CH716572A2 - Dial and method of manufacturing a dial for a watch. - Google Patents

Abstract

The invention relates to a dial and a method of manufacturing a dial (2) for a watch. The dial comprises a semi-transparent photovoltaic layer (6) having an underside. On the other hand, the dial also includes a decorative layer (8) based on ink printed on the underside of the photovoltaic layer. The decorative layer includes a pattern including one or more time stamps (20).

Description

Description

Technical area

In general, the invention relates to watch dials, more particularly watch dials comprising a photovoltaic layer.

Technological background

[0002] JP 2005346934 aims to provide a dye sensitized solar cell. The document proposes a solar cell 11 sensitized by a dye equipped with an upper flat glass g1, a lower flat glass g2 facing the upper flat glass. A first dye-sensitized layer 111 is disposed in a first region E1 between the upper flat glass and the lower flat glass. A second dye-sensitized layer 112 is disposed in a second region E2 different from the first region E1. Regions E1 and E2 are located between the upper flat glass and the lower flat glass. The second layer 112a color different from that of the first layer 111.

[0003] JP 2005324517 aims to provide a decorative device. The decorative device is equipped with a dye-sensitized solar cell 11 arranged in a region between a pair of light-transmitting Substrates (eg, an upper glass plate (g1) and a lower glass plate (g2)). A decorative portion 13 is provided to at least one of the pair of Light Transmitting Substrates.

[0004] The scientific publication L. Wen et. al, „Theoretical design of multi-colored semi-transparent organic solar cellswith both efficientcolorfiltering and light harvesting" Sei. Rep. 4 (2014) reports a solar cell incorporating multiple coloring capability providing an aesthetic solution and opening up the possibility of a self-powered color display.

General description of the invention

[0005] A dial is the part of a watch which displays the time by means of one or more time markers (eg indication of a number (12 or XII, 60, etc.) and needles in motion. In its most basic form, the periphery of the dial is numbered from 1 to 12 and indicates the hours on a 12-hour cycle. A first hand makes a revolution every 12 hours. A second hand, longer than the first hand makes one revolution per hour. One or more holes are provided in the dial for the passage of one or more axes of one or more hands.

A first aspect of the invention relates to a dial for a watch The dial comprises a semi-transparent photovoltaic layer having a lower face. On the other hand, the dial also comprises a decorative layer based on ink printed on the lower face of the photovoltaic layer. The decorative layer includes a pattern including one or more time marks.

[0007] The term “photovoltaic layer” is understood to mean a layer which, exposed to light, produces electricity thanks to the photovoltaic effect.

[0008] By "semi-transparent" layer, we mean a layer comprising one or more transparent zones and one or more opaque zones, the layer being, in terms of surface, mostly transparent. Preferably, the surface of the one or more transparent zones is greater to 80%, preferably within a range of 80% to 95%, of the surface of the layer.

[0009] In general, the term “upper” face, surface or side, “above” or “top” of an object means the face, surface or side of the object closest to the user of the watch. It is also the face, surface or side of the object receiving the incident light. Conversely, face, surface or side is understood to mean "lower", "below" or "lower "of an object, the face, surface or side of the object farthest from the eyes of the wearer of the watch (i.e. the face, surface or side opposite to the face, surface or side above ).

[0010] By "ink" is meant a liquid (or possibly a paste) containing one or more pigments or one or more dyes and serving to color a surface in order to produce eg an image, a text or a design.

[0011] By "time mark" is meant any element making it possible to infer the current time thanks to one or more hands of the watch (eg indication of a number (12 or XII, 60, etc.) on the periphery of the dial).

[0012] It will be appreciated that the present invention makes it possible to reduce the number of parts necessary for mounting the dial because the decorative layer is printed on the photovoltaic layer (the decorative layer and the photovoltaic layer are joined together and do not require joining in situ when assembling the watch).

[0013] The pattern preferably comprises a first zone comprising a first ink and a second zone comprising a second ink. The first ink and the second ink being different. Preferably the first zone is central and the second zone is peripheral. By different ink is meant an ink having a different chemical composition from another ink. The decorative layer can be opaque or semi-transparent. It can be plain or have several patterns with or without symmetry. It will be appreciated that great freedom is allowed in terms of decorative patterns.

According to one embodiment, the semi-transparent photovoltaic layer comprises an arrangement of one or more photovoltaic cells covering between 5% and 20%, preferably between 7% and 15%, even more preferably between 9% and 11% of the photovoltaTque layer surface. It will be appreciated that, in this way, a majority of the incident light illuminates the decorative layer.

According to one embodiment, the one or more photovoltaic cells are arranged in a network, the network preferably being a hexagonal, linear or triangular network. According to another embodiment, the network is a mixed network comprising at least two of the following networks: a hexagonal network, a linear network and a triangular network. According to another embodiment, the network could be irregular.

[0016] Preferably, the photovoltaTque layer comprises a protective sub-layer (possibly transparent or semi-transparent), the protective sub-layer being the lower layer of the photovoltaTque layer and being in contact with the decorative layer.

[0017] According to a preferred embodiment, the dial comprises a glossy transparent layer arranged between the semi-transparent photovoltaTque layer and the decorative layer.

According to a preferred embodiment, the photovoltaTque layer comprises an active material having a different sensitivity depending on the wavelength of the incident light. The decorative layer is configured to reflect incident light at a wavelength substantially equal to a sensitivity maximum of the active material. Preferably, the decorative layer is configured to reflect incident light at a wavelength within a range of -150 nm to 150 nm, more preferably within a range of -100 nm to 100 nm, even more preferably within a range ranging from -50 nm to 50 nm centered on a maximum sensitivity of the active material.

[0019] By "sensitivity" of a photovoltaic active material to a wavelength, is meant the capacity of this material to absorb an incident wave at this wavelength and to transform it, by photovoltaic effect, into electrical energy.

A second aspect of the invention relates to a method of manufacturing a dial for a watch. The method includes providing a semi-transparent photovoltaic layer having an underside. The method further comprises applying a decorative ink-based layer to the underside of the photovoltaic layer. The decorative layer includes a pattern including one or more time marks.

[0021] According to one embodiment, the application of the decorative layer is carried out by printing.

According to a preferred embodiment, the application of the decorative layer is carried out by digital printing. The pattern can be applied according to an application plan recorded in a digital printer performing the digital printing.

[0023] Preferably, the printing is carried out by a UV flatbed printer.

[0024] According to one embodiment, the method comprises the application of a glossy transparent layer, the top finishing layer being applied between the semi-transparent photovoltaTque layer and the decorative layer.

A third aspect of the invention relates to a watch comprising the dial according to the first aspect of the invention.

Brief description of the drawings

Other particularities and characteristics of the invention will emerge from the detailed description of certain advantageous embodiments presented below, by way of illustration, with reference to the appended drawings which show:

Fig. 1:

a cross section of a dial of a watch according to a preferred embodiment of the invention;

Fig. 2:

a view of a dial of a watch showing a decorative pattern as well as a network of a photovoltaic cell with one or more Segments according to one embodiment of the invention a hole for the axes of the hands being visible in the center of the dial;

Fig. 3:

a view of a watch dial showing another decorative pattern according to one embodiment of the invention;

Fig. 4:

a graph representing the intensity at zero voltage of a first sample according to one embodiment of the invention as a function of the illuminance required by the sample, according to one embodiment of the invention;

Fig. 5:

a graph representing the zero voltage intensity of a second sample according to one embodiment of the invention as a function of the illuminance received by the sample, according to one embodiment of the invention;

Fig. 6:

a Simulation (ray tracing) showing the increase in illumination of the photovoltaic layer by backscattering of light at the interface glass-printed decorative layer;

Fig. 7: a graph representing the relative increase in the illumination of the photovoltaic layer in

function of the surface filling factor; And

Fig. 8: a graph representing the sensitivity of the active material as a function of the wavelength of the lu

incident mother used in a dial according to a preferred embodiment of the invention.

[0027] The reader's attention is drawn to the fact that the drawings are not to scale. In addition, for reasons of clarity, the proportions between height, length and/or width may not be correctly represented.

Detailed description of a preferred embodiment of the invention

[0028] FIG. 1 shows a cross section of a dial 2 of a watch according to a preferred embodiment of the invention. The dial 2 comprises, from the top to the bottom of the dial, a semi-transparent photovoltaic layer 6, a shiny transparent layer 4 and a decorative layer 8. By top of the dial is meant the part closest to the eyes of the user of the show. The topmost layer is also the layer through which incident light 10 passes first.

[0029] With reference to Figs. 1 and 2, the semi-transparent photovoltaic layer 6 comprises a transparent glass sub-layer 12, one or more photovoltaic cells 14 arranged in a hexagonal network and a protective sub-layer 16. The protective sub-layer 16 structurally stabilizes the hexagonal network of photovoltaic cells14 and protects it against possible shocks. The protective underlayer 16 is in direct contact with the shiny transparent layer 4, in particular, the lower face of the protective underlayer 16 of the photovoltaic layer is in direct contact with the upper layer of the shiny transparent layer 4.

