CLOCK WITH A LIGHT SENSOR AND ANTENNA

Description

Technical field of the invention

[0001] The invention relates to the field of watches equipped with a light sensor, formed of at least one photovoltaic cell, to power an electronic device of the watch, and an antenna for communication with at least one system or device external to the watch.

[0002] In particular, the watch according to the invention comprises a case incorporating the watch movement and an analog time display, this case being formed from a metallic material. Technological background

[0003] Document JP 2019 / 060847 describes an electronic watch comprising a case having an upper opening, a crystal closing the upper opening of the case, a movement, an analog display driven by the movement, and an assembly arranged on the movement and formed by a light sensor (also called a 'solar sensor') and an upper dial for the analog display. The light sensor is formed by a plurality of photovoltaic cells. As shown in Figure 1, attached to this description, which represents an embodiment described in document JP, the assembly 2 comprises a film 4, a light sensor 14 arranged on this film, which therefore forms a support for the light sensor, and an upper dial 16, separate from the light sensor, which lets light pass for the light sensor so that this light sensor is visible to a user observing the assembly 2 through the watch crystal. The upper dial 16 carries in particular a graduation for displaying the time. The photovoltaic cells of the light sensor are each formed by the stacking of a metal electrode 6, a layer of semiconductor material 8, a transparent electrode 10 arranged above the semiconductor layer and a protective layer 12. The watch further comprises an antenna 20 arranged to communicate through the crystal of this watch with a communication device external to the watch.

[0004] The assembly 2 has a first part 22, in which the metal electrodes and the transparent electrodes are arranged, and a second part 24 which is, in projection in a general plane of the assembly (perpendicular to the central axis of the hole 18 provided for the passage of the axes of the analog time display), distinct from the first part 22 and which covers the antenna 20. The layer of semi-conductor material 8 extends in the first part 22 and also in the second part 24 of the assembly 2, and this layer partly determines the color of the assembly 2 for a user observing this assembly through the glass.In the absence of the addition of a non-conductive layer 26, which is provided as a solution in the Japanese document described here, the presence of upper transparent electrodes poses a visual problem since it causes a variation in color, in particular a variation in hue due to a variation in light reflection, between the first portion 22 and the second portion 24. To solve this problem, it is provided to add in the second portion 24 a non-conductive layer 26 which is selected to adjust the transmission of light, and thus the reflection at the interface between this layer and the protective layer 12, so that this transmission corresponds substantially to that of the transparent electrode 10.

[0005] Such a solution requires the deposition of an additional layer and it is difficult, or even almost impossible, to obtain exactly the same shade for the two parts 22 and 24. Then, the junction line between the additional layer 26 and the upper transparent electrodes 10 is visible. In addition, since the light sensor 14 comprises a plurality of photovoltaic cells whose upper transparent electrodes 10 define separate sectors, as shown in the figures of the JP document in question, the areas between the transparent electrodes remain visible, so that a user of the watch, observing the dial, distinguishes the photovoltaic cells due to a difference in shade between the transparent upper electrodes 10 and the separation areas between them which do not have the conductive material forming the transparent electrodes.Thus, the fact that a light sensor is arranged under the dial 16 remains visible in the embodiment described here. This fact always creates a certain aesthetic problem, so that the solution envisaged in the Japanese document is partial and therefore does not entirely resolve the aesthetic problem linked to the presence of a light sensor under the dial. Indeed, in particular for watches with an analog time display, it is generally appreciated that the dial has a uniform color (exceptions made in particular for useful or decorative prints). A variation in color between two regions of the dial linked to the arrangement of various technical parts often gives a 'low-end' appearance to the watch. In addition, in particular for classic watches, it may be desired to mask the presence of photovoltaic cells as best as possible. Summary of the invention

[0006] The present invention aims to solve the aforementioned aesthetic problem for a watch incorporating a light sensor under an analog display, which is covered by a crystal (also called a glass), and comprising a communication antenna which must be able to communicate with the outside through the crystal. A main objective of the invention is to provide such a watch in which the presence of at least one photovoltaic cell at the dial cannot be detected through the crystal by a user of the watch. The invention also aims to provide a watch with a classic appearance with a dial which appears opaque, of a relatively dark shade.

