JPH0412579B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for manufacturing a fluorescent lamp, and more particularly to an improvement in the process of forming a protective film on the inner surface of a bulb. [Technical background of the invention and its problems] Conventionally, in the production of fluorescent lamps, both the inside and outside of the glass tube are washed with water to remove dust and other impurities, and after drying, a phosphor suspension is applied to the inside of the glass tube. A fluorescent film was formed by applying a liquid, drying it, and baking it. In recent years, in order to protect the phosphor from the alkaline components in the glass, a protective film made of inorganic fine powder such as alumina or silica has been formed on the inner surface of the glass tube.
A fluorescent film is now formed on this protective film. In this case, when cleaning the glass tube, the holding method,
If the cleaning method and drying method were to be operated without any restrictions as before, the resulting protective film would be in very poor condition, and the film thickness would often be uneven due to uneven drying. When lamps with a protective film are lit, mercury adheres to uneven areas, creating thin band-like patterns, which not only spoils the appearance but also shortens the lamp's lifespan. [Object of the Invention] The present invention forms a uniform protective film and forms a fluorescent film on it in industrial assembly line operations, thereby preventing contamination of the protective film by mercury and shortening due to uneven thickness of the protective film. The purpose of the present invention is to provide a method for manufacturing a fluorescent lamp that has no lifetime. [Summary of the invention] A glass tube is oriented vertically and supported at both ends, the inner surface of the tube is washed with water without wetting the outer surface, and then a suspension of inorganic fine powder is applied to the inner surface to form a protective film. This is a method of uniformly drying the suspension to obtain a uniform protective film. [Embodiments of the Invention] The inventor investigated the reason why the protective film is formed non-uniformly and found that the reason is local non-uniformity in the temperature of the glass tube during drying, and that the cause is heat conduction to the chuck. It was discovered that this was caused by the heat of evaporation of the washing water locally remaining on the outer surface of the glass tube.
We succeeded in eliminating the cause of the defect by improving the chuck position and cleaning method. Hereinafter, details of the present invention will be explained with reference to illustrated embodiments. The glass tube used in this example has a straight tube shape as shown in FIG. 1, and both ends are baked and rounded and curved slightly inward. First, as shown in FIG. 1, the glass tube 1 is turned vertically and the curved part 11 at the upper end is inserted into the receiving hole 21 of the plate-shaped upper chuck 2, and the L-shaped lower chuck 3 is inserted into the spring. 31 to lock the locking claw 32 to the curved portion 12 at the lower end of the glass tube 1. Next, as shown in Fig. 2, this glass tube 1
The solenoid valve 41 linked to this feeding is opened, and the nozzle 4 facing the upper end surface of the glass tube 1 is sent to the cleaning position while being attached to both chucks 2 and 3.
Cleaning water 43 is injected into the pipe 1 from 2. At this time, by the action of the solenoid valve 41, the glass tube 1
Since the water 43 is not sprayed until the glass tube 1 directly faces the nozzle 42, and the position and structure of the nozzle 42 are appropriate, the cleaning water 43 is sprayed only onto the inner surface of the glass tube 1, and is sprayed onto the outer surface. never be done. Even if for some reason a small amount of cleaning water 43 becomes mist or drops and scatters, the upper chuck 2 will form a plate shape and the glass tube 1
Since it covers the upper curved part 11, the chuck 2 prevents fog and water droplets from flowing into the glass tube 1.
Will not adhere to external surfaces. Next, as shown in Fig. 3, this glass tube 1
is sent to the drying position while attached to both chucks 2 and 3, and drying air 52 is blown into the tube 1 from the nozzle 51 facing the upper end surface of the glass tube 1.
Dry inside. This drying process is performed to reduce the cleaning water 43 remaining on the inner surface of the glass tube 1, and as will be described later, complete drying is not necessarily necessary, so the temperature and air volume of the drying air 52 can be freely adjusted. Furthermore, in a dry atmosphere, this drying step may be completely omitted. Next, as shown in FIG.
is attached to both the chucks 2 and 3 mentioned above, and sent to the coating position, and a suspension 62 of inorganic fine powder is injected onto the inner surface of the tube 1 using an appropriate means, for example, a nozzle 61 from the upper end surface of the glass tube 1. Apply evenly. This suspension 62 is, for example, a suspension of fine gamma alumia powder called colloidal alumina with a particle size of 5 to 30 mμ in pure water, and by applying this suspension a uniform coating film 63 of a desired thickness can be obtained. Moreover, since the solvent of this suspension 62 is water, some amount of cleaning water 4 is applied to the inner surface of the glass tube 1 on the entire surface or locally during application.
Even if 3 remains, there is no particular harm as the recovered suspension 62 will simply become diluted. Next, as shown in FIG.
are sent to the drying position while attached to both chucks 2 and 3, and drying air 73 heated to an appropriate temperature (described later) by a heater 72 is introduced into the tube 1 from a nozzle 71 facing the upper end surface of the glass tube 1. The suspended coating film 63 is dried to form the protective film 8. At this time, the outer surface of the glass tube 1 is completely dry.
In addition, since the chucks 2 and 3 are not on the straight part of the tube 1, unlike the conventional drying method in which the outer surface is wet,
The local temperature of the glass tube 1 is uniform and therefore
The drying rate of the coating film 63 is uniform over the entire surface, and the obtained protective film 8 is also uniform in film thickness and particle size distribution. Next, as shown in FIG. 6, a fluorescent film 9 is formed on the protective film 8 by a conventional method, and a fluorescent lamp is further constructed. As described above, according to the method of this embodiment, the protective film 8
Since the film thickness and the particle size distribution of the fine powder are uniform, the obtained fluorescent lamp does not suffer from poor appearance due to mercury adhesion during lighting and does not have a short life. Further, when drying the inorganic fine powder suspension coating film 63, the blowing time, wind speed, and temperature of the drying air 73 have a large effect on the state of the protective film 8. The experimental values for this relationship are shown in the table below.

〔Effect of the invention〕

The method for manufacturing a fluorescent lamp of the present invention involves supporting a glass tube vertically at both ends, washing the inner surface with water without wetting the outer surface of the glass tube, and then applying a suspension of inorganic fine powder to the inner surface of the glass tube. By drying the suspension, a protective film is formed, and a fluorescent film is formed on this protective film.The outer surface of the glass tube is in a dry state when the suspension is dried. There is no local temperature unevenness, and since the chuck is not in contact with a straight section, there is no local cooling due to conduction, so the suspension coating film dries uniformly.
There is no non-uniformity in film thickness or particle size distribution, and therefore the poor appearance and short life of fluorescent lamps caused by this are eliminated.

[Brief explanation of drawings]

1 to 6 are explanatory drawings showing one embodiment of the method for manufacturing a fluorescent lamp of the present invention in the order of steps. 1...Glass tube, 2, 3...Chuck, 43...Washing water, 52,73...Drying air, 62...Suspension liquid,
63... Paint film, 8... Protective film, 9... Fluorescent film.

Claims (1)

[Claims] 1. Support a glass tube for a fluorescent lamp vertically at both ends, wash the inner surface of the glass tube with water without wetting the outer surface, and then apply a suspension of inorganic fine powder to the inner surface of the glass tube and dry it. 1. A method for manufacturing a fluorescent lamp, comprising: forming a protective film on the protective film; and forming a fluorescent film on the protective film.