EP1035453B1 - Dial comprising brilliants, applied ornaments or other attached elements and process for fixing such elements onto such a dial - Google Patents

Description

The invention relates to a dial comprising brilliants, appliques or other added elements and more particularly a clock face comprising such decorative elements having a base surface plane. The invention also relates to a method of fixing decorative elements. reported on a dial.

We already know clock faces presenting on one of their faces of the decorative elements intended to form signs hours.

A first technique for manufacturing these dials is to fix decorative elements, usually cut stones, between two rings each presenting a seat, and driving the assembly thus formed into a drilling the dial. Such a technique is for example described in the document CH 260 123. This technique however has the drawback of having to make and handle many very small parts, which requires a skilled workforce and leads to cost prices high.

Another classic technique for fixing decorative elements with a flat base surface consists of gluing, using an adhesive liquid or semi-liquid, the decorative elements by their base surface in countersinks in the thickness of the dial in places predetermined. This technique although less expensive than the previous one has many drawbacks, however.

JP09119986 describes a method of crimping a luminescent element in a housing having a layer of adhesive material on its bottom.

Indeed, a first drawback is that the bonding of the elements decorative is difficult to achieve automatically due to the low dimensions of the decorative elements in question. As an indication, the brilliant commonly used to form time signs exhibit diameters of the order of 2 mm. Bonding operations for each element decorative, between one and twelve per dial depending on the case, must be made manually, which significantly increases manufacturing costs of these dials.

A second drawback is that it is difficult to dose precisely how much glue to deposit in each recess to achieve a satisfactory bonding, that is to say a bonding during which the amount of glue deposited is neither too large, which would risk to cause an overflow on the useful face of the dial when setting place of the decorative element, or insufficient, which could cause a separation during subsequent use.

This process is also particularly disadvantageous when such dials are mounted in one-piece watch cases made of plastic closed by a glass welded by ultrasound. Indeed, the Applicant has found that, during the operation of welding the ice to the box, the ultrasonic vibrations propagated into the glue fixing the decorative elements on the dial, and tended to crack and break the layer of glue and untimely detach said elements decorative of their seats.

The known methods therefore present general problems industrialization that should be eliminated.

The main object of the invention is therefore to provide a dial, such as a clock face, including decorative elements which are either simple and inexpensive to manufacture.

The invention also aims to provide a method of fixing decorative elements on a dial, this process allowing a secure fixing decorative elements on the dial while being easily industrializable and simple to implement.

To this end, the invention relates to a dial, in particular for a coin timepiece, comprising a plate having at least one housing in which is attached a decorative element or the like, characterized in that the housing comprises a bottom formed by an adhesive tape, the adhesive face of said ribbon being in contact with said decorative element.

Thanks to these characteristics, ultrasonic vibrations can be damped by the intrinsic flexibility characteristics of the ribbon and thus eliminate the problems of rupture of the adhesive layer retaining the elements decorative on the dial.

• se munir d'un cadran ou d'une plaque dans laquelle seront découpés une pluralité de cadrans;
• pratiquer dans ledit cadran ou ladite plaque, aux endroits destinés à recevoir lesdits éléments décoratifs, des ouvertures traversant l'épaisseur du cadran ou de ladite plaque;
• appliquer un ruban adhésif sur la face inférieure du cadran ou de ladite plaque, de sorte que la face du ruban adhésif comportant la matière adhésive soit dirigée vers lesdites ouvertures,
• poser lesdits éléments décoratifs dans les ouvertures pour qu'ils viennent se coller par une de leurs faces sur la face adhésive du ruban.

The subject of the invention is also a method of fixing decorative elements to a dial, characterized in that it comprises the steps consisting in:

• have a dial or a plate from which a plurality of dials will be cut;
• making in said dial or said plate, at the places intended to receive said decorative elements, openings crossing the thickness of the dial or of said plate;
• applying an adhesive tape to the underside of the dial or of said plate, so that the face of the adhesive tape comprising the adhesive material is directed towards said openings,
• place said decorative elements in the openings so that they come to stick by one of their faces on the adhesive face of the tape.

Thanks to these characteristics, all the problems linked to the machining of holes and glue dosage of the prior art are eliminated, and one can fix the decorative elements easily by simple application of these last on the bottom, formed by the glued side of the adhesive tape, dial openings provided for this purpose.

• la figure 1 est une vue en plan d'un cadran selon l'invention;
• la figure 2 est une coupe selon la ligne I-I de la figure 1;
• la figure 3 est une vue en plan partielle d'une variante de réalisation du cadran de l'invention;
• la figure 4 est une vue en plan partielle d'une autre variante de réalisation du cadran de l'invention;
• la figure 5 est une coupe selon la ligne IV-IV de la figure 4;
• la figure 6 est vue en perspective d'une plaque dans laquelle une pluralité de cadrans selon l'invention sont étampés, la plaque étant représentée avant l'opération de collage du ruban adhésif, et
• la figure 7 et une vue en perspective d'un ruban adhésif étampé selon l'invention avant l'opération de collage sur la plaque comprenant les cadrans.

Other advantages and characteristics of the invention will become apparent in the light of the following description of a preferred embodiment, presented by way of nonlimiting example with reference to the appended drawings in which:

• Figure 1 is a plan view of a dial according to the invention;
• Figure 2 is a section along line II of Figure 1;
• Figure 3 is a partial plan view of an alternative embodiment of the dial of the invention;
• Figure 4 is a partial plan view of another alternative embodiment of the dial of the invention;
• Figure 5 is a section along the line IV-IV of Figure 4;
• FIG. 6 is a perspective view of a plate in which a plurality of dials according to the invention are stamped, the plate being shown before the operation of gluing the adhesive tape, and
• Figure 7 and a perspective view of a stamped adhesive tape according to the invention before the bonding operation on the plate comprising the dials.

Referring first to Figure 1, the reference 1 denotes a dial formed by a disc of metal or rigid plastic material comprising a visible front face 2 and an opposite face 4 called rear face. This disc is typically obtained by stamping a plate, using a die and an appropriately shaped punch. Dial 1 according to the invention includes circular housings 6 on the bottom of which are fixed decorative elements 8 appearing on the front face 2. The dial 1 also conventionally includes a hole 10 provided for the passage needles (not shown).

In the following description, the term “decorative element” means a gloss, a wall lamp or any other decorative element that can be attached to a dial and in particular a clock face. Although in the example illustrated in FIG. 1, the decorative elements 8 have been provided respectively for twelve o'clock, three o'clock, six o'clock and nine o'clock positions to constitute time signs, it stands to reason that these decorative elements could be arranged in any other place on the dial insofar as they do not interfere not with the central hole 10 provided for the passage of the needles.

As can be seen from FIG. 2, the housings 6 are formed by openings 12 passing right through the thickness of the plate forming the dial 1, these openings 12 each being closed by a bottom 14 formed from a portion of adhesive tape 16 glued to the rear face 4 of the dial 1. The openings 12 have dimensions substantially greater than those of the decorative elements 8, which makes it easier to install the decorative elements in the housings 6. The adhesive side of the tape 16 forming the bottom 14 is in close contact with the base 18 of the element decorative 8, which thus ensures the fixing of this element 8, on the dial 1.

Note in this regard that it is advantageous to choose elements decorative 8 having a substantially flat base 18 and this for increase the surface of the element 8 coming into contact with the material adhesive tape 16. It will further be noted that it is advantageous to choose a adhesive tape 16 having a thickness as small as possible so as not to increase the total thickness of dial 1 taking into account the space generally low available for this one in a watch box and the general trend towards making watches of relatively low thickness.

To fix ideas, the openings typically have a diameter of about 2 mm, the dial has a thickness of about 0.4 mm and the adhesive tape has a thickness of the order of 0.05 mm.

The adhesive tape 10 is for example a tape known as Scotch 850 or Scotch 396 trade names sold by the company 3M or under the trade designation Tesa film 4129 sold by the TESA company.

According to a preferred embodiment, the adhesive tape 16 used is common to all of the housings 6 and for this purpose has a width sufficient to form a bottom 14 simultaneously for all the openings 12 of the dial. To this end, the ribbon 16 has a width allowing cover at least the whole of the rear face 4 of the dial 1.

According to a variant not shown, the adhesive tape 16 can have adhesive material on both sides and thus ensure also keeping the dial 1 in place in the watch case.

In Figures 3 to 5 there are shown two alternative embodiments of a dial according to the invention. Elements identical to those already described in connection with Figures 1 and 2 are designated by the same reference numerals.

In the example of FIG. 3, the decorative element 8 is presented under the shape of a rectangular gloss housed in a housing 6 of shape corresponding. The gloss 8 is fixed to the bottom 14 by means of a ribbon adhesive 16 glued to the back of the dial.

In the example shown in Figures 4 and 5, the decorative element 8 is in the form of a stick with a T-shaped cross section, the upper part 8a extends beyond the periphery of the opening 12 in which is housed the lower part 8b. This lower part 8b comprises a flat bottom 18 which comes into close contact with the adhesive face of the tape adhesive 16 bonded to the rear face 4 of the dial 1. The stick 8 is by example made of silver plastic material of ceramic or the like and advantageously forms time signs having an original appearance. This embodiment has the advantage of being able to hide the space free located between the decorative element 8 and the edge of the opening 12 which is normally visible in the case of dials with elements decorative such as brilliants or the like.

We will now describe the method of fixing decorative elements. on a dial according to the invention in conjunction with FIGS. 6 and 7.

The plate P (Figure 6) in which will be stamped a plurality of dials is for example cut from a coil (not shown) and supplied to a conventional stamping station also not shown.

