Abstract: The discharge lamp has a discharge vessel (10) and a socket (20) made of an electrically insulating material. Two electrodes (12, 13) project into the discharge vessel (10), with which electrical lines (16,17) are connected, which are conducted through the socket (20). A first electrically conductive component (22) is connected with the one line (16), and a second electrically conductive component (26) is connected with the other line (17), surrounds the first component (22) and is separated from it by the insulating material of the socket (20). The two components (22, 26), together with the insulating material of the socket (20), constitute a capacitive component, which is switched in parallel between the two lines (16,17), thus preventing or at least reducing the spreading of electromagnetic interference along the lines (16,17).

Abstract: A discharge lamp lighting device in which the effects of heat generated by a discharge lamp on a noise filter circuit are reduced and a sufficient installation space for the noise filter circuit is provided. The discharge lamp lighting device includes a starter circuit which generates a start signal for a discharge lamp and applies the start signal to the discharge lamp, and a noise filter circuit which is interposed between the starter circuit and discharge lamp. The noise filter circuit is disposed in a mounting member for mounting the starter circuit, or otherwise the noise filter circuit can disposed in a mounting member for mounting therein a transformer which is included in the starter circuit and is used to generate a start signal for the discharge lamp.

Abstract: A high pressure gas discharge lamp includes first and second discharge devices electrically connected in series within an outer envelope. The discharge devices each include a discharge vessel enclosing a discharge space with an ionizable fill and first and second discharge electrode assemblies. The first discharge electrode assemblies of the discharge devices are connected so as to receive a starting pulse and lamp operating voltage. Each discharge vessel includes a first wall portion spaced from the first discharge electrode assembly and defining an ionizable gap therebetween. A conductive element bridges the discharge devices at the first wall portions and capacitively couples the first discharge electrode assemblies to induce ionization in one of the discharge devices in the ionizable gap between the first wall portion and first discharge electrode assembly.

Abstract: The invention relates to a high-pressure discharge lamp (2) provided with a discharge vessel (3) and an outer envelope (30) which encloses a space (6). The lamp is provided with an igniter circuit (10) which comprises a voltage-dependent capacitor (8) and a fuse (7). According to the invention, the voltage-dependent capacitor and the fuse (7) are integrated so as to form a single component (18).

Abstract: A press sealed lamp with an internally pressed fuse is disclosed. The filament structure is conveniently formed so the fuse links across a looped section of the initial filament structure. The loop structure provides strength to the fused filament structure prior to sealing. After the lamp is sealed, a portion of the exposed loop is trimmed, thereby limiting the electrical connection to the path through the fuse.

Abstract: An ultraviolet radiation starting source for an arc discharge lamp includes a sealed envelope with a press seal, a gaseous fill material within the envelope, a molybdenum ribbon which extends from the press seal into the interior region of the envelope and a wire inlead for carrying electrical energy to the ribbon. A method of manufacture is described in which fill material flows through a tube. A press seal is formed at one end of the tube, the interior of the tube is pumped to a desired pressure and another press seal is formed at the second end of the tube to create a sealed envelope.

Abstract: A high-pressure discharge lamp has an outer bulb which surrounds a discharge vessel with intervening space. The lamp is provided with an ignition circuit which comprises a SIDAC. According to the invention, the SIDAC is mounted in a gas-filled, hermetically closed glass capsule in the outer bulb.

Abstract: A high-pressure metal vapor discharge lamp comprises: an arc tube, which is shunted by a series circuit of a thermal switch and a nonlinear ceramic capacitor, a pyroelectric current bypassing resistor connected in parallel to the nonlinear ceramic capacitor, and a lamp outer bulb incorporating the arc tube, the thermal switch, the nonlinear ceramic capacitor and the resistor. Because of this construction, the nonlinear ceramic capacitor is prevented from early deterioration, thus lengthening the service life of the discharge lamp.

Abstract: An igniter plug has a metallic shell, a front end of which has a tubular ground electrode. A hollow semiconductor tip is in the form of inversed frusto-cone shape, and placed within the tubular ground electrode. A tubular insulator is placed within the metallic shell to be in alignment with the semiconductor tip. A center electrode is placed within the insulator, a front end of the center electrode passing through the semiconductor tip to provide an annular discharge gap between the front end of the center electrode and that of the ground electrode. A low resistor layer provided on a front end surface of the semiconductor tip. An electrical resistance of the layer is determined to be smaller than that of the semiconductor tip, while a thickness of the layer is such that the layer precedes the semiconductor tip in forming a discharge path between the front end of the center electrode and that of the ground electrode only during a predetermined period after the igniter plug is initially operated.

