Browse Prior Art Database

Light Controlled Software Products

IP.com Disclosure Number: IPCOM000109338D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 3 page(s) / 137K

Publishing Venue

IBM

Related People

Appino, PA: AUTHOR [+5]

Abstract

Ambient light, whether artificial or natural, can affect the visibility of text or graphics on a computer display terminal. This article describes concepts by which computer software can react to changes in room light intensity. These changes can include adjustments to visual display attributes and initiation of specific tasks. As it is often useful for the human user to know about the intensity of ambient light, a light-meter icon is also described.

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

Light Controlled Software Products

       Ambient light, whether artificial or natural, can affect
the visibility of text or graphics on a computer display terminal.
This article describes concepts by which computer software can react
to changes in room light intensity.  These changes can include
adjustments to visual display attributes and initiation of specific
tasks.  As it is often useful for the human user to know about the
intensity of ambient light, a light-meter icon is also described.

      For the computer software to make changes to the video display
in response to changes in light intensity, the level of light must be
measurable.  One means of monitoring the ambient light at the
computer or workstation screen is shown in Fig. 1.  Circuitry 10 is
driven by an input DC voltage 11, which may come from the computer
itself or a battery.  The flow of current through an NPN transistor
12 is regulated by a light-sensitive cadmium sulfide (CdS) cell 13,
which results in an analog output voltage 14 proportional to the
light falling on the CdS cell.  An optional bandpass filter 15 may be
placed over the CdS cell to make it sensitive to a particular range
of light wavelengths, e.g., red.  A bank of circuits 10 each with a
different bandpass filter could be used to monitor a plurality of
light wavelengths.  Alternately, one circuit 10 could be used with a
plurality of bandpass filters periodically rotating over the CdS cell
13.  Intermittent dead and clear zones of known durations in the
rotating platform would be used by the computer to determine its
orientation, which would allow determination of which bandpass filter
was currently over the CdS cell.

      The physical location of this CdS photocell could be at any
convenient place on the exterior of the computer terminal.  Near the
on/ off switch of the terminal might be a good location, since this
area is necessarily exposed to the ambient environment.

      The analog output from each circuit 10 could be routed to a
low-cost Analog to Digital (A/D) converter 30, the digital output of
which would be available to the computer system at a known data
address.  Alternately, the output of a commercially available light
meter could be sent to the A/D converter.

      Although the computer will adjust the video display
automatically based on the levels of ambient light measured, the user
may wish to have the amount of light visually quantified on the
computer terminal via an icon.  This icon would consist of one or
more bars indicating the ambient light intensity measured by the
respective circuitry.  As shown in Fig. 2, a small * in each bar
moves from low (left side of bar) to high (right side of bar),
depending on the respective light level.  Fig. 2 is shown with the
t...