Display system and method of operation

A method for displaying a desired image using a plurality of display modules, each having at least one light source moveable along a respective predetermined closed path, the method comprising:

• arranging the plurality of display modules into at least two groups, each of the at least two groups comprising one or more of the plurality of display modules, and the predetermined closed path of the or each display module in each group lying in a plane associated with the group, the plane associated with each group being unique to that group;
• disposing the display modules such that each lies within a region around an intersection of a row and a column in a grid, each module being adjacent, in its row and column, only to modules in a different one of the at least two groups, the light sources of each adjacent pair of display modules moving along their predetermined closed paths in opposing senses and the predetermined closed paths of each adjacent pair overlapping;
• and
• carrying out the following steps at each of the plurality of display modules:
• moving the at least one light source along its respective predetermined closed path;
• modulating an intensity of light emitted by the at least one light source of each of the plurality of display modules as it moves along its respective predetermined closed path so as to cause a respective portion of the desired image to be visible by virtue of persistence of vision, the respective portions of the desired image visible on each of the plurality of display modules together forming the desired image;
• generating a respective synchronization signal including a synchronization feature indicating a passage of the at least one light source past a datum point on the respective predetermined closed path;
• receiving a reference signal including a periodic timing feature having a period based on a desired speed of revolution of the at least one light source along the respective predetermined closed path;
• and
• controlling a speed with which the at least one light source moves along the respective predetermined closed path such that a phase shift between the synchronization feature or a phase-shifted version of it and the timing feature or a phase-shifted version of it is maintained at a predetermined value;
• wherein the predetermined value of the phase shift between the synchronization feature or phase-shifted version of it and the timing feature or phase-shifted version of it for each of the plurality of display modules is selected such that the at least one light source does not occupy a position in which it obscures the at least one light source of another of the plurality of display modules;
• wherein the predetermined value of the phase shift comprises an initial phase shift for each display module that is adjusted by a user-input calibration amount to account for misalignment of the display module with one or more adjacent display modules.