JP2005251449A - Low-pressure mercury vapor discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-pressure mercury vapor discharge lamp capable of suppressing temperature variation of the coldest point part, of preventing dispersion of lamp characteristics between lamps from occurring, and of improving the lamp characteristics. <P>SOLUTION: This low-pressure mercury vapor discharge lamp comprises: a double spiral arc tube 2; a holder 3 for holding both ends of the arc tube 2; a lighting circuit 4 formed and incorporated on the side opposite to the arc tube of the holder 3; a case 6 mounted to the holder 3 so as to cover the lighting circuit 4 while having a bulb base 5; and an outer tube 7 mounted by covering the arc tube 2. A projection part 9 being a coldest point presumption part of the arc tube 2 is embedded in a thermally conductive medium 10 and thermally connected thereto. For the thermally conductive medium 10, a substance prepared by mixing a silicone resin with aluminum powder is used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a low-pressure mercury vapor discharge lamp provided with a curved arc tube in an outer tube.

  As a low-pressure mercury vapor discharge lamp provided with a curved arc tube in the outer tube, for example, a light bulb-type fluorescent lamp instead of a general light bulb is known.

  As a conventional bulb-type fluorescent lamp, as shown in FIG. 4, there is a lamp with an outer tube in which a curved arc tube 2 is provided in an outer tube 7. In the case with the outer tube, the arc tube 2 standingly held on the holder 3 is covered with an outer tube 7 made of glass of a glass shape, and the lighting circuit 4 (see FIG. A case 6 provided with the same E-shaped base 5 as a general light bulb is mounted on the holder 3 so as to cover the lighting circuit 4.

  As the arc tube 2, a double helix arc tube 2 is used, and this double helix arc tube 2 is a straight tubular glass tube bent into a double helix. A pair of tungsten coil electrodes filled with an electron emitting material are hermetically sealed at both ends of the tube, and a phosphor is applied to the inner surface of the tube. Also, mercury Hg and argon as a buffer gas are contained in the tube. Noble gas is enclosed.

  By the way, it is well known that in a bulb-type fluorescent lamp with an outer tube, mercury enclosed in the arc tube is not a simple substance but is enclosed in the form of an amalgam such as Bi-In-Hg. This is because the mercury vapor pressure in the arc tube, which has a relatively high temperature, is reduced / adjusted so that the lamp efficiency is within the optimum range with the highest efficiency, because the outer tube is provided during steady lamp operation. is there.

In addition, in order to suppress an increase in mercury vapor pressure in the type with the outer tube, the mercury in the arc tube 2 is basically sealed in a single form even with the outer tube, and the coldest spot 9 of the arc tube 2 Means have been proposed for connecting the outer tube 7 with a heat conductive medium 15 to thereby reduce the temperature at the coldest spot (for example, Patent Document 1 and Patent Document 2).
JP 58-177891 A JP 2003-263972 A

  In a low-pressure mercury vapor discharge lamp equipped with an arc tube 2 made of a curved glass tube such as a double helix, mercury is enclosed and present in the arc tube 2 in a single or near form, and the inner diameter of the arc tube is 5 to 5. 9 mm, and the coldest spot planned spot 9 which is the coldest spot during light emission of the arc tube 2 and the outer tube 7 are joined by a heat conductive medium 15 made of silicone resin, so that the luminous flux rise at the time of starting the lamp is established. The upper characteristic is improved to a level equivalent to that of a general fluorescent lamp, and the temperature at the coldest spot of the arc tube 2 can be set to an optimum range of 60 to 65 ° C. at which the maximum lamp efficiency can be obtained. It has been found that high levels above / W are achieved.

  However, according to this configuration, it has been found that the range of variation in lamp efficiency between lamps completed in mass production is relatively large. For example, in a mass production lot of a 12W product type instead of a general light bulb 60W using a double spiral arc tube, a variation range of lamp efficiency of 58 to 68 lm / W was confirmed.

  When this factor was analyzed, it was found that the temperature at the coldest spot fluctuated relatively greatly among the completed lamps due to variations in the filling amount and filling shape of the silicone resin, which is a heat conductive medium. It has also been found that if the fluctuation of the coldest spot temperature can be suppressed, the variation range of lamp efficiency can be narrowed and the average value can be increased.

  The present invention has been made to solve such problems, and suppresses temperature fluctuations at the coldest spot, does not cause variations in lamp characteristics between lamps, and improves lamp characteristics. The object is to obtain a low-pressure mercury vapor discharge lamp that can be produced.

