Filament lamp and method of manufacturing filament lamp

Abstract

To provide a filament lamp which suppresses a filament connected to a lead rod from separating, or the filament from being broken when connected to the lead rod, and a method of manufacturing the filament lamp.SOLUTION: A filament lamp comprises: a filament constituted including a winding part of a wound wire; an inner lead rod which is in a shape extending uniaxially, has a rough surface region including a plurality of recessed parts on an outer surface in a cross section along the uniaxial direction, and is inserted into the winding part to be connected to the filament through the rough surface region; a light-emitting tube which houses the filament and the inner lead rod; and a sealing part which is formed at an end of the light-emitting tube.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a filament lamp and a method for manufacturing a filament lamp. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in image forming apparatuses such as printers and copiers, a filament lamp is used as a heat source for fixing ink on a recording medium.

[0003] In a filament lamp, a sealing portion in which a conductive member such as a metal foil is disposed is formed at the end of the arc tube in order to supply power to the filament housed in the arc tube. Then, by establishing electrical continuity between the filament and the conductive member, power can be supplied to the filament.

[0004] As shown in Patent Document 1 below, a structure is known in which a lead rod is disposed inside the arc tube in order to reduce the resistance of the conduction path between the filament and the metal foil disposed in the sealing portion. More specifically, Patent Document 1 discloses a configuration in which multiple filaments are housed in the arc tube and the filaments are connected by lead rods.

[0005] Furthermore, Patent Document 1 discloses a configuration in which a notch is provided on the outer surface of a lead rod and a filament is connected to the notch. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3873635 Summary of the Invention [Problem to be solved by the invention]

[0007] According to the configuration disclosed in Patent Document 1, after the lead rod and the filament are connected, movement of the filament in one axial direction of the lead rod is restricted, and it is thought that the filament is prevented from coming off the lead rod. However, after careful consideration, the inventors of the present invention have found that the above configuration causes the following problems.

[0008] Fig. 11 is a diagram schematically illustrating a state in which a lead rod having a notch on its outer surface is connected to a filament. As shown in Fig. 11, the lead rod 100 has a shape that extends in one axial direction and has a notch 101 on its outer surface 100a. Fig. 11 also illustrates an XYZ coordinate system in which the one axial direction is the X direction and a plane perpendicular to the X direction is the YZ plane. Using this definition, Fig. 11 corresponds to a cross-sectional view of the lead rod 100 taken along the X direction.

[0009] The lead rod 100 and the filament 102 are connected by inserting the lead rod 100 into the filament 102 and then crimping or welding the filament 102 to the lead rod 100. The lead rod 100 has a notch 101 on its outer surface 100a, which restricts movement of the filament 102 in the X direction after the two are connected, thereby preventing the filament 102 from coming off the lead rod 100.

[0010] However, in the structure shown in Fig. 11, when the filament 102 is pressed against the lead rod 100 to crimp or weld the filament 102 to the lead rod 100, the filament 102 may come into contact with the end 101a of the notch 101. In this case, the pressure applied to the filament 102 is localized, which can easily cause the filament 102 to break or snap. In other words, the inventor noticed that although the structure shown in Fig. 11 prevents the lead rod 100 and the filament 102 from separating, the filament 102 is more likely to break when they are connected.

[0011] In other words, there is room for improvement in terms of preventing the filament connected to the lead rod from coming off while also preventing damage to the filament when the two are connected.

[0012] In view of the above circumstances, the present invention aims to provide a filament lamp in which the detachment of the filament connected to the lead rod and the breakage of the filament when connecting the lead rod and the filament are suppressed. It is also an object of the present invention to provide a method for manufacturing such a filament lamp. [Means for solving the problem]

[0013] The filament lamp according to the present invention comprises: a filament including a winding portion around which a wire is wound; an internal lead rod having a shape extending in one axial direction and having a rough surface area on its outer surface including a plurality of recesses when viewed in a cross section along the one axial direction, the internal lead rod being inserted into the winding portion and connected to the filament via the rough surface area; an arc tube containing the filament and the inner lead rod; and a sealing portion formed at the end of the light emitting tube.

[0014] In this specification, the term "recess" refers to a recess that is recessed in the radial direction from the outer surface of the internal lead rod by 5% or more of the diameter of the wire that constitutes the filament.

