CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to European Patent Application No. 19206954.0 filed on Nov. 4, 2019, the entire disclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an electronic watch provided with a photovoltaic cell.

STATE OF THE ART

Electronic watches with a photovoltaic cell are well known. The cell is mounted under the watch crystal, so that the cell can capture photovoltaic energy while the watch is worn. The solar energy is converted into electrical energy to power the electrical and electronic watch components, such as a motor for moving hands and/or a rechargeable battery.

The photovoltaic cells used in certain types of high-end watches consist of a fragile substrate, often made of glass, which carries layers of semiconductor material. The substrate must withstand the stresses induced during assembly and over the life cycle of the watch. Shock resistance is particularly important.

Japanese Patent Nos. JPH11118952 and JP427580 disclose watches wherein a photovoltaic cell is held in contact with a motor module of the watch by an annular lateral support. As the lateral support is limited to the periphery of the cell, the risk of the cell and the motor module coming apart during shocks remains significant. Further, the lateral support is a component which complicates the construction of the watch, and which can make disassembly difficult. Japanese Patent No JPH08166469 describes the fabrication of layers of a photovoltaic cell on a metal substrate to make a watch dial with the cell integrated in the dial. However, this solution still requires means to secure the dial laterally. Moreover, this solution is not suitable for the most common case in which a prefabricated photovoltaic cell is integrated during the watch movement assembly process.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an electronic watch with a photovoltaic cell which does not suffer from the drawbacks described above. This object is achieved by a timepiece movement and by a watch according to the annexed claims.

A timepiece movement according to the invention comprises a photovoltaic cell which is fixed to the upper surface of a support plate, for example by adhesive bonding. On the other side of the cell, on the lower surface thereof, the support plate is provided with a plurality of nuts. An electrical module having a flat surface is attached to the support plate by means of the nuts. The module is provided with several openings whose position and dimensions correspond to those of the nuts, so that the nuts pass through the openings, allowing the flat surface of the module to be placed in contact with the support plate. The module is secured to the support plate by screws, screwed into the nuts. The connection via the nuts secures the photovoltaic cell to the electrical module and ensures shock resistance, without requiring a lateral support. The connection is easy to assemble and disassemble. Preferably, a number of nuts are positioned close to the centre of the support plate, thereby preventing the module and the cell coming apart, which further increases the resistance of the assembly in the event of shock.

Other features and advantages of the present invention will appear in the following description of preferred embodiments, given by way of non-limiting example, with reference to the annexed drawings.

