Magnetic latching and damping for electromagnetic indicators

A bistable electromagnetic indicator for providing binary indication of first and second conditions comprising:

• a housing;
• first and second indicator discs supported on a central axis in coaxial spaced relation at one end of said housing and at least said first disc adapted for rotation about said axis whereby when said first disc is in a first of two bistable dispositions said discs indicate one of said conditions and whereby when said first disc is in a second bistable disposition said discs indicate the second of said conditions;
• electromagnetic means including at least one electromagnet having a core and a winding therearound;
• means adapted for connecting said winding to a source of current whereby said core of said electromagnetic means may be alternately polarized;
• a first permanent magnet;
• means immovably supporting said electromagnetic means and said first permanent magnet in said casing so that an end of said core and said first permanent magnet are directed axially and extend coextensively toward said discs;
• a second permanent magnet having two ends disposed along a polar axis substantially normal to said central axis and having two magnetic poles disposed along said polar axis;
• means supporting said second permanent magnet for rotation about said central axis between first and second limit positions, said second permanent magnet supporting said first indicator disc and moving said disc between said first and second limit positions which define said first and second bistable dispositions, respectively, said second permanent magnet being driven from said first to said second bistable disposition by magnetic forces upon application of a signal to said electromagnetic means;
• flux permeable means that many be moved into mechanical engagement either with said core of said electromagnetic means, when the indicator is either in the first or second bistable position, or with said first permanent magnet, when the indicator is to be reset from said second bistable position, thereby to form an extension of said core of said electromagnetic means or said first permanent magnet, respectively, whereby said flux permeable means is magnetized in accordance with the magnetic field of said core of said electromagnetic means or said first permanent magnet, said flux permeable means disposed in the path of movement of said second permanent magnet for magnetically latching said second permanent magnet in one of said limit positions;
• means for rotating said flux permeable means about said central axis from a position of engagement with said electromagnetic means to a position of engagement with said first permanent magnet, whereby said first indicator disc and said second permanent magnet are likewise moved about said central axis until said flux permeable means is repulsed to cause said first indicator disc and said second permanent magnet to move a further distance in the same direction of rotation to return to said first bistable disposition;
• means biasing said flux permeable means toward said position of engagement with said electromagnetic means;
• and
• auxiliary magnetic latching means for aiding in magnetically latching said second permanent magnet in one of said limit positions, said auxiliary magnetic means comprising a plurality of auxiliary permanent magnets, the magnetic fields of said plurality of auxiliary magnets acting upon said second oermanent magnet so as to latch said second permanent magnet in one of said two limit positions until said flux permeable means is magnetized in accordance with the magnetic field of the magnetic means with which said flux permeable means is in contact with, either said core of said electromagnetic means or said first permanent magnet.