JP2017068954A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp for suppressing an electrode from blackening due to wearing.SOLUTION: A discharge lamp 1 includes: an airtight container 10 through which ultraviolet rays transmit and in which sealing parts 14, 14 are formed in a discharge space 12 and at both ends of the discharge space 12; rare gas and mercury which are sealed inside of the discharge space 12; and a pair of discharge electrodes 20, 20 whose parts are embedded in the sealing parts 14, 14, in which coils 24 are wound around shaft parts and which has shaft members 22 whose tip smaller than the outer diameter than the shaft part is provided in the discharge space 12. When the outer diameter of the shaft part 22 is A(mm) and the outer diameter of the tip is B(mm), the shaft member satisfies both 1.5≤A≤3.0 and B/A≤0.80.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a discharge lamp.

  For example, a discharge lamp is disclosed as a light source used in applications such as exposure, curing, and drying by irradiating an object with ultraviolet rays in the field of liquid crystal panel production and printing.

JP 2009-259790 A

  If the discharge lamp is left in a dark place for a long time, the initial electrons are not supplied by excitation of natural light, and the time until dielectric breakdown is prolonged, or the start-up failure of the discharge lamp is caused. To solve this problem, there is a method of applying an emitter material having a low work function to a coil wound around the discharge electrode of a discharge lamp. There is a concern that the location where the emitter and the hermetic container react with each other becomes hot, leading to blackening of the hermetic container.

  In recent years, there has been an increasing demand for high-power discharge lamps for printing. In high-power lamps, there is a tendency to increase the electrode diameter in order to suppress electrode wear during lighting. However, when the electrode diameter increases, the electrode temperature hardly rises during initial start-up, and the electrode wears out, resulting in blackening. There's a problem.

  Further, as a discharge lighting method, for example, when there is an object to be irradiated with ultraviolet rays, power called rated power is supplied to the discharge lamp in order to emit a desired amount of ultraviolet rays. On the other hand, when there is no object to be irradiated, so-called dimming, in which the power supplied to the discharge lamp is set to the rated power or less, may be performed. When dimming is performed, the electrode is further worn out in an attempt to increase the number of electrons emitted from the electrode in order to maintain arc discharge inside the discharge lamp.

  Embodiments of the present invention provide a discharge lamp that suppresses blackening due to electrode wear.

  According to an embodiment of the present invention, an airtight container that transmits ultraviolet rays and has a discharge space and sealing portions formed at both ends of the discharge space, a rare gas and mercury enclosed in the discharge space, A pair of discharges having a shaft member provided with a part embedded in the sealing portion, a coil wound around the shaft portion, and a tip portion having an outer diameter smaller than that of the shaft portion provided in the discharge space An electrode. The shaft material satisfies both 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80 when the outer diameter of the shaft portion is A (mm) and the outer diameter of the tip portion is B (mm). .

  According to the embodiment of the present invention, it is possible to provide a discharge lamp that suppresses blackening due to electrode wear.

FIG. 1 is a schematic view illustrating a discharge lamp according to the first embodiment. FIG. 2 is an enlarged schematic view of the shaft member 22 of the discharge lamp 1 according to the first embodiment. FIG. 3 shows the discharge lamp 1 according to the first embodiment. The outer diameter A of the shaft portion of the tip portion 221 and the B / A represented by the outer diameter A of the shaft portion and the outer diameter B of the tip portion. It is a figure which shows the result of the blackening presence or absence by a difference. FIG. 4 is a view showing the tip 223 of the shaft member 22 of the discharge lamp 1 according to the first embodiment. FIG. 5 is a schematic view illustrating Modification Example 1 of the discharge lamp 1 according to the first embodiment. FIG. 6 is a schematic view illustrating Modification Example 2 of the discharge lamp 1 according to the first embodiment. FIG. 7 is a schematic view illustrating Modification Example 3 of the discharge lamp 1 according to the first embodiment.

  A discharge lamp 1 according to an embodiment described below includes an airtight container 10 that transmits ultraviolet rays and has sealing portions 14 and 14 formed at both ends of the discharge space 12 and the discharge space 12; A rare gas and mercury to be sealed; a part is embedded in the sealing portions 14 and 14, a coil is wound around the shaft portion, and a tip portion 221 having an outer diameter smaller than that of the shaft portion 222 is discharged. A pair of discharge electrodes 20 and 20 each having a shaft member 22 provided in the space 12. The shaft material has both 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80 when the outer diameter of the shaft portion 222 is A (mm) and the outer diameter of the tip portion 221 is B (mm). Meet.

  According to this embodiment, it is possible to provide a discharge lamp that suppresses blackening due to electrode wear.

  Moreover, in the discharge lamp 1 which concerns on embodiment described below, the front-end | tip part 221 has the point 223. FIG.

  According to the present embodiment, it is possible to provide a discharge lamp that suppresses the instability of arc discharge.

  Further, in the discharge lamp 1 according to the embodiment described below, the shaft member 22 and the coil 24 are impregnated with an emitter, and the emitter is any one of thorium oxide, hafnium carbide, and zirconium carbide at 0.50 to 0.50. Contains 2.0 wt%.

  According to this embodiment, it is possible to provide a discharge lamp that suppresses blackening due to electrode wear.

  Embodiments of the present invention will be described below with reference to the drawings.

  (First embodiment)

  FIG. 1 illustrates a discharge lamp 1 according to a first embodiment with reference to FIG. FIG. 1 illustrates a discharge lamp 1.

  As shown in FIG. 1, the discharge lamp 1 according to the present embodiment includes an airtight container 10 and a pair of discharge electrodes 20 and 20.

  In the present embodiment, an embodiment using a high-pressure mercury lamp as the discharge lamp 1 is illustrated.

  The airtight container 10 is formed in a straight tube shape and has a discharge space 12 therein. Moreover, the sealing part 14 and 14 are formed in the both ends of an airtight container, and the discharge space 12 is kept airtight. The airtight container 10 is made of a material that transmits ultraviolet rays, and is made of, for example, quartz glass. The hermetic container 10 has an outer diameter of 23 mm and a light emission length (distance between the discharge electrodes 20-20) of 375 mm.

  In the discharge space 12, mercury or a rare gas (not shown) enclosed in the discharge space 12 emits light when electric power is applied from the pair of discharge electrodes 20 and 20. For example, the discharge space 12 has an inner diameter of 20 mm and a light emission length of 375 mm.

Mercury is enclosed in the discharge space 12 and emits ultraviolet rays of 254 nm and 365 nm, for example, when electric power is applied from the outside of the discharge lamp 1. The amount of mercury enclosed is expressed by the amount of enclosure per unit volume (1-5 mg / cm ³ ) obtained by dividing the actual dormitory of mercury by the volume of the discharge space 12, that is, the airtight container 10, for example, 1-5 mg. / Cm ³ . The composition of mercury is not limited to the above, and may be composed of, for example, amalgam in which a metal is mixed with mercury.

  The rare gas promotes discharge when starting the discharge lamp 1 and contributes to maintaining the discharge after the start of discharge. The enclosure pressure of the rare gas is, for example, 0.67 kPa to 5.3 kPa. The rare gas may be any one of xenon, argon, neon, or a mixed gas of two or more.

  The sealing portions 14 and 14 are formed at both ends of the discharge space 12. The sealing portions 14 and 14 are made of the same quartz glass as the airtight container 10. The sealing portions 14 and 14 are formed by so-called shrink seals in which the electrodes 20 and 20 are provided at desired positions and then melted and sealed by a melting means such as a gas burner (not shown) under reduced pressure. The sealing portions 14 and 14 may be made of quartz glass or the like different from the airtight container 10. Moreover, the sealing parts 14 and 14 may be formed by what is called a pinch seal by forming means such as a pincher (not shown). The length of the sealing parts 14 and 14 is 25 mm.

  The pair of discharge electrodes 20, 20 introduces electric power applied from the outside of the discharge lamp 1 into the discharge space 12 and causes arc discharge in the discharge space 12. The pair of discharge electrodes 20, 20 are partly embedded in the sealing portions 14, 14 and are provided opposite to both end portions of the discharge space 12. The pair of discharge electrodes 20 and 20 includes shaft members 22 and 22, coils 24 and 24, foils 26 and 26, and outer leads 28 and 28.

  The shaft members 22 and 22 apply electric power to the discharge space 12. The electrode rods 22 and 22 are configured such that one end protrudes into the discharge space 12 and the other end is embedded in the sealing portions 14 and 14. In addition, coils 24 and 24 are provided at one ends of the shaft members 22 and 22 that protrude toward the discharge space 12. The shaft members 22 and 22 are connected to the foils 26 and 26 by welding at the other end. The shaft members 22, 22 are made of tungsten, for example.

  The coils 24, 24 are provided on one end side of the shaft members 22, 22, and the temperature of the shaft members 22, 22 is suppressed by radiating temperature from the tips of the shaft members 22, 22 being discharged. The coils 24, 24 have one end provided on one end side of the shaft members 22, 22, that is, on the discharge space 12 side, and the other end provided on the other end side of the shaft members 22, 22. The coils 24, 24 are made of, for example, tungsten.

