Bracelet clasp comprising a device for adjusting the length of the bracelet

Abstract

The invention concerns a band clasp comprising a length adjustment device, characterised in that said adjustment device is not provided with a locking mechanism for preventing length adjustment and / or an activation member intended to release a locking mechanism in order to allow length adjustment in at least one direction of the length of the band. The clasp of the present invention allows a user to make fine adjustments to the useful length of the band by pushing or pulling on the band strand.

Description

Domaine technique

[0001] The present invention relates to a clasp for a bracelet, in particular a clasp for adjusting the length of the bracelet. The invention also relates to a folding clasp and a wristwatch comprising such a clasp. Etat de la technique et problèmes à l'origine de l'invention

[0002] Wristwatch straps generally include means for adjusting the strap length. For example, in the case of leather or plastic straps, the free end of one of the two strands of the strap has a series of holes distributed in the longitudinal direction of the strap. The free end of the other strand of the strap has a connecting device, for example a pin buckle, allowing the two strands to be joined by inserting the pin into the hole corresponding to the desired length. In the case of metal link bracelets, the strap length is adjusted by removing or adding a link in one or both strands of the strap. However, in either case, the possible adjustments of the useful length of the strap are quite coarse and it is possible that the circumference of the wrist of the watch wearer lies between two adjacent settings.

[0003] The state of the art knows clasps for wristwatches that allow fine adjustment of the strap length. Such fine adjustment is desirable to precisely adapt the strap length to the wrist of the wearer of a wristwatch. On the other hand, as raised in document EP 2361523, the size of a wearer's wrist can vary with changes in temperature for example.

[0004] Many clasps equipped with a mechanism for finely adjusting the length are known from the state of the art. These mechanisms include a blocking or locking device or member to prevent involuntary or accidental lengthening and / or shortening. In several clasps, it is sought to prevent involuntary lengthening in particular, since the risk of involuntary shortening is lower. On the other hand, the possibility of being able to shorten the bracelet quickly, without the need to activate an unlocking mechanism, is even desirable for the wearer, since this possibility allows the bracelet to be tightened around the wrist simply and at any time. For example, a user whose hand wearing the wristwatch is occupied can always tighten the bracelet around his wrist by exerting pressure with the other hand on a strand of the bracelet in the direction intended to reduce the length of the bracelet.European patent EP2875747B1 shows a clasp for finely reducing the length of the bracelet by exerting a force on the bracelet strand secured to a movable part. This clasp, however, includes a locking member provided with a tooth to ensure that a movable part is held in a predefined position. To lengthen the bracelet, the user is obliged to open the clasp and press a support surface in order to release the tooth and move the movable part in the direction of the bracelet lengthening. The construction of the clasp shown in document EP2875747B1 is relatively simple, compared to other clasps provided with a mechanism for finely adjusting the bracelet length. Nevertheless, it may be desirable to further reduce the complexity of the mechanism and to further reduce the number of parts.

[0005] An objective of the present invention is to simplify or even eliminate the need for a locking device and the activation or manipulation member that must be activated by a wearer in order to lengthen the bracelet. Another objective of the invention is to facilitate length adjustment in both directions, not just in the direction of shortening the bracelet, while minimizing the risk of accidental and involuntary length change.

[0006] US 2,588,655 discloses a bracelet clasp that allows the bracelet length to be adjusted without having to activate a locking device. This mechanism has several disadvantages. On the one hand, it does not allow a discrete and stable value of the bracelet length to be adjusted, since there is always some play and residual extensibility. On the other hand, to open the clasp, it is necessary to first extend the adjustable length to the maximum. It would be advantageous to implement a clasp in which the fine adjustment and the opening of the clasp can be activated independently of each other.

[0007] CH 699 067 discloses a clasp comprising pawls and two pairs of holes, allowing a user to adjust the length of the bracelet without having to activate an activation mechanism. It would be desirable to implement a mechanism allowing the force required to adjust the length to be adjusted, for example so that the force required to shorten the bracelet is less than the force required to lengthen the usable length of the bracelet. Résumé de l'Invention

[0008] The present invention relates to a clasp for bracelets according to claim 1. This clasp comprises a device for adjusting the useful length of the bracelet making it possible to extend said useful length without needing to activate an unlocking mechanism, by acting directly on a strand connected to the clasp.

[0009] In one embodiment, said adjustment device is devoid of a locking mechanism for blocking the adjustment of the length of the bracelet in at least one direction and / or of an activation member such as a push button, a pull tab and / or a slider, said activation member being intended to unlock a locking mechanism in order to allow the adjustment of the length of the bracelet in at least one direction.

[0010] In the clasp of the invention, the useful length adjustment device comprises a movable part and a support device, the movable part being arranged to be able to move relative to said support device during a length adjustment, the movable part comprising a stop structure and the support device comprising an indexing member, or vice versa, said stop structure being intended to be positioned in a notch of the indexing member, in order to determine a discrete and stable value of the length of the bracelet.

[0011] In one embodiment, the stop structure dst is intended to be positioned in a notch of the indexing member secured to said support device or said movable part, in order to determine said discrete and stable value of the length of the bracelet.

[0012] According to the invention, said movable part, said stop structure and said notch are arranged so that, when a determined force is exerted by a user, said force acting in a longitudinal direction on said movable part or on a bracelet strand connected to said movable part, said force acts on said stop structure so as to disengage said stop structure from said notch and to cause a movement of the movable part in the longitudinal direction with the result of extending said useful length of the bracelet.

[0013] According to yet another aspect, the invention relates to a wristwatch comprising the clasp of the invention.

[0014] In one embodiment, said movable part is arranged relative to the indexing member so that the movement of the movable part when applying a thrust exerted by a user acting directly on said movable part or on a bracelet strand connected to said movable part causes the useful length of the bracelet to be shortened.

[0015] In one embodiment, said movable part is arranged relative to the indexing member so that the movement of the movable part when traction is applied by a user acting directly on said movable part or on a bracelet strand connected to said movable part causes the useful length of the bracelet to be extended.

