The present invention pertains to metal sleeve for a folding clasp of a wristwatch.

In particular the invention pertains to metal sleeves for the so called a deployment clasp, also called the deployant. A rigid sleeve is a rigid band, such as a metal band, optionally forming a closed loop.

The deployant was invented by Louis Cartier (the grandson of the founder) in 1910. The name comes from the French word deployant, which means to unfold, extend, or unfurl. The deployant extends the life of straps because once it is fitted to the correct length, the strap need not be fiddled around with every time the watch is put on and taken off. One advantage of a deployant clasp is that it makes the watch much harder to drop even when unbuckled, as the watch remains an unbroken loop around the wrist, so even if the watch head should slip from your hand, the watch is unlikely to leave your wrist. The deployant is for the above reason commonly adopted in high end wrist watches, such as the popular brand 'Rolex' . A deployant usually comprises a first blade and a second blade designed to fold over or into one, wherein the first and second blades are hinged to each other around an axis and can reversibly lock to each other. While the deployant has evolved over time the basic features of the deployant remain the same. More recent versions of the deployant may include a link adjusting element for the bracelet EP3329796B1 or locking element provided to the bracelet links EP2644050B1. A butterfly deployment clasp is also popular.

The near universal nature of, and the broad adoption of, the deployant in high-end wrist watches has come at a cost. Over many decades both friendly tricksters and fiendish thieves have, through practice with the clasp type, developed techniques of diversion and manipulation by which means the deployant can be opened and the watch can be taken in a manner that is largely unnoticed .

It is an aim of this invention to secure high-end watches provided with a folding clasp in the bracelet of a watch against theft, or at least to delay any attempt at the illicit acquisition thereof.

To this end the invention provides, according to a first aspect thereof: An anti-theft assembly of comprising a rigid sleeve; and a wristwatch comprising a wrist bracelet provided. The bracelet being provided with a folding clasp. Said folding clasp comprises a first blade; and a second blade. The first and second blades are hinged to each other around an axis for allowing the first and second blade to fold over or into each other for closing said clasp. The sleeve itself comprises two openings on opposite faces together forming a through hole dimensioned such that the sleeve removably slidably fits onto and over the folding clasp over the hinge between the first and second blades when they are folded over one another, so that the first and second blades extend through the through hole when, in use, the clasp is closed. The through hole is further dimensioned such that the first and second clasp are prevented from moving apart for opening said clasp when the sleeve is fitted onto the folding clasp. That is to say, the height of the through hole is chosen such that the first and second blades cannot move apart, so that the clasp assumes an open position, in which the first and second blades are unfolded. In one example, the sleeve comprises two first lateral walls wherein a distance between the outer surface of each of these two first lateral walls is substantially equal to the width of the bracelet. In such case, each wall of the two first lateral walls is provided with a protrusion extending away from, such as substantially perpendicular to, the outer surface of said lateral wall in an outward direction for allowing a user to manually reversibly remove the sleeve from the clasp by sliding the sleeve in a direction along the wristband. That is to say, in practice a user will be able to manually engage, such as with thumb and index finger, the sleeve by these protrusions so as to reversibly slide the sleeve onto the closed clasp between the users skin and a portion of the bracelet. This feature beneficially allows the security assembly to be disassembled easily by a wearer while under duress, whereas it simultaneously provides for an unexpected obstacle for those instances of thieving that merely consist of a slight of hand. The protrusions may be at least partially spherical as this provides for a more rapid tactile recognition of the sleeve allowing the user to differentiate the sleeve from other bracelet components by touch alone, making the sleeve more easily removable for the user. The shape also allows for a better grip by nail .

The rigid sleeve is designed to be able to slide over the hinge between allows the rigid sleeve to be fully removed from the watch and is thus and its design may therefore fully exclude any guide tracks on or extending through its first lateral walls, for receiving and guiding lateral portions of the clasp or bracelet. This design also does not require a clasp to be provided with any form of lateral recesses, which would otherwise trade its integrity for the ability transfer sleeve both blades onto a single one in order to facilitate the opening and closing thereof.

Preferably, the sleeve is formed as a singular piece of metal, that is to say that all features of the sleeve are integrally formed. This allows for ease of manufacturing. Most preferably the bracelet comprises metal links, wherein the metal of the sleeve is substantially identical to the metal of links of the bracelet. This choice of material largely prevents that movement of the sleeve with respect to the clasp and vice versa will cause scratches. This is particularly beneficial for instances in which softer metals or alloys are used, such as the ones comprising gold. Some examples are Gold-silver-copper alloys, gold-silver alloys, gold-copper alloys, and pure gold. By providing the sleeve of the same material the sleeve is furthermore less noticeable, at least to uninitiated thieves, as same material camouflages the sleeve against the bracelet of the watch. The benefit of camouflage would also apply for stainless steel bands and stainless steel bracelet links.

