Electric lamp and discharge devices: systems – Condenser in the supply circuit – Arc machining
Patent
1982-11-02
1985-05-14
Dixon, Harold
Electric lamp and discharge devices: systems
Condenser in the supply circuit
Arc machining
315244, 315241R, 361321, H05B 3700
Patent
active
045174962
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention provides a lighting apparatus for a discharge lamp which is miniaturized and weight-reduced to a substantial degree as compared with conventional lighting apparatus for a discharge lamp. Also, the present invention provides a means to miniaturize and reduce the weight of a discharge lamp having incorporated therein a current limiting element.
BACKGROUND OF THE INVENTION
It is known that current limiting elements or ballasts necessary for lighting a discharge lamp include induction elements such as a magnetic core, such as silicon steel sheet, on which a copper wire is wound, capacitive elements using a dielectric such as plastic film and paper and resistance elements using a nichrome wire. All these elements have enough current capacity necessary for operating a discharge lamp. However, they have the disadvantage that their weights and sizes are large. Moreover, the resistance elements exhibit a high power loss.
Accordingly, an object of the present invention is to improve the above-mentioned disadvantages of the conventional arts and to provide a lighting apparatus for a discharge lamp which is small-sized and exhibits a low power loss.
The lighting apparatus for a discharge lamp according to the present invention is characterized in that there is used a current limiting device utilizing the dependency of an impedance of a ferroelectric polycrystalline ceramic comprising mainly barium titanate on a voltage.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit of a lighting apparatus for a discharge lamp using a capacitor as a current limiting element;
FIG. 2 is a voltage-current wave form for the circuit shown in FIG. 1;
FIG. 3 is a hysteresis curve of a conventional dielectric;
FIG. 4 is a hysteresis curve of a conventional BaTiO.sub.3 ceramic having a high dielectric constant;
FIG. 5 is a circuit for measuring the characteristics of a current limiting element used in the lighting apparatus for the present invention;
FIG. 6 is a voltage-current wave form of the current limiting element according to the present invention;
FIG. 7 is a D-E hysteresis characteristic of the current limiting element according to the present invention;
FIGS. 8, 9 and 10 respectively are a graph illustrating experimental results regarding the dependency of an impedance of the current limiting elements according to the present invention on a voltage;
FIG. 11 is a view illustrating one embodiment of the structure of the current limiting element according to the present invention;
FIG. 12 is a circuit of the lighting apparatus according to the present invention;
FIG. 13 is an operational wave form of each portion of the apparatus shown in FIG. 12;
FIG. 14 is another circuit of the lighting apparatus of the present invention;
FIG. 15 is a view illustrating one embodiment of the structure of the discharge lamp according to the present invention;
FIG. 16 is still another circuit of the lighting apparatus according to the present invention; and
FIG. 17 is an operational wave form of each portion of the apparatus shown in FIG. 16.
PREFERRED EMBODIMENTS OF THE INVENTION
The present invention is illustrated with reference to a circuit operation of a lighting apparatus for a discharge lamp in which a conventional capacitive element is used as a current limiting element for a discharge lamp, and the characteristics required as the capacitive element.
FIG. 1 is a circuit of a lighting apparatus for a discharge lamp. Referring to FIG. 1, the reference numeral 1 represents a source of alternating current, the reference numeral 2 is a conventional capacitor using a conventional dielectric such as paper, and the reference numeral 3 is a discharge lamp. FIG. 2 shows wave forms of the voltage V.sub.1 of the current source, the voltage V.sub.T of the discharge lamp, the current A.sub.T of the discharge lamp and the voltage V.sub.C of the capacitor. When the voltage V.sub.T of the discharge lamp reaches the discharge starting voltage (V.sub.BO) at a phase .theta..sub.1, the discharge lamp 3 sta
REFERENCES:
patent: 3975658 (1976-08-01), Emtage et al.
patent: 3996495 (1976-12-01), Herman
patent: 4119886 (1978-10-01), Jyomura et al.
patent: 4347462 (1982-08-01), Adachi et al.
patent: 4360762 (1982-11-01), Yamamoto et al.
patent: 4381476 (1983-04-01), Adachi et al.
Adachi Hiromi
Iwaya Shoichi
Dixon Harold
Mitsubishi Denki & Kabushiki Kaisha
TDK Electronics Co. Ltd.
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