Electric lamp and discharge devices – With temperature modifier – Having heat conducting path
Reexamination Certificate
2002-10-31
2004-09-21
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With temperature modifier
Having heat conducting path
C313S318010, C313S011000
Reexamination Certificate
active
06794801
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications JP2001-335662 filed on Oct. 31, 2001, JP2001-397205 filed on Dec. 27, 2001 and JP2002-97684 filed on Mar. 29, 2002, the entire contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to a compact selfballasted fluorescent lamp and a luminaire.
BACKGROUND OF THE INVENTION
A compact selfballasted fluorescent lamp is composed of one integrated fluorescent arc tube whose discharge path is formed by crooked tubes and a housing for supporting the fluorescent arc tube. The housing has a bulb-base and accommodates a lighting circuit module for lighting the fluorescent arc tube.
In such a compact selfballasted fluorescent lamp, there is a great concern that the temperature rise within the housing during lighting causes a bad influence on the circuit components of the lighting circuit. In order to prevent the temperature rise within the housing caused by the heat of the lighting circuit module, it is known as a technique of filling synthetic resin in the space between the circuit board and the housing so as to contact them with each other, as disclosed in, e.g., the JP-A 57-50762.
In the conventional technique, synthetic resin is filled in the space between the circuit board and the inner wall of the housing, contacts the circuit components mounted on the circuit board and the inner wall of the housing. Thus heat of the lighting circuit module utilizing the electronic ballast is dissipated by conducting through the synthetic resin. Hereby, while the lighting efficiency of the fluorescent arc tube being improved, the temperature rise in the lighting circuit module could be depressed. Further, it is not necessary to define an air hole in a housing and to use an expensive glove having high heat resistance either.
However, as the compact selfballasted fluorescent lamp is high-powered and miniaturized the space for accommodating the luminaire becomes much more narrow. As a result, the temperature within the housing rises further. In case of an inverter circuit, wherein the lighting circuit mounted in a compact selfballasted fluorescent lamp is composed of circuit components, some circuit components relatively vulnerable to heat are included in them. Thus, it is necessary to prevent overheating inside the housing by more efficiently dissipating heat in the housing in order to protect the circuit components. Furthermore, the practical specification of the synthetic resin for dissipating heat inside the housing has to be adopted in consideration of the heat resistance of the circuit board or circuit components. However, neither detailed analyses nor sufficient developments for making heat inside the housing not to defect the lighting circuit module have been proceeded.
SUMMARY OF THE INVENTION
The present invention has an object to provide a compact selfballasted fluorescent lamp which has a high reliability in the lighting circuit module by efficiently dissipating heat inside the housing, in consideration of dissolving the problems as described above.
A compact selfballasted fluorescent lamp according to the first aspect of the invention, comprising
a fluorescent arc tube forming a crooked discharge path, a housing comprised of a first end portion open to be fit thereon with a bulb-base (hereinafter referred to as bulb-base applying end portion), a middle portion and a second end portion open to be mounted thereto with the fluorescent arc tube (hereinafter referred to as fluorescent arc tube module applied portion), a lighting circuit module accommodated in the housing, the unit being provided with a circuit board and two or more circuit components mounted on the circuit board for constituting a lighting circuit for lighting the fluorescent arc tube, and a thermal conductor having a thermal conductivity of 0.1 W/(m·K) or more, which is filled in the housing, extending upwards from a components mounting side of the circuit board of the lighting circuit module and contacting with the inner wall of the housing lying on the side of the first end portion of the housing, thereby covering at least one of the circuit components of the lighting circuit.
The thermal conductor is desirable to have heat conductivity higher than air, and have moderate fluidity at the time of filling the thermal conductor in the housing.
In order to efficiently dissipate heat of the lighting circuit module developed by itself or conducted from the fluorescent arc tube, the thermal conductor filled in the housing in proximity to the circuit components developing a large amount of heat or contacted with a part of or whole surface of the circuit component, and also it is desired to contact with the housing inner wall as large an area as possible.
The circuit components subject to the heat dissipation by the thermal conductor may be not only those developing a large amount of heat but also those having low heat resistance. That is, it is because the thermal conductor has a function to prevent heat affection on the circuit components having low heat conductor.
A housing for accommodating the lighting circuit module for lighting the fluorescent arc tube is made of synthetic resin or a metal with thickness of 0.5 to 3 mm in general.
An area surrounding the circuit components of the lighting circuit module inside the housing is relatively large. Accordingly, the thermal conductor is able to contact with the housing inner wall over relatively large area, so that it is able to conduct and dissipate heat developed inside the housing to the outside.
In order to conduct heat from the circuit components to the housing efficiency, it needs to enhance the thermal conductivity of the thermal conductor. It was experimentally confirmed that it was able to efficiently lower the temperature inside the housing when the thermal conductor has a thermal conductivity more than 0.1 W/(m·K). As the thermal conductor having such thermal conductivity, for example, silicone resin or epoxy resin are suitable.
In case of an integrated crooked fluorescent arc tube, its cooked portions may have a semicircle shape or a horseshoe shape. Alternatively, adjacent two straight tubes of parallel-aligned two crooked tubes may be coupled through a coupling tube communicating with their sides near the respective tube ends in order to form a crooked discharge path.
In the compact selfballasted fluorescent lamp according to the first aspect of the invention, at least one of the circuit components mounted on the circuit board of the lighting circuit module is covered with the thermal conductor whose thermal conductivity is more than 0.1 W/(m·K), while the thermal conductor contacts with the inner wall of the housing, thereby it is able to efficiently dissipate heat developed by the circuit components via the thermal conductor.
A compact selfballasted fluorescent lamp according to the second aspect of the invention, comprising a fluorescent arc tube forming a crooked discharge path, a housing having a bulb-base applying end portion, a middle portion and a second end portion open to be mounted thereto with the fluorescent arc tube, a lighting circuit module accommodated in the housing, the unit being provided with a circuit board and two or more circuit components mounted on the circuit board for constituting a lighting circuit for lighting the fluorescent arc tube, and a thermal conductor filled in the housing in contacting with the inner wall of the housing, thereby covering some circuit components of the lighting circuit module, wherein the housing excepting the bulb-base applying end portion has an outer surface area per unit lamp power not exceeding 500 mm
2
/W.
The term “bulb-base fitting portion of the housing” means a cylindrical portion formed on one end of the housing, whereon the bulb-base is to be fit.
When the housing excepting the bulb-base applying end portion has an outer surface area per unit lamp power more than 500 mm
2
/W, it suffers affections of heat
Araki Tsutomu
Hiraoka Toshiyuki
Matsumoto Shin-ichiro
Matsunaga Yoshiyuki
Toda Masahiro
Colón German
Patel Nimeshkumar D.
Pillsbury & Winthrop LLP
Toshiba Lighting & Technology Corporation
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