JPS6336937Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a metal vapor discharge lamp with a built-in ballast in which a resistor is connected in series with an arc tube within the outer bulb of the lamp.

Recently, metal sodium, a buffer metal such as mercury or cadmium, and a starting rare gas are sealed in an arc tube made of a translucent ceramic tube with excellent sodium resistance, such as a polycrystalline alumina tube, and light is emitted within the outer bulb of the lamp. A high-efficiency high-pressure sodium lamp with a built-in ballast is being considered, with a resistor connected in series with the tube.

Polycrystalline alumina tubes, which are commonly used as arc tubes for high-pressure sodium lamps, are different from quartz tubes used for mercury lamps and metal halide lamps because they do not interact with the enclosed metal sodium even at high temperatures when the lamp is lit. It has excellent reaction resistance and therefore has excellent heat resistance without sodium leakage.
For this reason, arc tubes using polycrystalline alumina tubes can be installed inside the lamp's outer bulb, which is kept in a high vacuum, which reduces heat loss from the arc tube and increases efficiency.
It is designed to have a long lifespan.

In conventional mercury lamps with a built-in ballast and certain types of metal halide lamps, nitrogen gas or a mixture of nitrogen gas and an inert gas is generally sealed in the outer bulb.

On the other hand, high-pressure sodium lamps are kept in a high vacuum inside the outer bulb, as mentioned above, and in order to design a high-pressure sodium lamp with a built-in ballast, taking advantage of the high efficiency and long life of high-pressure sodium lamps, high-melting point metals are used. It is necessary to design the operating temperature of the tungsten coil to be sufficiently low (preferably about 1400° C. or lower) to suppress evaporation of tungsten as much as possible, and to sufficiently extend the life of the arc tube. Under such conditions, installing the tungsten coil compactly inside the outer bulb will reduce short circuits and short circuits between the pitches during its life, compared to the case where the outer bulb contains gas.
In order to prevent deformation, the coil diameter of the tungsten coil cannot be made very thick, and as a result, the coil length is approximately 1.5 times or more than the coil length of a mercury lamp or metal halide lamp with a built-in ballast, which is extremely difficult. This was an obstacle to the development and popularization of high-pressure sodium lamps with built-in ballasts.

The purpose of this invention is to solve the above-mentioned problems.The present invention consists of an arc tube made of a translucent ceramic tube, a solid resistor and a coiled high-melting point metal arranged in series in an outer sphere kept in a vacuum. The present invention aims to lower lamp costs and provide a highly reliable metal vapor discharge lamp with a built-in ballast by connecting a resistor and encapsulating it in an outer bulb kept in a vacuum. The solid resistor referred to herein refers to a solid molded resistor such as a carbon film resistor with excellent heat resistance, a cermet, silicon carbide, or a ceramic substrate integrally molded with a metal resistor.

Hereinafter, the present invention will be explained based on examples.

The figure is a schematic diagram of the 400 watt high-pressure sodium lamp with a built-in ballast according to the present invention. Inside the outer bulb 1 kept in a high vacuum, an arc tube 2 made of a polycrystalline alumina tube is placed. A tungsten coil 3 is connected in series to one end of the arc tube 2, and a solid resistor 4 made of a carbon film resistor is connected in series to the other end. Further, a proximal conductor 5 is provided as a starting auxiliary external electrode close to the outer surface of the arc tube. This proximity conductor 5 is connected to a high voltage pulse terminal of a high voltage pulse generator 7 housed in a base 6. The arc tube 2 is filled with 5 mg of metallic sodium, 30 mg of mercury, and 30 torr of starting auxiliary gas. When power is applied to this lamp, the xenon gas, which is a starting auxiliary gas sealed in the arc tube, is discharged, the arc tube 2 lights up, and a stable discharge is caused by the tungsten coil 3 and solid resistor 4, which are the ballasts built into the lamp. transition to the state. A tungsten coil 3 having a wire diameter of 0.23 mm and a coil length of about 90 mm is compactly held by a support 8 having a molybdenum wire fixed to an insulator. The operating temperature of this tungsten coil cannot be made high enough for the light emitted from the coil to contribute to improving the lamp luminous flux and color rendering, but is rather affected by the shielding of light from the arc tube 2 and the evaporation of tungsten from the tungsten coil during the lamp life. It is installed approximately midway between the arc tube and the head of the outer bulb in order to prevent this and to take into account the heat resistance of the glass outer bulb. Furthermore, since the solid resistor 4, which is a carbon film resistor, is made of alumina and carbon, the temperature rises to approximately 800°C, but mechanically,
There is no thermal change, and even if it is installed in a narrow space at the end of the outer sphere on the base side, there is no risk of short circuit with other parts. In a 400 watt high pressure sodium lamp with built-in ballast, the power consumed by the resistor is approximately 220 watts, but the power consumed by the tungsten coil is
It is preferable to keep the power to about 100 watts from the viewpoint of the coil shape. It is possible to use only a solid resistor as the resistor, but solid resistors have a small change in resistance value due to temperature changes, so the lamp power tends to fluctuate due to fluctuations in the arc tube voltage and lamp lighting voltage. Because of its power consumption, the solid resistor must be considerably large, which is not practical.

In this way, by applying solid resistors not only to high-pressure sodium lamps but also to metal vapor discharge lamps with a built-in ballast whose outer bulb is a vacuum, the industrial effects include improving reliability and reducing costs. big.

[Brief explanation of the drawing]

The figure is a schematic diagram of a 400-watt high-pressure sodium lamp with built-in ballast according to the present invention. 1... Outer sphere, 2... Arc tube, 3... Tungsten coil, 4... Solid resistor.

Claims (1)

[Scope of utility model registration request] A stable device characterized by an arc tube made of a translucent ceramic tube inside an outer sphere kept in a vacuum, and a solid resistor and a coiled resistor made of a high-melting point metal connected in series with the arc tube. Built-in metal vapor discharge lamp.