JPH0996983A - Fixing heater, fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service life by means of reducing the wear, and to make the setting of heating temp. easy and the workability excellent. SOLUTION: This device is provided with a roller base body 12 composed in a cylindrical shape or columnar shape heat resistant electrically insulated material, a resistance heater 13 composed at least on a periphery of the roller base body 12, and a pair of annular electrodes 14a and 14b coaxially composed at least on the periphery of the roller base body 12 while electrically connected to the resistance heater 13. Then, the device is provided with non-circular elliptic holes 16a and 16b coaxially disposed so as to recess on both ends in the shaft direction of respective annular electrodes 14a and 14b, receiving plugs 17a and 17b electrically connected while fitted in the respective elliptic holes 16a and 16b, and rotary shaft 18a and 18b disposed so as to project in a state composed coaxially in the respective receiving plugs 17a and 17b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller-type fixing heater suitable for use in small equipment such as office automation equipment, household electric equipment and precision manufacturing equipment, and a copying machine equipped with this fixing heater. The present invention relates to a fixing device used for fixing a toner such as a facsimile and an image forming apparatus using the fixing device.

[0002]

2. Description of the Related Art Generally, in an electronic copying machine, a copy sheet on which a toner image is formed is passed between a fixing heater and a pressure roller while directly or indirectly through a heat-resistant sheet while pressing the fixing sheet. It is equipped with a fixing device that heats, melts, and fixes the toner on the copy paper by the heating of.

As a conventional fixing device of this type, for example, a roller type fixing device constructed as shown in FIGS. 14 and 15 has been put into practical use. The roller-type fixing heater 1 has a pair of left and right annular electrodes 2a and 2b in the figure, and elastically slidably supports curved tip portions of a pair of power feeding brushes 3a and 3b made of strip-shaped leaf springs made of phosphor bronze or the like. The resistance heating element 5 formed on the outer surface of the roller base 4 is energized and heated by being pressed against and feeding power to the annular electrodes 2a and 2b from the power feeding brushes 3a and 3b.

The fixing heater 1 has a resistance heating element 5 formed on at least the outer surface of the roller base 4 formed in a cylindrical shape from a heat-resistant electric insulating material such as ceramics, and both ends of the resistance heating element 5 in the axial direction. At the pair of annular electrodes 2
The a and 2b are integrally or integrally formed by, for example, pattern printing of an Ag-based good conductor paste, and are in contact with and electrically connected to the resistance heating element 5 over substantially the entire circumference.

Since the roller base body 4 of the roller type fixing heater 1 is not provided with a rotary shaft, the pressure roller 6 (not shown) is lightly elasticated over substantially the entire length of the roller base body 4 as shown in FIG. Are circumscribed externally and face each other, and are rotatably held by a pair of left and right small rollers 7a and 7b installed on the opposite side, and the fixing heater 1 is rotated by the rotation of the pressure roller 6, and The copy sheet P on which the toner image is formed, which is supplied between the rollers 1 and 6, is heated while pinching it to fix the toner image on the copy sheet P.

[0006]

However, in such a conventional roller-type fixing heater 1, the pair of annular electrodes 2 is used.
Since a and 2b are formed by pattern printing and firing of Ag-based good conductor paste, the power feeding brushes 3a and 3b
It is easily worn by sliding b and has a short life.

Further, since the feeding brushes 3a and 3b are slidably brought into contact with the outer peripheral surfaces of the respective annular electrodes 2a and 2b having the highest rotation speed, the abrasion of the respective annular electrodes 2a and 2b is further large and fast. . Therefore, there is a problem that the life is short.

Further, as shown by the broken line in FIG. 14, a pair of power feeding brushes 3 sliding on the pair of annular electrodes 2a, 2b.
Since both the sliding portions a and 3b are arranged substantially coaxially, current flows in the resistance heating element 5 in a concentrated manner at the portion indicated by the broken line in the figure.

For this reason, the amount of heat generated by the resistance heating element 5 in the vicinity of the broken line becomes larger than the others, so that the temperature distribution in the circumferential direction becomes uneven, and it is not easy to set the heating temperature of the resistance heating element 5. There is a problem that there is no.

Further, since the roller base body 4 is not provided with a rotary shaft, the roller base body 4 must be rotatably sandwiched between the pressure roller 6 and the pair of left and right small rollers 7a and 7b, resulting in a complicated structure. In addition, there is a problem that the number of parts increases, assembly workability of the fixing heater 1 deteriorates, and cost increases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fixing heater, a fixing device, and an image forming apparatus which have less wear due to an annular electrode, have a long life, and can easily set a heating temperature of a resistance heating element and have good assembling workability. To provide.

