TWI750070B - Leads and bulbs for vehicles - Google Patents

Abstract

The present invention provides a lead wire having a simple structure and capable of suppressing the opening of the bent portion of the lead wire, a method for manufacturing the lead wire, and a vehicle bulb. The lead wire of the embodiment includes: a core material, which has a linear shape, and includes iron and nickel; and a coating layer, which includes nickel, and covers the surface of the core material. The thickness of the coating layer is 1.0 μm or more and 6.0 μm or less.

Description

Leads and bulbs for vehicles

The invention relates to a lead wire, a method for manufacturing the lead wire, and a bulb for a vehicle.

The following vehicle bulbs already exist, which include: a bulb containing glass and provided with a sealing part at the end; a pair of lead wires, one end of which is arranged inside the glass bulb and the other end exposed from the sealing part; and a filament ( filament), inside the glass bulb, held at the ends of a pair of leads. The end of the lead wire is bent to hold the leg of the filament in a manner of clamping the leg of the filament. Here, the end of the glass bulb containing glass is heated, and the end of the heated glass bulb is pressed together with a pair of leads, thereby forming a sealed portion. Therefore, the pair of leads are formed of a material having a thermal expansion coefficient close to that of glass. In general, the lead includes: a core material, including Fe-Ni alloy; a layer including copper, covering the core material; and a layer including nickel, covering the layer including copper. The thermal expansion coefficient of the lead wire including the core material containing the Fe-Ni alloy is close to that of glass. Therefore, it is possible to suppress a situation in which when a pair of lead wires are sealed to the ends of the glass bulb, the lead wires and the sealing portion are not completely adhered to each other and a leak occurs.

However, the thermal expansion coefficient of the core material containing Fe-Ni alloy, the thermal expansion coefficient of the copper-containing layer, and the thermal expansion coefficient of the nickel-containing layer are different. Therefore, when the vehicle bulb is turned on, the bent portion of the lead wire may open due to the heat generated by the filament, causing the leg of the filament to separate from the lead, or the electrical connection between the lead and the leg of the filament May be hindered.

Therefore, a wire has been proposed in which the wire including the core material, the layer including copper, and the layer including nickel, and the wire including nickel are bonded. As long as the wire material including the core material, the layer containing copper, and the layer containing nickel is sealed to the sealing portion, the generation of cracks can be suppressed. In addition, as long as the end of the wire material containing nickel is bent to sandwich the leg of the filament, it is possible to suppress the bending of the bent portion from being opened due to the heat generated by the filament. However, in this case, the structure of the lead becomes complicated, leading to an increase in manufacturing cost. Therefore, it is desired to develop a technology that has a simple structure and can suppress the opening of the bent portion of the lead. [Prior Art Literature]

[Patent Literature] [Patent Document 1] Japanese Patent Laid-Open No. 9-45291

[The problem to be solved by the invention] The problem to be solved by the present invention is to provide a lead wire that has a simple structure and can suppress the opening of the bent portion of the lead wire, a method of manufacturing the lead wire, and a vehicle light bulb. [Technical means to solve the problem]

The lead wire of the embodiment includes a core material, which is linear and includes iron and nickel, and a coating layer, which includes nickel, and covers the surface of the core material. The thickness of the coating layer is 1.0 μm or more and 6.0 μm or less.

[Effects of the invention] According to the embodiment of the present invention, it is possible to provide a lead wire, a method for manufacturing the lead wire, and a vehicle light bulb that have a simple structure and can suppress the opening of the bent portion of the lead wire.

Hereinafter, embodiments will be illustrated with reference to the drawings. In addition, in each drawing, the same reference numerals are attached to the same constituent elements, and detailed descriptions are appropriately omitted. FIG. 1 is a schematic partial cross-sectional view for illustrating a vehicle light bulb according to this embodiment. Fig. 2 is a schematic diagram for illustrating a bent portion of a lead. The vehicle light bulb 1 of the present embodiment can be used for brake lights, direction indicators, tail lights, etc., installed in vehicles such as two-wheeled vehicles or four-wheeled vehicles (automobiles). In addition, the vehicle light bulb 1 illustrated in FIG. 1 is a wedge base light bulb that does not include a lamp socket. However, the use or form of the vehicle bulb 1 is not limited to the use or form already exemplified. The vehicle light bulb 1 of the present embodiment can be applied to a vehicle light bulb including a pair of lead wires 6 holding a filament 4 inside a glass bulb 2.

