During the production of solar wafers strings, these crystalline wafers are automatically destacked with vacuum grippers.  During this process more than one wafer can be   inadvertently removed from the stack.  If this duplication is not detected then the additional wafer will sooner or later fall down and burst in many pieces.  This debris will ruin other wafer strings increasing unnecessarily the scrap rate.

In order to increase the uptime and the output the Roland Electronic company located in Germany has developed a dual layer detector for crystalline solar wafers. 


The sensor is based on eddy current technology and features an integrated amplifier for the connection to an analog input of a PLC.

Technical Data:

Measuring principle:     Eddy current
Size:            M12 x 71 mm length
Sensor Weight:        40 grams
Connection:        Fixed cable or connector
Sensor Gap:        0...1.5 mm to wafer surface
Power Supply:        24 VDC
Wafer Types:        Multi-crystalline, Mono-crystalline
Wafer Thickness:    100 to 300 µm

The standard sensor WF12 is suitable for all types of vacuum grippers.  However, the sensor electronics can also be integrated in special enclosures as demonstrated by the example WF14 for the Schmalz Wafer Gripper of the series SWG, which was displayed on the recent Photon Exhibition in Stuttgart, Germany.  The sensor electronics has been designed in such a fashion that it can be relatively easily fitted into other enclosures.