Discharge lamp and lighting device

Abstract

A discharge lamp and a lighting device are provided, which can lower the temperature of a sealed tube, reduce the stress applied to the sealed tube, and prevent cracks. A discharge lamp, characterized in that the discharge lamp comprises: a discharge tube; a pair of sealed tubes connected to both sides of the discharge tube; and a cylindrical windshield member covering at least one sealed tube, wherein at least a portion of the windshield member is formed with a heat reflection suppression unit for suppressing the reflection of radiant heat from the sealed tube to the sealed tube.

Description

Technical Field

[0001] The present invention relates to a discharge lamp and a lighting device used in an exposure device, etc., and particularly to a short arc discharge lamp. Background Art

[0002] In short arc discharge lamps used in exposure devices, lighting devices, etc., during discharge, the electrode support rods and the like may become hot and overheat the sealed tube. As a result, cracks may occur at the joint between the metal part and the glass part in the sealed tube. In order to prevent overheating, cooling air is blown to the discharge lamp.

[0003] On the other hand, when the discharge tube is overcooled, mercury does not evaporate sufficiently in the period immediately after the lighting starts, and the luminous intensity is weak. In addition, by blowing the cooling wind directly to the sealed tube, a high temperature portion and a low temperature portion are generated, which causes thermal strain in the sealed tube. Therefore, in order to maintain the temperature of the sealed tube in an appropriate state from the start of lighting, a substantially cylindrical wind shield (appropriately referred to as a wind shield) is arranged to cover the sealed tube (for example, refer to Patent Document 1).

[0004] The wind shield must be precisely positioned, including the distance between the sealed tube and the wind shield, to control the flow of cooling air along the surface of the discharge tube and the sealed tube and appropriately maintain the temperature of the sealed tube. For example, in Patent Document 2, the wind shield is positioned at a predetermined position according to the shape of the lamp at the connection portion between the sealed tube and the discharge tube, so that only a part of the cooling air flows through the gap between the sealed tube and the wind shield, and the lamp is effectively cooled during the period from the start of lighting to the stable lighting state.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2001-135134

[0008] Patent Document 2: Japanese Patent Application Publication No. 2011-70833 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] However, the sealed tube cannot be maintained at an appropriate temperature simply by setting the position of the wind shield, and the sealed tube may become overheated. Therefore, it is necessary to prevent the discharge tube from being overcooled during the period from the start of lighting to the stable lighting state, and to prevent the sealed tube from being overheated during the continuous lighting period after stable lighting.

[0011] Therefore, an object of the present invention is to provide a discharge lamp and a lighting device capable of preventing overcooling of a discharge tube during a period from lighting start to a stable lighting state and preventing overheating of a sealed tube during a continuous lighting period after stable lighting.

[0012] Means used to solve problems

[0013] The present invention relates to a discharge lamp, characterized in that the discharge lamp comprises: a discharge tube; a pair of sealed tubes connected to both sides of the discharge tube; and a cylindrical windproof component covering at least one sealed tube, a heat reflection suppression unit being formed on at least a portion of the windproof component, the heat reflection suppression unit suppressing the reflection of radiant heat from the sealed tube toward the sealed tube.

[0014] In addition, the present invention relates to a lighting device, characterized in that the lighting device comprises: a discharge lamp, which has a discharge tube and a pair of sealed tubes connected to both sides of the discharge tube; and a cylindrical windproof component, which covers at least one sealed tube, and a heat reflection suppression unit is formed on at least a portion of the windproof component, and the heat reflection suppression unit suppresses the reflection of radiant heat from the sealed tube toward the sealed tube.