As shown in FIG. 1, the bulb 1 for a vehicle is provided with the glass bulb 2, the sealing part 3, the filament 4, the fixing member 5, and the lead wire 6. As shown in FIG. The glass bulb 2 becomes a cylindrical body with one end in a hemispherical shape. The shape of the glass bulb 2 is not limited to the exemplified shape. For example, it can be A-shaped, G-shaped, PS-shaped, R-shaped, T-shaped, or a composite shape of these shapes, or include a plate-shaped body or a dish-shaped body, etc. The flat shape and so on. A sealing part 3 is provided at the other end of the glass bulb 2. In addition, the glass bulb 2 is formed of a light-transmitting material. Therefore, the glass bulb 2 becomes a light-transmitting airtight container.

The glass bulb 2 can be formed of glass such as soda lime glass, alkali glass, and alkaline earth silicate glass (also referred to as lead-free glass, etc.). The physical properties of glass are, for example, a softening point of 665°C, an annealing point of 480°C, a strain point of 440°C, a thermal conductivity (100°C) of 1.1 (W/(m·K)), and a coefficient of thermal expansion (30°C to 380°C) ) Is 5×10 ^-6 /℃ or higher (for example, 9.45×10 ^-6 /℃). In this case, the glass bulb 2 only needs to have translucency. For example, the glass bulb 2 may be colorless and transparent, or may be colored. In addition, a coating film such as a colored film, a reflective film, a diffuser film, or a phosphor film, or unevenness may be provided on the surface or the inner surface of the glass bulb 2. The glass bulb 2 may also be formed of a material containing a scattering material, a phosphor, or the like.

The pressure inside the airtight container, that is, the glass bulb 2, is lower than the atmospheric pressure, or an inert gas is enclosed. The sealed inert gas can be, for example, xenon (Xe), krypton (Kr), argon (Ar), or a mixed gas of these gases. In addition, the enclosed inert gas can also contain nitrogen (N ₂ ) and the like. When the inert gas is enclosed, the pressure inside the glass bulb 2 can be about 0.5 MPa to 3.0 MPa. As long as the inert gas is enclosed, evaporation of the filament 4 can be suppressed, and the life of the vehicle bulb 1 can be prolonged.

The sealing part 3 has a rectangular parallelepiped shape. As described above, the sealing part 3 seals one end of the glass bulb 2. For example, by heating the end of the glass bulb 2 and pressing the heated end of the glass bulb 2 together with the pair of lead wires 6, the sealing portion 3 can be formed. In this case, the sealing part 3 is also formed of glass. An exhaust pipe 3 a is provided in the sealing part 3. The exhaust pipe 3 a penetrates the inside of the sealing part 3 and communicates with the inside of the glass bulb 2. The exhaust pipe 3 a is used when exhausting the inside of the glass bulb 2 or sealing an inert gas inside the glass bulb 2. The end of the exhaust pipe 3a on the outside air side is sealed. In addition, it is possible to provide a convex hook portion or the like on the sealing portion 3, and the convex hook portion or the like can be used when the vehicle bulb 1 is held in a lamp installed in the vehicle.

The filament 4 includes a coil 4a and legs 4b respectively provided at both ends of the coil 4a. The coil 4a is formed by winding a wire. The leg 4b linearly extends from the end of the coil 4a. The coil 4a and the leg 4b are formed integrally. The filament 4 (coil 4a, leg 4b) can be formed of, for example, a wire material containing tungsten (W) as a main component.