During a first step, we practice by stamping in the plate P, at the places intended to receive decorative elements 8, openings 12 passing right through the thickness of the plate (Figure 6). Plate P comprises a determined number of dials, typically one half a dozen.

In this particular case, the punch and the die are provided for simultaneously form a hole 10 in the stamping of the openings 12 substantially in the center of each dial 1 to allow passage subsequent axes on which the needles of the workpiece will be fixed of watchmaking that the dials are intended to equip. There are also plans indexing and drive holes 20 for ensuring precise positioning of the plate for subsequent operations as well as perforations for positioning the dial in the watch case. These perforations are typically made at six o'clock on the edge of the dial.

Note also that the dials 2 are cut from the plate P, so that each of these substrates is connected to the rest of the plate by four bridges of material 22. The number and dimensions of the bridges of material 22 vary depending on the shape and the material from which the dial. Typically, the bridges are such that they later allow a easy extraction of dials from the band, for example by a simple pressure on these.

Alternatively, one could also consider using a technique called re-striping stamped dials, i.e. replace the dials 1 in the plate P at the places where they were cut out, the dials 1 being held in the plate P by microwelds which spontaneously create when the stamped part is driven into the place of the P band from which it comes.

It goes without saying that other means of cutting could be considered. We will mention in this regard in particular the cutting by laser beam and high pressure water jet cutting.

During a parallel step, the adhesive tape 16 is prepared which will subsequently be glued to the rear face 4 of the dials 1. To do this, we cut a section of ribbon 16 from a roll which feeds a station stamping. The length and width of the ribbon section 16 correspond to those on plate P. We cut in the stamping station shapes corresponding to those of the dials 2 cut from the plate P with the exception of the openings 12. These shapes are of course cut out in layout and number corresponding to what has been achieved on the plate P. The various elements of the ribbon 16 have been designated in FIG. 7 corresponding to those of plate P by the same reference numeral with the letter r.

In a next step, apply to the back of the plate P the adhesive tape 16, so that the face of this tape 16 comprising the adhesive material is directed towards the openings 12. The application of the tape 16 can of course be carried out so automatic.

In the last step of the process, we just put the elements decorative 8 in the bottom 14 of the openings 12 and we apply a light pressure so that they come into close contact by one of their faces with the adhesive side of the tape 16 and thus ensure their fixing by gluing in the housings 6 of the dials 2. The fitting of the decorative elements 8 is preference performed automatically.

It goes without saying that the steps which have just been described apply to the treatment of unitary dials.

The essential advantage of the process described above resides in the fact that it is particularly simple, so it can be easily automated. Through elsewhere, the tests carried out by the applicant have led to results confirming the reliability of the attachment of the decorative elements 8 to the dial 2. The rate of waste of the dials thus produced could be reduced so important compared to the fixing techniques of the prior art.

Claims (10)

1. Dial, in particular for a timepiece, including a rigid plate having at least one housing (6) in which a decorative element (8) or suchlike is secured, characterised in that the housing (6) which is made in said rigid plate, includes a bottom (14) formed of an adhesive strip (16), the adhesive face of said strip (16) being in contact with said decorative element (8) and wherein said rigid plate forms said dial.
2. Dial according to claim 1, characterised in that the housing (6) is formed by an opening (12) made right through the thickness of the dial (1), the opening being closed by the adhesive strip (16) glued to the back face (4) of the dial (1).
3. Dial according to claim 1 or 2, characterised in that the decorative element or elements (8) have a bottom at least a part (18) of which is substantially flat.
4. Dial according to any of claims 1 to 3, characterised in that the adhesive strip (16) has a sufficient width to receive the entirety of the back face (4) of the dial (1).
5. Dial according to any of claims 1 to 4, characterised in that said openings (12) have substantially larger dimensions that those of the decorative elements (8).
6. Dial according to any of claims 1 to 5, characterised in that the adhesive strip (16) includes adhesive material on its two faces.
7. Dial according to any of claims 1 to 6, characterised in that the thickness of the adhesive strip (16) is of the order of 50 micrometers.
8. Method for securing decorative elements on a dial, characterised in that it includes the steps of:

   providing a rigid dial (1) or a plate (P) in which a plurality of dials (1) will be cut;

   making in said dial (1) or said plate (P), at the locations intended to receive said decorative elements (8), openings (12) passing through the thickness of said dial (1) or said plate (P);

   applying an adhesive strip (16) onto the bottom face (4) of said dial (1) or said plate (P), so that the face of the adhesive strip (16) including the adhesive material is directed towards said openings (12);

   placing said decorative elements (8) in the openings (12) so that they are glued via one of their faces to the adhesive face of the strip (16).
9. Securing method according to claim 8, characterised in that the openings (12) are formed by stamping.
10. Securing method according to claim 8 or 9, characterised in that, prior to the adhesive strip application step, it includes a step for stamping the adhesive strip to give it a shape corresponding to that of the dial with the exception of said openings.

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