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US 6,720,544 B2Granted
Feedback stabilized light source with rail control
AssigneeMicron Technology, Inc.
InventorsSandor L. Barna, Scott Patrick Campbell
Life of this patent
Estimating the term…
Abstract
A digitally controlled light source system. The light source produces an output which is sensed by a photoreceptor within the feedback loop of an operational amplifier. This maintains the output of the light source constant. The feedback loop can also have a digital control system, to enable digital control of the output.
Claims17
A light control circuit, comprising:
- a semiconductor based light source which illuminates based on an amount of drive thereto;
- an analog amplifier;
- a semiconductor based photoreceptor, located adjacent said semiconductor light source, to receive light from said light source;
- and
- a digitally-controlled resistance element, controlled by a plurality of bits, said digitally-controlled resistor element being coupled to said semiconductor based photoreceptor, for producing a control signal based on light received at said photoreceptor and based on values of said plurality of bits;
- wherein said analog amplifier has a first input which receives a signal voltage, and a second input which receives said control signal, said analog amplifier producing said amount of drive based on a relationship between said first input and said second input.
3 more elements
A circuit, comprising:
- a semiconductor light source;
- an analog amplifier, having an output which drives said semiconductor light source, and operating based on feedback within a feedback loop, said feedback loop feeding back a signal indicative of an amount of received light from said semiconductor light source;
- and
- a digital control element, located within a feedback loop of the analog amplifier, and producing a digitally controlled resistance within said feedback loop;
- wherein said digitally controlled resistance controls an amount of drive of said analog amplifier.
2 more elements
A method for controlling an optical system having a light source and a photosensitive element, comprising:
- generating a voltage, said voltage being based on light sensed from said light source by said photosensitive element, and said voltage being further based on a resistance controlled by a digital control word;
- applying said voltage within a feedback loop of an analog amplifier to set an amount of drive to said light source.
Dependencies are inferred from the claim text.