  The foils 26 and 26 are embedded and sealed in the sealing portions 14 and 14 to keep the airtight container 10 airtight. One end of the foils 26, 26 is welded to the other end of the shaft members 22, 22, and the other end is welded to one end of the outer leads 28, 28, and is embedded in the sealing portions 14, 14. The foils 26 and 26 are made of, for example, molybdenum.

  The outer leads 28, 28 are partially embedded in the sealing portions 14, 14, and electrically connect the inside of the airtight container 10 and the lead wires 40, 40 partially provided inside the bases 30, 30. Connecting. One end of the outer leads 28 and 28 is welded to the foils 26 and 26, and the other end is connected to the lead wires 40 and 40. The outer leads 28, 28 are made of, for example, molybdenum.

  The bases 30 and 30 are partially provided on the outer periphery of the sealing portions 14 and 14, the outer leads 28 and 28 and the lead wires 40 and 40 of the hermetic container 10, and the connection points of the outer leads 28 and 28 and the lead wires 40 and 40 are Prevents exposure. The bases 30 and 30 are made of ceramics, for example. Moreover, in order to make the fitting with the airtight container 10 stronger in the bases 30 and 30, for example, cement (not shown) may be fixed to the sealing portions 14 and 14.

  The lead wire 40 electrically connects the inside of the airtight container 10 and a power supply circuit (not shown). One end of the lead wires 40, 40 is connected to the other end of the outer leads 28, 28, and the other end is connected to a power supply circuit or the like. The lead wires 40, 40 are made of, for example, an annealed copper wire. Note that terminals 50 and 50 may be provided at the other ends of the lead wires 40 and 40 in order to facilitate connection to the power supply circuit.

  Here, the shaft member 22 and the coil 24 will be described in more detail with reference to FIG. FIG. 2 is an enlarged view of the shaft member 22 and the coil 24.

  The shaft member 22 has a tip portion 221 and a shaft portion 222 on the discharge space 12 side. The front end 221 is provided so as to protrude into the discharge space 12. A coil 24 is wound and provided on the discharge space 12 side of the shaft member 22, that is, on the tip portion 221 side of the shaft member 22. Further, when the outer diameter of the shaft portion 222 is A (mm) and the outer diameter of the tip portion 221 is B (mm), both 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80 are satisfied. It is desirable.

  If the outer diameter A of the shaft portion 222 is smaller than 1.5, the temperature of the shaft member 22 rises when the discharge lamp 1 is lit, and spatter is generated from the shaft member 22 and blackening occurs, which is not preferable. On the other hand, when A is larger than 3.0, the temperature of the shaft member 22 does not increase when the discharge lamp 1 is turned on, and the shaft member 22 is sputtered to improve electron radiation, and blackening occurs. It is not preferable. Therefore, it is desirable that the outer diameter A of the shaft portion 222 is 1.5 ≦ A ≦ 3.0.

  In addition, regarding a value B / A obtained by dividing the outer diameter B of the distal end portion 221 by the outer diameter A of the shaft portion 222, it is desirable that B / A ≦ 0.80. If B / A is larger than 0.80, the temperature at the tip is low, the discharge becomes unstable, and sputtering occurs, which is not preferable. Therefore, it is desirable that B / A ≦ 0.80.

  In this embodiment, the coil 24 is so-called single winding, but the coil 24 may be double winding. In short, the configuration of the coil may be any configuration. One end of the coil 24 may be welded to the shaft member 22.

Further, the shaft member 22 and the coil 24 may include an emitter (not shown) that is an electron-emitting material in order to improve electron-emitting properties. The emitter is provided by impregnating the shaft member 22 and the coil 24 in order to reduce the work function of the shaft member 22 and the coil 24. As the emitter, for example, thorium oxide (ThO ₂ ), hafnium carbide (HfC), or zirconium carbide (ZrC) is used. The emitter is contained in the shaft member 22 or the coil 24 by 0.50 to 2.0 wt% (weight%).

  As described above, in the shaft member 22 of the electrode 20, when the outer diameter of the shaft portion 222 is A (mm) and the outer diameter of the tip portion 221 is B (mm), 1.5 ≦ A ≦ 3.0 If both B / A ≦ 0.80 are satisfied, blackening of the arc tube can be suppressed.

  Here, in the shaft member 22 of the electrode 20 in the discharge lamp 1, examination was performed by changing A and B / A between the outer diameter A of the shaft portion 222 and the outer diameter B of the tip portion 221. The evaluation conditions are as follows.

Discharge lamp 1 (common): inner diameter = 20 mm, discharge space length = 375 mm, overall length of discharge lamp 1 = 500 mm, lamp voltage = 2500 V, lamp current = 8.9 A, lamp power = 22 kW, lighting time: 500 time.

  The outer diameter A of the shaft portion 222 is 1.3, 1.5, 2.0, 2.5, 3.0, 3.2 mm.

  The outer diameter B of the tip 221 / the outer diameter A of the shaft 222 = 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.90.

  Evaluation method: After 500 hours of lighting time, the discharge electrodes 20 of the discharge lamp 1 and the hermetic container 10 near the discharge vessel 1 are observed. If no blackening is visually observed, .DELTA. A visual evaluation of X was made when blackening was observed. Even when slight blackening was observed (in the case of “Δ” in FIG. 3), it was found that there was no problem in actual use. Further, when blackening was clearly observed (in the case of “X” in FIG. 3), the electrode was extremely worn out, and could not leak early or stably maintain the arc discharge. .

  The results are shown in FIG. As is clear from FIG. 3, when both 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80 are satisfied, blackening can be suppressed.

Note that the tip 221 may have a pointed end 223 as shown in FIG. The pointed end 223 is a pointed portion generated at the tip end portion 221 and is desirably provided at the tip end portion 221. In this case, for example, if there is a portion that clearly protrudes toward the discharge space 12 as compared with the flat portion 221, it may be the “tip 223”. Also, the tip 221 need not be completely flat. With such a configuration, instability of arc discharge that occurs when the discharge lamp 1 is turned on can be suppressed.
(Modification 1)

  FIG. 5 is a schematic view illustrating a first modification of the discharge lamp 1 shown in the first embodiment.

  As shown in FIG. 5, the shaft member 32 used in the discharge lamp 1 according to this modification includes a tip 221, a first shaft 224, and a second shaft 225. The first shaft portion 224 is larger than the second shaft portion.

  The shaft member 22 has a taper shape at the substantially center, and is formed integrally with the first shaft portion 224 and the second shaft portion 225. In the present modification, the outer diameter of the first shaft portion 224 corresponds to the “outer diameter A of the shaft portion 222” shown in the first embodiment.

Also in this modification, blackening can be suppressed by satisfying both 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80.
(Modification 2)

  FIG. 6 is a schematic view illustrating a second modification of the discharge lamp 1 shown in the first embodiment.

  As illustrated in FIG. 6, the shaft member 34 used in the discharge lamp 1 according to this modification is integrally formed in a tapered shape over the entire shaft member 34. In this modification, the portion having the largest outer diameter in the shaft portion 222, that is, the portion having the maximum outer diameter on the side where the coil 24 is provided corresponds to the “outer diameter A of the shaft portion 222”.

Also in this modification, blackening can be suppressed by satisfying both 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80.
(Modification 3)

  FIG. 7 is a schematic view illustrating a third modification of the discharge lamp 1 shown in the first embodiment.

  As shown in FIG. 7, the shaft member 36 used in the discharge lamp 1 according to the present modification has the tip portion 221 side of the shaft member 36 formed integrally with a curved surface.

  Also in this modification, blackening can be suppressed by satisfying both 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 ... discharge lamp,
10 ... an airtight container,
12 ... discharge space,
14 ... sealing part,
20 ... Electrode,
22 ... shaft material,
221 ... the tip,
222, 224, 226, 227 ... shaft,
24 ... Coil,
26 ... foil,
28 ... Outer lead 30 ... Base,
40 ... lead wire,
50: Terminal.

Claims (3)

An airtight container that transmits ultraviolet rays and has a discharge space and sealing portions formed at both ends of the discharge space;
Noble gas and mercury enclosed in the discharge space;
A pair of discharges having a shaft member provided with a part embedded in the sealing portion, a coil wound around the shaft portion, and a tip portion having an outer diameter smaller than that of the shaft portion provided in the discharge space An electrode;
Have
When the outer diameter of the shaft portion is A (mm) and the outer diameter of the tip portion is B (mm), the shaft member satisfies 1.5 ≦ A ≦ 3.0 and B / A ≦ 0.80. A discharge lamp that satisfies both.   The discharge lamp according to claim 1, wherein the tip has a tip. The discharge lamp according to claim 1 or 2, wherein the shaft member and the coil are impregnated with an emitter, and the emitter contains 0.50 to 2.0 wt% of any one of thorium oxide, hafnium carbide, and zirconium carbide. .

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