JP7591621B2 - Discharge lamp and method for manufacturing the same - Google Patents

Description

The present invention relates to discharge lamps such as short arc type discharge lamps, and in particular to the sealing structure of discharge lamps.

In short arc discharge lamps, glass sealing tubes are integrally formed on both ends of the light emitting tube with the electrodes sealed, and mounting parts are enclosed within the sealing tubes. In the mounting parts, an electrode support rod is inserted into a cylindrical glass tube and is held by the glass tube. Metal foil is placed along the surface of a columnar glass member (glass rod), and power is supplied to the electrode side through the metal foil. In high-power discharge lamps, an annular member such as a metal ring is fixed to the electrode support rod, and multiple metal foils are welded to the outer circumferential surface of the annular member (see Patent Document 1).

JP 2009-238671 A

Metal foil is hard and does not bend easily in the width direction. Therefore, when the metal foil is welded to the annular component, the edges of the foil along the axial direction do not fit the outer surface of the glass component and float above the surface. If the mounting components are sealed in this state, that is, if the glass sealing tube and the glass component are welded together, wrinkles and kinks will form in the metal foil. These wrinkles and kinks may cause cracks in the sealing area.

Therefore, in short arc type discharge lamps and the like, it is necessary to seal the mounting parts in a way that prevents wrinkles from forming in the metal foil.

The manufacturing method of a discharge lamp according to one aspect of the present invention involves preparing a plurality of metal foils for the mounting part, which are metal foils that have a floating height of 1.2 mm or less when contacted with the columnar glass member of the mounting part along the axial direction of the glass member and are welded to a conductive ring-shaped member that connects to an electrode support rod, pressing the plurality of metal foils with metal, and fusing the mounting part, which includes the columnar glass member and the plurality of metal foils pressed with metal, into a sealing tube formed integrally with the light-emitting tube.

Another aspect of the present invention is a method for manufacturing a discharge lamp, which involves preparing a plurality of metal foils for the mounting part, the metal foils being welded to a conductive annular member that connects to an electrode support rod, and which have a floating height of 0.8 mm or less when in contact with the columnar glass member of the mounting part along the axial direction of the glass member, and fusing the mounting part, which includes the columnar glass member and the plurality of metal foils to which a force is applied toward the center of the glass member along the circumferential direction of the glass member so as to contact the glass member across the entire width, into a sealing tube formed integrally with the light emitting tube.

Another aspect of the present invention is a discharge lamp comprising: a columnar glass member of a mounting part that is enclosed in a sealing tube that is formed integrally with the light-emitting tube, the columnar glass member being fused to the sealing tube; and a plurality of metal foils of the mounting part that extend in the lamp axial direction between the sealing tube and the glass member and apply a force toward the center of the glass member along the circumferential direction of the glass member so as to contact the glass member over the entire width, the discharge lamp being characterized in that the width of the metal foil along the circumferential direction is determined to satisfy the following formula.

L/2×sin(90L/πD)≦0.8

Here, D (mm) represents the diameter of the glass member, and L (mm) represents the width of the metal foil.

Another aspect of the present invention, a discharge lamp, is a mounting part that includes a columnar glass member, a plurality of metal foils extending along the surface of the glass member, and a conductive annular member that contacts the plurality of metal foils at the outer circumferential surface and connects to an electrode support rod, and the mounting part in which the plurality of metal foils are pressed by metal onto the outer circumferential surface of the annular member is enclosed in a sealing tube that is formed integrally with the light emitting tube.

The metal that presses the metal foil onto the outer peripheral surface of the annular member can be configured, for example, to clamp, tie, or wrap the metal foil tightly so that the metal foil is pressed around the entire circumference.

