Foil sealed short arc mercury lamp

Abstract

The present invention provides a foil-sealed short-arc mercury lamp with a low crack incidence rate in the sealing portion. The foil-sealed short-arc mercury lamp (1) is a foil-sealed discharge lamp (rated power 13.5 kW), comprising a sealing body (3), an anode (4), a cathode (5), a lead rod (7), a cap (9) and a bead (6). Mercury and xenon gas are sealed in the sealing body (3), and a sealing portion (3a) is provided at both ends. A glass cap (9) is arranged on the sealing portion (3a). Five pieces of molybdenum metal foil (13) are arranged on the outer periphery of the cap (9). The length (Lb) of the bead (6) is 55 mm, and the cap length (Lc) is 40 mm (Lb>Lc). Bead length (Lb) / cap length (Lc) (hereinafter referred to as bead-to-cap ratio) = 1.38.

Description

Technical Field

[0001] The present invention relates to a foil-sealed short-arc mercury lamp, and more particularly to suppressing floating foil near a sealing portion. Background Art

[0002] Patent Document 1 discloses a foil-sealed mercury short-arc lamp in which mercury aggregation is less likely to occur during lighting.

[0003] In recent years, the above-mentioned foil-sealed mercury short-arc lamps have been required to have higher illuminance, and damage to the sealing portion has become a problem due to the increased load on the lamp.

[0004] The cause of the damage is briefly described. The sealing of the sealing part is performed by fusing the molybdenum foil and the glass, but the high load on the sealing part caused by the high load on the lamp causes the molybdenum foil at the fusing part to peel off from the glass (hereinafter referred to as floating foil). The glass around the gap created by the floating foil is subjected to thermal stress and internal pressure stress generated by mercury gas of several tens of atmospheric pressure when lit, so the sealing part is damaged.

[0005] In particular, on the cathode side, in addition to the load caused by such thermal stress and internal pressure stress, there are also chemical factors: cations such as mercury and metal impurities contained in glass parts are attracted to negative charges, which destroy the bond between the glass and the molybdenum foil in the sealing part.

[0006] Patent Document 2 discloses a technique in which a straight portion and a flat portion are formed on a substantially cylindrical glass member to reduce a non-welded region between the glass and the molybdenum foil and to improve the strength of the sealing portion.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2012-186121

[0010] Patent Document 2: Japanese Patent Application Publication No. 2020-24893 Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, if the glass component of Patent Document 2 is used, a corner portion is inevitably formed in the nearly cylindrical glass component due to the formation of a straight portion and a flat portion. Such a corner portion has the problem of generating cracks and gaps in the manufacturing process of forming the sealing portion. In addition, Patent Document 2 only improves the strength of the sealing portion, but does not reduce the load on the sealing portion itself.

[0013] An object of the present invention is to provide a foil-sealed short-arc mercury lamp which is less likely to produce floating foil.

[0014] Means for solving problems

[0015] (1) The foil-sealed short-arc mercury lamp of the present invention comprises: a glass sealing body having sealing parts at both ends; an electrode support rod having an electrode at the front end; a glass electrode support rod holding member, which is arranged at the sealing part and supports the end opposite to the front end of the electrode support rod; a glass electrode support rod intermediate support member, which is arranged adjacent to the electrode side of the electrode support rod holding member and supports the middle of the electrode support rod; two or more metal foils, which are arranged on the outer periphery of the electrode support rod holding member and are electrically connected to the electrode support rod; wherein the axial length of the electrode support rod intermediate support member is made longer than the length of the electrode support rod holding member. Therefore, it is possible to prevent the foil from floating, thereby providing a foil-sealed short-arc mercury lamp with a low cracking rate.

[0016] (2) In the foil-sealed short arc discharge lamp of the present invention, the axial length of the electrode support rod intermediate support member / the length of the electrode support rod holding member>1. Therefore, it is possible to prevent foil floating, thereby providing a foil-sealed short arc mercury lamp with a low crack incidence.

[0017] (3) In the foil-sealed short arc discharge lamp of the present invention, the rated power is 8 kW or more and the amount of mercury is 40 mg / mL or more. Therefore, in a so-called large lamp, a foil-sealed short arc mercury lamp can be provided which can prevent foil floating and has a low cracking rate.

