CN115605111A

CN115605111A - Extensible clasp with folding clasp for a bracelet, in particular for a watch

Info

Publication number: CN115605111A
Application number: CN202180038070.4A
Authority: CN
Inventors: P·帕乔拉克; R·纪贡
Original assignee: G&f Lord Co ltd Chanel Branch
Current assignee: G&f Lord Co ltd Chanel Branch
Priority date: 2020-05-28
Filing date: 2021-05-21
Publication date: 2023-01-13
Also published as: CH717459A1; EP4157026B1; EP4157026A1; WO2021240317A1

Abstract

The invention relates to an extensible clasp with a folding clasp (10: a support (12, 112 with two longitudinal edges (14 a, 14b, 114a, 114b); at least one flexible sheet (17; at least one pivoting flap (20 a, 20b, 120a, 120320) with a proximal portion hinged to one end of said support by means of a lever (21 a, 21b 121a, 121221), and a distal portion designed to be connected to one of the halves of the wristband. The catch (10. The flexible tab is designed to first exert a force on the at least one pivoting tab to press the pivoting tab against the support (12.

Description

Extensible clasp with folding clasp for a bracelet, in particular for a watch

Technical Field

The present invention relates to the field of wristbands, in particular wristbands for watches. More particularly, the present invention relates to a wristband clip with a folding buckle that enables the wristband to be adjusted for comfort.

Background

Stretchable clasps for adjusting wristbands, in particular wristbands for watches, for comfort are well known and various solutions already exist.

For example, CH705149 discloses a clasp with a folding buckle comprising a central support, a first and a second pivoting flaps hinged at respective ends of the central support and designed to be folded back onto said support. The hook also includes a fastening member disposed on at least one of the first and second pivoting tabs. The fastening members are designed to move longitudinally along the corresponding pivoting tabs and to be locked in different positions along said tabs.

EP1464245 discloses a snap hook with a fold buckle comprising a curved lower arm and a curved upper arm, locking means and linking means at one of the ends of the arms to link the arms together in an articulated manner. One end of the upper arm is mounted on a slide of the lower arm to move relative to the lower arm so as to occupy at least two positions in which a head rigidly connected to the upper arm can engage in one or the other of two cutouts arranged on the lower arm.

EP3412168 discloses a clasp for a wristband comprising a first and a second sheet. The first panel is hingedly connected at a first end to the second panel between a closed position in which the second panel is folded back onto the first panel and an open position in which the second panel is disengaged from the first panel. The hook comprises an adjustment device designed to adjust the position of the second panel relative to the first panel in the open position. The adjustment means comprises a slot machined in the second plate and a shaft passing through the slot rigidly connected to the first plate. The push button is mounted on the shaft to enable the second sheet to be moved relative to the first sheet by the push button.

These hooks have the disadvantage that they comprise many parts, which leads to their complex manufacture and has a negative impact on production costs and reliability.

Disclosure of Invention

It is therefore an object of the present invention to propose an extensible hook that is simple to manufacture and inexpensive to produce.

Another object of the invention is to propose a reliable extensible clasp.

These objects are achieved by an extensible clasp with a folding clasp for wristbands comprising:

-a support with two longitudinal edges,

at least one flexible sheet rigidly connected to the support, the flexible sheet having at least one end portion,

-at least one pivoting blade with a proximal portion hinged to one end of the support by means of a bar, and a distal portion designed to be connected to one of the halves of the wrist strap, and

an indexing mechanism for adjusting the wristband for comfort, designed to move the lever with respect to the support or with respect to said at least one pivoting blade, so as to position the lever in one of at least two index positions.

The flexible tab is designed to first exert a force on the at least one pivoting tab to press the pivoting tab against the support and hold the clasp in a closed state, and second lock the lever in the indexed position.

According to one embodiment, the force exerted by the end portion of the flexible sheet is transferred to the pivoting sheet by means of a roller rotatably mounted on the pivoting sheet. The other end of the support has means for attaching the other half of the wristband.

According to one embodiment, the extendable clasp has first and second pivot tabs, each of which has a proximal portion and a distal portion. The proximal portions of the first and second pivoting tabs are hingedly connected to the first and second ends of the support member by first and second rods, respectively. The distal portions of the first and second pivot tabs are designed to be connected to the two halves of the wristband.

