Detection system and method for detecting movements of a movable object

Method for detecting movements of a movable object of a detection system, said method comprising the steps of:

• emitting light to a reflecting unit,
• reflecting said emitted light by said reflecting unit being arranged in functional connection with said movable object,
• detecting said reflected light by a plurality of detectors and outputting detection signals for determining a movement of said movable object by said plurality of detectors,
• detecting a tilt movement of said movable object in a first direction by a first subset of detectors of said plurality of detectors, and detecting a tilt movement of said movable object in a second direction by a second subset of detectors of said plurality of detectors, the detection of the tilt movement of said movable object being performed based on a difference in the irradiance of the reflected light on the detectors within each subset of detectors,
• said movement of said movable object including a linear movement in a third direction perpendicular to said first and said second directions, and said linear movement of said movable object in said third direction being detected based on a sum of all of the detection signals,
• and compensating for an unintentional tilt movement of said movable object in the first direction and/or in the second direction when a linear movement in the third direction is detected, wherein compensating for the unintentional tilt movement of said movable object in the first direction and/or in the second direction when the linear movement in the third direction is detected comprises:
• determining a norm of a differential signal vector, said differential signal vector being formed by the detected tilt movement of said movable object in the first direction and the detected tilt movement of said movable object in the second direction;
• calculating a derivative of said norm with respect to time;
• comparing said derivative with a predetermined threshold;
• and
• if said derivative exceeds the predetermined threshold, forcing said norm to zero such that a cursor position on a display is frozen, and if said derivative is not more than the predetermined threshold, leaving said norm unchanged,
• wherein said method comprises determining the cursor position on said display in dependence of the detected tilt movement of said movable object in the first direction and the detected tilt movement of said movable object in the second direction,
• wherein coordinates of the cursor position are stored only when the coordinates of the cursor position of an iteration are identical to coordinates of the cursor position of a previous iteration,
• and wherein the unintentional tilt movement of said movable object is compensated by restoring the cursor position to the stored values when a linear movement in the third direction is detected.