JPH08202197A - Fixing device - Google Patents

Abstract

(57) [Summary] [Objective] By taking advantage of the provision of the first cleaning roller and the second cleaning roller, and further, cleaning the first cleaning roller in contact with the fixing roller pair to a state where there is always little dirt. Provided is a fixing device capable of preventing dirt from being reversely attached to a fixing roller. The fixing roller 3 is provided with a first cleaning roller 7 which is in contact with substantially the entire width of the fixing roller 3, and the first cleaning roller 7 is provided with a second cleaning roller 8 which is in contact with the entire width of the fixing roller 3. ing. The fixing roller 3, the first cleaning roller 7 and the second cleaning roller 8 are rotated in the same direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing roller pair which is fixed by passing a transfer material carrying an unfixed toner image thereon, and at least one fixing roller surface of the fixing roller pair. And a second cleaning roller arranged so as to contact the roller surface of the first cleaning roller.

[0002]

2. Description of the Related Art A fixing device of the above type is well known, and is attached to an image forming apparatus using powder toner such as a printer, a copying machine and a facsimile. This type of fixing device generally melts the toner by the heat of the fixing roller and fuses it to the transfer material. If the releasing property of the fixing roller is poor, some toner and paper dust adhere to the fixing roller, Then, an offset phenomenon occurs in which the transfer material is transferred to the transfer material again. In order to prevent such an offset phenomenon, various proposals have been made in the past, and Japanese Patent Application Laid-Open No. 57-105760 discloses a fixing device for preventing the offset phenomenon by bringing a cleaning roller into contact with the fixing roller. ing.

However, the fixing roller is in contact with it 1
If only one cleaning roller is provided, all the toner and the like wiped from the fixing roller remains attached to the surface of the cleaning roller. Moreover, the cleaning roller is always in contact with the fixing roller. For this reason, if the surface of the cleaning roller becomes excessively dirty due to use over time, there is a problem that the dirt is reversely attached to the fixing roller.

Therefore, Japanese Patent Laid-Open No. 61-86776 discloses a first cleaning roller which is in contact with the surface of a fixing roller.
A fixing device having a second cleaning roller that is in contact with the roller surface of the first cleaning roller is disclosed.
Cleaning roller> second cleaning roller. In the fixing device having the first and second cleaning rollers, the dirt on the first cleaning roller is wiped off by the second cleaning roller, so that when both the first and second cleaning rollers are completely dirty,
The fixing device itself has almost reached the end of its life, and there is little risk that dirt may be attached to the fixing roller by the dirt on the first and second cleaning rollers.

[0005]

However, in the fixing device described in Japanese Patent Laid-Open No. 61-86776, special devices for cooling and heating are required depending on the material of each roller in order to obtain an appropriate temperature difference. There was a problem that became. Furthermore, since the first and second cleaning rollers are sequentially driven by the rotation of the fixing roller, the cleaning properties of the first and second cleaning rollers are insufficient.
Therefore, there is a problem that some of the dirt transferred to the first cleaning roller returns to the fixing roller, or the dirt adheres to the roller and damages the fixing roller.

The present invention solves the above-mentioned conventional problems,
The advantage of providing the first cleaning roller and the second cleaning roller is utilized, and the first cleaning roller in contact with the pair of fixing rollers is always cleaned in a state where there is little dirt, so that the dirt is reversely attached to the fixing roller. It is an object of the present invention to provide a fixing device capable of preventing the above.

[0007]

To achieve this object, the present invention provides a fixing roller pair for fixing by passing a transfer material carrying an unfixed toner image, and at least one of the fixing roller pair. A fixing device having a first cleaning roller arranged in contact with the surface of the fixing roller and a second cleaning roller arranged in contact with the roller surface of the first cleaning roller,
The fixing roller, the first cleaning roller, and the second cleaning roller are all driven by drive means that rotate in the same direction.

Further, in order to achieve the above object, the present invention provides a roller pair of the fixing roller and the first cleaning roller and a roller pair of the first cleaning roller and the second cleaning roller which are in contact with each other. Are driven by driving means that rotate so as to come into contact with each other with a peripheral speed difference.

