Apparatus and method for detecting drops in printer device

A method of determining said ink drop ejection direction of an ink ejection nozzle of an ink jet device, said device comprising a drop detector being arranged to detect drops in a first range of positions and arranged not to detect droplets in a second range of positions, said method comprising said steps of:

• ejecting one or more drops from each of a plurality of positions known relative to said edge detector, said positions being arranged such that said number of drops detected by said edge detector varies in dependence upon said magnitude of a component of said ejection direction of said nozzle;
• detecting said drops passing through said first range of positions;
• and,
• determining a component of said direction of ejection of said nozzle in dependence upon said detected drops.

In an inkjet device comprising an ink ejection nozzle arranged to traverse a print area along a scan axis and further comprising an edge detector having an edge located at an angle to said scan axis being arranged to detect ink drops at a first side of said edge but not at a second side of said edge, a method of determining an error in the component direction of ink ejection perpendicular to said scan axis, comprising said steps of:

• ejecting one or more drops from each of a plurality of positions known relative to said edge, such that at least one drop passes on either side of said edge;
• determining said proportion of drops passing to said first side of said edge;
• comparing said determined proportion with said proportion expected for a nozzle with no directional error;
• and,
• determining the magnitude of said error in dependence upon said compared value.

A method of determining said direction of ejection of an ink drop ejected from an ink ejection nozzle of an inkjet device, said nozzle being arranged to traverse a print area along a scan axis, said device comprising first and second edge detectors having respective edges arranged at differing angles to said scan axis and each arranged to detect drops in respective first ranges of positions and arranged not to detect drops in respective second range of positions, said method comprising the steps of:

• ejecting one or more drops from each of a plurality of positions known relative to said first edge detector, said positions being arranged such that said number of drops detected by said edge detector varies in dependence upon said magnitude of a first component of said ejection direction of said nozzle;
• detecting said drops passing through said first range of positions;
• and,
• determining a component of said direction of ejection of said nozzle in dependence upon said detected drops;
• and,
• repeating said steps of ejecting, detecting and determining in respect of said second edge detector to determine a second component of said direction of ejection of said nozzle.