Energy saving control circuit for a light switch and a method therefor

Claims

What is claimed is:

1. An energy saving control circuit for controlling the operation of an electric light, said control circuit comprising:

(A) a switch; and

(B) control means responsive to the actuation of said switch for selectively operating said light in a first timed mode in which said light is turned on for a first predetermined time period and an untimed mode in which said light is turned on for an indefinite time period, said control means:

(1) operating said light in said first timed mode when said switch is actuated in a first manner;

(2) operating said light in said untimed mode when said switch is actuated in a second manner, different than said first manner; and

(3) operating said light in said untimed mode only if said switch is first actuated in said first manner so as to initiate said first timed mode and said switch is thereafter actuated in said second manner during a predetermined time window defining a portion of said first predetermined time period.

2. The control circuit of claim 1, further including means for visually indicating that said control means is operating said light in said untimed mode.

3. The control circuit of claim 1, wherein said time window is located near the end of said first predetermined time period.

4. The control circuit of claim 3, wherein said control means generates an alert signal substantially at the beginning of said time window.

5. The control circuit of any one of claims 1, 3 or 4, wherein said first predetermined time period is approximately one hour and said time window is approximately five to ten minutes in duration.

6. The control circuit of claim 1, wherein said control means generates an alert signal a second predetermined time period before the end of said first predetermined time period to indicate that said light will be turned off at the end of said first time period if said switch is not reactuated.

7. The control circuit of any one of claims 4 or 6, wherein said alert signal is an audible alert signal.

8. The control circuit of any one of claims 4 or 6, wherein said alert signal is a visual alert signal.

9. The control circuit of claim 8, wherein said control means generates said alert signal by varying the intensity of said light.

10. The control circuit of claim 6, further including remote control means for causing said control means to reinitiate said first timed mode in response to a remote control signal generated during a time window following said alert signal.

11. The control circuit of claim 1, wherein said switch is a remote control switch.

12. The control circuit of claim 11, wherein said remote control switch is a sound activated switch.

13. The control circuit of claim 12, wherein said sound activated switch is activated by a first noise level before said light is turned on and is activated by a second noise level, lower than said first noise level, after said switch is turned on.

14. The control circuit of claim 1, wherein said second manner comprises the step of operating said switch in said first manner twice within a second predetermined time period.

15. The control circuit of claim 12, wherein said switch is a push-button switch, said first manner comprises the step of depressing said switch once and said second manner comprises the step of depressing said switch twice within said predetermined time window.

16. The control circuit of claim 1, wherein:

said switch is a push-button switch;

said first manner comprises the step of depressing said push-button switch for a period of time which is less than a second predetermined time period; and

said second manner comprises the step of depressing said push-button switch for a period of time which is greater than said second predetermined time period.

17. The control circuit of claim 1, wherein said switch is a first switch and wherein said control circuit further includes a key actuated switch, said control means operating said light in said untimed mode responsive to the actuation of said first switch in said second manner only if said key actuated switch has been actuated.

18. The control circuit of claim 1, further including a key actuated switch, said control means operating said light in said untimed mode responsive to the actuation of said key actuated switch.

19. The control circuit of claim 1, wherein said control means also operates said light in said untimed mode responsive to the receipt of a remote control signal.

20. The control circuit of claim 19, wherein said remote control signal is a radio signal.

21. The control circuit of claim 19, wherein said remote control signal is an audio signal.

22. The control circuit of claim 19, wherein said remote control signal is an ultrasonic signal.

23. The control circuit of claim 1, further including alert means for generating an alert signal after a second predetermined time period, longer than said first predetermined time period, after said control means has initiated said indefinite time period.

24. The control circuit of any one of claims 1, 3, 4, 6, 16 or 19, further including manually actuable master off switch means, said control means turning off said light responsive to the actuator of said master off switch means regardless of the mode of operation of said light at the time said master off switch is actuated.

25. The control circuit of any one of claim 1, wherein said control circuit further includes second manually operable switch means and wherein said control means operates said light in a second timed mode in which said light is turned on for a second predetermined time period which is shorter than said first predetermined time period responsive to the actuation of said second switch means.

26. The control circuit of claim 25, wherein said control means operates said light in said second timed mode responsive to the actuation of said second switch means irrespective of the mode of operation of said light when said second switch means is operated.

27. The control circuit of claim 25, wherein said first and second switch means comprise opposite ends of a rocker switch.

28. An energy saving light switch for controlling the operation of an electric light, said switch comprising:

(A) a human actuable switch;

(B) a control circuit for operating said light in a timed mode when said switch is turned on for a predetermined time period in response to the actuation of said switch, said control circuit:

(1) initiating said timed mode responsive to an initial actuation of said switch; and

(2) reinitiating said timed mode responsive to a subsequent actuation of said switch only if said subsequent actuation occurs during a predetermined time window forming a part of said predetermined time period.

29. An energy saving control circuit for controlling the operation of an electric light, said control circuit comprising:

(A) a switch; and

(B) control means responsive to the actuation of said switch means for selectively operating said light in a first timed mode in which said light is turned on for a first predetermined time period, a second timed mode in which said light is turned on for an second predetermined time period, substantially shorter than said first predetermined time period, and a third timed mode in which said light is turned on for a third predetermined time period which is substantially greater than said first predetermined time period, said control means:

(1) operating said light in said first timed mode when said switch is actuated in a first manner;

(2) operating said light in said second timed mode when said switch means is actuated in a second manner, different than said first manner;

(3) operating said light in said third timed mode when said switch means is actuated in a third manner different than said first and second manners; and

(4) operating said light in said third mode only if said switch means is first actuated in said first manner so as to initiate said first timed mode and said switch means is thereafter actuated in said second manner during a predetermined time window defining a portion of said first predetermined time period.

30. The control circuit of claim 29, further including manually actuable master off switch means, said control means turning off said light responsive to the actuation of said master off switch means regardless of the mode of operation of said light.

31. The control circuit of claim 29, wherein said time window is located near the end of said first predetermined time period.

32. The control circuit of claim 31, wherein said control means generates an alert signal at approximately the beginning of said time window.

33. The control circuit of any one of claims 29, 31, or 32, wherein said first predetermined time period is approximatly one hour and said time window is approximately five to ten minutes in duration.

34. The control circuit of claim 33, wherein said second predetermined time period is approximately ten minutes.

35. The control circuit of any one of claims 33, wherein said alert signal is an audible alert signal.

36. The control circuit of any one of claims 33, wherein said alert signal is a visual alert signal.

37. The control circuit of claim 36, wherein said control means generates an alert signal by varying the intensity of said light.

38. The control circuit of claim 29, wherein said control means generates an alert signal a fourth predetermined time period before the end of said first predetermined time period to indicate that said light will be turned off at the end of said first predetermined time period if said switch means is not reactivated.

39. The control circuit of claim 29, further including a key-actuated switch, said control means operating said light in said third timed mode responsive to the activation of said switch means in said second manner only if said key-actuated switch has been activated.

40. The control circuit of claim 29, wherein said control means also operates said light responsive to the receipt of a remote control signal.

41. The control circuit of claim 40, wherein said remote control signal is a radio signal.

42. The control circuit of claim 40, wherein said remote control signal is an audio signal.

43. The control circuit of claim 40, wherein said remote control signal is an ultrasonic signal.

44. The control circuit of claim 29, further including alert means for generating an alert signal after a fourth predetermined time period, longer than said first predetermined time period but shorter than said third predetermined time period, after said control means has initiated said third predetermined time period.

45. The control circuit of claim 29, further including means for visually indicating that said control means is operating said light in said third mode.

46. An energy saving control circuit for controlling the operation of an electric light, said control circuit comprising:

(A) a first switch;

(B) a second switch; and

(C) control means responsive to the actuation of said first and second switches for selectively operating said light in a first timed mode in which said light is turned on for a first predetermined time period, a second timed mode in which said light is turned on for a second predetermined time period, substantially shorter than said first predetermined time period, and a third timed mode in which said light is turned on for a third predetermined time period which is substantially greater than said first predetermined time period, said control means:

(1) operating said light in said first timed mode when said first switch is actuated in a first manner;

(2) operating said light in said second timed mode when said second switch is actuated; and

(3) operating said light in said third timed mode when said first switch is actuated in a second manner different that said first manner.

47. The control circuit of claim 46, wherein said second manner comprises the step of operating said first switch in said first manner twice during a fourth predetermined time period.

48. The control circuit of claim 47, wherein said first switch is a push-button switch, said first manner comprises the step of depressing said first switch once and said second manner comprises the step of depressing said first switch twice within said fourth predetermined time period.

49. The control circuit of claim 46, wherein said first switch is a push-button switch, said first manner comprises the step of depressing said push-button switch for a predetermined tube period which is less than a fourth predetermined time period and said second manner comprises the step of depressing said push-button switch for a period of time which is greater than said fourth predetermined period of time.

50. An energy saving light switch for controlling the operation of an electric light, said switch comprising:

(A) a human actuable switch;

(B) a control circuit responsive to the actuation of said human actuable switch for selectively operating said light in a first timed mode in which said light is turned on for a predetermined time period and a second untimed mode in which said light is turned on for an indefinite period of time, said control circuit:

(1) operating said light in said first timed mode responsive to an initial actuation of said human actuable switch; and

(2) operating said light in said second untimed mode responsive to an actuation of said human actuable switch during a predetermined time window forming part of said predetermined time period, said time window being located near the end of said predetermined time period.

51. The energy saving light switch on claim 50, wherein said human actuable switch is a push-button switch and wherein said control circuit operates said light in said first timed mode responsive to a single, initial actuation of said human actuable switch and wherein said control circuit operates said light in said second untimed mode responsive to a double actuation of said push-button switch during said predetermined time window.

52. The energy saving light switch of claim 50, wherein said human actuable switch is a push-button switch and wherein said control circuit operates said light in said first timed mode responsive to an initial depression of said push-button switch and operates said light in said second untimed mode responsive to the depression of said push-button switch for at least a minimum time period during said predetermined time window.

53. The energy saving light switch of claim 50, wherein said control circuit generates an alert sigal substantially at the beginning of said time window.

54. The energy saving light switch of any one of claims 50, or 53, wherein said predetermined time period is approximately one hour and said time window is approximately five to ten minutes in duration.

55. The energy saving light switch of claim 50, wherein said control circuit generates an alert signal a second predetermined time period for the end of said first predetermined time period to indicate that said light will be turned off at the end of said first time period if said switch is not reactuated.

56. The energy saving light switch of any one of claims 53 or 55, wherein said alert signal is an audible alert signal.

57. The energy saving light switch of any one of claims 53 or 55, wherein said alert signal is a visual alert signal.

58. The energy saving light switch of claim 57, wherein said control circuit generates said alert signal by varying the intensity of said light.

59. The energy saving light switch of claim 50, wherein said human actuable switch is a remote control switch.

60. The energy saving light switch of claim 59, wherein said remote control switch utilizes a radio control signal.

61. The energy saving light switch of claim 59, wherein said remote control switch utilizes an ultrasonic signal.

62. The energy saving light switch of claim 59, wherein said remote control switch utilizes an audible signal.

63. The energy saving light switch of claim 59, wherein said remote control switch is a proximity switch.

64. A method for controlling the operation of an electrical light, comprising the steps of:

(1) operating said light in a first timed mode in which said light is turned on for a predetermined time period responsive to an initial actuation of a human actuable switch; and

(2) operating said switch in a second untimed mode in which said light is turned on for an indefinite period of time responsive to the actuation of said human actuable switch during a predetermined time window forming part of said predetermined time period.

65. The method of claim 64, wherein said time window is located near the end of said predetermined time period.

66. The method of claim 65, wherein said predetermined time period is approximately one hour and said time window is approximately five to ten minutes in duration.

67. The method of claim 64, further including the step of generating an alert signal substantially at the beginning of said predetermined time window.

68. The method of claim 67, wherein said alert signal is an audible alert signal.

69. The method of claim 67, wherein said alert signal is a visual alert signal.

70. The method of claim 67, wherein said alert signal is generated by varying the intensity of said light.

71. The method of claim 64, wherein said human actuable switch is a remote control switch.

72. The method of claim 71, wherein said remote control switch utilizes a radio control signal.

73. The method of claim 71, wherein said remote control switch utilizes an ultrasonic signal.

74. The method of claim 71, wherein said remote control switch is a proximity switch.

75. The method of claim 64, wherein said human actuable switch is a push-button switch and wherein said light is operated in said first timed mode in response to a single, initial depression of said push-button switch and wherein said light is operated in said second untimed mode responsive to a double depression of said push-button switch during said predetermined time window.

76. The method of claim 64, wherein said human actuatable switch is a push-button switch and wherein said light is operated in said first timed mode responsive to an initial depression of said push-button switch and said light is operated in said untimed mode responsive to the depression of said push-button switch for at least a minimum time period during said predetermined time window.

77. A method for controlling the operation of an electric light, comprising the steps of:

(1) operating said light in a first timed mode wherein said light is turned on for a first predetermined time period responsive to the actuation of a human actuable switch in a first manner;

(2) operating said light in an untimed mode in which said light is turned on for an indefinite time period responsive to the actuation of said human actuable switch in a second manner, different than said first manner; operating said light in said untimed mode being effective only if said switch is first actuated in said first manner so as to initiate said first timed mode, said switch being thereafter actuated in said second manner during a predetermined time window defining a portion of said first predetermined time period.

78. The method of claim 77, wherein said time window is located near the end of said first predetermined time period.

79. The method of anyone of claims 77, or 78, wherein said first predetermined time period is approximately one hour and said time window is approximately five to ten minutes in duration.

80. The method of claim 78, wherein said control means generates an alert signal substantially at the beginning of said time window.

81. The method of claim 80, wherein said alert signal is an audible alert signal.

82. The method of claim 80, wherein said alert signal is a visual alert signal.

83. The method of claim 80, wherein said alert signal is generated by varying the intensity of said light.

84. A method for controlling the operation of an electric light, comprising the steps of:

(1) operating said light in a first timed mode wherein said light is turned on for a first predetermined time period when a human actuable switch is actuated in a first manner;

(2) operating said light in a second timed mode in which said light is turned on for a second predetermined time period, substantially longer than said first predetermined time period, when said switch is actuated in a second manner, different than said first manner;

(3) operating said light in an untimed mode in which said light is turned on for an indefinite time when said switch is actuated in a third manner, different than said first and second manners; operation of said light in said untimed mode being effective only if said switch is first actuated in said first or second manners so as to initiate said first or second timed modes, said switch being thereafter actuated in said third manner during a predetermined time window defining a portion of said first or second predetermined time periods.

85. The method of claim 84, wherein said time window is located near the end of said predetermined time period.

86. The method of claim 85, further including the step of generating an alert signal at approximately the beginning of said time window.

87. The method of claim 86, wherein said alert signal is an audible signal.

88. The method of claim 86, wherein said alert signal is a visual alert signal.

89. The method of claim 88, wherein said alert signal is generated by varying the intensity of said light.

90. The method of claim 84, wherein said light is operated in said second time mode responsive to the activation of said switch in said first or second manners only if a key actuated switch has first been activated.

BACKGROUND OF THE INVENTION

The present invention is directed to lighting control systems and more particularly to a system for controlling electric lights in such a manner as to minimize energy consumption.

In view both of the worsening energy shortage and of the consequent rise in energy costs, it is becoming ever more important to eliminate energy waste. One of the most common types of energy waste results from the widespread practice of neglecting to turn off electric lights when they are not needed. In particular, many people habitually enter a room, turn on a light, and then leave the room without turning the light off. It is not uncommon for a large percentage of the lights in a house or apartment, for example, to be on at one time, even if only one room is occupied and the other rooms are vacant. This problem is not limited to residential buildings, but is also frequent in commercial, industrial, health-related and other facilities.

SUMMARY OF THE INVENTION

It is the primary object of the present invention to provide a simple and economical apparatus for controlling electrical lighting in such a way as to limit the waste of electricity.

It is another object of the invention to provide such an apparatus that will nonetheless allow flexibility in its use and will not inconvenience the user.

It is still another object of the invention to provide such an apparatus that will automatically turn off lights after they have been on a preset time period, and that will give the user a warning a short time before the lights are to go out.

