JPS5918108B2 - Keiko Lamp Nosaident Souhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for electrostatically coating a phosphor on the inner surface of a glass bulb for a fluorescent lamp.

Conventionally, to coat a phosphor on the inner surface of a glass bulb for a fluorescent lamp, butyl acetate was used, a solution with nitrocellulose as a binder, or city water was used, and phosphor was coated in an aqueous solution with a water-soluble binder. A wet coating method has been implemented in which the luminous material 3 is dispersed and suspended and such a suspension is poured into a glass tube.

However, such a wet coating method requires a large amount of equipment and time to dry butyl acetate and water, and also requires 50% of the binder.
Must be removed by firing at 00~600℃, electric power,
In addition to consuming a large amount of energy such as gas, the firing process has a large effect on the luminance of the phosphor, the lamp luminous flux, and the maintenance rate, making it difficult to manage. In order to eliminate these drawbacks, a method for dry coating the phosphor inside the glass bulb is required, and research has been conducted on 1θ electrostatic coating methods for the phosphor. However, fluorescent lamps have a narrow bulb diameter of 25 to 38 mm and a tube length in the range of 300 to 240,077 Em, making it difficult to obtain a paint film with uniform thickness and strong adhesion over the entire length. However, a perfect "5" product has not yet been created.The present invention was made in view of these circumstances, and it not only applies a coating with a uniform thickness over the length of the valve, but also increases the adhesion strength. It is something.

0 As a result of various experiments, it was found that the uniformity and adhesion strength of the coating largely depended on the electrostatic charge of the powder, and that all phosphor powders had a positive electrostatic charge of 6 to 8 kV. I found out.

In order to electrostatically deposit the powder and increase the uniformity and adhesion strength of the coating, it is necessary to apply a high voltage of polarity opposite to the polarity of the charged charge of the τ powder to the bulb side. Therefore, in a coating equipment equipped with a roller for rotating the valve, a linear burner for heating, and a phosphor injection nozzle that can move freely back and forth, the burner is in the negative direction and the nozzle is in the positive direction, so that the paint is heated approximately 20 to 25 km.
An experiment was conducted in which a high voltage of V was applied, the bulb was placed on a rotating roller, and the bulb was rotated and heated while the phosphor was sprayed from the nozzle to perform coating.

First, FIG. 1 shows the state of adhesion and film thickness of the phosphor 3 when the nozzle 2 is inserted into the bulb 1, the nozzle 2 is fixed, and the phosphor 3 is ejected.

The phosphor 3 is located approximately 3 to 5 crnζ- in front of the tip of the nozzle 2.
A large amount of phosphor 3 adheres over a range of about 20 to 30 cm from the position of , and the amount of adhesion is extremely small in front of it, so the thickness of the phosphor film 4 is thicker on the insertion end side and thinner on the other end side. It becomes thinner.

In addition, approximately 3 to 5 mm forward from the tip of nozzle 2. The reason why the phosphor 3 hardly sticks in this range is that in this range, the force of the phosphor 3 to adhere to the inner surface of the bulb 1 due to electrostatic force is greater than the pressure of the phosphor jet air from the nozzle 2. This seems to be because, since the phosphor 3 is stronger, even if the phosphor 3 tries to adhere to this part, it will be blown away by this air pressure. In this part, the air directly hits the inner surface of the valve 1. In the above case, the adhesion strength of the phosphor film 4 was strong in the thickly adhered parts, and weak in other parts. In this state, it cannot be put to practical use, so
Next, we experimented by moving the nozzle, and as shown in Figure 2, we inserted the nozzle 2 close to the other end of the bulb 1, and while moving the nozzle 2 back at a constant speed, It has been found that the thickness of the phosphor film 4 becomes more uniform than in the case described above.

Moreover, the film strength was strong overall and suitable for practical use. However, in this case, as shown in FIG. 3, if the ejection of the phosphor 3 was stopped just before the nozzle 2 exited from one end of the bulb 1, a phenomenon occurred in which the film thickness in front of the nozzle 2 became thinner. .

When used as a lamp, the thin part of the film would be in contact with the electrodes, making the electrodes transparent and the cathode spots appearing bluish-white, making them extremely unsightly. Therefore, in order to improve this drawback, as shown in Fig. 4, we tried spraying the phosphor 3 until the nozzle 2 came out from one end of the bulb 1, but the improvement effect was large, although the improvement was only slight. I stopped talking. In order to eliminate this drawback, the nozzle shape, dimensions,
Experiments were repeated by variously changing the injection air pressure, but no favorable results were obtained. However, as shown in FIG. 5, by stopping the nozzle 2 for about 0.5 to 1 second just before the nozzle 2 that is being retreated exits from one end of the bulb 1, and continuously spraying the phosphor 3, It has been found that the thickness of the phosphor film 4 is uniform and the adhesion strength is strong throughout.

