Line Rate Modes

This mode is applicable exclusively for free-run permanent exposure – LxxxxSP – class of line scan cameras when LineCaptureMode = ALL. The grabber does not perform any sampling in the downweb direction; the Downweb Line Rate is equal to the camera line rate. The camera line rate is entirely under control of the camera. Notice that most of the line scan cameras provide an internal line rate adjustment.

When the speed of motion is varying, the Downweb Line Rate should be slaved to this motion. To achieve this, a motion encoder is a good solution.
The motion encoder delivers an electrical pulse each time the moving web advances by a determined amount of length. The continuous motion results in a train of pulses the frequency of which is proportional to the web speed.
There exists another way to take knowledge of the web speed. In some applications, the motion is caused by a stepping motor controlled by pulses. The controlling train of pulses is also a measure of relative motion.
In both cases, the pulses are called line trigger pulses, and their repetition rate is the Line Trigger Rate. The line trigger pulses are applied to the frame grabber to determine the Downweb Line Rate .
Each line trigger pulse may result into the generation of one line in the acquired image. This means that the Downweb Line Rate is equal to the Trigger Rate.

Alternatively to the "PULSE" mode, for more flexibility, the Line Trigger Rate may be scaled up or down to match the required Downweb Line Rate. The proportion between the two rates is freely programmable to any value lower or greater than unity, with high accuracy. This makes possible to accommodate a variety of mechanical setups, and still maintain a full control over the downweb resolution. The hardware device responsible for this rate conversion is called the rate converter. This device is a unique characteristic of Euresys line-scan frame grabbers.

Other circumstances necessitate the Downweb Line Rate to be hardware-generated by a programmable timer, called the "periodic generator".

Applies to:

This mode is applicable exclusively for line rate controlled permanent exposure – LxxxxRP – class of line scan cameras when LineCaptureMode = ALL. The grabber does not perform any sampling in the downweb direction; the Downweb Line Rate is equal to the camera line rate. The camera line rate is entirely under control of the grabber through the exposure time settings.