Apparatus and method for compensating for reduced light output of a solid-state light source having a lumen depreciation characteristic over its operational life
First Claim
1. A method of operating at least one solid state light source having an envelope of operation for drive current and a lumen depreciation characteristic comprising:
- operating the at least one solid state light source at a first drive current for a first time period of operation wherein the first drive current is within the envelope of operation;
b. after the end of the first time period, operating the at least one solid state light source at a second drive current greater than said first drive current, wherein the second drive current is within the envelope of operation.
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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. In one aspect the invention pertains to solid state sources. The invention can pertain to a variety of applications including wide area lighting, indoor lighting, pathway lighting, parking lot lighting, street lighting, under-counter or -cabinet lighting, and others.
96 Citations
9 Claims
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1. A method of operating at least one solid state light source having an envelope of operation for drive current and a lumen depreciation characteristic comprising:
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operating the at least one solid state light source at a first drive current for a first time period of operation wherein the first drive current is within the envelope of operation; b. after the end of the first time period, operating the at least one solid state light source at a second drive current greater than said first drive current, wherein the second drive current is within the envelope of operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for compensating for a lamp lumen depreciation characteristic comprising:
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a. at least one solid state light source producing, an initial lumen output at a drive current within a recommended envelope of operation and having a lumen depreciation characteristic; a current driver operatively connectable to the at least one solid state 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 current driver, each electrical path effecting a different drive current to the at least one solid state light source; d. a timer which monitors cumulative operating time of the at least one solid state light source; and e. an actuator adapted to operate the switch at pre selected times in cumulative operating, time monitored by the timer.
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Specification