JP2001117405A - Image forming device having heating fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device having heating fixing device with which a receiving member can be surely fixed on a surface heating fixing roller, further, conduction to a resisting heating element is secured, safety is improved and rise time is quickened. SOLUTION: The heating fixing device of the image forming device is provided with a fixing roller 10 and a feeding brush 15 for feeding power to the fixing roller 10, the fixing roller 10 is provided with a metal substrate 11 having a folded part 11b folding both ends to the inner peripheral sides, electric insulating layer 12 laminated on the inner surface of the metal substrate 11, resisting heating element 13 laminated on the electric insulating layer 12, and receiving electrode 14 connected to the folded part 13b of the resisting heating element 13, and the feeding brush 15 feeds power to the receiving electrode 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to an image forming apparatus having a heat fixing device using an electrophotographic process such as a facsimile and a printer.

[0002]

2. Description of the Related Art As a fixing method of a toner image in electrophotography, a heat fixing method, a pressure fixing method and a solvent fixing method are known. Among these fixing methods, the heat fixing method is such that the heated fixing roller is rotated, and the sheet on which the toner image has been transferred is nipped and conveyed by the rotating fixing roller and the pressing roller. It fuses and fuses on paper.

In recent years, due to environmental regulations and increasing awareness of environmental protection, various types of electrophotographic apparatuses have been designed to cut power supply to a fixing heater when not in use and to supply power only when necessary, thereby reducing power consumption. ing.

In such an energy-saving electrophotographic apparatus, it is required that the surface temperature of the fixing roller immediately reaches a set temperature at which printing can be performed during printing. One way to meet this requirement is to
There has been proposed a fixing device using a heating roller of a direct heating type having a heating element on an inner surface or an outer surface of the fixing roller.

A fixing device using a heat-generating fixing roller directly heats the fixing roller by heat conduction by a resistance heating element, which is about 20 to 30% of that of a radiant heating type fixing device using a halogen lamp. The rise time can be shortened. Moreover, the fact that no rush current is generated when the power is turned on, such as a radiation heating method using a halogen lamp, is also a major feature of the fixing device using the heat generating fixing roller.

In the case of a heat-fixing roller, one problem is how to supply power to a resistance heating element that is a heating source that rotates together with the roller. A method of supplying power to a rotating body is generally to supply power by sliding a conductive brush serving as a power supply electrode to a power receiving electrode provided on a roller serving as a rotating body. As an example, Japanese Patent Application Laid-Open No. H11-15317 discloses an example. Are known.

FIG. 6 shows a first conventional example of Japanese Patent Application Laid-Open No. 11-15 / 1999.
317 is a side cross-sectional view showing one configuration example of a fixing device using a heat-fixing roller system disclosed in Japanese Patent Publication No. 317. As shown in FIG. 6, a pressure roller 20 is pressed against the fixing roller 10 with a constant pressing force by a spring (not shown). Both ends of the fixing roller 10 are insulated bush 12
1. The fixing roller 10 is supported on the side plate 120 via a bearing 122. Further, a gear 123 is provided at one end of the fixing roller 10, and the fixing roller 10 is driven to rotate by engaging the gear 123 with a driving source (not shown). Fixing roller 10
Is a thin pipe-shaped metal substrate 111 made of aluminum or iron.
And the thickness of the metal substrate 111 is 0.3 to 2.0.
mm. On the outer surface of the metal substrate 111, a surface release layer 117 is formed, and on the inner surface of the metal substrate 111, an electric insulating layer 112 and a resistance heating element layer 113 are laminated.

As shown in FIGS. 7 and 8, cap-shaped power receiving electrode members 114 for supplying power are provided at both ends of the resistance heating element layer 113. As a result, the power supply electrode brush 115 as a power supply electrode member is pressed with a constant load, and the power reception electrode member 114 and the power supply electrode brush 115 are energized while sliding.

The resistance heating element layer 113 is made of stainless steel foil (thickness t = 10 to 100 μm) such as iron chromium, and is punched or etched, for example, as shown in FIG.
It is formed in a pattern as shown in (B) and (C), and is laminated inside the electric insulating layer 112 such as a polyimide film, aramid paper, or a mica sheet. The resistance heating element layer 113 is provided on the fixing roller 10 as shown in FIG.
May be formed so as to draw a spiral on the inner surface.

