Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Reexamination Certificate
2002-04-26
2004-07-27
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
C313S485000, C313S318010, C313S318050, C313S318100
Reexamination Certificate
active
06768254
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electrodeless discharge lamp, in particular, a self-ballasted electrodeless discharge lamp.
In recent years, maintenance-free electrodeless discharge lamps (hereinafter, referred to as “electrodeless fluorescent lamps”) having a long life that is provided with a phosphor layer inside the lamp have been put to practical use and been under development. Lamps of this type are not provided with electrodes inside the discharge vessel, and discharge occurs in the following manner: a luminous material in the discharge vessel is electromagnetically coupled by high frequency electromagnetic field generating means for generating an electromagnetic field inside the discharge vessel enclosing the luminous material so that a closed loop discharge is formed. The ultraviolet rays that are generated by this discharge are converted to visible light by the phosphor applied onto the inner surface of the discharge vessel. In general, the high frequency electromagnetic field generating means is, for example, an exciting coil through which a high frequency current flows.
Since electrodeless fluorescent lamps include no electrodes inside the discharge vessel, they operate regardless of depletion of an emissive material applied onto electrodes on which the life of a fluorescent lamp depends. Therefore, the electrodeless fluorescent lamps are characterized by having a long life.
Conventionally, in the electrodeless fluorescent lamps, a heat-resistant adhesive such as silicone is poured into a portion where a discharge vessel is in contact with a case for housing a high frequency power connected to an exciting coil to secure the discharge vessel to the case. This method is used, especially for self-ballasted fluorescent lamps with electrodes having a life of about 6000 hours.
However, this method causes detachment of the adhesive because of the contraction of the adhesive due to the heat of the discharge vessel or decrease of the adhesion strength between the discharge vessel and the case due to the degradation or change in quality of the adhesive over time. In particular, since the electrodeless fluorescent lamps have long lives, the decrease of the adhesion strength is particularly problematic.
In order to solve these problems, Japanese Laid-Open Patent Publication No. 9-320541 discloses a technique for compensating for the decrease of the adhesion strength by providing a recess or a protrusion that is engaged with each other in a case and a discharge vessel in a portion in which the case including a ballast is in contact with the discharge vessel.
FIGS. 10A and 10B
show the electrodeless fluorescent lamp disclosed in the above publication.
FIG. 10A
is a cross-sectional view of the entire electrodeless discharge lamp, and
FIG. 10B
is an enlarged view of the portion where the case is in contract with the discharge vessel. In the drawing, reference numeral
101
denotes a discharge vessel,
102
denotes a phosphor,
303
denotes a translucent conductive film,
304
denotes a regular incandescent lamp base,
305
denotes a blast,
306
denotes ferrite,
307
denotes an exciting coil,
308
is a case cover,
309
denotes a protrusion and
210
denotes a recess.
In the method of engaging the discharge vessel to the case with the recess and the protrusion as shown in
FIGS. 10A and 10B
, the discharge vessel and the case are engaged with each other directly, so that it is necessary that the discharge vessel matches the shape of the case. On the other hand, the size of the case is determined by the magnitude of the high frequency power to be housed. Thus, the degree of freedom in the design of the shape of the discharge vessel that affects the discharge characteristics significantly may be restricted by the size of the case.
Furthermore, in the above method, there is nothing between the discharge vessel and the high frequency power enclosed in the case, visible light generated in the discharge vessel leaks to the high frequency power or the inside of the case, so that the ratio of the light that can be utilized for effective illumination of an object with respect to the light generated in the discharge vessel (hereinafter, referred to as “light utilization efficiency”) is insufficient and the light utilization efficiency is low.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind, it is a main object of the present invention to provide an electrode discharge lamp in which the decrease of the adhesion strength between the discharge vessel and the case is suppressed. It is another object to provide an electrodeless discharge lamp in which the light utilization efficiency is improved.
A first self-ballasted electrodeless discharge lamp of the present invention includes a discharge vessel having a cavity, an induction coil that is inserted into the cavity, a ballast for supplying power to the induction coil, a case for covering the ballast; and a lamp base provided in the case. The discharge vessel is secured to the case via a holder. A part of the discharge vessel and a first portion of the holder are engaged with each other to constitute a combination structure. A second portion of the holder and a part of the case are engaged with each other to constitute a combination structure.
It is preferable that at least a part of the holder on the side of the discharge, vessel has a function of reflecting light from the discharge vessel.
It is preferable that at least a part of the holder has a function of shielding a magnetic field from the discharge vessel.
A second self-ballasted electrodeless discharge lamp of the present invention includes a discharge vessel having a cavity, an induction coil that is inserted into the cavity, a ballast for supplying power to the induction coil, a case for covering the ballast, and a lamp base provided in the case. The discharge vessel is secured to the case via a holder. The induction coil includes a core and a winding. The holder has a cylindrical bobbin portion whose surface is wound with the winding and into which the core is inserted. A part of the discharge vessel and a first portion of the holder are engaged with each other to constitute a combination structure. A second portion of the holder and a part of the case are engaged with each other to constitute a combination structure.
In one preferable embodiment, a first end of the core is positioned in the case, and a heat sink is provided in the first end of the core.
A third self-ballasted electrodeless discharge lamp of the present invention includes a discharge lamp having a cavity, an induction coil that is inserted into the cavity, a ballast for supplying power to the induction coil, a case for covering the ballast, and a lamp base provided in the case. The discharge vessel is secured to the case via a holder. A part of the discharge vessel and a first portion of the holder are engaged with each other to constitute a combination structure. A second portion of the holder and a part of the case are engaged with each other to constitute a combination structure. The holder has a circuit holder portion on which the ballast is placed.
In one preferable embodiment, the induction coil includes a core and a winding. The holder has a cylindrical bobbin portion whose surface is wound with the winding and into which the core is inserted. A first end of the core is positioned in the case, and a heat sink is provided in the first end of the core.
In one preferable embodiment, the part of the discharge vessel is a protrusion extending to a second direction substantially perpendicular to a first direction, the induction coil being inserted in the first direction. The first portion of the holder is a recess that clamps the protrusion and has a substantially U-shaped cross section. A notched portion having a size that allows the protrusion to move in a direction substantially perpendicular to the second direction is provided in a periphery of the recess of the holder. The holder has an engagement structure that allows the protrusion to be engaged with the re
Arakawa Takeshi
Hashimotodani Kiyoshi
Itaya Kenji
Kawasaki Mitsuharu
Kurachi Toshiaki
Harness & Dickey & Pierce P.L.C.
Matsushita Electric - Industrial Co., Ltd.
Patel Vip
Quarterman Kevin
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