A magnetic field sensor including an amplifier and a magnetic field element for outputting a signal to a switch circuit according to the strength of an applied magnetic field. The slider is accommodated in the guide rail such that the slider is displaceable in a longitudinal direction of a vehicle and carries the roller blind. The diode pumped fiber laser is fiber-coupled with an optical fiber, either passive or diode pumped, to a generation laser head. Preferably, a table memory is provided for mapping a number of signaling codes to a number of corresponding items of information.