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Researchers Submit Patent Application, "Rf Coupler Stabilization in an Induction Rf Fluorescent Light Bulb", for Approval

June 18, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Godyak, Valery A. (Brookline, MA); Maya, Jakob (Brookline, MA), filed on July 19, 2013, was made available online on June 5, 2014.

The patent's assignee is Lucidity Lights, Inc.

News editors obtained the following quote from the background information supplied by the inventors: "The present invention generally relates to induction lamps, and more specifically to increasing RF coupler positional stabilization in an induction lamp.

"Discharge lamps create light by exciting an electrical discharge in a gas and using that discharge to create visible light in various ways. In the case of fluorescent lamps the gas is typically a mixture of argon, krypton and/or neon, plus a small amount of mercury. Other types of discharge lamps may use other gasses. The gas is contained in a partially evacuated envelope, typically transparent or translucent, typically called a bulb or arc tube depending upon the type of lamp.

"In conventional lamps electrically conductive electrodes mounted inside the bulb or arc tube along with the gas provide the electric field used to drive the discharge.

"Use of electrodes creates certain problems. First, the discharge is typically designed to have a relatively high voltage in order to minimize loses at the electrodes. In the case of fluorescent lamps, this may lead to long, thin lamps, which function well for lighting office ceilings, but are not always a good fit for replacing conventional incandescent lamps. Fluorescent lamps designed to replace incandescent lamps, known as compact fluorescent lamps, or CFLs, are typically constructed by bending the long, thin tube, such as into multiple parallel tubes or into a spiral, which is now the most common form of CFLs. A plastic cover shaped like a conventional incandescent lamp is sometimes placed over the bent tubes to provide a more attractive shape, but these covers absorb light, making the lamp less efficient. Bent and spiral tube lamps also have wasted space between the tubes, making them larger than necessary. The use of a cover increases the size further.

"The use of electrodes creates problems other than shape and size. Electrodes can wear out if the lamp is turned on and off many times, as is typical in a residential bathroom and many other applications. The life of the electrodes can also be reduced if the lamp is dimmed, because the electrodes are preferably operated in a specific temperature range and operation at different power levels can cause operation outside the preferred ranges, such as when operating at lower power, which can allow the electrodes to cool below the specified temperature range.

"In addition, the long thin shape selected, because it is adapted to allow use of electrodes, tends to require time for mercury vapor to diffuse from one part of the tube to another, leading to the long warm-up times typically associated with many compact fluorescent lamps.

"Finally, the electrodes are normally designed to be chemically compatible with the gas used in the lamp. While this is not usually a concern with typical fluorescent lamps, it can be a problem with other types of discharge lamps.

"One way to avoid the problems caused by electrodes is to make a lamp that does not use electrodes, a so-called electrodeless lamp. In an electrodeless lamp, the discharge may be driven by, for example, 1) an electric field created by electrodes mounted outside the bulb or arc tube; 2) an electric field created by a very high frequency electromagnetic field, usually in combination with a resonant cavity, or 3) an electric field created by a high frequency magnetic field without the use of a resonant cavity. This latter lamp is called an induction-coupled electrodeless lamp, or just 'induction lamp.'

"In an induction lamp, a high frequency magnetic field is typically used to create the electric field in the lamp, eliminating the need for electrodes. This electric field then powers the discharge.

"Since induction lamps do not require use of electrodes, they do not need to be built into long thin tubes. In fact, a ball-shaped bulb, such as the bulb used for conventional incandescent lamps, is a preferred shape for an induction lamp. In addition, since induction lamps do not use electrodes, they can be turned on and off frequently without substantial adverse impact on loss of life. The absence of electrodes also means that induction lamps can be dimmed without reducing lamp life. Finally, the ball-shaped lamp envelope allows rapid diffusion of mercury vapor from one part of the lamp to another. This means that the warm-up time of induction lamps is faster than the warm-up time of most conventional compact fluorescent lamps.

"Induction lamps fall into two general categories, those that use a 'closed' magnetic core, usually in the shape of a torus, and those that use an 'open' magnetic core, usually in the shape of a rod. Air core induction lamps fall into this latter category. Closed core lamps can be operated at frequencies generally above 50 kHz, while open core lamps require operating frequencies of 1 MHz and above for efficient operation. The lower operating frequency of closed core induction lamps makes them attractive; however, the bulb design required to accommodate the closed core makes them generally unsuitable for replacing standard in incandescent lamps. Open core induction lamps, while requiring higher operating frequencies, allow the design of lamps that have the same shape and size as common household incandescent lamps. This application is addressed to open core induction lamps.

