JP2000215850A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp with highly accurate light distribution characteristics by suppressing the deformation of an arc tube and an outer tube generating when the outer can and the arc tube are welded. SOLUTION: An arc tube 1 has a pair of electrodes 5a, 5b on the inside, and also has a metal halide and a noble gas sealed on the inside. An outer tube 2 enveloping the arc tube 1 and welded to the arc tube 1 at the opposite ends is mainly made of silicon dioxide and contains boron. Temperature in welding of the arc tube and at least one end of the outer tube 2 is lowered, deformation of the arc tube 1 and the outer tube 2 is suppressed, and a discharge lamp having highly accurate light distribution characteristics can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp used for a headlight of an automobile or a backlight source of a liquid crystal projector.

[0002]

2. Description of the Related Art Conventionally, in order to prevent deterioration of a reflecting mirror, a front glass and the like of an appliance due to ultraviolet rays radiated from a discharge lamp, an additive for cutting ultraviolet rays is added to an arc tube of the discharge lamp. It is known that at least one end of a tube is fused.

[0003]

However, in such a conventional discharge lamp, since the softening temperature of the outer tube is high, when the arc tube is fused to at least one end of the outer tube to the arc tube having a pair of electrodes. The arc tube is softened, and the electrode is shifted from an appropriate position. Due to the positional displacement of the electrodes, the position of the arc generated between the electrodes is also displaced, and there is a problem that the light distribution cannot be performed with high accuracy.

The present invention has been made in order to solve such a problem, and suppresses deformation of the arc tube at the time of fusion of the arc tube and at least one end of the outer tube, and appropriately sets the positions of the electrodes. By doing so, a discharge lamp having a highly accurate light distribution characteristic is provided.

[0005]

DISCLOSURE OF THE INVENTION The discharge lamp of the present invention comprises:
An arc tube having electrodes at both ends, surrounding the arc tube,
And an outer tube having at least one end fused to the arc tube, wherein the outer tube has silicon dioxide as a main component and boron. The content of boron is preferably 0.12% by weight or more.

With this configuration, the softening temperature of the outer tube is lowered,
Since the processing temperature for fusing at least one end of the arc tube and the outer tube can be reduced, deformation of the arc tube can be prevented.

In the discharge lamp according to the present invention, when the distance between the innermost surface of the outer tube and the outer surface of the light emitting portion of the arc tube is D (mm), the distance D and the outer portion of boron are provided. The content in the tube (w _B weight%) is w _B / D ≦ 120
The following relational expression is satisfied.

With this configuration, it is possible to prevent the softening temperature of the outer tube from extremely lowering due to the excessive content of boron in the outer tube, and to prevent the outer tube from being deformed with the elapse of the lighting time of the discharge lamp. can do.

[0009] The discharge lamp of the present invention contains 0.12 boron.
% Or more, or has a relational expression of w _B / D ≦ 120, and the shortest distance from the tip of the electrode to the fusion portion between the arc tube and the outer tube is L (mm). The distance L and the content (w _B weight%) of boron in the outer tube satisfy a relational expression of w _B /L≦1.2.

[0010] With this configuration, it is possible to prevent the softening temperature of the outer tube from extremely dropping due to the excessive content of boron in the outer tube, and to reduce the fusion portion between the arc tube and the outer tube as the lighting time elapses. Deformation can be prevented.

In the discharge lamp of the present invention, the ratio of the input power W (W) of the discharge lamp to the distance D (mm) between the inner surface of the outer tube and the outer surface of the light emitting portion of the arc tube is closest. , W / D
≦ 2000.

With this configuration, it is possible to prevent the outer tube from being deformed as the temperature of the outer tube increases during the operation of the discharge lamp.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, in a metal halide lamp for a 35W automobile headlight according to an embodiment of the present invention, an arc tube 1 has a light emitting portion 1a and both ends thereof are sealed in a flat shape. Sealing portion 1b, 1c, and a cylindrical portion 1d connected to an end on the one sealing portion 1c side. The outer tube 2 surrounds the arc tube 1 and both ends are fused to both ends of the outer tube 2. Further, the arc tube 1
The end on the side of the cylindrical portion 1d is inserted into a groove at the center of the base 3 made of a resin such as polyetherimide, and is held by the base 3 by the holder 4 made of a conductor and the outer tube 2.
The light emitting portion 1a has a pair of electrodes 5a and 5b, and includes mercury and metal halides such as ScI ₃ and NaI.
And xenon as a starting gas. Metal foils 6b, 6a are embedded in the respective sealing portions 1b, 1c. One end of the electrode 5a is connected to one end of the metal foil 6a, and the tip of the other end of the electrode 5a is located in the light emitting section 1a. An external lead wire 7a is connected to the other end of the metal foil 6a.
Are connected at one end. Further, the external lead wire 7a
Is connected from the sealing portion 1c to the connecting portion 8a through the cylindrical portion 1d. Similarly, the electrode 5b, the metal foil 6b, and the external lead 7b are connected, and the other end of the external lead 7b is connected to one end of the power supply line 9, and the other end of the power supply line 9 is connected. It is connected to the unit 8b.