It is still another object of the invention to provide such an apparatus that will also allow the user to turn the lights on and keep them on indefinitely without having to reactuate them periodically.

It is yet another object of the invention to provide such an apparatus that will permit the user to actuate the lights for an indefinite period only by following a special prescribed procedure.

It is still a further object of the invention to provide such an apparatus that will nonetheless permit the user to turn the lights out instantly at any time desired.

These and other objects are achieved according to the present invention by providing an energy saving light switch comprising:

(a) a human actuable switch;

(b) a control circuit responsive to the actuation of said human actuable switch for selectively operating said light in a first timed mode in which said light is turned on for a predetermined period and a second untimed mode in which said light is turned on for an indefinite time period, said control circuit:

(1) operating said light in said first timed mode responsive to an initial actuation of said human actuable switch; and

(2) operating said light in said second untimed mode responsive to an actuation of said human actuable switch during a predetermined time window forming part of said predetermined time.

In an alternative embodiment, first and second switches are provided for turning on an electric light for first and second predetermined periods, respectively. At the end of the predetermined period for which the light has been actuated, the apparatus turns the light off automatically. One period is preferably much longer than the other, the first period being, for example, one hour and the second period being, for example, ten minutes. If one expects to be in the room for only a few minutes, one actuates the second switch, while if one expects to be there longer, one actuates the first switch. In the latter case, if one realizes after, for example, 35 minutes that one will not require the entire hour but only a few more minutes, one can then actuate the second switch, which action cancels the previous command for an hour of illumination and causes the light to remain on for only ten more minutes after the actuation of the second switch. Conversely, if one has initially actuated the second switch and then realizes that one will need to remain in the room a substantially longer time, one actuates the first switch, overriding the original command and causing the light to remain on for a full hour after the actuation of the first switch. In the preferred embodiment, a third switch, which is a master off switch, is provided to permit instant deactivation of the light at any time.

If the light is initially actuated for a period of one hour, and at the end of the hour it becomes clear that one will require illumination for a substantially longer time, one has two choices according to the preferred embodiment. At the end of the hour one can simply reactuate the first switch in the usual manner to obtain an additional hour of light. Alternatively, one can actuate the first switch in a special prescribed manner and the light will remain on indefinitely. In a preferred embodiment the first and second switches are the two sides of a momentary rocker on-off switch, and the special prescribed mode of actuation for initiating the untimed mode, in which the light will remain on indefinitely, may require depressing the first switch twice in quick succession, or depressing and holding down for a predetermined length of time, e.g. five seconds.

In one preferred embodiment, the untimed mode can be initiated only during a special interval of time, or "window", of, for example, ten minutes at the end of the hour following the actuation of the first switch. In this embodiment, an alarm is provided to alert the user that the hour is nearly over and that a decision must be made whether to allow the light to turn off at the end of the hour whether to extend the time period for a second hour, whether to extend it only for a few additional minutes by actuating the second switch, or whether to initiate the untimed mode. The alarm may be a buzzer or an electronically generated tone, or may be a flashing light. In one especially preferred embodiment, the alert signal takes the form of a dimming of the illumination provided by the light controlled by the switch of the invention. In another preferred embodiment, however, the untimed mode can be initiated at any time by following the prescribed procedure (two taps of the switch in quick succession, holding the switch down for five seconds, etc.).

In various other embodiments of the invention, the untimed mode may be initiated by other means, for example, by means of a special control key used to mechanically actuate an additional switch to initiate the untimed mode and disable the timing mechanisms used to control the switch in the timed modes. Alternatively, the untimed mode may be initiated by means of a special radio signal or a special voice signal.

In the most preferred embodiment, a second alert signal is given a predetermined time, e.g. three hours, after the initiation of the untimed mode. This alerts the user, who may have gone into another room without turning off the lights, that the lights are still on. In addition, even in the untimed mode, the lights may be turned off automatically a predetermined length of time after the generation of the second alert signal.

It is preferred to implement the present invention using integrated circuitry, but it can also be implemented using discrete circuitry or mechanical control means. It can also be carried out by means of a microprocessor.

Other objects and features of the invention will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

For the purpose of illustrating the invention, there are shown in the drawings several embodiments which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is a perspective view of one preferred embodiment of the energy-saving light switch of the invention.

FIG. 2 is a block circuit diagram showing schematically the embodiment of FIG. 1.

FIG. 3 is a circuit diagram in conjunction with which the manner in which the power supply of the switch of the invention is connected to and disconnected from line voltage will be explained.

FIG. 4 is a more detailed circuit diagram of the embodiment of FIG. 1.

FIGS. 5A and 5B show two preferred embodiments of circuitry used to control the alert signal.

FIG. 6 is a circuit diagram of control circuitry used in another preferred embodiment of the invention to initiate the untimed mode.

FIG. 6A is a circuit diagram of a dimming control circuit which can be used in connection with the circuit of FIG. 6.

FIG. 7 is a circuit diagram showing another preferred embodiment of the circuitry used to initiate the untimed mode.

FIG. 8 is a circuit diagram of the circuitry of still another preferred embodiment of the invention.

FIG. 9 is a block diagram illustrating one possible modification to the embodiment of FIG. 4.

FIG. 10 is a block diagram illustrating a modification of the embodiment of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings wherein like numerals indicate like elements, FIG. 1 shows a control switch constructed in accordance with one preferred embodiment of the present invention and designated generally as 10. Control switch 10 includes a momentary rocker on-off switch 12 provided in a wall plate 14 which is adapted to be mounted on a wall by means of screws 16 in the manner of a conventional light switch. The mechanical or electronic components by means of which the invention is carried out are contained in a housing 18 disposed on the back surface of the wall plate 14. Two wires 20 are provided for connection to the a.c. power line. Two additional wires, which are not visible in the view of FIG. 1, are connected to the wall wiring leading to the light or lights to be controlled by the switch of the invention. When the rocker switch 12 is actuated by the depression of the upper part 22 thereof, the light controlled by the switch of the invention is turned on in a first timed mode, in which the light will remain on for a relatively long time, e.g. one hour, and will then automatically be turned off unless the switch is reactivated before then to extend the period of illumination for a second hour. Actuation of the rocker switch 12 by depression of its lower part 24 actuates the light in a second timed mode for a relatively short time, e.g. ten minutes, at the end of which the light is automatically turned off unless the switch is reactuated before then. In the preferred embodiment shown, a thumb wheel 26 is provided to permit the adjustment of the length of time the light remains on in the first timed mode.

Shortly before the end of the hour for which the light is lit in the first timed mode, an alert signal is produced to alert anyone in the room that only a short time, e.g. five minutes or ten minutes, remains before the light will be automatically extinguished. The alert signal may be a tone produced by a buzzer or an electronic tone generator via a speaker 28 provided in the face of the wall plate 14. Alternatively, the alert signal may be generated by causing the light being controlled (light 38) to blink on and off. In one preferred embodiment, the upper part 22 of the rocker switch 12 can be reactuated at any time to cause the light to remain illuminated for an hour after such reactuation. In this way, once the alert signal has sounded, or at any other time, one can reactuate the upper part 22 of the switch 12 to obtain an additional hour of illumination. Similarly, the lower part 24 of switch 12 can be actuated at any time. If this is done, the light will remain lit for ten minutes after such actuation, even if the upper part 22 of the switch 12 has been actuated in the preceding hour. If the light switch of the invention is installed in a room adjacent a hallway or other room that is poorly illuminated, then when one is ready to leave the well-lit room having the light switch of the invention and to pass through the unlit corridor, one can actuate the lower part 24 of the switch 12, causing the light to remain on a sufficient length of time to permit one to leave the room and pass through the corridor with the aid of the light. The light will then automatically be turned off ten minutes later. The preferred embodiment shown also has a master off switch 30 by means of which the light can be turned off instantly at any time.

