JP2668434B2 - Metal halide lamp - Google Patents

Description

[Detailed Description of the Invention] [Object of the invention] The present invention relates to a metal halide lamp having a single sealed airtight container for forming an arc spot on an electrode coil.

(Prior Art) (Industrial Application Field) Since metal halide lamps have excellent luminous efficiency and / or color rendering properties, they are recently being used for lighting fixtures for low ceilings in stores and the like. In addition, since lighting fixtures in stores and the like are required to be miniaturized, miniaturization of metal halide lamps is also required.

However, when trying to reduce the size by adopting a double-sealed hermetic container structure that has been generally adopted in the past, not only is molding time and labor necessary, but also the pinch seal portion becomes large with respect to the discharge space volume. Cannot be downsized. In addition, since the pinch seal portion becomes large, heat dissipation increases, and the coldest portion cannot be maintained at a temperature at which the halide emits light as desired. Thus, there is a problem that it is difficult to obtain desired efficiency and / or color rendering.

In order to meet the demands for downsizing and improvement of luminous efficiency and / or color rendering, a metal halide lamp having a single-sealed hermetic container as described in JP-A-63-148530 (conventional lamp 1). Is proposed.

This is a single-sealed quartz glass hermetic container having a pinch seal portion at one end, a discharge medium containing a metal halide sealed in the hermetic container, and a single sealing surface of the pinch seal portion. A pair of metal foils juxtaposed and spaced apart,
A base end portion is connected to one end of a corresponding metal foil, an electrode shaft made of a pair of tungsten (W) introduced into an airtight container, and a trier disposed so as to face each other at the tip end portions of these electrode shafts. Made of Ted Tungsten,
A pair of electrode assemblies having a pin-shaped electrode main body for increasing heat capacity, and a pair of external conductors connected at one end near the other end of the corresponding metal foil and led out from the airtight container. ing.

With this configuration, since there is only one pinch seal portion, heat loss is reduced as compared with a hermetically sealed airtight container, and luminous efficiency and / or color rendering can be improved. And the number of pinch seal portions that tend to be relatively large compared to the size of the discharge space is reduced to one, so that the overall structure of the airtight container can be reduced in size.

(Problems to be solved by the invention) In order to increase the luminous efficiency, the lamp input power must be set to WL.
(W), when the inner wall surface of the airtight container is set to S (cm2), the temperature of the airtight container rises when the conventional lamp 1 is lit with a high load of 20 to 70 for the wall load WL / S. .

In the conventional lamp 1 having the single-sealed hermetic container, the arc is located at a substantially right angle with respect to the linear portion implanted in the hermetic container of the electrode axis. As a result, the temperature rise of the electrode shaft becomes remarkable. When the temperature of the electrode shaft becomes high, reaction with halogen easily occurs during its life, so the electrode shaft becomes thin, the electrode shaft material scatters on the inner surface of the airtight container, blackening occurs, and the luminous flux maintenance factor decreases and The shaft breaks.

Further, since the arc spot is formed on the pin-shaped electrode main body portion provided at the tip of the electrode shaft, the arc spot is fixed, so the electrode material of the portion where the arc spot is formed during the life Are scattered, and the arc gap between the electrode main portions changes, so that the luminous efficiency fluctuates.

Further, in the conventional lamp 1, since the heat capacity becomes large when the electrode main body is too large, the temperature rise of the electrode main body is slowed at the time of starting, the stability of the arc is poor, and the starting performance cannot be performed well.

Furthermore, since the electrode shafts are arranged in parallel because of the single sealed airtight container, if the distance between the electrode main parts is not much different from the distance between the electrode shafts, there is a problem that the discharge between the electrode shafts occurs. There is.

Therefore, by adopting a structure in which the arc spot is formed on the electrode coil, the arc gap between the electrode main parts is less likely to change, and the distance between the electrode axes is increased compared to the distance between the electrode main parts. It is necessary to make the heat capacity of the electrode main body proper.

An object of the present invention is to increase the inter-electrode-axis distance as compared with the inter-electrode-coil distance, while optimizing the heat capacity of the electrode-axis tip portion, thereby suppressing the inter-electrode-axis discharge and the deterioration of the startability, It is an object of the present invention to provide a metal halide lamp that has a long service life and can meet the demand for miniaturization.

[Means for Solving the Problems] (Means for Solving the Problems) A metal halide lamp according to claim 1 is a hermetically sealed airtight container having a pinch seal part at one end; and a single sealing surface of the seal part. A pair of metal foils that are spaced apart and juxtaposed; a pair of electrode shafts that are planted in an airtight container with their base ends connected to the vicinity of one end of the corresponding metal foils, and bent so that their tips face each other And wound around each electrode shaft from the base of the bent portion of the electrode shaft beyond the tip of the electrode shaft,
It consists of a pair of electrode coils in which an arc spot is formed at the time of lighting, the electrode coil is made of a material having a higher melting point than the material constituting at least the surface portion of the electrode shaft, and at least the surface portion of the electrode shaft has high halogen resistance. The length from the base of the bent portion of the electrode shaft to the tip of the electrode shaft is L1, the length of the wound coil portion of the electrode coil is L2, and the wire diameter of the coil wire is When d, a pair of electrode structures configured to satisfy d ≦ L1 ≦ 3d d / 2 ≦ L2-L1 ≦ 3d; a discharge medium containing a metal halide enclosed in an airtight container; A light emitting tube consisting of a pair of outer conductors connected to the vicinity of the other end of each metal foil and led out from the airtight container; an outer tube surrounding the light emitting tube; Structured to operate at loads between 20 and 70 W / cm2 It is.

The metal halide lamp according to claim 2 is the metal halide lamp according to claim 1, wherein at least the surface of the electrode shaft is formed of pure rhenium metal or rhenium-tungsten alloy.

As long as the melting point of the electrode shaft is lower than that of the electrode coil, a known material can be used.

(Operation) According to the first aspect of the present invention, since the tube wall load is operated at 20 to 70 W / cm2 at the time of lighting with the single sealed airtight container,
Since the heat from the arc easily hits the electrode shaft, the temperature of the electrode shaft becomes high. When the electrode shaft becomes hot, it reacts with the halogen in the airtight container and the electrode is likely to become thin, but at least the surface part of the electrode shaft is made of a halogen-resistant material. Since it is difficult to react, breakage of the electrode shaft is suppressed.

Further, since d ≦ L1, at least one or more turns of the electrode coil are disposed at the bent end of the electrode shaft, and the electrode coil is firmly fixed to the electrode shaft. Further, since d / 2 ≦ L2−L1, the bent tip of the electrode shaft is drawn at least d / 2 from the discharge space side from the tip of the electrode coil, and the tip of the electrode shaft having a low melting point. It is possible to prevent an arc spot from being generated. Furthermore, since L1 ≦ 3d, the size of the electrode coil is restricted, the electrode coil does not become excessive, and the electrode coil is partially hollow, so the heat capacity at the tip of the electrode shaft is not too large. I won't. In addition, since L2−L1 ≦ 3d, the size of the protrusion from the tip of the electrode shaft is restricted, and the distance between the electrodes is maintained at a predetermined size even in a small discharge space.

Furthermore, since the material constituting at least the surface portion of the electrode shaft has a lower melting point than the electrode coil, it is easy to join the pinch seal portion to the metal foil.

 According to claim 2, the operation of claim 1 is performed.

(Embodiment) FIG. 1 is a front sectional view of an embodiment of the present invention, and FIG. 2 is a partial sectional view showing a main part of the embodiment.

This example shows a metal halide lamp with a lamp input power of 150W.

Reference numeral 1 denotes an outer tube made of quartz glass, which houses an airtight container 2.

The outer tube 1 has a pinch seal portion 1a formed only at one end, and a metal foil 6, such as Mo,
6 is sealed. These metal foils 6, 6 have external lead wires 7,
7 is connected, and the internal lead wires 5, 5 also serving as support are connected. These internal lead wires
5 and 5 also serve as external lead wires of the airtight container 2.

A base (not shown) is attached to the pinch seal portion 1a of the outer tube 1.

The hermetic container 2 has a single-sealed shape similarly to the outer tube 1, and is formed of quartz glass. This airtight container 2
Has a substantially elliptical spherical discharge space with an internal volume of 0.5 cc. Such a elliptical spherical discharge space has a tube axis in the major axis direction and a pinch seal part at one end in the minor axis direction orthogonal to this tube axis. 2a is formed.

In the airtight container 2, a pair of electrodes 3, 3 are arranged facing each other in the tube axial direction with a space therebetween, and both electrodes 3, 3 are made of Mo or the like sealed in the pinch seal portion 2a on one side. Such metal foils 4, 4 are respectively connected. The internal lead wires 5,5 also serving as supports for the outer tube 1 are connected to the metal foils 4,4, respectively.

As shown in FIG. 2, the electrodes 3, 3 are composed of an electrode shaft 8 and an electrode coil 9 wound therearound.

The electrode shaft 8 is pure rhenium or rhenium with a wire diameter of 0.5 mm.
It is formed of a tungsten alloy wire or a tungsten wire coated with pure rhenium or a rhenium-tungsten alloy, and has a base end connected to the metal foil 4 of the pinch seal portion 2a and a tip end formed. ,
A bent tip 8a is formed so that the electrodes 3, 3 face each other.

The electrode coil 9 is formed by winding a coil having a wire diameter of 0.5 mm or tungsten (containing about 20% of ThO2) in a coil shape, for example, having about 3 to 4 turns.

