CN101964296A - Short arc discharge lamp - Google Patents

Abstract

The invention provides a kind of short arc discharge lamp, it disposes an antianode and negative electrode relatively in luminous tube, following electrode structure is provided: particularly under repeating rated power light a lamp usually and with the standby that the power littler than rated power is lit a lamp light a lamp fully loaded/when standby is lit a lamp, anode front end central portion also can be more outstanding than its peripheral annular portion, do not produce the blackening of the lamp that the evaporation of electrode material causes.It is characterized in that, be formed with recess, in this recess, be inserted with, between the rearward end of this insertion body and described recess, be formed with the space by the insertion body that constitutes with this anode identical materials at the front end face of anode.

Description

Short arc discharge lamp

Technical field

The present invention relates to short arc discharge lamp, particularly relate to the exposure light source that is applicable to semiconductor, liquid crystal manufacturing field etc., the short arc discharge lamp with light source backlight of projector.

Background technology

Based on relatively the front end of the pair of electrodes of configuration distance is short and be similar to the point-source of light this point in luminous tube, short arc discharge lamp is by making up with optical system, as exposure device with or the light source of the usefulness backlight of projector.

Japanese kokai publication hei 10-188890 communique discloses existing short arc discharge lamp.

This existing short arc discharge lamp of expression among Fig. 4, the luminous tube 10 of short arc discharge lamp 1 possesses the sealing portion 12 that forms roughly spherical illuminating part 11 and two ends thereof that is positioned at central authorities.In luminous tube 10, the relative toward each other configuration of negative electrode 21 that constitutes by tungsten etc. with anode 31, and enclosing in the emitting space S of inside has luminescent substances such as mercury, xenon.

Be connected with above-mentioned negative electrode 21 and anode 31 electrode axis 22,32 that is provided with via not shown metal forming by 12 sealing of sealing portion.

But, in recent years, in the above-mentioned short arc discharge lamp that in the manufacturing process of semiconductor, liquid crystal panel, uses, as TOHKEMY 2000-181075 communique is pointed, in order to economize electrification, usually is not to light a lamp, but adopts the following mode of lighting a lamp (hereinafter referred to as " fully loaded/standby is lit a lamp ") with constant power: only when exposure, light a lamp (lighting a lamp usually) with rated power, when standbies such as substrate moves with the minimal power littler light a lamp (standby is lit a lamp) than described rated power.

Repeat for example following operation: when exposure, lit a lamp 0.1～10 second, when standby, lit a lamp 0.1～100 second with the standby power littler than rated power with rated power.

But, the lighting a lamp of lamp/when turning off the light or above-mentioned fully loaded/during input power change when standby is lit a lamp etc., because the heat flux that flows into anode from electric arc changes, so temperature of anode changes, and produces internal stress at anode.

At this moment, shown in Fig. 5 (A), (B), the central portion 50 of facing the anode front end face of electric arc is variations in temperature the best parts, so thermal expansion is also bigger.Relative therewith, it is less that the peripheral annular portion 51 of this central portion 50 compares described central portion 50 variations in temperature, and its thermal expansion is also less.

Therefore, central portion 50 is compressed stress owing to this thermal expansion from its peripheral annular portion 51, and its result can be to be out of shape from the outstanding mode of front end face.

Behind the temperature stabilization of anode front end, this giving prominence to can fully not reset into original shape yet, and can be residual when specified lighting a lamp.And, particularly be fully loaded with/when standby was lit a lamp, this distortion repeated to produce, and is outstanding owing to being accumulated the hypertrophyization that becomes.

So discharge is concentrated at the protuberance of hypertrophyization, this protuberance is overheated unusually, and the electrode substance evaporation also is attached to the luminous tube inwall, and there is the problem that causes that illumination descends rapidly in this luminous tube inwall blackening.

Patent documentation 1 Japanese kokai publication hei 10-188890 communique

Patent documentation 2 TOHKEMY 2000-181075 communiques

Summary of the invention

The problem that the present invention will solve is, in view of above-mentioned prior art problems, providing a kind of is particularly adopting fully loaded/standby to light a lamp in the short arc discharge lamp of mode, have and to relax the thermal stress that produces at the anode front end, the middle body that prevents the anode front end deforms, thereby prevents the short arc discharge lamp of the anode structure of blackening.

In order to solve above-mentioned problem, short arc discharge lamp of the present invention is characterised in that, front end face at described anode is formed with recess, is inserted with in this recess by the insertion body that constitutes with this anode identical materials, is formed with the space between the rearward end of this insertion body and described recess.

