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US 9,071,744 B1Granted
Mobile device flash calibration
AssigneeAmazon Technologies, Inc.
InventorsOmair Abdul Rahman, Ted John Cooper
Life of this patent
Estimating the term…
Abstract
Techniques for calibrating spatial uniformity of light emitted by a light source include receiving light from a unit under test with an array of photo detectors. Sampling circuitry receives an output signal generated by each of the photo detectors in response to the received light, and samples each of the output signals to generate a sampled output signal for each of the photo detectors. One or more processors determine a spatial uniformity measure of one or both of luminous intensity and chromaticity for the received light using the sampled output signals.
Claims20
A method, comprising:
- exposing each photo detector in an array of photo detectors to light from a calibration light source (CLS) having one or more of a known luminous intensity, a known geometric location with respect to the array of photo detectors, and a known correlated color temperature;
- measuring, for each photo detector, at a location proximate to the photo detector, a characteristic of light received at the location, the characteristic including one or both of luminous intensity and chromaticity;
- sampling an output signal generated by each of the photo detectors to generate a sampled calibration signal for each of the photo detectors;
- determining, for each photo detector, a corresponding calibration coefficient based on a comparison of the measured characteristic with an average indicated light characteristic determined from the corresponding sampled calibration signal, wherein each calibration coefficient is further based on the sampled calibration signal of the corresponding photo detector and the sampled calibration signals of one or more neighboring photo detectors near the corresponding photo detector;
- pulsing, through duration of a duty cycle, a light-emitting diode (LED) to expose the array of photo detectors to light output by the LED;
- sampling a respective analog output signal generated by each of the photo detectors in response to the light output by the LED, wherein sampling the respective analog output signal includes performing analog to digital conversion on each respective analog output signal to generate a respective sampled signal data set for each of the photo detectors;
- generating a corrected sampled signal data set for each of the photo detectors by using the calibration coefficients for each of the photo detectors to correct the sampled signal data set for errors, the errors relating to one or more of angular misalignment of the photo detectors, tolerance uncertainties in the performance of a photo transistor circuit, and errors induced in sampling the respective analog output signal, or in color filtering of the photo detector;
- and
- determining a spatial uniformity measure for the light output by the LED using the corrected sampled signal data set.
6 more elements
An apparatus, comprising:
- an array of photo detectors configured to receive light from a light source;
- circuitry configured to receive an output signal generated by each of the photo detectors in response to the received light, and to sample each of the output signals to generate a sampled output signal for each of the photo detectors;
- and
- one or more processors configured to determine a spatial uniformity measure of one or both of luminous intensity and chromaticity for the received light using the sampled output signals and calibration coefficients associated with each corresponding photo detector, each of the calibration coefficients based on a sampled calibration signal of the corresponding photo detector and sampled calibration signals of its neighboring photo detectors near the corresponding photo detector.
1 more element
A method comprising:
- pulsing a light source to expose an array of photo detectors to light output by the light source;
- sampling a respective output signal generated by each of the photo detectors in response to the light output by the light source to generate a sampled signal for each of the photo detectors;
- and
- determining a spatial uniformity measure of one or both of luminous intensity and chromaticity for the light output by the light source using the sampled output signals and calibration coefficients associated with each corresponding photo detector, each calibration coefficient based on a sampled calibration signal of the corresponding photo detector and sampled calibration signals of its neighboring photo detectors near the corresponding photo detector.
1 more element
Dependencies are inferred from the claim text.