ELECTRONIC CLOCK WITH SOLAR CELL

Description

technical field

[0001] The present invention relates to an electronic watch equipped with a photovoltaic cell. State of the art

[0002] Electronic watches with photovoltaic cells are well-known. The cell is mounted beneath the watch crystal, allowing it to capture solar energy while the watch is worn. This solar energy is converted into electrical energy to power the watch's electrical and electronic components, such as a motor that moves the hands and / or a rechargeable battery.

[0003] The photovoltaic cells used in certain types of high-end watches consist of a fragile substrate, often made of glass, which supports layers of semiconductor material. The substrate must withstand the stresses induced during assembly as well as the watch's lifespan. Shock resistance is particularly important.

[0004] Documents JPH11118952 and JP4275804 describe watches in which a photovoltaic cell is held in contact with a watch movement module by an annular lateral support. Since the lateral support is limited to the periphery of the cell, the risk of decoupling between the cell and the movement module during impacts remains significant. Furthermore, the lateral support is a component that complicates the watch's construction and can make disassembly difficult. Document JPH08166469 describes the fabrication of photovoltaic cell layers on a metal substrate to create a watch dial with the cell integrated into the dial. However, this solution still requires lateral mounting of the dial. Moreover, this solution is not applicable in the most common scenario, where a prefabricated photovoltaic cell is integrated during the watch movement assembly process.

[0005] US 4,666,313 A describes an electronic watch with a photovoltaic cell comprising a support plate bearing the cells on its front face and a mechanism fixed to its back face. The watch is secured by screws passing through the periphery of the mechanism and engaging in threaded sockets mounted on the plate. US 4,276,629 A relates to a solar watch designed for a thin and shock-resistant construction. The watch comprises a base plate, a flexible insulating sheet bearing the cells, and a module mounted underneath. A peripheral reinforcement (dial ring) is provided to limit deformation. The architecture is multilayered and geared towards compactness and mechanical strength. Summary of the invention

[0006] The present invention aims to provide an electronic watch with a photovoltaic cell that does not suffer from the drawbacks described above. This objective is achieved by a watch movement and a watch according to the attached claims.

[0007] A clockwork movement according to the invention is defined in claim 1. Preferred embodiments are defined in claims 2 to 7.

[0008] Other features and advantages of the present invention will become apparent from the following description of preferred embodiments, presented by way of non-limiting example with reference to the accompanying drawings. Brief description of the figures

[0009] There figure 1 represents a clockwork mechanism for an electronic watch with a photovoltaic cell according to one embodiment of the invention. The figures 2a to 2krepresent different stages of the method of assembling a movement and a watch according to one embodiment of the invention. Detailed description of embodiments of the invention

[0010] Movement 1 is represented at the figure 1 includes a photovoltaic cell 2 mounted below the hands 3 of the watch to be assembled, and fixed to the upper surface of a rigid support plate 4. The movement 1 further includes a digital display 5. The figure 2arepresents the support plate 4 according to this particular embodiment. Characteristically for the invention, the plate is provided with a plurality of nuts 6 which are secured to the lower surface of the plate 4, i.e., the surface opposite the surface to which the photovoltaic cell 2 will be attached. The nuts are preferably cylindrical nuts. The nuts 6 can be fixed to the plate 4 by welding or bonding, depending on the material of the plate 4. This material can be a metallic material. The specific plate 4 shown in the figure 2aIt is equipped with a window 7 for the digital display, a central hole 8 for the passage of the hands' rotation axes, and several openings and notches. The round notches 10 will serve as mounting points for the movement in a case (see later), and the openings 11 will receive the screw heads of the motor module (also see later). The rectangular notches 12 will serve as passages for electrical connection strips and / or as alignment marks for the movement in a watch case.