[0007] To this end, the present invention relates to a watch comprising a case having an upper opening, a crystal closing this upper opening, a movement, an analog display driven by the movement, an assembly located between the movement and the analog display and comprising a light sensor, which is formed by a wafer or layer of semiconductor material, at least one negative electrode and at least one positive electrode. The watch incorporates an antenna arranged to be able to communicate through the crystal with a communication device external to the watch. Said assembly has a first part, in which are entirely arranged said at least one positive electrode and said at least one negative electrode, and a second part without electrodes which is separated from the first part and of which a projection in a general plane of said assembly includes a projection of the antenna in this general plane.The wafer or layer of semiconductor material extends, parallel to the general plane, in the first part and the second part of said assembly. Said at least one negative electrode and said at least one positive electrode are all located below the wafer or layer of semiconductor material.

[0008] Thus, the wafer or layer of semiconductor material, in particular silicon, extends into the first region of the aforementioned assembly, where the photovoltaic light sensor is located, and into the second region of this assembly which includes or covers the antenna. In addition, all the electrodes are arranged below the wafer or layer of semiconductor material. Thanks to this characteristic, the first region and the second region of the assembly can have exactly the same color, for a user observing the assembly through the glass, and not have a junction line or transition zone between these two regions. In addition, since no electrode is arranged on the semiconductor wafer or layer, it is not possible to visually detect the presence of a light sensor and in particular to discern the structure of such a sensor comprising several photovoltaic cells.Preferably, the wafer or layer of semiconductor material extends throughout the first part and the second part of said assembly. In an advantageous variant making it possible to obtain a dial entirely of the same color and having a uniform appearance, the wafer or layer of semiconductor material extends throughout the visible part of the assembly for a user observing this assembly through the crystal. Then, preferably, the wafer or layer of semiconductor material has an upper surface having a uniform specific treatment, in particular a texturing or micro-structuring. In addition, one or more additional layers provided above the wafer or layer of semiconductor material are advantageously homogeneous and cover the entire assembly.Finally, the upper surface of the assembly may have, at least in certain areas, a specific finish and in particular the same finish over the entire upper surface. By 'same color' we mean the basic color / shade of the dial which is homogeneous, therefore exceptions are made in particular for useful or decorative prints, appliques on the dial or elements inserted into the dial.

[0009] The invention also relates to a dial, for a watch having an analog display, comprising a light sensor which is formed by a wafer or layer of semiconductor material, at least one negative electrode and at least one positive electrode, this dial having a first part, in which said at least one negative electrode and said at least one positive electrode are entirely arranged, and a second part which is, in projection in a general plane of the dial, separate from the first part and which is provided for the passage of electromagnetic signals through the dial. The wafer or layer of semiconductor material extends parallel to said general plane in the first part and the second part of the dial, said at least one negative electrode and said at least one positive electrode all being located below the wafer or layer of semiconductor material.

[0010] According to an advantageous embodiment, the second part of the dial comprises the antenna, which is arranged below the wafer or layer of semiconductor material, this antenna preferably being deposited on the same layer as the electrodes of the light sensor. Brief description of the figures

[0011] The invention will be described below in more detail with the aid of the appended drawings, given as non-limiting examples, in which: there Figure 1 , already described, represents an assembly, according to the prior art, which comprises a dial for a watch and a photovoltaic light sensor, as well as an antenna arranged in the watch under the assembly represented; the Figure 2represents, in a simplified manner, a first embodiment of a watch according to the invention comprising a first assembly according to the invention and an antenna, the first assembly forming a dial which incorporates a photovoltaic light sensor; the Figure 3 is a sectional view of a second assembly according to the invention intended to be incorporated into a second embodiment of a watch according to the invention; and the Figure 4 is a sectional view of a particular variant of the second set of the Figure 3 , according to a section plane at the level of the electrodes of the photovoltaic light sensor. Detailed description of the invention

[0012] In reference to the Figure 2 , a first embodiment of a watch according to the invention will be described below.

