JPH10221989A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device provided with a small-sized cleaning part being usable for a long time and an oil supplying part. SOLUTION: The fixing device is provided with a cleaning web 15 pressed against an endless carrying belt 6 by a pressing means 16 and supplied from a feeding roller 18, to be wound on a winding roller 17, on the upstream side in the moving direction of the endless carrying belt 6 and an oil tank roller 19 incorporating oil, in a position away from the cleaning web 15, on the downstream side of the cleaning web 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an electrophotographic apparatus for fixing an image transferred on a print medium by electrostatic transfer onto the print medium by heat and pressure.

[0002]

2. Description of the Related Art In recent years, in an electrophotographic apparatus, in order to reduce the amount of printing medium used and the cost of the printing apparatus, a printing medium previously cut from a conventional continuous printing medium is used.
By saving labor in the cutting operation after printing and performing printing on both sides of the print medium, the amount of print medium used can be reduced. This also contributes to environmental protection by reducing mass consumption of consumables such as print media and reducing mass disposal.
Recently, it has attracted attention.

In the conventional fixing device, since printing is performed only on one side of a print medium, the print medium 12 is preheated in advance by a preheating device 24 as shown in FIG. In order to prevent transfer (offset phenomenon), a step of preheating before fixing is provided. In FIG.
3 is a transfer image, 21 is a heating roller, 22 is a heater lamp, and 23 is a pressure roller.

However, in an apparatus for printing on both sides of the print medium 12, it is necessary to pass through the fixing device twice, so that the printed surface is two times.
Pressure contact with the fixing device. For this reason, there is a problem in that the toner on the printed surface is heated and melted and slides on the surface of the preheating device 24, so that the surface of the preheating device 24 is contaminated with the toner and, consequently, the printed surface is contaminated. .

To solve this problem, a fixing device that does not use the preheating device 24 has been considered. However, without the preheating device 24, the offset of the toner on the surface of the heating roller 21 increases, so that oil is applied to the surface of the heating roller 21 to improve the releasability between the surface and the molten toner. I have. In such a situation, the configurations shown in FIGS. 6, 7, and 8 have been proposed for the oil supply system of the fixing device.

FIG. 6 shows a web system using an oil web 26 pre-impregnated with oil. This is the most commonly used oil supply device, after the print medium 12 passes between the heating roller 21 and the pressure roller 23,
While the oil web 26 is in direct pressure contact with the surface of the heating roller 21 where the toner is offset, the oil port 2
The configuration is such that oil 20 is supplied from 5.

The heating roller 21 is usually formed of a metal pipe having a diameter of about 100 mm or less and a thickness of about 5 mm, and several heating elements of a heater lamp 22 are built in a hollow portion. ing. A pressure roller 23 made of an elastic body such as rubber having a thickness of several tens of mm is disposed in contact with and opposed to the heating roller 21, and is in pressure contact with the heating roller 21. With the heating roller 21 and the pressure roller 23 rotating, the print medium 12 passes between the two, and the transfer image 13
Is fixed on the print medium 12.

FIG. 7 shows an oil tank roller system in which fine fibers are implanted on the surface of the oil tank roller 19. The roller 19 is impregnated and held with oil 20 having a relatively high viscosity. The heat of the heating roller 21 softens the oil 20 and oozes out from an orifice provided on the surface of the oil tank roller 19. The oil 20
Is transmitted through the fiber planted on the surface of the oil tank roller 19 and is transferred to the surface of the heating roller 21.

In this system, the oil supply unit is disposed on the heating roller 21 side, similarly to the system shown in FIG.
After passing between the heating roller 21 and the pressure roller 23, the oil tank roller 19 is brought into direct pressure contact with the surface of the heating roller 21 where the toner is offset, and the oil 20 is supplied to the heating roller 21 while being driven to rotate.

FIG. 8 is a conceptual diagram showing an oil pan system, which is the most basic system. One end of the core body 28 made of felt is immersed in the oil 20 supplied to the oil pan 27, and the other end is slid while being in direct pressure contact with the surface of the heating roller 21 to supply the oil 20 from the oil pan 27. Has become. 29 in the figure is an oil blade.

