Why Inspection Accuracy Depends on System Integration

Automatic Inspection Systems are an integral part of today’s Pharmaceutical Manufacturing process for maintaining Tablet/Capsule Quality. These systems perform the last quality check before products go to the patient. With increased regulatory requirements and faster production rates, accurate inspections are now required-not just recommended.

There is a false belief within the Industry that a High-End Camera will provide the most accurate inspections. Cameras do contribute to the overall system, but there is a lot more than just a camera to create an Integrated System known as the “Inspection Triangle”. The Inspection Triangle consists of Lighting, Cameras, Software, etc. Together, these components determine the overall inspection performance of a tablet/capsule inspection system.

Accura Pharmaquip takes a holistic approach to designing an inspection system because each component cannot produce reliable results independently. The remainder of this article discusses how lighting, cameras, and software all interact with each other in a tablet/capsule inspection system, and why it is the integration of these components, not just individually, that provides consistent results.

Overview of an Automatic Tablet & Capsule Inspection System

The automated tablet and capsule inspection system utilizes a standardized process to optimize both the speed and accuracy of each product inspected at the same time, utilizing consistent repeatable processes. The general flow of an automatic tablet/capsule inspection system involves:

• Product preparation: Tablets/Capsules are presented to the system individually with their orientation, then moved into the inspection area.
• Image capture: Images are captured using cameras as the tablets/capsules move through the inspection area.
• Decision making based on image analysis: All of the images taken are analyzed by computer software to determine if they will be accepted or rejected.

Lighting and camera systems, as well as software applications, do not exist as separate processes in an automated system, but work together as a single unit to enable accurate inspection. Properly functioning lighting allows for defects to be visually identified; properly operating cameras allow for usable data to be collected; and properly functioning software allows for the interpretation of that data. Thus, it is essential for all of the various component parts of an automated system to function as one synchronized unit when performing high-speed pharmaceutical inspections.

Role of Lighting in Inspection Systems

Why Lighting Is the Foundation of Accurate Inspection

Lighting is frequently underappreciated, but it is one of the primary factors for determining if you will see an issue at all. The best camera available has no chance to spot an issue that poor lighting prevents from being seen.

Poor lighting can cause:

• False rejects due to shadows or glare
• Issues may be missed because there is inadequate contrast
• Results are inconsistent from batch to batch

A well-lit area provides enough contrast to show where your product meets and where it doesn’t meet the specifications of the product; this forms the base upon which the rest of the inspection equipment functions.

Types of Lighting Used in Tablet & Capsule Inspection

There are a variety of ways to view a defective product depending on the type of defect it has:

• Backlighting is best suited for viewing cracks, pinholes, deformation in shape, and variation in transparency.
• Front lighting is ideal for viewing defects that occur on the surface of products, such as staining, chipping, color variation, embossing problems, etc.
• Diffuse lighting will reduce the amount of reflection and glare that occurs from the product being viewed, particularly useful when viewing glossy or coated tablets.
• Directional lighting will accentuate the texture and surface irregularities of the product.
• Multiple-angle lighting will allow you to view all sides of a product at 360 degrees, which is important when viewing capsules and/or complex shapes of a tablet.

Lighting Challenges in Pharma Inspection

Pharmaceutical products create a number of unique lighting issues:

• Reflective coatings on tablets
• Variable colors due to natural variations in each batch of tablets
• Transparent and/or translucent capsule fill
• Powder/dust contaminating images and reducing clarity

Designing lighting for these challenges will require specific designs based upon the characteristics of the pharmaceutical product being inspected, as well as the inspection objective.

Role of Cameras in Inspection Systems

Camera Function in Automatic Inspection

High-resolution images are captured by cameras at very high-speeds; some exceeding thousands of products per minute. For this reason, they need to be accurately synchronized with product movement and lighting pulse timing so as to prevent blurring from the motion of the product being inspected and other distortions in the images taken.

Types of Cameras Used

Inspection systems commonly utilize the following camera types:

• Static or indexed inspection area scan cameras
• Line scan cameras for continuous production at high speed
• Capable of capturing high-speed tablets and capsules, high-speed cameras
• Color cameras for detecting color, shading, etc.
• Monochrome cameras for greater contrast and dimension accuracy

Key Camera Parameters Affecting Inspection

Camera Parameters that are critical in determining an effective inspection include:

• Resolution: Resolution determines how small a defect can be detected.
• Frame Rate: Frame rate must equal line speed for accurate inspections
• FOV (Field of View): FOV provides coverage of the inspection area with minimal loss of detail in the image.
• Dof (Depth of Field): Dof allows for consistent focus on all parts of the inspected products with varying dimensions
• Pixel Accuracy: Pixel accuracy will directly impact the ability to measure accurately

Using a camera that is not suitable for inspecting products can result in either missing defects or excessive false rejects, independent of lighting and/or software capabilities.

Role of Software in Inspection Systems

Image Processing and Defect Detection

Raw images are transformed by inspection software into actionable decision-making via a process of:

• Normalization and image enhancements
• Feature extraction with edge detection
• Comparisons against reference standards and tolerance levels

Rule-Based vs AI-Based Inspection Software

• The rule-based system is transparent and predictable in its algorithmic and threshold approach
• The AI and deep learning systems are superior to traditional systems when it comes to finding variable and complex defects, as well as improving the overall false reject rate of the system

It is common practice today for modern systems to use a combination of both rule-based and AI systems in order to find an optimal balance between being able to be explained and having a high level of performance.

Decision-Making and Machine Control

Software handles:

• Accept/reject logic
• Defect categorization and statistics
• Feedback loops to upstream or downstream equipment, enabling process optimization

How Lighting, Cameras, and Software Work Together

System Synchronization

A synchronized system is the key to true inspection accuracy:

• Pulsed lighting that is in sync with the shutter speed of the camera
• Triggering an image using software in real time
• Absence of any delay during production

Example: Detecting a Tablet Surface Defect

• Step 1: Light illuminates the slight surface stain.
• Step 2: The camera takes a clear image of the contrast of the tablet at exactly the right time.
• Step 3: Software finds the flaw, identifies it as a flaw, and sends it for rejection.

If any step is out of sync, then the stain will be missed.

Importance of System Calibration

An integrated inspection system requires continuous calibration:

• Lighting intensity and angles
• Camera alignment and focus
• Software threshold tuning

Continuous calibration is necessary for consistency throughout shifts and batches.

Common Integration Challenges and Solutions

Common problems are:

• Falsely rejected parts as a result of inconsistent lighting
• Missed defects resulting from a bad camera choice
• Software misclassifying images due to poor image quality

The answer is to use an integrated approach to designing the overall system so that all of the pieces work together instead of each piece working independently.

Compliance and Data Integrity Considerations

Compliance through integrated inspection systems can be achieved as follows:

• GMP-compliant inspection results are consistent and repeatable
• Audit trail and image capture are available
• The systems comply with 21 CFR Part 11 and ALCOA+

The software used to provide compliance reporting, data integrity, and traceability represents an important part of compliance.

Future Trends in Inspection System Integration

Emerging trends:

• Intelligent adaptive illumination and camera settings that are AI-driven
• Inspection algorithms that self-learn
• Smart inspection systems that align with the concept of Pharma 4.0
• Real-time Quality Intelligence (QI) through integration with MES and SCADA platforms

In addition to other areas of inspection technology, these emerging trends demonstrate the increasing importance of system-level integration.

Conclusion: Why Balanced System Design Matters

Accuracy in inspections for tablets and capsules is achieved by combining a series of components, including light, cameras, and software, with no single component or failure capable of causing an overall loss of inspection accuracy. A failure in one will cause a total system failure.

To sum it up, the performance of an inspection system is only as good as its weakest link. Manufacturers who use a combined system of inspection design may be able to provide their products with quality assurance, regulatory compliance, and long-term cost savings; principles that are used at Accura Pharmaquip to develop our pharmaceutical inspection systems.