Projectile part forming a small toy to be thrown by hand

Abstract

Projectile part (1) intended to be thrown by a user's fingers, the projectile part being in the form of a small plate with an outer contour, in which part there are provided a proximal bearing zone (ZAP) intended to receive the pad of a proximal phalanx of the index finger, a distal bearing zone (ZAD) intended to bear on the distal phalanx of the index finger, the proximal bearing zone (ZAP) comprising at least one rear proximal protuberance (31), the projectile part comprising a through-orifice (2) arranged at a distance from the proximal bearing zone, said orifice having an orifice contour with a front portion forming an intermediate bearing zone (ZAI), and intended to receive a propulsion force produced by the nail of the thumb, and a rear portion intended to receive the tip of the thumb. Method for throwing such a part.

Description

[0001] The present invention generally relates to parts forming small toys to be thrown manually. The focus here is on projectile parts to be thrown by the fingers of a user of said toy. Background and Prior Art

[0002] Small throwing toys of the type in question are known from documents FR2792537, US2012058703 or WO2005097284.

[0003] Document JP2003079970A discloses a projectile part intended to be projected by means of the thumb and a digital support of a hand of a user, said projectile part being in the form of a plate having a thickness of between 0.3 mm and 5 mm. said projectile part being delimited by an outer contour, the latter comprising a front edge on the side of the projection direction, a rear edge on the opposite side, a proximal edge and a distal edge.

[0004] A need arose to offer another solution with a different throwing experience. Statement of the invention

[0005] For this purpose, a projectile part is therefore proposed intended to be projected by means of the thumb and a digital support (mobilizing the index and / or middle finger, without excluding the ring finger) of a user's hand, said projectile part being in the form of a plate having a thickness of between 0.3 mm and 5 mm and preferably between 1 mm and 2 mm, said projectile part being delimited by an external contour, the latter comprising a front edge on the side of the projection direction and a rear edge on the opposite side, a proximal edge and a distal edge, characterized in that a proximal support zone (ZAP) is provided intended to receive at least one phalanx of the digital support, a distal support zone (ZAD) intended to come to bear on at least one other phalanx of the digital support, the proximal support zone (ZAP) comprising at least one rear proximal protuberance, and in that said projectile part comprises a through orifice (2) arranged at a distance from the proximal edge, said orifice having an orifice contour with a front portion (20) forming an intermediate support zone (ZAI) intended to receive a propulsion force formed by a pressure of the thumbnail,and a rear portion (24) intended to receive the tip of the thumb, and in that a longitudinal axis (X1) is defined extending between a proximal reference point (PrZp) of the proximal support zone (ZAP) and a distal reference point (PrZd) of the distal support zone, the projectile part having a reference length noted Lzz taken along said longitudinal axis, and the through-orifice having, along the longitudinal axis (X1), an overall dimension noted Lox, whereby a first dimensional ratio RD1 = Lox / Lzz is defined, which first dimensional ratio RD1 is greater than 25%, and in that the through-orifice has an orifice width (L21) along a transverse orifice direction, called the first orifice axis (A1), the through-orifice being separated from the distal edge by an escape band (4), the escape band having a minimum width (E4) which is less than the orifice width (L21),and in that said projectile part is such that the mass of the projectile part is less than 7 grams, and the reference length Lzz is less than 49 mm, so that the user can, according to an example of throwing, place the projectile part on his index finger and / or his middle finger with the tip of the thumb inserted in the orifice, then by pushing the thumb forward, exert a tension bandage thanks to the proximal support zone and the distal support zone, and beyond a predetermined tension threshold, the distal support zone is released and the projectile part is then projected forward with a concomitant rotational movement, the rotational movement being imparted by the retaining effect on the side of the proximal support zone.

[0006] Thanks to these arrangements, the projection of the projectile piece forward, accompanied by a simultaneous rotational movement of the axis perpendicular to a general plane of the plate, most often substantially vertical for a flat throw (at least at the start of the race) makes it possible to obtain a particularly advantageous radius of action. The rotational movement and the associated gyroscopic effect make it possible to obtain a stable and fairly linear trajectory (at least at the start of the race). After a few throws, precise and repeatable throws can be made.

[0007] It is noted that in the support zones, portions which are located on the edges of the projectile part are included; but for the proximal and distal support zones, the support zones also include lower surfaces as well as the edges connecting the lower surfaces to the edge. Regarding the intermediate support zone, it also includes the upper surface as well as the edges connecting the upper surface to the edge.

[0008] The projectile is light enough to be propelled several meters by thumb power alone.

[0009] The projectile part is small enough to be interposed between two phalanges of the same finger, i.e. straddling two phalanges.

[0010] The size and shape of the through hole are particularly suitable for receiving the insertion of the tip of the thumb with the nail resting on the front portion.

[0011] Note that the rear portion of the hole intended to receive the tip of the thumb forms a stop for the fleshy part of the end of the thumb.

[0012] In this document, the term "digital support" refers to one or more internal areas of the fingers, namely either the index finger or the middle finger or both, without excluding the ring finger. In practice, the "digital support" includes areas of the palmar surface of one or more of the aforementioned fingers.

[0013] In this document, the term "wafer" should be understood in a broad sense. The wafer considered here is not necessarily flat and does not necessarily extend in a plane, the front and back faces are not necessarily parallel to each other or flat.

[0014] The length noted Lzz taken along the longitudinal axis X1 can typically be the distance between the proximal reference point (PrZp) and the distal reference point (PrZd).

[0015] It should be noted that the qualifier 'digital' in the term digital support is related to fingers and not to digital signals or computer entities.

[0016] According to an advantageous aspect, the proximal support zone (PAZ) is such that the edge of the part at this location is generally concave. Such a shape naturally fits the pulp of the finger and this provides a certain retention effect on the proximal side.

[0017] According to an advantageous aspect, the proximal support zone (PAZ) is such that the edge of the part at this location has a concave part. Such a shape naturally fits the pulp of the finger and this provides a certain retention effect on the proximal side.

[0018] In various embodiments of the invention, one and / or the other of the following arrangements may optionally be used, taken alone or in combination.

[0019] According to an interesting option, the plate can have a substantially constant thickness. This provides ease of manufacture and right / left reversibility by simply turning the projectile part over.

[0020] Alternatively, the mass of the projectile can be less than 2 grams. Alternatively, the mass of the projectile can be less than 1 gram. This allows for long throws, even for children's hands.

[0021] As an option, the reference length Lzz of the projectile part can be less than 45 mm. This makes the projectile part easy to place. In addition, the projectile part is compact and one or more projectile parts can be stored in a small volume.

[0022] According to one option, the reference length Lzz can be less than 40mm, or even less than 35mm.

[0023] According to one option, the first dimensional ratio RD1 can be between 30% and 90%.

[0024] According to one option, the first dimensional ratio RD1 can be between 45% and 75%.

[0025] According to one option, a second dimensional ratio is defined RD2 = E4 / L21, where E4 is the minimum width of the exhaust band and L21 the orifice width along the first orifice axis (A1), the second dimensional ratio RD2 being between 10% and 60%.

[0026] According to one option, the minimum width (E4) of the exhaust band is such that the second dimensional ratio RD2 can be between 10% and 50%. According to a particular solution, the second dimensional ratio RD2 can be between 10% and 40%.

[0027] As an option, the minimum width (E4) of the exhaust band can be between 2 mm and 6 mm.

[0028] This is a compromise between the overall size of the projectile part and the position of the thumb hole. The position of the through hole is thus far from the proximal support zone, at an optimal distance, while maintaining a sufficient strip of material on the distal side so that the robustness of the part is correct and the integrity of the product is preserved, under the forces of throwing or stacking and storage. When throwing, we seek a balance between linear speed and rotation rate of the projectile part.

[0029] According to one option, we define for the external contour of the projectile part and the surrounded surface, an isoperimetric quotient equal to Q1 = [4π x Area1 / Perim 2< ], Perim representing the perimeter of the outer contour and Area 1 representing the surface enclosed by the outer contour, and the projectile part is such that Q1 is greater than 0.6.

[0030] Depending on an option Q1 can be between 0.7 and 0.9.

[0031] According to one option, we can define for the external contour of the projectile part and the surrounded surface, a second quotient noted Q2, with Q2 = ECI / Area1, where Area 1 represents the area enclosed by the outer contour and ECI represents the area of ​​the largest disc (PDI) inscribed inside the outer contour. According to one option, Q2 may be greater than 0.5.

[0032] According to one option, the largest dimension (Lmax) of the projectile part is less than 60 mm, preferably less than 50 mm and even more preferably less than 40 mm.

[0033] According to one option, the through hole (2) may have a height (L22) along a second hole axis (A2) perpendicular to the first hole axis, and the height is smaller than the width. In other words L22 < L21.

[0034] As an option, the height of the through hole can be less than 75% of its width. In other words, L22 < 0.75 L21.

[0035] We can also choose L22 between 50% and 70% of L21.

[0036] Alternatively, the through hole (2) may have an elliptical shape. An oval, ovoid or even circular shape is also considered.

[0037] According to one option, the front portion of the orifice can be formed in an arc of a circle with a first radius of curvature (R1) and the rear portion (24) of the through orifice (2) can have a second radius of curvature (R2), and the first radius of curvature (R1) is larger than the second radius of curvature.

[0038] According to one option, the front portion of the orifice can be concave and formed in an arc of a circle with a first radius of curvature (R1) and the rear portion (24) of the through orifice (2) can be concave, with a second radius of curvature (R2), and the first radius of curvature (R1) is larger than the second radius of curvature.

[0039] As an option, the first radius of curvature can be greater than 14 mm, the edge can be concave or convex.

[0040] As an option, the second radius of curvature (R2) can be between 6 mm and 14 mm.

[0041] Alternatively, the orifice contour is a closed contour. This provides strength and a valuable aesthetic appearance, unlike a contour interrupted by a notch.

[0042] According to one option, the distal support zone (DSP) may comprise a distal protrusion (32) forming a support on a distal phalanx of the digital support. This forms a tactile marker; this allows easier control of the dosage of effort on the distal side.

[0043] According to the invention, the proximal support zone (ZAP) comprises at least one front proximal protrusion (33). This forms a tactile marker; the projectile part can easily be installed in a posture straddling the fingertip.

[0044] According to the invention, the proximal support zone is such that the edge of the part at this location is generally concave between the rear proximal protuberance and the front proximal protuberance. Such a shape naturally fits the pulp of the finger, the two protuberances can be placed astride a finger.

[0045] Alternatively, the proximal support area can preferably be in an arc. Simple to manufacture, pleasing to the eye, practical to use, durable, natural shape. We choose a shape that naturally fits the fingertip.

[0046] According to one option, said radius of curvature (R3) can be between 0.5 cm and 25 cm.

[0047] According to one option, the intermediate support zone (IAZ) is interposed between the proximal support zone (PZ) and the distal support zone (DZ) in a substantially straight line arrangement. By means of which the through hole is arranged on the rear side of the projectile part and the useful propulsion stroke imparted by the thumb can be as long as possible.

[0048] According to one option, we locate the midpoint BPof the apexes of the proximal protuberances, and the shape of the part is such that the longitudinal axis X1, which passes through the proximal reference point (PrZp) of the proximal support zone and the distal reference point (PrZd) of the distal support zone, also passes substantially through the midpoint BP of the tips of the proximal protuberances.

[0049] From another reverse perspective, the proximal reference point (PrZp) can be defined as the intersection of the proximal edge with the line that connects the midpoint BP of the apexes of the proximal protrusions and the distal reference point (PrZd) or even the apex of the distal support zone (ZAD) when a distal protrusion exists.

[0050] According to one option, the projectile part is such that at least 70% of the surface of the through-hole (2) is located behind the longitudinal axis. Whereby the through-hole is arranged on the rear side of the projectile part and the useful propulsion stroke imparted by the thumb can be as long as possible.

[0051] According to one option, the center of mass (G) of the projectile part is located near the proximal end of the intermediate support zone (IAZ). Thus, the through orifice is generally located between the center of mass and the distal support zone, the orifice is distant from the proximal edge and offset from the center of mass to be able to impart the rotation on itself of the projectile part. An increase in rotation is advantageously obtained even after release of the IAZ, (see phase W4, figure 8 ).

[0052] According to one option, the projectile part can be formed by cutting from a substantially flat blank. It is noted that such an object can be inexpensive to manufacture, particularly in a context of mass production, or even in large series.

[0053] Alternatively, the projectile part may be formed from a substrate material coated with a decorative foil on the front side or the back side or both sides. Such a printed foil allows the appearance of the projectile part to be customized.

[0054] As an option, the projectile part can be obtained by casting.

[0055] As an option, the projectile part can be made of plastic.