Another aspect of the present invention, a discharge lamp, is a mounting component that includes a columnar glass member, a plurality of metal foils extending along the surface of the glass member, and a conductive annular member that contacts the plurality of metal foils at the outer circumferential surface and connects to an electrode support rod, and the mounting component in which the plurality of metal foils are biased by metal on the outer circumferential surface of the annular member is enclosed in a sealing tube that is integrally formed with the light emitting tube.

Another aspect of the present invention, a discharge lamp, is a mounting component that includes a columnar glass member, a plurality of metal foils extending along the surface of the glass member, and a conductive annular member that contacts the plurality of metal foils at the outer circumferential surface and connects to an electrode support rod, and the mounting component in which the plurality of metal foils are pressed by metal onto the outer circumferential surface of the annular member and onto the outer surface of the glass member is enclosed in a sealing tube that is formed integrally with the light emitting tube.

For example, the axial length of the area of the multiple metal foils pressed onto the outer surface of the glass member is in the range of 0.5 to 2.0 times the axial length of the annular member.

According to the present invention, in short arc type discharge lamps and the like, it is possible to seal the mounting parts without causing wrinkles in the metal foil.

1 is a schematic cross-sectional view of a short arc type discharge lamp according to an embodiment of the present invention. FIG. 4 is a plan view of a mounting part showing the arrangement of metal foils and pressure-contact members. FIG. 2 is a diagram showing a sheet of metal foil before welding of the pressure welding member. FIG. 2 is a cross-sectional view showing a part of the vicinity of an end of the metal foil in FIG. 1 . 1 is a diagram showing the relationship between the width of a metal foil, the floating height, and the diameter of a glass member. FIG. 2 is a cross-sectional view taken along the inner metal ring before welding the insulation displacement member to the metal foil.

Below, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 is a schematic cross-sectional view of a short arc type discharge lamp according to this embodiment.

The short arc type discharge lamp 10 is a discharge lamp in which an anode 14 and a cathode 16 are arranged opposite each other inside an arc tube 12 made of quartz glass, and quartz glass sealing tubes 20, 60 are integrally formed at both ends of the arc tube 12 so as to face each other. Both ends of the sealing tubes 20, 60 are sealed with bases 80A, 80B.

Parts (hereafter referred to as mounting parts) 18A and 18B that support the anode 14 and cathode 16 and seal the discharge space 11 in the light-emitting tube 12 are enclosed inside the sealing tubes 20 and 60, respectively. The mounting part 18A comprises a cylindrical thick-walled glass tube (hereafter referred to as glass tube) 24, a columnar glass member 34, and multiple metal foils 36. The mounting part 18B has a similar configuration. Mercury and a rare gas are enclosed in the discharge space 11.

Inside the sealed tube 20, a conductive electrode support rod 22 that supports the anode 14 is arranged along the electrode axis E (sealed tube axis). The electrode support rod 22 is inserted into an axial hole 24A formed in the glass tube 24 and is held by the glass tube 24.

On the other hand, at the end of the sealed tube, a conductive lead rod 28 is arranged to face the electrode support rod 22. The electrode support rod 22 and the lead rod 28 are axially inserted into holes (recessed portions) 34A and 34B provided at both ends of the glass member 34, and the glass member 34 holds the electrode support rod 22 and the lead rod 28. The lead rod 28 is connected to an external lead wire (not shown) that is connected to a power supply unit (not shown).

Metal rings (annular members) 26, 32 are arranged on both ends of the glass member 34, and the electrode support rod 22 and lead rod 28 are welded to axial holes 26A, 32A of the metal rings 26, 32. The metal ring (hereinafter referred to as the inner metal ring) 26 closest to the light emitting tube 12 is sandwiched between disk-shaped circular foils 42, 44, and the other metal ring (hereinafter referred to as the outer metal ring) 32 is similarly sandwiched between disk-shaped circular foils (not shown here).

