Low-power wireless network beacon for turning off and on fluorescent lamps

• US 8,653,935 B2
• Filed: 09/30/2009
• Issued: 02/18/2014
• Est. Priority Date: 09/30/2009
• Status: Active Grant

• Current Assignee: IXYS Intl Limited (Littelfuse Incorporated)
• Original Assignee: IXYS CH GmbH (Littelfuse Incorporated)
• Inventors: Baker, Murray C.
• Primary Examiner(s): Lim, Steven
• Assistant Examiner(s): Knox, Kaleria
• Application Number:
  US12/587,062
• Publication Number:
  US 20110074623A1
• Time in Patent Office: 1,602 Days
• Field of Search: 340/418, 340/539.22, 340/540, 340/3.2, 315/294, 315/34, 370/336, 370/350, 324/754.23, 700/286, 455/41.2, 342/418, 710/10, 379/406.08
• US Class Current: 340/3.2
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: G08C 2201/12 Power saving techniques of remote control or controlled devices
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H05B 41/044 for lamp provided with pre-heating electrodes
• CPC Class Codes: H05B 47/115 by determining the presence or movement of objects or living beings
• CPC Class Codes: H05B 47/13 by using passive infrared detectors
• 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
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A low-power wireless network involves a plurality of RF-enabled fluorescent lamp starter units. In each of a plurality of intervals, a receiver of a starter unit operates in a receive mode during a beacon slot time, and for the majority of the rest of the interval operates in a low-power sleep mode. The starter unit wakes up and listens for a beacon each beacon slot time, regardless of whether a beacon is transmitted during that interval or not. A starter unit can be commanded to schedule a future action (for example, for a time between widely spaced synchronizing beacons) by making one of the beacons a scheduling beacon. The scheduling beacon includes a field that the starter unit uses to schedule the future action. If the scheduled action is to be canceled before the next widely spaced synchronizing beacon, then an action-canceling beacon is communicated in the next interval.

Claims

1. A method comprising:

(a) in each of a plurality of intervals placing a receiver of a receiver unit into a receive mode, and then listening for a beacon during a predefined beacon slot time within the interval, and placing the receiver into a low-power sleep mode for substantially all the rest of the interval, wherein beacons are received by the receiver during the beacon slot times of some of the intervals but wherein no beacon is received during the beacon slot times of other of the intervals;

(b) using the beacons received in (a) to synchronize the placing of the receiver into the receive mode with respect to the beacon slot times of the intervals; and

(c) using a value in a field in one of the beacons to schedule a future initiation of an action by the receiver unit, wherein the action is scheduled to be initiated after said one beacon at a time when no beacon is being received, wherein (a), (b) and (c) are carried out by the receiver unit, wherein the receiver unit includes a transmitter, wherein the receiver unit does not transmit from its transmitter unless being first commanded to by a beacon that includes a command, wherein the action is a turning off of a fluorescent lamp, and wherein the receiver unit is a fluorescent lamp starter unit.

2. The method of claim 1, further comprising:

(d) initiating a turning on of the fluorescent lamp in response to a receiving of another of the beacons.

3. The method of claim 2, wherein said one of the beacons in (c) includes a second field, and wherein a value of the second field identifies the action.

4. The method of claim 3, wherein the field in step (c) used to schedule the initiation of the action is a number of the intervals.

5. A method comprising:

(a) in each of a plurality of intervals placing a receiver of a receiver unit into a receive mode, and then listening for a beacon during a predefined beacon slot time within the interval, and placing the receiver into a low-power sleep mode for substantially all the rest of the interval, wherein beacons are received by the receiver during the beacon slot times of some of the intervals but wherein no beacon is received during the beacon slot times of other of the intervals;

(b) using the beacons received in (a) to synchronize the placing of the receiver into the receive mode with respect to the beacon slot times of the intervals;

(c) using a value in a field in one of the beacons to schedule a future initiation of an action by the receiver unit, wherein the action is scheduled to be initiated after said one beacon at a time when no beacon is being received, wherein (a), (b) and (c) are carried out by the receiver unit, wherein the receiver unit includes a transmitter, and wherein the receiver unit does not transmit from its transmitter unless being first commanded to by a beacon that includes a command, and

(d) transmitting the beacons from an occupancy detector, wherein the occupancy detector detects an absence of motion for a period of time and in response transmits said one of the beacons in (c), wherein the action scheduled in (c) is a turning off of a fluorescent lamp, and wherein the receiver unit is a fluorescent lamp starter unit.

6. The method of claim 5, wherein the receiver unit includes a transmitter, and wherein the receiver unit does not transmit from its transmitter unless commanded to by the occupancy detector.

7. A method comprising:

(a) in each of a plurality of intervals placing a receiver of a receiver unit into a receive mode, and then listening for a beacon during a predefined beacon slot time within the interval, and placing the receiver into a low-power sleep mode for substantially all the rest of the interval, wherein beacons are received by the receiver during the beacon slot times of some of the intervals but wherein no beacon is received during the beacon slot times of other of the intervals;

(b) using the beacons received in (a) to synchronize the placing of the receiver into the receive mode with respect to the beacon slot times of the intervals;

(c) using a value in a field in one of the beacons to schedule a future initiation of an action by the receiver unit, wherein the action is scheduled to be initiated after said one beacon at a time when no beacon is being received, wherein (a), (b) and (c) are carried out by the receiver unit, wherein the receiver unit includes a transmitter, and wherein the receiver unit does not transmit from its transmitter unless being first commanded to by a beacon that includes a command; and

(d) after the scheduling of (c) receiving another beacon onto the receiver unit, wherein said another beacon cancels the scheduling of the initiation of the action before the action can occur, wherein the receiver unit is a fluorescent lamp starter unit, wherein the action scheduled in (c) is a turning off of a fluorescent lamp, and wherein the scheduling is canceled in (d) before the fluorescent lamp is turned off.

8. The method of claim 7, further comprising:

(e) detecting motion on an occupancy detector and during the beacon slot time of the next interval transmitting a third beacon from the occupancy detector to the receiver unit, wherein the third beacon causes the receiver unit to turn on the fluorescent lamp.

9. A system comprising:

an occupancy detector that transmits a plurality of beacons, wherein each beacon is transmitted in a beacon slot time of a respective one of a plurality of intervals, wherein each beacon slot time has a predetermined location within a corresponding one of the intervals, wherein the occupancy detector transmits no beacon in some beacon slot times of some of the intervals but does transmit beacons in beacon slot times of other ones of the intervals; and

a fluorescent lamp starter unit that receives the beacons and uses the beacons to synchronize the placing of a receiver of the fluorescent lamp starter unit into a receive mode with respect to the beacon slot times of the intervals, wherein the receiver is placed into the receive mode during the beacon slot time of every one of the plurality of intervals, wherein the fluorescent lamp starter unit uses a value in a field of one of the beacons to schedule a future initiation of an action by a fluorescent lamp to which the fluorescent lamp starter unit is attached.

10. The system of claim 9, wherein the action is a turning off of a fluorescent lamp by the fluorescent lamp starter unit.

11. The system of claim 10, wherein a magnitude of the value determines a magnitude of time after said one of the beacons until the lamp is turned off.

12. The system of claim 9, wherein the fluorescent lamp starter unit does not transmit any signal to the occupancy detector unless it is first commanded to by the occupancy detector.

13. A fluorescent lamp starter unit comprising:

a Radio Frequency (RF) transceiver that receives a beacon; and

means for using a value in a field of the beacon to schedule a future turning off of a fluorescent lamp by the fluorescent lamp starter unit, wherein a magnitude of the value determines a magnitude of time after the beacon is received until the fluorescent lamp starter unit is to turn off the fluorescent lamp.

14. The fluorescent lamp starter unit of claim 13, wherein the means is also for using beacons to synchronize times when the RF transceiver is in a receive mode so that the times when the RF transceiver is in the receive mode coincide with times when the beacons occur.

15. The fluorescent lamp starter unit of claim 13, wherein the means is also for controlling the fluorescent lamp starter unit such that the fluorescent lamp starter unit does not use its RF transceiver to transmit unless the fluorescent lamp starter unit is first commanded to by a beacon.