[0016] In one embodiment, the thrust and / or traction force required to enable the movement of the movable part is determined at least in part by the profiles and / or shapes of the stop structure and the notches intended to receive said stop structure in order to determine a discrete length value.

[0017] In one embodiment, said indexing member comprises a plurality of notches, said notches comprising at least one contact structure, preferably a contact surface, and said stop structure comprising a bearing surface arranged to be in contact with said contact structure and to slide on said contact structure during a movement of the movable part causing the lengthening and / or shortening of the useful length of the bracelet.

[0018] In one embodiment, said stop structure is a tooth comprising a first and a second bearing surface, and said bearing surfaces, seen in profile, each follow a straight line, each of the straight lines forming an angle relative to a radial axis, each of the angles being non-zero, preferably greater than 10°.

[0019] In one embodiment, said movable part comprises a carriage and said stop structure is arranged relative to the carriage so as to be able to move in a direction comprising a radial component, the radial component of the movement allowing said stop structure to slide on a support structure of a notch and to disengage from said notch in which said structure is positioned.

[0020] In one embodiment, said indexing member and said stopping structure of the movable part are arranged so that the force in the longitudinal direction, preferably a push, required to achieve the movement of the movable part to shorten the bracelet length, is less than the force, preferably a pull, required to achieve the movement of the movable part to lengthen the bracelet.

[0021] In one embodiment, said length adjustment is a discontinuous fine length adjustment, in discrete length values.

[0022] In one embodiment, the clasp is arranged to allow length adjustment when the clasp is in the open position as well as when the clasp is in the closed position.

[0023] Other aspects of the invention and preferred embodiments are defined in the claims and description below. Brève description des dessins

[0024] The characteristics and advantages of the invention will appear more clearly on reading a description of a preferred embodiment, in no way limiting, given solely by way of example, and made with reference to the schematic figures in which: There figure 1 is an exploded perspective view of a clasp according to a first embodiment of the present invention; figure 2 is a perspective view showing the underside of the clasp cover of the figure 1 . There figure 3 is a longitudinal sectional view of the clasp of the figure 1 in a first configuration. The figures 4A , 4B , 4C And 4D represent simplified extracts of a longitudinal section of the clasp of the figure 1 in different configurations. The figure 5 represents a simplified extract of a longitudinal section of the clasp of the figure 1 in a particular configuration. The figure 6 is a cross-sectional view showing the cover and the movable part of the clasp of the figure 1 . There figure 7 is an exploded front view of the moving part of the clasp of the figure 1 . There figure 8A is a perspective view of a clasp according to a second embodiment of the present invention. figure 8B is a side elevational view of a blade of the clasp shown in figure 8A . THE figures 9A et 10A are longitudinal sectional views along the AA axis of the figure 8B , showing the length adjustment mechanism in the rest and activated positions, respectively. The figure 9B et 10B are enlargements of extract B of the figures 9A et 10A , respectively. The figure 11 is a perspective view of a clasp according to a third embodiment of the present invention. figure 12 is a side elevational view of a blade of the clasp shown in figure 11 . There figure 13 is a longitudinal sectional view along AA of the figure 12 . THE figures 14A et 14B are enlargements of extract B of the figure 13 , in which the length adjustment mechanism is respectively in the rest position or activated. Description des modes de réalisations

[0025] The clasp illustrated in the figures, without limitation, corresponds to a preferred embodiment of the present invention. In particular, the clasp 1 is of the folding clasp type and is intended in particular to close a watch strap. The strap can be of any type, such as for example made of flexible plastic, leather, or made by an assembly of metal links.

[0026] In general, clasps comprising a device for fine adjustment of the useful length of the bracelet comprise at least two parts arranged so as to be able to perform a relative movement in the longitudinal direction with respect to each other. Each of the two parts comprises a fixing member. A first fixing member is intended to be connected to a first bracelet strand, and the second fixing member is intended to be connected to a second bracelet strand. In this configuration, the relative movement mentioned above causes the fixing members to move closer together or further apart and thus the shortening or lengthening of the useful length of the bracelet.

[0027] Often, one of the two parts arranged to be able to carry out the relative movement is designated as the "moving part". In this specification, the same designation is used, and the other of the two parts is designated as the "support device". Since this is a relative movement between two parts and / or two assemblies, the part that is considered the "moving part" is only a matter of convention. This designation is arbitrary since it is a relative movement. Generally, it is the smaller of the two parts that is designated the moving part, the other part often comprising the mechanism for closing and opening the clasp, for example in the form of articulated blades.In the context of the present invention, the "moving part" could be called the "first moving part" and the "supporting device" could be called the "second moving part", the first and second moving parts being capable of relative movement in the longitudinal direction.

[0028] Typically, the movable part and the support device cooperate by means of, on the one hand, an indexing member, such as a series of notches, a rack, and / or a toothing, for example, and on the other hand, a stopping structure, a jaw or even a lock, intended to cooperate with the indexing member in order to determine discrete values ​​of useful length. The difference in length between the values ​​is determined by the spacing between the notches of the indexing member. A discrete and stable value corresponds to a concrete position, defined by the positions of the notches, in which the movable part is stabilized and / or stopped relative to the support device thanks to the interaction of the stopping structure and the rack in the absence of an external force.

[0029] In the case of the embodiment shown in the figures 1-7 , the indexing member 6 is associated with the support device 20-23 and the stop structure 10 is associated with the movable part. The clasp can also be made vice versa, that is to say by associating the indexing member 6 with the movable part and the stop structure 10 with the support device 20-23, without departing from the scope of the present invention.

[0030] THE figures 8A à 14B show embodiments in which the two structures, the indexing member and the stop structure, are arranged inversely, i.e. the indexing member is associated and thus integral with the movable part. Generally speaking, the indexing member is preferably integral with the structure with which it is associated, or with the support device ( figs 1-7 ) or of the moving part ( figs 8A-14B ), as the case may be. The stop structure is arranged respectively on the other of the two structures, in order to be able to generate cooperation between the two structures.

[0031] Clasp 1 shown in the figures 1-7 includes a conventional "clasp" function, i.e. without a device for finely adjusting the useful length of the bracelet, which is described in detail in patents EP 0913106B1 and EP2875747B1, issued in the name of the Applicant.