[0012]

According to the invention of claim 1, a base body formed of a heat-resistant electric insulating material in a cylindrical or columnar shape; a resistance heating element formed on at least an outer surface of the base body; A pair of electrodes concentrically formed on the outer surface and electrically connected to the resistance heating element; -a conductive metal body detachably attached to the pair of electrodes and electrically connected thereto; A pair of power receiving portions having a pair of conductive shafts that are coaxially projectingly provided so as to project outward in the axial direction on the outer surface of the main body; and each power receiving portion and each electrode around the central axis of one of these. And a locking portion that locks in a disengageable manner so as to prevent idling against rotation.

Therefore, according to the present invention, the power receiving portion can be easily provided by simply attaching the power receiving portion to the pair of electrodes of the roller base detachably, and at the same time, the shaft of the power receiving portion can be attached to the roller base. Can be used as a rotating shaft. Therefore, unlike the conventional example, it is not necessary to have a complicated structure in which the roller base is rotatably supported by the pressure roller and the pair of small rollers, and the pair of small rollers can be omitted to reduce the number of parts and the structure. It is possible to achieve simplification together.

Further, since each power receiving portion and each electrode are locked by the locking portion so as not to run idle, it is possible to prevent the power receiving portion from spinning due to the rotation of the roller base and the electrode.

The locking portion means a contact portion when the roller base and the power receiving portion are simply fixed by friction between them.

Therefore, it is possible to effectively prevent only a part of the resistance heating element from being energized and heated due to the idling of the power receiving portion to cause uneven heating, and thus uneven fixing.

The invention according to claim 2 is the invention according to claim 1, further, in each power receiving portion, the outer surface of the main body made of a conductive metal is covered with an electric insulator.

Therefore, according to the present invention, it is possible to stabilize electrical characteristics such as preventing a short circuit between the conductive metal main body and other conductors, and to improve safety.

The third aspect of the present invention is the first or second aspect.
In the invention described above, the engaging portion is configured such that the fitting portion between the electrode and the power receiving portion has a non-circular cross-sectional shape.

Therefore, according to the present invention, the same effect as that of the first aspect of the invention can be obtained, and the power receiving portion can be simply, quickly and surely formed by simply fitting the power receiving portions to the respective electrodes. Therefore, the workability of assembling the fixing heater can be improved.

The invention according to claim 4 is the invention according to claim 3, wherein the engaging portion is provided with a non-circular center hole in the axial end surface of the electrode, and the engagement portion is fitted into the center hole to cause electrical connection. The power receiving portion is formed with a fitting portion that is electrically connected.

Therefore, according to the present invention, in addition to the same effect as the invention described in claim 3, the roller base body is formed by simply fitting the fitting portion of the power receiving portion into the non-circular center hole of the electrode. The power receiving unit can be provided so as not to run idle, and at the same time, the rotating shaft can be provided.

The invention according to claim 5 is the invention according to claim 3, wherein the engaging portion is formed by concentrically projecting a non-circular projection on an axial end surface of the electrode, and the projection is provided with an outer surface. A conductive metal cap that is fitted and electrically connected is configured as a power receiving unit.

Therefore, according to the present invention, in addition to the same effects as the third aspect of the invention, the roller is formed by simply inserting the conductive metal cap of the power receiving portion into the non-circular center hole of the electrode. The base body can be provided with the power receiving unit so as not to run idle, and at the same time, the rotary shaft can be provided.

The invention according to claim 6 is the invention according to claim 1 or 2.
In the invention described above, the locking portion has a locking concave portion formed on one of the power receiving portion and the electrode, and a locking convex portion which is removably engaged with the concave portion is provided on the other of the power receiving portion and the electrode. It becomes.

Therefore, according to the present invention, in addition to the same effect as that of the invention described in claim 1 or 2, the locking concave portion of one of the electrode and the power receiving portion is simply fitted into the locking concave portion of the other. By doing so, the power receiving portion can be provided on the roller base body so as not to idle, and at the same time, the rotating shaft can be provided.

According to a seventh aspect of the present invention, a base body formed of a heat-resistant electric insulating material in a cylindrical or columnar shape; a resistance heating element formed on at least the outer surface of the base body; concentric with at least the outer surface of the base body A pair of electrodes that are formed in a shape and are electrically connected to the resistance heating element; a metal cap body that is tightly fitted and electrically connected to the outer surface of each electrode, and an outer end surface of each cap body. , A shaft that is provided coaxially so as to project outward in the axial direction, an electrically conductive power receiving portion that is formed in a ring shape on the outer peripheral surface of the metal cap body, and a ring shape on both sides of this power receiving portion. And a metal cap having an electrically insulating portion.

The invention as defined in claim 8 is defined by claim 1 through claim 7.
The fixing heater is provided with a pair of power supply members that slidably contact the respective shafts and supply power.

The invention according to claim 9 is the invention according to claims 1 to 7.
Any one of the fixing heaters described above is provided with a pair of power supply members that slidably contact the central portions of the outer end surfaces of the respective caps to supply power.

Therefore, according to the eighth and ninth aspects of the invention, the resistance heating element of the rotating roller base can be energized and heated from the power feeding element through the metal power receiving portion and the electrode. Moreover, since the power receiving portion is made of metal, it is less likely to wear due to sliding with the power supply body, and the fixing heater can be supported by the power supply body, so that the service life can be extended.

According to a tenth aspect of the present invention, there is provided the fixing device according to the eighth or ninth aspect; a conveying sheet that can travel in a direction intersecting the longitudinal direction of the fixing heater; A pressure roller which is arranged so as to press the fixing heater and causes heat from the fixing heater to act on the toner forming the image of the fixing target via the conveying sheet and conveys the fixing target. It has.

According to an eleventh aspect of the present invention, there is provided the fixing device according to the tenth aspect, wherein toner is attached to the electrostatic latent image formed on the medium to form a reverse image, and the reverse image is transferred to the fixing target. And means for forming a predetermined image.

Therefore, the fixing device according to claim 10,
The image forming apparatus according to claim 11 has the respective inventions described above, and therefore has substantially the same operational effect.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
~ It demonstrates based on FIG. In addition, in FIGS.
The same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a partially exploded perspective view of a fixing heater according to a first embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of the right end portion of FIG. 1, in which fixing heater 11 is heat resistant. An electrically insulating material such as alumina (Al ₂ O ₃ ) or mullite (3Al ₂ O ₃ .2SiO ₂ ) ceramic is used to form a roller body 12 in the form of a straight cylinder, for example, into a roller type so that it can be rotatably supported. I am configuring.

The roller base 12 is, for example, silver / palladium (A
A film-shaped resistance heating element 13 mainly composed of a g.Pd) alloy, a nickel-tin (Ni.Sn) alloy, or the like is formed in an annular band shape by thick film printing or the like.

Further, the roller base 12 is formed on the outer peripheral surface at both ends in the axial direction of the ring made of a good conductor film such as silver or silver / platinum (Ag / Pd) alloy, silver / palladium alloy (Ag / Ρd). A pair of right and left strip-shaped electrodes 14a and 14b are formed by thick film printing.
Each of the inner end portions 14a1 and 14b1 partially overlaps with both end portions 13a and 13b of the resistance heating element 13 in the vertical direction, for example, and is electrically connected to each other over the entire circumference to supply power to the resistance heating element 12. It is supposed to do.

As shown in FIG. 2, the electrodes 14a and 14b are integrally connected to both axial ends of the roller base 12 and the inner peripheral side thereof. The entire outer peripheral surface of the resistance heating element 12 is entirely covered with a glassy overcoat layer 15,
Improvements in mechanical strength such as abrasion resistance and impact resistance, protection against corrosion from sulfidation and oxidation, and electrical insulation from pressure rollers and the like have been achieved. However, as shown in FIG. 3 (A), the overcoat layer 15 may be omitted, and as shown in FIG. 3 (B), the outer peripheral surface of the metal pipe 12a is entirely coated with the ceramics layer 12b. Alternatively, the roller base 12 may be configured as follows.

Then, as shown in FIGS. 1 and 4 (A), elliptical holes 16a, 16b, which are non-circular center holes, are concentrically formed at both axial ends of the pair of annular electrodes 14a, 14b. As shown in FIG. 2, parts of the electrodes 14a and 14b are integrally connected to the inner peripheral surfaces of the elliptical holes 16a and 16b.

