The goal of this document is to review the inspection system technically and to identify future support issues. The diagram above shows the 4 key areas that are then surveyed in detail below.
- Camera system
- LED Lighting system
- Image processing system
CameraPlease define the camera model. The common models of line scan cameras are:
- Teledyne Dalsa
What is the model of camera and what type of sensor does the camera use?
Not all sensors are created equal. There are color cameras that are Trilinear (RGB) , optical three chip using prism splitter, and bilinear sensors that use the Bayer method. Most are trilinear. The prism splitter was superior technology years ago but the filter technology has caught up to equal color fidelity. The bilinear method use a two chip solution that reduces costs and is not suitable for high end imaging.
What is the sensor size(s) and line rates?
This will determine the resolution of the system.
What is the number of pixels per camera and the actual pixel size?
The larger the pixel size the better the quality.
What interface does the camera use?
The standard interfaces for commercial off the shelf cameras are CamLink, USB3, GigE and
Coaxpress. The dominant standard for high speed line scan cameras is Camlink. See https://en.wikipedia.org/wiki/Camera_Link . There are three configurations. High speed color cameras will use the medium and full configurations.
Name two other cameras that can be used in place of the camera chosen?
This is key to stop obsolescence. If adhering to standards there should be at least two others cameras commercially available that are capable of the same function.
Is there any special feature that you use that with the camera chosen?
If a vendor is using some special feature that is unique to that camera, then it will not be possible to use an alternative even if there is a drop in that looks the same.
Can this camera be purchased from a local distributor and expected list price?
All commercial off the shelf components have global distribution channels. Typical prices for color cameras range from $4,500 to $5,500. Remember that cables, lenses PSUs are extra.
There is no industry standards when it comes to LED illumination. However there are common features that are important. The key vendors for line scan illumination are:
- Advanced illumination
Are the lights commercial off the shelf?
The first step is to determine if the lights are built by the inspection system provider or commercially off the shelf.
What are the cooling options for the light?
Typically commercial off the shelf solutions offer a variety of cooling options. The first is passive, second is active air (fans) and third is water. It is important to know that you have options as sometimes you may need different solutions based on geography and environment.
Does the light have overdrive control?
Modern LED systems need to have overdrive control and thermal monitoring to avoid burnout.
How many lights will you use in each application?
If inspecting metallic inks, foil and clear film, then there should be three lights. One for standard
imaging, one for foils and a back light. Sometimes a white background is used instead of a back light, this can cause issues as it gathers dust.
What is the interface if any to control the lights?
There is no industry standard for controlling LED lights. Interfaces can vary from using a digital analog signal - say 0 to 24V , or a serial interface. Modern systems tend to have a TCP/IP interface.
If there is an interface, will the system operate without it?
Sometimes systems auto adjust the intensity of the light to compensate for speed or to guarantee
repeat-ability. This is not a problem, but it is important to know because it means that the lighting system and this model of light must be in place for the system to run.
If there documentation to describe this interface?
If the vendor goes out of business, this is necessary to support the system.
If there is an interface, is it documented so that any third party can use these lights?
Is it possible to use a third party controller to manage these lights?
There are a number of manufacturers who build third party controllers ( Gardasoft) that can be used to control a number of manufacturers. It is an advantage if f the lights are compatible with one of these.
Is there an alternative LED solution that can be used ?
There are many suppliers. It is key to be able to use any of these to guarantee product life cycle.
Image Processing System
The IPS includes frame grabbers, PC(s) and the I/O system to control external devices. Let's look at the key components.
What make of, PC, the model and OS are used?
Often companies use special industrial solutions variants of real time operating systems. This the
means that upgrades and 3rd party operations are complicated.
Does your software support more that one version of that OS?
This will allow you to understand if the software will move along with new versions of that OS. For
example see NI’s statements on LabView. http://digital.ni.com/public.nsf/allkb/B972242574D4BB99862575A7007520CB
Can I purchase a similar PC commercially if I have an issue?
This will determine if the vendor expects you to return for all purchases. This may be the way to operate but it also will flush out any dependencies.
Is there any board used in the image processing system, including I/O that is not available commercially off the shelf?
It is important to identify if there is any proprietary component in the image processing system.
What model of frame grabber is used ?
This can be used to understand alternatives.
Name two other frame grabbers that can be used alternately.
If software is designed to avoid obsolescence then it will support more than one vendor.
Is there any specific feature on the frame grabber that is used?
Any use of a particular feature will mean that you are locked to that component.
Can this frame grabber be purchased from a local distributor and pricing?
Is it commercially available for you to purchase or are you locked into parts purchases from the
Can your software be extended to use any frame grabber and is there a cost?
If the vendor only uses one frame grabber, can they adapt their software to others and how much will that cost?
What video standards does this frame-grabber support?
Does this frame-grabber support CamLink, base, medium or full?
What bus standard does the frame-grabber support?
This will show vintage. Is it PCIE 4.0 or is it an older bus. Much more difficult to source parts for older
What I/O (input output ) card or module does the system support?
The I/O is used to control the parent machine interface.
Is the I/O interface commercially available or proprietary?
This will determine if this could be a risk in the future.
Can the system function without the I/O card or module?
If the I/O system is removed, you may not have a parent machine interface but can the system still
work. Is the software designed that is must have this module to operate. If so it is a critical part.
If the module is available commercially, and if so please provide price and local distributor?
If commercially available .the part should be capable of being purchased locally.
There are now many machine vision software packages available. Although these are not specifically
designed for the application at hand, it is important to understand that the software you are purchasing is inter operable and works with 3rd party solutions. The interface to third party products, such as historians, MES Systems and conformity to ISA 95 standards is a requirement for any industrial package.
What technology and development environment is used to develop the application?
If the software is developed using a commonly used technology, such as RSLogix for Rockwell.
LabView from NI etc. This will mean that there is a community of developers that are available to support this solution going forward.
Can the source code be es-crowed with documentation in case of calamity?
Will the supplier be willing to put the source code so that in case of major problems, third party
developers can work on fixes or extensions.
Can this software be used to run other inspection systems?
This will determine the portability of the inspection system and if there is an issue to support
commercially off the shelf components.
What is the data format that inspection results are stored?
Is it XML, or in a data base etc?
Does the software support ODBC,. OPC and other communication standards?
This will determine if the system can be easily integrated into ISA 95 line and factory solutions.
How often are new updates available?
Is this a software product that is continuously improved or is it a dead product that is being cashed out.
How much are these upgrades?
Let’s determine the total cost of ownership.
Can I deploy this software on any PC that has appropriate OS?
This will also help identify if there is any proprietary dependencies?
There are lots of key questions to ask when investing in expensive automate optical inspection systems. Use the guide above and extend to make sure that you are not left with an obsolete system years before you have recouped your return on investment.
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