Smart phone screen glass inspection

High speed, smooth indexing and a high level of repeatable accuracy were the performance demands placed on linear motion expert HepcoMotion for a smart phone screen glass inspection system for a major consumer electronics brand.

A PRT2 precision track system is installed and working as part of an automated inspection cell in Vietnam on a 24/7 basis.

An oval PRT2 size 25 track system is employed and fitted with eight carriages.

There are eight stations in the system; six inspection stations as well as a station for loading and a station for unloading.

Robots unload and load the mobile phone glass screens. Zero play and precise positioning enables highly accurate inspection work to place at each station.

The system indexes the glass to a series of workstations for inspection, moving at a speed of 0.2m/s intermittent motion.

After each inspection operation, the drive indexes each carriage 200mm to the next workstation.

Cameras and high intensity lighting are used on each of the six stations to inspect the glass for scratches, blemishes and imperfections.

The cameras inspect the glass from different angles and elevations including top straight, top angles, sides, ends, as well as curved glass edges.

Approximately 360 mobile phone screens are inspected every hour.

Accuracy of the track system was fundamental to this application to ensure that the glass is positioned in the right place for the cameras to inspect.

Hepco’s PRT2 can deliver up to +/- 0.05mm accuracy; for this application, ±0.5mm is required which the PRT2 can eminently deliver.



A further element of the design is that it had to be low maintenance. Systems that can deliver continuous and smooth operation without the need to be regularly stopped for routine maintenance such as re-lubrication, are highly valued by designers. This was particularly pertinent in this application due to the 24/7 operation.

The PRT2 system is based on Hepco’s proven and precision V guide technology, rigidly guiding the carriages around the track, ensuring accurate alignment and resistance to deflection.

The system has been in place for over a year, in operation 24/7 and has proven to be very efficient. Hepco’s PRT2 is working trouble-free, providing a consistent inspection process with improved production rates.