JP2011082062A - Short arc type discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a short arc type discharge lamp which can restrain deterioration of light output and has long lifetime. <P>SOLUTION: In the short arc type discharge lamp, wherein sealing tubes 21, 22 following to a light-emitting tube 1 and an anode lead rod 51 and a cathode lead rod 52 respectively supporting an anode 3 and a cathode 4 arranged in the light-emitting tube 1 are sealed with step-jointed glasses 61, 62 in the sealing tubes 21, 22, the anode lead rod 51 is retained by inserting into a cylinder 71 for retention, the cylinder 71 for retention is supported at a narrowing section 2a of the sealing tube 21, the cathode lead rod 52 is only supported with the step-jointed glass 62, and an internal space S1 of the light-emitting tube 1 and an internal space S2 of the sealing tube 22 where the cathode lead rod 52 is located are communicated with each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a short arc type discharge lamp used for a light source of a projection apparatus.

Conventionally, a short arc type discharge lamp as shown in FIG. 4 is known as a light source of a projection apparatus such as a projector.
In this short arc type discharge lamp, quartz glass sealing tubes 21 and 22 are formed at both ends of a quartz glass arc tube 1, and a pair of anode 3 and cathode 4 are arranged in the arc tube 1. The anode 3 is supported by an anode lead bar 51, and the cathode 4 is supported by a cathode lead bar 52.

  The anode lead bar 51 is sealed with a step glass 61 in the anode side sealing tube 21, and the cathode lead bar 52 is sealed with a step glass 62 in the cathode side sealing tube 22. Yes.

The anode lead bar 51 is inserted and held in a holding cylinder 71, and the holding cylinder 71 is supported by a narrowing portion 2 a that burns and narrows the sealing tube 21.
The cathode lead bar 52 is inserted into and held by a holding cylinder 72, and the holding cylinder 72 is supported by a narrowing portion 2b that burns and narrows the sealing tube 22.

Such a short arc type discharge lamp has a very high internal pressure of the arc tube 1 during lighting in order to increase the luminance, and therefore it is necessary to design the sealing tubes 21 and 22 so as not to be damaged even at a high internal pressure. Therefore, since a large current flows through the lamp, the anode lead bar 51 and the cathode lead bar 52 that support the anode 3 and the cathode 4 need to protrude directly from the sealing tubes 21 and 22 to the outside. For sealing the stop tubes 21, 22, the anode lead bar 51, and the cathode lead bar 52, a sealing structure using stepped glass 61, 62 is employed.
Such a short arc type discharge lamp is described in JP-A-2004-224552.

  However, recently, there has been a demand for a high-intensity lamp with an increased light output from a short arc type discharge lamp, and the lamp current tends to increase.

As the lamp current increases, the temperature of the electrode, particularly the anode into which electrons flow, rises. As a result, tungsten constituting the anode further evaporates.
The evaporated tungsten scatters in the arc tube, and eventually adheres to the inner wall of the arc tube as a blackened product.

As described above, when the blackened material adheres to the inner wall of the arc tube, the light from the arc is blocked by the blackened material, and there is a problem that the light output decreases early after the lamp is turned on.
JP 2004-22452 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a short-arc discharge lamp having a long life while suppressing a decrease in light output.

  The short arc type discharge lamp according to claim 1 is characterized in that a sealing tube following the arc tube, an anode lead rod disposed in the arc tube, and an anode lead bar and a cathode lead rod supporting the cathode are connected in stages in the seal tube. In the short arc type discharge lamp sealed with glass, the anode lead bar is inserted and held in a holding cylinder, and the holding cylinder is supported at a narrowing portion of the sealing tube, and the cathode The lead bar is supported only by the step glass, and the inner space of the arc tube and the inner space of the sealing tube where the cathode lead bar is located communicate with each other.

The short arc type discharge lamp according to claim 2 is the short arc type discharge lamp according to claim 1, and in particular, the joint glass sealed on the cathode lead rod is sealed on the cathode lead rod. A sealed portion, a rising portion that rises away from the cathode lead rod following the sealing portion, a virtual line that passes through the rising portion, and a longitudinal axis that passes through the center of the cathode lead rod; Is the distance from the intersection P to the cathode tip, L (mm), and the total weight W (gf) of the cathode lead and cathode on the cathode tip side from the intersection P, L × W is 230 ×× It is less than 10 ³ (mm · gf).

