JP2002110325A - Tubular heater, fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular heater, a fixing device and an image forming device with which an attaching operation of a filament is easy, and also there is little fear of a breaking of and displacement of a filament. SOLUTION: The tubular heater 1 is equipped with a filament 5 having a densly wound heat generating coil part 9, leg coil parts 10, 11 wound more loosely on both ends 2A, 2B of the heat generating coil part 9 and have smaller spiral diameter than that of the heat generating coil part 9, and attaching coil parts 12 densely wound on one end of each leg coil parts 10, 11, and connectors 4, 4 each having a stepped part 4b formed to be inscribed with the attaching coil part 12 of the filament 5 bent from an end of linear part 4a. The attaching coil parts 12, 12 are welded to the stepped parts 4b, 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a tubular heater, a fixing device, and an image forming apparatus using a tubular valve whose both ends are open.

[0002]

2. Description of the Related Art Tubular heaters are used in fixing devices such as copying machines and printers. Conventionally, as a tubular heater,
Generally, a halogen lamp was used. This halogen lamp is a lamp in which an inert gas containing a small amount of halogen is sealed in a quartz tube in which a tungsten filament is disposed, and a seal structure using molybdenum foil is formed at both ends of the quartz tube. I have. However, in recent years, a tubular heater that does not require a halogen gas or the like and does not have a seal structure using molybdenum foil has been adopted. Such a tubular heater is, for example, 29652
It is used in a fixing device disclosed in Japanese Patent No. 32 (Prior Art 1), and the fixing device is configured as shown in FIG.

A fixing device 50 shown in FIG. 4 includes a cylindrical heat roller body 51 which is open at both ends and is rotatably supported;
The lamp body 52 includes a lamp body 52 for heating the heat roller body 51 and lamp holders 53 for supporting the lamp body 52 so as to be located inside the heat roller body 51. The lamp body 52 includes a cylindrical quartz tube 54 having both ends opened, a nichrome wire 55 as a filament stretched in the quartz tube 54, and caulking terminal portions 56, 56 for fixing both ends of the nichrome wire 55, respectively. A cylindrical body having flanges 57a, 57a having outer diameters substantially equal to the diameter of the heat roller body 51 on its outer periphery, wherein the support portions of the caulking terminals 56, 56 and the flanges 57a, 57a are integrally formed; Each of the crimping terminal portions 56, 56 is supported by a nichrome wire 55, and a holder portion 57 is fitted into each end opening of the quartz tube 54.

The lamp body 52 is provided with a nichrome wire 5 in a quartz tube 54 through caulking terminals 56 made of stainless steel or the like.
5 with a stretched structure, no need for halogen gas, etc.
Since there is no sealing structure with molybdenum foil,
An inexpensive tubular heater can be obtained.

A similar tubular heater is known as 32532
No. 43, U.S. Pat.
The structure is shown in FIG. As shown in FIG. 5, the tubular heater 58 is configured such that a nichrome wire 60 as a filament disposed in a quartz tube 59 is fastened by a crimp terminal 61 also serving as a connection terminal, and the crimp terminal 61 is supported by a holder 62. I have.

[0006]

The lamp body 52 of the prior art 1 is spirally symmetrical with respect to the center axis of the quartz tube 54 when one end of the nichrome wire 55 is fixed by the caulking terminal portion 56. Since the nichrome wire 55 is provided, the caulking operation requires time and effort. Also, the nichrome wire 55
Are the same in the longitudinal direction, so when the nichrome wire 55 is pulled in the longitudinal direction, or
When an impact or vibration is applied to the nichrome wire 55, stress is applied to the nichrome wire 55, and the nichrome wire 55 may be displaced or may be disconnected at the crimp terminal portion 56 or the like.

The prior art 2 tubular heater 58 also has the same disadvantages as described above.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tubular heater, a fixing device, and an image forming apparatus in which the filament mounting operation is easy and the filament is not easily broken or misaligned.