[0015] The rough surface region to which the filament is connected includes a plurality of recesses. Therefore, with the above configuration, when the filament is pressed against the internal lead rod to crimp or weld the internal lead rod and the filament, the filament is less likely to come into local contact with the internal lead rod. In other words, since the filament is more likely to come into contact with the internal lead rod at multiple points, the pressure applied to the filament is more easily dispersed, and damage such as bending or cutting of the filament when connecting the filament to the internal lead rod is suppressed.

[0016] Furthermore, by forming a plurality of recesses on the outer surface of the internal lead rod, movement of the filament connected to the internal lead rod in the uniaxial direction is restricted, thereby suppressing detachment of the filament after connection between the internal lead rod and the filament.

[0017] Here, if the wire constituting the filament fits into the recess when the filament is pressed against the internal lead rod, the contact area between the filament and the internal lead rod increases, making it easier to disperse the pressure applied to the filament. Furthermore, fitting the wire constituting the filament into the recess more firmly prevents the filament from detaching after connection. From the viewpoint of fitting the wire into the recess, the width of the plurality of recesses in the uniaxial direction is preferably equal to or smaller than the diameter of the wire, and more preferably smaller than the diameter of the wire.

[0018] Furthermore, if the wire constituting the filament is fitted into a plurality of recesses, the amount of deformation of the filament when it is pressed against the internal lead rod is reduced, and breakage of the filament is more firmly suppressed.

[0019] The diameter of the wire may be 0.1 mm or less. By reducing the diameter of the wire, the heat capacity of the filament can be reduced, shortening the rise time of the filament lamp. From the perspective of reducing the power consumption of the image forming device in which the filament lamp is installed, it is preferable to shorten the rise time of the filament lamp. Note that "rise time" refers to the time it takes for the light output emitted by the filament lamp to reach a predetermined value after power is first supplied to the filament lamp.

[0020] It is believed that the thinner the diameter of the wire constituting the filament, the more likely the filament is to break when pressed against the internal lead rod. In contrast, as described above, the roughened surface region to which the filament is connected includes multiple recesses, making it difficult for the filament to come into localized contact with the internal lead rod. In other words, by dispersing the pressure applied to the filament, breakage of the filament when connecting the filament to the internal lead rod can be suppressed, even when the wire diameter is thin, which is preferable.

[0021] On the other hand, from the viewpoint of ensuring the strength of the filament, the diameter of the wire is preferably at least 0.01 mm or more, more preferably 0.02 mm or more, and particularly preferably 0.05 mm or more.

[0022] The filament lamp is a metal foil disposed in the sealing portion; The internal lead rod may be connected to the metal foil on the opposite side from the filament.

[0023] According to the above configuration, the filament and the metal foil are electrically connected by the internal lead rod. This configuration is preferable because, compared to when the filament and the metal foil are connected, the heat generated during lighting is less likely to concentrate on the metal foil, and heat generation at the sealing portion formed in the light-emitting tube can be reduced.

[0024] In the above filament lamp, The filament may be formed by winding a plurality of the wires.

[0025] By configuring the filament with multiple wires, the surface area of ​​the filament can be increased, thereby improving the efficiency of radiating heat generated by the filament when lit. Here, from the viewpoint of easily establishing electrical continuity between the filament, which is configured with multiple wires, and the metal foil, it is preferable that the filament be connected to an internal lead rod, and that the internal lead rod be connected to the metal foil, thereby establishing electrical continuity between the filament and the metal foil.

[0026] In the above filament lamp, The inner lead rod may be made of a material that is less hard than the material that the wire is made of.

[0027] The "hardness" of each material can be measured in accordance with JIS Z 2245 "Rockwell hardness test - Test method."

[0028] According to the above configuration, when the filament is pressed against the internal lead rod for crimping or welding, the internal lead rod is more easily deformed than the filament, which reduces the pressure on the filament and more effectively prevents breakage of the filament when the two are connected.

[0029] The filament lamp is In the region where the filament and the internal lead rod are connected, the distance between the filament and the internal lead rod when viewed in the uniaxial direction may be 0.2 mm or less.

[0030] Details will be described later with reference to FIG. 4 in the "Mode for Carrying Out the Invention" section. The greater the distance between the filament and the internal lead rod before the filament and the internal lead rod are connected, the greater the distance between the filament and the internal lead rod when viewed in the uniaxial direction. Here, if the distance before connection is large, the amount of deformation of the filament before contacting the internal lead rod increases, making the filament more susceptible to breakage. In other words, a small distance between the filament and the internal lead rod after crimping between them is complete means that the amount of deformation of the filament upon connection is small. Therefore, with the above configuration, the deformation is reduced, making it possible to suppress filament breakage.

