CH720369A2 - Watch dial including a lighting device - Google Patents

Abstract

One aspect of the invention relates to a watch dial (2a) comprising an autonomous lighting device (3) comprising the following functional elements: – at least one light source (4), – an autonomous electrical power supply unit (21 ), and – a control unit (7) for managing the operation of said at least one light source (4), said dial (2a) being formed by an assembly (9a) of a plurality of superimposed layers (10, 11, 12, 13) interconnected and each comprising one or more functional elements of the autonomous lighting device (3).

Description

Technical field of the invention

[0001] The present invention relates to a watch dial equipped with a completely autonomous lighting device.

Technology background

[0002] In the prior art, different types of lighting devices have been proposed for watches in order to allow reading of the time in low light conditions. These devices are essentially based on the presence of phosphorescent materials on the dials of these watches. Such materials have been used with more or less success because all suffer from the well-known disadvantage of having an effectiveness that decreases over time. Additionally, these materials generally require periodic recharging through exposure to light so that the level of phosphorescent emissions is maintained.

[0003] In this context, we understand that there is a need to find a solution which does not present the disadvantages of the prior art.

Summary of the invention

[0004] The invention aims to overcome these drawbacks by proposing a watch whose illumination of its dial has an efficiency which remains constant over time.

[0005] One aspect of the invention relates to a watch dial comprising an autonomous lighting device comprising the following functional elements: - at least one light source, - an autonomous electrical power supply unit, and - a control unit for manage the operation of said at least one light source, said dial being formed by an assembly of a plurality of superimposed layers connected to each other and each comprising one or more functional elements of the autonomous lighting device.

[0006] Another aspect of the invention concerns... – the assembly consists of a first layer forming a visible face of the dial comprising at least one light source; – said first layer is configured to be traversed in whole or in part by light radiation, in particular by solar radiation – said first layer is entirely or partly transparent or translucent; – the assembly comprises a second layer comprising a photovoltaic module constituting the autonomous power supply unit; – the second layer comprises a substrate on which the photovoltaic module is printed; – said photovoltaic module is arranged on an active zone of said second layer, said zone being configured to receive light radiation coming from the first layer of the assembly; – the assembly comprises a third layer comprising an electrical energy accumulator constituting the autonomous electrical power supply unit; – the third layer comprises a substrate on which the electrical energy accumulator is printed; – the assembly comprises a fourth layer forming a hidden face of the dial comprising the control unit; – the assembly comprises a third layer comprising a hidden face of the dial comprising the control unit and an electrical energy accumulator constituting the autonomous electrical power supply unit; – the first layer is rigid relative to the other layers included in the assembly which are flexible.

Another aspect of the invention relates to a watch comprising such a dial.

[0008] Advantageously, the watch comprises a mechanical or electromechanical or electronic watch movement.

Brief description of the figures

[0009] The aims, advantages and characteristics of the watch according to the invention will appear better in the following description on the basis of at least one non-limiting embodiment illustrated by the drawings in which: – Figure 1 represents a view in perspective of a watch comprising a dial provided with an autonomous lighting device, according to embodiments of the invention; – Figure 2 represents an exploded view of a first variant of the assembly of four superimposed layers forming said dial provided with the autonomous lighting device, said layers each comprising one or more constituent elements of the lighting device, according to a first embodiment of the invention; – Figure 3 represents a schematic view of this first variant of the assembly of layers forming the dial provided with the autonomous lighting device according to the first embodiment of the invention; – Figure 4 represents an exploded view of a second variant of the assembly of three superimposed layers forming said dial provided with the autonomous lighting device, said layers each comprising one or more constituent elements of the lighting device according to a second mode embodiment of the invention, and – Figure 5 represents a schematic view of this second variant of the assembly of layers forming the dial provided with the autonomous lighting device according to the second embodiment of the invention.

