Light-band fork sensors

Due to the natural oscillation of the thread on high spooling speeds a so-called thread-balloon comes about which as a rule is wider than the defect itself. In a round beam of a usual optosensor any lateral movement of an object is transformed into an oscillating signal due to the unavoidable Gaussian distribution of the light intensity. The impact of a geometrical defect is therefore extremely difficult to be filtered out of its course.

The light band fork sensor GLS03BS generates a light band sveral millimeters in width with a very uniform intensity distribution. A standing thread that is moved perpendicularly to the machine direction in this causes only extremely slight fluctuations of teh analogue output signal. This way the effect of a lateral oscillation movement is compensated and the observed signal variations are directly associated with the profile of the monitored object.

In combination with a dynamic amplifier out of the MICROmote® family from STM the signal peaks which are produced e.g. by quickly passing knots can be reliably filtered out with it, even in the case of a small amplitude. Due to the purely dynamic signal evaluation, slow changes, such as those that arise through the accumulation of dust from thread abrasion, cannot negatively influence the sensitivity of the sensor. It readjusts itself practically automatically and at short response times (which can be set via the so-called integration time on the amplifier).

The enclosure is made of robust aluminium and carries glass optics. The dimensions and fixing means can be adapted to customer's requirements easily.