Furthermore, in order to achieve the above object, the present invention provides a roller pair of the fixing roller and the first cleaning roller and a roller of the first cleaning roller and the second cleaning roller which are in contact with each other. One of the roller pairs in the pair is rotated in the same direction, and the other roller pair is driven by a driving unit that rotates so as to come into contact with each other with a peripheral speed difference.

[0010]

According to the above structure, since the fixing roller, the first cleaning roller and the second cleaning roller are all driven by the driving means rotating in the same direction, good cleaning can be obtained between the rollers. The cleaning roller can clean dirt on the fixing roller and the second cleaning roller cleans dirt on the first cleaning roller, and can prevent dirt from adhering to the fixing roller.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side view showing a fixing device according to the present invention.

In FIG. 1, a fixing device 1 includes a fixing roller 3 having a heater 2 built therein and a pressure roller 4 which is pressed against the fixing roller 3 by a pressure spring 5 via a pressure arm 6.
The fixing roller 3 and the pressure roller 4 form a fixing roller pair. The fixing roller 3 and the pressure roller 4 are
Both are rotatably mounted via bearings (not shown), and the fixing roller 3 is further drivingly connected to driving means (not shown) such as a gear described later. The fixing roller 3 of this embodiment
Has a journal portion made of aluminum, and has a surface layer treated with, for example, a fluororesin as a release layer. This fluororesin processing is PFA, PTFE or the like. In the fixing device 1 of FIG. 1, reference numeral 10 is an inlet guide, 11 is a thermistor, 12 is a thermal fuse, 13 is a separating claw, and 14 is an outlet guide.

Even if the fixing roller 3 is coated with a fluororesin processing as a release layer, it is impossible to completely eliminate a slight amount of offset of toner and the like, and while tens of thousands of copies are made. It is unavoidable that the offset toner adheres to the fixing roller 3. For this reason,
The fixing device 1 of this embodiment is provided with a first cleaning roller 7 made of, for example, a metal roller, which contacts the fixing roller 3 over substantially the entire width thereof. The first cleaning roller 7 is rotationally driven in the same direction as the fixing roller 3, that is, in the clockwise direction in FIG.

Therefore, since the first cleaning roller 7 is rotated in the same direction as the fixing roller 3, the first cleaning roller 7 is rotated in the direction of scraping off the dirt and the like of the fixing roller 3 and the relative distance between the rollers. Since the speed becomes faster, its cleaning ability is higher than that of the one rotated together.
However, when the number of cleaning rollers is only one, as described above, the toner may adhere to the fixing roller 3 reversely with the lapse of time.

Therefore, the fixing device 1 of this embodiment is provided with the second cleaning roller 8 which is in contact with the first cleaning roller 7 over substantially the entire width thereof. This second
The cleaning roller 8 is also made of a metal roller, and is rotationally driven in the same direction as the first cleaning roller 7.

With this configuration, the cleaning ability of the second cleaning roller 8 is higher than that of the second cleaning roller 8 which rotates together with the first cleaning roller 7.
It is possible to scrape off the dirt on the cleaning roller 7 and always keep the first cleaning roller 7 clean. Therefore, it is possible to prevent the dirt from being reversely attached to the fixing roller 3 for a long period of time.

The drive means for rotationally driving the fixing roller 3, the first cleaning roller 7 and the second cleaning roller 8 in the same direction is fixed to a drive gear 20 driven by a drive source, as shown in FIG. A fixing gear 21 fixed to the shaft of the roller 3 meshes with the first cleaning roller gear 23 fixed to the shaft of the first cleaning roller 7 via an idler 22. The first cleaning roller gear 23 meshes with the second cleaning roller gear 25 fixed to the shaft of the second cleaning roller 8 via the idler 24. With this configuration, the fixing roller 3, the first cleaning roller 7 and All the second cleaning rollers 8 can be rotationally driven in the same direction. The driving means may use a belt instead of a gear to rotate the fixing roller 3, the first cleaning roller 7 and the second cleaning roller 8 in the same direction with one driving source. It is also possible to use separate drive sources for the fixing roller 3, the first cleaning roller 7, and the second cleaning roller 8.

