External presence detector module for screen

[Frederic_L]

Hi,

I work for GreenIT.fr, the site of the French-speaking community of Green IT (sustainable development in information technologies).

We relayed a few weeks ago the release of a series of Eizo screens which have the distinction of being equipped with a presence detector (see http://www.greenit.fr/article/materiel/eizo-invente-lecran-qui-seteint-tout-seul ). As soon as the user is absent for more than 40sec, the screen turns off by itself.

I find the functionality nice, it is in my opinion more effective than turning off the monitor via Windows which cuts the screen when it no longer detects activity via the mouse or the keyboard, which has the gift of me. piss off when watching a movie ...

Hence my question on this forum handyman : Is it possible to create a presence detection module that would be adaptable on any computer screen (and why not on any TV!).

The direct advantage is to be able to provide functionality that saves energy to an already deployed screen fleet without requiring the replacement of equipment (the production and recycling of computer equipment pollutes much more than all its power consumption during use).

I would imagine a module that would plug in just before the outlet (like a wattmeter), with a remote module that could be placed on the desk, directed towards the user.
And for laptops, we can imagine the same module, but in USB, which could "order" Windows (or other) to turn off the screen.

The detector should detect the user rather according to his heat than movement, precisely to prevent the screen from turning off during the viewing of a film during which one is rather motionless.

This kind of device may already exist, but my research has been unsuccessful for the moment ...

[Obelix]

Hello,

Two technologies can be implemented:
1) Passive infrared or not
2) Sonic by ultrasound.

For computers my preference is for more stable ultrasound at short distance.
For TV a passive IR detector should do the trick.

A search with google on "infrared presence detector" or "ultrasonic presence detector" gives many results ...
Prices within 20 to 30 Euros no more!

Obelix

[Frederic_L]

Hi Obelix,

Thank you for your answer.

If I understand correctly (with my modest knowledge of physics), the infrared detector detects presence by our heat, while sonic ultrasonic technology detects our presence by movement.

How far away does the ultrasonic detector work? Is it sensitive enough to detect a static person watching a movie for example?

So it is a product that exists?
A Google search on "Infrared presence detector" or "ultrasound" indeed gives a lot of results, but all I find are presence detectors for alarms or for lighting, often rather cumbersome .. and nothing tells me if it is adaptable to any electrical device without modification.

[Obelix]

Hello Frederic_L,

Be careful not to confuse presence detector and motion detector.
A motion detector is much simpler to realize. We have a stable state which only depends on the environment and any modification of this state leads to the presence of an intrusion.
A presence detector must necessarily measure a parameter to detect and it is this measurement that poses the problem.
In infrared we can detect the heat "of the scene" but beware the threshold is difficult to apprehend because changing according to the day and time!
In ultrasound we measure distances, and the measurement is easier because the place where we measure is easier to determine! (See on a polaroid the big black patch next to the objective which is a distance meter for autofocus!)
The maximum "useful" distance is of the order of five meters. But what interests us is the resolution: is there someone slumped in the sofa or not?

The search on google must be patient, because the results are numerous. But not everything we find fits the criteria. So first formalize the essential criteria, then compare with the proposed detectors.
The boxes offered are often huge, once opened the electronics use only a small part of the box.

An example: http://www.interface-z.com/produits/cap05_ultrason.htm

Obelix