David Dale Knapp

US Patent:

20210007192, Jan 7, 2021

Filed:

Mar 16, 2020

Appl. No.:

16/819497

Inventors:

- Coopersburg PA, US
Jason E. Lewis - Driftwood TX, US
David J. Knapp - Austin TX, US

Assignee:

Lutron Ketra, LLC - Coopersburg PA

International Classification:

H05B 45/10
G01J 3/46
G01J 3/50
G01J 1/02
G01J 3/02
H05B 45/22
H05B 45/24
H05B 47/10
H05B 47/105
H05B 47/24
H05B 47/21
G01J 1/32
G01J 1/42
G01R 31/44

Abstract:

An illumination device and method is provided herein for calibrating individual LEDs in the illumination device, so as to obtain a desired luminous flux and a desired chromaticity of the device over changes in drive current, temperature, and over time as the LEDs age. The calibration method may include subjecting the illumination device to a first ambient temperature, successively applying at least three different drive currents to a first LED to produce illumination at three or more different levels of brightness, obtaining a plurality of optical measurements from the illumination produced by the first LED at each of the at least three different drive currents, obtaining a plurality of electrical measurements from the photodetector and storing results of the obtaining steps within the illumination device to calibrate the first LED at the first ambient temperature. The plurality of optical measurements may generally include luminous flux and chromaticity, the plurality of electrical measurements may generally include induced photocurrents and forward voltages, and the calibration method steps may be repeated for each LED included within the illumination device and upon subjecting the illumination device to a second ambient temperature.

US Patent:

20170105260, Apr 13, 2017

Filed:

Dec 22, 2016

Appl. No.:

15/388607

Inventors:

- Austin TX, US
Jason E. Lewis - Driftwood TX, US
David J. Knapp - Austin TX, US

Assignee:

Ketra, Inc. - Austin TX

International Classification:

H05B 33/08
G01R 31/44
G01J 3/50
H05B 37/02
G01J 1/42
G01J 3/46

Abstract:

An illumination device and method is provided herein for calibrating individual LEDs in the illumination device, so as to obtain a desired luminous flux and a desired chromaticity of the device over changes in drive current, temperature, and over time as the LEDs age. The calibration method may include subjecting the illumination device to a first ambient temperature, successively applying at least three different drive currents to a first LED to produce illumination at three or more different levels of brightness, obtaining a plurality of optical measurements from the illumination produced by the first LED at each of the at least three different drive currents, obtaining a plurality of electrical measurements from the photodetector and storing results of the obtaining steps within the illumination device to calibrate the first LED at the first ambient temperature. The plurality of optical measurements may generally include luminous flux and chromaticity, the plurality of electrical measurements may generally include induced photocurrents and forward voltages, and the calibration method steps may be repeated for each LED included within the illumination device and upon subjecting the illumination device to a second ambient temperature.

US Patent:

20150377699, Dec 31, 2015

Filed:

Jun 25, 2014

Appl. No.:

14/314451

Inventors:

- Austin TX, US
Jason E. Lewis - Driftwood TX, US
David J. Knapp - Austin TX, US

International Classification:

G01J 1/44

Abstract:

An illumination device and method is provided herein for calibrating individual LEDs in the illumination device, so as to obtain a desired luminous flux and a desired chromaticity of the device over changes in drive current, temperature, and over time as the LEDs age. The calibration method may include subjecting the illumination device to a first ambient temperature, successively applying at least three different drive currents to a first LED to produce illumination at three or more different levels of brightness, obtaining a plurality of optical measurements from the illumination produced by the first LED at each of the at least three different drive currents, obtaining a plurality of electrical measurements from the photodetector and storing results of the obtaining steps within the illumination device to calibrate the first LED at the first ambient temperature. The plurality of optical measurements may generally include luminous flux and chromaticity, the plurality of electrical measurements may generally include induced photocurrents and forward voltages, and the calibration method steps may be repeated for each LED included within the illumination device and upon subjecting the illumination device to a second ambient temperature.

US Patent:

20150382422, Dec 31, 2015

Filed:

Jun 25, 2014

Appl. No.:

14/314530

Inventors:

- Austin TX, US
Jason E. Lewis - Driftwood TX, US
David J. Knapp - Austin TX, US

International Classification:

H05B 33/08

Abstract:

An illumination device and method is provided herein for controlling individual light emitting diodes (LEDs) in an LED illumination device, so that a desired luminous flux and a desired chromaticity of the device can be maintained over time as the LEDs age. According to one embodiment, the method comprises applying drive currents to a plurality of LED chains substantially continuously to produce illumination, measuring a photocurrent induced on the photodetector in response to the illumination produced by each LED chain, one LED chain at a time, and received by the photodetector, and measuring a forward voltage developed across the photodetector by applying a non-operative drive current to the photodetector. For each LED chain, the method may further comprise determining an expected photocurrent value corresponding to the forward voltage measured across the photodetector and the drive current currently applied to the LED chain by applying one or more interpolation techniques to a table of stored calibration values correlating forward voltage and photocurrent to drive current at a plurality of different temperatures, and adjusting the drive current currently applied to the LED chain if a difference exists between the expected photocurrent value and the measured photocurrent.