LOW-POWER RADIO-FREQUENCY RECEIVER

• US 20120281606A1
• Filed: 03/08/2012
• Published: 11/08/2012
• Est. Priority Date: 03/11/2011
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Cooney, Andrew Karl, Mierta, Justin J., Crafts, Jordan H., Dejonge, Stuart W., Knode, Galen E., Lenz, Jonathan T., Mosebrook, Donald R.
• Granted Patent: US 10,041,292 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: E06B 2009/2625 Pleated screens, e.g. concertina- or accordion-like
• CPC Class Codes: E06B 2009/6818 using sensors
• CPC Class Codes: E06B 2009/6872 using counters to determine shutter position
• CPC Class Codes: E06B 9/32 Operating, guiding, or securing devices therefor operation of tilting bars E06B9/307
• CPC Class Codes: E06B 9/322 Details of operating devices, e.g. pulleys, brakes, spring drums, drives operating devices E06B9/68 ; devices of general interest specially adapted or mounted for storing and repeatedly paying-out and re-storing lengths of material B65H75/34
• CPC Class Codes: E06B 9/38 Other details
• CPC Class Codes: E06B 9/62 Counterweighting arrangements E06B9/60 takes precedence
• CPC Class Codes: E06B 9/68 Operating devices or mechanisms, e.g. with electric drive
• CPC Class Codes: E06B 9/70 comprising an electric motor positioned outside the roller
• CPC Class Codes: E06B 9/72 comprising an electric motor positioned inside the roller
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 52/0225 using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 52/0235 where the received signal is a power saving command
• CPC Class Codes: H04W 52/0238 where the received signal is an unwanted signal, e.g. interference or idle signal
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: H04W 52/0287 changing the clock frequency of a controller in the equipment
• CPC Class Codes: Y02A 30/24 Structural elements or technologies for improving thermal insulation
• CPC Class Codes: Y02B 80/00 : Architectural or constructional elements improving the thermal performance of buildings
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

A low-power RF receiver has a decreased current consumption. The receiver may be used in control devices, such as battery-powered motorized window treatments and two-wire dimmer switches. The receiver uses an RF sub-sampling technique to check for RF signals and then puts the receiver to sleep for a sleep time that is longer than a packet length of a transmitted packet to conserve battery power. The receiver compares detected RF energy to a threshold that may be increased to decrease the sensitivity of the receiver and increase the battery lifetime. After detecting an RF signal, the receiver is put to sleep for a snooze time that is longer than the sleep time and just slightly shorter than the time between two consecutive transmitted packets.

Claims

1. A load control device for controlling an electrical load receiving power from a power source in response to RF signals transmitted by an RF transmitter, the RF transmitter adapted to transmit a number of sequential digital messages at a predetermined transmission rate, each of the digital messages including the same command and characterized by a packet length, the load control device comprising:

an RF receiver adapted to receive at least one of the sequential digital messages, the RF receiver enabled for a sample time period to determine if the RF transmitter is transmitting one of the digital messages, the RF receiver entering a sleep mode for a sleep time period between consecutive sample time periods; and

a controller operatively coupled to the RF transceiver for receiving the at least one of the sequential digital messages, the controller operable to control the load in response to the received digital message;

wherein the sleep time period of the RF receiver is longer than the packet length of each of the digital messages.

2. The load control device of claim 1, further comprising:

a battery for powering the controller and the RF receiver.

3. The load control device of claim 2, wherein the controller can be controlled into a sleep mode in which the controller consumes less power than in a normal mode.

4. The load control device of claim 3, wherein the RF receiver is operable to determine if detected RF energy exceeds a detect threshold, the RF receiver operable to wake up the controller from the sleep mode to enter the normal mode in response to determining that the detected RF energy exceeds the detect threshold.

5. The load control device of claim 4, wherein the controller is operable to put the RF receiver and the controller to sleep for a snooze time in response to determining that the detected RF energy exceeds the detect threshold, the RF receiver and the controller waking up after the snooze time, such that the controller is operable to receive one of the digital messages.

6. The load control device of claim 5, wherein the snooze time is slightly less than a break time between two subsequent ones of the sequential digital messages.

7. The load control device of claim 4, wherein the controller is operable to adjust the detect threshold of the RF receiver whereby the detect threshold can be increased to prevent noise signals from causing the RF receiver to wake up the controller thereby conserving battery power.

8. The load control device of claim 7, wherein the controller is operable to adjust the detect threshold from an extended range threshold close to a noise floor to an extended battery mode threshold greater than the extended range threshold.

9. The load control device of claim 2, wherein the electrical load comprises a motor for adjusting a covering material of a motorized window treatment, the load control device comprising:

a motor drive circuit coupled to the motor for driving the motor to thus open and close the covering material.

10. The load control device of claim 9, further comprising:

a drive shaft; and

at least one lift cord rotatably received around the drive shaft and extending to a bottom of the covering material for raising and lowering the covering material;

wherein the motor is operatively coupled to the drive shaft such that the motor is operable to raise and lower the covering material by rotating the drive shaft.

11. The load control device of claim 2, further comprising:

at least visual indicator operable to display an indication of the state of the load.

12. The load control device of claim 11, wherein the load control device comprises a battery-powered remote control.

13. The load control device of claim 2, wherein the load control device comprises a temperature control device operable to control a heating and/or cooling system in response to the received digital message.

14. The load control device of claim 1, further comprising:

a controllably conductive device adapted to be coupled in series electrical connection between the source and the load for controlling the power delivered to the load;

wherein the controller is operatively coupled to a control input of the controllably conductive device for controlling the power delivered to the load in response to the received digital message.

15. The load control device of claim 14, further comprising:

a power supply coupled in parallel electrical connection with the controllably conductive device, the power supply operable to conduct a charging current through the load in order to generate a DC supply voltage for powering the controller.

16. The load control device of claim 14, further comprising:

a ground terminal adapted to be coupled to earth ground; and

a power supply adapted to conduct a charging current through the ground terminal in order to generate a DC supply voltage for powering the controller.

17. The load control device of claim 14, wherein the load comprises a lighting load and the load control device comprises a dimmer switch for controlling the amount of power delivered to the lighting load to adjust the intensity of the lighting load.

18. The load control device of claim 1, wherein a packet break time period exists between any two consecutive packets, the sample time period and the sleep time period of the RF receiver sized such that at least one of the number of sequential digital messages coincides with one of the sample time period of the RF receiver.

19. An RF communication system comprising:

an RF transmitter adapted to transmit a number of sequential digital messages at a predetermined transmission rate, each of the digital messages including the same command and characterized by a packet length; and

an RF receiver adapted to receive at least one of the sequential digital messages, the RF receiver enabled for a sampling time to determine if the RF transmitter is transmitting one of the digital messages, the RF receiver entering a sleep mode for a sleep time period between consecutive sample time periods;

wherein the sleep time period of the RF receiver is longer than the packet length of each of the digital messages.

20. The RF communication system of claim 19, further comprising:

a plurality of control devices operable to receive RF signals transmitted on a first frequency.

21. The RF communication system of claim 20, further comprising:

a signal repeater operable to receive a first RF signal transmitted on the first frequency by one of the control devices, the signal repeater operable to determine that the first RF signal is intended for the RF receiver, the signal repeater operable to change transmission frequencies and transmit a second RF signal related to the first RF signal to the RF receiver on a second frequency different than the first frequency.

22. The RF communication system of claim 21, wherein the signal repeater is operable to determine the number of the plurality of control devices, and to transmit the second RF signal to the RF receiver on the second frequency only if the number of control devices exceeds a threshold amount.

23. The RF communication system of claim 20, further comprising:

a first signal repeater operable to receive a first RF signal transmitted on the first frequency by one of the control devices; and

a second signal repeater coupled to the first signal repeater via a communication link;

wherein the first signal repeater is operable to transmit a digital message to the second signal repeater via the communication link in response to receiving the first RF signal, the second signal repeater operable to transmit a second RF signal to the RF receiver on a second frequency different than the first frequency in response to receiving the digital message from the first signal repeater via the communication link.

24. The RF communication system of claim 23, wherein the communication link comprises a wired communication link.

25. The RF communication system of claim 20, wherein the RF transmitter is operable to transmit the sequential digital messages to the RF receiver on a second frequency different than the first frequency.

26. The RF communication system of claim 19, wherein the RF receiver comprises a battery for powering the RF receiver.

27. The RF communication system of claim 26, wherein the RF receiver comprises a battery-powered motorized window treatment for adjusting the position of a covering material.

28. The RF communication system of claim 26, wherein the RF receiver comprises a battery-powered remote control having a visual indicator.

29. The RF communication system of claim 26, wherein the RF receiver comprises a temperature control device operable to control a heating and/or cooling system.

30. The RF communication system of claim 19, wherein the RF receiver comprises a load control device adapted to be coupled in series electrical connection between an AC power source and an electrical load for controlling the power delivered to the load.

31. The RF communication system of claim 30, wherein the load control device comprises a two-wire device adapted to be coupled in series electrical connection between the AC power source and the electrical load without a connection to the neutral side of the AC power source.

32. The RF communication system of claim 30, wherein the load control device comprises a ground terminal adapted to be coupled to earth ground, the load control device operable to conduct a charging current for an internal power supply through the ground terminal.

33. The RF communication system of claim 19, wherein the RF transmitter comprises one of a battery-powered remote control, an occupancy sensor, a vacancy sensor, a daylight sensor, a temperature sensor, a humidity sensor, a security sensor, a proximity sensor, a keypad, a key fob, a cell phone, a smart phone, a tablet, a personal digital assistant, a personal computer, a timeclock, an audio-visual control, a safety device, and a central control transmitter.

34. The RF communication system of claim 19, wherein a packet break time period exists between any two consecutive packets, the sample time period and the sleep time period of the RF receiver sized such that at least one of the number of sequential digital messages coincides with one of the sample time period of the RF receiver.

35. A wireless signal receiver comprising:

a wireless receiver circuit for detecting transmitted signals transmitted in a predetermined number of packets, where each packet comprises the same data, there being a packet time and a time between packets substantially longer than the packet time; and

a control circuit for turning on the wireless receiver circuit for an on-time, the on-time being substantially less than an off-time of the wireless receiver circuit, the on-time of the wireless receiver circuit being substantially less than the packet time and the off-time between on-times being less than the time between packets;

wherein the off-time is selected so that within the plurality of packets, the on-time will coincide with the packet time to ensure that the wireless receiver circuit detects at least one packet during the transmission of the predetermined number of packets if packets are being transmitted.

36. The wireless signal receiver of claim 35, wherein the wireless signals are RF signals.

37. The wireless signal receiver of claim 36, further comprising:

an antenna coupled to the RF receiver circuit; and

a filter circuit comprising a SAW filter coupled between the antenna and the RF receiver circuit for filtering out frequencies outside of a defined frequency range;

wherein said RF receiver circuit remains on if an RF signal is detected, and said filter circuit prevent said RF receiver circuit from remaining on or turning on again for RF signals outside of said frequency range, thereby conserving battery power.

38. The wireless signal receiver of claim 37, wherein the RF receiver circuit is operable to turn on a control circuit in response to detecting the RF signal.

39. The wireless signal receiver of claim 35, wherein the on-time is approximately 0.1 msec, the off-time is approximately 40 msec, the packet time is approximately 5 msec and the time between packets is approximately 75 msec.

40. The wireless signal receiver of claim 39, wherein the predetermined number of packets comprises twelve.

41. The wireless signal receiver of claim 35, further wherein the wireless signal receiver is battery powered and further comprising an adaptive circuit for changing the off-time of said receiver circuit to optimize battery life.

42. A method of communicating digital messages in a load control system, the method comprising:

transmitting a number of sequential digital messages at a predetermined transmission rate, each of the digital messages including the same command and characterized by a packet length;

enabling an RF receiver for a sample time period to determine if the RF transmitter is transmitting one of the digital messages; and

putting the RF receiver in a sleep mode for a sleep time period between consecutive sample time periods;

wherein the sleep time period of the RF receiver is longer than the packet length of each of the digital messages.

43. The method of claim 42, further comprising:

the RF receiver determining if detected RF energy exceeds a detect threshold; and

the RF receiver waking up a controller from a sleep mode to enter a normal mode in response to determining that the detected RF energy exceeds the detect threshold.

44. The method of claim 43, further comprising:

the controller putting the RF receiver and the controller to sleep for a snooze time in response to determining that the detected RF energy exceeds the detect threshold;

the RF receiver and the controller waking up after the snooze time, the snooze time slightly less than a break time between two subsequent ones of the sequential digital messages; and

the controller subsequently receiving at least one of the digital messages.

45. The method of claim 44, further comprising:

the controller controlling the power delivered to an electrical load in response to the received digital message.

46. The method of claim 43, further comprising:

the controller adjusting the detect threshold of the RF receiver whereby the detect threshold can be increased to prevent noise signals from causing the RF receiver to wake up the controller thereby conserving battery power.

47. The method of claim 42, wherein a packet break time period exists between any two consecutive packets, the sample time period and the sleep time period of the RF receiver sized such that at least one of the number of sequential digital messages coincides with one of the sample time period of the RF receiver.

48. A wireless signal receiver circuit for detecting wireless control signals and having an on/off operation to conserve power comprising:

a control circuit;

a wireless receiver having an on state when it consumes power and an off state when it consumes less power than consumed in the on state, the on state having a duration substantially shorter than the off state, whereby the wireless receiver receives wireless control signals during the on state to be processed by the control circuit, the wireless control signals being sent in packets with a packet time such that there is a predefined time between packets; and

wherein the wireless receiver is operable to periodically be in the on state for a sample time substantially less than the packet time to detect a wireless control signal, whereby upon detecting a first packet during the sample time, the wireless receiver is operable to enter the off state to conserve power for an amount of time slightly less than the predefined time between packets, to subsequently turn on and remain on until a succeeding packet starts to be received, and to turn off after the succeeding packet is fully received.

49. The wireless signal receiver circuit of claim 48, wherein the control circuit has an on state when it consumes power and an off state when it consumes less power than consumed in the on state, the wireless receiver operable to cause the control circuit to enter the on state in response to detecting the wireless control signals.

50. The wireless signal receiver circuit of claim 49, wherein upon the wireless receiver detecting the first packet, the control circuit is operable to determine that the wireless receiver did not receive the first packet in its entirety.

51. The wireless signal receiver circuit of claim 50, wherein upon the control circuit determining that the wireless receiver did not receive the first packet in its entirety, the control circuit is operable to cause the wireless receiver to enter the off state and to enter the off state itself to conserve power for an amount of time slightly less than the predefined time between packets.

52. The wireless signal receiver circuit of claim 48, wherein the wireless control signals are RF signals.

53. The wireless signal receiver circuit of claim 48, wherein the control circuit comprises a microprocessor.

54. The wireless signal receiver circuit of claim 48, wherein if the wireless receiver does not detect a wireless signal during the on state, the wireless receiver turns off until a next on state.

55. A battery-powered wireless device comprising:

a control circuit having an on state when it consumes power and an off state when it consumes less power than consumed in the on state; and

a wireless receiver circuit operable to periodically check for wireless signals, the wireless receiver circuit having a detect threshold wherein the wireless receiver circuit is operable to determine whether a wireless signal exceeds the detect threshold, the receiver circuit operable to cause the control circuit to be in on state in response to determining that a wireless signal exceeds the detect threshold;

wherein the control circuit is further operable to adjust the detect threshold of the wireless receiver circuit whereby the detect threshold can be increased to prevent noise signals from causing the wireless receiver circuit to turn on the control circuit thereby conserving battery power.

56. The battery powered wireless receiver of claim 55, wherein there are at least two detect thresholds comprising an extended range threshold close to a noise floor and an extended battery mode threshold above the extended range threshold.

57. A system for conserving battery power of a battery powered wireless signal receiver comprising:

a wireless signal receiver that periodically turns on to determine if a wireless signal is being transmitted, the wireless signal receiver being capable of receiving on any of multiple channels, the wireless signal receiver including a control circuit that determines if the wireless signal is intended for the wireless signal receiver; and

a transceiver circuit for retransmitting said wireless signals, the transceiver circuit determining a number of transmitted wireless signals, and if the number exceeds a threshold amount, said transceiver circuit communicating with the wireless signal receiver to change the channel of communication to an alternate channel and retransmitting wireless signals intended for the wireless signal receiver on the alternate channel, whereby the wireless signal receiver will receive fewer wireless signals on the alternate channel, thereby remaining on for less time and reducing battery power consumption.

58. The system of claim 57, wherein the transceiver comprises a repeater for retransmitting the wireless signals from a plurality of transmitting devices.

59. The system of claim 58, wherein the repeater automatically switches to a less used alternate channel when the threshold amount is exceeded.

60. The system of claim 58, wherein the plurality of transmitting devices include at least one transmitter for controlling a battery powered motorized window treatment.

61. The system of claim 58, wherein the multiple channels have different carrier frequencies.

62. The system of claim 57, wherein the wireless signals are RF signals.

63. A wireless control system comprising:

a first wireless signal receiver capable of receiving on wireless signals on a first channel;

a second wireless signal receiver that periodically turns on to determine if wireless signals are being transmitted, the second wireless signal receiver being capable of receiving on wireless signals on a second channel; and

a transceiver circuit for retransmitting said wireless signals, said transceiver circuit operable to receive a first wireless signal on the first channel and to determine that the first wireless signal contains control information intended for the second wireless signal receiver, the transceiver circuit operable to change its channel of communication from the first channel to the second channel, the transceiver circuit transmitting the control information in a second wireless signal to the second wireless signal receiver on the second channel.

64. The wireless control system of claim 63, wherein the transceiver circuit is operable to change its channel of communication from the second channel to the first channel, after transmitting the control information in the second wireless signal to the second wireless signal receiver on the second channel.