[0009]

According to the present invention, there is provided a tubular heater having a tubular valve having both ends open; a cylindrical portion formed smaller than the inner diameter of the tubular valve; And has a flange formed to be larger than the inner diameter of the tubular valve and engaged with the tubular valve, and a through hole passing through the cylindrical portion, and the cylindrical portion is inserted into the tubular valve. An electrically insulating cap disposed at both ends of the tubular valve as described above; a heating coil portion densely spiraled, and spirally wound at both ends of the heating coil portion and having a spiral diameter of the heating coil portion. A filament disposed longitudinally within the tubular valve, having a leg coil portion smaller than the diameter and a tightly coiled mounting coil portion at one end of each leg coil portion; and a straight line penetrating through the through hole of the cap. Part A connector which is bent from one end of the linear portion and is formed so as to be inscribed in the mounting coil portion of the filament, and a connecting portion in which the mounting coil portion of the filament is welded to the step portion and electrically connected thereto; ; Characterized by having;

The heating coil, the leg coil, and the mounting coil are spirally wound so that their coil pitches have a relatively dense and sparse relationship. For example,
The heating coil portion and the mounting coil portion have a pitch of 150 to 200%, and the leg coil portion has a pitch of 1000%. Here, the percentage pitch is a ratio between the coils to the filament diameter of the filament. For example, a 100% pitch means that the filament wires are spiraled so as to contact each other, and a 200% pitch means that the filaments are spiraled with a gap of one filament wire between the coils.

The heating coil section is a main heating section of the tubular heater, and heat generated from the heating section is applied to the irradiation target. The leg coil portions are provided to reduce heat generation at both ends of the tubular heater and to reduce the influence of heat on various supporting members disposed at both ends of the tubular valve.
The mounting coil sections are provided at both ends of the filament and connected to the connectors in order to supply power to the filament from the outside.

When the step portion of the connector is formed so as to be inscribed in the mounting coil portion of the filament, the central axis of the filament substantially coincides with the central axis of the tubular valve. Therefore,
The step between the linear portion and the step portion of the connector may be appropriately set according to the spiral diameter (inner diameter) of the filament. Further, the step portion of the connector is inscribed in a plurality of filaments of the filament in the coil mounting portion of the filament, and two or more of these wires are welded at the step portion. As a result, the filament can be easily welded to the step portion, and the attachment of the filament to the connector becomes strong.

Since the cap is not fixedly disposed at both ends of the tubular valve, it can be pulled in the longitudinal direction of the tubular valve. Accordingly, the filament is also pulled in the longitudinal direction. When the tension is released, the filament vibrates. In addition, the filament also generates vibration or the like due to impact or the like.

The leg coil portion is spirally sparsely formed and has a spiral diameter smaller than the spiral diameter of the heat generating coil portion. Have. As a result, even if the heating coil portion vibrates in the longitudinal direction due to vibration or the like due to tension or impact of the filament, the vibration is suppressed. If the spiral diameter of the leg coil part is equal to the spiral diameter of the heating coil part, when the heating coil part vibrates in the longitudinal direction, the vibration is transmitted to the leg coil part, and further, the mounting coil part and the step part of the connector Therefore, the filament may be broken at the welding point. In addition, when the heating coil portion vibrates in the longitudinal direction, the coil may be displaced, and uneven heating may occur. Therefore, since the leg coil portion is sparsely spiraled and the spiral diameter is formed smaller than the spiral diameter of the heating coil portion, the leg coil portion suppresses vibration and the like. The displacement of the coil at the position is prevented.

According to the present invention, since the step portion of the connector is formed so as to be inscribed in the mounting coil portion of the filament, the filament can be easily welded to the step portion, and the center axis of the tubular valve and the center of the filament can be welded. The axes are approximately coincident. In addition, even if vibration or the like due to tension, impact, or the like is applied to the filament, the leg coil portion suppresses vibration or the like, so that disconnection of the filament at a welding location and displacement of the coil at the heating coil portion are prevented.

