Sound generator in particular for a timepiece
AssigneeETA SA Fabriques d'Ebauches
InventorRudolf Bugmann
Life of this patent
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Abstract
A sound generator comprises a transducer (3) intended to be supplied with a signal having a frequency determining the sound to be produced and having a variable amplitude (envelope). To this effect, the transducer is connected in series with the principal path of a semiconductor component (5). The control electrode of this semiconductor component (5) is connected to a RC-circuit (1, 7) capable of providing control pulse trains having said envelope. The RC-circuit comprises a capacitor (7) and at least one input branch (13) of a current mirror (11) the output branch (12) of which supplies a control electrode of the semiconductor component (5). Preferably, the capacitor (7) is connected in series with the input branch (13). Application in particular to wrist-watches equipped with an audible alarm.
Claims9
A sound generator, in particular for use an alarm in a timepiece, intended to generate sounds of variable amplitude and comprising an acoustic system connected in series with a controlled current source, a control electrode of said controlled current source being connected to a control circuit comprising a capacitor and which is capable of providing a control signal having a frequency which determines the note to be produced and having an envelope corresponding to said variable amplitude, wherein said control circuit further comprises a current mirror the output branch of which supplies said control electrode and an input branch of which is connected in series with said capacitor.
Dependencies are inferred from the claim text.