JP2016119159A - Bulb filament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bulb filament which can be small-sized while securing a light flux and the lifetime, of which the lifetime can be prolonged while securing an outline dimension and the light flux and which is capable of improving the light flux while securing the outline dimension and the lifetime.SOLUTION: A filament wire 4 is formed by spirally winding a winding wire 3 of which the diameter is smaller than that of a core wire 2, around the core wire 2 in a predetermined pitch, and a coil-shaped bulb filament 1 is formed by spirally winding the filament wire 4 in a predetermined pitch.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a filament for a light bulb, and more particularly to a coiled filament used for a light source of a light bulb.

  Conventionally, as a coil-shaped filament used for the light source of a light bulb, there is one described in Patent Document 1 disclosed under the name of “incandescent light bulb”.

  The disclosed incandescent bulb is intended to improve the luminous efficiency (light flux / power) by reducing the emission of infrared rays, and as shown in FIG. 10, the cored tungsten wire formed in a coil shape. A filament 52 formed by winding a thin wire tungsten wire 51 thinner than the core metal tungsten wire 50 around the outer periphery of the wire 50 at a pitch spaced to the visible wavelength level is fixedly supported in a bulb provided with an infrared reflecting film on the surface. It has a configuration.

  Thereby, infrared rays radiated from the cored tungsten wire 50 heated by voltage application and reflected from the surface of the bulb are reflected and absorbed by the thin wire tungsten wires 51, and the emission of infrared rays from the bulb is reduced. Efficiency is improved. That's it.

Japanese Utility Model Publication No. 5-20257

  By the way, the filament 52 having the above-described configuration is required to wind the thin wire tungsten wire 51 around the cored tungsten wire 50 at a pitch that is spaced to the visible wavelength level. As a result, it becomes difficult to uniformly wind the coil at predetermined intervals over the entire length of the coil, resulting in a decrease in winding accuracy.

  Therefore, the improvement in the target light emission efficiency is hindered, and the light emission efficiency varies among the filaments.

  Therefore, the present invention was devised in view of the above problems, and the object of the present invention is to increase the luminous flux and life by increasing the cross-sectional area to increase the amount of emitted light and increasing the surface area density to enhance the heat dissipation effect. It is possible to reduce the size in a secured state, to extend the service life while securing the outer dimensions and the luminous flux, to increase the luminous flux while securing the outer dimensions and the service life, and appropriately set the parameters. It is to realize a filament that can achieve a desired optimization by changing to.

  In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is characterized in that a filament wire formed by spirally winding a winding wire having a diameter smaller than the core wire around a core wire at a predetermined pitch is a predetermined wire. It has a coil part that is spirally wound at a pitch.

  The invention described in claim 2 of the present invention is characterized in that, in claim 1, the core wire and the winding wire both have a circular cross section.

Further, in the invention described in claim 3 of the present invention, the diameter of the core wire is d1, the diameter of the winding wire is d2, the winding pitch of the winding wire is Pd2 and When the outer diameter of the coil portion is CD, the following formulas 1 and 2 are established.
Formula 1 ... [{CD-d1- (2 * d2)} / {CD- (2 * d1)-(3 * d2)}] * d2 <Pd2 <(7 * d2)
Formula 2 ... (d2 / d1) <0.25

  According to the present invention, a winding wire having a diameter smaller than that of the core wire is spirally wound around the core wire at a predetermined pitch to form a filament wire, and the filament wire is spirally wound at a predetermined pitch to form a coiled filament. By forming this, it is possible to reduce the size while ensuring the luminous flux and life, and it is possible to extend the life while securing the outer dimensions and the luminous flux, and increase the luminous flux while ensuring the outer dimensions and the lifetime. It is possible to provide a filament for a light bulb that can be used.

It is explanatory drawing which concerns on the manufacture procedure of the filament for light bulbs of embodiment. Similarly, it is explanatory drawing which concerns on the manufacture procedure of the filament for light bulbs of embodiment. Similarly, it is explanatory drawing which concerns on the manufacture procedure of the filament for light bulbs of embodiment. Similarly, it is explanatory drawing which concerns on the manufacturing process of the coil filament of embodiment. It is the A section enlarged view of FIG. It is explanatory drawing of the filament of a comparative example. It is explanatory drawing of the filament of an Example. It is a graph of the temperature characteristic with respect to the filament of the light beam in a comparative example and an Example. It is a graph of the light emission lifetime vs. filament temperature characteristic in a comparative example. It is explanatory drawing of a prior art example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 9 (the same reference numerals are given to the same portions). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  1 to 4 are explanatory views for explaining a manufacturing procedure of a coiled filament of the present invention (hereinafter abbreviated as “filament”) used for a light source of a light bulb. The manufacturing procedure will be described below with reference to FIGS.