[0011] To the figure 2bThe photovoltaic cell 2 is shown before being assembled to the rigid plate 4. The cell comprises a glass substrate with thin films of semiconductor material (not shown). The substrate is bonded by an electroconductive adhesive to a flexible printed circuit board (FPC), which includes a connector 13, for example, via a flexible electrical connection 25. In this context, the substrate and FPC together are considered to be the photovoltaic cell 2. The cell 2 includes a central hole 15 for the passage of the needle rotation shafts, as well as a window 16 for the digital display.

[0012] As illustrated in the figure 2cCell 2 is bonded to the upper surface of the support plate 4, preferably by means of a double-sided adhesive layer laminated to the plate 4. Cell 2 is centered on the plate 4 so that the central openings 8 and 15, as well as the windows 7 and 16, are aligned with each other. The flexible connection 25 with the connector 13 is positioned at the height of one of the rectangular notches 12 provided on the periphery of the plate 4.

[0013] There figure 2d represents the mounting of the digital screen 5 in the opening created by the windows 7 and 16. The screen 5 can be made as an assembly of known electronic components, such as a MIP (Memory in Pixel) layer and a backlight layer, equipped with a connector 17.

[0014] There figure 2e represents the assembly of motor module 14 of the movement of the figure 1A second rigid support plate 18 is provided, which has the same perimeter as the photovoltaic cell support plate 4. Like the support plate 4, the second plate 18 can be a metal plate. An electric motor 19, equipped with the rotation axes 20 of the needles 3, is centrally attached to the second support plate 18 by screws 21, with a first portion 22a of a printed circuit board (PCB) 22 mounted between the motor 19 and the second plate 18. The PCB 22 includes a second portion 22b that can be folded over the first portion 22a mounted between the motor 19 and the second plate 18.The second plate 18 and the first part 22a of the PCB are provided with aligned openings 23 (which correspond to a single opening when the module is assembled), which correspond respectively to the nuts 6 of the first support plate 4, so that the flat surface of the second plate 18 is positioned in contact with the lower surface of the first support plate 4 on which the nuts 6 are mounted. In other words, the openings 23 are positioned and dimensioned such that the nuts 6 pass through these openings 23, so that the two plates 4 and 18 can be positioned back-to-back, see [reference]. figure 2fThe heads of the screws 21 will fit into the openings 11 provided in the support plate 4. The second plate 18 has a central hole 24 aligned with the central holes 8 and 15 in cell 2 and in the first support plate 4, when the two plates 4 and 18 are assembled. The aligned central holes allow access to the rotation shafts 20 of the motor 19, on the upper side of the assembly.

[0015] The screen 5 connector 17 is plugged into a socket provided in the first part 22a of the PCB 22. A spacer 30 is then positioned on said first part 22a of the PCB ( Fig. 2g). The spacer 30 is also provided with openings 31 which allow the passage of the nuts 6, as well as a cavity 32 sized to receive the motor 19, so that the spacer 30 can be installed in contact with the first part 22a of the PCB. The spacer 30 and the motor module 14 are then secured to the support plate 4 by screws 33 screwed into the nuts 6. The folding part 22b of the PCB is now bent to cover the spacer 30 and fixed by screws 34 ( Fig. 2h ). The photovoltaic cell connector 13 is plugged into a socket on PCB 22. After the hands 3 are mounted, the movement assembly 1 is shown in the figure 1 is complete.

[0016] This movement is then installed in the case 35 of a watch, see figures 2i And 2jThe case 35 includes the watch crown 36 connected to a connector 37 which will be plugged into a socket on the PCB 22. The assembly of the two plates 4 and 18 is attached to the case 35 by screws 38 and flanges 39, the screws 38 being screwed into the round notches 10 at the periphery of the plates 4 and 18. The watch assembly is completed by the mounting of an indexing ring 40 and a bezel 41 ( figure 2k ).

