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Safety light curtain definition
A safety light curtain is an opto-electronic guard that throws a wall of invisible beams between a transmitter and a receiver. When anything breaks a beam, the system cuts its OSSD (output signal switching device) and tells the machine to stop safely. No sleeves near pinch points, no guessing. That’s the core idea.
In short: beams form a protective field; interruption = safe stop. Simple, fast, repeatable.
How a safety light curtain works (OSSD, transmitter/receiver)
Transmitter → emits a matrix of infrared beams.
Receiver → watches each channel.
Controller/relay → turns OSSD off the moment any beam is blocked or a fault is detected.
Self-diagnostics → internal faults force a safe state. No “half-safe.”
OSSD safety outputs
OSSD channels come in pairs and are monitored for shorts, cross-faults, and timing. If wiring goes bad or a contactor welds, the system doesn’t pretend. It trips. That’s why EHS teams trust them on high-risk equipment.
Protection resolution: 14 mm vs 30 mm
Resolution equals the smallest object the curtain can “see.”
14 mm → finger-level protection near the hazard.
30 mm → hand-level guarding with a bit more standoff. Higher resolution lets you mount closer to danger points, which keeps takt time and ergonomics happy.
Type 2 vs Type 4 safety light curtain
You’ll see Type 2 and Type 4 a lot. Rule of thumb: when risk is serious or integrity must be high, pick Type 4. It’s built for higher performance levels and tougher diagnostics. Type 2 fits lower-risk stations and non-critical tasks. Dont over-spec for a light stacker, don’t under-spec for a press line.
ISO 13855 safety distance (S = K×T + C)
A curtain isn’t magic. You must place it far enough from the hazard so a person can’t reach in before motion stops. Use the ISO S = K×T + C idea:
K = approach speed (hand/arm or walking).
T = total stop time (machine + control + curtain response).
C = reach-in allowance tied to resolution and mounting.
Measure real T on your machine (brakes, valves, drives). Add the control and light-curtain response. Then mount at the calculated S. If in doubt, be conservative.
Muting, blanking, and EDM
Muting lets pallets or totes pass through automatically (e.g., triggered by two mute sensors in sequence) while still stopping for a person.
Blanking masks fixed beams (or allows limited drift) when fixtures or grippers must live inside the field.
EDM (external device monitoring) checks that your contactors and safety relays actually drop out—no welded contacts hiding in the background.
Real-world use cases and pain points
Packaging & logistics conveyors. You want zero tailbacks and zero bypassing. Use muting at infeed/outfeed so cartons glide through but a human step halts motion.
Presses and metal forming. High energy, short cycle times. Use Type 4 with tight resolution near the die. Validate stopping time after every maintenance job.
Injection molding & die-casting. Fixed tooling everywhere, doors that operators love to wedge open (sigh). Add blanking for tie bars or end-of-arm tooling; combine with interlocks on gates.
Robotic cells. For compact cells, a curtain beats a big fence when you need access. Add multi-sided access protection for corners and teach points.
Woodworking & panel lines. Dust, vibration, random stock sizes. You’ll want robust alignment and sometimes waterproof housings for wash-down or wet cuts.
Electronics assembly / 3C. People work close; fingers, not just hands, are at risk. Go 14 mm resolution and keep the distance tight for good ergonomics.
Battery, pharma, food & beverage. Hygiene rules and frequent changeovers. Quick-mount brackets, IP ratings, and auto-alignment save your sanity.
Product categories mapped to needs (NEW STAR OEM)
We serve machine builders, EHS/safety managers, production leads, maintenance teams, and procurement. The short list below connects typical problems to the right family. Click through for NEW STAR product lines and OEM/ODM details:
NEW STAR is a one-stop machine safety sensors manufacturer. ISO9001 factory. Type 4 options. We handle OEM/ODM from sample to scale, with custom heights, brackets, cables, and field services when you need them.
Quick argument table (for your safety review)
Claim
Why it matters
Practical check
Keyword
OSSD turns off on beam break or fault
Ensures a safe stop even if wiring/components fail
Risk assessment first. Define required Performance Level. If it’s severe harm with frequent exposure, you probably land on Type 4.
Measure stop time. Capture machine stop, drive/valve delay, relay, and curtain response. Add them up.
Calculate safety distance. Use the ISO idea and mount at or beyond S. Re-measure after any change.
Mount for reality. Avoid reflections; plan for forklift hits; add guards at the bottom so no one crawls under.
Configure functions. Muting sensors, blanking windows, EDM circuits. Document the logic so maintenance knows what’s normal.
Train operators. Show them what the indicator LEDs mean. No tape-over hacks.
Test routinely. Daily function tests, and periodic stop-time validation. Log it. Teh audit will ask.
How it works in practice (three short scenarios)
Conveyor in a packaging hall. Two mute sensors before the curtain see a carton arrive in sequence. The system temporarily allows passage. A person steps in? Different height/sequence, so OSSD drops and the conveyor halts. Throughput stays steady; people stay intact.
Press brake with finger guarding. We choose a 14 mm curtain, measure stopping time, compute S, mount close. EDM watches the dual contactors. A welded contact gets flagged at start-up instead of mid-shift.
Robot cell with changeovers. Fixtures intrude into the field—use fixed blanking on those beams only. During teach mode, add a reduced-speed hold-to-run so the curtain isn’t your only guardrail.
Buyer notes for engineers, EHS, and procurement
Engineers: think wiring simplicity, diagnostic depth, IP ratings, and the bracket kit that aligns in minutes—not hours.
EHS & safety managers: ask for the risk assessment, validation sheet, and stop-time records. Make these routine.
Procurement & compliance: look for Type 4 certification, ISO9001 factory controls, and OEM/ODM ability so future lines match this one. Fewer vendors, faster spares, less downtime.
Why NEW STAR (quick but real)
We build safety & measurement light curtains, laser scanners, mats, and interlock switches under strict quality systems. If you need custom lengths, odd mounting, non-standard cabling, or batch wholesale, we’re set up for it. You bring the line layout; we help you pick the right curtain, mount it to spec, and validate. No fluff—just gear that guards people and keeps production moving.
