Apparatus and Method for Detecting a Reversion of Direction of a Relative Movement

A reversion-of-movement sensor, comprising:

• a first sensor signal input;
• a second sensor signal input;
• a comparator comprising a first input and a second input;
• a differentiator coupled between the first input of the comparator and the first sensor signal input or the second sensor signal input, the second input of the comparator being coupled to the other one of the first sensor signal input or the second sensor signal input;
• and
• a processor coupled to an output of the comparator and comprising an output for a reversion-of-direction signal.

A reversion-of-movement sensor comprising:

• a periodic scale defining a periodic field;
• a first sensor signal input and a second sensor signal input;
• a field-sensor arrangement responding to the periodic field with a first sensor signal at the first sensor signal input and a second sensor signal at the second sensor signal input such that, in a first direction of movement of a relative movement between the periodic scale and the field sensor arrangement, the first sensor signal is advanced from the second sensor signal and, in a second direction of movement of the relative movement between the periodic scale and the field sensor arrangement, the second sensor signal is advanced from the first sensor signal;
• a comparator comprising a first input and a second input;
• a comparator coupled between the first input of the comparator on the one hand and one of the first sensor signal input and the second sensor signal input on the other hand, the second input of the comparator being coupled to the other one of the first sensor signal input and the second sensor signal input;
• and
• a processor coupled to an output of the comparator and comprising an output for a reversion-of-direction signal.

A method of detecting a reversion of direction of a relative movement between a periodic scale for defining a periodic field and a field sensor, the method comprising:

• outputting first and second sensor signals upon the periodic field defined by the periodic scale such that, in a first direction of movement of the relative movement, the first sensor signal is advanced from the second sensor signal and, in a second direction of movement of the relative movement, the second sensor signal is advanced from the first sensor signal;
• determining a difference between one of the first sensor signal and the second sensor signal on the one hand and a signal corresponding to a temporal change of the other one of the first sensor signal and the second sensor signal on the other hand;
• and
• detecting a reversion of direction of the relative movement dependent on a certain difference.