Electrical keyswitch
AssigneeIllinois Tool Works Inc.
InventorRaymond Barnoski
Life of this patent
Estimating the term…
Abstract
A low profile keyswitch for electrical keyboards is disclosed which has the capability of being operated either as a contactless analog type of keyswitch, or as a mechanical contact type of keyswitch. The keyswitch may include a pair of normally-closed contacts that are opened when a separator bar that is integrally formed in the interior of the plunger passes between the contacts as the plunger is depressed. Alternately, a permanent magnet may be carried on one side of the plunger to control the magnetic saturation state of a closed-loop magnetic core which, along with a pair of U-shaped conductive lines that thread through the core, is inserted into a retaining well formed by a pair of walls that project upwardly from a horizontal surface of the base at a location adjacent the side of the plunger that carries the magnet.
Claims4
In an electrical keyswitch comprising a base having a vertically extending guide chamber and a horizontal surface, a depressible plunger mounted for up and down movement within said guide chamber, a return bias spring positioned in said guide chamber so as to bias said plunger upwardly toward its undepressed position, a permanent magnet carried externally on one side of said plunger so as to move up and down therewith, a closed-saturable magnetic core, a U-shaped drive line having two substantially straight parallel legs that has one of said legs located in the loop of said core with an adjoining strip of said drive line running between its two legs and being located above said core and a U-shaped, sense line having two substantially straight parallel legs that has one of said legs located in the loop of said core so as to run parallel to the leg of said drive line that is located in said loop with a joining strip of said sense line running between its two legs and being located above said core, wherein said permanent magnet is positioned adjacent said core when said plunger is not depressed so that said core is substantially magnetically saturated, and so that said permanent magnet moves away from said core when said plunger is depressed, thereby allowing said core to come out of magnetic saturation;
- the movement comprising a plurality of electrically insulating, elongated, parallel dividers that are integrally formed on said base and are located below said horizontal surface in the interior of said base adjacent the side of said base that is adjacent said permanent magnet so that said dividers in conjunction with said base provide four separate elongated passageways and a pair of walls that extend vertically upward from said horizontal surface that are shaped to form a retaining well for said core so that the bottom of said core rests on said horizontal surface and the top of said core is uncovered and the axis of said core is vertically oriented, said walls each having a groove therein, one of said grooves positioned to allow said drive line to pass therethrough and the other of said grooves positioned to allow said sense line to pass therethrough, said horizontal surface having a slot therein which allows both of said drive and sense lines to pass therethrough, with each of said legs of said drive and sense lines being confined to operate in one of said passageways that are provided by said dividers so that the lower ends of said legs extend out of the bottom of in said base at different, electrically insulated locations, said passageways.
Dependencies are inferred from the claim text.