JPH10307502A - Belt nip type fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt nip type fixing device which can improve the degree of freedom in the formation and arrangement of a cleaning device without generating oil leakage. SOLUTION: This fixing device, which is provided with a belt 2 formed so as to run by forming a belt nip part in a space to the periphery of a heating roller 1, involves an oil transfer roller 6 provided between an oil tank roller 5 for supplying oil for toner mold releasing layer and the heating roller 1 so as to apply oil A to the outer periphery of the heating roller 1. This device is stored in a casing as a unit including a member such as a cleaning roller 7, and the casing 2 is formed so as to be detachable and re-attachable from/to the housing of the fixing device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device in an image forming apparatus such as a copying machine or various printers.
In particular, the present invention relates to a belt nip type fixing device in which a cleaning mechanism for removing toner remaining as an offset on a heating roller and an oil applying mechanism for applying an oil applied as a toner release layer are improved.

[0002]

2. Description of the Related Art In various image forming apparatuses such as an electrophotographic copying machine and a laser printer, a toner image charged on a peripheral surface of a photosensitive drum is transferred to a sheet supplied as an image carrier, and thereafter, undetermined. A fixing device is provided for heating and melting the deposited toner image to fix it on paper. The basic configuration of this fixing device is such that a pair of a heat-fixing roller and a pressure roller are arranged in a path through which a sheet passes, and the pair of rollers heats the sheet while applying pressure to fix the toner image. It is to let.

In such a fixing device, in order to remove the toner image remaining as an offset on the peripheral surface of the heating roller after the fixing operation so as not to hinder the fixing to the next sheet, the remaining toner is peeled and removed. Cleaning device is provided. In order to quickly fix the toner on the paper side, an oil application device is usually provided for applying oil to the peripheral surface of the heating roller to improve the releasability of the toner.

[0004] As an oil application device, there is known an oil application device using an oil tank roller as described in Japanese Utility Model Publication No. 3-10525, for example. This oil tank roller has a configuration in which an infiltrating member such as felt is wound around the peripheral surface of a metal tube filled with oil, and the oil is permeated into the felt through a minute hole opened in the metal tube. is there. In the example described in this publication, unevenness of oil application is eliminated by interposing a transfer roller for applying oil instead of bringing the oil tank roller into direct contact with the heating roller.

On the other hand, instead of the roller-type fixing device described in the above-mentioned publication, a belt nip type fixing device which can secure a sufficient fixing time even when the sheet conveying speed is increased, by taking a long heating time. Has become widely used. The belt nip type fixing device has an advantage that the amount of oil applied can be significantly reduced because the offset is small as compared with the roller type fixing device.

[0006]

However, in the fixing device of the pair of the heating roller and the pressure roller described in the above publication, the required amount of oil to be applied is larger than that in the belt nip system. Needs to be increased. If the number of holes to be opened in the metal pipe of the oil tank roller is increased or the inner diameter thereof is increased so as to increase the supply amount, oil leakage becomes a serious problem.

That is, the oil tank roller is a part that is removed or incorporated into the fixing device unit when replenishing or replacing when the oil is exhausted. In some cases, oil may leak. For this reason, the oil may enter not only the inside of the fixing unit but also other units of the copying machine, and the maintenance and inspection work is considerably complicated and long, which greatly affects the operation time of the apparatus.

As described above, in the roller-pair type fixing device,
Because of the large amount of offset, there is a lower limit on the amount of oil to be applied as a release agent. Even at this lower limit, there is no sufficient measure against oil leakage.

In a roller-pair type fixing device, the amount of toner offset is large. Therefore, a cleaning device for removing the toner is forcibly provided by, for example, bringing a cleaning roller or a blade into direct contact with the peripheral surface of a heating roller. It is limited to a method of peeling. For this reason, the design of the cleaning device is greatly restricted. For example, the cleaning device can be reduced in size or the cleaning device can be unitized to easily replace an expensive fixing unit including a heating roller and a pressure roller. Absent.

As described above, in the conventional roller-pair type fixing device, even if the oil tank roller is used, there is a problem that a trouble due to oil leakage occurs and the design of the cleaning device is largely restricted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a belt nip type fixing device which does not cause oil leakage and can improve the degree of freedom of the configuration and arrangement of the cleaning device.

[0012]

SUMMARY OF THE INVENTION The present invention provides a belt nip type fixing device having a heating roller which is driven to rotate, and an endless belt which runs while forming a belt nip portion between the heating roller and a peripheral surface of the heating roller. An oil tank roller for enclosing oil to be applied as a toner release layer on the peripheral surface of the heating roller and allowing the oil to penetrate the peripheral surface; and an oil tank roller on the peripheral surface of the oil tank roller and the heating roller simultaneously. And an oil transfer roller for applying oil from the oil tank roller to the peripheral surface of the heating roller in contact with the heating roller.