  First, a refractory metal (for example, tungsten) wire having a circular cross section to be the filament core wire 2 is prepared (see FIG. 1).

  Next, a winding wire 3 made of a refractory metal (for example, tungsten) wire having a diameter smaller than that of the tungsten wire of the core wire 2 and a circular cross section is prepared, and is wound around the core wire 2 in a spiral shape at a predetermined pitch. Thus, the filament wire 4 is formed (see FIG. 2).

  Finally, the filament wire 4 formed by winding the winding wire 3 around the core wire 2 is spirally wound at a predetermined pitch to form the filament 1 (see FIG. 3 (front view) and FIG. 4 (side view)).

As shown in FIG. 5 (enlarged view of part A in FIG. 3), the filament 1 manufactured through the above procedure has the diameter of the core wire 2 of the filament 1 as d1, the diameter of the winding wire 3 as d2, and the winding wire 3 When the winding pitch of Pd2 is set to Pd2 and the outer diameter of the coiled winding portion (hereinafter referred to as "coil portion") 1a of the filament 1 is CD,
(Formula 1) ... [{CD-d1- (2 * d2)} / {CD- (2 * d1)-(3 * d2)}] * d2 <Pd2 <(7 * d2)
(Formula 2) (d2 / d1) <0.25
The conditions are set so as to satisfy the following two expressions.

  In this case, Equation 1 is a setting condition for the winding pitch of the winding wire 3, and the left side thereof indicates a MIN value that is a winding pitch condition for preventing the winding wire 3 wound around the core wire 2 from overlapping or contacting. ing. This is because the overlapping or contact of the winding wire 3 makes the electrical and optical characteristics of the filament 1 unstable and shortens the lighting life, as in the case of a conventional general coiled filament consisting only of a core wire. It is for suppressing.

  Furthermore, (7 × d2) on the right side of Equation 1 indicates the MAX value that is the condition of the winding pitch of the winding wire 3. The MAX value is such that the coarser the winding pitch of the winding wire 3 is, the smaller the surface area density becomes and the heat dissipation effect is reduced. Therefore, the limit of the temperature drop of the filament temperature due to the heat dissipation effect is recognized based on the filament consisting only of the core wire. Set to value.

  Equation 2 shows the set value of the wire diameter ratio between the core wire 2 and the winding wire 3. In the filament consisting only of the core wire, the larger the wire diameter, the longer the lighting life with respect to the filament temperature tends to be longer. In the filament 1 in which the winding wire 3 is wound around the core wire 2, A relatively large wire diameter of the core wire 2 is a factor in extending the service life. Specifically, if the ratio (d2 / d1) of the wire diameter d2 of the wound wire 3 to the wire diameter d1 of the core wire 2 is 0.25 or less, the lighting life of the filament consisting only of the core wire 2 of the wire diameter d1 Can also extend the service life.

  The lighting life in this case is a comparison of the lighting life with respect to the filament temperature when the filament consisting only of the core wire and the filament 1 in which the winding wire 3 is wound around the core wire 2 are lit with the same luminous flux value. It is.

  Next, the test results of the lighting test performed for evaluating the performance characteristics of the filament 1 having the above configuration will be described below.

  In the lighting test, the filaments of Examples and Comparative Examples were used as test samples, and the performance characteristics were examined by incorporating each filament into a light bulb.

  A test sample of the filament 11 of the comparative example (see FIG. 6 (an explanatory diagram of the filament of the comparative example)) uses a filament wire 14 that does not wind a winding wire, the diameter (d1) of the filament wire 14 is 0.143 mm, and the coil The outer diameter (CD) of the portion 11a is 1.2 mm, the length of the coil portion 11a (hereinafter referred to as “coil length”) (CL) is 3.6 mm, and the number of windings of the coil portion 11a is 17 turns. .

  On the other hand, the test sample of the filament 1 of the example (see FIG. 7 (description diagram of the filament of the example)) has a configuration in which the filament wire 14 of the comparative example is the core wire 2 and the winding wire 3 is wound around the core wire 2. Thus, the diameter (d2) of the winding wire 3 was 0.013 mm, and the winding pitch (Pd2) was 0.05 mm.