[0032] These conventional functions of the clasp 1 will be described briefly below. The clasp 1 is intended to be connected to two strands of a bracelet (not shown) in a known manner, in particular to the free ends of the strands. As described in the aforementioned patents EP0913106B1 and EP2875747B1, the clasp 1 comprises a base 20, of elongated shape along the longitudinal direction of the bracelet and slightly curved over at least part of its length to better fit the shape of a wearer's wrist.

[0033] The terms "strap length direction" or "strap longitudinal direction" are used in this specification to refer to an axis that is that of the two strap strands, assuming that the strap is laid flat and detached from a watch. When the strap is closed, the "strap length direction" refers to the line that follows the circumference of the strap. The strap length adjusted by fine adjustment using the clasp adjustment device according to the invention is in the strap length direction. In the case of a wristwatch with a conventional dial, an axis connecting the numbers 6 and 12 on the dial generally follows the strap length direction in accordance with this definition.

[0034] The clasp shown in the figures 1-7 is substantially symmetrical and therefore has a plane of symmetry that extends in the direction of the length of the bracelet. The terms "orthogonal" and "transverse" refer to an axis that is perpendicular to the "direction of the length of the bracelet" and perpendicular to the plane of symmetry of the clasp. In the case of a wristwatch with a dial, an axis connecting the numerals 3 and 9 on the dial has an "orthogonal" direction in accordance with this definition.

[0035] A "radial" axis is an axis that is radial to the axis of a wristwatch wearer's wrist or forearm. The radial axis extends in the plane of symmetry or in a plane parallel to the plane of symmetry. In the view of figures 3 , 4A-4D , 5 , 6, et 7 , the "radial" axis is a substantially "vertical" axis, and the two terms are generally used interchangeably in this specification.

[0036] In the context of the profile of the stop structures and notches of the indexing member, the "vertical" is a straight line and preferably a plane which is normal to the direction of movement of the moving part.

[0037] The terms "bottom" and "top" generally refer to the bottom and top of the clasp respectively as shown in the figure 3 The expressions "below" and "above" are to be understood analogously, the structural elements close to the wrist being "below" the more distant elements.

[0038] While the terms "longitudinal direction of the bracelet", "orthogonal" and "radial" refer to the orientation of an element of the clasp or an axis of that element, these terms generally refer to the orientation of the element or its axis when the clasp is closed.

[0039] The base 20 comprises two longitudinal members 21 spaced from each other and secured to a transverse spacer 24 arranged at a first end of the longitudinal members 21. A fixing member 12 intended to be connected to a free end of the bracelet, by means of a bar or rod (not visible), is secured to the transverse spacer 24. In the present description, the member 12 corresponds to a second fixing member intended to be connected to a second bracelet strand (not illustrated), the first fixing member 11 being connected to the mobile part as described below.

[0040] A folding arm 22 formed by two branches 22.1 and 22.2 is pivotally mounted at the opposite end of the side members 21, in a conventional manner. The opposite ends of the branches 22 serve both to connect the cover 23 to the branches 22.1, 22.2 and to house the pushers 28 which enable the locking mechanism of the clasp to be activated, enabling the clasp to be opened by unfolding the arm 25 of the base 20. The pushers 28 are arranged so as to act on the branches 22.1, 22.2 to bring them closer to each other when they are actuated by a user wishing to open the clasp 1. The relative bringing together of the two branches 22.1, 22.2 has the effect of releasing claws 36 provided on the branches and inserted into complementary recesses 38, provided in the base 20, as has been described in detail in patents EP0913106 B1 and EP2875747B1.

[0041] In this specification, a "user" is preferably a wearer of the clasp, preferably an individual wearing on their wrist a wristwatch comprising the clasp.

[0042] In the embodiment shown in the figures, the device for adjusting the useful length of the bracelet is associated with the cover 23.

[0043] The adjustment device comprises a movable part 2 comprising a carriage 3 mounted to slide inside the cover 23. For this purpose, the carriage 3 comprises a pair of lateral guide pads 72, intended to be inserted into two guide grooves 4, respectively arranged on either side on the inner faces of the two side walls 68 of the cover 23. In the embodiment shown, the guide grooves 4 have a curvature identical to that of the cover 23. They each open out at one of the ends of the corresponding side wall.

[0044] Each guide shoe 72 is intended to cooperate with a guide groove 4. Thanks to these characteristics, the carriage 3 can be engaged under the cover 23, by engaging the guide shoes 72 to be able to slide therein. The guide shoes 72 preferably have an elongated shape along the longitudinal direction of the bracelet, such that the carriage 3 can only move by sliding along the guide grooves 4.

[0045] The carriage 3 houses a transverse part 5 having, in the embodiment shown, an elongated shape and the general appearance of a bar. The part 5 comprises a stop structure 10. In the embodiment shown, the stop structure comprises two teeth 10. The two teeth 10 are arranged on the same transverse axis and are separated by a gap in which a stop finger 64 is arranged. Hereinafter, the singular and plural forms of the term "tooth" refer to the same stop structure comprising the two teeth 10. The present invention is not limited by the number of teeth used to form the stop structure and covers, for example, the use of one or more stop structures, for example two partial stop structures, together forming a stop structure.

[0046] The mounting of part 5 on carriage 3 is such that it leaves part 5 only one degree of freedom to move when part 5 is mounted on carriage 3, and when carriage 3 is mounted under cover 23. Part 5 has two holes 31, arranged close to its lateral ends. As can be better seen in figure 6 , a screw 7 is inserted into each of these holes in order to connect the part 5 to the carriage 3. Return means 8, here springs, are arranged on the barrel of the screws between the bottom 74 of the carriage 3 and the lower face of the part 5 so as to urge the part 5 in a radial upward direction, while allowing the part to lower when a force in the opposite direction, downwards, acts on the part 5. In other words, in the embodiment shown, the part 5 comprising the tooth 10 is housed so as to be able to perform a translational movement, preferably a rectilinear translational movement. Preferably, this translational movement takes place along a radial axis. In the embodiment shown, this movement is guided by the two screws 7.