  The low-pressure mercury vapor discharge lamp according to claim 1 is provided with an arc tube having a pair of electrodes at both ends and a curved discharge path inside the outer tube, and the arc tube is the outermost during light emission. While having the coldest spot planned location which becomes the cold spot location, the coldest spot planned location and the portion of the outer pipe facing the coldest spot planned location through a resin thermal conductive medium The heat conductive medium is connected and metal powder is mixed.

  As a result, the thermal conductivity of the heat conductive medium can be increased, and the cooling effect of the coldest spot of the arc tube between the lamps can be increased. Therefore, even if the coupling distance varies between the mass production lamps, the cold spot temperature of the arc tube Fluctuations can be suppressed. Furthermore, the variation width of the lamp efficiency can be reduced, and the average value can be increased.

  According to a second aspect of the present invention, in the configuration of the first aspect, the coldest spot planned portion is in direct contact with the outer tube.

  Invention of Claim 3 has the structure which the part of the outer tube | pipe which the coldest-spot planned location and this coldest-spot planned location contact directly fit, and it contacted directly in the structure of Claim 1. .

  Invention of Claim 4 has the structure by which the location where the said coldest spot planned location and the said outer tube | pipe are directly contacting in the structure of Claims 2-3 is welded.

  According to the first aspect of the present invention, the thermal conductivity of the heat conductive medium can be increased, and the cooling effect of the coldest spot of the arc tube between the lamps can be increased. Therefore, even if the coupling distance varies between the mass production lamps. Variations in the coldest spot temperature of the arc tube can be suppressed. Furthermore, the variation width of the lamp efficiency can be reduced, and the average value can be increased.

  According to the second aspect of the present invention, the heat at the coldest spot can be transferred to the outer tube, and the cold spot temperature fluctuation of the arc tube is coupled with the action of the heat conductive medium mixed with the metal powder. Can be further suppressed.

  Further, according to the invention described in claim 3, the heat of the coldest spot can be transmitted to the outer tube as much as the contact area increases, and combined with the action of the heat conductive medium mixed with the metal powder, The fluctuation of the coldest spot temperature can be further suppressed. Further, the welding operation between the coldest spot and the outer tube can be easily performed.

  According to the fourth aspect of the present invention, the strength of the place where the coldest spot and the outer tube are in direct contact can be improved, and the strength against vibration and impact during lamp transportation can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A light bulb-type fluorescent lamp 1 (hereinafter referred to as the present invention A) as a first embodiment of the present invention shown in FIG. 1, which is a substitute for a general light bulb 60W, is a double spiral arc tube 2 and the arc tube 2 And a series inverter type lighting circuit 4 (indicated by a broken line in the figure) provided on the side opposite to the luminous bulb of the holder 3 and a light bulb base 5, and a lighting circuit 4, a funnel-shaped case 6 attached to the holder 3 so as to cover 4, an arc tube 2 that covers the arc tube 2, and an opening is formed by the inner peripheral surface of the large-diameter side opening of the case 6 and the outer peripheral surface of the holder 3. And a glass outer tube 7 having a shape formed by being fixed to the gap with an adhesive.

  The arc tube 2 is a curved glass tube formed by processing a straight tube glass into a so-called spiral shape, and electrodes (not shown) are sealed at both ends. A fluorescent material is applied to the inner surface of the arc tube 2, and in addition to about 5 mg of mercury, 550 Pa of argon as a buffer gas is sealed in the tube. A three-wavelength region phosphor was used as the phosphor. Further, the mercury sealed in the arc tube 2 is basically present in such a form that the mercury vapor pressure during operation of the arc tube 2 exhibits a vapor pressure value of mercury alone. Therefore, in the manufacturing process of the arc tube 2, the mercury may be single or may be sealed in the form of, for example, zinc mercury or tin mercury in which the mercury vapor pressure during the operation exhibits a value close to that of the single mercury.

  The inner diameter of the arc tube 2 is 8.2 mm, the distance between the electrodes is 400 mm, the arc tube 2 has a double spiral shape of about 4.5 turns, and mercury is enclosed in the tube in the form of single or close to the single as described above. ing. Further, a projection 9 is formed at the tip 8 on the side opposite to the holder 3 of the arc tube 2 as a coldest spot planned spot which becomes the coldest spot during light emission (during the travel), and this allows mercury The vapor pressure during operation is uniquely determined by the temperature at the coldest spot.

  The outer tube 7 has an outer diameter of 55 mm and a thickness of about 1.3 mm. The inner surface of the outer tube 7 is coated with a diffusion film (not shown) having a total diffusion transmittance of about 97% mainly composed of calcium carbonate.

  The projection 9, which is the coldest spot of the arc tube 2, has a height of about 3 mm and a thickness of about 0.06 mm. The projection 9 of the arc tube 2 and the outer tube 7 facing the projection 9 The protrusion 9 is embedded in the heat conductive medium 10 while being separated from the portion by about 1.7 mm. The thermally conductive medium 10 is filled and in contact with the portion of the outer tube 7 facing the protruding portion 9 of the arc tube 2, and therefore, the protruding portion 9 and the outer tube 7 of the arc tube 2 serve as a thermally conductive medium. It is the composition connected thermally via.

  The heat conductive medium 10 is a mixture of silicone resin and metal powder such as aluminum powder.

  As the heat conductive medium 10 in which aluminum powder is mixed as a metal powder, a mixture obtained by mixing and stirring an aluminum powder having an average particle diameter of 10 to 50 μm in a silicone resin is used.

  Next, the product A of the present invention was compared with a comparative product described later shown in FIG.

  The comparative product 14 shown in FIG. 4 has a light-transmitting silicone resin 15 as a heat conductive medium interposed between the outer tube 7 and the projection 9 which is the coldest spot of the arc tube 2. The protruding portion 9 and the outer tube 7 are thermally connected via a silicone resin 15. Further, a gap of about 1.7 mm is opened between the protruding portion of the arc tube 2 and the outer tube 7, and this gap is filled with a silicone resin 15. Fifty comparative products 14 having such a configuration were produced, and their lamp characteristics were measured. As a result, the average value of the lamp efficiency was 63 lm / W, and the variation range was 58 to 68 lm / W.

  On the other hand, the variation width of the lamp efficiency in the product A of the present invention is reduced to the range of 63 to 69 lm / W, and the average value of the lamp efficiency is improved from 63 lm / W of the comparative product to 66.5 lm / W. I understood. In addition, it has also been found that the lamp luminous flux rises to a level where the luminous flux value of the lamp 3 seconds after the start-up is 40% or more at the time of steady lighting at room temperature 25 ° C.

  As described above, according to the first embodiment of the present invention, the thermal conductivity of the thermal conductive medium 10 can be increased, the cooling effect of the coldest spot of the arc tube 2 between the lamps can be increased, and thus mass production is possible. Even if the coupling distance varies between lamps, fluctuations in the coldest spot temperature of the arc tube 2 can be suppressed, the variation range of lamp efficiency can be reduced, and the average value can be increased, and the lamp characteristics can be further improved. An excellent and stable quality low-pressure mercury vapor discharge lamp can be obtained.

  In addition, as the heat conductive medium 10, for example, silica may be used in addition to the silicone, and metal powders such as nickel and iron oxide other than aluminum powder may be used. In this embodiment, about 3 g of silicone resin is used as the heat conductive medium, and about 50% of aluminum powder is mixed with the weight of the silicone resin.

  If the metal powder is excessively added, the illuminance directly below, the luminous flux decrease, the lamp weight increases, and the cost increases. On the other hand, if the amount is too small, it is difficult to obtain the effect. Therefore, the amount of metal powder to be encapsulated may be appropriately encapsulated in view of these problems depending on the size and form of the lamp.

  Next, a second embodiment of the present invention will be described with reference to the drawings.

  A bulb-type fluorescent lamp 11 (hereinafter referred to as the present invention product B), which is a second embodiment of the present invention shown in FIG. This is different in that the protruding portion 9 and the portion of the outer tube 7 opposed to the protruding portion 9 are in direct contact with each other. Similar to the above-described embodiment, the protruding portion 9 is embedded with a thermally conductive medium 10 mixed with metal powder.

  With such a configuration, the heat at the coldest spot can be directly transferred to the outer tube 7 and the thermal conductivity can be increased by the heat conductive medium 10 mixed with the metal powder. The fluctuation of the coldest spot temperature can be further suppressed.