By the way, even with this method, about 3 to 5 cIr in front of the nozzle 2
The phosphor 3 does not adhere to the range L.

However, it is rather preferable that the phosphor 3 does not adhere to this range, and as shown in FIG.
The 5 cm portion of the phosphor film needs to be removed in order to improve the sealing properties of the glass, and even if there is an uncoated portion at the end on the nozzle insertion side, there is no practical problem. Also,
The total length is 1200m77! When coating a phosphor on the above bulbs, if you try to insert the nozzle from one end of the bulb to the other and paint, the overall length of the nozzle will become long, and when moving the nozzle, the center of the bulb will need to be aligned. This caused a problem in that the deviation from the center of the nozzle axis became large and the coating lacked uniformity.

Therefore, insert the nozzle from both ends of the bulb, and while also retracting the nozzle, eject the phosphor, so that each nozzle end is 2 to 3 inches from each end of the bulb. By simultaneously stopping the nozzle retraction for 0.5 to 1 second and spraying the phosphor when it reached the inside, an excellent coating with uniform thickness was obtained. In this case, the length of each nozzle is a percentage of the total valve length.
It can be shorter than the following, and it is also possible to insert both nozzles at the same time and retract them while ejecting the phosphor at the same time.You can also paint by retracting one one at a time, and in either case, the nozzle can be retracted for a short time at the end of the bulb. By stopping the process, a film of uniform thickness could be obtained. Example 1 A FL-20W type soda lime glass bulb with an inner diameter of 32 mm and a total length of 640 mm (7) was heated to approximately 350°C with a heating linear burner while rotating at a rotation speed of 100 times per minute, with the burner being negative and the nozzle being positive. A high voltage of 20k with the following polarity is applied.

Then, insert the nozzle with a length of 600 mm from one end to the other end into the rotating bulb, and spray the calcium halophosphate phosphor powder together with the compressed air flow at a speed of 300 dragons per second. The nozzle end is 20m77 from the nozzle insertion end of the valve!
When reaching the position, the nozzle was stopped for about 0.7 seconds and the phosphor was continuously sprayed to complete the coating. Excess powder was collected in a bag filter. Example 2 Inner diameter 32mm1
While rotating an FL-40W type soda lime glass bulb with a total length of 1280 mm at a rotation speed of 100 rotations per minute, it was heated to approximately 350 °C with a heating linear burner, and a polarity of 20 kV was applied, with the burner being negative and the nozzle being positive. Apply high voltage.

Then, insert nozzles each having a length of 400 mm into the rotating bulb from both ends, inject calcium halophosphate phosphor powder together with a stream of compressed air, and move each nozzle backward at a speed of 500 mm per second. ,
When each nozzle end came to a position 20 mu from the bulb end, the nozzle retraction was stopped for about 1 second, and the phosphor was continued to be ejected to complete the coating deposition. Excess powder was collected in a bag filter. The coating obtained in each example was uniform over the entire length of the bulb, and when measuring the transmittance of each part of the bulb and measuring the uniformity of the coating, it was found that the central part of the bulb was 30% (arbitrary unit). The thickness was extremely constant at 31 and 30 at both ends, the adhesion strength was strong, no baking was required as in the conventional method after the coating was applied, and the lamp luminous flux increased by about 4%.

Note that similar effects were obtained even when using other phosphors other than the calcium halophosphate phosphor, and the smaller the particle size of the phosphor, the better the uniformity and adhesion strength of the coating were.

Furthermore, excellent effects can also be obtained by mixing a small amount of dispersion or binding agent into the phosphor and coating it by the method of the present invention.

[Brief explanation of the drawing]

Figures 1 to 5 are cross-sectional views showing various states in which the phosphor sprayed from the nozzle adheres to the bulb, and Figure 6 shows the state with both ends of the phosphor film attached to the bulb removed. FIG. 1...Valve, 2...Nozzle, 3...
... phosphor, 4... phosphor membrane.

Claims (1)

[Claims] 1 Connect a high voltage generator so that the nozzle is positive and the valve heating burner is negative, insert the nozzle from one end or both ends of the heated bulb, and while retracting the nozzle at a constant speed, A method of injecting phosphor powder, wherein the nozzle is stopped for a short time from retracting just before the nozzle end exits the bulb, and then the phosphor powder is injected from the nozzle to inject the phosphor onto the inner surface of the bulb. An electrostatic coating method for a fluorescent lamp characterized by coating and depositing a luminescent powder.