[0011]

The conventional fixing devices have the following problems, respectively. The common problem is that the oil supply unit is disposed on the heating roller 21 side, and after the printing medium 12 passes between the heating roller 21 and the pressing roller 23, the oil web Since the oil 20 is supplied while the oil tank roller 26, the oil tank roller 19, the core body 28, etc. are brought into direct pressure contact, the offset toner adheres to the sliding surface, for example, the fibers on the surface of the oil web 26 are clogged, and the oil The feed rate decreases over time. Therefore, the amount of toner to be offset further increases on the surface of the heating roller 21, and the ability to supply oil to the heating roller 21 and the cleaning ability rapidly decrease.

In the method shown in FIG. 6, the oil web 26 impregnated with micro oil is moved so that the oil supply portion with the heating roller 21 is always kept in a new state. Oil web 26
In order to use the oil web for a long time, a long oil web 26 is required, which increases the cost and increases the size of the apparatus. Conversely, when the feed amount is reduced, the offset toner adheres to the oil supply portion, which causes a decrease in oil supply performance and cleaning ability.

In the method shown in FIG. 7, since the surface of the oil tank roller 19 is always in contact with the offset toner on the surface of the heating roller 21, the toner adheres to the fiber on the surface of the oil tank roller 19, and as shown in FIG. The oil supply performance declines with time more rapidly than in the system.

Further, in the method shown in FIG. 8, since the surface is always in contact with the offset toner on the surface of the heating roller 21, the toner adheres to the fibers on the surface of the core 28, and the aging occurs similarly to the method shown in FIG. The oil supply performance drops sharply. There is also a disadvantage that the amount of oil supplied to the core 28 cannot be controlled appropriately. Further, it is necessary to add a blade 29 and the like after the oil is supplied, to remove the excess supply of the oil 20, and to adjust the oil to an appropriate amount, which increases the cost.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to exhibit high fixing ability at high speed.
An object of the present invention is to provide a fixing device provided with a small cleaning unit and an oil supply unit that can be used for a long time.

[0016]

According to a first aspect of the present invention, an image transferred on a print medium by electrostatic transfer is transferred onto a print medium by heat from a heating unit and pressure from a pressurizing unit. The present invention is directed to a fixing device of an electrophotographic apparatus capable of performing printing on both sides of the print medium.

[0017] The cleaning unit and the oil supply unit are separately provided outside the printing medium transport area of at least one of the heating unit and the pressurizing unit.

According to a second aspect of the present invention, an image transferred on a print medium by electrostatic transfer is fixed on the print medium by heat and pressure. It is intended for a fixing device of an electrophotographic apparatus.

A pair of endless conveyor belts stretched over two or more rotating rollers are provided, one side of the endless conveyor belts are overlapped with each other, and a heating element is provided in the vicinity of the overlapping portion to provide heating. And pressurize the rotating roller on one endless transport belt side and the rotating roller on the other endless transport belt side, which are arranged on the downstream side of the endless transport belt moving direction of the heating element. A cleaning unit for cleaning the surface of the endless transport belt and an oil supply unit for supplying oil to the cleaned belt surface are provided on the downstream side of the pressing unit in the moving direction of the endless transport belt. Things.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, according to the present invention, the cleaning section and the oil supply section are separated, so that the cleaning section and the oil supply section have a long service life. The disadvantage of the conventional oil web system, that is, an increase in the size of the device, is eliminated, and a compact fixing device can be provided.

Further, by disposing the oil supply section downstream of the cleaning section, clogging of the oil tank roller can be prevented, and the oil supply can be stabilized for a long period of time, and a highly reliable fixing device can be provided.

Further, an endless conveying belt is provided in a pair,
One side of the endless conveyor belt was overlapped, a heating element was provided in the vicinity of the overlapping portion to form a heating section, and the heating element was disposed on the downstream side of the endless conveyance belt moving direction.
By pressing the rotating roller on one endless transport belt side and the rotating roller on the other endless transport belt side to form a pressing section, the heating section by the heating element and the pressing section by the roller are separated, and Since the functions of (1) and (2) can be made independent, a sufficient heating step length (nip width) and pressure can be ensured, and the startup time of the apparatus can be shortened.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention.

This fixing device comprises a heating section 7 and a pressure section 10 provided opposite thereto. The heating unit 7 has a frame 3 including a pair of side plates 1 and a lamp housing 2, a driving roller 4 is disposed on one side of the frame 3, and a driven roller 5 is provided on the other side of the frame 3 and above the frame 3. Have been. The drive roller 4
An endless transport belt 6 is stretched between the driven rollers 5 and the two driven rollers 5.
An appropriate tension is applied by a tension applying means 14 composed of a spring via the.

In the lamp housing 2, a heating element 8 composed of a plurality of lamps is arranged with a slight gap between the heating element 8 and the endless conveyance belt 6 so as not to contact the endless conveyance belt 6. The lamp housing 2 is also arranged such that one end surface thereof is not in contact with the endless transport belt 6 with a slight gap between the lamp housing 2 and the endless transport belt 6. In this manner, the fixing heating element 8 (including the lamp housing 2) is disposed close to and along one side of the endless transport belt 6.

The lamp housing 2 is formed to have a minimum thickness to reduce the heat capacity, and the surface facing the heating element is mirror-finished so as to reflect the radiant heat of the heating element 8. Fins 2 a are provided between the heating elements 8 in order to reduce a temperature lip caused by rapid heat absorption that occurs when the printing medium 12 passes.

The surface of the drive roller 4 is coated with a member having a friction coefficient of 0.2 or more such as silicon rubber, for example, to prevent slippage with the endless transport belt 6.

The endless transport belt 6 is made of a heat-resistant resin such as fluororesin, polyimide, or polyetherimide, and has a thickness so that heat can be transmitted to the print medium 12 at a sufficient speed even with a low heat transfer coefficient. Is used.

The pressurizing section 10 has a frame 3 'comprising a pair of side plates 1 and a lamp housing 2' on which the heating element 8 is not mounted. A driven roller 9 is disposed on one side of the frame 3 '. The driven roller 5 is provided on the other side and below the frame 3 '. The driven roller 9
An endless transport belt 6 is stretched between the driven rollers 5 and the two driven rollers 5.
An appropriate tension is applied by a tension applying means 14 composed of a spring via the. The driven roller 9 is elastically urged toward the drive roller 4 side of the heating unit 7 by a pressing unit 11 composed of a spring.

The endless transport belt 6 of the heating unit 7 and the pressing unit 1
0, the endless transport belt 6 has a printing medium 12
Are arranged so as to overlap each other with the transfer path therebetween.

The pressurizing section (consisting of the driving roller 4, the endless conveying belt 6, the driven roller 9 having the pressurizing means 11 and the like) is constituted by the heating section (the lamp housing 2 having the heating element 8). Is located immediately after).
In this case, the fixing ability can be improved by melting the transfer image 13 on the print medium 12 and applying pressure immediately after increasing the binding force between the print medium 12 and the transfer image 13.

When the drive roller 4 of the heating unit 7 rotates in the direction of arrow A, the upper endless transport belt 6 also moves in the direction of arrow A. On the other hand, since the driven roller 9 of the pressing unit 10 is pressed by the driving roller 4 via the endless conveyance belt 6 by the pressing unit 11,
The endless transport belt 6 of the pressing unit 10 moves in the direction of arrow B.

The drive roller 4 starts rotating based on a print start signal, and generates heat by energizing the heating element 8 to generate heat.
The temperature is maintained at the set temperature by temperature detecting means (not shown). In this state, the print medium 12 on which the image 13 has been transferred is inserted between the endless conveyance belt 6 of the heating unit 7 and the pressing unit 10.