[0047] On the other hand, the part 5 is housed between a front wall 44 and a rear wall 48 which help to guide the translation of the part 5 in the radial direction relative to the carriage 3. These walls are connected to the bottom 74 of the carriage 3. Once mounted in the cover, the part 5 is further blocked laterally by the side walls 68 of the cover 23 ( figure 6 ).

[0048] On the figure 2 the lower face of the cover 23 is visible. A longitudinal central groove 69 is provided inside the upper wall 26 of the cover 23. On either side of the central groove, two indexing members 6 are provided in the lower face of the wall 26. In the embodiment shown, these indexing members 6 are produced in the form of two parallel racks or teeth 6. In general, the indexing member can be produced, for example, in the form of a series of notches 14 or two series of parallel notches, for example. In the present description, the reference number 14 is used both to refer to any notch in general and to designate a particular notch.

[0049] When the movable part 2 is mounted in the cover, each of the teeth 10 cooperates with one of the teeth 6, as shown in figures 3 And 6and described in more detail below. It should also be noted that the maximum travel finger 64 is arranged in the middle on the part 5. This finger 64 is intended to slide in the central groove 69, so that the ends of the groove serve as a travel stop for the carriage 2.

[0050] The carriage 3 comprises a pair of side walls or ears 73, each comprising a transverse hole 11. These holes act as a first fixing member 11, since they allow a spring bar to be housed in a manner known per se. The free end of a first bracelet strand can be connected by this bar to the carriage 3 of the movable part 2.

[0051] When assembling the movable part 2 in the cover 23, the part 5 is first connected by screwing between the front and rear walls 44, 48 of the carriage 3, as shown in figure 6 . Each of the screws 7 passes through one of the holes 31 in the part 5 and the interior space of one of the springs 8, and is anchored in the frame or bottom 74 of the carriage 3. The springs 8 are fitted onto the barrels of the screws between the part 5 and the frame of the carriage, so as to form a void space 32 between the frame of the carriage and the part 5. By virtue of this arrangement, the part 5 can move in a radial direction, guided by the screws 7 and along a distance defined by the height of the head of the screws 7. The head of the screws 7 fits into a recess 33 arranged in each of the holes 31 to retain the part 5. The movement of the part 5 is countered by the force of the springs downwards or biased by the force of the springs upwards in the figures 3 And 6 .

[0052] The assembly 2 is then attached to the cover 23 by inserting the side pads 72 through the open ends of the side grooves 4. When the movable part 2 is pushed into the side grooves, the part 5 is forced to lower into its housing between the walls 44 and 48, because the edge 67 of the free end of the cover 23 acts by reaction force on the teeth 10 of the part 5, and this force is transmitted to the springs. The lowering of the part 5 into its carriage 3 against the force of the springs 8 thus allows the insertion of the movable part during assembly. When the movable part 2 is further inserted into the cover, the teeth 10 of the part 5 are continuously urged towards the lower face of the cover (upwards), until the teeth 10 come into cooperation with the racks 6.At this point, the teeth 10 engage with the first notch of the racks 6 and the travel finger 64 engages with the central groove 69. In this configuration, shown in . figure 3 , the movable part 2 is stably associated with the cover 23, it can then only carry out the movement provided for the adjustment of the useful length as will be described further below.

[0053] A particular feature of the clasp of the invention is that, in a preferred embodiment, it lacks an actuating or manipulating member intended to unlock the fine adjustment stop structure from its engagement with the indexing member. Such unlocking is necessary in the clasps of the prior art in order to be able to move the movable part in at least one of the two directions of the useful length adjustment. Generally, at least the adjustment allowing the extension of the useful length of the bracelet is prevented by a locking or blocking mechanism then requiring unlocking by means of an actuating member. Preferably, the clasp of the invention is devoid of such a manipulating member for unlocking the fine adjustment. The clasp is preferably also devoid of a locking mechanism completely blocking the movement of the movable part in at least one longitudinal direction.

[0054] The invention lies in the implementation of an indexing mechanism making it possible to stabilize the mobile part 2 relative to the other parts of the clasp, called here "support device" 20-23, while allowing adjustment of the useful length by the application of a force by the user in a precise direction, generally in the desired direction, of shortening or lengthening the length.

[0055] In the embodiment shown, this mechanism is based on the configuration and / or geometric shape of the stop structure 10 of the movable part 2 and of the indexing member 6 cooperating with the stop structure 10, and more precisely of the complementary and cooperating geometric shapes of the stop structure 10 and of the indexing member 6. Preferably, these shapes are chosen so as to allow a movement of the movable part even in the absence of an unlocking. Preferably, the geometric shapes determine, together with the force of the return means 8, the force required to carry out a movement allowing the adjustment of the useful length.

[0056] In the embodiment shown in the drawings, the stop structure 10 comprises a tooth. Unlike the solution presented in patent EP2875747, the two flanks 18, 19 of the tooth 10 are inclined relative to a radial axis. Since neither of the flanks of the tooth 10 is vertical, there is no complete blocking, and the profile and / or the inclination of each of the flanks of the tooth is preferably chosen so as to determine the force required to effect the displacement of the movable part in the longitudinal direction.

[0057] In the figures 4 B et 4 C , the profiles of the tooth 10 of the stop structure and of the notches 14 of the indexing member are visible and the angles of the flanks of the tooth and of the notches relative to a vertical 15 are indicated. figure 4B , the first flank 18 (the "front" flank) of the tooth 10 is straight and follows an angle α of approximately 63° relative to the vertical 15, or approximately 27° relative to a horizontal axis in the figure 4A . The opposite flank 19 of the tooth 10 (the second flank, or the rear flank) forms an angle β of approximately 42° with the vertical 15.

[0058] The notches 14 of the indexing member 6 have a profile substantially complementary to that of the tooth 10, in order to allow the tooth 10 to be received and to determine a position of discrete length, stabilized by the cooperation of complementary shapes, as shown in figures 3, et 4A And 4D This discrete position is also stabilized by the action of the spring 8, which pushes the tooth in a vertical direction, towards a notch 14, in order to bring the tooth into engagement with the notch.

