JPS61239543A - Coating method for fluorescent material suspension - Google Patents

Abstract

PURPOSE:To eliminate the coating miss by positioning the open end of the foot section of U-shaped glass tube below then blowing steam through one opening to moist the interior of glass tube thereafter ejecting suspension through the other opening toward the top section of the glass tube. CONSTITUTION:U-shaped glass tube 1 having open end sections at both foot sections 11, 12 is held while directing the open section downward then steam is blown from steam generator 2 to the opening of one foot section 11. Water is filled in said steam generator 2 and heated through a heater 2 to predetermined temperature to blow out steam through a blow-out port 23. Alternately, suspension 4 is ejected through the opening of foot section 12 at the opposite side from said foot section 11 into said glass tube 1. The suspension 4 will flow down to the foot section 11 side to be applied entirely over the inner face of the glass tube 1. Consequently, coating miss will scarcely occur.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to the manufacturing process of U-shaped fluorescent lamps.

Related to a method for applying a phosphor suspension to the inner surface of a U-shaped glass tube [Prior art] Usually, in the manufacturing process of a U-shaped fluorescent lamp, a phosphor suspension is applied to the inner surface of a U-shaped glass tube. To apply a suspension (abbreviated as "suspension" in the second half of V), first hold a U-shaped glass tube with the open ends of the legs facing upward, and pour the suspension from the open ends of the nine legs. The method used is to inject it into a glass tube, fill the first glass tube with the suspension, and then turn the glass tube upside down to pour out the suspension and dry it with the open ends of the two legs facing down. ing.

In such conventional coating methods, IA:.

When attempting to apply the suspension to the outside, the glass tube must be filled with an accurate filling mechanism and the glass tube filled with the suspension must not be leaked to the outside. It is difficult to create a mechanism to turn it over without causing it to scatter.
A coating device with a complicated structure is inevitably required. In order to solve this problem, the present applicant has published Japanese Patent Application No. 58-245956 to effectively apply a suspension to the inner surface of a U-shaped glass tube.

We also propose a coating device with a simple structure. This special application was made in 1984-245! In the device proposed in No. 956, U
Application is carried out by holding a letter-shaped glass tube with the open end of the leg facing downward, and injecting the suspension into the glass tube from the open end of one leg and letting it flow down from the open end of the other leg. Since the mechanism is such that there is no need to invert the glass tube, the device has a simple structure.

[Problem that the invention seeks to solve]

However, when applying the suspension by spraying it from the end of one leg of a U-shaped glass tube, it is easy to leave uncoated areas on the inner surface of the leg on the opposite side of the leg from which the suspension is sprayed. There is a problem. Normally, the above suspension uses water as a solvent, so it does not have very good wettability on a dry glass surface. If the application method involves spraying the liquid and letting it flow down the other leg, there is no problem because the leg on the side to be sprayed will be filled with the suspension, but the leg on the opposite side will just have the suspension flowing down naturally. Therefore, it is easy to leave paint marks behind.

[Means to solve the problem]

The purpose of this invention is to solve the above-mentioned problem.The opening end of the leg of a U-shaped glass tube is positioned downward, and water vapor is blown into one opening to moisten the inside of the glass tube. It is characterized in that the suspension is injected from one opening toward the top of the glass tube. The present invention provides a method for efficiently applying a suspension flow inside a U-shaped glass tube.

[Effect]

According to the coating method of the present invention as described above, when the suspension is injected into the U-shaped glass tube, the inner surface of the leg on the opposite side to which the suspension is injected is sufficiently moistened with water vapor, so that water can be used as a solvent. The suspension is in a state where it is very easy to wet, so it is difficult for defects to leave uncoated areas.

〔Example〕

Hereinafter, the method of the present invention will be explained with reference to the drawings.

First, as shown in FIG. Steam is blown into the opening by a steam generator (2).This steam generator (2) contains water QD inside and generates a shear heater 02.
It is heated to a constant temperature and steam is blown out from the steam outlet aa+.

Next, as shown in FIG. 2, water vapor was blown into m;
The suspension (4) is injected into the U-shaped glass tube (1) by the injection nozzle (3) from the opening of the leg +13 on the opposite side to the leg (Ill).The injected suspension (4) flows down to the leg [11j side and is applied to the entire inner surface of the U-shaped glass tube flll. Thereafter, it is dried in a conventional manner to form a phosphor layer on the inner surface of the U-shaped glass tube.

The inner diameter is 15 m using the coating method of the present invention as described above.

As a result of coating the phosphor suspension on the inner surface of a U-shaped glass tube with a length of 150 mm, there was no occurrence of defects due to the intermediate coating remaining after 1000 tubes.

In addition, in the method of the present invention as described above, the amount of water vapor blown into the U-shaped glass tube (1) is important; if it is small, the wettability of the suspension to the glass surface will not be sufficiently improved; If the amount is too high, water droplets will adhere to the inner surface of the U-shaped glass tube (1) and will be mixed into the suspension, making the suspension thinner. The amount of water vapor, □, is the temperature of the water in the steam generator (2), and the distance between the steam outlet row and the open end of the leg aυ of the U-shaped glass tube (1).

The optimum value can be maintained by appropriately setting the blowing time.

〔Effect of the invention〕

As explained above, in the method of the present invention, when applying a phosphor suspension to the inner surface of a U-shaped glass tube,
'Position the openings of both legs of the U-shaped glass tube downward, and blow water vapor through one opening to moisten the inner surface of the glass tube, and then direct the phosphor suspension toward the top of the glass tube through the other opening. This has the advantage that there are almost no uncoated defects.

[Brief explanation of the drawing]

Figures 1 and 2 are for explaining the coating method of the invention. In Figure 9, (1) is a U-shaped glass tube, (2) is a steam generator, and (3) is an injection nozzle. . Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] When applying a phosphor suspension to the inner surface of a U-shaped glass tube with both legs opened, the openings of both legs of the glass tube are positioned downward, and water vapor is blown through one opening to coat the inner surface of the glass tube. 1. A method for applying a phosphor suspension, comprising: wetting the glass tube, and then spraying the phosphor suspension toward the top of a glass tube from the other opening.