According to this configuration, since the oil transfer roller is interposed without directly contacting the oil tank roller with the heating roller, it is possible to uniformly apply the oil to the peripheral surface of the heating roller.

[0014]

DETAILED DESCRIPTION OF THE INVENTION A belt according to the first aspect of the present invention includes a heating roller that is driven to rotate, and an endless belt that runs while forming a belt nip portion between the heating roller and a peripheral surface of the heating roller. An oil tank roller, which is a nip type fixing device, which encloses oil to be applied as a toner release layer on a peripheral surface of a heating roller and allows the oil to infiltrate the peripheral surface,
An oil transfer roller that simultaneously contacts the peripheral surfaces of the oil tank roller and the heating roller to apply oil from the oil tank roller to the peripheral surface of the heating roller. This has the effect of uniformly applying oil to the peripheral surface of the heating roller.

According to a second aspect of the present invention, a cleaning member is provided between the outlet side of the belt nip portion and the oil transfer roller to contact the peripheral surface of the heating roller to remove the remaining deposits. There is an effect that after the fixing, the peripheral surface of the heating roller is cleaned, and then the oil is received from the oil tank roller onto the peripheral surface.

According to a third aspect of the present invention, the cleaning member is a cleaning roller which rotates in contact with the peripheral surface of the heating roller, and removes the adhered substance on the surface while rotating by contact with the heating roller. It has the effect of collecting.

According to a fourth aspect of the present invention, the outer surface of the nip portion between the oil transfer roller and the heating roller and the entrance side of the nip portion between the oil tank roller and the oil transfer roller contact the peripheral surface of the oil transfer roller. The cleaning member has a function of cleaning the oil transfer roller itself and performing both cleaning and oil application on the heating roller.

According to a fifth aspect of the present invention, the cleaning member is a cleaning roller that rotates in contact with the peripheral surface of the oil transfer roller. It has the effect of collecting kimono.

Hereinafter, embodiments of the present invention will be described. (Embodiment 1) FIG. 1 is a schematic view showing a main part of a fixing device according to a first embodiment of the present invention, which is applicable to, for example, various color laser beam printers.

In FIG. 1, a sheet 50 on which a toner image 51 transferred from a transfer device (not shown) has been transferred is placed in a nip portion between the heating roller 1 and a belt 2 which is in contact with the peripheral surface thereof. The toner image 51 is fixed on the surface of the sheet 50 by heating and pressurizing when the toner image is supplied and passes through the nip portion.

The heating roller 1 is a hollow cylindrical body which is connected to the output shaft of a motor (not shown) and is driven to rotate in the direction of arrow a in the figure. Of the heater 1a. The belt 2 is located between the entrance roller 3 and the peripheral surface of the heating roller 1.
, Which is wound around a pressure roller 4 for applying pressure while holding a coating layer, for example, a coating layer made of fluorine or the like having good releasability on the surface of a heat-resistant elastic body such as silicone rubber having a thickness of about 1 mm. Is formed.

The entrance roller 3 and the pressure roller 4 are both made of metal, and are idlers with their respective rotation axes parallel to the axis of the heating roller 1. The peripheral surface can be contacted within a range corresponding to the arc-shaped center angle. In the illustrated example, a heater 3a for heating the belt 2 is incorporated in the entrance roller 3.

In such a belt nip type fixing device, it is necessary to appropriately control the heating temperature at the time of fixing, and for this control, the surface temperature of the heating roller 1 and the nip of the belt are controlled. A temperature sensor for detecting a surface temperature is provided, and the heaters 1a and 3a are detected based on the detected temperature.
The calorific value of a is controlled by the controller.

In such a configuration, the toner image 5 is transferred after the transfer.
1 is supplied, the paper 50 passes through a belt nip portion between the heating roller 1 and the belt 2, and heat transfer from the heating roller 1 and the belt 2 during this passage. Thus, the toner image 51 can be fixed on the sheet 50.

Here, oil is applied to improve the releasability of the toner from the peripheral surface of the heating roller 1 to prevent offset of the melted toner to the heating roller 1 and to remove and remove the residual toner. A roller row for cleaning is provided at a position facing the belt 2 in the radial direction of the heating roller 1. These roller rows are an oil tank roller 5, an oil transfer roller 6, and a cleaning roller 7, all of which are idlers.

The oil tank roller 5 is hollow,
It comprises a metal tube 5a in which oil A is sealed, an infiltration paper 5b attached to the outer periphery thereof, and a felt 5c covering the outer peripheral surface thereof.
The oil A can be made to infiltrate the felt 5c from the infiltration paper 5b by making a minute hole in the peripheral wall of. The amount of infiltration of the oil A up to the felt 5c is much smaller than the amount of supply from the oil tank roller to the fixing device by the roller pair described in the conventional example.

