Arrangement for fastening a crystal of a timepiece

Abstract

The invention relates to a timepiece comprising a case and a crystal delimiting an interior volume in which a watch movement is arranged, the timepiece comprising a device for fastening the crystal to the case at the periphery of the crystal. The timepiece also comprises a device for connecting the crystal, comprising at least one support stud which is arranged in said interior volume in a fixed manner relative to the case and engages with the crystal outside its periphery fastened by said fastening device, by contact with the lower surface of the crystal, particularly in a central zone of the crystal.

Description

[0001] Arrangement for fixing a glass of a timepiece

[0002] The present invention relates to an arrangement for fixing a crystal of a timepiece, as well as to a timepiece as such, particularly an extra-flat timepiece. The invention also relates to a method for fixing a crystal of a timepiece, belonging to a more general method of manufacturing a timepiece.

[0003] To create a thin timepiece, it is important to take into account the fact that a crystal is likely to deform under external pressure. Indeed, reducing the thickness of a timepiece can be based on reducing the thickness of the crystal and / or bringing it closer to the movement and / or hands. As a result, the effects of a deformation of the crystal become problematic, since it must be prevented from coming into contact with the movement or hands, so as not to disrupt the running of the timepiece or even damage the movement. In addition, if the crystal becomes more fragile, care must also be taken not to break it in the event of deformation.

[0004] Document CH706978 describes a solution consisting of using a surface of the frame of a watch movement to form a stop that reduces the travel of the crystal in the event of deformation, to prevent it from coming into contact with a hand. This solution is used in extreme cases of severe deformation of the crystal. In the normal configuration of the timepiece, such a stop has no effect. This solution therefore makes it possible to avoid certain extreme problems, but remains insufficient. For example, the crystal remains free to undergo slight deformations, up to the point of coming into contact or not with the stop, for example micro-vibrations, which requires the use of a sufficiently strong crystal, in particular of suitable thickness. A general object of the present invention is to propose a solution for fixing a crystal to a case of a timepiece, particularly suitable for a thin timepiece.

[0005] For this purpose, the invention is defined by the claims.

[0006] In particular, the invention is based on an arrangement for fixing a crystal of a timepiece comprising a case, comprising a device for fixing the crystal to the case at the periphery of the crystal, characterized in that it comprises a device for connecting the crystal comprising at least one support stud cooperating with the crystal outside its periphery or outside the watch case, in particular in a central zone of the crystal.

[0007] The at least one stud may comprise a lower portion for mounting on the timepiece, and an upper portion in contact with the lower surface of the glass.

[0008] The arrangement may comprise several support pads, in particular between 1 and 10, and several support pads in contact with the ice at its central zone.

[0009] The arrangement for fixing a crystal may comprise several support studs distributed in a substantially homogeneous manner over a central area of ​​the crystal and / or near components of the movement intended for positioning at a very short distance from the crystal, such as a wheel or a hand.

[0010] The invention also relates to a timepiece, comprising a crystal and a case, characterized in that it comprises an arrangement for fixing the crystal to the case as defined previously. The at least one support stud can be fixed to a bridge of the movement of the timepiece.

[0011] The at least one support stud may be fixed to a head of a screw of a bridge of the movement of the timepiece. The support stud may comprise an annular shape capable of cooperating with a protrusion of the screw of the bridge of the movement of the timepiece.

[0012] The at least one support block can be fixed in a height-adjustable manner so as to ensure its contact with the ice.

[0013] The glass may have a thickness less than or equal to 0.4 mm, or even less than or equal to 0.35 mm, in particular between 0.2 and 0.4 mm, and / or the glass may have a diameter greater than or equal to 30 mm, or even greater than or equal to 30 mm, and / or a diameter less than or equal to 45 mm, or even less than or equal to 40 mm.

[0014] The timepiece may have a total thickness less than or equal to 2 mm, or even less than or equal to 1.9 mm, or even less than or equal to 1.85 mm.

[0015] The invention also relates to a method for fixing a glass of a timepiece, characterized in that it comprises the following steps:

[0016] - Fixing the glass at its edge on a case of the timepiece;

[0017] - Connection of the ice by at least one support stud coming into contact, optionally in fixing, with the ice on an area outside its periphery or outside the box, in particular in the central part of the ice. Other advantages and characteristics will emerge more clearly from the following description of a particular embodiment of the invention given by way of non-limiting example and represented in the appended drawings, in which:

[0018] Figure 1 represents a top view of a timepiece according to one embodiment of the invention.

[0019] Figure 2 represents a perpendicular sectional view at the level of a bridge of the timepiece according to the embodiment of the invention.

[0020] Figure 3 represents a perpendicular sectional view at the level of a support stud of the timepiece according to the embodiment of the invention.

[0021] Figure 4 represents a perspective view of a screw of the timepiece according to the embodiment of the invention.