[0031] In the above filament lamp, The recessed portion may be a groove extending in a direction intersecting with the axial direction.

[0032] The method for manufacturing a filament lamp according to the present invention comprises the steps of: A method for manufacturing a filament lamp comprising a filament including a wound portion around which a wire is wound, an internal lead rod connected to the filament, and an arc tube containing the filament and the internal lead rod, a roughened surface region including a plurality of recesses when viewed in a cross section along an axial direction in which the internal lead rod extends, is formed on an outer surface of the internal lead rod; The internal lead rod is inserted into the winding portion, and the filament and the internal lead rod are connected via the roughened surface region.

[0033] In the method for manufacturing the filament lamp, The roughened surface area may be formed by blasting the inner lead rod. [Effects of the Invention]

[0034] According to the present invention, there is provided a filament lamp in which detachment of the filament connected to the lead rod and breakage of the filament when connecting the lead rod and the filament are suppressed. Also, according to the present invention, there is provided a method for manufacturing the above filament lamp. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a cross-sectional view showing an example of an embodiment of a filament lamp. [Figure 2] FIG. 10 is a cross-sectional view of the internal lead rod taken along the X direction. [Figure 3A] FIG. 10 is a cross-sectional view showing a state in which an internal lead rod is inserted into the wound portion of the filament. [Figure 3B] FIG. 10 is a cross-sectional view showing the state in which the filament and the internal lead rod are connected. [Figure 4] This is a view of the filament and the internal lead rod as seen in the -X direction. [Figure 5A] FIG. 3 is a cross-sectional view showing another example of the internal lead rod configuration, following FIG. 2. [Figure 5B]FIG. 5B is a perspective view of the inner lead rod according to FIG. 5A. [Figure 6A] FIG. 3B is a cross-sectional view showing a state in which an internal lead rod is inserted into the wound portion of the filament, following FIG. 3A. [Figure 6B] 3B, showing the state in which the filament and the internal lead rod are connected. [Figure 7A] FIG. 5C is a perspective view showing another example of the internal lead rod configuration, following FIG. 5B. [Figure 7B] FIG. 5C is a perspective view showing yet another example of the configuration of the internal lead rod, following FIG. 5B. [Figure 8] FIG. 10 is a cross-sectional view showing the structure of a filament lamp according to a second embodiment. [Figure 9] 1 is a diagram showing another example of the configuration of a filament lamp. [Figure 10] 10 is a diagram showing yet another configuration of a filament lamp. [Figure 11] 1 is a diagram schematically illustrating a state in which a lead rod having a notch on its outer surface is connected to a filament. DETAILED DESCRIPTION OF THE INVENTION

[0036] [First embodiment] A first embodiment of a filament lamp according to the present invention will be described below with reference to the drawings as appropriate. Below, the structure of the filament lamp will be explained, and a method for manufacturing the filament lamp will be described.

[0037] It should be noted that the following drawings are schematic illustrations, and the dimensional ratios on the drawings do not necessarily match the actual dimensional ratios. Furthermore, the dimensional ratios between the drawings do not necessarily match.

[0038] Fig. 1 is a cross-sectional view showing an example of an embodiment of a filament lamp. As shown in Fig. 1, the filament lamp 1 comprises an arc tube 2, a filament 4, and internal lead rods (6, 6).

[0039] In the following drawings, an XYZ coordinate system is also shown, with the tube axis direction of the arc tube 2 being the X direction and the plane perpendicular to the X direction being the YZ plane. In the following description, when a positive or negative direction is to be distinguished when expressing a direction, it is described with a positive or negative sign, such as "+X direction" and "-X direction." When a direction is to be expressed without distinguishing between positive and negative directions, it is simply described as "X direction." In other words, in this specification, when simply referring to "X direction," it includes both the "+X direction" and the "-X direction." The same applies to the Y direction and the Z direction.

[0040] The arc tube 2 is made of a glass material such as quartz glass, etc. The internal space of the arc tube 2 is filled with an inert gas such as nitrogen or argon, as well as a halogen gas such as iodine, bromine, or chlorine.

[0041] As an example, the inner diameter of the arc tube 2 is set to 4 mm to 10 mm, and the length of the arc tube 2 in the X direction is set to 100 mm to 400 mm.