A temperature sensor 118 is brought into contact with the fixing roller 10, and a signal detected by the temperature sensor 118 is taken into a CPU 132 via an input circuit 131, and
Numeral 32 is configured to control the power supply to the resistance heating element layer 113 via the driver 133 based on the detected fixing roller temperature.

As a method of supplying power to the fixing roller, Japanese Patent Application Laid-Open No. Hei 10-333476 discloses a second conventional example.
Has been proposed in which the conductive adhesive 213 as shown in FIG. Reference numeral 211 denotes a cylindrical body, reference numeral 212 denotes an electric insulating layer, reference numeral 214 denotes a power receiving electrode member, reference numeral 215 denotes a power supply electrode brush, and reference numeral 214a denotes a power receiving unit.

[0012] As shown in FIG.
The fixing heat roller of No. 33476 includes an electric insulating layer 212 on an inner peripheral surface of a cylindrical body 211 made of a metal pipe.
A resistance heating element 216 is formed on the electric insulating layer 212,
A power receiving electrode member 214 is joined to an end of the resistance heating element using a conductive adhesive 213.

[0013]

However, the power receiving electrode member 114 of the first conventional example is fixed by shrink-fitting or shrink-fitting. However, in this fixing method, strict dimensional accuracy and power receiving are required for the inner diameter of the fixing roller and the outer diameter of the cap. The rigidity of the electrode itself is required. Further, if the power receiving electrode member 114 is not firmly fixed, conduction failure occurs during long-time use. If such a state of poor conduction continues, a spark is generated, destroying the electrical insulating layer 112 and causing a leak.

For this reason, it is required that the power receiving electrode member 114 of the fixing roller 10 be securely fixed. However, since the fixing roller 10 is a thin roller, it is difficult to fix the power receiving electrode member 114 directly to the surface thereof with screws or the like. Further, since the fixing roller 10 can reach a high temperature of 200 ° C. or more, it cannot be fixed by soldering.

Further, according to the power supply method described in Japanese Patent Application Laid-Open No. H10-333476, the resistance as a heat generating layer is used to improve the contact state of the power receiving electrode member 214 and to prevent the power receiving electrode member 214 from being inclined. It is necessary to increase the contact area with the heating element 216. For this reason, there is a problem that the heat generation width becomes narrow, the heat capacity of the electrode portion becomes large, and the temperature of the end portion of the fixing roller does not rise. Conversely, if the electrode width is reduced, the contact state becomes unstable, and the power supply brush 21
When the power receiving electrode member 214 is pressed at 5, the power supply electrode member 214 is inclined, or is pushed into the inside of the roller, so that stable power supply cannot be obtained. Further, a conductive adhesive 2 having conductivity and heat resistance.
13 is very expensive, and may cause migration in the insulating layer or flow into the cylindrical body 211 as a metal base, making it difficult to secure insulation for a long period of time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to securely fix a power receiving member to a surface heat-fixing roller, and to secure conduction to a resistance heating element to secure safety. It is an object of the present invention to provide an image forming apparatus having a heat fixing device having high heat resistance and a fast rise time.

[0017]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a fixing roller which is driven to rotate; and a pressure roller which is in contact with the fixing roller at a predetermined pressure and is rotatable. An image forming apparatus having a heat fixing device that heats and fuses the toner image by fusing the transfer material onto which the toner image has been transferred by inserting the transfer material between the two rotating rollers; Comprises a fixing roller and a power supply means for supplying power to the fixing roller, wherein the fixing roller has a hollow cylindrical base having a folded portion whose both ends are turned to the inner peripheral side, and is laminated on the inner surface of the hollow cylindrical base. An electric insulating layer, a resistance heating element laminated on the electric insulation layer, and a power receiving electrode connected to the resistance heating element in the folded portion, wherein the power supply means supplies power to the power receiving electrode. Features That is an image forming apparatus having a heating fixing device.

