Exemplary embodiments of a gas pressure regulator comprise a regulator body, an adaptor sleeve, a retainer and an indexing ring. The regulator body includes a proximal portion, a distal portion, a ported intermediate portion therebetween, and a main bore. The adaptor sleeve axially receives the distal portion and includes an outer threading for engaging an air source adaptor of a paintball marker. The retainer threadably engages the main bore within the distal end, thereby axially securing the adaptor sleeve onto the distal end. The indexing ring receives the distal portion therethrough for resiliently biased axial movement of the indexing ring between a locking position and an unlocking position. When the indexing ring is in its unlocking position, the adaptor sleeve is rotatable with respect to the regulator body. When the indexing ring is in its locking position, the adaptor sleeve is rendered substantially non-rotatable with respect to the regulator body.

A projectile shooter toy has a body with a sidewall forming a space for holding a projectile in a loaded state and a pathway leading away from the space and along which the projectile moves in a forward direction. An actuator is arranged to engage the projectile to move the projectile forward along the pathway. At least two pinching members are spaced forwardly along the pathway from the actuator. The pinching members are separate from, and movable relative to, the actuator and the sidewall, and are configured to exert a force on the projectile as the projectile passes between the at least two pinching members.

This invention belongs to the group of projectile throwing instruments working without an explosive or a combustible propelling charge in particular to the group of projectile throwing instruments using strained hard body energy and can be used for the design and construction of a missile throwing weapon using a string—namely a bow and crossbow.

An archery bowstring release has a single jaw for retaining a bowstring within a bowstring hook, in contrast to dual-jaw pincer-type releases. The bowstring hook is situated on a release head which bears a trigger for actuating the jaw and releasing the bowstring, and a release body extends between the release head and a release mount (which can connect the bowstring release to a wrist strap, glove, or other anchor affixed to the user's body). The release head and body are pivotally joined, and when the release is ready to fire, the central axis of the release body, and at least the rear of the release head, have central longitudinal axes which are aligned with the notch in the bowstring hook, and are thus aligned with the bowstring, and are parallel to or in line with the arrow. The release therefore has a comfortable, natural, and intuitive feel during operation.

A toy having a housing; a cover pivotally mounted to the housing for movement between a first position wherein an internal cavity of the housing is covered and a second position wherein access to the internal cavity is provided; a launching mechanism located within the internal cavity; a first projectile configured to be launched from the launching mechanism; a plurality of second projectiles configured to be launched from a plurality of projectile launchers secured to the housing; an actuation mechanism coupled to the cover, the launching mechanism and the plurality of projectile launchers, wherein operation of the actuation mechanism causes the cover to move from the first position to the second position and simultaneously launch the first projectile and the plurality of second projectiles from the launching mechanism and the plurality of projectile launchers.

An archery bow is comprised of at least a riser and two limbs that can be folded into a position forming its own case to protect the limbs, or taken down and reassembled with limbs of various draw weights. When taken down it may also be reconfigured to enable use by an archer with opposite handedness. In its folded state it is highly compact and transportable.

A toy pump action rifle for launching discs having an outer housing, a stock, a grip, a trigger, a handle for cocking the rifle and a revolving drum for storing multiple discs. Within the housing is a mechanism for removing discs, one at a time, from the drum where the discs are arranged in a first position, rotating each disc 90° to a second position, and transporting each disc to a discharge chamber. The mechanism includes a transfer arm to remove each disc from the drum, a disc pocket for receiving the removed disc, the pocket being rotatable to reorient the disc, and disc pocket also being slidable to carry the disc to the discharge chamber. Activation of the trigger releases a cocked launch arm that snaps forward and strikes the disc to cause discharge.

The present invention relates to a device for delivering targets (2) comprising at least one column (4) for storing targets (2) capable of receiving a first target (11) at the lowest point of the column (4) and at least a second target (12) stacked on the first target (11), means for delivering the first target (11), and retention means for retaining the second target (12) in the column (4), characterized in that the retention means for retaining comprise a ramp (21) configured to exert a bearing force on the lower face of the second target (12) during the delivery of the first target (11). This invention also relates to a machine for launching targets (2) equipped with a device and a method for distributing the targets (2).

A sight and range finder for a projectile launching device are disclosed. The range finder calculates a range between a target and a projectile launching device, and transmits a signal indicative of the range. The sight visually aligns the target with the projectile launching device. A drive assembly moves an alignment member of the sight, and at least one processor receives the signal and actuates the drive assembly to move the alignment portion a selected distance based on the range.

A traditional archery bow assembly includes a handle assembly, a bowstring, and a first limb bolt assembly. The handle assembly includes a riser, an upper limb, and a lower limb, wherein the upper and lower limbs each include a distal end and a proximal end connected to the riser. The bowstring extends between the distal ends of the upper and lower limbs. The first limb bolt assembly is operable to connect one of the upper and lower limbs to the riser. The first limb bolt assembly includes a shank portion and a head portion, wherein the head portion defines a contact surface that faces and contacts the one of the upper and lower limbs, and is pivotable relative to the shank portion.

An electric toy gun with a plurality of firing modes includes a trigger, a power break holder, a power contact holder, a block member slidably coupled to the power break holder and having a first tooth and a second tooth at one lateral side thereof, a swing bar having an actuation portion and a push block connected to the actuation portion. A control mechanism enables the push block of the swing bar to be shifted to the rear side of the first tooth, the rear or front side of the second tooth. Lowering of the power break holder with the block member drives the push block to move the first or second tooth forward and then to push the first tooth forward. The block member is displaced relative to the stop portion of the link which moves the power break holder.

According to an exemplary embodiment, a toy dart launcher comprises a housing defining an interior recess and a launch assembly. The launch assembly is at least partially disposed within the interior recess and comprises: a projectile feed, a slidable frame, and a launch mechanism. The projectile feed is rotatably disposed within the interior recess and comprises a plurality of receiving chambers each adapted to receive one or more projectiles. The slidable frame has at least one engagement finger rotatably disposed thereon, and is movable with respect to the projectile feed so that the at least one engagement finger can engage and move at least one projectile through at least one receiving chamber. The launch mechanism is disposed rearwardly of the projectile feed and is configured to create a pressure differential about the at least one projectile so that the at least one projectile can be launched from the housing.

A universal wrist strap, for connection to a plurality of different bowstring release mechanisms via a plurality of different connecting members, includes a flexible base member adapted to fit around the wrist of a user and a mounting assembly connected to the wrist strap. The flexible base member has first and second arms that converge towards an apex area. The mounting assembly is connected to the apex area and is adapted to receive and retain the plurality of different connecting members.

A dart launcher comprises a housing, a safety arm, and a trigger. The housing includes a launching section configured to receive a dart having a minimum threshold length. The safety arm is movably attached to the housing and extends at least partially across the launching section. The safety arm is positioned so that the dart having the minimum threshold length engages at least a portion of the safety arm upon insertion into the launching section. The trigger is movable with respect to the housing and is operable to cause the dart having the minimum threshold length to launch from the launching section.

The present invention relates to a three dimensionally fiber-reinforced riser and to the unitary or single-step methods of making the same. In one embodiment (a cross bow riser for example), the riser has an interior support with opposed side members and a front brace. The front brace has a depression centrally located therein. Two side ribs are also provided for structural support. Two pockets each optionally having a divider wall defining a top and bottom section are provided for receiving respective top and bottom pieces of a split limb, when a split limb is used. The riser can be made of a composite material having fibers aligned there within in the directions of the highest stresses for enhancing the structural strength of the riser. Other bow parts or components can likewise be made via composite material as well.

The apparatus for mounting at least one dampener and/or stabilizer to an archery bow to absorb shock and vibration realized by an archer upon the release of the archery bow. The present invention provides an elongated support structure releasably connectable to the at least one dampener and/or stabilizer. A releasable fastener is connected to one end of the support structure, and the releasable fastener is releasably connectable to the archery bow such that the support structure is extendible in a cantilevered position relative to the archery bow.

An archery bow vibration dampening and balancing device is attachable to an archery bow by means of an elongated clamp with a housing pivotably interconnected to the elongated clamp opposite the attachment point. A vibration dampening and balancing device is secured in an opening formed in the housing.

An archery stabilizer which, by utilizing a carbon fiber tube or a comparable material in a tube configuration, provides for preloading the tube in compression, thereby effectively increasing the stiffness of the tube. The stabilizer includes weights, and the preloading of the tube compensates for the bending moment applied to the tube by the weights attached to the end of the tube or contained within the tube. In effect, the present invention presents an apparatus and method for loading the tube so as to allow a user to adjust the elastic modulus of the tube.

A face-driver assembly and method for accurate coupling of a face driver with the spindle of a rotary-drive machining device. The assembly includes a face driver, a hub on the spindle defining a prealignment bore, a pair of self-centering coacting tooth sets on the hub and face driver, an engagement post extending into the hub and forming a prealignment shaft closely complementary to the prealignment bore, and a releasable coupling to hold and draw the engagement post rearwardly and thereby join the tooth sets in a manner facilitating final accurate centering.

A manually directed lathe tool system for removal of internally disposed material and creating a void inside a lathe turned form. As shown in FIG. 1, an articulated boring bar (32) of a tubular crosssection is slidably manipulated and supported by a plane surface (140) during a cutting action. To increase offset cutting ability several different lengths of a detachable and hinged arm assembly (40) are used. Arm assembly can be fixed or moved to three different positions relative to boring bar (FIG. 2) by manipulating a hand knob (36). A moveable and replaceable cutting tool (198) is held at the end of the arm assembly. A wall thickness caliper system (44) which ends in a tip (130) of some flexible material to allow operator appraisal of the internally disposed cutting tool's position. A back restraint assembly (141) is used to prevent the downward pitch of the boring bar's cutting end during material removal and consequent upward pitch of the opposite end of the boring bar, and especially during a highly leveraged cutting action. An outrider (38) attached to the boring bar prevents rotational movement of the tool relative to its longitudinal axis, especially during a leveraged offset cutting action. The outrider is able to be attached at several different locations on the boring bar and also serves as the support for the caliper system. Platform base (34B) is mounted rigidly to the lathe bed (30) and maintains platform assembly (34A) at a proper height. A precise wall thickness that mirrors the outside form can be achieved with this system. The system can be used to hollow-out forms not possible with previous practice. A narrow and restricted mouth opening does not hinder hollowing-out large diameters and deep forms. The operator is in control during all leveraged cutting actions and experiences minimal operator fatigue.

A copying cutting device for wood lathes including two securing stems, two form securing devices each transversely mounted at the bottom end of each securing stem, a guide track device mounted above the securing stems, a cutter mounting device having a cutter mounted thereon screwably provided at the bottom side of the guide track device, and a form tracing device screwably disposed at the rear end of the cutter. The forms securing device positions a copy, and a tracing rod of the form tracing device urges against the tracing edge of the copy. The cutter slides in the cutter mounting device, which in turn slides in the guide track device. The cutter cuts the workpiece following the contour of the copy with the help of the tracing rod.

A saw for simultaneously cutting and beveling including a cut-off saw, a cutting blade, and a beveling blade. The cutting blade cuts simultaneously while the beveling blade bevels. The beveling blade preferably has a head with two faces annularly connected by an annular slanted circumference. The head has at least one notch suitable for accommodating a respective at least one tooth insert interconnected with a respective at least one cartridge. Each cartridge is interconnectable with a respective tooth insert.

A tailstock assembly mountable on a machine tool and cooperable with a headstock assembly for retaining a workpiece inbetween.

A wood lathe includes first and second seats disposed respectively and fixedly on two ends of a table. A first driving device includes a motor disposed on the second seat, an outer tube fixed between the first and second seats, and a rotating inner rod journalled within the tube and connected to the motor by a belt and pulley unit. An output shaft is journalled on the first seat, and is provided with a fixed first clamping element. A second clamping element is disposed adjacent to the second seat so as to clamp a workpiece between the first and second clamping elements. A second driving device is disposed within the first seat, and interconnects the shaft and the rod to transfer rotation of the rod to the shaft, thereby rotating the workpiece.

A system and method allows visual programming of simultaneous and synchronous machining operations on multi-axis lathes. The system and method accounts for different combinations of simultaneous and synchronized lathe operations on the spindles which can utilize multiple tools. A graphic synchronization icon is assigned to each mode that preferably represents the lathe operation. Appropriate synchronous operations are grouped together in synchronization groups. The system and method are universal since a postprocessor processes the synchronization modes and synchronization groups, and translates them for use with computer programs understood by a particular CNC lathe.

A cutting tool piece is provided including a rear portion and a lead portion, the lead portion including a front section having an upper side angled downwardly and forwardly and a lower side angled upwardly and forwardly to form a transverse lead cutting edge. The rear portion includes a hole to secure the tool piece to a cutting tool and transverse cutting edges extending outwardly from side walls of the front section. A system is also described for cutting a bowl by coring out an interior portion of a wood block by applying the cutting tool which is curved and rotatably mounted to a post. Its lead end with the tool piece attached creates a circular groove. The cutting tool is advanced on a path which curves toward the central axis of the lathe.

