Method for manufacturing a luminous hand

Abstract

The invention relates to a method (500) for manufacturing at least one luminous hand (100) for a timepiece movement, preferably for a watch. The manufacturing method (500) comprises at least a step (510) of providing at least one support (110) comprising at least one light guide (150) and a step (560) of structuring at least one exit surface (190) of the at least one light guide (150) so that a maximum amount of light (910) exits from the at least one luminous hand (100). The at least one luminous hand (100) comprises at least one layer of luminescent material (130) on a lower surface, the at least one layer of luminescent material comprising one or more deposits of fluorescent material opposite a light source (900). The light source (900) is disposed, for example, close to the axis of rotation or at a distance from the axis of rotation but at a distance from the at least one layer of luminescent material (130). Thus, unlike the prior art, the light source (900) is not disposed on the at least one luminous hand (100).

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of luminous hands and more particularly to the manufacturing of luminous hands. BACKGROUND

[0002] There are various methods of making hands for a timepiece movement.

[0003] Nevertheless, these methods are not suitable for manufacturing luminous hands as the result is often that the hand returns only a small amount of light or concentrates most of the light at one point, which is not necessarily the effect sought by the applicant.

[0004] Indeed, certain manufacturing methods result in light being extraire only in one plane of the hand or in light being reflected inwards, thus resulting in a low luminosity of the hand. SUMMARY

[0005] The present invention aims to solve all or part of the aforementioned drawbacks by means of a method for manufacturing at least one luminous hand for a timepiece movement, preferably for a watch; said manufacturing method comprising at least one time:

[0006] - providing at least one support; said at least one support comprising at least one light guide; said at least one light guide comprising at least one exit surface and being configured to guide light; and,

[0007] - structuring said at least one exit surface.

[0008] By means of this arrangement, it is possible to manufacture a luminous hand for a timepiece movement with light dispersion.

[0009] According to one embodiment, said at least one time structuring is performed by erosion, ablation, sandblasting, stamping and / or photostructuring.

[0010] By means of this arrangement, it is possible to increase the light dispersion by increasing said at least one exit surface.

[0011] According to one embodiment, said at least one time providing at least one support comprises depositing at least one layer of a first optical material; said at least one layer of a first optical material having a first refractive index.

[0012] According to one embodiment, said depositing said at least one layer of a first optical material comprises a heat treatment step.

[0013] By means of any of the preceding arrangements, it is possible to manufacture a luminous hand with a reflective layer.

[0014] According to one embodiment, said at least one time providing at least one support comprises at least one time depositing at least one layer of a luminous material.

[0015] By means of this arrangement, a light emitting pointer can be manufactured.

[0016] According to an embodiment, the at least one providing at least one support comprises depositing at least one layer of a second optical material; the at least one layer of the second optical material has a second refractive index.

[0017] According to an embodiment, the first refractive index is lower than the second refractive index.

[0018] By means of this arrangement, light can be refracted towards the at least one exit surface.

[0019] The present invention aims at solving all or part of the above-mentioned drawbacks by means of at least one light emitting pointer comprising at least:

[0020] - a support; the at least one support being configured to form a pointer; and

[0021] - a light guide; the at least one light guide comprising at least one exit surface configured to be rough so as to let light exit from the at least one light guide.

[0022] By means of this arrangement, at least one light emitting pointer can be had which lets a maximum amount of light exit from the at least one exit surface.

[0023] According to an embodiment, the at least one light guide comprises at least one layer of a first optical material having a first refractive index and at least one layer of a second optical material having a second refractive index; the first refractive index being lower than the second refractive index.

[0024] By means of this arrangement, light can be guided towards the at least one exit surface. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present invention will be described in more detail below using the attached drawings, which are given by way of non-limiting example, in which:

[0026] - Figure 1 is shown is a deposition 520 of at least one layer of a first optical material 120 after the provision 510 of at least one support 110 according to an embodiment;

[0027] - Figure 2 is illustrated is a heat treatment step 525 according to an embodiment;

[0028] - Figure 3 is shown is a deposition 530 of at least one layer of a light emitting material 130 according to an embodiment;

[0029] - Figure 4 and Figure 5a step 560 of structuring the at least one exit surface 190 according to one embodiment is shown;

[0030] - Figure 6 a step 560 of structuring the at least one exit surface 190 according to one embodiment is shown;

[0031] - Figure 7 a cut-off 570 of the at least one luminous pointer 100 is shown; and,

[0032] - Figure 8 the at least one luminous pointer 100 in operation is illustrated according to one embodiment. DETAILED DESCRIPTION

[0033] There are several types of luminous pointers on the market. Nonetheless, the Applicant proposes a new generation of luminous pointers.

[0034] Indeed, the Applicant proposes at least one luminous pointer 100 that can be observed in Figure 8 comprises at least one support 110 configured to form a pointer and at least one light guide 150 comprising at least one exit surface 190 configured to be rough so as to exit light 910 from the at least one light guide 150.

[0035] By means of the manufacturing method 500 of the Applicant, the at least one luminous pointer 100 intended to be used in a timepiece movement, preferably for a watch, can be obtained. To this end, the manufacturing method comprises at least one time of providing 510 at least one support 110, preferably a metal sheet 110, such as Figure 1 shown.

[0036] The at least one support 110 receives at least one layer of a first optical material 120 having a first refractive index, preferably at least one light insulation layer, during a deposition 520, which allows to prevent light from being absorbed by the metal sheet 110, after which a heat treatment 525 is carried out at a determined temperature 521. Before the deposition 520 of the at least one layer of first optical material 120, the metal sheet 110 or the at least one support 110 can be cleaned, to which a plasma treatment can then be applied in order to promote the adhesion of the at least one layer of first optical material 120. In this case, the at least one layer of first optical material 120 can be, for example, a resin sold by the company POLYRISE TM and intended to optically insulate the surface of the at least one support 110 so that it absorbs as little light as possible. By means of the first refractive index, which cannot be greater than 1.60, in particular 1.45, preferably 1.35, such optical insulation is made possible.

[0037] The at least one first optical material 120 can be deposited, for example, by printing or spraying, as spraying allows to selectively deposit the at least one first optical material 120 on the useful part and to avoid waste.

[0038] As previously mentioned, the at least one first optical material 120 is subjected to the heat treatment 525 under nitrogen at 300°C, for example, for one hour, so that the solvent of the at least one first optical material 120 can evaporate, which can be observed in Figure 2 .

[0039] As Figure 3 illustrated, at least one layer of luminescent material 130 can be deposited 530 on the at least one support 110, preferably above the at least one first optical material 120, at least once. The at least one layer of luminescent material 130, which preferably comprises a fluorescent pigment and a binder that enables attachment by polymerization, is intended to make the at least one luminescent pointer 100 luminescent when the at least one layer of luminescent material 130 is illuminated by a light source with a wavelength range less than, for example, 530 nm.

[0040] Indeed, the fluorescent pigment can be a secondary light source. In a watch, the fluorescent pigment can be excited from a distance by, for example, a blue or ultraviolet light source. It should be noted that other techniques such as screen printing or digital printing can be used for the at least one deposition 530 of the at least one layer of luminescent material 130.

[0041] A UV plasma treatment is then carried out for a few minutes to promote the adhesion of the at least one second optical material 140, which is, for example, a 10 resin type from the company MICRORESIST Technology TM . The treatment is carried out by deposition 540 of the rod type or of the doctor blade type (also known as brush coating, as illustrated, for example, in Figure 4 .

[0042] Still referring to Figure 4 , it can be observed that the at least one layer of second optical material 140 can be pushed with a blade to fill the various cavities that can be present.

[0043] It should be noted that the at least one layer of second optical material 140 has a second refractive index greater than the first refractive index to guide the fluorescence emitted by the at least one layer of luminescent material 130.

[0044] As can be seen in Figure 5 , the at least one layer of second optical material 140 can be fixed by exposure to ultraviolet light 552 under vacuum 551. Alternatively, a plastic film can be laminated in order to expel the air before exposure to ultraviolet light.

[0045] Indeed, the lower surface of the at least one second optical material 140 comprises one or more fluorescent material deposits opposite the light source 900 so as to establish an optical link with the at least one luminescent material 130, and as mentioned previously, the at least one luminescent material 130 can be formed of fluorescent pigments incorporated in a glue. Alternatively, the fluorescent material can be incorporated in the light guide layer.

[0046] In operation, the light source 900 causes the at least one luminescent material 130 to emit light, the wavelength of which is shorter than the wavelength that will be re-emitted by the at least one luminescent material 130. The at least one luminescent material 130 absorbs this incident light and re-emits it 910, in particular into the at least one second optical material 140. The presence of the at least one first optical material 120 enables total internal reflection of the fluorescent light propagating in the at least one second optical material 140, thus avoiding progressive absorption in the at least one support 110.

[0047] The difference in refractive index between the at least one support 110 and the at least one second optical material 140 is in the interval ranging from 0.5 to 0.9, preferably from 0.55 to 0.8, more preferentially from 0.6 to 0.75, which allows increasing the value of the critical angle and thus the numerical aperture of the at least one second optical material 140 so as to maximize the coupling of the fluorescent light. It should be noted that the presence of the at least one first optical material 120 enables lossless transmission in the at least one second optical material 140 once the light is coupled, and the refractive index of the at least one first optical material 120 influences the amount of coupled light. The thickness of the at least one first optical material 120 can be in the interval ranging from 2 pm to 15 pm, preferably from 3 pm to 12 pm, more preferentially from 5 pm to 10 pm. The succession of total internal reflections in the at least one second optical material 140 continues until reaching one end of the at least one luminescent pointer 100, where the light flow propagates outwards.

