CH713156B1 - Dial for timepiece. - Google Patents

Abstract

The invention relates to a dial (1) for a timepiece, comprising: - a first substrate (3) comprising a first surface (19) intended to be located opposite a watch glass and a second surface (20) opposite to said first surface (19), said first substrate (3) further comprising at least one window (5) serving as an index; - at least a second substrate (7) fixed to said first substrate (3) facing said second surface (20) and associated with a light or luminescent source (11), said second substrate (7) comprising an area facing said at least one window (5); - a tinted layer (21) located on at least part of said first surface (19) of said first substrate (3). According to the invention, said layer (21) comprises carbon nanotubes. The invention also includes a method of manufacturing a dial.

Description

Technical area

The present invention relates to the field of watchmaking. It relates more particularly to a watch dial as well as to its manufacturing process.

State of the art

The Panerai house is well known for its multi-level black dials, the indexes of which are formed by openings in a top plate. These openings reveal a lower plate provided with a luminescent layer. This arrangement provides a clearly readable dial, not only during the day, but also at night.

[0003] The readability of the dial depends on the contrast between the color of the upper plate and that of the lower plate, particularly under strong direct light. Typically, a black color layer is applied to the top plate to provide this contrast.

[0004] However, the varnishes and paints commonly used for this purpose reflect too much incident light to provide sufficient readability in the event of strong direct light. This drawback occurs even when the black color is formed from amorphous vapor deposited carbon, as described in CH705576.

[0005] The aim of the invention is therefore to provide a dial for a timepiece, in which the aforementioned defects are at least partially overcome. The invention also relates to a method of manufacturing such a dial.

Disclosure of the invention

[0006] More specifically, the invention relates to a dial for a timepiece. This dial is multi-level, and for this purpose comprises a first substrate comprising a first surface intended to be located opposite a watch glass, as well as a second surface on the side opposite to said first surface. The first substrate further comprises at least one window, constituted for example by an opening in the case of an opaque material and an optical passage in the case of a translucent material, this window serving as an index. The dial further comprises at least one second substrate attached to said first substrate facing said second surface and which is associated with a light source, said second substrate comprising an area facing said at least one window. Therefore, part of the second substrate, or a coating located thereon, is visible through the window (s).

[0007] The upper surface of the first substrate comprises a tinted layer on at least part of its surface, which, according to the invention, comprises carbon nanotubes. In the case of a first translucent substrate, the windows can be formed by selective deposition of this layer.

The use of carbon nanotubes in the layer gives the first substrate a particularly deep blackness, which improves the contrast with the surface of said zone of the second substrate visible through the openings. This contrast is sufficient even to provide adequate contrast when the dial is subjected to direct strong illumination, and minimizes light reflections from its surface.

[0009] In one variant, said layer comprises a varnish comprising at least 0.1% by mass, preferably at least 1.0% by mass, of carbon nanotubes. The dial can thus be produced using conventional varnishing equipment, without having to subject the dial to a heat source.

[0010] In another variant, said layer comprises carbon nanotubes deposited directly on said surface or directly on an additional substrate attached to said surface. A particularly dark color, which has a light absorption coefficient which approaches 100%, is therefore obtained. To maximize this effect, at least 50% of the carbon nanotubes can extend substantially perpendicular to the plane of said first substrate.

Advantageously, the light source can be a luminescent coating deposited on said second substrate facing said opening, for example in a hollow formed in the surface of this substrate for this purpose, or directly on the flat surface of the latter. The second substrate can even be made from a luminescent material.

[0012] Alternatively, the light source comprises an electric light source, for example a thin-film LED placed on the surface of the second substrate, a conventional or thin-film LED placed between the two substrates and the light of which is reflected by a paint, surface treatment or coating, fluorescent tint, the native surface of the substrate, or the like, visible through the openings, or the like. Alternatively, the light source can be passive, such as an element comprising a photoluminescent material, for example a tritium element.