In the lamp shown in FIG. 1, an arc tube 1 having an inner volume of 0.025 cc and an arc length of 4.2 mm was used. Further, in the arc tube 1, a total of 20 mg of 80% by weight of NaI and 20% by weight of ScI ₃ and 50 mg of mercury were contained.
And 7 atm of xenon gas. Further, in the outer tube 2, the main component is silicon dioxide, and the composition of the additive of boron, aluminum and zirconium is variously changed.
As shown in Table 1, various outer tubes A to O were manufactured. Next, both ends of the outer tube A to the outer tube O were fused to separate arc tubes 1. When the presence or absence of deformation of the arc tube 1 after processing was examined, the results shown in Table 1 were obtained.

[0015]

[Table 1]

As shown in Table 1, outer tube A to outer tube L
Then, no deformation of the arc tube 1 after the fusion processing with the arc tube 1 occurred. From this, the total content of additives of boron, aluminum and zirconium in the outer tube 2 is set to 0.1.
It can be understood that a discharge lamp having a highly accurate light distribution characteristic can be obtained by defining 12 ≦ w _B + 2w _Al + 5w _Zr . On the other hand, the outer tube M, the outer tube N, and the outer tube in which the total content of the boron, aluminum, and zirconium additives is out of the range of 0.12 ≦ w _B + 2w _Al + 5w _Zr as in Comparative Examples 1 to 3. The arc tube 1 after each fusion processing of the tube O and the arc tube 1 was deformed.

The main components contained in the outer tube 2 are the outer tube I
Is shown below as an example.

Silicon dioxide: 90 wt% or more Boron: 0.94 wt% Aluminum: 0.26 wt% Zirconium: 0.07 wt% Cerium: 0.39 wt% Sodium: 0.0072 wt% Titanium: 0.0032 % By weight Calcium: 0.0016% by weight If the total content of the additives of boron, aluminum and zirconium is too large, the softening temperature of the outer tube 2 becomes too low, so that at least one end of the arc tube 1 and the outer tube 2 The outer tube 2 is deformed during the welding process. Therefore, the upper limit of the total content of the boron, aluminum and zirconium additives is defined by the results in Tables 2 and 3 as shown below.

In the lamp using the outer tube A or the outer tube O, the distance D (= 0.01, 0.02) between the inner surface of the outer tube 2 and the outer surface of the light emitting portion 1a of the arc tube 1 is closest. , 0.0
5, 0.1 mm) of outer tube A to outer tube O
When the presence or absence of deformation after lighting for 0 hours was examined, the results shown in Table 2 were obtained.

[0020]

[Table 2]

For example, when D = 0.01 mm, as shown in Table 2, the outer tube A, the outer tube C, the outer tube D, the outer tube F, the outer tube H,
Outer tube A, outer tube C, outer tube D, outer tube F, outer tube H, outer tube M, outer tube N after outer tube M, outer tube N, outer tube O and arc tube 1 after each fusion processing The outer tube O did not deform. From this, the total content of the boron, aluminum and zirconium additives in the outer tube 2 is expressed as (w _B + 2w _Al + 5w _Zr ) / D ≦ 12
It can be seen that by defining 0, deformation of the outer tube 2 due to lamp lighting can be prevented, and time degradation of the light distribution characteristics of the lamp can be suppressed. On the other hand, boron as before Comparative Example 10 Comparative Example 4 shown in Table 2, the total content of additives of aluminum and zirconium _{(w B + 2w A l +} 5w Zr) /
The softening temperature of the outer tube B, the outer tube E, the outer tube G, the outer tube I, the outer tube J, the outer tube K, and the outer tube L outside the range of 0.02 ≦ 120 is extremely lowered, and the lamp lighting time is reduced. Outer tube B over time,
Outer tube E, outer tube G, outer tube I, outer tube J, outer tube K, and outer tube L were deformed.

In the lamp using the outer tube A or the outer tube O, the arc tube 1 is connected from the tip of the electrode 5a or 5b.
The welded portion between the arc tube 1 and the outer tube A or the outer tube O with respect to the shortest distance L to the end face of the fused portion between the outer tube 2 and the light emitting portion 1a was examined for deformation after lighting for 1000 hours. However,
The results as shown in Table 3 were obtained.

The shortest distance L is the distance from the tip of the electrode 5a to the end face on the light emitting portion 1a side of the fusion portion between the arc tube 1 and the outer tube 2, and the distance from the tip of the electrode 5b to the light emitting tube 1 and the outer tube 2. And the distance from the fused portion to the end face on the light emitting portion 1a side, whichever is shorter. However, this case also includes a case where both are at the same distance.

[0024]

[Table 3]

For example, when L = 0.1 mm, as shown in Table 3, outer tube A, outer tube C, outer tube F, outer tube H, outer tube M, outer tube N, outer tube O and arc tube 1 Did not deform. From this, the total content of the boron, aluminum and zirconium additives in the outer tube 2 was calculated as (w _B + 2w
By defining _Al + 5w _Zr ) /L≦1.2, it is possible to prevent deformation of each fused portion between the arc tube 1 and the outer tube 2 due to lamp lighting, and to suppress time degradation of the light distribution characteristics of the lamp. Understand. On the other hand, Comparative Examples 11 to 18 shown in Table 3
Boron as before, the total content of additives of aluminum and zirconium _{(w B + 2w Al + 5w} Zr) / 0.
The softening temperature of the outer tube B, the outer tube D, the outer tube E, the outer tube G, the outer tube I, the outer tube J, the outer tube K, and the outer tube L outside the range of 1 ≦ 1.2 is extremely low, and Of the arc tube 1 and the outer tube B, the outer tube D, the outer tube E, the outer tube G, the outer tube I, the outer tube J, the outer tube K, and the outer tube L, as the lighting time elapses. Occurred.

Next, with reference barium, in addition to aluminum and zirconium, the more potassium (w _K weight percent) and barium additive of outer tube P to the outer tube V plus the (w _Ba wt%), Table 1 A lamp having the same structure as that of the lamp used in Example 1 was manufactured. Using this lamp, the presence or absence of devitrification of the outer tube P or the outer tube V after the lamp was lit for 1000 hours was examined. The results shown in Table 4 were obtained.

[0027]

[Table 4]

As shown in Table 4, no devitrification was observed in the outer tube P, the outer tube Q, the outer tube R, and the outer tube S. This is due to the high ionization tendency of these elements, and therefore alkali metals including potassium and barium,
The total addition amount of alkaline earth metals (lithium, sodium, rubidium, cesium, beryllium, magnesium, calcium, strontium and barium) is set to 0.
It can be seen that by setting the content to 1% by weight or less, it is possible to prevent the outer tube 2 from being devitrified and to suppress the time degradation of the light distribution characteristics of the lamp. On the other hand, the outer tubes T, U, and V in which the added amounts of potassium and barium exceeded 0.1% by weight as in Comparative Examples 19 to 21 were devitrified.

Barium, aluminum and zirconium
Cerium (w)_CeWt%), titanium
(W_TiWt%), iron (w_FeWt%), praseodymium
(W _PrWt%) and europium (w_EUWeight%)
Outer tube W to outer tube Z and outer tube a to outer
The same configuration as that of the lamp used in Table 1 is used by using the tube
Made a lamp. Use this lamp to release
Harmful UV radiation dose K_UVInitial value and ramp
Examination of the total luminous flux yielded the results shown in Table 5.
Was.

[0030]

[Table 5]

The harmful ultraviolet radiation amount K _UV is represented by the following equation (1).

[0032]

(Equation 1)

Cerium as in Comparative Example 22 shown in Table 5,
The outer tube g to which titanium, iron, praseodymium and europium are not added has a harmful ultraviolet radiation amount _KUV value of 2.
25 × 10 ⁻⁵ , whereas outer tubes W, X, containing at least one of cerium, titanium, iron, praseodymium and europium as in Examples 32 to 41. The outer tube Y, the outer tube Z, and the outer tube a to the outer tube f have the harmful ultraviolet ray amount _KUV value reduced by about 10% or more, and it can be seen that the deterioration of the reflecting mirror, the front glass, and the like can be suppressed. However, Comparative Example 23 and Comparative Example 2
The outer tube h, outer tube i, and outer tube j to which cerium, titanium, iron, praseodymium, and europium are added in excess of 1% by weight as in 5, also cut off visible light of 380 nm or more. Since the total luminous flux is attenuated, it is understood that the total amount of cerium, titanium, iron, praseodymium and europium added to the outer tube 2 should be regulated to 1% by weight or less.

The weight ratio of sodium halide NaX to scandium halide ScX ₃ in the metal halide sealed in the lamp of the above embodiment is set to 1 <NaX
It was confirmed that by controlling the ratio to / ScX ₃ <20, the average color rendering index Ra can be 70 or more, and the luminous flux maintenance factor after lighting for 1000 hours can be 80% or more. However, Br may be used as the halogen.

In the above embodiment, boron, aluminum, and zirconium are used as additives, but only boron may be used.

In the above embodiment, a discharge lamp having a structure in which both ends of the outer tube are fused to the arc tube has been described. However, the present invention has a structure in which one end of the outer tube is fused to the arc tube. It can also be implemented for discharge lamps.

[0037]

As described above, according to the present invention, the processing temperature at the time of fusing the arc tube and at least one end of the outer tube is reduced, the deformation of the arc tube and the outer tube is suppressed, and the arrangement with high precision is achieved. It is possible to provide a discharge lamp having optical characteristics.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a metal halide lamp for a 35W automobile headlight according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 1a Light emitting part 2 Outer tube 5a, 5b Electrode

Continuation of the front page (72) Inventor Takeshi Saito 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. F-term (reference) 5C039 HH03 5C043 AA04 AA20 BB04 BB09 CC01 CD02 CD05 DD02 EB15 EC06

Claims (10)

[Claims] 1. An arc tube having electrodes at both ends and an outer tube surrounding the arc tube and having at least one end fused to the arc tube, wherein the outer tube is mainly composed of silicon dioxide. A discharge lamp comprising boron. 2. The discharge lamp according to claim 1, wherein the discharge lamp contains 0.12% by weight or more of boron. 3. When the distance of the closest part between the inner surface of the outer tube and the outer surface of the light emitting portion of the arc tube is D (mm), the distance D and the content of boron (w _B weight%) satisfies the relational expression w _B / D ≦ 120. 4. When the shortest distance from the tip of the electrode to the fusion part between the arc tube and the outer tube is L (mm),
The shortest distance L and content of boron into the outer tube and (w _B wt%), but according to claim 2 or claim 3, characterized in that meet w _B /L≦1.2 relational expression Discharge lamp. 5. The outer tube further contains at least one of aluminum (w _Al wt%) and zirconium (w _Zr wt%) in addition to boron (w _B wt%).
2. The discharge lamp according to claim 1, wherein the content is such that 2 ≦ w _B + 2w _Al + 5w _Zr is satisfied. 3. 6. When the distance of the closest part between the inner surface of the outer tube and the outer surface of the light emitting portion of the arc tube is D (mm), the distance D and the distance of boron, aluminum and zirconium to the outer tube are determined. the total content of the _{((w B + 2w Al +} 5w Zr) by weight _{percent), (w B + 2w Al +} 5w Zr) / D ≦ 120 ( however, either the w _Al and w _Zr including 0) relational expression The discharge lamp according to claim 5, wherein the following condition is satisfied. 7. When a shortest distance from a tip of the electrode to a fusion portion between the arc tube and the outer tube is L (mm),
The shortest distance L and the total content of boron, aluminum and zirconium in the outer tube ((w _B + 2w _Al +5
(w _Zr )% by weight) is (w _B + 2w _Al + 5w _Zr ) / L ≦
7. The discharge lamp according to claim 5, wherein the relational expression 1.2 (where either one of w _Al and w _Zr includes 0) is satisfied. 8. The ratio between the input power W (W) of the discharge lamp and the distance D (mm) between the inner surface of the outer tube and the outer surface of the light emitting portion of the arc tube is W / D ≦ The discharge lamp according to any one of claims 1 to 7, wherein the discharge lamp satisfies 2000. 9. The outer tube contains 0.1% by weight or less of an element or a mixture of at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, and barium. 2. The method according to claim 1, wherein
A discharge lamp according to any one of claims 8 to 10. 10. The outer tube is made of cerium, titanium,
Iron, praseodymium and europium at least one element or mixture of at least one of the group consisting of 0.01
The discharge lamp according to any one of claims 1 to 9, wherein the content of the discharge lamp is from 1% by weight to 1% by weight.