JPH0429178A - Fusing device - Google Patents

Abstract

PURPOSE:To obtain an excellent image without stain at the time of fixing by varying the coating quantity of oil to a fixing roller by means of an oil coating means. CONSTITUTION:The oil coating means of the fixing roller is worked when running in trial is carried out without having the pass of a transfer sheet just after assembling is finished at a workshop, the coating of silicone oil to the fixing roller is carried out by the web of the oil coating means, and the feeding speed of the web is made higher than normal feeding speed at the time of copying. Therefore, when an user gets a copying machine, the surface of the fixing roller is already coated with the silicone oil of a necessary quantity, so that the silicone oil of the necessary quantity is secured on the surface of the fixing roller from the beginning, and the offset of toner to the fixing roller caused by the shortage of a silicone oil quantity on the surface of the fixing roller in an using initial stage, is prevented. Thus, the stain of the toner image on a transfer material is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. The present invention relates to an image forming apparatus such as a copying machine, a printer, a laser facsimile, etc., and particularly relates to an image forming apparatus such as a copying machine, a printer, a laser facsimile, etc. The present invention relates to an image forming apparatus that makes it possible to obtain good images free of time stains.

In an image forming apparatus such as a copying machine, a toner image formed by an image forming process such as electrostatic photography is transferred onto a transfer material, and the toner image is transferred onto the transfer material using a fixing device. It has become established.

FIG. 6 shows an example of a fixing device used in a conventional copying machine.

In Figure 6, the transfer paper on which the toner image has been transferred is A in the figure.
The toner image is inserted into the nip formed by the pair of fixing rollers 2 and the pressure roller 3 of the fixing device with the toner image on the fixing roller 2 side, and as it passes through the nip, the pressure and the built-in Heat is applied by the heater 4, and the toner image on the transfer paper is fixed and fixed to the transfer paper by melting the toner.

In such a fixing device, the fixing roller 2 is usually formed as a roller with a hard surface such as metal, and the pressure roller 3 is formed as a roller with a soft surface such as silicone rubber. used.

By the way, since the transfer paper is inserted into the nip between the fixing roller 2 and the pressure roller 3 with the toner image on the fixing roller 2 side, some toner from the toner image adheres to the fixing roller 2 in an offset manner. It is known that if this is left unattended, the offset toner mentioned above will adhere to the transfer paper in the subsequent fixing operation and will stain the toner image on the transfer paper.

Therefore, in order to prevent this, conventionally, the fixing device is provided with oil application means 20 on the fixing roller 2, which also serves as a cleaning means.

The oil application means 20 includes a web 5 made of sheet-like nonwoven paper, and the web 5 is impregnated with silicone oil as a release agent oil and wound around the unwinding shaft 8. The web 5 is driven to be wound up from an unwinding shaft 8 to a winding shaft 7 in conjunction with the passing movement of the transfer paper, and is pressed against the fixing roller 2 by a spring (not shown) by a web roller 6 made of an elastic material such as rubber. , this allows Web 5 to
The surface of the fixing roller 2 is wiped to remove dirt caused by offset on it, and impregnated silicone oil is evenly applied onto the surface of the fixing roller 2.

In addition, in FIG. 6, reference numeral 9 denotes a pressing member that abuts the web 5 to control the unwinding attitude of the web 5 from the unwinding shaft 8.

The silicone oil applied to the surface of the fixing roller 2 has the effect of increasing the releasability between the fixing roller 2 and the toner and reducing the offset of the toner to the fixing roller 2. The web 5 is wound by a predetermined amount by the take-up shaft 7, and the new surface of the web 5 always comes into contact with the fixing roller 2, and silicone oil is supplied to the fixing roller 2 and coated thereon.

If there is too much silicone oil applied to the fixing roller 2, the surface of the fixing roller 2 will not be able to hold the silicone oil, but the excess amount of silicone oil will transfer to the transfer paper and be carried away, and the surface of the fixing roller 2 will not be able to retain the silicone oil. The amount of silicone oil is always kept constant.

Since the silicone oil is supplied and applied using the above-described mechanism, the amount of silicone oil on the surface of the fixing roller 2 roughly changes as shown in FIG. 7.

However, the conventional oil application means 20 described above has the following drawbacks.

As shown in FIG. 7, in the conventional oil application means 20,
After the user starts using a new, unused copying machine until the number of copies is approximately 2,000, the amount of silicone oil on the surface of the fixing roller 2 due to application with the web 5 is completely reduced to the level indicated by the two-dot chain line in the figure. The amount of oil applied is less than 2.5g. In this state, the silicone oil is applied unevenly on the surface of the fixing roller 2, and the skin is exposed in some places on the surface, and even in the areas where silicone oil is applied, the amount of oil is It varies.

