Apparatus and method for compensating for reduced light output of a light source having a lumen depreciation characteristic over its operational life

• US 20050184681A1
• Filed: 02/24/2004
• Published: 08/25/2005
• Est. Priority Date: 02/24/2004
• Status: Active Grant

• Current Assignee: Musco Corporation
• Original Assignee: Musco Corporation
• Inventors: Gordin, Myron K., Boyle, Timothy J.
• Granted Patent: US 7,176,635 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: F21V 23/026 Fastening of transformers or ballasts
• CPC Class Codes: F21W 2131/10 Outdoor lighting
• CPC Class Codes: F21W 2131/105 of arenas or the like
• CPC Class Codes: H05B 41/392 using semiconductor devices, e.g. thyristor
• CPC Class Codes: H05B 41/40 discontinuously

Abstract

A method, apparatus, and system for compensating for lamp lumen depreciation. The method includes operating the lamp under rated wattage for a period towards the first part of operating life of the lamp. Operating wattage is increased at one or more later times. Energy savings are realized. The increases also restore at least some light lost by lamp lumen depreciation. The apparatus uses a timer to track operating time of the lamp. A few wattage changes made at spaced apart times can be made in a number of ways, including changing capacitance to the lamp, or using different taps on the lamp ballast.

Claims

1. A method of operating a light source having a rated operating wattage (ROW) and a lumen depreciation characteristic comprising:

a. operating the light source at a first operating wattage for a first time period of operation;

b. after the end of the first time period, operating the light source at a second actual operating wattage greater than said first operating wattage.

2. The method of claim 1 wherein the light source is an HID lamp.

3. The method of claim 2 wherein the HID lamp is a metal halide lamp.

4. The method of claim 2 wherein the HID lamp is a sodium or low pressure sodium lamp.

5. The method of claim 4 wherein the HID lamp is a mercury vapor lamp.

6. The method of claim 1 wherein the light source is a fluorescent lamp.

7. The method of claim 1 wherein said first actual operating wattage is correlated to a desired light output from the light source.

8. The method of claim 7 wherein the desired light output is correlated to a specified light level at a target area.

9. The method of claim 8 wherein the specified light level is related to a designed lighting system for a target area.

10. The method of claim 1 wherein the first operating wattage is lower than ROW for the lamp.

11. The method of claim 7 wherein the first actual operating wattage is selected to be less than ROW but produces approximately desired output for the light source.

12. The method of claim 10 wherein the first actual operating wattage is in a range of approximately 2% to 30% less than ROW.

13. The method of claim 1 wherein the first time period is correlated to the lumen depreciation characteristic of the light source.

14. The method of claim 1 wherein the first time period approximates an initial rapid lumen depreciation for the light source.

15. The method of claim 14 wherein the first time period is in the range of approximately 100 to 300 hours.

16. The method of claim 1 wherein the first time period of operation is after an initial time of operation of the lamp.

17. The method of claim 16 wherein the lamp is run at ROW for an initial time of operation, followed by operation at the first operating wattage for the first time period, followed by operation at the second operating wattage for the second time period.

18. The method of claim 17 wherein the initial time of operation is approximately 100 hours of cumulative operating time of the lamp, the first time period is approximately 700 hours thereafter, and the second time period is greater than 700 hours thereafter.

19. The method of claim 1 wherein second actual operating wattage is correlated to amount of additional watts to compensate for lumen depreciation at that point in operating life of the light source, and increase light output of the light source back to approximately the desired light output.

20. The method of claim 17 wherein the second actual operating wattage is less than operating wattage rating for the light source.

21. The method of claim 1 further comprising

c. operating the light source at the second actual operating wattage below the normal operating wattage rating for a second time period of operation.

22. The method of claim 21 wherein the second time period is correlated to the lumen depreciation characteristic of the light source.

23. The method of claim 22 wherein the second time period is longer than the first time period.

24. The method of claim 23 wherein the second time period is substantially longer than the first time period.

25. The method of claim 24 wherein the second time period is on the order of 1000 hours.

26. The method of claim 21 further comprising

d. operating the light source at the third actual operating wattage below the normal operating wattage rating for a third time period of operation.

27. The method of claim 21 further comprising

e. operating the light source at the third actual operating wattage at or near the normal operating wattage rating for a third period of operation.

28. The method of claim 21 further comprising

e. operating the light source at the third actual operating wattage above the normal operating wattage rating for a third time period of operation.

29. The method of claim 1 wherein the actual operating wattage is adjusted automatically based on keeping track of cumulative operating time of the light source.

30. The method of claim 1 wherein the actual operating wattage is adjusted by altering capacitance in line with the to the light source.

31. A method of operating a light source having a lumen depreciation characteristic comprising:

a. specifying a desired light output from the light source;

b. reducing actual operating wattage below rated operating wattage during an initial period of operation but maintaining approximate desired level output;

c. at several spaced apart times, increasing actual operating wattage an amount to restore light output to desired light output to compensate for lumen depreciation

d. so that desired light output is reasonably consistent, but energy consumption is reduced, through the operating life of the light source.

32. The method of claim 31 wherein the number of increases of actual operating wattage are minimized, by having an increase relatively early in operating life, and having any subsequent increase delayed a substantially longer time.

33. The method of claim 31 wherein increases in wattage are delayed until light output has diminished substantially from desired output.

34. The method of claim 31 wherein the light source is selected such that its initial light output exceeds desired light output if operated at rated wattage.

35. The method of claim 31 wherein the light source is an HID lamp.

36. The method of claim 31 wherein the spaced apart times are programmed into a timing device.

37. The method of claim 36 wherein the timing device monitors cumulative operation time for the light source.

38. A method of operating a light source having a lumen depreciation characteristic, the light source adapted to provide a level of illumination to a target area, comprising:

(a) specifying a desired illumination level for the target area;

(b) operating the light source at an initial operating wattage to provide an initial illumination that at least meets the desired illumination level;

(c) monitoring actual illumination level at the target area;

(d) increasing operating wattage to the lamp when the actual illumination level at the target area drops below a threshold.

39. The method of claim 38 wherein the initial illumination level exceeds the desired illumination level and the threshold is at or near the desired illumination level.

40. The method of claim 38 wherein the initial illumination level exceeds the desired illumination level and the threshold is below the desired illumination level.

41. The method of claim 38 wherein the initial illumination level is at or near the desired illumination level, and the threshold is below the desired illumination level.

42. An apparatus for compensating for a lumen depreciation characteristic comprising:

a. a light source producing an initial lumen output at a recommended operating wattage and having a lumen depreciation characteristic;

b. a ballast operatively connectable to the light source through which electrical energy is supplied for operation of the light source;

c. a switch adapted to provide a plurality of electrical paths relative the light source or ballast, each electrical path effecting a different operating wattage to the light source;

d. a timer which monitors cumulative operating time of the light source and

e. an actuator adapted to operate the switch at pre-selected times in cumulative operating time monitored by the timer.

43. The apparatus of claim 42 wherein the light source is an HID lamp.

44. The apparatus of claim 43 wherein the HID lamp is a metal halide lamp.

45. The apparatus of claim 42 wherein the light source is a fluorescent lamp.

46. The apparatus of claim 42 wherein a first actual operating wattage is correlated to a desired light output from the light source.

47. The apparatus of claim 46 wherein the desired light output is correlated to a specified light level at a target area.

48. The apparatus of claim 47 wherein the specified light level is related to a designed lighting system for a target area.

49. The apparatus of claim 48 wherein the desired light output is less than initial normal light output of the light source when operated at normal operating wattage rating.

50. The apparatus of claim 48 wherein the first actual operating wattage is selected to be less than rated wattage but produce approximately desired output for the light source or slightly higher.

51. The apparatus of claim 50 wherein the first actual operating wattage is in a range of 2% to 30% below ROW.

52. The apparatus of claim 42 wherein the first time period is after an initial period of cumulative operation of the light source.

53. The apparatus of claim 52 wherein the initial period of cumulative operation is approximately 100 hours, the first time period is approximately 100 hours to 700 hours, and the second time period begins at approximately 700 hours.