In this configuration, since the power receiving electrode is provided to be connected to the resistance heating element of the folded portion whose both ends are folded inwardly, it is possible to heat up to the roller end portion and to maximize the width of heat generation. In addition, a thin and narrow power receiving electrode can be formed on the folded inner surface of the metal base of the fixing roller, so that the rising time is short and the conduction to the resistance heating element can be stably ensured. .

According to a second aspect of the present invention, in the image forming apparatus having the heat fixing device according to the first aspect, the folded portion is formed in a tapered shape expanding toward the center of the roller. Is characterized in that at least a part of the electrical connection portion in the axial direction is formed in a shape following the tapered shape.

In this configuration, the end of the base material and the tapered portion of the power receiving electrode are combined, so that the power receiving electrode does not move to the back due to the pressing of the power supply electrode brush, and stably maintains conduction to the resistance heating element. it can.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of a fixing device according to a first embodiment of the present invention, FIG. 2 is a diagram showing a power receiving electrode member of a heating fixing roller provided in the fixing device of FIG. 1, and FIG. 2B is a front view, FIG.
(C) is a perspective view. In FIG. 1 and FIG. 3, which will be described later, only one end of the heat-fixing roller is described, but the other end has the same configuration, and a description thereof will be omitted.

As shown in FIG. 1, a heat generating fixing roller 10 of the fixing device comprises a hollow cylindrical metal base 11, an electric insulating layer 12 laminated on an inner peripheral surface of the metal base 11, and an electric insulating layer 12; And a resistance heating element layer 13 laminated thereon. Further, a bent portion (a bent portion 11a of the metal base 11, a bent portion in which an end portion of the heat fixing roller 10 is bent toward the roller center).
The bent portion 12a of the electrical insulating layer 12, the bent portion 13a of the resistance heating element layer 13) and the bent portion (the bent portion 11 of the metal base 11).
a, bent portion 12a of electrical insulating layer 12, resistance heating element layer 13
Of the metal base 11, the folded portion 12b of the electric insulating layer 12, and the folded portion of the resistance heating element layer 13 in which the inner end of the bent portion 13a is folded inward substantially in parallel with the roller axis. 13b). Note that a release layer may be formed on the surface of the metal base 11 as in the conventional example. Since the heat generating fixing roller 10 has the bent portion as described above, the roller end, which tends to have low rigidity, can have high rigidity.

As shown in FIG. 2, the power receiving electrode member 14
A power receiving portion 14c having a protruding central portion, a power supply portion 14b at an outer peripheral portion in pressure contact with the folded portion 13b of the resistance heating element layer 13, and a substantially disc-shaped connection portion 14a for connecting the power reception portion 14c and the power supply portion 14b. And a cutout portion 14d cut out like a slit from the power supply portion 14a to a part of the connection portion 14a.

The notch 14d allows the power receiving electrode member 14
Can improve the elasticity of the material. Since the elasticity can be improved in this manner, the power receiving electrode member 14
The range of selection of the material used for can be expanded.

As described above, both ends of the metal base 11 of the heat fixing roller 10 are folded inward, and a resistance heating element layer 13 is formed inside the metal base 11 with the insulating layer 12 interposed therebetween. Further, the power receiving electrode member 14 has a disk shape and has a flat power receiving portion 14c for sliding in the center with the power supply brush 15, a power supplying portion 14b for contacting and supplying power to the resistance heating element layer 13, and an improved elastic effect. And a notch 14d. The power receiving electrode member 14 has a thickness t = 0.2 to 1
It is made of a thin metal such as stainless steel or phosphor bronze having spring properties.

When the power receiving electrode member 14 is assembled to the roller, a folded portion (a folded portion 11b of the metal base 11, a folded portion 12b of the electric insulating layer 12, and a folded portion 13b of the resistance heating element layer 13) serve as a power supply portion of the electrode. ), A pressure is applied toward the center of the roller. This pressure is applied by the rigidity of the metal base 11 and the spring property of the power receiving electrode member 14. That is, the folded portion (the folded portion 11b of the metal base 11,
A force toward the center of the roller acts on the folded portion 12b of the electrical insulating layer 12 and the folded portion 13b) of the resistance heating element layer 13.
In other words, a force in the pulling direction acts on the power receiving electrode member 14. As described above, in the present invention, since a force is applied to the power receiving electrode member 14 in the direction in which the power receiving electrode member 14 is pulled, the power receiving electrode member 14 is thinned and does not collapse or deform. The reason is that the thin metal is weak against the compressive force and deforms, but strong against the tensile force.