The oil transfer roller 6 has a heat-resistant elastic body such as silicone rubber disposed on the surface of a metal roller, and is arranged with its peripheral surface in contact with both the heating roller 1 and the oil tank roller 5 as shown in the figure. When the heating roller 1 is rotationally driven by the drive motor, the oil transfer roller 6 rotates clockwise. The rotation of the oil transfer roller 6 causes the oil tank roller 5 to rotate.
Simultaneously rotates counterclockwise, and the rotation of these rollers 5, 6 applies oil A to the peripheral surface of the heating roller 1 via the oil transfer roller 6.

As described above, since the oil tank roller 5 is applied to the peripheral surface of the heating roller 1 with the oil transfer roller 6 interposed therebetween without directly contacting the heating roller 1, the oil A is After the surface is made uniform, it can be applied evenly along the peripheral surface of the heating roller 1.

The cleaning roller 7 is a metal roller or a heat-resistant elastic body disposed on the surface thereof, and has a peripheral surface thereof in contact with the heating roller 1. The heating roller 1 after fixing is completed. Of the oil transfer roller 6
It is located in the part that comes in contact earlier.

In the above configuration, the transferred paper 50 is supplied to the belt nip between the heating roller 1 and the belt 2, and the toner image is transferred to the paper 50 by the rotation of the heating roller 1 and the movement of the belt 2. After fixing the sheet 51, the sheet 50 is discharged from the apparatus. Then, throughout this fixing period, by contact with the peripheral surface of the heating roller 1,
The oil transfer roller 6 and the cleaning roller 7 rotate together, and at the same time, the oil tank roller 5 keeps rotating.

At the portion where the heating roller 1 comes off from the belt nip portion, first, the residual toner adhered to the surface thereof by contact with the cleaning roller 7 is removed. Therefore, when the heating roller 1 comes into contact with the oil transfer roller 6, it can be in a state where there is no toner or other foreign matter, and the occurrence of surface defects of the heating roller 1 and the oil transfer roller 6 is prevented.

The oil tank roller 5 rotates at the same time as the oil transfer roller 6 comes into contact with the oil transfer roller 6, and causes the oil A impregnated in the felt 5c on the outer peripheral surface to adhere to the peripheral surface of the oil transfer roller 6. Since the heating roller 1 and the belt 2 have a long belt nip portion, the supply amount of the oil A from the oil tank roller 5 can be reduced, and an oil tank roller in a fixing device having a conventional roller pair is used. As in the case, a large amount of oil is not required, and an operation without leakage of oil can be performed.
Therefore, the oil A does not leak or drip from the oil tank roller 5 at the time of operation or replacement, and maintenance of the apparatus and improvement of workability at the time of replacement are achieved.

(Embodiment 2) FIG. 2 is a schematic view showing a main part of a fixing device according to a second embodiment of the present invention.
The same members as those shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, the positional relationship among the oil tank roller 5, the oil transfer roller 6 and the cleaning roller 7 shown in FIG. It is arranged as a member capable of performing both functions of cleaning. Then, only the oil transfer roller 6 comes into contact with the peripheral surface of the heating roller 1, the oil tank roller 5 and the cleaning roller 7 come into contact with the oil transfer roller 6, and the rotation is transmitted. The application to the roller 6 and the cleaning roller 7 remove the deposits from the peripheral surface of the oil transfer roller 6 after applying the oil to the heating roller 1. A blade 8 is provided in the vicinity of the cleaning roller 7 for scraping off the adhering matter removed from the peripheral surface of the heating roller 1 in contact with the peripheral surface.
And the blade 8 collects and discards the attached matter.

As described above, the cleaning roller 7 is prevented from contacting the heating roller 1 and the oil transfer roller 6
By contacting only the rollers, the number of nip portions between the rollers with respect to the peripheral surface of the heating roller 1 can be reduced. After the surface of the oil transfer roller 6 is cleaned by the cleaning roller 7, the oil transfer roller 6 receives the oil A from the oil tank roller 5 and applies the oil A to the peripheral surface of the heating roller 1.

Therefore, since the peripheral surface of the oil transfer roller 6 itself has been cleaned, the peripheral surface of the heating roller 1 is cleaned simultaneously with the application of the oil A to the heating roller 1.

Accordingly, the oil transfer roller 6 can perform both functions of preventing the surface flaw of the heating roller 1 from occurring and cleaning. For this reason, if the positional relationship between the heating roller 1 and the oil transfer roller 6 is assembled with high accuracy, good transfer and cleaning can be performed, and the assembly can be simplified, so that a replaceable unit is formed. Is also possible.