For this reason, the function of silicone oil as a release agent is insufficient, and there is a lot of toner offset to the fixing roller 2 at the initial stage of use (up to about 2000 copies).
There was a drawback that the transfer paper became heavily stained.

Therefore, an object of the present invention is to prevent toner offset to the fixing roller at the initial stage of use by securing a necessary amount of silicone oil on the surface of the fixing roller of the fixing device at the early stage of use. It is an object of the present invention to provide an image forming apparatus capable of obtaining a good image free from stains during fixing.

of ruta The above object is achieved by an image forming apparatus according to the present invention.

In summary, the present invention provides the following steps: While supplying and applying a release agent oil onto the surface of the fixing roller using an oil application means, a transfer material having a toner image transferred thereto is held between the fixing roller and the pressure roller. An image forming apparatus comprising a fixing device for fixing the toner image onto the transfer material, wherein the amount of oil applied to the fixing roller by the oil application means is made variable. .

According to one aspect of the present invention, the oil application means is made of a sheet-like nonwoven material impregnated with the oil, which applies the oil by being sent in contact with the surface of the fixing roller, and the nonwoven material is impregnated with the oil. By changing the feed speed of the fixing roller, the amount of oil applied to the fixing roller can be varied. According to another aspect, the amount of oil applied to the fixing roller is made variable by changing the amount of oil held in a portion of the sheet-like nonwoven material in the feeding direction.

Further, in the present invention, while supplying and applying a release agent oil onto the surface of the fixing roller by an oil application means, the transfer material having the toner image transferred thereto is held between the fixing roller and the pressure roller, thereby removing the toner. In an image forming apparatus equipped with a fixing device for fixing an image onto the transfer material, the oil is applied to the fixing roller in advance by an oil application means different from the oil application means when the fixing roller is new and unused. This is an image forming apparatus characterized by:

support Examples of the present invention will be described in detail below.

In order to prevent toner from being offset to the fixing roller of the fixing device in the initial stage of use of the image forming apparatus, the present invention includes the following steps:
Before using a new, unused image forming apparatus for the first time, apply the required amount of silicone oil to the fixing roller of the fuser unit (this may prevent the necessary amount of silicone oil from being applied to the fixing roller during the initial stage of use). It is to be ensured.

In this embodiment, the fixing roller 2 of the fixing device shown in FIG. The oil applying means 20 is operated to apply silicone oil to the fixing roller 2 using the web 5, and the feeding speed of the web 5 is set to be faster than the normal feeding speed during copying. is a major feature.

Figure 1(a) shows the time change in the cumulative feed amount of the web with respect to the operating time of the copying machine when the web is fed in the feeding mode of the present invention during a heat run of the copying machine. When sending the web in the sending mode of
FIG. 1(b) shows the change over time in the cumulative feed amount of the web with respect to the operating time of the copying machine. Both copy machine operating speeds are 10
The speed was set to be equivalent to a copying speed of 30 seconds per sheet. In addition, in FIG. 1(a), the time change of the cumulative web feed amount shown in FIG. 1(b) is added for reference.

This copying machine performs a heat run for 40 minutes, but since the copying machine operating speed is equivalent to a copying speed of 20 sheets/minute (10 sheets/30 seconds), the heat run time for 40 minutes is 20 minutes ( This corresponds to only 800 copies (sheets) x 40 = 800 copies. As mentioned in the conventional example, the fixing device fixes 0 for about 2000 sheets, and therefore, unless it fixes 0 for about 2000 sheets, the amount of silicone oil supplied to the fixing roller 2 will be insufficient and offset will increase. There is a drawback.

Therefore, during the heat run of the copying machine, the fixing roller 2 is coated with silicone oil while the web 5 of the oil coating means 20 is fed using the web feeding mode of the present invention.

According to the feeding mode of the present invention, as can be seen from FIG. 1(a), the web feeding speed is 0.5 mm·sec−1,
According to the normal feeding mode, as can be seen from Figure 1(b), the web feeding speed is 0°5/3 mm/sec.
It is 1. That is, the web feeding speed during heat run using the feeding mode of the present invention is three times the web feeding speed during copying using the normal feeding mode, and the amount of silicone oil supplied to the fixing roller is also approximately three times. It has become.

The web 5 is fed by driving a stepping motor (not shown) that is coaxial with the winding shaft 7 shown in FIG. The new surface of the fixing roller 2 is brought into contact with the surface of the fixing roller 2, and silicone oil is applied thereto. Therefore, in order to triple the web feeding speed, the rotational speed of the stepping motor described above should be tripled.

In this embodiment, as described above, during the heat run of the copying machine, the web is driven in the feeding mode shown in FIG. Since it is applied to the fixing roller, 800 (
The fixing roller 2 can be coated with silicone oil equivalent to 2400 copies (sheets) x 3 (sheets).