[0015] Effects of the Invention

[0016] According to at least one embodiment, a heat reflection suppression unit (aluminum oxide film treatment) is formed on the wind shield, the emissivity of the wind shield increases, and the heat from the sealed tube is absorbed (heat reflection is suppressed), so that the temperature of the sealed tube can be reduced. When the temperature of the sealed tube is lowered, the temperature of the metal parts in the sealed tube is reduced, and the metal parts expand, so that the force pressing the sealed tube is reduced, so the stress applied to the sealed tube is reduced, and cracks can be prevented. In addition, the effects described here are not necessarily restrictive, and can be any effect described in this specification or an effect different from them. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. 1 is a diagram schematically showing a short arc discharge lamp to which the present invention can be applied.

[0018] Figure 2 It is a cross-sectional view showing the structure of the cathode side according to one embodiment of the present invention.

[0019] Description of labels:

[0020] 10···discharge lamp, 11···discharge tube, 12a, 12b···sealed tube, 13a, 13b···lamp holder, 20···cathode, 30···anode, 31···glass tube, 32···glass member, 34···metal foil, 35, 36···metal ring (ring-shaped member), 40, 50···wind shield (wind shield member), 60, 70···heat-insulating film (film) DETAILED DESCRIPTION

[0021] An embodiment of the present invention will be described with reference to the drawings. Figure 1 1 is a diagram schematically showing an embodiment of a short arc discharge lamp. The short arc discharge lamp 10 is a discharge lamp that can be used as a light source of an exposure device for pattern formation, and has a discharge tube (light emitting tube) 11 made of transparent quartz glass. In the discharge tube 11, a cathode 20 and an anode 30 are arranged opposite to each other at a predetermined interval.

[0022] On both sides of the bulb-shaped discharge tube 11, quartz glass sealing tubes 12a and 12b are formed integrally with the discharge tube 11 in a manner opposed to each other, and lamp holders 13a and 13b are connected to both ends of the sealing tubes 12a and 12b. The lamp holders 13a and 13b are fixed to the sealing tubes 12a and 12b by, for example, a powder adhesive. The discharge lamp 10 is arranged in a manner such that the anode 30 is on the upper side and the cathode 20 is on the lower side in the vertical direction.

[0023] Conductive electrode support rods 14a and 14b are provided inside the sealed tubes 12a and 12b for supporting the metal cathode 20 and anode 30, and are connected to conductive lead rods through annular parts (metal rings) and metal foils such as molybdenum. The sealed tubes 12a and 12b are welded together with glass tubes and glass parts provided inside the sealed tubes 12a and 12b, thereby sealing the discharge space enclosed with mercury and rare gas. The lead rods are connected to an external power supply unit, and a voltage is applied between the cathode 20 and the anode 30 through the metal rings, metal foils, and electrode support rods 14a and 14b. When power is supplied to the discharge lamp 10, arc discharge occurs between the electrodes, and bright lines (ultraviolet rays) generated by mercury are emitted.

[0024] In addition, a reflector (condenser) (not shown) in the form of a rotating ellipsoid is arranged around the discharge lamp 10 to form a lighting device. When the lamp is turned on, the light emitted from the discharge lamp 10 is reflected by the reflector. The reflected light converges at a secondary focus and is guided to an irradiated object via an illumination optical system (not shown) or the like. For example, when the lighting device is arranged in an exposure device, light is irradiated onto the photosensitive surface of the substrate. Furthermore, cooling nozzles are respectively arranged on the sealed tube 12a side and the sealed tube 12b side of the discharge lamp 10, and the sealed tube 12a and the lamp holder 13a, and the sealed tube 12b and the lamp holder 13b are respectively cooled by cold air from the cooling nozzle while the lamp is turned on.

[0025] The wind shields 40 and 50, which are wind shield components of a cylindrical thin plate, are metal cylindrical components (here, aluminum) that surround the sealed tubes 12a and 12b and extend to the ends of the lamp holders 13a and 13b, and are respectively screwed to the lamp holders 13a and 13b. For example, the wind shields 40 and 50 are formed by combining a pair of semi-cylinders with each other. Through the wind shields 40 and 50, the cold air from the cooling nozzles will not directly blow to the sealed tubes 12a and 12b, thereby preventing overcooling from the start of lighting to the stable lighting, and making the temperature of the sealed tubes 12a and 12b during stable lighting within an appropriate range. As described below, a heat reflection suppression unit for suppressing the reflection of radiant heat from the sealed tubes 12a and 12b to the sealed tubes is formed in at least a portion of the wind shields 40 and 50.