The indexing mechanism is designed to move the first and second levers relative to the support or relative to the first or second pivot tab, respectively, so as to position each of the first and second levers in one of at least two index positions. The flexible tab is designed to first exert a force on the first and second pivoting tabs to press them against the support and hold the clasp in the closed state, and second to lock the first and second levers in the respective indexed positions.

According to one embodiment, each of the first and second pivoting tabs has a roller arranged to abut against the first and second end portions of the flexible tab, respectively, when the snap hook is in the closed state.

According to one embodiment, each of the distal portions in the first and second pivot tabs has means for attaching one of the halves of the wristband. Each proximal portion of the first and second pivoting tabs includes a roller designed to bend and roll along a corresponding end portion of the flexible tab when a force is applied on the attachment member in a direction tending to bring the snap hooks into the deployed state.

According to one embodiment, the support has four slots arranged at respective ends of each of the two longitudinal edges of the support. The first and second rods traverse the first and second pivot tabs, respectively. The two ends of each rod are located in two opposite slots. The shape of the opposing two grooves defines the at least two index positions.

According to one embodiment, each of the four slots is curved and passes all the way through one of the longitudinal edges of the support.

According to one embodiment, each of the first and second pivoting tabs has a body and two arms that extend lateral edges of the body to form windows to enable each pivoting tab to pivot to enable the corresponding lever to come into contact with the flexible tab.

According to one embodiment, the end portion of each of the two arms has a first through hole arranged opposite each other and receiving two sections of a corresponding rod. The end portion of each of the two arms also has a second aperture disposed opposite each other and receiving an end of an axle about which the roller is pivotally mounted.

According to one embodiment, the support has four holes arranged at respective ends of each of the two longitudinal edges. The two ends of each rod are located in two opposing holes. Each of the first and second pivoting tabs has two arms, each arm having a first slot, the slots being disposed opposite each other and across which the corresponding bar traverses. The two sections of the lever are in two first opposite slots and the shape of the first slots is such that, when the corresponding pivoting tabs are brought into a predetermined angular position with respect to the support, the two sections of the lever can move along the slots in order to move the lever from a first to a second index position.

According to one embodiment, each of the first and second pivoting tabs has a roller pivotably mounted on the shaft. Each roller is arranged to abut against a first and second end portion of the flexible sheet, respectively, when the snap hooks are in the closed state. Each of the two arms of the first and second pivoting tabs has a second slot, said slots being arranged opposite each other and across which the respective ends of the axles of the rollers cross.

According to one embodiment, each of the first and second pivoting flaps has a link member with a through hole across which the respective bar of said first and second pivoting flaps traverses. The link member also has two lugs, each of which has a through hole. A first section and a second section of the axle of the roller are disposed in respective holes in each of the lugs.

According to one embodiment, the shaft of the respective lever and roller of each of the first and second pivoting tabs is designed to move together along the first and second slots, respectively, when the first and second pivoting tabs are pivoted, such that the force exerted by the first and second end portions of the flexible tab on the roller of the first and second pivoting tabs, respectively, remains constant when the snap hook is in the closed state, regardless of the indexed position of the first and second pivoting tabs.

Another aspect of the invention relates to a wristband having an extensible clasp as described above.

Another aspect of the invention relates to a watch comprising the above wristband.

Drawings

Exemplary embodiments of the present invention are set forth in the description, with reference to the accompanying drawings, in which:

figure 1 is an exploded view of an extensible clasp with a double folding buckle for wristbands, with a mechanism for adjusting the wristband for comfort, according to a first embodiment;

fig. 2 is a perspective view of the clasp of fig. 1 in a closed condition and a first position of rotation;

fig. 3 is a view similar to fig. 2, with the catch in a second indexed position;

fig. 4 is a perspective view of the clasp of fig. 2, with the two pivoting flaps unfolded;

figure 5 is a cross-sectional view of figure 4;

fig. 6 is a view similar to fig. 5, with both pivoting tabs pivoted through about 270 ° about their respective pivot axes relative to their positions when the clasp is in the closed condition shown in fig. 2;

figure 7 is a perspective view of one of the pivoting flaps of figure 6, in a first position of rotation with respect to the central support;

figure 8 is a view similar to figure 7, with the pivoting tab in a second indexed position with respect to the central support;

FIG. 9 is a partial view of FIG. 8;

fig. 10 is an exploded view of an extensible clasp with a double folding buckle for wristbands according to a second embodiment, with a mechanism for adjusting the wristband for comfort;

fig. 11 is a perspective view of the clasp of fig. 10 in the closed condition and in the first position of rotation;

fig. 12 is a view similar to fig. 11, with the catch in a second indexed position;

fig. 13 is a perspective view of the clasp of fig. 12, with the two pivoting flaps unfolded;

fig. 14 is a perspective view of the clasp, with the two pivoting tabs pivoted through about 270 ° about their respective pivot axes relative to their positions when the clasp is in the closed condition shown in fig. 11;

figure 15 is an enlarged perspective view of figure 14, showing the articulation of the first pivoting tab with the pivoting tab in a first indexing position;

fig. 16 is a view similar to fig. 15, with the pivoting tab in a second indexed position;

fig. 17 is a perspective view of an extensible clasp with a single folding clasp for wristbands according to a third embodiment, with the clasp in the closed condition;

fig. 18 shows the clasp of fig. 17, with the pivoting tab unfolded; and is

Fig. 19 is a perspective view of an extensible clasp with a single folding clasp for wristbands according to a fourth embodiment, with the clasp in the closed condition.

Detailed Description

According to a first embodiment shown in fig. 1 to 9, the extensible clasp 10 has a double fold buckle (commonly known as a butterfly fold buckle) and (as shown in fig. 1) comprises for this purpose a central support 12 and a first and a second pivoting flaps 20a, 20b hinged to respective ends of the central support 12 by means of a first and a

second rod

21a, 21b, respectively (fig. 4). The central support 12 has two

longitudinal edges

14a, 14b (fig. 2) that are slightly arched to fit part of the wrist contour.

The two

longitudinal edges

14a, 14b are linked together by a portion 18 acting as a sheet support, the flexible sheet 17 being mounted on this portion 18. For example, a central portion of the flexible sheet 17 may be fastened to the sheet support 18 using fastening elements 19 (in particular screws). For this purpose, the central portion of the flexible sheet 17 has a through hole 17a and the sheet support 18 has a threaded hole 18a designed to fasten the central portion of the flexible sheet 17 against the upper surface of the sheet support 18. The flexible sheet 17 is fastened so as to extend along the

longitudinal edges

14a, 14b of the central support.

The central support 12 has four

slots

16a, 16b;16c, 16d arranged at respective ends of each of the two

longitudinal edges

14a, 14 b. Each slot passes all the way through one of the longitudinal edges and has a curved shape with a semi-cylindrical portion at each end, defining two index positions. However, the slot may have different shapes depending on the variant, and there may be more than two index positions to enable more precise adjustment when adjusting the wristband for comfort.

The

curved slots

16a, 16b are arranged facing each other at a first end of the central support 12, so as to receive the ends of the levers 21a of the first pivoting flaps 20 a; and the

curved slots

16c, 16d are arranged facing each other at the second end of the central support 12 so as to receive the ends of the levers 21b of the second pivoting flaps 20 b. The head of each rod, positioned at one of its ends, and the cap 22 mounted at its other end prevent any axial travel of the rod with respect to the central support 12. By the action of the flexible tab 17, the lever can be held against either of the cylindrical portions of each of the curved slots representing the first and second indexed positions.

As described below, and in particular as shown in fig. 4, each pivoting

tab

20a, 20b has a body 31 and two arms 34, the two arms 34 extending the lateral edges of the body 31 to form a window 32, thereby enabling each pivoting

tab

20a, 20b to pivot, thereby enabling the

corresponding lever

21a, 21b to come into contact with the flexible sheet 17. The end portion of each of the two arms 34 has a through hole 35 arranged opposite each other and receiving two sections of the

corresponding rod

21a, 21 b.

Each

pivoting tab

20a, 20b also has a roller 24 mounted between two arms 34. More specifically, the roller 24 is designed to rotate about an axis 25. The shaft is formed by a notched tube 27 and a slotted pin 26, the pin 26 fitting into the tube 27 so that the rollers 24, the tube 26 and the pin 25 are centered together. The ends of which are located in two further holes 36 in the end portion of each of the two arms 34, close to the through hole 35.

Each pivoting

flap

20a, 20b has a distal portion provided with an extension 40 with a through hole 42, a bar 44 being arranged in the through hole 42, the end of the bar 44 being fastened to an attachment member 45, the attachment member 45 being designed to be linked to the first and second half of the wrist strap.

Referring to fig. 2, the extendable hook 10 is in a closed state in which the

respective levers

21a, 21b of the first and second pivoting flaps 20a, 20b are arranged in a first turning position to tighten the wristband. In this state, the members 45 attaching the halves of the wrist band are positioned close to each other.

Referring to fig. 3, the extendable hook 10 is in a closed state with the respective stems 21a, 21b of the first and second pivoting flaps 20a, 20b disposed in a second indexed position so that the wristband can be adjusted for comfort. In this state, the members 45 attaching the halves of the wrist band are positioned away from each other.

Fig. 4 to 8 show different sequences of movement of the first and second pivoting flaps 20a, 20b relative to the central support 12 in order to transfer the catch 10 from the first state, as shown in fig. 2, to the second state, as shown in fig. 3. When worn, the indexing mechanism does not allow the wearer to adjust the wristband for comfort. To adjust the wristband for comfort, the wristband must first be removed from the wrist.

As shown in fig. 4 and 5, the first and

second pivoting pieces

20a, 20b are unfolded first. The pivoting tab is additionally pivoted through approximately 180 deg. to achieve the hook-on condition shown in fig. 6. This additional pivoting is achieved by a window 32 (fig. 4) in each

pivoting tab

20a, 20b, through which window 32 the respective first and second end portions of the flexible tab 17 are arranged.

As shown in fig. 6, the

respective levers

21a, 21b of the first and

second pivoting pieces

20a, 20b come into contact with the end portions of the flexible piece 17. Thus, it is only necessary to exert a small force on each of the pivoting

tabs

20a, 20b in a direction perpendicular to the bearing surface of the flexible sheet 17 on which the

lever

21a, 21b of each pivoting tab rests, in order to move the corresponding lever from the first cylindrical portion of the curved slot 16d shown in fig. 7 to the second cylindrical portion of the curved slot 16d shown in fig. 8, in order to switch from one of the two indexed positions to the other.

It should be noted that the first and second pivoting tabs can also be moved from one of the two indexed positions to the other by simply pivoting less than 90 ° from the closed condition of the snap hook. In fact, starting from the snap hook in the condition shown in fig. 5, in which the rollers 24 of the first and second pivoting flaps 20a, 20b rest on the corresponding bearing surfaces of the flexible flaps, the transition from the first to the second indexed position can be obtained by applying a force on one and/or the other of the two pivoting flaps towards the flexible flap 17.

Nevertheless, the force exerted on the first and

second pivoting pieces

20a, 20b must be significantly greater than when starting from the hooked state shown in fig. 6, and thus it is difficult to adjust the wristband for comfort.

According to another embodiment, as shown in fig. 10 to 16, the hook 100 has a central support 112 with two

longitudinal edges

114a, 114b (fig. 11) and a flexible sheet 117 rigidly connected to the central support 112, and the flexible sheet 117 is arranged between the two

longitudinal edges

114a, 114b and alongside them. Four

apertures

116a, 116b, 116c, 116d are arranged at respective ends of each of the two

longitudinal edges

114a, 114b of the central support.

The hook 100 also has a first pivot tab 120a and a second pivot tab 120b (fig. 13), each of the first pivot tab 120a and the second pivot tab 120b having a proximal portion and a distal portion. The proximal portions of the first and

second pivoting tabs

120a,120b are hinged to the first and second ends of the central support 112 by means of first and

second rods

121a, 121b, respectively, the ends of the first and

second rods

121a, 121b being mounted in two opposite ones of the four

holes

116a, 116b, 116c, 116d of the

longitudinal edges

114a, 114b of the central support 112.

The distal portions of said first and second pivoting flaps 120a,120b are provided with an extension 140 with a through hole 142, a bar 144 being arranged in this through hole 142, the ends of the bar 144 being fastened to attachment members 145, which attachment members 145 are designed to be linked to the first and second halves of the wrist strap.

