JPH0762992B2 - Reflective metal halide lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a reflective metal halide lamp in which a metal halide is enclosed.

(Prior Art) A metal halide lamp in which a metal halide is enclosed in an arc tube improves the lamp efficiency by using sodium halide as the metal halide, and makes the color temperature close to an incandescent color, and further, the arc. This kind of lamp has become the mainstream at present because of the effects of stabilizing the lamp.

In this way, the reflective type in which the metal reflection film is provided on the inner surface of the outer tube of the metal halide lamp containing sodium halide has a function of reflecting visible light in the lamp itself, so it reflects special visible light in addition to the lamp. Since no reflecting device is required, the cost of the device as a whole is low. On the other hand, this type of lamp is widely applicable to spot lighting, decoration, outdoor lighting, etc. Therefore, it is strongly desired to put a reflective metal halide lamp containing sodium halide with high lamp efficiency into practical use.

By the way, the reflection type of the metal halide lamp containing sodium halide has the following drawbacks.
That is, when ultraviolet rays emitted from the arc tube during lighting are applied to the metal reflection film provided on the inner surface of the outer tube, photoelectrons are emitted from the metal forming the reflection film, and the photoelectrons are diffused and adhere to the outer surface of the bulb. Then, the arc tube is negatively charged. The arc tube bulb of a metal halide lamp is usually made of quartz glass, and the interstitial distance of silicon oxide forming the quartz glass is larger than that of sodium ions in the arc tube. It is drawn to the potential by the negative photoelectrons, passes through the quartz arc tube bulb, and disappears outside the arc tube. Therefore, the amount of luminescent sodium metal inside the arc tube is decreased, so that the lamp efficiency is decreased, and the excess free halogen is increased, so that the lamp voltage is increased and the life is shortened.

In order to deal with such a problem, for example, Japanese Utility Model Publication No. 50-36869.
In Japanese Patent Laid-Open Publication No. 2004-242242, the metal reflection film provided inside the outer tube is configured to be insulated from the conductor inside the outer tube to reduce the photoelectron emission amount from the metal reflection film, or to remove photoelectrons from the metal reflection film. A method is shown in which photoelectrons are again drawn back to the metal reflection film that is electrically charged to prevent the photoelectrons from adhering to the outer surface of the arc tube.

However, in this method, since the area of the metal reflection film is quite large, a considerable amount of photoelectrons are emitted by the time the metal reflection film is charged to the positive charge for pulling back the photoelectrons, and the effect is actually small. .

Further, in JP-B-49-28364 and JP-B-49-28365, the conductor of the lamp part and the metal reflection film are brought into contact with each other through a rectifier to set the metal reflection film to a positive or zero potential.
A method for preventing sodium escape in the arc tube is shown.

However, in the case of this method, a means for firmly connecting the contact portion by welding or the like cannot be used in manufacturing, and since the contact is simply made, the contact portion lacks reliability, and a lamp with no effect is generated, In addition, when the contact portions are separated from each other and there is a slight gap, inconvenience such as generation of internal discharge may occur.

Further, in JP-A-61-232553, a translucent insulating shield is arranged inside an outer tube provided with a metal reflection film on the inner surface so as to surround an arc tube containing sodium halide. According to the above, a reflection type metal halide lamp is described which limits the emission of photoelectrons from the metal reflection film and prevents the emitted photoelectrons from adhering to the outer surface of the arc tube to prevent the disappearance of sodium outside the arc tube. There is.

However, the mounting structure of the lamp having such a structure becomes complicated, and when the lamp power increases, the size of the arc tube becomes large, and the translucent insulating and shielding body surrounding the lamp inevitably becomes large. However, a problem may occur in the strength of the mount that supports them.

(Problems to be Solved by the Invention) As described above, in the reflection type metal halide lamp in which the metal reflection film is provided on the inner surface of the outer tube, photoelectrons emitted from the metal reflection film during lighting adhere to the outer surface of the arc tube. In addition, sodium ions in the arc tube are lost to the outside of the arc tube to lower the lamp efficiency, and the lamp voltage is increased by increasing the amount of free halogen to shorten the lamp life. Further, each of various means for limiting the emission of photoelectrons from the metal reflection film provided on the inner surface of the outer tube has drawbacks such that the effect is insufficient and the configuration is complicated.

Therefore, the present invention has been made in consideration of such a conventional drawback, and in spite of its simple structure, a reflection type metal halide lamp capable of reflecting visible light while preventing the disappearance of sodium enclosed in the arc tube is provided. The purpose is to provide.