[0026] Thermal insulation films 60 and 70 are formed on the outer surface of the interface portion between the discharge tube 11 and the sealing tubes 12a and 12b. The thermal insulation films 60 and 70 are provided to maintain the coldest point temperature high during lighting.

[0027] Figure 2 The sectional view is a more detailed view of the structure including the sealing tube 12a and the lamp holder 13a on the cathode 20 side. The discharge tube 11 and the sealing tube 12a are formed integrally, and the shape changes from the periphery of the interface with the sealing tube 12a so that the diameter increases from the sealing tube 12a toward the discharge tube 11.

[0028] The electrode support rod 14a is inserted through the hollow thick-walled glass tube 31 and the inner metal ring 35 as an annular member, and then extends to the cylindrical glass member 32 and is inserted through the glass member 32. The electrode support rod 14a is held along the lamp axis by the glass tube 31, the metal ring 35, and the glass member 32. The glass tube 31, the glass member 32 and the inner surface of the sealing tube 12a are welded together.

[0029] In addition, the inner metal ring 35 is provided between the glass tube 31 and the glass member 32, and the outer metal ring 36 as a ring-shaped member is provided between the glass member 32 and the outer glass tube 37. In addition, a disk-shaped circular plate foil (not shown) can be provided between each member such as between the glass tube 31 and the inner metal ring 35, between the glass member 32 and the outer metal ring 36. The lead rod 33 is inserted through the outer metal ring 36 and inserted into the sealed end side of the glass member 32. On the peripheral surface of the glass member 32, a plurality of strip-shaped metal foils 34 made of molybdenum or the like are provided separately from each other along the circumferential direction, and both ends thereof are connected to the metal rings 35 and 36.

[0030] A rolled foil (not shown) wound in a cylindrical shape may be provided on the outer peripheral surface of the inner metal ring 35 to cover the electrode-side end of the metal foil 34 together with the inner metal ring 35. The surface of the rolled foil may be embossed.

[0031] A heat-insulating film 60 made of a film (metal film) containing platinum, gold, or the like is formed (applied) on the entire outer surface of the sealing tube 12a from the axial end of the discharge tube 11 so as to cover the entire outer surface thereof. In addition, a region S on which the heat-insulating film is not formed is formed on at least a portion of the region of the outer surface of the sealing tube 12a that faces the glass tube 31 located in the sealing tube 12a. The heat-insulating film 60a is formed separately from the lower side (here, the lamp holder 13a side) of the region S. The heat-insulating film 60a is formed on the entire surface of the sealing tube 12a in the region facing the metal ring 35. In addition, the heat-insulating films 60 and 60a are formed of thin films, but their thickness is shown exaggerated for the sake of explanation.

[0032] The wind shield 40 coaxially extends from the lamp holder 13a to a position below (on the opposite side) the end of the glass tube 31 on the discharge tube 11 side, and is arranged concentrically with the outer surface of the sealed tube 12a with a predetermined interval. An opposing gap is formed on the inner surface of the wind shield 40, and an opening 41 is formed at the end on the opposite side to the sealed end. The position of the end of the wind shield 40 on the discharge tube 11 side is included in the range opposite to the above-mentioned area S where the heat-insulating film 60 is not formed. For example, the opening 41 is located near the axial middle position of the glass tube 31. That is, the length of the wind shield 40 is shorter than that of the conventional structure extending to the end of the glass tube 31 on the discharge tube side.

[0033] For example, in the case of a wind shield made of metal such as aluminum, the heat (radiant heat) from the sealed tube is reflected by the inner surface of the wind shield, which may cause the sealed tube to become overheated. Therefore, in one embodiment of the present invention, the wind shield 40 is treated with an alumite film to reduce the heat reflected toward the sealed tube 12a. The alumite film treatment forms an oxide film on the surface to absorb the incident heat, which can reduce the heat returned to the sealed tube 12a. In addition, as a heat reflection suppression unit, in addition to the alumite film treatment, a treatment that suppresses reflected heat can also be used. For example, a surface processing based on a mechanical treatment such as sandblasting, a coating system that adheres so-called radiation paint and heat dissipation paint, and a structure that adheres a thin plate or plate of ceramics can be used. Since the wind shield can be made of a material other than aluminum, it can be appropriately selected according to the material of the wind shield. In addition, the unit that absorbs the radiant heat from the sealed tube 12a can be at least provided on the surface (inner surface) of the wind shield 40 that is opposite to the sealed tube 12a, or it can be a structure provided on at least a part of the inner surface.

[0034] The overheating of the sealed tube can be prevented by the associated wind shield 40, thereby lowering the temperature of the sealed tube. When the temperature of the sealed tube 12a is lowered, the temperature of the metal component (inner metal ring 35) in the sealed tube 12a is lowered, and the force (expansion amount) of the metal ring 35 pressing the foil wound on the metal foil 34 or the outer peripheral surface of the metal ring 35 is reduced, so the stress applied to the sealed tube 12a is reduced, and cracks in the sealed tube 12a can be prevented.

[0035] In the present embodiment, a region S where no heat-insulating film is formed is provided on a portion of the outer surface of the sealing tube 12a in the region opposite to the glass tube 31. Thus, the heat of the electrode support rod 14a inserted into the glass tube 31 can be released without being blocked by the heat-insulating film, and as a result, the temperature of the inner metal ring 35 connected to the electrode support rod 14a can be reduced. As the temperature of the metal ring 35 is reduced, the metal ring 35 expands, thereby reducing the force (expansion amount) pressing the foil rolled on the outer circumference of the metal foil 34 or the metal ring 35, and the stress applied to the sealing tube 12a is also reduced, so that cracks in the sealing tube 12a can be prevented. On the other hand, the heat-insulating film 60a is formed on the entire region of the surface of the sealing tube 12a opposite to the inner metal ring 35. Thus, the temperature of the sealing tube can be set in an appropriate temperature range.

[0036] In addition, by shortening the length of the wind shield 40, the area receiving the heat from the sealed tube 12a and the area reflecting the heat to the sealed tube 12a are reduced, so that the temperature of the sealed tube can be reduced. In particular, the end of the wind shield 40 is located in the range opposite to the area S where the thermal insulation film 60 is not formed, so that the heat (radiant heat) released from the sealed tube 12a can be released without being blocked by the thermal insulation film and the wind shield 40, thereby promoting the temperature reduction of the electrode support rod 14a and the inner metal ring 35. In addition, one or more ventilation holes can be partially provided on the surface of the wind shield 40. Furthermore, the diameter of the wind shield 40 may not be constant in the longitudinal direction, and the diameter may change in the middle (for example, in a "convex" shape), or the diameter may gradually change into a conical shape. In addition, the wind shield 40 is composed of a pair of semi-cylinders combined with each other, and a gap may be formed in the combined part.

[0037] Under high temperature conditions, alkali ions reduce the adhesion between the metal foil 34 and the quartz glass, which may cause the metal foil 34 to peel off. However, according to the present embodiment, the foil peeling can be prevented by lowering the temperature of the sealing tube.

[0038] As described above, in one embodiment of the present invention, by performing a process to reduce the heat reflected from the inner surface of the wind shield toward the sealed tube, a region S without a heat-insulating film is formed, and the length of the wind shield in the longitudinal direction is shortened, so that these effects cooperate and the temperature of the electrode support rod and the metal ring can be reduced. In addition, the present invention can exert its effect regardless of the lamp shape of the interface portion between the sealed tube and the discharge tube.

[0039] In addition, the sealing tube 12b, lamp holder 13b, wind shield 50, heat-insulating film 70, etc. on the anode 30 side are configured similarly to the above-mentioned structure on the cathode 20 side. However, the above-mentioned structure for lowering the temperature of the sealing tube may be provided on at least one of the cathode 20 side and the anode 30 side. Furthermore, a part of the process of reducing the heat reflected from the inner surface of the wind shield to the sealing tube, forming the area S without the heat-insulating film, and shortening the length of the wind shield in the longitudinal direction may be used as the structure on the single electrode side.

[0040] The following table shows the experimental results. A discharge lamp having a structure according to an embodiment of the present invention was lit at 10.5 kW, and the temperature of the outer surface of the sealed tube 12a in the area opposite to the metal foil 34 (corresponding to the middle part of the sealed tube 12a. In Table 1, it is indicated as "sealed tube") and the outer surface of the sealed tube in the area opposite to the inner metal ring 35 (in Table 1, it is indicated as "metal ring") were measured. A thermocouple was used for the temperature measurement. As a comparative example (existing example), a short arc discharge lamp was used, which had a length extending to the end of the discharge tube side of the glass tube, was equipped with a wind shield without a heat reflection suppression unit, and had a heat insulation film formed on the outer surface of the sealed tube in the area opposite to the glass tube. In the comparative example, it was also lit at 10.5 kW, and the temperature was measured using a thermocouple.

[0041]

Table 1

[0042] Comparative Example [℃] The present invention [℃] Sealing tube 575.89 425.65 Metal ring 640.68 486.74

[0043] As shown in Table 1, according to the discharge lamp of one embodiment of the present invention, it was confirmed that the temperature dropped at both measurement positions (sealing tube and metal ring). This can prevent cracks in the sealing tube and peeling of the foil.

[0044] An embodiment of the present technology has been specifically described above, but the present invention is not limited to the above-mentioned embodiment, and various modifications based on the technical idea of ​​the present invention can be made. For example, in the above-mentioned embodiment, a heat reflection suppression unit is formed in the windproof component, but it does not necessarily need to be formed in the windproof component. The heat reflection suppression unit can also be formed in a tubular component different from the windproof component, or the tubular component can be formed by a material that absorbs heat. In addition, the structures, methods, steps, shapes, materials, and numerical values ​​listed in the above-mentioned embodiments are always just examples, and different structures, methods, steps, shapes, materials, and numerical values ​​can be used as needed.

Claims

1. A discharge lamp, characterized in that The discharge lamp has: Discharge tube; a pair of sealing tubes connected to both sides of the discharge tube; and a cylindrical windproof member covering at least one of the sealing tubes, A heat reflection suppression unit is formed on at least a portion of the windshield member, the heat reflection suppression unit suppressing the radiant heat from the sealed tube from being reflected toward the sealed tube. The sealed tube has: a conductive electrode support rod; a glass tube that holds the electrode support rod and is welded to the sealed tube; and a conductive annular component that is connected to the electrode support rod and electrically connects the metal foil arranged along the axial direction to the electrode support rod. A heat-insulating film is formed on the surface of the sealing tube in a region facing the annular member, and the heat-insulating film is not formed on at least a portion of a region facing the glass tube.

2. The discharge lamp according to claim 1, characterized in that The heat reflection suppression unit is formed at least on a surface of the windshield member that faces the sealing tube.

3. The discharge lamp according to claim 1 or 2, characterized in that The heat reflection suppressing unit is formed using an aluminum oxide film.

4. The discharge lamp according to claim 1, characterized in that The end of the wind shielding member is located on the side opposite to the end of the glass tube on the discharge tube side.

5. The discharge lamp according to claim 4, characterized in that The end portion of the windshield member is located in a range where the film is not formed in a region facing the glass tube.

6. A lighting device, characterized in that: The lighting device comprises the discharge lamp according to claim 1 .

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