[0013] The watch 30 comprises a case 32 having an upper opening 33, a crystal 34 closing the upper opening, a movement 36, an analog display 38 driven by the movement, and an assembly 40 which is generally located between the movement and the analog display and which here advantageously itself forms the dial of the watch associated with the analog display, no cover plate for the assembly 40 being provided between this assembly and the analog display. The assembly 40 comprises a light sensor 42 comprising at least one photovoltaic cell and which is formed by a wafer or layer of semiconductor material 44 (also called a semiconductor wafer or layer), at least one negative electrode 46 and at least one positive electrode 48 all located below the semiconductor wafer or layer.In the variants of the invention shown, the assembly comprises or is fixed to a support 50 (depending on whether this support is considered to be part of the assembly or not), in particular by gluing. The wafer or layer of semiconductor material 44 is preferably a wafer or layer of silicon (Si).

[0014] In the first embodiment, the semiconductor wafer or layer 44 has a lower region 45 which is doped to form areas facilitating the conduction of electrical charges towards said at least one negative electrode and said at least one positive electrode with which they are associated (a negatively doped area, called n or N type, is connected to a negative electrode, while a positively doped area, called p or P type, is connected to a positive electrode). By 'doped region / zone' is meant a region / zone having an electrical conduction which is not very weak, or even almost zero (as is generally the case for low n, N dopings or low p, P dopings). Thus, a doped area is, according to the usual notations in the field of semiconductors, either an N+ area or a P+ area, or an N++ area or a P++ area.To clearly indicate that an area is considered sufficiently doped to exhibit significant electrical conduction, the term 'conductive doped area' is used. In the first embodiment, the wafer or layer of semiconductor material 44 has conductive doped areas over its entire lower portion.

[0015] The watch further comprises an antenna 20 arranged to be able to communicate through the crystal 34 with a communication device (not shown) which is external to the watch. The assembly 40 has a first part 52, in which said at least one negative electrode 46 and said at least one positive electrode 48 are entirely arranged and in which the light sensor 42 is therefore arranged, and a second part 54 without electrodes which is separated from the first part and of which a projection in the general plane 56 of said assembly (this general plane being perpendicular to the axis of rotation 58 of the hands forming the analog display 38) includes a projection of the antenna 20 in this general plane.Thus, the light sensor does not prevent the antenna from communicating with a communication device whose electromagnetic signals enter the watch through the crystal 34, because the antenna and the light sensor are arranged, in projection in the general plane of the assembly 40, in separate regions. So that a user of the watch cannot distinguish the first part and the second part of the assembly 40 forming the dial, the wafer or layer of semiconductor material 44 extends, parallel to the general plane 56, in the first part 52 of the assembly 40, to form the light sensor 42, and also in the second part 54 of this assembly. In addition, according to the invention, all the electrodes of the light sensor are located below the semiconductor wafer or layer 44. Thus, as can be seen in . Figure 2 (and also to the Figure 3concerning the second embodiment), the arrangement of the light sensor 42 does not generate any particular treatment of the upper surface of the wafer or layer of semiconductor material 44 and no deposition of material on this upper surface, which is uniform and has a homogeneous opaque appearance for an observer. This observer cannot therefore distinguish the presence of the light sensor by the presence of a structured upper layer, in particular transparent upper electrodes, as in the prior art.

[0016] The semiconductor wafer or layer extends continuously from the first part 52 to the second part 54 and it forms a single semiconductor wafer or layer which extends at least partially in these first and second parts or, preferably, over the entire region of the assembly 40 which is visible to a user of the watch observing this assembly, forming a dial, through the crystal 34. This last preferred variant makes it possible to obtain a dial with a homogeneous color and presenting the same uniform appearance for the user observing this assembly through the crystal. In particular, the wafer or layer of semiconductor material extends throughout the first part 52 and the second part 54 of the assembly 40, that is to say throughout the region of the light sensor 42 and the entire region superimposed on the antenna 20.

