CN108807134A - Discharge lamp - Google Patents

Abstract

The present invention provides a discharge lamp capable of improving luminous efficiency, suppressing rise in tube voltage, prolonging life, and irradiating light of a desired color even if it is lit with low power. It includes: a light-emitting part having a discharge space in which a discharge medium is sealed, the discharge medium contains metal halides and inert gases, and substantially does not contain mercury; and a pair of electrodes protrudes into the discharge space and separates Arranged facing each other at a predetermined distance. The metal halides include scandium halides, sodium halides, indium halides, and zinc halides. When the weight of the scandium halide is Ms and the weight of the sodium halide is Mn, 0.8≦Mn/Ms≦1.3. The weight ratio of the indium halide to the metal halide is 0.3 wt% or more and 2.0 wt% or less.

Description

discharge lamp

technical field

Embodiments of the present invention relate to a discharge lamp.

Background technique

There is a discharge lamp including: a light emitting unit having a discharge space in which a discharge medium is sealed; and a pair of electrodes protruding into the discharge space and arranged facing each other with a predetermined distance therebetween.

Conventionally, the discharge medium includes metal halides, inert gases, and mercury. However, in recent years, from the viewpoint of environmental protection, mercury is not contained in the discharge medium.

In addition, in accordance with the demand for power saving, for example, a discharge lamp is required to be lit with electric power of 22 W (Watt) or more and 28 W (Watt) or less during stable lighting. However, when the discharge lamp is turned on with power of 28W (watt) or less, the temperature of the light emitting part is lower than when the discharge lamp is turned on with power of about 35W (watt). Therefore, there is a problem that the luminous efficiency of a discharge lamp lit with power of 28 W (watt) or less is lower than that of a discharge lamp lit with power of about 35 W (watt).

In such a case, the luminous efficiency can be improved by adjusting the composition ratio of the metal halide. For example, the luminous efficiency can be improved by increasing the ratio of the scandium halide contained in the metal halide. However, simply increasing the ratio of the halide of scandium contained in the metal halide increases the tube voltage and easily causes flicker.

In addition, depending on the composition ratio of metal halides, free iodine may increase to cause so-called foil leaks, resulting in shortened lifespan or a color that does not fall within a desired range.

Therefore, it is desired to develop a discharge lamp capable of improving luminous efficiency, suppressing a rise in tube voltage, prolonging life, and emitting light of a desired color even when lit with low power.

prior art literature

patent documents

Patent Document 1 Japanese Patent Application Publication No. 2013-511117

Contents of the invention

The problem to be solved by the invention

The problem to be solved by the present invention is to provide a discharge lamp capable of improving luminous efficiency, suppressing rise in tube voltage, prolonging life, and emitting light of a desired color even when lit with low power.

technical means to solve problems

The discharge lamp of the embodiment can be lit with electric power of 22W (Watt) or more and 28W (Watt) or less when it is turned on stably. The discharge lamp includes: a light-emitting portion having a discharge space sealed therein with a discharge medium containing a metal halide and an inert gas and substantially not containing mercury; and a pair of electrodes protruding into the discharge space, And they are arranged facing each other with a predetermined distance apart. The metal halides include scandium halides, sodium halides, indium halides, and zinc halides. When the weight of the scandium halide is Ms and the weight of the sodium halide is Mn, 0.8≦Mn/Ms≦1.3. The weight ratio of the indium halide to the metal halide is 0.3 wt% or more and 2.0 wt% or less.

The effect of the invention

According to the embodiments of the present invention, it is possible to provide a discharge lamp capable of improving luminous efficiency, suppressing a rise in tube voltage, prolonging life, and emitting light of a desired color even when lit with low power.

Description of drawings

FIG. 1 is a schematic diagram for illustrating a discharge lamp of this embodiment.

Explanation of symbols

1: inner tube;

2: metal halide;

3: electrode mounting frame;

4: sleeve;

5: outer tube;

11: Luminous part;

12: sealing part;

13: Boundary;

14: cylindrical part;

31: metal foil;

32: electrode;

33: Coil;

34: lead wire;

35: support line;

61: main body;

71: metal belt;

72: Install accessories;

81: bottom terminal;

82: side terminal;

100: discharge lamp;

101: burner;

102: lamp holder;

111: discharge space.

Detailed ways

Embodiments are illustrated below with reference to the drawings.

The discharge lamp according to the embodiment of the present invention can be, for example, a high-intensity discharge (High Intensity Discharge, HID) lamp used in an automobile headlight. In addition, when the discharge lamp is an HID lamp used in an automobile headlight, it can be a discharge lamp that performs so-called horizontal lighting.