Abstract: A cathode ray tube having an electron gun assembly in which a plurality of electrodes constitute an electron beam generating unit for generating electron beams, and an electron lens unit for focusing the generated beams on a predetermined location on a phosphor screen. The electron gun assembly further contains a pair of insulating support rods for supporting the electrodes, a resistor unit for applying a voltage to at least one of the electrodes. A metal ring is mounted in contact with a predetermined electrode of the electron lens unit and surrounds the insulating support rods. Terminal voltage pickup terminals apply a voltage to the resistor unit. At least a first and second intermediate voltage pickup terminal supply a voltage from the resistor unit to a first and second electrode. The first and second intermediate voltage pickup terminals are located in relation to the metal ring such that a discharge is prevented and image quality is preserved.

Abstract: The invention relates to a high-pressure discharge lamp provided with a discharge vessel enclosed with intervening space by an outer bulb. An ignition circuit includes a voltage-dependent capacitor. According to the invention, the capacitor is mounted in a gas-filled glass capsule in the outer bulb.

Abstract: A metal vapor discharge lamp comprising a FEC. a semiconductor switch and a thermal response switch and operated at a supply voltage of 100 to 130 V. The thickness if the FEC is 0.45 to 0.8 mm and the breakover voltage of the semiconductor switch is 60 to 100 V so that the discharge is safely caused in a light emitting tube and lighting at a voltage of -10% of the rated voltage is enabled. The open time of the thermal response switch is not less than 30 seconds so that starting is ensured even when the dimension of the light emitting tube is long or the pressure of xenon is high.

Abstract: A negative glow discharge lamp device has a discharge container enclosing at least a rare gas, a hot cathode disposed in the discharge container and coated with a thermion radiation matter, and an anode located in a negative glow domain formed between the anode and the hot cathode in the discharge container, a power conversion circuit for driving the lamp device includes a rectifier directly connected at its d.c. output terminals to the hot cathode and the anode respectively for supplying d.c. electric power to the discharge container, and a capacitor ballast connected between a power supply terminal of an a.c. power source and an a.c. input terminal of the rectifier for controlling discharge current in the discharge container.

Abstract: A thermal-switch instant starter for a fluorescent light which initiates a high voltage instantly across its electrodes comprises a high voltage initiating tube including therein a fixed electrode and a movable electrode oppositely spaced from each other to form a short circuit for initiating the fluorescent light. The movable electrode is a thermal switch constantly disposed in contact with a heater element which is disposed on the fixed electrode. An SCR automatic charging and discharging circuit is connected between the fixed and movable movable electrodes and automatically control the charging and discharging process.

Abstract: A high intensity discharge lamp (e.g., a metal halide) containing an arc tube having first and second electrodes respectively sealed at opposite ends thereof. An outer envelope surrounds the arc tube and has a lamp base disposed at one end thereof. The lamp base has first and second terminals for electrical connection to the arc tube. The lamp further includes means for electrically coupling each of the base terminals to a respective electrode of the arc tube. A starting circuit is disposed within the lamp electrically connected in parallel with the arc tube. The starting circuit comprises a non-linear dielectric element (e.g., a non-linear capacitor) and a glow capsule. The glow capsule is located within the outer envelope proximate the arc tube and adapted to produce ultraviolet radiation.

Abstract: An ignition amplifier device for the secondary circuit of an ignition system comprises the series connection of a spark gap having an electrode spacing of between 0.05 and 0.2 mm with a condenser. The so formed series connection is shunted to the electrodes of the spark plug.

Abstract: A negative glow discharge lamp of small size comprising a cylindrical discharge container enclosing at least rare gas, a hot cathode disposed in the discharge container and coated with a thermion radiation matter, and an anode disposed in a negative glow domain formed between the anode and the hot cathode in the discharge container. In the discharge lamp, the outer diameter D (mm) of the discharge container is selected to satisfy the relation3 W.sub.L <D<10 W.sub.Lwhere W.sub.L the electric power consumption (W) of the discharge lamp when the length L (mm) of the discharge container lies within the range of L=25 to 100 mm.