[Structure of Invention]

(Means for Solving the Problems) The reflection type metal halide lamp of the present invention has a quartz arc tube in which at least sodium halide is enclosed as a metal halide and is housed in an outer tube in which an inert gas is enclosed. Moreover, the outer surface of the outer tube is provided with a visible light-reflecting metal reflective film that emits photoelectrons when receiving ultraviolet rays.

(Operation) According to such a configuration, even if photoelectrons are emitted from the metal reflection film by the emitted light from the arc tube, the metal emission film is provided on the outer surface of the outer tube, so that the photoelectrons are not generated in the outer tube wall. It is blocked by and does not fly to the outer surface of the arc tube. Therefore, the disappearance of sodium ions outside the arc tube does not occur. Moreover, the object can be achieved with a simple configuration in which the metal reflection film is provided on the outer surface of the outer tube.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

The figure shows the schematic structure of 400W class reflective metal halide lamp. (1) For example, an outer tube made of hard glass,
Except for the front light-transmitting portion (2), a metal reflection film (3) made of, for example, a vapor-deposited film of aluminum is applied to the outer surface of the outer surface. Needless to say, the vapor deposition film of aluminum is a film that reflects visible light.

Further, an inert gas such as nitrogen gas is sealed inside the outer tube (1), the open end is sealed by the stem (4), and the base (5) is mounted. (6) is an arc tube housed in the outer tube (1), and is a sealing part (8) formed by heating and crushing both end openings of a quartz glass arc tube bulb (7).
A pair of electrodes (9) and (9) are provided oppositely to (8), and these electrodes (9) and (9) are hermetically sealed to the sealing parts (8) and (8). ), (10) through external lead wire (1
1) and (11), and a predetermined amount of starting rare gas, mercury and sodium iodide and scandium iodide as metal halides are enclosed in the arc tube (6).

Further, the external lead wires (11), (11) are connected to the supports (12A), (12B) of the arc tube which also serves as a conductive wire, and the supports (12A), (12B) penetrate the stem (4) in an airtight manner. It is connected to the base (5) via a lead wire. The one support (12A) installed parallel to the arc tube (6) is covered with an insulator sleeve (13).

In the reflection type metal halide lamp having such a structure, even when the metal reflection film (3) is irradiated with the light emitted from the arc tube (6) at the time of lighting and the photoelectrons are emitted from the metal forming the reflection film, the metal reflection film is generated. Since the film (3) is formed on the outer surface of the outer tube (1), photoelectrons do not reach the arc tube (6) housed in the outer tube (1). Therefore,
There is no loss of sodium to the outside of the arc tube (6) due to photoelectrons, and it is possible to prevent a decrease in lamp efficiency and an increase in lamp voltage due to an increase in excess free halogen → shortening of the lamp life. That is, the result of comparing the lamp voltage of the reflection type metal halide lamp of the above-mentioned example and a general metal halide lamp not provided with a metal reflection film is that the lamp voltage increase value is about 3 V at 1000 hours of lighting, and the effect is the same. It was remarkable.

If the outer surface of the metal reflection film (3) is coated with a heat-resistant and translucent resin such as a fluororesin, it is effective in preventing damage to the metal reflection film (3), and further the metal reflection film (3) is prevented. By covering the entire outer surface of the outer tube (1) including not only the film (3) but also the front light-transmitting part (2) with the above resin, the outer tube glass is prevented from being damaged by the deposition of water drops during outdoor use. It is more preferable because it can.

〔The invention's effect〕

As described above, according to the configuration of the present invention, in the reflective metal halide lamp, the visible light-reflecting metal reflective film that emits photoelectrons when receiving ultraviolet rays is provided on the outer surface of the outer tube. Despite this, it is possible to prevent the loss of sodium outside the arc tube caused by the adhesion of photoelectrons emitted from the metal reflective film to the arc tube, and to prevent the shortening of the life due to the decrease in lamp efficiency and the increase in lamp voltage. You can

[Brief description of drawings]

 The figure shows a schematic diagram for explaining an embodiment of the present invention. (1) ... Outer tube, (3) ... Metal reflection, (6) ... Arc tube, (7) ... Arc tube bulb (8) ... Sealing part, (9) ... Electrode.

Claims (1)

[Claims] 1. An arc tube made of quartz glass in which a pair of electrodes, a rare gas for starting, mercury and at least sodium halide as a metal halide are enclosed; and an inert gas and an arc tube. A reflective metal halide lamp, comprising: an outer tube housed therein; and a metal reflective film provided on the outer surface of the outer tube and capable of emitting a photoelectron when receiving an ultraviolet ray.