B Page 4
BEA--220265-EN-04
CCD array camera OptoLine OL 80..
With the
backlighting method
the light transmitter is positioned
behind the object to be scanned, as seen from the scanned object.
In the case of non-transparent materials, only the outer edges are
detected.
The following applies for both methods:
Whether one or two cameras are used to establish the position de-
pends on the resolution and web width required (see block diagram).
What is important is that when width measuring or web guiding with
one camera, both web edges are always in the camera visual range.
When width measuring or web guiding with two cameras, one web
edge each must be in the camera visual range.
The centerpiece of the camera is a charge coupled device with 2048
pixels. The individual pixels convert the light shed into signal voltag-
es. Contrast changes in the camera measuring range such as a web
or printed line on a web cause a change in the voltage. The
camera can detect up to 30 contrast changes in its measuring range,
regardless of whether these are caused by one or several webs. See
fig. on page 5.
A maximum of 8 measuring values can be output on the basis of the
positions recorded. A measuring value is a contrast position (e.g. the
web edge position) or the center between two contrasts (e.g. the web
or line center position).
The built-in light controller makes the camera practically impervious
to soiling caused by dust and environmental factors such as steam or
ambient light fluctuations.
All data to the camera (camera settings, measured value selection)
and from the camera (measured value position, error messages,
status information) are transferred via a CAN interface. The CAN
controller is built into the camera. The in-house E+L protocol is used
on the CAN bus. Coupling to other buses or unit interfaces is es-
tablished via special interface modules that can be attached to the
CAN bus. Two keys and a 16-bit LED display are available for basic
operating functions, setting the CAN address, focusing the camera
and displaying the measured value position. Further settings are per-
formed via an E+L command station DO.. or RT.. .
*CCD = Charge-Coupled-Device