In order to prevent the accidental loss of the sleeve the sleeve may comprise two second lateral walls that together with the two first lateral walls define the through hole. One of the second lateral walls comprises a protrusion extending from an inner surface of said second lateral into the through hole for engaging with the a first blade or second blade of the clasp when, in use, the clasp is closed. This protrusion causes additional resistance against the sliding motion that would allow the sleeve to become disassembled from the clasp/wristwatch . Separately from the above the sleeve and clasp can be either of substantially the same material, or the clasp can be of a material having a higher hardness than the sleeve. This also prevents scratching of the clasp and ensures the durability of the wristwatch. It is noted that various methods of determining the hardness of metals have been developed, most of which involve the measurement of the size of an indentation on the surface of the material in relation to the force used to make the indent. The first widely used system was proposed by the Swedish engineer Johan Brinell in 1900, involving a spherical indenter. The large size of the resulting indentation and possible damage to the test piece limits the usefulness of the Brinell method. An alternative method was developed by two engineers at the British company, Vickers, in 1921. The Vickers test has a number of advantages. It produces an accurate number by measuring microscopically the diagonals of a diamond-shaped impression. It can be used for all metals and covers a wide range of hardness. The unit of hardness given by the test is known as the Vickers Pyramid Number or Vickers Hardness (HV) with units of kgf/mm ² . For SI purists, this unit (kgf/mm ² ) can be converted into MPa (megapascals) by multiplying by the gravitational acceleration of 9.807. Comparison with some commonly used and related metals is shown herein below.

Metal HV (kg/mm2)

Aluminum 16

Copper 35

Gold 25

Iridium 200

Iron 62

Palladium 50

Platinum 48

Silver 26

In one example the sleeve can comprises two second lateral walls that together with the two first lateral walls define the through hole. One of the second lateral walls may then comprises a protrusion extending from an inner surface of said second lateral into the through hole for engaging with the a first blade or second blade of the clasp. Such protrusion may be obtained by striking an indentation into an outer surface of the preformed sleeve, such as with a sharp pointed object. This example reliably increases the static friction of the sleeve on the clasp, while no additional material needs to be provided, often gold, to form a friction element. This is of great benefit to both cost and ease of manufacture. In this case the protrusion of the one second lateral walls corresponds to an indentation on an outer surface of said one second lateral wall.

It was also found that a wearer will present no discomfort if the distance between the outer surfaces of the two second lateral walls is substantially equal to a thickness of at least one link of the links of the bracelet. That is to say the distance may vary between 50-150%, preferably 80-120% of the thickness of a link .

Usually, a clasp, that is to say its first and second blades, will be curved along its length to (comfortably) follow the curvature of a human wrist when the clasp is closed. It was however found that, by making having no inner surface portion of said sleeve corresponds to said clasp curvature, the assembly is more resistant against automatic disassembly. More in general, the sleeve is uncurved, that is to say substantially entirely straight, along its length. It is assumed that this prevents accidental sliding of the sleeve as a result of the skin' s elastic deformation.

In some instances the clasp may be part of a butterfly deployant, also known as a double clasp. In such event the clasp is mirrored by a second folding clasp on the bracelet. In such a case the assembly may further comprise another clasp, which is substantially identical to the clasp, for being fitted onto the second clasp, and wherein the first sleeve and second sleeve differ in their connector portions which each comprises for being mutually connectable when each sleeve is fitted over its corresponding clasp.

According to a second aspect of the invention there is provide a rigid sleeve of the assembly according to the first aspect of the invention.

The sleeve may be provided with a connector portion, such as articulated at the protrusion, for connecting to another sleeve.

According to a third aspect of the invention there is provided a metal casting mold for casting the rigid sleeve. In such a casting mold the sleeve may be formed as singular metal piece with the exception of any articulated connector portions. However any articulated connector portions, if present on the sleeve, are to be provided separately.

Finally, according to a fourth aspect of the invention, there is provided a method of forming a rigid sleeve comprising the step of: - casting the sleeve in a mold; and optionally - indenting an outer surface of the sleeve such that an internal protrusion is formed on the opposite inner surface of said outer surface .

The invention will hereinafter be elucidated by reference to a set of drawings:

Fig. 1 clasp and sleeve;

Fig. 2 first cross section sleeve;

Fig. 3 second cross section sleeve;

Fig. 4 third cross section sleeve;

Fig. 5 assembly on wrist; and

Fig. 6 assembly of a double clasp and double sleeves.

Figure 1 shows the components of an anti-theft assembly 1000 according to the invention. The assembly is one of a wristwatch 100 and a sleeve 1. Said wristwatch comprises a bracelet 201 which is interrupted by a folding clasp 10 that itself forms part of the bracelet. This clasp here assumes the form of a deployant. That between an open and closed position the bracelet changes in length, but remains uninterrupted. The clasp has a first blade 11 and a second blade 12. These first and second blades are hinged to each other around an axis X for allowing the first and second blade to fold over each other to close the clasp 10. It is noted that Figure 1 shows the clasp as open. The sleeve is rigid and integral entirely made of an 18kt gold alloy of gold, silver and copper. The sleeve comprises two openings on opposite faces together forming a through hole 2. This is best seen in Figure 3 which represent a 'horizontal' cross- sectional view B-B of the link which is perpendicular to the 'vertical' cross-sectional view A-A, which is itself represented in Figure 2. The through hole 2, as defined by the inner surface of the sleeve, is dimensioned so that the sleeve slidably fits onto the folding clasp such that the first and second blades extend through the through hole 2 and are prevented from moving apart for opening said clasp. This is best seen in Figure 4 which shows a third cross-sectional view C-C in which the clasp 10 extends through the through hole 2. Figure 4 shows that the blades of the clasp are prevented from moving apart while the sleeve 1 is assembled with the watch 100.

Figure 2, as mentioned before, shows 'vertical' cross-sectional view A-A. In this Figure the sleeve is shown to comprise two first lateral walls 3.1, 3.2 wherein the distance W between the outer surface of each of these two first lateral walls is substantially equal to the width of the bracelet. Substantially equal is between 95-105% of the width of the bracelet. This also prevents that pulling or twisting of the wristwatch, while on a wrist, will cause the sleeve to jab into the skin of the user with its outer edges. In Figure 2 it can clearly be seen that each wall of the two first lateral walls is provided with a protrusion 4 extending from the outer surface of said lateral wall in an outward direction for allowing a user to manually reversibly remove the sleeve 1 from the clasp 10 by sliding the sleeve in a direction along the wristband. The reversible sliding motion is shown by arrow S, wherein in use such sliding of the sleeve occurs between the skin of the user U and the bracelet 20.

Figure 2 also shows that the sleeve has two second lateral walls 3.3, 3.4 that together with the two first lateral walls 3.1, 3.2 define the through hole 2. One of the second lateral walls, here the top wall 3.3, comprises a protrusion 5 extending from an inner surface of said second lateral 3.3 into the through hole 2 for engaging with the a first blade or second blade of the clasp. Figure 4 shows that the clasp is curved to follow the curvature of the wrist. In this example the sleeve 2 and watch are assembled such that the claps 10 curves towards the protrusion 5. In this manner of assembly the protrusion may be smaller than it ordinarily would have to be. A protrusion provided by manner of indentation will have angles that are less sharp, thus further reducing scratching. It is noted that in Figures 2 and 4 the protrusion 5 is formed through indentation of second lateral wall 3.3. This protrusion 5 is however entirely optional .

Figure 2 further shows a distance H between the outer surfaces of the two second lateral walls 3.3, 3.4. Figure 5 shows that this distance H is at least equal to half the thickness of at least one link of the links of the bracelet, and no larger than one and a half times said thickness. This improves comfort of wear .

Accordingly, there is described herein that the rigid sleeve 2 of the invention is a metal band, preferably of gold or a gold alloy, that forms a closed loop with a width W and a length L each being greater than a height H of said band. W, H and L are for reference shown in Figures 2-4. The closed loop, that is to say an uninterrupted loop, is substantially rectangular in shape. Furthermore, the two first and second walls each form a substantially flat outer and inner surface with the exception of a plurality of surface protrusions, of which two protrusions project outwardly from the sleeve, each from one of the two first walls for enabling manual engagement, and optionally one protrusion projecting from an inner surface of the sleeve.

The term rigid may further be understood to mean that the sleeve material and wall thickness is chosen such that plastic deformation of said sleeve under the outward pressure of an opening folding clasp, such as a deployant, is prevented and, wherein the material is non-elastic. Rubber would for example be a particularly unsuitable material for the purpose of the invention .

Figure 6 shows the assembly (1000' ) of Figure 1 with one key difference, namely the bracelet (not shown, but customary) comprises a another folding clasp 10.2 that is substantially identical to the folding clasp 10 as previously discussed. In this particular example the bracelet is fitted with a butterfly deployant, which would comprise two such folding clasps mirrored and opposite each other as part of the bracelet. In such a case one might apply the same invention twice, in that the other clasp 10.2 might be fitted with another sleeve 1.2. Such a sleeve could then be identical to the sleeve 1 provided to clasp 10. However, in some cases the sleeves may move independently from each other. In opening the deployant both sleeves would need to be slid onto a single clasp, the other clasp must then be opened, before both sleeves can be removed.

In order to allow both sleeves to slide in a singular motion, the sleeves may each be provided with a connector portions 4.1, 4.2 that cooperate with each other for reversibly connecting the sleeve 1 and other sleeve 1.2. This would allow the sleeves to co-slide, which facilitates their removal and prevents the accidental loss of a sleeve.

The connector portions 4.1, 4.2 don't need to be the same, but they could be. The person skilled in the art would know that there are various ways to go about this.

In one embodiment an articulated leg 4.2 is provided to each of the protrusions 4 of the sleeve 1. Each leg could being designed to snap fit with a space or recess 4.1 defined between an at least partially spherical part of the protrusion 4' and the outer surface of the first lateral wall of the other sleeve 1.2. Here 4.1 and 4.2 form the connector portions.