Detailed description of the invention

[0010] Figure 1 illustrates a schematic representation of a watch 1 comprising a case 19 provided with a middle to which are fixed a back and a crystal 22, a set of components forming a watch movement, and a dial 2a, 2b placed between the watch movement and the crystal 22.

[0011] The watch movement drives, in a manner known to those skilled in the art, a switch comprising an hour hand, a minute hand and possibly a second hand. For this purpose, the dial 2a, 2b has a through hole receiving the axis of the hands. This dial 2a, 2b also includes two faces 20a, 20b including: - a so-called visible face 20a from the outside of the watch 1 also called "visible part" or "visible upper part" of this dial 2a, 2b, and - a so-called hidden face 20b arranged opposite the watch movement in an enclosure of the case 19 of the watch 1, this face 20b being otherwise called “hidden part” or “hidden lower part” of this dial 2a, 2b, 2b.

[0012] Such a visible face 20a comprises at least one graphic representation such as: – a reference (or display) element such as for example a number, an index, a line or even a point contributing to participation with/without the hands displaying horological information/quantity or physical information/quantity measured by a sensor or the like included in the movement; – an inscription, a pattern, a text, a logo, etc.

[0013] It will also be noted that in the embodiments illustrated in Figures 1 to 5, the dial 2a, 2b preferably has a circular shape. It is understood that the invention can also be implemented for dials 2a, 2b having other shapes such as for example a triangular shape or even a shape similar to that of a quadrilateral.

[0014] In the embodiments of the invention, the watch movement is a mechanical movement. Alternatively, this movement can be an electronic movement or even an electromechanical movement. We will subsequently speak of a mechanical watch when its movement is mechanical and of electromechanical and electronic watches when they respectively comprise electromechanical and electronic movements.

With reference to Figures 2 and 4, such a dial 2a, 2b comprises an independent lighting device 3. This lighting device 3 includes its own electrical power supply means as we will see later. Such a lighting device 3 is said to be autonomous in particular with respect to the movement of the watch 1 and in particular the energy source of this movement, for example when this source is an electrical power supply as in an electronic movement or an electromechanical movement. Under these conditions, we understand that the energy used by this lighting device 3 is not to the detriment of the autonomy of the movement.

[0016] In this context, the dial 2a, 2b can be removably mounted in the watch 1 whatever the type of watch 1. The only condition to be respected is that the dial 2a, 2b includes this lighting device 3 which is therefore independent from the movement of watch 1.

This lighting device 3 included in this dial 2a, 2b, comprises at least one light source 4 also called light source, an independent electrical power supply unit 21 and a control unit 7.

[0018] In this context, the light source 4 can correspond to any electroluminescent element selected from a list comprising in a non-exhaustive and non-limiting manner: – an electroluminescent capacitor better known by the acronym LEC for “Light-Emitting Capacitor “ ; – a light-emitting diode such as LED (acronym for “Light-Emitting Diode”), OLED (acronym for “Organic Light-Emitting Diode”), AMOLED (acronym for “Active-Matrix Organic Light-Emitting Diode”) or even QLED ( acronym for “Quantum Light-emitting diode”; – any electroluminescent material activated by a local electric field; – any electroluminescent material activated by an electric current;

[0019] It will be noted that this light source 4 can, in certain embodiments of the invention, be a light source 4 capable of forming an extended light source. This makes it possible to give a predetermined shape to the extended light source, typically, without this being exhaustive or limiting, a shape relating to a graphic representation of a number, letter, logo or even text. It will also be noted that this light source 4 can produce light in any color and/or in any direction.

[0020] In this lighting device 3, the independent electrical power supply unit 21 comprises an electrical energy accumulator 6 and a photovoltaic module 5 comprising at least one photovoltaic cell also called solar cell. This photovoltaic module 5 is connected to the electrical energy accumulator 6 via connection elements referenced 17b and 18 in Figures 3 and 5. This photovoltaic module 5 may comprise one or more elementary cells of the heterojunction or multijunction type, connected in parallel or in series. Each photovoltaic cell of this module 5 can be made, in a manner known to those skilled in the art, from semiconductor materials based on copper, indium, gallium and selenium, based on cadmium telluride , based on monocrystalline gallium arsenide or based on monocrystalline or polycrystalline silicon, or with perovskites. It should be noted that these examples are non-limiting and that those skilled in the art will be able to find the type of photovoltaic cell suitable for the invention.

