The scanning depth of a barcode scanner refers to the effective distance range within which the scanner can clearly read barcodes, usually expressed as the minimum distance (near focus limit) and maximum distance (far focus limit). Depth of field is influenced by various factors, including scanning technology, barcode type, barcode density, and ambient lighting. Here is a detailed analysis:
1. Main Types of Barcode Scanners & Their Depth of Field
1.1 Laser Scanner
Typical Depth of Field:
Close range: 2–15 cm (high-density barcodes)
Long range: 30 cm to several meters (low-density barcodes, e.g., warehouse pallet codes)
Features:
Best for long-range scanning but sensitive to reflective surfaces.
Requires close proximity for high-density barcodes (e.g., small print on pharmaceuticals).
1.2 Linear Imager Scanner
Typical Depth of Field: 5–50 cm (common in commercial models).
Features:
Better at reading damaged or low-contrast barcodes but weaker in long-range performance than laser scanners.
1.3 2D Area Imager Scanner
Typical Depth of Field:
Close range: 1–30 cm (e.g., smartphone screen QR codes)
Long range: Industrial models can reach 1–3 meters.
Features:
Reads barcodes at any angle, including curved or uneven surfaces.
Supports both 1D and 2D codes (QR, Data Matrix).
1.4 Fixed-Mount Industrial Scanners
Depth of Field: Up to several meters (used in logistics sorting tunnels).
2. Factors Affecting Depth of Field
1.Barcode Density
Higher density (smaller bars) requires shorter scanning distance.
2.Scanner Resolution
High-resolution scanners read smaller barcodes but may reduce long-range performance.
3.Ambient Light
Strong light (e.g., sunlight) may interfere; some scanners have adjustable illumination.
4.Barcode Surface & Contrast
Reflective or low-contrast barcodes (e.g., gray-on-white) reduce effective scanning range.
3. How to Choose the Right Depth of Field?
Retail/Checkout: Short-range (5–30 cm) linear or 2D imagers.
Warehouse/Logistics: Long-range (1–3 m) laser or industrial 2D scanners.
Mobile Scanning: Short-distance (1–10 cm) wide-angle 2D scanners (e.g., for smartphone NFC scanning).
4. FAQ
Q: Why does a scanner sometimes need to be very close, and other times can scan from far away?
A: Depends on barcode density and scanner focus. Auto-focus scanners adjust automatically.
Q: Does depth of field relate to scanning angle?
A: Yes. Scanning at an oblique angle reduces effective depth; wide-angle scanners perform better.