The transferred image 13 of the printing medium 12 is
Then, it melts while passing through the heating section constituted by the lamp handling 2 and reaches between the driving roller 4 and the driven roller 9. Then, the molten transfer image 13 is pressed by the driving roller 4 and the driven roller 9, and the fixing force is increased by increasing the binding force with the print medium 12.

In this fixing device, since the path of the heating step is formed by a belt line, a long nip width in the running direction of the print medium 12 can be ensured, and the toner is reliably melted. Further, since the pressure applied by the rollers 4 and 9 is performed immediately after the heating, the heating of the rollers 4 and 9 itself becomes unnecessary, and thus the start-up time of the apparatus can be shortened.

The cleaning web 15 is pressed against the surface of the endless transport belt 6 after passing through the drive roller 4 by pressing means 16 made of an elastic material.
One end of the cleaning web 15 is wound up by a winding roller 17 of the cleaning web 15 by a predetermined operation. The other end of the cleaning web 15 is connected to a feeding roller 18.
, And is fed in the direction of arrow C with the operation of the winding roller 17.

The width a of the cleaning web 15 is set to be wider (a> b) than the width b of the print medium 12 in order to prevent offset within the width of the print medium 12 as shown in FIG. A cleaning unit including the cleaning web 15, the pressing unit 16, the take-up roller 17, and the feeding roller 18 is disposed between the driving roller 4 and the driven roller 5, and passes through the cleaning unit so that the endless transport belt 6 is moved. The surface of is cleanly cleaned.

An oil tank roller 19 is disposed facing the upper driven roller 5, and the oil tank roller 1 is disposed on the surface of the endless transport belt 6 cleaned by the cleaning section.
9 makes contact. The oil tank roller 19 has fine fibers planted on its surface and has a relatively high viscosity oil 2.
0 is built in. The oil 20 is softened by the residual heat of the endless transport belt 6 and oozes out from an orifice provided on the surface of the oil tank roller 19. The oil 20 is transferred to the surface of the endless conveyance belt 6 through the fiber planted on the surface of the oil tank roller 19.

As the fibers constituting the cleaning web 15 and the oil tank roller 19, for example, fluororesin fibers, polyimide amide fibers, polyamide fibers, rayon fibers, wholly aromatic aramid fibers and the like are used.
Silicone oil is used as the oil.

As described above, according to the embodiment of the present invention,
By separating the cleaning section and the oil supply section, the cleaning web 15 does not need to have a predetermined thickness (about 1 mm or more) to impregnate and hold the oil 20 like the oil web 26, and can be made thin. it can. By using the thin cleaning web 15, if the life is the same, the diameters of the rollers 17, 18 can be reduced.
The size of the device can be reduced.

By arranging the oil supply section after the cleaning section, clogging of the fiber surface can be prevented. Thus, the supply of oil to the surface of the endless transport belt 6 is stably performed for a long period of time.

In the present embodiment, the cleaning web 15
Is disposed on the heating unit 7 side, but the cleaning web 15 may be disposed on the pressing unit 10 side to indirectly remove the offset on the heating unit 7 side.

FIG. 3 is a partial schematic configuration diagram of a fixing device according to the second embodiment. In this example, pressing means 1
6 is a guide member made of a metal such as aluminum or a synthetic resin such as polyacetal, in which guide portions 30 and 30 having rounded sides are protruded and formed with concave portions 31 between the guide portions 30. And a spring 33 for pressing the cleaning web 15 toward the endless transport belt 6 via the guide member 32.

By using the guide member 32 having the plurality of guide portions 30 as described above, the endless transport belt 6 can be cleaned a plurality of times by one rotation.

FIG. 4 is a schematic configuration diagram of a fixing device according to the third embodiment. In the case of this example, the heating roller 21 is used instead of the endless conveyance belt 6, and the heating roller 2 is used.
The cleaning web 15, the pressing means 16, the take-up roller 1
7. A cleaning unit including a feeding roller 18 is arranged, and an oil tank roller 19 is further provided downstream of the cleaning unit.

