the length (Y) of the constricted portion is made equal to or greater than the length (X) of the diameter-increased portion. This configuration suppresses a pressure loss produced when the generated plasma expands within the cavity. As a result, the energy of the plasma at the time of jetting is increased, and the igniting performance for an air-fuel mixture can be improved.

Abstract: The present invention provides a spark plug which is capable of suppressing a occurrence of crack and separation by determining a structural configuration of a melting portion formed in a junction portion between a discharge portion and a pedestal portion which form an ignition portion that protrudes from a ground electrode. In a profile line shape of a cross section including a center axis P of an ignition portion 80, an exposure surface 88 of a melting portion 83 connects a side surface 82 of a discharge portion 81 and a side surface 85 of a pedestal portion 84. Further, an exterior angle ? formed between an imaginary line Q, which passes through a boundary position X1 between the melting portion 83 and the pedestal portion 84 and a boundary position X2 between the melting portion 83 and the discharge portion 81, and the center axis P at a node C, satisfies 135°???175°.

Abstract: A sealing member for a cylindrical spark plug having a metal shell with threaded ridges thereon to be screwed into a mounting hole of a combustion engine, the sealing member comprised of a piece of annular sheet material made of austenitic stainless steel or ferritic stainless steel that is folded back in a radial direction so as to form a region where at least two or more layers of the sheet material are overlapped in an axial direction.