Such an electrode coil 9 is wound from the bent front end 8a of the electrode shaft 8, that is, the base 8b of the bent portion of the electrode shaft 8, beyond the front end of the electrode shaft 8. In this case, when the length of the bent tip 8a of the electrode shaft 8 is L1, the length of the wound coil portion of the electrode coil 9 is L2, and the wire diameter of the coil wire is d, d ≦ L1 ≦ 3d (1) d / 2 ≦ L2−L1 ≦ 3d (2)

In this embodiment, the wire diameter d of the coil wire is 0.5 mm,
The length L1 of the bent front end portion 8a is 1.0 mm, and the length L2 of the wound coil portion is 1.5 mm.

The axial dimension between the electrode coils 9, 9 facing each other, that is, the distance between the electrodes is set to 6.8 mm.

Further, the distance between the base ends of the electrode shafts 8, 8 is larger than the distance between the electrodes.

The outer tube 1 is filled with, for example, a starting rare gas, a predetermined amount of mercury, and a metal halide such as SnI2, NaI, TlI, InI, NaBr, and LiBr.

In this embodiment, the lamp current I during stable lighting is 1.
At 8 A, the lamp input power W at this time is set to be 150 W.

The inner surface area S of the hermetic container is 3.5 cm2, and the lamp load per unit surface area of the hermetic container is about 43 W / cm2.

[Effect of the Invention] According to claim 1, since at least the surface of the electrode shaft is made of a halogen-resistant material, a single-sealed hermetic container is provided, and the tube wall load is reduced during lighting. 20 to 70 W / cm2
, The temperature of the electrode shaft becomes high, but since the electrode shaft does not easily react with halogen, breakage of the electrode shaft portion is suppressed.

Further, since d ≦ L1, at least one or more turns of the electrode coil are disposed at the bent end of the electrode shaft, and the electrode coil is firmly fixed to the electrode shaft. Furthermore, since d / 2 ≦ L2−L1, an arc spot is prevented from being generated at the tip of the electrode shaft having a low melting point,
A decrease in the luminous flux maintenance ratio due to blackening of the tube wall due to scattering of the electrode shaft is prevented. Furthermore, since L1 ≦ 3d, the electrode coil does not become excessively large, the electrode coil becomes partially hollow, and the heat capacity at the tip of the electrode shaft does not become excessive, so that the startability does not decrease. Also, L2-L1 ≤
Since the distance is set to 3d, the distance between the electrodes is secured to a predetermined size, and the discharge is stabilized.

Further, since the material forming at least the surface portion of the electrode shaft has a lower melting point than the electrode coil, the pinch seal portion can be easily joined to the metal foil, so that it is possible to meet the demand for downsizing with a long life. We can provide metal halide lamps.

 According to Claim 2, the effect of Claim 1 is produced.

[Brief description of the drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a front sectional view,
FIG. 2 is a partial sectional view showing a main part. DESCRIPTION OF SYMBOLS 1 ... Outer tube, 2 ... Airtight container, 2a ... Pinch seal part, 3 ... Electrode assembly, 4 ... Metal foil, 8 ... Electrode shaft, 9 ... Electrode coil.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisanori Sano 1-1201 Funakoshi-cho, Yokosuka-shi, Kanagawa 1 Inside Yokosuka Plant, Toshiba Corporation (56) References JP-A-63-24539 (JP, A) JP-A Sho 63-148530 (JP, A) JP-A-62-37862 (JP, A) JP-A-61-32345 (JP, A) JP-A-59-75554 (JP, A)

Claims (2)

(57) [Claims] 1. A single-sealed airtight container having a pinch seal portion at one end; a pair of metal foils spaced apart from each other on a single sealing surface of the seal portion; A pair of electrode shafts, which are implanted in an airtight container in a state of being connected near one end of the metal foil to be bent, and whose tips are bent so as to face each other, and the electrodes from the base of the bent portion of the electrode shaft to each electrode shaft It consists of a pair of electrode coils wound beyond the tip of the shaft and forming an arc spot when lit. The electrode coil is made of a material having a higher melting point than the material forming at least the surface of the electrode shaft. At least the surface is made of a material with high halogen resistance, and the length from the base of the bent portion of the electrode shaft to the tip of the electrode shaft is L1, and the length of the coil portion around which the electrode coil is wound is L1. L2, coil wire diameter When d, a pair of electrode structures configured to satisfy d ≦ L1 ≦ 3d d / 2 ≦ L2-L1 ≦ 3d; a discharge medium containing a metal halide enclosed in an airtight container; An arc tube consisting of a pair of outer conductors connected to the vicinity of the other end of each metal foil and led out of the airtight container; an outer tube surrounding the arc tube; Metal halide lamps configured to operate at a load of 20 to 70 W / cm2. 2. The metal halide lamp according to claim 1, wherein at least the surface of the electrode shaft is formed of pure rhenium metal or a rhenium-tungsten alloy.