[0056] Alternatively, the projectile part can be obtained by laser cutting and decoration, particularly of wood.

[0057] As an option, the projectile part can be curved, i.e. not flat.

[0058] Optionally, a raised relief can be provided on the projectile part, outside the plane of the plate. This can be a tactile mark or a shape that is part of an illustration or image printed on the face of the part with a 3D effect.

[0059] Alternatively, the outer contour can be continuous, without any singular points or sharp corners. This prevents the projectile from catching on clothing pockets.

[0060] Alternatively, the projectile part may be formed from a rigid paper or cardboard type material. The surface weight of the material forming the projectile part is between 400 g / m 2 and 5000 g / m 2 .

[0061] Alternatively, the surface weight may preferably be between 700 g / m 2 and 1500 g / m 2. This is an optimum with sufficient strength and optimum mass for use as a projectile.

[0062] Alternatively, the projectile part can be made of wood. It is possible to use chipboard or plywood.

[0063] According to one option, the first orifice axis (A1) is defined as the axis passing through the most distant points (P1,P2) of the contour of the through orifice.

[0064] The outer contour has a general longitudinal axis X1 which can be defined as extending between the midpoint BP of the tips of the proximal protuberances and the tip of the distal protuberance.

[0065] According to one option, the first orifice axis (A1) is oriented angularly relative to the longitudinal axis X1, whatever its definition variant, by an angle β between 0° and 35°, or even between 0° and 30°.

[0066] According to one option, the width of the hole L21 may be greater than 10 mm and preferably between 12 mm and 24 mm, or even preferably between 13 mm and 19 mm. The width must be sufficient to accommodate the tip of the thumb without any lateral pinching effect.

[0067] Alternatively, the height of the L22 hole may be between 5 mm and 15 mm, preferably between 7 mm and 13 mm. This provides a stop for the tip of the thumb and prevents excessive insertion and jamming of the thumb pad in the hole.

[0068] According to one option, the total area Area 1 occupied by the part (including the orifice area) can be between 6 cm 2< and 9 cm 2< , preferably between 6 cm 2< and 8 cm 2< .

[0069] According to one option, the surface of the orifice SF2 can be between 1 cm 2< and 2.5 cm 2< .

[0070] According to one option, a third dimensional ratio is defined RD3 = SF2 / Area1.According to one option, RD3 can be between 0.1 and 0.4. According to another option, RD3 can be between 0.15 and 0.25.

[0071] According to another aspect, the present invention also aims at a process for launching a projectile part in the form of a platelet with a thickness and an external contour, the latter comprising a front edge (11) on the side of the projection direction and a rear edge (12) on the opposite side, the projectile part comprising a proximal support zone (ZAP) intended to receive the pulp of a first phalanx of a digital support of a hand (M) of a user, a distal support zone (ZAD) intended to come to bear on another phalanx of a digital support, a through orifice (2) arranged at a distance from the proximal support zone, said orifice having an orifice contour with a front portion (20) forming an intermediate support zone (ZAI), the method comprising: / a / place the proximal support zone (ZAP) resting on at least one first phalanx of the digital support, / b / place the distal support zone (ZAD) resting on at least one other phalanx of the digital support, / c / place the thumb in the through hole (2) with the thumbnail resting on the intermediate support zone (ZAI), / d / exert an effort at least forward with the thumb while maintaining the digital support against the proximal and distal support zones (ZAP, ZAD), / e / allow a slide to occur (at least at the distal support zone (ZAD)) to cause the release of said distal support zone (W2) and the forward projection of the projectile part (W2, W3, W4), with simultaneous rotation induced by the delayed release of the proximal support zone (ZAP).

[0072] According to one option, the proximal support zone (PAZ) comprises at least one rear proximal protrusion (31), forming a rear retainer on the proximal side. This facilitates the positioning and launching of the projectile part.

[0073] According to one option, at step / d / , a balance of forces (PP, FRD, FRP) exerted on the projectile part is maintained, with a sum PP+FRD+FRP close to zero.

[0074] According to one option, the wafer has a slice, a front face and a back face, and the support zones, respectively proximal and distal (ZAP, ZAD), can extend over the slice and the back face as well as over the edges connecting the back face to the slice.

[0075] According to one option, the intermediate support zone (ISZ) extends along an edge connecting the front face to the edge. The nail is in oblique support, in point linear support.

[0076] According to one option, the intermediate support zone (ISZ) extends over the edge and the front face as well as over the edge connecting the front face to the edge.

[0077] According to one option, the method and the projectile part are such that the same projectile part can be launched either by a left hand or by a right hand of individuals, and in the case where the projectile part is devoid of symmetry with respect to a median plane PXZ, it is sufficient to turn the part over to pass from left hand to right hand or vice versa.

[0078] Other aspects, aims and advantages of the invention will appear on reading the following description of an embodiment of the invention, given by way of non-limiting example. The invention will also be better understood with reference to the attached drawings in which: there figure 1 illustrates, in plan view, a first embodiment of the object to be thrown ('projectile piece') according to the present invention, the figure 2 illustrates, in plan view, the projectile part to be launched from the figure 1 , there figure 3 illustrates, in plan view, a second embodiment of the projectile part to be launched, the figure 4 illustrates, in plan view, a third embodiment of the projectile part to be launched, the Figure 5 , available in figures 5A 5B 5C , shows respectively plan, longitudinal section and cross-section views, with the projectile part according to the first embodiment in the launching situation, the figure 6 illustrates, in perspective, the projectile part according to the first embodiment, the figure 7 , available in figures 7A 7B 7C 7D 7E 7F , shows views illustrating the throwing sequence for throwing the projectile piece according to the first embodiment. figure 8 illustrates a chronogram of the forces exerted and the speeds imparted in the process of throwing the projectile coin to be thrown. figure 9illustrates, in plan view, a fourth embodiment of the projectile part. figure 10 illustrates, in plan view, a fifth embodiment of the projectile part. figure 11 schematically illustrates an evolution of the propulsion effort during the throw. figure 12 illustrates in more detail an example of a through hole. figure 13 , available in figures 13A 13B , schematically illustrates the placement of the projectile piece on the digital support in preparation for the launch. figure 14 illustrates, in plan view, a sixth embodiment of the projectile part to be launched. figure 15 illustrates, in plan view, variants of realization highlighting certain dimensions of the projectile part to be launched. figure 16 illustrates, in plan view, a seventh embodiment of the projectile piece to be launched, with in addition a geometric construction based on the barycenters. figure 17schematically illustrates elements allowing the calculation of the second dimensional quotient Q2.

