Forem: zhu

How to choose between the four types of safety levels and the two types of safety levels for safety curtains?

zhu — Wed, 08 Oct 2025 12:18:35 +0000

1) Two Different Axes You Must Not Mix Up

Device Type (Type 2 / Type 4) describes the intrinsic fault-handling capability of the light curtain itself (per IEC 61496-1/-2 / GB/T 19436).
Required Performance for the whole safety function—your control system—is expressed as PLr (a–e) with design Categories Cat.1/2/3/4 under ISO 13849-1/-2, or as SIL 1–3 under IEC 62061 (use either ISO 13849 or IEC 62061, not both in parallel).
Placement distance is then set by ISO 13855 using the safety-distance equation S = K × T + C.

Rule of thumb: if your target is PLr d/e or SIL 2/3, a Type 4 curtain is not optional—it’s mandatory.

2) From Risk to Device Type: a Practical Decision Guide
Target Risk (from ISO 13849 assessment) Recommended Curtain Type Typical Control Architecture Notes
PLr a–b (low) Type 2 optional Cat.1/2 (single channel + self-check or periodic test) Light curtains are rare here; guards/limits often suffice.
PLr c (moderate) Prefer Type 2; upgrade to Type 4 if environment/impact is demanding Cat.2/3 (periodic test or dual-channel) Ensure short T, adequate S, and controlled false trips.
PLr d–e (high/very high) Type 4 required Cat.3/4 (dual channels, diagnostics, EDM) Presses, benders, robotic areas, cutting/clamping.
SIL 2–3 (IEC 62061) Type 4 required Meet PFHd objective Mirrors PLr d–e expectations.

How PLr is set (ISO 13849-1):

S (Severity): irreversible injury → d/e.

F (Frequency/Exposure): frequent or long exposure → higher PLr.

P (Possibility of avoidance): hard to avoid → higher PLr.

Fast track heuristics:

Stamping, bending, cutting, pressing, robot load/unload → Type 4 targeting PLr d/e.

Secondary guarding on conveyors or reduced-risk zones → may justify PLr c / Type 2, only after proving stop performance and trip robustness.

3) Why Type 4 Beats Type 2 at High Risk

Diagnostics & Redundancy: Type 4 has higher diagnostic coverage and redundancy; single-fault safe reaction is expected. Type 2 relies more on periodic testing and limited diagnostics.

Fault Handling: Type 4 tolerates interference, ageing, and misalignment better and fails safe.

Compliance Boundary: For PLr d/e or SIL 2/3, Type 2 cannot qualify.

4) Don’t Choose on “Type” Alone—Resolution & Height Matter

Resolution (beam spacing):

≤14 mm: finger protection (sealing knives, precision clamps)

30 mm: hand/forearm (robot infeed, conveyor nip)

40 mm: hand/arm (general industrial)

70–90 mm: whole-body (often better with safety laser scanners/fences)

Protective height: match the actual opening (typ. 450–1200 mm).

Environment: IP rating (washdown → IP67), steam/reflectivity immunity; angle the curtain and add dark backplates near shiny films if needed.

5) Safety Distance (ISO 13855)—Non-Negotiable

Formula: S = K × T + C

K (approach speed for upper limbs): 1600 mm/s (typical)

T (total stop time): safety relay/controller + drive/brake/valve

C (offset): 8 mm for fingertips (+ any encroachment allowance)

Example (heat-sealing knife): measured T = 0.12 s → S = 1600 × 0.12 + 8 ≈ 200 mm.
Install at ≥220 mm to cover tolerance and alignment drift. Use a stop-time meter, record the worst case, label the frame, and archive—this is part of ISO 13849-2 validation.

6) Control Architecture for High-Risk Functions (the “standard kit”)

OSSD1/OSSD2 dual channels → PL e safety relay or safety PLC.

EDM monitors contactor welding; no reset if welded.

Manual reset (no automatic restart): after beam restoration, a person must confirm.

Muting/Blanking where product must pass: use directional + time-window logic—let product through, not people.

HMI = status/diagnostics only; do not implement safety in a standard PLC.

7) Quick Prescriptions by Scenario

Press/brake/molding closure/cutting: Type 4 + PLr d/e, 14 or 30 mm, manual reset + EDM.

VFFS/heat-seal/packaging knives: reflective + washdown → Type 4, 14 mm, compute S per ISO 13855; apply fixed/floating blanking if fixtures intrude.

Robot load/unload, guarded entries: Type 4, 30–40 mm; for area/whole-body, consider safety laser scanners or interlocked doors.

General conveyors/low-risk portals: possibly PLr c / Type 2 after proof of stop time and false-trip control.

8) Selection & Validation Checklist (follow this to the letter)

Risk assessment → set PLr (or SIL).

Pick device type: if PLr ≤ c and conditions are controlled → Type 2 may fit; PLr ≥ d → Type 4 only.

Choose resolution/height for the body part at risk.

Measure T, compute S, label and archive per ISO 13855/13849-2.

Engineer OSSD/EDM/manual reset/muting; draw the circuit.

Check environmental robustness (IP, reflection, steam, vibration).

Validate: worst-case stop time, 14/30 mm test-rod intrusion, EDM welded-contactor test, restart test.

Document: risk report, calculations, schematics, validation records, maintenance plan.

9) Executive Takeaway

If potential harm includes severe injury, amputation, or operators are frequently and unavoidably exposed, go straight to Type 4 and design the function to PLr d/e (or SIL 2/3).
Only when a thorough assessment clearly places the task at PLr c and the application conditions are tightly controlled should Type 2 be considered.

What is Lidar Scanner

zhu — Thu, 18 Sep 2025 02:19:45 +0000

Understanding Lidar Scanner Technology
Lidar Scanner technology revolutionizes spatial measurement through laser-based remote sensing. By emitting laser beams and analyzing their reflected signals, a Lidar Scanner determines distance, shape, and position with millimeter-level precision. The term "Lidar" stands for Light Detection and Ranging, a method that generates detailed 3D environmental models through point cloud data. This innovative Lidar Scanner technology serves critical functions across autonomous driving, geographic mapping, architectural planning, and environmental monitoring.

Working Principle of a Lidar Scanner
The core operation of a Lidar Scanner relies on Time of Flight (ToF) measurements or phase difference analysis. When a Lidar Scanner emits short laser pulses, these beams travel to target objects and reflect back to the sensor. Sophisticated algorithms calculate distances by measuring light speed and return time intervals. Modern Lidar Scanners incorporate rotating mirrors or MEMS (Micro-Electro-Mechanical Systems) technology to achieve 360° scanning coverage, enabling comprehensive spatial data collection. The resulting high-density point clouds form the foundation for generating accurate 3D models of scanned environments.

Technical Features of Modern Lidar Scanners
High Precision Sensing
Millimeter-level resolution enables detailed mapping
Multi-beam systems capture complex geometries
Advanced Operational Capabilities
All-weather performance with infrared lasers
Low-light operation for 24/7 functionality
Versatile Applications
Environmental monitoring and forestry management
Robotic navigation and obstacle detection
Data Processing Requirements
High-performance computing for point cloud analysis
Advanced algorithms for real-time object recognition

Lidar Scanner Applications
In autonomous vehicles, a Lidar Scanner provides real-time environmental perception by detecting pedestrians, vehicles, and road obstacles with unparalleled accuracy. Construction professionals utilize Lidar Scanners for creating as-built documentation and 3D building models that streamline design processes. Natural resource management employs Lidar Scanner technology for forest canopy analysis and terrain mapping, enabling precise biomass calculations and flood risk assessment. Industrial facilities implement Lidar Scanners for indoor robot navigation and safety monitoring.

