Today’s display modules offer high resolution, vast color representation and refresh rates that present motion better than ever before. We find these types of displays in our tablets, mobile phones, and other personal devices both large and small. As the capabilities of display modules increase, the complexity of defects increases as well. Cameras used to detect these defects must not only have a high frame rate and resolution to surpass the competition, but also incorporate specific functionality tailored to the application. With Adimec’s focus on display inspection technology, we are able to add functionality to cameras which perform this specific type of inspection. One of these internal features is the multi-exposure function.
How to overcome “banding”?
If you have ever watched a video stream of an electronic display, you may have noticed stripes moving down the screen. When the camera exposure time is less than the display refresh period, these stripes or “bands” are produced. This condition, known as banding, negatively affects an inspection because it makes the resulting image nonuniform. In order to overcome this problem, Adimec has developed a feature found only on the D-65 camera. This feature, known as multi-exposure, takes multiple exposures of short integration times and combines them to create a band-free image.
The example shown here is an Iphone undergoing an inspection using an Adimec camera. In the first image, the exposure time is equal to the refresh rate period of 8.33ms and no bands are visible. In the second image, the exposure time is 3ms or 3/8 the period of refresh rate. 4 bands become visible as a result. In the third image, multi-exposure is active with 200 exposures being taken of 15us each over the period. The 200 exposures are averaged together resulting in an image with no visible bands.
Multi-exposure is just one of many features Adimec offers in our line of high-performace display inspection cameras. Adimec continues to be a top performer in the market by meeting the stringent requirements of our customers’ applications.
For more information on Adimec cameras, contact your local business office.