[0022] Figure 5 represents a perspective view of a support stud of the timepiece according to the embodiment of the invention.

[0023] Figure 6 represents a perspective view of the assembly of a support stud on the screw of the timepiece according to the embodiment of the invention.

[0024] To simplify the description, we will conventionally use the terms "horizontal direction" for any direction parallel to the crystal of the timepiece. We will use the "perpendicular direction" for any direction perpendicular to the crystal of the timepiece. We will use the adjectives "upper" and "lower" to designate elements or surfaces with reference to the perpendicular direction, respectively positioned on the side of the gaze of the user of the timepiece and on the opposite side, for example on the wrist of a wearer in the case of a wristwatch.

[0025] Figure 1 represents a top view of a timepiece 1 according to one embodiment of the invention. This timepiece 1 is a wristwatch comprising a case 2, which comprises horns 3 provided for the attachment of bracelet strands, not shown.

[0026] The case 2 comprises a back or plate and a case middle, and a bezel 4 arranged on the case middle around the perimeter of the case 2. Alternatively, any other architecture of the case 2 is possible.

[0027] The timepiece 1 further comprises a crystal 10, barely visible in FIG. 1, which is first fixed in a conventional manner by a fixing device at its periphery, at the level of the case 2, and more particularly of the caseband and / or the bezel 4. This first fixing means may be gluing, or a mechanical means. The bezel is fixed in a traditional manner to the caseband, for example by screws, such as octagonal head screws, from the back of the watch. Thus, this rather traditional fixing device involves areas of the periphery of the crystal and corresponding areas on the watch case.

[0028] The timepiece 1 further comprises a watch movement, fixed in the upper part by bridges 5. It also comprises at least one dial 6 and at least one hand 7. The case 2 and the crystal delimit in whole or in part an interior volume of the timepiece, in which the watch movement is arranged.

[0029] Figure 2 shows a cross-sectional view through a perpendicular plane of the timepiece 1. According to this embodiment, the timepiece is extra-flat. Advantageously, the total thickness of the timepiece is less than or equal to 2 mm, or even less than or equal to 1.9 mm, or even less than or equal to 1.85 mm. This thickness may be greater than or equal to 1.7 mm.

[0030] It follows firstly that the glass 10 is chosen to be very thin, for example of the order of 0.3 mm. Advantageously, the thickness of the glass is less than or equal to 0.4 mm, or even less than or equal to 0.35 mm. It is also advantageously greater than or equal to 0.2 mm, or even greater than or equal to 0.25 mm. This thickness is preferably constant. Alternatively, it may be variable, in which case the values ​​mentioned above are the minimum or average values. The glass 10 also has a diameter greater than or equal to 30 mm, or even greater than or equal to 35 mm. The glass 10 also has a diameter less than or equal to 45 mm, or even less than or equal to 40 mm. Its outline may be circular. Alternatively, it may have any other shape, square, rectangular, ellipsoidal, etc. In all cases, its area may remain within the same values ​​as those resulting from the aforementioned diameter range.The crystal 10 can be made of any known material, for example sapphire.

[0031] In addition, the crystal 10 comes close to the movement, to minimize the overall thickness of the timepiece. It thus appears that the space 1 1 between the lower surface of the crystal 10 and the upper surface of a bridge 5 of the movement or of a hand 7, as shown schematically in FIG. 2, can be very small, for example less than or equal to 0.1 mm.

[0032] It appears that with the dimensioning defined above, the crystal 10 would be likely to deform in a significant manner if it were only fixed by the aforementioned fixing device, and that this deformation would be sufficient for it to come into contact with the movement, in particular a bridge, which could induce pinching of the gear train, and / or a hand 7. For this reason, depending on the embodiment, the crystal 10 is further held by one or more support studs 20, which come into contact with the lower surface of the crystal 10. In other words, the crystal 10 is supported on the support stud(s) 20. Such a crystal, due to its reduced thickness, is also likely to undergo all kinds of vibrations and deformations, even of very low amplitude, without necessarily coming into contact with the movement or a hand. These deformations are likely to induce wear and embrittlement of the crystal.The support stud(s) 20 make it possible to eliminate or reduce this phenomenon.

[0033] According to one embodiment, a support stud 20 is advantageously arranged on an upper bridge 5 of the movement, or even on a plate. It thus extends vertically from such a bridge 5, until it comes into contact with the lower surface of the crystal 10. Alternatively, it can be fixed to any other surface of the movement or of the timepiece. Preferably, it is fixed outside an axis of the movement, so as not to risk disturbing the rotation of such an axis. It therefore advantageously extends from a fixed surface, without connection with an axis of rotation of the movement. It is therefore distinct from an axis of the watch movement, or from a moving element of the watch movement. Such a support stud 20 is thus mounted in a fixed manner relative to the timepiece, more precisely relative to the watch case 2, unlike components of the watch movement, such as gear trains and pivot axes, and unlike elements likely to deform.