[0079] In the various figures, the same references designate identical or similar elements. For reasons of clarity of the presentation, certain elements may not be shown to scale.

[0080] In this document, the terms 'proximal' And 'distal' designate entities of the fingers respectively closer and less close to the palm of the hand. Concerning the projectile part, the term 'longitudinal direction' designates a direction generally passing through the support zones proximal And distal. A more precise definition can be given later.

[0081] In this document, the term 'Before' designates the direction in which the projectile is thrown or projected, and the term 'back' means the direction opposite to the forward direction.

[0082] As shown in the figures, a projectile part is presented 1 to throw by the fingers of one hand M of a user. It can be the right hand or the left hand.

[0083] For a given hand, we note by F0 the thumb, by F1 the index, and by F2 the middle finger. The term "digital support" refers to one or more internal areas of the fingers F1,F2 namely either the index finger or the middle finger or both. The ring finger can also participate in digital support.

[0084] The dorsal surfaces of the phalanges are not used except for the nail (or even the back) of the thumb F0. In practice, the digital support considered here uses the palmar side of the fingers. Generalities of form

[0085] In the illustrated examples, the projectile part 1 is presented as a plate having a thickness E1.Thickness may vary slightly. It is not excluded to have a protrusion outside the plane of the plate.

[0086] In embodiments of interest, the wafer has a thickness E1 substantially constant (cf. Fig 6 ).

[0087] Generally speaking, the general thickness E1 is between 0.3 mm and 5 mm.

[0088] In embodiments of interest, the overall thickness E1 is between 1 mm and 2 mm.

[0089] The projectile part 1 is delimited by an outer contour, the latter comprising a front edge 11 on the side of the projection direction and a rear edge 12 on the opposite side. To complete the contour, a proximal edge is provided 10 and a distal edge 13.

[0090] The projectile part 1consists of a front side and a back side connected to each other by an edge that forms the outline. By convention, the front side will be the side facing upwards when the projectile coin is thrown with the right hand.

[0091] So, the front side is the side facing upwards when the projectile part 1 is placed so that the rear proximal protrusion 31 (defined later) is located at the bottom right and the reverse side will be the side facing upwards when the projectile part 1 is placed so that the rear proximal protrusion 31 is located at the bottom left.

[0092] In embodiments of interest, the outer contour is continuous, without singular points or angular corners. The tangent evolves continuously, without jumps.

[0093] G denotes the center of mass of the projectile part.

[0094] We designate by G'the barycenter of the unpierced projectile part, namely the barycenter of the entire area surrounded by the outer contour of the projectile part. This barycenter is visible on the figures 2 And 16 the usefulness will be seen later.

[0095] In embodiments of interest, the projectile part 1 is formed by cutting from a substantially flat blank.

[0096] Alternatively, the projectile part 1 can be obtained by casting.

[0097] Alternatively, the projectile part 1 can be curved, i.e. not flat. In other words, there can be a more or less marked 3D effect in the shape of the projectile part.

[0098] In embodiments of interest, the projectile part is formed from a cardboard-like material.

[0099] In embodiments, the projectile part is formed from a plastic material.

[0100] Generally, the surface weight will typically be between 400 g / m 2< and 5000 g / m 2< .

[0101] In embodiments of interest, the surface weight is between 700 g / m 2 and 1500 g / m 2 .

[0102] Alternatively, the projectile part 1 may be formed from wood or a derived material. Alternatively, the projectile part 1 may be formed from any other material, leather, plant material, recycled material. The projectile part 1 may be formed from any plastic material.

[0103] Projectile part 1 includes a through hole 2 which will be described in detail later.

[0104] The projectile part 1 comprises a proximal support zone (ZAP) intended to receive at least one phalanx of the digital support, a distal support zone (ZAD) intended to come into contact with at least one other phalanx of the digital support.

[0105] The proximal support zone ZAPmay contact the proximal or intermediate phalanx of the index finger F1 or the proximal or intermediate phalanx of the middle finger F2 or several of the aforementioned phalanges at the same time.

[0106] The proximal support zone ZAP includes portions that are located on the edge of the projectile part but also includes lower surfaces (back side for right-handed throwing) as well as the edges connecting the lower surfaces to the edge.

[0107] Advantageously, the proximal support zone ZAP includes at least one rear proximal protrusion 31.

[0108] By 'protuberance', here we mean a bump (or a projection or even an outgrowth) extending in the plane of the part. Geometrically, the protuberance is characterized by a local maximum distance in reference to the center of mass G. The local maximum is called the summit S1 (cf Figures 1 And 2). For example, the protuberance has an additional distance from G of between 2% and 20%, more preferably for example between 4% and 12%. According to another perspective, the protuberance protrudes radially outwards compared to the neighboring zones located tangentially on either side of said protuberance.

[0109] Furthermore, it should be noted that protrusion also includes a projecting shape that protrudes above the front plane or below the back plane of the plate.

[0110] The rear proximal protuberance 31 provides a holding effect during the throwing process as we will see later.

[0111] The distal support zone ZAD may contact the distal or intermediate phalanx of the index finger F1 or the distal or intermediate phalanx of the middle finger F2 or several of the aforementioned phalanges at the same time.

[0112] The distal support zone ZADincludes portions that are located on the edge of the projectile part but also includes lower surfaces (back side for right-handed throwing) as well as the edges connecting the lower surfaces to the edge.

[0113] We define a proximal reference point PrZp on the proximal edge 10 which forms the proximal support zone ZAP. A distal reference point is defined PrZd on the distal edge 13 of the distal support zone. We define a longitudinal axis X1 which extends between the proximal reference point PrZp and the distal reference point PrZd. According to the said longitudinal axis X1, the projectile part has a reference length noted Lzz.

[0114] The positions of the proximal reference points PrZp and distal PrZd are defined according to the considered variants of the projectile part.

[0115] In practice we note that the distal support zone ZAD covers a few millimeters on either side of the X1 axis and extends a little further forward than backward.

[0116] Generally we will take as the direction of the longitudinal axis X1 a direction perpendicular to the front-back direction, and parallel to a general proximal-distal orientation. And in the absence of other geometric marks which will be seen later, with reference for example to the figure 4 , we can choose the proximal reference points PrZp and distal PrZd as the intersections of the longitudinal axis X1 with the respective proximal and distal edges, for a longitudinal axis X1 spaced from the rear edge 12 from a distance L12b 12.5 mm.

[0117] We will see later, in relation to the barycenters, an alternative definition for determining the proximal reference points PrZpand distal PrZd, and the axis X1.

[0118] The reference length Lzz separates the proximal reference points PrZp and distal PrZd. The reference length Lzz is less than 49 mm. According to one embodiment, the reference length Lzz can be less than 45mm, or even less than 40mm, or even less than 35mm. The projectile part is thus easy to place on the digital support. The reference length Lzz is preferably greater than 20 mm. An optimum can be chosen at 27 mm.

[0119] In embodiments of interest, the support area distal (ZAD) may include a distal protrusion 32. The distal protuberance 32 has a noted summit S2.

[0120] The distal protuberance 32 forms a support on a distal or intermediate phalanx of the digital support. The distal protuberance 32provides a holding effect during the throwing process as will be seen later. The distal protrusion 32 forms a tactile marker and allows for easier dosage of effort.

[0121] The distal protrusion 32, by the small restraining effect it provides, allows a greater accumulation of potential energy before stalling (i.e. the transition from static friction to dynamic friction). Greater potential energy allows greater acceleration. In addition, a short distal protrusion 32 will reduce the friction distance and time so as to minimize the energy loss caused by dynamic friction following stalling.

[0122] The distal protuberance 32 forms an excess of E2 relative to a primitive circle or a polynomial curve of order 2 generally inscribed on the distal edge. E2is preferably between 0.25 mm and 3 mm. In a particular mode, the overhang E2 is close to 1 mm.

[0123] For positioning the distal reference point PrZd we ignore the protuberance 32 and the distal reference point PrZd is slightly recessed (from E2) inwards relative to the distal edge 13 of the distal support zone (visible at figures 1-3 , 9 , 10 And 14 ). To ignore the protuberance 32, we use an arc of a circle inscribed on the central zone of the distal edge as illustrated in dotted lines in the figures.

[0124] In embodiments of interest, the proximal bearing area ZAP includes a front proximal protrusion 33, functionally complementary to the rear proximal protuberance 31. The front proximal protuberance 33has a noted summit S3.

[0125] The two protrusions form a good tactile landmark; the proximal edge is placed astride the fingertip.

[0126] The proximal bearing area may be such that the edge of the part at this location, i.e. the proximal edge, is generally concave between the rear proximal protrusion 31 and the front proximal protrusion 33. The proximal edge may be arc-shaped.

[0127] Any generally concave shape can be suitable. The radius of curvature R3 is not necessarily constant but can vary R3'. For example, you can choose radii between 1 cm and 10 cm without this being limiting.

[0128] We define a proximal midpoint BP, forming the middle of the apexes of the proximal protuberances S1,S3.

[0129] Under these conditions, the general longitudinal axis is defined for the projectile part and its external contour. X1 as extending between the middle BP of the tips of the proximal protuberances S1,S3 and the summit S2 of the distal protuberance.

[0130] The proximal reference point PrZp is then at the intersection of the longitudinal axis X1 with the proximal edge.

[0131] On the figure 3 , on the variant shown, there is no front protuberance on the proximal side.

[0132] On the figure 4 , in the variant shown, there is no protuberance on the distal side and there is no front protuberance on the proximal side.

[0133] Regarding other dimensions appearing in the figures, L10 = Lzz + distance (BP-PrZp); L11 = overall dimension according to X1, in practice between Lzz and Lzz + 5mm.

[0134] In reference to the figures 1-4, 9 , 10 , 14 , for dimensions in the front-back direction, in a special case, L12a is chosen in an interval [12mm - 20mm], or even in an interval [12mm - 15mm]. In a particular case, L12b is chosen in an interval [12mm - 15mm].

[0135] In a particular case, their sum L12 is chosen in an interval [24mm - 35mm] or even in an interval [25mm - 30mm].

[0136] In a particular case, the outer contour may have a front-back symmetry, namely a symmetry with respect to the X1-Z plane.

[0137] Generally, the mass of the projectile part is less than 7 grams. In preferred embodiments the mass of the projectile part is less than 5 grams.

[0138] Preferably, the mass of the projectile part may be less than 2 grams. According to a preferred option, the mass of the projectile part may be less than 1 gram.

[0139] The largest dimension of the projectile part is noted Lmax (see Lmax'). (cf figures 2 , 3,4 ).

[0140] Generally speaking, Lmax < 60 mm. Preferably Lmax will be less than 50 mm, or even less than 40 mm.

[0141] As illustrated in figures 14 And 15 , the front edge 11 is free of shape, the front edge 11 can have wavy and various shapes, more or less protruding towards the front. This allows the projectile piece to be personalized and made to resemble the silhouette of a known object or character.

[0142] For the external contour of the projectile part, we define an isoperimetric quotient equal to Q1 = [4π x Area1 / Perim 2< ], where Perim represents the perimeter of the outer contour (which is squared in the formula) and where Area 1 represents the area enclosed by the outer contour.

[0143] The projectile part is such that Q1 is greater than 0.6.

[0144] According to one achievement, Q1 can be between 0.7 and 0.9.

[0145] Furthermore, we define a second quotient noted Q2. In reference to the figure 17 , we define a particular disk as the largest disk PDI inscribed inside the outer contour of the projectile. The surface of this larger inscribed disc is noted ECI. Area 1 represents the total surface area surrounded by the outer contour (part not pierced with a hole).

[0146] The second quotient Q2 expresses itself through Q2 = ECI / Area1. In achievements of interest, Q2 can be greater than 0.5. In preferred modes, one can haveQ2 can be between 0.6 and 0.85.

[0147] We define a fourth quotient Q4 expresses itself through Q4 = ECITR / AireTR1. ECITR is the area of ​​the largest inscribed disk, truncated as explained below for AreaTR1. AireTR1 represents an area truncated along the line U3 ( Fig. 16 ), namely the total surface area surrounded by the outer contour (part not pierced with an orifice) from which anything protruding more than 12.5 mm forwards from the axis is removed X1 (ie Area 1 from which we remove everything that protrudes more than 12.5 mm forwards in relation to the axis X1 ).

[0148] In achievements of interest, Q4 can be greater than 0.5. In preferred modes one can have Q4 can be between 0.6 and 0.85.

[0149] We can consider that Q1, Q2 And Q4are characteristic of the form factors of the projectile part. Through hole

[0150] The through hole 2 is arranged at a distance from the proximal support zone which makes it possible to impart a rotational torque (reference CR, fig 5A ) in a clockwise direction (seen from above, right hand).

[0151] The through hole has a hole outline with a front portion 20 and a rear portion 24. The front portion 20 forms an intermediate support zone (ISZ) intended to receive a propulsion force formed by support from the flat of the thumbnail F0 . The rear portion 24 is intended to receive the tip of the thumb, as illustrated in particular in figure 11 .

[0152] The rear portion 24 stop shape for the tip of the thumb, it prevents the thumb from sinking too far into the through hole 2. Note that the thumb F0must be pushed in far enough to be able to apply a propulsive force over a sufficient stroke, but not so far that at the end of the movement (i.e. after PP3 Fig. 11 and during W3 cf Fig. 8 ) the thumb can quickly and easily escape from the through hole 2 so that its pulp does not slow down the projectile part. This allows powerful and fast throws, without snagging.

[0153] The intermediate support zone includes the edge of the front portion. It can also include the upper surface as well as the edge 27 or the edges connecting the top surface to the edge.

[0154] In embodiments of interest, the orifice contour is a closed contour, as illustrated in all figures except fig 10 .

[0155] However, it is not excluded to have a discontinuity as illustrated in the figure 10 . In this case, a notch 87extends between the rear edge and the through hole 2. The notch could be positioned towards the front edge or elsewhere.

[0156] In embodiments of interest, the first orifice axis may be defined as A1 the axis passing through the most distant points ( P1,P2 ) of the outline of the through hole. We then define a second hole axis A2 perpendicular to the first orifice axis.

[0157] The first point P1 is the proximal corner of the orifice 2.

[0158] The second point P2 is the distal corner of the orifice 2.

[0159] The front portion 20 presents a summit 25, the point furthest from the first axis A1.

[0160] The rear portion 24 presents a summit 26, the point furthest from the first axis A1.

[0161] According to one embodiment, the center of mass is located in the vicinity of the first point P1. According to one embodiment, the distance between the center of mass and the first point P1 is less than 5 mm.

[0162] As shown in the figures, the first orifice axis A1 is angularly oriented to the longitudinal axis at an angle β relative to the general longitudinal axis X1 According to one embodiment, the angle β between 0° and 35°, or even between 0° and 30°.

[0163] According to another embodiment, the angle β between 0° and 20°.

[0164] We note for example that on the figure 4 , the angle β is smaller than the one shown in the figure 3 .

[0165] The through hole 2 has a noted orifice width L21 along the transverse direction of the orifice, i.e. along the first orifice axis A1.

[0166] The through hole 2 has a height noted L22 along the second orifice axis A2. In the figures, the height is the distance between the two vertices (front 25 and rear 26) of the orifice 2.

[0167] Generally speaking, height is smaller than width. In other words, L22 < L21. The height L22 is such that the rear edge 24 forms a stop for the tip of the thumb and prevents excessive insertion and jamming of the thumb pad in the hole 2.

[0168] In some embodiments of interest, the height of the through hole may be less than 75% of its width. In other words L22 < 0.75 x L21. We can choose an interval such as 0.45 x L21 < L22 < 0.75 x L21.

[0169] The through hole 2 is separated from the distal edge by a strip of material called the escape strip and marked 4.The exhaust band has a minimum width noted E4, and is delimited towards the outside by the exhaust curve and marked 14.

[0170] If we follow the exhaust strip along its path L4 (cf Fig 2 ), the width can change, we are interested in the narrowest point which therefore presents the minimum width noted E4.

[0171] In a particular case, the exhaust band has a curved outer edge, substantially concentric with the local contour of the orifice. More precisely, the radius of curvature R4 of the outer edge and the radius of curvature R5 of the inner edge of the facing orifice have neighboring reference points. In this case, the width of the exhaust band 4 is substantially constant on the L4 route.

[0172] Note that the minimum width noted E4 is less than the orifice width L21.In some interesting realizations, the minimum width E4 is less than 75% of the orifice width L21. In other embodiments of interest, the minimum width E4 is less than 50% of the orifice width L21. In other embodiments of interest, the minimum width E4 is less than 6 mm. In other embodiments of interest, the minimum width E4 is less than 5 mm. The protrusion 32 is excluded from the preceding dimensional considerations.

[0173] We define a second dimensional ratio RD2 = E4 / L21, where E4 is the minimum width of the exhaust band and L21 the orifice width along the first orifice axis (A1), the second dimensional ratio RD2 being between 10% and 60%.

[0174] In some embodiments of interest, the second dimensional ratio RD2can be between 10% and 50%. Depending on a particular solution, the second dimensional ratio RD2 can be between 10% and 40%.

[0175] In some achievements of interest, illustrated using the figure 12 , the front portion 20 of the orifice is concave and formed in an arc of a circle with a first radius of curvature R1, the dotted line marked 20' denotes one variant among an infinite number of possibilities.

[0176] The rear portion 24 of the through hole 2 can be concave, with a second radius of curvature R2. The first radius of curvature R1 is greater than the second radius of curvature R2.

[0177] In some embodiments, the first radius of curvature R1 may be greater than 10 mm.

[0178] In some embodiments, the second radius of curvature R2 can be between 5 mm and 15 mm.

[0179] In a particular case of realization, illustrated in figure 14 , the orifice may have a circular shape. In this case L21=L22 represents the diameter.

[0180] On the figure 9 , on the variant shown, the curvature of the front portion 20 of the orifice is reversed. We therefore understand that the front portion 20 The opening of the hole can be concave or convex. It must receive the push of the thumbnail without the tip of the thumb being trapped, laterally or in the front-back direction. Alternative definition of the longitudinal axis X1

[0181] The through hole can be affected by its barycenter noted CC as visible to the figures 2 And 16 . This barycenter CC can be calculated as a virtual center of mass. Furthermore, we saw above that the real projectile part has a center of mass noted G.And a projectile without an orifice would have a center of mass denoted G'. It turns out that these three points are aligned.

[0182] We can draw a line that passes through the points CC And G (and incidentally G'), this line is noted U1. From there, we define a second straight line angularly spaced from U1 in a clockwise direction by an angle noted α. This second straight line is noted U2. This second right U2 comes to a tangent with the rear edge 12 of the projectile part. In the example illustrated the angle α is worth 45°.

[0183] Based on these elements, we can define the longitudinal axis X1, especially in the absence of protuberance(s) and other forms of marking. We can then choose for X1 a line parallel to the second line U2 and shifted forward by a distance L6. In practice we choose L6 such that L6=12.5 mm.

