An encoder is provided that is capable of suppressing accuracy deterioration even if a scale is disposed in a tilted manner with respect to a receiving unit by being rotated around an axis (i.e., a rotation axis) orthogonal to a receiving surface. The encoder 1 includes scale 2 and detection head 3. The detection head 3 includes light source (transmitting unit) 4 and light-receiving unit (receiving unit) 5. The light-receiving unit includes light-receiving surface (receiving surface) 50 and converts light received at the light-receiving surface 50 into differential detection signals with two phases and outputs the same. The light-receiving surface 50 includes element array group 7 including four element arrays 71-74 provided in a parallel manner along an orthogonal direction, with each element array 71-74 including a plurality of light-receiving elements (receiving elements) 500. The plurality of element arrays 71-74 in the element array group 7 are disposed at positions where the sum of: (i) a distance in the orthogonal direction from a reference position to a positive phase signal element array 71, 72; and (ii) a distance in the orthogonal direction from the reference position to the negative phase signal element array 73, 74, is the same for all the phases of the at least two phases.

An encoder includes scale and detection head. The detection head includes light source (transmitting unit) and light-receiving unit (receiving unit). The light-receiving unit includes light-receiving surface (receiving surface) and converts light received at the light-receiving surface 50 into differential detection signals with two phases and outputs the same. The light-receiving surface includes element array group including four element arrays provided in a parallel manner along an orthogonal direction, with each element array including a plurality of light-receiving elements (receiving elements). The plurality of element arrays in the element array group are disposed at positions where the sum of: (i) a distance in the orthogonal direction from a reference position to a positive phase signal element array; and (ii) a distance in the orthogonal direction from the reference position to the negative phase signal element array, is the same for all the phases of the at least two phases.

The invention relates to a method for measuring the volumetric flow (Q) of a fluid in a preferred direction by means of a volume measurement device having an electronic circuit and an incremental encoder, a sensor for detecting a rotational change of angle, preferably designed as two giant magnetoresistance (GMR) sensors in a double measuring bridge, wherein a first sinusoidal signal of the incremental encoder, namely a raw sine signal (S1), and a second sinusoidal signal of the incremental encoder with identical angular frequency which is phase-shifted by 90 relative to the first signal (S1), namely a raw cosine signal (S1), are generated, wherein said signals (S1) are preferably initially conditioned (S1+), interpolated/digitized (S2), and said digital signals (S2) are processed and evaluated in an evaluation unit, preferably in a process computer unit having a quadrature encoder counter. The invention further relates to a method for measuring a volumetric flow by means of a quadrature signal, comprising a first signal from a first sensor and a second signal from a second sensor having identical angular frequency which are phase-shifted by 90 relative to one another, wherein the quadrature signal serves to determine the flow (Q) of a fluid in a preferred direction by a volume measurement device having an electronic circuit. The invention further relates to a volume measurement device for carrying out a measurement method and to a programmable process computer unit having at least one quadrature encoder interface/quadrature encoder encounter for use in a volume measurement device for measuring a volumetric flow.