Abstract: In a fluorescent lamp, a starter assembly is disposed in a base of the lamp. The starter assembly includes a circuit board having conductive runs thereon and adapted to support therefrom lamp starter circuit components that are connected to these circuit runs. One or more electrodes of the lamp couple to the printed circuit board conductive runs. The circuit board assembly is supported in the base of the fluorescent lamp.

Abstract: Low-pressure mercury vapor discharge lamp having a discharge vessel which is sealed in a gastight manner and is formed in such a way that the ends at which the electrodes are located are adjacent. The ends are secured to a lamp cap having a shell accommodating a starter and possibly a capacitor. The shell has guide walls for guiding an inner pair of electrode leads past the starter. The electrode leads, starter leads and capacitor leads terminate near the open end of the shell for ease of connection. The open end is closed by a cover with a snap connection. Current connection pins are adjacent the shell and are aligned with an outer pair of electrode leads for ease of assembly.

Abstract: A metal halide arc discharge lamp comprises an arc tube containing a chemical fill including mercury and metal halides and having first and second electrodes respectively sealed at opposite ends thereof. An outer envelope surrounds the arc tube and has first and second terminals for electrical connection thereto. A source of ultraviolet radiation is provided within the outer envelope proximate the arc tube for producing radiation which illuminates the path between the electrodes of the arc tube to decrease the amount of time for generating a gaseous discharge therebetween. The ultraviolet light source includes an envelope of ultraviolet light transmitting material containing a fill material and having a single electrode sealed in one end thereof. The single electrode is electrically coupled to one electrode of the arc tube.

Abstract: A metal halide arc discharge lamp comprises an arc tube containing a chemical fill including mercury and metal halides and having first and second electrodes respectively sealed at opposite ends thereof. An outer envelope surrounds the arc tube and has first and second terminals for electrical connection thereto. An electrodeless source of ultraviolet radiation is provided within the outer envelope proximate the arc tube for producing radiation which illuminates the path between the electrodes of the arc tube to decrease the amount of time for generating a gaseous discharge therebetween. The ultraviolet light source includes an envelope of ultraviolet light transmitting material having opposing ends. Portions of the envelope of the ultraviolet light source are capacitively coupled across the electrodes of the arc tube such that the source produces ultraviolet radiation during lamp starting when the first and second terminals of the lamp are energized.

Abstract: A plasma generator for exciting electrons in the plasma to a uniform energy evel. In a perferred embodiment, two sets of mutually perpendicular electrodes surround a container of gas, with one set being driven through a ninety degree phase shifter to establish a circularly polarized field in the space within the container. Alternative means are disclosed for launching circularly polarized RF waves into the container of gas. A desired level of uniform electron energy is achieved by establishing the proper relationship between the frequency and magnitude of the applied circularly polarized field and the mean free path of the electrons in the plasma.

Abstract: An arc discharge lamp assembly simulating the appearance of a gaslight for installation in an existing incandescent light fixture. The assembly includes an arc discharge lamp having electrical contact means (e.g., a pair of contacts on the base of the lamp) located at one end thereof. A mantle supported by a wire frame substantially encloses the arc discharge lamp. In a preferred embodiment, the lamp includes at least two longitudinally extending leg members having a predetermined spacing therebetween and joined together by a transversely extending envelope portion. A diffusing means is disposed adjacent the leg members to provide an appearance of a substantially uniform light output from the entirety of the envelope during operation of the lamp.

Abstract: In a spark plug connector for a high-voltage distributor-less high-voltage capacitor ignition system, comprising an ignition transformer and a storage capacitor connected on the secondary side to the ignition transformer, the spark plug connector is made rod-shaped with diameter dimensions corresponding to those of a spark plug and contains the storage capacitor and ignition transformer arranged one behind the other, the ignition transformer being disposed at the end of the spark plug connector remote from the spark plug connection.

Abstract: An ignition plug suitable for igniting meager fuel vapor/air mixtures has a tubular metal housing, an insulating body which is divided into longitudinal portions and contains a connection pin and a middle electrode positioned in its through borehole. A longitudinal portion of the insulating body, which longitudinal portion is enclosed by the metal housing, consists of dielectric material and, together with the metal housing and the connection pin, forms a capacitor which has a capacity of 120 to 500 pF, chiefly 200 to 400 pF. In order to connect electrial flashovers between the connection pin and the metal housing in the areas of the separating surfaces of the insulating body annular electrical insulating elements are arranged between the separating surfaces which are made of the material elastic at all temperatures of the ignition plug.