Referring to fig. 10, each of the first and second pivoting pieces has two arms 134, each of the arms 134 having an end portion. Each of the end portions has a first slot 138, which are arranged opposite each other and across which the

corresponding rod

121a, 121b crosses. The head of each rod, positioned at one of its ends, and the cap 122 mounted at its other end prevent any axial travel of the rod relative to the central support 112.

The two sections of the bars are in two opposite first slots 138 and the shape of the first slots is such that when the

corresponding pivoting tabs

120a,120b are brought into a predetermined angular position with respect to the central support 112, the two sections of the

bars

121a, 121b can move along said slots 138 in order to move said

bars

121a, 121b from the first to the second index position.

As shown in fig. 15 and 16, two sections of each bar 121a (only bar 121a of one of the pivoting flaps is shown in these figures) have flat portions 123 and the two opposite first slots 138 have two semicircular ends separated by a straight slit 138 a.

As shown in fig. 14 to 16, this predetermined angular position preferably corresponds to the position of the first and

second pivoting tabs

120a,120b after they have been rotated by an angle greater than 250 ° about their respective axes of rotation, for example about 270 ° relative to their position when the catch 100 is in the closed condition.

For this purpose, as with the snap hook according to the first embodiment shown in fig. 1 to 9, each of the first and

second pivoting pieces

120a,120b has a window 132 (fig. 14) through which an end portion of the flexible piece 170 can pass, thereby enabling each pivoting

piece

20a, 20b to pivot and enabling the snap hook to be shifted to the state shown in fig. 14.

When the first and

second pivot tabs

120a,120b are in this predetermined angular position, the flat 123 of the corresponding section of the rod located in one of the semi-circular ends of the slot 138 is aligned with the straight slot 138a, thereby enabling the section to move along this slot and be located in the other semi-circular end of the slot 138.

When the snap 100 is in the closed state, the first and second end portions of the flexible sheet 170 exert a force against the first and

second bars

121a, 121b, respectively, to retain the corresponding section of each bar in one or the other of the semicircular ends of the slot 138, so as to lock the snap in one or the other of the two indexed positions.

As shown in fig. 10, each of the first and

second pivot tabs

120a,120b has a roller 124 pivotably mounted on an axle 125. The shaft is formed by a notched tube 127 and a slotted pin 126, the pin 126 fitting into the tube 127 so that the rollers 124, tube 126 and pin 125 are centered together. When the snap hook is in the closed state, the rollers are arranged to abut against the first and second end portions of the flexible sheet 117, respectively. Each of the two arms 134 of the first and

second pivoting tabs

120a,120b has a second slot 137 disposed opposite each other and traversed by a respective end of the shaft 125 of the roller 124.

Each of the first and

second pivoting pieces

120a,120b has a link member 128 with a through hole 130, and the

respective levers

121a, 121b of the first and

second pivoting pieces

120a,120b cross the through hole 130. The link member 128 also has two lugs 129, each of which has a through hole 129a. The ends of the axles 125 of the rollers 124 are disposed in respective holes 129a in each of the lugs 129. The first and second sections of the axle 125 of the roller 124 are disposed in respective holes 129a in each of the lugs 129.

The

respective levers

121a, 121b of each of the first and

second pivot tabs

120a,120b and the shaft 125 of the roller 124 are designed to move together along the first and

second slots

138, 137, respectively, as the first and

second pivot tabs

120a,120b pivot such that the force exerted by the roller 124 on the central support 112 when the snaps are in the closed condition remains constant regardless of the indexed position of the first and

second pivot tabs

20a, 20 b.

According to another embodiment shown in fig. 17 and 18, the extensible clasp 200 with a single folding buckle has a support member 212, a flexible sheet 217 mounted on the support member and extending along its

lateral edges

214a,214b, and a pivoting sheet 220, the pivoting sheet 220 being hinged by means of a lever 221 to a first end of the support member 212 and cooperating with an end portion of the flexible sheet 217 by means of a roller 224, the roller 224 being designed to press the pivoting sheet against the support member to keep the clasp in a closed state.