[0013] The invention also relates to a method of manufacturing a dial for a timepiece, comprising the following steps, which do not necessarily have to take place in the order indicated; any feasible sequence of steps is possible: <tb> - <SEP> provide a first substrate comprising a first surface intended to be located opposite a watch glass and a second surface opposite said first surface, at least one region of said first substrate being intended to form at least one window serving as an index. The first substrate can be obtained by additive or subtractive manufacturing processes, or a combination of the two; if it is made additively, said at least one window can be formed as an opening directly during the manufacture of the substrate; - Provide a first substrate comprising a first surface intended to be located opposite a watch glass and a second surface opposite to said first surface, at least one region of said first substrate being intended to form at least one window serving index. The first substrate can be obtained by additive or subtractive manufacturing processes, or a combination of the two; if it is made additively, said at least one window can be formed as an opening directly during the manufacture of the substrate; <tb> - <SEP> perforating, where appropriate, said substrate in order to form at least one opening constituting said window. This step is not carried out in the case of a substrate having openings formed entirely during additive manufacturing, or in the case of a non-perforated translucent substrate; <tb> - <SEP> applying to at least a part of said first surface of the first substrate a layer comprising carbon nanotubes; it should be noted that this step can be carried out before that of the perforation of the substrate, if necessary, and in the case of a translucent substrate, the windows can be formed by selective application of said layer during this step; <tb> - <SEP> provide a second substrate associated with a light source, said second substrate comprising a zone intended to be located opposite said at least one window; <tb> - <SEP> fixing said second substrate to the first substrate facing the second surface, so that said area is facing said at least one opening. Again, this step can take place before the step of applying said layer.

In doing so, a dial is obtained in which the use of carbon nanotubes in said layer gives a particularly deep blackness to the first substrate, which improves the contrast with the surface of said zone of the second substrate visible through the openings . This contrast is sufficient even to provide adequate contrast when the dial is subjected to direct strong illumination, and minimizes light reflections from its surface.

[0015] In a variant, said layer is applied in the form of a varnish comprising at least 0.1% by mass, preferably at least 1% by mass, of carbon nanotubes, which is compatible with current varnishing equipment, and not requires no heating of the substrate.

Advantageously, the method further comprises a step of burning at least part of said layer in order to cause combustion of at least part of said varnish. In doing so, part of the varnish is converted to amorphous carbon, which reduces the shine of the surface and makes it even more matt.

[0017] In an alternative variant, said layer is applied by a deposition process, for example a PVD, CVD or similar deposition.

Advantageously, at least 20% of the carbon nanotubes extend substantially perpendicular to the plane of said first substrate, which provides a particularly deep darkness to the first substrate.

[0019] In a variant, the light source is a luminescent coating deposited on said second substrate, for example in a hollow created for this purpose, or directly on a flat surface of the substrate.

[0020] Alternatively, the light source may comprise an electric light source, for example a thin-film LED placed on the surface of the second substrate, a conventional LED placed between the two substrates and the light of which is reflected by a paint, a surface treatment, a fluorescent tint or the like visible through the openings. Alternatively, the light source can be a tritium element, or an element comprising any other photoluminescent material.

Finally, the invention also relates to a dial as defined above obtained and / or obtainable by a method as described above, as well as a timepiece comprising such a dial.

Brief description of the drawings

Other details of the invention will emerge more clearly on reading the following description, made with reference to the accompanying drawings in which: <tb> - Fig. 1 <SEP> is a schematic sectional view and a schematic plan view of a dial according to the invention; <tb> - Fig. 2 <SEP> is a schematic sectional view of part of a dial according to another variant of the invention; <tb> - Fig. 3 <SEP> is a schematic sectional view of part of a dial according to yet another variant of the invention; <tb> - Fig. 3a <SEP> is a schematic sectional view of part of a dial according to yet another variant of the invention; and <tb> - Fig. 4 <SEP> is a representation of a method for manufacturing a dial according to the invention, illustrating some of the components concerned at each step.