(Embodiment 3) FIG. 3 is a schematic view showing a main part of a fixing device according to a third embodiment of the present invention.
Also in this example, the same members as those shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example, the rollers shown in FIG. 2 are constituted by uniting rollers 5, 6, and 7 for applying and cleaning oil to the heating roller 1, and these rollers 5 to 7 and The arrangement of the blade 8 is shown in FIG.
Exactly the same as

The fixing device has a well-known structure in which a housing 9 incorporated in a device such as a printer is used as an outer member. In this example, a roller array 5 is provided in a casing 10 detachable from the housing 9. 7 and the blade 8 are housed to form a unit.

That is, the casing 10 includes the rollers 5
7 are rotatably supported at both ends in the axial direction, and the blade 8 is fixed at a fixed position.
Bracket 1 for hooking on a pair of pins 9a provided on a side wall of a casing 9 whose both ends in the axial direction face each other.
0a. Then, attach the bracket 10a to the pin 9
When the oil transfer roller 6 is mounted on the housing 9 with the oil transfer roller a, only the oil transfer roller 6 comes into contact with the peripheral surface of the heating roller 1 as shown in the drawing.

As described above, since the casing 10 incorporating the rollers 5 to 7 and the blade 8 is detachably provided to the housing 9 of the fixing device 1, expensive members such as the heating roller 1 and the belt 2 are incorporated. The housing 9 can be easily replaced simply by removing the casing 10 containing the functional parts for cleaning and oil application. In the replacement work, since the oil tank roller 5 and the oil tank roller 5 are contained in the casing 10, even if an external force acts and oil leakage occurs, the oil leakage can be received only in the casing 10. 9 can be prevented from entering the oil.

[0043]

According to the present invention, since the oil tank roller is provided in the fixing device having a small toner offset by forming a long belt nip, the amount of oil supplied from the oil tank roller can be reduced to a small amount. As described above, the oil does not leak or drip at the time of replacement work or the like, so that the maintenance inside the device is achieved and the replacement work is simplified.

Since the oil from the oil tank roller is transferred to the heating roller via the oil transfer roller,
Oil can be applied evenly to the peripheral surface of the heating roller, and toner offset can be effectively suppressed.

In the case where only the oil transfer roller is brought into contact with the heating roller and the oil transfer roller is brought into contact with the oil tank roller and the cleaning roller, the oil transfer roller is required to simultaneously apply oil to the heating roller and perform cleaning. Therefore, the accuracy of assembling the members for applying and cleaning the oil to the heating roller can be reduced, and the assembly can be simplified.

Further, if the oil transfer roller, the oil tank roller, and the cleaning roller are unitized and incorporated in a casing, and this casing can be attached to and detached from the housing of the fixing device, expensive members such as a heating roller and a belt can be used. Only the members having low durability only for cleaning and oil application can be replaced, and the running cost can be reduced.

[Brief description of the drawings]

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

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

FIG. 3 is a schematic diagram showing a main part of a fixing device according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating roller 1a Heater 2 Belt 3 Entry roller 3a Heater 4 Pressure roller 5 Oil tank roller 5a Metal tube 5b Infiltration paper 5c Felt 6 Oil transfer roller 7 Cleaning roller 8 Blade 9 Housing 9a Pin 10 Casing 10a Bracket 50 Paper 51 Toner image

Claims (5)

[Claims] 1. A belt nip type fixing device comprising: a heating roller that is driven to rotate; and an endless belt that runs while forming a belt nip portion between the heating roller and a peripheral surface of the heating roller. An oil tank roller in which oil to be applied as a toner release layer is sealed on the peripheral surface of the oil tank roller and the peripheral surface of the oil tank roller is capable of infiltrating the oil, And an oil transfer roller for applying the oil to the peripheral surface of the heating roller. 2. The cleaning device according to claim 1, further comprising a cleaning member disposed between the outlet side of the belt nip portion and the oil transfer roller, the cleaning member being in contact with the peripheral surface of the heating roller to remove residual deposits. Belt nip type fixing device. 3. The belt nip type fixing device according to claim 2, wherein the cleaning member is a cleaning roller that rotates in contact with a peripheral surface of the heating roller. 4. An outer surface of the oil transfer roller between the oil transfer roller and the heating roller at a nip portion exit side and an oil tank roller at a nip portion entrance side to remove residual deposits. The belt nip type fixing device according to claim 1, further comprising a cleaning member. 5. A belt nip type fixing device according to claim 4, wherein said cleaning member is a cleaning roller which rotates in contact with a peripheral surface of said oil transfer roller.