JP2003282024A - High-pressure discharge lamp and sealing method of its bulb - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-pressure discharge lamp and a sealing technology of its bulb wherein a rupture and blackening of a quartz bulb can be prevented, and there is no occurrence of failure such as a crack in a quartz bulb sealing part and an electrode falling out or the like, even when it is actuated for a long time. <P>SOLUTION: In the high-pressure discharge lamp in which the quartz bulb and a pair of electrodes are provided, a pair of electrodes are opposedly arranged, and the quartz bulb is air-tightly sealed at a sealing part of the quartz bulb together with one part of the electrode, this is the high-pressure discharge lamp characterized that the maximum value of the surface roughness of the tip part of the electrode, is 5 μm or less, and the high-pressure discharge lamp and the sealing technology of this bulb wherein the length of a contact part between the electrode and the quartz bulb at the sealing part is within a prescribed range. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure discharge lamp and its bulb sealing technique, and more specifically, it has a low defect rate in manufacturing, and a quartz glass bulb cracks even when it is operated for a long time. The present invention relates to a high pressure discharge lamp capable of preventing a quartz glass bulb from exploding or blackening of a quartz glass bulb and a sealing technique for the bulb.

[0002]

2. Description of the Related Art High-pressure discharge lamps represented by xenon lamps, high-pressure mercury lamps, metal halide lamps, etc. are generally used as light sources for copying machines, projectors, etc. because of their high brightness and good color rendering properties. The high pressure discharge lamp
For example, a pair of electrodes are arranged to face each other in a tubular quartz glass bulb (hereinafter referred to as "quartz bulb") consisting of a light emitting space bulging portion and a sealing portion, and each electrode is welded to molybdenum foil or the like. The structure is joined by the means. In addition, in the sealing portion of the quartz bulb, a part of the electrode and the molybdenum foil are hermetically sealed. The light emitting space bulging portion of the hermetically sealed quartz bulb is filled with, for example, mercury and an inert gas.

As a method of hermetically sealing the quartz valve, there are a pinch seal and a shrink seal. The pinch seal is a method of crushing and sealing the outer peripheral portion of the quartz valve by pressing with a pressing die such as a die. However, this pinch seal is liable to cause residual strain after being pressed, and in addition, since the contact shape between the quartz valve and the sealing metal after pressing is not uniform, stress concentration is likely to occur and the above-mentioned high pressure release is caused. If applied to the sealing of electric lamps, the quartz bulb may burst.

The shrink seal is a method of heating the outer circumferences of both ends of the quartz valve in a state where a pressure difference is generated between the inside and the outside of the quartz valve, and then naturally contracting the quartz valve to perform hermetic sealing. . According to this method, the quartz valve is naturally contracted at the time of sealing, so that unlike the pinch seal, an unreasonable pressure is not applied to the valve and residual strain is unlikely to occur. Further, since the contact shape between the quartz bulb and the sealing metal foil is almost uniform, stress concentration does not occur. For this reason, this shrink seal is often used to seal the above-mentioned high pressure discharge lamp.

In the above high pressure discharge lamp, external lead wires are joined to the molybdenum foils sealed at both ends of the quartz bulb, and a predetermined trigger voltage is applied to these external lead wires. When the trigger voltage is applied, glow discharge is induced between both electrodes in the atmosphere of the inert gas in the quartz bulb, and the enclosed mercury is vaporized, and plasma discharge is generated in the high-pressure mercury gas. The light emitted by the plasma discharge has high brightness and good color rendering.

[0006]

SUMMARY OF THE INVENTION Such a high pressure discharge lamp is
There is a problem that sputtering during operation is intense and blackening of the quartz bulb occurs in a short time. Further, in order to prevent blackening due to such electrode sputtering, when an attempt is made to increase the halogen content by increasing the halogen content in the high pressure discharge lamp, the electrode sealing portion is eroded by the halogen gas and cracks occur, There is a problem that the quartz bulb bursts.

Further, conventionally, when a bulb of a high pressure discharge lamp is sealed by a shrink seal, no consideration is given to the difference in thermal expansion coefficient between the quartz bulb and the electrode. Furthermore,
Conventionally, heating quartz glass during hermetic sealing is performed manually by a craftsman, and it is difficult to accurately form the contact portion between the electrode and the quartz bulb in the sealing portion to a specific length. Met. Therefore, when the contact portion between the electrode and the quartz bulb in the sealed portion is long, cracks as shown in FIG. 8 occur in the sealed portion due to the difference in thermal expansion coefficient between the electrode and the quartz bulb during the hermetic sealing. Was there. Such cracks become cracks when the high pressure discharge lamp is operated to increase the internal pressure of the quartz bulb, and cause the quartz bulb to burst. Although the generation of cracks can be suppressed by shortening the length of the contact portion between the electrode and the quartz bulb in the sealing portion, in that case, defects such as electrode omission may occur.