[0048] Finally, the step 560 of structuring the at least one exit surface 190, schematically illustrated in Figure 6 may be performed by erosion 565, ablation 565, sandblasting 565, stamping 565 and / or photostructuring 565, so as to increase the at least one exit surface 190 and / or so as to completely or partially avoid the re-refraction of the light 910 which would result in, for example, a concentration of the light on a point. Indeed, it is possible to provide a surface structuring, i.e. a partial stripping of the material of the at least one second optical material 140, so as to introduce roughness on the at least one exit surface 190 of the at least one second optical material 140, thus facilitating the exit of the light 910 therefrom.

[0049] Moreover, the at least one light-emitting pointer 100 can be added with a light-diffusing zone, made by depositing resin, which extends beyond the at least one support 110, i.e. protrudes from the at least one support 110, to facilitate the outflow of the light flow and obtain a decorative pattern on the tip. According to an embodiment not shown, not only the tip of the at least one light-emitting pointer 100, but also the edges and optionally the head of the at least one light-emitting pointer 100 comprise the at least one exit surface 190.

[0050] The step 570 of cutting the at least one light-emitting pointer 100 is carried out, for example, by means of a laser 571, since the laser 571 can melt the at least one light guide 150 consisting of the at least one layer of first optical material 120 and at least one layer of second optical material 140 and produce a shiny surface condition, Figure 7 which allows the light 910 to be reflected towards the inside of the at least one light guide 150.

[0051] In the example of Figure 8 , the at least one exit surface 190 corresponds to the peripheral surface of the at least one light-emitting pointer 100 to make the profile of the at least one light-emitting pointer 100 light up. In fact, when the at least one layer of luminescent material 130 is subjected to the light source 900 with a wavelength between 330 nm and 560 nm, the at least one layer of luminescent material 130 generates the light 910 which exits via the at least one exit surface 190 of the at least one light guide 150. Of course, it is also possible to provide a light source LED in a suitable position of the product in question, for example close to the axis of rotation or far from the axis of rotation, and to add a light coupler which allows the light flow of the light source 900 to be brought to the suitable position to excite the fluorescent material of the at least one light-emitting pointer 100. Therefore, unlike the prior art, the light source 900 is not provided on the at least one light-emitting pointer 100.

Claims

1. A method (500) for manufacturing at least one luminous hand (100) for a timepiece movement; the manufacturing method (500) comprising at least one of: - providing (510) at least one support (110) supporting a luminous hand (100); - forming a light guide (150) on the at least one support (110), the light guide (150) comprising at least one exit surface (190) and being configured to guide light (910), the forming step comprising the following sub-steps: - depositing (520) at least one layer of a first optical material (120) on the support (110), the at least one layer of a first optical material (120) having a first refractive index and allowing to prevent light from being absorbed by the support (110); - depositing (530) at least one layer of a luminous material (130) over the at least one layer of a first optical material (120); - depositing (540) at least one layer of a second optical material (140); the at least one layer of a second optical material (140) having a second refractive index; and, - structuring (560) the at least one exit surface (190) so that the exit surface (190) is rough to make light (910) exit from the at least one light guide (150).

2. The manufacturing method (500) of claim 1, wherein, The at least one structuring (560) is performed by erosion, ablation, sandblasting, stamping and / or photo structuring.

3. The manufacturing method (500) of claim 1, wherein, The depositing (520) of the at least one layer of a first optical material (120) comprises a heat treatment step (525).

4. The manufacturing method (500) according to any one of claims 1 to 3, wherein The at least one depositing (530) of at least one layer of a luminous material (130) comprises a fluorescent pigment.

5. The manufacturing method (500) according to any one of claims 1 to 3, wherein, The first refractive index is lower than the second refractive index.

6. The manufacturing method (500) according to any one of claims 1 to 3, wherein The at least one luminous hand (100) is used for a watch.

7. A luminous hand (100) for a timepiece movement, comprising at least one of: - a support (110) supporting the hand; - a light guide (150); the at least one light guide (150) comprising: - at least one layer of a first optical material (120) having a first refractive index and allowing to prevent light from being absorbed by the support (110); - at least one layer of a luminous material (130) over the at least one layer of a first optical material (120); - at least one layer of a second optical material (140) having a second refractive index; and an exit surface (190) configured to be rough to make light (910) exit from the at least one light guide (150).

8. The luminous hand (100) according to claim 7, wherein The first refractive index is lower than the second refractive index.

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