JPS6115739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a phosphor layer on the inner surface of a bulb of a fluorescent lamp, mercury lamp, or the like.

Conventionally, in order to form a phosphor layer on the inner surface of a bulb such as a fluorescent lamp, a phosphor coating liquid is prepared by dispersing phosphor powder in a lacquer containing an organic binder dissolved in a solvent, and this is applied inside a glass tube. A method is used in which a phosphor coating film is formed by applying it to a surface and drying, and then heating and baking the glass tube to burn off the organic binder remaining in the coating film. This method has been used for a long time because it is relatively easy to form a phosphor layer with a uniform thickness, but because it consumes a large amount of thermal energy in the drying and firing processes, the recent rise in energy costs has caused this method to decline. points have become a major problem.

To solve this problem, there are various methods of forming a phosphor layer using the so-called electrostatic powder coating method, in which powder particles are charged and applied directly to a grounded object, that is, the inner surface of the bulb. It is being considered.

For example, as shown in FIG. 1, an injector 2 is installed at the bottom of a phosphor storage container 1 in which a phosphor 1a is housed, and high-pressure air is fed into the injector 2 from an air inlet 3 to remove the phosphor 1a. is inhaled, and the fluorescent material 1a is introduced together with this high-pressure air through the powder transfer tube 4 to the injection nozzle 5 provided at the tip of the transfer tube 4. Also, a high voltage charging needle is built into the injection nozzle 5 to charge the passing powder particles, that is, the phosphor 1a. It is conceivable to spray it onto the inner surface of the valve 7 and apply it using the force of static electricity.

However, the apparatus shown in FIG. 1, which is widely used for general painting, is simply used for forming a phosphor layer on tubes, and the following problems have occurred. This is due to the properties of the powder used in Figure 1, that is, the powder used for painting is generally made of plastic with a specific gravity of about 1.0 to 1.5, and the particle shape is adjusted to improve fluidity. However, the phosphor used in tubes generally has a relatively large specific gravity of 3.0 to 5.0, and has poor fluidity and tends to aggregate, so the suction by air injector 2 is constant. Without this, the concentration of powder jetted from the nozzle 5 tends to fluctuate. Next, in order to mass-produce the coating on the inner surface of the valve 7 of the tube, the injection from the nozzle 5 must be performed intermittently, but if the powder feed air is made intermittent, the air will be stopped. The phosphor is deposited in the powder transfer tube 4 when the powder is transferred, and the deposited phosphor is suddenly blown out when the air is supplied the next time. Not constant. As shown in Figure 2, this shows that the calcium halophosphate phosphor 1
Attach a to the inner surface of the 20W fluorescent lamp bulb 7, 2 per bulb.
This is also clear from the results of measuring the concentration of the powder sprayed from the tip of the nozzle 5 when the powder is sprayed at a rate of 1 second and the spray is stopped for 1 second (a new valve 7 is supplied during this time). Note that the powder concentration was expressed as a relative value because it was measured by the change in light transmittance. In other words, as is clear from FIG. 2, the concentration of the injected powder differs for each injection, and the fluctuation is particularly large after the second injection.
The peaks that occur from the second time onwards are the result of the phosphor 1a deposited in the powder transfer tube 4 when the air flow is stopped being solidified and ejected when the next injection is performed. As a result, the thickness of the phosphor layer applied to each bulb 7 varies, making it difficult to form a layer with a uniform thickness on the inner surface of the glass bulb 7, and the thickness of the phosphor layer varies. Fluorescent lamps, mercury lamps, and the like, which have a sensitive effect on luminous efficiency, inevitably suffer from large fluctuations in their characteristics.

This invention was made in view of the above points, and involves weighing a certain amount of phosphor using a scale, and supplying the weighed phosphor to a plate-shaped portion of a powder diffusion plate that is rotated at high speed. This diffused phosphor is guided along with air to a nozzle and sprayed from the nozzle, making it possible to easily form a phosphor layer of uniform thickness on the inner surface of a glass bulb such as a fluorescent lamp. The purpose is to

An embodiment of the present invention will be described below based on FIG. 3. In the figure, 6 is a fluorescent material storage container 1
A weighing device consisting of a feeder for weighing a certain amount of phosphor 1a from a feeder, with an inlet 8 communicating with a phosphor outlet provided at the bottom of the phosphor storage container 1 at one end, and an inlet 8 provided at the other end. It consists of a cylindrical body 7 having a phosphor discharge port 9 and a core rod 10 in which a helical groove is formed in the interior of the cylindrical body 7 to a position corresponding to the inlet 8 and the discharge port 9. The rod 10 is intermittently rotated, and the phosphor 1a supplied from the inlet 8 is attached to the core rod 1.
0 and discharges a certain amount of the phosphor 1a from the discharge port 9. Reference numeral 12 denotes a phosphor supply pipe 13 that communicates with the outlet 9 of the weighing device 6, an air inlet 3 that communicates with an air inlet (not shown), and a phosphor outlet that is connected to the nozzle 5. 1
4 and in which a phosphor dispersion chamber 15 is formed;
Reference numeral 16 denotes a powder dispersion plate having a plate-shaped portion 17 which is disposed inside the main body in correspondence with the tip of the fluorescent material supply tube 13 and rotated at high speed, and constitutes the powder disperser 11 together with the main body 12. This is what we are doing.

