JP4922624B2 - Discharge lamp and manufacturing method thereof - Google Patents

Description

  The present invention relates to a discharge lamp and a method for manufacturing the same, and more particularly to a discharge lamp having a phosphor layer on the inner wall surface of a glass tube and a method for manufacturing the same.

  In a discharge lamp such as a hot cathode tube or a cold cathode tube, a phosphor is uniformly applied to the inner wall of a glass tube provided with electrodes at both ends, and an appropriate amount of mercury (Hg) and argon (Ar) are contained in the glass tube. Alternatively, an inert gas such as neon (Ne) is sealed at a pressure of several tens of Torr.

  The light emission principle of the above-mentioned discharge lamp is that when an electric field is applied between both ends from the outside, the initial electrons existing in the gas are accelerated and collide with the mercury gas atoms and inert gas enclosed in the glass tube to be excited and ionized. Glow discharge is started by causing a chain reaction such as generation of electrons. In addition, the mercury atom with which the electrons collide is excited to emit ultraviolet light (λp = 253.7 nm), and this ultraviolet light excites the phosphor uniformly applied to the inner wall of the glass tube to convert it into visible light, Released to the outside. That's it.

  By the way, as described above, the phosphor layer formed on the inner wall of the glass tube is coated on the inner wall of the glass tube with phosphor slurry in which the phosphor is mixed with a binder for adhering the phosphor to the glass tube. And then dried.

In that case, the binder generally includes a fine particle type using calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) or the like having a particle size of about 1.0 μm or less, and boric acid (B There are low melting point types mainly composed of ₂ O ₃ ), which are used alone or in combination.

  The former fine-particle type uses a binder that fills the gaps between the phosphor particles, and the latter low-melting type uses a binder that has been softened by heat treatment during drying, thereby bonding phosphors to each other or phosphor and glass. To do.

In particular, for the former fine particle type, a method as shown in FIG. 3 has been proposed. That is, phosphor powder 30 having an average particle diameter of 3 to 10 μm and inorganic powder having an average particle diameter of 1/3 or less of the average particle diameter of phosphor powder 30 (for example, calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) A phosphor paste mixed with the powder 31 is applied to the surface of the partition wall 32 and subjected to a firing treatment to obtain a phosphor layer 33.

As a result, the inorganic powder 31 having an extremely large adhesion force compared to gravity enters the relatively large gap between the phosphor powders 30 of the phosphor layer 33 and fills them up. The phosphor layer 33 having a strong adhesive strength is formed on the surface of the partition wall 32 by the intermolecular force acting between the bodies 31 and between the surface of the phosphor powder 30 and the inorganic powder 31 and the surface of the partition wall 32. It can be formed (for example, refer to Patent Document 1).
JP 2000-87025 A

  By the way, in the fine particle type light emitting device, the adhesive strength is enhanced by the intermolecular force acting between the surface comprising the phosphor powder 30 and the inorganic powder 31 and the surface of the partition wall 32. The surface area of the partition wall 32 surface that contacts the surface made of the body 30 and the inorganic powder 31 is defined by the size of the partition wall 32 surface, and it is difficult to obtain an adhesive strength higher than that. Further, there is a problem that the adhesive strength is extremely lowered as the particle size of the phosphor powder 30 is increased.

  In that case, if the adhesive strength of the phosphor layer 33 is insufficient with respect to the surface of the partition wall 32, there arises a problem that the phosphor layer 33 is peeled off from the surface of the partition wall 32 in the manufacturing process.

  As a countermeasure, it is conceivable to increase the mixing ratio of the inorganic powder 31 to the phosphor powder 30 to enhance the adhesive strength. However, the adhesive strength improves as the amount of the inorganic powder 31 serving as a binder increases. However, since the binder affects the optical characteristics, the optical characteristics are deteriorated.

  Therefore, the present invention was devised in view of the above problems, and the object of the present invention is to form the phosphor layer on the inner wall surface of the glass tube of the discharge lamp. It is in ensuring good adhesive strength.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention is a discharge lamp manufacturing method in which electrodes are provided at least at both ends of a glass tube, and a phosphor layer is provided on the inner wall surface of the glass tube. A method of forming a plurality of convex glass structures by applying a glass slurry to an inner surface of the glass tube and firing the method; a surface of the convex glass structure; and the plurality of convex glass structures. Forming the phosphor layer on the inner wall surface of a glass tube composed of the inner surface other than the portion on which the convex glass structure is formed, and the glass slurry contains powdered glass The powder glass is a mixture of a powder glass having a melting point lower than the firing temperature and a powder glass having a melting point higher than the firing temperature, and a powder glass having a melting point lower than the firing temperature at the time of firing is , It is characterized in that the melt to smoothly joined to the glass powder having a melting point higher than the forming temperature and the glass tube.

The invention described in claim 2 of the present invention is characterized in that, in claim 1 , the convex glass structure has a size of 5 to 60 μm.

  According to the present invention, by forming a convex glass structure on the inner surface of the glass tube of the discharge lamp, a glass tube is formed between the surface of the convex glass structure and the inner surface other than the portion where the convex glass structure is formed. An inner wall surface was formed, and a phosphor layer was formed on the inner wall surface. As a result, the contact area between the inner wall surface of the glass tube and the phosphor layer formed on the inner wall surface was increased, and the adhesive strength between them was enhanced.

  When forming the phosphor layer on the inner wall surface of the glass tube of the discharge lamp, the purpose of ensuring good adhesion strength between the inner wall surface of the glass tube and the phosphor layer is convex on the inner surface of the glass tube of the discharge lamp. By forming the glass structure, the inner wall surface of the glass tube is constituted by the surface of the convex glass structure and the inner surface other than the portion where the convex glass structure is formed, and the phosphor layer is formed on the inner wall surface. Realized by forming.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. In addition, since the Example described below is a suitable specific example of this invention, various technically preferable restrictions are attached | subjected, The range of this invention limits this invention especially in the following description. As long as there is no description of that, it is not restricted to these Examples.

Example 1 relating to the method of manufacturing a discharge lamp according to the present invention includes:
First, powder glass having an average particle diameter of 5.2 μm and a softening point of 630 ° C. mainly composed of ZnO, B ₂ O ₃ and SiO ₂ in a 1.0 wt% nitrocellulose binder in which nitrocellulose is dissolved in butyl acetate as a solvent. GP-014 (manufactured by Nippon Electric Glass Co., Ltd.) is mixed at 30 wt%, and this is stirred and dispersed and stirred for 4 to 5 days on a turntable to adjust the glass slurry.

  Next, this glass slurry is applied to the inner wall of a glass tube having an inner diameter of 2 mm, an outer diameter of 3 mm, and a length of 340 mm, and then heat-treated at a temperature of 650 ° C. for 1 minute in an approximately 60% oxygen atmosphere.

  Then, the powder glass existing in the form of particles on the inner wall of the glass tube before the heat treatment is baked and melted by the heat treatment, and is welded to the inner wall of the glass tube to form a structure that is deformed into a particle shape or a convex shape. The size of the convex structure at this time was 5 to 20 μm due to aggregation due to melting of the powder glass particles.

  The inventor prepared three kinds of glass slurries with powder glass concentrations of 10 wt%, 20 wt% and 30 wt%, respectively, and conducted an experiment to form a convex glass structure on the glass tube wall surface by the above process for each glass slurry. Tried.

  As a result, it was confirmed that when a glass slurry having a powder glass concentration of 30 wt% was used, a convex glass structure could be formed most uniformly over the entire inner surface of the glass tube. It has also been found that when the powder glass concentration is higher than 30 wt%, the dispersibility of the powder glass in the glass slurry is deteriorated, and the uniformity of the convex glass structure formed on the inner wall of the glass tube is impaired.

  Next, three types of phosphors that emit light of red (R), green (G), and blue (B) tones on the inner wall of the glass tube on which the convex glass structure is formed, when excited by ultraviolet rays. And an RGB phosphor slurry mixed with a binder, and then heat-treated at a temperature of 650 ° C. for 1 minute and fired.

  In this case, since the firing temperature of the RGB phosphor slurry is the same as the firing temperature of the glass slurry, the convex glass structure previously formed on the inner wall of the glass tube is remelted and fluorescent when the RGB phosphor slurry is fired. It will adhere to the body.

  FIG. 1 is a side view of a discharge lamp produced through the above manufacturing process, and FIG. 2 is a detailed view of part A of FIG. 1 and 2 are also diagrams showing a second embodiment described later. In all the examples, the discharge lamp is a cold cathode discharge lamp.

