Each type of inhomogeneity shows a specific transparency image. Black specks, for example, have different transparency values than gels or holes. Based on these different transparency images, typical gray value levels are defined for each type of inhomogeneity. The camera system detects the difference between the gray value of the undisturbed film background and that of inhomogeneities. The detection area and the edges of the film are automatically recognized by the system, and the light intensity is automatically controlled according to natural lighting conditions for optimal gray value analysis.

The user-friendly evaluation software determines the defect type based on its gray value, measures length and width, calculates the area and a corresponding circle diameter, and assigns the defect to the appropriate size class. The images of the detected defects are automatically color-coded according to the defect type. The effect of parameter variations (e.g. temperature) on film quality can be directly observed.

All these data are stored in a database together with the time of occurrence of the inhomogeneity and are thus available for further evaluation or transfer to Windows Office applications.

Camera:
CCD line scan camera

Resolution:
4096 pixels

Cell size:
3.75 μm x 3.75 μm

Processing area:
4096 (H) x 16384 (L)

Minimum sampling time:
10.2 μs (97.7 kHz)

Inspection width:
80 mm

Frame rate:
400 MHz 32 x

Periphery:
Controller (to be installed in the control cabinet of the downstream equipment)