Advancements in AI and sensor miniaturization continue to enhance Lidar Scanner capabilities. Solid-state Lidar technology eliminates moving parts, increasing reliability while reducing costs. The latest Lidar Scanner models feature expanded field-of-view and higher angular resolution, improving performance in challenging environments. As Lidar Scanners become more compact and affordable, integration into consumer electronics and smart city infrastructure accelerates. Industry forecasts predict a $1.5 billion valuation for Lidar in construction alone by 2030, reflecting the growing dominance of this revolutionary scanning technology.

DAIDISIKE Brand and LiDAR Product Overview
DAIDISIKE’s LiDAR is developed and manufactured with a focus on high performance and reliability. DAIDISIKE is a leading manufacturer specializing in the research, development, and production of high-performance, reliable LiDAR scanners. Our DLD series LiDAR products have been successfully deployed in the Chinese market for over a decade, earning widespread trust for their proven quality and performance through real-world applications.

We have introduced a range of LiDAR models, including:

DLD05A3-3N: 5-meter detection range, ideal for high-precision, short-range detection scenarios.
DLD20A5-5N: 20-meter detection range, suited for mid-range environmental monitoring and navigation.
DLD30T-5N: 40-meter detection range, designed for long-range applications in complex environments.
5JPTG/10JPTG: Newly developed models with 5-meter and 10-meter detection ranges, optimized for performance and cost-efficiency.
100-meter LiDAR: Coming soon, stay tuned for updates.
DAIDISIKE’s LiDAR scanners integrate obstacle avoidance, measurement, and real-time data transmission capabilities, enabling real-time data reception and signal alerts via computer. Known for their high precision, rapid response, and reliable performance, our products are widely used across various industries.

Application Scenarios
AGV/AMR Autonomous Mobile Robot Navigation and Obstacle Avoidance: Supports 2D planar scanning, obstacle avoidance with deceleration, virtual walls, and safety zone switching, configurable via computer. Ideal for intelligent warehousing and factory logistics automation.
Forklift and Tractor Collision Avoidance: Actively monitors safety zones around vehicles during low-speed operations, turns, or in blind spots, providing multi-range safety protection to reduce risks in mixed pedestrian-vehicle environments.
Industrial Robot Workstation Safety: Establishes multi-level safety zones around robots, triggering deceleration or shutdown upon intrusion, with optional alarm light integration for enhanced safety in human-robot collaborative settings.
Logistics Sorting and Conveyor Line Protection: Detects personnel intrusion and intercepts restricted areas along conveyors or sorting machines, minimizing accidental contact or injuries.
Smart Access Control and Entry Management: Provides presence detection and anti-pinch/anti-collision features for gates, rolling shutters, and retractable doors in mixed pedestrian-vehicle scenarios.
Parking Lot and Toll Booth Vehicle Profiling: Confirms vehicle presence, identifies dimensions and positioning, and optimizes lane throughput efficiency.
Construction Site Perimeter Safety: Dynamically monitors and alerts for high-risk areas such as edges, lifting zones, or hazardous work zones, enhancing on-site safety compliance.
Volume and Contour Measurement: Measures 2D contours and occupancy of pallets, packages, or boxes, facilitating automated sorting and billing on production lines (requires coordination with clients on operational details).
Elevator and Automatic Door Anti-Pinch Detection: Detects people or objects in door zones to reduce the risk of pinching, improving passage safety and experience.
Rail and Port Vehicle Safety Assistance: Performs low-speed area scanning for bridge cranes, yard vehicles, or rail vehicles to minimize blind spot risks.
Crowd Management in Scenic Areas and Venues: Monitors crowd density and triggers congestion alerts to support operational scheduling.
Agriculture and Specialty Vehicles: Enables forward obstacle avoidance and edge detection for orchard vehicles, sanitation trucks, and construction vehicles in complex terrains.

Product Advantages
High-Precision Measurement: Delivers millimeter-level accuracy for reliable data.
Real-Time Data Transmission: Supports fast data transfer for real-time monitoring in dynamic environments.
Versatile Applications: Offers multiple detection ranges to suit short-, medium-, and long-range scenarios.
Robust and Durable: Rigorously tested for stable, long-term performance in challenging environments.
Easy Integration: Features standard interfaces for seamless integration with various devices and systems.

