Line Period for Controlled Exposure
In the controlled exposure operational mode, the maximum line frequency can be dictated by the camera performance, or by system constraints.
Two cases are to be considered:
- The exposure time is shorter than the readout duration,
- The exposure time is longer than the readout duration
Short exposure time
The maximum line frequency is dictated by the camera, exactly as it is in the case of the permanent expose situation.
The maximum line frequency is tied to the readout process duration. The following formulae can be used.
Operating the camera at the maximum rate as described here implies an exposure time even shorter than in the case of the permanent exposure situation. The sensitivity is usually so low that an intense illumination of the inspected web is needed.
Long exposure time
Shortening the exposure time drastically reduces the sensitivity of the camera. Sometimes, it is simply not possible to achieve an adequate response with a short exposure time and a reasonable illumination device.
If the needed exposure is longer than the readout duration, then the maximum line frequency is dictated by the exposure time rather than by the camera performance.
The maximum line frequency is tied to the exposure duration. The following formulae can be used.
