Method and apparatus for illumination and communication
First Claim
1. An apparatus comprising:
- a) a plurality of light-emitting elements configured to emit a variable intensity visible light for both general illumination and a communication of data;
b) a control means for generating a continuous carrier signal for controlling a luminous flux output of the plurality of light-emitting elements, the carrier signal comprising a plurality of phase-shifted dimming signals for the plurality of light-emitting elements, respectively, each of the plurality of dimming signals having a duty cycle for operation of an associated light-emitting element included in the plurality of light emitting elements;
c) a modulation means for generating a data signal including encoded data for superposition on the carrier signal thereby forming a control signal for further controlling the luminous flux output of the plurality of light emitting elements in a manner that does not result in a visible flicker, the control signal formed by employing a peak amplitude modulation of substantially less than 100%, wherein the control signal is formed with the encoded data unconstrained by a minimum duty cycle of at least one of the plurality of dimming signals;
d) a sensing means for detecting at least a portion of the luminous flux output; and
e) means for extracting the data signal from the detected luminous flux output.
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Accused Products
Abstract
The present invention provides a method and apparatus of using light-emitting elements for illumination as well as communication of data, wherein potential flicker due to sub-fusion frequency data correlations can be reduced compared to prior art techniques, while reducing redundancy in the data transmission. The intensity of the illumination from the light-emitting elements is controlled by a dimming signal such as a pulse width modulation (PWM) signal or a pulse code modulation (PCM) signal, for example. An amplitude-modulated data signal is then superimposed on the dimming signal for communication of data. The dimming signal thus acts as a carrier signal for the data signal. A sensing means is then used to receive the data signal by detecting all or part of the illumination from the light-emitting elements. The data signal can subsequently be extracted from the detected illumination.
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Citations
14 Claims
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1. An apparatus comprising:
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a) a plurality of light-emitting elements configured to emit a variable intensity visible light for both general illumination and a communication of data; b) a control means for generating a continuous carrier signal for controlling a luminous flux output of the plurality of light-emitting elements, the carrier signal comprising a plurality of phase-shifted dimming signals for the plurality of light-emitting elements, respectively, each of the plurality of dimming signals having a duty cycle for operation of an associated light-emitting element included in the plurality of light emitting elements; c) a modulation means for generating a data signal including encoded data for superposition on the carrier signal thereby forming a control signal for further controlling the luminous flux output of the plurality of light emitting elements in a manner that does not result in a visible flicker, the control signal formed by employing a peak amplitude modulation of substantially less than 100%, wherein the control signal is formed with the encoded data unconstrained by a minimum duty cycle of at least one of the plurality of dimming signals; d) a sensing means for detecting at least a portion of the luminous flux output; and e) means for extracting the data signal from the detected luminous flux output. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for providing visible light for both general illumination and a communication of data, the method comprising the steps of:
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a) generating a continuous carrier signal for controlling a luminous flux output of a plurality of light-emitting elements, the carrier signal comprising a plurality of phase-shifted dimming signals for the plurality of light emitting elements, respectively, each of the plurality of dimming signals having a duty cycle for operation of an associated light-emitting element included in the plurality of light emitting elements; b) generating a data signal including encoded data; c) combining the carrier signal and the data signal thereby forming a control signal by employing a peak amplitude modulation of substantially less than 100%, the control signal for further controlling the luminous flux output of the plurality of light emitting elements in a manner that does not result in a visible flicker and forming the control signal with the encoded data unconstrained by a minimum duty cycle of at least one of the plurality of dimming signals; d) sensing at least a portion of the luminous flux output; and e) extracting the data signal from the sensed luminous flux output. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification