Delta-sigma signal density modulation for optical transducer control
First Claim
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1. An apparatus, comprising:
- a controllable current source coupled to a light-emitting diode; and
a modulator comprising a machine-readable medium containing data that, when read by a machine, causes the machine to perform operations comprising generating a delta-sigma signal density modulation waveform and coupled to the controllable current source,wherein the modulator is configured to provide a delta-sigma modulation control signal to the controllable current source, the delta-sigma modulation control signal having a selected delta-sigma signal density to control an average luminous flux of the light-emitting diode.
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Abstract
A controller for optical transducers uses delta-sigma signal density modulation to reduce electromagnetic interference.
27 Citations
14 Claims
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1. An apparatus, comprising:
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a controllable current source coupled to a light-emitting diode; and a modulator comprising a machine-readable medium containing data that, when read by a machine, causes the machine to perform operations comprising generating a delta-sigma signal density modulation waveform and coupled to the controllable current source, wherein the modulator is configured to provide a delta-sigma modulation control signal to the controllable current source, the delta-sigma modulation control signal having a selected delta-sigma signal density to control an average luminous flux of the light-emitting diode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method, comprising:
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providing a controllable current for a light emitting diode; generating the delta-sigma modulation control signal, controlling the current with a delta-sigma modulation control signal to control a luminous flux output of the light emitting diode; and modulating the controllable current with the delta-sigma modulation control signal wherein generating the delta-sigma signal density control signal comprises; providing an n-bit modulation value A and an n-bit accumulator value B, replacing the n-bit accumulator value B with a value modulo [(A+B)/2n], and providing an output signal having a value equal to integer [(A+B)/2n]. - View Dependent Claims (12, 13, 14)
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Specification