[0017] According to an advantageous variant, the assembly 40 further comprises at least one layer 60 which is transparent, semi-transparent or translucent and which is arranged above the semiconductor wafer or layer 44. Preferably, the layer 60 is homogeneous and extends over the entire visible part of the assembly 40, forming the dial of the watch 30, for a user observing this assembly through the crystal 34. In particular, this layer 60 forms an upper layer of the assembly 40 and has an upper surface which is uniform, at least in the region visible to a user observing this assembly through the crystal. In particular, the layer 60 is arranged so as to completely cover the semiconductor wafer or layer. Thus, this layer 60 does not alter the perfect homogeneity of color and the uniformity of appearance of the assembly 40 forming here the dial of the watch.The layer 60 is advantageously transparent, possibly with a slight coloring, and it determines, together with the semiconductor wafer or layer and any layers deposited on the latter, the color of the first part 52 and of the second part 54 of the assembly 40 for a user observing this assembly through the glass 34, preferably of the entire region of this assembly visible to this user. The transparent, semi-transparent or translucent layer 60 makes the color of the semiconductor wafer or layer darker, in particular it gives the assembly 40 an anthracite, midnight blue or black color for a user observing the assembly through the glass. Thus, the layer 60 darkens the color of the assembly 40 and gives it a deep color with the most beautiful effect.

[0018] In addition, the upper layer 60 determines the state of the upper surface of the assembly 40. Indeed, the upper surface of the transparent, semi-transparent or translucent layer 60 may have a finish giving, at least in areas, a matte, brushed, satin or glossy appearance to the assembly. In a variant, this upper surface has a full linear or radial brushing. In particular, the upper layer 60 of the assembly 40 is a layer of transparent varnish which is applied to the semiconductor wafer or layer 44. In addition, the assembly 40 may comprise at least one additional layer above the semiconductor wafer or layer. Such an additional layer may be a film forming a filter, an anti-reflection layer or a light diffusion layer in transmission.

[0019] In a particular variant suitable for the arrangement of the antenna in the watch according to the invention, the case 32 is formed at least in major part by one or more metallic material(s). In a conventional variant, the external parts of the case 32 are entirely metallic.

[0020] In reference to the Figures 3 and 4 , a second embodiment of a dial assembly according to the invention will be described below. Certain elements already described in detail above and possible variants will not be described again for the second embodiment, the description focusing firstly on the differences and particularities of this second embodiment.

[0021] As in the first embodiment, this second embodiment is advantageously characterized by the fact that the positive electrodes and the negative electrodes are arranged under the wafer or layer of semiconductor material 44A. This second embodiment is essentially distinguished from the first embodiment by the fact that the antenna is included in the assembly or supported by the latter.

[0022] To the Figure 3An assembly 70 according to the invention is shown which forms a dial for a watch with an analog display and which comprises a light sensor 72 formed of at least one photovoltaic cell. Generally, the light sensor 72 is formed by a wafer or layer of semiconductor material 44A, negative electrodes 78 and positive electrodes 79. The assembly 70 has a first part 52A, in which the negative electrodes and the positive electrodes are entirely arranged, and a second part 54A which is, in projection in a general plane 56 of the assembly, separated from the first part. The second part is provided for the passage of electromagnetic signals coming from a communication device or generated by the antenna 80.The wafer or layer of semiconductor material 44A (the semiconductor wafer or layer) extends, parallel to said general plane, in the first part 52A and the second part 54A of the assembly 70 which is a dial. The second part 54A of the assembly 70 comprises or supports, on a lower side of this assembly, an antenna 80. To avoid impairing the proper functioning of the antenna 80, the wafer or layer of semiconductor material 44A does not here have conductive doped zones in the second part of said assembly. It will be noted that the wafer or layer of semiconductor material 44A may be lightly doped in part or completely in the second part 54A of the assembly 70.

