Advantech IDK-2117 Series User Manual page 34

Note5 Definition of response time
The output signals of the photo detector are measured when the input signals are
changed from "Full Black" to "Full White" (rising time), and from "Full White" to "Full
Black "(falling time), respectively. The response time is an interval between 10% and
90% of amplitudes. Please refer to the figure below.
Optical Optical
response response
IDK-2117 User Manual
%
Tf
100
90 90
White White
10 10
0 0
Black Black
28
Tr Tr
White White