  From FIG. 1, a phosphor layer 4 is formed on the inner wall surface 3 of the glass tube 2 of the discharge lamp 1. From FIG. 2 showing the inner wall surface 3 and the phosphor layer 4 of the glass tube 2 in more detail, a convex glass structure 5 is formed on the inner wall surface 3 of the glass tube 2, and strictly speaking, the glass tube 2 The substantially inner wall surface is composed of a surface constituted by the surface of each convex glass structure 5 and a surface other than the portion where the convex glass structure 5 is formed.

  Therefore, a substantially glass inner wall surface on which the convex glass structure 5 such as a discharge lamp formed through the above manufacturing process is formed has a convex glass structure 5 like a conventional discharge lamp. The surface area is extremely large compared to the inner wall surface 3 of the glass tube.

  When the phosphor layer 4 is formed by coating the phosphor 7 mixed with the binder 6 on the substantially inner wall surface of the glass tube having an enlarged surface area, the inside of the glass tube is substantially compared with the conventional discharge lamp. It is clear that the contact area between the wall surface and the phosphor layer 4 becomes extremely large, and the adhesive strength between them is remarkably enhanced.

  Hereinafter, an evaluation test method and an evaluation result of the adhesive strength between the inner wall surface of the glass tube on which the convex glass structure is formed and the phosphor layer of the discharge lamp produced through the above manufacturing process will be described.

  In the evaluation test method, the discharge lamp is accommodated in a box-type case having a width of 6 mm, a length of 300 mm, and a depth of 10 mm, and both ends are fixed to the side plate portions of the case. Then, a nozzle injection port of an air gun is provided at a position 100 mm away from the longitudinal center line above the longitudinal center of the discharge lamp, and nitrogen gas is blown onto the discharge lamp at a discharge pressure of 3.5 kg for 30 seconds.

  Then, since the discharge lamp accommodated in the case receives the wind pressure of nitrogen gas and vibrates and collides, it is possible to evaluate the adhesive strength by observing whether the phosphor layer peels off the inner wall of the glass tube after the test. it can.

  Therefore, as a result of putting the discharge lamp of this example and five conventional discharge lamps each having no convex glass structure on the inner wall of the glass tube into the evaluation test, all five of the conventional discharge lamps are contained in the glass tube. Although peeling of the wall surface and the phosphor layer was confirmed, no peeling was confirmed in the discharge lamp of this example.

  Next, the optical characteristics of the discharge lamp of this example were measured. As a result, it was confirmed that a luminous flux of 153 lm (lamp current 6 mA) equivalent to that of a conventional discharge lamp can be secured.

  From the above, it has been confirmed that the discharge lamp produced through the above manufacturing process has good reliability and exhibits good characteristics in both discharge and light emission.

In Example 2 according to the present invention, powder glass ASF1495 (manufactured by Asahi Glass Co., Ltd.) and ZnO, B having an average particle size of 2.2 μm and a softening point of 595 ° C. as the main components are ZnO and B ₂ O _3. An equal weight mixture of powdered glass ASF1620M (Asahi Glass Co., Ltd.) having an average particle size of 25.0 μm and a softening point of 657 ° C. containing ₂ O ₃ and SiO ₂ as main components was used.

  This mixed powder glass was mixed with 30 wt% in a 1.0 wt% nitrocellulose binder in which nitrocellulose was dissolved in butyl acetate as a solvent in the same manner as in Example 1 above, and this was stirred and dispersed on a turntable for 4 to 5 days. The glass slurry is adjusted by stirring.

  Next, this glass slurry is applied to the inner wall of a glass tube having an inner diameter of 2 mm, an outer diameter of 3 mm, and a length of 340 mm, and then heat-treated at a temperature of 650 ° C. for 1 minute in an approximately 60% oxygen atmosphere.

  Then, since the powder glass ASF1495 has a smaller particle size than the ASF1620M and the softening point is lower than the firing temperature, what was present in the form of particles on the inner wall of the glass tube before the heat treatment is fired and melted by the heat treatment, Since powder glass ASF1620M has a particle size larger than ASF1495 and a softening point higher than the firing temperature, it maintains the shape before firing without melting.

  Therefore, in this case, ASF1620M serves as a column of convex glass structure formed on the inner wall of the glass tube, and ASF1495 plays a role of a smoothing agent that smoothes the shape of the convex glass structure together with a binder that supports the column. ing. The size of the convex structure at this time was 10 to 60 μm due to aggregation of powder glass particles and the like.

