An assembly comprising a generally spiral hairspring intended for attachment to an oscillating element which is subject to the action of an electromagnetic arrangement synchronizing its frequency with that of a pilot frequency. The turns of the hairspring are divided into two groups or sections, one external group or section of at least one turn and one internal group or section. The groups or sections are connected to each other by a section of hairspring substantially radially disposed with respect to the axis of the hairspring. Two banking stops are provided and so arranged that the radial section, on moving between the stops, encounters them as soon as the angle of oscillation exceeds the limit fixed by the stops.
The invention relates mainly to a hairspring intended to equip the balance wheel of a mechanical timepiece. It is in the form of a spiraled rod (10) cut from an {001} single-crystal silicon plate. Its structure and its dimensions are calculated so as to minimize the thermal drift of the hairspring/balance-wheel assembly by means of the first and second thermal coefficients of its spring constant.
A hairspring and collet assembly for timepieces in which the collet has a base having an opening and a stud integral from the base in a direction parallel to the axis of the opening. The hairspring comprises an inner turn ending in a bend. The stud occupies a portion of the base extending between the opening and the periphery of the base. The non-deformed portion of the inner turn of the hairspring is secured to the stud and the bend extends freely away from the stud about the opening.
