From the multi-touch_techonologies_v1.01.pdf file :
Agle for FTIR: Anything less than +/- 48 will not take full advantage of
total internal refection, and anything above +/- 48 degrees will escape the
acrylic. In order to ensure there is coverage, going beyond +/- 48 degrees is
fne, but anything above +/- 60 is really just a waste as (60 - 48 = +/- 12 de-
grees) will escape the acrylic
Specs for 486 : http://be.farnell.com/osram/sfh486/ir-emitter-5mm-880nm/dp/1212759
Specs for 485 : http://be.farnell.com/osram/sfh485p/ir-emitter-5mm-880nm/dp/1212738
The SFH486 specs :
IR EMITTER, 5MM, 880NM
Typ Wavelength:880nm
Forward Current:100mA
Max Voltage Vf:3V
Viewing Angle:44°
Case Style:Radial
Operating Temperature Range:-40°C to +100°C
Av Current If:100mA
Fall Time Tf:0.5µs
Full Angle:44°
Half Angle:22°
LED / Lamp Size:5mm / T1.3/4
Peak Wavelength:880nm
Pitch:2.54mm
Radiant Intensity:60mW/Sr
Rise Time:0.6µs
Turn Off Time, t Off:0.5µs
Turn On Time, t On:0.6µs
Typ Voltage Vf:3V
LED Colour:Infrared
No. of Pins:2
SFH485 specs :
IR EMITTER, 5MM, 880NM
Typ Wavelength:880nm
Forward Current:100mA
Max Voltage Vf:3V
Viewing Angle:160°
Case Style:Radial
Operating Temperature Range:-40°C to +100°C
Av Current If:100mA
Full Angle:160°
Half Angle:80°
LED / Lamp Size:5mm / T1.3/4
Max Radiant Intensity:6.3mW/Sr
Min Radiant Intensity:3.15mW/Sr
Peak Wavelength:880nm
Pitch:2.54mm
Radiant Intensity:48mW/Sr
Turn Off Time, t Off:0.5µs
Turn On Time, t On:0.6µs
Typ Voltage Vf:3V
LED Colour:Infrared
-> What means the half and full angle property ?
-> Why is everybody talking about taking the SFH485 leds if, according to the specs and the instructions in the pdf (see text extraction above), the SFH486 seems to be better.
The radiant intensity is higher AND the angle is 44 (160 for the the 485 one). 44° Should be better for TFIR (the 160 ones are better for DI)
PS the 486 is even cheaper than the 485 (0.41 euro to 0.52 euro according to http://be.farnell.com)
