Application of Bi-telecentric Lens and Industrial Camera in Ballpoint Pen Refill Inspection

Industrial cameras have been in development for nearly 20 years. The term and concept are familiar to everyone, but many people will feel strange when it comes to bi-telecentric lenses, but in our actual production and life, projects that require machine vision inspection are implemented. In the process, many problems have to be solved by double telecentric technology. Next, we will start with the concept of telecentric lens, and then use some practical cases we have done, such as "double telecentric lens in ballpoint pen core." Application in Inspection "to analyze the advantages and problem solving capabilities of bi-telecentric lenses.

Telecentric lens (Telecentric) is mainly designed to correct the parallax of traditional industrial lenses. It can be within a certain object distance range, so that the magnification of the obtained image will not change. The extremely low distortion and super depth of field are double telecentric lenses. For this reason, telecentric lenses have always been favored by machine vision applications that require high lens distortion. In this article, we will take the BT series bi-telecentric lens as an example to introduce the practical application of bi-telecentric lens for everyone.

Detected object

Ballpoint pen refill

Testing requirements

Ballpoint pen cores can be divided into different types such as extra fine, thin, medium, and thick according to the diameter of the tip ball. In this case, the tip ball needs to be measured in order to quickly and accurately classify the ballpoint pen core.

Project Difficulties

During the inspection, it is necessary to take a clear image so that the edges of the ballpoint of the ballpoint pen tip can be clearly seen. However, because the ballpoint of the ballpoint pen core is very small, it is difficult to obtain an ideal picture, and it is extremely difficult to compare and classify.

solution

In this test, the requirements for product accuracy are relatively high. We used a 5 million CCD industrial camera, and the lens used a micro-magnification lens and a BT series bi-telecentric lens.

The comparison of the effects presented by the two is as follows:

Imaging effect of bi-telecentric lens


The lens used in Figure (1) is a common micro-magnification lens. We can see that the image presented is because the magnification is too large, the lens resolution is not enough, and because the depth of field is too small, the edges of the tip beads appear very blurred.

Figure (2) is a photo taken with the Vision series BT series bi-telecentric lens. Not only can we clearly see the edge of the ballpoint of the ballpoint pen core, but also the connection between the pentip and the ballpoint. Such images are more conducive to customer's later image processing. Not only can it be easily measured and classified, but it can also be easily applied to pen tip defect detection and quality judgment.

Bi-telecentric lenses have been widely used in high-precision inspection and precision measurement. If you are interested in related products, you can contact iJUNCO engineers for detailed answers.