US 5,396,038 AGranted

Thin keyboard switch

AssigneeSMK Corporation

InventorKazunori Yamada

Life of this patent

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Abstract

A key stem of a keyboard switch includes an outer slide and an inner slide. When a key top is struck, the outer slide slides inside of an outer guide, and the inner slide slides inside an inner guide. A first moment point is developed between the outer slide and the outer guide, while a second moment point is developed between the inner slide and the inner guide. A taper at the bottom of the outer slide prevents the second moment point being developed in that location. The reduced horizontal distance between the two moment points helps prevent binding of the key when an actuating force is applied off the axis of the key top. A relationship is disclosed for avoiding sticking or binding in which the horizontal distance between the two moment points, times a coefficient of friction, is less than the vertical distance between the planes of the two moment points.

Claims7

Dependent claims

A thin key switch comprising:

a key cap having a top surface;
a housing;
an inner slide, having a first proximal end and a first distal end, attached at said first proximal end to a one of said key cap and said housing;
an outer slide having a second proximal end and a second distal end, attached at said second proximal end to said one of said key cap and said housing;
said inner slide having a center axis substantially parallel to a direction of movement of said inner slide;
an inner guide rigidly attached to an other of said key cap and said housing;
an outer guide rigidly attached to said other of said key cap and said housing;
said inner slide being slidably inserted in said inner guide;
said outer slide being slidably inserted in said outer guide;
a switch in said other of said key cap and said housing;
said inner slide actuating said switch when said inner slide is moved in said direction of movement;
each of said inner slide and said outer slide being substantially cylindrical in shape with a continuous outer surface;
said outer slide surrounding a portion of said inner slide;
an elastic boot having a first end connected to said key cap and having a second end connected to said housing;
a first portion of said elastic boot having a substantially larger diameter than a second portion of said elastic boot;
said elastic boot being positioned between said inner guide and said outer guide;
a first inner surface of said inner guide;
a second inner surface of said outer guide;
and
said outer slide being shaped to prevent said second distal end from pressing against said inner surface upon a tilting of said key cap, whereby said first distal end contacts said first inner surface and thereby causes said inner slide, rather than said outer slide, to resist said tilting.

17 more elements

A thin key switch comprising:

a key cap having a top surface;
a housing;
an inner slide, having a first proximal end and a first distal end, attached at said first proximal end to a one of said key cap and said housing;
an outer slide, having a second proximal end and a second distal end, attached at said second proximal end to said one of said key cap and said housing;
said inner slide having a center axis substantially parallel to a direction of movement of said inner slide;
an inner guide rigidly attached to an other of said key cap and said housing;
an outer guide rigidly attached to said other of said key cap and said housing;
said inner slide being slidably inserted in said inner guide;
said outer slide being slidably inserted in said outer guide;
a switch in said other of said key cap and said housing;
said inner slide actuating said switch when said inner slide is moved in said direction of movement;
each of said inner slide and said outer slide being substantially cylindrical in shape with a continuous outer surface;
said outer slide surrounding a portion of said inner slide;
an outer point on said top surface at a radial distance from said center axis;
means for returning said key cap to a home position;
a first inner surface of said inner guide;
a second inner surface of said outer guide;
and
said outer slide being shaped to prevent said second distal end from pressing against said second inner surface upon a tilting of said key cap, whereby said inner slide makes contact with said first inner surface, thereby causing said inner slide, rather than said outer slide, to resist said tilting.

16 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/168,989Filed 17 Dec 1993 · continuation
Priority: 15 Jun 1992
Granted: 7 Mar 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H01H 13/705
With contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches: characterised by construction, mounting or…
H01H 2221/024
Actuators: transmission element
H01H 2221/058
Actuators: to avoid tilting or skewing of contact area or actuator
H01H 2221/06
Actuators: to avoid sticking in on position