In the elliptical holes 16a and 16b, as shown in FIG.
A pair of elliptical plate-shaped power receiving plugs 17a and 17b made of a conductive metal, which are also shown by (B), are closely fitted. The power receiving plugs 17a and 17b are received by the inward flanges 12c formed inwardly at both ends of the roller base 12. Each elliptical hole 1
The joint surfaces between the power receiving plugs 6a and 16b and the respective power receiving plugs 17a and 17b may be fixed to each other by an adhesive agent, welding or the like (not shown). Each of the power receiving plugs 17a and 17b is made of, for example, a copper-based conductor or a conductor such as a copper-based conductor plated with silver, and has a small-diameter short-shaft rotating shaft having conductivity and wear resistance at the center of its outer end surface. 18a and 18b are integrally and concentrically provided so as to project outward in the vertical direction. In addition, each power receiving plug 17
The outer surfaces of a and 17b may be covered with an electric insulator. According to this, it is possible to prevent the power receiving plugs 17a and 17b from being short-circuited with other conductors, stabilize the electric characteristics, and enhance the safety.

On the pair of rotating shafts 18a and 18b of the fixing heater 11 constructed as described above, as shown in FIG. 5, a phosphor bronze plate or a conductive strip-shaped spring material made of copper or copper plated with silver is used. The pair of power supply brushes 19a and 19b are elastically brought into contact with each other and slid on the outer surfaces of the curved tips, and are electrically connected.

A power supply circuit (not shown) is electrically connected to the pair of power supply brushes 19a and 19b, and the power supply brushes 19a and 19b are connected to the rotary shafts 18a and 18b through the terminals and the power receiving plugs 17a and 17b. Electrodes 14a, 14b
Power is supplied to the resistance heating element 12 to electrically heat it. The free tips of the rotary shafts 18a and 18b may be rotatably supported by electrically insulating bearings (not shown).

Therefore, according to an embodiment of the present invention,
-By simply inserting the power receiving plugs 17a and 17b into the elliptical holes 16a and 16b of the pair of electrodes 14a and 14b,
The power receiving portion can be easily provided, and at the same time, the rotary shafts 18a and 18b of the power receiving plugs 17a and 17b can be used as the rotary shafts of the roller base 12. Therefore, unlike the conventional example shown in FIG. 16, it is not necessary to have a complicated structure in which the fixing heater 1 is rotatably sandwiched between the pressure roller 6 and the pair of small rollers 7a and 7b. , 7b can be omitted to reduce the number of parts and simplify the configuration.

Further, since the power receiving plugs 17a, 17b and the elliptical holes 16a, 16b of the electrodes 14a, 14b are non-circular, the power receiving plugs 17a, 17b run idle by the rotation of the roller base 12 and the electrodes 14a, 14b. Can be prevented.

Therefore, it is possible to effectively prevent uneven heating due to uneven heating caused by partial heating of the resistance heating element 13 due to idling of the power receiving portion as in the conventional example.

Further, even when the roller base 12 is rotated, the pair of power supply brushes 19a, 19b are moved from the pair of rotary shafts 1 to each other.
It is possible to reliably supply power to the resistance heating element 13 through the 8a, 18b and the power receiving plugs 17a, 17b, and the paired annular electrodes 14a, 14b in order to electrically heat them.

Since the pair of rotary shafts 18a and 18b have a diameter smaller than that of the roller base body 12 and are arranged at the shaft center portion of the roller base body 12 having the slowest rotation speed, the rotary shafts 18a and 18b are Power supply brush 19 that slidably contacts
The speed of the sliding portions of a and 19b can be reduced. Further, since the rotary shafts 18a and 18b have wear resistance,
The wear of the power supply brushes 19a, 19b and the rotary shafts 18a, 18b can be reduced, so that the service life can be extended.

FIG. 6 is a perspective view of a fixing heater 11A according to a second embodiment of the present invention, and FIG. 7 is a side view thereof. The fixing heater 11A is located laterally of a pair of rotating shafts 18a and 18b (see FIG. 6 and 7), a pair of power feeding brushes 19a,
The arcuate curved end of 19b is connected to each of the power receiving plugs 17a, 17
The roller base body 1 is elastically pressed directly against the side end surface of b to form the roller base body 1.
Each power receiving plug 1 receives the required power while sliding when rotating 2
The feature is that power is supplied to 7a and 17b.

In each of the above embodiments, each electrode 14a, 1
Although the case where the elliptical holes 16a and 16b are bored in 4b has been described, the present invention is not limited to this, and any non-circular or central hole having a locking portion may be used, for example, as shown in FIG. As shown in FIG. 1, one small circular arc hole 16d may be integrated into one circular hole 16c as a locking hole, and the speed may be integrated.
Furthermore, as shown in FIG. 8 (B), one circular hole 16
Two small circular arc holes 16d may be integrally connected to c at positions that face each other in the diametrical direction.

Further, the elliptical holes 16a and 16b are formed as shown in FIG.
It may be replaced with a triangular hole 16e shown in (A), a square hole 16f shown in FIG. 9 (B), or a non-circular hole such as a pentagonal or larger polygon (not shown). In this case, it is needless to say that the shape of each of the power receiving plugs 17a and 17b is a shape such as a triangle 17c or a quadrangle 17d that can be tightly fitted into these non-circular holes as shown in FIGS. 9 (A) and 9 (B). Is.

FIG. 10 shows an example of the third embodiment of the present invention. This fixing heater 11B has the elliptical holes 16 described above.
a and 16b are replaced with elliptical projections 21a and 21b, respectively, and the elliptical power receiving plugs 17a and 17b are replaced by elliptic cylindrical power receiving caps 22a and 22 made of a conductive metal.
The feature is that they are replaced by b.

The elliptical protrusions 21a and 21b are formed of a conductor on the outer end faces of the annular electrodes 14a and 14b so as to be integral or integral with and concentric with them. Elliptic cylinder-shaped power receiving caps 22a and 22b made of a conductive metal are tightly fitted to the outer periphery of to electrically connect. This fitting joint surface may be fixed by an adhesive, welding, or the like. Each power receiving cap 22a, 22
In the central portion of the outer surface of the lid part b, conductive rotating shafts 23a and 23b having a small diameter and a short axis are concentrically provided so as to project outward in the vertical direction.

Therefore, also in this embodiment, since the elliptical projections 21a and 21b and the power receiving caps 22a and 22b fitted on the elliptical projections 21a and 21b are both formed in a non-circular shape, like the above embodiment, It is possible to easily and reliably prevent these from slipping.

Further, each of these elliptical protrusions 21a, 21b
The shape of each of the power receiving caps 22a and 22b may be replaced with a non-circular shape or a shape having a locking portion, as in the above embodiment. The outer surfaces of the power receiving caps 22a and 22b may be electrically insulated by being covered with an electrical insulator, which prevents short-circuiting with other conductors and stabilizes safety and electrical characteristics. And can work together.

FIG. 11 is a perspective view of an example of the fourth embodiment of the present invention. This fixing heater 11C has a pair of annular electrodes 14a and 14b, and a wear-resistant conductive metal cap 24.
a and 24b are externally fitted and fixed, and further, this metal cap 2
On the outer peripheral side surfaces of 4a and 24b, in the widthwise central portion,
Ring-shaped power receiving bands 25a and 25b are formed, and ring-shaped insulating bands 26a and 26b, 27a and 27b made of an electrically insulating coating or the like are formed on both sides of the power receiving bands 25a and 25b, and each metal cab 24a. , 24b on the outer end face,
It is characterized in that the rotary shafts 28a and 28b of small diameter and short shaft are provided in a protruding manner.

Therefore, each of these power receiving bands 25a, 25
b, for example, the power supply brushes 19a and 19b shown in FIG.
Elastically pressing the curved tip end of each of them to electrically connect them to each other from the feeding brushes 19a, 19b to the respective annular electrodes 14a, 14b.
Can be powered. Moreover, the metal cap 24
Since a and 24b have abrasion resistance, the power supply brushes 19a and
Long life can also be achieved by sliding with 19b.

FIG. 12 shows the construction of an embodiment of an electronic copying machine 31 which is a kind of the image forming apparatus of the present invention. The copying machine 31 has a casing 32 in which copying paper P in a cassette 33 is placed. An image forming unit 34 that pulls in and forms a toner image corresponding to an image of an original (not shown) and a fixing device 35 that fixes the toner image on the copy paper P are built-in.

The fixing device 35 is constructed, for example, as shown in FIG. 13, and faces the pressure roller 36, and any one of the fixing heaters 11, 11A, 11B and 11C, for example, 11
Are arranged side by side, and the rotation shaft 18a of the fixing heater 11 is
18b is rotatably supported by a bearing (not shown), and the outer peripheral surface of the fixing heater 11 is elastically pressed against the silicone rubber layer 37 of the pressure roller 36.