The fixing member 5 is provided inside the glass bulb 2. The fixing member 5 holds a pair of lead wires 6. The fixing member 5 can be formed of glass, for example. For example, by pressing a member including heated glass together with a pair of leads 6, the fixing member 5 can be formed. In this case, the glass bulb 2, the sealing portion 3, and the fixing member 5 can also be formed of the same material.

The lead 6 has a linear shape. The cross-sectional size (diameter size) of the lead 6 can be set to 0.2 mm or more and 0.76 mm or less, for example. As shown in FIG. 2, one end of the lead wire 6 is bent to hold the leg 4b of the filament 4 in a manner of clamping the leg 4b of the filament 4. The other end of the lead 6 is exposed from the sealing part 3. The portion of the lead 6 exposed from the sealing portion 3 serves as a terminal for connection with an external power source or the like.

Here, if the difference between the thermal expansion coefficient of the material of the lead 6 and the thermal expansion coefficient of the glass, which is the material of the sealing portion 3, becomes large, the lead 6 and the sealing portion 3 may not completely adhere to each other and cracks may occur. Therefore, the lead 6 is formed of a material having a thermal expansion coefficient close to that of glass.

Fig. 3 is a schematic diagram illustrating a cross-section of a lead of a comparative example. As shown in FIG. 3, the lead 16 includes a core material 16a, a cladding layer 16b, and a cladding layer 16c. The core material 16a has a linear shape. The cross-sectional shape of the core material 16a is, for example, a circle. The core material 16a is formed of a material having a thermal expansion coefficient close to that of glass. The core material 16a can be formed of, for example, an alloy containing iron (Fe) and nickel (Ni).

The clad layer 16b covers the surface of the core material 16a. The clad layer 16b contains copper (Cu), for example. The coating layer 16c covers the surface of the coating layer 16b. The coating layer 16b contains nickel, for example. As long as the coating layer 16c containing nickel is provided, it is possible to suppress oxidation of the coating layer 16b containing copper when the lead 16 is sealed to the sealing portion 3. In addition, when the lead 16 is sealed to the sealing portion 3, the surface of the coating layer 16c is oxidized to generate nickel oxide, and the nickel oxide diffuses into the glass. Therefore, the lead 16 and the sealing portion 3 can be brought into close contact.

Therefore, as long as the lead wire 16 is used, it is possible to prevent the lead wire 16 and the sealing portion 3 from being incompletely adhered to each other to cause cracks. However, since the materials of the core material 16a, the clad layer 16b, and the clad layer 16c are different, the thermal expansion coefficients of the core material 16a, the clad layer 16b, and the clad layer 16c are different. As described above, one end of the lead wire 16 is bent to hold the leg 4b of the filament 4 in a manner of sandwiching the leg 4b of the filament 4. Therefore, if the thermal expansion coefficients of the core material 16a, the cladding layer 16b, and the cladding layer 16c are different, the bent portion of the lead wire 16 will be opened due to the heat generated by the filament 4, and the legs 4b of the filament 4 may be detached. The lead 16, or the electrical connection between the lead 16 and the leg 4b of the filament 4 may be obstructed.

In this case, as long as the wire containing nickel is joined to one end of the lead wire 16, and the end of the wire containing nickel is bent to clamp the leg 4b of the filament 4, it is possible to prevent the bent portion from being caused by the filament 4. The heat generated and opened. However, in this case, the structure of the lead becomes complicated, leading to an increase in manufacturing cost.

The inventors of the present invention conducted studies and found that as long as the types of coating layers are reduced, the opening of the bent portion 6c can be suppressed. FIG. 4 is a schematic diagram for illustrating a cross-section of the lead of this embodiment. As shown in FIG. 4, the lead 6 includes a core material 6a and a cladding layer 6b. The core material 6a has a linear shape. The cross-sectional shape of the core material 6a is, for example, a circle. The core material 6a is formed of a material having a thermal expansion coefficient close to that of glass. The core material 6a contains iron and nickel, for example. The core material 6a can be formed of, for example, an alloy containing iron and nickel. The core material 6a can be formed of, for example, Fe-Ni alloy, Fe-Ni-Cr alloy, Fe-Ni-Co alloy, or the like.

The covering layer 6b covers the surface of the core material 6a. The coating layer 6b contains nickel. As described above, as long as the surface of the lead 6 is covered with nickel, the nickel oxide generated when the lead 6 is sealed in the sealing portion 3 diffuses into the glass, so that the lead 6 and the sealing portion 3 can be brought into close contact. In addition, since nickel is more difficult to oxidize than copper, it is possible to prevent the part of the lead 6 exposed from the sealing portion 3 from oxidizing and causing connection failure. Therefore, the clad layer 6b becomes a layer containing nickel.

The lead 6 of this embodiment has fewer types of coating layers than the lead 16 of the comparative example. Therefore, it is possible to reduce the influence of thermal stress generated when the vehicle light bulb 1 is turned on and off. As a result, it is easy to suppress the expansion of the bent portion 6c due to the heat generated by the filament 4. In addition, the structure of the lead 6 can be simplified.

However, it has been clarified that if the coating layer 16b containing copper is omitted, when the lead 6 is sealed in the sealing portion 3, air bubbles are generated in the vicinity of the lead 6. If air bubbles are generated in the vicinity of the lead wire 6, a gap is likely to occur between the lead wire 6 and the sealing portion 3, and cracks may occur. The bubbles are considered to be bubbles formed when the gas adsorbed on the core material 6a and the coating layer 6b is released when the lead 6 is sealed in the sealing portion 3. In the case of the lead wire 16 of the comparative example, since the coating layer 16b containing copper is provided, it is possible to suppress the gas adsorbed on the core material 16a from being released to the outside. However, the lead 6 of the present embodiment is not provided with the coating layer 16 b containing copper, and therefore, it is considered that bubbles are likely to be generated in the vicinity of the lead 6.

The inventors conducted research and found that after forming the core material 6a and after forming the coating layer 6b having a predetermined thickness, respectively, performing predetermined heat treatment, a lead wire 6 capable of suppressing the generation of bubbles can be obtained. Next, the manufacturing method of the lead 6 of this embodiment is demonstrated. First, the core material 6a is formed. For example, a Fe-Ni alloy melt is produced, and an Fe-Ni alloy ingot is formed by a vacuum casting method or the like. Next, a rolled wire rod is formed from an ingot by a hot rolling method or the like, and cold drawing and heat treatment are repeatedly performed on the rolled wire rod to form a core material 6a having a diameter of about 0.2 mm to 0.76 mm, for example.

Next, the first heat treatment is performed on the core material 6a. For example, a heating furnace can be used to heat the core material 6a. In this case, for example, the core material 6a can be heated to 700°C or higher in an atmosphere of _{nitrogen or hydrogen (H 2 ).} As long as the core material 6a is heated to 700°C or higher, the gas or moisture adsorbed on the core material 6a can be removed. In this case, if the core material 6a is heated to 800°C or higher, the gas or moisture adsorbed on the core material 6a can be easily removed. In addition, if the core material 6a is heated to 900°C or higher, the strain remaining in the core material 6a can be easily removed. As long as the strain remaining in the core material 6a is removed, it is easy to obtain the core material 6a having a desired coefficient of thermal expansion.

The heating time can be appropriately adjusted according to the diameter size of the core material 6a, the heating temperature, and the like. For example, when the diameter size of the core material 6a is about 0.76 mm and the heating temperature is about 900°C, the heating time can be set to about 20 seconds to 200 seconds. In addition, nitrogen is more difficult to adsorb to the core material 6a than hydrogen. Therefore, as long as the core material 6a is heat-treated in a nitrogen atmosphere, the amount of gas adsorbed to the core material 6a during cooling after heating can be suppressed. Therefore, it is more preferable to perform heat treatment on the core material 6a in a nitrogen atmosphere.

Next, a coating layer 6b is formed on the surface of the core material 6a. For example, the coating layer 6b can be formed using a film forming method such as a plating method or a sputtering method. For example, an electroplating method can be used to form a coating layer 6b containing nickel on the surface of the core material 6a. Here, as described above, the end portion of the glass bulb 2 is heated, and the heated end portion of the glass bulb 2 is pressed together with the pair of leads 6 to form the sealing portion 3. Therefore, when the sealing portion 3 is formed, the lead wire 6 is heated.

In this case, if the thickness of the coating layer 6b is too thin, when the lead wire 6 is heated, it is clearly known that the iron contained in the core material 6a is easily precipitated on the surface of the coating layer 6b. Since iron is easily oxidized, if iron is deposited on the surface of the coating layer 6b, the portion of the lead 6 exposed from the sealing portion 3 may be oxidized, resulting in connection failure. In addition, it has been clarified that if the thickness of the coating layer 6b is too thick, the bent portion 6c of the lead 6 is likely to open. The reason why the bent portion 6c of the lead 6 is easy to open is not necessarily clear, but it is considered that if the thickness of the coating layer 6b is too thick, the influence of the thermal stress will increase. According to the findings obtained by the present inventors, the thickness of the coating layer 6b is preferably 1.0 μm or more and 6.0 μm or less. In addition, the details regarding the thickness of the coating layer 6b will be described later.

Next, a second heat treatment is performed on the core material 6a having the covering layer 6b formed on the surface. For example, a heating furnace can be used to heat-treat the core material 6a on which the coating layer 6b is formed. For example, the core material 6a having the coating layer 6b formed on the surface can be heated to 700°C or higher in an atmosphere of nitrogen or hydrogen. As long as the core material 6a with the coating layer 6b formed on the surface is heated to 700°C or higher, the gas or moisture adsorbed on the coating layer 6b can be removed. In addition, it is also possible to remove gas or moisture adsorbed on the core material 6a. In this case, if the core material 6a having the coating layer 6b formed on the surface is heated to 800°C or higher, the gas or moisture adsorbed on the coating layer 6b can be easily removed. In addition, if the core material 6a having the coating layer 6b formed on the surface is heated to 800°C or higher, the gas or moisture adsorbed on the core material 6a is also easily removed. In addition, if the core material 6a having the coating layer 6b formed on the surface is heated to 900°C or higher, the strain remaining in the core material 6a can be easily removed.

In this case, if the heating time is too long, the iron contained in the core material 6a is likely to precipitate on the surface of the coating layer 6b. Therefore, the heating time of the second heat treatment is shorter than the heating time of the first heat treatment. In this case, it is possible to appropriately adjust the heating time of the second heat treatment according to the diameter size and heating temperature of the core material 6a on which the coating layer 6b is formed on the surface. For example, when the diameter of the core material 6a on which the coating layer 6b is formed is about 0.3 mm and the heating temperature is about 900°C, the heating time can be set to about 20 to 30 seconds. In addition, nitrogen is more difficult to adsorb to the coating layer 6b than hydrogen. Therefore, as long as the core material 6a having the coating layer 6b formed on the surface is heat-treated in a nitrogen atmosphere, the amount of gas adsorbed to the coating layer 6b during cooling after heating can be suppressed. Therefore, it is more preferable to perform a heat treatment on the core material 6a having the coating layer 6b formed on the surface in a nitrogen atmosphere. The lead 6 of this embodiment can be manufactured in the manner described above.

That is, the manufacturing method of the lead wire of this embodiment can include the following steps. A step of forming a core material 6a having a linear shape and containing iron and nickel. In a hydrogen or nitrogen environment, the core material 6a is subjected to the first heat treatment step. A step of forming a coating layer 6b containing nickel on the surface of the core material 6a subjected to the first heat treatment. In a hydrogen or nitrogen environment, the core material 6a on which the coating layer 6b is formed is subjected to a second heat treatment step. In this case, in the step of forming the coating layer 6b, the coating layer 6b having a thickness of 1.0 μm or more and 6.0 μm or less is formed. In addition, the heating temperature of the first heat treatment can be 700°C or higher. The heating temperature of the second heat treatment can be 700°C or higher.

