JPH1115318A - Heating roller and heat fixing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating roller and a fixing device using it, which can be applied to a fixing device of a direct heating system having plural heating layers and enable stable current carrying for a long period. SOLUTION: This heat fixing device is equipped with plural heating layers, 20 and 22, of different widths in an inside contact manner and positions inside a core metal 17 across a dielectric layer 19. Each heating layer, 20 or 22, is equipped with a power transmitting means which transmits electric power separately, and with a heating roller 11 which rotates on a support. The power transmitting means is fixed in an inside contact manner and separately to plural heating layers, 20 and 22, and is composed of disk-shaped rotary electrodes, 24 and 25, which rotate together with a rotation of the heating roller 11, and fixed electrodes, 31 and 32, which are fixed to the support and slide contacting respectively with the rotary electrodes, 24 and 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating roller used in an electrophotographic copying machine, a printer, a facsimile, a heating and erasing device for paper by thermochromism, and a heating fixing device using the same.

[0002]

2. Description of the Related Art In general, in an electrophotographic copying machine, a printer, a facsimile, and the like, fixing of a developed image is performed.
A heating fixing device including a heating roller and a pressure roller is used. In this heat fixing device, printing paper on which toner is transferred and developed is inserted between rollers between a heating roller and a pressure roller. As a result, the toner for forming the image is heated and melted and fused and fixed on the printing paper.

[0003] In recent years, in these heat fixing devices, the power supply to the heating roller is cut off when not in use for the purpose of reducing power consumption. On the other hand, there is no waiting time during use, and an instant rise is required, and the surface temperature of the heating roller is required to immediately reach a predetermined temperature. In this case, the time required for the printing paper to move to the fixing unit is usually 7
Since the time is about seconds, the time required for the heating roller to reach the predetermined temperature is about 10 seconds.

As a heat fixing device provided with a heat roller which satisfies such a demand, for example, the one shown in FIGS. 12 and 13 is disclosed in JP-A-6-33233. The heat roller 1 of the heat fixing device is composed of a base 2 made of an alumina pipe. On the outer peripheral surface of the base 2, a heating layer 3 made of a resistance heating substance is formed in a pattern. A protective layer (insulating layer) 4 for protecting the heat generating layer 3 and providing insulation is laminated on the outer peripheral surface of the heat generating layer 3,
Is covered with a release layer 5.

[0005] In this heating roller 1, as shown in FIG. 12, a pair of electrode rings 6 are formed at both ends of the base 2. Further, a pair of electrode brushes 7 is mounted on a frame (not shown).
Has been fixed. The electrode brush 7 is electrically connected to an external power supply (not shown), and the heating layer 3 is energized by bringing the electrode ring 6 into contact with the electrode brush 7. In this heating roller 1, since the heat generating layer 3 is in direct contact with the base 2, the surface temperature is raised to a predetermined temperature in a shorter time compared to a method of radiantly heating the roller with a halogen heater which has been widely used in the past. Can be done.

Further, the present inventors have proposed a heating roller in which conductive fibers are arranged according to a specific formula to obtain a required resistance value and to raise the temperature very quickly. Here, carbon fibers having high thermal conductivity are used, and a carbon fiber having a uniform temperature distribution is obtained.

[0007]

However, in these heating rollers, when papers having different widths with respect to the maximum paper passing width are fixed, a phenomenon occurs in which the temperature at the end differs. That is, the heating roller appropriately adjusted for the maximum sheet passing width (for example, the length of A3) is applied to the small width paper (for example,
5), heat is supplied by the amount of heat consumed by the paper at the center, and the temperature in an appropriate range is maintained. However, at both ends, heat is not consumed by the paper. Then, heat is stored, and the temperatures of the pressure roller and the heating roller rise. As a result, if a wide sheet of paper is passed immediately after the endurance of the bearing member has decreased and the end portion temperature has risen, the temperature will be higher than the set temperature, and fixing errors (hot offset) and conveyance errors at the end portions will occur. I do.

[0008] This temperature rise at the end has a similar problem in a heating method using a halogen heater or the like. Particularly, in the direct heating method, the insulating layer and the heat generating layer are in contact with the roller.
The rise in temperature at the end directly affects the insulating layer and the heat generating layer at the end, and deteriorates the durability due to thermal degradation.

