Device for and method for detecting a relative movement between two machine parts which are movable relative to one another

A method for detecting a relative movement of two machine parts which are movable relative to one another, comprising the steps of providing a plurality of marking rulers on one of the machine parts so that the marking rulers are arranged one after the other in a direction of movement of the machine parts;

• providing the marking rulers with increment markings for detecting a distance of a relative movement of the both machine parts;
• providing two sensors for detecting the marking rulers which sensors are arranged on the other of the machine parts and spaced from one another in the direction of relative movement at a predetermined distance of one another to sense the increment markings and to produce corresponding sensing signal;
• selecting distances between two successive marking rulers smaller than the predetermined distance between the sensors;
• using an evaluating unit for determining an absolute position of the corresponding sensor between two successive increment markings based on a phase position of the sensing signal of the sensors;
• detecting by a preceding one of the sensors as considered in the direction of relative movement a transition from one of the marking rulers to another marking ruler, detecting a phase deviation between a sensing signal of the subsequent one of the sensors located in a region of one of the marking rulers and the sensing signal of the preceding one of the sensors located in the region of the other marking ruler;
• and taking into consideration a phase correction determined on the basis of the phase deviation when the subsequent sensor is located in the region of the other marking ruler, during the detecting of the relative movement of the both machine parts.