Furthermore, after the second heat treatment, the core material 6a on which the coating layer 6b is formed can also be made finer. For example, by cold drawing, the diameter size of the core material 6a with the coating layer 6b formed on the surface can be further reduced. If cold drawing is performed, the core material 6a with the coating layer 6b formed on the surface will be strained. Therefore, after cold drawing, the core material 6a with the coating layer 6b formed on the surface can be further subjected to heat treatment. The conditions of the heat treatment can be the same as the conditions of the second heat treatment, for example.

Next, the first heat treatment, the second heat treatment, and the thickness of the cladding layer 6b will be further described. Table 1 and Table 2 are related to the comparative example. That is, Table 1 and Table 2 are cases where only the second heat treatment was performed and the first heat treatment was not performed. Table 1 shows the case where the second heat treatment was performed in a nitrogen environment. Table 2 shows the second heat treatment in a hydrogen environment. In the evaluation item "Bubble generation", the case where the bubbles cannot be confirmed with the naked eye is evaluated as "◎", and the case where fine bubbles can be confirmed with the naked eye, but there is no problem in the adhesion between the lead 6 and the sealing part 3 is evaluated. It is "○", and the case where bubbles can be confirmed with the naked eye and cracks are generated is evaluated as "×". In the "iron precipitation" of the evaluation item, the case where the surface of the coating layer 6b was not discolored was evaluated as "○", and the case where the surface of the coating layer 6b was discolored was evaluated as "x". In the evaluation item "Continuity", after the vehicle bulb 1 is turned on and off for a predetermined number of times in a predetermined lighting and extinguishing cycle, there is no problem with the lighting state as "○", and the case where it cannot be turned on is evaluated as "×". Furthermore, one cycle of lighting and extinguishing is set to illuminate for three minutes and extinguish for three minutes. In addition, the number of lighting and extinguishing times was set to 500 times.

[Table 1] Thickness of coating layer 6b (μm) 0 0.5 1.0 1.2 1.5 2.0 4.0 6.0 10.0 Create bubbles × × × × × × × × × Iron precipitation × × ○ ○ ○ ○ ○ ○ ○ Conduction × × ○ ○ ○ ○ ○ ○ × [Table 2] Thickness of coating layer 6b (μm) 0 0.5 1.0 1.2 1.5 2.0 4.0 6.0 10.0 Create bubbles × × × × × × × × × Iron precipitation × × ○ ○ ○ ○ ○ ○ ○ Conduction × × ○ ○ ○ ○ ○ ○ ×

According to Table 1 and Table 2, it can be seen that if the thickness of the coating layer 6b is 0.5 μm or less, the iron contained in the core material 6a is precipitated on the surface of the coating layer 6b. Since iron is easily oxidized, if iron is deposited on the surface of the coating layer 6b, the portion of the lead 6 exposed from the sealing portion 3 will be oxidized, resulting in connection failure, and failure to light up. On the other hand, if the thickness of the cladding layer 6b is 10.0 μm or more, the bent portion 6c of the lead 6 is easily opened, and lighting cannot be achieved. In addition, if the first heat treatment is not performed, the generation of bubbles cannot be suppressed.

Tables 3 to 6 are the cases where the first heat treatment and the second heat treatment were performed. Table 3 shows the case where the first heat treatment and the second heat treatment were performed in a nitrogen atmosphere. Table 4 shows the case where the first heat treatment was performed in a hydrogen environment and the second heat treatment was performed in a nitrogen environment. Table 5 shows the case where the first heat treatment and the second heat treatment were performed in a hydrogen environment. Table 6 shows the case where the first heat treatment was performed in a nitrogen environment and the second heat treatment was performed in a hydrogen environment. The evaluation items and evaluation criteria are the same as those in Table 1 and Table 2.

[table 3] Thickness of coating layer 6b (μm) 0 0.5 1.0 1.2 1.5 2.0 4.0 6.0 10.0 Create bubbles ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ ○ Iron precipitation × × ○ ○ ○ ○ ○ ○ ○ Conduction × × ○ ○ ○ ○ ○ ○ × [Table 4] Thickness of coating layer 6b (μm) 0 0.5 1.0 1.2 1.5 2.0 4.0 6.0 10.0 Create bubbles ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ ○ Iron precipitation × × ○ ○ ○ ○ ○ ○ ○ Conduction × × ○ ○ ○ ○ ○ ○ × [table 5] Thickness of coating layer 6b (μm) 0 0.5 1.0 1.2 1.5 2.0 4.0 6.0 10.0 Create bubbles ○ ○ ○ ○ ○ ○ ○ ○ ○ Iron precipitation × × ○ ○ ○ ○ ○ ○ ○ Conduction × × ○ ○ ○ ○ ○ ○ × [Table 6] Thickness of coating layer 6b (μm) 0 0.5 1.0 1.2 1.5 2.0 4.0 6.0 10.0 Create bubbles ○ ○ ○ ○ ○ ○ ○ ○ ○ Iron precipitation × × ○ ○ ○ ○ ○ ○ ○ Conduction × × ○ ○ ○ ○ ○ ○ ×

From Tables 3 to 6, it can be seen that if the thickness of the coating layer 6b is 0.5 μm or less, the iron contained in the core material 6a is precipitated on the surface of the coating layer 6b. Since iron is easily oxidized, if iron is deposited on the surface of the coating layer 6b, the portion of the lead 6 exposed from the sealing portion 3 will be oxidized, resulting in connection failure, and failure to light up. On the other hand, if the thickness of the cladding layer 6b is 10.0 μm or more, the bent portion 6c of the lead 6 is easily opened, and lighting cannot be achieved. Therefore, the thickness of the coating layer 6b is preferably 1.0 μm or more and 6.0 μm or less.

In addition, as long as the first heat treatment and the second heat treatment are performed, it is possible to suppress the generation of air bubbles in the vicinity of the lead 6 inside the sealing portion 3. As long as the generation of air bubbles can be suppressed, the generation of a gap between the lead 6 and the sealing portion 3 can be suppressed, and therefore the generation of cracks can be suppressed.

In this case, nitrogen is more difficult to adsorb to the core material 6a and the coating layer 6b than hydrogen. Therefore, in the case illustrated in Table 3 (when the first heat treatment and the second heat treatment are performed in a nitrogen atmosphere), the generation of bubbles is the least. The volume of the core material 6a is greater than the volume of the cladding layer 6b. Therefore, in the case illustrated in Table 6 (when the first heat treatment is performed in a nitrogen environment, and the second heat treatment is performed in a hydrogen environment) Produce the second least. In addition, in the case illustrated in Table 4 (when the first heat treatment was performed in a hydrogen environment and the second heat treatment was performed in a nitrogen environment), the generation of bubbles was the third least.

In addition, in the case illustrated in Table 5 (when the first heat treatment and the second heat treatment are performed in a hydrogen atmosphere), the generation of bubbles is slightly more than that in the cases illustrated in Table 3, Table 4, and Table 6, but it can be reduced. The generation of bubbles.

Fig. 5 is a graph illustrating the amount of hydrogen released from the lead. "A" in FIG. 5 is the case of the lead 6 which has not been subjected to the first heat treatment and the second heat treatment. "B" is the case of the lead 6 that has been subjected to the first heat treatment and the second heat treatment in a nitrogen atmosphere. The diameter of the lead 6 used for the measurement was set to 0.3 mm, the length was set to 10 mm, and the thickness of the coating layer 6b was set to 2 μm.

In the measurement, the TDS (temperature-rising separation analysis device) manufactured by Electronic Science (Stock), model: EMD-WA1000S/W was used. The measurement temperature range is set to 50°C to 1000°C, and the temperature increase rate is set to 60°C/min. The gas to be measured is hydrogen.