Abstract: A high pressure metal vapor discharge lamp comprises a light-emitting tube in which a pair of electrodes is enclosed, a starting element including a normally closed-type thermal switch and a resistive member, the starting element generating a pulse by closing and opening switch operations, a connecting element for electrically connecting the starting element to the electrodes, the pulse being applied to the electrodes through the connecting element, and a member including an insulating body provided in vicinity of the thermal switch for causing a conductive portion to be formed on the body, the conductive portion being sufficient to bypass a current supplied to the starting element by repetitions of the switch operations, thereby lowering the pulse voltage.

Abstract: An apparatus and method for increasing the reliability of an arc discharge occurring in metal halide gas discharge lamps by providing UV radiation in the gas discharge path.

Abstract: A discharge lamp is provided with a starting aid in the form of a loop of conductive wire arranged around the discharge lamp arc tube and a novel spark gap. A conductive element is electrically connected between the loop and an insulating sleeve adapted to form a spark gap by means of the conductive element wrapped around an opening in the insulating sleeve. The opening can be in the form of a drilled hole or slot and the arrangement is particularly useful in the restricted confines of a sealed beam reflector lamp.

Abstract: An arrangement for the ignition of ignitable mixtures, especially a spark plug for producing sparks in otto-engines, which is constructed according to high-frequency standpoints and in which at least one condenser arranged in the spark plug is adapted to be charged to a high voltage and is adapted to be discharged as much as possible exclusively in the breakdown phase of the starting phase of the ignition spark by way of a booster gap also arranged in the spark plug and a main gap formed by an ignition electrode with respect to a ground electrode, whereby the breakdown voltage of the booster is higher than the breakdown voltage at the main gap. In particular, for achieving a compact constructive form, satisfactory from a manufacturing point of view, and for optimizing the ignition and flame development, the condenser and the main gap are connected in a series circuit in a preferred embodiment of the invention, with respect to which the booster gap is connected in parallel.

Abstract: To increase the spark energy being transferred from a spark plug to a fuel-air mixture, so that the maximum energy transfer occurs during the initial breakdown phase and electrode deterioration at the spark plug is prevented upon occurrence of subsequent arc conduction and glow phases, an inductive circuit is connected in parallel to the spark gap which is so dimensioned that the inductance has a time constant which inhibits substantial current flow through the shunt circuit upon breakdown of the spark gap, but permits flow of current during an arc and glow phase of the spark at the spark gap through the shunt circuit so that energy is drained from the spark gap during the plasma and glow phase.

Abstract: The invention provides a linear beam tube which may be protected against high voltage arcs between the cathode and anode of its electron gun by connecting to ground a limiting impedance in a series path from said anode. The anode is carried upon the end of a ceramic cylinder which is co-axially within a conical metallic member. The end of the ceramic cylinder remote from the anode is attached to one end of said conical metallic member, the other end of which is flanged, with the flange passing through the tube envelope to provide an external termination which may be connected to ground. Resistive material is deposited in a groove in the inner surface of said ceramic cylinder to form a deposited impedance which extends from the anode over the end of the ceramic cylinder, to the end of the conical metallic member and constitutes said limiting impedance.

Abstract: An improved spark plug, capable of suppressing radio-frequency electromagnetic interference from internal combustion engine ignition systems such as those commonly used in motor vehicles, is disclosed. The plug comprises a shell releasably engageable with an engine, an insulator mounted in the shell, a center electrode seated within the insulator and a ground electrode structurally integral with the shell and in spark gap relationship with the center electrode. The spark plug is further characterized in that at least a portion of its insulator has a dielectric constant sufficiently high that the effective dielectric constant of the insulator is at least 30, and the relationships among the elements of the spark plug and the effective value of the dielectric constant of the insulator are such that the spark plug has a capacitance of at least 20 picofarads. Preferably, the spark plug has a capacitance of from 20 to 100 picofarads, most desirably from 30 to 80 picofarads.