In view of the above, a fixing roller of a direct heating type, which includes a plurality of heat generating layers having different widths and positions, and which can switch the heat generating layers according to the paper width, can be considered. According to this heating roller, it is possible to effectively reduce the rise in the temperature of the end portion, without generating wasteful energy consumption during continuous paper feeding with a short sheet width, and also to suppress the thermal deterioration of the end portion.

[0010] However, the structure for transmitting electric power to the plurality of heat generating layers becomes complicated. For example, as shown in FIG. 12, when the power transmission means is an electrode ring 6 connected to the outer periphery of the heat generating layer 3, a plurality of electrode rings corresponding to the paper width cannot be provided. Further, providing the electrode outside may cause toner adhesion and may not be suitable for long-term use.

The present invention has been made in view of the above circumstances, and has as its object to be applicable to a direct heating type fixing device having a plurality of heating layers, and to stably reduce power consumption for a long period of time. And a fixing device using the same.

[0012]

According to a first aspect of the present invention, there is provided a heating roller in which a plurality of heat generating layers having different widths and positions are inscribed on an inner surface of a metal core via an insulating layer. In the heating roller which includes power transmission means for separately transmitting power, and is supported and rotated by the support, the power transmission means includes:
A disk-shaped rotating electrode that is separately inscribed and fixed to the plurality of heat generating layers and rotates with the rotation of the heating roller, and a fixed electrode that is fixed to the support and slides in contact with the rotating electrode, respectively. It is characterized by comprising.

According to a second aspect of the present invention, in the heating roller, the plurality of heat generating layers include a first heat generating layer on a metal core arranged at a width through which a paper having a maximum width passes, and a heat generating layer disposed inside the first heat generating layer. A second heat generating layer which is inscribed through an insulating layer and is arranged at a width through which a sheet of the minimum width is passed, and wherein the first heat generating layer has a disc-like shape which rotates with the rotation of the heating roller. A first rotating electrode is inscribed and fixed, and a disk-shaped second rotating electrode that rotates with the rotation of the heating roller is fixed to the second heat generating layer.

According to a third aspect of the present invention, in the heating roller, the first rotary electrode has an opening at the center of rotation, and a wiring of a second fixed electrode connected to the second rotary electrode through the opening is provided. I do.

According to a fourth aspect of the present invention, in the heating roller, the first sliding surface where the first fixed electrode is in contact with the first rotating electrode includes a periphery of the opening, and the second fixed electrode is in contact with the second rotating electrode. The second sliding surface includes a rotation center.

According to a fifth aspect of the present invention, in the heating roller, the first rotating electrode has an opening at the center of rotation, and the opening is slid in contact with the second fixed electrode extending from the second rotating electrode via an insulating layer. A second sliding surface is provided, a first sliding surface where the first fixed electrode contacts the first rotating electrode includes a periphery of the opening, and the second sliding surface includes a rotation center. Features.

According to a sixth aspect of the present invention, there is provided a heating roller comprising the heating roller according to any one of the first to fifth aspects and a pressure roller rotatably pressed against the heating roller. The present invention is characterized by a heating and fixing device for sandwiching printing paper between rollers and fusing toner to the printing paper.

According to the present invention, electric power is transmitted from the sliding surface of the fixed electrode and the disk-shaped rotating electrode separately inscribed in the plurality of heat generating layers. This makes it possible to measure the temperature according to the sheet passing width and to transmit stable power for a long time.

According to the second aspect of the present invention, since the first heat generating layer corresponding to the maximum sheet passing width is disposed on the front side, it is possible to uniformly heat the sheet according to the maximum sheet passing width.

According to the third aspect of the present invention, power can be transmitted to the second heat generating layer having a small paper width through the opening.
This structure is simple.

According to the fourth aspect of the invention, the sliding surface of the electrode is located as close as possible to the center of rotation. At this position, the temperature rise is low and the sliding speed is low, so that power can be stably transmitted over a long period of time.