Why Choose DAIDISIKE?
DAIDISIKE’s LiDAR solutions are not only technologically advanced but also tailored to meet customer needs, offering customized solutions backed by a decade of market-proven reliability. Our products are widely adopted in cutting-edge fields such as smart manufacturing, autonomous driving, and smart cities. By choosing DAIDISIKE, you gain access to high-performance LiDAR products and dedicated after-sales support to ensure your project’s success. We welcome inquiries for OEM and ODM partnerships. For more LiDAR demonstration videos, please click on our YouTube videos: 1，Computer operation demonstration ; 2，3D animation demonstration.

Light Barrier (Safety Light Curtain): Working Principle, Types

zhu — Sun, 14 Sep 2025 04:51:34 +0000

photoelectric_ safety barrier / _safety light barrier
Updated: 2025-09-08 · DAIDISIKE
In industrial machine guarding, “light barrier” usually refers to a safety light curtain—an array of infrared beams forming a protective field. This article gives a practical, standards-oriented explanation you can use on real machines: definition, how it works, Type 2 vs Type 4, safety distance, and a selection workflow for presses and robot cells.

Safety light curtain working principle illustration
Safety light curtain (light barrier) — principle overview
On this page
Working Principle of Light Barrier (Safety Light Curtain)
Types of Light Barrier (Safety Light Curtain)
Guide to Machine Protection with Light Barriers
FAQ
Working Principle of Light Barrier (Safety Light Curtain)
A safety light curtain uses modulated infrared photoelectric detection. When any beam in the protective field is interrupted, the system switches its safety outputs, stopping hazardous motion via a safety relay or a safety PLC.

Signal flow: emit IR → receive → detect interruption → switch OSSD → machine stop
Working principle of safety light curtains – step 1
Working principle of safety light curtains – step 2
Working principle of safety light curtains – step 3
Main components
Emitter: An array of IR diodes fires beams in a timed sequence. The light is modulated (tens of kHz) so ambient light is rejected.
Receiver: A matched array of photodiodes/phototransistors reads each beam in order and reports any loss.
Control/Safety Output Module: Processes receiver data, runs internal diagnostics, and drives OSSD outputs to the machine’s safety circuits.
Key technologies for reliability
Modulation & optical filtering: Frequency-coded pulses and electronic filtering reduce false trips from lamps/sunlight.
Redundant architecture & self-tests (Type 4): Dual-channel electronics (often dual MCUs) cross-monitor critical paths. Any internal fault forces a safe state.
OSSD safety outputs: Modern curtains provide two independent PNP sourcing outputs. Safe/clear state = high; interruption or fault = outputs switch off (low). Cross-short and wire-break detection is built-in. Always follow the product datasheet if NPN variants are used.
Installation & maintenance essentials
Precise alignment & rigid mounting (use the built-in alignment indicators).
Calculate safety distance so the machine fully stops before access is possible.
Daily functional test: Before each shift, block with a test rod and confirm stop.
Keep optics clean: Oil and dust reduce margin; clean windows regularly.
Wire to safety circuits only: Route OSSD directly to a safety relay/PLC, not general I/O.
DAIDISIKE notes. DQC/DQE/DQT/DQA/DQO/DQR/DQL/DQM/DQS/DQB/DQZ series use wired synchronization for robust signal timing. Use shielded cables; in noisy environments bond the shield per manual (0V/PE as specified) to avoid ground loops. MK/JER series support optical sync for short opposed distances (≤ ~6 m) to simplify cabling.
Types of Light Barrier (Safety Light Curtain)
Safety light curtains can be compared from two angles: installation form (how beams traverse the area) and safety performance (Type 2 vs Type 4 design targets based on ISO 13849 principles).

