OCB100-KIT Datasheet, PDF (14/24 Pages) OPTEK Technologies – Auto-Calibration Design Kit

THEORY OF OPERATION OPB885Z / OPB885CZ
The OPB885Z is a wide gap slotted (transmissive) switch with a
single mounting tab on the phototransistor side of the assembly.
Current forced through the LED provides a light signal with a center
wavelength of 890nm directed across the open gap of the switch
toward the phototransistor sensor. The Ic_(ON) collector current of the
phototransistor is dependent on the amount of light striking it. When
a non-transparent target passes through the gap, the amount of col-
lector current is lowered significantly. The three graphs on the follow-
ing page show the effect of an opaque target passing next to the LED
tower, next to the phototransistor tower, and in the center of the slot.
14 ^{Analysis of these graphs shows a narrower signal area next to both}
towers. This effect is due to the beam angle and acceptance angle
of the LED and phototransistor of about 40° and the presence of a
.05”[1.27mm] wide aperture in front of each component.
OCB100-KIT