JPS6154137A - Coating method of phosphor suspension - Google Patents

Abstract

PURPOSE:To prevent the remainder of coating and unevenness of coating when coating the inner surface of a U-shaped glass tube with phosphor suspension by making the openings of both feet sections of the glass tube and spraying the suspension whose spraying fluid speed is different from each of the openings. CONSTITUTION:A U-shaped glass tube 1 used for a fluorescent lamp is retained so that the opening ends 11a and 12a of individual feet sections 11 and 12 can be located downward. Then, the tube is opposed to the opening ends 11a and 12a and connected to a coomon manifold 2. Simultaneously, suspension spraying nozzle 21 is larger than the inner diameter of the other spraying 22 are set and the inner surface of the glass tube 1 is coated with phosphor suspension 3 by spraying. As aresult, since there occurs a difference in each fluid speed of the suspension 3 sprayed in both feet sections 11 and 12 of the glass tube 1, the suspension is spread well all over the internal circumference surface and the remainder coating and unevenness of coating can be removed with comparatively simply structure.

Description

[Detailed description of the invention] [Technical field of invention] This invention is applied to the manufacturing process of U-shaped fluorescent lamps.

This invention relates to a method of applying a phosphor suspension to the inner surface of a U-shaped glass tube.

[Prior art] Normally, in the process of manufacturing a U-shaped fluorescent lamp, in order to apply a phosphor suspension (hereinafter simply referred to as suspension) to the inner surface of a U-shaped glass tube, the U-shaped glass tube is first coated. Hold the tube so that the open ends of the legs face upward (119) and inject the suspension into the glass tube between the legs.

A method is used in which the inside of a glass tube is filled with a suspension, the glass tube is turned over, the suspension inside is poured out, and the tube is dried with the front end of one leg facing down.

In such conventional coating methods, when mass-produced coating is attempted, it is necessary to have a mechanism that accurately fills the glass tube with the suspension without leaking it to the outside, and a mechanism that allows the suspension to be filled inside the glass tube. It is difficult to develop a mechanism for inverting a glass tube without causing the suspension to scatter around, and a coating device with a complicated structure is inevitably required. In order to solve this problem, the applicant of the present invention 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. In the device proposed in this patent application No. 58-24'5956, 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. 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. In particular, the manufacturing of high-output fluorescent lamps requires a process of forming an alumina layer on the inner surface of the glass tube and then applying a suspension on top of the alumina layer. Due to the influence of the suspension, the wettability of the suspension against the inner surface of the glass tube is poor.
There was a problem in which the occurrence of some degree of unpainted defects was unavoidable.

[Summary of the invention]

This invention has been made in view of the above points, and provides a coating method that can efficiently coat a phosphor suspension onto the inner surface of a U-shaped glass tube using a simple mechanism. Specifically, a U-shaped glass tube is held with the open ends of both legs facing downward, and the phosphor suspension is injected into the glass tube at different injection flow rates across each opening. This is a characteristic feature.

[Fruit of invention 1! Example i] Hereinafter, examples of the coating method of the present invention will be described with reference to the drawings.

The figure shows an example of the coating method of this invention.
1) is a U-shaped glass tube, as shown in Figure 1.
force, O leg (1υ, opening end of a2 (11a), (1
2a) is held downward with a ratchet. And the leg circle above.

Two r-diameter 2 nozzles with liquid jets are placed opposite the opening ends (11a) and (12a) of α2, respectively, c! 2, each spray 1 village nozzle C! υ, c2a
J: Inject one drop of the 5 suspension (3) into the U-shaped glass tube full. At this time, the two injection nozzles Qυ and 4 are each connected to a common manifold (2) as shown in Figure 1, and the inner diameter of one injection nozzle 2+1 is larger than the inner diameter of the other injection nozzle @. Leave the suspension (3)
There is a difference in the flow resistance when the liquid passes through each nozzle CD, @, and the flow velocity of the suspension (3) injected from the injection nozzle Cυ with a larger inner diameter is faster than that of the injection nozzle with a smaller inner diameter. The flow rate of the suspension (3) injected into the U-shaped glass tube (1) from each injection nozzle port υ is higher than that of the suspension (3) that is It shows the behavior as shown, and flows down along the tube wall of the leg uz on the side facing the injection nozzle @. Therefore, the inner surface of the leg 113 of the U-shaped glass tube +1) is covered with the suspension (3).
), so there are no unpainted areas. On the other hand, @ injection nozzle c with a large injection flow velocity of the turbid liquid (3)! The inside of the leg portion (11) on the side facing the plate is filled with the suspension liquid (3).

Since the filled suspension (3) passes over the top αj of the U-shape and flows into the leg u on the opposite side, there will be no unpainted area in this area as well.

In the coating method of the present invention as described above, it is important to differentiate the injection flow rates of the suspension (3) injected into both legs (kll and (I3) of the U-shaped glass tube (1). If suspension 1 (31) is injected from both legs at the same injection speed, naturally both suspensions (31
) collide. Bubbles are generated at the part where the suspension '(3) collides with the surrounding air, but the suspension (3)
When the collision occurs near the top αj of the IJ-shaped glass tube (tl), the bubbles generated here become trapped at the top 0, stopping the injection of the suspension (3), and removing the excess from the inside of the IJ-shaped glass tube (11). Even after the suspension (3) is allowed to flow down, it remains attached to the top 031 on one side, resulting in uneven coating after drying.Both legs of the U-shaped glass tube (1) (11),
If we make a difference in the injection and flow speeds of each suspension (3) injected into a'a, the position where the injected suspension (3) collides will be the leg on the side where it was injected at a lower flow rate. Since the temperature is within 0D, the bubbles generated here are swept away by the suspension liquid (3) with a high flow velocity flowing from the opposite leg part α and flow down.) The injection of the suspension liquid (3) Since there are no bubbles left inside the U-shaped glass tube (1) when the coating is stopped, uneven coating will not occur.

〔Effect of the invention〕

As described above, when applying a phosphor suspension to the inner surface of a U-shaped glass tube, the U-shaped glass tube is held with the front ends of both legs facing downward, and each opening is Since we use a method in which the phosphor suspension is injected into a glass tube at different injection flow rates, there is no possibility of uncoated areas or uneven coating defects, and also when applying in mass production.

This has the advantage that it can be done using a device with a relatively simple structure.

[Brief explanation of drawings]

The figure is a schematic configuration diagram for explaining the present invention in detail. In the figure, (1) is a U-shaped glass tube, and (3) is a phosphor! @
Turbid liquid, +lυ, α2 is the leg, Q3 is the top, Clυ,
0 is the injection nozzle.

Claims (1)

[Claims] When applying a phosphor suspension to the inner surface of a U-shaped glass tube with both legs open, the openings of both legs of the glass tube are positioned downward, and the jet flow speeds are different from each other from each opening. A method for applying a phosphor suspension, characterized in that the phosphor suspension is sprayed toward the top of a glass tube.