A hollowing system for a lathe having a tool rest. The hollowing system comprises a boring member, and a stabilization assembly. The boring member is adapted to support a tool such that at least one of the boring member and the tool extend past and engage the tool rest. The stabilization assembly is mountable adjacent to the lathe. The stabilization assembly supports the boring member such that the boring member extends generally parallel to a longitudinal axis of the lathe. The stabilization assembly has a vertical axis and a horizontal axis. The stabilization assembly is adapted to prevent downward movement of the tool when the stabilization assembly is mounted adjacent to the lathe and the tool is positioned on the tool rest. The stabilization assembly is provided with an articulation assembly. The articulation assembly supports the boring member and permits horizontal movement of the boring member about the vertical axis, while also permitting lateral movement of the boring member in a horizontal direction.

A cutting tool piece is provided including a rear portion and a lead portion, the lead portion including a front section having an upper side angled downwardly and forwardly and a lower side angled upwardly and forwardly to form a transverse lead cutting edge. The rear portion includes a hole to secure the tool piece to a cutting tool and transverse cutting edges extending outwardly from side walls of the front section. A system is also described for cutting a bowl by coring out an interior portion of a wood block by applying the cutting tool which is curved and rotatably mounted to a post. Its lead end with the tool piece attached creates a circular groove. The cutting tool is advanced on a path which curves toward the central axis of the lathe.

A lathe accessory for a band saw including a foundation assembly adapted to attach to a table for the band saw. A translating layer assembly engages the foundation assembly and is permitted to move thereon. A carriage assembly is disposed on the translating layer, the carriage assembly further comprising a frame subassembly and a bulkhead subassembly, the frame subassembly further comprising an endwall adapted to support a left end of a workplace, and a front frame rail and back frame rail both connected to a frame leg to thereby slidably connect the frame subassembly to the translating layer. The bulkhead subassembly forms the other side of the carriage to secure the other end of the workpiece. Internal components within the bulkhead motorize the bulkhead, such that the workpiece can be turned and manipulated in two dimensions as the bandsaw blade cuts the rotating workpiece.

An embodiment of the invention provides a display panel, which includes a substrate having a pixel region and a peripheral region, a conducting layer overlying the substrate in the peripheral region, a first insulating layer overlying the conducting layer in the peripheral region, wherein a ratio between an area of the first insulating layer and an area of the conducting layer in the peripheral region is between about 0.27 and 0.99, a lower electrode layer overlying the first insulating layer, a second insulating layer overlying the lower electrode layer, and an upper electrode layer overlying the second insulating layer.

The organic light emitting display device includes an organic light emitting display panel and a data driver, wherein the organic light emitting display panel includes an active region which includes pixel driving TFTs for embodying an image and organic luminescent elements respectively connected with the pixel driving TFTs to emit light, a GIP region which includes a gate driver formed with a plurality of gate driving TFTs for respectively driving gate lines of the active region, a GND region formed between the GIP region and the active region to be formed with a base voltage line for supplying base voltage to the organic luminescent elements of the active region, and a sealant region formed with a sealant for attaching an upper substrate to a lower substrate, and wherein the GND region includes out-gassing blocking holes.

An electron emission element (1) includes an electrode substrate (2) and a thin film electrode (3), and emits electrons from the thin film electrode (3) by voltage application across the electrode substrate (2) and the thin film electrode (3). An electron accelerating layer (4) containing at least insulating fine particles (5) is provided between the electrode substrate (2) and the thin film electrode (3). The electrode substrate (2) has a convexoconcave surface. The thin film electrode (3) has openings (6) above convex parts of the electrode substrate (2).

Magnetically adjusting color-converting particles within a matrix and associated devices, systems, and methods are disclosed herein. A magnetic-adjustment process can include applying a magnetic field to a mixture including a non-solid matrix and a plurality of color-converting particles (e.g. magnetically anisotropic color-converting particles). The magnetic field can cause the plurality of color-converting particles to move into a generally non-random alignment (e.g., a generally non-random magnetic alignment and/or a generally non-random shape alignment) within the non-solid matrix. The non-solid matrix then can be solidified to form a solid matrix. A magnetic-adjustment process can be performed in conjunction with testing and/or product binning of solid-state radiation transducer devices. For example, a position, direction, strength, or duration of a magnetic field used to perform a magnetic-adjustment process can be controlled according to optical output collected from a solid-state radiation transducer device. Measuring the optical output and performing the magnetic-adjustment process can be at least partially concurrent.

A method of manufacturing a flexible display device includes: forming a soft substrate on a carrier substrate; forming a thin film layer comprising a display region on the soft substrate; removing a thin film layer excess portion of the thin film layer beyond an edge of the soft substrate; and separating the soft substrate and the carrier substrate.

An organic light emitting display resulting in an improved aperture ratio and a manufacturing method thereof. The organic light emitting display that includes a plurality of pixels arranged between first and second substrates, each of said pixels includes a plurality of thin film transistors, an organic light emitting diode, and a capacitor. The thin film transistors and the organic light emitting diode are formed on the first substrate and the capacitor is formed on the second substrate, and the thin film transistors and the capacitor are electrically connected with each other upon the first substrate being bonded to the second substrate.

Compounds (including polymers) for use in hybrid host materials which can be used in electroluminescent devices. The compounds comprise at least one electron-transporting moiety and at least one hole-transporting moiety which are joined by a flexible linker. Hybrid host materials comprising the compounds exhibit stability against phase separation, elevated glass transition temperature, morphological stability against crystallization, and isolation of the electron transporting moiety and hole transporting moiety π-systems.

The organic electroluminescence display device has a laminated portion on a base substrate. The device may have a cavernous portion formed by exploding a part of the laminated portion in a screening processing. A protective layer is formed to cover a whole surface of a wall defining the cavernous portion. Therefore, substances contained in the air are prevented from contacting to an organic electroluminescence layer at least partially defining the cavernous portion. Therefore, even if moisture is contained in the air, it is possible to prevent moisture from being absorbed by the organic electroluminescence layer. Moreover, since moisture is not absorbed by the organic electroluminescence layer, it is possible to reduce irregular spot on the device. In addition, it is possible to reduce a short circuit at an open defective portion.

An organic light emitting display panel includes a substrate, an organic light emitting diode disposed on a first side of the substrate, and a first light scattering layer disposed on a second side of the substrate opposite to the first side of the substrate, where the first light scattering layer includes a transparent thin layer including an indium, and a plurality of first micro-lenses is disposed on a plasma-treated side of the first light scattering layer.

To form stabilized organic light-emitting medium layers using the relief printing method and to provide an organic EL element excellent in terms of pattern-forming accuracy, film thickness uniformity and light-emitting characteristics, a substrate 2, first electrode layers 3 provided on the substrate 2, organic light-emitting medium layers 5 which are provided on the first electrode layers 3 and emit light when electrically connected, and second electrodes 6 which are provided on the organic light-emitting medium layers 5 and make the organic light-emitting medium layers 5 electrically connected when voltage is applied between the first electrodes 3 and the second electrodes are provided. In addition, at least one of the organic light-emitting medium layers 5 is formed of a mixture containing a polymer material having a weight-average molecular weight in a range of 1.5 million to 25 million and at least one low molecular material having a non-repetitive structure. Also, the mixing ratio between the polymer material and the low molecular material is set in a range of 0.05:1 to 0.5:1 in terms of weight ratio.

A display device includes a laminated wiring formed of a low-resistance conductive film, and a low-reflection film mainly containing Al and functioning as an antireflective film which are sequentially arranged on a transparent substrate, a wiring terminal part provided at an end part of the laminated wiring and has the same laminated structure as that of the laminated wiring, and an insulating film for covering the laminated wiring and the wiring terminal part, in which the insulating film side serves as a display surface side, the wiring terminal part has a first opening part penetrating the insulating film and the low-reflection film and reaching the low-resistance conductive film, and an outer peripheral portion of the first opening part has a laminated structure of the low-resistance conductive film, the low-reflection film, and the insulating film, in at least one part.

An LED assembly includes a rail device, an LED carrier with multiple LEDs securely mounted on the LED carrier and a wire extended out of the LED carrier from providing electricity to the LEDs and a plug device provided to two distal ends of the LED carrier and sandwiched in the rail device. The plug device has a passage defined in one distal end thereof to allow the wire to extend out of the plug device and a positioning seat is sandwiched in the rail device and provided to two sides of the plug device and has a receiving space to respectively and securely accommodate therein sides of the plug device.

A method of manufacturing a display panel of an organic light emitting display device includes determining a plurality of pixel groups, the pixel groups corresponding to groups of pixels of the display panel, calculating aperture ratios for the pixels, respective aperture ratios being calculated by pixel group based on respective distances between a power unit and the pixel groups, and forming the pixels of the display panel to have the respective aperture ratios according to the corresponding pixel groups.

A double-side light emitting display panel includes a substrate, a plurality of top emission pixel structures and a plurality of bottom emission pixel structures. The top emission pixel structures are disposed on the substrate, and the bottom emission pixel structures are disposed on the substrate. The top emission pixel structures and the bottom emission pixel structures are arranged alternatively on the substrate.

A self-light emitting display unit capable of improving manufacturing yield is provided. Sizes of color pixel circuits corresponding to pixels for R, G, and B are respectively set unevenly within a pixel circuit according to a magnitude ratio of drive currents which allow color self-light emitting elements in the pixel to emit with a same light emission luminance. Thereby, the pattern densities of color pixel circuits respectively corresponding to the pixels for R, G, and B become even to each other, and the pattern defect rate as the whole pixel circuit is decreased.

A flexible display device including: a flexible substrate having a display area and a moisture absorption area at a surface; a display unit at the display area; a moisture absorption layer at the moisture absorption area; and a sealant along an edge of the display area and configured to seal the moisture absorption layer and the display unit. The flexible substrate is configured to be folded at least one time, and the display area and the moisture absorption area are opposite to each other.

A high-pressure discharge lamp having an arc tube with a casing made of glass. The arc tube includes a light-emitting part and sealing parts connected to the light-emitting part. A pair of electrode rods are disposed within the glass casing such that their tips face each other with a gap therebetween and project into the discharge space, and their base ends are embedded in the sealing parts and overlap surfaces of metal foils provided in the sealing parts. Each base end is coated with a coating foil made of metal and having a C-like cross section with a slit formed between edges thereof. An end of the coating foil farthest from the light-emitting part is located closer to the light-emitting part than an end of the metal foil closest to the light-emitting part.

A light-emitting element which emits light with high luminance and can be driven at low voltage. The light-emitting element includes n (n is a natural number of 2 or more) EL layers between an anode and a cathode, and includes a first layer, a second layer, and a third layer between an m-th (m is a natural number, 1≦m≦n−1) EL layer from the anode and an (m+1)th EL layer. The first layer functions as a charge-generation region, has hole-transport properties, and contains an acceptor substance. The third layer has electron-transport properties and contains an alkali metal or the like. The second layer formed of a metal complex having a metal-oxygen bond and an aromatic ligand is provided between the first and third layers, whereby an injection barrier at the time of injecting electrons generated in the first layer into the m-th EL layer through the third layer can be lowered.

An inductively coupled plasma charged particle source for focused ion beam systems includes a plasma reaction chamber with a removably attached source electrode. A fastening mechanism connects the source electrode with the plasma reaction chamber and allows for a heat-conductive, vacuum seal to form. With a removable source electrode, improved serviceability and reuse of the plasma source tube are now possible.

A display device includes a circuit layer including: a plurality of transistors; a plurality of metal layers; and a plurality of wirings. The display device includes a display layer including first, second and third light emitting elements. The first light emitting element includes a first anode electrode and a first light emitting layer, a surface of the first anode electrode having a first surface contour structure; the second light emitting element includes a second anode electrode and a second light emitting layer, a surface of the second anode electrode having a second surface contour structure which is different from the first surface contour structure; and the third light emitting element includes a third anode electrode and a third light emitting layer, a surface of the third anode electrode having a third surface contour structure which is different from the second surface contour structure.

A spark plug includes a center electrode, a ceramic insulator provided with an axial hole, a metal shell, and a ground electrode having a facing surface that faces a leading end surface of the center electrode. An annular space is formed between an outer peripheral surface of the center electrode and an inner peripheral surface of the axial hole and is opened toward a leading end side, and when C (mm) is a distance between the outer peripheral surface of the center electrode and the inner peripheral surface of the axial hole in the opening of the annular space, C≧0.2 mm is satisfied. In a cross-section which includes the axial line and is orthogonal to the center axis of the ground electrode, a contour line of lateral surfaces of the ground electrode has a curved shape convexed outward.