Therefore, when the copying machine is delivered to the user, the necessary amount of silicone oil has already been applied to the surface of the fixing roller 2, and the user has to apply the necessary amount of silicone oil on the surface of the fixing roller from the beginning of using the copying machine. can be ensured, and it is possible to prevent toner offset to the fixing roller 2 due to an insufficient amount of silicone oil on the surface of the fixing roller 2 at the initial stage of use.

Therefore, stains on the toner image on the transfer material due to the offset toner on the fixing roller 2 can be eliminated, and a good image can be obtained. Furthermore, the heat run time of the copying machine is not prolonged, and the cost of the copying machine is not increased.

Note that the opportunity to temporarily change the web feeding mode is not limited to the heat run, but may also be after the fixing device has been assembled as a unit, or when the copying machine is installed by a service person.

Other embodiments of the present invention will now be described. In this embodiment, during the heat run of the copying machine, the oil applying means 20 of the fixing roller 2 of the fixing device shown in FIG. The silicone oil is applied by increasing the silicone oil retention force at the forward end of the web 5 in the feeding direction.

FIG. 2(a) shows a side view of the web of the present invention, and FIG. 2(b) shows a side view of the web of the present invention.
The silicone oil content is shown in Figure 3 (a).
) is a side view of a conventional web, and (b) of the same figure shows its silicone oil content.

As shown in FIG. 2(a), the web 5 of the present invention is hung on the winding shaft 7, turned and folded back, so that the leading end portion 5a in the feeding direction is doubled over a length of 50 cm. It is thick. As a result, the front end portion 5a of the web 5 of the present invention has a high ability to retain silicone oil, as shown in FIG.
The silicone oil content of the corresponding portion of the conventional web 5 shown in a) is 15 g as shown in FIG. 3(b).
/ mm'', whereas the silicone oil content in the front end portion 5a is as much as 3.5 g/mm'' as shown in FIG. 2(b).

Therefore, by feeding the web 5 in the normal feeding mode and bringing it into contact with the fixing roller 2, even if silicone oil is applied to the fixing roller 2, the fixing roller 2 is can be applied with silicone oil when the feed mode is higher than normal.

By using the web 5 having a silicone oil content of 3.5 mm/g in the forward end portion 5a in the feeding direction as the oil application means 20 and feeding the web 5 in the normal feeding mode, the fixing roller 2 is coated with silicone oil. FIG. 4 shows the change in the amount of silicone oil on the surface of the fixing roller 2 with respect to the number of copies when the silicone oil is applied.

As is clear from this, the number of copies that exceeds 2.5 g of oil, which is the amount of oil that completely coats the roller surface indicated by the chain double-dashed line in the figure, is 2000 copies, which is the number of copies made using the conventional web 5 shown in FIG. It has been significantly shortened to 750 sheets.

As described in Embodiment 1, this copying machine performs a heat run for 40 minutes, which corresponds to 800 copies, so during the heat run, the web 5 with the above-mentioned leading end portion 5a in the feeding direction is doubled. If silicone oil is applied to the fixing roller 2, a necessary and sufficient amount of silicone oil has already been applied to the surface of the fixing roller 2 when the heat run is completed. In this embodiment, the silicone oil is applied to the fixing roller 2 during the heat run of the copying machine in the manner described above.

Therefore, according to this embodiment, as in the first embodiment, the necessary amount of silicone oil can be secured on the surface of the fixing roller from the beginning of the user's use of the copying machine.
It is possible to prevent toner offset to the fixing roller 2 due to an insufficient amount of silicone oil on the surface of the fixing roller 2 at the initial stage of use.

In the above, in order to increase the holding power of the silicone oil at the forward end portion 5a of the web 5 in the feeding direction, the portion 5a is
However, it goes without saying that the fibers of the web 5 may be made finer or thicker to increase the silicone oil retention ability of the front end portion 5a.

Further embodiments of the present invention will be described. This embodiment is characterized in that the fixing roller 2 of the fixing device shown in FIG. 6 is immersed in silicone oil before being assembled into the fixing device, and the surface of the fixing roller 2 is coated with silicone oil in advance.

As shown in FIG. 5, the fixing roller 2 is immersed in silicone oil 15 at a temperature of 100° C. stored in an oil tank 14 for 2 to 3 minutes, and then pulled out to remove excess silicone oil on its surface. A necessary amount of silicone oil 15 is applied onto the surface of the fixing roller 2 by wiping it with a sponge or the like.

At this time, silicone oil 15 on the surface of the fixing roller 2
If you wipe off too much silicone oil 15, there is no point in applying silicone oil 15 to the fixing roller 2.
Each time the silicone oil 15 is wiped off, the amount of silicone oil 15 applied to the surface of the fixing roller 2 is managed by wiping while measuring the weight increase of the fixing roller 2 from before being immersed in the silicone oil 15.

