JPS62115644A - high pressure discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high-pressure discharge lamp in which the electrode sealing portion of an airtight container such as a quartz arc tube is improved.

[Technical background of the invention and its problems]

In general, high-pressure discharge lamps use thick and large electrodes made of high-melting-point metals such as tungsten. The end of an airtight container made of silica glass is sealed with a metal foil made of a high melting point metal such as molybdenum interposed therebetween. The anode side of DC-lit lamps and large-capacity AC-lit lamps are equipped with electrodes that are enlarged to match the current consumption, but the sealing metal foil connected to these electrodes is Although the width is increased, the thickness is extremely thin, with a maximum value of about 20 to 35 μm, in order to improve the sealing properties with the quartz glass.

In such a lamp, especially when the lamp is used in a frequently flashing state, due to the repeated expansion and contraction of the IIR electrode, the metal foil connected to the electrode also expands and contracts repeatedly.
As a result, extremely thin metal foils may break during use, resulting in non-lighting. In particular, the anode side of a DC-lit lamp consumes more power at the electrode than its cathode side or an AC-lit lamp, and the incidence of the above-mentioned accidents was high. The cause of such accidents will be explained with reference to the third cause. The figure shows a longitudinal cross-sectional view of the anode-side sealing part of a xenon lamp, which is a DC lamp. In the figure, (1) is an airtight container made of quartz glass, the end of which is heated and deformed to form a sealing part (3A). (8
) is an anode, which is connected at position B by welding to a sealing gold foil (6A) made of molybdenum via platinum.

In the case of this example, two metal foils (6A) are used, and a quartz body (5) called separator glass is sandwiched between them, and the metal foils (6A) are hermetically sealed to the sealing part (3A). (7A) is an externally introduced substance, and is it the above metal? ? 3 (6A) and the other end of (6A). Generally, the sealing part (3A) of the quartz glass and the metal foil (6A) are completely hermetically sealed between the anode (8) and the metal foil (6A).
This is the position of

This is because the shaft diameter of the anode (8) is large, and it cannot be completely airtightly adhered to the quartz glass at that part, and a slight gap αQ will occur from point A to point t. . Therefore, the metal foil (6A) is connected from point A to the anode (
8) There is a slight gap between the quartz glass and the side (10)
Because of this, there is a property that can be pulled or contracted. Also, since the anode (8) and the metal foil (6A) are connected at the above point B, as the anode (8) expands and contracts, the metal foil portion between A and B An elastic force will also be added to it. As a result, mechanical fatigue causes cracks in the metal foil (6A) mainly at point A, which gradually progresses and eventually breaks, resulting in a defect 8 in the lamp. This process was the result of 9 repeated flashing tests by the inventors and continued close observation of the lamp.

, it is something that was created.

[Purpose of the invention]

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional lamps, and an object of the present invention is to provide a high-pressure discharge lamp that is free from defects caused by cutting of the sealing metal foil.

[Summary of the invention]

The present invention forms a thin part at the base end of a large electrode that is sealed in the sealing part of a quartz glass airtight container, and the thin part is thicker at the tip end. It is characterized by forming a gradient, so even if the electrode expands or contracts when the lamp flashes, it will not work! This is because the tip side of the thin section provided at the base end of the pole is thick.

The expansion and contraction of the thick tip side is relaxed, and the force applied to the metal foil is also weakened, thereby preventing the foil from breaking.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows a 500W class xenon lamp, in which (1) is an airtight container made of quartz glass with xenon gas sealed inside, an elliptical sphere-shaped main body (2) that surrounds the discharge space, and seals that extend on both sides of the main body (2). It consists of parts (3A) and (3B). (
4) is a cathode with a diameter of about 3 mm, its base end (4a) is sealed with a sealing part (3B) K, and a quartz body (5) called separator glass is sandwiched between two sheets made of molybdenum, for example. It is connected to the external introduction body (7B) via sealing metal foils (6B) and (613). (8) is an anode with a diameter of about 6 mm, and its base end (8a) is sealed to the other sealing part (3A), as shown enlarged in FIG.

A substantially flat thin part (9) with a length l of 7 TrrA is formed at the proximal end (8a), and as seen from the thickness direction as shown in Figure 9, the point a is the tip part ( At point b on the 9a) side, a slope is formed so that the thickness is 2.5n, forming a wedge shape. (6A) and (6A) are each 5m wide
A quartz body (5) called separator glass is sandwiched between sealing metal foil made of, for example, molybdenum, which is extremely thin and has a maximum thickness of 26 μm, as on the cathode (4) side.
One end is connected to the anode (8) via platinum (not shown), and the other end is connected to the external introduction body (7A). (Note that the first drawing is shown in a slightly exaggerated manner for convenience of explanation.) The xenon lamp having such a configuration is different from conventional lamps in the vicinity of the contact area between the quartz body (5), which is the separator glass, and the anode (8). Similarly, a slight gap is created between the sealing part (3A) and the quartz glass, causing tension and contraction, but when the lamp flashes, the anode (8) expands and contracts.
Even if shrinkage occurs, the thin wall portion (9) on the base end side of the anode is shaped in the thickness direction so that the tip end (9a) side thereof is thicker. The metal foils (6A) and (6A) are wedged into the quartz glass of the stopper (3A), and their expansion and contraction are relaxed, so that the expansion and contraction force applied to the metal foils (6A) and (6A) is also weakened.

Foil breakage due to mechanical fatigue can be prevented.

Next, in a conventional lamp, that is, if the thickness of the thin part (9) formed at the base end of the anode is constant, and referring to FIG. 2, a =
As a result of repeated comparisons of blinking tests (5 minutes on - 5 minutes off) for each of the above example lamps with b = 2 and l = 7, this example lamp was tested 3,000 times. Even after repeated flashing, there were no abnormalities in all cases, but with the conventional lamp, there were three foil breakage defects: one at 1,200 flashes, one at 1,500, one at 2,200, and one at 3,000. , even though the remaining two pieces are not completely cut out,
Abnormalities indicating signs of foil breakage were observed in some parts.

By the way, the degree of inclination of the wedge shape of the anode thin wall portion (9) is in the example (Coley), but this value is in the range 2A of 115 to 115o.
! 50 is preferable; if it is larger than 115, the above-mentioned slope becomes too steep and stress concentration becomes large, resulting in negative effects such as a decrease in pressure resistance.
The smaller the foil breakage prevention IJ, the less effective it is.

Manufacturing variations. In particular, the gap (11
The above effect also varies due to the variation in the amount of foil, and as a result, there may be cases where the lamp shows signs of foil breakage due to repeated blinking of the lamp.

In addition, as in the above embodiment, in a DC-lit lamp, this is particularly effective on the anode side, where the temperature is high, but even on the cathode side, as the current increases, the expansion of the cathode,
If the foil is cut based on shrinkage, it cannot be ignored, so Il#I
It is preferable to have the same structure as the electrode side, and even in a large-capacity AC lighting type lamp, each electrode acts as an anode every half cycle and reaches a considerable temperature.

It is preferable that both electrodes have the same configuration as the anode side in the above embodiment. Furthermore, in the above embodiment, the thin part (9) was formed by making the base end of the electrode substantially flat, but a thin part (9) with a circular cross section was formed by narrowing the base end of the round rod-shaped electrode as it was, and the tip of the thin part (9) was formed by making the base end of the electrode substantially flat. If the part is a circular shape with a large diameter and viewed from the threading direction, Kv! ! ! There are two possible variations, such as a different shape.

Furthermore, the present invention is equally effective for xenon lamps that do not use separator glass, and is not limited to xenon lamps, but can also be applied to other high-pressure discharge lamps such as high-pressure mercury lamps and ultra-high-pressure mercury lamps. It is something.

〔Effect of the invention〕

As described in detail above, according to the present invention, the electrodes generated during blinking of the high-pressure discharge lamp reach a high temperature [cutting due to expansion and contraction of the sealing metal foil connected to the other side].

It is possible to prevent defects and obtain a rung with high reliability and long life.

[Brief explanation of drawings]

1 and 2 show a xenon lamp which is an embodiment of the present invention, FIG. 1 is a longitudinal sectional view of the entire lamp, FIG. 2 is a longitudinal sectional view of the anode side sealing part, which is the main part, FIG. 3 shows a vertical cross-sectional view of the sealing portion on the anode side of a conventional xenon lamp. (1)...Airtight container. (3A), (3B)...Sealing part of airtight container. (4)...Cathode, (4a)...
...The base end of the cathode. (6A), (6B)...Metal foil. (8)... Anode, (8a)...
...Proximal end of the anode.

Claims (1)

[Claims] In a high-pressure discharge lamp, a pair of electrodes is provided oppositely by sealing the proximal ends to both end sealing parts of an airtight container made of quartz glass, and the electrodes are connected to an external introduction body through a metal foil for sealing. A high-pressure discharge lamp, characterized in that at least one of the electrodes has a thin part formed at its base end, and the thin part has a slope such that it becomes thicker toward the tip end.