Fluorescent light dimming
AssigneeHoneywell Inc.
InventorsLarry S. Atherton, Robert A. Black, Jr., Arlon D. Kompelien
Life of this patent
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Abstract
A dimmer for a fluorescent light in which the fluorescent light is supplied with an electrical signal having a varying magnitude, the dimmer positioning a notch of reduced signal magnitude within the electrical signal for controlling the illumination level of the fluorescent light wherein the illumination level is dependent upon the position of the notch within the varying electrical signal.
Claims25
A control arrangement for dimming a fluorescent light, said fluorescent light being supplied with an electrical signal having an electrical signal waveform of varying magnitudes and having both a positive and a negative half cycle, said control arrangement positioning a notch of reduced signal magnitude within said electrical signal waveform wherein said fluorescent light has an illumination level dependent upon the position of said notch, said arrangement comprising:
- load control means for controlling the supply of said electrical signal to said fluorescent light, said load control means comprising a first gate turn off device and a first SCR for controlling said electrical signal during said positive half cycle and a second gate turn off device and a second SCR for controlling said electrical signal during said negative half cycle, said gate turn off devices conducting during their respective half cycles prior to said notch and said first and second SCRs for conducting during their respective half cycles subsequent to said notch, neither said gate turn off devices nor said SCRs conducting during the notch in their respective half cycles, and a first parallel switch and a second parallel switch for connection in parallel to said fluorescent light, said first parallel switch being turned on during said positive half cycle and said second parallel switch being turned on during said negative half cycle;
- light level determining means for providing a light level signal having a frequency determinative of the amount of light to be emitted by said fluorescent light;
- and
- light control means responsive to said electrical signal and a counter responsive to the frequency of said light level signal for controlling said load control means to position said notch within said electrical signal waveform in accordance with said light level signal.
A control arrangement for dimming a fluorescent light, said fluorescent light being supplied with an electrical signal having an electrical signal waveform of varying magnitude and having both a positive and a negative half cycle, said electrical signal waveform having a notch of reduced signal magnitude therein, said notch having a leading edge and a trailing edge with a center between said edges, said control arrangement controlling the position of said notch by positioning said edges and said center of said notch within said electrical signal waveform wherein said fluorescent light has an illumination level dependent upon the position of said notch, said arrangement comprising:
- load control means for controlling the supply of said electrical signal to said fluorescent light, said load control means comprising a first gate turn off device and a first SCR for controlling said electrical signal during said positive half cycle and a second gate turn off device and a second SCR for controlling said electrical signal during said negative half cycle, said gate turn off devices conducting during their respective half cycles prior to said notch and said first and second SCRs for conducting during their respective half cycles subsequent to said notch, neither said gate turn off devices nor said SCRs conducting during the notch in their respective half cycles, and a first parallel switch and a second parallel switch for connection in parallel to said fluorescent light, said first parallel switch being turned on during said positive half cycle and said second parallel switch being turned on during said negative half cycle;
- light level determining means for providing a light level signal having a frequency determinative of the amount of light to be emitted by said fluorescent light;
- and
- light control means responsive to said electrical signal and a counter responsive to the frequency of said light level signal for controlling said load control means to position said notch by positioning said edges and said center within said electrical signal waveform in accordance with said light level signal.
Dependencies are inferred from the claim text.