Cameras are applied in close to all aspects of our lives; buildings are filled with CCTV, speed, and safety cameras have become a common place in the streets, and close to all modern phones have been fitted with built-in cameras. It is obvious that cameras have become an integral part of our society today. However, more people are not aware that hundreds of thousands of cameras are used behind the scenes in manufacturing industries across the globe. These cameras, also widely known as machine vision cameras, are used mostly to inspect products ranging from shampoo bottles to spark plugs and headache tablets. The list cannot be exhausted and goes on to include other industries like food and beverages, automotive, electronics, pharmaceutical, and print and packaging.
What is an Industrial Camera?
An industrial camera is a camera that has been manufactured to meet high standards of reputable performance. They are also robust enough to withstand the harsh demands of industrial environs. Industrial cameras are created in conformity to predetermined standards such as GigE Vision, Firewire, CameraLink, Coaxpress, and USB. These standards are used to ensure that camera upgrades are easily installed and also facilitate integration.
How do Industrial Cameras Work
Industrial cameras use sensors, software algorithms, and processing hardware to automate mundane or complex quality assurance procedures and guide handling of tools during product assembly. Applications of machine vision cameras include: identification, positioning, measurement, verification, and flaw detection.
Industrial cameras perform 100% online inspection to reduce production expenses, increase yields, and improve the quality of products. Consistent product quality in turn improves client satisfaction and market share in the long run.
An industrial camera consists of important components from the sensor – the camera that captures the picture – to the processing engine that concludes the result. For an industrial camera to work efficiently and effectively, it is paramount that an operator understands how its components work together.
The following text will offer an introduction to staging, optics, lighting, and cameras; these are important components of an effective industrial camera. More information on the above topics is available from the IPD, distributors, and manufacturers, and from lenses and lighting vendors.
The human eye is capable of seeing well in numerous lighting conditions. An industrial camera, on the other hand, is not capable of that. With this in mind, the controller has to light the area being inspected to ensure that the industrial camera can work effectively.
Moreover, the lighting has to be regulated and maintained at a constant so that severe changes in lighting do not interfere with the workings of the camera. The industrial camera might communicate changes in parts inspected due to variations in lighting.
Operators will prefer to use lighting that diminishes sections of the area that are not important and magnifies important elements of the area that they wish to inspect.
Proper lighting ensures that inspection is more accurate and fast. Improper lighting has proven to be a big cause of failure in industrial camera systems. In a nutshell, the normal ambient lighting will not work as it is poor lighting. For instance, the overhead lumps in an industry may burn out, dim, or get blocked: these changes can be communicated as element abnormalities by the industrial camera.
Staging, also known as fixturing, grasps the element to be inspected in front of the camera. Staging is required for a number of reasons:
- To ascertain that the element you want to inspect faces the camera. In many cases, the element is rotated to inspect a number of areas
- To hold the element still during the period that the camera is will be taking a picture. This is because, if the element is not still while a picture is being taken, the image may blur. Generally, staging freezes the motion of the part by using an electronic shutter. These shutter is a standard on ipd recommended industrial cameras
- To increase the process speed by putting the element in a location called the Vision Appliance. Industrial cameras always attempt to find particular parts in the image, and this might take time. If the operator can arrange a system where the element is always in the same location, then the industrial camera can find it quickly
Optics and Lenses
The lens is used to gather light and reflect/transmit it from the part that is being inspected and form an image on the camera sensor. Proper lenses enable users to focus on the field of view and place the camera at a good working distance from the area.
To decide on the best lens, you have to know the working distance and the field of view. The field of view is the entire area you would wish to capture.
For example, assuming that the part being inspected is 4 inches wide and 2 inches high, you will have to use a field of view that is greater than 4. Additionally, while deciding on the field of view, you ought to put into consideration the aspect ratio of the camera – the height to width view ratio. In the above example, a 4 by 2 inches area size would fit well in a 4:3 aspect ratio.
The camera is fitted with sensors that convert light emitted from the lens into electric signals. These signals are then digitized into values known as pixels which are later processed to perform a quality inspection.
The precision – resolution – of the image depends mostly on the field of view, the working distance, and the number of the pixels fitted in the camera’s sensor. Most standard VGA cameras come in 640 * 480 pixels (width * height). Each pixel is approximately 7.4 microns square. Given these values, camera resolution can be determined for the real world units.
Sensors used by industrial cameras are specialized. They are, therefore, more expensive than normal sensors. First and foremost, it is best to have square physical pixels. This is because, with square pixels, measurement calculations are more precise and easy. Secondly, the industrial camera is triggered to take a picture based on the part–in-place signal. Third, the cameras are fitted with fast electronic shutters that can freeze the movement of most elements.