Modulation system, modulation method, and modulator

A method for modulating an input signal in a system, the system including:

• a first modulator configured to (i) generate a control signal, (ii) modulate a first voltage value of the first modulator to be more than or equal to a predetermined value or less than the predetermined value according to the control signal, to control luminance of a first light source, and (iii) output the control signal;
• and
• a second modulator configured to (i) acquire the control signal output from the first modulator and (ii) modulate a second voltage value of the second modulator to be more than or equal to the predetermined value or less than the predetermined value according to the control signal, to control luminance of a second light source,
• wherein the first modulator generates, as an extinguishing light signal, the control signal for extinguishing the first light source by a predetermined extinguishing period to be recognized by a human, and
• after a lapse of the extinguishing light period, the first modulator generates, as a light information signal, the control signal for transmitting a visible light signal by change in luminance of the first light source.

An apparatus modulating an input signal for luminance of a light source, the apparatus comprising:

• a switch that switches a voltage value;
• a processor;
• and
• a memory storing thereon a computer program which, when executed by the processor, causes the processor to perform operations including:
• generating a control signal and controlling the switch according to the control signal, to modulate the voltage value to be more than or equal to a predetermined value or less than the predetermined value, luminance of the light source being controlled according to the modulated voltage value;
• generating, as an extinguishing signal, the control signal for extinguishing the light source by a predetermined extinguishing period to be recognized by a human;
• and
• after a lapse of the extinguishing period, generating, as a light information signal, the control signal for transmitting a visible light signal by change in luminance of the light source.