[0042] As shown in FIG. 1, the light emitting tube 2 has sealing portions (8a, 8b) at both ends in the X direction, and houses the filament 4 and the internal lead rods (6, 6).

[0043] In the sealing portion 8a, a metal foil 10 made of a metal material such as molybdenum is embedded and disposed. The metal foil 10 is connected, for example by welding, to the internal lead rod 6 and the external lead rod 12, which are disposed with portions embedded in the sealing portion. The external lead rod 12 is connected to a power supply terminal 14 by any method such as welding.

[0044] As will be described later, the internal lead rod 6 is connected to the filament 4. More specifically, the internal lead rod 6 is connected to the filament 4, and is also connected to the metal foil 10 on the opposite side of the filament 4. This allows power to be supplied to the filament 4 via the power supply terminals 14 at both ends of the light-emitting tube 2. Note that the configuration of the sealing portion 8b is the same as that of the sealing portion 8a, so a description thereof will be omitted.

[0045] The filament 4 includes a winding portion 4a around which one or more wires are wound. In this embodiment, the filament 4 is made of a single wire, and the winding axis of the single wire is in the X direction. As an example, the wire is made of a metal material such as tungsten or molybdenum.

[0046] The inner diameter C1 of the wound portion 4a when the filament 4 is viewed in the X direction is, for example, 0.4 mm to 1.2 mm.

[0047] Here, from the standpoint of reducing the heat capacity of the filament 4 and shortening the warm-up time of the filament lamp 1, it is preferable to make the diameter R1 (see FIG. 3, described later) of the wire that makes up the filament 4 small. As an example, the diameter R1 of the wire is set to 0.05 mm to 0.1 mm.

[0048] As shown in Fig. 1, the internal lead rod 6 has a shape that extends in one axial direction. This axial direction corresponds to the X direction. As an example, the internal lead rod 6 is made of a metal material such as tungsten or molybdenum. The diameter R2 of the internal lead rod 6 (see Fig. 4 described later) is, for example, 0.4 mm to 1.2 mm, which is within the range that allows the internal lead rod 6 to be inserted into the filament 4.

[0049] As shown in Fig. 1, the internal lead rod 6 has a roughened surface area A1 on its outer surface. The internal lead rod 6 is inserted into the wound portion 4a of the filament 4 and connected to the filament 4 via the roughened surface area A1. In Fig. 1, the roughened surface area A1 of the internal lead rod 6 is schematically indicated by hatching.

[0050] 2 is a cross-sectional view of the internal lead rod 6 taken along the X direction. As shown in FIG. 2, the roughened surface area A1 is an area on the outer surface 6a of the internal lead rod 6 where a plurality of recesses 20 are formed. In other words, the roughened surface area A1 includes a plurality of recesses 20 when viewed in a cross section taken along the X direction. Although FIG. 2 shows the internal lead rod 6 located on the +X side, the same discussion can be applied to the internal lead rod 6 located on the -X side.

[0051] The recesses 20 are recessed in a direction perpendicular to the X direction, i.e., in the radial direction of the internal lead rod 6, with respect to the outer surface 6a as a reference. Although the multiple recesses 20 are shown in a simplified manner in Figure 2, the depth D1 and width W1 of each recess 20 may be different.

[0052] From the viewpoint of restricting movement of the filament 4 connected to the internal lead rod 6 in the X direction, it is preferable that the depth D1 of the recess 20 is 5% or more of the diameter R1 of the wire that constitutes the filament 4.

[0053] In this embodiment, the roughened surface region A1 is a blasted surface formed by blasting. A conventionally known method, such as sandblasting, can be used as the blasting method. By using the blasting method, a large number of recesses 20 can be easily formed on the outer surface 6a of the internal lead rod 6.

[0054] As an example, the depth D1 and width W1 of the recess 20 are each set to 0.01 mm to 0.1 mm. For example, particles with a particle size of 0.5 mm to 1 mm are blasted against the internal lead rod 6, thereby forming a roughened surface region A1 on the outer surface 6a. The depth D1 and width W1 of the recess 20 can be adjusted as appropriate by changing the conditions of the blasting process. Although not shown in the figure, the width of the recess 20 in the circumferential direction of the internal lead rod 6 is approximately the same as the width W1.