The fixing roller 2 has a weight of 780 g before being immersed in the silicone oil 15, and if the weight increases by 4.5 g or more due to immersion, the necessary amount of silicone oil 15 is added to the surface of the fixing roller 2.
is applied to the fixing roller 2 at the initial stage of use of the copying machine.
Since it is experimentally known that there is no offset of
Specifically, it may be controlled so that the weight after wiping minus the weight before dipping = 5±0.5 g.

Note that silicone oil 1 is used when dipping the fixing roller 2.
Needless to say, conditions such as the temperature and dipping time in step 5 depend on the material, surface condition, size, and amount of silicone oil required for the surface of the fixing roller 2.

According to this embodiment, when the copying machine is delivered to the user, the required amount of silicone oil 1 is already on the surface of the fixing roller 2.
5 is applied on the surface of the fixing roller 2 from the beginning of use of the copying machine by the user, and the amount of silicone oil on the surface of the fixing roller 2 is insufficient at the initial stage of use. This not only prevents the toner from being offset to the fixing roller 2 due to heat run, but also has the effect of being applicable to models with short heat run times because it can be carried out regardless of the heat run of the copier. .

In the above, silicone oil was applied in advance to the surface of the fuser roller 2 by immersing it in silicone oil before installing the fuser roller 2 in the fuser. Silicone oil may be applied manually onto the surface of the roller 2 in advance.

As explained above, in the image forming apparatus of the present invention, during the heat run, the fixing roller oil applying means of the fixing unit is operated at a faster web feeding speed than during fixing to impregnate the web. By applying techniques such as applying silicone oil to the fixing roller, we ensure that the required amount of silicone oil is already applied to the surface of the fixing roller when the image forming device is handed over to the user, even in the early stages of use. By ensuring a necessary amount of silicone oil on the surface of the fixing roller, toner offset to the fixing roller can be prevented, and a good image without stains during fixing can be obtained.

[Brief explanation of drawings]

FIG. 1(a) is a graph showing the change over time in the cumulative web feed amount with respect to the device operating time when the web is fed by the transfer roller oil applying means in the feed mode in an embodiment of the image forming apparatus of the present invention. be. FIG. 1(b) is a graph showing the change over time in the cumulative web feed amount with respect to the device operating time when the web is fed by the transfer roller oil application means in the same conventional feeding mode. FIG. 2(a) is a side view showing a web of a transfer roller oil application means in another embodiment of the image forming apparatus of the present invention. FIG. 2(b) is a side view of the web of FIG. FIG. 3(a) is a side view showing a web of a transfer roller oil application means of a conventional image forming apparatus. FIG. FIG. 4 is a graph showing the silicone oil content of the web shown in FIG. 2(a). FIG. FIG. 5 is an explanatory diagram showing a method of applying silicone oil before incorporating a transfer roller in an image device according to still another embodiment of the present invention. FIG. 7 is a configuration diagram showing a fixing device in the image forming apparatus. FIG. 7 shows the number of copies and the number of copies made while applying silicone oil to the surface of the fixing roller using the web of the transfer roller oil applying means of the fixing device shown in FIG. 6. It is a graph showing the relationship with the oil amount. a: Fixing roller: Pressure roller: Web: Tip portion (2) Oil layer: 20 silicone oil (20) Oil application means (1) Wear' Feeding amount [mm] n

Claims (1)

[Scope of Claims] 1) By supplying and applying a release agent oil onto the surface of the fixing roller by an oil application means, and sandwiching the transfer material to which the toner image has been transferred between the fixing roller and the pressure roller. An image forming apparatus comprising a fixing device for fixing the toner image onto the transfer material, wherein an amount of the oil applied to the fixing roller by the oil application means is made variable. 2) The oil application means is made of a sheet-like nonwoven material impregnated with the oil, which applies the oil by being fed into contact with the surface of the fixing roller, and the feeding speed of the nonwoven material is changed. The image forming apparatus according to claim 1, wherein the amount of the oil applied to the fixing roller is variable. 3) The oil applying means is made of a sheet-like non-woven material impregnated with the oil, which applies the oil by being sent in contact with the surface of the fixing roller, and is arranged in a direction in which the sheet-like non-woven material is fed. 2. The image forming apparatus according to claim 1, wherein the amount of the oil applied to the fixing roller is variable by changing the amount of the oil held in each portion. 4) While supplying and applying a release agent oil onto the surface of the fixing roller using an oil application means, the transfer material to which the toner image has been transferred is held between the fixing roller and the pressure roller, thereby transferring the toner image to the surface of the fixing roller. In an image forming apparatus equipped with a fixing device that fixes onto a transfer material, the oil is applied to the fixing roller in advance when it is new and unused by an oil application means different from the oil application means. An image forming apparatus characterized by: