JP2006059819A - Phosphor coating structure for electrode discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode-less discharge lamp which can be generated efficiently at low cost. <P>SOLUTION: During the lamp is turned on, a cavity 16 is exposed to a wall heat load higher than the exterior wall of the lamp globe 12. In order to resist the higher well heat load, a triphosphate phosphor 30 is used instead of a halo-phosphate phosphor 32 used for the exterior wall of the lamp globe. To perform two types of phosphor coating for a single lamp globe at a reasonable cost, the cavity and the exterior wall are separately coated and then these two elements are joined to make a finished product of the lamp globe. The joint of the cavity and the exterior globe is located under the upper rim of a housing so that it does not appear in sight in the finished lamp. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of a phosphor coating applied to a bulb portion of an electrodeless discharge lamp. The present invention relates to a phosphor coating, and more particularly to a phosphor coating structure which attempts to solve the difference in wall loading characteristics existing in an electrodeless discharge lamp.

  It is noted that electrodeless discharge lamps greatly contribute to the realization of an electrical configuration that reduces power requirements, thereby avoiding the construction of power facilities with high operating costs. The attribute of the electrodeless discharge lamp comes from the improved energy efficiency of such a device and is expected to have a long life because it eliminates electrode elements that shorten the life. An example of an electrodeless discharge lamp is disclosed in U.S. Pat. No. 4,010, which discloses that an ionization medium is contained in a lamp tube and an RF signal is introduced so as to be close to the ionization medium to form a discharge state. It can be found in No. 400. By using a suitable phosphor, visible light is generated by such a discharge. In order to generate this RF signal, the electrodeless discharge lamp has a stable circuit structure disposed in the lamp base, and such a stable circuit structure ionizes the RF signal by causing a coil member to enter the lamp tube. Inductively coupled to the medium.

As with any conventional fluorescent lamp, an electrodeless discharge lamp requires a phosphor layer to convert the discharge from the ionized medium into visible light. A typical practice in a fluorescent lamp manufacturing process is to use a halophosphate phosphor and mix the phosphate with it or add a relatively small amount of phosphate to it to obtain the required final color. Can do. Halophosphate phosphors are widely used because they are relatively inexpensive, and because of their preferred efficiency, low cost, and wide color tolerance. However, for applications in small fluorescent lamps, the use of halophosphate phosphors is unsuitable because high numerical wall heat load characteristics are typically formed. This is because these materials tend to deteriorate rapidly under high wall heat load conditions. In such a case, it is usually necessary to use a more expensive rare earth phosphor. In the electrodeless discharge lamp, the wall surface heat load characteristics change depending on the lamp tube portion, but the above-mentioned heat load characteristics are sufficient in the vicinity of the cavity region surrounding the coil member to which the RF signal is inductively coupled. Higher, closing the way of using halophosphate phosphors in such areas. One way to mitigate degradation of the phosphor by using a halophosphate phosphor is to cover the entire inner surface of the lamp bulb with a rare earth phosphor. Although such a feature brings about a longer life of the light source, the cost of the lamp is remarkably increased by using a relatively expensive rare earth phosphor. Another way to alleviate this problem is to mask between certain locations of the inner wall of the lamp tube and perform a separate deposition process at each location where a different phosphor should be used. Such a configuration is generally costly because the manufacturing steps required to perform masking and multiple coatings are expensive.
US Patent No. 4,010,400

  Thus, the phosphor coating structure is cost effective as a result of using different phosphors (using expensive rare earths only where needed) based on wall heat load requirements, such as masking and multiple coating steps It is an object of the present invention to provide an electrodeless discharge lamp without adding such various processes.

  An electrodeless discharge lamp constructed according to the principle of the present invention has a lamp tube filled with a mercury filling and a rare gas, and the rare gas is an RF signal generated by a stable circuit disposed in the lamp base. It has a lamp tube that is excited from the introduction to the discharge state. The lamp tube is disposed so as to at least partially surround the coil member, and an RF signal is generated from the coil member. The phosphor coating structure on the lamp tube is effectively formed at a low cost and can be easily implemented for mass production processes. The outer part of the lamp tube is spaced apart with respect to the coil member, while the inner cavity projects into the lamp tube along its central axis. The inner cavity along this central axis is sized to receive the coil member inserted therein and to provide a higher wall heat load on the inner cavity closer to the coil member than the outer part of the lamp bulb. It is decided. The joining region of the lamp tube is formed by joining the inner cavity portion to the outer portion of the lamp tube at the lowermost part of the lamp tube. The lowermost part of the lamp tube is inserted on the lamp base in order to hold the lamp tube on the lamp base. The rare earth phosphor coating is applied to the inner cavity, but either the halophosphate phosphor or the fluorescent phosphate material is applied to the inner surface of the outer portion of the lamp bulb. The manufacturing process for joining the internal cavity to the outer part of the lamp tube is performed after the phosphor coating is applied, thereby eliminating the need for masking operations in the coating process.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, the low-pressure electrodeless fluorescent lamp 10 includes a lamp tube 12 having an outer tube portion 14 and an inner cavity portion shown as a recessed (reentrant) cavity portion 16. The recessed hollow portion 16 is basically in the shape of a circle and protrudes into the outer tube portion 14 along its central axis. An exhaust sealing tube 18 is provided along the central axis of the recessed cavity portion 16, and the exhaust sealing tube 18 is formed by joining the recessed cavity portion 16 and the outer tube portion 14 to form the lamp tube 12. And projecting downward beyond the junction indicated by 20 in the figure.

  The outer bulb portion 14 basically has the same shape as a finished product of a conventional incandescent reflector lamp. However, other shapes may be employed for the outer lamp tube 14. For example, the outer bulb 14 may have the same shape as a well-known A-line type lamp or a decorative globe lamp.

  Regardless of the shape of the outer bulb portion 14, the lower portion of the outer bulb portion 14 that faces each other in the outer bulb portion and the recessed cavity portion of the lamp bulb 12 and is ultimately integrated at the joint 20. The region 14 a and the lower region 16 a of the recessed cavity 16 are located inside the upper rim region of the base housing 22. As will be described in detail later, in this respect, by arranging the joint portion 20, the coating treatment of the fluorescent material can be performed with a somewhat relaxed strictness. Further, by adopting a lamp manufacturing method in which the outer bulb 14 is formed separately from the forming process of the recessed cavity 16, the phosphor coating is formed by joining these two parts in the final finishing process of the lamp. Each part can be done individually before being done. In this embodiment, the present invention can perform the phosphor film formation on the outer bulb portion 14 separately from the application to the recessed cavity wall, and thereby coat the other portions with different fluorescent materials. When this is done, it is not necessary to mask that part.

  As further shown in FIG. 1, the electrodeless discharge lamp 10 of the present invention generates a toroidal discharge phase 23 in the lamp bulb 12. Such a discharge phase 23 is generated by introducing radio frequency (RF) energy into the filling contained in the lamp tube. In this case, conventionally known materials used for standard fluorescent lamps are used as the filler. RF energy is generated by the resonant circuit portion of the ballast circuit 24 disposed within the housing base 22. The resonance circuit section is composed of an excitation coil 26 having a winding section 26a and a core section 26b, and a capacitor 28. This stabilization circuit excites the resonance circuit unit by a condition signal converted from the line power supply.

By generating and maintaining the discharge phase 23 in the lamp tube 12, the recessed cavity 16 of the lamp tube 12 has a higher wall surface thermal load value (W / cm ² ) than the outer tube portion 14. . In order not to shorten the actual life of the electrodeless discharge lamp 10, which is expected to have a long life, in particular, the phosphor coating applied to the wall surface of the recessed cavity 16 is made from triphosphate. It is necessary to use a phosphor coating. As shown in FIG. 2, the triphosphate phosphor coating 30 is applied on the wall surface of the recessed cavity 16 facing the inner space outside the lamp bulb 12. The triphosphate phosphor coating 30 can typically use a material for a normal small fluorescent lamp that is readily available on the market.

  Unlike the wall surface heat load condition experienced by the recessed cavity 16, the outer tube portion 14 of the lamp tube 12 has such a low heat load, and a relatively inexpensive halophosphate material is used. it can. This material is a fluorescent material similar to that used in relatively large fluorescent lamps of the 2 foot type or the 4 foot type. As shown in FIG. 2, the different fluorescent material 32 is shown as having a different particle size than the fluorescent material 30 used in the recessed cavity. Further, as shown in FIG. 2, the lamp 10 is a reflector lamp, and has a light-reflective coating 34 in the lower half portion extending to the maximum diameter portion of the lamp tube on the wall surface of the recessed cavity 16. The maximum diameter portion is indicated by a dividing line (two-dot chain line) indicated by an AA line.

  In the covering step for forming the phosphor coating on the outer tube bulb 14 of the lamp tube 12 and the wall surface of the recessed cavity 16, the recessed cavity 16 and the outer tube 14 are joined. Strictness is not required for the portion of the lamp tube 12. In practice, the joint 20 is not visible in the final product and is covered by the upper rim of the housing base 22. Further, in the processing step applied to the lamp bulb 12 having a phosphor coating as a final product assembled to the housing portion 22 and the stable circuit portion 24, each of the outer bulb portion 14 and the cavity portion 16 is individually coated. It will be understood that it is simplified by the fact that it is performed without the need for a masking step to apply the material. After such an individual coating process is completed, the outer bulb 14 and the recessed cavity 16 are joined to form the final lamp bulb, which allows the expensive triphosphate material to be It is possible to achieve a relatively inexpensive element configuration that is used only in a region required in accordance with the thermal load characteristics.

  The embodiments described above are preferred embodiments of the present invention, but various modifications may be made to these embodiments without departing from the scope of the present invention as long as they are subject to the appended claims. Is possible.

FIG. 1 is a cross-sectional side view of an electrodeless lamp constructed in accordance with the present invention. FIG. 2 is an enlarged side sectional view showing the lamp tube portion of FIG. 1 for showing the phosphor coating structure of the present invention.

Explanation of symbols

10 Electrodeless discharge lamp 12 Lamp tube 16 Cavity 22 Housing base

Claims (1)

In an electrodeless discharge lamp having a lamp tube filled with mercury and a rare gas that is excited to a discharge state by introducing an RF signal generated by a stable circuit disposed in a base portion, the lamp tube transmits an RF signal. It is arranged so as to at least partially surround the generated coil member, and a phosphor film is formed on the lamp tube, and the electrodeless discharge lamp comprises:
An outer portion of the lamp tube positioned away from the coil member;
A wall surface that is dimensioned to project into the lamp tube along its central axis and to support the coil member, the wall surface being higher than the value experienced by the outer portion of the lamp tube The part governed by the heat load condition;
A joint area of the lamp tube connecting the inner cavity to an outer portion of the lamp tube;
A rare earth phosphor coating applied to the inner cavity of the lamp bulb; and
An electrodeless discharge lamp comprising: a phosphor coating composed of at least one of a halophosphate and a phosphate material applied to an inner surface of the outer portion of the lamp tube.

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