"In spite of their obvious advantages, there are very few open core induction lamps on the market today. One reason for the lack of commercially successful products is the cost of the high frequency ballast. Conventional fluorescent lamps, including CFLs, can be operated at frequencies from 25 kHz to 100 kHz, a frequency range where low cost ballast technology was developed in the 1990s'; and closed core induction lamps can be operated at frequencies from 50 kHz to 250 kHz, for which the ballasts are only slightly more expensive. However, open core induction lamps require operating frequencies of 1 MHz or higher. The United States Federal Communications Commission (FCC) has established a 'lamp band' between 2.51 MHz and 3.0 MHz that has relaxed limits on the emission of radio frequency energy that may interfere with radio communication services. Cost effective open core induction lamps should therefore have an operating frequency of at least 2.51 MHz.

"The lack of commercially successful open core induction lamps can be traced to the failure to develop a low cost ballast that can operate in the 2.51 MHz to 3.0 MHz band while meeting all the requirements of the FCC, is small enough to fit into a lamp and ballast housing that has the same size and shape as a conventional incandescent lamp, and can be dimmed on conventional TRIAC dimmers found in homes in the U.S. The present disclosure addresses one or more of these issues. Therefore a need exists for improved induction lamps, especially in residential applications."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "In accordance with exemplary and non-limiting embodiments, systems and methods for the configuration and operation of an electrodeless fluorescent lamp are provided.

"The present disclosure depicts an induction lamp with structures that increase RF coupler positional stabilization. These structures are capable of providing increased structural support and axial alignment for a power coupler located in a re-entrant cavity of a lamp envelope of the induction RF fluorescent light lamp, the re-entrant cavity having an open entrance end and a closed innermost end, and a pliable spacer positioned between and in contact with both the innermost end of the power coupler and the innermost end of the re-entrant cavity, the pliable spacer having a shape that both provides structural support to prevent movement of the power coupler axially with respect to the re-entrant cavity and to provide axial alignment of the power coupler to the re-entrant cavity. The pliable spacer also provides a buffer between the power coupler and the innermost end of the re-entrant cavity, reducing rattle and the potential for damage to the innermost end of re-entrant cavity by the power coupler. In embodiments, the structure(s) may be one component or a number of components acting together to provide alignment support.

"In embodiments, the induction RF fluorescent lamp may comprise an envelope with a re-entrant cavity both covered on a partial vacuum side with phosphor and filled with a working gas mixture, the re-entrant cavity having an open entrance end and a closed innermost end; a power coupler located inside the re-entrant cavity, the power coupler comprising a core overwound with at least one turn of an electrical conductor and having an innermost end proximate to the innermost end of the re-entrant cavity; and a pliable spacer positioned between and in contact with both the innermost end of the power coupler and the innermost end of the re-entrant cavity, the pliable spacer having a shape that both provides structural support to prevent movement of the power coupler axially with respect to the re-entrant cavity and to provide axial alignment of the power coupler to the re-entrant cavity. In embodiments, the core of the power coupler may be a ferromagnetic core; a non-magnetic, non-conductive core; and the like. The shape of the pliable spacer may be a conical frustum, the conical frustum having two parallel surfaces of unequal surface area, where the smaller of the two parallel surfaces faces the closed innermost end of the re-entrant cavity. The shape of the pliable spacer may be at least partly hemispherical, the rounded side of the hemispherical pliable spacer facing the innermost end of the re-entrant cavity. The shape of the pliable spacer may be a cylinder. A second spacer may be located proximate to the entrance end of the re-entrant cavity, where the second spacer is positioned between the power coupler and the re-entrant cavity, the second spacer providing additional structural support to prevent movement of the power coupler with respect to the re-entrant cavity and axial alignment of the power coupler to the re-entrant cavity. The pliable spacer may be made of electrically non-conductive material having a temperature rating of at least 200.degree. C., such as a fiber-reinforced polymeric material, a ceramic fiber material, fiberglass, plastic, silicon rubber, and the like. The pliable spacer may have a hole in the center having the diameter greater than the diameter of the core of the power coupler. The pliable spacer may have a lip facing the innermost end of the power coupler so as to mechanically secure the position of the power coupler with respect to the re-entrant cavity.

"In embodiments, the induction RF fluorescent lamp may comprise an envelope with a re-entrant cavity both covered on a partial vacuum side with phosphor and filled with a working gas mixture, the re-entrant cavity having an open entrance end and a closed innermost end; a power coupler located inside the re-entrant cavity, the power coupler comprising a core overwound with at least one turn of an electrical conductor and having an innermost end proximate to the innermost end of the re-entrant cavity; a rigid spacer positioned in contact with the innermost end of the power coupler; a pliable spacer positioned between and in contact with both the rigid spacer and the closed innermost end of the re-entrant cavity, the combination of the rigid spacer and the pliable spacer providing structural support to prevent axial movement of the power coupler with respect to the re-entrant cavity and to provide axial alignment of the power coupler to the re-entrant cavity. In embodiments, the rigid spacer and the pliable spacer may be made of different materials. The pliable spacer may be made of a fiber-reinforced polymer and the rigid spacer made of a high temperature plastic. The rigid spacer and the pliable spacer may be combined as a single piece, such as the single piece being a conical frustum shape, the conical frustum shape having two parallel surfaces of unequal surface area, where the smaller of the two parallel surfaces is in contact with the closed innermost end of the re-entrant cavity, and the larger of the two parallel surfaces is in contact with the innermost end of the power coupler. The single piece may be made of a fiber-reinforced polymer, ceramic fiber material, fiberglass, plastic, and the like.

"These and other systems, methods, objects, features, and advantages of the present invention will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings. All documents mentioned herein are hereby incorporated in their entirety by reference.

BRIEF DESCRIPTION OF THE FIGURES

"The invention and the following detailed description of certain embodiments thereof may be understood by reference to the following figures:

"FIG. 1 depicts a high-level functional block diagram of an embodiment of the induction lamp.

"FIG. 2 shows a typical circuit diagram of a TRIAC based dimmer known in the art.

"FIG. 3 shows a block diagram of an electronic ballast without an electrolytic smoothing capacitor known in the art.

"FIG. 4 illustrates dimming operation of the electronic ballast known in the art.

"FIG. 5 shows a block diagram of an electronic ballast with a dimming arrangement in accordance with the present invention.

"FIG. 6 illustrates the ballast and lamp operation method in accordance with an exemplary embodiment.

"FIG. 7 shows a block-schematic diagram of the TRIAC dimmed ballast according to an exemplary embodiment.

"FIG. 8 shows a block-circuit diagram according to an exemplary embodiment.

"FIG. 9 shows oscillograms of the TRIAC voltage, lamp current and lamp voltage in a dimming mode, according to an exemplary embodiment.

"FIG. 10 shows an embodiment for a pass-through circuit.

"FIG. 11 depicts an exemplary embodiment cross-section view of an RF induction lamp.

"FIG. 12 depicts an exemplary embodiment cross-section view of a coupler with the inserted grounded shell.

"FIG. 12A depicts an exemplary embodiment of a capacitor acting to provide electrical isolation from a ferrite core coupler.

"FIG. 12B depicts an exemplary embodiment of a capacitor acting to provide electrical isolation from an air-core coupler

"FIG. 13 shows an exemplary experimental and commercial lamp covered with copper foil for purposes of an experiment.

"FIG. 14 illustrates an exemplary experimental set-up for measurement of the lamp surface voltage.

"FIG. 15 provides experimental data of conductive EMI (points) and the allowed limits (lines) taken with a related art lamp using a LISN set up.

"FIG. 16 provides experimental data of conductive EMI (points) and the allowed limits (lines) taken with the test lamp accordance to an exemplary and non-limiting embodiment.

"FIG. 17 shows a block-circuit diagram of electronic ballast comprising a Passive Valley Fill PF correction circuit accordingly to the present invention.

"FIG. 18 shows waveforms of the input current and DC bus voltage of the ballast in FIG. 17.

"FIG. 19 shows a block-circuit diagram of electronic ballast with a Passive Valley Fill Circuit dimmed by TRIAC based dimmer.

"FIG. 20 shows waveforms of the input current and DC bus voltage of the ballast in FIG. 19.

"While described in connection with certain exemplary and non-limiting embodiments, other exemplary embodiments would be understood by one of ordinary skill in the art and are encompassed herein. It is therefore understood that, as used herein, all references to an 'embodiment' or 'embodiments' refer to an exemplary and non-limiting embodiment or embodiments, respectively."

For additional information on this patent application, see: Godyak, Valery A.; Maya, Jakob. Rf Coupler Stabilization in an Induction Rf Fluorescent Light Bulb. Filed July 19, 2013 and posted June 5, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4562&p=92&f=G&l=50&d=PG01&S1=20140529.PD.&OS=PD/20140529&RS=PD/20140529

Keywords for this news article include: Light Bulb, Electronics, Lucidity Lights Inc, Government Agencies Offices and Entities.

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Source: Electronics Newsweekly


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