JPS6366844A - Manufacture of incandescent bulb - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for improving the heat treatment conditions of a tungsten coil filament to improve the filament strength in the manufacturing process of an incandescent light bulb.

(Prior Art) In general, the general lighting bulb that is consumed in large quantities in Japan is the gas-filled double coil bulb (hereinafter referred to as CCTA bulb) specified in the Japanese Industrial Standard JIS C7501. This light bulb is a typical mass-produced product, and its production equipment consists of a series of interconnected production lines of high-speed machinery.

For this reason, all of the various parts used in light bulb manufacturing are standardized and designed to withstand high-speed processing.

(Problems to be Solved by the Invention) The tungsten coil filament, which is the core of the light bulb, is exposed to an arc breakage generation voltage (hereinafter referred to as S voltage) due to the initial voltage application obtained through the light bulb manufacturing process, particularly the heat treatment conditions after sealing. ) and mechanical strength such as impact, and these properties are often inversely related to each other. For example, if heat treatment is performed at a temperature far lower than the secondary recrystallization temperature in order to increase the mechanical strength of the filament, the S voltage of the light bulb will increase and it will become unusable.

Therefore, conventionally, in order to obtain the desired S voltage, the mechanical strength of the filament had to be sacrificed to some extent by heat-treating the filament at a temperature higher than the secondary recrystallization temperature. This has traditionally been considered as a gap, especially with a rating of 10
In CC light bulbs of 0 V and 40 W or less, the filament is wound with a particularly thin tungsten wire, so the mechanical strength of the filament is likely to be insufficient and the incidence of disconnection is high6.Therefore, the present invention aims to improve the mechanical strength of the filament It is an object of the present invention to provide a method for heat treating a coil filament so as to be compatible with the S voltage of a light bulb.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a step of sealing a tungsten coil filament and heat-treating the sealed filament by applying electricity to an incandescent light bulb filled with an inert gas such as argon.
By heating the filament so that it exceeds the yield point of the filament coil and the S voltage of the bulb is 150V or more, compared to the case where the filament is subjected to secondary recrystallization treatment, it is possible to prevent vibrations, shocks, etc. during normal handling. This ensures that wire breakage and wire breakage due to sparks hardly occur.

(Function) As a result of research, the present inventor discovered that it is possible to maintain the S voltage of the light bulb to the necessary limit without significantly reducing the mechanical strength of the filament in a limited narrow temperature range6. By limiting the number of wires as described above, it is possible to almost eliminate wire breaks caused by mechanical factors such as vibration and WI strike, as well as wire breaks caused by electrical factors such as arcing.

(Example) Hereinafter, the present invention will be explained in detail using a rated 100V 19WC; A light-diffusing film made by electrostatically coating the inner surface of this bulb ■ with fine silica powder, ■ is a stem that closes off the base end of the bulb (G), and (A) and (A) extend from this stem into the bulb ■. 1 pair of inner conductors, ■ indicates these inner conductors).

■Double coil type tungsten coil filament installed in the center of the valve ■.

■ is attached to the base of the valve ■ and the inner guide B (a), (a)
This is a cap that supplies power to the filament ■ through the filament ■. Then, inside the valve (g), 90% by volume of argon and 10% by volume of nitrogen were added.
A mixed inert gas consisting of % by volume is enclosed at normal pressure.

The above filament (■) is a tungsten wire with a wire diameter of 0.024 am wound twice to form a linear coil filament with a rating of 100V and 19W, and the inner core wire (@) and (■) are broken using the usual method. It is.

After the present CC incandescent lamp was assembled in the above-described configuration, power was supplied from the cap 0, and the filament 0 was energized at various voltages for about 4 seconds as described later, and heat treated by the Joule heat. In this heat treatment, the filament (■) was heated to a temperature that approximately corresponds to the applied voltage, and as a result, the tungsten constituting the filament (■) underwent a crystal change, resulting in changes in mechanical strength and S voltage as described below. .

Next, the correlation between the above-mentioned heat treatment conditions and the mechanical strength and S voltage of the obtained light bulb filament was investigated. The heat treatment conditions are expressed as a multiple of the voltage at which the filament melts by gradually increasing the applied voltage (hereinafter referred to as the melting voltage), the mechanical strength of the filament is expressed as the yield point of the secondary coil, and the S voltage is Various voltages of 50°C were applied to the cap for purpose, and the voltage was expressed as the voltage when the filament was fused by an inter-line arc at the first application.