Between the inner metal ring 26 and the outer metal ring 32, multiple strip-shaped metal foils (e.g., molybdenum foils) 36 extend along the outer surface of the glass member 34 in the direction of the lamp axis E, and both ends are welded to the outer peripheral surfaces 26S, 32S of the inner metal ring 26 and the outer metal ring 32. The outer metal ring 32 electrically connects the lead rod 28 and the metal foil 36, and the inner metal ring 26 electrically connects the metal foil 36 and the electrode support rod 22. This allows power to be supplied to the anode 14 from the lead rod 28, which is connected to the power source.

A metal annular pressing member 50 is provided on the outer peripheral surface 26S of the inner metal ring 26. The annular pressing member 50 presses the metal foil 36 toward the glass member 34 so that the metal foil 36 is aligned with the outer surface of the glass member 34, and fastens the end of the metal foil 36 to the glass member 34 (inner metal ring 26). In other words, the pressing member 50 is not a member that covers the periphery of the glass member 34 and the inner metal ring 26, but is configured as a member that urges the metal foil 36 toward the outer surface of the glass member 34.

Figure 2 is a plan view of the mounting part 18A showing the arrangement of the metal foil 36 and the pressure contact member 50. Here, the mounting part 18A is shown as seen from the axial direction before sealing the sealing tube 20. However, the thickness of the metal foil 36 and the pressure contact member 50 is exaggerated. In addition, both axial edges 36K1, 36K2 of the metal foil 36 are actually tapered like a knife edge.

The metal foil 36 is made up of six metal foils of the same width, which are arranged at a predetermined interval from each other along the circumferential direction of the glass member 34. Here, the six metal foils 36 are arranged symmetrically with respect to the axis E, so the metal foils 36 are arranged at equal intervals in the circumferential direction.

The pressure-contact member 50 is a ring-shaped metal member having a circumferential length approximately equal to one circumference of the glass member 34 (inner metal ring 26) and having an overlapping portion 50T. Here, the pressure-contact member 50 is made of metal foil. The pressure-contact member 50 is welded to the metal foil 36 on the outer peripheral surface 26S of the inner metal ring 26.

Figure 3 shows a sheet of metal foil 36 before welding the pressure-welding member 50. The metal foil 36 is a flat band-shaped metal that is hard and does not bend easily in the width direction. When such a metal foil 36 is placed on the outer surface of the glass member 34, the further away from the contact area the greater the gap ΔT between the glass member 34 and the metal foil 36 (hereinafter referred to as the floating height). In addition, the longer the width L of the metal foil 36, the greater the floating height ΔT.

The pressure contact member 50 bends the metal foil 36 along the circumferential direction of the glass member 34 at and near the outer peripheral surface 26S of the inner metal ring 26, applying a force so that the metal foil 36 comes into contact with the glass member 34 over its entire width L.

Figure 4 is a cross-sectional view showing a portion of the metal foil 36 near the end of Figure 1.

The pressing member 50 has an axial width T, and its two circumferential edges 50E1, 50E2 are located on the surfaces of the glass member 34 and the glass tube 24, respectively. That is, the pressing member 50 extends in the lamp axial direction across the glass member 34, the inner metal ring 26, and the glass tube 24. Note that in FIG. 4, the thicknesses of the pressing member 50, the circular foils 42, 44, and the metal foil 36 are exaggerated, and the outer diameters of the glass member 34, the inner metal ring 26, and the glass tube 24 may be approximately the same.

The axial length J of the area where the metal foil 36 is pressed against the pressure contact member 50 on the outer surface of the glass member 34 (hereinafter referred to as the pressure contact length) is set to a range of 0.5 to 2.0 times the thickness (axial length) RT of the inner metal ring 26. If it is less than 0.5 times, the metal foil 36 cannot be sufficiently pressed against the surface of the glass member 34, while if it exceeds 2.0 times, the welding area between the glass member 34 and the sealing tube 20 decreases, affecting the reliability of the sealing structure.