The fixing heater 11 is composed of a pair of rotating shafts 1.
The resistance heating element 13 is heated by the pair of elastic power supply brushes 19a, 19b made of a phosphor bronze plate or the like which are slidably contacted on the 8a, 18b to heat the overcoat layer 15. Therefore, the copy sheet P on which the toner image T has been formed is nipped between the outer surface of the surface glass coat layer 15 and the silicone rubber layer 37 of the pressure roller 36 and heated by the fixing heater 11, whereby the unfixed toner is unfixed. The image T can be melted and fixed on the copy paper P.

Further, the fixing heater 11 has a long life,
Since the roller base 12 and the power receiving plugs 17a and 17b can be prevented from idling and temperature unevenness can be effectively prevented,
The fixing device 35 and the electronic copying machine 31 have a long life and can prevent fixing unevenness.

[0061]

As described above, according to the first aspect of the invention of the present application, the power receiving portion can be easily provided by simply attaching the power receiving portion to the pair of electrodes of the roller base body in a detachable manner. The shaft of the power receiving unit can be used as the rotating shaft of the roller base. Therefore, unlike the conventional example, it is not necessary to take a complicated structure in which the roller base is rotatably supported by the pressure roller and the pair of small rollers,
By omitting the pair of small rollers, the number of parts can be reduced and the structure can be simplified.

Further, since each power receiving portion and each electrode are locked by the locking portion so as not to run idle, it is possible to prevent the power receiving portion from running idle due to the rotation of the roller base and the electrode.

Therefore, it is possible to effectively prevent uneven heating due to the partial heating of the resistance heating element due to the idling of the power receiving portion to cause uneven heating.

According to the second aspect of the present invention, it is possible to stabilize electrical characteristics such as preventing a short circuit between the conductive metal main body and another conductor, and to improve safety.

According to the invention described in claim 3, in addition to the same effect as the invention described in claim 1 or 2, the power receiving portion can be simply and quickly attached by simply fitting the power receiving portions to the respective electrodes. Since it can be reliably formed, the workability of assembling the fixing heater can be improved.

According to the invention described in claim 4, in addition to the same effect as the invention described in claim 3, by simply fitting the fitting portion of the power receiving portion into the non-circular center hole of the electrode, The roller base can be provided with the power receiving unit so as not to run idle, and at the same time, the rotary shaft can be provided.

According to the invention described in claim 5, in addition to the same effect as the invention described in claim 3, the conductive metal cap of the power receiving portion is simply fitted into the non-circular center hole of the electrode. Thus, the power receiving portion can be provided on the roller base body so as not to run idle, and at the same time, the rotating shaft can be provided.

According to the invention described in claim 6, in addition to the same effect as the invention described in claim 1 or 2, the locking recess of one of the electrode and the power receiving portion is simply provided in the locking projection of the other. By inserting the portion, the power receiving portion can be provided on the roller base body so as not to idle, and at the same time, the rotating shaft can be provided.

According to the seventh, eighth and ninth aspects of the present invention, the resistance heating element of the rotating roller base can be energized and heated from the power feeding element through the metallic power receiving portion and the electrode. Moreover, since the power receiving portion is made of metal, it is less likely to wear due to sliding with the power feeding body, and the life can be extended.

A fixing device according to claim 10 and claim 11
The described image forming apparatus has the above-described inventions as appropriate, and therefore has substantially the same operational effects.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view of a fixing heater according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a part of FIG.

3 is a sectional view taken along the line III-III in FIG. 1, and (B) is a sectional view of another example of the same (A).

4A is an end view of the annular electrode shown in FIG. 1, and FIG.
2 is an end view of the power receiving plug shown in FIG. 1. FIG.

FIG. 5 is a perspective view of a fixing heater according to a second embodiment of the present invention.

FIG. 6 is a perspective view of a fixing heater according to a third embodiment of the present invention.

FIG. 7 is a side view of FIG. 6;

8A and 8B are end views showing modified examples of the elliptical hole shown in FIG.

9A and 9B are end views showing modifications of the elliptical hole and the power receiving plug shown in FIG. 1, respectively.

FIG. 10 is a partially exploded perspective view of a fixing heater according to a fourth embodiment of the present invention.

FIG. 11 is a partially exploded perspective view of a fixing heater according to a fifth embodiment of the present invention.