[0021] In this lighting device 3, the control unit 7, also called a microcontroller, comprises an electronic circuit 8 comprising hardware resources, in particular at least one processor cooperating with memory elements as well as address buses, data and control. This control unit 7 comprises in its memory elements an algorithm for managing the illumination of said at least one light source 4. Such an algorithm is executed by the processor of this control unit 7 taking into account in particular data coming from event sensors included in the lighting device 3 in order to ensure management of the operation of said at least one light source 4.

[0022] It will be noted that such data can for example provide information relating to events detected by these sensors, said events being capable of contributing to the operation of said at least one light source 4. These events can include, in a non-limiting manner and non-exhaustive: the detection of a particular level of brightness in the environment of the watch 1, the detection of a particular sound element or a particular sound level, the detection of a particular visual object, the detection of a movement carried out by a part of the user's body on which this watch 1 is included, etc.

[0023] In this context, the event sensor of this autonomous lighting device 3, comprises in particular and in a non-limiting and non-exhaustive manner: – a brightness sensor making it possible to detect the ambient brightness level; – a movement sensor of a part of the user's body comprising the watch 1 such as a gyroscopic and/or inertial sensor in the form of an electronic component of the gyroscopic and/or inertial electromechanical microsystems circuit type; – a microphone-type sound sensor, and/or – an optical sensor such as a photographic sensor.

Furthermore, when the lighting device 3 comprises several light sources 4, the operation of the latter can then be managed/controlled by the control unit 7 simultaneously and/or in sequence. In addition, each light source 4 is managed/controlled by this control unit 7 in a separate manner. In this context, the management of the operation of each light source 4 can consist in a non-limiting and non-exhaustive manner of carrying out the following operations: a sequential switching on or off (the), a simultaneous switching on or off (e) of two or more light sources 4, a flashing of one or more light sources 4, a definition of a flashing frequency for each light source 4, a flashing duration for each light source 4, an on or off duration extinction for each light source 4, etc.

Such a control unit 7 can also include in its memory elements an algorithm for managing the electrical energy accumulator 6, in particular the management of its recharging by the photovoltaic module 5 and the management of electrical consumption by said light source 4.

As we have mentioned, the autonomous lighting device 3 is therefore included in the dial 2a, 2b. In this configuration, the constituent elements of this lighting device 3, namely the light source 4, the electrical energy accumulator 6, the photovoltaic module 5 and the control unit 7, are included in one or more layers 10, 11, 12, 13, 14 forming this dial 2a, 2b.

With reference to Figures 2 to 5, this dial 2a, 2b is formed by an assembly 9a, 9b of a plurality of layers 10, 11, 12, 13, 14 of material connected together. In this assembly 9a, 9b, these layers 10, 11, 12, 13, 14 are connected together by a connecting element such as an adhesive substance so as to unify them in order to obtain a monolithic assembly 9a, 9b thus forming a dial monobloc 2a, 2b. This connecting element can also be a clip or even a screw. Such layers 10, 11, 12, 13, 14 are superimposed in the assembly 9a, 9b, that is to say they are arranged one above the other in this dial 2a, 2b in a defined order .

[0028] Thus such a one-piece dial 2a, 2b also has the advantage of being able to be mounted removably in the case 19 of the watch 1 in addition to facilitating its integration into this case 19.

[0029] In a first variant of this assembly 9a illustrated in Figure 3, the latter is made up of four successive layers 10, 11, 12, 13 following: – a first layer 10 forming/constituting the visible face 20a of the dial 2a including said at least one light source 4 of the lighting device 3, – a second layer 11 including the photovoltaic module 5; – a third layer 12 including an electrical energy accumulator 6 also called a rechargeable battery, and – a fourth layer 13 forming the hidden face 20b of the dial 2a including the control unit 7.

