Browse Prior Art Database

Elimination of Skew in Double Pole Switches

IP.com Disclosure Number: IPCOM000082310D
Original Publication Date: 1974-Nov-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Corriere, CJ: AUTHOR

Abstract

When using multipole mechanical switches in an application such as a matrix keyboard, where the appropriate pair of X,Y lines is activated when a button PB is depressed, a contact closure skew problem can exist. It is usually unpredictable as to which contact will close first.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Elimination of Skew in Double Pole Switches

When using multipole mechanical switches in an application such as a matrix keyboard, where the appropriate pair of X,Y lines is activated when a button PB is depressed, a contact closure skew problem can exist. It is usually unpredictable as to which contact will close first.

The illustrated method of wiring the switches is such that a chosen contact will always become active after or simultaneously with the other contact. This allows the chosen contact output to be used by the logic as a signal that the switch outputs are valid.

Fig. 1 shows a double-pole switch wired such that output B will always become active (ground) either after or simultaneously with output A, but never before it. In effect, an AND function has been built into the switch via link L, such that B cannot be active unless A is active.

Fig. 2 shows this concept applied to a m,n matrix of switches. In this example, the Y output corresponding to the matrix switch actuated will become active before or simultaneously with the corresponding X output.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]