[0023] The antenna 80 is located below the wafer or layer of semiconductor material, so as to be invisible from the side of the upper surface 62 of the assembly, which is the visible surface of the dial formed by this assembly 70 once the latter is incorporated into a watch case to form a watch according to the invention.

[0024] In the advantageous variant shown in the Figure 3 , the second part 54A of the assembly 70 comprises the antenna 80, which is arranged below the semiconductor wafer or layer 44A. In particular, the antenna 80 is deposited on the same layer 82 as the electrodes 78 and 79 of the light sensor. The lower layer 82 is a passivation layer useful for the light sensor 72. In the variant shown in Figure 3, there are a plurality of negative electrodes 78 and a plurality of positive electrodes 79 arranged alternately, each positive electrode being arranged between two negative electrodes. The plurality of negative electrodes 78 and the plurality of positive electrodes 79 are all deposited lower on the passivation layer 82, which lower covers the semiconductor wafer or layer 44A, and are connected by openings provided in the passivation layer 82 respectively to a plurality of lower N+ doped zones 74 and to a plurality of lower P+ doped zones 76, these doped zones 74, 76 therefore being conductive. In a particular variant, the antenna 80 is formed by the same material as the negative electrodes and the positive electrodes.

[0025] Typically, the semiconductor wafer or layer is conductively doped in various regions of the first part of the assembly. However, the semiconductor wafer or layer is not conductively doped in the second part 54A of the assembly. As previously indicated, 'conductively doped' indicates 'doped so as to exhibit significant electrical conduction' and consequently 'conductively undoped' means 'undoped so as to exhibit significant electrical conduction' or equivalently 'without doping or doped so as to exhibit insignificant, i.e. very low, electrical conduction'. Thus, in the second region of the assembly, the semiconductor wafer or layer 44 may, in a variant, be lightly doped (i.e. n, N doped or p, P doped according to the usual terminology). What matters is that the semiconductor wafer or layer does not create a magnetic shield for the antenna through doping.In other words, it is avoided to significantly disrupt a transmission of electromagnetic signals between the antenna and an external communication device located on the side of the upper surface of the assembly 70 and with which it is intended that a watch, incorporating this assembly, can communicate through the upper glass of the watch, or to cause a significant increase in the intensity of such signals to ensure correct communication.

[0026] In a main variant, the wafer or layer of semiconductor material 44A extends throughout the first part 52A and the second part 54A of the assembly 70.

[0027] In a preferred variant, the wafer or layer of semiconductor material extends in projection over the entire upper surface 62 of the assembly 70.

[0028] Preferably, the wafer or layer of semiconductor material has a texturing (micro-structuring) over its entire upper surface and at least one anti-reflective layer 84 is deposited on the wafer or layer of semiconductor material, so as to cover it entirely. The anti-reflective layer is deposited uniformly on the wafer or layer of semiconductor material. The assembly 70 may further comprise a light diffusion layer. Preferably, all the layers deposited above the semiconductor wafer or layer 44A are deposited uniformly over the entirety of this semiconductor wafer or layer. An assembly 70 is obtained having, on the side of its upper surface 62, a perfectly homogeneous color and a perfectly uniform appearance.However, for aesthetic purposes or for the dial to have a given pattern, other than that of a photovoltaic cell or an antenna, for example a logo, the treatment of at least one upper layer may not be uniform, but deliberately differentiated.

[0029] The assembly 70 further comprises, as in the first embodiment, an upper layer 60 which is transparent or translucent and which determines, together with the wafer or layer of semiconductor material and the antireflection layer 84, the color of said first and second parts of the assembly on the side of the upper surface 62 of the assembly. In addition, it determines the state of this upper surface. Preferably, the upper layer 60 is transparent and uniformly covers the entire upper surface 62 of the assembly 70.

[0030] Finally, the assembly 70 is glued to a support 50 by means of a layer of glue 86. As already indicated, it can be considered that this support 50 is part of the assembly 70, or not. With the support 50, the assembly defines a module which forms a sundial, that is to say provided with at least one photovoltaic cell, and which furthermore incorporates an antenna.