[0055] Furthermore, blasting can easily form a roughened surface region A1 including many recesses 20 on the outer surface 6a of the internal lead rod 6. Specifically, blasting can make the area of ​​the region where the multiple recesses 20 are formed 80% to 90% of the area of ​​the roughened surface region A1. By forming many recesses 20 in the roughened surface region A1, the pressure applied to the filament 4 when it is pressed against the internal lead rod 6 is more easily dispersed.

[0056] The rough surface region A1 is a region spanning the region where the recesses 20 located furthest on the -X side in the X direction are formed and the region where the recesses 20 located furthest on the +X side are formed, and may refer to a region including a plurality of recesses 20. Furthermore, the "area of ​​the region where a plurality of recesses 20 are formed" may refer to the sum of the areas of the recesses 20 recessed from the outer surface 6a.

[0057] After the roughened surface region A1 is formed on the outer surface 6a of the internal lead rod 6 in this manner, the internal lead rod 6 and the filament 4 are connected via the roughened surface region A1 by crimping or welding. In the above description, the roughened surface region A1 is formed by blasting, but the method for forming the roughened surface region A1 is not limited to blasting. Specific examples will be described later.

[0058] Fig. 3A is a cross-sectional view showing a state in which the internal lead rod 6 has been inserted into the wound portion 4a of the filament 4, and Fig. 3B is a cross-sectional view showing a state in which the filament 4 and the internal lead rod 6 have been connected. Fig. 4 is a view of the filament 4 and the internal lead rod 6 as viewed in the -X direction. For convenience of illustration, Figs. 3A to 3B and 4 only show the internal lead rod 6 and filament 4 located on the +X side.

[0059] As shown in FIGS. 3A and 3B, after the internal lead rod 6 is inserted into the filament 4, the internal lead rod 6 and the filament 4 are connected. More specifically, the filament 4 is pressed against the internal lead rod 6, and the two are crimped or welded together. This causes deformation of the wire constituting the filament 4 and the contact portion e1 of the internal lead rod 6 with the filament 4, as shown in FIG. 3B. More specifically, the contact portion e1 corresponds to the outermost position of the recess 20 in the radial direction of the internal lead rod 6. FIG. 3B schematically shows the deformed states of the filament 4 and the internal lead rod 6. Also, in FIG. 4, the state of the filament 4 before it is pressed against the internal lead rod 6 is shown by a dashed line.

[0060] When connecting the internal lead rod 6 and the filament 4, as shown in Fig. 3B, pressure is applied to the filament 4, for example, in the Z direction, with the filament 4 and the multiple recesses 20 in contact with each other. Therefore, when crimping the filament 4 and the internal lead rod 6, the pressure applied to the filament 4 is dispersed, and the pressure is less likely to be applied locally to the filament 4. By dispersing the pressure, damage to the filament 4, such as bending or cutting, is suppressed.

[0061] 3B, the filament 4 fits into the multiple recesses 20. This makes it difficult for the internal lead rod 6 to come off the filament 4. From the viewpoint of fitting the filament 4 into the multiple recesses 20, the width W1 of the recess 20 is preferably equal to or smaller than the diameter R1 of the wire constituting the filament 4, and more preferably smaller than the diameter R1 of the wire.

[0062] 4, when the filament 4 is pressed against the internal lead rod 6 in the Z direction, for example, the separation distance S1 between the filament 4 and the internal lead rod 6 in the Y direction increases in the region where the filament 4 and the internal lead rod 6 are connected. Here, the separation distance S1 increases as the separation distance S2 between the filament 4 and the internal lead rod 6 before the filament 4 is pressed increases. In other words, a small separation distance S1 means that the amount of deformation of the filament 4 when connected to the internal lead rod 6 is small. Therefore, from the viewpoint of reducing the amount of deformation of the filament 4 and preventing breakage of the filament 4, the separation distance S1 is preferably 0.2 mm or less, and more preferably 0.1 mm or less.

[0063] The separation distance S1 can be adjusted appropriately by adjusting the diameter R2 of the internal lead rod 6 and the inner diameter C1 of the filament 4. Furthermore, from the viewpoint of reducing the amount of deformation of the filament 4, it is preferable that the separation distance S2 between the filament 4 and the internal lead rod 6 before crimping is small. For example, it is preferable that the separation distance S2 be 0.1 mm or less.

[0064] Furthermore, it is preferable that the hardness of the material constituting the internal lead rod 6 is lower than the hardness of the material constituting the wire constituting the filament 4. This makes it easier for the internal lead rod 6 to deform than the filament 4 when the filament 4 is pressed against the internal lead rod 6 for crimping or welding, thereby making it possible to prevent breakage of the filament 4 during connection.

[0065] As an example, the filament 4 may be made of tungsten and the internal lead rod 6 may be made of molybdenum. The filament 4 and the internal lead rod 6 may also be made of an alloy material, for example, with tungsten as the main material. In this case, the hardness of each of the filament 4 and the internal lead rod 6 can be adjusted by adjusting the composition of the alloy material. Here, the "main material" refers to the material with the highest proportion of the materials that make up the target object.

[0066] In the above description, the rough surface region A1 is formed by blasting, but the rough surface region A1 may also be formed by groove processing.

[0067] Fig. 5A is a cross-sectional view showing another example of the internal lead rod 6, following Fig. 2. Fig. 5A schematically shows a case where the rough surface region A1 is formed by groove processing. Fig. 5B is a perspective view of the internal lead rod 6 shown in Fig. 5A.

[0068] 5A and 5B, the recesses 20 may be grooves extending in the circumferential direction of the internal lead rod 6. In other words, the grooves extend in a direction intersecting with the X direction. In FIG. 5A, the rough surface region A1 includes a plurality of recesses 20, as described with reference to FIG. 2.

[0069] As described above, the width W1 of the recess 20 is preferably equal to or smaller than the diameter R1 of the wire that constitutes the filament 4, and more preferably smaller than the diameter R1 of the wire. As an example, the width W1 of the recess 20 is 0.01 mm to 0.1 mm.

[0070] Moreover, as an example, the depth D1 of the recess 20 is 0.01 mm to 0.1 mm.

[0071] 6A is a cross-sectional view showing the state in which the internal lead rod 6 is inserted into the wound portion 4a of the filament 4, following FIG. 3A, and FIG. 6B is a drawing showing the state in which the filament 4 and the internal lead rod 6 are connected, following FIG. 3B. In FIGS. 6A and 6B, as described with reference to FIGS. 3A and 3B, the filament 4 comes into contact with the multiple recesses 20, which facilitates dispersion of pressure applied to the filament 4. As a result, damage to the filament 4 during crimping is suppressed.

[0072] 6B, as a result of the connection between the filament 4 and the internal lead rod 6, the internal lead rod 6 and the filament 4 may come into contact at contact portion e2 in addition to contact portion e1. More specifically, contact portion e2 corresponds to the innermost position of the recess 20 in the radial direction of the internal lead rod 6. Contact between the internal lead rod 6 and the filament 4 at contact portion e2 in addition to contact portion e1 is preferable because it more firmly restricts movement of the filament 4 relative to the internal lead rod 6.

[0073] From the viewpoint of facilitating the formation of contact portion e2 when the filament 4 and the internal lead rod 6 are connected, the depth D1 of the recess 20 is preferably 50% or less, and more preferably 30% or less, of the diameter R1 of the wire constituting the filament 4. From the viewpoint of forming contact portion e1 and dispersing pressure on the filament 4, the depth D1 of the recess 20 is preferably 10% or more of the diameter R1 of the wire constituting the filament 4.

[0074] In the above description, the rough surface region A1 is provided on the +Z side of the internal lead rod 6. However, the rough surface region A1 may be provided on both the +Z side and the -Z side of the internal lead rod 6, or may be provided around the circumferential direction of the internal lead rod 6.

[0075] Grooving is preferable in that it is easy to adjust the width W1 and depth D1 of the recesses 20. Note that, although the recesses 20 are shown in a simplified form in Fig. 5A, the width W1 and depth D1 may be different for each recess 20. Furthermore, in Fig. 5A, it is optional whether the intervals W2 at which the multiple recesses 20 are spaced apart from one another in the X direction are constant.

[0076] The groove may be formed by cutting using a laser or the like. Various methods can be used for the groove as long as the recess 20 can be formed in the outer surface 6a of the inner lead rod 6. For example, the recess 20 may be formed by pressing any wire into the outer surface 6a of the inner lead rod 6.

[0077] Fig. 7A is a perspective view showing another example of the configuration of the internal lead rod 6, following Fig. 5B. In Figs. 5A and 5B, the recesses 20 have been described as grooves extending in the circumferential direction of the internal lead rod 6. However, as shown in Fig. 7A, the recesses 20 may be grooves extending in a direction perpendicular to the X direction.