According to the short arc type discharge lamp of the present invention, the anode arranged in the arc tube, the anode lead rod for supporting the cathode and the cathode lead rod are sealed with the joint glass in the sealed tube, and the cathode lead The rod is supported only by the connecting glass, and the inner space of the arc tube and the inner space of the sealing tube where the cathode lead rod is located communicate with each other, so that the tungsten, particularly the tungsten constituting the anode, evaporates. However, since the temperature of the sealed tube is lower than that of the arc tube, the evaporated material can be adhered to the inner wall of the sealed tube by utilizing the property that the evaporated material adheres to the lower temperature portion.
In other words, the evaporation of tungsten, which constitutes the electrode, especially the anode, can be positively attached to the inner wall of the sealing tube from the inner wall of the arc tube, and the inner wall of the sealing tube becomes black, but the light emission Since the blackening of the inner wall of the tube is suppressed, the light from the arc is not blocked by the blackened material, and even if the lamp is turned on for a long time, the decrease in light output can be suppressed, and a long-life short arc discharge It becomes a lamp.

Furthermore, the cathode lead bar has a structure supported only by the step glass, and an intersection between a virtual line passing through the rising portion and a longitudinal axis passing through the center of the cathode lead bar is P, and the tip of the cathode from the intersection P Is L (mm), and the total weight W (gf) of the cathode lead and the cathode on the cathode tip side from the intersection P, L × W is set to a range less than 230 × 10 ³ (mm · gf). As a result, breakage of the step glass can be prevented.

It is a section explanatory view of the short arc type discharge lamp of the present invention. It is explanatory drawing for demonstrating the load concerning the step side glass on the cathode side. It is the experimental result which investigated the damage condition to the load concerning a step glass, and a rising part. It is sectional explanatory drawing of the conventional short arc type discharge lamp.

  FIG. 1 is a cross-sectional explanatory view of a short arc type discharge lamp of the present invention.

  As shown in FIG. 1, the short arc type discharge lamp of the present invention has quartz glass sealing tubes 21 and 22 formed at both ends of a quartz glass arc tube 1, and a pair of arc tube 1 is formed in the arc tube 1. A tungsten anode 3 and a cathode 4 are arranged. The anode 3 is supported by an anode lead bar 51, and the cathode 4 is supported by a cathode lead bar 52.

  The anode lead bar 51 is sealed with a step glass 61 in the anode side sealing tube 21, and the cathode lead bar 52 is sealed with a step glass 62 in the cathode side sealing tube 22. Yes.

  As shown in FIG. 2, the connecting glass 62 has a sealing part 621 sealed to the cathode lead bar 52 and a rising part 622 rising so as to be separated from the cathode lead bar 52 following the sealing part 621. It is.

The anode lead bar 51 is inserted and held in a holding cylinder 71, and the holding cylinder 71 is supported by a narrowing portion 2 a that burns and narrows the sealing tube 21.
The cathode lead rod 52 is supported only by the step glass 62 and has a structure in which the internal space S1 of the arc tube 1 and the internal space S2 of the sealing tube 22 where the cathode lead rod 52 is located communicate with each other.

As shown in FIG. 1, since the anode lead rod 51 supports the anode 3 having a large volume at the tip, the weight of the entire structure including the anode lead rod 51 and the anode 3 becomes heavy. The anode lead bar 51 is held by the holding cylinder 71 because it cannot be held.
On the other hand, since the cathode 4 has a smaller volume than the anode 3 and is light in weight, the structure including the cathode lead bar 52 and the cathode 4 can be supported only by the step glass 62.

The virtual surface A shown in FIG. 1 is a surface along the side surface 71a on the arc tube 1 side of the holding cylinder 71, and the virtual surface B is a boundary surface between the arc tube 1 and the sealing tube 22 on the cathode side. In other words, the inner wall of the arc tube 2 refers to the inner surface of the arc tube that exists between the virtual plane A and the virtual plane B.
The virtual surface C is a boundary surface between the sealing tube 22 and the step glass 62, and the inner wall of the sealing tube is a sealing tube existing between the virtual surface B and the virtual surface C. It refers to the inner surface.

In the lamp shown in FIG. 1, the area of the inner wall of the arc tube is 10380 mm ² , and the area of the inner wall of the sealing tube is 87400 mm ² .
In the present invention, in order to lower the temperature of the sealing tube as compared to the arc tube and to positively attach the evaporated material from the electrode to the inner wall of the sealing tube from the inner wall of the arc tube, the area of the inner wall of the arc tube is 4700mm ² ~10380mm range of ² well, good area range 3900 mm ² ～87400Mm ² of the inner wall of the sealing tube.

As a result, it is possible to utilize the property that the evaporated substance from the electrode adheres to the low temperature part, and the evaporated substance can be attached to the inner wall of the sealed 22 tube.
Further, the evaporated tungsten, which constitutes the electrode, particularly the anode, can be positively attached to the inner wall of the sealing tube 22 from the inner wall of the arc tube 1, and the blackening of the inner wall of the arc tube 1 is suppressed. Therefore, the light from the arc is not blocked by the blackened material, and even if the lamp is turned on for a long time, a decrease in light output can be suppressed.