Therefore, according to the present invention, it is possible to prevent the quartz bulb from bursting or the quartz bulb to be blackened even when it is operated for a long time, and to suppress the occurrence of cracks during sealing. An object of the present invention is to provide a high-pressure discharge lamp and a method for sealing the bulb of the high-pressure discharge lamp, in which defects such as electrode omission do not occur.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, have found that the surface roughness of the tip portion of the electrode and the electrode portion in the bulging portion of the emission space of the quartz bulb other than the tip portion. Attention was paid to the surface roughness of the portion, the length of the portion of the sealing portion where the electrode and the quartz valve contact each other, and the surface roughness of the contact surface of the sealing portion with the quartz valve. The surface roughness of the tip portion (hereinafter referred to as “R ₁ ”)
If the maximum value (hereinafter referred to as “R ₁ max”) is set to a specific value or less, the sputtering of the electrode can be significantly reduced, and as a result, the blackening of the quartz bulb can be prevented. If the maximum value of the surface roughness (hereinafter referred to as “R ₂ ”) of the portion other than the tip portion of the electrode (hereinafter referred to as “R ₂ max”) is set within a specific range, it is possible to prevent the quartz valve from rupturing. In addition, defects such as crack generation and electrode omission due to the difference in thermal expansion coefficient between the quartz valve and the electrode in the sealing part are
The present invention has been completed by finding from the results of the experiments so far that it can be suppressed by defining the length of the contact portion between the electrode and the quartz bulb in the sealing portion within a certain range.

That is, the gist of the first invention of the present invention is that a pair of electrodes are arranged to face each other in a tubular quartz glass bulb, and the quartz glass bulb is provided with the pair of electrodes at the sealing portions at both ends of the quartz bulb. In a high-pressure discharge lamp that is sealed together with a part of the electrodes, the diameter of the pair of electrodes is D, and the power supplied to the electrodes is P, and the electrodes in the sealing portion and the quartz glass bulb are in contact with each other. The maximum length of the length L of the part is given by Lmax ≦ 200 ÷ (P × D), and the shortest length Lmin is given by: Lmin ≧ 0.8 ÷ (D ² × π) and Lmin ≧ 0.7 The present invention provides a high pressure discharge lamp characterized by being provided in a longer direction.

Further, the gist of the second invention of the present invention is to axially connect the first electrode to one of the insertion openings of a quartz glass bulb having a pair of insertion openings for inserting the electrodes formed at opposed positions. Set the position so that it is at the specified position, and with a predetermined pressure difference between the inside and outside of the quartz glass bulb, heat a prescribed portion of one insertion port of the quartz glass bulb, and Contracting to seal the quartz glass bulb together with part of the first electrode, and placing the second electrode in the other insertion opening of the quartz glass bulb so that the axial position is at a prescribed position. After setting, a predetermined pressure difference is generated between the inside and outside of the quartz glass bulb, and a predetermined portion of the other insertion opening of the quartz glass bulb is heated and naturally contracted so that the second electrode With some And a step of sealing the quartz glass-made bulb, a diameter of the first and second electrodes D,
The electric power supplied to each electrode is P, and the maximum length Lmax of the length L of the portion where the electrode and the quartz glass bulb are in contact with each other at the sealed portion of each insertion opening of the quartz bulb is Lmax ≦ 200. Given by ÷ (P × D), and the shortest length Lmin is given by the longer one of Lmin ≧ 0.8 ÷ (D ² × π) and Lmin ≧ 0.7. The present invention provides a method for sealing a valve.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional explanatory view showing an embodiment of a high pressure discharge lamp of the present invention, which is an example of a high pressure discharge lamp using a DC power supply. The shape of the light emission space bulging portion 11 of the integrally molded synthetic quartz glass bulb 1 may be spherical, elliptical, or the like. The shapes of the anode 2 and the cathode 3 are
It may be the same or different. There is no particular limitation on the distance between both electrodes. The anode 2 and the cathode 3 are molybdenum foils 4 and 4 '.
Are joined by means such as welding. The quartz bulb 1 is hermetically sealed with the molybdenum foils 4 and 4 ′ at the sealing portion 12. Mercury, an inert gas and the like are enclosed in the light emitting space bulging portion 11.