As described above, since the power receiving electrode member 14 can be made thin, the heat capacity of the electrode portion can be reduced. Further, the temperature can be raised to the end of the heat generating fixing roller 10, and the temperature distribution of the heat fixing roller 10 can be made uniform.

According to the above-mentioned surface heating fixing roller, the power receiving electrode member 14 can be securely fixed, and conduction to the resistance heating element layer 13 is ensured, so that the fixing device is high in safety and has a fast rise time. Can be provided.

FIG. 3 is a cross-sectional view of a main part of a fixing device according to a second embodiment of the present invention. FIG. 4 is a diagram showing a power receiving electrode member of a heat fixing roller provided in the fixing device of FIG.
4A is a sectional view, FIG. 4B is a front view, and FIG. 4C is a perspective view.

As shown in FIG. 3, the fixing device of the second embodiment differs from the fixing device of the first embodiment of FIG.
1b, the folded portion 12b of the electric insulating layer 12 and the folded portion 13b) of the resistance heating element layer 13 are formed in a tapered shape having a large diameter at the center of the roller. That is, the heat fixing roller 1
The folded portion 0 (the folded portion 11b of the metal base 11, the folded portion 12b of the electric insulating layer 12, and the folded portion 13b of the resistance heating element layer 13) are formed in a tapered shape expanding toward the center of the roller.

Further, in the fixing device of the second embodiment, as shown in FIG. 4, the power receiving portion 14e of the power receiving electrode member 14 is formed of a folded portion of the heat generating fixing roller 10 (a folded portion 11b of the metal base 11, an electrically insulating layer 12b). Are formed in a tapered shape that follows the tapered shape of the folded portion 12b of the resistance heating element layer 13 and the folded portion 13b) of the resistance heating element layer 13. Note that the power supply portion 14e and the folded portion (the folded portion 11b of the metal base 11, the electrically insulating layer 1
2 folded portion 12b, folded portion 13 of resistance heating element layer 13
In the case of b), at least a part of the roller in the axial direction may be copied.

In this way, as shown in FIG. 3, the folded portions at the end portions of the base material (the folded portions 11b of the metal base 11, the folded portions 12b of the electrical insulating layer 12, and the folded portions 13b of the resistance heating element layer 13) are formed. By forming the power receiving portion 14e having a tapered power supply portion 14e as shown in FIG. Power receiving electrode member 1
Reference numeral 4 does not move to the back (roller center side) due to the pressing of the power supply electrode brush 15.

FIG. 5 is an explanatory diagram showing a main configuration of an image forming apparatus to which the present invention is applied. The image forming apparatus includes a photosensitive drum 1 on which an electrostatic latent image is formed, and a charging roller 2 that contacts or approaches the photosensitive drum 1 to perform a charging process.
A developing roller 5 for applying toner to the electrostatic latent image on the photosensitive drum 1; a power supply 8 for applying a DC voltage to the charging roller 2; A transfer roller 6 that performs a transfer process on the recording paper P that has been transferred, a cleaning device 7 that removes and collects residual toner on the surface of the photosensitive drum 1, and a photosensitive drum 1
And a fixing device 9 (heating fixing roller 10, pressure roller 20).
Reference numeral 3 denotes exposure such as laser light or light reflected from a document.

An image forming operation in the image forming apparatus configured as described above will be described. First, the surface of the photosensitive drum 1 is uniformly charged to a high potential by supplying a DC voltage from the power supply 8 to the charging roller 2 contacting the photosensitive drum 1.

Immediately thereafter, when the surface of the photosensitive drum 1 is exposed 3, the potential of the exposed portion decreases. Since the exposure 3 has a light amount distribution corresponding to the image density, the exposure 3 forms a potential distribution with respect to the recorded image, that is, an electrostatic latent image on the surface of the photosensitive drum 1.

Next, when the portion on which the electrostatic latent image is formed passes the developing roller 5, toner adheres according to the level of the potential, and a toner image is formed by visualizing the electrostatic latent image. You. Next, the recording paper P is transported at a predetermined timing to a portion where the toner image is formed, and overlaps the toner image. After the toner image is transferred onto the recording paper P by the transfer roller 6, the recording paper P is separated from the photosensitive drum 1.

Next, the separated recording paper P is conveyed through a conveyance path, where the heat-fixing roller 10 and the pressure roller 20
And is discharged out of the apparatus after the heat and pressure fixing. Also,
After the completion of the transfer, the surface of the photosensitive drum 1 is cleaned by the cleaning device 7, and the residual charges are erased by a residual charge erasing means (not shown) to prepare for the next image forming process.

The present invention is not limited to the above embodiment. For example, in the above embodiment, three slits of the power receiving electrode member are provided, but the number of the slits can be increased or decreased as necessary. That is, various modifications can be made without departing from the gist of the present invention.

[0039]

As described above, according to the fixing roller of the first aspect, it is possible to heat up to the roller end, to maximize the heat generation width, to have a fast rise time, and The conduction to the resistance heating element can be stably secured. Further, the dimensional accuracy of the power receiving electrode member can be reduced.

According to the fixing roller of the present invention, the end of the base material and the tapered portion of the power receiving electrode are combined, so that the power receiving electrode does not move backward by the pressing of the power supply electrode brush, and is stable. Thus, conduction to the resistance heating element can be secured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a fixing device according to a first embodiment of the invention.

FIGS. 2A and 2B are diagrams showing a power receiving electrode member of a heat fixing roller provided in the fixing device of FIG. 1, wherein FIG. 2A is a sectional view, FIG. 2B is a front view, and FIG.

FIG. 3 is a sectional view of a main part of a fixing device according to a second embodiment of the invention.

4A and 4B are diagrams showing a power receiving electrode member of a heat fixing roller provided in the fixing device of FIG. 3, wherein FIG. 4A is a sectional view, FIG. 4B is a front view, and FIG. 4C is a perspective view.

FIG. 5 is an explanatory diagram illustrating a main configuration of an image forming apparatus to which the present invention is applied.

FIG. 6 is a side sectional view showing a fixing device based on a heat fixing roller system of a first conventional example.

FIG. 7 is a sectional view of a main part of the fixing device shown in FIG.

8A and 8B are diagrams showing a power receiving electrode used in the fixing device shown in FIG. 6, wherein FIG. 8A is a sectional view, FIG. 8B is a front view, and FIG.
Is a perspective view.

FIG. 9 is a developed view showing an example of a heating pattern of the resistance heating element.

FIG. 10 is a side sectional view showing an example of a resistance heating element of the fixing device.

FIG. 11 is a sectional view of a main part of a fixing device of a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heat generation fixing roller 11 Metal base (hollow cylindrical base) 11b Folded part 12 Electrical insulation layer 12b Folded part 13 Resistance heating element layer 13b Folded part 14 Power receiving electrode member 15 Power supply brush (power supply means) 20 Pressure roller P Recording paper ( Transfer material)

Claims (2)

[Claims] An image forming apparatus includes: a fixing roller that is driven to rotate; and a pressure roller that is rotatably contacted with the fixing roller at a predetermined pressure. A transfer material on which a toner image is transferred between the two rotating rollers is provided. An image forming apparatus having a heat-fixing device that heats and fuses a toner image by being inserted to fuse the toner image onto a transfer material, wherein the fixing device includes a fixing roller and a power supply unit that supplies power to the fixing roller. The roller has a hollow cylindrical base having a folded portion whose both ends are turned to the inner peripheral side, an electric insulating layer laminated on the inner surface of the hollow cylindrical base, and a roller laminated on the electric insulating layer. An image forming apparatus comprising a heating and fixing device, comprising: a resistance heating element; and a power receiving electrode connected to the resistance heating element of the folded portion, wherein the power supply unit supplies power to the power receiving electrode. 2. The folded portion is formed in a tapered shape expanding toward the center of the roller, and at least a part of the electrical connection portion of the power receiving electrode is formed in a shape following the tapered shape at least partially in the axial direction. An image forming apparatus comprising the heat fixing device according to claim 1.