The use of the discharge lamp according to the embodiment of the present invention is not limited to automobile headlights. Here, as an example, a case where the discharge lamp is an HID lamp used in automobile headlights will be described as an example.

FIG. 1 is a schematic diagram illustrating a discharge lamp 100 according to this embodiment.

In addition, in FIG. 1 , when the discharge lamp 100 is mounted on an automobile, the front direction is referred to as the front end side, the rear direction is referred to as the rear end side, and the upward direction is referred to as the upper end side. , let the downward direction be the lower end side.

As shown in FIG. 1 , a burner (burner) 101 and a socket (socket) 102 are provided in a discharge lamp 100 .

The burner 101 is provided with an outer tube 5 , an inner tube 1 , an electrode mount 3 , a support wire 35 , a sleeve 4 and a metal band 71 .

The outer tube 5 is provided on the outer side of the inner tube 1 concentrically with the inner tube 1 . That is, the burner 101 has a double pipe structure formed by the outer pipe 5 and the inner pipe 1 . The outer tube 5 is joined (welded) to the vicinity of the cylindrical portion 14 of the inner tube 1 .

Gas is enclosed in the closed space formed between the inner tube 1 and the outer tube 5 . The gas to be sealed can be a gas capable of dielectric barrier discharge (dielectric barrier discharge). The gas to be sealed can be, for example, one gas selected from neon, argon, xenon, and nitrogen, or a mixed gas of these gases. The gas filling pressure can be set to 0.3 atm at normal temperature (25° C.), for example. In addition, the gas filling pressure is more preferably 0.1 atm or less at normal temperature (25° C.).

The outer tube 5 is preferably formed of a material having a thermal expansion coefficient close to that of the material of the inner tube 1 and having ultraviolet blocking properties. The outer tube 5 can be formed of, for example, quartz glass to which oxides such as titanium, cerium, and aluminum are added.

The inner tube 1 includes a light emitting part 11 , a sealing part 12 , a boundary part 13 and a cylindrical part 14 . The light emitting part 11, the sealing part 12, the boundary part 13, and the cylindrical part 14 can be integrally formed.

The inner tube 1 (the light-emitting part 11, the sealing part 12, the boundary part 13, and the cylindrical part 14) is formed of a material having translucency and heat resistance. The inner tube 1 can be formed of, for example, quartz glass or the like.

The light emitting unit 11 has a substantially ellipsoidal outer shape. The light emitting unit 11 is provided near the center of the inner tube 1 . The dimension (ball length) of the light emitting part 11 in the axial direction of the inner tube 1 can be set to about 8 mm, for example. The dimension of the light emitting part 11 in the direction perpendicular to the axial direction of the inner tube 1 can be, for example, about 6 mm.

A discharge space 111 is provided inside the light emitting unit 11 . The central portion of the discharge space 111 has a substantially cylindrical shape. Both ends of the discharge space 111 are substantially conical.

A discharge medium is sealed in the discharge space 111 . The discharge medium contains metal halides 2 and inert gases.

In addition, in the discharge lamp 100 of the present embodiment, the discharge medium does not substantially contain mercury from the viewpoint of environmental protection. In addition, in the present specification, "mercury is not substantially contained" not only does not contain mercury at all, but also allows mercury to be contained to an impurity level. For example, the discharge medium can contain mercury as long as it is less than 2 mg/cc in the discharge space 111 .

The metal halide 2 can include, for example, scandium (Sc) halides, indium (In) halides, sodium (Na) halides, and zinc (Zn) halides. For example, iodine (I) can be illustrated as a halogen. However, instead of iodine, bromine (Br), chlorine (Cl), or the like can also be used.

In addition, details related to the composition of the metal halide 2 will be described later.

The inert gas enclosed in the discharge space 111 can be, for example, xenon. In addition, other than xenon, neon, argon, krypton, etc., or a mixed gas obtained by combining these gases can be used.

However, the inert gas is more preferably xenon.

The sealing portion 12 has a plate shape, and is respectively bonded to both ends of the light emitting portion 11 . For example, the sealing portion 12 can be formed using a pinch seal method. Furthermore, the sealing portion 12 may be a cylindrical sealing portion formed by a shrink seal method. The cylindrical portion 14 is joined to one sealing portion 12 via the boundary portion 13 .

The boundary portion 13 and the cylindrical portion 14 are joined to the end portion of the sealing portion 12 on the side opposite to the light emitting portion 11 side.

The electrode mounting frame 3 is provided inside the sealing part 12 .

The electrode mounting frame 3 includes a metal foil 31 , an electrode 32 , a coil (coil) 33 and a lead wire 34 .

Metal foil 31 is provided inside sealing portion 12 . Metal foil 31 is bonded to the vicinity of the end of electrode 32 on the side opposite to discharge space 111 .

The metal foil 31 has a thin plate shape and can be formed of, for example, molybdenum, a molybdenum-rhenium alloy, tungsten, a tungsten-rhenium alloy, or the like.

The electrodes 32 have a linear shape. The cross-sectional shape of the electrode 32 can be circular, for example. The thickness of the electrode 32 (when the cross-sectional shape is circular, the thickness is a diameter) can be set to, for example, 0.2 mm or more and 0.4 mm or less.

In addition, the thickness of the electrode 32 may not be constant in the direction in which the electrode 32 extends. For example, the thickness of the electrode 32 may be thicker on the tip side than on the base side. In addition, the tip portion of the electrode 32 may have a spherical shape. In addition, like the direct current lighting type, the thickness of one electrode may be different from the thickness of the other electrode.

One end of the electrode 32 protrudes into the discharge space 111 . That is, one end of the electrode 32 is provided inside the discharge space 111 , and the other end is provided inside the sealing portion 12 . The pair of electrodes 32 are provided so as to face each other with a predetermined distance therebetween. The distance between the tips of the pair of electrodes 32 (inter-electrode distance) can be, for example, not less than 3.4 mm and not more than 4.4 mm. The other end of the electrode 32 is joined to the vicinity of the end of the metal foil 31 on the light emitting unit 11 side. For example, the electrode 32 and the metal foil 31 can be joined by laser welding.

The electrode 32 can be formed of, for example, pure tungsten, doped tungsten, tungsten-rhenium alloy, or the like. In addition, the electrode 32 may or may not contain thorium.

The coil 33 is provided to suppress cracks in the sealing portion 12 .

The coil 33 can be formed, for example, from a metal wire containing doped tungsten. The coil 33 is provided inside the sealing portion 12 . The coil 33 is wound outside the electrode 32 . For example, the wire diameter of the coil 33 can be set to about 30 μm to 100 μm, and the coil pitch (coil pitch) can be set to 600% or less.

The lead wire 34 has a linear shape. The cross-sectional shape of the lead wire 34 can be circular, for example. The lead wire 34 can be formed, for example, of molybdenum or the like. One end side of the lead wire 34 is bonded to the vicinity of the end portion of the metal foil 31 on the side opposite to the light emitting unit 11 side. The lead wire 34 and the metal foil 31 can be bonded by laser welding. The other end side of the lead wire 34 extends to the outside of the inner tube 1 .

The support wire 35 has an L-shape and is joined to the end of the lead wire 34 protruding from the front end side of the discharge lamp 100 . The support wire 35 and the lead wire 34 can be joined by laser welding. The support wire 35 can be formed of nickel, for example.

The sleeve 4 covers the part of the support wire 35 that extends parallel to the inner tube 1 . The sleeve 4 is, for example, cylindrical. The sleeve 4 can be formed, for example, from ceramics.

The metal band 71 is fixed to the vicinity of the rear end side end of the outer tube 5 .

The lamp holder 102 includes a main body 61 , an installation fitting 72 , a bottom terminal 81 and a side terminal 82 .

The main body portion 61 is formed of an insulating material such as resin. Inside the main body portion 61 are provided the rear end side of the lead wire 34 , the rear end side of the support wire 35 , and the rear end side of the sleeve 4 .

The mounting fitting 72 is disposed at an end of the main body portion 61 . The attachment fitting 72 is provided on the front end side of the main body portion 61 . The mounting fitting 72 protrudes from the main body portion 61 . The mounting fitting 72 holds the metal strap 71 . The metal band 71 is held by the mounting fitting 72 , thereby holding the burner 101 to the socket 102 .

The bottom terminal 81 is provided inside the main body portion 61 . The bottom terminal 81 is provided on the rear end side of the main body portion 61 . The bottom terminal 81 is formed of a conductive material. The bottom terminal 81 is electrically connected to the lead wire 34 .

The side terminal 82 is provided on the side wall of the main body 61 . The side terminal 82 is provided on the rear end side of the main body portion 61 . The side terminal 82 is formed of a conductive material. The side terminal 82 is electrically connected to the support wire 35 .

The bottom terminal 81 and the side terminal 82 are electrically connected to an unillustrated lighting circuit. In this case, the bottom terminal 81 is electrically connected to the high voltage side of the lighting circuit. The side terminal 82 is electrically connected to the low-voltage side of the lighting circuit.

When the discharge lamp 100 is used as an automobile headlamp, the discharge lamp 100 is mounted with its center axis (tube axis) substantially horizontal and the support wire 35 positioned substantially at its lower end side (below). It should be noted that lighting the discharge lamp 100 mounted in such a direction is called horizontal lighting.

Here, discharge lamps that can be lit with lower power are required in response to the demand for power saving in recent years. For example, there is a need for a discharge lamp that can be turned on with an electric power of 22 W (watt) or more and 28 W (watt) or less when it is turned on stably.

When the discharge lamp is turned on with low power as described above, the temperature of the light emitting unit 11 is lower than when the discharge lamp is turned on with a power of about 35W (Watt). If the temperature of the light emitting unit 11 is lowered, there is a problem that the luminance becomes dark due to the lowering of the luminous efficiency.

In this case, the luminous efficiency can be improved by increasing the ratio of the scandium halide contained in the metal halide 2 . However, if only the ratio of the scandium halide is increased, the tube voltage will increase and flicker will easily occur.

After research by the present inventors, it was found that as long as the ratio (Mn/Ms) of the weight Mn (μg) of the halide of sodium to the weight Ms (μg) of the halide of scandium is within a specified range, even the discharge lamp 100 is lit by low power, which can also improve luminous efficiency and suppress the rise of tube voltage.

Table 1 is a table illustrating the relationship between the ratio of the weight Mn of sodium halide to the weight Ms of scandium halide (Mn/Ms) and the luminous efficiency and tube voltage.

[Table 1]

Mn/Ms 0.7 0.8 0.9 1.1 1.3 1.5 Luminous efficiency ○ ○ ○ ○ ○ x Tube voltage x ○ ○ ○ ○ ○ Comprehensive judgment x ○ ○ ○ ○ x

In addition, in the evaluation of luminous efficiency, 80 lm/W (lumen/watt) or more was evaluated as "◯", and less than 80 lm/W (lumen/watt) was evaluated as "×".

In the evaluation of the tube voltage, the case where the tube voltage at startup was 48V or less was evaluated as "◯", and the case where it exceeded 48V was evaluated as "×".

The applied voltage for stable lighting is set to about 25W (watts), and the applied voltage for start-up is set to about 55W (watts).

In addition, as an example, the halide of scandium is scandium iodide (ScI ₃ ), and the halide of sodium is sodium iodide (NaI).

In this case, the metal halides 2 include scandium iodide, sodium iodide, indium iodide and zinc iodide.

In addition, the weight of the metal halide 2 was set to 400 μg.

The material of the light emitting unit 11 is quartz glass.

The volume of the discharge space 111 was set to 22 μL.

The inert gas sealed in the discharge space 111 was xenon, and the sealing pressure was 12 atm.

The diameter of the electrode 32 was set to 0.28 mm.

According to Table 1, as long as 0.8≦Mn/Ms≦1.3 is set, even if the discharge lamp 100 is lighted with a power of 22W (Watt) or more and 28W (Watt) or less when it is turned on stably, the luminous efficiency can be improved. And suppress the rise of the tube voltage.

Here, the valency of sodium iodide is 1, but the valence of scandium iodide is 3. Therefore, when the ratio of scandium iodide is increased, free iodine tends to increase. When free iodine increases, iodine tends to react with the material of the metal foil 31 , and cracks (foil cracks) accompanying corrosion of the metal foil 31 tend to occur. If foil cracks are likely to occur, the lifetime of the discharge lamp 100 may be shortened.

That is, if Mn/Ms becomes smaller, the lifetime of the discharge lamp 100 may be shortened.

As a result of research by the present inventors, it was found that the increase in free iodine can be suppressed by increasing the ratio of the indium halide contained in the metal halide 2 .

The findings can be explained in the following manner.

The valence of the halide of indium is 1 to 3 valences. Therefore, indium becomes a getter of free iodine, so increasing the ratio of the halide of indium can suppress the increase of free iodine.

That is, if the ratio of the indium halide is increased, the generation of foil cracks can be suppressed, and the lifetime of the discharge lamp 100 can be extended.

However, according to the findings obtained by the present inventors, it has become clear that the chromaticity x and the chromaticity y in the CIE1931xy chromaticity diagram decrease together when the ratio of the indium halide is increased. In this case, too, it has become clear that the chromaticity y is lowered more than the chromaticity x.

In particular, when the discharge lamp 100 is started, since the temperature of the light-emitting part 11 is low, indium with a low melting point evaporates first, and the light emitted by indium dominates. When the light emitted by indium is dominant, the chromaticity y is further reduced, and reddish light is emitted from the discharge lamp 100 .

That is, if the ratio of the indium halide is increased, the lifetime will be extended, but it may be difficult to irradiate light of a desired color.

Depending on the application of the discharge lamp 100, there is no problem even if reddish light is emitted from the discharge lamp 100 at the time of start-up. However, for example, when the discharge lamp 100 is an HID lamp used in an automobile headlight, it is preferable to emit white light from the discharge lamp 100 at the time of startup and stable lighting.

As a result of further studies, the present inventors have found that if the ratio of indium halides is within a predetermined range, the lifetime can be prolonged and light of a desired color (for example, white light) can be emitted.

Table 2 is a table illustrating the relationship between the weight ratio of the indium halide to the metal halide 2 and the lifetime and the color of light at startup.

[Table 2]

Indium halide weight ratio (wt%) 0.2 0.3 0.5 1.5 1.7 2 2.2 life x ○ ◎ ◎ ◎ ◎ ◎ The color of the light at startup ◎ ◎ ◎ ◎ ○ ○ x Comprehensive judgment x ○ ◎ ◎ ○ ○ x

In addition, in the life evaluation, the case where no foil cracks occurred for 3000 hours or more was evaluated as "◯", and the case where foil cracks were not generated for 3500 hours or more was evaluated as "⊚".

In addition, regarding the color of light at the time of activation, the case where the minimum value of y was 0.28 or more was evaluated as "◯", and the case where the minimum value of y was 0.29 or more was evaluated as "⊚". Here, the minimum value of y is the lowest value of y when the color of light changes with time during the period from startup to stabilization.

Furthermore, it has been confirmed that if the minimum value of y at startup is equal to or greater than 0.28, the color of light at the time of stable lighting is 0.355<x<0.400, and 0.640x+0.130≤y≤0.64x+0.150.

Furthermore, x is the chromaticity x in the CIE1931xy chromaticity diagram, and y is the chromaticity y.

In addition, as an example, the halide of indium is indium iodide (InI).

Other evaluation conditions are the same as those in Table 1.

From Table 2, it can be seen that white light can be irradiated even at the time of start-up if the weight ratio of the halide of indium is 0.3 wt% or more and 2.0 wt% or less.

In addition, if the weight ratio of the halide of indium is 0.5 wt % or more and 1.5 wt % or less, white light can be irradiated more easily even at the time of start-up.

As described above, as long as 0.8≦Mn/Ms≦1.3 and the weight ratio of the indium halide to the metal halide 2 is 0.3 wt% or more and 2.0 wt% or less, the discharge lamp 100 is lit by low power, and can also improve the luminous efficiency, suppress the rise of the tube voltage, prolong the life, and irradiate the light of desired color (for example, white light).

In addition, if the weight ratio of the indium halide to the metal halide 2 is 0.5 wt % or more and 1.5 wt % or less, desired color light (for example, white light) can be emitted more easily.

As mentioned above, some embodiments of the present invention have been illustrated, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in other various forms, and various omissions, substitutions, changes, etc. can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope or gist of the invention, and are included in the invention described in the claims and their equivalents. In addition, the above-described embodiments can be implemented in combination with each other.

Claims (4)

1. A discharge lamp, which can be lit by more than 22 watts and less than 28 watts of electricity when it is stably lit, the discharge lamp is characterized in that it comprises: a light-emitting part having a discharge space sealed therein with a discharge medium containing a metal halide and an inert gas and substantially not containing mercury; and a pair of electrodes protruding into the discharge space and arranged facing each other with a predetermined distance therebetween, The metal halides include scandium halides, sodium halides, indium halides and zinc halides, When the weight of the scandium halide is Ms and the weight of the sodium halide is Mn, 0.8≤Mn/Ms≤1.3, The weight ratio of the indium halide to the metal halide is 0.3 wt% or more and 2.0 wt% or less. 2. Discharge lamp according to claim 1, characterized in that: The weight ratio of the indium halide to the metal halide is 0.5 wt% or more and 1.5 wt% or less. 3. A discharge lamp as claimed in claim 1 or 2, characterized in that: When it is turned on stably, it can emit light with a chromaticity satisfying the following formula, 0.355<x<0.400, 0.640x+0.130≤y≤0.64x+0.150 Among them, x is the chromaticity x in the CIE1931xy chromaticity diagram, and y is the chromaticity y in the CIE1931xy chromaticity diagram. 4. Discharge lamp according to claim 1 or 2, characterized in that: When activated, it is possible to emit light with a chromaticity satisfying the following formula, y≥0.28 where y is the chromaticity y in the CIE1931xy chromaticity diagram.