The first layer 10 of this assembly 9a is preferably rigid or semi-rigid in comparison with the second, third and fourth layers 11, 12, 13 which are preferably soft or flexible. We understand here that such a first layer 10 contributes to structurally stiffening the assembly 9a and therefore the dial 2a.

[0031] In this assembly 9a, the first, second, third and fourth layers 10, 11, 12, 13 each comprise an upper surface and a lower surface.

With regard to the first layer 10, it is formed by a transparent or translucent or at least partially transparent or at least partially translucent substrate which is rigid or semi-rigid. Such a substrate is made of a material having a transmittance to solar radiation, in particular to ultraviolet radiation, also called UVT (for “Ultra-Violet Transmission”) which is between 65 and 95 percent. This transmittance is preferably 85 percent. Such a material can be transparent or translucent. This material can be, in a non-limiting and non-exhaustive manner, a polymer, glass or even ceramic.

[0033] In this context, we understand that this substrate is configured so that: – the light produced by said at least one light source can escape towards the outside of the dial 2a, 2b and therefore of the watch 1, and – the light coming from the environment of the watch 1 can penetrate the dial 2a, 2b towards the photovoltaic module 5 of the lighting device 3, this light comprising solar radiation when it is of natural origin.

In other words, this transparent or translucent substrate is configured to be crossed by solar radiation capable of supplying the photovoltaic module 5 so that the latter can convert the solar energy coming from this radiation into electrical energy.

This first layer 10 also comprises at least one light source 4 which is arranged in the body of the substrate. Such an arrangement of the light source 4 in this substrate is configured to ensure illumination of all or part of the visible face 20a of the dial 2a. For example, lighting of a graphic representation such as a reference element (or display) such as a number, an index, a line, a point or lighting of one or more hands, or even lighting of any or part of the surface of the visible face of dial 2a. In a variant, this light source 4 can have a predetermined shape such as the shape of a number, a letter, an index, a line, a point, a logo or even a a text.

This lighting can be backlighting or semi-direct type lighting when the light source 4 is arranged in a cavity defined in the substrate. More precisely, this cavity can be a blind opening made in the lower surface of this substrate. In this configuration, when the bottom of this cavity includes a graphic representation, the light radiation, or the light, produced by this light source 4 can escape towards the outside of the dial 2a via the visible face 20a of this dial 2a, thus allowing the visualization of at least one graphic representation in the dark. In particular, the light radiation thus escaping from the visible face 20a, draws the outline of this graphic representation. In this context, this graphic representation included in or on the upper surface or even on the lower surface of the substrate forming the first layer 10, is preferably opaque or non-translucent or non-transparent.

This lighting can be direct lighting when the light source 4 is arranged in a cavity defined in the substrate. This cavity can be a blind opening made in the lower surface of this substrate and the bottom of which is devoid of any graphic representation. In this configuration, the light radiation, or light, produced by this light source 4 can escape through the bottom of this cavity towards the outside of the dial 2a and therefore through the visible face 20a of this dial 2a.

[0038] This lighting can also be direct lighting when the light source 4 is arranged in a through opening extending into the thickness of the substrate of the first layer 10, opening at its two ends respectively into the upper and lower surfaces of this substrate. In this configuration, all or part of the light source 4 can project from the upper surface of this substrate and therefore from the first layer 10 or from the visible face 20a of the dial 2a to form a graphic representation such as an index, a number, point, line, etc.

Such lighting can also be offset lighting when said at least one light source 4 is coupled to at least one waveguide. This wave guide, also called a light guide, makes it possible to bring the light from the point where it is injected into the guide into the substrate or to a zone of the substrate (e.g.: cavity, through opening) near of the upper surface of this substrate. Such a light guide can be an optical fiber which makes it possible to bypass any obstacles which may arise in the substrate, for example between the electroluminescent element and the zone of the substrate close to the upper surface of this substrate, through which the light goes. escape. In this alternative embodiment, it is therefore the light which is brought, via the waveguide, from the electroluminescent element to this zone of the substrate to be illuminated.

[0040] In such a configuration, a first end of the waveguide is coupled with the light source 4 and a second end of this guide can be arranged in: – a cavity which can be a blind opening made in the lower surface of the substrate of this first layer 10, or – a through opening extending into the thickness of the substrate of the first layer 10, opening at its two ends respectively into the upper and lower surfaces of this substrate and therefore of the first layer 10. Thus this second end can project from the upper surface of the substrate or from this first layer 10 or from the visible face 20a of the dial 2a in order for example to form a graphic representation of this dial 2a such as for example a reference element such as a index, a number, a point, a line, etc.

[0041] In this context, indirect lighting can be achieved by a single light source 4 included on the lower surface of the substrate of this first layer 10 while being coupled to several waveguides whose second ends are arranged in: – cavities each emitting light radiation, coming from this light source 4, this radiation escaping towards the outside of the dial 2a via the visible face 20a, thus authorizing the visualization of at least one graphic representation in the dark. In this context, this graphic representation included in or on the visible face 20a of the dial 2a, or the upper surface of the substrate, is preferably opaque, and/or - through openings projecting or not from the upper surface of this substrate in order to form marker elements such as an index, line or even a point, and each emitting light radiation, coming from this light source 4.

[0042] In this first layer 10, the light source 4 is applied/fixed to the lower surface of the substrate of this first layer 10, in a cavity or on an internal wall of a through opening mentioned above, by printing or evaporation.

[0043] Furthermore, it will be noted that the lower surface of this first layer 10 can be self-adhesive in order to participate in its assembly with the second layer 11.

[0044] In this assembly 9a, the second layer 11 comprises a substrate comprising the photovoltaic module 5. Such a substrate is preferably flexible or flexible. This substrate of the second layer 11 can be a film on which the photovoltaic module 5 is placed. Finally, this substrate can be made of a material belonging to the polymer family.

[0045] In this second layer 11, the photovoltaic module 5 extends preferentially over the entire so-called active zone of the upper surface of this substrate. This active zone is a portion of the upper surface of the substrate which is able to receive the light coming from the lower surface of the first layer 10 of the dial 2a. This light which has passed through all or part of the first layer 10, comes from the external environment of the dial 2a, and therefore from the watch 1, here mainly from solar radiation when it is of natural origin.

[0046] It will be noted that the photovoltaic module 5 is applied to the upper surface of this substrate using inkjet printing processes or even by screen printing or using thermal evaporation printing processes. We will also speak here of a second layer 11 comprising a printed photovoltaic module 5. In particular, a photovoltaic module 5 printed on the substrate of the second layer 11.

It will be noted that once the photovoltaic module 5 has been applied to the substrate, a layer of a self-adhesive substance can be deposited on all or part of the upper surface and/or the lower surface of the substrate. Under these conditions, the second layer 11 can be a self-adhesive layer which helps to facilitate its assembly with the other layers in particular with the first layer 10 and/or the third layer 12 of this assembly 9a.

[0048] In assembly 9a, this third layer 12 also comprises a preferably flexible or flexible substrate, comprising the electrical energy accumulator 6 of the autonomous lighting device 3. This substrate of the third layer 12 can be a film on which the accumulator 6 is included. Such a substrate can be made of a material belonging to the polymer family.

This accumulator 6 can be a lithium battery or even a semiconductor battery. Such an accumulator 6 is applied to the upper surface of this substrate using processes known from the state of the art such as: – printing processes on a flexible polymer substrate when it is, for example, a battery lithium, or – three-dimensional printing processes when it concerns for example a solid-state battery such as a solid-state lithium-metal battery.