[0034] The function of a support stud 20 is to supplement the crystal fixing device provided at its periphery, by forming all or part of a connecting device, positioned at an area outside the periphery of the crystal or outside the watch case, that is to say outside the areas of the periphery of the crystal and the watch case on which the crystal fixing device is implemented. The support stud therefore adds elements for holding the crystal, distinct from and complementary to the traditional fixing device.

[0035] A support stud is thus preferably arranged in a central zone of the crystal 10. Such a central zone can be defined as a disk of radius R / 2 or 3R / 4 of the crystal, centered on the center of the crystal, where R is the radius of the crystal. If the crystal does not have a circular contour shape, the same principle can be applied by considering the disk of minimum radius in which the crystal is inscribed. A support stud is therefore positioned in the interior volume of the timepiece, comprises a lower part fixed to the timepiece, such as a plate or a bridge of the movement, and an upper part in contact with the lower surface of the crystal.

[0036] This connecting device comprising one or more support studs has the function of preventing the deformation of the crystal 10, at least at the level of a support stud 20. By this construction, the fixing of a crystal, obtained by the combination of the fixing device and the connecting device, is such that it does not deform, or very little, so that it does not come into contact with the movement or a hand. More generally, it does not undergo any or very little deformation.

[0037] According to the embodiment shown in Figure 1, two support studs 20 are used. Advantageously, the connecting device comprises several support studs 20, for example 2, 3, 4, 5, or 6, or more generally any number between 1 and 10. Furthermore, according to one embodiment, these support studs are advantageously distributed in a fairly homogeneous manner, and at least partly outside the periphery of the crystal. Preferably, they are positioned on a central part of the timepiece. Thus, several support studs 20 can be advantageously positioned at the level of the disc of radius R / 2, or even radius 3R / 4, of the crystal 10, where R is the radius of the crystal. In other words, the central zone is delimited by a circle of radius 3R / 4, or even R / 2, where R is the radius of the circle in which the crystal (10) is inscribed.Alternatively or additionally, the support stud(s) 20 may be positioned near the bridge 5 and / or needle 7 surfaces closest to the crystal 10. The support studs 20 may be identical or different.

[0038] According to the preferred embodiment, represented by FIG. 3, a support stud 20 is fixed on a screw 11 of the movement, more precisely on a head 12 of a screw 11 fixed on a bridge 5 of the movement. For this, the head 12 of the screw 11 is arranged to comprise a first cooperation device, for example a central axis, capable of cooperating with a support stud 20.

[0039] Figures 4 to 6 illustrate for this purpose an example of assembly of a screw 11 of a bridge of the movement with a support stud 20. Figure 4 represents a screw 11. This screw 11 comprises a protruding cylindrical portion 12 at its head, which extends around a vertical axis coincident with the axis of the screw 11. Notches 13 are provided on the periphery of the screw head, to allow the insertion of a tool and the possible actuation of the screw 11. Figure 5 represents a support stud 20, which has an annular shape, of dimensions corresponding to the screw 11, to be able to cooperate with its head, as represented by Figure 6, and to protrude in height above the head, exactly filling the space between the screw 11 and the glass 10 to come into contact with the glass 10, as represented by Figure 3.

[0040] In such an embodiment, it is possible to provide support blocks 20 of different heights, possibly custom-made, to perfectly fill the height between a bridge 5 and the ice 10. According to such an embodiment, a support block 20 thus has a height calculated to correspond exactly to the distance between the movement and the ice, in particular in cases where the construction clearances are small or can be neglected.

[0041] A support pad 20 is advantageously sufficiently rigid to prevent deformation of the ice, while being sufficiently flexible not to form a hard point on the ice, which would risk damaging it. For this, the support pad 20 is preferably made of a rigid rubber or polymer material, for example a transparent silicone.

[0042] According to an alternative embodiment not shown, the positioning of a support stud 20 can be adjustable in height. For this, it can comprise a lower mounting part screwed onto the movement, for example on a bridge 5, so that its height can vary depending on the screwing. Alternatively, any other mechanical height adjustment solution is possible. Such an embodiment makes it possible to compensate for any play and / or to guarantee contact with the crystal in all cases, with any desired pressure, even when the construction play is not negligible.

[0043] As a note, in all cases, the lower surface of the crystal 10 may comprise a coating at the contact with a support stud 20. Such a coating may have a first function of reinforcing the crystal at the contact, and a second aesthetic function of masking the contact stud for a user of the timepiece.

[0044] The invention therefore relates to an arrangement for fixing a crystal 10 of a timepiece, as described above. It also relates to a timepiece as such. As described above, it is particularly suitable for a timepiece of very low thickness, in particular a wristwatch.