According to a second aspect of the present invention, in the tubular heater according to the first aspect, the helical diameter of the leg coil portion of the filament has an outer diameter of 3.0 to 5.5 mm, and the helical diameter of the heating coil portion is The outer diameter of the spiral is 6.0-7.0m
m.

The helical diameter of the filament may be within the above numerical value for each helical diameter. The wire diameter is not particularly limited, but is, for example, 0.5 mm.

The outer diameter of the helical diameter of the heating coil portion is 6.0 to 6.0.
The reason why the thickness is set to 7.0 mm is that this is an optimum value that can reduce the size of the tubular heater and obtain a sufficient amount of generated heat.
The helical diameter of the leg coil portion of the filament is relatively smaller than the helical diameter of the heating coil portion.
These numerical values allow a slight deviation such as a manufacturing error.

When the helical diameter of the leg coil portion is smaller than the helical diameter of the heating coil portion, the leg coil portion can be easily formed by, for example, pulling in the longitudinal direction the coil portion densely helically wound as the heating coil portion. .

When the outer diameter of the leg coil portion is less than 3.0 mm, the torsional stress increases, and the coil may be locally thinned or disconnected. On the other hand, if the outer diameter of the leg coil portion exceeds 5.5 mm, the spring constant increases, vibration in the longitudinal direction cannot be suppressed, and there is a possibility that the filament breaks at a welding location or the coil displaces at the heating coil portion. There is. Further, when the leg coil portion is formed from a coil portion densely spiraled equivalently to the heating coil portion, the coil pitch is reduced (percent pitch is reduced), and as a result, the amount of heat generated in the leg coil portion is increased.
Therefore, the helical diameter of the leg coil portion is such that the outer diameter is 3.0 to 3.0.
It was 5.5 mm.

The inner diameter of the helical diameter of the heating coil portion and the leg coil portion is mainly determined by the wire diameter.

According to the present invention, since the outer diameter of the spiral diameter of the leg coil portion is 3.0 to 5.5 mm and the outer diameter of the spiral diameter of the heat generating coil portion is 6.0 to 7.0 mm, The heater is small enough to generate a sufficient amount of heat, and the thinning and disconnection of the filament, the displacement of the coil of the heating coil portion are prevented, and the leg coil portion is formed from the coil portion that is spiraled as densely as the heating coil portion. It is easily formed.

According to a third aspect of the present invention, in the tubular heater according to the first or second aspect, the coil lengths of the leg coil portions are different from each other.

The coil length refers to the length of the filament in the longitudinal direction.

According to the present invention, since the coil lengths of the leg coils formed at both ends of the heating coil portion of the filament are different from each other, the tubular heater can be moved in the longitudinal direction with respect to the irradiation objects having different irradiation widths. The heating coil portion can be appropriately positioned at the irradiation width of the irradiation target.

According to a fourth aspect of the present invention, there is provided a tubular heater according to any one of the first to third aspects, wherein the tubular heater is disposed inside the tubular heater, and the tubular heater is conveyed while pinching the object to be fixed. And a heat roller for applying heat from the toner to the toner.

According to the present invention, since the central axis of the tubular valve and the central axis of the filament are substantially coincident with each other and the tubular heater in which the displacement of the coil of the heating coil portion is unlikely to occur is provided, the heating coil is provided. The heat generation distribution of the part is substantially uniform. As a result, the temperature distribution on the outer surface of the heat roller is made substantially uniform, and heat is uniformly applied to the member to be fixed, so that the toner is fixed.

According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising:
Image forming means for forming a reversal image by adhering toner to the electrostatic latent image and transferring the reversal image to a fixing member to form a predetermined image; melting the toner adhering to the fixing member to form an image And a fixing device according to claim 4 for fixing.