[0018] The corresponding relationship between the terms used in the claims and the components in the embodiment will be described. The “electrode support rod holding member” corresponds to the cap 9 , and the “electrode support rod intermediate support member” corresponds to the bead 6 . BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : An explanatory diagram showing the sealing structure of the short arc discharge lamp 1 of the present invention.

[0020] Figure 2 : A diagram for explaining the temperature measurement method.

[0021] Figure 3 : A diagram showing the difference between the first embodiment and the second embodiment. DETAILED DESCRIPTION

[0022] 1. First Implementation

[0023] Figure 1 The main cross-sectional view of the short arc discharge lamp 1 of the present invention is shown. The short arc discharge lamp 1 is a foil sealed type discharge lamp (rated power 13.5 kW), and includes a sealing body 3 , an anode 4 , a cathode 5 , a lead rod 7 , a cap 9 , and a bead 6 .

[0024] Mercury and xenon gas are sealed in the sealing body 3, and the sealing parts 3a are provided at both ends. A glass cap 9 is arranged on the sealing part 3a. The base end of the lead rod 7 is inserted into the front end of the cap 9, and the cap 9 supports the lead rod 7. Five pieces of molybdenum metal foil 13 are provided on the outer periphery of the cap 9 as a conductive member for passing electricity to the cathode 5. A metal plate 15 having a through hole for inserting the lead rod 7 is provided at the front end of the cap 9.

[0025] In this embodiment, the amount of mercury is set to 40 mg / mL and the gas pressure is set to 700 Torr.

[0026] The lead bar 7 and the base 18 are electrically connected to the metal foil 13, an electric board (not shown), the rear lead bar 17, and the base 18, thereby allowing the cathode 5 provided at the front end of the lead bar 7 to be energized from the outside.

[0027] use Figure 1 B. The bead 6 is described. The bead 6 is made of glass, and one end of the bead 6 on the cap 9 side has substantially the same diameter as the metal plate 15 at the front end of the cap 9. In addition, a through hole 29 is provided in the center for inserting the lead rod 7.

[0028] In this embodiment, the length Lb of the bead 6 is set to 55 mm, and the cap length Lc is set to 40 mm (Lb>Lc). Bead length Lb / cap length Lc (hereinafter referred to as bead-cap ratio) = 1.38. By the way, conventionally, Lb is 35 mm, and the cap length Lc is 60 mm (bead-cap ratio is 0.6).

[0029] In addition, make 3 lamps of existing specifications and 2 Figure 1 The floating foil lengths of five lamps having the bead / cap ratio of the embodiment shown were measured.

[0030] Each lamp uses 5 pieces of metal foil on the cathode side, and there is a possibility of floating foil on the front and back sides. That is, the floating foil length (axial distance from the end of the metal washer 15 on the lamp holder side of the cathode side) and the occurrence of cracks were investigated at a total of 5 pieces × 5 pieces × 2 (front and back) = 50 places.

[0031] about Figure 1 The bead cap ratio lamps of the embodiment shown were both lit for 1000 hours, and none of them had floating foil.

[0032] In contrast, as shown in Table 1, three existing lamps were measured with a lighting time of 169 hours. One lamp had no cracks and 9 floating foils of less than 3 mm (Comparative Example 1). In addition, another lamp had cracks and 10 floating foils of less than 34 mm (Comparative Example 2). In addition, another lamp had no cracks and 10 floating foils of less than 22 mm (Comparative Example 3).

[0033] Table 1

[0034]

[0035] It should be noted that the lighting test was carried out under an over-input state (the input power was 14.2kW ​​relative to the rated power of 13.5kW, and the sealing part was covered with a tubular component with a wool fabric on the inner wall). Generally speaking, even if the rated power is 13.5kW, it is initially used from about 10kW, so the input power of 14.2kW ​​is an over-input state of more than 1.4 times.

[0036] The reason for the reduction of the above-mentioned floating foil is not clear, but the inventor believes that by reducing the temperature of the metal foil 13 when it is lit, that is, by making the beads longer and maintaining the distance between the metal foil and the light-emitting part as a heat source, the temperature of the welded part is reduced, thereby suppressing the metal cations that move to the sealing part from destroying the bond between the quartz glass and the molybdenum foil. It is believed that the floating foil of the sealing part and the accompanying breakage are caused by the following two influences: the strength reduction caused by the destruction of the bonding interface caused by the chemical reaction between the product (Mo-O-Si compound) of the bonding interface between the quartz glass and the molybdenum foil and the metal cations that move to the sealing part, and the strength reduction caused by the stress deformation caused by the thermal expansion difference between the metal foil and the glass. By lowering the temperature, the chemical reaction rate is reduced, and the stress deformation is also reduced. Therefore, the strength reduction caused by the two factors is alleviated and breakage can be prevented.

[0037] It should be noted that it is conventionally believed that if the axial length of the bead 6 is extended, unevaporated mercury accumulates in the gap between the through hole 29 and the lead bar 7, causing a problem of prolonged start-up time. However, even if the bead-cap ratio is set to 1 or more as in the present invention, there is no particular disadvantage.

[0038] The inventors measured the temperature of the metal foil 13. Figure 2 A temperature measurement method in this embodiment will be described.

[0039] In a lampshade 50 of a cube with a side of about 1m, a short arc discharge lamp 1 is vertically arranged with the anode 4 located at the top. In order to prevent the influence of light radiated from the cathode 5, a light shielding box 51 is provided in the lampshade 50 near the sealing portion covering the cathode 5 side. Black body paint is applied to the inner surface of the light shielding box 51. A radiation thermometer (A6261 manufactured by FLIR Corporation) (not shown) is arranged perpendicular to the metal foil 13 through the measuring window 53 of the lampshade 50. It should be noted that the emissivity is set to 0.37.

[0040] The short arc discharge lamp 1 was lit at a voltage of 108 V and a DC current of 92.6 A. After it reached a stable state, the temperature was measured 4 milliseconds after the lamp was turned off using a radiation thermometer. This was to prevent the arc light when the lamp was lit from affecting the measured value.

[0041] It should be noted that the voltage of 108V and the DC current of 92.6A were set to light up in the temperature measurement in order to set the input power to be the same as that when used under a certain condition of general illumination. That is, even if the rated power is 13.5kW, it is used from about 10kW in the early stage, and the power is increased when the illumination decreases with use.

[0042] The temperature of the metal foil 13 of the short arc discharge lamp 1 is reduced by about 40 degrees on average compared to conventional products.

[0043] In order to confirm the correlation between foil floating and cracks in the sealing part, the inventor investigated the length of foil floating and the crack occurrence rate of 51 used lamps collected from customers ("5 foils / lamp", so the total number of the front and back sides of each lamp is 510). The results are shown in Table 2. Among the 51 lamps, 4 lamps had cracks. In addition, among these 4 lamps, 1 lamp had cracks starting from the 2nd foil.

[0044] Table 2

[0045] crack Time of use Table 1 Table 2 Table 3 Table 4 Table 5 Back 1 Back 2 Back 3 Back 4 Back 5 1 have 140 3 8 8 30 30 25 33 33 33 33 2 none 536 4 4 4 4 4 3 2 3 3 3 … … … … … … … … … … … … … 31 none 1344 3 3 3 3 3 0 0 0 0 0 32 have 873 2 4 5 2 0 3 22 5 21 3 33 none 1344 4 4 4 4 5 0 0 0 0 0 34 none 1018 7 7 5 5 5 11 20 22 8 6 35 have 405 2 2 3 3 2 0 0 0 30 0 36 none 461 1 2 2 2 2 0 3 2 2 2 … … … … … … … … … … … … … 50 none 666 8 8 8 8 8 6 7 5 5 6 51 have 1000 4 4 4 4 4 4 19 16 4 5

[0046] The statistical results for 510 in Table 2 are shown in Table 3. Thus, among the existing products, 109 / 510=21.4% had no floating foil, and the rest had floating foil. In addition, regarding the occurrence of cracks among them, for foils with a floating foil length of more than 26 mm, 63% had cracks; for foils with a floating foil length of 21 to 25 mm, 17% had cracks; for foils with a floating foil length of 16 to 20 mm, 14% had cracks; and for foils with a floating foil length of 1 to 5 mm, 1% had cracks.

