WAKE-UP OF LIGHT SENSOR IN A LIGHTING SYSTEM

• US 20120074852A1
• Filed: 05/28/2010
• Published: 03/29/2012
• Est. Priority Date: 06/04/2009
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Delnoij, Roger Peter Anna
• Granted Patent: US 8,638,036 B2
• Time in Patent Office: Days
• US Class Current: 315/158
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: H05B 47/19 via wireless transmission
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A wireless light sensor, being part of a lighting system, has a sensor element generating a light measuring signal, a microcontroller coupled to the sensor element, and a radio communication device coupled to the microcontroller. The microcontroller has an active mode and a sleeping mode. The light sensor further has a wake-up circuit which determines a rate of change of the light measuring signal, when the microcontroller is in the sleeping mode. The wake-up circuit brings the microcontroller from the sleeping mode into the active mode, when the rate of change of the light measuring signal exceeds a predetermined threshold.

Claims

1. A wireless light sensor comprising

a sensor element generating a light measuring signal;

a microcontroller coupled to the sensor element, the microcontroller having an active mode and a sleeping mode; and

a radio communication device coupled to the microcontroller, wherein the light sensor further comprises a wake-up circuit configured for

determining a rate of change of the light measuring signal, when the microcontroller is in the sleeping mode, and

bringing the microcontroller from the sleeping mode into the active mode, when the rate of change of the light measuring signal exceeds a predetermined threshold.

2. The light sensor of claim 1, wherein the wake-up circuit comprises a comparator comparing a momentary value of the light measuring signal with an average value of the light measuring signal.

3. The light sensor of claim 1, wherein, when the microcontroller is in a sleeping mode, the light sensor is configured for periodically bringing the microcontroller in the active mode and transmitting data representative of the light measuring signal through the radio communication device, and bringing the microcontroller in the sleeping mode again.

4. The light sensor of claim 1, wherein a time period between subsequent active modes of the microcontroller is at least one minute, in particular at least five minutes.

7. A lighting system, comprising:

at least one light source;

a controller for controlling the light source; and

the light sensor of claim 1.

8. The lighting system of claim 7, wherein, after the micro controller has been brought from the sleeping mode into the active mode, the light sensor is configured to communicate with the controller to verify the status of the light source to confirm the active mode of the light sensor.

5. A method of operating a wireless light sensor, the light sensor comprising

a sensor element generating a light measuring signal;

a microcontroller coupled to the sensor element, the microcontroller having an active mode and a sleeping mode, and

a radio communication device coupled to the microcontroller,

wherein the microcontroller has an active mode and a sleeping mode, and wherein the method comprises

determining a rate of change of the light measuring signal, when the microcontroller is in the sleeping mode, and

bringing the microcontroller from the sleeping mode into the active mode, if the rate of change of the light measuring signal exceeds a predetermined threshold.

6. The method of claim 5, further comprising, when the microcontroller is in a sleeping mode, periodically bringing the microcontroller in the active mode and transmitting data representative of the light measuring signal, and bringing the microcontroller in the sleeping mode again.