The image forming apparatus includes all devices having a function of forming an image using toner. The image means a character, a figure, a code, a video, and the like. For example,
There are image forming apparatuses such as a copying machine, a printer, and a facsimile.

According to the present invention, there is provided an image forming apparatus capable of uniformly fixing an image on a fixing member, since the fixing device for fixing the toner uniformly on the fixing member is provided.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described.

FIG. 1 is a partially cutaway front view of a tubular heater according to a first embodiment of the present invention. In the figure, 1 is a tubular heater, 2 is a tubular valve, 3 is a cap, 4 is a connector,
5 is a filament.

The tubular bulb 2 is made of a columnar transparent or translucent quartz glass, and has both ends 2A and 2B open. This tubular valve 2 has, for example, a pipe inner diameter of 8 m.
m, tube outer diameter 10mm, wall thickness 1.0mm, total length 300mm
Is formed.

The caps 3, 3 provided at both ends 2A, 2B of the tubular valve 2 have heat resistance and electric insulation, and are made of, for example, stainless steel. The cap 3 has a cylindrical portion 6, a flange portion 7, and a through hole 8. The cylindrical portion 6 has an outer diameter of 7.7 mm and is formed smaller than the inner diameter of the tubular valve 2.
Is inserted inside. The flange portion 7 is formed integrally with the cylindrical portion 6 and is formed to be larger than the inner diameter of the tubular valve 2, and has an outer diameter of, for example, 10 mm. When the cylindrical portion 6 is inserted into the tubular valve 2, the flange portion 7 is locked on the end face of the tubular valve 2. The through-hole 8 is formed so as to penetrate the central part of the cylindrical part 6 and the flange part 7, and the plate-like connector 4
Is penetrated. In the through hole 8, the cap 3 is the tubular valve 2.
When disposed at both ends 2A and 2B of the tubular valve 2, the tubular valve 2 is formed so as to be on the same straight line as the central axis thereof. The long holes (length and width) of the through holes 8 are, for example, 0.5 mm and 1.7 mm, respectively.

The filament 5 is formed by spirally forming a high melting point nichrome wire and having a heating coil portion 9, leg coil portions 10, 11 and mounting coil portions 12, 12. Filament 5
Any material, such as a nichrome wire, may be used as long as it generates a large amount of heat and does not easily oxidize even at high temperatures.

The heating coil portion 9 forms the main heating portion of the tubular heater 1 and is formed by densely spiraling the filaments (filament diameter 0.5 mm) of the filament 5 at, for example, a 150% pitch. Outer diameter of 6.0-7.0mm
And is provided at the center of the filament 5. When the outer diameter is in the range of 6.0 to 7.0 mm, the tubular heater 1 can be downsized, and a sufficient amount of heat can be obtained from the heat generating coil portion 9.

The leg coil portions 10 and 11 are spirally formed at both ends of the heat generating coil portion 10 at a pitch of, for example, 1000% so as to be relatively sparse relative to the density.
The outer diameter of the helical diameter is 3.0 to 5.5 mm, and the inner diameter is 2.0 to
It is formed to be 4.5 mm. That is, since the leg coil portions 10 and 11 are formed smaller than the outer diameter of the helical diameter of the heat generating coil portion 6.0 to 6.0 to 7.0 mm, and the filaments 5 are sparsely spiraled at a pitch of, for example, 1000%. Very low calorific value. Therefore,
Various support members disposed at both ends of the tubular valve 2 are prevented from being thermally damaged. The coil lengths L1 and L2 of the leg coil units 10 and 11 are different from each other, and are longer than the coil length L1 of the leg coil unit 10.
Is made longer.

The mounting coil sections 12, 12 are formed in a tight spiral at one end of the leg coil sections 10, 11, and the spiral diameter and the percent pitch are formed to be equal to those of the heating coil section 9. However, since the number of spiral wires is very small, the amount of heat generated from the mounting coil portions 12 is extremely small. The filament 5 is arranged in the longitudinal direction in the tubular valve 2 with the mounting coil portions 12, 12 connected to the connectors 4, 4.