The results are shown in FIG. In the figure, the horizontal axis shows the applied voltage as a multiple of the fusing voltage in units of V, and the vertical axis shows the breakdown point of the filament coil (in units of gf) and the S voltage (in units of V).
The unit is ) are arranged in parallel, the solid line indicates the yield point, and the broken line indicates the phase-to-phase of the S voltage. As is clear from Fig. 2, as the applied voltage increases, the heating temperature increases, and when the applied voltage exceeds 0.4 times the fusing voltage, the yield point decreases rapidly, becoming susceptible to impact, and secondary recrystallization. Show what you did. On the other hand, as the applied voltage increases, the S voltage also increases, indicating that the risk of filament melting due to arc decreases. The fact that the yield point curve intersects with the Sff and pressure curves in Figure 2 suggests that both shock-induced wire breakage and arc-induced wire breakage are reduced at an appropriate applied voltage. .

Therefore, the present inventors investigated how wire breakage due to impact and wire breakage due to arc change depending on the applied voltage. The investigation method was based on the standard in the industry, and the impact test was conducted by dropping the filament freely onto a wooden floor from a height of 70 AN to investigate the incidence of filament breakage.The arc test was conducted by dropping an AC voltage of 501 (z170V) 1 in between
The incidence of filament melting was investigated by applying the voltage only once. The results of this investigation are shown in Figure 3. In the figure, the horizontal axis shows the applied voltage as a multiple of the fusing voltage, and the disconnection occurrence rate is expressed as a percentage.
The solid line is the occurrence rate of wire breakage due to impact,
The broken line (...) shows the occurrence rate of wire breakage due to arc, and the chain line (-.-) shows the wire breakage occurrence rate that is the sum of both.

As is clear from FIG. 3, the total disconnection occurrence rate was lowest when the applied voltage was 0.4 times the fusing voltage.

In the above-described embodiment, the sealed filament was in the form of a linear double coil, but the present invention is not limited to this, and the filament may be in the form of a single coil, and the stretched shape may be annular or W-shaped. . However, if the shape and structure of the filament differs, the optimal value expressed as a multiple of the fusing voltage will differ even when the same heating state is obtained, so it is appropriate to express it in terms of the characteristics of the obtained filament. Experiments have shown that as long as the filament is coil-shaped, regardless of its shape and structure,
The yield point of the filament coil and the preferable range of the S voltage were as described above.

In the present invention, the gas sealed in the light bulb may contain 85 to 95% argon and the remainder may be nitrogen.

〔Effect of the invention〕

As described above, the method for manufacturing an incandescent light bulb of the present invention involves sealing a tungsten coil filament and sealing the filament by applying electricity to an incandescent light bulb filled with an inert gas containing argon as a main component. Since the heating was performed to a value that exceeds the yield point of the filament coil when subjected to the next recrystallization treatment and the S voltage of the bulb is 150V or more, the filament may break due to mechanical factors such as vibration or impact, and electrical problems such as arc discharge may occur. At the same time, the number of filament breakages due to various factors was reduced, and the total breakage rate was minimized.

[Brief Description of the Drawings] Figure 1 is a cross-sectional view of a light bulb obtained by an embodiment of the incandescent light bulb manufacturing method of the present invention, and Figure 2 is a graph showing the correlation between heat treatment conditions and filament characteristics. FIG. 3 is a graph similarly showing the correlation between heat treatment conditions and filament breakage incidence.

Claims (2)

[Claims] (1) In the process of heat-treating the filament by enclosing a tungsten coil filament and applying electricity to an incandescent lamp filled with an inert gas such as argon, the heat treatment of the filament is similar to that when the filament is subjected to secondary recrystallization treatment. A method for manufacturing an incandescent light bulb, which comprises heating the light bulb so that the S voltage of the light bulb exceeds the breakdown point of the filament coil and becomes 150V or more. (2) When the filament is in the form of a double coil, the heat treatment is performed by applying a voltage 0.35 to 0.45 times the fusing voltage of the filament.
2. Method for manufacturing an incandescent light bulb as described in Section 1.