According to the fifth aspect of the present invention, the wiring to the second fixed electrode can be made short, and the power can be stably used for a long time in the internal second heating layer having a small paper width.

The heating roller according to any one of claims 1 to 5 can be used as a heat fixing device by being combined with a pressure roller.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a heat fixing device according to the present invention will be described with reference to the drawings. The same components as those in the description of the related art are denoted by the same reference numerals, and detailed description is omitted.
Only different parts will be described.

As shown in FIG. 1, reference numeral 11 denotes a heating roller, and both ends thereof are rotatably supported by a pair of heating roller bearings 12. A drive gear 13 is provided on one side (hereinafter referred to as a drive side) of the heating roller bearing 12.
The drive gear 13 is driven by a motor (not shown), and the heating roller 11 rotates.

A pressure roller 14 is arranged in parallel with the heating roller 11. Both ends of the pressure roller 14 are rotatably supported by pressure roller bearings 15. The heating roller 11 pinches the printing paper while rotating together with the pressure roller 14. Although the toner is transferred to the printing paper, the toner is heated and melted by passing between the rollers 11 and 14, and the printing paper is fused and fixed.

The heating roller 11 has a hollow cylindrical aluminum substrate 17 having a diameter of 20 mm, a length of 360 mm, and a thickness of 0.4 mm provided with a heat-shrinkable tube of PFA resin as a release layer 16 on the surface thereof. The heat generating layer 18 is fixed by a heat-resistant adhesive. As shown in detail in FIG. 2, the heat generating layer 18 includes an electric insulating layer (first insulating layer) 19 composed of mica and a PA
Electric heating layer (first heating layer) 20 made of N-based carbon fiber
And an electrical insulation layer (second insulation layer) 21 composed of mica
And an electric heating layer (second heating layer) 22 made of carbon fiber.

The heating layers 20 and 22 are made of, for example, a polyimide resin, a bismaleimide resin, a phenol resin, or the like, in a state where carbon fibers as resistance heating substances are arranged spirally or linearly in the roller axis direction evenly without gaps. 0.01-0.5 mm thick impregnated with a predetermined ratio of heat-resistant resin
From the prepreg sheet by heat molding or the like. Surface resistance is 0.62Ω / cm, fiber width 31mm,
The fiber angle (winding angle) crossing the fixing roller axial direction is 6
0 degrees. The width of the first heat generating layer 20 is 310 mm, and the width of the second heat generating layer is 210 mm.

As shown in FIG. 3, a disc-shaped (cap-shaped) first rotating electrode 24 made of nickel-plated aluminum is press-fitted into the inside of the first heating layer 20 at the driven end 23 of the heating roller 11. As a result, it is internally fixed while being electrically connected.

As shown in FIGS. 4A and 4B, the first rotating electrode 24 has a disk portion 24a and its disk portion 24.
The inner wall 24c includes an outer wall 24b and an inner wall 24c. The opening 24d is formed inside the inner wall 24c (at the center of the disk portion 24a). This disk portion 24a,
Due to the two peripheral walls 24b and 24c, the cross section of the rotating electrode has a U-shape. Further, a split groove 24e is cut into the peripheral wall portion 24b. The peripheral wall 24b has elasticity by the split groove 24e. When the first rotating electrode 24 is pressed into the heating roller 11 by this elasticity, the peripheral wall 2
4b is designed so as to be in close contact with the first heat generating layer 20.

A disc-shaped (cap-shaped) aluminum-plated nickel-plated second rotating electrode 25 is press-fitted inside the second heat generating layer 22 on the driven side 23 and is electrically connected to the second heating layer 22. Inscribed and fixed. This second
As shown in FIGS. 5A and 5B, the rotating electrode 25 includes a disk 25a and an outer peripheral wall 25b erected from the disk 25a. Due to the disk portion 25a and the outer peripheral wall 25b, the cross section of the rotating electrode has a U shape. Air holes 25c at desired positions of the disk portion 25a
And a split groove 25d is cut into the outer peripheral wall 25b. The outer peripheral wall 25 is formed
b has elasticity. Due to this elasticity, the outer peripheral wall 25b is designed to be in close contact with the second heat generating layer 22 when the second rotary electrode 25 is press-fitted into the heating roller 11.

On the other hand, as shown in FIG.
The electrode fixing base 26 is provided on the side wall (not shown) of the
Are fixed, and a first leaf spring 27 and a second leaf spring 28 made of a conductive material are fixed to the electrode fixing base 26. These leaf springs 27 and 28 are connected to an external power source 30 via a control unit 29.
Is electrically connected to The control unit 29 has a switching function of controlling power transmission to the first heat generation layer 20 and the second heat generation layer 22 manually or automatically according to the width of the paper.

A conductive brush (first fixed electrode) 31 is fixed to the tip of the first leaf spring 27 with a conductive adhesive or the like. The first fixed electrode 31 is pressed against the first rotating electrode 24 by the urging force of the leaf spring 27 with the brush surface facing the inner peripheral wall 24c. In the pressed state, the first rotating electrode 24 rotates according to the rotation of the heating roller 11, but the first fixed electrode 31 is fixed, and the first rotating electrode 24 and the first fixed electrode 31 are electrically connected. It is slid in the state that it was.

The second leaf spring 28 passes through the opening 24d of the first rotating electrode 24, and has a columnar conductive brush (second fixed electrode) 32 at its tip with a conductive adhesive or the like. The surface is fixed to the disk portion 25a.
It is desirable that the portion of the second leaf spring 28 that passes through the opening 24d be insulated by an insulating material or the like. The brush surface of the second fixed electrode 32 is in contact with a region including the rotation center of the disk portion 25a by the urging force of the second leaf spring 28. In this contacted state, the second rotation is performed according to the rotation of the heating roller 11.
The rotating electrode 25 rotates, but the second fixed electrode 32 is fixed, and the second rotating electrode 25 and the second fixed electrode 32 slide while being electrically connected.

On the other hand, as shown in FIG.
A cap-shaped rotating electrode (hereinafter referred to as a common rotating electrode) 33 made of nickel-plated aluminum is press-fitted into the energizing heat-generating layers 20 and 22 on the drive side. The common rotating electrode 33 includes a first annular portion 33a inscribed in the first heat generating layer 20 and a second annular portion 33 in inscribed in the second heat generating layer 22.
b and a connecting portion 33c for connecting them. The first annular portion 33a is formed in a similar shape to the second rotating electrode 25, and is elastically supported by a common leaf spring 35 from an electrode fixing base 34 fixed to a drive-side frame body side wall (not shown). The common fixed electrode 36 is slidably and electrically connected to the common fixed electrode 36 in a region including the rotation center.

In the heat-fixing apparatus having the above-described configuration, when the A3 vertical paper is inserted for fixing, the control circuit 29 is switched to energize the first heating layer 20. Thus, the surface of the heating roll corresponding to the A3 length is heated. On the other hand, when the B5 vertical paper is inserted, the power of the first heat generating layer 20 is turned off, and the second heat generating layer 22 is switched to be energized. Thereby, only the width corresponding to the B5 length can be heated.

The heating roller 11 was incorporated in a copying machine manufactured by Ricoh Co., Ltd., and 200 sheets of B5 lengthwise paper were passed through, and the temperature at the center and the end of the paper passing, the integrated power consumption, and the temperature rise time were measured. did. The heating time was 10.8 seconds, and the accumulated power consumption was 98 Wh. At this time, the temperature at the center of the sheet passing was 185 ° C., and the surface temperature of the heating roller at a portion corresponding to the vertical end of B5 was 190 ° C., so that an appropriate temperature for fixing was maintained. On the other hand, the surface temperature of the portion corresponding to the A3 end was as low as 150 ° C.

On the other hand, for comparison, a heating roller prepared in exactly the same manner except that the second heating layer 22 was not provided was used, and the measurement was performed under exactly the same conditions except that the first heating layer 20 was energized. The warming time was as fast as 10.2 seconds,
The accumulated power consumption was as high as 148 Wh, and the temperature at the central portion of the paper passing was properly maintained at 185 ° C., but the roller surface temperature at the position corresponding to the end of B5 was slightly as high as 196 ° C. The temperature at the position corresponding to the end of A3 is 255 ° C
And was unnecessarily growing.

As described above, according to this embodiment, since the roller body is directly heated by the heat generating layer, for example, compared with a method of heating with radiant heat of a halogen heater which has been widely used in the past, the roller body is heated in a shorter time. The surface temperature can be raised to a predetermined temperature.

It is also understood that when the paper width is narrow, energy can be saved without raising the edge.

Furthermore, since the sliding electrodes are arranged at the center of rotation or at a position as close as possible to the center of rotation, that is, at the position farthest from the current-carrying layers 20, 22, the rise in the temperature of the sliding surface is small. Therefore, it can be used stably for a long period of time.

[0042]

[Modifications 1 to 3] FIGS. 6 to 11 show various modifications of the structure of the contact portion between the rotating electrode and the fixed electrode.

(Modification 1) As shown in FIGS. 6 and 7,
Instead of the first rotating electrode 24 of the embodiment, the first rotating electrode 24 'provided simply with the opening 24d at the center of the disk portion 24a without using the inner wall 24c may be used. The first in this case
The fixed electrode 31 'is formed, for example, in an annular shape. This annular first fixed electrode 31 ′ includes a pair of upper and lower leaf springs 27,
27, the sliding surface (brush surface) is slidably contacted toward the disk surface 24a. Since the sliding surface is disposed around the opening 24d, the temperature of the sliding surface does not become high even after long-term use.

(Modification 2) As shown in FIGS. 8 and 9,
Instead of the first fixed electrode 31 of the embodiment, an annular first fixed electrode 31 ″ having an inner surface as a brush surface may be used.
The first fixed electrode 31 of the second modification includes a pair of leaf springs 2.
It is supported up and down by 7, 27. The first fixed electrode 31 '' includes an elastic member, and a cutout 31a is provided on one side of the first fixed electrode 31 '' so that a biasing force can act toward the center. As a result, the first fixed electrode 31 is configured so that an urging force acts toward the center, and the sliding surface (brush surface) is slidably contacted toward the inner wall 24c.

(Modification 3) As shown in FIGS. 10 and 11, in the embodiment, a metal member 37 extending from the disk surface 25a of the second rotating electrode 25 'is provided. The sliding surface 38 with the second fixed electrode 32 may be provided near the opening 24d. Generally, leaf springs 27, 28
Is preferably configured to be resistant to deformation in the rotation direction due to the rotation of the rotating electrode 24. However, in the embodiment, since the distance between the second leaf spring 28 and the second rotary electrode 25 is long, it is difficult to configure the second leaf spring 28 to be strong against deformation. However, in such a configuration, the second leaf spring 28 is shortened. And stable contact can be performed.

In the structure of the third modification, the first heating layer 20
In addition, the power transmission system to the second heat generating layer 22 is kept insulated. The insulation between the sliding surface 38 and the first rotary electrode 24 is made by using the gap 39 as an insulating layer, and the first fixed electrode 31 ′
The second fixed electrode 32 can be formed continuously and integrally with the gap 40 as an insulating layer. Also, in this case,
The metal member 36 need only be electrically connected without being supported.

In the first to third modifications, the other points are substantially the same as those of the configuration and operation described in the embodiment, and thus detailed description is omitted.

The heat generating layer is not limited to a laminated one, but may be a divided one in the same plane.

Although the heat fixing device has been described above, the present invention can also be applied to a heat roller of a thermochromic heat erasing device and a heat fixing device used in other heat roller type heat treatment equipment.

[0050]

As described above, according to the first aspect of the present invention, a heating roller having a plurality of energized heat generating layers capable of appropriately increasing the temperature with respect to the sheet passing width can be used for a long time. Stable energization can be performed.

According to the second aspect of the present invention, heating can be performed evenly in accordance with the paper having the maximum width, and even if the paper having a short width is passed, the edge temperature does not increase. .

According to the third aspect of the present invention, the configuration for transmitting power to the second heat generating layer having a small internal paper width is facilitated by a simple configuration.

According to the fourth aspect of the present invention, since the electrode sliding surface of the power transmission means is in contact with a portion as close as possible to the center of rotation, power can be transmitted stably for a long period of time.

According to the fifth aspect of the present invention, power can be stably used for a long period of time for transmitting power to the second heat generating layer having a small paper width inside.

The heating roller according to any one of claims 1 to 5 can be used as a heat fixing device.

[Brief description of the drawings]

FIG. 1 is a partially cutaway explanatory view for explaining the structure of a heating device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the heating roller of FIG.

FIG. 3 is a longitudinal sectional view of a main part of the heating roller of FIG. 1;

4A and 4B are diagrams illustrating the relationship between the structure of a first rotating electrode shown in FIG. 3 and a first fixed electrode, FIG. 4A being a plan view,
FIG. 4B is a side sectional view.

5A and 5B are diagrams for explaining the relationship between the structure of the second rotating electrode shown in FIG. 3 and a second fixed electrode. FIG.
FIG. 5B is a side sectional view.

FIG. 6 is a longitudinal sectional view of a driven side of a heating roller according to a first modification of the present invention.

FIG. 7 is an exploded perspective view illustrating a relationship between the structure of the first rotating electrode shown in FIG. 6 and a first fixed electrode.

FIG. 8 is a partial longitudinal sectional view of a driven side of a heating roller according to a second modification of the present invention.

9 is an exploded perspective view illustrating a relationship between a structure of a first rotating electrode shown in FIG. 7 and a first fixed electrode.

FIG. 10 is a longitudinal sectional view of a driven side of a heating roller according to a third modification of the present invention.

FIG. 11 is a perspective view illustrating the relationship between the structure of both rotating electrodes shown in FIG. 7 and a fixed electrode.

FIG. 12 is a partially cutaway side view for explaining the structure of a heating roller of a heating device according to the prior art.

FIG. 13 is a cross-sectional view illustrating a cross-sectional structure of the heating roller of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Heating roller 17 ... Core metal 18 ... Electric heating layer 19 ... 1st insulating layer 20 ... 1st heating layer 21 ... 2nd insulating layer 22 ... 2nd heating layer 24 ... 1st rotating electrode 24d ... Opening 25 ... 2nd Rotating electrode 31: first fixed electrode 32: second fixed electrode

Claims (6)

[Claims] 1. A plurality of heat generating layers having different widths and positions are inscribed on an inner surface of a metal core via an insulating layer, and a power transmitting means for separately transmitting power to the plurality of heat generating layers is provided. In the heating roller that is supported and rotates, the power transmission unit is separately inscribed and fixed to the plurality of heating layers, and a disk-shaped rotating electrode that rotates with the rotation of the heating roller, and is fixed to the support, A heating roller, comprising: a fixed electrode that slides in contact with the rotating electrode. 2. The heating layer according to claim 1, wherein the plurality of heating layers include a first heating layer on a cored bar arranged at a width through which a paper having a maximum width is passed, and an inner insulating layer inside the first heating layer. And a second heat generating layer arranged in a width in which a sheet having a minimum width is passed through the first heat generating layer. The first heat generating layer has a first rotating electrode in the form of a disc which rotates with the rotation of the heating roller. The second heat generating layer is in contact with and fixed to the second heat generating layer.
The heating roller according to claim 1, wherein the rotating electrode is internally fixed. 3. The device according to claim 2, wherein the first rotating electrode has an opening at the center of rotation, and a wiring of a second fixed electrode connected to the second rotating electrode through the opening is provided. Heating roller. 4. A first sliding surface where the first fixed electrode contacts the first rotating electrode includes a periphery of the opening, and
The heating roller according to claim 3, wherein the second sliding surface where the fixed electrode contacts the second rotating electrode includes a rotation center. 5. The first rotating electrode has an opening at the center of rotation, and the opening has a second sliding surface which slides in contact with a second fixed electrode extending from the second rotating electrode via an insulating layer. A first fixed electrode provided in contact with the first rotating electrode;
The sliding surface includes a periphery of the opening, and the second sliding surface includes:
The heating roller according to claim 2, further comprising a rotation center. 6. A heating roller comprising the heating roller according to claim 1, and a pressure roller rotatably pressed against the heating roller. A heat fixing device for nipping and fusing toner to printing paper.