Banner LX Series - Manual (Page 2)

LX Series Part-Sensing Light Screens
2
P/N 108865 rev. D
Banner Engineering Corp. • Minneapolis, MN U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
Theory of Operation
The LX Series light screen sensing system consists of two self-contained units: an
emitter and a receiver of equal size and sensing range. The emitter has multiple
infrared LEDs spaced at 9.5 mm (0.38") increments, and the receiver has corresponding
photodiodes. The emitter sequentially fires each infrared LED. Multiple photodiodes in
the receiver recognize each of the emitted pulses; the result is a “cross-hatched” optical
pattern. Optical synchronization enables the receiver to recognize light from each of the
emitter LEDs.
The optical crosshatch pattern enables the LX system to detect targets of very small
diameter, and extremely thin, flat objects – as thin as a piece of paper or an envelope.
For small diameter objects, the sensing resolution is less effective at the exact center
(see M.O.D.S. specification) of the sensing range and at the extreme edges of the
pattern (close to the emitter and receiver faces); sensing should take place within the
center 80 percent of the range, as shown in Figure 1.
LX Series sensors are available in two ranges: short and standard. Short-range emitters
and receivers may be located as close together as 75 mm (3"), with a maximum
separation of 200 mm (8"). Standard-range sensors may be separated
150 mm to 2 m (6" to 6.5') apart. Both emitter and receiver must be either short-range or
standard models, of the same length. Detection sensitivity varies somewhat, depending
on the distance between the sensors and the position of the target object.
For closer-range applications, the working range of any sensor pair can be reduced by
connecting the sensor’s Select wire to 0-2V dc (see Specifications; Sensing Range).
The receiver output interfaces directly with dc loads or circuits up to 30V dc, and offers
both sinking (NPN) and sourcing (PNP) output transistors. Outputs conduct whenever
a beam is broken. A 5 millisecond pulse stretcher (OFF-delay) is included to improve
interfacing reliability.
Typical Applications
Typical applications for the LX Series include parts ejection verification and package detec-
tion on a conveyor.
Installation and Alignment
Reliable performance of the LX series light screen systems requires a simple alignment
process. Mounting locations should be as free from vibration as possible.
Sensors may be mounted using the accessory brackets (available separately; see page
4) or using the T-slots in the sensor housings. Loosely mount the emitter and receiver at
their operating locations with their front panels opposite each other, and at approximately
the same level. After mechanical alignment is completed, the sensors can be wired and
power applied.
To obtain optical alignment, adjust the emitter until the receiver detects alignment (the
yellow LED turns OFF). For best alignment, position the emitter in the middle of the
positions that cause a clear receiver condition. After alignment is achieved and the
bracket hardware is tightened, position a pencil or similar object within the sensing area
to verify that it can be reliably detected throughout the sensing area.
LED 1 LED 2
36 mm
(1.4")
10.3 mm
(0.4")
L
31.8 mm
(1.25")
25.4 mm
(1.00")
16.8 mm
(0.66")
10.6 mm
(0.42")
14.0 mm
(0.55")
5.9 mm
(0.23")
2.3 mm
(0.09")
1.8 mm
(0.07")
1.8 mm
(0.07")
NOTE: (2) T-nuts and
(2) M5 - 0.8 x 8 screws
are included with each
sensor
M3 x 0.5 x 5 (4)
max. torque 1.1 Nm
(10 in-lbs)
Figure 2. LX features and dimensions
Figure 1. LX Series optical crosshatch
pattern
Emitter Receiver
Sensing is most effective in the
center 80% of the sensing range
Model Length (L)
LX3 113.4 mm (4.46")
LX6 189.6 mm (7.46")
LX9 265.8 mm (10.46")
LX12 342.0 mm (13.46")
LX15 418.2 mm (16.46")
LX18 494.4 mm (19.46")
LX21 570.6 mm (22.46")
LX24 646.8 mm (25.46")