Outdoor Light Sensor

Samuel Greenfeld greenfeld at laptop.org
Wed Jun 13 22:40:34 EDT 2012

Putting the light sensor only on the rear could run into issues if the
screen is facing the Sun and the rear of the XO creates a shadow.

An ugly yet isolated place to put the OLS might be in the neck of the
laptop.  But there isn't much room in that area.  You would need two
openings since the neck doesn't rotate for ebook mode, and therefore
the need to monitor the ebook switch or similar to know which
direction to trust.

It might also be possible to add one or two OLS sensors to the bottom
assembly -- one above the keyboard near the top of the slant, the
other (if necessary) in the rear above the battery.  But fixed sensors
in the bottom would not be exposed to light at the same angle as the

In any case if we move the OLS away from an obvious hole or light
pipe, children are going to have to know not to cover it with stickers
and similar.

On Wed, Jun 13, 2012 at 10:06 PM, James Cameron <quozl at laptop.org> wrote:
> The rear facing storage LED is of less use, since when storage latency
> is important to a user they are typically also operating the unit from
> the front.  There is no display backlight leakage that I can see
> through the rear facing light pipes.
> However, this mounting point would capture light behind the laptop,
> instead of light on the front.  This might also require two drivers
> for the storage LEDs instead of one.
> Otherwise, having disassembled the front face and thought through the
> mainframe volumes ... the only other place I can think of for a light
> pipe is ...
> Below the left lone USB socket, using the same front panel structure
> as for the microphone LED.  It looks to be about the same distance as
> the microphone LED is from the microphone mounting centre.
> However, the forward facing surface of the motherboard is certainly
> bathed in backlight.
> We might also do both, wiring the sensors in parallel.
> --
> James Cameron
> http://quozl.linux.org.au/
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