In the phosphor powder coating apparatus configured in this way, in order to coat the phosphor 1a on the inner surface of the bulb 7 of the fluorescent lamp, air is continuously supplied from the air feeder through the air inlet 3. When the valve 7, which is intermittently transferred to the position of the nozzle 5, comes to a position facing the powder injection nozzle 5, the weigher 6
The core rod 10 rotates by a predetermined amount, and the discharge port 9 of the weighing device 6
A predetermined amount of the fluorescent material 1a is supplied onto the dish-shaped portion 17 of the powder dispersing plate 16 of the powder dispersing device 11. The supplied phosphor 1a falls onto the dish-shaped portion 17 which is rotating at high speed, and at the same time is instantly diffused and dispersed throughout the dispersion chamber 15 due to the action of the centripetal force and the dish-shaped shape. The dispersed phosphor 1a is ejected from the powder discharge port 14 to the injection nozzle 5 by an air flow.
At this point, it is charged, blown into the bulb 7, and coated on the inner surface. Then, when the next valve 7 to be coated is sent to a position opposite the nozzle 5, the weighing device 6 is activated and the above operation is repeated.

When the phosphor 1a is coated on the inner surface of the bulb 7 in this way, the air for powder transfer and injection is kept flowing at all times, and the phosphor 1a, which is the powder to be coated, is weighed in a fixed amount using a weighing device 6. Weighed and supplied, spreader plate 16
Since the powder is forcibly dispersed, the concentration of the powder injected from the injection nozzle 5 is constant every time, and the thickness of the formed phosphor layer has extremely little variation. This point is also supported by the following experiment. In other words, Fig. 4 shows the measurement of the concentration of the powder sprayed from the nozzle 5 when the calcium halophosphate phosphor is applied to the inner surface of the bulb 7 for a 20W fluorescent lamp for an index of 3 seconds using the apparatus shown in Fig. 3. This is the result. As is clear from FIG. 4, the spraying condition is extremely stable compared to the results obtained when the conventional powder coating apparatus shown in FIG. 2 is used.

As described above, the apparatus of the present invention is effective in uniformly and uniformly coating the inner surface of a tube bulb with fluorescent powder used in tubes, which has relatively poor dispersibility.

As described above, this invention uses electrostatic powder coating to apply a fluorescent material to the inner surface of a bulb of a fluorescent lamp, etc., instead of the conventional method of applying a fluorescent material as a coating liquid. On the other hand, in order to save resources and eliminate pollution, it has a weigher for weighing a fixed amount of phosphor and a powder diffusion plate having a plate-shaped part that rotates at high speed. Since a powder disperser is provided in which powder is supplied to this dish-shaped portion, there is an effect that a constant and uniform phosphor layer can be formed on the inner surface of a bulb of a fluorescent lamp or the like.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional electrostatic powder coating installation, Fig. 2 is a diagram showing the powder spray concentration of the device shown in Fig. 1, and Fig. 3 is a schematic diagram showing an embodiment of the present invention. ,
FIG. 4 is a diagram showing the powder injection concentration of the apparatus shown in FIG. 3. In the figure, 1 is a phosphor storage container, 1a is a phosphor, 3 is an air inlet, 5 is a nozzle, 6 is a scale,
7 is a valve, 11 is a powder disperser, 12 is a main body, 1
6 is a powder diffusion plate, and 17 is a dish-shaped portion.

Claims (1)

[Claims] 1. A phosphor storage container that stores the phosphor, a weighing device that takes out and supplies a certain amount of the phosphor from the phosphor storage container, and a powder dispersion device that mixes the phosphor supplied from the weighing device into an air flow and discharges it. The powder disperser has a main body provided with an air inlet and a phosphor outlet. a powder diffusion plate that is rotatably housed in the main body and has a dish-shaped portion that receives a fixed amount of phosphor from the weighing device; and a powder diffusion plate that is connected to the air inlet and that is 1. A phosphor powder coating apparatus comprising: an air feeder that mixes the phosphor diffused in the air flow formed in the main body and sends the phosphor to the phosphor discharge port.