Embodiments of the invention

Figure 1 schematically illustrates a dial 1 according to the invention, in plan and in section along line A-A. This dial 1 comprises a first substrate 3, forming an upper plate, which is perforated in predetermined regions in order to form windows 5 acting as an index. In the variant illustrated, these windows 5 are formed by openings in the first substrate 3. This substrate 3 comprises a first surface 19, intended to be facing a glass of a timepiece and therefore visible to a user. , and a second surface 20, opposite said first.

The first substrate 3 is superimposed on a second substrate 7, forming a lower plate, located opposite the second surface 20 of the first substrate 3. In the illustrated variant, the second substrate 7 is a disc having substantially the same diameter than the first substrate 3, but it is also possible for the second substrate to be divided into several parts, each being located under corresponding windows 5. The second substrate 7 can carry dial feet 9, if the construction of the part in which the dial 1 is intended to be integrated so requires.

This second substrate 7 is fixed below the first 3, for example by gluing, welding, clamping, or by means of pins, studs, screws, or the like.

[0026] Furthermore, the dial 1 may include, as generally known, openings 17 for the passage of the needle axes.

[0027] The second substrate 7 is associated with a light source. In the variant illustrated in FIG. 1, this light source is a layer 11 of a luminescent material which the surface of the second substrate 7 comprises. This layer is provided in recesses 13 formed in the upper surface of the second substrate 7. By „ luminescent “is meant (at least partially) photoluminescent, phosphorescent, fluorescent or the like. A varnish can be made luminescent, for example by adding luminescent particles.

Alternatively, the two substrates 3, 7 can be spaced apart from each other, and the light source can be on the upper surface of the second substrate 7, as illustrated schematically in Figure 2. In this variant, the second substrate 7 can of course include hollows 13 to receive the light source. Still alternatively, the entire surface of the second substrate 7 may be coated with a luminescent layer, or the second substrate 7 itself may be made of a material which is at least partially luminescent as such.

As an alternative to a luminescent layer, the light source 11 may for example be a thin-film LED, supplied with energy by a battery. The LED is located below window 5 and is therefore directly visible to the user.

In the variant of Figure 3, the light source is a conventional LED, arranged so that it emits light beams in the gap between the two substrates 3, 7. A conventional bulb is also possible. A light-colored zone 11a or one comprising a colored or fluorescent layer can be situated opposite the window 5. The LED can emit visible light, or ultraviolet light. It is also possible that the entire upper surface of the second substrate 7 is colored or coated with a tint, a surface treatment, a reflective coating (for example metallic) or a fluorescent layer in order to convert and / or diffuse the color. light emanating from the LED. Again alternatively, the LED can be a thin-film LED which is located on the lower surface of the first substrate 3 facing the second substrate 7, or else on the upper surface of the second substrate 7 facing the first 3. In the latter case , the lower surface of the first substrate 3 can be arranged to reflect the light emanating from the LED, for example by being polished, colored, or the like. A tritium element can also serve as a light source 11.

In the variant of Figure 3a, the first substrate 3 is formed of translucent or transparent material, such as glass, quartz, transparent polymer or the like, and the window 5 is formed as part of the substrate 3 which does not include a tinted layer 21 in predetermined regions and therefore allows light to pass. This solution can also be applied to any other embodiment as described above. Furthermore, the light source 11 is located outside the substrates 3, 7, and its light is reflected between the surfaces of the latter. This solution is suitable for use with any light source, for example a tritium element, an LED, a bulb, or the like.

According to the invention, all or part of the upper surface 19 of the first substrate 3 is provided with a layer 21 comprising carbon nanotubes, more particularly at least 0.1% by mass of such nanotubes, or preferably at least 1.0 % by mass.

In fact, certain arrangements of nanotubes can produce an extremely deep black color, with a very high absorption coefficient, up to about 99.955%. Therefore, even in the case of strong direct light, the amount of reflected light remains very low, and the contrast between the color of the first substrate 3 and the portions of the surface of the second substrate 7 visible through the windows 5, stay good.

