Lamp drive circuit
First Claim
Patent Images
1. An apparatus for energizing an indicator lamp comprising:
- means for connecting one terminal of the lamp to a first electrical terminal, said first electrical terminal having an electrical potential present threat;
a main circuit for, when enabled by a first control signal, connecting a second terminal of the lamp to a second electrical terminal, said second electrical terminal having a first electrical ground reference present thereat, a difference in electrical potential between the first and second electrical terminals being sufficient to energize the lamp;
a backup circuit for, when enabled by a second control signal, connecting the second terminal of the lamp to a third electrical terminal, said third electrical terminal having a second electrical ground reference present thereat, a difference in electrical potential between the first and third electrical terminals being sufficient to energize the lamp;
sensing means for providing a signal indicative of the lamp being energized; and
control means for providing said first control signal, said second control signal, and for monitoring said signal provided by said sensing means, said control means providing said second control signal when said first control signal is provided and said signal from said sensing means indicates the lamp is not energized.
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Accused Products
Abstract
The apparatus for driving and monitoring a lamp includes a main drive circuit, a backup drive circuit, a monitoring circuit, all connected to a controller. If the controller determines that the main drive circuit cannot energize the lamp, the backup circuit is enabled to energize the lamp. For purposes of energizing the lamp, the lamp is connectable to one of two electrical ground references. If one of the ground references becomes open circuited from the remainder of the circuitry, then the lamp is energized through the other ground reference.
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Citations
33 Claims
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1. An apparatus for energizing an indicator lamp comprising:
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means for connecting one terminal of the lamp to a first electrical terminal, said first electrical terminal having an electrical potential present threat; a main circuit for, when enabled by a first control signal, connecting a second terminal of the lamp to a second electrical terminal, said second electrical terminal having a first electrical ground reference present thereat, a difference in electrical potential between the first and second electrical terminals being sufficient to energize the lamp; a backup circuit for, when enabled by a second control signal, connecting the second terminal of the lamp to a third electrical terminal, said third electrical terminal having a second electrical ground reference present thereat, a difference in electrical potential between the first and third electrical terminals being sufficient to energize the lamp; sensing means for providing a signal indicative of the lamp being energized; and control means for providing said first control signal, said second control signal, and for monitoring said signal provided by said sensing means, said control means providing said second control signal when said first control signal is provided and said signal from said sensing means indicates the lamp is not energized. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A device for energizing an indicator lamp comprising:
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a first electrical ground reference; a second electrical ground reference; means connected to one terminal of the lamp for providing electrical potential relative to said first ground reference and to said second ground reference; first actuatable switch means responsive to a first control signal for providing a connection between the other lamp terminal and the first ground reference; sensing means for providing a signal indicative of the other terminal of the lamp not being connectable to said first electrical ground reference through said first actuatable switch means; and second actuatable switch means for connecting the other terminal of the lamp to said second ground reference when said sensing means provides said signal indicative of the other terminal of the lamp not being connectable to said first ground reference.
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19. A device for energizing an indicator lamp having first and second terminals, said device comprising:
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a first ground reference; a second ground reference; means connected to the first terminal of the lamp for providing electrical potential relative to said first ground reference and to said second ground reference, said electrical potential being of sufficient value to energize the lamp; first sensing means for providing a signal indicative of the lamp being energized; a main circuit for, when enabled by a first control signal, connecting the second terminal of the lamp to said first electrical ground reference; a backup circuit for, when enabled by a second control signal, connecting the second terminal of the lamp to said second electrical ground reference; second sensing means for providing said second control signal when the second terminal of the lamp is sensed as not being connectable to said first electrical ground reference; and control means for providing said first control signal, said second control signal, and for monitoring said signal provided by first sensing means and said signal provided by second sensing means, said control means providing said second control signal when said first control signal is provided and said signal from said first sensing means indicates the lamp is not energized.
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20. An apparatus for energizing an indicator lamp comprising:
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means for connecting one terminal of the lamp to a first electrical terminal, said first electrical terminal having an electrical potential present thereat; a main drive circuit for, when enabled by a first digital control signal, connecting a second terminal of the indicator lamp to a second electrical terminal, said second electrical terminal having a first electrical ground reference present thereat, a difference in electrical potential between the first and second electrical terminals being sufficient to energize the lamp; a backup drive circuit for, when enabled by a second digital control signal, connecting the second terminal of the indicator lamp to a third electrical terminal, said third electrical terminal having a second electrical ground reference present thereat, a difference in electrical potential between the first and third electrical terminals being sufficient to energize the lamp; said first digital control signal being one digital state for enabling said main drive signal and said second digital control signal being another digital state for enabling said backup drive circuit; means for sensing when the indicator lamp is energized by the source of electrical energy; and control means for providing said first digital control signal in response to an input signal and for providing said second digital signal when said first digital control signal is provided and said sensing means indicates that the lamp is not energized. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification