Patent GB-1200109-A (GB)
Title: Magnetically operated electrical indicator.
IPC: G08B5/24
Filed: 1967-08-02
Abstract: 1,200,109. Electromagnetically operated indicators. CONSOLIDATED ELECTRONICS INDUSTRIES CORP. 2 Aug., 1967 [8 Aug., 1966; 24 July, 1967], No. 35441/67. Heading G4F. [Also in Division H1] An indicator is operated by a pivoted armature displaceable to two end positions by an electro-magnet and held in these positions by permanent magnetism of the armature, the core of the electromagnet being connected to switches operated by the armature so that a coil circuit is broken when the armature reaches the end position and the flow of current is reduced to a minimum. In Fig. 1, the armature 31 is located between two polepieces 26, 27 of an electromagnetic having coils 22, 23. The armature is displaced to positions in which either stop 32C is in contact with polepiece 27 or stop 32B is in contact with polepiece 26, the attainment of the positions opening a corresponding switch 34, 33 or 37, 36 whereby the operating current is interrupted, the armature being held in position by its permanent magnetism. The condition of the indicator is detectable through an aperture in the right hand end wall through which is displayed differently coloured portions of a bent over part 32A of a disc attached to the armature The armature may have different shapes (Figs. 6 to 16, not shown) which figures illustrate blunt, flat and rounded shapes of the armature ends. Magnetic sticking may be avoided as shown by preventing the armature contacting the polepieces, or by covering the armature ends with tape to prevent direct contact (Fig. 6) or by allowing only a corner of the armature to contact the polepieces. The polepieces may also have a variety of shapes which include inturned ends, dimples formed along their length to provide contact areas for the armature and arcuate portions conforming with arcuate ends of the armature. The electric switch contacts shown comprise fixed posts 34, 37 contacted by conductive spring members 33, 36 which may be moved away from the post by the lip 32d, 32e on the disc 42 secured to the armature. The spring contacts may be constituted by two parallel members of different vibration frequency so that the effects of balance are minimized. The contact surface of the spring member may be turned outwardly as in Fig. 16, not shown, to provide a rubbing surface sufficient to keep the contact clean. Alternatively, the underneath of the disc 32 could be printed with a conductive area which shorts a central contact to one or either of two outside contacts depending upon the position of the disc (Fig. 9, not shown). The core arrangement may comprise two magnetic cores 22, 23, a bifilar wound coil or a single coil connected to appropriate changeover circuits and the indicator is operated by the net effective current flow in the coils. The operating circuit (Fig. 4) may be a transistor printed circuit arrangement. A 0À25 V input at terminal 40 will cut-off transistor 57 and allow transistor 56 to conduct. Core 22 will be energized and switch over the indicator, the movement of the indicator eventually breaking contact 36 so that current ceases. A 3À6 volt input at 40 will render 57 conducting and so cut off 56. It will also render 58 conducting energizing core 23 so restoring the indicator and interrupting the coil current. Diodes 59 and 60 prevent interfering voltages being produced. The indicating arrangement is formed by the bent over lip 32A of disc 32 which has two coloured respectively visible through an aperture in the end wall 47A at the two positions of the indicator. The lip may alternatively have two flat faces (Fig. 5, not shown). A further indicator (Figs. 6 and 7, not shown) utilizes an arm which is swung between two positions by the armature so as to rotate an indicator disc between two positions. No switching means is illustrated for this alternative. The construction takes the form of a box having a ceramic base upon which the circuitry is printed. A package (28a) contains the electronic components. The polepieces may be shaped so as to contact the ceramic base and be soldered thereto so that the base forms a heat sink. In Fig. 6 (not shown), the case is of cylindrical construction.