JPS62157662A - High pressure discharge lamp - Google Patents

Abstract

PURPOSE:To prevent cracks generated on a metallic foil provided on the sealing portion of an airtight vessel in the captioned lamp, by providing a flexible portion which is not welded to a quartz glass in sealing portions, in the vicinity of the connecting portion to an electrode. CONSTITUTION:On both sealing portions of an airtight vessel 1 made of a quartz glass, a pair of electrode base portions opposed to each other are sealed via a sealing metallic foil, thus a high pressure discharge lamp such as a xenon lamp is formed. When a small diameter portion of the base portion 4a of an electrode 4 is connected to an outside introducing body 7 through a quartz body 6, inside of the quartz glass 3a in the sealing portion, a sealing metallic foil 5, having a flexible portion 5a which is not welded to the quartz glass 3a in the vicinity of the connecting portion B, is employed. And, expansion force applied to the metallic foil 5 by expansion and construction generated on the electrode 4 during flashing can be absorbed. Therefore, it is possible to prevent the breakage of the metallic foil 5 without enlarging the size of the lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high pressure discharge lamp in which the sealing part 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, while short-arc lamps used for special purposes such as high-pressure mercury lamps used for general lighting, xenon lamps, and ultra-high-pressure mercury lamps use quartz electrodes. The end of an airtight container made of 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 property with the quartz glass.

In such lamps, especially when the lamp is used frequently with flashing, the repeated expansion and contraction of the electrodes can cause
The metal foil connected to the electrode similarly expands and contracts,
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 north pole than its cathode side or an AC-lit lamp, so the incidence of the above-mentioned accidents was high. The causes of such accidents will be explained with reference to FIG. 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). (4
) is an anode, which is welded and connected to sealing metal foils (5), (5) made of molybdenum via platinum at position B. In the case of this example, two metal foils (5) are used, and a quartz body (6) called separator glass is sandwiched between them, and the metal foils (5) are hermetically sealed to the sealing portion (3A). (The force is connected to the other end of the metal foil (51, (51) by the external introduction body. Generally, the sealing is completed by sealing the quartz glass (3a) of the sealing part (3A) and the metal foil (5). The anode (4) is hermetically sealed to the
) to the metal foil (5) at position A, which is a little away from the point where the metal foil (5) is transferred. This is because the shaft diameter of the anode (4) is large, and the anode (4) cannot be brought into close contact with the quartz glass in a completely airtight manner at that part, and a slight gap is created up to the position A, which is a little further away. Therefore, the metal foil (5) is connected from point A to the anode (
4) There is a slight gap between the glass and the quartz glass toward the side, so there is a blue discoloration caused by stretching or shrinkage. In addition, since the anode (4) and the metal foil (5) are welded at the above point B, the metal foil (5) is subject to expansion and contraction force in the portion between A and B as the anode (4) expands and contracts. I will be joining. As a result, it was found that mechanical fatigue caused cracks in the metal foil (5) mainly at point A, which gradually progressed and eventually broke, rendering the lamp defective.

In addition, a method for preventing the sealing metal foil from being cut due to tension in the sealing part of a quartz glass tube was disclosed in Japanese Utility Model Publication No. 47-400.
This is shown in Publication No. 93. Figure 4 shows an example of this, in which an electrode (4) is welded to the end of an airtight container (1) made of quartz glass, and a metal foil for sealing, which will be described later, is attached to the outside. An airtight chamber aυ is provided for this purpose, and the airtight chamber αυ is filled with a vacuum or an inert gas. The electrode (4) is connected to the external introduction body (force) through an intermediate body (6) made of quartz glass along the tube axis, and the welded part between the electrode (4) and the airtight container (1) is ), and is hermetically sealed to the quartz glass of the airtight container (1) via a sealing metal foil (5) made of, for example, molybdenum, which is welded to the pole (4) and the external introduction member (force). The sealing metal foil (
5) is extended into the airtight container (1) leaving a bent part (5b), and the extended part (5C) connects the intermediate body (6) and the metal foil (5) at a position where it contacts the intermediate body (6)K. ) and airtight container (1)
and are welded together. Further, at the position of the external introducing body (7), another metal foil a9 wound around the outside of the extension part (5c) of the metal foil (5) is in contact with the airtight container (1), so the metal foil (5) slides freely along the pulp axis, and the bent part (5b) absorbs the tension on the metal foil (5), so cutting of the metal foil (5) can be prevented. Are listed. However, the strong tension exerted on the metal foil K in question in this case is due to the fact that the metal foil is melt-sealed into the pulp while being stretched in the axial direction during the manufacturing of the tube, that is, when the sealing part is heated and formed, and during the cooling process. This refers to the tension that occurs when the metal foil that is fixed at both ends shrinks, and is different from the tension that is applied to the metal foil when the lamp is turned on, which is the object of the present invention. Moreover, the method described in the above publication further provides an airtight chamber αυ outside the sealed portion of the airtight container (1), and positions the bent portion (5b) of the metal foil (5) within this airtight chamber I. Therefore, the total length of the lamp becomes long, making it unsuitable for the generally desired miniaturization of the lamp.Furthermore, when assembling the lamp, as shown in Figure 4 of the publication, a plurality of metal foils for bending (5 ), In addition to (5), there is also the disadvantage that a separate metal foil (I) is required, which requires time and effort, and increases cost.

[Purpose of the invention]

The present invention has been made to address the above drawbacks.

To provide a high-pressure discharge lamp which is the same in size as a conventional one and can prevent a metal foil for sealing from breaking despite having a simple structure.

