Dimmable ballast for an electrodeless discharge lamp
First Claim
1. A ballast for an electrodeless discharge lamp, said ballast comprising:
- an induction coil adapted in use to be disposed adjacent to said discharge lamp;
a high frequency power supply supplying a high frequency electric power to said induction coil for operating said lamp; and
a dimmer controller which, in response to a dimmer command designating a varying dimming ratio, generates a control signal defining a first period in which said power supply is controlled to apply a coil voltage of a first level to said induction coil for operating said lamp, said first period being followed by a second period in which said power supply is controlled to apply the coil voltage of a second level that is lower than said first level and fails to sustain the lamp,wherein said dimmer controller generates said control signal that defines, between said second period and said first period, a starting period in which said coil voltage increases continuously.
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Accused Products
Abstract
A ballast for an electrodeless discharge lamp includes a high frequency power supply that supplies a high frequency electric power to an induction coil for operating the lamp. A dimmer controller generates a control signal in response to a dimmer command designating a varying dimming ratio. The control signal defines a first period Ton in which the power supply is controlled to apply a coil voltage of a first level V1 to the induction coil for operating the lamp. The first period is followed by a second period Toff in which the power supply is controlled to apply the coil voltage of a second level V2 that is lower than the first level and fails to sustain the lamp. The control signal defines, between the second period and the first period, a starting period Tst in which the coil voltage increases continuously for smooth transition from an off-condition to an on-condition of the lamp.
21 Citations
17 Claims
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1. A ballast for an electrodeless discharge lamp, said ballast comprising:
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an induction coil adapted in use to be disposed adjacent to said discharge lamp; a high frequency power supply supplying a high frequency electric power to said induction coil for operating said lamp; and a dimmer controller which, in response to a dimmer command designating a varying dimming ratio, generates a control signal defining a first period in which said power supply is controlled to apply a coil voltage of a first level to said induction coil for operating said lamp, said first period being followed by a second period in which said power supply is controlled to apply the coil voltage of a second level that is lower than said first level and fails to sustain the lamp, wherein said dimmer controller generates said control signal that defines, between said second period and said first period, a starting period in which said coil voltage increases continuously. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification