Control the clock pulse
Switching means are provided, each of whichis operatively associated with a respective one of the bistable controllers or control means is provided, each associated with a respective one of the measuring heads M1 to Mn a clock pulse generator CL supplies pulses at a high repetition frequency in the range of several kHz like, for example, 10 kHz. A clock pulse generator acts upon the clock pulse inputs of the bistable negative scanners controllers. Connected in parallel to the measuring heads M1-Mn is a series connection or circuit of n-bistable controllers F1 to Fn, of which is operatively associated with a respective one of the measuring heads M1 to Mn a clock pulse generator CL is provided which controls the clock pulse inputs of the bistable controllers.