In the present invention, mercury is enclosed in the light emitting space bulging portion 11, and the enclosed amount is 0.12 to 0.12.
It is preferably 0.3 mg / mm ³ , and 0.18 to
It is particularly preferably 0.24 mg / mm ³ . Since the enclosed amount is 0.12-0.3 mg / mm ³ ,
It is possible to increase the luminous efficiency and prevent blackening and bursting during the operation of the high pressure discharge lamp.

In the present invention, a halo is provided inside the high pressure discharge lamp.
Gengas is enclosed, and the enclosed amount is 10^-8-10^-2
μmol / mm³And preferably 10^-6-10
^-Fourμmol / mm³Is particularly preferable. 10^-8
-10^-2μmol / mm³If so, increase the luminous efficiency
It is possible to prevent blackening and damage during high pressure discharge lamp operation.
It is possible to prevent cracks and the like. Where halogen gas and
Examples include chlorine gas, bromine gas, iodine gas, etc.
It is possible to encapsulate one or more of these. 2
When enclosing more than one kind of halogen gas, the total encapsulation
Quantity is 10^-8-10 ^-2μmol / mm³To be
Good

In the present invention, an inert gas is filled in the light emitting space bulging portion 11, and the filling pressure is 6 kP.
It is preferably a or more, and particularly preferably 20 to 50 kPa. If it is 20 kPa or more, it is possible to increase the luminous efficiency and prevent blackening and bursting during the operation of the high pressure discharge lamp. Here, examples of the inert gas include helium gas, neon gas, argon gas, krypton gas, xenon gas, and the like, and one or more of these can be enclosed. When two or more inert gases are filled, the total filling pressure is 50
It is preferably kPa or less.

In the present invention, the materials for the anode and cathode of the high pressure discharge lamp are preferably tungsten, molybdenum and tantalum, more preferably tungsten, and particularly preferably tungsten containing potassium oxide. The content of potassium oxide in tungsten is preferably 30 ppm or less. With tungsten containing potassium oxide, it is possible to increase the luminous efficiency and prevent leakage and bursting during operation of the high pressure discharge lamp.

First, regarding the first invention of the present invention,
explain. From the findings based on the results of experiments relating to the relationship between the length of the contact portion between the electrode and the quartz bulb in the sealed portion, such as the occurrence of cracks due to the difference in the coefficient of thermal expansion and the electrode omission, and the high pressure discharge lamp of the present invention, In the sealing method, the maximum length of the contact part between the electrode and the quartz bulb in the sealed part is specified as the length that does not cause cracks due to the difference in thermal expansion coefficient, and the shortest length is the length that does not cause electrode omission. Stipulated. Therefore, the conventional rupture due to the generation of cracks and the defect due to electrode omission do not occur.

FIG. 2 is a partial sectional structural view of a high pressure discharge lamp which is an embodiment of the present invention. In this high-pressure discharge lamp, the length L of the contact portion between the electrode 2a and the quartz bulb 1 in the sealing portion 12 is such that cracking due to the difference in thermal expansion coefficient between the quartz bulb and the electrode is suppressed, and The length is specified so that the electrodes do not come off.

In the high pressure discharge lamp of this embodiment, the electrodes 2a,
2b is bonded to molybdenum foils 4 and 4 ', respectively, and a part of the electrodes 2a and 2b and molybdenum foils 4 and 4'.
Are sealed at both ends of the quartz bulb 1. The quartz valve 1 is sealed by a shrink seal.

The electrode 2a and the quartz bulb 1 in the sealed portion
The length L of the contact portion with the diameter of the electrode 2a is D (m
m), when the supply power of the high pressure discharge lamp is P (W),
It is defined as follows. (Maximum length) Lmax (mm) ≦ 200 ÷ (P × D) (Shortest length) Lmin (mm) ≧ 0.8 ÷ (D ² × π) and Lmin (mm) ≧ 0.7 The length of the contact portion between the longer electrode 2b and the quartz bulb 1 is also defined so as to satisfy the above condition.