Feature Through-beam (opposed units) Single-side with safety mirrors / retro-reflective solutions Type 2 Type 4
Working principle Dedicated emitter ↔ receiver across the opening One active side; beam path redirected via safety mirrors / certified reflectors Basic fault checks at start/restart Continuous diagnostics & dual-channel architecture
Range & accuracy Long range, high stability, small-object detection Medium range; care with mirror contamination/alignment For lower-risk applications For higher-risk zones
Installation Needs mounting on two sides Single-side mounting; good for tight spaces or multi-side perimeters PL up to ~c / SIL 1 (typical) Targets PL e / SIL 3 (Cat.4 designs)
Cost Higher (two active units) Lower hardware; mirrors need upkeep Lower Higher
Typical uses Presses, shears, large machine openings Confined cells, perimeter guarding with L/U/□ beam paths Choose based on formal risk assessment (PLr)
Key performance parameters
Resolution (beam spacing): 14 mm (finger), 30 mm (hand), 40–200 mm (body/area).
Protection height & operating range.
Response time: < 10 ms.
Environmental ratings: IP, vibration, oil mist, EMC.
Mounting solution 1
Mounting solution 2
Mounting solution 3
Mounting solution 4
Guide to Machine Protection with Light Barriers (Safety Light Curtains)
Resolution vs protection objective
Protection objective Recommended resolution Machine examples Notes
Finger 10–14 mm Small presses, assembly jigs, press brakes 14 mm is the global mainstream for finger protection; 10 mm for higher protection.
Hand 20–30 mm Power presses, feed areas of machine tools 30 mm widely used; prevents palm/wrist access.
Body / area 40–200 mm Packaging lines, logistics cells, access gates For area isolation or entry detection.
Special cells Customized Robot welding, spray booths, test rigs Usually multi-side guarding with mirrors + muting/blanking.
Resolution vs protection objective illustration
Safety distance quick guide (ISO 13855):
Measure total stop time T (light curtain + logic + machine).
Use approach speed K from the standard (e.g., 2,000 mm/s for hand/arm).
Compute S = K × T + C (C = reach-over constant by resolution).
Mount the light curtain at distance ≥ S from the hazard.
Verify with a test rod and record results in the maintenance log.
Get a light barrier selection sheet Type 4Press brake
FAQ
Is “light barrier” the same as “safety light curtain”?
In industrial safety, they are used interchangeably. Check the Type rating and confirm the design meets the required Performance Level (PLr) for your machine.

Type 2 vs Type 4 — how should I choose?
Decide by risk assessment (PLr). Type 4 has dual-channel diagnostics aimed at PL e/SIL 3 architectures for higher-risk zones (e.g., presses, robot cells). Type 2 suits lower-risk tasks.

What is an OSSD safety output and why are there two channels?
OSSD are self-monitoring safety outputs. Two independent channels let the safety relay/PLC detect shorts, breaks, and faults. If any issue occurs, both channels switch off to force a safe stop.

Should I use PNP or NPN outputs?
Use what your safety relay/PLC input expects. PNP (sourcing) is the global mainstream for OSSDs. If using NPN, ensure the entire safety circuit is designed for sinking logic and maintains diagnostic coverage.

Do I need a safety relay or can I wire to a normal PLC?
Use a certified safety relay or a safety PLC. General PLC inputs are not safety-rated and cannot guarantee the required Performance Level, even if they read the signals.

14 mm vs 30 mm — which resolution should I pick?
14 mm targets finger protection; 30 mm targets hand/palm protection. Choose by the smallest body part that must be prevented from entering the hazard and the machine opening size.

Video demonstration of safety light curtains
Video demonstration of safety light curtains

Video demonstration of DQL detection series
Video demonstration of DQL detection series

3D animation demonstration of light curtains
3D animation demonstration of light curtains

DAIDISIKE DQT Type 4 safety-rated light curtain
DQA Series DQC Series DQB Series DQO Series DQR Series DQL/DQM Series DQE Series DQSA Area Series DAIDISIKE CE Certificates Safety Rating Certificates More Product Certificates

Author: DAIDISIKE Engineering Team · Last reviewed: 2025-09-08 · Contact: About & Team
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