[0047] Table 3

[0048]

[0049] Thus, the longer the floating foil length is, the higher the crack occurrence rate is. In contrast, even in conventional lamps, the crack occurrence rate of lamps without floating foil is 0.

[0050] The crack ratio means that there are 10 locations with cracks in total, and this is used as the denominator to indicate in which data interval the cracks are distributed. In this case, 50% are foils with a floating foil length of 26 mm or more.

[0051] 2. Second Implementation

[0052] In the first embodiment, the taper length of the front end of the cap 9 is 21 mm, but a short arc discharge lamp having a taper length of 4 mm was produced. The taper angle of the cap 9 is calculated to be 10 to 46 degrees. Figure 3 A and B show sealing part component diagrams of the first embodiment and the second embodiment. Five short arc discharge lamps were manufactured using these sealing part component diagrams.

[0053] In this embodiment, even when the device is lit for 120 hours in the above-mentioned over-input test (the input power is 14.2 kW relative to the rated power of 13.5 kW, and the sealing part is covered with a tubular component with a wool fabric on the inner wall), there is “no” floating foil and of course “no” cracks.

[0054] By increasing the taper angle of the cap 9 in this manner, the possibility of foil floating is reduced as described below.

[0055] Usually, the cross section of the foil in the width direction becomes thinner as it moves toward the end (blade). This is to improve the adhesion of the end. However, in the tapered portion of the bead, the side of the metal foil is cut off to avoid overlapping of the five metal foils. As a result, the blade portion also disappears. The portion without the blade is prone to floating foil. If the length of the tapered portion can be shortened, the length of the portion without the blade becomes shorter, so the possibility of floating foil is reduced.

[0056] 3. Other Implementation Methods

[0057] In this embodiment, a short arc mercury lamp with a rated power of 13.5 kW is described, but the rated power is not limited to this.

[0058] It should be noted that, generally speaking, the greater the rated power, the higher the internal pressure; the higher the internal pressure, the more likely it is that the above-mentioned floating foil will occur. However, even if the rated power is high, there are cases where cracks will not occur in that way. This is because, even if the rated power is high, there are lamps with not so high internal pressure. The inventors have investigated existing lamps and found that when the rated power is above 8kW and the amount of mercury per unit volume exceeds 40mg / mL, floating foil occurs to the extent that cracks occur. Therefore, the present invention is useful for foil-sealed short-arc mercury lamps with a rated power of more than 8kW and a mercury amount of more than 40mg / mL.

[0059] In the present embodiment, the case where the bead cap ratio is 1.38 is described, but the present invention is not limited thereto, and the bead cap ratio may be 1 or more.

[0060] In this embodiment, the bead cap ratio is increased compared with the conventional method to prevent floating foil. Therefore, the length of the bead can be extended without changing the distance from the reference surface to the cathode.

[0061] Explanation of symbols

[0062] 1....Short arc discharge lamp

[0063] 3. Sealing body

[0064] 3a...Seal

[0065] 4....Anode

[0066] 5....Cathode

[0067] 6....Pearl

[0068] 7...Lead rod

[0069] 9....Hat

[0070] 13...metal foil

[0071] 15...Metal plate

[0072] 51...Light-shielding box

Claims

1. A foil-sealed short-arc mercury lamp comprising: A glass seal having sealing portions at both ends; an electrode support rod having an electrode at a front end; a glass electrode support rod holding member disposed at the sealing portion and supporting an end portion of the electrode support rod opposite to a front end thereof; A glass electrode support rod intermediate support component, which is arranged adjacent to the electrode side of the electrode support rod holding component and supports the middle of the electrode support rod; Two or more metal foils are arranged on the periphery of the electrode support rod holding component and are electrically connected to the electrode support rod; It is characterized in that On the cathode side, the axial length of the electrode support rod intermediate support member is made longer than the length of the electrode support rod holding member.

2. The foil-sealed short arc mercury lamp according to claim 1, characterized in that: The rated power is 8 kW or more and the amount of mercury is 40 mg / mL or more.

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