JPS5826144B2 - Tube and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tube, particularly a tube used in a copying machine, and a method for manufacturing the same.

In order to make the temperature distribution of the fixing plate uniform, tubes used in copiers, especially as fuser heaters, do not have a uniform heat radiation distribution, that is, the heat radiation per unit length at the center of the tube is It is desirable to have a design in which the edge portion is larger than the amount.

Conventionally, three methods have been proposed as methods for manufacturing this tube.

The first method is to wind a single filament coil with a looser pitch near the center than at the ends, and by winding the pitch closer to the ends, the windings per unit length near the center of the tube are The amount of heat radiation per unit length of the end portion is greater than the amount of heat radiation per unit length of the end portion.

To manufacture this coil, it is necessary to create a variable pitch coil manufacturing machine, and this type of tube has not been put into practical use.

In the second method, the inner diameter of the coil near the center of one filament coil is wound thinner than the ends, and the inner diameter of the coil is wound thicker as it approaches the ends. The amount of heat radiated per unit length at the end is greater than the amount of heat radiated per unit length.

To manufacture this coil, it is necessary to use a core wire whose thickness changes continuously from thick to thin and from thin to thick. It is impossible to make such a core wire.

Therefore, tubes using this method have not been put into practical use either.

In the third method, a single filament coil is used, and the light-emitting part and the non-light-emitting part are connected alternately, and the ratio of the non-light-emitting part to the light-emitting part is set near the center of the tube compared to near the ends. This method reduces the amount of heat radiation per unit length near the center compared to the ends by increasing the amount of heat radiated from the center.

Currently, commercially available tubes use this method, but the presence of non-light-emitting parts has a major drawback in that the distribution of heat radiation emitted from the tube is uneven.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the present invention aims to provide a tube with uniform temperature change distribution on the irradiated surface and a method for manufacturing the same.

The present invention comprises a glass container having sealed parts at both ends, and a filament coil provided in the glass container, and the wire diameter of the wire at the end of the filament coil is the wire diameter of the wire at other parts. It features a smaller tube.

Furthermore, in manufacturing the above-mentioned tube, the present invention is characterized by a method of manufacturing the tube using a polishing method such as electrolytic polishing or chemical dissolution.

In other words, by polishing the end of the filament coil by electrolysis or chemical dissolution and reducing the diameter of the wire in that part, the resistance per unit length of the same part can be reduced to the unit length near the center of the filament coil. The filament coil is made larger than the original resistance value, so that when a predetermined current is passed through the filament coil, the amount of heat generated in the thinner portion is greater than in the other portions.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an apparatus for manufacturing a filament coil according to the present invention, in which a 10% aqueous solution 2 of sodium hydroxide is housed in a glass container 1, and a plate 3 made of tungsten is provided as an electrode in the glass container 1. .

The plate 3 is connected to a power source 5 by an electric wire 4.

The filament coil 6 is for 100V135W.

A length of 60 mm from one end of the coil having a total length of 300 mm is immersed in the solution 2, an electric wire 7 is connected to the other end, and a power source 5 is connected to this.

After electrolytically polishing one end of the filament coil 6 for 30 seconds at a voltage of 5 V, the other end was polished 60 mm from the end in the same manner.
The filament coil 6 was immersed in the solution 2 for 30 seconds at a voltage of 5 V and electrolytically polished.

In this way, a tube as shown in FIG. 2 was created using a filament coil whose wire diameter was reduced by 60 mm from the end.

In FIG. 2, a filament coil 6 is supported by a support 7 made of a tantalum plate, and molybdenum rods 8, 8' and molybdenum foil 9. Outer conductor 10 via γ
10' and sealed with sealing parts 12 and 12' to form a bulb.

Argon gas is sealed inside.

As a result of lighting up this tube and measuring the irradiance distribution at a distance of 20 mm from the tube axis, as shown in Figure 3, the irradiance near the ends of the tube is higher than the irradiance at the center of the tube. The peak illuminance was 20 to 30% higher.

As mentioned earlier, when a part of the filament coil is polished by electrolysis, the wire diameter of the tungsten wire in that part becomes thinner, and when current is passed through the filament coil, the resistance value per unit length increases. The temperature of the filament is higher in the part where the wire diameter is reduced than in other parts, and as a result, more radiation is emitted.

Furthermore, by changing the electrolytic polishing conditions, it is possible to change the ratio of radiation near the edges to radiation near the center.

In order to increase the amount of radiation from the center toward the ends, the level of the solution 2 can be raised or lowered, or the filament coil can be raised or lowered to change the extent to which the filament coil is immersed in the liquid.

In this way, the time for electrolytic polishing becomes longer as the filament coil goes from the center toward the ends, and the wire diameter of the filament coil becomes thinner as it goes from the center toward the ends. The amount of radiation increases from the center to the ends.

Although the electrolytic polishing method has been described above, the diameter of the tungsten wire can be similarly reduced by chemically dissolving the tungsten wire instead of electropolishing.

For example, hot nitric acid, hydrogen peroxide, a mixture of nitric acid and sulfuric acid,
The diameter of the tungsten wire of the filament coil can be reduced by dissolving it in a mixed solution of hydrofluoric acid and sulfuric acid.

In addition, although the example of the tube in which both ends of one filament coil are polished has been described above, in the case where multiple coils are connected to form one filament coil, the filament coils located at both ends are If the diameter of the wire at one end is smaller than the diameter at the other part,
As described above, the same effect as when both ends of one filament coil are polished from the beginning can be achieved.

By performing the same operation on one filament coil other than both ends, it is possible to adjust the heat distribution in the middle part.

As explained above, the present invention has advantages such that a desired filament coil can be obtained with a simple configuration, and the polishing operation of the filament coil is easy and does not require special consideration.

The tube of the present invention is suitable for use in a copying machine.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an apparatus for carrying out the method of the present invention, Fig. 2 is a front view of a tube that is an embodiment of the present invention, and Fig. 3 is a specific irradiance distribution diagram of the tube. . 1...Glass container, 2...Solution, 3.
...Plate, 4...Electric wire, 5...
Power supply, 6...Filament coil, 7...
...Electric wire, 12, 12'...Sealing part.

Claims (1)

[Scope of Claims] 1. A glass container having a sealed portion at both ends, and a filament coil provided in the glass container, wherein the wire diameter at the end of the filament coil is different from that of the wire in other parts. A tube characterized by having a wire diameter smaller than that of a tube. 2. A method for manufacturing a tube comprising a glass container having sealed parts at both ends and a filament coil provided in the glass container, the wire diameter of the wire at the end of the filament coil being adjusted by a polishing method. A method of manufacturing a tube comprising the step of making the diameter of the wire smaller than that of other parts. 3. The method for manufacturing a tube according to claim 2, wherein the polishing method is an electrolytic polishing method. 4. The method for manufacturing a tube according to claim 2, wherein the polishing method is a chemical dissolution method.