In addition, it is characterized in that at least a portion in described space is present in the scope from the anode front end to thermal diffusion length.

And then, it is characterized in that to establish distance from the anode front end face to the space be L, establish maximum secting area with respect to the space on the vertical cross-section of electrode axis when being S, described space is at S≤π L ²Scope.

According to short arc discharge lamp of the present invention, be inserted with in the recess that on the front end of anode, forms by the insertion body that constitutes with described anode identical materials, between the rearward end of this insertion body and described recess, be formed with the space, therefore, even particularly under the fully loaded/temperature of anode leading section changes when standby is lit a lamp etc. situation, its thermal change is because also directly transmission rearward point-blank of the existence in space, in addition, the effect of allowing the strain relief zone of inserting the body heat expansion is played in this space, suppresses the anode front end, promptly to insert body outstanding and be out of shape.Consequently, can prevent the blackening of the luminous tube that the evaporation of electrode causes, and prevent the decline of illumination sustainment rate.

Description of drawings

Fig. 1 is the part sectioned view of leading section of the anode of short arc discharge lamp of the present invention.

Fig. 2 is the part sectioned view of other execution modes.

Fig. 3 is the part sectioned view of other other execution modes.

Fig. 4 is the overall diagram of prior art.

Fig. 5 is the major part key diagram of Fig. 4.

Fig. 6 is relatively the present invention and an existing anode of expression, the illumination sustainment rate based on embodiment 1 has been carried out the table of the result of the test of some lantern test.

Embodiment

Fig. 1 represents the 1st execution mode, (A) is the profile that group is gone into part, (B) is the key diagram that group is gone into operation.

In the drawings, on the front end of the anode 3 that constitutes by tungsten etc., be formed with recess 4 in this front end face 3A upper shed.And, on this recess 4, inserting by the insertion body 5 that makes by constituting with anode 3 same materials such as being pressed into, the front end face 3A of its front end face and described anode 3 becomes same plane.

Between the rearward end of this insertion body 5 that inserts like this and recess 4, be formed with space 6.

In Fig. 1 (A), the position in the space 6 that forms in described recess 4 is L shaped to be become its part at least and is positioned at scope from front end face 3A to thermal diffusion length.

So-called thermal diffusion length is heat (temperature) that expression is given with the exchanging index that its wavelength is residual when spread till where arriving in material, definite by following formula.

$L=\sqrt{\mathrm{\α}/f}$

L: thermal diffusion length (m)

α: thermal diffusivity (m ²/ s)

F: repetition rate (Hz)

Herein, thermal diffusivity α is by to give a definition.

α＝k/(ρ×Cp)

K: the situation of pyroconductivity 120 (J/smK) ※ tungsten W

ρ: density 19.1 * 10 ³(kg/m ³) situation of ※ W

Cp: the situation of specific heat 134.4 (J/kgK) ※ W

Herein, if an example is shown, anode 3 is made of tungsten (W),

During repetition rate f=1 (Hz), L=6.84mm

During f=1000 (Hz), L=0.216mm

From the heat of anode 3 front ends, can only expect the thermal effect of direct current in the zone that exceeds above-mentioned scope, on this zone, can not express periodic variations in temperature.That is, in other words,, compare thermal strain with other parts and be easy to accumulate, consequently on electrode, produce irreversible distortion lighting a lamp and be subjected in the zone of periodic temperature change because of fully loaded/standby.

But, because the existence in the space that forms in anode hindered from the rearward heat conduction of anode front end, be difficult to produce temperature difference in the zone at the rear in this space and become roughly even, therefore the thermal strain based on thermal expansion difference diminishes.

On the other hand, though produce thermal expansion at the anode front end, above-mentioned space self has been played and has been allowed in freely the expand effect in the strain relief zone of shrinking of electrode interior, has therefore consequently suppressed the distortion of electrode.

That is, though produced compression stress corresponding to thermal expansion at the electrode front end, this compression stress discharges in the space side, therefore can suppress the distortion towards the electrode front end.

But, on the other hand,, then diminish from the heat conducting sectional area of electrode front end towards rearward end if described space is excessive, cause near the temperature of electrode front end to rise, therefore can promote the evaporation of electrode material, consequently cause the decline of illumination sustainment rate.

Therefore, the size in described space 6 is preferably as follows formation: establish its cross-sectional area, promptly establish when being S with respect to the maximum secting area on the vertical cross-section of electrode axis, satisfy S≤π L ²Relation.