A first member 246 for attaching one of the halves of the wristband is arranged at the other end of the support 212 and a second member 245 for attaching the other half of the wristband is connected to the end of the pivoting sheet. The snap hook 200 also includes an indexing mechanism to move the pivot tab 220 relative to the support to one or the other of two indexed positions. This mechanism is the same as that described for one of the two pivoting tabs of the clasp in the embodiment shown in fig. 1 to 9.

According to the embodiment shown in fig. 19, the extendable clasp 300 with a single fold buckle includes an indexing mechanism for adjusting the wristband for comfort, which is arranged to move a lever (not shown) relative to the pivot tab 320 to position the lever in one of at least two index positions. The indexing mechanism has the same features as described in relation to the positioning of the lever of one of the two pivoting flaps of the clasp in the embodiment shown in figures 10 to 16.

Various modifications may be made to the extendable hook according to the present invention without thereby departing from the scope of the invention as defined in the appended claims. For example, the flexible sheet need not be continuous and may comprise two flexible portions spaced apart from each other and which are designed to exert a force on respective ones of the first and second levers of the pivoting sheet.

List of reference numerals

An extensible hook 10;100, respectively; 200;300

A central support 12;112;212

Longitudinal edges

14a, 14b;114a, 114b;214a,214b

The

grooves

16a, 16b;16c, 16d

Holes

116a, 116b, 116c, 116d

A flexible sheet 17;117;217

Fastening hole 17a

Sheet support 18

Fastening hole 18a

Fastening element 19

First and

second pivoting pieces

20a, 20b;120a,120 b;220;320

The

rods

21a, 21b;121a, 121b;221 (rotation axis)

A cap 22;122

Plane part 123

A roller 24;124

A shaft 25;125

A pin 26;126 (with slit)

A tube 27;127 (with notch)

Link member 128

Lug 129

Hole 129a

Through hole 130

Body 31

A window 32;132

Rectangular shape

An arm 34;134

Proximal part

Through hole 35 for the axis of rotation

Holes 36 for rollers

Groove 137

Groove 138

Straight slit 138a

Distal portion

An extension 40;140

A through hole 42;142

A rod 44;144

A member 45 for attaching the half of the wristband; 145;246.

Claims

1. an extensible clasp with fold-over clasp (10:

-a support (12, 112 with two longitudinal edges (14 a, 14b, 114a, 114b, 214a,214 b),

-at least one flexible sheet (17,

-at least one pivoting flap (20 a, 20b 120a,120b 220) with a proximal portion hinged to one end of the support by means of a lever (21 a, 21b 121a, 121221), and a distal portion designed to be connected to one of the halves of the wristband

-an indexing mechanism for adjusting the wrist strap for comfort, designed to move the lever (21 a, 21b, 121a, 121b 221) with respect to the support (12) or with respect to the at least one pivoting tab (121 a, 121 b) in order to position the lever in one of at least two indexing positions,

the flexible tab is designed to first exert a force on the at least one pivoting tab to press the pivoting tab against the support (12.

2. The extendable clasp (200) of claim 1, wherein the force exerted by the flexible sheet (270) is transferred to the pivoting sheet (220) by means of a roller (224) rotatably mounted on the pivoting sheet; and wherein the other end of the support has means (246) for attaching the other half of the wristband.

3. The extensible clasp (10, 100) according to claim 1, comprising a first and a second pivoting flap (21 a, 21b, 121a, 121 b), each of which has a proximal portion and a distal portion, the proximal portions of said first and second pivoting flaps being hinged to a first and a second end of the support (12) respectively by means of a first and a second lever (21 a, 21b, 121121a, 121 b), respectively, the distal portions of said first and second pivoting flaps being designed to be connected to the two halves of the wrist strap,

the indexing mechanism is designed to move the first and second levers (21 a, 21b, 121a, 121 b) with respect to the support (12) or with respect to the first or second pivoting tab (120 a,120 b), respectively, so as to position each of the first and second levers in one of at least two indexing positions, and

the flexible tab (17, 170) is designed to exert a force on the first and second pivoting tabs (20 a, 20b, 120a, 120b) first to press the pivoting tabs against the support (12) and to keep the snap hook in a closed state, and to lock the first and second levers in respective indexed positions second.

4. An extensible clasp (10, 100) according to claim 3, wherein each of said first and second pivoting sheets (20 a, 20b 120a,120 b) has a roller (24, 124), said rollers (24, 124) being arranged to abut, when said clasp is in a closed state, against said first and second end portions of said flexible sheet (17.

