Device for controlling the variations in time of the power of a lighting installation in relation to a preset programme

In a lighting installation comprising a plurality of light sources connected to an A.C. power supply system, control means for controlling the variation with respect to time of the power of illumination of said installation, said control means comprising, associated to each light source:

• a clock circuit delivering clock signals at predetermined time intervals;
• reset means connected to said power supply system and to said clock circuit for resetting the clock circuit in response to the switching on of the power supply system;
• circuit means having stored therein in a non-volatile form a predetermined illuminating programme representing a desired step-wise variation of the illuminating power of said light source over a working period of the lighting installation;
• selection means connection to said clock circuit and programme circuit means and including counting means for counting said clock signals;
• control signal generating means connected to said programme circuit means for generating a control signal having a magnitude which varies in a step-wise manner and is representative of a value selected in said programme circuit means as a function of the number of clock signals counted by said counting means;
• means connected to said control signal generating means for varying progressively the magnitude of the control signal from one step to another;
• a switching circuit connected between a terminal of said power supply system and the light source;
• and
• a control circuit connected to said switching circuit and responsive to said control signal for controlling the closing of the switching circuit during a fraction of each alternation of the power system voltage, said fraction having a duration which is a function of the magnitude of the control signal.