US 4,172,251 A · Self-encoding key switch and keyboard and keyboard system utilizing the same

Abstract

A self-encoding key switch is formed of a body having a well for storing a pool of mercury, a plurality of contact chambers with encoding contacts therein and having channel portions communicating with the well of a size to resist flow of the mercury therethrough due to surface tension of the mercury, and a plunger movable into the well to force the mercury through the channel portions into the contact chambers to momentarily connect the encoding contacts thereby providing tactile feedback, self-encoding and N-key rollover. A keyboard system utilizes a plurality of the above-described self-encoding key switches along with a register, and a strobe contact is disposed in a contact chamber of each key switch such that the trailing edge of the signal from the strobe contact precedes the breaking of electrical connection between a supply contact in the body and the encoding contacts to trigger the register and enter coded data from the encoding contacts. A keyboard formed of a plurality of the above-described, self-encoding key switches is constructed with the bodies of each of the key switches formed of a single piece of plastic material mounted on a base member carrying electrical connectors forming the contacts in the key switches. In one embodiment, the electrical connectors are in the form of conductor bars extending through the base member which is integrally formed with the switch bodies as a single unit. In another embodiment, the base member has surface carried connectors in the manner of a printed circuit board.

Claims21

Dependent claims

An electrical key switch comprising

body means including well means, a pool of electrically conductive liquid stored in said well means, contact chamber means having channel means communicating with said well means, and relief chamber means disposed over said contact chamber means for receiving said liquid from said contact chamber means and returning said liquid to said well means, said channel means having a cross sectional size to preclude free flow of said liquid therethrough due to surface tension of said liquid, said pool of liquid being of sufficient quantity to extend from said well means through said channel means to said contact chamber means;
electrical contact means positioned in said contact chamber means;
and
plunger means movable into said well means to force said liquid to pass through said channel means into said contact chamber means and into said relief chamber means for return to said well means to momentarily contact said electrical contact means.

1 more element

A keyboard system comprising a plurality of electrical key switches each formed of a body defining a well, a pool of electrically conductive liquid stored in said well, a plurality of contact chambers communicating with said well via channel means having a cross sectional size to preclude free flow of said liquid therethrough due to surface tension of said liquid, and relief chamber means disposed over said contact chamber means for receiving said liquid from said contact chamber means and returning said liquid to said well, said pool of liquid being of sufficient quantity to extend from said well through said channel means to said contact chambers, a plurality of electrical contacts including strobe and encoding contacts each disposed in one of said contact chambers and a supply contact, and plunger means movable into said well to force said liquid through said channel means into said contact chambers and into said relief chamber means for return to said well to momentarily connect said electrical contacts;

register means having a plurality of data inputs and a strobe input;
means connecting each of said supply contacts of said key switches with a supply potential;
a plurality of data connector means each connected with one of said data inputs of said register means, predetermined ones of said encoding contacts of each of said key switches being connected with predetermined ones of said connector means;
and
strobe connector means connecting each of said strobe contacts of said key switches with said strobe input of said register means whereby actuation of any of said key switches produces coded data signals on said encoding contacts and a strobe signal on said strobe contact to enter said coded data signals into said register means.

2 more elements

Dependencies are inferred from the claim text.

Self-encoding key switch and keyboard and keyboard system utilizing the same

Life of this patent

Self-encoding key switch and keyboard and keyboard system utilizing the same

Life of this patent

Abstract

Claims21