LED inspection system with reel-to-reel option

With the further development, Schneider & Koch is clearly pursuing its own corporate strategy of aligning existing inspection systems even more closely with customer requirements. "When we talk about the testing of LED products, we've also got to think about how rolled LED ribbons can be tested.

That's why we've decided to continue developing the existing LaserVision-LED system for testing these luminants. Technically, this demands some changes inside of the machine," explains Ronald Block, managing partner at Schneider & Koch.

Position monitoring is especially challenging, because the LED ribbons are very flexible. The monitoring is done during handling, whereby contacting is also ensured. This contacting occurs in the edge area and presupposes repeat contacting. Because the user often cut LED ribbons to the desired size, the roll material often contains recurring units.

That's why repeat contacting is possible. The ribbons can be up to 600 mm wide. No roll length is defined. That way, different LED ribbons with differently placed LEDs can also be tested on a single roll. But separate ribbons on different rolls can also be simultaneously inspected.

The power supply's ability to supply the entire roll, or several rolls in parallel if needed, must be guaranteed while the rolls are being inspected. The maximum current is not needed, because a test can also succeed at low power.

It is important, because of intense heat generation in such cases, that LED rolls are not permanently energised. The heat generation can be controlled with a targeted current feed that can be switched via a matrix.

A vacuum table fixes the LED ribbons during the inspection process. The test head is mounted on an X/Y axis and travels to the individual inspection points. Complete testing of the assemblies is possible in the process. This includes AOI testing as well as testing of the LEDs regarding their light parameters.

There are two different testing approaches for LED tests. The cycle-time-optimised approach employs the camera used for testing during AOI. Testing can certainly also be conducted via an integrated spectrometer.

However, this is not fundamentally necessary, because the camera often delivers adequate results. The spectrometer can be drawn upon for more exact measurements. Because a very slow spectrometer measuring, it's unsuitable for use in mass production.

"Both testing processes are combined in our system, whereby LaserVision LED unites the advantages of both: rapid testing with the camera and exact measurement with the spectrometer", explains Block. The unique feature is the matching.

A board can be measured with the spectrometer and then brought into agreement with the camera system. Testing is done at the individual-LED level. LED lights can be tested completely as final products and also in different production levels. An additional camera is optionally available for testing ultra-bright LEDS.

The LED ribbons are rewound onto a roll at the conclusion of testing. However, subsequent cutting to a single roll ready for sale can also be done. "LaserVision LED acquires another unique feature with this additional option for testing LED ribbons.

That's why we're introducing the system for the first time at this year's Light & Building. Many manufacturers of LED strips and LED ribbons are exhibiting there, and we cordially invite them to become acquainted with the new form of quality assurance", according to Block. Schneider & Koch is exhibiting in hall 4.1, booth F11.