The active material used for one or more photovoltaic cells 14 is based on amorphous silicon. It will however be appreciated that according to other embodiments, the active material may be different.

It will also be appreciated that according to other embodiments, the transparent glass underlayer 12 can be replaced by an underlayer of another transparent material (possibly partially transparent) such as p. eg sapphire or plastic.

Preferably the hexagonal network of photovoltaic cells 14 covers between 5% and 20%, preferably between 7% and 15%, even more preferably between 9% and 11% of the photovoltaic layer surface. It will be appreciated that, in this way, a majority of the incident light 10 illuminates the decorative layer 8.

[0033] The decorative layer 8 is applied to the semi-transparent photovoltaic layer 6, by digital printing. The decorative layer 8 comprises a pattern 18 comprising several time markers 20. The decorative layer 8 can be colored p. ex. in black, white, yellow, purple, etc., and possibly include transparent areas. It will be appreciated that digital printing provides great flexibility in the designs printed. The printing can be done by a UV flatbed printer. The design can be applied according to an application plan saved in a digital printer performing the digital print.

[0034] It will be appreciated that the pattern may comprise a plurality of areas comprising different inks. In particular, according to a preferred embodiment, the decorative layer 8 can comprise a first zone 22 comprising a first ink and a second zone 24 comprising a second ink. The first ink and the second ink are different in the sense that they have p. ex. another chemical composition and/or another color. The time markers 20 can for example be indicated by the second zone 24.

The transparent layer 4 is placed between the semi-transparent photovoltaic layer 6 and the decorative layer 8. The transparent layer 4 can improve the interface between the ink of the decorative layer and the photovoltaic layer 6, p. ex. in the event of physical and/or chemical incompatibility between the ink of the decorative layer 8 and the photovoltaic layer 6.

[0036] A first example of a pattern is illustrated in FIG. 2. The decorative layer 8 includes a first black central zone 22. The first zone 22 comprises four time markers each indicated by a point associated with the numbers "12", "3", "6" and "9" indicated in white. The first zone 22 is surrounded by a peripheral zone 24 of violet color. The pattern of the peripheral zone 24 also includes time markers in the form of a rosette, the points of which are separated between the islands of one 60th of a revolution.

[0037] A second exemplary pattern is illustrated in FIG. 3. The second example is identical to the first except for the choice of colors. In particular, the first central zone 22 is inkless, semi-transparent (the numbers being black in color) and the second peripheral zone 24 is yellow in color.

Examples

The semi-transparent photovoltaic layer comprises a network of one or more photovoltaic cells covering 10% of the surface of the photovoltaic layer. The printing of the decorative layer is carried out by a flatbed UV printer.

[0039] The intensity at zero voltage Isc is proportional to the illuminance received by the sample. The graphs illustrated in Figs. 4 and 5 show typical results of zero voltage intensity Isc as a function of illuminance. Fig.

Claims (15)

