A typical inspection system can be broken down into key functional elements combined to form your solid state machine. This article examines these key functional components to give the customer a greater understanding of each element.
Understanding the key components to use in your inspection system
Aristotle put on his engineering hat and was looking at designing vision systems when he said the above. Let's look at the key elements of the line scan inspection system.
At OneBoxVision we break the inspection system down into functional elements. A solution can be split into the following elements.
- The imaging system - this includes cameras, optics, illumination and of course the product itself.
- The processing system - this is the PC or embedded hardware along with the software to analyze the images.
- The output system - this includes the display for the operator, alarms to be initiated, the parent machine interface and the data to be output.
The imaging system
Typically the imaging systems represents 50% to 60% of the cost of an inspection system and is often the least understood by the buyer. When an application is analyzed, a particular camera is selected. The key items now when choosing the brand is its capability and if it conforms to standards.
The standards most commonly referred to are:
- Camera Link, a high-speed serial digital bus designed specifically for machine vision cameras.
- The USB 3.0 standard, also known as SuperSpeed USB, is the second major revision of the USB standard for computer connectivity.
- Gigabit Ethernet is a new camera bus technology for machine vision systems. With relatively high bandwidth, long cable lengths, and wide usage in the consumer and industrial applications, Gigabit Ethernet shows promise for security and long-distance vision applications.
- New and faster cameras are now using CoaXPress, an even higher speed version of CamLink.
Lower cost solutions prefer Gigabit Ethernet, while the faster more complex applications tend to be CamLink, either works. What is key is that you understand the interface that is used and that there's no proprietary hardware components used.
A lens will determine the working distance. If there is a small envelope to install a system, an integrator may choose a wide angle lens. The trade-off is that there will be imaging problems on the edge of the field of view. This can mean that defects such as holes cannot be classified. Understand which lens is used, the trade-offs and why it was chosen.
Lighting usually is the most expensive element of a web or sheet inspection solution. Depending on the substrate and defects, there can be multiple lights used to image a product. The key items to understand are the cost of replacement, if the light has enough power for the variety of substrate used and also if there's any maintenance.
The key facts to be determined when choosing the imaging system:
- Make and type of camera, and what standards it uses.
- Is there any special boards that cannot be purchased off the shelf?
- The type of lens and why that one was chosen?
- The lights used, the output and required maintenance.
The processing system.
The processing system for web inspection normally includes a highend workstation, frame grabbers if it is a CamLink camera, an I/O input/output card and the software to process the images.
The key facts to be determined when choosing the processing system:
- The specification of the PC
- Make and type of frame grabber
- I/O Module manufacturer
- Operating system and if the application software can be upgraded
The output system.
The outputs include the operator display and how defects are shown. So make sure you understand what type of display is provided. It's no good if you are displaying a postal stamp image of a defect on a tiny LCD display. Monitors should be wide screen, high resolution, with graphical overlays to highlight the position of defects.
Look at the best solution for your environment and process when choosing output equipment. Tree lights are only useful if there is not 10 of them already surrounding the operator. Buzzers can be annoying if there are lots of defects. Make sure that the software can be configured to output and drive outputs depending on class and number of defects. For roll to roll operations, marking systems and tag inserters can be used.
The key facts to be determined when looking at the output system:
- Operator display
- Alarming systems
- Marking systems and tag inserters for roll to roll operations
- Can the software be configured for intelligent decisions when it comes to outputs