Solar Sensor with Sharp Focus
Precise and cost-effective bevel break recognition with
solar wafers / cells using the vision solar sensor by SensoPart.
SensoPart GmbH has expanded its program of vision sensors by
adding an industry-specific solution for photovoltaics: The new vision solar
sensor FA 46 is the only sensor in its price category available on the market
that measures each individual cell and is consequently able to identify the
smallest bevel inconsistencies. Thereby, it offers ideal conditions for its use
in handling areas of wafer and cell manufacturing.
Silicon wafers are
brittle and break easily - making it all the more important to prematurely
recognize bevel breaks and blemishes during the manufacturing process, in order
to avoid unnecessary costs due to machine stoppage during the subsequent
processes. Currently break controls take place by use of classic, PC-based
image processing systems. However, on the one hand the acquisition and
installation of these are costly, and on the other they are simple
contour-comparing vision sensors that do not always measure up to the demands
of precision. The vision solar sensor FA 46 by SensoPart closes this gap: As a standardised
industry solution based on the compact vision camera, it offers precise
measurement technology at a low sensor price. Consequently, considerable cost
advantages for quality assurance of solar cells become possible.
The acquisition of
the vision solar sensor FA 46 is not only cost-effective, but in comparison
with a PC-based image processing solution its installation is also
substantially easier. All relevant functions for the wafer and cell inspection,
ranging from the recognition of wafer geometry over the localization of defects
and to the adjustment of processing speed and measurement accuracy, have
already been previously configured. No knowledge of image processing is
required for configeration. The user essentially only has to input the relevant
inspection criteria, such as the tolerance for wafer size, position and
rotation as well as the size and number of allowed damages to the contour of
wafers. Then its application is ready for operation.
Automatic
Recognition of the Wafer and Cell Form
The vision solar
sensor FA 46 independently recognizes different wafer or cell forms (e.g. mono
crystalline / with bevel and poly crystalline / without bevel). This makes a
learning of contours or patterns unnecessary - only during its initial
commissioning is the sensor used once for the dimensional stability inspection
using a reference pattern. During operation the FA 46 measures each wafer or
each solar cell individually, independently of rotation, and, thereby, achieves
a high precision and dependability - e.g. it also recognizes bevel defects in
case of parameter deviations of a wafer or a cell. Consequently, it
fundamentally differs from all other solar sensors within the same price
category as these only perform one contour comparison. 
Before the
evaluation each captured image undergoes a directory correction. The contour
algorithm has been optimized for different handling variants so that incidental
light and shining-through light inspections can be guaranteed to have the same
level of precision. Solar cell contours, which are shadowed by the handling
system, can be faded out in order to avoid false diagnoses. Furthermore, the FA
46 is equipped with an automatic position tracking, which allows the cell form
to be recognized independently of the cell position in the handling system. The
same is true for faded-out areas, which are also tracked depending on their
position.