[0059] In the embodiment shown, the indexing member 6 is produced in the form of a toothing or a rack. The geometry of the notches 14 is essentially defined by the interdental space, that is to say by the tooth hollow of the toothing 6.

[0060] To the figure 4C , the first and second flanks or bearing surfaces 16, 17 are shown. The profile of the first bearing surface 16 follows a straight line which makes an angle y with the vertical 15. The profile of the second bearing surface 17 follows a straight line which makes an angle δ with the vertical 15.

[0061] Considering the three dimensions, the flanks 16, 17 (as well as the flanks 19, 18) are planar and these planes are preferably inclined relative to the direction of movement of the movable part. If the vertical 15 is considered as a plane which extends in an orthogonal direction, the planes 16, 17, 18, 19 intersect the vertical plane at an angle (α, β, y, δ), so that the intersection substantially follows the orthogonal direction.

[0062] Due to the complementarity between each of the notches 14 and the tooth 10, the first profiles 18, 16, respectively of the tooth 10 and the notch 14, intended to be in contact in an indexing position, are preferably substantially parallel. Consequently, the angles α and γ formed between these profiles and the vertical are preferably substantially identical, for example identical within a margin of error of 0 to 10 degrees, preferably 0 to 5 degrees.

[0063] Likewise, the second profiles 19, 17, respectively of the tooth and the notch 14, intended to be in contact in an indexing position, are preferably substantially parallel. Consequently, the angles β and δ formed between these profiles and the vertical are preferably substantially identical, for example identical in a range of 0 to 10 degrees, preferably 0 to 5 degrees.

[0064] In the embodiment shown, the angles α and β are not identical. Therefore, the tooth 10 has an asymmetrical profile. Preferably, the value of the angles α and β differs by at least 4°, preferably by at least 8°, more preferably by at least 14°. For example, α is at least 4° larger than β. The profile of the notches 14 is also asymmetrical, due to their complementary configurations, allowing the notch to receive the tooth substantially "tailor-made". At this point it should be mentioned that the tooth of the structure in patent EP2875747B1 is also asymmetrical, but one flank of the tooth profile is substantially vertical, which is why unlocking of the tooth by means of a separate mechanism is necessary. In the case of the aforementioned patent, the stop structure is pivotable as a whole, and a user can operate a sort of pusher in order to disengage the tooth from the notch.

[0065] THE figures 3 , 4A-4D illustrate the reduction of the useful length of the bracelet. Thus the movable part 2 is moved from left to right relative to the other parts of the clasp, in particular relative to the cover 23 and relative to the set of folding blades 22, 23, when the clasp is closed. The clasp can remain closed during this shortening, as illustrated in the figures. As mentioned, the end of a first bracelet strand is attached to a fixing member 11 of the carriage 3. A user can carry out the shortening by grasping the bracelet strand between the thumb and index finger and exerting a push in the direction of the arrow 30 ( fig. 4B ), i.e. directly in the direction of the desired shortening. The force of the thrust in the longitudinal direction 30 will be transmitted to the tooth 10. More precisely, the force acts from the first flank 18 of the tooth 10 on the first bearing surface 16 of a notch 14, with which the flank 18 is in contact. Since the bearing surface 16 cannot move, it retransmits a reaction force onto the tooth 10. The latter being urged into its vertical position by the spring 8, the reaction force is transmitted by the part 5 to the spring. If the force is sufficiently high, the spring 8 is compressed and the tooth 10 is forced to lower into its housing while the carriage 3 performs a movement in the longitudinal direction 30, as shown in figures 4B et 4C . During this movement, the tooth leaves its notch and then comes into engagement with the next notch, as shown in the figure 4D During this movement, sliding takes place between the surfaces of the flank 18 of the tooth and the support surface 16.

[0066] The force required to effect the movement described above depends on several factors, including the force of the spring 8 and the friction between the first flank 18 of the tooth and the corresponding first bearing surface 16 of the notch. On the other hand, the force also depends on the inclination of the flank 18 and the corresponding bearing surface 16, since due to this inclination, the force in the longitudinal direction (substantially horizontal in the figures 3 , 4A-4D ) is broken down into partial forces including a vertical partial force which allows the spring 8 to be compressed and the tooth 10 to be released from its housing in the notch. If the first flank 18 was horizontal on the figure 4B , there would be no tooth and the force in the direction of arrow 30 would be directly translated into longitudinal displacement. If the flank 18 were vertical and abutted against an equally vertical bearing surface 16, a transmission of the force into a partial vertical force would be prevented and the movement of the carriage 3 completely blocked. Thus, the geometry of the cooperating shapes of the tooth 10 and the notch 14 is chosen to determine the thrust force required to effect the sliding between the surfaces 16, 18 and thus the movement of the movable part 2 relative to the "fixed" part of the clasp 1. Preferably, this force is small enough that a user can easily effect the shortening of the clasp 1 by proceeding as described above. At the same time, this force is high enough that the risk of accidental and unwanted shortening is reduced.

[0067] In the embodiment shown, the profile of the second flank 19 of the tooth 10 does not follow a vertical axis, but the aforementioned angle β, this angle being preferably more than (greater than) 0°, preferably more than 3°, more preferably more than 5° and more preferably more than 7°, for example more than 10°, more than 15° or even more than 20°. Since this second flank 19 of the tooth 10 is also inclined (as is the case with the first flank 18 and the angle α), the cooperation between this flank 19 and the complementary surface 17 of the notch also does not cause complete blocking in the direction according to the arrow 40 ( Fig. 5 ), more precisely in the direction of lengthening the bracelet.

[0068] The above indications concerning the configuration of the first flank 16 and the first bearing surface 18 and the shortening also apply to the second flank 19 and the second bearing surface 17 in the context of an increase in the useful length. The operation of the mechanism during an extension of the useful length is illustrated in the sequence of Figures 4D, 5 And 4A .

