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US 4,380,704 AGranted
Electrical switch
OwnerMichael S. Wisdainventor
Life of this patent
Estimating the term…
Abstract
An electrical switch that can be used in corrosive and explosive environments as well as under water. The switch is constructed of reed switches mounted on a printed circuit board. The printed circuit is connected with a power cable and the entire board and elements are encased in a tough, non-corrosive insulating medium. A control shaft mounting a permanent magnet extends through the casing with the magnet mounted on the outside of the casing adjacent the controlled reed switch.
Claims12
An electrical switch for use in explosive environments, under water, and the like, comprising
- a printed circuit board having an electrical circuit pattern deposited thereon, at least a single magnetic reed switch mounted on said board and connected in electrical series circuit relationship with the electrical circuit pattern on said board, the reed switch having switch contacts in a normally open circuit condition,
- an electrical cable having a plurality of electrical conductors arranged therein in an insulatively spaced relationship, said cable being constructed of an electrical insulative material, and being adapted to have one end of each of the electrical connectors connected to an electrical power source,
- means for electrically connecting the remaining ends of the individual electrical conductors of the cable in circuit relationship with the electrical circuit pattern of the printed circuit board to provide an electrical circuit path on the printed circuit board through the reed switch to thereby electrically switch the power through the electrical cable in accordance with the electrical circuit condition of the reed switch,
- means for completely encapsulating the printed circuit board including the circuit pattern thereon and the connected reed switch and a portion of the electrical cable beyond said cable conductor connecting means in an electrical insulative medium to form a solid unit without any voids in the insulative medium to thereby eliminate any exposed electrical contacts externally of the insulative encapsulated medium whereby the encapsulated elements may be completely immersed in an explosive or corrosive environment, under water or the like,
- said encapsulating medium including an aperture spaced adjacent the reed switch while being spaced from the circuit pattern on the printed circuit pattern and extending through the printed circuit board to permit mounting a control shaft therethrough,
- a control shaft mounted in said aperture for rotation therein,
- one end of the control shaft mounting a permanent magnet rotatable with the control shaft to operate the encapsulated reed switch in accordance with the positions of the magnetic poles of the magnet to thereby provide an electrical circuit path through the cable, printed circuit pattern on said board and the closed contacts of the reed switch when the contacts are magnetically operated by said permanent magnet to a closed circuit position.
4 more elements
A method of constructing an electrical switch having no electrical contacts exposed to the environment to permit the switch to be safely used in corrosive and aqueous environments, including the steps of
- providing a printed circuit board having an electrical circuit pattern deposited thereon,
- mounting an encapsulated magnetic reed switch on said board in an electrical circuit relationship with the electrical circuit pattern thereon,
- electrically connecting the individual conductors of a power cable to the circuit pattern on said board to define an electrical circuit through the power cable, electrical circuit pattern and reed switch,
- encapsulating the entire printed circuit board assembly including the reed switch and the portion of the power cable adjacent to the connection of the power cable by flowing an insulative medium thereon so that only the unencapsulated portion of the power cable extends into the environment outside of the encapsulated, hardened assembly, the encapsulation step completely insulating all portions of the printed circuit board assembly to prevent any undesirable electrical interaction between the elements thereof,
- mounting a permanent magnet on the outside of the encapsulated printed circuit board assembly in a fixed position relative to the reed switch to permit the magnet to be controllably magnetically oriented relative to the reed switch to cause the contacts thereof to open and close in accordance with the magnetic orientation of the magnet;
- the step of mounting the permanent magnet includes the steps of providing an aperture on the printed circuit board adjacent the location of the reed switch but insulatively spaced therefrom, and the step of encapsulation includes constructing and defining an aperture in axial alignment with the aperture on said board,
- mounting a control rod through said aligned apertures for rotation therein, and
- mounting the permanent magnet on one end of the control rod for orienting same with respect to the reed switch.
5 more elements
Dependencies are inferred from the claim text.