In a high pressure discharge lamp in which the length L of the contact portion between each electrode 2a, 2b and the quartz bulb 1 is defined under the above conditions, the contact portion between the quartz bulb 1 and the electrodes 2a, 2b is weak in strength. Does not occur and the occurrence of cracks at the contact portion is suppressed.
Even if operated as described above, the quartz bulb 1 will not burst.

Next, a method of deriving the above conditions will be specifically described. In the following description, in the quartz bulb 1,
0.12 to 0.30 mg / mm ³ of mercury and 10 ⁻⁸ to 10
^The conditions are derived using a sample containing ^-2 μmol / mm ³ of an inert gas.

FIG. 3 shows that the power supplied to the high pressure discharge lamp is 200 W.
As fixed, the electrode diameter φ is 0.4, 0.6, 0.8 (m
It is a figure which shows the relationship between the length L of the contact part of an electrode and a quartz valve, and a defective rate when it changes with m). FIG. 4 shows the length L of the contact portion between the electrode and the quartz bulb and the defect when the power supply of the high pressure discharge lamp is changed to 200 W, 150 W, and 120 W with the electrode diameter φ fixed at 0.6 (mm). It is a figure which shows the relationship of a rate. Here, the defect rate includes all defects such as a rupture of a quartz bulb, a defect such as electrode omission, which occurs during an operation up to the initial stage and the end of the life (here, 2000 hours), and a manufacturing defect.

Since a high-pressure discharge lamp is generally required to have a defect rate of 1% at the end of its life, here, the defect rate is 1 based on the data in FIGS. 3 and 4.
% Or less, length L of the contact portion between the electrode and the quartz bulb
The maximum length Lmax and the shortest length Lmin are calculated.

When the length L of the contact portion between the electrodes 2a and 2b and the quartz bulb 1 is long, cracks are generated due to the difference in thermal expansion coefficient between the electrodes and the quartz bulb during the hermetic sealing of the quartz bulb. Therefore, in order to suppress defects caused by the generation of cracks, it is necessary to define the maximum length L of the contact portion between the electrode and the quartz bulb. 3 and 4
According to the data, the defect rate increases in proportion to the diameter of the electrode and the amount of power supplied to the high pressure discharge lamp, but the length L of the contact portion between the electrode and the quartz bulb depends on the diameter of the electrode and the high pressure. The smaller the power supplied to the discharge lamp, the larger the value can be. That is, the maximum length L of the contact portion between the electrode and the quartz bulb is inversely proportional to the diameter D of the electrode and the magnitude P of the power supplied to the high pressure discharge lamp, and the coefficient is 200 from the data of FIGS. 3 and 4. Is asked. Therefore, the maximum length Lmax of the length L of the contact portion between the electrode and the quartz bulb is
Can be defined as: Lmax (mm) ≦ 200 ÷ (P × D)

On the other hand, if the length of the contact portion between the electrode and the quartz bulb is short, the portion supporting the electrode is weak in strength, and defects such as electrode omission occur. In order to prevent defects due to this electrode omission and the like, it is necessary to define the minimum length L of the contact portion between the electrode and the quartz bulb. The shortest length L of the contact portion between the electrode and the quartz bulb, which can obtain strength without causing defects such as electrode omission, depends on the diameter of the electrode and is inversely proportional to the cross-sectional area of the electrode. From the data of FIGS. 3 and 4, 0.8 is obtained. Therefore, the minimum length Lmin of the length L of the contact portion between the electrode and the quartz bulb can be defined as follows. Lmin (mm) ≧ 0.8 ÷ (D ² × π)

In the manufacture of the quartz bulb, the contact area between the electrode and the quartz bulb requires a welding margin of at least 0.7 mm, and if the length of the contact area is less than this value, the defective rate will increase dramatically. become. Therefore, the shortest length Lmin of the length L of the contact portion between the electrode and the quartz bulb needs to satisfy the above conditions and the following conditions. Lmin. (Mm) ≧ 0.7

FIG. 5 shows the shortest length Lmin in the electrode diameter D range of 0.4 to 0.8 mm and the maximum length Lmax when the power supplied to the high pressure discharge lamp is 200 W, 150 W and 120 W, respectively. By defining the length L of the contact portion between the electrode and the quartz bulb within the range shown in FIG. 5, the contact portion between the electrode and the quartz bulb is not weakened in strength, and It is possible to suppress the occurrence of cracks in the portion. Experimentally, it has been obtained that even if the internal pressure of the bulb is 8 MPa or more, the quartz bulb 1 is not ruptured at all.