The short arc type discharge lamp of the present invention is suitably applied to a lamp in which evaporation of tungsten constituting the anode is remarkable, and is suitably applied to a lamp having a rated current of 45 A or more.
Further, in order to lower the temperature of the cathode side sealing tube as compared with the arc tube, when the short arc type discharge lamp is vertically lit, it is necessary to arrange the cathode side sealing tube so as to be positioned below. is there.

As shown in FIG. 1, the short arc type discharge lamp of the present invention has a structure in which the cathode lead bar 52 is supported only by the step glass 62.
In such a structure, a load due to the dead weight of the cathode lead bar 52 and the cathode 4 is applied to the stepped glass 62, and depending on the magnitude of the load, the rising portion 622 of the stepped glass 62 may crack and break. .

Next, the relationship between the step glass and the load will be described.
FIG. 2 is an explanatory diagram for explaining a load applied to the cathode side joint glass.
As shown in FIG. 2, the step glass 62 has a structure having a sealing portion 621 sealed to the cathode lead rod 52 and a rising portion 622 rising so as to be separated from the cathode lead rod 52 following the sealing portion 621. It is.

The breakage of the step glass 62 is caused by a crack applied to the rising portion 622 due to a load applied to the rising portion 622. As shown in FIG. 2, the rising portion 622 has a shape having a certain range rather than a single point. It is difficult to uniquely determine the load applied to the rising portion 622.
For this reason, the intersection of the virtual line X passing through the rising portion 622 and the longitudinal axis Y passing through the center of the cathode lead bar 52 is P, and the distance from the intersection P to the tip of the cathode is L (mm). The relationship of L × W when the total weight W (gf) of the cathode lead on the cathode tip side and the cathode was obtained was obtained, and a condition for generating cracks at the rising portion 622 was derived from this L × W value.

  An experiment was conducted to examine the state of cracks generated at the rising portion of the stepped glass, using a structure having the following conditions.

<Structure>
Cathode 4: cathode outer diameter 10 mm, axial length 18 mm, material is triedet tungsten cathode lead bar 52: outer diameter 6 mm, material tungsten

  In the experiment, only the length of the cathode lead rod 52 was changed. As a result, the weight W (gf) of the entire structure of the cathode 4 and the cathode lead rod 52 existing from the intersection P to the tip of the cathode 4 and the intersection P The length L (mm) is changed up to the tip of the cathode 4.

The experimental results are shown in FIG.
In FIG. 3, if there is no crack in the rising part, “◯” is written in the damage status column, and if there is a crack in the rising part, “X” is written in the damage status column. Yes.
As shown in FIG. 3, when the value of L × W is less than 230 ×× 10 ³ (mm · gf), the column of damage status is “◯”, and it is understood that no crack is generated in the rising portion. .
On the other hand, if the value of L × W is 230 ×× 10 ³ (mm · gf) or more, the column of damage status is “×”, and it can be seen that cracks are generated in the rising portion.

That is, by setting the value of L × W to a range of less than 230 × 10 ³ (mm · gf), breakage of the stepped glass can be reliably prevented.

DESCRIPTION OF SYMBOLS 1 Light emission tube 21 Sealing tube 22 Sealing tube 3 Anode 4 Cathode 51 Anode lead bar 52 Cathode lead bar 61 Step glass 62 Step glass 611 Sealing part 612 Rising part

Claims (2)

In the short arc type discharge lamp in which the sealing tube following the arc tube, the anode lead rod and the cathode lead rod supporting the anode and the cathode disposed in the arc tube are sealed by the step glass in the sealing tube,
The anode lead rod is inserted and held in a holding cylinder, and the holding cylinder is supported at a narrowing portion of the sealing tube,
The cathode lead bar is supported only by the step glass,
A short arc type discharge lamp, wherein an inner space of the arc tube communicates with an inner space of the sealing tube in which the cathode lead bar is located. The joint glass sealed to the cathode lead rod has a sealing portion sealed to the cathode lead rod, and a rising portion that rises away from the cathode lead rod following the sealing portion,
Let P be the intersection of an imaginary line passing through the rising portion and a longitudinal axis passing through the center of the cathode lead rod,
When the distance from the intersection P to the cathode tip is L (mm), and the total weight W (gf) of the cathode lead and cathode on the cathode tip side from the intersection P,
L * W is less than 230 * 10 < ³ > (mm * gf), The short arc type discharge lamp of Claim 1 characterized by the above-mentioned.

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