From FIG. 5, it can be seen that as long as the first heat treatment and the second heat treatment are performed, the generation of gas can be greatly suppressed. Therefore, it is possible to suppress the occurrence of air bubbles in the vicinity of the lead 6 in the inside of the sealing portion 3. As long as the generation of air bubbles can be suppressed, the generation of a gap between the lead 6 and the sealing portion 3 can be suppressed, and therefore the generation of cracks can be suppressed. Furthermore, it is considered that in "A", hydrogen generated at around 380°C is mainly adsorbed to the coating layer 6b.

Table 7 is a table for exemplifying the relationship between the peak value of the amount of hydrogen/the average value of the amount of hydrogen, and the generation of bubbles. In addition, the peak value of the amount of hydrogen is the maximum value of the amount of hydrogen released in the range of 50°C to 1000°C. The average value of the amount of hydrogen is the average value of the amount of hydrogen released in the range of 50°C to 1000°C. In addition, in the evaluation item "Bubble generation", the case where the bubbles could not be confirmed by the naked eye was evaluated as "◎", and the fine bubbles could be confirmed by the naked eye, but the adhesion between the lead 6 and the sealing part 3 was not problematic. The case was evaluated as "○", and the case where bubbles were visually confirmed and cracks occurred was evaluated as "×".

[Table 7] The peak value of the amount of hydrogen / the average value of the amount of hydrogen Create bubbles 1.0 ◎ 1.5 ◎ 2.0 ◎ 2.5 ○ 3.0 × 4.0 × 5.0 × According to Table 7, as long as (peak value of hydrogen amount)/(average value of hydrogen amount) is 2.5 or less, the generation of bubbles can be effectively suppressed. That is, when the temperature of the lead wire 6 of the present embodiment is raised to 50° C. to 1000° C. and the amount of released hydrogen is measured, (the peak value of the amount of hydrogen)/(the average value of the amount of hydrogen) is 2.5 or less.

As mentioned above, although some embodiment of this invention was illustrated, these embodiment is an embodiment shown as an example, and it is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, changes, etc. can be made without departing from the spirit of the invention. These embodiments or their modifications are included in the scope or spirit of the invention, and are included in the invention described in the scope of the patent application and its equivalent scope. In addition, each of the above-mentioned embodiments can be implemented in combination with each other.

1: Bulbs for vehicles 2: Glass bulb 3: Sealing part 3a: Exhaust pipe 4: filament 4a: coil 4b: Feet 5: Fixed parts 6, 16: Lead 6a, 16a: core material 6b, 16b, 16c: cladding layer 6c: Bending part A: In the case of lead 6 that has not undergone the first heat treatment and the second heat treatment B: In the case of the lead 6 subjected to the first heat treatment and the second heat treatment in a nitrogen environment

FIG. 1 is a schematic partial cross-sectional view for illustrating a vehicle light bulb according to this embodiment. Fig. 2 is a schematic diagram for illustrating a bent portion of a lead. Fig. 3 is a schematic diagram illustrating a cross-section of a lead of a comparative example. FIG. 4 is a schematic diagram for illustrating a cross-section of the lead of this embodiment. Fig. 5 is a graph illustrating the amount of hydrogen released from the lead.

1: Bulbs for vehicles

2: Glass bulb

3: Sealing part

3a: Exhaust pipe

4: filament

4a: coil

4b: Feet

5: Fixed parts

6: Lead

6c: Bending part

Claims (2)

A lead wire, comprising: a core material, which is linear, and contains iron and nickel; and a coating layer, which contains nickel, and directly covers the surface of the core material, and the coating layer has a thickness of 1.0 μm or more and is 6.0 μm or less, when the lead is heated to 50°C to 1000°C and the amount of hydrogen released is measured, the peak value of the amount of hydrogen/the average value of the amount of hydrogen is 2.5 or less. A light bulb for a vehicle, comprising: a glass bulb; a pair of lead wires according to claim 1; a sealing portion that seals one end of the glass bulb and holds the pair of lead wires; and a filament The inside of the glass bulb is held by the bent portion of the pair of leads.

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