|Scratch detected on laptop housing using contrast measurement.|
Customers of today’s consumer electronics devices expect a flawless product out of the box. Scratched, dented, and otherwise imperfect products result in costly returns and may damage your brand’s reputation and future business. Quality control activities to prevent and detect surface defects rely largely on human inspectors. Humans can apply their acute visual perception and immediate judgment during production to ensure defective products are not shipped to consumers. However, the faster the production rate, more complex the product, or more obscure the defect, the more difficult it is for humans to keep up with throughput demands while adhering to the need for absolute quality.
Unmatched Camera Resolution and Dynamic Range
|Comparison of Radiant versus Other Imaging Solutions|
|Radiant ProMetric® Y29 (29-megapixel CCD Imager)|
|71-megapixel CMOS Imager|
A Radiant CCD imaging solution offers superior dynamic range for surface inspection, even when compared to higher-resolution CMOS systems. In the example above, two cameras are used to image a scratched aluminum surface (dark images on left), and contrast differences are analyzed to identify surface scratches (graphs on right). The first image was captured using a Radiant ProMetric Y29 (29-megapixel) imaging system. The corresponding graph shows four large peaks where four scratches are identified. The bottom image was captured using a third-party 71-megapixel CMOS vision system. Even to the human eye, this image exhibits fewer contrast differences. In the corresponding graph, only three large peaks are registered, indicating that the CMOS sensor does not have sufficient dynamic range to identify the first scratch (indicated by the left-most of the four peaks in the Radiant analysis graph).
Unknown Defects in Unknown Locations
Dent detected on tablet back.
Radiant offers complete CCD-based camera systems that use advanced imaging technology and sophisticated algorithms to locate and characterize randomly-occurring cosmetic defects on device surfaces, including unknown defects in unknown or unpredictable locations on a part. By taking a wide area image of a device, our systems can perform uniformity checks to detect hairline scratches, subtle dents, or even fingerprints on device surfaces. The systems can classify the severity of each defect against acceptable tolerances and apply pass/fail values, just as a human would use their judgment to determine a reasonable margin of error.
Unlike human inspectors, however, Radiant solutions can apply numeric values to each defect and quantify these by size, shape, location, frequency, and rate of occurrence, building trend analysis data that allow you to fine-tune processes, improve product quality, and increase production efficiency. Built on the Radiant TrueTest Software platform, these systems can simultaneously perform other inspections, including part orientation, assembly verification, fit and finish analysis, and label legibility, eliminating the need for a separate machine vision system on the line.
Photometry-Based Evaluation of “Just Noticeable Differences”