[0045] As a further remark, the arrangement has been described as comprising at least one support pad which comes into contact with the glass, to maintain its position at a constant height, to prevent its deformation in the event of stress exerted on its upper surface. As is implicit in the preceding description, such contact is formed with the glass in its rest position, i.e. undeformed. In other words, the contact of the support pad with the glass is thus a permanent contact. Alternatively, the support pad 20 may be fixed to the glass, for example by gluing or mechanical means, and thus form a second device for fixing the glass.

[0046] In all cases, a support stud therefore behaves differently from a stop as described in document CH706978, which has no effect on the glass apart from its most significant deformations. The support stud of the invention acts as an element for holding the glass in an initial, undeformed position, and acts permanently on this glass to maintain it in this initial position. It therefore contributes to the overall fixing of the glass to the timepiece.

[0047] The invention also relates to a method for fixing a glass to a timepiece, characterized in that it comprises the following steps: Fixing the glass 10 at its periphery to a case 2 of the timepiece;

[0048] Connection of the glass 10 by at least one support pad 20 coming into contact, optionally in fixing, with the glass 10 on an area outside its periphery fixed in the previous step, in particular in the central part.

[0049] Advantageously, the method comprises a step of adjusting the height of the at least one support stud 20 to guarantee its contact with the glass 10.

[0050] This process of fixing a glass is part of a more general process of assembling a timepiece, and of manufacturing a timepiece.

Claims

DEMANDS 1. A timepiece comprising a case (2) and a crystal (10) delimiting an internal volume in which a timepiece movement is disposed, the timepiece comprising a device for fixing the crystal (10) to the case (2) at the level of the periphery of the crystal (10), characterized in that the timepiece further comprises a device for connecting the crystal (10) comprising at least one support stud (20) disposed in said internal volume in a fixed manner relative to the case (2), and cooperating with the crystal outside its periphery fixed by said fixing device, by contact with the lower surface of the crystal (10), in particular in a central area of ​​the crystal (10).

2. A watch part according to the preceding claim, characterized in that at least one support stud (20) is in permanent contact with the lower surface of the crystal (10) or is fixed to the lower surface of the crystal (10), to ensure its retention.

3. A timepiece according to any one of the preceding claims, characterized in that at least one support stud (20) comprises a lower mounting part on the timepiece, for its fixed mounting relative to the case (2).

4. A timepiece according to any one of the preceding claims, characterized in that it comprises several support pads (20), in particular between 1 and 10, and several support pads (20) in contact with the crystal (10) at the level of its central area delimited by a circle of radius 3R / 4, or even R / 2, where R is the radius of the circle in which the crystal (10) is inscribed.

5. A timepiece according to the preceding claim, characterized in that it comprises several support pads (20) distributed in a substantially homogeneous manner on said central area of ​​the crystal (10) and / or near movement components intended for positioning at a very short distance from the crystal (10), such as a wheel or a hand (7).

6. Timepiece (1) according to any one of the preceding claims, characterized in that at least one support stud (20) is fixed on a bridge (5) of the time movement or on a plate of the timepiece.

7. Timepiece (1) according to the preceding claim, characterized in that at least one support stud (20) is fixed on a head of a screw (11) of a bridge (5) of the movement of the timepiece.

8. Timepiece (1) according to the preceding claim, characterized in that at least one support stud (20) comprises an annular shape suitable for cooperating with a protrusion (12) of the screw (11) of the bridge (5) of the movement of the timepiece.

9. Timepiece (1) according to any one of the preceding claims, characterized in that at least one support stud (20) is fixed in a height-adjustable manner so as to be able to guarantee its contact with the glass (10).

10. A timepiece (1) according to any one of the preceding claims, characterized in that the crystal (10) comprises a thickness less than or equal to 0.4 mm, or even less than or equal to 0.35 mm, in particular between 0.2 and 0.4 mm, and / or in that the crystal (10) comprises a diameter greater than or equal to 30 mm, or greater than or equal to 30 mm, and / or a diameter less than or equal to 45 mm, or less than or equal to 40 mm. 1 1. Timepiece (1 ) according to one of the preceding claims, characterized in that it comprises a total thickness less than or equal to 2 mm, or less than or equal to 1.9 mm, or less than or equal to 1.85 mm.

12. A watch part (1) according to any one of the preceding claims, characterized in that at least one support stud (20) is distinct from an axis of the watch movement or from a moving element of the watch movement.

13. A method for fixing a crystal (10) of a timepiece, characterized in that it comprises the following steps: - Fixing the glass (10) at its perimeter on a case (2) of the timepiece; - Connection of the ice (10) by at least one support block (20) coming into contact, optionally by fixing, with the ice (10) on an area outside its perimeter fixed in the previous step, in particular in the central part of the ice (10).

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