[0078] The recess 20 may also be a spiral groove. From the viewpoint of restricting movement of the filament 4 connected to the internal lead rod 6 in the X direction and suppressing detachment of the filament 4, it is preferable that the recess 20 extends at least in a direction intersecting the X direction. The spiral groove may also be formed by pressing the filament 4 into the outer surface 6a of the internal lead rod 6 when connecting the filament 4 and the internal lead rod 6.

[0079] 7B is a perspective view showing another example of the configuration of the internal lead rod 6, following Fig. 5B. As shown in Fig. 7B, the roughened surface region A1 may be formed by forming a plurality of recesses 20 made of depressions in the outer surface 6a of the internal lead rod 6. The width of the recesses 20 in the X direction is the same as that described with reference to Fig. 5A.

[0080] Whether or not the inner lead rod 6 has a rough surface area A1 on the outer surface 6a can be confirmed by visual inspection, etc. This confirmation may be performed after disassembling the inner lead rod 6 and the filament 4.

[0081] [Second embodiment] The second embodiment of the filament lamp will be described below with reference to the drawings, focusing on the differences from the first embodiment. Explanations of the parts common to the first embodiment will be omitted where appropriate.

[0082] Fig. 8 is a cross-sectional view showing the structure of a filament lamp according to a second embodiment. This embodiment differs from the first embodiment in that the filament lamp 1 comprises a filament 4 and a filament 5, and internal lead rods 7 connected to each of the filaments 4 and 5 are disposed within the arc tube 2. As shown in Fig. 8, the arc tube 2 may contain multiple filaments (4, 5) each including a wound portion (4a, 5a).

[0083] The internal lead rod 7 has rough surface regions A2 at both ends in the X direction. As shown in Fig. 8, the internal lead rod 7 is connected to the filament 4 via the rough surface region A2 on the +X side, and is connected to the filament 5 via the rough surface region A2 on the -X side.

[0084] The same discussion as that regarding the rough surface region A1 in the first embodiment can be applied to the rough surface region A2.

[0085] 8, the filament 5 is connected to an internal lead rod 6 arranged on the -X side. This allows power to be supplied to the filaments 4 and 5 via power supply terminals 14 at both ends of the light-emitting tube 2.

[0086] [Another embodiment] Another embodiment of the filament lamp 1 will now be described.

[0087] <1> In the above description, the filaments (4, 5) are each made of a single wire. However, the filaments (4, 5) may be made of a plurality of wires wound around each other.

[0088] <2> In the above description, the inner diameter C1 of the filament (4, 5) is constant in the X direction before being connected to the internal lead rod 6. However, the inner diameter C1 of the filament (4, 5) may vary depending on the position in the X direction.

[0089] Specifically, for example, in the filament 4 shown in Fig. 1, the inner diameter of the portion into which the internal lead rod 6 is inserted may be smaller than the inner diameter of the central portion in the X direction. Also, the inner diameter of the portion into which the internal lead rod 6 is inserted may be larger than the inner diameter of the central portion in the X direction. In other words, a configuration in which the diameter R2 of the internal lead rod 6 is larger than the inner diameter of the central portion of the filament (4, 5) in the X direction is also possible.

[0090] <3> The roughened surface region A1 may be formed over any area on the outer surface 6a of the internal lead rod 6. For example, the roughened surface region A1 may be formed only on the end portion in the X direction, or may be formed over the entire outer surface 6a. The same discussion can be applied to the internal lead rod 7.

[0091] <4> Figure 9 is a diagram showing another example of the configuration of the filament lamp 1. In the above, it has been explained that the sealing portions (8a, 8b) are formed at both ends of the arc tube 2 in the X direction. However, as shown in Figure 9, it is also possible for the sealing portion 8a to be formed only on the +X side of the arc tube 2.

[0092] 9, in this embodiment, a sealing portion 8a is formed at the end portion on the +X side of the light emitting tube 2. A pair of metal foils 10 is arranged in the sealing portion 8a. An inner lead rod 6 and an outer lead rod 12 are connected to each of the metal foils 10.

[0093] The internal lead rods 6 are connected to the filaments 4. More specifically, the filaments 4 have wound portions 4b formed at their ends, and after the internal lead rods 6 are inserted into the wound portions 4b, the wound portions 4b are pressed against the internal lead rods 6 and crimped or welded. At this time, the wound portions 4b are connected via the rough surface regions A1 of the internal lead rods 6. In this case as well, the same discussion as in the first embodiment can be made regarding the rough surface region A1.

[0094] 9, the external lead rods 12 are connected to power supply terminals 14. This allows power to be supplied to the filament 4 via the pair of power supply terminals 14.

[0095] <5> Fig. 10 is a drawing showing yet another configuration of the filament lamp 1. In the above, it has been explained that the internal lead rod 6 and the metal foil 10 are connected. However, as shown in Fig. 10, it is also possible for the internal lead rod 6 to be connected to each of the filaments 4 and 5, and for the filaments 4 and 5 to be connected to the metal foil 10, respectively. In this case, from the viewpoint of facilitating the connection between the filaments (4, 5) and the metal foil 10, it is preferable that the filaments (4, 5) be made of a single wire.

[0096] <6> In the above description, the filaments (4, 5) and the internal lead rods (6, 7) are made of a metal material such as tungsten or molybdenum. However, the materials of the two components are not limited to the above, and may be any material as long as they can be connected by crimping or welding. For example, the filaments (4, 5) and the internal lead rods (6, 7) may be made of a carbon material such as graphite.

[0097] <7> In the sealing portions (8a, 8b), instead of the metal foil 10, a metal rod may be disposed, and the metal rod may be connected to the internal lead rod 6 (also called a "rod seal"). For example, the metal rod may be made of tungsten, and multiple glass layers may be wrapped around it by welding. More specifically, the thermal expansion coefficients of the multiple glass layers are set to a value close to that of tungsten on the side closer to the metal rod, and a value close to that of the arc tube 2 on the outside, i.e., on the side closer to the arc tube 2. This makes it possible to form the sealing portions (8a, 8b) at the ends of the arc tube 2 with the metal rod in place.

[0098] <8> The filament lamp and the method for manufacturing the filament lamp are not limited to the above-described embodiment. Furthermore, the configurations according to the above-described embodiments can be realized by appropriately combining them. [Explanation of symbols]

[0099] 1: Filament lamp 2: Arc tube 4,5: Filament 4a, 4b, 5a: Winding section 6,7: Internal lead rod 6a : Outer surface 8a,8b: Sealing part 10: Metal foil 12: External lead rod 14: Power supply terminal 20: Recess 100: Lead stick 100a: outer surface 101: Cutout 102: Filament A1,A2: Rough surface area C1: Inner diameter D1: Depth R1,R2: Diameter S1,S2: Separation distance

Claims

1. a filament including a winding portion around which a wire is wound; an internal lead rod having a shape extending in one axial direction and having a rough surface area on its outer surface including a plurality of recesses when viewed in a cross section along the one axial direction, the internal lead rod being inserted into the winding portion and connected to the filament via the rough surface area; an arc tube containing the filament and the inner lead rod; a sealing portion formed at the end of the light-emitting tube.

2. 2. A filament lamp according to claim 1, wherein the width of said plurality of recesses in said one axial direction is equal to or less than the diameter of said wire.

3. 3. A filament lamp according to claim 1, wherein the diameter of said wire is 0.1 mm or less.

4. a metal foil disposed in the sealing portion; 3. A filament lamp according to claim 1, wherein said internal lead rod is connected to said metal foil on the side opposite to said filament.

5. 5. A filament lamp according to claim 4, wherein said filament is formed by winding a plurality of said wires.

6. 3. A filament lamp according to claim 1, wherein said internal lead rod is made of a material having a lower hardness than the material of said wire.

7. 3. A filament lamp according to claim 1, wherein in the region where the filament and the internal lead rod are connected, the distance between the filament and the internal lead rod when viewed in the uniaxial direction is 0.2 mm or less.

8. 3. A filament lamp according to claim 1, wherein said recess is a groove extending in a direction intersecting said axial direction.

9. A method for manufacturing a filament lamp comprising a filament including a wound portion around which a wire is wound, an internal lead rod connected to the filament, and an arc tube containing the filament and the internal lead rod, a roughened surface region including a plurality of recesses when viewed in a cross section along an axial direction in which the internal lead rod extends, is formed on an outer surface of the internal lead rod; A method for manufacturing a filament lamp, characterized in that the internal lead rod is inserted into the wound portion and the filament and the internal lead rod are connected via the roughened surface area.

10. 10. A method for manufacturing a filament lamp according to claim 9, wherein said roughened surface area is formed by blasting said inner lead rod.

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