FIG. 3 is an explanatory view showing another embodiment of the present invention. The rotation directions of the fixing roller 3, the first cleaning roller 7 and the first cleaning roller 7 and the second cleaning roller 8 will be described later. It is rotationally driven in opposite directions by the driving means. That is, the fixing roller 3, the first cleaning roller 7, and the second cleaning roller 8 are rotationally driven in the directions in which they rotate together. But,
The fixing roller 3 and the first cleaning roller 7, which are in contact with each other, and the first cleaning roller 7 and the second cleaning roller 8 are rotationally driven so as to be in contact with each other with a peripheral speed difference, and in this example, the first cleaning roller 7 Is set to be higher than that of the fixing roller 3, and the peripheral speed of the second cleaning roller 8 is set to that of the first cleaning roller 7.
Set faster than that. That is, when the peripheral speeds of the fixing roller 3, the first cleaning roller 7 and the second cleaning roller 8 are V ₁ , V ₂ and V ₃ , V ₁ <V ₂ <V ₃ is set.

In the fixing device 1 having such a configuration, even if the pair of fixing roller 3 and the first cleaning roller 7 rotate in opposite directions, the peripheral speed of the first cleaning roller 7 is the same as that of the fixing roller 3. Since the speed is higher than the peripheral speed, the cleaning ability of the first cleaning roller 7 is higher than that of the case where the first cleaning roller 7 rubs the surface of the fixing roller 3 violently and the first cleaning roller 7 rotates together. Further, even if the rotation direction of the roller pair of the first cleaning roller 7 and the second cleaning roller 8 is opposite, the peripheral speed of the second cleaning roller 8 is higher than that of the first cleaning roller 7. Since the speed is high, the second cleaning roller 8 rubs the surface of the first cleaning roller 7 violently, so that the cleaning ability of the second cleaning roller 8 is higher than that of the second cleaning roller 8 which rotates together. Therefore, the dirt attached to the first cleaning roller 7 from the fixing roller 3 is transferred to the second cleaning roller 8, and the first cleaning roller 7 can be always kept clean.

As the driving means for rotationally driving the fixing roller 3, the first cleaning roller 7 and the second cleaning roller 8 with a peripheral speed difference, as shown in FIG. 4, they are driven by a driving source. The fixing gear 21 fixed to the shaft of the fixing roller 3 meshes with the drive gear 20 that rotates, and the gear 21 meshes with the first cleaning roller gear 23 fixed to the shaft of the first cleaning roller 7,
A second cleaning roller gear 25 in which the cleaning roller gear 23 is fixed to the shaft of the second cleaning roller 8.
Bite into. And this drive means is for each gear 2
It is possible to set V ₁ <V ₂ <V ₃ by the gear ratio of _1, 23, 25.

FIG. 5 shows the fixing roller 3 of (1) and the first
And the first cleaning roller 7 and the fixing roller 3 of (2) have a peripheral speed difference, and the first cleaning roller 7 and the second cleaning roller 7 have a peripheral speed difference.
And the fixing roller 3, the first cleaning roller 7, the first cleaning roller 7 and the second cleaning roller 8 each having a peripheral speed difference. 9 is a graph showing the number of copies until dirt is reversely attached to the fixing roller 3 in the provided example.

As is apparent from this graph, it can be seen that the fixing device of the example (3) jumps out and has a long life.

Thus, in this embodiment, there is a difference in peripheral speed between the roller pair of the fixing roller 3 and the first cleaning roller 7 and the roller pair of the first cleaning roller 7 and the second cleaning roller 8 which are in contact with each other. The cleaning performance is improved by rotating the cleaning roller so that the cleaning performance is improved. In this case, the cleaning ability is increased in proportion to the difference in peripheral speed. It can be considered that this is due to the difference in the contact area per unit time and the difference in the mechanical scraping force. For example, when the peripheral speed ratio of the fixing roller 3 and the first cleaning roller 7 is 1: 2 and the releasability of both rollers is the same, the contact area per unit time is also 1: 2. Since the amount of adhered dirt per unit time is the same if the releasability is the same, the cleaning performance is higher when the peripheral speed ratio is larger.