[0184] Although the default method has the values α =45° and L6=12.5 mm indicated, it could optionally for certain particular shapes, in particular those strongly advancing the front edge, be more relevant to take close values ​​such as 40° to 60° for α and 12 to 13 mm for L6.

[0185] The proximal reference point PrZp is then at the intersection of the longitudinal axis X1 with the proximal edge 10.

[0186] The distal reference point PrZd is then at the intersection of the longitudinal axis X1 with the distal edge 13.

[0187] Whereby, based on the barycenters CC and G, we can unambiguously define a longitudinal axis X 1 and derive the distal and proximal reference points from it.

[0188] Once the longitudinal axis X1 determined, the distance Lzzcan be determined as already explained above.

[0189] Other through hole shapes are also considered. For example as shown in the figure 15 , several through-hole variants are drawn, each having an overall length along the longitudinal axis marked respectively Lo1, Lo2, Lo3.

[0190] We note generically Lox the overall dimension along the longitudinal axis X1.

[0191] We define a first dimensional ratio RD1= Lox / Lzz, which first dimensional ratio RD1 is generally greater than 25%.

[0192] In some embodiments, the first dimensional ratio RD1 is between 30% and 90%.

[0193] In some embodiments, the first dimensional ratio RD1 is between 45% and 75%.

[0194] We note Area 1the total area occupied by the room (as already explained above). Area 1 can be between 5 cm 2< and 10 cm 2< , preferably between 6 cm 2< and 9 cm 2< .

[0195] We note SF2 the surface of the orifice. SF2 can be between 0.5 cm 2< and 3 cm 2< .

[0196] We define a third dimensional ratio RD3 = SF2 / Area 1.

[0197] In some embodiments, RD3 may be between 0.1 and 0.4. In some embodiments, RD3 may be between 0.15 and 0.25.

[0198] In some designs, at least 60% of the surface area SF2 of the through hole 2 is located behind the longitudinal axis X1.

[0199] In some embodiments, at least 70% of the surface area of ​​the through-hole 2 is located behind the longitudinal axis X1. Throwing process

[0200] According to a general description, the user places the projectile piece on their index and / or middle finger with the tip of the thumb inserted into the hole 2, then by pushing the thumb forward, the user exerts a tension bandage thanks to the proximal support zone ZAP and to the distal support zone ZAD, and beyond a predetermined tension threshold, the distal support zone is released and the projectile part is then projected forward with a concomitant rotational movement, the rotational movement being imparted by the restraint effect on the side of the proximal support zone.

[0201] More generally, we use a digital medium as already defined above. The launching process can be broken down as follows: / a / place the proximal support zone ZAP resting on at least one first phalanx of the digital support, / b / place the distal support zone ZADresting on at least one other phalanx of the digital support, / c / place the thumb F0 in the through hole 2 with the thumbnail resting on the intermediate support area ZAI.

[0202] Steps / a / , / b / , / c / can be carried out in any chronological order, i.e. different from the one above, and achieve the same result, which is: digital support in contact with ZAP and ZAD, thumbnail in contact with ZAI.

[0203] As illustrated in the figure 13 , pressing on the digital support can involve several parts of the pulp belonging to several phalanges.

[0204] We notice that the thumbnail is very inclined, almost horizontal. The thumb exerts a noticeable effort PP.

[0205] For steps / a / and / b / , the user can use the vertices S1,S2,S3 of the protrusions as a tactile and / or visual cue.

[0206] In reference to the figures 5 , 7 And 13 , we note that the projectile part is a little behind the index finger (or more generally the main supporting finger)

[0207] Especially the front edge 11 does not protrude or protrudes slightly forward of the index finger F1. Another possible reference: we can see the back of the index / middle finger through the through hole (2) (very visible on Fig. 7 )

[0208] We also note that the rear portion (24) protrudes towards the rear of the index finger F1 or major F2 (cf Fig. 7 ).

[0209] The reaction of the digital support provides a proximal reaction noted FRP and a distal reaction noted FRD. More precisely the reaction of the proximal support zone FRP is directed backwards and upwards (very little towards the distal area). Similarly the reaction of the distal support area FRDis directed backward and upward (very little towards the proximal area).

[0210] The effort PP exerted by the thumb is directed downwards (cf Figures 5B and 5C ).

[0211] The bandage consists of increasing the effort exerted by the thumb, during the identified phase W1 in figure 8 The reaction of the digital support increases concomitantly. The vector sum PP + FRP + FRD remains zero as long as the projectile part remains stationary before its release. This is (in tribology) a phase called static friction.

[0212] As illustrated in figure 11 , we see that the effort PP exerted by the thumb gradually moves towards the horizontal PP1, PP2, PP3. This is the marked step / d / : exert an effort at least forward with the thumb while maintaining the digital support against the proximal and distal support zones (ZAP, ZAD) which form a bridge on the digital support.

[0213] At a given moment, an imbalance of effort occurs with a thumb effort which exceeds the reaction of the support zones, with at least one resultant (or component) along the throwing axis Y1. A slide occurs at the distal support zone (ZAD) to cause the release of said distal support zone (W2) and the forward projection of the projectile part (W3, W4, and even W2), with simultaneous rotation induced by the restraint exerted by the proximal support zone ZAP.

[0214] When sliding occurs we speak of dynamic friction.

[0215] The previous step is noted / e / and consists in other words of allowing a slide to occur (at least at the level of the distal support zone (ZAD)) to cause the release of said distal support zone ( W2 ) and the forward projection of the projectile part ( W3,W4), with simultaneous rotation induced by the delayed release of the proximal support zone (PSZ).

[0216] On the figure 8 , the phase W1 represents the bandage, the phase W2 (moments T1 has T2 ) represents the distal release, the phase W3 (moments T2 has T3 ) represents the proximal release and the phase W4 (moments T3 has T4 ) is the end of the thumb push. The phase W5 represents the free flight of the projectile.

[0217] The linear velocity and rotational velocity reach their maximum at the instant T4. The time-delayed release of the distal and proximal zones causes the projectile part to rotate clockwise for a right-handed person and counterclockwise for a left-handed person.

[0218] The moment of inertia of the projectile part being low, the imbalance of force in the phase W3imparts significant rotation. Moreover, in the phases W3 And W4, the thumb thrust being offset from the center of gravity, we increase the rotation by the natural lever arm (distance G - summit 25 ).