[0031] There Figure 4 shows in section an assembly 70A which is a variant of the second embodiment. The section is parallel to the general plane of the assembly 70A at the level of the electrodes of its light sensor. If we consider the support 50 and the layer of glue 86 not included in the assembly or in the case where such a support is not provided, then the Figure 4is a bottom view of the assembly. This variant is particular in the arrangement of the plurality of negative electrodes 78A and the plurality of positive electrodes 79A, this arrangement making it possible to occupy in an optimized manner a semi-circular part or a truncated circle part of a disc having a hole 18 in its center for the passage of the axes of an analog display. The particular arrangement of the negative and positive electrodes, nested within each other, further makes it possible to have the negative contact pad 88, to which the negative electrodes 78A are connected, and the positive contact pad 89, to which the positive electrodes 79A are connected, one next to the other in the same radial zone of the assembly 70A, and thus to have two adjacent contact pads which are close to each other, which facilitates the electrical connection to an electrical connector provided for the light sensor.

[0032] The plurality of negative electrodes 78A and the plurality of positive electrodes 79A, the two contact pads 88 and 89 and the antenna 80A are deposited below the passivation layer 82 described above. The question of whether it is a plurality of negative electrodes and a plurality of positive electrodes or a single negative electrode and a single positive electrode each having a plurality of elongated arms, given that all the arms of the same polarity are connected to the same contact pad is a question of definition which has no consequence for the present invention.

[0033] The antenna 80A is provided for high-frequency communication, this antenna being formed by a single U-shaped track whose two ends are connected respectively to two contact pads 90 and 91 which are also deposited on the passivation layer 82, which defines in particular a rear mirror for the light sensor. The passivation layer extends over the entire semiconductor wafer or layer, which extends, in projection in the general plane of the assembly 70A, over this entire assembly. The light sensor occupies a first part 52A of the assembly and the antenna occupies a second part 54A of this assembly, distinct from the first part, these two parts constituting the entire assembly 70A. Thus, by 'separate', we also understand a case where the two parts are contiguous.

[0034] In another variant not shown, the second part of the assembly supports the antenna (a module forming this antenna) on a lower side of this assembly, this antenna being fixed to the assembly for example by gluing.

[0035] Finally, it will be noted that the first part and the second part may have different shapes and that the electrodes may be arranged differently. For example, the light sensor may be annular with the antenna arranged in the center. In this case, the first part of the assembly forms an annular structure and the second part of this assembly forms a central disc with a circular hole in its center. In another variant, the second part may consist of a substantially rectangular or square portion which extends radially from the periphery of the assembly forming the dial, the first part of the assembly forming the part complementary to this radial portion.

Claims

1. Watch (30) comprising a case (32) having a top opening (33), a crystal (34) closing this top opening, a movement (36), an analog display (38) driven by the movement, an assembly (40; 70, 70A) located between the movement and the analog display and comprising a light sensor (42; 72) which is formed by a semiconductor material wafer or layer (44; 44A), at least one negative electrode (46; 78, 78A) and at least one positive electrode (48; 79, 79A); the watch comprising an antenna (20; 80, 80A) arranged to be able to communicate through the crystal with a communication device external to the watch; said assembly having a first portion (52; 52A), in which are arranged entirely said at least one positive electrode and said at least one negative electrode, and a second portion (54; 54A) without electrode which is separated from the first portion and a projection of which in a general plane (56) of said assembly includes a projection of the antenna in this general plane; the semiconductor material wafer or layer (44; 44A) extending, parallel to the general plane, into the first portion and the second portion of said assembly; characterised in that said at least one negative electrode (46; 78, 78A) and said at least one positive electrode (48; 79, 79A) are all located below the semiconductor material wafer or layer (44; 44A).

2. Watch according to claim 1, characterised in that the semiconductor material wafer or layer (44A) has no conductive doped areas in the second portion (54A) of said assembly.