The fixing roller 3 is A, the first cleaning roller 7 is B, and the second cleaning roller 8 is C.
And the next 4
For the two cases, the cleaning properties of the first cleaning roller 7 and the second cleaning roller 8 were compared. In this case, the conditions such as releasability of each roller are the same.

1. A: 10 cm / s, B: 10 cm / s, C;
It rotates with 10 cm / s. 2. A: 10 cm / s, B: 10 cm / s, C: 10 cm / s, rotating in the same direction. 3. A: 10 cm / s, B: 15 cm / s, C: 20 cm / s, and they are rotated in opposite directions. 4. A: 10 cm / s, B: 15 cm / s, C: 50 cm / s, which are rotated in opposite directions.

As a result, the case 2 was better than the case 1, and the cases 2 and 3 were almost the same, and the case 4 was better than the case 3.

By the way, in the present invention, the roller pair of the fixing roller 3 and the first cleaning roller 7 and the roller pair of the first cleaning roller 7 and the second cleaning roller 8 are in the rotational direction. Alternatively, the pair of rollers may be in the same direction and the other roller pair may have a peripheral speed difference. As the driving means in this case, the idlers 22 and 2 shown in FIG.
It suffices to eliminate any one of 4 and mesh the gear between them.

The first cleaning roller 7 and the second cleaning roller 8 of the present invention may be provided on the pressure roller 4 side.

[0030]

According to the first aspect of the present invention, good cleaning can be obtained between the rollers, the first cleaning roller stains the fixing roller, and the second cleaning roller stains the first cleaning roller. It is possible to securely perform the cleaning and prevent the dirt from being reversely attached to the fixing roller for a long period of time.

According to the second and third aspects of the invention, the dirt on the first cleaning roller can be reliably cleaned in the same manner as described above, and the dirt can be prevented from adhering to the fixing roller for a long period of time. Moreover, if the peripheral speed difference is set to be large, the cleaning property can be further improved.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a fixing device according to the present invention.

FIG. 2 is an explanatory view showing a driving means of the embodiment of FIG.

FIG. 3 is a side view of a main portion showing another embodiment of the fixing device according to the present invention.

FIG. 4 is an explanatory view showing a driving means of the embodiment of FIG.

FIG. 5 is a graph showing the number of copies until dirt is reversely attached to the fixing rollers of the three cases.

[Explanation of symbols]

 1 Fixing Device 3 Fixing Roller 4 Pressure Roller 7 First Cleaning Roller 8 Second Cleaning Roller

Claims (3)

[Claims] 1. A fixing roller pair which is fixed by passing a transfer material carrying an unfixed toner image thereon, and a first cleaning which is arranged so as to be in contact with at least one fixing roller surface of the fixing roller pair. In a fixing device having a roller and a second cleaning roller arranged in contact with the roller surface of the first cleaning roller, the fixing roller, the first cleaning roller, and the second cleaning roller are A fixing device characterized by being driven by driving means that rotate in the same direction. 2. A fixing roller pair which is fixed by passing a transfer material carrying an unfixed toner image, and a first cleaning which is arranged so as to be in contact with at least one fixing roller surface of the fixing roller pair. A fixing device having a roller and a second cleaning roller arranged so as to be in contact with the roller surface of the first cleaning roller, wherein a roller pair of the fixing roller and the first cleaning roller in contact with each other, and A fixing device characterized in that a roller pair of a first cleaning roller and a second cleaning roller is driven by a driving unit that rotates so as to come into contact with each other with a peripheral speed difference. 3. A fixing roller pair which is fixed by passing a transfer material carrying an unfixed toner image, and a first cleaning which is arranged so as to contact at least one fixing roller surface of the fixing roller pair. A fixing device having a roller and a second cleaning roller arranged so as to be in contact with the roller surface of the first cleaning roller, wherein a roller pair of the fixing roller and the first cleaning roller in contact with each other, and One roller pair in the roller pair of the first cleaning roller and the second cleaning roller is rotated in the same direction, and the other roller pair is driven by a driving unit that rotates so as to come into contact with each other with a peripheral speed difference. A fixing device characterized by the above.