[0069] In this case, a user wearing a wristwatch having the clasp grasps the first bracelet strand exactly as described above, between the thumb and index finger. Instead of pushing, the user pulls to extend the useful length. In this case, it is the second flank 19 of the tooth 10 which is pulled towards the second bearing surface 17, which generates a vertical partial force making it possible to push the part 5 further into its housing in the carriage 3 and thus to release the tooth 10 from its housing in the notch 14, by sliding between the cooperating surfaces 17, 19, of the notch 14 and the tooth 10 respectively, as shown in figure 5 .

[0070] The geometric shapes or configurations of the contact surfaces between the second flank 19 and the second complementary and / or cooperating bearing surface 17 are produced in such a way that the tensile force required to effect the movement in the direction of the arrow 40 used to lengthen the bracelet ( Figure 5 ) is higher than the force of the thrust required in the opposite direction, according to arrow 30 ( Figure 4B ) to shorten the useful length. The risk of accidental lengthening is then lower than that of accidental shortening.

[0071] In the embodiment shown, the adjustment of the force is achieved by the shape and / or profile of the cooperating surfaces 16, 18 and 17, 19, respectively, for shortening and lengthening. More specifically, the force is determined by the choice of the angles β and δ of the profile of the second flank 19 and the second bearing surface 17 relative to the vertical, respectively. As can be seen in figures 4B et 4C , the angles β and δ are not only greater than 0, but smaller than the angles α and γ of the opposite corresponding faces. In other words, the profiles of the flank and the surface 19, 17 are closer to the vertical, which is why the force required to effect the movement in the direction of the arrow 40 is higher. In fact, the traction force required to cause the movement of the tooth 10 decreases as the angle of the flanks / bearing surfaces increases and approaches the horizontal (90°). By choosing the profile of the teeth and the corresponding notch, it is possible to adjust the force required to cause the adjustment of the useful length. For example, according to one embodiment, the force required to effect the lengthening is greater than that required to effect the shortening.

[0072] Accidental shortening is considered less troublesome, which is why the risk of accidental lengthening is reduced by the shape and orientation of the contact surfaces between the tooth and the notch. It should be noted that, according to the invention, an accidental change in length is not completely excluded, but the probability of such a change is reduced by creating a mechanism requiring a pulling force or a pushing force in a desired direction so that an involuntary and accidental change in length becomes unlikely.

[0073] The clasp of the present invention allows adjustment of the useful length of the bracelet by the following preferred features: (1) the absence of a locking mechanism completely blocking the movement of the movable part in at least one direction, preferably in both directions. Therefore, a mechanism intended to be actuated by a user to unlock the locking mechanism and thus to allow the length adjustment is also absent. (2) The fine length adjustment device comprises an indexing member defining discrete length positions. The force required to move the movable part is determined by the shape and orientation of the parts which are intended to slide over each other during the length adjustment.In the embodiment shown in the drawings, the movable part is provided with a tooth and the support part comprises a rack whose notches have a profile substantially complementary to that of the tooth.

[0074] THE figures 8 à 10B show a clasp 100 according to a second embodiment, in which an indexing member in the form of a rack 106 is arranged on a first part or movable part 102, and a stop structure 110 is arranged on a second part or support part 120.

[0075] There figure 8 shows the entire clasp 100, comprising a first blade 120 comprising two lateral longitudinal members 121 spaced from each other and being integral with a transverse spacer 124 arranged at a first end of the longitudinal members 21 and / or of the first blade 122. The clasp 100 also comprises a second blade 122 arranged to be able to be inserted into the space arranged between the two lateral longitudinal members 121 of the first blade 120. A first end of the second blade 122 is pivotally mounted at a second end of the first blade 120. As already described above with respect to the clasp 1 according to a first embodiment, the second blade 122 comprises two branches 122.1, 122.2, arranged to be able to move towards each other, when a user activates the pushers 128, one of which is arranged on each of the branches 122.1, 122.2, at the second end of the second blade.Bringing the branches together allows you to unlock and thus open the clasp, as already described.

[0076] A second fastening member 112 having the appearance of a pin buckle is arranged at the second end of the second blade 122. A nail (not visible) is arranged on the lower face of the transverse plate of the pin buckle 112, making it possible to fix a bracelet strand by passing this nail through a hole in the strand. It is also possible to provide a pin (not visible) for this purpose.

[0077] Unlike the clasp 1 of the first embodiment, the movable part 102 of the clasp 100 is arranged at the first end of the first blade 121, as shown in the figures 9A à 10B . THE figures 9 A And 10 A show longitudinal sections through the first blade 120 along the line AA indicated in figure 8B .

[0078] As visible to the figures 9 A et 10 A , the movable part 102 has a U shape, the two free branches or wings 171, 172 being housed in passages and / or channels 104 arranged in the transverse spacer 124. On the branch 172, an indexing member 106 is arranged. In the embodiment shown, this indexing member is a toothed rack 106 arranged on a first branch 171 of the movable part 102. The teeth of the rack 106 are oriented in a central orthogonal direction, towards the inside of the clasp.

[0079] A stop structure 110 is housed in the transverse spacer 124. The spacer 124 has an elongated cavity or housing 132 in the orthogonal direction, which opens towards the channel 104. The stop structure 110 has the shape of a bar, one end of which forms a tooth arranged to pass through the opening of the housing 132 and to be inserted into a notch 114 of the rack 106. A return means 108, preferably a spring, is arranged in the blind end of the housing 132, in order to urge the stop structure towards the rack to stabilize the cooperation between the tooth 110 and a notch 114 of the rack.

[0080] The notches 114 of the indexing member 106 have shapes and / or profiles substantially complementary to that of the tooth 110, in order to allow the tooth 110 to be received and to determine a position of discrete length, stabilized by the cooperation of complementary shapes, as described above with respect to the figures 3, et 4A And4D .

[0081] THE figures 10A et 10B illustrate the stop structure 110 released from its notch 114, in order to be able to indicate the profiles and / or complementary shapes of the cooperation between the tooth and the notch.

[0082] As in the case of the first embodiment, the tooth 110 and each of the notches 114 comprise a first profile or flank, 118 and 116 respectively. The first two profiles 118, 116 are intended to be in contact in an indexing position.

[0083] Preferably, the first profiles or flanks 118 and 116 are substantially parallel. Consequently, the angles α and γ formed between these profiles and the vertical 15 are preferably substantially identical.

[0084] Likewise, the second profiles or flanks 119, 117, respectively of the tooth and of the notch 114, intended to be in contact in an indexing position, are preferably substantially parallel. Consequently, the angles β and δ formed between these profiles and the vertical 15 are preferably substantially identical.

[0085] The indications given above with respect to the geometry and / or profiles of the notch and / or tooth of the first embodiment apply by analogy to the second embodiment. As in the case of the first embodiment, a user can lengthen or shorten the useful length of the bracelet by exerting traction or a push, respectively, on the bracelet strand attached to the first fastening member, or directly on this fastening member if possible, for example if the latter can be grasped by the user.

[0086] The comparison of the first and second embodiments illustrates, among other things, that the manner in which and / or the location where the movable part is arranged on the entire clasp can be determined by a person skilled in the art according to design choices or other preferences or constraints and is not a limiting characteristic of the invention. Similarly, the invention is not limited with respect to the arrangement of the indexing member, on the movable part or on the support part.

[0087] THE figures 11 à 14B show a clasp 200 according to a third embodiment, in which the device for adjusting the useful length of the bracelet comprises a locking device provided with an activation member, arranged so that the length adjustment device can be activated (and thus the useful length adjusted) without or with the activation of said locking device.

[0088] The 200 clasp shown at figures 11 à 14B is similar to that shown in WO2018234474, but adapted to the present invention. The general mechanism of this clasp, in particular the opening mechanism, is not described again below.

[0089] The clasp 200 comprises first and second folding blades 220, 222. The activation members 228 for opening the clasp are arranged on the second blade, and the device for adjusting the useful length of the bracelet is arranged on the first blade 220. It should be noted that the second blade 222 comprises two branches 221 and 224 arranged to be able to approach in an orthogonal direction when the activation members 228 are pressed, in order to allow the unlocking and opening of the clasp, in a similar manner to what has been described above with respect to the first and second embodiments.

[0090] The first blade 220 comprises a support structure or device 223, integral with the first blade and arranged centrally, in the orthogonal direction, on the latter. This support structure can be formed in one piece with the first blade or in the form of a separate piece made integral with the first blade, for example.

[0091] The support structure 223 comprises a free end 267, preferably in proximity to a first end of the first blade 220. A movable part 202 is arranged in a longitudinal housing 204 in the support structure 223 so as to emerge from said free end 267.

[0092] On the lower face of said moving part 202, a first fixing member 211 is arranged, a second fixing member being arranged on said second blade 222. figure 12 , the first fixing organ (two nails arranged below the moving part), has been omitted).

[0093] The support structure 223 also comprises a housing 232 for a stop structure 210 as well as for an activation member 251 connected to said stop structure.

[0094] The movable part 202 is housed so as to be able to slide along a longitudinal direction, and comprises a rack 206 on one of its sides. The part comprising the stop structure 210 as well as the activation member 251 is housed so as to be able to move in an orthogonal direction. A rod 252 connects the activation member to the stop structure 210 by passing over the movable part 202, so that the activation member 251 and the stop structure are arranged on either side of the movable part, connected by the rod.

[0095] It should also be mentioned that at least one return means, here two springs 208, are arranged so as to bias the stop structure in an orthogonal direction towards the rack 206, in order to stabilize the cooperation between the stop structure and a notch 214 of the rack.

[0096] To activate the fine adjustment device, a user can act on the activation member 251, by pushing on this member, which causes the disengagement of the stop structure 210 from its notch 214 in the rack. The user can then adjust the useful length of the bracelet as desired, before releasing the activation member 251, causing cooperation between the stop structure and a (other) notch 214 of the rack and thus stabilizing a discrete length value.

[0097] A peculiarity of the clasp of the figures 11 à 14B lies in the fact that the activation member 251 of the length adjustment device can not only be activated directly, for example by pressing with a finger on this member when the clasp is open, but also indirectly, by activating an activation member 228 of the clasp opening mechanism, as described in more detail in document WO2018234474. This is possible only when the clasp 200 is closed. In this configuration, one of the branches 221 of the second blade 222 is aligned with and / or directly next to the activation member 251. The activation of the pusher 228 connected to the branch 221 causes the lateral movement of the branch 221 and the support of this branch on the activation member 251. Thus, the movement of the branch 221 of the second blade causes the disengagement of the stop structure 210 from the rack 206 by pressing on the activation member 251.

[0098] As can be understood from the figures 14A et 14B , the stop structure 210 comprises a tooth whose shape, profile and / or flanks are complementary to the shapes, profiles and / or flanks of the notches 214 of the rack 206. On the other hand, the tooth 210 and each notch 214 comprises inclined flanks and / or profiles, so as to allow disengagement of the tooth 210 from its notch 214 when a force in the longitudinal direction, therefore a pull or a push, is exerted on the movable part 202. Such a pull or push is typically carried out by a user who grasps the bracelet strand connected to the movable part 202 by the fixing member 211 and who pulls or pushes the strand to lengthen or shorten, respectively, the useful length of the bracelet.

[0099] Thus, the useful length of the bracelet according to the third embodiment can also be adjusted without activating a locking / unlocking mechanism, in particular without activating a separate activation member, but by pulling and / or pushing directly on the bracelet strand, for example near the end of the strand which is attached to the fastening member.

[0100] As indicated above, in one embodiment, the adjustment device is devoid of a locking mechanism for blocking the length adjustment of the bracelet in at least one direction and / or of an activation member such as a pusher, a pull tab and / or a slider.

[0101] In the case of the clasp shown in figures 11 à 14B , an activation member is present. But preferably, this actuating member 251 does not block the movement of the movable part. A locking of the movable part in at least one longitudinal direction is absent, due to the complementary shapes mentioned above.

[0102] In some cases, the fixing member secured to the movable part is prominent and / or accessible to a user so that it can be grasped by the latter (e.g. the fixing member 111 shown in figure 8A ). In these cases, the user can logically adjust the length by acting directly on the fastening member instead of performing the pull / push by gripping the bracelet strand. This may be desirable when the bracelet is very flexible and when it is not easy to transmit the force to the moving part by gripping the bracelet strand due to this flexibility.

[0103] It should be mentioned that in several embodiments shown, the clasp locking mechanism, i.e. the mechanism provided to prevent accidental opening of the clasp and to enable clasp opening, is activatable independently of the fine adjustment mechanism. The fine adjustment mechanism can be activated separately and independently of the clasp locking device. Furthermore, the usable length of the bracelet can be adjusted when the clasp is open, but also when it is closed, even when the wristwatch is in service mode, on a user's wrist.

[0104] A person skilled in the art will not encounter any particular difficulty in adapting the content of the present disclosure to his own needs and implementing a clasp, in particular for a timepiece, without departing from the scope of the present invention. For example, a person skilled in the art can adapt the teaching to a pin buckle or to a combined buckle (pin / folding blades). In combined buckles, the clasp comprises folding blades, and at least one fastening member is made in the form of a pin buckle. More generally, the length adjustment device according to the invention can be adapted to other types of clasps, in particular for wristwatches. Furthermore, a person skilled in the art will understand that the positioning of the stop structure (e.g. the tooth) and the indexing member (e.g. the rack) on the moving part and the support part, respectively, result from a design choice.The invention covers the possibility of positioning the indexing member on the movable part and the stop structure on the support part of the length adjustment device.

Claims

1. Clasp (1) for wristbands, comprising a device for adjusting the useful length of the wristband (2-8), said device for adjusting the useful length comprising a movable part (2) and a support device (20-23), the movable part (2) being arranged so to be displaceable relative to said support device (20-23) during a length adjustment, one of said movable part (2) and said support device (20-23) comprising a stop structure and the other comprising an indexing member (6), said stop structure being intended to be positioned in a notch (14) of the indexing member (6), in order to determine a discrete and stable value of the length of the wristband, characterized in that said stop structure comprises a tooth (10) having an asymmetrical profile, said tooth comprising a first and a second bearing surface (18, 19) and in that, seen in profile, said bearing surfaces (18, 19) each follow a straight line, each of the straight lines forming an angle (α, ß) with respect to a plane (15) which is normal to the displacement direction of the movable part, each of the angles (α, ß) being non-zero, the angles (α, ß) not being identical, and in that said movable part (2), said tooth (10) and said notch (14) are arranged in such a way that, when a determined pulling force is exerted by a user, said force acting in a direction in the longitudinal direction on said movable part (2) or on a wristband strand connected to said movable part (2), said force is transmitted to said tooth (10) so as to disengage said tooth (10) from said notch (14) and generate a displacement of the movable part (2) in the longitudinal direction, resulting in the lengthening of said useful length of the wristband.

2. Clasp (1) according to claim 1, characterized in that said force is a pulling force that allows the useful length of the wristband to be lengthened.

3. Clasp according to either of claims 1 and 2, characterized in that said movable part (2) is arranged relative to the indexing member (6) in such a way that the displacement of the movable part (2) during the application of a push exerted by a user acting directly on said movable part (2) or on a wristband strand connected to said movable part (2) results in the shortening of the useful length of the wristband.

4. Clasp (1) according to any of claims 1 to 3, characterized in that the push and / or the pulling force required to allow the displacement of the movable part (2) are determined at least in part by the profiles and / or the shapes of the tooth (10) and the notches (14) intended to receive said tooth (10) in order to determine a discrete length value.

5. Clasp (1) according to any of claims 1 to 4, characterized in that said indexing member (6) comprises a plurality of notches (14), in that said notches (14) comprise at least one contact structure (17), preferably a contact surface (17), and in that said tooth (10) comprises a bearing surface (19) arranged to be in contact with said contact structure (17) and to slide over said contact structure (17) during a displacement of the movable part (2), resulting in the lengthening and / or the shortening of the useful length of the wristband.

6. Clasp (1) according to any of the preceding claims, characterized in that each of the angles (α, ß) is greater than 10°.

7. Clasp according to any of the preceding claims, characterized in that said movable part (2) comprises a carriage (3) and in that said tooth (10) is arranged relative to the carriage (3) so as to be displaceable in a direction having a radial component, the radial component of the displacement allowing said tooth to slide over a bearing structure (17) of a notch (14) and to disengage from said notch (14) in which said structure (10) is positioned.

8. Clasp according to any of the preceding claims, characterized in that said indexing member (6) and said tooth of the movable part (2) are arranged such that the force in the longitudinal direction, preferably a push, required to achieve the displacement of the movable part (2) that serves to shorten the wristband length, is less than the force, preferably a pull, required to achieve the displacement of the movable part (2) that serves to lengthen the wristband.

9. Clasp according to any of the preceding claims, characterized in that said adjusting device (2-8) does not have a locking mechanism for blocking the length adjustment in at least one direction of the wristband length and / or an activation member such as a push element, a pull element and / or a slide, said activation member being intended to unblock a locking mechanism in order to allow the length to be adjusted in at least one direction of the wristband length.

10. Clasp (1) according to any of the preceding claims, characterized in that said length adjustment is a discontinuous fine length adjustment, in discrete length values.

11. Clasp (1) according to any of the preceding claims, characterized in that it is arranged so as to allow the length adjustment when the clasp is in an open position as well as when the clasp is in a closed position.

12. Clasp (1) according to any of the preceding claims, characterized in that said notch comprises a flank (17) and said tooth comprises a flank (19), and in that said flanks (17, 19) are planar and inclined with respect to the displacement direction of the movable part.

13. Clasp (1) according to any of the preceding claims, characterized in that the tooth (210) and said notch (214) have inclined flanks and / or profiles so as to allow the tooth (210) to be disengaged from its notch (214) when a force in the longitudinal direction, i.e. a pull or a push, is exerted on the movable part (202).

14. Clasp (1) according to any of the preceding claims, characterized in that the stop structure (5) comprising the tooth 10 is housed so as to be able to perform a translational movement, preferably a rectilinear translational movement, even more preferably a translational movement along a radial axis.

15. Wristwatch comprising the clasp (1) according to any of the preceding claims.

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