FIG. 12 is an overall configuration diagram of an image forming apparatus according to a sixth embodiment of the present invention.

FIG. 13 is an enlarged configuration diagram of a main part of the fixing device shown in FIG.

FIG. 14 is a perspective view of a part of a conventional fixing heater.

FIG. 15 is a side view of the conventional fixing heater shown in FIG.

16 is a view showing a support structure of the conventional fixing heater shown in FIG.

[Explanation of symbols]

 11, 11A, 11B, 11C Fixing heater 12 Roller base 13 Resistance heating element 14a, 14b Pair of annular electrodes 15 Glass coat layers 16a, 16b Elliptical hole (non-circular center hole) 17a, 17b Power receiving plug 18a, 18b Rotating shaft 19a, 19b Power feeding brushes 21a, 21b Elliptical protrusions 22a, 22b Power receiving caps 23a, 23b Rotating shafts 24a, 24b Power receiving shafts (conductive shafts) 25a, 25b Annular conductive band 31 Electronic copying machine (image forming apparatus) 32 Housing 33 Cassette 34 Image Forming Section 35 Fixing Device 36 Pressure Roller 37 Silicone Rubber Layer P Copy Paper T Toner Image

Claims (11)

[Claims] 1. A substrate formed of a heat-resistant electric insulating material in a cylindrical or columnar shape; a resistance heating element formed on at least the outer surface of the substrate; and a resistance formed concentrically on at least the outer surface of the substrate. A pair of electrodes electrically connected to the heating element; a conductive metal body detachably attached to the pair of electrodes and electrically connected thereto, so that the body outer surface projects outward in the axial direction. A pair of power receiving portions having a pair of electrically conductive shafts that are coaxially projecting from each other; and each power receiving portion and each electrode are disengaged so as to prevent idling against rotation about one of these central axes. A fixing heater comprising: a locking portion that can be freely locked. 2. The fixing heater according to claim 1, wherein each of the power receiving units covers an outer surface of a conductive metal body with an electric insulator. 3. The fixing heater according to claim 1, wherein the engaging portion is configured so that a fitting portion between the electrode and the power receiving portion has a non-circular cross-sectional shape. 4. The engagement portion is formed by forming a non-circular center hole in the axial end surface of the electrode, and forming a fitting portion, which is fitted into the center hole and electrically connected, in the power receiving portion. The fixing heater according to claim 3, wherein 5. A non-circular projection is concentrically provided on the axial end surface of the electrode, and the engaging portion is provided with a conductive metal cap which is fitted onto the projection and electrically connected thereto. The fixing heater according to claim 3, wherein the fixing heater is configured as follows. 6. The locking portion is formed by forming a locking concave portion on one of the power receiving portion and the electrode, and providing a locking convex portion which is removably engaged with the concave portion on the other of the power receiving portion and the electrode. The fixing heater according to claim 1, wherein the fixing heater is a fixing heater. 7. A base formed of a heat-resistant electrical insulating material in a cylindrical or columnar shape; a resistance heating element formed on at least the outer surface of the base; and a resistance formed concentrically on at least the outer surface of the base. A pair of electrodes electrically connected to the heating element; a metal cap main body that is tightly fitted and electrically connected to the outer surface of each electrode and is electrically connected to the outer end surface of each cap main body in the axial direction. A coaxially protruding shaft, a conductive power receiving portion formed in a ring shape on the outer peripheral surface of the metal cap body, and an electric insulation portion formed in a ring shape on both sides of the power receiving portion. And a metal cap having: a fixing heater. 8. A fixing device, comprising a pair of power supply members that slidably contact the respective shafts of the fixing heater according to any one of claims 1 to 7 to supply power. 9. The fixing heater according to claim 1, further comprising a pair of power supply members that slidably contact the center portions of the outer end surfaces of the respective caps to supply power. Fixing device. 10. The fixing device according to claim 8 or 9,
A conveyance sheet that can travel in a direction intersecting the longitudinal direction of the fixing heater; a fixing sheet that is arranged to face the fixing heater through the conveyance sheet and presses the fixing heater, and from the fixing heater through the conveyance sheet. And a pressure roller that conveys the image to be fixed on the toner on the image to be fixed and conveys the image to be fixed. 11. The fixing device according to claim 10, wherein toner is attached to the electrostatic latent image formed on the medium to form a reverse image, and the reverse image is transferred to a fixing target to form a predetermined image. An image forming apparatus comprising: a forming unit;