1. Project Overview

This solution deploys a high-precision machine vision inspection system for finished single-piece labels in the post-printing process. Equipped with high-speed industrial cameras for real-time image capture and intelligent inspection software, the system performs inspections for printing defects, barcode quality, variable data, label stains, missing print, die-cut misalignment, gold & silver hot stamping defects, mixed serial numbers and other issues. It achieves automatic identification and precise rejection of incorrect, missing and defective labels to control finished product quality and satisfy quality inspection demands for mass production of various labels.

2. Inspection Requirements and Performance Indicators

To fulfill full-range inspection requirements, the system is designed with the following core indicators:

Inspection Mode: Offline post-printing inspection (installed on inspection machines)

Applicable Materials: Coated art paper, white cardboard, grey cardboard, gold and silver cardboard.

Inspection Width: 300~350mm Operating Speed: Stable inspection speed with a maximum of 120 meters per minute Inspection Precision:

① Minimum detectable area for defects including missing prints and dirt spots: Front side ≥0.2mm²;

② Overprint deviation inspection: ≥0.2mm

③ Die-cut deviation inspection: ≥0.2mm

④ Scratches: Horizontal or vertical scratches with vertical width exceeding 0.2mm, horizontal width exceeding 0.15mm, length over 15mm and contrast above Grade 20 are detectable;

⑤ Partial color difference inspection ΔE≥2.5ΔELab

3. Full-Range Core Inspection Functions

3.1 Printing and Appearance Defect Inspection (Standard Fixed Data Labels)

The system compares samples with templates to detect surface physical and printing defects in real time:

Printed Texts & Patterns: Missing print, blocked plates, dirt spots, ink specks, scratches, ink splashes, knife lines.

Color Control: Supports online color difference monitoring and quantitative inspection of overall or local color deviation on printed products.

Post-Processing Structures: Die-cut misalignment, glue overflow, missing labels (broken strips).

Special Processes: Misaligned or missing gold & silver hot stamping, uneven varnish coating or surface scratches.

3.2 Variable Data and Barcode Compliance Inspection (Intelligent Variable Data Labels)

Carry out data comparison for high-standard labels used in pharmaceutical, food, electronics and other industries:

First-level quality grading for 1D barcodes and 2D QR codes;

Real-time decoding and reading of 1D barcodes and 2D QR codes;

Real-time online quality grading of barcode indicators such as contrast, modulation ratio and decodeability. Automatic waste rejection and alarm will be triggered if the grading result is lower than the preset standard.

3.3 Text Inspection:

Automatically identify and match text information stored in templates, including production date, batch number, shelf life, serial number and other contents. Verify text integrity and readability to avoid incomplete or broken characters.

Duplicate & Missing Code Prevention Mechanism: The system dynamically compares code packages and code pool databases. Interception will be activated once duplicate serial numbers or skipped serial numbers (missing codes) are detected during printing.

4. Hardware System Architecture

Cameras and light sources of the inspection system are intelligently configured to adapt to rigorous working conditions with high reflectivity and high running speed. Different hardware configurations can be customized to meet various customer demands.

4.1Industrial Cameras:

① Line Scan Camera: Suitable for high-speed, wide-format label inspection with continuous scanning imaging.

② Area Scan Camera: Suitable for single-piece label inspection or low-speed fixed-station inspection. Color / Monochrome Models: Color cameras are mandatory for inspections involving color difference and colored patterns; monochrome cameras deliver higher resolution for inspections focusing only on structures and barcodes.

4.2 Light Source System:

Labels are made of diverse materials. Dome shadowless lights are adopted for high-reflective materials to eliminate surface reflection; strip lights or ring lights are used for ordinary materials.

4.3 Image Capture Card & Processing Host:

Ensure real-time data transmission and processing under high-speed printing operation.

5. Closed-Loop Control and Defective Product Disposal Mechanism

Defect detection is only the preliminary step, while blocking defective products serves as the core of post-print inspection.

The inspection machine adopts a high-speed rejection mode: For cut single-piece labels under inspection, the system can link pneumatic blow-off valves or mechanical push rods to directly eject defective labels to the waste collection area.

6. Data Management and Upstream Process Tracing

Automatic Defect Classification & Statistics: The system automatically categorizes detected defects (e.g. 30% missing prints, 50% dirt spots, 20% low-grade barcodes) and generates pie charts and trend graphs.