Sorhea Products » Operation of Infrared Technology

Operation of Infrared Technology

Infrared

Infrared barrier bases its technology on emission and reception of an infrared signal. The cell in a column produces a beam that has a wavelength greater than that of visible light and is totally invisible to the naked eye.

Active infrared

Active infrared is generated by an infrared light source facing a receiver analysing the signal.
In order to obtain good signal performances, beams are pulsed to transmit a lot of energy in saving components lifetime.

Problematic

Infrared beams are generated by a light source made directional with an angle of about +/- 2°. The cone is about 3m height 100m from the source, thus all receiver cells pick up the signal from 1 transmitter cell.

Solution

To detect it is necessary to analyse the state of each beam independently.

Means: temporal multiplexing: make the difference between the beams

The infrared beams are generated one by one at a period of 1 ms (time between 2 emissions of 2 adjacent beams). It permits to make the different between the beams so the received cell can analyse the signal only from the transmitter facing it.

Realisation

The temporal multiplexing is realized by a synchronization between the columns. It can be done by a cable or an optical data encryption in the beams.

Optical synchronization permits to simplify the installation but is limited in terms of number of beams (maximum: 6). The wiring synchronization can propose a protection made by 18 cells.

To increase the number of cells in a barrier optically synchronized, the solution consists in stacking the products. The selectable channels permit to make the difference between them avoiding interferences.