[Summary of the invention]

In the present invention, a pair of electrodes is provided oppositely by sealing the proximal end portions to both end sealing portions of an airtight container made of quartz glass.

Each of the above electrodes is connected to the external introduction body through a sealing metal foil, and the sealing metal foil on at least one electrode side has a
This is a high-pressure discharge lamp in which a bent portion that is not fused to the quartz glass sealing portion is provided on the side of the external introduction body near the connection portion with the electrode.

[Embodiments of the invention]

Hereinafter, two embodiments of the present invention will be described with reference to the drawings.

Figure 1 is a longitudinal cross-sectional view of a 350W class xenon lamp.

FIG. 2 shows a longitudinal sectional view of the anode side sealing portion. (1) is an airtight container with a quartz glass surface in which xenon gas is sealed, and consists of an elliptical sphere-shaped main body (2) surrounding a discharge space and sealing parts (3A) and (3B) extending on both sides of the main body (2). (
4) is an anode made of a tungsten rod with a diameter of about 5n, and its base end (4a) is sealed to one of the sealing parts (3A). (
5) and (5) are metal foils for sealing made of a high-melting point metal such as molybdenum, and are arranged by sandwiching a quartz body (6) called separator glass, and one end of each is at position B. It is connected to the tip side thin wall part (4C) of the anode base end part (4a) through platinum (not shown), and the other end is connected to the external introduction body (force) through platinum. (51 is completely hermetically sealed with the quartz glass (3a) of the sealing part (3A) from the anode (4) to the sealing metal foil (5),
This is the part to the right of position A, which is a little distance from the transition to (5), that is, toward the external introduction body (7) side. The sealing portion B is connected to the quartz glass (3a) and the sealing metal foil portion that is not fused, that is, the anode (4).

In addition, (8) is a cathode consisting of a thin tungsten rod with a diameter of about 2 cages, and its base end (8a) is sealed to the other sealing part (3B) in the same way as the anode (4) side. (6) is connected to the other external introduction body (9) via sealing metal foils (5A) and (5A) placed between them.

In a xenon lamp with such a configuration, the electrodes, especially the large anode (4), expand more than the cathode (8) during one blink.

Contraction occurs, and as a result, expansion and contraction force is also applied to the sealing metal foils (5), (5) connected to the anode (4).
The metal foil for sealing (5), (5) has a bent portion that is not fused to the sealing portion quartz glass (3a) on the external introduction body (7) side near the connection portion B with the anode (4). (5a) is provided, and since this bending portion (5a) absorbs the stretching force, it is highly effective in preventing foil breakage.

Such an example lamp has a lamp current of 17.5A and a
I conducted a flashing test with a cycle of 5 minutes on and 5 minutes off.
Metal foil for sealing (5) even after 10,000 times.

(5) showed no signs of foil breakage. On the other hand, the metal foil for sealing (5), (5) has a bent part (5a).
, 1,00 for conventional lamps without (5a)
In some cases, minute foil breakage was already observed after about 0 cycles.

Although the explanation so far has been made regarding the anode (4) side, this is because the structure described above is generally particularly large in a DC lighting type lamp like the one in this embodiment.

In addition, it is effective on the anode (4) side, where the temperature is higher than the cathode (8) side, and there is less risk of the sealing metal foil (5A) breaking on the cathode (8) side. Although it is not necessary to provide the bent portion (5a), as the lamp capacity increases, the current also increases on the cathode side and the temperature becomes higher.

This increases the risk of the metal foil for sealing breaking.
It is preferable to provide a bent portion (5a) similarly to the anode side. In addition, even in AC lamps with a large capacity, both electrodes alternately act as anodes every half cycle and reach a considerable temperature, so the metal foil for sealing on both electrodes is bent. Preferably, a bent portion is provided.

In the above embodiment, the metal foil for sealing (5) was arranged so as to sandwich the quartz body (6) called separator glass, but even if the lamp does not use the quartz body (6), The present invention is effective.

Further, similar effects can be obtained with other high-pressure discharge lamps other than xenon lamps, such as high-pressure mercury lamps and ultra-high-pressure mercury lamps.

〔Effect of the invention〕

As described in detail above, according to the present invention, the sealing part quartz is provided on the external introduction body side near the connection part with the electrode of at least one (higher temperature) electrode side sealing metal foil of the high pressure discharge lamp. By simply providing a bent portion that does not fuse with the glass, it is possible to prevent the sealing metal foil from breaking due to expansion and contraction of the electrodes, without increasing the size of the lamp as in conventional lamps.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a xenon lamp which is an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of the anode side sealing part which is the main part, and Fig. 3 is a longitudinal sectional view of the anode of a conventional xenon lamp. A longitudinal sectional view of the side sealing portion, and FIG. 4 shows a longitudinal sectional view of the one end sealing portion of a different conventional lamp. (1)...Airtight container, (3A),
(3B)...Sealing part. (3a)...Sealing portion quartz glass. (4)... Anode, (4a)...
...anode base end. (5), (sA)...Metal foil for sealing. (5a)...Bending portion, (7), (9)
・・・・・・External introduction line. (8)...Cathode.

Claims (1)

[Claims] A high-pressure discharge lamp comprising a pair of electrodes each sealed at both ends of a quartz glass airtight container with the base end sealed, and each of the electrodes connected to an external introduction member via a metal foil for sealing. The metal foil for sealing on at least one of the electrodes is provided with a bent portion that is not fused to the silica glass sealing portion on the side of the external introduction body near the connection portion with the electrode. High pressure discharge lamp.