The heating coil portion 9 may be provided with a leg coil portion or a jump portion in the middle in order to obtain substantially uniform heat radiation along the longitudinal direction of the tubular bulb 2. The jump portion is formed by, for example, forming a filament of the filament 5 on a substantially straight line.

The connector 4 is formed in a plate shape having a width of 1.5 mm and a thickness of 0.3 mm, for example.
b. The straight portion 4a is inserted into the through hole 8 from the cylindrical portion 6 side of the cap 3 and penetrates the through hole 8. Step 4
b is formed so as to have a step 4c which is bent from one end of the linear portion 4a and inscribed in the mounting coil portion 12 of the filament 5. The step 4c also functions as a stopper that comes into contact with the cylindrical portion 6 of the cap 3 when the straight portion 4a is inserted into the through hole 8. And step part 4
In (b), the mounting coil portion 12 of the filament 5 is welded, and the filament 5 and the connector 4 are electrically connected. At this time, it is preferable that a plurality of strands of the mounting coil portion 12 are welded to the step portion 4b. Thereby, the connection between the filament 5 and the connector 4 becomes strong, and the filament 5 is prevented from coming off the connector 4 due to impact, vibration, or the like.

Thus, the tubular heater 1 is configured. The tubular heater 1 is disposed, for example, inside a heat roller of a fixing device described later. In addition, the tubular heater 1 is
The total length varies depending on the heater power. In this case, the length of the heating coil portion 9 of the filament 5 and the like are appropriately adjusted.

In this embodiment, the flange 7 of the cap 3
A through hole 8 penetrating the cylindrical portion 6 and a cutout communicating with the outside are provided, and the connector 4 inserted into the through hole 8 of the cylindrical portion 6 is bent out of the cutout and led out to the outside. May be. That is, the through hole 8 may be formed in the cylindrical portion 6.

The through-hole 8 does not need to be provided at the center of the cylindrical portion 6. At this time, the step 4c of the connector 4 may be appropriately set so that the step 4b of the connector 4 is inscribed in the mounting coil portion 12 of the filament 5. Further, the step 4c may be appropriately set according to the inner diameter of the helical diameter of the mounting coil portions 12, 12.

Next, the operation of the first embodiment will be described.

The tubular heater 1 has a stepped portion 4 of the connectors 4 and 4.
b, 4b are formed so as to be inscribed in the mounting coil portions 12, 12 of the filament 5. And the mounting coil part 1
Two or twelve strands are welded at the steps 4b, 4b. And a filament 5 connecting the connectors 4 and 4
Is inserted through an opening at one end 2A or the other end 2B of the tubular valve 2. Then, at one end 2A of the tubular valve 2,
The cylindrical portion 6 is inserted into the tubular valve 2 while passing the straight portion 4a of the connector 4 through the through hole 8 of the cap 3, and the flange portion 7
Is locked to one end 2A, and the cap 3 is disposed at one end 2A of the tubular valve 2. Then, one end 2 of the tubular valve 2
In B, similarly, the cap 3 is disposed at one end 2B of the tubular valve 2. Thus, the tubular heater 1 is assembled.

The step portions 4b, 4b of the connectors 4, 4 are formed so as to be inscribed in the mounting coil portions 12, 12 of the filament 5, and in the step portions 4b, 4b, the mounting coil portions 12, 1 are formed.
2 is welded, so that the center axis of the filament 5 and the center axis of the tubular valve 2 substantially coincide. Therefore,
The mounting coil portions 12, 12 of the filament 5 are connected to the step portions 4b,
Since the center axis of the filament 5 and the center axis of the tubular valve 2 can be disposed substantially by simply welding to the connection 4b, the work of attaching the filament 5 to the connectors 4, 4 is easy. Also, the mounting coil portions 12, 1 of the filament 5
2 are welded at the step portions 4b, 4b, so that the connection between the connectors 4, 4 and the filament 5 becomes strong, and even if stress is applied to the welded portion due to pulling, impact, vibration or the like. , The filament 5 is the step 4 of the connector 4
b, 4b and disconnection at the steps 4b, 4b are prevented.

