Light generation by an electrodeless fluorescent lamp
First Claim
1. A method for producing light from an electrodeless discharge established in an ionizable medium within a sealed envelope including at least one particular ionizable gas at a given pressure capable of emitting radiant energy when subjected to a radio frequency field, the method comprising the steps of:
- coupling to the medium an electric field having a magnitude sufficient to initiate ionization of the medium to form a radiation emitting discharge; and
simultaneously coupling to the medium a radio frequency magnetic induction field for maintaining said ionization, said field having a frequency and peak magnitude such that on the average, the free electrons in the medium are accelerated to ionizing velocity in a distance equal to their mean free path in a time approximately equal to one-quarter of the period of said magnetic field, wherein both of said steps of coupling to the medium an electric field and coupling to the medium a radio frequency magnetic induction field comprise the steps of;
positioning an induction coil wrapped around a non-magnetic core in close physical proximity to said medium in said envelope; and
connecting to said induction coil a radio frequency signal.
1 Assignment
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Accused Products
Abstract
An electrodeless discharge lamp has an ionizable medium comprising a particular gas composition at a particular pressure within a sealed envelope. Radio frequency electrical power is applied to an induction coil, the magnetic induction field of which is coupled to the medium. For a particular radio frequency, the magnitude of the induction field is selected to maximize the light emitted by the discharge per watt of radio frequency power coupled thereto. The radio frequency is preferably between 3 megahertz and 300 megahertz. In one embodiment, a mixture of mercury vapor and argon is contained within an envelope having an open cylindrical cavity into which the coil fits; the portion of the interior surface of the envelope defining the cavity has a layer of an electrically insulative, ultraviolet reflective material, and the entire interior surface of the envelope has a phosphor layer; radio frequency power at a frequency of about 4 megahertz is applied to the coil by an oscillator having a tuned circuit including the inductor and the discharge.
132 Citations
28 Claims
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1. A method for producing light from an electrodeless discharge established in an ionizable medium within a sealed envelope including at least one particular ionizable gas at a given pressure capable of emitting radiant energy when subjected to a radio frequency field, the method comprising the steps of:
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coupling to the medium an electric field having a magnitude sufficient to initiate ionization of the medium to form a radiation emitting discharge; and simultaneously coupling to the medium a radio frequency magnetic induction field for maintaining said ionization, said field having a frequency and peak magnitude such that on the average, the free electrons in the medium are accelerated to ionizing velocity in a distance equal to their mean free path in a time approximately equal to one-quarter of the period of said magnetic field, wherein both of said steps of coupling to the medium an electric field and coupling to the medium a radio frequency magnetic induction field comprise the steps of; positioning an induction coil wrapped around a non-magnetic core in close physical proximity to said medium in said envelope; and connecting to said induction coil a radio frequency signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An electrodeless discharge lamp comprising:
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a sealed envelope; an ionizable medium within said envelope including at least one particular ionizable gas at a given pressure capable emitting radiant energy when subjected to a radio frequency field; and means including an induction coil wrapped around a nonmagnetic core positioned in close physical proximity to said medium in said envelope for coupling to said medium an electric field having a magnitude sufficient to initiate ionization of said medium and for simultaneously coupling to said medium in said envelope a radio frequency magnetic induction field for maintaining said ionization, the peak magnitude and frequency of said magnetic induction field being selected to optimize the efficiency of conversion of radio frequency energy coupled to said medium to emitted radiant energy. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A high frequency electrodeless fluorescent lamp comprising:
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a sealed envelope; a charge in said envelope comprising an inert starting gas and mercury vapor; a layer of fluorescent light emitting phosphor disposed on the inner surface of said envelope, said phosphor being capable of emitting white light within the visible spectrum upon absorption of ultraviolet radiation from said mercury vapor when ionized; an induction coil wrapped around a nonmagnetic core positioned so a substantial portion of its magnetic induction field passes through said charge in said envelope; means for generating electrical energy at a radio frequency above three megahertz; and means for coupling said electrical energy to said induction coil to produce thereacross an electric field that initiates ionization of said charge in said envelope to emit ultraviolet radiation and simultaneously produces a magnetic induction field for maintaining said ionization. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A high frequency electrodeless fluorescent lamp comprising:
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a sealed envelope; an ionizable medium within said envelope; an oscillator for generating high frequency electrical energy, said oscillator having a resonant circuit including a capacitor and an induction coil connected in series; and means for positioning said induction coil in close proximity to said medium in said envelope so a substantial portion of its magnetic induction field and electric field passes through said medium; the Q of said capacitor and induction coil being sufficiently large that the electric field across said induction coil initiates break down of said ionizable medium to form radiation emitting ionization and said magnetic induction field being sufficiently large to maintain the radiation emitting ionization of said medium. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification