The present invention concerns generally a push-button control device of the type encountered particularly in electronic or electromechanical timepieces. The present invention also concerns a portable electronic instrument, such as a timepiece, including such a push-button control device.
Such push-button control devices are very widespread, particularly in the field of electronic or electromechanical timepieces. A typical example of such a control device is given in EP Patent No. 1 089 144. This document discloses in particular a multi-function push-button contact strip essentially formed of a base fixed to the bottom of a case in proximity to the push-button and an elastic blade forming a mobile contact element capable of being actuated by the push-button. This contact strip forms a first contact element of the control device, the elastic blade of the strip cooperating with a second contact element arranged on an electronic module for establishing an electric connection when the push-button is actuated.
From the electrical and mechanical point of view, the contact is thus formed of two contact elements, one mobile (namely the aforementioned elastic blade capable of being actuated by the push-button) secured to the case by its base and the other fixed, which is arranged on the electronic module (typically a contact pad arranged on the printed circuit board of the electronic module). In the aforementioned EP Patent No. 1 089 144, the second contact element is for example formed of a bent conductive lug of the printed circuit. It will thus be understood that the two contact elements are arranged on different frames, namely the case (to which the push-button is typically secured) for the first contact element, and the printed circuit board, for the second contact element.
One drawback of the aforementioned typical construction lies in the fact that the printed circuit board constitutes an element whose dimensions and position in the case cannot be guaranteed with a high level of precision. This lack of precision leads to a loss of precision as to the arrangement and travel of the push-button, which consequently has repercussions on the quality of actuation and use of the push-button. In order to improve precision, it is thus necessary to find another solution or at least to improve the existing solutions.
Another drawback of the aforementioned typical construction also lies in the liability of the contact to wear. In fact, the fixed contact element with which the mobile contact element is brought into contact, is generally made in the form of a metallisation made on the printed circuit board or a part secured to the printed circuit. Following repeated mechanical contacts between the contact elements, this metallisation can undergo significant wear and consequently reduce the quality of the electric contact. It is thus also sought to reduce the liability of the push-button control device to wear.