Since the caps 3, 3 are not fixed to the two ends 2A, 2B of the tubular valve 2, impacts, vibrations, etc. are likely to be applied to the filament 5 during carrying or the like. Also, the straight portions 4a, 4a or the caps 3 of the connectors 4, 4 are easily pulled in the longitudinal direction of the tubular valve 2,
The filament 5 is also pulled in the longitudinal direction. When the tension is released, the filament 5 vibrates in the longitudinal direction. However, the filament 5 is sparsely spiraled at both ends of the heating coil portion 9 and the leg coil portions 11 and 12 having a spiral diameter smaller than the spiral diameter of the heating coil portion 9.
Therefore, the vibration and the like are suppressed by the leg coil portions 11 and 12. As a result, stress applied to the welding portion between the step portion 4b of the connector 4 and the mounting coil portion 12 is small, and disconnection of the filament 5 at the welding portion is prevented. In addition, since the vibration and the like in the longitudinal direction of the heating coil unit 9 are reduced, the displacement of the coil of the heating coil unit 9 is prevented. Therefore, the heat generation distribution on the outer surface of the tubular valve 2 facing the heat generating coil portion 9 can be made substantially uniform.

The filament 5 is connected to the heating coil 9
The coil lengths L1 and L2 of the leg coil portions 11 and 12 formed at both ends are different from each other. Normally, the transfer position of the irradiation target is fixed, so that the tubular heater 1 can be moved in the longitudinal direction and the heating coil portion 9 can be appropriately positioned at the irradiation width of the irradiation target. At this time, since the leg coil portions 11 and 12 are sparsely spiraled and generate a very small amount of heat, heat irradiation to unnecessary portions of the irradiation target is minimized.

The leg coil portion 1 of the filament 5
1, 12 are, for example, 1000 less densely than the heat generating coil unit 9.
It is spiraled at a percent pitch, the spiral diameter is formed smaller than the spiral diameter of the heating coil part 9, and the outer diameter is 3.0 to 3.0.
It is set to 5.5 mm. Leg coil part 11,
When the outer diameter of the wire 12 is 3.0 mm or more, the torsional stress can be suppressed, and the wire diameter can be prevented from being locally reduced, and the filament 5 can be prevented from being broken. On the other hand, when the outer diameter of the leg coil portions 11 and 12 is 5.5 mm or less,
Since the spring constant is not increased, the filament 5 has rigidity, and vibrations and the like occur in the filament 5, and even if the heating coil portion 9 attempts to vibrate in the longitudinal direction, the vibrations and the like are suppressed. As a result, disconnection of the filament 5 at the welding location and displacement of the coil in the heating coil portion 9 can be prevented.

The leg coil portions 11 and 12 are formed, for example, while increasing the coil pitch of a coil portion that is spirally densely formed in the same way as the heating coil portions 9 formed at both ends of the heating coil portion 9.
The spiral diameter can be formed within the above numerical values. That is, the leg coil portions 11 and 12 can be easily formed.

Note that the coil lengths L1 and L2 of the leg coil portions 11 and 12 need not necessarily be different. Further, the heating coil unit 9 and the leg coil units 11, 1
The spiral diameter of 2 is effective if it is the above numerical value, but is not necessarily limited to the above numerical value.

The tubular heater 1 has a straight portion 4 of the connectors 4 and 4.
When a voltage is applied between a and 4a, the filament 5 is energized. Then, the heating coil section 9 of the filament 5 generates heat (infrared rays) and radiates the generated heat in all directions. Most of the generated heat is immediately emitted from the outer surface of the tubular bulb 2 and is irradiated on the irradiation target.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a schematic sectional view of a main part of a fixing device according to a second embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

A fixing device 13 shown in FIG. 2 shows a main part of a toner fixing device mounted on a copying machine, for example. In the drawing, 1 is a tubular heater, 14 and 14 are heat rollers, and 15 is a cover. The fixing member 16 is a toner.

The tubular heater 1 has a structure shown in FIG.
Inside the heat rollers 14, 14, they are arranged on a substantially central axis thereof via a support member (not shown).
The heat rollers 14, 14 are long rollers arranged to face each other up and down, and a silicone rubber or Teflon (registered trademark) is formed on the surface of a tubular body 17 made of aluminum or iron.
And the like. Then, the heat rollers 14 have a pressure contact relationship with each other,
By being rotated by a driving device (not shown) in the direction of the arrow shown in the drawing, the fixing member 15 is conveyed while being pinched, and heat from the tubular heater 1 is applied to the toner 16 adhered to the fixing member 15 and forming an image. Let it work. That is, the fixing member 15 and the toner 16 are heated from above and below by the heat rollers 14, 14, and the fused toner 16 a is fixed on the fixing member 15.

The tubular heater 1 has one heat roller 14 depending on the heating temperature for heating the member 15 to be fixed.
It may be arranged only in. The outer diameter of the heat rollers 14, 14 is 15 to 50 mm, and the thickness of the coating 18 is 0.2 to 3 m, depending on the size of the fixing member 15 and the heating temperature.
m, the electric power of the tubular heater 1 is appropriately set to 300 to 1200 W.

The tubular heaters 1, 1 disposed inside the heat rollers 14, 14 are disposed such that the central axis of the tubular valve 2 and the central axis of the filament 5 substantially coincide with each other. Since the displacement of the coil is unlikely to occur, the heat generation distribution of the tubular valve 2 facing the heating coil portion 9 becomes substantially uniform. As a result, the temperature distribution on the outer surfaces of the heat rollers 14 and 14 is made substantially uniform, heat is uniformly applied to the fixing member 15, and the fixing device 13 on which the toner 16 is fixed can be provided.

Next, a third embodiment of the present invention will be described.

FIG. 3 is a conceptual diagram of an image forming apparatus showing a third embodiment of the present invention. The same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

An image forming apparatus 19 shown in FIG. 3 is a copying machine, in which 20 is a reading device, 21 is an image forming means,
13, a fixing device; and 22, an image forming apparatus main body.

The reading device 20 optically reads a base paper to form an image signal. The image forming unit 21 forms an electrostatic latent image on the photosensitive drum 23 based on the image signal,
A toner 16 is adhered to the electrostatic latent image to form a reverse image, which is transferred to a fixing member 15 such as paper to form an image. The fixing device 13 has a structure shown in FIG. 2, and fixes the toner 16 adhered to the fixing target 15 by heating and melting. The image forming apparatus main body 22 includes the reading device 2 described above.
0, accommodating the image forming means 21 and the fixing device 13, and includes a transport device, a power supply device, a control device, and the like.

Since the image forming apparatus 19 includes the fixing device 13 for uniformly fixing the toner 16 on the fixing member 15, the image fixing on the fixing member 15 can be performed uniformly.

[0065]

According to the first aspect of the present invention, since the step portion of the connector is formed so as to be inscribed in the mounting coil portion of the filament, the filament can be easily welded to the step portion. The central axis of the tubular valve can be substantially aligned with the central axis of the filament. Further, even if vibration or the like due to tension or impact is applied to the filament, the leg coil suppresses vibration or the like, so that it is possible to prevent the filament from being broken at a welded portion and the displacement of the coil at the heating coil.

According to the invention of claim 2, the outer diameter of the helical diameter of the leg coil portion is 3.0 to 5.5 mm, and the outer diameter of the helical diameter of the heating coil portion is 6.0 to 7.0 mm. As a result, a sufficient amount of heat can be obtained by reducing the size of the tubular heater, and it is possible to prevent the filament from being thinned or broken, to prevent the coil from being displaced in the heating coil portion, and to achieve the same density as the heating coil portion. The leg coil portion can be easily formed from the coil portion spirally wound.

According to the third aspect of the present invention, since the coil lengths of the leg coils formed at both ends of the heating coil portion of the filament are different from each other, the tubular heater can be moved in the longitudinal direction, and the heating coil portion can be moved to the irradiation object. Can be appropriately positioned within the irradiation width.

According to the fourth aspect of the present invention, the fixing device is provided with a tubular heater in which the central axis of the tubular valve and the central axis of the filament substantially coincide with each other, and the displacement of the coil of the heat generating coil portion is less likely to occur. As a result, the temperature distribution on the outer surface of the heat roller is substantially uniform, and the heat can be uniformly applied to the fixing member to fix the toner.

According to the fifth aspect of the present invention, since the fixing device for uniformly fixing the toner on the fixing member is provided, it is possible to provide an image forming apparatus capable of uniformly fixing the image on the fixing member. .

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a tubular heater according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a main part of a fixing device according to a second embodiment of the present invention.

FIG. 3 is a conceptual diagram of an image forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a fixing device according to Prior Art 1.

FIG. 5 is a cross-sectional view of a tubular heater according to Prior Art 2;
(A) is a front view, (b) is a top view of a main part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tubular heater 2 ... Tubular valve 3 ... Cap 4 ... Connector 5 ... Filament 13 ... Fixing device 14 ... Heat roller 19 ... Image forming device 21 ... Image forming means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H033 AA03 AA23 BB18 BB21 3K058 AA22 AA45 AA86 BA18 CA05 CA12 CA23 CE02 CE12 CE17 DA02 GA06 3K092 PP18 QA02 QB02 QB27 QC42 QC51 RC16 RD11 TT11 TT36 VV22V28V28V

Claims (5)

[Claims] A tubular valve having both ends open; a cylindrical portion formed smaller than the inner diameter of the tubular valve; a cylindrical portion formed integrally with the cylindrical portion and formed larger than the inner diameter of the tubular valve. It has a flange portion to be engaged with the tubular valve and a through-hole penetrating the cylindrical portion, and has an electrically insulating property disposed at both ends of the tubular valve such that the cylindrical portion is inserted into the inside of the tubular valve. A cap; a densely spiraled heating coil portion, which is sparsely spirally wound at both ends of the heating coil portion, and which has a spiral diameter smaller than the spiral diameter of the heating coil portion, and a tightly closed end at one end of each leg coil portion. A filament having a spirally mounted coil portion and disposed in a longitudinal direction in the tubular valve; a linear portion penetrating through a through hole of the cap; and a filament mounting portion bent from one end of the linear portion. A connector having a step formed so as to be inscribed in the coil section, and a connector in which a filament mounting coil section is welded to the step and electrically connected thereto. . 2. The helical diameter of the leg coil portion of the filament has an outer diameter of 3.0 to 5.5 mm, and the helical diameter of the heating coil portion has an outer diameter of 6.0 to 7.0 mm. The tubular heater according to claim 1, wherein 3. The coil length of each leg coil section is:
The tubular heater according to claim 1, wherein the heaters are different from each other. 4. A tubular heater according to claim 1, wherein the tubular heater is disposed inside, and a heat roller which conveys the object to be fixed while pinching it and applies heat from the tubular heater to the toner. And a fixing device. 5. An image forming means for forming a reverse image by adhering toner to an electrostatic latent image and transferring the reverse image to a fixing member to form a predetermined image; An image forming apparatus comprising: the fixing device according to claim 4, wherein the fixing is performed by melting the image.