Keyboard switch arrangement and key switch useable therein

Abstract

A keyboard switch arrangement mounted on a base plate and having a plurality of key stem holder blocks, each of which protects a key stem from slipping out and has coupling portions of ridges and grooves on the outer side walls coupled in contiguous relation to one another in a manner that one ridge in one block is fitted in one groove of the adjacent block.

What is claimed is: .[.1. A keyboard switch arrangement comprising in combination: 
     
        adjacent holder block..]. .Iadd.9.  A key switch unit, for use in a keyboard arrangement, comprising: a base plate having a pair of fixed electrodes which are separated by a non-conductive area;   a key unit dismountably retained on said base plate, said unit including a key stem with a push button on top thereof and a key stem holder in slidable engagement with said key stem;   a movable electrode mechanism, disposed between said key unit and said base plate, comprising, assembled into one body, (a) an inverted cup-like resilient cone having a restoring force against deformation by manual depressing of said push button, said cone being provided with an outwardly directed flange extending around the opening thereof, (b) a resilient member, made of an insulating material, fixed to an upper end of said resilient cone and positioned below said upper end, and (c) a movable electrode layer fixed to a lower end of said resilient member; and   an electrically insulating layer disposed between said pair of fixed electrodes and said movable electrode layer so as to form a capacitor switch in combination with said fixed and movable electrodes,   wherein said movable electrode layer is movable downwardly to switch ON when said push button is manually depressed and upwardly to switch OFF by the restoring force of said resilient cone, and   wherein said outwardly directed flange of said cup-like resilient cone is held stably in position between abutting portions of said key stem holder and an upper surface of said plate, thereby causing said cone to envelop said capacitor switch, with the opening thereof contacting the surface of said base plate, and causing said movable electrode mechanism to be retained stably on said base plate while remaining easily removable by means of dismounting said key stem holder from said base plate. .Iaddend. .Iadd.10. A key switch unit according to claim 9, wherein said base plate is provided with engaging holes in which resiliently deformable engaging projections of said key stem holder are inserted for mounting the same on said base plate. .Iaddend. .Iadd.11. A key switch unit according to claim 9, wherein said key stem is of cylindrical shape and is provided with outwardly extending retaining pieces, and said key stem holder is provided with a guide slot and guide portions for preventing said key stem from slipping out and is so disposed that said cylindrical portion slides in said guide slot and said retaining pieces are movably inserted in said   
     
     
        guide portions. .Iaddend. .Iadd.12.  A key switch unit in accordance with claim 9 wherein said electrically insulating layer is disposed on said base plate covering said fixed electrodes. .Iaddend. .Iadd.13. A keyboard switch arrangement, comprising in combination: a base plate having plural pairs of fixed electrodes thereon;   a plurality of key units, each key unit being easily mountable and dismountable on said base plate in association with one of said pairs of fixed electrodes, and each said key unit being arranged in contiguous relation to one another when mounted, each unit including (a) a key stem having a pushbutton on top thereof, and (b) a key stem holder block in slidable engagement with said key stem and having outer side walls;   a plurality of movable electrode mechanisms, each electrode mechanism being retained by each of said key units on said base plate opposite the associated one of said pairs of fixed electrodes, and each comprising, assembled into one body, (a) an inverted cup-like resilient cone having a restoring force against deformation by manual depressing of said push button said cone being provided with an outwardly directed flange extending around the opening thereof, (b) a resilient member, made of an insulating material, fixed to an upper end of said resilient cone and positioned below said upper end, and (c) a movable electrode layer fixed to a lower end of said resilient member; and   an electrical insulating layer disposed between each said pair of fixed electrodes and said associated movable electrode layer so as to form a plurality of capacitor switches in combination with each said fixed electrode pair and the associated said movable electrode layer,   wherein each said movable electrode layer is movable downwardly to switch ON when said associated push button is manually depressed and upwardly to switch OFF by said restoring force of said associated resilient cone, and   wherein said outwardly directed flange of each said cup-like resilient cone is held stably in position between abutting portions of the associated said key stem holder block and an upper surface of said base plate, thereby causing each said cone to envelop the associated said capacitor switch, with the opening of each said cone contacting the surface of said base plate, and causing each said movable electrode mechanism to be retained stably on said base plate, while remaining easily removable by means of dismounting the associated said key stem holder block from said   
     
     
        base plate. .Iaddend. .Iadd.14.  A keyboard switch arrangement according to claim 13, wherein said base plate is provided with engaging holes in which resiliently deformable engaging projections of said each key stem holder block are inserted for mounting the same on said base plate. 
     
     
        .Iaddend. .Iadd.15.  A keyboard switch arrangement according to claim 13, wherein each said key stem holder block is provided with coupling means comprising a groove on one of said outer side walls, a ridge on the opposite outer side wall for being fitted into the groove of a similar adjacent holder block, a plurality of grooves on another outer side wall and a ridge on the other opposite side wall for selectively being fitted in the groove of a similar adjacent holder block, said coupling means interlocking one holder block with adjacent holder blocks stably in various modes on said base plate. .Iaddend. .Iadd.16. A keyboard switch arrangement according to claim 13, wherein each said electrically insulated layer is disposed on said base plate covering the associated one of said fixed electrodes. .Iaddend.