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Browse Prior Art Database

Fiber-Optic Data Entry Device Or Keyboard

IP.com Disclosure Number: IPCOM000102551D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 84K

Publishing Venue

IBM

Related People

Rudisill, CA: AUTHOR [+2]

Abstract

This article describes an electrically passive keyboard design that uses optical means to sense keybutton depression. Optical signals originating in a remote system logic unit travel over an optical fiber to the keyboard unit, are modulated by keybutton depression and return to the logic unit over the optical fiber. The elimination of the electronics and wiring from the keyboard has advantages in the elimination of electromagnetic interference generation and electrostatic discharge susceptibility in the keyboard and cable attaching it to a system unit. It also eliminates problems from electrical contact bounce, electrical signal cross-talk, the need to send electrical power over the connecting cable and contact moisture and corrosion sensitivity.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 72% of the total text.

Fiber-Optic Data Entry Device Or Keyboard

       This article describes an electrically passive keyboard
design that uses optical means to sense keybutton depression.
Optical signals originating in a remote system logic unit travel over
an optical fiber to the keyboard unit, are modulated by keybutton
depression and return to the logic unit over the optical fiber.  The
elimination of the electronics and wiring from the keyboard has
advantages in the elimination of electromagnetic interference
generation and electrostatic discharge susceptibility in the keyboard
and cable attaching it to a system unit.  It also eliminates problems
from electrical contact bounce, electrical signal cross-talk, the
need to send electrical power over the connecting cable and contact
moisture and corrosion sensitivity.  The reduced number of
opto-electronic devices with this particular multiplexing design
makes it lower cost than traditional optical approaches.

      Fig. 1 illustrates the basic operating principle.  When a
keybutton is depressed, movement is imparted to mechanical actuators
which, in turn, open one or more normally closed beam
blocking/reflecting transducer plates allowing light to be
transmitted through the transducers to the output of the keyboard.
Each blocking/reflecting plate does not allow light transmission to
the output side of the light guide except when actuated.  Fig. 2
shows a cross-section detail of the transducer area of the keyboard.

      Alth...