This layer 21 can, for example, be a varnish comprising at least 0.1% by mass of carbon nanotubes, which remains compatible with coating equipment already in use. The greater the proportion of nanotubes, the darker the shade. For example,> 1%,> 10%,> 20%,> 30% ... (mass percentage) are also advantageous. The base of the varnish can be transparent or already black in color.

In order to make the varnish even darker, at least part of its surface can be burned, for example by means of a heat treatment such as a gas flame, in order to burn the varnish . This burning converts part of the varnish into amorphous carbon, which reduces surface chipping, and makes the surface matt black.

Alternatively, the layer 21 can be a carpet of carbon nanotubes deposited directly on the first substrate 3 or on an additional substrate which is subsequently secured to the first substrate 3. Such a carpet can for example comprise at least 50% by mass of carbon nanotubes, or even at least 60%, 70%, 80% or 90% by mass, the remainder being made up of other forms of carbon (particularly the amorphous form). Vacuum deposition processes, for example by high temperature carbon evaporation in a high pressure noble gas environment (which represents a form of PVD), laser ablation synthesis, or CVD synthesis, can be used. The carbon nanotubes can be single-walled or multi-walled, or a mixture of the two, and typically have a diameter of the order of a few nanometers.

If the carbon nanotubes extend mainly in a direction perpendicular to the plane of the dial, the light absorption effect is particularly pronounced, since the light enters the nanotubes and in the interstices between the nanotubes, of where it can hardly go out without being absorbed. In such a case, it is possible to provide a proportion of at least 20%, at least 30% or even 40% or more of the nanotubes which follow this direction. A thickness of the layer 21 of between 0.05 mm and 1 mm makes it possible to guarantee sufficient absorption of light, and to prevent the layer 21 from becoming too thick.

This mat can optionally be coated itself with a protective layer, such as a varnish, or a deposit of another material, in order to prevent the nanotubes detaching from the substrate and generate carbon dust. inside the room. This protective layer can also be burnt as described above.

The dial thus constructed therefore has an ultra-black appearance on the first substrate 3, which makes an excellent contrast with the parts of the second substrate 7 visible through the windows 5, even in the case of direct illumination. very strong.

FIG. 4 schematically illustrates a variant of a method for manufacturing a dial 1 according to the invention. Only a portion of the dial and its components is illustrated in these figures, as is the case for Figures 2 and 3.

In a step 101, a first substrate 3 is provided, which can be a plate made of metal, plastic, crystalline material (diamond, alumina, silicon, SiN, SiC, SiO or the like) or any other suitable material .

In step 102, the plate constituting the first substrate 3 is perforated, where appropriate, in order to form the openings 5 serving as windows 5 intended to form indexes. These openings 5 can be created by cutting, stamping, wet or dry etching, or any other suitable process. This step can be omitted if the first substrate 3 is created at least partially by additive manufacturing, and if the windows are formed as openings manufactured at the same time as the substrate 3. On the other hand, if the first substrate 3 is translucent and the windows are intended to be formed by selective deposition of the layer 21 in the following step, this step can also be omitted.

In step 103, the layer 21 comprising carbon nanotubes is applied to the upper surface 19 of the first substrate 3, either directly or by being formed on an intermediate plate which is fixed to the first substrate 3. As mentioned above, this application can be carried out via varnishing, a PVD process, a CVD process, or the like. A possible protective layer can also be applied after formation of the layer 21. In this step, if the first substrate 3 is translucent, the windows 5 can be formed by selective deposition of the layer 21, as mentioned above.

In step 104, we provide a second substrate 7, which can be made of a material as for the first substrate 3 (see above). In the variant illustrated here, a hollow 13 has already been formed in a zone of the second substrate 7 intended to be opposite the opening 5. This hollow 13 has previously been filled with a luminescent material 11.

