JP2003031031A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation wire of high flexibility and reliability. SOLUTION: A plurality of element wires are twisted on a concentric circle to constitute a central conductor, the periphery of which is coated for insulation. The central conductor is structured so that at least each element wire located at the outermost periphery has smaller mechanical strength than those at the center.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an insulated wire,
In particular, the present invention relates to an insulated electric wire having a high bending resistance, including a connection portion by soldering such as a high voltage lead wire of a backlight for a liquid crystal display (LCD).

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices (LCDs) have been rapidly developing, and the screens are becoming larger. Under such circumstances, the frame width is being reduced.
By the way, in a liquid crystal display device, a frame portion around the screen is usually used as a wiring space, and this frame portion is also used as a space for electrically connecting with a cold cathode tube called a backlight. .

[0003]

However, as described above, the frame width is steadily shrinking, and the space for wiring and connection is also extremely narrow. Therefore, the bending angle (curvature) of the lead wire becomes an acute angle, and especially when the lead wire outside the frame is moved in the vicinity where the conductor of the lead wire is fixed by soldering to the cold cathode tube, the disconnection of the lead wire is defective at the connection part. However, there is a problem that is likely to occur.

For example, in the case of a notebook type personal computer, as shown in FIG.
From the inverter circuit 105 arranged in the main body 100 to the cold cathode tube 106 that constitutes the backlight of the display unit 101 via the low voltage side lead wire 107a and the high voltage side lead wire 107b. It is designed to be energized. The cold cathode tube 106 or the reflection plate 109 as described above is arranged in the frame portion 104 around the liquid crystal display portion 103 of the display portion 101, as shown in FIG.

However, in recent years, as shown in FIGS. 8 (a) and 8 (b), which show a comparative example between the recent display unit and the conventional display unit, the frame width tends to be miniaturized, and accordingly, the wiring space is also reduced. There is. Therefore, as shown in FIGS. 7 (a) and 7 (b), a comparative example of a soldering portion in a display unit in recent years and in the related art, the lead wire length, which was about 10 cm in the past, is reduced to about 5 cm. The soldering portion 108 for connecting the wire 107b and the cold cathode tube 106 is likely to receive a large force, and there is a problem that the soldering portion is likely to be broken.

Therefore, various countermeasures have been considered. (1) The diameter of the wire constituting the central conductor is reduced to form an electric wire with a high degree of freedom of movement between the wires. (2) Increase the strength of the central conductor. Etc. are being attempted. However, with the former, it was difficult to obtain satisfactory bending resistance in terms of manufacturing and cost. Regarding the latter, there is a problem that a disconnection occurs at the time of manufacturing the central conductor, or even if the manufacturing is possible, the finished product bundle is twisted. Therefore, a method of softening the strand itself has also been proposed, but by softening the strand, disconnection at the time of manufacturing the central conductor, twisting of the finished product can be suppressed, but the strength decreases,
No improvement in bending resistance such as measures against disconnection was observed.

[0007] As described above, the disconnection failure in a portion such as a soldering portion where a bending force is easily applied is a very serious problem. In the liquid crystal display device, this is a serious problem that prevents the reduction of the frame width, and thus a serious problem that prevents the miniaturization of the liquid crystal. Further, not only liquid crystals but also other devices are being miniaturized, and since they are often used for bending portions, the demand for insulated wires having high bending resistance is increasing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an insulated wire having high bending resistance and high reliability.

[0009]

Therefore, in the present invention, a plurality of strands are twisted on a concentric circle to form a central conductor, and the periphery of the central conductor is insulated and coated. It is characterized in that at least each strand located on the outermost periphery has a mechanical strength smaller than that of the strand located at the center.

According to this structure, the curvature is high with respect to bending, and the mechanical strength is small at the outermost periphery where the amount of strain is large, so that bending is easy. Furthermore, since sufficient mechanical strength is maintained in the central portion, bending resistance can be maintained to the maximum, and an insulated wire with high mechanical strength and high reliability can be obtained. Therefore, it is possible to prevent a disconnection defect, particularly a disconnection defect at the connection portion. Also, when forming a twisted structure, the curvature of the wire is large and the amount of strain is large. The mechanical strength of the wire forming the outermost circumference is small, so the stress against twisting is small and a twisted structure with higher strength is formed. It becomes possible to do.

Preferably, the strands are formed to have the same composition but different composition ratios.

According to this structure, the strands are made of the same material and have different compositions. For example, the mechanical strength is reduced at the outermost circumference by changing the composition ratio while the composition of the alloy is the same. Since it is formed, in addition to the above-mentioned effects, it is possible to enhance the adhesiveness when forming the twisted structure.

Preferably, the strands are made of the same material and have the same composition.

According to this structure, the strands are made of the same material and have the same composition. For example, the components and the component ratios are the same,
By changing the crystal structure, the mechanical strength is changed, and since the mechanical strength is formed so as to be small at the outermost circumference, in addition to the above effect, the difference in thermal expansion coefficient can be suppressed to an extremely small value. It is possible to improve heat resistance.

It is desirable that at least the wire constituting the outer peripheral portion of the wire is softened by annealing.

According to this structure, the manufacturing is easy and
Since various physical characteristics can be made as close as possible between the individual strands, it is possible to further improve reliability.

Preferably, the element wires are formed so as to have different crystal states. Here, the crystalline state refers to the size of crystal grains, the bonded state, and the like.

According to this structure, by making the crystal states different, for example, even if the components and the component ratios are the same,
The mechanical strength can also be changed, and since the mechanical strength is formed so as to be small at the outermost periphery, in addition to the above effects, the difference in thermal expansion coefficient can be suppressed to an extremely small value.
It is possible to improve heat resistance. Needless to say, the materials and compositions may be different and the crystalline state may be different.

More preferably, the central conductor is formed by twisting one first strand forming the central portion and six second strands having a mechanical strength smaller than that of the first strand. It is characterized by including a structure.

According to this structure, it is possible to form a twisted structure having a close-packed structure and higher mechanical strength.

[0021] Preferably, the central conductor is formed by twisting one first strand forming a central portion and a first strand twisted on a first circumference centered on the center of the first strand. And an intermediate layer composed of a twisted structure of two strands of wire, and a third strand located outside the intermediate layer and twisted on a second circumference centered on the center of the first strand. An outer layer formed of a twisted structure of an element wire, wherein the third element wire has a mechanical strength smaller than that of the first and second element wires.

According to this structure, it is possible to form a twisted structure having a close-packed structure and higher mechanical strength.

Preferably, the elongation of the second strand forming the intermediate layer is larger than that of the first strand. Here, the elongation means elongation at break.
That is, it means the amount of elongation at the time of breaking.

According to this structure, the first layer forming the intermediate layer
Since the elongation of the second strand is larger than that of the first strand, it is possible to prevent a large stress from being applied to the first strand in the central portion, and the reliability is improved. It is possible to obtain an insulated wire with high quality.

More preferably, the first layer constituting the outer layer is
The strand of No. 3 is characterized in that its elongation is larger than that of the second strand which constitutes the intermediate layer.

According to this structure, the third strand forming the outer layer is further elongated than the second strand forming the intermediate layer. It is possible to prevent a large stress from being applied to the constituent wires, and it is possible to obtain a more reliable insulated wire.

Preferably, the outer layer is twisted so that its elongation is smaller than that of the intermediate layer to form a twisted structure.

According to this structure, the elongation of the outer layer as a whole constituting the twisted structure is smaller than that of the intermediate layer as a whole. It is possible to prevent stress, and it is possible to obtain a more reliable insulated wire.

Preferably, the first to third strands are made of a tin-plated copper alloy, and the first and second strands have a mechanical strength Ts of 60 to 90 kgf / mm ^2. The third wire is softened and has a mechanical strength Ts of 20-
It is characterized in that it is 35 kgf / mm ² .

According to such a structure, it is possible to obtain an insulated wire having higher bending resistance from various experimental results. The mechanical strength Ts of the first and second strands is 60
If it is less than kgf / mm ² , sufficient bending resistance cannot be obtained, and if it exceeds 90 kgf / mm ² , the entire wire becomes hard and the wiring workability deteriorates. Also the third wire softening process is performed mechanical strength Ts is decreased bending resistance is less than 20 kgf / mm ^2, or become easily broken at the time the conductor preparation exceeds 35 kgf / mm ^2, was completed There is an inconvenience that the bundle of electric wires is twisted.

Desirably, the central conductor is a twisted structure made of the same elemental wire as a material, and is subjected to a modification treatment so that the mechanical strength gradually decreases from the central part toward the outer layer. It is characterized by being composed of lines.

According to this structure, it is possible to obtain an insulated electric wire with less stress. Further, it is only necessary to carry out a reforming treatment such as an annealing treatment after forming a twisted structure using the same strands as a material, and the manufacturing is extremely easy. In addition, it is sufficient to perform an annealing treatment prior to mounting the insulating jacket on the conventional twisted structure, which greatly simplifies the manufacturing process.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, the insulated wire according to the first embodiment of the present invention includes a first strand 1c made of one tin-plated copper alloy wire that constitutes a central portion, and a first strand 1c. An intermediate layer composed of a twisted structure of a second element wire 1 m consisting of six tin-plated copper alloy wires twisted on a first circumference centered on the center, and further positioned outside the intermediate layer And an outer layer formed of a twisted structure of a third element wire made of a tin-plated copper alloy wire twisted on a second circumference around the center of the first element wire, The third strand is characterized by having lower mechanical strength than the first and second strands.

Here, the first and second strands have a mechanical strength Ts of 70 kgf / mm ² , and the third strand is softened to have a mechanical strength Ts of 25 to 30 kgf / m 2.
m ² . And the outside of this twist structure is XLFRP
It is covered with an insulating jacket 2 made of cross-linked flame-retardant polyethylene called E. Each of the first to third strands is made of an insulating coated strand having a diameter of 0.08 mm.

This insulated wire is subjected to a twisting process as shown in the explanatory view of FIG. 2, and the six second strands 1m forming the intermediate layer are sequentially formed on the first strand 1c at the center by the die D2. It is sent while forming a twisted structure, and further 12 third strands 1o are sent on the outer side while forming a twisted structure with a die D1, and at the downstream portion, there are 19 close-packed twisted structures. Is formed, and the outer side thereof is covered with the insulating jacket 2.

The high-voltage side lead wire 7b thus formed is soldered to the terminals (Dumet wire) of the cold cathode tube 106 at the solder connection portion 108, as shown in FIG. In this case, the high-voltage side lead wire 7b has a length of about 5 cm, and is stripped at its tip from the insulating jacket 2 and bent in a loop shape.
Solder connection is made in a state where the ends of the terminals of the cold cathode tubes 106 are inserted into the loop.

The bending strength of the high-voltage side lead wire 7b thus formed was measured by using a test apparatus as shown in FIG. As a sample, the one near the tip of the high voltage side lead wire 7b is sandwiched between two mandrels having a diameter of 12.5 mm, and a load of 0.1 kg, 0.5 kg and 1.0 kg is attached to the lower end thereof. Then, the reciprocating motion AB passing the points B and C 90 degrees to the left and right from the upper end A
The number of cycles until breakage was measured with -A-C-A as one cycle. The results are shown in Table 1 below.

[0038]

[Table 1]

From these results, the insulated wire of the present invention is 3 times better than the insulated wire of the conventional type, which is composed of the same strand.
It shows that the bending resistance is about double, and that it has sufficient bending strength. Here, in the conventional type insulated wire, all of the first to third strands are the same as the first and second strands used in the present invention.

Further, as shown in Table 2 below, it can be seen that the breaking strength, which was about 2.95 kg in the related art, is significantly improved to 4.90 kg.

[0041]

[Table 2]

When the high-voltage side lead wire 7b thus formed is used in the liquid crystal display device shown in FIG. 7A,
It can be seen that the insulated wire has a long life and high reliability even though the wiring space is narrow and the bending angle is acute.

Further, it was found that there was no abnormality even at a high temperature of 105 ° C. to 150 ° C. and it also had heat resistance.

The method of manufacturing the conductor is not limited to that shown in FIG.
The layer twisting step may be performed as a separate step.

Next, a second embodiment of the present invention will be described. In the first embodiment, the first strand 1c forming the central portion and the second strand 1m forming the intermediate layer have the same mechanical strength, and the third strand forming the outermost layer. Although only 1o is composed of a wire having a small mechanical strength, the second embodiment is such that the mechanical strength is gradually reduced toward the outer layers from the first to the third wires. explain. That is, as shown in FIG. 4, the first strand 1c has a mechanical strength Ts of 70 kgf / mm ² , the second strand 1 mm has a mechanical strength Ts of 60 kgf / mm ² , and the third strand 1o has Mechanical strength Ts is 25-30kgf /
mm ² . The other structure was constructed in exactly the same way as the first embodiment.

With such a structure, it is possible to obtain a lead wire having higher bending resistance.

It is desirable that the second strand constituting the intermediate layer is twisted so that its elongation is larger than that of the first strand to form a twisted structure.

According to this structure, the elongation of the second element wire forming the intermediate layer is larger than that of the first element wire. It is possible to prevent a large stress from being applied to the wire, and it is possible to obtain a more reliable insulated wire.

Furthermore, it is desirable that the outer layer is twisted so that its elongation is larger than that of the intermediate layer to form a twisted structure.

With the above structure, the elongation of the outer layer as a whole constituting the twisted structure is larger than that of the intermediate layer as a whole. It is possible to prevent a large stress from being applied, and it is possible to obtain a more reliable insulated wire. Also, regarding the elongation of the strand, it is desirable that the third strand be larger than the stretch of the first and second strands.

Further, the central conductor is formed of a twisted structure made of the same element wire, and is subjected to a modification treatment so that the mechanical strength gradually decreases from the central part toward the outer layer. May be.

According to the above structure, it is possible to obtain an insulated electric wire with less stress. Further, it is possible to perform a reforming treatment such as an annealing treatment after forming a twisted structure using the same strands as a material, and the manufacturing is extremely easy. Further, it is possible to perform only the annealing treatment prior to mounting the insulating jacket on the conventional twisted structure, which greatly simplifies the manufacturing process.

Further, according to this structure, there is no inconvenience that the center line 1c is pulled by the elongation of the intermediate layer and the outer layer and is broken, resulting in disconnection. Furthermore, since the twist pitches of the middle layer and the outer layer are adjusted so as not to exceed the extension of the center line 1c, the center line 1c is pulled by the extension of the outer layer and breaks, resulting in a disconnection. Such inconvenience disappears.

In addition, if the material and twist pitch of these wires are selected so as not to exceed the elongation of the inner layer, each wire is pulled by the elongation of the outer layer and ruptures, resulting in disconnection. The inconvenience of causing

In the first embodiment, the first
The tin-plated copper alloy wire is used as the third element wire, but the material is not limited to this, and it is desirable to use a material having high conductivity and high tensile breaking strength.

Further, the first element wire forming the central layer and the second element wire forming the intermediate layer are made of a tin-plated copper alloy (70 kg
f / mm ² ), the third element wire forming the outer layer is annealed copper (soft copper: 20 kgf / mm ² ), and other structures similar to those of the first embodiment are also effective.

Furthermore, the first element wire forming the center layer is made of stainless steel (SUS304: 80 kgf / mm ² ),
The second element wire that constitutes the intermediate layer is a tin-plated copper alloy (70k
gf / mm ² ), the third element wire forming the outer layer is a tin-plated copper alloy (30 kgf / mm ² ), and the other structure is the same as that of the first embodiment.

Furthermore, the first element wire forming the center layer and the second element wire forming the intermediate layer are made of a tin-plated copper alloy (8
5 kgf / mm ² ), the third element wire constituting the outer layer is a tin-plated copper alloy (30 kgf / mm ² ), and the other structure is the same as that of the first embodiment.

In the first embodiment, the solder connection part peels off the insulating jacket, forms a loop with the central conductor, inserts the dumet wire into the loop, and secures it with solder. It goes without saying that a solder mass may be formed on the core and the center conductor may be inserted into the core to cure the mass.

The insulating material is not limited to the cross-linked flame-retardant polyethylene, but silicone, cross-linked fluororesin, cross-linked polyvinyl chloride or the like may be used.

[0061]

As described above, according to the insulated wire of the present invention, a plurality of insulation-coated wires are twisted in a concentric circle to form a central conductor, and the periphery of the central conductor is surrounded. It is easy to bend because the insulation coating is applied and at least each wire located at the outermost circumference has a small curvature at the outermost circumference where the curvature increases and the amount of strain increases in bending, resulting in easy bending. The part maintains sufficient mechanical strength.

Therefore, it is possible to maintain the bending resistance to the maximum and to obtain an insulated electric wire having high mechanical strength and high reliability. Therefore, it is possible to prevent a disconnection defect, particularly a disconnection defect at the connection portion. Further, even when forming a twisted structure, the mechanical strength of the wire forming the outermost circumference, which has a large curvature and a large amount of strain, is small, so the stress against twisting is small, and a twisted structure with a higher strength can be obtained. Can be formed.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing an insulated wire according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a manufacturing process of the insulated wire according to the first embodiment of the present invention.

FIG. 3 is a principal part explanatory view showing a connection portion with a cold cathode tube using the insulated wire of the first embodiment of the present invention.

FIG. 4 is an explanatory sectional view showing an insulated wire according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a laptop computer using a liquid crystal display device.

FIG. 6 is an explanatory diagram showing a liquid crystal display unit of the computer.

FIG. 7 is a comparative diagram showing changes in the connection structure of the liquid crystal display unit.

FIG. 8 is a comparative diagram showing a size change of a liquid crystal display unit.

FIG. 9 is an explanatory view of an apparatus for measuring bending strength.

[Explanation of symbols]

1c First strand 1m second strand 1mm second strand 1o Third strand 2 Insulation jacket 7b High voltage side lead wire 100 main body 101 display unit 103 LCD display 104 frame part 105 Inverter circuit 106 cold cathode tube 107a Low voltage side lead wire 107b High voltage side lead wire 108 Solder connection part 109 reflector

Continued front page    (72) Inventor Masaru Kambayashi             Sumitomo Electric 3-3 Satsukicho, Kanuma City, Tochigi Prefecture             Kanto Manufacturing Co., Ltd. F-term (reference) 5G311 AB01 AB04 AB06 AD03

Claims (12)

[Claims] 1. An insulated electric wire comprising a plurality of strands twisted on a concentric circle to form a central conductor, and an insulating coating around the central conductor, wherein the central conductor is provided at least at the outermost periphery. An insulated electric wire, wherein each of the positioned wires is configured to have a mechanical strength smaller than that of the wire positioned at the center. 2. The insulated wire according to claim 1, wherein the wires have the same composition but different composition ratios. 3. The insulated wire according to claim 1, wherein the strands are made of the same material and have the same composition. 4. The insulated wire according to any one of claims 1 to 3, wherein at least the element wire forming the outer peripheral portion of the element wire is softened by annealing. 5. The insulated wire according to claim 1, wherein the wires have different crystal states. 6. The twisted structure in which the central conductor is composed of one first strand forming a central portion and six second strands having mechanical strength smaller than that of the first strand. The insulated wire according to any one of claims 1 to 5, further comprising: 7. The center conductor includes a first first wire forming a central portion and a first wire centered on the center of the first wire.
An intermediate layer composed of a twisted structure of a second element wire twisted on the circumference of 1 and further positioned outside the intermediate layer,
An outer layer formed of a twisted structure of a third strand that is twisted on a second circumference around the center of the first strand, the third strand being the first and the second strand. 7. The insulated wire according to claim 1, which has a mechanical strength smaller than that of the second strand. 8. The insulated wire according to claim 6, wherein the second strand forming the intermediate layer has a larger elongation than that of the first strand. 9. The third strand forming the outer layer has a larger elongation than that of the second strand forming the intermediate layer. Insulated wire described in. 10. The twisted structure is formed by twisting the outer layer so that its elongation is smaller than that of the intermediate layer, thereby forming a twisted structure. Insulated wire. 11. The first to third strands are made of a tin-plated copper alloy, and the first and second strands have a mechanical strength Ts of 60 to 90 kgf / mm ² . The strand of 3 is softened and has a mechanical strength Ts of 20 to 35 kgf.
/ Mm ² The insulated wire according to any one of claims 7 to 10, characterized in that 12. The central conductor is a twisted structure made of the same elemental wire as a material, and is subjected to a modification treatment so that the mechanical strength gradually decreases from the central portion toward the outer layer. The insulated electric wire according to claim 1, wherein the insulated electric wire is provided.