depending on what wavelength of IR it's sensitive to it could be used to
measure temperature, to detect fires, or to detect intruders.  when used
in a "motion" detector they are usually used with lenses that have bands
or grids of blind spots so that when someone walks past they are
alternately seen and not seen and thus generate a series of pulses, this
way you can avoid trips from heat ducts and such and only see things
moving across the field of view.

for the same reason most motion sensors fail if you walk directly
towards them, since you will be staying in view or out of view, or if
you move very, very slowly since you generate pulses too slowly and it's
discarded as noise.  of course in better alarm installations multiple
sensors are setup so that walking towards one means moving across the
field of view of another, and moving slowly enough is very, very hard.

this also means that shielding your heat doesn't make you "invisible" to
them because there will be natural heat sources in the room and when you
and your heat shield pass in front of them you'll be generating a pulse,
hence the phenomenon where snow can turn on a light with a motion sensor.

or they may be used for communications circuits where other circuitry
will remove the dc background signal and control the bandpass or where
you need to know when the background is so high that it's blinding the
detector and blocking any signals.  it's also useful in determining the
signal strength in some cases (particularly if aligning a "line of
sight" system).

Lindy Mayfield wrote:
>
> Hi.  I have a TSL260R infrared light to voltage detector that I wanted to use for a proximity detector.  I've since come to the conclusion that it works ok in some instances, but not really for a robot.
>
> So I began to wonder what this detector is normally used for, what sorts of applications, etc.  The datasheet doesn't mention anything.  Any ideas?
----------

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu