Lighting system having a remotely controlled electric lamp and an infrared remote controller with improved infrared filter

• US 5,506,715 A
• Filed: 04/12/1995
• Issued: 04/09/1996
• Est. Priority Date: 10/28/1993
• Status: Expired due to Fees

• Current Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Zhu, Joshua S.
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US08/419,742
• Time in Patent Office: 363 Days
• Field of Search: 359/142, 359/144, 359/147, 359/157, 359/168, 359/189, 359/193, 359/111, 340/825-872, 348/342, 485/307, 362/233, 362/293, 315/149, 315/151, 250/214 B, 364/724.01
• US Class Current: 398/111
• CPC Class Codes: G08C 23/04 using light waves, e.g. infrared
• CPC Class Codes: G08C 25/00 Arrangements for preventing or correcting errors; Monitoring arrangements
• CPC Class Codes: H03K 5/1252 Suppression or limitation of noise or interference specially adapted for transmission systems H04B15/00, H04L25/08

Abstract

A lighting system having an electric lamp controlled by an infrared remote controller. The remote controller incorporates a commercially available transmitter and receiver which reliably functions in the presence of infrared noise having frequencies at and about the carrier frequency of the transmitted signal. The remote controller receiver outputs a demodulated signal and a filter acts on the demodulated signal to remove noise present in the demodulated signal caused by the electric lamp by comparing measured time intervals between leading and trailing edges of the demodulated signal to predetermined values defining data elements.

Claims

1. In a lighting system of the type having an electric lamp and a remote controller for controlling the electric lamp, the remote controller including a transmitter which transmits information via modulated infrared light and a receiver which receives the infrared light, the receiver including means for demodulating the information therefrom,

decoding means for decoding the demodulated information coupled to the receiver and including filter means, the filter means for operating on the demodulated information for removing noise caused by infrared light from the electric lamp, the demodulated information including a plurality of leading and trailing edges, the transmitted information having a data element defined in the demodulated information by a leading edge followed by a trailing edge within a predetermined time range, and the noise is present in the demodulated information as a leading edge followed by a trailing edge at random time intervals, and said filter means filters noise from the demodulated information by determining which leading and trailing edges correspond to noise and which leading and trailing edges correspond to the date element, and wherein the filter means is software within a microcontroller which controls operation of the electric lamp.

2. The lighting system according to claim 1, wherein said filter means comprises:

detecting means for detecting the leading and trailing edges in the demodulated information;

measuring means coupled to the detecting means for measuring the time interval between a detected leading edge and subsequently detected trailing edges;

comparing means coupled to the measuring means for comparing the measured time intervals to the predetermined time range; and

means for accepting the detection of a trailing edge as a decoded data element if a measured time interval is within the predetermined time range defining the data element and for rejecting the detection of a trailing edge as noise if the measured time interval falls outside of the predetermined time range, said means for accepting and rejecting being coupled to the comparing means.

3. The lighting system according to claim 2, wherein the transmitted information includes a plurality of data elements each defined by distinct predetermined time ranges between a leading edge and a subsequent trailing edge, and said comparing means compares the measured time intervals with each of the distinct time ranges.

4. The lighting system according to claim 3, wherein the transmitted information includes a first set of data elements and a second, inverted set of data elements in which each data element is the inverted logical equivalent of a respective data element in the first set of data elements, and said filter means further comprises:

means for inverting the decoded data elements of the second, inverted set of data elements, said means for inverting being coupled to the means for accepting and rejecting; and

means for detecting inconsistencies between each decoded data element of the first set of data elements and the respective data element of the second set of data elements, said means for detecting inconsistencies being coupled to the means for inverting.

5. The lighting system according to claim 4, further comprising means for shaping the demodulated information into a square wave signal and wherein said filter means acts on the square wave signal, and wherein the means for shaping is coupled to the means for demodulating.

6. The lighting system according to claim 5, further comprising lamp drive means for driving said electric lamp in a frequency range of between about 20 khz and about 120 khz, said lamp drive means being connected to said receiver and responsive to the demodulated, filtered information and wherein said transmitter transmits infrared light with a carrier frequency within this range.

7. The lighting system according to claim 6, wherein said electric lamp is a fluorescent lamp.

8. The lighting system according to claim 1, further comprising lamp drive means for driving said electric lamp in a frequency range of between about 20 khz and about 120 khz, said lamp drive means being connected to said receiver and responsive to the demodulated, filtered information and wherein said transmitter transmits infrared light with a carrier frequency within this range.

9. The lighting system according to claim 1, wherein said electric lamp is a fluorescent lamp.

10. The lighting system according to claim 1, wherein the filter means is software within the microcontroller.

11. In a remote control system of the type including a transmitter which transmits information via a modulated infrared light and a receiver which receives the infrared light from said transmitter, the receiver including means for demodulating the transmitted information therefrom, the improvement comprising:

decoding means coupled to the receiver and including filter means for operating on the demodulated information for removing noise caused by an electric lamp emitting infrared light, the demodulated information including a plurality of leading and trailing edges, the transmitted information having a data element defined in the demodulated information by a leading edge followed by a trailing edge within a predetermined time range, and the noise is present in the demodualted information as a leading edge followed by a trailing edge at random time intervals, and said filter means filters noise from the demodulated information by determining which leading and trailing edges correspond to noise and which leading and trailing edges correspond to the date element, and wherein the filter means is software in a microcontroller which controls operation of an appliance.

12. The remote control system according to claim 11, wherein said filter means comprises:

detecting means for detecting the leading and trailing edges in the demodulated information;

measuring means coupled to the detecting means for measuring the time interval between a detected leading edge and subsequently detected trailing edges;

comparing means coupled to the measuring means for comparing the measured time intervals to the predetermined time range; and

means for accepting the detection of a trailing edge as a decoded data element if a measured time interval is within the predetermined time range defining the data element and for rejecting the detection of a trailing edge as noise if the measured time interval falls outside of the predetermined time range, said means for accepting and rejecting being coupled to the comparing means.

13. The remote control system according to claim 12, wherein the transmitted information includes a plurality of data elements each defined by distinct predetermined time ranges between a leading edge and a subsequent trailing edge, and said comparing means compares the measured time intervals with each of the distinct time ranges.

14. The remote control system according to claim 13, wherein the transmitted information transmitted by the transmitter includes a first set of data elements and a second, inverted set of data elements in which each data element is the inverted logical equivalent of a respective data element in the first set of data elements, and said filter means further comprises:

means for inverting the decoded data elements of the second, inverted set of data elements, said means for inverting being coupled to the means for accepting and rejecting; and

means for detecting inconsistencies between each decoded data element of the first set of data elements and the respective data element of the second set of data elements said means for detecting inconsistencies being coupled to the means for inverting.

15. The remote control system according to claim 14, further comprising means for shaping the demodulated information into a square wave signal and wherein said filter means acts on the square wave signal, and wherein the means for shaping is coupled to the means for demodulating.

16. The remote control system according to claim 15, wherein said transmitter transmits infrared light having a carrier frequency of between about 20 khz and about 120 khz and said filter means is effective for filtering noise from the demodulated information caused by infrared light from an electric lamp operated, between about 20 khz and about 120 khz.

17. The remote control system according to claim 16, wherein said filter is effective for filtering noise caused by a fluorescent lamp operated within said frequency range of about 20 khz and about 120 khz.

18. The remote control system according to claim 11, wherein said transmitter transmits infrared light having a carrier frequency of between about 20 kHz and about 120 kHz and said filter means is effective for filtering noise from the demodulated information caused by infrared light from an electric lamp operated between about 20 khz and about 120 khz.

19. The remote control system according to claim 11, wherein said filter means is effective for filtering noise in the demodulated signal caused by the infrared light from a fluorescent lamp.

20. A receiver for an infrared remote controller operated in the presence of an electric lamp which emits infrared light, said receiver comprising:

means for receiving an infrared transmission signal which includes information encoded by modulation of the transmission signal, said receiving means also being responsive to the infrared light from the electric lamp;

demodulating means for demodulating the infrared signals received by said receiving means;

filtering means for filtering noise in the demodulated signals caused by the infrared light from the electric lamp; and

decoding means for decoding the transmitted information from the demodulated signals, the demodulated information including a plurality of leading and trailing edges, the transmitted information having a data element defined in the demodulated information by a leading edge followed by a trailing edge within a predetermined time range, and the noise is present in the demodulated information as a leading edge followed by a trailing edge at random time intervals, and said filter means filters noise from the demodulated information by determining which leading and trailing edges correspond to noise and which leading and trailing edges correspond to the data element, and wherein the filtering means is software in a microcontroller which controls the electric lamp.

21. The receiver according to claim 20, wherein the filter means comprises:

detecting means for detecting the leading and trailing edges in the demodulated information;

measuring means coupled to the detecting means for measuring the time interval between a detected leading edge and subsequently detected trailing edges;

comparing means coupled to the measuring means for comparing the measured time intervals to the predetermined time range; and

means for accepting the detection of a trailing edge as a decoded data element if a measured time interval is within the predetermined time range defining the data element and for rejecting the detection of a trailing edge as noise if the measured time interval falls outside of the predetermined time range, said means for accepting and rejecting being coupled to the comparing means.

22. The receiver according to claim 21, wherein the transmitted information includes a plurality of data elements each defined by distinct predetermined time ranges between a leading edge and a subsequent trailing edge, and said comparing means compares the measured time intervals with each of the distinct time ranges.

23. The receiver according to claim 22, wherein the transmitted information includes a first set of data elements and a second, inverted set of data elements in which each data element is the inverted logical equivalent of a respective data element in the first set of data elements, and said filter means further comprises:

means for inverting the decoded data elements of the second, inverted set of data elements, said means for inverting coupled to the means for accepting and rejecting; and

means for detecting inconsistencies between each decoded data element of the first set of data elements and the respective data element of the second set of data elements said means for detecting inconsistencies being coupled to the means for inverting.

24. The receiver according to claim 23, further comprising means for shaping the demodulated signals into a square wave signal, and wherein said filter means acts on the square wave signal, and wherein the means for shaping is coupled to the means for demodulating.

25. The receiver according to claim 24, wherein the transmission signal has a carrier frequency in a range of between about 20 khz and about 120 khz and said filter means is effective for filtering noise in the demodulated signal caused by infrared light from an electric lamp operated at a frequency between about 20 khz and about 120 khz.

26. The receiver according to claim 25, wherein said filter means is effective for filtering noise from a fluorescent lamp operated at a frequency wherein about 20 khz and about 120 khz.

27. The receiver according to claim 20, wherein the electric lamp is operated in a frequency range of between about 20 khz and about 120 khz and said infrared light transmitted by the transmitter has a carrier frequency between about 20 khz and about 120 khz.

28. The receiver according to claim 20, wherein said filter means is effective for filtering noise in the demodulated signal caused by the infrared light from a fluorescent lamp.

29. A method of transmitting and receiving information with an infrared transmission signal in the presence of an electric lamp operated at high frequency, said method comprising the steps of:

transmitting an infrared transmission signal having a carrier frequency within the frequency range of the electric lamp and modulating the transmission signal to transmit information;

receiving the infrared transmission signal and infrared light from the electric lamp;

demodulating the received signal and producing a demodulated signal including a plurality of leading and trailing edges, the transmitted information has a data element defined in the demodulated signal by a leading edge followed by a trailing edge within a predetermined time range, and the noise is present in the demodulated signal as a leading edge followed by a trailing edge at time intervals outside of the predetermined time range; and

decoding and filtering noise from the demodulated signal caused by high frequency infrared light from the electric lamp the filtering step including the step of determining which leading and trailing edges correspond to noise and which leading and trailing edges correspond to the data element, and wherein the step of decoding and filtering is performed by software within a microcontroller which controls operation of an appliance.

30. The method according to claim 29, wherein the determining step includes the steps of:

detecting the leading and trailing edges in the demodulated signal;

measuring the time interval between a detected leading edge and subsequently detected trailing edges;

comparing the measured time intervals to the predetermined time range; and

accepting the detection of a trailing edge as a decoded data element if a measured time interval is within the predetermined time range defining the data element and rejecting the detection of a trailing edge as noise if the measured time interval falls outside of the predetermined time range.

31. The method of claim 30, wherein the transmitted information includes a plurality of data elements each defined by distinct predetermined time ranges between a leading edge and a subsequent trailing edge;

and the comparing step compares the measured time intervals to each of the distinct time ranges.

32. The method of claim 31, wherein the transmitted information includes a first set of data elements and a second, inverted set of data elements in which each data element is the inverted logical equivalent of a respective data element in the first set of data elements, and the filtering step further includes the steps of:

inverting the decoded data elements of the second, inverted set of data elements; and

detecting inconsistencies between each decoded data element of the first set of data elements and the respective data element of the second set of data elements.

33. The method according to claim 31, wherein the step of filtering is performed by first detecting a leading edge and then detecting subsequent trailing edges until either one of (i) the measured time interval is within the predetermined time range of one of the data elements and (ii) the measured time interval exceeds the largest of the predetermined time ranges, at which point the filter means detects the next leading edge occurring after the last detected trailing edge.

34. A microcontroller for controlling an electric lamp including a filter in the form of software in the microcontroller and a decoding device for filtering a signal which includes a plurality of leading and trailing edges, the signal including a data element defined by a leading edge followed by a trailing edge within a predetermined time range and noise present in the signal as a leading edge followed by a trailing edge at random time intervals, wherein the filter comprises:

detecting means for detecting the leading and trailing edges in the signal;

measuring means coupled to the detecting means for measuring the time interval between a detected leading edge and subsequently detected trailing edges;

comparing means coupled to the measuring means for comparing the measured time intervals to said predetermined time range; and

means for accepting the detection of a trailing edge as the data element if a measured time interval is within the predetermined time range defining the data element and for rejecting the detection of a trailing edge as noise if the measured time interval falls outside of the predetermined time range, said means for accepting and rejecting being coupled to the comparing means.

35. The filter according to claim 34, wherein the signal includes a plurality of data elements each defined by distinct predetermined time ranges between a leading edge and a subsequent trailing edge, and said comparing means compares the measured time intervals with each of the distinct time ranges.

36. The filter according to claim 35, wherein the signal includes a first set of data elements and a second, inverted set of data elements in which each data element is the inverted logical equivalent of a respective data element in the first set of data elements, and said filter means further comprises:

means for inverting the data elements of the second, inverted set of data elements, said means for inverting being coupled to the means for accepting and rejecting; and

means for detecting inconsistencies between each data element of the first set of data elements and the respective data element of the second set of data elements, said means for detecting inconsistencies being coupled to the means for inverting.