Today we will introduce each case how the area scan camera and line scan camera introduced last time are used in the field of visual inspection. We would like to pick up some concrete work examples. In this way, we will organize the points of camera selection.
| Comparison items | Area camera | Line camera |
|---|---|---|
| price | Cheap | Expensive |
| Size of inspection target | Suitable for small objects | Can image large objects |
| illumination | Difficult to apply uniform lighting (Because the entire imaging surface is illuminated, uneven lighting is likely to occur depending on the location) |
Easy to apply uniform illumination ( uniform illumination can be applied to the imaging line) |
| accuracy | A rich lineup of resolutions and many choices | The resolution lineup is small, but there are high-definition products |
| Ease of handling | Easy to set up and install | It is difficult to install equipment and adjust speed because the inspection target is moved. |
As you can see from the table, area cameras have the advantages of being inexpensive and easy to handle, but they also have the disadvantages of being limited in the size of the inspection target and being difficult to illuminate. On the other hand, line cameras are expensive, but they have the advantages of being able to capture large inspection targets and making it easy to apply uniform lighting.
At the actual site, the requirements and budget are used to determine the characteristics of the object (hereinafter referred to as the work) that you want to shoot, but here we will focus on the requirements.
In the first place, the purpose of imaging in visual inspection is to maximize the difference from the normal state. In other words, when an abnormality occurs in the target work, it is necessary to make it clearly visible, and the imaging method changes depending on the type of work and the type of characteristic of the abnormality. Also, in the actual field, it is rare that the characteristics of anomalies are limited to one, and it is necessary to capture a combination of multiple anomalies.
So what are the requirements that area scan cameras and line scan cameras can meet?
Area scan camera is a versatile player that can handle various works
The range to be imaged is limited
Area cameras are suitable for precision equipment parts and industrial parts where the work size is small and the imaging range is limited. Also, even if the work is large, the area camera will be suitable even if the area to be imaged is limited.
Specifically, burr-like features that are uttered in the production process of manufactured parts are often found in materials that are filled and manufactured, and many of them are easy to identify where they occur, so area scan cameras are often used. Area cameras are also used to inspect the lids of PET bottles for burrs that exceed the specified amount, as shown in the photo below.
According to DZOptics, the range to be imaged is affected by the specifications of the camera and the lens, so it is necessary to consider it together. For the same reason, area scan cameras are suitable because the place where the product package label, barcode, and OCR are printed is fixed.
When the workpiece has a complicated shape and it is necessary to take images from various directions
When a person looks at something with a complicated shape, I think he sees it from multiple directions. It seems that it is because it becomes a shadow and cannot be seen from one direction. You may also want to see purely multiple aspects. With the area scan camera, you can flexibly build an imaging environment. For example, it is common to place multiple cameras around a work piece, or attach a camera to an industrial robot to take images of multiple locations.
In addition, area cameras are sold by various companies and have a large lineup, so you can get them at a relatively low price. Therefore, it is also a feature that it can be used for various imaging methods.
