Installing and implementing a machine vision system with line scan cameras for automatic quality assurance has numerous benefits for a large variety of industries.
What is a line scan camera?
A line scan camera is a compact sensor featuring a single line of pixels. It captures images line by line. This is particularly useful when the object or action being monitored is continuous and fast moving.
The line scan camera is set to grab a certain number of lines or slices per second, in order to capture the entire surface of the object passing in front of it, as it moves.
The high-speed camera needs to be combined with the appropriate hardware and software and properly synchronized with them, in order to work impeccably and capture every single detail of the monitored objects and surfaces.
The frame rate is the number of slices which the line scan camera needs to capture in order to enable the software to stitch the lines properly and in a consecutive manner and create a full, non-blurred and non-distorted image.
The frame rate depends on the speed of the moving object. When a conveyor line is being monitored, a linear motion encoder measures the speed of the line in order to ensure that the line scan camera is capturing every single line of the passing object.
Rotary motion encoders are used for calculating the start and end point of an object when rotating objects are being monitored.
When individual objects are the subject of the quality control, trigger impulses signal the start and the end of an object is.
A frame card is used for synchronizing the lighting with the camera sensor, and specialized software processes the captured data and unifying it together to create a full image.
The appropriate lighting sources need to be carefully positioned, installed and synchronized with the camera for consistent image capturing.
The advantages of using line scan cameras for automated quality assurance
There are multiple advantages of using automated quality control, inspection and process guidance provided via machine vision systems with line scan cameras.
Here are some of the advantages for a production with a machine vision system for quality control:
- Reduction of manual inspection costs
- More detailed and precise control than human inspection
- Reduction of waste and scrapped production materials
- No need for stopping a continuous production for quality control – saves time and money
- No losses due to missed service level agreements
- Saved time and reduced losses for technical support and crisis resolution
- Automated quality assurance systems are focused 100% on one task – to monitor the quality of the production and spot problems or defects
- 24/7 reliable and continuous work without breaks
- Line scan cameras are very small so they can be positioned in very compact spaces where no other method of observation and control can be used
- You can redirect your employees for other tasks
- Can inspect the entire production rather than just samples of it
- Saves costs for re-inspections
- Helps you act in real time in case of issues with the quality
- Higher production yields and lowered costs
- Consistent product quality and satisfied customers
- Great ROI
Industries which use line scan cameras
The most common uses of line machine vision systems equipped with line scan cameras include all industries which have continuous production processes. The line scan camera is especially useful for non-stop inspection of long web lines, metal sheet, glass, textiles, paper, plywood, wood and other similar products on moving conveyor lines.
The line scan cameras are also superb tools for quick and uninterrupted sorting of various passing and free falling objects such as fruits, foodstuffs, pharmaceuticals, solar panels, solar cells, postal packages and others.
They can provide reliable quality control of production processes involving molten glass and metal.
Also, line scan cameras are impeccable for fast print scanning, as well as for monitoring rotating and rolling products on a production line.
These systems for quality and process control and monitoring are perfect for any industry or activity which involves continuous fats moving objects and actions.
Line scan cameras are also essential tools used in various races and sports games. They are used to capture the photo finish or other very detailed and precise images which are used for determining the winners in a sprint or other race.
Non-traditional implementations of line scan cameras
Line scan cameras are highly effective for all kinds of moving processes and can serve not only as quality assurance tools but as positioning, verification, identification, measurement and flaw detection tools as well.
They are also used for some non-traditional business and scientific purposes, including determining glass thickness, laser diffraction, shadow boundaries, laser triangulation and for observing quickly moving processes in the natural world.
They are very useful for scanning fruit and food lines to determine whether there is a non-conforming or a foreign object on the line and remove it.
What are some of the different types of line scan cameras available?
The typical line scan camera uses a single line of light sensitive pictures to capture consecutive lines of an object or action.
There are line scan cameras which have 2 lines of pixels and capture the same line twice, in order to provide an even more detailed and much brighter image. These are perfect for settings where there is low or inconsistent lighting.
Time Delay Integration line scan cameras have multiple lines of pixels allowing for the sensor to capture the same slice of the object multiple times. This multiple exposure feature is especially useful for capturing incidental light and creating detailed images in any kind of setting.
The newest TDI cameras feature up to 256 settings which allow them to capture images with sensitivity 256 times greater than a standard line scan camera.
There are line scan cameras which are either analog or digital. The sensors can have interlaced or CCD (progressive) scanning features. Other interfaces used in modern line scan cameras include FireWire and GigE.
One of the newest types of line scan cameras are integrated smart cameras with their own processing units, a frame grabber, a processor, and memory. This allows for the images to be processed directly and even evaluated by the camera itself. They don’t need the assistance of other hardware, so they can work individually as small vision systems by themselves.
Other types of line scan cameras can create 3D images which are very useful for various industries and tasks too.
Users can choose between monochromatic and color line scan cameras depending on their needs as well.
Final words
Line scan cameras are very specific cameras which are absolutely irreplaceable for a number of different tasks and purposes. Most commonly they are used for machine vision systems for process control, monitoring and quality assurance. They can work without stopping, or without the need of stopping the production or any other fast moving process.
The ROI of industries which implement such systems is great, given all the time, money and human resources saved for the perfect quality and other control provided by these systems equipped with line scan cameras and the appropriate hardware and software to process and analyze the captured images.