3. Watch according to claim 1 or 2, characterised in that the semiconductor material wafer or layer (44; 44A) extends throughout the first portion and the second portion of said assembly.

4. Watch according to claim 1 or 2, characterised in that the semiconductor material wafer or layer (44; 44A) extends throughout the visible portion of said assembly for a user observing said assembly through the crystal (34).

5. Watch according to any one of claims 1 to 3, characterised in that the semiconductor material wafer or layer is textured over its entire upper surface; and in that an anti-reflective layer (84) is deposited above this upper surface.

6. Watch according to any one of claims 1 to 4, characterised in that said assembly (40; 70) comprises a transparent, semi-transparent or translucent layer (60) which is arranged above the semiconductor material wafer or layer, which forms an upper layer of the assembly and which darkens the colour of this assembly, giving it in particular an anthracite, midnight blue or near-black colour.

7. Watch according to claim 6, characterised in that the upper surface of the transparent, semi-transparent or translucent layer has a finish giving, at least in some areas, a matt, brushed, satin or glossy appearance to said assembly.

8. Watch according to any one of claims 1 to 7, characterised in that said assembly itself forms a dial for the analog display, no cover plate of said assembly being provided between the assembly and the analog display.

9. Watch according to any one of claims 1 to 8, characterised in that the antenna is supported by said assembly on a lower side of this assembly.

10. Watch according to any one of claims 1 to 8, characterised in that the antenna (80, 80A) is deposited, on a lower side of the semiconductor material wafer or layer (44; 44A), on a same layer as said at least one positive electrode and said at least one negative electrode.

11. Watch according to any one of claims 1 to 10, characterised in that said case (32) is formed at least for the most part by one or more metallic materials.

12. Dial (40; 70, 70A), for a watch having an analog display, comprising a light sensor (42; 72) which is formed by a semiconductor material wafer or layer (44; 44A), at least one negative electrode (46; 78, 78A) and at least one positive electrode (48; 79, 79A), this dial has a first portion (52; 52A), in which said at least one negative electrode and said at least one positive electrode are arranged in their entirety, and a second portion (54, 54A) which is, in projection in a general plane (56) of the dial, separated from the first portion and which is provided for the passage of electromagnetic signals through the dial, the semiconductor material wafer or layer extending parallel to said general plane in the first portion and the second portion of the dial, characterised in that said at least one negative electrode and said at least one positive electrode are all located below the semiconductor material wafer or layer.

13. Dial (70, 70A) according to claim 12, characterised in that the semiconductor material wafer or layer (44A) has no conductive doped areas in the second portion (54A) of the dial.

14. Dial according to claim 12, characterised in that the second portion (54A) of the dial comprises an antenna (80, 80A), which is arranged below the semiconductor material wafer or layer (44A).

15. Dial according to claim 14, characterised in that the antenna (80, 80A) is deposited on the same layer (82) as said at least one negative electrode (78, 78A) and said at least one positive electrode (79, 79A).

16. Dial according to claim 15, characterised in that the antenna is formed by the same material as said at least one negative electrode (78, 78A) and said at least one positive electrode (79, 79A).

17. Dial according to any one of claims 12 to 16, characterised in that the semiconductor material wafer or layer (44A) extends in said general plane over the entire dial.

18. Dial according to any one of claims 12 to 17, characterised in that the semiconductor material wafer or layer has a texturing over its entire upper surface.

19. Dial according to any one of claims 12 to 18, characterised in that an anti-reflective layer (84) is uniformly deposited on the semiconductor material wafer or layer (44A).

20. Dial according to any one of claims 12 to 19, characterised in that it comprises at least one transparent, semi-transparent or translucent layer (60) which is arranged above the semiconductor material wafer or layer (44A) so as to cover it entirely, and which darkens the colour of the dial, in particular anthracite, midnight blue or near-black.

21. Dial according to claim 20, characterised in that an upper surface (62) of the transparent, semi-transparent or translucent layer (60) has a finish giving, at least in some areas, a matt, brushed, satin or glossy appearance to the dial.