In steps 105a, 105b, the two substrates 3, 7 are brought together, and then secured to one another in order to form the dial 1, for example by gluing, welding, screwing, clamping or the like.

Several variants of this method are possible. For example, steps 102 and 103 can take place in an opposite order, that is to say that the layer 21 can be applied on the surface 19 of the substrate 3 before cutting (if necessary). However, this variant requires more handling of the coated substrate, which increases the risk of scratches and other damage to the surface.

The modifications necessary to manufacture the other variants of the dials 1 mentioned above are within the abilities of those skilled in the art, and should not be described in detail.

Although the invention has been described above in connection with specific embodiments, additional variants can also be envisaged without departing from the scope of the invention as defined by the claims.

Claims (16)

1. Dial (1) for a timepiece, comprising: - a first substrate (3) comprising a first surface (19) intended to be located opposite a watch glass and a second surface (20) opposite to said first surface (19), said first substrate (3) comprising in in addition to at least one window (5) serving as an index; - at least a second substrate (7) fixed to said first substrate (3) facing said second surface (20) and associated with a light source (11; 11, 11a), said second substrate (7) comprising a facing area of said at least one window (5); - a tinted layer (21) located on at least a part of said first surface (19) of said first substrate (3); characterized in that said layer (21) comprises carbon nanotubes. 2. Dial (1) according to claim 1, wherein said layer (21) comprises a varnish comprising at least 0.1% by weight, preferably at least 1% by weight, of carbon nanotubes. 3. Dial (1) according to claim 1, wherein said layer (21) comprises carbon nanotubes deposited directly on said surface (19) or on an additional substrate attached to said surface. 4. Dial (1) according to claim 3, wherein at least 20% of the carbon nanotubes extend substantially perpendicular to the plane of said first substrate (3). 5. Dial (1) according to one of claims 1 to 4, wherein the light source (11; 11, 11a) is a luminescent coating deposited on said second substrate (7) at least in said area facing said window. (5), or is a luminescent material in which said substrate (7) is at least partially produced. 6. Dial (1) according to one of claims 1 to 4, wherein the light source (11; 11, 11a) comprises an electric light source. 7. A method of manufacturing a dial (1) for a timepiece, comprising the following steps: - provide a first substrate (3) comprising a first surface (19) intended to be located opposite a watch glass and a second surface (20) opposite said first surface (19), at least one region said first substrate (3) being intended to form at least one window (5) serving as an index; - perforating, where appropriate, said substrate (3) in order to form at least one opening (5) constituting said window; - Applying to at least part of said first surface (19) of the first substrate (3) a layer (21) comprising carbon nanotubes; - providing a second substrate (7) associated with a light source (11, 11a), said second substrate (7) comprising a zone intended to be facing said at least one window (5); - attaching said second substrate to the first substrate facing said second surface (20) so that said area is facing said at least one window (5). The method of claim 7, wherein said first substrate (3) is at least partially transparent, and said layer (21) is selectively applied to define said window (5). 9. Method according to one of claims 7 and 8, wherein said layer (21) is applied as a varnish comprising at least 0.1% by weight, preferably at least 1% by weight, of carbon nanotubes. 10. The method of claim 9, further comprising a step of burning at least a portion of said layer (21) to cause combustion of at least a portion of said varnish. 11. The method of claim 7, wherein said layer (21) is applied by a deposition process. 12. The method of claim 9, wherein at least 20% of the carbon nanotubes extend substantially perpendicular to the plane of said first substrate (3). 13. Method according to one of claims 7 to 12, wherein the light source (11) is a luminescent coating (1) deposited on said second substrate, or is a luminescent material in which said second substrate (7) is at least partially achieved. 14. Method according to one of claims 7 to 12, wherein the light source (11) comprises an electric light source (11). 15. Dial (1) obtained by a method according to one of claims 7 to 14. 16. Timepiece comprising a dial (1) according to one of claims 1-6 and 15.