The back surface of the pressure contact member 50 has an uneven portion formed at the contact point with the end 36T of the metal foil 36, particularly near both edges 36K1 and 36K2. Here, the unevenness is formed on the back surface (and front surface) of the pressure contact member 50 by embossing. However, unevenness may also be formed on other parts of the back surface (and front surface), and the unevenness is not limited to embossing.

The width L of the metal foil 36 cannot be made extremely short because it depends on the power (current value). However, it is required that the width L be set so as to suppress the floating height ΔT of the metal foil 36. The width L of the metal foil 36 can be determined based on the relationship between the allowable range of this floating height ΔT and the diameter D of the glass member 34.

FIG. 5 is a diagram showing the relationship between the width L of the metal foil, the floating height ΔT, and the diameter D of the glass member 34. Assuming that θ″ ≈ θ/2 and sin(θ/2) ≈ ΔT ÷ (L/2), the floating height ΔT can be expressed by the following equation. However, reference symbol 36′ in FIG. 5 represents the position of a virtual metal foil 36.

ΔT=L/2×sin(90L/πD) (1)

It is empirically derived that this floating height ΔT is 1.2 or less. Therefore, the width L of the metal foil 36 relative to the diameter D of the glass member 34 is determined so as to satisfy the following formula, where the diameter D of the glass member 34 satisfies the range of 15≦D≦35 mm.

L/2×sin(90L/πD)≦1.2 (2)

Figure 6 is a cross-sectional view along the inner metal ring 26 before the pressure contact member 50 is welded to the metal foil 36. A method for manufacturing a discharge lamp will be described using Figure 6. Note that the gap between the pressure contact member 50 and the metal foil 36 is exaggerated in Figure 6.

Multiple metal foils 36 are arranged axially along the surface of the columnar glass member 34, and the ends 36T of the metal foils are welded to the outer peripheral surface 26S of the inner metal ring 26 into which the electrode support rod 22 is axially inserted. Then, a process is performed in which the pressure contact member 50 is welded to the metal foils 36 along the outer peripheral surface 26S of the inner metal ring 26.

When welding the pressure contact members 50 to the metal foils 36, at least one spot weld is applied to each metal foil 36 (see arrows). Meanwhile, one or two or more spot welds are applied to both ends of the metal foil 36 facing the overlapping portion 50T of the pressure contact member 50. By welding in this manner, the metal foil 36 is fastened by the pressure contact member 50. Direct welding may be performed between the pressure contact member 50 and the inner metal ring 26, but this is not necessary for manufacturing efficiency.

After welding the pressure-contact member 50 and the metal foil 36 together, the process moves on to the sealing process. During the sealing process, the sealing tube 20 is heated by a gas burner or the like to reduce its diameter, and is fused to the glass tube 24 and glass member 34. Through these steps, a discharge lamp is manufactured.

Thus, according to this embodiment, in a discharge lamp 10 in which a plurality of metal foils 36 are arranged on the outer surface of a columnar glass member 34 along the lamp axis direction and the metal foils 36 are welded to the outer peripheral surface 26S of an inner metal ring 26 that connects to an electrode support rod 22, an annular pressing member 50 presses and tightens the metal foils 36 on and near the outer peripheral surface 26S of the inner metal ring 26 toward the center of the inner metal ring (glass member).

The installation of such a pressure-contact member 50 can prevent the metal foil 36 from floating from the outer surface of the glass member 34. As a result, it is possible to prevent wrinkles and kinks from occurring at least in the end 36T of the metal foil 36 during sealing. In particular, both axial edges 36K1, 36K2 (see FIG. 2) of the metal foil 36 are actually tapered into a knife-edge shape. Therefore, by preventing floating with the pressure-contact member 50, the knife-edge-shaped portion can be sealed along the surface of the glass member 34.

In addition, both edges 36K1, 36K2 of the metal foil 36 come into contact with the uneven portions formed on the pressure contact member 50. This allows both edges 36K1, 36K2 of the metal foil 36 to be pressed firmly together, reliably preventing the metal foil 36 from floating. Furthermore, the above formula (2) prevents the width L of the metal foil 36 from becoming longer than necessary relative to the diameter of the glass member 34, and the floating height can be reduced.

The number of metal foils 36 is not limited to six, and may be more or less than six. In this case, the thickness and number of metal foils 36 may be adjusted taking into consideration the heat capacity of the metal foils 36 and the welding area during sealing. In addition, the pressing member 50 has a circumferential length of approximately one circumference of the glass member 34 (inner metal ring 26), but it may be two or three circumferences, or it may be pressed multiple times.

To demonstrate the effectiveness of the discharge lamp of this embodiment, short arc type discharge lamps (Examples 1 and 2) with different diameters of the glass member and widths of the metal foil were manufactured, along with a conventional short arc type discharge lamp (Comparative Example), and a comparative experiment was conducted on the occurrence of wrinkles and twists in the metal foil (at its ends). A visual inspection experiment was conducted to confirm the occurrence of wrinkles and twists. Table 1 shows the results of Comparative Example 1, Example 1, and Example 2.

As shown in Table 1, wrinkles and kinks occurred at the edges of the metal foil in the comparative example, but did not occur in Examples 1 and 2.

10 Discharge lamp 20 Sealed tube 26 Inner metal ring (annular member)
34 Glass member 36 Metal foil 50 Press-contact member

Claims (3)

a metal foil that has a floating height of 1.2 mm or less when brought into contact with a columnar glass member of a mounting component along an axial direction of the columnar glass member, the metal foil being welded to a conductive annular member connected to an electrode support rod;
the plurality of metal foils are pressed against the columnar glass member by metal so as to contact the annular member and the columnar glass member at and near the outer peripheral surface of the annular member along the entire width of the columnar glass member in the circumferential direction, and so that the axial length of the region pressed on the outer surface of the columnar glass member is in the range of 0.5 to 2.0 times the axial length of the annular member ;
a mounting part including the columnar glass member and the plurality of metal foils pressed by the metal, said mounting part being fused into a sealing tube formed integrally with said light-emitting tube, thereby sealing said mounting part within said sealing tube. a metal foil having a floating height of 0.8 mm or less when brought into contact with a columnar glass member of a mounting component along an axial direction of the columnar glass member, the metal foil having knife-edge ends and welded to a conductive annular member connected to an electrode support rod is prepared;
a mounting component including the columnar glass member and the plurality of metal foils, the plurality of metal foils being pressed toward the center of the columnar glass member on the outer peripheral surface of the annular member and in its vicinity so as to contact the annular member and the columnar glass member over the entire width along the circumferential direction of the columnar glass member, is fused into a sealing tube formed integrally with the light-emitting tube, thereby sealing the mounting component in the sealing tube. a columnar glass member of a mount component to be sealed in a sealing tube formed integrally with the light emitting tube, the columnar glass member being fused to the sealing tube;
a plurality of metal foils of the mounting component extending in the lamp axial direction between the sealing tube and the columnar glass member, the metal foils applying a force toward the center of the columnar glass member on the outer peripheral surface of a conductive annular member connected to an electrode support rod and in the vicinity thereof so as to contact the annular member and the columnar glass member along the circumferential direction of the columnar glass member over the entire width of the columnar glass member;
the mounting component including the plurality of metal foils is brought into contact with the annular member and the glass member at and near the outer peripheral surface of the annular member along the circumferential direction of the columnar glass member over the entire width thereof by a force applied to the plurality of metal foils, the mounting component being fused to the sealing tube and sealed within the sealing tube;
A discharge lamp characterized in that the width of the metal foil along the circumferential direction is determined to satisfy the following formula.

L/2×sin(90L/πD)≦0.8


Here, D (mm) represents the diameter of the columnar glass member, and L (mm) represents the width of the metal foil.

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