[0219] As already mentioned, the center of mass G of the projectile part is located near the proximal end P1 of the intermediate support zone ZAI, a little inside the through hole, that is to say between the top 25 and the point P1. As visible on the figure 16 , the top of the front portion 20 and the center of mass G are separated by a distance L5. In practice L5 is located in the range between 4 mm and 10 mm.

[0220] This position shift allows an increase in rotation even after release of the proximal edge, (see phase W4, fig 8 ).

[0221] It should be noted that the presence of the protrusions mentioned above is favorable for the implementation of the throwing process.

[0222] THE Figures 7A and 7B illustrate an example of the placement of the projectile part on the digital support. The Figure 7C illustrates the situation with the thumb in place before the actual throw.

[0223] THE Figures 7D, 7E and 7F illustrate phases of the throw, the Figure 7F showing several successive positions of the projectile part.

[0224] It is noted that the projectile part as defined geometrically above is compatible with a propulsion force applied to an edge of the through-orifice by any finger of the user, i.e. not exclusively the thumb.

[0225] In some embodiments, the projectile part has only one hole of the size described above. It is not excluded that there are other holes of smaller size.

[0226] In some embodiments, the projectile part has only one orifice.

Claims

1. Projectile part (1), intended to be projected by means of the thumb and a digital support of a hand (M) of a user (U), - said projectile part presenting itself as a small plate having a thickness (E1) between 0.3 mm and 5 mm and preferably between 1 mm and 2 mm, said projectile part being delimited by an outer contour, the latter comprising a front edge (11) on the side of the projection direction, a rear edge (12) on the opposite side, a proximal edge (10) and a distal edge (13), - the projectile part being provided with a proximal bearing zone (ZAP) intended to receive at least one phalanx of the digital support, a distal bearing zone (ZAD) intended to bear on at least one other phalanx of the digital support, the proximal bearing zone (ZAP) comprising at least one rear proximal protrusion (31), - said projectile part comprising a through orifice (2) arranged away from the proximal edge, said orifice having an orifice contour with a front portion (20) forming an intermediate bearing zone (ZAI) and intended to receive a propulsion force formed by a bearing of the thumbnail, and a rear portion (24) intended to receive the tip of the thumb, - the projectile part defining a longitudinal axis (X1) extending between a proximal reference point (PrZp) of the proximal bearing zone (ZAP) and a distal reference point (PrZd) of the distal bearing zone, the projectile part having a reference length noted Lzz taken along said longitudinal axis, and the through orifice (2) having, along the longitudinal axis (X1), an overall dimension noted Lox, thanks to which a first dimensional ratio RD1 = Lox / Lzz is defined, which first dimensional ratio RD1 is greater than 25%, - the through orifice (2) having an orifice width (L21) along a transversal orifice direction, said first orifice axis (A1), - the through orifice (2) being separated from the distal edge by an escapement strip (4), the escapement strip having a minimum width (E4), which is less than the orifice width (L21), - the said projectile being such that the mass of the projectile is less than 7 grams, and the reference length noted Lzz is less than 49 mm, - the proximal bearing zone (ZAP) being such that the section of the part at this location comprises a concave part, and preferably the section of the part at this location is generally concave, - the proximal bearing zone (ZAP) comprises at least one front proximal protrusion (33) the part at this location is generally concave between the rear proximal protrusion (31) and the front proximal protrusion (33)2. Projectile part (1) according to claim 1, wherein a second dimensional ratio RD2 = E4 / L21 is defined, where E4 is the minimum width of the escapement strip and L21 is the orifice width along the first orifice axis (A1), the second dimensional ratio RD2 being between 10% and 60%.

3. Projectile part (1) according to one of claims 1 to 2, wherein the through orifice (2) has a height (L22) along a second orifice axis (A2) perpendicular to the first orifice axis, and wherein the height is smaller than the width, and preferably the height is smaller than 75% of the width.

4. Projectile part (1) according to one of claims 1 to 3, wherein the front portion of the orifice is arc of circle shaped with a first radius of curvature (R1) and the rear portion (24) of the through orifice (2) has a second radius of curvature (R2), and the first radius of curvature (R1) is larger than the second radius of curvature (R2).

5. Projectile part (1) according to one of claims 1 to 4, wherein the distal bearing zone (ZAD) comprises a distal protrusion (32) forming a bearing on a distal or intermediate phalanx of the digital support.

6. Projectile part (1) according to one of claims 1 to 5, the proximal bearing zone is such that the section of the part at this location is in an arc of circle.

7. Projectile part (1) according to one of claims 1 to 6, having a substantially constant thickness (E1), and / or wherein the projectile part is formed by cutting from a substantially flat blank, and / or the projectile part is formed from cardboard or plastic material, with a weight per unit area between 400 g / m2 and 5000 g / m2, preferably between 700 g / m2 and 1500 g / m2.

8. Projectile part (1) according to one of claims 1 to 7, wherein the first orifice axis (A1) is defined as the axis passing through the furthest points (P1, P2) of the contour of the through orifice, and the first orifice axis (A1) is oriented angularly to the longitudinal axis (X1) by an angle β between 0° and 35°.

9. Projectile part (1) according to one of claims 1 to 8, wherein the small plate has a substantially constant thickness.

10. Projectile part (1) according to one of claims 1 to 9, wherein the reference length Lzz is less than 40 mm.

11. Projectile part (1) according to one of claims 1 to 10, wherein the first dimensional ratio RD1 is between 45% and 75%12. Projectile part (1) according to claim 2, wherein the minimum width (E4) of the escapement strip is such that the second dimensional ratio RD2 is between 10% and 40%.

13. Projectile part (1) according to one of claims 1 to 12, characterized in that it is formed from rigid paper or cardboard type material.

14. Method for throwing a projectile part as defined in claim 1, the method comprising: - / a / placing the proximal support zone (ZAP) bearing on at least one first phalanx of the digital support of a hand (M) of a user, - / b / placing the distal support zone (ZAD) bearing on at least one other phalanx of the digital support, - / c / placing the thumb (F0) in the through orifice (2) with the thumbnail bearing on the intermediate bearing zone (ZAI), - / d / exerting an effort at least forwards with the thumb while maintaining the digital support against the proximal and distal bearing zones (ZAP, ZAD), - / e / allowing a slip to occur at the level of the distal bearing zone (ZAD) to cause the release of said distal bearing zone (W2) and the projection forward of the projectile part (W2, W3, W4), with simultaneous rotation induced by the delayed release of the proximal bearing zone (ZAP).

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