Substituting the set values of the test samples of this example into the above formulas 1 and 2,
(Formula 1) ... [{((1.2 (CD))-(0.143 (d1))-(2 × (0.013 (d2)))} / {(1.2 (CD) ) − (2 × (0.143 (d1))) − (3 × (0.013 (d2)))}] × (0.013 (d2)) <(0.05 (Pd2)) <(7 × 0.013 (d2))
(Formula 2) ... (0.013 (d2)) / (0.143 (d1)) <0.25
It becomes.
Therefore, when calculating Equation 1 and Equation 2,
(Formula 1) ... 0.0153 <0.05 <0.091
(Formula 2) ... 0.09 <0.25
It becomes.
From this, it can be seen that the set values of the test samples of the examples satisfy the set conditions required for the filament 1.

  FIG. 8 shows a graph of the temperature-to-filament temperature characteristic of the light beam in the comparative example and the example of the above configuration. From the graph of FIG. 8, in all the light flux values in the range from 700 lm to 1600 lm, the examples all have a lower filament temperature than the comparative example. For example, in the light flux value of 1350 lm, the temperature of the coil portion of the filament In contrast to (P point), the example is 3250K (Q point), and the temperature of the example is 120K lower. That is, it can be seen that the temperature can be lowered with the same filament size (CD = 1.2, CL = 3.6) and the same luminous flux.

  FIG. 9 is a graph of emission lifetime versus filament temperature characteristics in a comparative example. Based on the graph of FIG. 9, when comparing the lighting life of the filament of the comparative example and the example when continuously lit with the same luminous flux, the filament temperature when illuminated with the luminous flux of 1350 lm is 3370 K as described above. The lighting life at that time is about 400 h from the graph of FIG. On the other hand, in the example, the filament temperature when lighting with a light flux of 1350 lm is 3250 K as described above, and the lighting life at that time is about 1165 h when applied to the light emission lifetime vs. filament temperature characteristics of the graph of FIG. I can read. Therefore, it is estimated that the light emission lifetime when continuously lit with the same luminous flux is about three times as long as that of the comparative example.

  When the lighting life test was actually performed at 1350 lm (3250 K) for the example, a result of 970 h was obtained, and it was confirmed that the lighting life was twice as long as that of the comparative example.

  In addition, a temperature drop of about 20K was confirmed for a filament in which the winding pitch of the coil portion of the filament of the comparative example was reduced to increase the number of windings from 17 turns of the comparative example. However, this embodiment does not extend to this example.

  As described above, the filament for light bulb of the present invention forms the filament 1 by spirally winding the filament wire 4 formed by winding the winding wire 3 having a diameter smaller than that of the core wire 2 around the core wire 2 at a predetermined pitch. .

  Therefore, the filament of the present invention increases the effective surface area and increases the amount of emitted light as much as compared with a general filament having a conventional structure using a filament wire in which no winding wire is wound. Therefore, the emissivity of the filament is increased, and the temperature rise is suppressed accordingly.

  Therefore, it is possible to reduce the size while maintaining a predetermined luminous flux maintenance factor and lighting lifetime, and it is possible to extend the lifetime while maintaining a predetermined outer dimension and luminous flux maintenance factor. It is possible to increase the luminous flux in a state in which

  In addition, various specifications required for the filament can be optimized by setting appropriate setting values using the above-described external dimensions, luminous flux maintenance factor, and lighting life as parameters.

  Note that the material of each of the core wire and the winding wire forming the filament is not limited to tungsten, and other materials can be used as long as they are refractory metals as described above.

  The bulb filament of the present invention is used as a light source of various bulbs such as halogen bulbs and incandescent bulbs used for vehicle lamps.

DESCRIPTION OF SYMBOLS 1 ... Filament 1a ... Coiled winding part (coil part)
2 ... Core wire 3 ... Winding wire 4 ... Filament wire 11 ... Filament 11a ... Coiled winding part (coil part)
14 ... Filament wire

Claims (3)

  A filament for a light bulb comprising: a filament wire formed by winding a winding wire having a diameter smaller than that of the core wire spirally around the core wire at a predetermined pitch, the coil wire being spirally wound at a predetermined pitch .   2. The bulb filament according to claim 1, wherein each of the core wire and the winding wire has a circular cross section. When the diameter of the core wire is d1, the diameter of the winding wire is d2, the winding pitch of the winding wire is Pd2, and the outer diameter of the coil portion is CD, the following formulas 1 and 2 are satisfied. The filament for light bulbs according to claim 1 or 2.
Formula 1 ... [{CD-d1- (2 * d2)} / {CD- (2 * d1)-(3 * d2)}] * d2 <Pd2 <(7 * d2)
Formula 2 ... (d2 / d1) <0.25

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