Optical communication system, optical reader, and method of reading information

An optical reader communicating with an optical ID tag, in which identification information is stored, using light as a communication medium, the optical reader comprising:

• random number generating means for generating a random number;
• emitting means for emitting light having an oscillation frequency specific to the generated random number;
• photoelectric conversion means for performing photoelectric conversion to reflected light which is reflected from the optical ID tag in the emitting direction of the light emitted from the emitting means into the optical ID tag and which is modulated on the basis of the identification information;
• extracting means for extracting a signal component having the oscillation frequency from the signal resulting from the photoelectric conversion;
• and
• demodulating means for demodulating the signal component.

A method of reading identification information stored in an optical ID tag using light as a communication medium, the method comprising the steps of:

• generating a random number in random number generating means;
• emitting light having an oscillation frequency specific to the generated random number in emitting means;
• extracting, in extracting means, a signal component having the oscillation frequency from a signal resulting from photoelectric conversion to reflected light which is reflected from the optical ID tag in the emitting direction of the light emitted from the emitting means into the optical ID tag and which is modulated on the basis of the identification information;
• and
• demodulating the signal component in demodulating means.

An optical communication system comprising:

• at least one optical ID tag;
• and
• at least one optical reader,
• wherein identification information is communicated between the optical ID tag and the optical reader using light as a communication medium,
• wherein the optical ID tag includes
• a storing unit in which the identification information is stored;
• a reflecting unit that reflects incident light in the incident direction;
• and
• a modulating unit that modulates reflected light on the basis of the identification information stored in the storing unit, and
• wherein the optical reader includes
• a random number generating unit that generates a random number;
• an emitting unit that emits light having an oscillation frequency specific to the generated random number;
• a photoelectric conversion unit that performs photoelectric conversion to the reflected light incident in the emitting direction;
• an extracting unit that extracts a signal component having the oscillation frequency from the signal resulting from the photoelectric conversion;
• and
• a demodulating unit that demodulates the signal component.

An optical reader communicating with an optical ID tag, in which identification information is stored, using light as a communication medium, the optical reader comprising:

• a random number generating unit that generates a random number;
• an emitting unit that emits light having an oscillation frequency specific to the generated random number;
• a photoelectric conversion unit that performs photoelectric conversion to reflected light which is reflected from the optical ID tag in the emitting direction of the light emitted from the emitting unit into the optical ID tag and which is modulated on the basis of the identification information;
• an extracting unit that extracts a signal component having the oscillation frequency from the signal resulting from the photoelectric conversion;
• and
• a demodulating unit that demodulates the signal component.