FIG. 6 is a diagram showing a schematic configuration of a power supply system for a high pressure discharge lamp. External lead wires 5 and 5 ′ electrically connected to the molybdenum foils 4 and 4 ′ are provided at both ends of the high pressure discharge lamp, and a power source ( Predetermined electric power is supplied from the AC 6 (this example is an example of an AC power supply, but a DC power supply may be used). When the high pressure discharge lamp is turned on, first, a trigger voltage is applied to the external lead wires 5 and 5'to induce glow discharge between the electrodes 2a and 2b (or 2, 3). As a result, the mercury enclosed in the quartz bulb 1 is vaporized and plasma discharge is generated in the high-pressure mercury gas, so that light with high brightness and good color rendering is emitted. When the high pressure discharge lamp stably emits light, the control unit (not shown) controls the power supplied to the high pressure discharge lamp to be constant. Normally, in a stable state, a voltage of about 50 to 100 V in DC or AC is applied to the external lead wires 5 and 5 ', and 120 to 200 W of power is supplied to the high pressure discharge lamp.

The contact between the electrode and the quartz bulb by the sealing process is physical, and at the time of sealing, the fused quartz glass comes into contact with the surface of the electrode along the uneven shape (surface roughness). Solidify. When the contact area returns to room temperature after sealing, the shape of the contact surface of the solidified quartz glass and the surface shape of the electrode are slightly different due to the difference in the coefficient of thermal expansion between the electrode and quartz glass. Stress was generated in the part. The generation of such stress was also one of the causes of the generation of cracks.

FIG. 7 shows the relationship between the surface roughness R ₃ at the contact surface of the electrode with the quartz bulb and the defect rate. In the example of FIG. 7, a quartz valve having a power supply of 200 W, an electrode diameter φ of 0.6 mm, and a contact portion length of the electrode and the quartz valve of 1.2 mm is a surface of a contact surface of the electrode with the quartz valve. This is the percent defective with respect to the maximum value R ₃ max of roughness. A contact-type surface roughness meter is used to measure the surface roughness, and the maximum value R ₃ max of the surface roughness of the electrode is the distance from the axial center of the electrode at the contact portion with the quartz bulb to the surface. It is the maximum absolute value of the difference from the average value of the distance.

From the results shown in FIG. 7, it is understood that the smaller the surface roughness of the contact surface of the electrode, the lower the defective rate. As described above, the high-pressure discharge lamp is required to have a defect rate of 1% or less at the end of its life. Therefore, the maximum value R ₃ max of the surface roughness of the contact surface of the electrode is 5 μm or less. It is desirable that the thickness is 2 to 3 μm. By forming the surface of the electrode with such a surface roughness, it is possible to suppress the occurrence of cracks caused by the surface roughness of the electrode described above.

The following is an example of the characteristics of the high pressure discharge lamp of the present invention. Discharge lamp power: 120 to 200 W Discharge lamp voltage: 50 to 100 V Distance between electrodes: 1.0 to 2.0 mm Luminous efficiency: 40 to 70 lm / W Tube wall load: 0.8 to 1.5 W / mm ² Radiation wavelength: 360-700 nm

Next, the valve sealing procedure will be specifically described. The high-pressure discharge lamp shown in the present invention uses a quartz bulb in which a pair of insertion openings for inserting electrodes are formed at opposing positions, and airtight sealing is performed for each electrode in the first step and the second step. Do in two stages.

In the first step, one electrode is set in one insertion port so that the axial position is at a specified position, and the oxygen (O) partial pressure is evacuated to 2.5 × 10 ⁻³ Pa or less. . At this time, the filling pressure is 6 kPa to 6 in the quartz bulb.
An inert gas of 0 kPa may be introduced in some cases. After the exhaust
The quartz valve is filled with oxygen (O) partial pressure of 2.5 × 10 ⁻³ Pa or less in a vacuum state, or an inert gas with a filling pressure of 6 kPa to 60 kPa is filled, and the pressure inside and outside the quartz valve is atmospheric pressure. As a difference, a pressure difference of 101 kPa occurs in the vacuum state and 41 kPa to 95 kPa in the inert gas filled state. In such a pressure difference, by heating the outer periphery of the quartz bulb in the portion where the molybdenum foil is inserted, the quartz bulb is naturally contracted and the molybdenum foil and the quartz bulb are hermetically sealed.

In the second step, the mercury and the other electrode are set in the quartz bulb from the other opened insertion port so that the axial position is at the specified position, and the oxygen (O) partial pressure is 2. Exhaust to 5 × 10 −3 Pa or less. Then, a halogen gas and an inert gas are introduced into the quartz bulb. After evacuation, the filling pressure in the quartz bulb is 6 kPa.
A halogen gas and an inert gas of up to 60 kPa are enclosed, and a pressure difference of 41 kPa to 95 kPa is generated inside and outside the quartz bulb as a pressure difference from the atmospheric pressure. In such a pressure difference, the quartz bulb is naturally contracted by heating the outer periphery of the quartz bulb in the portion where the molybdenum foil is inserted, as in the first step, and the molybdenum foil and the quartz bulb are hermetically sealed.

[0037]

As described above, since cracks and electrode omissions at the time of sealing can be suppressed, the defect rate can be suppressed to a low level, and as a result, cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing an embodiment of a high pressure discharge lamp of the present invention.

FIG. 2 is a partial cross-sectional structural view of a high pressure discharge lamp that is an embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the length of the contact portion between the electrode and the quartz bulb and the defect rate when the electrode diameter is changed while the power supplied to the high pressure discharge lamp is fixed.

FIG. 4 is a diagram showing the relationship between the length of the contact portion between the electrode and the quartz bulb and the defect rate when the electric power supplied to the high-pressure discharge lamp is changed while the electrode diameter is fixed.

FIG. 5 is a diagram showing the shortest length in the electrode diameter range of 0.4 to 0.8 mm and the respective maximum lengths when the supply power is 200 W, 150 W, and 120 W.

FIG. 6 is a diagram showing a schematic configuration of a power supply system for a high pressure discharge lamp.

FIG. 7 is a diagram showing the relationship between the electrode surface roughness and the defect rate.

FIG. 8 is a schematic view of a crack generated in a sealed portion.

[Explanation of symbols]

1: Quartz valve 11: Light emitting space bulge 12: Sealing part 2: Electrode (anode) 21: Tip of electrode 3: Electrode (cathode) 31: Tip of electrode 2a, 2b: Electrode (AC) 4, 4 ': Molybdenum foil 5, 5 ': External lead wire 6: Power supply

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Claims (4)

[Claims] 1. A pair of electrodes are arranged to face each other in a tubular quartz glass bulb, and the quartz glass bulb is sealed together with a part of the pair of electrodes at sealing portions at both ends of the quartz glass bulb. In the high-pressure discharge lamp, the diameter of the electrode is D, the power supplied to the high-pressure discharge lamp is P, and the maximum length Lmax of the length L of the portion where the electrode and the quartz glass bulb are in contact with each other in the sealing portion is Lmin ≦ 200 ÷ (P × D), and the shortest length Lmin is given by the longer one of Lmin ≧ 0.8 ÷ (D ² × π) and Lmin ≧ 0.7. High pressure discharge lamp. 2. The maximum value of the surface roughness on the contact surface of the electrode with the quartz glass bulb, which is represented by the absolute value of the difference between the distance from the axial center of the electrode to the surface and the average value of the distance. Is 5 μm or less, the high pressure discharge lamp according to claim 1. 3. The high pressure discharge lamp according to claim 2, wherein the maximum value of the surface roughness of the electrode on the contact surface with the glass quartz bulb is 2 to 3 μm. 4. A first electrode is set in one of the insertion openings of a quartz glass bulb in which a pair of insertion openings for inserting electrodes are formed at opposed positions so that the axial position is at a specified position. A part of the first electrode by heating a predetermined portion of one insertion port of the quartz glass bulb while allowing a predetermined pressure difference between the inside and the outside of the quartz glass bulb to naturally contract. Together with the step of sealing the quartz glass bulb, and setting the second electrode in the other insertion port of the quartz glass bulb so that the axial position is at a specified position,
With a predetermined pressure difference generated between the inside and outside of the quartz glass bulb, a predetermined portion of the other insertion opening of the quartz glass bulb is heated and naturally contracted to form a part of the second electrode. Sealing the quartz glass bulb, wherein the diameter of the first and second electrodes is D, and the electric power supplied to the electrodes is P, and the sealed portion of each insertion opening of the quartz bulb. The maximum length Lmax of the length L of the part where the electrode and the quartz glass bulb are in contact with each other is given by Lmax ≦ 200 ÷ (P × D), and the shortest length Lmin is Lmin ≧ 0.8 ÷ (D ² × π) and Lmin ≧ 0.7, whichever is longer is given.