Lighting system including photonic emission and detection using light-emitting elements

• US 20060028156A1
• Filed: 08/04/2005
• Published: 02/09/2006
• Est. Priority Date: 08/06/2004
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: TIR Technology LP
• Inventors: Jungwirth, Paul
• Granted Patent: US 7,329,998 B2
• Time in Patent Office: Days
• US Class Current: 315/312
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/37 Converter circuits

Abstract

The present invention provides a system and method for generating light using light-emitting elements and detecting the intensity and spectral power distribution of light using the same light-emitting elements as spectrally sensitive photodetectors. The light-emitting elements function in two modes, an ON mode and an OFF mode, wherein in the ON mode the light-emitting elements are activated and emit light of a particular frequency or range of frequencies. When in the OFF mode, the light-emitting elements are deactivated, wherein they do not emit light but serve to detect photons incident upon them thus generating an electrical signal representative of the intensity and spectral power distribution of the incident photons. The detected signal from the deactivated light-emitting elements can be used to provide photonic feedback to a lighting system, and thereby may be used to control the brightness and colour balance of the lighting system. In addition, the light-emitting elements may be arranged such that no spectrally selective filters or optics are necessary to block or focus light onto the light-emitting elements when in the detection or OFF mode.

Claims

1. A lighting system comprising:

a) one or more light-emitting elements for emission and detection of light;

b) a control means for switching the one or more light emitting elements between a first emission mode and a second detection mode, the control means adapted for connection to a power source; and

c) a signal processing means operatively connected to the one or more light-emitting elements, the signal processing means for receiving one or more first signals generated by the one or more light-emitting elements in response to light incident thereupon when in the second detection mode.

2. The lighting system according to claim 1, further comprising a conversion device operatively connected to the one or more light-emitting elements and the signal processing means, the conversion device configured to convert the one or more first signals from a photocurrent to a voltage.

3. The lighting system according to claim 2, wherein the signal processing means is operatively connected to a feedback means, the feedback means providing the control means with one or more parameters for controlling operation of the one or more light-emitting elements based on one or more second signals received from the signal processing means, the one or more second signals representative of the one or more first signals.

4. The lighting system according to claim 3, wherein one or more of the signal processing means, the feedback means and the control means are integrated into a microprocessor or a field programmable gate array.

5. The lighting system according to claim 2, wherein the signal processing means is an analog-to-digital converter.

6. The lighting system according to claim 2,wherein the signal processing means comprises signal-conditioning circuitry for enhancing the one or more first signals generated by the one or more light-emitting elements.

7. The lighting system according to claim 6, wherein the signal-conditioning circuitry comprises an amplifier to boost or scale the one or more first signals.

8. The lighting system according to claim 2, wherein the signal processing means comprises filtering circuitry for modifying a signal to noise ratio associated with the one or more first signals generated by the one or more light-emitting elements.

9. The lighting system according to claim 8, wherein the filtering circuitry comprises one or more filters selected from the group comprising band pass, high pass and low pass.

10. The lighting system according to claim 2, further comprising sample-and-hold circuitry operatively connected to the one or more light-emitting elements and the signal processing means, said sample-and-hold circuitry for capturing the one or more first signals generated by the one or more light-emitting elements.

11. The lighting system according to claim 2, further comprising a filter operatively coupled to the one or more light-emitting elements, the filter configured to be substantially transparent to the light emitted by the one or more light-emitting elements when in the first emission mode and configured to modify spectral responsivity of the one or more light-emitting elements when operating in the second detection mode.

12. The lighting system according to claim 2, wherein the conversion device is an operational amplifier circuit.

13. The lighting system according to claim 12, wherein the operational amplifier circuit comprises a gain resistor configured based on predefined minimum and maximum light intensity levels, the operational amplifier circuit thereby generating output within a desired range.

14. The lighting system according to claim 12, wherein the operational amplifier circuit comprises a potentiometer thereby providing a means for dynamically adjusting gain of the operational amplifier circuit.

15. The lighting system according to claim 12, wherein the operational amplifier circuit comprises a diode for damping ringing upon switching of the one or more light emitting elements from the first emission mode to the second detection mode.

16. The lighting system according to claim 2, further comprising a sense resistor operatively connected to the one or more light-emitting elements.

17. The lighting system according to claim 2, wherein the signal processing means is operatively connected to a colorimeter for determining luminous intensity and chromaticity of the light incident upon the one or more light-emitting elements.

18. The lighting system according to claim 2, wherein the one or more light-emitting elements comprises a plurality of light-emitting elements configured to emit light of one or more colours.

19. The lighting system according to claim 18, wherein the one or more colours includes red, green and blue.

20. The lighting system according to claim 19, wherein the one or more colours further includes amber.

21. The lighting system according to claim 4, wherein the microprocessor is configured to account for spectral responsivity of each of the one or more light-emitting elements, wherein the spectral responsivity is dependent on emission colour of each one or more light-emitting elements emission colour.

22. The lighting system according to claim 21, wherein each of the one or more light-emitting elements are polled for respective signals representative of the light incident thereon.

23. The lighting system according to claim 2, wherein the control means switches the one or more light-emitting elements using a digital switching signal.

24. The lighting system according to claim 23, wherein the digital switching signal is a pulse width modulation signal or a pulse code modulation signal.

25. The lighting system according to claim 24, wherein the pulse width modulation signal has a switching frequency of less than or equal to 5 kHz.

26. The lighting system according to claim 24, wherein the pulse width modulation signal has a switching frequency of greater than or equal to 5 kHz, wherein the control means comprises a mechanism to over-ride the pulse width modulation signal and thereby place one or more of said light-emitting elements into the second detection mode for multiple cycles, thereby providing sufficient time to detect the signal generated by the one or more light-emitting elements in response to light incident thereupon.