Fig. 2 is the part sectioned view of the 2nd execution mode, (A) is that group is gone into profile, (B) is the key diagram that group is gone into operation.

In this embodiment, recess 4 is made of two opening 4A, 4B.The first opening 4A is roughly the same with the diameter that inserts body 5, and portion is formed with diameter than its second little opening 4B within it.

Insert body 5 and be pressed into the first opening 4A, and determine the degree of depth by the second opening 4B.Then, this second opening 4B forms space 6.

Fig. 3 is the part sectioned view of the 3rd execution mode, (A) is that group is gone into profile, (B) is that group is gone into key diagram.

In this embodiment, the outstanding flange 5A that is formed with ring-type is formed with circular recess 5B at rear end face in the rear end of inserting body 5.When this insertion body 5 is pressed into recess 4, the bottom surface butt of collar flange 5A and recess 4, described recess 5B forms space 6.

According to above-mentioned Fig. 2 and two execution modes shown in Figure 3, when inserting body 5 and insert recesses 4 and the bottom butt of this recess 4 and automatically form space 6.

In order to compare the present invention and existing anode, the illumination sustainment rate based on embodiment 1 has been carried out the some lantern test.

The inclosure amount of mercury of the lamp of experiment usefulness is 2mg/cc, and Ar is about 3.5 air pressure, and anode (tungsten) is of a size of: diameter: 29mm, total length: 50mm, point diameter: 10mm.The diameter of negative electrode: 12mm, taper angle: 60 degree, point diameter: 1mm, the interpolar before lighting a lamp: 6.5mm.

And, prepare three kinds of anodes for this test, wherein, anode of the present invention forms the recess 4 of diameter 3.5mm, degree of depth 10mm on the front end face of above-mentioned anode, is pressed into the insertion body 5 of diameter 3.5mm, thickness 8mm in this recess 4.Consequently, between the bottom of inserting body 5 and recess 4, be formed with the space 6 of height 2mm.

In addition, product as a comparison, the thickness of preparing to make above-mentioned insertion body is identical with concave depth and be pressed in this recess, do not have an anode in space.And, as existing product, prepare the anode that does not carry out above-mentioned shaping.

For these lamps, make that lighting current 50A and 140A switch every 1 second (0.5Hz), as to apply rapid input modulation amplitude periodic heat load respectively and in the accelerated test of short time (100 hours) inner evaluation illumination sustainment rate.In addition, the ultraviolet illumination of the wavelength 365nm (i line) when the illumination sustainment rate begins with lighting a lamp under the same condition of lighting a lamp is benchmark, calculates the illumination sustainment rate after 100 hours.

These result of the tests are illustrated among Fig. 6.

As can be seen from Figure 6, for existing product, the front end central portion of anode is distortion sharply with bloating, its front end fusion.Owing to there is the danger of breaking, the some lantern test interrupts halfway.Illumination sustainment rate in this moment is 52%.

For comparative example, the insertion body that is pressed into is out of shape with bloating, its leading section protuberance, and the illumination sustainment rate is 65%.

Relative therewith, in the present invention, the distortion of insertion body that is formed at the front end central portion is few, and the illumination sustainment rate is also good, is 85%.

As described above, short arc discharge lamp of the present invention, in the recess that on the front end of anode, forms, insertion is by the insertion body that constitutes with the anode identical materials, between the bottom of the rearward end of this insertion body and described recess, be formed with the space, therefore, even particularly adopting fully loaded/standby to light a lamp under the situation of mode, also can obtain following effect: when the central portion of anode front end is periodically heated, its thermal strain discharges in described space, do not produce thus towards front end and outstanding partly distortion, can suppress the illumination that blackening caused that the evaporation because of anode material causes and descend.

Claims (3)

1. a short arc discharge lamp disposes an antianode and negative electrode relatively in luminous tube, it is characterized in that,

Front end face at described anode is formed with recess, is inserted with in this recess by the insertion body that constitutes with this anode identical materials, is formed with the space between the rearward end of this insertion body and described recess.

2. short arc discharge lamp as claimed in claim 1 is characterized in that, at least a portion in described space is present in the scope from the anode front end to thermal diffusion length.

3. short arc discharge lamp as claimed in claim 1 or 2 is characterized in that, to establish distance from the anode front end face to the space be L, establish maximum secting area with respect to the space on the vertical cross-section of electrode axis when being S, and described space is at S≤π L ²Scope.

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