Electromagnetic non-acoustic alarm with electromagnetic motor having movable and stationary circuits with resilient connection elements
View Patent ↗A non-acoustic alarm for a portable object includes an electromagnetic motor which can be electrically controlled in order to generate a vibratory effect. The electromagnetic motor includes a movable magnetic circuit and a stationary magnetic circuit. The movable magnetic circuit includes a coil, a ferromagnetic core coupled to a magnetic cage forming an extension of the ferromagnetic core. The magnetic assembly of the movable magnetic circuit constitutes a movable magnetic mass of the non-acoustic alarm capable of generating the vibratory effect. The non-acoustic alarm includes resilient connection elements resiliently connecting the movable magnetic circuit to the stationary magnetic circuit. The resilient connection elements are shaped to guide and ensure that the movable magnetic circuit undergoes a linear, or quasi-linear, oscillatory motion during the electrical control of the electromagnetic motor.
1 . A non-acoustic alarm for a portable object comprising:
an electromagnetic motor configured to be electrically controlled in order to generate a vibratory effect, wherein the electromagnetic motor comprises a movable magnetic circuit and a stationary magnetic circuit, said movable magnetic circuit comprising a coil, a ferromagnetic core coupled to a magnetic cage forming an extension of the ferromagnetic core, a magnetic assembly of said movable magnetic circuit constituting a movable magnetic mass of said non-acoustic alarm to generate said vibratory effect; and
resilient connection elements resiliently connecting the movable magnetic circuit to the stationary magnetic circuit, the resilient connection elements being shaped to guide and ensure that the movable magnetic circuit undergoes a linear, or quasi-linear, oscillatory motion during the electrical control of the electromagnetic motor,
wherein the resilient connection elements belong to a support that receives the stationary magnetic circuit and the movable magnetic circuit, and
wherein the support comprises a stationary part receiving the stationary magnetic circuit and a movable part receiving the movable magnetic circuit, the resilient connection elements mechanically connecting the movable part of the support to the stationary part thereof, while guiding the movable magnetic circuit and ensuring that the movable magnetic circuit undergoes the linear, or quasi-linear, oscillatory motion during the electrical control of the electromagnetic motor.
2 . The non-acoustic alarm for a portable object according to claim 1 , wherein the stationary part of the support comprises a fastener configured to make the stationary part of the support integral with the portable object.
3 . The non-acoustic alarm for a portable object according to claim 1 , further comprising an electronic control unit configured to supply electrical power to the coil so as to cause the movable magnetic circuit to oscillate at the resonant frequency thereof.
4 . The non-acoustic alarm for a portable object according to claim 1 , further comprising an electronic control unit configured to supply electrical power to the coil so as to cause the movable magnetic circuit to oscillate at a chosen frequency between 120 Hz et 250 Hz.
5 . The non-acoustic alarm for a portable object according to claim 1 , wherein the support is formed by a lower half-shell and an upper half-shell shaped to encapsulate the movable magnetic circuit and the stationary magnetic circuit of the electromagnetic motor.
6 . The non-acoustic alarm for a portable object according to claim 5 , wherein each half-shell of the support comprises two lateral resilient tabs forming the resilient connection elements, configured to laterally flank the electromagnetic motor.
7 . The non-acoustic alarm for a portable object according to claim 1 , wherein the magnetic cage comprises two branches forming pole shoes configured to guide a magnetic flux induced by the coil in the vicinity of the stationary magnetic circuit.
8 . The non-acoustic alarm for a portable object according to claim 7 , wherein the two branches forming the pole shoes and the ferromagnetic core delimit, together with the stationary magnetic circuit, an air gap extending perpendicularly to the linear, or quasi-linear, oscillatory motion of the movable magnetic circuit.
9 . A portable object comprising:
the non-acoustic alarm according to claim 1 .
10 . The portable object according to claim 9 , wherein the portable object is a timepiece.
11 . The non-acoustic alarm for a portable object according to claim 1 , wherein the stationary magnetic circuit comprises two elements made of magnetic material.
12 . The non-acoustic alarm for a portable object according to claim 11 , wherein the two elements made of magnetic material are permanent magnets.
13 . The non-acoustic alarm for a portable object according to claim 12 , wherein the stationary magnetic circuit comprises a shunt to close the magnetic flux at the stationary magnetic circuit.