Abstract: To increase the spark intensity delivered from a spark plug, an auxiliary spark gap (33) is serially connected with an auxiliary capacitor (37) and the main spark gap (42), the auxiliary capacitor being charged through a charging circuit including a resistor (45) connected in shunt to the auxiliary spark gap (33) and the auxiliary capacitor, and a further or second resistor (46) connected in shunt across the auxiliary capacitor and the ground or chassis electrode (15), and a shunt capacitor (51) is connected between the main spark plug terminal (27) and the ground or chassis or counter electrode (11, 15) so that, upon breakdown of the auxiliary spark gap, the main spark gap will have a voltage thereacross formed by the charge voltage of the main or shunt capacitor (51) and the additional voltage on the auxiliary capacitor (37) which had been charged through the resistors connected across the auxiliary capacitor and to the main spark plug terminal (27) and the ground terminal or electrode (15) respectively.

Abstract: There is disclosed a high pressure metal vapor discharge lamp which contains in an outer bulb a starting circuit connected in parallel with a light emitting tube having at least one pair of main electrodes. The starting circuit includes a ceramic capacitor surrounded by glass material and exhibiting a non-linear voltage-charge characteristic.

Abstract: It is known that electrical discharges in capillary tubing shows a positive volt-ampere characteristic even for low pressure gas fills. In contrast, conventional fluorescent lamps exhibit a negative volt-ampere characteristic and, accordingly, require special ballast circuits for operation. In the present invention, a fluorescent lamp comprises a plurality of discharge tube sections which are connected by capillary tube sections to provide the necessary ballasting action to prevent lamp current runaway. In one embodiment of the present invention, the ballastless lamp is configured in a compact configuration which may include much simpler ballast components configured in a package similar to a conventional screw-in incandescent lamp.

Abstract: A high intensity discharge lamp, for example a high pressure sodium or sodium halide lamp, which utilizes a refractory metal spiral with positive electric potential applied to it positioned around the arc tube to aid in starting and inhibit sodium migration through the arc tube during operation.

Abstract: A compact fluorescent lamp having a chassis member including a cylindrical part including a generally cylindrical thread portion and a cylindrical straight portion. A longitudinal recess is provided on the outside of the cylindrical part. The chassis member also includes a holding plate and a maintaining plate including an edge wall member and projections having notches. A screw base is secured to the thread portions of the cylindrical part and a base member is attached to the cylindrical part. A winding envelope formed by bending a straight tube twice into U-shapes and a ballast are respectively mounted to the maintaining plate and the holding plate, and a globe member is attached to the base member.

Abstract: A high frequency coil including an inductance device formed by fitting a pair of electrode caps at both ends of a ferrite magnetic core wound by a winding on a peripheral surface of the core; a heat resistant electric insulating coated layer formed on the peripheral surface of the inductance device and a heat resistant electric insulating resilient tube fitted onto the peripheral surface of the coated inductance device.

Abstract: Low-pressure mercury vapor discharge lamp having a discharge vessel (1, 2, 3) which contains with mercury and a rare gas and is of such a shape that the ends of the discharge vessel where the electrodes (4, 5) are arranged are in a side-by-side relationship, these ends being connected to a lamp base (8) which has an axially projecting sleeve-shaped wall portion (12) of a cross-section which deviates from the circular and in which at least a starter (13) is included, a respective connecting pin (10, 11) which is shorter than the length of the projecting wall portion being provided on either side of the said projecting wall portion.The projecting portion serves as a locating guide when inserting the lamp base in a holder (15), thereby inter alia preventing damage to the pins, and also serves as a housing for a starter switch (13) and a capacitor (14).

Abstract: A compact fluorescent lamp having a chassis member, a screw base screwed to the chassis member, a base member secured to the chassis member, a winding envelope having bent part and both ends oriented to the same direction, a ballast surrounded by the winding envelope and a globe member attached to the base member. The ballast is disposed between the bent part and the ends of the winding envelope so as to provide the winding envelope with a desirable coolest wall temperature.

Abstract: A bifilar helical electrode arrangement for the transverse gaseous laser media and particularly adapted to produce laser radiation in those gaseous laser media, such as nitrogen, which are characterized by an extremely short lifetime of the upper laser level. As a consequence of the electrode geometry, the invention favors the generation of laser beams exhibiting a circular symmetric beam cross section which can easily be focused using customary spherical optics. The invention incorporates intertwined helical anode and helical cathode structures together with capacitors that are connected to the helical electrode structure via low-resistance and low-inductance leads or are directly interposed between successive convolutions of that helical electrode structures.

Abstract: A gas-discharge display device for a flat and fluorescent screen is provided with at least one grid electrode between the matrix-driven control disc and the anode of the fluorescent screen for the specific field distribution in the acceleration space, the grid electrode or electrodes being connected to a respective fixed potential.