  In addition, since the process after fluorescent substance application is the same as the process of producing the discharge lamp of Example 1, the description is omitted.

  As a result of evaluating and testing five discharge lamps of this example by the same method as in Example 1, no separation between the inner wall surface of the glass tube and the phosphor layer was confirmed. It was confirmed that a value equivalent to that of the conventional discharge lamp could be secured for the luminous flux.

  That is, it was confirmed that the discharge lamp of this example produced through the above manufacturing process also has the same reliability and optical characteristics as the discharge lamp of Example 1.

  Example 3 according to the present invention was prepared under substantially the same conditions as in Example 1 described above, and the only difference was that an RGB phosphor slurry containing no binder was used. Also in this example, five discharge lamps were prepared and put into an evaluation test together with five conventional discharge lamps.

  The evaluation test method was carried out by substantially the same method as in Example 1 and Example 2, except that the nitrogen gas blowing time for the discharge lamp was set to 10 seconds.

  Therefore, as a result after the evaluation test, peeling of the inner wall surface of the glass tube and the phosphor layer was confirmed in three conventional discharge lamps, and peeling was confirmed in two discharge lamps of this example.

  As for the optical characteristics, the luminous flux of the conventional discharge lamp is 158 lm (lamp current 6 mA), whereas the luminous flux of the discharge lamp of this embodiment is 160 lm (lamp current 6 mA).

  From the above, regarding the adhesive strength between the inner wall surface of the glass tube and the phosphor layer, the discharge lamp of this example has the same performance as the conventional discharge lamp, and the optical characteristics are compared with the conventional discharge lamp. It can be seen that the luminous flux is improved by about 1% or more. This is considered to be a result of removing factors that affect the optical characteristics by using the RGB phosphor slurry not containing the binder.

  In Examples 1 to 3, the phosphor slurry is not necessarily required to contain all the phosphors (R), (G), and (B), and may be used alone or in order to obtain a desired emission color of the discharge lamp. Two or more combinations may be used.

  As described above, the discharge lamp of the present invention has a convex glass structure formed on the inner wall surface of the glass tube of the discharge lamp to increase the substantial surface area of the inner wall surface, and the binder formed on the inner wall surface. The contact area with the phosphor layer mixed with was increased.

  As a result, a luminous flux equivalent to that of a conventional discharge lamp that does not form a convex glass structure on the inner wall of the glass tube can be secured, and the adhesive strength between the glass inner wall surface and the phosphor layer is enhanced compared to the conventional discharge lamp. Thus, a discharge lamp with improved reliability can be realized.

  Further, a convex glass structure is formed on the inner wall surface of the glass tube of the discharge lamp to increase the substantial surface area of the inner wall surface, and the contact area with the phosphor layer not mixed with the binder formed on the inner wall surface is increased. I tried to make it bigger.

  As a result, the adhesive strength between the glass inner wall surface and the phosphor layer equivalent to that of a conventional discharge lamp that does not form a convex glass structure on the inner wall of the glass tube can be secured, and the luminous flux can be increased as compared with the conventional discharge lamp. Thus, a discharge lamp with improved optical characteristics can be realized. It has excellent effects such as.

It is a side view of the discharge lamp of Example 1 and Example 2 concerning this invention. FIG. 2 is a detailed view of part A in FIG. 1. It is a fragmentary sectional view of the conventional discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge lamp 2 Glass tube 3 Inner wall surface 4 Phosphor layer 5 Convex glass structure 6 Binder 7 Phosphor

Claims (2)

A method of manufacturing a discharge lamp in which electrodes are disposed at at least both ends of a glass tube, and a phosphor layer is provided on an inner wall surface of the glass tube, wherein a glass slurry is applied to the inner surface of the glass tube and fired. A step of forming a plurality of convex glass structures, and a surface of the convex glass structure and the inner surface other than a portion where the convex glass structure is formed between the plurality of convex glass structures. Forming the phosphor layer on the inner wall surface of the glass tube, and the glass slurry contains powdered glass, the powdered glass having a melting point lower than the firing temperature, It is a mixture of powder glass having a melting point higher than the firing temperature, and a powder glass having a melting point lower than the firing temperature at the time of firing slides the powder glass having a melting point higher than the firing temperature and the glass tube. Method for producing a discharge lamp, characterized in that it is melted so as to bond to. 2. The method of manufacturing a discharge lamp according to claim 1 , wherein the convex glass structure has a size of 5 to 60 [mu] m.

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