There will inevitably be occasions when a user must remain for several hours in a room provided with the light switch 10 of the invention. In such a case, it is desirable not to have to reactuate the light periodically, and it is also desirable not to be interrupted every hour by the alert signal. The switch 10 of the invention is, therefore, provided with an untimed mode of operation, in which the light controlled by the switch 10 remains on indefinitely, as with conventional switches. It would, of course, be possible simly to provide a second rocker switch to perform like a conventional light switch while the other rocker switch is used to turn the light on in either of the two timed modes. If this were done, however, the temptation would be great always to use the conventional switch. Therefore, although an embodiment having an additional switch to initiate the untimed mode falls within the scope of the invention, it is greatly preferred instead that the untimed mode should be initiated only by means of actuating rocker switch 12 in a special prescribed manner, such as actuating the upper part 22 of the switch 12 twice in quick succession, or depressing the upper part 22 and holding it down for a certain minimum time interval such as five seconds.

This arrangement, however, is also liable to abuse, since a person who habitually fails to turn the light off when leaving the room can easily adapt to the necessity of tapping the light switch twice rather than once, or holding it down for at least five seconds, thus subverting the purpose of the invention. To prevent this, it is preferred that operating switch 12 in the special prescribed fashion will initiate the untimed mode only when the switch 10 is previously put in the first timed mode and the light has then been allowed to burn for a set amount of time, e.g. 55 minutes, without the switch 10 of the invention having been reactuated or turned off in the meantime. In this embodiment, the user actuates the switch 10 in the long (first) timed mode by depressing the upper part 22 of the rocker switch 12. After 55 minutes have elapsed, the switch 10 produces the alert signal to indicate the approaching end of the one hour of illumination provided by the long timed mode. Simultaneously with the generation of the alert signal, a five-minute "window" begins during which the user can initiate the untimed mode by actuating the rocker switch 12 in the special prescribed fashion. The untimed mode cannot be initiated until the lights have been on 55 minutes in the first timed mode. Thus, with this embodiment, it is impossible to waste more than an hour's worth of electricity at once without following the prescribed pattern.

The likelihood of waste can be further reduced by means of another variation of the embodiment described above. In the embodiment described thus far, each normal actuation of the rocker switch 12 cancels previous commands, so that if a person actuates the upper part 22 of the switch 12 and then several minutes later actuates upper part 22 a second time, the second actuation resets the timing mechanism of the switch 10 so that the light will stay on for an hour from the second actuation. If the switch 12 is thoughtlessly touched by someone after the light has already been turned on, it is possible that the light will unnecessarily remain on for an hour from the last actuation of switch 12 rather than from the first actuation thereof. To prevent this possibility, it may be desirable to disable the upper part 22 of the rocker switch 12 from the time it is first actuated until the generation of the alarm signal 55 minutes later. With this feature, the one hour timed mode cannot be accidentally reinitiated during the 55 minute time interval. If, however, the user wishes to reinitiate a one hour timed interval, he may do so after the alarm signal is given. The light can also be turned off instantly at any time by means of the master off switch 30, and the short timed mode can be initiated at any time by depressing the lower part 24 of switch 12, even if the upper part 22 of the switch 12 has previously been actuated.

Instead of or in addition to permitting the untimed mode to be initiated only during a brief "window" after the light has been operated in the long timed mode for almost a full hour, a lock 32 can be provided that must be turned by means of a special control key in order to permit initiation of the untimed mode. The lock 32 can, for example, comprise a key-operated switch that connects and disconnects circuitry by means of which the untimed mode is initiated, as will be described below.

In the preferred embodiment, a light emitting diode (LED) 34 is provided to indicate whether the switch 10 is operating in a timed mode or in the untimed mode. It is preferred that the LED 34 is lit when the switch is operating in a timed mode, but the reverse arrangement is also contemplated. In the latter case, it is especially advantageous for the LED 34 to flash, so as to attract the attention of anyone in the room who passes the switch 10.

In another preferred embodiment, the third mode of operation, referred to above as "the untimed mode", may be replaced with what is really a third timed mode, initiated in any of the same ways as those described above for the untimed mode. In the third timed mode, an alert signal is generated after a relatively long period of time, such as three hours, and if the switch 10 is not reactuated within a short time (for example, ten minutes) of the alert signal being given, the light is automatically turned off.

As stated above, the present invention can be carried out by mechanical means or by electronic means, including a microprocessor. It is preferred, however, to use electronic circuitry. FIG. 2 is a block diagram showing one possible electric circuit used to carry out the invention. In this embodiment, switches Sw1, Sw2 and Sw3 correspond respectively to the up