[0017] The invention is not limited to the embodiment shown in the figures. For example, the invention also covers embodiments that do not include a digital display 5. The photovoltaic cell 2, the motor 19, the PCB 22, and the case 34 can be implemented in any one of several embodiments known in the prior art. The motor module is only one example of an electrical module usable in a watch according to the invention. Other modules usable for a digital watch (without hands) according to the invention do not include a motor, but only microelectronic components. For the electrical module 14 to be usable in the invention, it is sufficient that it include a flat surface to be installed against the underside of the support plate 4. According to the embodiment shown in the figures, the 'flat surface' is the surface of the plate 18 that is opposite the surface to which the motor 19 is attached.Furthermore, and in general, the electrical module must be provided with openings which allow the passage of the nuts 6. In the case of the embodiment shown in the figures, the openings 23 pass through the second plate 18 and the first part of the PCB 22.

[0018] In any embodiment of the invention, the nuts 6 allow a clockwork movement to be assembled to a photovoltaic cell without requiring lateral support. The assembly is easily removed by unscrewing the screws 33. In preferred embodiments, and as is also the case in the embodiment shown in the figures, the nuts 6 are positioned in a specific manner on the surface of the support plate 4. A first group of nuts is located near the periphery of the plate 4, and a second group is located more centrally on the plate, near the motor 19 when the motor module 14 is assembled to the support plate 4. The central nuts improve the stability of the assembly comprising the support plate 4 and the motor module 14, and prevent these components from separating in the event of impacts.This also reduces the risk of the hands coming loose, which allows a central hole to be machined in the cell closest to the diameter of the hour hand barrel to optimize the aesthetics of the watch face.

Claims

1. Electronic watch movement (1) comprising a photovoltaic cell (2) and an electrical module (14), said module comprising a flat surface, and in which: - the movement further comprises a first rigid support plate (4), - the photovoltaic cell (2) is fixed to the upper surface of the support plate (4), - the support plate (4) is provided with a plurality of nuts (6) mounted on the lower surface thereof, - the flat surface of the electrical module (14) is mounted in contact with said lower surface of the support plate (4), the electrical module being provided with a plurality of openings (23) whose position and dimensions correspond to those of the nuts (6), so that the nuts (6) pass through the openings (23), - the electrical module (14) and the support plate (4) are secured to each other by a plurality of screws (33), screwed into the nuts (6), - the electrical module (14) comprises a second support plate (18) provided with said openings (23), and wherein the flat surface of the electrical module (14) is one of the surfaces of the second support plate (18) which is positioned back-to-back with respect to the first support plate (4), a first group of nuts (6) being positioned in proximity to the periphery of the support plate (4), and a second group of nuts being positioned more centrally with respect to the periphery than the first group and the first and second support plates (4, 18) having identical circumferences.

2. A timepiece movement according claim 1 claims, comprising a spacer (30) positioned on the second support plate (18) on the opposite side to the photovoltaic cell (2), and also provided with openings (31) which allow the passage of the nuts (6), so that the spacer (30) and the two support plates (4, 18) are secured to each other by the screws (33) screwed into the nuts (6).

3. A timepiece movement according to claim 1 or 2, comprising hands (3), and wherein the electrical module (14) includes an electrical motor (19) mounted on the second support plate (18) on the other side of the first support plate (4), the motor comprising the rotating hand arbors (20) which are accessible through central holes (8, 15, 24) aligned with each other, said holes being respectively provided in the photovoltaic cell (2) and in the two support plates (4, 18).

4. A timepiece movement according to claim 3, comprising a spacer (30) provided with a cavity (32) which can accommodate the motor (19).

5. A timepiece movement according to any of the preceding claims, comprising a digital screen (5) and wherein the first support plate (4) is provided with a window (7) adapted to the dimensions of the screen (5).

6. An electronic watch according to any of the preceding claims, wherein the photovoltaic cell (2) includes a substrate made of glass or another fragile material.

7. An electronic watch comprising a case middle (35) in which a movement (1) according to any of the preceding claims is installed.