JPH08236023A - Bead fixing method to electrode lead - Google Patents

Abstract

PURPOSE: To reduce a cost by decreasing a man-hour by forming, without providing an independent process, a preliminary oxide film formed previously in a lead wire for enhancing adhesion of glass, in the case where burning and fixing the bead glass for sealing to an electrode lead. CONSTITUTION: Simultaneously with resistance welding a lead wire 2b to an electrode 2a, this generated heat is utilized to perform preliminary oxidation of the lead wire 2a, and bead glass 6 is fixed while blowing reducing gas. In this way, an unnecessary oxide film not coated with the bead glass is reduced to be removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bead fixing method for electrode leads used in cold cathode fluorescent lamps and the like.

[0002]

2. Description of the Related Art A cold cathode fluorescent lamp used for a liquid crystal backlight is manufactured, for example, as shown in FIG. 2, by sealing electrode leads 2 at both ends of a glass bulb 1 having a small diameter. The electrode lead 2 is, for example, a rod-shaped nickel electrode 2a to which a lead wire 2b made of Kovar is resistance-welded. For this sealing work, as shown in FIG. 3, an electrode lead 2 in which a bead glass 3 is baked and fixed in advance to a portion to be sealed of the lead wire 2b is prepared, and this is inserted into both ends of the glass bulb, and the glass bulb 1 is attached. It is done by heating from the outside. The bead glass 3 is made of, for example, borosilicate glass of the same material as the glass bulb 1,
The gap with the glass bulb 1 is narrowed to facilitate and secure the sealing, and the coefficient of thermal expansion is matched with that of Kovar, which is the material of the lead wire 2b, to prevent cracks during heating and cooling.

The bead glass 3 is baked in a state in which the surface of the lead wire 2b is roughened by etching and the surface is further oxidized. As a result, the lead glass of the bead glass is made to fit well and the airtightness and the bonding strength are improved.

This oxidation has hitherto been carried out in the following electrode lead manufacturing process.

First, as shown in FIG. 4 (a), a rod-shaped nickel electrode 2a and a Kovar lead wire 2b whose surface is roughened by etching are butted against each other and resistance-welded. At this time, if the nickel electrode 2a is oxidized, the function as an electrode is lost, so this resistance welding is performed with alcohol flowing to protect the surface, and the whole is kept in a non-oxidized state.

Next, as shown in FIG. 4B, the lead wire 2
The bead glass fixing portion of b is partially heated by the gas burner 4 to perform surface oxidation.

Then, as shown in FIG. 4 (c), a bead glass 6 is fitted to the portion of the lead wire where the oxide film 5 is formed,
While blowing the reducing gas (not shown), the bead glass 6 is heated and melted by the gas burner 7 and baked on the lead wire to obtain the state of FIG.

[0008]

The above-mentioned conventional method requires an independent process for pre-oxidation by the gas burner. However, since the electrode lead is a mass-produced product and the total number of steps is small, this step occupies a large proportion of the manufacturing cost. In addition, this heating method has a problem that it is difficult to obtain a stable oxide film because it is difficult to apply a burner flame uniformly. Further, it is necessary to dispose this gas burner in the manufacturing line, but this requires a plurality of heads in order to obtain the required processing capacity, and it is necessary to consider the layout of the equipment. Further, there is a problem that management cost is required for adjusting the burner position and the flame.

In order to obtain a stable oxide film, it is sufficient to slowly heat it in an oven.
It takes 0 minutes and the whole structure including the nickel electrode is uniformly oxidized, so that it cannot be adopted. In addition, such a batch process cannot be incorporated in a production line.

Therefore, the present invention provides a method in which an oxide film can be attached only to a required portion without an oxidation step using a gas burner, thereby reducing costs by reducing the number of steps, and adjusting the gas burner in use. The purpose is to eliminate the problem.

[0011]

According to the method for fixing beads to an electrode lead provided by the present invention, an electrode and a lead wire are resistance-welded in a state where surface oxidation occurs due to heat during welding, and a lead wire is to be sealed. The position is covered with a bead glass, and the bead glass is heated by a gas burner while blowing a reducing gas.

[0012]

According to the above-mentioned method, at the same time as the resistance welding of the electrode 2a and the lead wire 2b, the portion of the lead wire 2 to be fixed to the bead glass can be pre-oxidized. Therefore, the step of pre-oxidation, which has been conventionally required, becomes unnecessary, and the manufacturing cost can be reduced by reducing the number of steps.

[0013]

The present invention will be described according to one embodiment.

First, as shown in FIG. 1 (a), a nickel electrode 2a and a Kovar lead wire 2b are coaxially brought into contact with each other by a predetermined chucking device to perform resistance welding. This is performed in the air, and alcohol or the like for surface protection is not used. Electrode lead 2 due to heat generated by resistance welding
Are heated and react with oxygen in the atmosphere. As a result, at the same time as resistance welding, pre-oxidation for enhancing the adhesion of the bead glass is performed. In order to ensure this pre-oxidation, the oxygen content in the welding atmosphere can be increased.

Next, as shown in FIG. 1 (b), the bead glass 6 is fitted at the planned sealing position. In this state, while the reducing gas 8 such as hydrogen is sprayed, the bead glass 6 is heated and melted by the gas burner 7 to fix the bead glass. As a result, the bead glass is melted and fixed as the round bead glass 3 as shown in FIG.

At the time of this fixing, the reducing gas 8 acts on the electrode lead 2 in a heated state, so that the surface oxidation of the electrode 2a and the surface oxidation of the portion of the lead wire 2b not covered with the bead glass 6 are prevented. be able to. As a result, the function of the electrode 2a is ensured, and the connecting function of the lead wire 2b by the connector or soldering is guaranteed. The oxide film in the portion of the lead wire 2b covered with the bead glass 6 is
Since this gap is small and is quickly covered with the bead glass melted by the heating by the gas burner, it is left almost as it is. The preliminary oxide film can enhance the adhesion and the bond strength with the bead glass.

[0017]

According to the present invention, the electrode 2a and the lead wire 2 are
Simultaneously with the resistance welding of b, the generated heat is used to pre-oxidize the lead wire 2a, and the bead glass 6 is fixed while spraying a reducing gas, thereby unnecessary oxidation of the portion not covered with the bead glass. Since it is possible to prevent the partial pre-oxidation without providing an independent process, it is possible to reduce the manufacturing cost by reducing the number of steps.

[Brief description of drawings]

1A to 1C show, in order, the bead fixing process of an electrode lead according to the present invention, in which (a) is a resistance welding process performed while pre-oxidizing, and (b) is a bead performed while reducing and removing an unnecessary oxide film. It is a figure which shows the fixing process of glass.

FIG. 2 shows a cross-sectional view of a cold cathode fluorescent lamp having a small diameter, which is an example of an object to which the electrode lead of the present invention is attached.

FIG. 3 is a cross-sectional view of an electrode lead to which bead glass is fixed and before sealing.

4A to 4C sequentially show a conventional bead winding process of an electrode lead, in which (a) is a resistance welding process performed while being protected by alcohol, (b) is a pre-oxidation process of a lead wire by a gas burner, and (c). FIG. 4 is a diagram showing a bead glass fixing step.

[Explanation of symbols]

 1 Glass bulb in which electrode lead is sealed 2 Electrode lead 2a Electrode 2b Lead wire 2b Lead wire 3 Adhering bead glass 6 Bead glass covered on lead wire 7 Gas burner for adhering and adhering bead glass 8 Reducing gas

Claims (1)

[Claims] 1. A method for fixing bead glass in a pre-oxidized state to a sealing portion of an electrode lead to be sealed in a glass bulb, wherein the surface of the electrode and the lead wire is oxidized by heat during welding. A method for fixing a bead to an electrode lead, which comprises performing resistance welding in a state where it occurs, covering a lead wire at a predetermined sealing position with bead glass, and heating the bead glass with a gas burner while blowing a reducing gas.