In this embodiment, guide portions 30, 30 are provided on both sides as shown in FIG.
When the guide member 32 having the shape is used, a part of the heating roller 21 enters into the concave portion 31, the contact area between the heating roller 21 and the cleaning web 15 is increased, and the cleaning effect is further improved.

In the above embodiment, the cleaning web 15 is not impregnated with anything. However, the cleaning web 15 may be impregnated with an appropriate amount of a cleaning liquid (eg, a volatile organic liquid) or oil.

[0048]

According to the present invention, as described above, since the cleaning section and the oil supply section are separated from each other, the cleaning section and the oil supply section have a long service life. The disadvantage of the oil web system, that is, an increase in the size of the device, is eliminated, and a small fixing device can be provided.

Further, by disposing the oil supply section downstream of the cleaning section, clogging of the oil tank roller can be prevented, the oil supply can be stabilized for a long time, and a highly reliable fixing device can be provided.

Further, a pair of endless conveying belts is provided,
One side of the endless conveyor belt was overlapped, a heating element was provided in the vicinity of the overlapping portion to form a heating section, and the heating element was disposed on the downstream side of the endless conveyance belt moving direction.
By pressing the rotating roller on one endless transport belt side and the rotating roller on the other endless transport belt side to form a pressing section, the heating section by the heating element and the pressing section by the roller are separated, and Since the functions of (1) and (2) can be made independent, a sufficient heating step length (nip width) and pressure can be ensured, and the startup time of the apparatus can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a partial side view showing a relationship between an endless belt, a cleaning web, and a print medium in the fixing device.

FIG. 3 is a partial schematic configuration diagram of a fixing device according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a fixing device according to a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional fixing device.

FIG. 6 is a schematic configuration diagram of another conventional fixing device.

FIG. 7 is a schematic configuration diagram of still another conventional fixing device.

FIG. 8 is a schematic configuration diagram of still another conventional fixing device.

[Explanation of symbols]

 Reference Signs List 4 driving roller 5, 9 driven roller 6 endless transport belt 7 heating unit 8 heating element 10 pressing unit 11 pressing unit 12 printing medium 13 transfer image 15 cleaning web 16 pressing unit 17 take-up roller 18 feeding roller 19 oil tank roller Reference Signs List 20 oil 21 heating roller 23 pressure roller 30 guide portion 31 concave portion 32 guide member 33 spring

Claims (6)

[Claims] 1. An electrophotographic apparatus capable of printing on both sides of a printing medium, wherein the image transferred on the printing medium by electrostatic transfer is fixed on the printing medium by heat from a heating unit and pressure from a pressing unit. In the fixing device, a cleaning unit and an oil supply unit are separately provided outside a print medium transport area of at least one of the heating unit and the pressure unit. 2. The fixing device according to claim 1, wherein the oil supply unit is provided downstream of the cleaning unit. 3. A fixing device for an electrophotographic apparatus capable of printing on both sides of a print medium, wherein the image transferred onto the print medium by electrostatic transfer is fixed on the print medium by heat and pressure. A pair of endless conveyor belts stretched over rotating rollers are provided, and one side of the endless conveyor belts are overlapped with each other, and a heating element is provided near the overlapping portion to form a heating area. The pressing roller presses the rotating roller on one endless conveying belt side and the rotating roller on the other endless conveying belt side, which are arranged on the downstream side in the moving direction of the conveyer belt. A fixing device comprising: a cleaning unit that cleans a surface of an endless conveyance belt; and an oil supply unit that supplies oil to a surface of the cleaned belt, on a downstream side in a movement direction of the conveyance belt. 4. The fixing device according to claim 1, wherein the cleaning unit has a cleaning web that can be wound up and pressing means for pressing the cleaning web against a surface to be cleaned. . 5. The fixing device according to claim 4, wherein the width of the cleaning web is wider than the width of a print medium. 6. A fixing device according to claim 4, wherein said pressing means includes a guide portion projecting to both sides and a guide member having a concave portion between said guide portions.