54. The apparatus of claim 50 wherein the first time period is correlated to the lumen depreciation characteristic of the light source.

55. The apparatus of claim 54 wherein the first time period approximates an initial rapid lumen depreciation for the light source.

56. The apparatus of claim 55 wherein the first time period is in the range of approximately 100 to 300 hours.

57. The apparatus of claim 50 wherein the first time period is at approximately 1000 hours of cumulative operating time.

58. The apparatus of claim 42 wherein second actual operating wattage is correlated to amount of additional watts to compensate for lumen depreciation at that point in operating life of the light source, and increase light output of the light source back to approximately the desired light output.

59. The apparatus of claim 58 wherein the second actual operating wattage is less than operating wattage rating for the light source.

60. The apparatus of claim 59 further comprising

f. operating the light source at the second actual operating wattage below the normal operating wattage rating for a second time period of operation.

61. The apparatus of claim 60 wherein the second time period is correlated to the lumen depreciation characteristic of the light source.

62. The apparatus of claim 61 wherein the second time period is longer than the first time period.

63. The apparatus of claim 62 wherein the second time period is substantially longer than the first time period.

64. The apparatus of claim 63 wherein the second time period is on the order of 1000 hours.

65. An apparatus for supplying operating wattage to a lamp comprising:

a. An ED lamp of a rated operating wattage;

b. a connection to the lamp, a connection to source current, and a switching means to select between a plurality of operating wattages including a first operating wattage below said rated operating wattage of said lamp, and at least one operating wattage greater than the first operating wattage but less than the rated operating wattage of said lamp;

c. a timer adapted to measure accumulated time of operation of said lamp;

d. means adapted to be actuated by the timer to actuate the switching means at preselected accumulated times.

66. The apparatus of claim 65 wherein the change is change according to lumen depreciation characteristic of the lamp.

67. The apparatus of claim 66 wherein the characteristic includes a first rapid depreciation period and a subsequent slower depreciation period.

68. The apparatus of claim 65 wherein the first period is shorter in duration than subsequent periods.

69. An apparatus comprising:

a. a light fixture comprising;

i. a lamp having a lumen depreciation characteristic and an initial light output at rated operating wattage;

ii. a reflector in which the lamp is positioned;

iii. a mount for the lamp and reflector to a support structure;

iv. a ballast for providing electrical energy to the lamp to produce its light output;

b. a timer to monitor cumulative operation time of a lamp;

c. a circuit for providing a plurality of operating wattages to the lamp;

d. a switch for selecting from the plurality of operating wattages in the circuit;

e. an actuator to actuate the switch based on one or more times from the timer.

70. A system comprising:

a. a plurality of light fixtures;

b. each light fixture comprising;

i. a lamp having a lumen depreciation characteristic and an initial light output at rated operating wattage;

ii. a reflector in which the lamp is positioned;

iii. a mount for the lamp and reflector to a support structure;

iv. a ballast for providing electrical energy to the lamp to produce its light output;

c. a timer to monitor cumulative operation time of a lamp;

d. a circuit for providing a plurality of operating wattages to the lamp;

e. a switch for selecting from the plurality of operating wattages in the circuit;

f. an actuator to actuate the switch based on one or more times from the timer.

71. A method for cost and energy savings for lighting applications using one or more lamps having an LLD characteristic, comprising:

a. operating the lamp under ROW for a given time period during its operating life;

b. increasing operating wattage towards ROW at a time thereafter before end of normal operating life of the lamp.

72. The method of claim 71 wherein the step of operation of the lamp under ROW is at no greater than approximately 30% under ROW.

73. The method of claim 71 wherein the increase in operating wattage is related to compensation for lumen depreciation.

74. The method of claim 71 further comprising increasing operating wattage to at or near ROW before end of normal operating life of the lamp.

75. The method of claim 71 further comprising designing a lighting system comprising a plurality of lamps and fixtures to light a target area, whereby the number of lamps and fixtures to provide reasonably illumination levels to the target area over at least a substantial part of the normal operating life of the lamps is reduced by applying the method of claim 71 to said lamps, for both capital and energy cost savings for installation, operation, and maintenance of the fixtures over time.