Medicament injection device

A module configured to be used with or applied to an injection device, the module comprising a sensor arrangement comprising:

• a first optical sensor configured to detect a movement of a movable dosage programming component comprising a rotary encoder system having a predefined angular periodicity relative to the sensor arrangement during dosing of a medicament, wherein the first optical sensor is configured to operate in a strobe-sampling mode along a first time series of strobe pulses, and
• a second optical sensor configured to detect a rotary encoder system movement of the rotary encoder system relative to the second optical sensor, wherein the second optical sensor is configured to operate in a strobe-sampling mode along a second time series of strobe pulses, the first time series and second time series having a pulse density per time unit or a relative pulse phase varying according to a kinematical state of a dose programming component;
• and
• a processor arrangement configured to, based on the movement of the movable dosage programming component or the rotary encoder system movement, determine a medicament dosage administered by the injection device.