Magnetic encoder uses versatile tape and read head

The secret behind the innovative new system lies with magnetic markers that are placed at intervals along the length of the tape. As the incremental sensor in the reader head passes over the tape (at traverse speeds of up to 4m/s), the magnetic field is converted into an electrical signal, which is sampled by a micro controller. Because the field between the markers varies sinusoidally, the micro controller is able to determine the position of the sensor in relation to each marker. The analogue information collected is then converted into an industry-standard TTL (RS422) differential quadrature signal.

Reference marks (RM) are located periodically and parallel to the main incremental track. These are detected by the index sensor in the reader head and output as the RM signal. The reference signal is synchronised to the A and B signals.

Designed with both ease-of-use and ease-of-installation in mind, Newall's IP67-rated MAG-TT encoder system can be mounted quickly and easily on any fixed surfaces using the adhesive side of the tape. The tape scale can be attached to an optional twin-track backing bar supported by stand-offs for applications where the mounting surface is uneven.

Newall, which is part of the Schneider Electric group, is making the MAG-TT available in four different models. Depending on the precision requirements of the end-user application, Newall's engineers can offer variants providing accuracy between +/-0.1mm and +/-0.01mm, and resolution between 0.05mm and 0.001mm.