[0050] We will also speak here of a third layer 12 comprising a printed electrical energy accumulator 6. In particular, an electrical energy accumulator 6 printed on the substrate of the third layer 12.

[0051] Thus, such methods make it possible to obtain a third layer 12 comprising this accumulator 6 which is flexible and ultrathin.

[0052] Furthermore, it will be noted that once the accumulator 6 is applied to the substrate, a layer of a self-adhesive substance can be deposited on all or part of the upper surface and/or the lower surface of this substrate. Under these conditions, the third layer 12 can be a self-adhesive layer which helps to facilitate its assembly with the other layers in particular with the second layer 11 and/or the fourth layer 13 of this assembly 9a.

It will be noted that this accumulator 6 serves to store the electrical energy produced by the photovoltaic module 5 and to restore it on demand to power said at least one light source 4.

[0054] In this assembly 9a, this fourth and final layer 13 forms the hidden face of the dial 2a. Such a fourth layer 13 is formed by a preferably flexible or flexible substrate, comprising the control unit 7. Such a substrate of the fourth layer 13 can for example be a flexible PCB on which this control unit 7 is arranged in particularly on the upper surface of this PCB and therefore of the substrate. In this context, the construction of the control unit 7 on this upper surface of the substrate can be carried out using three-dimensional printing processes or even polymer printing processes.

[0055] In the second variant, the assembly 9b forming the dial 2b comprises three layers 10, 11, 14, connected together. It will be noted that this second variant differs from the first variant in that it therefore comprises three layers 10, 11, 14 instead of four layers 10, 11, 12, 13, as in the first variant. In this second variant, the electrical energy accumulator 6 of the autonomous lighting device 3 is now included in the third and last layer 14 of this assembly 9b with the control unit 7.

Such a third and final layer 14 of this assembly 9b, forming the hidden face of the dial 2b, is made up of a preferably flexible or flexible substrate, on which are built, preferably on the upper surface of this substrate, the accumulator 6 and the electronic circuit 8 constituting the control unit 7. Such construction of the accumulator 6 and the control unit 7 on this upper surface of the substrate can be carried out using printing processes three-dimensional or even polymer printing processes. It will be noted that such a substrate can be, for example, a flexible PCB.

[0057] In summary, in this second variant, the assembly 9b then comprises: – a first layer 10 forming the visible face 20a of the dial 2b including said at least one light source 4 of the lighting device 3; – a second layer 11 including the photovoltaic module 5, and – the third layer 14 forming the hidden face 20b of the dial 2b including the accumulator 6 and the control unit 7.

It will be noted that in this second variant, the first and second layers 10, 11 are similar to those of the first variant of the assembly 9a.

[0059] Furthermore, with reference to Figures 3 and 5, the electronic circuit 8 of the control unit 7 comprises first connection elements 15a which are connected to connection elements 16 of said at least one light source 4 for managing the operation of this light source 4. This electronic circuit 8 also includes second connection elements 15b connected to first connection elements 17a of the accumulator 6.

[0060] Furthermore, it will be noted that the event sensors of the lighting device 3, mentioned previously, are preferably arranged in the first layer 10 and/or the last layer 13, 14 of the assembly 9a, 9b, being connected to the control unit 7 of this device 3.

[0061] In a third variant not shown, the assembly forming the dial comprises two layers connected together. It will be noted that this third variant differs from the second variant in that it therefore comprises two layers instead of three layers 10, 11, 14, as in this second variant. In this third variant, the photovoltaic module 5 of the autonomous lighting device 3 is now included in the first layer and in particular on the lower surface of the substrate forming this first layer. This photovoltaic module 5 can be applied to this lower surface of the substrate of this first layer using inkjet printing processes or even by screen printing or using thermal evaporation printing processes. It will therefore be noted that this first layer is then similar to the first layers 11 of the first and second variants, with the exception of the fact that in this third variant, the first layer additionally comprises the photovoltaic module.

