JPS6215992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a conductive coating for a trigger provided on the outer surface of a bulb of a flash discharge tube.

The flash discharge tubes used in electronic flash devices useful for photography come in straight, U-shaped, and spiral shapes.The surface of each bulb is covered with a transparent conductive coating made of metal oxide for triggering. It is well known that this type of discharge tube is used, and FIG. 1 shows the structure of the straight discharge tube.

Its configuration consists of 3 valves with rare gas sealed inside.
The positive and negative main electrodes 1 and 2 are sealed at both ends of the bulb 3, and a trigger transparent conductive coating 4 is applied to the outer surface of the bulb 3, and a trigger circuit (not shown) is applied to the trigger transparent conductive coating 4. A trigger lead wire 5 is provided for applying a trigger pulse.

This transparent conductive coating for triggering (hereinafter simply referred to as a conductive coating) must not be applied to the areas shown by the arrows on the main electrodes 1 and 2 in order to ensure discharge excitation.

For this purpose, as shown in FIG. 2, the above-mentioned portion on which the conductive coating is not applied is immersed in a suspension 7 containing, for example, fine powder of metal oxide and water or an organic solvent, which is placed in a container 8. The coating 6 is coated to form a coating 6, and after drying the coating 6, it is placed in a high-temperature bath at around 600°C, and then a metal salt solution made of, for example, stannic chloride and an organic solvent is atomized using a spray gun or the like. The conductive coating 4 is formed at the location shown in FIG. 1 by spraying it onto the bulb surface, leaving the coating 6 intact, and finally the coating 6 is washed off.

Although the conductive film is formed as described above, this method has the following drawbacks.

First, it takes time and effort to apply the coating 6 by immersing the portion to which no conductive coating is to be applied in the suspension 7 and finally washing off the coating.

Second, since the coating 6 is heated to a high temperature of around 600 degrees Celsius, it becomes baked onto the bulb 3 to some extent and requires the use of something like a brush to completely wash it off, which not only takes time; This will damage the valve surface.

Third, when spraying a mist of a solution containing metal chloride as the main component to form a conductive film on the bulb surface, a portion of the coating 6 may fly off and adhere to the bulb surface. A conductive film is not formed on the attached portion, and on the contrary, a conductive film is formed on the part where the coating 6 has been scattered, which may cause a discharge failure.

Therefore, the present invention provides a method for forming a conductive coating on a discharge tube that completely eliminates these drawbacks.
Embodiments will be explained below with reference to drawings showing embodiments.

FIGS. 3 and 4 show the process of forming a conductive film by the method for forming a conductive film of the present invention.

In FIG. 3, reference numeral 9 denotes a holding stand for holding a valve 3 which seals the main electrodes 1 and 2 and seals a rare gas inside. A support part 10 having a hole 12 and supporting the valve is provided.

A hole 11 into which the protruding portion of the main electrode 1 or 2 from the bulb 3 is inserted is provided at the bottom of the hole 12 of the support portion 10, and the height h of the hole 12 is set to a height h of the bulb 3.
The length is approximately equal to the length of the conductive film-free portion.

Reference numeral 13 denotes a cap that covers the conductive film-free portion of the main electrode 1 or 2 of the bulb 3, and is provided with a fitting hole 14 having a shape substantially equal to the shape of the main electrode and the conductive film-free portion of the bulb 3.

Note that the support portion 10, the holding table 9, and the cap 13 are made of a material that can withstand high temperatures, such as a metal material.

The main electrode 1 or 2 side of the bulb 3 is fitted into the supporting part 10 having such a structure, and the cap 13 is covered with the main electrode 1 or 2 opposite to the fitted side.

The state in which the valve 3 is held on the holding base is shown in cross-sectional view as shown in FIG.
This holding table was heated to 600℃ in order to form a conductive film on the
After being heated in the front and rear high-temperature baths, a solution of metal chloride dissolved in a solvent is atomized by a spray gun 15 and irradiated toward the bulb 3.

This solution is irradiated with a spray gun in the form of a mist and is sprayed onto the bulb 3, and since the mist of this metal salt solution is trapped in the high temperature bath, a conductive film is formed over the entire surface of the bulb 3. If the valve 9 is rotated only during the irradiation of the solution, a uniform conductive film will be formed on the surface of the bulb 3.

As described above, as shown in FIG.
0, the conductive film 4 is formed only at predetermined locations except for the areas where the conductive film is not formed due to the cap 13.

In addition, the hole 12 of the support part 10 and the cap 13
It is preferable that the shape of the hole 14 is in close contact with the bulb 3 as much as possible, but in many cases, even if there is a slight gap, a conductive film is not formed in the part that fits into the holes 12 and 13. Confirmed by testing.

FIG. 6 is a cross-sectional view showing the case where a conductive coating is formed on a U-shaped discharge tube. A pair of support parts 1 into which the conductive film-free part on the side is fitted
0' and 10'' are provided on the holding table 9', and a conductive film can be formed by holding the bulb 3' in such a state, heating it at a high temperature, and then irradiating the solution with a spray gun as described above.

As described above, according to the present invention, it is possible to form a conductive film without applying a powder suspension of metal oxide to cover the area where the conductive film is not formed, as in the conventional method, which improves workability. There is no damage to the conductive film, loss of the conductive film, or formation of the conductive film in areas where the conductive film is not formed.

Although the description has been made with reference to only one bulb on which a conductive film is formed, the supporting parts 10, 10',
It is of course possible to form conductive coatings on a large number of bulbs at the same time by providing a large number of 10", 20...n bulbs on the holding stand.

[Brief explanation of the drawing]

Figure 1 is a front view of the structure of a straight discharge tube, Figure 2
The figure is a sectional view showing a conventional method of forming a coating on a portion where no conductive coating is formed, and Figures 3 to 5 are diagrams showing a process in which the method of forming a conductive coating of the present invention is applied to a straight discharge tube. , and FIG. 6 are diagrams in which the method for forming a conductive film of the present invention is applied to a U-shaped discharge tube. 1, 1', 2, 2'... Main electrode, 3, 3'... Bulb, 4... Conductive coating, 5... Trigger lead wire, 9, 9'... Holding stand, 10, 10', 10 ″…
...Support part, 13...Cap, 15...Spray gun.

Claims (1)

[Scope of Claims] 1. A method for forming a conductive coating for a trigger on a predetermined portion of each of a plurality of bulbs of a discharge tube in which two main electrodes are sealed and a rare gas is sealed inside, Each discharge tube is a straight tube type,
Fitting the non-formed parts of the bulb where the conductive film is not formed near one of the two main electrodes into a plurality of support parts made of a heat-resistant material and provided on a holding base, respectively; The non-formed portion of the bulb where the other main electrode is sealed and the conductive coating is not formed is covered with a plurality of caps made of a heat-resistant material, the bulb is heated, and the conductive coating is formed in a predetermined area of the bulb. After irradiating the bulb with a solution to form the conductive film on the bulb, the cap is removed and the bulb is taken out from the support section and a trigger is applied to a predetermined portion of the plurality of bulbs of the discharge tube. A method for forming a conductive film for a discharge tube trigger. 2. In a method of forming a conductive coating for triggering on a predetermined portion of a plurality of bulbs of a discharge tube in which two main electrodes are sealed and a rare gas is sealed inside, each of the plurality of discharge tubes is connected to the bulb. is a discharge tube formed into a U-shape or spiral shape, and the two main electrodes are provided in the same direction, and the non-formed portion of the bulb where the conductive film is not formed near the two main electrodes is made of a heat-resistant material. The bulbs of the plurality of discharge tubes are heated, and the conductive coating is applied to the bulbs of the plurality of discharge tubes. After forming the conductive film on the plurality of bulbs by irradiating the bulbs of the plurality of discharge tubes with a solution to be formed on a predetermined portion, the bulbs of the plurality of discharge tubes are taken out from the plurality of supporting parts. A method for forming a conductive film for a discharge tube trigger.