JPS6238817B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a phosphor coating on the inner surface of a U-shaped glass tube.

Recently, a small fluorescent lamp made of a glass tube formed into a U-shape has been proposed. This small fluorescent lamp has a phosphor coating formed on the inner surface of a glass tube and has a single-cap structure. To form such a phosphor coating, a phosphor suspension is applied to the inner surface of a U-shaped glass tube, and the phosphor suspension is dried naturally or forcefully. By applying the method of drying a phosphor suspension applied to a straight glass tube and introducing air etc. into the glass tube from only one end of the opening of the U-shaped glass tube, the phosphor suspension can be dried. There was a problem in that even if the suspension was dried, a homogeneous and smooth phosphor coating could not be obtained.

The present invention has been made in view of these problems and provides an apparatus that can uniformly and smoothly form a phosphor coating on the inner surface of a U-shaped glass tube.

FIG. 1 shows an example of a phosphor film forming apparatus according to an embodiment of the present invention, in which a U-shaped glass tube 1 is held and fixed vertically in a holder 2 with both openings facing downward. The drying gas introduction device 3 includes a glass tube 1
is inserted into both openings of the tube, and the drying gas,
For example, a nozzle 3a that introduces air etc. into the pipe.
and a holder 3b that fixes the upper end of this nozzle.
, a bracket 3c that holds the nozzle 3a movably in the vertical direction, a holder 3d that fixes the lower end of the nozzle 3a, moves the nozzle 3a in the vertical direction, and inserts the nozzle 3a into both openings of the glass tube 1. and electromagnetic valves 3f and 3g that are connected to the lower end of the nozzle 3a and guide the drying gas to the nozzle 3a.

First, mold a glass tube into a U-shape.
A U-shaped glass tube as shown in FIG. 2 is obtained. Thereafter, a phosphor suspension is applied to the inner surface of this U-shaped glass tube.

As shown in FIG. 1, the U-shaped glass tube 1 is placed so that both openings are in the lower position.
It is held in holder 2. Next, the nozzle 3a is inserted into the glass tube 1 from both openings by operating the air cylinder 3e, and the solenoid valve 3f is opened for 3 seconds to flow a predetermined amount of drying air into the tube, and then closed. At the same time, the solenoid valve 3g is opened, a predetermined amount of drying air is allowed to flow into the pipe for 3 seconds, and then closed. By repeating this operation, the phosphor suspension gradually dries from the top (bent part) to the bottom of the glass tube 1. When the suspension at the bottom has completely dried, both solenoid valves 3f,
3g are closed together, the operation of the air cylinder 3e is stopped, and the nozzle 3a is lowered and taken out from both openings of the glass tube 1.

According to this device, since drying air is alternately introduced into the glass tube 1 from both openings, the U
The phosphor suspension applied to the inner surface of the bent portion of the letter-shaped glass tube 1 is quickly dried, and the phosphor suspension applied to the inner surfaces of both legs extending downward from both sides of the bent portion is dried quickly. It dries from the top to the bottom at almost the same speed. As a result, a homogeneous and smooth phosphor coating is formed on the inner surface of the glass tube 1. When an 18W U-shaped fluorescent lamp with a single cap structure was fabricated by providing electrodes at both ends of the glass tube, the initial luminous flux was approximately 900 m, and the luminous flux attenuation rate was 96%, the desired values.

On the other hand, in the method of naturally drying the phosphor suspension applied to the inner surface of a U-shaped glass tube, the phosphor suspension applied to the inner surface of the bent portion of the glass tube is dried. Since it flows to the lower part of the glass tube, the phosphor coating formed in that part becomes locally thinner and has an uneven thickness. In addition, a U-shaped fluorescent lamp using this glass tube and having the same structure and wattage as above had an initial luminous flux of about 864 m and a luminous flux attenuation rate of 92%, making it impossible to obtain the desired values.

Furthermore, as another method, drying air was introduced using a nozzle from only one side of the opening of a U-shaped glass tube whose inner surface was coated with a phosphor suspension.
The phosphor suspension on the leg side without the nozzle dries faster than that on the leg side with the nozzle inserted, and the phosphor coating on the former side is formed thicker than that on the latter side. The thickness of the light body coating varied.

As explained above, according to the present invention, a phosphor coating can be uniformly and smoothly formed on the inner surface of a U-shaped glass tube. The U-shaped fluorescent lamp obtained using the device of the present invention also exhibits desired values of luminous flux and luminous flux attenuation rate, and is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a phosphor film forming apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view showing an example of a U-shaped glass tube. 1...Glass tube, 2...Holder, 3a...Nozzle, 3b, 3d...Holder, 3e...Air cylinder.

Claims (1)

[Claims] 1 A holder that holds a U-shaped glass tube whose inner surface is coated with a phosphor suspension with both openings facing downward; and a holder that injects drying gas into the glass tube from both openings of the glass tube. A phosphor coating forming apparatus comprising: a nozzle that forms a phosphor coating on the inner surface of the glass tube by alternately introducing nozzles.