[0062] Furthermore, in the third variant, and in a manner similar to the second variant, the electrical energy accumulator 6 of the autonomous lighting device 3 is included in the second and last layer of this assembly with the unit of control 7. Such a second layer forming the hidden face of the dial, is made up of a preferably flexible or flexible substrate, on which the accumulator 6 and the electronic circuit 8 are built, preferably on the upper surface of this substrate. constituting the control unit 7. This construction of the accumulator 6 and the control unit 7 on the upper surface of the substrate, can be carried out using three-dimensional printing processes or even polymer printing processes . It will be noted that such a substrate can be, for example, a flexible PCB.

[0063] In summary, in this third variant, the assembly then comprises: – a first layer forming the visible face 20a of the dial including said at least one light source 4 and the photovoltaic module 5 of the lighting device 3, and – a second layer forming the hidden face 20b of the dial including the accumulator 6 and the control unit 7.

[0064] It goes without saying that the present invention is not limited to the embodiments which have just been described and that various simple modifications and variants can be envisaged by those skilled in the art without departing from the scope of the invention. as defined by the appended claims.

Claims (14)

1. Dial (2a, 2b) of watch (1) comprising an autonomous lighting device (3) comprising the following functional elements: – at least one light source (4), – an autonomous power supply unit (21), and – a control unit (7) for managing the operation of said at least one light source (4), said dial (2a, 2b) being formed by an assembly (9a, 9b) of a plurality of superimposed layers (10, 11, 12, 13, 14) connected together and each comprising one or more functional elements of the device autonomous lighting (3). 2. Dial (2a, 2b) according to the preceding claim, characterized in that the assembly (9a, 9b) consists of a first layer (10) forming a visible face (20a) of the dial (2a, 2b) comprising at least one light source (4). 3. Dial (2a, 2b) according to any one of the preceding claims, characterized in that said first layer (10) is configured to be traversed in whole or in part by light radiation, in particular by solar radiation. 4. Dial (2a, 2b) according to any one of the preceding claims, characterized in that said first layer (10) is entirely or partly transparent or translucent. 5. Dial (2a, 2b) according to any one of the preceding claims, characterized in that the assembly (9a, 9b) comprises a second layer (11) comprising a photovoltaic module (5) constituting the power supply unit autonomous electric (21). 6. Dial (2a, 2b) according to any one of the preceding claims, characterized in that the second layer (11) comprises a substrate on which the photovoltaic module (5) is printed. 7. Dial (2a, 2b) according to any one of claims 5 and 6, characterized in that said photovoltaic module (5) is arranged on an active zone of said second layer (11), said zone being configured to receive light radiation coming from the first layer (10) of the assembly (9a, 9b). 8. Dial (2a) according to any one of the preceding claims, characterized in that the assembly (9a) comprises a third layer (12) comprising an electrical energy accumulator (6) constituting the electrical power supply unit (21) autonomous. 9. Dial (2a) according to the preceding claim, characterized in that the third layer (12) comprises a substrate on which the electrical energy accumulator (6) is printed. 10. Dial (2a) according to any one of the preceding claims, characterized in that the assembly (9a) comprises a fourth layer (13) forming a hidden face (20b) of the dial (2a) comprising the control unit (7). 11. Dial (2b) according to any one of claims 1 to 7, characterized in that the assembly (9b) comprises a third layer (14) comprising a hidden face (20b) of the dial (2a) comprising the unit control unit (7) and an electrical energy accumulator (6) constituting the autonomous electrical power supply unit (21). 12. Dial (2a, 2b) according to any one of the preceding claims, characterized in that the first layer (10) is rigid relative to the other layers (11, 12, 13, 14) included in the assembly (9a, 9b) which are flexible. 13. Watch (1) comprising a dial (2a, 2b) according to any one of the preceding claims. 14. Watch (1) according to the preceding claim, characterized in that it comprises a mechanical or electromechanical or electronic watch movement.