  In the product B of the present invention, it was confirmed that the variation range of the lamp efficiency could be further reduced to a range of 67 to 71 lm / W, and the average value further increased to 69 lm / W. It was also found that the rise characteristic of the lamp luminous flux was improved to the same level as that of the product A of the present invention.

  Next, a third embodiment of the present invention will be described with reference to the drawings.

  A bulb-type fluorescent lamp 12 (hereinafter referred to as the present invention product C), which is a third embodiment of the present invention shown in FIG. In the tube 7, a recessed portion 13 that is recessed about 1.0 mm outward is formed at a portion where the protruding portion 9 of the arc tube 2 contacts, and the protruding portion 9 of the arc tube 2 is formed in the recessed portion 13. The difference is that the protrusion 9 and the outer tube 7 which are the coldest spots are in direct thermal contact with each other. Similar to each of the above embodiments, the protruding portion 9 is embedded with a thermally conductive medium 10 mixed with metal powder. The outer surface of the recess 13 of the outer tube 7 protrudes about 1 to 2 mm outward.

  In the product C of the present invention, it was confirmed that the variation width of the lamp efficiency was further reduced to the range of 67 to 71 lm / W, and the average value further increased to 69 lm / W. It was also found that the rise characteristic of the lamp luminous flux was improved to the same level as that of the product A of the present invention. Further, it is possible to relatively easily weld a protruding portion 9 of the arc tube 2 to be described later and the outer tube 7.

  In the products B and C of the present invention, the projection 9 and the outer tube 7 which are the coldest spots of the arc tube 2 are in direct contact with each other by contact, but are welded at the contact portions. The same effect can be obtained. Furthermore, in this case, the strength is increased at the welded portion, and the strength against vibration and impact during lamp transportation can be improved.

  The protrusion 9 of the arc tube 2 is in direct contact with and welded to the outer tube 7. Conventionally, when the protrusion 9 of the arc tube 2 and the outer tube 7 are brought into direct contact with each other, the arc tube 2 is brought into contact by the external impact or the like. Although it was thought to be easily broken, it was found that the strength was improved contrary to expectations. This is because the protruding portion 9 of the arc tube 2 and the outer tube 7 are in direct contact with each other and are welded and further covered with a heat conductive medium made of resin. This is considered to be because the thickness is increased, the strength is maintained, and the resin-made thermally conductive medium has an effect of reducing the impact and the like.

  The present invention can be applied not only to a double spiral arc tube but also to a bulb-type fluorescent lamp using an arc tube in which three U-tubes or four U-tubes are connected. The lamp is provided with a light emitting tube having a spot and an outer tube covering the light emitting tube, and can be effectively applied particularly to a low-pressure mercury vapor discharge lamp that requires temperature control at the coldest spot.

  The present invention can be applied not only to a double spiral arc tube but also to a bulb-type fluorescent lamp using an arc tube in which three U-tubes or four U-tubes are connected. The lamp is provided with a light emitting tube having a spot and an outer tube covering the light emitting tube, and can be effectively applied particularly to a low-pressure mercury vapor discharge lamp that requires temperature control at the coldest spot.

1 is a partially cutaway front view of a bulb-type fluorescent lamp according to a first embodiment of the present invention. Partially cutaway front view of a bulb-type fluorescent lamp according to a second embodiment of the present invention Partially cutaway front view of a bulb-type fluorescent lamp that is a third embodiment of the present invention Partially cutaway front view of a conventional bulb-type fluorescent lamp

Explanation of symbols

2 arc tube 3 holder 4 lighting circuit 5 base 6 case 7 outer tube 9 protrusion 10 heat conductive medium 13 recess

Claims (4)

An arc tube having a pair of electrodes at both ends and having one curved discharge path inside is provided in the outer tube, and the arc tube has a coldest spot planned location that becomes the coldest spot during light emission. And the coldest spot planned location and the portion of the outer tube facing the coldest spot planned location are connected via a resin thermal conductive medium, the thermal conductive medium A low-pressure mercury vapor discharge lamp characterized in that metal powder is mixed. 2. The low-pressure mercury vapor discharge lamp according to claim 1, wherein the planned coldest spot is in direct contact with the outer tube. 2. The low-pressure mercury vapor discharge lamp according to claim 1, wherein the coldest spot expected location and the portion of the outer tube where the coldest spot expected direct contact is fitted and in direct contact. The low-pressure mercury vapor discharge lamp according to any one of claims 2 to 3, wherein a place where the coldest spot is directly in contact with the outer tube is welded.

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