4 corresponds to the comparison between a sample with (broken line) or without (solid line) black and violet decorative layer comprising a hexagonal network of photovoltaic cells covering 10% of the surface of the photovoltaic layer. The slopes obtained are respectively 0.113 mA/klx and 0.111 mA/klx. Fig. 5 corresponds to the comparison between a sample with (broken line) or without (solid line) yellow decorative layer comprising a hexagonal network of photovoltaic cells covering 10% of the surface of the photovoltaic layer The slopes obtained are respectively 0.137 mA/klx and 0.119 mA/klx. [0040] It appears that the intensity at zero voltage Isc is only slightly affected by the application of a violet decorative layer, it is even increased by about 2%. In the case of the application of a yellow decorative layer, the intensity at zero voltage Isc a ile, increases by 15%. It follows that depending on the colors chosen for the decorative layer, the photovoltaic efficiency can be improved. The enhancement is due to light backscattered at the glass-printed layer interface and undergoing multiple reflections within the glass underlayer. The light thus reflected improves the yield since an additional part of the incident light reaches the one or more photovoltaic cells. In the absence of a decorative layer, this additional part is lost because it is not reflected and therefore does not reach the one or more photovoltaic cells. [0042] FIG. 6 shows the results of a Simulation (Ray Tracing Simulation) for a sample without decorative layer (circles) and with white decorative layer (crosses). The incident light 10 is characterized by a solar spectrum. The white decorative layer is modeled by a lambertian surface without absorption. The graph represents the illumination of the photovoltaic layer 14 as a function of the surface filling factor comprised between 1% and 100%. The difference between the two samples is represented by squares. [0043] FIG. 7 represents the relative increase in the light incident on the photovoltaic layer 14 as a function of the surface filling factor comprised between 1% and 100%. This curve represents the maximum increase in illumination on the photovoltaic layers due to the light backscattered at the glass-printed layer interface and undergoing multiple reflections inside the glass underlayer since in these simulations, an absorption zero of the decorative layer 8 and of the glass 12 was considered. [0044] FIG. 8 represents the sensitivity curve of the active material (amorphous silicon) as a function of the wavelength of the incident light. In the same figure, the visible colors are also represented as a function of the wavelength. According to the curve, the maximum sensitivity (1 in arbitrary units) of the active material is around 525 nm (green). The sensitivity of the material to the color yellow is about 0.9 (i.e. 90% of the maximum sensitivity of the active material). The sensitivity of the material to the color violet is about 0.55 (i.e. -d. 55% of the maximum sensitivity of the active material). It therefore follows that it is more beneficial to reflect generally yellow light (i.e. to have a generally yellow decorative layer) than to reflect generally violet light (i.e. to have a generally purple decorative layer) in the case of amorphous silicon. [0045] On the other hand, it follows that the efficiency can be increased by increasing the proportion of the white colored surface (reflection of substantially all the colors composing the incident light) with respect to the total surface of the decorative layer or by increasing the proportion of colors whose wavelength is close to the maximum spectral sensitivity of the active material (450 to 600 nm, blue to orange in the case of amorphous silicon). It is obvious for those skilled in the art, on the basis of this document, that the increase in yield depending on the colors could differ for other active materials. The use of fluorescent inks, absorbing outside the maximum sensitivity and emitting close to the maximum sensitivity of the active material, could also improve the yield. In the example of amorphous silicon, the choice could relate to an ink absorbing in the ultraviolet range and emitting in the visible range. Preferably, the emission of this fluorescence could take place at a wavelength comprised in an interval ranging from −150 nm to 150 nm centered on a maximum sensitivity of the active material. [0048] While particular embodiments have just been described in detail, those skilled in the art will appreciate that various modifications and alternatives thereto may be developed in light of the overall teaching provided by this disclosure of the 'invention. Accordingly, the specific arrangements and/or methods described herein are intended to be illustrative only, with no intention of limiting the scope of the invention. Claims 1. A dial for a watch, comprising: a semi-transparent photovoltaic layer having an underside; And a decorative layer based on ink printed on the underside of the photovoltaic layer, the decorative layer comprising a pattern, the pattern comprising one or more time marks. 2. The dial according to claim 1, in which the pattern comprises a first zone comprising a first ink and a second zone comprising a second ink, the first ink and the second ink being different. 3. The dial according to any one of claims 1 to 2, wherein the semi-transparent photovoltaic layer comprises an arrangement of one or more photovoltaic cells covering between 5% and 20%, preferably between 7% and 15%, even more preferably between 9% and 11% of the photovoltaic layer surface. 4. The dial according to claim 3, wherein the one or more photovoltaic cells are arranged in a network. 5. The dial according to claim 4 wherein the network is a hexagonal network, linear, or triangular. 6. The dial according to claim 4 wherein the network is a mixed network comprising at least two of the following networks: a hexagonal network, a linear network and a triangular network. 7. The dial according to any one of claims 1 to 6, wherein the photovoltaic layer comprises a protective underlayer, the protective underlayer being the inner layer of the photovoltaic layer. 8. The dial according to any one of claims 1 to 6, comprising a shiny transparent layer, the transparent layer being placed between the semi-transparent photovoltaic layer and the decorative layer. 9. The dial according to any one of claims 1 to 8, wherein the photovoltaic layer comprises an active material having a different sensitivity depending on the wavelength of the incident light, wherein the decorative layer is configured to reflect light incident at a wavelength substantially equal to a maximum sensitivity of the active material. 10. A method of manufacturing a dial for a watch, comprising: providing a semi-transparent photovoltaic layer having an interior face; applying an ink-based decorative layer to the interior face of the photovoltaic layer, the decorative layer comprising a pattern, the pattern comprising one or more time marks. 11. The manufacturing process according to claim 10, in which the application of the decorative layer is carried out by printing, preferably by digital printing. 12. The manufacturing method according to any one of claims 10 to 11, in which the application of the decorative layer is carried out by digital printing, in which the pattern is applied according to an application plan recorded in a digital printer producing digital printing. 13. The manufacturing process according to any one of claims 11 to 12, in which the printing is carried out by a flatbed UV printer. 14. The manufacturing process according to any one of claims 10 to 13, comprising the application of a glossy transparent layer, the top finishing layer being applied between the semi-transparent photovoltaic layer and the decorative layer. 15. Watch comprising the dial according to any one of claims 1 to 9.