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Browse Prior Art Database

Method for Sensing User Presence

IP.com Disclosure Number: IPCOM000115948D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Ziemkowski, T: AUTHOR

Abstract

Disclosed is a reflective InfraRed (IR) sensing method for determining when a user is present in a position to use a computing system. An IR Light Emitting Diode (LED) and an IR photo diode are positioned so that light emitted by LED is reflected off the user to be received by the photo diode. An amplified signal from the photo diode indicates user presence. If the user is not present for a certain time, various circuits and devices within the computing system are shut down to conserve electrical energy.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Method for Sensing User Presence

      Disclosed is a reflective InfraRed (IR) sensing method for
determining when a user is present in a position to use a computing
system.  An IR Light Emitting Diode (LED) and an IR photo diode are
positioned so that light emitted by LED is reflected off the user to
be received by the photo diode.  An amplified signal from the photo
diode indicates user presence.  If the user is not present for a
certain time, various circuits and devices within the computing
system are shut down to conserve electrical energy.

      Conventionally, a lack of activity with the system keyboard and
pointing device, over a certain time, has been used to initiate such
a shut-down feature.  The presently disclosed method has the
advantage of not shutting the system in the event that the user reads
and studies the system display screen, without using the keyboard or
pointing device, for longer than the time required to activate the
shut-down feature.

      The Figure is a block diagram showing the major elements
required to implement the presently disclosed method.  An IR beam is
projected from an IR LED 1, which is driven by an amplifier 2
according to the signal of a pulse generator 3.  In this way the IR
beam is modulated by the pulse generator 3, providing IR energy in
the form of a pulse train.

      The LED 1 may be turned on for short pulses, providing a low
duty cycle to conserve power and to allow the LED to be driven with a
rel...