Part presence on a dark conveyor
Detects a light part while ignoring the black belt behind it.
Photoelectric · Background suppression
LFN-CX44 Background Suppression Photoelectric Sensor
A background-suppression sensor with three spot geometries — small, large and strip (bar-shaped) — so a 100/200/300 mm window can be set to ignore whatever s
Model LFN-CX441 / 442 / 443 · Brand LE Raun · Category: Photoelectric Sensors
Range100 / 200 / 300 mm
SpotsSmall / large / strip
Response≤2 ms
ProtectionIP65
Overview
Background suppression is what makes a diffuse sensor usable on a real machine. Instead of measuring how much light comes back, the LFN-CX44 measures where it comes back from: the receiver is split into two elements, and the sensor switches only when the target is inside the set window and the background is beyond it. A black conveyor behind a white part, or a shiny machine frame behind a matte carton, no longer causes false triggers.Three spot shapes cover the usual cases. The small spot is for fine positioning of small parts; the large spot gives a broader detection area for irregular objects; the strip (bar-shaped) spot is for edge detection and for detecting objects that arrive at any orientation — a horizontal or vertical bar reads a wire or a thread regardless of how it is rotated.
Application scenarios
Edge detection with a bar spot
The strip spot reads the edge of a web or the gap between two panels.
Carton detection at a diverter
Ignores the steel frame behind the conveyor.
Glass and PCB presence
Detects transparent or reflective flat parts at a fixed distance.
Robotic bin picking verification
Confirms a part is in the gripper against a cluttered background.
Industries
- Packaging
- Electronics
- Logistics
- Automotive
Technical specifications
| Models | LFN-CX441N(P)DW / CX442N(P)DW / CX443N(P)DW (small spot) · LFN-CX441N(P)W / CX442N(P)W / CX443N(P)W (large spot) · LFN-CX441N(P)AW / CX442N(P)AW (strip light spot) |
|---|---|
| Detection method | Diffuse-reflective type (background suppression) |
| Detection range | 100 mm adjustable (CX441) · 200 mm adjustable (CX442) · 300 mm adjustable (CX443) · 100 mm adjustable (AW) |
| Sensitivity adjustment | Multi-turn potentiometer |
| Output mode | NPN or PNP open collector |
| Switch mode | L.on / D.on switchable |
| Response time | ≤ 2 ms |
| Light source | Infrared LED (650 nm) |
| Operating voltage | 12–24 VDC ±10% |
| Protection level | IP65 |
| Cable exit type | 2 m 4-core cable |
| Product application | Presence/absence detection for glass, PCB and other objects; suitable for complex application scenarios |
| Current consumption | ≤15 mA |
| Output current | ≤100 mA |
| Residual voltage | ≤1.5 V |
| Circuit protection | Short-circuit, reverse polarity, over-current |
| Ambient illumination | Incandescent ≤3,000 lux, sunlight ≤10,000 lux |
| Vibration / shock | 10–55 Hz 1.5 mm, 500 m/s² (X, Y, Z each 2 h) |
Dimensions
| Item | Value |
|---|---|
| Mounting holes | Ø3 mm, 26.5 mm pitch |
| Cable | 2 m, 4-core |
The 12 mm depth is what lets the CX44 sit between two plates of a fixture; the 26.5 mm hole pitch is the same as the LFD square body, so the two are interchangeable on a bracket.
Wiring & output
| Lead | Colour |
|---|---|
| 2 | Blue |
| 3 | Black |
| 4 | White |
| — | Grey (5-wire types) |
How to specify
- 01
Choose the detection mode
Through-beam for the longest range and the most reliable operation in dust; retro-reflective for one-sided wiring over a few metres; diffuse for colour-independent presence at short range; background suppression where the conveyor or the machine frame sits behind the target.
- 02
Check the target and the background
A diffuse sensor sees the target, not the gap: a dark matt object halves the range. Background suppression types are set by distance, so the background must be at least 20 % further away than the target.
- 03
Match the light spot to the part
A 10 mm spot on a 2 mm wire gives a weak, unstable signal; choose a lens with a small spot at the working distance, or switch to a laser type.
- 04
Decide the output and the housing
NPN for Asian PLC inputs, PNP for European; 4-wire when the PLC needs both states. Square plastic for general use, stainless for washdown, fibre-optic where the space is too tight.
Why this series
True background suppression
The window is set by distance, not by reflectivity, so dark or shiny backgrounds do not cause false switching.
Three spot geometries
Small, large and bar-shaped spots for fine parts, irregular parts and edges.
Multi-turn threshold
Fine adjustment of the 100/200/300 mm cut-off without a teach button.
Questions
What is the difference between the W, DW and AW versions?
The spot geometry: DW is the small spot, W the large spot, AW the bar-shaped strip spot. Ranges and electronics are the same.
Can it see through a transparent target?
It detects transparent objects by the light they return; for clear film on a clear liner use the capacitive label sensor instead.
Why does the range stop at 300 mm?
Background suppression needs a triangulation baseline; longer ranges need a time-of-flight or laser sensor.
Need a quotation for LFN-CX44 Background?
Send your application details or the guard opening dimensions and we will specify the right model and configuration for your machine.