Abstract: An RC composite component with a spark gap comprises a pair of discharge electrodes defining the predetermined spark gap and formed on a dielectric substrate. The discharge electrodes are coated with a film of varnish with a controlled thickness by the screen process.

Abstract: A fluorescent lamp having a triple-U-bent tubular envelope is combined with circuit means, a translucent protective cover and a threaded base member to provide an efficient screw-in type lamp unit of high brightness and long life that is compact enough to be used as a direct replacement for incandescent type lamps in fixtures designed for residential and commercial lighting. Various structural arrangements for including the ballast and starter components of the energizing circuit as integral parts of the compact lamp unit, despite the stringent space limitations, and also venting the cover and base structures to provide convection cooling of the compacted electrical components are also disclosed.

Abstract: A fluorescent lamp having a plurality of columns positioned in a generally uniform manner within the lamp envelope, each column having an electron emissive cathode mounted therein connected to a cathode leadwire. An anode member connected to an anode leadwire extends to the upper portions of each column. A conductive starter member is mounted within each column so as to provide a first gap between one of its ends and the cathode and a second gap between the other of its ends and the associated anode extension. A D.C. voltage is applied to the anode and cathode leadwires, the D.C. voltage being obtainable from an external A.C. source via a suitable voltage rectifier/multiplier circuit which is positioned within the re-entrant stem member of the lamp.

Abstract: An integral fluorescent lamp-ballast unit comprises a fluorescent lamp fastened to an end cap at one end and a housing at the other end. An elongated support member extends between the end cap and the housing, is fastened to both, and serves as a backing for the lamp. The ballast comprises a choke and a preheat starter which are disposed in the end cap and/or housing.

Abstract: A single-ended fluorescent lamp having a partitioned envelope is coupled to a threaded screw-in type base and a module that contains a miniaturized electronic circuit which permits the lamp to be started and operated on direct current from an AC power source. The resulting compact fluorescent lamp unit can thus be used as a direct replacement for incandescent lamps in fixtures that are designed for residential and commercial lighting. Cataphoretic pumping and accumulation of the mercury vapor in the vicinity of the cathode during DC operation and short-circuiting of the partition by the arc discharge are both prevented by a diaphragm assembly at the electrode-end of the envelope which includes a porous gasket of fibrous material that is permeable to mercury vapor but constitutes an impenetrable barrier to the arc.

Abstract: A high intensity light source having high repetition rate and narrow pulse-width. The light source comprises a metal casing having coaxially mounted arcing electrodes therein which utilize the capacitance of the coaxial system to charge up to the arcing potential. One electrode is electrically connected to the end wall of the casing to provide a reflected wavefront from the end wall after an arc has been struck, such wavefront serving to extinguish the arc and thus provide a sharp pulse. The lamp may be used for such areas as photochemical and photobiological research, in place of much costlier nanosecond lasers.

Abstract: An improved control circuit for an electric discharge lamp includes a temperature-dependent capacitor connected in series or in parallel with the discharge lamp. The capacitor preferably has a negative temperature characteristic and is responsive to the heat generated in the discharge lamp. During the start-up period, the lamp temperature is low and the capacitance is relatively high, whereas in the operating condition of the lamp its temperature increases and the capacitance of the capacitor drops to a relatively low value. In the series arrangement, the starting current of the lamp is thereby increased over the operating current to promote better ignition of the lamp. Similarly, in the parallel arrangement the high capacitance capacitor facilitates lamp ignition, whereas during normal lamp operation the low capacitance shunt branch effectively appears as an open circuit exerting minimal influence on the lamp operation.

Abstract: A spark plug cap is provided for use on a spark plug of an internal combustion engine to intensify sparking across the gap between central and ground electrodes of the plug. The spark plug cap includes a cap body which comprises upper and lower insulating body sections detachably interconnected together. The upper body section is provided with a terminal head adapted to be connected to an ignition current supply cord, while the lower body section with a connector socket for mechanically connecting the cap to the spark plug. A conductor rod extend through the cap body to electrically connect the terminal head with the center electrode of the spark plug. At least one capacitor unit is supported within the cap body and connected in parallel to the spark gap between the plug electrodes. The capacitor unit includes a cylindrical dielectric and a pair of electrodes positioned on the opposite end faces of the cylindrical dielectric.