5. The extensible clasp (10, 100) according to claim 4, wherein each distal portion of said first and second pivoting flaps (20 a, 20b 120a,120 b) has a member (45; and wherein each proximal portion of the first and second pivoting flaps (20 a, 20b 120a,120 b) comprises the roller (24.

6. The extendable clasp (10) according to any of the preceding claims, wherein the support (12) has four slots (16 a, 1694, 16 d; and wherein said first and second levers (21 a,21 b) cross said first and second pivoting tabs (20 a, 20 b), respectively, the two ends of each lever (21 a,21 b) being located in two opposite slots (16 a, 1694, 1695, 16 d), and the shape of said two opposite slots defining said at least two index positions.

7. An extensible clasp (10) according to the preceding claim, wherein each of said four slots (16 a, 16b,16c, 16 d) is curved and passes all the way through one of said longitudinal edges (14 a, 14 b) of the support (12).

8. The extendable clasp (10) according to any of claims 3 to 7, wherein each of the first and second pivoting tabs (20 a, 20 b) has a body (31) and two arms (34), the two arms (34) extending the lateral edges of the body (31) to form a window (32), the window (32) enabling each pivoting tab (20 a, 20 b) to pivot, thereby enabling the corresponding lever (21 a,21 b) to come into contact with the flexible tab (17).

9. An extensible clasp (10) according to the preceding claim and claim 4, wherein the end portion of each of said two arms (34) has a first through hole (35) arranged opposite each other and receiving two sections of the corresponding stem (21 a,21 b); the end portion of each of the two arms (34) also has a second bore (36) disposed opposite each other and receiving an end of an axle about which the roller (24) is pivotably mounted.

10. The extensible clasp (100) according to any of claims 1 to 5, wherein the support (112) has four holes (116 a, 116b, 116c, 116 d) arranged at respective ends of each of the two longitudinal edges (114 a, 114 b), the two ends of each rod (121 a, 121 b) being located in two opposite holes (116 a, 116b, 116c, 116 d); and wherein each of said first and second pivoting flaps (120 a,120 b) has two arms (134), each of said arms (134) having a first slot (138) arranged opposite to each other and across which the corresponding bar (121 a, 121 b) crosses; and wherein the two sections of the lever are in two first slots (138) opposite each other and shaped so that, when the corresponding pivoting tabs are brought into a predetermined angular position with respect to the support (112), the two sections of the lever (121 a, 121 b) can move along the slots (138) in order to move the lever (121 a, 121 b) from a first to a second indexing position.

11. The extendable hook (100) of claim 10, wherein each of said first and second pivoting tabs (120 a,120 b) has a roller (124) pivotably mounted on an axle (125), each roller (124) being arranged to abut against said first and second end portions of said flexible tab (117), respectively, when said hook is in a closed state; and wherein each of said two arms (34) of said first and second pivoting flaps (120 a,120 b) has a second slot (137) which are arranged opposite each other and across which the respective ends of said shafts (125) of said rollers (124) cross.

12. The extendable hook (100) of claim 11, wherein each of said first and second pivot tabs (120 a,120 b) has a link member (128) with a through hole (130), said respective stems (121 a, 121 b) of said first and second pivot tabs (120 a,120 b) crossing said through hole (130), said link member (128) further having two lugs (129), each of said lugs having a through hole (129 a), first and second sections of said shaft (125) of said roller (124) being disposed in said respective holes (129 a) of each lug (129).

13. The extendable hook (100) of claim 11 or 12, wherein the respective bar (121 a, 121 b) and the shaft (125) of the roller (124) of each of the first and second pivot tabs (120 a,120 b) are designed to move together along the first and second slots (138, 137), respectively, when the first and second pivot tabs (120 a,120 b) are pivoted, such that the force exerted by the first and second end portions of the flexible tab (117) on the roller (124) of the first and second pivot tabs (120 a,120 b), respectively, remains constant when the hook is in a closed state, regardless of the indexed position of the first and second pivot tabs (120 a,120 b).

14. A wristband comprising an extensible clasp according to any preceding claim.

15. A watch comprising the wristband of claim 14.