Several technologies are known to exist for making panels for displaying varying alphanumeric messages, in particular for roadsigns or for advertising displays. Such panels are often implemented by assembling unit modules or subassemblies which are constituted by a portion of the main screen and an image-creating device. Optical fiber panels make it possible:
to display a plurality of pre-established symbols or messages of various colors and shapes;
to flash at an adjustable frequency and thus attract attention; and
to possess a high level of brightness in the observation direction with low electricity consumption, thereby remaining visible even under extremely unfavorable conditions.
The device may be of the electromechanical type having, for example, occultation means associated with one or more optical fibers for each point or pixel of the screen.
Whatever type of lighting is used, light sources always suffer from the drawback of presenting a large amount of dispersion in their performance. Panels comprising a plurality of light sources therefore lack uniformity in message display, since each of the subassemblies cannot reproduce the same brightness. In addition, light sources such as arc lamps, halogen lamps, or lasers, for example, deteriorate over time, and often differently within a single batch of such sources. As a result the differences in brightness between the subassemblies of a given panel can only get worse over the lifetime of the light sources.